Association Between Breastmilk Microbiota and Food Allergy in Infants

Environmental and structural factors associated with bacterial diversity in household dust across the Arizona-Sonora border

We previously reported that asthma prevalence was higher in the United States (US) compared to Mexico (MX) (25.8% vs. 8.4%). This investigation assessed differences in microbial dust composition in relation to demographic and housing characteristics on both sides of the US-MX Border. Forty homes were recruited in the US and MX. Home visits collected floor dust and documented occupants' demographics, asthma prevalence, housing structure, and use characteristics. US households were more likely to have inhabitants who reported asthma when compared with MX households (30% vs. 5%) and had significantly different flooring types. The percentage of households on paved roads, with flushing toilets, with piped water and with air conditioning was higher in the US, while dust load was higher in MX. Significant differences exist between countries in the microbial composition of the floor dust. Dust from Mexican homes was enriched with Alishewanella, Paracoccus, Rheinheimera genera and Intrasporangiaceae family. A predictive metagenomics analysis identified 68 significantly differentially abundant functional pathways between US and MX. This study documented multiple structural, environmental, and demographic differences between homes in the US and MX that may contribute to significantly different microbial composition of dust observed in these two countries.

Human Milk Oligosaccharides: A Critical Review on Structure, Preparation, Their Potential as a Food Bioactive Component, and Future Perspectives

Human milk is the gold standard for infant feeding. Human milk oligosaccharides (HMOs) are a unique group of oligosaccharides in human milk. Great interest in HMOs has grown in recent years due to their positive effects on various aspects of infant health. HMOs provide various physiologic functions, including establishing a balanced infant's gut microbiota, strengthening the gastrointestinal barrier, preventing infections, and potential support to the immune system. However, the clinical application of HMOs is challenging due to their specificity to human milk and the difficulties and high costs associated with their isolation and synthesis. Here, the differences in oligosaccharides in human and other mammalian milk are compared, and the synthetic strategies to access HMOs are summarized. Additionally, the potential use and molecular mechanisms of HMOs as a new food bioactive component in different diseases, such as infection, necrotizing enterocolitis, diabetes, and allergy, are critically reviewed. Finally, the current challenges and prospects of HMOs in basic research and application are discussed.

Gut Microbiota to Microglia: Microbiome Influences Neurodevelopment in the CNS

The brain is traditionally viewed as an immunologically privileged site; however, there are known to be multiple resident immune cells that influence the CNS environment and are reactive to extra-CNS signaling. Microglia are an important component of this system, which influences early neurodevelopment in addition to modulating inflammation and regenerative responses to injury and infection. Microglia are influenced by gut microbiome-derived metabolites, both as part of their normal function and potentially in pathological patterns that may induce neurodevelopmental disabilities or behavioral changes. This review aims to summarize the mounting evidence indicating that, not only is the Gut-Brain axis mediated by metabolites and microglia throughout an organism's lifetime, but it is also influenced prenatally by maternal microbiome and diet, which holds implications for both early neuropathology and neurodevelopment.

Importance of human milk for infants in the clinical setting: Updates and mechanistic links

INTRODUCTION

Human milk (HM) is the optimal source of nutrition for infants and has been implicated in multiple aspects of infant health. Although much of the existing literature has focused on the individual components that drive its nutrition content, examining HM as a biological system is needed for meaningful advancement of the field. Investigation of the nonnutritive bioactive components of HM and the maternal, infant, and environmental factors which affect these bioactives is important to better understand the importance of HM provision to infants. This information may inform care of clinical populations or infants who are critically ill, hospitalized, or who have chronic diseases and may benefit most from receiving HM.

METHODS

In this narrative review, we reviewed literature examining maternal and infant influences on HM composition with a focus on studies published in the last 10 years that were applicable to clinical populations.

RESULTS

We found multiple studies examining HM components implicated in infant immune and gut health and neurodevelopment. Additional work is needed to understand how donor milk and formula may be used in situations of inadequate maternal HM. Furthermore, a better understanding of how maternal factors such as maternal genetics and metabolic health influence milk composition is needed.

