Preventive but Not Therapeutic Topical Application of Local Anesthetics Can Inhibit Experimental Epidermolysis Bullosa Acquisita in Mice

Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disorder characterized and caused by autoantibodies against type VII collagen (COL7). Although it has been noticed that EBA in both patients and mice is associated with an increased scratching, it is not clear whether and how the scratching contributes to disease manifestation. Hence, we here aimed to validate this clinical observation and also to investigate the potential contribution of increased scratching in EBA pathogenesis in mice. Longitudinal assessment of scratching behavior revealed an increased frequency of scratching as early as 12 hours after injection of anti-COL7 IgG into the skin of mice. Subsequently, scratching events became even more frequent in mice. In contrast, mice injected with a control antibody showed an unaltered scratching behavior throughout the observation period. Based on these observations, we hypothesized that mechanical irritation may promote the induction of inflammation in experimental EBA. To challenge this assumption, the local anesthetic dyclonine hydrochloride was topically applied before injection of anti-COL7 IgG. Dyclonine hydrochloride reduced the scratching events and impaired clinical disease manifestation. In therapeutic experimental settings, i.e. administration of the local anesthetic 24 hours after injection of anti-COL7 IgG, dyclonine hydrochloride only inhibited the scratching behavior, but had no significant effect on clinical disease development. In addition, eosinophils were detected in the skin before the injection of anti-COL7 IgG and significantly increased 48 hours after the antibody injection. Collectively, our results suggest that scratching behavior contributes to the initiation phase of disease manifestation in experimental EBA.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

Epidermolysis Bullosa (EB) Acquisita in an Adult Patient with Previously Unrecognized Mild Dystrophic EB and Biallelic COL7A1 Mutations

Circulating anti-type VII collagen autoantibodies are frequently detected in patients with recessive dystrophic epidermolysis bullosa (RDEB). However, evidence supporting their pathogenic role in inducing epidermolysis bullosa acquisita (EBA) has been provided for only one individual with dominant dystrophic epidermolysis bullosa (DDEB). We describe here a patient who presented with dystrophic toenails since early childhood and developed trauma-induced skin blisters and oral erosions at age 26 years. Direct immunofluorescence showed IgG deposits with a u-serrated pattern along the cutaneous basement membrane zone, while no change in the expression of collagen VII could be detected by antigen mapping. High-titre anti-collagen VII antibodies were detected by enzyme-linked immunoassay (ELISA). In parallel, sequencing of epidermolysis bullosa (EB) genes identified compound heterozygous COL7A1 missense c.410G>A (p.Arg137Gln) and splicing c.3674C>T (p.Ala1225_Gln1241del) mutations, previously unrecognized in dystrophic epidermolysis bullosa (DEB). Thus, our patient had RDEB "nails-only" and developed mechanobullous EBA in adulthood. These data support a pathogenic role of circulating autoantibodies to collagen VII in inducing EBA in selected patients with DEB. Unforeseen worsening of skin symptoms in DEB should prompt laboratory investigations for EBA.

Case of epidermolysis bullosa acquisita with concomitant anti-laminin-332 antibodies

Subepidermal autoimmune blistering disease including bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, anti-laminin-γ1 pemphigoid, linear immunoglobulin A bullous disease and epidermolysis bullosa acquisita (EBA), are all characterized by direct immunofluorescence microscopy or immunoglobulin deposition on the basement membrane zone. Among them, EBA is a rare acquired subepidermal autoimmune blistering disease of the skin and mucous membranes reactive with type VII collagen, a major component of the epidermal basement membrane zone. Anti-laminin-332-type mucous membrane pemphigoid has pathogenic autoantibodies against laminin-332, which is a basement membrane heterotrimeric protein composed of α3, β3 and γ2 laminin chains. We describe a 73-year-old Japanese man presenting with multiple, annular, tense blisters on the lower legs and oral lesions. Despite the severe clinical manifestations, the disease was successfully controlled by combination therapy of oral prednisolone and mizoribine. This case was confirmed to have autoantibodies to both type VII collagen and laminin-332 α3 chain by indirect immunofluorescence of 1 mol NaCl-split normal human skin, various immunoblot analyses and enzyme-linked immunosorbent assays. This case was a rare case of EBA with concomitant anti-laminin-332 antibodies.

Structural proteins of the dermal-epidermal junction targeted by autoantibodies in pemphigoid diseases

The dermal-epidermal junction consists of a network of several interacting structural proteins that strengthen adhesion and mediate signalling events. This structural network consists of hemidesmosomal-anchoring filament complexes connecting the basal keratinocytes to the basement membrane. The anchoring filaments in turn interact with the anchoring fibrils to attach the basement membrane to the underlying dermis. Several of these structural proteins are recognized by autoantibodies in pemphigoid diseases, a heterogeneous group of clinically and immunopathologically diverse entities. Targeted proteins include the two intracellular plakins, plectin isoform 1a and BP230 (also called bullous pemphigoid antigen (BPAG) 1 isoform e (BPAG1e)). Plectin 1a and BP230 are connected to the intermediate filaments and to the cell surface receptor α6β4 integrin, which in turn is connected to laminin 332, a component of the anchoring filaments. Further essential adhesion proteins are BP180, a transmembrane protein, laminin γ1 and type VII collagen. Latter protein is the major constituent of the anchoring fibrils. Mutations in the corresponding genes of these adhesion molecules lead to inherited epidermolysis bullosa emphasizing the importance of these proteins for the integrity of the dermal-epidermal junction. This review will provide an overview on the structure and function of the proteins situated in the dermal-epidermal junction targeted by autoantibodies.

Sublamina densa-type linear IgA bullous dermatosis with IgA autoantibodies specific for type VII collagen: a case report and clinicopathological review of 32 cases

Linear IgA bullous dermatosis (LABD) is a rare autoimmune bullous disorder characterized by linear deposits of IgA at the basement membrane zone(BMZ) and/or by circulating IgA anti-BMZ antibodies. Comparing with other immuno-bullous diseases, LABD represents a heterogeneous disease entitywith diversity of pathogenic IgA autoantibodies to different hemidesmosomal antigens and an association with malignancies and occasional drug use. We herein present an 82-year-old Japanese man with LABD, whose indirect immunofluorescence using 1M NaCl-split skin showed positive staining for IgA at the dermal side alone. Fluorescence overlay antigen mapping using laser scanning confocal microscopy (FOAM-LSCM) was employed to examine the in vivo bound patient's IgA, which was specific for type VII collagen (COL7), a prominent antigen of the sublamina densa. One year later, he developed malignant lymphoma, suggesting the diagnosis of paraneoplastic LABD. We reviewed 32 cases of sublamina-densa type LABD with anti-COL7 IgA antibodies thus far reported in the literature to compare the clinicopathological characteristics of this rare disease variant and emphasize that COL7 is the main autoantigen in sublamina densa disease.

