Ph.D Thesis

Ph.D StudentNahum Sagi
SubjectGene Expression in Peripheral Blood Cells of Patients with
Multi-Vessel Coronary Artery Disease and Acute
Myocardial Infarction
DepartmentDepartment of Medicine
Supervisors PROF. Doron Aronson
PROF. Eli Sprecher
Full Thesis textFull thesis text - English Version


Introduction: Atherosclerotic plaque rupture leading to intraluminal thrombosis is the most common cause of acute myocardial infarction (MI). The fact that patients with severe multivessel coronary artery disease (MV-CAD) remain stable for years without developing acute coronary events, while others develop MI despite mild coronary atherosclerosis suggests that mechanisms that predispose to atherosclerotic plaque growth may differ from those predisposing to plaque rupture and acute MIWe hypothesized that stable MV-CAD and MI phenotypes may be associated with divergent gene expression profiles in peripheral blood mononuclear cells (PBMCs).

Methods: Whole genome microarray analysis (Illumina) was performed using RNA extracted from PBMCs of 3 groups of patients: 1) patients with severe multivessel MV-CAD (n=9); 2) patients with ST-elevation MI (n=14) but mild atherosclerosis; 3) subjects with normal coronary arteries (NC) (n=11). Microarray data was analysed for differentially expressed genes between groups.

Results: Comparative analysis revealed 782 genes that were differentially expressed between groups (P < 0.05, FDR<0.25). Among these, 298 genes were differentially expressed using a cut-off of ±1.3 fold change. The comparison with the largest number of unique differentially expressed genes was MV-CAD vs. NC, (n=161), followed by MV-CAD vs. MI (n=159), and MI vs. NC (n=96). Differentially expressed genes encoded proteins known to play an important role in the pathogenesis of atherosclerosis such as COX-2, EGR?-1, JUNB, IL-1b, OSM, NAMPT, SOD2, TLR4 and TLR6 and in atherosclerosis-associated apoptosis (TNFSF10, TNFRSF10B, TNFRSF8 and CEBPB). There was a significant positive correlation between median expression of the inflammatory genes and the angiographic Gensini score for the quantitation of atherosclerosis severity (r=0.47, P = 0.006). Pathway analysis identified a graded enrichment in inflammation-related canonical pathways that are linked to atherosclerosis, with the lowest enrichment in the MI vs. NC comparison (mild atherosclerosis vs. no atherosclerosis), followed by the MV-CAD vs. MI comparison (severe atherosclerosis vs. mild atherosclerosis), with the highest enrichment in the MV-CAD vs NC comparison (severe atherosclerosis vs. no atherosclerosis).  An upstream regulator analysis using differentially expressed genes revealed activation of transcription factors known to be involved in the pathogenesis of atherosclerosis, including the nuclear factor-kB (NFkB),

 Conclusion: The results of the present study demonstrate that PBMCs expression profile of patients with CAD is characterized by differential expression of specific genes and molecular networks that bear functional relevance to the atherogenic processes occurring in the vessel wall. Inflammatory gene expression in PBMCs mainly reflects the severity of atheromatous burden.