ROLE OF INFLAMMATORY RESPONSES IN INITIATION OF ATHEROSCLEROSIS - EFFECTS OF ANTIINFLAMMATORY DRUGS ON CUFF-INDUCED LEUKOCYTE ACCUMULATION AND INTIMAL THICKENING OF RABBIT CAROTID-ARTERY

Immediately after a cuff-sheathing of rabbit carotid artery, a large number of leukocytes adhered to injured endothelium then infiltrated into the media. These inflammatory responses were followed by an atherosclerotic change, intimal thickening, of the artery. A simultaneous injection of dexamethasone (10 mg/kg i.m.) inhibited the leukocyte accumulation by 74% when evaluated 18 h thereafter. Similarly, 39% inhibition was obtained with the same dose of FR110302, a potent 5-lipoxygenase inhibitor. On the other hand, the same dose of indomethacin, a cyclooxygenase inhibitor, had little effect on the leukocyte accumulation. The intimal thickening which was evaluated 3 weeks after the cuff-treatment was attenuated by a daily dose (10 mg/kg i.m.) of dexamethasone or FR110302 but not by one of indomethacin. The inhibition by the two former drugs were 91 and 58%, respectively. In vitro, the three drugs in concentrations up to 10-mu-M hardly affected endothelial adhesion of PMN which was induced by LPS or IL-1. Though 10-mu-M of FR110302 and indomethacin significantly decreased PMN chemotaxis induced by LTB4, the decreases were less than that at 10-mu-M dexamethasone. These results confirm a possible linkage between inflammation and atherosclerosis, and suggest that 5-lipoxygenase products contribute to the initiation and development of atherosclerosis.