BackgroundInterleukin-37 (IL-37), a new member of IL-1 family cytokine, is recently identified as a natural inhibitor of innate immunity. This study aimed to measure the peripheral blood mononuclear cells (PBMCs) and serum levels of IL-37 in patients with systemic lupus erythematosus (SLE) and to investigate its role in SLE, including its correlation with disease activity, organ disorder and the regulation of inflammatory cytokines.MethodsThe expressions of IL-37 mRNAs in PBMCs and serum IL-37 levels in 66 SLE patients were measured by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). SLE patients PBMCs were stimulated with recombinant IL-37, levels of cytokines TNF-α, IL-1β, IL-6 and IL-10 were detected by RT-PCR and ELISA.ResultsIL-37 mRNAs and serum protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease showed higher IL-37 mRNAs and serum protein levels compared with those with inactive disease as well as healthy controls. Serum IL-37 levels correlated with SLEDAI and inversely with C3 and C4. Serum IL-37 levels were higher in SLE patients with renal involvement compared with those without renal disease. In vitro, IL-37 inhibited the production of TNF-α, IL-1β and IL-6 in PBMCs of patients with SLE, whereas the production of IL-10 was unaffected.ConclusionsIL-37 associated with SLE disease activity, especially related with SLE renal disease activity. IL-37 is an important cytokine in the control of SLE pathogenesis by suppressing the production of inflammatory cytokines. Thus, IL-37 may provide a novel research target for the pathogenesis and therapy of SLE.

IL-37, a new member of the IL-1 cytokine family, is a natural inhibitor of innate immunity associated with autoimmune diseases. This study was undertaken to evaluate whether IL-37 has antiarthritic effects in patients with rheumatoid arthritis (RA) and in mice with collagen-induced arthritis (CIA). In this study, we analyzed the expression of IL-37 in PBMCs, serum, and lymphocytes from RA patients as well as CD4+ T cells polarized under Th1/Th2/Th17 conditions. The role of IL-37 was assessed by investigating the effects of recombinant human (rh)IL-37 and an adenovirus encoding human IL-37 (Ad–IL-37) on Th17 cells and Th17-related cytokines in RA patients and CIA mice. We found that active RA patients showed higher IL-37 levels compared with patients with inactive RA and healthy controls. Upregulated IL-37 expression also was found in CD3+ T cells and CD4+ T cells from RA patients and in Th1/Th17-differentiation conditions. rhIL-37 markedly decreased IL-17 expression and Th17 cell frequency in PBMCs and CD4+ T cells from RA patients. Furthermore, IL-37 exerted a more suppressive effect on Th17 cell proliferation, whereas it had little or no effect on Th17 cell differentiation. IL-17 and IL-17–driving cytokine production were significantly reduced in synovium and joint cells from CIA mice receiving injections of Ad–IL-37. Our findings indicate that IL-37 plays a potent immunosuppressive role in the pathogenesis of human RA and CIA models via the downregulation of IL-17 and IL-17–triggering cytokine production and the curbing of Th17 cell proliferation.

IntroductionOur objective in the present study was to determine the signaling pathway of interleukin 10 (IL-10) for modulating IL-17 expression in macrophages and the importance of this mediation in collagen-induced arthritis (CIA).MethodsIL-10-knockout (IL-10−/−) mice and wild-type (WT) mice were immunized with chicken type II collagen (CII) to induce arthritis. The expression levels of IL-17 and retinoid-related orphan receptor γt (RORγt) in macrophages and joint tissues of IL-10−/− and WT mice were analyzed by enzyme-linked immunosorbent assay, quantitative RT-PCR (qRT-PCR) and Western blotting. The F4/80 macrophages and positive IL-17-producing macrophages in synovial tissues of the mice were determined by immunohistochemistry. The populations of classically activated macrophage (M1) and alternatively activated macrophage (M2) phenotypes were analyzed by flow cytometry. The expression of genes associated with M1 and M2 markers was analyzed by qRT-PCR.ResultsCompared to WT mice, IL-10−/− mice had exacerbated CIA development, which was associated with increased production of T helper 17 cell (Th17)/Th1 proinflammatory cytokines and CII-specific immunoglobulin G2a antibody after CII immunization. Macrophages in IL-10−/− mice had increased amounts of IL-17 and RORγt compared with the amounts in WT mice with CIA. Immunofluorescence microscopy showed that the number of IL-17-producing macrophages in synovial tissues was significantly higher in IL-10−/− mice than in WT mice. IL-10 deficiency might promote macrophage polarization toward the proinflammatory M1 phenotype, which contributes to the rheumatoid arthritis inflammation response.ConclusionIL-10 inhibits IL-17 and RORγt expression in macrophages and suppresses macrophages toward the proinflammatory M1 phenotype, which is important for the role of IL-10 in mediating the pathogenesis of CIA.

IL-10 is an immunosuppressive cytokine produced and sensed by many immune cells and exerts a protective role in autoimmune diseases. However, the underlying mechanism by which IL-10 contributes to prevent the arthritic inflammation in macrophages is poorly understood. Herein we report on a novel anti-arthritic property of IL-10 through the inhibition of IL-33 signaling by macrophages during collagen-induced arthritis (CIA) development. We show that IL-33 expression rather than its receptor (ST2) is positively correlated with IL-10 level in active RA. IL-10 deficiency in mice leads to significant upregulation of IL-33 expression and aggravates the progression of CIA, while exogenous IL-10 treatment effectively diminishes IL-33 production in IL-10 knockout (IL-10−/−) CIA mice. We demonstrate further that the inhibitory effect of IL-10 in suppressing IL-33 production requires STAT3 activation in macrophages. Furthermore, IL-33 stimulated proinflammatory genes are notably increased in IL-10−/− CIA mice, whereas macrophages treated with recombinant IL-10 exhibit decreased IL-33 amplified inflammation and inhibited IL-33 activated NF-κB signaling pathway. Our findings indicate that IL-10 act as a negative regulator of IL-33/ST2 signaling pathways in vivo, suggesting a potential therapeutic role of IL-10 in autoimmune diseases.

To gain further insights into the molecular basis of Sulforaphane (SF) mediated retinal pigment epithelial (RPE) 19 cell against oxidative stress, we investigated the effects of SF on the regulation of gene expression on a global scale and tested whether SF can endow RPE cells with the ability to resist apoptosis. The data revealed that after exposure to H2O2, RPE 19 cell viability was increased in the cells pretreated with SF compared to the cell not treated with SF. Microarray analysis revealed significant changes in the expression of 69 genes in RPE 19 cells after 6 hours of SF treatment. Based on the functional relevance, eight of the SF-responsive genes, that belong to antioxidant redox system, and inflammatory responsive factors were validated. The up-regulating translation of thioredoxin-1 (Trx1) and the nuclear translocation of Nuclear factor-like2 (Nrf2) were demonstrated by immunoblot analysis in SF treated RPE cells. Our data indicate that SF increases the ability of RPE 19 cell against oxidative stress through up-regulating antioxidative enzymes and down-regulating inflammatory mediators and chemokines. The results suggest that the antioxidant, SF, may be a valuable supplement for preventing and retarding the development of Age Related Macular Degeneration.