The human skin microbiome

Assessment of peripheral venous catheters microbiota and its association with phlebitis

BACKGROUND

Peripheral venous catheters (PVCs) remain the primary mode of short-term venous access for managing intravenous fluid, obtaining blood samples, and peripheral parenteral nutrition. They may get contaminated and require regular monitoring to prevent complications. This study evaluated the occurrence of phlebitis and its associated-clinical and microbiological indicators.

METHODS

The frequency of phlebitis was evaluated in hospitalized patients of both medical and surgical fields. Subsequently, the dichotomous association between the presence of phlebitis and the clinical aspects was investigated. In parallel, the bacterial contamination of PVCs was assessed through culture-based methods, microscopy observation, and 16S rRNA gene sequencing.

RESULTS

Approximately one in four patients presented phlebitis (28.4%). The most frequent symptom was erythema at access site, with or without pain, corresponding to Score 1 on the phlebitis scale (17.9%). Colonization of both lumen and external surface of PVC was observed in 31.3% of the samples. Staphylococcus and Pseudomonas were the most isolated bacterial genera on the PVC surface. No significant association was observed between the presence of phlebitis and the clinical aspects, as well as the presence of microorganisms.

CONCLUSION

Microorganism were present on both internal and external PVC surface, without being associated to phlebitis.

The prebiotic effects of fructooligosaccharides enhance the growth characteristics of Staphylococcus epidermidis and enhance the inhibition of Staphylococcus aureus biofilm formation

OBJECTIVE

Oligosaccharides have been shown to enhance the production of short chain fatty acids (SCFAs) by gut probiotics and regulate gut microbiota, to improve intestinal health. Recent research indicates that oligosaccharides may also positively impact skin microbiota by selectively promoting the growth of skin commensal bacteria and inhibiting pathogenic bacteria. However, the specific metabolic and regulatory mechanisms of skin commensal bacteria in response to oligosaccharides remain unclear. This study aims to explore the influence of four oligosaccharides on the growth and metabolism of Staphylococcus epidermidis and further identify skin prebiotics that can enhance its probiotic effects on the skin.

METHODS

Fructooligosaccharides (FOS), isomaltooligosaccharide (IMO), galactooligosaccharides (GOS) and inulin were compared in terms of their impact on cell proliferation, SCFAs production of S. epidermidis CCSM0287 and the biofilm inhibition effect of their fermentation supernatants on Staphylococcus aureus CCSM0424. Furthermore, the effect of FOS on S. epidermidis CCSM0287 was analysed by the transcriptome analysis.

RESULTS

All four oligosaccharides effectively promoted the growth of S. epidermidis CCSM0287 cells, increased the production of SCFAs, with FOS demonstrating the most significant effect. Analysis of the SCFAs indicated that S. epidermidis CCSM0287 predominantly employs oligosaccharides to produce acetic acid and isovaleric acid, differing from the SCFAs produced by gut microbiota. Among the four oligosaccharides, the addition of 2% FOS fermentation supernatant significantly inhibited S. aureus CCSM0424 biofilm formation. Furthermore, RNA sequencing revealed 162 differentially expressed genes (84 upregulated and 78 downregulated) of S. epidermidis CCSM0287 upon FOS treatment compared with glucose treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis highlighted differences in the amino acid synthesis pathway, particularly in terms of arginine biosynthesis.

CONCLUSION

FOS promotes cell proliferation, increases the SCFA production of S. epidermidis CCSM0287 and enhance the inhibition of S. aureus biofilm formation, suggesting that FOS serves as a potential prebiotic for strain S. epidermidis CCSM0287.

Network pharmacology, transcriptomics, and biological validation reveal a lipid secretion inhibitory and anti-inflammatory mechanism of tanreqing gel in the treatment of acne

ETHNOPHARMACOLOGICAL RELEVANCE

Acne vulgaris is a common skin disease affecting the pilosebaceous unit, in which abnormal sebum secretion and inflammation play crucial roles. The traditional Chinese medicine Tanreqing has been utilized in dermatology to effectively treat various diseases. However, its effects and underlying mechanisms in acne vulgaris remain unclear.

AIM OF THE STUDY

This study aims to assess the potential benefits of Tanreqing gel (TRQ) in acne treatment and to explore the mechanisms by which TRQ inhibits sebum secretion and reduces inflammation.

MATERIALS AND METHODS

A mouse model of acne induced by Cutibacterium acnes (C. acnes) was established. The impact of TRQ on acne lesions was assessed using optical imaging and histopathology. Network pharmacology and transcriptomics were used to identify significant intervention pathways and targets. Both in vivo and in vitro experiments were conducted to detect the expression of genes and proteins associated with inflammation and sebum metabolism.

RESULTS

TRQ significantly improved pathological changes in the lesion areas of mice, such as redness, vascular dilation, and increased blood flow. It also reduced inflammatory cell infiltration in the dermis and inhibited the accumulation of lipids in the sebaceous glands. Network pharmacology analysis indicated that TRQ might exert anti-inflammatory effects through the IL-17, TOLL-like receptor, and NF-κB signaling pathways. The transcriptomic analysis confirmed the importance of these pathways in the C. acnes-induced acne model. Furthermore, TRQ was found to reduce sebum secretion by inhibiting fatty acid biosynthesis through the suppression of proteins in the PI3K-Akt signaling pathway. Cell experiments confirmed that TRQ could suppress the release of inflammatory factors induced by C. acnes surface structure peptidoglycan (PGN) and metabolite porphyrins. Additionally, it was observed to reverse the elevated porphyrin secretion associated with abnormal sebum production, ultimately relieving acne inflammation.

CONCLUSION

This study demonstrated that TRQ effectively alleviates C. acnes-induced acne symptoms by inhibiting sebum secretion and inflammatory responses through multiple pathways and targets. It provides new insights and directions for acne treatment.

Comparative analysis of the human microbiome from four different regions of China and machine learning-based geographical inference

The human microbiome, the community of microorganisms that reside on and inside the human body, is critically important for health and disease. However, it is influenced by various factors and may vary among individuals residing in distinct geographic regions. In this study, 220 samples, consisting of sterile swabs from palmar skin and oral and nasal cavities were collected from Chinese Han individuals living in Shanghai, Chifeng, Kunming, and Urumqi, representing the geographic regions of east, northeast, southwest, and northwest China. The full-length 16S rRNA gene of the microbiota in each sample was sequenced using the PacBio single-molecule real-time sequencing platform, followed by clustering the sequences into operational taxonomic units (OTUs). The analysis revealed significant differences in microbial communities among the four regions. Cutibacterium was the most abundant bacterium in palmar samples from Shanghai and Kunming, Psychrobacter in Chifeng samples, and Psychrobacillus in Urumqi samples. Additionally, Streptococcus and Staphylococcus were the dominant bacteria in the oral and nasal cavities. Individuals from the four regions could be distinguished and predicted based on a model constructed using the random forest algorithm, with the predictive effect of palmar microbiota being better than that of oral and nasal cavities. The prediction accuracy using hypervariable regions (V3-V4 and V4-V5) was comparable with that of using the entire 16S rRNA. Overall, our study highlights the distinctiveness of the human microbiome in individuals living in these four regions. Furthermore, the microbiome can serve as a biomarker for geographic origin inference, which has immense application value in forensic science.IMPORTANCEMicrobial communities in human hosts play a significant role in health and disease, varying in species, quantity, and composition due to factors such as gender, ethnicity, health status, lifestyle, and living environment. The characteristics of microbial composition at various body sites of individuals from different regions remain largely unexplored. This study utilized single-molecule real-time sequencing technology to detect the entire 16S rRNA gene of bacteria residing in the palmar skin, oral, and nasal cavities of Han individuals from four regions in China. The composition and structure of the bacteria at these three body sites were well characterized and found to differ regionally. The results elucidate the differences in bacterial communities colonizing these body sites across different regions and reveal the influence of geographical factors on human bacteria. These findings not only contribute to a deeper understanding of the diversity and geographical distribution of human bacteria but also enrich the microbiome data of the Asian population for further studies.

