GB3 monoclonal antibody for the diagnosis of junctional epidermolysis bullosa: results of a multicenter study

Diagnosing epidermolysis bullosa type and subtype in infancy using immunofluorescence microscopy: the Stanford experience

The natural history of inherited epidermolysis bullosa (EB) varies significantly across subtypes. When confronted with an infant suspected to have EB, rapidly determining the type and subtype is critical in counselling families accurately about the infant's diagnosis and prognosis. Although transmission electron microscopy (TEM) has been considered the criterion standard for EB diagnosis, immunofluorescence microscopy (IFM) using monoclonal antibodies (mAbs) to EB-specific basement membrane zone proteins has several advantages, but few studies have evaluated the diagnostic utility of IFM. We sought to evaluate the clinical utility of IFM using an expanded panel of EB-specific mAbs. This was a retrospective review of pathology reports from infants younger < 1 year old with suspected EB primarily analyzed with IFM by the Stanford Dermatopathology service. Seventy-seven cases were identified for analysis, of which 20 were suboptimal for IFM analysis. Fifty-five cases were diagnosed with EB and classified as follows: EB simplex (n = 5), junctional EB (n = 31), dystrophic EB (n = 19). TEM was available in 36 of 55 cases (65%). IFM with an expanded panel of EB-specific mAbs should be considered the first-line diagnostic test to evaluate infants with clinically suspected EB.

Herlitz junctional epidermolysis bullosa: diagnostic features, mutational profile, incidence and population carrier frequency in the Netherlands

BACKGROUND

Junctional epidermolysis bullosa, type Herlitz (JEB-H) is a lethal, autosomal recessive blistering disease caused by null mutations in the genes coding for the lamina lucida/densa adhesion protein laminin-332 (LAMB3, LAMA3 and LAMC2).

OBJECTIVES

To present the diagnostic features and molecular analyses of all 22 patients with JEB-H in the Dutch Epidermolysis Bullosa Registry between 1988 and 2011, and to calculate the disease incidence and carrier frequency in the Netherlands.

METHODS

All patients were analysed with immunofluorescence antigen mapping (IF), electron microscopy (EM) and molecular analysis.

RESULTS

The mean lifespan of our patients with JEB-H was 5·8 months (range 0·5-32·6). IF showed absent (91%) or strongly reduced (9%) staining for laminin-332 with monoclonal antibody GB3. In EM the hemidesmosomes and sub-basal dense plates were hypoplastic or absent. We identified mutations in all 22 patients: in 19 we found LAMB3 mutations, in two LAMA3 mutations, and in one LAMC2 mutations. We found three novel splice site mutations in LAMB3: (i) c.29-2A>G resulting in an out-of-frame skip of exon 3 and a premature termination codon (PTC); (ii) c.1289-2_1296del10 leading to an out-of-frame skip of exon 12 and a PTC; and (iii) c.3228+1G>T leading to an exon 21 skip.

CONCLUSIONS

All diagnostic tools should be evaluated to clarify the diagnosis of JEB-H. We have identified 11 different mutations in 22 patients with JEB-H, three of them novel. In the Netherlands the incidence rate of JEB-H is 4·0 per one million live births. The carrier frequency of a JEB-H mutation in the Dutch population is 1 in 249.

Severe osteoporosis treated with teriparatide in a patient affected by recessive epidermolysis bullosa dystrophica

In this work, we describe the clinical and instrumental results of our experience, the first reported in the literature, of the administration of teriparatide to treat severe osteoporosis secondary to epidermolysis bullosa. Already after 2 months of therapy, the patient, a 20-year-old affected by a recessive form of epidermolysis bullosa dystrophica, had less pain and a functional recovery resulting in an improved autonomy; a satisfactory increase in the densitometric values was documented.

Inherited epidermolysis bullosa: past, present, and future

Inherited epidermolysis bullosa encompasses dozens of diseases characterized by mechanical fragility of the skin, blister formation, and abnormal wound healing. Most of the more severe subtypes are associated with clinically significant extracutaneous complications. Some subtypes may lead to death, even in early infancy. Over the past two decades substantial advances have been made to our understanding of the underlying molecular basis for each member of this protean group of diseases. Research has now shifted toward the identification of therapeutic interventions, to include gene therapy, recombinant protein infusions, intradermal injection of allogeneic fibroblasts, and stem cell transplantation, that might eventually lead to a definitive cure for this disease. Other developing therapies being explored are directed toward the enhancement of wound healing and the prevention of potentially life-threatening skin cancers in these patients.

Inherited epidermolysis bullosa

Inherited epidermolysis bullosa (EB) encompasses a number of disorders characterized by recurrent blister formation as the result of structural fragility within the skin and selected other tissues. All types and subtypes of EB are rare; the overall incidence and prevalence of the disease within the United States is approximately 19 per one million live births and 8 per one million population, respectively. Clinical manifestations range widely, from localized blistering of the hands and feet to generalized blistering of the skin and oral cavity, and injury to many internal organs. Each EB subtype is known to arise from mutations within the genes encoding for several different proteins, each of which is intimately involved in the maintenance of keratinocyte structural stability or adhesion of the keratinocyte to the underlying dermis. EB is best diagnosed and subclassified by the collective findings obtained via detailed personal and family history, in concert with the results of immunofluorescence antigenic mapping, transmission electron microscopy, and in some cases, by DNA analysis. Optimal patient management requires a multidisciplinary approach, and revolves around the protection of susceptible tissues against trauma, use of sophisticated wound care dressings, aggressive nutritional support, and early medical or surgical interventions to correct whenever possible the extracutaneous complications. Prognosis varies considerably and is based on both EB subtype and the overall health of the patient.

