Human Skin Diseases Research Articles

Short-Chain Fatty Acids from Cutibacterium acnes Activate Both a Canonical and Epigenetic Inflammatory Response in Human Sebocytes.

The regulation of cutaneous inflammatory processes is essential for the human skin to maintain homeostasis in the presence of the dense communities of resident microbes that normally populate this organ. Forming the hair follicle-associated sebaceous gland, sebocytes are specialized lipid-producing cells that can release inflammatory mediators. Cytokine and chemokine expression by pilosebaceous epithelial cells (i.e., sebocytes and follicular keratinocytes) has been proposed to contribute to the common human skin disease acne vulgaris. The underlying mechanisms that drive inflammatory gene expression in acne-involved pilosebaceous epithelial cells are still unknown because almost all sebaceous follicles contain dense concentrations of bacteria yet only some show an inflammatory reaction. In this study, we hypothesized that metabolites from the abundant skin-resident microbe Propionibacterium acnes can influence cytokine expression from human sebocytes. We show that short-chain fatty acids produced by P. acnes under environmental conditions that favor fermentation will drive inflammatory gene expression from sebocytes. These molecules are shown to influence sebocyte behavior through two distinct mechanisms: the inhibition of histone deacetylase (HDAC) activity and the activation of fatty acid receptors. Depletion of HDAC8 and HDAC9 in human sebocytes resulted in an enhanced cytokine response to TLR-2 activation that resembled the transcriptional profile of an acne lesion. These data provide a new insight into the regulation of inflammatory gene expression in the skin, further characterize the contribution of sebocytes to epidermal immunity, and demonstrate how changes in the metabolic state of the skin microbiome can promote inflammatory acne.

Defining Key Genes Regulating Morphogenesis of Apocrine Sweat Gland in Sheepskin.

The apocrine sweat gland is a unique skin appendage in humans compared to mouse and chicken models. The absence of apocrine sweat glands in chicken and murine skin largely restrains further understanding of the complexity of human skin biology and skin diseases, like hircismus. Sheep may serve as an additional system for skin appendage investigation owing to the distributions and histological similarities between the apocrine sweat glands of sheep trunk skin and human armpit skin. To understand the molecular mechanisms underlying morphogenesis of apocrine sweat glands in sheepskin, transcriptome analyses were conducted to reveal 1631 differentially expressed genes that were mainly enriched in three functional groups (cellular component, molecular function and biological process), particularly in gland, epithelial, hair follicle and skin development. There were 7 Gene Ontology (GO) terms enriched in epithelial cell migration and morphogenesis of branching epithelium that were potentially correlated with the wool follicle peg elongation. An additional 5 GO terms were enriched in gland morphogenesis (20 genes), gland development (42 genes), salivary gland morphogenesis and development (8 genes), branching involved in salivary gland morphogenesis (6 genes) and mammary gland epithelial cell differentiation (4 genes). The enriched gland-related genes and two Kyoto Encyclopedia of Genes and Genomes pathway genes (WNT and TGF-β) were potentially involved in the induction of apocrine sweat glands. Genes named BMPR1A, BMP7, SMAD4, TGFB3, WIF1, and WNT10B were selected to validate transcript expression by qRT-PCR. Immunohistochemistry was performed to localize markers for hair follicle (SOX2), skin fibroblast (PDGFRB), stem cells (SOX9) and BMP signaling (SMAD5) in sheepskin. SOX2 and PDGFRB were absent in apocrine sweat glands. SOX9 and SMAD5 were both observed in precursor cells of apocrine sweat glands and later in gland ducts. These results combined with the upregulation of BMP signaling genes indicate that apocrine sweat glands were originated from outer root sheath of primary wool follicle and positively regulated by BMP signaling. This report established the primary network regulating early development of apocrine sweat glands in sheepskin and will facilitate the further understanding of histology and pathology of apocrine sweat glands in human and companion animal skin.

Skin Inflammation in Human Health and Disease: 2018 International Conference

From June 28-30, 2018, a course entitled "Skin Inflammation in Human Health and Disease: 2018 International Conference" was held in Boston, Massachusetts. In attendance were 107 physicians and scientists from 12 countries. This course was organized by Drs. Rachael Clark, John O'Malley, and Hans Widlund of the Brigham and Women's Hospital, Human Skin Disease Resource Center, Harvard Medical School (Boston, MA). The key findings reported at the meeting are summarized here.

