The skin microbiome

The Neovaginal Microbiota, Symptoms, and Local Immune Correlates in Transfeminine Individuals with Penile Inversion Vaginoplasty

Transfeminine people (assigned male at birth) often undergo penile inversion vaginoplasty to create vulva, a clitoris and a vaginal canal (referred to as a neovagina). After vaginoplasty, transfeminine people frequently experience gynecological concerns but their etiology is unknown due to a lack of knowledge of the neovaginal microenvironment. We characterized neovaginal microbiota and cytokines in 47 transfeminine participants. Participants self-reported sexual behaviors and symptoms, enabling correlation with bacterial (16S rRNA) and immune profiles. Four distinct clusters of co-occurring bacteria with unique immune profiles were identified. One cluster, which included Fastidiosipila , Ezakiella , and Murdochiella , was abundant, stable, and correlated with lower cytokines. Conversely, another cluster containing Howardella , Parvimonas , Fusobacterium , and Lawsonella was linked to higher cytokines. Although Lactobacillus was detected, Lactobacillus -dominance was rare. These findings underscore the need for evidence-based clinical guidelines tailored to transfeminine gynecologic care, emphasizing the vital role of the neovaginal microbiome in symptom management and sexual health.

Mushrooms in modern cosmetics: unlocking anti-aging, antioxidant, and therapeutic potential

Mushrooms have gained significant attention in the cosmetics industry due to their rich bioactive compounds with numerous skin benefits. This review explores the potential of various mushroom species as ingredients in cosmeceuticals, focusing on their anti-aging, anti-wrinkle, skin whitening, moisturizing, antioxidant, anti-inflammatory, and antimicrobial properties. Mushrooms such as Ganoderma lucidum, Lentinula edodes, Pleurotus ostreatus, and Agaricus bisporus have demonstrated the ability to inhibit key enzymes like elastase, tyrosinase, hyaluronidase, and collagenase, which play vital roles in skin aging and pigmentation. These bioactive compounds, including polysaccharides, phenolic acids, vitamins, and carotenoids, contribute to reduce wrinkles, improving skin hydration, enhancing elasticity, and providing protection from oxidative stress and UV damage. Furthermore, mushrooms have shown antimicrobial activities, making them effective against skin infections and inflammation. Mushrooms have become a popular ingredient in hair care products for their nourishing benefits, helping to promote healthy hair growth and protect against damage. As demand for natural, sustainable, and effective skincare alternatives rises, the incorporation of mushrooms into cosmetic formulations offers a promising solution. This review highlights the growing application of mushrooms in the development of innovative cosmeceuticals and emphasizes the need for further research to explore their full potential. Advancements in extraction techniques and the identification of new bioactive compounds are expected to enhance the efficacy of mushroom-based skincare products, making them an integral part of the global cosmetics market in the future.

Analysis of the Culturable Skin Microbiome of Horses from Southern Germany

Horses have close interactions with humans and are important as working animals and livestock. In contrast to smaller companion animals like cats and dogs, there is only little information available about their skin microbiome. The objective of this study was to identify and characterize the culturable cutaneous microbiome of healthy horses. Samples were taken from 14 horses from Southern Germany which were randomly enrolled in this study. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a method to detect the culturable microorganisms of horse skin. The most abundant culturable species of horse skin identified in this study include Bacillus cereus, Bacillus pumilus, Carnobacterium inhibens, Exiguobacterium sibiricum, Macrococcus carouselicus, Macrococcus goetzii and Staphylococcus equorum. Analyses of the bacteria across different body regions indicated the specific preferences of species for certain skin areas. In addition, our data hinted to an influence of the age of the horses tested and an influence between the four stables studied.

Absolute quantification of the living skin microbiome overcomes relic-DNA bias and reveals specific patterns across volunteers

BACKGROUND

As the first line of defense against external pathogens, the skin and its resident microbiota are responsible for protection and eubiosis. Innovations in DNA sequencing have significantly increased our knowledge of the skin microbiome. However, current characterizations do not discriminate between DNA from live cells and remnant DNA from dead organisms (relic DNA), resulting in a combined readout of all microorganisms that were and are currently present on the skin rather than the actual living population of the microbiome. Additionally, most methods lack the capability for absolute quantification of the microbial load on the skin, complicating the extrapolation of clinically relevant information.

RESULTS

Here, we integrated relic-DNA depletion with shotgun metagenomics and bacterial load determination to quantify live bacterial cell abundances across different skin sites. Though we discovered up to 90% of microbial DNA from the skin to be relic DNA, we saw no significant effect of this on the relative abundances of taxa determined by shotgun sequencing. Relic-DNA depletion prior to sequencing strengthened underlying patterns between microbiomes across volunteers and reduced intraindividual similarity. We determined the absolute abundance and the fraction of population alive for several common skin taxa across body sites and found taxa-specific differential abundance of live bacteria across regions to be different from estimates generated by total DNA (live + dead) sequencing.

CONCLUSIONS

Our results reveal the significant bias relic DNA has on the quantification of low biomass samples like the skin. The reduced intraindividual similarity across samples following relic-DNA depletion highlights the bias introduced by traditional (total DNA) sequencing in diversity comparisons across samples. The divergent levels of cell viability measured across different skin sites, along with the inconsistencies in taxa differential abundance determined by total vs live cell DNA sequencing, suggest an important hypothesis for certain sites being susceptible to pathogen infection. Overall, our study demonstrates a characterization of the skin microbiome that overcomes relic-DNA bias to provide a baseline for live microbiota that will further improve mechanistic studies of infection, disease progression, and the design of therapies for the skin. Video Abstract.

Prostate Biopsy: The Transperineal Approach Is Better!

Transperineal prostate biopsy offers advantages over transrectal biopsy in terms of cancer detection in specific prostate areas, potential use of larger-gauge needles for tissue sampling, a lower risk of severe infectious complications such as sepsis, and lower use of antibiotic prophylaxis, aligning with antibiotic stewardship policies and reducing the risk of antimicrobial resistance and gut microbiome changes.

Analysis of global trends and hotspots of skin microbiome in acne: a bibliometric perspective

BACKGROUND

Acne is a chronic inflammatory condition affecting the hair follicles and sebaceous glands. Recent research has revealed significant advances in the study of the acne skin microbiome. Systematic analysis of research trends and hotspots in the acne skin microbiome is lacking. This study utilized bibliometric methods to conduct in-depth research on the recognition structure of the acne skin microbiome, identifying hot trends and emerging topics.

METHODS

We performed a topic search to retrieve articles about skin microbiome in acne from the Web of Science Core Collection. Bibliometric research was conducted using CiteSpace, VOSviewer, and R language.

RESULTS

This study analyzed 757 articles from 1362 institutions in 68 countries, the United States leading the research efforts. Notably, Brigitte Dréno from the University of Nantes emerged as the most prolific author in this field, with 19 papers and 334 co-citations. The research output on the skin microbiome of acne continues to increase, with Experimental Dermatology being the journal with the highest number of published articles. The primary focus is investigating the skin microbiome's mechanisms in acne development and exploring treatment strategies. These findings have important implications for developing microbiome-targeted therapies, which could provide new, personalized treatment options for patients with acne. Emerging research hotspots include skincare, gut microbiome, and treatment.

CONCLUSION

The study's findings indicate a thriving research interest in the skin microbiome and its relationship to acne, focusing on acne treatment through the regulation of the skin microbiome balance. Currently, the development of skincare products targeting the regulation of the skin microbiome represents a research hotspot, reflecting the transition from basic scientific research to clinical practice.

Prostate Biopsy: The Transperineal Approach is Better!

Transperineal prostate biopsy offers advantages over transrectal biopsy in terms of cancer detection in specific prostate areas, potential use of larger-gauge needles for tissue sampling, a lower risk of severe infectious complications such as sepsis, and lower use of antibiotic prophylaxis, aligning with antibiotic stewardship policies and reducing the risk of antimicrobial resistance and gut microbiome changes.

Unjustified use of amber necklaces for teething symptoms alleviation: Succinic acid release underperforms compared with natural skin bacteria production

BACKGROUND

There is limited evidence of succinic acid release from amber necklace that justifies its biological plausibility.

AIM

This study aimed to evaluate the release of succinic acid from Baltic amber beads in the presence of Staphylococcus epidermidis.

