The Skin Microbiome: Current Landscape and Future Opportunities

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.

Beyond antibiotics: mesenchymal stem cells and bacteriophages-new approaches to combat bacterial resistance in wound infections

Wound management is a major global health problem. With the rising incidence of diabetic wounds, accidents, and other injuries, the demand for prompt wound treatment has become increasingly critical. Millions of people suffer from serious, large wounds resulting from major accidents, surgeries, and wars. These wounds require considerable time to heal and are susceptible to infection. Furthermore, chronic wounds, particularly in elderly and diabetic patients, often require frequent medical interventions to prevent complications. Consequently, wound management imposes a significant economic burden worldwide. The complications arising from wound infections can vary from localized issues to systemic effects. The most severe local complication of wound infection is the non-healing, which results from the disruption of the wound-healing process. This often leads to significant pain, discomfort, and psychological trauma for the patient. Systemic complications may include cellulitis, osteomyelitis, and septicemia. Mesenchymal stem cells are characterized by their high capacity for division, making them suitable candidates for the treatment of tissue damage. Additionally, they produce antimicrobial peptides and various cytokines, which enhance their antimicrobial activity. Evidence shows that phages are effective in treating wound-related infections, and phage therapy has proven to be highly effective for patients when administered correctly. The purpose of this article is to explore the use of bacteriophages and mesenchymal stem cells in wound healing and infection management.

Dermatological Health in the Light of Skin Microbiome Evolution

BACKGROUND

The complex ecosystem of the skin microbiome is essential for skin health by acting as a primary defense against infections, regulating immune responses, and maintaining barrier integrity. This literature review aims to consolidate existing information on the skin microbiome, focusing on its composition, functionality, importance, and its impact on skin aging.

METHODS

An exhaustive exploration of scholarly literature was performed utilizing electronic databases including PubMed, Google Scholar, and ResearchGate, focusing on studies published between 2011 and 2024. Keywords included "skin microbiome," "skin microbiota," and "aging skin." Studies involving human subjects that focused on the skin microbiome's relationship with skin health were included. Out of 100 initially identified studies, 70 met the inclusion criteria and were reviewed.

RESULTS

Studies showed that aging is associated with a reduction in the variety of microorganisms of the skin microbiome, leading to an increased susceptibility to skin conditions. Consequently, this underlines the interest in bacteriotherapy, mainly topical probiotics, to reinforce the skin microbiome in older adults, suggesting improvements in skin health and a reduction in age-related skin conditions. Further exploration is needed into the microbiome's role in skin health and the development of innovative, microbe-based skincare products. Biotherapeutic approaches, including the use of phages, endolysins, probiotics, prebiotics, postbiotics, and microbiome transplantation, can restore balance and enhance skin health. This article also addresses regulatory standards in the EU and the USA that ensure the safety and effectiveness of microbial skincare products.

CONCLUSION

This review underscores the need to advance research on the skin microbiome's role in cosmetic enhancements and tailored skincare solutions, highlighting a great interest in leveraging microbial communities for dermatological benefits.

Exploring mechanisms of skin aging: insights for clinical treatment

The skin is the largest organ in the human body and is made up of various cells and structures. Over time, the skin will age, which is not only influenced by internal factors, but also by external environmental factors, especially ultraviolet radiation. Aging causes immune system weakening in the elderly, which makes them more susceptible to dermatosis, such as type 2 inflammatory mediated pruritus. The immune response in this condition is marked by senescent cells consistently releasing low amounts of pro-inflammatory cytokines through a senescence-associated secretory phenotype (SASP). This continuous inflammation may accelerate immune system aging and establish a connection between immune aging and type 2 inflammatory skin diseases. In addition, two chronic pigmentation disorders, vitiligo and chloasma, are also associated with skin aging. Aged cells escape the immune system and accumulate in tissues, forming a microenvironment that promotes cancer. At the same time, "photoaging" caused by excessive exposure to ultraviolet radiation is also an important cause of skin cancer. This manuscript describes the possible links between skin aging and type 2 inflammation, chronic pigmentation disorders, and skin cancer and suggests some treatment options.

