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M Amagai

Publications and source records attributed to M Amagai.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Clinical aspects and immunopathology in 48 patients with pemphigus].

BACKGROUND AND OBJECTIVE: Pemphigus is a rare intraepidermal autoimmune bullous disease. Two major variants, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), are distinguished. The aim of this study was to document the clinical and immunopathological findings in all pemphigus patients who were diagnosed in the Department of Dermatology at the University of Würzburg over the past 10 years. PATIENTS/METHODS: Based on a retrospective study, clinical and immunopathological findings in 48 patients with pemphigus were recorded. All patients had positive findings by direct and/or indirect immunofluorescence microscopy. RESULTS: Between January 1989 and August 1998, 48 patients were diagnosed with pemphigus at our institution; 31 patients had PV and 17 PF. The average age (+/- standard deviation) of PV patients was 55 (+/- 17) and of PF patients 60 (+/- 12) years. All PV patients showed involvement of mucous membranes and in 65% of cases, the skin was also involved. In contrast, PF patients had involvement only of the skin. By direct immunofluorescence microscopy, intercellular deposits of IgG and C3 were detected in 89% and 78% of PV cases, respectively. In PF, intercellular deposits of IgG were found in 94% and of C3 in 75% of cases. By indirect immunofluorescence microscopy on monkey esophagus, 94% of the PV and 88% of the PF patients revealed circulating serum antibodies. In 30 patients, we characterized the immune response by ELISA using recombinant desmoglein 1 and 3. All PF sera showed autoantibodies against desmoglein 1 and all PV sera against desmoglein 3. In PV with both mucous membrane and skin involvement, antibodies to both desmoglein 3 and 1 were detected. CONCLUSIONS: Our results confirm the correlation of the autoantibody profile with the clinical phenotype of pemphigus.

Adult↗
PubMed2000

Development of pemphigus vulgaris in a patient with pemphigus foliaceus: antidesmoglein antibody profile shift confirmed by enzyme-linked immunosorbent assay.

We describe a patient with pemphigus foliaceus (PF) in whom pemphigus vulgaris (PV) subsequently developed. The clinical change was accompanied by a shift of autoantibody profile confirmed by enzyme-linked immunosorbent assay. Antidesmoglein (Dsg) 1 antibodies alone were detected in the PF stage, whereas both anti-Dsg3 and anti-Dsg1 antibodies were detected in the PV stage.

Adult↗
PubMed2000

Production of the entire extracellular domain of BP180 (type XVII collagen) by baculovirus expression.

Bullous pemphigoid (BP) is an acquired autoimmune skin disease, and its target antigens are a 230 kDa plaque protein (BP230) and a 180 kDa transmembrane protein with interrupted collagenous domains (BP180, type XVII collagen), which localize at the hemidesmosome. In this study we have attempted to express the entire extracellular domain of BP180 (rBP180EC) as a secreted protein by baculovirus expression. Seventy out of 83 BP sera (84.4%) showed positive reactivity against rBP180EC by immunoblot analysis, and 56 out of 83 BP sera (67.5%) were positive against rBP180EC by ELISA. These figures were comparable with those when a bacterial recombinant protein encoding the NC16a domain of BP180 (rNC16a) was used as an antigen source. Reactivity of BP sera against rBP180EC by ELISA was completely abolished or significantly reduced by immunocompetition with rNC16a in 11 out of 14 BP sera tested, while the reactivity was not altered in the rest of the three sera. These findings indicate that the NC16a domain represents the major epitopes on the extracellular domain of BP180, although there are some other minor epitopes outside of NC16a which are uniquely expressed by rBP180EC. rBP180EC will be useful to develop a diagnostic tool for BP as well as to dissect a molecular role for BP180 in interactions of keratinocytes with epidermal basement membrane.

Autoantigens↗
PubMed2000

Identification of desmoglein 1 as autoantigen in a patient with intraepidermal neutrophilic IgA dermatosis type of IgA pemphigus.

