Acne microbiome: From phyla to phylotypes

From Monotherapy to Adjunctive Therapies: Application of Dermocosmetics in Acne Management Across Australia and New Zealand

Acne vulgaris is a globally prevalent dermatological disease, with its severity ranging from mild to severe. While moderate to severe acne often requires topical or systemic pharmaceutical therapy, mild to moderate acne may be managed with dermocosmetics, which are over-the-counter skincare agents with active ingredients that target acne pathophysiology. Dermocosmetics can also be effective as adjunct therapy for the management of more severe acne. For example, they can be used to complement the mode of action of pharmaceuticals or to mitigate side effects and improve treatment compliance. This review discusses the roles of commonly available dermocosmetics in the context of both mild and severe acne management protocols.

Harnessing the Power of Alchemilla: A Natural Solution for Skin Health and Dermatological Disorders

Skin diseases are prevalent and encompass a wide range of disorders with varying clinical manifestations and diverse etiopathogenesis. The response to the necessity of multidirectional treatment is provided by species belonging to the genus Alchemilla, which is used in traditional medicine as well as in cosmetic formulations. Responsible for the healing properties of these plants for skin diseases are mainly compounds such as tannins, phenolic acids, flavonoids, and anthocyanins. The aim of the study was to analyze and synthesize the published literature on the Alchemilla species in skincare with a timeframe of December 2024. The literature indicates that due to antioxidant, anti-inflammatory, astringent, antimicrobial, elastase activity and tyrosinase inhibitory properties of various Alchemilla species, extracts obtained from these plants can be successfully applied in skin rashes, acne, stretch marks, eczema, psoriasis, wrinkles and other dermatological issues. To the best of our knowledge, this is the first review of the cosmetic activities of Alchemilla species.

Development of a self-assembled micelles based on cryptotanshinone and glycyrrhizic acid: An efficient strategy for acne treatment

Acne vulgaris is a prevalent inflammatory skin disease affecting the folliculosebaceous unit. Current treatments, such as antibiotics and anti-inflammatory drugs, face challenges like drug resistance and side effects. Cryptotanshinone (CTS), a diterpenoid from Salvia miltiorrhiza, exhibits potential acne-treating effects by inhibiting sebaceous gland secretion, regulating perifollicular keratosis and exhibiting anti-inflammatory properties. However, its poor water solubility and skin permeability hinder clinical application. CTS was researched in the previous work and CTS cerasomes was prepared. However, the issues of low encapsulation rate and large particle size still existed. Here, we propose a strategy for encapsulating CTS using a glycyrrhizin-based carrier to address the issues above. Under microscopic observation, the glycyrrhizic acid-encapsulated CTS micelles (GA-CTS), with an average size of 24.81 ± 1.40 nm, exhibited a uniform spherical shape. In vitro permeation assay demonstrated that the water solubility and skin permeability of CTS were significantly improved, indicating a higher bioavailability. GA-CTS also inhibited Cutibacterium acnes (C. acnes) and reduced Tumor Necrosis Factor-α (TNF-α) and Interleukin-1β (IL-1β) expression in HaCaT cells. In vivo, a BALB/c mouse acne model was established via intradermal C. acnes injection. HE staining, IL-1β immunohistochemistry, and qRT-PCR were used to assess the treatment effect of GA-CTS. Compared to CTS or GA alone, GA-CTS significantly inhibited C. acnes growth, reduced skin swelling, and improved skin histology. Notably, GA-CTS inhibited keratin 16 (K16) gene expression, improving abnormal skin keratinization, and regulated 5-α reductase mRNA expression, potentially impacting androgen metabolism and offering another mechanism for acne treatment. In conclusion, GA-CTS micelles show promising potential in acne treatment, offering new insights and methods for anti-acne drug development and clinical application.