Can salivary and skin microbiome become a biodetector for aging-associated diseases? Current insights and future perspectives

Growth and aging are fundamental elements of human development. Aging is defined by a decrease in physiological activities and higher illness vulnerability. Affected by lifestyle, environmental, and hereditary elements, aging results in disorders including cardiovascular, musculoskeletal, and neurological diseases, which accounted for 16.1 million worldwide deaths in 2019. Stress-induced cellular senescence, caused by DNA damage, can reduce tissue regeneration and repair, promoting aging. The root cause of many age-related disorders is inflammation, encouraged by the senescence-associated secretory phenotype (SASP). Aging's metabolic changes and declining immune systems raise illness risk via promoting microbiome diversity. Stable, individual-specific skin and oral microbiomes are essential for both health and disease since dysbiosis is linked with periodontitis and eczema. Present from birth to death, the human microbiome, under the influence of diet and lifestyle, interacts symbiotically with the body. Poor dental health has been linked to Alzheimer's and Parkinson's diseases since oral microorganisms and systemic diseases have important interactions. Emphasizing the importance of microbiome health across the lifetime, this study reviews the understanding of the microbiome's role in aging-related diseases that can direct novel diagnosis and treatment approaches.

Modulations of the skin microbiome in skin disorders: A narrative review from a wound care perspective

The cutaneous microbiome represents a highly dynamic community of bacteria, fungi and viruses. Scientific evidence, particularly from the last two decades, has revealed that these organisms are far from being inconsequential microscopic hitchhikers on the human body, nor are they all opportunistic pathogens waiting for the chance to penetrate the skin barrier and cause infection. In this review, we will describe how dermatological diseases have been found to be associated with disruptions and imbalances in the skin microbiome and how this new evidence had shaped the diagnosis and clinical practice relating to these disorders. We will identify the microbial agents which have been found to directly exacerbate skin diseases, as well as those which can ameliorate many of the symptoms associated with dermatological disorders. Furthermore, we will discuss the studies which suggest that bacteriotherapy, either by topical use of probiotics or by bacteria-derived compounds, can rectify skin microbial imbalances, thereby offering a promising alternative to antibiotic treatment and reducing the risks of antibiotic resistance.

Development of carboxymethyl cellulose/gelatin hydrogel loaded with Omega-3 for skin regeneration

Hydrogels have several characteristics, including biocompatibility, physical similarity with the skin's extracellular matrix, and regeneration capacity. Cell migration and proliferation are facilitated by natural polymers such as gelatin (Gel) and carboxymethyl cellulose (CMC). Gelatin dressing acts as a structural framework for cell migration into the wound area, stimulating cell division and promoting granulation tissue formation. Omega-3 fatty acids from fish oil may prevent wound infection and improve the healing of wounds in the early stages. We studied the preparation of wound dressing containing Omega-3 and its ability to heal wounds. In this study, CMC-Gel hydrogels containing different concentrations of Omega-3 were investigated in full-thickness wounds. After the fabrication of the hydrogels by using surfactant (tween 20) and microemulsion method (oil in water), various tests such as SEM, Water uptake evaluation, weight loss, cell viability, blood compatibility, and in vivo study in rat cutaneous modeling during 14 days were performed to evaluate the properties of the fabricated hydrogels. The analysis of the hydrogels revealed that they possess porous structures with interconnected pores, with an average size of 83.23 ± 6.43 μm. The hydrogels exhibited a swelling capacity of up to 60% of their initial weight within 24 h, as indicated by the weight loss and swelling measurements. Cell viability study with the MTT technique showed that no cytotoxicity was observed at the recommended dosage, however, increasing the amount of omega-3 caused hemolysis, cell death, and inhibition of coagulation activity. An in vivo study in adult male rats with a full-thickness model showed greater than 91% improvement of the primary wound region after 2 weeks of treatment. Histological analysis demonstrated Omega-3 in hydrogels, which is a promising approach for topical skin treatment to prevent scar, and has shown efficacy as wound dressing by improving the repair process at the defect site.

Microbial Dysbiosis in the Skin Microbiome and Its Psychological Consequences

The homeostasis of the skin microbiome can be disrupted by both extrinsic and intrinsic factors, leading to a state of dysbiosis. This imbalance has been observed at the onset of persistent skin diseases that are closely linked to mental health conditions like anxiety and depression. This narrative review explores recent findings on the relationship between the skin microbiome and the pathophysiology of specific skin disorders, including acne vulgaris, atopic dermatitis, psoriasis, and wound infections. Additionally, it examines the psychological impact of these skin disorders, emphasizing their effect on patients' quality of life and their association with significant psychological consequences, such as anxiety, depression, stress, and suicidal ideation in the most severe cases.

