The disruption of the immune tolerance induces autoimmunity such as systemic lupus erythematosus and vasculitis. A chromatin-binding non-histone protein, high mobility group box 1 (HMGB1), is released from the nucleus to the extracellular milieu in particular environments such as autoimmunity, sepsis and hypoxia. Extracellular HMGB1 engages pattern recognition receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation endproducts (RAGE). While the HMGB1-RAGE axis drives inflammation in various diseases, recent studies also focus on the anti-inflammatory effects of HMGB1 and RAGE. This review discusses current perspectives on HMGB1 and RAGE’s roles in controlling inflammation and immune tolerance. We also suggest how RAGE heterodimers responding microenvironments functions in immune responses.

Systemic lupus erythematosus (SLE) damages multiple organs by producing various autoantibodies. In this study, we report that decreased microRNA (miR)-200a-3p causes IL-2 hypoproduction through zinc finger E-box binding homeobox (ZEB)1 and C-terminal binding protein 2 (CtBP2) in a lupus-prone mouse. First, we performed RNA sequencing to identify candidate microRNAs and mRNAs involved in the pathogenesis of SLE. We found that miR-200a-3p was significantly downregulated, whereas its putative targets, ZEB2 and CtBP2, were upregulated in CD4⁺ T cells from MRL/lpr-Tnfrsf6^lpr mice compared with C57BL/6J mice. ZEB1 and ZEB2 comprise the ZEB family and suppress various genes, including IL-2 by recruiting CtBP2. IL-2 plays a critical role in immune tolerance, and insufficient IL-2 production upon stimulation has been recognized in SLE pathogenesis. Therefore, we hypothesized that decreased miR-200a-3p causes IL-2 deficit through the ZEB1–CtBP2 and/or ZEB2–CtBP2 complex in SLE CD4⁺ T cells. Overexpression of miR-200a-3p induced IL-2 production by downregulating ZEB1, ZEB2, and CtBP2 in EL4 cell lines. We further revealed that miR-200a-3p promotes IL-2 expression by reducing the binding of suppressive ZEB1–CtBP2 and ZEB2–CtBP2 complexes on negative regulatory element A in the IL-2 promoter in EL4 cells. Interestingly, the ZEB1–CtBP2 complex on negative regulatory element A was significantly upregulated after PMA/ionomycin stimulation in lupus CD4⁺ T cells. Our studies have revealed a new epigenetic pathway in the control of IL-2 production in SLE whereby low levels of miR-200a-3p accumulate the binding of the ZEB1–CtBP2 complex to the IL-2 promoter and suppress IL-2 production.

Objectives: To determine prognostic factors of methotrexate-associated lymphoproliferative disorder (MTX-LPD) and evaluate the efficacy and safety of biological therapy in rheumatoid arthritis (RA) complicated with MTX-LPD. Methods: Thirty RA patients who developed MTX-LPD were investigated in this study. We compared the clinical and laboratory parameters of patients who achieved regression of LPD by MTX withdrawal with those who required chemotherapy and evaluated the clinical course of RA after LPD development. Results: Twenty-three patients (76.7%) achieved regression of LPD by MTX withdrawal. Chemotherapy-free patients had a tendency of shorter RA duration (13.1 vs. 22.0 years, p = 0.108) and higher doses of MTX at LPD diagnosis (8.0 vs. 5.3 mg/w, p = 0.067) than patients who required chemotherapy. A significantly higher positive rate of peripheral blood Epstein–Barr virus (EBV)-DNA was observed in the chemotherapy-free group (9/9 vs. 0/3, p = 0.0002). Of 15 patients that received biological agents after LPD development, 14 patients (93.3%) demonstrated an improved disease activity of RA and persistent remission of LPD, whereas only one patient experienced relapse of LPD during tocilizumab therapy. Conclusions: Peripheral blood EBV-DNA positivity is a potential prognostic marker of better outcome in MTX-LPD. Biological agents could be an option for the treatment of RA patients with MTX-LPD.