Pemphigus Vulgaris Autoantibody Response is Linked to HLA-DQB10503 in Pakistani Patients

ABSTRACT: Pemphigus vulgaris (PV) is an autoimmune disease of the skin and mucous membranes characterized by an autoantibody response against an epidermal cadherin. We performed high resolution HLA class II typing in 19 patients with PV from Rawalpindi, Pakistan and 19 non-Jewish European PV patients from Boston by sequence-specific oligonucleotide probe hybridization. The results were compared with two separate ethnically matched control populations. We found that PV patients from Pakistan had significantly increased frequencies of DRB1*1404 ( p = 0.01), DQA1*0101 ( p = 0.02), and DQB1*0503 ( p = 0.01). Among the patients of non-Jewish European ancestry, DRB1*1401 ( p < 10⁻⁶), DQA1*0101 ( p < 10⁻⁵) and DQB1*0503 ( p < 10⁻⁶), were increased in PV patients. Formal linkage analysis between the major histocompatibility complex and the PV antibody was performed in 67 relatives of the 19 Pakistani patients. The results showed strong evidence for linkage of HLA-DRB1*1404, DQA1*0101, DQB1*0503, with the presence of PV antibody in relatives’ families with a significant logarithm of the odds score of 6.06. Based on the three dimensional structure of class II molecules, we propose that HLA-DQA1*0101 and DQB1*0503, encode a negatively charged P9 peptide binding pocket of the DQ molecule and are significantly associated with susceptibility to PV in non-Jewish populations.     

Pemphigus vulgaris: the role of IL-1 and IL-1 receptor antagonist in pathogenesis and effects of intravenous immunoglobulin on their production

Intravenous immunoglobulin (IVIG) is increasingly being used for the treatment of autoimmune diseases. In the present report, the role of IVIG on in vivo and in vitro production of IL-1 and IL-1 receptor antagonist (Ra) was studied in patients with pemphigus vulgaris (PV). Serum samples from 20 untreated patients with active PV prior to initiation of systemic therapy, 20 patients receiving IVIG treatment, 20 patients in clinical remission after conventional therapy, and 20 normal human controls were studied to determine the serum levels of IL-1alpha, IL-1beta, and IL-1Ra. The in vitro production of these cytokines was measured in the culture supernatant of peripheral blood mononuclear cells (PBMC) from 10 PV patients immediately before and after IVIG therapy and from age and sex-matched 10 healthy donors simultaneously. Elevated levels of IL-1alpha and IL-1beta were detected (i) in the serum of untreated PV patients with active disease prior to systemic therapy and (ii) before IVIG infusions in patients receiving IVIG therapy. These increased levels are statistically significant when compared to the levels in healthy controls (P < 0.01). A marked reduction of IL-1alpha and IL-1beta was detected (i) in the serum of patients in prolonged clinical remission and (ii) immediately after IVIG infusion in those patients on IVIG therapy. Increased level of IL-1Ra was detected in PV patients in prolonged clinical remission and after IVIG infusion in those receiving IVIG therapy. These differences were statistically significant when compared to the levels in normal controls and to the levels in the sera of patients with active disease (P < 0.01) or just before the beginning of IVIG infusion (P < 0.01). Similar differences in the levels of IL-1alpha, IL-1beta, and IL-1Ra were found in the culture supernatant of PBMC isolated from the PV patients pre and post IVIG therapy. These observations suggests that, compared to normal controls, patients with active PV have reversed levels of IL-1alpha, IL-1beta, and IL-1Ra. IVIG therapy may down-regulate production of IL-1alpha and IL-1beta and enhance production of IL-1Ra, in vivo and in vitro. This might be one of the important mechanisms by which IVIG produces its early therapeutic effects in pemphigus vulgaris.     

