11β-hydroxysteroid dehydrogenase type 1 is expressed in human sebaceous glands and regulates glucocorticoid-induced lipid synthesis and toll-like receptor 2 expression in SZ95 sebocytes

Malassezia Folliculitis in the Setting of COVID-19

Purpose of Review

To review recent literature on Malassezia folliculitis and explore its association with COVID-19.

Recent Findings

Reports of Malassezia folliculitis in the setting of COVID-19 are scarce. Shared characteristics between affected individuals include male sex, obesity, intensive care, and administration of systemic antibiotics and systemic steroids. Dexamethasone can potentially stimulate sebum production and therefore lead to Malassezia proliferation. The clinical picture of Malassezia folliculitis accompanying COVID-19 is similar to classic descriptions but tends to spare the face and predominates in occlusion sites.

Summary

Malassezia folliculitis is under-recognized. Fever, sweating, occlusion, immobility, antibiotics, and dexamethasone contribute to COVID-19 patients developing Malassezia folliculitis. Antifungal therapy, together with correcting predisposing factors, is the mainstay of management. Future research should explore the relationship between systemic steroids and other acneiform reactions.

Elevated levels of cytochrome p450scc and 3β-hydroxysteroid dehydrogenase expression in skin of acne vulgaris patients

Background: Acne vulgaris belongs to androgen-dependent diseases where androgens cause sebaceous gland hypertrophy with a subsequent enlargement of sebum production. Aims: Determination of the CYP450scc 3-hydroxysteroid dehydrogenase expression profile in normal skin and skin of patients with acne. Material and methods: Immunohistochemical assay was carried out to evaluate cytochrome P450 side chain cleavage and 3-hydroxysteroid dehydrogenase expression in skin of patients with acne vulgaris and in normal skin. Results: Cytochrome P450 side chain cleavage expression was elevated in epidermal keratinocytes and sebocytes whereas 3-hydroxysteroid dehydrogenase levels were increased in mature sebocytes of acne vulgaris patients. Conclusions: The revealed alterations in expression of steroid-converting enzymes in acne skin may indicate not only the conversion of steroids produced by external steroidogenesis organs but elevated steroids local production as well. The fact may account both for sebaceous gland hyperplasia and inflammation sustenance in skin.

Prevalence and Associated Diseases of Seborrheic Skin in Adults

Background

Seborrhea is a skin condition characterized by abundant production of sebum associated with typical dermatological conditions such as rosacea and acne. Little is known about the prevalence of seborrhea and the frequency of concurrent skin diseases in the general population.

Objective

To investigate the epidemiology and comorbidity of seborrhea in the adolescent and adult working population.

Methods

In large-scale examinations by dermatologists in 343 German companies, the seborrheic skin type and the occurrence of skin findings were documented electronically. Odds ratios (OR) and their 95% confidence intervals (95% CI) of further skin diseases were computed. Logistic regression analyses were conducted for each disease using seborrhea as dependent variable.

Results

A total of 48,630 employees were examined. About 6.0% showed seborrhea (6.6% in men, 5.4% in women). Seborrhea strongly predicted acne (OR 3.59; CI 3.18-4.05), trichilemmal cysts (OR 1.99; CI 1.25-3.18) and rosacea (OR 1.45; CI 1.17-1.81). Regression analyses controlling for age, gender and phototype confirmed significant associations of seborrhea with acne and rosacea.

Conclusion

Only a minor proportion of the working population shows meaningful seborrheic skin. However, this condition predicts distinct skin diseases and thus needs attention, in particular, with respect to consulting and secondary prevention.

