Comparison of circulating dendritic cell and monocyte subsets at different stages of atherosclerosis: insights from optical coherence tomography

Background: While specific patterns of circulating dendritic cells (DCs) and monocytes are associated with the incidence of coronary artery disease, the characterization of circulating DC and monocyte subsets in patients with different stages of atherosclerosis remains unclear. Methods: Forty-eight patients with unstable angina pectoris (UAP) diagnosed by angiography were enrolled. Likewise, 31 patients with ST-segment elevation myocardial infarction (STEMI) were enrolled and confirmed with the presence of thrombosis by angiography. Plaque features of 48 UAP patients were evaluated at the culprit lesions by OCT. Circulating myeloid DCs (mDCs), plasmacytoid DCs (pDCs) and monocyte subsets were analyzed using flow cytometry. Results: The proportions and absolute counts of mDC2s, which specifically express CD141 and possess the ability to activate CD8+ T lymphocytes, significantly decreased in patients with UAP and STEMI when compared with controls (0.08 x 10(4) +/- 0.05 x 104/ml and 0.08 x 10(4) +/- 0.06 x 10(4)/ml vs. 0.11 x 10(4) +/- 0.06 x 10(4)/ml, p = 0.027). On the other hand, patients with UAP and STEMI had significantly higher proportions and counts of Mon2 subsets. In the OCT subgroup, patients with thin-cap fibroatheroma (TCFA) had higher proportions and absolute number of Mon2 (11.96% (+/-)4.27% vs. 9.42% (+/-)4.05%, p = 0.034; 5.17 x 10(4)/ml +/- 1.92 x 10(4)/ml vs. 3.53 x 10(4)/ml +/- 2.65 x 10(4)/ml, p = 0.045) than those without TCFA. However, there was no remarkable difference in mDC2s between patients with and without TCFA. Conclusions: Circulating Mon2 appears to be a promising marker for the severity of atherosclerotic plaque.