DESIGN

The Baltic amber beads from the necklace were stratified according to their weight (average 0.05 g ± 0.067). Subsequently, the beads (n = 8) were submerged in 0.9% buffered saline (Control) or brain-heart infusion culture medium in the presence of a commercial strain of S. epidermidis, a resident skin bacterium incubated at 37°C for 24 h or 7 days. The samples were centrifuged, and the supernatants were analyzed by 1H Nuclear Magnetic Resonance. Multivariate analyses were adopted using the sparse partial least squares discriminant analysis method (p < .05).

RESULTS

The group incubated with saline solution showed small release of succinic acid only after 7 days. In the groups with S. epidermidis, the release of succinic acid was observed in the both presence and absence of amber beads, indicating that succinic acid is a product released by bacteria.

CONCLUSIONS

It was found that amber beads do not exhibit the ability to release expressive succinic acid, especially in a short period of time, which does not justify their use in infants. The most production of succinic acid is tributed to S. epidermidis.

Skin Microbiome Dynamics in Atopic Dermatitis: Understanding Host-Microbiome Interactions

Atopic dermatitis (AD) is a chronic inflammatory skin disorder affecting both children and adults, characterized by pruritus, eczematous lesions, and compromised skin barrier function. A key feature of AD is dysbiosis of the skin microbiome, marked by reduced microbial diversity and the overgrowth of Staphylococcus aureus in lesional skin. S. aureus exacerbates skin barrier dysfunction and immune dysregulation, leading to recurrent infections and disease flares. In contrast, commensal bacteria such as Staphylococcus epidermidis and Roseomonas mucosa may exert protective effects by inhibiting S. aureus colonization and modulating immune responses. Beyond microbial composition, microbial metabolites play a crucial role in AD pathophysiology. Short-chain fatty acids, indole derivatives, and other bacterial metabolites influence cutaneous immune responses, lipid metabolism, and skin barrier integrity. Altered metabolite profiles, including reduced levels of beneficial microbial metabolites, are associated with AD severity and disease progression. Notably, S. aureus overabundance correlates with disruption in lipid metabolism, further compromising the skin barrier. This review explores recent advances in understanding the relationship between microbial metabolites and AD pathogenesis and examines the therapeutic potential of microbiome-targeted interventions. Strategies such as probiotics, prebiotics, and topical microbiome transplantation aim to restore microbial diversity and rebalance metabolite production, ultimately improving clinical outcomes in AD patients. Future therapeutic approaches focusing on commensal-derived metabolites offer promising avenues for alleviating symptoms and modulating disease severity in AD.

Comparative Whole Metagenome Analysis in Lesional and Nonlesional Scalp Areas of Patients with Psoriasis Capitis and Healthy Individuals

Psoriasis is an immune-mediated inflammatory disorder, where the majority of the patients suffer from psoriasis capitis or scalp psoriasis. Current therapeutics remain ineffective to treat scalp lesions. In this study, we present a whole-metagenome characterization of the scalp microbiome in psoriasis capitis. We investigated how changes in the homeostatic cutaneous microbiome correlate with the condition and identified metagenomic biomarkers (taxonomic, functional, virulence factors, antimicrobial resistance genes) that could partly explain its emergence. Within this study, 83 top and back scalp samples from healthy individuals and 64 lesional and nonlesional scalp samples from subjects with untreated psoriasis capitis were analyzed. Using qPCR targeting the 16S and 18S ribosomal RNA genes, we found a significant decrease in microbial load within scalp regions affected by psoriasis compared with that in their nonlesional counterparts. Metagenomic analysis revealed that psoriatic lesions displayed significant lower Cutibacterium species (including C. modestum, C. namnetense, C. granulosum, C. porci), along with an elevation in Staphylococcus aureus. A heightened relative presence of efflux pump protein-encoding genes was detected, suggesting potential antimicrobial resistance mechanisms. These mechanisms are known to specifically target human antimicrobial peptides (including cathelicidin LL-37), which are frequently encountered within psoriasis lesions. These shifts in microbial community dynamics may contribute to psoriasis disease pathogenesis.

Environmental factors and host sex influence the skin microbiota structure of Hong Kong newt (Paramesotriton hongkongensis) in a coldspot of chytridiomycosis in subtropical East Asia

Chytridiomycosis, an infectious skin disease caused by the chytrid fungi, Batrachochytrium dendrobatidis and B. salamandrivorans, poses a significant threat to amphibian biodiversity worldwide. Antifungal bacteria found on the skin of chytrid-resistant amphibians could potentially provide defense against chytridiomycosis and lower mortality rates among resistant individuals. The Hong Kong newt (Paramesotriton hongkongensis) is native to East Asia, a region suspected to be the origin of chytrids, and has exhibited asymptomatic infection, suggesting a long-term coexistence with the chytrids. Therefore, the skin microbiota of this resistant species warrant investigation, along with other factors that can affect the microbiota. Among the 149 newts sampled in their natural habitats in Hong Kong, China, putative antifungal bacteria were found in all individuals. There were 314 amplicon sequence variants distributed over 25 genera of putative antifungal bacteria; abundant ones included Acinetobacter, Flavobacterium, and Novosphingobium spp. The skin microbiota compositions were strongly influenced by the inter-site geographical distances. Despite inter-site differences, we identified some core skin microbes across sites that could be vital to P. hongkongensis. The dominant cores included the family Comamonadaceae, family Chitinophagaceae, and class Betaproteobacteria. Moreover, habitat elevation and host sex also exhibited significant effects on skin microbiota compositions. The antifungal bacteria found on these newts offer an important resource for conservation against chytridiomycosis, such as developing probiotic treatments for susceptible species.

Do Melanocytes Have a Role in Controlling Epidermal Bacterial Colonisation and the Skin Microbiome?

In addition to producing melanin to protect epidermal keratinocytes against DNA damage, melanocytes may have important roles in strengthening innate immunity against pathogens. We have developed a functional, pigmented, human full-thickness 3D skin equivalent to determine whether the presence of melanocytes impacts epidermal bacterial growth and regulates the expression of genes involved in the immune response. We introduced primary epidermal melanocytes to construct a 3-cell full-thickness skin equivalent with primary dermal fibroblasts and epidermal keratinocytes. Immunohistochemistry verified the appropriate ratio and spatial organisation of melanocytes. Alpha-MSH induced melanogenesis, confirming an appropriate physiological response. We compared this 3-cell skin equivalent with the 2-cell version without melanocytes in response to inoculation with 3 species of bacteria: Staphylococcus epidermidis, Corynebacterium striatum, and Cutibacterium acnes. There was a significant decrease in the colonisation of bacteria in the skin equivalents containing functional melanocytes. There was increased expression of immune-response genes (S100A9, DEFB4A, IL-4R) following microorganism exposure; however, there were marked differences between the unpigmented and pigmented skin equivalents. This physiologically relevant human 3D-skin equivalent opens up new avenues for studying complex skin pigmentation disorders, melanoma, and UV damage, as well as the rapidly evolving field of the skin microbiome and the balance between commensal and pathogenic species.

Mapping the microbial landscape and variations based on biological sex, age, and biopsy location in the shoulder skin microbiome

BACKGROUND

The organisms responsible for periprosthetic joint infections (PJIs) of the shoulder are often skin pathogens originating from the patient's own skin flora at the time of surgery. Understanding the normal skin flora around the shoulder is an important step to identify the range of organisms that could be responsible for PJI and to ensure optimization of culture mediums to identify them. This study aimed to provide the first description of the shoulder skin microbiome using high-throughput next-generation sequencing methodology and explore variations by age, biological sex, and biopsy location.

METHODS

Patients undergoing arthroscopic surgery were approached for informed consent to have punch biopsies taken from anterior, lateral, and posterior arthroscopy portal sites. DNA extraction was undertaken followed by illumina sequencing, focusing on the V3-V4 regions of the 16S rRNA gene. Amplicon sequence variants (ASVs) were generated using Deblur workflow and used for taxonomic assignment. Variation in the microbiota community based on age, biological sex, and biopsy location was assessed through alpha and beta diversity metric calculations using phyloseq R package.