Microbiome analysis in individuals with human papillomavirus oral infection

Microbiome gained attention as a cofactor in cancers originating from epithelial tissues. High-risk (hr)HPV infection causes oropharyngeal squamous cell carcinoma but only in a fraction of hrHPV+ individuals, suggesting that other factors play a role in cancer development. We investigated oral microbiome in cancer-free subjects harboring hrHPV oral infection (n = 33) and matched HPV- controls (n = 30). DNA purified from oral rinse-and-gargles of HIV-infected (HIV+) and HIV-uninfected (HIV-) individuals were used for 16S rRNA gene V3-V4 region amplification and sequencing. Analysis of differential microbial abundance and differential pathway abundance was performed, separately for HIV+ and HIV- individuals. Significant differences in alpha (Chao-1 and Shannon indices) and beta diversity (unweighted UniFrac distance) were observed between hrHPV+ and HPV-negative subjects, but only for the HIV- individuals. Infection by hrHPVs was associated with significant changes in the abundance of Saccharibacteria in HIV+ and Gracilibacteria in HIV- subjects. At the genus level, the greatest change in HIV+ individuals was observed for Bulleidia, which was significantly enriched in hrHPV+ subjects. In HIV- individuals, those hrHPV+ showed a significant enrichment of Parvimonas and depletion of Alloscardovia. Our data suggest a possible interplay between hrHPV infection and oral microbiome, which may vary with the HIV status.

Living Microneedles for Intradermal Delivery of Beneficial Bacteria

The skin, our first line of defense against external threats, combines a physical barrier and a rich microbial community. Disruptions of this community, for example, due to infectious injury, have been linked to a decrease in bacteria diversity and to mild to severe pathological conditions. Although some progress has been made in the field, possibilities/procedures for restoring the skin microbiome are still far from ideal. The objective of this study was to design and evaluate a dissolvable poly(vinyl alcohol)/polyvinylpyrrolidone microneedle (MN) patch containing live Bacillus subtilis. According to the plan, bacteria were distributed equally throughout the patch without compromising the morphology and mechanical properties of the needles. B. subtilis was successfully released from the MNs, reaching a logarithmic growth phase after 5 h. These MNs demonstrated remarkable antibacterial activity against the Gram-positive pathogenic S. pyogenes, S. aureus, and C. acnes, while the empty control MNs showed no such activity. Finally, mice were inserted with a single MN patch loaded with GFP-B. subtilis presented significantly higher total radiance efficiency (TRE) values compared to the empty-MN mice throughout the entire experiment. This concept of incorporating live, secreting bacteria within a supportive MN patch shows great promise as a bacterial delivery system, offering a potential shift from conventional pharmacological approaches to more sustainable and symbiotic therapies.

Commensal-derived tryptophan metabolites fortify the skin barrier: Insights from a 50-species gnotobiotic model of human skin microbiome

The epidermal barrier defends the body against dehydration and harmful substances. The commensal microbiota is essential for proper differentiation and repair of the epidermal barrier, an effect mediated by the aryl hydrocarbon receptor (AHR). However, the microbial mechanisms of AHR activation in skin are less understood. Tryptophan metabolites are AHR ligands that can be products of microbial metabolism. To identify microbially regulated tryptophan metabolites in vivo, we established a gnotobiotic model colonized with fifty human skin commensals and performed targeted mass spectrometry on murine skin. Indole-related metabolites were enriched in colonized skin compared to germ-free skin. In reconstructed human epidermis and in murine models of atopic-like barrier damage, these metabolites improved barrier repair and function individually and as a cocktail. These results provide a framework for the identification of microbial metabolites that mediate specific host functions, which can guide the development of microbe-based therapies for skin disorders.

Global burden of bacterial skin diseases from 1990 to 2045: an analysis based on global burden disease data

Bacterial skin diseases are a category of inflammatory skin conditions caused by bacterial infections, which impose a significant global disease burden. However, they have not been well assessed or predicted on a global scale. It is necessary to update the estimates and forecast future trends of the global burden of bacterial skin diseases to evaluate the impact of past healthcare policies and to provide guidance and information for new national and international healthcare strategies. We aimed to describe the burden and trend of bacterial skin diseases and to predict the burden up to 2045. To achieve this, we employed a cross-sectional analysis based on Global Burden of Disease (GBD) data, utilizing advanced statistical models to quantify trends and forecast future burdens. Data on incidence and disability-adjusted life years (DALYs) of bacterial skin diseases were obtained from Global Burden of Disease 2021. We used average annual percent change (AAPC) by Joinpoint Regression to quantify the temporal trends. We conducted decomposition analysis to understand the contribution of aging, epidemiological changes, and population growth. Bayesian Age-Period-Cohort model was used to predict burden up to 2045. Global incidence rate of bacterial skin diseases increased from 8,988.74 per 100,000 in 1990 to 10,823.88 per 100,000, with AAPC of 0.62% (0.61 ~ 0.63%). The highest incidence rate was in low Socio-demographic Index (SDI) region and population aged < 35. The DALYs rate increased from 20.82 per 100,000 in 1990 to 25.45 per 100,000 in 2021, with AAPC of -0.11% (-0.34 ~ 0.13%). The highest increase of DALYs was in high SDI region and population aged > 85. Among the three evaluated factors of decomposition analysis, the major drivers of incident case rise were population growth, followed by epidemiological changes; the major drivers of DALYs case rise were population growth, followed by aging. The number of incidence cases has increased since 1990, reaching nearly 90 million in 2021 and expected to hit 1.2 billion in 2045. The incidence rate has also risen. Meanwhile, DALYs showed an upward trend from 1990 to 2005, peaking at 32/100,000, then a downward trend. Our findings align with our initial objectives, demonstrating a significant increase in the global incidence of bacterial skin diseases and highlighting the need for targeted prevention and treatment strategies. The variation in burden across different regions and age groups underscores the importance of tailored public health interventions. Predictive models suggest a continued rise in incidence rates and incident cases through 2045, emphasizing the urgency for action. This study provides a foundation for future research and policy development aimed at reducing the burden of bacterial skin diseases worldwide.

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.

Fungal quorum sensing molecules as potential drugs in the treatment of chronic wounds and their delivery

INTRODUCTION

Chronic non-healing wounds have emerged as a significant global healthcare challenge. Biofilm induced wound infections has been widely acknowledged. Despite the advanced understanding of biofilm formation, the existing approaches for diagnosing biofilms in wounds remain considerably suboptimal. Chemical signals produced by fungi to sense their environment, known as quorum sensing (QS) molecules are anticipated to cause revolution in non-healing wound antisepsis.

