Five Japanese cases of antidesmoglein 1 antibody‐positive and antidesmoglein 3 antibody‐negative pemphigus with oral lesions

Classification and Antigen Molecules of Autoimmune Bullous Diseases

Autoimmune bullous diseases (AIBDs), which are a group of tissue-specific autoimmune diseases of the skin, present with various blistering lesions on the skin and mucous membranes, and show autoantibodies of IgG, IgA and IgM against epidermal cell surfaces and basement membrane zone. To date, AIBDs have been classified into a number of distinct subtypes by clinical and histopathological findings, and immunological characteristics. In addition, various biochemical and molecular biological studies have identified various novel autoantigens in AIBDs, which has resulted in proposals of new subtypes of AIBDs. In this article, we summarized various distinct AIBDs, and proposed the latest and most comprehensive classification of AIBDs with their autoantigen molecules.

Desmoglein compensation hypothesis fidelity assessment in Pemphigus

The pemphigus group of autoimmune blistering diseases encompasses pemphigus vulgaris (PV) and pemphigus foliaceus (PF). Lesion location in pemphigus has been elegantly postulated by the Desmoglein Compensation Hypothesis (DCH), which references the distribution of desmoglein (Dsg) proteins in the epidermis along with a patient’s autoantibody profile to describe three different lesion phenotypes: PF is characterized by subcorneal lesions in the presence of anti-Dsg1 antibodies only, while lesions in PV are suprabasilar and accompanied by anti-Dsg3 antibodies only in mucosal PV, or both anti-Dsg3 and anti-Dsg1 in the case of mucocutaneous PV. While the validity of this hypothesis has been supported by several studies and is prominently featured in textbooks of dermatology, a number of logical inconsistencies have been noted and exceptions have been published in several small-scale studies. We sought to comprehensively assess the extent to which patient clinical and autoantibody profiles contradict the DCH, and characterize these contradictions in a large sample size of 266 pemphigus patients. Remarkably, we find that roughly half of active PV and PF patients surveyed present with a combination of lesion morphology and anti-Dsg3/1 levels that contradict the DCH, including: patients with a cutaneous only PV presentation, mucocutaneous disease in the absence of either Dsg3, Dsg1, or both, and mucosal disease in the absence of Dsg3 or presence of Dsg1. We also find stark differences in fidelity to the DCH based on ethnicity and HLA-association, with the lowest proportion of adherence in previously understudied populations. These findings underscore the need to expand our understanding of pemphigus morphology beyond the DCH, in particular for populations that have not been a focus in previous investigation.

Histopathology of autoimmune bullous dermatoses: What's new?

Autoimmune bullous dermatoses are characterized by the presence of tissue-bound and often circulating pathogenic autoantibodies targeting structural components of the skin and/or mucous membranes. The diagnostic workup for this heterogeneous group of disorders consists of a multi-step process, of which the light microscopic examination is a crucial component. This review is organized following a classification scheme that is based on two main histopathologic features, namely level of intraepithelial split and composition of the inflammatory infiltrate. Overall, we aim to place emphasis on the histopathologic clues that can assist pathologists in differential diagnosis and review the updates in the literature.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

Pemphigus-The Crux of Clinics, Research, and Treatment during the COVID-19 Pandemic

Pemphigus is a rare autoimmune disease characterised by the production of pathogenic autoantibodies in response to different desmosome proteins. The pathophysiological process leads to the development of blisters and erosions on mucosal and/or skin surfaces. The classical clinical variants of pemphigus are pemphigus vulgaris and pemphigus foliaceus. A diagnostic delay is very common in pemphigus, especially among patients with mucosal involvement. However, in recent years we have witnessed considerably fewer patients with extensive mucocutaneous manifestations, since patients with oral lesions are referred to dermatologists to start the treatment much sooner than they had been previously. Among non-classical variants of pemphigus, unusual cases with discrepancies between autoantibody profiles and clinics challenge the "desmoglein compensation theory". The identification of several other autoantigens that perform a role in the pathogenesis of different variants of pemphigus will progress immunodermatology towards an approach that will determine personalized pemphigus subtypes for each patient. Comorbidities among patients are primarily associated with the prolonged use of corticosteroids and other immunosuppressive agents. The SARS-CoV-2 pandemic raised concerns regarding the immunosuppressive effects of treatment and the risk of a more complicated COVID-19 infection, as well as on the ability to develop an adequate vaccine response.

Acantholysis may precede elevation of circulating anti-desmoglein 3 antibody levels in pemphigus vulgaris presenting with desquamative gingivitis

Pemphigus vulgaris (PV) is an autoimmune, blistering disease that affects the mucosa and skin. The current theory favors the concept that anti-desmoglein (Dsg) 3 autoimmunity is the only pathogenic event needed to induce acantholysis. However, a few cases of active PV in the oral cavity had no detectable anti-Dsg 3 antibody. The aim of this study was to evaluate the differences in clinical and laboratory findings, whether or not the anti-Dsg 3 antibodies were present. This study was based on a retrospective review of 10 PV cases. The evaluation of the circulating autoantibody titers to Dsg 3 was conducted by using enzyme-linked immunosorbent assay (ELISA). An index value of 20 or more was used as the cutoff for a positive reaction. Only five of the 10 PV cases had a positive Dsg 3 ELISA. There were no differences in clinical, cytological, histopathological, and direct immunofluorescence findings, whether or not the anti-Dsg 3 antibodies were present. Of the five patients with a negative reaction at the time of diagnosis, the Dsg 3 ELISA became positive in the follow-up period in three cases. In the remaining two cases, the Dsg 3 ELISA was consistently negative for 18 months. Dsg 3 ELISA was negative early in some PV cases. Therefore, PV acantholysis may precede the elevation of circulating anti-Dsg 3 antibody levels. The diagnosis of PV should be considered based on comprehensive clinical, histopathological, and immunofluorescent criteria.

