Soluble Gp130 Research Articles

Preeclampsia Status Controls Interleukin-6 and Soluble IL-6 Receptor Release from Neutrophils and Endothelial Cells: Relevance to Increased Inflammatory Responses.

Increased neutrophil–endothelial binding and inflammatory responses are significant pathophysiological events in the maternal vascular system in preeclampsia, a hypertensive disorder in human pregnancy. Interleukin 6 (IL-6) and its soluble receptors (soluble IL-6R (sIL-6R) and soluble gp130 (sgp130)) are critical inflammatory mediators. During pregnancy, maternal IL-6 and sgp130 levels were increased, but sIL-6R levels were decreased, in women with preeclampsia compared to normotensive pregnant women. However, little is known about differences in IL-6, sIL-6R, and sgp130 production by neutrophils and endothelial cells between normal pregnancy and preeclampsia. To study this, we isolated neutrophils and cultured human umbilical vein endothelial cells (HUVECs) from normal and preeclamptic pregnancies. Production of IL-6, sIL-6R, and sgp130 was measured. The role of placental factor(s)-mediated neutrophil production of IL-6, sIL-6R, and sgp130 was also determined by pretreating neutrophils with placental conditioned medium generated from placental villous cultures. We found that IL-6 and sgp130 were mainly produced by endothelial cells, while sIL-6R was mainly produced by neutrophils. Endothelial cells from preeclampsia produced significantly more IL-6 and sgp130, and neutrophils from preeclampsia produced significantly less sIL-6R than normal pregnancy cells. Interestingly, production of IL-6, sIL-6R, and sgp130 were time-dependently increased when neutrophils and endothelial cells were co-cultured. We also found that neutrophils from normal pregnancies produced more IL-6, but less sIL-6R, after being primed by preeclamptic-placental conditioned medium. These results demonstrated that neutrophils and endothelial cells have different capacities in producing IL-6, sIL-6R, and sgp130 between normal pregnancy and preeclampsia. These results also provide evidence that the placenta plays a role in inducing neutrophil activation in preeclampsia.

Role of Interleukin-6 in Vascular Health and Disease.

IL-6 is usually described as a pleiotropic cytokine produced in response to tissue injury or infection. As a pro-inflammatory cytokine, IL-6 activates innate and adaptative immune responses. IL-6 is released in the innate immune response by leukocytes as well as stromal cells upon pattern recognition receptor activation. IL-6 then recruits immune cells and triggers B and T cell response. Dysregulated IL-6 activity is associated with pathologies involving chronic inflammation and autoimmunity, including atherosclerosis. However, IL-6 is also produced and released under beneficial conditions, such as exercise, where IL-6 is associated with the anti-inflammatory and metabolic effects coupled with physical adaptation to intense training. Exercise-associated IL-6 acts on adipose tissue to induce lipogenesis and on arteries to induce adaptative vascular remodeling. These divergent actions could be explained by complex signaling networks. Classical IL-6 signaling involves a membrane-bound IL-6 receptor and glycoprotein 130 (gp130), while trans-signaling relies on a soluble version of IL-6R (sIL-6R) and membrane-bound gp130. Trans-signaling, but not the classical pathway, is regulated by soluble gp130. In this review, we discuss the similarities and differences in IL-6 cytokine and myokine signaling to explain the differential and opposite effects of this protein during inflammation and exercise, with a special focus on the vascular system.

Cannabis Use Is Associated With Increased Levels of Soluble gp130 in Schizophrenia but Not in Bipolar Disorder.

The complex effects of plant cannabinoids on human physiology is not yet fully understood, but include a wide spectrum of effects on immune modulation. The immune system and its inflammatory effector pathways are recently emerging as possible causative factors in psychotic disorders. The present study aimed to investigate whether self-administered Cannabis use was associated with changes in circulating immune and neuroendocrine markers in schizophrenia (SCZ) and bipolar disorder (BD) patients. A screening of 13 plasma markers reflecting different inflammatory pathways was performed in SCZ (n = 401) and BD patients (n = 242) after subdividing each group into Cannabis user and non-user subgroups. We found that i) soluble gp130 (sgp130) concentrations were significantly elevated among Cannabis users in the SCZ group (p = 0.002) after multiple testing correction, but not in BD. ii) Nominally significant differences were observed in the levels of IL-1RA (p = 0.0059), YKL40 (p = 0.0069), CatS (p = 0.013), sTNFR1 (p = 0.031), and BDNF (p = 0.020), where these factors exhibited higher plasma levels in Cannabis user SCZ patients than in non-users. iii) These differences in systemic levels were not reflected by altered mRNA expression of genes encoding sgp130, IL-1RA, YKL40, CatS, sTNFR1, and BDNF in whole blood. Our results show that Cannabis self-administration is associated with markedly higher sgp130 levels in SCZ, but not in BD, and that this phenomenon is independent of the modulation of peripheral immune cells. These findings warrant further investigation into the potential IL-6 trans-signaling modulatory, anti-inflammatory, neuroimmune, and biobehavioral-cognitive effects of Cannabis use in SCZ.