AREAS COVERED

Biofilms render chronic wounds resistant to treatment and impede tissue repair by inducing chronic inflammation. QS is a biochemical signaling pathway that involves certain secreted molecules, namely phenylethanoids, indolyl, and sesquiterpene alcohols that can significantly minimize and obliterate bacterial biofilms if properly applied and released in wound treatments.

EXPERT OPINION

QS molecules (QSMs) possess inhibitory properties that obstruct the formation of microbial biofilms and exhibit synergism with common antimicrobials. They can disrupt biofilms formed by drug-resistant microorganisms. The understanding of the current mechanisms and advancements in the utilization of QSMs within diverse drug delivery systems, and their release dynamics will be crucial in new drug design and delivery. Exploration of co-delivery of drugs alongside QS molecules, and assessing their impact on healing of chronic wounds before moving to clinical trials remain unaddressed.

Skin microbiota: pathogenic roles and implications in atopic dermatitis

Atopic dermatitis (AD) is a chronic and inflammatory skin disorder characterized by impaired barrier function and imbalanced immunity. Recent advances have revealed that dysbiosis of skin microbiota plays important roles in the pathogenesis and development of AD. Meanwhile, endogenous and external factors contribute to the dysbiosis of skin microbiota in AD. Additionally, various treatments, including topical treatments, phototherapy, and systemic biologics, have demonstrated positive impacts on the clinical outcomes, alongside with the modulations of cutaneous microbiota in AD patients. Importantly, therapeutics or products regulating skin microbiota homeostasis have demonstrated potential for AD treatment in early clinical studies. In this review, we underline changes of the skin microbiota correlated with AD. Meanwhile, we provide an overview of the skin microbiota regarding its roles in the pathogenesis and development of AD. Finally, we summarize therapeutic strategies restoring the skin microbial homeostasis in AD management.

Life stage impact on the human skin ecosystem: lipids and the microbial community

Sebaceous free fatty acids are metabolized by multiple skin microbes into bioactive lipid mediators termed oxylipins. This study investigated correlations between skin oxylipins and microbes on the superficial skin of pre-pubescent children (N = 36) and adults (N = 100), including pre- (N = 25) and post-menopausal females (N = 25). Lipidomics and metagenomics revealed that Malassezia restricta positively correlated with the oxylipin 9,10-DiHOME on adult skin and negatively correlated with its precursor, 9,10-EpOME, on pre-pubescent skin. Co-culturing Malassezia with keratinocytes demonstrated a link between 9,10-DiHOME and pro-inflammatory cytokines IL-1β and IL-6 production. We also observed strong correlations between other skin oxylipins and microbial taxa, highlighting life stage differences in sebum production and microbial community composition. Our findings imply a complex host-microbe communication system mediated by lipid metabolism occurring on human skin, warranting further research into its role in skin health and disease and paving the way towards novel therapeutic targets and treatments.

Challenges and considerations in liposomal hydrogels for the treatment of infection

INTRODUCTION

Liposomal hydrogels are novel drug delivery systems that comprise preformed liposomes incorporated in hydrogels destined for mostly localized drug therapy, herewith antimicrobial therapy. The formulation benefits from versatility of liposomes as lipid-based nanocarriers that enable delivery of various antimicrobials of different lipophilicities, and secondary vehicle, hydrogel, that assures better retention time of formulation at the infection site. Especially in an era of alarming antimicrobial resistance, efficient localized antimicrobial therapy that avoids systemic exposure of antimicrobial and related side effects is crucial.

AREAS COVERED

We provide an overview of liposomal hydrogels that were developed for superior delivery of antimicrobials at different infections sites, with focus on skin and vaginal infections. The review summarizes the challenges of infection site and most common infection-causing pathogens and offers commentary on most relevant features the formulation needs to optimize to increase the therapy outcome. We discuss the impact of liposomal composition, size, and choice of polymer-forming hydrogel on antimicrobial outcome based on the literature overview and own experience in the field.

EXPERT OPINION

Liposomal hydrogels offer improved therapy outcome in localized antimicrobial therapy. By fine-tuning of liposomal as well as hydrogel properties, formulations with superior performance can be optimized targeting specific infection site.

Emerging Concepts in Periprosthetic Joint Infection Research: The Human Microbiome

Microorganisms, including bacteria, fungi, and viruses, that reside on and within the human body are collectively known as the human microbiome. Dysbiosis, or disruption in the microbiome, has been implicated in several disease processes, including asthma, obesity, autoimmune diseases, and numerous other conditions. While the Human Microbiome Project (HMP) and the generation of descriptive studies it inspired established correlations between characteristic patterns in the composition of the microbiome and specific disease phenotypes, current research has begun to focus on elucidating the causal role of the microbiome in disease pathogenesis. Within the field of orthopaedic surgery, researchers have proposed the concept of a "gut-joint axis" by which the intestinal microbiome influences joint health and the development of diseases such as osteoarthritis and periprosthetic joint infection (PJI). It is theorized that intestinal dysbiosis increases gut permeability, leading to the translocation of bacteria and their metabolic products into the systemic circulation and the stimulation of proinflammatory response cascades throughout the body, including within the joints. While correlative studies have identified patterns of dysbiotic derangement associated with osteoarthritis and PJI, translational research is needed to clarify the precise mechanisms by which these changes influence disease processes. Additionally, an emerging body of literature has challenged the previously held belief that certain body sites are sterile and do not possess a microbiome, with studies identifying distinct microbial genomic signatures and a core microbiome that varies between anatomic sites. A more thorough characterization of the joint microbiome may have profound implications for our understanding of PJI pathogenesis and our ability to stratify patients based on risk. The purpose of this review was to outline our current understanding of the human microbiome, to describe the gut-joint axis and its role in specific pathologies, including PJI, and to highlight the potential of microbiome-based therapeutic interventions in the field of orthopaedics.

Droplet microfluidics: unveiling the hidden complexity of the human microbiome

The human body harbors diverse microbial communities essential for maintaining health and influencing disease processes. Droplet microfluidics, a precise and high-throughput platform for manipulating microscale droplets, has become vital in advancing microbiome research. This review introduces the foundational principles of droplet microfluidics, its operational capabilities, and wide-ranging applications. We emphasize its role in enhancing single-cell sequencing technologies, particularly genome and RNA sequencing, transforming our understanding of microbial diversity, gene expression, and community dynamics. We explore its critical function in isolating and cultivating traditionally unculturable microbes and investigating microbial activity and interactions, facilitating deeper insight into community behavior and metabolic functions. Lastly, we highlight its broader applications in microbial analysis and its potential to revolutionize human health research by driving innovations in diagnostics, therapeutic development, and personalized medicine. This review provides a comprehensive overview of droplet microfluidics' impact on microbiome research, underscoring its potential to transform our understanding of microbial dynamics and their relevance to health and disease.

Epigenetic Regulatory Processes Involved in the Establishment and Maintenance of Skin Homeostasis-The Role of Microbiota

Epigenetic mechanisms are central to the regulation of all biological processes. This manuscript reviews the current understanding of diverse epigenetic modifications and their role in the establishment and maintenance of normal skin functions. In healthy skin, these mechanisms allow for the precise control of gene expression, facilitating the dynamic balance between cell proliferation and differentiation necessary for effective barrier function. Furthermore, as the skin ages, alterations in epigenetic marks can lead to impaired regenerative capacity and increased susceptibility to environmental stressors. The interaction between skin microbiota and epigenetic regulation will also be explored, highlighting how microbial communities can influence skin health by modulating the host gene expression. Future research should focus on the development of targeted interventions to promote skin development, resilience, and longevity, even in an ever-changing environment. This underscores the need for integrative approaches to study these complex regulatory networks.