A randomised controlled pilot trial of oral 11β-HSD1 inhibitor AZD4017 for wound healing in adults with type 2 diabetes mellitus.. [DOI: 10.1101/2021.03.23.21254200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Chronic wounds (e.g. diabetic foot ulcers) have a major impact on quality of life, yet treatments remain limited. Glucocorticoids impair wound healing; preclinical research suggests that blocking glucocorticoid activation by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) improves wound repair. This investigator-initiated double-blind, randomised, placebo-controlled parallel-group phase 2b pilot trial investigated efficacy, safety and feasibility of 11β-HSD1 inhibition for 35 days by oral AZD4017 (AZD) treatment in adults with type 2 diabetes (n=14) compared to placebo (PCB, n=14) in a single-centre secondary care setting. Computer-generated 1:1 randomisation was pharmacy-administered. From 300 screening invitations, 36 attended, 28 were randomised. There was no proof-of-concept that AZD inhibited 24 hour skin 11β-HSD1 activity at day 28 (primary outcome: adjusted difference AZD-PCB 90% CI (diffCI)=-3.4,5.5) but systemic 11β-HSD1 activity (median urinary [THF+alloTHF]/THE ratio) was 87% lower with AZD at day 35 (PCB 1.00, AZD 0.13, diffCI=-1.04,-0.69). Mean wound gap diameter (mm) following baseline 2mm punch biopsy was 34% smaller at day 2 (PCB 1.51, AZD 0.98, diffCI=-0.95,-0.10) and 48% smaller after repeat wounding at day 30 (PCB 1.35, AZD 0.70, diffCI=-1.15,-0.16); results also suggested greater epidermal integrity but modestly impaired barrier function with AZD. AZD was well-tolerated with minimal side effects and comparable adverse events between treatments. Staff availability restricted recruitment (2.9/month); retention (27/28) and data completeness (95.3%) were excellent. These preliminary findings suggest that AZD may improve wound healing in patients with type 2 diabetes and warrant a fully-powered trial in patients with active ulcers. [Trial Registry: www.isrctn.com/ISRCTN74621291.

Funding

MRC Confidence in Concept and NIHR Senior Investigator Award.]

Single Sentence Summary

AZD4017 was safe; data suggested improved skin healing / integrity, and modestly reduced epidermal barrier function in patients with type 2 diabetes.

Disclosure Summary

I certify that neither I nor my co-authors have a conflict of interest as described above that is relevant to the subject matter or materials included in this Work.

Involvement of Pattern Recognition Receptors in the Direct Influence of Bacterial Components and Standard Antiacne Compounds on Human Sebaceous Gland Cells

INTRODUCTION

Pattern recognition receptors are involved in innate and adaptive immunity by detecting microbial components. Bacteria have been accused to play a role in inflammatory acne. We investigated the potential involvement of Toll-like receptor (TLR)2, TLR4, TLR6, and CD14 in the direct influence of bacterial components and standard antiacne compounds on human sebocytes.

METHODS

mRNA and protein expression of TLR2, TLR4, TLR6, and CD14 in SZ95 sebocytes was evaluated by real-time qRT-PCR and immunocytochemistry. The effects of lipopolysaccharides (LPS) and lipoteichoic acid on TLR2, TLR4, and CD14 expression and of cytokine/chemokine secretion by 13-cis-retinoic acid, all-trans-retinoic acid, retinol, and hydrocortisone at the mRNA and protein levels were assessed by real-time qRT-PCR and ELISA and verified by cocultivation with neutralizing antibodies.

RESULTS

The constitutive expression of TLR2, TLR4, and CD14 in SZ95 sebocytes was augmented by exposure to LPS. Hydrocortisone induced TLR2, but markedly reduced TLR4 expression. 13-cis-retinoic acid and all-trans-retinoic acid regulated IL-6 release. LPS enhanced and hydrocortisone reduced cytokine and chemokine release. Anti-TLR4 and anti-CD14 mAb blocked LPS-induced IL-8 and IL-6 release.

CONCLUSIONS

Microbial components use pattern recognition receptors to directly activate sebocytes to express a wide range of proinflammatory molecules and especially IL-8 and IL-6 in a TLR4- and CD14-specific manner. Retinoids, but mostly corticosteroids, also use this pathway to exhibit anti-inflammatory effects.