Anti-Malassezia furfur activity of Several Medicinal Herb

Background, Objectives: Malassezia furfur is a yeast that causes skin diseases in humans and causes inconvenience to humans. This study is about anti-malassezia furfur effects and antioxidant effects of medicinal plants. Methods, Statistical analysis: Medicinal plant ethanol extracts were examined by disc diffusion method for anti-Malassezia furfur activity and used fluconazol(50mg/ml), 99% Ethanol as a positive controls. We measured the area of clear zone and evaluated that the larger size of the area was more effectives against Malassezia furfur. Findings: The result of this study, Cinnamomum cassia Blume value was highest as 32mm and next Rhus javanica L. 25mm. This result is a result which is equivalent to about 62% when compared to 52mm of the Fluconazol (50mg / ml) positive control. Improvements/Applications: when they are used for soap, shampoo, body wash applied to skin by combination of them, It is thought to be an excellent natural antimicrobial material that prevents skin disease.

Perivascular Adventitial Fibroblast Specialization Accompanies T Cell Retention in the Inflamed Human Dermis.

Perivascular accumulation of lymphocytes can be a prominent histopathologic feature of various human inflammatory skin diseases. Select examples include systemic sclerosis, spongiotic dermatitis, and cutaneous lupus. Although a large body of work has described various aspects of the endothelial and vascular smooth muscle layers in these diseases, the outer adventitial compartment is poorly explored. The goal of the current study was to characterize perivascular adventitial fibroblast states in inflammatory human skin diseases and relate these states to perivascular lymphocyte accumulation. In normal skin, adventitial fibroblasts are distinguished by CD90 expression, and dense perivascular lymphocytic infiltrates are uncommon. In systemic sclerosis, this compartment expands, but lymphocyte infiltrates remain sparse. In contrast, perivascular adventitial fibroblast expression of VCAM1 is upregulated in spongiotic dermatitis and lupus and is associated with a dense perivascular T cell infiltrate. VCAM1 expression marks transitioned fibroblasts that show some resemblance to the reticular stromal cells in secondary lymphoid organs. Expanded adventitial compartments with perivascular infiltrates similar to the human settings were not seen in the inflamed murine dermis. This species difference may hinder the dissection of aspects of perivascular adventitial pathology. The altered perivascular adventitial compartment and its associated reticular network form a niche for lymphocytes and appear to be fundamental in the development of an inflammatory pattern.

Propionibacterium (Cutibacterium) acnes Bacteriophage Therapy in Acne: Current Evidence and Future Perspectives.

Acne vulgaris is the most common dermatological disorder worldwide. It is a multifactorial disease that involves increased sebum production, hyperkeratinization of the pilosebaceous unit, Propionibacterium acnes (Cutibacterium acnes) colonization, and inflammation. The human skin microbiome hosts a wide variety of microorganisms, including bacteria, viruses, and fungi. A delicate balance of these microorganisms is essential for the barrier function of the skin. Propionibacterium acnes represents nearly 90% of the human skin microbiome of healthy adults. Acne is a chronic recurrent disease that requires long-lasting treatment, which has led to the emergence of antibiotic resistance. New alternatives to traditional therapy are emerging, including antimicrobial peptides, natural engineered antibodies, and bacteriophages. Bacteriophages have been shown to play a role in human skin health and disease. There is evidence supporting phage therapy in many types of skin infections. P. acnes bacteriophages have been isolated and characterized. However, only a few in vitro studies have tested the ability of bacteriophages to kill P. acnes. Furthermore, there is no evidence on bacteriophage therapy in the treatment of acne in humans. In this review, we summarize the most recent evidence regarding P. acnes bacteriophages and the potential role of these bacteriophages in the treatment of acne. Further research on this field will provide the evidence to use phage therapy to decrease rates of antibiotic resistance and restore antibiotic susceptibility of P. acnes.

Development of an innervated tissue-engineered skin with human sensory neurons and Schwann cells differentiated from iPS cells

