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Glucocorticoid inhibition of adjuvant arthritis synovial macrophage nitric oxide production: Role of lipocortin I
Abstract
Nitric oxide (NO) is a mediator of inflammatory injury which is inhibited by glucocorticoids and is implicated in rheumatoid (RA) and adjuvant arthritis (AA). The glucocorticoid-induced anti-inflammatory molecule lipocortin 1 is expressed in RA synovium, but the effects of lipocortin 1 on synovial inflammation have been little studied. We investigated the effects of glucocorticoids and lipocortin 1 on inducible NO synthase (iNOS) and glucocorticoids on the induction of lipocortin 1 in AA synovial macrophages. NO production was measured by Griess assay in supernatants of day 14 AA rat synovial explants and of synovial macrophages purified from enzyme-digested synovium and treated with lipopolysaccharide (LPS) 1 microg/ml, dexamethasone (DEX) 10(-7) M, and anti-lipocortin 1 MoAb. iNOS and lipocortin 1 expression were detected by flow cytometry using specific MoAb. Cell surface lipocortin was determined by Western blot. NO was produced by all AA synovial explants and NO was released by cultured synovial macrophages (14.5 +/- 2.1 micromol/24 h). iNOS was detected in synovial macrophages (ED-1+) by permeabilization flow cytometry. LPS increased synovial macrophage NO release (P < 0.0001) and iNOS expression (P = 0.04). DEX inhibited constitutive (P = 0.002) and LPS-induced (P < 0.001) NO release and iNOS expression (P = 0.03). DEX inhibition of synovial macrophage NO was associated with induction of cell surface and intracellular lipocortin 1. Anti-lipocortin 1 MoAb treatment reduced the inhibition of NO release by DEX (P = 0.002), but had no effect on iNOS expression. These findings demonstrate a role for lipocortin I in the inhibition by glucocorticoids of AA synovial macrophage iNOS activity.
... Effect of dexamethasone on transepithelial ion transport. It has been shown in several systems that glucocorticoid treatment downregulates iNOS expression and NO production (4,32,33). It was our goal to determine whether dexamethasone would mimic the effects of the iNOS-selective inhibitor SMT in modulating both chlo-ride and sodium transport. ...
... Effect of dexamethasone on iNOS expression and NO production. It has been previously reported that dexamethasone prevents the expression of iNOS (4,32,33). ...
... Similar results are obtained when C57BL/6J mice are treated with the glucocorticoid dexamethasone. Dexamethasone has been shown to downregulate the production of iNOS (4,32,33). We have substantiated this property of dexamethasone in our system by showing reduced staining of immunoreactive iNOS in lung sections from dexamethasone-treated mice. ...
Transepithelial ion transport is regulated by a variety of cellular factors. In light of recent evidence that nitric oxide (NO) production is decreased in cystic fibrosis airways, we examined the role of NO in regulating sodium and chloride transport in murine nasal epithelium. Acute intervention with the inducible NO synthase (iNOS)-selective inhibitor S-methylisothiourea resulted in an increase of amiloride-sensitive sodium absorption observed as a hyperpolarization of nasal transepithelial potential difference. Inhibition of iNOS expression with dexamethasone also hyperpolarized transepithelial potential difference, but only a portion of this increase proved to be amiloride sensitive. Chloride secretion was significantly inhibited in C57BL/6J mice by the addition of both S-methylisothiourea and dexamethasone. Mice lacking iNOS expression [NOS2(-/-)] also had a decreased chloride-secretory response compared with control mice. These data suggest that constitutive NO production likely plays some role in the downregulation of sodium absorption and leads to an increase in transepithelial chloride secretion.
... Synovial tissue explant culture. Synovial tissue was cultured as described (13). Briefly, synovium was excised from the joints of the hind feet on day 14 of AIA and cultured in RPMI/2% heat-inactivated fetal calf serum (ICN Biomedicals, Sydney, Australia). ...
... Results were obtained by an absorbance plate reader at 450 nm, and the detection limit of the assay was 0.1 ng/ml. Nitric oxide (NO) production in synovial explants was assessed by measuring the nitrite concentration in culture supernatants by use of the Griess reaction, as described elsewhere (13). Briefly, the Griess reagent (1:1 mixture of 1.5% sulfanilamide [p-aminobenzenesulfonamide]; Sigma) in 1M hydrochloric acid and 0.15% naphthylethylenediamine (Sigma) and the supernatant were mixed in a 96-well plate, and the absorbance was read at 530 nm. ...
... For example, antiinflammatory activity of annexin I mimicking that of exogenous glucocorticoids has been demonstrated in several simple animal models of acute inflammation (17)(18)(19)(20)(21). In vitro, annexin I has been shown to inhibit cell differentiation and proliferation (22,23), eicosanoid release (24,25), reactive oxygen species production (26), and NO production (13,27). The hypothesis that annexin I also mediates certain actions of endogenous glucocorticoids in inflammation is supported by studies in adrenalectomized animals, which show that endogenous glucocorticoids both inhibit inflammatory disease (28)(29)(30) and regulate annexin I synthesis (31)(32)(33). ...
Annexin I is an endogenous antiinflammatory mediator, expressed in rheumatoid arthritis (RA) synovium, the contribution of which to autoregulation of the synovial inflammatory response has not been examined in models of RA. We investigated the antiinflammatory role of annexin I in rat adjuvant arthritis.
Rats with adjuvant-induced arthritis (AIA) were treated with a specific anti-annexin I monoclonal antibody (mAb), isotype control IgG, and/or dexamethasone. Clinical outcomes and synovial synthesis of tumor necrosis factor alpha (TNFalpha), prostaglandin E2 (PGE2), and nitric oxide were examined, and annexin I expression was assessed by flow cytometry and reverse transcription-polymerase chain reaction.
Anti-annexin I mAb reversed the effects of dexamethasone on the clinical features of AIA and exacerbated AIA in the absence of exogenous glucocorticoid. Clinical exacerbation of AIA by anti-annexin I mAb was accompanied by significantly increased synovial TNFalpha and PGE2, suggesting that annexin I tonically inhibits the production of these mediators. Anti-annexin I mAb treatment was associated with significantly reduced leukocyte intracellular annexin I, despite increased annexin I messenger RNA expression, consistent with a depletion effect of extracellular mAb via the cell surface.
Annexin I is a key endogenous inhibitory mediator of arthritis via mechanisms that include inhibition of cytokine and effector molecule production. Moreover, a synthesis-independent depletion of intracellular annexin I by extracellular antibody supports the hypothesis that externalization of annexin I is involved in its mode of action.
... Nitric oxide The reaction of nitric oxide (NO) with superoxide generates peroxynitrite (Beckman et al. 1994) which, under the acid conditions often found in regions of inflammation and ischaemia, yields the hydroxyl radical OH X , the most highly reactive and toxic of the ROS (Fig. 1). The study of experimental arthritis in animals has confirmed an increased activity of inducible NO synthetase (iNOS) (McCartney-Francis et al. 1993;Sakurai et al. 1995) with a raised production of NO (Cannon et al. 1996;Grabowski et al. 1996a;Yang et al. 1998). The inhibition of NOS can suppress disease activity in parallel with a fall in plasma nitrotyrosine or nitrite (McCartney-Francis et al. 1993;Kaur & Halliwell, 1994;Connor et al. 1995;Cannon et al. 1996;Santos et al. 1997;Stichtenoth & Frolich, 1998). ...
... Corticosteroids diminish NOS activity and NO production in several animal models of RA including that promoted by the direct application of cytokines to joint tissue (Yang et al. 1998;Grabowski et al. 1996b). Dexamethasone reduced NO produced by synovial explants and cultures of synovial macrophages from rats with adjuvant-induced arthritis (Yang et al. 1998). ...
... Corticosteroids diminish NOS activity and NO production in several animal models of RA including that promoted by the direct application of cytokines to joint tissue (Yang et al. 1998;Grabowski et al. 1996b). Dexamethasone reduced NO produced by synovial explants and cultures of synovial macrophages from rats with adjuvant-induced arthritis (Yang et al. 1998). This inhibition of iNOS was associated with an increase of intracellular lipocortin levels, indicating parallels with other anti-inflammatory actions of these compounds. ...
The generation of reactive oxygen species (free radicals) is an important factor in the development and maintenance of rheumatoid arthritis in humans and animal models. One source of free radicals is nitric oxide produced within the synoviocytes and chondrocytes and giving rise to the highly toxic radical peroxynitrite. Several cytokines, including tumour necrosis factor-alpha (TNFalpha) are involved in the formation of free radicals, partly by increasing the activity of nitric oxide synthase. Indeed, nitric oxide may mediate some of the deleterious effects of cytokines on bone resorption. Aspirin, tetracyclines, steroids and methotrexate can suppress nitric oxide synthase. Dietary antioxidants include ascorbate and the tocopherols and beneficial effects of high doses have been reported especially in osteoarthritis. There is also evidence for beneficial effects of beta-carotene and selenium, the latter being a component of the antioxidant enzyme glutathione peroxidase. The polyunsaturated fatty acids (PUFA) include the n-3 compounds, some of which are precursors of eicosanoid synthesis, and the n-6 group which can increase formation of the pro-inflammatory cytokines TNFalpha and interleukin-6, and of reactive oxygen species. Some prostaglandins, however, suppress cytokine formation, so that n-3 PUFA often oppose the inflammatory effects of some n-6-PUFA. gamma-linolenic acid (GLA) is a precursor of prostaglandin E1, a fact which may account for its reported ability to ameliorate arthritic symptoms. Fish oil supplements, rich in n-3 PUFA such as eicosapentaenoic acid have been claimed as beneficial in rheumatoid arthritis, possibly by suppression of the immune system and its cytokine repertoire. Some other oils of marine origin (e.g. from the green-lipped mussel) and a range of vegetable oils (e.g. olive oil and evening primrose oil) have indirect anti-inflammatory actions, probably mediated via prostaglandin E1. Overall, there is a growing scientific rationale for the use of dietary supplements as adjuncts in the treatment of inflammatory disorders such as rheumatoid arthritis and osteoarthritis.
... ANXA1 has been shown to be expressed by many different tissue specific macrophages including alveolar (Ambrose et al. 1992, De Caterina et al. 1993, peritoneal (Peers et al. 1993), and synovial macrophages (Yang et al. 1998) as well as microglial cells (Minghetti et al. 1999), suggesting a regulatory role for the molecule in macrophage activity in general, that is not confined to any given tissue type. The constitutive expression of ANXA1 mRNA and protein by macrophages has been shown reproducibly by many authors to increase following exposure to GC in vitro and in vivo (Ambrose et al. 1992, De Caterina et al. 1993, Peers et al. 1993, Coméra et al. 1995, Perretti & Flower 1996, Yang et al. 1998, Hall et al. 1999. ...
... ANXA1 has been shown to be expressed by many different tissue specific macrophages including alveolar (Ambrose et al. 1992, De Caterina et al. 1993, peritoneal (Peers et al. 1993), and synovial macrophages (Yang et al. 1998) as well as microglial cells (Minghetti et al. 1999), suggesting a regulatory role for the molecule in macrophage activity in general, that is not confined to any given tissue type. The constitutive expression of ANXA1 mRNA and protein by macrophages has been shown reproducibly by many authors to increase following exposure to GC in vitro and in vivo (Ambrose et al. 1992, De Caterina et al. 1993, Peers et al. 1993, Coméra et al. 1995, Perretti & Flower 1996, Yang et al. 1998, Hall et al. 1999. ...
... There are numerous studies establishing that macrophage-derived inflammatory mediators can be inhibited by GC in an ANXA1-dependent manner by the application of immunoneutralisation strategies, including TNF-α and PGE 2 release from human PBMC (Sudlow et al. 1996) and nitric oxide generation by rat synovial macrophages (Yang et al. 1998). In a single study, human recombinant ANXA1, as well as ANXA1 purified from human peripheral blood mononuclear cells (PBMC) or mouse lung inhibited iono- This scheme summarises the concept behind the study of antiinflammation. ...
The concept of anti-inflammation is currently evolving with the definition of several endogenous inhibitory circuits that are important in the control of the host inflammatory response. Here we focus on one of these pathways, the annexin 1 (ANXA1) system. Originally identified as a 37 kDa glucocorticoid-inducible protein, ANXA1 has emerged over the last decade as an important endogenous modulator of inflammation. We review the pharmacological effects of ANXA1 on cell types involved in inflammation, from blood-borne leukocytes to resident cells. This review reveals that there is scope for more research, since most of the studies have so far focused on the effects of the protein and its peptido-mimetics on neutrophil recruitment and activation. However, many other cells central to inflammation, e.g. endothelial cells or mast cells, also express ANXA1: it is foreseen that a better definition of the role(s) of the endogenous protein in these cells will open the way to further pharmacological studies. We propose that a more systematic analysis of ANXA1 physio-pharmacology in cells involved in the host inflammatory reaction could aid in the design of novel anti-inflammatory therapeutics based on this endogenous mediator.
... Annexin I has been demonstrated in human blood leukocytes and RA tissue [12,13]. It exerts a constitutive inhibitory influence, and mediates the inhibitor effects of glucocorticoids, in rodent models of RA [3,9,10,[14][15][16]. Regulated expression of functionally active cell surface annexin I binding sites has been reported in human RA fibroblastlike synoviocytes (FLS) [17,18]. ...
... Cell surface annexin I was obtained by washing cell monolayers with PBS containing 10 mM EDTA, as described in [14]. Briefly, cell monolayers at 2 × 10 5 /mL were washed with PBS and then with PBS containing 10 mM EDTA for 3-5 minutes at room temperature. ...
... These data suggest that DEX induces the translocation of intracellular annexin I to the cell surface, followed by increased expression of annexin I mRNA. A smaller 33 kD fragment, previously shown to be a glucocorticoid-inducible fragment of annexin I [14], was also shown to be increased by DEX. ...
The glucocorticoid (GC)-induced antiinflammatory molecule annexin I is expressed in leukocytes and has antiinflammatory effects in animal models of arthritis, but the expression of annexin I in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) is unknown. We report the constitutive and dexamethasone (DEX)-inducible expression of annexin I in RA FLS. DEX increased FLS annexin I protein translocation and mRNA expression. Interleukin (IL)-1beta also induced annexin I translocation and mRNA but also increased intracellular protein. DEX and IL-1 had additive effects on annexin I mRNA, but DEX inhibited the inducing effect of IL-1beta on cell surface annexin I. These results indicate that glucocorticoids and IL-1beta upregulate the synthesis and translocation of annexin I in RA FLS, but interdependent signalling pathways are involved.
