OBJECTIVE: Although monocytes appear to be actively involved in the onset of acute coronary syndrome (ACS), they are heterogenous in human peripheral blood. How up-regulation of monocyte subsets leads to coronary plaque rupture followed by thrombus formation remains unclear. Recent studies have shown that P-selectin glycoprotein ligand-1 (PSGL-1) is involved in monocyte activation in patients with thrombus formation. We therefore investigated the relationship between the expression of PSGL-1 on monocyte subsets and thrombus formation using frequency-domain optical coherence tomography (FD-OCT) in patients with ACS. METHODS: We enrolled a total of 100 individuals in this study: patients with acute myocardial infarction (AMI, n=25), unstable angina pectoris (UAP, n=20), or stable angina pectoris (n=35) who underwent coronary angiography, and control subjects (n=20). Three monocyte subsets (CD14++CD16-, CD14++CD16+, and CD14+CD16+) and the expression of PSGL-1 were measured by flow cytometry. In patients with AMI and UAP, FD-OCT was performed before percutaneous coronary intervention. RESULTS: Circulating peripheral CD14++CD16+ monocytes expressed PSGL-1 more frequently than CD14++CD16- and CD14+CD16+ monocytes in patients with ACS. The expression of PSGL-1 on circulating peripheral CD14++CD16+ monocytes was significantly elevated in patients with AMI compared with the other 3 groups. Moreover, the expression levels of PSGL-1 on CD14++CD16+ monocytes were significantly higher in patients with plaque rupture or intracoronary thrombus assessed by FD-OCT. CONCLUSION: Up-regulation of PSGL-1 on CD14++CD16+ monocytes may be a crucial role in plaque rupture and thrombus formation.
OBJECTIVE: Although monocytes appear to be actively involved in the onset of acute coronary syndrome (ACS), they are heterogenous in human peripheral blood. How up-regulation of monocyte subsets leads to coronary plaque rupture followed by thrombus formation remains unclear. Recent studies have shown that P-selectin glycoprotein ligand-1 (PSGL-1) is involved in monocyte activation in patients with thrombus formation. We therefore investigated the relationship between the expression of PSGL-1 on monocyte subsets and thrombus formation using frequency-domain optical coherence tomography (FD-OCT) in patients with ACS. METHODS: We enrolled a total of 100 individuals in this study: patients with acute myocardial infarction (AMI, n=25), unstable angina pectoris (UAP, n=20), or stable angina pectoris (n=35) who underwent coronary angiography, and control subjects (n=20). Three monocyte subsets (CD14++CD16-, CD14++CD16+, and CD14+CD16+) and the expression of PSGL-1 were measured by flow cytometry. In patients with AMI and UAP, FD-OCT was performed before percutaneous coronary intervention. RESULTS: Circulating peripheral CD14++CD16+ monocytes expressed PSGL-1 more frequently than CD14++CD16- and CD14+CD16+ monocytes in patients with ACS. The expression of PSGL-1 on circulating peripheral CD14++CD16+ monocytes was significantly elevated in patients with AMI compared with the other 3 groups. Moreover, the expression levels of PSGL-1 on CD14++CD16+ monocytes were significantly higher in patients with plaque rupture or intracoronary thrombus assessed by FD-OCT. CONCLUSION: Up-regulation of PSGL-1 on CD14++CD16+ monocytes may be a crucial role in plaque rupture and thrombus formation.