Renal complications of aldosteronism and diabetes: role of oxidative stress and protective effects of polyphenol extract
Eglantine Elowe-Gruau1, Stéphanie Dal-Ros1, Nathalie Auberval1, Elodie Seyfritz1, William Bietiger1, Michel Pinget1,2, Nathalie Jeandidier1 & Séverine Sigrist1
Hyperaldosteronism and diabetes are two providers of kidney disease, showing molecular and cellular mechanisms in common, such as oxidative stress, causing renal tubular damages. The objective of this study is to evaluate in vitro the protective effect of a natural antioxidant (red wine polyphenols and green tea extract) in the onset of renal dysfunction. Hyperglycemia and hyperaldosteronism are induced respectively by increasing doses of glucose and aldosterone in primary cultures of rat renal proximal tubular cells (PCPR), and associated with a progressive loss of viability and apoptosis (quantified by Cell Titer and flow cytometry). In fact, the viability of PCPR in the presence of 6 g/l of glucose or 10−4 M of aldosterone is respectively 68.1 and 67.9%; 20.1 vs 8.9% and 45.7 vs 30.3% for apoptosis. Moreover, green tea extract (pre-incubated 1 h) is able to normalize viability (102.8 and 128%) and reduce apoptosis (10 and 18.2%) whereas red wine polyphenols have no effect. The expression of two antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD), is assessed by western blot. Expression of SOD is maintained (98%) whereas CAT is upregulated with hyperglycemia (280%). With hyperaldosteronism, CAT (345%) and SOD (122%) are upregulated. Finally, red wine polyphenols are able to overexpressed CAT (980 and 125%) and SOD (841 and 219%) respectively with hyperglycemia and hyperaldosteronism. This study suggests that polyphenols extract could be considered as an antioxidant prophylactic treatment of renal failure in patients suffering from aldosteronism or diabetes.