Mother's Milk Microbiome Shaping Fecal and Skin Microbiota in Infants with Food Allergy and Atopic Dermatitis: A Pilot Analysis

Maternal Gut Inflammation Aggravates Acute Liver Failure Through Facilitating Ferroptosis via Altering Gut Microbial Metabolism in Offspring

Microbial transmission from mother to infant is important for offspring microbiome formation and health. However, it is unclear whether maternal gut inflammation (MGI) during lactation influences mother-to-infant microbial transmission and offspring microbiota and disease susceptibility. In this study, it is found that MGI during lactation altered the gut microbiota of suckling pups by shaping the maternal microbiota in the gut and mammary glands. MGI-induced changes in the gut microbiota of suckling pups lasted into adulthood, resulting in the exacerbation of acute liver failure (ALF) caused by acetaminophen (APAP) in offspring. Specifically, MGI reduced the abundance of Lactobacillus reuteri (L. reuteri) and its metabolite indole-3-acetic acid (IAA) level in adult offspring. L. reuteri and IAA alleviated ALF in mice by promoting intestinal IL-22 production. Mechanistically, IL-22 limits APAP-induced excessive oxidative stress and ferroptosis by activating STAT3. The intestinal abundances of L. reuteri and IAA are inversely associated with the progression of patients with ALF. Overall, the study reveals the role of MGI in mother-to-infant microbial transmission and disease development in offspring, highlighting potential strategies for intervention in ALF based on the IAA-IL-22-STAT3 axis.

Gut-X axis

Recent advances in understanding the modulatory functions of gut and gut microbiota on human diseases facilitated our focused attention on the contribution of the gut to the pathophysiological alterations of many extraintestinal organs, including the liver, heart, brain, lungs, kidneys, bone, skin, reproductive, and endocrine systems. In this review, we applied the "gut-X axis" concept to describe the linkages between the gut and other organs and discussed the latest findings related to the "gut-X axis," including the underlying modulatory mechanisms and potential clinical intervention strategies.

Nurturing development: how a mother's nutrition shapes offspring's brain through the gut

Pregnancy is a transformative period marked by profound physical and emotional changes, with far-reaching consequences for both mother and child. Emerging research has illustrated the pivotal role of a mother's diet during pregnancy in influencing the prenatal gut microbiome and subsequently shaping the neurodevelopment of her offspring. The intricate interplay between maternal gut health, nutrition, and neurodevelopmental outcomes has emerged as a captivating field of investigation within developmental science. Acting as a dynamic bridge between mother and fetus, the maternal gut microbiome, directly and indirectly, impacts the offspring's neurodevelopment through diverse pathways. This comprehensive review delves into a spectrum of studies, clarifying putative mechanisms through which maternal nutrition, by modulating the gut microbiota, orchestrates the early stages of brain development. Drawing insights from animal models and human cohorts, this work underscores the profound implications of maternal gut health for neurodevelopmental trajectories and offers a glimpse into the formulation of targeted interventions able to optimize the health of both mother and offspring. The prospect of tailored dietary recommendations for expectant mothers emerges as a promising and accessible intervention to foster the growth of beneficial gut bacteria, potentially leading to enhanced cognitive outcomes and reduced risks of neurodevelopmental disorders.

Atopic dermatitis and food allergy: More than sensitization

The increased risk of food allergy in infants with atopic dermatitis (AD) has long been recognized; an epidemiologic phenomenon termed "the atopic march." Current literature supports the hypothesis that food antigen exposure through the disrupted skin barrier in AD leads to food antigen-specific immunoglobulin E production and food sensitization. However, there is growing evidence that inflammation in the skin drives intestinal remodeling via circulating inflammatory signals, microbiome alterations, metabolites, and the nervous system. We explore how this skin-gut axis helps to explain the link between AD and food allergy beyond sensitization.

The Role of the Microbiota in the Pathogenesis and Treatment of Atopic Dermatitis-A Literature Review

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a high prevalence worldwide. AD pathogenesis is complex and consists of immune system dysregulation and impaired skin barrier, influenced by genetic and environmental factors. The purpose of the review is to show the complex interplay between atopic dermatitis and the microbiota. Human microbiota plays an important role in AD pathogenesis and the course of the disease. Dysbiosis is an important factor contributing to the development of atopic diseases, including atopic dermatitis. The gut microbiota can influence the composition of the skin microbiota, strengthening the skin barrier and regulating the immune response via the involvement of bacterial metabolites, particularly short-chain fatty acids, in signaling pathways of the gut-skin axis. AD can be modulated by antibiotic intake, dietary adjustments, hygiene, and living conditions. One of the promising strategies for modulating the course of AD is probiotics. This review offers a summary of how the microbiota influences the development and treatment of AD, highlighting aspects that warrant additional investigation.