Blistering skin diseases: a bridge between dermatopathology and molecular biology

Although dermatopathology and molecular biology are often considered to be separate laboratory disciplines, the respective approaches are far from mutually exclusive. This is certainly the case for understanding the pathology of blistering skin diseases, both acquired and inherited. For example, in toxic epidermal necrolysis, dermatopathology in isolation may provide few clues to disease pathogenesis. There is widespread keratinocyte apoptosis and a variable infiltrate of cytotoxic T cells, but morphology alone offers little insight into what causes the epidermal destruction. In contrast, molecular biology studies have revealed several key processes that help explain the keratinocyte death, including increased expression of death receptors and their ligands on keratinocyte cell membranes as well as the presence of local or systemic immunocyte-derived cytolytic granules. For some inherited blistering diseases, however, such as epidermolysis bullosa, the molecular pathology is complex and difficult to unravel in isolation, yet the addition of dermatopathology is helpful in focusing molecular investigations. Notably, immunolabelling of cell adhesion proteins using specific antibody probes can identify reduced or absent immunoreactivity for candidate genes/proteins. Bridging dermatopathology and molecular biology investigations facilitates a greater understanding of disease processes, improves diagnostic accuracy, and provides a basis for the development and appraisal of new treatments.

Treatment decision-making for patients with the Herlitz subtype of junctional epidermolysis bullosa

The Herlitz subtype of junctional epidermolysis bullosa (JEB-H) is a lethal genetic disorder characterized by recurrent and persistent erosions of the epithelial surfaces that heal with exuberant granulation tissue. In addition, respiratory distress, refractory anemia and failure to thrive are often seen. Mortality in the first year of life approaches 90%. JEB-H is caused by mutations in the genes that encode the protein laminin 5, a structural molecule involved in the adhesion of epidermis to dermis. There is currently no cure for JEB-H. Medical interventions treat complications but do not ultimately limit mortality. Ethical principles contend that offering comfort and company to the patient and family, not aggressive therapies, should comprise the mainstay of care for affected infants.

A comparative study between transmission electron microscopy and immunofluorescence mapping in the diagnosis of epidermolysis bullosa

The classification of epidermolysis bullosa (EB) into 3 main subtypes has been based on transmission electron microscopy (TEM) that is able to directly visualize and quantify specific ultrastructural features. Immunofluorescence antigenic mapping (IFM) is a technique that determines the precise level of skin cleavage by determining binding sites for a series of antibodies. To date, no study has compared the accuracy of these two techniques in diagnosing the major types of EB. A prospective cohort of 33 patients thought to have EB on clinical grounds had TEM, IFM, and genetic testing performed. The sensitivities and specificities of TEM and IFM were calculated compared with the genetic results. Of 33 cases, 30 had a positive EB diagnosis. TEM subclassified EB into its three major forms in 24/30 cases (80%) and IFM in 29/30 cases (97%). Overall, TEM sensitivities and specificities when compared with genetic results were 71% and 81%, respectively. IFM sensitivities and specificities when compared with genetic results were 97% and 100%, respectively. If a patient tested positive for EB by IFM, the likelihood ratio of having a particular type of EB was consistently greater than 20 against the reference standard (compared with a likelihood ratio less than 10 for TEM). Our results indicate that the diagnosis of EB is improved (sometimes substantially) by the use of IFM compared with TEM.

Bone mineralization in children with epidermolysis bullosa

BACKGROUND

Various factors may have deleterious effects on bone health in patients with epidermolysis bullosa (EB).

OBJECTIVES

In a retrospective notes review, to assess bone mineralization in children with EB and to identify the relative contributions of nutrition, activity and disease severity to low bone mass.

METHODS

Thirty-nine children with EB [32 recessive dystrophic EB (RDEB), four Dowling-Meara EB simplex (DMEBS) and three junctional EB (JEB)] had lumbar spine bone mass measured using dual X-ray absorptiometry (GE Lunar Prodigy; GE Healthcare, Chalfont St Giles, U.K.). Seventy-six healthy children were also studied. Weight and height were recorded and mobility was rated.

RESULTS

Children with RDEB and JEB, but not those with DMEBS, had lower bone mineral density SD scores than controls; differences remained after adjusting for the smaller body size of the patients. Bone mass was best predicted by mobility rating.

CONCLUSIONS

Children with RDEB and JEB have low bone mass after adjusting for their smaller size, which may put them at risk for fragility fractures. Low bone mass was best predicted by the level of mobility, raising the hypothesis that improving activity or bone loading may be a potential preventive intervention in these children. However, as low bone mass may be multifactorial in these children, more detailed investigation of potential aetiological factors is required before interventions are planned.

Prenatal diagnosis for severe inherited skin disorders: 25 years' experience

BACKGROUND

Over the last 25 years there have been major advances in methods for prenatal testing of inherited skin disorders. Since 1979, our group at the St John's Institute of Dermatology has performed 269 prenatal diagnoses, using a variety of approaches, including fetal skin biopsy (FSB), chorionic villus sampling (CVS) and preimplantation genetic diagnosis (PGD).

OBJECTIVES

This study was designed to review the clinical indications, testing procedures and laboratory analyses for all prenatal tests conducted at St John's over this period.

METHODS

FSBs were examined for morphological and, when relevant or feasible, immunohistochemical abnormalities. The DNA-based tests involved screening by nucleotide sequencing, restriction enzyme digests or, in a few cases, by linkage analysis. Results Of the 269 tests, 191 were FSB, 76 were CVS and two were PGD. The major indications for FSB were epidermolysis bullosa (EB) (138 cases, including 88 junctional and 48 dystrophic), ichthyoses (37 cases, including 22 tests for harlequin ichthyosis) and oculocutaneous albinism (12 cases). Of the CVS procedures, 75 were for EB (40 junctional, 35 dystrophic) and one was for the EEC (ectrodactyly, ectodermal dysplasia, clefting) syndrome. Both of the PGD procedures were for the skin fragility-ectodermal dysplasia syndrome. All tests provided accurate diagnoses and the fetal loss rate was approximately 1% for both FSB and CVS.

