Shaping the Gut Microbiota by Breastfeeding: The Gateway to Allergy Prevention?

Abstract

Evidence is accumulating that demonstrates the importance of the gut microbiota in health and diseases such as allergy. Recent studies emphasize the importance of the "window of opportunity" in early life, during which interventions altering the gut microbiota induce long-term effects. The neonate's gut microbiota composition and metabolism could therefore play an essential role in allergic disease risk. Breastfeeding shapes the gut microbiota in early life, both directly by exposure of the neonate to the milk microbiota and indirectly, via maternal milk factors that affect bacterial growth and metabolism such as human milk oligosaccharides, secretory IgA, and anti-microbial factors. The potential of breastmilk to modulate the offspring's early gut microbiota is a promising tool for allergy prevention. Here, we will review the existing evidence demonstrating the impact of breastfeeding on shaping the neonate's gut microbiota and highlight the potential of this strategy for allergy prevention.

Keywords: allergy; breastmilk; gut microbiota; neonate; prevention.

Figure 1

The potential of breastmilk to prevent allergic disease by shaping of the neonatal gut microbiota. Breastmilk contains microbes as well as factors that indirectly shape the gut microbiota of the neonate. Breastmilk can direct the early microbiota composition, i.e., favor the growth of Bifidobacteria and Lactobacillus, and affect microbiota metabolic function, which subsequently can impact on immune development and maturation. The gut microbiota in early life impacts on immune maturation via microorganism-associated molecular patterns (MAMPs) signaling (not shown in the figure) and via microbiota metabolites such as short-chain fatty acids (SCFA) and aryl hydrocarbon receptor (AHR) ligands. The gut microbiota of the neonate can direct the immune system toward allergy prevention via the induction of FoxP3+ regulatory T cells (Treg), which contribute to oral tolerance induction, and IL-22 production by group 3 innate lymphoid cell (ILC3) which strengthens the gut barrier. As a result, shaping of the infant's gut microbiota by breastmilk has the potential to direct the immune system toward allergy prevention. TGF-β, Transforming Growth Factor beta; IDO, indoleamine 2,3-dioxygenase.