Microbial ecology and host-microbiota interactions during early life stages

Abstract

The role of human microbiota has been redefined during recent years and its physiological role is now much more important than earlier understood. Intestinal microbial colonization is essential for the maturation of immune system and for the developmental regulation of the intestinal physiology. Alterations in this process of colonization have been shown to predispose and increase the risk to disease later in life. The first contact of neonates with microbes is provided by the maternal microbiota. Moreover, mode of delivery, type of infant feeding and other perinatal factors can influence the establishment of the infant microbiota. Taken into consideration all the available information it could be concluded that the exposure to the adequate microbes early in gestation and neonatal period seems to have a relevant role in health. Maternal microbial environment affects maternal and fetal immune physiology and, of relevance, this interaction with microbes at the fetal-maternal interface could be modulated by specific microbes administered to the pregnant mother. Indeed, probiotic interventions aiming to reduce the risk of immune-mediated diseases may appear effective during early life.

Figure 1. Factors influencing early microbiota colonization and its impact on infant health. Neonatal bacterial colonization is determined by environmental factors (e.g., maternal environment and diet) combined with host influences (genetics and gut characteristics). Maternal microbial environment affects maternal and fetal immune physiology and, of relevance, this interaction with microbes at the fetal-maternal interface could be modulated by specific microbes administered to the pregnant mother and/or neonates. The genetically-determined gut characteristics (structure, function, immunity), and the time and mode of birth (preterm, term, cesarean, vaginal), are crucial factors as well as maternal microbiota and nutritional status together diet (parenteral nutrition, formula, breast milk, and also, use of probiotics, prebiotics and/or antibiotics).

Figure 2. Perinatal and postnatal probiotic interventions and their potential benefits for infant development and health. Early modulation driving healthy microbiota would be the aim of probiotic therapy and opens new prevention and treatment possibilities of diseases in which alteration of the microbiota plays relevant roles. Several studies have shown that administration of probiotics to pregnant women, nursing mothers, or newborns can influence the establishment and composition of infant gut microbiota and also, the development and maturation of immune system impacting early and later in life. NEC, necrotizing enterocolitis.