Carotid plaque mast cells associate with atherogenic serum lipids, high grade carotid stenosis and symptomatic carotid artery disease. Results from the helsinki carotid endarterectomy study

OBJECTIVE: Increased numbers of mast cells (MCs) are present in ruptured coronary plaques, suggesting to play a role in acute coronary syndromes. We evaluated the distribution densities of MCs, macrophages and T cells in carotid plaques and correlated these findings to stroke risk factors as well as history of stroke or TIA. METHODS AND RESULTS: Seventy-eight carotid samples from 75 patients (16 plaques from asymptomatic patients and 62 from patients with recent ischemic symptoms) undergoing carotid endarterectomy with an internal carotid stenosis >70% that were immunostained and quantified for MCs, macrophages and T cells. The MC distribution density showed positive correlation with the degree of carotid stenosis (p = 0.012), serum levels of total cholesterol (p = 0.021), LDL cholesterol (p = 0.013) and triglycerides (p = 0.005), and an inverse correlation with serum HDL cholesterol levels (p = 0.001). The average MC density (p = 0.023), but not the macrophage (p = 0.58) or T cell (p = 0.74) density, was higher in the symptomatic than in the asymptomatic patients. In a comparison of plaques ipsilateral and contralateral to the thromboembolic event, the densities of the three types of inflammatory cells were similar. CONCLUSIONS: Increased MC distribution density is associated with an atherogenic serum lipid profile, high-grade carotid artery stenosis and symptomatic carotid artery disease. These findings suggest a potential involvement of MCs in the pathophysiology of carotid artery stenosis.