The Science, Microbes & Health Podcast

A mechanism linking the newborn skin microbiota to neurodevelopment, with Prof. Rihua Xie and Dr. Yuhang Zhang

This episode features Prof. Rihua Xie from Guangdong Medical University (China) and Dr. Yuhang Zhang from Peking University First Hospital (China), speaking about vaginal microbiota transfer (VMT) and how it may affect neurodevelopment in newborn infants born by Cesarean section. Compared with vaginally delivered infants, C-section delivered infants have altered microbial exposures. VMT has been proposed as a way to ‘restore’ the microbiota of these infants to more closely resemble that of vaginally-born infants. A recent study by Prof. Xie and Dr. Zhang showed that the order and timing of early microbial colonization of the infant is important. They found that VMT could establish a vaginal-like skin microbiota in infants born by C-section, with two particular bacterial species that were higher after VMT. These two species led to the production of metabolites that combined on the newborn’s skin to synthesize an important lipid, which was positively correlated with neurodevelopment scores at three and six months. Subsequent mouse model work showed how this lipid could reach the brain. In the future, safety and standardization of VMT will be important priorities in this research area. Prof. Xie and Dr. Zhang emphasized that their work needs to be replicated in larger cohorts, with the eventual goal of engineering bacteria to create a probiotic intervention that delivers neurodevelopmental benefits to C-section born infants. EPISODE ABBREVIATIONS AND LINKS: * The research by Prof. Xie and Dr. Zhang demonstrating how a VMT intervention alters the skin microbiota of newborns, with a mechanistic link to neurodevelopment: Vaginal microbiota transfer ameliorates cesarean-associated neurodevelopmental deficits in mice via N-bc2S1P synthesis on neonatal skin [https://www.sciencedirect.com/science/article/abs/pii/S1931312826001319] ABOUT PROF. RIHUA XIE: Dr. Ri-hua Xie (RN, PhD, FAAN) is Professor, Principal Investigator, and Chief Nurse at the School of Nursing, Southern Medical University, and the Affiliated Foshan Women and Children Hospital, Guangdong Medical University, China. Dr. Xie is widely recognized for her expertise in maternal and infant health as a clinician, researcher, and supervisor. She has published more than 90 peer-reviewed papers and 11 nursing textbooks and has received 12 competitive research grants from institutions in China and Canada. In addition to her academic work, Dr. Xie is actively engaged in community and public health service, including breastfeeding promotion and frontline support during the COVID-19 pandemic. Her research focuses on perinatal epidemiology, maternal and child health, and microbiome science, with a particular emphasis on the effects of vaginal microbiota transfer (VMT) on the microbiota composition and health outcomes of cesarean-delivered infants. ABOUT DR. YUHANG ZHANG: Yuhang Zhang, PhD in Pharmacology, is an Associate Professor and Principal Investigator at Peking University First Hospital. He received his MD-PhD from Capital Medical University and was a visiting scholar at McGill University, Canada. Dr. Zhang’s research focuses on gut microbiome, probiotics, and microbial metabolism in metabolic diseases, who has published over 20 peer‑reviewed papers as first or corresponding author in journals including Gastroenterology, Journal of Hepatology, and Nature Communications, cited >1,000 times. He has led 9 grants, including the National Natural Science Foundation of China, who was selected for the Beijing Association for Science and Technology Young Talent Program (2022) and the China Association for Science and Technology Young Talent Program (2025). The research of Dr. Zhang focuses on the integrated systems pharmacology, multiomics and microbiome‑host interactions to develop precision medicine.

Gut microbiota development in preterm and non-preterm infants, with Dr. Marie-Claire Arrieta PhD

