May El Hachem

Proteolytic activation cascade of the netherton syndrome-defective protein, LEKTI, in the epidermis: Implications for skin homeostasis

Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is the defective protein of the ichthyosiform condition Netherton syndrome (NS). Strongly expressed in the most differentiated epidermal layers, LEKTI is a serine protease inhibitor synthesized as three different high-molecular-weight precursors, which are rapidly processed into shorter fragments and secreted extracellularly. LEKTI polypeptides interact with several proteases to regulate skin barrier homeostasis as well as inflammatory and/or immunoallergic responses. Here, by combining antibody mapping, N-terminal sequencing, and site-specific mutagenesis, we defined the amino-acid sequence of most of the LEKTI polypeptides physiologically generated in human epidermis. We also identified three processing intermediates not described so far. Hence, a proteolytic cascade model for LEKTI activation is proposed. We then pinpointed the most effective fragments against the desquamation-related kallikreins (KLKs) and we proved that LEKTI is involved in stratum corneum shedding as some of its polypeptides inhibit the KLK-mediated proteolysis of desmoglein-1. Finally, we quantified the individual LEKTI fragments in the uppermost epidermis, showing that the ratios between LEKTI polypeptides and active KLK5 are compatible with a fine-tuned inhibition. These findings are relevant both to the understanding of skin homeostasis regulation and to the design of novel therapeutic strategies for NS.

The 420K LEKTI variant alters LEKTI proteolytic activation and results in protease deregulation: implications for atopic dermatitis

Lymphoepithelial Kazal-type related inhibitor (LEKTI) is a multidomain serine protease inhibitor which plays a central role in skin permeability barrier and allergy. Loss-of-function mutations in the LEKTI encoding gene SPINK5 cause Netherton syndrome, a rare and severe genetic skin disease with a profound skin barrier defect and atopic manifestations. Several studies also reported genetic association between the multifactorial disease atopic dermatitis (AD) and a frequent and non-conservative LEKTI variant, E420K, in different populations. Here, we provide evidence that the 420K variant impacts on LEKTI function by increasing the likelihood of furin-dependent LEKTI precursor cleavage within the linker region D6-D7. This results in the reversal of the cleavage priorities for LEKTI proteolytic activation and prevents the formation of the LEKTI fragment D6D9 known to display the strongest inhibitory activity against kallikrein (KLK) 5-mediated desmoglein-1 (DSG1) degradation. Using in situ and gel zymographies, we show that the modification of the subtle balance in LEKTI inhibitory fragments leads to enhanced KLK5, KLK7 and elastase-2 (ELA-2) activities in 420KK epidermis. By immunohistochemistry and western blot analyses, we found that increased epidermal protease activity correlates with reduced DSG1 protein expression and accelerated profilaggrin proteolysis. All changes determined by the presence of residue 420K within the LEKTI sequence likely contribute to defective skin barrier permeability. Remarkably, LEKTI 420KK epidermis displays an increased expression of the proallergic cytokine thymic stromal lymphopoietin (TSLP). This is the first functional evidence supporting association studies which identified the 420K LEKTI variant as a predisposing factor to AD, in combination with other genetic and environmental factors.

Therapeutic patient education in children with atopic dermatitis: position paper on objectives and recommendations

Poor adherence is frequent in patients with atopic dermatitis (AD), leading to therapeutic failure. Therapeutic patient education (TPE) helps patients with chronic disease to acquire or maintain the skills they need to manage their chronic disease. After a review of the literature, a group of multispecialty physicians, nurses, psychologists, and patients worked together during two international workshops to develop common recommendations for TPE in AD. These recommendations were structured as answers to nine frequently asked questions about TPE in AD: What is TPE and what are its underlying principles? Why use TPE in the management of AD? Who should benefit from TPE in AD? How can TPE be organized for AD? What is the assessment process for TPE in AD? What is the evidence of the benefit of TPE in AD? Who are the people involved in TPE? How should TPE be funded in dermatology? What are the limits of the TPE process?

