Human Milk Oligosaccharides Inhibit Candida albicans Invasion of Human Premature Intestinal Epithelial Cells

Probiotics in the New Era of Human Milk Oligosaccharides (HMOs): HMO Utilization and Beneficial Effects of Bifidobacterium longum subsp. infantis M-63 on Infant Health

A healthy gut microbiome is crucial for the immune system and overall development of infants. Bifidobacterium has been known to be a predominant species in the infant gut; however, an emerging concern is the apparent loss of this genus, in particular, Bifidobacterium longum subsp. infantis (B. infantis) in the gut microbiome of infants in industrialized nations, underscoring the importance of restoring this beneficial bacterium. With the growing understanding of the gut microbiome, probiotics, especially infant-type human-residential bifidobacteria (HRB) strains like B. infantis, are gaining prominence for their unique ability to utilize HMOs and positively influence infant health. This article delves into the physiology of a probiotic strain, B. infantis M-63, its symbiotic relationship with HMOs, and its potential in improving gastrointestinal and allergic conditions in infants and children. Moreover, this article critically assesses the role of HMOs and the emerging trend of supplementing infant formulas with the prebiotic HMOs, which serve as fuel for beneficial gut bacteria, thereby emulating the protective effects of breastfeeding. The review highlights the potential of combining B. infantis M-63 with HMOs as a feasible strategy to improve health outcomes in infants and children, acknowledging the complexities and requirements for further research in this area.

Label-Free Liquid Chromatography-Mass Spectrometry Quantitation of Relative N- and O-Glycan Concentrations in Human Milk in Japan

Human milk is abundant in carbohydrates and includes human milk oligosaccharides (HMOs) and N/O-glycans conjugated to proteins. HMO compositions and concentrations vary in individuals according to the maternal secretor status based on the fucosyltransferase 2 genotype; however, the profile of N/O-glycans remains uninvestigated because of the analytical complexity. Herein, we applied a label-free chromatography-mass spectrometry (LC-MS) technique to elucidate the variation in the composition and concentration of N/O-glycans in human milk. We used label-free LC-MS to relatively quantify 16 N-glycans and 12 O-glycans in 200 samples of Japanese human milk (1-2 months postpartum) and applied high performance anion exchange chromatography with pulsed amperometric detection to absolutely quantify the concentrations of 11 representative HMOs. Cluster analysis of the quantitative data revealed that O-glycans and several HMOs were classified according to the presence or absence of fucose linked to galactose while N-glycans were classified into a different group from O-glycans and HMOs. O-glycans and HMOs with fucose linked to galactose were more abundant in human milk from secretor mothers than from nonsecretor mothers. Thus, secretor status influenced the composition and concentration of HMOs and O-glycans but not those of N-glycans in human milk.

Age-dependent associations of human milk oligosaccharides with body size and composition up to 4 years of age

BACKGROUND

Human milk oligosaccharides (HMOs) are major components of human milk that may mediate its beneficial effects on infant growth.

OBJECTIVES

To investigate relationships between HMO concentrations in milk at 6 wk postpartum and anthropometry to 4 y of age in human milk-fed infants.

METHODS

Milk samples were collected from 292 mothers at 6 wk (median 6.0 wk; range 3.3, 11.1] postpartum in a longitudinal, population-derived cohort. Of the infants, 171 were exclusively human milk-fed to 3 mo of age and 127 to 6 mo. Concentrations of 19 HMOs were quantified using high-performance liquid chromatography. Maternal secretor status (n = 221 secretors) was determined from 2'-fucosyllactose (2'FL) concentration. We calculated z-scores for child weight, length, head circumference, summed triceps and subscapular skinfold thicknesses, and weight-for-length at 6 wk, 6 mo, 12 mo, and 4 y. We investigated associations of secretor status and each HMO measure with change from birth for each z-score using linear mixed-effects models.

RESULTS

Maternal secretor status was not associated with anthropometric z-scores up to 4 y of age. Several HMOs were associated with z-scores at 6 wk and 6 mo, predominantly within secretor status subgroups. Higher levels of 2'FL were associated with greater weight [β = 0.91 increase in z-score per SD increase log-2'FL, 95% CI (0.17, 1.65)] and length [β = 1.22, (0.25, 2.20)] in children born to secretor mothers, but not body composition measures. Higher lacto-N-tetraose was associated with greater weight [β = 0.22, (0.02, 0.41)] and length (β = 0.30, (0.07, 0.53)] among children born to nonsecretor mothers. Several HMOs were associated with anthropometric measures at 12 mo and 4 y of age.

CONCLUSIONS

Milk HMO composition at 6 wk postpartum is associated with several anthropometry measures up to 6 mo of age in a potential secretor status-specific manner, with largely different HMOs associating with anthropometry from 12 mo to 4 y of age.

The Nonbacterial Microbiome: Fungal and Viral Contributions to the Preterm Infant Gut in Health and Disease

The intestinal microbiome is frequently implicated in necrotizing enterocolitis (NEC) pathogenesis. While no particular organism has been associated with NEC development, a general reduction in bacterial diversity and increase in pathobiont abundance has been noted preceding disease onset. However, nearly all evaluations of the preterm infant microbiome focus exclusively on the bacterial constituents, completely ignoring any fungi, protozoa, archaea, and viruses present. The abundance, diversity, and function of these nonbacterial microbes within the preterm intestinal ecosystem are largely unknown. Here, we review findings on the role of fungi and viruses, including bacteriophages, in preterm intestinal development and neonatal intestinal inflammation, with potential roles in NEC pathogenesis yet to be determined. In addition, we highlight the importance of host and environmental influences, interkingdom interactions, and the role of human milk in shaping fungal and viral abundance, diversity, and function within the preterm intestinal ecosystem.

Glycopolymers against pathogen infection

Pathogens including viruses, bacteria, fungi, and parasites continue to shape our lives in profound ways every day. As we have learned to live in parallel with pathogens, we have gained a better understanding of the rules of engagement for how they bind, adhere, and invade host cells. One such mechanism involves the exploitation of host cell surface glycans for attachment/adhesion, one of the first steps of infection. This knowledge has led to the development of glycan-based diagnostics and therapeutics for the treatment and prevention of infection. One class of compounds that has become increasingly important are the glycopolymers. Glycopolymers are macromolecules composed of a synthetic scaffold presenting carbohydrates as side chain motifs. Glycopolymers are particularly attractive because their properties can be tuned by careful choice of the scaffold, carbohydrate/glycan, and overall presentation. In this review, we highlight studies over the past ten years that have examined the role of glycopolymers in pathogen adhesion and host cell infection, biofilm formation and removal, and drug delivery with the aim of examining the direct effects of these macromolecules on pathogen engagement. In addition, we also examine the role of glycopolymers as diagnostics for the detection and monitoring of pathogens.

