Abstract 1726: Genome-Wide Cell-Specific Gene Expression Analysis Identifies the Involvement of the Adipocytokine Signalling Pathway in Atherosclerotic Plaque Rupture
The molecular mechanisms leading to plaque rupture are poorly understood. Genome-wide gene expression studies may reveal novel causal molecular pathways.
METHODS: Snap-frozen human atherosclerotic plaques removed at carotid endarterectomy were designated as stable or ruptured using stringent clinical, radiological and histopathological criteria. Accurate gene expression profiling of macrophages in 5 ruptured and 6 stable plaques was conducted by employing Laser Micro-Dissection to specifically isolate this cell type from the plaques. High quality RNA was amplified and hybridised to the genome-wide Affymetrix U133plus2 microarray.
RESULTS: Exploratory clustering by Principal Components Analysis showed the data to cluster into 2 distinct groups- stable and ruptured. We identified 889 statistically significant differentially expressed genes between the two groups (Fig.1⇓). Genes involved in lipid processing, signalling, apoptosis, immune response and extracellular matrix were found to play a role in plaque rupture. Pathway analysis identified the Adipocytokine Signalling Pathway to be the most significantly represented cell signalling pathway (p<0.0006). The microarray findings were technically validated by real-time qPCR (Pearson Correlation R=0.94) and biologically cross-validated on a larger number of samples successfully (n=25). Immunocytochemical staining confirmed the differential Leptin expression in macrophages of ruptured and stable plaques.
CONCLUSION: The involvement of Leptin and the Adipocytokine Signalling Pathway in macrophages in plaque rupture has been implicated here for the first time and may be a potential therapeutic target.