Transcriptomic profiling of recessive dystrophic epidermolysis bullosa wounded skin highlights drug repurposing opportunities to improve wound healing.

Chronic wounds present a major disease burden in people with recessive dystrophic epidermolysis bullosa (RDEB), an inherited blistering skin disorder caused by mutations in COL7A1 encoding type VII collagen, the major component of anchoring fibrils at the dermal-epidermal junction. Treatment of RDEB wounds is mostly symptomatic, and there is considerable unmet need in trying to improve and accelerate wound healing. In this study, we defined transcriptomic profiles and gene pathways in RDEB wounds and compared these to intact skin in RDEB and healthy control subjects. We then used a reverse transcriptomics approach to discover drugs or compounds, which might restore RDEB wound profiles towards intact skin. Differential expression analysis identified >2000 differences between RDEB wounds and intact skin, with RDEB wounds displaying aberrant cytokine-cytokine interactions, Toll-like receptor signalling, and JAK-STAT signalling pathways. In-silico prediction for compounds that reverse gene expression signatures highlighted methotrexate as a leading candidate. Overall, this study provides insight into the molecular profiles of RDEB wounds and underscores the possible clinical value of reverse transcriptomics data analysis in RDEB, and the potential of this approach in discovering or repurposing drugs for other diseases.

Prescribing practices for systemic agents in the treatment of severe pediatric atopic dermatitis in the US and Canada: The PeDRA TREAT survey.

BACKGROUND: There is a paucity of literature to direct physicians in the prescribing of immunomodulators for patients with severe atopic dermatitis (AD). OBJECTIVE: To survey systemic agent prescribing practices for severe childhood AD among clinicians in the United States and Canada. METHODS: The TREatment of severe Atopic dermatitis in children Taskforce (TREAT), US&CANADA, a project of the Pediatric Dermatology Research Alliance (PeDRA), developed an online multiple-response survey to assess clinical practice, gather demographic information and details of systemic agent selection, and identify barriers to their use in patients with recalcitrant pediatric AD. RESULTS: In total, 133 of 290 members (45.9%) of the Society for Pediatric Dermatology completed the survey, and 115 of 133 (86.5%) used systemic treatment for severe pediatric AD. First-line drugs of choice were cyclosporine (45.2%), methotrexate (29.6%), and mycophenolate mofetil (13.0%). The most commonly used second-line agents were methotrexate (31.3%) and mycophenolate mofetil (30.4%); azathioprine was the most commonly cited third-line agent. The main factors that discouraged use of systemic agents were side-effect profiles (82.6%) and perceived risks of long-term toxicity (81.7%). LIMITATIONS: Investigation of the sequence of systemic medications or combination systemic therapy was limited. Recall bias may have affected the results. CONCLUSION: Great variation exists in prescribing practices among American and Canadian physicians using systemic agents for treatment of pediatric AD.

Mutations in GRHL2 result in an autosomal-recessive ectodermal Dysplasia syndrome.

Grainyhead-like 2, encoded by GRHL2, is a member of a highly conserved family of transcription factors that play essential roles during epithelial development. Haploinsufficiency for GRHL2 has been implicated in autosomal-dominant deafness, but mutations have not yet been associated with any skin pathology. We investigated two unrelated Kuwaiti families in which a total of six individuals have had lifelong ectodermal defects. The clinical features comprised nail dystrophy or nail loss, marginal palmoplantar keratoderma, hypodontia, enamel hypoplasia, oral hyperpigmentation, and dysphagia. In addition, three individuals had sensorineural deafness, and three had bronchial asthma. Taken together, the features were consistent with an unusual autosomal-recessive ectodermal dysplasia syndrome. Because of consanguinity in both families, we used whole-exome sequencing to search for novel homozygous DNA variants and found GRHL2 mutations common to both families: affected subjects in one family were homozygous for c.1192T>C (p.Tyr398His) in exon 9, and subjects in the other family were homozygous for c.1445T>A (p.Ile482Lys) in exon 11. Immortalized keratinocytes (p.Ile482Lys) showed altered cell morphology, impaired tight junctions, adhesion defects, and cytoplasmic translocation of GRHL2. Whole-skin transcriptomic analysis (p.Ile482Lys) disclosed changes in genes implicated in networks of cell-cell and cell-matrix adhesion. Our clinical findings of an autosomal-recessive ectodermal dysplasia syndrome provide insight into the role of GRHL2 in skin development, homeostasis, and human disease.

