Human sebaceous glands engage in aerobic glycolysis and glutaminolysis

Acne Transcriptomics: Fundamentals of Acne Pathogenesis and Isotretinoin Treatment

This review on acne transcriptomics allows for deeper insights into the pathogenesis of acne and isotretinoin's mode of action. Puberty-induced insulin-like growth factor 1 (IGF-1), insulin and androgen signaling activate the kinase AKT and mechanistic target of rapamycin complex 1 (mTORC1). A Western diet (hyperglycemic carbohydrates and milk/dairy products) also co-stimulates AKT/mTORC1 signaling. The AKT-mediated phosphorylation of nuclear FoxO1 and FoxO3 results in their extrusion into the cytoplasm, a critical switch which enhances the transactivation of lipogenic and proinflammatory transcription factors, including androgen receptor (AR), sterol regulatory element-binding transcription factor 1 (SREBF1), peroxisome proliferator-activated receptor γ (PPARγ) and signal transducer and activator of transcription 3 (STAT3), but reduces the FoxO1-dependent expression of GATA binding protein 6 (GATA6), the key transcription factor for infundibular keratinocyte homeostasis. The AKT-mediated phosphorylation of the p53-binding protein MDM2 promotes the degradation of p53. In contrast, isotretinoin enhances the expression of p53, FoxO1 and FoxO3 in the sebaceous glands of acne patients. The overexpression of these proapoptotic transcription factors explains isotretinoin's desirable sebum-suppressive effect via the induction of sebocyte apoptosis and the depletion of BLIMP1(+) sebocyte progenitor cells; it also explains its adverse effects, including teratogenicity (neural crest cell apoptosis), a reduced ovarian reserve (granulosa cell apoptosis), the risk of depression (the apoptosis of hypothalamic neurons), VLDL hyperlipidemia, intracranial hypertension and dry skin.

Antibiotic-producing Micrococcales govern the microbiome that inhabits the fur of two- and three-toed sloths

Sloths have a dense coat on which insects, algae, and fungi coexist in a symbiotic relationship. This complex ecosystem requires different levels of control, however, most of these mechanisms remain unknown. We investigated the bacterial communities inhabiting the hair of two- (Choloepus Hoffmani) and three-toed (Bradypus variegatus) sloths and evaluated their potential for producing antibiotic molecules capable of exerting control over the hair microbiota. The analysis of 16S rRNA amplicon sequence variants (ASVs) revealed that the communities in both host species are dominated by Actinobacteriota and Firmicutes. The most abundant genera were Brevibacterium, Kocuria/Rothia, Staphylococcus, Rubrobacter, Nesterenkonia, and Janibacter. Furthermore, we isolated nine strains of Brevibacterium and Rothia capable of producing substances that inhibited the growth of common mammalian pathogens. The analysis of the biosynthetic gene clusters (BCGs) of these nine isolates suggests that the pathogen-inhibitory activity could be mediated by the presence of siderophores, terpenes, beta-lactones, Type III polyketide synthases (T3PKS), ribosomally synthesized, and post-translationally modified peptides (RiPPs), non-alpha poly-amino acids (NAPAA) like e-Polylysin, ectoine or nonribosomal peptides (NRPs). Our data suggest that Micrococcales that inhabit sloth hair could have a role in controlling microbial populations in that habitat, improving our understanding of this highly complex ecosystem. This article is protected by copyright. All rights reserved.

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.

Culture of the human pilosebaceous unit, hair follicle and sebaceous gland

Terence Kealey first pioneered the isolation and organ maintenance of human eccrine and sebaceous glands in the early to mid-1980. This led to subsequent methods describing the isolation and culture of human hair follicles, the human pilosebaceous unit as well as the sebaceous duct. The importance of these models in the study of the biology of human skin glands and appendages has been demonstrated in numerous publications and their importance as models for animal replacement, refinement and reduction (3Rs) is increasingly important. In particular, in vitro (ex vivo) hair follicle culture has played a significant part in helping elucidate the role of signalling molecules in regulating hair growth and hair fibre formation and has been especially useful in understanding metabolic aspects of hair growth. However, obtaining sufficient numbers of hair follicles is becoming increasingly difficult as plastic surgery becomes less invasive and smaller skin samples provided. There is therefore an urgent requirement for the next generation of in vitro models using cell lines and tissue engineering, and this has led to the development of immortalised cell lines as well as attempts to model hair follicle embryogenesis in vitro and development of skin on a chip.

Acne and Rosacea

Acne, one of the most common skin diseases, affects approximately 85% of the adolescent population, and occurs most prominently at skin sites with a high density of sebaceous glands such as the face, back, and chest. Although often considered a disease of teenagers, acne is occurring at an increasingly early age. Rosacea is a chronic facial inflammatory dermatosis characterized by flushing (or transient facial erythema), persistent central facial erythema, inflammatory papules/pustules, and telangiectasia. Both acne and rosacea have a multifactorial pathology that is incompletely understood. Increased sebum production, keratinocyte hyper-proliferation, inflammation, and altered bacterial colonization with Propionibacterium acnes are considered to be the underlying disease mechanisms in acne, while the multifactorial pathology of rosacea is thought to involve both vasoactive and neurocutaneous mechanisms. Several advances have taken place in the past decade in the research field of acne and rosacea, encompassing pathogenesis and epidemiology, as well as the development of new therapeutic interventions. In this article, we provide an overview of current perspectives on the pathogenesis and treatment of acne and rosacea, including a summary of findings from recent landmark pathophysiology studies considered to have important implications for future clinical practice. The advancement of our knowledge of the different pathways and regulatory mechanisms underlying acne and rosacea is thought to lead to further advances in the therapeutic pipeline for both conditions, ultimately providing a greater array of treatments to address gaps in current management practices.

