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LPS-mediated lung injury is not attenuated by antagonists to P-selectin or by DNase treatment. Mice were treated with antibodies to P-selectin (30 m g) or GPIIb/IIIa (100 m g), or DNase (1 m g) before LPS inhalation, and killed 4 hours later. ( A ) Quantification of intravascular ( top ), interstitial ( middle ), and alveolar neutrophils ( bottom ). ( B ) Protein concentration ( top ), fluorescein isothiocyanate (FITC)–dextran clearance ( middle ), and elastase ( bottom , uniform bars ) and myeloperoxidase (MPO) activity ( bottom , hatched bars ) in bronchoalveolar lavage fluids. n 1⁄4 8–10 for each bar. Statistical significance was tested using one-way analysis of variance with Dunnett post hoc test. *Indicates significant difference compared with LPS- treated animals.
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Acute lung injury (ALI) causes high mortality, but its molecular mechanisms and therapeutic options remain ill-defined. Gram-negative bacterial infections are the main cause of ALI, leading to lung neutrophil infiltration, permeability increases, deterioration of gas exchange, and lung damage. Platelets are activated during ALI, but insights into t...
Contexts in source publication
Context 1
... lung injury (ALI) is a life-threatening disease with an age- adjusted incidence of 86.2 per 100,000 person-years (1). Despite innovations in intensive care medicine, the mortality of ALI remains approximately 40%. ALI is characterized by an increased permeability of the alveolar–capillary barrier, resulting in lung edema with protein-rich fluid and consequently in impaired arterial oxygenation. A major cause for development of ALI is sepsis, wherein gram-negative bacteria are the dominat- ing factor. LPS inhalation mimics human gram-negative ALI, leading to recruitment of neutrophils, pulmonary edema, and finally impairment of gas exchange (2). Recruitment of neutrophils is a key event in development of ALI (3) resulting in plasma leakage and deterioration of oxygenation. The importance of neutrophils in ALI is supported by studies, where lung injury was abolished or reversed by depletion of neutrophils (4, 5). Much of the neutrophil-dependent ALI is thought to be mediated by granule proteins released from activated neutrophils. For example, azurocidin and a -defensins have been found to directly affect permeability changes (6, 7), whereas proteases of neutrophilic origin, such as neutrophil elastase, have been implicated in the degrada- tion of surfactant proteins, epithelial cell apoptosis, and coagulation (8, 9). Under inflammatory conditions, platelets prominently interact with neutrophils, thus promoting their recruitment by such mechanisms as formation of platelet–neutrophil aggregates by employment of PSGL-1 and P-selectin (10) or deposition of platelet-derived chemokines, such as CCL5 and CXCL4 (11). Recent studies provide evidence for the significance of platelets in mouse models of acid-induced ALI (12) and transfusion-related ALI (5). These prompted us to systematically investigate the importance of platelet–neutrophil interactions in various models of ALI. Herein, we demonstrate a dominant role of platelet-derived chemokines and their heteromer formation in neutrophil lung infiltration, edema formation, and tissue damage, a finding further translated into a therapeutic approach. The involvement of neutrophils as effector cells in ALI is well defined (3). Recently, reports accumulated suggesting the importance of platelets in acid-induced and transfusion-related ALI (5, 12). Such data, however, are not available for sepsis models of ALI. Hence, we exposed C57Bl/6 mice to aerosolized LPS and