miR-23a-mediated TRF2 repression in CD4 T cells from PLWH.

CD4 T cells in people living with HIV (PLWH) on antiretroviral therapy (ART) often exhibit an inflammaging phenotype, characterized by persistent inflammation, immune activation, exhaustion, senescence, and apoptosis. We have previously demonstrated that inhibition of telomeric repeat factor 2 (TRF2) protein causes accelerated telomere erosion and premature CD4 T cell aging in PLWH. In this study, we further investigated how TRF2 protein is inhibited in CD4 T cells from PLWH, focusing on the miRNA-mediated mechanism. We found that miR-23a is significantly increased, whereas TRF2 protein is repressed, in CD4 T cells from PLWH compared to healthy subjects (HS). Bioinformatics analysis revealed that the TRF2 3'UTR is a potential target of miR-23a. Co-transfection of miR-23a with a luciferase construct containing TRF2 3'UTR into HEK293T cells revealed that miR-23a suppresses TRF2 protein translation. Notably, T cell receptor (TCR) activation in CD4 T cells from both PLWH and HS increased miR-23a and decreased TRF2 protein expression. Furthermore, increasing miR-23a in CD4 T cells from HS led to a decrease in TRF2 protein level and an increase in cellular apoptosis - a phenotype similar to what we observed in PLWH. Moreover, the knockdown of miR-23a in CD4 T cells from PLWH increased TRF2, but not TRF1, protein levels. These results suggest that miR-23a negatively regulates TRF2 protein expression in CD4 T cells; thus, targeting miR-23a may increase TRF2 protein level, and thereby protect telomere integrity and restore CD4 T cell functions in PLWH.