... ANXA1 acted in this situation by moving to the cell surface upon treatment of dexamethasone. One of the actions of ANXA1 is that it blocked the NO after it was inducted by glucocorticoids (Yang et al. 1998). Dexamethasone was able also to inhibit hyperalgesic effect produced by PGE2, carrageenin, bradykinin, TNF-α, IL-6, IL-8 and dopamine (Ferreira et al. 1997). ...
... Dexamethasone inhibited significantly (p<0.001) with NO production from control rat. A study by Yang et al. (1998) also supported the role of ANXA1 in blocking NO production upon glucocorticoid treatment. When topical glucocorticoid was given, the same result indicated that it was induced by ANXA1. ...
Inflammation is a body response towards any injury or tissue damage. It involves the accumulation of neutrophils and release of inflammatory mediators. ANXA1, a 37 kDa glucocorticoid inducible protein plays an important role in resolving inflammation. The unique N-terminal and its mimetic peptide exert strong anti-inflammatory actions. This study was conducted to review the roles of ANXA1 in inflammation and identify any other reported roles. Electronic search was done whereby a total of 3797 articles were located from three databases, namely Ovid MEDLINE, Science Direct, and PubMed. Articles on ANXA1 and inflammation were selected based on inclusive criteria and review papers were excluded. Bias analysis was performed based on bias risk tool and 27 articles were included in the study. It was found that ANXA1 was able to resolve inflammation in many inflammatory diseases. Upon treatment with glucocorticoid, ANXA1 is induced and its significant expressions in tissues are important in resolving inflammation. However, this effect can be reversed by administering an anti-annexin antibody. This protein also acts on members of all formyl peptide receptors (FPR) and activates them to initiate reaction. It acts mainly by causing the death of neutrophils through apoptosis. In addition, ANXA1 is identified as a marker in cancer cells which determines the survival rates. In conclusion, ANXA1 is a key modulator in resolving inflammation in many diseases and is actively being induced upon glucocorticoid treatment.
... 1,3 Recently, we observed that ANXA1 is also constitutively expressed in a human lymphoblastic T cell line, the CCRF-CEM cell line. 4 Although its biological role is still incompletely characterised, ANXA1 is considered an endogenous anti-inflammatory effector that mediates at least some of the anti-inflammatory actions of the glucorticoid (GC) hormones; namely, the inhibition of phospholipase A 2 , with the consequent suppression of prostaglandin and leukotriene production, 1 the inhibition of superoxide generation, 5 the inhibition of the activation, transmigration and phagocytic ability of neutrophils. 3 Recently, ANXA1 has also been shown to mediate the inhibitory effect of GCs on the expression of cyclooxygenase-2 (COX-2), 6 Á 8 an enzyme required for prostaglandin production and also involved in cell proliferation. ...
... Once in the extracellular medium, ANXA1 binds, in a paracrine or autocrine way, to specific plasma membrane binding sites, which are considered to mediate its biological actions. 5,13 Consistent with the notion that ANXA1 mediates some of the antiinflammatory actions of GCs, these hormones, most remarkably the synthetic GC dexamethasone (Dex), have been shown to potently induce ANXA1 secretion and synthesis in many different cells. 14,15 Our own observations also show that both Dex 16 and E 2 b 4 induce the rapid secretion of ANXA1, followed by its de novo synthesis, in the human lymphoblastic CCRF-CEM cells. ...
Annexin 1 (ANXA1), a member of the annexin family of calcium-binding and phospholipid-binding proteins, is a key mediator of the anti-inflammatory actions of steroid hormones. We have previously demonstrated that, in the human lymphoblastic CCRF-CEM cell line, both the synthetic glucocorticoid hormone, dexamethasone (Dex), and the estrogen hormone, 17beta-estradiol (E2beta), induce the synthesis of ANXA1, by a mechanism independent of the activation of their nuclear receptors. Recently, it was reported that the gene coding for ANXA1 contains acAMP-responsive element (CRE). In this work, we investigated whether Dex and E2beta were able to induce the activation of CRE binding proteins (CREB) in the CCRF-CEM cells. Moreover, we studied the intracellular signalling pathways involved in CREB activation and ANXA1 synthesis in response to Dex and E2beta; namely, the role of cAMP and the p38 mitogen activated protein kinase (MAPK).
The results show that Dex and E2beta were as effective as the cAMP analogue, dBcAMP, in inducing CREB activation. On the contrary, dBcAMP induced ANXA1 synthesis as effectively as these steroid hormones. Furthermore, the cAMP antagonist, Rp-8-Br-cAMPS, and the specific p38 MAPK inhibitor,SB203580, effectively prevented both Dex-induced, E2beta-induced and dBcAMP-induced CREB activation and ANXA1 synthesis.
Taken together, our results suggest that,in CCRF-CEM cells, Dex-induced and E2beta-inducedANXA1 expression requires the activation of the transcription factor CREB, which in turn seems to be mediated by cAMP and the p38 MAPK. These findings also suggest that, besides the nuclear steroid hormone receptors, other transcription factors, namely CREB, may play important roles in mediating the anti-inflammatory actions of glucocorticoids and oestrogen hormones.
... The serum was not added since several samples of tested serum contained endotoxin which strongly stimulated synovial membrane and masked effect of LPS. Up to now in vitro studies on the reaction of the synovial membranes on different stimuli were limited to the pathological material either from patients with rheumatoid arthritis [4] [6] or from hind feet joints of rats with adjuvant arthritis [5] [9] [10]. Thus, as far as we could establish, we are presenting for the first time a method of culture of normal synovium and also we demonstrate that synovium produces in vitro cytokines and responds to stimulatory action of LPS. ...
... Up to now in vitro studies on the reaction of the synovial membranes on different stimuli were limited to the pathological material either from patients with rheumatoid arthritis [4,6] or from hind feet joints of rats with adjuvant arthritis [5,9,10]. Thus, as far as we could establish, we are presenting for the first time a method of culture of normal synovium and also we demonstrate that synovium produces in vitro cytokines and responds to stimulatory action of LPS. ...
The objective of this work was to devise an in vitro system for studies on cytokine secretion by synovial membrane treated as a whole organ with various synoviocyte populations. Synovial membrane from knee joints of WAG rats was dissected and incubated in culture medium without serum for 4 - 48 h. The level of IL-1alpha was determined in synovial lysates and IL-6 in culture medium. The synovial membrane from left and right knee joint of the same rat produced similar amount of cytokines both in lysates and in the medium. Synovial membrane stimulated by LPS for 4 or 24 h gave significantly stronger cytokine response than the membrane from the opposite (control) knee. After 48 h incubation of synovial membrane drastic drop in cytokine level was noted, which indicated on deterioration of the membranes. The test may be useful in studies on factors affecting cytokine secretion by synoviocytes.
... Arthritis was induced in rats by injecting complete Freund's adjuvant (CFA, 100 μl) containing heat-killed Mycobacterium tuberculosis into the right hind paw of rats (Sigma Aldrich, MA, USA). After induction, synovial macrophages were isolated as described previously with minor modifications (Yang et al., 1998). In brief, fresh synovial tissues were isolated from arthritic rats on day 19 and were subjected to collagenase treatment (0.4% collagenase containing complete DMEM medium) under aseptic conditions. ...
The current study was designed to explore the underlying therapeutic effect of berberine (BBR), an alkaloid compound against LPS (1 μg/ml)/TNFα (10 ng/ml) mediated apoptosis signal-regulating kinase 1 (ASK1) signaling in RAW 264.7 macrophages and adjuvant-induced arthritic synovial macrophages (AA-SM) with relation to miR-23a levels. LPS and TNFα stimulation abrogated the expression of miR-23a resulting in TLR4/TRAF2 mediated
ASK1 activation and downstream phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). BBR (25–75 μM) treatment ameliorated the gene expression levels of TLR4, TRAF2, TNFα, IL-6, and IL-23 through the upregulation of miR-23a. Subsequently, BBR suppressed the levels of TLR4/TRAF2 mediated phosphorylation of ASK1/p38 and attenuated the expression of various pro-inflammatory cytokines (TNFα, IL-6 & IL-23) in RAW 264.7 macrophages and AA-SM cells. BBR was able to counteract these factors through activation of miR-23a levels in LPS/TNFα stimulated RAW 264.7 macrophages and AA-SM cells. NQDI1 (30 μM) treatment inhibited ASK1 activation resulting in basal levels of miR-23a, owing to the conclusion that ASK1 activation downregulates miR-23a levels inside the cells. Overall, our current findings predict that BBR is a potential candidate for therapeutic targeting of TLR4/TRAF2 mediated ASK1 activation in inflammatory and in RA pathogenesis possibly through post-transcriptional gene silencing via upregulation of miR-23a.
... nNOS was induced by dexamethasone but not for thrombin; in contrast, thrombin repressed the induction of nNOS produced by dexamethasone. It is known that dexamethasone produces different effects on iNOS: inhibition of iNOS induced in different cells, as macrophages (Walker et al., 1997) and glioma cells (Simmons and Murphy, 1993;Rieger et al., 1998;Tawara et al., 1998;Shinoda et al., 2003), or suppression of iNOS expression in synovial macrophages (Yang et al., 1998). Similarly, dexamethasone administration in kidney was associated with a 5-fold increase of eNOS expression and a 3-fold increase of iNOS expression in renal cortex (Bobadilla et al., 1999). ...
... 2.6. Extraction, collection, and separation of primary synovial macrophages from joint tissue Joint samples were processed and synovial macrophages were extracted according to the previously established methods with slight modification [26,27]. Upon sacrificing the animals, the hind paw tissues were excised, phalanges were removed, and tissue samples were collected from a total of five animals and cut into small pieces. ...
... Joint samples were processed and synovial macrophages were extracted according to the previously established methods with slight modification [26,27]. Upon sacrificing the animals, the hind paw tissues were excised, phalanges were removed, and tissue samples were collected from a total of five animals and cut into small pieces. ...
In this study, we have shown for the first time the effectiveness of a non-viral gene transfection strategy to re-polarize macrophages from M1 to M2 functional sub-type for the treatment of rheumatoid arthritis (RA). An anti-inflammatory (IL-10) cytokine encoding plasmid DNA was successfully encapsulated into non-condensing alginate based nanoparticles and the surface of the nano-carriers was modified with tuftsin peptide to achieve active macrophage targeting. Enhanced localization of tuftsin-modified alginate nanoparticles was observed in the inflamed paws of arthritic rats upon intraperitoneal administration. Importantly, targeted nanoparticle treatment was successful in reprogramming macrophage phenotype balance as ∼66% of total synovial macrophages from arthritic rats treated with the IL-10 plasmid DNA loaded tuftsin/alginate nanoparticles were in the M2 state compared to ∼9% of macrophages in the M2 state from untreated arthritic rats. Treatment significantly reduced systemic and joint tissue pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) expression and prevented the progression of inflammation and joint damage as revealed by magnetic resonance imaging and histology. Treatment enabled animals to retain their mobility throughout the course of study, whereas untreated animals suffered from impaired mobility. Overall, this study demonstrates that targeted alginate nanoparticles loaded with IL-10 plasmid DNA can efficiently re-polarize macrophages from an M1 to an M2 state, offering a novel treatment paradigm for treatment of chronic inflammatory diseases.
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... Several inflammatory mediators produced by macrophages during the inflammatory response such as TNF- (Sudlow et al., 1996), PGE 2 (Sudlow et al., 1996) and NO (Yang et al., 1998) can be inhibited by GCs in an AnxA1-dependent manner. It has been suggested that the inhibition of NO release and the expression of iNOS in the macrophages are associated with the increase of IL-10 and the decrease in IL-12mRNA (Ferlazzo et al., 2003). ...
... Glucocorticoid stimulation causes annexin A1 mobilization to the cell surface and secretion where it mediates glucocorticoid induced anti-inflammatory effects. This is of particular interest in arthritis as glucocorticoid therapy is one of the current treatments for this condition (Flower, 1988;Podgorski et al., 1992;Yang et al., 1998Yang et al., , 1999Maderna et al., 2005). However, as is increasingly the case for many mediators, the role of annexin A1 may not be as unambiguous as initially described and it may also potentiate pro-inflammatory actions in arthritis. ...
Synovial macrophages are one of the resident cell types in synovial tissue and while they remain relatively quiescent in the healthy joint, they become activated in the inflamed joint and, along with infiltrating monocytes/macrophages, regulate secretion of pro-inflammatory cytokines and enzymes involved in driving the inflammatory response and joint destruction. Synovial macrophages are positioned throughout the sub-lining layer and lining layer at the cartilage–pannus junction and mediate articular destruction. Sub-lining macrophages are now also considered as the most reliable biomarker for disease severity and response to therapy in rheumatoid arthritis (RA). There is a growing understanding of the molecular drivers of inflammation and an appreciation that the resolution of inflammation is an active process rather than a passive return to homeostasis, and this has implications for our understanding of the role of macrophages in inflammation. Macrophage phenotype determines the cytokine secretion profile and tissue destruction capabilities of these cells. Whereas inflammatory synovial macrophages have not yet been classified into one phenotype or another it is widely known that TNFα and IL-l, characteristically released by M1 macrophages, are abundant in RA while IL-10 activity, characteristic of M2 macrophages, is somewhat diminished. Here we will briefly review our current understanding of macrophages and macrophage polarization in RA as well as the elements implicated in controlling polarization, such as cytokines and transcription factors like NFκB, IRFs and NR4A, and pro-resolving factors, such as LXA4 and other lipid mediators which may promote a non-inflammatory, pro-resolving phenotype, and may represent a novel therapeutic paradigm.
... nNOS was induced by dexamethasone but not for thrombin; in contrast, thrombin repressed the induction of nNOS produced by dexamethasone. It is known that dexamethasone produces different effects on iNOS: inhibition of iNOS induced in different cells, as macrophages (Walker et al., 1997) and glioma cells (Simmons and Murphy, 1993;Rieger et al., 1998;Tawara et al., 1998;Shinoda et al., 2003), or suppression of iNOS expression in synovial macrophages (Yang et al., 1998). Similarly, dexamethasone administration in kidney was associated with a 5-fold increase of eNOS expression and a 3-fold increase of iNOS expression in renal cortex (Bobadilla et al., 1999). ...
Anti-inflammatory strategies receive growing attention for their potential to prevent pathological deterioration in disorders such as Parkinson's disease, which is accompanied by inflammatory reactions that might play a critical role in the degeneration of nigral dopaminergic neurons. We investigated the influence of dexamethasone - a potent synthetic member of the glucocorticoids class of steroid hormones that acts as an anti-inflammatory - on the degeneration of the dopaminergic neurons of rats observed after intranigral injection of thrombin, a serine protease that induces inflammation through microglia proliferation and activation. We evaluated tyrosine hydroxylase (TH)-positive neurons as well as astroglial and microglial populations; dexamethasone prevented the loss of astrocytes but was unable to stop microglial proliferation induced by thrombin. Moreover, dexamethasone produced alterations in the levels of nexin and the thrombin receptor PAR-1, and facilitated accumulation of alpha-synuclein induced by thrombin in dopaminergic neurons. Dexamethasone increased oxidative stress and expression of monoamine oxidase A and B, along with changes on different MAP kinases related to degenerative processes, resulting in a bigger loss of dopaminergic neurons after intranigral injection of thrombin in dexamethasone-treated animals. It is interesting to ascertain that inhibition of monoamine oxidase by tranylcypromine prevented neurodegeneration of dopaminergic neurons, thus suggesting that the deleterious effects of dexamethasone might be mediated by monoamine oxidase.
