IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis

Please cite this paper as: IgA autoantibodies in the pemphigoids and linear IgA bullous dermatosis. Experimental Dermatology 2010; 19: 648–653. Background: Patients with bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and pemphigoid gestationis (PG) have IgG antibodies against BP180 and BP230, components of the hemidesmosomes. Patients with linear IgA bullous dermatosis (LABD) have IgA autoantibodies against a 97/120‐kDa protein which is highly homologous to a shedded fragment of the BP180‐ectodomain. Objectives: The aim of our study was to determine the incidence of IgA autoantibodies directed against BP180/BP230 in the pemphigoids and LABD and to determine the antigenic regions that are targeted by IgA autoantibodies. Methods: Utilizing baculovirus‐expressed recombinant BP180 and BP230 proteins, we performed immunoblot analyses for IgA reactivity of sera from patients with BP (n = 30), MMP (n = 10), PG (n = 6), LABD (n = 6) and from control patients with non‐related pruritic dermatoses (n = 8). Results: IgA reactivity against BP180 and/or BP230 was detected in 19/30 of the BP, in 7/10 of the MMP, in 6/6 of the LABD and in 3/6 of the PG sera, respectively, but not in the control group. In all subgroups, the major antigenic site recognized by IgA antibodies was located within the NH₂‐terminus of the BP180‐ectodomain, but only a minority of the sera showed also IgA reactivity against the BP180‐NC16a‐domain. IgA reactivity against the central domain of BP180 was more frequently seen than against its COOH‐terminus. IgA against the COOH‐ and NH₂‐terminus of BP230, respectively, was detected in 6/30 of the BP, 1/10 of the MMP, 1/6 of the LABD and 0/8 control sera. Conclusion: IgA reactivity against BP180 and/or BP230 is a common finding in the pemphigoids.     

Mucous membrane pemphigoid with immunoglobulin G autoantibodies against full-length and 120-kDa ectodomain of BP180

Mucous membrane pemphigoid (MMP) is a rare autoimmune, subepidermal, bullous disease characterized by erosive lesions on the mucous membranes and skin. MMP reacts with various target antigens including BP180, laminin-332, β4 integrin, α6 integrin or type VII collagen. We present a 67-year-old male MMP patient who had lesions on the oral and ocular mucous membranes and facial skin. By immunoblot analyses, immunoglobulin G autoantibodies in the patient's sera reacted with full-length BP180 and the 120-kDa ectodomain of BP180 (LAD-1).     

A case of bullous pemphigoid successfully treated by plasmapheresis: assessment of the change in titers of circulating antibodies by immunoblotting and enzyme-linked immunosorbent assay

We report a case of bullous pemphigoid successfully treated with double filtration plasmapheresis. The changes in titers of circulating autoantibodies were assessed by immunoblotting and enzyme-linked immunosorbent assay (ELISA) using a recombinant protein of the non-collagenous 16a (NC16a) domain of the 180 kDa bullous pemphigoid antigen (BP180). The ELISA was shown to be more sensitive in detecting disease-specific antoantibodies in the bullous pemphigoid sera. The reduction of titers of circulating autoantibodies in the sera correlated well with the decrease in the disease activity in both the first and second rounds of plasmapheresis treatment in this case.     

Mapping of epitopes on the BP180 ectodomain targeted by IgA and IgG autoantibodies in patients with the lamina lucida-type of linear IgA disease