In a 51-year-old female patient with intraepidermal neutrophilic IgA dermatosis (IEN) type of IgA pemphigus, circulating IgA, but not IgG, autoantibodies were detected to bind to the cell surface of the whole epidermis, being much stronger in the upper epidermis. In the patient's skin a heavy intraepidermal IgA staining was observed throughout the whole epidermis, accompanied by a weak IgG and a more prominent C3 staining. IgA from the patient's serum showed no reactivity either with epidermal proteins by immunoblot analysis, or with COS 7 cells transiently transfected with mammalian cell expression constructs containing full length human Dsc1, Dsc2 and Dsc3. Our patient's IgA specifically reacted with conformational epitopes of human desmoglein (Dsg) 1 but not Dsg 3, when studied in a previously established, here for IgA antibody detection modified enzyme-linked immunoabsorbent assay (ELISA) of baculovirus expression system. The immunoreactivity against keratinocyte cell surface was completely removed from the serum of the patient by pre-incubation with recombinant Dsg1 baculoprotein. This finding indicates that the sera possess only IgA antibodies against the extracellular domain of Dsg1 baculoprotein, but no antibodies against components of keratinocyte cell surface other than Dsg1. This is the first case of IgA pemphigus where Dsg1 has been identified as the autoantigen.

Autoantigens↗
PubMed2000

Toxin in bullous impetigo and staphylococcal scalded-skin syndrome targets desmoglein 1.

Exfoliative toxin A, produced by Staphylococcus aureus, causes blisters in bullous impetigo and its more generalized form, staphylococcal scalded-skin syndrome. The toxin shows exquisite specificity in causing loss of cell adhesion only in the superficial epidermis. Although exfoliative toxin A has the structure of a serine protease, a target protein has not been identified. Desmoglein (Dsg) 1, a desmosomal cadherin that mediates cell-cell adhesion, may be the target of exfoliative toxin A, because it is the target of autoantibodies in pemphigus foliaceus, in which blisters form with identical tissue specificity and histology. We show here that exfoliative toxin A cleaved mouse and human Dsg1, but not closely related cadherins such as Dsg3. We demonstrate this specific cleavage in cell culture, in neonatal mouse skin and with recombinant Dsg1, and conclude that Dsg1 is the specific receptor for exfoliative toxin A cleavage. This unique proteolytic attack on the desmosome causes a blister just below the stratum corneum, which forms the epidermal barrier, presumably allowing the bacteria in bullous impetigo to proliferate and spread beneath this barrier.

Animals↗
PubMed2000

Pemphigoid nodularis with IgA autoantibodies against the intracellular domain of desmoglein 1.

Pemphigoid nodularis is a rare variant of bullous pemphigoid. We report a 49-year-old Japanese male with clinical and histopathological features of pemphigoid nodularis including circulating and in vivo-bound IgG antibasement membrane zone antibodies and IgA anti-intercellular antibodies. Although the precise molecular target of the IgG autoantibodies could not be determined, intriguingly, immunoblotting showed that the IgA in the patient's serum reacted with the intracellular domain of desmoglein 1, the target antigen in cases of pemphigus foliaceus. However, the IgA did not react with the extracellular domain of desmoglein 1 in sensitive enzyme-linked immunosorbent assay studies using a baculovirus system. These results suggest therefore that these IgA antibodies may possibly not be pathogenic. The mechanism for the production of different autoantibodies is unknown, but this case provides further illustration of the atypical skin immunoreactants often seen in this unusual subtype of bullous pemphigoid.

Anti-Inflammatory Agents↗
PubMed2000

Development of chimeric molecules for recognition and targeting of antigen-specific B cells in pemphigus vulgaris.