Valorisation of tomato pomace in anti-pollution and microbiome-balance face cream

Tomato pomace, the main by-product of tomato processing, is also an underestimated source of many active substances. This study aimed to determine the possibility of using oil obtained from tomato pomace in a face cream formulation. The bacterial community structure, face skin biophysical parameters and protection against air pollution were examined after daily application of the cosmetic by volunteers. In the tomato pomace oil, the profile of fatty acids was determined by GC‒MS, and the profile of volatile compounds was determined using the HS-SPME technique. The dominant bioactive component in the oil was linoleic acid (63.6%), and among the volatile compounds, it was carvotanacetone (25.8%). The application of the cream with tomato pomace oil resulted in an increase in the dominant genera Staphylococcus, Anaerococcus and Cutibacterium in the epibiome, particularly beneficial Staphylococcus epidermidis, while limiting the growth of the potentially opportunistic pathogens Kocuria spp., Micrococcus spp., Veillonella spp., and Rothia spp. This study showed the usefulness of tomato pomace oil as a natural ingredient in skin care cosmetics, reducing skin inflammation, sensitivity and melanin level, with potential protective effects against air pollution and microbiome-balance properties. Tomato pomace, which is commonly considered waste after tomato processing, can be used in the development of new cosmetics and may additionally contribute to reducing environmental nuisance.

Comparison of the Skin Microbiota in the Periocular Region between Patients with Inflammatory Skin Diseases and Healthy Participants: A Preliminary Study

(1) Background: Periocular or periorbital dermatitis is a common term for all inflammatory skin diseases affecting the area of skin around the eyes. The clear etiopathogenesis of periocular dermatitis is still not fully understood. Advances in molecular techniques for studying microorganisms living in and on our bodies have highlighted the microbiome as a possible contributor to disease, as well as a promising diagnostic marker and target for innovative treatments. The aim of this study was to compare the composition and diversity of the skin microbiota in the periocular region between healthy individuals and individuals affected by the specific entity of periocular dermatitis. (2) Methods: A total of 35 patients with periocular dermatitis and 39 healthy controls were enrolled in the study. After a skin swab from the periocular region was taken from all participants, DNA extraction and 16S rRNA gene amplicon sequencing using Illumina NovaSeq technology were performed. (3) Results: Staphylococcus and Corynebacterium were the most abundant bacterial genera in the microbiota of healthy skin. Analysis of alpha diversity revealed a statistically significant change (p < 0.05) in biodiversity based on the Faith's PD index between patients and healthy individuals. We did not observe changes in beta diversity. The linear discriminant analysis effect size (LEfSe) revealed that Rothia, Corynebacterium, Bartonella, and Paracoccus were enriched in patients, and Anaerococcus, Bacteroides, Porphyromonas, and Enhydrobacter were enriched in healthy controls. (4) Conclusions: According to the results obtained, we assume that the observed changes in the bacterial microbiota on the skin, particularly Gram-positive anaerobic cocci and skin commensals of the genus Corynebacterium, could be one of the factors in the pathogenesis of the investigated inflammatory diseases. The identified differences in the microbiota between healthy individuals and patients with periocular dermatitis should be further investigated.

The microbiome of Total Suspended Particles (TSP) and its influence on the respiratory microbiome of healthy office workers

Air particulate matter (PM) is widely recognized for its potential to negatively affect human health, including changes in the upper respiratory microbiome. However, research on PM-associated microbiota remains limited and mostly focused on PM (e.g., PM2.5 and PM10). This study aims to characterize for the first time the microbiome of Total Suspended Particles (TSP) and investigate the correlations of indoor TSP with the human upper respiratory microbiome. Biological and environmental samples were collected over three collection periods lasting three weeks each, between May and July 2022 at the University of Milan and the University of Insubria Como. TSP were sampled using a filter-based technique, while respiratory samples from both anterior nares (AN) and the nasopharynx (NP) were collected using swabs. Microbiome analysis of both human (N = 145) and TSP (N = 51) samples was conducted on metagenomic sequencing data. A comparison of indoor and outdoor TSP microbiomes revealed differences in microbial diversity and taxonomic composition. The indoor samples had higher relative abundance of environmental bacteria often associated with opportunistic infections like Paracoccus sp., as well as respiratory bacteria such as Staphylococcus aureus and Klebsiella pneumoniae. Additionally, both indoor and outdoor TSP samples contained broad spectrum antibiotic resistance genes. Indoor TSP exposure was negatively associated with commensal bacteria and positively associated with Staphylococcus aureus relative abundance. Finally, a correlation between the relative abundance of respiratory bacteria identified in the indoor TSP and the upper respiratory microbiome was found, suggesting a potential interaction between TSP and the upper airways.

