Low-density lipoprotein oxidation and antioxidized LDL antibodies in peritoneal dialysis patients

Due to the potential atherogenic effects of oxidized low-density lipoproteins (LDLs), LDL oxidation was studied in a group of uremic patients on chronic peritoneal dialysis. The results were compared with those obtained in a group of 70 controls, 10 uremic patients on predialytic conservative therapy, and 11 patients on repetitive hemodialysis. LDL oxidation was evaluated in all subjects as the susceptibility to in vitro oxidation (monitoring the resistance to Cu(2+)-induced formation of conjugated dienes, lag-phase minutes) and the presence of plasma antioxidized LDL antibodies, expressed as the ratio anti-ox-LDL/antinative LDL antibodies. Vitamin E (main antioxidant agent) content in LDLs was also measured and the lipid profile studied. No significant changes in vitamin E concentration were found, although LDLs from uremic patients appeared more susceptible to in vitro and in vivo oxidation (as demonstrated by an earlier production of conjugated dienes and by the presence of a higher antibody ratio), as compared to control subjects. Analysis of the different groups of uremic patients revealed that peritoneal dialysis, not hemodialysis, significantly ameliorated the oxidation markers. However, prolonged treatment with peritoneal dialysis caused a decrease in vitamin E concentration in LDLs and increased their susceptibility to oxidation.