RESULTS

Sixty-two patients (24 female, 38 male) aged 18-80 years were recruited, resulting in 186 punch biopsy samples for analysis. Following removal of low-prevalence taxa, 606 ASVs were aggregated at the genus level, resulting in 214 genera across 13 phyla. The top 20 most abundant genera accounted for 73.5% of the overall sequence count. Cutibacterium was the most abundant genus within the study population, followed by Ralstonia, Staphylococcus, Bacteroides, and Streptococcus. Significant differences were observed in beta diversity metrics when comparing by biological sex, which accounted for 3.9%-5.3% of the variation in the microbial community, but not age or biopsy location. Males displayed a greater proportion of gram-positive and aerobic bacteria, whereas females exhibited a greater proportion of gram-negative and stress-tolerant bacteria.

CONCLUSION

This is the first study to look specifically at the microbiome of the cutaneous shoulder and describe the most abundant genera and compositional differences based on age, biological sex, and biopsy location. Biological sex was the only host covariant studied that reached significance in explaining microbiota variation. The top 20 most abundant genera, accounting for 74% of the overall sequence count, would be isolated with standard microbiological culture. As such, this study does not highlight a need to change current culture investigation practice for shoulder PJI, but it serves as an important catalog of skin commensals around the operative site in shoulder surgery.

Are high cutibacterium bacterial loads at the time of revision shoulder arthroplasty associated with more severe clinical signs or symptoms or increased risk of recurrent periprosthetic joint infection?

PURPOSE

Cutibacterium is commonly isolated from deep tissue samples taken at the time of revision shoulder arthroplasty, but the significance of these positive cultures is debated, and the impact of increasing bacterial loads on clinical outcomes is unclear. The objectives of this study were to (1) identify factors independently associated with high bacterial loads, and (2) compare patient-reported outcomes (PROs) and revision rates in patients found to have high Cutibacterium loads.

MATERIALS AND METHODS

Male patients undergoing single stage exchange with a minimum 2-year follow-up were included. Culture data were semi-quantitatively scored with the total Cutibacterium score (TShCuS). Two groups were compared: patients with a High Cutibacterium Load (HCL) group and those with Low Cutibacterium Load (LCL) group. PROs and revision rates were compared, and a multivariable analysis was conducted.

RESULTS

Of 68 male patients that underwent revision shoulder arthroplasty, 29 (42.6%) met the inclusion criteria for the HCL group, while 27 patients (39.7%) were in the LCL group. Mean follow-up was 4.7 ± 3 years. Patients with intraoperative humeral loosening had an 18.4 times increased risk of having high Cutibacterium loads (95% CI 2.1-154.4, p < 0.001). There were no significant differences in PROs or re-revision rates between the HCL and LCL groups.

CONCLUSIONS

Intraoperative humeral loosening was independently associated with high Cutibacterium loads found at the time of revision shoulder arthroplasty. Male patients with high bacterial loads treated with complete single stage exchange and antibiotics had patient-reported outcomes similar to those of patients with minimal to no load.

LEVEL OF EVIDENCE

III.

Pumping the Breaks on Acantholytic Skin Disorders: Targeting Calcium Pumps, Desmosomes, and Downstream Signaling in Darier, Hailey-Hailey, and Grover Disease

Acantholytic skin disorders, by definition, compromise intercellular adhesion between epidermal keratinocytes. The root cause of blistering in these diseases traces back to direct disruption of adhesive cell-cell junctions, exemplified by autoantibody-mediated attack on desmosomes in pemphigus. However, genetic acantholytic disorders originate from more indirect mechanisms. Darier disease and Hailey-Hailey disease arise from mutations in the endoplasmic reticulum calcium pump, SERCA2, and the Golgi calcium/manganese pump, SPCA1, respectively. Though the disease-causing mutations have been known for nearly 25 years, the mechanistic linkage between dysregulation of intracellular ion stores and weakening of cell-cell junctions at the plasma membrane remains puzzling. The molecular underpinnings of a related idiopathic disorder, Grover disease, are even less understood. Due to an incomplete understanding of acantholytic pathology at the molecular level, these disorders lack proven, targeted treatment options, leaving patients with the significant physical and psychological burdens of chronic skin blistering, infections, and pain. This article aims to review what is known at the molecular, cellular, and clinical levels regarding these under-studied disorders and to highlight knowledge gaps and promising ongoing research. Armed with this knowledge, our goal is to aid investigators in defining essential questions about disease pathogenesis and to accelerate progress toward novel therapeutic strategies.

Unilateral Papulopustular Dermatosis: Demodex Mites Bridging Rosacea and Demodicosis

Papulopustular rosacea (PPR) is a common inflammatory dermatosis often associated with Demodex mite proliferation, though its pathogenesis remains incompletely understood. While bilateral presentations predominate, unilateral cases are rare and may offer unique insights into disease mechanisms. We report a case of a 68-year-old female with a chronic erythematous and scaly rash confined to the right malar region. Standardized skin surface biopsy revealed a high Demodex density (>5 mites/cm²), confirming demodicosis. Treatment with topical ivermectin cream resulted in significant improvement within four weeks. This case underscores the importance of considering demodicosis in the differential diagnosis of atypical facial dermatoses and revisits the classification, pathogenesis, diagnostic algorithm, and treatment strategies for inflammatory facial conditions. The findings support the inclusion of Demodex proliferation in disease frameworks and its potential impact on tailored therapeutic approaches.

The Skin Microbiome: A New Key Player in Melanoma, From Onset to Metastatic Stage

The skin microbiome plays a crucial role in maintaining skin health, defending the body against harmful pathogens, and interacting with melanoma. The composition of the skin microbiome can be affected by factors like age, gender, ethnicity, lifestyle, diet, and UV exposure. Certain bacteria like Staphylococcus and Veillonella are important for wound healing, while Cutibacterium acnes can play a role in dermatoses. UV radiation alters the skin microbiome, originates a "UV-resistome" and can lead to skin cancer initiation. Specifically, Staphylococcus epidermidis has shown protective effects against skin cancer, whereas Cutibacterium acnes can induce apoptosis in melanocytes postirradiation. The microbiome also interacts with melanoma treatment, affecting responses to immune checkpoint inhibitors. Strategies like bacteriotherapy, involving the manipulation of the gut microbiome but also the skin microbiome (with the gut-skin axis or through topical treatment) could improve treatment outcomes and show promise in melanoma therapy. Understanding the complex interplay between the skin microbiome, UV exposure, and melanoma development is crucial for developing personalized therapeutic approaches. Investigation into the skin microbiome and its potential role in melanoma progression continues to be an exciting area of research with implications for future therapeutic interventions.

Skin microbiota variation in Indian families

Background

In India, joint families often encompass members spanning multiple generations cohabiting in the same household, thereby sharing the same ethnicity, genetics, dietary habits, lifestyles, and other living conditions. Such an extended family provides a unique opportunity to evaluate the effect of genetics and other confounding factors like geographical location, diet and age on the skin microbiota within and between families across three generations.

Methods

The present study involved seventy-two individuals from fifteen families from two geographical regions of Maharashtra, India. The 16S rRNA sequencing of V3-V4 regions was performed and the generated taxonomic profiles were used for downstream analysis.

Results

Our study highlights a significant difference in community composition (beta diversity) between families (PERMANOVA; p = 0.001) and geographical locations (p = 0.001). We observed geographical location-wise differences in the relative abundances Staphylococcus in the families from Pune (Wilcoxon test, p = 0.007), and Bacillus in the Ahmednagar families (Wilcoxon test, p = 0.004). When within and between-family comparisons of skin microbiota composition were carried out between different generations (G1-G2, G2-G3, and G1-G3); we observed skin microbiota tended to be more similar within than between families but this difference was not significant.

Conclusion

This study underscores the diversity and commonalities in skin microbiota composition within and between families. Our result suggests that geographical location is significantly associated with the genus composition of skin microbiota, which is quantitatively unique for a family and likely explained by co-habitation.

Gut phages and their interactions with bacterial and mammalian hosts

The mammalian gut microbiome is a dense and diverse community of microorganisms that reside in the distal gastrointestinal tract. In recent decades, the bacterial members of the gut microbiome have been the subject of intense research. Less well studied is the large community of bacteriophages that reside in the gut, which number in the billions of viral particles per gram of feces, and consist of considerable unknown viral "dark matter." This community of gut-residing bacteriophages, called the gut "phageome," plays a central role in the gut microbiome through predation and transformation of native gut bacteria, and through interactions with their mammalian hosts. In this review, we will summarize what is known about the composition and origins of the gut phageome, as well as its role in microbiome homeostasis and host health. Furthermore, we will outline the interactions of gut phages with their bacterial and mammalian hosts, and plot a course for the mechanistic study of these systems.