Shaping infant development from the inside out: Bioactive factors in human milk

Human breast milk is the optimal nutrition for all infants and is comprised of many bioactive and immunomodulatory components. The components in human milk, such as probiotics, human milk oligosaccharides (HMOs), extracellular vesicles, peptides, immunoglobulins, growth factors, cytokines, and vitamins, play a critical role in guiding neonatal development beyond somatic growth. In this review, we will describe the bioactive factors in human milk and discuss how these factors shape neonatal immunity, the intestinal microbiome, intestinal development, and more from the inside out.

Early life inter-kingdom interactions shape the immunological environment of the airways

BACKGROUND

There is increasing evidence that the airway microbiome plays a key role in the establishment of respiratory health by interacting with the developing immune system early in life. While it has become clear that bacteria are involved in this process, there is a knowledge gap concerning the role of fungi. Moreover, the inter-kingdom interactions that influence immune development remain unknown. In this prospective exploratory human study, we aimed to determine early post-natal microbial and immunological features of the upper airways in 121 healthy newborns.

RESULTS

We found that the oropharynx and nasal cavity represent distinct ecological niches for bacteria and fungi. Breastfeeding correlated with changes in microbiota composition of oropharyngeal samples with the greatest impact upon the relative abundance of Streptococcus species and Candida. Host transcriptome profiling revealed that genes with the highest expression variation were immunological in nature. Multi-omics factor analysis of host and microbial data revealed unique co-variation patterns.

CONCLUSION

These data provide evidence of a diverse multi-kingdom microbiota linked with local immunological characteristics in the first week of life that could represent distinct trajectories for future respiratory health.

TRIAL REGISTRATION

NHS Health Research Authority, IRAS ID 199053. Registered 5 Oct 2016. https://www.hra.nhs.uk/planning-and-improving-research/application-summaries/research-summaries/breathing-together/ Video abstract.

Glycosyltransferase from Bacteroides gallinaceum Is a Novel α-1,3-Fucosyltransferase that Can Be Used for 3-Fucosyllactose Production In Vivo by Metabolically Engineered Escherichia coli

As one of the attractive fucosylated human milk oligosaccharides, the biological production of 3-fucosyllactose (3-FL) has received great attention, as it exhibits many excellent physiological functions for infants. In this work, a novel 3-FL-producing α-1,3-fucosyltransferase (α1,3-FucT) named FutM2 from Bacteroides gallinaceum was first selected from nine potential candidates in the NCBI database. Then, a highly 3-FL-producing engineered Escherichia coli strain was constructed by modular pathway enhancement including the GDL-l-fucose precursor supply by overexpressing manC, manB, gmd, and wcaG (CBGW), and the 3-FL synthesis pathway by introducing B. gallinaceum FutM2. Finally, a titer of 20.3 g L^-1 and productivity of 0.40 g L^-1 h^-1 of 3-FL were achieved in the 3-L bioreactor by engineered E. coli (ΔlacZΔwcaJ) harboring pCDF-CBGW and pET-futM2. Our study provided a novel α1,3-FucT from B. gallinaceum that could be used for 3-FL production, presenting an efficient microbial cell factory platform to de novo synthesize 3-FL from glycerol.

Understanding the pathways leading to gut dysbiosis and enteric environmental dysfunction in infants: the influence of maternal dysbiosis and other microbiota determinants during early life

Maternal environmental enteric dysfunction (EED) encompasses undernutrition with an inflammatory gut profile, a variable degree of dysbiosis and increased translocation of pathogens in the gut mucosa. Even though recent research findings have shed light on the pathological pathways underlying the establishment of the infant gut dysbiosis, evidence on how maternal EED influences the development of gut dysbiosis and EED in the offspring remains elusive. This review summarizes the current knowledge on the effect of maternal dysbiosis and EED on infant health, and explores recent progress in unraveling the mechanisms of acquisition of a dysbiotic gut microbiota in the offspring. In Western communities, maternal inoculum, delivery mode, perinatal antibiotics, feeding practices, and infections are the major drivers of the infant gut microbiota during the first two years of life. In other latitudes, the infectious burden and maternal malnutrition might introduce further risk factors for infant gut dysbiosis. Novel tools, such as transcriptomics and metabolomics, have become indispensable to analyze the metabolic environment of the infant in utero and post-partum. Human-milk oligosaccharides have essential prebiotic, antimicrobial, and anti-biofilm properties that might offer additional therapeutic opportunities.

Recent understanding of human milk oligosaccharides in establishing infant gut microbiome and roles in immune system

Human milk oligosaccharides (HMOs) are complex sugars with distinctive structural diversity present in breast milk. HMOs have various functional roles to play in infant development starting from establishing the gut microbiome and immune system to take it up to the mature phase. It has been a major energy source for human gut microbes that confer positive benefits on infant health by directly interacting through intestinal cells and generating short-chain fatty acids. It has recently become evident that each species of Bifidobacterium and other genera which are resident of the infant gut employ distinct molecular mechanisms to capture and digest diverse structural HMOs to avoid competition among themselves and successfully maintain gut homeostasis. HMOs also directly modulate gut immune responses and can decoy receptors of pathogenic bacteria and viruses, inhibiting their binding on intestinal cells, thus preventing the emergence of a disease. This review provides a critical understanding of how different gut bacteria capture and utilize selective sugars from the HMO pool and how different structural HMOs protect infants from infectious diseases.

The relationship between human milk, a functional nutrient, and microbiota

The intestinal microbiota begins to take shape in the mother's womb, changes depending on many factors. It is known that the intestinal microbiota has an important role in the maturation of the immune system, also in the prevention of diseases that occur in newborn, childhood, adulthood. Nutrition is the main factor on the development of microbiota in infants after birth. The microbiota compositions of breastfed infants are different from formula-fed infants. Breast milk oligosaccharides play an important role in the development of infants' microbiota. The higher number of Bifidobacterium species and lower α and β diversity in breastfed infants are considered protective. A dysbiosis occurring in the microbiota can cause adverse effects on health. Human milk oligosaccharides also have protective effects on the microbiota. These protective effects are to promote the growth of intestinal microbiota, prevent the adhesion of viruses to the colon, promote the growth of Bifidobacterium with its prebiotic effect. Short-chain fatty acids resulting from their digestion, also have protective effects. Another component that shapes the gut microbiota is HM glycoproteins. The aim of this study is to examine the effect of breast milk on the development of microbiota, to present the results by scanning the literature.