This episode features Dr. Marie-Claire Arrieta PhD from the University of Calgary (Canada), speaking about development of the early life gut microbiome, both in preterm and non-preterm infants. Across the field, it has been established that the early days and months of an infant’s life are very determinant of immune system development as well as chronic disease later in life. In this period, environmental cues are important, with some of these cues coming from the gut microbiome – both bacteria and fungi. Preterm infants show a very different gut microbiome than non-preterm infants. Ample evidence shows probiotics given to preterm infants can bring clinical benefits such as a reduced risk of necrotizing enterocolitis, but this is separate from investigations into the infants’ gut microbiomes. Dr. Arrieta’s work has shown that probiotics can guide the gut ecosystem of preterm infants toward approximating the non-preterm gut microbiome. One gap in the research is to know more about the effects of specific strains; their work found that although bifidobacteria were more effective at colonizing in the gut, lactobacilli drove some aspects of microbiota maturation. Dr. Arrieta speculates that the case for probiotic use for preterm infants will become stronger as trials increasingly focus on health outcomes not just during the neonatal intensive care unit stay, but also later in life. Overall in healthy infants, different patterns of gut microbiome and immune development can lead to the appearance of diseases later in life. The latest insight is that disease is linked not to specific microbes or metabolites, but to the pace of gut microbiome development. Misalignment of gut microbiome development (too early or too late) with stages of immune development is associated with later emergence of allergic disease. Several factors such as C-section birth and antibiotics may contribute to this misalignment, but breastfeeding seems to mitigate it. Dr. Arrieta has an ongoing longitudinal study on the early life microbiota and disease associations in preterm and non-preterm infants that is likely to reveal more details. EPISODE ABBREVIATIONS AND LINKS: * Study from Arrieta lab showing effects of a probiotic on the gut microbiome of preterm infants: Supplementation with a probiotic mixture accelerates gut microbiome maturation and reduces intestinal inflammation in extremely preterm infants [https://www.cell.com/cell-host-microbe/fulltext/S1931-3128%2822%2900211-6] * Study combining preterm infant data from several countries, showing links between gut microbiota, immune system development, and late-onset sepsis: Gut microbiota immaturity with DL-endopeptidase deficiency links antibiotic use to preterm late-onset sepsis [https://www.cell.com/cell-host-microbe/fulltext/S1931-3128(26)00049-1] * Arrieta lab website: https://www.arrietalab.com/ [https://www.arrietalab.com/] * Let Them Eat Dirt website with resources for the general public: https://letthemeatdirt.com/ [https://letthemeatdirt.com/] ABOUT DR. MARIE-CLAIRE ARRIETA PHD: Dr. Marie-Claire Arrieta is a Professor and Research Excellence Chair at the Cumming School of Medicine, University of Calgary. Her research examines interactions between the early-life gut microbiome and infant development. Her program integrates clinical and experimental approaches to uncover mechanisms of host–microbiome communication. Her work, published in leading journals, has accumulated over 12,000 citations. She has presented her research internationally through more than 120 invited talks to scientific, medical and public audiences. A dedicated mentor, she has supervised over 45 undergraduate, medical, PhD, and postdoctoral trainees. Her contributions have been recognized with the CIHR-SickKids New Investigator Award, the Killam Emerging Research Leader Award, and election to the College of New Scholars of the Royal Society of Canada. Dr. Arrieta is co-author of the best-selling public book, Let Them Eat Dirt, and is involved in several science communication initiatives.

Toward skin microbiome interventions for anti-aging and wound healing, with Prof. Hariom Yadav PhD

