What does acne genetics teach us about disease pathogenesis?

Integrative bioinformatics and experimental validation of hub genetic markers in acne vulgaris: Toward personalized diagnostic and therapeutic strategies

BACKGROUND

Acne vulgaris is a widespread chronic inflammatory dermatological condition. The precise molecular and genetic mechanisms of its pathogenesis remain incompletely understood. This research synthesizes existing databases, targeting a comprehensive exploration of core genetic markers.

METHODS

Gene expression datasets (GSE6475, GSE108110, and GSE53795) were retrieved from the GEO. Differentially expressed genes (DEGs) were identified using the limma package. Enrichment analyses were conducted using GSVA for pathway assessment and clusterProfiler for GO and KEGG analyses. PPI networks and immune cell infiltration were analyzed using the STRING database and ssGSEA, respectively. We investigated the correlation between hub gene biomarkers and immune cell infiltration using Spearman's rank analysis. ROC curve analysis validated the hub genes' diagnostic accuracy. miRNet, TarBase v8.0, and ChEA3 identified miRNA/transcription factor-gene interactions, while DrugBank delineated drug-gene interactions. Experiments utilized HaCaT cells stimulated with Propionibacterium acnes, treated with retinoic acid and methotrexate, and evaluated using RT-qPCR, ELISA, western blot, lentiviral transduction, CCK-8, wound-healing, and transwell assays.

RESULTS

There were 104 genes with consistent differences across the three datasets of paired acne and normal skin. Functional analyses emphasized the significant enrichment of these DEGs in immune-related pathways. PPI network analysis pinpointed hub genes PTPRC, CXCL8, ITGB2, and MMP9 as central players in acne pathogenesis. Elevated levels of specific immune cell infiltration in acne lesions corroborated the inflammatory nature of the disease. ROC curve analysis identified the acne diagnostic potential of four hub genes. Key miRNAs, particularly hsa-mir-124-3p, and central transcription factors like TFEC were noted as significant regulators. In vitro validation using HaCaT cells confirmed the upregulation of hub genes following Propionibacterium acnes exposure, while CXCL8 knockdown reduced pro-inflammatory cytokines, cell proliferation, and migration. DrugBank insights led to the exploration of retinoic acid and methotrexate, both of which mitigated gene expression upsurge and inflammatory mediator secretion.

CONCLUSION

This comprehensive study elucidated pivotal genes associated with acne pathogenesis, notably PTPRC, CXCL8, ITGB2, and MMP9. The findings underscore potential biomarkers, therapeutic targets, and the therapeutic potential of agents like retinoic acid and methotrexate. The congruence between bioinformatics and experimental validations suggests promising avenues for personalized acne treatments.

Prevalence of acne and its impact on quality of life and practices regarding self-treatment among medical students

Acne vulgaris is one of the most common skin diseases worldwide and causes great distress to patients. In addition, most acne patients suffer from low self-esteem and social withdrawal. This study aimed to assess the prevalence of acne and its impact on quality of life among medical students. It also evaluates the patterns of self-treatment use. The study population consisted of all medical students from An-Najah National University (ANU) and the hospital. The questionnaire consists of three parts, and the first part consists of questions regarding demographic information. The second part consisted of questions to measure the severity of acne using the acne severity scale as well as the Cardiff Disability Index, which assesses the quality of life concerning acne in medical students. Finally, the third part consisted of questions exploring and assessing acne self-treatment. The mean age of our study sample was 21.3 ± 1.9 years, with a female predominance of 72.3%. The prevalence of acne among medical students was 80.9%, and 36.6% practiced self-medication. Acne was strongly associated with female sex (p < 0.001) and skin type (p = 0.024). Regarding diet, dairy consumption (p = 0.007), sweets (p < 0.001), chocolate (p < 0.001), and oily food (p = 0.006) were all significantly associated with acne. Skin type was strongly associated with the severity of acne (p < 0.001) and the Cardiff acne disability index (p = 0.016). Gender (p = 0.039) was also associated with Cardiff acne disability. A significant correlation was found between the severity of acne and impaired quality of life. The most commonly used topical agent for self-treatment remedies was antibiotics (70.3%). The most commonly used oral agent was isotretinoin (9.4%). A total of 22.7% of the students used herbal products, while 47.7% used home remedies. Acne is prevalent among medical students, with a high percentage of students having different degrees of impairment in their daily lives. As a result, self-medication among acne sufferers is highly common. Awareness of the appropriate use of self-medication should increase among medical students.