Cutaneous innervation is increasingly recognized as a major element of skin physiopathology through the neurogenic inflammation driven by neuropeptides that are sensed by endothelial cells and the immune system. To investigate this process in vitro, models of innervated tissue-engineered skin (TES) were developed, yet exclusively with murine sensory neurons extracted from dorsal root ganglions. In order to build a fully human model of innervated TES, we used induced pluripotent stem cells (iPSC) generated from human skin fibroblasts. Nearly 100% of the iPSC differentiated into sensory neurons were shown to express the neuronal markers BRN3A and β3-tubulin after 19 days of maturation. In addition, these cells were also positive to TRPV1 and neurofilament M, and some of them expressed Substance P, TrkA and TRPA1. When stimulated with molecules inducing neuropeptide release, iPSC-derived neurons released Substance P and CGRP, both in conventional monolayer culture and after seeding in a 3D fibroblast-populated collagen sponge model. Schwann cells, the essential partners of neurons for function and axonal migration, were also successfully differentiated from human iPSC as shown by their expression of the markers S100, GFAP, p75 and SOX10. When cultured for one additional month in the TES model, iPSC-derived neurons seeded at the bottom of the sponge formed a network of neurites spanning the whole TES up to the epidermis, but only when combined with mouse or iPSC-derived Schwann cells. This unique model of human innervated TES should be highly useful for the study of cutaneous neuroinflammation. Statement of SignificanceThe purpose of this work was to develop in vitro an innovative fully human tissue-engineered skin enabling the investigation of the influence of cutaneous innervation on skin pathophysiology. To reach that aim, neurons were differentiated from human induced pluripotent stem cells (iPSCs) generated from normal human skin fibroblasts. This innervated tissue-engineered skin model will be the first one to show iPSC-derived neurons can be successfully used to build a 3D nerve network in vitro. Since innervation has been recently recognized to play a central role in many human skin diseases, such as psoriasis and atopic dermatitis, this construct promises to be at the forefront to model these diseases while using patient-derived cells.

Automatic system for optical parameters measurements of biological tissues

In this paper a system allowing execution of automatic measurements of the optical parameters of scattering materials in a efficient and accurate manner is proposed and described. The system is designed especially for measurements of biological tissues including phantoms, which closely imitate optical characteristics of a real tissue. The system has modular construction and is based on ISEL system, luminance and color meter and a computer with worked out dedicated software and user interface. Performed measurements of scattering distribution characteristics for selected materials revealed good accuracy, confirmed by comparative measurements using well-known reference characteristics. Full Text: PDF ReferencesWróbel, M. S., Popov, A. P., Bykov, A. V., Kinnunen, M., Jedrzejewska-Szczerska, M., & Tuchin, V. V. (2015). Measurements of fundamental properties of homogeneous tissue phantoms. Journal of Biomedical Optics CrossRef Wróbel, M. S., Jedrzejewska-Szczerska, M., Galla, S., Piechowski, L., Sawczak, M., Popov, A. P., Cenian, A. (2015). Use of optical skin phantoms for preclinical evaluation of laser efficiency for skin lesion therapy. Journal of Biomedical Optics. CrossRef Jędrzejewska-Szczerska, M., Wróbel, M. S., Galla, S., Popov, A. P., Bykov, A. V., Tuchin, V. V., & Cenian, A. (2015). Investigation of photothermolysis therapy of human skin diseases using optical phantoms. In Proceedings of SPIE - The International Society for Optical Engineering. CrossRef Brown A. M., et al.: Optical material characterization through BSDF measurement and analysis, Proc. of SPIE, Vol. 7792, 2010 CrossRef 4-Axis Controller: iMC-S8. Operating Instruction. ISEL Germany AG, 2012. DirectLink Konica Minolta, Inc. (2005-2013). Chroma meter CS-200. Datasheet. DirectLink Malacara D.: Color Vision and Colorimetry; Theory and Applications, SPIE Press, 2002. DirectLink A. Mazikowski, M. Trojanowski: Measurements of Spectral Spatial Distribution of Scattering Materials for Rear Projection Screens used in Virtual Reality Systems, Metrology and Measurement Systems, 20 (3), pp. 443 - 452, 2013 CrossRef

CARD14/CARMA2 Signaling and its Role in Inflammatory Skin Disorders.

CARMA proteins represent a family of scaffold molecules which play several crucial biological functions, including regulation of immune response and inflammation, tissue homeostasis, and modulation of G-Protein Coupled Receptor (GPCR) signaling. Among the CARMA proteins, CARD14/CARMA2 and its alternatively spliced isoforms are specifically expressed in epithelial cells and keratinocytes. Recent evidences have shown that CARD14/CARMA2 mediates induction of inflammatory response in keratinocytes, and that mutations in CARD14/CARMA2 gene segregate with familial transmission of chronic inflammatory disorders of the human skin. Similarly to CARD11/CARMA1 and CARD10/CARMA3, CARD14/CARMA2 signaling occurs trough formation of a trimeric complex which includes BCL10 and MALT1 proteins. However, it is becoming increasingly evident that in addition to the CBM complex components, a number of accessory molecules are able to finely modulate the signals conveyed on and amplified by CARD14/CARMA2. The study of these molecules is important both to understand the molecular mechanisms that underlie the role of CARMA2 in keratinocytes and because they represent potential therapeutic targets for the development of therapeutic strategies aiming at the treatment of inflammatory diseases of the human skin. In this review, we provide an overview on the molecular mechanisms mediating CARD14/CARMA2 signaling and its implication in our understanding of the pathogenesis of human inflammatory skin disorders.