Microbiome: Mammalian milk microbiomes: sources of diversity, potential functions, and future research directions

Abstract

Milk is an ancient, fundamental mammalian adaptation that provides nutrition and biochemical communication to offspring. Microbiomes have been detected in milk of all species studied to date. In this review, we discuss: (a) routes by which microbes may enter milk; (b) evidence for proposed milk microbiome adaptive functions; (c) variation in milk microbiomes across mammals; and (d) future research directions, including suggestions for how to address outstanding questions on the viability and functionality of milk microbiomes. Milk microbes may be sourced from the maternal gastrointestinal tract, oral, skin, and mammary gland microbiomes and from neonatal oral and skin microbiomes. Given the variety of microbial sources, stochastic processes strongly influence milk microbiome assembly, but milk microbiomes appear to be influenced by maternal evolutionary history, diet, environment, and milk nutrients. Milk microbes have been proposed to colonize the neonatal intestinal tract and produce gene and metabolic products that influence physiology, metabolism, and immune system development. Limited epidemiological data indicate that early-life exposure to milk microbes can result in positive, long-term health outcomes. Milk microbiomes can be modified by dietary changes including providing the mother with probiotics and prebiotics. Milk replacers (i.e. infant formula) may benefit from supplementation with probiotics and prebiotics, but data are lacking on probiotics' usefulness, and supplementation should be evidence based. Overall, milk microbiome literature outside of human and model systems is scarce. We highlight the need for mechanistic studies in model species paired with comparative studies across mammals to further our understanding of mammalian milk microbiome evolution. A broader study of milk microbiomes has the potential to inform animal care with relevance to ex situ endangered species.

Lay summary

Milk is an ancient adaptation that supports the growth and development of mammalian neonates and infants. Beyond its fundamental nutritional function, milk influences all aspects of neonatal development, especially immune function. All kinds of milks so far studied have contained a milk microbiome. In this review, we focus on what is known about the collection of bacterial members found in milk microbiomes. Milk microbiomes include members sourced from maternal and infant microbiomes and they appear to be influenced by maternal evolutionary history, diet, milk nutrients, and environment, as well as by random chance. Once a neonate begins nursing, microbes from milk colonize their gut and produce byproducts that influence their physiology, metabolism, and immune development. Empirical data on milk microbiomes outside of humans and model systems are sparse. Greater study of milk microbiomes across mammals will expand our understanding of mammalian evolution and improve the health of animals under human care.

A Retrospective Analysis of Risk Factors for Atopic Dermatitis Severity

Background: Atopic dermatitis (AD) has the highest burden of any skin disease; however, the severity-associated factors remain unclear. Objective: To evaluate potential severity-associated factors of AD and to design and validate a severity prediction model to inform the management of AD patients. Methods: A cross-sectional study of 900 AD patients was conducted from December 2021 to October 2022 at our hospital. The primary outcome was disease severity, categorized as mild, moderate, or severe using the scoring atopic dermatitis index. Ordinal logistic regression and bootstrapped validation were used to derive and internally validate the model. Results: Increasing age, elevated eosinophil level, higher economic status, and urban residence were associated with severe AD. Breastfeeding, disinfectants and topical emollients use, and short duration of bathing were associated with mild AD. In the prediction model, predictors included age, eosinophil and economic status, residence, feeding, disinfectants and emollients use, and duration of bathing. Prediction models demonstrated good discrimination (bias-corrected concordance index [c-index] = 0.72) and good calibration. Conclusion: Risk factors for the severity of AD were identified that could aid the early prediction of AD progression. The predictive model included variables that are easily evaluated and could inform personalized prevention and therapy.

Lipidomics and Metabolomics in Infant Atopic Dermatitis: What's the Correlation with Early Nutrition?

