KF-1 monoclonal antibody defines a specific basement membrane antigen defect in dystrophic forms of epidermolysis bullosa

Immunological mapping in hereditary epidermolysis bullosa

Immunological mapping, an immunofluorescence technique, is currently the method most used to diagnose and differentiate the principal types of hereditary epidermolysis bullosa, since this technique is capable of determining the level of cleavage of this mechanobullous disease.

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.

The epidermal basement membrane: structure, ontogeny and role in disease

Since many dermatological diseases affect the epidermal basement membrane zone (BMZ), there has been intense investigation into the role of epidermal BMZ constituents in various skin diseases, particularly subepidermal skin diseases. The epidermal BMZ consists of four major structural components--the basal cell plasma membrane, the lamina lucida, the lamina densa and the sublamina densa zone, which contains anchoring fibrils. The lamina lucida is composed of laminin, bullous pemphigoid antigen (a disease-specific glycoprotein identified by antibodies circulating in patients' sera), and other as yet poorly defined antigens which are identified by in vivo bound and circulating antibodies in the sera of patients with herpes gestationis, scarring pemphigoid and other conditions. The lamina densa consists of type IV collagen and KF-1 antigen (which is non-collagenous and is identified by a skin-specific monoclonal antibody). Knowledge of the structure and chemical composition of the BMZ is critical to an understanding of some of the genetic and immunologically mediated blistering skin diseases.

Defective in vivo expression and apparently normal in vitro expression of a newly identified 105-kDa lower lamina lucida protein in dystrophic epidermolysis bullosa

We have previously identified a novel 105-kDa lower lamina lucida protein detected by the autoantibodies from a group of patients who developed a unique immune-mediated subepidermal bullous dermatosis. We sought to determine if this novel basement membrane zone (BMZ) protein is normally expressed in the skin of patients with various subsets of epidermolysis bullosa (EB). Indirect immunofluorescence microscopy performed on non-lesional skin sections from patients with three major EB subsets revealed absence or significantly reduced expression of this novel BMZ protein in 20 out of 23 skin sections from patients with generalized dominant and recessive dystrophic EB. However, immunoblot analyses with the autoantibodies on Western-blotted proteins revealed that a comigrating 105-kDa protein is present in both cytosol extracts (n = 6) and conditioned media (n = 3) of cultured dermal fibroblasts derived from patients with dystrophic EB, as well as those cultured from two healthy individuals. Although the reason for such disparate findings is not known, the defective in vivo expression of this novel 105-kDa protein in dystrophic EB is presumably not due to a failure of fibroblasts to synthesize or secrete the protein. It is possible, however, that the 105-kDa protein may be unable to incorporate into the BMZ because it is produced in a dysfunctional form, or its BMZ binding site is missing. It is also possible that other structural alterations in skin BMZ, which occur in dystrophic EB, result in masking of the antigenic binding by the autoantibody when intact BMZ is probed.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered expression of a new antigen of the dermal-epidermal junction (NU-T2 DEJ Ag) in junctional epidermolysis bullosa

NU-T2 antigen (Ag) is a new and recently described antigen of the dermal-epidermal junction, recognized by an anti-CD1b monoclonal antibody denominated NU-T2. We studied NU-T2 Ag expression in junctional epidermolysis bullosa (13 patients) and in other forms of hereditary epidermolysis bullosa (23 patients), comparing the results with nicein expression. In junctional epidermolysis bullosa gravis type no differences were found between the expression of NU-T2 and nicein, both being negative in bullous as well as in non-bullous skin. Interestingly, in mitis type junctional epidermolysis bullosa, NU-T2 Ag was found to be absent or reduced in five of six patients both in lesional and in uncleaved skin. When compared with nicein expression, clearcut differences were found, further suggesting that these two antigens are different. These data confirm that NU-T2 Ag is a novel epitope of the dermal-epidermal junction, probably relevant in dermal-epidermal cohesion, and it could be responsible, together with nicein, 19-DEJ-1 and other adhesion molecules, for the different subtypes of junctional epidermolysis bullosa. Finally, NU-T2 monoclonal antibody is a new relevant tool for the diagnosis, classification, and prenatal diagnosis of junctional epidermolysis bullosa.