Abstract Linear IgA disease (LAD) is an autoimmune subepidermal blistering skin disease characterized by the linear deposition of IgA at the dermoepidermal junction. Serum from patients with LAD most commonly contains autoantibodies that are directed against the hemidesmosomal transmembrane glycoprotein BP180 (type XVII collagen). Various antigenic sites on the extracellular domain of this anchoring filament protein have been shown to be targeted by autoantibodies in different autoimmune bullous skin diseases, including bullous pemphigoid and cicatricial pemphigoid (CP). However, little is known about epitopes on BP180 recognized by autoantibodies in LAD. In this study, we used three recombinant GST fusion proteins, together roughly covering the entire BP180 ectodomain, to characterize the autoimmune response in serum from patients with LAD. Interestingly, we found both IgA and IgG reactivity to all three portions of the BP180 ectodomain. The strongest reactivity was observed with the C-terminal portion of BP180. This is also the major region recognized by autoantibodies in patients with CP. This finding correlates with the observation that there may be significant overlap of the clinical and immunopathological findings in LAD and CP. Received: 21 August 2000 / Revised: 8 November 2000 / Accepted: 13 December 2000     

Japanese guidelines for the management of pemphigoid (including epidermolysis bullosa acquisita)

The pemphigoid group is a category of autoimmune subepidermal blistering diseases in which autoantibodies deposit linearly at the epidermal basement membrane zone (BMZ). The main subtypes of pemphigoid mediated by immunoglobulin G autoantibodies are bullous pemphigoid (BP), mucous membrane pemphigoid (MMP) and epidermolysis bullosa acquisita (EBA). To establish the first guidelines approved by the Japanese Dermatological Association for the management of pemphigoid diseases, the Committee for Guidelines for the Management of Pemphigoid Diseases (Including EBA) was founded as part of the Study Group for Rare Intractable Skin Diseases under the Ministry of Health, Labor and Welfare Research Project on Overcoming Intractable Diseases. These guidelines aim to provide current information for the management of BP, MMP and EBA in Japan. Based on evidence, the guidelines summarize the clinical and immunological manifestations, pathophysiologies, diagnostic criteria, disease severity determination criteria, treatment algorithms and treatment recommendations. Because of the rarity of these diseases, there are few clinical studies with a high degree of evidence, so several parts of these guidelines were established based on the opinions of the Committee. To further optimize these guidelines, periodic revision in line with the new evidence is necessary.     

The 120-kDa soluble ectodomain of type XVII collagen is recognized by autoantibodies in patients with pemphigoid and linear IgA dermatosis

BACKGROUND: Type XVII collagen promotes adhesion of basal keratinocytes to epidermal basement membrane, and is the target of disease in patients with certain inherited or acquired blistering diseases. Two forms of type XVII collagen are produced by cultured human keratinocytes: a 180-kDa full-length, transmembrane protein, and a recently identified 120-kDa soluble fragment that corresponds to its collagenous ectodomain. OBJECTIVES: We aimed to determine the incidence and pattern of reactivity of autoantibodies against the 180- and 120-kDa forms of type XVII collagen in sera from 40 patients with bullous pemphigoid (BP), pemphigoid gestationis or cicatricial pemphigoid (CP), as well as six patients with linear IgA dermatosis (LAD). METHODS: Various immunochemical techniques were used. RESULTS: These studies found that the 120-kDa fragment of type XVII collagen was bound by circulating autoantibodies in 13 of 38 patients with BP or CP and all six patients with LAD. While many pemphigoid sera had specific reactivity against one but not both forms of this protein, autoantibodies from patients with LAD bound only the soluble ectodomain. CONCLUSIONS: These findings are consistent with the presence of both neoepitopes and cross-reactive epitopes on the ectodomain of type XVII collagen. The finding that sera from patients with LAD showed specific reactivity to epidermal basement membrane suggests that such neoepitopes are present in human skin and that their targeting by autoantibodies may contribute to disease pathogenesis.     