Microbiological insights and dermatological applications of live biotherapeutic products

As our understanding of dermatological conditions advances, it becomes increasingly evident that traditional pharmaceutical interventions are not universally effective. The intricate balance of the skin microbiota plays a pivotal role in the development of various skin conditions, prompting a growing interest in probiotics, or live biotherapeutic products (LBPs), as potential remedies. Specifically, the topical application of LBPs to modulate bacterial populations on the skin has emerged as a promising approach to alleviate symptoms associated with common skin conditions. This review considers LBPs and their application in addressing a wide spectrum of dermatological conditions with particular emphasis on three key areas: acne, atopic dermatitis, and wound healing. Within this context, the critical role of strain selection is presented as a pivotal factor in effectively managing these dermatological concerns. Additionally, the review considers formulation challenges associated with probiotic viability and proposes a personalised approach to facilitate compatibility with the skin's unique microenvironment. This analysis offers valuable insights into the potential of LBPs in dermatological applications, underlining their promise in reshaping the landscape of dermatological treatments while acknowledging the hurdles that must be overcome to unlock their full potential.

Selective Depletion of Staphylococcus aureus Restores the Skin Microbiome and Accelerates Tissue Repair after Injury

Our skin is home to a diverse community of commensal microorganisms integral to cutaneous function. However, microbial dysbiosis and barrier perturbation increase the risk of local and systemic infection. Staphylococcus aureus is a particularly problematic bacterial pathogen, with high levels of antimicrobial resistance and direct association with poor healing outcome. Innovative approaches are needed to selectively kill skin pathogens, such as S aureus, without harming the resident microbiota. In this study, we provide important data on the selectivity and efficacy of an S aureus-targeted endolysin (XZ.700) within the complex living skin/wound microbiome. Initial cross-species comparison using Nanopore long-read sequencing identified the translational potential of porcine rather than murine skin for human-relevant microbiome studies. We therefore performed an interventional study in pigs to assess the impact of endolysin administration on the microbiome. XZ.700 selectively inhibited endogenous porcine S aureus in vivo, restoring microbial diversity and promoting multiple aspects of wound repair. Subsequent mechanistic studies confirmed the importance of this microbiome modulation for effective healing in human skin. Taken together, these findings strongly support further development of S aureus-targeted endolysins for future clinical management of skin and wound infections.

Induction of acute silkworm hemolymph melanization by Staphylococcus aureus treated with peptidoglycan-degrading enzymes

Staphylococcus aureus, a Gram-positive bacterium, causes inflammatory skin diseases, such as atopic dermatitis, and serious systemic diseases, such as sepsis. In the skin and nasal environment, peptidoglycan (PGN)-degrading enzymes, including lysozyme and lysostaphin, affects S. aureus PGN. However, the effects of PGN-degrading enzymes on the acute innate immune-inducing activity of S. aureus have not yet been investigated. In this study, we demonstrated that PGN-degrading enzymes induce acute silkworm hemolymph melanization by S. aureus. Insoluble fractions of S. aureus treated with lysozyme, lysostaphin, or both enzymes, were prepared. Melanization of the silkworm hemolymph caused by the injection of these insoluble fractions was higher than that of S. aureus without enzyme treatment. These results suggest that structural changes in S. aureus PGN caused by PGN-degrading enzymes affect the acute innate immune response in silkworms.

Exploring the skin microbiome in atopic dermatitis pathogenesis and disease modification

Inflammatory skin diseases such as atopic eczema (atopic dermatitis [AD]) affect children and adults globally. In AD, the skin barrier is impaired on multiple levels. Underlying factors include genetic, chemical, immunologic, and microbial components. Increased skin pH in AD is part of the altered microbial microenvironment that promotes overgrowth of the skin microbiome with Staphylococcus aureus. The secretion of virulence factors, such as toxins and proteases, by S aureus further aggravates the skin barrier deficiency and additionally disrupts the balance of an already skewed immune response. Skin commensal bacteria, however, can inhibit the growth and pathogenicity of S aureus through quorum sensing. Therefore, restoring a healthy skin microbiome could contribute to remission induction in AD. This review discusses direct and indirect approaches to targeting the skin microbiome through modulation of the skin pH; UV treatment; and use of prebiotics, probiotics, and postbiotics. Furthermore, exploratory techniques such as skin microbiome transplantation, ozone therapy, and phage therapy are discussed. Finally, we summarize the latest findings on disease and microbiome modification through targeted immunomodulatory systemic treatments and biologics. We believe that targeting the skin microbiome should be considered a crucial component of successful AD treatment in the future.

