Evolution of the facial skin microbiome during puberty in normal and acne skin

Intraspecies dynamics underlie the apparent stability of two important skin microbiome species

Adult human facial skin microbiomes are remarkably similar at the species level, dominated by Cutibacterium acnes and Staphylococcus epidermidis, yet each person harbors a unique community of strains. Understanding how person-specific communities assemble is critical for designing microbiome-based therapies. Here, using 4,055 isolate genomes and 356 metagenomes, we reconstruct on-person evolutionary history to reveal on- and between-person strain dynamics. We find that multiple cells are typically involved in transmission, indicating ample opportunity for migration. Despite this accessibility, family members share only some of their strains. S. epidermidis communities are dynamic, with each strain persisting for an average of only 2 years. C. acnes strains are more stable and have a higher colonization rate during the transition to an adult facial skin microbiome, suggesting this window could facilitate engraftment of therapeutic strains. These previously undetectable dynamics may influence the design of microbiome therapeutics and motivate the study of their effects on hosts.

Disrupting the balance: how acne duration impacts skin microbiota assembly processes

Growing interest in the impact of microbial balance on health has driven studies on the ecological processes shaping the skin microbiota. Skin diseases, which alter the skin's local environment, can disrupt the microbial structure and interact with the disease itself. However, research on microbial assembly in diseased skin remains limited. In this study, we applied ecological models to characterize the processes shaping the skin microbiota in acne patients, considering the impact of disease duration on both skin pores and surfaces using bacterial amplicon sequencing. Our results revealed a significant shift in microbial diversity on the skin surface of patients with long-term acne. Further microbial community analyses showed a transition in ecological processes from healthy to diseased skin. Microbial communities on the skin surfaces of healthy controls and individuals with short-duration acne were primarily driven by heterogeneous selection, whereas microbial drift dominated the assembly process in the long-duration groups. Using the Sloan neutral model, we classified amplicon sequence variants (ASVs) into high-effect and low-effect groups based on relative abundance and sample occurrence. High-effect ASVs, likely exerting a greater ecological influence, were predominantly represented by Cutibacterium across all acne-affected skin groups, while Staphylococcus became enriched among high-effect ASVs in patients with long-term acne. Functional profiling further demonstrated that high-effect ASVs were significantly enriched in motility-related pathways. Additionally, we observed a reduction in microbial network complexity on skin surfaces as disease duration increased. Overall, the ecological dynamics of skin microbial communities may offer valuable insights into the mechanisms underlying disease onset and persistence.IMPORTANCEThe skin microbiota plays a critical role in acne development, yet the processes governing microbial assembly during acne progression remain poorly understood. Previous studies predominantly focused on factors such as acne severity, location, and duration in relation to skin microbial structure, with little attention given to the ecological mechanisms shaping the communities. In this study, we applied ecological models to investigate the processes influencing microbial assembly of skin microbiota in acne patients with varying disease durations and examined functions of ecologically important non-neutral amplicon sequence variants (ASVs). Our findings reveal a transition in ecological processes from deterministic to neutral processes as acne duration increased, with non-neutral ASVs potentially contributing to acne pathogenicity and persistence. These insights contribute to a deeper understanding of the ecological dynamics underlying acne and indicate that targeting these non-neutral ASVs or their associated functions may serve as the basis for future therapeutic strategies.

Acne and the cutaneous microbiome: A systematic review of mechanisms and implications for treatments

BACKGROUND

Acne vulgaris is a pervasive skin disease characterized by inflammation of sebaceous units surrounding hair follicles. It results from the complex interplay between skin physiology and the intricate cutaneous microbiome. Current acne treatments, while effective, have major limitations, prompting a shift towards microbiome-based therapeutic approaches.

OBJECTIVES

This study aims to determine the relationship between acne and the cutaneous microbiome, assess the effects of current treatments on the cutaneous microbiome, and explore the implications for developing new therapies.

METHODS

A systematic review was performed using PubMed and SCOPUS databases within the last 10 years. Methodological quality was assessed independently by two authors. The search retrieved 1830 records, of which 26 articles met the inclusion criteria. Meta-analysis of alpha diversity change was assessed using fixed and randomized effect models per therapeutic group.

