Low levels of Nogo-B in human carotid atherosclerotic plaques are associated with an atheromatous phenotype, restenosis, and stenosis severity

Abstract

OBJECTIVE - Reticulon-4/Nogo (Nogo-B) protects mouse arteries from lumen loss by reducing smooth muscle cell (SMC) migration and intimal thickening. Our goal was to determine plaque and circulating levels of Nogo-B in atherosclerotic and control subjects. Therefore, we studied the relationships between local Nogo-B, plaque characteristics, and clinical data in patients undergoing carotid endarterectomy. METHODS AND RESULTS - Western blot analysis showed that endarterectomy specimens from the femoral (n=19) and carotid arteries (n=145) contained significantly less Nogo-B than nonatherosclerotic mammary arteries (n=8; P<0.003) and aortas (n=15; P=0.03). Immunohistochemistry revealed that in atherosclerotic lesions, Nogo-B was expressed by macrophage/foam cells, SMC rich, and neo-vascularized areas. Atheromatous plaques (>40% fat content) showed a significant reduction in Nogo-B expression (P=0.002). Nogo-B expression levels were significantly lower in patients with more than 90% of carotid stenosis (P=0.04) or restenotic lesions after prior carotid intervention (duplex; P=0.01). In contrast, plasmatic levels of Nogo-B (soluble Nogo-B) did not differ between atherosclerotic subjects (n=68) and risk-factor matched controls (n=63; P=0.5). CONCLUSION - Our findings suggest that local reduction of Nogo-B in atherosclerotic tissue might contribute to plaque formation and/or instability triggering luminal narrowing. In contrast, plasma Nogo-B levels are not associated with clinically manifested atherosclerotic disease. © 2007 American Heart Association, Inc.