Research proposal: inflammation and oxidative stress in coronary artery bypass surgery graft: comparison between diabetic and non-diabetic patients

Romano e Silva et al. BMC Res Notes (2018) 11:635 https://doi.org/10.1186/s13104-018-3743-5 BMC Research Notes Open Access RESEARCH NOTE Research proposal: inflammation and oxidative stress in coronary artery bypass surgery graft: comparison between diabetic and non‑diabetic patients Ana Catarina Romano e Silva1, Glauber Monteiro Dias1, Jorge José de Carvalho2, Andrea De Lorenzo1 and Daniel Arthur Barata Kasal1,2* Abstract Background: Diabetes mellitus patients (DM) have more severe progression of atherosclerotic disease than non-diabetic (NDM) individuals. In situ inflammation and oxidative stress are key points in the pathophysiology of atherosclerosis, a concept largely based on animal model research. There are few studies comparing inflammation and oxidative stress parameters in medium-sized arteries between DM and NDM patients. A fragment of the internal mammary artery used in coronary artery bypass grafting (CABG) will be employed for this purpose Objective: To assess the expression of inflammatory markers tumor necrosis factor-α, transforming growth factor-β1, nuclear factor kappa B, the enzymes superoxide dismutase, and catalase in the vascular wall of the arterial graft used in CABG, comparing DM and NDM patients Results: The present study will add information to the vascular degenerative processes occurring in diabetic patients. Keywords: Inflammation, Oxidative stress, Diabetes mellitus, Coronary artery bypass grafting Introduction Coronary artery disease (CAD) is the main cause of death in diabetic patients [1]. Coronary artery bypass grafting (CABG) is one of the most important strategies for CAD treatment [2]. The internal mammary artery (IMA) is the graft of choice for revascularization of the left anterior descending coronary artery [3]. During CABG, not the whole extension of IMA is used by the surgeon. A fragment of the unemployed part of the vessel provides the opportunity to access an artery with similar structure compared to the epicardial coronary arteries [4], as a model for evaluating vascular degenerative processes in these patients. *Correspondence: 1 National Institute of Cardiology, Ministry of Health, Rua das Laranjeiras No. 374, Rio de Janeiro, RJ 22240‑006, Brazil Full list of author information is available at the end of the article Increased inflammation, oxidative stress, and the resulting endothelial dysfunction are key factors to the severity of atherosclerosis in diabetes [5]. While research on the field is largely based on animal models [6–8], only few studies have addressed diabetes-induced molecular mechanisms in human medium-sized arteries [9, 10]. The goal of this study is to identify the contribution of diabetes to the vascular expression of a group of molecules in CAD patients. For this purpose, we will compare IMA samples obtained from diabetic (DM) versus non-diabetic (NDM) patients subjected to CABG. The selected inflammatory markers will be tumor necrosis factor-α (TNF-α), transforming growth factor β-1 (TGFβ-1), and nuclear factor kB (NF-κB). Oxidative stress pathways will be evaluated by the expression of the enzymes superoxide dismutase (SOD) and catalase (CAT). TNF-α induces endothelial expression of cell adhesion molecules, vascular cell adhesion molecule (VCAM) and © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Romano e Silva et al. BMC Res Notes (2018) 11:635 intercellular cell adhesion molecule (ICAM), both important for the infiltration of monocytes at the intima of the vessel [11]. TGFβ-1 is a multifunctional peptide which stimulates cell proliferation, migration, and extracellular matrix deposition, contributing to the vascular remodeling of atherosclerosis [12]. NF-κB is a transcription factor activated both by hyperglycemia and reactive oxygen species (ROS) [13], regulating the expression of cytokines and adhesion proteins, modulating vascular inflammation, and the recruitment of immune cells to the vascular wall [14, 15]. Superoxide dismutase is an essential component of cell defense against ROS, converting superoxide anion to hydrogen peroxide. Catalase is an enzyme with complementary action in ROS elimination, converting hydrogen peroxide to water [16]. An excess of ROS in the vascular tissue is directly related to endothelial dysfunction [17]. Main text Methods Study design and patients This will be a cross-sectional study with convenience sampling. Individuals will be consecutive male adult patients admitted for elective CABG. The surgical strategy will be defined by the National Institute of Cardiology heart team, with none of its members directly involved in the study. Eligibility criteria are male individuals above 18 years old and IMA use in CABG. Exclusion criteria are kidney failure with hemodialysis, known acute or chronic infectious disease, presence of autoimmune disease, or use of immunosuppressants. The study is approved by the Local Ethics Research Committee under protocol # 33705614.2.0000.5272, and informed consent will be obtained. Based on previous studies with vascular tissue obtained from CABG [9, 10], the total estimated number of patients necessary for this study is 50, equally divided in DM and NDM. Study variables Data from the medical records will be obtained: anthropometric data (height, body weight, abdominal circumference, and body mass index), associated diseases, social habits (cigarette and ethanol consumption), family history of cardiovascular disease, medications, presurgical transthoracic echocardiogram (ejection fraction by Teicholz method), coronary angiography (number of stenotic vessels and percent luminal stenosis), and plasma biochemistry (fasting glucose, sodium, potassium, blood urea nitrogen, creatinine, low-density lipoprotein, highdensity lipoprotein, and triglycerides). Page 2 of 5 Vessel collection and processing The evaluation of the selected markers will be performed by quantitative real time-polymerase chain reaction (qPCR) and immunohistochemistry. Initially, the unused fragment of IMA during CABG will be harvested by the surgeon in a glass tube containing 25 ml of cold, sterilized, phosphate buffered saline (PBS). Immediately after collection, the fragment will be delicately flushed and carefully dissected for adventitia removal. It will be divided in two parts. One will be placed in fixative solution paraformaldehyde 4% in PBS. The other portion will be weighed and frozen in liquid nitrogen, for (...truncated)