Pemphigus and Pemphigoid: From Disease Mechanisms to Druggable Pathways

Demographic characteristics and disease severity associated with IgA/IgG deposition patterns in autoimmune bullous diseases: a cohort study based on a registry database

Background

Direct immunofluorescence (DIF) microscopy is the gold standard for diagnosing autoimmune bullous diseases (AIBDs), but the clinical significance of IgA and IgG co-deposition was unclear.

Objective

Investigate the demographic differences and disease severity among different IgG/IgA deposition patterns in DIF.

Methods

We conducted a retrospective cohort study based on a registry database that analyzed demographic data, involvement sites, and immunofluorescence patterns of patients with DIF biopsy. Patients were categorized into intercellular (group A) and basement membrane zone (group B) deposition patterns. Logistic regression models assessed associations between deposition status and demographic characteristics. Disease severity and prognosis were analyzed retrospectively through subgroup analyses.

Results

In group A, female gender (OR = 1.665, P = 0.011) and stronger IgG deposition (OR = 3.881, P < 0.001) were associated with IgA and IgG co-deposition. In group B, female gender (OR = 1.382, P = 0.002), stronger IgG deposition (OR = 2.673, P < 0.001), and mucosa tissue (OR = 3.052, P < 0.001) were associated with IgA and IgG co-deposition. IgA and IgG co-deposition in group A was associated with higher Pemphigus Disease Area Index scores (P = 0.036), while in group B, it correlated with mucosal involvement (P = 0.007). No differences in the proportion of disease severity scores improvement after 6 months of standard treatment were found in both groups.

Conclusions

Female gender, stronger IgG deposition, and mucosa tissue are key factors affecting IgA and IgG co-deposition in AIBD patients. For clinical correlation, patients with IgA and IgG co-deposition in pemphigus exhibit more severe disease severity compared with those with IgG deposition only, while patients with co-deposition in pemphigoid are more prone to mucosal involvement.

Juvenile pemphigus vulgaris: A narrative review

Pemphigus vulgaris is a chronic autoimmune dermatosis that primarily affects the skin and mucous membranes. Juvenile pemphigus vulgaris (JPV), a pediatric variant of pemphigus vulgaris, displays unusual features that may mimic other mucosal lesions. This similarity leads to diagnostic and therapeutic difficulties, often causing delays in diagnosis. Primary treatment consists of systemic corticosteroids and immunosuppressive agents, with biological therapies, such as rituximab, emerging as potential alternatives. Timely diagnosis and treatment are essential to improve prognosis and reduce complications related to long-term immunosuppressive therapy. A comprehensive electronic and manual literature search was conducted using various databases to consolidate the existing literature on JPV, focusing on its epidemiology, pathogenesis, clinical presentation, diagnosis, treatment options, and long-term outcomes in pediatric patients. A detailed review focusing on JPV has been conducted over the last 10 years (2014-2024). A literature review identified 37 cases of JPV in 16 studies. Owing to the rarity of JPV, much of the available evidence relies on case reports and case series, resulting in poorly defined response rates to different treatment options. Additionally, long-term monitoring of patients with disease recurrence is lacking. By identifying gaps in the current knowledge and offering a comprehensive overview, this review seeks to enhance awareness and guide future research and management strategies for JPV.

Feline immune-mediated skin disorders: Part 1

PRACTICAL RELEVANCE

Cutaneous immune-mediated diseases in cats can present with clinical signs of erythema, hair loss, scaling/crusting and erosions with or without pruritis, mimicking many differential diagnoses such as hypersensitivity dermatitis and infections (eg, parasitic and fungal dermatitis). Veterinarians are encouraged to become familiar with the characteristic clinical features of various immune-driven skin disorders to permit early diagnosis and appropriate treatment.

CLINICAL CHALLENGES

Diagnosis and therapeutic management of feline immune-mediated skin diseases can be challenging. Although immune-mediated skin diseases in cats are rare, these can be associated with severe systemic clinical signs, which can lead to poor quality of life and owners electing euthanasia.