1927nm fractional thulium fiber laser combined with 30% salicylic acid for the treatment of acne and acne scars: A prospective, randomized, and split-face study

OBJECTIVES

Patients with acne usually develops acne scars subsequently, early intervention of scars is crucial in acne management. 1927nm fractional thulium fiber laser (TFL) is effective in scars improvement and chemical peels with 30% supramolecular salicylic acid (SSA) can be applied for the treatment of acne. The purpose of this study is to evaluate and compare the efficacy and safety of TFL monotherapy versus the concomitant application of TFL and 30% SSA on acne and acne scars.

MATERIALS AND METHODS

Thirty-three patients with acne and acne scars were enrolled, and two sides of the face were randomly divided to receive either TFL and SSA chemical peeling or TFL. Four sessions of TFL treatments were applied with 4-week intervals for both sides, SSA combined treatment side received eight SSA chemical peels with 2-week intervals additionally. GAGS, ECCA score, the number of acne lesions, melanin index (MI) and erythema index (EI), transepidermal water loss (TEWL), and side effects were recorded at Weeks 0, 4, 8, 12, and 18. Satisfaction of patients was recorded on both sides at the end of the study.

RESULTS

Thirty patients completed the study. Both control group (TFL monotherapy) and SSA group (TFL combined with SSA chemical peeling) significantly improved GAGS and ECCA score. SSA group showed higher efficacy in terms of GAGS and ECCA score, acne lesion count, TEWL, MI, EI, and satisfaction than control group. All the side effects were temporary and tolerable, no adverse effects were observed.

CONCLUSIONS

Both TFL and the TFL combined with 30% SSA chemical peeling are safe and effective for the treatment and prevention of acne and acne scars, though the combined group has higher efficacy.

Insulin and the sebaceous gland function

Insulin affects metabolic processes in different organs, including the skin. The sebaceous gland (SG) is an important appendage in the skin, which responds to insulin-mediated signals, either directly or through the insulin growth factor 1 (IGF-1) axis. Insulin cues are differently translated into the activation of metabolic processes depending on several factors, including glucose levels, receptor sensitivity, and sebocyte differentiation. The effects of diet on both the physiological function and pathological conditions of the SG have been linked to pathways activated by insulin and IGF-1. Experimental evidence and theoretical speculations support the association of insulin resistance with acne vulgaris, which is a major disorder of the SG. In this review, we examined the effects of insulin on the SG function and their implications in the pathogenesis of acne.

Prevalence and risk factors of acne scars in patients with acne vulgaris

BACKGROUND

Acne scar is a persistent complication of acne vulgaris. However, the prevalence and risk factors are still unclear. This study aimed to assess the global prevalence and risk factors of acne scars in patients with acne.

MATERIALS AND METHODS

A systematic search of published studies in three databases was performed and the meta-analyses were conducted.

RESULTS

Finally, we included 37 studies involving 24 649 acne patients. And, the pooled prevalence of acne scars in these patients was 47% (95% confidence interval [CI]: 38-56%). Besides, the differences in prevalence were observed based on the subgroup analysis for age, gender, acne severity, source of patients, and so on. Subsequently, we quantified the relationship of three risk factors with acne scars: male gender (odds ratio [OR]: 1.58, 95% CI: 1.19-2.09), positive family history of acne (OR: 2.73, 95% CI: 1.26-5.91), and acne severity (OR for moderate acne: 2.34, 95% CI: 1.54-3.57; OR for severe acne: 5.51, 95% CI: 2.45-12.41).

CONCLUSION

Herein, we found that 47% of acne patients suffered from acne scars and identified three risk factors: male gender, positive family history of acne, and acne severity. In order to reduce acne scarring, attention and effective therapy early in the course of acne is important.