Acid-treated Staphylococcus aureus induces acute silkworm hemolymph melanization

The skin microbiome maintains healthy human skin, and disruption of the microbiome balance leads to inflammatory skin diseases such as folliculitis and atopic dermatitis. Staphylococcus aureus and Cutibacterium acnes are pathogenic bacteria that simultaneously inhabit the skin and cause inflammatory diseases of the skin through the activation of innate immune responses. Silkworms are useful invertebrate animal models for evaluating innate immune responses. In silkworms, phenoloxidase generates melanin as an indicator of innate immune activation upon the recognition of bacterial or fungal components. We hypothesized that S. aureus and C. acnes interact to increase the innate immunity-activating properties of S. aureus. In the present study, we showed that acidification is involved in the activation of silkworm hemolymph melanization by S. aureus. Autoclaved-killed S. aureus (S. aureus [AC]) alone does not greatly activate silkworm hemolymph melanization. On the other hand, applying S. aureus [AC] treated with C. acnes culture supernatant increased the silkworm hemolymph melanization. Adding C. acnes culture supernatant to the medium decreased the pH. S. aureus [AC] treated with propionic acid, acetic acid, or lactic acid induced higher silkworm hemolymph melanization activity than untreated S. aureus [AC]. S. aureus [AC] treated with hydrochloric acid also induced silkworm hemolymph melanization. The silkworm hemolymph melanization activity of S. aureus [AC] treated with hydrochloric acid was inhibited by protease treatment of S. aureus [AC]. These results suggest that acid treatment of S. aureus induces innate immune activation in silkworms and that S. aureus proteins are involved in the induction of innate immunity in silkworms.

Approach to the diagnosis and management of dysbiosis

All microorganisms like bacteria, viruses and fungi that reside within a host environment are considered a microbiome. The number of bacteria almost equal that of human cells, however, the genome of these bacteria may be almost 100 times larger than the human genome. Every aspect of the physiology and health can be influenced by the microbiome living in various parts of our body. Any imbalance in the microbiome composition or function is seen as dysbiosis. Different types of dysbiosis are seen and the corresponding symptoms depend on the site of microbial imbalance. The contribution of the intestinal and extra-intestinal microbiota to influence systemic activities is through interplay between different axes. Whole body dysbiosis is a complex process involving gut microbiome and non-gut related microbiome. It is still at the stage of infancy and has not yet been fully understood. Dysbiosis can be influenced by genetic factors, lifestyle habits, diet including ultra-processed foods and food additives, as well as medications. Dysbiosis has been associated with many systemic diseases and cannot be diagnosed through standard blood tests or investigations. Microbiota derived metabolites can be analyzed and can be useful in the management of dysbiosis. Whole body dysbiosis can be addressed by altering lifestyle factors, proper diet and microbial modulation. The effect of these interventions in humans depends on the beneficial microbiome alteration mostly based on animal studies with evolving evidence from human studies. There is tremendous potential for the human microbiome in the diagnosis, treatment, and prognosis of diseases, as well as, for the monitoring of health and disease in humans. Whole body system-based approach to the diagnosis of dysbiosis is better than a pure taxonomic approach. Whole body dysbiosis could be a new therapeutic target in the management of various health conditions.

A guide to germ-free and gnotobiotic mouse technology to study health and disease

The intestinal microbiota has major influence on human physiology and modulates health and disease. Complex host-microbe interactions regulate various homeostatic processes, including metabolism and immune function, while disturbances in microbiota composition (dysbiosis) are associated with a plethora of human diseases and are believed to modulate disease initiation, progression and therapy response. The vast complexity of the human microbiota and its metabolic output represents a great challenge in unraveling the molecular basis of host-microbe interactions in specific physiological contexts. To increase our understanding of these interactions, functional microbiota research using animal models in a reductionistic setting are essential. In the dynamic landscape of gut microbiota research, the use of germ-free and gnotobiotic mouse technology, in which causal disease-driving mechanisms can be dissected, represents a pivotal investigative tool for functional microbiota research in health and disease, in which causal disease-driving mechanisms can be dissected. A better understanding of the health-modulating functions of the microbiota opens perspectives for improved therapies in many diseases. In this review, we discuss practical considerations for the design and execution of germ-free and gnotobiotic experiments, including considerations around germ-free rederivation and housing conditions, route and timing of microbial administration, and dosing protocols. This comprehensive overview aims to provide researchers with valuable insights for improved experimental design in the field of functional microbiota research.