AIMS

In the first of a two-part article series, the clinical presentations of feline immune-mediated skin diseases related to the pemphigus complex, cutaneous lupus erythematosus, and thymoma- and non-thymoma-associated exfoliative dermatitis are reviewed and differential diagnoses, diagnosis and therapeutic approach are discussed. In Part 2, the equivalent is discussed for erythema multiforme, f Stevens-Johnson syndrome/toxic epidermal necrolysis spectrum, plasma cell pododermatitis, proliferative and necrotizing otitis externa, pseudopelade, alopecia areata and auricular chondritis.

EVIDENCE BASE

The information in this article is based on a review of the existing veterinary literature.

[CAR-T cells in Dermatology: Mechanisms of action and applications in autoimmune diseases]

Background

Chimeric Antigen Receptor T (CAR-T) cells have revolutionized the treatment of hematological malignancies and are expanding into autoimmune rheumatological diseases. In dermatology, they open a new therapeutic field for autoimmune disorders.

Objective

To evaluate the mechanisms of action and therapeutic applications of CAR-T cells in autoimmune dermatological diseases, exploring the challenges and future perspectives for their clinical application.

Material and methods

A thorough review was conducted in PubMed of preclinical and clinical studies on the application of CAR-T in dermatological diseases, selecting articles from the last 5 years with a focus on autoimmune diseases.

Results

The potential of CAR-T cells in autoimmune dermatological diseases is highlighted, such as in pemphigus vulgaris, where CAR-T cells targeting pathogenic anti-Dsg3 B cells have shown efficacy. In cutaneous lupus erythematosus, CAR-T cells directed at CD19 have achieved significant clinical remissions. Additionally, applications in psoriasis and melanoma are explored, although efficacy is limited by adverse factors.

Conclusions

CAR-T therapy represents a promising option for the management of refractory dermatological diseases, with favorable results in preclinical and clinical models. However, its clinical implementation faces challenges such as optimizing safety and reducing off-target effects. Future research should focus on next-generation CARs and clinical trials that validate their efficacy and safety profile in dermatology.

Canine and Feline Pemphigus Foliaceus-an Update on Pathogenesis and Treatment

Pemphigus foliaceus (PF) is one of the most common autoimmune skin diseases of dogs and cats and is characterized by the development of pustules, crusts, erosions, scales, and alopecia. Albeit poorly understood, the pathophysiology of canine and feline PF appears to involve immune dysregulation and immunoglobulin G autoantibodies that are directed against the keratinocyte cell surface. At present, the management of canine and feline PF relies on the long-term to lifelong prescription of immunosuppressive medications. Current knowledge on the pathogenesis of canine and feline PF, as well as traditional and emerging therapies used to treat both diseases, will be reviewed herein.

Pemphigus Vulgaris Autoantibodies Induce an Endoplasmic Reticulum Stress Response

Desmosomes are intercellular junctions that mediate cell-cell adhesion and are essential for maintaining tissue integrity. Pemphigus vulgaris (PV) is an autoimmune epidermal blistering disease caused by autoantibodies (IgG) targeting desmoglein 3, a desmosomal cadherin. PV autoantibodies cause desmosome disassembly and loss of cell-cell adhesion; however, the molecular signaling pathways that regulate these processes are not fully understood. Using high-resolution time-lapse imaging of live keratinocytes, we found that endoplasmic reticulum (ER) tubules make frequent and persistent contacts with internalizing desmoglein 3 puncta in keratinocytes treated with IgG of patients with PV. Biochemical experiments demonstrated that PV IgG activated ER stress signaling pathways, including both IRE1⍺ and PERK pathways, in cultured keratinocytes. Furthermore, ER stress transcripts were upregulated in the skin of patients with PV. Pharmacological inhibition of ER stress protects against PV IgG-induced desmosome disruption and loss of keratinocyte cell-cell adhesion, suggesting that ER stress may be an important pathomechanism and a therapeutically targetable pathway for PV treatment. These data support a model in which desmosome adhesion is integrated with ER function to serve as a cell adhesion stress sensor that is activated in blistering skin diseases.