This episode features Prof. Hariom Yadav PhD, from the University of South Florida (USA), speaking about the skin microbiome and potential interventions for anti-aging and wound healing. Prof. Yadav noted that humans have a stable (core) microbiome on the surface of skin cells, plus a transient microbiome that depends on recent exposures. The skin microbiome constantly changes through the lifespan, and in aging, many skin conditions are correlated with the microbiome. Animal studies show a causal component of the microbiome in some of these conditions. However, because of the large skin microbiome differences from person to person and in narrow age groups, technologies or products may have to be designed in a personalized way. Prof. Yadav’s lab conducted experiments with lactobacilli and found strain-dependent effects of probiotics on anti-aging, and for some strains these effects persisted when the inactivated bacteria (postbiotics) were used. The postbiotics have commercial advantages over probiotics in this area of health. Prof. Yadav described an application in wound healing, building on the idea that microbial stimulation promotes natural skin cell growth and more fibroblasts. A standard treatment for wound healing is effective but may lead to scarring; the postbiotic treatment leaves less scarring. The efficacy of the postbiotic occurs because inactivated bacteria still give growth-promoting signals to the skin cells. Applying metabolites directly may not be as effective because bacterial cells or extracts work on host cells, which changes the skin environment and further supports positive skin microbiome changes. Episode abbreviations and links: * Jeffrey Gordon’s landmark paper in 2006: An obesity-associated gut microbiome with increased capacity for energy harvest [https://www.nature.com/articles/nature05414] * Review on the skin microbiome and aging by Prof. Yadav and colleagues: Microbiome-Aging-Wrinkles Axis of Skin: Molecular Insights and Microbial Interventions [https://www.mdpi.com/1422-0067/26/20/10022] * Review on postbiotic skin interventions by Prof. Yadav and colleagues: Microbiome and Postbiotics in Skin Health [https://pmc.ncbi.nlm.nih.gov/articles/PMC12025169/] About Prof. Hariom Yadav PhD: Dr. Hariom Yadav is a Professor at the University of South Florida and Director of the USF Center for Microbiome Research, and co-founder of Postbiotics Inc (www.postbioticsinc.com [http://www.postbioticsinc.com]) and MusB Research (www.musbhealth.com [http://www.musbhealth.com]). With over 25 years of experience, he specializes in microbiome science, biotics, nutrition, longevity, and natural products for optimal wellness. He has authored 200+ peer-reviewed publications, holds/filed 7 patents, mentored over 80 scientists, and has successfully translated multiple innovations into commercially viable products. Dr. Yadav works closely with industry partners to accelerate product development—from discovery and mechanistic validation to clinical trials and regulatory readiness. He leads global collaborative efforts, including the MELLOW (Multi-continental Evidence of Longevity and Lifestyle for Optimal Wellness) consortium, a unique platform for scalable, multi-region clinical validation. His integrated approach enables companies to build scientifically robust, market-ready products with strong differentiation and credibility. He is committed to moving science from bench to market, delivering measurable health impact and commercial success.

Inflammatory microbes on the skin, with Dr. Nathan Archer PhD

This episode features Dr. Nathan Archer PhD from Johns Hopkins Medicine (USA), speaking about the skin microbiome and particular microorganisms that cause inflammation. The skin is a dynamic organ with the main functions of keeping moisture in and keeping the environment out. Overall, the skin environment is not very welcoming to microorganisms but some have adapted to thrive in the low pH environment. His research has found that certain bacteria that are normally considered commensals can become pathogenic when they start producing specific proteases that instigate inflammation on the skin. Acute inflammation that removes a bacterial exposure from the skin is beneficial, but chronic inflammation can be a major problem. Staphylococcus aureus is a bacterium that predominates in many inflammatory skin diseases and benefits from an inflammatory environment and disruption in the skin barrier; in turn, S. aureus is proinflammatory and uses proteases to drive skin inflammation. His lab is interested in understanding the connection between skin microorganisms and the ‘atopic march’ (progression of allergic diseases, including atopic dermatitis, through infancy and childhood). They found that S. aureus on the skin can exacerbate allergic reactions in the lungs, driving hard-to-treat neutrophilic asthma. His group is contributing to several strategies for preventing / treating skin and allergic diseases, including a vaccine for S. aureus; so far, vaccines against this bacterium have not succeeded because S. aureus has so many tools for avoiding human immune responses. However, a multivalent vaccine targeting multiple toxins that affect the immune system is currently being developed and is in Phase 1 clinical trials. Episode abbreviations and links: * Paper on the contribution of microorganisms to normal skin function: Commensal Staphylococcus epidermidis contributes to skin barrier homeostasis by generating protective ceramides [https://www.sciencedirect.com/science/article/pii/S1931312822000403] * Research on the mechanisms of how S. aureus triggers skin inflammation: Staphylococcus aureus proteases trigger eosinophil-mediated skin inflammation [https://www.pnas.org/doi/10.1073/pnas.2309243121] * Study on the mechanisms by which S. aureus causes epithelial barrier damage: Quorum sensing between bacterial species on the skin protects against epidermal injury in atopic dermatitis [https://www.science.org/doi/10.1126/scitranslmed.aat8329] * Review article on how S. aureus contributes to skin inflammation: Staphylococcus aureus Proteases: Orchestrators of Skin Inflammation [https://journals.sagepub.com/doi/abs/10.1089/dna.2024.0134?cf-mal-redirected=true&download=true] * Connection of skin microbes to allergic diseases: Epicutaneous Staphylococcus aureus initiates cross-tissue IL-36R signaling for neutrophilic lung inflammation in a model of the atopic march [https://www.cell.com/cell-reports/fulltext/S2211-1247(25)00825-3] * Treatment approach for atopic dermatitis: Development of a human skin commensal microbe for bacteriotherapy of atopic dermatitis and use in a phase 1 randomized clinical trial [https://www.nature.com/articles/s41591-021-01256-2] About Dr. Nathan Archer PhD: Dr. Nathan Archer is an Associate Professor at the Johns Hopkins School of Medicine Department of Dermatology. Dr. Archer’s research involves uncovering how skin microbes, especially the major human pathogen Staphylococcus aureus, exacerbate inflammatory skin diseases such atopic dermatitis as well as how host immunity protects against bacterial skin infections. His work involves the incorporation of immunological and “omic” approaches with preclinical models and clinical samples to reveal mechanistic insights with translational relevance to human disease. His long-term research goals are to develop novel host-directed therapies for the treatment of inflammatory skin disorders and skin infections. Dr. Archer has received funding from the NIH as well as from foundation and industry sources, including the Dermatology Foundation, LEO Foundation, and Pfizer. He has been an invited speaker at numerous international and national conferences with a focus on dermatology, immunology, and microbiology.

