Department of Immunology, Research Center on Pediatric Development and Diseases, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, State Key Laboratory of Medical Molecular Biology, 100005, Beijing, China. [Email]
As an important component of innate immunity, human circulating γδ T cells function in rapid responses to infections and tumorigenesis. MicroRNAs (miRNAs) play a critical regulatory role in multiple biological processes and diseases. Therefore, how the functions of circulating human γδ T cells are regulated by miRNAs merits investigation. In this study, we profiled the miRNA expression patterns in human peripheral γδ T cells from 21 healthy donors and identified 14 miRNAs that were differentially expressed between peripheral αβ T cells and γδ T cells. Of the 14 identified genes, 7 miRNAs were downregulated, including miR-150-5p, miR-450a-5p, miR-193b-3p, miR-365a-3p, miR-31-5p, miR-125b-5p and miR-99a-5p, whereas the other 7 miRNAs were upregulated, including miR-34a-5p, miR-16-5p, miR-15b-5p, miR-24-3p, miR-22-3p, miR-22-5p and miR-9-5p, in γδ T cells compared with αβ T cells. In subsequent functional studies, we found that both miR-125b-5p and miR-99a-5p downregulated γδ T cell activation and cytotoxicity to tumor cells. Overexpression of miR-125b-5p or miR-99a-5p in γδ T cells inhibited γδ T cell activation and promoted γδ T cell apoptosis. Additionally, miR-125b-5p knockdown facilitated the cytotoxicity of γδ T cells toward tumor cells in vitro by increasing degranulation and secretion of IFN-γ and TNF-α. Our findings improve the understanding of the regulatory functions of miRNAs in γδ T cell activation and cytotoxicity, which has implications for interventional approaches to γδ T cell-mediated cancer therapy.