Morphology of the basement membrane

The aim of this contribution is to summarize our knowledge of the morphology of the basement membrane (BM). The first step in this direction is the attempt to define this term. The BM is composed of the Lamina lucida, densa, and fibroreticularis. Subsequently, the historical development of this term is discussed. Our main interest is, of course, focused on the description of the BM-structure up to the macromolecular level and the special forms of this structure. This is supplemented by discussing its chemical composition and establishing a relationship between morphology and biochemistry. The obtained findings yielded some indications as to the molecular composition of the BM which may serve for the construction of "models." The composition of the Lamina lucida (L.l.) and the Lamina or Pars fibroreticularis (L.f.) must be discussed separately, since, if present, they show a different and strongly varying structure (L.f.). An important aspect is the function of this extracellular layer which comprises mechanical tasks up to inductive effects. Finally, the concepts of the formation of the BM, especially of the Lamina densa (L.d.), are summarized. It obviously consists of a sequence of individual steps which starts with expression and secretion of the L.d.-components and is followed by an induction of integrin expression.

Proteoglycans in cultures of skin fibroblasts in recessive dystrophic epidermolysis bullosa

The proteoglycans of cultured fibroblasts from the skin of three patients with recessive dystrophic epidermolysis bullosa and three normals were compared after labeling with [35S]sulfate and [3H]leucine. The behavior in gel chromatography of the intact proteoglycans and several properties of their component glycosaminoglycans (size, content of iduronic acid, and content of 4- and 6-sulfate) showed no statistical differences. In addition, the binding of intact proteoglycans and of their constituent proteins and glycosaminoglycans to type I collagen were measured by affinity chromatography. No differences were found that could account for the skin lesions in recessive dystrophic epidermolysis bullosa.

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.

Structure and antigenicity of the skin basement membrane zone

The skin basement membrane zone is comprised of two major ultrastructural regions, four associated structures, and at least 17 different antigens. In this brief review, the ultrastructure, antigenicity, and ontogeny of normal human skin will be discussed in detail, as will alterations in expression or immune response to selected basement membrane components in specific mechanobullous and autoimmune diseases.

Immunoelectron microscopy and immunofluorescence antigenic mapping: diagnostic applications

In selected situations, direct and indirect IEM may provide important diagnostic information for the clinician, as pertains to the diagnosis and therefore prognosis in a given patient. As discussed, however, all of the more conventional approaches should be pursued before consideration is given to the performance of IEM, knowing its relative cost and technical difficulty. In contrast, we consider immunofluorescence antigenic mapping to be the diagnostic method of choice for the determination of the type of inherited EB present in affected individuals. When additional ultrastructural or morphometric data is required, then TEM can be performed as an adjunct study once it is determined by mapping technique that additional useful information may be derived.

Animal model for dermolytic mechanobullous disease: sheep with recessive dystrophic epidermolysis bullosa lack collagen VII

A severe congenital mechanobullous disease with dermolytic blistering and recessive inheritance is described in sheep. The affected animals of wild and inbred flocks of the breed Weisses Alpenschaf (WAS) have blisters of skin, oral mucosa, tongue, and esophagus at birth or within the first week of life. Exungulation occurs early, and severe erosions in the mouth lead to difficulty in feeding. Electron microscopic examination revealed sub-lamina densa splitting in natural or fresh friction blisters and absence of identifiable anchoring fibrils in clinically uninvolved skin. Antigen mapping localized laminin and collagen IV to the blister roof. Indirect immunofluorescence staining with antibodies to collagen VII, the major structural component of the anchoring fibrils, demonstrated a complete absence of reaction in clinically uninvolved tissues of the affected sheep, whereas in normal sheep a strong linear fluorescence was seen at the epithelial-mesenchymal basement membrane zone. Dermal extracts of normal sheep contained intact collagen VII, but epidermal and dermal extracts from the affected sheep lacked this collagen or its fragments in immunoblotting experiments. Based on genetic, clinical, ultrastructural, and immunochemical findings, the sheep disorder corresponds to the severe mutilating subtype of recessive dystrophic epidermolysis bullosa in humans and can be used as an animal model to investigate the human disorder.

Revised clinical and laboratory criteria for subtypes of inherited epidermolysis bullosa. A consensus report by the Subcommittee on Diagnosis and Classification of the National Epidermolysis Bullosa Registry

Inherited epidermolysis bullosa encompasses a number of diseases, with the common finding of blister formation after minor mechanical trauma to the skin. In some forms significant, if not eventually fatal, extracutaneous disease activity may occur. In recent years application of newer technologies has contributed substantially to an overall understanding of this collection of inherited diseases. Concurrently, many new phenotypes have been recognized, in part the result of ongoing prospective patient registries in the United States and abroad. Unfortunately, this has resulted in a massive literature that may appear to be confounded by seemingly excessive or arbitrary subdivision of epidermolysis bullosa variants. With these concerns in mind a subcommittee was established by the National Epidermolysis Bullosa Registry to summarize the current literature and to make recommendations as to the best clinical and laboratory criteria for the practical diagnosis and subclassification of patients with inherited epidermolysis bullosa.