Pemphigus relapse: Mechanisms, risk factors, and agents associated with disease recurrence

Pemphigus represents a spectrum of potentially life-threatening autoimmune-mediated skin blistering conditions caused by antibody production against desmoglein 1 and 3 (anti-DSG 1 and 3) in keratinocytes. Greater than 50% of pemphigus patients experience relapse, which complicates long-term medical management, including risks associated with re-treatment and complications such as infection and dehydration. This review aims to elucidate mechanisms, risk factors, and medications associated with pemphigus relapse. Mechanisms of relapse include the persistence of auto-reactive B-cell populations post-treatment and CD20- B-cell populations that reactivate after B-cell depletion therapy. Risk factors for relapse include high body surface area (BSA) of pemphigus involvement, high body mass index, high severity according to the Pemphigus Disease Area Index (PDAI) at onset, treatment delay, and high anti-DSG1 and DSG3 titers post-treatment. Targeted B-cell localization is associated with better clinical outcomes, including less frequent relapses. Rituximab is currently the gold standard of treatment for moderate-severe pemphigus and has relapse rates of 11%-44% in selected studies, with a mean time to relapse of 5.8 months to 36 months following treatment. Relapse rates across lymphoma dosing (375 mg/m2) versus rheumatoid arthritis dosing (1 g dosing weekly) was inconsistent; however, more frequent dosing, earlier treatment, and higher cumulative dosing were associated with lower relapse rates. Alternative agents that have clinical efficacy include corticosteroid monotherapy, mycophenolate mofetil, azathioprine, and intravenous immunoglobulin. Future studies should include head-to-head comparators over long follow-up periods to identify the best treatment agents associated with the least relapse risk.

IgG reactivity to different desmoglein-3 ectodomains in pemphigus vulgaris: novel panels for assessing disease severity

Introduction

Pemphigus vulgaris (PV) is an autoimmune disease characterized by IgG autoantibodies targeting desmoglein-3 (Dsg3), leading to blistering of mucous membranes and skin. Although commercial ELISA kits effectively diagnose PV, correlation with clinical phenotype remains unclear. This study assesses multiple panels for monitoring disease severity and activity by profiling IgG autoantibodies against Dsg3's various extracellular ectodomains.

Method

We designed and expressed different extracellular domains of Dsg3 in HEK293T cell line and developed 15 different ELISA panels, each using a single or multi ectodomains encompassing the entire extracellular region of Dsg3 to detect specific autoantibodies against the particular part of Dsg3.

Results

To validate our approach, we compared our ELISA panel for the full Dsg3 (EC1-5) against a commercial kit using 154 random serum samples from PV patients, demonstrating a strong correlation. For evaluation of IgG autoantibody profiles in our panels, 59 PV patients were included, along with 11 bullous pemphigoid patients, and 49 healthy controls. For all the included subjects, 15 predefined ELISA panels were tested. The IgG autoantibodies against EC1 were detected in 86% of patients with a positive full Dsg3 ectodomain (EC1-5) ELISA, with 26% against EC2, 14% for EC3, 29% for EC4, and 23% for EC5. Among the panels with multiple Dsg3 ectodomains, EC1-3 and EC1-4 were representative of the entire Dsg3 ectodomain in terms of ELISA positivity across all included patients. A significant correlation (P<0.05) was observed between ELISA optical density (OD) and Pemphigus Disease Area Index (PDAI) scores in five panels, EC1, EC2-3, EC2-5, and EC3-4 in addition to the full ectodomain. It suggests an association with disease severity. Interestingly, while the ELISA panel for the entire Dsg3 extracellular ectodomains did not differentiate disease phases, in three of our panels, including EC1, EC3-5, and EC2-5, ANOVA analysis showed a statistically significant difference between the groups of patients in remission, partial remission or persistent lesions, and those with active disease (new cases or relapse). Among these three panels, EC1 was the only one that showed a significant difference in the multiple comparisons analysis; patients in the active phase had higher levels of autoantibodies than those in 'partial remission or persistent lesions' and 'complete remission' groups.