Autoimmunity and Cytokine Imbalance in Inherited Epidermolysis Bullosa

In order to evaluate the serum anti-skin autoantibodies and cytokine concentrations in patients with different epidermolysis bullosa (EB) types and severity, 42 EB patients and 38 controls were enrolled. Serum anti-skin antibodies were significantly higher in the patients than in the controls (p = 0.008, p < 0.001, p < 0.001, p < 0.001 and p < 0.001 for desmoglein 1 (DSG1) desmoglein 3 (DSG3), bullous pemphigoid 180 (BP180), BP230 and type VII collagen (COL7), respectively). The same trend was observed for interleukin (IL)-1β, IL-2, IL-6, IL-10, tumor necrosis factor-β, and interferon-γ (p < 0.001, p < 0.001, p < 0.001, p = 0.008, p < 0.001 and p = 0.002, respectively). Increases in anti-skin antibodies and cytokine concentrations were higher in patients with recessive dystrophic EB than in those with different types of EB, in generalized cases than in localized ones, and in patients with higher Birmingham Epidermolysis Bullosa Severity (BEBS) scores than in those with a lower score. The BEBS score was directly correlated with BP180, BP230, COL7 (p = 0.015, p = 0.008 and p < 0.001, respectively) and IL-6 (p = 0.03), whereas IL-6 appeared significantly associated with DSG1, DSG3, BP180, BP230 and COL7 (p = 0.015, p = 0.023, p = 0.023, p = 0.015 and p = 0.005, respectively). This study showed that autoimmunity and inflammatory responses are frequently activated in EB, mainly in severe forms, suggesting the use of immunosuppressive drugs or biologicals that are active against pro-inflammatory cytokines to reduce clinical signs and symptoms of disease.

Autoantibody Profile of a Cohort of 78 Italian Patients with Mucous Membrane Pemphigoid: Correlation Between Reactivity Profile and Clinical Involvement

Direct diagnosis of mucous membrane pemphigoid (MMP) is not easy. Circulating autoantibodies targeting bullous pemphigoid antigens of 180 kDa and 230 kDa (BP180 and BP230), α6β4 integrin, laminin 332 and type VII collagen (Col VII) are not always present. The aims of this study were to characterize the humoral immune response of a cohort of Italian patients with MMP, its association with clinical involvement and severity, and to design an algorithm for efficient serological diagnosis. Seventy-eight MMP sera were studied retrospectively by indirect immunofluorescence on salt-split skin, enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Indirect immunofluorescence on salt-split skin resulted in the most sensitive approach for diagnosis of MMP. BP180 was the major autoantigen in MMP patients with oral and cutaneous involvement. Significant associations were found between BP180 reactivity and oral and cutaneous localization of the lesions (p = 0.006), and between Col VII positivity and Setterfield severity score (p = 0.020).

The use of Biochip immunofluorescence microscopy for the serological diagnosis of epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita is a rare autoimmune bullous disease characterized by the presence of circulating antibodies directed against the collagen type VII. Diagnosis is generally based on clinical history, clinical features, histology, direct and indirect immunofluorescence, immunoblotting and ELISA. Our study aims to determine the validity of the Biochip immunofluorescence microscopy for the serological diagnosis of epidermolysis bullosa acquisita. Six patients with epidermolysis bullosa acquisita and presence of antibodies against type VII collagen confirmed by ELISA were included in the study. Subsequently, all sera of patients were analyzed using Biochip. Antibodies anti-collagen type VII were detected in all sera by means of the Biochip technology. Thus, Biochip shows a good correlation with ELISA and seems to be an appropriate method for the diagnosis of epidermolysis bullosa acquisita. It is an easy, fast and standardized method which could facilitate the diagnosis of this autoimmune bullous disease. We suggest that it could be used as an initial screening test to identify patients with epidermolysis bullosa acquisita.

Diagnostic performance of the "MESACUP anti-Skin profile TEST"

BACKGROUND

The "MESACUP anti-Skin profile TEST" is a new, commercially available ELISA kit to detect circulating IgG autoantibodies against desmoglein 1, desmoglein 3, BP180, BP230, and type VII collagen, both simultaneously and more rapidly than previous assays.

OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy of this kit for the diagnosis of pemphigus foliaceus, pemphigus vulgaris, bullous pemphigoid and epidermolysis bullosa acquisita.

MATERIALS & METHODS

Dual-centre retrospective study in which 138 patients with autoimmune blistering diseases were compared to 40 controls

RESULTS

Using the MESACUP anti-Skin profile TEST, both sensitivities and specificities for desmoglein 1, desmoglein 3, BP180, BP230, and type VII collagen autoantibodies were similar to those obtained using previous, specific ELISA systems and 88% of the results were concordant without any significant difference.

CONCLUSION

The MESACUP anti-Skin profile TEST had a similar performance to previously produced ELISA systems. The novel kit can be used for rapid diagnosis of most common autoimmune blistering diseases and is especially suitable for identifying overlapping disorders.

Immunofluorescence mapping in inherited epidermolysis bullosa: a study of 86 cases from India

BACKGROUND

Epidermolysis bullosa (EB) poses diagnostic challenges in infancy. In India, the diagnosis is largely clinical. There were no facilities to perform immunofluorescence mapping (IFM) until recently, and electron microscopy, which requires expertise to interpret, is limited to a few research laboratories.

OBJECTIVES

To describe the patterns of IFM staining in the various forms of EB in Indian patients and to correlate these findings with clinical diagnosis.

METHODS

We conducted a cross-sectional study of IFM findings in EB. Antibodies against type IV collagen, cytokeratin 14, laminin 332 and type VII collagen were used. Clinical correlation was performed in all cases, and concordance-discordance rates were calculated.

RESULTS

Eighty-six patients with a diagnosis of EB were included in the study. There were 29 with EB simplex (EBS), 18 with junctional EB (JEB) and 15 with dystrophic EB (DEB). The remaining 24 cases included rare variants, cases with overlapping clinical features and cases where the type of EB was not known. On IFM diagnosis, there were 32 cases of EBS, 15 JEB, 17 DEB and two Kindler syndrome. Two cases were not EB and 18 were inconclusive. IFM could establish the type in 12 of 15 cases (80%) that had overlapping clinical features. Most of these cases were under 1 year of age. Overall the concordance was 57% and was seen best in cases of EBS.