Microbe-Host Interaction in Rosacea and Its Modulation through Topical Ivermectin

Rosacea is characterized by inflammatory lesions, often accompanied by an increased density of the common skin mite Demodex folliculorum. Although rosacea shows a high prevalence and significantly affects the QOL of patients, the underlying mechanisms, especially the role of cutaneous dysbiosis, are largely unknown. Hence, we aimed to systematically characterize disease severity of patients with rosacea in the context of mite density, the cutaneous microbiome, and the host's transcriptome before and after 30 days of topical 1% ivermectin cream treatment. At day 30, a marked decrease in mite density was observed in 87.5% of patients. At day 0, distinct microbial community changes included the decrease in Cutibacterium acnes abundance, whereas Staphylococcus epidermidis colonization increased compared with that in healthy volunteers. Interestingly, the insect symbiont Snodgrassella alvi was recovered from a highly Demodex-colonized patient and eradicated by treatment on day 30. Although topical ivermectin did not affect bacterial dysbiosis, the host's transcriptome significantly normalized, and an "ivermectin transcriptomic signature" was defined. Findings of this study support that rosacea lesions are associated with dysbiosis. However, improvement of clinical signs during topical ivermectin is not associated with normalization of the bacterial microbiome but rather a decrease of transcriptomic dysregulation and mite density.

Multi-target mechanisms and potential applications of quercetin in the treatment of acne vulgaris

Acne vulgaris, a prevalent inflammatory dermatosis, afflicts approximately 90% of adolescents globally. Despite the efficacy of conventional therapies, including antibiotics and retinoids, their use is frequently limited by adverse effects and the emergence of drug resistance. Quercetin, a naturally occurring flavonoid, has garnered significant attention owing to its diverse biological activities, encompassing anti-inflammatory, antioxidant, antimicrobial, and immunomodulatory properties. This review comprehensively explores the multi-target mechanisms of quercetin in the treatment of acne, focusing on its ability to modulate inflammatory cytokine production, oxidative stress pathways, sebaceous gland activity, and microbial populations. Additionally, quercetin promotes skin barrier repair and reduces post-inflammatory hyperpigmentation and scarring through its antioxidant and anti-fibrotic effects. Despite promising in vitro and preclinical findings, challenges such as quercetin's low bioavailability and lack of robust clinical evidence necessitate further research. Advanced delivery systems, including nanoparticles and combination therapies, may optimize its therapeutic potential. This review provides insights into the molecular mechanisms and clinical applications of quercetin, highlighting its potential as a safe and effective alternative for acne management.

Efficacy and safety of the 589/1319 nm solid-state dual-wavelength laser combined with topical benzoyl peroxide for inflammatory acne vulgaris: a split-face randomized controlled trial

The 589/1319 nm solid-state dual-wavelength (SSDW) laser, which does not require consumable dye, has the potential to target inflammation and sebum production in acne vulgaris pathogenesis. To assess the efficacy and safety of 598/1319 nm SSDW laser as an adjunctive treatment to conventional treatment, 18 patients with bilateral facial acne, with inflammatory papules or pustules, were recruited. Patients were instructed to apply 2.5% benozoyl peroxide (BPO), the drug for inflammatory acne, to their entire face throughout the study. One side of the face was randomly assigned to receive 4 sessions of 589/1319 nm SSDW laser treatments, administered every 2 weeks. After the last laser treatment, 3 monthly follow-ups were scheduled. Inflammatory lesion count (ILC) and acne-related skin parameters, including hemoglobin level, melanin level, skin depression, and skin roughness were measured. Adverse events (AEs) and patients' satisfaction were assessed. At the 3-month follow-up, the ILC reduced by 46% on the adjunctive laser (BPO + laser) side (p = 0.0080), compared with a 29% reduction on the BPO monotherapy side (p = 0.1875). On the adjunctive laser side, the change in ILC positively correlated with the change in melanin level (r = 0.51, p = 0.0301) and showed a trend towards a positive correlation with the change in depression volume (r = 0.45, p = 0.0606) and roughness level (r = 0.42, p = 0.0806). The patients reported a pain score of 3.4 ± 2.3 on scale of 10. No serious AEs occurred. Patients' satisfaction scores were higher with the adjunctive laser therapy, although this was not statistically significant (p = 0.2758). In conclusion, the 589/1319 nm SSDW laser provided a synergistic effect as an adjunctive treatment to BPO in inflammatory acne in terms of reducing ILC and improving post inflammatory hyperpigmentation without causing discomfort or downtime.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Synthetically programmed antioxidant delivery by a domesticated skin commensal

Bacteria represent a promising dynamic delivery system for the treatment of disease. In the skin, the relevant location of Cutibacterium acnes within the hair follicle makes this bacterium an attractive chassis for dermal biotechnological applications. Here, we provide a genetic toolbox for the engineering of this traditionally intractable bacterium, including basic gene expression tools, biocontainment strategies, markerless genetic engineering, and dynamic transcriptional regulation. As a proof of concept, we develop an antioxidant-secreting strain capable of reducing oxidative stress in a UV stress model.

