Mitochondrial DNA Release Activates cGAS-STING Signaling in Membranous Nephropathy: Therapeutic Attenuation by Pathway Inhibition

Background Membranous nephropathy (MN) is a chronic kidney disease mediated by autoimmunity, but its molecular mechanisms remain incompletely understood. Studies have suggested that mitochondrial damage leading to mitochondrial DNA (mtDNA) leakage may contribute to the development of autoimmune diseases by activating the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, but this mechanism has not yet been explored in MN. Methods In this study, an MN animal model was established in Balb/c mice using cationic bovine serum albumin (cBSA) induction. Concurrently, an in vitro podocyte injury model was generated by stimulating cultured podocytes with Zymosan. Mitochondrial damage was assessed by quantifying the relative abundance of mtDNA in total cellular and cytosolic fractions via quantitative PCR (qPCR). Interventions were performed using the cGAS inhibitor RU.521 and STING inhibitor C-176. The therapeutic effects of inhibiting the cGAS-STING pathway were systematically evaluated through in vivo and in vitro assessments of urinary protein levels, glomerular immune complex deposition, podocyte injury markers, and mitochondrial functional parameters. Results Integrated in vivo and in vitro experimental results confirm that MN induces mitochondrial dysfunction and triggers mtDNA leakage into the cytosol, thereby activating the cGAS-STING signaling pathway. Intervention with the cGAS-specific inhibitor RU.521 or the STING inhibitor C-176 demonstrated significant renoprotective effects in both animal and cellular models. In the cBSA-induced MN mouse model, the treatment groups exhibited significantly reduced urinary protein levels, decreased glomerular IgG and C3 deposition, and significant downregulation of inflammatory cytokines (IL-1β, IL-6, TNF-α). Similarly, in vitro podocyte experiments showed that inhibitor treatment reversed the Zymosan-induced reduction in mitochondrial membrane potential and decreased mitochondrial superoxide levels. These findings collectively demonstrate the therapeutic potential of targeting the cGAS-STING pathway in MN. Conclusion Our study unveils a critical role for the cGAS-STING signaling pathway in the development and progression of MN. Targeted inhibition of this pathway confers remarkable renal protection, highlighting its potential as a novel therapeutic strategy for managing MN.