Genome wide analysis of TLR1/2- and TLR4-activated SZ95 sebocytes reveals a complex immune-competence and identifies serum amyloid A as a marker for activated sebaceous glands

Toll-like receptors (TLR) 2 and 4 are active in sebaceous glands and play a central role in the development of acne. Still, there is only limited knowledge on their effect on sebocytes. In this work we performed global gene expression profile analysis with functional clustering of the differentially regulated genes of TLR1/2 (PAM3CSK4)- and TLR4 (lipopolysaccharide [LPS])-activated SZ95 sebocytes. Both TLR1/2- and 4-activation promoted inflammation in a similar manner already at an early time-point (6 hours), regulating genes involved in inflammation, wound healing and chemotaxis reflecting a more complex cytokine and chemokine regulation than previously known. Importantly, lipid metabolism, the primary feature of sebocytes, was affected at the level of gene expression only at a later time point (24 hours) indicating that sebocytes prioritize to exert a pro-inflammatory phenotype when confronted with a danger signal. Supporting the biological relevance of our results, a meta-analysis revealed that the genes showing the strongest up-regulation were also found up-regulated in acne. Of these genes, serum amyloid A 1/2 (SAA1/2) was confirmed to be a suitable protein marker for in vivo activated sebocytes, underlining their immune-competence, which is structurally defined within sebaceous glands of acne and rosacea skin samples. Altogether our findings demonstrate that sebocytes are not only positioned at the end point of inflammation but are actively involved in shaping the inflammatory response with putative diagnostic and therapeutic relevance.

Psychological Stress Deteriorates Skin Barrier Function by Activating 11β-Hydroxysteroid Dehydrogenase 1 and the HPA Axis

Psychological stress (PS) increases endogenous glucocorticoids (GC) by activating the hypothalamic-pituitary-adrenal axis. The negative effects of GC on skin barrier function under PS have been well-established. However, endogenous GC can also be active when cortisone (inactive form) is converted to cortisol (active form) by 11β-hydroxysteroid dehydrogenase type I (11ß-HSD1) in the peripheral tissue. Here, we evaluated the changes in 11ß-HSD1 and barrier function under PS. Elevated 11ß-HSD1 in oral mucosa correlated with increased cortisol in the stratum corneum and deteriorated barrier function. Expression of 11ß-HSD1 in the oral mucosa correlated with that in the epidermal keratinocytes. We further investigated whether barrier function improved when PS was relieved using a selective serotonin reuptake inhibitor (SSRI) in patients with anxiety. Decreased 11ß-HSD1 and improved barrier function were observed after SSRI treatment. The collective findings suggest that elevated 11ß-HSD1 under PS increases the level of cutaneous GC and eventually impairs barrier function. PS-alleviating drugs, such as SSRI, may help to treat PS-aggravated skin diseases.

Sebum lipids influence macrophage polarization and activation

BACKGROUND

As lipids are known to regulate macrophage functions, it is reasonable to suppose that a sebocyte-macrophage axis mediated by sebum lipids may exist.

OBJECTIVES

To investigate if sebocytes could contribute to the differentiation, polarization and function of macrophages with their secreted lipids.

METHODS

Oil Red O lipid staining and Raman spectroscopy were used to assess the dermal lipid content and penetration. Immunohistochemistry was used to analyse the macrophage subsets. Human peripheral blood monocytes were differentiated in the presence of either supernatant from human SZ95 sebocytes or major sebum lipid components and activated with Propionibacterium acnes. Macrophage surface markers and their capacity to uptake fluorescein isothiocyanate-conjugated P. acnes were detected by fluorescence-activated cell sorting measurements. Cytokine protein levels were evaluated by enzyme-linked immunosorbent assay and Western blot analysis.

RESULTS

Sebaceous gland-rich skin had an increased dermal lipid content vs. sebaceous gland-poor skin to which all the tested sebum component lipids could contribute by penetrating the dermoepidermal barrier. Of the lipids, oleic acid and linoleic acid promoted monocyte differentiation into alternatively activated macrophages. Moreover, linoleic acid also had an anti-inflammatory effect in P. acnes-activated macrophages, inhibiting the secretion of interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α. Squalene, palmitic acid, stearic acid and oleic acid augmented the secretion of IL-1β, even in the absence of P. acnes, whereas oleic acid had a selective effect of inducing IL-1β but downregulating IL-6 and TNF-α secretion.

CONCLUSIONS

Our results suggest a role for sebaceous glands in modulating innate immune responses via their secreted lipids that are of possible pathological and therapeutic relevance.

11β-Hydroxysteroid Dehydrogenase Type 1 Inhibition Attenuates the Adverse Effects of Glucocorticoids on Dermal Papilla Cells

PURPOSE

Glucocorticoids, stress-related hormones, inhibit hair growth. Intracellular glucocorticoid availability is regulated by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). 11β-HSD1 was recently detected in keratinocytes and fibroblasts. However, the expression of 11β-HSD1 in human hair follicles remains unknown. We aimed to examine 11β-HSD1 expression in human dermal papilla cells (DPCs) and to investigate whether modulation of 11β-HSD1 activity can regulate the negative effects of glucocorticoids on DPCs.

