Hyperglycemia- Induced NF-κB Activation Increases microRNA-146a Expression in Human Umbilical Vein Endothelial Cells

Background & objectives: Nuclear Factor kappa B (NF-κB), a master switch transcription factor, plays a critical role in the progression and development of hyperglycemia-induced microangiopathy. Hyperglycemia activates NF-κB, and subsequently increases pro-inflammatory cytokines such as TNF-α, IL-6 and IL-1β leading to development of inflammation. Some new studies have revealed the involvement of microRNA-146a (miR-146a) in the pathogenesis of diabetic complications through an NF-κB-dependent negative feedback loop manner. Despite numerous reports indicating changes of plasma miR-146a during hyperglycemia, the origin of this change remains unclear. This study was designed to evaluate the role of NF-κB on the miR-146a gene expression level in human umbilical vein endothelial cells (HUVECs) during a hyperglycemic condition. Methods: HUVECs were cultured in normal glucose (5 mmol/L), and hyperglycemic (25 mmol/L) endothelial cell growth medium in the six well plates for 24 h. JSH-23 (30 μmol/L), as an inhibitor of NF-κB translocation to the nucleus, was added to the culture medium, 30 min before induction of hyperglycemia. Quantitative Real Time PCR was performed to measure the expression levels of miR-146a and mRNA NF-κB. NF-κB activity was measured by Elisa. Results: Hyperglycemia markedly increased the NF-κB activity and mRNA level in HUVECs. The expression of miR-146a significantly increased in hyperglycemic group compared to the normoglycemic group. On the other hand, JSH-23 prevented from miR-146a increment in hyperglycemic group and also it increased the mRNA expression level of NF-κB in this group. Conclusion: This result shows that NF-κB increases the gene expression of miRNA-146a in the early phase of hyperglycemia in HUVECs.