Acne is an inflammatory disease and alterations of sebum composition initiate acne lesions

The cutaneous effects of androgens and androgen-mediated sebum production and their pathophysiologic and therapeutic importance in acne vulgaris

Background: The recognition of an association between the development of acne vulgaris (AV) and pubertal hormonal changes during adolescence dates back almost 100 years. Since these formative observations, a significant role of circulating hormones in the pathophysiology of AV and other cutaneous disorders has been established.Aims: This review article aims to provide an overview of clinical and preclinical evidence supporting the influences of androgens on the skin and their therapeutic importance in AV pathophysiology.Results: The cutaneous effects of hormones are attributable, to a large extent, to the influence of steroid hormones, particularly androgens, on sebocyte development and sebum production in both sexes. Androgen-mediated excess sebum production is implicated as a necessary early step in AV pathophysiology and is therefore considered an important therapeutic target in AV treatment. Although the local production and/or activity of androgens within the skin is believed to be important in AV pathophysiology, it has received limited therapeutic attention.Conclusions: We have summarized the current evidence in support of the therapeutic benefits of targeted hormonal treatment to decrease androgen-stimulated sebum production for the effective and safe treatment of AV in both male and female patients.

Hair Follicle-Targeted Delivery of Azelaic Acid Micro/Nanocrystals Promote the Treatment of Acne Vulgaris

Purpose

Acne vulgaris is a chronic inflammatory skin disorder centered on hair follicles, making hair follicle-targeted delivery of anti-acne drugs a promising option for acne treatment. However, current researches have only focused on the delivering to healthy hair follicles, which are intrinsically different from pathologically clogged hair follicles in acne vulgaris.

Patients and Methods

Azelaic acid (AZA) micro/nanocrystals with different particle sizes were prepared by wet media milling or high-pressure homogenization. An experiment on AZA micro/nanocrystals delivering to healthy hair follicles was carried out, with and without the use of physical enhancement techniques. More importantly, it innovatively designed an experiment, which could reveal the ability of AZA micro/nanocrystals to penetrate the constructed clogged hair follicles. The anti-inflammatory and antibacterial effects of AZA micro/nanocrystals were evaluated in vitro using a RAW264.7 cell model stimulated by lipopolysaccharide and a Cutibacterium acnes model. Finally, both the anti-acne effects and skin safety of AZA micro/nanocrystals and commercial products were compared in vivo.

Results

In comparison to commercial products, 200 nm and 500 nm AZA micro/nanocrystals exhibited an increased capacity to target hair follicles. In the combination group of AZA micro/nanocrystals and ultrasound, the ability to penetrate hair follicles was further remarkably enhanced (ER value up to 9.6). However, toward the clogged hair follicles, AZA micro/nanocrystals cannot easily penetrate into by themselves. Only with the help of 1% salicylic acid, AZA micro/nanocrystals had a great potential to penetrate clogged hair follicle. It was also shown that AZA micro/nanocrystals had anti-inflammatory and antibacterial effects by inhibiting pro-inflammatory factors and Cutibacterium acnes. Compared with commercial products, the combination of AZA micro/nanocrystals and ultrasound exhibited an obvious advantage in both skin safety and in vivo anti-acne therapeutic efficacy.

Conclusion

Hair follicle-targeted delivery of AZA micro/nanocrystals provided a satisfactory alternative in promoting the treatment of acne vulgaris.

Lipidomic analysis of facial skin surface lipids in acne in young women

BACKGROUND

Alterations in the secretion and composition of skin surface lipids (SSL) are closely associated with the development of acne. Lipidomics is a useful tool to analyse the SSL of different types of acne. Our previous study found that phosphatidylserine and triacylglycerols dominate SSL changes in male acne and infantile acne, respectively. However, skin surface lipids as well as specific lipids in female acne patients remain to be investigated.

OBJECTIVES

To analyse and compare the SSL profile of acne women and healthy women and to discuss the involvement of differential lipids in acne development.

METHODS

Systematic lipidomics approach (high-throughput UPLC-QTOF-MS technology in combination with multivariate data analysis methods) was used to analyse the variations of SSL between acne and healthy groups.

RESULTS

Analysis revealed significant differences in lipid content and composition between the two groups. Further analysis showed that levels of 13 individual lipids were significantly different and followed the same trend as the main class and subclasses. The largest individual contributor to the subgroup was triglycerides (TG) and phosphatidylinositol (PI). In addition, female acne patients exhibited reduced ceramide chain length (CCL) and increased levels of unsaturated fatty acids (UFAs), The changes of CCL in female acne are identical to male acne.

CONCLUSIONS

There was a significantly higher level of TG and PI in the SSL of female acne patients. A reduction in CCL and an increase in UFAs content might contribute to the reduced skin barrier function in acne patients. The results suggest that female acne may have different pathogenesis than male acne.

Mapping the evolution of acne research based on 100 top-cited articles: A bibliometric analysis of trends and hotspots from 2014 to 2023

BACKGROUND

Acne is a prevalent inflammatory condition of the pilosebaceous unit, which seriously affects the appearance and mental health of patients. Bibliometrics is the statistical analysis of academic literature in a certain field. We aimed to characterize the 100 most cited articles on acne from a bibliometric perspective, as well as explore the frontier hotspots and trends of acne.

METHODS

A search was conducted on the Web of Science database on August 8, 2023. we employed the terms "acne," "acne Vulgaris," and "common acne" in our search. The top 100 articles with the most citations throughout the time frame of 2014 to 2023 were discovered and assessed. The visualization study was carried out using bibliometric tools such as CiteSpace 6.2.R4, VOSviewer 1.6.18, and MapChart.

RESULTS

The top 100 most cited articles were published between 2014 and 2021, originated from a diverse range of 48 countries, with a predominant focus on the United States of America (USA) and Germany. The top 100 papers were cited between 50 and 712 times. Dreno B, from Nantes University, was the most frequently nominated author. With 12 papers, the Journal of the European Academy of Dermatology and Venereology contributed the most to the top 100 list. Alongside the term "acne", the following terms or phrases were observed frequency in the top 100 articles, Cutibacterium acnes, sebaceous, western diet, antibiotic resistance, staphylococcus-epidermidis, insulinlike growth factor 1, benzoyl peroxide, and polyunsaturated fatty acids. Alongside the term "acne", terms or phrases such as Cutibacterium acnes, sebaceous, western diet, antibiotic resistance, staphylococcus-epidermidis, insulinlike growth factor 1, benzoyl peroxide, and polyunsaturated fatty acids, etc also have a high frequency in the top 100 articles.

CONCLUSION

This analysis summarizes the shifting trends of acne research over the last decades. Research on acne is currently flourishing. The related pathogenesis and therapeutic strategies have been the focus of current research and developmental trends in future research.

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.

The causal relationship between gut microbiota and immune skin diseases: A bidirectional Mendelian randomization

BACKGROUND

Increasing evidence suggests that alterations in gut microbiota are associated with a variety of skin diseases. However, whether this association reflects a causal relationship remains unknown. We aimed to reveal the causal relationship between gut microbiota and skin diseases, including psoriasis, atopic dermatitis, acne, and lichen planus.

METHODS

We obtained full genetic association summary data for gut microbiota, psoriasis, atopic dermatitis, acne, and lichen planus from public databases and used three methods, mainly inverse variance weighting, to analyze the causal relationships between gut microbiota and these skin diseases using bidirectional Mendelian randomization, as well as sensitivity and stability analysis of the results using multiple methods.

RESULTS

The results showed that there were five associated genera in the psoriasis group, seven associated genera were obtained in the atopic dermatitis group, a total of ten associated genera in the acne group, and four associated genera in the lichen planus group. The results corrected for false discovery rate showed that Eubacteriumfissicatenagroup (P = 2.20E-04, OR = 1.24, 95%CI:1.11-1.40) and psoriasis still showed a causal relationship. In contrast, in the reverse Mendelian randomization results, there was no evidence of an association between these skin diseases and gut microbiota.