MATERIALS AND METHODS

11β-HSD1 expression in normal human scalp skin was examined by immunohistochemistry. 11β-HSD1 protein was detected in Western blots of human DPCs. Cultured human DPCs were treated with cortisol with or without a selective 11β-HSD1 inhibitor and subsequently stained for Ki-67 antibody. Expression levels of 11β-HSD1, Wnt5a, alkaline phosphatase (ALP), and vascular endothelial growth factor (VEGF) were analyzed by Western blotting.

RESULTS

11β-HSD1 was detected in dermal papilla in human scalp skin by immunohistochemistry. Human DPCs expressed 11β-HSD1 protein in vitro. Furthermore, cortisol stimulated the expression of 11β-HSD1 in DPCs. Glucocorticoids decreased cellular proliferation and the expression of Wnt5a, ALP, and VEGF in DPCs. A specific 11β-HSD1 inhibitor significantly attenuated the anti-proliferative effects of cortisol and reversed the cortisol-induced suppression of Wnt5a, ALP, and VEGF expression in DPCs.

CONCLUSION

Our data demonstrated the expression of 11β-HSD1 in human DPCs and revealed that inhibition of 11β-HSD1 activity can partially prevent the negative effect of glucocorticoids on DPCs, suggesting the possible application of 11β-HSD1 inhibitors for stress-related hair loss.

Characterisation of the cancer-associated glucocorticoid system: key role of 11β-hydroxysteroid dehydrogenase type 2

Background:

Recent studies have shown that production of cortisol not only takes place in several non-adrenal peripheral tissues such as epithelial cells but, also, the local inter-conversion between cortisone and cortisol is regulated by the 11β-hydroxysteroid dehydrogenases (11β-HSDs). However, little is known about the activity of this non-adrenal glucocorticoid system in cancers.

Methods:

The presence of a functioning glucocorticoid system was assessed in human skin squamous cell carcinoma (SCC) and melanoma and further, in 16 epithelial cell lines from 8 different tissue types using ELISA, western blotting and immunofluorescence. 11β-HSD2 was inhibited both pharmacologically and by siRNA technology. Naïve CD8⁺ T cells were used to test the paracrine effects of cancer-derived cortisol on the immune system in vitro. Functional assays included cell–cell adhesion and cohesion in two- and three-dimensional models. Immunohistochemical data of 11β-HSD expression were generated using tissue microarrays of 40 cases of human SCCs as well as a database featuring 315 cancer cases from 15 different tissues.

Results:

We show that cortisol production is a common feature of malignant cells and has paracrine functions. Cortisol production correlated with the magnitude of glucocorticoid receptor (GR)-dependent inhibition of tumour-specific CD8⁺ T cells in vitro. 11β-HSDs were detectable in human skin SCCs and melanoma. Analyses of publicly available protein expression data of 11β-HSDs demonstrated that 11β-HSD1 and -HSD2 were dysregulated in the majority (73%) of malignancies. Pharmacological manipulation of 11β-HSD2 activity by 18β-glycyrrhetinic acid (GA) and silencing by specific siRNAs modulated the bioavailability of cortisol. Cortisol also acted in an autocrine manner and promoted cell invasion in vitro and cell–cell adhesion and cohesion in two- and three-dimensional models. Immunohistochemical analyses using tissue microarrays showed that expression of 11β-HSD2 was significantly reduced in human SCCs of the skin.

Conclusions:

The results demonstrate evidence of a cancer-associated glucocorticoid system and show for the first time, the functional significance of cancer-derived cortisol in tumour progression.