Genome-wide meta-analysis identifies novel loci conferring risk of acne vulgaris

Acne vulgaris is a common chronic skin disorder presenting with comedones, cystic structures forming within the distal hair follicle, and in most cases additionally with inflammatory skin lesions on the face and upper torso. We performed a genome-wide association study and meta-analysis of data from 34,422 individuals with acne and 364,991 controls from three independent European-ancestry cohorts. We replicated 19 previously implicated genome-wide significant risk loci and identified four novel loci [11q12.2 (FADS2), 12q21.1 (LGR5), 17q25.3 (FASN), and 22q12.1 (ZNRF3-KREMEN1)], bringing the total number of reported acne risk loci to 50. Our meta-analysis results explain 9.4% of the phenotypic variance of acne. A polygenic model of acne risk variants showed that individuals in the top 5% of the risk percentiles had a 1.62-fold (95% CI 1.47-1.78) increased acne risk relative to individuals with average risk (20-80% on the polygenic risk score distribution). Our findings highlight the Wnt and MAPK pathways as key factors in the genetic predisposition to acne vulgaris, together with the effects of genetic variation on the structure and maintenance of the hair follicle and pilosebaceous unit. Two novel loci, 11q12.2 and 17q25.3, contain genes encoding key enzymes involved in lipid biosynthesis pathways.

Acne Vulgaris Relapse in Sudanese Patients Treated with Oral Isotretinoin: Rate and Predictive Factors

Purpose

Acne vulgaris is a skin disorder primarily affecting teenagers and young adults. Acne relapse is the main drawback of oral isotretinoin (OI), which is the golden therapy for severe acne. This study aimed to assess the rate and predictive factors of acne relapse among Sudanese patients using OI.

Patients and Methods

A cross-sectional study was conducted in a dermatology and venereology clinic-Sudan, using a self-administered questionnaire and data collection sheet. Patients using OI for acne treatment were enrolled in the study. Chi-square test and logistic regression analysis were used to evaluate the association between variables. P-value <0.05 was considered statistically significant.

Results

225 acne patients (mean age: 26.0±4.2 years, females: 88.9%) were included in this study. OI daily dose ranged from 0.25 to 1 mg/kg/day, with frequent daily doses of 40-49 mg (57.3%) over 3-6 months (81.8%). Around one-third of patients (36%) received maintenance therapy after completion of OI course. At a 2-year follow-up, approximately 36% of patients experienced acne relapse that commonly occurred within 6-18 months after the last OI therapy. Early discontinuation of OI was a positive predictor of acne relapse which was 3.99 times greater in patients who had early discontinued OI than those completing the planned OI course (OR=3.99; p=0.002). OI cumulative doses of 120-139 mg/kg and 140-159 mg/kg were negative predictors of acne relapse (OR=0.23; p=0.001 and OR=0.15; p=0.02, respectively). Most patients (94.2%) received prescription OI, and 76.4% of women were advised to use contraceptives. About 69% of patients practiced skin care.

Conclusion

About one-third of patients experienced acne relapse. Early discontinuation and low cumulative doses of OI are the main risk factors for acne relapse. Long-term therapy of OI, with cumulative doses of 120-159 mg/kg, would be beneficial to reduce acne relapse.

Honokiol Improves Acne-like Lesions in a Rabbit Ear Model by Alleviating Hyperkeratosis and Sebum Secretion

The prevalence of acne vulgaris is high, but the topical retinoids used as the foundation of treatment have teratogenic and photosensitivity properties. Previous studies have suggested that honokiol, a small-molecule compound extracted from Magnolia officinalis, could effectively inhibit Cutibacterium acnes ( C acnes) and inflammation in vitro. However, the effect in vivo is unclear. The rabbit ear acne model that we created showed obvious comedones and hyperkeratosis. These lesions were repeatedly measured and recorded by dermatoscopy (ultraviolet light). Compared with the control group, topical 2.5% honokiol cream obviously improved the comedones and hyperkeratosis and effectively reduced sebum secretion, as shown by Oil Red O staining. The effects were equivalent to those of adapalene gel without local side effects. We added honokiol's other functions to acne treatment in addition to antiinflammation, but further studies are needed.

