FoxP3+ T-regulatory lymphocytes in adipose tissue of cardiac surgery patients with different severity of coronary atherosclerosis

Introduction. T-regulatory (T-reg) lymphocytes as the main modulators of immunity, present in ectopic adipose tissue focuses, may be involved in the pathogenesis of atherosclerosis. Currently there is a lack of data regarding T-reg lymphocyte counts, particularly in epicardial (EAT) and thymic adipose tissue (TAT) in patients with coronary atherosclerosis.

Aim: To study the contents of FoxP3+ T-regulatory lymphocytes of peripheral blood, epicardial and thymic adipose tissue in patients with coronary atherosclerosis.

Materials and Methods. The study included a total of 26 cardiosurgical profile patients with coronary atherosclerosis. Patients were divided into two groups via Gensini Score (GS): first group with severe coronary atherosclerosis (GS > 26.5; n = 15) and second group without severe coronary atherosclerosis (GS ≤ 26.5; n = 11). In all patients, the levels of FoxP3 nuclear translocation and the relative content of CD4+CD25^hiFoxP3 and CD4+CD25^loFoxP3 T-reg lymphocytes in peripheral blood, epicardial, thymic, and subcutaneous adipose tissue (SAT) were determined by flow cytometry with imaging.

Results. The group of patients with severe coronary atherosclerosis was characterised by a statistically significant higher median of relative content of CD4+CD25^hiFoxP3 T-lymphocytes (12.0 (6.5; 17.4) vs. 6.82 (3.32; 12.4) %; p = 0.031) and statistically significant lower median of nuclear translocation level of FoxP3 in CD4+CD25^hiFoxP3 T-lymphocytes in TAT (30.82 (18.50; 40.80) vs. 51.91 (25.9; 71.00) %; p = 0.048). Statistically significant correlations between FoxP3 T-reg lymphocyte parameters in different adipose depots and lipid spectrum markers (TC, HDL-C) were found. There were inverse correlations found between EAT and TAT, in particular, between the relative contents of T-reg lymphocytes and of the FoxP3 nuclear translocation level.

Conclusion. Patients with severe coronary atherosclerosis (GS > 26.5 points) were characterised by an increased relative content of CD4+CD25^hiFoxP3 T-lymphocytes in thymic adipose tissue and a decreased level of FoxP3 nuclear translocation in this cell subpopulation compared to patients with moderate atherosclerosis (GS ≤ 26.5 points). Identified correlations between relative content of T-reg lymphocytes and the level of FoxP3 nuclear translocation in thymic and epicardial adipose tissues suggest potential existence of T-reg lymphocyte recirculation in-between these ectopic adipose depots.

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