Crosstalk Between the Skin Environment and Microbial Community in Immune-Related Skin Diseases

The skin surface hosts diverse skin microbiota, including bacteria, fungi, and viruses. Intricate interactions between the skin microenvironment and microbial community are crucial for maintaining cutaneous homeostasis. This review explores the bidirectional relationship between the skin ecosystem and its microbiota. The skin microenvironment is shaped by a combination of intrinsic factors, dominated by sweat glands and pilosebaceous units, and external factors, such as UV radiation and personal care products, which create distinct niches that influence microbial colonization patterns across different skin regions. The skin microbiome, in turn, modulates the physical, chemical, immunological, and microbial barriers of the skin. We also discuss the alterations in this crosstalk in various immune-related skin conditions such as atopic dermatitis, psoriasis, rosacea, hidradenitis suppurativa, skin cancer, and aging. Understanding these interactions is vital for developing targeted microbiome-based therapies for various skin disorders. Further researches are needed to deepen insights into the microbial roles and their therapeutic potentials in skin health and disease.

Skin microbiome differences in pancreatic adenocarcinoma, other cancers, and healthy controls: a pilot study

Introduction

Many studies have reported the importance of the human microbiome in relationship to the overall health of its host. While recent studies have explored the microbiome's role in various types of cancer compared to healthy patients, this pilot study is the first to investigate differences in the skin microbiome composition among pancreatic adenocarcinoma patients, individuals with other cancers, and cancer-free controls.

Methods

The study characterizes the skin microbiome's potential associations with cancer status by analyzing skin swabs from the forehead and cheek of 58 participants using Next Generation Sequencing (NGS), differential abundance analysis, and machine learning techniques.

Results

The study results indicated that the cancer group displayed a significantly higher mean alpha diversity compared to the control group. Additionally, a machine learning classification model achieved a mean F1 Score of 0.943 in predicting cancer status, indicating measurable differentiation in the skin microbiome between the study groups. This differentiation is supported by differential abundance methods, including ANCOM-BC and MaAsLin2.

Discussion

This pilot study suggests that skin microbiome profiling could serve as a non-invasive biomarker for cancer detection and monitoring, which warrants a larger, longitudinal study to validate these results.

Chlorhexidine vs Routine Foot Washing to Prevent Diabetic Foot Ulcers: A Randomized Clinical Trial

Importance

Foot ulcers are a common and feared complication for people with diabetes because 20% of foot ulcers become infected and lead to a lower extremity amputation.

Objective

To evaluate the effect of daily foot care using chlorhexidine wipes vs soap-and-water wipes for 1 year on the risk of developing new foot complications in veterans with diabetes.

Design, Setting, and Participants

This double-blind, placebo-controlled, phase 2b randomized clinical trial was conducted at the Baltimore Veterans Affairs (VA) Medical Center between January 2019 to January 2023. Veterans were eligible if they had a diabetes diagnosis, were at high risk for diabetic foot complications, were ambulatory, had both feet, and did not have a current foot infection. Participants were randomly assigned 1:1 to receive either soap-and-water wipes (control group) or 2% chlorhexidine wipes (chlorhexidine group). Intention-to-treat data analysis was conducted from October 5, 2023, to April 24, 2024.

Intervention

Daily use of a 2% chlorhexidine wipe or a soap-and-water wipe on the feet for 1 year. Wipes were nearly identical in color, size, shape, thickness, feel, and scent. Both chlorhexidine and control groups received the same lotion for application on the feet after wipe use and education on foot self-care.

Main Outcomes and Measures

The primary outcome was time in days from randomization to new foot complication, including chronic foot ulcer, foot infection, or foot amputation.

Results

A total of 175 participants (170 males [97%]; mean [SD] age at enrollment, 68 [9] years; 1 Asian [1%], 117 Black or African American [67%], 53 White [30%] individuals) were randomly assigned to the chlorhexidine group (n = 88) or the control group (n = 87). Twelve participants (14%) in the chlorhexidine group and 14 participants (16%) in the control group developed a new foot complication within 1 year. Median (IQR) time from randomization to development of a new foot complication was 232 (115-315) days. The reduction in hazard of new foot complications in the chlorhexidine group compared with the control group was not significant (hazard ratio, 0.83; 95% CI, 0.39-1.80). The intervention was well tolerated, with 145 participants (83%) continuing it over the study period. Sixty adverse events occurred, but none was related to the study products or procedures.

Conclusions and Relevance

This randomized clinical trial found that daily use of chlorhexidine wipes for foot washing for 1 year did not lead to a significant reduction in the risk of new foot complications compared with daily use of soap-and-water wipes. The intervention was well tolerated, and the trial provides important lessons for future studies on diabetic foot ulcer prevention.

Trial Registration

ClinicalTrials.gov Identifier: NCT03503370.

Molecular Mechanisms and Therapeutic Implications of Long Non-coding RNAs in Cutaneous Biology and Disease

Human skin is the largest organ of the human body and accounts for approximately fifteen percent of the total bodyweight. Its main physiological role is to protect the body against a wide range of environmental factors including pathogens, ultraviolet light, and injury. Importantly, the skin can regenerate and heal upon injury in large part by the differentiation of keratinocytes. Not surprisingly, dysregulation of cutaneous differentiation and self-renewal can result in a variety of skin-related pathologies, including autoimmune disease and cancer. Increasing evidence supports the premise that long non-coding RNAs (lncRNAs) act as critical mediators of gene expression and regulate important biological processes within the skin. Notably, dysregulation of lncRNAs has been shown to influence diverse physiological and pathological consequences. More recently, numerous reports have revealed new mechanistic insight on the role that lncRNAs play in skin homeostasis as well as their contribution to the pathogenesis of skin-related disorders. Here, we review the biological functions of cutaneous lncRNAs and their impact on skin homeostasis. We also describe the fundamental roles of lncRNAs in the pathogenesis of skin-related disorders, including fibrotic, autoimmune, and malignant diseases. Lastly, we will highlight how a better understanding of lncRNAs at the molecular level may reveal novel therapeutic approaches for the improvement of cutaneous disorders.

The neonate respiratory microbiome

Over the past two decades, it has become clear that against earlier assumptions, the respiratory tract is regularly populated by a variety of microbiota even down to the lowest parts of the lungs. New methods and technologies revealed distinct microbiome compositions and developmental trajectories in the differing parts of the respiratory tract of neonates and infants. In this review, we describe the current understanding of respiratory microbiota development in human neonates and highlight multiple factors that have been identified to impact human respiratory microbiome development including gestational age, mode of delivery, diet, antibiotic treatment, and early infections. Moreover, we discuss to date revealed respiratory microbiome-disease associations in infants and children that may indicate a potentially imprinting cross talk between microbial communities and the host immune system in the respiratory tract. It becomes obvious how insufficient our knowledge still is regarding the exact mechanisms underlying such cross talk in humans. Lastly, we highlight strong findings that emphasize the important role of the gut-lung axis in educating and driving pulmonary immunity. Further research is needed to better understand the host - respiratory microbiome interaction in order to enable the translation into microbiome-based strategies to protect and improve human respiratory health from early childhood.

A review of artificial sebum formulations, their compositions, uses and physicochemical characteristics

Sebum is a complex mixture of skin lipids responsible for lubrication, moisture retention and skin protection from external factors such as bacteria and fungi. The physicochemical properties of natural sebum are not well understood and are not easily accessible. Artificial sebum is widely used for sebum-related research such as dermal bioaccessibility, fingerprint production, dermatology, removal and sebum studies. It was found that the composition of artificial sebum affects the bioaccessibility of metals and drugs as well as the growth of some strains of bacteria. Squalene present in sebum was also found to be responsible for creating yellow stains on fabrics, whereas an increased concentration of fatty acids and triglycerides can lead to higher malodour of fabrics. Moreover, sebum and artificial sebum are poorly characterized with only 20 of 81 formulations characterized by certain techniques such as differential scanning calorimetry, nuclear magnetic resonance and thin-layer chromatography. This article reviews the artificial sebum formulations reported in the open literature between 1965 and 2023. We have discussed the compositions, uses and characterization techniques of artificial sebum used in the previous work and compared their properties to those of human sebum. A total of 81 artificial sebum formulations were found across the literature with 17 new formulations identified. The artificial sebum composition varies greatly between publications and there is no consistent formulation. There is a wide range of chemicals that are used as the main components of artificial sebum. We have highlighted the effect of chemical composition and individual compounds on the overall properties of the artificial sebum reported, and recommend that there is a great potential for creating personalized cosmetics and home care products once the characteristics of sebum are better understood.

