Background: Abnormal CD4+ T cells appear in the peripheral blood of patients with acute coronary syndrome (ACS). Studies have confirmed that CD4+ T cells are resistant to apoptosis, but the specific mechanism has not been elucidated yet.
Objectives: The microRNA (miR)-let-7i plays an important regulatory role in the cardiovascular system and is widely involved in cell proliferation and apoptosis. In this study, we aimed to investigate its functional and regulatory roles in CD4+ T cell apoptosis.
Material and methods: Apoptosis of CD4+ T cells was detected using TUNEL assay. Western blot analyses were used to detect the expression of Bcl-2 and Bax. Real-time polymerase chain reaction and western blot analyses were used to detect the expression of miR-let-7i, Fas and FasL. A miR-let-7i mimic or inhibitor was transfected into CD4+ T cells, and miR-let-7i activity was investigated using Cell Counting Kit-8 (CCK-8) and TUNEL assays.
Results: Apoptosis of CD4+ T cells in ACS patients was significantly decreased. Overexpression of miR-let-7i inhibited CD4+ T cell apoptosis and improved cell survival rates, while inhibition of miR-let-7i facilitated cell apoptosis. We also found that miR-let-7i negatively regulated Fas and FasL gene expression in CD4+ T cells.
Conclusions: The present study identified that miR-let-7i significantly reduces Fas and FasL expression in ACS CD4+ T cells and inhibits apoptosis in these cells. Therefore, miR-let-7i may serve as a possible therapeutic target for the treatment of ACS.
Keywords: CD4+ T cell; Fas; FasL; apoptosis; miR-let-7i.