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

Extracellular Vesicles with Possible Roles in Gut Intestinal Tract Homeostasis and IBD

The intestinal tract consists of various types of cells, such as epithelial cells, Paneth cells, macrophages, and lymphocytes, which constitute the intestinal immune system and play a significant role in maintaining intestinal homeostasis by producing antimicrobial materials and controlling the host-commensal balance. Various studies have found that the dysfunction of intestinal homeostasis contributes to the pathogenesis of inflammatory bowel disease (IBD). As a novel mediator, extracellular vesicles (EVs) have been recognized as effective communicators, not only between cells but also between cells and the organism. In recent years, EVs have been regarded as vital characters for dysregulated homeostasis and IBD in either the etiology or the pathology of intestinal inflammation. Here, we review recent studies on EVs associated with intestinal homeostasis and IBD and discuss their source, cargo, and origin, as well as their therapeutic effects on IBD, which mainly include artificial nanoparticles and EVs derived from microorganisms.

Mother's Own Milk Feeding and Severity of Respiratory Illness in Acutely Ill Children: An Integrative Review

PROBLEM

Breastfed infants experience less severe infections while actively breastfeeding. However, little is known about whether a history of prior breastfeeding affects severity of illness. Therefore, the purpose of this integrative review was to examine the relationship between previous exposure to mother's own milk (MOM) feeding and severity of respiratory infectious illness in infants and children.

ELIGIBILITY CRITERIA

Studies meeting the following criteria were included: human subjects, term birth, ages 0-35 months at time of study, diagnosis of pneumonia, bronchiolitis or croup, MOM feeding, and statistical analyses reporting separate respiratory infectious illness outcomes when combined with other infections.

SAMPLE

Twelve articles met eligibility criteria.

RESULTS

Major findings were inconsistent definitions of both dose and exposure period of breastfeeding and the severity of illness. In particular, the severity of illness measure was limited by the use of proxy variables such as emergency room visits or hospitalizations that lacked reliability and validity. However, given this limitation, the data suggested that exclusive breastfeeding for four to six months was associated with reduced severity of illness as measured by frequency of visits to the primary care provider office, emergency department or hospitalization.

CONCLUSIONS

Future research in this area should incorporate reliable and valid measures of MOM dose and exposure period and severity of illness outcomes in the critically ill child.

IMPLICATIONS

Among many positive outcomes associated with breastfeeding, an additional talking point for encouragement of exclusive breastfeeding for four to six months may be protective against severe respiratory infectious illness after cessation of breastfeeding.

Evaluation of the Tempo® System: Improving the Microbiological Quality Monitoring of Human Milk

Background: Bacteriological testing of donor human milk is mostly done both before and after pasteurization to control contamination in the end-product and meet the microbiological standards. Although the plate count method represents a reliable and sensitive technique and is considered the gold standard for bacteriological testing, it is recognized for being time-consuming and requiring qualified personnel. Recently, faster testing technologies, mostly geared toward the food industry, have been developed. Among these, the bioMérieux TEMPO® system uses the most probable number method to assess microbiological content in a semi-automated fashion. Objective: The performances of the TEMPO® system in enumerating bacterial quality indicators in human milk were assessed and compared to the reference plate count method. Methods: Naturally and artificially contaminated human milk samples were used to compare the analytical performances of the TEMPO® system to the plate count technique. More specifically, bacteria belonging to the genera Bacillus, Enterobacteriaceae, Staphylococcus aureus, and total aerobic flora were screened using both methods. Bacteria isolated on agar plates containing selective media were identified by supplemental testing. Bacterial testing results and method parameters were compared using linear regression analyses and Bland-Altman approaches. Results: Naturally contaminated milk samples (n = 55) tested for total aerobic flora showed < 1 log (CFU/ml) discrepancy between the two methods in the output results for 98% of the samples. Comparative linear regression analyses demonstrate good correlations between the two methods (R ² > 0.9). At lower levels of bacterial contamination, the TEMPO® method precision (C.V. < 8%) and accuracy (> 83%) were comparable to plate counts. Conclusions: The analytical performances of the TEMPO® system for human milk bacteriological testing are equivalent to the reference plate count method. Results from the TEMPO® system are available within a 24-h turnaround time from sample inoculation without the need for further supplemental testing, suggesting that this semi-automated method could be implemented within milk bank operations as an in-process monitoring technology to optimize end-product quality and safety.

[Research advances in the effect of bioactive substances in breast milk on the growth and development of infants]

There are various types of bioactive substances in human breast milk, such as active proteins, growth factors, cytokines, oligosaccharides, probiotics and cells. Many studies have shown that these bioactive substances in breast milk have important protective effects on infant growth and development, including anti-bacterial and anti-viral effects and the promotion of infant growth and development and immunologic maturation. They can also reduce the incidence rate of infectious diseases in infants, improve neural development in preterm infants, and reduce the risk of obesity and diabetes in future. However, there is still no clinical evidence for the effects of several active substances in breast milk, and their immunoregulatory mechanism remains unclear. Therefore, further studies are needed for clarification.

