bromochloroacetic-acid and Epidermolysis-Bullosa

Inherited keratinizing disorders are caused by mutations in the genes encoding cornified cell envelope proteins, enzymes and their inhibitors, adhesion molecules, cytoskeletal proteins and others in the epidermis. These molecules are known to regulate differentiation, proliferation and cell adhesions. Intriguingly, some keratinizing disorders show blistering skin lesions, while some inherited blistering disorders show abnormal keratinization. Therefore, hereditary keratinizing and blistering diseases are closely related and show overlapping genetic backgrounds. In this review, we overviewed keratinizing and blistering disorders in terms of overlapping of the two disease groups. Gene mutations in desmosomal components cause striate keratoderma, Naxos disease, epidermolytic palmoplantar keratoderma and plakophilin deficiency, which first show skin fragility and blisters and later hyperkeratosis. Gene mutations in hemidesmosomal components cause various forms of epidermolysis bullosa, some of which show hyperkeratosis on the nails, palms and soles, in addition to blister formation. Diseases with gene mutations in calcium pump proteins are Darier disease and Hailey-Hailey disease, which show clinicopathological overlaps and develop both keratinizing and blistering skin lesions. Finally, gene mutations in epidermal keratins cause epidermolysis bullosa simplex, epidermolytic ichthyosis, superficial epidermolytic ichthyosis, epidermolytic palmoplantar keratoderma and pachyonychia congenita/focal palmoplantar keratoderma, which show thickening of the palms and soles with underlying blister formation. In general, responsible proteins for diseases developing both keratinizing and blistering conditions are adhesion molecules, calcium pump proteins and keratins, but not connexins, cornified cell envelop proteins, enzymes or inhibitors. It is still unknown how particular keratinizing diseases develop blisters and vice versa.

Topics: Arrhythmogenic Right Ventricular Dysplasia; Blister; Calcium; Cell Differentiation; Epidermis; Epidermolysis Bullosa; Hair Diseases; Humans; Hyperkeratosis, Epidermolytic; Keratins; Keratoderma, Palmoplantar; Mutation; Pemphigus, Benign Familial; Skin Diseases

Easy access to the organ and identification of underlying mutations in epidermolysis bullosa (EB) facilitated the first cutaneous gene therapy experiments in vitro in the mid-1990s. The leading technology was transduction of the respective cDNA carried by a retroviral vector. Using this approach, the genotypic and phenotypic hallmark features of the recessive forms of junctional EB, which are caused by loss of function of the structural proteins laminin-5 or bullous pemphigoid antigen 2/type XVII collagen of the dermo-epidermal basement membrane zone, have been corrected in vitro and in vivo using xenograft mouse models. Recently, this approach has also been shown to be feasible for the large COL7A1 gene (mutated in dystrophic EB), applying PhiC31 integrase or lentiviral vectors. Neither of these approaches has made it into a successful Phase I study on EB patients. Therefore, alternative approaches to gene correction, including modulation of splicing, are being investigated for gene therapy in EB.

Topics: Animals; Autoantigens; Carrier Proteins; Cell Adhesion Molecules; Collagen Type XVII; Cytoskeletal Proteins; Disease Models, Animal; DNA-Binding Proteins; DNA, Complementary; Dystonin; Epidermolysis Bullosa; Genetic Heterogeneity; Genetic Therapy; Genetic Vectors; Humans; Integrin beta4; Kalinin; Keratin-14; Keratinocytes; Keratins; Matrix Metalloproteinases; Mice; Mice, Nude; Nerve Tissue Proteins; Non-Fibrillar Collagens; Protease Inhibitors; RNA Splicing; RNA, Catalytic; Telomerase

Epidermolysis bullosa (EB), a heterogenous group of genodermatoses, is characterized by fragility and blistering of the skin associated with extracutaneous manifestations. Based on clinical severity, constellation of the phenotypic manifestations, and the level of tissue separation within the cutaneous basement membrane zone (BMZ), EB has been divided into distinct subcategories. Traditionally, these include the simplex, junctional, and dystrophic forms of EB, and recently attention has been drawn to hemidesmosomal variants demonstrating tissue separation at the level of the hemidesmosomes. Specific mutations in ten distinct genes expressed within the cutaneous BMZ have been delineated in >500 families with different variants of EB. The types of mutations, their positions along the affected genes, and their consequences at the mRNA and protein levels provide explanation for the phenotypic variability and genetic heterogeneity of this group of genodermatoses. Elucidation of mutations in different forms of EB has direct translational applications for improved diagnosis and molecularly based classification with prognostic implications as well as for genetic counseling and DNA-based prenatal testing in families with EB.

Topics: Basement Membrane; DNA Mutational Analysis; Epidermolysis Bullosa; Genotype; Humans; Keratins; Models, Biological; Mutation; Phenotype

The outer part of the skin, the epidermis, is specialized to protect the human body from its environment. Because of the high levels of physical stress experienced by the human hand in everyday use, the epidermis of the hand is especially toughened. In particular, the epidermis of the palm is highly specialized to resist mechanical trauma. Like the epidermis, the nails are composed of specialized epithelial cells and are especially strong. In recent years it has become apparent that the physical strength of epithelial cells comes from the keratin cytoskeleton--a dense meshwork of filaments extending throughout the cytoplasm. Keratins are a large family of intermediate filament proteins encoded by more than 50 distinct genes in humans. These different keratin genes are expressed in well-defined combinations in specific epithelial tissues. Several keratin genes are expressed in palmoplantar epidermis and in the stratified epithelia of the nail bed. Genetic mutations in these genes lead to fragility of these tissues and result in a range of genetic disorders characterized by blistering and thickening of palm and sole skin and/or nails. Study of these diseases has shed new light on the vital structural role of keratins in maintaining the integrity of epithelial cells.

Topics: Epidermolysis Bullosa; Fingers; Humans; Keratins; Keratoderma, Palmoplantar; Mutation; Nail Diseases; Skin

A large number of mutations in keratin genes underlie inherited tissue fragility disorders of epithelia. The genotype-phenotype correlations emerging from these studies provide a rich source of information about the function of keratins that would have taken decades to achieve by a purely transgenic approach. Human disease studies are being supplemented by engineered mouse mutant studies, which give access to the effects of genetic alterations unlikely to occur naturally. Evidence is emerging that the great diversity of keratins might be required to enable cells to adapt their structure in response to different signalling pathways.