moni- tored neutrophil recruitment, plasma leakage, lung ultrastructure, and protease activity in the BAL fluid (BALF) (Figure 1, see Figure E1). Such treatment increased the number of intravascular, interstitial, and alveolar neutrophils (Figure 1A) as analyzed by flow cytometry of lung homogenates ( see Figure E2) (13). Both the protein concentration and the clearance of fluorescent dextran were found to be increased in the BALF by LPS treatment, indicative of enhanced plasma leakage and edema formation (Figure 1B). Furthermore, the activity of neutrophil-derived elastase and myeloperoxidase was elevated in the BALF of LPS-treated animals (Figure 1B). Histologic and ultrastructural analyses of lungs after LPS exposure revealed alveolar septal thickening, accumulation of inflammatory cells in the interstitium and the alveoli, and influx of protein-rich fluid into the alveolar space compared with control mice exposed to aerosolized saline (Figure 1C). To assess the individual contribution of neutrophils and platelets to ALI development, each population was depleted individually ( see Table E2) (17). Neutrophil depletion abolished alveolar fluid efflux and structural changes confirming the importance of neutrophils in ALI. Moreover, depletion of platelets almost fully abrogated the accumulation of neutrophils in the interstitium and the alveoli, permeability changes, protease release, and structural changes of the lung tissue (Figures 1A–1C). Finally, we examined whether depletion of both cell subsets would result in an additive effect. However, depletion of neutrophils and platelets together had no such effect (Figures 1A and 1B), suggesting that both cell types act in a sequential context. Both P-selectin and GPIIb/IIIa have been implicated in the formation of platelet–neutrophil complexes and subsequent neutrophil adhesion. To dissect mechanisms underlying the platelet–neutrophil axis dependent lung injury induced by LPS we treated mice with antagonists to P-selectin or an antibody to platelet glycoprotein GPIIb/IIIa before endotoxin inhalation. P-selectin antagonists failed to reduce the intravascular, interstitial, and alveolar accumulation of neutrophils (Figure 2A). Furthermore, inhibition of P-selectin did not affect edema formation and protease release (Figure 2B). Similarly, antibodies to GPIIb/IIIa did not exert effects on alveolar protease activity, plasma leakage, or neutrophil tissue accumulation. However, the intravascular neutrophil counts were significantly reduced by pretreatment with GPIIb/IIIa antibodies (Figure 2). LPS-mediated activation of platelets stimulates binding of platelets to neutrophils with subsequent release of DNA-containing neutrophil extracellular traps, a mechanism that may be linked to the development of ALI (9, 19). In addition, neutrophil extracellular traps release might link to permeability changes as observed in ALI (20). To degrade DNA-containing neutrophil extracellular traps, we injected a bolus of DNase before LPS exposure. However, such treatment failed to reduce LPS-mediated ALI formation (Figure 2). As an alternative mechanism, we sought to explore the role of platelet-derived chemokines in neutrophil recruitment and ALI formation. Specifically, platelet-derived CCL5 and CXCL4 were previously shown to mediate monocyte and neutrophil adhesion in large arteries (11, 17). Hence, we investigated the deposition of CCL5 and CXCL4 on microvascular lung endothelium by use of intravital microscopy using established protocols (16, 17). By this approach we could evidence the increased endothelial presentation of CCL5 and CXCL4 after LPS inhalation (Figure 3A). To further investigate the role of these chemokines in ALI development, ...
