Differences in Gene Expression and Gene Associations in Epicardial Fat Compared to Subcutaneous Fat

Epicardial adipose tissue (EAT) plays a role in cardiac physiology and may contribute to the development of coronary artery disease. Our objective was to determine whether there was a significant difference in gene expression in EAT compared to subcutaneous adipose tissue (SAT) and to identify potential relationships. MEDLINE and EMBASE were searched using the key terms “Epicardial Adipose Tissue” or “Epicardial Fat” in combination with “RNA”, “mRNA”, or “gene”. The entry criteria were studies that presented primary data including expression levels of mRNA in human EAT compared with SAT and an expression of variance (SD). Genes identified by 2 or more studies were evaluated. Genes that showed significant change in expression between EAT and SAT were examined using the Gene Functional Classification analytical tool in Database for Annotation, Visualization and Integrated Discovery and cross-validated by ToppGene. Seventeen genes were identified from 25 studies. Meta-analysis showed that 10 genes (ADORA1, adiponectin, AGT, ADM, CATA, IL-1β, MCP-1, RBP-4, TNF-α, UCP-1) were significantly different in EAT. Gene Functional Classification analysis yielded 23 clusters with significant relationships. The top clusters were focused on responses to glucocorticoid stimulus, regulation of apoptosis, cellular ion homeostasis, and responses to hormone stimulus. Genetic analysis shows that EAT is discretely different from SAT. ADORA1, adiponectin, AGT, ADM, CATA, IL-1β, MCP-1, RBP-4, TNF-α, and UCP-1 may play significant roles in the unique physiology of EAT and/or its role in pathophysiology, through mechanisms as diverse as steroid hormone responses and regulation of apoptosis.