Human milk oligosaccharides protect against enteropathogenic Escherichia coli attachment in vitro and EPEC colonization in suckling mice

GlycoMaple: recent updates and applications in visualization and analysis of glycosylation pathways

Post-translational modifications including glycosylation, phosphorylation, and lipidation expand the functionality and diversity of proteins. Protein glycosylation is one of the most abundant post-translational modifications in mammalian cells. The glycosylation process is regulated at multiple steps, including transcription, translation, protein folding, intracellular transport, and localization, and activity of glycosyltransferases and glycoside hydrolases. The glycosylation process is also affected by the concentration of sugar nucleotides in the lumen of the Golgi apparatus. Unlike the synthesis of other biological macromolecules, such as nucleic acids and proteins, glycan biosynthesis is not a template-driven process. In addition, the chemical complexity of glycan structures makes the glycosylation network extraordinarily intricate. We previously developed a web-based tool specially focused on glycan metabolic pathways known as GlycoMaple, which is able to easily visualize and estimate glycosylation pathways based on gene expression data. We recently updated GlycoMaple to incorporate the new genes and glycosylation pathways. Here, we introduce and discuss the uses and upgrades of GlycoMaple.

Modulation of gut-microbiota through probiotics and dietary interventions to improve host health

Dietary patterns play an important role in regards to the modulation and control of the gut microbiome composition and function. The interaction between diet and microbiota plays an important role in order to maintain intestinal homeostasis, which ultimately affect the host's health. Diet directly impacts the microbes that inhabit the gastrointestinal tract (GIT), which then contributes to the production of secondary metabolites, such as short-chain fatty acids, neurotransmitters, and antimicrobial peptides. Dietary consumption with genetically modified probiotics can be the best vaccine delivery vector and protect cells from various illnesses. A holistic approach to disease prevention, treatment, and management takes these intrinsically linked diet-microbes, microbe-microbe interactions, and microbe-host interactions into account. Dietary components, such as fiber can modulate beneficial gut microbiota, and they have resulting ameliorative effects against metabolic disorders. Medical interventions, such as antibiotic drugs can conversely have detrimental effects on gut microbiota by disputing the balance between Bacteroides and firmicute, which contribute to continuing disease states. We summarize the known effects of various dietary components, such as fibers, carbohydrates, fatty acids, vitamins, minerals, proteins, phenolic acids, and antibiotics on the composition of the gut microbiota in this article in addition to the beneficial effect of genetically modified probiotics and consequentially their role in regards to shaping human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Linking human milk oligosaccharide metabolism and early life gut microbiota: bifidobacteria and beyond

SUMMARYHuman milk oligosaccharides (HMOs) are complex, multi-functional glycans present in human breast milk. They represent an intricate mix of heterogeneous structures which reach the infant intestine in an intact form as they resist gastrointestinal digestion. Therefore, they confer a multitude of benefits, directly and/or indirectly, to the developing neonate. Certain bifidobacterial species, being among the earliest gut colonizers of breast-fed infants, have an adapted functional capacity to metabolize various HMO structures. This ability is typically observed in infant-associated bifidobacteria, as opposed to bifidobacteria associated with a mature microbiota. In recent years, information has been gleaned regarding how these infant-associated bifidobacteria as well as certain other taxa are able to assimilate HMOs, including the mechanistic strategies enabling their acquisition and consumption. Additionally, complex metabolic interactions occur between microbes facilitated by HMOs, including the utilization of breakdown products released from HMO degradation. Interest in HMO-mediated changes in microbial composition and function has been the focal point of numerous studies, in recent times fueled by the availability of individual biosynthetic HMOs, some of which are now commonly included in infant formula. In this review, we outline the main HMO assimilatory and catabolic strategies employed by infant-associated bifidobacteria, discuss other taxa that exhibit breast milk glycan degradation capacity, and cover HMO-supported cross-feeding interactions and related metabolites that have been described thus far.

Antimicrobial Properties of Colostrum and Milk

The growing number of antibiotic resistance genes is putting a strain on the ecosystem and harming human health. In addition, consumers have developed a cautious attitude towards chemical preservatives. Colostrum and milk are excellent sources of antibacterial components that help to strengthen the immunity of the offspring and accelerate the maturation of the immune system. It is possible to study these important defenses of milk and colostrum, such as lactoferrin, lysozyme, immunoglobulins, oligosaccharides, etc., as biotherapeutic agents for the prevention and treatment of numerous infections caused by microbes. Each of these components has different mechanisms and interactions in various places. The compound's mechanisms of action determine where the antibacterial activity appears. The activation of the antibacterial activity of milk and colostrum compounds can start in the infant's mouth during lactation and continue in the gastrointestinal regions. These antibacterial properties possess potential for therapeutic uses. In order to discover new perspectives and methods for the treatment of bacterial infections, additional investigations of the mechanisms of action and potential complexes are required.

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.

Non-dairy prebiotics: Conceptual relevance with nutrigenomics and mechanistic understanding of the effects on human health

The increasing health awareness of consumers has made a shift towards vegan and non-dairy prebiotics counterparts. Non-dairy prebiotics when fortified with vegan products have interesting properties and widely found its applications in food industry. The chief vegan products that have prebiotics added include water-soluble plant-based extracts (fermented beverages, frozen desserts), cereals (bread, cookies), and fruits (juices & jelly, ready to eat fruits). The main prebiotic components utilized are inulin, oligofructose, polydextrose, fructooligosaccharides, and xylooligosaccharides. Prebiotics' formulations, type and food matrix affect food products, host health, and technological attributes. Prebiotics from non-dairy sources have a variety of physiological effects that help to prevent and treat chronic metabolic diseases. This review focuses on mechanistic insight on non-dairy prebiotics affecting human health, how nutrigenomics is related to prebiotics development, and role of gene-microbes' interactions. The review will provide industries and researchers with important information about prebiotics, mechanism of non-dairy prebiotics and microbe interaction as well as prebiotic based vegan products.

Necrotizing enterocolitis: recent advances in treatment with translational potential

Necrotizing enterocolitis (NEC) is one of the most prevalent and devastating gastrointestinal disorders in neonates. Despite advances in neonatal care, the incidence and mortality due to NEC remain high, highlighting the need to devise novel treatments for this disease. There have been a number of recent advancements in therapeutic approaches for the treatment of NEC; these involve remote ischemic conditioning (RIC), stem cell therapy, breast milk components (human milk oligosaccharides, exosomes, lactoferrin), fecal microbiota transplantation, and immunotherapy. This review summarizes the most recent advances in NEC treatment currently underway as well as their applicability and associated challenges and limitations, with the aim to provide new insight into the paradigm of care for NEC worldwide.

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.

Recent progress in health effects and biosynthesis of lacto-N-tetraose, the most dominant core structure of human milk oligosaccharide

Human milk oligosaccharides (HMOs), which are a group of complex carbohydrates highly abundant in human milk, have been recognized as critical functional biomolecules for infant health. Lacto-N-tetraose (LNT) is one of the most abundant HMO members and the most dominant core structure of HMO. The promising physiological effects of LNT have been well documented, including prebiotic property, antiadhesive antimicrobial activity, and antiviral effect. Its safety has been evaluated and it has been commercially added to infant formula as a functional ingredient. Because of great commercial importance of LNT, increasing attention has been paid to its highly efficient biological production. In particular, microbial synthesis based on metabolic engineering displays obvious advantages in large-scale production of LNT. This review contains important information about the recent progress in physiological effects, safety evaluation, and biosynthesis of LNT.