Linking diet to acne metabolomics, inflammation, and comedogenesis: an update

Acne vulgaris, an epidemic inflammatory skin disease of adolescence, is closely related to Western diet. Three major food classes that promote acne are: 1) hyperglycemic carbohydrates, 2) milk and dairy products, 3) saturated fats including trans-fats and deficient ω-3 polyunsaturated fatty acids (PUFAs). Diet-induced insulin/insulin-like growth factor (IGF-1)-signaling is superimposed on elevated IGF-1 levels during puberty, thereby unmasking the impact of aberrant nutrigenomics on sebaceous gland homeostasis. Western diet provides abundant branched-chain amino acids (BCAAs), glutamine, and palmitic acid. Insulin and IGF-1 suppress the activity of the metabolic transcription factor forkhead box O1 (FoxO1). Insulin, IGF-1, BCAAs, glutamine, and palmitate activate the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the key regulator of anabolism and lipogenesis. FoxO1 is a negative coregulator of androgen receptor, peroxisome proliferator-activated receptor-γ (PPARγ), liver X receptor-α, and sterol response element binding protein-1c (SREBP-1c), crucial transcription factors of sebaceous lipogenesis. mTORC1 stimulates the expression of PPARγ and SREBP-1c, promoting sebum production. SREBP-1c upregulates stearoyl-CoA- and Δ6-desaturase, enhancing the proportion of monounsaturated fatty acids in sebum triglycerides. Diet-mediated aberrations in sebum quantity (hyperseborrhea) and composition (dysseborrhea) promote Propionibacterium acnes overgrowth and biofilm formation with overexpression of the virulence factor triglyceride lipase increasing follicular levels of free palmitate and oleate. Free palmitate functions as a "danger signal," stimulating toll-like receptor-2-mediated inflammasome activation with interleukin-1β release, Th17 differentiation, and interleukin-17-mediated keratinocyte proliferation. Oleate stimulates P. acnes adhesion, keratinocyte proliferation, and comedogenesis via interleukin-1α release. Thus, diet-induced metabolomic alterations promote the visible sebofollicular inflammasomopathy acne vulgaris. Nutrition therapy of acne has to increase FoxO1 and to attenuate mTORC1/SREBP-1c signaling. Patients should balance total calorie uptake and restrict refined carbohydrates, milk, dairy protein supplements, saturated fats, and trans-fats. A paleolithic-like diet enriched in vegetables and fish is recommended. Plant-derived mTORC1 inhibitors and ω-3-PUFAs are promising dietary supplements supporting nutrition therapy of acne vulgaris.

Acne e dieta: verdade ou mito?

Nos últimos 50 anos, foram publicados inúmeros estudos com a finalidade de comprovar se a dieta está relacionada à etiologia da acne. Embora existam estudos antigos, que são bem difundidos entre os dermatologistas e negam a associação entre acne e dieta, seu delineamento científico é pobre. Recentemente, novos artigos demonstraram evidências contrárias às publicações anteriores. Sendo assim, os autores realizaram esta revisão bibliográfica com o intuito de averiguar se a dieta influencia direta ou indiretamente um ou mais dos quatro pilares etiopatogênicos fundamentais da acne: (1) hiperproliferação dos queratinócitos basais, (2) aumento da produção sebácea, (3) colonização pelo Propionibacterium acnes e (4) inflamação.

The effect of a low glycemic load diet on acne vulgaris and the fatty acid composition of skin surface triglycerides

BACKGROUND

Dietary factors have long been implicated in acne pathogenesis. It has recently been hypothesized that low glycemic load diets may influence sebum production based on the beneficial endocrine effects of these diets.

OBJECTIVE

To determine the effect of a low glycemic load diet on acne and the fatty acid composition of skin surface triglycerides.

METHODS

Thirty-one male acne patients (aged 15-25 years) completed sebum sampling tests as part of a larger 12-week, parallel design dietary intervention trial. The experimental treatment was a low glycemic load diet, comprised of 25% energy from protein and 45% from low glycemic index carbohydrates. In contrast, the control situation emphasized carbohydrate-dense foods without reference to the glycemic index. Acne lesion counts were assessed during monthly visits. At baseline and 12-weeks, the follicular sebum outflow and composition of skin surface triglycerides were assessed using lipid absorbent tapes.

RESULTS

At 12 weeks, subjects on the experimental diet demonstrated increases in the ratio of saturated to monounsaturated fatty acids of skin surface triglycerides when compared to controls [5.3+/-2.0% (mean+/-S.E.M.) vs. -2.7+/-1.7%, P=0.007]. The increase in the saturated/monounsaturated ratio correlated with acne lesion counts(r=-0.39, P=0.03). Increased follicular sebum outflow was also associated with an increase in the proportion of monounsaturated fatty acids in sebum (r=0.49, P=0.006).

CONCLUSION

This suggests a possible role of desaturase enzymes in sebaceous lipogenesis and the clinical manifestation of acne. However, further work is needed to clarify the underlying role of diet in sebum gland physiology.