CONCLUSION

We demonstrated a causal relationship between gut microbiota and immune skin diseases and provide a new therapeutic perspective for the study of immune diseases: targeted modulation of dysregulation of specific bacterial taxa to prevent and treat psoriasis, atopic dermatitis, acne, and lichen planus.

Spatial transcriptomics reveals altered lipid metabolism and inflammation-related gene expression of sebaceous glands in psoriasis and atopic dermatitis

Sebaceous glands drive acne, however, their role in other inflammatory skin diseases remains unclear. To shed light on their potential contribution to disease development, we investigated the spatial transcriptome of sebaceous glands in psoriasis and atopic dermatitis patients across lesional and non-lesional human skin samples. Both atopic dermatitis and psoriasis sebaceous glands expressed genes encoding key proteins for lipid metabolism and transport such as ALOX15B, APOC1, FABP7, FADS1/2, FASN, PPARG, and RARRES1. Also, inflammation-related SAA1 was identified as a common spatially variable gene. In atopic dermatitis, genes mainly related to lipid metabolism (e.g. ACAD8, FADS6, or EBP) as well as disease-specific genes, i.e., Th2 inflammation-related lipid-regulating HSD3B1 were differentially expressed. On the contrary, in psoriasis, more inflammation-related spatially variable genes (e.g. SERPINF1, FKBP5, IFIT1/3, DDX58) were identified. Other psoriasis-specific enriched pathways included lipid metabolism (e.g. ACOT4, S1PR3), keratinization (e.g. LCE5A, KRT5/7/16), neutrophil degranulation, and antimicrobial peptides (e.g. LTF, DEFB4A, S100A7-9). In conclusion, our results show that sebaceous glands contribute to skin homeostasis with a cell type-specific lipid metabolism, which is influenced by the inflammatory microenvironment. These findings further support that sebaceous glands are not bystanders in inflammatory skin diseases, but can actively and differentially modulate inflammation in a disease-specific manner.

Association of different cell types and inflammation in early acne vulgaris

Acne vulgaris, one of the most common skin diseases, is a chronic cutaneous inflammation of the upper pilosebaceous unit (PSU) with complex pathogenesis. Inflammation plays a central role in the pathogenesis of acne vulgaris. During the inflammatory process, the innate and adaptive immune systems are coordinately activated to induce immune responses. Understanding the infiltration and cytokine secretion of differential cells in acne lesions, especially in the early stages of inflammation, will provide an insight into the pathogenesis of acne. The purpose of this review is to synthesize the association of different cell types with inflammation in early acne vulgaris and provide a comprehensive understanding of skin inflammation and immune responses.

AgNPs-Modified Polylactic Acid Microneedles: Preparation and In Vivo/In Vitro Antimicrobial Studies

OBJECTIVE

To prepare polylactic acid microneedles (PLAMNs) with sustained antibacterial effect to avoid skin infection caused by traditional MNs-based biosensors.

METHODS

Silver nanoparticles (AgNPs) were synthesized using an in-situ reduction process with polydopamine (PDA). PLAMNs were fabricated using the hot-melt method. A series of pressure tests and puncture experiments were conducted to confirm the physicochemical properties of PLAMNs. Then AgNPs were modified on the surface of PLAMNs through in-situ reduction of PDA, resulting in the formation of PLAMNs@PDA-AgNPs. The in vitro antibacterial efficacy of PLAMNs@PDA-AgNPs was evaluated using agar diffusion assays and bacterial liquid co-culture approach. Wound healing and simulated long-term application were performed to assess the in vivo antibacterial effectiveness of PLAMNs@PDA-AgNPs.

RESULTS

The MNs array comprised 169 tiny needle tips in pyramidal rows. Strength and puncture tests confirmed a 100% puncture success rate for PLAMNs on isolated rat skin and tin foil. SEM analysis revealed the integrity of PLAMNs@PDA-AgNPs with the formation of new surface substances. EDS analysis indicated the presence of silver elements on the surface of PLAMNs@PDA-AgNPs, with a content of 14.44%. Transepidermal water loss (TEWL) testing demonstrated the rapid healing of micro-pores created by PLAMNs@PDA-AgNPs, indicating their safety. Both in vitro and in vivo tests confirmed antibacterial efficacy of PLAMNs@PDA-AgNPs.

CONCLUSIONS

In conclusion, the sustained antibacterial activity exhibited by PLAMNs@PDA-AgNPs offers a promising solution for addressing skin infections associated with MN applications, especially when compared to traditional MN-based biosensors. This advancement offers significant potential for the field of MN technology.

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.

Genetic perspectives on the influence of circulating cytokines on acne: A Mendelian randomization study

Previous studies have reported that the occurrence and development of acne are closely associated with immune-inflammatory responses. Mendelian randomization was performed to further assess the causal correlation between 41 inflammatory cytokines and acne. Mendelian two-sample randomization utilized genetic variants for acne from a large open genome-wide association study (1299 cases and 211,139 controls of European ancestry) and inflammatory cytokines from a genome-wide association study abstract containing 8293 healthy participants. The causal relationship between exposure and outcome was explored primarily using an inverse variance weighting approach. In addition, multiple sensitivity analyses including MR-Egger, weighted median, simple model, weighted model, and MR-PRESSO were applied simultaneously to enhance the final results. The results suggest that il-10, MIP-1A, and SCGF-β are suggestive of the risk of acne in clinical practice (OR = 0.799, 95% CI = 0.641-0.995, P = .045; OR = 0.55, 95% CI = 0.388-0.787, P = .001; OR = 1. 152, 95% CI = 1.001-1.325, P = .048). Our study conclusively identified a causal relationship between il-10 and circulating levels of acne risk and a suggestive link between MIP-1A and SCGF-β and acne. Our study may provide greater insight into the pathogenesis of acne and develop effective management strategies for the clinic. We believe that IL-10, MIP-1A, and SCGF-β could be potential therapeutic targets for acne development.

Improvements in acne and skin oiliness with tazarotene 0.045% lotion in patients with oily skin

BACKGROUND

Excessive sebum production is a factor in acne development. Tazarotene 0.045% lotion has demonstrated reductions in acne lesions and acne-induced sequelae.

OBJECTIVE

Evaluate efficacy, changes in skin oiliness, and safety with tazarotene 0.045% lotion in participants with moderate-to-severe acne and oily skin.

METHODS

In two phase 3, double-blind, 12-week studies (NCT03168321; NCT03168334), participants aged ≥ 9 years with moderate-to-severe acne were randomized 1:1 to once-daily tazarotene 0.045% lotion or vehicle lotion (N = 1614). This pooled, post hoc analysis included only participants self-categorized with oily skin at baseline on the Acne-Specific Quality of Life questionnaire item 19 (scores: 0 [extremely oily] to 6 [not at all oily]). Inflammatory/noninflammatory lesion counts, treatment success, skin oiliness, treatment-emergent adverse events (TEAEs), and cutaneous safety/tolerability were evaluated.

RESULTS

In all participants with oily skin (n = 793), tazarotene provided greater reductions in inflammatory/noninflammatory lesions (p < 0.001, both) and greater treatment success rates versus vehicle (p < 0.01) at week 12. Over two-thirds of polymeric lotion-treated participants had subjective skin oiliness reductions by week 12, with around a third reporting 'low/not' oily skin. Tazarotene TEAE rates were similar to the overall population.

CONCLUSIONS

Once-daily treatment with tazarotene 0.045% polymeric emulsion lotion may help improve patient-perceived skin oiliness in those with moderate-to-severe acne.