CONCLUSIONS

This is the first large study of IFM of the subtypes of EB in Indian patients. The study provides a framework for better understanding of EB in Indian patients and for better diagnosis and management, particularly in infancy.

Fcγ receptors III and IV mediate tissue destruction in a novel adult mouse model of bullous pemphigoid

Bullous pemphigoid (BP) and epidermolysis bullosa acquisita are subepidermal autoimmune blistering diseases mediated by autoantibodies against type XVII collagen (Col17) and Col7, respectively. For blister formation, Fc-mediated events, such as infiltration of inflammatory cells in the skin, complement activation, and release of proteases at the dermal-epidermal junction, are essential. Although in the neonatal passive transfer mouse model of BP, tissue destruction is mediated by Fcγ receptors (FcγRs) I and III, the passive transfer model of epidermolysis bullosa acquisita completely depends on FcγRIV. To clarify this discrepancy, we developed a novel experimental model for BP using adult mice. Lesion formation was Fc mediated because γ-chain-deficient mice and mice treated with anti-Col17 IgG, depleted from its sugar moiety at the Fc portion, were resistant to disease induction. By the use of various FcγR-deficient mouse strains, tissue destruction was shown to be mediated by FcγRIV, FcγRIII, and FcγRIIB, whereas FcγRI was not essential. Furthermore, anti-inflammatory mediators in already clinically diseased mice can be explored in the novel BP model, because the pharmacological inhibition of FcγRIV and depletion of granulocytes abolished skin blisters. Herein, we extended our knowledge about the importance of FcγRs in experimental BP and established a novel BP mouse model suitable to study disease development over a longer time period and explore novel treatment strategies in a quasi-therapeutic setting.

EndoS reduces the pathogenicity of anti-mCOL7 IgG through reduced binding of immune complexes to neutrophils

Endo-β-N-acetylglucosaminidase (EndoS) has been shown to act as a potent pathogen-derived immunomodulatory molecule in autoimmune diseases. Here we investigated how EndoS treatment reduces the pathogenicity of rabbit anti-mCOL7 IgG using different experimental models of epidermolysis bullosa acquisita (EBA). Our results show that the EndoS treatment does not interfere with the binding of the antibody to the antigen but reduces immune complex (IC)-mediated neutrophil activation by impairing the binding of the IC to FcγR on neutrophils. On the basis of this newly identified EndoS-mediated mechanism we hope to develop new strategies in the treatment of the disease.

A case of pemphigoid gestationis with concurrent IgG antibodies to BP180, BP230 and type VII collagen

A 22-year-old primigravida had a pruritic, erythematous, bullous eruption on the skin during the 26th week of gestation. After delivery the eruption flared up. The diagnosis of pemphigoid gestationis was confirmed based on histopathological and immunofluorescence findings. The result of immunoblotting showed IgG autoantibodies which reacted against BP230 in epidermal extracts and 290 kDa type VII collagen in dermal extracts. The BP180 antibodies were also detected by an enzyme-linked immunosorbent assay BP180NC16a diagnosis kit. Pulsed corticosteroid and cyclophosphamide resulted in a favourable response at the acute stage. The patient was cured in 2 years. The analysis of the patient's autoantibodies provides strong evidence for the involvement of epitope spreading in her autoimmune disease.

Induction of experimental epidermolysis bullosa acquisita by immunization with murine collagen VII

Epidermolysis bullosa acquisita (EBA) is an autoimmune subepidermal blistering disease caused by an autoreactive response against collagen VII, the major constituent of the anchoring fibrils at the epidermal basement membrane. The pathogenic relevance of collagen VII-specific autoantibodies has been conclusively demonstrated ex vivo and in experimental animals using antibody passive transfer models. To study the mechanisms of autoantibody production and tissue damage an animal model reproducing both the autoimmune response and the active skin disease is needed. In the present protocol, we describe the induction of an autoimmune response and active disease by immunizing mice with recombinant murine collagen VII and the analysis of the induced disease phenotype. The humoral and cellular immune response elicited in mice by immunization with the autoantigen, as well as the induced skin pathology replicate the features of the human disease at the clinical, histo- and immunopathological levels. Thus, this model is an excellent tool for investigating the mechanisms underlying pathogenic autoantibody production, the autoantibody-mediated tissue injury, and for the development of more effective therapeutic strategies in autoimmune diseases.

Epidermolysis bullosa acquisita: autoimmunity to anchoring fibril collagen

Epidermolysis bullosa acquisita (EBA) is a rare and acquired autoimmune subepidermal bullous disease of skin and mucosa. EBA includes various distinct clinical manifestations resembling genetic dystrophic epidermolysis bullosa (DEB), Bullous pemphigus, Brunsting-Perry pemphigoid, or cicatricial pemphigoid. These patients have autoantibodies against type VII collagen (C7), an integral component of anchoring fibrils (AFs), which are responsible for attaching the dermis to the epidermis. Destruction or perturbation of the normal functioning AFs clinically results in skin fragility, blisters, erosions, scars, milia, and nail loss, all features reminiscent of genetic dystrophic epidermolysis bullosa. These anti-C7 antibodies are "pathogenic" because when injected into a mouse, the mouse develops an EBA-like blistering disease. Currently, treatment is often unsatisfactory; however, some success has been achieved with colchicine, dapsone, photopheresis, plasmapheresis, infliximab, rituximab, and IVIG.

Epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is a rare, acquired, chronic subepidermal bullous disease of the skin and mucosa characterized by autoantibodies to type VII collagen (C7) structures, a major component of anchoring fibrils, which attach the epidermis to the dermis. EBA patients have tissue-bound and circulating antitype C7 autoantibodies that attack type C7 and result in a reduction or perturbation of normally functioning anchoring fibrils. Patients with EBA have skin fragility, blisters, erosions, scars, milia, and nail loss, all features reminiscent of genetic dystrophic epidermolysis bullosa. These immunoglobulin G antitype C7 antibodies are pathogenic, because when they are injected into mice, the mice develop an EBA-like blistering disease. In addition to the classical mechanobullous presentation, EBA also has several other distinct clinical syndromes similar to bullous pemphigoid, Brunsting-Perry pemphigoid, or cicatricial pemphigoid. Although treatment for EBA is often unsatisfactory, some therapeutic success has been achieved with colchicine, dapsone, plasmapheresis, photopheresis, infliximab, and intravenous immunoglobulin.