CONCLUSIONS

The development of prenatal testing has proved to be of great benefit for individuals or couples at risk of having children with severe inherited skin disorders and, in the absence of a cure, prenatal testing along with appropriate counselling has become an important translational benefit of basic research and an integral part of clinical management.

Progress in epidermolysis bullosa: from eponyms to molecular genetic classification

Epidermolysis bullosa, a clinically and genetically diverse group of heritable mechanobullous disorders characterized by skin fragility in the cutaneous basement membrane zone, has become a prototype for the recent progress in molecular genetics of genodermatoses. The different forms of epidermolysis bullosa have been linked to mutations in no less than 10 distinct genes encoding the major structural basement membrane zone proteins. This information has formed a basis for refined molecular classification with prognostic implications, improved genetic counseling, and prenatal and preimplantation genetic diagnosis.

Progress in epidermolysis bullosa: Genetic classification and clinical implications

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.

Junctional epidermolysis bullosa in the Middle East: clinical and genetic studies in a series of consanguineous families

BACKGROUND

Junctional epidermolysis bullosa (JEB) is a group of inherited blistering diseases characterized by epidermal-dermal separation resulting from mutations that affect the function of critical components of the basement membrane zone. This group of autosomal recessive diseases is especially prevalent in regions where consanguinity is common, such as the Middle East. However, the clinical and genetic epidemiology of JEB in this region remains largely unexplored.

OBJECTIVE

The aim of the present study was to assess a series of consanguineous JEB families originating from the Middle East.

METHODS

We identified 7 families referred to us between 1998 and 1999 and originating from the United Arab Emirates, Saudi Arabia, Sudan, Yemen, and Israel. Histologic, immunofluorescence, and electron microscopy studies were performed to direct the subsequent molecular analysis. DNA obtained from all family members was amplified by means of polymerase chain reaction and analyzed by conformation-sensitive gel electrophoresis with subsequent direct sequencing.

RESULTS

In 6 families presenting with the clinical and histologic features distinctive for JEB, mutations in genes encoding 1 of the 3 subunit polypeptides of laminin-5 were identified. Two families each had mutations in LAMB3, 2 in LAMA3, and 2 in LAMC2. Out of 7 distinct mutations, 5 were novel and 2 were recurrent. No relationship was found between the presence of nonsense/frameshift mutations in laminin-5 genes and perinatal mortality, contradicting a major genotype-phenotype correlation previously reported in the European and US literature. Similarly, none of the recurrent LAMB3 hot spot mutations previously described in other populations was found in our series. Finally, in a family with the clinical diagnosis of generalized atrophic benign epidermolysis bullosa, a homozygous non-sense mutation in Col17A1 gene (encoding the BPAG2 antigen) was identified.

CONCLUSION

The present report suggests (1) the existence of a unique spectrum of mutations in the Middle East populations and (2) the need for the implementation of a diagnostic strategy tailored to the genetic features of JEB in this region.

Herlitz junctional epidermolysis bullosa presenting at birth with anonychia: a case report and review of H-JEB

A 15-day-old Yemeni boy presented with anonychia and granulomatous nail beds and white patches in the mouth. Biopsy specimens from the nail beds were nondiagnostic. Shortly thereafter the child developed multiple tense bullae, a hoarse voice, and poor appetite. Hematoxylin and eosin staining along with monoclonal antibody studies of a skin biopsy specimen revealed subepidermal bullae through the lamina lucida and a marked decrease in laminin 5. A diagnosis of junctional epidermolysis bullosa Herlitz variant was made. His course was complicated by multiple nonhealing wounds, oral pharyngeal involvement, sepsis, anemia, and poor nutrition, leading to his eventual death. This report emphasizes the unusual presentation of Herlitz junctional epidermolysis bullosa with anonychia as the initial finding and a relatively prolonged period before cutaneous blister formation, resulting in delay of diagnosis.

Adhesion receptors in health and disease

Cell adhesion molecules have been recognized to play a major role in a variety of physiological and pathological phenomena. They determine the specificity of cell-cell binding and the interactions between cells and extracellular matrix proteins. Some of them may also function as receptors that trigger intracellular pathways and participate in cellular processes like migration, proliferation, differentiation, and cell death. The receptors that mediate adhesion between epithelial cells that are discussed in this review include integrins, selectins, the immunoglobulin superfamily members, and cadherins. The intent of this review is to inform the reader about recent advances in cellular and molecular functions of certain receptors, specifically those that are considered important in cell adhesion. We have deliberately not provided all-inclusive detailed information on every molecule, but instead, have presented a generalized overview in order to give the reader a global perspective. This information will be useful in enhancing the reader's understanding of the molecular pathology of diseases and recognizing the potential role of these receptors and ligands as therapeutic agents.

Immunohistopathologic diagnosis of epidermolysis bullosa

Routine histologic study usually is insufficient to subclassify epidermolysis bullosa (EB); currently, electron microscopic evaluation has been the gold standard. A major advance recently has been made in elucidating the molecular basis of several major forms of EB. Concomitantly, immunoreagents have been developed to map antigens in the basement membrane zone. Some of these reagents facilitate the classification of EB into types and subtypes and can be used as an adjunct informative screening procedure to direct mutation identification efforts using DNA technologies. The current review provides an overview of these recent developments and a more detailed account of the immunohistopathologic diagnosis of EB.

