Role of BP230 autoantibodies in bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune disease associated with subepidermal blistering due to autoantibodies directed against BP180 and BP230. BP180 is currently considered as the major pathogenic autoantigen. However, previous clinical findings suggested that anti-BP230 autoantibodies alone can cause skin lesions in animal models and many BP patients. The characteristics of BP230 and the pathogenic roles of anti-BP230 antibodies have been proposed. First, at the molecular level, BP230 mediates the attachment of keratin intermediate filaments to the hemidesmosomal plaque and interacts with other constituents of hemidesmosomes. Second, the presence of BP230 autoantibodies may correlate with specific clinical features of BP. The immunoglobulin (Ig)G autoantibodies from BP patients react mainly against the C-terminus of BP230, while the IgE autoantibodies are still inconclusive. Third, in vivo, autoantibodies against BP230 involved in the disease may not only induce the inflammatory response but also impair the structural stability of hemidesmosomes. This article reviews recently published work about the role of BP230 and its antibodies, including IgG and IgE, aiming to find clues of its clinical association and lay the foundation for the research on the pathogenicity of antibodies against BP230.     

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.     

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.     

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.     

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.     

131例神经系统疾病患者血清中抗BP180和抗BP230抗体的检测

目的：检测神经系统疾病患者血清中抗BP180、抗BP230和抗基底膜带抗体的阳性率。方法：收集神经系统疾病患者和正常对照血清,采用酶联免疫吸附试验（ELISA）和间接免疫荧光（IIF）检测两组血清中抗BPl80NC16A抗体和BP230抗体水平。结果：共收集到131例神经系统疾病患者血清(脑卒中109例,脑肿瘤17例,其他神经系统疾病19例)和131例正常对照血清。病例组中抗BP180NC16A1阳性率为1.45%,低于对照组的3.05%,差异具有统计学差异（P = 0.009）,病例组中抗BP230抗体阳性率5.34%与对照组（2.29%）比较,差异无统计学意义。IIF检测抗基底膜带抗体结果均为阴性。结论：抗BP180NC16A抗体在神经系统疾病患者中有较高的阳性率,可能与神经系统疾病患者合并大疱性类天疱疮相关。     

False-negative results in immunoblot assay of serum IgA antibodies reactive with the 180-kDa bullous pemphigoid antigen: the importance of primary incubation temperature

BACKGROUND: Different subepidermal autoimmune blistering skin disorders are characterized by linear deposition of IgA, sometimes accompanied by linear IgG, along the epidermal basement membrane zone. Identification of the targeted autoantigen is usually attempted by immunoblotting. Although immunoblotting works well for human IgG, the method is less successful for IgA and often no or only faint signals are obtained. OBJECTIVES: To improve the method of immunoblotting for diagnosis of IgA-mediated bullous dermatoses. METHODS: Eleven sera, selected from patients with linear deposition of IgA along the epidermal basement membrane zone in vivo, were tested by immunoblotting for antigen specificity using different primary incubation temperatures. RESULTS: No reliable information regarding IgA antigen specificity was obtained when the primary incubation was undertaken at room temperature. In 10 of 11 sera, IgA bound to the 180-kDa bullous pemphigoid antigen (BP180) when the primary incubation temperature was increased to 37 degrees C. CONCLUSIONS: Primary incubation at room temperature may result in false-negative results in the IgA-BP180 immunoblot assay.     

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.     

Pyodermatitis-pyostomatitis vegetans with circulating autoantibodies to bullous pemphigoid antigen 230

We describe a woman from Korea with pyodermatitis-pyostomatitis vegetans associated with ulcerative colitis. On immunofluorescence examination, she demonstrated in vivo bound and circulating IgG antibasement membrane zone antibodies. The immunoelectron microscopy and immunoblot analysis showed that the antibodies reacted with the bullous pemphigoid antigen 230. We consider that the circulating autoantibodies to the bullous pemphigoid antigen 230 in this patient were an epiphenomenon, resulting from epidermal damage induced by inflammation of pyodermatitis-pyostomatitis vegetans.     