Topics: Animals; Epidermis; Epidermolysis Bullosa; Epithelium; Genotype; Humans; Hyperkeratosis, Epidermolytic; Keratins; Mice; Mice, Knockout; Models, Genetic; Mutagenesis; Mutation; Phenotype

The epidermis of skin and the oral mucosa are highly specialized stratified epithelia that function to protect the body from physical and chemical damage, infection, dehydration, and heat loss. To maintain this critical barrier, epithelial tissues undergo constant renewal and repair. Epithelial cells (keratinocytes) undergo a program of terminal differentiation, expressing a set of structural proteins, keratins, which assemble into filaments and function to maintain cell and tissue integrity. Two types of cell adhesion structures, desmosomes and hemidesmosomes, function to glue keratinocytes to one another and to the basement membrane, and connect the keratin cytoskeleton to the cell surface. Keratinizing epithelia such as the epidermis and oral gingiva that have to withstand severe physical and chemical forces produce a toughened structure, the cornified cell envelope. This envelope is a major component of the epithelial barrier at the tissue surface. This article summarizes our current understanding of the structure and function of these different cellular components and discusses various genetic and acquired diseases that alter tissue integrity and barrier function. We also highlight recent work demonstrating how loss or attenuation of certain proteases can lead to early onset periodontitis and tooth loss as well as other epithelial abnormalities.

Topics: Autoimmune Diseases; Cadherins; Desmosomes; Epidermolysis Bullosa; Epithelial Cells; Humans; Keratins; Mouth Mucosa; Mutation

Topics: Collagen; Diagnosis, Differential; Epidermolysis Bullosa; Humans; Keratins; Laminin; Mutation

Great progress has recently been made in understanding the molecular basis of various heritable skin diseases. A prototype of such conditions is epidermolysis bullosa (EB), a heterogeneous group of mechano-bullous disorders characterized by fragility of the skin and other specialized epithelia. Blistering of the skin in EB results either from fragility of epidermal cells or from defective attachment of the epidermis to the underlying dermis, because of genetic lesions within molecules of the basement-membrane zone at the dermal-epidermal junction. Distinct mutations have been discovered in ten different genes encoding the structural components within this layer. The combinations and the types of mutations, as well as their positions in the altered gene products, collectively reflect the phenotypic variability observed in this group of heritable skin diseases.

Topics: Collagen; Epidermolysis Bullosa; Epidermolysis Bullosa Simplex; Genetic Heterogeneity; Humans; Intermediate Filament Proteins; Keratins; Laminin; Mutation; Phenotype; Plectin

Spectacular success has recently been made towards elucidation of the molecular basis of various forms of epidermolysis bullosa (EB), a group of heritable blistering skin diseases. The information derived from these studies has already had a profound impact in terms of precise diagnosis and classification, early prenatal prediction of the phenotype and genetic counseling in families at risk for recurrence. This review highlights recent progress made in defining the molecular basis of junctional and dystrophic forms of EB and the genotype/phenotype relationships established from these studies. Extensive molecular studies, such as the ones captured in this review, form a foundation for the rational design of gene therapies to counteract these conditions in the future.

Topics: Amino Acid Sequence; Animals; Antigens, CD; Autoantigens; Basement Membrane; Carrier Proteins; Codon; Collagen; Collagen Type XVII; Cytoskeletal Proteins; Desmosomes; DNA Mutational Analysis; Dystonin; Epidermolysis Bullosa; Genetic Heterogeneity; Genetic Therapy; Genotype; Humans; Integrin beta4; Keratins; Laminin; Mice; Mice, Knockout; Molecular Sequence Data; Muscular Dystrophies; Mutation; Nerve Tissue Proteins; Non-Fibrillar Collagens; Sequence Deletion; Skin

In the past 5 years enormous progress have been made in our understanding of the molecular basis for a number of inherited skin diseases characterized by easy blistering of the skin and the mucous membranes after minor physical trauma. This increased fragility of the skin or its appendages is due to molecular defects in genes coding for different intra- and extracellular structural proteins which are responsible for mechanical strength at their sites of expression. These diseases encompass the group of epidermolysis bullosa and disorders of cornification such as bullous forms of ichthyosis, palmoplantar keratoderma, and pachyonychia congenita. On the basis of clinical, morphological, and ultrastructural observations the epidermolysis bullosa group has been divided into three major categories. In epidermolysis bullosa simplex blister formation appears within the basal cell layer of the epidermis, and many mutations have been found in the genes of keratin 5 and 14 which are both expressed in basal keratinocytes. Epidermolytic hyperkeratosis leads to an epidermal separation in the suprabasal cell layers. In these patients numerous point mutations have now been described in the suprabasally expressed genes of keratin 1 and 10. In ichthyosis bullosa of Siemens blisters occur in the more upper suprabasal epidermis coincidental with the expression of keratin 2e, and mutations have been detected in the corresponding gene. In epidermolytic palmoplantar hyperkeratosis the suprabasal epidermal splitting is restricted to palms and soles of the patient. In keratin 9, which reveals such an exclusive expression pattern, molecular defects have indeed been recognized. Most recently in two different clinical subtypes of pachyonychia congenita, which is characterized by defective nails and focal palmoplantar hyperkeratosis, point mutations have been found in the genes coding for keratins 6, 16, and 17. In junctional epidermolysis bullosa the separation takes place within the dermal-epidermal basement membrane at the level of the lamina lucida, and mutations have been found in three genes coding for different laminin chains, in the beta4 gene of alpha6beta4 integrin, and in the gene of collagen XVII. In dystrophic epidermolysis bullosa the tissue separation occurs beneath the basement membrane within the papillary dermis at the level of the anchoring fibrils, and several mutations have been identified in the collagen VII gene. The rapid unraveling of molecular defects in the

Topics: Antigens, CD; Epidermolysis Bullosa; Humans; Integrin beta4; Keratins; Laminin; Mutation; Skin

Intermediate filaments are major structural proteins encoded by a large multigene family. Their tissue-specific expression makes them important in studies of development, differentiation and pathology. Most intermediate filaments are keratins; recent discoveries of keratin mutations in a range of genetic skin disorders have clarified their role as providing essential structural support for cells in different physical settings.

