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Tumour necrosis factor-alpha, interleukin-1beta and interleukin-8 induce persistent mechanical nociceptor hypersensitivity
Abstract
It has been previously described that daily intraplantar (i.pl.) injections of prostaglandin E2 (PGE2) and dopamine in rats for 14 days cause the development of a persistent mechanical nociceptor hypersensitivity state lasting more than 30 days. Considering that during inflammation, the release of these hyperalgesic agents are mediated by cytokines, we investigated in the present study whether interleukin-1beta (IL-1beta), IL-8 and tumour necrosis factor-alpha (TNF-alpha) are able to induce persistent mechanical nociceptor hypersensitivity. Daily i.pl. administration of TNF-alpha, IL-1beta or IL-8 for 18 days led to persistent mechanical nociceptor hypersensitivity, which lasted at least 30 days after the cessation of treatment. The co-treatment of the animals with IL-1beta plus indomethacin, but not with atenolol, prevented the induction of persistent mechanical nociceptor hypersensitivity. The co-treatment of the animals with IL-8 plus atenolol, but not with indomethacin, prevented the induction of persistent mechanical nociceptor hypersensitivity. The daily co-treatment of TNF-alpha with either indomethacin or atenolol partially inhibited (+/-50%) the induction of persistent mechanical nociceptor hypersensitivity. However, the combined treatment with indomethacin plus atenolol abolished the induction of the persistent mechanical nociceptive hypersensitivity by TNF-alpha.A single injection of cytokines in the contralateral paws of the animals with persistent hypersensitivity caused only an acute nociceptive response. This observation, together with the demonstration of undetectable levels of immunoglobulins against TNF-alpha, IL-1beta or IL-8 in the sera of animals after the development of the persistent hypersensitivity induced by those cytokines, indicate that this event is not due to an ongoing immunological response against the cytokines. In conclusion, our results support the suggestion that IL-1beta- and IL-8-induced persistent mechanical nociceptor hypersensitivity results from the endogenous release of eicosanoids and sympathetic amines, respectively. However, TNF-alpha-induced mechanical nociceptor hypersensitivity results from the concomitant endogenous release of eicosanoids and sympathomimetic mediators.
... Sensitization of the sensory nerve fibers, among which the nociceptive fibers, is the predominant phenomenon and is the common denominator for the inflammatory pain that induces the appearance of hyperalgesia, through peripheral or medullary mechanisms (6) . Prostaglandins and sympathomimetic amines participate in the inflammatory process, and anti-inflammatory drugs and analgesics interfere in this inflammatory process (6) . ...
... Sensitization of the sensory nerve fibers, among which the nociceptive fibers, is the predominant phenomenon and is the common denominator for the inflammatory pain that induces the appearance of hyperalgesia, through peripheral or medullary mechanisms (6) . Prostaglandins and sympathomimetic amines participate in the inflammatory process, and anti-inflammatory drugs and analgesics interfere in this inflammatory process (6) . The aim of the present study was to evaluate the effect of different drugs (dexamethasone, indomethacin, atenolol and morphine) on hyperalgesia induced by the nucleus pulposus on the nerve root ganglion in the absence of mechanical compression. ...
... Sensitization of the receptors is the common denominator in the inflammatory process involved in the mechanism for inflammatory pain. Functional regulation of the pain receptors leads to a state of hyperalgesia or allodynia, and there are two groups of mediators involved in this process, acting directly to sensitize the nociceptors: eicosanoids and sympathomimetic amines (6) . The capacity of these mediators to sensitize pain receptors has been demonstrated in animals and humans (6) . ...
Objective:
To evaluate the effect of anti-inflammatory drugs (dexamethasone, indomethacin, atenolol and indomethacin plus atenolol) and analgesic drugs (morphine) on hyperalgesia experimentally induced by the nucleus pulposus (NP) in contact with the L5 dorsal root ganglion (DRG).
Methods:
Thirty male Wistar rats of weights ranging from 220 to 250 g were used in the study. Hyperalgesia was induced by means of a fragment of NP removed from the sacrococcygeal region that was placed in contact with the L5 dorsal root ganglion. The 30 animals were divided into experimental groups according to the drug used. The drugs were administered for two weeks after the surgical procedure to induce hyperalgesia. Mechanical and thermal hyperalgesia was evaluated using the paw pressure test, von Frey electronic test and Hargreaves test, over a seven-week period.
Results:
The greatest reduction of hyperalgesia was observed in the group of animals treated with morphine, followed by dexamethasone, indomethacin and atenolol. Reductions in hyperalgesia were observed after drug administration ceased, except for the group of animals treated with morphine, in which there was an increase in hyperalgesia after discontinuation of the treatment.
Conclusion:
Hyperalgesia induced by NP contact with the DRG can be reduced through administration of anti-inflammatory and analgesic drugs, but a greater reduction was observed with the administration of dexamethasone.
... IL1B is considered as one of the proinflammatory cytokines, which is highly associated with inflammatory pain [52,53]. IL1B promotes the endogenous release of eicosanoid, which can cause persistent mechanical nociceptor hypersensitivity [52]. ...
... IL1B is considered as one of the proinflammatory cytokines, which is highly associated with inflammatory pain [52,53]. IL1B promotes the endogenous release of eicosanoid, which can cause persistent mechanical nociceptor hypersensitivity [52]. Intraarticular injection of IL1RN/IL-1Ra (interleukin 1 receptor antagonist) could alleviate pain of acute anterior cruciate ligament knee injury [54]. ...
Synovitis is implicated in the pathology of osteoarthritis (OA) and significantly contributes to the development of OA. As a noninvasive physical therapy, low-intensity pulsed ultrasound (LIPUS) has been reported to possess anti-inflammatory effect in recent years. However, the role of LIPUS on synovitis of OA and the underlying mechanisms are little known. The present study showed that LIPUS ameliorated synovial inflammation in destabilization of the medial meniscus (DMM) mouse model and air pouch model, and alleviated pain gait patterns of DMM mouse. LIPUS dramatically inhibited the production of mature IL1B/IL-1β (interleukin 1 beta) in vitro and in vivo. In addition, LIPUS upregulated the macroautophagy/autophagy level as well as accelerated the formation of an SQSTM1 (sequestosome1)-PKM (pyruvate kinase, muscle) complex in the lipopolysaccharide (LPS)-adenosine triphosphate (ATP)-treated macrophages. Besides, LIPUS downregulated the level of PKM2 in LPS-ATP-treated macrophages, which could be reversed by SQSTM1 knockdown. In brief, the present study for the first time demonstrates that LIPUS inhibits the production of mature IL1B partially via SQSTM1-dependent autophagic degradation of PKM2 in LPS-ATP-treated macrophages, which may further ameliorate the synovial inflammation and gait patterns in animal models. Our data provide new clues for the treatments of synovitis and other inflammatory diseases using LIPUS.
Abbreviations:
3-MA: 3-methyladenene; ATG7: autophagy-related 7; ATP: adenosine triphosphate; BafA1: bafilomycin A1; BMDMs: bone marrow derived macrophages; CHX: cycloheximide; DMM: destabilization of the medial meniscus; ELISA: enzyme-linked immunosorbent assay; GFP: green fluorescent protein; IL1B/IL-1β: interleukin 1 beta; LIPUS: low-intensity pulsed ultrasound; LIR: LC3-interacting region; LPS: lipopolysaccharide; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MDP: muramyl dipeptide; NFKB/NF-κB: nuclear factor kappa B; NLRP3: NLR family, pyrin domain containing 3; OA: osteoarthritis; PKM/PKM2: pyruvate kinase M1/2; PMA: phorbol-12-myristate-13-acetate; PYCARD/ASC; PYD and CARD domain containing; RFP: red fluorescent protein; siRNAs: small interfering RNAs; SQSTM1: sequestosome 1; TEM: transmission electron microscopy.
... Inflamed synoviocytes secrete pro-inflammatory and catabolic factors, such as interleukin (IL)-1β, IL-6, tumor necrosis factor α, and matrix metalloproteinases (MMPs), which promote cartilage inflammation, apoptosis and degradation [2,5,6]. Among those mediators, IL-1β is considered a key target because it induces the production of MMPs and the degradation of type II collagen, and is involved in the transmission of pain [7][8][9][10]. Therefore, it has been proposed that inhibition of the IL-1β pathway in the synovium could prevent the degradation of joint cartilage during the pathogenesis of OA. ...
... The quantity of pDNA-CrmA release from the HA/CS-CrmA nanoparticles was measured by dissolving HA/CS-CrmA nanoparticles in phosphate-buffered saline (pH 7.4) at 37 °C in a shaker bath at 135 rpm. At appropriate time intervals (1,4,7,10,13,16,19, and 22 days), samples were centrifuged to collect the supernatants for analysis. The amount of pDNA-CrmA released into the supernatant was determined by spectrophotometer (DU640; Beckman, Fullerton, CA, USA) at 260 nm. ...
Background/aims:
Interleukin (IL)-1β plays an essential role in the pathophysiology of osteoarthritis (OA). Cytokine response modifier A (CrmA) can prevent the generation of active IL-1β. This study aimed to explore the chondroprotective effects of hyaluronic acid-chitosan nanoparticles containing plasmid DNA encoding CrmA (HA/CS-CrmA) in a rat OA model.
Methods:
HA/CS-CrmA nanoparticles were synthesized through the complex coacervation of cationic polymers. The characteristics, toxicity, and transfection of the nanoparticles were investigated. Furthermore, the potential effects of HA/CS-CrmA nanoparticles were evaluated via a rat anterior cruciate ligament transection (ACLT) model of OA. Cartilage damage and synovial inflammation were assessed by safranin O/fast green and hematoxylin and eosin staining. Type II collagen in cartilage was measured by immunohistochemistry, and the expression levels of IL-1β, matrix metalloproteinase (MMP)-3, and MMP-13 in synovial tissue were detected by western blot.
Results:
The HA/CS-CrmA nanoparticles, which effectively entrapped plasmid DNA, showed an adequate size (100-300 nm) and a regular spherical shape. The nanoparticles safely transfected synoviocytes and released plasmid DNA in a sustained manner over 3 weeks. Additionally, HA/CS-CrmA nanoparticles significantly inhibited cartilage damage, synovial inflammation, and the loss of type II collagen induced by ACLT. The expression levels of IL-1β, MMP-3, and MMP-13 in synovial tissue were dramatically down-regulated by HA/CS-CrmA nanoparticles.
Conclusions:
These results suggested that HA/CS-CrmA nanoparticles could attenuate cartilage destruction and protect against early OA by inhibiting synovial inflammation via inhibition of IL-1β generation.
... Interleukin-1β (IL-1β), a member of IL-1 family, as the first discovered cytokine [15] is associated with peripheral sensitization [16] and the development and maintenance of inflammatory pain [17,18]. IL-1β injection produces mechanical hypernociception in rats [19]. IL-1 receptor antagonist (IL-1ra) administration significantly reduces IL-1β-induced enhancement of nociceptive neuron responses [20] and inflammatory hyperalgesia [21]. ...
... IL-1β was an important regulator of Nav1.7. Although IL-1β alters primary neural activity or sensitivity and contributes to inflammatory pain [16,19,60], the exact (See figure on previous page.) Fig. 5 Intratrigeminal ganglionic injection of IL-1β resulted in decrease in the head withdrawal threshold and upregulation of Nav1.7, ...
Background:
The proinflammatory cytokine interleukin-1β (IL-1β) drives pain by inducing the expression of inflammatory mediators; however, its ability to regulate sodium channel 1.7 (Nav1.7), a key driver of temporomandibular joint (TMJ) hypernociception, remains unknown. IL-1β induces cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2). We previously showed that PGE2 upregulated trigeminal ganglionic Nav1.7 expression. Satellite glial cells (SGCs) involve in inflammatory pain through glial cytokines. Therefore, we explored here in the trigeminal ganglion (TG) whether IL-1β upregulated Nav1.7 expression and whether the IL-1β located in the SGCs upregulated Nav1.7 expression in the neurons contributing to TMJ inflammatory hypernociception.
Methods:
We treated rat TG explants with IL-1β with or without inhibitors, including NS398 for COX-2, PF-04418948 for EP2, and H89 and PKI-(6-22)-amide for protein kinase A (PKA), or with adenylate cyclase agonist forskolin, and used real-time PCR, Western blot, and immunohistofluorescence to determine the expressions or locations of Nav1.7, COX-2, cAMP response element-binding protein (CREB) phosphorylation, and IL-1β. We used chromatin immunoprecipitation to examine CREB binding to the Nav1.7 promoter. Finally, we microinjected IL-1β into the TGs or injected complete Freund's adjuvant into TMJs with or without previous microinjection of fluorocitrate, an inhibitor of SGCs activation, into the TGs, and evaluated nociception and gene expressions. Differences between groups were examined by one-way analysis of variance (ANOVA) or independent samples t test.
Results:
IL-1β upregulated Nav1.7 mRNA and protein expressions in the TG explants, whereas NS398, PF-04418948, H89, or PKI-(6-22)-amide could all block this upregulation, and forskolin could also upregulate Nav1.7 mRNA and protein expressions. IL-1β enhanced CREB binding to the Nav1.7 promoter. Microinjection of IL-1β into the TGs or TMJ inflammation both induced hypernociception of TMJ region and correspondingly upregulated COX-2, phospho-CREB, and Nav1.7 expressions in the TGs. Moreover, microinjection of fluorocitrate into the TGs completely blocked TMJ inflammation-induced activation of SGCs and the upregulation of IL-1β and COX-2 in the SGCs, and phospho-CREB and Nav1.7 in the neurons and alleviated inflammation-induced TMJ hypernociception.
Conclusions:
Glial IL-1β upregulated neuronal Nav1.7 expression via the crosstalk between signaling pathways of the glial IL-1β/COX-2/PGE2 and the neuronal EP2/PKA/CREB/Nav1.7 in TG contributing to TMJ inflammatory hypernociception.
... Inflammatory mediators are concerned with the nociceptive peripheral type 13 , whereas lesion or dysfunction of the peripheral and central nervous system 14 or, according to the new classification, lesion or disease affecting the somatosensory system 15 is related to the neuropathic category. In both types, cytokines such as TNF-α, IL-1, IL-6 and IL-8 are involved [16][17][18][19] at least in the initial or late stages of the conditions. Patients with TSP/HAM seem to present both types of pain, although this distinction has not been accurately made by the authors. ...
... It is known that in TSP/HAM the key pathological event is an inflammatory demyelinating lesion in the spinal cord consequent upon immune mechanisms involv-ing cytokines, such as IFN-γ and TNF-α 39,40 , and this may be expressed mainly in the beginning of the neurological symptoms, but also along the disease, declining, however, with the disease duration 41 . It is also clear that in inflammatory nociceptive and neuropathic pain, cytokines such as TNF-α, IL-1, IL-6 and IL-8 [16][17][18][19] are mainly implicated. It is reasonable therefore to propose that pain may be a clinical marker of impending or continuing lesion. ...
