Mucosal-dominant Pemphigus Vulgaris Research Articles

Unraveling Mechanisms of Autoimmune Skin Blistering: Applying Single-Cell Transcriptomics to Pemphigus B Cells

Unraveling Mechanisms of Autoimmune Skin Blistering: Applying Single-Cell Transcriptomics to Pemphigus B Cells

Autoantibody-Specific Signalling in Pemphigus.

Pemphigus is a severe autoimmune disease impairing barrier functions of epidermis and mucosa. Autoantibodies primarily target the desmosomal adhesion molecules desmoglein (Dsg) 1 and Dsg 3 and induce loss of desmosomal adhesion. Strikingly, autoantibody profiles in pemphigus correlate with clinical phenotypes. Mucosal-dominant pemphigus vulgaris (PV) is characterised by autoantibodies (PV-IgG) against Dsg3 whereas epidermal blistering in PV and pemphigus foliaceus (PF) is associated with autoantibodies against Dsg1. Therapy in pemphigus is evolving towards specific suppression of autoantibody formation and autoantibody depletion. Nevertheless, during the acute phase and relapses of the disease additional treatment options to stabilise desmosomes and thereby rescue keratinocyte adhesion would be beneficial. Therefore, the mechanisms by which autoantibodies interfere with adhesion of desmosomes need to be characterised in detail. Besides direct inhibition of Dsg adhesion, autoantibodies engage signalling pathways interfering with different steps of desmosome turn-over. With this respect, recent data indicate that autoantibodies induce separate signalling responses in keratinocytes via specific signalling complexes organised by Dsg1 and Dsg3 which transfer the signal of autoantibody binding into the cell. This hypothesis may also explain the different clinical pemphigus phenotypes.

Mucosal-dominant pemphigus vulgaris in a 90-year-old woman

A 90-year-old Japanese woman was referred to our department with a 3-month history of painful gingivae that first appeared at age 90 years. She reported difficulty in eating because of...

A new exvivo human oral mucosa model reveals that p38MAPK inhibition is not effective in preventing autoantibody-induced mucosal blistering in pemphigus.

Pemphigus vulgaris (PV) is an autoimmune disease characterized by blister formation in the epidermis and oral mucosa due to loss of keratinocyte cohesion. Autoantibodies present in patients with PV (PV-IgG) are known to primarily target desmoglein (Dsg)1 and Dsg3 in desmosomes. The mucosal-dominant subtype of PV (mdPV) is caused by PV-IgG autoantibodies against the cadherin-type adhesion molecule Dsg3. p38 mitogen-activated protein kinase (p38MAPK) signalling has been characterized as an important pathway downstream of PV-IgG binding and its inhibition is protective in exvivo human skin. However, the role of p38MAPK signalling in mdPV is unknown as no experimental model has been available. To establish a human exvivo oral mucosa culture, and evaluate the p38MAPK dependency of blister formation and of ultrastructural alterations of desmosomes induced by mdPV-IgG. Human labial mucosa was injected with mdPV-IgG as well as AK23, a pathogenic mouse monoclonal Dsg3 antibody, in the presence or absence of p38MAPK inhibitors. Viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis by terminal deoxynucleotidyl transferase dUTP nick-end labelling assay. Blister score was determined following haematoxylin and eosin staining and Dsg3 distribution by immunostaining. Samples were processed for transmission electron microscopy to analyse desmosome ultrastructure. Both AK23 and mdPV-IgG induced blisters and caused reduction in desmosome size and number in labial mucosa. Inhibition of p38MAPK was not effective in preventing these alterations. In contrast with human epidermis, PV-IgG and AK23 induce blisters and desmosome ultrastructural changes in labial mucosa via a mechanism not dependent on p38MAPK. What's already known about this topic? Pemphigus vulgaris IgG (PV-IgG) induces blistering as well as a reduction in desmosome number and size mediated by p38 mitogen-activated protein kinase (p38MAPK) signalling in exvivo human skin. What does this study add? This study establishes a new human exvivo mucosa model to test pathomechanisms mediated by PV-IgG. The study demonstrates that both AK23 and mucosal-dominant PV induce blisters and associated ultrastructural changes in labial mucosa via a mechanism not dependent on p38MAPK signalling. What is the translational message? This study highlights the respective tissue-specific responses of oral mucosa and skin related to PV pathogenesis, similar to the patient situation.