Fungal coexistence in the skin mycobiome: a study involving Malassezia, Candida, and Rhodotorula

Evidence of fungal coexistence in humans points towards fungal adaptation to the host environment, like the skin. The human commensal Malassezia has evolved, especially residing in sebum-rich areas of the mammalian body where it can get the necessary nutrition for its survival. This fungus is primarily responsible for skin diseases like Pityriasis versicolor (PV), characterized by hypo or hyperpigmented skin discoloration and erythematous macules. In this manuscript, we report a 19-year-old healthy female who presented with a one-year history of reddish, hypopigmented, asymptomatic lesions over the chest and a raised erythematous lesion over the face. Upon clinical observation, the patient displayed multiple erythematous macules and erythematous papules over the bilateral malar area of the face, along with multiple hypopigmented scaly macules present on the chest and back. Based on the above clinical findings, a diagnosis of PV and Acne vulgaris (AV) was made. Interestingly, the patient was immunocompetent and didn't have any comorbidities. Upon isolation of skin scrapings and post-culturing, we found the existence of three fungal genera in the same region of the patient's body. We further went on to confirm the identity of the particular species and found it to represent Malassezia, Rhodotorula, and Candida. We report how Malassezia, the predominant microbial resident skin fungus, coexists with other fungal members of the skin mycobiome. This study on an applied aspect of microbiology also shows how important it is to identify the fungal organism associated with skin infections so that appropriate therapeutics can be advised to avoid cases of relapse.

Understanding the ideal wound healing mechanistic behavior using in silico modelling perspectives: A review

Complexity of the entire body precludes an accurate assessment of the specific contributions of tissues or cells during the healing process, which might be expensive and time consuming. Because of this, controlling the wound's size, depth, and dimensions may be challenging, and there is not yet an efficient and reliable chronic wound model representation. Furthermore, given the inherent challenges associated with conducting non-invasive in vivo investigations, it becomes peremptory to explore alternative methodologies for studying wound healing. In this context, biologically-realistic mathematical and computational models emerge as a valuable framework that can effectively address this need. Therefore, it might improve our approach to understanding the process at its core. This article will examines all facets of wound healing, including the kinds, pathways, and most current developments in wound treatment worldwide, particularly in silico modelling utilizing both mathematical and structure-based modelling techniques. It may be helpful to identify the crucial traits through the feedback loop of computer models and experimental investigations in order to build innovative therapies to cure wounds. Hence the effectiveness of personalised medicine and more targeted therapy in the healing of wounds may be enhanced by this interdisciplinary expertise.

Exploring the Microbial Landscape of Neonatal Skin Flora: A Comprehensive Review

This comprehensive review explores the intricate landscape of the neonatal skin microbiome, shedding light on its dynamic composition, developmental nuances, and influential factors. The neonatal period represents a critical window during which microbial colonization significantly impacts local skin health and the foundational development of the immune system. Factors such as mode of delivery and gestational age underscore the vulnerability of neonates to disruptions in microbial establishment. Key findings emphasize the broader systemic implications of the neonatal skin microbiome, extending beyond immediate health outcomes to influence susceptibility to infections, allergies, and immune-related disorders. This review advocates for a paradigm shift in neonatal care, proposing strategies to preserve and promote a healthy skin microbiome for long-term health benefits. The implications of this research extend to public health, where interventions targeting the neonatal skin microbiome could potentially mitigate diseases originating in early life. As we navigate the intersection of research and practical applications, bridging the gap between knowledge and implementation becomes imperative for translating these findings into evidence-based practices and improving neonatal well-being on a broader scale.

When the host's away, the pathogen will play: the protective role of the skin microbiome during hibernation