OBJECTIVE: Tropical Spastic Paraparesis/HTLV-I Associated Myelopathy (TSP/HAM) is a chronic myelopathy, and pain has been mentioned as a frequent sensory symptom in this condition. The authors aimed at analyzing this symptom in a TSP/HAM patients series. METHOD: For this, 46 patients were analyzed considering demographic and clinical characteristics and complaint of pain as to verbal description, time of onset and classification, correlated with the degree of motor disability and type of pain. RESULTS: Among the 46 TSP/HAM patients, 28 (60.8%) complained of pain, predominant in the early phase of the disease. Most of the patients exhibited neuropathic characteristics of pain, correlated with increased motor disability. CONCLUSION: Pain in TSP/HAM patients is a frequent and early symptom, and the neuropathic type is predominant (57.1%) and paralleled with increased incapacitation. The pathogenic involvement of cytokines may possibly be involved in the meaning of this symptom in this condition.
... IL-8 acts through the receptor CXCR1/CXCR2 during inflammation. Previous studies demonstrated that IL-8 is involved in long lasting mechanical hypersensitivity that persists even after an inflammatory response has resolved [20], again consistent with our in vivo and in vitro findings on painful NOS CM. Lastly, another study demonstrated that intraplantar injection of CXCL5 into the rat paw caused a dose-dependent reduction in mechanical pain thresholds compared to vehicle control, which returned to baseline levels by 24 hours [21]. ...
The majority of schwannomatosis (SWN) patients experience debilitating pain. Yet, it is not known why only some schwannomas cause pain or whether mutations in SWN-related genes, (SMARCB1 or LZTR1) differentially influence pain signaling pathways. Here, we established cell lines from SWN tumors resected from patients with varying degrees of pain and bearing mutations in different SWN-related mutations. Compared with conditioned medium (CM) collected from nonpainful SWN tumors, CM from painful SWN tumors contained elevated levels of specific inflammatory cytokines (IL-6, IL-8, VEGF), and was able to enhance sensory neuron responsiveness to noxious TRPV1 and TRPA1 agonists in vitro. In in vivo studies, injection of CM from painful SWN into the hind paws of healthy mice evoked both more acute pain behavior and greater enhancement of mechanical stimulus-evoked behavioral responses than did CM from nonpainful SWN. Furthermore, the behavioral effects of painful CM differed as a function of the SWN-related gene mutations identified in the tumors of origin. Painful SMARCB1 mutant CM, for example, sensitized mice to mechanical stimulation at low forces, compared to non-painful tumor CM and control media, but this effect waned over time. In contrast, CM from a painful tumor with no detectable mutation in either SMARCB1 or LZTR1 caused the greatest increase in responsiveness to low mechanical forces and this effect lasted for 2 days post-injection. These experiments establish a paradigm for examining the mechanisms by which painful SWN tumors bearing different mutations produce their sensory effects and will thus facilitate better understanding and, potentially, treatment of the pain endured by SWN patients.
... Furthermore, we isolated primary rat chondrocytes and evaluated the expression level of YAP in vitro. Notably, Pro-inflammatory factors are known to play a crucial role in the occurrence and progression of OA [34]. To verify the expression of YAP in inflammatory chondrocytes, we applied IL-1β to establish the inflammatory-degenerative cell model. ...
Background
Osteoarthritis (OA) is a degenerative disease characterized by chronic inflammation of the joint. As the disease progresses, patients will gradually develop symptoms such as pain, physical limitations and even disability. The risk factors for OA include genetics, gender, trauma, obesity, and age. Unfortunately, due to limited understanding of its pathological mechanism, there are currently no effective drugs or treatments to suspend the progression of osteoarthritis. In recent years, some studies found that low-intensity pulsed ultrasound (LIPUS) may have a positive effect on osteoarthritis. Nonetheless, the exact mechanism by which LIPUS affects osteoarthritis remains unknown. It is valuable to explore the specific mechanism of LIPUS in the treatment of OA.
Methods
In this study, we validated the potential therapeutic effect of LIPUS on osteoarthritis by regulating the YAP–RIPK1–NF-κB axis at both cellular and animal levels. To verify the effect of YAP on OA, the expression of YAP was knocked down or overexpressed by siRNA and plasmid in chondrocytes and adeno-associated virus was injected into the knee joint of rats. The effect of LIPUS was investigated in inflammation chondrocytes induced by IL-1β and in the post-traumatic OA model.
Results
In this study, we observed that YAP plays an important role in the development of osteoarthritis and knocking down of YAP significantly inhibited the inflammation and alleviated cartilage degeneration. We also demonstrated that the expression of YAP was increased in osteoarthritis chondrocytes and YAP could interact with RIPK1, thereby regulating the NF-κB signal pathway and influencing inflammation. Moreover, we also discovered that LIPUS decreased the expression of YAP by restoring the impaired autophagy capacity and inhibiting the binding between YAP and RIPK1, thereby delaying the progression of osteoarthritis. Animal experiment showed that LIPUS could inhibit cartilage degeneration and alleviate the progression of OA.
Conclusions
These results showed that LIPUS is effective in inhibiting inflammation and cartilage degeneration and alleviate the progression of OA. As a result, our results provide new insight of mechanism by which LIPUS delays the development of osteoarthritis, offering a novel therapeutic regimen for osteoarthritis.
... The neuroinflammation lead to a double response: (i) a peripheral sensitization, mediated by an excessive response of primary afferent nociceptive neurons to external exogenous stressful [21], expressed phenotypically by throbbing pain, exacerbated by bending over or coughing [17]. The nociceptors and inflammatory mediators involved are bradykinin, histamine, serotonin, prostaglandin E2 and interleukins 1, 6 and 8 and tumour necrosis factor-alpha [16,22], and (ii) a central sensitization which is caused by hyperexcitability of nociceptive neurons in the dorsal horn of the spinal cord [16]. This process is mediated by the CGRP, which has a pivotal role in [11] the nociceptive transmission and migraine chronification. ...
Chronic migraine belongs to the "chronic long-duration headaches", and it is associated to high burden and significant economic impact. Treatment for both episodic (EM) and chronic migraine (CM) is based on the management of acute attacks and their prevention. For moderate/severe attacks, pharmacological therapies are triptans, dihydroergotamine nasal sprays or injections or neuroleptics, non-steroidal anti-inflammatory drugs, and corticosteroids. Chronic migraine belongs to the "chronic long-duration headaches", and it is associated to high burden and significant economic impact. Treatment for both episodic (EM) and chronic migraine (CM) is based on the management of acute attacks and their prevention. For moderate/severe attacks, pharmacological therapies are triptans, dihydroergotamine nasal sprays or injections or neuroleptics, non-steroidal anti-inflammatory drugs, and corticosteroids. The pathophysiology of CM is characterized by an abnormal activation of the trigemino-vascular system in the meninges causing a neurogenic inflammation, which explains the use of anti-inflammatory during attacks. It seems that the objective of the preventive therapy with the botulin toxin OnaBoNT-A consists in interrupting the release of CGRP and other neuropeptides as well as the activation of C-fiber nociceptor and of the nearby A-delta fibers. The protocol for migraine treatment with OnaBoNT-A injections consists of 31-39 pericranial injection sites involving seven muscle groups bilaterally in specific areas of the head and neck, with a total dose of between 155 and 195 units, every three months. The severe adverse events reported with high doses of botulin toxin for spasticity, have not been reported for CM treated with OnabotA at the labeled dose. The established improvement with onabotulinumtoxinA treatment in CM patients had a positive impact not only in reduction monthly headache days but also in improving quality of life, with reduction in both healthcare resource utilisation (HRU) and work impairment. Aim of this review was to give an overview on the use of BoNT-A in patients with CM, giving practical advices on the clinical indications.
... Our results also revealed significant differences in IL-8/CXCL8 tear levels among the study groups, with the P/DE-nonRS patients having the highest concentration followed by the DE-nonRS patients. IL-8/CXCL8 is a pain-associated molecule that induces persistent mechanical nociceptor hypersensitivity together with TNF-α and IL-1β (Enríquez- de--Salamanca et al., 2010;Sachs et al., 2002). Some authors suggest that IL-8/CXCL8 plays an important role in neuropathic pain following nerve injury or disc herniation Kim et al., 2011). ...
The purpose of this study was to analyze inflammation- and pain-related molecules in tears of patients suffering from chronic ocular pain associated with dry eye (DE) and/or a previous corneal refractive surgery (RS). Based on history, symptomatology, and clinical signs, the subjects (n = 180, 51.0 ± 14.7 years, 118 females, 62 males) in this cross-sectional study were assigned to one of five groups: DE and chronic ocular pain after RS (P/DE-RS, n = 52); asymptomatic subjects, i.e., without DE and chronic ocular pain, after RS (A-RS, n = 30); DE and chronic ocular pain without previous RS (P/DE-nonRS, n = 31); DE, no pain, and no previous RS (DE-nonRS, n = 35); and asymptomatic subjects with no previous RS (controls, n = 32). The tear concentrations of 20 cytokines and substance P (SP) were analyzed by immunobead-based assay and enzyme-linked immunosorbent assay, respectively. We found that tear levels of interleukin (IL)-10 and SP were increased in the RS groups. There were significant differences in IL-8/CXCL8 among the five groups. Nerve growth factor (NGF) tear levels were significantly higher in P/DE-RS than in DE-nonRS and controls. IL-9 had the highest percentage of detection in the P/DE-RS and P/DE-nonRS groups, while macrophage inflammatory protein (MIP)-1α, IL-2, and interferon (IFN)-γ were higher in the P/DE-RS, A-RS, and P/DE-nonRS groups. IL-17A was detected only in the A-RS group. Moderate correlations were observed in the A-RS, P/DE-nonRS, DE-nonRS and controls groups. A positive correlation was obtained between growth related oncogene concentration and tear break-up time (rho = 0.550; p = 0.012), while negative correlation was found between monocyte chemoattractant protein-3/CCL7 and conjunctival staining (rho = −0.560; p = 0.001), both in the A-RS group. IL-10 correlated positively with ocular pain intensity (rho = 0.513; p = 0.003) in the P/DE-nonRS group. Regulated on Activation Normal T Cell Expressed and Secreted/CCL5 correlated negatively with conjunctival staining (rho = −0.545; p = 0.001) in the DE-nonRS group. SP correlated negatively with corneal staining (rho = −0.559; p = 0.001) in the controls. In conclusion, chronic ocular pain was associated with higher IL-9 tear levels. IL-10, SP, MIP-1α/CCL3, IL-2, and IFN-γ were associated with previous RS. Higher levels of IL-8/CXCL8, MIP-1α/CCL3, IL-2, and IFN-γ were associated with DE-related inflammation, while NGF levels were related to chronic ocular pain and DE in RS patients. These findings suggest that improved knowledge of tear cytokines and neuromodulators will lead to a more nuanced understanding of how these molecules can serve as biomarkers of chronic ocular pain, leading to better therapeutic and disease management decisions.
... Specifically, TNF-α, IL-1, and NGF can modulate pain via nociceptor sensitization. 16,17 In particular, the expression of NGF can be induced by the upregulation of IL-1 and TNF-α in the case of OA. 18,19 The understanding of the cytokine network associated with the pathogenesis of OA has enhanced the rationale of studies exploring whether this biotherapeutic approach has an effect on symptom improvement. ...
Background
We aimed to evaluate the efficacy and safety of biologic agents targeting three main cytokines, that is, nerve growth factor (NGF), interleukin-1 (IL-1), and tumor necrosis factor-α (TNF-α), for osteoarthritis (OA) treatment.
Methods
Databases (PubMed, Embase, and Cochrane Library) and ClinicalTrials.gov were systematically searched for randomized placebo-controlled trials (RCTs) of biologic agents from inception to November 15, 2020. The outcomes were the mean change in pain, function scores, and the risk of adverse effects (AEs).
Results
Out of the 28 studies with 29 RCTs (8555 individuals) included, biologic agents were superior to placebo in pain relief (standardized mean difference [SMD] = 0.28, 95% confidence interval [CI] = 0.17–0.38, p < 0.001) and function improvement (SMD = 0.30, 95% CI = 0.18–0.43, p < 0.001). The incidence of any AEs (risk ratio [RR] = 1.09, 95% CI = 1.05–1.14, p < 0.001) and discontinuations due to AEs (RR = 1.39, 95% CI = 1.05–1.83, p = 0.021) were higher following treatment with biologic agents while no significant difference was found in serious AEs. Subgroup analyses showed that NGF inhibitors provided superior pain relief (SMD = 0.36, 95% CI = 0.26–0.47, p < 0.001) and function improvement (SMD = 0.41, 95% CI = 0.30–0.51, p < 0.001), whereas IL-1 inhibitors and TNF-α inhibitors did not. Meanwhile, NGF inhibitors increased the incidence of any AEs (RR = 1.12, 95% CI = 1.07–1.17, p < 0.001) and discontinuations due to AEs (RR = 1.48, 95% CI = 1.07–2.06, p = 0.018). IL-1 inhibitors and TNF-α inhibitors showed no difference in safety compared with placebo.
Conclusions
The efficacy and safety of biologic agents vary by mechanism of action. NGF inhibitors can relieve OA-related pain and improve function but involve safety concerns. IL-1 inhibitors and TNF-α inhibitors are relatively safe options but with limited efficacy.
... More-recent studies linking CCL17 to pain outcomes have focused on its up-regulation following intraplantar GM-CSF injection, in which CCL17 is necessary for GM-CSF-driven inflammatory pain (18). Interestingly, GM-CSF administration was also able to up-regulate the expression of TNF-α and IL-1β, known mediators of inflammatory pain and sensory neuron activation/sensitization (43)(44)(45). On the other hand, our study characterizes the direct contribution of both CCL17 and CCL22 to acute pain. ...
Significance
Interactions between the nervous and immune systems control the generation and maintenance of inflammatory pain. However, the immune cells and mediators controlling this response remain poorly characterized. We identified the cytokines CCL22 and CCL17 as secreted mediators that act directly on sensory neurons to mediate postoperative pain via their shared receptor, CCR4. We also show that skin-resident dendritic cells are key contributors to the inflammatory pain response. Blocking the interaction between these dendritic cell–derived ligands and their receptor can abrogate the pain response, highlighting CCR4 antagonists as potentially effective therapies for postoperative pain. Our findings identify functions for these tissue-resident myeloid cells and uncover mechanisms underlying pain pathophysiology.
... IL-6 is secreted by macrophages and has a determinant role in pain transmission [115,118,119]. IL-8, which is widely distributed among innate immune cells, induces persistent mechanical nociceptor sensitivity in pre-clinical mouse models [120]. G-CSF, macrophage colony-stimulating factor (M-CSF), and GM-CSF are secreted by different cell types, including macrophages, mast cells, and monocytes [121] and are involved in the transmission of inflammatory pain [112,122,123]. ...
Most ocular diseases are associated with pain. While pain has been generally considered a mere (deleterious) additional symptom, it is now emerging that it is a key modulator of innate/adaptive immunity. Because the cornea receives the highest nerve density of the entire body, it is an ideal site to demonstrate interactions between pain and the immune response. Indeed, most neuropeptides involved in pain generation are also potent regulators of innate and adaptive leukocyte physiology. On the other hand, most inflammatory cells can modulate the generation of ocular pain through release of specific mediators (cytokines, chemokines, growth factors, lipid mediators).
This review will discuss the reciprocal role(s) of ocular surface (and specifically: corneal) pain on the immune response of the eye. Finally, we will discuss clinical implications of such reciprocal interactions in the context of highly prevalent corneal diseases.
