Anti-desmoglein IgG autoantibodies in patients with pemphigus in remission

B-cell targeted therapy of pemphigus

Pemphigus is an autoimmune disease that causes blistering and erosion of the skin and mucous membranes because of autoantibodies against desmoglein, which plays an important role in adhesion between epidermal keratinocytes. Treatment of pemphigus has long been centered on corticosteroids, and the guidelines for management of pemphigus have recommended high-dose systemic corticosteroids as the first-line treatment. While guideline-based treatment has been shown to be beneficial in patients with pemphigus, it has also become clear that this treatment is accompanied by significant burden and risk. The challenge for future pemphigus treatment is to maximize efficacy while minimizing risk during the course of the disease. In this regard, treatment targeting B cells is expected to become increasingly important as autoreactive B cells in pemphigus patients are thought to play a major role in the production of autoantibodies, which form the basis of the pathogenesis. The recent expansion of insurance coverage to rituximab, a monoclonal antibody against CD20, for refractory pemphigus in the USA, Europe, and Japan has opened up a new era of pemphigus treatment by enabling treatment strategies with drugs targeting B cells in patients. Here, we discuss the current status and future prospects of pemphigus treatment, focusing on rituximab and Bruton's tyrosine kinase inhibitors, which are expected to become essential drugs for pemphigus treatment in the future.

Pemphigus patients with initial negative levels of anti- desmoglein; a subtype with different profile?

BACKGROUND

Pemphigus is a blistering autoimmune disease that is characterized by autoantibodies against desmoglins (Dsg), including anti-Dsg1 and anti-Dsg3. Despite the diagnosis of diseases, the anti-Dsg test by Enzyme-linked immunosorbent assay (ELISA) is negative in a small group of pemphigus patients. The aim of this study was to evaluate the clinical course, clinical symptoms, and response to treatment in pemphigus patients with negative levels of anti-Dsg1 and anti-Dsg3.

METHODS

In this study, the data of pemphigus patients referred to Razi Hospital were retrospectively collected from the medical records from 2016 to 2020. Eight patients, whose initial anti-Dsg1/anti-Dsg3 was negative by the ELISA test, were enrolled and their clinical course, clinical signs, and response to treatment were evaluated.

RESULTS

The mean age of the subjects (8 females) was 38.75±12.09. The most common phenotype of the subjects was pemphigus vulgaris (PV) with mucosal involvement. Additionally, the common site of blister inception was mouth of the patients. The mean prednisolone dose received by the patients at the initiation was 32.5±13.62 mg/day. According to Pemphigus Disease Area Index (PDAI), 6 patients had mild severity, wile 2 cases had moderate severity. Among the patients, 6 subjects received rituximab (RTX). Also, 5 patients experienced remission after 6.2±5.21 months.

CONCLUSION

PV is the most common phenotype of the disease and mucosal involvement is more common in patients with negative anti-Dsg-1/3 results. The severity of the lesions in most of the patients is mild at baseline and most patients seems to respond to RTX therapy and reach remission.

Analysis of clinical characteristics, prognosis and antibody pathogenicity of pemphigus patients positive for anti-desmoglein IgG autoantibodies in remission: a retrospective cohort study

BACKGROUND

The detection of serum anti-desmoglein (Dsg) IgG autoantibodies has been reported to be useful for assessment of disease activity in pemphigus. However, previous studies have reported that anti-Dsg autoantibodies remain detectable in some patients without active pemphigus lesions.

OBJECTIVES

To investigate the clinical characteristics and antibody pathogenicity of pemphigus patients positive for anti-Dsg IgG autoantibodies in remission.

METHODS

We retrospectively investigated pemphigus patients with a history of clinical remission who visited the Department of Dermatology of Keio University during 2019 and 2020. The antibody pathogenicity was assessed by bead aggregation assay.

RESULTS

When patients were recognized as having entered remission (PDAI = 0 and PSL ≦ 10 mg/day for 2 months), serum autoantibodies against Dsg were detected in 72 of 132 patients (54.5%, positive group; PG), but were not detected in 60 patients (45.5%, negative group; NG). Anti-Dsg antibody titres in remission declined from the active phase in 33 patients in the PG for whom data were available. There were no differences in the chance of reducing PSL to 5 mg/day (P = 0.885) and rate of relapse (P = 0.279) between PG and NG, but fewer patients in PG discontinued corticosteroids (P = 0.004). The ability of patients' sera to block aggregation of Dsg/desmocollin beads was significantly reduced in remission compared to the active phase. However, our results revealed that whole sera in remission still had pathogenic activity in seven of nine patients, and the approximately equal amounts of anti-Dsg antibodies in active phase and remission showed similar pathogenicity.

CONCLUSIONS

This study will provide guidance in cases where autoantibodies are found to be positive in pemphigus patients during remission or steroid reduction.

Clinical and serological predictors of relapse in pemphigus: a study of 143 patients

BACKGROUND

Pemphigus is an autoimmune bullous disease mediated by autoantibodies targeting epithelial cell-cell adhesion molecules. Predictors of relapse have not yet been clearly identified.

AIMS

To identify factors at diagnosis and during follow-up that could be predictors of relapse.

METHODS

Clinical and immunopathological data at diagnosis, clinical remission and first relapse from patients with pemphigus vulgaris or foliaceus and at least a 36-month follow-up were collected retrospectively. Based on the autoantibody profile at diagnosis, three serological patient subsets were devised: (i) anti-desmoglein (Dsg)1-positive and anti-Dsg3-negative; (iii) anti-Dsg1-negative and anti-Dsg3-positive; and (iii) anti-Dsg1-positive and anti-Dsg3-positive.