A Palearctic view of a bat fungal disease

The fungal infection causing white-nose disease in hibernating bats in North America has resulted in dramatic population declines of affected species, since the introduction of the causative agent Pseudogymnoascus destructans. The fungus is native to the Palearctic, where it also infects several bat species, yet rarely causes severe pathology or the death of the host. Pseudogymnoascus destructans infects bats during hibernation by invading and digesting the skin tissue, resulting in the disruption of torpor patterns and consequent emaciation. Relations among pathogen, host, and environment are complex, and individuals, populations, and species respond to the fungal pathogen in different ways. For example, the Nearctic Myotis lucifugus responds to infection by mounting a robust immune response, leading to immunopathology often contributing to mortality. In contrast, the Palearctic M. myotis shows no significant immunological response to infection. This lack of a strong response, resulting from the long coevolution between the hosts and the pathogen in the pathogen's native range, likely contributes to survival in tolerant species. After more than 15 years since the initial introduction of the fungus to North America, some of the affected populations are showing signs of recovery, suggesting that the fungus, hosts, or both are undergoing processes that may eventually lead to coexistence. The suggested or implemented management methods of the disease in North America have encompassed, for example, the use of probiotics and fungicides, vaccinations, and modifying the environmental conditions of the hibernation sites to limit the growth of the pathogen, intensity of infection, or the hosts' responses to it. Based on current knowledge from Eurasia, policy makers and conservation managers should refrain from disrupting the ongoing evolutionary processes and adopt a holistic approach to managing the epizootic.

A STRUCTURAL EQUATION MODEL PREDICTS CHRONIC WOUND HEALING TIME USING PATIENT CHARACTERISTICS AND WOUND MICROBIOME COMPOSITION

Wound etiology, host characteristics, and the wound microbiome contribute to chronic wound development. Yet, there is little accounting for the relative importance of these factors to predict wound healing. Here, a structural equation model was developed to provide such an explanatory and predictive framework. Chronic wounds from 565 patients treated at a clinic practicing biofilm-based wound care were included. Patient information included DNA sequencing-based wound microbiome clinical reports corresponding to initial clinical visit. Wound microbiome data was integrated into the SEM as a latent variable using a pre-modeling parcel optimization routine presented herein for the first time (available as R library parcelR). A microbiome latent construct associated with improved healing was validated, and the final SEM included this latent construct plus three species associated with diminished healing (Anaerococcus vaginalis, Finegoldia magna, Pseudomonas aeruginosa), as well as smoking, wound volume, slough, exudate, edema, percent granulation, and wound etiology This model explained 46% of variation in healing time with the microbiome contributing the largest proportion of variance explained. Model validity was confirmed with an independent cohort (n = 79) through which ~60% of variation in healing time was predicted. This model can serve as foundation for development of a predictive tool that may have clinical utility.

Single-cell sequencing of human Langerhans cells identifies altered gene expression profiles in patients with atopic dermatitis

Atopic dermatitis (AD) is characterized by dysregulated T cell immunity and skin microbiome dysbiosis with predominance of Staphylococcus aureus, which is associated with exacerbating AD skin inflammation. Specific glycosylation patterns of S. aureus cell wall structures amplify skin inflammation through interaction with Langerhans cells (LCs). Nevertheless, the role of LCs in AD remains poorly characterized. Here, we performed single cell RNA sequencing of primary epidermal LCs and dermal T cells, isolated from skin biopsies of AD patients and healthy control subjects, alongside specific glycoanalysis of S. aureus strains isolated from the AD lesions. Our findings revealed 4 LC subpopulations ie, 2 steady-state clusters [LC1 and LC1H] and 2 proinflammatory/matured subsets [LC2 and migratory LCs]. The latter 2 subsets were enriched in AD skin. AD LCs showed enhanced expression of C-type lectin receptors, the high-affinity IgE receptor, and activation of prostaglandin and leukotriene biosynthesis pathways, upregulated transcriptional signatures related to T cell activation pathways, and increased expression of CCL17 compared with healthy LCs. Correspondingly, T helper 2 and T regulatory cell populations were increased in AD lesions. Complementary, we performed bulk RNA sequencing of primary LCs stimulated with the S. aureus strains isolated from the AD lesions, which showed upregulation of T helper 2-related pathways. Our study provides proof-of-concept for a role of LCs in connecting the S. aureus-T cell axis in the AD inflammatory cycle.

Human microbiota peptides: important roles in human health

Covering: 1974 to 2024Human microbiota consist of a diverse array of microorganisms, such as bacteria, Eukarya, archaea, and viruses, which populate various parts of the human body and live in a cooperatively beneficial relationship with the host. They play a crucial role in supporting the functional balance of the microbiome. The coevolutionary progression has led to the development of specialized metabolites that have the potential to substitute traditional antibiotics in combating global health challenges. Although there has been a lot of research on the human microbiota, there is a considerable lack of understanding regarding the wide range of peptides that these microbial populations produce. Particularly noteworthy are the antibiotics that are uniquely produced by the human microbiome, especially by bacteria, to protect against invasive infections. This review seeks to fill this knowledge gap by providing a thorough understanding of various peptides, along with their in-depth biological importance in terms of human disorders. Advancements in genomics and the understanding of molecular mechanisms that control the interactions between microbiota and hosts have made it easier to find peptides that come from the human microbiome. We hope that this review will serve as a basis for developing new therapeutic approaches and personalized healthcare strategies. Additionally, it emphasizes the significance of these microbiota in the field of natural product discovery and development.

The role of multiomics in revealing the mechanism of skin repair and regeneration

Skin repair and regeneration are crucial processes in restoring the integrity of the skin after injury, with significant implications for medical treatments and plastic surgery. Multiomics, an integrated approach combining genomics, transcriptomics, proteomics, and metabolomics, offers unprecedented insights into the complex molecular and cellular mechanisms involved in skin healing. This review explores the transformative role of multiomics in elucidating the mechanisms of skin repair and regeneration. While genomic studies identify the genetic basis of wound healing, transcriptomics and proteomics uncover the dynamic changes in gene and protein expression, and metabolomics provides a snapshot of metabolic alterations associated with wound healing. Integrative multiomics studies can also identify novel biomarkers and therapeutic targets for skin regeneration. Despite the technical and biological challenges, the future of multiomics in skin research holds great promise for advancing personalized medicine and improving wound healing strategies. Through interdisciplinary collaboration, multiomics has the potential to revolutionize our understanding of skin repair, paving the way for innovative treatments in plastic surgery and beyond.

Population-specific differences in the human microbiome: Factors defining the diversity

Differences in microbial communities at different body habitats define the microbiome composition of the human body. The gut, oral, skin vaginal fluid and tissue microbiome, are pivotal for human development and immune response and cross talk between these microbiomes is evident. Population studies reveal that various factors, such as host genetics, diet, lifestyle, aging, and geographical location are strongly associated with population-specific microbiome differences. The present review discusses the factors that shape microbiome diversity in humans, and microbiome differences in African, Asian and Caucasian populations. Gut microbiome studies show that microbial species Bacteroides is commonly found in individuals living in Western countries (Caucasian populations), while Prevotella is prevalent in non-Western countries (African and Asian populations). This association is mainly due to the high carbohydrate, high fat diet in western countries in contrast to high fibre, low fat diets in African/ Asian regions. Majority of the microbiome studies focus on the bacteriome component; however, interesting findings reveal that increased bacteriophage richness, which makes up the virome component, correlates with decreased bacterial diversity, and causes microbiome dysbiosis. An increase of Caudovirales (bacteriophages) is associated with a decrease in enteric bacteria in inflammatory bowel diseases. Future microbiome studies should evaluate the interrelation between bacteriome and virome to fully understand their significance in the pathogenesis and progression of human diseases. With ethnic health disparities becoming increasingly apparent, studies need to emphasize on the association of population-specific microbiome differences and human diseases, to develop microbiome-based therapeutics. Additionally, targeted phage therapy is emerging as an attractive alternative to antibiotics for bacterial infections. With rapid rise in microbiome research, focus should be on standardizing protocols, advanced bioinformatics tools, and reducing sequencing platform related biases. Ultimately, integration of multi-omics data (genomics, transcriptomics, proteomics and metabolomics) will lead to precision models for personalized microbiome therapeutics advancement.