Perturbations in the gut microbiome of C57BL/6 mice by the sobriety aid Antabuse® (disulfiram)

AIMS

Disulfiram (Antabuse®) is an oral alcohol sobriety medication that exhibits antimicrobial activity against Gram-positive facultative anaerobes. The aims of this study were to measure the antimicrobial activity against anaerobic bacteria of the gut human microbiome and establish the extent that disulfiram alters the microbial composition of the ileum, cecum, and feces using C57BL/6 mice.

METHODS AND RESULTS

Antimicrobial susceptibility testing by the microdilution method revealed that disulfiram inhibits the in vitro growth of gut anaerobic species of Bacteroides, Clostridium, Peptostreptococcus, and Porphyromonas. Differential sequencing of 16S rRNA isolated from the ileum, cecum, and feces contents of treated vs. untreated mice showed that disulfiram enriches the Gram-negative enteric population. In female mice, the enrichment was greatest in the ileum, whereas the feces composition in male mice was the most heavily altered.

CONCLUSIONS

Daily administration of oral disulfiram depletes the enteric Gram-positive anaerobe population as predicted by the minimum inhibitory concentration data for isolates from the human gut microbiota.

Investigating the causal relationship between skin microbiota and hypertrophic scar using bidirectional mendelian randomization

BACKGROUND

Hypertrophic scar (HS) is acknowledged as a pathological fibro-proliferative disease of the dermis, resulting from excessive connective tissue growth. HS significantly impacts patient quality of life due to both social and functional issues. Despite various treatments, therapeutic effectiveness remains limited, necessitating further exploration of underlying factors and mechanisms.

OBJECTIVE

The current study was designed to determine the causal relationship between skin microbiota and HS employing a bidirectional Mendelian randomization (MR) approach.

METHODS

We utilized genome-wide association study (GWAS) data from the PopGen cohort and the FinnGen database. Independent single nucleotide polymorphisms (SNPs) linked to the skin microbiota were identified as instrumental variables (IVs) chosen for the two-sample MR analysis. Key analytical approaches included inverse variance weighting (IVW), MR-Egger, simple median, simple mode, and weighted mode, with MR-Egger intercept test and Cochrane's Q test used to detect potential horizontal pleiotropy and heterogeneity.

RESULTS

The two-sample MR analysis identified significant causal relationships between specific skin microbiota features and HS. Notably, Enhydrobacter, Micrococcus, and Acinetobacter on moist skin exhibited protective effects against HS, whereas Finegoldia and Lactobacillales on dry skin were linked to an increased risk of HS. Sensitivity analyses verified the strength of these results, revealing no notable horizontal pleiotropy or heterogeneity.

CONCLUSION

Our research reveals a unidirectional causal relationship between certain skin microbiota and HS, suggesting that modulation of skin microbiota could be a novel therapeutic approach for HS management. These results emphasize the significance of considering skin microbiota in the pathogenesis and treatment of HS.

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.

Microbiome and Hemato-immune Aging

The microbiome is a highly complex and diverse symbiotic component that undergoes dynamic changes with the organismal aging. Microbial perturbations, termed dysbiosis, exert strong influence on dysregulating the bone marrow niche and subsequently promoting the aging of hematopoietic and immune system. Accumulating studies have revealed the substantial impact of intestinal microbiome on the initiation and progression of age-related hematologic alteration and diseases, such as clonal hematopoiesis and blood cancers. Current therapeutic approaches to restore the altered microbiome diversity target specific pathobionts and are demonstrated to improve clinical outcomes of antihematologic malignancy treatments. In this review, we discuss the interplay between the microbiome and the hemato-immune system during aging process. We also shed light on the emerging therapeutic strategies to tackle the dysbiosis for amelioration of aging and disease progression.

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.

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.

Effects of Commonly Used Vegetable Oils on Skin Barrier Function and Staphylococcus aureus Biofilm

Adding of vegetable oils to skincare products or the use of plant oils for oil care is a current trend. Therefore, the safety and functionality of vegetable oils are of great concern to consumers and cosmetics manufacturers. This study focused on three types of vegetable oils: sunflower oil (SO), andiroba oil (AO) and hydrogenated olive oil (HOO). We conducted a comprehensive evaluation of the oils, which encompassed their ability to protect mouse skin keratinocytes (XB-2) and mouse fibroblasts (NIH 3T3) from damage caused by the surfactant sodium lauryl sulfate (SLS), their influence on the levels of filaggrin and collagen, their potential to aid in wound healing, and their effectiveness in anti-Staphylococcus aureus biofilm formation. The results showed that SO, AO and HOO at a concentration of 1.5 × 10-4 % (v/v) have the ability to defend against SLS-induced cell damage, increase wound healing ability and the filaggrin and collagen content to XB-2 or NIH 3T3 cells. SO, AO and HOO at a concentration of 3.75 × 10-3 % also have the anti-biofilm ability. Among the oils, AO can inhibit S. aureus biofilm composed of either polysaccharides or proteins. Therefore, the tested vegetable oils and can be applied to the cosmetics field as ingredients to repair damaged skin and preserve skin barrier stability.

The relationship between indoor airborne culturable bacteria with passenger flow in 132 traffic stations during 2019-2020, China

This study aims to provide technical support for the development of a rational administration strategy for indoor environment and passenger flow of stations. The analysis was conducted monitor data of long distance bus stations and train/high speed railway stations from the National project. The monitor and surveyed data included indoor airborne culturable bacteria (IAB), passenger flow, area and height of stations. Data analysis involved the use of paired non-parametric tests, correlation analysis, and mixed linear regression methods. A total of 132 pairs of stations were examined in this study. Additionally, significant variations were observed in the monitoring results for the IAB and passenger flow between 2019 and 2020 (p < 0.05). Specifically, the median values of these two factors in 2020 decreased by 50.52% and 48.33%, respectively, compared to 2019. (p < 0.05). A positive relationship between the daily average passenger flow and the IAB in long distance bus stations and train stations, particularly pronounced with medium sized waiting rooms, which located in subtropical cities with a general level of economic development. The mixed effect regression analysis revealed a significant association between passenger flow (OR = 1.564, 1.288-1.898), per capita volume (OR = 0.856, 0.733-0.998), and per capita area (OR = 0.806, 0.678-0.956) with the IAB (p < 0.05) just in long distance bus stations. It is crucial to regulate passenger flow and per capita area in the waiting room of long distance bus stations to mitigate the spread of airborne culturable bacteria during infectious disease epidemics.

An Overview of the Skin Microbiome, the Potential for Pathogen Shift, and Dysbiosis in Common Skin Pathologies

Recent interest in the diverse ecosystem of bacteria, fungi, parasites, and viruses that make up the skin microbiome has led to several studies investigating the microbiome in healthy skin and in a variety of dermatological conditions. An imbalance of the normal skin flora can cause some skin diseases, and current culture techniques are often unable to detect a microorganism to further our understanding of the clinical-microbiological correlates of disease and dysbiosis. Atopic dermatitis and rosacea are presentations that GPs often manage that may have an infective or microbiological component and can be challenging to treat. We aim to discuss the implications of the skin microbiome including the impact of dysbiosis on conditions such as these. We will also discuss some clinical pearls for initial and future directions of the management of conditions such as atopic dermatitis, rosacea, and hidradenitis suppurativa. Further research using culture-independent techniques is needed for conditions involving microbial dysbiosis to advance our knowledge of skin disease pathophysiology and guide future management.