Metabolic engineering strategies of de novo pathway for enhancing 2'-fucosyllactose synthesis in Escherichia coli

2′‐Fucosyllactose (2′‐FL), one of the most abundant human milk oligosaccharides (HMOs), is used as a promising infant formula ingredient owing to its multiple health benefits for newborns. However, limited availability and high‐cost preparation have restricted its extensive use and intensive research on its potential functions. In this work, a powerful Escherichia coli cell factory was developed to ulteriorly increase 2′‐FL production. Initially, a modular pathway engineering was strengthened to balance the synthesis pathway through different plasmid combinations with a resulting maximum 2′‐FL titre of 1.45 g l⁻¹. To further facilitate the metabolic flux from GDP‐l‐fucose towards 2′‐FL, the CRISPR‐Cas9 system was utilized to inactivate the genes including lacZ and wcaJ, increasing the titre by 6.59‐fold. Notably, the co‐introduction of NADPH and GTP regeneration pathways was confirmed to be more conducive to 2′‐FL formation, achieving a 2′‐FL titre of 2.24 g l⁻¹. Moreover, comparisons of various exogenous α1,2‐fucosyltransferase candidates revealed that futC from Helicobacter pylori generated the highest titre of 2′‐FL. Finally, the viability of scaled‐up production of 2′‐FL was evidenced in a 3 l bioreactor with a maximum titre of 22.3 g l⁻¹ 2′‐FL and a yield of 0.53 mole 2′‐FL mole⁻¹ lactose.

Comparison of Different Labeling Techniques for the LC-MS Profiling of Human Milk Oligosaccharides

Human milk oligosaccharides (HMOs) exhibit various biological activities for infants, such as serving as prebiotics, blocking pathogens, and aiding in brain development. HMOs are a complex mixture of hetero-oligosaccharides that are generally highly branched, containing multiple structural isomers and no intrinsic chromophores, presenting a challenge to both their resolution and quantitative detection. While liquid chromatography-mass spectrometry (LC-MS) has become the primary strategy for analysis of various compounds, the very polar and chromophore-free properties of native glycans hinder their separation in LC and ionization in MS. Various labeling approaches have been developed to achieve separation of glycans with higher resolution and greater sensitivity of detection. Here, we compared five commonly used labeling techniques [by 2-aminobenzamide, 2-aminopyridine, 2-aminobenzoic acid (2-AA), 2,6-diaminopyridine, and 1-phenyl-3-methyl-5-pyrazolone] for analyzing HMOs specifically under hydrophilic-interaction chromatography-mass spectrometry (HILIC-MS) conditions. The 2-AA labeling showed the most consistent deprotonated molecular ions, the enhanced sensitivity with the least structural selectivity, and the sequencing-informative tandem MS fragmentation spectra for the widest range of HMOs; therefore, this labeling technique was selected for further optimization under the porous graphitized carbon chromatography-mass spectrometry (PGC-MS) conditions. The combination strategy of 2-AA labeling and PGC-MS techniques provided online decontamination (removal of excess 2-AA, salts, and lactose) and resolute detection of many HMOs, enabling us to characterize the profiles of complicated HMO mixtures comprehensively in a simple protocol.

Composition and Associations of the Infant Gut Fungal Microbiota with Environmental Factors and Childhood Allergic Outcomes

Although often neglected in gut microbiota studies, recent evidence suggests that imbalanced, or dysbiotic, gut mycobiota (fungal microbiota) communities in infancy coassociate with states of bacterial dysbiosis linked to inflammatory diseases such as asthma. In the present study, we (i) characterized the infant gut mycobiota at 3 months and 1 year of age in 343 infants from the CHILD Cohort Study, (ii) defined associations among gut mycobiota community composition and environmental factors for the development of inhalant allergic sensitization (atopy) at age 5 years, and (iii) built a predictive model for inhalant atopy status at age 5 years using these data. We show that in Canadian infants, fungal communities shift dramatically in composition over the first year of life. Early-life environmental factors known to affect gut bacterial communities were also associated with differences in gut fungal community alpha diversity, beta diversity, and/or the relative abundance of specific fungal taxa. Moreover, these metrics differed among healthy infants and those who developed inhalant allergic sensitization (atopy) by age 5 years. Using a rationally selected set of early-life environmental factors in combination with fungal community composition at 1 year of age, we developed a machine learning logistic regression model that predicted inhalant atopy status at 5 years of age with 81% accuracy. Together, these data suggest an important role for the infant gut mycobiota in early-life immune development and indicate that early-life behavioral or therapeutic interventions have the potential to modify infant gut fungal communities, with implications for an infant's long-term health. IMPORTANCE Recent evidence suggests an immunomodulatory role for commensal fungi (mycobiota) in the gut, yet little is known about the composition and dynamics of early-life gut fungal communities. In this work, we show for the first time that the composition of the gut mycobiota of Canadian infants changes dramatically over the course of the first year of life, is associated with environmental factors such as geographical location, diet, and season of birth, and can be used in conjunction with knowledge of a small number of key early-life factors to predict inhalant atopy status at age 5 years. Our study highlights the importance of considering fungal communities as indicators or inciters of immune dysfunction preceding the onset of allergic disease and can serve as a benchmark for future studies aiming to examine infant gut fungal communities across birth cohorts.

Gold standard for nutrition: a review of human milk oligosaccharide and its effects on infant gut microbiota

Human milk is the gold standard for nutrition of infant growth, whose nutritional value is mainly attributed to human milk oligosaccharides (HMOs). HMOs, the third most abundant component of human milk after lactose and lipids, are complex sugars with unique structural diversity which are indigestible by the infant. Acting as prebiotics, multiple beneficial functions of HMO are believed to be exerted through interactions with the gut microbiota either directly or indirectly, such as supporting beneficial bacteria growth, anti-pathogenic effects, and modulation of intestinal epithelial cell response. Recent studies have highlighted that HMOs can boost infants health and reduce disease risk, revealing potential of HMOs in food additive and therapeutics. The present paper discusses recent research in respect to the impact of HMO on the infant gut microbiome, with emphasis on the molecular basis of mechanism underlying beneficial effects of HMOs.

Human Milk Microbiota and Oligosaccharides: A Glimpse into Benefits, Diversity, and Correlations

Human milk represents a cornerstone for growth and development of infants, with extensive array of benefits. In addition to exceptionally nutritive and bioactive components, human milk encompasses a complex community of signature bacteria that helps establish infant gut microbiota, contributes to maturation of infant immune system, and competitively interferes with pathogens. Among bioactive constituents of milk, human milk oligosaccharides (HMOs) are particularly significant. These are non-digestible carbohydrates forming the third largest solid component in human milk. Valuable effects of HMOs include shaping intestinal microbiota, imparting antimicrobial effects, developing intestinal barrier, and modulating immune response. Moreover, recent investigations suggest correlations between HMOs and milk microbiota, with complex links possibly existing with environmental factors, genetics, geographical location, and other factors. In this review, and from a physiological and health implications perspective, milk benefits for newborns and mothers are highlighted. From a microbiological perspective, a focused insight into milk microbiota, including origins, diversity, benefits, and effect of maternal diet is presented. From a metabolic perspective, biochemical, physiological, and genetic significance of HMOs, and their probable relations to milk microbiota, are addressed. Ongoing research into mechanistic processes through which the rich biological assets of milk promote development, shaping of microbiota, and immunity is tackled.