FRI0113 THE BASELINE SOLUBLE GP130 IS ASSOCIATED WITH THE RESPONSE OF RHEUMATOID ARTHRITIS PATIENTS TO SARILUMAB

Background:IL-6 contributes significantly to the chronic inflammatory process of rheumatoid arthritis (RA). Sarilumab (SRL), a human anti-human IL-6 receptor alpha monoclonal antibody that blocks the signaling originated by the IL-6/IL-6R complex like tocilizumab,is an effective treatment. However, predictors of the response to sarilumab are still required.Objectives:We aimed to combine IL-6, soluble IL-6R (sIL-6R) and gp130 (sgp130) levels to identify groups of sarilumab responses.Methods:This research is a retrospective study. a total of 32 RA patients with SRL therapy in our department from February 1 in 2018 to December 31 in 2019 were included. Serum and clinical data from 32 RA patients were collected before treatment and until the last visit. Follow-up period was up to one year after starting SRL treatment. Serum were tested for IL-6 (Human IL-6 Quantikine ELISA Kit, R&D systems), sIL-6R (Human soluble IL-6R alpha Quantikine ELISA Kit, R&D systems) and sgp130 (Human soluble gp130 Quantikine ELISA Kit, R&D systems), using specific ELISAs according to the manufacturer’s instructions. Hierarchical cluster analysis (JMP14.3.0) was used to establish the relationship between IL-6, sIL-6R and sgp130. We evaluated the efficacy of SRL treatment on the last visit using European League Against Rheumatism (EULAR) response criteria in the groups of patients. The other statistical analyses were performed with EZR 1.41, and p Values less than 0.05 were considered significant.Results:The median age of patients was 70.5 (IQR: 66.5-74.3) years and the median of disease duration was 7.3 (1.7-15.3) years. Nine (28.1%) patients were biologics and Jakinibs naive. the median follow-up periods were 24 (12-26) weeks. The baseline DAS28 was median 4.39 (3.77 - 5.43), and CDAI was 21.1 (11.7-29.5). When comparing responders and non-responders, there were no significant differences in any of the baseline parameters and cytokines. Four statistical significant clusters of RA patients (i.e., Group1, Group2, Group3 and tocilizumab use group before SRL) were defined by serum concentrations of IL-6, sIL-6R and spg130 at baseline. The levels of IL-6 expressed as median in Group1 patients were 25.6 (14.4–72.2) pg/ml, in Group2 5.9 (3.3–11.3) pg/ml, and in Group3 70.2 (45.4–86.1) pg/ml (p < 0.002, significant difference only between Group2 and Group3). The levels of sIL-6R expressed as median in Group1 patients were 38.7 (34.7-45.1) ng/ml, in Group2 35.1 (24.8-41.9) ng/ml, and in Group3 35.7 (34.2-39.8) ng/ml (p = 0.5477). The levels of sgp130 expressed as median in Group1 patients were 272.6 (263.0-277.2) ng/ml, in Group2 223.1 (221.0-228.0) ng/ml, and in Group3 204.6 (192.0-207.6) ng/ml (p < 0.00003, significant difference between the three groups respectively). There were no significant differences in any of the baseline clinical features and laboratory findings between the three groups. Out of the 8 patients in Group1 had a good or moderate response to SRL. Conversely, the percentage of patients with no response to SRL was higher in Group3 than in Group1 and Group2.Conclusion:RA patients could be easily stratified prior to the rapeutic intervention with sgp130 related to the IL-6 signal reguration. Group1 patients, who had the best response to SRL, had the highest level of sgp130.Table 1.Comparison of baseline serum IL-6, sIL-6R and sgp130 of each groups of patientsTCZ use before SRLGroup 1Group 2Group 3P valuen=3N=9N=8N=9IL-6,pg/mL69.8,77.6,592.6Median[IQR]25.6[14.4-72.2]5.9[3.3-11.3]70.2[45.4-86.1]<0.002csIL-6R,ng/mL390.5,413.2,481.7Median[IQR]38.7[34.7-45.1]35.1[24.8-41.9]35.7[34.2-39.8]0.547sgp130,ng/mL205.6,219.2,239.8Median[IQR]273[263-277]223[221-228]205[192-208]<0.001abc*a, b and c mean that statically significant difference between subgroups as a: group1 vs. 2, b: group 1 vs. 3, c: group 2 vs. 3.Disclosure of Interests:Takahiro Yoshikawa: None declared, Tetsuya Furukawa: None declared, Masao Tamura: None declared, Teppei Hashimoto: None declared, Mai Morimoto: None declared, Naoto Azuma: None declared, Kiyoshi Matsui Grant/research support from: Asahi Kasei Pharma, Astellas Pharma (research grants), Speakers bureau: Bristol-Myers Squibb (lecture fees)

