Relationship between lipoprotein- and oxidation-related variables and atheroma lipid composition in subjects undergoing coronary artery bypass graft surgery

The relationship between atheroma lipid composition and serum lipoprotein a nd oxidation measurements has not been fully explored. To address this ques tion, we studied serum, plasma, and aortic wall specimens from 66 subjects undergoing coronary artery bypass graft surgery. The lipid composition of a ortic specimens was characterized in terms of cholesterol ester and cholest erol crystal plus phospholipid by using hot-stage polarizing light microsco py; tissue oxidation status was assessed by measuring conjugated dienes. Se rum lipoprotein-related measurements included total cholesterol, triglyceri de, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HD L) cholesterol, apolipoproteins B and AI, and Lipoprotein(a). Oxidation sta tus was assessed by measuring LDL mobility, thiobarbituric acid-reactive su bstances, LDL conjugated dienes, and IgG and IgM autoantibodies against oxi dized LDL. Fasting blood glucose was also determined. Lesion cholesterol cr ystal plus phospholipid content was associated inversely with serum HDL cho lesterol levels (r=-0.279, P=0.029) and positively with fasting blood gluco se (r=0.359, P=0.016), LDL mobility (0.276, P<0.05), and IgM autoantibodies against oxidized LDL (r=0.272, P=0.037). There was also a significant rela tionship between the level of aortic tissue conjugated dienes and plasma LD L mobility (r=0.332, P=0.007). In multivariate analysis, IgM autoantibodies against oxidized LDL, fasting blood glucose, and LDL mobility, in descendi ng order of significance, together accounted for 35% of the variability in aortic lesion cholesterol crystal plus phospholipid content. These data sup port direct and independent roles for oxidation and hyperglycemia in the pa thophysiology of atherosclerosis.