Polyphenol-rich apple extract inhibits dexamethasone-induced sebaceous lipids production by regulating SREBP1 expression

Sebum production and excretion is a primary function of the sebaceous glands, but abnormally increased sebum production is a major cause of acne vulgaris. To identify a new candidate that regulates sebum production, we investigated the possible inhibitory effects of apple polyphenols (APP) purified from unripe apples on primary cultured human sebocytes and in patients with acne vulgaris. Dexamethasone (Dex) increased lipid synthesis and expression of the sterol response element-binding protein 1 (SREBP 1) and its target enzymes, acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), in the sebocytes. However, APP inhibited Dex-induced lipid production and expression of SREBP-1, ACC and FAS. APP also inhibited the increase in the expression and activation of glucocorticoid receptor in the sebocytes. Taken together, these results suggest that APP may be useful to regulate sebum production and may alleviate sebum-involved skin disease, such as acne vulgaris.

Recognition of Propionibacterium acnes by human TLR2 heterodimers

Propionibacterium acnes has been considered as a crucial contributor to the pathogenesis of acne vulgaris. The interaction between P. acnes and the host is mainly mediated by Toll like receptor (TLR) 2 recognition. TLR2 homodimers recognize P. acnes in mice, but here we describe the prerequisite of TLR2/1 and TLR2/6 heterodimers in human cells for P. acnes recognition. P. acnes-induced NF-κB and AP-1activation observed in HEK hTLR2-transfected but not control cells confirmed the specificity of TLR2 recognition. The activation was blocked by neutralizing antibodies against TLR2, TLR1 and TLR6, as well as the TLR2 antagonist CU-CPT22, which showed no selectivity towards human TLR2 heterodimers. The combination of anti-TLR1 and anti-TLR6 antibodies completely abrogated activation by P. acnes. In primary human keratinocytes, P. acnes-increased NF-κB phosphorylation was inhibited by anti-TLR6 and anti-TLR2 antibodies. Furthermore, P. acnes-induced inflammatory responses were impaired by anti-TLR2 neutralizing antibodies and fully blocked by CU-CPT22. Our study suggests species-specific recognition of P. acnes by TLR2 heterodimers which can be exploited therapeutically by small molecules targeting TLR2 for the control of inflammatory responses.

What's new in the physiopathology of acne?

There are four central factors that contribute to acne physiopathology: the inflammatory response, colonization with Propionibacterium acnes, increased sebum production and hypercornification of the pilosebaceous duct. In addition, research in the areas of diet and nutrition, genetics and oxidative stress is also yielding some interesting insights into the development of acne. In this paper we review some of the most recent research and novel concepts revealed in this work, which has been published by researchers from diverse academic disciplines including dermatology, immunology, microbiology and endocrinology. We discuss the implications of their findings (particularly in terms of opportunities to develop new therapies), highlight interrelationships between these novel factors that could contribute to the pathology of acne, and indicate where gaps in our understanding still exist.

Acne vulgaris

Acne vulgaris is a chronic inflammatory disease - rather than a natural part of the life cycle as colloquially viewed - of the pilosebaceous unit (comprising the hair follicle, hair shaft and sebaceous gland) and is among the most common dermatological conditions worldwide. Some of the key mechanisms involved in the development of acne include disturbed sebaceous gland activity associated with hyperseborrhoea (that is, increased sebum production) and alterations in sebum fatty acid composition, dysregulation of the hormone microenvironment, interaction with neuropeptides, follicular hyperkeratinization, induction of inflammation and dysfunction of the innate and adaptive immunity. Grading of acne involves lesion counting and photographic methods. However, there is a lack of consensus on the exact grading criteria, which hampers the conduction and comparison of randomized controlled clinical trials evaluating treatments. Prevention of acne relies on the successful management of modifiable risk factors, such as underlying systemic diseases and lifestyle factors. Several treatments are available, but guidelines suffer from a lack of data to make evidence-based recommendations. In addition, the complex combination treatment regimens required to target different aspects of acne pathophysiology lead to poor adherence, which undermines treatment success. Acne commonly causes scarring and reduces the quality of life of patients. New treatment options with a shift towards targeting the early processes involved in acne development instead of suppressing the effects of end products will enhance our ability to improve the outcomes for patients with acne.