Comprehensive assessment of the efficacy and safety of a clay mask in oily and acne skin

BACKGROUND

Oily skin, characterized by excessive sebum production, can lead to acne and have psychosocial impacts due to changes in appearance. Recent research has shown interest in treatments for oil control, with kaolin and bentonite emerging as promising options. Despite their potential, comprehensive studies on these ingredients are still in the nascent stages.

AIM

This study aimed to assess the efficacy of a clay mask (La Roche-Posay Effaclar Sebo-Controlling Mask) in reducing skin oiliness and acne, and its safety for use.

METHODS

In this study, 75 adults with oily or combination skin were enrolled and provided with a clay mask for twice-weekly use over 4 weeks. Clinical assessments, using instruments like Sebumeter, Vapometer, and Corneometer, were conducted at baseline, and after 1, 2, and 4 weeks, evaluating acne lesions, skin irritation, sebum content, and skin hydration. Participant self-assessment questionnaires were also utilized for subjective evaluation. Statistical analyses were performed accordingly.

RESULTS

The study revealed significant improvements in acne-related outcomes, sebum content, skin evenness, stratum corneum water content, and transepidermal water loss following the application of the clay mask. Pore area and porphyrin area showed no significant changes. Tolerance assessment showed reduced dryness and irritation, with self-assessment indicating high product acceptability and perceived oil control effectiveness.

CONCLUSION

This study demonstrated the clay mask's efficacy in managing acne and oily skin, improving hydration and texture. Significant improvements in skin parameters and high product safety were observed, supporting its suitability.

DNA methylation profiling and integrative multi-omics analysis of skin samples reveal important contribution of epigenetics and immune response in the pathogenesis of acne vulgaris

The regulatory effect of DNA methylation on the pathogenesis of acne vulgaris is completely unknown. Herein we analyzed the DNA methylation profile in skin samples of acne vulgaris and further integrated it with gene expression profiles and single-cell RNA-sequencing data. Finally, 31,134 differentially methylated sites and 770 differentially methylated and expressed genes (DMEGs) were identified. The multi-omics analysis suggested the importance of DNA methylation in inflammation and immunity in acne. And DMEGs were verified in an external dataset and were closely related to early inflammatory acne. Additionally, we conducted experiments to verify the mRNA expression and DNA methylation level of DMEGs. This study supports the significant contribution of epigenetics to the pathogenesis of acne vulgaris and may provide new ideas for the molecular mechanisms of and potential therapeutic strategies for acne vulgaris.

Cross-Sectional Assessment of Dermatologists' Knowledge and Attitude Towards Isotretinoin-Related Ocular Side Effects in Aseer, Saudi Arabia

BACKGROUND

Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit, which includes the hair follicle, hair shaft and sebaceous gland. The only treatment that has an effect on all the main aetiological causes of acne is isotretinoin. However, it may have a variety of negative side effects. The aim of this study was to evaluate the knowledge and attitudes of dermatologists regarding ocular effects following isotretinoin prescribing in the Aseer region, Saudi Arabia.

METHODOLOGY

An anonymous online cross-sectional survey was conducted in August 2022 to investigate dermatologists' knowledge and attitude regarding isotretinoin-related ocular side effects in Aseer, Saudi Arabia. Participants were recruited using convenience and snowball sampling methods.

RESULTS

A total of 48 dermatologists were included in this survey. The age distribution ranged from 25 to over 60 years. Sixteen (37.5%) were aged 31-40 years, 29 (60.4%) were male and 20 (41.7%) were specialists. All dermatologists reported that it can cause dry eye, 32 (66.7%) reported that it can cause contact lens intolerance, 10 (20.8%) reported that it can cause a decrease in dark adaptation and two (4.2%) thought that it can cause ectopia lentis and retinoblastoma. Regarding attitude, 43 (87.5%) thought that a course of isotretinoin is not recommended if the patient has recently undergone refractive surgery, 30 (62.5%) always inform patients about ocular side effects, 31 (72.9%) do not consider referring patients for ophthalmic examinations before initiating isotretinoin, 12 (25.0%) always prescribe lubricant eye drops, 15 (31.3%) always ask patients about recent refractive surgery, 17 (35.4%) always warn patients about avoiding refractive surgery during isotretinoin use and 19 (39.6%) always inform patients concerning discomfort with contact lenses.

CONCLUSIONS

The survey reveals that dermatologists in Aseer, Saudi Arabia, generally have good knowledge of isotretinoin related to some ocular side effects, especially dry eye and contact lens intolerance. However, there is some variation in their practices with regard to patient education, referrals for ophthalmic examinations, the use of lubricant eye drops and refractive surgery during isotretinoin treatment. Thus, dermatologists should receive educational training on the safety profile of isotretinoin while managing acne vulgaris.

Changes in the skin microbiome during male maturation from 0 to 25 years of age

BACKGROUND

Skin microorganisms co-develop with the human body and age influences the skin microenvironment and thus the skin bacterial community.

OBJECTIVES

To investigate the changes in the skin microbiota during male development.

METHODS

High-throughput 16S ribosomal RNA pyrosequencing was utilized to analyze the differences in bacterial composition of the skin in healthy males aged 0-25 years.

RESULTS

There were significant differences in facial skin bacterial diversity (Shannon index) and richness (Chao index) among the 4 groups of subjects (p < 0.05). Streptococcus, Staphylococcus, Cutibacterium are dominant in males during growth, and regular changes occur with age after birth. Further analysis of skin bacteria between the 4 groups showed that the bacterial abundance of Cutibacterium acnes and Staphylococcus epidermidis tended to increase with age, and the bacterial abundance of Streptococcus, Rothia mucilaginosa, and Staphylococcus hominis tended to decrease with age.

CONCLUSIONS

There are some changes in cheek skin bacterial diversity during male development, and there is a relationship between skin bacterial changes and skin development processes.

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.

Targeting Inflammation in Acne: Current Treatments and Future Prospects

Acne is a common, chronic inflammatory condition affecting millions of people worldwide, with significant negative impact on quality of life and mental health. Acne is characterized by comedones, inflammatory papules, pustules, and nodulocystic lesions, with long-lasting sequelae including scarring and dyspigmentation, the latter of which is more common in skin of color. The four main pillars of acne pathophysiology include alteration of sebum production and concentration, hyperkeratinization of the follicular unit, Cutibacterium acnes strains, and an inflammatory immune response. Newer research has provided greater insight into these pathophysiologic categories. This greater understanding of acne pathogenesis has led to numerous new and emerging treatment modalities. These modalities include combinations of existing treatments, repurposing of existing agents historically used for other conditions, new topical treatments, novel antibiotics, topical and oral probiotics, and various procedural devices. This article will provide an overview of emerging treatments of acne and their link to our current and improved understanding of acne pathogenesis.

Lipid Metabolism Reprogramming of Immune Cells in Acne: An Update

Acne vulgaris is one of the most widespread skin conditions and the main reason for visiting a dermatologist. Inflammatory response and abnormal infiltrations of immune cells are the main pathogenesis of acne. The increased lipid is the prerequisite for the acne, and the perturbation of lipid composition and content is consistent with the severity of acne. Furthermore, the increased lipid production not only contributes to the occurrence and development of acne, but also sensitizes the function of immune cells. The lipid metabolic dysfunction aggravates the severity of local tissue and provides pro-inflammatory-cytokine cues, which indicates the crucial roles of lipid metabolism on immune cells. Recent advances have demonstrated the lipid metabolism reprogramming of various immune cells in acne lesion. The abnormal lipid accumulation, lipolysis, and fatty acid oxidation lead to the activation and differentiation of immune cells, which promotes the pro-inflammatory cytokines production. Thus, this review discusses the emerging role of lipid metabolism reprogramming of immune cells in the progress of acne and aims to constitute food for others' projects involved in acne research.

Gut microbiota and acne: A Mendelian randomization study

BACKGROUND

Prior observational studies have identified a relationship between the composition of gut microbiota and the onset of acne. To ascertain the causal relationship underlying this association, we adopted the Mendelian randomization (MR) method, which offers a powerful approach to causal inference.

