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Biomedical subjects

M Amagai

Publications and source records attributed to M Amagai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Dominant autoimmune epitopes recognized by pemphigus antibodies map to the N-terminal adhesive region of desmogleins.

Desmoglein (Dsg) is a cadherin-type adhesion molecule found in desmosomes. Dsg1 and Dsg3 are the target Ags in the autoimmune blistering diseases pemphigus foliaceus (PF) and pemphigus vulgaris (PV), respectively. To map conformational epitopes of Dsg1 and Dsg3 in PF and PV, we generated Dsg1- and Dsg3-domain-swapped molecules and point-mutated Dsg3 molecules with Dsg1-specific residues by baculovirus expression. The swapped domains were portions of the N-terminal extracellular domains of Dsg1 (1-496) and Dsg3 (1-566), which have similar structures but distinct epitopes. The binding of autoantibodies to the mutant molecules was assessed by competition ELISAs. Domain-swapped molecules containing the N-terminal 161 residues of Dsg1 and Dsg3 yielded >50% competition in 30/43 (69.8%) PF sera and 31/40 (77.5%) PV sera, respectively. Furthermore, removal of Abs against the 161 N-terminal residues of Dsg1 by immunoadsorption eliminated the ability of PF sera to induce cutaneous blisters in neonatal mice. Within these N-terminal regions, most of the epitopes were mapped to residues 26-87 of Dsg1 and 25-88 of Dsg3. Furthermore, a point-mutated Dsg3 molecule containing Dsg1-specific amino acid substitutions (His(25), Cys(28), Ala(29)) reacted with anti-Dsg1 IgG, thus defining one of the epitopes of Dsg1. Using the predicted three-dimensional structure of classic cadherins as a model, these findings suggest that the dominant autoimmune epitopes in both PF and PV are found in the N-terminal adhesive surfaces of Dsgs.

Autoantibodies↗
PubMed2001

Monitoring of methyl jasmonate-responsive genes in Arabidopsis by cDNA macroarray: self-activation of jasmonic acid biosynthesis and crosstalk with other phytohormone signaling pathways.

Jasmonates mediate various physiological events in plant cells such as defense responses, flowering, and senescence through intracellular and intercellular signaling pathways, and the expression of a large number of genes appears to be regulated by jasmonates. In order to obtain information on the regulatory network of jasmonate-responsive genes (JRGs) in Arabidopsis thaliana (Arabidopsis), we screened 2880 cDNA clones for jasmonate responsiveness by a cDNA macroarray procedure. Since many of the JRGs reported so far have been identified in leaf tissues, the cDNA clones used were chosen from a non-redundant EST library that was prepared from above-ground organs. Hybridization to the filters was achieved using alpha-33P-labeled single-strand DNAs synthesized from mRNAs obtained from methyl jasmonate (MeJA)-treated and untreated Arabidopsis seedlings. Data analysis identified 41 JRGs whose mRNA levels were changed by more than three fold in response to MeJA. This was confirmed by Northern blot analysis by using eight representatives. Among the 41 JRGs identified, 5 genes were JA biosynthesis genes and 3 genes were involved in other signaling pathways (ethylene, auxin, and salicylic acid). These results suggest the existence of a positive feedback regulatory system for JA biosynthesis and the possibility of crosstalk between JA signaling and other signaling pathways.

Acetates↗
PubMed2001

Immunoreactivity against intracellular domains of desmogleins in pemphigus.

In pemphigus vulgaris (PV) and pemphigus foliaceus (PF), most of the autoantibodies are directed against the extracellular domains of desmoglein 1 (Dsg1) or Dsg3, and those antibodies are proved to play a pathogenic role in blister formation in the skin and mucous membranes. However, some pemphigus sera have been reported to react with the intracellular domains of these antigens. In the present study, we examined the reactivity of the sera from various types of pemphigus with recombinant proteins of extracellular and intracellular domains of human Dsg1 and Dsg3 by immunoblot analysis. We produced the entire extracellular domain of Dsg1 or Dsg3 fused with mouse IgG2a by baculovirus expression. We prepared the intracellular domain of Dsg1 or Dsg3 fused with glutathione-S-transferase by bacterial expression. All of the 31 PV sera reacted with the extracellular domain of Dsg3 and four reacted with the intracellular domain. Six out of 19 PF sera reacted with the extracellular domain of Dsg1 and five reacted with the intracellular domain. In addition, some sera of Brazilian PF patients or cases with mixed features of PV and PF also reacted with the intracellular domains of Dsg1 or Dsg3. Although the frequency was low, some sera did react with the intracellular domain of Dsgs.