Comparative efficacy of essential oils against Cutibacterium acnes: Effect upon strains from phylotypes with different virulence patterns

OBJECTIVES

Despite being a commensal of human skin, Cutibacterium acnes plays an important role in the pathogenesis of Acne vulgaris, with the loss of bacterial phylotype diversity being related to disease progression. This study evaluated differences in the virulence profile of C. acnes strains from different phylotypes and investigated the possible phylotype-selective efficacy of essential oils (EOs) from Thymus x citriodorus (TC), Thymus mastichina, and Cistus ladanifer compared to Melaleuca alternifolia (tea tree), focusing on both planktonic and biofilm growth forms, the latter being related with pathogenesis and treatment resistance.

METHODS

One collection strain and seven clinical isolates were classified into phylotypes using multiplex-touchdown PCR. Virulence trait differences across phylotypes were evaluated by studying antibiotic resistance, biofilm formation, porphyrin production, and lipase activity. EOs were tested for minimum inhibitory/bactericidal concentrations (MIC/MBC) and effects on biofilm biomass and metabolic activity.

RESULTS

Strains from phylotype IA1 were higher biofilm and lipase producers than phylotype II strains. Regarding EO's efficacy, TC EO presented lower planktonic MIC values for all strains compared to the other EOs, presenting a smaller difference in MIC values across phylotypes. TC EO was able to similarly reduce biofilm biomass and metabolic activity in phylotype IA1 clinical strains, being effective at lower concentrations compared with the remaining EOs.

CONCLUSIONS

Not all virulence traits were phylotype-related, highlighting the multifactorial nature of the disease. TC EO showed a relevant anti-acne potential, outperforming tea tree EO (a species with a commercial claim for Acne vulgaris) against both planktonic and biofilm growth forms of C. acnes.

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.

Vaccines in Dermatology-Present and Future: A Review

Dermatological vaccines have emerged as critical tools in preventing and managing a wide spectrum of skin conditions ranging from infectious diseases to malignancies. By synthesizing evidence from existing literature, this review aims to comprehensively evaluate the efficacy, safety, and immunogenicity of vaccines used in dermatology, including both approved vaccines and those currently being researched. Vaccines discussed in this paper include those targeting dermatoses and malignancies (e.g., acne vulgaris, atopic dermatitis, and melanoma); infectious diseases (e.g., human papillomavirus (HPV); varicella zoster virus (VZV); herpes zoster (HZ); warts; smallpox; mpox (monkeypox); hand, foot, and mouth disease (HFMD); candidiasis and Group B Streptococcus (GBS); and neglected tropical diseases (e.g., Buruli ulcer, leprosy, and leishmaniasis). Through this review, we aim to provide a detailed understanding of the role of vaccines in dermatology, identify knowledge gaps, and propose areas for future research.

Effects of Light and Laser Therapies on the Microecosystem of Sebaceous Glands in Acne Treatment

BACKGROUND

Acne vulgaris (acne) is one of the most common skin diseases with complex pathogenesis. Numerous studies have shown that the microecosystem of sebaceous glands and Cutibacterium acnes play key roles in its pathogenesis. Antibiotics targeting C. acnes have been widely used in acne treatment, but the growing prevalence of antibiotic resistance has become alarming. Further research into the microecosystem of sebaceous glands and the role of specific C. acnes phylotypes in acne pathogenesis has led to a paradigm shift in acne treatment. Currently, non-antibiotic therapies such as light therapy and laser therapy are becoming increasingly popular, opening up new opportunities in acne management.

METHODS

Studies on the microecosystem of sebaceous glands associated with acne and the effects of light and laser therapies on the microecosystem in acne treatment were retrieved from the PubMed database.

