MiR-146b-5p/ERBB4 Axis Drives LPS-induced Acute Kidney Injury by Modulating NF-κB/p65.

We aimed to explore the role of miR-146b-5p in lipopolysaccharide (LPS)-induced acute kidney injury. C57BL/6N mice were intraperitoneally injected with LPS to establish an acute kidney injury model, and the effects of miR-146b-5p inhibition on AKI progression in vivo were explored. The renal function of mice was evaluated by determining serum creatinine and blood urea nitrogen levels. Kidney histopathology was examined using H&E and PAS staining. Cell apoptosis in vivo was analyzed via TUNEL staining, and the TUNEL-positive cells per field were quantified. HK-2 cells were stimulated with LPS (1 µg/mL) to replicate an inflammatory AKI environment in vitro. To investigate function and molecular mechanisms of miR-146b-5p, HK-2 cells were transfected with mimics and inhibitor of miR-146b-5p. Apoptosis in HK-2 cells was assessed via flow cytometry using Annexin-V/FITC and propidium iodide (PI) staining, while levels of inflammatory cytokine (IL-1β, IL-6, TNF-α) were measured using ELISA. RNA pull-down and luciferase assays were used to explore interaction between miR-146b-5p and ERBB4 and activation of the downstream NF-κB/p65 signaling was investigated via western blot. The results showed that miR-146b-5p expression was upregulated by ~ 133% in the LPS-induced AKI mouse model (p < 0.01) and increased up to ~ 137% in LPS-treated HK-2 cells (p < 0.001) compared to control. Inhibition of miR-146b-5p improved renal function, and BUN levels were reduced by ~ 48% (p < 0.01) and creatinine levels were decreased by ~ 40% compared to LPS + NC antagomir group (p < 0.01). Inhibition of miR-146b-5p also attenuated tissue injury, suppressed cell apoptosis, with the TUNEL-positive cells reduced by 46% compared to LPS + NC antagomir group (p < 0.01), and lowered inflammatory cytokine levels, with IL-1β reduced by ~ 54% (p < 0.01), IL-6 reduced by ~ 55% (p < 0.01), and TNF-α reduced by 51% (p < 0.01) compared to LPS + NC antagomir group. Mechanistically, miR-146b-5p directly targeted ERBB4, whose suppression reversed the protective effects of miR-146b-5p inhibition. Importantly, we found that the miR-146b-5p/ERBB4 axis regulates the NF-κB/p65 signaling pathway, providing a potential mechanistic link between miRNA activity and inflammation in AKI. In conclusion, this study reveals that the miR-146b-5p/ERBB4 axis promotes the activation of the NF-κB pathway and drives apoptosis and inflammation in LPS-induced AKI, suggesting miR-146b-5p as a novel therapeutic target for AKI.