Abstract 5167: Neutrophil Infiltration of Human Carotid Plaques Correlates With the Characteristics of Rupture-prone Lesions

Abstract

Aim : Atherosclerosis is a chronic, complex inflammatory process and is the underlying cause of stroke and myocardial infarction due to rupture of the atherosclerotic plaque leading to acute occlusion of the artery in the brain or heart. Little is known about neutrophil infiltration in human carotid atherosclerotic plaques and its association with plaque morhology has not been described yet. This, despite accumulating evidence suggesting a link between systemic inflammation and atherosclerosis. To study this, we scored the number of plaque neutrophils and related this to plaque morphology and inflammatory status. Methods and Results : Carotid atherectomy specimens were obtained from 340 patients and stained for the neutrophil marker CD66b. CD66b-positive neutrophils were counted and expressed as number per square millimeter of tissue. Higher neutrophil numbers were found in plaques with a high lipid core, high macrophage numbers and low collagen and smooth muscle cell numbers. Plaques with high neutrophil numbers contained significant higher interleukin-8 (p=0.001), matrix metalloprotease (MMP)-8 (p=0.039) and MMP-9 (p=0.002) concentrations. The number of new capillaries within plaques was significantly (p=0.045) correlated with high neutrophil numbers. Conclusion : This shows for the first time that Neutrophil-numbers are strongly associated with the histopathological features and the inflammatory status of rupture-prone atherosclerotic lesions, suggesting a possible role for neutrophils in plaque destabilization.