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.     

Cicatricial pemphigoid with circulating autoantibodies to beta4 integrin, bullous pemphigoid 180 and bullous pemphigoid 230

Cicatricial pemphigoid is a heterogeneous group of autoimmune subepidermal blistering diseases associated most commonly with autoantibodies to bullous pemphigoid (BP)180 and less frequently with those to laminin 5 or type VII collagen. In addition, a few cases have been described with autoantibodies to the beta4 subunit of alpha6beta4 integrin. We describe a patient with extensive disease of ocular, oral, pharyngeal, laryngeal and genital mucous membranes that healed with scarring of conjunctivae. IgG autoantibodies bound to the dermal-epidermal junction on direct immunofluorescence (IF) microscopy and to the epidermal side of 1 mol L(-1) NaCl-split skin on indirect IF microscopy. Our patient's circulating IgG recognized a 205-kDa protein in extracts of 293T cells transfected with the beta4 subunit of alpha6beta4 integrin and in the cell extract of DJM-1 cells. Our patient's IgG and IgA autoantibodies also reacted with full-length BP180 derived from epidermal extracts and the ectodomain of BP180 (LAD-1) derived from culture supernatant of keratinocytes. In addition, a weak IgG reaction with BP230 was noted. The disease rapidly responded to dexamethasone-cyclophosphamide pulse therapy, and immunoblot reactivity to both beta4 integrin and BP180 decreased according to disease activity.     

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.     

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.     

Childhood bullous pemphigoid associated with IgA antibodies against BP180 or BP230 antigens

Linear IgA bullous dermatosis (LABD) comprises a heterogeneous group of subepidermal blistering disorders characterized by in situ bound IgA antibodies in epidermal basement membrane. We report three children presenting clinical and immunopathological features characteristic of LABD. By immunoblotting, the three patients' sera contained IgA antibodies that reacted against the bullous pemphigoid (BP) antigen 180 and or BP230, molecular markers for BP. In addition, IgG antibodies directed against the ectodomain of BP180 were detected by an enzyme-linked immunosorbent assay using a eukaryotic recombinant form of BP180. Consistent with recent studies suggesting that the LABD antigen 1, the predominant autoantigen of LABD, is either a proteolytic product of BP180 or an isoform of the BP180 gene, our findings indicate that a subset of children with features of LABD have a distinct form of BP associated with an IgA response.     

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。     

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.     

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...     

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.     

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.     

大疱性类天疱疮患者血清抗BP180分子不同表位自身抗体定量分析及亲和力分析

目的 探讨大疱性类天疱疮（BP）患者血清抗BP180分子不同表位的自身抗体量。方法 制备BP180分子NC16A片段的不同抗原表位区NC16A-1、NC16A-2和NC16A-3,利用柱亲和层析的方法从10例BP患者血清中分别纯化抗不同表位区的自身抗体,定量,并用硫氰酸盐洗脱法测定抗NC16A-1、抗NC16A-2和抗NC16A-3自身抗体的相对亲和力。结果 经亲和层析纯化获得针对BP180-NC16A不同表位区的自身抗体,从20 mg总IgG中纯化抗NC16A-1、NC16A-2和NC16A-3自身抗体的产量分别为（49.0 ± 20.7） μg、（117.7 ± 22.4） μg和（39.5 ± 18.9） μg。抗NC16A-2自身抗体的量和亲和力水平均明显高于其他两个表位区的自身抗体。结论 BP致病性自身抗体所识别的主要抗原表位可能位于BP180分子的NC16A-2表位区（aa507-aa520）。     

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).     

IgG autoantibody reactivity against bullous pemphigoid (BP) 180 and BP230 in elderly patients with pruritic dermatoses

Background  Pruritic dermatoses of the elderly often pose a diagnostic and therapeutic challenge. Specifically, a prodromal phase of bullous pemphigoid (BP) has to be considered in patients with pruritic lesions of polymorphic appearance. These conditions frequently do not fulfil all the clinical, histological and immunopathological criteria for establishing the diagnosis of BP.
Objectives  To investigate IgG reactivity against the autoantigens of BP, BP180 and BP230, by enzyme-linked immunosorbent assay, in elderly patients affected with various pruritic disorders who had never experienced clinically apparent blisters.
Methods  The sera of 15 elderly patients with pruritic disorders (group I) were tested for IgG reactivity against BP180 and BP230. Also included were 30 patients with full-blown BP (group II) and 25 age-matched patients with immediate-type allergic reactions (group III).
Results  Thirty-three per cent of the patients with pruritic disorders (group I) showed IgG against BP230 and/or BP180: four of 15 patients had IgG against BP230 while two of the 15 group I patients were BP180 reactive. All the BP sera (group II) showed IgG reactivity against BP180 and/or BP230. Notably, two of 25 control sera (group III) showed IgG reactivity against either BP180 or BP230.
Conclusions  The present findings suggest that IgG reactivity against BP230 (i.e. the COOH terminus), and to a lesser extent against BP180, is a common finding in pruritic disorders of the elderly with a wide clinical spectrum. IgG-mediated autoimmunity against the intracellular BP230 may facilitate a chronic, inflammatory response eventually leading to full-blown BP which is presumably associated with IgG against BP180.     

Plectin, an unusual target antigen in bullous pemphigoid

BACKGROUND: Bullous pemphigoid (BP) is a blistering disease associated with autoantibodies directed against two components of hemidesmosomes, BP180 and BP230. OBJECTIVES: To assess whether BP patients have autoantibodies targeting plectin, another hemidesmosomal component showing extensive homology to BP230. METHODS: Examination of sera from 16 patients with BP, using immunoprecipitation studies followed by immunoblotting. RESULTS: Serum of one of the 16 (6%) patients with BP contain autoantibodies binding to plectin, while no reactivity was found with sera from three control subjects. Sera from all 16 BP patients immunoprecipitated BP230 from extracts of biosynthetically radiolabelled human keratinocytes. CONCLUSIONS: Our results indicate that sera from BP patients might contain autoantibodies binding to plectin. Although this protein and BP230 are closely sequence-related, the occurrence of autoantibodies binding to plectin is a rare phenomenon in BP.     

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.     

Trichophytic granuloma associated with bullous pemphigoid

A 69-year-old Japanese man developed multiple nodular granulomatous cutaneous lesions caused by Trichophyton rubrum during treatment of bullous pemphigoid. One and a half months after the initiation of oral corticosteroid therapy, the lesions appeared. He had suffered from tinea pedis for several decades. Oral ketoconazole was given for 6 weeks with remarkable improvement. Trichophytic granuloma is a rare but important complication of bullous pemphigoid.     

BP180NC16a-ELISA对大疱性类天疱疮血清学诊断的评价

目的 评价BP180NC16a-ELISA对大疱性类天疱疮血清学诊断的效能.方法 BP患者42例,对照组42例(其中正常人对照24例,天疱疮18例),在患者用药前采血,比较BP180NC16a-ELISA和盐裂试验免疫荧光(IIF)检测的结果.结果 用BP180NC16a-ELISA检测时,BP患者中有1例呈阴性反应,其敏感性为97.62%;正常人对照组中有1例呈阳性反应,其特异性为97.62%,且BP180NC16a-ELISA法的A值与IIF滴度之间无相关性.结论 BP180NC16a-ELISA在疾病初始阶段是检测血清中抗BP180抗体的有效方法.     

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.