Sanqi Qushi formula ameliorates renal injury in experimental membranous nephropathy rats by inhibiting the MEK/ERK signaling pathway

Ethnopharmacological relevance Sanqi Qushi Formula (SQQS), a clinically validated derivative of the Sanqi oral solution, integrates principles of traditional Chinese medicine (TCM) to treat membranous nephropathy (MN). Its efficacy in reducing proteinuria and preserving renal function has been observed in clinical practice. Aim of the study This study aims to elucidate the therapeutic mechanisms, active components, and pathway-specific effects of SQQS in MN, providing a scientific foundation for its clinical use. Materials and methods The components of SQQS were analyzed using UHPLC-MS/MS. A passive Heymann nephritis (PHN) rat model was induced by intravenous injection of anti-Fx1A serum. Rats received oral SQQS for 3 weeks, and urine/serum samples were collected to evaluate renal function and chemokine levels. Renal histopathology was assessed via immunofluorescence, PASM staining, and CD68 immunostaining. Network pharmacology integrated target prediction for SQQS compounds and differentially expressed genes from the Gene Expression Omnibus (GEO) database (MN patient glomeruli). Mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway proteins and epithelial-mesenchymal transition (EMT) markers were analyzed by western blotting (WB). Molecular docking and molecular dynamics simulations evaluated compound-MEK interactions. Human glomerular podocytes were treated with SQQS-derived compounds; viability and migration were assessed using cell counting kit-8 assay and scratch assays. Results UHPLC-MS/MS identified 129 compounds in SQQS. SQQS treatment significantly reduced renal injury markers, glomerular IgG deposition, and basement membrane thickening in PHN rats. GEO database analysis revealed 839 upregulated and 166 downregulated genes in MN glomeruli. Network pharmacology implicated the tumor necrosis factor (TNF) pathway, with 10 upregulated targets (e.g., MAP2K1, MMP3 , CXCL10). WB confirmed SQQS suppressed MEK/ERK phosphorylation and decreased MMP3 and α-SMA levels. Renal CD68 + macrophages and associated chemokines (CXCL10, CCL20) were reduced by SQQS. Methylnissolin-3-O-glucoside, a flavonoid from Astragalus mongholicus Bunge, dose-dependently inhibited TNF-α-induced MEK/ERK activation and migration. MEK agonists reversed methylnissolin-3-O-glucoside-mediated MEK/ERK suppression. Conclusion SQQS ameliorates MN progression by inhibiting the MEK/ERK pathway, suppressing EMT, and reducing macrophage recruitment, with methylnissolin-3-O-glucoside as a key bioactive component.