Pemphigus vulgaris (PV) is an autoimmune blistering disease characterized by circulating pathogenic IgG antibodies against desmoglein 3 (Dsg3). The purpose of this study was to develop chimeric molecules for specific recognition and elimination of autoimmune B cells in PV. Mouse hybridoma cell lines producing anti-Dsg3 antibody (5H10, 12A2) were developed as an in vitro model system for targeting B cells. Dsg3-GFP, a baculoprotein containing the entire extracellular domain of Dsg3 fused with green fluorescence protein, recognized and targeted the hybridoma cells through their surface immunoglobulin receptors in an antigen-specific way. The epitopes of these monoclonal antibodies were mapped on the amino terminal EC1 and part of EC2, a region considered functionally important in cadherins. Chimeric toxin molecules containing the mapped region (Dsg3deltaN1) and modified Pseudomonas exotoxin were produced in bacteria (Dsg3deltaN1-PE40-KDEL, PE3 7-Dsg3deltaN1-KDEL) and tested in vitro on hybridoma cell lines. The chimeric toxins, but not Dsg3deltaN1 alone, showed dose-dependent toxic activity with a reduction in hybridoma cell number to 40-60% of toxin-negative control cultures, compared with little or no effect on anti-Dsg3-negative hybridoma cells. Furthermore, these toxins showed toxic effects on anti-Dsg3 IgG-producing B cells from Dsg3deltaN1-immunized mice, with a 60% reduction in cell number compared with Dsg3deltaN1 alone. Thus, specific recognition and targeting of antigen-specific B cells in PV was demonstrated; this strategy may hold promise as a future therapeutic option for PV and other autoimmune diseases.

ADP Ribose Transferases↗
PubMed2000

Coexistence of psoriasis and linear IgA bullous dermatosis.

Linear IgA bullous dermatosis (LABD) is characterized by IgA autoantibodies against components of the basement membrane zone (BMZ). A 97-kDa protein is one of the major autoantigens associated with this disease. We report a 68-year-old man who developed LABD after a 3-year history of psoriasis and in the context of active hepatitis C virus infection. He had been treated with cyclosporin for psoriasis for about 9 months. Histologically, there was a subepidermal blister containing neutrophils and eosinophils with lymphocytes infiltrating predominantly in the dermis. Direct immunofluorescent staining showed linear IgA deposition at the BMZ. The patient's IgA autoantibodies bound exclusively to the epidermal side of 1 mol/L salt-split normal human skin. Immunoblot analysis identified a 97-kDa autoantigen in epidermal extracts. This appears to be the first case of LABD with IgA autoantibodies against a 97-kDa autoantigen, associated with psoriasis and hepatitis C virus infection.

Aged↗
PubMed2000

Dissociation of intra- and extracellular domains of desmosomal cadherins and E-cadherin in Hailey-Hailey disease and Darier's disease.

In order to clarify the pathomechanism of acantholysis in Hailey-Hailey disease (HHD) and Darier's disease (DD), the distribution of desmosomal and adherens junction-associated proteins was studied in the skin of patients with HHD (n = 4) and DD (n = 3). Domain-specific antibodies were used to determine the cellular localization of the desmosomal transmembrane glycoproteins (desmogleins 1 and 3 and desmocollin), desmosomal plaque proteins (desmoplakin, plakophilin and plakoglobin) and adherens junction-associated proteins (E-cadherin, alpha-catenin, beta-catenin and actin). A significant difference in staining patterns between intra- and extracellular domains of desmosomal cadherins and E-cadherin was demonstrated in acantholytic cells in both HHD and DD, but not in those in pemphigus vulgaris and pemphigus foliaceus samples used as controls. In acantholytic cells in HHD and DD, antibodies against attachment plaque proteins and intracellular epitopes of desmosomal cadherins exhibited diffuse cytoplasmic staining, whereas markedly reduced staining was observed with antibodies against extracellular epitopes of the desmogleins. Similarly, membrane staining of an intracellular epitope of E-cadherin was preserved, while immunoreactivity of an extracellular epitope of E-cadherin was destroyed. While the DD gene has been identified as ATP2A2, the gene for HHD has not been clarified. The dissociation of intra- and extracellular domains of desmosomal cadherin and E-cadherin is characteristic of the acantholytic cells in HHD and DD, and not of pemphigus. This common phenomenon in HHD and DD might be closely related to the pathophysiological mechanisms in both conditions.

Acantholysis↗
PubMed2000

Induction of keratinocyte IL-8 expression and secretion by IgG autoantibodies as a novel mechanism of epidermal neutrophil recruitment in a pemphigus variant.