Interactions with alloparents are associated with the diversity of infant skin and fecal bacterial communities in Chicago, United States

INTRODUCTION

Social interactions shape the infant microbiome by providing opportunities for caregivers to spread bacteria through physical contact. With most research focused on the impact of maternal-infant contact on the infant gut microbiome, it is unclear how alloparents (i.e., caregivers other than the parents) influence the bacterial communities of infant body sites that are frequently contacted during bouts of caregiving, including the skin.

METHODS

To begin to understand how allocare may influence the diversity of the infant microbiome, detailed questionnaire data on infant-alloparent relationships and specific allocare behaviors were coupled with skin and fecal microbiome samples (four body sites) from 48 infants living in Chicago, United States.

RESULTS

Data from 16S rRNA gene amplicon sequencing indicated that infant skin and fecal bacterial diversity showed strong associations (positive and negative) to having female adult alloparents. Alloparental feeding and co-sleeping displayed stronger associations to infant bacterial diversity compared to playing or holding. The associations with allocare behaviors differed in magnitude and direction across infant body sites. Bacterial relative abundances varied by infant-alloparent relationship and breastfeeding status.

CONCLUSION

This study provides some of the first evidence of an association between allocare and infant skin and fecal bacterial diversity. The results suggest that infants' exposure to bacteria from the social environment may vary based on infant-alloparent relationships and allocare behaviors. Since the microbiome influences immune system development, variation in allocare that impacts the diversity of infant bacterial communities may be an underexplored dimension of the social determinants of health in early life.

Lipidic drug delivery systems are responsive to the human microbiome

In vitro and in vivo tests for therapeutic agents are typically conducted in sterile environments, but many target areas for drug delivery are home to thousands of microbial species. Here, we examine the behaviour of lipidic nanomaterials after exposure to representative strains of four bacterial species found in the gastrointestinal tract and skin. Small angle X-ray scattering measurements show that the nanostructure of monoolein cubic and inverse hexagonal phases are transformed, respectively, into inverse hexagonal and inverse micellar cubic phases upon exposure to a strain of live Staphylococcus aureus often present on skin and mucosa. Further investigation demonstrates that enzymatic hydrolysis and cell membrane lipid transfer are both likely responsible for this effect. The structural responses to S. aureus are rapid and significantly reduce the rate of drug release from monoolein-based nanomaterials. These findings are the first to demonstrate how a key species in the live human microbiome can trigger changes in the structure and drug release properties of lipidic nanomaterials. The effect appears to be strain specific, varies from patient to patient and body region to body region, and is anticipated to affect the bioapplication of monoglyceride-based formulations.

Fungal influence on immune cells and inflammatory responses in the tumor microenvironment (Review)

In recent years, a growing body of research has highlighted the significant influence of the microbiota on tumor immunity within the tumor microenvironment (TME). While much attention has been given to bacteria, emerging evidence suggests that fungi also play crucial roles in tumor development. The present review aimed to consolidate the latest findings on the mechanisms governing the interactions between fungi and the immune system or TME. By elucidating these intricate mechanisms, novel insights into the modulation of tumor immunity and therapeutic strategies may be uncovered. Ultimately, a deeper understanding of the interplay between fungi and the TME holds promise for the development of innovative management strategies and targeted drugs to enhance tumor therapy efficacy.

Microbial crosstalk with dermal immune system: A review on emerging analytical methods for macromolecular detection and therapeutics

According to global health metrics, clinical symptoms such as cellulitis and pyoderma associated with skin diseases are a significant burden worldwide, affecting 2.2 million disability-adjusted life years in 2020. There is a strong correlation between the commensal bacteria and the host immune system. Classical methods deployed in dermal biofilm crosstalk studies often hamper many individuals from early diagnosis and rationalized therapy. Herein, the present report aims to study the role of skin microbiota and mechanisms of microbial crosstalk with host immune system. The emerging analytical tools devised for sensor/biosensor platforms, including molecularly imprinted polymers, microarrays, aptamers, CRISPR-cas9, and optical/electrochemical approaches, are discussed as alternative methods for important biomarker analysis. Further, the types and characteristics of microorganism-derived macromolecules and the recent skin organoid toward personalized therapy are highlighted. This information will largely benefit researchers involved in the pathophysiology of skin disease, wound dressing materials, including diagnostic and healing patch designs, in addition to biological macromolecules devoted to wound repair.

Gut bacterial sphingolipid production modulates dysregulated skin lipid homeostasis

Sphingolipids are an essential lipid component of the skin barrier with alterations in skin sphingolipid composition associated with multiple skin disorders including psoriasis, atopic dermatitis, and ichthyosis. Contributions to skin sphingolipid abundance are not well characterized, thus the main method of modulating skin lipid levels is the topical application of creams rich with sphingolipids at the skin surface. Evidence that diet and gut microbiome function can alter skin biology proposes an intriguing potential for the modulation of skin lipid homeostasis through gut microbial metabolism, but potential mechanisms of action are not well understood. Sphingolipid synthesis by prominent gut microbes has been shown to affect intestinal, hepatic and immune functions with the potential for sphingolipid-producing bacteria to affect skin biology through altering skin sphingolipid levels. To address this question, we used bioorthogonal chemistry to label lipids from the sphingolipid-producing bacteria Bacteroides thetaiotaomicron and trace these lipids to the skin epidermis. Exposing mice to B. thetaiotaomicron strains mutant in the ability to produce sphingolipids resulted in significantly lower transfer of gut microbiome-derived lipids to the skin, while also altering skin biology and altering expression of skin barrier genes. Measurement of skin ceramide levels, a class of sphingolipids involved in skin barrier function, determined that skin sphingolipid levels were altered in the presence of gut sphingolipid-producing bacteria. Together this work demonstrates that gut bacterial lipids can transfer to the skin and provides a compelling avenue for modulating sphingolipid-dominant compartments of the skin using sphingolipid-producing bacteria of the gut microbiome.

Nutritional Dermatology: Optimizing Dietary Choices for Skin Health

BACKGROUND/OBJECTIVES

Youthful, smooth skin is highly desired in modern society. Individuals invest in cosmetics, plastic surgeons, and dermatologists in pursuit of perfect skin. However, many do not seek out dietary changes to improve skin health. Although research has been conducted on the role of nutrition and select nutrients and phytonutrients on skin health, there is a lack of healthy food recommendations for clear skin.

METHODS

The literature was assessed to determine which nutrients and phytonutrients play a significant role in the protection and maintenance of skin health. Key compounds were highlighted as there is evidence to suggest they have a significant role in skin health: vitamin A, vitamin C, vitamin D, vitamin E, zinc, omega-6 and omega-3 fatty acids, polyphenols/flavonoids, copper, selenium, and silicon. USDA FoodData Central and FooDB (food database), were utilized to select foods and food groups containing the key nutrients and phytonutrients.

RESULTS

A skin-healthy dietary pattern is proposed in addition to a scoring system to assess diet. A sample skin-healthy daily diet was designed, using only whole foods, that met the Daily Values for vitamins and minerals and contained key compounds for skin health.