Gut Microbiota and Obesity: A Role for Probiotics

Nowadays, obesity is one of the most prevalent human health problems. Research from the last 30 years has clarified the role of the imbalance between energy intake and expenditure, unhealthy lifestyle, and genetic variability in the development of obesity. More recently, the composition and metabolic functions of gut microbiota have been proposed as being able to affect obesity development. Here, we will report the current knowledge on the definition, composition, and functions of intestinal microbiota. We have performed an extensive review of the literature, searching for the following keywords: metabolism, gut microbiota, dysbiosis, obesity. There is evidence for the association between gut bacteria and obesity both in infancy and in adults. There are several genetic, metabolic, and inflammatory pathophysiological mechanisms involved in the interplay between gut microbes and obesity. Microbial changes in the human gut can be considered a factor involved in obesity development in humans. The modulation of the bacterial strains in the digestive tract can help to reshape the metabolic profile in the human obese host as suggested by several data from animal and human studies. Thus, a deep revision of the evidence pertaining to the use probiotics, prebiotics, and antibiotics in obese patients is conceivable

Infant growth, neurodevelopment and gut microbiota during infancy: which nutrients are crucial?

PURPOSE OF REVIEW

To update the role of specific nutrients during infant development.

RECENT FINDINGS

Several bioactive nutrients such as long-chain polyunsaturated fatty acids (LC-PUFAs), iron, vitamins, proteins, or carbohydrates have been identified to exert an important role during the first 1000 days of life on infant growth, neurodevelopment, and gut microbiota establishment and maturation. LC-PUFAs are structural constituents of the central nervous system (CNS), being essential in retinal development or hippocampal plasticity. Recently, components of the milk fat globule membrane (MFG) are being added to infant formulas because of their key role in infant's development. A high intake of proteins induces a faster weight gain during infancy which correlates with later obesity. Digestible carbohydrates provide glucose, crucial for an adequate functioning of CNS; nondigestible carbohydrates [e.g. human milk oligosaccharides (HMOs)] are the main carbon source for gut bacteria. Iron-deficiency anemia during infancy has been associated with alterations of mental and psychomotor development. Folate metabolism, closely related to vitamins B6 and B12, controls epigenetic changes, whereas inadequate status of vitamin D affects bone development, but may also increase intestinal permeability and alter gut microbiota composition.

SUMMARY

LC-PUFAs, proteins, carbohydrates, iron, and vitamins during early life are critical for infant's growth, neurodevelopment, and the establishment and functioning of gut microbiota.

Breast Milk-Derived Extracellular Vesicles Enriched in Exosomes From Mothers With Type 1 Diabetes Contain Aberrant Levels of microRNAs

The breast milk plays a crucial role in shaping the initial intestinal microbiota and mucosal immunity of the infant. Interestingly, breastfeeding has proven to be protective against the early onset of immune-mediated diseases including type 1 diabetes. Studies have shown that exosomes from human breast milk are enriched in immune-modulating miRNAs suggesting that exosomal miRNAs (exomiRs) transferred to the infant could play a critical role in the development of the infant's immune system. We extracted exomiRs from breast milk of 52 lactating mothers (26 mothers with type 1 diabetes and 26 healthy mothers), to identify any differences in the exomiR content between the two groups. Small RNA-sequencing was performed to identify known and novel miRNAs in both groups. A total of 631 exomiRs were detected by small RNA sequencing including immune-related miRNAs such as hsa-let-7c, hsa-miR-21, hsa-miR-34a, hsa-miR-146b, and hsa-miR-200b. In addition, ~200 novel miRNAs were identified in both type 1 diabetes and control samples. Among the known miRNAs, nine exomiR's were found differentially expressed in mothers with type 1 diabetes compared to healthy mothers. The highly up-regulated miRNAs, hsa-miR-4497, and hsa-miR-3178, increased lipopolysaccharide-induced expression and secretion of tumor necrosis factor α (TNFα) in human monocytes. The up-regulated miRNA target genes were significantly enriched for longevity-regulating pathways and FoxO signaling. Our findings suggest a role of breast milk-derived exomiRs in modulating the infant's immune system.

Transplant associated infections-The role of the gastrointestinal microbiota and potential therapeutic options

Infectious complications are common following kidney transplantation and rank in the top five causes of death in patients with allograft function. Over the last 5 years, there has been emerging evidence that changes in the gastrointestinal microbiota following kidney transplantation may play a key role in the pathogenesis of transplant-associated infections. Different factors have emerged which may disrupt the interaction between the gastrointestinal microbiota and the immune system, which may lead to infective complications in kidney transplant recipients. Over the last 5 years, there has been emerging evidence that changes in the gastrointestinal microbiota following kidney transplantation may play a key role in the pathogenesis of transplant-associated infections. This review will discuss the structure and function of the gastrointestinal microbiota, the changes that occur in the gastrointestinal microbiota following kidney transplantation and the factors underpinning these changes, how these changes may lead to transplant-associated infectious complications and potential treatments which may be instituted to mitigate this risk.