RESULTS

Eight studies pertain to the role of the cutaneous microbiome in acne, identifying C. acnes, S. aureus and S. epidermidis as key contributors through overproliferation, commensalism, or dysbiosis. Eleven studies discuss current acne treatments, including doxycycline (1), topical benzoyl peroxide (BPO) (4), isotretinoin (2), sulfacetamide-sulfur (SSA) (2) and aminolevulinic acid-photodynamic therapy (ALA-PDT) (2), identified as modulating the cutaneous microbiome as a mechanism of efficacy in acne treatment. Seven studies discuss new treatments with topical probiotics, plant derivatives, and protein derivatives, which contribute to acne clearance via modulation of dysbiosis, inflammatory markers and diversity indexes. A meta-analysis of the effects of existing therapeutics on the cutaneous microbiome identified benzoyl peroxide as the only treatment to facilitate significant change in diversity.

CONCLUSIONS

Despite the heterogeneity of study types and microbiome classifications limiting the analysis, this review underscores the complexity of microbial involvement in acne pathogenesis. It delineates the effects of acne therapeutics on microbial diversity, abundance, and composition, emphasizing the necessity for personalized approaches in acne management based on microbiome modulation.

Amplicon-based analysis reveals link between adolescent acne and altered facial skin microbiome induced by negative emotional states

Introduction

The skin microbiome is integral to maintaining skin homeostasis and is involved in the pathogenesis of acne. Emerging evidence supporting the 'brain-skin axis' suggests that psychological stress may exacerbate acne. Both negative emotional states and acne are highly prevalent among adolescents. Although research has begun to explore this relationship, the role of the skin microbiome in adolescents experiencing emotional disturbances and acne remains poorly understood.

Methods

166 adolescents aged 15-18 were divided into four distinct groups based on their emotional health and acne severity: no acne or negative emotions (NC), acne without negative emotions (NS), negative emotions without acne (YC), and acne with negative emotions (YS). Skin samples were collected from each participant's forehead and analyzed using high-throughput sequencing techniques, followed by comprehensive bioinformatics analyses to evaluate the microbial composition and diversity across the different groups.

Results

Adolescents with both acne and negative emotions exhibited significantly higher acne severity (IGA 2.675 ± 0.090) compared to the group with acne but without negative emotions (IGA 1.952 ± 0.136). Distinct microbial community patterns emerged among the groups, with acne-affected individuals displaying increased α-diversity. Additionally, negative emotions were associated with heightened β-diversity differences between acne-affected individuals. The predominant bacterial phyla identified were Firmicutes, Bacteroidetes, Proteobacteria, and Fusobacteria, with Acinetobacter being more abundant, and Roseomonas and Cutibacterium being less prevalent in adolescents experiencing negative emotions.

Conclusion

This study revealed that the bacterial biomarkers of the disease change when acne is accompanied by negative emotions. Cutibacterium, Acinetobacter, and Roseomonas may be key contributors to acne exacerbation. These findings underscore the importance of considering both emotional and microbiological factors in the management of adolescent acne, particularly within the context of the brain-skin connection.

Skin microbiome and dermatologic disorders

Human skin acts as a physical barrier to prevent the entry of pathogenic microbes while simultaneously providing a home for commensal bacteria and fungi. Microbiome sequencing studies have demonstrated the unappreciated diversity and selectivity of these microbes. Functional studies have demonstrated the impact of specific strains to tune the immune system, sculpt the microbial community, provide colonization resistance, and promote epidermal barrier integrity. Recent studies have integrated the microbiome, immunity, and tissue integrity to understand their interplay in common disorders such as atopic dermatitis. In this Review, we explore microbiome shifts associated with cutaneous disorders with an eye toward how the microbiome can be mined to identify new therapeutic opportunities.

Hypocrellin A-mediated photodynamic antibacterial activity against Cutibacterium acnes: An in vitro study

Skin dysbiosis caused by Cutibacterium acnes contributes greatly to the complex pathogenesis of acne, and antimicrobial photodynamic therapy (PDT) has emerged as a promising treatment option for acne treatment. Hypocrellin, a photosensitizer extracted from a traditional Chinese medicinal fungus, has showed effective antimicrobial activity. This study aimed to evaluate the antibacterial ability of hypocrellin mediated PDT against Cutibacterium acnes. Using modified broth dilution method and morphological observation, the antibacterial effect was tested under a series of experimental conditions. The results showed that hypocrellin initiates type II photodynamic reactions by inducing amount of reactive oxygen species, particularly singlet oxygen. Within a certain concentration range, hypocrellin effectively maintained the antibacterial efficacy with minimal damage to keratinocyte cells. These results provide new insights into the use of PDT for acne treatment.

