Aging is accompanied by a decrease in the number of naive Tregs

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background. Age-related changes in the immune system are an important factor contributing to the maintenance of chronic inflammatory status. There are undoubted data on the decrease of the number of T-lymphocytes with age caused by thymus involution, but there are currently no unambiguous data on changes of minor T-cell subpopulations, in particular, regulatory T-cells (Treg). The aim of this study was to analyze the content of effector and regulatory CD4+ T cell subsets in patients with coronary and/or carotid atherosclerosis depending on age. Methods. 111 patients (men, median age 63 (55;69)) with coronary and/or carotid atherosclerosis, without smoking anamnesis, were enrolled. Mononuclear leuocytes were isolated from blood by gradient centrifugation, and CD4 + CD25high and CD4 + Foxp3+ Treg, CD4 + IL17+ T-helpers (Th) 17 and CD4 + INFγ Th1 were evaluated by direct immunofluorescence and flow cytometry. For intracellular cytokine detection cells were pre-activated in vitro in the presence of PMA/ionomycin/brefeldin A. In 74 patients cells were additionally stained with CD39, CD278, CD45RA Mabs to reveal naïve and primed T-cells. Results. According to age the patients formed three groups: I – <55 y.o. (n = 23), II – 55-64 y.o. (n = 42), III - ≥65 y.o. (n = 46). All patients were taking statins at baseline. The groups were comparable in traditional risk factors of CVD (BMI, arterial hypertension, diabetes mellitus, previous myocardial infarction anamnesis). The absolute content of CD4+ T cells was lower in group III (646.3 (516.0;806.4)) compared to groups I (903.0 (585.6;1113.8), p = 0.03) and II (745.4 (502.2;924.0), p = 0.06). The absolute content of CD4 + CD25high Treg was lower in group III (24.2 (18.4;35.2)) compared to groups I (35.0 (28.7;54.4), p = 0.01) and II (31.0 (21.1;43.6), p = 0.03). There were no differences in Th1, Th17, CD39 + CD45RA- and CD278+ Treg content between groups. A negative correlation was found between age and the content of CD4+ T cells (r= -0.28), CD4 + CD25high Treg (r= -0.27), p < 0.05. A negative correlation was found between age and CD4 + CD25highCD45RA+ Treg (r= -0.24) and CD4 + CD45RA+ T cells (r= -0.36), CD4 + CD45RA+/CD4 + CD45RA- T-cells ratio (r= -0.24), p < 0.05. Conclusion. Here we demonstrate an age-dependent decrease of total CD4+ T cell population and Treg subset in patients with atherosclerosis. The changes observed were primary due to the deficiency of CD45RA+ naïve T cells. The effector cell Th1 and Th17 quantities were at the same levels. Future research will show whether the identified immunological patterns can contribute to the progression of atherosclerosis and other chronic inflammatory diseases.