Dysregulation of miR-146a is associated with exacerbated inflammation, oxidative and endoplasmic reticulum stress in the progression of diabetic foot ulcer.

Abstract

Recent evidence has implicated the role of microRNA-146a (miR-146a) in regulating inflammatory responses. In the present study, we investigated the role of miRNA-146a in the progression of diabetic foot ulcer (DFU) in type 2 diabetes mellitus patients (T2DM) and studied its correlation with stress mediators such as Endoplasmic Reticulum (ER) and oxidative stress. Ninety subjects were enrolled and evenly distributed among three groups: Controls (n = 30), T2DM without complications (n = 30) and T2DM with foot ulcers (n = 30). Subsequently, each group was further subdivided based on the University of Texas classification. Peripheral blood was collected from all the study subjects, while tissue biopsies were taken only from DFU patients. Total RNA from both PBMCs and wound tissues were isolated using miRNA isolation kit and qPCR was performed to check the expression of miR-146a, ER stress and oxidative stress markers. Our findings revealed a significant decrease in miR-146a expression among T2DM patients with Grade 2 and Grade 3 DFUs compared with those with Grade 0 and Grade 1 DFUs. Notably, inflammatory genes regulated by miR-146a, including TRAF6, IRAK-1 and ADAM, were all upregulated in T2DM patients with Grade 2 and Grade 3 DFUs. Moreover, reduced miR-146a levels were correlated with increased markers of ER stress and oxidative stress in Grade 2 and Grade 3 DFU patients. Furthermore, our in vitro experiment using mouse 3T3 fibroblasts demonstrated a downregulation of miR-146a following induction of hyperglycaemia, ER stress and oxidative stress in these cells. These findings suggest a potential link between diminished miR-146a expression and heightened oxidative and ER stress in T2DM patients with more severe grades of DFUs. Our results imply that targeting miR-146a may hold therapeutic promise for managing disease progression in DFU patients, as it could help alleviate oxidative and ER stress associated with diabetic complications.