Previously hidden intraspecies dynamics underlie the apparent stability of two important skin microbiome species

Adult human facial skin microbiomes are remarkably similar at the species-level, dominated by Cutibacterium acnes and Staphylococcus epidermidis, yet each person harbors a unique community of strains. Understanding how person-specific communities assemble is critical for designing microbiome-based therapies. Here, using 4,055 isolate genomes and 360 metagenomes, we reconstruct on-person evolutionary history to reveal on and between-person strain dynamics. We find that multiple cells are typically involved in transmission, indicating ample opportunity for migration. Despite this accessibility, family members share only some of their strains. S. epidermidis communities are dynamic, with each strain persisting for an average of only 2 years. C. acnes strains are more stable and have a higher colonization rate during the transition to an adult facial skin microbiome, suggesting this window could facilitate engraftment of therapeutic strains. These previously undetectable dynamics may influence the design of microbiome therapeutics and motivate the study of their effects on hosts.

Distinct Intraspecies Variation of Cutibacterium acnes and Staphylococcus epidermidis in Acne Vulgaris and Healthy Skin

Human skin hosts a diverse array of microorganisms that contribute to its health. Key players in the facial skin microbiome include Cutibacterium acnes and staphylococci, whose colonization patterns may influence dermatological conditions like acne vulgaris. This study examined the facial microbiome composition of 29 individuals, including 14 with moderate to severe acne and 15 with healthy skin, using single locus sequence typing (SLST) amplicon sequencing. The results showed a shift in the relative abundances of C. acnes phylotypes: SLST types A, C, and F were increased in acne, while types H, K, and L were reduced compared to healthy skin. Among staphylococci, the relative abundance of S. epidermidis, S. capitis, and S. saphrophyticus increased in acne, while S. saccharolyticus and S. hominis decreased. The amplicon sequencing approach could also identify a population shift of S. epidermidis: a specific S. epidermidis phylogenetic lineage (type 3) was reduced in acne, while two abundant lineages (types 1 and 2) were elevated. These findings suggest that distinct phylogenetic lineages of both C. acnes and S. epidermidis are linked to healthy versus diseased skin, highlighting a potential role for both microorganisms in disease prevention and aggravation, respectively.

Association Between Scalp Microbiota Imbalance, Disease Severity, and Systemic Inflammatory Markers in Alopecia Areata

INTRODUCTION

Alopecia areata (AA) is an autoimmune disease causing non-scarring hair loss, with both genetic and environmental factors implicated. Recent research highlights a possible role for scalp microbiota in influencing both local and systemic inflammatory responses, potentially impacting AA progression. This study examines the link among scalp microbiota imbalances, AA severity, and systemic inflammation.

METHODS

We conducted a cross-sectional study with 24 participants, including patients with AA of varying severities and healthy controls. Scalp microbial communities were analyzed using swab samples and ion torrent sequencing of the 16S rRNA gene across multiple hypervariable regions. We explored correlations among bacterial abundance, microbiome metabolic pathways, and circulating inflammatory markers.

RESULTS

Our findings reveal significant dysbiosis in the scalp microbiota of patients with AA compared to healthy controls. Severe AA cases had an increased presence of pro-inflammatory microbial taxa like Proteobacteria, whereas milder cases had higher levels of anti-inflammatory Actinobacteria. Notable species differences included abundant gram-negative bacteria such as Alistipes inops and Bacteroides pleibeius in severe AA, contrasted with Blautia faecis and Pyramydobacter piscolens predominantly in controls. Significantly, microbial imbalance correlated with AA severity (SALT scores) and systemic inflammatory markers, with elevated pro-inflammatory cytokines linked to more severe disease.

CONCLUSION

These results suggest that scalp microbiota may play a role in AA-related inflammation, although it is unclear whether the shifts are a cause or consequence of hair loss. Further research is needed to clarify the causal relationship and mechanisms involved.