Autoimmunity against type VII collagen in inflammatory bowel disease

Autoimmunity against type VII collagen, an adhesion molecule of the extracellular matrix in epithelial basement membranes, is causing the rare organ-specific epidermolysis bullosa acquisita (EBA). An intriguing association between EBA and inflammatory bowel disease (IBD) has been extensively documented over the last decades, but, because of the very low incidence of EBA, received little attention from physicians involved in the care of patients with IBD. More recently, autoantibodies against type VII collagen have been detected in up to 68% of IBD patients. Although these findings suggest that chronic intestinal inflammation in IBD predisposes for autoimmunity against type VII collagen, their relevance for the pathogenesis of both IBD and EBA is still unclear. In this review article, the main features of the association between IBD and EBA are presented and pathomechanistic hypotheses as well as future lines of investigation in this area are discussed. Future research should provide new pathomechanistic insights and will likely facilitate the development of more specific and effective immunotherapeutic strategies for both conditions.

Bone marrow transplantation for recessive dystrophic epidermolysis bullosa

BACKGROUND

Recessive dystrophic epidermolysis bullosa is an incurable, often fatal mucocutaneous blistering disease caused by mutations in COL7A1, the gene encoding type VII collagen (C7). On the basis of preclinical data showing biochemical correction and prolonged survival in col7 −/− mice, we hypothesized that allogeneic marrow contains stem cells capable of ameliorating the manifestations of recessive dystrophic epidermolysis bullosa in humans.

METHODS

Between October 2007 and August 2009, we treated seven children who had recessive dystrophic epidermolysis bullosa with immunomyeloablative chemotherapy and allogeneic stem-cell transplantation. We assessed C7 expression by means of immunofluorescence staining and used transmission electron microscopy to visualize anchoring fibrils. We measured chimerism by means of competitive polymerase-chain-reaction assay, and documented blister formation and wound healing with the use of digital photography.

RESULTS

One patient died of cardiomyopathy before transplantation. Of the remaining six patients, one had severe regimen-related cutaneous toxicity, with all having improved wound healing and a reduction in blister formation between 30 and 130 days after transplantation. We observed increased C7 deposition at the dermal-epidermal junction in five of the six recipients, albeit without normalization of anchoring fibrils. Five recipients were alive 130 to 799 days after transplantation; one died at 183 days as a consequence of graft rejection and infection. The six recipients had substantial proportions of donor cells in the skin, and none had detectable anti-C7 antibodies.

CONCLUSIONS

Increased C7 deposition and a sustained presence of donor cells were found in the skin of children with recessive dystrophic epidermolysis bullosa after allogeneic bone marrow transplantation. Further studies are needed to assess the long-term risks and benefits of such therapy in patients with this disorder. (Funded by the National Institutes of Health; ClinicalTrials.gov number, NCT00478244.)

Cross-reactivity of autoantibodies from patients with epidermolysis bullosa acquisita with murine collagen VII

The pathomechanism of antibody-mediated tissue damage in autoimmune diseases can be best studied in experimental models by passively transferring specific autoantibodies into animals. The reproduction of the disease in animals depends on several factors, including the cross-reactivity of patient autoantibodies with the animal tissue. Here, we show that autoantibodies from patients with epidermolysis bullosa acquisita (EBA), a subepidermal autoimmune blistering disease, recognize multiple epitopes on murine collagen VII. Indirect immunofluorescence microscopy revealed that EBA patients' IgG cross-reacts with mouse skin. Overlapping, recombinant fragments of murine collagen VII were used to characterize the reactivity of EBA sera and to map the epitopes on the murine antigen by ELISA and immunoblotting. The patients' autoantibody binding to murine collagen VII triggered pathogenic events as demonstrated by a complement fixing and an ex vivo granulocyte-dependent dermal-epidermal separation assay. These findings should greatly facilitate the development of improved disease models and novel therapeutic strategies.

Injection of recombinant human type VII collagen corrects the disease phenotype in a murine model of dystrophic epidermolysis bullosa

Patients with recessive dystrophic epidermolysis bullosa (RDEB) have incurable skin fragility, blistering, and scarring due to mutations in the gene that encodes for type VII collagen (C7) that mediates dermal-epidermal adherence in human skin. We showed previously that intradermal injection of recombinant C7 into transplanted human DEB skin equivalents stably restored C7 expression at the basement membrane zone (BMZ) and reversed the RDEB disease features. In this study, we evaluated the feasibility of protein therapy in a C7 null mouse (Col7a1(-/-)) which recapitulates the features of human RDEB. We intradermally injected purified human C7 into DEB mice and found that the injected human C7 stably incorporated into the mouse BMZ, formed anchoring fibrils, and corrected the DEB murine phenotype, as demonstrated by decreased skin fragility, reduced new blister formation, and markedly prolonged survival. After 4 weeks, treated DEB mice developed circulating anti-human C7 antibodies. Most surprisingly, these anti-C7 antibodies neither bound directly to the mouse's BMZ nor prevented the incorporation of newly injected human C7 into the BMZ. Anti-C7 antibody production was prevented by treating the mice with an anti-CD40L monoclonal antibody, MR1. We conclude that protein therapy may be feasible for the treatment of human patients with RDEB.

Familial epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is an acquired blistering skin disorder caused by IgG autoantibodies directed against type VII collagen. In contrast to the genetic forms of epidermolysis bullosa, EBA is usually an acquired, sporadic disease. In this report, we describe a family with two cases of EBA in an uncle-nephew pair, and a third family member with asymptomatic circulating anti-type VII collagen antibodies. These findings provide support for the hypothesis that there is a genetic component to EBA.

The Alternative Pathway of Complement Activation Is Critical for Blister Induction in Experimental Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita is a subepidermal blistering disease associated with tissue-bound and circulating autoantibodies against type VII collagen, a major constituent of the dermal-epidermal junction. The passive transfer of Abs against type VII collagen into mice induces a subepidermal blistering disease dependent upon activation of terminal complement components. To further dissect the role of the different complement activation pathways in this model, we injected C1q-deficient, mannan-binding lectin-deficient, and factor B-deficient mice with rabbit Abs against murine type VII collagen. The development and evolution of blistering had a similar pattern in mannan-binding lectin-deficient and control mice and was initially only marginally less extensive in C1q-deficient mice compared with controls. Importantly, factor B-deficient mice developed a delayed and significantly less severe blistering disease compared with factor B-sufficient mice. A significantly lower neutrophilic infiltration was observed in factor B-deficient mice compared with controls and local reconstitution with granulocytes restored the blistering disease in factor B-deficient mice. Our study provides the first direct evidence for the involvement of the alternative pathway in an autoantibody-induced blistering disease and should facilitate the development of new therapeutic strategies for epidermolysis bullosa acquisita and related autoimmune diseases.