Molecular pathology of the cutaneous basement membrane zone

Recent research has provided considerable information concerning the biology of the cutaneous basement membrane zone (BMZ) in health and disease. In particular, identification of pathogenetic mutations in the genes encoding protein components at the BMZ has done much to increase our understanding of the inherited skin blistering disease, epidermolysis bullosa (EB). As the molecular pathology of different forms of EB is elucidated, correlations between genotype and phenotype become apparent. Determination of specific mutations in patients and families has not only clinical significance, but has also led to the introduction of DNA-based prenatal testing for severe forms of disease, and has laid the foundations for the development of future treatments including gene therapy.

Extent of laminin-5 assembly and secretion effect junctional epidermolysis bullosa phenotype

Junctional epidermolysis bullosa (JEB) is an autosomal recessive skin blistering disease with both lethal and nonlethal forms, with most patients shown to have defects in laminin-5. We analyzed the location of mutations, gene expression levels, and protein chain assembly of the laminin-5 heterotrimer in six JEB patients to determine how the type of genetic lesion influences the pathophysiology of JEB. Mutations within laminin-5 genes were diversely located, with the most severe forms of JEB correlating best with premature termination codons, rather than mapping to any particular protein domain. In all six JEB patients, the laminin-5 assembly intermediates we observed were as predicted by our previous work indicating that the alpha3beta3gamma2 heterotrimer assembles intracellularly via a beta3gamma2 heterodimer intermediate. Since assembly precedes secretion, mutations that disrupt protein-protein interactions needed for assembly are predicted to limit the secretion of laminin-5, and likely to interfere with function. However, our data indicate that typically the most severe mutations diminish mRNA stability, and serve as functional null alleles that block chain assembly by resulting in either a deficiency (in the nonlethal mitis variety) or a complete absence (in lethal Herlitz-JEB) of one of the chains needed for laminin-5 heterotrimer assembly.

Gastric outlet obstruction and epidermolysis bullosa

We describe a case of pyloric atresia coexisting with epidermolysis bullosa, almost certainly of the junctional type. The coexistence of pyloric atresia and junctional epidermolysis bullosa (PA-JEB syndrome) has been repeatedly observed. This syndrome has several clinical features that distinguish it from Herlitz junctional epidermolysis bullosa (JEB). These include a lack of prominent granulation tissue formation and increased frequencies of genitourinary tract involvement and ear anomalies. Aplasia cutis congenita is sometimes present; esophageal atresia is uncommonly present. In all 12 patients examined to date, normal basement membrane zone expression of laminin-5 biochemically distinguishes PA-JEB syndrome from Herlitz JEB. Mutations in the beta 4 integrin gene have been observed in one patient with PA-JEB syndrome. Thus there are both clinical and biochemical reasons to separate the PA-JEB syndrome from Herlitz JEB. This is the second known case of papillary hyperplasia of the amnion to be seen in any setting. The other was a case of JEB without pyloric atresia.

The role of immunohistochemistry in the diagnosis of the non-lethal forms of junctional epidermolysis bullosa

Skin biopsies from four patients with similar clinical phenotypes of non-lethal junctional epidermolysis bullosa (JEB) were investigated by electron microscopy and immunohistochemistry. Electron microscopy revealed cleavage within the lamina lucida in each case, but in addition, there was considerable variability in the number and ultrastructure of hemidesmosome-anchoring filament complexes. Immunohistochemical staining of the dermal-epidermal junction, using monoclonal antibodies to laminin 5 and the 180-kDa bullous pemphigoid antigen, showed reduced laminin 5 staining with normal 180-kDa bullous pemphigoid antigen labelling in two cases, and reduced or absent 180-kDa bullous pemphigoid antigen staining with normal laminin 5 labelling in the other two cases. Whereas electron microscopy is invaluable for the diagnosis of JEB as a group of diseases, immunohistochemistry is able to provide insight into the molecular pathology of non-lethal JEB and reveal abnormalities in candidate genes and proteins underlying this group of genetic blistering disorders.

Altered expression of epithelial integrins and extracellular matrix receptors in oral erythema multiforme

Inflammation and ulceration at the epithelium-connective tissue interface, a characteristic of erythema multiforme (EM), may be associated with altered molecular attachment of basal keratinocytes. To determine the expression of basal keratinocyte-associated integrins and their basement membrane ligands in oral EM, specimens of clinically and microscopically confirmed EM (n = 12) and mucosal controls (n = 7) were stained immunohistochemically for the integrins alpha 3, beta 6, beta 1, and beta 4 and for extracellular matrix proteins laminin 1, laminin 5, collagen IV, and collagen VII using a standard avidin-biotin-peroxidase technique. In EM, results showed increased staining intensity for all integrins studied in basal and suprabasal keratinocytes. Basement membrane-associated staining of a6 and b4 was intense, but disrupted and fragmented. In EM, integrin staining was most marked at the summit of the connective tissue papillae. Laminin 5 staining was more intense than in controls, was frequently fragmented, and extended into the lamina propria. Laminin 1 staining was discontinuous and was frequently less intense than in controls. Collagen IV staining in EM was interrupted along the basement membrane. Collagen VII staining was fragmented but unchanged in intensity. These alterations in interface adhesion molecules suggest that hemidesmosome-associated molecules are important in the pathogenesis of EM. The staining intensities and patterns of expression of these adhesion molecules suggest that oral EM is initially focused in the connective tissue papillae.