... Complementing these studies are a number of reports demonstrating comparable immunologic effects of glucocorticoids and rolipram on cytokine induction (decreased TNF-␣ and increased interleukin (IL)-10 and IL-4) as well as inflammation (e.g. reduced macrophage activation and nitric oxide production) (Sekut et al. 1995;Eigler et al. 1998;Sternberg 2001;Abbas et al. 2000;Daynes and Araneo 1989;Yang et al. 1998;Beshay et al. 2001;Swain et al. 1999;Gayo et al. 1998). Moreover, there have been two recent reports of synergistic actions of glucocorticoids and rolipram on the release of eotaxin, a potent eosinophil chemoattractant, from human airway smooth muscle cells Knox 2000, 2001). ...
Previous studies have demonstrated that antidepressants can enhance glucocorticoid receptor (GR) translocation and function, possibly through activation of cAMP and downstream cAMP dependent protein kinases. Accordingly, we examined GR function in cells treated with rolipram, a phosphodiesterase (PDE) type 4 inhibitor that antagonizes cAMP breakdown. Compared with vehicle-treated cells, rolipram alone and in combination with dexamethasone significantly enhanced GR function as measured in both mouse L929 cells and rat C6 glioma cells stably transfected with reporter genes driven by upstream glucocorticoid response elements. Rolipram's facilitation of GR function was reversible by the GR antagonist, RU486, and was associated with reduced cytosloic GR binding, indicating rolipram enhancement of GR nuclear translocation. Finally, rolipram potently augmented GR enhancement by the antidepressant, desipramine. These findings broaden the potential pathways by which PDE type 4 inhibitors can influence cellular function and indicate that these agents may have special utility in disorders associated with impaired GR-mediated feedback inhibition.
... Dexamethasone suppresses iNOS expression in the peritoneal exudate PMNs in presence of L-arginine (20) resulting from the reversible effect of L-arginine on the nicotine-induced deceasing effect on the plasma exudation. Yang et al. reported that dexamethasone inhibits NO production without decreasing iNOS expression via lipocortin 1, an anti-inflammatory peptide induced by glucocorticoid in adjuvant arthritis synovial macrophages (39). Considering that immunological inflammation such as the Arthus reaction could initiate and/ or promote chronic inflammatory disorders including rheumatoid arthritis and that the suppression of the immunological inflammations by anti-inflammatory steroids plays an important role in their clinical effect (40 -45), lipocortin 1 might be responsible for the anti-inflammatory action of nicotine-induced release of endogenous corticosterone on the PSAR. ...
To elucidate the anti-inflammatory action of nicotine-induced corticosterone elevation on the passive skin Arthus reaction (PSAR), we investigated the inflammatory process in the PSAR. The polymorphonuclear leukocyte (PMNs) infiltration was observed just before as well as after elicitation by measuring extractable myeloperoxidase. The plasma exudation was significantly inhibited by anti-rat tumor necrosis factor (TNF)-alpha antibody (5 microg/site, i.d.) at the time of sensitization or by superoxide dismutase (52500 units/kg, i.p.) 1 h before elicitation or N(G)-nitro-L-arginine-methyl ester (100 mg/kg, i.v.) just at elicitation. Pretreatment with a single injection of nicotine (0.8 mg/kg, i.p.) 30 min before elicitation suppressed the plasma exudation but not the PMNs infiltration. This nicotine-induced decreasing effect was abolished in animals supplemented with L-arginine (300 mg/kg, i.v.) just at elicitation. The production of nitric oxide (NO) in peritoneal PMNs derived from an animal injected peritoneally with oyster glycogen was significantly suppressed by pretreatment with nicotine (0.8 mg/kg, i.v.) 30 min prior to harvesting. This inhibitory action of nicotine was abolished in animals pretreated with mifepristone (30 mg/kg, s.c.), a glucocorticoid receptor antagonist. These findings indicate that a single systematic administration of nicotine may attenuate the plasma exudation in the PSAR by suppressing the production of NO in the PMNs primed with TNF-alpha via nicotine-induced endogenous glucocorticoid.
... From 48 h of duct ligation onwards, glandular atrophy becomes obvious with secretory cell degranulation (Osailan et al, 2006b), which develops to a progressive decrease in secretory function and gland weight (Martinez et al, 1982). Dexamethasone has been used in different studies, whenever it is desirable to limit inflammation and prevent tissue destruction (Jick et al, 1965; Masferrer et al, 1990; Adesanya et al, 1996; Yang et al, 1998; Perretti et al, 2002). This glucocorticoid inhibits the generation of eicosanoids and superoxide anion and is also a potent suppressor of iNOS expression (Robbins et al, 1994). ...
The commonly associated aetiology of salivary gland inflammation and salivary hypofunction has led to the widely held belief that inflammation causes salivary gland hypofunction. Indeed, our own recent study seemed to support this contention. Here, we tested the hypothesis that, in an acute duct ligation model, eliminating inflammation the submandibular gland would recover normal function.
Ligation of the rat submandibular gland excretory duct for 24 h was used to induce inflammation and salivary gland hypofunction. A group of duct ligated rats was compared with a second group given dexamethasone, on the day of duct ligation. Twenty-four hours later salivary gland function was assessed and salivary glands were collected.
Histology and myeloperoxidase activity assay revealed a profound decrease in inflammatory cell infiltration of ligated glands from rats given dexamethasone, compared with ligated glands in the absence of dexamethasone. Salivary flow rate evoked by methacholine was decreased (P < 0.01) by approximately 56% (ligated vs control, 79 +/- 9 microl min(-1) g(-1)vs 177 +/- 11 microl min(-1) g(-1)) and salivary flow from ligated dexamethasone-treated and ligated glands was similar.
Despite eliminating the inflammatory reaction in the ligated gland, salivary hypofunction was not reversed, suggesting that other mechanisms must be at work in the ligation-induced salivary hypofunction.
... This is supported by studies in animal models of arthritis in which, for example, an Anx-1 N-terminal peptide mimicked the antiinflammatory actions of GCs in experimental arthritis (18). In contrast, anti–Anx-1 antibodies exacerbated clinical disease in carrageenin-and adjuvant-induced arthritis, accompanied by elevated synovial production of prostaglandin E 2 and TNF (18,19,26). Moreover, in both of those models, Anx-1 was shown to be necessary for the antiinflammatory effect of exogenous dexamethasone , in that Anx-1 neutralization prevented the effect of dexamethasone (18,19). ...
Annexin 1 (Anx-1) is a putative mediator of the antiinflammatory actions of glucocorticoids (GCs). This study investigated the role of Anx-1 in experimental arthritis and in GC-mediated inhibition of inflammation, using antigen-induced arthritis (AIA) in Anx-1 knockout (Anx-1(-/-)) mice.
Arthritis was induced by intraarticular injection of methylated BSA (mBSA) in mice preimmunized with mBSA. Disease was assessed after 7 days by histologic examination of the knee joints. Serum levels of anti-mBSA IgG were determined by enzyme-linked immunosorbent assay. Cytokine messenger RNA (mRNA) expression was detected by real-time polymerase chain reaction.
A significant exacerbation of arthritis was observed in the Anx-1(-/-) mice compared with wild-type (WT) mice. This was associated with increased mRNA expression of synovial interleukin-1 beta, tumor necrosis factor alpha, interleukin-6, and macrophage migration inhibitory factor. Dexamethasone significantly reduced the histologic severity of synovitis and bone damage in the WT mice, but exerted no inhibitory effects in the Anx-1(-/-) mice, and also significantly reduced the serum levels of anti-mBSA IgG and the numbers of peripheral blood neutrophils and lymphocytes in WT mice, but had no such effect in Anx-1(-/-) mice.
Anx-1 exerts endogenous antiinflammatory effects on AIA via the regulation of cytokine gene expression, and also mediates the antiinflammatory actions of dexamethasone in AIA.
In order to develop a better therapeutic approach for the treatment of rheumatoid arthritis (RA), withaferin-A; a steroidal lactone incorporated with mannosylated liposomes (ML-WA) was administered to adjuvant induced arthritic rats in order to target the synovial macrophages. The confocal microscopy studies showed a successful internalization of ML-WA in the primarily isolated synovial macrophages. Consequently, targeting synovial macrophages via ML-WA reduced the oxidative stress (ROS and NO), and paw edema, however, a progressive gain in the body weight was observed in AIA rats. ML-WA treatment upregulated the production of osteoprotegerin (OPG) and downregulated the release of receptor activator of nuclear factor-κB ligand (RANKL), favoring osteoclastogenesis negatively. Correspondingly, the ankle joints were found intact with no bone erosion and cartilage degradation in ML-WA treated AIA rats as evidenced by histopathological analysis. Also, synovial macrophage assessment showed that the concentration and the gene amplification of M1 macrophage mediated pro-inflammatory mediators (TNF-α, IL-1β, IL-6, MCP-1 and VEGF) were curtailed in ML-WA treated AIA rats. In contrast, anti-inflammatory cytokine (IL-10) was found abundantly released. Furthermore, the mRNA expression of the M1 surface marker (CD86) was found down regulated, whereas, M2 marker (CD163) was highly amplified in ML-WA treated synovial macrophages of arthritic rats. Cumulatively, our result signified that targeted delivery of ML-WA ameliorated the severity of inflammation and bone resorption in AIA rats via M1 to M2 macrophage repolarization.
The purpose of the study was to develop a liposomal drug delivery system for morin, a dietary polyphenol, in order to target the synovial macrophages and investigate the remission of disease severity in the adjuvant-induced arthritic (AIA) rats. To do so, mannose decorated liposomal morin (ML-Morin) was prepared using the thin film hydration method and the physicochemical properties were characterized. The particle size and zeta potential of liposomal morin (L-Morin) was found to be 127.9nm ± 2.6 and -24.5mV ± 0.76, whereas ML-Morin showed an increased value of 132.5nm ± 5.2 and -54.8mV ± 0.67 respectively. Further, the drug entrapment efficiency (% EE) of ML-Morin was found 86.7 ± 3.8%. To understand the efficacy of L-Morin, ML-Morin over free-Morin; cellular uptake, production and expression of pro-inflammatory mediators, osteoclastogenic factors, and transcription factors were evaluated in primarily isolated synovial and spleen macrophages. Interestingly, confocal microscopic images showed an increased uptake of ML-Morin in the synovial and spleen macrophages than L-morin. In addition, ML-Morin significantly suppressed the production and mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-17), angiogenic factors (VEGF), an inflammatory enzyme (iNOS), and transcription factor (NF-κB-p65). Furthermore, the protein expression of TNF-α, IL-1β, IL-6, IL-17, RANKL, STAT-3, and p-STAT-3 was found to decrease with increased osteoprotegerin (OPG) expression in the ML-Morin targeted macrophages. Thus, our findings endorsed that, ML-Morin preferential internalization into the macrophages of arthritic rats effectively inhibited the inflammatory immune response and osteoclastogenesis better than the dexamethasone palmitate encapsulated mannosylated liposomes (ML-DP), a reference drug as evidenced by clinical and histological analysis.
These anti-inflammatory drugs that are used to treat acute gout are discussed in detail. Their administration, pharmacology, and toxicity are considered. Then, urate-lowering therapy is thoroughly described, again considering the administration, pharmacology, and toxicity of these agents. The widespread mismanagement of gout in general and even specialty medical practice makes this information important for patients and their physicians.
A complete set of integral equations is used to describe the kinetics of reversible photo-ionization after instantaneous excitation, including “geminate” and bimolecular charge recombination to either the ground or excited states of neutral reactants. The excitations restored by bimolecular recombination of ions produce the delayed fluorescence which goes to zero as a second power of time.
The fluorescence kinetics previously obtained with the spin-less Integral Encounter Theory (IET) and distant dependent rates of electron transfer is essentially corrected using Modified Encounter Theory (MET). The delayed fluorescence dependence on conversion rate is explained analytically on the simpler example of contact ionization and recombination.
Aim: To investigate effect of bizhongxiao decoction (BZXD) on changes of protein in synovitis of rats with collagen-induced arthritis (CIA) and analyse mechanism of BZXD on treating rheumatoid arthritis (RA). Methods: The experiment was completed in the Institute of Combined Traditional Chinese Medicine and Western Medicine, Xiangya Hospital of Central South University and Key Laboratory of Tumor Protein of Ministry of Public Health between May 2004 and February 2005. Totally 70 SD rats were divided randomly into 3 groups. Ten rats were regarded as normal group, and other 60 rats were modeled by type II collagen and complete Freunds adjuvant. Successful rat models were selected and divided into BZXD group and model group. BZXD was consisted of 15 kinds of Chinese herbs such as baihuashe shecao 15g, zhonjiefeng 30 g, danshen 15 g, luoshiteng 20 g, gusuibu 15 g, yimi 30 g, etc., and fried with double distilled water for twice with 30 minutes each time. Then, liquid was mixed, filtered with G4 filter and concentrated in water bath at 60°C with 116 g raw materials in each milliliter. Rats in BZXD group were perfused with 10 mL/kg BZXD (equal to 62.1 g raw materials) twice a day; rats in model group were perfused with 10 mL/kg saline twice a day; rats in normal group were drunk water freely. The total proteins of synovial tissue of rats in normal group, model group and BZXD group were separated by two-dimensional gel electrophoresis (2-DE), respectively. Then gets were stained by Coomassie brilliant blue, scanned by Image Scanner. Relative abundance of the protein spots was calculated by comparing spots density volume on the gel. The differentially expressed protein spots were identified by peptide mass fingerprint (PMF) based on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and database searching, then some of them were validated by western blotting. Results: Among 70 rats, 7 were lost because of unsuccessful modeling, and totally 63 rats, 26 in BZXD group, 27 in model group and 10 in control group, entered the final analysis. 1 Reproducible 2DE maps of synovial tissue were established in normal group, experimental arthritis model group and BZXD group respectively, the average spots of protein were 947±39, 994±41 and 1 031±52 respectively, and the match rates were 92%, 91% and 94.2%. 2 Totally 55 protein spots were twice than expression of synovial tissue in normal group, experimental arthritis model group and BZXD group. This suggested that the functions of these proteins involved in metabolism, energy generation, transportation, anti-oxidation, signal transduction and protein folding etc. Then the different expressions of annexin 1 and aldolase A in normal group, experimental arthritis model group and BZXD group by western blotting were similar to those of proteomic results. Conclusion: Synovium of joint of rheumtoid arthritis is a complex process which is involved by multiple proteins. Histological analysis of proteins in synovium tissue is one of methods for screening related protein of lesion. Annexin 1 and aldolase A are related to CIA synovitis, and BZXD has a good effect on CIA by regulating protein expression of synovial tissue of rats.