CONCLUSIONS

There is a clear link between nutrition and skin health, or nutritional dermatology; however, more research needs to be done to find the intersection between both disciplines.

Microbial Dynamics: Assessing Skincare Regimens' Impact on the Facial Skin Microbiome and Skin Health Parameters

The human skin microbiome, a complex ecosystem of microbes, plays a pivotal role in skin health. This study aimed to investigate the impact of two skincare regimens, with preservatives (CSPs) and preservative-free (PFPs), on the skin microbiome in correlation to skin quality. double-blind randomized cosmetic studywith a split-face design was conducted on 26 female participants. Microbial diversity and abundance were analyzed using 16S rRNA amplicon sequence data and skin quality utilizing the Antera 3D skin camera. We confirmed earlier studies on the identification of major skin microbial taxa at the genus level, including Cutibacterium acnes, Corynebacterium, and Neisseriaceae as a predominant part of the facial skin microbiome. Furthermore, microbiome profile-based subgrouping was employed, which revealed that the cluster, characterized by the Neisseriaceae family as its predominant organism, exhibited significant reduction in folds count, fine lines, and redness after application of PFP compared to CSP. A Spearman correlation analysis highlighted the correlation between changes in specific bacteria and skin quality parameters such as redness, pores, and texture in the context of comparing PFP and CSP. Overall, the PFP treatment demonstrated a greater number of significant correlations between bacterial changes and skin quality compared to the CSP treatment, suggesting a distinct impact of the preservative-free skincare regimen on the skin microbiome and skin quality. Our study provides insights into different microbiome-centered approaches to improve our understanding of the skin microbiome's interplay with skin quality but also highlights the need for larger, comprehensive research to further understand the microbiome's role in dermatology.

Causal relationships between skin microbiome and pathological scars: a bidirectional mendelian randomization study

Skin bacteria infection could be a potential risk factor on wound scar formation, yet the specifics of this relationship are not fully understood. This research investigates the causal relationships between specific skin microbiome and these diseases by using bidirectional Mendelian randomization (MR). This study employed a bidirectional MR analysis using genome-wide association study (GWAS) data to analyze the associations between skin microbiome and pathological scar. Single nucleotide polymorphisms (SNPs) served as instrumental variables (IVs) in MR methods, including inverse variance weighted (IVW), and MR Egger. The IVW analysis suggested a significant relationship between specific skin microbiome and pathlogical scars. Actinomycetales_Sebaceous, Proteobacteria_Sebaceous, ASV072[Paracoccus (unc.)]_Dry, ASV008[Diaphorobacter nitroreducens]_Dry, Pseudomonadales_moist, ASV001[Propionibacterium acnes]_Moist, Moraxellaceae_moist, Flavobacteriaceae_Dry were significantly associated with keloid. Chryseobacterium_Moist, ASV016[Enhydrobacter(unc.)]_Moist, ASV021[Micrococcus(unc.)]_Moist, ASV022[Streptococcus salivarius]_Moist, Rhodobacteraceae_Dry, Staphylococcus_Moist, Micrococcaceae_Moist, ASV007[Anaerococcus(unc.)]_Dry, Betaproteobacteria_Moist and ASV001[Propionibacterium acnes]_Moist were significantly associated with hypertrophic scarring. Reverse MR analysis indicates both keloid and hypertrophic scar regulated the composition of the skin microbiome. The study revealed a possible correlation between some specific skin microbiome and pathlogical scars. Understanding these inverse relationship could help improve clinical treatment and reducing pathological scar formation.

Significance of host antimicrobial peptides in the pathogenesis and treatment of acne vulgaris

Acne vulgaris (AV) is a chronic inflammatory condition of the pilosebaceous units characterized by multiple immunologic, metabolic, hormonal, genetic, psycho-emotional dysfunctions, and skin microbiota dysbiosis. The latter is manifested by a decreased population (phylotypes, i.e., genetically distinct bacterial subgroups that play different roles in skin health and disease) diversity of the predominant skin bacterial commensal - Cutinbacterium acnes. Like in other dysbiotic disorders, an elevated expression of endogenous antimicrobial peptides (AMPs) is a hallmark of AV. AMPs, such as human β-defensins, cathelicidin LL-37, dermcidin, or RNase-7, due to their antibacterial and immunomodulatory properties, function as the first line of defense and coordinate the host-microbiota interactions. Therefore, AMPs are potential candidates for pharmaceutical prophylaxis or treating this condition. This study outlines the current knowledge regarding the importance of AMPs in AV pathomechanism in light of recent transcriptomic studies. In particular, their role in improving the tight junctions (TJs) skin barrier by activating the fundamental cellular proteins, such as PI3K, GSK-3, aPKC, and Rac1, is discussed. We hypothesized that the increased expression of AMPs and their patterns in AV act as a compensatory mechanism to protect the skin with an impaired permeability barrier. Therefore, AMPs could be key determinants in regulating AV development and progression, linking acne-associated immune responses and metabolic factors, like insulin/IGF-1 and PI3K/Akt/mTOR/FoxO1 signaling pathways or glucotoxicity. Research and development of anti-acne AMPs are also addressed.

The Hygienic Significance of Microbiota and Probiotics for Human Wellbeing

The human body can be viewed as a combination of ecological niches inhabited by trillions of bacteria, viruses, fungi, and parasites, all united by the microbiota concept. Human health largely depends on the nature of these relationships and how they are built and maintained. However, personal hygiene practices have historically been focused on the wholesale elimination of pathogens and "hygiene-challenging microorganisms" without considering the collateral damage to beneficial and commensal species. The microbiota can vary significantly in terms of the qualitative and quantitative composition both between different people and within one person during life, and the influence of various environmental factors, including age, nutrition, bad habits, genetic factors, physical activity, medication, and hygienic practices, facilitates these changes. Disturbance of the microbiota is a predisposing factor for the development of diseases and also greatly influences the course and severity of potential complications. Therefore, studying the composition of the microbiota of the different body systems and its appropriate correction is an urgent problem in the modern world. The application of personal hygiene products or probiotics must not compromise health through disruption of the healthy microbiota. Where changes in the composition or metabolic functions of the microbiome may occur, they must be carefully evaluated to ensure that essential biological functions are unaffected. As such, the purpose of this review is to consider the microbiota of each of the "ecological niches" of the human body and highlight the importance of the microbiota in maintaining a healthy body as well as the possibility of its modulation through the use of probiotics for the prevention and treatment of certain human diseases.

Facultatively Anaerobic Staphylococci Enable Anaerobic Cutibacterium Species to Grow and Form Biofilms Under Aerobic Conditions

Facultatively anaerobic Staphylococcus spp. and anaerobic Cutibacterium spp. are among the most prominent bacteria on human skin. Although skin microbes generally grow as multispecies biofilms, few studies have investigated the interaction between staphylococci and Cutibacterium spp. in dual-species biofilms. Here, we measured the mono- and dual-species biofilm formation of four staphylococcal species (S. epidermidis, S. hominis, S. capitis, and S. aureus) and two Cutibacterium spp. (C. acnes and C. avidum) cultured in vitro under both aerobic and anaerobic conditions. The biofilms were quantitated by rinsing them to remove planktonic cells, detaching the biofilm bacteria via sonication, and enumerating the cells by dilution plating. When cultured alone, staphylococci formed biofilms under both aerobic and anaerobic conditions, whereas Cutibacterium spp. formed biofilms only under anaerobic conditions. In co-culture, staphylococcal biofilm formation was unaffected by the presence of Cutibacterium spp., regardless of oxygen availability. However, Cutibacterium spp. biofilm formation was significantly enhanced in the presence of staphylococci, enabling robust growth under both anaerobic and aerobic conditions. Fluorescence confocal microscopy of the aerobic dual-species biofilms suggested that staphylococci create anaerobic niches at the base of the biofilm where C. acnes can grow. These findings demonstrate that staphylococci facilitate the colonization of Cutibacterium spp. in oxygen-rich environments, potentially explaining their presence in high numbers on the oxygen-exposed stratum corneum.

