Unique maternal immune and functional microbial profiles during prenatal stress

Maternal stress during pregnancy is widespread and stress-induced fetal neuroinflammation is thought to derive from a disruption in intrauterine immune homeostasis, though the exact origins are incompletely defined. We aimed to identify divergent immune and microbial metagenome profiles of stressed gestating mice that may underlie detrimental inflammatory signaling at the maternal-fetal interface. In response to stress, maternal glucocorticoid circuit activation corresponded with diminished spleen mass and IL-1β production, reflecting systemic immunosuppression. At the maternal-fetal interface, density of placental mononuclear leukocytes decreased with stress. Yet maternal whole blood leukocyte analysis indicated monocytosis and classical M1 phenotypic shifts. Genome-resolved microbial metagenomic analyses revealed reductions in genes, microbial strains, and metabolic pathways in stressed dams that are primarily associated with pro-inflammatory function. Overall, these data indicate that stress disrupts maternal immunological and microbial regulation during pregnancy, characterized by concurrent anti- and pro-inflammatory signatures, which may displace immune equilibrium at the maternal-fetal interface.