Epithelial inflammation resulting from an inherited loss-of-function mutation in EGFR.

Epidermal growth factor receptor (EGFR) signaling is fundamentally important for tissue homeostasis through EGFR/ligand interactions that stimulate numerous signal transduction pathways. Aberrant EGFR signaling has been reported in inflammatory and malignant diseases, but thus far no primary inherited defects in EGFR have been recorded. Using whole-exome sequencing, we identified a homozygous loss-of-function missense mutation in EGFR (c.1283 G>A; p.Gly428Asp) in a male infant with lifelong inflammation affecting the skin, bowel, and lungs. During the first year of life, his skin showed erosions, dry scale, and alopecia. Subsequently, there were numerous papules and pustules--similar to the rash seen in patients receiving EGFR inhibitor drugs. Skin biopsy demonstrated an altered cellular distribution of EGFR in the epidermis with reduced cell membrane labeling, and in vitro analysis of the mutant receptor revealed abrogated EGFR phosphorylation and EGF-stimulated downstream signaling. Microarray analysis on the patient's skin highlighted disturbed differentiation/premature terminal differentiation of keratinocytes and upregulation of several inflammatory/innate immune response networks. The boy died at the age of 2.5 years from extensive skin and chest infections as well as electrolyte imbalance. This case highlights the major mechanism of epithelial dysfunction following EGFR signaling ablation and illustrates the broader impact of EGFR inhibition on other tissues.

Inherited blistering skin diseases: underlying molecular mechanisms and emerging therapies.

A key function of human skin is the formation of a structural barrier against the external environment. In part, this is achieved through the formation of a cornified cell envelope derived from a stratified squamous epithelium attached to an epithelial basement membrane. Resilient in health, the structural integrity of skin can become impaired or break down in a collection of inherited skin diseases, referred to as the blistering genodermatoses. These disorders arise from inherited gene mutations in a variety of structural and signalling proteins and manifest clinically as blisters or erosions following minor skin trauma. In some patients, blistering can be severe resulting in significant morbidity. Furthermore, a number of these conditions are associated with debilitating extra-cutaneous manifestations including gastro-intestinal, cardiac, and ocular complications. In recent years, an improved understanding of the molecular basis of the blistering genodermatoses has led to better disease classification and genetic counselling. For patients, this has also advanced translational research with the advent of new clinical trials of gene, protein, cell, drug, and small molecule therapies. Although curing inherited blistering skin diseases still remains elusive, significant improvements in patients' quality of life are already being achieved.

Serum levels of high mobility group box 1 correlate with disease severity in recessive dystrophic epidermolysis bullosa.

In the inherited blistering skin disease, recessive dystrophic epidermolysis bullosa (RDEB), there is clinical heterogeneity with variable scarring and susceptibility to malignancy. Currently, however, there are few biochemical markers of tissue inflammation or disease progression. We assessed whether the non-histone nuclear protein, high mobility group box 1 (HMGB1), which is released from necrotic cells (including keratinocytes in blister roofs), might be elevated in RDEB and whether this correlates with disease severity. We measured serum HMGB1 by ELISA in 26 RDEB individuals (median 21.0 ng/ml, range 3.6-54.9 ng/ml) and 23 healthy controls (median 3.6, range 3.4-5.9 ng/ml) and scored RDEB severity using the Birmingham Epidermolysis Bullosa Severity Score (BEBSS; mean 34/100, range 8-82). There was a positive relationship between the BEBSS and HMGB1 levels (r = 0.54, P = 0.004). This study indicates that serum HMGB1 levels may represent a new biomarker reflecting disease severity in RDEB.

A retrospective study of the management of pediatric kerion in Trichophyton tonsurans infection.

Kerion celsi is the inflammatory extreme of tinea capitis, representing a delayed hypersensitivity reaction to the causative dermatophyte. Some authors have advocated the use of oral corticosteroids in patients with kerion formation to inhibit the host inflammatory response and minimize the risk of scarring. This retrospective study analyzed the management and outcome of all children younger than 10 years old presenting to our pediatric dermatology service with tinea capitis resulting in kerion formation between 2003 and 2009. We propose that kerion treatment be directed toward the underlying dermatophyte. Oral and intralesional corticosteroids are an unnecessary adjunct to oral antifungal therapy for children with tinea capitis presenting with kerion in urban areas.