Context 2
... lung injury (ALI) is a life-threatening disease with an age- adjusted incidence of 86.2 per 100,000 person-years (1). Despite innovations in intensive care medicine, the mortality of ALI remains approximately 40%. ALI is characterized by an increased permeability of the alveolar–capillary barrier, resulting in lung edema with protein-rich fluid and consequently in impaired arterial oxygenation. A major cause for development of ALI is sepsis, wherein gram-negative bacteria are the dominat- ing factor. LPS inhalation mimics human gram-negative ALI, leading to recruitment of neutrophils, pulmonary edema, and finally impairment of gas exchange (2). Recruitment of neutrophils is a key event in development of ALI (3) resulting in plasma leakage and deterioration of oxygenation. The importance of neutrophils in ALI is supported by studies, where lung injury was abolished or reversed by depletion of neutrophils (4, 5). Much of the neutrophil-dependent ALI is thought to be mediated by granule proteins released from activated neutrophils. For example, azurocidin and a -defensins have been found to directly affect permeability changes (6, 7), whereas proteases of neutrophilic origin, such as neutrophil elastase, have been implicated in the degrada- tion of surfactant proteins, epithelial cell apoptosis, and coagulation (8, 9). Under inflammatory conditions, platelets prominently interact with neutrophils, thus promoting their recruitment by such mechanisms as formation of platelet–neutrophil aggregates by employment of PSGL-1 and P-selectin (10) or deposition of platelet-derived chemokines, such as CCL5 and CXCL4 (11). Recent studies provide evidence for the significance of platelets in mouse models of acid-induced ALI (12) and transfusion-related ALI (5). These prompted us to systematically investigate the importance of platelet–neutrophil interactions in various models of ALI. Herein, we demonstrate a dominant role of platelet-derived chemokines and their heteromer formation in neutrophil lung infiltration, edema formation, and tissue damage, a finding further translated into a therapeutic approach. The involvement of neutrophils as effector cells in ALI is well defined (3). Recently, reports accumulated suggesting the importance of platelets in acid-induced and transfusion-related ALI (5, 12). Such data, however, are not available for sepsis models of ALI. Hence, we exposed C57Bl/6 mice to aerosolized LPS and moni- tored neutrophil recruitment, plasma leakage, lung ultrastructure, and protease activity in the BAL fluid (BALF) (Figure 1, see Figure E1). Such treatment increased the number of intravascular, interstitial, and alveolar neutrophils (Figure 1A) as analyzed by flow cytometry of lung homogenates ( see Figure E2) (13). Both the protein concentration and the clearance of fluorescent dextran were found to be increased in the BALF by LPS treatment, indicative of enhanced plasma leakage and edema formation (Figure 1B). Furthermore, the activity of neutrophil-derived elastase and myeloperoxidase was elevated in the BALF of LPS-treated animals (Figure 1B). Histologic and ultrastructural analyses of lungs after LPS exposure revealed alveolar septal thickening, accumulation of inflammatory cells in the interstitium and the alveoli, and influx of protein-rich fluid into the alveolar space compared with control mice exposed to aerosolized saline (Figure 1C). To assess the individual contribution of neutrophils and platelets to ALI development, each population was depleted individually ( see Table E2) (17). Neutrophil depletion abolished alveolar fluid efflux and structural changes confirming the importance of neutrophils in ALI. Moreover, depletion of platelets almost fully abrogated the accumulation of neutrophils in the interstitium and the alveoli, permeability changes, protease release, and structural changes of the lung tissue (Figures 1A–1C). Finally, we examined whether depletion of both cell subsets would result in an additive effect. However, depletion of neutrophils and platelets together had no such effect (Figures 1A and 1B), suggesting that both cell types act in a sequential context. Both P-selectin and GPIIb/IIIa have been implicated in the formation of platelet–neutrophil complexes and subsequent neutrophil adhesion. To dissect mechanisms underlying the platelet–neutrophil axis dependent lung injury induced by LPS we treated mice with antagonists to P-selectin or an antibody to platelet glycoprotein GPIIb/IIIa before endotoxin inhalation. P-selectin antagonists failed to reduce the intravascular, interstitial, and alveolar accumulation of neutrophils (Figure 2A). Furthermore, inhibition of P-selectin did not affect edema formation and protease release (Figure 2B). Similarly, antibodies to GPIIb/IIIa did not exert effects on alveolar protease activity, plasma leakage, or neutrophil tissue accumulation. However, the intravascular neutrophil counts were significantly reduced by pretreatment with GPIIb/IIIa antibodies (Figure 2). LPS-mediated activation of platelets stimulates binding of platelets to neutrophils with subsequent release of DNA-containing neutrophil extracellular traps, a mechanism that may be linked to the development of ALI (9, 19). In addition, neutrophil extracellular traps release might link to permeability changes as observed in ALI (20). To degrade DNA-containing neutrophil extracellular traps, we injected a bolus of DNase before LPS exposure. However, such treatment failed to reduce LPS-mediated ALI formation (Figure 2). As an alternative mechanism, we sought to explore the role of platelet-derived chemokines in neutrophil recruitment and ALI formation. Specifically, platelet-derived CCL5 and CXCL4 were previously shown to mediate monocyte and neutrophil adhesion in large arteries (11, 17). Hence, we investigated the deposition of CCL5 and CXCL4 on microvascular lung endothelium by use of intravital microscopy using established protocols (16, 17). By this approach we could evidence the increased endothelial presentation of CCL5 and CXCL4 after LPS inhalation (Figure 3A). To further investigate the role of these chemokines in ALI development, ...
