The relationship between apolipoprotein E and serum oxidation related variables is apolipoprotein E phenotype dependent

To examine the relationship between apolipoprotein E and serum oxidation status, we assayed apolipoprotein E level, apolipoprotein E phenotype, and levels of lipid peroxides and transition metal ions and their binding proteins in sera from apparently healthy individuals. The study group included 129 women aged 22-63 years and 53 men aged 22-56 years. Among subjects with apolipoprotein E 4/3 phenotype, lipid peroxide levels were higher compared with E 3/2 phenotype (786+/-182 nmol/l vs. 659+/-174 nmol/l, P=0.015), and ceruloplasmin levels were slightly higher compared with apolipoprotein E 3/3 phenotype (0.28+/-0.08 mg/l vs. 0.26+/-0.06 mg/l, P=0.035). In the study group as a whole, there were significant associations between serum apolipoprotein E level, and serum levels of ceruloplasmin (r=0.266, P<0.001) and ferritin (r=0.2, P<0.007). Among subjects with apolipoprotein E 4/3 phenotype, there was a significant association between serum apolipoprotein E and lipid peroxide levels (r=0.470, P<0.01), which was not apparent among subjects with E 3/3 or E 3/2 phenotypes. In multivariate analysis, apolipoprotein E phenotype was a small but significant independent contributor to variation in serum lipid peroxide levels. These data suggest that there may be heterogeneity among apolipoprotein E phenotypes in their relationships with serum lipid oxidation status.