Ping Hu

Dermatitis in the diapered area (DDA) is the most common skin condition in infants and can cause significant pain and discomfort, leading to disturbed sleep, changes in temperament, and heightened concern and anxiety for caregivers. This study investigates the relationship between skin pH, microbiome composition, and DDA severity in 158 infants from China, the US, and Germany, focusing on the buttocks, perianal, and thigh regions. Significant variations in DNA biomass and microbiota profiles were noted. Escherichia coli and Veillonella atypica were linked to higher rash scores and elevated skin pH, while Bifidobacterium longum showed a negative correlation with buttocks pH and rash severity but not with perianal rash. Correlation patterns emerged for other species, like Enterococcus faecalis, between perianal and buttocks rashes. Functional analysis identified key categories, including lipid and fatty acid metabolism, cofactor, amino acid, and carbohydrate metabolism, homeostasis and osmolarity stress, and microbial virulence and oxidative stress response, which are vital for skin health, DDA, and pH regulation in infants. These findings underscore the importance of maintaining a mildly acidic skin pH and minimizing fecal and urine residues for optimal infant skin health, suggesting that microbiota significantly influence DDA development, and provide insights for future preventive strategies and therapeutic interventions.

This research examined the effects of daily application of an oral hygiene regimen on the subgingival microbiome over 24 months. Generally healthy adults (107 enrolled, 87 completed) with early periodontitis used a home-care regimen (stannous fluoride paste, cetylpyridinium chloride rinse, power toothbrush, and floss) or usual care (control). Subgingival plaque samples were analyzed enzymatically for bacterial toxins. TLR ligands were measured using TLR-SEAP and TLR-ATP assays. Proinflammatory cytokines and metalloproteinases were quantified via immunoassays. Subgingival DNA was sequenced using a shotgun approach to assess microbial diversity. Increasing levels of bacteria, toxins, TLR activation, inflammatory cytokines, and MMPs were observed for periodontitis versus gingivitis and gingivitis versus healthy sites. The regimen significantly reduced levels of the critical proinflammatory cytokine IL-1β, as well as MMP-1 and MMP-9, at 24 months. By month 6, TLR ligands within subgingival plaques decreased. The abundance of pathogenic bacteria correlated with levels of virulence factors, proinflammatory cytokines, MMPs, and severity of clinical measures. Two distinct constellations of pathogenic bacteria were identified. Gingival sites were categorized into responders and non-responders per clinical symptoms and biomarkers. The regimen yielded more responder sites (70%) versus the control (47%), p = 0.0002914. The regimen reduced pathogenic bacteria, IL-1β, MMP1, and MMP-9, paralleling clinical reductions in periodontal disease.

Poor oral health is a neglected epidemic, potentially contributing to systemic health issues. We employed a multi-omics approach to investigate the biological changes associated with gingivitis and the effects of stannous fluoride (SnF₂) dentifrice on microbial composition and salivary proteomics in an eight-week clinical trial involving 39 participants categorized as high (n = 20) and low bleeders (n = 19). Baseline assessments revealed significant microbial dysbiosis in high bleeders, characterized by a higher abundance of Porphyromonas and Fusobacterium, alongside compromised epithelial barriers and increased inflammation. Following SnF₂ treatment, a substantial reduction in these bacteria, and an increase in Rothia and Haemophulis, were observed, correlating with improved clinical measures, including reduced bleeding and inflammation indices. In total, 80 proteins (including pro-inflammatory cytokines, alarmin keratins, and matrix metalloproteinases) showed a significant reduction in high bleeders after treatment, with 29 overlapping the disease biomarkers in the plasma atlas, supporting the role of SnF₂ in mitigating oxidative stress and enhancing epithelial integrity. Furthermore, SnF₂ treatment significantly reduced collagen degradation, suggesting the preservation of tissue integrity. These findings highlight that SnF₂ not only improves local oral health but may also benefit systemic health, showcasing the value of a multi-omics approach in understanding the interconnections among oral microbiota, inflammatory responses, and systemic health outcomes.

Various ingredients are utilized to inhibit the growth of harmful bacteria associated with cavities, gum disease, and bad breath. However, the precise mechanisms by which these ingredients affect the oral microbiome have not been fully understood at the molecular level. To elucidate the molecular mechanisms, a high-throughput bacterial transcriptomics study was conducted, and the gene expression profiles of six common oral bacteria, including two Gram-positive bacteria (Actinomyces viscosus, Streptococcus mutans) and four Gram-negative bacteria (Porphyromonas gingivalis, Tannerella forsythia, Fusobacterium nucleatum, and Prevotella pallens), were analyzed. The bacteria were exposed to nine common ingredients in toothpaste and mouthwash at different concentrations (stannous fluoride, stannous chloride, arginine bicarbonate, cetylpyridinium chloride, sodium monofluorophosphate, sodium fluoride, potassium nitrate, zinc phosphate, and hydrogen peroxide). Across 78 ingredient–microorganism pairs with 360 treatment–control combinations, significant and reproducible ingredient-based transcriptional response profiles were observed, providing valuable insights into the effects of these ingredients on the oral microbiome at the molecular level. This research shows that oral care product ingredients applied at biologically relevant concentrations manifest differential effects on the transcriptomics of bacterial genes in a variety of oral periodontal pathogenic bacteria. Stannous fluoride, stannous chloride, and cetylpyridinium chloride showed the most robust efficacy in inhibiting the growth or gene expression of various bacteria and pathogenic pathways. Combining multiple ingredients targeting different mechanisms might be more efficient than single ingredients in complex oral microbiomes.