RESULTS

Data from 143 patients were collected. No significant differences were found between relapsers (n = 90) and nonrelapsers (n = 53) for time to remission or for anti-Dsg1 and anti-Dsg3 titres at diagnosis and remission. In the analysis of all patients, a higher risk of relapse was found for a body surface area (BSA) score of 3 compared with BSA < 3 (OR = 3.30, 95% CI 1.17-9.28; P = 0.02) and for a positive titre of either anti-Dsg1 or anti-Dsg3 autoantibodies at remission compared with both being negative (OR = 2.42, 95% CI 1.21-4.85, P = 0.01). In patients who were anti-Dsg3-positive and anti-Dsg1-negative at diagnosis, failure to achieve anti-Dsg3 negativity at clinical remission was a significant predictor of relapse (OR = 7.89, 95% CI 2.06-30.21; P < 0.01). Similarly, failure to achieve anti-Dsg1 negativity at clinical remission was a significant predictor of relapse in patients with both anti-Dsg1 and anti-Dsg3 positivity at diagnosis (OR = 5.74, 95% CI 1.15-28.61; P = 0.03), but not in those who were anti-Dsg1-positive/anti-Dsg3-negative at diagnosis (OR = 1.08, 95% CI 0.27-4.30; P = 0.91).

CONCLUSION

Regardless of pemphigus subtype, autoantibody titre negativity at clinical remission in patients classified based on their anti-Dsg1 and anti-Dsg3 profile at diagnosis and BSA were useful tools in predicting relapse.

Hematological Inflammatory Markers in Patients with Pemphigus Vulgaris

BACKGROUND

Emerging evidence indicates that several hematological markers can be used to evaluate treatment response, prediction, and early relapse detection in different inflammatory conditions. This study aimed to investigate the correlation between the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, platelet-to-neutrophil ratio, mean platelet volume, and disease activity in patients with pemphigus vulgaris.

METHODS

Fifty-six patients (20 men, 36 women; mean age 54 ± 14 years) diagnosed with pemphigus vulgaris were included in this retrospective study. Patients were divided into those treated and not treated with rituximab (groups 1 and 2), and into those who did and did not develop relapse (groups 3 and 4). The neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, platelet-to-neutrophil ratio and mean platelet volume were evaluated at the time of diagnosis, remission, and relapse. The relationship between each marker and disease stage was analyzed using the Wilcoxon rank-sum test for pairwise comparisons.

RESULTS

The neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio showed a positive correlation with disease activity, while the platelet-to-neutrophil ratio and mean platelet volume showed a negative correlation. The neutrophil-to-lymphocyte ratio significantly decreased in remission (p < 0.001) and significantly increased in relapse (p < 0.01). The platelet-to-lymphocyte ratio significantly decreased in remission (p < 0.001) and showed no significant change in relapse. The platelet-to-neutrophil ratio significantly increased in remission (p < 0.001) and significantly decreased at relapse (p < 0.001). The mean platelet volume significantly increased in remission (p < 0.001) and decreased non-significantly at relapse. A more significant decrease in the neutrophil-to-lymphocyte ratio in remission was found in patients not treated with rituximab. No significant differences were observed between patients who developed relapse and those who did not.

CONCLUSION

Our results suggest that the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, platelet-to-neutrophil ratio, and mean platelet volume can be useful markers for monitoring treatment response, while the neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio can also assist in detecting early relapse.

Detection of circulating anti-keratinocyte autoantibodies in feline pemphigus foliaceus

BACKGROUND

Circulating anti-keratinocyte immunoglobulin (Ig)G targeting desmosomal proteins have been identified in people and dogs with pemphigus foliaceus (PF). By contrast, detection attempts in PF-affected cats have been largely unsuccessful.

HYPOTHESIS/OBJECTIVES

To detect circulating anti-keratinocyte autoantibodies in PF-affected cats and determine their titres and tissue-staining patterns.

ANIMALS

Thirty PF-affected cats were compared to 11 specific-pathogen free, 15 healthy and 31 allergic cats.

METHODS AND MATERIALS

Sera were tested by indirect immunofluorescence on canine footpad and buccal mucosal substrates.

RESULTS

Circulating, anti-keratinocyte IgG with a suprabasilar, web-like (intercellular) pattern were detected in the majority of PF-affected cats (23 of 30, 77%), some allergic cats (six of 31, 19%) and one healthy cat (7%). Both footpad epidermis and buccal mucosa were positive in the majority of seropositive PF-affected cats (21 of 23, 91%), and in only one of six (17%) seropositive allergic cats. Staining was limited to the footpad in the remaining seropositive PF-affected and allergic cats and one seropositive healthy cat. Reciprocal IgG titres were significantly higher in PF-affected cats compared to controls (Dunn's post-test, P < 0.0001). Anti-keratinocyte IgM, IgA or IgE were not detected in any sera.

CONCLUSIONS AND CLINICAL IMPORTANCE

These results confirm the presence of circulating anti-keratinocyte IgG in a majority of PF-affected cats and in a small percentage of healthy and allergic cats. Although the molecular target and pathogenic nature of the antibodies remains unknown, the detection of positive immunostaining on buccal mucosal tissue, in addition to the footpad, suggests that the major target antigen of feline PF differs from that reported in dogs.

Successful treatment with thalidomide for pemphigus vulgaris

Background:

Pemphigus vulgaris (PV) is a potentially life-threatening mucocutaneous autoimmune blistering disease characterized by suprabasal acantholysis, causing painful mucocutaneous blisters and erosions. Current mainstay therapy for pemphigus is systemic corticosteroids in combination with or without immunosuppressive adjuvants, which may cause severe adverse effects and seriously impact on the quality of life in pemphigus patients. The objective of this study was to evaluate the efficacy and safety of thalidomide therapy in patients with PV.

Methods:

This study examined six PV patients from June 5, 2017, to November 11, 2018, in the dermatology department of Peking Union Medical College Hospital. Treatment with thalidomide was applied at a dose of 50–100 mg/day for disease control.

Results:

The mean age of the six patients (two male and four female patients) at the time of thalidomide therapy initiation was 50.2 years (range: 38–67 years), and the total duration of follow-up after thalidomide therapy was 13.2 months (range: 5–25 months). All patients responded favorably to thalidomide treatment, and three patients showed a dramatic reduction in anti-Dsg3 autoantibodies in the serologic examinations within 1 year. Five patients were found to have mucosal involvement. Mild adverse effects were noted in three patients, which could be managed after the application of symptomatic treatment and did not interfere with the pemphigus therapy.