NADPH oxidase is required for neutrophil-dependent autoantibody-induced tissue damage

The contribution of phagocyte-derived reactive oxygen species to tissue injury in autoimmune inflammatory diseases is unclear. Here we report that granulocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase crucially contributes to tissue injury in experimental models of the antibody-mediated autoimmune disease epidermolysis bullosa acquisita. Neutrophil cytosolic factor 1-deficient mice lacking functional NADPH oxidase were resistant to skin blistering by the passive transfer of antibodies against type VII collagen. Pharmacological inhibition or deficiency of human NADPH oxidase abolished dermal-epidermal separation caused by autoantibodies and granulocytes ex vivo. In addition, recruitment of granulocytes into the skin was required for tissue injury, as demonstrated by the resistance to experimental blistering of wild-type mice depleted of neutrophils and of CD18-deficient mice. Transfer of neutrophil cytosolic factor 1-sufficient granulocytes into neutrophil cytosolic factor 1-deficient mice demonstrated that granulocytes provide the NADPH oxidase required for tissue damage. Our findings identify granulocyte-derived NADPH oxidase as a key molecular effector engaged by pathogenic autoantibodies and provide relevant targets for prevention of tissue damage in granulocyte-mediated autoimmune diseases.

Childhood epidermolysis bullosa acquisita with autoantibodies against the noncollagenous 1 and 2 domains of type VII collagen: case report and review of the literature

Epidermolysis bullosa acquisita (EBA) is an acquired subepidermal bullous disease characterized by IgG autoantibodies to type VII collagen, a major component of anchoring fibrils. Most patients with EBA are adult and develop autoantibodies to the noncollagenous (NC) 1 domain of type VII collagen. We describe a 4-year-old Japanese boy presenting pruritic vesicles and tense blisters over his whole body. Immunofluorescence studies revealed linear IgG/C3 deposits along the dermal-epidermal junction of the patient's skin, and circulating IgG autoantibodies mapping to the dermal side of 1 M NaCl-split skin. By immunoblotting analysis using dermal extracts as a substrate, the patient's IgG antibodies labelled a 290-kDa protein corresponding to type VII collagen. Immunoblotting studies using recombinant proteins demonstrated that the patient's circulating autoantibodies recognized not only the NC1 but also the NC2 domain of type VII procollagen. Review of the previously reported cases and the present case suggested that patients with EBA with autoantibodies to regions other than the NC1 domain are all children younger than 10 years of age with clinical features of an inflammatory phenotype.

Autoimmunity to type VII collagen in SKH1 mice is independent of regulatory T cells

Epidermolysis bullosa acquisita is an autoimmune blistering disease characterized by circulating and skin basement membrane-bound IgG autoantibodies to type VII collagen, a major structural protein of the dermal-epidermal junction. Regulatory T cells (T(reg)) suppress self antigen-mediated autoimmune responses. To investigate the role of T(reg) in the the autoimmune response to type VII collagen in a mouse model, a monoclonal antibody against mouse CD25 was used to deplete T(reg). A recombinant mouse type VII collagen NC1 domain protein and mouse albumin were used as antigens. SKH1 mice were used as a testing host. Group 1 mice received NC1 immunization and were functionally depleted of T(reg); group 2 mice received NC1 immunization and rat isotype control; and group 3 mice received albumin immunization and were functionally depleted of T(reg). Results demonstrated that anti-NC1 IgG autoantibodies with high titres, as determined by enzyme-linked immunosorbent assay and Western blotting, developed in all mice immunized with NC1 (groups 1 and 2), but were undetected in group 3 mice. The predominant subclasses of anti-NC1 autoantibodies were IgG1, IgG2a and IgG2b; furthermore, these antibodies carried only the kappa light chain. IgG autoantibodies in the sera of NC1-immunized mice reacted with mouse skin basement membrane in vitro and deposited in skin basement membrane in vivo as detected by indirect and direct immunofluorescence microscopy, respectively. Our data suggest that the development of autoimmunity against type VII collagen in mice is independent of T(reg) function and the autoimmune response is mediated by both Th1 and Th2 cells. We speculate that the basement membrane deposition of IgG may eventually lead to blister development.

Induction of Complement-Fixing Autoantibodies against Type VII Collagen Results in Subepidermal Blistering in Mice

Experimental models reproducing an autoimmune response resulting in skin blistering in immunocompetent animals are lacking. Epidermolysis bullosa acquisita (EBA) is a bullous skin disease caused by autoantibodies to type VII collagen. In this study, we describe an active disease model of EBA by immunizing mice of different strains with murine type VII collagen. All mice developed circulating IgG autoantibodies that recognized type VII collagen and bound to the lamina densa of the dermal-epidermal junction. Importantly, subepidermal blisters developed in 82% of SJL-1, 56% of BALB/c mice, and 45% of Fc gammaRIIb-deficient mice, but not in SKH-1 mice. In susceptible animals, deposits of IgG1, IgG2, and complement C3 were detected at the dermal-epidermal junction. In contrast, in the nondiseased mice, tissue-bound autoantibodies were predominantly of the IgG1 subclass and complement activation was weak or absent. This active disease model reproduces in mice the clinical, histopathological, and immunopathological findings in EBA patients. This robust experimental system should greatly facilitate further studies on the pathogenesis of EBA and the development of novel immunomodulatory therapies for this and other autoimmune diseases.