Drugs exhibiting anti-inflammatory and analgesic properties have been clinically used in the management of pain and impairment of joint functions in arthritis. In view of available studies on the beneficial effect of artesunate in various inflammatory conditions, the present study was carried out to evaluate its efficacy in ameliorating functional limitations of arthritis and to understand the underlying mechanisms. The study was carried out in rat model of Freund's complete adjuvant-induced monoarthritis where artesunate was found to produce a dose-dependent reduction in joint inflammation, improvement in functional parameters like stair climbing ability, motility, and suppression of mechanical allodynia at the doses of 50 and 150 mg/kg. Our study shows that protection afforded by artesunate was brought about by decreasing the levels of nitric oxide, influx of neutrophils, maintenance of oxidative homeostasis, inhibition of COX-2 expression, and apoptosis. Further, histological analysis of the arthritic joints also substantiated the anti-inflammatory property of artesunate. Thus, our study shows that artesunate has a potential for use in the treatment of arthritis.
Since primeval times, the inflammatory process has been described in many different ways. Several anti-inflammatory therapies have been used in different biological models. However, in a recent "back to nature move", modern man is searching for natural products with medicinal properties, particularly those obtained from plants and bees. Propolis has been used in folk medicine for a very long time. The many compounds present in propolis require investigation.Physical-chemical analysis studies have not sufficiently established quality standards of propolis containing products. These standards should depend especially on their different pharmacological activities. There are few studies reporting on the in vitro anti-inflammatory activity of propolis containing products. It is necessary to evaluate the anti-inflammatory potential of commercial products containing propolis.
A mathematically rigorous scaling procedure for the derivation of binary non-Markovian kinetic equations has been developed. Though the procedure refers to the irreversible reaction A+B→B, it can serve as a reliable basis for selecting diagrams in regular many-particle derivation of non-Markovian kinetic equations for other types of elementary chemical reactions in liquid solutions.
Rheumatoid arthritis is a chronic systemic inflammatory disease where cardiovascular diseases have been recognized as major determinants of early morbidity and mortality. Recently, there has been renewed interest in medication with glucocorticoids to decrease joint damage, but in long-term they incur substantial increase in the risk of cardiovascular diseases and their overall risk/benefit ratio is deemed unfavorable. So, the proposed role of statins in treatment of rheumatoid arthritis when corticosteroids indicated as traditional therapy needs to be investigated. Fifty albino rats were divided into 5 equal groups; normal control group, Freund's adjuvant induced arthritis group, group of induced arthritis treated with atorvastatin, group of induced arthritis treated with prednisolone, and group of induced arthritis treated with atorvastatin and prednisolone. The change in paw volume, serum levels of malondialdehyde (MDA), paraoxonase1 (PON1) activity, nitrites, C-reactive protein (CRP) and lipid profile was determined. The results revealed that treatment by atorvastatin in combination with prednisolone produced better satisfactory results than in either remedy alone evidenced by significant decrease in volume of hind paw, levels of MDA, nitrites, CRP, significant increase in PON1 activity and HDL and amelioration of other lipid profile parameters that were impaired by prednisolone. The present work demonstrated that statins exert beneficial anti-inflammatory and antioxidant effects beyond their basic cholesterol-lowering activity. Thus, we suggest that if corticosteroid therapy is indicated in rheumatoid arthritis, atorvastatin could be added to get benefit from its pleiotropic effects. However, further studies are needed to verify to what extent statin therapy contribute to clinical benefits in human.
We previously reported that 6-shogaol, a phenolic compound from ginger has antiinflammatory properties in a Complete Freund's Adjuvant (CFA) model of mono-arthritic rats. In the present study, we investigated the effects of 6-shogaol on the production of inflammatory mediators from lipopolysaccharide (LPS) activated RAW 264.7 macrophages. These mediators (TNF-alpha, IL-1-beta and NO) and their output from macrophages are involved in various pathophysiological events of chronic inflammation and arthritis.
Effects of 6-shogaol were investigated on the production of the mediators TNF-alpha, IL-1-beta and NO (measured as nitrate)from macrophages. Lipopolysaccharide activated RAW 264.7 macrophages were cultured in the presence and absence of 6-shogaol (2 microM, 10 microM and 20 microM) and ELISA was used to quantify the output of the mediators.
6-shogoal (2 microM, 10 microM and 20 microM) significantly inhibited the production of nitric oxide (NO), IL-1beta and TNF-alpha from the LPS activated RAW264.7 macrophages.
The results suggest that macrophages are targets for the anti-inflammatory effects of 6-shogaol. Also, the inhibitory effects against TNF-alpha, IL-1beta and NO production from LPS activated macrophages are cellular mechanisms by which 6-shogaol produced its anti-inflammatory effects. These mechanisms provide an explanation of the protection by 6-shogaol against development of joint inflammation and cartilage degradation in CFA induced mono-arthritis that we previously demonstrated (1). Based on these results with 6-shogaol, there is evidence that it exhibits exploitable anti-inflammatory properties.
Annexin I is a glucocorticoid-induced mediator with anti-inflammatory activity in animal models of arthritis. We studied the effects of a bioactive annexin I peptide, ac 2–26, dexamethasone (DEX), and interleukin-1β (IL-1β) on phospholipase A2 (PLA2) and cyclooxygenase (COX) activities and
prostaglandin E2 (PGE2) release in cultured human fibroblast-like synoviocytes (FLS). Annexin I binding sites on human osteoarthritic (OA) FLS were detected by ligand binding flow cytometry. PLA2 activity was measured using 3H-arachidonic acid release, PGE2 release and COX activity by ELISA, and COX2 content by flow cytometry. Annexin I binding sites were present on human OA FLS. Annexin I peptide ac 2–26 exerted a significant concentration-dependent inhibition of FLS constitutive PLA2 activity, which was reversed by IL-1β. In contrast, DEX inhibited IL-1β-induced PLA2 activity but not constitutive activity. DEX but not annexin I peptide inhibited IL-1β-induced PGE2 release. COX activity and COX2 expression were significantly increased by IL-1β. Annexin I peptide demonstrated no inhibition of constitutive or IL-1β-induced COX activity. DEX exerted a concentration-dependent inhibition of IL-1β-induced but not constitutive COX activity. Uncoupling of inhibition of PLA2 and COX by annexin I and DEX support the hypothesis that COX is rate-limiting for PGE2 synthesis in FLS. The effect of annexin I but not DEX on constitutive PLA2 activity suggests a glucocorticoid-independent role for annexin I in autoregulation of arachidonic acid production. The lack of effect of annexin I on cytokine-induced PGE2 production suggests PGE2-independent mechanisms for the anti-inflammatory effects of annexin I in vivo.
The infiltration and persistence of hematopoietic immune cells within the rheumatoid arthritis (RA) joint results in elevated levels of pro-inflammatory cytokines, increased reactive oxygen (ROS) and -nitrogen (RNS) species generation, that feeds a continuous self-perpetuating cycle of inflammation and destruction. Meanwhile, the controlled production of ROS is required for signaling within the normal physiological reaction to perceived "foreign matter" and for effective apoptosis. This review focuses on the signaling pathways responsible for the induction of the normal immune response and the contribution of ROS to this process. Evidence for defects in the ability of immune cells in RA to regulate the generation of ROS and the consequence for their immune function and for RA progression is considered. As the hypercellularity of the rheumatoid joint and the associated persistence of hematopoietic cells within the rheumatoid joint are symptomatic of unresponsiveness to apoptotic stimuli, the role of apoptotic signaling proteins (specifically Bcl-2 family members and the tumor suppressor p53) as regulators of ROS generation and apoptosis are considered, evaluating evidence for their aberrant expression and function in RA. We postulate that ROS generation is required for effective therapeutic intervention.
Annexin-1 (ANXA1) is a mediator of the anti-inflammatory actions of endogenous and exogenous glucocorticoids (GC). The mechanism of ANXA1 effects on cytokine production in macrophages is unknown and is here investigated in vivo and in vitro. In response to LPS administration, ANXA1(-/-) mice exhibited significantly increased serum IL-6 and TNF compared with wild-type (WT) controls. Similarly, LPS-induced IL-6 and TNF were significantly greater in ANXA1(-/-) than in WT peritoneal macrophages in vitro. In addition, deficiency of ANXA1 was associated with impairment of the inhibitory effects of dexamethasone (DEX) on LPS-induced IL-6 and TNF in macrophages. Increased LPS-induced cytokine expression in the absence of ANXA1 was accompanied by significantly increased LPS-induced activation of ERK and JNK MAPK and was abrogated by inhibition of either of these pathways. No differences in GC effects on MAPK or MAPK phosphatase 1 were observed in ANXA1(-/-) cells. In contrast, GC-induced expression of the regulatory protein GILZ was significantly reduced in ANXA1(-/-) cells by silencing of ANXA1 in WT cells and in macrophages of ANXA1(-/-) mice in vivo. GC-induced GILZ expression and GC inhibition of NF-kappaB activation were restored by expression of ANXA1 in ANXA1(-/-) cells, and GILZ overexpression in ANXA1(-/-) macrophages reduced ERK MAPK phosphorylation and restored sensitivity of cytokine expression and NF-kappaB activation to GC. These data confirm ANXA1 as a key inhibitor of macrophage cytokine expression and identify GILZ as a previously unrecognized mechanism of the anti-inflammatory effects of ANXA1.
Annexin I is a local mediator in neural-endocrine feedback control of inflammation. J. Neurophysiol. 80: 3120-3126, 1998. Activation of primary afferent nociceptors induces a neural endocrine-mediated inhibition of the inflammatory response via a circuit that includes ascending spinal pathways and activation of the hypothalamic-pituitary adrenal (HPA) axis. This circuit inhibits sympathetic neuron-dependent plasma extravasation (PE) in the rat knee joint produced by bradykinin (BK), but not sympathetic neuron-independent PE produced by platelet activating factor (PAF). Noxious (25 mA) but not non-noxious (2.5 mA) electrical stimulation significantly increased plasma corticosterone concentrations, and intravenous infusion of corticosterone (5 micrograms/min) mimicked inhibition of BK-induced PE produced by noxious stimulation. However, perfusion of corticosterone locally through the knee joint, at doses that do not have a systemic action (i.e., </=1 microM), did not inhibit BK-induced PE. Annexin I (lipocortin-1), a 37-kDa member of a family of phospholipid and calcium binding proteins, can mediate local anti-inflammatory effects of glucocorticoids via a mechanism that is partially dependent on inhibition of phospholipase A2 activity and adhesion and transmigration of polymorphonuclear leukocytes. Because BK-induced PE is dependent on both polymorphonuclear leukocytes and phospholipase A2 activity, we tested the hypothesis that the action of corticosterone to inhibit BK-induced PE is mediated by stimulating the production and release of annexin I. Perfusion of BK (150 nM) through the rat knee joint induces a rapid and sustained increase in PE. Co-perfusion of BK with annexin I (100 ng/ml) through the knee joint mimics the inhibition of BK-induced PE produced by noxious electrical stimulation or by intravenous corticosterone. Co-perfusion of BK with annexin I antibody (LCPS1, 1:60 dilution) prevented the inhibition of BK-induced PE produced by noxious electrical stimulation or intravenous corticosterone adminstration. PAF-induced PE, which is not dependent on polymorphonuclear leukocytes, was not inhibited by local perfusion of annexin I. These data suggest that the inhibitory effect of C-fiber activity on BK-induced PE, acting via an HPA circuit, is mediated by annexin I in the knee joint.
Annexin I is a glucocorticoid-inducible protein whose expression in rheumatoid synovium and inhibitory actions in animal models of arthritis suggests its involvement in human arthritis. The present study explored the potential for annexin I to mediate its antiinflammatory actions via specific cell-surface binding sites on human fibroblast-like synoviocytes (FLS).
Annexin I binding sites on cultured FLS from patients with osteoarthritis (OA) and rheumatoid arthritis (RA) were determined by ligand-binding flow cytometry. Phospholipase A2 (PLA2) activity was determined by arachidonic acid release.
FLS exhibited saturable, concentration-dependent cell-surface annexin I binding, with >99% of the OA FLS exhibiting binding at an annexin I concentration of 10 microM. Annexin I binding of RA FLS was significantly lower than that of OA FLS. FLS annexin I binding sites were not affected by elastase or a specific elastase inhibitor, and elastase release did not differ between RA and OA cells. In contrast, collagenase significantly increased annexin I binding sites on OA FLS and approached a significant effect on RA FLS. Tumor necrosis factor alpha increased annexin I binding sites on OA and RA FLS. Similarly, interleukin-1beta significantly increased annexin I binding on OA FLS; but the increased binding on RA FLS was not significant. Dexamethasone exerted no significant effect on OA or RA FLS annexin I binding sites. Treatment of RA FLS with an annexin I N-terminal peptide significantly inhibited RA FLS PLA2 activity.
This is the first description of the expression, regulation, and function of cell surface annexin I binding sites on FLS. Reduced annexin I binding sites in RA FLS may impair the sensitivity of certain proinflammatory events to glucocorticoids.
This review focuses on the role of antiflammins in the regulation of the inflammatory response, in particular acute inflammation. The results show that antiflammins were effective on several classical models of inflammation. Preliminary data suggest that antiflammin action may be due to their ability to suppress leukocyte trafficking to the lesion.
Myocardial reperfusion injury is associated with the infiltration of blood-borne polymorphonuclear leukocytes. We have previous described the protection afforded by annexin 1 (ANXA1) in an experimental model of rat myocardial ischemia-reperfusion (IR) injury. We examined the 1) amino acid region of ANXA1 that retained the protective effect in a model of rat heart IR; 2) changes in endogenous ANXA1 in relation to the IR induced damage and after pharmacological modulation; and 3) potential involvement of the formyl peptide receptor (FPR) in the protective action displayed by ANXA1 peptides. Administration of peptide Ac2-26 at 0, 30, and 60 min postreperfusion produced a significant protection against IR injury, and this was associated with reduced myeloperoxidase activity and IL-1beta levels in the infarcted heart. Western blotting and electron microscopy analyses showed that IR heart had increased ANXA1 expression in the injured tissue, associated mainly with the infiltrated leukocytes. Finally, an antagonist to the FPR receptor selectively inhibited the protective action of peptide ANXA1 and its derived peptides against IR injury. Altogether, these data provide further insight into the protective effect of ANXA1 and its mimetics and a rationale for a clinical use for drugs developed from this line of research.
