HaCaT cells as a model system to study primary cilia in keratinocytes.

Primary cilium (PC) is a microtubule-based organelle found on the apical surface of most mammalian cell types, playing a role in development and tissue homeostasis. Ciliopathies are a rapidly growing group of human diseases characterized by disordered cilium. PC plays an important role in pathogenesis of basal cell cancer, the most common human malignancy. A significant increase in ciliation has been observed in the epidermis of atopic dermatitis and psoriasis patients. Spontaneously immortalized human keratinocytes, HaCaT are a model to study the epidermal homeostasis and pathophysiology. In contrast to what has been previously described, here, we show that HaCaT can be efficiently ciliated. In HaCaT cells, differentiation significantly increased the number of ciliated cells and we were able to analyse in detail the ciliary length progression with duration of differentiation. As the number of recognized ciliopathies continues to increase, the importance of ciliary models also rises. Even though keratinocytes do not become as highly and rapidly ciliated as cell lines frequently used in ciliary studies, they are a better model for the study of skin ciliopathies. Detailed progression of ciliation in HaCaT could serve as the basis for ciliary studies in this cell line.

Evaluation of neurodevelopmental symptoms in 10 cases of neonatal ichthyosis and sclerosing cholangitis syndrome.

Neonatal ichthyosis and sclerosing cholangitis (NISCH) syndrome is an extremely rare entity with only 19 patients described in the literature. We report an extended family with the disorder and investigate the association of neurodevelopmental symptoms. Patients with CLDN1 mutations, and specifically « the Moroccan¼ c.200_201delTT deletion, may be an increased risk for neurodevelopmental symptoms such as learning disabilities, mental retardation, and language delay.

The Fate of Epidermal Tight Junctions in the stratum corneum: Their Involvement in the Regulation of Desquamation and Phenotypic Expression of Certain Skin Conditions.

We evaluated the presence of tight junction (TJ) remnants in the stratum corneum (SC) of in vitro reconstructed human epidermis and human skin explants subjected or not to an aggressive topical treatment with beta-lipohydroxy salicylic acid (LSA) for 24 h. LSA-treated samples showed an increased presence of TJ remnants in the two lowermost layers of the SC, as quantified with standard electron microscopy. The topical aggression-induced overexpression of TJ-like cell-cell envelope fusions may influence SC functions: (1) directly, through an enhanced cohesion, and (2) indirectly, by impeding accessibility of peripheral corneodesmosomes to extracellular hydrolytic enzymes and, thus, slowing down desquamation. Observations of ichthyotic epidermis in peeling skin disease (PSD; corneodesmosin deficiency; two cases) and ichthyosis hypotrichosis sclerosing cholangitis syndrome (IHSC/NISCH; absence of claudin-1; two cases) also demonstrated increased persistence of TJ-like intercellular fusions in pathological SC and contributed to the interpretation of the diseases' pathological mechanisms.

Treatment of Impetigo and Antimicrobial Resistance.

BACKGROUND: Impetigo is a contagious bacterial infection that affects the superficial skin layers. Increasing worldwide antimicrobial resistance (AMR) to existing topical agents commonly prescribed to treat impetigo is central to treatment failure. The Worldwide Health Organization developed a global action plan on AMR, but omitted information about AMR stewardship programs for topical antibiotics. OBJECTIVES: The review aims to provide information to clinicians and stakeholders regarding AMR and antimicrobial stewardship on topical antimicrobial drugs for impetigo treatment. METHODS: The literature searches reviewed the status of AMR to current topical antibiotics in impetigo, current therapeutic behavior, and concordance with antimicrobial stewardship principles. Two international panels convened to discuss the output of the searches, and the results of the panel discussions were used in the development of the manuscript. RESULTS: The literature search included clinical trials, research studies, clinical guidelines, consensus papers, and reviews (if they provided original data), published between January 2008 and May 2019. The articles were selected based on clinical relevancy of impetigo management, clinical efficacy, and safety of the treatment and antimicrobial resistance. The searches resulted in one-hundred and ninety-eight articles. After applying the eligibility criteria, nineteen articles met inclusion criteria and were considered in the present review. CONCLUSIONS: While published antimicrobial stewardship guidelines have focused on systemic antibiotics, few studies have attempted to evaluate topical antibiotic prescribing practices for impetigo treatment. Many of the topical impetigo treatments currently in use have developed resistance. The appropriate use of topical ozenoxacin can help eradicate impetigo while minimizing AMR.J Drugs Dermatol. 20(4):366-372. doi:10.36849/JDD.5795.

Diaper dermatitis prevalence and severity: Global perspective on the impact of caregiver behavior.