METHODS

Summary statistics on gut microbiota and acne were obtained from the MiBioGen and FinnGen consortium, respectively. The causal relationship was assessed using multiple methods in a two-sample framework, including MR Egger, weighted median, inverse variance weighted (IVW), and weighted mode. Furthermore, the heterogeneity and horizontal pleiotropy analyses were conducted, along with the leave-one-out method.

RESULTS

The IVW estimation indicated that Allisonella (odds ratio [OR] = 1.42, 95% confidence interval [CI] = 1.18-1.70, p = 0.0002) and Bacteroides (OR = 2.25, 95% CI = 1.48-3.42, p = 0.0001) have adverse effects on acne. By contrast, Ruminococcus torques group (OR = 0.41, 95% CI = 0.25-0.65, p = 0.0002) showed a beneficial effect on acne. In addition, Candidatus soleaferrea (OR = 0.75, 95% CI = 0.60-0.95, p = 0.0149), Eubacterium coprostanoligenes group (OR = 0.67, 95% CI = 0.47-0.95, p = 0.0230), Fusicatenibacter (OR = 0.71, 95% CI = 0.52-0.97, p = 0.02897), and Lactobacillus (OR = 0.72, 95% CI = 0.58-0.90, p = 0.0046) showed suggestive associations with acne.

CONCLUSION

The present investigation suggests a causal effect of gut microbiota on acne.

Effects of Moringa oleifera Seed Oil on Cultured Human Sebocytes In Vitro and Comparison with Other Oil Types

The seeds of Moringa oleifera (horseradish tree) contain about 40% of one of the most stable vegetable oils (Moringa seed oil). Therefore, the effects of Moringa seed oil on human SZ95 sebocytes were investigated and were compared with other vegetable oils. Immortalized human SZ95 sebocytes were treated with Moringa seed oil, olive oil, sunflower oil, linoleic acid and oleic acid. Lipid droplets were visualized by Nile Red fluorescence, cytokine secretion via cytokine antibody array, cell viability with calcein-AM fluorescence, cell proliferation by real-time cell analysis, and fatty acids were determined by gas chromatography. Statistical analysis was performed by the Wilcoxon matched-pairs signed-rank test, the Kruskal-Wallis test and Dunn's multiple comparison test. The vegetable oils tested stimulated sebaceous lipogenesis in a concentration-dependent manner. The pattern of lipogenesis induced by Moringa seed oil and olive oil was comparable to lipogenesis stimulated by oleic acid with also similar fatty acid secretion and cell proliferation patterns. Sunflower oil induced the strongest lipogenesis among the tested oils and fatty acids. There were also differences in cytokine secretion, induced by treatment with different oils. Moringa seed oil and olive oil, but not sunflower oil, reduced the secretion of pro-inflammatory cytokines, in comparison to untreated cells, and exhibited a low n-6/n-3 index. The anti-inflammatory oleic acid detected in Moringa seed oil probably contributed to its low levels of pro-inflammatory cytokine secretion and induction of cell death. In conclusion, Moringa seed oil seems to concentrate several desired oil properties on sebocytes, such as high content level of the anti-inflammatory fatty acid oleic acid, induction of similar cell proliferation and lipogenesis patterns compared with oleic acid, lipogenesis with a low n-6/n-3 index and inhibition of secretion of pro-inflammatory cytokines. These properties characterize Moringa seed oil as an interesting nutrient and a promising ingredient in skin care products.

Exploring the mechanism of action of Hedyotis diffusa Willd on acne using network analysis

In this study, we used a network pharmacological method to explore the active ingredients of Hedyotis diffusa Willd (HDW) in the treatment of acne and elucidated the physiological mechanisms in the human body in which they are involved. We identified the active compounds of HDW that are expected to act effectively in the human body using the Traditional Chinese Medicine Systems Pharmacology database and analysis platform and extracted potential interacting proteins for each active compound using the Swiss Target Prediction platform. Next, we analyzed the potential mechanisms of action of the protein targets shared by HDW and each standard drug on acne and assessed the possibility of spontaneous occurrence of the binding between proteins and active compounds through the molecular docking process. Seven active compounds were selected according to the oral bioavailability and drug-likeness criteria of the Traditional Chinese Medicine Systems Pharmacology database and analysis platform. Subsequently, 300 protein targets were collected from the Swiss Target Prediction. Using the Search Tool for the Retrieval of Interacting Genes/Proteins database, a protein-protein interaction network was constructed by analyzing the relationship between HDW, acne, and each standard drug. By analyzing the gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathway, the "positive regulation of lipid metabolic process" was found to be the most involved pathway shared by HDW, acne, and isotretinoin. An analysis of the protein targets shared by the antibiotic agents with HDW and acne found that "cholesterol storage" in tetracycline, "icosacoid transport" in azithromycin, "steroid hydroxylase activity" in erythromycin, "positive regulation of leukocyte tethering or rolling" in clindamycin, "response to UV-A" in minocycline, "steroid 11-beta-monooxygenase activity" in doxycycline, and "neutrophil-mediated immunity" in trimethoprim were the most involved. Virtual molecular docking analysis showed that all proteins spontaneously bound to their corresponding active compounds. Our analysis suggests that HDW can, directly and indirectly, suppress sebum secretion and exert antiinflammatory effects on acne. Further, HDW may regulate free radicals and suppress apoptosis. Therefore, HDW can be used as an alternative or supplement to standard drugs for acne treatment in patients who cannot use standard treatments due to side effects.

Sun exposure, a relevant exposome factor in acne patients and how photoprotection can improve outcomes

BACKGROUND

Acne pathophysiology includes a complex interaction among inflammatory mediators, hyperseborrhea, alteration of keratinization and follicular colonization by Propionibacterium acnes.

AIMS

To describe the impact of the exposome on acne and how photoprotection can improve outcomes.

METHODS

A narrative review of the literature was carried out; searches with Google Scholar and Pubmed from January 1992 to November 2022 were performed. The keywords used were "acne," "sunscreens," "photoprotection," "cosmetics," "cosmeceuticals," "pathogenesis," "etiology," "exposome," "sunlight," "stress," "lack of sleep," "diet," "postinflammatory hyperpigmentation," "pollution," "exposome," "ultraviolet radiation," and "visible light."

RESULTS

Environmental factors such as solar radiation, air pollution, tobacco consumption, psychological stress, diverse microorganisms, nutrition, among others, can trigger or worsen acne. Solar radiation can temporarily improve lesions. However, it can induce proinflammatory and profibrotic responses, and produce post-inflammatory hyperpigmentation and/or post-inflammatory erythema. While photoprotection is widely recommended to acne patients, only four relevant studies were found. Sunscreens can significantly improve symptomatology or enhance treatment and can prevent post-inflammatory hyperpigmentation. Furthermore, they can provide camouflage and improve quality of life. Based on acne pathogenesis, optimal sunscreens should have emollient, antioxidant and sebum controlling properties.

CONCLUSIONS

The exposome and solar radiation can trigger or worsen acne. UV light can induce post-inflammatory hyperpigmentation/erythema, and can initiate flares. The use of specifically formulated sunscreens could enhance adherence to topical or systemic therapy, camouflage lesions (tinted sunscreens), decrease inflammation, and reduce the incidence of post-inflammatory hyperpigmentation/erythema.