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The chemokines CCL5 and CXCL4 are deposited by platelets onto endothelial cells, inducing monocyte arrest. Here, the fate of CCL5 and CXCL4 after endothelial deposition was investigated. Human umbilical vein endothelial cells (HUVECs) and EA.hy926 cells were incubated with CCL5 or CXCL4 for up to 120 min, and chemokine uptake was analyzed by micros...
Citations
... Moreover, activated platelets facilitate the deposition of chemokines such as CCL5 and PF4 onto the surface of endothelial cells, thereby promoting the recruitment of leukocytes. Furthermore, platelet-derived CCL5 and PF4 heterodimers have been found to augment the ability of lung tissue to attract neutrophils [111,112]. Other studies found that liver regeneration is associated with platelet-endothelial interactions [113]. ...
Sepsis, a life-threatening condition characterized by organ dysfunction, results from a complex series of pathophysiological mechanisms including immune dysfunction, an uncontrolled inflammatory response, and coagulation abnormalities. It is a major contributor to global mortality and severe disease development. Platelets, abundant in the circulatory system, are sensitive to changes in the body's internal environment and are among the first cells to respond to dysregulated pro-inflammatory and pro-coagulant reactions at the onset of sepsis. In the initial stages of sepsis, the coagulation cascade, inflammatory response, and endothelial tissue damage perpetually trigger platelet activation. These activated platelets then engage in complex inflammatory and immune reactions, potentially leading to organ dysfunction. Therefore, further research is essential to fully understand the role of platelets in sepsis pathology and to develop effective therapeutic strategies targeting the associated pathogenic pathways. This review delves into the involvement of platelets in sepsis and briefly outlines the clinical applications of associated biomarkers.
... Sepsis is de ned as a life-threatening organ dysfunction syndrome caused by a dysregulated host response to infection [1,2] . In recent years, an increasing number of studies have shown that platelets are involved in the pathophysiological processes of sepsis and play an important role in organ damage [2][3][4] . ...
Objective To compare the cytological characteristics of bone marrow cells in patients with sepsis with or without thrombocytopenia and their clinical significance.
Methods Ninety-one patients diagnosed with sepsis in the Department of General Practice, Sun Yat-sen Memorial Hospital of Sun Yat-sen University between February 2016 and December 2022 were retrospectively recruited in this study, and their clinical parameters, bone marrow smears and examination results, and blood routine examination results were collected. Patients were divided into thrombocytopenia (TP) group and non-thrombocytopenia (non-TP) group according to the count of peripheral blood platelets, the clinical parameters and the cytological characteristics of bone marrow cells were compared between two groups.
Results Hypoplasia of marrow was more frequent in TP group (26.5%, 13/49) compared to the non-TP group (4.8%, 2/42; P = 0.005) and the occurrence of reduced megakaryocyte or dysmaturity was more common in TP group (31/49, 63.3%) compared to that in the non-TP group (13/42, 31.0%; P = 0.002). The number of bone marrow megakaryocytes was positively correlated with the count of peripheral blood platelets in all patients (r = 0.2884, P = 0.0056) and the non-TP group (r = 0.3316, p = 0.0319), but there was no correlation in the TP group; Moreover, the hemoglobin level, the white blood cell, granulocyte, lymphocyte, and monocyte count were lower in TP group than those in non-TP group. Furthermore，a significant higher incidence of MODS was observed in TP group (29/49, 59.2%) compared to non-TP group (14/42, 33.3%; P = 0.014) and the mean SOFA scores in TP group were higher than that in non-TP group (9.69 ± 3.92 vs 7.83±3.87, P = 0.026).