Leflunomide is now an approved agent for the management of adult rheumatoid arthritis (RA). Its active metabolite A771726 inhibits de novo pyrimidine biosynthesis. Although considered to be an immunosuppressive agent, its mechanism of action remains obscure.
Evaluation of the leflunomide active metabolite A771726 (LEF) effect on interleukin 1beta (IL1beta), tumour necrosis factor (TNFalpha), nitric oxide (NO), and stromelysin (metalloproteinase-3 (MMP-3)) production by activated human synovial tissue in culture.
Synovial tissue was obtained during surgery from patients undergoing total knee replacement owing to RA or osteoarthritis (OA), cut into small pieces, and cultured in Petri dishes with test materials as previously described. IL1beta, TNFalpha, NO, and MMP-3 were measured in the culture media after 48 hours incubation with different doses of LEF by methods previously described.
LEF (0.3, 3, and 9 micro g/ml) inhibited IL1beta production in the presence of lipopolysaccharide (LPS; 3 micro g/ml) in a dose dependent manner (p<0.01) at LEF 0.3 micro g/ml. TNFalpha production in the presence of IL1beta (1 ng/ml) was also inhibited in a dose dependent manner (p<0.05 at LEF 0.3 micro g/ml). NO and MMP-3 production in the presence of LPS (3 micro g/ml) was inhibited as well (p<0.01 at LEF 1 micro g/ml and at LEF 0.3 micro g/ml, respectively). Synovial cell viability evaluated by the tetrazolium salt XTT was unaffected by the LEF concentration used. There was no qualitative difference in the response of OA and RA synovial tissue.
Leflunomide may modulate the rheumatoid articular process by inhibition of local production of IL1beta, TNFalpha, NO, and MMP-3.
Three-dimensional (3D) MR images were obtained from the knees of rats in a model of antigen-induced arthritis, elicited by the intraarticular administration of methylated bovine serum albumin (mBSA) to previously immunized rats. Superparamagnetic particles of iron oxide (SPIO) were administered i.v. 24 hr before each imaging session. Starting 4 days postantigen injection, images from arthritic knees exhibited distinctive signal attenuation in the synovium. This signal attenuation was significantly smaller in knees from animals treated with dexamethasone, a glucocorticosteroid, and completely absent in contralateral knees that had been challenged with vehicle. A significant negative correlation was found between the MRI signal intensity in the synovium and the histologically determined iron content in macrophages located in the same region. These results suggest the feasibility of detecting macrophage infiltration into the knee synovium in this model of antigen-induced arthritis by labeling the cells with SPIO. This readout could provide an early marker of disease progression, before more aggressive changes like cartilage and bone erosion take place. Monitoring early changes associated with arthritis can have an impact in preclinical studies by shortening the duration of the experimental period and by facilitating the investigation of novel immunomodulatory therapies acting on macrophages. Also, the approach can be potentially adapted to clinical studies.
This review will emphasize the concept of anti-inflammation and propose that better understanding of the resolution phase of the inflammatory response organized by the host against inflammatory insults can lead to the identification of novel targets for drug development. Under the umbrella of anti-inflammation, we discuss here recent discoveries in the biology of annexin 1 and glucocorticoids. The fact that annexin 1 and another anti-inflammatory mediator, lipoxin A4, converge onto a specific membrane receptor (termed ALX) might help understanding the resolution phase of inflammation, and strengthen the use of this target for innovative drug development. In addition, glucocorticoids (GC), historically linked to annexin 1, are widely use in the clinical control of several pathologies with an inflammatory etiology, though their use is often burdened by several side effects. The development of new GC with more specific or improved mechanisms, e.g. the nitro-steroids, would go along this wave and, potentially, could be of large applicability. The two mediators/targets here illustrated are to be taken as examples of the clues that the study of anti-inflammation might give to the pharmaceutical industry for innovative drug discovery.
Brain inflammation is accompanied by transection of axons and death of neurons in the acute lesions of multiple sclerosis. We explored mechanisms of inflammatory damage to neurons in vitro using cocultures of rat embryonal cortical neurons with microglia activated by interferon-gamma (IFNgamma) and lipopolysaccharide (LPS). Previously, we have demonstrated that microglia are highly toxic to neurons and that nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) is necessary and sufficient to mediate this toxicity. Here, we show that addition of dexamethasone (1 micro M) to activated cocultures provides effective neuroprotection. We demonstrate that dexamethasone down-regulates NO production of primary microglia by approximately 50% and reduces steady-state iNOS protein and mRNA expression by approximately 70%. These changes were reversed by the glucocorticoid receptor blocker RU-486. Furthermore, we analysed the stability of iNOS protein and show that whilst inhibitors of the proteasome blocked iNOS degradation they did not reverse the dexamethasone effect. Our results indicate that the main mechanism of corticosteroid activity on iNOS is reduction in protein synthesis, not destabilization as previously suggested.
Cytokines induce nitric oxide synthesis by endothelial cells, macrophages and polymorphonuclear leucocytes, indicating a role for nitric oxide in inflammatory processes. Nitric oxide production was therefore measured indirectly as nitrite in serum and synovial fluid samples from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) together with serum samples from healthy volunteers matched for age and sex. Serum nitrite concentrations in patients with RA and OA were significantly higher than in controls. In both disease groups synovial fluid nitrite was significantly higher than serum nitrite, implying nitric oxide synthesis by the synovium. Serum and synovial fluid nitrite concentrations in RA were also significantly higher than those in OA. These data show increased nitric oxide production in RA and OA and suggest a role for nitric oxide as an inflammatory mediator in rheumatic diseases.
Clinical and experimental observations revealed that glucocorticoid-deficient states are associated with an enhanced inflammatory response. The antiinflammatory response of pharmacological doses of glucocorticoids has been tentatively attributed to the induction of lipocortin-I. To determine whether glucocorticoid deficiency causes lipocortin-I down-regulation, the expression of lipocortin-I mRNA and protein was quantified in rats with and without adrenalectomy (ADX). The mRNA of lipocortin-I was quantified by polymerase chain reaction, using a constant amount of modified lipocortin-I cDNA transcript as an internal standard. The lipocortin-I mRNA was decreased by 56 +/- 14% in lung tissue of ADX rats. This down-regulation of lipocortin-I mRNA was not due to a nonspecific effect of ADX, since the mRNA levels of other proteins (c-fos, c-myc, c-erbA beta, and metallothionein-II) remained unchanged. The decrease in lipocortin-I mRNA in ADX rats was reflected by a corresponding decrease in tissue (lung, spleen, liver, and kidney) lipocortin-I protein content, as assessed by quantitative Western blot analysis. Thus, ADX causes a decline in lipocortin-I message and protein, an observation compatible with the increased susceptibility to inflammatory reactions in glucocorticoid deficiency.
Cyclooxygenase (COX), or prostaglandin (PG) H synthase, plays a role in inflammatory diseases, but very limited data exist on the regulation of COX in vivo. We, therefore, studied the in vivo expression of COX in synovia from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), as well as joints of rats with streptococcal cell wall (SCW) and adjuvant arthritis. Extensive and intense intracellular COX immunostaining, which correlated with the extent and intensity of mononuclear cell infiltration, was observed in cells throughout RA synovia. Significantly less or equivocal staining was noted in OA and normal human synovia. Similarly, COX immunostaining was equivocal in the joints of normal and arthritis-resistant F344/N rats. In contrast, high level expression developed rapidly in euthymic female Lewis (LEW/N) rats throughout the hindlimb joints and overlying tissues including skin, preceding or paralleling clinically apparent experimental arthritis. COX was expressed in the joints of athymic LEW.rnu/rnu rats 2-4 d after injection of SCW or adjuvant but was not sustained. Physiological doses of antiinflammatory glucocorticoids, but not progesterone, suppressed both arthritis and COX expression in LEW/N rats. These observations suggest that, in vivo, (a) COX expression is upregulated in inflammatory joint diseases, (b) the level of expression is genetically controlled and is a biochemical correlate of disease severity, (c) sustained high level up-regulation is T cell dependent, and (d) expression is down-regulated by antiinflammatory glucocorticoids.
The injection of a suspension of a polyacrylamide gel (bio gel) into the dorsal subcutaneous area of mice induced an inflammatory reaction and the migration of neutrophils towards the inflamed site.
The intravenous administration of anti‐inflammatory drugs (dexamethasone, indomethacin and lysine‐acetylsalicylate) to Polyacrylamide gel‐treated mice inhibited the accumulation of neutrophils in the inflamed site.
A similar administration of a 36 K mouse lipocortin, induced a strong dose‐dependent inhibition of neutrophil accumulation in the inflamed site.
Dexamethasone and lipocortin inhibited the production of eicosanoids, prostaglandin E 2 (PGE 2 ) and leukotriene B 4 (LTB 4 ) in the inflamed site of Polyacrylamide gel‐treated mice.
Lipocortin impaired both phospholipase A 2 (PLA 2 ) activity and chemotaxis of isolated inflammatory neutrophils.
The present studies show an in vivo anti‐inflammatory effect of lipocortin similar to that of glucocorticosteroids. In agreement with recent data on the extracellular effects of various lipocortins, these results might implicate lipocortin(s) in the anti‐inflammatory effects of glucocorticosteroids.
Glucocorticoids inhibit superoxide (O2-) generation by phagocytes through a mechanism that remains unclear. We investigated this effect by using dexamethasone on guinea pig alveolar macrophages. O2- generation was induced either by the calcium ionophore A23187, a potent stimulus of phospholipase A2, or by the protein kinase C activator, phorbol myristate acetate (PMA). Dexamethasone inhibited O2- generation initiated by A23187 by 50-55%. This inhibition required: (a) more than 45 min incubation and was maximal after 2 h; (b) glucocorticoid receptor occupancy; and (c) protein synthesis. The inhibitory effect of dexamethasone could not be explained by an interaction with the respiratory burst enzyme NADPH oxidase since O2- generation was only weakly affected upon PMA stimulation. Lipocortin I, a glucocorticoid inducible and phospholipase A2 inhibitory protein, inhibited O2- generation initiated by A23187 but failed to modulate the respiratory burst activated by PMA. These results were obtained with lipocortin I purified from mouse lungs, human blood mononuclear cells, and with human recombinant lipocortin I. We propose that lipocortin I is capable of inhibiting the activation of NADPH oxidase only when membrane signal transduction involves phospholipase A2. By mimicking the effect of dexamethasone, lipocortin I may extend its potential anti-inflammatory action to the partial control of the formation of oxygen reactive species by phagocytes.
To examine the distribution of four annexins in non-inflamed rheumatoid arthritic and osteoarthritic synovial tissue.
Frozen sections were stained with monoclonal antibodies (MAb) specific for annexins-I, -II, -IV, and -VI, and for cell lineage related markers including CD68 and CD14 (macrophages), prolyl hydroxylase (fibroblasts), and CD3 (T cells).
Each of the annexins was present in synovial tissues in significant amounts in the three groups studied. Annexin-I was predominantly found within the synovial lining layer and double labelling showed it to be present predominantly in cells of the macrophage lineage. In rheumatoid specimens there was increased staining within the lining layer, perivascularly and on macrophages within the tissue stroma. Annexin-II was present in a distribution similar to that of annexin-I, but with more prominent perivascular staining. Annexins-IV and -VI were seen chiefly in association with areas of lymphocyte infiltration in rheumatoid tissue, whereas annexins-I and -II were absent from these areas. Endothelial cells stained weakly positive for annexins-I and -II, and more strongly for -IV and -VI.
This study demonstrates that annexins (particularly annexin-I, a putative mediator of the anti-inflammatory activities of glucocorticoids) are abundant in rheumatoid and non-rheumatoid synovial tissue, annexins-IV and -VI having a distribution distinct from that of -I and -II.
To determine daily production of nitric oxide (NO) measured as urinary nitrate excretion, and the effect of prednisolone in patients with rheumatoid arthritis (RA).
Twenty four hour urinary nitrate was measured by gas chromatography in 10 patients with RA, before and two to four weeks after commencement of prednisolone 0.5 mg/kg body weight, and in 18 healthy controls.
Before the start of prednisolone treatment the urinary nitrate excretion in patients with RA was 2.7-fold greater (p < 0.001) than that in healthy volunteers. After prednisolone it decreased significantly, by 28%, at which time inflammatory activity (as indicated by C reactive protein, erythrocyte sedimentation rate, joint count, and early morning stiffness) was also reduced considerably. Despite this decrease, the urinary nitrate excretion in patients with RA remained twice that in the control group (p < 0.05).
Our data suggest that the endogenous production of NO is enhanced in patients with RA. Furthermore, the results indicate that, in parallel with suppression of inflammation, this increased NO synthesis could be reduced by prednisolone treatment.
An enhanced formation of nitric oxide (NO) due to induction of a calcium-independent (inducible) NO synthase (iNOS) contributes importantly to the cardiovascular failure caused by bacterial endotoxin. Repeated challenges with small doses of endotoxin result in tolerance to both peripheral vascular failure and death caused by subsequent injection of a higher dose of endotoxin. Here we investigate whether tolerance to endotoxin is associated with a lack of induction of iNOS in vivo and whether endogenous glucocorticoids play a role in the development of endotoxin tolerance. In anesthetized rats, i.v. administration of Escherichia coli endotoxin [lipopolysaccharide (LPS); 2 mg.kg-1] resulted in a prolonged decrease in mean arterial blood pressure (MAP) and hyporeactivity to the contractile responses elicited by norepinephrine (NE; 10 nM) in aortic rings ex vivo. Hyporeactivity to NE was partially reversed by NG-nitro-L-arginine methyl ester (0.3 mM) in vitro, suggesting that an enhanced formation of NO contributes to this hyporeactivity. There was a substantial increase in the activity of iNOS in the lung 3 h after i.v. injection of LPS (0.2 +/- 0.1 to 6.6 +/- 0.6 pmol.mg-1.min-1; n = 5; P < 0.01). Rats injected i.p. with LPS (0.5 mg.kg-1) for 4 consecutive days became tolerant to an i.v. injection of LPS (2 mg.kg-1) in that both hypotension and vascular hyporeactivity to NE were significantly attenuated. Moreover, in these endotoxin-tolerant rats, the induction of iNOS by LPS in the lung was attenuated by 63% +/- 6%. Injection of LPS caused a 9-fold increase in plasma corticosterone (CCS) levels within 2 h and CCS levels remained significantly elevated 6 and 24 h after LPS. Animals rendered tolerant to endotoxin by administration of a low dose of LPS (0.5 mg.kg-1, i.p.) for 4 days still had a 6-fold increase in plasma CCS levels 24 h after the last injection of LPS. When endotoxin-tolerant rats were treated with the glucocorticoid receptor antagonist RU 486 (50 mg.kg-1, p.o. 3 h prior to LPS), there was a restoration of the effects of LPS (2 mg.kg-1, i.v.) in causing hypotension, vascular hyporeactivity to NE, and iNOS induction in the lung. However, in control rats RU 486 enhanced neither the decrease in MAP nor the induction of iNOS in response to LPS (2 mg.kg-1, i.v.). Thus, cardiovascular tolerance to endotoxin is accompanied and explained by reduced induction of iNOS in vivo due to the elevation of endogenous glucocorticoid levels.