The Evolving Story of Autoantibodies in Pemphigus Vulgaris: Development of the "Super Compensation Hypothesis"

Emerging data and innovative technologies are re-shaping our understanding of the scope and specificity of the autoimmune response in Pemphigus vulgaris (PV), a prototypical humorally mediated autoimmune skin blistering disorder. Seminal studies identified the desmosomal proteins Desmoglein 3 and 1 (Dsg3 and Dsg1), cadherin family proteins which function to maintain cell adhesion, as the primary targets of pathogenic autoAbs. Consequently, pathogenesis in PV has primarily considered to be the result of anti-Dsg autoAbs alone. However, accumulating data suggesting that anti-Dsg autoAbs by themselves cannot adequately explain the loss of cell-cell adhesion seen in PV, nor account for the disease heterogeneity exhibited across PV patients has spurred the notion that additional autoAb specificities may contribute to disease. To investigate the role of non-Dsg autoAbs in PV, an increasing number of studies have attempted to characterize additional targets of PV autoAbs. The recent advent of protein microarray technology, which allows for the rapid, highly sensitive, and multiplexed assessment of autoAb specificity has facilitated the comprehensive classification of the scope and specificity of the autoAb response in PV. Such detailed deconstruction of the autoimmune response in PV, beyond simply tracking anti-Dsg autoAbs, has provided invaluable new insights concerning disease mechanisms and enhanced disease classification which could directly translate into superior tools for prognostics and clinical management, as well as the development of novel, disease specific treatments.

A Case of Concomitant Pemphigus Foliaceus and Oral Pemphigus Vulgaris

Pemphigus is a chronic autoimmune condition that can affect multiple areas of the body. The two main subtypes of pemphigus are pemphigus vulgaris (PV) and pemphigus foliaceus (PF) which can rarely occur concurrently or even transition from one to the other. The process of transition may be explained by qualitative changes in desmoglein autoantibody profile. We present a rare case of concomitant PF and oral PV and explore the literature on transitions between pemphigus subtypes and whether this case could represent a transition from PF to PV. Furthermore, the realities of multidisciplinary patient management are discussed.

Pemphigus, a pathomechanism of acantholysis

Autoantibodies to the desmosomal proteins desmoglein 1 and 3 cause pemphigus foliaceus and pemphigus vulgaris, which are characterised by keratinocyte dissociation (acantholysis) and intraepidermal blister formation. The passive transfer of pathogenic anti-desmoglein antibodies induces blisters in mice in vivo and the loss of keratinocyte adhesion in vitro. The pathogenetic mechanisms of acantholysis due to anti-desmoglein autoantibodies are not fully understood. However, recent studies have revealed that signalling-dependent and signalling-independent pathways are operative in the loss of cell adhesion. In this review, we focus on the pathomechanism of acantholysis due to autoantibodies to desmogleins and recent therapeutic approaches.

E-cadherin autoantibody profile in patients with pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV) is an autoimmune skin blistering disease. The main targets of autoantibodies are the desmosomal proteins desmoglein (Dsg)3 and Dsg1. Anti-E-cadherin antibody is the second most frequent antibody found in pemphigus foliaceus (fogo selvagem), but the frequency in PV is unknown.

OBJECTIVES

To determine the anti-E-cadherin antibody profile in the two major subtypes of PV: mucosal PV (mPV) and mucocutaneous PV (mcPV).

METHODS

Sera from 80 patients with PV and 80 controls were tested. Patients with PV were subdivided into mPV (n = 18) and mcPV (n = 62). Samples were tested by E-cadherin, Dsg1 and Dsg3 enzyme-linked immunosorbent assays (ELISAs), and immunoprecipitation coupled with Western blotting (IP-WB).

RESULTS

Both mPV and mcPV sera have antibodies against E-cadherin as demonstrated by ELISA and IP-WB. Both subtypes of PV have low levels of anti-E-cadherin antibodies, but significantly higher levels than healthy controls by ELISA (P < 0·0001). No difference exists in antibody levels between subgroups (P = 0·82). By IP-WB, 78% of mcPV sera reacted to E-cadherin, vs. 33% of mPV sera tested. Correlation analysis suggests a moderate correlation between anti-E-cadherin antibodies and Dsg1 antibodies (average r = 0·61), but no correlation with Dsg3 antibodies (average r = 0·19). Patients with mPV can have lower levels of Dsg1 antibodies compared with controls by ELISA (P < 0·0001). A few mPV sera also reacted to Dsg1 protein by IP-WB (17%).

CONCLUSIONS

Anti-E-cadherin antibodies are present in both major subtypes of PV. A moderate correlation exists between E-cadherin and Dsg1 antibodies. Patients with mPV can have low levels of both E-cadherin and Dsg1 antibodies.