Effects of hemodialysis and vitamin E supplementation on low-density lipoprotein oxidizability in end-stage renal failure

Abstract

Cardiovascular diseases represent the major cause of mortality in hemodialysis (HD) patients. HD increases oxidative stress and oxidation of low-density lipoprotein (LDL) is a crucial step in the development of atherosclerosis. Vitamin E has been shown to reduce LDL oxidation. Our aim was to test the effect of a single HD session and chronic vitamin E supplementation on LDL oxidizability in HD patients. LDL susceptibility to copper-induced oxidation (lag-phase, LP) was measured in 19 HD patients, both immediately before and after hemodialysis; 18 age-matched healthy subjects served as controls. Both pre-HD and post-HD measurements were repeated after 12 weeks of vitamin E supplementation (800 IU/day) in a placebo-controlled, randomized design. At baseline, HD patients showed hypertriglyceridemia, a significant triglyceride enrichment in LDL and HDL and an enhanced LDL resistance to oxidation (186 ± 6 vs. 163 ± 4 min, p<0.003). A single HD session decreased (to 172 ± 6 min, or -8%, p<0.002), and chronic vitamin E administration increased, LDL resistance to oxidation (+19%, p = 0.002 vs. placebo) without changing the serum lipid profile or lipoprotein lipid composition. We conclude that in patients on chronic hemodialysis, hypertriglyceridemia and triglyceride enrichment of LDL and HDL particles are associated with increased resistance of LDL to in vitro oxidation despite the fact that each dialysis session acutely increases LDL oxidizability. Vitamin E supplementation improves LDL resistance to oxidation without modifying circulating lipid levels and partitioning.