... It is believed that IL-1β and MMPs could act as possible markers of OA [53,54]. IL-1β was considered as one of the pro-inflammatory cytokines and highly associated with inflammatory pain [55,56]. In the pathological process of OA, the up-regulation of MMPs induced by IL-1β especially MMP-1 and -13, presented as a key event during the irreversible changes of cartilage matrix degradation, for the reason that the type II collagen degeneration and the matrix proteoglycan consequent were released from the cartilage [57,58]. ...
Reactive oxidative stress (ROS) related apoptosis in chondrocytes and extracellular matrix (ECM) degradation play crucial roles in the process of osteoarthritis. Prussian blue nanoparticles are known to scavenge ROS in cellular. Low-intensity pulsed ultrasound has been used as a non-invasive modality for the is widely used in clinical rehabilitation management of OA. In this study, we aim to investigate the effects of PBNPs/LIPUS combined treatment on knee osteoarthritis (KOA) and to determine whether phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway mediates this process. Use LPS to process primary cells of knee joint cartilage to establish a cartilage knee arthritis model. After treated with LIPUS and PBNPs, cell viability was rated by CCK-8 and ROS levels were assessed by DCFH-DA. Articular pathological changes were observed by naked eyes, H&E, and Safranin O staining, then monitored by cartilage lesion grades and Mankin's score. Cellular ROS, apoptosis rate, and TUNEL staining of chondrocytes were fairly decreased in the PBNPs group and the LIPUS group but drastically down-regulated in the PBNPs/LIPUS combination treatment group when compared with the LPS group. Western blot results showed that the cleaved caspase-3, Bax, IL-1β, MMP3 and MMP13 in the PBNPs and LIPUS groups slightly decreased, and Bcl2 increased slightly, while in the combination treatment group, the former was significantly decreased, and Bcl2 was Significantly increased. The PBNPs/LIPUS combination treatment reduced cellular ROS, apoptosis, and matrix metalloproteinases (MMPs), as a consequence, alleviated articular cartilage damage in KOA. Moreover, the PBNPs/LIPUS combination treatment suppressed the JNK/c-Jun signal pathway.
... Another relationship between platelet biology and migraine may be explained by inflammation. Following the formation of platelet-leukocyte aggregates, many pro-inflammatory cytokines, primarily interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor-α, may increase and these mediators may contribute to sterile inflammation and pain facilitation in the brain (19,20,21). A number of studies have been conducted to investigate the potential association between platelet biology and migraine, by the presence of frequent headache attacks mimicking migraine in patients who had essential thrombocytosis and significant contribution of cerebral blood flow abnormalities to the pathogenesis of migraine (18,22,23,24,25,26). ...
Objective: Headache is the most common and challenging neurologic problem in society. There is a relationship between hematologic parameters and headache disorders. White matter lesions are known to be common in migraine. In this study, we aimed to evaluate the hematologic parameters in migraine and tension-type headache, and assessed the correlation of these parameters with headache characteristics and neuroimaging findings.
Materials and Methods: The medical records of patients from the neurology outpatient clinic in Adnan Menderes University Faculty of Medicine between December 1st, 2015, and December 1st, 2016, were retrospectively reviewed. Six hundred thirty-nine patients aged 18-65 years were included. Two hundred seventy-two were diagnosed as having migraine and 323 had tension-type headache according to the IHS 2013 Beta version. The initial hematologic parameters were studied. Patients who had brain magnetic resonance imaging (MRI) were examined separately.
Results: Patients were classified according to their headache types. Age, sex, pain frequency, headache severity, and hematologic parameters were recorded. There was no significant difference between the two groups in terms of hematologic parameters (p>0.05) and there was a negative correlation between pain frequency and headache severity (p
... It is believed that IL-1β and MMPs could act as possible markers of OA [53,54]. IL-1β was considered as one of the pro-in ammatory cytokines and highly associated with in ammatory pain [55,56]. In the pathological process of OA, the up-regulation of MMPs induced by IL-1β especially MMP-1 and − 13, presented as a key event during the irreversible changes of cartilage matrix degradation, for the reason that the type II collagen degeneration and the matrix proteoglycan consequent were released from the cartilage [57,58]. ...
Background: Reactive oxidative stress (ROS) related apoptosis in chondrocytes and extracellular matrix (ECM) degradation play crucial roles in the process of osteoarthritis (OA). Prussian blue nanoparticles (PBNPs) are known to scavenge ROS in cellular. Low-intensity pulsed ultrasound (LIPUS) has been used as a non-invasive modality for the is widely used in clinical rehabilitation management of OA.
Methods: In this study, we aim to investigate the effects of PBNPs/LIPUS combined treatment on knee osteoarthritis (KOA) and to determine whether phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway mediates this process. Use LPS to process primary cells of knee joint cartilage to establish a cartilage knee arthritis model. After treated with LIPUS and PBNPs, cell viability was rated by CCK-8 and ROS levels were assessed by DCFH-DA. Cell apoptosis was estimated by flow cytometry and TUNEL staining. Articular pathological changes were observed by naked eyes, H&E, and Safranin O staining, then monitored by cartilage lesion grades and Mankin’s score. Protein levels of cleaved caspase-3, Bcl-2, Bax, p-PI3K, PI3K, p-Akt, Akt, p-mTOR, mTOR, IL-1β, MMP3, MMP13, p-JINK, JINK, p-c-Jun, and c-Jun were subjected to western blot.
Results: Cellular ROS, apoptosis rate, and TUNEL staining of chondrocytes were fairly decreased in the PBNPs group and the LIPUS group but drastically down-regulated in the PBNPs/LIPUS combination treatment group when compared with the LPS group. Both PBNPs and LIPUS decreased the grades of cartilage lesions and Mankin scores of knee articular cartilage, while combined administration achieved more reduction. Western blot results showed that the cleaved caspase-3, Bax, IL-1β, MMP3 and MMP13 in the PBNPs and LIPUS groups slightly decreased, and Bcl2 increased slightly, while in the combination treatment group, the former was significantly decreased, and Bcl2 was Significantly increased.
Conclusion: The PBNPs/LIPUS combination treatment increased protein levels of p-PI3K, p-Akt, and p-mTOR but decreased the protein levels of p-JINK and p-c-Jun, in vitro and vivo. The PBNPs/LIPUS combination treatment reduced cellular ROS, apoptosis, and matrix metalloproteinases (MMPs), as a consequence, alleviated articular cartilage damage in KOA. Moreover, the PBNPs/LIPUS combination treatment suppressed the JINK/c-Jun signal pathway.
... U937 activated monocytes are able to produce many pro-inflammatory molecules (unpublished data) that, in turn, induce chondrocyte production of inflammatory activators such IL-1β, TNF-α and galectins. IL-1β and TNF-α are considered key pro-inflammatory mediators in OA, since they induce cartilage degradation and are involved in pain generation [36,37]. Therefore, the inhibition of the IL-1β and TNF-α up-regulation could prevent the degradation of joint cartilage during the pathogenesis of OA. ...
The development and progression of osteoarthritis (OA) is associated with macrophage-mediated inflammation that generates a broad spectrum of cytokines and reactive oxygen species (ROS). This study investigates the effects of mid-MW hyaluronic acid (HA) in combination with a lactose-modified chitosan (CTL), on pro-inflammatory molecules and metalloproteinases (MMPs) expression, using an in vitro model of macrophage-mediated inflammation.
Methods:
To assess chondrocyte response to HA and CTL in the presence of macrophage derived inflammatory mediators, cells were exposed to the conditioned medium (CM) of U937 activated monocytes and changes in cell viability, pro-inflammatory mediators and MMPs expression or ROS generation were analysed.
Results:
CTL induced changes in chondrocyte viability that are reduced by the presence of HA. The CM of activated U937 monocytes (macrophages) significantly increased gene expression of pro-inflammatory molecules and MMPs and intracellular ROS generation in human chondrocyte cultures. HA, CTL and their combinations counteracted the oxidative damage and restored gene transcription for IL-1β, TNF-α, Gal-1, MMP-3 and MMP-13 to near baseline values.
Conclusions:
This study suggests that HA-CTL mixture attenuated macrophage-induced inflammation, inhibited MMPs expression and exhibited anti-oxidative effects. This evidence provides an initial step toward the development of an early stage OA therapeutic treatment.
... In rats, several studies of trigeminovascular activation have shown that mast cell degranulation produces long-lasting activation and sensitization of dural nociceptors (Levy et al., 2007). A large number of chemical mediators promote the excitation and sensitization of peripheral nociceptors such as bradykinin, histamine, serotonin, prostaglandin E2 and other inflammatory mediators among which interleukins 1, 6 and 8 and tumour necrosis factor-alpha (Burstein et al., 2011;Sachs et al., 2002). Animal studies implicate CGRP release in the initiation and maintenance of peripheral sensitization (Iyengar et al., 2017) and it has been well documented since 1991 that when CGRP is injected into rats paws, the response threshold to a noxious mechanical stimulus is significantly lowered as a result of peripheral sensitization (Nakamura-Craig et al., 1991). ...
Migraine is a highly prevalent and disabling disorder accounted among the primary headaches. It is the expression of a complex, and not yet fully understood, pathophysiology involving the sensitization of peripheral and central nociceptive pathways. In this review we succinctly illustrate the molecular, anatomical, and functional abnormalities underlying the migraine attack that are relevant for understanding in more depth the neurobiology behind the therapeutic effect of Botulinum Toxin Type A (BoNT-A). BoNT-A has proved effective in several neurological conditions and, more recently, also in chronic migraine. Its antimigraine mechanism of action was initially thought to be limited to the periphery and interpreted as an inhibitory activity on the processes associated to the local release of neuropeptides, with subsequent induction of peripheral sensitization. Increasing experimental evidence has become available to suggest that additional mechanisms are possibly involved, including the direct/indirect inhibition of sensitization processes in central nociceptive pathways.
... Inflammatory mediators have been implicated in the pathophysiology of migraine. [1][2][3][4][5][6][7][8][9][10] Certain nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, diclofenac, ibuprofen, and naproxen, which inhibit the synthesis of prostaglandins by blocking the effects of cyclo-oxygenase (COX)-1 and COX-2 on arachidonic acid, 11 are established as effective for the acute treatment of migraine and are recommended by evidence-based guidelines. 12,13 However, the use of NSAIDs has been associated with an increased risk of adverse gastrointestinal (GI) events that are sometimes serious. ...
Objective:
The objective of this study was to evaluate the efficacy, tolerability, and safety of 120 mg DFN-15 vs placebo for the acute treatment of migraine.
Background:
Certain nonsteroidal anti-inflammatory drugs (NSAIDs) are guideline-recommended therapies for the acute treatment of migraine, but patients who use them may have issues with gastrointestinal tolerability. Celecoxib, a selective inhibitor of cyclooxygenase-2, produces analgesia similar to nonselective NSAIDs. DFN-15 is an oral, ready-made liquid solution of celecoxib being investigated for the acute treatment of migraine.
Methods:
A randomized, double-blind, placebo-controlled, efficacy, tolerability, and safety study in adults with migraine was conducted. Subjects treated a single migraine attack with 120 mg DFN-15 or placebo as soon as possible after the onset of pain of moderate to severe intensity. The 2 independent coprimary efficacy endpoints were the proportion of subjects with freedom from pain and the absence of the most bothersome symptom (MBS) at 2 hours postdose. A second double-blind treatment period followed the first, but did not contribute to the primary outcomes and will be reported elsewhere.
Results:
There were 622 subjects randomized (1:1) to double-blind treatment with either 120 mg DFN-15 or placebo, and 567 (91.2%) treated a migraine with study drug (n = 285 DFN-15; n = 282 placebo). Groups were balanced in demographic characteristics; the mean age was 40, and most subjects were female (87% [494/567]). At 2 hours postdose, DFN-15 was significantly superior to placebo for pain freedom (35.6% [98/275] vs 21.7% [57/263], P < .001), with an odds ratio (95% CI) of 2.00 (1.36, 2.94) and for freedom from the MBS (57.8% [134/232] vs 44.8% [104/232], P = .007), with an odds ratio (95% CI) of 1.68 (1.17, 2.43). A total of 13.3% (38/285) of DFN-15-treated subjects and 8.9% (25/282) of placebo-treated subjects reported a treatment-emergent adverse event (TEAE). Study drug-related TEAEs were reported by 9.1% (26/285) of DFN-15 subjects and 6.0% (17/282) of placebo subjects, the most common of which were dysgeusia (4.2% [12/285] vs 1.4% [4/282]) and nausea (3.2% [9/285] vs 1.8% [5/282]). No subjects treated with DFN-15 reported TEAEs that were severe or led to withdrawal, and no serious TEAEs or deaths were reported in the study.
Conclusions:
DFN-15 was significantly more effective than placebo for the acute treatment of migraine, with a generally favorable tolerability and safety profile.
... Similarly, many kinds of cytokines and chemokines recruit and activate immune cells which produce these mediators, and bronchial epithelial cells can secret different types of cytokines and chemokines to trigger these complex processes as well as some types of phagocytes. As well, continuous increase of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) closely contributes to development of pathological lesions following chronic inflammatory and autoimmune responses (Sachs et al., 2002;Tanaka et al., 2014). IL-8 functions as a neutrophil chemoattractant as well CXCL-1 (Sawant et al., 2016), it can also contribute to the development of autoimmune disease through both recruitment of other types of granulocytes into specific sites and activation and attraction of phagocytes. ...
Methylisothiazolinone (MIT) has been used in wide spectrum of fields due to its ability to inhibit microbial proliferation with low toxicity. Meanwhile, in Korea, the concern about the hazardous effects of MIT was amplified by the occurrence of patients that have humidifier disinfectant-associated pulmonary disease. However, the toxic mechanism for the pathological lesion is still unclear. In our previous study, we identified that cell viability decreased more rapidly in bronchial epithelial cells (BEAS-2B cells) compared to keratinocytes and liver epithelial cells under the same exposure condition. In this study we demonstrated that MIT (2, 4 and 8 μg/mL) induced dose-dependent cytotoxicity 24 h after exposure to BEAS-2B cells. Additionally, MIT impaired structure and function of intracellular organelles via oxidative stress, ultimately leading to apoptotic cell death. We also found notable activation of matrix metalloproteinases (MMPs) and clear aggregation of nucleolus proteins in MIT-treated cells. Furthermore, MIT increased secretion of proinflammatory cytokines (Interleukin (IL)-1β, IL-6, and interferon-γ) and a chemokine (IL-8), and microarray and the KEGG pathway analysis proposed possible carcinogenesis following exposure to MIT. Taken together, we conclude that MIT induces apoptotic cell death and inflammatory response by activating MMPs in BEAS-2B cells. We also suggest that further study is necessary to clarify the possible carcinogenesis of MIT.
... IL-8 was secreted at high levels into the CMs that induced increased capsaicin sensitivity (CM 3 and 4, Fig. 5, Table 1, Supplemental Fig. 5). The receptors for IL-8 are expressed on DRG neurons and regulate the excitability of primary nociceptive neurons 53 and are implicated in chemotherapy induced neuropathic pain 54 , as well as chronic inflammatory pain 55 . IL-8 is involved in long lasting mechanical hypersensitivity that persists even after the inflammatory response has resolved 55 . ...
