Influence of maternal microbiota during pregnancy on infant immunity

Abstract

Microbiota from various maternal sites, including the gut, vagina and breast milk, are known to influence colonization in infants. However, emerging evidence suggests that these sites may exert their influence prior to delivery, in turn influencing fetal immune development. The dogma of a sterile womb continues to be challenged. Regardless, there is convincing evidence that the composition of the maternal gut prior to delivery influences neonatal immunity. Therefore, while the presence and function of placental microbiome is not clear, there is consensus that the gut microbiota during pregnancy is a critical determinant of offspring health. Data supporting the notion of bacterial translocation from the maternal gut to extra-intestinal sites during pregnancy are emerging, and potentially explain the presence of bacteria in breast milk. Much evidence suggests that the maternal gut microbiota during pregnancy potentially determines the development of atopy and autoimmune phenotypes in offspring. Here, we highlight the role of the maternal microbiota prior to delivery on infant immunity and predisposition to diseases. Moreover, we discuss potential mechanisms that underlie this phenomenon.

Keywords: infant immunity; microbiota; pregnancy.

Figure 1

Experimental model of the impact of maternal gut microbiota during gestation on offspring immunity. To test the role of maternal gut microbiota during gestation on offspring immunity, pregnant BALB/c dams were fed vancomycin in drinking water for 5 days prior to delivery. No antibiotics were administered to control dams. All mice in these groups received normal water after delivery. Pups born to dams treated with vancomycin during gestation only had altered intestinal microbiota compared to controls. In addition, pups born to vancomycin breeders had significantly higher splenic cell counts, higher numbers of total B cells as well as follicular B cells versus control pups 1 .

Figure 2

Potential mechanisms of crosstalk between maternal microbiota and offspring immunity. Maternal gut microbiota during pregnancy translocate to the maternal‐fetal interface. Commensals microbes translocate from the maternal gut to the placenta or fetal gut during pregnancy (maternal gut placenta axis) or to mammary glands. These microbes impact developing fetal immunity via various mechanisms including epigenetic changes, release of short chain fatty acids and alteration of the cytokine environment. Bacteria or bacterial metabolites transfer to the mammary glands (gut‐breastmilk axis) impacting infant gut colonization and continued immune development after delivery.