Unveiling the hidden causal links: skin flora and cutaneous melanoma

Objective

The presence of skin flora (SF) has been identified as a significant factor in the onset and progression of cutaneous melanoma (CM). However, the vast diversity and abundance of SF present challenges to fully understanding the causal relationship between SF and CM.

Methods

A Two Sample Mendelian Randomization (TSMR) analysis was conducted to investigating the causal relationship between SF and CM. The Inverse-Variance Weighted (IVW) method was utilized as the primary approach to assess the causal relationship under investigation. Furthermore, an independent external cohort was employed to validate the initial findings, followed by a meta-analysis of the consolidated results. To address potential confounding factors related to the influence of SF on CM, a Multivariate Mendelian Randomization (MVMR) analysis was also conducted. Finally, a Reverse Mendelian Randomization (RMR) was conducted to further validate the causal association.

Results

TSMR results showed that 9 SF have a causal relationship with CM in the training cohort. Although these 9 SF weren't confirmed in the testing cohort, 4 SF remained significant in the meta-analysis after integrating results from both cohorts. MVMR analysis indicated that 3 SF were still significantly associated with CM after accounting for the interactions between different SF in the training cohort. No reverse causal relationship was identified in RMR analysis.

Conclusion

A total of 9 SF were identified as having a potential causal relationship with CM; however, a large randomized controlled trial is needed to verify these results.

Antimicrobial Resistance Profiles and mupA Gene Characterization of Staphylococcus epidermidis Recovered from Facial Skin of Healthy Females in Shanghai, China

Purpose

To explore antimicrobial resistance profiles and mupA gene characterization of Staphylococcus epidermidis recovered from facial skin of healthy females in Shanghai, China.

Patients and Methods

In this study, we collected facial skin samples from 107 healthy females in Shanghai, China, and S. epidermidis isolation was performed. The minimal inhibitory concentrations of 10 antibiotics were determined for the S. epidermidis isolates using the agar dilution method. High-level mupirocin-resistant isolates were subjected to whole-genome sequencing and bioinformatics analysis. A total of 94 un-duplicated S. epidermidis isolates were obtained from 107 facial skin samples.

Results

Antimicrobial susceptibility tests revealed that 23.4% of the 94 S. epidermidis isolates were resistant to oxacillin and positive for the mecA gene, which could be cauterized as methicillin-resistant S. epidermidis (MRSE). Resistance rates for erythromycin, clindamycin, tetracycline, ciprofloxacin, and gentamicin were 8.5%, 11.7%, 10.6%, 12.8%, and 1.1%, respectively. For mupirocin, the rates of low- and high-level resistance were 3.2% (3/94) and 11.7% (11/94), respectively. Resistance to vancomycin or linezolid was not observed. High-level mupirocin resistance in facial skin isolates is mediated by mupA. WGS and SNP-based phylogenetic analyses revealed diverse phylogenies among the 11 mupA-positive S. epidermidis isolates. Additionally, various resistance and virulence genes were identified in mupA-positive isolates. A new hybrid plasmid carrying mupA genes was found in two S. epidermidis isolates.

Conclusion

We observed a considerable level of antimicrobial resistance to several antibiotics and the prevalence of abundant and diverse resistance and virulence genes in the facial skin-origin S. epidermidis isolates. This may pose a potential risk for both public health and S. epidermidis infection.

Hyaluronan Scaffold Decorated with Bifunctional Peptide Promotes Wound Healing via Antibacterial and Anti-Inflammatory

The invasion of bacteria and inflammation impeded infected wounds heal. Here, a hyaluronan-based scaffold (HAG-g-C) was designed by cross-linking with gallic acid-modified gelatin to provide a protein microenvironment and decorated with cathelicidin-BF (CBF), a natural antimicrobial peptide, to remove bacterial infections and reverse the inflammatory environment. In vitro, HAG-g-C presented an antibacterial effect on Staphylococcus aureus and Escherichia coli. Meanwhile, it could drive the phenotypic switch of macrophage from M1 to M2 to accelerate tissue remodeling. In a mouse model of S. aureus-infected total skin defects, HAG-g-C inhibited the process of infection at the beginning of the wound and then regulated the M1 macrophage transformed to M2 phenotype on day 12. In addition, HAG-g-C induced collagen deposition, and reduced the expression of TNF-α, thereby significantly accelerating the reconstruction of infected wounds.

The Causal Effect Between Human Microbiota and Scabies: A Study from the Genetic Perspective

Background

Previous studies have indicated that human flora may affect the development of scabies, however, no studies have proven a causal relationship between human flora and scabies, which would be detrimental to future in-depth studies on human flora and scabies.

Methods

Mendelian randomization (MR) was used to analyze the causal effect between human microbiota and scabies, with data on intestinal flora and skin flora from two large published studies and data on scabies from the FinnGen database. Five MR analysis methods were used to increase the reliability of the results, and sensitivity analyses were conducted to increase the robustness of the results.

Results

Our results suggest that 13 intestinal flora as well as 7 skin flora can have a causal effect on scabies.

Conclusion

Overall, our results demonstrate a causal relationship between intestinal and skin flora and scabies and are consistent with previous observational findings. This will contribute to the future development of probiotic agents for the prevention or treatment of scabies.

Sustainable lignin-based composite hydrogels for controlled drug release and self-healing in antimicrobial wound dressing

Bacterial infections pose a significant threat to global public health, demanding innovative solutions in biomedical field. Lignin is a naturally abundant polyphenol-rich polymer, offer promising potential to fabricate advance biomaterials for biomedical applications. Hence, a composite hydrogel with antimicrobial and antioxidant activities based on the development of dynamic covalent bonds among sodium alginate, lignin and epigallocatechin-3-gallate (EGCG) was designed. Lignin provides structural integrity to hydrogel backbone as well as released synergistically with the drug. This synergistic effect of the pH-responsive controlled release of both EGCG and lignin improved the releasing ability and bioactivity of the hydrogels. In in vitro antimicrobial experiments, the addition of 3.08 wt% lignin significantly enhanced bactericidal efficacy against Escherichia coli and Staphylococcus aureus, raising the killing rate from 20 % to over 96 %. The dynamic borate bond allows hydrogel network to repair itself when it is disrupted. Its self-healing ability, pH-responsive drug delivery, biocompatibility and strong antimicrobial and antioxidant effects make it a promising candidate for chronic wound management. This lignin-based hydrogel marks a significant innovation in sustainable, multifunctional biomedical materials.