Conclusions The decreased production of platelets, which is secondary to marrow cell failure, is an exact mechanism of sepsis-associatedthrombocytopenia. Thus, precautions and intervention should been taken early during the treatment.
... ALI is linked with MPO activity in the lungs, and the extravasation of neutrophils is a key indicator of inflammatory and immune reactions in damaged lung tissue (Grommes et al. 2012). MPO activity in the lungs also serves as a dependable marker of neutrophil infiltration (Zhang et al. 2017a, b). ...
Sepsis is a systemic illness for which there are no effective preventive or therapeutic therapies. Zerumbone, a natural molecule, has anti-oxidative and anti-inflammatory properties that may help to prevent sepsis. In the present study, we have assessed the protective effect of zerumbone against sepsis-induced acute lung injury (ALI) and its underlying mechanisms. During the experiment, mice were divided into five groups: a sham group, a sepsis-induced ALI group, and three sepsis groups that are pre-treated with zerumbone at different concentrations. We found that zerumbone greatly decreased the sepsis-induced ALI using histological investigations. Also, zerumbone treatment reduced the sepsis-induced inflammatory cytokine concentrations as well as the number of infiltrating inflammatory cells in BALF compared to non-treated sepsis animals. The zerumbone-pretreated sepsis groups had reduced pulmonary myeloperoxidase (MPO) activity than the sepsis groups. Moreover, the mechanism underlying the protective action of zerumbone on sepsis is accomplished by the activation of antioxidant genes such as nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), superoxide dismutase (SOD), and heme oxygenase 1 (HO-1). The obtained results revealed that zerumbone inhibited the sepsis-induced ALI through its anti-inflammatory and antioxidative activity via inhibition of the NF-κB pathway and activation of HO-1 pathway. Our findings demonstrate that zerumbone pretreatment suppresses sepsis-induced ALI via antioxidative activities and anti-inflammatory, implying that zerumbone could be a viable preventive agent for sepsis-induced ALI.
Graphical Abstract
... 40,41 In addition, studies have reported that chemokine-mediated signal pathways play a key role in the pathogenesis of ALI. [42][43][44] The above information supports our analysis of the biological information. In our study, WGCNA was used to analyze 9043 mRNA gene modules, and the pink module was found be highly correlated with CLP-induced ALI. ...
Background
Acute lung injury (ALI) is associated with a high mortality rate; however, the underlying molecular mechanisms are poorly understood. The purpose of this study was to investigate the expression profile and related networks of long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs in lung tissue exosomes obtained from sepsis-induced ALI.
Methods
A mouse model of sepsis was established using the cecal ligation and puncture method. RNA sequencing was performed using lung tissue exosomes obtained from mice in the sham and CLP groups. Hematoxylin-eosin staining, Western blotting, immunofluorescence, quantitative real-time polymerase chain reaction, and nanoparticle tracking analysis were performed to identify relevant phenotypes, and bioinformatic algorithms were used to evaluate competitive endogenous RNA (ceRNA) networks.
Results
Thirty lncRNA-miRNA-mRNA interactions were identified, including two upregulated lncRNAs, 30 upregulated miRNAs, and two downregulated miRNAs. Based on the expression levels of differentially expressed mRNAs(DEmRNAs), differentially expressed LncRNAs(DELncRNAs), and differentially expressed miRNAs(DEmiRNAs), 30 ceRNA networks were constructed.
Conclusion
Our study revealed, for the first time, the expression profiles of lncRNA, miRNA, and mRNA in exosomes isolated from the lungs of mice with sepsis-induced ALI, and the exosome co-expression network and ceRNA network related to ALI in sepsis.
... CD61, also known as integrin β 3 chain, is a transmembrane glycoprotein expressed on megakaryocytes and platelets (Meehan et al. 2008). The lack of platelet spread in CD34 KO mice explains the lack of long-term protection against lung edema, since, in addition to their role in the release of platelets-derived chemokines, platelets can protect the basal barrier of alveolar capillaries, contributing to their integrity and reduced permeability (Dewitte et al. 2017;Grommes et al. 2012). ...