Schwannomatosis is a multiple tumor syndrome in which patients develop benign tumors along peripheral nerves throughout the body. The first symptom with which schwannomatosis patients often present, prior to discovery of tumors, is pain. This pain can be debilitating and is often inadequately alleviated by pharmacological approaches. Schwannomatosis-associated pain can be localized to the area of a tumor, or widespread. Moreover, not all tumors are painful, and the occurrence of pain is often unrelated to tumor size or location. We speculate that some individual tumors, but not others, secrete factors that act on nearby nerves to augment nociception by producing neuronal sensitization or spontaneous neuronal firing. We created cell lines from human SWN tumors with varying degrees of pain. We have found that conditioned medium (CM) collected from painful SWN tumors, but not that from nonpainful SWN tumors, sensitized DRG neurons, causing increased sensitivity to depolarization by KCl, increased response to noxious TRPV1 and TRPA1 agonists and also upregulated the expression of pain-associated genes in DRG cultures. Multiple cytokines were also detected at higher levels in CM from painful tumors. Taken together our data demonstrate a differential ability of painful versus non-painful human schwannomatosis tumor cells to secrete factors that augment sensory neuron responsiveness, and thus identify a potential determinant of pain heterogeneity in schwannomatosis.
... IL-8 was secreted at high levels into the CMs that induced increased capsaicin sensitivity (CM 3 and 4, Figure 5, Table 1, Supplemental Figure 5). The receptors for IL-8 are expressed on DRG neurons and regulate the excitability of primary nociceptive neurons 53 and are implicated in chemotherapy induced neuropathic pain 54 , as well as chronic inflammatory pain 55 . IL-8 is involved in long lasting mechanical hypersensitivity that persists even after the inflammatory response has resolved 55 . ...
Schwannomatosis is a multiple tumor syndrome in which patients develop benign tumors along peripheral nerves throughout the body. The first symptom with which schwannomatosis patients often present, prior to discovery of tumors, is pain. This pain can be debilitating and is often inadequately alleviated by pharmacological approaches. Schwannomatosis-associated pain can be localized to the area of a tumor, or widespread. Moreover, not all tumors are painful, and the occurrence of pain is often unrelated to tumor size or location. We speculate that some individual tumors, but not others, secrete factors that act on nearby nerves to augment nociception by producing neuronal sensitization or spontaneous neuronal firing. We created cell lines from human SWN tumors with varying degrees of pain. We have found that conditioned medium (CM) collected from painful SWN tumors, but not that from nonpainful SWN tumors, sensitized DRG neurons, causing increased sensitivity to depolarization by KCl, increased response to noxious TRPV1 and TRPA1 agonists and also upregulated the expression of pain-associated genes in DRG cultures. Multiple cytokines were also detected at higher levels in CM from painful tumors. Taken together our data demonstrate a differential ability of painful versus non-painful human schwannomatosis tumor cells to secrete factors that augment sensory neuron responsiveness, and thus identify a potential determinant of pain heterogeneity in schwannomatosis.
... IL-1 amplifies inflammation in OA by inducing other inflammatory mediators (4) and directly contributes to cartilage matrix loss by increasing cartilage catabolism through up-regulation of extracellular proteolytic enzymes while simultaneously suppressing cartilage anabolism through down-regulation of collagen and proteoglycan synthesis (1). IL-1 is also suspected to be one of the key mediators of pain in OA, which is one of the major symptoms and the most common reason for patients to consult a physician (5,6). Therefore, the IL-1 pathway may be an ideal target for OA therapy because blockade of this pathway could potentially be used to both treat symptoms and modify disease. ...
Objective
Gene therapy holds great promise for the treatment of osteoarthritis (OA) because a single intraarticular injection can lead to long‐term expression of therapeutic proteins within the joint. Here we report the development of a helper‐dependent adenovirus (HDAd)‐mediated intraarticular gene therapy approach for long‐term expression of interleukin‐1 receptor antagonist (IL‐1Ra) for sustained symptomatic and disease‐modifying OA therapy.
Methods
In mouse models of OA, efficacy of HDAd‐IL‐1Ra was evaluated by histology, micro‐CT and hot plate analysis. In a horse OA model, safety and efficacy of HDAd‐IL‐1Ra was evaluated by blood chemistry, synovial fluid analysis, gross pathology, lameness, synovial membrane analysis and cartilage analysis.
Results
In skeletally immature mice, HDAd‐IL‐1Ra prevented development of cartilage damage, osteophytes and synovitis. Treatment with HDAd‐IL‐1Ra post‐OA induction resulted in improved ‐ albeit not significant ‐ cartilage status assessed by histology, and significantly increased cartilage volume, cartilage surface and bone surface covered by cartilage assessed by micro‐CT in skeletally immature and mature mice. Fewer osteophytes were observed in HDAd‐IL‐1Ra‐treated skeletally immature mice whereas synovitis was not affected in skeletally immature and mature mice. HDAd‐IL‐1Ra protected from disease‐induced thermal hyperalgesia in skeletally mature mice. In the horse OA model, HDAd‐IL‐1Ra therapy significantly improved lameness parameters indicating efficient symptomatic treatment. Moreover, macroscopic and histologic cartilage and synovial membrane parameters were significantly improved suggesting disease‐modifying efficacy.
Conclusion
These small and large animal data demonstrate safe symptomatic and disease‐modifying treatment with an HDAd expressing IL‐1Ra in relevant OA models. Furthermore, this study establishes HDAd as a vector for joint gene therapy.
This article is protected by copyright. All rights reserved.
... On the contrary, P2Y 12 receptor shRNA treatment inhibited 2-MeSADPinduced [Ca 2+ ] i in these cells. Treatment of the rat paw with TNF-α and IL-1β decreases nociceptive thresholds and produces nociceptive hypersensitivity [11,41]. Treatment with TNF-α and IL-1β can increase intracellular Ca 2+ transients, depolarize membrane potentials, reduce threshold currents for action potentials, and elicit spontaneous firing in DRG neurons [15,42,43]. ...
The direct neurotoxicity of HIV and neurotoxicity of combination antiretroviral therapy medications both contribute to the development of neuropathic pain. Activation of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) plays a crucial role in mechanical and thermal hyperalgesia. The P2Y12 receptor expressed in SGCs of the DRG is involved in pain transmission. In this study, we explored the role of the P2Y12 receptor in neuropathic pain induced by HIV envelope glycoprotein 120 (gp120) combined with ddC (2′,3′-dideoxycytidine). A rat model of gp120+ddC-induced neuropathic pain was used. Peripheral nerve exposure to HIV-gp120+ddC increased mechanical and thermal hyperalgesia in gp120+ddC-treated model rats. The gp120+ddC treatment increased expression of P2Y12 receptor mRNA and protein in DRG SGCs. In primary cultured DRG SGCs treated with gp120+ddC, the levels of [Ca²⁺]i activated by the P2Y12 receptor agonist 2-(Methylthio) adenosine 5′-diphosphate trisodium salt (2-MeSADP) were significantly increased. P2Y12 receptor shRNA treatment inhibited 2-MeSADP-induced [Ca²⁺]i in primary cultured DRG SGCs treated with gp120+ddC. Intrathecal treatment with a shRNA against P2Y12 receptor in DRG SGCs reduced the release of pro-inflammatory cytokines, decreased phosphorylation of p38 MAPK in the DRG of gp120+ddC-treated rats. Thus, downregulating the P2Y12 receptor relieved mechanical and thermal hyperalgesia in gp120+ddC-treated rats.
... In rats subjected to a partial-thickness burn, IL-6 concentrations were elevated at the site of the burn correlating with the duration of pain, and treatment with intradermal anti-IL-6 antibodies significantly reduced pain [167]. In addition, subcutaneous administration of IL-1b, IL-8, and TNF-a result in mechanical and thermal hyperalgesia, suggesting that it is likely that these cytokines contribute to burn injury hyperalgesia [168][169][170]. ...
Objective:
This review aims to examine the available literature on the epidemiology, pathophysiology, and treatment of burn-induced pain.
Methods:
A search was conducted on the epidemiology of burn injury and treatment of burn pain utilizing the database Medline, and all relevant articles were systemically reviewed. In addition, a critical review was performed on the pathophysiology of burn pain and animal models of burn pain.
Results:
The search on the epidemiology of burn injury yielded a total of 163 publications of interest, 72 of which fit the inclusion/exclusion criteria, with no publications providing epidemiological data on burn injury pain management outcomes. The search on the treatment of burn pain yielded a total of 213 publications, 14 of which fit the inclusion/exclusion criteria, highlighting the limited amount of evidence available on the treatment of burn-induced pain.
Conclusions:
The pathophysiology of burn pain is poorly understood, with limited clinical trials available to assess the effectiveness of analgesics in burn patients. Further studies are needed to identify new pharmacological targets and treatments for the effective management of burn injury pain.
... This vasodilation can in turn foster the initiation, promotion and/or aggravation of migraine attacks (302,349). IL-1, IL-6 and IL-8 and their receptors are present at different brain structures, where they appear to be fundamental for the correct functioning of synaptic connections that contribute to brain development and plasticity (37) and can promote excitation and sensitization of nociceptors through the endogenous release of eicosanoids and sympathetic amines (48, 305). ...
Significance:
Migraine represents the third most prevalent and the seventh most disabling human disorder. Approximately 30% of migraine patients experience transient, fully reversible, focal neurological symptoms (aura) preceding the attack. Recent Advances: Awareness of the hypothesis that migraine actually embodies a spectrum of illnesses-ranging from episodic to chronic forms-is progressively increasing and poses novel challenges for clarifying the underlying pathophysiological mechanisms of migraine as well as for the development of novel therapeutic interventions. Several theories have evolved to the current concept that a combination of genetic, epigenetic, and environmental factors may play a role in migraine pathogenesis, although their relative importance is still being debated.
Critical issues:
One critical issue that deserves a particular attention is the role of oxidative stress in migraine. Indeed, potentially harmful oxidative events occur during the migraine attack and long-lasting or frequent migraine episodes may increase brain exposure to oxidative events that can lead to chronic transformation. Moreover, a wide variety of dietary, environmental, physiological, behavioral, and pharmacological migraine triggers may act through oxidative stress, with clear implications for migraine treatment and prophylaxis. Interestingly, almost all current prophylactic migraine agents exert antioxidant effects.
Future directions:
Increasing awareness of the role of oxidative stress and/or decreased antioxidant defenses in migraine pathogenesis and progression to a chronic condition lays the foundations for the design of novel prophylactic approaches, which, by reducing brain oxidative phenomena, could favorably modify the clinical course of migraine. Antioxid. Redox Signal. 00, 000-000.
... 7 PPSP is a complex condition in which inflammatory, nociceptive and neuropathic components are involved. 8 Its incidence varies widely, according to the type of surgery, and after TKA it ranges between 20 and 50% at 1 year. 9,10 Given the number of TKA performed every year 11 a large number of individuals must be affected. ...
Background:
Perioperative regional anaesthesia may protect from persistent postsurgical pain (PPSP) and improve outcome after total knee arthroplasty (TKA).
Objectives:
Aim of this study was to evaluate the impact of regional anaesthesia on PPSP and long-term functional outcome after TKA.
Design:
A web-based prospective observational registry.
Setting:
Five Italian Private and University Hospitals from 2012 to 2015.
Patients:
Undergoing primary unilateral TKA, aged more than 18 years, informed consent, American Society of Anesthesiologists (ASA) physical status classes 1 to 3, no previous knee surgery.
Intervention(s):
Personal data (age, sex, BMI and ASA class), preoperative pain assessed by numerical rating scale (NRS) score, and risk factors for PPSP were registered preoperatively. Data on anaesthetic and analgesic techniques were collected. Postoperative pain (NRS), analgesic consumption, major complications and patient satisfaction were registered up to the time of discharge. PPSP was assessed by a blinded investigator during a phone call after 1, 3 and 6 months, together with patient satisfaction, quality of life (QOL) and walking ability.
Main outcome measures:
Experience of PPSP according to the type of peri-operative analgesia.
Results:
Five hundred sixty-three patients completed the follow-up. At 6 months, 21.6% of patients experienced PPSP, whereas autonomy was improved only in 56.3%; QOL was worsened or unchanged in 30.7% of patients and improved in 69.3%. Patients receiving continuous regional anaesthesia (epidural or peripheral nerve block) showed a lower NRS through the whole peri-operative period up to 1 month compared with both single shot peripheral nerve block and those who did not receive any type of regional anaesthesia. No difference was found between these latter two groups. Differences in PPSP at 3 or 6 months were not significantly affected by the type of anaesthesia or postoperative analgesia. A higher NRS score at 1 month, younger age, history of anxiety or depression, pro-inflammatory status, higher BMI and a lower ASA physical status were associated with a higher incidence of PPSP and worsened QOL at 6 months.
Conclusion:
Continuous regional anaesthesia provides analgesic benefit for up to 1 month after surgery, but did not influence PPSP at 6 months. Better pain control at 1 month was associated with reduced PPSP. Patients with higher expectations from surgery, enhanced basal inflammation and a pessimistic outlook are more prone to develop PPSP.
Trial registration:
Clinicaltrials.gov identifier: NCT02147730This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0.
... In various models of neuropathic pain, glial activation has been reported to contribute to neuropathic pain by releasing pro-inflammatory cytokines [30]. Once activated after peripheral nerve injury, glia cells such as astrocytes and microglia can release a plethora of pro-inflammatory mediators such as IL-1β and TNF [31,32] involved in the process of nociceptor hypersensitivity [33]. In an injured sciatic nerve animal model, mRNA and protein levels of IL-1β and TNF are rapidly up-regulated, and mice lacking both IL-1 type 1 receptor and TNF type 1 receptor have lower nociceptive sensitivity compared to wild-type littermates after injury [34]. ...
Oxaliplatin, a chemotherapy drug, induces acute peripheral neuropathy characterized by cold allodynia, spinal glial activation and increased levels of pro-inflammatory cytokines. Herein, we determined whether Cinnamomi Cortex (C. Cortex), a widely used medicinal herb in East Asia for cold-related diseases, could attenuate oxaliplatin-induced cold allodynia in rats and the mechanisms involved. A single oxaliplatin injection (6 mg/kg, i.p.) induced significant cold allodynia signs based on tail immersion tests using cold water (4°C). Daily oral administration of water extract of C. Cortex (WECC) (100, 200, and 400 mg/kg) for five consecutive days following an oxaliplatin injection dose-dependently alleviated cold allodynia with only a slight difference in efficacies between the middle dose at 200 mg/kg and the highest dose at 400 mg/kg. WECC at 200 mg/kg significantly suppressed the activation of astrocytes and microglia and decreased the expression levels of IL-1β and TNF in the spinal cord after injection with oxaliplatin. Furthermore, oral administration of coumarin (10 mg/kg), a major phytocompound of C. Cortex, markedly reduced cold allodynia. These results indicate that C. Cortex has a potent anti-allodynic effect in oxaliplatin-injected rats through inhibiting spinal glial cells and pro-inflammatory cytokines. We also suggest that coumarin might play a role in the anti-allodynic effect of C. Cortex.
... 37,38 Inflammation eventually lead to increased endogenous eicosanoid, including prostaglandin E 2 . 39,40 Increased PGE 2 levels 7 days postoperatively in the LF group showed that there was an increased of pain mediators due to greater inflammation prolong the pain after surgery. ...