Linear IgA bullous disease limited to the eye: a diagnostic dilemma: response to intravenous immunoglobulin therapy

PURPOSE: To report on a diagnostic dilemma and treatment challenge in a patient with chronic cicatrizing conjunctivitis without involvement of skin and other mucous membranes persisting for 6 years and not responding to topical and systemic steroids. DESIGN: Interventional case report. METHODS: We performed direct immunofluorescence of the conjunctiva with fluorescein-conjugated rabbit antihuman antibodies against immunoglobulin A, G, and M, complement 3 component, and fibrinogen. To investigate the presence of circulating antibodies in patient's serum, indirect immunofluorescence using normal human conjunctiva, normal human skin, and monkey esophagus as substrate was done. In addition, we did immunoblot analysis using normal human epidermis as substrate to determine the molecular weight of an antigen. The patient was treated with intravenous immunoglobulin (IVIg). The correlation between the titer of circulating antibodies and the activity of conjunctival inflammation at various intervals during the course of IVIg therapy was demonstrated by immunoblot assay with serial dilutions of the patient's serum. The highest dilution at which the binding was visible was considered the titer. RESULTS: Direct immunofluorescence of the conjunctiva and indirect immunofluorescence with both salt split skin and conjunctiva as substrate disclosed linear deposition of immunoglobulin A (IgA) at the epithelial basement membrane. Immunoblot analysis demonstrated the presence of IgA circulating antibodies in patient's serum directed against a 97kDa protein in human epidermis. A continuous decrease in the titer of these antibodies correlating to improvement of clinical symptoms was observed during IVIg therapy. CONCLUSIONS: Use of a nonconventional diagnostic tool (immunoblot analysis), in addition to conventional immunohistologic studies, might be helpful in establishing the diagnosis of patients with chronic cicatrizing conjunctivitis. On the basis of results of these laboratory tests and clinical presentation, we believe that this patient has linear IgA bullous disease limited to the eye. IVIg therapy decreased the titer of circulating antibodies and induced a remission in this patient.     

Use of recombinant pemphigus vulgaris antigen in development of ELISA and IB assays to detect pemphigus vulgaris autoantibodies

Aim/Objective The objectives of this study are: (1) to measure the titers of pemphigus vulgaris (PV) autoantibody in the sera of patients with active disease, using three different assays: (a) Indirect immunofluorescence (IIF) using monkey esophagus as a substrate, (b) immunoblot (IB) and, (c) enzyme-linked immunosorbent assay (ELISA) using recombinant PV antigen (rPVA). (2) To compare the sensitivity of these three assays. Background The titer of PV autoantibodies and disease severity and extent do not always correlate. This could be due to the lack of consistency and specificity of the substrate. Different results are obtained using different substrates. A standard substrate with uniformly controlled source of antigen would be more useful and clinically beneficial. Methods In this study we studied 25 PV patients, six each with bullous pemphigoid (BP), ocular cicatricial pemphigoid (OCP), mucous membrane pemphigoid (MMP), and herpes gestationis (HG), and sera from 16 normal subjects. IIF was used to determine the PV autoantibody using monkey esophagus. IB assay was used according to standard protocol using normal human epidermis and rPVA as substrates. ELISA was performed using rPVA as antigens expressed in E. coli. Results Sera of all 25 PV patients showed binding to the rPVA, normal human sera and the sera from the six BP, six OCP, six MMP, and six HG patients did not show any binding. In addition, we used antisera from rabbits immunized with PVA peptides (Bos-1, Bos-6) which also showed binding to rPVA, whereas normal rabbit sera did not show any reactivity. ELISA and IB titers in all the patients were 2.5 to 160 times higher than with the conventionally used IIF assay. The titers of the PV specific autoantibody measured using the rPVA did not show statistically significant differences between the ELISA and IB assays. Conclusions IB and ELISA are superior to IIF in evaluating the antibody levels in PV patients. ELISA is more practical and is preferable to IB and is recommended for clinical use.     

