Effects of inflammation on hypoxic renal tubular epithelial cell injury under high-glucose conditions and the regulatory role of miR-125b.

This study examined the impact of inflammation on hypoxic renal tubular epithelial cell (RTEC) injury in a hyperglycemic environment, emphasizing the regulatory role of miR-125b and the mechanisms by which diabetes influences acute kidney injury. A hypoxia/reoxygenation (H/R) model was established in mouse RTECs. Mouse RAW264.7 macrophages were pre-treated under seven conditions: high glucose (HG), normal glucose (NG), HG + miR-125b inhibition (HG + miR-125b inhibitor), HG control (HG + vector), mannitol control (NG + mannitol), and M1/M2 macrophage positive controls. Each group was co-cultured with hypoxic/reoxygenated RTECs for 24 h. The optimal H/R model was achieved with 4 h of hypoxia followed by 24 h of reoxygenation. Macrophages pre-treated with HG and co-cultured with H/R RTECs showed significantly increased apoptosis, reactive oxygen species (ROS) fluorescence intensity, and epithelial injury/oxidative stress markers (lactate dehydrogenase [LDH] and malondialdehyde [MDA]), along with decreased antioxidant superoxide dismutase (SOD) levels. IL-1β levels significantly increased, while IL-10 levels decreased. All renal tubular injury markers increased significantly (P < 0.01 or P < 0.05). However, miR-125b inhibition reduced apoptosis, ROS, LDH, MDA, and renal injury marker levels while increasing SOD and IL-10 levels (P < 0.01 or P < 0.05). Thus, hyperglycemia-induced macrophage polarization toward the M1 phenotype exacerbates hypoxic RTEC damage, which can be partially mitigated by miR-125b inhibition.