Maternal Microbiome and Metabolic Health Program Microbiome Development and Health of the Offspring

Maternal nutritional, metabolic, and physiological states, as well as exposure to various environmental factors during conception, gestation, and lactation, have a fundamental role in the health programming of the offspring. Therefore, alterations affecting the maternal microbiota might indirectly influence fetal development. In addition, such alterations could be transmitted to the progeny at different stages of infant development (e.g., preconception, prenatal, or postnatal), thereby favoring the development of an altered microbiota in the neonate. Microbial changes of this kind have been linked to an increased risk of non-communicable diseases (NCDs), including obesity and metabolic syndrome, allergy-related problems, and diabetes. In this review, we summarize the relevance of the maternal microbiota to fetal-neonatal health programming, with a focus on maternal nutritional and metabolic states.

Human Milk Microbiota: Transferring the Antibiotic Resistome to Infants

Commensal bacterial population is believed to be a reservoir for antibiotic resistance genes (ARGs). The infant gut microbiota has relatively higher abundance of ARGs than the adults. These genes can get transferred from commensals to pathogens by horizontal gene transfer, which magnifies the spectrum of antibiotic resistance in the environment. The presence of ARGs in neo-nates and infants, with no prior antibiotic exposure, questions their origin in the naïve commensal population. Breast milk microbiota that is responsible for the initial seeding of infant gut microbiota has also been found to harbour a vast array of ARGs. This review discusses the recent findings that indicate the potential of breast milk microbiota to act as a vehicle for transmission of ARGs to infants.

Maternal Vertical Transmission Affecting Early-life Microbiota Development

The association of the human microbiome with health outcomes has attracted much interest toward its therapeutic manipulation. The likelihood of modulating the human microbiome in early life is high and offers great potential to exert profound effects on human development since the early microbiota shows more flexibility compared to that of adults. The human microbiota, being similar to human genetics, can be transmitted from mother to infant, providing insights into early microbiota acquisition, subsequent development, and potential opportunities for intervention. Here, we review adaptations of the maternal microbiota during pregnancy, birth, and infancy, the acquisition and succession of early-life microbiota, and highlight recent efforts to elucidate mother-to-infant microbiota transmission. We further discuss how the mother-to-infant microbial transmission is shaped; and finally we address potential directions for future studies to promote our understanding within this field.

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.

Strong Multivariate Relations Exist Among Milk, Oral, and Fecal Microbiomes in Mother-Infant Dyads During the First Six Months Postpartum

BACKGROUND

Neonatal gastrointestinal (GI) bacterial community structure may be related to bacterial communities of the mother, including those of her milk. However, very little is known about the diversity in and relationships among complex bacterial communities in mother-infant dyads.

OBJECTIVE

Our primary objective was to assess whether microbiomes of milk are associated with those of oral and fecal samples of healthy lactating women and their infants.

METHODS

Samples were collected 9 times from day 2 to 6 mo postpartum from 21 healthy lactating women and their infants. Milk was collected via complete breast expression, oral samples via swabs, and fecal samples from tissue (mothers) and diapers (infants). Microbiomes were characterized using high-throughput sequencing of the 16S ribosomal RNA (rRNA) gene. Alpha and beta diversity indices were used to compare microbiomes across time and sample types. Membership and composition of microbiomes were analyzed using nonmetric multidimensional scaling and canonical correlation analysis (CCA). The contribution of various bacterial communities of the mother-infant dyad to both milk and infant fecal bacterial communities were estimated using SourceTracker2.

RESULTS

Bacterial community structures were relatively unique to each sample type. The most abundant genus in milk and maternal and infant oral samples was Streptococcus (47.1% ± 2.3%, 53.9% ± 1.3%, and 69.1% ± 1.8%, respectively), whereas Bacteroides were predominant in maternal and infant fecal microbiomes (22.9% ± 1.3% and 21.4% ± 2.4%, respectively). The milk microbiome was more similar to the infant oral microbiome than the infant fecal microbiome. However, CCA suggested strong associations between the complex microbial communities of milk and those of all other sample types collected.

CONCLUSIONS

These findings suggest complex microbial interactions between breastfeeding mothers and their infants and support the hypothesis that variation in the milk microbiome may influence the infant GI microbiome.

MAIT cells, TCR γδ+ cells and ILCs cells in human breast milk and blood from HIV infected and uninfected women

BACKGROUND

Human breast milk cells remain poorly characterized for the presence of unconventional T lymphocytes and innate lymphoid cells (ILCs).