Baculoviridae↗
PubMed2001

Predominant IgG4 subclass in autoantibodies of pemphigus vulgaris and foliaceus.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune skin diseases caused by autoantibodies against desmoglein (Dsg) 3 and Dsg1. We have previously developed ELISAs using recombinant Dsg3 and Dsg1 expressed by baculovirus as a diagnostic tool for pemphigus. In this study, we determined the frequency of coexistence of IgA class as well as distribution of IgG subclass. Two out of 49 PV and PF sera tested had anti-Dsg1 IgA in addition to anti-Dsg1 IgG. Interestingly, one of them showed prominent pustular formation. Among IgG subclass, IgG4 was predominant and found in all of the 30 PV and 19 PF sera tested, followed by IgG1, detected in 25 out of 30 PV and 12 out of 19 PF sera. Even though IgG2 and IgG3 were detected in 13 and one PV and 6 and 4 PF sera, respectively, the ELISA titers had barely exceeded the cutoff value in most of the cases. There was no IgG subclass shift during the course of the disease in seven cases examined. These findings indicate that IgG4 subclass is the predominant autoantibodies in both PV and PF, while IgG1 is also frequently found.

Antibody Specificity↗
PubMed2001

The clinical transition between pemphigus foliaceus and pemphigus vulgaris correlates well with the changes in autoantibody profile assessed by an enzyme-linked immunosorbent assay.

BACKGROUND: There are a number of reports of pemphigus with clinical shifting between pemphigus foliaceus (PF) and pemphigus vulgaris (PV). On the other hand, a novel enzyme-linked immunosorbent assay (ELISA) against recombinant baculoproteins of desmoglein 1 (Dsg1) (PF antigen) and Dsg3 (PV antigen) has been established and found to be extremely sensitive and specific. OBJECTIVES: To characterize the change in the antibody profiles in a series of pemphigus cases with mixed features of PF and PV by various methods, including the novel ELISA. Patients/methods Sera were obtained from eight cases undergoing a shift between PF and PV and three cases of coexistent PF and PV. The autoantigens were analysed by ELISA, as well as by immunofluorescence using normal human skin sections and immunoblotting using normal human epidermal extracts. RESULTS: The results of the ELISA, immunofluorescence and immunoblotting studies showed that the transition between PF and PV correlates well with the changes of autoantibodies against either Dsg1 or Dsg3. CONCLUSIONS: The clinical phenotype at each stage is defined by the anti-Dsg antibody profile in the serum of these pemphigus patients showing mixed features of PF and PV. In addition, ELISA using recombinant baculoproteins was particularly useful in distinguishing PF and PV.

Adult↗
PubMed2001

Paraneoplastic pemphigus: an association with fludarabine?

Paraneoplastic pemphigus is a relatively recently described immunobullous disease with characteristic features. We report three cases of paraneoplastic pemphigus in adult men with chronic lymphocytic leukaemia arising within a week of completion of treatment with fludarabine. In all cases, withdrawal of fludarabine and treatment of the blistering was associated with marked cutaneous improvement. Fludarabine, a synthetic nucleoside analogue, which has only been available in Britain since 1994, is known to be associated with autoimmune phenomena and may have been involved in the development of paraneoplastic pemphigus in these cases.

Antineoplastic Agents↗
PubMed2001

Pemphigus foliaceus with prominent neutrophilic pustules.

We describe four patients with generalized scaly and pustular skin lesions showing extensive neutrophilic infiltration in the subcorneal region of the epidermis. Immunofluorescence, immunoblot and enzyme-linked immunosorbent assay analyses detected IgG antibodies reacting exclusively with desmoglein 1, the pemphigus foliaceus antigen. This study indicates that pemphigus foliaceus may show prominent neutrophilic pustular skin lesions.

Adult↗
PubMed2001

Eosinophilic pustular folliculitis (Ofuji's disease): indomethacin as a first choice of treatment.

Eosinophilic pustular folliculitis (EPF) is characterized by erythematous patches of large follicular papules and pustules involving mainly the face. Although various treatments have been attempted for EPF, including systemic and topical steroid, diaphenylsulphone, colchicine, minocycline as well as UVB phototherapy, there is no consensus on the first choice of treatment. We report a typical case and summarize 25 patients with EPF treated in our hospital between 1978 and 1998. Indomethacin was most frequently used (12/25) and showed clinical improvement in the majority of the cases (11/12). The effect of indomethacin was usually observed within 1--2 weeks after initiation of treatment. Decrease of peripheral blood eosinophils accompanied the clinical improvement. Thus, indomethacin should be considered as a first choice of treatment for EPF.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Clinical phenotype and anti-desmoglein autoantibody profile in paraneoplastic pemphigus.