CD34 has spear-headed the field of basic research and clinical transplantation since the first reports of its expression on hematopoietic stem cells (HSCs). Expressed in mice, humans, rats and other species, CD34 has been used for more than 40 years as a hematopoietic stem and progenitor cell marker. It was later found that muscle satellite cells and epidermal precursors can also be identified with the aid of CD34. Despite the usefulness of CD34 as a marker of HSCs, its overall purpose in animal physiology has remained unclear. This review recaptures CD34 structure, evolutionary conservation, proposed functions, and role in lung inflammation, to describe current research findings and to provide guidance for future studies on CD34.
... Heterophilic interactions between CXCL4 and CCL5 promote neutrophil recruitment in an LPS-induced acute lung injury model and accelerate atherosclerosis by triggering monocyte arrest on the endothelium [70][71][72]. Mechanistically, the GAG-binding capacity of the CCL5•CXCL4 heterodimer anchored the CCR1 receptor at the endothelial cell surface, thereby promoting the recruitment of immune cells. Contrary to CXCL4, combined stimulation of CXCL4L1 and CCL5 heterodimer failed to enhance the leukocyte recruitment both in vitro and in an in vivo peritoneal recruitment assay [73]. ...
Chemoattractant cytokines or chemokines are proteins involved in numerous biological activities. Their essential role consists of the formation of gradient and (immune) cell recruitment. Chemokine biology and its related signaling system is more complex than simple ligand–receptor interactions. Beside interactions with their cognate and/or atypical chemokine receptors, and glycosaminoglycans (GAGs), chemokines form complexes with themselves as homo-oligomers, heteromers and also with other soluble effector proteins, including the atypical chemokine MIF, carbohydrate-binding proteins (galectins), damage-associated molecular patterns (DAMPs) or with chemokine-binding proteins such as evasins. Likewise, nucleic acids have been described as binding targets for the tetrameric form of CXCL4. The dynamic balance between monomeric and dimeric structures, as well as interactions with GAGs, modulate the concentrations of free chemokines available along with the nature of the gradient. Dimerization of chemokines changes the canonical monomeric fold into two main dimeric structures, namely CC- and CXC-type dimers. Recent studies highlighted that chemokine dimer formation is a frequent event that could occur under pathophysiological conditions. The structural changes dictated by chemokine dimerization confer additional biological activities, e.g., biased signaling. The present review will provide a short overview of the known functionality of chemokines together with the consequences of the interactions engaged by the chemokines with other proteins. Finally, we will present potential therapeutic tools targeting the chemokine multimeric structures that could modulate their biological functions.
... Von Hundelshausen et al. extensively studied how human chemokines interact with each other and demonstrated their relevance in enhancing receptor triggering or inhibiting receptor activities (43). Several studied performed in vivo highlighted the importance of disrupting the heterocomplex formation to ameliorate inflammation (44)(45)(46). ...
Leukocyte trafficking is mainly governed by chemokines, chemotactic cytokines, which can be concomitantly produced in tissues during homeostatic conditions or inflammation. After the discovery and characterization of the individual chemokines, we and others have shown that they present additional properties. The first discoveries demonstrated that some chemokines act as natural antagonists on chemokine receptors, and prevent infiltration of leukocyte subsets in tissues. Later on it was shown that they can exert a repulsive effect on selective cell types, or synergize with other chemokines and inflammatory mediators to enhance chemokine receptors activities. The relevance of the fine-tuning modulation has been demonstrated in vivo in a multitude of processes, spanning from chronic inflammation to tissue regeneration, while its role in the tumor microenvironment needs further investigation. Moreover, naturally occurring autoantibodies targeting chemokines were found in tumors and autoimmune diseases. More recently in SARS-CoV-2 infection, the presence of several autoantibodies neutralizing chemokine activities distinguished disease severity, and they were shown to be beneficial, protecting from long-term sequelae. Here, we review the additional properties of chemokines that influence cell recruitment and activities. We believe these features need to be taken into account when designing novel therapeutic strategies targeting immunological disorders.
