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

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. This study investigated the mechanisms of SSR's renoprotective actions under chronic hypoxia condition of CKD. 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. 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. SSR inhibits hypoxia-induced oxidative stress and ferroptosis to ameliorate renal fibrosis in CKD via Nrf2 activation.