Associations of anti-desmoglein antibodies with clinical phenotypes and disease activity in pemphigus patients and their change patterns

Objective To investigate associations of anti-desmoglein (Dsg1 and Dsg3) antibodies detected by enzyme-linked immunosorbent assay (ELISA) with clinical phenotypes and disease activity in pemphigus patients, and to explore their change patterns. Methods A total of 111 patients with pemphigus were enrolled from Hospital for Skin Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College between January 2015 and January 2018. ELISA was performed to detect serum levels of anti-Dsg1 and anti-Dsg3 antibodies in these patients with different clinical types of pemphigus at different stages, including onset stage, control stage (no new erythema or vesicles occurred in the last 2 or more weeks, and primary lesions began to regress) , maintenance stage (the condition had been stable for ≥ 1 month, and treatment was maintained with a low dose of glucocorticoids [prednisone equivalent of < 15 mg/d]) , and recurrence stage, and the change patterns of serum levels of anti-Dsg1 and anti-Dsg3 antibodies were analyzed. Statistical analysis was carried out with SPSS 22 software by using one-way analysis of variance for the comparison among groups, and least significant difference (LSD) -t test for multiple comparisons. Results At the disease onset stage, control stage, maintenance stage and recurrence stage, 92, 53, 33, and 9 patients respectively completed the detection. Among the 92 patients with initial onset of pemphigus, the positive rates of anti-Dsg1 and anti-Dsg3 antibodies were 100% and 2.77% respectively in 36 patients with pemphigus foliaceus, 20% and 80% respectively in 10 with mucosal-dominant pemphigus vulgaris, and 97.82%, 95.65% respectively in 46 with mucocutaneous pemphigus vulgaris. The serum levels of anti-Dsg1 antibodies in the patients with pemphigus foliaceus significantly differed among the disease onset stage, control stage, maintenance stage and recurrence stage (137.43 ± 77.74, 13.94 ± 14.81, 21.50 ± 58.33, 121.13 ± 86.89 U/ml, respectively) , the serum levels of anti-Dsg3 antibodies in the patients with mucosal-dominant pemphigus vulgaris also significantly differed among the above clinical stages (125.61 ± 94.81, 34.5 ± 16.26, 0.6, 258 U/ml, respectively) , and the serum levels of anti-Dsg1 and anti-Dsg3 antibodies in patients with mucocutaneous pemphigus vulgaris both significantly differed among the above clinical stages (anti-Dsg1 antibody: 115.39 ± 70.62, 15.74 ± 25.10, 3.62 ± 12.09, 78.60 ± 92.25 U/ml, respectively; anti-Dsg3 antibody: 137.98 ± 81.25, 58.14 ± 63.46, 29.26 ± 64.70, 136.9 ± 101.47 U/ml, respectively) . Additionally, the serum levels of anti-Dsg1 antibodies in the patients with pemphigus foliaceus, as well as the serum levels of anti-Dsg3 antibodies in the patients with mucosal-dominant pemphigus vulgaris and those with mucocutaneous pemphigus vulgaris, were both significantly lower at the disease control stage and maintenance stage than at the disease onset stage and recurrence stage (all P < 0.05) . During the treatment, epitope spreading occurred in 2 patients, and high-titer anti-Dsg antibodies were observed in 4 patients at the stable stage. Conclusion Anti-Dsg antibody spectrum is associated with clinical phenotypes of pemphigus, and its serum levels measured by ELISA can be applied to disease activity monitoring and evaluation of therapeutic efficacy. Key words: Pemphigus; Desmoglein 1; Desmoglein 3; Clinical phenotype; Disease activity

Inhibition of p38MAPK signalling prevents epidermal blistering and alterations of desmosome structure induced by pemphigus autoantibodies in human epidermis.

Pemphigus vulgaris (PV) is a skin blistering disease caused by autoantibodies targeting the desmosomal adhesion proteins desmoglein (Dsg) 3 and 1. The mechanisms underlying pemphigus skin blistering are not fully elucidated but p38 mitogen-activated protein kinase (p38MAPK) activation is one of the signalling events necessary for full loss of cell cohesion. However, it is unclear whether ultrastructural hallmarks of desmosome morphology as observed in patients' lesions are mediated by p38MAPK signalling. In this study, we tested the relevance of p38MAPK for blister formation and the ultrastructural changes induced by PV autoantibodies in human skin. Human skin samples were injected with IgG fractions of one patient suffering from mucocutaneous PV (mcPV-IgG), one from mucosal-dominant PV (mdPV-IgG) or AK23, a pathogenic monoclonal Dsg3 antibody derived from a pemphigus mouse model. Samples were processed for histological and electron microscopy analyses. mcPV-IgG and AK23 but not mdPV-IgG reduced desmosome size, caused interdesmosomal widening and formation of split desmosomes, and altered keratin filament insertion. In contrast, full epidermal blister formation and lower desmosome number were evident in tissue samples exposed to mcPV-IgG only. Pharmacological inhibition of p38MAPK blunted the reduction of desmosome number and size, ameliorated interdesmosomal widening and loss of keratin insertion and prevented mcPV-IgG-induced blister formation. Our data demonstrate that blistering can be prevented by inhibition of p38MAPK in the human epidermis. Moreover, typical morphological alterations induced by mcPV-IgG such as interdesmosomal widening and the reduction of desmosome size at least in part require p38MAPK signalling.