The skin of animals is enveloped by a symbiotic microscopic ecosystem known as the microbiome. The host and microbiome exhibit a mutualistic relationship, collectively forming a single evolutionary unit sometimes referred to as a holobiont. Although the holobiome theory highlights the importance of the microbiome, little is known about how the skin microbiome contributes to protecting the host. Existing studies focus on humans or captive animals, but research in wild animals is in its infancy. Specifically, the protective role of the skin microbiome in hibernating animals remains almost entirely overlooked. This is surprising, considering the massive population declines in hibernating North American bats caused by the fungal pathogen Pseudogymnoascus destructans, which causes white-nose syndrome. Hibernation offers a unique setting in which to study the function of the microbiome because, during torpor, the host's immune system becomes suppressed, making it susceptible to infection. We conducted a systematic review of peer-reviewed literature on the protective role of the skin microbiome in non-human animals. We selected 230 publications that mentioned pathogen inhibition by microbes residing on the skin of the host animal. We found that the majority of studies were conducted in North America and focused on the bacterial microbiome of amphibians infected by the chytrid fungus. Despite mentioning pathogen inhibition by the skin microbiome, only 30.4% of studies experimentally tested the actual antimicrobial activity of symbionts. Additionally, only 7.8% of all publications studied defensive cutaneous symbionts during hibernation. With this review, we want to highlight the knowledge gap surrounding skin microbiome research in hibernating animals. For instance, research looking to mitigate the effects of white-nose syndrome in bats should focus on the antifungal microbiome of Palearctic bats, as they survive exposure to the Pseudogymnoascus destructans -pathogen during hibernation. We also recommend future studies prioritize lesser-known microbial symbionts, such as fungi, and investigate the effects of a combination of anti-pathogen microbes, as both areas of research show promise as probiotic treatments. By incorporating the protective skin microbiome into disease mitigation strategies, conservation efforts can be made more effective.

Mesenchymal stem cells-based drug delivery systems for diabetic foot ulcer: A review

The complication of diabetes, which is known as diabetic foot ulcer (DFU), is a significant concern due to its association with high rates of disability and mortality. It not only severely affects patients’ quality of life, but also imposes a substantial burden on the healthcare system. In spite of efforts made in clinical practice, treating DFU remains a challenging task. While mesenchymal stem cell (MSC) therapy has been extensively studied in treating DFU, the current efficacy of DFU healing using this method is still inadequate. However, in recent years, several MSCs-based drug delivery systems have emerged, which have shown to increase the efficacy of MSC therapy, especially in treating DFU. This review summarized the application of diverse MSCs-based drug delivery systems in treating DFU and suggested potential prospects for the future research.

Living, quiescent Lactobacillus plantarum Lp90 probiotic, delivered topically to full thickness tissues in vitro via a just-add-water cream delivery system, stimulates the expression of elastin protein

INTRODUCTION

Delivering living probiotics to the skin can be challenging as most water-containing cosmetic products require preservatives to maintain product stability. A recently introduced powdered technology [Stratabiosys™, Vantage Personal Care] allows for quiescent probiotic powders to be stored for extended periods of time. The powders can then be reconstituted to creams at the point of use by adding water and mixing and were examined in vitro on reconstructed human full thickness tissues to see if the probiotic had any influence of several important biomolecules expressed in the skin.

MATERIALS AND METHODS

A probiotic powder containing 200 M CFU/gram of living quiescent Lactobacillus plantarum Lp90 was reconstituted to a cream by adding ultrapure water and gently mixing the components at room temperature to quickly produce a cream. The resulting cream was tested topically on Epiderm® Full Thickness Tissues by treating the tissues for 24 h, removing the cream with a PBS rinse and then repeating the treatment for another 24 h. The resulting tissues were examined for four strategically important skin biomolecules including Type 1A collagen, elastin, filaggrin and hyaluronic acid. The probiotic-containing powder was tested against untreated tissues and powders not containing probiotics and powders containing measured amounts of one of two cryoprotectants known to be used to maintain the integrity of the quiescent probiotics during drying of the quiescent probiotic powders.

RESULTS

It was found that topical treatment on Epiderm® tissues with creams containing 2 M (1%), 4 M (2%) and 6 M (3%) CFU/gram prepared from a base powder containing 200 M CFU/gram of Lactobacillus plantarum Lp90 stimulated elastin expression in a dose dependent fashion. There was no effect on the other biomolecules examined in the studies. In addition, it was found that creams made from powders containing only the known cryoprotectants, not bacteria, had no influence on elastin expression.

CONCLUSION

The results of this study demonstrate that topical delivery of probiotics is possible from powders containing quiescent probiotic powders converted to creams just prior to application to the tissues. In the case of a powder containing Lactobacillus plantarum Lp90, topical application significantly increased expression of elastin in the skin replicants after 48 h of exposure to the cream made with the probiotic. The elastin-stimulating effects are not coming from the oligosaccharide cryoprotectants used to maintain the probiotic powders in their quiescent, dried state. The results indicate that it is the living Lactobacillus plantarum probiotic that is stimulating the elastin expression in the skin tissues.