Usefulness of Enzyme-linked Immunosorbent Assay Using Recombinant BP180 and BP230 for Serodiagnosis and Monitoring Disease Activity of Bullous Pemphigoid

Background

Bullous pemphigoid (BP) is an autoimmune subepidermal bullous disease associated with autoantibodies against BP180 and BP230. Enzyme-linked immunosorbent assay (ELISA) is a sensitive tool for the detection of immunoglobulin G (IgG) anti-BP180 and anti-BP230 autoantibodies.

Objective

The aim of this study was to evaluate the usefulness of ELISA for diagnosing and monitoring the disease activity of BP.

Methods

We evaluated serum IgG levels of anti-BP180 and anti-BP230 autoantibodies in 47 BP patients, 16 epidermolysis bullosa aquisita patients, and 15 healthy volunteers using ELISA. Through retrospective review of the medical records, the clinical characteristics of BP including disease activity, duration, pruritus severity and peripheral blood eosinophil counts were assessed.

Results

The sensitivity of BP180 ELISA was 97.9%, BP230 ELISA 72.3%, and a combination of the two was 100%. The specificity of BP180 ELISA was 90.3%, BP230 ELISA 100%, and a combination of the two was 90.3%. BP180 ELISA scores showed strong associations with disease activity, pruritus severity, peripheral blood eosinophil counts, and disease duration, whereas BP230 ELISA scores did not.

Conclusion

BP180 and BP230 ELISAs are highly sensitive methods for the diagnosis of BP, and BP180 ELISA, in particular, is a sensitive tool for monitoring the disease activity of BP.     

Clinical features and practical diagnosis of bullous pemphigoid

Bullous pemphigoid (BP) represents the most common autoimmune subepidermal blistering disease. BP typically affects the elderly and is associated with significant morbidity. It has usually a chronic course with spontaneous exacerbations. The cutaneous manifestations of BP can be extremely protean. While diagnosis of BP in the bullous stage is straightforward, in the non-bullous stage or in atypical variants of BP signs and symptoms are frequently non-specific with eg, only itchy excoriated, eczematous, papular and/or urticarial lesions that may persist for several weeks or months. Diagnosis of BP critically relies on immunopathologic examinations including direct immunofluorescence microscopy and detection of serum autoantibodies by indirect immunofluorescence microscopy or BP180-ELISA.     

Cicatricial pemphigoid: serial titres of circulating IgG and IgA antibasement membrane antibodies correlate with disease activity

We have recently shown in a cohort of patients (n = 67) with mucous membrane pemphigoid, 63 of whom had cicatricial pemphigoid (CP), that the presence of both IgG and IgA circulating antibasement membrane zone antibodies was associated with a more severe and persistent disease. In this study we sought to ascertain whether in CP, serial titres of IgG and IgA might provide a reliable marker of disease activity. Serum titres for IgG and IgA antibodies were assayed at 6- to 12-monthly intervals in 56 patients over 32.2 +/- 20.3 (mean +/- SD) months. Antibody titres were correlated with the clinical score recorded at each follow-up visit. Sequential titres for both IgG (P < 0.001) and IgA (P = 0.015) were significantly associated with variations in disease activity. Greatest improvement was seen in patients with the greatest change in either IgG or IgA antibody titre. We suggest that serial antibody titres may therefore be useful in the assessment and management of CP.     

大疱性类天疱疮患者外用糖皮质激素治疗抵抗的相关因素分析

目的:依据临床和实验室数据,分析大疱性类天疱疮(BP)患者外用糖皮质激素(简称激素)治疗抵抗的相关因素。方法:收集BP患者64例,其中外用激素治疗有效组(即外用激素治疗4周内,连续3 d,每日新发水疱数<3个,以下简称有效组)22例,外用激素治疗无效组(即外用激素治疗4周内皮损未控制,连续3 d,每日新发水疱数≥3个,以下简称无效组)42例。对2组BP患者的皮损类型进行统计,比较2组患者的大疱性类天疱疮疾病面积指数(BPDAI)评分、外周血中白蛋白浓度和嗜酸性粒细胞(EOS)计数以及外周血中抗BP180和抗BP230 IgG抗体、总IgE、抗BP180和抗BP230 IgE抗体浓度。结果:有效组患者的皮损以单纯水疱为主(68%),无效组则以红斑水疱为主(63%)。无效组患者的BPDAI评分、EOS计数、总IgE、抗BP180 IgG抗体、抗BP230 IgG抗体浓度及抗BP230 IgE抗体浓度均较有效组患者明显增高,差异具有统计学意义(P<0.05);而2组患者白蛋白水平及抗BP180 Ig E抗体浓度无明显差异。结论:除BPDAI评分及特异性IgG水平之外,还可根据BP...     