Occurrence of Demodex species in patients with blepharitis and in healthy individuals: a 10-year observational study.

Two Demodex species (eyelash mites)-D. folliculorum and D brevis-are believed to be associated with human skin and eye diseases. However, the clinical significance of infection with Demodex species remains controversial. The aim of this study was to estimate the prevalence of ocular demodicosis in patients with blepharitis as compared with the prevalence in the healthy population in Poland. This case-control prospective study was carried out from 2007 to 2016. The enrolled patients (668) were divided into 2 groups: the study group, comprising 553 patients with blepharitis (349 women and 204 men, aged 17-88 years), and the control group, comprising 115 healthy volunteers without a history of ocular pathologies (78 women and 37 men, aged 17-88 years). A sample of 10 eyelashes was taken aseptically from each eye of the examined person and later studied under a light microscope. Demodex species were found in 62.4% (345/544) of the patients in the study group and in 24.3% (28/100) of the controls (P = .001, OR = 0.006). The overall prevalence was 55.8% (373/668) in all the examined participants. The presence of Demodex infection increased with age in both groups. No association of Demodex infection with gender was found (119/204 vs 226/349; P > .05, OR 1.086). A high mean number of mites was present more frequently in patients aged older than 50 years and in those who complained especially about itching (P < .05). The prevalence of ocular demodicosis is significantly correlated with blepharitis and increases with age.

International Investigative Dermatology 2018 Meeting: Promoting Global Skin Biology and Skin Disease Research

International Investigative Dermatology 2018 Meeting: Promoting Global Skin Biology and Skin Disease Research

Yeast-Based Screen to Identify Natural Compounds with a Potential Therapeutic Effect in Hailey-Hailey Disease.

The term orthodisease defines human disorders in which the pathogenic gene has orthologs in model organism genomes. Yeasts have been instrumental for gaining insights into the molecular basis of many human disorders, particularly those resulting from impaired cellular metabolism. We and others have used yeasts as a model system to study the molecular basis of Hailey-Hailey disease (HHD), a human blistering skin disorder caused by haploinsufficiency of the gene ATP2C1 the orthologous of the yeast gene PMR1. We observed that K. lactis cells defective for PMR1 gene share several biological similarities with HHD derived keratinocytes. Based on the conservation of ATP2C1/PMR1 function from yeast to human, here we used a yeast-based assay to screen for molecules able to influence the pleiotropy associated with PMR1 deletion. We identified six compounds, Kaempferol, Indirubin, Lappaconite, Cyclocytidine, Azomycin and Nalidixic Acid that induced different major shape phenotypes in K. lactis. These include mitochondrial and the cell-wall morphology-related phenotypes. Interestingly, a secondary assay in mammalian cells confirmed activity for Kaempferol. Indeed, this compound was also active on human keratinocytes depleted of ATP2C1 function by siRNA-treatment used as an in-vitro model of HHD. We found that Kaempferol was a potent NRF2 regulator, strongly inducing its expression and its downstream target NQO1. In addition, Kaempferol could decrease oxidative stress of ATP2C1 defective keratinocytes, characterized by reduced NRF2-expression. Our results indicated that the activation of these pathways might provide protection to the HHD-skin cells. As oxidative stress plays pivotal roles in promoting the skin lesions of Hailey-Hailey, the NRF2 pathway could be a viable therapeutic target for HHD.

