Linear IgA disease: the IgA and IgG response to the epidermal antigens demonstrates that intermolecular epitope spreading is associated with IgA rather than IgG antibodies, and is more common in adults

Anti-NC16A IgA from Patients with Linear IgA Bullous Dermatosis Induce Neutrophil-Dependent Subepidermal Blistering in Mice

Linear IgA bullous dermatosis (LABD) is an acquired autoimmune subepidermal blistering skin disease characterized by circulating and tissue-bound IgA autoantibodies that recognize epitopes within the hemidesmosomal protein BP180, including its NC16A domain. Histologically, LABD has long been defined by neutrophil infiltration and dermal-epidermal separation. However, the pathogenic roles of anti-NC16A IgA and neutrophils in LABD, as well as their interactions, have not been thoroughly studied. We show that passive transfer of patient-derived anti-NC16A IgA induce clinical and histologic LABD pathology in humanized NC16A mice that are reconstituted locally or systemically with human neutrophils. The lesional skin of mice exhibits significantly elevated levels of the neutrophil chemoattractants CXCL-1 and CXCL-2. Furthermore, we show significantly increased levels of the neutrophil chemoattractant IL-8 in blister fluids of patients with LABD. This study provides direct evidence that anti-NC16A IgA in patients with LABD are pathogenic and interact with neutrophils to mediate tissue injury and subepidermal blister formation. This study further corroborates the importance of neutrophil-mediated tissue injury in LABD disease physiology and establishes a clinically relevant in vivo model system that can be used to systematically dissect the immunopathogenesis of LABD.

Neonatal Autoimmune Subepidermal IgG/IgA Blistering Disease With Severe Laryngeal and Esophageal Involvement: A Report of a Case and Review of the Literature

Neonatal autoimmune subepidermal blistering disease is rare. Mucosal involvement is more common in neonatal linear immunoglobulin A (IgA) bullous dermatosis. We describe a neonate with subepidermal cutaneous blistering disease with severe laryngeal and esophageal involvement leading to acute respiratory distress. Histopathology demonstrated a subepidermal blister with neutrophils and eosinophils at the dermal base. Collagen IV was detected at the dermal floor, and direct immunofluorescence showed linear IgG, IgA, and C3 deposits at the basement membrane zone. The patient demonstrated markedly increased serum levels of anti-BP180 NC16A and anti-BP230 IgG antibodies (Abs) but failed to show anti-LAD-1 IgA Abs. His healthy mother showed serum anti-LAD-1 IgA Abs but did not show anti-BP180 and anti-BP230 Abs. The neonate responded promptly to systemic corticosteroid therapy. A review of the literature detected 11 cases of neonatal subepidermal blistering disease with linear IgA deposits. Nine of these cases demonstrated coexisting linear IgG deposits, often with C3. Respiratory compromise was present in most of the cases. Neutrophils and eosinophils were commonly present in the inflammatory cell infiltrates. Besides our case, 2 cases of neonatal IgG/IgA subepidermal blistering disease with esophageal involvement were previously described. IgA Abs were present in the sera of both cases. Anti-LAD-1 IgA Abs were detected in the mother's serum of our case alone, but IgA Abs do not cross the placenta. Our case was consistent with neonatal IgG/IgA pemphigoid. Neonatal IgG/IgA subepidermal blistering disease may be associated with severe laryngeal and esophageal involvement leading to respiratory compromise. Expedited diagnosis and prompt treatment are warranted.

Linear IgA bullous dermatosis

Aim: to present a clinical case of linear IgA bullous dermatosis.Materials and methods. A 44 years old patient complaining of skin rashes on the trunk and extremities, accompanied by severe itching was examined. We carried out a morphological investigation of biopsy samples derived from the lesion and apparently unaffected skin areas using the method of indirect immunofluorescence.Results. The patient having rashes in the form of multiple vesicles and small bubbles with a tight cover, which had been grouped into figures resembling pearl necklaces, demonstrated the presence of focal subepidermal cracks (subepidermal bubble in one location), as well as a linear deposition of IgA along the epidermal basement membrane. According to the clinical picture and following the histological and immunofluorescent investigation of skin biopsies, the patient was diagnosed with linear IgA bullous dermatosis. Lesion regression was achieved as a result of systemic therapy with prednisolone at a dose of 50 mg per day.Conclusion. The diagnosis of linear IgA bullous dermatosis should be made on the basis of skin biopsy investigation by the method of indirect immunofluorescence. Systemic glucocorticosteroids are seen as an effective approach to the treatment of such patients.

