Experimental Induction of Atheroarteriosclerosis by the synergy of Allergic Injury to Arteries and Lipid-Rich Diet: III. The Role of Earlier Acquired Fibromuscular Intimal Thickening in the Pathogenesis of Later Developing Atherosclerosis

Clinicopathologic evidence suggests that diffuse intimal thickening, a type of arteriosclerosis without manifest lipid deposit, may predispose to later developing atherosclerosis in man. This hypothesis was tested in the following experiments. Injury to coronary arteries of rabbits was induced by immunologic means, and arterial lesions were allowed to heal for many weeks. One group of animals was then sacrificed, and in their coronary arteries were found numerous fibromuscular intimal lesions closely resembling diffuse intimal thickening in man. The remaining rabbits were fed a cholesterol-supplemented diet for 80 days and then sacrificed. Fibromuscular intimal lesions of coronary arteries were found in these rabbits also. However, approximately two-thirds of these lesions were found to contain lipid, and many closely resembled coronary atherosclerosis in man. Further analysis of the data indicates that the atherosclerotic lesions in the rabbits evolved from immunologically induced fibromuscular intimal lesions which later and preferentially accumulated lipid in the presence of hypercholesterolemia. Results of these experiments suggest that in man fibromuscular intimal lesions, and in particular diffuse intimal thickening, acquired earlier in life can later accumulate lipid preferentially and thus redispose to atherosclerosis.