Development of Dermatological Skin Disease Detection and Classification based on Wavelet and ANN

One of the most common and augmenting health problems in the world are related to skin. The most unpredictable and one of the most difficult entities to automatically detect and evaluate is the human skin disease because of complexities of texture, tone, presence of hair and other distinctive features. Many cases of skin diseases in the world have triggered a need to develop an effective automated screening method for detection and diagnosis of the area of disease. Therefore the objective of this work is to develop a new technique for automated detection and analysis of the skin disease images based on color and texture information for skin disease screening. In this paper, system is proposed which detects the skin diseases using Wavelet Techniques and Artificial Neural Network. This paper presents a wavelet-based texture analysis method for classification of five types of skin diseases. The method applies tree-structured wavelet transform on different color channels of red, green and blue dermoscopy images, and employs various statistical measures and ratios on wavelet coefficients. In all 99 unique features are extracted from the image. By using Artificial Neural Network, the system successfully detects different types of dermatological skin diseases. It consists of mainly three phases image processing, training phase, detection and classification phase.

Review: Dermatological Skin Disease Detection and Classification Based on Wavelet Transform and Artificial Neural Network

One of the most common and augmenting health problems in the world are related to skin. The most unpredictable and one of the most difficult entities to automatically detect and evaluate is the human skin disease because of complexities of texture, tone, presence of hair and other distinctive features. Many cases of skin diseases in the world have triggered a need to develop an effective automated screening method for detection and diagnosis of the area of disease. Therefore the objective of this work is to develop a new technique for automated detection and analysis of the skin disease images based on color and texture information for skin disease screening. In this paper, system is proposed which detects the skin diseases using Wavelet Techniques and Artificial Neural Network. This paper presents a wavelet-based texture analysis method for classification of five types of skin diseases. The method applies tree-structured wavelet transform on different color channels of red, green and blue dermoscopy images, and employs various statistical measures and ratios on wavelet coefficients. In all 99 unique features are extracted from the image. By using Artificial Neural Network, the system successfully detects different types of dermatological skin diseases. It consists of mainly three phases image processing, training phase, detection and classification phase.

Diagnostics of Malassezia Species: A Review

Abstract Yeasts from the genus Malassezia belongs to normal commensal skin flora of warm-blooded vertebrates. These yeasts may act as opportunistic pathogens and cause skin diseases in humans and animals under certain conditions. The identification of Malassezia species is based on the phenotypic or genotypic diagnostics. The methods used for the phenotypic identification is determined by: the growth on Sabouraud agar, growth on selective media (Leeming-Notman agar, Dixon agar, Chrom Malassezia agar), the ability to utilise different concentrations of Tween, monitoring of the growth on CEL agar (soil enriched with castor oil) and TE agar (Tween-esculine agar), and the catalase test. The genotypic identification uses molecular methods like: the pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), amplified fragment lenght polymorphism (AFLP), denaturing gradient gel electrophoresis (DGGE), and the DNA sequence analysis.

Protease-mediated Inflammation: An In Vitro Human Keratinocyte-based Screening Tool for Anti-inflammatory Drug Nanocarrier Systems

Abstract Background: Refined encapsulation approaches in dermatotherapy gain increased interest. There is need of reproducible in vitro systems representing disease features to screen drug delivery systems for preclinical assessment. Inflammatory human skin diseases are commonly accompanied by abnormal epidermal differentiation and barrier impairment. Serine proteases (SPs) and their inhibitors play a critical role in such dysfunctional differentiation. SPs also initiate cellular pathways via activation of protease-activated receptors, which contribute to inflammation. Thus, function and activity of SPs should be considered for the design of new therapies of such disorders. Objectives: Herein, we established a novel simplified cell culture model, based on SP-mediated inflammation suitable to assess nanocarriers loaded with anti-inflammatory drugs. Methods: SP-mediated inflammation and the regulatory effect of free or encapsulated dexamethasone were determined by measuring interleukin-6 and interleukin-8 in culture medium of HaCaT (human adult low calcium temperature)-keratinocytes. Additionally, radical formation was analyzed by electron paramagnetic resonance spectroscopy. Cellular uptake of core-multishell nanocarriers was investigated by fluorescence microscopy. Cytotoxicity of all additives was determined by a viability assay. Results: SP-Stimulation of keratinocytes resulted in increased radical production and release of inflammatory cytokines without affecting cell viability. Induced inflammation was successfully downregulated by addition of free or encapsulated dexamethasone. Conclusion: SP-addition can be used as inflammatory stimulus in cell culture to mimic effects of aberrant enzymatic activities found in skin of atopic dermatitis patients. The set-up is appropriate as a preliminary test to examine the effectiveness of new molecules or delivery-systems to counteract serine protease-mediated inflammatory processes prior to skin studies.

