Qing-Re-Xiao-Zheng-(Yi-Qi) formula attenuates the renal podocyte ferroptosis in diabetic kidney disease through AMPK pathway

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetic kidney disease (DKD), a prevalent microvascular complication of diabetes, is a leading cause of end-stage renal disease (ESRD). Emerging evidence implicates ferroptosis in DKD pathogenesis. Qing-Re-Xiao-Zheng-(Yi-Qi) Formula (QRXZYQF), a traditional Chinese medicine with a 30-year clinical application history, exhibits multifaceted pharmacological benefits. But its potential role in DKD has yet to be fully investigated. AIM OF THE STUDY: This study investigates whether QRXZYQF alleviates podocyte injury and mitigates DKD progression by modulating ferroptosis through AMP-activated protein kinase (AMPK) pathway activation. MATERIALS AND METHODS: We induced DKD in male sprague dawley (SD) rats by performing left unilateral nephrectomy followed by a single intraperitoneal injection of streptozotocin (STZ, 50 mg/kg). Rats received QRXZYQF (12/24 g/kg), metformin (100 mg/kg), and valsartan (8 mg/kg) for 16 weeks. Renal function, blood glucose, lipid profiles, 24-h urinary protein (24 h-UTP), oxidative stress markers glutathione (GSH) and malondialdehyde (MDA), and histopathology were assessed. In vitro, high-glucose-cultured conditionally immortalized mouse podocytes (MPC-5) cells were analyzed for cell viability assays, ferroptosis markers, mitochondrial integrity, and AMPK signaling. Additionally, we used short hairpin RNA (shRNA) to suppress AMPK expression to confirm whether QRXZYQF exerts protective effects on DKD via AMPK-mediated ferroptosis signaling. RESULTS: QRXZYQF improved body weight, glucose-lipid metabolism, and renal function in DKD rats, and alleviated kidney tissue pathology, renal fibrosis and mitochondrial damage. Furthermore, QRXZYQF upregulated the expression of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) while downregulating acyl CoA synthase long-chain family member 4 (ACSL4) expression, and attenuated oxidative stress. Moreover, AMPK silencing partially reversed QRXZYQF's protective effects, confirming AMPK-dependent ferroptosis inhibition. CONCLUSIONS: QRXZYQF attenuates DKD progression by activating AMPK signaling, thereby suppressing podocyte ferroptosis. These findings underscore its potential as a therapeutic agent for DKD.