Trans IL-6 signaling does not appear to play a role in renal scarring after urinary tract infection

While inflammation is an important innate defense mechanism against infection, it can also lead to local tissue damage. The trans signaling pathway of interleukin (IL)-6 is a known mediator of inflammation. We hypothesized that the trans IL-6 signaling pathway is associated with the development of post febrile urinary tract infection (UTI) renal scarring. To compare soluble regulators of trans IL-6 signaling between patients with a history of febrile UTI who do or do not have renal scarring. After IRB-approval, we collected urine samples in pediatric patients with a history of febrile (≥38°C) UTI (urine culture >50K uropathogen) with documented presence or absence of renal scarring on imaging. Samples were collected at a time when patients were not actively infected. Enzyme-linked immunosorbent assays were performed on samples for markers of trans IL-6 signaling: IL-6, soluble (s) IL-6 receptor (R), and soluble (s)gp130, a buffer in trans IL-6 signaling. Values were normalized to urine creatinine. Results were analyzed by t-test or Mann-Whitney U. Spearman rank correlation was used. A p-value of <0.05 was considered significant. A total of 50 urines from patients with a history of febrile UTI were collected: 23 with and 27 without scarring. There was no difference between groups regarding age or gender. There was no significant difference in urine IL-6, sIL-6R, or sgp130 between those with and without scarring (Figure). While IL-6 values significantly correlated with sIL-6R and sgp130 in those without renal scarring, IL-6 did not correlate with sgp130 in those with scarring. Ratios of IL-6 to sgp130 and sIL-6R to sgp130 were not different between groups. The inflammatory response generated in response to infection is believed to be largely responsible for the development of renal scarring after UTI. IL-6 is a cytokine known to be induced during UTI with a pro-inflammatory pathway, known as trans signaling. This study investigated for differences in markers of trans IL-6 signaling between patients with a history of febrile UTI with and without renal scarring. There was no significant difference between the absolute values or ratio of these markers between groups. Markers of trans IL-6 signaling are not different between individuals with a history of febrile UTI with and without renal scarring in the non-acute setting.

慢性硬膜下血腫におけるsoluble interleukin-6 receptorとsoluble gp130の発現について

慢性硬膜下血腫におけるsoluble interleukin-6 receptorとsoluble gp130の発現について

Dual role of IL6 mediated by mesenchymal stromal cell signaling to joint macrophages in osteoarthritis

