Baicalein ameliorates polymyxin B-induced acute renal injury by inhibiting ferroptosis via regulation of SIRT1/p53 acetylation

The polypeptide antibiotic Polymyxin B (PMB) can cause acute kidney injury (AKI), we found that ferroptosis is one of the main mechanisms of renal injury caused by PMB. It was reported that baicalein can inhibit ferroptosis. Therefore, in this study we examined whether baicalein could attenuate PMB-induced renal injury by inhibiting ferroptosis. We confirmed that baicalein could reduce PMB-induced renal injury in vivo and in vitro studies. In the in vitro study, baicalein significantly increased the survival rate of human HK2 tubular epithelial cells. The results of HE staining and electron microscopy in mice also showed that baicalein reduced PMB-induced renal injury, and significantly decreased the levels of BUN and Scr. By detecting ferroptosis-related indicators, we found that pre-incubation of baicalein in HK2 cells down-regulated Fe2+ level, lipid peroxidation, MDA and HO-1 which had been increased by PMB. Furthermore, baicalein up-regulated the levels of SCL7A11, GPX4 and GSH that were decreased by PMB. Moreover, intraperitoneal injection of baicalein in the animal model down-regulated kidney iron level, PTGS2 and 4HNE, and increased the GSH level, which suggested that baicalein could inhibit PMB-induced ferroptosis. Finally, by detecting changes in levels of p53 and p53 K382 acetylation, baicalein was observed to decrease elevated p53 K382 acetylation after PMB treatment, further confirming that baicalein inhibits ferroptosis by reducing p53 K382 acetylation via upregulation of SIRT1 expression. In conclusion, these results suggest that baicalein decreases p53 acetylation level by elevating SIRT1, which can then inhibit PMB-induced ferroptosis and ultimately attenuates AKI.