Involvement of Urease-Producing Bacteria on Genital Skin in Community-Dwelling Women with Incontinence-Associated Dermatitis: A Cross-Sectional Study

Purpose

Elevated skin pH facilitates the number of pathogenic bacteria increase, leading to the skin barrier dysfunction. This phenomenon is typically observed in individuals with Incontinence-associated dermatitis (IAD), which imposes a substantial physical and psychological burden on the afflicted individuals. We evaluated the association between the development of IAD in community-dwelling women with urinary incontinence and cutaneous urease-producing bacteria, as these bacteria may be involved in elevating skin pH by chemical reaction with urea in urine.

Patients and Methods

This was a cross-sectional study of 114 community-dwelling women with urinary incontinence who had registered for a survey campaign of a company. Swabs collected from genital skin were cultured in urea agar medium. The presence of urease-producing bacteria was determined by visually observing the change in the color of the culture medium caused by alkalization. The medium pH and total bacteria count were measured. Bacterial species were isolated and identified using a selective agar medium and simple identification kits. The participants were asked the presence of IAD by a self-administered questionnaire, and outcomes were compared between the IAD and no-IAD groups. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline.

Results

IAD was present in 31.6% (36/114) of participants. The detection rate of urease-producing bacteria and the medium pH was significantly higher in the IAD group than in the no-IAD group; however, the total number of bacteria was not significantly different. There were no significant between-group differences regarding the bacterial species identified.

Conclusion

The presence of urease-producing bacteria was associated with the development of IAD in community-dwelling women with urinary incontinence. Alkalization of the genital skin surface because of the contact between urine and urease-producing bacteria may compromise skin homeostasis. The bacterial species specifically involved in the development of IAD could not be determined.

The bacterial burden of worn face masks-observational research and literature review

Introduction

Facemasks were widely mandated during the recent SARS-CoV-2 pandemic. Especially the use by the general population is associated with a higher risk of improper handling of the mask and contamination and potential adverse microbiological consequences.

Methods

We investigated and quantified bacterial accumulation in facemasks used by the general population, using 16S rRNA (Sanger Sequencing), culture and biochemical analysis along with Rose Bengal staining. Additionally, a systematic overview of the literature on face mask contamination was undertaken.

Results

We found an average bacterial load of 4.24 × 104 CFU recovered/mask, with a maximum load of 2.85 × 105 CFU. This maximum is 310 times higher than the limit value for contamination of ventilation system outlet surfaces specified by the German standard VDI 6022. Biochemical and molecular identification predominantly found Staphylococcus species (80%), including Staphylococcus aureus, along with endospore-forming Bacillus spp. Literature reports also indicate contamination of masks by bacterial and fungal opportunists of the genera Acinetobacter, Aspergillus, Alternaria, Bacillus, Cadosporium, Candida, Escherichia, Enterobacter, Enterococcus, Klebsiella (including K. pneumoniae), Micrococcus, Microsporum, Mucor, Pseudomonas, Staphylococcus and Streptococcus. Bacterial counts increase linearly with wearing duration.

Discussion

Prolonged use may affect the skin and respiratory microbiomes, promoting consequential eye, skin, oral and airway conditions. These aspects underscore the urgent need for further research and a risk-benefit analysis in respect of mask use, particularly given their unproven efficacy in disrupting the transmission of respiratory viruses and their adverse social consequences.

Microbial interactions shaping host attractiveness: insights into dynamic behavioral relationships

Insects discern the presence of hosts (host plants) by integrating chemosensory, gustatory, and visual cues, with olfaction playing a pivotal role in this process. Among these factors, volatile signals produced by host-associated microbial communities significantly affect insect attraction. Microorganisms are widely and abundantly found on the surfaces of humans, plants, and insects. Notably, these microorganisms can metabolize compounds from the host surface and regulate the production of characteristic volatiles, which may guide the use of host microorganisms to modulate insect behavior. Essentially, the attraction of hosts to insects is intricately linked to the presence of their symbiotic microorganisms. This review underscores the critical role of microorganisms in shaping the dynamics of attractiveness between insects and their hosts.

Deciphering microbiome and fungi-bacteria interactions in chronic wound infections using metagenomic sequencing

PURPOSE

Chronic wounds caused by infections impose a considerable global healthcare burden. The microbial features of these infections and possible correlations between bacteria and fungi may influence wound healing. However, metagenomic next-generation sequencing (mNGS) analyses of these features remain sparse. Therefore, we performed mNGS on chronic wound infection samples to investigate features and correlations between the bacteriome and mycobiome in 66 patients (28: chronic wounds; 38: non-chronic wounds).

METHODS

Microbial community characteristics in patients with wound infections, microbiome-systemic inflammation associations, and bacteria-fungi correlations were analyzed.

RESULTS

Infections constituted the primary cause of wounds in this study. Nontuberculous mycobacteria (23%) and Mycobacterium tuberculosis (13%) were the most common pathogens associated with chronic wounds, whereas Staphylococcus aureus (15%) was the most prevalent in non-chronic wound infections. Patients with chronic wound infections had a higher abundance of Pseudomonas aeruginosa than those without chronic wounds. Microbes with a high relative abundance in chronic wound infections were less significantly associated with plasma inflammatory factors than those in non-chronic wound infections. Additionally, a positive correlation between Candida glabrata and P. aeruginosa and an association between Malassezia restricta and anaerobic species were detected in patients with chronic wound infections.

CONCLUSION

Our results further support the hypothesis that P. aeruginosa is a microbial biomarker of chronic wound infection regardless of the causative pathogens. Moreover, we propose a positive correlation between C. glabrata and P. aeruginosa in chronic wound infections, which advances the current understanding of fungi-bacteria correlations in patients with chronic wound infections.

The influence of lifestyle and environmental factors on host resilience through a homeostatic skin microbiota: An EAACI Task Force Report

Human skin is colonized with skin microbiota that includes commensal bacteria, fungi, arthropods, archaea and viruses. The composition of the microbiota varies at different anatomical locations according to changes in body temperature, pH, humidity/hydration or sebum content. A homeostatic skin microbiota is crucial to maintain epithelial barrier functions, to protect from invading pathogens and to interact with the immune system. Therefore, maintaining homeostasis holds promise to be an achievable goal for microbiome-directed treatment strategies as well as a prophylactic strategy to prevent the development of skin diseases, as dysbiosis or disruption of homeostatic skin microbiota is associated with skin inflammation. A healthy skin microbiome is likely modulated by genetic as well as environmental and lifestyle factors. In this review, we aim to provide a complete overview of the lifestyle and environmental factors that can contribute to maintaining the skin microbiome healthy. Awareness of these factors could be the basis for a prophylactic strategy to prevent the development of skin diseases or to be used as a therapeutic approach.

Advances in Microbiome-Based Therapeutics for Dermatological Disorders: Current Insights and Future Directions

The human skin hosts an estimated 1000 bacterial species that are essential for maintaining skin health. Extensive clinical and preclinical studies have established the significant role of the skin microbiome in dermatological disorders such as atopic dermatitis, psoriasis, diabetic foot ulcers, hidradenitis suppurativa and skin cancers. In these conditions, the skin microbiome is not only altered but, in some cases, implicated in disease pathophysiology. Microbiome-based therapies (MBTs) represent an emerging category of live biotherapeutic products with tremendous potential as a novel intervention platform for skin diseases. Beyond using established wild-type strains native to the skin, these therapies can be enhanced to express targeted therapeutic molecules, offering more tailored treatment approaches. This review explores the role of the skin microbiome in various common skin disorders, with a particular focus on the development and therapeutic potential of MBTs for treating these conditions.