Biofilm Compositions and Bacterial Diversity on Kitchen Towels in Daily Use

Towels with complex woven structures are susceptible to biofilm formation during daily use. The composition of biofilms formed on towels used under real-life conditions has yet to be studied. Thus, we investigated the color changes, structural integrity, and biofilm development on towels used continuously for 10 weeks by 12 volunteers in specific kitchen environments. Apparent biofilms composed of bacteria and extracellular polymeric substances (EPSs) were found on all used towels. The bacteria concentrations ranged from 4 to 7 log CFU/g. Proteins were the most abundant EPS, followed by polysaccharides and eDNA. A high-throughput sequencing method was employed to investigate the bacterial diversity on the towels. The predominant bacterial genera differed from towel to towel. Kocuria, Rothia, Psychrobacter, Enhydrobacter, and Pseudomonas are genera of relatively high abundance that may originate from the human body and foods. In addition, correlations among environmental factors, major bacterial genera, physical properties, and biofilm formation of the towels were analyzed, which could provide a scientific reference for maintaining towel hygiene.

The association of dextran sodium sulfate to the bioactive agent I-modulia® attenuates Staphylococcus aureus virulence expression and δ-toxin production

As a part of the human skin commensal bacterial community, Staphylococcus aureus contributes to the host's immune system education. Nevertheless, it is also considered as an opportunistic pathogen involved in cutaneous infections or skin pathologies, in particular atopic dermatitis. To switch to a pathogenic behavior, S. aureus uses regulatory mechanisms to collectively produce virulence factors. Deprivation of these factors has emerged as a promising way to prevent or treat Staphylococcal diseases in facilitating the role of the immune system, while preserving the protective one of the commensal communities. This study focuses on the anti-virulent effect of dextran sodium sulfate (DSS) and I-modulia®, two natural products that have already proven their value in skincare. The anti-virulent capacity of DSS was first demonstrated by a dose-dependent inhibition of δ-toxin release, a virulence factor known to be a potent inducer of mast cell degranulation, on in vitro S. aureus cultures at high and low virulent states. A transcriptomic study was then implemented for a comprehensive overview of the anti-virulent impact. The results have shown the downregulation of many transcripts related to host immune evasion (scn, sbi), as well as exotoxins (α,γ-toxin) and adhesins production (map, emp), mostly under the control of SaeRS Two-Component System (TCS), one of the two major virulence regulators in S. aureus. Interestingly, genes related to secretion systems and the synthesis of exo-proteases were significantly downregulated when DSS was used in combination with I-modulia®. The repression of these genes was not previously observed and reflects a broader inhibitory action. We have also demonstrated that the inhibition of virulence factors didn't affect S. aureus viability. Our findings suggest that combining DSS and I-modulia® could be a promising therapeutic strategy to counteract microbial dysbiosis in the treatment of S. aureus skin pathologies in re-empowering the host's natural immune defenses.

The microbiome's influence on the neurobiology of opioid addiction and brain connectivity

BACKGROUND

Opioids are the most effective and potent analgesics available for acute pain management. With no viable alternative for treating chronic or post operative pain, it is not surprising that over 10 million people misuse opioids. This study explores the developmental influence of the microbiome on resistance to opioid addictive behavior and functional connectivity.

METHODS

Female germ free reared (GFR) mice were compared to wild-type (WT) mice, before and after conventionalization using conditioned place preference (CPP) with oxycodone (OXY) exposure. Functional connectivity data were collected providing site-specific analysis for over 140 different brain areas.

RESULTS

GFR mice showed significant reduction in CPP after OXY exposure. When GFR mice are conventionalized CPP reward behavior mirrors WT mice. Functional connectivity data shows significant differences across several brain regions e.g., thalamus, hippocampus, and sensory cortices between GFR and WT before and after conventionalization. Prior to conventionalization GFR mice showed hyperconnectivity that became less organized and more global after conventionalization. Sequencing of the fecal microbiome of the GFR mice before conventionalization showed an absence of normal murine gut microbiome members, but the presence of Corynebacterium, Staphylococcus, Paenibacillus, and Turicibacter.

CONCLUSION

The implications suggest the microbiome has a direct impact on the development of reward seeking behavior. With the widespread number of opioid receptors found in the gut, studying the interaction between the microbiota and substance use disorder may lead to a better understanding of the mechanisms that lead to the development of addiction as well as potential treatments.

Pressure injuries and biofilms: Microbiome, model systems and therapies

Chronic wounds have emerged as significant clinical problems owing to their increasing incidence and greater recognition of associated morbidity and socio-economic burden. They are defined as wounds that do not progress normally through the stages of healing in a timely and/or orderly manner. Pressure injuries, in particular, represent a serious problem for patients who are elderly or have limited mobility, such as wheelchair users or those who spend most of the day in bed. These injuries often result from prolonged pressure exerted on the skin over the bone. Treatment of pressure injuries is complex and costly. Emerging evidence suggests that the pressure injury microbiome plays a vital role in chronic wound formation and delaying wound healing. Additionally, antibiotics often fail due to the formation of resistant biofilms and the emergence of antimicrobial-resistant bacteria. In this review, we will summarise the current knowledge on: (a) biofilms and microbiomes in pressure injuries; (b) in vitro and in vivo model systems to study pressure injuries, and (c) current therapies and novel treatment approaches. Understanding the complex interactions between microbes and the host immune system in pressure injuries will provide valuable insights to improve patient outcomes.

Factors Associated With Increased Risk of Contamination in Bone Marrow Transplants

Hematopoietic cell transplantation (HCT) remains the definitive therapeutic modality for numerous malignant and non-malignant hematologic disorders. Conventional bone marrow remains a viable donor source for HCT. However, microbial contamination of bone marrow harvests may present a risk to immunocompromised recipients. This analysis sought to identify clinical factors associated with bone marrow contamination. We analyzed a single institution experience comprising 667 unique bone marrow harvests collected between 1999 and 2021. We trended the yearly microbial contamination rate over this time span. Harvest type (autologous versus allogenic), donor age, donor sex, physician experience, total nucleated cell (TNC) count, volume collected, and TNC concentration were included in a univariate (UV) and multivariate (MV) logistic model to assess which factors were associated with contamination. Males comprised 55.8% of the donor population and the median age of the cohort was 35 [IQR: 27 to 45]. There were 19 autologous, 151 related allogenic, and 497 unrelated allogenic transplants in this cohort. 87 of the 667 (13.0%) harvests were contaminated and essentially all contaminants were common skin flora. The yearly contamination rates displayed substantial variability, ranging from 0% to 42.9%, with no discernible trend. Harvest type did not exhibit a significant association with contamination risk. However, male donor sex was found to be significantly associated with a higher contamination rate (18%) compared to female sex (6.8%, P < .001). In both UV and MV logistic models, male sex emerged as the sole factor linked to contamination risk (OR: 2.90, 95% CI: 1.65 to 5.35). This analysis represents the largest single-center investigation of bone marrow harvest microbial contamination rates. Notably, it is the first to establish an association between contamination and male donor sex. We propose that this association may be attributed to differences in skin flora composition or innate immune function between sexes, general hygiene practices or possibly the result of the frequent clipping of body hair in males prior to the harvest procedure. Further research is warranted to explore the underlying mechanisms and clinical implications of this novel finding.

Influence of Cosmetic Skincare Products with pH < 5 on the Skin Microbiome: A Randomized Clinical Evaluation

INTRODUCTION

The human skin acts as a protective barrier against external pathogens and hosts a diverse microbiome consisting of bacteria, fungi, viruses, and archaea. Disruptions to the skin microbiome can impact immune function, leading to inflammatory and autoimmune conditions. The importance of pH for the microbiome is paramount. Cosmetic skincare products interact with the skin microbiome and skin pH, playing a key role in maintaining microbial balance. Research suggests that products with non-physiological pH levels may disrupt the skin microbiota. Our clinical study aimed to evaluate the effects of low-pH cosmetic products (pH < 5) on the skin microbiome, contributing to improved skin health.