The inner elbow skin microbiome contains Lactobacillus among its core taxa and varies with age, season and lifestyle

Background: The human skin microbiome plays an essential role in protecting against pathogens and other external substances. This open ecosystem is also influenced by personal and environmental factors, but the precise impact of these factors, such as lifestyle and season, is understudied. We focused here on the inner elbow, a skin site prone to inflammatory conditions like atopic dermatitis and psoriasis. Methods: We collected skin swabs from the inner elbow of 52 children and adults, with no signs of skin disorders, in the winter and summer seasons. Samples were analyzed using metagenomic shallow shotgun sequencing. In addition, metadata were collected using questionnaires on health, lifestyle, and environmental factors. Results: The core inner elbow community, taxa with a prevalence of 95% or higher, consisted of several well-known skin taxa, such as Staphylococcus hominis, Staphylococcus capitis, Staphylococcus epidermidis, and Cutibacterium acnes. In addition, Streptococcus and Lactobacillus species were also found to be highly prevalent members of the skin microbiota, especially in the age group up to 3 years old. Of all investigated factors, age appeared to be the major driver defining the skin microbiome composition and longitudinal stability over the seasons. Differential abundance analysis using three statistical tests also pointed out that specific skin species were significantly associated with sampling season, age, hygiene practices, vitamin D supplements, probiotics, and the number of household members. Conclusion: This study identifies novel factors influencing the inner elbow skin microbiome composition and paves the way for future comparative and intervention studies in skin disorders such as atopic dermatitis.

Alterations in the Skin Microbiome in Dermatologic Diseases and with External Exposures: CME Part 2

In Part I of our CME we reviewed the skin microbiome in healthy individuals. Part II reviews the evolving understanding of alterations in the skin microbiome in specific human diseases. We also discuss how the skin microbiome can change with environmental exposures and medications such as antibiotics as well as ongoing research on microbiome-based interventions.

The Human Skin Microbiome in Health: CME Part 1

Human skin is home to a myriad of microorganisms, including bacteria, viruses, fungi, and mites, many of which are considered commensal microbes that aid in maintaining the overall homeostasis or steady-state condition of the skin and contribute to skin health. Our understanding of the complexities of the skin's interaction with its microorganisms is evolving. This knowledge is based primarily on in vitro and animal studies, and more work is needed to understand how this knowledge relates to humans. Here, we introduce the concept of the skin microbiome and discuss skin microbial ecology, some intrinsic factors with potential influence on the human skin microbiome, and possible microbiome-host interactions. The second article of this two-part CME series describes how microbiome alterations may be associated with skin disease, how medications can affect the microbiome, and what microbiome-based therapies are under investigation.

Characterization of the forehead skin microbiome in the early phase of acne

BACKGROUND

The skin microbiota is known to be imbalanced in acne vulgaris, but the changes occurring during the early stages of acne onset remain poorly described.

OBJECTIVES

To characterize the skin microbiome of subclinical stages of acne in adults and adolescents.

METHODS

The composition and diversity of the microbiota from non-lesional skin on the forehead of subjects with mild-to-moderate acne were compared to the ones from non-acne subjects. Analyses of skin swab samples were performed using high-throughput sequencing of the V1-V3 regions of the bacterial 16S ribosomal RNA gene, the tuf gene fragment of Staphylococcus species and the internal transcribed spacer (ITS1) region of the fungal rRNA gene to determine the relative abundance, alpha-diversity and beta-diversity of bacteria and fungi.

RESULTS

Compared with non-acne subjects, acne subjects had a higher abundance of Cutibacterium (72.4% vs. 57.8%) and lower abundances of Corynebacterium (2.8% vs. 4.8%) and Streptococcus (1.4% vs. 3.2%). Bacterial alpha- and beta-diversity indices also differed significantly between the two groups, reflecting differences in richness, evenness, abundance and phylogenetic distance between bacterial populations. Differences were also observed at the level of Staphylococcus species: S. capitis was predominant in skin samples from non-acne subjects (46.7%), whereas S. epidermidis was the most abundant Staphylococcus species in non-lesional forehead skin areas of acne subjects (44.2%). Conversely, no significant between-group differences were found for fungi, with Malasseziales being the predominant order in both subject groups.

CONCLUSION

Dysbiosis was observed very early in subclinical acne stages of the forehead skin, with the overall abundance, richness and evenness of the bacterial population being lower in acne than in non-acne skin samples. Dysbiosis was also found at the level of Staphylococcus species. The development of acne lesions could therefore be prevented by using a skin care product that rebalances facial skin microbiota at very early stages.

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.