Place of human amniotic membrane immunoblotting in the diagnosis of autoimmune bullous dermatoses

Background Fine analysis of antiskin autoantibodies can contribute to the differential diagnosis of autoimmune bullous dermatoses. Objectives To develop a high‐performance immunoblotting method using human amniotic membrane as the antigen source, and to compare it with current laboratory methods. Methods Sera from 113 patients were tested by immunoblotting (IB), rat and monkey oesophagus and salt‐split skin indirect immunofluorescence (IIF), and enzyme‐linked immunosorbent assay (ELISA) quantification of anti‐BP180‐NC16a and anti‐BP230, or antidesmoglein (Dsg) 1 and 3 antibodies. There were 56 cases of bullous pemphigoid (BP), 22 cases of mucous membrane pemphigoid (MMP), eight cases of epidermolysis bullosa acquisita (EBA), two cases of bullous systemic lupus erythematosus (BSLE), 17 cases of pemphigus vulgaris (PV), and four cases each of pemphigus foliaceus (PF) and paraneoplastic pemphigus (PNP). Results In BP, the three methods had similar sensitivity (84–89%) for both anti‐BP180‐NC16a and anti‐BP230 antibody detection. In MMP, autoantibodies (mainly directed against BP180 or laminin 332 subunits) were detected in 77% of patients by IB, compared with only 9% by IIF on rat and monkey oesophagus and 36% on salt‐split skin, and 14% by anti‐BP180‐NC16a and anti‐BP230 ELISA. In patients with pemphigus, ELISA had 92% sensitivity for anti‐Dsg1 and 3, but IB and rat bladder IIF were necessary to confirm PNP by revealing specific and rare patterns (antidesmoplakin I/II, antienvoplakin and antiperiplakin antibodies). IB also revealed anticollagen VII antibodies in 60% of patients with EBA and BSLE, and antibodies to BP180, BP230 and Dsg3 in a few patients who were negative using the other two techniques. Conclusion Amniotic membrane immunoblotting is an interesting diagnostic tool for bullous diseases, as the entire panel of autoantibodies can be detected with a single extract. This method improves the identification of complex and heterogeneous autoimmune processes in conjunction with IIF and ELISA, and is particularly useful for MMP characterization.     

A child with localized vulval pemphigoid and IgG autoantibodies targeting the C-terminus of collagen XVII/BP180

Localized vulval pemphigoid of childhood (LVPC) has previously been reported in six girls. Clinical features and immunopathological data have suggested it to be a morphological variant of bullous pemphigoid. Epitope targets of the autoantibodies of these patients have not been defined in detail. We describe a 9-year-old girl with possible cicatricial LVPC and circulating IgG antibodies directed against native collagen XVII/BP180, its 120-kDa soluble ectodomain and against the C-terminus of collagen XVII/BP180. No reactivity was detected towards the NC16A domain of collagen XVII/BP180. Linear IgG and C3 deposits were found along the cutaneous basement membrane zone. On 1 mol/L salt-split skin, IgG autoantibodies were shown to bind to the epidermis, and the HLA type II allele DQB1*0301, a marker with significantly increased occurrence in patients with ocular and oral cicatricial pemphigoid, was identified in this patient. Our data suggest that LVPC is a variant of bullous pemphigoid in which direct immunofluorescence microscopy combined with immunoblot analysis can deliver valuable diagnostic information for differential diagnosis. However, differentiation between the scarring and non-scarring course of the disease cannot be made with the present diagnostic markers and therefore careful follow-up of patients with LVPC is required.     

Case of bullous pemphigoid coexisting with anti‐desmoglein autoantibodies

A 79‐year‐old Japanese woman had clinical and histopathological features of bullous pemphigoid, while direct immunofluorescence test revealed C3 and immunoglobulin G depositions in the lower cell surfaces of the epidermis in addition to those in the dermoepidermal junction. Chemiluminescent enzyme immunoassays were positive for desmoglein‐1 and ‐3 antibodies in addition to anti‐BP180 antibodies. In an immunoblotting study, antibodies against both 180‐kDa bullous pemphigoid antigen and 130‐kDa pemphigus vulgaris antigen were detected. Based on these results, bullous pemphigoid coexisting with anti‐desmoglein autoantibodies was diagnosed in this case.     

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.     

