The anti-inflammatory effects of Hedyotis diffusa Willd on SLE with STAT3 as a key target

Hedyotis diffusa Willd, also named Scleromitrion diffusum (Willd.) R.J. Wang, is one medical herb, which has been traditionally used by the She nationality in China. And H. diffusa represents a beneficial effect on Systemic lupus erythematosus (SLE) treatment in clinic.The underlying mechanisms of the protective effects of H. diffusa on SLE remain unclear. In this study, we treated MRL/lpr mice with H. diffusa water extract (HDW) to assess its therapeutic effects and verified its regulating signalling pathway through cytological experiments.In the present study, the constituents of HDW were analysed through ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and SCIEX OS software. The protective activity and underlying mechanisms were studied in a MRL/lpr lupus mouse model. The blood cells, autoantibodies, metabolites and the cytokines in serum were identified with a hematology analyzer, specific ELISA kit, GC/MS system and cytometric assays. The histological and immunohistochemical analysis were engaged in the morphologic, and the expression and translocation of the crucial protein observation. The dual luciferase reporter assay was applied to identifying the regulative activity of HDW. The transcription and translation expression of the protein was studied by real-time PCR and Western blot assays. The network pharmacology analysis was employed to predict the IL-6/STAT3 pathway regulators and the screen the STAT3 inhibitors in HDW.The results revealed the capability of HDW to attenuate the production of autoantibodies, secretion of inflammatory cytokines (IL-6 and IFN-γ), and suppressed the IgG and C3 deposition, the development of glomerular lesions in MRL/lpr mice. Serum metabolomics study showed the improvement in serum metabolites, especially aminoacyl-tRNA biosynthesis, by HDW. IL-6 was clarified to be highly associated with the significantly changed metabolites in network analysis. We further demonstrated the effects of HDW on the IL-6/STAT3 pathway in vivo and in vitro.This study suggested that HDW exerts a therapeutic effect in SLE model mice by suppressing the IL-6/STAT3 pathway.