Abstract
A characteristic of atherosclerosis is the accumulation of large amount of lipids, mainly cholesteryl ester, in arterial walls. These lipids accumulate in the extracellular space or in the cytoplasm of lipidladen cells. To understand mechanisms by which these lipids accumulate in arterial walls, we prepared a novel monoclonal antibody (ASH1a/256C) which recognized the region of fatty streaks in atherosclerotic aortae both in human and WHHL rabbits. The antibody recognized especially the surface area of fatty streaks, suggesting that the antigenic material was associated with the endotherial cells located on the fatty streaks. The amount of antigenic material detected by ELISA was almost 8 times higher in atherosclerotic aorta than in normal aorta. Since the antigenic material was extracted by acetone and was presumed to be a glycolipid, reactivity of the antibody to various gangliosides and related compounds was examined. The antibody reacted strongly with asialo GM2 and less with asialo GM1. The reactivity to asialo GM2 was 5 times higher than to asialo GM1. The antibody, however, did not react with other gangliosides such as GMI-4, GD1a, GT1b and lactosyl ceramide. Gangliosides of globo family, mono and polysaccharides, heparan sulfate, chondroitin sulfate had no reactivity either. To examine that the antigenic material in atherosclerotic lesions was asialo GM2 itself or similar compounds, the acetone extract prepared from the lesions was applied an a slica gel TLC and immunostaining was carried out. The antibody reacted with four compounds, one of which corresponded to asialo GM2, suggesting that atherosclerotic lesions contain asialo GM2 itself and three novel compounds which possess similar epitope of asialo GM2.
We have also produced a monoclonal antibody (EMR1a/212D) which specifically recognizes the extracellular regions where lipids deposit in atherosclerotic aorta. The antigenic material of this antibody was revealed to be vitronectin, a 66kDa glycoprotein. To investigate molecular species of vitronectin in atherosclerotic lesions, a new monoclonal antibody (EMR1b/244H) which recognized peptide region of vitronectin was prepared. Using the both antibodies, 56, 50 and 47kDa vitronections were found in atherosclerotic lesions together with 66kDa vitronectin which is a major component in serum. The 56 and 50kDa vitronectin were major component in atherosclerotic lesions and increased markedly with developmant of atherosclerosis.
Based on our findings, we will discuss roles of endotherial cells and vitronectin in accumulation of lipids in arterial walls.