Untargeted metabolomics analysis of the plasma metabolic signature of moderate-to-severe acne

BACKGROUND

Acne vulgaris is a chronic inflammatory disease of pilosebaceous units and sebaceous glands. This study aimed to find out metabolites and metabolite pathways abnormal in moderate-to-severe acne vulgaris patients.

METHODS

The plasma metabolites LC-MS/MS analysis was conducted on 30 moderate-to-severe acne patients and 32 healthy controls. Multivariate data analyses were applied to identify the distinguishing metabolites.

RESULTS

Totally, 63 significant differential metabolites and 40 metabolic pathways were significantly changed. The top 3 metabolites on the basis of their VIP scores obtained from the PLS-DA were 2-Oxoadipic acid, Myo-inositol and Citrate. In addition, four sphingolipid metabolites include sphinganine, sphingosine, O-Phosphoethanolamine, and sphingomyelin (d18:1/18:0) were identified. The most closely related metabolic pathways included ATP-binding cassette (ABC) transporters and sphingolipid signaling pathway in moderate-to-severe acne patients.

CONCLUSIONS

The observed difference in metabolic profiles between acne patients and healthy controls provides a new insight into the link between plasma metabolic changes and acne vulgaris.

TRASS: a global approach to assess the severity of truncal acne

INTRODUCTION

Only a small amount of published data regarding truncal acne is available and no proper tool to assess its severity exists.

AIM

to provide dermatologists with an easy-to-use tool to assess truncal acne (TRASS, truncal acne severity scale) using a global approach.

METHODS

A scoring tool that assesses the severity of acne (based on GEA and ECLA scales) on the trunk using a global approach was built, including three subscores: family history, clinical signs and quality of life (QoL). In order to test TRASS, the experts used photos of 47 patients attending their clinics with truncal acne. The ROP (Regression OPtimized) model was applied to assess the diagnosis performance of TRASS and to identify items contributing to the classification of the patients. Internal testing was made to demonstrate the robustness of the model. Correlation analyses between the different items were performed to evaluate the interaction between the different items and their impact on the severity grading of truncal acne.

RESULTS

Patients with the most severe acne were identified by TRASS. The error level was 6.6% after internal validation and 10.4% when using the median value or the centile 75^th (6.6% and 10.4%). Correlation was significant between systemic treatment and scars (p=0.0025) and nodules (p=0.01988) and between location and QoL (p=0.0095).

CONCLUSION

TRASS is the first global, patient-centred approach to evaluate truncal acne by scoring the importance of each factor independently from its clinical severity. TRASS may allow the practitioner to choose and validate the most suitable therapy together with the patient in order to treat his or her truncal acne successfully and to limit treatment failure.

Combined subcision, autologous platelet-rich plasma, and CROSS technique in the treatment of atrophic acne scars: Prospective split face study

Acne scars represent a therapeutic dilemma. This study aimed to evaluate the efficacy of combined subcision, autologous platelet-rich plasma (PRP), and chemical reconstruction of skin scars (CROSS) technique in the treatment of acne scars. In 20 patients with atrophic acne scars, one facial side was treated with subcision plus PRP, and the other was treated with the same combination plus CROSS technique (trichloroacetic acid 50%) for 3 sessions at 3-week intervals. Clinical evaluation, digital photography, quantitative global scarring grading system, and Lipper and Perez score were done at baseline, every session, and 1 month after the last session. Participants assessed their improvement at the end of the follow-up period using a scale (0 to 10). There was a significant reduction in quantitative global scarring grading system (P < .001) and Lipper and Perez score (P < .001) after treatment compared with baseline in both sides. No significant difference was found when the two treated sides were compared after treatment by both scores. Patients' satisfaction was excellent (12 patients [60%]) and good (eight patients [40%]) with no significant difference between both sides. In conclusion, combined subcision and PRP is recommended for acne scars. Adding CROSS technique (trichloroacetic acid 50%) did not further ameliorate the condition.

