Human mesangial cells resist glycoxidative stress through an antioxidant response

Abstract

The generation of advanced glycation end-products (AGE), the interaction with their receptors, the generation of reactive oxygen species, and the modulation of intracellular redox equilibrium are believed to be the main factors causing alterations of mesangial cell physiology leading to diabetic nephropathy. Normal human primary mesangial cells were exposed to glycoxidative stress by culture in high glucose (HG) or treatment with AGE for up to 6 days. In both cases only a moderate generation of reactive oxygen species and production of HNE-protein adducts were induced while protein nitrotyrosination was not affected. Moreover, HG and AGE caused a significant antioxidant response, confirmed by the induction of heme oxygenase 1 and the consumption of vitamin E. Glutathione was decreased only by HG. Mesangial cell proliferation and viability were slightly affected by HG and AGE. Furthermore, both treatments failed to influence TGF-ß1 and MCP-1 secretion and to modulate RAGE and collagen IV expression. We believe that normal human mesangial cells can resist glycoxidative stress by the observed antioxidant response. These results support the concept that mesangial cells are only partly responsible for the onset and progression of diabetic nephropathy and that the role of other cell types, such as podocytes and endothelial cells, should be taken into consideration.