Purpose: Osteoarthritis (OA) is a joint disease affecting > 5 million Canadians and patients have limited palliative and joint-replacement surgical options. Stromal cell therapy is emerging as a compelling treatment for OA. Our group led the first-in-Canada Ph1/2 trial with bone marrow mesenchymal stromal cells (BM-MSCs) in OA patients successfully; and significant improvements in patient outcomes were observed. This was accompanied with reduction in pro-inflammatory monocytes/macrophages (MΦs) in the synovial fluid (SF), suggestive of a clinical MSC anti-inflammatory effect. Understanding mechanism of action of MSCs in OA will enable effective donor MSC screening, and generation of more efficient engineered MSCs. While IL6 is a known pro-inflammatory mediator in the joint, and anti-IL6 therapeutics have been effective in treatment of Rheumatoid Arthritis, blocking single pro-inflammatory cytokines has been less effective in OA. This leads us to believe that IL6 might have complex roles. Indeed, MSCs-induced polarization of macrophages to inflammation resolving subtypes via IL6 signaling. This effect is not well studied in an OA joint where high levels of IL6 may have pro-inflammatory effects. We hypothesize that IL-6, which is known as pro-inflammatory mediator in OA is mediating anti-inflammatory function of MSCs through signaling via membrane-bound, but not soluble receptors. Methods: We co-cultured peripheral blood-derived MΦs with OA BM-MSCs in the presence of early and late SF from OA patients; or in the presence of IL6 antibody. Polarization of MΦs were assessed by analysis of surface markers and IL10 secretion. Levels of IL6 soluble IL6 receptor (sIL6R) were measured by ELISA. Results: Preliminary quantification of BM- MSC from OA patients revealed high IL6 secretion is associated with positive patient-reported outcomes. IL6 antibody abrogated MSCs-induced anti-inflammatory polarization of MΦs as shown by reduction of CD163 and CD206, suggesting a key role for IL6 in MSC anti-inflammatory effects on MΦs. Paradoxically, IL6 levels were increased in SF from late stage OA, whereas levels of sIL6R were comparable in early and late OA-SF. Further, the effect of MSCs on anti-inflammatory polarization of MΦs was attenuated in the presence of late OA-SF compared to early OA-SF. This could be due to enhanced IL6 trans-signaling (mediated by sIL6R) in late-stage OA SF expected to occur at the expense of reduced IL6 classical pathway (mediated by membrane bound IL6 receptor, mIL6R). To discriminate between classical vs. trans-signalling, we are using soluble gp130, a non-signaling decoy receptor which complexes IL6-sIL6R. Our preliminary result showed that sgp130 treatment enhanced the expression of CD163 in MΦs exposed to pooled OA SF. The classical IL6 pathway will be studied specifically by silencing mIL6R in MΦs using siRNA Conclusions: MSCs exert their anti-inflammatory action in OA, at least partly through polarization of MΦs to anti-inflammatory phenotype mediated by IL6. The ratio of IL6 signaling through trans-vs. classical signaling pathways is an important arbiter of MSC-modulation of joint inflammation.

Estrogen downregulates gp130 expression in HUVECs by regulating ADAM10 and ADAM17 via the estrogen receptor

Glycoprotein130 (gp130) is an important signal transducer in the interleukin-6 (IL-6) trans-signaling pathway, which plays a crucial role in chronic inflammation in atherosclerosis. Studies suggest that estrogen can inhibit IL-6/gp130 signaling and reduce the risk of coronary artery disease, but the precise mechanism is unclear. The aim of this study was to investigate whether and how estrogen regulates gp130 in human umbilical vein endothelial cells (HUVECs). HUVECs were first treated with IL-6 and soluble IL-6 receptor (sIL-6R) to induce inflammation, then treated with estradiol. We then measured the expression of gp130, a disintegrin and metalloproteinase 10 (ADAM10) and 17 (ADAM17) by RT-PCR and western blot. Levels of soluble gp130 (sgp130) in the culture supernatant were measured by ELISA. We found that IL-6 and sIL-6R increased expression of gp130 protein and decreased levels of sgp130 protein, without affecting gp130 mRNA levels. Estradiol treatment reversed these effects in a concentration- and time-dependent manner. These effects were regulated by ADAM10 and ADAM17 via an estrogen receptor α/β-dependent mechanism. These results shed further light on the mechanism underlying the clinical effects of estrogen therapy in atherosclerosis and coronary artery disease.

Analysis of the genetic variants associated with circulating levels of sgp130. Results from the IMPROVE study

The genes regulating circulating levels of soluble gp130 (sgp130), the antagonist of the inflammatory response in atherosclerosis driven by interleukin 6, are largely unknown. Aims of the present study were to identify genetic loci associated with circulating sgp130 and to explore the potential association between variants associated with sgp130 and markers of subclinical atherosclerosis. The study is based on IMPROVE (n = 3703), a cardiovascular multicentre study designed to investigate the determinants of carotid intima media thickness, a measure of subclinical atherosclerosis. Genomic DNA was genotyped by the CardioMetaboChip and ImmunoChip. About 360,842 SNPs were tested for association with log-transformed sgp130, using linear regression adjusted for age, gender, and population stratification using PLINK v1.07. A p value of 1 × 10−5 was chosen as threshold for significance value. In an exploratory analysis, SNPs associated with sgp130 were tested for association with c-IMT measures. We identified two SNPs significantly associated with sgp130 levels and 24 showing suggestive association with sgp130 levels. One SNP (rs17688225) on chromosome 14 was positively associated with sgp130 serum levels (β = 0.03 SE = 0.007, p = 4.77 × 10−5) and inversely associated with c-IMT (c-IMTmean–maxβ = −0.001 SE = 0.005, p = 0.0342). Our data indicate that multiple loci regulate sgp130 levels and suggest a possible common pathway between sgp130 and c-IMT measures.

Soluble interleukin-6 receptor in young adults and its relationship with body composition and autonomic nervous system.