A model of hepatic amoebiasis in random bred mice

This study describes a model of hepatic amoebiasis in random bred mice (MF2). Mice were infected by introducing liver tissue from hamsters (Mesocricetus auratus), containing about 5 X 10(4) trophozoites of Entamoeba histolytica, between adjacent liver lobes. Direct inoculation of xenic E. histolytica resulted in mortality within 24 h, whereas monoxenic and axenic strains failed to produce any lesions. Serial mouse liver passage resulted in increased lesion score, number of metastatic abscesses, and mortality. Metronidazole 150 mg/kg produced complete healing of the abscess. It is expected that this model will be useful to study host-parasite interactions, immunology and experimental chemotherapy of amoebiasis.     

Structural basis for major histocompatibility complex (MHC)-linked susceptibility to autoimmunity: charged residues of a single MHC binding pocket confer selective presentation of self-peptides in pemphigus vulgaris.

Human T-cell-mediated autoimmune diseases are genetically linked to particular alleles of MHC class II genes. Susceptibility to pemphigus vulgaris (PV), an autoimmune disease of the skin, is linked to a rare subtype of HLA-DR4 (DRB1*0402, 1 of 22 known DR4 subtypes). The PV-linked DR4 subtype differs from a rheumatoid arthritis-associated DR4 subtype (DRB1*0404) only at three residues (DR beta 67, 70, and 71). The disease is caused by autoantibodies against desmoglein 3 (DG), and T cells are thought to trigger the autoantibody production against this keratinocyte adhesion molecule. Based on the DRB1*0402 binding motif, seven candidate peptides of the DG autoantigen were identified. T cells from four PV patients with active disease responded to one of these DG peptides (residues 190-204); two patients also responded to DG-(206-220). T-cell clones specific for DG-(190-204) secreted high levels of interleukins 4 and 10, indicating that they may be important in triggering the production of DG-specific autoantibodies. The DG-(190-204) peptide was presented by the disease-linked DRB1*0402 molecule but not by other DR4 subtypes. Site-directed mutagenesis of DRB1*0402 demonstrated that selective presentation of DG-(190-204), which carries a positive charge at the P4 position, was due to the negatively charged residues of the P4 pocket (DR beta 70 and 71). DR beta 71 has a negative charge in DRB1*0402 but a positive charge in other DR4 subtypes, including the DR4 subtypes linked to rheumatoid arthritis. The charge of the P4 pocket in the DR4 peptide binding site therefore appears to be a critical determinant of MHC-linked susceptibility to PV and rheumatoid arthritis.     

Correlation of peptide specificity and IgG subclass with pathogenic and nonpathogenic autoantibodies in pemphigus vulgaris: a model for autoimmunity.

Pemphigus vulgaris (PV) is a rare, potentially fatal, autoimmune disease that affects the skin and mucous membranes. The PV antigen (PVA) has been characterized as desmoglein 3. PV patients carry HLA-DR4- or HLA-DR6-bearing extended haplotypes. We recently demonstrated that patients with active disease have high titers of PV autoantibodies of the IgG1 and IgG4 subclasses. Patients in remission, healthy unaffected relatives, and some MHC-matched normal individuals have low levels of PV autoantibodies, which are IgG1 only. Furthermore, intraperitoneal injection of IgG from patients with active disease caused clinical disease in mice, but IgG from patients in remission, healthy relatives, or MHC-matched normal individuals did not. We prepared 12 peptides of 30 amino acids each (peptides Bos 1-12) spanning the extracellular domain of PVA. Patients with active disease recognize peptides Bos 1 and Bos 6 with high titers of IgG1 and IgG4 autoantibodies. Patients in remission have IgG1 autoantibodies to peptide Bos 1 only, in statistically significantly lower titers (P < 0.01). They no longer have IgG4 subclass autoantibodies to peptide Bos 6. Healthy relatives and normal unrelated individuals have low levels of only IgG1 autoantibodies that recognize only Bos 1. In vitro studies indicate that Bos 6-specific IgG and, to a lesser extent, Bos 1-specific IgG can cause acantholysis. Our data suggest that Bos 6-specific IgG4 is probably the main acantholytic autoantibody, while Bos 1-specific IgG4 may act as a facilitator or enhancer of the process. In this study we illustrate some of the paradigms that demonstrate the interactions between the MHC, subclass of autoantibodies, and peptide specificities of the autoantibodies in the autoimmune process. Thus, PV provides an important model to study the pathogenesis of autoimmunity.     

