Association of Toll-Like Receptor 4 on Human Monocyte Subsets and Vulnerability Characteristics of Coronary Plaque as...

Although Toll-like receptor 4 (TLR-4) is involved in monocyte activation in patients with accelerated forms of atherosclerosis, the relationship between the expression of TLR-4 on circulating monocytes and coronary plaque vulnerability has not previously been evaluated. We investigated this relationship using 64-slice multidetector computed tomography (MDCT) in patients with stable angina pectoris (SAP).

We enrolled 65 patients with SAP who underwent MDCT. Three monocyte subsets (CD14⁺⁺CD16^-, CD14⁺⁺CD16⁺, and CD14⁺CD16⁺) and expression of TLR-4 were measured by flow cytometry. Intracoronary plaques were assessed by 64-slice MDCT. We defined vulnerability of intracoronary plaques according to the presence of positive remodeling (remodeling index >1.05) and/or low CT attenuation (<35 HU). The circulating CD14⁺⁺CD16⁺monocytes more frequently expressed TLR-4 than CD14⁺⁺CD16^-and CD14⁺CD16⁺monocytes (P<0.001). The relative proportion of the expression of TLR-4 on CD14⁺⁺CD16⁺monocytes was significantly greater in patients with vulnerable plaque compared with those without (10.4 [4.1-14.5] % vs. 4.5 [2.8-7.8] %, P=0.012). In addition, the relative proportion of TLR-4 expression on CD14⁺⁺CD16⁺monocytes positively correlated with the remodeling index (r=0.28, P=0.025) and negatively correlated with CT attenuation value (r=-0.31, P=0.013).

Upregulation of TLR-4 on CD14⁺⁺CD16⁺monocytes might be associated with coronary plaque vulnerability in patients with SAP.