Expression of integrins in junctional and dystrophic epidermolysis bullosa

Recently, monoclonal antibodies (MoAb) have been raised against a family of adhesive membrane receptors (R) for extracellular matrix molecules known as integrins. In order to ascertain whether these adhesive proteins are normally expressed in inherited epidermolysis bullosa (EB) dermal epidermal junction, we studied the reactivity of MoAb recognizing receptors for VLA-1 (R for unknown ligand), VLA-2 (R for collagen), VLA-3 (R for collagen, laminin, fibronectin), VLA-4 (R for unknown ligand), VLA-5 (R for fibronectin), VLA-6 (R for laminin), VNR alpha, and VNR beta (R for vitronectin) on cryostat skin sections from EB patients and normal controls and on cytospins of normal epidermal cell suspensions with indirect immunohistochemical methods. Two cases of junctional EB (EBj) (lethal and non-lethal), three cases of dominant dystrophic EB (EBdd), two cases of recessive dystrophic EB (EBdr), and two normal controls skin sections and cell suspensions entered the study. No significant modification of the distribution of these adhesive receptors was observed in junctional and dystrophic EB skin. Both in normal and EB specimens MoAb against VLA-2, VLA-3, and VNR alpha determinants showed reactivity with the total cytoplasmic membrane of basal keratinocytes and basement membrane zone. Interestingly, anti-VLA-6 MoAb was characterized by an intense linear staining of the dermal-epidermal junction with the same localization on the roof of the blisters in EBj, EBdd, and EBdr as bullous pemphigoid (BP) serum. On the basis of these results we suggest that anti-VLA-6 MoAb could be used instead of BP serum for immunohistochemical detection of the cleavage of blisters in EB.

Applicability of 19-DEJ-1 monoclonal antibody for the prenatal diagnosis or exclusion of junctional epidermolysis bullosa

Recently a monoclonal antibody (19-DEJ-1) was produced with binding specificity for the mid-lamina lucida of the skin dermo-epidermal junction, in very close association with overlying hemidesmosomes. Since skin cleavage occurs within the lamina lucida in the inherited blistering disorder, junctional epidermolysis bullosa (EB), and is associated with aberrations in the morphology and/or number of hemidesmosomes in such tissue, we have sought to determine whether this monoclonal antibody could be used for prenatal diagnosis. Fetoscopy-directed skin biopsies were obtained from two fetuses at risk for junctional EB and post-mortem samples from two other fetuses with the Herlitz type of junctional EB, the latter after prenatal diagnosis by electron microscopy and termination of each pregnancy. Specimens were examined in part by light and electron microscopy for evidence of skin cleavage or other alterations in morphology, and in part by indirect immunofluorescence for altered basement membrane antigenicity. Three of four fetuses were shown to have intra-lamina lucida blister formation indicative of, and hemidesmosome hypoplasia proving, junctional EB. Each was also shown to lack expression of GB3 and 19-DEJ-1 antigens, consistent with findings noted postnatally in junctional EB; diagnosis was confirmed in each at the time of therapeutic abortion. A fourth fetus had no abnormalities detected; lack of disease involvement was confirmed at the time of delivery, and subsequently over 8 months of careful serial evaluation. We conclude that 19-DEJ-1 monoclonal antibody is an accurate and sensitive immunohistochemical probe for junctional EB, and may be employed in the prenatal diagnostic evaluation of fetuses at risk for this disorder.

Basement membrane heterogeneity and variation in corneal epithelial differentiation

We have previously shown that the expression of a major 64-Kda keratin (K3) in corneal epithelium is site-related. It is found suprabasally in limbal epithelium, but uniformly (basal cells included) in central corneal epithelium. In the present study, we used a panel of antibodies against various components of corneal epithelial basement membrane to investigate a possible correlation between basement membrane heterogeneity and differential (basal vs. suprabasal) K3 keratin expression. One of these antibodies, AE27, stains human conjunctival basement membrane weakly, limbal basement membrane heterogeneously, and central corneal basement membrane strongly. Basal cells resting on basement membrane that stains strongly with AE27 tend to stain with monoclonal antibody AE5, which recognizes keratin K3. Basal cells on basement membrane staining weakly with AE27 tend not to stain with AE5. No such correlation exists between AE5 staining and type IV collagen, which is detectable immunohistochemically in conjunctival and limbal basement membrane, but not in corneal basement membrane overlying Bowman's layer. These results suggest that basement membrane of human corneal/conjunctival epithelium can be divided into at least three domains: the conjunctival basement membrane (type IV collagen-positive, AE27-weak), the limbal basement membrane (type IV collagen-positive, AE27-strong), and corneal basement membrane (type IV collagen-negative, AE27-strong). The results also raise the possibility that basement membrane heterogeneity may play a functional role in regulating keratin expression and other aspects of differentiation of corneal epithelium; more experiments are needed to test this hypothesis.