OBJECTIVES: To compare prevalence and severity of diaper dermatitis (DD) in infants and toddlers (babies) across three countries (China, USA, and Germany), including diapered skin measures and caregiver practices. METHODS: A cross-sectional study of 1791 babies (~600 from each country) was recruited at each clinical site. Based on regional toilet-training habits, exclusively diaper-wearing infants were recruited between ages 2-8 months in China and 2-18 months in the USA and Germany. DD was measured, as well as skin pH, transepidermal water loss (TEWL), and relative humidity (RH) in the diapered region. Caregiver habits were collected via a questionnaire and included information on hygienic practices. RESULTS: Diaper dermatitis was highest in the perianal area, followed by the intertriginous, genital, and buttock regions. In general, DD was significantly lower in babies in China, highest in Germany, and intermediate in the USA. This rank ordering of DD by geography was also observed in baby age 2-8 months. The lower DD observed in China was associated with lower skin pH and TEWL on diapered skin and decreased RH in the diaper. Chinese caregivers had the highest rate of prophylactic topical product usage, the most robust cleaning of the diapered area, lack of cleansing after urine-only diaper changes, and Chinese infants spent the least time in an overnight diaper. CONCLUSIONS: These data suggest caregiver behaviors including prophylactic use of topical products, thorough cleaning after stooling and reduced time in an overnight diaper are associated with less DD, lower superficial skin pH, and enhanced skin barrier.

[Digital pathology for the dermatologist]. / Pathologie digitale pour le dermato.

Recent progress in molecular engineering, digital imaging and artificial intelligence improve human modern medicine to levels never seen before. Digital pathology becomes the new standard of patient care in dermatology and personalized medicine. It is increasingly used for digital exchange of histological slides, personalized consultations, tumor boards, quantitative image analysis for research purposes and in education. Digital pathology allows automatization and quantification with greater consistency and accuracy than light microscopy. Personalized dermatology is focusing on tailoring therapy to the individual characteristics of each patient and allow to use genetic information in order to develop a treatment plan, uniquely suited to each patient, which in turn leads to improved quality of care and management of each individual.

L'ingénierie moléculaire, l'imagerie digitale et l'intelligence artificielle (IA) améliorent la médecine moderne à des niveaux jamais vus auparavant. La pathologie digitale (PD) est progressivement utilisée pour l'échange digital de lames histologiques produites en routine, les consultations personnalisées, les tumor boards, l'analyse quantitative d'images à des buts de recherche et dans l'éducation, et enfin l'archivage. La PD permet l'automatisation et la quantification avec plus de cohérence et de précision que la microscopie optique. La dermatologie personnalisée se concentre sur l'adaptation de la thérapie aux caractéristiques individuelles de chaque patient et permet d'utiliser les données génétiques afin de développer un plan de traitement individuellement adapté, en améliorant la qualité des soins et la prise en charge.

IL-17 receptor A and adenosine deaminase 2 deficiency in siblings with recurrent infections and chronic inflammation.

BACKGROUND: Data on patients affected by chronic mucocutaneous candidiasis underscore the preponderant role of IL-17 receptor A (IL-17RA) in preserving mucocutaneous immunity. Little is known about the role of adenosine deaminase (ADA) 2 in regulation of immune responses, although recent reports linked ADA2 deficiency with inflammation and vasculitis. OBJECTIVE: We sought to investigate the mechanisms of chronic inflammation and vasculitis in a child lacking IL-17RA and ADA2 to identify therapeutic targets. METHODS: We report a family with 2 siblings who have had recurrent mucocutaneous infections with Candida albicans and Staphylococcus aureus and chronic inflammatory disease and vasculitis since early childhood, which were refractory to classical treatments. Array-based comparative genomic hybridization analysis showed that both siblings are homozygous for a 770-kb deletion on chr22q11.1 encompassing both IL17RA and cat eye critical region 1 (CECR1). Immunologic studies were carried out by means of flow cytometry, ELISA, and RIA. RESULTS: As expected, in the affected child we found a lack of IL-17RA expression, which implies a severe malfunction in the IL-17 signaling pathway, conferring susceptibility to recurrent mucocutaneous infections. Surprisingly, we detected an in vitro and in vivo upregulation of proinflammatory cytokines, notably IL-1ß and TNF-α, which is consistent with the persistent systemic inflammation. CONCLUSIONS: This work emphasizes the utility of whole-genome analyses combined with immunologic investigation in patients with unresolved immunodeficiency. This approach is likely to provide an insight into immunologic pathways and mechanisms of disease. It also provides molecular evidence for more targeted therapies. In addition, our report further corroborates a potential role of ADA2 in modulating immunity and inflammation.