To date, the complex picture of atopic dermatitis (AD) has not yet been fully clarified, despite the important prevalence of this disease in the pediatric population (20%) and the possibility of persistence into adulthood, with important implications for the quality of life of those affected, as well as significant social and financial costs. The most recent scientific evidence suggests a new interpretation of AD, highlighting the important role of the environment, particularly that of nutrition in the early stages of development. In fact, the new indications seem to point out the harmful effect of elimination diets, except in rare cases, the uselessness of chrono-insertions during complementary feeding and some benefits, albeit weak, of breastfeeding in those at greater risk. In this context, metabolomics and lipidomics can be necessary for a more in-depth knowledge of the complex metabolic network underlying this pathology. In fact, an alteration of the metabolic contents in children with AD has been highlighted, especially in correlation to the intestinal microbiota. While preliminary lipidomic studies showed the usefulness of a more in-depth knowledge of the alterations of the skin barrier to improve the development of baby skin care products. Therefore, investigating the response of different allergic phenotypes could be useful for better patient management and understanding, thus providing an early intervention on dysbiosis necessary to regulate the immune response from the earliest stages of development.

An update on the current understanding of the infant skin microbiome and research challenges

Multiple factors contribute to establishment of skin microbial communities in early life, with perturbations in these ecosystems impacting health. This review provides an update on methods used to profile the skin microbiome and how this is helping enhance our understanding of infant skin microbial communities, including factors that influence composition and disease risk. We also provide insights into new interventional studies and treatments in this area. However, it is apparent that there are still research bottlenecks that include overreliance on high-income countries for skin microbiome 'surveys', many studies still focus solely on the bacterial microbiota, and also technical issues related to the lower microbial biomass of skin sites. These points link to pertinent open-research questions, such as how the whole infant skin microbiome interacts and how microbial-associated functions shape infant skin health and immunity.

The skin microbiome in the first year of life and its association with atopic dermatitis

BACKGROUND

Early-life microbial colonization of the skin may modulate the immune system and impact the development of atopic dermatitis (AD) and allergic diseases later in life. To address this question, we assessed the association between the skin microbiome and AD, skin barrier integrity and allergic diseases in the first year of life. We further explored the evolution of the skin microbiome with age and its possible determinants, including delivery mode.

METHODS

Skin microbiome was sampled from the lateral upper arm on the first day of life, and at 3, 6, and 12 months of age. Bacterial communities were assessed by 16S rRNA gene amplicon sequencing in 346 infants from the PreventADALL population-based birth cohort study, representing 970 samples. Clinical investigations included skin examination and skin barrier function measured as trans-epidermal water loss (TEWL) at the site and time of microbiome sampling at 3, 6, and 12 months. Parental background information was recorded in electronic questionnaires, and delivery mode (including vaginal delivery (VD), VD in water, elective caesarean section (CS) and emergency CS) was obtained from maternal hospital charts.

RESULTS

Strong temporal variations in skin bacterial community composition were found in the first year of life, with distinct patterns associated with different ages. Confirming our hypothesis, skin bacterial community composition in the first year of life was associated with skin barrier integrity and later onsets of AD. Delivery mode had a strong impact on the microbiome composition at birth, with each mode leading to distinct patterns of colonization. Other possible determinants of the skin microbiome were identified, including environmental and parental factors as well as breastfeeding.

CONCLUSION

Skin microbiome composition during infancy is defined by age, transiently influenced by delivery mode as well as environmental, parental factors and breastfeeding. The microbiome is also associated with skin barrier integrity and the onset of AD.

Compositional Variations between Adult and Infant Skin Microbiome: An Update

Human skin and its commensal microbiome form the first layer of protection to the outside world. A dynamic microbial ecosystem of bacteria, fungi and viruses, with the potential to respond to external insult, the skin microbiome has been shown to evolve over the life course with an alteration in taxonomic composition responding to altered microenvironmental conditions on human skin. This work sought to investigate the taxonomic, diversity and functional differences between infant and adult leg skin microbiomes. A 16S rRNA gene-based metataxonomic analysis revealed significant differences between the infant and adult skin groups, highlighting differential microbiome profiles at both the genus and species level. Diversity analysis reveals differences in the overall community structure and associated differential predicted functional profiles between the infant and adult skin microbiome suggest differing metabolic processes are present between the groups. These data add to the available information on the dynamic nature of skin microbiome during the life course and highlight the predicted differential microbial metabolic process that exists on infant and adult skin, which may have an impact on the future design and use of cosmetic products that are produced to work in consort with the skin microbiome.

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.

Fecal microbiota transplantation affects the recovery of AD-skin lesions and enhances gut microbiota homeostasis

BACKGROUND

Accumulating evidence has shown that gut microbiota plays a key role in the progression of atopic dermatitis (AD). Fecal microbiota transplantation (FMT), as an effective method to restore gut microbiota homeostasis, has been successfully applied for treating many inflammatory diseases. However, the therapeutic effect of FMT on AD remains unclear. The following study examined the effect and mechanism of FMT on AD-skin lesions in an AD mouse model.

