Melatonin Alleviates Acute Kidney Injury by Inhibiting NRF2/Slc7a11 Axis-Mediated Ferroptosis.

Acute kidney injury (AKI) is still a puzzling clinical problem; its pathophysiology is not completely understood. Up to now, an effective treatment for AKI is lacking. Ferroptosis is a novel form of regulated cell death characterized by the lethal accumulation of lipid hydroperoxides that are dependent on iron and reactive oxygen species and mitochondrial dysfunction. Recently, ferroptosis was shown to play a vital role in AKI such as ischemia-reperfusion kidney injury and folic acid-induced AKI. Melatonin (MT) is an antioxidant that regulates the sleep-wake cycle. While the therapeutic effect of melatonin on AKI has been reported, its mechanism for the treatment of renal ferroptosis remains unclear. We found that melatonin treatment significantly alleviated the serum biochemistry index and histopathological alterations in vivo AKI models induced by bilateral renal artery ischemia reperfusion and folic acid in mice. Ferroptosis induced by hypoxia and reoxygenation or erastin (Era) in mouse tubular epithelial cells (MTEC) was also rescued by melatonin treatment. RNA sequence analysis of ferroptosis-related genes showed that melatonin affects oxidative stress responses by inhibiting hypoxia and reoxygenation- (HR-) mediated downregulation of NRF2 and upregulation of Slc7a11 in MTEC. Specific knockdown of NRF2 increased the sensitivity of cells to ferroptosis, and melatonin failed to protect against ferroptosis in the HR condition. Together, our data indicate that melatonin prevents ferroptosis in AKI by acting on the NRF2/Slc7a11 axis.

Wogonin protects glomerular podocytes by targeting Bcl-2-mediated autophagy and apoptosis in diabetic kidney disease.

Diabetic kidney disease (DKD) is one of the microvascular complications of diabetes mellitus and a major cause of end-stage renal disease with limited treatment options. Wogonin is a flavonoid derived from the root of Scutellaria baicalensis Georgi, which has shown a potent renoprotective effect. But the mechanisms of action in DKD are not fully elucidated. In this study, we investigated the effects of wogonin on glomerular podocytes in DKD using mouse podocyte clone 5 (MPC5) cells and diabetic mice model. MPC5 cells were treated with high glucose (30 mM). We showed that wogonin (4, 8, 16 µM) dose-dependently alleviated high glucose (HG)-induced MPC5 cell damage, accompanied by increased expression of WT-1, nephrin, and podocin proteins, and decreased expression of TNF-α, MCP-1, IL-1ß as well as phosphorylated p65. Furthermore, wogonin treatment significantly inhibited HG-induced apoptosis in MPC5 cells. Wogonin reversed HG-suppressed autophagy in MPC5 cells, evidenced by increased ATG7, LC3-II, and Beclin-1 protein, and decreased p62 protein. We demonstrated that wogonin directly bound to Bcl-2 in MPC5 cells. In HG-treated MPC5 cells, knockdown of Bcl-2 abolished the beneficial effects of wogonin, whereas overexpression of Bcl-2 mimicked the protective effects of wogonin. Interestingly, we found that the expression of Bcl-2 was significantly decreased in biopsy renal tissue of diabetic nephropathy patients. In vivo experiments were conducted in STZ-induced diabetic mice, which were administered wogonin (10, 20, 40 mg · kg-1 · d-1, i.g.) every other day for 12 weeks. We showed that wogonin administration significantly alleviated albuminuria, histopathological lesions, and p65 NF-κB-mediated renal inflammatory response. Wogonin administration dose-dependently inhibited podocyte apoptosis and promoted podocyte autophagy in STZ-induced diabetic mice. This study for the first time demonstrates a novel action of wogonin in mitigating glomerulopathy and podocytes injury by regulating Bcl-2-mediated crosstalk between autophagy and apoptosis. Wogonin may be a potential therapeutic drug against DKD.