Defective integrin alpha 6 beta 4 expression in the skin of patients with junctional epidermolysis bullosa and pyloric atresia

Junctional epidermolysis bullosa (JEB) is a heterogeneous group of rare inherited skin disorders in which defects in cell adhesion components cause incomplete formation of hemidesmosomes. We have immunohistochemically examined the skin from ten JEB patients (JEB gravis, n = 4; JEB mitis, n = 3; JEB plus pyloric atresia [JEB/PA], n = 3) using monoclonal antibodies specific for the integrin adhesion receptors alpha 3 beta 1 and alpha 6 beta 4, and for the alpha 3, beta 3, and gamma 2 subunits of the basement membrane ligand, laminin 5. Consistent with our previous reports, only the JEB gravis patients without associated pyloric atresia expressed reduced or absent epitopes for laminin-5 subunits in their epidermal basement membrane. In contrast, all three JEB/PA cases showed abnormalities in integrin alpha 6 beta 4, but not in laminin 5, expression in their basal epidermal cells. Integrin beta 4 subunit was undetectable in the biopsied epidermis of these JEB/PA individuals using five different monoclonal antibodies that recognize both intra- and extracellular epitopes. The absence of the beta 4 subunit in the epidermis of JEB/PA specimens was confirmed by Western blot analysis of tissue extracts. Epidermal expression of the integrin alpha 6 subunit was variable in the JEB/PA patients. Abnormal integrin alpha 6 beta 4 expression may define the subset of JEB cases with pyloric atresia. These results strongly implicate a functional role for alpha 6 beta 4 in the formation of complete hemidesmosomes and in stable adhesion of basal keratinocytes to the basement membrane in vivo.

Beta4 integrin is required for hemidesmosome formation, cell adhesion and cell survival

The integrin heterodimer alpha 6 beta 4 is expressed in many epithelia and in Schwann cells. In stratified epithelia, alpha 6 beta 4 couple with BPAG1-e and BPAG2 to form hemidesmosomes, attaching externally to laminin and internally to the keratin cytoskeleton. To explore the function of this atypical integrin, and its relation to conventional actin-associated integrins, we targeted the removal of the beta 4 gene in mice. Tissues that express alpha 6 beta 4 are grossly affected. Stratified tissues are devoid of hemidesmosomes, display only a very fragile attachment to the basal lamina, and exhibit signs of degeneration and tissue disorganization. Simple epithelia which express alpha 6 beta 4 are also defective in adherence, even though they do not form hemidesmosomes. In the absence of beta 4, alpha 6 is dramatically downregulated, and other integrins do not appear to compensate for the loss of this heterodimer. These data have important implications for understanding integrin function in cell-substratum adhesion, cell survival and differentiation, and for understanding the role of alpha 6 beta 4 in junctional epidermolysis bullosa, an often lethal human disorder with pathology similar to our mice.

Compound heterozygosity for nonsense ans missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa

Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of a nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.

A homozygous deletion mutation in the gene encoding the 180-kDa bullous pemphigoid antigen (BPAG2) in a family with generalized atrophic benign epidermolysis bullosa

The 180-kDa bullous pemphigoid antigen (BPAG2) is a candidate gene/protein for mutations in some forms of junctional epidermolysis bullosa. In this study, we searched for mutations in BPAG2 in a large Austrian pedigree with generalized atrophic benign epidermolysis bullosa, a distinct nonlethal form of junctional epidermolysis bullosa, using polymerase chain reaction amplification of genomic DNA, heteroduplex analysis of the polymerase chain reaction products, and direct nucleotide sequencing. We identified a homozygous 2-bp deletion within the coding region of BPAG2 in the affected individuals. This mutation results in a frameshift and downstream stop codons on both alleles, predicting an absence of functional protein. These findings illustrate the molecular basis of the skin fragility in this family and attest to the importance of the 180-kDa bullous pemphigoid antigen in the attachment of the epidermis to the underlying dermoepidermal basement membrane.

Compound heterozygosity for nonsense and missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa

Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DNA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.

Hemidesmosome ontogeny in digit skin of the human fetus

Hemidesmosomes are junctional complexes involved in the attachment of epidermal basal keratinocytes to the basement membrane. To try to understand better the sequence of events in the morphogenesis of hemidesmosomes, we undertook an ultrastructural analysis of hemidesmosome formation in fetal and neonatal digit skin. Hemidesmosomes, defined as membrane-associated densities or plaques, were counted and scored for three morphological characteristics: (1) the presence of a sub-basal dense plate, (2) association with anchoring filaments within the lamina lucida and (3) contacts with intermediate filaments. No hemidesmosomes were evident at 7 weeks' gestational age. Between 9 and 15 weeks the number of hemidesmosomes increased by about fourfold (from 20.6 +/- 3.8 (SD) to 95.5 +/- 8.4 per 40 micro m of basal cell plasma membrane; P < 0.01). The association of hemidesmosomes with intermediate filaments and anchoring filaments also increased after 15 weeks (P < 0.05). Early attachment plaques first appeared as triangular focal densities on the basal plasma membrane with the appearance of sub-basal dense plates, which later became both larger and more electron dense. By 15 weeks, an inner plaque could be distinguished from the outer plaque, which coincided with a closer association with intermediate filaments. Hemidesmosomes appeared fully developed by 15 weeks' gestation. This study illustrates the structural relationship of hemidesmosomes to both intra- and extracellular filaments, suggesting close functional interactions. The complexity of the hemidesmosome plaque is also revealed early during development.