Assessment of Traditional Medicinal Plants Used for Treatment of Human Diseases in Oromia Region, West Shewa Zone: Jeldu Woreda, Ethiopia

Most of the information regarding traditional medicinal plants are still in the hands of traditional vendors, and knowledge of vendors is either lost or passed orally from generation to next generation. This study aimed to survey and document the currently used plants by herbalists in Jeldu Woreda and record their medicinal usage and mode of preparation. Due to most of the vendors of traditional medicinal plants in Jeldu Woreda are alliterated, the data was gathered by supported questionnaire from both vendors and the users of this traditional medicinal plants. The study was limited to traditional medicinal plants which used to treat diseases related to skin, digestive system and circulatory system. The technique used to select the sample from the traditional medicinal plant venders was available sampling since the number of venders in the selected site is not large in number. Thus all the traditional medicinal plant venders in Jeldu Woreda were the respondents of the study. From selected research site about 21 medicinal plants vendorsand 47 users were participated in the study. The finding of the study concluded that there were some plants used to treat some human disease in Jeldu Woreda. Therefore, this research tried to document some medicinal plants used to treat human gastrointestinal, skin and other diseases by including the mode of preparation and how to apply. In this research about 68 respondents have participated. Out of those respondents, 21 were vendors of medicinal plants while 47 were users of medicinal plants. According to data from the medicinal plant vendors and users total of 26 plant species were identified with an identification of the plants’ part with medicinal value. Also, the modes of preparation and mode of application were described in this research. Among this plants species, more than half of them used to treat digestive system disease. From the 26 plant species about half of those plants were recorded for their ability to treat skin disease. The application of the prepared medicine on the skin is mostly by painting the liquidified medicine from plant on infected skin.

Skin Stem Cells in Silence, Action, and Cancer.

In studying how stem cells make and maintain tissues, nearly every chapter of a cell biology textbook takes on special interest. The field even allows us to venture where no chapters have yet been written. In studying this basic problem, we are continually bombarded by nature's surprises and challenges. Stem cell biology has captured my interest for nearly my entire scientific career. Below, I focus on my laboratory's contributions to this fascinating field, to which so many friends and colleagues have made seminal discoveries equally deserving of this award.

Transcriptomic profiling of human skin biopsies in the clinical trial setting: A protocol for high quality RNA extraction from skin tumours.

Transcriptomic profiling of skin disease using next generation sequencing allows for detailed information on aspects of RNA biology including gene expression, non-coding regulatory elements and gene splicing. The application of RNA sequencing to human skin disease and cancer is often hampered by degraded RNA. Here we describe a protocol that allows for consistently intact RNA to be extracted from snap frozen skin biopsy samples, which has been validated in a clinical trial setting. Human skin tumour punch biopsies (n=28) ranging from 4-6mm in diameter were obtained from 14 patients with an inherited skin tumour syndrome (CYLD cutaneous syndrome) and frozen in liquid nitrogen prior to being stored at -80°C. These samples were then subject to cyrostat sectioning, allowing for histological assessment, and were homogenised using a bead-based lysis platform. RNA extraction was performed using a silica column-based system. RNA concentration was measured using fluorescent quantitation and RNA integrity assessed using microfluidic gel electrophoresis. We also processed normal skin biopsies using the same protocol (n=10). The mean RNA integrity score of the tumour and normal samples was 9.5, and the quantity of RNA obtained from the small amounts of tissue used exceeded requirements for RNA-seq library generation. We propose that the method of RNA extraction suggested here allows for transcriptomic profiling from small pieces of human tissue without the need for PCR amplification during library preparation. This protocol could be utilised in healthy and diseased skin to improve mechanistic understanding in a range of human skin diseases.

826 Genetic deletion of amphiregulin restores the normal skin phenotype in a mouse model of the human skin disease tylosis

In humans, gain-of-function (GOF) mutations in RHBDF2 cause the skin disease tylosis. We generated a mouse model of human tylosis and show that GOF mutations in RHBDF2 cause tylosis by enhancing the amount of AREG secretion. Additionally, we demonstrate that ADAM17 is an essential sheddase of AREG , and mouse models of tylosis lacking ADAM17 specifically in the skin exhibit a full hair coat with no signs of hyperplasia or hyperkeratosis. Furthermore, we show that genetic disruption of AREG ameliorates skin pathology in mice carrying the human tylosis disease mutation. Collectively, our data suggest that RHBDF2 plays a critical role in regulating EGFR signaling and its downstream events, including development of tylosis, by facilitating enhanced secretion of AREG via ADAM17. Thus, targeting AREG could have therapeutic benefit in the treatment of tylosis.