CONCLUSION

In this review, we affirm the importance of HM for all infants, especially clinical populations. An understanding of how HM composition is modulated by maternal and environmental factors is important to progress the field forward with respect to mechanistic links between HM biology and infant health outcomes.

Environmental and Structural Factors Associated with Bacterial Diversity in Household Dust Across the Arizona-Sonora Border

We previously reported that asthma prevalence was higher in the United States (US) compared to Mexico (MX) (25.8% vs 8.4%). This investigation assessed differences in microbial dust composition in relation to demographic and housing characteristics on both sides of the US-MX Border. Forty homes were recruited in the US and MX. Home visits collected floor dust and documented occupants' demographics, asthma prevalence, and housing structure and use characteristics. US households were more likely to have inhabitants who reported asthma when compared with MX households (30% vs 5%) and had significantly different flooring types. The percentage of households on paved roads, with flushing toilets, with piped water and with air conditioning was higher in the US, while dust load was higher in MX. Significant differences exist between countries in the microbial composition of the floor dust. Dust from US homes was enriched with Geodermatophilus, whereas dust from Mexican homes was enriched with Alishewanella and Chryseomicrobium. A predictive metagenomics analysis identified 68 significantly differentially abundant functional pathways between US and MX. This study documented multiple structural, environmental, and demographic differences between homes in the US and MX that may contribute to significantly different microbial composition of dust observed in these two countries.

Probiotics and the Potential of Genetic Modification as a Possible Treatment for Food Allergy

Food allergy is a common condition that affects millions of people worldwide. It is caused by an abnormal immune response to harmless food antigens, which is influenced by genetics and environmental factors. Modulating the gut microbiota and immune system with probiotics or genetically modified probiotics confers health benefits to the host and offers a novel strategy for preventing and treating food allergy. This systematic review aims to summarize the current proof of the role of probiotics in food allergy and propose a promising future research direction of using probiotics as a possible strategy of treatment for food allergy.

The First 1000 Days of Life: How Changes in the Microbiota Can Influence Food Allergy Onset in Children

BACKGROUND

Allergic disease, including food allergies (FA)s, has been identified as a major global disease. The first 1000 days of life can be a "window of opportunity" or a "window of susceptibility", during which several factors can predispose children to FA development. Changes in the composition of the gut microbiota from pregnancy to infancy may play a pivotal role in this regard: some bacterial genera, such as Lactobacillus and Bifidobacterium, seem to be protective against FA development. On the contrary, Clostridium and Staphylococcus appear to be unprotective.

METHODS

We conducted research on the most recent literature (2013-2023) using the PubMed and Scopus databases. We included original papers, clinical trials, meta-analyses, and reviews in English. Case reports, series, and letters were excluded.

RESULTS

During pregnancy, the maternal diet can play a fundamental role in influencing the gut microbiota composition of newborns. After birth, human milk can promote the development of protective microbial species via human milk oligosaccharides (HMOs), which play a prebiotic role. Moreover, complementary feeding can modify the gut microbiota's composition.

CONCLUSIONS

The first two years of life are a critical period, during which several factors can increase the risk of FA development in genetically predisposed children.

Relationship between Gut Microbiota and Allergies in Children: A Literature Review

The intestinal microbiota is a diverse and complex microecosystem that lives and thrives within the human body. The microbiota stabilizes by the age of three. This microecosystem plays a crucial role in human health, particularly in the early years of life. Dysbiosis has been linked to the development of various allergic diseases with potential long-term implications. Next-generation sequencing methods have established that allergic diseases are associated with dysbiosis. These methods can help to improve the knowledge of the relationship between dysbiosis and allergic diseases. The aim of this review paper is to synthesize the current understanding on the development of the intestinal microbiota in children, the long-term impact on health, and the relationship between dysbiosis and allergic diseases. Furthermore, we examine the connection between the microbiome and specific allergies such as atopic dermatitis, asthma, and food allergies, and which mechanisms could determine the induction of these diseases. Furthermore, we will review how factors such as mode of delivery, antibiotic use, breastfeeding, and the environment influence the development of the intestinal flora, as well as review various interventions for the prevention and treatment of gut microbiota-related allergies.