A subset of pemphigus herpetiformis, a rare pemphigus variant, is characterized histopathologically by subcorneal acantholysis and neutrophilic infiltration. The mechanism of neutrophil infiltration is unknown, but chemokines such as IL-8 may play a role. We investigated the possible role of IL-8 in two such cases. Direct and indirect immunofluorescence studies demonstrated in vivo-bound and circulating IgG epithelial cell surface-binding autoantibodies, both predominated by IgG4 subclass. ELISA and immunoblotting studies revealed that the patients' IgG autoantibodies recognized recombinant desmoglein 1 but not desmoglein 3. Preadsorption of the patients' sera with recombinant desmoglein 1 completely removed the epidermal cell surface immunostaining. Significantly, immunohistochemistry demonstrated intense expression of IL-8, co-localized with in vivo-bound IgG, in the upper epidermis, where the acantholysis took place. Affinity-purified sera IgG from these two patients, a normal individual, and a pemphigus vulgaris patient containing desmoglein 1 autoantibodies, were incubated with normal human keratinocytes in vitro. Cells treated with these patients' IgG secreted a seven-to-nine-fold increase of IL-8 (30-37 pg/ml) compared with the controls (2-4 pg/ml) and expressed a higher intensity of cytoplasmic IL-8 staining. These data demonstrate a novel functional role for IL-8 in the pathogenesis of the neutrophil-dominant subset of pemphigus herpetiformis. The autoantibody-induced epidermal cell IL-8 expression may represent a novel mechanism of epidermal neutrophil recruitment.

Adult↗
PubMed2000

Use of domain-swapped molecules for conformational epitope mapping of desmoglein 3 in pemphigus vulgaris.

Pemphigus vulgaris is an autoimmune blistering disease caused by autoantibodies against desmoglein 3, a member of the desmosomal cadherin family. These autoantibodies recognize conformation-dependent epitopes on desmoglein 3. In this study we attempted to map the conformational epitopes of desmoglein 3 in pemphigus vulgaris using recombinant desmoglein 3 produced by the baculovirus expression system. We developed a series of domain-swapped molecules between desmoglein 3 and desmoglein 1, which have similar structures but distinct epitopes. These were developed by substituting deleted segmental regions of desmoglein 3 by the corresponding desmoglein 1. Thus domain-swapped molecules containing desmoglein 3 residues 1-403, 1-161, 163-566, and 405-566 were constructed and used as competitors for competition enzyme-linked immunosorbent assay against the entire extracellular domain of desmoglein 3 with 25 pemphigus vulgaris sera. Considering more than 50% absorption as significant, residues 1-403 and 1-161 showed significant absorption in 24 out of 25 (96%) and 18 out of 25 (72%) pemphigus vulgaris sera, respectively, whereas only one serum and no sera showed significant absorption by residues 163-566 and 405-566, respectively. Furthermore, no apparent change in their major epitopes was seen during the time course in four pemphigus vulgaris cases tested. These findings indicate that the domain-swapping approach is useful for conformational epitope mapping in pemphigus and that amino-terminal residues 1-161, which are considered to include a region essential for cell-cell adhesion in cadherins, contain the critical residues of the conformational epitope of desmoglein 3 recognized by the autoantibodies in pemphigus vulgaris sera.

Autoantigens↗
PubMed2000

Detection of antigen-specific B cells in patients with pemphigus vulgaris by enzyme-linked immunospot assay: requirement of T cell collaboration for autoantibody production.

Patients with pemphigus vulgaris have circulating IgG autoantibodies against desmoglein 3, which inhibit cell-cell adhesion of keratinocytes and cause blister formation in the skin and mucous membrane. To examine cellular mechanisms underlying the autoantibody production in pemphigus vulgaris patients, we have successfully developed an enzyme-linked immunospot assay which was able to detect desmoglein 3-specific autoimmune B cells quantitatively. Circulating B cells producing anti-desmoglein 3 antibodies were detected exclusively in three patients with severe disease (1.3-2.3/105 peripheral blood mononuclear cells), but not in 10 patients with mild disease or in remission or in seven healthy individuals. When this enzyme-linked immunospot assay was combined with in vitro stimulation of peripheral blood mononuclear cells with pokeweed mitogen and recombinant-desmoglein 3, we could detect circulating desmoglein 3-specific memory B cells in nine of 14 patients (6.3-84. 0/105 peripheral blood mononuclear cells), but in none of 10 healthy individuals. We further analyzed the role of CD4 + T cells in promoting anti-desmoglein 3 antibody production. The in vitro anti-desmoglein 3 antibody production was abolished when CD4 + cells were depleted or when anti-HLA-DR or anti-HLA-DQ monoclonal antibody was added to the cultures. Our results demonstrated the quantitative detection of circulating "activated" and "memory" desmoglein 3-specific B cells and suggested the important part of HLA class II-restricted CD4 + T cells in the autoantibody production in pemphigus vulgaris. In addition, the enzyme-linked immunospot assay in combination with in vitro stimulation of B cells could be broadly applied to study mechanisms for autoantibody production in various autoimmune diseases.