Topics: DNA; Epidermolysis Bullosa; Genetic Code; Genetic Linkage; Humans; Intermediate Filaments; Keratins; Mutation; Protein Structure, Tertiary

Recent developments of the molecular and cell biology of the cutaneous basement membrane zone have greatly advanced our understanding of the pathomechanisms underlying skin blistering disorders. The heritable blistering diseases, the epidermolysis bullosa group, have been investigated as model diseases. Defects in genes coding for the structural proteins of the basement membrane zone have been defined in some EB subtypes and abnormal expression of the structural proteins in others. In vitro studies utilizing cutaneous cells derived from epidermolysis bullosa skin have helped to understand the pathogenetic pathways that lead from the mutation to the symptom, skin blistering. The data accumulated from analyses of the genetic disorders will yield indirect information on the normal physiology of the skin and be highly relevant for discerning the etiopathogenesis of acquired blistering diseases and for dermal-epidermal interactions required for reparative processes, such as wound healing.

Topics: Basement Membrane; Collagen; Epidermolysis Bullosa; Genes; Humans; Keratins; Skin

Topics: Animals; Epidermolysis Bullosa; Gene Expression; Humans; Hyperkeratosis, Epidermolytic; Intermediate Filaments; Keratins; Keratoderma, Palmoplantar, Diffuse; Mice; Mice, Transgenic; Point Mutation; Skin Diseases

Inherited epidermolysis bullosa (EB) includes three main types depending on the precise ultrastructural level at which the split responsible for the blistering occurs; 1) simplex EB (SEB) located at the level of the basal cells; 2) junctional EB (JEB) located in the lamina lucida; 3) dystrophic EB (DEB) located in the dermis below the lamina densa at the level of the anchoring fibrils. The authors review the major recent progresses which have led to the identification of the genes and of several molecular defects in these three types, such as: mutations of the genes of keratins 5 and 14 in SEB, molecular defects in the gamma 2 chain gene of nicein/kalinin coding for the anchoring fibrils in JEB, abnormalities of the collagen VII gene coding for the anchoring fibrils in DEB. These data allow to consider a classification of EB based on molecular defects. They also have important consequences for genetic counselling and prenatal diagnosis for the families presenting an affected child.

Topics: Cell Adhesion Molecules; Collagen; Epidermolysis Bullosa; Genetic Counseling; Humans; Infant, Newborn; Kalinin; Keratins; Molecular Biology; Mutation

Recent research into the molecular basis of epidermolysis bullosa has provided a unique insight into a variety of mechanisms in normal cell biology, such as cell-matrix interactions, and has uncovered an excellent model for studies on keratin intermediate filaments. The simplex forms of epidermolysis bullosa are caused by mutations in the genes for the basal epidermal keratins, K5 and K14. Most mutations affect highly conserved parts of the molecules, illustrating their importance in normal keratin filament assembly and integrity. Mutations in corresponding regions of the differentiation-associated keratins, K1 and K10 can also occur in epidermolytic ichthyosis. Both recessive and dominant forms of dystrophic epidermolysis bullosa result from mutations in an anchoring fibril collagen gene, COL7A1. Junctional epidermolysis bullosa is caused by mutations in the genes encoding different chains of the novel laminin isoform, nicein/kalinin, also known as laminin 5, which is associated with the anchoring filament-hemidesmosome complex of the basement membrane zone. These recent findings strengthen the evidence for the role of nicein/kalinin and type VII collagen in adherence and stabilization of the dermo-epidermal junction.

Topics: Animals; Collagen; Epidermolysis Bullosa; Humans; Keratins; Mutation

Clues from clinicopathologic studies of epidermolysis bullosa simplex (EBS) and epidermolytic hyperkeratosis (EH) have implicated abnormalities in keratin filaments as possibly underlying the pathogenesis of these diseases. Multiple avenues of study have now converged, which confirm this hypothesis.. The clinical spectrum of EBS and EH is reviewed together with classic histologic, electron microscopic, and immuno-electron microscopic studies. Linkage analyses have shown in EBS and EH that the disease traits are linked to the keratin gene clusters on chromosomes 12 and 17. Transgenic mice bearing mutations or deletions in genes coding for basal cell keratin K14 express the phenotype of EBS, and transgenic mice bearing abnormal K1/K10 genes resemble EH. Increasing numbers of point mutations in the human keratin genes have been found in both sporadic and familial cases of EBS in keratins 5/14 and EH in keratins K1/K10 genes, respectively, particularly in highly conserved subdomains of the keratin proteins.. The recent and rapid progress in understanding the molecular biology of EBS and EH will also enhance knowledge about intermediate filament structure and function. Further studies of the effects of these mutations on the control of keratinocyte growth and differentiation are required. They will lead the way to rational pharmacologic or gene therapy.

Topics: Epidermis; Epidermolysis Bullosa; Genes; Humans; Hyperkeratosis, Epidermolytic; Keratins; Mutation

The past year has been extremely fruitful for research on intermediate filaments in general, and keratins in particular. Unprecedented progress has been made in our understanding of the structural requirements for keratin filament assembly and network formation, the dynamism characterizing keratin filaments, their function, and implication in human genetic disorders primarily affecting the skin. These exciting findings have several implications for future research.

Topics: Amino Acid Sequence; Animals; Disease Models, Animal; Epidermolysis Bullosa; Humans; Hyperkeratosis, Epidermolytic; Keratins; Mice; Mice, Transgenic; Molecular Sequence Data; Multigene Family; Mutagenesis; Polymorphism, Genetic; Prevalence; Protein Processing, Post-Translational; Viral Proteins

Blisters following minor trauma characterize epidermolysis bullosa, a group of hereditary diseases of the skin. In the simplex type, epidermal basal cells are fragile, and mutations of genes encoding keratin intermediate filament proteins underlie that fragility. In the dystrophic types, the causative mutation appears to be in the gene encoding type VII collagen, which is the major component of anchoring fibrils. These recent findings afford solid evidence that at least one function of the cytoskeletal intermediate filament network is the provision of mechanical stability and that anchoring fibrils indeed do anchor the epidermis to the underlying dermis.

