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

Figure 12  Inhibitory effects of metformin on rat mesangial cells. A-C: Protein bands and protein expression of tenascin-C (TNC) and phosphorylated nuclear factor-κB p65 (Ser536) (p-NF-κB p65). The MET (5.5 mmol/L glucose + 10 μmol/L metformin), 24H (30 mmol/L glucose), H+1 (30 mmol/L glucose + 1 μmol/L metformin), H+5 (30 mmol/L glucose + 5 μmol/L metformin), H+10 (30 mmol/L glucose + 10 μmol/L metformin), H+20 (30 mmol/L glucose + 20 μmol/L metformin), and H+50 (30 mmol/L glucose + 50 μmol/L metformin) groups were cultured with the appropriate medium for 24 h. ^aP < 0.05 compared with rat mesangial cells (RMCs) cultured with normal glucose concentrations; ^cP < 0.05 compared with RMCs cultured with high glucose concentrations; D-F: Protein bands and protein expression of connective tissue growth factor (CTGF) and fibronectin (FN). RMCs were divided into normal-glucose (NG, 5.5 mmol/L glucose), high-glucose (HG, 30 mmol/L glucose), and H+20 (30 mmol/L glucose + 20 μmol/L metformin) groups and cultured with the appropriate 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, p-NF-κB p65, and NF-κB p65 levels were detected using Western blot. The results are presented as the mean ± SD of six independent experiments after normalization to GAPDH levels. TNC: Tenascin-C; 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; H: High-glucose.