Conclusion

The level of autoantibodies against EC1 was not only correlated with the full ectodomain but also associated with higher disease severity and active disease phase. This study indicates that a detailed autoantibody profile against Dsg3 ectodomains could serve as a marker for PV severity and activity which may potentially enhance early treatment initiation.

Targeted therapy for immune mediated skin diseases. What should a dermatologist know?

BACKGROUND

Molecularly targeted therapies, such as monoclonal antibodies (mAbs) and Janus Kinase inhibitors (JAKis), have emerged as essential tools in the treatment of dermatological diseases. These therapies modulate the immune system through specific signaling pathways, providing effective alternatives to traditional systemic immunosuppressive agents. This review aims to provide an updated summary of targeted immune therapies for inflammatory skin diseases, considering their pathophysiology, efficacy, dosage, and safety profiles.

METHODS

The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A systematic search was conducted on PubMed over the past 10 years, focusing on randomized clinical trials, case reports, and case series related to targeted immune therapies in dermatology. Eligibility criteria were applied, and data were extracted from each study, including citation data, study design, and results.

RESULTS

We identified 1360 non-duplicate articles with the initial search strategy. Title and abstract review excluded 1150, while a full-text review excluded an additional 50 articles. The review included 143 studies published between 2012 and 2022, highlighting 39 drugs currently under investigation or in use for managing inflammatory skin diseases.

STUDY LIMITATIONS

The heterogeneity of summarized information limits this review. Some recommendations originated from data from clinical trials, while others relied on retrospective analyses and small case series. Recommendations will likely be updated as new results emerge.

CONCLUSION

Targeted therapies have revolutionized the treatment of chronic skin diseases, offering new options for patients unresponsive to standard treatments. Paradoxical reactions are rarely observed. Further studies are needed to fully understand the mechanisms and nature of these therapies. Overall, targeted immune therapies in dermatology represent a promising development, significantly improving the quality of life for patients with chronic inflammatory skin diseases.

Dyspnea Due to Laryngeal Cicatricial Pemphigoid: A Case Report

Cicatricial pemphigoid (CP) is a rare, chronic, vesiculobullous disease characteristically affecting the mucous membranes and healing with cicatrization. Laryngeal involvement is rare and leads to airway stenosis. We present a 74-year-old Caucasian woman with CP, affecting the oral cavity, esophagus, lower eyelids, and larynx. Regardless of regular treatment with hydrocortisone and azathioprine, she developed bilateral cicatrization of the aryepiglottic folds and ovoid stenosis of the laryngeal introitus, leading to dyspnea. To avoid tracheostomy, we were able to utilize infraglottic high-frequency jet ventilation under total intravenous anesthesia to perform a CO2 laser supraglottoplasty with sectioning of the aryepiglottic folds. Post-operatively, her dyspnea at rest resolved; there was no progression at the six- and 12-month follow-up, and she was satisfied with the result.

Focus on pemphigus treatment publications: A bibliometric and visual analysis (1992-2022)

Pemphigus is a chronic recurrent disease in dermatology. Although it is not very common, its treatment has been an increasing concern in recent years because it is difficult and long-lasting. At present, there are many papers on pemphigus treatment, and to better understand the research trends and research frontiers of pemphigus treatment, it is necessary to conduct a comprehensive systematic review and analysis. We combined bibliometric and visualization methods to analyze 1365 papers published in the Web of Science database from 1992 to 2022, including basic information about countries, institutions and authors, to gain a general understanding of the treatment of pemphigus. Among them, the United States is the country with the most output, Iran's Tehran University of Medical Sciences is the institution with the most published works, and Ahmed, A. Razzaque of Tufts University is the most influential scholar. In addition, we also learned about the research hotspots and frontiers of pemphigus treatment through a series of analyses on the frequency, clustering, keywords bursts and cited literature, and we briefly reviewed the highly cited literature. We found that the current research focuses in the study of pemphigus treatment are the types, pathogenesis, and treatment of pemphigus, including glucocorticoids, immunosuppressants and many other major treatment methods. Hailey-Hailey disease, genetic susceptibility, and traditional Chinese medicine are potential research hotspots. Rituximab is a research frontier. In conclusion, we hope to provide new research ideas for promoting the development of pemphigus treatment.