Conclusion:

These results demonstrate that thalidomide could be an effective and safe option for PV patients, especially those who are concerned about steroid-induced severe complications, and have mucosal diseases.

Nineteen-year retrospective evaluation of pemphigus in a single dermatology centre in Istanbul, Turkey

Introduction

Pemphigus is an autoimmune intra-epidermal bullous disease of the skin and mucosae.

Aim

To retrospectively evaluate the course, prognosis and clinical features of pemphigus.

Material and methods

The files of 196 pemphigus patients admitted to our clinic between December 1995 and December 2014 were collected and analysed.

Results

The male to female ratio among patients was 1 : 1.88. Pemphigus vulgaris (PV) was the most common clinical variant observed in 175 (89.3%) of the patients, followed by pemphigus foliaceus (PF) in 14 (7.1%) of the patients. The mean patient age at disease onset was 50 years. PV presented itself as skin lesions in 55 (31.4%) of the patients and as oral mucosa lesions in 120 (68.6%) of the patients. Complete remission and treatment withdrawal were obtained in 112 (57.1%) of the patients, for a mean period of 2.91 ±2.66 years (range: 4 months to 13 years). The mortality rate was 6%, and relapse occurred in 16 (14.3%) of the patients for a mean relapse period of 2.15 ±1.88 years (range: 6 months to 7 years). Mucocutaneous pemphigus (MCP) was the major clinical pattern observed in 96 (49%) of the patients.

Conclusions

Within our study population, pemphigus predominately affected females, and the most common clinical variant was PV, a subtype that frequently occurs in middle-aged individuals. MCP was the most common clinical pattern. Although MCP and higher doses of corticosteroids were needed to control pemphigus, they did not seem to influence the prognosis.

Mucocutaneous Diseases

Mucocutaneous diseases affecting the oral cavity are predominantly immune mediated or inflammatory. Three of the most common and clinically significant conditions are reviewed in this article: lichen planus, pemphigus vulgaris, and mucous membrane pemphigoid. Because oral manifestations may be the first or only manifestation of mucocutaneous diseases, oral health professionals play a critical role in the early diagnosis and multidisciplinary management of these conditions.

Evaluation of the pathogenicity of anti-desmoglein antibodies of pemphigus vulgaris patients using human organ culture assay

Anti-desmoglein (anti-Dsg) antibodies are key players in the pathogenesis of pemphigus vulgaris (PV) disease. We aimed to evaluate the pathogenicity of anti-Dsg antibodies of PV patients using human organ culture assay and to assess the correlation between the pathogenicity and the disease score. In this cross-sectional study, sera from 37 PV patients were included. The organ culture acantholysis index (OCAI) was calculated as (width of blister/total width of the specimen) × 100. The sera were analyzed using Dsg ELISAs and ethylenediaminetetraacetic acid (EDTA) treated ELISAs. OCAI ranged from 0 to 100%, median = 50%. There was a moderate significant correlation between OCAI and the disease severity, r = 0.503, p = 0.002. There was a moderate significant correlation between OCAI and non-Ca²⁺-dependent anti-Dsg3 and anti-Dsg1 antibodies, p values were 0.01 and 0.021, respectively. The OCAI was assessed along the disease time course of four patients. The OCAI fluctuated parallel to the disease severity along the time course of the four patients. Human organ culture assay is an objective tool that detects the pathogenicity of anti-desmoglein antibodies. It can be used before stopping systemic steroids especially in patients in remission with high titer or if the Dsg ELISA is not available.

Immunohistochemistry for Immunoglobulin G4 in the Diagnosis of Pemphigus

Introduction

Pemphigus comprises of a group of autoimmune bullous disorders with intraepithelial lesions involving the skin and mucous membranes. Pemphigus is characterized histologically by an intraepidermal blister and immunopathologically by the finding of in vivo bound immunoglobulin G (IgG) antibodies against desmosomal adhesion proteins on the surface of keratinocytes. Indirect immunofluorescence for IgG is considered as a gold standard method for diagnosis of this group of bullous disorders on the condition that fresh frozen tissue is accessible.

Aim

We designed a new diagnostic method by immunohistochemistry (IHC) for IgG4 on paraffin sections instead of fresh frozen tissue and evaluated sensitivity, specificity, and positive and negative predictive values of this method.

Materials and Methods

We searched our pathologic archive of pemphigus of 35 patients, including 29 cases of pemphigus vulgaris (PV) and 6 patients with pemphigus foliaceus (PF). In all cases, the diagnosis was confirmed by indirect immunofluorescence studies. Thirty-five specimens served as controls, including 31 specimens of safe margins of basal cell carcinoma and 4 specimens of normal skin. Sections with condensed and continuous immunoreactivity localized to the intercellular junctions of keratinocytes were considered as positive.

Results

Sensitivity of IgG4 was estimated to be 72.4% in PV group and 83.3% in PF group. The overall sensitivity and specificity of IgG4 IHC for diagnosis of pemphigus were 74.2% and 82.8%, respectively, in PV and PF groups. Furthermore, positive predictive value and negative predictive value were 81.2% and 76.3%, respectively.

Conclusion

Immunohistochemical labeling for IgG4 on paraffin-embedded tissue provides a sensitive and specific test for diagnosing pemphigus in a situation when fresh frozen tissue is unavailable.

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.