Induction of Epidermolysis Bullosa Acquisita in Mice by Passive Transfer of Autoantibodies from Patients

Epidermolysis bullosa acquisita (EBA) is an autoimmune sub-epidermal blistering disease characterized by autoantibodies to type VII (anchoring fibril) collagen. To date, however, direct evidence for a pathogenic role of human EBA autoantibodies has not been demonstrated. In this study, we affinity-purified anti-type VII collagen antibodies from EBA patients' sera and then injected them into adult hairless immunocompetent mice. Mice injected with EBA autoantibodies developed skin fragility, blisters, erosions, and nail loss on their paws - all features of EBA patients. By clinical, histological, immunological, and ultrastructural parameters, the induced lesions were reminiscent of human EBA. Histology showed bullous lesions with an epidermal-dermal separation. IgG and C3 deposits were observed at the epidermal-dermal junction. All mice had serum antibodies that labeled the dermal side of salt-split human skin like EBA sera. Direct immunogold electron microscopy specifically localized deposits of human IgG to anchoring fibrils. (Fab')(2) fragments generated from EBA autoantibodies did not induce disease. We conclude that EBA human patient autoantibodies cause sub-epidermal blisters and induce EBA skin lesions in mice. These passive transfer studies demonstrate that human EBA autoantibodies are pathogenic. This novel EBA mouse model can be used to further investigate EBA autoimmunity and to develop possible therapies.

IgG autoantibodies to type VII collagen and an exclusive IgG3 reactivity to the laminin alpha3 chain in a patient with an autoimmune subepidermal blistering disease

We describe a patient with widespread skin lesions and circulating IgG autoantibodies to both type VII collagen and laminin 5. Although autoantibodies to type VII collagen belonged to IgG2, IgG3, and IgG4 subclasses, laminin 5 was targeted exclusively by IgG3 autoantibodies. Interestingly, despite the presence of IgG3 autoantibodies, the patient's serum failed to fix complement to the dermoepidermal junction. In addition, these autoantibodies did not recruit and activate leukocytes or induce dermoepidermal separation in skin sectioned by cryostat. We report a most unusual case of an autoimmune subepidermal blistering with an exclusive IgG3 reactivity to laminin 5.

Induction of dermal-epidermal separation in mice by passive transfer of antibodies specific to type VII collagen

Epidermolysis bullosa acquisita (EBA) is a subepidermal blistering disorder associated with tissue-bound and circulating autoantibodies specific to type VII collagen, a major constituent of the dermal-epidermal junction. Previous attempts to transfer the disease by injection of patient autoantibodies into mice have been unsuccessful. To study the pathogenic relevance of antibodies specific to type VII collagen in vivo, we generated and characterized rabbit antibodies specific to a murine form of this antigen and passively transferred them into adult nude, BALB/c, and C57BL/6 mice. Immune rabbit IgG bound to the lamina densa of murine skin and immunoblotted type VII collagen. Mice injected with purified IgG specific to type VII collagen, in contrast to control mice, developed subepidermal skin blisters, reproducing the human disease at the clinical, histological, electron microscopical, and immunopathological levels. Titers of rabbit IgG in the serum of mice correlated with the extent of the disease. F(ab')(2) fragments of rabbit IgG specific to type VII collagen were not pathogenic. When injected into C5-deficient mice, antibodies specific to type VII collagen failed to induce the disease, whereas C5-sufficient mice were susceptible to blister induction. This animal model for EBA should facilitate further dissection of the pathogenesis of this disease and development of new therapeutic strategies.

Evidence that Anti-Type VII Collagen Antibodies Are Pathogenic and Responsible for the Clinical, Histological, and Immunological Features of Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disease characterized by autoantibodies to type VII (anchoring fibril) collagen. Therefore, it is a prototypic autoimmune disease defined by a well-known autoantigen and autoantibody. In this study, we injected hairless immune competent mice with purified immunoglobulin G (IgG) fraction of serum from rabbits immunized with the non-collagenous amino-terminal domain (NC1) of human type VII collagen, the domain known to contain immunodominant epitopes. As a control, identical mice were injected with the IgG fraction of serum from non-immunized rabbits. Mice injected with immune IgG developed subepidermal skin blisters and erosions, IgG deposits at the epidermal-dermal junction of their skin, and circulating anti-NC1 antibodies in their serum-all features reminiscent of patients with EBA. Similar concentrations of control IgG purified from normal rabbits did not induce disease in the mice. These findings strongly suggest that autoantibodies that recognize human type VII collagen in EBA are pathogenic. This murine model, with features similar to the clinical, histological, and immunological features of EBA, will be useful for the fine dissection of immunopathogenic mechanisms in EBA and for the development of new therapeutic interventions.

Type VII collagen is required for Ras-driven human epidermal tumorigenesis

Type VII collagen defects cause recessive dystrophic epidermolysis bullosa (RDEB), a blistering skin disorder often accompanied by epidermal cancers. To study the role of collagen VII in these cancers, we examined Ras-driven tumorigenesis in RDEB keratinocytes. Cells devoid of collagen VII did not form tumors in mice, whereas those retaining a specific collagen VII fragment (the amino-terminal noncollagenous domain NC1) were tumorigenic. Forced NC1 expression restored tumorigenicity to collagen VII-null epidermis in a non-cell-autonomous fashion. Fibronectin-like sequences within NC1 (FNC1) promoted tumor cell invasion in a laminin 5-dependent manner and were required for tumorigenesis. Tumor-stroma interactions mediated by collagen VII thus promote neoplasia, and retention of NC1 sequences in a subset of RDEB patients may contribute to their increased susceptibility to squamous cell carcinoma.

Granulocyte-derived elastase and gelatinase B are required for dermal-epidermal separation induced by autoantibodies from patients with epidermolysis bullosa acquisita and bullous pemphigoid

Epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP) are two clinically and immunologically distinct autoimmune subepidermal blistering skin diseases associated with IgG autoantibodies against the dermal-epidermal junction. BP antibodies are directed against the hemidesmosomal antigens BP180 and BP230, and those in patients with EBA target type VII collagen, a major component of anchoring fibrils. While the pathogenetic mechanisms of subepidermal blistering in BP have been previously studied using a passive transfer mouse model, the effector pathways of blister formation in EBA are largely unknown. Autoantibodies to type VII collagen and BP180 have recently been shown to induce leucocyte-mediated subepidermal cleavage in cryosections of human skin. The aim of the present study was to identify human leucocyte protease(s) instrumental in dermal-epidermal separation induced by autoantibodies to type VII collagen and BP180. When incubated with cryosections of human skin pretreated with IgG from patients with EBA or BP but not from patients with anti-laminin 5 mucous membrane pemphigoid or healthy controls, granulocytes were recruited to the dermal-epidermal junction and induced subepidermal splits. A combination of broad-range protease inhibitors as well as inhibitors of serine and matrix metalloproteases completely abolished dermal-epidermal separation induced by EBA or BP autoantibodies. When characterizing the proteases involved more specifically, selective inhibition of human leucocyte elastase or gelatinase B/MMP-9 was also found to result in suppression of blistering. These findings strongly suggest that elastase and gelatinase B are essential for granulocyte-mediated proteolysis resulting in dermal-epidermal separation in EBA and BP patients' skin.

