Modification of two types of cholesterol atherosclerosis in rabbits by blocking lipoprotein lysine ϵ-amino groups

Abstract

In previous studies, it was shown that a lysine deficient diet reduces the severity of aortic cholesterol atherosclerosis in rabbits. Feeding 1-amino-3-imino N,N′ propene diacetate (AIPD) produced 2 metabolic by products with active aldehyde groups 1-amino propenal acetic acid (APA) and malonyldialdehye (MDA) that transiently block the lysine ϵ-amino groups of all proteins and lipoproteins in vivo. This paper reports the effects of blocking the lysine free ϵ-amino groups of all lipoproteins on 2 different types of cholesterol atherosclerosis; (1) A proliferative-type cholesterol atherosclerosis containing a high proportion of spindle-shaped myogenic foam cells rich in collagen and alcian blue-stainable material produced by feeding a diet containing cholesterol, peanut oil, ethanol and butylated hydroxyanisole and (2) cholesterol atherosclerosis containing a high proportion of polyhedral-shaped non-myogenic macrophage-type foam cells produced by feeding cholesterol and oleic acid. After 14 weeks on the diets the mean±SD percent of intimal aortic area covered with the myogenic-type atherosclerosis in the control peanut oil-fed group was 34±6% and this was reduced to 13±3% in the peanut oil AIPD group. In contrast, after 14 weeks in the control oleic acid group the severity of atherosclerosis was 14±4% and this was increased to 36±7% in the oleic acid AIPD group. Aortic cholesterol concentration was decreased in the AIPD peanut oil group relative to its control group but was increased in the AIPD oleic acid group relative to its control group. A higher concentration of AIPD metabolites accumulated in the atherosclerotic lesions of the oleic AIPD group than in the peanut oil AIPD group indicating that a larger amount of lysine blocked lipoprotein accumulated in the macrophage-rich lesions of the oleic acid AIPD group than in the myogenic-rich lesions of the peanut oil AIPD group. Blocking lysine ϵ-amino groups in vivo by feeding AIPD did not modify DNA synthesis in the aortae of either AIPD group relative to their control groups.