Spectral characterization of a blue light-emitting micro-LED platform on skin-associated microbial chromophores

The therapeutic application of blue light (380 - 500nm) has garnered considerable attention in recent years as it offers a non-invasive approach for the management of prevalent skin conditions including acne vulgaris and atopic dermatitis. These conditions are often characterised by an imbalance in the microbial communities that colonise our skin, termed the skin microbiome. In conditions including acne vulgaris, blue light is thought to address this imbalance through the selective photoexcitation of microbial species expressing wavelength-specific chromophores, differentially affecting skin commensals and thus altering the relative species composition. However, the abundance and diversity of these chromophores across the skin microbiota remains poorly understood. Similarly, devices utilised for studies are often bulky and poorly characterised which if translated to therapy could result in reduced patient compliance. Here, we present a clinically viable micro-LED illumination platform with peak emission 450 nm (17 nm FWHM) and adjustable irradiance output to a maximum 0.55 ± 0.01 W/cm2, dependent upon the concentration of titanium dioxide nanoparticles applied to an accompanying flexible light extraction substrate. Utilising spectrometry approaches, we characterised the abundance of prospective blue light chromophores across skin commensal bacteria isolated from healthy volunteers. Of the strains surveyed 62.5% exhibited absorption peaks within the blue light spectrum, evidencing expression of carotenoid pigments (18.8%, 420-483 nm; Micrococcus luteus, Kocuria spp.), porphyrins (12.5%, 402-413 nm; Cutibacterium spp.) and potential flavins (31.2%, 420-425 nm; Staphylococcus and Dermacoccus spp.). We also present evidence of the capacity of these species to diminish irradiance output when combined with the micro-LED platform and in turn how exposure to low-dose blue light causes shifts in observed absorbance spectra peaks. Collectively these findings highlight a crucial deficit in understanding how microbial chromophores might shape response to blue light and in turn evidence of a micro-LED illumination platform with potential for clinical applications.

Understanding Type 3 Innate Lymphoid Cells and Crosstalk with the Microbiota: A Skin Connection

Innate lymphoid cells (ILCs) are a diverse population of lymphocytes classified into natural killer (NK) cells, ILC1s, ILC2s, ILC3s, and ILCregs, broadly following the cytokine secretion and transcription factor profiles of classical T cell subsets. Nonetheless, the ILC lineage does not have rearranged antigen-specific receptors and possesses distinct characteristics. ILCs are found in barrier tissues such as the skin, lungs, and intestines, where they play a role between acquired immune cells and myeloid cells. Within the skin, ILCs are activated by the microbiota and, in turn, may influence the microbiome composition and modulate immune function through cytokine secretion or direct cellular interactions. In particular, ILC3s provide epithelial protection against extracellular bacteria. However, the mechanism by which these cells modulate skin health and homeostasis in response to microbiome changes is unclear. To better understand how ILC3s function against microbiota perturbations in the skin, we propose a role for these cells in response to Cutibacterium acnes, a predominant commensal bacterium linked to the inflammatory skin condition, acne vulgaris. In this article, we review current evidence describing the role of ILC3s in the skin and suggest functional roles by drawing parallels with ILC3s from other organs. We emphasize the limited understanding and knowledge gaps of ILC3s in the skin and discuss the potential impact of ILC3-microbiota crosstalk in select skin diseases. Exploring the dialogue between the microbiota and ILC3s may lead to novel strategies to ameliorate skin immunity.

A review of skin immune processes in acne

Acne vulgaris is one of the most prevalent skin conditions, affecting almost all teenagers worldwide. Multiple factors, including the excessive production of sebum, dysbiosis of the skin microbiome, disruption of keratinization within hair follicles, and local inflammation, are believed to trigger or aggravate acne. Immune activity plays a crucial role in the pathogenesis of acne. Recent research has improved our understanding of the immunostimulatory functions of microorganisms, lipid mediators, and neuropeptides. Additionally, significant advances have been made in elucidating the intricate mechanisms through which cutaneous innate and adaptive immune cells perceive and transmit stimulatory signals and initiate immune responses. However, our understanding of precise temporal and spatial patterns of immune activity throughout various stages of acne development remains limited. This review provides a comprehensive overview of the current knowledge concerning the immune processes involved in the initiation and progression of acne. Furthermore, we highlight the significance of detailed spatiotemporal analyses, including analyses of temporal dynamics of immune cell populations as well as single-cell and spatial RNA sequencing, for the development of targeted therapeutic and prevention strategies.