Entactin: ultrastructural localization of an ubiquitous basement membrane glycoprotein in mouse skin

Entactin is a recently described sulfated glycoprotein component of mouse endodermal cell-derived extracellular matrix and is present in a number of basement membranes. It has been ultrastructurally localized to both lamina densa and adjacent epithelial cell membranes in rodent kidney. In the present study, we have sought to determine the localization of entactin in mouse skin. Indirect immunofluorescence and immunoelectron microscopy (the latter via immunoperoxidase technique) were performed on both intact and NaCl-separated mouse skin, using a well-characterized IgG class entactin-specific rat x mouse monoclonal antibody. At the light microscopic level, entactin was present in all skin basement membranes. On NaCl-split skin, staining was noted solely on the dermal portion. At the electron microscopic level, in intact skin, entactin was primarily localized to the lamina densa and adjacent upper papillary dermis. However, smaller amounts of immunoreaction products were also detectable within the lamina lucida and in close apposition to overlying hemidesmosomes. In partially separated skin, immunoreactants were similarly noted above the level of the lamina densa. However, in completely separated areas, hemidesmosomal or cell membrane staining was no longer visible. We conclude that entactin is an ubiquitous component of mouse skin basement membranes. Similar to previous findings in rodent kidney, entactin is present in multiple regions of skin basement membrane, although its primary localization remains within and directly beneath the lamina densa.

Epidermolysis bullosa simplex with mottled pigmentation

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.

Anchoring fibrils and type VII collagen are absent from skin in severe recessive dystrophic epidermolysis bullosa

Skin of patients with severe generalized recessive dystrophic epidermolysis bullosa (SGRDEB) was studied by immunoelectron microscopy and immunoblotting with antibodies to type VII collagen, a major structural component of anchoring fibrils. In normal skin, the protein was localized to the dermoepidermal junction zone below the basement membrane and was extractable from the papillary dermis after artificial epidermolysis. In SGRDEB skin, neither immunoreactive material below the basement membrane nor identifiable anchoring fibrils could be recognized and neither the tissue form nor the specific proteolytic fragments of type VII collagen were found in extracts of SGRDEB skin. Very low amounts of type VII collagen alpha-chains could be detected in cultures of SGRDEB-fibroblasts, whereas normal fibroblasts synthesized more of this collagen. These results suggest that a genetic defect in the correct synthesis, secretion, or in the molecular assembly of type VII collagen may underlie SGRDEB.

Detection and partial characterization of a midlamina lucida-hemidesmosome-associated antigen (19-DEJ-1) present within human skin

A murine anti-human monoclonal antibody (19-DEJ-1) has been produced that binds to basement membranes (BMs) of the dermoepidermal junction and arrector pili muscles but not to either dermal glandular or vascular BMs. 19-DEJ-1 also recognizes BMs underneath epithelia of buccal mucosa, tongue, esophagus, cervix, and cornea, and BMs surrounding smooth muscle in medium-sized vessels, placenta, uterus, and esophagus. When 16 human fetal skins (aged 54-142 gestational days) were examined, the antigen was first detected at 81 days. Using immunoperoxidase and immunogold staining techniques, indirect immunoelectron microscopy demonstrated localization of 19-DEJ-1 to the level of the midlamina lucida, directly underneath hemidesmosomes; absent staining was noted beneath melanocytes. 19-DEJ-1 antigen was detectable in unfixed A431 cells grown on coverslips. After radioincorporation of 35S-methionine into A431 cells, 19-DEJ-1 monoclonal antibody specifically precipitated 2.75% of the total radiolabeled proteoglycans produced in culture supernatant and isolated by anion exchange chromatography. On the basis of our present findings, we conclude that 19-DEJ-1 monoclonal antibody defines a unique primate-specific proteoglycan that is present within BMs along the epithelial-connective tissue interface and around smooth muscle in skin and other selected organs. Its unique ultrastructural localization suggests the possibility that 19-DEJ-1 may recognize an antigenic epitope of either anchoring filaments or alternatively, the subbasal dense plate.

