Bacterial Imprinting of the Neonatal Immune System via Breast Milk

Pablo F. Perez1,4, Joël Doré2, Marion Leclerc2, Florence Levenez2, Jalil Benyacoub1, Patrick Serrant1, Iris Segura-Roggero1, Eduardo J. Schiffrin1,3 & Anne Donnet-Hughes1
1Nestec Ltd, Nestlé Research Centre, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland ; 2 National Institute for Agronomic Research, Unit for Ecology and Physiology of the Digestive Tract, 78352 Jouy-en-Josas Cedex, France; 3Present address:  Nestlé Nutrition, Nestec Ltd., Avenue Reller 22, 1800 Vevey, Switzerland; 4Present address: Centro de Investigación y Desarrollo en Criotecnología de Alimentos - Cátedra de Microbiología, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata (1900), Argentina.

An essential feature of a healthy, intestinal immune system is the ability to discriminate and respond appropriately to the wide spectrum of microorganisms interacting with the intestinal mucosa.  One of the first challenges to this system occurs immediately after birth when a large number of externally derived microbes attempt to colonize the sterile, immature gut. Remarkably, the inexperienced immune system already distinguishes between the diverse microbes and allows colonization by commensal microorganisms and an active response to eliminate potential pathogens. Furthermore, the microbiota is established in the absence of any detrimental inflammatory process.  Clearly, strong regulatory mechanisms are already in force.  However, the observation that breast-fed infants have a different intestinal microbiota and a lower incidence of infection and disease than formula-fed infants, suggest that additional regulation is mediated postnatally by breast milk. 

Several studies have described the presence of commensal bacteria in maternal milk.  The majority of these are considered to be contaminants from the mother’s skin or the infant’s mouth but some authors suggest that certain milk bacteria colonize the neonatal intestine and provide protection. Our research examines breast milk factors which may educate the neonatal immune system to distinguish between commensals and pathogens and influence the process of colonization.  The presentation will cover our recent work examining a natural bacterial inoculum in breast milk.  Although the relevance of this inoculum to the mother or to the suckling neonate is not known, a potential contribution to neonatal immune instruction will be considered.