Desaturation of sebaceous-type saturated fatty acids through the SCD1 and the FADS2 pathways impacts lipid neosynthesis and inflammatory response in sebocytes in culture

Sebum is a lipid-rich mixture secreted by the sebaceous gland (SG) onto the skin surface. By penetrating through the epidermis, sebum may be involved in the regulation of epidermal and dermal cells in both healthy and diseased skin conditions. Saturated and monounsaturated fatty acids (FAs), found as free FAs (FFAs) and in bound form in neutral lipids, are essential constituents of sebum and key players of the inflammatory processes occurring in the pilosebaceous unit in acne-prone skin. Little is known on the interplay among uptake of saturated FFAs, their biotransformation, and induction of proinflammatory cytokines in sebocytes. In the human SG, palmitate (C16:0) is the precursor of sapienate (C16:1n-10) formed by insertion of a double bond (DB) at the Δ6 position catalysed by the fatty acid desaturase 2 (FADS2) enzyme. Conversely, palmitoleate (C16:1n-7) is formed by insertion of a DB at the Δ9 position catalysed by the stearoyl coenzyme A desaturase 1 (SCD1) enzyme. Other FFAs processed in the SG, also undergo these main desaturation pathways. We investigated lipogenesis and release of IL-6 and IL-8 pro-inflammatory cytokines in SZ95 sebocytes in vitro after treatment with saturated FFAs, that is, C16:0, margarate (C17:0), and stearate (C18:0) with or without specific inhibitors of SCD1 and FADS2 desaturase enzymes, and a drug with mixed inhibitory effects on FADS1 and FADS2 activities. C16:0 underwent extended desaturation through both SCD1 and FADS2 catalysed pathways and displayed the strongest lipoinflammatory effects. Inhibition of desaturation pathways proved to enhance lipoinflammation induced by SFAs in SZ95 sebocytes. Palmitate (C16:0), margarate (C17:0), and stearate (C18:0) are saturated fatty acids that induce different arrays of neutral lipids (triglycerides) and dissimilar grades of inflammation in sebocytes.

Inhibition of lipogenesis and sebum secretion for Lotus corniculatus seed extract in vitro and in vivo

BACKGROUND

Botanical ingredients are widely used in hair- and skin-care products. However, few studies have investigated the effectiveness of botanical products on counteracting sebum synthesis and secretion.

OBJECTIVE

To investigate the composition of Lotus corniculatus seed extract (LC) and its potential inhibition of lipogenesis in SZ95 sebocytes and oily human skin.

METHODS

The active components of LC solutions were identified by high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). The in vitro effects of LC were evaluated using SZ95 cells treated with linoleic acid (LA) and dihydrotestosterone (DHT) and incubated with LCs for 24 h and 72 h. Lipogenesis was assessed by Oil Red O and Nile Red staining of the cells. In vivo effects were assessed on 30 subjects with oily skin who were enrolled in a randomized, blank-controlled trial and were treated with LC solution for 6 h and 4 weeks. The skin sebum contents and area on the forehead and cheeks were evaluated using a Sebumeter SM815 and Sebfix sebutape with Visioscan VC98. In addition, VISIA was used to collect half-face photos for analysis.

RESULTS

A novel active molecule, 5'-o-rhamnosyl uridine, was identified in LC. LC exhibited a dose-dependent inhibitory effect on LA and DHT-induced lipid synthesis. When 5% LC was applied for 3 h, the skin sebum contents and area were significantly reduced compared with the vehicle control, with an obvious reduction after 6 h. Continued use of the serum containing 5% LC for 4 weeks resulted in a significant reduction in the skin sebum contents and area. No adverse reactions were reported during the study.

CONCLUSIONS

Topical application of LC resulted in an immediate and long-lasting reduction of the sebum contents and area of oily human skin by reducing sebaceous lipogenesis through the LA and DHT pathways. This indicates the potential of LC as a new biological treatment for oily skin.

Probiotics in dermatological and cosmetic products – application and efficiency

The term “probiotics” has first been used in 1907 by Elie Metchnikoff. Since then, probiotics have been part of research not only in regards of digestive health, but also inflammatory diseases. Lately, there has been an increased interest of probiotic’s effects in skincare. The management of atopic dermatitis, acne, psoriasis, photo aging, skin cancer, intimate care, oral care, wound healing is getting harder each passing day, due to increased antibiotic resistance and other side effects of conventional therapy. Therefore, new ingredients have been investigated and probiotics have been proved to be effective in treating various skin conditions. This review aims to evaluate the scientific evidence on topical and oral probiotics, and to evaluate the efficacy of cosmetic and dermatological products containing probiotics. Many studies have shown that skin and gut microbiome alterations have an important role in skin health. Although this is a new topic in dermatology and cosmetology, there have been some promising results in lots of research studies that the use of probiotics in cosmetic products may help improve the patient’s outcome. While oral probiotics have been shown to promote gut health, which influences the host immune system and helps treat different skin diseases, the mechanism of action of topical probiotics is not yet fully understood. Although the number of commercial probiotic cosmetic products released in the market is increasing and most of the studies have not shown any serious side effect of probiotics, further studies, in larger and heterogeneous groups are needed.

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

BACKGROUND

The composition of the skin microbiome varies from infancy to adulthood and becomes most stable in adulthood. Adult acne patients harbour an 'acne microbiome' dominated by specific strains of Cutibacterium acnes. However, the precise timing of skin microbiome evolution, the development of the acne microbiome, and the shift to virulent C. acnes strain composition during puberty is unknown.

OBJECTIVES

We performed a cross-sectional pilot study in a paediatric population to understand how and when the skin microbiome composition transitions during puberty and whether a distinct 'acne microbiome' emerges in paediatric subjects.

METHODS

Forty-eight volunteers including males and females, ages 7-17 years, with and without acne were enrolled and evaluated for pubertal development using the Tanner staging criteria. Sebum levels were measured, and skin microbiota were collected by sterile swab on the subject's forehead. DNA was sequenced by whole genome shotgun sequencing.

RESULTS

A significant shift in microbial diversity emerged between early (T1-T2) and late (T3-T5) stages of puberty, coinciding with increased sebum production on the face. The overall relative abundance of C. acnes in both normal and acne skin increased during puberty and individual C. acnes strains were uniquely affected by pubertal stage and the presence of acne. Further, an acne microbiome signature associated with unique C. acnes strain composition and metabolic activity emerges in late puberty in those with acne. This unique C. acnes strain composition is predicted to have increased porphyrin production, which may contribute to skin inflammation.

CONCLUSIONS

Our data suggest that the stage of pubertal development influences skin microbiome composition. As children mature, a distinct acne microbiome composition emerges in those with acne. Understanding how both puberty and acne influence the microbiome may support novel therapeutic strategies to combat acne in the paediatric population.

Serum and salivary adipsin levels and its association with insulin resistance in acne vulgaris patients

BACKGROUND

There is scarcity in literature about the reliability of salivary markers in acne vulgaris.

AIMS

The aims were to evaluate the insulin resistance (IR) and adipsin levels in serum and saliva in a sample of acne vulgaris patients; and to correlate IR and adipsin levels with the disease severity.

METHODS

This prospective case-control study included 60 acne vulgaris patients (patients Group), in addition, 60 apparently healthy individuals (control group). The severity of acne vulgaris was determined according to Global Acne Grading system (GAGS). Serum and salivary adipsin, fasting glucose, and fasting insulin levels were measured using ELISA kits.

RESULTS

Fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) in patients group both in serum and saliva were elevated when compared with the control group. Serum and salivary levels of adipsin and Quantitative insulin sensitivity check index (QUIKI) in patients were decreased than the control group. Adipsin serum levels show significant negative correlations with all study variables except QUIKI with which the correlation was positive both in serum and saliva. There was a significant positive correlation between serum and salivary adipsin levels (r = 0.873, p < 0.00001) and serum and salivary fasting glucose (r = 1, p < 0.00001).

CONCLUSION

Adipsin could be considered as a promising biomarker for acne vulgaris and its associated insulin resistance. Moreover, the salivary measurements may be considered as useful biomarkers in acne vulgaris patients, but more studies are still required.