Alpha 6 beta 4 integrin abnormalities in junctional epidermolysis bullosa with pyloric atresia

Junctional epidermolysis bullosa with pyloric atresia (JEB-PA) (MIM 226730) is an autosomal recessive disorder resulting from mutations in the genes encoding alpha 6 beta 4 integrin (ITGA6 and ITGB4). Clinically, it is characterized by mucocutaneous fragility and gastrointestinal atresia, which most commonly affects the pylorus. Additional features of JEB-PA include involvement of the urogenital tract, aplasia cutis and failure to thrive. While most affected individuals have a poor prognosis resulting in death in infancy, others have milder clinical features and a better prognosis. We report two previously undescribed homozygous ITGB4 mutations in two unrelated families, which resulted in severe skin blistering, pyloric atresia and lethality in infancy. Delineation of the mutations was used to undertake DNA-based prenatal diagnosis in subsequent pregnancies at risk for recurrence in both families. We review all previously published ITGA6 and ITGB4 mutation reports to help define genotype--phenotype correlation in this rare genodermatosis.     

Childhood bullous pemphigoid successfully treated with diaminodiphenyl sulfone

Bullous pemphigoid (BP) is an acquired autoimmune blistering disease which predominantly affects the elderly. It is rare in children and infants. We reported a 14-year-old girl presenting with a month history of relapsing tense bullae on the face and extremities. Histopathological examination of the lesional skin revealed a subepidermal bulla with infiltration of eosinophils, neutrophils, and lymphocytes. Direct immunofluorescence showed linear deposits of IgM and C3 at the basement membrane zone. Indirect immunofluorescence using normal human skin sections as a substrate detected IgG anti-basement membrane zone antibodies in the patient's serum and that using 1M NaCl split skin sections showed that the patient's antibodies bound to the epidermal side of the split skin. Immunoblot analysis using normal human epidermal extracts demonstrated the presence of autoantibodies against the 230-kDa BP antigen. Furthermore, the patient's serum reacted with the recombinant protein of the NC16a domain of the 180-kDa BP antigen by immunoblot analysis and enzyme-linked immunosorbent assay. Our patient showed significant improvement of the skin lesions with systemic administration of diaminodiphenyl sulfone.     

Development of a novel ELISA system for detection of anti-BP180 IgG and characterization of autoantibody profile in bullous pemphigoid patients

BACKGROUND: The NC16A immunodominant region of the bullous pemphigoid (BP) antigen BP180 has been used to develop several enzyme-linked immunosorbent assays (ELISAs) as diagnostic tools for BP autoantibody detection. OBJECTIVES: Because BP180 autoantibody reactivity is not restricted to NC16A, we have investigated the possibility of developing an ELISA based on selected epitopes additional to this immunodominant region. METHODS: Initially 78 BP sera were tested using an NC16A ELISA and IgG reactivity was detected in 64 BP sera (82%). The 14 NC16A-negative BP sera were then analysed by immunological screening against seven BP180-specific epitopes. Recombinant phages displaying BP180 epitopes were grown as plaques, blotted onto a nitrocellulose filter and incubated with BP sera. RESULTS: Three and five NC16A-negative BP sera reacted with epitopes AA 1080-1107 and AA 1331-1404 of the BP180 ectodomain, respectively. Thus, a novel ELISA with GST-1080 and GST-1331 (GST-1080/1331) was developed: 32 of 78 BP sera (41%) proved positive by this assay. The combined use of ELISAs with GST-NC16A and GST-1080/1331 detected IgG reactivity in 72 of 78 BP sera, increasing the sensitivity from 82% to 92%. In addition, autoreactivity against the three extracellular epitopes appeared to be related to the presence of both skin and mucosal involvement as assessed by Fisher's exact probability test. CONCLUSIONS: Our findings further characterize the autoimmune response in BP by identifying a subgroup of NC16A-negative patients who react with different BP180 extracellular epitopes. The developed ELISA system appears more sensitive than the ELISA based on NC16A alone and also informative about the epitope profile of BP patients.     

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.