Antigen recognition in the pathogenesis of immunoglobulin A-related autoimmune bullous diseases

Immunoglobulin A (IgA) is the most common subtype of antibodies in mucosal surfaces. In most of autoimmune bullous diseases, however, immunoglobulin G (IgG) is the main pathogenic antibody that plays a role through complementation. The IgA antibody for epidermal connection protein can be found in the sera of some patients with blistering skin disease. Of these patients, some have the IgA antibody in their sera, while others have IgG and IgA antibodies. IgA-related autoimmune bullous diseases are less common in clinical practice. In the past, these diseases were not fully understood and their classifications were confusing. Recently, some progress has been made in the study of these diseases.

Humoral Epitope Spreading in Autoimmune Bullous Diseases

Autoimmune blistering diseases are characterized by autoantibodies against structural adhesion proteins of the skin and mucous membranes. Extensive characterization of their autoantibody targets has improved understanding of pathogenesis and laid the basis for the study of antigens/epitopes diversification, a process termed epitope spreading (ES). In this review, we have reported and discussed ES phenomena in autoimmune bullous diseases and underlined their functional role in disease pathogenesis. A functional ES has been proposed: (1) in bullous pemphigoid patients and correlates with the initial phase of the disease, (2) in pemphigus vulgaris patients with mucosal involvement during the clinical transition to a mucocutaneous form, (3) in endemic pemphigus foliaceus, underlining its role in disease pathogenesis, and (4) in numerous cases of disease transition associated with an intermolecular diversification of immune response. All these findings could give useful information to better understand autoimmune disease pathogenesis and to design antigen/epitope specific therapeutic approaches.

Idiopathic linear IgA bullous dermatosis: prognostic factors based on a case series of 72 adults

BACKGROUND

Linear IgA bullous dermatosis (LABD) is a clinically and immunologically heterogeneous, subepidermal, autoimmune bullous disease (AIBD), for which the long-term evolution is poorly described.

OBJECTIVES

To investigate the clinical and immunological characteristics, follow-up and prognostic factors of adult idiopathic LABD.

METHODS

This retrospective study, conducted in our AIBD referral centre, included adults, diagnosed between 1995 and 2012, with idiopathic LABD, defined as pure or predominant IgA deposits by direct immunofluorescence. Clinical, histological and immunological findings were collected from charts. Standard histology was systematically reviewed, and indirect immunofluorescence (IIF) on salt-split skin (SSS) and immunoblots (IBs) on amniotic membrane extracts using anti-IgA secondary antibodies were performed, when biopsies and sera obtained at diagnosis were available. Prognostic factors for complete remission (CR) were identified using univariate and multivariate analyses.

RESULTS

Of the 72 patients included (median age 54 years), 60% had mucous membrane (MM) involvement. IgA IIF on SSS was positive for 21 of 35 patients tested; 15 had epidermal and dermal labellings. Immunoelectron microscopy performed on the biopsies of 31 patients labelled lamina lucida (LL) (26%), lamina densa (23%), anchoring-fibril zone (AFz) (19%) and LL+AFz (23%). Of the 34 IgA IBs, 22 were positive, mostly for LAD-1/LABD97 (44%) and full-length BP180 (33%). The median follow-up was 39 months. Overall, 24 patients (36%) achieved sustained CR, 19 (29%) relapsed and 35% had chronic disease. CR was significantly associated with age > 70 years or no MM involvement. No prognostic immunological factor was identified.