Single-Cell Profiling Unveils the Inflammatory Heterogeneity within Cutaneous Lesions of Bullous Pemphigoid

Bullous pemphigoid (BP) is a subepidermal blistering skin disease with a complex pathogenesis involving various immune cells. However, the transcriptional features of these cells remain poorly defined. In this study, we constructed a comprehensive and single-cell resolution atlas of various immune cells within BP skin lesions through integrative single-cell analysis, flow cytometry, and multiplex immunohistochemistry. We observed prominent expansion and transcriptional changes in mast cells, macrophages, basophils, and neutrophils within BP lesions. Mast cells within the lesions adopted an active state and exhibited an elevated capacity for producing proinflammatory mediators. We observed an imbalance of macrophages/dendritic cells within BP lesions. Two macrophage subpopulations (NLRP3+ and C1q+) with distinct transcriptional profiles were identified and upregulated effector programs. T-peripheral helper-like T helper 2 cells were expanded in skin lesions and peripheral blood of patients with BP and were capable of promoting B-cell responses. In addition, we observed clonally expanded granzyme B-positive CD8+ T cells within BP lesions. Chemokine receptor mapping revealed the potential roles of macrophages and mast cells in recruiting pathogenic immune cells and underlying mechanisms within BP lesions. Thus, this study reveals key immune pathogenic features of BP lesions, thereby providing valuable insights for potential therapeutic interventions in this disease.

Microarray Gene Expression Analysis of Lesional Skin in Canine Pemphigus Foliaceus

Canine pemphigus foliaceus (PF) is considered the most common autoimmune skin disease in dogs; the mechanism of PF disease development is currently poorly understood. Therefore, this study aimed to characterize the molecular mechanisms and altered biological pathways in the skin lesions of canine PF patients. Using an RNA microarray on formalin-fixed, paraffin-embedded samples, we analyzed the transcriptome of canine PF lesional skin (n = 7) compared to healthy skin (n = 5). Of the 800 genes analyzed, 420 differentially expressed genes (DEGs) (p < 0.05) were found. Of those, 338 genes were significantly upregulated, including pro-inflammatory and Th17-related genes. Cell type profiling found enhancement of several cell types, such as neutrophils, T-cells, and macrophages, in PF skin compared to healthy skin. Enrichment analyses of the upregulated DEGs resulted in 78 statistically significant process networks (FDR < 0.05), including the Janus kinase signal transducer and activator of transcription (JAK-STAT) and mitogen-activated protein kinase (MAPK) signaling. In conclusion, canine PF lesional immune signature resembles previously published changes in human pemphigus skin lesions. Further studies with canine PF lesional skin using next-generation sequencing (e.g., RNA sequencing, spatial transcriptomics, etc.) and the development of canine keratinocyte/skin explant PF models are needed to elucidate the pathogenesis of this debilitating disease.

Bullous pemphigoid induced by IgG targeting type XVII collagen non-NC16A/NC15A extracellular domains is driven by Fc gamma receptor- and complement-mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting type XVII collagen (Col17) with the noncollagenous 16A (NC16A) ectodomain representing the immunodominant site. The role of additional extracellular targets of Col17 outside NC16A has not been unequivocally demonstrated. In this study, we showed that Col17 ectodomain-reactive patient sera depleted in NC16A IgG induced dermal-epidermal separation in a cryosection model indicating the pathogenic potential of anti-Col17 non-NC16A extracellular IgG. Moreover, injection of IgG targeting the murine Col17 NC14-1 domains (downstream of NC15A, the murine homologue of human NC16A) into C57BL/6J mice resulted in erythematous skin lesions and erosions. Clinical findings were accompanied by IgG/C3 deposits along the basement membrane and subepidermal blistering with inflammatory infiltrates. Disease development was significantly reduced in either Fc-gamma receptor (FcγR)- or complement-5a receptor-1 (C5aR1)-deficient mice. Inhibition of the neonatal FcR (FcRn), an atypical FcγR regulating IgG homeostasis, with the murine Fc fragment IgG2c-ABDEG, a derivative of efgartigimod, reduced anti-NC14-1 IgG levels, resulting in ameliorated skin inflammation compared with isotype-treated controls. These data demonstrate that the pathogenic effects of IgG targeting the Col17 domain outside human NC16A/murine NC15A are partly attributable to antibody-mediated FcγR- and C5aR1 effector mechanisms while pharmacological inhibition of the FcRn represents a promising treatment for BP. The mouse model of BP will be instrumental in further investigating the role of Col17 non-NC16A/NC15A extracellular epitopes and validating new therapies for this disease. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Evaluation of Dry Eye Severity and Ocular Surface Inflammation in Patients with Pemphigus and Pemphigoid