METHODS

Early breast milk was collected from eight HIV-uninfected and 11 HIV-infected women 3-12 days after delivery. Mucosal-associated invariant T cells (MAIT cells), TCR γδ cells, and innate lymphoid cells (ILCs) were analyzed in breast milk and paired blood samples.

RESULTS

CD161+/TRAV1-2 + MAIT cells were detected in breast milk, accounting for a median (IQR) of 0.08% (0.06-0.16) and 0.17% (0.16-0.31) of CD45+ breast milk cells in HIV-uninfected and HIV-infected women, respectively. A selective compartmentalization of γδ T lymphocytes was observed in breast milk. Median (IQR) frequency of γδ T lymphocytes was 8.95% (8.64-12.14) among breast milk lymphocyte cells compared to 2.54% (1.81-4.10) in blood (P = 0.03) in HIV-uninfected women, and 7.26% (4.22-10.54) in breast milk versus 3.31% (2.54-3.80) in blood (P = 0.004) from HIV-infected women. The proportion of group 1 ILC (ILC1) among total ILCs was higher in breast milk compared to blood in HIV-uninfected women (P = 0.03) and HIV-infected women (P = 0.001). The frequency of ILC2 among total ILCs tends to be lower in breast milk compared to blood in HIV-uninfected women (P = 0.06) and HIV-infected women (P = 0.03).

CONCLUSION

Unconventional T cells and ILCs that may be involved in both the protection against infection of the lactating mammary gland and maturation of infant's gut and microbiomes account for a detectable fraction of breast milk cells.

Immunometabolism and Pulmonary Infections: Implications for Protective Immune Responses and Host-Directed Therapies

The biology and clinical efficacy of immune cells from patients with infectious diseases or cancer are associated with metabolic programming. Host immune- and stromal-cell genetic and epigenetic signatures in response to the invading pathogen shape disease pathophysiology and disease outcomes. Directly linked to the immunometabolic axis is the role of the host microbiome, which is also discussed here in the context of productive immune responses to lung infections. We also present host-directed therapies (HDT) as a clinically viable strategy to refocus dysregulated immunometabolism in patients with infectious diseases, which requires validation in early phase clinical trials as adjuncts to conventional antimicrobial therapy. These efforts are expected to be continuously supported by newly generated basic and translational research data to gain a better understanding of disease pathology while devising new molecularly defined platforms and therapeutic options to improve the treatment of patients with pulmonary infections, particularly in relation to multidrug-resistant pathogens.

Repertoire of human breast and milk microbiota: a systematic review

Breastfeeding is a major determinant of human health. Breast milk is not sterile and ecological large-scale sequencing methods have revealed an unsuspected microbial diversity that plays an important role. However, microbiological analysis at the species level has been neglected while it is a prerequisite before understanding which microbe is associated with symbiosis or dysbiosis, and health or disease. We review the currently known bacterial repertoire from the human breast and milk microbiota using a semiautomated strategy. Total 242 articles from 38 countries, 11,124 women and 15,489 samples were included. Total 820 species were identified mainly composed of Proteobacteria and Firmicutes. We report variations according to the analytical method (culture or molecular method), the anatomical site (breast, colostrum or milk) and the infectious status (healthy control, mastitis, breast abscess, neonatal infection). In addition, we compared it with the other human repertoires. Finally, we discuss its putative origin and role in health and disease.

Core Fucosylation of Maternal Milk N-Glycan Evokes B Cell Activation by Selectively Promoting the l-Fucose Metabolism of Gut Bifidobacterium spp. and Lactobacillus spp

This study provides novel evidence for the critical role of maternal milk protein glycosylation in shaping early-life gut microbiota and promoting B cell activation of neonates. The special core-fucosylated oligosaccharides might be promising prebiotics for the personalized nutrition of infants.

The maternal milk glycobiome is crucial for shaping the gut microbiota of infants. Although high core fucosylation catalyzed by fucosyltransferase 8 (Fut8) is a general feature of human milk glycoproteins, its role in the formation of a healthy microbiota has not been evaluated. In this study, we found that the core-fucosylated N-glycans in milk of Chinese mothers selectively promoted the colonization of specific gut microbial groups, such as Bifidobacterium spp. and Lactobacillus spp. in their breast-fed infants during lactation. Compared with Fut8^+/+ (WT) mouse-fed neonates, the offspring fed by Fut8^+/− maternal mice had a distinct gut microbial profile, which was featured by a significant reduction of Lactobacillus spp., Bacteroides spp., and Bifidobacterium spp. and increased abundance of members of the Lachnospiraceae NK4A136 group and Akkermansia spp. Moreover, these offspring mice showed a lower proportion of splenic CD19⁺ CD69⁺ B lymphocytes and attenuated humoral immune responses upon ovalbumin (OVA) immunization. In vitro studies demonstrated that the chemically synthesized core-fucosylated oligosaccharides possessed the ability to promote the growth of tested Bifidobacterium and Lactobacillus strains in minimal medium. The resulting L-fucose metabolites, lactate and 1,2-propanediol, could promote the activation of B cells via the B cell receptor (BCR)-mediated signaling pathway.