A Review on Maternal and Infant Microbiota and Their Implications for the Prevention and Treatment of Allergic Diseases

Allergic diseases, which are closely related to the composition and metabolism of maternal and infant flora, are prevalent in infants worldwide. The mother's breast milk, intestinal, and vaginal flora directly or indirectly influence the development of the infant's immune system from pregnancy to lactation, and the compositional and functional alterations of maternal flora are associated with allergic diseases in infants. Meanwhile, the infant's own flora, represented by the intestinal flora, indicates and regulates the occurrence of allergic diseases and is altered with the intervention of allergic diseases. By searching and selecting relevant literature in PubMed from 2010 to 2023, the mechanisms of allergy development in infants and the links between maternal and infant flora and infant allergic diseases are reviewed, including the effects of flora composition and its consequences on infant metabolism. The critical role of maternal and infant flora in allergic diseases has provided a window for probiotics as a microbial therapy. Therefore, the uses and mechanisms by which probiotics, such as lactic acid bacteria, can help to improve the homeostasis of both the mother and the infant, and thereby treat allergies, are also described.

Microbial transmission, colonisation and succession: from pregnancy to infancy

The microbiome has been proven to be associated with many diseases and has been used as a biomarker and target in disease prevention and intervention. Currently, the vital role of the microbiome in pregnant women and newborns is increasingly emphasised. In this review, we discuss the interplay of the microbiome and the corresponding immune mechanism between mothers and their offspring during the perinatal period. We aim to present a comprehensive picture of microbial transmission and potential immune imprinting before and after delivery. In addition, we discuss the possibility of in utero microbial colonisation during pregnancy, which has been highly debated in recent studies, and highlight the importance of the microbiome in infant development during the first 3 years of life. This holistic view of the role of the microbial interplay between mothers and infants will refine our current understanding of pregnancy complications as well as diseases in early life and will greatly facilitate the microbiome-based prenatal diagnosis and treatment of mother-infant-related diseases.

Butyrate in Human Milk: Associations with Milk Microbiota, Milk Intake Volume, and Infant Growth

Butyrate in human milk (HM) has been suggested to reduce excessive weight and adipo-sity gains during infancy. However, HM butyrate's origins, determinants, and its influencing mechanism on weight gain are not completely understood. These were studied in the prospective longitudinal Cambridge Baby Growth and Breastfeeding Study (CBGS-BF), in which infants (n = 59) were exclusively breastfed for at least 6 weeks. Infant growth (birth, 2 weeks, 6 weeks, 3 months, 6 months, and 12 months) and HM butyrate concentrations (2 weeks, 6 weeks, 3 months, and 6 months) were measured. At age 6 weeks, HM intake volume was measured by deuterium-labelled water technique and HM microbiota by 16S sequencing. Cross-sectionally at 6 weeks, HM butyrate was associated with HM microbiota composition (p = 0.036) although no association with the abundance of typical butyrate producers was detected. In longitudinal analyses across all time points, HM butyrate concentrations were overall negatively associated with infant weight and adiposity, and associations were stronger at younger infant ages. HM butyrate concentration was also inversely correlated with HM intake volume, supporting a possible mechanism whereby butyrate might reduce infant growth via appetite regulation and modulation of HM intake.

Functional effects of human milk oligosaccharides (HMOs)

Human milk oligosaccharides (HMOs) are the third most important solid component in human milk and act in tandem with other bioactive components. Individual HMO levels and distribution vary greatly between mothers by multiple variables, such as secretor status, race, geographic region, environmental conditions, season, maternal diet, and weight, gestational age and mode of delivery. HMOs improve the gastrointestinal barrier and also promote a bifidobacterium-rich gut microbiome, which protects against infection, strengthens the epithelial barrier, and creates immunomodulatory metabolites. HMOs fulfil a variety of physiologic functions including potential support to the immune system, brain development, and cognitive function. Supplementing infant formula with HMOs is safe and promotes a healthy development of the infant revealing benefits for microbiota composition and infection prevention. Because of limited data comparing the effect of non-human oligosaccharides to HMOs, it is not known if HMOs offer an additional clinical benefit over non-human oligosaccharides. Better knowledge of the factors influencing HMO composition and their functions will help to understand their short- and long-term benefits.

