Protective effect of miR-146 against kidney injury in diabetic nephropathy rats through mediating the NF-κB signaling pathway.

OBJECTIVE: To study the protective effect of micro ribonucleic acid (miR)-146 against kidney injury in diabetic nephropathy (DN) rats through the nuclear factor-kappa B (NF-kappa B) signaling pathway. MATERIALS AND METHODS: In this experiment, 30 adult Sprague-Dawley rats with 5-6 weeks old and weighing 20-30 g were selected and randomly divided into control group (n=10), model group (n=10), and miR-146 Mimic group (n=10, DN rat model + miR-146 Mimic). The serum levels of creatinine (Cr) and blood urea nitrogen (BUN) in the three groups were detected using the full-automatic biochemical analyzer. The protein expression levels of phosphorylated-inhibitor of NF-kappa B (p-I kappa B), p-P65, P65, and Tubulin were detected via Western blotting. The messenger RNA (mRNA) of P65 was determined using quantitative Polymerase Chain Reaction (qPCR). Positive expression of p-I kappa B in tissues was determined using immunohistochemistry. Moreover, the contents of inflammatory factors tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 were detected using the enzyme-linked immunosorbent assay (ELISA) kits. Finally, the apoptosis was detected through Annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) dual-fluorescence labeling. RESULTS: The serum levels of Cr and BUN were significantly higher in the model group than those in the control group (p<0.01). while they were significantly lower in miR-146 Mimic group than those in the model group (p<0.05). The levels of p-I kappa B and p-P65/P65 significantly increased in the model group compared with those in the control group (p<0.01). while they remarkably declined in the miR-146 Mimic group compared with those in the model group (p<0.05). The results of qPCR showed that the mRNA level of P65 had no significant difference among the three groups (p>0.05). The immunohistochemical assay showed that the positive expression of p-I kappa B in tissues was consistent with those of the protein level as Western blotting revealed. The rats in the model group had evidently increased levels of TNF-alpha, IL-1 beta, and IL-6 compared with the control group (p<0.01), while miR-146 Mimic group had evidently decreased levels of them compared with the model group (p<0.01). Finally, apoptosis was enhanced in the model group compared with that in the control group, while it was remarkably inhibited in the miR-146 Mimic group. CONCLUSIONS: MiR-146 can inhibit the NF-kappa B signaling pathway, lower the levels of TNF-alpha. IL-1 beta, and IL-6, and reduce the apoptosis, thereby exerting a protective effect against kidney injury in DN.