The Perturbation of Infant Gut Microbiota Caused by Cesarean Delivery Is Partially Restored by Exclusive Breastfeeding

Early establishment of the infant gut microbiome has been attributed to various environmental factors that may influence long-term health. The aim of this study was to determine the single and combined impacts of the delivery mode, feeding pattern and postnatal antibiotic exposure on the initial establishment of infant gut microbiome at 6 weeks postpartum. A cross-sectional study was conducted at a single center in China. Fecal samples were collected from 120 infants at 6 weeks postpartum. The V3-V4 regions of 16S rRNA gene were analyzed by Illumina sequencing, and clinical information was obtained from medical records and questionnaire survey. Compared with vaginally delivered infants, the gut microbial community structure of cesarean delivered infants were significantly different (P = 0.044), in parallel with the decreased relative abundance of Bifidobacterium (P = 0.028), which contrasts with the normal gut microbial establishment. Using the vaginally delivered and exclusively breastfed (VB) infants as a reference, the comparative analysis of cesarean delivered and exclusively breastfed (CB) infants with cesarean delivered and mixed-fed (CM) infants showed that both within- and between-group UniFrac distance were significantly smaller in CB infants (P < 0.001, P < 0.001). LEfSe analysis showed that the relative abundances of Enterococcus, Veillonella, and Faecalibacterium were significantly different between CB and CM infants, whereas the relative abundances of those genera in VB infants were close to those of CB infants, and distinct from those of CM infants. Additionally, no significant difference of microbial composition, alpha diversity, or community structure was observed between postnatal antibiotics exposed infants and unexposed infants. In summary, delivery mode had a significant impact on the infant gut microbial community structure and composition, and the gut microbiota was disturbed in infants delivered by cesarean section. However, our study showed that this disturbance of gut microbiota in cesarean delivered infants was partially restored by exclusive breastfeeding in comparison with mixed feeding. No distinct impact of postnatal antibiotic exposure on infant gut microbiome was found at 6 weeks of age.

Impact of breast milk on respiratory outcomes in infants with bronchopulmonary dysplasia

BACKGROUND

The objective of our study was to examine whether outpatient respiratory morbidities in infants with bronchopulmonary dysplasia (BPD) are influenced by the human milk consumption.

METHODS

Caregivers of subjects recruited from a BPD clinic completed questionnaires regarding breast milk intake and respiratory outcomes.

RESULTS

One-hundred eighty-eight caregivers completed the questionnaire. Of these, 173 (92.0%) reported that the child received some breast milk. Infants who received breast milk for fewer months were more likely to be non-white, and have a lower household income, public insurance, and secondhand smoke exposure. A longer receipt of breast milk was associated with reduced likelihoods of emergency department visits, systemic steroid courses, and cough or chest congestion, and a trend towards a lower risk of re-hospitalizations.

CONCLUSIONS

Longer duration of breast milk intake was associated with markers of higher socio-economic status, and reduced likelihood of acute and chronic respiratory morbidities among preterm infants with bronchopulmonary dysplasia.

Development and Function of the Intestinal Microbiome and Potential Implications for Pig Production

Simple Summary

Piglet preweaning mortality is a major economic loss and welfare concern for the global pork industry, with the industry average sitting at approximately 15%. As such, novel methods for reducing this mortality are needed. Since research into the intestinal microbiota has provided advances in human health, in particular the impact of early life factors, it was the logical next step to synthesise the existing literature to determine the potential relevance to the pig industry. It is evident from the literature that this area of research provides promising results. However, a large gap within the literature currently exists within the lactation period in pigs. Since optimal development within early life is proving to be critical for human infants, it is crucial that further research is invested into understanding the impact of early life events on a piglet’s microbiome. It is hoped that this review will enable access to critical information for those interested in the microbiome and its potential for improving herd health on the farm.

Abstract

The intestinal microbiota has received a lot of attention in recent times due to its essential role in the immune system development and function. Recent work in humans has demonstrated that the first year of life is the most critical time period for microbiome development with perturbations during this time being proven to have long term health consequences. In this review, we describe the literature surrounding early life events in humans and mice that contribute to intestinal microbiota development and function, and compare this to piglets predominantly during their lactation period, which focuses on the impact lactation management practices may have on the intestinal microbiota. Although extensive research has been conducted in this area in humans and mice, little research exists in pigs during perceivably the most critical time period of development, which is the lactation period. The research reviewed outlines the importance of appropriate intestinal microbiota development. However, further research is needed in order to understand the full extent routine farm practices have on a piglet’s intestinal microbiota.