Objective: Modified Fenestration-Restorative Spinoplasty (MFRS) technique is an alternative to lumbar stenosis treatment, providing the equal decompression comparing with laminectomy techniques, without the implant, less expensive and complication rates. The purpose of this study was to determine which technique gives better inflammation and clinical outcome based on high sensitive C-Reactive Protein biomarker (hsCRP) and Prostaglandin E2 (PGE
2), Visual Analog Scale (VAS) of the day 7th postsurgery and ODI scores 3rd month post surgery.
Methods: This study design is an experimental pretest-posttest randomized control group design.
Results: This study results showed that the mean levels of hsCRP day 7th postsurgery were differ significantly between MFRS (23,09 ± 15,3 mg/L) compared to LF (39,53 ± 24,4 mg/L). Likewise for the mean levels of PGE2 day 7th postsurgery were differ significantly between MFRS (491,39 ± 528,5 pg/ml) compared to LF (1103,7 ± 1033,6 pg/ml) at the significance level of p
... Particularly, IL-1 is identified as a key target as it induces production of free radicals and MMPs 6,7 and is also involved in transmission of pain. 8 Interleukin 1 receptor antagonist (IL-1Ra) is a naturally occurring IL-1 inhibitor that binds to the IL-1 receptor (IL-1R) without triggering an agonist response and thus functions as a receptor antagonist. 9 As such, IL-1Ra has been explored as a therapy to treat OA via local delivery of bolus protein injections 9-12 and gene therapy approaches. ...
Osteoarthritis is a progressive joint disease that results in degradation of cartilage in load-bearing joints. Pain and inflammation in the joint are hallmarks of this condition which further exacerbate the cartilage destruction and health of the patient. It is hence imperative to treat the joint inflammation at the earliest. Interleukin 1 (IL-1) blockade by IL-1 receptor antagonist (IL-1Ra) has shown promise in the clinic but this therapy suffers from rapid clearance, high doses and frequent intervention. Use of carrier particles that result in longer residence time has been proposed. Here we have synthesized a new class of nanoparticles presenting IL-1Ra on the surface and with tunable size from 300 to 700 nm. These IL-1Ra-poly(2-hydroxyethyl methacrylate)-pyridine nanoparticles are cytocompatible and stable in serum-containing solutions for several days. Our results further demonstrate that these nanoparticles are capable of blocking IL-1β signaling in a NF-κB inducible reporter cell line. These engineered nanoparticles are promising for localized intra-articular delivery in joint space to reduce inflammation in osteoarthritis and other inflammatory diseases. This article is protected by copyright. All rights reserved.
The altered activity generated by corneal neuronal injury can result in morphological and physiological changes in the architecture of synaptic connections in the nervous system. These changes can alter the sensitivity of neurons (both second-order and higher-order projection) projecting pain signals. A complex process involving different cell types, molecules, nerves, dendritic cells, neurokines, neuropeptides, and axon guidance molecules causes a high level of sensory rearrangement, which is germane to all the phases in the pathomechanism of corneal neuropathic pain. Immune cells migrating to the region of nerve injury assist in pain generation by secreting neurokines that ensure nerve depolarization. Furthermore, excitability in the central pain pathway is perpetuated by local activation of microglia in the trigeminal ganglion and alterations of the descending inhibitory modulation for corneal pain arriving from central nervous system. Corneal neuropathic pain may be facilitated by dysfunctional structures in the central somatosensory nervous system due to a lesion, altered synaptogenesis, or genetic abnormality. Understanding these important pathways will provide novel therapeutic insight.
Inflammation is the consequence of dry eye disease regardless of its etiology. Several injurious or harmless processes to the ocular surface neurons promote ocular surface neurogenic inflammation, leading to the vicious cycle of dry eye disease. These processes include the regular release of neuromediators during the conduction of ocular surface sensations, hyperosmolarity-induced ocular surface neuronal damage, neuro-regenerative activities, and neuronal-mediated dendritic cell activities. Neurogenic inflammation appears to be the main culprit, instigating the self-perpetuating inflammation observed in patients with dry eye disease.
Objective
Metabolic dysfunction can cause IL-1β mediated activation of the innate immune system, which could have important implications for the therapeutic efficacy of IL-1β neutralizing drugs as treatment for OA in the context of metabolic syndrome (MetS). In the present study, we investigated whether early treatment with a single dose of IL-1β blocking antibodies could prevent Western diet (WD) induced changes to systemic monocyte populations and their cytokine secretion profile and herewith modulate collagenase induced osteoarthritis (CiOA) pathology.
Methods
CiOA was induced in female C57Bl/6 mice fed either a standard diet (SD) or WD and treated with a single dose of either polyclonal anti-IL-1β antibodies or control. Monocyte subsets and granulocytes in bone marrow and blood were analyzed with flow cytometry, and cytokine expression by bone marrow cells was analyzed using qPCR. Synovial cellularity, cartilage damage and osteophyte formation were assessed on histology.
Results
WD feeding of C57Bl/6 mice led to increased serum levels of low-density lipoprotein (LDL) and innate immune activation in the form of an increased number of Ly6Chigh cells in bone marrow and blood and increased cytokine expression of especially IL-6 and TNF-α by bone marrow cells. The increase in monocyte number and activity was ameliorated by anti-IL-1β treatment. However, anti-IL-1β treatment did not significantly affect synovial lining thickness, cartilage damage and osteophyte formation during WD feeding.
Conclusions
Single-dose systemic anti-IL-1β treatment prevented WD-induced innate immune activation during early stage CiOA in C57Bl/6 mice, but did not ameliorate joint pathology.
Background:
The purpose of this prospective study was to compare the changes in periodontal somatosensory function and microcirculation in patients with periodontitis following initial treatment with scaling and root planing (SRP) with or without adjuvant laser therapy.
Methods:
Twenty-four patients suffering from periodontitis were recruited and randomly allocated into a split-mouth design to either SRP combined laser therapy side (test side) or SRP only side (control side). All treatments were performed by the same investigator at a single visit. Laser Doppler Flowmetry (LDF) and Quantitative Sensory Testing (QST) were performed at baseline (W0), 1 week (1W), 2 weeks (2W), and 4 weeks (4W) after treatment on both sides of the attached gingiva of the maxillary lateral incisor. Clinical examination including pocket probing depth (PPD) and bleeding on probing (BOP) was performed at W0, 2W, and 4W on both sides. Data were analyzed with two-way analysis of variance (ANOVA).
Results:
The PPD and BOP significantly improved after treatment (P <0.001). The LDF values were significantly decreased on both sides at all follow-up time points (P <0.001), temperature was increased only on the test side (P = 0.017) whereas there was no significant change on the control side (P = 0.792). Significantly less sensitivity was observed for all QST parameters (P <0.030) except for warmth detection after treatment.
Conclusion:
Adjunctive use of laser therapy did not provide any significant clinically advantage or additional effects on the recovery of periodontal somatosensory function or gingival microcirculation in the present study. This article is protected by copyright. All rights reserved.
Pregnancy can be seen as a positive time for women migraineurs because the elevated estrogen and endogenous opioid levels raise the pain threshold and the stable hormone levels, which no longer fluctuate, eliminate a major trigger factor for the attacks. In a great majority of cases, indeed, migraine symptoms spontaneously improve throughout pregnancy. Generally, migraine without aura (MO) improves better than migraine with aura (MA), which can occur ex novo in pregnancy more frequently than MO. After childbirth, the recurrence rate of migraine attacks increases, especially during the first month; breastfeeding exerts a protective effect against the reappearance of attacks. Migraine and pregnancy share a condition of hypercoagulability; therefore, attention must be paid to the risk of cardiovascular disorders, like venous thromboembolism and ischemic or hemorrhagic strokes. Some of these diseases can be linked to preeclampsia (PE), a serious complication of pregnancy, characterized by hypertension, proteinuria, or other findings of organ failure. This condition is more common in migraineurs compared with non-migraineurs; furthermore, women whose migraines worsen during pregnancy had a 13-fold higher risk of hypertensive disorders than those in which migraine remitted or improved. Pregnancy is generally recognized to exert a beneficial effect on migraine; nonetheless, clinicians should be on the alert for possible cardiovascular complications that appear to be more frequent in this patient population.
Background:
Gabapentin, as a structural analogue of γ-aminobutyric acid, has been investigated to provide pain relief in the early postoperative period following various surgical interventions.
Objectives:
The objective of this study was to investigate whether preemptive oral administration of gabapentin 800 mg can reduce postoperative pain and modulate the inflammatory cytokine response in comparison to placebo in patients undergoing total knee arthroplasty under general anesthesia.
Material and methods:
Fifty-two patients were randomly divided into 2 groups before surgery, either to receive peroral gabapentin 800 mg or placebo drug, 1 h before surgery. All patients had general anesthesia with endotracheal intubation, in a standardized fashion, by the same anesthetist. Thirty min before completion of surgery, intramuscular diclofenac sodium 75 mg was administered. Following extubation, visual analogue pain scale (VAS) scores and additional analgesic requirements were recorded at 15 min at post-anesthesia care unit (PACU), and at 4th and 24th h postoperatively. Plasma levels of interleukin 6 (IL-6), and tumor necrosis factor R (TNF-R) were measured at predetermined time points (T0 1 h before administration of gabapentin, T1 at postoperative the 4th h mark, and T2 at postoperative at the 24th h mark).
Results:
The VAS scores at postoperative 4th h were significantly higher in placebo and gabapentin groups compared with VAS scores at PACU and at 24th h. The groups did not differ in terms of additional analgesic requirements. In gabapentin group, IL-6 levels at T1 and T2 were significantly lower in comparison to values measured in placebo group at the same time points. This difference was not significant in TNF-R levels between the groups.
Conclusions:
Though preemptive oral gabapentin administration did not reduce postoperative pain and analgesic requirements in total knee arthroplasty surgery, it attenuated IL-6 production on the first postoperative day.
Human immunodeficiency virus (HIV) envelope glycoprotein (glycoprotein 120, gp120) can induce chronic neuropathic pain by directly stimulating primary sensory afferent neurons. Activation of satellite glial cells (SGCs) in dorsal root ganglia (DRG) plays an important role in the transmission of neuropathic pain. The P2Y12 receptor is expressed in SGCs of DRG. In this study, we investigated the role of the P2Y12 receptor in HIV gp120-induced neuropathic pain. The results showed that peripheral nerve exposure to HIV gp120 increased mechanical and thermal hyperalgesia in gp120-treated model rats. The gp120 treatment increased the expression of P2Y12 mRNA and protein in DRG SGCs. Treatment with P2Y12 short hairpin RNA (shRNA) in DRG SGCs decreased the upregulated expression of P2Y12 mRNA and protein in DRG SGCs as well as relieved mechanical and thermal hyperalgesia in gp120-treated rats. Reduction of P2Y12 receptor decreased co-expression of P2Y12 and glial fibrillary acidic protein (GFAP), expression of GFAP, interleukin (IL)-1β, tumor necrosis factor (TNF)-receptor 1 (TNF-R1), and phosphorylation of Akt (p-Akt) proteins in DRG of gp120-treated rats. Upregulation of GFAP is a marker of SGC activation. Therefore, P2Y12 shRNA treatment decreased HIV gp120-induced mechanical and thermal hyperalgesia in gp120-treated rats.
We found that the coagulation and cytokine pathways were important mechanisms involve in the degeneration of intervertebral discs (IVD) using a microarray approach to analyze gene expression in different grades of specimens. Furthermore, using a cytokine/chemokine array, a significant increase in CXCL8 expression was observed in human nucleus pulposus (NP) cells after thrombin treatment. The enhancement of CXCL8 expression by thrombin was activated by the PAR1 receptor. Importantly, analysis of degenerated human NP tissue samples showed that EGFR expression positively correlated with the grade of tissue degeneration. In NP cells, thrombin caused an increase in phosphorylation of the EGFR at the Tyr1068, and treatment with the pharmacological EGFR inhibitor, AG1473 effectively blocked thrombin-enhanced CXCL8 production. Surprisingly, inhibition of STAT3 for 24 h decreased expression of EGFR. Treatment with thrombin also increased Akt and GSK3α/β activation; this activation was also blocked by EGFR inhibitor. Although c-Src, ERK, and FAK were activated by thrombin, only c-Src and ERK were involved in the STAT3/CXCL8 induction. Our findings indicate that stimulation of an inflammatory response in NP cells by thrombin is part of a specific pathophysiology that modulates the EGFR activation through activation of Src/ERK/STAT3 signaling.
Interleukin-8 (IL-8) is a pro-inflammatory cytokine that has been shown to play a role in inflammatory and autoimmune disorders. The objective of the present study was to assess the levels of IL-8 in rat serum, dorsal root ganglion (DRG) and the sciatic nerve following four different forms of sciatic nerve injury. The models used to induce the injury included partial sciatic ligation (PSL), chronic constriction injury (CCI), perineural inflammation (neuritis) and complete sciatic transection (CST). Mechanical and thermal hyperalgesia were detected by measuring withdrawal responses from a mechanical stimulus and withdrawal latency from thermal stimulation. Enzyme-linked immunosorbent assays (ELISA) was used to assess the IL-8 levels in the affected and contralateral sciatic nerves. Rats exposed to PSL and neuritis developed significant nociceptive response (mechanical and thermal hyperalgesia) in the affected side at three days post-surgery whereas the CCI group at eight days post-surgery. No mechanical or thermal hyperalgesia was observed in rats exposed to CST at either three or eight days postsurgery. Additionally, IL-8 levels were significantly increased in the injured sciatic nerve at 3 and 8 days following PSL and neuritis as well as at 8 days following CCI when compared to naïve animals. A significant up regulation of IL-8 levels was observed in the ipsilateral DRG at 3 and 8 days following CST compared to naïve animals. The serum IL-8 levels remained unchanged in all models of nerve damage. The results of this study suggest that IL-8's role in the neuropathic pain etiology may be specific to nerve injury type.
Inflammatory and neurotrophic factors are involved in postherpetic neuralgia (PHN), but the association of these factors in the cerebrospinal fluid (CSF) with the level of pain is poorly known. The present study aimed to examine the changes in neurotrophic and inflammatory factors in the CSF of patients with PHN and to study the correlation between these factors and the degree of pain. Fifty patients with PHN and 28 patients with hemifacial spasm (as controls) were recruited between May 2015 and March 2016. CSF levels of inflammatory and neurotrophic factors were measured by ELISA. Compared with controls, patients with PHN had lower CSF levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin (NT)-3, NT-5, and P substance (all P < 0.05), and higher CSF levels of interleukin (IL)-1β (P = 0.050). Among patients with PHN, CSF BDNF levels were positively correlated to IL-8 (rs = 0.229, P = 0.04); glial cell line-derived neurotrophic factor (GDNF) levels to IL-8 (rs = 0.326, P = 0.004) levels; NGF levels to tumor necrosis factor (TNF)-α levels (rs = 0.229, P = 0.044); NT-3 levels to IL-1β (rs = 0.228, P = 0.045); and NT-5 levels to IL-8 (rs = 0.388, P < 0.001), and TNF-α (rs = 0.445, P < 0.001) levels. Inflammatory and neurotrophic factors were not correlated with the visual analog scale score and von Frey. Multivariable linear regression showed PHN was associated with NGF (P = 0.038) and BDNF (P = 0.029), independently from age and major medical history. In conclusion, patients with PHN showed low levels of BDNF, NGF, NT-3, and NT-5. Among patients with PHN, CSF levels of neurotrophic factors positively correlated with inflammatory factors.