... Acute lung injury after infection is also related to neutrophil recruitment mediated by platelet-and platelet-derived chemokines, specifically CCL5 and CXCL4, and their heteromerization. [131]. Antibodies against CCL5 and CXCL4 reduced neutrophil recruitment and disturbed CCL5-CXCL4 heteromer formation to contribute to lung recovery in various ALI situations. ...
Various immune cells participate in repair and regeneration following tissue injury or damage, orchestrating tissue inflammation and regeneration processes. A deeper understanding of the immune system's involvement in tissue repair and regeneration is critical for the development of successful reparatory and regenerative strategies. Here we review recent technologies that facilitate cell-based and biomaterial-based modulation of the immune systems for tissue repair and regeneration. First, we summarize the roles of various types of immune cells in tissue repair. Second, we review the principle, examples, and limitations of regulatory T (Treg) cell-based therapy, a representative cell-based immunotherapy. Finally, we discuss biomaterial-based immunotherapy strategies that aim to modulate immune cells using various biomaterials for tissue repair and regeneration.
... Surprisingly, the explored compounds did not modulate mRNA levels of these pro-inflammatory cytokines; only SM 2.5-fold down-regulated Il1b expression compared with the vehicle-treated group (p = 0.029, Fig. 4C). Analysis of mRNA levels of chemokines Cxcl10 and Ccl5 (Rantes), controlling influx of inflammatory cells into the inflamed lungs [41,42], revealed that ALI induction significantly up-regulated expression of Cxcl10 and had no effect on the level of Ccl5, whereas the administration of soloxolone derivatives significantly reduced mRNA levels of both chemokines in lung tissue by an average of 3.2 (SAO, S, SM) and 1.8 (S, SM) times compared with vehicle-treated mice, respectively (Fig. 4C). Besides, tested compounds had no effect on the expression of Ptgs2, encoding cyclooxygenase-2 (COX-2) up-regulated in LPS-challenged lungs, and significantly inhibited the expression of Nos2, protein product of which (iNOS) is deeply implicated in ALI pathology [43] (Fig. 4C). ...
... Neutralization of Cxcl10 by anti-Cxcl10 antibody significantly ameliorated the severity of ALI in rodent models [41,78], and mice with a knockout of Cxcl10 demonstrated improved severity and survival of non-viral and viral ARDS [77]. Along with Cxcl10, ALI development is associated with up-regulation of Ccl5 expression [82] and Ccl5-Cxcl4 heteromer formation [42] in inflamed lungs, the latter of which is critical to ALI: pharmacological disruption of pro-inflammatory interactions of Ccl5-Cxcl4 led to a significant reduction of alveolar neutrophil counts and full abrogation of lung edema formation in LPS-treated mice [42]. Mcp1 playing a pivotal role in monocyte chemotaxis is also tightly involved in the regulation of respiratory tract inflammation [83] and is crucial for ALI pathogenesis: the blockage of the synthesis of Mcp1 or its interaction with Ccr2 by bindarit and RS102895, respectively, significantly alleviated ALI in rodents [84,85]. ...
... Neutralization of Cxcl10 by anti-Cxcl10 antibody significantly ameliorated the severity of ALI in rodent models [41,78], and mice with a knockout of Cxcl10 demonstrated improved severity and survival of non-viral and viral ARDS [77]. Along with Cxcl10, ALI development is associated with up-regulation of Ccl5 expression [82] and Ccl5-Cxcl4 heteromer formation [42] in inflamed lungs, the latter of which is critical to ALI: pharmacological disruption of pro-inflammatory interactions of Ccl5-Cxcl4 led to a significant reduction of alveolar neutrophil counts and full abrogation of lung edema formation in LPS-treated mice [42]. Mcp1 playing a pivotal role in monocyte chemotaxis is also tightly involved in the regulation of respiratory tract inflammation [83] and is crucial for ALI pathogenesis: the blockage of the synthesis of Mcp1 or its interaction with Ccr2 by bindarit and RS102895, respectively, significantly alleviated ALI in rodents [84,85]. ...
