Local aldosterone system mediated "hyperglycaemic memory" in human mesangial cells

Objective To investigate the effect of hyperglycaemic memory on the local aldosterone system,reactive oxygen species(ROS) and expression of oncofetal fibronectin(oncofetal FN) mRNA in human mesangial cells(HMCs),and to further understand the role of local aldosterone system in the process.Methods In this study HMCs were divided into the following groups:normal glucose group(NG,5 mmol/L D-glucose for 2 days),high glucose group(HG,25 mmol/L D-glucose for 2 days),memory group(M,25 mmol/L D-glucose for 2 days→5 mmol/L D-glucose for 4 days),memory+eplerenone group(MY,25 mmol/L D-glucose for 2 days→5 mmol/L D-glucose+10 μmol/L eplerenone for 4 days),normal glucose+eplerenone group(NY,5 mmol/L D-glucose for 2 days→5 mmol/L D-glucose+10 μmol/L eplerenone for 4 days),and persistent normal glucose group(SN,5 mmol/L D-glucose for 6 days).ROS levels were tested by fluorescence microscope and fluorescence microplate reader.Aldosterone synthase(CYP11B2) protein expression was detected by Western blotting analysis.The mRNA expressions of 11β-hydroxysteroid dehydrogenase type 2,CYP11B2 and oncofetal FN were detected by RT-PCR.The expression and translocation of mineralocorticoid receptor(MR) was observed by laser scanning confocal microscope(LSCM).Aldosterone level in cell culture supernatant was detected by radioimmunoassay.Results(1)CYP11B2 mRNA and protein expression in group HG and in group M were all significantly increased,being 3.45,2.09 and 3.14,2.06 folds of those in group NG,respectively(all P0.05).The aldosterone levels in HMCs culture supernatant were significantly increased in group HG and group M,being 2.01 and 1.81 folds of that in group NG,respectively(P0.05).MR was activated and translocated from the cytosol to the nucleus in group HG and group M.Quantitative analysis showed that the ratios of cytosol/nucleus fluorescence intensity in group HG and group M were decreased by 30% and 21% compared with that in group NG,respectively(all P0.05).(2)Oncofetal FN mRNA expression and ROS levels in group HG and group M were significantly increased,being 2.23,1.99 and 2.16,1.90 folds those of group NG,respectively(all P0.05).Oncofetal FN mRNA expression and ROS levels in group MY were significantly decreased,being 35% and 51% of those in group M(all P0.05).Conclusion HMCs have hyperglycaemic memory effect,which might be mediated by the local aldosterone system.