Magnesium Lithospermate B Protects Against Ischemic AKI-to-CKD Progression via Regulating the KLF5/CDK1/Cyclin B1 pathway

Ischemia-reperfusion injury (IRI) is the primary cause of acute kidney injury (AKI), which can result in chronic kidney disease (CKD) with renal fibrosis. Magnesium lithospermate B (Mlb), a bioactive compound produced from Salvia miltiorrhiza Bunge, exerts nephroprotective effects against AKI. However, the significance of Mlb in the evolution of IRI-induced AKI in patients with CKD remains unclear. Notably, the specific mechanisms underlying the putative antifibrotic activities of Mlb during this progression remain to be fully elucidated. This study sought to explore the therapeutic benefits of Mlb in AKI-to-CKD progression and uncover the potential mechanisms, with a special interest in its effects on renal fibrosis and cell cycle regulation. Unilateral ischemia/reperfusion (UIR)-induced mouse AKI-to-CKD progression (in vivo) and HK-2 cells with TGF-β-induced fibrosis model (in vitro) were used in the study. The beneficial effects of Mlb on renal fibrosis and cell cycle-related signaling pathways were investigated using histological analysis, molecular assays, network pharmacology, and RNA sequencing. Mlb treatment significantly reduced renal dysfunction, inflammation, apoptosis, and the G2/M phase cell cycle stalling in mice 14 days post-UIR-induced AKI, subsequently improving renal fibrosis. Mechanistically, Mlb promotes the activity of the CDK1/Cyclin B1 signaling pathway, thereby alleviating the G2/M phase cell cycle stalling. Network pharmacology and RNA sequencing analyses identified the KLF5/CDK1/Cyclin B1 signaling pathway as a potential target of the antifibrotic effects of Mlb, which was further verified in both in vivo and in vitro experiments. The KLF5 inhibitor ML264 attenuated the protective effects of Mlb by reducing CDK1/Cyclin B1 expression and reinstating the G2/M phase cell cycle stalling, highlighting the critical role of this pathway in Mlb-mediated renal protection. Mlb decreases renal fibrosis by inhibiting the G2/M phase cell cycle stalling via the KLF5/CDK1/Cyclin B1 signaling pathway during AKI-to-CKD progression. Our findings offer new insight into the therapeutic potential of Mlb in preventing CKD progression following AKI and identify a previously unrecognized mechanism involving the KLF5/CDK1/Cyclin B1 pathway.