Downregulation of miR-34a ameliorates inflammatory response and apoptosis induced by renal ischemia-reperfusion by promoting Kruppel-like factor 4 expression

Y.-Y. Shi, Y.-H. Ma, R. Zhang, R.-S. Li

Department of Nephrology Division, Second Hospital of Shanxi Medical University, Taiyuan, China. rongshanli13@163.com

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• Nephrology

OBJECTIVE: To explore the influence of micro ribonucleic acid (miR)-34a on renal ischemia-reperfusion by regulating Kruppel-like factor 4 (KLF4).

MATERIALS AND METHODS: A total of 36 Sprague-Dawley (SD) rats weighing 180-200 g were randomly divided into sham operation group (n=12), model group (n=12), and miR-34a inhibitor group (n=12). Renal ischemia-reperfusion modeling was performed in rats of model group and miR-34a inhibitor group. Those in the sham operation group received the same procedures without ligation. 200 μL of miR-34a inhibitor was pre-injected before modeling in rats of miR-34a inhibitor group. An automatic biochemical analyzer was used to detect serum creatinine and urea nitrogen levels in each group of rats, thus reflecting renal functions. The expressions of B-cell lymphoma 2 (Bcl-2), an apoptotic protein, and KLF4, a transcription factor, were detected via Western blotting. Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assay was conducted to measure the expression levels of miR-34a and KLF4 in rat renal tissues in each group. Immunohistochemistry was employed to determine the expressions of inflammatory factors tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10). Additionally, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining was utilized to determine the apoptotic rate in rat kidney tissues in each group.

RESULTS: Compared with those in the sham operation group, serum creatinine level, urea nitrogen level, expressions of miR-34a, TNF-α and Bcl-2 (p<0.05) increased, while the levels of KLF4 and IL-10 (p<0.05) decreased in the model group. Apoptosis rate was also higher in the model group than the controls. In comparison with the model group, miR-34a inhibitor group had lowered serum creatinine level, urea nitrogen level, expressions of miR-34a, TNF-α and Bcl-2, and apoptotic rate (p<0.05), but raised levels of KLF4 and IL-10 (p<0.05), showing statistically significant differences.

CONCLUSIONS: Downregulation of miR-34a ameliorates inflammatory response and apoptosis induced by renal ischemia-reperfusion by promoting KLF4 level, thus improving renal functions in rats.

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