Abnormal lipid metabolism and oxidative stress in hemodialysis patients

Abstract

Oxidative stress is enhanced in patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD). Bioincompatibility represents an important source of reactive oxygen species. HD patients exhibit altered antioxidative defenses, and antioxidative vitamins such as vitamin E and C are altered in uremia. Frequently, HD patients also suffer from atherosclerotic cardiac disease. We previously reported that low-density lipoprotein (LDL) of HD patients is rich in malondialdehyde (MDA), an end product of lipid peroxidation. MDA-rich LDL is thought to be an atherogenic lipoprotein because of its enhancement of macrophage foam-cell formation. We conducted a controlled study for 2 years comparing the effects of a vitamin E-coated cellulose membrane dialyzer and an ordinary cellulose membrane dialyzer on lipid metabolism and the progress of atherosclerosis. LDL MDA and oxidized LDL (ox-LDL) were measured in HD patients by using these two types of dialyzers. Plasma vitamin E and lipid concentrations were also evaluated. Aortic calcification index (ACI) was evaluated by CT scan to assess the progress of atherosclerosis before and every year after initiation of the treatment. The use of a vitamin E-coated cellulose membrane dialyzer for 6 months, 1 year, and 2 years resulted in a significant reduction in LDL-MDA and ox-LDL compared with that obtainal with the use of the ordinary cellulose membrane dialyzer. The treatment with a vitamin E-coated dialyzer significantly reduced the percent increase in ACI after 24 months as compared with control. There were no significant differences in plasma vitamin E and lipid concentrations between the two groups. These results suggest that oxidative stress could be one of the factors stimulating abnormal lipid metabolism and atherosclerosis in ESRD patients.