Autoantibodies to oxidized low-density lipoprotein in patients with Type 2 diabetes mellitus

Background: Oxidation of low-density lipoprotein (LDL) is a crucial step in atherogenesis. There is an urgent need for direct measures of in vivo oxidative stress. Autoantibodies against oxidized low-density lipoprotein (Ab against Ox-LDL) are a direct measure of oxidative stress and predict cardiovascular disease. Our aim was to evaluate an ELISA for Ab against Ox-LDL in Type 2 diabetes, a condition with increased oxidative stress. Methods: Ab against Ox-LDL were measured by ELISA and expressed as a ratio of Ox-LDL to native LDL (N-LDL). Samples were obtained from 45 Type 2 diabetic patients and 25 matched controls before and after supplementation with alpha tocopherol (AT, 1200 IU/day). Results: The assay had good precision. While there was no interference with bilirubin and hemolysis, triglycerides 500 mg/dl increased antibody titer, which was abrogated by airfuging. Compared to controls, significantly increased titers of Ab against Ox-LDL were found in diabetics (diabetes mellitus Type 2) with macrovascular disease (DM2-MV), but not without macrovascular disease (DM2) (DM2: 1.32 ± 0.33; DM2-MV: 1.48 ± 0.44 vs. controls, 1.21 ± 0.28; p < 0.05). AT supplementation significantly decreased titers of Ab against Ox-LDL in both diabetic groups (p < 0.01). Conclusion: This assay may serve as a future test for the assessment of cardiovascular risk especially in patients with increased oxidative stress.