The anti-inflammatory potential of three cyanoenone-containing triterpenoids, including soloxolone methyl (SM), soloxolone (S) and its novel derivative bearing at the C-30 amidoxime moiety (SAO), was studied in murine models of acute inflammation. It was found that the compounds effectively suppressed the development of carrageenan-induced paw edema and peritonitis as well as lipopolysaccharide (LPS)-driven acute lung injury (ALI) with therapeutic outcomes comparable with that of the reference drugs indomethacin and dexamethasone. Non-immunogenic carrageenan-stimulated inflammation was more sensitive to the transformation of C-30 of SM compared with immunogenic LPS-induced inflammation: the anti-inflammatory properties of the studied compounds against carrageenan-induced paw edema and peritonitis decreased in the order of SAO > S > > SM, whereas the efficiency of these triterpenoids against LPS-driven ALI was similar (SAO ≈ S ≈ SM). Further studies demonstrated that soloxolone derivatives significantly inhibited a range of immune-related processes, including granulocyte influx and the expression of key pro-inflammatory cytokines and chemokines in the inflamed sites as well as the functional activity of macrophages. Moreover, SM was found to prevent inflammation-associated apoptosis of A549 pneumocytes and effectively inhibited the protease activity of thrombin (IC50 = 10.3 µM) tightly associated with rodent inflammatome. Taken together, our findings demonstrate that soloxolone derivatives can be considered as novel promising anti-inflammatory drug candidates with multi-targeted mechanism of action.
... TLR4-mediated platelet activation increases endothelial cell adhesion at the site of inflammation (66) and promotes neutrophil activation, exosmosis, and aggregation by expressing higher levels of P-selectin ( Figure 1) (134). Platelet-derived chemokine heterodimers (of CXCL4 and CXCL5) are also important for neutrophil recruitment (135), and endothelial presentation of CXCL5 depends on platelets (136). Activated platelets interact with neutrophils through b 2 -integrin LFA-1, thereby enhancing neutrophilic activation and lowering the threshold for NETs release (137,138). ...
Sepsis is defined as a life-threatening dysfunction due to a dysregulated host response to infection. It is a common and complex syndrome and is the leading cause of death in intensive care units. The lungs are most vulnerable to the challenge of sepsis, and the incidence of respiratory dysfunction has been reported to be up to 70%, in which neutrophils play a major role. Neutrophils are the first line of defense against infection, and they are regarded as the most responsive cells in sepsis. Normally, neutrophils recognize chemokines including the bacterial product N-formyl-methionyl-leucyl-phenylalanine (fMLP), complement 5a (C5a), and lipid molecules Leukotriene B4 (LTB4) and C-X-C motif chemokine ligand 8 (CXCL8), and enter the site of infection through mobilization, rolling, adhesion, migration, and chemotaxis. However, numerous studies have confirmed that despite the high levels of chemokines in septic patients and mice at the site of infection, the neutrophils cannot migrate to the proper target location, but instead they accumulate in the lungs, releasing histones, DNA, and proteases that mediate tissue damage and induce acute respiratory distress syndrome (ARDS). This is closely related to impaired neutrophil migration in sepsis, but the mechanism involved is still unclear. Many studies have shown that chemokine receptor dysregulation is an important cause of impaired neutrophil migration, and the vast majority of these chemokine receptors belong to the G protein-coupled receptors (GPCRs). In this review, we summarize the signaling pathways by which neutrophil GPCR regulates chemotaxis and the mechanisms by which abnormal GPCR function in sepsis leads to impaired neutrophil chemotaxis, which can further cause ARDS. Several potential targets for intervention are proposed to improve neutrophil chemotaxis, and we hope that this review may provide insights for clinical practitioners.
