The skin has a multifactorial aging process, caused by both intrinsic and extrinsic factors. A major theory of aging involves cellular senescence or apoptosis resulting from oxidative damage as the skin’s antioxidant system tends to weaken with age. The human microbiota is a complex ecosystem that is made up of microorganisms (bacteria, fungi, and viruses). Both gut and skin microbiota have essential roles in the protection against invading pathogens, mediating inflammatory conditions, and the modulation of the immune system which is involved in both innate and adaptive immune responses. However, the human microbiome could be changed during the life stage and affected by various perturbations. An alteration of the intestinal bacteria results in “microbial dysbiosis” which is associated with the influence of various diseases, including aging. The skin interactome is a novel integration of the “genome-microbiome-exposome” that plays a significant role in skin aging and skin health. Mitigating the negative impacts of factors influencing the skin interactome should be the future strategy to protect, prevent, and delay skin aging along with preserving healthy skin conditions. This review summarizes the current evidence on how human microbiomes affect skin aging and demonstrates the possible interventions, relating to human microbiomes, to modulate skin health and aging. Probiotics-based products are currently available mainly for the add-on treatment of many dermatologic conditions. However, at this point, there are limited clinical studies on skin anti-aging purposes and more are required as this evolving concept is on the rise and might provide an insight into future therapeutic options.

Background: Melasma is a complex and multipathophysiological condition that is challenging to treat. The roles of each element in the dermis were highlighted in this recent year due to targeting it with emerging therapies. Although some studies have demonstrated abnormal findings in the dermis of melasma lesions, there are no integrated data regarding these findings. Purpose: This article aims to discuss each finding in the dermis of melasma lesions and to provide some ideas about treatment options. Methods: An Internet search was completed using the MEDLINE, Embase, Scopus, and Google Scholar databases for relevant literature through June 2021 and reference lists of respective articles. Only the articles published in English language were included. Results: Several studies have focused on the dermal changes in melasma. Common findings included basement membrane disruption, pendulous melanocytes, marked solar elastosis, increased melanophages, increased mast cells, and neovascularization. In addition, each of them had the specified mechanism that may relate with the others. Conclusion: Several changes in the dermis of melasma lesion may be connected with pathological changes in the epidermis. This may serve as a potential target treatment for melasma, which requires a multimodal approach.

Background: Trichophyton mentagrophytes species complex comprises dermatophytes responsible for common superficial fungal infections affecting keratinised tissues. Recent shifts in taxonomy and increasing antifungal resistance—necessitate an updated understanding of this fungal complex.Objective: This narrative review provides a comprehensive update on the taxonomy, host immune response and clinical genotyping of the T. mentagrophytes complex, with a focus on zoonotic and anthropophilic infections in humans.Methods: A comprehensive literature search was conducted across PubMed and Scopus using MeSH terms and relevant keywords related to T. mentagrophytes, T. interdigitale, and T. indotineae. Eligible English‐language publications up to March 2025—including original research, case reports, reviews and guidelines—were included.Results: The T. mentagrophytes complex includes several genotypes with distinct transmission profiles. Genotypes III/III* are primarily zoonotic; genotype VII is sexually transmitted, especially in MSM populations; genotype VIII (T. indotineae) is anthropophilic and associated with terbinafine resistance. Infection involves keratinocyte adhesion, enzymatic skin barrier degradation and activation of pro‐inflammatory cytokines and antimicrobial peptides. Both innate and adaptive immunity, particularly Th1 and Th17 responses, are critical for fungal clearance, whereas chronic infections are associated with impaired T‐cell function and skewed Th2 responses.Conclusion: Emerging genotypes and drug resistance within the T. mentagrophytes complex pose increasing clinical challenges. Awareness of transmission patterns, immune evasion mechanisms and resistance profiles is essential for accurate diagnosis and effective management of dermatophytosis.

Purpose: This study aimed to demonstrate the effects of gender-affirming hormone therapy (GAHT) and gender-affirming procedures on the skin in transgender individuals. Methods: We conducted a cross-sectional study among transgender people. Skin conditions related to GAHT were assessed, including acne (using the Investigator's Global Assessment, IGA), postacne sequelae, melasma, hypertrichosis in androgen-sensitive areas (HAAs) in transgender men (TM) and hirsutism in transgender women (TW) (using the modified Ferriman–Gallwey score, mFG score), and hair loss (using the Hamilton–Norwood and Ludwig scale) at baseline, 6 months after GAHT, and the day on which the questionnaire was completed. Dermatological problems after gender-affirming procedures were evaluated. Results: A total of 159 patients, including 134 TM and 25 TW, were eligible to participate. The median duration of GAHT was 23 and 36 months in TM and TW, respectively. In TM, the median IGA score of facial acne increased from 1 at baseline to 3 after 6 months and decreased to 2 after 2 years of GAHT. The mFG score indicated HAA in all TMs after testosterone treatment. A total of 88.1% of TM had no hair loss before hormone therapy. However, after 2 years of GAHT, 76.1% of TM developed male pattern hair loss (MPHL), and 26.1% of them had moderate-to-severe MPHL. In TW, the median IGA and mFG scores decreased after 3 years of hormone therapy, and the proportion of female pattern hair loss (FPHL) in TW increased to 16% after GAHT. In both groups, the most common skin complication after gender-affirming surgery was hypertrophic scarring. Conclusions: GAHT in TM resulted in acne and MPHL, whereas GAHT in TW caused melasma and FPHL.

Background: Botulinum toxin A (BoNT‐A) is widely utilized in the management of hypertrophic and keloid scars. One proposed mechanism for scar prevention involves the inhibition of fibroblast migration in scars by BoNT‐A. However, the data regarding the effect of BoNT‐A on the migration of normal human dermal fibroblasts (NHDF) is limited.Objectives: The aim of this study was to investigate the inhibitory effect of different types and dilutions of BoNT‐A on the migration of NHDF.Methods: In vitro scratch wound assay, NHDF cells were cultured, incubated, and subjected to scratching using a sterile tip. Subsequently, the scratched NHDF monolayer was treated with different types of BoNT‐A, including onabotulinumtoxinA (ONA), incobotulinumtoxinA (INCO), prabotulinumtoxinA (PRABO), or letibotulinumtoxinA (LETI), at varying concentrations of 10, 20, 25, 40, 50, and 100 units/milliliter (U/mL). Additionally, abobotulinumtoxinA (ABO) was administered at concentrations of 33, 50, 66, 71, 100, 150, 300, and 500 U/mL. Normal saline solution (NSS) served as a negative control. The extent of NHDF migration was evaluated by comparing each dilution of BoNT‐A with the controls using high‐content imaging at the 48‐h time point. Furthermore, the viability of the of NHDF was assessed.Results: The concentrations of 25, 40, and 50 U/mL of ONA (p < 0.001) and 25 U/mL of LETI (p < 0.05) demonstrated significantly inhibited NHDF migration in comparison to the control group. Conversely, all dilutions of PRABO, INCO, and ABO exhibited comparable NHDF migration to that of the control group. Regarding NHDF viability, no significant decrease was observed across any of the BoNT‐A types and dilutions.Conclusion: Different types and dilutions of BoNT‐A demonstrated variable inhibitory effects on NHDF migration in vitro. The selection of BoNT‐A formulation may significantly impact the clinical outcome of scar prevention related to fibroblast migration.