MiR-146a relieves kidney injury in mice with systemic lupus erythematosus through regulating NF-κB pathway.

OBJECTIVE: To explore the effect of micro ribonucleic acid (miRNA)-146a on kidney injury in mice with systemic lupus erythematosus (SLE), and to investigate its possible mechanism.

MATERIALS AND METHODS: A total of 45 female MRL/lpr mice were randomly divided into control group, miR-146a mimic group and miR-146a inhibitor group. Urine protein level was measured every 2 weeks. Meanwhile, the levels of serum anti-dsdeoxyribonucleic acid (anti-dsDNA), anti-ssDNA, antinuclear antibody (ANA) and anti-chromatin were measured using enzyme-linked immunosorbent assay (ELISA). At 2 weeks after drug treatment, the effects of miR-146a mimic and inhibitor on kidney tissues of MRL/lpr mice were detected and analyzed by gene chip and gene set enrichment analysis, respectively. The mice were executed at the age of 24 weeks, and the blood samples were collected. Subsequently, the level of blood urea nitrogen (BUN) was measured using the BUN analyzer. After that, kidney tissues were taken, and the effect of drug treatment on the morphology of kidney tissues was detected via hematoxylin-eosin (HE) staining. Moreover, the effects of drug treatment on the mRNA levels of inflammatory factors and the nuclear factor-κB (NF-κB) signaling pathway in kidney tissues were detected via quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting, respectively.

RESULTS: MiR-146a mimic significantly reduced urine protein in a time-dependent manner, which also significantly reduced BUN level at 24 weeks. The results of HE staining showed that both glomerular injury and renal vascular injury in miR-146a mimic group were significantly alleviated. In miR-146a mimic group, serum autoantibodies of anti-dsDNA, anti-ssDNA, anti-chromatin and ANA decreased significantly. However, the survival time of mice was significantly prolonged. High-throughput gene expression chip technique elucidated that in miR-146a mimic group, the expression of positive regulatory gene of NF-κB showed a decreasing trend. However, the expression of negative regulatory gene of NF-κB showed an increasing trend. MiR-146a mimic remarkably down-regulated the expression levels of RELA, IRAK1, interleukin-1B (IL1B) and IL-10 in kidney tissues. Furthermore, the results of Western blotting showed that miR-146a mimic inhibited both the classical and non-classical NF-κB signaling pathways.

CONCLUSIONS: MiR-146a reduces SLE-induced kidney injury in MRL/lpr mice through regulating classical and non-classical NF-κB signaling pathways.