Mucosal-dominant pemphigus vulgaris in a captopril-taking woman with angioedema

We describe a 39-year-old woman with an apparent captopril-induced, contact mucosal-dominant pemphigus vulgaris and angioedema, who took captopril during a bout of arterial hypertension. This exposure suggests that captopril and pathophysiology of angioedema stimulated the development of pemphigus vulgaris, which was diagnosed using the novel, indirect immunofluorescence BIOCHIP mosaic, with the modification to detect serum IgG4 autoantibodies. We discuss the patient, who experienced a chain of events leading to the active stage of pemphigus vulgaris, and review concepts of pemphigus vulgaris inducible by drugs and pathological immunity.

IgG against extracellular subdomains of desmoglein 3 relates to clinical phenotype of pemphigus vulgaris

Pemphigus vulgaris (PV) is associated with autoantibodies against desmoglein (Dsg) 3 inducing epidermal loss of adhesion. The major pathogenic epitopes of Dsg3 are presumably dependent of their conformation. The aim of this study was to characterize the IgG reactivity of sera from a cohort of clinically well-characterized PV patients against presumably non-conformational subdomains of the Dsg3 ectodomain including recently described NH2-terminal immunodominant epitopes. By ELISA, IgG reactivity against distinct subdomains of Dsg3 was related to disease activity and the clinical phenotype of PV patients. Our findings suggest that (i) autoantibody from PV sera react with non-conformational epitopes of Dsg3; (ii) IgG reactivity against the NH2-terminus and the extracellular domains (EC) 2-4 of Dsg3 was associated with active PV, while IgG titres were not strictly correlated with disease activity and (iii) IgG reactivity against the EC1-4 was associated with mucosal dominant PV and was decreased in cutaneous dominant PV. The findings may help to define more refined serological disease markers of PV.

A comparison of anti‐desmoglein antibodies and indirect immunofluorescence in the serodiagnosis of pemphigus vulgaris

Indirect immunofluorescence (IIF) is the standard method for the detection of pemphigus autoantibodies. Commercially available enzyme-linked immunosorbent assays (ELISAs) have recently become available to measure serum antibodies (Abs) against desmoglein1 (Dsg1) and desmoglein3 (Dsg3). It has been suggested that patients with mucosal-dominant pemphigus vulgaris (PV) have serum Abs against Dsg3 only, patients with mucocutaneous PV have Abs to both Dsg1 and Dsg3, and patients with pemphigus foliaceus (PF) have Abs against Dsg1 only. To compare the sensitivity and specificity of the IIF and ELISA tests in the diagnosis of pemphigus and its subsets. Thirty-three patients with PV and five patients with PF were studied, and compared with 50 healthy individuals or patients with unrelated skin diseases. Monkey esophagus was used as a substrate for the IIF test. The IIF and ELISA tests were each positive in 26 of the 32 (81%) PV patients, and in none (0%) and 3 (6%) of the 50 controls, respectively. Both the IIF and ELISA results were concordant in 69% of the PV patients, and only one of these two tests was positive in the remaining 31% of patients. Forty-six per cent of the PV patients with a positive ELISA test did not have the PV phenotype (mucosal or mucocutaneous) predicted by their autoantibody profile. The IIF and ELISA tests may be used as complementary tests for the serologic diagnosis of pemphigus.

Isoform-Specific Differences in the Size of Desmosomal Cadherin/Catenin Complexes

Isoform-Specific Differences in the Size of Desmosomal Cadherin/Catenin Complexes

The clinical phenotype of pemphigus is defined by the anti-desmoglein autoantibody profile

Background: Some patients with pemphigus vulgaris (PV) have mucous membrane erosions with minimal skin involvement (mucosal dominant type), and others show extensive skin blisters and erosions in addition to mucous membrane involvement (mucocutaneous type). Patients with pemphigus foliaceus (PF) show only skin involvement. Objective: The purpose of this study is to determine whether there is a difference in autoantibody profile among mucosal dominant PV, mucocutaneous PV, and PF. Methods: Antibody titer against desmoglein 1 (Dsg1) and desmoglein 3 (Dsg3) were measured with enzyme-linked immunosorbent assay using recombinant Dsg1 and Dsg3. Sera were obtained during clinically active disease from 24 patients with mucosal dominant PV, 20 with mucocutaneous PV, and 23 with PF. Results: All sera samples from patients with mucosal dominant PV sera were negative against Dsg1 but positive against Dsg3. All sera samples from those with mucocutaneous PV were positive against both Dsg1 and Dsg3. All sera samples from patients with PF were positive against Dsg1, but negative against Dsg3. Conclusion: Each subtype has its own anti-Dsg autoantibody profile, indicating that the clinical phenotype of pemphigus is defined by the autoantibody profile. (J Am Acad Dermatol 1999;40:167-70.)