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Mesenchymal stem cells (MSCs) are critical for immune regulation. Although several microRNAs (miRNAs) have been shown to participate in autoimmune pathogenesis by affecting lymphocyte development and function, the roles of miRNAs in MSC dysfunction in autoimmune diseases remain unclear. Here, we show that patients with systemic lupus erythematosus (SLE) display a unique miRNA signature in bone marrow-derived MSCs (BMSCs) compared with normal controls, among which miR-663 is closely associated with SLE disease activity. MiR-663 inhibits the proliferation and migration of BMSCs and impairs BMSC-mediated downregulation of follicular T helper (T) cells and upregulation of regulatory T (T) cells by targeting transforming growth factor β1 (TGF-β1). MiR-663 overexpression weakens the therapeutic effect of BMSCs, while miR-663 inhibition improves the remission of lupus disease in MRL/lpr mice. Thus, miR-663 is a key mediator of SLE BMSC regulation and may serve as a new therapeutic target for the treatment of lupus.Cellular and Molecular Immunology advance online publication, 26 March 2018; doi:10.1038/cmi.2018.1.

Recent evidence indicates that artesunate has immunomodulatory properties that might be useful for treating autoimmune disease. In this study, we conducted a pilot study and explored the effect and mechanism of artesunate on the treatment of systemic lupus erythematosus using an MRL/lpr murine model. MRL/lpr mice were divided into control, cyclophosphamide (CTX) and artesunate treatment groups. Blood was collected to measure serum levels of creatinine, antinuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibody. Twenty-four-hour urine was collected to measure levels of proteinuria. The concentration of monocyte chemotactic protein-1 (MCP-1) in serum and urine was measured. The expression of MCP-1 in kidney was detected by Western blot and immunohistochemistry assay, respectively. The expression of B cell activating factor (BAFF) in spleen was determined by real time-PCR and immunoblotting. We found that artesunate significantly increased the survival rate, body weight and blood leukocyte counts, and reduced the serum levels of ANA and anti-dsDNA antibody titer, 24 h urinary protein, and serum creatinine. Our results indicated that artesunate could decrease MCP-1, major pro-inflammation cytokine, in serum, urine and kidney. We also found that the level of BAFF, the major B cell activation factor, was decreased in artesunate treated MRL/lpr mice. Its efficacy was comparable with that of CTX in this study. Taken

Th17 cells contribute to the development of autoimmune diseases by secreting interleukin-17 (IL-17), which activates its receptor (IL-17R) that is expressed on epithelial cells, macrophages, microglia, and resident neuroectodermal cells. However, the mechanisms through which IL-17R-mediated signaling contributes to the development of autoimmune disease have not been completely elucidated. Here, we demonstrate that Raf-1 kinase inhibitor protein (RKIP) deficiency in mice ameliorates the symptoms of experimental autoimmune encephalomyelitis (EAE). Adoptive T-cell-transfer experiments demonstrate that RKIP plays a predominant role in Th17-mediated, but not in Th1-mediated immune responses. RKIP deficiency has no effect on Th17-cell differentiation , nor does it affect Th17-cell differentiation in EAE mice. However, RKIP significantly promotes IL-17R-induced proinflammatory cytokine and chemokine production. Mechanistically, RKIP directly interacts with IL-17RA and Act1 to promote the formation of an IL-17R-Act1 complex, resulting in enhanced MAPK- and P65-mediated NF-κB activation and downstream cytokine production. Together, these findings indicate that RKIP functions as an essential modulator of the IL-17R-Act1 axis in IL-17R signaling, which promotes IL-17-induced inflammation and autoimmune neuroinflammation.

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