Association of Toll-Like Receptor 4 on Human Monocyte Subsets and Vulnerability Characteristics of Coronary Plaque as Assessed by 64-Slice Multidetector Computed Tomography.

BACKGROUND

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).

METHODS AND RESULTS

We enrolled 65 patients with SAP who underwent MDCT. Three monocyte subsets (CD14CD16, CD14CD16, and CD14CD16) 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 CD14CD16monocytes more frequently expressed TLR-4 than CD14CD16and CD14CD16monocytes (P<0.001). The relative proportion of the expression of TLR-4 on CD14CD16monocytes 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 CD14CD16monocytes 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).

CONCLUSIONS

Upregulation of TLR-4 on CD14CD16monocytes might be associated with coronary plaque vulnerability in patients with SAP.