Breast milk is the perfect nutrition for infants, a result of millions of years of evolution. In addition to providing a source of nutrition, breast milk contains a diverse array of microbiota and myriad biologically active components that are thought to guide the infant’s developing mucosal immune system. It is believed that bacteria from the mother’s intestine may translocate to breast milk and dynamically transfer to the infant. Such interplay between mother and her infant is a key to establishing a healthy infant intestinal microbiome. These intestinal bacteria protect against many respiratory and diarrheal illnesses, but are subject to environmental stresses such as antibiotic use. Orchestrating the development of the microbiota are the human milk oligosaccharides (HMOs), the synthesis of which are partially determined by the maternal genotype. HMOs are thought to play a role in preventing pathogenic bacterial adhesion though multiple mechanisms, while also providing nutrition for the microbiome. Extracellular vesicles (EVs), including exosomes, carry a diverse cargo, including mRNA, miRNA, and cytosolic and membrane-bound proteins, and are readily detectable in human breast milk. Strongly implicated in cell–cell signaling, EVs could therefore may play a further role in the development of the infant microbiome. This review considers the emerging role of breast milk microbiota, bioactive HMOs, and EVs in the establishment of the neonatal microbiome and the consequent potential for modulation of neonatal immune system development.

Mother's Milk: A Purposeful Contribution to the Development of the Infant Microbiota and Immunity.

Human milk is a dynamic source of nutrients and bioactive factors; unique in providing for the human infant’s optimal growth and development. The growing infant’s immune system has a number of developmental immune deficiencies placing the infant at increased risk of infection. This review focuses on how human milk directly contributes to the infant’s innate immunity. Remarkable new findings clarify the multifunctional nature of human milk bioactive components. New research techniques have expanded our understanding of the potential for human milk’s effect on the infant that will never be possible with milk formulas. Human milk microbiome directly shapes the infant’s intestinal microbiome while the human milk oligosaccharides (HMOs) drive the growth of these microbes within the gut. New techniques such as genomics, metabolomics, proteomics and glycomics are being employed to describe this symbiotic relationship. An expanded role for antimicrobial proteins/peptides (AMPs) within human milk in innate immune protection is described. The unique milieu of enhanced immune protection with diminished inflammation results from a complex interaction of anti-inflammatory and anti-oxidative factors provided by human milk to the intestine. New data supports the concept of mucosal-associated lymphoid tissue and its contribution to the cellular content of human milk. Human milk stem cells (hMSCs) have recently been discovered. Their direct role in the infant for repair and regeneration is being investigated. The existence of these hMSCs could prove to be an easily harvested source of multi-lineage stem cells for the study of cancer and tissue regeneration. As the infant’s gastrointestinal tract and immune system develop there is a comparable transition in human milk over time to provide fewer immune factors and more calories and nutrients for growth. Each of these new findings opens the door to future studies of human milk and its effect on the innate immune system and the developing infant.

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Innate Immunity and Breast Milk.

Objectives:The aim of the study was to evaluate the effects of infant formula supplemented with 2 human milk oligosaccharides (HMOs) on infant growth, tolerance, and morbidity.Methods:Healthy infants, 0 to 14 days old, were randomized to an intact-protein, cow's milk–based infant formula (co

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Effects of Infant Formula With Human Milk Oligosaccharides on Growth and Morbidity: A Randomized Multicenter Trial.

Background Evidence suggests that human milk oligosaccharides (HMOs) provide multiple benefits to infants, including prebiotic effects, gut maturation, antimicrobial activities, and immune modulation Clinical intervention studies with HMOs are required to confirm these benefits in infants Objective Our objective was to investigate the effects of feeding formulas supplemented with the HMO 2'-fucosyllactose (2'-FL) on biomarkers of immune function in healthy term infants Methods We performed a substudy nested within a randomized, double-blind, controlled growth and tolerance study in healthy singleton infants (birth weight ≥2490 g) who were enrolled by 5 d of life and exclusively formula-fed (n = 317) or breastfed (n = 107) from enrollment to 4 mo of age Formula-fed infants were randomly assigned to receive 1 of 3 formulas, all containing 24 g total oligosaccharides/L [control: galacto-oligosaccharides (GOS) only; experimental formulas: GOS + 02 or 10 g 2'-FL/L], and compared with a breastfed reference group For this substudy, blood samples were drawn from infants at 6 wk of age (n = 31-42/group) Peripheral blood mononuclear cells (PBMCs) were isolated for cellular phenotyping and stimulated ex vivo with phytohemagglutinin for proliferation and cell cycle progression or respiratory syncytial virus (RSV) Cytokine concentrations were measured in plasma and in ex vivo-stimulated culture supernatants Results Breastfed infants and infants fed either of the experimental formulas with 2'-FL were not different but had 29-83% lower concentrations of plasma inflammatory cytokines than did infants fed the control formula [interleukin (IL) receptor antagonist (IL-1ra), IL-1α, IL-1β, IL-6, and tumor necrosis factor α (TNF-α)] (P ≤ 005) In ex vivo RSV-stimulated PBMC cultures, breastfed infants were not different than either of the groups fed formula with 2'-FL, but they had lower concentrations of TNF-α (31%) and interferon γ (IFN-γ 54%) (P ≤ 005) and tended to have lower IL-1ra (25%) and IL-6 (38%) (unadjusted P ≤ 005) and IL-1β (30%) (unadjusted P = 006) than did infants fed the control formula Conclusions Our data indicate that infants fed formula supplemented with 2'-FL exhibit lower plasma and ex vivo inflammatory cytokine profiles, similar to those of a breastfed reference group This trial was registered at clinicaltrialsgov as NCT01808105

