The Protein and Lipid Composition of Arterial Elastin and Its Relationship to Lipid Accumulation in the Atherosclerotic Plaque

Abstract

A B S T R A C T Elastin preparations from intimal layers and the media of normal and atherosclerotic human aortae were analyzed for protein and lipid content. In atherosclerotic aortae, elastin from plaques was compared with elastin from adjacent normal appearing areas of the same aorta.Arterial elastin purified by alkaline extraction appeared to be a protein-lipid complex containing free and ester cholesterol, phospholipids, and triglycerides. The lipid component of normal arterial elastin was small (1-2%). With increasing severity of atherosclerosis, there was a progressive accumulation of lipid in intimal elastin from plaques, reaching a mean lipid content of 37% in severe plaques. The increase in the lipid content of plaque elastin preparations wvas mainly due to large increases in cholesterol, over 80% of which was cholesteryl ester. This deposition of cholesterol in plaque elastin accounted for 20-34% of the total cholesterol content of the plaque. The increased lipid deposition in plaque elastin was associated with alterations in the amino acid composition of plaque elastin. In elastin from plaque intima, the following polar amino acids were increased significantly: aspartic acid, threonine, serine, glutamic acid, lysine, histidine, and arginine; whereas, cross-linking amino acids: desmosine, isodesmosine, and lysinonorleucine were decreased significantly. The amino acid and lipid composition of elastin from normal appearing aortic areas was comparable to that of normal arterial elastin except for intimal elastin directly adjacent to and medial elastin directly below the most severe plaques.

The Interaction of Serum and Arterial Lipoproteins with Elastin of the Arterial Intima and Its Role in the Lipid Accumulation in Atherosclerotic Plaques

“…The striking increase in lipid content, particularly of ester cholesterol, as well as the increase in polar amino acids and the reduction in cross-linking amino acids observed in the alkali-extracted elastin of grade I and grade II plaques, are in agreement with previous observations (11). The differences in the amino acid composition involve amino acids which represent relatively small components of the isolated elastin preparations.…”

“…Recent biochemical analyses of arterial elastin preparations have shown that the lipids accumulating on elastic membranes of atherosclerotic lesions are associated with the elastin protein of these elastic membranes, even in early atherosclerosis (11). The arterial elastin preparations were defined as that protein material which remained undegraded after alkali hydrolysis of arterial tissue homogenates.…”

The Inhibitory Effect of Cacao Liquor Crude Polyphenols(CLP) on Experimental Arteriosclerosis with Calcification in Rat Soft Tissue.

“…The lipid and mineral depositions in the aorta and aortic elastin fr. were similar to those in human atherosclerosis as described by Kramsch et al 13) Recently, Bennani-Kabchi et al 14) reported that vitamin D 2 and a high Ch diet administration induced advanced atherosclerotic lesions in the arterial wall with elevated oxidized LDL and calcification. These authors estimated that deposition of Ch, Ca and P in the aorta was affected by increases in lipid peroxides produced by vitamin D 2 , a vitamin E deficiency, and the atherogenic diet.…”

Quantitative ultrastructural analysis of perifibrous lipid and its association with elastin in nonatherosclerotic human aorta.

“…Furthermore, elastase treatment was found to release considerable quantities of cholesterol from normal aortic intima and atherosclerotic plaque. Kramsch and Hollander 19 and others 2122 found that large amounts of cholesterol derived from LDL bind to elastin after a relatively brief (24-hour) incubation. Noma and colleagues 21 extended this work by demonstrating immunologically the presence of apoprotein B on the surface of LDL-incubated elastin.…”