CONCLUSIONS

Patients with LABD who are < 70 years old and have MM involvement are at risk for chronic evolution.

Drug-Induced Linear IgA Bullous Dermatosis

We report the case of a 69-year-old Japanese woman with multiple blistering lesions covering almost her whole body. Linear IgA and C3 depositions were seen at the basement membrane zone on direct immunofluorescence (IF). Linear IgA bullous dermatosis (LABD) is one of the autoimmune diseases resulting in subepidermal blisters. It is clinically similar to bullous pemphigoid and IF is required to distinguish the two diseases. In this case, the blistering lesions appeared after vancomycin treatment. This drug was strongly suspected as a cause of LABD in light of the clinical course of the patient even though a drug-lymphocyte stimulating test was negative. Among the various implicated causative drugs, vancomycin is the most commonly associated with LABD.

Linear IgA disease: clinical presentation, diagnosis, and pathogenesis

Linear IgA disease is one of the rarer subepidermal blistering diseases. Linear IgA disease is a chronic, acquired, autoimmune blistering disease that is characterized by subepidermal blistering and linear deposition of IgA basement membrane antibodies. The disease affects both children and adults and, although there are some differences in their clinical presentations, there is considerable overlap with shared immunopathology and immunogenetics.

Linear immunoglobulin A bullous dermatosis

Linear immunoglobulin A (IgA) bullous dermatosis, also known as linear IgA disease, is an autoimmune mucocutaneous disorder characterized by subepithelial bullae, with IgA autoantibodies directed against several different antigens in the basement membrane zone. Its immunopathologic characteristic resides in the presence of a continuous linear IgA deposit along the basement membrane zone, which is clearly visible on direct immunofluorescence. This disorder shows different clinical features and distribution when adult-onset of linear IgA disease is compared with childhood-onset. Diagnosis is achieved via clinical, histopathologic, and immunopathologic examinations. Two common therapies are dapsone and sulfapyridine, which reduce the inflammatory response and achieve disease remission in a variable period of time.

Linear IgA disease: clinical presentation, diagnosis, and pathogenesis

Linear IgA disease is one of the rarer subepidermal blistering diseases. Linear IgA disease is a chronic, acquired, autoimmune blistering disease that is characterized by subepidermal blistering and linear deposition of IgA basement membrane antibodies. The disease affects both children and adults and, although there are some differences in their clinical presentations, there is considerable overlap with shared immunopathology and immunogenetics.

Role of BP180NC16a-enzyme-linked immunosorbent assay (ELISA) in the diagnosis of bullous pemphigoid in China

BACKGROUND

Autoantibodies of bullous pemphigoid (BP) patients react with two components of the hemidesmosome of stratified epithelia: the BP antigen 230 (BP230) and the BP antigen 180 (BP180). Recently, strong evidence has been provided that autoantibodies to BP180 play a key role in subepidermal blister formation in BP patients, and NC16A contains an important antigen determinant of BP.

OBJECTIVE

To study the role of BP180NC16a enzyme-linked immunosorbent assay (BP180NC16a-ELISA) in the diagnosis of BP in China.

METHODS

Sera from BP patients (n = 42) and control subjects (normal controls, n = 24; pemphigus patients, n = 18) were measured by BP180NC16a-ELISA. All BP sera were obtained at presentation from patients who had not received previous systemic treatment. The values of immunoglobulin G (IgG) antibody levels measured by ELISA were compared with those measured by indirect immunofluorescence (IIF) (gold standard for the diagnosis of BP) on salt-split skin.

RESULTS

Using BP180NC16a-ELISA, 41 of the 42 BP sera were positive, whereas only one of the serum samples from 24 normal controls was positive and all the pemphigus sera showed a negative result. Thus, the sensitivity and specificity of BP180NC16a-ELISA were both 97.62%. There was no correlation between the mean ELISA values and IIF titers. The ELISA and IIF results were further compared and analyzed using a 2 x 2 contingency table, which showed that they were not significantly different.

