Metformin regulates inflammation and fibrosis in diabetic kidney disease through TNC/TLR4/NF-κB/miR-155-5p inflammatory loop

Figure 10  Inhibition of miR-155-5p expression. A: Protein bands; B-F: Protein expression of tenascin-C (TNC), Toll-like receptor-4 (TLR4), phosphorylated nuclear factor-κB p65 (Ser536) (p-NF-κB p65), connective tissue growth factor (CTGF), and fibronectin (FN). Rat mesangial cells (RMCs) were transfected with a miR-155-5p inhibitor to inhibit the expression of miR-155-5p (IN) or non-specific inhibitor (IN-NC) for 6 h and further cultured with normal glucose or high glucose concentrations for 24 h. The inhibition of miR-155-5p reduced the levels of TNC, TLR4, fibrosis factors (CTGF and FN), and p-NF-κB p65. RMCs were transfected with siRNA-IN to inhibit miR-155-5p and siRNA-NC for 6 h, and the media were then replaced with normal-glucose (NG, 5.5 mmol/L glucose) or high-glucose (HG, 30 mmol/L glucose) medium for 24 h. ^aP < 0.05 compared with RMCs cultured with normal glucose concentrations; ^cP < 0.05 compared with RMCs cultured with high glucose concentrations. TNC, TLR4, p-NF-κB p65, NF-κB p65, CTGF, and FN levels were all detected using Western blot. The results are presented as the mean ± SD of six independent experiments after normalization to GAPDH levels. TNC: Tenascin-C; TLR4: Toll-like receptor-4; p-NF-κB p65: Phosphorylated nuclear factor-κB p65 (Ser536); NF-κB p65: Nuclear factor-κB p65; CTGF: Connective tissue growth factor; FN; Fibronectin; N: Normal control; NC: Negative control; H: High-glucose.