Perivascular Adipose Tissue Inflammation and Coronary Artery Disease: An Autopsy Study Protocol

Abstract

BackgroundPerivascular adipose tissue (PAT) inflammation may have a role in coronary artery disease (CAD) pathophysiology. However, most evidence has come from samples obtained during surgical procedures that may imply in some limitations. Moreover, the role of B lymphocytes and inflammation in PAT that is adjacent to unstable atheroma plaques has not been investigated in humans using morphometric measurements.ObjectiveThe objective of this study is to investigate the inflammation in PAT, subcutaneous, and perirenal adipose tissues (SAT and PrAT) among chronic CAD, acute CAD, and control groups in an autopsy study.MethodsHeart, SAT, and PrAT samples are collected from autopsied subjects in a general autopsy service, with the written informed consent of the next-of-kin (NOK). Sociodemographic and clinical data are obtained from a semistructure interview with the NOK. Coronary arteries are dissected and PAT are removed. Sections with the greatest arterial obstruction or unstable plaques, and the local with absence of atherosclerosis in all coronary arteries are sampled. PAT are represented adjacent to these fragments. Adipose tissues are fixed in 4% buffered paraformaldehyde solution and analyzed immunohistochemically for macrophages (CD68), macrophage polarization (CD11c for proinflammatory and CD206 for anti-inflammatory), B lymphocytes (CD20), and T lymphocytes (CD3). Slides will be scanned, and inflammatory cells will be quantified in 20 random fields. Participants will be categorized in CAD groups, after morphometric measurement of arterial obstruction and plaque composition analysis in accordance with American Heart Association classification. Three study groups will be investigated: acute CAD (at least one unstable plaque); chronic CAD (≥50% arterial obstruction); and controls (<50% arterial obstruction). Inflammatory cells in PAT, SAT, and PrAT will be counted and compared between groups using multivariate linear regression, adjusted for age, body mass index, hypertension, diabetes, alcohol use, and smoking.ResultsWe present the methods of our study that was developed from 2 pilots. Currently, data collection and tissue processing are ongoing. Data collection, histology and immunochemistry procedures, and quantification of all inflammatory cells are expected to be concluded within 1 year.ConclusionsThis study will contribute for the understanding of the mechanisms of CAD pathophysiology because it will help to clarify the role of inflammation both in chronic and acute CAD.

Overexpression of scavenger receptor and infiltration of macrophage in epicardial adipose tissue of patients with ischemic heart disease and diabetes

“…Also, this is not a study entirely new. Earlier reports have already described recruitment of macrophages to EAT [18, 19], with an increase in T2DM patients [43]. Moreover, we recruited a relatively small number of patients; our data were from a single hospital and only small samples of EAT were collected from each patient, being insufficient for a thorough analysis and correlation between mRNA expression and protein.…”

“…The inflammation of EAT has been linked to IHD pathophysiology, which can be reflected by increased of macrophage infiltration [ 16 , 17 ]. In this state, EAT shows a high infiltration of leukocytes [ 18 ], specifically T lymphocytes and macrophages [ 18 , 19 ] and inflammatory cytokines [ 20 ].…”

Macrophage Polarization in the Perivascular Fat Was Associated With Coronary Atherosclerosis

“…Exclusion criteria were NOK unable to answer the questions of the semistructured interview, fixation of PvAT >72 hours prior, heart with signs of autolysis, heart disease attributable to local inflammation (eg hemopericardium, presence of a stent), previous cardiac surgery, immunosuppression by drugs/radiotherapy, autoimmune diseases, a site with a myocardial bridge, and the presence of sepsis or systemic inflammation detected through biopsy of main organs. 16 …”

Inflammatory cells in perivascular adipose tissue and the integrity of the tunica media in atherosclerotic coronary arteries

“…Now, it has become evident that PVAT has a crucial role in maintaining the normal function of CAs [4][5][6], and that it is also involved in the development of CAD [7,8] and hypertension [9]. It has been shown that both vascular smooth muscle and PVAT release a variety of vasoactive factors as well as pro and antiinflammatory cytokines that modulate vascular function and structure [8,[10][11][12][13][14]. Increasing evidence supports the view that inflammatory cytokines released by PVAT may substantially contribute to CAD.…”