Environmental, inflammatory, and anti-inflammatory squad in acne vulgaris pathogenesis: AhR, IL-36, and IL-38

BACKGROUND

Acne vulgaris (AV) is an extraordinarily common skin condition. The high prevalence of AV is linked to the exposure factors, as environmental pollutants and climatic factors, occupational, psychosocial, and lifestyle factors. The AhR plays a critical part in environmental toxic action. The AhR expression and imbalance in the IL-36 & 38 expression may have a role in inflammation and AV pathogenesis.

AIMS

To detect possible links between environmental, inflammatory, and anti-inflammatory factors in AV pathogenesis through measuring AhR, IL-36, and IL-38 mRNA gene expression levels.

PATIENTS AND METHODS

Total of 100 subjects (70 AV patients and 30 apparently healthy control subjects) were tested for AhR, IL-36γ, and IL-38 mRNA levels by quantitative real-time PCR.

RESULTS

The median levels of AhR and IL-36 mRNA gene expression were considerably greater, while that of IL-38 was essentially lower in AV than healthy subjects (p < 0.001, 0.021 and 0.002, respectively). The AhR and IL-36 mRNA gene expression levels increased, while IL-38 decreased significantly with higher grades of severity (p < 0.001, 0.001, and <0.001, respectively). ROC curve showed that AhR mRNA gene expression level had the best AUC for diagnosis of AV, with better sensitivity and specificity than IL-36 and IL-38.

CONCLUSIONS

Higher levels of AhR, IL-36, and lower levels of IL-38 gene expression were significantly associated with AV patients and higher grades of severity. AhR had better diagnostic ability than IL-38 and IL-36.

Familial occurrence of follicular keratosis of the chin

Follicular keratosis of the chin is a rare and poorly understood pediatric disorder with a characteristic presentation of multiple follicular papules on the chin. Although prolonged friction or pressure over the chin is considered an etiology, such history is not present in most cases. It sometimes occurs within families without any evidence of physical trauma, suggesting a genetic predisposition of the patients to develop the disease. In the present study, we report two brothers with the disease, in whom no definite physical trauma was identified but comedo formation was evident. The clinical presentation of follicular keratosis of the chin is unique, particularly owing to its specific location on the chin with an age predilection from late childhood to puberty. We assume that the hormone status is an etiology of the disease since the chin is an area where androgenic hormones target at puberty and comedogenesis is a well-known biological function of the hormone. We also assumed that the susceptibility to the hormone may involve in the development of the familial follicular keratosis of the chin.

Alterations in mental health and quality of life in patients with skin disorders: a narrative review

The presence of lesions in visible areas of skin may cause emotional troubles in patients, including low self-worth, embarrassment, sorrow, and social isolation. Those alterations may predispose to psychiatric disorders such as anxiety, depression, and even suicidal ideation, severely affecting patients' health state and quality of life (QoL). In this article, we focus on dermatologic patients that present with secondary mental health alterations. Thus, we offer a detailed description of mental disorders observed in patients with acne vulgaris, atopic dermatitis, psoriasis, ichthyosis, vitiligo, and hidradenitis suppurativa. Moreover, we point out the relationship between the severity of the cutaneous symptoms with mental illnesses and QoL decline. Our objective was to highlight the importance of mental health care for patients with skin diseases. The impact of skin alterations on the mental health of dermatological patients should be a central concern. Likewise, the timely identification and treatment of mental disorders are essential for the comprehensive management of these skin diseases.