Topics: Chromosomes, Human, Pair 12; Chromosomes, Human, Pair 17; Cytoskeleton; Epidermolysis Bullosa; Humans; Keratins; Multigene Family; Skin

Topics: Basement Membrane; Collagen; Epidermolysis Bullosa; Genetic Linkage; Genetic Therapy; Humans; Keratins; Skin; Skin Diseases, Vesiculobullous

Topics: Biopsy; Epidermis; Epidermolysis Bullosa; Humans; Keratins; Pemphigoid, Bullous; Pemphigus; Peptide Hydrolases; Protease Inhibitors; Skin Diseases, Vesiculobullous

Topics: Acrodermatitis; Amino Acid Metabolism, Inborn Errors; Basal Cell Nevus Syndrome; Epidermolysis Bullosa; Hair Diseases; Humans; Ichthyosis; Keratins; Keratosis; Neurofibromatosis 1; Psoriasis; Refsum Disease; Skin; Skin Diseases; Skin Neoplasms; Tuberous Sclerosis; Tyrosine; Warts; Xeroderma Pigmentosum

Missense mutations in keratin 5 and 14 genes cause the severe skin fragility disorder epidermolysis bullosa simplex (EBS) by collapsing of the keratin cytoskeleton into cytoplasmic protein aggregates. Despite intense efforts, no molecular therapies are available, mostly due to the complex phenotype of EBS, comprising cell fragility, diminished adhesion, skin inflammation and itch.. We extensively characterized KRT5 and KRT14 mutant keratinocytes from patients with severe generalized EBS following exposure to the chemical chaperone 4-phenylbutyrate (4-PBA).. 4-PBA diminished keratin aggregates within EBS cells and ameliorated their inflammatory phenotype. Chemoproteomics of 4-PBA-treated and untreated EBS cells revealed reduced IL1β expression- but also showed activation of Wnt/β-catenin and NF-kB pathways. The abundance of extracellular matrix and cytoskeletal proteins was significantly altered, coinciding with diminished keratinocyte adhesion and migration in a 4-PBA dose-dependent manner.. Together, our study reveals a complex interplay of benefits and disadvantages that challenge the use of 4-PBA in skin fragility disorders.

Topics: Animals; Apoptosis; Biomarkers; Biopsy; Cell Adhesion; Cell Communication; Cell Line; Cytoskeleton; Disease Models, Animal; Epidermolysis Bullosa; Extracellular Matrix; Humans; Immunohistochemistry; Keratinocytes; Keratins; Mice; Phenotype; Phenylbutyrates; Protein Transport; Proteome; Proteomics; Signal Transduction; Skin

The discovery of the causative link between keratin mutations and a growing number of human diseases opened the way for a better understanding of the function of the whole intermediate filament families of cytoskeleton proteins. This chapter describes analytical approaches to identification and interpretation of the consequences of keratin mutations, from the clinical and diagnostic level to cells in tissue culture. Intermediate filament pathologies can be accurately diagnosed from skin biopsies and DNA samples. The Human Intermediate Filament Database collates reported mutations in intermediate filament genes and their diseases, and can help clinicians to establish accurate diagnoses, leading to disease stratification for genetic counseling, optimal care delivery, and future mutation-aligned new therapies. Looking at the best-studied keratinopathy, epidermolysis bullosa simplex, the generation of cell lines mimicking keratinopathies is described, in which tagged mutant keratins facilitate live-cell imaging to make use of today's powerful enhanced light microscopy modalities. Cell stress assays such as cell spreading and cell migration in scratch wound assays can interrogate the consequences of the compromised cytoskeletal network. Application of extrinsic stresses, such as heat, osmotic, or mechanical stress, can enhance the differentiation of mutant keratin cells from wild-type cells. To bring the experiments to the next level, 3D organotypic human cultures can be generated, and even grafted onto the backs of immunodeficient mice for greater in vivo relevance. While development of these assays has focused on mutant K5/K14 cells, the approaches are often applicable to mutations in other intermediate filaments, reinforcing fundamental commonalities in spite of diverse clinical pathologies.

Topics: Animals; Epidermis; Epidermolysis Bullosa; Humans; Intermediate Filaments; Keratins; Mutation

Epidermolysis bullosa (EB) describes a number of genetically inherited conditions which cause skin fragility and minor trauma leading to skin damage, skin loss and wounding. Owing to the fragility of the skin and requirement for frequent dressing changes, at present, the optimal dressing(s) is not clear. Our objective was to assess the use of a keratin gel in the management of wounds in patients with different forms of EB.. We treated patients with different types of EB and a range of wounds with a novel keratin gel. In a convenience sample of consecutive patients, we introduced the keratin gel into their treatment regimen maintaining other aspects of their care.. Patients reported faster healing and more resilient healed skin. Of the ten patients treated in this pilot study, six found the gel effective; two found it ineffective; and in two patients, it caused itching leading to discontinuation of the treatment.. The results of this case study series suggest that keratin gel can be useful in the management of EB and are consistent with previous published experiences.

Topics: Adolescent; Bandages; Child; Child, Preschool; Disease Management; Epidermolysis Bullosa; Female; Gels; Humans; Infant; Keratins; Male; Pilot Projects; Skin Abnormalities; Treatment Outcome; Wound Healing

Epidermolysis bullosa (EB) was diagnosed in eight calves from four farms in the United Kingdom on the basis of clinical, histological and ultrastructural findings. In three affected herds, pedigree Simmental bulls had been mated with Simmental-cross cows. In a fourth herd two Holstein-Friesian calves were affected. Lesions included multifocal erosion and ulceration of the hard and soft palates, tongue, nares and gingiva, with onychomadesis (dysungulation). There was alopecia, erosion and crusting of the coronets, pasterns, fetlocks, carpi, hocks, flanks and axillae. Histopathological findings included segmental separation of full thickness epidermis from the dermis, with formation of large clefts containing eosinophilic fluid, extravasated red blood cells and small numbers of neutrophils. Follicular and interfollicular areas of skin were affected, with clefts extending around hair follicles and sometimes involving whole follicles. Ultrastructurally, there was evidence of vacuolar change within basal keratinocytes, corresponding to areas of histological clefting. Preliminary genetic screening of the candidate keratin genes (bKRT5 and bKRT14) has excluded mutations of these as the cause of this condition.