Gamma 2 chain of laminin-5 is recognized by monoclonal antibody GB3

Herlitz junctional epidermolysis bullosa is an autosomal recessive disorder characterized by generalized blistering at the lamina lucida of the cutaneous basement membrane. The monoclonal antibody GB3 has been used as a diagnostic probe because of its lack of reactivity in patient skin. The antigen recognized by GB3 has been identified as laminin-5, a glycoprotein consisting of three subunits (alpha 3, beta 3 and gamma 2). To identify the laminin-5 protein chain that contains the epitope recognized by GB3 and to determine if chain assembly is required for antibody recognition, we expressed a gamma 2 protein constructed from a full-length gamma 2 cDNA. Radioimmunoprecipitation of the culture medium from 293 cells revealed that both GB3 and anti-gamma 2 polyclonal antibodies were capable of directly precipitating recombinant gamma 2 without coprecipitation of other proteins. In immunodepletion experiments, each antibody removed most of the protein that was reactive with the other antibody. The epitope recognized by GB3 is present only when the complex is in the native conformation because GB3 reacted only with the non-reduced laminin-5, but not the reduced laminin-5 in immunoblots. Moreover, because GB3 reacted with laminin-5 of SCC25 cells (gamma 2 in the heterotrimer) but not recombinant gamma 2 in 293 cells (gamma 2 alone) during indirect immunofluorescence staining, this epitope may be dependent upon a less stable conformation of gamma 2. We conclude that GB3 recognizes the gamma 2 chain of laminin-5 and that the epitope is entirely contained in the native form of the gamma 2 chain.

Junctional epidermolysis bullosa and pyloric atresia: a distinct entity. Clinical and pathological studies in five patients

Junctional epidermolysis bullosa (JEB) associated with pyloric atresia (PA) is a distinct entity which is inherited as an autosomal recessive disorder. We describe five patients with this association; four died in the neonatal period and one is still alive at 4 years of age. The cutaneous lesions in these patients are identical or similar to those in other JEB subtypes. Urinary tract involvement is part of the syndrome and presents a problem for long-term survival. Using the monoclonal antibody GB3 we investigated skin biopsies from three of our patients and showed normal expression in all of them, unrelated to the outcome of their disease. This indicates that the GB3 monoclonal antibody is without prognostic significance in this syndrome. It is clear that JEB with PA is a distinct entity. The molecular basis as yet is unknown.

Ultrastructural clues to genetic disorders of skin: the dermal-epidermal junction

The candidate gene approach in tracking the underlying cause of a number of genetic skin disorders has proved remarkably effective over the past few years. Electron microscopy has had a unique role in identifying morphologic abnormalities of various fibers, fibrils, and filaments, and helping to localize biochemical constituents to these structures. Nowhere is this approach more strongly demonstrated than in its application to different forms of epidermolysis bullosa, of which two major forms, junctional and dystrophic epidermolysis bullosa, are caused by mutations of genes encoding structural proteins in the dermal-epidermal junction.

Integrins and basement membrane proteins in skin carcinomas

The topography of some integrins and basement membrane proteins in cutaneous basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) has been studied by immunohistochemistry. The typical cell-to-cell distribution of alpha 2 beta 1 and alpha 3 beta 1 of normal epidermis becomes pericellular in both BCC and SCC cells. BCC and SCC also showed different patterns of expression of alpha 6 beta 4, the integrin normally located at the basal surface of basal epidermal keratinocytes. SCC showed high expression and pericellular distribution of alpha 6 beta 4, while BCC did not express alpha 6 beta 4 at all also in Western blotting. The basement membrane was markedly different in the two tumor types. Laminin and collagen type IV were conserved in the basement membrane zone of both tumors while nicein/kalinin was absent from BCC cells. The simultaneous loss of expression of alpha 6 beta 4 and nicein/kalinin in BCC cells but not in SCC cells indicates that alpha 6 beta 4 and one potential ligand may be co-regulated in both BCC and SCC. We suggest a role for this phenomenon in the pathogenesis of these epidermal tumors.

Prenatal exclusion of pyloric atresia-junctional epidermolysis bullosa syndrome

BACKGROUND

The pyloric atresia--junctional epidermolysis bullosa (PA-JEB) syndrome is an autosomal recessive disorder with a poor prognosis. Electron microscopy of fetal skin has been the only reliable method for prenatal diagnosis.

OBJECTIVE

The purpose of this study was to make the prenatal diagnosis of PA-JEB syndrome with a more reliable method by means of immunocytochemical probes.

METHODS

Expression of a range of basement membrane antigens was examined in different types of JEB. On the basis of the results, a fetal skin biopsy specimen was obtained for prenatal diagnosis.

RESULTS

In PA-JEB syndrome (n = 2), GB3 antigen (BM600) was normally expressed; the 19-DEJ-1 antigen was completely absent. In fetal skin at risk for PA-JEB syndrome, the 19-DEJ-1 antigen was normally expressed, and no ultrastructural abnormality was found by electron microscopy. A normal male infant was delivered at 38 weeks of pregnancy.

CONCLUSION

19-DEJ-1 monoclonal antibody serves as a useful probe for the prenatal diagnosis of PA-JEB syndrome.

The National Epidermolysis Bullosa Registry

Since its inception in 1986, the NEBR has proved to be an excellent example of how a relatively small allocation of federal research funds for the development of a registry of cases of a single rare disease can have a major impact on the rapid expansion in the depth of knowledge of not only the disease itself but of a number of associated biologic principles, including keratinization and epithelial cell-extracellular matrix interactions. At present, the NEBR is generating extensive clinical, laboratory, and demographic data, both from cross-sectional and longitudinal perspectives, as well as establishing a centralized cell and tissue bank that will serve the scientific community at large as a valuable resource for future basic research on this oftentimes devastating genetic disease.