BackgroundThe immune system generates inflammatory responses through cytokines like Interleukin 6 (IL‐6) and the Tumor Necrosis Factor alpha (TNF α); these cytokines mediate cellular responses aided by the presence of soluble receptors such as: Soluble Interleukin 6 Receptor (sIL6R) and Soluble Tumor Necrosis Factor Receptors Type 1 and 2 (sTNFR1, sTNFR2); the literature is limited about the relationship between this cytokines and the role of its soluble receptors.ObjectivesThis study is to determine a possible relationship between specific inflammatory markers and their soluble receptors with the autonomic nervous system's activity and body composition.Methods27 subjects (13 men of 19.3 ± 1.6 years old and 14 women of 19.1 ± 1.7 years old) were evaluated. Body composition, autonomic nervous system activity and plasma concentration of inflammatory markers IL‐6, TNF α, sIL6R, sTNFR1 and sTNFR2 were measured using bio‐impedance, heart rate variability and ELISA respectively.ResultsA positive association between body‐fat percentage and the sIL6R (0.47, p = .013) as well as inverse relationship between muscular mass and the sIL6R (−0.45, p = .019) were found. The sIL6R was also positively correlated with sympathetic activity markers: Relation LF/HF (0.52, p = .006), cardiac sympathetic index (0.45, p = .008), and cardiac vagal index (−0.44, p = .022).ConclusionThis study suggested that the IL‐6 trans‐signaling involving both the soluble receptor, sIL6R, and gp130 membrane co‐receptor could produce inflammatory responses that generate an impact on the autonomic nervous system, possibly due to its direct action on the hypothalamus, the solitary tract nucleus, or the heart.

The IL-6-neutralizing sIL-6R-sgp130 buffer system is disturbed in patients with type 2 diabetes.

Serum levels of interleukin-6 (IL-6) are increased in patients with type 2 diabetes (T2D). IL-6 exerts its pleiotropic effects via the IL-6 α-receptor (IL-6R), which exists in membrane-bound and soluble (sIL-6R) forms and activates cells via the β-receptor glycoprotein 130 (gp130). The nonsynonymous single-nucleotide polymorphism (SNP) rs2228145 (Asp358Ala) within the IL6R locus is associated with T2D. The aim of this study was to determine whether sIL-6R in combination with soluble gp130 (sgp130) is able to form an IL-6-neutralizing buffer in healthy subjects and whether this is disturbed in T2D. We found that sIL-6R-sgp130 indeed forms an IL-6-neutralizing buffer in the serum of healthy humans, whose capacity is controlled by the SNP of the IL-6R. Circulating sIL-6R-sgp130 levels were lower in T2D subjects (P < 0.001), whereas IL-6 was high and inversely correlated with sIL-6R (r = -0.57, P < 0.001), indicating a severe disturbance of the buffer. This phenomenon is also observed in sex- and age-matched patients with both T2D and atherosclerosis but not in patients with atherosclerosis alone. In conclusion, sIL-6R and sgp130 serum levels were significantly lower in T2D patients compared with healthy subjects or atherosclerosis patients, although IL-6 levels were high. These data suggest that disturbance of the protective buffer may be closely associated with T2D pathophysiology.

Dual role of IL6 mediated by mesenchymal stromal cell signaling to joint macrophages in osteoarthritis

Background & Aim Osteoarthritis (OA) is a joint disease affecting> 5 million Canadians and patients have limited palliative and joint-replacement surgical options. Stromal cell therapy is emerging as a compelling treatment for OA. Our first-in-Canada Ph1/2 trial with bone marrow mesenchymal stromal cells (BM-MSCs) in OA patients showed significant improvements in patient outcomes. Levels of pro-inflammatory monocytes/macrophages (MΦs) were reduced in the synovial fluid (SF), suggestive of a clinical MSC anti-inflammatory action. Understanding mechanism of action of MSCs in OA will enable effective donor MSC screening, and generation of more efficient engineered MSCs. While IL6 is a known pro-inflammatory mediator in the joint, blocking IL6 has not been so effective in OA suggesting complex roles for IL6. Indeed, MSCs induced homeostatic polarization of macrophages via IL6. This effect is not well studied in an OA joint where high levels of IL6 may have pro-inflammatory roles. We hypothesize that IL-6 mediates anti-inflammatory function of MSCs via IL6 membrane-bound receptor (mIL6R), but not soluble IL6 receptors (sIL6R). Methods, Results & Conclusion We co-cultured blood-derived MΦs with OA-MSCs in the presence of SF from OA patients; or in the presence of IL6 antibody. Polarization of MΦs were assessed by analysis of surface markers. Levels of IL10, IL6 and sIL6R were measured by ELISA. Preliminary analysis of IL6 from MSC from OA patients revealed high IL6 secretion is associated with positive patient-reported outcomes. IL6 antibody abrogated MSCs-induced homeostatic polarization of MΦs, suggesting a key role for IL6 in MSC anti-inflammatory effects. Paradoxically, IL6 levels were increased in SF from late stage OA, whereas sIL6R levels were comparable in early and late OA-SF. Further, the effect of MSCs on MΦs polarization was attenuated in the presence of late OA-SF compared to early OA-SF. This could be due to enhanced IL6 trans-signaling (via sIL6R) in late-OA SF expected to occur at the expense of reduced IL6 classical pathway (via mIL6R). To discriminate between classical vs. trans-signalling, we are using soluble gp130, a non-signaling decoy receptor which complexes IL6-sIL6R without affecting the classical pathway. In conclusion, MSCs exert their anti-inflammatory action in OA, at least partly via polarization of MΦs to homeostatic phenotype mediated by IL6. The ratio of IL6 signaling through trans-vs. classical pathways is an important arbiter of MSC-modulation of joint inflammation.