El dolor es una senal de alarma no solo para la lesion nerviosa o tisular focal sino tambien como un indicador de enfermedad sistemica. Los signos generados por los sistemas autonomo, endocrino y autoinmunitario, coordinados a traves de los circuitos del sistema nervioso central (SNC), producen cambios que son percibidos como dolor, y la falta de regulacion de estas vias de senales bidireccionales puede contribuir a generalizar los sindromes dolorosos y los sintomas de la enfermedad. Este capitulo resume la comunicacion bidireccional entre los circuitos del SNC y los sistemas autonomo, endocrino e inmunitario que se encuentran involucrados en las defensas del huesped, lo cual tambien contribuye al aumento de la sensacion dolorosa. Estas interacciones son: • La senalizacion desde el sistema inmunitario al SNC a traves de diferentes ramas subdiafragmaticas del nervio vago, para inducir los sintomas de la enfermedad.
L’arthrose est de loin la plus fréquente des affections rhumatologiques. Elle affecte, audelà de 55 ans, plus de 50 % de la population. Il ne s’agit pas seulement d’une maladie du cartilage. Il existe en effet une inflammation précoce de la membrane synoviale, un renouvellement accéléré de l’os sous-chondral, mais également des modifi cations des structures para-articulaires qui jouent un role important dans l’évolution de la maladie.
Purpose of review When tissue is destroyed, pain arises. Tissue destruction is associated with an inflammatory reaction. This leads to activation of nociceptors. The following review will concentrate on pro-algesic and analgesic mediators, which arise from immune cells or resident cells in the periphery or the circulation during inflammation. Recent findings In early inflammation endogenous hyperalgesic mediators are produced, including cytokines, chemokines, nerve growth factor as well as bradykinin, prostaglandins and ATP. Simultaneously, analgesic mediators are secreted: opioid peptides, somatostatin, endocannabinoids and certain cytokines. Inflammation increases the expression of peripheral opioid receptors on sensory nerve terminals and enhances their signal transduction, as well as the amount of opioid peptides in infiltrating immune cells. Interference with the recruitment of opioid-containing immune cells into inflamed tissue by blockade of adhesion molecules or by intrathecal morphine injection reduces endogenous analgesia. Summary Inflammatory pain is the result of the interplay between pro-algesic and analgesic mediators. To avoid central side effects, future analgesic therapy should be targeted at either selectively blocking novel pro-algesic mediators or at enhancing endogenous peripheral analgesic effects.
When tissue is destroyed or invaded by immune cells in inflammation, numerous mediators are liberated at the site. Proalgesic mediators include proinflammatory cytokines, chemokines, nerve growth factor, prostaglandins, and sympathetic amines, which are produced by invading immune cells or by resident cells. They will be discussed in Proalgesic Mechanisms. Other mediators arise from cell destruction (e.g., hydrogen ions) or are formed in the circulation (bradykinin). Bradykinin is one of the best-studied peripheral proalgesic mediator and will be described shortly in Other Mediators: Bradykinin. Less well-known is that analgesic mediators which counteract pain are also produced in inflamed tissue as described in Analgesic Mechanisms. These include anti-inflammatory cytokines, somatostatin, endocannabinoids, and opioid peptides. As opioid peptides have been characterized most extensively, they will be discussed in more depth (Opioid Peptides).
Oxysophocarpine is an alkaloid extracted from Sophora alopecuroides. We investigated the analgesic effect of oxysophocarpine on carrageenan-induced inflammatory pain in mice, in order to explore its possible mechanisms. Mouse ear swelling tests and carrageenan-induced paw edema tests were used to investigate the effects of oxysophocarpine on inflammatory pain in mice. Morphological changes on inflamed paw sections were measured by hematoxylin-eosin staining. The mRNA and protein expression of extracellular signal-regulated kinase, phosphorylation of extracellular signal-regulated kinase 1/2, cyclooxygenase-2, tumor necrosis factor α, interleukin-1 beta, interleukin-6 and prostaglandin E2 were investigated by real-time quantitative polymerase chain reaction, immunohistochemistry, western-blot and enzyme-linked immunosorbent assay. In our results, oxysophocarpine shows a significant anti-inflammatory effect in the mouse ear swelling test. Oxysophocarpine also significantly reduced the paw edema volume and improved mechanical allodynia threshold value on carrageenan-induced inflammatory pain, as well as relieved paw tissues inflammatory damage and reduced the numbers of neutrophils in mice. Oxysophocarpine significantly suppressed over-expression of cyclooxygenase-2, tumor necrosis factor α, interleukin-1 beta, interleukin-6 and prostaglandin E2, and inhibited the over-phosphorylation of extracellular signal-regulated kinase 1/2. Based on these findings we propose that oxysophocarpine attenuates inflammatory pain by suppressing the levels of phosphorylation of extracellular signal-regulated kinase 1/2, cyclooxygenase-2, prostaglandin E2, tumor necrosis factor α, interleukin-1 beta and interleukin-6.
Georg Thieme Verlag KG Stuttgart · New York.
Multiple lines of evidence support the notion that much if not most chronic pain is dependent on on-going peripheral activity in nociceptors. This is not to say that central changes are unimportant, only that much of the central change is supported by a peripheral drive. This begs the question of what causes this peripheral drive. In some instances, particularly in association with peripheral nerve injury, nociceptors may become spontaneously active because of alterations in ion channel function or expression. But in most cases nociceptor activity arises because of the actions of peripheral mediators released by injured or damaged tissue. Some of these mediators are well known, such as the prostanoids. Others have more recently been identified, such as nerve growth factor (NGF). However, the limited efficacy of existing analgesic therapies strongly suggests that other important pain mediators exist. Here we discuss the evidence that a family of secreted proteins, the chemokines – well known for their actions in regulating immune cell migration – also play an important role in sustaining abnormal nociceptor activity in persistent pain states.
The pathophysiology of chronic inflammatory pain remains poorly understood. In this context, we developed an experimental model in which successive daily injection of prostaglandin E2 (PGE2) for 14 days into rat hind paws produces a persistent state of hypernociception (i.e. decrease in mechanical nociceptive threshold). This state persists for more than 30 days after discontinuing PGE2 injection. In the present study, we investigated the participation of nuclear factor kappa B (NF-κB), in the maintenance of this process. Mechanical hypernociception was evaluated using the electronic von Frey test. Activation of NF-κB signaling was measured through the determination of NF-κB p65 subunit translocation to the nucleus of dorsal root ganglion neurons (DRG) by immunofluorescence and western blotting. Herein, we detected an increase in NF-κB p65 subunit translocation to the nucleus of DRG neurons along with persistent inflammatory hypernociception compared with controls. Intrathecal treatment with either dexamethasone or PDTC (NF-κB activation inhibitor) after ending of the induction phase of the persistent inflammatory hypernociception, curtailed the hypernociception period as well as reducing NF-κB p65 subunit translocation. Treatment with antisense oligonucleotides against the NF-κB p65 subunit for 5 consecutive days also reduced persistent inflammatory hypernociception. Inhibition of PKA and PKCε reduced persistent inflammatory hypernociception, which was associated with inhibition of NF-κB p65 subunit translocation. Together these results suggest that peripheral activation of NF-κB by PKA and PKC in primary sensory neurons plays an important role in maintaining persistent inflammatory pain.
Human recombinant interleukin 1 alpha (IL-1 alpha) and IL-1 beta stimulated prostaglandin E2 synthesis in 3T3 fibroblasts in a time- and concentration-dependent manner. Enhanced prostaglandin E2 synthesis after IL-1 treatment was apparent by 1 hr and continued to increase for at least 2 days. Half-maximal stimulation occurred at 0.5 pM IL-1 alpha or IL-1 beta, and both interleukins were equally effective, with maximal stimulation occurring in response to 5-10 pM IL-1. In contrast to IL-1, bradykinin stimulation of prostaglandin E2 synthesis is rapid; its effect is maximal by 5 min. In cells that had been pretreated with IL-1 for 24 hr, prostaglandin E2 synthesis in response to bradykinin was amplified more than 10-fold. IL-1 also amplified the receptor-mediated formation of prostaglandin E2 by bombesin and thrombin. The lymphokine did not affect bradykinin receptor number or affinity. IL-1 treatment induced phospholipase A2 and cyclooxygenase but not phospholipase C or prostaglandin E isomerase. It also enhanced bradykinin-stimulated GTPase activity, suggesting possible induction of the GTP-binding regulatory protein coupled to the bradykinin receptor. Thus, IL-1 enhanced receptor-mediated release of prostaglandin E2 in response to bradykinin, bombesin, and thrombin by increasing the cellular levels of phospholipase A2, cyclooxygenase, and GTP-binding regulatory protein(s).
1. Peripheral inflammation is associated with the local production of neuroactive inflammatory cytokines and growth factors. These may contribute to inflammatory pain and hyperalgesia by directly or indirectly altering the function or chemical phenotype of responsive primary sensory neurones. 2. To investigate this, inflammation was produced by the intraplantar injection of complete Freund's adjuvant (CFA) in adult rats. This resulted in a significant elevation in interleukin-1 beta (IL-1 beta) and nerve growth factor (NGF) levels in the inflamed tissue and of the peptides, substance P and calcitonin gene-related peptide (CGRP) in the L4 dorsal root ganglion 48 h post CFA injection. 3. The effects of a steroidal (dexamethasone) and a non-steroidal (indomethacin) anti-inflammatory drug on the levels of NGF and IL-1 beta in inflamed tissue were investigated and compared with alterations in behavioural hyperalgesia and neuropeptide expression in sensory neurones. 4. Systemic dexamethasone (120 micrograms kg-1 per day starting the day before the CFA injection) had no effect on the inflammatory hyperalgesia. When the dose was administered 3 times daily, a reduction in mechanical and to a lesser extent thermal sensitivity occurred. Indomethacin at 2 mg kg-1 daily (i.p.) had no effect on the hyperalgesia and a dose of 4 mg kg-1 daily was required to reduce significantly mechanical and thermal hypersensitivity. 5. The increase in NGF produced by the CFA inflammation was prevented by both dexamethasone and indomethacin, but only at the higher dose levels. Dexamethasone at the lower and higher dose regimes diminished the upregulation of IL-1 beta whereas indomethacin had an effect only at the higher dose. 6. The increase in SP and CGRP levels produced by the CFA inflammation was prevented by dexamethasone and indomethacin at the lower and higher dose regimes. 7. Intraplantar injections of IL-1 beta (0.01, 0.1 and 1 ng) produced a brief (6 h) thermal hyperalgesia and an elevation in cutaneous NGF levels which was prevented by pretreatment with human recombinant IL-1 receptor antagonist (IL-1 ra) (0.625 microgram, i.v.). The thermal hyperalgesia but not the NGF elevation produced by intraplantar IL-1 beta (1 ng) was prevented by administration of a polyclonal neutralizing anti-NGF serum. 8. IL-1 ra significantly reduced the mechanical hyperalgesia produced by CFA for 6 h after administration as well as the CFA-induced elevation in NGF levels. Anti-NGF pretreatment substantially reduced CFA-induced mechanical and thermal hyperalgesia without reducing the elevation in IL-1 beta. 9. Intraplantar NGF (0.02, 0.2 and 2 microg) injections produced a short lasting thermal and mechanical hyperalgesia but did not change IL-1beta levels in the hindpaw skin.10. Our results demonstrate that IL-1beta contributes to the upregulation of NGF during inflammation and that NGF has a major role in the production of inflammatory pain hypersensitivity.
This study analyzes cyclooxygenase II (COX-2) gene expression, protein synthesis, and PGE2 release in normal human articular chondrocytes. Stimulation of chondrocytes in primary culture resulted in a dose-dependent induction of COX-2 mRNA in response to IL-1 with an ED50 between 0.1 and 1 ng/ml. COX-2 mRNA was detectable after 2 h, reached high levels at 6 h, and showed a remarkably long duration of expression for at least 72 h. Analysis of other extracellular stimuli showed that COX-2 mRNA was inducible by other cytokines including TNF-alpha, IL-6, and LIF and by bacterial LPS. Dexamethasone completely inhibited IL-1-induced COX-2 mRNA expression. Analysis of signaling pathways showed that PMA and calcium ionophore A23187, but not dibutyryl cAMP, induced COX-2 mRNA. The combination of IL-1 and A23187 resulted in synergistic increases. IL-1 effects were not reduced by the protein kinase C inhibitor staurosporine or by the protein kinase A inhibitor H89 but blocked by the protein tyrosine kinase inhibitor herbimycin A. COX-2 protein was detected at 71 kDa by Western blotting in IL-1-stimulated, and to almost similar levels in A23187-treated, cells. Flow cytometric analysis showed that after IL-1 stimulation 78% of the chondrocytes expressed COX-2 protein. The patterns of COX-2 protein expression and the levels of PGE2 release correlated with the effects of the different stimuli and inhibitors on mRNA expression.
The pleiotropic cytokine tumor necrosis factor-alpha (TNFalpha) is implicated in the development of persistent pain through its actions in the periphery and in the central nervous system (CNS). Activation of the alpha(2)-adrenergic receptor is associated with modulation of pain, possibly through its autoregulatory effect on norepinephrine (NE) release in the CNS. The present study employs a chronic constriction nerve injury (CCI) pain model to demonstrate the interactive role of presynaptic sensitivity to TNFalpha and the alpha(2)-adrenergic autoreceptor in the pathogenesis of neuropathic pain. Accumulation of TNFalpha is increased initially in a region of the brain containing the locus coeruleus (LC) at day 4 post-ligature placement, followed by an increase in TNFalpha in the hippocampus at day 8 post-ligature placement, coincident with hyperalgesia. Levels of TNFalpha in the thoraco-lumbar spinal cord are also increased at day 8 post-ligature placement. Concurrently, alpha(2)-adrenergic receptor and TNFalpha-induced inhibition of NE release are increased, and stimulated NE release is decreased in superfused hippocampal slices isolated at day 8 post-ligature placement. Stimulated NE release is also decreased in spinal cord slices (lumbar region) from animals undergoing CCI, although in contrast to that which occurs in the hippocampus, alpha(2)-adrenergic receptor inhibition of NE release is not changed. These results indicate an important role that TNFalpha plays in adrenergic neuroplastic changes in a region of the brain that, among its many functions, appears to be a crucial link in the conscious perception of pain. We predict that neuroplastic changes, involving increased functional responses of alpha(2)-adrenergic autoreceptors and increased presynaptic sensitivity to TNFalpha, culminate in decreased NE release in the CNS. These neuroplastic changes provide a mechanism for the role of CNS-derived TNFalpha in the pathogenesis of persistent pain.
The introduction of intravenous regional guanethidine (IVRG) block in 1974 (1,2) has transformed the management of reflex sympathetic dystrophy (RSD). This successful technique has notably withstood the test of time, and remains one of the most effective ways of treating limbs (especially the hands) disabled by RSD. Moreover, the guanethidine technique has generated many new ideas about the etiology of this enigmatic condition (3). The main limitation of the guanethidine technique on a world-wide basis is the unavailability of parenteral guanethidine in some countries. Reserpine and bretylium have a similar action to guanethidine, and can be used as substitutes in the IVR technique but their effects are less clinically useful. Alpha-adrenoeeptor blockers such as thymoxamine can be used in the IVR technique to produce antisympathetic block but again the results are poor compared with guanethidine.