Topics: Alopecia; Animals; Cattle; Epidermis; Epidermolysis Bullosa; Female; Keratinocytes; Keratins; Mutation; Nail Diseases; Pedigree; Pregnancy; Skin; United Kingdom

Topics: Epidermolysis Bullosa; Humans; Keratins; Mutation; Stem Cell Transplantation

Basal layers of stratified epithelia express keratins K5, K14, and K15, which assemble into intermediate filament networks. Mutations in K5 or K14 genes cause epidermolysis bullosa simplex (EBS), a disorder with blistering in the basal layer due to cell fragility. Nonkeratinizing stratified epithelia, e.g., in the esophagus, produce more keratin K15 than epidermis, which alleviates the esophageal symptoms in patients with K14 mutations. Hypothesizing that increasing the cellular content of K15 could compensate for the mutant K14 and thus ease skin blistering in K14 EBS patients, we cloned the promoter of the K15 gene and examined its transcriptional regulation. Using cotransfection, gel mobility shifts, and DNase I footprinting, we have identified the regulators of K15 promoter activity and their binding sites. We focused on those that can be manipulated with extracellular agents, transcription factors C/EBP, AP-1, and NF-kappaB, nuclear receptors for thyroid hormone, retinoic acid, and glucocorticoids, and the cytokine gamma interferon (IFN-gamma). We found that C/EBP-beta and AP-1 induced, while retinoic acid, glucocorticoid receptors, and NF-kappaB suppressed, the K15 promoter, along with other keratin gene promoters. However, the thyroid hormone and IFN-gamma uniquely and potently activated the K15 promoter. Using these agents, we could boost the amounts of K15 in human epidermis. Our findings suggest that treatments based on thyroid hormone and IFN-gamma could become effective agents in therapy for patients with EBS.

Topics: Animals; Base Sequence; Cells, Cultured; Epidermal Cells; Epidermis; Epidermolysis Bullosa; Gene Expression Regulation; Glucocorticoids; Humans; Interferon-gamma; Keratin-14; Keratin-15; Keratins; Molecular Sequence Data; Promoter Regions, Genetic; Receptors, Glucocorticoid; Receptors, Retinoic Acid; Receptors, Thyroid Hormone; Thyroid Hormones; Transcription Factors; Transcription, Genetic; Tretinoin

Recessive epidermolysis bullosa simplex (REBS) is characterized by generalized cutaneous blistering in response to mechanical trauma. This results from fragility of the basal keratinocytes that lack keratin tonofilaments because of homozygote null mutation in the keratin 14 gene. REBS patients display in addition focal dyskeratotic skin lesions with histology of epidermolytic hyperkeratosis (EHK) and tonofilament clumping in the suprabasal layers of the epidermis. In this study we examined whether it is possible to mimic in vitro the bullous and dyskeratotic cellular phenotype. For this purpose, fibroblasts from nondyskeratotic (K14-/-) and dyskeratotic (K14-/-) skin of a REBS patient and fibroblasts from a healthy donor (K14+/+) were isolated and incorporated into collagen matrices. Subsequently, fresh biopsies originating from the nondyskeratotic and dyskeratotic skin of the patient and from a healthy donor were placed onto the collagen matrices and cultured at the air-liquid interface. Epidermal morphogenesis was evaluated on the basis of tissue morphology and the expression of a series of keratins. The results of the present study indicate that basal cell vacuolization in REBS can be mimicked in vitro but not the EHK. Fibroblasts seem to play an important regulatory role in establishing the REBS phenotype. These findings suggest that wild-type fibroblasts may enhance the stability of K14-/- keratinocytes in vitro.

Topics: Biopsy; Cell Culture Techniques; Cells, Cultured; Epidermis; Epidermolysis Bullosa; Fibroblasts; Genes, Recessive; Humans; Immunohistochemistry; Keratin-14; Keratinocytes; Keratins; Microscopy, Fluorescence; Mutation; Phenotype

Topics: Animals; Autoantigens; Base Sequence; Carrier Proteins; CHO Cells; Collagen; Collagen Type XVII; Cricetinae; Cytoskeletal Proteins; DNA; DNA Repair; Dystonin; Epidermolysis Bullosa; Genetic Therapy; Homozygote; Humans; Keratin-14; Keratinocytes; Keratins; Microscopy, Fluorescence; Molecular Sequence Data; Mutation; Nerve Tissue Proteins; Non-Fibrillar Collagens; Oligonucleotides; Point Mutation; RNA

Epidermolytic palmoplantar keratoderma (EPPK, MIM #144200) is an autosomal dominant disorder in which hyperkeratosis confined to the palms and soles is characterized histologically by cytolysis of suprabasal keratinocytes. Mutations in the keratin 9 gene (KRT9), a type 1 keratin expressed exclusively in the suprabasal keratinocytes of palmoplantar epidermis, have previously been demonstrated in this disorder. Here, we have studied four Northern Irish kindreds presenting with EPPK. By direct sequencing of polymerase chain reaction products, heterozygous missense mutations in exon 1 of KRT9 were detected in all the families. These included a novel mutation M156T; as well as M156V in two kindreds; and R162Q in the remaining family. All mutations were confirmed by reverse strand sequencing and restriction enzyme analysis. The point prevalence of EPPK in Northern Ireland was found to be 4.4 per 100,000. To date, all reported EPPK mutations occur in the helix initiation motif at the start of the central coiled-coil rod domain of K9.

Topics: Epidermolysis Bullosa; Humans; Keratins; Keratoderma, Palmoplantar; Mutation, Missense; Northern Ireland

Topics: Epidermolysis Bullosa; Humans; Keratins; Mutation; Skin Diseases, Vesiculobullous

Kindler syndrome is a genodermatosis that combines clinical features of hereditary epidermolysis bullosa and poikiloderma congenitale. The ultrastructural level of blister formation has not been well characterized.. Two brothers with Kindler syndrome had a history of primarily acral blistering since infancy as well as photosensitivity. Blister formation was found through the basal layer. Marked tonofilament clumping was found in intact keratinocytes adjacent to the blisters. The younger brother (aged 21 years) had actinic keratoses, which have not been previously described in Kindler syndrome.. The findings of basal layer separation in both spontaneous and induced blisters in Kindler syndrome suggest this is the true level of blister formation. The finding of actinic keratoses in a young patient with Kindler syndrome suggests that some patients may be at increased risk for early solar-induced skin disease. The presence of clumped tonofilaments in keratinocytes adjacent to blistered areas suggests an abnormality of keratin 5 or 14 could be present and may play a role in blister formation in patients with Kindler syndrome.