Skin and glucocorticoids: effects of local skin glucocorticoid impairment on skin homeostasis

The role of skin as a de novo source of glucocorticoids and the importance of cutaneous glucocorticoidogenesis as a homeostatic mechanism in human skin is highlighted by Slominski et al. in a recently published issue. Impairment of glucocorticoidogenesis through noxious stimuli, such as UVB, can explain pathophysiology of skin diseases (e.g. rosacea). In addition to keratinocytes, melanocytes and fibroblasts, cutaneous adnexes also play a significant role as targets and sources of glucocorticoids, because they express most of the enzymes required for steroidogenesis. Glucocorticoids are also involved in the pathogenesis of acne lesions, affecting sebum production in vivo and in vitro. Certain steroidogenic enzymes, such as 11β-hydroxysteroid dehydrogenase, are upregulated in acne lesions. On this background, the paper by Slominski et al. provides further insights into dermatoendocrinology, with emphasis on the importance of an impairment of the skin's own hypothalamic-pituitary-adrenal-like axis in the pathophysiology of several skin diseases.

Leptin promotes a proinflammatory lipid profile and induces inflammatory pathways in human SZ95 sebocytes

BACKGROUND

Leptin, the adipocyte-secreted hormone that regulates weight, is known to link lipid metabolism with inflammation in various cell types. However, its role in human sebocytes has not yet been investigated.

OBJECTIVES

The purpose of this study was to investigate the effects of leptin in human sebaceous gland biology.

METHODS

Expression of the long form of the leptin receptor (Ob-Rb) was detected by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and immunochemistry. Lipid analysis was by high-performance thin-layer chromatography, gas chromatography-mass spectrometry and time-of-flight mass spectrometer mass detection. Lipid bodies were visualized by BODIPY staining using fluorescent microscopy and measured by flow cytometry. Interleukin (IL)-6 and IL-8 mRNA levels were assessed by real-time qRT-PCR and their release was evaluated by enzyme-linked immunosorbent assay. Cyclooxygenase (COX)-2 and 5-lipooxygenase (LOX) protein expression and phosphorylation of p65 and signal transducer and activator of transcription (STAT)-3 were determined by Western blot analysis.

RESULTS

Expression of Ob-Rb was detected in human sebaceous glands and in cultured human SZ95 sebocytes. The treatment of SZ95 sebocytes with leptin led to enlarged intracellular lipid bodies, increased ratios of unsaturated/saturated fatty acids and decreased vitamin E levels. Further supporting a proinflammatory role, leptin induced COX-2 and 5-LOX expression in SZ95 sebocytes and augmented the production of IL-6 and IL-8 cytokines. On leptin treatment, the STAT-3 and nuclear factor-κB pathways were activated, indicating that these known leptin signalling pathways are active in human sebocytes.

CONCLUSIONS

Our findings suggest that leptin signalling may be involved in the proinflammatory regulation of sebaceous lipid metabolism and the induction of inflammatory enzymes and cytokines.

Steroidogenesis in the skin: implications for local immune functions

The skin has developed a hierarchy of systems that encompasses the skin immune and local steroidogenic activities in order to protect the body against the external environment and biological factors and to maintain local homeostasis. Most recently it has been established that skin cells contain the entire biochemical apparatus necessary for production of glucocorticoids, androgens and estrogens either from precursors of systemic origin or, alternatively, through the conversion of cholesterol to pregnenolone and its subsequent transformation to biologically active steroids. Examples of these products are corticosterone, cortisol, testosterone, dihydrotesterone and estradiol. Their local production can be regulated by locally produced corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) or cytokines. Furthermore the production of glucocorticoids is affected by ultraviolet B radiation. The level of production and nature of the final steroid products are dependent on the cell type or cutaneous compartment, e.g., epidermis, dermis, adnexal structures or adipose tissue. Locally produced glucocorticoids, androgens and estrogens affect functions of the epidermis and adnexal structures as well as local immune activity. Malfunction of these steroidogenic activities can lead to inflammatory disorders or autoimmune diseases. The cutaneous steroidogenic system can also have systemic effects, which are emphasized by significant skin contribution to circulating androgens and/or estrogens. Furthermore, local activity of CYP11A1 can produce novel 7Δ-steroids and secosteroids that are biologically active. Therefore, modulation of local steroidogenic activity may serve as a new therapeutic approach for treatment of inflammatory disorders, autoimmune processes or other skin disorders. In conclusion, the skin can be defined as an independent steroidogenic organ, whose activity can affect its functions and the development of local or systemic inflammatory or autoimmune diseases. This article is part of a Special Issue entitled 'CSR 2013'.