Adipose-derived stem cells attenuate acne-related inflammation via suppression of NLRP3 inflammasome

Background

Acne is a chronic facial disease caused by Propionibacterium acnes, which proliferates within sebum-blocked skin follicles and increases inflammatory cytokine production. Several therapeutic drugs and products have been proposed to treat acne, yet no single treatment that ensures long-term treatment efficacy for all patients is available. Here, we explored the use of facial autologous fat transplant of adipose-derived stem cells (ADSCs) to dramatically reduce acne lesions.

Methods

THP-1 cells were treated with active P. acnes for 24 h at different multiplicities of infection, and alterations in inflammatory factors were detected. To study the effect of THP-1 on inflammasome-related proteins, we first co-cultured ADSCs with THP-1 cells treated with P. acnes and evaluated the levels of these proteins in the supernatant. Further, an acne mouse model injected with ADSCs was used to assess inflammatory changes.

Results

Propionibacterium acnes-mediated stimulation of THP-1 cells had a direct correlation with the expression of active caspase-1 and interleukin (IL)-1β in an infection-dependent manner. ADSCs significantly reduced the production of IL-1β induced by P. acnes stimulation through the reactive oxygen species (ROS)/Nod-like receptor family pyrin domain-containing 3 (NLRP3)/caspase-1 pathway. The results showed that ADSCs inhibit the skin inflammation induced by P. acnes by blocking the NLRP3 inflammasome via reducing the secretion of IL-1β in vivo.

Conclusions

Our findings suggest that ADSCs can alter IL-1β secretion by restricting the production of mitochondria ROS, thereby inhibiting the NLRP3/caspase-1 pathway in P. acnes-induced inflammatory responses. This study indicates that anti‐acne therapy can potentially be developed by targeting the NLRP3 inflammasome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03007-7.

Sebaceous immunobiology - skin homeostasis, pathophysiology, coordination of innate immunity and inflammatory response and disease associations

This review presents several aspects of the innovative concept of sebaceous immunobiology, which summarizes the numerous activities of the sebaceous gland including its classical physiological and pathophysiological tasks, namely sebum production and the development of seborrhea and acne. Sebaceous lipids, which represent 90% of the skin surface lipids in adolescents and adults, are markedly involved in the skin barrier function and perifollicular and dermal innate immune processes, leading to inflammatory skin diseases. Innovative experimental techniques using stem cell and sebocyte models have clarified the roles of distinct stem cells in sebaceous gland physiology and sebocyte function control mechanisms. The sebaceous gland represents an integral part of the pilosebaceous unit and its status is connected to hair follicle morphogenesis. Interestingly, professional inflammatory cells contribute to sebocyte differentiation and homeostasis, whereas the regulation of sebaceous gland function by immune cells is antigen-independent. Inflammation is involved in the very earliest differentiation changes of the pilosebaceous unit in acne. Sebocytes behave as potent immune regulators, integrating into the innate immune responses of the skin. Expressing inflammatory mediators, sebocytes also contribute to the polarization of cutaneous T cells towards the Th17 phenotype. In addition, the immune response of the perifollicular infiltrate depends on factors produced by the sebaceous glands, mostly sebaceous lipids. Human sebocytes in vitro express functional pattern recognition receptors, which are likely to interact with bacteria in acne pathogenesis. Sex steroids, peroxisome proliferator-activated receptor ligands, neuropeptides, endocannabinoids and a selective apoptotic process contribute to a complex regulation of sebocyte-induced immunological reaction in numerous acquired and congenital skin diseases, including hair diseases and atopic dermatitis.

Transcriptome Analysis of Particulate Matter 2.5-Induced Abnormal Effects on Human Sebocytes

Particulate matter 2.5 (PM2.5), an atmospheric pollutant with an aerodynamic diameter of <2.5 μm, can cause serious human health problems, including skin damage. Since sebocytes are involved in the regulation of skin homeostasis, it is necessary to study the effects of PM2.5 on sebocytes. We examined the role of PM2.5 via the identification of differentially expressed genes, functional enrichment and canonical pathway analysis, upstream regulator analysis, and disease and biological function analysis through mRNA sequencing. Xenobiotic and lipid metabolism, inflammation, oxidative stress, and cell barrier damage-related pathways were enriched; additionally, PM2.5 altered steroid hormone biosynthesis and retinol metabolism-related pathways. Consequently, PM2.5 increased lipid synthesis, lipid peroxidation, inflammatory cytokine expression, and oxidative stress and altered the lipid composition and expression of factors that affect cell barriers. Furthermore, PM2.5 altered the activity of sterol regulatory element binding proteins, mitogen-activated protein kinases, transforming growth factor beta-SMAD, and forkhead box O3-mediated pathways. We also suggest that the alterations in retinol and estrogen metabolism by PM2.5 are related to the damage. These results were validated using the HairSkin® model. Thus, our results provide evidence of the harmful effects of PM2.5 on sebocytes as well as new targets for alleviating the skin damage it causes.

Understanding the systemic burden of disease in hidradenitis suppurativa from plasma lipidomic analysis

BACKGROUND

Hidradenitis suppurativa (HS) is an inflammatory skin condition that is often considered a systemic disease due to its association with metabolic comorbidity.

OBJECTIVE

In this study, we aimed to identify differences in plasma lipidomic profiles between HS patients and control subjects.

METHODS

HS patients were recruited from a tertiary dermatological centre and demographic and comorbidity matched controls from the general population. A targeted lipidomic approach was performed to characterize over 700 lipid species representing 35 lipid classes/sub-classes. Linear regression models adjusted for confounding factors were used to compare the plasma lipidomic profiles of HS patients to controls. Ordinal regression models were used to study the association of lipids with disease activity and severity scores.

RESULTS

60 HS patients and 73 control subjects were recruited. Differential levels (p < 0.05) of 32 lipid species in HS patients compared to controls were observed, including a decrease in the long chain base d19:1 containing ceramides, and elevation of hydroxyeicosatetraenoic acid (HETE) and dihydroxyeicosatrienoic acid (DHET) oxylipins. These lipids along with several other molecules showed associations with Hurley, HS-PGA and disease activity scores.

CONCLUSION

This study found mild changes in plasma lipidomic profiles, consistent with previous studies showing attenuated metabolomic changes in plasma as opposed to lesional skin. However, a number of lipid species were associated with increasing activity and severity of the disease. Further, the significant lipid species within the same class showed consistent trends of increase or decrease in HS as compared to controls.

Potential roles of gut microbial tryptophan metabolites in the complex pathogenesis of acne vulgaris

Acne vulgaris is a chronic inflammatory skin disease in which the influence of gut microbiota has been implicated but without clarification of mechanisms. Gut microbiota may exert such an influence via metabolites, particularly those of tryptophan. End metabolites of tryptophan activate receptors, including aryl hydrocarbon, G protein-coupled, and pregnane X receptors to stabilize the immune microenvironment and intestinal mucosal homeostasis. Any impact on the pathogenesis of acne vulgaris remains unclear. The current review collates recent advances concerning potential roles of tryptophan metabolism in mediating skin inflammation, follicular sebaceous gland function and intestinal permeability, all of which influence the pathogenesis of acne vulgaris. The aim was to improve understanding of the pathogenesis of acne vulgaris and to expose therapeutic opportunities.

TREM2 macrophages induced by human lipids drive inflammation in acne lesions

Acne affects 1 in 10 people globally, often resulting in disfigurement. The disease involves excess production of lipids, particularly squalene, increased growth of Cutibacterium acnes, and a host inflammatory response with foamy macrophages. By combining single-cell and spatial RNA sequencing as well as ultrahigh-resolution Seq-Scope analyses of early acne lesions on back skin, we identified TREM2 macrophages expressing lipid metabolism and proinflammatory gene programs in proximity to hair follicle epithelium expressing squalene epoxidase. We established that the addition of squalene induced differentiation of TREM2 macrophages in vitro, which were unable to kill C. acnes. The addition of squalene to macrophages inhibited induction of oxidative enzymes and scavenged oxygen free radicals, providing an explanation for the efficacy of topical benzoyl peroxide in the clinical treatment of acne. The present work has elucidated the mechanisms by which TREM2 macrophages and unsaturated lipids, similar to their involvement in atherosclerosis, may contribute to the pathogenesis of acne.

