Dynamics of immune cells in the fetal brain upon viral inflammation

Newswise — The fetal immune system undergoes many developmental milestones, with several immune cell subsets emerging during pregnancy. Recent evidence has shown that maternal infections during pregnancy can influence offspring immunity in the long term . Moreover, maternal infections are associated with an increased risk for neurodevelopmental disorders in the offspring. Yet, our knowledge of the immune cell dynamics in the fetal brain throughout gestation and their response to inflammation remains limited. We sought to characterize the phenotype of immune cells in murine implantation sites at mid-gestation, a time point equivalent to the beginning of the second trimester in humans. Our preliminary studies revealed specific and robust populations of maternal and fetal immune cells in murine fetal brains. Quite unexpectedly, one of these populations expressed NK1.1, a marker for natural killer cells and innate lymphoid cells. Given that the presence of maternal and fetal NK1.1+ cells in the fetal brains at mid-gestation has not been previously reported, our goal is to determine the phenotype and kinetics of the maternal and fetal NK1.1+ immune cells in the fetal brain during a healthy pregnancy and upon congenital infection. To address this, I will use a high-dimensional sequencing technology, CITE-seq, that allows me to simultaneously study surface markers and gene expression of cells. Maternal immune responses critically impact fetal development during gestation and have long-term health outcomes in offspring. Understanding maternal and fetal immune responses to inflammation will inform the origin of fetal inflammation-driven neurodevelopmental disorders and ultimately improve offspring's health outcomes.