Characterization and functional elucidation of CD8+AT2+ lymphocytes in human thoracic aortic aneurysm

Human thoracic aortic aneurysm (TAA) is one of the most fatal cardiovascular diseases. However, the underlying molecular mechanism behind this disease remains uncertain. Previous studies have proven the importance of angiotensin II receptor type 2 (AT2) and endothelial cells in aneurysm pathology. This study aimed to elucidate the effect of CD8+AT2+ lymphocytes in TAA pathogenesis. The expression levels of CD8, AT2, IL-2, and IFN-r were determined by real-time quantitative PCR. CD8+AT2+ lymphocytes were counted by semi-quantitative immunofluorescence and flow cytometric analysis. The wound-healing assay was used to detect endothelial cell migration. The expression levels of CD8 and AT2 in human nonsyndromic TAA tissues were significantly higher than those of the control. TAA tissues have more CD8+AT2+ lymphocytes than the controls. Furthermore, circulating CD8+AT2+ lymphocytes were significantly elevated in TAA patients. The expression levels of IL-2 and IFN-r in CD8+AT2+ lymphocytes were significantly increased compared with those in CD8+AT2- lymphocytes. The CD8+AT2+ lymphocytes had a greater inhibitory effect on endothelial migration compared with CD8+AT2- cells. Our findings showed that the increment of CD8+AT2+ lymphocytes in human TAA exhibited a protective effect by downregulating the release of pro-inflammation cytokines and the inhibition of endothelial cell migration.