Abstract:

Abstract:Objective To investigate the effect of tannic acid on glomerular mesangial cells (GMC), and to clarify the mechanism of tannic acid in improving the pathological changes of diabetic nephropathy (DN) from the aspect of oxidative stress and micro-inflammation. Methods   The glomerular mesangial cells were treated with glucose (30 mmol/L) or  advanced glycosylation end-products (AGEs) bovine serum albumin(BSA) (250 mg/L) and then different concentrations of tannic acid (10, 20, 40 and 80 μmol/L) were added into the GMC. The cells cultured by normal glucose or treated with BSA were used as control groups and then the level of malonic dialdehyde(MDA）, glutathione peroxidase (GSH-Px ), superoxide Dismutase(SOD), CAT (Catalase) activities and   8-hydroxy-2′-deoxyguanosine(8-OHdG) levels in the culture supernatant 48 h after culture  were determined by colorimetry and ELISA method. The expressions of  intercellular cell adhesion molecule-1(ICAM-1)  protein,monocyte chemotactic protein 1(MCP-1) and  ICAM-1 mRNA in GMC  were detected by immunohistochemical staining and RT-PCR method. Results  Compared with high glucose and AGEs groups, the MDA levels in  tannic acid groups were reduced significantly（P<0.05）; the activities of GSH-Px,  SOD and CAT were increased significantly（P<0.05 or P<0.01）;the 8-OHdG levels in annic acid groups were significantly reduced （P<0.05）. Compared with  high glucose and AGEs groups, the expressions levels of ICAM-1  protein in 40 and 80 μmol/L tannic acid  groups were decreased(P<0.05). The mRNA expressions levels  of MCP-1 and ICAM-1 were significantly lower  than those in  high glucose group （P<0.01）.  Conclusion  Tannic acid could protect GMC against the damage of oxidative and inflammatory mediators, thereby delaying and improving the glomerular lesions of DN.

Key words:  tannic acid, diabetic nephropathy, oxidative stress, micro-inflammation, 8-hydroxy-2'-deoxyguanosine