137 - Standing in the Gap of Neonatal Microbe-host Barrier Function

Abstract: The provision of mammary secretions in the form of colostrum and mature milk for newborns is an essential survival function that has evolved over millennia in mammalian species. Colostrum serves a vital function for neonates by providing nutrients for energy and growth as they transition from placental nutrition to oral ingestion of more complex macromolecules, including lactose, proteins, and triglycerides. Colostrum also provides critical immune protection from colonizing commensal and pathogenic microbes that supports neonatal immunity until maturation of the immune system. This concept of homologous passive immunity conferred by colostrum is well known in farm animal species and has been largely attributed to immunoglobulins transferred from mother to offspring. Heterologous passive immunity is also an approach whereby bovine colostrum obtained from normal or hyperimmunized cows is used therapeutically to prevent specific GI diseases in swine and human infants. The critical importance of colostrum to survival of newborn farm animals also holds true in the prevention of intestinal diseases, such as necrotizing enterocolitis (NEC), in hospitalized premature infants.  In preterm infants, mother’s own milk may not always be available and infants are instead fed donor human milk, which provides effective protection against NEC.  Whether the benefits of human milk in the prevention of NEC are due to immunoglobulins is not well established.  These scenarios whereby colostrum from different species or different mothers within a species protect the neonatal gut point to common elements of host protection.  New experimental approaches and tools are being applied to understanding the molecular mechanism of how components of maternal milk impact gut microbial colonization and interaction with the host immune system.