Membranous nephropathy (MN) is one of the leading causes of nephrotic syndrome in adults. However, the current treatment of MN has been a matter of fierce debate for decades, and the needs for more advanced pharmaceuticals are critical for improving the treatment strategies. Sanqi oral solution (SQ), mainly consisting of Radix Astragali and Radix Notoginseng, is a formulated product to treat chronic kidney disease for over 20 years with good efficiency in clinic, while the role of SQ on MN remains unclear. In this study, by establishing an experimental rat model of membranous nephropathy induced by cationic Bovine Serum Albumin (C-BSA), we tried to investigate the effects of SQ. We found that administration of SQ ameliorated MN by reducing proteinuria, elevating serum albumin, and ameliorating pathological renal damages. SQ also significantly reduced the C3 and IgG depositions, and restored podocin and synaptopodin expressions. Furthermore, SQ inhibited the activation of nuclear factor-kappa B (NF-κB) signaling pathway. Our results provide evidence that SQ exerts a novel therapeutic effect on MN via reducing proteinuria, ameliorating renal damage and restoring podocyte injuries, which are associated with the suppression of NFκB.

Idiopathic membranous nephropathy (IMN) is the most common pathological type in adult nephrotic syndrome where podocyte apoptosis was found to mediate the development of proteinuria. Sanqi oral solution (SQ), an effective Chinese herbal preparation clinically used in treatment of IMN for decades, plays an important role in reducing proteinuria, but the underlying mechanisms have not been fully elucidated yet. The current study tested the hypothesis that SQ directly lessens proteinuria in IMN by reducing podocyte apoptosis. To investigate the effects of SQ, we established the experimental passive Heymann nephritis (PHN) rat model induced by anti-Fx1A antiserum in vivo and doxorubicin hydrochloride (ADR)-injured apoptotic podocyte model in vitro. SQ intervention dramatically reduced the level of proteinuria, together with the rat anti-rabbit IgG antibodies, complement C3, and C5b-9 deposition in glomerulus of PHN rats, accompanied by an elevation of serum albumin. Protein expression of synaptopodin, marker of podocyte injury, restored after SQ administration, whereas the electron microscopic analysis indicated that fusion of foot processes, and the pachynsis of glomerular basement membrane was markedly diminished. Further studies showed that SQ treatment could significantly inhibit podocyte apoptosis in PHN rats and ADR-injured podocytes, and protein levels of Cleaved Caspase-3 or the ratio of Bax/Bcl-2 were significantly decreased with SQ treatment in vivo or in vitro. Moreover, we found that the nuclear factor erythroid 2–related factor-2/heme oxygenase 1 (Nrf2/HO-1) pathway mediated the anti-apoptosis effective of SQ in podocyte. Thus, SQ mitigates podocyte apoptosis and proteinuria in PHN rats via the Nrf2/HO-1 pathway.

Membranous nephropathy (MN), the most prevalent form of nephrotic syndrome in non-diabetic adults globally, is currently the second most prevalent and fastest-increasing primary glomerular disease in China. Numerous renal disorders are developed partly due to ferroptosis. However, its relationship to the pathogenesis of MN has rarely been investigated in previous studies; actually, ferroptosis is closely linked to the immune microenvironment and inflammatory response, which might affect the entire process of MN development. In this study, we aimed to identify ferroptosis-related genes that are potentially related to immune cell infiltration, which can further contribute to MN pathogenesis. The microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database. Ferroptosis-related differentially expressed genes (FDEGs) were identified, which were further used for functional enrichment analysis. The common genes identified using the Least Absolute Shrinkage and Selection Operator (LASSO) logistic regression algorithm and the support vector machine recursive feature elimination (SVM-RFE) algorithm were used to identify the characteristic genes related to ferroptosis. The feasibility of the 7 genes as a distinguishing factor was assessed using the receiver operating characteristic (ROC) curve, with the area under the curve (AUC) score serving as the evaluation metric. Gene set enrichment analysis (GSEA) and correlation analysis of these genes were further performed. The correlation between the expression of these genes and immune cell infiltration inferred by single sample gene set enrichment analysis (ssGSEA) algorithm was explored. As a result, 7 genes, including NR1D1, YTHDC2, EGR1, ZFP36, RRM2, RELA and PDK4, which were most relevant to immune cell infiltration, were identified to be potential diagnostic genes in MN patients. Next, the signature genes were validated with other GEO datasets. In the subsequent steps, we conducted quantitative real-time fluorescence PCR (qRT-PCR) analysis and immunohistochemistry (IHC) method on the cationic bovine serum albumin (C-BSA) induced membranous nephropathy (MN) rat model and the passive Heymann nephritis (pHN) rat model to examine characteristic genes. Finally, we analysed the mRNA expression patterns of hub genes in MN patients and normal controls using the Nephroseq V5 online platform. In concise terms, our study successfully identified biomarkers specific to MN patients and delved into the potential interplay between these markers and immune cell infiltration. This knowledge bears significance for the diagnosis and prospective treatment strategies for individuals affected by MN.