Exosomes of pasteurized milk: potential pathogens of Western diseases

Milk consumption is a hallmark of western diet. According to common believes, milk consumption has beneficial effects for human health. Pasteurization of cow's milk protects thermolabile vitamins and other organic compounds including bioactive and bioavailable exosomes and extracellular vesicles in the range of 40-120 nm, which are pivotal mediators of cell communication via systemic transfer of specific micro-ribonucleic acids, mRNAs and regulatory proteins such as transforming growth factor-β. There is compelling evidence that human and bovine milk exosomes play a crucial role for adequate metabolic and immunological programming of the newborn infant at the beginning of extrauterine life. Milk exosomes assist in executing an anabolic, growth-promoting and immunological program confined to the postnatal period in all mammals. However, epidemiological and translational evidence presented in this review indicates that continuous exposure of humans to exosomes of pasteurized milk may confer a substantial risk for the development of chronic diseases of civilization including obesity, type 2 diabetes mellitus, osteoporosis, common cancers (prostate, breast, liver, B-cells) as well as Parkinson's disease. Exosomes of pasteurized milk may represent new pathogens that should not reach the human food chain.

Fucosylated Human Milk Oligosaccharides and N-Glycans in the Milk of Chinese Mothers Regulate the Gut Microbiome of Their Breast-Fed Infants during Different Lactation Stages

Human milk glycans provide a broad range of carbon sources for gut microbes in infants. Levels of protein glycosylation in human milk vary during lactation and may also be affected by the stages of gestation and lactation and by the secretor status of the mother. This was the first study to evaluate systematically dynamic changes in human milk oligosaccharides and fucosylated N-glycans in the milk of Chinese mothers with different secretor statuses during 6 months of lactation. Given the unique single nucleotide polymorphism site (rs1047781, A385T) on the fucosyltransferase 2 gene among Chinese populations, our report provides a specific insight into the milk glycobiome of Chinese mothers, which may exert effects on the gut microbiota of infants that differ from findings from other study cohorts.

The milk glycobiome has a significant impact on the gut microbiota of infants, which plays a pivotal role in health and development. Fucosylated human milk oligosaccharides (HMOs) and N-glycans on milk proteins are beneficial for the development of healthy gut microbiota, and the fucosylation levels of these glycans can be affected by the maternal fucosyltransferase 2 gene (FUT2). Here, we present results of longitudinal research on paired milk and stool samples from 56 Chinese mothers (CMs) and their breast-fed children. Changes of HMOs and fucosylated N-glycans in milk of CMs at different lactation stages were detected, which allowed characterization of the major differences in milk glycans and consequential effects on the gut microbiome of infants according to maternal FUT2 status. Significant differences in the abundance of total and fucosylated HMOs between secretor and nonsecretor CMs were noted, especially during early lactation. Despite a tendency toward decreasing milk protein concentrations, the fucosylation levels of milk N-glycans increased during late lactation. The changes in the levels of fucosylated HMOs and milk N-glycans were highly correlated with the growth of Bifidobacterium spp. and Lactobacillus spp. in the gut of infants during early and later lactation, respectively. Enriched expression of genes encoding glycoside hydrolases, glycosyl transferases, ATP-binding cassette (ABC) transporters, and permeases in infants fed by secretor CMs contributed to the promotion of these bacteria in infants. Our data highlight the important role of fucosylated milk glycans in shaping the gut microbiome of infants and provide a solid foundation for development of “personalized” nutrition for Chinese infants.

IMPORTANCE Human milk glycans provide a broad range of carbon sources for gut microbes in infants. Levels of protein glycosylation in human milk vary during lactation and may also be affected by the stages of gestation and lactation and by the secretor status of the mother. This was the first study to evaluate systematically dynamic changes in human milk oligosaccharides and fucosylated N-glycans in the milk of Chinese mothers with different secretor statuses during 6 months of lactation. Given the unique single nucleotide polymorphism site (rs1047781, A385T) on the fucosyltransferase 2 gene among Chinese populations, our report provides a specific insight into the milk glycobiome of Chinese mothers, which may exert effects on the gut microbiota of infants that differ from findings from other study cohorts.

High-Temperature Short-Time Treatment of Human Milk for Bacterial Count Reduction

