Adipocytes Size of the Epicardial Adipose Tissue in Patients With Coronary Artery Disease and Coronary Atherosclerosis: Relationship With Parameters of Blood Lipid Transport Function, Carbohydrate Metabolism and Inflammatory Markers

Aim. To assess the potential relationship between morphometric characteristics of adipocytes in epicardial and subcutaneous adipose tissue (EAT, SAT) and the lipid transport function of the blood, glucose e metabolism, and inflammatory biomarkers in patients with ischemic heart disease (IHD) after coronary artery bypass grafting. Material and methods. The study included 47 patients (33 men and 14 women) aged 53-72 years with chronic IHD. The study material was EAT and SAT adipocytes obtained from intraoperative explants. The size of EAT and SAT adipocytes and the proportion of EAT and SAT adipocytes with ≥100 μm and ≤50 μm sizes were determined. Carbohydrate metabolism parameters, blood lipid transport function, and inflammatory biomarkers were assessed. Surrogate indices of insulin resistance (IR) were calculated. Results. The mean size of EAT adipocytes, in contrast to SAT adipocytes, correlated (p<0.05) with serum concentrations of tumor necrosis factor alpha (TNF-α) (rs=0.43), triglycerides (TG) (rs=0.36), interleukin (IL)-1β (rs=0.29), basal C-peptide (rs=0.40) and TyG index (rs=0.32). Male gender and blood concentrations of basal C-peptide and TG in combination were identified as statistically significant determinants of an increase in the mean size of EAT adipocytes. The threshold values of TG and non-high-density lipoprotein cholesterol (nHDL-C) associated with an increase in the mean size of EAT adipocytes ≥87.61 μm were 1.4 and 2.63 mM, respectively. Patients with TG concentrations ≥1.4 mM had a greater size and proportion of hypertrophied EAT adipocytes, IR indices, and higher blood concentrations of basal glucose, high-sensitivity C-reactive protein, TNF-α, and IL-1β. TG concentrations of 1.2-1.4 mM, compared with concentrations <1.2 mM, were associated with a greater mean size of EAT adipocytes and higher serum IL-10 concentrations. Patients with non-HDL-C ≥2.63 mM, compared with its lower concentrations, had more pronounced hypertrophy of EAT adipocytes. Conclusion. Disorders in the morphometric characteristics of EAT adipocytes, in contrast to SAT adipocytes, are associated with increased blood concentrations of TG, non-HDL-C, inflammatory markers, and increased IR indices. It was shown for the first time that a combination of three factors, male gender, blood concentrations of basal C-peptide, and TG, independently of other indicators describe the variability of the mean size of EAT adipocytes. Increases in TG from 1.2 to 1.4 mM are associated with a larger size of EAT adipocytes and cytokine imbalance. Our data confirm the validity of identifying optimal blood concentrations of TG and non-HDL-C in patients with IHD and coronary atherosclerosis.