[Rare vascular diseases, building dedicated multidisciplinary specialized center]. / Maladies vasculaires rares, mise en place d'un centre multidisciplinaire spécialisé au CHUV.

Rare Vascular Diseases (RVD) encompass different types of vessel involvement. Some cause a dilation, others a weakening or tortuosity of the arterial wall, others an obstruction or excessive calcification of arterial walls. Clinical pathway of patients with RVD to diagnosis is often long and complex. Thus, in order to allow early diagnosis and coordinated multidisciplinary management and follow-up, a specialized RVD centre has been set-up at the CHUV, following the framework of the national concept of rare diseases.

Les maladies vasculaires rares (MVR) englobent différents types d'atteintes des vaisseaux. Certaines engendrent une dilatation ou une tortuosité de la paroi artérielle, d'autres une fragilisation de la paroi, d'autres encore entraînent une obstruction du vaisseau, une calcification excessive des parois, ou des malformations vasculaires. Comme pour toutes les maladies rares, le parcours des patients vers un diagnostic est souvent long et complexe. Afin de permettre un diagnostic le plus précoce possible, ainsi qu'un suivi coordonné et une prise en charge multidisciplinaire médicale et sociale, un centre des MVR a été mis en place au CHUV, dans le cadre du concept national des maladies rares.

TRAIP is a regulator of the spindle assembly checkpoint.

Accurate chromosome segregation during mitosis is temporally and spatially coordinated by fidelity-monitoring checkpoint systems. Deficiencies in these checkpoint systems can lead to chromosome segregation errors and aneuploidy, and promote tumorigenesis. Here, we report that the TRAF-interacting protein (TRAIP), a ubiquitously expressed nucleolar E3 ubiquitin ligase important for cellular proliferation, is localized close to mitotic chromosomes. Its knockdown in HeLa cells by RNA interference (RNAi) decreased the time of early mitosis progression from nuclear envelope breakdown (NEB) to anaphase onset and increased the percentages of chromosome alignment defects in metaphase and lagging chromosomes in anaphase compared with those of control cells. The decrease in progression time was corrected by the expression of wild-type but not a ubiquitin-ligase-deficient form of TRAIP. TRAIP-depleted cells bypassed taxol-induced mitotic arrest and displayed significantly reduced kinetochore levels of MAD2 (also known as MAD2L1) but not of other spindle checkpoint proteins in the presence of nocodazole. These results imply that TRAIP regulates the spindle assembly checkpoint, MAD2 abundance at kinetochores and the accurate cellular distribution of chromosomes. The TRAIP ubiquitin ligase activity is functionally required for the spindle assembly checkpoint control.

Keratoacanthoma: a distinct entity?

Keratoacanthoma (KA) are common but exceptional benign tumors, often appearing on sun-exposed areas of light skinned people and showing spontaneous resolution. The goal of this study was to review existing literature, to point out the etiological complexity of KA biology and to answer the controversial debate if or not KA is a distinct entity or a variant of squamous cell carcinoma (SCC). Relying on recent results, we highlight that KA is an individual lesion with a unique molecular signature caused by alterations in the TGFß signalling pathway. These recent findings will help to understand the nature of KA and to develop new reliable diagnostic tools, simplifying the discrimination of the histologically similar KA and SCC.

PASS Syndrome: An IL-1-Driven Autoinflammatory Disease.

PASS syndrome is a rare inflammatory disease characterized by a chronic-relapsing course of pyoderma gangrenosum, acne vulgaris, hidradenitis suppurativa and ankylosing spondylitis. Here, we describe a case of a patient with spontaneously recurrent purulent skin lesions along with seronegative spondylarthritis consistent with the PASS syndrome. During his disease exacerbation, the patient displayed episodes of fever along with elevated serum levels of interleukin (IL)-1ß. Skin lesions were characterized by sterile neutrophilic infiltrates and showed a rapid response to the IL-1 receptor antagonist anakinra (Kineret®) consistent with the autoinflammatory nature of this disease. However, unlike other autoinflammatory diseases such as PAPA and PAPASH, we did not find mutations in the gene PSTPIP1, raising the possibility that other specific mutations in the IL-1 pathway may be involved.

[The skin microbiota: a colossus steps into the spotlight]. / Le microbiote cutané: le poids lourd sort de l'ombre.

The skin contains many commensal bacteria. For years, these microbes have been considered to be exploiters of the human host for nutrients. However, recent findings indicates that the skin microbiota is also used by the human host to protect himself against invading pathogens as the commensal bacteria have direct antimicrobial capacity and provide factors required to mount a protective immune responses in the skin. While the healthy skin microbiome functions as guardians of host defense, increased or decreased bacterial composition of the skin microbiome (called dysbiosis) leads to skin inflammation and disease. Here we will review the emerging data on the role of distinct types of dysbiosis in the pathogenesis skin diseases and illustrate how the new understanding of the role of the skin microbiome has implications in the clinical management of skin diseases.