Pathophysiology of Enteropathogenic Escherichia coli-induced Diarrhea

Enteropathogenic Escherichia coli (EPEC) are important diarrheal pathogens of infants and young children. Since the availability of molecular diagnosis methods, we now have new insights into the incidence and prevalence of these infections. Recent epidemiological studies indicate that atypical EPEC (aEPEC) are seen more frequently than typical EPEC (tEPEC) worldwide, including in both endemic diarrhea and diarrhea outbreaks. Therefore, it is important to further characterize the pathogenicity of these emerging strains. The virulence mechanisms and pathophysiology of the attaching and effacing lesion (A/E) and the type-three-secretion-system (T3SS) are complex but well-studied. A/E strains use their pool of locus of enterocyte effacement (LEE)-encoded and non-LEE-encoded effector proteins to subvert and modulate cellular and barrier properties of the host. However, the exact mechanisms of diarrhea in EPEC infection are not completely understood. From the clinical perspective, there is a need for fast, easy, and inexpensive diagnostic methods to define optimal treatment and prevention for children in endemic areas. In this article, we present a review of the classification of EPEC, epidemiology, pathogenesis of the disease caused by these bacteria, determinants of virulence, alterations in signaling, determinants of colonization vs. those of disease, and the limited information we have on the pathophysiology of EPEC-induced diarrhea. This article combines peer-reviewed evidence from our own studies and the results of an extensive literature search in the databases PubMed, EMBASE, and Scopus.

Recent advances on human milk oligosaccharide antimicrobial activity

Over the past century, human health has been enhanced by antimicrobial development. Following the deployment of the first antibiotics in the 1940s, bacterial resistance evolved and has increasingly outmaneuvered even the most promising antimicrobial agents. Accordingly, increased interest has been placed on alternative methods to circumvent antimicrobial resistance evolution. In the enclosed short review, we discuss the antimicrobial properties of human breast milk with a special emphasis on human milk oligosaccharides (HMOs). We recount studies across gram-negative and gram-positive pathogens, highlighting the usage of HMOs in promoting human health and wellness.

2'-Fucosyllactose Suppresses Angiogenesis and Alleviates Toxic Effects of 5-Fu in a HCT116 Colon Tumor-Bearing Model

The present study was aimed at examining the anti-tumor effects and molecular mechanisms of 2'-fucosyllactose (2'-FL). At the beginning, the viabilities of four types of colon cancer cells were analyzed after exposure to increasing concentrations of 2'-FL, and HCT116 cells were selected as the sensitive ones, which were applied in the further experiments; then, interestingly, 2'-FL (102.35 µM) was found to induce apoptosis of HCT116 cells, which coincides with significant changes in VEGFA/VEGFR2/p-PI3K/p-Akt/cleaved Caspase3 proteins. Next, in a tumor-bearing nude mouse model, HCT116 was chosen as the sensitive cell line, and 5-fluorouracil (5-Fu) was chosen as the positive medicine. It was noteworthy that both 2'-FL group (2.41 ± 0.57 g) and 2'FL/5-Fu group (1.22 ± 0.35 g) had a significantly lower tumor weight compared with the control (3.87 ± 0.79 g), suggesting 2'-FL could inhibit colon cancer. Since 2'-FL reduced the number of new blood vessels and the malignancy of tumors, we confirmed that 2'-FL effectively inhibited HCT116 tumors, and its mechanism was achieved by regulating the VEGFA/VEGFR2/PI3K/Akt/Caspase3 pathway. Moreover, though HE staining and organ index measurement, 2'-FL was validated to alleviate toxic effects on liver and kidney tissue when combining with 5-Fu. In conclusion, 2'-FL had certain anti-tumor and detoxification effects.

Lifestyle, behaviour, and environmental modification for the management of patients with inflammatory bowel diseases: an International Organization for Study of Inflammatory Bowel Diseases consensus

Environmental and lifestyle factors play an important role in the natural history of Crohn's disease and ulcerative colitis. A group of international experts from the International Organization for the Study of Inflammatory Bowel Diseases voted on a series of consensus statements to inform the management of inflammatory bowel disease (IBD). The recommendations include avoiding traditional cigarette smoking in patients with Crohn's disease or ulcerative colitis, screening for symptoms of depression, anxiety, and psychosocial stressors at diagnosis and during flares (with referral to mental health professionals when appropriate), and encouraging regular physical activity as tolerated. Patients using dietary approaches for treatment of their IBD should be encouraged to adopt diets that are best supported by evidence and involve monitoring for the objective resolution of inflammation. We recommend formal assessment for obesity and nutritional deficiencies, and patients should be encouraged to maintain a normal body-mass index. A shared decision-making approach to contraception should include the consideration of IBD-related factors, and risk factors for venous thromboembolism. Long-term or frequent use of high-dose non-steroidal anti-inflammatory drugs should be avoided. For primary prevention of disease in the offspring of patients with IBD, we recommend avoiding passive exposure to tobacco, using antibiotics judiciously, and considering breastfeeding when able.

Human Milk Oligosaccharides Impact Cellular and Inflammatory Gene Expression and Immune Response

Human milk harbors complex carbohydrates, including human milk oligosaccharides (HMOs), the third most abundant component after lactose and lipids. HMOs have been shown to impact intestinal microbiota, modulate the intestinal immune response, and prevent pathogenic bacterial binding by serving as decoy receptors. However, the direct effect of HMOs on intestinal function and immunity remains to be elucidated. To address this knowledge gap, 21-day-old germ-free mice (C57BI/6) were orally gavaged with 15 mg/day of pooled HMOs for 7 or 14 days and euthanized at day 28 or 35. A set of mice was maintained until day 50 to determine the persistent effects of HMOs. Control groups were maintained in the isolators for 28, 35, or 50 days of age. At the respective endpoints, intestinal tissues were subjected to histomorphometric and transcriptomic analyses, while the spleen and mesenteric lymph nodes (MLNs) were subjected to flow cytometric analysis. The small intestine (SI) crypt was reduced after HMO treatment relative to control at days 28 and 35, while the SI villus height and large intestine (LI) gland depth were decreased in the HMO-treated mice relative to the control at day 35. We report significant HMO-induced and location-specific gene expression changes in host intestinal tissues. HMO treatment significantly upregulated genes involved in extracellular matrix, protein ubiquitination, nuclear transport, and mononuclear cell differentiation. CD4+ T cells were increased in both MLNs and the spleen, while CD8+ T cells were increased in the spleen at day 50 in the HMO group in comparison to controls. In MLNs, plasma cells were increased in HMO group at days 28 and 35, while in the spleen, only at day 28 relative to controls. Macrophages/monocytes and neutrophils were lower in the spleen of the HMO group at days 28, 35, and 50, while in MLNs, only neutrophils were lower at day 50 in the 14-day HMO group. In addition, diphtheria toxoid and tetanus toxoid antibody-secreting cells were higher in HMO-supplemented group compared to controls. Our data suggest that HMOs have a direct effect on gastrointestinal tract metabolism and the immune system even in the absence of host microbiota.

