The association of C-reactive protein with an oxidative metabolite of LDL and its implication in atherosclerosis

C-reactive protein (CRP) is one of the strongest independent predictors of cardiovascular disease. We have previously reported that oxidized LDL (oxLDL) interacts with β2-glycoprotein I (β2GPI), implicating oxLDL/β2GPI complexes as putative autoantigens in autoimmune-mediated atherosclerotic vascular disease. In this study, we investigated the interaction of CRP with oxLDL/β2GPI complexes and its association with atherosclerosis in patients with diabetes mellitus (DM). CRP/oxLDL/β2GPI complexes were predominantly found in sera of DM patients with atherosclerosis. In contrast, noncomplexed CRP isoforms were present in sera of patients with acute/chronic inflammation, i.e., various pyrogenic diseases, rheumatoid arthritis (RA), and DM. Immunohistochemistry staining colocalized CRP and β2GPI together with oxLDL in carotid artery plaques but not in synovial tissue from RA patients, strongly suggesting that complex formation occurs during the development of atherosclerosis. Serum levels of CRP correlated with soluble forms of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, and oxLDL/β2GPI complexes correlated with total cholesterol and hemoglobin A1c. Thus, the generation of CRP/oxLDL/β2GPI complexes seems to be associated with arterial inflammation, hyperglycemia, and hypercholesterolemia. CRP/oxLDL/β2GPI complexes can be distinguished from pyrogenic noncomplexed CRP isoforms and may represent a more specific and predictive marker for atherosclerosis.