M1 macrophage is the predominant phenotype in coronary artery lesions following Kawasaki disease.

Kawasaki disease (KD) is a systemic inflammatory process that affects the medium-sized arteries, causing various cardiovascular complications. However, it is not clear if the vascular sequelae following KD can predispose to the development of atherosclerosis later in life. Our aim was to examine the macrophage phenotypes in the coronary arteries forming giant aneurysms after KD to gain insight into the pathogenesis of vascular lesions in KD. We examined histological sections of the coronary arteries from five patients with KD who underwent coronary bypass grafting procedure as treatment for giant aneurysms and subsequent stenosis. Immunohistochemical expression of M1- and M2-macrophage markers was assessed to determine the macrophage phenotype of KD to compare with that of atherosclerosis in eight adult patients. All the KD specimens showed a mild to moderate degree of intimal thickening consisting of mature fibrous tissue and distortion of elastic fibers, mimicking the histological features of atherosclerosis. The total number of CD68 positive macrophages was higher in atherosclerosis than in KD specimens. Among the CD68 positive macrophages, the proportion of M1 phenotype, detected by CD86 or SOCS3, was higher in KD than in atherosclerosis. In contrast, the proportion of M2 phenotype, detected by CD163 or MRC1, was higher in patients with atherosclerosis. Despite similar histological features, KD and atherosclerosis appear to have a different immunological etiology for progression of the chronic vascular lesions. A further study enrolling a larger number of cases is required to delineate underlying mechanisms of vascular complications in KD.