UC San Diego

Pregnancy causes many changes within the maternal immune system that are essential to foster a healthy environment for the fetus to develop. Maternal obesity is an increasingly recognized factor that can disrupt the delicate immunological processes at the feto- maternal interface. This study uses single cell (sc) RNA sequencing on cells extracted from three compartments of placental tissue (placental villi, basal plate, and chorioamniotic membrane) as well as maternal and cord blood of obese and lean pregnant individuals. Bioinformatics analyses were employed to determine differences in the immune composition of the maternal and cord blood, the three compartments of the placenta, and obese and lean individuals. Maternal blood had higher proportions of natural killer T (NKT) cells than cord blood (0.09486 vs 0.008528), but was not significant after multiple testing correction (nominal P value = 0.039). The placental compartments differed in their proportions of CD8+ T cells (nominal P value = 0.0125) and NK cells (nominal P value = 0.0269), emphasizing the different roles that each compartment plays in pregnancy, although not significant after multiple testing correction. Macrophages and monocytes were more abundant in obese individuals’ blood; interestingly, only the macrophages were more abundant in the placental tissue, although not significant after multiple testing correction. Pathway analysis of significant differentially expressed genes revealed important regulated functions of these macrophages during pregnancy such as immune defense response and response to external stimuli.