Case of subepidermal autoimmune bullous disease with psoriasis vulgaris reacting to both BP180 C‐terminal domain and laminin gamma‐1

A number of cases of psoriasis vulgaris developing bullous skin lesions have been diagnosed as either bullous pemphigoid with antibodies to the 180‐kDa bullous pemphigoid antigen (BP180) non‐collagenous 16a (NC16a) domain or anti‐laminin‐γ1 (p200) pemphigoid. We report a case of subepidermal bullous disease with psoriasis vulgaris, showing antibodies to both BP180 C‐terminal domain and laminin‐γ1. A 64‐year‐old Japanese man with psoriasis vulgaris developed exudative erythemas and tense bullae on the whole body but he did not have mucosal involvement. The blistering lesion showed subepidermal blisters histopathologically. In indirect immunofluorescence of 1 mol/L NaCl‐split skin, immunoglobulin (Ig)G antibodies reacted with both the epidermal and dermal side. Immunoblotting showed positive IgG with recombinant protein of BP180 C‐terminal domain and 200‐kDa laminin‐γ1 in normal human dermal extract.     

IgG, IgA and IgE autoantibodies against the ectodomain of BP180 in patients with bullous and cicatricial pemphigoid and linear IgA bullous dermatosis

BACKGROUND: Bullous pemphigoid (BP), linear IgA bullous dermatosis (LABD) and cicatricial pemphigoid (CP) are clinically distinct autoimmune bullous skin diseases characterized by autoantibodies against components of the epidermal basement membrane. Like most patients with BP, a significant subgroup of patients with CP has circulating IgG specific for BP180, a transmembraneous protein of hemidesmosomes. Moreover, sera of patients with LABD contain IgA autoantibodies reactive with a 97/120-kDa protein, LABD antigen 1, which is highly homologous to the extracellular portion of BP180. OBJECTIVES: We aimed to determine whether, in these diseases, autoantibody reactivity to BP180 is restricted to distinct immunoglobulin subtypes. METHODS: Utilizing a baculovirus-encoded form of the ectodomain of BP180, sera from patients with BP (n = 10), CP (n = 9), LABD (n = 10) and normal human control sera (n = 10) were analysed by immunoblot for IgG, IgA and IgE reactivity against BP180. RESULTS: All of 10 BP sera displayed IgG, IgA and IgE reactivity with BP180. Six and seven of nine CP sera, respectively, contained IgG and IgA autoantibodies reactive with BP180, but none of nine sera contained BP180-specific IgE. Nine of 10 LABD sera contained IgA, and six of 10 IgG, which was reactive with BP180, but none of 10 sera showed IgE reactivity to BP180. CONCLUSIONS: The presence of IgG and IgA autoantibody responses to BP180 in patients with three clinically distinct autoimmune bullous diseases indicates that an autoimmune response to the same distinct adhesion protein may lead to different clinical manifestations. It is therefore conceivable that variable epitopes of BP180 are targeted by the different autoantibody isotypes, resulting in the distinct clinical pictures.     

Possible paraneoplastic syndrome case of bullous pemphigoid with immunoglobulin G anti‐BP180 C‐terminal domain antibodies associated with psoriasis and primary macroglobulinemia

A 61‐year‐old Japanese man developed bullous skin lesions during topical therapy for psoriasis vulgaris. Physical examination demonstrated numerous tense bullae and scaly erythemas on the trunk and extremities. Histopathology of the skin biopsy demonstrated subepidermal bullae and lymphocytic infiltration with eosinophils in the dermis. Direct immunofluorescence revealed linear deposits of immunoglobulin (Ig)G, IgA and C3 along the basement membrane zone. Indirect immunofluorescence of 1 mol/L NaCl‐split skin showed IgG reactivity with both epidermal and the dermal sides. IgM reactivity with both the epidermal and dermal sides was also detected. Enzyme‐linked immunosorbent assays showed negative results for both BP180 and BP230. Immunoelectrophoresis of serum and bone marrow aspiration revealed underlying primary macroglobulinemia with M‐proteinemia of IgM‐κ type. Immunoblot analysis revealed IgG, but not IgM, antibodies to recombinant protein of BP180 C‐terminal domain. We diagnosed the present case as bullous pemphigoid with IgG anti‐BP180 C‐terminal domain autoantibodies associated with primary macroglobulinemia and psoriasis vulgaris. Systemic administration of prednisolone 30 mg/day resulted in dramatic improvement of both bullous and psoriatic skin lesions. When the bullous and psoriatic lesions relapsed, DRC chemotherapy (dexamethasone, rituximab and cyclophosphamide) for macroglobulinemia was performed. Then, the psoriatic lesions improved and the bullous lesions disappeared. We suggested that the present case may be paraneoplastic syndrome of bullous pemphigoid associated with primary macroglobulinemia and psoriasis vulgaris.     