Multicentre consensus recommendations for skin care in inherited epidermolysis bullosa

BackgroundInherited epidermolysis bullosa (EB) comprises a highly heterogeneous group of rare diseases characterized by fragility and blistering of skin and mucous membranes. Clinical features combined with immunofluorescence antigen mapping and/or electron microscopy examination of a skin biopsy allow to define the EB type and subtype. Molecular diagnosis is nowadays feasible in all EB subtypes and required for prenatal diagnosis. The extent of skin and mucosal lesions varies greatly depending on EB subtype and patient age. In the more severe EB subtypes lifelong generalized blistering, chronic ulcerations and scarring sequelae lead to multiorgan involvement, major morbidity and life-threatening complications. In the absence of a cure, patient management remains based on preventive measures, together with symptomatic treatment of cutaneous and extracutaneous manifestations and complications. The rarity and complexity of EB challenge its appropriate care. Thus, the aim of the present study has been to generate multicentre, multidisciplinary recommendations on global skin care addressed to physicians, nurses and other health professionals dealing with EB, both in centres of expertise and primary care setting.MethodsAlmost no controlled trials for EB treatment have been performed to date. For this reason, recommendations were prepared by a multidisciplinary team of experts from different European EB centres based on available literature and expert opinion. They have been subsequently revised by a panel of external experts, using an online-modified Delphi method to generate consensus.ResultsRecommendations are reported according to the age of the patients. The major topics treated comprise the multidisciplinary approach to EB patients, global skin care including wound care, management of itching and pain, and early diagnosis of squamous cell carcinoma. Aspects of therapeutic patient education, care of disease burden and continuity of care are also developed.ConclusionThe recommendations are expected to be useful for daily global care of EB patients, in particular in the community setting. An optimal management of patients is also a prerequisite to allow them to benefit from the specific molecular and cell-based treatments currently under development.

Telomere shortening and telomere position effect in mild ring 17 syndrome

BackgroundRing chromosome 17 syndrome is a rare disease that arises from the breakage and reunion of the short and long arms of chromosome 17. Usually this abnormality results in deletion of genetic material, which explains the clinical features of the syndrome. Moreover, similar phenotypic features have been observed in cases with complete or partial loss of the telomeric repeats and conservation of the euchromatic regions. We studied two different cases of ring 17 syndrome, firstly, to clarify, by analyzing gene expression analysis using real-time qPCR, the role of the telomere absence in relationship with the clinical symptoms, and secondly, to look for a new model of the mechanism of ring chromosome transmission in a rare case of familial mosaicism, through cytomolecular and quantitative fluorescence in-situ hybridization (Q-FISH) investigations.ResultsThe results for the first case showed that the expression levels of genes selected, which were located close to the p and q ends of chromosome 17, were significantly downregulated in comparison with controls. Moreover, for the second case, we demonstrated that the telomeres were conserved, but were significantly shorter than those of age-matched controls; data from segregation analysis showed that the ring chromosome was transmitted only to the affected subjects of the family.ConclusionsSubtelomeric gene regulation is responsible for the phenotypic aspects of ring 17 syndrome; telomere shortening influences the phenotypic spectrum of this disease and strongly contributes to the familial transmission of the mosaic ring. Together, these results provide new insights into the genotype-phenotype relationships in mild ring 17 syndrome.

Mucocutaneous Manifestations in Children with HIV Infection and AIDS

Abstract: Mucocutaneous diseases are more frequent in HIV/AIDS‐infected children than in the normal population. We analyze mucocutaneous disorders with atypical presentations in a large population of HIV‐infected children, with or without full‐blown AIDS, compared to a population of HIV seroreverted children. The majority of these cutaneous disorders have an infectious etiology and their frequency is related to the degree of deterioration of the immune system. Some diseases commonly observed in adults are rare in children; neoplasms are an exception.