Fatty Acid Profiling in Facial Sebum and Erythrocytes From Adult Patients With Moderate Acne

Fatty acid (FA) metabolism has been involved in acne vulgaris, a common inflammatory skin disease frequently observed in adolescents and adults, but it remains poorly defined whether the distributions or location of FA in facial sebum and those in the circulation differentially correlate with the disease. In a cohort of 47 moderate acne patients and 40 controls, sebum samples from forehead and chin areas were collected using Sebutape adhesive patches, and erythrocytes were separated from the fasting blood. Total FAs were analyzed by the gas chromatograph-mass spectrometry method. Compared to control female subjects, female patients showed increased levels of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) from both facial areas, whereas decreased levels of polyunsaturated fatty acids (PUFAs) from chin areas were observed. Interestingly, the levels of docosahexaenoic acid (DHA) in the circulating erythrocytes were significantly decreased in male patients compared with control. In addition, DHA levels in erythrocytes were positively correlated with PUFAs from sebum only in male subjects. Furthermore, female patients with moderate acne had more severe sebum abnormity and chin-specific FA profiles, consistent with higher acne incidences than males in adulthood, especially in the chin areas. Importantly, serum insulin-like growth factor 1 (IGF-1) levels were positively correlated with SFAs and MUFAs from sebum only in male subjects. In summary, differential spatial FA distributions in facial sebum and correlation with those in erythrocytes and IGF1 levels in serum may shed some light on the pathology of acne in male and female adults.

Cannabis-Based Products for the Treatment of Skin Inflammatory Diseases: A Timely Review

The use of natural products in dermatology is increasingly being pursued due to sustainability and ecological issues, and as a possible way to improve the therapeutic outcome of chronic skin diseases, relieving the burden for both patients and healthcare systems. The legalization of cannabis by a growing number of countries has opened the way for researching the use of cannabinoids in therapeutic topical formulations. Cannabinoids are a diverse class of pharmacologically active compounds produced by Cannabis sativa (phytocannabinoids) and similar molecules (endocannabinoids, synthetic cannabinoids). Humans possess an endocannabinoid system involved in the regulation of several physiological processes, which includes naturally-produced endocannabinoids, and proteins involved in their transport, synthesis and degradation. The modulation of the endocannabinoid system is a promising therapeutic target for multiple diseases, including vascular, mental and neurodegenerative disorders. However, due to the complex nature of this system and its crosstalk with other biological systems, the development of novel target drugs is an ongoing challenging task. The discovery of a skin endocannabinoid system and its role in maintaining skin homeostasis, alongside the anti-inflammatory actions of cannabinoids, has raised interest in their use for the treatment of skin inflammatory diseases, which is the focus of this review. Oral treatments are only effective at high doses, having considerable adverse effects; thus, research into plant-based or synthetic cannabinoids that can be incorporated into high-quality, safe topical products for the treatment of inflammatory skin conditions is timely. Previous studies revealed that such products are usually well tolerated and showed promising results for example in the treatment of atopic dermatitis, psoriasis, and contact dermatitis. However, further controlled human clinical trials are needed to fully unravel the potential of these compounds, and the possible side effects associated with their topical use.

Female Adult Acne and Androgen Excess: A Report From the Multidisciplinary Androgen Excess and PCOS Committee

In endocrine and reproductive endocrine literature, adult female acne is considered as a possible clinical expression of hyperandrogenism, with most polycystic ovary syndrome (PCOS) guidelines considering acne as a condition of androgen excess. Adult female acne, however, in the dermatological literature is considered as an inflammatory skin disease and new guidelines on adult female acne have been produced by dermatological societies, with little perspective from any endocrine or reproductive endocrine points of view. An expert task force was appointed by the AE-PCOS society to determine the current state of knowledge and provide evidence-based recommendations that could be valid for all specialists taking care of female adult acne. The following are the recommendations (level of evidence A or B): (1) diagnosis of female adult acne is mainly clinical, but a grading tool is needed for optimizing the treatment; (2) measurement of serum androgen values (total testosterone, free testosterone, and dehydroepiandrosterone sulfate) by high-quality assays is recommended in all women with adult acne; (3) in women with adult acne and proven hyperandrogenism, oral combined estroprogestins should be added to the topical or systemic treatment of acne, independently of severity of acne; (4) all second- and third-generation estroprogestins may be used, independently of the estrogen dose and progestin component; (5) spironolactone may be added to estroprogestins in women with moderate or severe hyperandrogenic adult acne, not responding to usual treatments; (6) estroprogestins may be used in nonhyperandrogenic patients with adult acne as second-line therapy.

Impact of gut microbiome on skin health: gut-skin axis observed through the lenses of therapeutics and skin diseases

The human intestine hosts diverse microbial communities that play a significant role in maintaining gut-skin homeostasis. When the relationship between gut microbiome and the immune system is impaired, subsequent effects can be triggered on the skin, potentially promoting the development of skin diseases. The mechanisms through which the gut microbiome affects skin health are still unclear. Enhancing our understanding on the connection between skin and gut microbiome is needed to find novel ways to treat human skin disorders. In this review, we systematically evaluate current data regarding microbial ecology of healthy skin and gut, diet, pre- and probiotics, and antibiotics, on gut microbiome and their effects on skin health. We discuss potential mechanisms of the gut-skin axis and the link between the gut and skin-associated diseases, such as psoriasis, atopic dermatitis, acne vulgaris, rosacea, alopecia areata, and hidradenitis suppurativa. This review will increase our understanding of the impacts of gut microbiome on skin conditions to aid in finding new medications for skin-associated diseases.

Surfactin-oleogel with therapeutic potential for inflammatory acne vulgaris induced by Propionibacterium acnes

Accumulating evidence suggested that suppression of Propionibacterium acnes-induced inflammation was a promising strategy to alleviate acne vulgaris. This study evaluated the alleviating effect of surfactin-oleogel on P. acnes-induced inflammatory acne vulgaris in mice. Epidermis morphology and histopathological examination showed that surfactin-oleogel effectively ameliorated the P. acnes-induced epidermis swelling and erythema. Surfactin-oleogel reduced the epidermis thickness to 48.52% compared to the model control group. The colony of P. acnes in the epidermis was decreased by 1 log CFU/mL after receiving surfactin-oleogel treatment. Furthermore, surfactin-oleogel attenuated oxidative stress in the epidermis by increasing the activities of superoxide dismutase, catalase, and glutathione peroxidase. In addition, the expression of inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2, pro-inflammatory cytokines (e.g. tumour necrosis factor-α and interleukin-1β), and nuclear factor kappa-B in the epidermis were reduced after treating with surfactin-oleogel. Moreover, total cholesterol and free fatty acids were decreased, whereas the treatment of surfactin-oleogel increased triglycerides and linoleic acid content. Besides, immunohistochemical assay and real-time PCR analysis indicated that surfactin-oleogel blocked the TLR2-mediated NF-κB signalling pathways in the epidermis. Consequently, our results demonstrated that surfactin-oleogel had antibacterial and anti-inflammation activities to treat P. acnes-induced inflammatory acne vulgaris.Key points• Surfactin-oleogel effectively relieves inflammation and oxidative stress caused by P. acnes.• Surfactin-oleogel effectively reduced the P. acnes colony.• Surfactin-oleogel relieves P. acnes-induced inflammation by inactivated the TLR-mediated NF-κB.

Activation of NLRP3 Inflammasome by Palmitic Acid in Human Sebocytes

Background

Sebocytes are the main cells involved in the pathogenesis of acne by producing lipids and inflammatory cytokines. Although palmitic acid (PA) has been suggested to induce an inflammatory reaction, its effect on sebocytes remains to be elucidated.