Sparking Fire Under the Skin? Answers From the Association of Complement Genes With Pemphigus Foliaceus

Skin blisters of pemphigus foliaceus (PF) present concomitant deposition of autoantibodies and components of the complement system (CS), whose gene polymorphisms are associated with susceptibility to different autoimmune diseases. To investigate these in PF, we evaluated 992 single-nucleotide polymorphisms (SNPs) of 44 CS genes, genotyped through microarray hybridization in 229 PF patients and 194 controls. After excluding SNPs with minor allele frequency <1%, out of Hardy-Weinberg equilibrium in controls or in strong linkage disequilibrium (r2 ≥ 0.8), 201 SNPs remained for logistic regression. Polymorphisms of 11 genes were associated with PF. MASP1 encodes a crucial serine protease of the lectin pathway (rs13094773: OR = 0.5, p = 0.0316; rs850309: OR = 0.23, p = 0.03; rs3864098: OR = 1.53, p = 0.0383; rs698104: OR = 1.52, p = 0.0424; rs72549154: OR = 0.55, p = 0.0453). C9 (rs187875: OR = 1.46, p = 0.0189; rs700218: OR = 0.12, p = 0.0471) and C8A (rs11206934: OR = 4.02, p = 0.0323) encode proteins of the membrane attack complex (MAC) and C5AR1 (rs10404456: OR = 1.43, p = 0.0155), a potent anaphylatoxin-receptor. Two encode complement regulators: MAC-blocking CD59 (rs1047581: OR = 0.62, p = 0.0152) and alternative pathway-blocking CFH (rs34388368: OR = 2.57, p = 0.0195). One encodes opsonin: C3 (rs4807895: OR = 2.52, p = 0.0239), whereas four encode receptors for C3 fragments: CR1 (haplotype with rs6656401: OR = 1.37, p = 0.0382), CR2 (rs2182911: OR = 0.23, p = 0.0263), ITGAM (CR3, rs12928810: OR = 0.66, p = 0.0435), and ITGAX (CR4, rs11574637: OR = 0.63, p = 0.0056). Associations reinforced former findings, regarding differential gene expression, serum levels, C3, and MAC deposition on lesions. Deregulation of previously barely noticed processes, e.g., the lectin and alternative pathways and opsonization-mediated phagocytosis, also modulate PF susceptibility. The results open new crucial avenues for understanding disease etiology and may improve PF treatment through additional therapeutic targets.

Monopathogenic vs multipathogenic explanations of pemphigus pathophysiology

This viewpoint highlights major, partly controversial concepts about the pathogenesis of pemphigus. The monopathogenic theory explains intra-epidermal blistering through the "desmoglein (Dsg) compensation" hypothesis, according to which an antibody-dependent disabling of Dsg 1- and/or Dsg 3-mediated cell-cell attachments of keratinocytes (KCs) is sufficient to disrupt epidermal integrity and cause blistering. The multipathogenic theory explains intra-epidermal blistering through the "multiple hit" hypothesis stating that a simultaneous and synchronized inactivation of the physiological mechanisms regulating and/or mediating intercellular adhesion of KCs is necessary to disrupt epidermal integrity. The major premise for a multipathogenic theory is that a single type of autoantibody induces only reversible changes, so that affected KCs can recover due to a self-repair. The damage, however, becomes irreversible when the salvage pathway and/or other cell functions are altered by a partnering autoantibody and/or other pathogenic factors. Future studies are needed to (i) corroborate these findings, (ii) characterize in detail patient populations with non-Dsg-specific autoantibodies, and (iii) determine the extent of the contribution of non-Dsg antibodies in disease pathophysiology.

Proteomic Analysis of Pemphigus Autoantibodies Indicates a Larger, More Diverse, and More Dynamic Repertoire than Determined by B Cell Genetics

In autoantibody-mediated diseases such as pemphigus, serum antibodies lead to disease. Genetic analysis of B cells has allowed characterization of antibody repertoires in such diseases but would be complemented by proteomic analysis of serum autoantibodies. Here, we show using proteomic analysis that the serum autoantibody repertoire in pemphigus is much more polyclonal than that found by genetic studies of B cells. In addition, many B cells encode pemphigus autoantibodies that are not secreted into the serum. Heavy chain variable gene usage of serum autoantibodies is not shared among patients, implying targeting of the coded proteins will not be a useful therapeutic strategy. Analysis of autoantibodies in individual patients over several years indicates that many antibody clones persist but the proportion of each changes. These studies indicate a dynamic and diverse autoantibody response not revealed by genetic studies and explain why similar overall autoantibody titers may give variable disease activity.

Evaluation of anti-desmoglein-1 and anti-desmoglein-3 autoantibody titers in pemphigus patients at the time of the initial diagnosis and after clinical remission

It has been suggested that anti-desmoglein autoantibody titers could be helpful in follow-up and therapeutic management of pemphigus patients. However, there is no consensus regarding the relationship between anti-desmoglein autoantibody titers and clinical activity of pemphigus.The aim of our study was to evaluate if clinical remission of pemphigus relates to the presence of anti-desmoglein autoantibodies.Thirty patients with pemphigus vulgaris and 7 patients with pemphigus foliaceous were included in the study. Assessment of autoantibody titers was carried out at the time of the initial diagnosis and after the clinical remission using an enzyme-linked immunosorbent assay-based assay.Our results indicate that pemphigus clinical remission did not necessarily imply a serological remission, and consequently it is necessary to establish if withdrawal of the immunosuppressive regimen in pemphigus should be based exclusively on the achievement of clinical remission or also on the serological findings.

Rituximab in pemphigus

Pemphigus is a severe autoimmune blistering disease mediated by pathogenic anti-desmoglein antibodies leading to an inter keratinocyte disjunction. Rituximab is a monoclonal antibody that binds to the CD-20 antigen of B lymphocytes, which causes B-cell depletion and a subsequent reduction in pathogenic autoantibodies. Its therapeutic role in pemphigus has been progressively growing with increasing evidence of successful outcomes. Rituximab was initially off-labeled used as an alternative in patients with recalcitrant or relapsing pemphigus and in patients with contraindications to systemic corticosteroids. Recently, a large randomized clinical trial has shown that first-line use of rituximab combined with short-term prednisone regimen was both more effective and potentially safer than a standard regimen of high doses of corticosteroids in patients with moderate to severe pemphigus.

