Shen-Shuai-II-Recipe suppresses hypoxia-induced oxidative stress and ferroptosis via Nrf2 activation to ameliorate renal fibrosis in chronic kidney disease.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE: Shen-Shuai-II-Recipe (SSR), a clinically effective Chinese herbal formula for chronic kidney disease (CKD) management, has shown potential anti-hypoxia and anti-fibrosis properties in rat models of CKD. However, the underlying molecular mechanisms of its renoprotection warrant further elucidation. AIM OF THE STUDY: This study investigated the mechanisms of SSR's renoprotective actions under chronic hypoxia condition of CKD. MATERIALS AND METHODS: In vivo, 5/6 renal ablation/infarction (A/I) rat models of CKD were established and administered with SSR or losartan for eight weeks. In vitro, NRK-52E cells underwent chronic hypoxia induction and were treated with SSR-medicated serum and (or) Nrf2 inhibitor (ML385). Renal hypoxia, oxidative stress, ferroptosis, and fibrosis were assessed via blood oxygenation level-dependent MRI, histopathology, colorimetry, immunoblotting, and fluorometry. RESULTS: SSR significantly suppressed oxidative stress and ferroptosis in 5/6 (A/I) kidneys, concomitant with alleviated hypoxia and fibrosis, which was associated with the up-regulated expression of Nrf2 protein. Hypoxic NRK-52E cells exhibited time-dependent increases in fibrosis and hypoxia-related proteins and suppression of the Nrf2 pathway. Furthermore, SSR significantly improved antioxidant capacity, attenuated lipid peroxidation and fibrosis in chronic hypoxia induced NRK-52E cells by activating the Keap1-Nrf2/xCT/GPX4 axis, while the effect was diminished by Nrf2 inhibition. CONCLUSIONS: SSR inhibits hypoxia-induced oxidative stress and ferroptosis to ameliorate renal fibrosis in CKD via Nrf2 activation.