Fenofibrate inhibits production of reactive oxygen species and oncofetal fibronectin induced by short-term intermittent high glucose through blockade of local aldosterone system in human mesangial cells / 中华内分泌代谢杂志

ABSTRACT

Objective To investigate the role of local aldosterone system in oncofetal fibronectin ( oncofetal FN) mRNA expression and reactive oxygen species (ROS) production in human mesangial cells (HMCs) exposed to short-term intermittent high glucose and the effect of Fenofibrate.Methods The HMCs were divided into 8 groupsnormal glucose(NG) ;osmotic fluctuation(OF) ;mean glucose load (MGL) ;stable high glucose (SHG),short-term intermittent high glucose (IHG) ; intermittent high glucose plus eplerenone (IHGE) ; intermittent high glucose plus fenofibrate(IHGF) ; and normal glucose plus fenofibrate (NGF) groups.The mRNA expression levels of Aldosterone synthase ( CYP11 B2 ),11 β-hydroxysteroid dehydrogenase type 2 ( 11βHSD2 ) and oncofetal FN were determined by RT-PCR.The expression of CYP11B2 protein was determined by western-blot.Aldosterone level in cell culture supernatant was detected by radioimmunoassay.The expression and translocation of mineralocorticoid receptor (MR)protein were assayed with confocal laser scanning microscopy. ROS levels were determined by Fluorescence microscopy and fluorescence microplate reader.Results ( 1 ) MGL,SHG,and IHG groups showed a 2.41,3.63,and 4.45 times increase in CYP11B2 mRNA expression,and a 1.83,2.15,and 2.78 times increase in CYP11B2 protein expression,respectively,compared with NG group (P ＜ 0.05 ).The aldosterone levels of HMCs culture supernatant in MGL,SHG,and IHG groups were also increased,being 1.49,2.04,and 2.54 times of that in NG group ( P＜0.05 ),and the degree of elevation in IHG group was more marked than that in SHG group( P＜0.05 ).MR was activated and translocated from cytosol to nucleus in MGL,SHG,and IHG groups.Quantitative analysis showed the ratioes of cytosol/nucleus fluorescence intensity in MGL,SHG,and IHG groups were 15％,38％,and 53％ decreased as compared with that in NG group,and the decrease was more marked in IHG group ( P＜0.05 ).(2) Oncofetal FN mRNA expression and ROS levels in MGL,SHG,and IHG groups were increased,being 1.54,2.31,3.65 and 1.26,1.91,2.48 times of those in NG group,respectively ( P＜0.05 ),and this increase was more marked in group IHG ( P＜O.05 ).Compared with IHG group,oncofetal FN mRNA expression and ROS levels in group IHGE were significantly decreased by 54％ and 53％,and in group IHGF by 45％ and 39％. ( 3 ) CYP11B2 mRNA,protein,and aldosterone levels in IHGF group were decreased by 74％,59％,and 50％,and the activation of MR in group IHGF was inhibited when the ratio of cytosol/nuclear fluorescence intensity was increased 1.88 fold as compared with that in group IHG ( P＜0.05 ).Conclusions Increased expressions of oncofetal FN and ROS by HMCs induced by short-term intermittent high glucose were nore marked than those induced by stable high glucose.The mechanism was associated with activation of local aldosterone system.Fenofibrate may inhibit the activation of local aldosterone system and alleviate the injury to HMCs induced by intermittent high glucose.