Histopathological and Ultrastructural Examinations of Rabbit Coronary Artery Vasculitis Caused by Bovine Serum Albumin: An Animal Model of Kawasaki Disease

Abstract

Objective: To observe the histopathological and ultrastructural features of coronary artery vasculitis in rabbits caused by repeated intravenous injections of bovine serum albumin (BSA), mimicking Kawasaki disease.Materials and Methods: Twenty weanling rabbits were randomly and equally divided into treatment groups for BSA or normal saline (NS), and administered the respective treatment by intravenous injection once every 12 days for two cycles. Six weeks after the first treatment, rabbits underwent coronary angiography and coronary arteries were removed within 1 h. Histopathological examination was performed by light, scanning electron, and transmission electron microscopy.Results: Coronary arteriography revealed that 3 rabbits (3/10) in the BSA group had various levels of dilation and narrowing of the left coronary arteries, while histological examination showed that 10 rabbits (10/10) had infiltration of the coronary arteries by inflammatory cells. Incomplete endothelium, breakage of elastic fiber, and intimal thickening were also observed in 8 rabbits (8/10) from the BSA group. Ultrastructurally, in 3 rabbits (3/10) in the BSA group, leukocyte migration, shedding of endothelial microparticles from the plasma membranes, incomplete endothelium, abscission of endothelial cells, breakage of the internal elastic lamina (IEL), degeneration of smooth muscle cells in the medial membrane, and swollen mitochondria were detected. By contrast, the IEL of the NS control group was continuous and of uniform thickness.Conclusion: This rabbit model of coronary arteritis displayed histopathological and ultrastructural features similar to those of Kawasaki disease in humans. Breakage of the IEL, a key factor in aneurysm formation, was observed in the coronary arteries. Therefore weanling rabbits may serve as an experimental model for immune complex vasculitis involving coronary arteries that mimics Kawasaki disease.