Human Milk Oligosaccharides Increase Mucin Expression in Experimental Necrotizing Enterocolitis

Abstract

Scope Necrotizing enterocolitis (NEC) is a leading cause of morbidity and death in preterm infants, occurring more often in formula‐fed than breastfed infants. Studies in both rats and humans show that human milk oligosaccharides (HMOs) lower the incidence of NEC, but the mechanism underlying such protection is currently unclear. Methods and Results By extracting HMOs from pooled human breastmilk, the impact of HMOs on the intestinal mucin levels in a murine model of NEC are investigated. To confirm the results, the findings are validated by exposing human intestinal epithelial cells and intestinal organoids to HMOs and evaluated for mucin expression. HMO‐gavage to pups increases Muc2 levels and decreases intestinal permeability to macromolecular dextran. HMO‐treated cells have increased Muc2 expression, decreased bacterial attachment and dextran permeability during challenge by enteric pathogens. To identify the mediators involved in HMO induction of mucins, it is demonstrated that HMOs directly induce the expression of chaperone proteins including protein disulfide isomerase (PDI). Suppression of PDI activity removes the protective effects of HMOs on barrier function in vitro as well as NEC protection in vivo. Conclusions Taken together, the results provide insights to the possible mechanisms by which HMOs protect the neonatal intestine through upregulation of mucins.

Human Milk Oligosaccharides Differently Modulate Goblet Cells Under Homeostatic, Proinflammatory Conditions and ER Stress

“…Pooled mixtures of hMOs isolated from mother milk have been reported to support the intestine barrier function by increasing mucin expression . Here, we studied the modulatory effects of individual commonly present hMOs in mother milk, i.e., 2′‐FL, 3‐FL, and its acid hydrolysis product LNT2 on expression of goblet cell secretory related genes MUC2 , TFF3 , and RETNLB , and the Golgi‐sulfotransferase genes CHST5 and GAL3ST2 in goblet cells.…”

“…The latter, gut barrier function, is provided by tightly connected epithelial cells and mucus. hMOs are known to enhance epithelial barrier, but the relative effects of individual oligosaccharides on stimulate mucus function have not been studied yet. HMOs are also subject to modifications during passage through the gastrointestinal tract.…”

Necrotizing Enterocolitis: State of the Art in Translating Experimental Research to the Bedside

“…Wu et al developed neonatal intestinal organoid cultures derived from normal ileal biopsies from preterm infants undergoing laparotomy to resect NEC structures. 23 In this study, we demonstrated that treatment of human neonatal intestinal organoids with HMOs led to increased crypt budding and increased mRNA expression of mucin (Muc2). This indicates a direct role of HMOs in increasing mucin expression in experimental NEC.…”

“…22 Wu et al have also used the human-derived mucus-secreting cell lines LS174T and Caco-2Bbe1 to validate a direct role for human milk oligosaccharides (HMOs) in increasing mucin expression, as HMOs protect the neonatal intestine during experimental NEC through upregulation of mucin. 23 Taken together, in vitro models of intestinal epithelial injury are advantageous as they allow us to observe cell proliferation, apoptosis, and gene expression among other factors. These in vitro models have the advantage of overcoming the difficulty in identifying cellular and molecular contributors to disease and to independently modifying them in the whole-animal in vivo models.…”

“…This indicates a direct role of HMOs in increasing mucin expression in experimental NEC. 23 Ares et al have also reported a human epithelial model of NEC that involves culturing human organoids after isolation of intestinal stem cells from patients undergoing bowel resection. 37 The authors demonstrate that administration of LPS in the growth media of organoids leads to changes in histology, genetic and protein expression, as well as an inflammatory response resembling human NEC including increased mRNA and protein expression of TLR4.…”