Hormone replacement therapy increases levels of antibodies against heat shock protein 65 and certain species of oxidized low density lipoprotein

Hormone replacement therapy (HRT) reduces cardiovascular risks, although the initiation of therapy may be associated with transient adverse ischemic and thrombotic events. Antibodies against heat shock protein (Hsp) and oxidized low density lipoprotein (LDL) have been found in atherosclerotic lesions and plasma of patients with coronary artery disease and may play an important role in the pathogenesis of atherosclerosis. The aim of the present study was to assess the effects of HRT on the immune response by measuring plasma levels of antibodies against Hsp 65 and LDL with a low and high degree of copper-mediated oxidative modification of 20 postmenopausal women before and 90 days after receiving orally 0.625 mg equine conjugate estrogen plus 2.5 mg medroxyprogesterone acetate per day. HRT significantly increased antibodies against Hsp 65 (0.316 ± 0.03 vs 0.558 ± 0.11) and against LDL with a low degree of oxidative modification (0.100 ± 0.01 vs 0.217 ± 0.02) (P<0.05 and P<0.001, respectively, ANOVA). The hormone-mediated immune response may trigger an inflammatory response within the vessel wall and potentially increase plaque burden. Whether or not this immune response is temporary or sustained and deleterious requires further investigation

Balloon-induced endothelial denudation promotes deep injury of the arterial wall

To investigate the cellular reactions to arterial injuries and the influence of a cholesterol-rich diet, 18 rabbits underwent endothelial denudation of the abdominal aorta with a balloon catheter. Fourteen animals were fed a 2% cholesterol diet and 4 were fed normal rabbit chow for 8 weeks. In the cholesterolfed group, 6 animals had only the expected intimal lesions; however, 8 animals exhibited different degrees of balloon=induced medial layer injury, with fibrous healing. Similarly, in the control rabbits, 1 had intimal lesions and 3 had both intimal and medial layer lesions. We conclude that removal of the endothelium with a balloon catheter prometes arterial wall injury deeper than expected. This unexpected result could influence the effect of interventions usually employed in experimental atherosclerosis