Multiomics to elucidate inflammatory bowel disease risk factors and pathways

Inflammatory bowel disease (IBD) is an immune-mediated disease of the intestinal tract, with complex pathophysiology involving genetic, environmental, microbiome, immunological and potentially other factors. Epidemiological data have provided important insights into risk factors associated with IBD, but are limited by confounding, biases and data quality, especially when pertaining to risk factors in early life. Multiomics platforms provide granular high-throughput data on numerous variables simultaneously and can be leveraged to characterize molecular pathways and risk factors for chronic diseases, such as IBD. Herein, we describe omics platforms that can advance our understanding of IBD risk factors and pathways, and available omics data on IBD and other relevant diseases. We highlight knowledge gaps and emphasize the importance of birth, at-risk and pre-diagnostic cohorts, and neonatal blood spots in omics analyses in IBD. Finally, we discuss network analysis, a powerful bioinformatics tool to assemble high-throughput data and derive clinical relevance.

Full breastfeeding protection against common enteric bacteria and viruses: results from the MAL-ED cohort study

BACKGROUND

Breastfeeding is known to reduce the risk of enteropathogen infections, but protection from specific enteropathogens is not well characterized.

OBJECTIVE

The aim was to estimate the association between full breastfeeding (days fed breast milk exclusively or with nonnutritive liquids) and enteropathogen detection.

METHODS

A total of 2145 newborns were enrolled at 8 sites, of whom 1712 had breastfeeding and key enteropathogen data through 6 mo. We focused on 11 enteropathogens: adenovirus 40/41, norovirus, sapovirus, astrovirus, and rotavirus, enterotoxigenic Escherichia coli (ETEC), Campylobacter spp., and typical enteropathogenic E. coli as well as entero-aggregative E. coli, Shigella and Cryptosporidium. Logistic regression was used to estimate the risk of enteropathogen detection in stools and survival analysis was used to estimate the timing of first detection of an enteropathogen.

RESULTS

Infants with 10% more days of full breastfeeding within the preceding 30 d of a stool sample were less likely to have the 3 E. coli and Campylobacter spp. detected in their stool (mean odds: 0.92-0.99) but equally likely (0.99-1.02) to have the viral pathogens detected in their stool. A 10% longer period of full breastfeeding from birth was associated with later first detection of the 3 E. coli, Campylobacter, adenovirus, astrovirus, and rotavirus (mean HRs of 0.52-0.75). The hazards declined and point estimates were not statistically significant at 3 mo.

CONCLUSIONS

In this large multicenter cohort study, full breastfeeding was associated with lower likelihood of detecting 4 important enteric pathogens in the first 6 mo of life. These results also show that full breastfeeding is related to delays in the first detection of some bacterial and viral pathogens in the stool. As several of these pathogens are risk factors for poor growth during childhood, this work underscores the importance of exclusive or full breastfeeding during the first 6 mo of life to optimize early health.

2'-Fucosyllactose Ameliorates Inflammatory Bowel Disease by Modulating Gut Microbiota and Promoting MUC2 Expression

Gut microbiota dysbiosis, together with goblet cells dysfunction has been observed in ulcerative colitis cases. This study aims to evaluate the potential of 2'-fucosyllactose (2'-FL) supplementation in inhibiting intestinal inflammation through regulating gut microbiota, protecting goblet cells, and stimulating mucin secretion. 2'-FL was orally administered to C57BL/6J mice daily (400 mg/kg bw) for 21 days and 5% dextran sulfate sodium (DSS) was used to induce the colitis in the last 7 days. Meanwhile, fecal microbiota transplantation (FMT) was conducted to test the roles of gut microbiota in the remission of colitis by 2'-FL. Gut microbiota alteration was analyzed through 16S ribosomal RNA (16S rRNA) sequencing. Periodic acid-Schiff (PAS), immunofluorescence staining, as well as mucin 2 (MUC2) and NOD-like receptor family pyrin domain containing 6 (NLRP6) messenger RNA (mRNA) expression in colon fragments was performed and detected. The results showed that the DSS + 2'-FL mice were found to have a slower rate of weight loss, lower disease activity index (DAI) scores, and longer colon lengths than the DSS group (p < 0.05), so in the FMT recipient mice which received fecal microbiota from the DSS + 2'-FL group. In addition, the data revealed that 2'-FL relieved the disorder of DSS-induced gut microbiota, including decreasing the high abundance of mucin-utilizing bacteria in the DSS group, such as Bacteroides, Lachnospiraceae NK4A136, Lachnospiraceae, and Bacteroides vulgatus. PAS and immunofluorescence staining showed that 2'-FL treatment promoted the recovery of goblet cells and enhanced MUC2 and NLRP6 expression, which was also observed in the FM (DSS + 2'-FL) group. Moreover, NLRP6, which has been proved to be a negative regulator for Toll-like receptor 4/myeloid differential protein-8/nuclear factor-kappa B (TLR4/MyD88/NF-κB) pathway, was upregulated by 2'-FL in colon tissue. In conclusion, this study suggests that 2'-FL ameliorates colitis in a gut microbiota-dependent manner. The underlying protective mechanism associates with the recovery of goblet cells number and improves MUC2 secretion through TLR4-related pathway.

Human Milk Oligosaccharides Reduce Murine Group B Streptococcus Vaginal Colonization with Minimal Impact on the Vaginal Microbiota

Group B Streptococcus (GBS) colonizes the vaginal mucosa of a significant percentage of healthy women and is a leading cause of neonatal bacterial infections. Currently, pregnant women are screened in the last month of pregnancy, and GBS-positive women are given antibiotics during parturition to prevent bacterial transmission to the neonate. Recently, human milk oligosaccharides (HMOs) isolated from breastmilk were found to inhibit GBS growth and biofilm formation in vitro, and women that make certain HMOs are less likely to be vaginally colonized with GBS. Using in vitro human vaginal epithelial cells and a murine vaginal colonization model, we tested the impact of HMO treatment on GBS burdens and the composition of the endogenous microbiota by 16S rRNA amplicon sequencing. HMO treatment reduced GBS vaginal burdens in vivo with minimal alterations to the vaginal microbiota. HMOs displayed potent inhibitory activity against GBS in vitro, but HMO pretreatment did not alter adherence of GBS or the probiotic Lactobacillus rhamnosus to human vaginal epithelial cells. In addition, disruption of a putative GBS glycosyltransferase (Δsan_0913) rendered the bacterium largely resistant to HMO inhibition in vitro and in vivo but did not compromise its adherence, colonization, or biofilm formation in the absence of HMOs. We conclude that HMOs are a promising therapeutic bioactive to limit GBS vaginal colonization with minimal impacts on the vaginal microenvironment.

IMPORTANCE During pregnancy, GBS ascension into the uterus can cause fetal infection or preterm birth. In addition, GBS exposure during labor creates a risk of serious disease in the vulnerable newborn and mother postpartum. Current recommended prophylaxis consists of administering broad-spectrum antibiotics to GBS-positive mothers during labor. Although antibiotics have significantly reduced GBS neonatal disease, there are several unintended consequences, including altered neonatal gut bacteria and increased risk for other types of infection. Innovative preventions displaying more targeted antimicrobial activity, while leaving the maternal microbiota intact, are thus appealing. Using a mouse model, we found that human milk oligosaccharides (HMOs) reduce GBS burdens without perturbing the vaginal microbiota. We conclude that HMOs are a promising alternative to antibiotics to reduce GBS neonatal disease.

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.