Soluble gp130 prevents interleukin-6 and interleukin-11 cluster signaling but not intracellular autocrine responses.

Interleukin-6 (IL-6) is a proinflammatory cytokine of the IL-6 family, members of which signal through a complex of a cytokine-specific receptor and the signal-transducing subunit gp130. The interaction of IL-6 with the membrane-bound IL-6 receptor (IL-6R) and gp130 stimulates "classic signaling," whereas the binding of IL-6 and a soluble version of the IL-6R to gp130 stimulates "trans-signaling." Alternatively, "cluster signaling" occurs when membrane-bound IL-6:IL-6R complexes on transmitter cells activate gp130 receptors on neighboring receiver cells. The soluble form of gp130 (sgp130) is a selective trans-signaling inhibitor, but it does not affect classic signaling. We demonstrated that the interaction of soluble gp130 with natural and synthetic membrane-bound IL-6:IL-6R complexes inhibited IL-6 cluster signaling. Similarly, IL-11 cluster signaling through the IL-11R to gp130 was also inhibited by soluble gp130. However, autocrine classic and trans-signaling was not inhibited by extracellular inhibitors such as sgp130 or gp130 antibodies. Together, our results suggest that autocrine IL-6 signaling may occur intracellularly.

Naringenin Modifies the Development of Lineage-Specific Effector CD4+ T Cells.

Disrupted balance in the lineages of CD4+ T cell subsets, including pro-inflammatory T helper (Th) cells and anti-inflammatory regulatory T cells (Treg), is a primary pathogenic factor for developing autoimmunity. We have found that this immunomodulatory effect of naringenin on effector T cells and T-cell mediated experimental autoimmune encephalomyelitis (EAE). We therefore explored the effects of naringenin on the development of different effector CD4+ T cells. Naïve CD4+ T cells were differentiated under respective Th1, Th2, Th17, and Treg polarizing conditions with naringenin. Percent populations of each differentiated CD4+ T cell subsets were determined and the corresponding regulating pathways were investigated as underlying mechanisms. Naringenin mainly inhibited CD4+ T cell proliferation and differentiation to Th1 and Th17, but did not affect Th2 cells. Impeded Th1 polarization was associated with inhibition of its specific regulator proteins T-bet, p-STAT1, and p-STAT4 by naringenin. Likewise, Th17 regulator proteins RORγt, p-STAT3, and Ac-STAT3 were also inhibited by naringenin. In addition, naringenin promoted Treg polarization and also prevented IL-6-induced suppression of Treg development via down-regulation of p-Smad2/3 as well as inhibition of IL-6 signaling, and the latter was further supported by the in vivo results showing lower soluble IL-6R but higher soluble gp130 levels in plasma of naringenin-fed compared to the control EAE mice. Naringenin impacts CD4+ T cell differentiation in a manner that would explain its beneficial effect in preventing/mitigating T cell-mediated autoimmunity.