Topics: Adult; Blister; Epidermolysis Bullosa; Humans; Intermediate Filaments; Keratinocytes; Keratins; Keratosis; Male; Photosensitivity Disorders; Rothmund-Thomson Syndrome; Skin; Syndrome

Topics: Actin Cytoskeleton; Desmosomes; Epidermolysis Bullosa; Humans; Intercellular Junctions; Keratins; Pemphigus; Skin

Electron microscopy of skin provides diagnostic criteria for distinguishing the simplex, junctional, and dystrophic forms of inherited epidermolysis bullosa (EB). The plane of cleavage in blister formation indicates the localization of structural weakness within the epidermis and basement membrane zone, and, together with ultrastructural changes in affected skin, these are clues to the underlying genetic bases for these disorders. Skin biopsy specimens from individuals with EB were evaluated by electron microscopy to identify structural changes and determine the subtype of EB.. Discrete, circumscribed clumps of keratin filaments present in the basal keratinocytes are pathognomonic for EB simplex Dowling-Meara. These and other observations of keratin filament disruption have led to the identification of mutations in keratin genes in Dowling-Meara and Koebner forms of EB simplex. Changes in the density and structure of anchoring fibrils and the relative amount of type VII collagen detected by immunostaining of the dermoepidermal junction in dystrophic EB have led to sequencing of mutations in the type VII collagen gene. Although mutations in junctional EB have not been reported, findings of structural alterations in hemidesmosomes and immunohistochemical studies of kalinin (BM600 and epiligrin), and in junctional EB with pyloric atresia alterations in the integrin alpha 6 beta 4, indicate molecules involved in basal keratinocyte adhesion to the basement membrane that are candidate genes for junctional EB.. Electron microscopy of skin when correlated with mutations in EB will help us understand the significance of these structural molecules in normal skin and the pathogenesis of EB.

Topics: Antigens, Surface; Basement Membrane; Cell Adhesion Molecules; Cell Membrane; Collagen; Cytoskeleton; Desmosomes; Epidermis; Epidermolysis Bullosa; Epidermolysis Bullosa Dystrophica; Epidermolysis Bullosa Simplex; Epidermolysis Bullosa, Junctional; Humans; Integrin alpha6beta4; Integrins; Kalinin; Keratinocytes; Keratins; Langerhans Cells; Melanocytes; Microscopy, Electron; Skin

Epidermolysis bullosa simplex (EBS) is a group of epidermal blistering diseases almost invariably transmitted as a dominant trait, which has recently been shown to arise from mutations in keratins 14 and 5 (K14 and K5). We describe a family with recessive EBS in which the disease is tightly linked to the substitution of the highly conserved glutamic acid-144 to alanine in the first helical segment of the rod domain of keratin 14. In contrast, linkage with keratin 5 was excluded. The loss of an ionic interaction with keratin 5 is likely to affect K14-K5 heterodimer formation. Our data suggest that this mutation underlies EBS in our family, and that mutations in keratin genes may impair the mechanical integrity of basal keratinocytes in a recessive as well as dominant fashion.

Topics: Alanine; Amino Acid Sequence; Base Sequence; Cells, Cultured; Conserved Sequence; DNA Primers; Epidermolysis Bullosa; Female; Genes, Dominant; Genes, Recessive; Genetic Linkage; Glutamic Acid; Humans; Keratinocytes; Keratins; Macromolecular Substances; Male; Molecular Sequence Data; Polymerase Chain Reaction; Protein Structure, Secondary; Skin

Epidermolysis bullosa simplex (EBS) is a dominantly inherited genodermatosis characterized by intraepidermal blister formation. Recent reports have suggested that EBS mutations may relate to keratin abnormalities. In this study, we conducted RFLP analyses to test the hypothesis that EBS is linked to one of the keratin gene clusters on chromosome 12 or chromosome 17. Although these keratin gene loci are not defined by RFLPs, several mapped RFLPs in the same chromosomal regions could be tested for linkage. A large EBS family with 14 affected and 12 unaffected individuals in three generations was analyzed for RFLP inheritance. Within this family there was no evidence for linkage of the EBS mutation to markers on chromosome 17q. However, there was evidence for close linkage to D12S17 located on chromosome 12q, with a maximum LOD score of 5.55 at theta = 0. Mapping of this mutation to chromosome 12 defines an EBS locus distinct from both EBS1 (Ogna) and EBS2 (Koebner), which are on chromosomes 8 and 1, respectively. Further mapping will determine whether this EBS locus on chromosome 12 resides within the keratin gene cluster at 12q11-q13.

Topics: Chromosome Mapping; Chromosomes, Human, Pair 12; Chromosomes, Human, Pair 17; Epidermolysis Bullosa; Female; Genetic Linkage; Humans; Keratins; Male; Multigene Family; Mutation; Pedigree; Polymorphism, Restriction Fragment Length

Topics: Animals; Collagen; Epidermis; Epidermolysis Bullosa; Humans; Keratins; Mice; Mice, Transgenic

Epidermolysis bullosa represents a grouping of inherited skin diseases characterized by epidermal fragility and frequently wounded skin. The recessive dystrophic subtype of epidermolysis bullosa (RDEB) is characterized by extensive dermal scarring after healing of repeated epidermal injuries and by an unusually high incidence of squamous cell carcinoma occurring in chronically wounded skin. In contrast, the simplex form of epidermolysis bullosa usually heals without scarring and does not predispose to malignant neoplasms of the skin. The differences in scarring and the neoplastic potential of these two forms of epidermolysis bullosa prompted us to investigate growth activation and differentiation characteristics in epidermal keratinocytes in individuals with these disorders. The expression of filaggrin, involucrin, cytokeratins, and the growth activation marker psi-3 was examined by immunohistochemistry in skin biopsy specimens from four individuals with epidermolysis bullosa simplex and six individuals with RDEB. Previous experiments using this technique have demonstrated that these antibodies are good markers for identifying growth-activated keratinocytes in wounded and hyperplastic epidermis. All biopsy specimens of healed wounds in skin from patients with RDEB showed epidermis that reacted with antibodies to filaggrin, involucrin, specific cytokeratins, and psi-3 in a growth-activated pattern. This growth-activated phenotype was maintained in keratinocytes from previously wounded skin that had been healed for more than 2 years. The RDEB growth-activated phenotype detected by immunohistochemistry was not associated with microscopically detectable epidermal hyperplasia. In contrast, all cases of epidermolysis bullosa simplex examined showed an epidermal phenotype similar to that of keratinocytes in normal skin. Thus, healing with dermal scar formation in RDEB is associated with a persistent growth-activated immunophenotype of epidermal keratinocytes. This chronic growth activation state or failure of cells to differentiate in a normal fashion may be directly linked to the high incidence of squamous cell cancers in individuals with RDEB.