Nitric oxide (NO.) is a multifunctional messenger molecule generated by a family of enzymes, collectively termed the nitric oxide synthases. We investigated the role of NO. in the modulation of two metal-dependent proteolytic enzymes (collagenase and stromelysin) which are activated during inflammatory and infective arthritis. The inflammatory mediators interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) and the bacterial cell wall fragment endotoxin, induced both nitric oxide synthase activity and stromelysin and collagenase activity in whole cell preparations and in conditioned media from explants of bovine and human cartilage. Both NO2- (the stable end-product of NO.) and metalloprotease activity were inhibited by competitive inhibitors of nitric oxide synthase. The NO. donor, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) also induced metalloprotease activity in a dose-dependent fashion. These data provide evidence that NO. plays a regulatory role in the activation of metal-dependent proteases in articular chondrocytes and cartilage.
Administration of Escherichia coli lipopolysaccharide (LPS; 10 mg/kg i.v.) to male Wistar rats caused within 240 min (i) a sustained fall (approximately 30 mmHg) in mean arterial blood pressure, (ii) a reduction (> 75%) in the pressor responses to norepinephrine (1 microgram/kg i.v.), and (iii) an induction of nitric oxide synthase (iNOS) as measured in the lung. Dexamethasone (1 mg/kg i.p. at 2 h prior to LPS) attenuated the hypotension and the vascular hyporeactivity to norepinephrine and reduced (by approximately 77%) the expression of iNOS in the lung. These effects of dexamethasone were prevented by pretreatment of LPS-treated rats with a neutralizing antiserum to lipocortin 1 (anti-LC1; 60 mg/kg s.c. at 24 h prior to LPS) but not by a control nonimmune sheep serum. Stimulation of J774.2 macrophages with LPS (1 microgram/ml for 24 h) caused the expression of iNOS and cyclooxygenase 2 (COX-2) protein and significantly increased nitrite generation; this was prevented by dexamethasone (0.1 microM at 1 h prior to LPS), which also increased cell surface lipocortin 1. Pretreatment of J774.2 cells with anti-LC1 (1:60 dilution at 4 h prior to LPS) also abolished the inhibitory effect of dexamethasone on iNOS expression and nitrite accumulation but not that on COX-2 expression. A lipocortin 1 fragment (residues 1-188 of human lipocortin 1; 20 micrograms/ml at 1 h prior to LPS) also blocked iNOS in J774.2 macrophages activated by LPS (approximately 78% inhibition), and this too was prevented by anti-LC1. We conclude that the extracellular release of endogenous lipocortin 1 (i) mediates the inhibition by dexamethasone of the expression of iNOS, but not of COX-2, and (ii) contributes substantially to the beneficial actions of dexamethasone in rats with endotoxic shock.
Nitric oxide (NO) is important in many biological functions. It is generated from L-arginine by the enzyme NO synthase (NOS). The cytokine-inducible NOS (iNOS) is activated by several immunological stimuli, leading to the production of large quantities of NO which can be cytotoxic. To define the biological role of iNOS further, we generated iNOS mutant mice. These are viable, fertile and without evident histopathological abnormalities. However, in contrast to wild-type and heterozygous mice, which are highly resistant to the protozoa parasite Leishmania major infection, mutant mice are uniformly susceptible. The infected mutant mice developed a significantly stronger Th1 type of immune response than the wild-type or heterozygous mice. The mutant mice showed reduced nonspecific inflammatory response to carrageenin, and were resistant to lipopolysaccharide-induced mortality.
Recent evidence suggests that the production of nitric oxide (NO) may have important roles in the regulation of osteoblast and osteoclast metabolism. The present study was performed to investigate the effects of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) on the expression of inducible NO-synthase (iNOS) and to measure high-output production of NO by primary rat osteoblasts and osteoblastic cell lines ROS 17/2.8, MC3T3-E1 and MG-63. In addition, we have investigated if NO may mediate some of the effects of these cytokines on osteoblast metabolism. Northern blots and immunocytochemistry revealed time-dependent iNOS messenger RNA and protein expression in primary rat osteoblasts in response to cytokine treatment. Reverse transcription polymerase chain reaction amplified an 807-base pair (bp) product from ROS 17/2.8 cells, which had a size and restriction enzyme-cut pattern identical to that predicted for authentic rat iNOS. Nitrite accumulation in culture medium was induced by IFN-gamma in a time- and dose-dependent manner and inhibited by cotreatment with inhibitors of NOS activity and by dexamethasone. IL-1 beta, TNF-alpha, and bacterial lipopolysaccharide were found to have weak stimulatory effects on nitrite production on their own. However, IL-1 beta and TNF-alpha showed strong synergy with IFN-gamma, but, surprisingly, lipopolysaccharide was found to exert potent inhibitory effects on IFN-gamma-induced nitrite synthesis. Basal production of nitrite and induction of its synthesis was similarly observed with primary rat osteoblasts as well as ROS 17/2.8, MC3T3-E1, and MG-63 cell lines. Cytokine-induced NO production significantly reduced osteoblast activity, as was evidenced by inhibition of DNA synthesis, cell proliferation, alkaline phosphatase activity, and osteocalcin production. The results provide evidence for a basal expression of iNOS activity and show that the iNOS messenger RNA, protein, and enzyme activity are all induced by cytokines across the species. The data further suggest that osteoblast-derived NO may have an important role in mediation of localized bone destruction associated with inflammatory bone diseases such as rheumatoid arthritis.
Large multilamellar liposomes containing dichloro-methylene-bisphosphonate (clodronate; Clo), a bisphosphonate that becomes toxic when intracellularly concentrated, were used to therapeutically target macrophages (M phi) in rats with established adjuvant arthritis (AA; i.v. on days 10,11,12) or antigen-induced arthritis (AIA; i.v. or i.a. on 3 h, days 1,2). In established AA, i.v. injection of Clo-liposomes led to significant, long-lasting amelioration of clinical parameters, and to reduced destruction of the ankle joint even several weeks after termination of treatment. In the acute phase of established AIA, intravenous treatment induced transient clinical amelioration, but did not counteract joint destruction. I.a. treatment in AIA was ineffective. Systemic treatment with anti-M phi principles induces amelioration of both AA and AIA; the improvement appears more profound in AA, i.e., the model with a more systemic character. Preliminary data indicate that depletion of M phi occurs in the liver rather than in spleen, draining lymph nodes or synovial membrane. In addition, local treatment with the same principle is ineffective in AIA. Therefore, systemic elimination of M phi in different sites may be crucial for effective therapy of arthritis with anti-M phi agents.
Oral glucocorticoids are widely used to treat patients with rheumatoid arthritis, but their effect on joint destruction, as assessed radiologically, is uncertain.
We conducted a randomized, double-blind trial comparing oral prednisolone (7.5 mg daily for two years) with placebo in 128 adults with active rheumatoid arthritis of less than two years' duration. Except for systemic corticosteroids, other treatments could be prescribed. The primary outcome variables were the progression of damage as seen on radiographs of the hand after one and two years, as measured by the Larsen index, and the appearance of erosions in hands that had no erosions at base line. The radiographs were viewed jointly by a radiologist and a rheumatologist who were unaware of the treatment assignment and the time point at which the films were obtained.
The statistical analysis of radiologically detected changes was based on 106 patients for whom there were films obtained at base line and two years later. After two years, the Larsen scores increased by a mean of 0.72 unit in the prednisolone group, indicating very little change, and by 5.37 units in the placebo group, indicating substantial joint destruction (P = 0.004). Of the 212 hands of these patients, 147 (69.3 percent) had no erosions at the start of the study. At two years, 15 of the 68 such hands in the prednisolone group (22.1 percent) and 36 of the 79 such hands in the placebo group (45.6 percent) had acquired erosions (difference, 23.5 percentage points; 95 percent confidence interval, 5.9 to 40.7; P = 0.007). The patients in the prednisolone group had greater reductions than the patients in the placebo group in scores on an articular index and for pain and disability at 3 months; for pain at 6 months; and for disability at 6, 12, and 15 months (all P < 0.05). There was no difference between groups in standardized scores for the acute-phase response. The adverse events were typical of those encountered with antirheumatoid drugs.
In patients with early, active rheumatoid arthritis, prednisolone (7.5 mg daily) given for two years in addition to other treatments substantially reduced the rate of radiologically detected progression of disease.
Reaction of nitric oxide (NO.) with superoxide radical generates peroxy-nitrite, which can decompose to products that nitrate aromatic amino acids. Such nitro-aromatics may be 'markers' of NO.-dependent oxidative damage. Blood serum and synovial fluid from patients with the inflammatory joint disease rheumatoid arthritis contain 3-nitrotyrosine. By contrast, body fluids from normal subjects and patients with osteoarthritis contain no detectable 3-nitrotyrosine; much lower levels were found in serum from patients in the early stages of rheumatoid arthritis. This is evidence that NO. plays a role in joint damage in rheumatoid arthritis.
We have investigated the ability of cells derived from the human joint to generate nitric oxide (NO). Synovial fibroblasts, articular chondrocytes and osteoblasts were cultured from tissues of patients undergoing hip replacement surgery, and synovial fluid leucocytes were obtained from patients undergoing joint aspiration. There was little spontaneous generation of NO by any of the cells after culture, but synovial fibroblasts, articular chondrocytes and osteoblasts all produced large quantities of NO in response to a cytokine mix of interleukin (IL)-1 beta + tumour necrosis factor alpha (TNF alpha) + interferon (IFN gamma). Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed the presence of mRNA transcripts for the inducible isoform of NO synthase in cytokine-stimulated but not in unstimulated cells. In contrast, leucocytes from synovial fluid did not produce NO either spontaneously or after cytokine stimulation, and mRNA for inducible NO synthase (iNOS) was not detected in these cells even by nested PCR. There were significant differences in the regulation of NO production between chondrocytes and other cells. Only chondrocytes generated NO in response to IL-1 beta or TNF alpha alone, whereas synovial fibroblasts and osteoblasts required the presence of at least two cytokines to generate NO. Dexamethasone (10(-6)M) had a small but significant inhibitory effect on NO production by chondrocytes, synovial fibroblasts and osteoblasts. Our results indicate that several cells within the human joint have the potential to generate NO in the presence of an appropriate pro-inflammatory cytokine stimulus, while leucocytes in synovial fluid are not a significant source of NO. The data support suggestions that NO is produced within the inflamed joint in diseases such as rheumatoid arthritis.
Recombinant human annexin I and a monoclonal antibody specific for this protein (mAb 1B) were used to investigate surface binding of this member of the annexin family of proteins to peripheral blood monocytes. Flow cytometric analysis demonstrated trypsin-sensitive, saturable binding of annexin I to human peripheral blood monocytes but not to admixed lymphocytes. A monoclonal antibody that blocks the anti-phospholipase activity of annexin I also blocked its binding to monocytes. These findings suggest the presence of specific binding sites on monocytes. Furthermore, surface iodination, immunoprecipitation and SDS/PAGE analysis were used to identify two annexin I-binding proteins on the surface of monocytes with molecular masses of 15 kDa and 18 kDa respectively. The identification and characterization of these annexin I-binding molecules should help us to better understand the specific interactions of annexin I with monocytes that lead to down-regulation of pro-inflammatory cell functions.
The mechanisms that regulate inflammatory responses, and their dysfunction in chronic inflammatory diseases, are poorly understood. Lipocortin 1 is a potential mediator of the anti-inflammatory effects of glucocorticoid hormones. Following the discovery of putative receptors on phagocytes for lipocortin 1, Nick Goulding and Paul Guyre here offer one explanation for the self-limitation of inflammation and the impairment of the mechanism in chronic inflammatory disease.
Autoantibodies to the antiinflammatory protein lipocortin-1 have been found in patients with rheumatoid arthritis (RA) receiving oral glucocorticoids. The highest antibody titers correlated with a requirement for high maintenance doses of steroid (> 7.5 mg/day prednisolone). Forty-two patients with RA were grouped according to high or low autoantibody titer. In 18 patients, peripheral blood leukocyte counts and phenotypic analysis were performed before and 4 h after a single intravenous (iv) dose of 100 mg hydrocortisone. The group with low titer antibody exhibited a normal poststeroid peripheral blood lymphopenia, but the response in the group with high antibody titer was considerably blunted. In a 2nd study, 24 patients received 3 separate doses of 1000 mg iv methylprednisolone. After 8 weeks the group with the high titer antibody had shown no improvements in clinical or laboratory variables observed in the group with low titer antibody. Thus, the presence of high titer antilipocortin-1 antibody is associated with impaired responses to glucocorticoid therapy both in terms of clinical efficacy and effects on the immune system. This could explain the relative glucocorticoid resistance reported in a proportion of patients with RA.
After activation with IFN-gamma, thioglycollate-elicited murine peritoneal macrophages kill schistosomula of Schistosoma mansoni in vitro by an L-arginine-dependent mechanism which involves the production of reactive nitrogen oxides (NO). In the present study we demonstrate that the regulatory cytokines IL-10, IL-4, and transforming growth factor-beta (TGF-beta) are potent inhibitors of this extracellular killing function of activated macrophages. Each cytokine was found to suppress killing of schistosomula in a dose-dependent fashion. The activity of IL-10 was not permanent, because subsequent treatment with additional IFN-gamma 2 to 6 h later reversed the inhibition of macrophage larval killing. More importantly, the combination of suboptimal levels of any two of these three cytokines was found to give a potent synergistic suppression of schistosomulum killing by IFN-gamma-treated macrophages. Similarly, IL-10, IL-4, or TGF-beta alone blocked the production of NO, and when used in combination these cytokines exhibited an enhanced inhibitory effect on nitrite production. Macrophage-mediated killing of schistosomula through the generation of NO has been shown previously to be a major effector mechanism of schistosome immunity. The results presented here suggest that the suppression of this mechanism by induction of the regulatory cytokines IL-10, IL-4, and TGF-beta, which are known to be produced during schistosome infection, may be an important strategy used by the parasite to evade macrophage-mediated immune destruction.
