IL6 and infection: Calcitriol regulates placental immune response and inflammation in maternal uterine natural killer (uNK) cells by inhibiting inflammatory cytokines (TNF-α, IL-6) produced by trophoblast cells to reduce inflammation and produced by decidual cells in the maternal endometrium for immunosuppression as well as promoting the release of antimicrobial peptides (hCTD, HBD2, HBD3) to restrain infection [21].