Comparative studies on the antagonism of proliferation and atrophy in atherosclerosis

Proliferation, atrophy and lipoprotein catabolism are nodal points in an intricate network of pathogenetic factors which influence the complex morphogenesis of atherosclerosis with its ambiguous phenotypes. The compiled findings of our group show that leiomuscular atrophy of the arterial media represents a hitherto widely ignored pathogenetic hinge in atherogenesis which is expected to impede intramural transport of low density lipoproteins (LDL), contributes to the formation of atheromatous plaques due to chemical modification of stagnant LDL, and influences the topographic distribution of plaques. Contrary to the age-dependent atrophy seen in the smooth muscle cells of the tunica media, myointimal cells of the intima, the so-called Langhans cells, are prone to proliferation. In part, cellular growth in atherosclerotic lesions seems to be triggered by biosynthesis of endothelin-1 by lipid-storing macrophages. Similar to self-limited tumour growth, proliferation of atherosclerotic lesions in their cellular phase are controlled by p53, P21 and the gene products of MDM2, Bcl-2 and Bax. Apoptotic cell loss eventually leads to fibrotic end stage lesions.