Adult↗
PubMed2000

C-Terminus of desmoyokin/AHNAK protein is responsible for its translocation between the nucleus and cytoplasm.

We previously demonstrated that desmoyokin gene is identical to AHNAK gene, which is downregulated in neuroblastomas. Whereas desmoyokin/AHNAK protein is distributed in the nucleus and cytoplasm in nonepithelial tissues, it is distributed in the cell membrane in epithelial tissues. It is present diffusely in the cytoplasm and nucleus of epithelial cell lines cultured in low calcium condition. Low to normal calcium shift translocates it to the cell boundary. In this study, we investigated which domain(s) of desmoyokin/AHNAK protein are responsible for its different distribution. We constructed three different eukaryotic expression plasmids, pN-DY, pM-DY, and pC-DY, which expressed N-terminus, central domain, and C-terminus of this molecule, respectively, when transfected into COS-7 cells, normal human keratinocytes, and HeLa cells. In normal calcium medium, whereas N-terminus and central domain of desmoyokin/AHNAK protein were present mainly in the cytoplasm, C-terminus was present in the nucleus, cytoplasm, and weakly in the cell membrane. In low calcium medium, C-terminus was present exclusively in the nucleus, and a part of the molecules translocated from the nucleus to the cytoplasm, 3 h after the shift to normal calcium medium or 3 h after addition of protein kinase C activator, 12-O-tetradecanoylphorbol-13-acetate in low calcium medium. Calcium shift showed no effects on the distribution of N-terminus and central domain. These results suggested that C-terminus, but neither N-terminus nor central domain, is responsible for the translocation of this protein into the nucleus. This study may also suggest that C-terminus play a role in the translocation to the cell membrane, although further evidence is necessary.

Animals↗
PubMed2000

Rapid response of IgA pemphigus of subcorneal pustular dermatosis type to treatment with isotretinoin.

Diagnosing IgA pemphigus and distinguishing between its 2 subtypes, intraepidermal neutrophilic IgA dermatosis type and subcorneal pustular dermatosis type, is important because treatment of IgA pemphigus has to be different from treatment of other blistering autoimmune dermatoses. We present a patient with subcorneal pustular dermatosis type of IgA pemphigus who rapidly responded to systemic treatment with isotretinoin. Specific diagnosis was established by detecting IgA serum activity to desmocollin 1 by indirect immunofluorescence microscopy on unfixed COS7 cells transfected with desmocollin 1. No IgA or IgG serum reactivity was found to recombinant forms of desmogleins 1 and 3 by an antigen-specific enzyme-linked immunosorbent assay. The disease was not effectively controlled by conventional therapeutic regimens. Systemic treatment with isotretinoin 20 mg daily led to complete clearance of skin lesions within 3 weeks. Assaying IgA serum reactivity to desmocollin 1, desmoglein 1, and desmoglein 3 as a valuable method for establishing the diagnosis and differentiating the 2 subtypes of IgA pemphigus. Isotretinoin was an effective drug in the treatment of subcorneal pustular dermatosis type of IgA pemphigus in this patient.

Aged↗
PubMed2000

Use of autoantigen-knockout mice in developing an active autoimmune disease model for pemphigus.

