Overexpression of eotaxin and the CCR3 receptor in human atherosclerosis -Using genomic technology to identify a potential novel pathway of vascularinflammation

Background-Unstable atherosclerotic lesions typically have an abundant infl ammatory cell infiltrate, including activated T cells, macrophages, and mas t cells, which may decrease plaque stability. The pathophysiology of inflam matory cell recruitment and activation in the human atheroma is incompletel y described. Methods and Results-We hypothesized that differential gene expression with DNA microarray technology would identify new genes that may participate in vascular inflammation. RNA isolated from cultured human aortic smooth muscl e cells treated with tumor necrosis factor-alpha (TNF-alpha) was examined w ith a DNA microarray with 8600 genes, This experiment and subsequent Northe rn analyses demonstrated marked increases in steady-state eotaxin mRNA (>20 fold), a chemokine initially described as a chemotactic factor for eosinop hils. Because eosinophils are rarely present in human atherosclerosis, we t hen studied tissue samples from 7 normal and 14 atherosclerotic arteries. I mmunohistochemical analysis demonstrated overexpression of eotaxin protein and its receptor, CCR3, in the human atheroma, with negligible expression i n normal vessels. Eotaxin was predominantly located in smooth muscle cells. The CCR3 receptor was localized primarily to macrophage-rich regions as de fined by immunopositivity for CD 68; a minority of mast cells also demonstr ated immunopositivity for the CCR3 receptor. Conclusions-Eotaxin and its receptor, CCR3, are overexpressed in human athe rosclerosis, suggesting that eotaxin participates in vascular inflammation. These data demonstrate how genomic differential expression technology can identify novel genes that may participate in the stability of atherosclerot ic lesions.