Placental Immune Responses to Viruses: Molecular and Histo-Pathologic Perspectives

As most recently demonstrated by the SARS-CoV-2 pandemic, congenital and perinatal infections are of significant concern to the pregnant population as compared to the general population. These outcomes can range from no apparent impact all the way to spontaneous abortion or fetal infection with long term developmental consequences. While some pathogens have developed mechanisms to cross the placenta and directly infect the fetus, other pathogens lead to an upregulation in maternal or placental inflammation that can indirectly cause harm. The placenta is a temporary, yet critical organ that serves multiple important functions during gestation including facilitation of fetal nutrition, oxygenation, and prevention of fetal infection in utero. Here, we review trophoblast cell immunology and the molecular mechanisms utilized to protect the fetus from infection. Lastly, we discuss consequences in the placenta when these protections fail and the histopathologic result following infection.

Automated summary

Congenital and perinatal infections pose significant risks to pregnant women, potentially leading to fetal infection and long-term developmental consequences. Some pathogens can directly infect the fetus by crossing the placenta, while others induce maternal or placental inflammation that indirectly harms the fetus. The placenta is a temporary but critical organ that plays vital roles in facilitating fetal nutrition, oxygenation, and protection against in utero infection.