Cutibacterium acnes: Much ado about maybe nothing much

Cutibacterium acnes (also known as Propionibacterium acnes) has long been implicated in the pathogenesis of acne, inspiring both therapeutic and personal care approaches aiming to control the disease by controlling the bacterium. The purported association has made people with acne feel dirty and led to the-at times excessive-use of cleansers, antiseptics and antibiotics for the condition. However, recent evidence seems to weaken the case for C. acnes' involvement. New genetics and molecular biology findings strongly suggest that abnormal differentiation of sebaceous progenitor cells causes comedones, the primary lesions in acne. Comodegenesis is initiated by androgens and is unlikely to be triggered by C. acnes, which probably doesn't affect sebaceous differentiation. Is there still a place for it in this understanding of acne? It is necessary to critically address this question because it has consequences for treatment. Antibiotic use for acne noticeably contributes to microbial drug resistance, which we can ill afford. In this Viewpoint, we explore if and how C. acnes (still) fits into the developing view on acne. We also briefly discuss the implications for therapy in the light of antibiotic resistance and the need for more targeted therapies.

Gene variants associated with acne vulgaris presentation and severity: a systematic review and meta-analysis

BACKGROUND

Multiple factors have been attributed to acne vulgaris predisposition and individual variations in the severity of skin symptoms, and genetics stood out as one of the major factors.

METHODS

We performed a systematic review on the genes and their variants that have been investigated for association with acne presentation and severity. A random-effect meta-analysis using the allele model (minor allele vs. major allele) was also conducted to provide an overall estimation of risk effects of frequently reported gene variants. This included a subset data of 982 acne cases and 846 controls extracted from our existing GWAS database on various allergic and skin diseases among Singapore Chinese.

RESULTS

Systematic review of 51 articles covering Asians and Caucasians found 60 genes/loci and their 100 variants implicated in acne; majority of them were in the intron, coding region/missense, and promoter regions. The commonly studied candidate genes/gene families include tumor necrosis factor (TNF), and the interleukin (IL) and cytochrome P450 (CYP) gene families. Our meta-analysis showed that most of the analyzed gene variants exhibited insignificant pooled odds ratio (pOR) and significant heterogeneity between studies. Nevertheless, we found that TNF rs1800629 A allele carriers and CYP17A1 rs743572 T allele carriers had significantly reduced mild acne risk [pOR: 0.60; 95% Confidence Interval (CI): 0.33-0.86] and severe acne risk (pOR: 0.59; 95% CI: 0.40-0.79), respectively, across populations. Overall, FST (follistatin) rs629725 A allele poses a significantly modest increased risk for acne presentation (pOR: 1.19, 95% CI: 1.14, 1.23), but neither TIMP2 (TIMP metallopeptidase inhibitor 2) rs8179090 nor CYP1A1 rs4646903 (pOR: 0.96, 95% CI: 0.80-1.12; pOR: 0.95, 95% CI: 0.83, 1.08), respectively. We discovered 15 novel SNPs in the 3' UTR region of the Toll-like Receptor 4 gene (TLR4) associated with acne presentation.

CONCLUSIONS

This systematic review and meta-analysis suggest that genes influencing inflammatory responses, specifically TNF, and genes influencing the function and activity of sebaceous glands, specifically CYP17A1 and FST, have potential risk variants for acne presentation and severity across populations. Understanding the genetic susceptibility factors and biological pathways involved in the pathogenesis of acne will help us to gain insights into developing effective acne treatments.

Modifiable and non-modifiable epidemiological risk factors for acne, acne severity and acne scarring among Malaysian Chinese: a cross-sectional study

Background

Acne vulgaris, a highly prevalent multifactorial inflammatory skin disease, can be categorised into different severity and scarring grades based on the type, number, and severity of lesions. While many epidemiology studies have investigated the risk factors for acne presentation, fewer studies have specifically studied the risk factors for acne severity and scarring. Therefore, this study investigated the prevalence of acne, acne severity and scarring grades, and their associated non-modifiable and modifiable epidemiological risk factors among Malaysian Chinese.

Methods

A total of 1840 subjects (1117 cases/723 controls) completed an investigator-administered questionnaire as part of a cross-sectional study, which include socio-demographics, familial history, lifestyle factors, dietary habits, and acne history. Acne cases were further evaluated for their severity (n = 1051) and scarring (n = 1052) grades by a trained personnel.