Mast cells are dispensable for normal and activin-promoted wound healing and skin carcinogenesis.

The growth and differentiation factor activin A is a key regulator of tissue repair, inflammation, fibrosis, and tumorigenesis. However, the cellular targets, which mediate the different activin functions, are still largely unknown. In this study, we show that activin increases the number of mature mast cells in mouse skin in vivo. To determine the relevance of this finding for wound healing and skin carcinogenesis, we mated activin transgenic mice with CreMaster mice, which are characterized by Cre recombinase-mediated mast cell eradication. Using single- and double-mutant mice, we show that loss of mast cells neither affected the stimulatory effect of overexpressed activin on granulation tissue formation and reepithelialization of skin wounds nor its protumorigenic activity in a model of chemically induced skin carcinogenesis. Furthermore, mast cell deficiency did not alter wounding-induced inflammation and new tissue formation or chemically induced angiogenesis and tumorigenesis in mice with normal activin levels. These findings reveal that mast cells are not major targets of activin during wound healing and skin cancer development and also argue against nonredundant functions of mast cells in wound healing and skin carcinogenesis in general.

[What's new in pediatric dermatology]. / Quoi de neuf en dermatologie pédiatrique?

Progress in paediatric dermatology is achieved in both research and therapeutic fields. In infectiology, scabies and bed bugs are a scourge for dermatologists, with an important recent outbreak. This article describes the fundamental clinical signs to look for, when suspecting such diagnosis. Hair dermatoscopy seems to be also very precious as a new tool for the diagnosis of ringworm. Regarding eczemas, atopic dermatitis is supported by S. Aureus's skin colonization, the target of eradication of new products in ongoing studies. We will also explain the role of Hemangiol, recently marketed in Switzerland for the treatment of haemangiomas. Alternative beta blockers have also a large number of ongoing projects in the dermatological vascular diseases field. Other various news is to be discovered....

Cutaneous cancer stem cell maintenance is dependent on beta-catenin signalling.

Continuous turnover of epithelia is ensured by the extensive self-renewal capacity of tissue-specific stem cells. Similarly, epithelial tumour maintenance relies on cancer stem cells (CSCs), which co-opt stem cell properties. For most tumours, the cellular origin of these CSCs and regulatory pathways essential for sustaining stemness have not been identified. In murine skin, follicular morphogenesis is driven by bulge stem cells that specifically express CD34. Here we identify a population of cells in early epidermal tumours characterized by phenotypic and functional similarities to normal bulge skin stem cells. This population contains CSCs, which are the only cells with tumour initiation properties. Transplants derived from these CSCs preserve the hierarchical organization of the primary tumour. We describe beta-catenin signalling as being essential in sustaining the CSC phenotype. Ablation of the beta-catenin gene results in the loss of CSCs and complete tumour regression. In addition, we provide evidence for the involvement of increased beta-catenin signalling in malignant human squamous cell carcinomas. Because Wnt/beta-catenin signalling is not essential for normal epidermal homeostasis, such a mechanistic difference may thus be targeted to eliminate CSCs and consequently eradicate squamous cell carcinomas.

Syndrome of Birt-Hogg-Dubé, a histopathological pitfall with similarities to tuberous sclerosis: a report of three cases.

Birt-Hogg-Dubé Syndrome (BHD) is a rare condition, transmitted as an autosomal-dominant trait. The etiology is due to a mutation in the BHD gene, which encodes folliculin (FLCN), located on chromosome 17p. The skin changes observed are benign skin tumors consisting of hamartomas of the hair follicle with dermal changes. Patients with BHD have an increased risk of spontaneous pneumothorax due to rupture of lung cysts and an increased risk of kidney tumors. We report 3 new cases of BHD and discuss their clinical features, histopathological findings, and molecular diagnostics. We highlight the importance of genetic analysis to confirm the diagnosis because of the clinical pitfalls involved in establishing a diagnosis. Finally, we discuss the histopathological features in BHD and tuberous sclerosis complex and focus on their overlapping criterias. A correct diagnosis is essential as it can be life saving for patients.

Localized interstitial granuloma annulare induced by subcutaneous injections for desensitization.

We describe a patient with interstitial granuloma annulare associated with subcutaneous injection therapy (SIT) for desensitization to a type I allergy. Asymptomatic, erythematous, violaceous annular patches were located at the injection sites on both her arms. Medical history revealed perennial rhinoconjonctivitis treated with SIT (Phostal Stallergen® cat 100% and D. pteronyssinus/D.farinae 50%:50%).