BACKGROUND: Paraneoplastic pemphigus (PNP) has similar features to pemphigus vulgaris (PV), including circulating anti-desmoglein (Dsg) IgG as pathogenic autoantibodies. When PV is divided into mucosal dominant type and mucocutaneous type, mucosal dominant type has only anti-Dsg3 IgG, whereas the mucocutaneous type has both anti-Dsg3 and anti-Dsg1 IgG. OBJECTIVE: The purpose of this study was to determine whether there is a difference in anti-Dsg autoantibody profile between mucosal dominant PNP and mucocutaneous PNP. METHODS: Twenty-one patients with PNP were categorized as mucosal dominant and mucocutaneous types based on clinical information. Antibody titers against Dsg3 and Dsg1 were measured by enzyme-linked immunosorbent assay by means of recombinant Dsg1 and Dsg3. RESULTS: There were 9 cases of mucosal dominant type and 12 cases of mucocutaneous type. Eight of 9 cases of mucosal dominant type were positive for anti-Dsg3 IgG, but 3 of them were also positive for anti-Dsg1 IgG. All 12 cases of mucocutaneous type were positive for anti-Dsg3 IgG, whereas only 6 of them were positive for anti-Dsg1 IgG. CONCLUSION: There was no clear association between the clinical phenotype and anti-Dsg antibody profile in PNP as seen in PV. This finding suggests that besides anti-Dsg IgG other pathologic mechanisms such as lichenoid reaction or interface dermatitis may be involved in the blister formation in PNP.

Adolescent↗
PubMed2001

A Case of pemphigus foliaceus which occurred after five years of remission from pemphigus vulgaris.

A 77-year-old Japanese female developed pemphigus foliaceus (PF) after 5 years of remission from pemphigus vulgaris (PV). The patient had painful erosions in her mouth and flaccid blisters of the skin and was diagnosed as having PV, which responded well to corticosteroid treatment. She was then free from any lesion of PV for 5 years with a low dose of corticosteroid. Then she developed scaly erythematous lesions on the skin and was diagnosed as suffering from PF. Enzyme-linked immunosorbent assay (ELISA) using recombinant desmoglein 1 (Dsg-1) and Dsg-3 revealed that she had anti-Dsg-3 IgG in the PV stage, no antibodies during remission and anti-Dsg-1 IgG in the PF stage. These findings indicate that the target antigen was shifted from Dsg-3 to Dsg-1 along with the phenotype after a 5-year interval in this patient.

Adrenal Cortex Hormones↗
PubMed2001

Detection of IgA autoantibodies to desmogleins by an enzyme-linked immunosorbent assay: the presence of new minor subtypes of IgA pemphigus.

OBJECTIVE: To examine the frequency of antidesmoglein 1 (Dsg1) and antidesmoglein 3 (Dsg3) IgA autoantibodies in IgA pemphigus. DESIGN: We developed an enzyme-linked immunosorbent assay against recombinant Dsg1 and Dsg3 to detect IgA autoantibodies. PATIENTS: Twenty-two patients with IgA pemphigus were studied. Among them, 10 patients had subcorneal pustular dermatosis type, 9 patients had intraepidermal neutrophilic IgA dermatosis type, and 3 patients had pemphigus foliaceus-like clinical features. RESULTS: Of the 22 cases of IgA pemphigus, 3 cases were positive for anti-Dsg1 IgA antibodies and only 1 case was positive for anti-Dsg3 IgA antibodies. In those 4 cases, there were no IgA autoantibodies against other components of the keratinocyte cell surfaces because preincubation with the respective recombinant desmogleins removed the immunoreactivity on immunofluorescence. All 10 patients with subcorneal pustular dermatosis type IgA pemphigus were positive against desmocollin 1 expressed on COS-7 cells. No target antigen was detected in the other 8 cases. CONCLUSIONS: Desmogleins were recognized by IgA antibodies of a few patients with IgA pemphigus. Considering that subcorneal pustular dermatosis type IgA pemphigus recognizes desmocollin 1, autoimmune targets of IgA pemphigus are more heterogeneous than previously considered.

Autoantigens↗
PubMed2001

A case of generalized Hailey-Hailey disease with fatal liver injury.

We report a case of a 59-year-old man with a severe generalized form of Hailey-Hailey disease that was complicated by fatal liver injury. Erosive lesions were first noted in the axillary and perianal regions at 15 year of age, and Hailey-Hailey disease was diagnosed based on the clinical features and histologic findings in skin biopsy specimens. The patient was treated with at first topical steroids and later a low dose of a corticosteroid, but the skin lesions gradually became generalized. At 45 years of age liver dysfunction was detected after azathioprine and vinblastine treatment for the generalized skin lesions. The liver injury gradually progressed and finally the patient died. The gene responsible for Hailey-Hailey disease was recently identified as ATP2C1, and it encodes a Ca(2+)-transport ATPase with broad expression, including in skin and liver. This finding suggests that mutation of the ATP2C1 gene may give rise to an extracutaneous phenotype, such as the liver dysfunction observed in severe cases, including our own. Further accumulation of cases is necessary to determine whether this is true.

Calcium-Transporting ATPases↗