High Levels of Myeloid-related Protein 14 in Human Atherosclerotic Plaques Correlate with the Characteristics of Rupture-prone Lesions

Objective: Atherosclerotic plaque rupture can lead to severe complications such as myocardial infarction and stroke. Myeloid related protein (Mrp)-14, Mrp-8, and Mrp-8/14 complex are inflammatory markers associated with myocardial infarction. It is, however, unknown whether Mrps are associated with a rupture-prone plaque phenotype. In this study, we determined the association between Mrp-14, -8, -8/14 plaque levels and plaque characteristics.

Methods And Results: In 186 human carotid plaques, levels of Mrp-14, -8, and -8/14 were quantified using ELISA. High levels of Mrp-14 were found in lesions with a large lipid core, high macrophage staining, and low smooth muscle cell and collagen amount. Plaques with high levels of Mrp-14 contained high interleukin (IL)-6, IL-8, matrix metalloprotease (MMP)-8, MMP-9, and low MMP-2 concentrations. Mrp-8 and Mrp-8/14 showed a similar trend. Within plaques, a subset of nonfoam macrophages expressed Mrp-8 and Mrp-14 and the percentage of Mrp-positive macrophages was higher in rupture-prone lesions compared to stable ones. In vitro, this subset of macrophages does not acquire a foamy phenotype when fed oxLDL.

Conclusions: Mrp-14 is strongly associated with the histopathologic features and the inflammatory status of rupture-prone atherosclerotic lesions, identifying Mrp-14 as a local marker for these plaques.