METHODS

In this study, we exposed the shaved back skin of BALB/c mice to calcipotriol (MC903) to induce AD model. Mice were then treated with FMT, which was performed with gut microbiota from healthy mice. The gut microbiota of treated mice was tracked by 16S rRNA gene sequencing. Mice skin tissues were examined by histopathology and inflammatory cytokines change in serum by ELISA.

RESULTS

FMT had a faster trend on the reversion of the increases in skin epidermal layer thicknesses and suppressed some of the representative inflammatory cytokines. The gut microbial community in the natural recovery process varied significantly in the FMT group at day 7 (ANOSIM P = 0.0229, r = 0.2593). Notably, FMT had a long-lasting and beneficial impact on the gut microbial compositions of AD mice by increasing the ratio of Firmicutes to Bacteroidetes and the amount of butyric-producing bacteria (BPB), including Erysipelotrichaceae, Lactobacillaceae, and Eubacteriacea. Furthermore, the relative abundances of gut microbiota-mediated functional pathways involved in the cell growth and death, amino acid, energy, lipid, and carbohydrate metabolisms, and immune system increased after FMT treatment.

CONCLUSION

FMT modulated the gut microbiota homeostasis and affected the recovery from AD-related inflammations, suggesting that it could be used as a treatment strategy for AD patients in the clinic.

Skin barrier immunology from early life to adulthood

Our skin has a unique barrier function, which is imperative for the body's protection against external pathogens and environmental insults. Although interacting closely and sharing many similarities with key mucosal barrier sites, such as the gut and the lung, the skin also provides protection for internal tissues and organs and has a distinct lipid and chemical composition. Skin immunity develops over time and is influenced by a multiplicity of different factors, including lifestyle, genetics, and environmental exposures. Alterations in early life skin immune and structural development may have long-term consequences for skin health. In this review, we summarize the current knowledge on cutaneous barrier and immune development from early life to adulthood, with an overview of skin physiology and immune responses. We specifically highlight the influence of the skin microenvironment and other host intrinsic, host extrinsic (e.g. skin microbiome), and environmental factors on early life cutaneous immunity.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

The Environmental Microbiome, Allergic Disease, and Asthma

The environmental microbiome represents the entirety of the microbes and their metabolites that we encounter in our environments. A growing body of evidence supports the role of the environmental microbiome in risk for and severity of allergic diseases and asthma. The environmental microbiome represents a ubiquitous, lifelong exposure to non-self antigens. During the critical window between birth and 1 year of life, interactions between our early immune system and the environmental microbiome have 2 consequences: our individual microbiome is populated by environmental microbes, and our immune system is trained regarding which antigens to tolerate. During this time, a diversity of exposures appears largely protective, dramatically decreasing the risk of developing allergic diseases and asthma. As we grow older, our interactions with the environmental microbiome change. While it continues to exert influence over the composition of the human microbiome, the environmental microbiome becomes increasingly a source for antigenic stimulation and infection. The same microbial exposure protective against disease development may exacerbate disease severity. Although much has been learned about the importance of the environmental microbiome in allergic disease, much more remains to be understood about these complicated interactions between our environment, our microbiome, our immune system, and disease.

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.

Gut microbiota and atopic dermatitis in children: a scoping review

BACKGROUND

Gut microbiota plays an important role in the development of atopic dermatitis (AD). We aimed to elucidate research trends in gut microbiota and AD in children, to provide evidence and insights to the clinical prevention and treatment of AD in children.

METHODS

A scoping literature review on the studies of gut microbiota and AD were conducted. Two authors independently searched Pubmed et al. databases for studies focused on gut microbiota and AD in children up to January 15, 2022. The literatures were screened and analyzed by two reviewers.

RESULTS

A total of 44 reports were finally included and analyzed. Current researches have indicated that abnormal human microecology is closely associated with AD, and the disturbance of intestinal microbiota plays an important role in the occurrence and development of AD. Probiotics can correct the microbiota disorder, have the functions of regulating immunity, antioxidant, and help to restore the microecological homeostasis. However, there is still a lack of high-quality research reports on the efficacy and safety of probiotics in the prevention and treatment of AD in children.

CONCLUSIONS

The changes of gut microbiota are essential to the development of AD in children, which may be an effective target for the prevention and treatment of AD. Future studies with larger sample size and rigorous design are needed to elucidate the effects and safety of probiotics in AD.