Zhen-Wu-Tang decoction ameliorates lupus nephritis by diminishing renal tissue-resident memory CD8+ T cells via suppressing IL15/STAT3 pathway

Background Zhen-Wu-Tang (ZWT), a traditional herbal formula, has been recommended for treating lupus nephritis (LN) in clinic, but the mechanisms underlying its effects remain unclear. Here we aimed to define the immunological mechanisms underlying its effects on LN. Methods In this study, murine LN was induced by a single injection of pristane, while in vitro T RM cells differentiated in the presence of IL-15/TGF-β. The 24h-urine protein, serum creatinine (Scr), serum anti-dsDNA Ab, H&E stain and renal depositions of IgG/complement 3 (C3) were measured to evaluate renal injury and function. Immunoassays, including immunohistochemistry, immunofluorescence, flow cytometry and ELISA, were performed to quantify T RM cells, macrophages polarization and STAT activation both in vivo and in vitro. Results We found that ZWT or mycophenolate mofetil treatment significantly ameliorated kidney injury in LN mice by decreasing 24-h urine protein, Scr and anti-dsDNA Ab. ZWT also improved renal histology and reduced the deposition of IgG and C3. In addition, ZWT downregulated renal desmin expression. Moreover, it significantly reduced the number of renal CD8 + T RM in LN mice while decreasing expression of TNF-α and IFN-γ, but not ki67, in renal CD8 + T RM cells. Consistent with in vivo results, ZWT-containing serum inhibited T RM cell differentiation induced by IL-15/TGF-β ex vivo, but it had no effect on ki67 expression. Importantly, ZWT reduced the number of total F4/80 + CD11b + and CD86 + , but not CD206 + , macrophages in the kidney of LN mice. Interestingly, ZWT decreased IL-15 protein expression in the kidney tissue of LN mice. Further, it mainly suppressed phosphorylation of STAT3 in CD8 + T RM cells in vitro . Conclusions We have provided the first evidence that ZWT decoction can be used to improve LN outcome by reducing CD8 + T RM cells via inhibition of IL-15/STAT3 signaling.