Chondroitin 6-sulfate proteoglycan but not heparan sulfate proteoglycan is abnormally expressed in skin basement membrane from patients with dominant and recessive dystrophic epidermolysis bullosa

Two distinct groups of proteoglycans, chondroitin 6-sulfate (C6-S) proteoglycan and heparan sulfate proteoglycan (HSPG), have been recently shown to reside within the lamina densa of normal human skin basement membrane (BM). To determine whether either or both antigens are normally expressed in one or more forms of epidermolysis bullosa (EB), a disease known to have specific alterations in skin BM, we have examined by indirect immunofluorescence 31 specimens of clinically normal skin from 28 EB patients (simplex, 5; junctional, 8; dominant dystrophic [DDEB], 9; recessive dystrophic [RDEB], 9) with monoclonal antibodies to C6-S and HSPG. HSPG was normally expressed in all EB and control skin specimens, whereas C6-S was absent along the dermoepidermal junction of 9 of 9 RDEB and 7 of 9 DDEB, and reduced in 2 of 9 DDEB cases. In contrast, C6-S was normally expressed in 5 of 5 EB simplex, 5 of 6 junctional EB, and all control skin specimens. We have subsequently extracted a greater than 400 kD C6-S proteoglycan from normal skin BM and have found that the core protein may also contain heparan sulfate side chains. Our findings suggest that 3B3 monoclonal antibody recognizes a hybrid proteoglycan in human skin, and that its absent or reduced binding in dystrophic EB skin BM may reflect either absence of associated core protein or posttranslational alterations in the proteoglycan side chains.

The eye in dystrophic epidermolysis bullosa: clinical and immunopathological findings

The ocular findings in a series of patients with dystrophic epidermolysis bullosa are presented. An immunopathological technique using monoclonal antibodies for examining components of the epithelial basement membrane of the conjunctiva is described and the results obtained on a conjunctival biopsy from a patient with dystrophic epidermolysis bullosa are presented.

Collagenase expression in skin fibroblasts from families with recessive dystrophic epidermolysis bullosa

The collagenase production of cultured skin fibroblasts from Scandinavian families with dominant (D-EBD) and recessive (R-EBD) epidermolysis bullosa dystrophica has been investigated. Heterogeneity as a result of body location origin has been ruled out as fibroblasts obtained from predilection sites produce the same amount of immunoreactive collagenase as those obtained from non-predilection sites of the same subjects. Large variations in in vitro collagenase production were found between individuals and families. Within the R-EBD group, four out of eighteen patients showed an in vitro elevated level of immunoreactive collagenase compared to their healthy relatives, other EB types, and the control group. This shows that an in vitro elevated collagenase production is not a marker for the entire disease group and that the disease denoted as R-EBD probably is etiologically and pathogenetically heterogeneous.

Prenatal diagnosis of dominant and recessive dystrophic epidermolysis bullosa: application and limitations in the use of KF-1 and LH 7:2 monoclonal antibodies and immunofluorescence mapping technique

Prenatal diagnosis is now possible for junctional and recessive dystrophic forms of epidermolysis bullosa (EB); however, there is no similar published experience for dominant dystrophic EB, although data with KF-1 monoclonal antibody suggests that both forms of dystrophic EB can be identified at least postnatally with this unique probe. We now report our experience with light microscopy, electron microscopy, immunofluorescence mapping, and KF-1 and LH 7:2 monoclonal antibodies, in both a mother with dominant dystrophic EB and her fetus at risk, and in a fetus previously shown to be affected with recessive dystrophic EB. KF-1 and LH 7:2 antigens were absent in recessive dystrophic EB fetal skin, identical to findings observed postnatally. LH 7:2 was normally expressed in a mother with dominant dystrophic EB and in her fetus at risk for this disease. In contrast, while KF-1 antigen was abnormally expressed in the affected mother, it was normally expressed in only 1/7 fetal biopsies despite the fact that this fetus was shown by light and electron microscopy and immunofluorescence mapping to be unaffected with dominant dystrophic EB. We conclude that 1) transmission electron microscopy can be used to prenatally exclude the diagnosis of dominant dystrophic EB (Cockayne-Touraine variety), 2) immunofluorescence mapping is an accurate technique for prenatal as well as postnatal diagnosis of EB, and 3) KF-1 cannot by itself be used as an accurate probe for the prenatal diagnosis of dominant dystrophic EB, due to the apparent variability in the time for the normal expression of KF-1 in fetal skin during the second trimester.