Structure-Function Relationships of Human Milk Oligosaccharides on the Intestinal Epithelial Transcriptome in Caco-2 Cells and a Murine Model of Necrotizing Enterocolitis

SCOPE

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency affecting preterm infants. Breastmilk protects against NEC, partly due to human milk oligosaccharides (HMOs). HMO compositions are highly diverse, and it is unclear if anti-NEC properties are specific to carbohydrate motifs. Here, this study compares intestinal epithelial transcriptomes of five synthetic HMOs (sHMOs) and examines structure-function relationships of HMOs on intestinal signaling.

METHODS AND RESULTS

This study interrogates the transcriptome of Caco-2Bbe1 cells in response to five synthetic HMOs (sHMOs) using RNA sequencing: 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3FL), 6'-siallyllactose (6'-SL), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT). Protection against intestinal barrier dysfunction and inflammation occurred in an HMO-dependent manner. Each sHMO exerts a unique set of host transcriptome changes and modulated unique signaling pathways. There is clustering between HMOs bearing similar side chains, with little overlap in gene regulation which is shared by all sHMOs. Interestingly, most sHMOs protect pups against NEC, exerting divergent mechanisms on intestinal cell morphology and inflammation.

CONCLUSIONS

These results demonstrate that while structurally distinct HMOs impact intestinal physiology, their mechanisms of action differ. This finding establishes the first structure-function relationship of HMOs in the context of intestinal cell signaling responses and offers a functional framework by which to screen and design HMO-like compounds.

A one-year study of human milk oligosaccharide profiles in the milk of healthy UK mothers and their relationship to maternal FUT2 genotype

Human milk oligosaccharides (HMOs) are indigestible carbohydrates with prebiotic, pathogen decoy and immunomodulatory activities that are theorized to substantially impact infant health. The objective of this study was to monitor HMO concentrations over 1 year to develop a long-term longitudinal dataset. HMO concentrations in the breast milk of healthy lactating mothers of the Cambridge Baby Growth and Breastfeeding Study (CBGS-BF) were measured at birth, 2 weeks, 6 weeks, 3 months, 6 months and 12 months postpartum. HMO quantification was conducted by high-performance anion-exchange chromatography with pulsed amperometric detection using a newly validated "dilute-and-shoot" method. This technique minimizes sample losses and expedites throughput, making it particularly suitable for the analysis of large sample sets. Varying patterns of individual HMO concentrations were observed with changes in lactation timepoint and maternal secretor status, with the most prominent temporal changes occurring during the first 3 months. These data provide valuable information for the development of human milk banks in view of targeted distribution of donor milk based on infant age. Maternal FUT2 genotype was determined based on identification at single-nucleotide polymorphism rs516246 and compared with the genotype expected based on phenotypic markers in the HMO profile. Surprisingly, two mothers genotyped as secretors produced milk that displayed very low levels of 2'-fucosylated moieties. This unexpected discrepancy between genotype and phenotype suggests that differential enzyme expression may cause substantial variation in HMO profiles between genotypically similar mothers, and current genotypic methods of secretor status determination may require validation with HMO markers from milk analysis.

Building Robust Assemblages of Bacteria in the Human Gut in Early Life

The neonatal body provides a range of potential habitats, such as the gut, for microbes. These sites eventually harbor microbial communities (microbiotas). A "complete" (adult) gut microbiota is not acquired by the neonate immediately after birth. Rather, the exclusive, milk-based nutrition of the infant encourages the assemblage of a gut microbiota of low diversity, usually dominated by bifidobacterial species. The maternal fecal microbiota is an important source of bacterial species that colonize the gut of infants, at least in the short-term. However, development of the microbiota is influenced by the use of human milk (breast feeding), infant formula, preterm delivery of infants, caesarean delivery, antibiotic administration, family details and other environmental factors. Following the introduction of weaning (complementary) foods, the gut microbiota develops in complexity due to the availability of a diversity of plant glycans in fruits and vegetables. These glycans provide growth substrates for the bacterial families (such as members of the Ruminococcaceae and Lachnospiraceae) that, in due course, will dominate the gut microbiota of the adult. Although current data are often fragmentary and observational, it can be concluded that the nutrition that a child receives in early life is likely to impinge not only on the development of the microbiota at that time but also on the subsequent lifelong, functional relationships between the microbiota and the human host. The purpose of this review, therefore, is to discuss the importance of promoting the assemblage of functionally robust gut microbiotas at appropriate times in early life.

Probiotics and prebiotics in atopic dermatitis: Pros and cons (Review)

Atopic dermatitis (AD) represents a chronic inflammatory skin condition in which the skin barrier is impaired; thus, the permeability is increased. Hence, there is a greater risk of allergic sensitization, as well as a higher pH and lower protection against resident microbes. Since this condition is currently increasing among children, it requires further study, as little is known regarding the pathogenesis that makes the skin prone to chronic relapsing inflammation. Trying to standardize the data regarding the use of prebiotics and probiotics in AD, we encountered tremendous variability in the literature data. Literature abounds in conflicting data: studies regarding prophylactic and therapeutic applications, different types of strains and dosages, applications in young children up to 5 years of age and above, usage of probiotics alone, prebiotics alone or synbiotics combined. There are also conflicting data regarding the outcome of these studies; some confirming a positive effect of prebiotics, probiotics or synbiotics and some showing no efficacy at all. The articles were divided into those assessing probiotics or prebiotics alone and a combination of the two, with studies showing a positive effect and studies proving no efficacy at all. We tried to critically analyze those articles showing weak and strong points. In summary, the most studied probiotics were the strains of Lactobacilli and Bifidobacteria. The Severity Scoring of Atopic Dermatitis (SCORAD) index was used to measure the efficacy of the treatment. Most studies compared their results with a placebo group and the efficacy when seen in moderate to severe forms of AD in patients with other allergic diseases present. However, the results are difficult to interpret, as in many studies the authors suggest that the disease may have a tendency to improve in time in some groups of patients.

Extraction and Quantitative Analysis of Goat Milk Oligosaccharides: Composition, Variation, Associations, and 2'-FL Variability

Human milk oligosaccharides (hMOS) are associated with health benefits for newborns. We studied the composition of goat MOS (gMOS) from colostrum up to the 9th month of lactation to conceive an overview of the structures present and their fate. Potential correlations with factors such as age, parity, and lifetime milk production were examined. An effective method for gMOS extraction and ultra-high-performance liquid chromatography coupled to fluorescence detection (UPLC-FLD) analysis was established, following 2-aminobenzamide gMOS labeling. Considerable biological variability was highlighted among the 12 quantified gMOS and the 9 non-quantified structures in the individual milk samples. Most characteristic, 2'-fucosyllactose was present in 73.7% of the milk samples analyzed, suggesting the possibility of a secretor/non-secretor goat genotype, similar to humans. Contributing factors to the observed biological variability were goat age, parity, lifetime milk production, and the kids' sex. The results significantly contribute to the current understanding of (variations in) gMOS composition.

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.

Restoration of dysbiotic human gut microbiome for homeostasis

The human microbiome is a complex and dynamic ecosystem, and the imbalance of its microbial community structure from the normal state is termed dysbiosis. The dysbiotic gut microbiome has been proved to be related to several pathological conditions like Inflammatory Bowel Disease (IBD), Irritable Bowel Syndrome (IBS), Colorectal Cancer (CRC), etc., and several other extra-intestinal conditions like Type 1 & 2 diabetes, obesity, etc. The complex gut microbial ecosystem starts to build before the birth of an individual. It is known to get affected by several factors such as birth mode, individual lifestyle, dietary practices, medications, and antibiotics. A dysbiotic microbiome can potentially hamper host homeostasis due to its role in immune modulation, metabolism, nutrient synthesis, etc. Restoration of the dysbiotic gut microbiome has emerged as a promising aid and a better therapeutic approach. Several approaches have been investigated to achieve this goal, including prebiotics and probiotics, Fecal Microbiota Transplantation (FMT), extracellular vesicles, immune modulation, microbial metabolites, dietary interventions, and phages. This review discusses the various factors that influence the human microbiome with respect to their cause-effect relationship and the effect of gut microbiome compositional changes on the brain through the gut-brain axis. We also discuss the practices used globally for gut microbiome restoration purposes, along with their effectiveness.