Pemphigus

Pemphigus is a group of IgG-mediated autoimmune diseases of stratified squamous epithelia, such as the skin and oral mucosa, in which acantholysis (the loss of cell adhesion) causes blisters and erosions. Pemphigus has three major subtypes: pemphigus vulgaris, pemphigus foliaceus and paraneoplastic pemphigus. IgG autoantibodies are characteristically raised against desmoglein 1 and desmoglein 3, which are cell-cell adhesion molecules found in desmosomes. The sites of blister formation can be physiologically explained by the anti-desmoglein autoantibody profile and tissue-specific expression pattern of desmoglein isoforms. The pathophysiological roles of T cells and B cells have been characterized in mouse models of pemphigus and patients, revealing insights into the mechanisms of autoimmunity. Diagnosis is based on clinical manifestations and confirmed with histological and immunochemical testing. The current first-line treatment is systemic corticosteroids and adjuvant therapies, including immunosuppressive agents, intravenous immunoglobulin and plasmapheresis. Rituximab, a monoclonal antibody against CD20⁺ B cells, is a promising therapeutic option that may soon become first-line therapy. Pemphigus is one of the best-characterized human autoimmune diseases and provides an ideal paradigm for both basic and clinical research, especially towards the development of antigen-specific immune suppression treatments for autoimmune diseases.

Validation of chemiluminescent enzyme immunoassay in detection of autoantibodies in pemphigus and pemphigoid

BACKGROUND

A novel chemiluminescent enzyme immunoassay (CLEIA) was recently developed to quantify autoantibodies specific for desmogleins (Dsgs) and BP180, the target antigens of pemphigus and pemphigoid. This assay is automated and highly accurate and efficient.

OBJECTIVE

To validate the use of the CLEIA for detection of autoantibodies during the clinical courses of patients with pemphigus and pemphigoid.

METHODS

To define cut-off values for Dsg1, Dsg3, and BP180, we evaluated 47 serum samples from patients with pemphigus foliaceus (PF), 59 from those with pemphigus vulgaris (PV), 52 from those with bullous pemphigoid (BP), and 995 from healthy individuals. We also evaluated any fluctuations in CLEIA titers according to disease activity during the clinical course of 10 cases each of PF, PV, and BP. We used clinical symptom scores, the pemphigus disease area index (PDAI) and the bullous pemphigoid disease area index (BPDAI), to evaluate disease activity.

RESULTS

The cut-off values for the CLEIA titers determined by the Youden index were 15.4U/mL for Dsg1, 14.9U/mL for Dsg3, and 16.8U/mL for BP180. CLEIA titers fluctuated in parallel with the PDAI/BPDAI scores in 28 of the 30 cases with PF, PV, or BP. Although the CLEIA and enzyme-linked immunosorbent assay (ELISA) values in the same samples differed substantially in some cases, the concordance rates of positive/negative results between the CLEIA and ELISA were 96% for Dsg1, 97% for Dsg3, and 96% for BP180.

CONCLUSION

The CLEIA, a newly developed, highly effective autoantibody detection system, is as reliable as ELISA for evaluation of the clinical courses of pemphigus and pemphigoid.

A reciprocal HLA-Disease Association in Rheumatoid Arthritis and Pemphigus Vulgaris

Human leukocyte antigens (HLA) have been extensively studied as being antigen presenting receptors, but many aspects of their function remain elusive, especially their association with various autoimmune diseases. Here we discuss an illustrative case of the reciprocal relationship between certain HLA-DRB1 alleles and two diseases, rheumatoid arthritis (RA) and pemphigus vulgaris (PV). RA is strongly associated with HLA-DRB1 alleles that encode a five amino acid sequence motif in the 70-74 region of the DR beta chain, called the shared epitope (SE), while PV is associated with the HLA-DRB1*04:02 allele that encodes a different sequence motif in the same region. Interestingly, while HLA-DRB1*04:02 confers susceptibility to PV, this and other alleles that encode the same sequence motif in the 70-74 region of the DR beta chain are protective against RA. Currently, no convincing explanation for this antagonistic effect is present. Here we briefly review the immunology and immunogenetics of both diseases, identify remaining gaps in our understanding of their association with HLA, and propose the possibility that the 70-74 DR beta epitope may contribute to disease risk by mechanisms other than antigen presentation.

[Pemphigus. Model disease for targeted therapy]

BACKGROUND

Pemphigus is a severe bullous autoimmune dermatosis that represents a clinical challenge despite high-dose immunosuppressive therapy due to the therapy-related comorbidities and the lack of long-term control of disease activity.

OBJECTIVES

Which targeted therapies are currently used in pemphigus and which innovative therapeutic strategies are in clinical development?

MATERIALS AND METHODS

A review of the literature in PubMed was performed under consideration of the current guideline for the treatment of pemphigus as well as of our own results. Discussion of basic findings and results of targeted therapies in autoantibody-mediated autoimmune disorders were taken into account.

RESULTS

Immunapheresis and high-dose intravenous immunoglobulins with the aim of reducing circulating autoantibodies have been successfully used in the treatment of pemphigus. Depletion of autoreactive B-lymphocytes provides the rationale for the use of the monoclonal anti-CD20 antibody rituximab which demonstrated long-term clinical remission of pemphigus in clinical trials. Current developments include the investigation of humanised B-cell depleting antibodies in other B-cell driven autoimmune disorders as well as the identification of new cellular and molecular target structures that are essential in the humoral autoimmune cascade and exert important immune regulatory functions, respectively.

CONCLUSIONS

The well-characterised basic pathogenesis of pemphigus results in targeted therapies. Currently, therapies aiming at rapid reduction of circulating autoantibodies and the depletion of autoreactive B-cells are in clinical use. More cellular and molecular target structures are being investigated in other autoantibody-driven autoimmune disorders and they provide promising candidates for innovative pathogenesis-related therapeutic strategies in pemphigus in the future.