METHODS

The clinical study focused on evaluating the skin microbiome diversity following the application for 28 days of four different low-pH cosmetic products (vitamin C, resveratrol, a collagen mask, and a native algae mask) on the forearms of post-menopausal women with skin pH > 5.5.

RESULTS

The diversity of the natural skin microbiome increased consistently throughout the study, evident in both the untreated area and after the application of the Vitamin C Concentrate, Resveratrol Concentrate, Collagen Mask, and Native Algae Mask, as indicated by Shannon's diversity index. The native algae mask notably reduced the Corynebacterium genus and significantly lowered the pH. The skin pH changes corresponded with microbiota stability.

CONCLUSIONS

In conclusion, enhanced diversity of the natural skin microbiome was observed over the study duration. None of the investigational products caused significant disruption to the skin microbiome diversity, as evidenced by the stable Shannon's diversity index and relative abundance of specific genera. Notably, the native algae mask significantly decreased the presence of the opportunistic pathogenic Corynebacterium genus, which is likely attributable to a minor reduction in skin pH following extended product use. The findings suggest that the use of low-pH skincare products, like the native algae mask, do not disrupt skin microbiome diversity and may have the potential to positively impact skin microbiome diversity and health by reducing certain pathogenic microbial populations.

Genetic Causal Association Between Skin Microbiota and Biological Aging: Evidence From a Mendelian Randomization Analysis

BACKGROUND

The skin microbiota, a complex community of microorganisms residing on the skin, plays a crucial role in maintaining skin health and overall homeostasis. Recent research has suggested that alterations in the composition and function of the skin microbiota may influence the aging process. However, the causal relationships between specific skin microbiota and biological aging remain unclear. Mendelian randomization (MR) analysis provides a powerful tool to explore these causal links by utilizing genetic variants as instrumental variables, thereby minimizing confounding factors and reverse causality that often complicate observational studies.

METHODS

We utilized a two-sample MR approach with population-based cross-sectional data from two German cohorts, KORA FF4 (n = 324) and PopGen (n = 273). In total, GWAS summary data from 1656 skin samples and datasets on accelerated biological age were analyzed to investigate the causal relationship between skin microbiota and accelerated biological aging. The primary analysis was performed using the inverse variance weighted (IVW) method with random effects and was further supported by MR-Egger regression, Cochran's Q test, and a range of sensitivity analyses.

RESULTS

The MR analysis revealed that for biological age acceleration (BioageAccel), the IVW analysis identified protective effects from certain skin microbiota, including Alphaproteobacteria_Dry (p = 0.046), Asv033_sebaceous (p = 0.043), Burkholderiales_Moist (p = 0.008), and Proteobacteria_Moist (p = 0.042). Similar protective effects were observed for Burkholderiales_Moist (p = 0.045) and Proteobacteria_Moist (p = 0.012) in the weighted median analysis. In contrast, Paracoccus_Moist (p = 0.013) and Proteobacteria_Sebaceous (p = 0.005) were associated with accelerated aging. When using PhenoAge acceleration as the outcome, the IVW analysis linked skin microbiota like Asv005_Dry (p = 0.026), ASV039_Dry (p = 0.003), Betaproteobacteria_Sebaceous (p = 0.038), and Chryseobacterium_Moist (p = 0.013) with accelerated aging. The weighted median analysis supported these findings and also identified protective effects from ASV011_Dry (p = 0.021), ASV023_Dry (p = 0.040), Bacteroidales_Dry (p = 0.022), Enhydrobacter_Moist (p = 0.038), Proteobacteria_Moist (p = 0.002), and Rothia_Moist (p = 0.038).

CONCLUSIONS

This two-sample MR study reveals potential causal relationships between skin microbiota and aging. However, to confirm these findings, further randomized controlled trials (RCTs) are necessary.

Exploring the impact of solar radiation on skin microbiome to develop improved photoprotection strategies

The skin microbiome undergoes constant exposure to solar radiation (SR), with its effects on health well-documented. However, understanding SR's influence on host-associated skin commensals remains nascent. This review surveys existing knowledge on SR's impact on the skin microbiome and proposes innovative sun protection methods that safeguard both skin integrity and microbiome balance. A team of skin photodamage specialists conducted a comprehensive review of 122 articles sourced from PubMed and Research Gateway. Key terms included skin microbiome, photoprotection, photodamage, skin cancer, ultraviolet radiation, solar radiation, skin commensals, skin protection, and pre/probiotics. Experts offered insights into novel sun protection products designed not only to shield the skin but also to mitigate SR's effects on the skin microbiome. Existing literature on SR's influence on the skin microbiome is limited. SR exposure can alter microbiome composition, potentially leading to dysbiosis, compromised skin barrier function, and immune system activation. Current sun protection methods generally overlook microbiome considerations. Tailored sun protection products that prioritize both skin and microbiome health may offer enhanced defense against SR-induced skin conditions. By safeguarding both skin and microbiota, these specialized products could mitigate dysbiosis risks associated with SR exposure, bolstering skin defense mechanisms and reducing the likelihood of SR-mediated skin issues.

Staphylococcus lugdunensis does not exert competitive exclusion on human corneocytes

Human skin is our primary physical barrier and largest immune organ, and it also hosts a protective microbiota. Staphylococci are prominent members of the skin microbiota, including the ubiquitous coagulase-negative staphylococci (CoNS). The coagulase-positive Staphylococcus aureus is found as part of the microbiota, but it poses clinical concern due to its potential pathogenicity and antibiotic resistance. Recently, a CoNS, Staphylococcus lugdunensis, has been shown to inhibit S. aureus growth via the production of a novel antibiotic, lugdunin. In this study, we use human skin models to understand the spatial relationships between the CoNS Staphylococcus epidermidis and S. lugdunensis with S. aureus during colonization of human skin. We investigated the attachment patterns of the bacteria, both individually and in competition. Surprisingly, we found that attachment did not always correlate with colonization ability. S. lugdunensis exhibited significantly reduced attachment to human skin stratum corneum but was an efficient longer-term colonizer. S. lugdunensis had a distinct attachment pattern on human corneocytes, with no significant overlap, or competitive exclusion, with the other strains. S. lugdunensis is a potential probiotic strain, with a proven ability to suppress S. aureus. Before this potential can be realized, however, further research is needed to understand how this strain adheres and interacts with other bacteria in the human skin microenvironment.

Spatio-Temporal Change of Skin and Oral Microbiota: A Longitudinal Study of Microbial Diversity and Stability

The human skin and oral cavity harbor complex microbial communities, which exist in dynamic equilibrium with the host's physiological state and the external environment. This study investigates the microbial atlas of human skin and oral cavities using samples collected over a 10-month period, aiming to assess how both internal and external factors influence the human microbiome. We examined bacterial community diversity and stability across various body sites, including palm and nasal skin, saliva, and oral epithelial cells, during environmental changes and a COVID-19 pandemic. The skin microbiome was confirmed to display spatial and temporal stability compared to the oral microbiome, particularly the oral epithelium, which was susceptible to changes in the host's physiological state and immune response. Moreover, significant differences in the microbial community structure among the 4 sample types were observed, and 87 distinct bacteria biomarkers were identified. The random forest prediction model achieved an overall prediction accuracy of 95.24% across the four types of samples studied. Additionally, nasal skin samples showed significant promise for individual identification through profiling the skin microbiota. These findings highlight the potential of skin and oral microbiota as forensic markers for inferring body sites and identifying individuals. In summary, despite facing limitations such as a small cohort size and the need for broader validation, this research provides an overall perspective and initial insights for refining experimental designs and conducting in-depth research in various microbial research fields.

Loss of Cutibacterium is responsible for chronic kidney disease-associated pruritus in patients on dialysis

BACKGROUND

Chronic kidney disease (CKD)-associated pruritus is a severe distressing condition that frequently occurs in patients undergoing dialysis. In this study, the profile of the skin microbiome was analyzed to understand the underlying etiology and potential treatments.

METHODS

Seventy-six end-stage kidney disease (ESKD) patients (hemodialysis, 40; peritoneal dialysis, 36) and 15 healthy controls were enrolled and swabbed at three sites: back, antecubital fossa, and shin. The pruritus severity of the enrolled subjects was validated by the Worst Itch Numeric Rating Scale (WI-NRS), 5-D itch scale, and Uremic Pruritus in Dialysis Patients (UP-Dial). The 16S genebased metagenomics method was applied to skin microbiome analysis.

