Infection of Placental Extravillous Cytotrophoblasts with Human Cytomegalovirus Causes a Treg/Th17 Imbalance at the Maternal–Fetal Interface

This paper aimed to evaluate whether human cytomegalovirus (HCMV) infection in extravillous cytotrophoblasts (EVT) could shift the balance between regulatory T (Treg) and T-helper type 17 (Th17) cells in vitro. In this study, primary EVT isolated from first trimester placental tissues were infected with HCMV, and conditional media were harvested after cultivation for 72 h. T lymphocytes were cultured in the presence or absence of HCMV-infected conditional media. The frequencies of Th17 or Treg cells from HCMV group were significantly lower or higher than those from the control group, with the expression of corresponding key cytokines at both messenger ribonucleic acid and secretion levels, respectively. The ratio of Treg to Th17 cells was significantly lower in HCMV group than that in control group (P < 0.01). In conclusion, tiled Th17/Treg balance at maternal–fetal interface exists after HCMV infection.