The skin microbiome’s role in atopic dermatitis, with Dr. Maria Teresa García-Romero, MD MPH

This episode features Dr. Maria Teresa García-Romero, MD MPH from the National Institute of Pediatrics in Mexico City, talking about the skin microbiome and how it relates to atopic dermatitis. The skin microbiome varies widely at different sites on the body, but in general, increased diversity is associated with healthy skin. In atopic dermatitis, Staphylococcus aureus becomes abundant and skin microbiome diversity decreases, correlating with inflammatory responses. Treatments have the effect of reducing Staphylococcus aureus. These bacteria are now established to have a role in the pathophysiology of the disease. The caution with antibiotic treatment is that a systematic review and meta-analysis from Dr. García-Romero’s group found Staphylococcus aureus isolates from people with atopic dermatitis had suboptimal susceptibility to commonly used antimicrobials, especially in lower middle-income and upper middle-income countries. Mechanistically, Staphylococcus aureus decrease natural antimicrobial molecules in the skin, stimulate the innate immune response, and likely reduce beneficial bacteria. New treatments are urgently needed because atopic dermatitis is very prevalent (affecting 20-30% of the population), with far-reaching effects in children’s and families’ lives. Two ingested probiotics are commercially available for atopic dermatitis, backed by clinical data, whereas topical probiotic treatments require further research. Episode abbreviations and links: * Paper showing how treatments for atopic dermatitis help the skin microbiome more closely resemble healthy controls: The Skin Microbiome of Patients With Atopic Dermatitis Normalizes Gradually During Treatment [https://pmc.ncbi.nlm.nih.gov/articles/PMC8498027/] * Systematic Review and Meta-Analysis looking at susceptibility of atopic-dermatis associated Staphylococcus aureus to antibiotics in different regions of the world: Global Antimicrobial Susceptibility Patterns of Staphylococcus aureus in Atopic Dermatitis [https://jamanetwork.com/journals/jamadermatology/fullarticle/2823597] About Dr. Maria Teresa García-Romero: Dr. Maria Teresa García-Romero is a medical doctor graduated from Tec de Monterrey School of Medicine, magna cum laude. She has a Specialty in Dermatology and Diploma in Medical Mycology from UNAM, Mexico City. Dr. García-Romero completed a Fellowship in Pediatric Dermatology at the University of Toronto, and a Master’s degree in Public Health and Quantitative methods of research at Harvard University Chan School of Public Health.  She has received meritorious awards including the Mexican Foundation for Health (FUNSALUD), Harvard University Presidential Award, Society for Pediatric Dermatology Fellow Award, among others; and funding for research projects by prestigious international organizations such as MIT (Massachusetts Institute for Technology) seed funds and EB Research Partnership.  She is currently an attending physician in the Dermatology Department of the National Institute of Pediatrics in Mexico City and a member of the National System of Researchers level II. She has more than 150 articles published in national and international magazines, supervised multiple postgraduate theses and has presented in multiple forums worldwide. Dr. García-Romero is a member of the Editorial Committee of JAMA Dermatology, Pediatric Dermatology and other high impact journals. Her research interests include the skin microbiome, atopic dermatitis, vascular anomalies and autoimmune disease.