PURPOSE

To evaluate ocular surface involvement, tear cytokine levels, and histopathological changes in pemphigus and pemphigoid patients.

METHODS

A total of 22 patients (15 pemphigus and 7 pemphigoids) and 21 non-diseased controls were enrolled in our study. All participants underwent ocular surface evaluation, which included ocular surface disease index test, slit lamp observation, dry eye-related examination, tear multicytokine analysis, and conjunctival impression cytology.

RESULTS

Pemphigus and pemphigoid patients presented much more severe conjunctivochalasis, corneal epithelial defects, corneal opacity, symblepharon   and dry eye. Severe ocular surface squamous metaplasia and a significant increase of tear macrophage inflammatory protein-1beta, tumor necrosis factor-alpha, interleukin (IL)-1β, IL -6, and IL-8 occurred in pemphigus and pemphigoid patients.

CONCLUSIONS

Our results revealed that ocular surface inflammation and dry eye persist in most pemphigus and pemphigoid patients, and do not occur in parallel with the systemic course. Regular ophthalmological examinations and local anti-inflammatory should be provided for pemphigus and pemphigoid patients.

Pemphigus and pemphigoid are associated with Alzheimer's disease in older adults: evidence from the US Nationwide inpatient sample 2016-2018

BACKGROUND

Pemphigus and pemphigoid are rare autoimmune skin disorders caused by autoantibodies against structural proteins and characterized by blistering of the skin and/or mucous membranes. Associations have been noted between skin diseases and Alzheimer's dementia (AD). Dementia is a neurological disorder of progressive cognitive impairment with increasing incidence among older adults. This study aimed to assess the potential associations between pemphigus, pemphigoid and AD in a large, nationally representative US cohort.

METHODS

All data of hospitalized patients aged 60 years or older were extracted from the US Nationwide Inpatient Sample (NIS) database 2016-2018. Patients with a history of head trauma, diagnosis of vascular dementia, history of cerebrovascular disease, or malformation of cerebral vessels were excluded. The study population was divided into those with and without pemphigus (cohort 1) and with and without pemphigoid (cohort 2).

RESULTS

Pemphigus was independently associated with a 69% increased risk of AD. Adults ≥80 years old with pemphigus were 72% more likely to develop AD than adults without pemphigus. Women with pemphigus were 78% more likely to develop AD than women without pemphigus. On the other hand, pemphigoid was independently associated with a 39% increased risk for AD and subjects ≥80 years with pemphigoid were 40% more likely to have AD than those without pemphigoid. Females with pemphigoid were 63% more likely to have AD than those without pemphigoid. Moreover, Hispanic older adults with pemphigus were 3-times more likely to have AD than those without pemphigoid.

CONCLUSIONS

Pemphigus and pemphigoid were both independently associated with AD in older adults, especially among females and octogenarians. Further studies addressing the etiology and mechanisms underlying these associations are highly warranted.