Non-Digestible Oligosaccharides and Short Chain Fatty Acids as Therapeutic Targets against Enterotoxin-Producing Bacteria and Their Toxins

Enterotoxin-producing bacteria (EPB) have developed multiple mechanisms to disrupt gut homeostasis, and provoke various pathologies. A major part of bacterial cytotoxicity is attributed to the secretion of virulence factors, including enterotoxins. Depending on their structure and mode of action, enterotoxins intrude the intestinal epithelium causing long-term consequences such as hemorrhagic colitis. Multiple non-digestible oligosaccharides (NDOs), and short chain fatty acids (SCFA), as their metabolites produced by the gut microbiota, interact with enteropathogens and their toxins, which may result in the inhibition of the bacterial pathogenicity. NDOs characterized by diverse structural characteristics, block the pathogenicity of EPB either directly, by inhibiting bacterial adherence and growth, or biofilm formation or indirectly, by promoting gut microbiota. Apart from these abilities, NDOs and SCFA can interact with enterotoxins and reduce their cytotoxicity. These anti-virulent effects mostly rely on their ability to mimic the structure of toxin receptors and thus inhibiting toxin adherence to host cells. This review focuses on the strategies of EPB and related enterotoxins to impair host cell immunity, discusses the anti-pathogenic properties of NDOs and SCFA on EPB functions and provides insight into the potential use of NDOs and SCFA as effective agents to fight against enterotoxins.

Evaluation of a novel animal milk oligosaccharide biosimilar: macronutrient digestibility and gastrointestinal tolerance, fecal metabolites, and fecal microbiota of healthy adult dogs and in vitro genotoxicity assays

Milk oligosaccharides (MO) are bioactive compounds in mammalian milk that provide health benefits to neonates beyond essential nutrients. GNU100, a novel animal MO biosimilar, was recently tested in vitro, with results showing beneficial shifts in microbiota and increased short-chain fatty acid (SCFA) production, but other effects of GNU100 were unknown. Three studies were conducted to evaluate the safety, palatability, and gastrointestinal (GI) tolerance of GNU100. In study 1, the mutagenic potential of GNU100 was tested using a bacterial reverse mutation assay and a mammalian cell micronucleus test. In study 2, palatability was assessed by comparing diets containing 0% vs. 1% GNU100 in 20 adult dogs. In study 3, 32 adult dogs were used in a completely randomized design to assess the safety and GI tolerance of GNU100 and explore utility. Following a 2-wk baseline, dogs were assigned to one of four treatments and fed for 26 wk: 0%, 0.5%, 1%, and 1.5% GNU100. On weeks 2, 4, and 26, fresh fecal samples were collected to measure stool quality, immunoglobulin A, and calprotectin, and blood samples were collected to measure serum chemistry, inflammatory markers, and hematology. On weeks 2 and 4, fresh fecal samples were collected to measure metabolites and microbiota. On week 4, total feces were collected to assess apparent total tract macronutrient digestibility. Although revertant numbers were greater compared with the solvent control in tester strain WP2uvrA(pKM101) in the presence of metabolic activation (S9) in the initial experiment, they remained below the threshold for a positive mutagenic response in follow-up confirmatory tests, supporting that GNU100 is not mutagenic. Similarly, no cytotoxicity or chromosome damage was observed in the cell micronucleus test. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05; 3.6:1 consumption ratio) over the control. In study 3, all dogs were healthy and had no signs of GI intolerance or illness. All diets were well accepted, and food intake, fecal characteristics, metabolite concentrations, and macronutrient digestibilities were not altered. GNU100 modulated fecal microbiota, increasing evenness and Catenibacterium, Megamonas, and Prevotella (SCFA producers) and reducing Collinsella. Overall, the results suggest that GNU100 is palatable and well-tolerated, causes no genotoxicity or adverse effects on health, and beneficially shifts the fecal microbiota, supporting the safety of GNU100 for the inclusion in canine diets.

Impact of dietary components on enteric infectious disease

Diets impact host health in multiple ways and an unbalanced diet could contribute to the initiation or progression of a variety of diseases. Although a wealth of information exists on the connections between diet and chronic metabolic diseases such as cardiovascular disease, diabetes mellitus, etc., how diet influences enteric infectious disease still remain underexplored. The review summarizes the current findings on the link between various dietary components and diverse enteric infectious diseases. Dietary ingredients discussed include macronutrients (carbohydrates, lipids, proteins), micronutrients (vitamins, minerals), and other dietary ingredients (phytonutrients and probiotic supplements). We first describe the importance of enteric infectious diseases and the direct and indirect relationship between diet and enteric infectious diseases. Then we discuss the effects of different dietary components on the susceptibility to or progression of enteric infectious disease. Finally, we delineate current knowledge gap and highlighted future research directions. The literature review revealed that different dietary components affect host resistance to enteric infections through a variety of mechanisms. Dietary components may directly inhibit or bind to enteric pathogens, or indirectly influence enteric infections through modulating immune function and gut microbiota. Elucidating the unique repercussions of different diets on enteric infections in this review may help provide dietary guidelines or design dietary interventions to prevent or alleviate enteric infectious diseases.

Early life gut microbiota is associated with rapid infant growth in Hispanics from Southern California

We aimed to determine if the newborn gut microbiota is an underlying determinant of early life growth trajectories. 132 Hispanic infants were recruited at 1-month postpartum. The infant gut microbiome was characterized using 16S rRNA amplicon sequencing. Rapid infant growth was defined as a weight-for-age z-score (WAZ) change greater than 0.67 between birth and 12-months of age. Measures of infant growth included change in WAZ, weight-for-length z-score (WLZ), and body mass index (BMI) z-scores from birth to 12-months and infant anthropometrics at 12-months (weight, skinfold thickness). Of the 132 infants, 40% had rapid growth in the first year of life. Multiple metrics of alpha-diversity predicted rapid infant growth, including a higher Shannon diversity (OR = 1.83; 95% CI: 1.07-3.29; p = .03), Faith's phylogenic diversity (OR = 1.41, 95% CI: 1.05-1.94; p = .03), and richness (OR = 1.04, 95% CI: 1.01-1.08; p = .02). Many of these alpha-diversity metrics were also positively associated with increases in WAZ, WLZ, and BMI z-scores from birth to 12-months (pall<0.05). Importantly, we identified subsets of microbial consortia whose abundance were correlated with these same measures of infant growth. We also found that rapid growers were enriched in multiple taxa belonging to genera such as Acinetobacter, Collinsella, Enterococcus, Neisseria, and Parabacteroides. Moreover, measures of the newborn gut microbiota explained up to an additional 5% of the variance in rapid growth beyond known clinical predictors (R2 = 0.37 vs. 0.32, p < .01). These findings indicate that a more mature gut microbiota, characterized by increased alpha-diversity, at as early as 1-month of age, may influence infant growth trajectories in the first year of life.

