Toll-like receptors in the uterus, cervix, and placenta: is pregnancy an immunosuppressed state?

Abstract

These studies were performed to elucidate the expression of Toll-like receptors (TLRs) in the uterus, cervix, and placenta in pregnancy and across gestation. Message expressions of TLR-2, -3, -4, and -9 were investigated in nonpregnant mice and across gestation in CD-1 mice. Uterine, cervical, and placental tissues were harvested, and RNA was extracted. Quantitative polymerase chain reaction was performed. Messenger RNA expression of TLRs is significantly upregulated in pregnant uterine and cervical tissues. There is differential TLR messenger RNA expression between the uterus, cervix, and placenta. In the placenta, TLR 4 is significantly downregulated. These findings suggest that the innate immune system is a dynamic system during gestation. The concept of immunosuppression during pregnancy appears to be valid in the placenta only in regard to TLR expression. Research is warranted to determine whether the upregulation in the uterus and cervix during pregnancy is associated with an increased likelihood of responding to a pathogen or serve as a protective mechanism or both.