Objective

In the present study, we investigated whether PA promotes inflammasome-mediated inflammation of sebocytes both in vivo and in vitro.

Methods

We intradermally injected PA into the mice ears. And, we treated cultured human sebocytes with PA. Inflammasome-mediated inflammation was verified by immunohistochemistry, Western blot and ELISA.

Results

PA-treated mice developed an inflammatory response associated with increased interleukin (IL)-1β expression in the sebaceous glands. When PA was added to cultured human sebocytes, caspase-1 activation and IL-1β secretion were significantly enhanced. In addition, NLRP3 knockdown attenuated IL-1β production by sebocytes stimulated with PA. PA-mediated inflammasome activation required reactive oxygen species.

Conclusion

These findings indicate that PA activates the NLRP3 inflammasome before induction of an inflammatory response in sebocytes. Thus, PA may play a role in the inflammation of acne.

Metagenomic Sequencing Analysis for Acne Using Machine Learning Methods Adapted to Single or Multiple Data

The human health status can be assessed by the means of research and analysis of the human microbiome. Acne is a common skin disease whose morbidity increases year by year. The lipids which influence acne to a large extent are studied by metagenomic methods in recent years. In this paper, machine learning methods are used to analyze metagenomic sequencing data of acne, i.e., all kinds of lipids in the face skin. Firstly, lipids data of the diseased skin (DS) samples and the healthy skin (HS) samples of acne patients and the normal control (NC) samples of healthy person are, respectively, analyzed by using principal component analysis (PCA) and kernel principal component analysis (KPCA). Then, the lipids which have main influence on each kind of sample are obtained. In addition, a multiset canonical correlation analysis (MCCA) is utilized to get lipids which can differentiate the face skins of the above three samples. The experimental results show the machine learning methods can effectively analyze metagenomic sequencing data of acne. According to the results, lipids which only influence one of the three samples or the lipids which simultaneously have different degree of influence on these three samples can be used as indicators to judge skin statuses.

Acne Syndromes and Mosaicism

Abnormal mosaicism is the coexistence of cells with at least two genotypes, by the time of birth, in an individual derived from a single zygote, which leads to a disease phenotype. Somatic mosaicism can be further categorized into segmental mosaicism and nonsegmental somatic mosaicism. Acne is a chronic illness characterized by inflammatory changes around and in the pilosebaceous units, commonly due to hormone- and inflammatory signaling-mediated factors. Several systemic disorders, such as congenital adrenal hyperplasia, polycystic ovarian syndrome, and seborrhoea-acne-hirsutism-androgenetic alopecia syndrome have classically been associated with acne. Autoinflammatory syndromes, including PAPA, PASH, PAPASH, PsAPASH, PsaPSASH, PASS, and SAPHO syndromes include acneiform lesions as a key manifestation. Mosaic germline mutations in the FGFR2 gene have been associated with Apert syndrome and nevus comedonicus, two illnesses that are accompanied by acneiform lesions. In this review, we summarize the concept of cutaneous mosaicism and elaborate on acne syndromes, as well as acneiform mosaicism.

Post-acne hyperpigmentation: Evaluation of risk factors and the use of artificial neural network as a predictive classifier

Acne is common among young individuals. People with dark skin have a higher risk for developing pigmentary complications. Inflammation is an important factor in post-acne hyperpigmentation however other factors are also involved in developing this complication however these factors are not well studied. The aim of this study is to identify risk factors involved in post-acne hyperpigmentation. Clinical data related to acne, acne- related hyperpigmentation were collected. Data was analyzed for risk factors associated with acne pigmentation. Artificial neural network was used as predictive disease classifier for the outcome of pigmentation. Majority of patients in this study (339 patients) had dark skin phototypes (3 and 4). Post- acne hyperpigmentation was seen in more than 80% of patients. Females, darker skin color, severe acne, facial sites, and excessive sunlight exposure, squeezing or scratching lesions are important risk factors for post-acne hyperpigmentation. Post-acne hyperpigmentation is multifactorial. Several factors implicated in PAH are modifiable by adequate patient education (lesion trauma, excessive sunlight exposure). The use of ANN was helpful in predicting appearance of post-acne hyperpigmentation based on identified risk factors.

Red Seaweed-Derived Compounds as a Potential New Approach for Acne Vulgaris Care

Acne vulgaris (AV) is a chronic skin disease of the pilosebaceous unit affecting both adolescents and adults. Its pathophysiology includes processes of inflammation, increased keratinization, sebum production, hormonal dysregulation, and bacterial Cutibacterium acnes proliferation. Common AV has been treated with antibiotics since the 1960s, but strain resistance has emerged and is of paramount concern. Macroalgae are known producers of substances with bioactive properties, including anti-viral, antibacterial, antioxidant, and anti-inflammatory properties, among several others. In particular, red algae are rich in bioactive compounds such as polysaccharides, phenolic compounds, lipids, sterols, alkaloids, and terpenoids, conferring them antioxidant, antimicrobial, and anti-inflammatory activities, among others. Thus, the exploration of compounds from marine resources can be an appealing approach to discover new treatment options against AV. The aim of this work is to provide an overview of the current knowledge of the potentialities of red macroalgae in the treatment of AV by reviewing the main therapeutic targets of this disease, and then the existence of compounds or extracts with bioactive properties against them.

Long-term effect of azelaic acid peel on sebum production in acne

Seborrhea and the associated oily skin are undoubtedly the problem of women and men around the world. The pathogenesis of acne vulgaris involves excessive activity of sebaceous glands, as well as disturbances in the composition of sebum. The aim of the study was to assess the severity of seborrhea in a group of acne vulgaris patients and to determine the effect of a 20% azelaic acid solution on the activity of sebaceous glands. Twenty seven women, aged 19-25 years, underwent a series of six treatments with the application of a 20% solution of azelaic acid to the face. The mean values of sebum level showed a decreasing tendency. On the forehead, the results were as follows-195.5 before the treatment and 162.7 2 weeks after the last treatment. Measurements of the right cheek decreased from 175.3 to 141.3 The measurements taken 3 months after the study were 151.3 on the forehead and 138.9 on the cheek. Similarly, the values determining the total number of acne lesions and the severity of the disease according to the IGA scale also changed significantly. Chemical peel with 20% azelaic acid shows long-term sebostatic action, which inhibits the formation of new acne lesions.

miR-146a modulates TLR1/2 and 4 induced inflammation and links it with proliferation and lipid production via the indirect regulation of GNG7 in human SZ95 sebocytes

Activation of Toll-like receptors (TLR) 1/2 and 4 are central in inducing inflammation in sebocytes by regulating the expression of protein coding mRNAs, however the microRNA (miRNA) profile in response to TLR activation and thus the possible role of miRNAs in modulating sebocyte functions has not been elucidated. In this work we identified miR-146a to have the highest induction in the TLR1/2 and 4 activated SZ95 sebocytes and found that its increased levels led to the down-regulation of IL-8 secretion, decreased the chemoattractant potential and stimulated the proliferation of sebocytes. Assessing the gene expression profile of SZ95 sebocytes treated with a miR-146a inhibitor, the induction of GNG7 was one of the highest, while when cells were treated with a miR-146a mimic, the expression of GNG7 was down-regulated. These findings correlated with our in situ hybridization results, that compared with control, miR-146a showed an increased, while GNG7 a decreased expression in sebaceous glands of acne samples. Further studies revealed, that when inhibiting the levels of GNG7 in SZ95 sebocytes, cells increased their lipid content and decreased their proliferation. Our findings suggest, that miR-146a could be a potential player in acne pathogenesis by regulating inflammation, inducing proliferation and, through the indirect down-regulation of GNG7, promoting the lipid production of sebocytes.