Epicardial Adipocyte-derived TNF-α Modulates Local Inflammation in Patients with Advanced Coronary Artery Disease

Background: Epicardial Adipose Tissue (EAT) surrounds the epicardium and can mediate harmful effects related to Coronary Artery Disease (CAD). Objective: We explored the regional differences between adipose stores surrounding diseased and non-diseased segments of coronary arteries in patients with advanced CAD. Methods: We enrolled 32 patients with known CAD who underwent coronary artery bypass graft (CABG) surgery. Inflammatory mediators were measured in EAT biopsies collected from a region of the Left Anterior Descending Artery (LAD) with severe stenosis (diseased segment) and without stenosis (non-diseased segment). Results: Mean age was 64.3±11.1 years, and mean EAT thickness was 7.4±1.9 mm. Dyslipidemia was the most prevalent comorbidity (81% of the patients). Out of a total of 11 cytokines, resistin (p=0.039), matrix metallopeptidase 9 (MMP-9) (p=0.020), C-C motif chemokine ligand 5 (CCL-5) (p=0.021), and follistatin (p=0.038) were significantly increased in the diseased compared with the non-diseased EAT segments. Indexed tumor necrosis factor-alpha (TNF-α), defined as the diseased to non-diseased cytokine levels ratio, was significantly correlated with increased EAT thickness both in the whole cohort (p=0.043) and in a subpopulation of patients with dyslipidemia (p=0.009). Treatment with lipid-lowering agents significantly decreased indexed TNF-α levels (p=0.015). No significant alterations were observed in the circulating levels of these cytokines with respect to CAD-associated comorbidities. Conclusion: Perivascular EAT is a source of cytokine secretion in distinct areas surrounding the coronary arteries in patients with advanced CAD. Adipocyte-derived TNF-α is a prominent mediator of local inflammation.