Autoantibodies to the extracellular and intracellular domain of bullous pemphigoid 180, the putative key autoantigen in bullous pemphigoid, belong predominantly to the IgG1 and IgG4 subclasses

BACKGROUND: Autoantibodies to the extracellular domain (ECD) of bullous pemphigoid (BP) antigen 180 (BP180) are thought to play a crucial part in the pathophysiology of BP. OBJECTIVES: As the various IgG subclasses have different biological properties, we have sought to assess the relative isotype distribution of IgG to BP180 and their reactivity against the ECD and intracellular domain (ICD) of BP180. METHODS: The reactivity of 27 sera from patients with BP was assayed by immunoblotting against recombinant proteins covering the ECD and ICD of BP180. RESULTS: Twenty-seven (100%) and 21 (77%) of 27 BP sera, respectively, contained IgG1 and IgG4 autoantibodies binding to the ECD of BP180. Fourteen (82%) and six (35%) of the 17 BP sera that were reactive with the ICD of BP180 had autoantibodies of the IgG1 and IgG4 subclass, respectively. The profile of the isotype restriction appeared to be similar when the response to the ECD vs. that to the ICD was compared. IgG2 and IgG3 reactivity with BP180 was found less frequently. Patients with BP of longer duration showed a tendency to have, in addition to IgG1, an IgG4 response. CONCLUSIONS: Consistent with prior evidence indicating that subepidermal blister formation in BP is dependent upon complement activation, the frequent finding of complement-fixing IgG1 autoantibodies to both the ECD and ICD of BP180 might have pathogenic relevance in BP. These findings provide new insights relevant for our understanding of the immune response to BP180, the putative key autoantigen in BP.     

Correlation of autoantibodies against BP180/BP230 in response to topical corticosteroids in patients with bullous pemphigoid

Topical steroids are effective in treating bullous pemphigoid (BP). Autoantibodies against BP180 are related to disease activity, but correlation of these autoantibodies with response to topical steroid therapy has not yet been clearly evaluated. We investigate the usefulness of close and early monitoring of autoantibodies against BP180 and BP230 for assessment of response to therapy and early detection of therapeutic failure in BP patients treated topically. In eight BP patients under treatment with topical or systemic steroid therapy we retrospectively evaluated clinical course and autoantibodies against BP180 and BP230 as well as indirect immunofluorescence titres (IIF). Data were included at diagnosis, during hospitalization and follow‐ups. Autoantibodies against BP180 parallel disease activity in all topically and as well as systemically treated patients. Autoantibodies against BP230 correlated in five out of eight patients. Autoantibodies directed against BP180 and, to a lesser degree, against BP230 correlate with the clinical course of topically treated BP patients. Monitoring autoantibodies against BP180 is a useful tool to evaluate the efficacy of topical therapy in BP.     