The effects of elemene emulsion injection on rat fecal microbiota and metabolites: Evidence from metagenomic exploration and liquid chromatography-mass spectrometry

Objective

Elemene emulsion injection (EEI) has been approved for interventional and intracavitary chemotherapy in treating malignant ascites in China, but few studies have focused on the effects of EEI on gut microbiota and metabolites. In this study, we investigated the effects of EEI on the fecal microbiota and metabolites in healthy Sprague-Dawley (SD) rats.

Methods

We randomly assigned 18 male SD rats to three groups (n = 6 in each group): the sham group (group S), the low-concentration EEI group (L-EEI), and the high-concentration EEI group (H-EEI). The L-EEI and H-EEI rats were administered 14 days of consecutive EEI, 20 mg/kg, and 40 mg/kg intraperitoneally (IP). Group S rats were administered the same volume of normal saline. On day 14, each animal's feces were collected for metagenomic sequencing and metabolomic analysis, and the colonic contents were collected for 16S rRNA sequencing.

Results

EEI could alter the β-diversity but not the α-diversity of the fecal microbiota and induce structural changes in the fecal microbiota. Different concentrations of EEI affect the fecal microbiota differently. The effects of different EEI concentrations on the top 20 bacteria with significant differences at the species level among the three groups were roughly divided into three categories: (1) A positive or negative correlation with the different EEI concentrations. The abundance of Ileibacterium Valens increased as the EEI concentration increased, while the abundance of Firmicutes bacteria and Clostridium sp. CAC: 273 decreased. (2) The microbiota showed a tendency to increase first, then decrease or decrease first, and then increase as EEI concentration increased-the abundance of Prevotella sp. PCHR, Escherichia coli, and Candidatus Amulumruptor caecigallinarius tended to decrease with L-EEI but significantly increased with H-EEI. In contrast, L-EEI significantly increased Ruminococcus bromii and Dorea sp. 5-2 abundance, and Oscillibacter sp. 1-3 abundance tended to increase, while H-EEI significantly decreased them. (3) L-EEI and H-EEI decreased the abundance of bacteria (Ruminococcaceae bacterium, Romboutsia ilealis, and Staphylococcus xylosus). Fecal metabolites, like microbiota, were sensitive to different EEI concentrations and correlated with fecal microbiota and potential biomarkers.

Conclusion

This study shows that intraperitoneal EEI modulates the composition of rat fecal microbiota and metabolites, particularly the gut microbiota's sensitivity to different concentrations of EEI. The impact of changes in the microbiota on human health remains unknown, particularly EEI's efficacy in treating tumors.

Microbial regulation of offspring diseases mediated by maternal-associated microbial metabolites

The microbiota plays a crucial role in individuals’ early and long-term health. Previous studies indicated that the microbial regulation of health may start before birth. As the in utero environment is (nearly) sterile, the regulation is probably be originated from maternal microbiota and mediated by their metabolites transferred across the placenta. After the birth, various metabolites are continuously delivered to offspring through human milk feeding. Meanwhile, some components, for example, human milk oligosaccharides, in human milk can only be fermented by microbes, which brings beneficial effects on offspring health. Hence, we speculated that human milk-derived metabolites may also play roles in microbial regulation. However, reports between maternal-associated microbial metabolites and offspring diseases are still lacking and sparsely distributed in several fields. Also, the definition of the maternal-associated microbial metabolite is still unclear. Thus, it would be beneficial to comb through the current knowledge of these metabolites related to diseases for assisting our goals of early prediction, early diagnosis, early prevention, or early treatment through actions only on mothers. Therefore, this review aims to present studies showing how researchers came to the path of investigating these metabolites and then to present studies linking them to the development of offspring asthma, type 1 diabetes mellitus, food allergy, neonatal necrotizing enterocolitis, or autism spectrum disorder. Potential English articles were collected from PubMed by searching terms of disease(s), maternal, and a list of microbial metabolites. Articles published within 5 years were preferred.

