Introduction: Monocytes and leucocytes (WBC) play a key role in acute coronary syndromes (ACS). We hypothesized that gene expression profiling of WBC from the site of coronary occlusion in direct comparison with peripheral WBC from patients with ACS might reveal genetic patterns involved in plaque rupture.
Methods: Thrombi (Thr) were aspirated during primary percutaneous coronary intervention (PCI), snap-frozen, and stored at −80°C. Peripheral blood leukocytes (PBL) from the same patients were extracted and treated accordingly. Total RNA was isolated from thrombi and PBL. The quality and quantity of the isolated RNA was determined using bioanalyzer and nanodrop devices. The cDNA was prepared using a primer mix and reverse transcriptase, followed by fragmentation and biotinilation. Biotin-labeled single-stranded cDNA samples were hybridized to Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays. An Affymetrix GeneChip Scanner was used to measure the fluorescent intensity emitted by the labelled target.
Results: Gene expression profiles of Thr and PBL from 4 patients during PCI were assessed by Affymetrix human genome U133 Plus 2.0 arrays (54′675 probe sets). 653 different genes were locally upregulated in Thr compared to PBL as defined by a more than 8-fold difference in expression and statistical significance (p≤0.01). Genes for proteins of inflammation, thrombosis, endothelial activation, extracellular matrix remodelling, and scavenger receptors were highly upregulated at the site of coronary occlusion (examples see table 1
).
Conclusion: The local gene expression profile in WBC from thrombi differs significantly from the pattern in PBL, reflecting the regulatory and effective role of these cells in plaque rupture and thrombosis. This study identifies the upregulation of genes encoding for a host of established and new pathways involved in inflammation, uptake of oxidized LDL, and coagulation, that might play a crucial role in ACS.
Table 1
Coverage and Characteristics of the Affymetrix GeneChip Human Mapping 100K SNP Set