The development of experimental models of active autoimmune diseases can be difficult due to tolerance of autoantigens, but knockout mice, which fail to acquire tolerance to the defective gene product, provide a useful tool for this purpose. Using knockout mice lacking desmoglein 3 (Dsg3), the target antigen of pemphigus vulgaris (PV), we have generated an active disease model for this autoantibody-mediated disease. Dsg3(-/-) mice, but not Dsg3(+/-) littermates, produced anti-Dsg3 IgG that binds native Dsg3, when immunized with recombinant mouse Dsg3. Splenocytes from the immunized Dsg3(-/-) mice were then adoptively transferred into Rag-2(-/-) immunodeficient mice expressing Dsg3. Anti-Dsg3 IgG was stably produced in the recipient mice for more than 6 months without further boosting. This IgG bound to Dsg3 in vivo and disrupted the cell-cell adhesion of keratinocytes. Consequently, the recipient mice developed erosions in their oral mucous membranes with typical histologic findings of PV. In addition, the recipient mice showed telogen hair loss, as found in Dsg3(-/-) mice. Collectively, the recipient mice developed the phenotype of PV due to the pathogenic anti-Dsg3 IgG. This model will be valuable for developing novel therapeutic strategies. Furthermore, our approach can be applied broadly for the development of various autoimmune disease models.

Animals↗
PubMed2000

Different effects of dominant negative mutants of desmocollin and desmoglein on the cell-cell adhesion of keratinocytes.

Desmosomes contain two types of cadherin: desmocollin (Dsc) and desmoglein (Dsg). In this study, we examined the different roles that Dsc and Dsg play in the formation of desmosomes, by using dominant-negative mutants. We constructed recombinant adenoviruses (Ad) containing truncated mutants of E-cadherin, desmocollin 3a, and desmoglein 3 lacking a large part of their extracellular domains (EcaddeltaEC, Dsc3adeltaEC, Dsg3deltaEC), using the Cre-loxP Ad system to circumvent the problem of the toxicity of the mutants to virus-producing cells. When Dsc3adeltaEC Ad-infected HaCaT cells were cultured with high levels of calcium, E-cadherin and beta-catenin, which are marker molecules for the adherens junction, disappeared from the cell-cell contact sites, and cell-cell adhesion was disrupted. This also occurred in the cells infected with EcaddeltaEC Ad. With Dsg3deltaEC Ad infection, keratin insertion at the cell-cell contact sites was inhibited and desmoplakin, a marker of desmosomes, was stained in perinuclear dots while the adherens junctions remained intact. Dsc3adeltaEC Ad inhibited the induction of adherens junctions and the subsequent formation of desmosomes with the calcium shift, while Dsg3deltaEC Ad only inhibited the formation of desmosomes. To further determine whether Dsc3adeltaEC directly affected adherens junctions, mouse fibroblast L cells transfected with E-cadherin (LEC5) were infected with these mutant Ads. Both Dsc3adeltaEC and EcaddeltaEC inhibited the cell-cell adhesion of LEC5 cells, as determined by the cell aggregation assay, while Dsg3deltaEC did not. These results indicate that the dominant negative effects of Dsg3deltaEC were restricted to desmosomes, while those of Dsc3adeltaEC were observed in both desmosomes and adherens junctions. Furthermore, the cytoplasmic domain of Dsc3adeltaEC coprecipitated both plakoglobin and beta-catenin in HaCaT cells. In addition, beta-catenin was found to bind the endogenous Dsc in HaCaT cells. These findings lead us to speculate that Dsc interacts with components of the adherens junctions through beta-catenin, and plays a role in nucleating desmosomes after the adherens junctions have been established.

Animals↗
PubMed2000

Thymoma with pemphigus foliaceus.

A 75-year-old Japanese woman was referred to us because of an anterior mediastinal mass. Crusts and shallow erosions developed 10 months earlier on her upper chest, back, and scalp. Pemphigus foliaceus was diagnosed based on histological examination of skin biopsy specimens and positivity for serum anti-desmoglein 1 antibody by enzyme-linked immunosorbent assay. Neurological examination and electromyography ruled out myasthenia gravis. Total thymectomy was performed, and the postoperative pathology studies showed mixed lymphoepithelial thymoma. One year after the resection, the eruption and alopecia improved and the serum anti-desmoglein 1 antibody titer decreased, suggesting a beneficial effect of thymectomy on thymoma-related pemphigus.

Aged↗