Biodiversity of Skin Microbiota as an Important Biomarker for Wound Healing

Cutaneous wound healing is a natural and complex repair process that is implicated within four stages. However, microorganisms (e.g., bacteria) can easily penetrate through the skin tissue from the wound bed, which may lead to disbalance in the skin microbiota. Although commensal and pathogenic bacteria are in equilibrium in normal skin, their imbalance in the wound area can cause the delay or impairment of cutaneous wounds. Moreover, skin microbiota is in constant crosstalk with the immune system and epithelial cells, which has significance for the healing of a wound. Therefore, understanding the major bacteria species in the cutaneous wound as well as their communication with the immune system has gained prominence in a way that allows for the emergence of a new perspective for wound healing. In this review, the major bacteria isolated from skin wounds, the role of the crosstalk between the cutaneous microbiome and immune system to heal wounds, the identification techniques of these bacteria populations, and the applied therapies to manipulate the skin microbiota are investigated.

Nanostructured Lipid Carriers Enriched Hydrogels for Skin Topical Administration of Quercetin and Omega-3 Fatty Acid

Chronic skin exposure to external hostile agents (e.g., UV radiation, microorganisms, and oxidizing chemicals) may increase oxidative stress, causing skin damage and aging. Because of their well-known skincare and protective benefits, quercetin (Q) and omega-3 fatty acids (ω3) have attracted the attention of the dermocosmetic and pharmaceutical sectors. However, both bioactives have inherent properties that limit their efficient skin delivery. Therefore, nanostructured lipid carriers (NLCs) and enriched PFC® hydrogels (HGs) have been developed as a dual-approach vehicle for Q and/or ω3 skin topical administration to improve bioactives' stability and skin permeation. Two NLC formulations were prepared with the same lipid composition but differing in surfactant composition (NLC1-soy lecithin and poloxamer 407; NLC2-Tween® 80 and dioctyl sodium sulfosuccinate (DOSS)), which have an impact on physicochemical properties and pharmaceutical and therapeutic performance. Despite both NLCs presenting high Q loading capacity, NLC2's physicochemical properties make them more suitable for topical skin administration and ensure longer colloidal stability. Additionally, NLC2 demonstrated a more sustained Q release, indicating higher bioactive storage while improving permeability. The occlusive effect of NLCs-enriched HGs also has a positive impact on skin permeability. Q-loaded NLC2, with or without ω3, -enriched HGs demonstrated efficacy as antioxidant and photoprotective formulations as well as effective reduction in S. aureus growth, indicating that they constitute a promising approach for topical skin administration to prevent skin aging and other damaging cutaneous processes.

Bioprospecting the Skin Microbiome: Advances in Therapeutics and Personal Care Products

Bioprospecting is the discovery and exploration of biological diversity found within organisms, genetic elements or produced compounds with prospective commercial or therapeutic applications. The human skin is an ecological niche which harbours a rich and compositional diversity microbiome stemming from the multifactorial interactions between the host and microbiota facilitated by exploitable effector compounds. Advances in the understanding of microbial colonisation mechanisms alongside species and strain interactions have revealed a novel chemical and biological understanding which displays applicative potential. Studies elucidating the organismal interfaces and concomitant understanding of the central processes of skin biology have begun to unravel a potential wealth of molecules which can exploited for their proposed functions. A variety of skin-microbiome-derived compounds display prospective therapeutic applications, ranging from antioncogenic agents relevant in skin cancer therapy to treatment strategies for antimicrobial-resistant bacterial and fungal infections. Considerable opportunities have emerged for the translation to personal care products, such as topical agents to mitigate various skin conditions such as acne and eczema. Adjacent compound developments have focused on cosmetic applications such as reducing skin ageing and its associated changes to skin properties and the microbiome. The skin microbiome contains a wealth of prospective compounds with therapeutic and commercial applications; however, considerable work is required for the translation of in vitro findings to relevant in vivo models to ensure translatability.

Receptors and Cofactors That Contribute to SARS-CoV-2 Entry: Can Skin Be an Alternative Route of Entry?

To prevent the spread of SARS-CoV-2, all routes of entry of the virus into the host must be mapped. The skin is in contact with the external environment and thus may be an alternative route of entry to transmission via the upper respiratory tract. SARS-CoV-2 cell entry is primarily dependent on ACE2 and the proteases TMPRSS2 or cathepsin L but other cofactors and attachment receptors have been identified that may play a more important role in specific tissues such as the skin. The continued emergence of new variants may also alter the tropism of the virus. In this review, we summarize current knowledge on these receptors and cofactors, their expression profile, factors modulating their expression and their role in facilitating SARS-CoV-2 infection. We discuss their expression in the skin and their possible involvement in percutaneous infection since the presence of the virus has been detected in the skin.