We have developed two monoclonal antibodies to human lipocortin-1 (103 and 105) as reagents for quantitating the protein in biological systems and neutralizing its activity. Lipo 105 is a high affinity antibody that is functional in ELISA and Western blot formats. The antibody recognizes a site between amino acids 30 and 55 in the lipocortin-1 sequence and can be used on native or denatured protein. Lipo 103 is an antibody that neutralizes the phospholipase A2 inhibitory activity of lipocortin-1 by blocking binding of the protein to phospholipid surfaces. The antibody is specific for native human lipocortin-1. Lipo 103 was recently shown to block lipocortin-1-dependent differentiation of a squamous carcinoma cell line, demonstrating its usefulness as a probe for function.
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Using immunoaffinity-purified polyclonal anti-human recombinant tumor necrosis factor alpha (TNF alpha) F(ab')2 fragments and immunohistochemical techniques, the cells that make TNF alpha were localized in the inflamed synovial tissue of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Anti-TNF alpha antibody-stained cells were demonstrated in 9 of 11 RA and 2 of 4 OA but none of 5 normal synovial membranes examined. In RA, 26-64% of the lining layer cells were positive for TNF alpha. In the interaggregate area, 10-30% of the cells contained TNF alpha, often in a perivascular distribution, and up to 19% of the cells in lymphoid aggregates stained for TNF alpha. Some endothelial cells also stained with these antibodies. In OA tissues, the TNF alpha-containing cells were found predominantly in the deeper layer. Cells containing TNF alpha were also found at the cartilage-pannus junction in all 4 RA specimens examined. Double immunofluorescence analysis demonstrated that most TNF alpha-secreting cells in the RA synovial membrane expressed the monocyte/macrophage marker antigens CD11b and CD14, and a few expressed the T cell marker CD3. Our findings provide histologic evidence that TNF alpha is locally produced in the lining and deeper layers of the synovium by cells of the monocyte/macrophage lineage, supporting its role in inflammation. Further, our findings demonstrate that TNF alpha is produced by cells at the cartilage-pannus junction, which could affect chondrocyte metabolism, leading to the cartilage degradation in RA.
The presence and amount of the anti-inflammatory protein lipocortin 1 was determined in plasma and peripheral blood leucocytes by a highly specific, enzyme-linked immunosorbent assay. Within 120 min of a single intravenous dose of 100 mg hydrocortisone, the intracellular concentrations of lipocortin 1 in peripheral monocytes in 7 of 8 healthy men increased by a median of 225% (range 129-507%) compared with pretreatment levels, and mononuclear cell-surface lipocortin increased by a median of 224% (range 76-483%). Placebo injections had no effect. There was no increase at any time in free plasma or polymorph-associated lipocortin. In 3 of 4 subjects, induction of lipocortin was also observed when whole unseparated blood was incubated in vitro after steroid administration, but cells which had first been isolated and purified were refractory to such induction. Thus rapid changes in the concentration of an active anti-inflammatory protein can occur in man after normal therapeutic doses of hydrocortisone.
Granulocyte-macrophage CSF (GM-CSF) is a potent stimulator of macrophages and neutrophils and is produced by rheumatoid arthritis (RA) synovium. We now report studies that identify some of the synovial cells and cytokines responsible for local GM-CSF production and gene expression in RA. GM-CSF was assayed by ELISA in supernatants from cultured RA fibroblast-like synoviocytes stimulated with various cytokines (IL-1 beta, TNF-alpha, macrophage-CSF, IFN-gamma, IL-6, and TGF-beta). Immunoreactive GM-CSF was detected in IL-1 beta and TNF-alpha-stimulated cultures, but not in cells cultured in medium or stimulated with any of the other cytokines. IL-1 and TNF-alpha had a synergistic effect on GM-CSF production. GM-CSF gene expression by fibroblast-like synoviocytes was analyzed by ribonuclease protection assay, Northern blot analysis, and in situ hybridization. Both IL-1 beta and TNF-alpha induced GM-CSF mRNA accumulation, with a maximum effect after 4 h of stimulation. We then studied GM-CSF production by macrophage-like synoviocytes (MLS) isolated from fresh synovial specimens by flow microfluorimetry. Fresh MLS spontaneously secreted the cytokine and exogenous IL-1 beta or TNF-alpha had no effect. After 1 wk in culture, additional stimulation with IL-1 beta or TNF-alpha was required for GM-CSF production. Finally, in situ hybridization performed on freshly isolated subpopulations of synovial cells, identified GM-CSF RNA transcripts in MLS.
Lipocortins form a group of proteins that have been proposed as mediators of the anti-inflammatory actions of glucocorticoids. Intracerebroventricular injection of a recombinant fragment of lipocortin 1 (NH2-terminal 1-188) caused dose-dependent (0.4-1.2 micrograms) reductions in the acute increases in colonic temperature and oxygen consumption, which occurred in response to central injections of recombinant interleukin 1 beta and gamma-interferon in conscious rats. In contrast the lipocortin fragment did not affect the response to prostaglandin E2, and its activity was prevented by heat treatment or by pretreatment of animals with polyclonal antiserum raised to the fragment. Central injection of antiserum significantly enhanced the thermogenic responses to interleukin 1 beta in rats treated with dexamethasone without affecting the responses in normal animals. These results support a physiological role for lipocortin in the central effects of glucocorticoids.
If the load on a tetanized fiber is abruptly changed to a new steady value, the ensuing fiber length change shows the well-known "isotonic velocity transient," in which the velocity oscillates before settling at some steady value. We studied sarcomere dynamics during these transients using two methods: optical diffraction and a segment-length method. Our principal aim was to determine whether these transients might be a reflection of the fact that sarcomere shortening is often found to be stepwise. We found that pauses in sarcomere shortening occurred during the low-velocity phases of the transient and that steps of sarcomere shortening occurred during the high-velocity phases. Thus the isotonic transient appears to arise from the steps. In addition to the isotonic transient, we studied the well-known isometric transient, in which fiber length is abruptly changed, and ensuing tension response is measured. Again, we found that the transient may be a reflection of the stepwise shortening pattern.
Human recombinant lipocortin 1 has been tested for anti-inflammatory activity in a conventional model of acute inflammation. Microgram amounts of the protein, locally administered, inhibited edema of the rat paw when induced by subplantar injections of carrageenin: the ED50 was 10-20 micrograms per paw, and inhibition (maximum of 60-70%) was not dependent upon an intact adrenal cortex. Doses of lipocortin that produced approximately 50% inhibition in the carrageenin test were inactive against edema elicited by bradykinin, serotonin, platelet-activating factor-acether, or dextran, whereas edema caused by Naja mocambique venom phospholipase A2 was strongly inhibited by lipocortin. The protein inhibited edema when rats were pretreated with agents that depleted mast-cell amines, kininogen, or polymorphonuclear leukocytes prior to initiation of the carrageenin edema but had no inhibitory action when rats were pretreated with the dual cyclooxygenase/lipoxygenase inhibitor BW 755C. These results demonstrate that human recombinant lipocortin has potent local anti-inflammatory activity, probably through selectively interfering with eicosanoid generation. Lipocortin is relatively ineffective against edema caused by mast-cell degranulation or kinins, except when degranulation is caused by phospholipase A2.
A complex pattern of interactions appears to exist between the immune and neuroendocrine systems. Recently, vasopressin, oxytocin and vasoactive intestinal peptide have been isolated from the thymus. Using a rat somatostatin antisense RNA probe we have demonstrated expression of the somatostatin gene in the rat thymus. Furthermore, we have shown that the levels of thymic somatostatin mRNA exhibit a bell-shaped response to dexamethasone administration. Lipocortin I and II antisense RNA probes have been used as a positive control for the effects of the dexamethasone. We would suggest that somatostatin acts in the thymus in a paracrine mode to modulate T lymphocyte development.
Slices of rabbit articular cartilage synthesized large quantities of nitric oxide (NO) following exposure to human recombinant interleukin-1 beta (hrIL-1 beta) or rabbit synovial cytokines (CAF). Each of these stimuli also strongly suppressed the biosynthetic incorporation of 35SO4(2-) into the glycosaminoglycans (GAGs) of cartilage proteoglycans. Treatment of cartilage fragments with L-NG-monomethylarginine (L-NMA), a competitive inhibitor of NO synthase, both inhibited NO synthesis in response to IL-1 and CAF and restored proteoglycan synthesis. D-NMA was inactive in this regard, and L-arginine reversed the effects of L-NMA. S-nitrosylacetylpenicillamine (SNAP), an organic donor of NO, reversibly mimicked the effect of IL-1 and CAF on 35SO4(2-) incorporation. These data suggest that endogenously synthesized NO is the mediator which reduces cartilage proteoglycan synthesis in response to cytokines such as IL-1 and CAF. Antagonists of NO production may promote cartilage matrix synthesis and thus have potential as chondroprotective or chondroreparative agents.
Nitric oxide (NO) is a short-lived free radical that plays an important regulatory role in several biological processes. Cytokines such as interleukin-1, tumor necrosis factor, and interferon-gamma have been shown to stimulate NO production in many cells types. Although these cytokines are known to have potent effects on bone remodeling and osteoblast function, the role of NO as an effector molecule in bone has been little studied. Here we investigate the effects of cytokines and calciotropic hormones on NO production by human osteoblast-like cells (hOB) and the role of NO as a modulator of osteoblast growth. Unstimulated hOB produced little NO, as reflected by measurement of nitrite concentrations in hOB-conditioned medium. NO production was not significantly altered by PTH and 1,25-dihydroxyvitamin D or human recombinant interleukin-1 beta (10 U/ml), tumor necrosis factor-alpha (25 ng/ml), and interferon-gamma (100 U/ml) individually. Combinations of all three cytokines at these concentrations, however, dramatically increased both NO generation and cGMP production. The stimulatory effect of cytokines on NO production began 12 h after exposure and was inhibited by cycloheximide, actinomycin-D, dexamethasone, and the competitive inhibitor of NO synthase L-NG-monomethylarginine. Reverse transcription/polymerase chain reaction analysis of hOB RNA, followed by direct sequencing of the amplified products, showed that hOB express the inducible, rather than the endothelial or neuronal, forms of NO synthase. Cytokine-induced increases in NO production were associated with a marked inhibition of [3H]thymidine uptake to less than 10% of that observed in control cultures. Abrogation of NO synthesis with L-NG-monomethylarginine under these conditions significantly increased [3H]thymidine uptake to approximately 20% of the control value, suggesting that NO may partly be responsible for the inhibition of osteoblast proliferation induced by these cytokines. Our data indicate that proinflammatory cytokines induce NO production in osteoblast-like cells and show and that this mediator plays a role in regulating cell growth. These findings may have important implications for the pathogenesis and management of bone loss in diseases associated with cytokine activation, such as rheumatoid arthritis.
In this study, we have identified the source of nitric oxide (NO) produced in the human inflammatory joints by analyzing expression of inducible NO synthase. In ex vivo organ cultures, both inflammatory synovium and cartilage from patients with rheumatoid arthritis produced NO. The NO production was suppressed by NG-monomethyl-L-arginine, an inhibitor of NO synthase. The amount of NO produced by the synovium correlated with the proportion of CD14+ cells in the corresponding tissue (r = 0.8, P < 0.05). Immunohistochemical analysis as well as in situ hybridization showed that inducible NO synthase was predominantly expressed in synovial lining cells, endothelial cells, chondrocytes, and to a lesser extent, in infiltrating mononuclear cells and synovial fibroblasts. The synovial lining cells and the infiltrating cells expressing inducible NO synthase were identified where CD14+ cells were located. Together with morphological features, this suggests that they are type A synoviocytes. NO production from freshly isolated synoviocytes and chondrocytes was up-regulated by in vitro stimulation with a combination of IL-TNF-beta, TNF-alpha, and LPS. In summary, the present results suggest that NO is produced primarily by CD14+ synoviocytes, chondrocytes, and endothelial cells in inflammatory joints of arthritides. NO production can be upregulated by cytokines present in inflamed joints. The increased NO production may thus contribute to the pathological features in inflammatory arthritides.
Lipocortin 1, a putative mediator of the anti-inflammatory actions of glucocorticoids, is present intracellularly in a variety of tissues including human peripheral blood leukocytes. We investigated the presence of lipocortin 1 in human leukocyte subsets using permeabilization flow cytometry. Constitutive lipocortin 1 was detected in U937 myelomonocytic leukemia cells, and lipocortin 1 was increased by treatment with PMA or PMA+IFN-gamma (P < 0.05) but not by dexamethasone. Lipocortin 1 was present in all leukocyte subsets except B lymphocytes (CD19/20+, P < 0.001). Lipocortin 1 content was maximal in monocytes and polymorphonuclear neutrophils and least in lymphocytes (P < 0.001). Monocyte lipocortin 1 was strongly associated with surface expression of CD14 and HLA-DR. Among non-B lymphocytes, a range of lipocortin 1 fluorescence was observed. Lipocortin 1 fluorescence was greatest in natural killer cells (CD56+, P < 0.001) and CD57+ cells, but T cell subset markers did not otherwise discriminate variations in lipocortin 1. Induction of lymphocyte proliferation by PHA, anti-CD3, Con A, superantigen, and SAC was not associated with significant shifts in lipocortin 1 content. Dexamethasone (10(-10)-10(-6) M) did not induce increases in PB leukocyte lipocortin 1. We conclude that lipocortin 1 content in human leukocytes varies significantly among phenotypic subsets. This has significance for the investigation of inflammatory disease where certain cell types predominate.
The contribution of reactive oxygen species (ROS), in particular hydroxyl radical (OH.), to joint inflammation was examined in rats developing adjuvant arthritis (AA) by treatment with ROS scavengers dimethylthiourea (DMTU) and DMSO. Adjuvant arthritis was induced in Sprague-Dawley (SD) rats by a single intradermal (i.d.) injection of Mycobacterium tuberculosis (MT) in oil on day 0. By day 14, all rats exhibited arthritis in the hindlimbs and the majority had involvement of the forelimbs. A marked inflammatory cell influx (75% neutrophils) was present in the synovial fluid. These cells, in vitro, spontaneously produced OH. (0.96 +/- 0.28 OH. units/h per 10(5) cells). In contrast, spontaneous OH. production by normal circulating leucocytes was absent (0.07 +/- 0.03 OH. units/h per 10(5) cells). Adjuvant-injected rats were treated with DMTU (500, 250 and 100 mg/kg), DMSO (330 and 165 mg/kg) or saline (disease control) once daily on days 8, 9 and 10 and twice daily on days 11, 12 and 13 postadjuvant injection. Both DMTU and DMSO significantly reduced the clinical evidence of arthritis (clinical scores: DMTU [500 mg/kg] = 0, P < 0.0001; DMSO [3.0 mL/kg] = 0.4 +/- 0.3, P < 0.01, compared with disease control = 2.3 +/- 0.3). Synovial fluid cell accumulation was also significantly reduced (DMTU [500 mg+kg] = 0.5 +/- 0.1 x 10(5) cells/four joints, P < 0.0001; DMSO [3.0 mL/kg] 2.75 +/- 1.9 x 10(5) cells/four joints, P < 0.01 compared with disease control = 11.76 +/- 1.7 x 10(5) cells/four joints). Neither treatment inhibited cutaneous delayed type hypersensitivity (DTH) to the disease inducing antigen.(ABSTRACT TRUNCATED AT 250 WORDS)
To determine whether rabbit synovial fibroblasts can synthesize nitric oxide (NO) and, if so, how production is regulated by cytokines.
