The Intervention Effect Of α-lipoic Acid On Indoxyl Sulfate-induced Damage In Human Umbilical Vein Endothelial Cells

Background Endothelial dysfunction and oxidative stress are major concern for patients with heart disease, and uremic toxin accumulation in chronic renal disease(CKD) is one of high-risk factor for heart disease. Indoxyl sulfate, one of the protein-bound uremic toxin, can not only show pro-oxidant effect but also induce endothelial dysfunction which will eventually develop into heart disease. Some antioxidant can improve endothelial dysfunction, and related researches gains much attention now.Objective This study aimed to investigate the effects of α-lipoic acid on antioxidant activity in indoxyl sulfate-induced endothelial cells and the possible mechanism, using human umbilical vein endothelial cells(HUVEC).Methods Choose HUVEC for cell culture, divide the cells into normal group, Indoxyl sulfate(IS) group and α-lipoic acid+Indoxyl sulfate(LA+IS) group. 3-nitro-l-tyrosine(3-NT) content was measured by ELISA, superoxide dismutase(SOD) activity was measured by xanthine method. Glutathione(GSH) content and oxide synthase(NOS) activity was measured by colorimetric method. Nitric oxide(NO) content in HUVEC was measured by nitric reductase method. Endothelial nitric oxide synthase(e NOS) expression was evaluated by RTFQ-PCR. All the data were analyzed by SPSS 17 software. Result were expressed as mean ± SD. Multiple comparisons were evaluated using one-factor ANOVA and means difference between two groups were analyzed by Bonferroni test.P value<0.05 was considered significant.Every experiment was performed more than four times.Results 1 oxidative stress indicators in endothelial cells ① Compared to that in control group(78.426±2.543mg/l), the concentration of GSH was lower in IS group(54.683±3.408mg/l)( P<0.001)and higher in IS+LA group(81.348±3.254mg/l) even compared with IS group(54.683±3.408mg/l)(P<0.001). ②Compared to that in control group(18.186±2.106U/mgprot), the activity of SOD in endothelial cells was lower in IS group(12.984±1.413U/mgprot)( P<0.001) and higher in IS+LA group(16.806±1.237U/mgprot) even compared with IS group(12.984±1.413U/mgprot)(P<0.001). 2 NO indicators in endothelial cells ① Compared to that in control group(48.235±2.508umol/l), the concentration of NO was lower in IS group(35.618±3.843umol/l)(P<0.001)and it’s higher in both LA group(52.329±2.935umol/l)and IS+LA group(42.565±3.273umol/l)(P<0.001) than that in IS group. ②Compared to that in control group(0.967±0.032U/L) and IS+LA group(0.902±0.064U/L), the activity of NOS was lower in IS group(0.835±0.057U/L)(P<0.001),(P<0.05). ③ Compared to that in control group(38.175±5.403nmol/l), 3-NT concentration was higher in IS group(47.665±4.934nmol/l)(P<0.001), even when compared with IS+LA group(35.661±4.726nmol/l)(P<0.001). ④Compared to that in control group(1.091±0.064), the e NOS expression was significantly lower in IS group(1.054±0.092)(P<0.05). Pretreatment with LA, the e NOS expression was increased in IS+LA group(1.096±0.073)( P<0.05).Conclusions 1 Indoxyl sulfate could induce oxidative damage in endothelial cells. 2 α-lipoic acid could ameliorate the oxidative damage induced by indoxyl sulfate by redress the e NOS uncoupling and eliminate the ROS in HUVECs.