The role of antibody to human beta4 integrin in conjunctival basement membrane separation: possible in vitro model for ocular cicatricial pemphigoid.

PURPOSE: To demonstrate the specific binding of autoantibodies present in the sera of patients with ocular cicatricial pemphigoid (OCP) to human beta4 integrin present in the normal human conjunctiva (NHC) and to study the role of OCP autoantibodies and antibody to human beta4 integrin in the pathogenesis of subepithelial lesion formation in OCP. METHODS: Indirect immunofluorescence assay and in vitro organ culture method using NHC were used. Sera and IgG fractions from 10 patients with OCP; immunoaffinity-purified OCP autoantibody; antibodies to human beta4, beta1, alpha6, and alpha5 integrins; and sera from patients with pemphigus vulgaris, bullous pemphigoid (BP), and chronic atopic and chronic ocular rosacea cicatrizing conjunctivitis; and normal human serum (NHS) were used. RESULTS: Nine of 10 OCP sera or IgG fractions, immunoaffinity-purified OCP autoantibody, antibodies to human beta4 and alpha6 integrins, and sera from patients with BP showed homogenous, smooth linear binding along the basement membrane zone (BMZ) of the NHC. NHS, antibodies to other integrins, and sera from patients with chronic cicatrizing conjunctivitis from other causes showed no such binding. When NHC was first absorbed with OCP sera and then reacted with anti-beta4 antibodies or vice versa, the intensity of the BMZ binding was dramatically reduced or completely eliminated, indicating that there were autoantibodies in OCP sera specific for the beta4 integrin. BMZ separation developed 48 to 72 hours after addition of total OCP sera, IgG fractions from OCP sera, immunoaffinity-purified autoantibodies from sera of patients with OCP, or anti-beta4 antibodies to the NHC cultures, but not after addition of normal control sera, sera from patients with chronic cicatrizing conjunctivitis from causes other than OCP, or sera from patients with OCP in clinical remission. CONCLUSION: Circulating anti-beta4 integrin antibody may have an important role in the pathogenesis of OCP.     

Analysis of current data on the use of intravenous immunoglobulins in management of pemphigus vulgaris

BACKGROUND: Systemic corticosteroids, with or without the addition of immunosuppressive adjuvant agents, are frequently used in treating patients with pemphigus vulgaris (PV). The severe, catastrophic, and potentially fatal side effects of these agents highlight the need for the development of safe alternatives for PV therapy. Intravenous immunoglobulin (IVIG) therapy has recently been reported to be effective in the treatment of PV. OBJECTIVE: Our purpose was to do a retrospective analysis of the available literature on the use of IVIG in the treatment of PV. We also wished to determine whether the cumulative evidence permits making preliminary conclusions regarding the potential role of IVIG in the overall management of PV. METHODS: A review of the English-language, peer-reviewed literature was conducted for reports on IVIG use in treatment of PV. The available information on 21 patients was used to assess different dimensions of clinical efficacy. RESULTS: A minimum dose of 2 g/kg per cycle given at regular monthly intervals for a minimum of 3 cycles seems be effective in inducing a rapid clinical remission in patients with severe, recalcitrant PV. However, this should not be perceived as a "standard" dose. Tapering and eventual discontinuation of other agents were possible in many patients. Long-term follow-up was not provided to examine the influence of IVIG on the clinical course of disease, its efficacy as monotherapy, and the benefit of using it as maintenance therapy to keep the patient in prolonged clinical remission. In 4 of the 21 patients (19%), use of IVIG was of no clinical benefit. This failure of efficacy was primarily due to inadequate use. IVIG demonstrated beneficial effect in 17 of 21 patients (81%). CONCLUSION: IVIG may be a safe and effective agent in the management of severe, recalcitrant PV. Multicenter controlled studies, using different dose regimens, with lengthy follow-up periods are necessary to clearly define the emerging beneficial role of IVIG.