A cross-sectional cohort study on the skin microbiota in patients with different acne durations

Acne is a chronic disease that often persists for years. Skin microbial communities play an essential role in the development of acne. However, limited information is available about the dynamic patterns of skin microbiota in acne. This study aimed to characterize microbial community changes in skin pores and surfaces of acne patients with varying disease time. In this study, a total of 70 skin samples from 22 subjects were collected and sequenced using 16S rRNA amplicon sequencing. Although microbial compositions in skin pores were similar over time, significant differences in microbial structure were observed on the skin surface, with the dominance of Cutibacterium in the first 3 years and replacement by Staphylococcus in 4-6 years. Lactobacillus and Acinetobacter were more abundant in the normal group and continuingly decreased with disease time on the skin surface. Microbial networks further revealed substantial increases in microbial interactions in the 4-6 years group in both skin surfaces and pores. These results demonstrate that the skin microbiota alters with the disease duration and may provide a potential guide in redirecting skin microbiota towards healthy states.

The updates and implications of cutaneous microbiota in acne

Acne is a chronic inflammatory skin disorder that profoundly impacts the quality of life of patients worldwide. While it is predominantly observed in adolescents, it can affect individuals across all age groups. Acne pathogenesis is believed to be a result of various endogenous and exogenous factors, but the precise mechanisms remain elusive. Recent studies suggest that dysbiosis of the skin microbiota significantly contributes to acne development. Specifically, Cutibacterium acnes, the dominant resident bacterial species implicated in acne, plays a critical role in disease progression. Various treatments, including topical benzoyl peroxide, systemic antibiotics, and photodynamic therapy, have demonstrated beneficial effects on the skin microbiota composition in acne patients. Of particular interest is the therapeutic potential of probiotics in acne, given its direct influence on the skin microbiota. This review summarizes the alterations in skin microbiota associated with acne, provides insight into its pathogenic role in acne, and emphasizes the potential of therapeutic interventions aimed at restoring microbial homeostasis for acne management.

The Skin Microbiome: Current Landscape and Future Opportunities

Our skin is the largest organ of the body, serving as an important barrier against the harsh extrinsic environment. Alongside preventing desiccation, chemical damage and hypothermia, this barrier protects the body from invading pathogens through a sophisticated innate immune response and co-adapted consortium of commensal microorganisms, collectively termed the microbiota. These microorganisms inhabit distinct biogeographical regions dictated by skin physiology. Thus, it follows that perturbations to normal skin homeostasis, as occurs with ageing, diabetes and skin disease, can cause microbial dysbiosis and increase infection risk. In this review, we discuss emerging concepts in skin microbiome research, highlighting pertinent links between skin ageing, the microbiome and cutaneous repair. Moreover, we address gaps in current knowledge and highlight key areas requiring further exploration. Future advances in this field could revolutionise the way we treat microbial dysbiosis associated with skin ageing and other pathologies.

New insights into the characteristic skin microorganisms in different grades of acne and different acne sites

Background

The increasing maturity of sequencing technology provides a convenient approach to studying the role of skin microorganisms in acne pathogenesis. However, there are still too few studies about the skin microbiota of Asian acne patients, especially a lack of detailed analysis of the characteristics of the skin microbiota in the different acne sites.

Methods

In this study, a total of 34 college students were recruited and divided into the health, mild acne, and severe acne groups. The bacterial and fungal flora of samples were separately detected by 16S and 18S rRNA gene sequencing. The biomarkers of different acne grades and different acne sites [forehead, cheek, chin, torso (including chest and back)] were excavated.

Results and Discussion

Our results indicated that there was no significant difference in species diversity between groups. The genera like Propionibacterium, Staphylococcus, Corynebacterium, and Malassezia, which have a relatively high abundance in the skin microbiota and were reported as the most acne-associated microbes, were no obvious differences between groups. On the contrary, the abundance of less reported Gram-negative bacteria (Pseudomonas, Ralstonia, and Pseudidiomarina) and Candida has a significant alteration. Compared with the health group and the mild group, in the severe group, the abundance of Pseudomonas and Ralstonia sharply reduced while that of Pseudidiomarina and Candida remarkably raised. Moreover, different acne sites have different numbers and types of biomarkers. Among the four acne sites, the cheek has the greatest number of biomarkers including Pseudomonas, Ralstonia, Pseudidiomarina, Malassezia, Saccharomyces, and Candida, while no biomarker was observed for the forehead. The network analysis indicated that there might be a competitive relationship between Pseudomonas and Propionibacterium. This study would provide a new insight and theoretical basis for precise and personalized acne microbial therapy.