A patient with both bullous pemphigoid and epidermolysis bullosa acquisita: an example of intermolecular epitope spreading

Bullous pemphigoid (BP) and epidermolysis bullosa acquisita are distinct autoimmune blistering disorders. BP is characterized by autoantibodies directed against the NC16A domain of collagen XVII, whereas patients with epidermolysis bullosa acquisita have autoantibodies against the NC1 domain of type VII collagen. We followed up a patient with BP for 9 years. During that time his clinical disease took on several features suggestive of epidermolysis bullosa acquisita. The objective of this study was to determine if the patient's autoantibody profile reflected the change in his clinical picture. Enzyme-linked immunosorbent assay and immunoblotting for detection and subclass determination of autoantibodies to type XVII and type VII collagen were performed on banked patient sera from the 9-year period. The patient's initial autoantibodies were exclusively IgG1 directed against collagen XVII. During the course of his illness, the subclass specificity of the patient's type XVII collagen autoantibodies shifted to the IgG4 subclass and during the same time interval the patient developed IgG2 autoantibodies directed against type VII collagen. This patient with BP exhibited both subclass shifting and development of a second autoantibody system that correlated with a change in the clinical appearance of the disease. The analysis of the patient's autoantibodies provides strong evidence for the involvement of epitope spreading in the evolution of his autoimmune disease.

Epidermolysis bullosa acquisita sera react with distinct epitopes on the NC1 and NC2 domains of type VII collagen: study using immunoblotting of domain-specific recombinant proteins and postembedding immunoelectron microscopy

BACKGROUND

The sera of epidermolysis bullosa acquisita (EBA) react with type VII collagen, a major component of anchoring fibrils, in which the major epitopes have been considered to be present in the N-terminal noncollagenous (NC) 1 domain.

OBJECTIVES

To determine whether there are also epitopes in the C-terminal NC2 domain, and to determine their ultrastructural localization.

METHODS

Immunoblotting using recombinant proteins of the NC1 and NC2 domains of type VII collagen, and postembedding immunoelectron microscopy.

RESULTS

Twenty of 28 EBA sera tested reacted with the NC1 domain and eight sera reacted with the NC2 domain. The sera that reacted with the NC1 domain showed immunoreactivity within the lamina densa and the sera that reacted with the NC2 domain showed immunoreactivity in the dermis 300-360 nm below the lamina densa.

CONCLUSIONS

This study clearly identified the presence of epitopes in the NC2 domain, and showed that the epitope in the NC1 domain is present in the lamina densa and that the epitope in the NC2 domain is in the dermis below the lamina densa.

The lupus band: do the autoantibodies target collagen VII?

BACKGROUND

Circulating autoantibodies directed against basement membrane zone (BMZ) components from patients with bullous pemphigoid and epidermolysis bullosa acquisita have been used to identify their target antigen in the skin and to confirm pathogenicity. Although the pattern of immunofluorescence in those diseases is similar to the lupus band, little is known about the origin and pathogenesis of the lupus band. Identifying the binding sites of the lupus band could provide a clue to the nature of the autoantigen that stimulates autoantibody formation in the skin of patients with systemic lupus erythematosus (SLE) and might provide valuable insight into the factors that influence the localization and pathogenicity of the lupus band.

OBJECTIVES

To investigate the relation between the lupus band and the main BMZ components and to identify the target epitopes of autoantibodies deposited in the skin of patients with SLE.

METHODS

Colocalization of the main components of the skin BMZ in nonlesional SLE skin with the lupus band was investigated using conventional immunofluorescence and confocal laser scanning microscopy. The effect of collagenase and pepsin on the expression of the lupus band was correlated with the differential sensitivity of these proteases on the collagenous and noncollagenous (NC) domains of collagen VII. Reactivity of sera from patients with SLE to a complete recombinant human NC1 domain of type VII collagen was then investigated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Near complete colocalization of the lupus band with collagen VII was found in this study, and chemical degradation of the skin attenuated the expression of the lupus band. Collectively, the NC1 domain of collagen VII was suggested as the target antigen of the lupus band, but none of the sera from patients with SLE reacted with recombinant NC1 domain-coated ELISA plates. Alternative explanations for the results of the colocalization of the lupus band with collagen VII are discussed.

CONCLUSIONS

The lupus band colocalized with collagen type VII. The findings of this study ruled out the NC1 domain of collagen VII as a target antigen for circulating autoantibodies in SLE patients with no clinical evidence of blistering. Further studies are required to determine if other regions of collagen VII or another BMZ component is the target antigen for the immunoglobulins of the lupus band.

A case of nonscarring subepidermal blistering disease associated with autoantibodies reactive with both type VII collagen and laminin 5

A 35-year-old Japanese woman had recurrent, pruritic, vesicular lesions on the face, neck and upper back as well as erosive lesions of the oral cavity and genitalia. The skin and mucosal lesions healed without scarring upon the systemic administration of corticosteroid and azathioprine. Direct immunofluorescence revealed linear deposits of IgG, IgA and C3 at the cutaneous basement membrane zone. Indirect immunofluorescence on 1 M NaCl-split human skin sections demonstrated that the patient's IgG antibodies reacted with the dermal side of the split, while IgA antibodies weakly reacted with the epidermal side. By immunoblot analyses, the patient's serum reacted with the NC1 domain of type VII collagen as well as both the alpha3- and beta3-subunits of laminin 5. We regarded our case as a nonscarring subepidermal blistering disease with autoantibodies to both type VII collagen and two different subunits of laminin 5. Such a case has not been previously reported.

Immunofluorescence studies using skin sections of recessive dystrophic epidermolysis bullosa patients indicated that the antigen of anti-p200 pemphigoid is not a fragment of type VII collagen

BACKGROUND

There are a large number of autoimmune bullous diseases, which have distinct autoantibodies. Several reports on cases with IgG autoantibodies against a novel 200 kDa dermal protein have been published, for which we suggested the term, anti-p200 pemphigoid. However, the nature of this 200 kDa antigen has not been well characterized.

OBJECTIVE

In this study, we examined the relationship between the 200 kDa protein and type VII collagen.

METHODS

We collected sera from 12 cases of anti-p200 pemphigoid and skin sections from six cases of recessive dystrophic epidermolysis bullosa (RDEB). The reactivity of these sera was examined by indirect immunofluorescence using sections of the disease skin.