Home, sweet home: how mucus accommodates our microbiota

As a natural environment for human-microbiota interactions, healthy mucus houses a remarkably stable and diverse microbial community. Maintaining this microbiota is essential to human health, both to support the commensal bacteria that perform a wide array of beneficial functions and to prevent the outgrowth of pathogens. However, how the host selects and maintains a specialized microbiota remains largely unknown. In this viewpoint, we propose several strategies by which mucus may regulate the composition and function of the human microbiota and discuss how compromised mucus barriers in disease can give rise to microbial dysbiosis.

In Love with Shaping You-Influential Factors on the Breast Milk Content of Human Milk Oligosaccharides and Their Decisive Roles for Neonatal Development

Human milk oligosaccharides (HMOs) are structurally versatile sugar molecules constituting the third major group of soluble components in human breast milk. Based on the disaccharide lactose, the mammary glands of future and lactating mothers produce a few hundreds of different HMOs implicating that their overall anabolism utilizes rather high amounts of energy. At first sight, it therefore seems contradictory that these sugars are indigestible for infants raising the question of why such an energy-intensive molecular class evolved. However, in-depth analysis of their molecular modes of action reveals that Mother Nature created HMOs for neonatal development, protection and promotion of health. This is not solely facilitated by HMOs in their indigestible form but also by catabolites that are generated by microbial metabolism in the neonatal gut additionally qualifying HMOs as natural prebiotics. This narrative review elucidates factors influencing the HMO composition as well as physiological roles of HMOs on their way through the infant body and within the gut, where a major portion of HMOs faces microbial catabolism. Concurrently, this work summarizes in vitro, preclinical and observational as well as interventional clinical studies that analyzed potential health effects that have been demonstrated by or were related to either human milk-derived or synthetic HMOs or HMO fractions.

Human milk oligosaccharides: Shaping the infant gut microbiota and supporting health

Human milk oligosaccharides (HMO) are complex sugars which are found in breast milk at significant concentrations and with unique structural diversity. These sugars are the fourth most abundant component of human milk after water, lipids, and lactose and yet provide no direct nutritional value to the infant. Recent research has highlighted that HMOs have various functional roles to play in infant development. These sugars act as prebiotics by promoting growth of beneficial intestinal bacteria thereby generating short-chain fatty acids which are critical for gut health. HMOs also directly modulate host-epithelial immune responses and can selectively reduce binding of pathogenic bacteria and viruses to the gut epithelium preventing the emergence of a disease. This review covers current knowledge related to the functional biology of HMOs and their associated impact on infant gut health.

Human Milk Oligosaccharides Mediate the Crosstalk Between Intestinal Epithelial Caco-2 Cells and Lactobacillus PlantarumWCFS1in an In Vitro Model with Intestinal Peristaltic Shear Force

BACKGROUND

The intestinal epithelial cells, food molecules, and gut microbiota are continuously exposed to intestinal peristaltic shear force. Shear force may impact the crosstalk of human milk oligosaccharides (hMOs) with commensal bacteria and intestinal epithelial cells.

OBJECTIVES

We investigated how hMOs combined with intestinal peristaltic shear force impact intestinal epithelial cells and crosstalk with a commensal bacterium.

METHODS

We applied the Ibidi system to mimic intestinal peristaltic shear force. Caco-2 cells were exposed to a shear force (5 dynes/cm2) for 3 d, and then stimulated with the hMOs, 2'-fucosyllactose (2'-FL), 3-FL, and lacto-N-triose II (LNT2). In separate experiments, Lactobacillus plantarumWCFS1 adhesion to Caco-2 cells was studied with the same hMOs and shear force. Effects were tested on gene expression of glycocalyx-related molecules (glypican 1 [GPC1], hyaluronan synthase 1 [HAS1], HAS2, HAS3, exostosin glycosyltransferase 1 [EXT1], EXT2), defensin β-1 (DEFB1), and tight junction (tight junction protein 1 [TJP1], claudin 3 [CLDN3]) in Caco-2 cells. Protein expression of tight junctions was also quantified.

RESULTS

Shear force dramatically decreased gene expression of the main enzymes for making glycosaminoglycan side chains (HAS3 by 43.3% and EXT1 by 68.7%) (P <0.01), but did not affect GPC1 which is the gene responsible for the synthesis of glypican 1 which is a major protein backbone of glycocalyx. Expression of DEFB1, TJP1, and CLDN3 genes was decreased 60.0-94.9% by shear force (P <0.001). The presence of L. plantarumWCFS1 increased GPC1, HAS2, HAS3, and ZO-1 expression by 1.78- to 3.34-fold (P <0.05). Under shear force, all hMOs significantly stimulated DEFB1 and ZO-1, whereas only 3-FL and LNT2 enhanced L. plantarumWCFS1 adhesion by 1.85- to 1.90-fold (P <0.01).

CONCLUSIONS

3-FL and LNT2 support the crosstalk between the commensal bacterium L. plantarumWCFS1 and Caco-2 intestinal epithelial cells, and shear force can increase the modulating effects of hMOs.

Candida albicans in celiac disease: A wolf in sheep's clothing

Candida albicans is a commensal fungus with a potential pathogenicity and celiac disease is an autoimmune condition. Both share multiple pathophysiological junctions, including serological markers against cell-wall proteins of Candida, anti-gliadin antibodies are positive in both entities, gluten and a candidal virulence factor share sequence similarity and the autoantigen of celiac disease, the tissue transglutaminase, is pivotal in Candida albicans commensalism and hostile behavior and its covalently cross linked products are stable and resistant to breakdown in the two entities. Those autoimmune/infectious cross roads are the basis for the hypothesis that Candida albicans is an additional environmental factor for celiac disease autoimmunogenesis.

