Glucose-induced oxidative stress in mesangial cells

Glucose-induced oxidative stress in mesangial cells.BackgroundHyperglycemia is a well-recognized pathogenic factor of long-term complications in diabetes mellitus. Hyperglycemia not only generates reactive oxygen species but also attenuates antioxidant mechanisms creating a state of oxidative stress.MethodsPorcine mesangial cells were cultured in high glucose (HG) for ten days to investigate the effects on the antioxidant defenses of the cell.ResultsMesangial cells cultured in HG conditions had significantly reduced levels of glutathione (GSH) compared with those grown in normal glucose (NG). The reduced GSH levels were accompanied by decreased gene expression of both subunits of γ-glutamylcysteine synthetase (γ-GCS), the rate-limiting enzyme in de novo synthesis of GSH. Elevated levels of intracellular malondialdehyde (MDA) were found in cells exposed to HG conditions. HG also caused elevated mRNA levels of the antioxidant enzymes CuZn superoxide dismutase (SOD) and MnSOD. These changes were accompanied by increased mRNA levels of extracellular matrix proteins (ECM), fibronectin (FN) and collagen IV (CIV). Addition of antioxidants to high glucose caused a significant reversal of FN and CIV gene expression; α-lipoic acid also up-regulated γ-GCS gene expression and restored intracellular GSH and MDA levels.ConclusionsThe results demonstrate the existence of glucose-induced oxidative stress in mesangial cells as evidenced by elevated MDA and decreased GSH levels. The decreased levels of GSH are as a result of decreased mRNA expression of γ-GCS within the cell. Antioxidants caused a significant reversal of FN and CIV gene expression, suggesting an etiological link between oxidative stress and increased ECM protein synthesis