Immunofluorescent analysis of the basement membrane zone in lichen planus suggests destruction of the lamina lucida in bullous lesions

Lichen planus is an inflammatory dermatosis which is characterized histologically by an intense lymphocytic infiltrate at the dermal epidermal junction. This frequently results in disruption of the basement membrane zone, occasionally causing clinical blisters. In order to better understand the specific portion of the basement membrane zone which is disrupted by the lymphocytic infiltrate, we examined 7 cases of lichen planus with antibodies directed against anchoring filaments (GB3), the bullous pemphigoid antigen, anchoring fibrils (type VII collagen) and type IV collagen. In lesions without separation at the BMZ, all antibodies were strongly expressed, as in normal skin. In lesions with early separation, there was a focal decrease in GB3 staining, but types VII and IV collagen labelled normally. In lesions resulting in blisters, GB3 staining was essentially absent, and anti-types IV and VII collagen remained, but stained in a disrupted, less discrete pattern. The bullous pemphigoid antigen showed only slight deviation from the normal staining pattern. These findings suggest that the basement membrane zone in lichen planus is disrupted in the lamina lucida region. The lamina densa and sub-lamina densa zones remain intact even in bullous lesions of lichen planus.

Herlitz junctional epidermolysis bullosa keratinocytes display heterogeneous defects of nicein/kalinin gene expression

Previous studies have correlated the Herlitz junctional epidermolysis bullosa (H-JEB) to an altered expression of the basement membrane component nicein/kalinin. This heterotrimeric glycoprotein appears to be present in H-JEB tissues in an abnormal form, because a number of antibodies specific to the protein either do not react with or weakly stain the epidermal basement membranes of most of the patients. With cDNA probes encoding each subunit of nicein and polyclonal antibodies raised against bacterial fusion polypeptides corresponding to the individual chains of the protein, we have molecularly analyzed the expression of nicein in H-JEB tissues and cultured keratinocytes. By immunohistochemistry, Northern blot, and protein analysis, we show a defective synthesis of one of the nicein subunits in six cases of H-JEB from five different consanguineous families. In two patients, the disease correlates with an impaired synthesis of the nicein B2 (nic B2) chain, in three others with that of the B1 (nic B1) chain, and in a sixth patient with that of the heavy A (nic A) chain. In this report, we thus demonstrate that H-JEB is a genetically heterogeneous disease and we provide strong evidence that the genes of nicein are the candidates for this genodermatosis.

Nicein (BM-600) in junctional epidermolysis bullosa: polyclonal antibodies provide new clues for pathogenic role

We have raised polyclonal antibodies against each of three subunits of the new basement membrane component nicein (formerly BM-600), the antigen recognized by the monoclonal antibody GB3 (Biochem Biophys Acta 942:45-56, 1988). Preparation of such antibodies was achieved from gel electrophoresis purification of nicein isolated by immuno-affinity chromatography. These antibodies were reactive with each transblotted denatured nicein subunit and recognized the native protein both in cultured keratinocytes and in all normal human basement membranes where the GB3 antigen is located. A reciprocal immuno-cross-reactivity was detected with the antibodies directed against the 100-kD and 150-kD (sometimes resolved as a 146-150-kD doublet) subunits of nicein, showing that they share some identical epitopes. In tissues and keratinocyte cultures from patients with the Herlitz form of junctional epidermolysis bullosa (H-JEB), GB3 is unable to recognize nicein, and the question arises whether this is due to an absence of synthesis or a structural abnormality of the protein. We report here that the polyclonal antibody directed against the 150-kD subunit of nicein binds its antigen in H-JEB patients (although usually less intensely than in control skin), whereas the other two antibodies either do not recognize or recognize only weakly their respective antigen subunits. These data suggest that nicein is present but structurally altered in basement membranes from H-JEB tissues. Furthermore, in non-Herlitz junctional and dystrophic types of epidermolysis bullosa, all three polyclonal antibodies recognize their antigens normally. Consequently, such antibodies should serve as potentially useful molecular tools for studying the expression of nicein in H-JEB.

Cultured keratinocyte allografts and wound healing in severe recessive dystrophic epidermolysis bullosa

BACKGROUND

Patients with recessive dystrophic epidermolysis bullosa (RDEB) frequently have painful erosions that are slow to heal. There is no definitive treatment; therefore any therapy that improves wound healing would be beneficial to these patients.

OBJECTIVE

Our purpose was to assess the effects of cultured allogeneic keratinocytes on wound healing in RDEB.

METHODS

Ten patients with RDEB and dermatome-induced superficial dermal wounds were studied. Cultured keratinocyte grafts were applied to part of the wound, with another part left ungrafted. Both sites were assessed clinically and microscopically, particularly with regard to basement membrane zone reconstitution.

RESULTS

Apart from minor differences in keratinocyte differentiation and a moderate analgesic effect induced by the graft, there were no other distinguishing findings in wound healing in the grafted and nongrafted sites.

CONCLUSION

There was little clinical benefit from cultured keratinocyte allografts in wound healing in RDEB. However, this study showed that RDEB keratinocytes have an inherent capacity to express some type VII collagen epitopes transiently during wound healing, although this was not associated with the detection of anchoring fibrils.