Bullous pemphigoid sera react specifically with various domains of BP230, most frequently with C-terminal domain, by immunoblot analyses using bacterial recombinant proteins covering the entire molecule

By immunoblot analyses of normal human epidermal extracts, the 230 kDa bullous pemphigoid antigen (BP230) is recognized by most bullous pemphigoid sera. By polymerase chain reaction using keratinocyte cDNA library as a template, we successfully amplified 3 cDNAs of about 3 kb, which covered whole human BP230 molecule. By inserting the cDNAs into bacterial expression vector pGEX, we prepared 3 different recombinant glutathione-S-transferase-fusion proteins, which roughly presented N-terminal domain, central rod domain and C-terminal domain of BP230. By immunoblotting using these 3 recombinant proteins, we demonstrated that the majority of bullous pemphigoid sera reacted clearly with multiple recombinant proteins of BP230, most frequently with C-terminal domain. We also examined sera of pemphigus vulgaris, pemphigus foliaceus and herpetiform pemphigus that showed BP230-like protein band by immunoblotting of epidermal extracts, as well as paraneoplastic pemphigus, for reactivity with the 3 recombinant proteins. In the study, we found that only very few of these non-bullous pemphigoid sera reacted with some of the recombinant proteins. These results indicate that the BP230 is specifically reacted by bullous pemphigoid sera, and that the immunoblotting using the BP230 recombinant proteins should be a useful tool for the diagnosis of bullous pemphigoid.     

Case of localized bullous pemphigoid with unique clinical manifestations in the lower legs

We report the case of a 71-year-old Japanese woman who presented with persistent band-like erosions in the lower legs. Histological examination suggested subepidermal blister formation. Direct and indirect immunofluorescence studies revealed tissue-deposited and circulating immunoglobulin G autoantibodies against the basement membrane. Western blotting revealed autoantibodies to BP230, but not to BP180. Based on these findings, the patient was diagnosed as having a localized type of bullous pemphigoid. We suggest that the unique clinical manifestations in this patient could be attributable to bacterial or fungal infection, and/or mechanical trauma, such as the pressure of her socks.     

Omalizumab as an alternative therapeutic tool in the treatment of bullous pemphigoid: A case report

Bullous pemphigoid (BP) is an acquired autoimmune bullous disease characterized by autoantibodies against the hemidesmosomal proteins found in the basal keratinocytes of the basement membrane zone (BMZ): a 180 kDa protein (type XVII collagen) mainly and the 230 kDa antigen. There is such evidence that the antibodies against the BMZ components are not only of IgG type, but also this bullous disease may have IgE antibodies directed to the BMZ that contribute to the pathogenesis of the disorder. IgE is not only thought to contribute to the pathogenesis of BP, it has also been suggested that eosinophils play a role in the development of the first signs associated with BP. A humanized monoclonal antibody directed to IgE, omalizumab, is approved for the treatment of severe asthma and chronic spontaneous urticaria, and it may be useful in the treatment of BP in the first stages of the disease.     

Rituximab in autoimmune bullous diseases: mixed responses and adverse effects

BACKGROUND: Intolerably high doses of systemic corticosteroids and additional immunosuppressants may be required to control disease activity in autoimmune bullous skin diseases. New therapeutic options are needed for such patients. OBJECTIVES: To determine the efficacy and adverse effects of adjuvant rituximab. METHODS: Seven patients with refractory autoimmune blistering diseases (pemphigus vulgaris, PV, n = 4; bullous pemphigoid, BP, n = 2; mucous membrane pemphigoid, MMP, n = 1) were treated four times with rituximab at an individual dose of 375 mg m(-2) at weekly intervals. RESULTS: All lesions cleared in three patients (two PV, one BP), while they were reduced by more than 50% in three others (two PV, one BP). The concomitant immunosuppressive medication was reduced in five patients (four PV, one BP). The patient with MMP developed bilateral blindness while nasopharyngeal lesions resolved. Three patients (two BP, one PV) experienced severe adverse events including fatal pneumonia. CONCLUSIONS: Adjuvant B-cell depletion by rituximab is effective in otherwise therapy-resistant bullous autoimmune disorders but may be associated with substantial adverse effects including fatal outcomes.