Role of Epicardial Adipose Tissue in Health and Disease: A Matter of Fat? (original) (raw)

2017, Comprehensive Physiology

Running head Role of epicardial fat in health and disease Didactic synopsis Major teaching points:" followed by a bulleted list of 5-10 summary statements.  EAT is an ectopic fat depot located between myocardium and the visceral pericardium with no fascia separating the tissues, allowing local interaction and cellular cross-talk between myocytes and adipocytes  Given the lack of standard terminology, it is necessary to make a distinction between epicardial and pericardial fat to avoid confusion in the use of terms. The pericardial fat refers to the combination of epicardial fat and paracardial fat (located on the external surface of the parietal pericardium)  Imaging techniques such as echocardiography, computed tomography or magnetic resonance imaging are necessary to study EAT distribution in humans  Very little amount of EAT is found in rodents compared to humans  EAT displays high rate of fatty acids metabolism (lipogenesis and lipolysis), thermogenic (beiging features), and mechanical properties (protective framework for cardiac autonomic nerves and vessels)  Compared to visceral fat, EAT is likely to have predominant local effects  EAT secretes numerous bioactive factors including adipokines, fibrokines, growth factors and cytokines that could either be protective or harmful depending on the local microenvironement  Human EAT has a unique transcriptome enriched in genes implicated in extracellular matrix remodeling, inflammation, immune signaling, beiging, thrombosis and apoptosis pathways  Epicardial adipocytes have a mesothelial origin and derive mainly from epicardium. Cells originating from the Wt1+ mesothelial lineage, can differentiate into EAT and this "epicardium-to-fat transition" fate could be reactivated after myocardial infarction  Factors leading to cardiac ectopic fat deposition may include dysfunctional subcutaneous adipose tissue, fibrosis, inflammation, hypoxia, and aging  Periatrial EAT has a specific transcriptomic signature and its amount is associated with atrial fibrillation  EAT is likely to play a role in the pathogenesis of cardiovascular disease and coronary artery disease  EAT amount is a strong independent predictor of future coronary events  EAT is increased in obesity, type 2 diabetes, hypertension, metabolic syndrome, nonalcoholic fatty liver disease, and obstructive sleep apnea (OSA)