Inhibition of interleukin-6 trans-signaling prevents inflammation and endothelial barrier disruption in retinal endothelial cells

Vascular inflammation plays a critical role in the pathogenesis of diabetic retinopathy. Recently, Interleukin-6 (IL-6) trans-signaling via soluble IL-6 receptor (sIL-6R) has emerged as a prominent regulator of inflammation in endothelial cells. This study was designed to test the hypothesis that selective inhibition of the IL-6 trans-signaling pathway will attenuate inflammation and subsequent barrier disruption in retinal endothelial cells. Human retinal endothelial cells (HRECs) were exposed to IL-6 and sIL-6R to induce IL-6 trans-signaling and the commercially available compound sgp130Fc (soluble gp-130 fused chimera) was used to selectively inhibit IL-6 trans-signaling. IL-6 trans-signaling activation caused a significant increase in STAT3 phosphorylation, expression of adhesion molecules, ROS production and apoptosis in HRECs whereas a significant decrease in mitochondrial membrane potential and NO production was observed in IL-6 trans-signaling activated cells. These changes were not observed in cells pre-treated with sgp130Fc. IL-6 trans-signaling activation was sufficient to cause barrier disruption in endothelial monolayers and pre-treatment of HRECs with sgp130Fc, maintained endothelial barrier function similar to that of untreated cells. Thus, in conclusion, these results indicate that IL-6 trans-signaling is an important mediator of inflammation, apoptosis and barrier disruptive effects in the retinal endothelial cells and inhibition of the IL-6 trans-signaling pathway using sgp130-Fc attenuates vascular inflammation and endothelial barrier disruption.

The balance of interleukin (IL)-6, IL-6·soluble IL-6 receptor (sIL-6R), and IL-6·sIL-6R·sgp130 complexes allows simultaneous classic and trans-signaling

Interleukin (IL-)6 is the major pro-inflammatory cytokine within the IL-6 family. IL-6 signals via glycoprotein 130 (gp130) and the membrane-bound or soluble IL-6 receptor (IL-6R), referred to as classic or trans-signaling, respectively. Whereas inflammation triggers IL-6 expression, eventually rising to nanogram/ml serum levels, soluble IL-6R (sIL-6R) and soluble gp130 (sgp130) are constitutively present in the upper nanogram/ml range. Calculations based on intermolecular affinities have suggested that systemic IL-6 is immediately trapped in IL-6·sIL-6R and IL-6·sIL-6R·sgp130 complexes, indicating that sIL-6R and sgp130 constitute a buffer system that increases the serum half-life of IL-6 or restricts systemic IL-6 signaling. However, this scenario has not been experimentally validated. Here, we quantified IL-6·sIL-6R and IL-6·sIL-6R·sgp130 complexes over a wide concentration range. The amounts of IL-6 used in this study reflect concentrations found during active inflammatory events. Our results indicated that most IL-6 is free and not complexed with sIL-6R or sgp130, indicating that the level of endogenous sgp130 in the bloodstream is not sufficient to block IL-6 trans-signaling via sIL-6R. Importantly, addition of the single-domain antibody VHH6, which specifically stabilizes IL-6·sIL-6R complexes but did not bind to IL-6 or sIL-6R alone, drove free IL-6 into IL-6·sIL-6R complexes and boosted trans-signaling but not classic signaling, demonstrating that endogenous sIL-6R has at least the potential to form complexes with IL-6. Our findings indicate that even though high concentrations of sIL-6R and sgp130 are present in human serum, the relative ratio of free IL-6 to IL-6·sIL-6R allows for simultaneous classic and trans-signaling.

Soluble glycoprotein 130 is inversely related to severity of coronary atherosclerosis

Purpose: Recent studies indicate that the effects of interleukin 6 (IL-6) realized via soluble IL-6 receptor (sIL-6R) facilitate the development of various pathological processes. Soluble gp130 (sgp130) is a naturally occurring inhibitor of signal transduction via this pathway. In this study, we assessed the relationship between circulating levels of IL-6, sIL-6R and sgp130 and severity of coronary atherosclerosis in patients with stable coronary artery disease (CAD).Methods: Plasma levels of IL-6, sIL-6R and sgp130 were measured in patients with atherosclerotic coronary lesions (n = 128, group 1) and with intact coronary arteries (n = 48, group 2). The severity of coronary atherosclerosis was evaluated by the number of affected arteries and by Gensini Score index.Results: Circulating IL-6 levels in group 1 were significantly higher than those in group 2. The levels of sIL-6R did not differ considerably in both the groups. The levels of sgp130 in group 1 were significantly lower than in group 2. A negative correlation has been revealed between sgp130 levels and the number of affected coronary arteries and Gensini Score index.Conclusions: Serum concentration of sgp130 in patients with stable CAD is inversely related to severity of coronary damage. Low sgp130 level may serve as an additional indicator of coronary atherosclerosis severity.

Frontline Science: Proliferation of Ly6C+ monocytes during urinary tract infections is regulated by IL-6 trans-signaling.