Using the rat paw pressure test, in which sensitivity is increased by intraplantar injection of prostaglandin E2 (PGE2), we conducted a study using several K+ channel blockers. The objective was to determine what types of K+ channels could be involved in the peripheral antinociceptive action of the nitric oxide donor sodium nitroprusside (SNP). SNP elicited a dose-dependent (250 and 500 μg/paw) peripheral antinociceptive effect, which was considered local, since only higher doses produced an effect in the contralateral paw. The effect of SNP (500 μg/paw) was dose-dependently antagonized by intraplantar administration of the sulfonylureas tolbutamide (20, 40 and 160 μg) and glibenclamide (40, 80 and 160 μg), selective blockers of ATP-sensitive K+ channels. Charybdotoxin (2 μg/paw), a selective blocker of high conductance Ca2+-activated K+ channels, and apamin (10 μg/paw), a selective blocker of low conductance Ca2+-activated K+ channels, did not modify the peripheral antinociception induced by SNP. Tetraethylammonium (2 mg/paw), 4-aminopyridine (200 μg/paw) and cesium (800 μg/paw) also had no effect. Based on this experimental evidence, we conclude that the activation of ATP-sensitive K+ channels could be the mechanism by which nitric oxide, donated by SNP, induces peripheral antinociception, and that Ca2+-activated K+ channels and voltage-dependent K+ channels appear not to be involved in the process.
Hypoxia precedes neovascularization in many retinal diseases that can lead to irreversible vision loss. The transcription factor NF-kappaB is activated by hypoxia and regulates the expression of many genes, including angiogenic factors. The relation between the NF-kappaB activation and the cytokine-induced neutrophil chemoattractant (CINC), a member of the interleukin-8 (IL-8) family, was investigated by immunohistochemistry in a rat model of proliferative retinopathy presumably caused by relative hypoxia. Activated NF-kappaB and CINC immunoreactivity was detected in retinal glial cells in the nonperfused retina and in neovascular cells. Activated NF-kappaB was detected before the CINC staining, and both of these events occurred before the development of neovascularization. The intensity of both activated NF-kappaB and CINC staining remained increased during the development of neovascularization and then declined as neovascularization regressed. In rat retinal glial cells in vitro, dexamethasone, an inhibitor of NF-kappaB activation, prevented the hypoxia-induced increase in the amount of CINC mRNA. Furthermore, CINC induced neovascularization in a rat corneal pocket model. These results suggest that hypoxia-induced activation of NF-kappaB results in CINC production and participates in the induction of retinal neovascularization.
The role of cAMP and protein kinase A (PKA) in nociceptor sensitisation has been studied in frog skin in vitro. Multifibre nerve responses during noxious heating were enhanced by adding forskolin, an agent that elevates cAMP. H-89, a PKA antagonist, blocked the increased responses due to forskolin, but did not affect baseline responses. Thus, cAMP appears to act via PKA when sensitising nociceptors in frog skin.
Prostaglandins stimulate cAMP increase in several biological systems including CNS. The possible participation of a cAMP/Ca2+ related mechanism in prostaglandin induced hyperalgesia in the rat paw, as measured by a modification of the Randall-Selitto method was investigated. A serie of agents was administered in the paw in an attempt to change either Ca2+ or cyclic AMP concentration at the nociceptive terminations. PGE2, dibutyryl cyclic AMP, isoprenaline, noradrenaline, adrenaline, Ca2+ionophore (A23187), BaCl2 caused a dose dependent hyperalgesia. The hyperalgesic effect of these substances was enhanced by methyl-xanthines. Cyclic GMP as well as agents which interfere with Ca2+ influx (verapamil and lanthanum) were local analgesics in normal and hyperalgesic paws.
The peripheral and central effects of some non-steroid anti-inflammatory drugs, aspirin, indomethacin, paracetamol and phenacetin were studied by comparing their intraplantar and intracerebroventricular effects on hyperalgesia induced by carrageenin injected into the rat paw. Hyperalgesia was measured by a modification of the Randall-Selitto test. The agents tested had antialgesic effects when given by any route. Their intraventricular administration enhanced the antialgesic effect of anti-inflammatory drugs administered into the paw. Previous treatment of one paw with carrageenin reduced the oedema caused by a second injection of carrageenin in the contralateral paw. In contrast, it had no effect on the intensity of hyperalgesia but shortened the time necessary for it to reach a plateau. Administration of a prostaglandin antagonist (SC-19220) in the cerebral ventricles, in the rat paw or in both sites, significantly inhibited the hyperalgesia evoked by carrageenin. The maximal hyperalgesic effect of intraplantar injections of prostaglandin E2 could be further enhanced by its cerebroventricular administration. It was suggested that carrageenin hyperalgesia has a peripheral and a central component and that the cyclo-oxygenase inhibitors used may exert an antialgesic effect by preventing the hyperalgesia induced by a peripheral and/or central release of prostaglandins.
Hyperalgesia induced in rat paws or dog knee joints by prostacyclin (PGI2) and prostaglandin E2 was measured by a modification of the Randall-Selitto method (1) or by the degree of incapacitation (2). In both species PGI2 induced an immediate hyperalgesic effect but the effect of PGE2 had a longer latency. Low doses of PGI2 caused a short lasting effect but PGE2, large doses of PGI2 or successive administration of small doses of PGI2 caused a long lasting effect. It is suggested that prostacyclin mediates rat paw hyperalgesia induced by carrageenin. The long lasting hyperalgesic effect of PGE2 and high doses of PGI2 is possibly an indirect effect caused by stimulation of a sensory nerve sensitising mechanism.
In various chronic painful states, the sympathetic nerve supply was blocked either by injecting the sympathetic chain and ganglia with local anaesthesia or by the injection of guanethidine during occlusion of the circulation. There was a striking relation between the presence of hyperpathia and the relief of pain by the blocks. The sympathetic block was unlikely to relieve the pain unless hyperpathia accompanied the pain; when hyperpathia was present, a sympathetic block relieved both the constant pain and the hyperpathia. The effectiveness of the guanethidine blocks shows that the pain and the hyperpathia are maintained by the emission of noradrenaline in the periphery. The facts related to the sympathetic system and sensibility are discussed.
The hyperalgesic activities in rats of interleukin‐1β (IL‐1β), IL‐6, IL‐8, tumour necrosis factor α (TNFα) and carrageenin were investigated.
IL‐6 activated the previously delineated IL‐1/prostaglandin hyperalgesic pathway but not the IL‐8/sympathetic mediated hyperalgesic pathway.
TNFα and carrageenin activated both pathways.
Antiserum neutralizing endogenous TNFα abolished the response to carrageenin whereas antisera neutralizing endogenous IL‐1β, IL‐6 and IL‐8 each partially inhibited the response.
The combination of antisera neutralizing endogenous IL‐1β + IL‐8 or IL‐6 + IL‐8 abolished the response to carrageenin.
These results show that TNFα has an early and crucial role in the development of inflammatory hyperaglesia.
The delineation of the roles of TNFα, IL‐1β, IL‐6 and IL‐8 in the development of inflammatory hyperalgesia taken together with the finding that the production of these cytokines is inhibited by steroidal anti‐inflammatory drugs provides a mechanism of action for these drugs in the treatment of inflammatory hyperalgesia.
Recent evidence has suggested that cAMP plays a role as a second messenger in the decrease in nociceptive threshold (or hyperalgesia) produced by agents acting on primary afferent terminals. In support of this hypothesis we report that intradermal injection of a direct activator of adenyl cyclase, forskolin, produces a dose-dependent hyperalgesia in the rat. The duration of this hyperalgesia was prolonged by the phosphodiesterase inhibitors, isobutylmethylxanthine and rolipram. Forskolin hyperalgesia was antagonized by the Rp isomer of cyclic adenosine-3'5'-monophosphothioate, an analog of cAMP that prevents the phosphorylation of the cAMP protein kinase. The Rp isomer of cyclic adenosine-3'5'-monophosphothioate also inhibited the hyperalgesia induced by a membrane-permeable analogue of cAMP, 8-bromocyclic adenosine monophosphate, as well as the hyperalgesia induced by agents that are presumed to act directly on primary afferent nociceptors: prostaglandin E2, prostaglandin I2, (8R,15S)-dihydroxyicosa(5E-9,11,13Z)tetraenoic acid; and the adenosine A2-agonist 2-phenylaminoadenosine. Although the cAMP second messenger system contributes to primary afferent hyperalgesia, we found no evidence for a contribution of protein kinase C. Thus, hyperalgesia induced by prostaglandin E2, prostacyclin (prostaglandin I2), (8R,15S)-dihydroxyicosa(5E-9,11,13Z)tetraenoic acid, the adenosine A2-agonist 2-phenylaminoadenosine, 8-bromocyclic adenosine monophosphate and the direct activator of adenyl cyclase, forskolin, were not significantly attenuated by the selective inhibition of protein kinase C by the 19-31 fragment of protein kinase C. Two other inhibitors of protein kinase C, sphingosine and staurosporine, also failed to attenuate prostaglandin E2-induced hyperalgesia.
The hyperalgesic effects of interleukin‐8 (IL‐8), interleukin‐1β (IL‐1β) and carrageenin were measured in a rat paw pressure test.
IL‐8 evoked a dose‐dependent hyperalgesia which was attenuated by a specific antiserum, the β‐adrenoceptor antagonists atenolol and propranolol, the dopamine 1 receptor antagonist SCH 23390 and the adrenergic neurone‐blocking agent guanethidine. The hyperalgesia was not attenuated by the cyclo‐oxygenase inhibitor indomethacin or the IL‐1β analogue Lys‐ d ‐Pro‐Thr.
IL‐1β‐evoked hyperalgesia was attenuated by indomethacin and Lys‐ d ‐Pro‐Thr but not by atenolol or SCH 23390.
Carrageenin‐evoked hyperalgesia was attenuated by atenolol, indomethacin and anti‐IL‐8 serum. The effects of atenolol and anti‐IL‐8 serum were not additive. The effects of indomethacin and anti‐IL‐8 serum were additive: this combination abolished carrageenin‐evoked hyperalgesia.
A new biological activity of IL‐8 is described, namely the capacity to evoke hyperalgesia by a prostaglandin‐independent mechanism. IL‐8 is the first endogenous mediator to be identified as evoking hyperalgesia involving the sympathetic nervous system. Since IL‐8 is released by activated macrophages and endothelial cells it may be a humoral link between tissue injury and sympathetic hyperalgesia.
A new model of chronic hypersensitivity was developed in the rat by daily intraplantar administration of either prostaglandin E2 dopamine or isoprenaline, for a period of 2 weeks. Like other hyperalgesic mediators, dibutyryl-cAMP, when applied to the paws, caused an acute effect but did not produce persistent hypersensitivity. The persistent hypersensitive state was not affected by a typical non-steroidal anti-inflammatory drug (indomethacin), was temporarily inhibited by a centrally acting analgesic (morphine), was partially inhibited by a protein synthesis inhibitor (cycloheximide) and abolished by a single dose of peripherally acting analgesics such as dipyrone or N-methyl morphine. Once the residual hypersensitivity had been abolished with dipyrone or N-methyl morphine, a small dose of prostaglandin E2, dopamine or Interleukin-1 beta, which in normal animals causes a mild and short lived effect, restored the persistent hypersensitive state. This ability to restore the persistent effect was not observed with intraplantar administration of dibutyryl-cAMP. Our results suggest the existence of a peripheral trace of inflammatory pain, a phenomenon which may be associated with stimulation of neuronal adenylate cyclase and protein synthesis. This concept may explain part of the puzzle of chronic inflammatory pain and lead to the development of new analgesics.
Cyclooxygenase (prostaglandin E2 and prostaglandin I2) and lipoxygenase [8(R), 15(S)-dihydroxyicosa-(5E-9,11,13Z)-tetraenoic acid] products of arachidonic acid metabolism are thought to produce peripheral hyperalgesia by a direct action on the primary afferent nociceptor. In this study we investigated the possibility that these eicosanoids generate hyperalgesia through a common second messenger in the rat. We report that 8-bromo cAMP, a membrane permeable analogue of cAMP, produces a dose-dependent hyperalgesia that is not affected by treatments that interrupt indirect routes of hyperalgesia production including sympathectomy with 6-hydroxydopamine, depletion of polymorphonuclear leukocytes (a source of hyperalgesic eicosanoids) with hydroxyurea, or blockade of the cyclooxygenase pathway of arachidonic acid metabolism with indomethacin. The phosphodiesterase inhibitor isobutyl-methylxanthine markedly prolongs the hyperalgesic effect of 8-bromo cAMP as well as those of the directly acting hyperalgesic agents prostaglandin E2, prostaglandin I2 and 8(R),15(S)-dihydroxyicosa-(5E-9,11,13Z)-tetraenoic acid. We conclude that the effect of all known hyperalgesic eicosanoids is mediated by the cAMP second messenger system and suggest, therefore, that cAMP mediates peripheral hyperalgesia in primary afferent nociceptors.
Non-steroidal anti-inflammatory drugs (NSAID) only partially inhibit the hyperalgesia in the inflammation induced by carrageenin in the hind rat paw, one of the most frequently used nociceptive tests. We now report that either the guanethidine depletion of peripheral sympathomimetic amines or the treatment with adrenoceptor antagonists (beta-blockers) and a specific dopamine (DA)-1 antagonist (SCH 23390) significantly reduced carrageenin hyperalgesia. These antagonists also abolished the rat paw hyperalgesia induced by several sympathomimetic amines as well as that induced by a selective DA-1 agonist, SKF 38393. Blockade of uptake-1 by cocaine potentiated the hyperalgesia induced by carrageenin and sympathomimetic amines. We conclude that there is a sympathetic component, possibly mediated by a DA-1 type receptor in carrageenin-induced hyperalgesia. This component may predominate in certain types of pain not sensitive to NSAID. If so, selective peripheral DA-1 antagonists could be developed as a novel class of analgesics.
Interleukin-1 (IL-1) describes two inflammatory proteins, IL-1 alpha and IL-1 beta, produced by activated macrophages and other cell types and encoded by two genes. Their amino acid sequences have only 26% similarity, but their biological activities are comparable, with a few exceptions; indeed, both molecules appear to act at the same receptor. As IL-1 release prostaglandins which sensitize nociceptors in man and in experimental animals, we tested IL-1 alpha and IL-1 beta in rats for hyperalgesic (nociceptive) activity. Our results show that IL-1 beta given systemically is an extremely potent hyperalgesic agent with a probable peripheral site of action; IL-1 alpha is approximately 3,000 times less active than IL-1 beta. We have delineated the region of IL-1 beta mediating the hyperalgesic effect and developed an analgesic tripeptide analogue of IL-1 beta which antagonizes hyperalgesia evoked by IL-1 beta and by the inflammatory agent carrageenan.