RESULTS

Dysbiosis of the microecosystem of the pilosebaceous unit is closely related to the pathogenesis of acne. Light and laser therapies have an impact on the microecosystem of the pilosebaceous unit in acne treatment.

CONCLUSIONS

Light and laser therapies are the popular alternative options in acne treatment. The mechanisms of their effect on the microecosystem of sebaceous glands are not completely clear and require further research, especially for laser therapy.

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.

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.

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.

Vitis vinifera L. Leaf Extract, a Microbiota Green Ally against Infectious and Inflammatory Skin and Scalp Diseases: An In-Depth Update

The skin microbiota, with its millions of bacteria, fungi, and viruses, plays a key role in balancing the health of the skin and scalp. Its continuous exposure to potentially harmful stressors can lead to abnormalities such as local dysbiosis, altered barrier function, pathobiont overabundance, and infections often sustained by multidrug-resistant bacteria. These factors contribute to skin impairment, deregulation of immune response, and chronic inflammation, with local and systemic consequences. In this scenario, according to the needs of the bio-circular-green economy model, novel harmless strategies, both for regulating the diverse epidermal infectious and inflammatory processes and for preserving or restoring the host skin eubiosis and barrier selectivity, are requested. Vitis vinifera L. leaves and their derived extracts are rich in plant secondary metabolites, such as polyphenols, with antioxidant, anti-inflammatory, antimicrobial, and immunomodulatory properties that can be further exploited through microbe-driven fermentation processes. On this premise, this literature review aims to provide an informative summary of the most updated evidence on their interactions with skin commensals and pathogens and on their ability to manage inflammatory conditions and restore microbial biodiversity. The emerging research showcases the potential novel beneficial ingredients for addressing various skincare concerns and advancing the cosmeceutics field as well.

Research progress on the role of macrophages in acne and regulation by natural plant products

Acne vulgaris is one of the most common skin diseases. The current understanding of acne primarily revolves around inflammatory responses, sebum metabolism disorders, aberrant hormone and receptor expression, colonization by Cutibacterium acnes, and abnormal keratinization of follicular sebaceous glands. Although the precise mechanism of action remains incompletely understood, it is plausible that macrophages exert an influence on these pathological features. Macrophages, as a constituent of the human innate immune system, typically manifest distinct phenotypes across various diseases. It has been observed that the polarization of macrophages toward the M1 phenotype plays a pivotal role in the pathogenesis of acne. In recent years, extensive research on acne has revealed an increasing number of natural remedies exhibiting therapeutic efficacy through the modulation of macrophage polarization. This review investigates the role of cutaneous macrophages, elucidates their potential significance in the pathogenesis of acne, a prevalent chronic inflammatory skin disorder, and explores the therapeutic mechanisms of natural plant products targeting macrophages. Despite these insights, the precise role of macrophages in the pathogenesis of acne remains poorly elucidated. Subsequent investigations in this domain will further illuminate the pathogenesis of acne and potentially offer guidance for identifying novel therapeutic targets for this condition.

Peiminine Exerts Its Anti-Acne Effects by Regulating the NF-κB Pathway

Peiminine is the main natural alkaloid compound extracted from the Chinese herb Fritillaria. Although peiminine is known for its antioxidant and anti-inflammatory effects in conditions such as mastitis and arthritis, its impact on inflammation induced by Cutibacterisum acnes (C. acnes) has not been explored. The aim of this study was to investigate the effect of peiminine on C. acnes-induced inflammatory responses in the skin and to identify the underlying mechanism involved. We discovered that peiminine inhibits the C. acnes-induced expression of inflammatory mediators such as pro-interleukin-1β (pro-IL-1β), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in mouse bone marrow-derived macrophages (BMDMs). Peiminine suppressed the activation of nuclear factor-kappa B (NF-κB) without affecting the activation of mitogen-activated protein kinase (MAPK) pathways such as JNK, ERK, and p38 MAPK. In addition, we found that peiminine suppressed inflammatory cytokine expression and ameliorated histological symptoms in C. acnes-induced mouse skin. Our study is the first to provide evidence that peiminine has an inhibitory effect on acne, and it points toward the potential of incorporating peiminine into cosmetic and pharmaceutical formulations for acne treatment.