CONCLUSIONS

It is suggested that BP180NC16a-ELISA is a useful tool for the diagnosis of BP.

Childhood linear IgA bullous disease triggered by amoxicillin-clavulanic acid

Linear immunoglobulin A bullous disease is an autoimmune subepidermal blistering disease that has been described in both children and adults. Reports have shown that as many as two-thirds of occurrences may be drug-induced. The offending drugs include antibiotics, predominantly vancomycin, nonsteroidal anti-inflammatory agents and diuretics. We report childhood linear immunoglobulin A bullous dermatosis developing following amoxicillin-clavulanic acid administration. The patient presented with characteristic blisters in an annular fashion, likened to a ''crown of jewels.'' The diagnosis was confirmed by the presence of a linear band of immunoglobulin A at the dermoepidermal junction on direct immunofluorescence. The lesions resolved with withdrawal of the drug, and systemic therapy was not required. We review the current literature and concepts of drug-induced linear immunoglobulin A bullous disease.

Coexistence of psoriasis and linear IgA disease in a patient with recent herpes zoster infection

We report the case of a 29-year-old man with chronic plaque psoriasis who developed linear IgA disease following herpes zoster infection. There has only been one previous report describing the coexistence of psoriasis and linear IgA disease, which was confirmed by immunopathological studies. In our patient, immunoblotting studies identified IgA antibodies binding to BP180 and BP230 antigens, and IgG autoantibodies binding weakly to the BP180 antigen. This is an interesting case that we believe is an example of epitope spreading in the development of autoimmune subepidermal bullous diseases.

Avancées moléculaires dans la physiopathologie des maladies bulleuses autoimmunes

Autoimmune blistering skin diseases are characterized by the production of autoantibodies directed against adhesive structures of the skin. These organ specific autoimmune diseases included pemphigus in which autoantibodies target proteins of the desmosomal complex, and subepidermal autoimmune diseases characterized by autoantibodies directed against structural proteins of the dermoepidermal junction. Binding of autoantibodies to their targets induces a loss of adhesion between keratinocytes in pemphigus and alterations of the dermoepidermal junction in subepidermal autoimmune diseases. Progresses during the last twenty years had allowed the identification of target autoantigens and the characterization of their adhesive functions, a better understanding of the pathogenesis of these diseases and the development of new diagnostic tools.

Linear IgA disease: the IgA and IgG response to dermal antigens demonstrates a chiefly IgA response to LAD285 and a dermal 180-kDa protein

BACKGROUND

Linear IgA disease (LAD) of adults and children is mediated by IgA antibodies that target proteins of the epithelial adhesion complex. Most studies have concentrated on the epidermal-associated antigens; the dermal antigens remain unresolved.

OBJECTIVES

To determine the dermal antigen repertoire of IgA and IgG antibodies in LAD.

METHODS

Immunoblotting was carried out on salt-split and urea-extracted dermal skin extracts with IgA antibodies (63 adult and 34 childhood sera) and with IgG antibodies (49 adult and 18 childhood sera).

RESULTS

Antigens were identified by IgA (61%), IgG (27%) and by both antibody isotypes (19%). LAD285 and an antigen of 180 kDa were the major dermal antigens identified, and antigens of 230 kDa, collagen VII and a protein under 100 kDa were identified less commonly. IgA autoantibodies from adults bound single antigens more frequently than multiple antigens; from children they bound single and multiple antigens equally. The binding of multiple antigens was, however, more common in children than adults. The IgG response was weaker. The 180-kDa antigen was the main IgG dermal target, and with a single exception, IgG autoantibodies targeted single antigens.

CONCLUSIONS

There was an IgA and IgG response to dermal antigens in LAD; however, the dual antibody response was limited. The antibody response to LAD285 and a 180-kDa antigen (probably BP180) suggests that intermolecular epitope spreading of the antigens associated with the extracellular matrix/dermal components of the basement membrane contributes to the immunopathology of the disease. The restricted IgG response suggests that dermal-binding IgG autoantibodies are not pathologically significant.