Autoantibodies to extracellular collagen matrix components in epidermolysis bullosa and other bullous diseases

In order to determine whether autoantibodies are present in sera from normal individuals and/or patients with selected bullous disorders, a highly sensitive solid-phase radioimmune assay was established using purified native collagen types I-VI, laminin, and fibronectin as substrates. Sixty-four sera were utilized, representing 12 normal controls as well as 4 patients with extensive thermal burns, 18 with autoimmune bullous diseases (11 bullous pemphigoid, 5 pemphigus vulgaris, and 2 epidermolysis bullosa acquisita), and 30 with non-autoimmune mechanobullous diseases [epidermolysis bullosa (EB): 20 simplex, 4 junctional, and 6 dystrophic]. In general, autoantibodies to types I, II and VI collagen and fibronectin were undetectable in any of the patient or control groups. In contrast, autoantibodies to types III and V collagen were noted in 87.5% (28/32) and 90.6% (29/32) of EB sera, respectively, while being only rarely noted in sera from other patient groups. Similarly, autoantibodies to type IV collagen and laminin were detected in 50% (16/32) and 40.6% (13/32) of EB sera, especially from patients with simplex and dystrophic forms of the disease. These data suggest that selected interstitial and basement membrane-associated collagens and laminin may become autoimmunogenic in all three forms of inherited EB in contrast to their relative lack of immunogenicity in at least some of the other intraepidermal and subepidermal blistering disorders. The role, if any, of these autoantibodies in the induction or perpetuation of blistering in EB awaits further studies.

Protease inhibitor therapy for recessive dystrophic epidermolysis bullosa. In vitro effect and clinical trial with camostat mesylate

Recently we reported that a kind of serine protease, SH protease, and collagenase might be involved in blister formation and, furthermore, that the cooperative action of these three proteases was essential for blister formation in recessive dystrophic epidermolysis bullosa. In this study we examined the inhibitory effect of clinically usable serine protease inhibitors for blister formation in organ culture and in clinical trials of recessive dystrophic epidermolysis bullosa patients. Camostat mesylate, a synthetic serine protease inhibitor that is available for the treatment of chronic pancreatitis, demonstrated a striking effect of inhibiting blistering in organ culture of normal human skin with recessive dystrophic epidermolysis bullosa blister fluids. Subsequently we administered camostat mesylate by topical application to four patients with recessive dystrophic epidermolysis bullosa to assess its ability to reduce blistering. Therapeutic response was favorable; a significant effect in decreasing the number of blisters was observed in three of four patients. These findings actually supported the hypothesis that a kind of serine protease had a close relationship with blistering in recessive dystrophic epidermolysis bullosa and that therapy with a clinically usable protease inhibitor was useful for the treatment of this disease.

Ontogeny of structural components at the dermal-epidermal junction in human embryonic and fetal skin: the appearance of anchoring fibrils and type VII collagen

The ontogeny and composition of the dermal-epidermal junction (DEJ) in developing human embryonic and fetal skin was studied at progressive stages of gestation by immunofluorescence microscopy and immunocytochemistry using transmission electron microscopy (TEM). The DEJ of embryonic skin at 5 weeks estimated gestational age (EGA) was a simple basement membrane zone limited to the basal cell plasma membrane, lamina lucida, and lamina densa. A network of reticular collagen fibrils (reticular lamina) was deposited beneath the lamina densa by 6 weeks. Coincident with the onset of increased complexity in epidermal and dermal structure, at the time of the embryonic to fetal transition, the DEJ displayed additional components that were markers of maturation. At 7-8 weeks EGA, fine filamentous structures extended from the DEJ into the reticular lamina. By 9 weeks EGA hemidesmosomes and banded anchoring fibrils were recognizable, although distributed sparsely at the DEJ. With increasing gestational age, these structures displayed greater electron density and structural completeness. By the end of the first trimester, the DEJ appeared ultrastructurally similar to that of mature skin. Weak immunofluorescent labeling demonstrated the presence of type VII collagen at the DEJ by 8 weeks EGA. From 10-12 weeks EGA immunofluorescent labeling of the DEJ for type VII collagen was distinctly punctate, while immunoperoxidase labeling observed by TEM was linear, continuous, and sublamina densa in position. With ongoing gestation the immunofluorescent labeling became increasingly stronger at the DEJ. Thus, type VII collagen was present at the DEJ in the zone immediately beneath the lamina densa, before the appearance of mature anchoring fibrils but coordinate with the appearance of fine filamentous, unbanded structures, and appeared to increase with the development and accumulation of anchoring fibrils.