RESULTS

In the comparison of bacterial communities of ESKD patients and the control group, there was a significant difference on back. Specifically, the average composition ratio of the Cutibacterium in the back samples was significantly lower in ESKD patients than in healthy controls (p < 0.01). In further analysis of ESKD patients, Cutibacterium was significantly lower in the high pruritus group than in the low pruritus group (p < 0.05), even though other clinical parameters such as age, calcium-phosphorus product, and intact parathyroid hormone showed no significance difference between the groups.

CONCLUSION

In ESKD patients, the skin microbiome of the back was significantly altered, and the severity of itching was related to the reduction of Cutibacterium. This research reveals the relationship between skin microbiota and CKD-associated pruritus in multiple skin sites for the first time. The results of this study suggest a potential data basis for the diagnosis and treatment of CKD-associated pruritus.

Males are at higher risk of colonization and infection with multi-drug-resistant organisms than females

BACKGROUND

The global rise in multi-drug-resistant organisms (MDROs) is alarming, and antimicrobial resistance poses a significant public health threat globally. Although certain risk factors are known, including recent antimicrobial therapy, inappropriate use and hospitalization, the focus on gender-specific aspects in MDROs is scarce. The aim of this study was to show gender-specific differences in colonization and infection of multiple MDROs and their detection sites.

METHODS

For this multi-centre, retrospective cohort study, surveillance data were collected between 2015 and 2020 from 86 hospitals from Helios Kliniken, Germany. The following multi-drug-resistant bacteria were analysed by sample site: meticillin-resistant Staphylococcus aureus (MRSA); Enterococcus spp.; Escherichia coli; Klebsiella pneumoniae; Pseudomonas aeruginosa; and Acinetobacter baumannii.

RESULTS

Of the 7,081,708 cases in the database, 187,656 patients were found to be colonized with MDROs (2.65%). A documented infection with an MDRO was identified in 33,023 patients (0.466%), with the origin of infection known in 24,231 cases. Male gender was a risk factor for both infection and colonization with any MDRO (P<0.001). Males exhibited a higher likelihood of MDRO detection in superficial skin/soft tissue, blood cultures (P<0.001) and respiratory samples (P=0.002). Additionally, gender-specific differences in MDRO detection site and pathogens were found, with a slightly higher proportion of MRSA infections in deep skin/soft tissue and respiratory samples for females.

CONCLUSIONS

This study reinforces the existing hypothesis that male gender is a risk factor for colonization and infection with MDROs, supported by a large dataset. This highlights the need to acknowledge gender-specific MDRO susceptibility in clinical practice.

A structural equation model predicts chronic wound healing time using patient characteristics and wound microbiome composition

Wound aetiology, host characteristics and the wound microbiome contribute to chronic wound development. Yet, there is little accounting for the relative importance of these factors to predict wound healing. Here, a structural equation model was developed to provide such an explanatory and predictive framework. Chronic wounds from 565 patients treated at a clinic practicing biofilm-based wound care were included. Patient information included DNA sequencing-based wound microbiome clinical reports corresponding to the initial clinical visit. Wound microbiome data was integrated into the SEM as a latent variable using a pre-modelling parcel optimization routine presented herein for the first time (available as R library parcelR). A microbiome latent construct associated with improved healing was validated, and the final SEM included this latent construct plus three species associated with diminished healing (Anaerococcus vaginalis, Finegoldia magna and Pseudomonas aeruginosa), as well as smoking, wound volume, slough, exudate, edema, percent granulation and wound etiology. This model explained 46% of variations in healing time, with the microbiome contributing the largest proportion of variance explained. Model validity was confirmed with an independent cohort (n = 79) through which ~60% of the variation in healing time was predicted. This model can serve as a foundation for the development of a predictive tool that may have clinical utility.

Efficacy of Various Dry Electrode-Based ECG Sensors: A Review

Long-term electrocardiogram (ECG) monitoring is crucial for detecting and diagnosing cardiovascular diseases (CVDs). Monitoring cardiac health and activities using efficient, noninvasive, and cost-effective techniques such as ECG can be vital for the early detection of different CVDs. Wet electrode-based traditional ECG techniques come with unavoidable limitations of the altered quality of ECG signals caused by gel volatilization and unwanted noise followed by dermatitis. The limitation related to the wet electrodes for long-term ECG monitoring in static and dynamic postures reminds us of the urgency of a suitable substitute. Dry electrodes promise long-term ECG monitoring with the potential for significant noise reduction. This review discusses traditional and alternative techniques to record ECG in terms of meeting the efficient detection of CVDs by conducting a detailed analysis of different types of dry electrodes along with materials (substrate, support, matrix, and conductive part) used for fabrication, followed by the number of human subjects they have been used for validation. The degradation of these electrodes has also been discussed briefly. This review finds a need for more validation on a sufficient number of subjects and the issue of cost and noise hindering the commercialization of these dry electrodes.

Dysbiosis of the human skin mycobiome in patients receiving systemic IL-23 inhibitors

BACKGROUND

Systemic inhibition of pro-inflammatory cytokines affects the skin microbiome; however, the impact of systemic anti-inflammatory therapy on the skin fungal microbiome is poorly understood. To examine the effects of cytokine inhibition on the fungal community on human skin and oral mucosa, we analyzed the composition of the skin mycobiome before and after IL-23 inhibition.

METHODS

The study enrolled 15 psoriasis patients. Swab samples were collected from the psoriasis-free skin of antecubital fossa, post-auricular, and the tongue surface before and after 16 weeks of treatment with anti-IL-23 antibodies. Fungal DNA was sequenced by ITS1 metagenomic analysis, and taxonomic classification was performed.

RESULTS

Data from samples collected from the antecubital fossa revealed that the α diversity of the skin mycobiome decreased significantly after treatment with anti-IL-23 antibodies (p = 0.0120). Fungal DNAs were not amplified in 6/15 swab samples after 16 weeks of IL-23 inhibition; by contrast, sufficiently detected in all 15 samples before treatment (p = 0.0554). A comparison of 9/15 paired samples containing well-detected reads revealed that the percentage of genus Malassezia in the mycobiome fell significantly after treatment with IL-23 inhibitors (before, 29.3% ± 9.9%; after; 8.5% ± 3.4%, p = 0.0137). The mycobiome on post-auricular skin and on the tongue surface showed no marked changes after IL-23 inhibition.

CONCLUSIONS

Taken together, the data suggest that inhibition of systemic IL-23 provokes dysbiosis of the mycobiome at the antecubital fossa skin, a finding characterized by reduced fungal diversity and a reduction in the percentage of the genus Malassezia.

Effect of Skin Barrier on Atopic Dermatitis

The skin acts as the body's primary physical and immune barrier, maintaining the skin microbiome and providing a physical, chemical, and immune barrier. A disrupted skin barrier plays a critical role in the onset and advancement of inflammatory skin conditions such as atopic dermatitis (AD) and contact dermatitis. This narrative review outlines the relationship between AD and skin barrier function in preparation for the search for possible markers for the treatment of AD.

Bat Cutaneous Microbial Assemblage Functional Redundancy Across a Host-Mediated Disturbance

Understanding the processes and factors that influence the structure of host-associated microbial assemblages has been a major area of research as these assemblages play a role in host defense against pathogens. Previous work has found that bacterial taxa within bat cutaneous microbial assemblages have antifungal capabilities against the emerging fungal pathogen, Pseudogymnoascus destructans. However, our understanding of natural fluctuations in these cutaneous microbial assemblages over time due to shifts in host habitat is lacking. The objective of this work was to understand how the taxonomic and functional bat cutaneous microbial assemblage responds to seasonal shifts in host habitat. We hypothesized that at the community level, there will be turnover in taxonomic structure but functional redundancy across seasons. On a finer scale, we hypothesized that there will be differences in the relative abundance of functional genes that code for select pathways across seasons. Results showed that, on a broad scale, the bat cutaneous microbial assemblage is seasonally taxonomically dynamic but functionally redundant. Additionally, although there was almost complete taxonomic turnover between winter and summer bat microbial assemblages, there was no difference in assemblage structure across winters. This functional redundancy was also observed at finer scales, with no differences in the abundance of genes within pathways of hypothesized importance across seasons or winters. Taken together, results suggest species sorting mechanisms correlated with shifts in host habitat use, drive taxonomic but not functional host-associated cutaneous microbial community assembly.