Effect of a novel animal milk oligosaccharide biosimilar on macronutrient digestibility and gastrointestinal tolerance, fecal metabolites, and fecal microbiota of healthy adult cats

GNU100 is a novel animal milk oligosaccharide (AMO) biosimilar. In a recent in vitro fermentation study, GNU100 was shown to be fermentable by feline gastrointestinal microbiota and lead to increased short-chain fatty acid production. Our objectives herein were to evaluate the palatability, safety, and gastrointestinal tolerance of GNU100 in healthy adult cats. Exploratory end-points were measured to assess utility. In study 1, 20 adult cats were used to test the palatability of diets containing 0% or 1% GNU100. In study 2, 32 (mean age = 1.9 yr; mean body weight = 4.6 kg) male (n = 12) and female (n = 20) adult cats were used in a completely randomized design. After a 2-wk baseline, cats were assigned to one of the following treatment groups and fed for 26 wk: control (CT, no GNU100), low dose (LD, 0.5% GNU100), medium dose (MD, 1.0% GNU100), and high dose (HD, 1.5% GNU100). On weeks 2, 4, and 26, fresh fecal samples were collected for the measurement of stool quality and immune and inflammatory markers and on weeks 2 and 4 for microbiota and metabolites. On week 4, total feces were collected to measure apparent total tract macronutrient digestibility. On weeks 2, 4, and 26, blood samples were collected for serum chemistry, hematology, and inflammatory marker measurement. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05), with GNU100 having a 17.6:1 consumption ratio compared with control. In the long-term study, all cats remained healthy, without any signs of gastrointestinal intolerance or illness. All diets were well accepted, resulting in similar (P > 0.05) food intake, fecal characteristics, immunoglobulin A, and calprotectin, and dry matter, organic matter, fat, and crude protein digestibilities. Fecal butyrate was greater (P = 0.02) in cats fed HD than cats fed LD or MD. Fecal indole was lower (P = 0.02) in cats fed HD than cats fed LD. Cats fed CT had a higher (P = 0.003) relative abundance of Actinobacteria than cats fed LD. The relative abundance of Peptococcus was impacted by diet and time. At 4 wk, Campylobacter was lower in fecal samples of cats fed HD. Overall, the data suggest that dietary GNU100 supplementation was highly palatable, well tolerated, did not cause detrimental effects on fecal quality or nutrient digestibility, increased fecal butyrate concentrations, and reduced fecal indole concentrations, supporting the safety of GNU100 for inclusion in feline diets and suggesting potential benefits on gastrointestinal health of cats.

Effect of a novel animal milk oligosaccharide biosimilar on the gut microbial communities and metabolites of in vitro incubations using feline and canine fecal inocula

Milk oligosaccharides (MO) confer multiple potential physiological benefits, such as the selective growth promotion of beneficial microbiota, inhibition of enteric pathogen growth and adhesion to enterocytes, maturation of the gut mucosal barrier, and modulation of the gastrointestinal immune system. This study was conducted to determine the fermentation potential of GNU100, an animal MO biosimilar, in an in vitro system using healthy canine and feline fecal inocula. Single feline and single canine fecal samples were used to inoculate a batch fermentation system. Tubes containing a blank control (BNC), GNU100 at 0.5% (5 g/L; GNU1), or GNU100 at 1.0% (10 g/L; GNU2) were incubated for 48 h. Gas pressure, pH, lactate, short-chain fatty acids (SCFA; acetate, propionate, and butyrate), and branched-chain fatty acids (BCFA; isobutyrate, isovalerate, and valerate) were measured after 6, 24, and 48 h. Ammonium and microbiota (total bacteria by flow cytometry and Pet-16Seq; Lactobacillus and Bifidobacterium by quantitative polymerase chain reaction ) were measured after 24 and 48 h. Data were analyzed using the Mixed Models procedure of SAS. Substrates were considered to be a fixed effect and replicates considered to be a random effect. Tukey's multiple comparison analysis was used to compare least squares means, with differences considered significant with P < 0.05. In feline and canine incubations, SCFA increases were greater (P < 0.0001) in GNU100 compared with BNC, with acetate making up the largest SCFA proportion (P < 0.0001). GNU100 cultures led to greater increases (P < 0.0001) in lactate and ammonium than BNC in the feline incubations. GNU100 cultures led to greater increases (P < 0.0001) in ammonium than BNC in canine incubations and greater increases (P < 0.0001) in BCFA than BNC in feline incubations. Pet-16Seq microbial profiles from the feline and canine fecal incubations exhibited a modulation after GNU100 fermentation, with a reduction of the genera Escherichia/Shigella and Salmonella. In feline incubations, Bifidobacterium populations had greater increases (P < 0.0001) in GNU100 than BNC. In feline incubations, Lactobacillus populations had greater increases (P = 0.01) in GNU100 than BNC, with GNU1 leading to greater increases (P = 0.02) in Lactobacillus than BNC tubes in canine incubations. Overall, this study demonstrated that GNU100 was fermented in an in vitro fermentation system inoculated with canine and feline microbiota, resulting in the growth of beneficial bacteria and the production of SCFA, BCFA, and ammonium.

Enteropathogenic Escherichia coli Infection Induces Diarrhea, Intestinal Damage, Metabolic Alterations, and Increased Intestinal Permeability in a Murine Model

Enteropathogenic E. coli (EPEC) are recognized as one of the leading bacterial causes of infantile diarrhea worldwide. Weaned C57BL/6 mice pretreated with antibiotics were challenged orally with wild-type EPEC or escN mutant (lacking type 3 secretion system) to determine colonization, inflammatory responses and clinical outcomes during infection. Antibiotic disruption of intestinal microbiota enabled efficient colonization by wild-type EPEC resulting in growth impairment and diarrhea. Increase in inflammatory biomarkers, chemokines, cellular recruitment and pro-inflammatory cytokines were observed in intestinal tissues. Metabolomic changes were also observed in EPEC infected mice with changes in tricarboxylic acid (TCA) cycle intermediates, increased creatine excretion and shifts in gut microbial metabolite levels. In addition, by 7 days after infection, although weights were recovering, EPEC-infected mice had increased intestinal permeability and decreased colonic claudin-1 levels. The escN mutant colonized the mice with no weight loss or increased inflammatory biomarkers, showing the importance of the T3SS in EPEC virulence in this model. In conclusion, a murine infection model treated with antibiotics has been developed to mimic clinical outcomes seen in children with EPEC infection and to examine potential roles of selected virulence traits. This model can help in further understanding mechanisms involved in the pathogenesis of EPEC infections and potential outcomes and thus assist in the development of potential preventive or therapeutic interventions.

S100A8 and S100A9 Are Important for Postnatal Development of Gut Microbiota and Immune System in Mice and Infants

BACKGROUND & AIMS

After birth, the immune system matures via interactions with microbes in the gut. The S100 calcium binding proteins S100A8 and S100A9, and their extracellular complex form, S100A8-A9, are found in high amounts in human breast milk. We studied levels of S100A8-A9 in fecal samples (also called fecal calprotectin) from newborns and during infancy, and their effects on development of the intestinal microbiota and mucosal immune system.