Results

Majority of the acne cases (up to 69%) had mild acne or Grade 1/2 scarring, while 21.6% had moderate/severe acne and 5.5% had Grade 3/4 scarring. Males had significantly higher risk of presenting with higher grades of acne scarring. Those who had acne, regardless of severity and scarring grades, had strong positive familial history (either in parents and/or sibling). Frequent consumption (most or all days) of foods that are commonly consumed during breakfast (butter, probiotic drinks, cereals and milk) decreased the risk for acne presentation and higher acne scarring, while periodic consumption (once/twice per week) of nuts and burgers/fast food decreased the risk for higher acne severity. Alcohol drinking was significantly associated with increased risk for acne presentation, while paternal, parental and household smoking were associated with reduced risk of more severe acne.

Conclusions

In conclusion, positive familial history is a strong predisposing factor in influencing acne presentation, severity and scarring. Frequent consumption of foods that are commonly consumed during breakfast is protective against acne presentation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10681-4.

Cutaneous Malassezia: Commensal, Pathogen, or Protector?

The skin microbial community is a multifunctional ecosystem aiding prevention of infections from transient pathogens, maintenance of host immune homeostasis, and skin health. A better understanding of the complex milieu of microbe-microbe and host-microbe interactions will be required to define the ecosystem's optimal function and enable rational design of microbiome targeted interventions. Malassezia, a fungal genus currently comprising 18 species and numerous functionally distinct strains, are lipid-dependent basidiomycetous yeasts and integral components of the skin microbiome. The high proportion of Malassezia in the skin microbiome makes understanding their role in healthy and diseased skin crucial to development of functional skin health knowledge and understanding of normal, healthy skin homeostasis. Over the last decade, new tools for Malassezia culture, detection, and genetic manipulation have revealed not only the ubiquity of Malassezia on skin but new pathogenic roles in seborrheic dermatitis, psoriasis, Crohn's disease, and pancreatic ductal carcinoma. Application of these tools continues to peel back the layers of Malassezia/skin interactions, including clear examples of pathogenicity, commensalism, and potential protective or beneficial activities creating mutualism. Our increased understanding of host- and microbe-specific interactions should lead to identification of key factors that maintain skin in a state of healthy mutualism or, in turn, initiate pathogenic changes. These approaches are leading toward development of new therapeutic targets and treatment options. This review discusses recent developments that have expanded our understanding of Malassezia's role in the skin microbiome, with a focus on its multiple roles in health and disease as commensal, pathogen, and protector.

Antibiotic Resistance in Acne: Mechanisms, Complications and Management

Antibiotic resistance in acne was first observed in the 1970s, and since the 1980s has become a major concern in dermatologic daily practice. The mechanisms for this type of resistance include biofilm formation that promotes virulence and the transmission of resistant bacterial strains. Genetic mutations with modification of ribosomal RNA, alteration in efflux pumps, and enzymatic inactivation are able to create resistance to tetracyclines and macrolides. The state of art in acne treatment is no longer to use antimicrobials as monotherapy. There should be a time limit for its use plus the employment of non-antibiotic maintenance. Earlier initiation of oral isotretinoin therapy should be considered in patients with insufficient response to antimicrobials, severe acne, or a history of repeated antimicrobial use. A better understanding of acne pathogenesis, the subtypes of Propionibacterium (also known as Cutibacterium) acnes, homeostasis of the skin microbiota, and the mechanisms of antibiotic resistance would be useful in the selection of narrow-spectrum or species-specific antimicrobials, as well as the non-antimicrobial, anti-inflammatory treatment of acne. A number of novel treatments awaiting clinical proof may include the use of bacteriophages, natural or synthetic antimicrobial peptides, probiotics, and biofilm-targeting agents, as well as the reassessment of phototherapy.