Increased oxidative stress in pemphigus vulgaris is related to disease activity and HLA-association

Pemphigus vulgaris (PV) is a rare blistering skin disorder characterized by the disadhesion of keratinocytes due to autoantibody attack against epidermal targets including desmoglein (Dsg) 3, Dsg 1 and possibly other adhesion and non-adhesion molecules. The mechanisms leading to immune-mediated pathology in PV are multifactorial and not fully understood. Recently, oxidative stress (antioxidant/oxidant disequilibrium) has been proposed as a contributory mechanism of autoimmune skin diseases, including PV. In this study, we directly assessed oxidative stress via measurement of total antioxidant capacity (TAC) using ELISA in 47 PV patients, 25 healthy controls and 18 bullous pemphigoid (BP) patients. We also performed microarray gene expression analysis on a separate set of 21 PV patients and 10 healthy controls to evaluate transcriptional dysregulation in oxidative stress-related pathways. Our data indicate that there is a significant reduction in TAC levels in PV patients compared with healthy controls, as well as BP patients. Furthermore, PV patients with active disease have significantly lower TAC levels than PV patients in remission. We also find that HLA allele status has a significant influence on oxidative stress. These findings are corroborated by microarray analysis showing differentially expressed genes involved in oxidative stress between the aforementioned groups. Collectively, our findings provide support for a role of oxidative stress in PV. Whether increased oxidative stress leads to disease manifestation and/or activity, or if disease activity leads to increased oxidative stress remains unknown. Future longitudinal studies may help to further elucidate the relationship between PV and oxidative stress.

Grading criteria for disease severity by pemphigus disease area index

Pemphigus is a group of autoimmune blistering diseases that affect the skin and mucous membranes. A reliable and accurate disease severity tool to assess pemphigus severity is crucial for managing pemphigus and for clinical trials. The purpose of this study was to compare the pemphigus disease area index activity score (PDAI), the Japanese pemphigus disease severity score (JPDSS) and the physician's subjective impression, and also to find appropriate severity grading cut-offs for the PDAI. We also evaluated the correlation between PDAI activity score and the JPDSS. Thirty-seven pemphigus patients and 110 assessments were analyzed in this study. The optimal points of pemphigus disease severity score in PDAI were: mild (0-8), moderate (9-24) and severe (≥25). In mild or moderate cases, the JPDSS was well correlated with the PDAI, but in severe cases the JPDSS reached a plateau at a PDAI score of approximately 30. The PDAI evaluates disease severity more accurately than the JPDSS, particularly in severe cases. The PDAI is not only a useful tool to measure the extent of cutaneous lesions, but also an excellent scoring system for evaluating pemphigus disease severity.

Multiplexed autoantigen microarrays identify HLA as a key driver of anti-desmoglein and -non-desmoglein reactivities in pemphigus

Patients with pemphigus vulgaris (PV) harbor antibodies reactive against self-antigens expressed at the surface of keratinocytes, primarily desmoglein (Dsg) 3 and, to a lesser extent, Dsg1. Conventionally, only antibodies targeting these molecules have been thought to contribute to disease pathogenesis. This notion has been challenged by a growing pool of evidence that suggests that antibodies toward additional targets may play a role in disease. The aims of this study were to (i) establish high-throughput protein microarray technology as a method to investigate traditional and putative autoantibodies (autoAbs) in PV and (ii) use multiplexed protein array technology to define the scope and specificity of the autoAb response in PV. Our analysis demonstrated significant IgG reactivity in patients with PV toward the muscarinic acetylcholine receptor subtypes 3, 4, and 5 as well as thyroid peroxidase. Furthermore, we found that healthy first- and second-degree relatives of patients with PV express autoAbs toward desmoglein and non-Dsg targets. Our analysis also identified genetic elements, particularly HLA, as key drivers of autoAb expression. Finally, we show that patients with PV exhibit significantly reduced IgM reactivity toward disease-associated antigens relative to controls. The use of protein microarrays to profile the autoAb response in PV advanced the current understanding of disease and provided insight into the complex relationship between genetics and disease development.

Salivary desmoglein enzyme-linked immunosorbent assay for diagnosis of pemphigus vulgaris: a noninvasive alternative test to serum assessment

Background. Serum desmoglein enzyme-linked immunosorbent assay (ELISA) is used for the diagnosis and monitoring of pemphigus diseases. Objectives. To compare the diagnostic accuracy of salivary antidesmoglein (Dsg) 1 and 3 ELISA in the diagnosis of pemphigus vulgaris (PV) patients with that of serum desmogleins ELISA. Methods. Eighty-six untreated PV patients and 180 age- and sex-matched PV-free controls were recruited in this case-control study. PV was diagnosed based on clinical, histopathological, and direct immunofluorescence findings. After processing, serum and salivary anti-Dsg 1 and 3 were measured by the ELISA method using Euroimmun kit (Lübeck, Germany). Results. Using the cut-off point of 20 relative units (RU)/mL, the serum anti-Dsg 1 and 3 ELISA were positive in 62 (72.1%) and 83 (96.5%) patients, respectively, and the salivary anti-Dsg 1 and 3 ELISA were positive in 31 (36.1%) and 63 (73.3%) patients, respectively. The specificity of salivary anti-Dsg 1 and anti-Dsg 3 were both 98.9%. Optimal cut-off values of 7.7 and 13.4 RU/mL were determined for the salivary anti-Dsg 1 and anti-Dsg 3 ELISA, respectively. Conclusion. Salivary anti-Dsg 1 and 3 ELISA with high specificities (98.9%) could be suggested as safe and noninvasive methods for the diagnosis of PV when obtaining a blood sample is difficult.

Pemphigus vulgaris localized to the tongue

BACKGROUND

Pemphigus vulgaris is an autoimmune blistering disease that may initially present as localized lesions. It rarely remains localized throughout its clinical course.

OBSERVATIONS

A 53-year-old woman with non-progressive pemphigus vulgaris localized to the tongue for 18 years is presented. Clinical examination showed erosions and ulcerations limited to the lateral margins of the tongue. Patient was treated with sublesional triamcinolone-acetonide injections as lesions recurred. Finally, triamcinolone- acetonide injections at three weeks intervals for three months induced a longterm sustained clinical remission for 18 months. The indirect immunofluorescence did not correlate with disease activity. Anti-desmoglein 3 antibodies (ELISA) remained elevated throughout the clinical course and during remission.

CONCLUSIONS

This case highlights the recognition of localized pemphigus vulgaris and demonstrates the importance of local therapy and its potential to induce longterm remission. Similar report of additional cases may create a standard of care for non-progressive, localized pemphigus.

