Gene expression profiling of human atherosclerotic plaque: 290 peripheral plaques

In order to identify potential new biomarkers of atherosclerotic plaque composition we performed a large scale analysis of gene expression patterns in human atherosclerotic lesions. Whole genome expression analysis of 101 peripheral plaques identified a robust gene signature (1514 genes) dominated by inflammatory processes, and cholesterol metabolism and storage genes. Specific pathways enriched in this signature included activation of the Toll-like receptor signaling pathway, T-cell activation, cholesterol efflux, oxidative stress response, inflammatory cytokine production, vasoconstriction and lysosomal activity. Analysis of gene expression in plaque micro-dissected material revealed that the signature is strongly up-regulated in macrophage-rich regions and down-regulated in regions with high smooth muscle cell content. A smaller qPCR biomarker panel and inflammatory composite score (ICS) were developed to facilitate clinical translation of discoveries from gene expression profiling. We found that ICS correlates with histological features related to plaque vulnerability. In addition, ICS is able to separate groups of plaques obtained from symptomatic and asymptomatic patients undergoing carotid endarerectomy. In summary, we identified a robust mRNA biomarker panel associated with histo-pathological as well as clinical hallmarks of vulnerable atherosclerotic plaque. This panel may be used as a diagnostic and prognostic tool in clinical setting to evaluate novel anti-atherosclerotic therapies. 290 human peripheral plaques were excised using the FoxHollow silverhawk catheter and stored in RNAlater. RNA was extracted, amplified and hybridized to Affymetrix/Merck custom 1.0 arrays (GPL10687).