Abstract 957: Elevated Levels of Neopterin are Associated with Carotid Complex Plaques in Patients with Stable Angina Pectoris
Background: Neopterin is produced by activated macrophages and serves as an activation marker for monocytes/macrophages. Serum levels of neopterin have been shown to be associated with the presence of complex coronary lesions in unstable angina pectoris. However, the relationship between neopterin levels and complex carotid lesions is still unknown. We investigated the association between plasma neopterin levels and the characteristics of carotid plaques in patients with stable angina pectoris (SAP). Moreover, we immunohistochemically studied the presence of neopterin in carotid endarterectomy specimens.
Methods: We studied 65 SAP patients who were scheduled coronary angiography. In all patients, plasma neopterin levels were measured and carotid ultrasound was performed for evaluation of carotid artery plaque score (PS) defined by the sum of plaque thickness, plaque number (PN) and plaque surface irregularity. Frozen tissue of 40 endarterectomy specimens for extracranial high-grade carotid stenosis were immunohistochemically examed with antibodies against macrophages and neopterin.
Results: There was no significant correlation between plasma neopterin levels and PS (P=0.38) or PN (P=0.49). On the other hand, plasma neopterin levels were significantly higher in patients with carotid plaque surface irregularity compared with patients without it (25.4 ± 13.5 nmol/L vs.16.9 ± 6.5 nmol/L, P=0.0015). Carotid plaque irregularity was detected more frequently in patients with higher neopterin levels (>=18.5 nmol/L median) compared with those with lower neopterin levels (41.9% vs. 16.1%, P=0.025). Using multivariate analyses, nepopterin levels (OR, 1.11; 95%CI, 1.01 to 1.21; P=0.023) and the number of diseased coronary vessels (OR, 2.51; 95%CI, 1.01 to 6.22; P=0.047) are independently associated with carotid plaque irregularity. Immunohistochemical staining showed abundant neopterin-positive macrophages in the unstable carotid plaques.
Conclusions: Neopterin levels are associated with carotid complex plaques rather than the severity of carotid atherosclerotic change. Neopterin can be considered as one of the significant markers of plaque destabilization in not only coronary artery but carotid artery atherosclerotic lesions.