[Transition from pemphigus vulgaris to pemphigus foliaceus: a case report]

BACKGROUND

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are the two main subtypes of auto-immune pemphigus, each having different clinical, histological and immunopathological features. We report the case of a patient initially with typical PV who relapsed within 2years, presenting clinically, histologically and immunologically typical PF.

PATIENTS AND METHODS

A 47-year old man presented in March 2008 with clinically, histologically and serologically typical PV and treated with systemic corticosteroids alone (prednisone: 1mg/kg per day) then combined with a cycle of rituximab, which resulted in complete remission. After discontinuation of therapy (duration: 26months), he relapsed 6 months later with PF presenting clinical, histological and serological characteristics typical of this condition.

DISCUSSION

This is a rare case of complete transition from PV to PF in clinical, histological and serological terms, and the first case occurring after initial treatment with rituximab.

Pemphigus

Pemphigus vulgaris and paraneoplastic pemphigus are 2 subtypes of pemphigus that involve the oral mucosa. These autoimmune blistering disorders have antibodies targeted against proteins of keratinocyte adhesion, thereby causing acantholysis. Clinical findings include oral erosions and flaccid cutaneous bullae and erosions. Further malignancy workup in patients with suspected paraneoplastic pemphigus is warranted. Retrospective uncontrolled studies suggest that immunosuppressive agents reduce mortality in pemphigus vulgaris and cohort uncontrolled studies of rituximab, a monoclonal antibody against CD20, suggest it is an effective treatment for refractory patients. Ongoing studies will define its role in early disease.

A higher correlation of the antibody activities against the calcium-dependent epitopes of desmoglein 3 quantified by ethylenediaminetetraacetic acid-treated enzyme-linked immunosorbent assay with clinical disease activities of pemphigus vulgaris

BACKGROUND

Nonpathogenic anti-desmoglein (Dsg) 3 antibodies can be found in pemphigus vulgaris (PV) patients' sera. Previously, ethylenediaminetetraacetic acid (EDTA)-treated enzyme-linked immunosorbent assay (ELISA) was found to detect only nonpathogenic anti-Dsg3 antibodies against the non-calcium (Ca(2+))-dependent epitopes.

OBJECTIVE

We examined whether the calculated anti-Dsg3 antibody titer for Ca(2+)-dependent epitopes, using the conventional and EDTA-treated ELISAs, correlated better with the disease activity of PV.

METHODS

We analyzed 123 serum samples from 19 PV patients. Of these samples, there were 52 samples from 15 PV patients obtained in asymptomatic phases. The difference between conventional Dsg3 ELISA index and EDTA-treated Dsg3 ELISA index was calculated as the anti-Dsg3 antibody activity for Ca(2+)-dependent conformational epitopes (conformational Dsg3 ELISA index). We analyzed the correlation between Dsg3 ELISA index values and the pemphigus disease area index (PDAI). Moreover, we examined whether the conformational Dsg3 ELISA index fluctuated in parallel with the disease activity during clinical courses of 6 PV patients. We evaluated the pathogenicity of anti-Dsg3 antibodies detected in remission phases using a dissociation assay.

RESULTS

The conventional Dsg3 ELISA index showed a high positive rate in the asymptomatic phase of PV. By contrast, the conformational Dsg3 ELISA index showed a much closer correlation to the disease activity when monitored in individual cases. Nonpathogenic anti-Dsg3 antibodies were detected in these cases.

CONCLUSION

The conformational Dsg3 ELISA index reflected the pathogenicity of anti-Dsg3 antibodies more accurately than the conventional Dsg3 ELISA index. Using both conventional and EDTA-treated ELISAs would be useful in monitoring the disease activity of PV.

Pemphigus vulgaris autoantibody profiling by proteomic technique

Pemphigus vulgaris (PV) is a mucocutaneous blistering disease characterized by IgG autoantibodies against the stratified squamous epithelium. Current understanding of PV pathophysiology does not explain the mechanism of acantholysis in patients lacking desmoglein antibodies, which justifies a search for novel targets of pemphigus autoimmunity. We tested 264 pemphigus and 138 normal control sera on the multiplexed protein array platform containing 701 human genes encompassing many known keratinocyte cell-surface molecules and members of protein families targeted by organ-non-specific PV antibodies. The top 10 antigens recognized by the majority of test patients’ sera were proteins encoded by the DSC1, DSC3, ATP2C1, PKP3, CHRM3, COL21A1, ANXA8L1, CD88 and CHRNE genes. The most common combinations of target antigens included at least one of the adhesion molecules DSC1, DSC3 or PKP3 and/or the acetylcholine receptor CHRM3 or CHRNE with or without the MHC class II antigen DRA. To identify the PV antibodies most specific to the disease process, we sorted the data based on the ratio of patient to control frequencies of antigen recognition. The frequency of antigen recognition by patients that exceeded that of control by 10 and more times were the molecules encoded by the CD33, GP1BA, CHRND, SLC36A4, CD1B, CD32, CDH8, CDH9, PMP22 and HLA-E genes as well as mitochondrial proteins encoded by the NDUFS1, CYB5B, SOD2, PDHA1 and FH genes. The highest specificity to PV showed combinations of autoantibodies to the calcium pump encoded by ATP2C1 with C5a receptor plus DSC1 or DSC3 or HLA-DRA. The results identified new targets of pemphigus autoimmunity. Novel autoantibody signatures may help explain individual variations in disease severity and treatment response, and serve as sensitive and specific biomarkers for new diagnostic assays in PV patients.

Autoimmune reactivity against precursor form of desmoglein 1 in healthy Tunisians in the area of endemic pemphigus foliaceus

BACKGROUND

Desmoglein 1 (Dsg1), the pemphigus foliaceus (PF) antigen, is produced as a precursor (preDsg1) and is transported to the cell surface as the mature form (matDsg1). Recent studies show that B cells from North American individuals without pemphigus can potentially produce anti-preDsg1 IgG antibodies, but ELISA screening of large numbers of normal people in North America and Japan hardly ever shows circulating antibodies against preDsg1 or matDsg1. In contrast, in Tunisia, where PF is endemic, anti-Dsg1 IgGs are frequently detected in healthy individuals.