Development of fluorescent Escherichia coli for a whole-cell sensor of 2'-fucosyllactose

2′-Fucosyllactose (2′-FL), a major component of fucosylated human milk oligosaccharides, is beneficial to human health in various ways like prebiotic effect, protection from pathogens, anti-inflammatory activity and reduction of the risk of neurodegeneration. Here, a whole-cell fluorescence biosensor for 2′-FL was developed. Escherichia coli (E. coli) was engineered to catalyse the cleavage of 2′-FL into l-fucose and lactose by constitutively expressing α-l-fucosidase. Escherichia coli ∆L YA, in which lacZ is deleted and lacY is retained, was employed to disable lactose consumption. E. coli ∆L YA constitutively co-expressing α-l-fucosidase and a red fluorescence protein (RFP) exhibited increased fluorescence intensity in media containing 2′-FL. However, the presence of 50 g/L lactose reduced the RFP intensity due to lactose-induced cytotoxicity. Preadaptation of bacterial strains to fucose alleviated growth hindrance by lactose and partially recovered the fluorescence intensity. The fluorescence intensity of the cell was linearly proportional to 1–5 g/L 2′-FL. The whole-cell sensor will be versatile in developing a 2′-FL detection system.

Like mother, like microbe: human milk oligosaccharide mediated microbiome symbiosis

Starting shortly after parturition, and continuing throughout our lifetime, the gut microbiota coevolves with our metabolic and neurological programming. This symbiosis is regulated by a complex interplay between the host and environmental factors, including diet and lifestyle. Not surprisingly, the development of this microbial community is of critical importance to health and wellness. In this targeted review, we examine the gut microbiome from birth to 2 years of age to characterize the role human milk oligosaccharides play in early formation of microbial flora.

Human milk fungi: environmental determinants and inter-kingdom associations with milk bacteria in the CHILD Cohort Study

Background

Fungi constitute an important yet frequently neglected component of the human microbiota with a possible role in health and disease. Fungi and bacteria colonise the infant gastrointestinal tract in parallel, yet most infant microbiome studies have ignored fungi. Milk is a source of diverse and viable bacteria, but few studies have assessed the diversity of fungi in human milk.

Results

Here we profiled mycobiota in milk from 271 mothers in the CHILD birth cohort and detected fungi in 58 (21.4%). Samples containing detectable fungi were dominated by Candida, Alternaria, and Rhodotorula, and had lower concentrations of two human milk oligosaccharides (disialyllacto-N-tetraose and lacto-N-hexaose). The presence of milk fungi was associated with multiple outdoor environmental features (city, population density, and season), maternal atopy, and early-life antibiotic exposure. In addition, despite a strong positive correlation between bacterial and fungal richness, there was a co-exclusion pattern between the most abundant fungus (Candida) and most of the core bacterial genera.

Conclusion

We profiled human milk mycobiota in a well-characterised cohort of mother-infant dyads and provide evidence of possible host-environment interactions in fungal inoculation. Further research is required to establish the role of breastfeeding in delivering fungi to the developing infant, and to assess the health impact of the milk microbiota in its entirety, including both bacterial and fungal components.

T Cells in Preterm Infants and the Influence of Milk Diet

Preterm infants born before 32 weeks gestational age (GA) have high rates of late onset sepsis (LOS) and necrotizing enterocolitis (NEC) despite recent improvements in infection control and nutrition. Breast milk has a clear protective effect against both these outcomes likely due to multiple mechanisms which are not fully understood but may involve effects on both the infant's immune system and the developing gut microbiota. Congregating at the interface between the mucosal barrier and the microbiota, innate and adaptive T lymphocytes (T cells) participate in this interaction but few studies have explored their development after preterm delivery. We conducted a literature review of T cell development that focuses on fetal development, postnatal maturation and the influence of milk diet. The majority of circulating T cells in the preterm infant display a naïve phenotype but are still able to initiate functional responses similar to those seen in term infants. T cells from preterm infants display a skew toward a T-helper 2(Th2) phenotype and have an increased population of regulatory cells (Tregs). There are significant gaps in knowledge in this area, particularly in regards to innate-like T cells, but work is emerging: transcriptomics and mass cytometry are currently being used to map out T cell development, whilst microbiomic approaches may help improve understanding of events at mucosal surfaces. A rapid rise in organoid models will allow robust exploration of host-microbe interactions and may support the development of interventions that modulate T-cell responses for improved infant health.

Human Milk Oligosaccharides Activate Epidermal Growth Factor Receptor and Protect Against Hypoxia-Induced Injuries in the Mouse Intestinal Epithelium and Caco2 Cells

BACKGROUND

Hypoxia-induced intestinal barrier injuries lead to necrotizing enterocolitis (NEC). Although NEC in preterm neonates is preventable by human milk oligosaccharides (HMOs), the underlying mechanism remains unknown.

OBJECTIVE

To reveal the role and mechanism of HMOs in protecting against hypoxia-induced injuries in intestinal epithelium of neonatal mice and cultured Caco2 cells.

METHODS

NEC was induced by hypoxia and cold stress. Seventy C57BL/C pups (7-d-old) were divided into 5 groups and fed maternal breast milk (BM), formula alone (FF), or the formula added with HMOs at 5 (LHMO), 10 (MHMO), or 20 mg/mL (HHMO) for 3 d. Ileal hypoxia inducible factor 1α (HIF1α) and cleaved Caspase 3 were determined, along with staining for Ki-67 protein to labeled proliferative cells. In vitro, adherent Caco2 cells (undifferentiated, passage 14) were treated with HMOs, galacto-oligosaccharides, fructo-oligosaccharides, or mixed oligosaccharides at 10 mg/mL for 1 d exposed to 1% O2. Cell proliferation and apoptosis, along with phosphorylated epidermal growth factor receptor (P-EGFR) and 38KD MAPK (P-P38), were assayed in differentiated or undifferentiated Caco2 cells.

RESULTS

Compared with the FF-fed mice, those fed MHMO and HHMO had 52% lower (P < 0.05) NEC scores, 60-80% greater (P < 0.05) KI67-positive cell numbers, and 56-71% decreases (P < 0.05) in ileal HIF1α and cleaved Caspase 3 (56-71%). Compared with those untreated, the HMO-treated Caco2 cells displayed 60% greater (P < 0.05) proliferative activity and 19% lower (P < 0.05) apoptotic cells after the hypoxia exposure. The HMO treatment led to 58% or 10-fold increases (P < 0.05) of P-EGFR and 48-89% decreases (P < 0.05) of P-P38 in either differentiated or undifferentiated Caco2 cells compared with the controls.

CONCLUSION

Supplementing HMOs at 10-20 mg/mL into the formula for neonatal mice or media for Caco2 cells conferred protection against the hypoxia-induced injuries. The protection in the Caco2 cells was associated with an activation of EGFR.

The Determinants of the Human Milk Metabolome and Its Role in Infant Health

Human milk is needed for optimal growth as it satisfies both the nutritional and biological needs of an infant. The established relationship between breastfeeding and an infant’s health is attributable to the nutritional and non-nutritional, functional components of human milk including metabolites such as the lipids, amino acids, biogenic amines and carbohydrates. These components have diverse roles, including protecting the infant against infections and guiding the development of the infant’s immature immune system. In this review, we provide an in-depth and updated insight into the immune modulatory and anti-infective role of human milk metabolites and their effects on infant health and development. We also review the literature on potential determinants of the human milk metabolome, including maternal infectious diseases such as human immunodeficiency virus and mastitis.

