Aging impacts CD103+CD8+ T cell presence and induction by dendritic cells in the genital tract

Summary As women age, susceptibility to systemic and genital infections increases. Tissue‐resident memory T cells (TRMs) are CD103+CD8+ long‐lived lymphocytes that provide critical mucosal immune protection. Mucosal dendritic cells (DCs) are known to induce CD103 expression on CD8+ T cells. While CD103+CD8+ T cells are found throughout the female reproductive tract (FRT), the extent to which aging impacts their presence and induction by DCs remains unknown. Using hysterectomy tissues, we found that endometrial CD103+CD8+ T cells were increased in postmenopausal compared to premenopausal women. Endometrial DCs from postmenopausal women were significantly more effective at inducing CD103 expression on allogeneic naïve CD8+ T cells than DCs from premenopausal women; CD103 upregulation was mediated through membrane‐bound TGFβ signaling. In contrast, cervical CD103+ T cells and DC numbers declined in postmenopausal women with age. Decreases in DCs correlated with decreased CD103+ T cells in endocervix, but not ectocervix. Our findings demonstrate a previously unrecognized compartmentalization of TRMs in the FRT of postmenopausal women, with loss of TRMs and DCs in the cervix with aging, and increased TRMs and DC induction capacity in the endometrium. These findings are relevant to understanding immune protection in the FRT and to the design of vaccines for women of all ages.