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Similar to Those Who Are Breastfed, Infants Fed a Formula Containing 2′-Fucosyllactose Have Lower Inflammatory Cytokines in a Randomized Controlled Trial

Human milk oligosaccharides (HMOs) comprise a group of structurally complex, unconjugated glycans that are highly abundant in human milk. HMOs are minimally digested in the gastrointestinal tract and reach the colon intact, where they shape the microbiota. A small fraction of HMOs is absorbed, reaches the systemic circulation, and is excreted in urine. HMOs can bind to cell surface receptors expressed on epithelial cells and cells of the immune system and thus modulate neonatal immunity in the infant gut, and possibly also sites throughout the body. In addition, they have been shown to act as soluble decoy receptors to block the attachment of various microbial pathogens to cells. This review summarizes the current knowledge of the effects HMOs can have on infections, allergies, auto-immune diseases and inflammation, and will focus on the role of HMOs in altering immune responses through binding to immune-related receptors.

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Immunological Effects of Human Milk Oligosaccharides.

Background A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammation through lipopolysaccharide (LPS) binding to intestinal toll-like receptor 4 (TLR4). Breast feeding lowers risk of disease, and human milk modulates inflammation. Objective This study tested whether human milk oligosaccharides (HMOSs) influence pathogenic Escherichia coli -induced interleukin (IL)-8 release by intestinal epithelial cells (IECs), identified specific proinflammatory signalling molecules modulated by HMOSs, specified the active HMOS and determined its mechanism of action. Methods Models of inflammation were IECs invaded by type 1 pili enterotoxigenic E. coli (ETEC) in vitro: T84 modelled mature, and H4 modelled immature IECs. LPS-induced signalling molecules co-varying with IL-8 release in the presence or absence of HMOSs were identified. Knockdown and overexpression verified signalling mediators. The oligosaccharide responsible for altered signalling was identified. Results HMOSs attenuated LPS-dependent induction of IL-8 caused by ETEC, uropathogenic E. coli , and adherent-invasive E. coli (AIEC) infection, and suppressed CD14 transcription and translation. CD14 knockdown recapitulated HMOS-induced attenuation. Overexpression of CD14 increased the inflammatory response to ETEC and sensitivity to inhibition by HMOSs. 2′-fucosyllactose (2′-FL), at milk concentrations, displayed equivalent ability as total HMOSs to suppress CD14 expression, and protected AIEC-infected mice. Conclusions HMOSs and 2′-FL directly inhibit LPS-mediated inflammation during ETEC invasion of T84 and H4 IECs through attenuation of CD14 induction. CD14 expression mediates LPS-TLR4 stimulation of portions of the ‘macrophage migration inhibitory factors’ inflammatory pathway via suppressors of cytokine signalling 2/signal transducer and activator of transcription 3/NF-κB. HMOS direct inhibition of inflammation supports its functioning as an innate immune system whereby the mother protects her vulnerable neonate through her milk. 2′-FL, a principal HMOS, quenches inflammatory signalling.

https://gut.bmj.com/content/gutjnl/65/1/33.full.pdf

The human milk oligosaccharide 2′-fucosyllactose modulates CD14 expression in human enterocytes, thereby attenuating LPS-induced inflammation

Background A major cause of enteric infection, Gram-negative pathogenic bacteria activate mucosal inflammation through lipopolysaccharide (LPS) binding to intestinal toll-like receptor 4 (TLR4). Breast feeding lowers risk of disease, and human milk modulates inflammation. Objective This study tested whether human milk oligosaccharides (HMOSs) influence pathogenic Escherichia coli-induced interleukin (IL)-8 release by intestinal epithelial cells (IECs), identified specific proinflammatory signalling molecules modulated by HMOSs, specified the active HMOS and determined its mechanism of action. Methods Models of inflammation were IECs invaded by type 1 pili enterotoxigenic E. coli (ETEC) in vitro: T84 modelled mature, and H4 modelled immature IECs. LPSinduced signalling molecules co-varying with IL-8 release in the presence or absence of HMOSs were identified. Knockdown and overexpression verified signalling mediators. The oligosaccharide responsible for altered

Samuel B Feinberg

Papers

The human milk oligosaccharide 2′-fucosyllactose modulates CD14 expression in human enterocytes, thereby attenuating LPS-induced inflammation

modulates CD14 expression in human enterocytes, thereby attenuating LPS-induced inflammation