Acne in the first three decades of life: An update of a disorder with profound implications for all decades of life

Acne vulgaris is a chronic, inflammatory, skin condition that involves the pilosebaceous follicles and is influenced by a variety of factors including genetics, androgen-stimulation of sebaceous glands with abnormal keratinization, colonization with Cutibacterium acnes (previously called Propionibacterium acnes), and pathological immune response to inflammation. Acne can occur at all ages and this discussion focuses on the first three decades of life. Conditions that are part of the differential diagnosis and/or are co-morbid with acne vulgaris are also considered. Acne in the first year of life includes neonatal acne (acne neonatorum) that presents in the first four weeks of life and infantile acne that usually presents between 3 and 6 months of the first year of life with a range of 3 to 16 months after birth. Acne rosacea is a chronic, inflammatory, skin condition that is distinct from acne vulgaris, typically presents in adults, and has four main types: erythemato-telangiectatic, papulopustular, phymatous and ocular. Treatment options for acne vulgaris include topical retinoids, topical benzoyl peroxide, antibiotics (topical, oral), oral contraceptive pills, isotretinoin, and others. Management must consider the increasing impact of antibiotic resistance in the 21st century. Psychological impact of acne can be quite severe and treatment of acne includes awareness of the potential emotional toll this disease may bring to the person with acne as well as assiduous attention to known side effects of various anti-acne medications (topical and systemic). Efforts should be directed at preventing acne-caused scars and depigmentation on the skin as well as emotional scars within the person suffering from acne.

Orobol, A Derivative of Genistein, Inhibits Heat-Killed Propionibacterium acnes-Induced Inflammation in HaCaT Keratinocytes

Acne is a chronic skin disease that typically occurs in the teens and twenties, and its symptoms vary according to age, sex, diet, and lifestyle. The condition is characterized by hyperproliferation of keratinocytes in the epidermis, sebum overproduction, excessive growth of Propionibacterium acnes, and P. acnes-induced skin inflammation. Interleukin (IL)-1α and IL-6 are predominant in the inflammatory lesions of acne vulgaris. These cytokines induce an inflammatory reaction in the skin in the presence of pathogens or stresses. Moreover, IL-1α accelerates the production of keratin 16, which is typically expressed in wounded or aberrant skin, leading to abnormalities in architecture and hyperkeratinization. Orobol (3',4',5,7-tetrahydroxyisoflavone) is a metabolite of genistein that inhibited the P. acnes-induced increases in IL-6 and IL-1α levels in human keratinocytes (HaCaTs) more effectively compared with salicylic acid. In addition, orobol decreased the IL-1α and IL-6 mRNA levels and inhibited the phosphorylation of inhibitor of kappa-B kinase, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha, and mitogen-activated protein kinase induced by P. acnes. Finally, the expression of Ki67 was decreased by orobol. Thus, orobol ameliorated the inflammation and hyperkeratinization induced by heat-killed P. acnes and thus has potential for use in functional foods and cosmetics.

The KEAP1/NRF2 Signaling Pathway in Keratinization

Keratinization is a tissue adaptation, but aberrant keratinization is associated with skin disorders such as ichthyoses, atopic dermatitis, psoriasis, and acne. The disease phenotype stems from the interaction between genes and the environment; therefore, an understanding of the adaptation machinery may lead to a new appreciation of pathomechanisms. The KEAP1/NRF2 signaling pathway mediates the environmental responses of squamous epithelial tissue. The unpredicted outcome of the Keap1-null mutation in mice allowed us to revisit the basic principle of the biological process of keratinization: sulfur metabolism establishes unparalleled cytoprotection in the body wall of terrestrial mammals. We summarize the recent understanding of the KEAP1/NRF2 signaling pathway, which is a thiol-based sensor-effector apparatus, with particular focuses on epidermal differentiation in the context of the gene-environment interaction, the structure/function principles involved in KEAP1/NRF2 signaling, lessons from mouse models, and their pathological implications. This synthesis may provide insights into keratinization, which provides physical insulation and constitutes an essential innate integumentary defense system.

Recent advances in understanding and managing acne

Multidisciplinary investigations into the pathogenesis of acne have significantly progressed over the past three years. Studies of the etiology of acne from the perspectives, for example, of sebaceous gland biology, sebum, genetics, keratinization, differentiation, hair cycles, immunology, bacteriology, and wound healing have elucidated its pathogenesis. This has led to the development of new therapies and paved the way for advanced studies that will enable the further evolution of acne treatment.