Microbiota-dependent and -independent effects of dietary fibre on human health

Dietary fibre, such as indigestible oligosaccharides and polysaccharides, occurs in many foods and has gained considerable importance related to its beneficial effects on host health and specific diseases. Dietary fibre is neither digested nor absorbed in the small intestine and modulates the composition of the gut microbiota. New evidence indicates that dietary fibre also interacts directly with the epithelium and immune cells throughout the gastrointestinal tract by microbiota-independent effects. This review focuses on how dietary fibre improves human health and the reported health benefits that are connected to molecular pathways, in (a) a microbiota-independent manner, via interaction with specific surface receptors on epithelial and immune cells regulating intestinal barrier and immune function, and (b) a microbiota-dependent manner via maintaining intestinal homeostasis by promoting beneficial microbes, including Bifidobacteria and Lactobacilli, limiting the growth, adhesion, and cytotoxicity of pathogenic microbes, as well as stimulating fibre-derived microbial short-chain fatty acid production. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

Complete Genome Sequence of Kosakonia sp. Strain CCTCC M2018092, a Fucose-Rich Exopolysaccharide Producer

Kosakonia sp. strain CCTCC M2018092 is a fucose-rich exopolysaccharide producer that was isolated from spring water in Chongqing, Southwest China. In this study, the whole-genome sequence and genetic characteristics of this strain were elucidated. This genome contained 4,789,478 bp, with a G+C content of 56.08% (excluding the plasmid). The genome information in this study will facilitate understanding of the mechanism of high yield of fucose-rich exopolysaccharide produced by Kosakonia sp.

Kosakonia sp. strain CCTCC M2018092 is a fucose-rich exopolysaccharide producer that was isolated from spring water in Chongqing, Southwest China. In this study, the whole-genome sequence and genetic characteristics of this strain were elucidated. This genome contained 4,789,478 bp, with a G+C content of 56.08% (excluding the plasmid). The genome information in this study will facilitate understanding of the mechanism of high yield of fucose-rich exopolysaccharide produced by Kosakonia sp. CCTCC M2018092.

Creating an in vivo bifunctional gene expression circuit through an aptamer-based regulatory mechanism for dynamic metabolic engineering in Bacillus subtilis

Aptamer-based regulatory biosensors can dynamically regulate the expression of target genes in response to ligands and could be used in dynamic metabolic engineering for pathway optimization. However, the existing aptamer-ligand biosensors can only function with non-complementary DNA elements that cannot replicate in growing cells. Here, we construct an aptamer-based synthetic regulatory circuit that can dynamically upregulate and downregulate the expression of target genes in response to the ligand thrombin at transcriptional and translational levels, respectively, and further used this system to dynamically engineer the synthesis of 2'-fucosyllactose (2'-FL) in Bacillus subtilis. First, we demonstrated the binding of ligand molecule thrombin with the aptamer can induce the unwinding of fully complementary double-stranded DNA. Based on this finding, we constructed a bifunctional gene expression regulatory circuit using ligand thrombin-bound aptamers. The expression of the reporter gene ranged from 0.084- to 48.1-fold. Finally, by using the bifunctional regulatory circuit, we dynamically upregulated the expression of key genes fkp and futC and downregulated the expression of gene purR, resulting in the significant increase of 2'-FL titer from 24.7 to 674 mg/L. Compared with the other pathway-specific dynamic engineering systems, here the constructed aptamer-based regulatory circuit is independent of pathways, and can be generally used to fine-tune gene expression in other microbes.

Infectious Agents in Bovine Red Meat and Milk and Their Potential Role in Cancer and Other Chronic Diseases

Red meat and dairy products have frequently been suggested to represent risk factors for certain cancers, chronic neurodegenerative diseases, and autoimmune and cardiovascular disorders. This review summarizes the evidence and investigates the possible involvement of infectious factors in these diseases. The isolation of small circular single-stranded DNA molecules from serum and dairy products of Eurasian Aurochs (Bos taurus)-derived cattle, obviously persisting as episomes in infected cells, provides the basis for further investigations. Gene expression of these agents in human cells has been demonstrated, and frequent infection of humans is implicated by the detection of antibodies in a high percentage of healthy individuals. Epidemiological observations suggest their relationship to the development multiple sclerosis, to heterophile antibodies, and to N-glycolylneuraminic acid (Neu5Gc) containing cell surface receptors.

Biochemical characterization of Helicobacter pylori α1-3-fucosyltransferase and its application in the synthesis of fucosylated human milk oligosaccharides

Fucosylated human milk oligosaccharides (HMOs) have important biological functions. Enzymatic synthesis of such compounds requires robust fucosyltransferases. A C-terminal 66-amino acid truncated version of Helicobacter pylori α1-3-fucosyltransferase (Hp3FT) is a good candidate. Hp3FT was biochemically characterized to identify optimal conditions for enzymatic synthesis of fucosides. While N-acetyllactosamine (LacNAc) and lactose were both suitable acceptors, the former is preferred. At a low guanosine 5'-diphospho-β-L-fucose (GDP-Fuc) to acceptor ratio, Hp3FT selectively fucosylated LacNAc. Based on these enzymatic characteristics, diverse fucosylated HMOs, including 3-fucosyllactose (3-FL), lacto-N-fucopentaose (LNFP) III, lacto-N-neofucopentaose (LNnFP) V, lacto-N-neodifucohexaose (LNnDFH) II, difuco- and trifuco-para-lacto-N-neohexaose (DF-paraLNnH and TF-para-LNnH), were synthesized enzymatically by varying the ratio of the donor and acceptor as well as controlling the order of multiple glycosyltransferase-catalyzed reactions.

Development of the Pediatric Gut Microbiome: Impact on Health and Disease

The intestinal microbiota are important in human growth and development. Microbial composition may yield insights into the temporal development of microbial communities and vulnerabilities to disorders of microbial ecology such as recurrent Clostridium difficile infection. Discoveries of key microbiome features of carbohydrate and amino acid metabolism are lending new insights into possible therapies or preventative strategies for inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). In this review, we summarize the current understanding of the development of the pediatric gastrointestinal microbiome, the influence of the microbiome on the developing brain through the gut-brain axis, and the impact of dysbiosis on disease development. Dysbiosis is explored in the context of pediatric allergy and asthma, recurrent C. difficile infection, IBD, IBS, and metabolic disorders. The central premise is that the human intestinal microbiome plays a vital role in health and disease, beginning in the prenatal period and extending throughout childhood.