RESULTS

we have shown that all the 12 anti-p200 pemphigoid sera could react with basement membrane zone of five cases of RDEB, while epidermolysis bullosa acquisita (EBA) sera were negative in these skins. In addition, in a case of RDEB, EBA sera reacted with intracytoplasmic deposition of type VII collagen, while no anti-p200 pemphigoid sera showed this reactivity.

CONCLUSION

These results strongly suggested that the 200 kDa antigen is not a fragment of type VII collagen, but a specific autoantigen.

Immunomapping of EBA sera to multiple epitopes on collagen VII: further evidence that anchoring fibrils originate and terminate in the lamina densa

Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disease with circulating antibodies to type VII collagen, a major component of anchoring fibrils located at the dermal-epidermal junction. The purpose of this study was to further confirm the ultrastructural organisation of anchoring fibrils and to assess the relationship between the clinical phenotype of EBA and target site of their autoantibodies on anchoring fibrils. We studied the ultrastructural binding site of circulating autoantibodies from two patients with atypical clinical features who predominantly presented with oral lesions, and compared this with two patients with clinically typical forms of EBA. Immunoblotting of whole dermal extracts showed labelling of 290-kDa bands consistent with that of type VII collagen as well as the non-collagenous (NC-1) domain fusion protein in three out of four patients' sera. Postembedding immunoelectron microscopy (IEM) using Lowicryl K11M embedded normal human skin and patients' sera demonstrated the majority of labelling within the lamina densa, not below the lamina densa. We conclude that EBA autoantibodies in these patient's sera bind to the NC-1 domain of collagen VII situated in the lamina densa of the epidermal basement membrane, regardless of the EBA clinical phenotype. This confirms the previous notion that anchoring fibrils originate and terminate in the lamina densa.

Anti-epiligrin cicatricial pemphigoid and epidermolysis bullosa acquisita: differentiation by use of indirect immunofluorescence microscopy

Binding of autoantibodies to laminin 5 and type VII collagen causes anti-epiligrin cicatricial pemphigoid and epidermolysis bullosa acquisita, respectively. Differentiation between these two dermal-binding autoimmune bullous dermatoses is not yet possible by indirect immunofluorescence microscopy. In this study we tested whether two recently described immunofluorescence techniques, "knockout" skin substrate and fluorescent overlay antigen mapping, can differentiate between anti-epiligrin cicatricial pemphigoid and epidermolysis bullosa acquisita. A total of 10 sera were tested: 4 with antilaminin 5, and 6 with antitype VII collagen autoantibodies, as characterized by either immunoblot or immunoprecipitation analysis. Differentiation between anti-epiligrin cicatricial pemphigoid and epidermolysis bullosa acquisita was possible in all 10 sera by indirect immunofluorescence using either knockout skin substrate or fluorescent overlay antigen mapping technique.

Vesiculobullous systemic lupus erythematosus: a case with circulating IgG and IgA autoantibodies to type VII collagen

We report a case of a 17-year-old Japanese boy with vesiculobullous systemic lupus erythematosus. He had a facial "butterfly" erythema and blistering eruption develop. Antinuclear, RNP, and Sm antibodies were positive. The American Rheumatism Association criteria for a diagnosis of systemic lupus erythematosus were met. A skin biopsy specimen showed papillary microabscesses of neutrophils and subepidermal blisters and deposits of IgG, IgA, IgM, and C3 by direct immunofluorescence. Indirect immunofluorescence on salt-split skin showed linear IgG, IgA, and C3 deposits on the dermal side. IgG and IgA autoantibodies in his serum reacted with the 290-kd proteins of type VII collagen from human dermal extracts and the recombinant fusion proteins from the noncollagenous domain of type VII collagen by Western immunoblot. To our knowledge, this is the first report of vesiculobullous systemic lupus erythematosus with circulating IgG and IgA autoantibodies to type VII collagen.

Childhood epidermolysis bullosa acquisita: a novel variant with reactivity to all three structural domains of type VII collagen

Most patients with epidermolysis bullosa acquisita develop an autoimmune response to the non-collagenous (NC) 1 domain of type VII collagen. We report a 4-year-old girl of white European descent presenting with widespread blistering disease involving the face, hands, genital area and oral mucosa. Histopathology revealed subepidermal blisters, and linear deposits of IgG and C3 were seen along the dermal-epidermal junction on direct immunofluorescence (IF) microscopy of a perilesional skin biopsy. On indirect IF microscopy, circulating autoantibodies exclusively stained the dermal side of 1 mol L-1 NaCl-split skin. The patient's IgG autoantibodies labelled a 290-kDa protein on Western blotting of dermal extracts, and reacted with the NC1, NC2 and triple helical domains of type VII collagen on immunoblotting of recombinant and cell-derived fragments obtained by pepsin and collagenase digestion of the full-length protein. Oral methylprednisolone and dapsone led to clearance of lesions, which healed with mild scarring and milia formation. Treatment was discontinued after 1 year and the patient has now been in remission for more than 3 years.

Autoantibodies to type VII collagen mediate Fcgamma-dependent neutrophil activation and induce dermal-epidermal separation in cryosections of human skin

Epidermolysis bullosa acquisita is an autoimmune subepidermal blistering disease associated with autoantibodies to type VII collagen, the major constituent of anchoring fibrils. Previous attempts to demonstrate the blister-inducing potential of autoantibodies to this protein have failed. To address this question, we used an in vitro model involving cryosections of human skin incubated with patients' autoantibodies and leukocytes from healthy donors. We show that sera from 14 of 16 epidermolysis bullosa acquisita patients, in contrast to sera from healthy controls, induced dermal-epidermal separation in the cryosections. Recruitment and activation of neutrophils at the dermal-epidermal junction was necessary for split induction, whereas mononuclear cells were not required. Importantly, patients' autoantibodies affinity-purified against a recombinant form of the noncollagenous 1 domain of type VII collagen retained their blister-inducing capacity in a dose-dependent manner, whereas patients' IgG that was depleted of reactivity to type VII collagen lost this ability. Monoclonal antibody LH7.2 to the noncollagenous 1 domain of type VII collagen also induced subepidermal splits in the cryosections; F(ab')(2) fragments of autoantibodies to type VII collagen were not pathogenic. We demonstrate the capacity of autoantibodies to type VII collagen to trigger an Fcgamma-dependent inflammation leading to split formation in cryosections of human skin.