Platycodin D attenuates diabetic renal ischemia/reperfusion injury by enhancing mitophagy and suppressing MAPK/NF-κB signaling activation

The global incidence of diabetes mellitus (DM) is rapidly rising, and DM worsens renal ischemia/reperfusion (I/R) injury, a major cause of high-mortality acute kidney injury (AKI). Therefore, preventing renal I/R injury in DM is crucial. Platycodin D (PD), a compound from Platycodon grandiflorum roots, is known to activate AMP-activated protein kinase (AMPK). Numerous studies have demonstrated that AMPK activation has protective effects in diabetes mellitus (DM) and ischemia/reperfusion (I/R) injury. However, the impact of PD on renal I/R injury in DM and its underlying mechanisms remain unclear. Our experiments revealed that PD treatment via gavage significantly alleviated kidney tissue damage and cell apoptosis in diabetic renal I/R injury. Additionally, PD reduced reactive oxygen species (ROS) levels, and transmission electron microscopy (TEM) indicated a notable discovery in mitophagosome formation. The expression levels of P-AMPK, light chain 3B (LC3B)-II, PTEN-induced putative protein kinase 1 (PINK1) and Parkin all increased under PD treatment, while sequestosome 1 (P62) level decreased. Importantly, AMPK antagonist Compound C (CC) abolished these effects. Additionally, our transcriptomic profiling revealed that PD treatment significantly suppressed MAPK/NF-κB signaling activation. Through functional rescue experiments, we mechanistically demonstrated that PD-mediated AMPK phosphorylation governs this regulatory axis. AMPK inhibition abolished PD's effects on both MAPK/NF-κB suppression, establishing AMPK activation as the upstream modulator. Overall, PD may reduce renal I/R injury in DM through AMPK/PINK1/Parkin-mediated mitophagy and inhibiting MAPK/NF-κB pathway.