Human Milk Oligosaccharides and Immune System Development

Maternal milk contains compounds that may affect newborn immunity. Among these are a group of oligosaccharides that are synthesized in the mammary gland from lactose; these oligosaccharides have been termed human milk oligosaccharides (HMOs). The amount of HMOs present in human milk is greater than the amount of protein. In fact, HMOs are the third-most abundant solid component in maternal milk after lactose and lipids, and are thus considered to be key components. The importance of HMOs may be explained by their inhibitory effects on the adhesion of microorganisms to the intestinal mucosa, the growth of pathogens through the production of bacteriocins and organic acids, and the expression of genes that are involved in inflammation. This review begins with short descriptions of the basic structures of HMOs and the gut immune system, continues with the beneficial effects of HMOs shown in cell and animal studies, and it ends with the observational and randomized controlled trials carried out in humans to date, with particular emphasis on their effect on immune system development. HMOs seem to protect breastfed infants against microbial infections. The protective effect has been found to be exerted through cell signaling and cell-to-cell recognition events, enrichment of the protective gut microbiota, the modulation of microbial adhesion, and the invasion of the infant intestinal mucosa. In addition, infants fed formula supplemented with selected HMOs exhibit a pattern of inflammatory cytokines closer to that of exclusively breastfed infants. Unfortunately, the positive effects found in preclinical studies have not been substantiated in the few randomized, double-blinded, multicenter, controlled trials that are available, perhaps partly because these studies focus on aspects other than the immune response (e.g., growth, tolerance, and stool microbiota).

Linkage-Specific Detection and Metabolism of Human Milk Oligosaccharides in Escherichia coli

Human milk oligosaccharides (HMOs) are important prebiotic complex carbohydrates with demonstrated beneficial effects on the microbiota of neonates. However, optimization of their biotechnological synthesis is limited by the relatively low throughput of monosaccharide and linkage analysis. To enable high-throughput screening of HMO structures, we constructed a whole-cell biosensor that uses heterologous expression of glycosidases to generate linkage-specific, quantitative fluorescent readout for a range of HMOs at detection limits down to 20 μM in approximately 6 hr. We also demonstrate the use of this system for orthogonal control of growth rate or protein expression of particular strains in mixed populations. This work enables rapid non-chromatographic linkage analysis and lays the groundwork for the application of directed evolution to biosynthesis of complex carbohydrates as well as the prebiotic manipulation of population dynamics in natural and engineered microbial communities.

Systematic Review of the Effect of Enteral Feeding on Gut Microbiota in Preterm Infants

OBJECTIVE

To examine the effect of feeding type on microbial patterns among preterm infants and to identify feeding factors that promote the colonization of beneficial bacteria.

DATA SOURCES

PubMed, Cochrane Database of Systematic Reviews, Scopus, and the Cummulative Index of Nursing and Allied Health Literature were thoroughly searched for articles published between January 2000 and January 2017, using the keywords gut microbiome, gut microbiota, enteral microbiome, enteral microbiota, premature infant, preterm infant, extremely low birth weight infant, ELBW infant, very low birth weight infant, feeding, breast milk, breastfeeding, formula, prebiotic, probiotic, and long chain polyunsaturated fatty acid.

STUDY SELECTION

Primary studies written in English and focused on the association between enteral feeding and gut microbiome patterns of preterm infants were included in the review.

DATA EXTRACTION

We independently reviewed the selected articles and extracted information using predefined data extraction criteria including study design, study participants, type of feeding, type and frequency of biospecimen (e.g., feces, gastric aspirate) collection, microbiological analysis method, and major results.

DATA SYNTHESIS

In 4 of the 18 studies included in the review, researchers described the effects of milk products (mothers' own milk, donor human milk, and formula). In 5 studies, the effects of prebiotics were assessed, and in 9 studies, the effects of probiotics on the gut microbiome were described. Mothers' own breast milk feeding influenced the compositional structure of preterm infants' gut microbial community and increased diversity of gut microbiota compared with donor human milk and formula feeding. The results of the use of prebiotics and probiotics varied among studies; however, the majority of the researchers reported positive bifidogenic effects on the development of beneficial bacteria.

CONCLUSION

Mothers' own milk is considered the best form of nutrition for preterm infants and the gut microbial community. Variation in fatty acid composition across infant feeding types can affect microbial composition. The evidence for supplementation of prebiotics and probiotics to promote the gut microbial community structure is compelling; however, additional research is needed in this area.

Advanced analytical strategies for measuring free bioactive milk sugars: from composition and concentrations to human metabolic response

Our daily food intake provides the nutrients to maintain health. However, in addition to the nutritional values, food can promote health and be beneficial in preventing diseases. Human milk is a unique food source that contains essential nutrients in the right balance and other bioactive factors that make it the ideal food for all healthy term infants. Human milk oligosaccharides (HMOs) play an important role in health, at several levels: acting as prebiotics promoting the growth of beneficial bacterial strains, preventing the growth of pathogenic bacteria in the intestine, and modulating the immune response against bacterial infections. However, despite their biological relevance and the advances made in the analytical field, very few studies have been carried out to better understand HMOs bioactivity mechanisms or to examine human metabolic response to dietary supplementation. This review describes the state-of-the-art of glycomics strategies, recent analytical methods, and future trends for the identification and discovery of bioactive sugars, the known mechanisms of action, and discusses findings of some recent human intervention trials.

The Human Milk Glycome as a Defense Against Infectious Diseases: Rationale, Challenges, and Opportunities

Each year over 3 million people die from infectious diseases with most of these deaths being poor and young children who live in low- and middle-income countries. Infectious diseases emerge for a multitude of reasons. On the social front, reasons include a breakdown of public health standards, international travel, and immigration (for financial, civil, and social reasons). At the molecular level, the modern rise of infectious diseases is tied to the juxtaposition of drug-resistant pathogens and a lack of new antimicrobials. The consequence is the possibility that humankind will return to the preantibiotic era wherein millions of people will perish from what should be trivial illnesses. Given the stakes, it is imperative that the chemistry community take leadership in delivering new antibiotic leads for clinical development. We believe this can happen through innovation in two areas. First is the development of novel chemical scaffolds to treat infections caused by multidrug-resistant pathogens. The second area, which is not exclusive to the first, is the generation of antibiotics that do not cause collateral damage to the host or the host's microbiome. Both can be enabled through advances in chemical synthesis. It is with this general philosophy in mind that we hypothesized human milk oligosaccharides (HMOs) could serve as novel chemical scaffolds for antibacterial development. We provide herein a personal account of our laboratory's progress toward the goal of using HMOs as a defense against infectious diseases.

Immunological Effects of Human Milk Oligosaccharides

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.