Topics: Adolescent; Adult; Antigens; Carcinoma, Squamous Cell; Epidermis; Epidermolysis Bullosa; Female; Filaggrin Proteins; Humans; Infant; Infant, Newborn; Intermediate Filament Proteins; Keratinocytes; Keratins; Male; Middle Aged; Protein Precursors; Retrospective Studies; Skin Neoplasms

Distinctive abnormality in the organization of keratin intermediate filaments (KIFs) was found for the first time in cultured epidermal keratinocytes from two patients with hereditary epidermolysis bullosa simplex (EBS), which showed cleavages above the basement membrane zone due to the fragility of basal cells. KIFs in EBS keratinocytes revealed an irregular radial arrangement composed of sparse but thick KIF bundles. Furthermore, these KIF bundles in many cells changed into numerous ball-like keratin aggregates and disappeared beyond these keratin aggregates in the peripheral cytoplasm. Electron microscopy of cultured EBS keratinocytes showed that many ball-like structures consisting of fine filaments or granules or homogeneous substances were scattered in the peripheral regions of the cell attaching to the dish, and intermediate filaments appeared to be emanating from or surrounding the structures. These ball-like keratin aggregates have never been observed in normal human keratinocytes.

Topics: Adult; Child; Cytoskeleton; Epidermis; Epidermolysis Bullosa; Female; Fluorescent Antibody Technique; Humans; Intermediate Filaments; Keratins; Microscopy, Electron

A patient with epidermolysis bullosa simplex with mottled pigmentation is described. Clinical features include blistering of the skin, especially of the extremities; healing without scars; slight atrophy of the skin; and striking mottled pigmentation of the trunk. Histologic examination of a biopsy specimen from freshly frictioned, clinically uninvolved skin indicated a split inside the basal keratinocytes, focal hyperpigmentation of the basal cells, and pigment incontinence without an inflammatory infiltrate. Indirect immunofluorescence demonstrated focal discontinuity of the basement membrane zone. Electron microscopic examination revealed basal keratinocytes with few intact intracellular organelles, aggregated tonofilaments, and subnuclear splitting with the basal parts of the cells adhering to the basement membrane. Both normal basement membrane and zones of irregular and interrupted structures were seen. Hemidesmosomes and anchoring fibrils appeared to be normal.

Topics: Adolescent; Atrophy; Basement Membrane; Biopsy; Epidermis; Epidermolysis Bullosa; Fluorescent Antibody Technique; Humans; Keratins; Male; Microscopy, Electron; Pigmentation Disorders

The Dowling-Meara variant of epidermolysis bullosa simplex (EBS) is characterized microscopically by clumping of the keratin tonofilaments within areas of incipient blistering, thereby raising the possibility that an abnormality of the keratin cytoskeleton might underlie blister formation in this condition. In order to investigate keratin expression in Dowling-Meara EBS, the staining profile of a panel of antikeratin monoclonal antibodies was examined in perilesional skin from 5 affected subjects, using a standard immunoperoxidase technique. Normal labelling characteristics were demonstrated by antibodies identifying keratins of the basal and suprabasal compartments of normal interfollicular epidermis and of simple epithelia (keratin 19). In addition, a keratin expressed in hyperproliferative epidermal states was shown to be absent. The results suggest that the profile of keratin synthesis is normal in Dowling-Meara EBS and that the tonofilament clumping may be, therefore, the result of a post synthetic modification of keratin molecules.

Topics: Adult; Epidermis; Epidermolysis Bullosa; Humans; Immunoenzyme Techniques; Keratins; Skin; Staining and Labeling

There are at least six variants of junctional epidermolysis bullosa (JEB). About 20 cases of the generalized atrophic benign variant of JEB (GABEB) have been previously reported. We present an additional case of GABEB, occurring in a 14-year-old girl. Generalized cutaneous blisters occurred since birth and healed without severe scarring or milia, but with slight atrophy. In addition, mucous membrane involvement and hair, nail and tooth abnormalities were found. Electron microscopic examination showed a cleavage within the lamina lucida and the presence of numerically and structurally abnormal hemidesmosomes.

Topics: Adolescent; Atrophy; Basement Membrane; Blister; Chronic Disease; Desmosomes; Epidermolysis Bullosa; Female; Humans; Keratins; Skin

Specimens from a patient with epidermolysis bullosa contained many elastic globes in the dermis. Ultrastructurally they were composed of (i) medium electron-dense amorphous substances, (ii) electron-dense round structures, and (iii) fine filaments. These various elements were seldom organized into typical normal elastic fiber and, therefore, it was difficult ultrastructurally to recognize them as such or components thereof. Immunohistochemically, elastic globes were strongly reactive with NKH-1, which stains elastic microfibrils, and antibody to serum amyloid P component (anti-SAP), which binds to elastic fiber microfibrils. However, elastic globes were negative with EKH-4 which recognizes 50 kd keratin of amyloid keratin and cytoid bodies. These findings suggested that elastic globes have a close immunologic profile to elastic fiber microfibrils, but not that of epidermal or epithelial keratin.