Objective: To characterize the scalp microbial composition, function, and connection to dandruff severity using a metagenomics approach and to understand the impact of a Piroctone Olamine containing anti‐dandruff shampoo on the scalp microbiome.Methods: Shotgun metagenomics was used to characterize the composition of the scalp microbiomes from 94 subjects with and without clinically defined dandruff. Furthermore, the microbiome of the scalps of 100 dandruff sufferers before and after 3 weeks of treatment with either control or anti‐dandruff shampoo containing 0.5% Piroctone Olamine (PO) was characterized and compared to identify microorganisms associated with the dandruff condition and the associated pathways and processes that may contribute to PO's effect on scalp microbiome.Results: A higher relative abundance of Malassezia restricta and Staphylococcus capitis and a lower abundance of Cutibacterium acnes were associated with the dandruff scalps relative to the no‐dandruff scalps. A 3‐week PO shampoo treatment reduced the relative abundance of Malassezia species and Staphylococcus capitis and increased the relative abundance of Cutibacterium acnes. This change to the scalp microbiome composition is consistent with a return to a healthy no‐dandruff microbiome and improved clinical signs and symptoms as measured by adherent scalp flaking score (ASFS) compared with the control shampoo. Functional genomics analysis showed that the PO shampoo treatment reduced oxidative stress‐associated genes and decreased the abundance of protease, urease, and lipase genes. These changes correlated positively to improvements in dandruff severity. PO treatment favourably shifted scalp microbiomes in dandruff subjects toward the no‐dandruff state.Conclusion: Our results suggest that part of the aetiology of dandruff can be attributed to dysbiosis of the scalp microbiome. PO treatment can restore a healthier microbiome, reducing oxidative stress and promoting better scalp health.

The heightened cardiovascular disease (CVD) risk observed among omnivores is thought to be linked, in part, to gut microbiota-dependent generation of trimethylamine-N-oxide (TMAO) from l-carnitine, a nutrient abundant in red meat. Gut microbial transformation of l-carnitine into trimethylamine (TMA), the precursor of TMAO, occurs via the intermediate γ-butyrobetaine (γBB). However, the interrelationship of γBB, red meat ingestion and CVD risks, as well as the gut microbial genes responsible for the transformation of γBB to TMA, are unclear. In the present study, we show that plasma γBB levels in individuals from a clinical cohort (n = 2,918) are strongly associated with incident CVD event risks. Culture of human faecal samples and microbial transplantation studies in gnotobiotic mice with defined synthetic communities showed that the introduction of Emergencia timonensis, a human gut microbe that can metabolize γBB into TMA, is sufficient to complete the carnitine → γBB → TMA transformation, elevate TMAO levels and enhance thrombosis potential in recipients after arterial injury. RNA-sequencing analyses of E. timonensis identified a six-gene cluster, herein named the γBB utilization (gbu) gene cluster, which is upregulated in response to γBB. Combinatorial cloning and functional studies identified four genes (gbuA, gbuB, gbuC and gbuE) that are necessary and sufficient to recapitulate the conversion of γBB to TMA when coexpressed in Escherichia coli. Finally, reanalysis of samples (n = 113) from a clinical, randomized diet, intervention study showed that the abundance of faecal gbuA correlates with plasma TMAO and a red meat-rich diet. Our findings reveal a microbial gene cluster that is critical to dietary carnitine → γBB → TMA → TMAO transformation in hosts and contributes to CVD risk.

At birth, human infants are poised to survive in harsh, hostile conditions. An understanding of the state of newborn skin development and maturation is key to the maintenance of health, optimum response to injury, healing and disease. The observational study collected full-thickness newborn skin samples from 27 infants at surgery and compared them to skin samples from 43 adult sites protected from ultraviolet radiation exposure, as the standard for stable, mature skin. Transcriptomics profiling and gene set enrichment analysis were performed. Statistical analysis established over 25,000 differentially regulated probe sets, representing 10,647 distinct genes, in infant skin compared to adult skin. Gene set enrichment analysis showed a significant increase in 143 biological processes (adjusted p < 0.01) in infant skin, versus adult skin samples, including extracellular matrix (ECM) organization, cell adhesion, collagen fibril organization and fatty acid metabolic process. ECM organization and ECM structure organization were the biological processes in infant skin with the lowest adjusted P-value. Genes involving epidermal development, immune function, cell differentiation, and hair cycle were overexpressed in adults, representing 101 significantly enriched biological processes (adjusted p < 0.01). The processes with the highest significant difference were skin and epidermal development, e.g., keratinocyte differentiation, keratinization and cornification intermediate filament cytoskeleton organization and hair cycle. Enriched Gene Ontology (GO) biological processes also involved immune function, including antigen processing and presentation. When compared to ultraviolet radiation-protected adult skin, our results provide essential insight into infant skin and its ability to support the newborn’s preparedness to survive and flourish, despite the infant’s new environment laden with microbes, high oxygen tension and potential irritants. This fundamental knowledge is expected to guide strategies to protect and preserve the features of unperturbed, young skin.

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