Background: Human milk (HM) for preterm infants will often be pasteurized for cytomegalovirus (CMV) inactivation and reduction of its bacterial count. High-temperature short-time (HTST) treatment compared to standard Holder pasteurization (HoP) reduces the impact of heat treatment on bioactive HM proteins while effectively inactivating CMV. No data are available for the efficacy of bacterial count reduction using HTST treatments that are available for clinical use. Objective: To test the antiviral and antibacterial efficacy of HTST treatment protocols in HM using a modified HTST treatment device compared to standard HoP. Methods: Holder pasteurized 95 mL HM samples were inoculated with Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), Serratia marcescens (Smarc 00697), two different strains of Klebsiella pneumoniae (ATCC 700603 and Kpn 01605) or spiked with 2 × 105 50% tissue culture infective dose of CMV (AD169) and subsequently subjected to HoP (62.5°C/30 min) or HTST treatment (62°C/5 s, 62°C/15 s, 72°C/5 s, 72°C/15 s, 87°C/2 s, and 87°C/5 s). Bacterial count was determined after treated HM was cultured for 24 h. CMV infectivity was determined by the number of specific CMV immediate early antigen stained nuclei after inoculating human fibroblasts with appropriately prepared HM samples. Results: Holder pasteurized samples revealed no growth after 24 h incubation. Viable bacterial cultures were retrieved from all tested strains after HTST treatment with the default HTST protocol (62°C/5 s) that is available for clinical use. Using other time-temperature combinations, growth rates of S. aureus, E. faecalis, P. aeruginosa, K. pneumoniae, K. pneumonia, and S. marcescens were depending on treatment time, treatment temperature, bacterial genera and strain. Only after treatment temperatures above 72°C no bacterial growth was observed. CMV was inactivated by any tested time-temperature combination. Conclusions: HTST treatment inactivates CMV in 95 mL HM samples but is less effective than HoP in bacterial count reduction at a time-temperature combination of 62°C/5 s. For a reliable bacterial count reduction HTST treatment at 87°C was required in this study.

Metabolomics of Breast Milk: The Importance of Phenotypes

Breast milk is the gold standard of nutrition for newborns. Its composition is tailored to the nutritional needs of the infant and varies between mothers. In recent years, several bioactive molecules have been discovered in addition to the main nutrients, such as multipotent stem cells, hormones, immunoglobulins, and bacteria. Furthermore, the human milk oligosaccharides (HMOs) seem to exert several important protective biological functions. According to the HMOs’ composition, breast milk can be classified as a secretory or non-secretory phenotype. In our study, we investigated the metabolome of milk collected from 58 mothers that delivered neonates at term, that were appropriate, small or large for gestational age, by performing nuclear magnetic resonance spectroscopy (¹H-NMR). From the data analysis, two groups were distinguished based on their different types of oligosaccharides, and classified according the mother phenotype: secretory and non-secretory. This information is of major importance given the different biological function of the different HMOs, such as immune-modulation and protection against disease. This would allow us to predict whether the neonate would be, for instance, more prone to developing certain diseases, and to tailor her or his nutrition to fit their needs perfectly and pave the way to a personalized nutrition.

Immunological Tolerance and Function: Associations Between Intestinal Bacteria, Probiotics, Prebiotics, and Phages

Post-birth there is a bacterial assault on all mucosal surfaces. The intestinal microbiome is an important participant in health and disease. The pattern of composition and concentration of the intestinal microbiome varies greatly. Therefore, achieving immunological tolerance in the first 3-4 years of life is critical for maintaining health throughout a lifetime. Probiotic bacteria are organisms that afford beneficial health effects to the host and in certain instances may protect against the development of disease. The potential benefits of modifying the composition of the intestinal microbial cohort for therapeutic benefit is evident in the use in high risks groups such as premature infants, children receiving antibiotics, rotavirus infections in non-vaccinated children and traveler's diarrhea in adults. Probiotics and prebiotics are postulated to have immunomodulating capabilities by influencing the intestinal microbial cohort and dampening the activity of pathobiont intestinal microbes, such as Klebsiella pneumonia and Clostridia perfringens. Lactobacilli and Bifidobacteria are examples of probiotics found in the large intestine and so far, the benefits afforded to probiotics have varied in efficacy. Most likely the efficacy of probiotic bacteria has a multifactorial dependency, namely on a number of factors that include agents used, the dose, the pattern of dosing, and the characteristics of the host and the underlying luminal microbial environment and the activity of bacteriophages. Bacteriophages, are small viruses that infect and lyse intestinal bacteria. As such it can be posited that these viruses display an effective local protective control mechanism for the intestinal barrier against commensal pathobionts that indirectly may assist the host in controlling bacterial concentrations in the gut. A co-operative activity may be envisaged between the intestinal epithelia, mucosal immunity and the activity of bacteriophages to eliminate pathobiots, highlighting the potential role of bacteriophages in assisting with maintaining intestinal homeostasis. Hence bacteriophage local control of inflammation and immune responses may be an additional immunological defense mechanism that exploits bacteriophage-mucin glycoprotein interactions that controls bacterial diversity and abundance in the mucin layers of the gut. Moreover, and importantly the efficacy of probiotics may be dependent on the symbiotic incorporation of prebiotics, and the abundance and diversity of the intestinal microbiome encountered. The virome may be an important factor that determines the efficacy of some probiotic formulations.