Nutrition, Gut Microbiota, and Allergy Development in Infants

The process of gut microbiota development in infants is currently being challenged by numerous factors associated with the contemporary lifestyle, including diet. A thorough understanding of all aspects of microbiota development will be necessary for engineering strategies that can modulate it in a beneficial direction. The long-term consequences for human development and health of alterations in the succession pattern that forms the gut microbiota are just beginning to be explored and require much further investigation. Nevertheless, it is clear that gut microbiota development in infancy bears strong associations with the risk for allergic disease. A useful understanding of microbial succession in the gut of infants needs to reveal not only changes in taxonomic composition but also the development of functional capacities through time and how these are related to diet and various environmental factors. Metagenomic and metatranscriptomic studies have started to produce insights into the trends of functional repertoire and gene expression change within the first year after birth. This understanding is critical as during this period the most substantial development of the gut microbiota takes place and the relations between gut microbes and host immunity are established. However, further research needs to focus on the impact of diet on these changes and on how diet can be used to counteract the challenges posed by modern lifestyles to microbiota development and reduce the risk of allergic disease.

Current Use of Probiotics and Prebiotics in Allergy

The microbiome plays an important role in the pathogenesis of allergic diseases. This review updates the reader on studies aimed at influencing allergic diseases through modulation of the gut microflora. A nonsystematic review of the literature was performed, focusing on relevant trials evaluating the effect of probiotics/prebiotics/symbiotics in the prevention and treatment of allergic disease. For each allergic disease, we were able to find not only a substantial number of clinical trials but also systematic reviews. Specific guidelines, based on systematic reviews and meta-analyses, are available for the prevention of allergic disease and for the treatment of food allergy. In each of the areas examined-allergic rhinitis, allergic asthma, atopic dermatitis, food allergy, and gastrointestinal allergies-there are substantial uncertainties in the efficacy of gut microflora modulation in prevention and treatment. At present, practicing clinicians can avail themselves of intestinal flora modulators as an adjunct in the prevention of atopic dermatitis but not of other forms of allergic diseases. Their effects on the treatment of allergic diseases remain controversial.

The Role of Early Life Microbiota Composition in the Development of Allergic Diseases

Allergic diseases are becoming a major healthcare issue in many developed nations, where living environment and lifestyle are most predominantly distinct. Such differences include urbanized, industrialized living environments, overused hygiene products, antibiotics, stationary lifestyle, and fast-food-based diets, which tend to reduce microbial diversity and lead to impaired immune protection, which further increase the development of allergic diseases. At the same time, studies have also shown that modulating a microbiocidal community can ameliorate allergic symptoms. Therefore, in this paper, we aimed to review recent findings on the potential role of human microbiota in the gastrointestinal tract, surface of skin, and respiratory tract in the development of allergic diseases. Furthermore, we addressed a potential therapeutic or even preventive strategy for such allergic diseases by modulating human microbial composition.

Microbial Dysbiosis Tunes the Immune Response Towards Allergic Disease Outcomes

The hygiene hypothesis has been popularized as an explanation for the rapid increase in allergic disease observed over the past 50 years. Subsequent epidemiological studies have described the protective effects that in utero and early life exposures to an environment high in microbial diversity have in conferring protective benefits against the development of allergic diseases. The rapid advancement in next generation sequencing technology has allowed for analysis of the diverse nature of microbial communities present in the barrier organs and a determination of their role in the induction of allergic disease. Here, we discuss the recent literature describing how colonization of barrier organs during early life by the microbiota influences the development of the adaptive immune system. In parallel, mechanistic studies have delivered insight into the pathogenesis of disease, by demonstrating the comparative effects of protective T regulatory (Treg) cells, with inflammatory T helper 2 (Th2) cells in the development of immune tolerance or induction of an allergic response. More recently, a significant advancement in our understanding into how interactions between the adaptive immune system and microbially derived factors play a central role in the development of allergic disease has emerged. Providing a deeper understanding of the symbiotic relationship between our microbiome and immune system, which explains key observations made by the hygiene hypothesis. By studying how perturbations that drive dysbiosis of the microbiome can cause allergic disease, we stand to benefit by delineating the protective versus pathogenic aspects of human interactions with our microbial companions, allowing us to better harness the use of microbial agents in the design of novel prophylactic and therapeutic strategies.