Plasma levels of antibodies against oxidized LDL are inherited but not associated with HDL-cholesterol level in families with early coronary heart disease

Abstract

Objective: Oxidized low-density lipoproteins (oxLDL) and antibodies against them (anti-oxLDLs) are thought to play a central role in atherosclerosis. One proposed antiatherosclerotic mechanism for HDL is to prevent oxidation of LDL. This study examined whether plasma HDL-cholesterol (HDL-C) is related to plasma anti-oxLDL levels.

Methods: We collected families based on probands with low HDL-C and premature coronary heart disease (CHD). Antibody levels were determined in samples from 405 subjects. Immunoglobulin G, M and A levels against two in vitro models of oxLDL, malondialdehyde-acetaldehyde-modified LDL (MAA-LDL) and copper oxidized LDL (CuOx-LDL), were measured by ELISA. We carried out heritability estimation of antibody traits and bivariate analyses between HDL-C, LDL-C and antibody traits.

Results: All the antibody levels were significantly inherited (p < 0.001), heritability estimates ranging from 0.28 to 0.65. HDL-C exhibited no environmental or genetic cross-correlations with antibody levels. Significant environmental correlations were detected between LDL-C and both IgG levels (ρ(E) = 0.40, p = 0.046 and ρ(E) = 0.39, p < 0.001). There were no differences in antibody levels between subjects with normal and low HDL-C, or between CHD-affected and non-affected subjects.

Conclusion: In this study, low HDL-C level displayed no significant associations with the anti-oxLDL levels measured. The heritability of the anti-oxLDL levels was a novel and interesting finding.