The Effect of Gluten-Free Diet on Health and the Gut Microbiota Cannot Be Extrapolated from One Population to Others

Gluten-related disorders (GRD) affect millions of people worldwide and have been related to the composition and metabolism of the gut microbiota. These disorders present differently in each patient and the only treatment available is a strict life-long gluten-free diet (GFD). Several studies have investigated the effect of a GFD on the gut microbiota of patients afflicted with GRD as well as healthy people. The purpose of this review is to persuade the biomedical community to think that, while useful, the results from the effect of GFD on health and the gut microbiota cannot be extrapolated from one population to others. This argument is primarily based on the highly individualized pattern of gut microbial composition and metabolic activity in each person, the variability of the gut microbiota over time and the plethora of factors associated with this variation. In addition, there is wide variation in the composition, economic viability, and possible deleterious effects to health among different GFD, both within and among countries. Overall, this paper encourages the conception of more collaborative efforts to study local populations in an effort to reach biologically and medically useful conclusions that truly contribute to improve health in patients afflicted with GRD.

Shifts in ovine cardiopulmonary microRNA expression in late gestation and the perinatal period

Background

MicroRNAs (miRNAs) have been identified as important contributors to the regulation of early fetal cardiopulmonary development. However, miRNA expression profiles during late gestation and the early neonatal period are not fully elaborated in large mammals such as sheep (ovis aries). The aim of this study was to sequence miRNA from cardiopulmonary tissues in late gestation and neonate sheep to identify changes in miRNA expression.

Methods

Illumina HiSeq next-generation deep sequencing (NGS) was performed on ovine tissues from the left (LV) and right ventricles (RV), lungs and pulmonary artery (PA) of preterm fetuses (128 days), near-term fetuses (140 days) (term = 148 days) and neonatal lambs (5 days). NGS reads were mapped to the sheep genome (OviAri) and published miRNA sequences.

Results

Of 1345 cardiopulmonary miRNAs that were sequenced, relatively few major shifts in miRNA expression were detected with increased age from near term to neonates, and were confirmed by quantitative real-time PCR: bta-miR-146a (lung), bta-miR-22-3p (lung, LV), hsa-miR-335* (lung, PA), and miR-210 (lung, PA, LV).

Conclusions

Sequencing of miRNA led to identification of four predominant miRNA in ovine cardiopulmonary tissues which alter expression during late gestation and the early neonatal period, concurrent with important functional changes in heart and lungs.

Does Breast Milk Nurture T Lymphocytes in Their Cradle?

Breast feeding has been associated with improved infant outcomes in multiple aspects, including immune outcomes such as infections and potentially atopy and autoimmunity. However associations do not necessarily implicate cause and effect and at this point, exactly how breast feeding and components of breast milk may modulate the infant's immune compartment remains unclear, especially in humans. Some lines of evidence suggest that breastfeeding affects the development of the infant's thymus, a critical organ for T cell development. This may be a direct effect mediated by breast milk components or alternatively, a secondary effect from the impact of breast feeding on the infant's gut microbiome. Here we discuss the potential mechanisms and impact of this association between breast feeding and thymic development.

Breast Milk Cytokines and Early Growth in Gambian Infants

Background: Breast milk provides nutrition for infants but also delivers other bioactive factors that have key protective and developmental benefits. In particular, cytokines are thought to play a role in immunomodulation, although little is known about their impact on health outcomes in early life. Objective: The purpose of this pilot study was to evaluate the relationship between cytokines in breast milk and infant growth outcomes in a low-income setting. Methods: 100 mother-infant pairs were followed up to 2-3 months postpartum as part of a prospective longitudinal cohort study in urban Gambia, West Africa. The concentrations of 9 pro-inflammatory cytokines (IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, IFN-γ, TNFα), IGF-1 and TGFβ2 were measured in colostrum within 12 h of birth and in breast milk at the final visit, scheduled between day 60 and 89 postpartum. Infant weight was recorded and converted to weight-for-age Z-scores (WAZ) at the same time points. Growth outcomes were defined in our study as (a) change in WAZ between birth and final visit (b) WAZ at final visit. Linear regression analysis was used to determine the ability of colostrum and breast milk cytokine concentrations to predict growth outcomes up to 2-3 months postpartum. Results: Gambian infants demonstrated growth faltering across the first 2-3 months postpartum. There was no significant relationship between cytokines in colostrum and subsequent change in WAZ between birth and the final visit, in either unadjusted or adjusted models. However, cytokines in mature breast milk, TNFα, IFNγ, IL1β, IL2, IL4, and IL6, were weak negative predictors of WAZ scores at the final visit, in unadjusted models (p < 0.05). When adjusted for maternal anemia (as a proxy for maternal nutrition), TNFα and IL6 remained significant predictors (p < 0.05). Conclusions: Variations in breast milk cytokine levels do not play a substantial role in the growth faltering observed across early infancy. The potential contribution of other factors, such as micronutrients, hormones or human milk oligosaccharides, must be elucidated. Cytokine levels in mature breast milk were weakly predictive of poor infant growth, possibly reflecting a "read-out" of suboptimal maternal health and nutrition.