Nidogen and heparan sulfate proteoglycan: detection of newly isolated basement membrane components in normal and epidermolysis bullosa skin

The epidermal basement membrane zone comprises various biochemical constituents, some of which may be affected or involved in certain forms of mechanobullous diseases. Recently, nidogen and a low density form of heparan sulfate proteoglycan--two ubiquitous, noncollagenous components of basement membranes--were isolated and characterized, and affinity-purified antibodies to each component were prepared. These antibodies were used to study the distribution of both antigens in normal and diseased human skin. By immunofluorescence, both nidogen and heparan sulfate proteoglycan were linearly distributed along the basement membrane of the dermal-epidermal junction, adnexal structures, and blood vessels of normal human skin. On suction-induced blisters of normal skin, both antigens were found at the base of the blister, indicating that each was within or below the lamina lucida. By indirect immunoelectron microscopy, both antigens were ultrastructurally located within the lamina densa. The staining patterns for nidogen and heparan sulfate proteoglycan were examined in 11 patients with either junctional, dominant dystrophic, or recessive dystrophic epidermolysis bullosa, and were found to be not different from the patterns observed in normal skin.

Autosomal dominant epidermolysis bullosa dystrophica: are the Cockayne-Touraine, the Pasini and the Bart-types different expressions of the same mutant gene?

We report on a family with autosomal dominant dystrophic epidermolysis bullosa and congenital localized absence of skin, resembling the features of Bart's Syndrome. This type of epidermolysis bullosa and the Cockayne-Touraine and Pasini types may represent different expressions of the same gene defect.

Morphogenesis and malformations of the skin NICHD/NIADDK research workshop

Developmentally caused skin malformations constitute a spectrum of birth defects, some of which can be recognized prenatally by morphologic or biochemical means. The number of prenatally diagnosable skin diseases could be greatly expanded with an increased understanding of the molecular and cellular bases of skin development and the mechanisms that result in the generation of skin defects. The National Institute of Child Health and Human Development and the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, therefore, sponsored a workshop that recommended basic biologic studies combined with clinical investigations of normal and abnormal cutaneous development set forth in this article. Investigations resulting from these research recommendations are intended to contribute to the knowledge that should aid in the prevention of developmentally caused skin deformities.

Antenatal diagnosis of recessive dystrophic epidermolysis bullosa: collagenase expression in cultured fibroblasts as a biochemical marker

We performed fetoscopy and skin biopsy on a 19-week fetus at risk for recessive dystrophic epidermolysis bullosa (RDEB). Ultrastructural analysis of the tissue revealed dermolytic blister formation in the skin characteristic of the disease. To develop a biochemical test for use in antenatal diagnosis of RDEB, we established skin fibroblast cultures from the 20-week aborted fetus. The collagenase production by fetal RDEB fibroblast cultures was greater than seen in normal fetal fibroblast cultures. The concentration in culture medium from fetal RDEB cultures was 5.42 +/- 0.74 micrograms/ml (mean +/- SE) compared with 2.24 +/- 1.11 micrograms/ml in normal adult control cultures and 2.05 +/- 0.61 micrograms/ml in cultures from patients with other genetic forms of epidermolysis bullosa (p less than 0.025). In contrast, the concentration of collagenase in the fetal RDEB culture medium was not different from that seen in cell cultures from known patients with RDEB (5.34 +/- 1.12 micrograms/ml). Collagenase activity of the fetal RDEB medium was also increased approximately 3.5-fold. These data indicate that enhanced expression of collagenase by fetal RDEB skin fibroblasts can serve as a biochemical adjunct, and possibly an alternative, to morphologic examination of tissue for antenatal diagnosis.

Identification of an epidermal basement membrane defect in recessive forms of dystrophic epidermolysis bullosa by LH 7:2 monoclonal antibody: use in diagnosis

LH 7:2 is a monoclonal antibody that was raised against an extract of human epidermal cells and identifies an epitope within the lamina densa of the basement membrane of stratified squamous epithelia. Using indirect immunofluorescence we found intense labelling with LH 7:2 at the epidermal basement membrane (EBM) of normal skin, and in skin samples from patients with simplex, junctional, dominantly inherited dystrophic and acquired forms of epidermolysis bullosa (EB), as well as bullous pemphigoid. Staining was absent or only very faint in generalized recessive dystrophic EB (RDEB), and patchily reduced in the localized form of RDEB. We conclude that LH 7:2 recognizes an EBM antigen which may be important in the pathogenesis of RDEB. Moreover, the antibody provides a useful probe for the rapid diagnosis of RDEB and is of special value in helping to discriminate between localized RDEB and typical dominant dystrophic EB--conditions which closely resemble each other clinically and which cannot be distinguished by means of transmission electron microscopy.