The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota

The human gut microbiota is engaged in multiple interactions affecting host health during the host's entire life span. Microbes colonize the neonatal gut immediately following birth. The establishment and interactive development of this early gut microbiota are believed to be (at least partially) driven and modulated by specific compounds present in human milk. It has been shown that certain genomes of infant gut commensals, in particular those of bifidobacterial species, are genetically adapted to utilize specific glycans of this human secretory fluid, thus representing a very intriguing example of host-microbe coevolution, where both partners are believed to benefit. In recent years, various metagenomic studies have tried to dissect the composition and functionality of the infant gut microbiome and to explore the distribution across the different ecological niches of the infant gut biogeography of the corresponding microbial consortia, including those corresponding to bacteria and viruses, in healthy and ill subjects. Such analyses have linked certain features of the microbiota/microbiome, such as reduced diversity or aberrant composition, to intestinal illnesses in infants or disease states that are manifested at later stages of life, including asthma, inflammatory bowel disease, and metabolic disorders. Thus, a growing number of studies have reported on how the early human gut microbiota composition/development may affect risk factors related to adult health conditions. This concept has fueled the development of strategies to shape the infant microbiota composition based on various functional food products. In this review, we describe the infant microbiota, the mechanisms that drive its establishment and composition, and how microbial consortia may be molded by natural or artificial interventions. Finally, we discuss the relevance of key microbial players of the infant gut microbiota, in particular bifidobacteria, with respect to their role in health and disease.

Influence of Feeding Type on Gut Microbiome Development in Hospitalized Preterm Infants

BACKGROUND

Premature infants have a high risk for dysbiosis of the gut microbiome. Mother's own milk (MOM) has been found to favorably alter gut microbiome composition in infants born at term. Evidence about the influence of feeding type on gut microbial colonization of preterm infants is limited.

OBJECTIVE

The purpose of this study was to explore the effect of feeding types on gut microbial colonization of preterm infants in the neonatal intensive care unit.

METHODS

Thirty-three stable preterm infants were recruited at birth and followed up for the first 30 days of life. Daily feeding information was used to classify infants into six groups (MOM, human donor milk [HDM], Formula, MOM + HDM, MOM + Formula, and HDM + Formula) during postnatal days 0-10, 11-20, and 21-30. Stool samples were collected daily. DNA extracted from stool was used to sequence the 16S rRNA gene. Exploratory data analysis was conducted with a focus on temporal changes of microbial patterns and diversities among infants from different feeding cohorts. Prediction of gut microbial diversity from feeding type was estimated using linear mixed models.

RESULTS

Preterm infants fed MOM (at least 70% of the total diet) had highest abundance of Clostridiales, Lactobacillales, and Bacillales compared to infants in other feeding groups, whereas infants fed primarily HDM or formula had a high abundance of Enterobacteriales compared to infants fed MOM. After controlling for gender, postnatal age, weight, and birth gestational age, the diversity of gut microbiome increased over time and was constantly higher in infants fed MOM relative to infants with other feeding types (p < .01).

DISCUSSION

MOM benefits gut microbiome development of preterm infants, including balanced microbial community pattern and increased microbial diversity in early life.

What's normal? Oligosaccharide concentrations and profiles in milk produced by healthy women vary geographically

Background: Human milk is a complex fluid comprised of myriad substances, with one of the most abundant substances being a group of complex carbohydrates referred to as human milk oligosaccharides (HMOs). There has been some evidence that HMO profiles differ in populations, but few studies have rigorously explored this variability.Objectives: We tested the hypothesis that HMO profiles differ in diverse populations of healthy women. Next, we examined relations between HMO and maternal anthropometric and reproductive indexes and indirectly examined whether differences were likely related to genetic or environmental variations.Design: In this cross-sectional, observational study, milk was collected from a total of 410 healthy, breastfeeding women in 11 international cohorts and analyzed for HMOs by using high-performance liquid chromatography.Results: There was an effect of the cohort (P < 0.05) on concentrations of almost all HMOs. For instance, the mean 3-fucosyllactose concentration was >4 times higher in milk collected in Sweden than in milk collected in rural Gambia (mean ± SEM: 473 ± 55 compared with 103 ± 16 nmol/mL, respectively; P < 0.05), and disialyllacto-N-tetraose (DSLNT) concentrations ranged from 216 ± 14 nmol/mL (in Sweden) to 870 ± 68 nmol/mL (in rural Gambia) (P < 0.05). Maternal age, time postpartum, weight, and body mass index were all correlated with several HMOs, and multiple differences in HMOs [e.g., lacto-N-neotetrose and DSLNT] were shown between ethnically similar (and likely genetically similar) populations who were living in different locations, which suggests that the environment may play a role in regulating the synthesis of HMOs.Conclusions: The results of this study support our hypothesis that normal HMO concentrations and profiles vary geographically, even in healthy women. Targeted genomic analyses are required to determine whether these differences are due at least in part to genetic variation. A careful examination of sociocultural, behavioral, and environmental factors is needed to determine their roles in this regard. This study was registered at clinicaltrials.gov as NCT02670278.

Infant fungal communities: current knowledge and research opportunities

The microbes colonizing the infant gastrointestinal tract have been implicated in later-life disease states such as allergies and obesity. Recently, the medical research community has begun to realize that very early colonization events may be most impactful on future health, with the presence of key taxa required for proper immune and metabolic development. However, most studies to date have focused on bacterial colonization events and have left out fungi, a clinically important sub-population of the microbiota. A number of recent findings indicate the importance of host-associated fungi (the mycobiota) in adult and infant disease states, including acute infections, allergies, and metabolism, making characterization of early human mycobiota an important frontier of medical research. This review summarizes the current state of knowledge with a focus on factors influencing infant mycobiota development and associations between early fungal exposures and health outcomes. We also propose next steps for infant fungal mycobiome research, including longitudinal studies of mother-infant pairs while monitoring long-term health outcomes, further exploration of bacterium-fungus interactions, and improved methods and databases for mycobiome quantitation.

Pathogenesis of NEC: Impact of an altered intestinal microbiome

Necrotizing enterocolitis (NEC), a disease most commonly seen in preterm infants, often presents without warning and is associated with very high mortality and morbidity. Progress in the prevention and treatment of NEC has been slow. In this article, we will discuss some of the reasons as to why this progress has been slow. We will describe some of the factors that appear to be highly associated and important components in the pathophysiology of NEC. We will discuss the intestinal microbial environment of the fetus as well as the preterm infant and how interaction of dysbiosis with an immature gastrointestinal tract combined with dietary factors play a role in the pathogenesis of NEC. Testable hypotheses are discussed as well as how these may lead to not only a better understanding of the pathophysiology of the disease but also the preventative strategies.