Autoantibodies against oxidized low-density lipoprotein and C-reactive protein are associated with diabetes and myocardial infarction in women

Abstract

Women with diabetes mellitus are at high risk of myocardial infarction (MI), and it is well recognized that smoking, hypertension, hyperlipidaemia and the diabetic state itself do not fully explain this increased risk. During the last decade, growing evidence has accumulated that the immune system, with oxidized low-density lipoprotein (LDL) as a key antigen, plays an important role in the development of atherosclerosis. The aim of the present study was to explore the association between the immune response, as measured by antibody titres to malondialdehyde-treated LDL (MDA-LDL) and levels of C-reactive protein (CRP; a marker of inflammation), and diabetes mellitus and MI in women. Women (35-64 years) with diabetes (n=18) and non-diabetic women (n=46) who had been treated in hospital for MI were compared with diabetic women without MI (n=35) and healthy controls (n=70). Blood samples were collected after an overnight fast. CRP was determined with a highly sensitive immuno-enzymometric assay. IgM and IgG antibodies against MDA-LDL were analysed with a solid-phase ELISA technique. Women with diabetes but without previous MI were more similar to women with previous MI (both with and without diabetes) than to the healthy controls. Compared with healthy women, the women with diabetes and/or MI had higher IgG (P<0.05) and lower IgM (P=0.006) antibody titres against oxidized LDL and higher CRP levels (P<0.001), associations that were independent of other cardiovascular risk factors. These findings might indicate a differentiated immune response against modified LDL, more pronounced inflammation and a more aggressive atherosclerotic process in women with diabetes.