INHBA knockdown inhibits renal fibrosis in mice following ischemia-reperfusion injury by suppressing activation of the TGF-β/Smad signaling pathway.

BACKGROUND: Acute kidney injury (AKI) and renal fibrosis are clinical conditions associated with high morbidity and mortality. Renal ischemia-reperfusion (I/R) injury is a major cause of AKI. OBJECTIVE: This study aimed to investigate the role of inhibin subunit beta A (INHBA) in the pathogenesis of renal fibrosis and the underlying mechanisms during I/R-induced kidney injury using an in vivo model. METHODS: A mouse model of renal I/R injury was established. INHBA function was evaluated by intrarenal injection of INHBA-short hairpin RNA (INHBA-shRNA) on day 7 after I/R. Renal function, tubular damage, and interstitial fibrosis were assessed using detection kits, hematoxylin-eosin staining, and Masson's trichrome staining. reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analyses were performed to examine the expression of fibrosis-related genes, including fibronectin (FN), collagen I (Col-I), and alpha-smooth muscle actin (α-SMA). Additionally, RT-qPCR, Western blot, and immunohistochemistry were used to determine INHBA expression in different groups. Transforming growth factor beta 1 (TGF-β1) levels in kidney tissue were measured by enzyme-linked immunosorbent assay. The effect of INHBA-shRNA on the TGF-β/Smad signaling pathway was analyzed by Western blot. RESULTS: INHBA-shRNA significantly reduced INHBA expression, serum creatinine levels, 24-hour urinary albumin, and urinary albumin-to-creatinine ratio in I/R-injured mice. It also alleviated renal tubular damage and interstitial fibrosis. Furthermore, INHBA knockdown downregulated the expression of fibrosis markers, inhibited TGF-β1 secretion, and suppressed activation of the TGF-β/Smad signaling pathway, as evidenced by reduced expression of FN, Col-I, α-SMA, phosphorylated Smad2, and phosphorylated Smad3. CONCLUSION: Knockdown of INHBA attenuates renal fibrosis after I/R injury in mice by suppressing activation of the TGF-β/Smad signaling pathway. This pathway may represent a potential therapeutic target for renal I/R injury.