OBJECTIVE

To characterize these anti-Dsg1 antibodies from normal individuals in Tunisia.

METHODS

Sera from 16 healthy individuals and 9 PF patients in the endemic PF area in Tunisia, and sera from Japanese non-endemic PF patients were analyzed by immunoprecipitation-immunoblotting using recombinant proteins of preDsg1, matDsg1, and domain-swapped Dsg1/Dsg2 molecules.

RESULTS

Sera from normal Tunisian individuals reacted to preDsg1 alone (8/16) or more strongly to preDsg1 than to matDsg1 (7/16), while those from all Tunisian PF patients and Japanese non-endemic PF patients reacted similarly to preDsg1 and matDsg1, or preferentially to matDsg1. The epitopes recognized by anti-Dsg1 IgGs from normal Tunisian individuals were more frequently found in the C-terminal extracellular domains (EC3 to EC5), while those in Tunisian endemic PF patients were more widely distributed throughout the extracellular domains, suggesting IgGs against EC1 and EC2 developed during disease progression.

CONCLUSIONS

These findings indicate that IgG autoantibodies against Dsg1 are mostly raised against preDsg1 and/or C-terminal domains of Dsg1 in healthy Tunisians in the endemic area of PF.

Anti-skin specific autoantibodies detected by a new immunofluorescence multiplex biochip method in patients with autoimmune bullous diseases

BACKGROUND

Autoimmune blistering skin diseases are a heterogeneous group of diseases characterized by autoantibodies against structural components of the skin. In pemphigus vulgaris (PV) autoantibodies react mainly with desmoglein 3 (Dsg3) alone and/or in combination with desmoglein 1 (Dsg1). In bullous pemphigoid (BP) autoantibodies target two hemidesmosomal proteins, BP180 and BP230.

OBJECTIVE

To evaluate the diagnostic accuracy of a new indirect immunofluorescence (IIF) multiplex biochip method for the detection of anti-skin specific autoantibodies.

METHODS

Sera from 36 patients with PV and from 40 patients with BP were collected. The control group included 54 patients with other skin diseases and 40 healthy subjects. The detection of circulating autoantibodies to Dsg1, Dsg3, BP230 and BP180 was performed with a new IIF multiplex biochip method and with two currently commercially available ELISA methods.

RESULTS

The multiplex IIF method showed a high diagnostic sensitivity (100%) for PV on cells transfected with Dsg3. In patients with BP, the positivity to the BP180 antigen was higher (90%) than that on monkey esophagus (50%) and on cells transfected with BP230 (40%). A good rate of agreement was observed among methods (IIF vs. ELISA) and among ELISA systems.

CONCLUSIONS

The new multiplex biochip IIF method has a high diagnostic accuracy for the diagnosis of PV and BP, comparable to ELISA methods, and is able to screen autoimmune bullous diseases.

Detection of antibodies against the non-calcium-dependent epitopes of desmoglein 3 in pemphigus vulgaris and their pathogenic significance

BACKGROUND

Antidesmoglein (anti-Dsg) 3 serum antibody titres are usually correlated with the disease activity of pemphigus vulgaris (PV), but some patients retain high titres even in remission.

OBJECTIVES

The aim of our study was to determine whether anti-Dsg3 antibodies in PV sera recognized calcium (Ca(2+) )-dependent or non-Ca(2+) -dependent epitopes, and to evaluate their pathogenicity.

METHODS

Dsg3 baculoprotein-coated enzyme-linked immunosorbent assay (ELISA) plates were treated with 0.5 mmol L(-1) ethylenediaminetetraacetic acid (EDTA). The binding ability of anti-Dsg3 monoclonal antibodies (mAbs) was analysed. Eight of the 83 patients with PV who were screened had elevated Dsg3 ELISA index values > 00 in remission. The binding ability of these PV sera was analysed. We evaluated the pathogenicity of anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes using a dissociation assay.

RESULTS

The reactivity of pathogenic anti-Dsg3 mAbs against the Ca(2+) -dependent epitopes diminished markedly in the EDTA-treated ELISA, whereas no such reduction was observed in mAbs against the non-Ca(2+) -dependent epitopes. The sera of all the patients contained antibodies against both Ca(2+) -dependent and non-Ca(2+) -dependent epitopes. In six out of the eight patients, the ratio of antibodies against Ca(2+) -dependent to non-Ca(2+) -dependent epitopes decreased in remission. EDTA-treated Dsg3 baculoproteins adsorbed anti-Dsg3 serum antibodies against the non-Ca(2+) -dependent epitopes, but the remnant PV antibodies retained the ability to induce acantholysis in the dissociation assay.

CONCLUSIONS

We have established an assay to measure indirectly the titres of anti-Dsg3 serum antibodies against the Ca(2+) -dependent epitopes, based on the differences between EDTA-untreated and EDTA-treated ELISA index values, as a routine laboratory test to reflect the pathogenic anti-Dsg3 serum antibody titres more accurately.

Urban legends: pemphigus vulgaris

Pemphigus vulgaris (PV) is the most common type of pemphigus. PV pathogenesis is still debated, and treatment remains challenging. We investigated five controversial topics: (1) What are the target antigens in PV? (2) Do desmogleins adequately address PV pathophysiology? (3) How does acantholysis occur in PV? (4) Is PV still a lethal disease? (5) What is the role of rituximab (RTX) in PV treatment? Results from extensive literature searches suggested the following: (1) Target antigens of PV include a variety of molecules and receptors that are not physically compartmentalized within the epidermis. (2) PV is caused by a variety of autoantibodies to keratinocyte self-antigens, which concur to cause blistering by acting synergistically. (3) The concept of apoptolysis distinguishes the unique mechanism of autoantibody-induced keratinocyte damage in PV from other known forms of cell death. (4) PV remains potentially life-threatening largely because of treatment side effects, but it is uncertain which therapies carry the highest likelihood of lethal risk. (5) RTX is a very promising treatment option in patients with widespread recalcitrant or life-threatening PV. RTX's cost is an issue, its long-term side effects are still unknown, and randomized controlled trials are needed to establish the optimal dosing regimen.