Ichthyosis with confetti: clinics, molecular genetics and management

Ichthyosis with confetti (IWC) is an autosomal dominant congenital ichthyosis also known as ichthyosis variegata or congenital reticular ichthyosiform erythroderma. It manifests at birth with generalized ichthyosiform erythroderma or with a collodion baby picture. The erythrodermic and ichthyotic phenotype persists during life and its severity may modify. However, the hallmark of the disease is the appearance, in childhood or later in life, of healthy skin confetti-like spots, which increase in number and size with time. IWC is a very rare genodermatosis, with a prevalence <1/1,000,000 and only 40 cases reported worldwide. The most important associated clinical features include ear deformities, mammillae hypoplasia, palmoplantar keratoderma, hypertrichosis and ectropion. IWC is due to dominant negative mutations in the KRT10 and KRT1 genes, encoding for keratins 10 and keratin 1, respectively. In this context, healthy skin confetti-like spots represent “repaired” skin due to independent events of reversion of keratin gene mutations via mitotic recombination. In most cases, IWC clinical suspicion is delayed until the detection of white skin spots. Clinical features, which may represent hint to the diagnosis of IWC even before appearance of confetti-like spots, include ear and mammillae hypoplasia, the progressive development of hypertrichosis and, in some patients, of adherent verrucous plaques of hyperkeratosis. Altogether the histopathological finding of keratinocyte vacuolization and the nuclear staining for keratin 10 and keratin 1 by immunofluorescence are pathognomonic. Nevertheless, mutational analysis of KRT10 or KRT1 genes is at present the gold standard to confirm the diagnosis. IWC has to be differentiated mainly from congenital ichthyosiform erythroderma. Differential diagnosis also includes syndromic ichthyoses, in particular Netherton syndrome, and the keratinopathic ichthyoses. Most of reported IWC cases are sporadic, but familial cases with autosomal dominant mode of inheritance have been also described. Therefore, knowledge of the mutation is the only way to properly counsel the couples. No specific and satisfactory therapy is currently available for IWC. Like for other congenital ichthyoses, topical treatments (mainly emollients and keratolytics) are symptomatic and offer only temporary relief. Among systemic treatments, retinoids, in particular acitretin, improve disease symptoms in most patients. Although at present there is no curative therapy for ichthyoses, treatments have improved considerably over the years and the best therapy for each patient is always the result of both physician and patient efforts.

Lethal Netherton syndrome due to homozygous p.Arg371X mutation in SPINK5.

Here we report a lethal case of Netherton syndrome presenting with neurologic complications, hypernatremic dehydration, failure to thrive, and episodes of sepsis. Molecular analysis of the serine protease inhibitor Kazal‐type 5 gene identified a homozygous mutation (c.1111C>T, p.Arg371X). This case highlights the importance of early diagnosis to start appropriate care in a timely fashion and prevent disease complications.

Necrosis of the tongue as first symptom of Polyarteritis Nodosa (PAN): unusual presentation of a rare disease in children

Polyarteritis or panarteritis nodosa (PAN) is a necrotizing, focal segmental vasculitis that affects predominantly medium-sized arteries in many different organ systems. It is extremely rare in childhood. Involvement of the oral mucosa at diagnosis is uncommon in PAN. Here, we report a case of a pediatric patient with tongue necrosis.

Esophageal stenosis in epidermolysis bullosum: a challenge for the endoscopist.

BACKGROUND/PURPOSE Esophageal stenosis is a severe complication in dystrophic epidermolysis bullosa (EB). Endoscopic dilations may cause mucosal injury with stricture recurrence. Our aim was to describe our referral EB-center experience on safety and long-term efficacy of fluoroscopically guided balloon dilation without endoscopy. METHODS Over 14 years, 34 patients with EB, previously evaluated with barium esophagogram for dysphagia, underwent balloon esophageal dilation. Under fluoroscopy, a guide wire was introduced via a nostril into the stomach. A 12-mm pneumatic balloon, which passed over the wire, was filled using radio-opaque contrast, dilating the stricture. Orotracheal intubation was avoided. Antibiotics, dexamethasone, and proton-pump inhibitors were administered. Study approval was obtained from our ethical board. RESULTS Ninety-three dilations were performed. Seventeen patients had a single stenosis. The mean age of onset was 18 years (range, 3-47 years). Thirteen patients underwent one dilation. In 6 cases, endoscopy was necessary to visualize the esophageal lumen. Complications included cervical esophageal perforation (2) and transitory dysphagia (10). Thirty patients were feeding within 24 hours. During the follow-up, 2 patients required a gastrostomy, and 2 patients underwent fundoplication for gastroesophageal reflux disease. CONCLUSIONS Fluoroscopically guided balloon dilation in EB is a safe and well-tolerated procedure. An experienced endoscopy team is necessary in certain cases.