We investigated the participation of a sympathetic component in the abdominal contortions induced by intraperitoneal injection of 0.6% acetic acid in the mouse. The beta blocker propranolol (4 mg/kg, sc) caused a small significant (19%) blockade of the contortions but strongly potentiated (greater than 80%) the effect of indomethacin (30% at 5 mg/kg, sc). Significant inhibition of writhing was also observed with sympatholytics such as guanethidine (27% at 30 mg/kg, sc) and by a specific dopamine-I antagonist, SCH 23390 (62% at 400 micrograms/kg, sc). Tyramine, which releases sympathomimetic amines, and cocaine, which partially blocks the uptake of amines, potentiated acetic acid writhing. Intraperitoneal administration of noradrenaline (187 micrograms/kg)potentiated acetic acid-induced writhing. These results are consistent with the suggestion of Nakamura and Ferreira (1) that inflammatory nociception has a dual component: one mediated by cyclooxygenase metabolites and another by sympathetic amines, possibly acting through a DA-1 type receptor.
Interleukin-1 (IL-1) has been shown to induce inflammatory reactions in part through increased prostaglandin production. Prostaglandins of the E- and I-type sensitize nociceptors in peripheral tissues.
We have therefore investigated the effect of IL-1 perfusion in the isolated rabbit ear, a model which allows the assessment of peripheral pain. Natural IL-1 from human monocytes, IL-1 from glioblastoma cells as well as recombinant IL-1 α or β, increased the pain reflex induced by acetylcholine in a concentration dependent manner. The PGE2 levels were measured in the perfusate and were found to be enhanced more than 10-fold after the infusion of IL-1α or IL-1β. This effect was paralleled by the enhanced pain reflexes and persisted for at least one hour after cessation of the IL-1 perfusion. Both the increased pain reflexes as well as the enhanced PGE2 levels were abolished by addition of the cyclooxygenase inhibitor diclofenac-Na (Voltaren®) to the perfusion fluid. These results show that besides the numerous known physiological functions of IL-1, it may also play a role in peripheral pain sensations.
1. The effects of N-methyl morphine and N-methyl nalorphine were studied on the hyperalgesia induced by prostaglandin E2 in the rat paw. Morphine and N-methyl morphine injected intraperitoneally (2-8 mg/kg) caused a dose-dependent analgesia. The potency of N-methyl morphine was of the same order of magnitude as its parent compound in causing analgesia. 2. Nalorphine caused a short-lasting analgesia followed by an enhancement of prostaglandin-induced hyperalgesia. In contrast, its analogue, N-methyl nalorphine, injected intraperitoneally, induced analgesia but did not enhance the hyperalgesia induced by prostaglandin E2 or induce hyperalgesia in the control paw. 3. Treatment of the animals with N-methyl nalorphine at a dose which had no apparent analgesic effect antagonized the analgesic effect of morphine or N-methyl morphine. 4. Administration of a low dose of N-methyl nalorphine into the paw totally antagonized the analgesic effect of N-methyl morphine administered either locally into the paw, or intraperitoneally. 5. It is concluded that quaternary analogues of morphine and nalorphine, which do not have central effects because they do not cross the blood-brain barrier, retain the peripheral analgesic effects of the parent compounds.
Guanethidine was infused by the regional intravenous technique into upper and lower limbs of patients with painful hyperpathic states, due to peripheral or central lesions. The relief of pain and hyperpathia occurred within 20 minutes of infusion and lasted between three and 128 hours; in a few patients, the relief has lasted for months. Great reduction in skin conductance and vasodilatation occurred, there being marked variation in the time of onset and duration of these effects. In some cases there was marked pilo-erection. Guanethidine given in this way did not completely block the sympathetic control of digital blood-vessels. There were no effects on sensibility of normally innervated regions.
Indomethacin, a typical cyclo-oxygenase inhibitor, acts as an analgesic by preventing the hyperalgesia induced by prostaglandins during inflammation. Analgesics of the dipyrone type directly block the sensitization of nociceptors. In the present investigation, the analgesic effect of diclofenac was compared with that of indomethacin in two algesimetric tests which permit discrimination between the two types of analgesic: the rat knee joint incapacitation and the rat paw hyperalgesia tests. The analgesics were given either pre- or posttreatment relative to the induction of hyperalgesia with carrageenin or prostaglandin E2. In both tests intraperitoneal pretreatment with indomethacin was equally or slightly more potent than diclofenac. Posttreatment with diclofenac was more effective than posttreatment with indomethacin. This was particularly evident in the paw hyperalgesia test in which posttreatment with indomethacin was not effective while diclofenac caused dose-dependent analgesia. When nociception was induced by PGE2 in both tests, the administration of indomethacin directly into the knee joint or rat paw had no effect while diclofenac continued to cause dose-dependent analgesia. Thus, diclofenac has a direct effect on ongoing hyperalgesia in addition to its ability to block cyclo-oxygenase. Naloxone and N-methyl-nalorphine did not affect diclofenac analgesia, thus indicating that the analgesic effect of the latter is independent of a central or peripheral opioid effect. Local administration of agents which inhibit the formation of nitric oxide (NG-monomethyl-L-arginine) or inhibit the activation of guanylate cyclase by nitric oxide (methylene blue) abolished diclofenac-induced analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)
The subcutaneous injection of bacterial endotoxin in Lewis rats produces an acute intraocular inflammation evolving over a 24 hour period. This endotoxin induced uveitis (EIU) is characterised by a biphasic protein exudation and a cellular infiltrate composed of macrophages and polymorphonuclear neutrophils (PMNs). This model was used to study the mechanism of cellular infiltration in ocular inflammation.
EIU was induced by a subcutaneous injection of lipopolysaccharide (LPS) (S typhimurium) at 350 micrograms/kg. The levels of cytokine induced neutrophil chemoattractant (CINC) were measured every 2 hours in the serum and in the aqueous humour by ELISA. The intraocular inflammation was quantified by protein measurement and leucocyte counting.
The kinetics of CINC production in the systemic circulation showed a rapid rise, peaking 2 hours after LPS injection, followed by a progressive decline over the next 8 hours. In the eye, the CINC levels increased above the serum levels 10 hours after EIU induction corresponding to the time of cellular infiltration. When leucocyte entry in the eye was inhibited by 56% and 64% with an antiadhesion molecule antibody, there was only a slight reduction in the aqueous humour CINC levels of 9% and 16%, respectively, indicating that CINC was produced by ocular tissue cells. The specific effect of CINC in the eye was confirmed when a direct intraocular injection of 250 ng of purified CINC was followed by significant PMN infiltration, in the absence of protein exudation.
The data indicate that the production of the CINC chemotactic factor by ocular tissue participates in the inflammatory reaction in EIU.
In normal animals, peripheral nerve injury produces a persistent, neuropathic pain state in which pain is exaggerated and can be produced by nonpainful stimuli. Here, mice that lack protein kinase C gamma (PKCgamma) displayed normal responses to acute pain stimuli, but they almost completely failed to develop a neuropathic pain syndrome after partial sciatic nerve section, and the neurochemical changes that occurred in the spinal cord after nerve injury were blunted. Also, PKCgamma was shown to be restricted to a small subset of dorsal horn neurons, thus identifying a potential biochemical target for the prevention and therapy of persistent pain.
The inflammatory response is mediated by a family of chemotactic cytokines, designated chemokines. The receptor usage of the CXC chemokine granulocyte chemotactic protein-2 (GCP-2) was compared with that of interleukin-8 (IL-8) and epithelial-cell-derived neutrophil attractant-78 (ENA-78). Chemokine activities were evaluated by measurement of intracellular calcium increase and by chemotaxis and binding assays, using CXC chemokine receptor (CXCR)-transfected cell lines. GCP-2 was equally potent at inducing a rise in [Ca2+]i in both CXCR1-transfected and CXCR2-transfected cells (minimal effective concentration 3 nM). IL-8 augmented the [Ca2+]i more efficiently in CXCR1-transfectants than in CXCR2-transfectants, whereas for ENA-78, threefold higher concentrations were necessary to obtain a calcium response in CXCR1-transfected cells than in CXCR2-transfectants. GCP-2 desensitized the calcium increase induced by IL-8 in both CXCR1-transfected and CXCR2-transfected cells, but ENA-78 only affected the IL-8-induced calcium response in CXCR2-transfectants. The half-maximal effective concentrations for migration of CXCR2-transfectants in response to GCP-2 and ENA-78 were similar (0.1 nM), whereas GCP-2 was tenfold more potent than ENA-78 on CXCR1-transfectants. Half-maximal migration of CXCR1-transfected and CXCR2-transfected cells was obtained with IL-8 at concentrations of no more than 0.01 nM. Radiolabeled IL-8 could efficiently be displaced from CXCR2 by IL-8, GCP-2 and ENA-78. In contrast, only IL-8 and GCP-2 but not ENA-78, competed for 125I-IL-8 binding to CXCR1. From these data, it can be concluded that, in addition to IL-8, GCP-2, but not ENA-78, efficiently binds to both CXCR1 and CXCR2. The differential receptor usage of the structurally related ELR+ CXC chemokines GCP-2 and ENA-78 is indicative of a different role in inflammatory reactions.
The objective of the present paper was to evaluate the relevance of neuronal balance of cyclic AMP and cyclic GMP concentration for functional regulation of nociceptor sensitivity during inflammation.
Injection of PGE2 (10–100 ng paw−1) evoked a dose-dependent hyperalgesic effect which was mediated via a cyclic AMP-activated protein kinase (PKA) inasmuch as hyperalgesia was blocked by the PKA inhibitor H89.
The PDE4 inhibitor rolipram and RP73401, but not PDE3 and PDE5 inhibitors potentiated the hyperalgesic effects of PGE2. The hyperalgesic effect of dopamine was also enhanced by rolipram. Moreover, rolipram significantly potentiated hyperalgesia induced by carrageenan, bradykinin, TNFα, IL-1β, IL-6 and IL-8. This suggests that neuronal cyclic AMP mediates the prostanoid and sympathetic components of mechanical hyperalgesia. Moreover, in the neuron cyclic AMP is mainly metabolized by PDE4.
To examine the role of the NO/cyclic GMP pathway in modulating mechanical hyperalgesia, we tested the effects of the soluble guanylate cyclase inhibitor, ODQ. This substance counteracts the inhibitory effects of the NO donor, SNAP, on the hyperalgesia induced by PGE2.
The ODQ potentiated hyperalgesia induced by carrageenan, bradykinin, TNFα, IL-1β, IL-6 and IL-8. In contrast, ODQ had no significant effect on the hyperalgesia induced by PGE2 and dopamine. This indicates that the hyperalgesic cytokines may activate soluble guanylate cyclase, which down-regulate the ability of these substances to cause hyperalgesia. This event appears not to be mediated by prostaglandin or dopamine.
In conclusion, the results presented in this paper confirm an association between (i) hyperalgesia and elevated levels of cyclic AMP as well as (ii) antinociception and elevated levels of cyclic GMP. The intracellular levels of cyclic AMP that enhance hyperalgesia are controlled by the PDE4 isoform and appear to result in activation of protein kinase A whereas the intracellular levels of cyclic GMP results from activation of a soluble guanylate cyclase.
British Journal of Pharmacology (1999) 127, 671–678; doi:10.1038/sj.bjp.0702601
Tumour necrosis factor-alpha is a pro-inflammatory cytokine involved in many aspects of acute phase and immune responses. Species specificity in the biological action and receptor binding of TNF-alpha make it desirable to use homologous reagents in experimental models, both in vivo and in vitro. As the rat is the model of choice in many investigations on fever, trauma and pathology, there is a need for specific rat reagents. In this paper, we describe the production of recombinant rat TNF-alpha in milligram quantities, using a methylotrophic yeast expression system, Pichia pastoris. Recombinant TNF-alpha was produced intracellularly in a soluble form, cells were lysed and the protein purified by ammonium sulphate precipitation, Sephadex G75 fractionation and finally, ion-exchange chromatography. The purified recombinant rat TNF-alpha had a molecular mass of 17401.38 +/- 0.38 Da, which is within 1 Da of the value predicted by the sequence data, taking into account N-acetylation of the initial methionine residue and a single disulphide bridge between amino acids 70 and 101. Recombinant rat TNF-alpha was shown to be 20 x fold more biologically active in the WEHI cytotoxicity assay, than the human standard preparation. Polyclonal antibodies were raised against purified recombinant rat TNF-alpha, these reagents were used to develop a novel enzyme-linked immunosorbant assay (ELISA). The ELISA was sensitive to 10 pg.ml- 1 rat TNF-alpha and was specific for TNF-alpha, showing no cross-reactivity with rat IL-1alpha, rat IL-1beta, rat IL-1Ra or rat IL-6. The ELISA was used to measure TNF-alpha in the plasma of rats injected with bacterial endotoxin and in cultures of rat white blood cells. The ELISA was shown to be a robust method suitable for use in assaying samples generated in both in vivo or in vitro experiments.
Nerve signals arising from sites of tissue or nerve injury lead to long-term changes in the central nervous system and contribute to hyperalgesia and the amplification and persistence of pain. These nociceptor activity-induced changes are referred to as central sensitization. Central sensitization involves an increase in the excitability of medullary and spinal dorsal horn neurons brought about by a cascade of events, including neuronal depolarization, removal of the voltage-dependent magnesium block of the N-methyl-D-aspartate (NMDA) receptor, calcium entry into neurons, phosphorylation of the NMDA receptor, a change in the cell's excitability, and an increase in synaptic strength. These changes also include activation of other ionotropic and metabotropic excitatory amino acid receptors, neuropeptides such as substance P, neurotrophins, and kinases involved in the phosphorylation process. Central sensitization occurs in trigeminal nociceptive pathways, and more robust neuronal hyperexcitability occurs following deep tissue stimulation than following cutaneous stimulation. By means of Fos protein immunocytochemistry, researchers have found that 2 distinct regions are activated: the subnucleus interpolaris/caudalis transition zone (Vi/Vc) and the caudal subnucleus caudalis. The latter exhibits changes very similar to those in the spinal dorsal horn, but the Vi/Vc zone likely is involved in autonomic nervous system processing and activation of the pituitary-adrenal axis. Descending systems are also an important component of the central sensitization process and provide the neural networks by which cognitive, attentional, and motivational aspects of the pain experience modulate pain transmission. These findings of nociceptor activity-induced neuronal plasticity have important clinical implications in the development of new approaches to the management of persistent pain.
Rat cytokine-induced neutrophil chemoattractant-1 (CINC-1), CINC-2 and CINC-3/macrophage inflammatory protein-2 (MIP-2), members of the CXC chemokine family, are potent chemotactic factors for neutrophils. In order to identify the receptor for CINCs, rat CXC chemokine receptor 2 (CXCR2) was cloned and expressed in HEK293 cells. CINC-1, CINC-2 and CINC-3 induced calcium mobilizations dose-dependently in CXCR2-transfected cells, whereas formyl-methionyl-leucyl-phenylalanine (FMLP) did not. CINC-3 induced enhancement of cytoplasmic calcium concentration more potently than CINC-1 and CINC-2, and desensitized calcium transients induced by CINC-1 and CINC-2, which were essentially identical to those observed in rat neutrophils. In addition, anti-CXCR2 serum inhibited neutrophil chemotactic activities of three types of CINCs almost completely. The mutant CINC-3, whose amino-terminal amino acid sequence (SELR) was replaced to AAR, lost chemotactic activity of its own but inhibited that of CINC-1 and CINC-2 potently, and that of CINC-3 weakly. The results indicate that rat CXCR2 on neutrophils is the unique receptor for all three types of CINCs, and CINC-1/-2 and CINC-3 exert different biological activities through the common receptor.
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