Biochemical characterization of the epithelial basement membrane antigen defined by the monoclonal antibody KF-1

The KF-1 monoclonal antibody has been shown to identify a noncollageneous component of the lamina densa of the basement membrane zone of human skin. In the present work, the monoclonal antibody and the antigen were further characterized. KF-1 monoclonal antibody is an IgG3 immunoglobulin with no binding to staphylococcal protein A. Two squamous carcinoma cell lines--namely, TR131 and TR146--quantitatively express the antigen. Immunofluorescence techniques showed that the antigen is a cell surface antigen, is sensitive to Triton X-100 extraction, and is concentrated in cell areas from which actin fibers are excluded. Immunoblot analysis showed that this monoclonal antibody identifies a 72 kD polypeptide present in TR131 cell extract as well as in cultured human keratinocyte cell extract.

LDA-1: a ubiquitous noncollagenous lamina densa component of basement membrane detected by monoclonal antibody technique

Using monoclonal antibody technology, a new basement membrane antigen, designated as LDA-1, has been identified. This antigen is expressed in all human tissues thus far examined; within skin it is detectable not only within the dermal-epidermal junction but also within dermal vascular and appendageal basement membranes. In addition to human skin, LDA-1 is also detectable within rabbit but not monkey, rat, mouse, guinea pig, or cow skin. This antigen has been ultrastructurally localized to the lamina densa and to a much lesser extent, the adjacent sublamina densa region. ELISA (enzyme-linked immunosorbent assay) revealed no cross-reactivity between LDA-1 and type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan. In vitro enzymatic studies suggest that LDA-1 is noncollagenous in nature.

Bart's syndrome: microscopic, ultrastructural, and immunofluorescent mapping features

Bart's syndrome has been clinically described as the association of congenital localized absence of skin (CLAS), epidermolysis bullosa (EB), oral mucosal lesions, and dystrophic nails. Transmission occurs through an autosomal dominant gene with complete penetrance but variable expression. It has been difficult to classify this type of EB because of lack of microscopic and ultrastructural studies on affected family members. This is the first report of microscopic, ultrastructural, and immunofluorescent mapping studies of an affected individual with the complete inherited syndrome initially described by Bart. This study is also the first to document the association of CLAS and dominant dystrophic epidermolysis bullosa by histology, electron microscopy, and immunofluorescent mapping. Our two patients and one other affected family member had diminution or absence of a specific basement membrane antigen as defined by immunofluorescence with a monoclonal antibody (KF-1) in perilesional skin.

Origin and properties of the blister formation factor in blister fluids from recessive dystrophic epidermolysis bullosa

The origin and properties of the blister formation factor in recessive dystrophic epidermolysis bullosa (RDEB) blister fluids were investigated. Organ cultures of normal human skin incubated with RDEB dermis extract or with RDEB fibroblast culture medium (FCM) produced a clear subepidermal blister with histology similar to that of a RDEB blister in vivo. The injection of RDEB dermis extract into guinea-pig skin also induced dermal-epidermal separation with similar histology to the skin lesions of RDEB patients. The blister forming activity of RDEB FCM which induces the subepidermal blister was inactivated by heat (60 degrees C for 30 min), trypsin digestion and by treating with EDTA, EGTA, alpha 2-macroglobulin, diisopropyl fluorophosphate and N-ethylmaleimide, but was not affected by dialysis. These results suggest that the RDEB fibroblast produces a blister formation factor(s), and that blister formation may be caused by a combination of a metallo-protease, serine protease and SH protease.

Monoclonal antibodies and the skin biopsy: current and potential clinical applications

Monoclonal antibodies are becoming increasingly useful in the clinical diagnosis and/or treatment of a number of unrelated diseases. Discussion will be directed to those monoclonal antibodies recognizing antigens within the skin which appear to have either proven or potential application in the diagnostic evaluation of the skin biopsy.

A study of the dermo-epidermal junction in dystrophic epidermolysis bullosa using the periodic acid-thiosemicarbazide-silver proteinate technique

Dermo-epidermal separation in dystrophic epidermolysis bullosa (DEB) is thought to results from an abnormality of anchoring fibrils which, in normal skin, are stained selectively by the periodic acid-thiosemicarbazide-silver proteinate technique. This method was applied to non-lesional skin from four patients with generalized recessive DEB, five with localized recessive DEB and one with dominant DEB. No anchoring fibrils were present in the subjects with generalized recessive DEB, but they were morphologically normal in the case of dominant DEB and in three patients with mild localized recessive DEB. Two patients with a more severe form of localized recessive DEB possessed attenuated anchoring fibrils which lacked the normal banding of the mid-portion. The lamina densa, normally unlabelled, was consistently stained in patients with generalized recessive DEB, suggesting a biochemical abnormality of this structure.