Recent studies indicate that high-mobility group box protein 1 (HMGB1) contributes to the pathogenesis of diverse autoimmune disorders. It induces the production of interferon-alpha (IFN-alpha) and tumor necrosis factor alpha (TNF-alpha) in vitro. In the present study, plasma HMGB1, TNF-alpha, and IFN-alpha were determined with ELISA in 37 patients with systemic lupus erythematosus (SLE) and 39 age- and sex-matched healthy controls (HC). The possible associations of these cytokines with disease activities, autoantibodies, and certain laboratory parameters were also explored. The plasma levels of HMGB1, TNF-alpha, and IFN-alpha were increased in SLE patients compared with those of HC (P < 0.05). Moreover, the levels of HMGB1 and TNF-alpha in the active SLE patients were elevated compared with those in inactive patients and HC. Additionally, plasma HMGB1 was positively correlated with peripheral neutrophils, and plasma TNF-alpha was positively correlated with anti-Sm, ESR and CRP, while plasma IFN-alpha was inversely correlated with the age and platelet level in SLE patients. Our data indicated that increased plasma HMGB1 was associated with disease activity in SLE, which was similar to TNF-alpha. High level of plasma IFN-alpha may be related to nephritis and thrombocytopenia in SLE.

IntroductionSystemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems. Previous studies have suggested that interferon-lambda 1 (IFN-λ1), a type III interferon, plays an immunomodulatory role. In this study we investigated its role in SLE, including its correlation with disease activity, organ disorder and production of chemokines.MethodsWe determined levels of IFN-λ1 mRNA in peripheral blood mononuclear cells (PBMC) and serum protein levels in patients with SLE using real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunoassay (ELISA). Further, we detected the concentration of IFN-inducible protein-10 (IP-10), monokine induced by IFN-γ (MIG) and interleukin-8 (IL-8) secreted by PBMC under the stimulation of IFN-λ1 using ELISA.ResultsIFN-λ1 mRNA and serum protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease showed higher IFN-λ1 mRNA and serum protein levels compared with those with inactive disease as well. Serum IFN-λ1 levels were positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), anti-dsDNA antibody, C-reactive protein (CRP) and negatively correlated with complement 3. Serum IFN-λ1 levels were higher in SLE patients with renal involvement and arthritis compared with patients without the above-mentioned manifestations. IFN-λ1 with different concentrations displayed different effects on the secretion of the chemokines IP-10, MIG and IL-8.ConclusionsThese findings indicate that IFN-λ1 is probably involved in the renal disorder and arthritis progression of SLE and associated with disease activity. Moreover, it probably plays an important role in the pathogenesis of SLE by stimulating secretion of the chemokines IP-10, MIG and IL-8. Thus, IFN-λ1 may provide a novel research target for the pathogenesis and therapy of SLE.

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