METHODS

We collected stool samples (n = 517) from full-term (n = 72) and preterm infants (n = 49) at different timepoints over the first year of life (days 1, 3, 10, 30, 90, 180, and 360). We measured levels of S100A8-A9 by enzyme-linked immunosorbent assay and analyzed fecal microbiomes by 16S sRNA gene sequencing. We also obtained small and large intestine biopsies from 8 adults and 10 newborn infants without inflammatory bowel diseases (controls) and 8 infants with necrotizing enterocolitis and measured levels of S100A8 by immunofluorescence microscopy. Children were followed for 2.5 years and anthropometric data and medical information on infections were collected. We performed studies with newborn C57BL/6J wild-type and S100a9^-/- mice (which also lack S100A8). Some mice were fed or given intraperitoneal injections of S100A8 or subcutaneous injections of Staphylococcus aureus. Blood and intestine, mesenterial and celiac lymph nodes were collected; cells and cytokines were measured by flow cytometry and studied in cell culture assays. Colon contents from mice were analyzed by culture-based microbiology assays.

RESULTS

Loss of S100A8 and S100A9 in mice altered the phenotypes of colonic lamina propria macrophages, compared with wild-type mice. Intestinal tissues from neonatal S100-knockout mice had reduced levels of CX3CR1 protein, and Il10 and Tgfb1 mRNAs, compared with wild-type mice, and fewer T-regulatory cells. S100-knockout mice weighed 21% more than wild-type mice at age 8 weeks and a higher proportion developed fatal sepsis during the neonatal period. S100-knockout mice had alterations in their fecal microbiomes, with higher abundance of Enterobacteriaceae. Feeding mice S100 at birth prevented the expansion of Enterobacteriaceae, increased numbers of T-regulatory cells and levels of CX3CR1 protein and Il10 mRNA in intestine tissues, and reduced body weight and death from neonatal sepsis. Fecal samples from term infants, but not preterm infants, had significantly higher levels of S100A8-A9 during the first 3 months of life than fecal samples from adults; levels decreased to adult levels after weaning. Fecal samples from infants born by cesarean delivery had lower levels of S100A8-A9 than from infants born by vaginal delivery. S100 proteins were expressed by lamina propria macrophages in intestinal tissues from infants, at higher levels than in intestinal tissues from adults. High fecal levels of S100 proteins, from 30 days to 1 year of age, were associated with higher abundance of Actinobacteria and Bifidobacteriaceae, and lower abundance of Gammaproteobacteria-particularly opportunistic Enterobacteriaceae. A low level of S100 proteins in infants' fecal samples associated with development of sepsis and obesity by age 2 years.

CONCLUSION

S100A8 and S100A9 regulate development of the intestinal microbiota and immune system in neonates. Nutritional supplementation with these proteins might aide in development of preterm infants and prevent microbiota-associated disorders in later years.

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.

Host Factors of Favorable Intestinal Microbial Colonization

Gut microbial colonization starts with birth and initiates a complex process between the host and the microbiota. Successful co-development of both establishes a symbiotic mutual relationship and functional homeostasis, while alterations thereof predispose the individual life-long to inflammatory and metabolic diseases. Multiple data have been provided how colonizing microbes induce a reprogramming and maturation of immunity by providing crucial instructing information to the newborn immune system. Less is known about what host factors have influence on the interplay between intestinal immunity and the composition of the gut microbial ecology. Here we review existing evidence regarding host factors that contribute to a favorable development of the gut microbiome and thereby successful maturation of gut mucosal immunity.

Effects of Human Milk Oligosaccharides on the Adult Gut Microbiota and Barrier Function

Human milk oligosaccharides (HMOs) shape the gut microbiota in infants by selectively stimulating the growth of bifidobacteria. Here, we investigated the impact of HMOs on adult gut microbiota and gut barrier function using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®), Caco2 cell lines, and human intestinal gut organoid-on-chips. We showed that fermentation of 2'-O-fucosyllactose (2'FL), lacto-N-neotetraose (LNnT), and combinations thereof (MIX) led to an increase of bifidobacteria, accompanied by an increase of short chain fatty acid (SCFA), in particular butyrate with 2'FL. A significant reduction in paracellular permeability of FITC-dextran probe was observed using Caco2 cell monolayers with fermented 2'FL and MIX, which was accompanied by an increase in claudin-8 gene expression as shown by qPCR, and a reduction in IL-6 as determined by multiplex ELISA. Using gut-on-chips generated from human organoids derived from proximal, transverse, and distal colon biopsies (Colon Intestine Chips), we showed that claudin-5 was significantly upregulated across all three gut-on-chips following treatment with fermented 2'FL under microfluidic conditions. Taken together, these data show that, in addition to their bifidogenic activity, HMOs have the capacity to modulate immune function and the gut barrier, supporting the potential of HMOs to provide health benefits in adults.

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.

Exercise-induced 3'-sialyllactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspring

Poor maternal environments, such as under- or overnutrition, can increase the risk for the development of obesity, type 2 diabetes and cardiovascular disease in offspring^1-9. Recent studies in animal models have shown that maternal exercise before and during pregnancy abolishes the age-related development of impaired glucose metabolism^10-15, decreased cardiovascular function¹⁶ and increased adiposity^11,15; however, the underlying mechanisms for maternal exercise to improve offspring's health have not been identified. In the present study, we identify an exercise-induced increase in the oligosaccharide 3'-sialyllactose (3'-SL) in milk in humans and mice, and show that the beneficial effects of maternal exercise on mouse offspring's metabolic health and cardiac function are mediated by 3'-SL. In global 3'-SL knockout mice (3'-SL^-/-), maternal exercise training failed to improve offspring metabolic health or cardiac function in mice. There was no beneficial effect of maternal exercise on wild-type offspring who consumed milk from exercise-trained 3'-SL^-/- dams, whereas supplementing 3'-SL during lactation to wild-type mice improved metabolic health and cardiac function in offspring during adulthood. Importantly, supplementation of 3'-SL negated the detrimental effects of a high-fat diet on body composition and metabolism. The present study reveals a critical role for the oligosaccharide 3'-SL in milk to mediate the effects of maternal exercise on offspring's health. 3'-SL supplementation is a potential therapeutic approach to combat the development of obesity, type 2 diabetes and cardiovascular disease.

Supporting a Healthy Microbiome for the Primary Prevention of Eczema

Eczema is increasing worldwide with associated increases in health costs and decreases in quality of life. There are many factors that are speculated to interact in the development of eczema including genetics and environmental exposures. Prevention of the development of eczema may prevent the further development of food allergies and asthma. This concept has prompted a variety of research into the area of primary prevention of eczema in infants. This exploration includes a growing body of research examining infants supplemented with probiotics, prebiotics, or both (synbiotics) often compared with their breastfed counterparts. The goal of this paper is to examine the evidence for manipulating the microbiome in the prevention of eczema. Several strains of probiotics, compositions of prebiotics, and varied combinations of both are commercially available. Evidence supports altering the microbiome in infants at high risk of atopy who are not able to breastfeed with Lactobacillus strains when given both prenatally followed by prolonged use (greater than 6 months) postnatally for the primary prevention of eczema. Prebiotics have also been shown beneficial for primary prevention of eczema in formula-fed infants with prolonged use greater than 6 months. These findings are in keeping with the World Allergy Organization (WAO) recommendations that support interventions to manipulate the microbiome with both probiotics and prebiotics.