Expression and topography of integrins and basement membrane proteins in epidermal carcinomas: basal but not squamous cell carcinomas display loss of alpha 6 beta 4 and BM-600/nicein

The expression and topography of some integrins and basement membrane proteins in cutaneous basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) have been studied by immunohistochemistry and Western blotting. It has been shown that the typical cell-to-cell distribution of alpha 2 beta 1 and alpha 3 beta 1 found in normal epidermis is replaced by pericellular distribution in both BCC and SCC cells. BCC and SCC also showed different patterns of expression of alpha 6 beta 4, an integrin heterodimer normally lining the basal surface of basal epidermal keratinocytes: whereas SCC showed high expression and pericellular distribution of alpha 6 beta 4, BCC cells did not express this integrin at all. The absence of alpha 6 and beta 4 subunits from BCC extracts was confirmed by Western blotting. The molecular composition of the basement membrane was markedly different in the two types of epidermal tumors. Whereas laminin and collagen type IV were conserved in the basement membrane zone of both tumors, the molecular complex BM-600/nicein, which is recognized by the monoclonal antibody GB3 and is possibly identical to the previously described basement membrane glycoproteins kalinin and epiligrin, was absent from BCC cells. Then, the simultaneous loss of expression of alpha 6 beta 4 and BM-600/nicein in BCC cells but not in SCC cells indicates that alpha 6 beta 4 integrin and one of its potential ligands may be co-regulated in both BCC and SCC, thus suggesting a role for this phenomenon in the pathogenesis and clinical behavior of these epidermal tumors.

Expression of integrin alpha 6 beta 4 in junctional epidermolysis bullosa

The integrin alpha 6 beta 4 is a member of the integrin family of adhesion receptors. The integrin alpha 6 beta 4 is preferentially expressed in stratified squamous epithelia, where it is localized in hemidesmosomes. A reduced number of rudimentary hemidesmosomes is often found in skin from patients with junctional epidermolysis bullosa (JEB). In this study we have investigated the expression of alpha 6 beta 4 in skin specimens of patients with junctional (one non-lethal, two lethal) and dystrophic (two) epidermolysis bullosa, using immunofluorescent (IF) staining with five different monoclonal antibodies against the alpha 6 and beta 4 subunits. The intensity of IF staining of the integrin alpha 6 beta 4 and bullous pemphigoid antigen (BPA) was unreduced along the epidermal basement membrane zone (EBMZ) of all EB patients, compared to that in skin of healthy human controls. However, in the skin of two patients with lethal (Herlitz) JEB, who did not express GB3, IF staining of integrin alpha 6 beta 4 and BPA showed a "stitchy" discontinuous linear pattern along the EBMZ with interruptions at the borders of adjoining basal keratinocytes. The same results were obtained by immunoelectron microscopy. They corresponded with freeze-induced partial cell detachment from the basement membrane at the ultimate baso-lateral edge of the basal keratinocytes in lethal JEB skin. The basal lamellipodia at that location almost completely lacked tonofilaments and hemidesmosomes. Furthermore, in JEB there was a split between the intra- and extracellular epitopes of the integrin alpha 6 beta 4 receptor, whereas the integrin remains intact in salt-split skin. This suggests that the defect is in alpha 6 beta 4 itself or perhaps its ligand.

Diagnosis and prenatal diagnosis of epidermolysis bullosa herpetiformis (Dowling-Meara) in a mother, two affected children, and an affected fetus

In utero skin biopsy was performed on a fetus at risk of an uncertain form of epidermolysis bullosa (EB). The mother had produced two affected offspring diagnosed variously as having junctional or dystrophic EB. The two offspring and the fetus were products of different fathers. The mother claimed to have no disease and on clinical examination was without blisters. Examination of the fetal skin biopsy by light and electron microscopy revealed separation of the epidermal sheet from the majority of the biopsy sample, although occasional remnants of basal cells remained associated with the basement membrane. Aggregations of keratin filaments were observed within basal cells of the detached epidermis and in the attached basal cell remnants. The diagnosis was thus suggested to be epidermolysis bullosa Dowling-Meara. Re-review of the clinical and laboratory data from the affected infants revealed a clinical and histological pattern consistent with this diagnosis. Further discussion with the mother revealed that her skin had blistered as a child and that she presently had hyperkeratotic palms and soles. This history is consistent with the autosomal dominantly inherited epidermolysis bullosa herpetiformis (Dowling-Meara). This is the first reported prenatal diagnosis of EB Dowling-Meara. The morphological criteria of intraepidermal blistering and clumped keratin filaments within basal and immediately suprabasal cells characteristic of an affected individual postnatally also identified an affected fetus. There is, however, insufficient experience to be certain that these findings will hold from region to region in the body or among all affected fetuses, and thus prenatal diagnosis on a morphological basis should still be made with caution.

The distribution of alpha 6 beta 4 integrins in lesional and non-lesional skin in bullous pemphigoid

The alpha 6 beta 4 integrin is associated ultrastructurally with the hemidesmosomes of the basal keratinocytes and with the bullous pemphigoid antigen (BPA), suggesting an important role in adhesion of epidermal cells to the basement membrane. Using an immunofluorescence technique with chain-specific monoclonal antibodies to the alpha and beta subunits we have investigated the distribution of the alpha 6 beta 4 integrin in normal skin (n = 3) and in BP skin (uninvolved, perilesional and lesional) [n = 11]). The findings have been compared with other types of subepidermal blisters and with normal skin split by chemical means (n = 2) and by suction (n = 2). The distribution of alpha 6 beta 4 integrin was compared with that of bullous pemphigoid antigen (BPA) and with other basement membrane zone (BMZ) macromolecules, laminin, collagen type IV, collagen type VII and the BM600 antigen. In uninvolved, perilesional and early pre-blistered lesional BP skin the distribution of both the alpha 6 and beta 4 integrin subunits, BPA laminin, collagen types IV and VII and the BM600 antigen was identical to normal skin, i.e. a linear band in the BMZ. Within BP blisters, both alpha 6 and beta 4 integrin subunits and BPA were absent, except in two blisters in which the integrin expression was retained in the blister roof, despite loss of BPA. The other BMZ components were expressed on the blister floor.(ABSTRACT TRUNCATED AT 250 WORDS)