Ly6C+ monocytes are important components of the innate immune defense against infections. These cells have been shown to proliferate in the bone marrow of mice with systemic infections. However, the proliferative capacity of Ly6C+ monocytes in infected peripheral tissues as well as the associated regulatory mechanisms remain unclear. In this study, we analyzed the proliferative capacity of Ly6C+ monocytes in the urinary bladder after infection with uropathogenic E. coli, one of the most prevalent pathogen worldwide, and in LPS-induced peritonitis. We show that Ly6C+ monocytes proliferated in the bladder after infection with uropathogenic E. coli and in the peritoneum after intraperitoneal injection of LPS. We identified IL-6, a molecule that is highly expressed in infections, as a crucial regulator of Ly6C+ monocyte proliferation. Inhibition of IL-6 via administration of antibodies against IL-6 or gp130 impeded Ly6C+ monocyte proliferation. Furthermore, repression of IL-6 trans-signaling via administration of soluble gp130 markedly reduced the proliferation of Ly6C+ monocytes. Overall, this study describes the proliferation of Ly6C+ monocytes using models of urinary tract infection and LPS-induced peritonitis. IL-6 trans-signaling was identified as the regulator of Ly6C+ monocyte proliferation.

Epstein-Barr virus-induced gene 3 (EBI3) can mediate IL-6 trans-signaling

Epstein-Barr virus-induced gene 3 (EBI3) is a subunit of the composite cytokines IL-27 and IL-35. Both have beneficial functions or effects in models of infectious and autoimmune diseases. This suggests that administration of EBI3 could be therapeutically useful by binding free p28 and p35 to generate IL-27 and IL-35. IL-27- and IL-35-independent functions of EBI3 could compromise its therapeutic uses. We therefore assessed the effects of EBI3 on cytokine receptor-expressing cells. We observed that EBI3 activates STAT3 and induces the proliferation of the IL-6-dependent B9 mouse plasmacytoma cell line. Analyses using blocking mAbs and Ba/F3 transfectants expressing gp130 indicate that EBI3 activity was linked to its capacity to mediate IL-6 trans-signaling, albeit less efficiently than soluble IL-6Rα. In line with this interpretation, co-immunoprecipitation and SPR experiments indicated that EBI3 binds IL-6. An important pro-inflammatory function of IL-6 trans-signaling is to activate blood vessel endothelial cells. We observed that EBI3 in combination with IL-6 could induce the expression of chemokines by human venal endothelial cells. Our results indicate that EBI3 can promote pro-inflammatory IL-6 functions by mediating trans-signaling. These unexpected observations suggest that use of EBI3 as a therapeutic biologic for autoimmune diseases will likely require co-administration of soluble gp130 to prevent the side effects associated with IL-6 trans-signaling. Together with previous studies that demonstrated activation of IL-6R by p28 (IL-30), new findings further suggest a complex interrelation between IL-27 and IL-6.

Inhibitory Mechanism of the Outer Membrane Growth of Chronic Subdural Hematomas.

We previously demonstrated that the inflammatory cytokine interleukin-6 (IL-6) activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway in fibroblasts within the outer membranes of chronic subdural hematomas (CSDHs), and the activation of this pathway may induce CSDH outer membrane growth. The inhibitory system for this signal transduction pathway is unknown. CSDH fluids were obtained from 10 patients during trepanation surgery as the case group, and cerebrospinal fluid (CSF) samples were obtained from seven patients suffering from subarachnoid hemorrhage (SAH) on Day 1 as the control group. The concentrations of IL-6, soluble IL-6 receptor (sIL-6R), and soluble gp130 (sgp130) in CSDH fluid and CSF were measured using enzyme immunoassay kits. The co-localization of IL-6 and sgp130 in CSDH fluid was examined by immunoprecipitation. The expression levels of STAT3, JAK2, suppressor of cytokine signaling 3 (SOCS3), and protein inhibitor of activated Stat3 (PIAS3) in the outer membranes of CSDHs were examined by immunostaining. Soluble IL-6R and sgp130 concentrations in CSDH fluid were significantly higher than those in CSF after SAH. Sgp130 and IL-6 were co-immunoprecipitated from CSDH fluid. Immunostaining revealed STAT3, JAK2, SOCS3, and PIAS3 expression in fibroblasts located in the outer membranes of CSDHs. Soluble gp130 binds to IL-6/sIL-6R and acts as an antagonist of the JAK/STAT signaling pathway. SOCS3 also binds to JAK and inhibits its signaling pathway. In addition, PIAS3 regulates STAT3 activation. These factors might down-regulate the IL-6/JAK/STAT signaling pathway in fibroblasts within CSDH outer membranes. Therefore, these molecules may be novel therapeutic targets for the inhibition of CSDH growth.