Topics: Adult; Antibodies, Monoclonal; Elastic Tissue; Elastin; Epidermolysis Bullosa; Female; Humans; Immunohistochemistry; Keratins; Microscopy, Electron

Topics: Epidermal Cells; Epidermolysis Bullosa; Humans; Keratins; Skin; Skin Transplantation

Blisters have previously been observed in keratinocyte cultures depleted of vitamin A, and in cultures of keratinocytes from patients with epidermolysis bullosa. We have found that blistering may occur in keratinocyte cultures from normal human epidermis, grown under standard conditions, and our aim was to further characterize the mechanism of blister formation. Keratinocytes were seeded at 10(5) cells per 35 mm collagen-coated dish with a 3T3 feeder layer. Blisters were macroscopic, fluid-filled structures which formed irrespective of donor site, or donor age, and were noted on various alternative substrates (collagen, 3T3 + plastic, plastic alone). Blistering commenced around day 12, prior to confluency, and new blisters were formed for up to 5 weeks post-plating. Maximal numbers (up to 70 per dish) were present around days 12 to 20. Cleavage occurred at the cell/collagen interface to form a blister roof composed of 6 to 9 cell layers. The lowest layer appeared metabolically active, but, in contrast to peri-blister regions, lacked hemidesmosomes. The central 2 to 3 layers contained membrane-coating granules and keratohyalin granules while the superficial strata resembled rudimentary corneocytes. Cultures supplemented with 10(-5) M vitamin A formed no blisters, which correlated with suppressed differentiation. Ouabain (10(-7) M) caused blister collapse and a reversible inhibition of new blister formation. We conclude that blisters are a consistent finding in keratinocyte cultures grown under standard conditions. Their formation may be associated with active transport and triggered during differentiation. Further examination of this phenomenon might shed light on whether differentiation itself has an influence on keratinocyte attachment to substrate.

Topics: Adult; Age Factors; Blister; Cell Differentiation; Cells, Cultured; Epidermal Cells; Epidermis; Epidermolysis Bullosa; Humans; Keratins; Lanthanum; Male; Microscopy, Electron; Ouabain; Vitamin A

The epidermolysis bullosa acquisita antigen is a newly discovered major extracellular matrix component within basement membranes beneath stratified squamous epithelia. Human keratinocytes cultured without mesenchymal cells synthesize the major 290 kd chain of the epidermolysis bullosa acquisita antigen.

Topics: Adult; Antigens; Basement Membrane; Cells, Cultured; Culture Media; Electrophoresis, Polyacrylamide Gel; Epidermolysis Bullosa; Humans; Keratins; Molecular Weight; Skin

Why blister formation occurs within the epidermis in epidermolysis bullosa (EB) simplex is not known. One possibility is that there are diminished amounts, absence, or biochemical alterations of one or more structural components of epidermal cell membranes, thereby leading to increased skin fragility. In order to test this hypothesis, biopsy specimens were obtained from clinically normal-appearing skin of patients with simplex, junctional, and dystrophic forms of EB and normal adult volunteers. Immunofluorescence studies were performed on each specimen using eight fluorescein-labeled affinity-purified lectins shown to bind uniformly to epidermal cell membranes of normal human adult skin and neonatal foreskin. To examine the epidermal cytoskeleton, each tissue specimen was also examined using two antikeratin monoclonal antibodies. Irregular and focally granular epidermal membrane staining was noted in each EB simplex specimen examined with the lectin-peanut agglutinin. In contrast, uniformly crisp membrane staining was seen in each specimen from patients with junctional or dystrophic EB and from normal volunteers. This epidermal cell membrane glycosylation defect appears to have the restricted carbohydrate specificity of peanut agglutinin since staining of EB simplex skin with each of the remaining seven lectins was indistinguishable from that seen in skin from patients with the other forms of EB and normal adult skin. Furthermore, the epidermis in EB simplex skin appears to be selectively abnormal since the same tissue specimens demonstrated normal keratin cytoskeleton staining.

Topics: Antibodies, Monoclonal; Antibody Specificity; Cell Membrane; Epidermolysis Bullosa; Glucose; Glycine max; Humans; Keratins; Lectins; Plant Lectins; Skin

Clinical and light and electron microscopic observations of a 16-year-old male patient suffering from ichthyosis hystrix (Curth-Macklin) are presented. The patient had no family history for this disease. The diagnosis was based on the distinct electron microscopic finding of continuous perinuclear tonofibril shells in the keratinocytes. About 10% of the keratinocytes were binucleate and one third contained conspicuous vacuoles. The steroid sulphatase activity in a skin biopsy was normal. Etretinate treatment proved beneficial during the first year of therapy. Later the treatment was less effective. The basic genetic defect persisted in the phenotype of the keratinocytes during etretinate therapy, but the exceedingly thick horny layer was considerably thinned.

Topics: Adolescent; Biopsy; Epidermolysis Bullosa; Etretinate; Humans; Ichthyosis; Keratins; Male; Microscopy, Electron; Skin

Keratinocytes from patients with different types of epidermolysis bullosa (EB) demonstrated an abnormal tendency to blister or bleb formation after 14-22 days in culture. The changes were most marked in samples from cases of junctional EB and were not observed in control cultures of normal skin. These findings suggest the possibility of a primary abnormality of keratinocyte adhesion in different varieties of EB and that keratinocyte culture should provide a useful model for further studies on disorders of adhesion in EB.

Topics: Adolescent; Adult; Blister; Cell Adhesion; Cells, Cultured; Child; Child, Preschool; Epidermis; Epidermolysis Bullosa; Female; Humans; Infant; Keratins; Male; Microscopy, Phase-Contrast; Middle Aged

Electron microscopy is shown to represent an effective tool in the early diagnosis of genetic disorders. On the basis of ultrastructural findings in various dominant and recessive types of ichthyoses and epidermolyses, defects of structural proteins of the skin proved to form the main intrinsic pathogenetic feature of some dominantly inherited types whereas quantitative impairments characterize their closely resembling recessive counterparts. Most of the diseases concerned severely disable the involved patients. Early diagnosis is therefore of high importance. In those cases where an exact diagnosis in newborn children is difficult or impossible with respect to their clinical features, electron microscopy provides the clinician with reliable and significant criteria to differentiate between closely resembling entities.

Topics: Epidermolysis Bullosa; Humans; Hyalin; Ichthyosis; Infant, Newborn; Keratins; Microscopy, Electron; Skin

Topics: Birth Injuries; Blister; Drug Eruptions; Epidermolysis Bullosa; Erythema; Female; Herpes Simplex; Humans; Infant; Infant, Newborn; Infant, Newborn, Diseases; Keratins; Listeria monocytogenes; Lupus Erythematosus, Systemic; Male; Maternal-Fetal Exchange; Miliaria; Nevus; Pregnancy; Pregnancy Complications; Rubella; Skin Diseases; Skin Diseases, Infectious; Stevens-Johnson Syndrome; Sucking Behavior; Syphilis, Congenital; Urticaria Pigmentosa

Topics: Adult; Anemia, Macrocytic; Autoantibodies; Epidermolysis Bullosa; Female; Fluorescent Antibody Technique; Humans; Intrinsic Factor; Keratins; Skin; Thyroiditis