Primary cultures of synovial fibroblasts (type B synoviocytes) were established from synovia excised from the knee joints of New Zealand white rabbits. Synthesis of NO was measured as nitrite accumulation in conditioned media in the presence or absence of various cytokines and other activators.
Resting cultures of synoviocytes normally produced little or no NO. However, production of this free radical was induced by interleukin 1 (IL-1), tumor necrosis factor alpha (TNF-alpha) or the phagocytosis of latex beads; in some cultures, the synthesis of NO occurred spontaneously. In each case, NO synthesis began approximately 9 h after the addition of cytokines, suggesting the involvement of an inducible form of NO synthase. Antagonists of this phenomenon included interferon gamma (IFN-gamma), which weakly inhibited NO production, and transforming growth factor beta (TGF-beta), a very strong inhibitor. Platelet derived growth factor (PDGF) inhibited NO synthesis by cells stimulated with IL-1, but not by cells stimulated with TNF-alpha. Synovial autocrine factors (CAF) modestly induced NO synthesis, but inhibited synthesis by IL-1; TGF-beta was identified as an inhibitory component of CAF. Phorbol myristate acetate (PMA) had only a small inductive effect, and inhibited induction by IL-1. However, the protein kinase inhibitor staurosporin was a strong inducer. Modulators of cyclic nucleotides, in contrast, had relatively modest effects on NO synthesis. Inhibition of NO biosynthesis by NG-monomethyl-L-arginine (NMA) had no effect upon the increase in the production of prostaglandin E2 (PGE2), matrix metalloproteinases (MMP) or lactate by synoviocytes responding to IL-1. The rabbit synoviocyte cell line, HIG-82, did not synthesize detectable NO under any of the culture conditions tested.
Synoviocytes are a potential source of NO in arthritic joints.
Parenchymal cells were isolated from the liver of male calves, and monolayer cultures formed were treated with glucocorticoids to examine whether haptoglobin, appearance of which is associated with hepatic lipidosis (fatty liver) in cattle, is induced by steroid hormones. Without addition of dexamethasone, only trace amounts of haptoglobin were detected in culture medium. With addition of dexamethasone (10(-12) to 10(-4) M), considerable amounts of haptoglobin were released into the medium. Maximal release was observed at concentrations of 10(-8) to 10(-6) M dexamethasone. Haptoglobin release was similarly induced by cortisol, although the effect was less potent than that of dexamethasone. Actinomycin D (a known protein synthesis inhibitor) dose-dependently reduced amounts of haptoglobin released in response to 10(-8) M dexamethasone. Dexamethasone also induced annexin I, which is known to be synthesized in response to glucocorticoids. Dexamethasone treatment resulted in reduced protein kinase C activity in the cell cytosol, which has been shown to be an early event in dexamethasone-treated cells. Other than glucocorticoids, estradiol induced haptoglobin release, whereas progesterone was less effective. The association of haptoglobin with hepatic lipidosis can be reasonably explained by the fact that haptoglobin production by the liver is induced by glucocorticoids and estradiol, and these steroid hormones are triggers for development of hepatic lipidosis in cattle.
A549 cells grown under serum free conditions do not express cyclooxygenase 2 (cox 2). However, addition of IL-1 beta results in the induction of cox 2 in a time and dose dependent manner; actinomycin D completely blocks this induction. Dexamethasone completely suppressed the induction of cox 2 only if present during the first 3.5h of IL-1 beta treatment but not if added after 3.5h. Treatment with a neutralising monoclonal antibody (1A, Biogen) specific to lipocortin-1 failed to reverse this inhibition by dexamethasone. However, using this same antibody we were able to reverse completely the effects of dexamethasone on the suppression of PGE2 release. These observations support the idea that glucocorticoids directly regulate cox 2 expression at the transcriptional level and this phenomenon is not mediated by lipocortin-1.
To investigate leukocyte lipocortin-1 production in rheumatoid arthritis (RA).
Eight control and 8 RA subjects received 100 mg hydrocortisone intravenously. Leukocyte lipocortin-1 was measured by enzyme-linked immunosorbent assay.
Hydrocortisone induced significant increases in lipocortin-1 production by control mononuclear cells (MNC) (P = 0.006 versus baseline) but not by RA MNC (P = 0.44 versus baseline). Peak lipocortin-1 levels in control MNC were significantly higher than those in RA MNC (P = 0.014).
These results indicate that glucocorticoid-induced MNC lipocortin-1 production is impaired in RA.
Annexin-I is a calcium dependent phospholipid binding and phospholipase A2 (PLA2) inhibitory protein. A 'substrate depletion' model has been proposed for the mechanism of PLA2 inhibition by annexin-I in studies with 14 to 18 kDa PLA2s. Herein, we have studied the inhibition mechanism using 100 kDa cytosolic PLA2 from porcine spleen. The inhibition has been measured at various substrate and calcium ion concentrations. The pattern of PLA2 inhibition by annexin-I was consistent with a 'specific interaction' mechanism rather than the 'substrate depletion' model. Apparent contraction with previous studies can be explained by the calcium-dependent binding of annexin-I to the substrate.
To determine whether rat osteoblasts synthesize proteins of the annexin family and to evaluate the extent to which glucocorticoids modulate the expression of annexins by these cells, osteoblasts were grown in primary cultures in the absence or presence of dexamethasone, and the expression of annexins was evaluated by immunoblotting using polyclonal antibodies against human annexins. Four different annexins (I, II, V, and VI) were found to be expressed by rat osteoblasts. The expression of annexin I, but not the other annexins studied, was increased in osteoblasts cultured in the presence of dexamethasone (173 +/- 33% increase comparing untreated cells and cells treated for 10 days with 5 x 10(-7) M dexamethasone). Increased expression of annexin I was observed after the third day of exposure to dexamethasone and rose thereafter until day 10; annexin I expression increased with dexamethasone concentrations above 10(-10) M throughout the range of concentrations studied. The increase in annexin I protein was associated with an increase in annexin I mRNA and was completely blocked by the concomitant addition of the glucocorticoid receptor antagonist RU 38486. The increase in annexin I content following dexamethasone treatment was associated with an increase in alkaline phosphatase activity and PTH-induced cAMP stimulation, whereas phospholipase A2 activity in the culture medium was reduced to undetectable levels. The finding that four annexins are expressed in rat osteoblasts in primary culture raises the possibility that these proteins could play an important role in bone formation by virtue of their ability to bind calcium and phospholipids, serve as Ca2+ channels, interact with cytoskeletal elements, and/or regulate phospholipase A2 activity. In addition, the dexamethasone-induced increase in annexin I may represent a mechanism by which glucocorticoids modify osteoblast function.
IL-1 is a pro-inflammatory cytokine which controls many features of the immune and inflammatory response. When injected into a mouse 6-day-old air-pouch, human rIL-1 (1 to 100 ng) induced in a dose-dependent fashion a migration of PMN that could be reliably assessed 4 h after injection. Both IL-1 alpha and IL-1 beta were active in this model. The effect of the cytokine was inhibited by local administration of actinomycin D (1 to 10 micrograms), alpha-melanocyte-stimulating hormone (200 micrograms), and a mAb recognizing IL-1R type I (10 micrograms). Indomethacin (1 mg/kg), an inhibitor of cyclo-oxygenase, and BW4AC (2 mg/kg), a selective lipoxygenase inhibitor, were without effect but moderate inhibition was seen with the platelet-activating factor antagonist WEB2086 (1 to 10 mg/kg). The glucocorticoid dexamethasone (0.015 to 1.5 mg/kg) potently inhibited the elicitation of neutrophils induced by IL-1 when given systemically 2 h before the cytokine. The steroid-induced anti-inflammatory protein lipocortin 1 (LC1) also produced a dose-dependent inhibition of PMN migration into the pouch with an ED50 of approximately 0.15 to 0.21 mg/kg. The denatured protein was without effect. Passive immunization of mice with a polyclonal sheep antiserum or a mAb raised against LC1 abolished the inhibitory action of dexamethasone whereas preimmune serum or control IgG were without significant effect. These findings provide further evidence that LC1 is involved in the anti-inflammatory action of glucocorticosteroids and suggest that this protein may act as an endogenous regulator of IL-1 action.
Glucocorticoids are immunosuppressive and antiinflammatory agents that act through multiple mechanisms. This review highlights recent evidence that lipocortin-1, a member of the annexin family of calcium-binding proteins, can be induced by glucocorticoids, and may mediate some of the effects of glucocorticoids through putative lipocortin-1 receptors, which have been found on the surface of phagocytic cells. Recent advances in annexin biology have been drawn together to formulate a novel hypothesis for the regulation of inflammation.
1. An immuno-neutralization strategy was employed to investigate the role of endogenous lipocortin 1 (LC1) in acute inflammation in the mouse. 2. Mice were treated subcutaneously with phosphate-buffered solution (PBS), non-immune sheep serum (NSS) or with one of two sheep antisera raised against LC1 (LCS3), or its N-terminal peptide (LCPS1), three times over a period of seven days. Twenty four hours after the last injection several parameters of acute inflammation were measured including zymosan-induced inflammation in 6-day-old air-pouches, zymosan-activated serum (ZAS)-induced oedema in the skin, platelet-activating factor (PAF)-induced neutrophilia and interleukin-1 beta (IL-1 beta)-induced corticosterone (CCS) release. 3. At the 4 h time-point of the zymosan inflamed air-pouch model, treatment with LCS3 did not modify the number of polymorphonuclear leucocytes (PMN) recruited: 7.84 +/- 1.01 and 7.00 +/- 0.77 x 10(6) PMN per mouse for NSS- and LCS3 group, n = 7. However, several other parameters of cell activation including myeloperoxidase (MPO) and elastase activities were increased (2.2 fold, P < 0.05, and 6.5 fold, P < 0.05, respectively) in the lavage fluids of these mice. Similarly, a significant increase in the amount of immunoreactive prostaglandin E2 (PGE2; 1.81 fold, P < 0.05) and IL-1 alpha (2.75 fold, P < 0.05), but not tumour necrosis factor-alpha (TNF-alpha), was also observed in LCS3-treated mice. 4. The recruitment of PMN into the zymosan inflamed air-pouches by 24 h had declined substantially (4.13 +/- 0.61 x 10(6) PMN per mouse, n = 12) in the NSS-treated mice, whereas high values were still measured in those treated with LCS3 (9.35 +/- 1.20 x 10(6) PMN per mouse, n = 12, P < 0.05). A similar effect was also found following sub-chronic treatment of mice with LCPS1: 6.48 +/- 0.10 x 10(6) PMN per mouse, vs. 2.77 +/- 1.20 and 2.64 +/- 0.49 x 10(6) PMN per mouse for PBS- and NSS-treated groups (n = 7, P < 0.05). Most markers of inflammation were also increased in the lavage fluids of LCS3-treated mice: MPO and elastase showed a 2.47 fold and 17 fold increase, respectively (P < 0.05 in both cases); TNF-alpha showed a 11.1 fold increase (P < 0.05) whereas the IL-1 alpha levels were not significantly modified. PGE2 was still detectable in most (5 out of 7) of the mice treated with LCS3 but only in 2 out of 7 of the NSS-treated mice. 5. Intradermal injection of 50% ZAS caused a significant increase in the 2 hoedema formation in the skin of LCS3-treated mice in comparison to PBS- and NSS-treated animals: 16.7 +/- 1.5 microliters vs. 10.8 +/- 1.2 microliters and 10.2 +/- 1.0 microliters, respectively (n = 14 mice per group, P < 0.05). ZAS-induced oedema had subsided by 24 h in control animals but a residual significant amount of extravasation was still detectable in LCS3-treated mice: 4.4 +/- 0.8 microliters (P < 0.05). 6. A recently described model driven by endogenous glucocorticoids is the blood neutrophilia observed following administration of PAF. In our experimental conditions, a single bolus of PAF (100 ng, i.v.) provoked a marked neutrophilia at 2 h (2.43 and 2.01 fold) in NSS- and PBS-treated mice (n = 11), respectively, which was significantly attenuated in the animals treated with LCS3: 1.26 fold increase in circulating PMN (n = 11, P < 0.01 vs. NSS- and PBS-groups). 7. Intraperitoneal injection of IL-1 beta (5 micrograms kg-1) caused a marked increase in circulating plasma CCS by 2 h, to a similar extent in all experimental groups. In contrast, measurement of CCS levels in the plasma of mice bearing air-pouches inflamed with zymosan revealed significant differences between LCS3 and NSS-treated mice at the 4 h time-point: 198 +/- 26 ng ml-1 vs. 110 +/- 31 ng ml-1 (n = 8, P < 0.05). 8. In conclusion, we found a remarkable exacerbation of the inflammatory process with respect to both humoral and cellular components in mice passively immunised agains
Nitric oxide (NO.) is a pro-inflammatory effector molecule in certain inflammatory diseases, including arthritis. We investigated the production of NO. by adjuvant arthritis (AA) synovial macrophages, and studied the effects of a NO. synthase inhibitor. N-iminoethyl-L-ornithine (L-NIO). Compared to control rats, rats treated with L-NIO in vivo exhibited significantly lower articular index (p < 0.05), paw volume (p < 0.05), and synovial fluid cell count (p < 0.05). No effect on cutaneous delayed-type hypersensitivity to the disease-initiating antigen was observed. Inducible NO. synthase (iNOS) was detected in AA synovial macrophages, and cultured AA synovial macrophage iNOS levels were increased by a factor of 138 +/- 17% (p < 0.01) by 1 microgram/ml LPS in vitro. Constitutive NO. production by AA synovial macrophages (43 +/- 1 nmol/10(5) cells/24 h) was significantly inhibited by 10 nM L-NIO in vitro (32 +/- 0.5, p < 0.01). NO. production induced by 1 microgram/ml LPS (48 +/- 2) was also decreased by L-NIO (39 +/- 2, p < 0.05). In vivo L-NIO treatment also inhibited alveolar macrophage NO. production (p < 0.05). The ability of L-NIO to decrease iNOS-mediated synovial macrophage NO. production and inhibit the clinical parameters of AA implicate macrophage-derived NO. in the pathogenesis of this disease.