Relationships Between Phenotype and Function of Blood CD4+ T-Cells and Ascending Thoracic Aortic Aneurysm: an Experimental Study

Abstract

Introduction Non-familial ascending thoracic aorta dilation and aneurysms (TAAs) are silent diseases in elderly patients. Histopathology revealed that functionally polarized infiltrating CD4 + T-cells play a key role in aortic wall weakening. Objective To evaluate the possible associations between phenotype and cytokine production of circulating CD4 + T-lymphocytes and the presence of TAA in patients with aortic valve disease (AVD). Methods We studied blood samples from 10 patients with TAA and 10 patients with AVD. Flow cytometry was used to quantify: a) CD4 + T-lymphocytes surface expression of CD25, CD28, and chemokine receptors (CCR5, CXCR3, CX3CR1); b) fractions of in vitro stimulated CD4 + T-cells producing cytokines (interferon gamma [IFN-γ], interleukin [IL]-17A, IL-21, IL-10); c) CD4 + CD25 high FoxP3 + regulatory T-cells (Treg) fraction. Enzyme-linked immunosorbent assays (ELISA) were performed for cytokines (IFN-γ, IL-6, IL-10, IL-17A, IL-23, transforming growth factor beta [TGF-β]) and chemokines (RANTES, CX3CL1). Results The total CD4 + CD28 ± CD4 + /CX3CR1 + T-cells fraction was higher ( P =0.0323) in AVD (20.452±4.673) than in TAA patients (8.633±2.030). The frequency ratio of CD4 + T-lymphocytes producing IFN-γ vs . IL-17A+IL-21 cytokine-producing CD4+ T-cells was higher ( P =0.0239) in AVD (2.102±0.272) than in TAA (1.365±0.123) patients. The sum of CD4 + CD28 ± CD4 + /CX3CR1 + T-cells correlated positively with values of the previous cytokine ratio ( P =0.0002, R=0.732). The ratio of CD4 + CD28 ± CD4 + /CX3CR1 + T-cells vs . Treg was higher ( P =0.0008) in AVD (20.859±3.393) than in TAA (6.367±1.277) patients. Conclusion Our results show that the presence of TAA in subjects with AVD is associated with imbalance between phenotypic and cytokine-producing subsets of circulating CD4+ T-lymphocytes, prevalently oriented towards a pro-fibrotic and IFN-γ counteracting effect to functional polarization.