Symposium review: Dairy-derived oligosaccharides-Their influence on host-microbe interactions in the gastrointestinal tract of infants

Oligosaccharides are the third most abundant component in human milk. It is widely accepted that they play several important protective, physiological, and biological roles, including selective growth stimulation of beneficial gut microbiota, inhibition of pathogen adhesion, and immune modulation. However, until recently, very few commercial products on the market have capitalized on these functions. This is mainly because the quantities of human milk oligosaccharides required for clinical trials have been unavailable. Recently, clinical studies have tested the potential beneficial effects of feeding infants formula containing 2'-fucosyllactose, which is the most abundant oligosaccharide in human milk. These studies have opened this field for further well-designed studies, which are required to fully understand the role of human milk oligosaccharides. However, one of the most striking features of human milk is its diversity of oligosaccharides, with over 200 identified to date. It may be that a mixture of oligosaccharides is even more beneficial to infants than a single structure. For this reason, the milk of domestic animals has become a focal point in recent years as an alternative source of complex oligosaccharides with associated biological activity. This review will focus specifically on free oligosaccharides found in bovine and caprine milk and the biological roles associated with such structures. These dairy streams are ideal sources of oligosaccharides, given their wide availability and use in so many regularly consumed dairy products. The aim of this review was to provide an overview of research into the functional role of bovine and caprine milk oligosaccharides in host-microbial interactions in the gut and provide current knowledge related to the isolation of oligosaccharides as ingredients for incorporation in functional or medical foods.

Maternal Human Milk Oligosaccharide Profile Modulates the Impact of an Intervention with Iron and Galacto-Oligosaccharides in Kenyan Infants

There is little data on human milk oligosaccharide (HMO) composition in Sub-Saharan Africa. Iron fortificants adversely affect the infant gut microbiota, while co-provision of prebiotic galacto-oligosaccharides (GOS) mitigates most of the adverse effects. Whether variations in maternal HMO profile can influence the infant response to iron and/or GOS fortificants is unknown. The aim of this study was to determine HMO profiles and the secretor/non-secretor phenotype of lactating Kenyan mothers and investigate their effects on the maternal and infant gut microbiota, and on the infant response to a fortification intervention with 5 mg iron (2.5 mg as sodium iron ethylenediaminetetraacetate and 2.5 mg as ferrous fumarate) and 7.5 g GOS. We studied mother–infant pairs (n = 80) participating in a 4-month intervention trial in which the infants (aged 6.5–9.5 months) received daily a micronutrient powder without iron, with iron or with iron and GOS. We assessed: (1) maternal secretor status and HMO composition; (2) effects of secretor status on the maternal and infant gut microbiota in a cross-sectional analysis at baseline of the intervention trial; and (3) interactions between secretor status and intervention groups during the intervention trial on the infant gut microbiota, gut inflammation, iron status, growth and infectious morbidity. Secretor prevalence was 72% and HMOs differed between secretors and non-secretors and over time of lactation. Secretor status did not predict the baseline composition of the maternal and infant gut microbiota. There was a secretor-status-by-intervention-group interaction on Bifidobacterium (p = 0.021), Z-scores for length-for-age (p = 0.022) and weight-for-age (p = 0.018), and soluble transferrin receptor (p = 0.041). In the no iron group, longitudinal prevalence of diarrhea was higher among infants of non-secretors (23.8%) than of secretors (10.4%) (p = 0.001). In conclusion, HMO profile may modulate the infant gut microbiota response to fortificant iron; compared to infants of secretor mothers, infants of non-secretor mothers may be more vulnerable to the adverse effect of iron but also benefit more from the co-provision of GOS.

Prebiotics: tools to manipulate the gut microbiome and metabolome

The human gut is an ecosystem comprising trillions of microbes interacting with the host. The composition of the microbiota and their interactions play roles in different biological processes and in the development of human diseases. Close relationships between dietary modifications, microbiota composition and health status have been established. This review focuses on prebiotics, or compounds which selectively encourage the growth of beneficial bacteria, their mechanisms of action and benefits to human hosts. We also review advances in synthesis technology for human milk oligosaccharides, part of one of the most well-characterized prebiotic–probiotic relationships. Current and future research in this area points to greater use of prebiotics as tools to manipulate the microbial and metabolic diversity of the gut for the benefit of human health.

Diet-Microbe-Host Interactions That Affect Gut Mucosal Integrity and Infection Resistance

The gastrointestinal tract microbiome plays a critical role in regulating host innate and adaptive immune responses against pathogenic bacteria. Disease associated dysbiosis and environmental induced insults, such as antibiotic treatments can lead to increased susceptibility to infection, particularly in a hospital setting. Dietary intervention is the greatest tool available to modify the microbiome and support pathogen resistance. Some dietary components can maintain a healthy disease resistant microbiome, whereas others can contribute to an imbalanced microbial population, impairing intestinal barrier function and immunity. Characterizing the effects of dietary components through the host-microbe axis as it relates to gastrointestinal health is vital to provide evidence-based dietary interventions to mitigate infections. This review will cover the effect of dietary components (carbohydrates, fiber, proteins, fats, polyphenolic compounds, vitamins, and minerals) on intestinal integrity and highlight their ability to modulate host-microbe interactions as to improve pathogen resistance.

Human Milk Oligosaccharides Increase Mucin Expression in Experimental Necrotizing Enterocolitis

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.

Recent progress of porcine milk components and mammary gland function

As the only nutritional source for newborn piglets, porcine colostrum and milk contain critical nutritional and immunological components including carbohydrates, lipids, and proteins (immunoglobulins). However, porcine milk composition is more complex than these three components. Recently, scientists identified additional and novel components of sow colostrum and milk, including exosomes, oligosaccharides, and bacteria, which possibly act as biological signals and modulate the intestinal environment and immune status in piglets and later in life. Evaluation of these nutritional and non-nutritional components in porcine milk will help better understand the nutritional and biological function of porcine colostrum and milk. Furthermore, some important functions of the porcine mammary gland have been reported in recent published literature. These preliminary studies hypothesized how glucose, amino acids, and fatty acids are transported from maternal blood to the porcine mammary gland for milk synthesis. Therefore, we summarized recent reports on sow milk composition and porcine mammary gland function in this review, with particular emphasis on macronutrient transfer and synthesis mechanisms, which might offer a possible approach for regulation of milk synthesis in the future.

Low Diversity of Human Milk Oligosaccharides is Associated with Necrotising Enterocolitis in Extremely Low Birth Weight Infants

Difference in human milk oligosaccharides (HMO) composition in breast milk may be one explanation why some preterm infants develop necrotizing enterocolitis (NEC) despite being fed exclusively with breast milk. The aim of this study was to measure the concentration of 15 dominant HMOs in breast milk during the neonatal period and investigate how their levels correlated to NEC, sepsis, and growth in extremely low birth weight (ELBW; <1000 g) infants who were exclusively fed with breast milk. Milk was collected from 91 mothers to 106 infants at 14 and 28 days and at postmenstrual week 36. The HMOs were analysed with high-performance anion-exchange chromatography with pulsed amperometric detection. The HMOs diversity and the levels of Lacto-N-difucohexaose I were lower in samples from mothers to NEC cases, as compared to non-NEC cases at all sampling time points. Lacto-N-difucohexaose I is only produced by secretor and Lewis positive mothers. There were also significant but inconsistent associations between 3′-sialyllactose and 6′-sialyllactose and culture-proven sepsis and significant, but weak correlations between several HMOs and growth rate. Our results suggest that the variation in HMO composition in breast milk may be an important factor explaining why exclusively breast milk fed ELBW infants develop NEC.

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).