Monocytes and neutrophils expressing myeloperoxidase occur in fibrous caps and thrombi in unstable coronary plaques

Lack of association between plasma myeloperoxidase levels and angiographic severity of coronary artery disease in patients with acute coronary syndrome

OBJECTIVE

To evaluate the association between plasma myeloperoxidase (MPO) levels and angiographic severity of coronary atherosclerotic lesions in patients with non-ST elevation acute coronary syndrome (ACS).

DESIGN AND METHODS

This cross-sectional study examined high-risk ACS patients who underwent coronary angiography within 72 h of the onset of symptoms by measuring their plasma MPO levels after sheath insertion. Gensini score was used to evaluate angiographic severity of coronary artery disease.

RESULTS

A total of 48 patients were included in the study. Median MPO levels and Gensini scores were 6.9 ng/mL (4.4-73.5 ng/mL) and 10 (0-87.5), respectively. Spearman's correlation coefficient did not show a significant association between MPO levels and Gensini scores (r (s) = 0.2; p = 0.177). There was no correlation between MPO and age, hypertension, diabetes, leukocyte count, troponin I, CK-MB ≥ 2 × ULN (upper limit of normal), TIMI risk score ≥ 4 and Gensini score in the multivariate analysis.

CONCLUSION

Our findings indicate that MPO expression is not associated with anatomical severity of coronary lesions in ACS.

The role of monocytes in atherosclerotic coronary artery disease

Inflammation plays a key role in the pathogenesis of atherosclerosis. The more we discover about the molecular pathways involved in atherosclerosis, the more we perceive the importance of monocytes in this process. Circulating monocytes are components of innate immunity, and many pro-inflammatory cytokines and adhesion molecules facilitate their adhesion and migration to the vascular endothelial wall. In addition to the accumulation of lipids and formation of atherogenic 'foam' cells, monocytes may promote atherosclerotic plaque growth by production of inflammatory cytokines, matrix metalloproteinases, and reactive oxidative species. However, the contribution of monocytes to atherogenesis is not only limited to tissue destruction. Monocyte subsets are also involved in intraplaque angiogenesis and tissue reparative processes. The aim of this overview is to discuss the mechanisms of monocyte activation, the pivotal role and importance of activated monocytes in atherosclerotic coronary artery disease, their implication in the development of acute coronary events, and their potential in cardiovascular reparative processes such angiogenesis.