Background: Membranous nephropathy (MN) is a chronic glomerular disease that leads to nephrotic syndrome in adults. The aim of this study was to identify novel biomarkers and immune-related mechanisms in the progression of MN through an integrated bioinformatics approach. Methods: The microarray data were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) between MN and normal samples were identified and analyzed by the Gene Ontology analysis, the Kyoto Encyclopedia of Genes and Genomes analysis and the Gene Set Enrichment Analysis (GSEA) enrichment. Hub The hub genes were screened and identified by the weighted gene co-expression network analysis (WGCNA) and the least absolute shrinkage and selection operator (LASSO) algorithm. The receiver operating characteristic (ROC) curves evaluated the diagnostic value of hub genes. The single-sample GSEA analyzed the infiltration degree of several immune cells and their correlation with the hub genes. Results: We identified a total of 574 DEGs. The enrichment analysis showed that metabolic and immune-related functions and pathways were significantly enriched. Four co-expression modules were obtained using WGCNA. The candidate signature genes were intersected with DEGs and then subjected to the LASSO analysis, obtaining a total of 6 hub genes. The ROC curves indicated that the hub genes were associated with a high diagnostic value. The CD4⁺ T cells, CD8⁺ T cells and B cells significantly infiltrated in MN samples and correlated with the hub genes. Conclusions: We identified six hub genes (ZYX, CD151, N4BP2L2-IT2, TAPBP, FRAS1 and SCARNA9) as novel biomarkers for MN, providing potential targets for the diagnosis and treatment.

Membranous nephropathy (MN) is a primary glomerular disease and a major cause of nephrotic syndrome in adults. According to traditional Chinese medicine (TCM) theory, "dampness" is considered a key pathogenic factor. Sanqi Qushi Formula (SQQS), developed by adding dampness-eliminating herbs to Sanqi Oral Liquid, has been shown to improve remission rates in idiopathic MN, although its pharmacological mechanisms are not yet fully clarified. This study investigated whether SQQS attenuates podocyte injury in MN by inhibiting endoplasmic reticulum stress (ERS)-induced ferroptosis. The main components of SQQS were identified and quantified by widely targeted metabolomics. A passive Heymann nephritis (PHN) rat model was established via intravenous injection of anti-Fx1A serum, followed by oral SQQS intervention. Renal function and histopathology were evaluated, and underlying mechanisms were investigated by integrating transcriptomic and proteomic analyses. Structural changes in the endoplasmic reticulum and mitochondria were assessed by transmission electron microscopy. The regulatory effect of SQQS on ERS-induced ferroptosis was further examined using immunohistochemistry, flow cytometry, oxidative stress assays, and related molecular analyses. In vitro, immortalized mouse podocytes MPC-5 were injured with zymosan-activated serum and treated with SQQS-containing serum, the ferroptosis inhibitor Fer-1, the ERS inhibitor 4-PBA, or the ERS activator tunicamycin. The protective effects of SQQS were validated by Western blotting and immunofluorescence. SQQS treatment significantly improved renal function, reduced proteinuria, and alleviated glomerular injury in PHN rats. Histopathological and ultrastructural analyses revealed that SQQS reduced glomerular IgG deposition, basement membrane thickening, fibrosis, and podocyte injury. SQQS dose-dependently restored the expression of key podocyte structural proteins (Nephrin, Synaptopodin, Podocin, α-actinin-4, WT-1) and decreased Desmin levels. Integrated transcriptomic and proteomic analyses identified ERS and ferroptosis as central pathways regulated by SQQS. SQQS suppressed ERS markers (GRP78, p-PERK, p-eIF2α, ATF4, CHOP) and pro-ferroptotic proteins (ACSL4, CHAC1), upregulated antioxidant proteins (GPX4, xCT), reduced iron deposition, and attenuated oxidative stress. In vitro, SQQS-containing serum protected MPC-5 podocytes from ZAS-induced ferroptosis by inhibiting ERS, restoring podocyte marker expression, and enhancing antioxidant defenses. SQQS ameliorates MN by inhibiting the ERS-ferroptosis axis, providing experimental and theoretical support for the application of TCM in the treatment of MN.