EPICARDIAL ADIPOSE TISSUE, OBESITY AND INFLAMMATION IN ATHEROSCLEROSIS

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DESCRIPTION (provided by applicant): Epicardial adipose tissue (EAT) is present in close proximity to the adventitia of the coronary arteries and the underlying myocardium, and functions as both endocrine organ and inflammatory tissue, secreting hormones, cytokines and chemokines. Since atherosclerotic lesions result from inflammation and extracellular matrix formation that are exaggerated by obesity, there is a poor outcome in obese atherosclerotic patients following contrary intervention. We hypothesize that obesity-induced inflammatory phenotype of epicardial fat is exacerbated by vitamin D deficiency leading to endothelial dysfunction and enhanced intimal hyperplasia following coronary intervention. Aim 1: Our hypothesis predicts that high fructose and high fat diet will increase thickness and the inflammatory phenotype of EAT accompanied with impairment of coronary vasodilatation and increased reoccurrence of cardiovascular events following coronary artery intervention. Aim 2: Our hypothesis predicts that vitamin D deficiency will exacerbate and vitamin D supplementation will decrease thickness and the inflammatory phenotype of EAT and restore coronary vasodilatation and this will correlate with decreased reoccurrence of cardiovascular events following coronary artery intervention. Aim 3: Our hypothesis predicts that enhanced inflammatory phenotype of EAT in obese and atherosclerotic swine is due to increased translocation of NF-κB to the nucleus via increased transcription and translation of importin-α3 and decreased prohibitin and SOCS3, and vitamin D suppresses pro-inflammatory responses in EAT. Hypercholesterolemic swine on high fructose diet will undergo balloon angioplasty and stenting. Effect of vitamin D will be examined in vitamin D-deficient, -sufficient and supplemented swine fed with high cholesterol and high fructose diet. Epicardial fat thickness will be measured by cardiac CT. Angiogram and Optical Coherence Tomography will be done to assess cardiac function and quantify in-segment minimal luminal diameter and intimal hyperplasia. Endothelium-dependent and -independent coronary vasodilatation will be measured by intracoronary administration of adenosine and acetylcholine. Biochemical parameters in epicardial fat will include the changes in adipocyte size, M1/M2 macrophage polarity, T-lymphocyte subsets, levels of pro- and anti-inflammatory mediators and cytokines. Histologically, intimal thickness and intimal hyperplasia, lumen area, intima-media ratio, plaque development, and re-occlusion will be examined. The proposed studies will provide conceptual support of our hypothesis and position us to translate our investigation into a clinical study in obese patients with coronary artery disease.