Human breast milk enhances intestinal mucosal barrier function and innate immunity in a pediatric human enteroid model

Abstract

Breastfeeding has been associated with long lasting health benefits. Nutrients and bioactive components of human breast milk promote cell growth, immune development, and shield the infant gut from insults and microbial threats. The molecular and cellular events involved in these processes are ill defined. We have established human pediatric enteroids and interrogated maternal milk's impact on epithelial cell maturation and function in comparison with commercial infant formula. Colostrum applied apically to pediatric enteroid monolayers reduced ion permeability, stimulated epithelial cell differentiation and enhanced tight junction function by upregulating occludin expression. Breast milk heightened the production of antimicrobial peptide alpha-defensin 5 by goblet and Paneth cells, and modulated cytokine production abolishing apical release of pro-inflammatory GM-CSF. These attributes were not found in commercial infant formula. Epithelial cells exposed to breast milk elevated apical and intracellular pIgR expression and enable maternal IgA translocation. Proteomic data revealed a breast milk-induced molecular pattern associated with tissue remodeling and homeostasis. Using a novel ex vivo pediatric enteroid model, we have identified cellular and molecular pathways involved in human milk-mediated improvement of human intestinal physiology and immunity.

Infant and Adult Human Intestinal Enteroids are Morphologically and Functionally Distinct

“…Other morphological characteristics of infant HIEs such as shorter epithelial cell height and higher proliferation also reflect features of a developing infant intestinal epithelium. Shorter epithelial cell height is described as a marker of intestinal immaturity and has been reported in duodenal biopsies of infants (45) and more recently, duodenal pediatric HIEs (25). Increased proliferation within the intestinal crypt contributes to crypt hyperplasia and is a potential indicator of an immature intestinal epithelium (46).…”

“…Promising therapies to decrease the risk of NEC involves improving barrier function in the infant gut using growth factors (57,58), breast milk and its bioactives (59), and probiotics (60)(61)(62). Indeed, a previous study using duodenal HIEs from a two-year-old and five-year-old child showed that colostrum enhanced epithelial barrier function and breast milk increased the production of alpha defensin 5 (25).…”

“…Addition of breast milk was also shown to increase cell height and promote growth of these pediatric duodenal HIEs (25). While we did not directly evaluate the effects of breast milk on infant and adult HIEs, we examined genes involved in the metabolism of lactose and fats, the two most abundant solid components in human breast milk (50,63).…”

“…Human fetal tissue-derived enteroids have also been used to study the pathogenesis of different infectious agents (18,19) and for diseases such as NEC (24). Currently, there are only a limited number of studies using HIEs from infants and young children and very few systematic comparisons have been made between the different models (25,26). Characteristics of fetal HIEs correlate with their developmental age and demonstrate immature metabolic and host-defense functions compared to adult HIEs (24,27).…”

“…Differences in transcriptional responses between adult and preterm enteroids to Enterococcus faecalis have been described (26). A study using HIEs from 2-and 5-year-old children showed significantly shorter enterocyte cell height and lower transepithelial electrical resistance (TEER) than adult HIEs (25). Fundamental differences between fetal, infant, and adult gastrointestinal tracts raise questions on whether adult and fetal HIEs adequately model the infant gastrointestinal epithelium.…”