Advancing Treatment in Bullous Pemphigoid: A Comprehensive Review of Novel Therapeutic Targets and Approaches

Bullous pemphigoid is one of the most common autoimmune bullous diseases occurring primarily in the elderly. Pathogenic autoantibodies against BP180 and BP230 at the dermal-epidermal junction cause subepidermal blisters, erosions, and intense pruritus, all of which adversely affect the patients' quality of life and may increase their morbidity and mortality. Current systemic treatment options for bullous pemphigoid are limited to corticosteroids and immunosuppressants, which can have substantial side effects on these vulnerable patients that even exceed their therapeutic benefits. Therefore, more precisely, targeting therapies to the pathogenic cells and molecules in bullous pemphigoid is an urgent issue. In this review, we describe the pathophysiology of bullous pemphigoid, focusing on autoantibodies, complements, eosinophils, neutrophils, proteases, and the T helper 2 and 17 axes since they are crucial in promoting proinflammatory environments. We also highlight the emerging therapeutic targets for bullous pemphigoid and their latest discoveries in clinical trials or experimental studies. Further well-designed studies are required to establish the efficacy and safety of these prospective therapeutic options.

Pemphigus and pemphigoid research by dermatologists and stomatologists: A scientometric and comparative study

Background/purpose

Pemphigus and pemphigoid are systemic bullous autoimmune diseases affecting skin and/or mucosal membranes with the life-threatening nature, especially pemphigus vulgaris. The papers published by dermatologists and stomatologists preferentially represent their concerns of a mucocutaneous disease.

Materials and methods

The objective of this study was to compare the scientometric characteristics of pemphigus and pemphigoid publications by dermatologists and stomatologists in the Scopus database.

Results

There are 9276 and 760 papers published by dermatologists and stomatologists, respectively. The annual number of the publications by dermatologists stably raised from 218 to 526 during 2007-2022; while the number by stomatologists raised with a small amount from 18 to 51 during this period. For the most-cited top-200 papers, the total citation count is 42,766 and the h index is 148 for pemphigus publications by dermatologists; whereas the count is 14,689 and h index is 63 for publications by stomatologists. Notably, first signs of pemphigus often appear in oral mucosa, manifesting as erythema, blisters, as well as mouth ulcer, gingivitis, lichen planus-like pemphigus.

Conclusion

This study firstly reports the scientometric characteristics of pemphigus publications by dermatologists and stomatologists. The scale and citations of dermatologists' publications greatly outweigh stomatologists' ones, suggesting stomatologists can learn from and more cooperate with dermatologists regarding pemphigus research.

Pemphigus vulgaris as an immune-related adverse event in recurrent metastatic esophageal squamous cell carcinoma treated with ipilimumab plus nivolumab: a case report and literature review

Ipilimumab plus nivolumab therapy is approved for patients with unresectable advanced esophageal squamous cell carcinoma (ESCC). Although a combination of immune checkpoint inhibitors (ICIs), compared to conventional chemotherapy, can improve overall survival in patients with advanced ESCC, this increases the incidence of immune-related adverse events (irAEs). Here, we describe an ESCC case that developed pemphigus vulgaris (PV), an extremely rare cutaneous irAE, during ipilimumab plus nivolumab treatment. The patient achieved a partial response to treatment. The PV was successfully managed after the cessation of ipilimumab and the use of a topical steroid. We should thus re-treat ESCC with nivolumab monotherapy. In the era of ICIs as standard cancer therapeutics, diagnostic criteria for blistering diseases need to be established to properly manage patients with cutaneous irAEs.

A case of bullous pemphigoid developing under treatment with benralizumab for bronchial asthma

Bullous pemphigoid (BP) is an autoimmune disease characterized by itchy erythema and tense blisters on the whole body. Recent reports have unveiled the pathogenic roles of eosinophils in BP (e.g., dermal-epidermal separation, generation of pruritus). Thus, eosinophils are considered a therapeutic target. Benralizumab is an anti-IL-5 receptor alpha (IL-5Rα) monoclonal antibody (mAb) that is widely used to treat severe eosinophilic asthma. By affecting IL-5Rα, benralizumab depletes eosinophils and basophils due to apoptosis through antibody-dependent cell-mediated cytotoxicity. The efficacies of benralizumab and other biologics, including bertilimumab (anti-eotaxin-1 mAb) and mepolizumab (anti-IL-5 mAb), were evaluated in several clinical trials. Also, reslizumab, an anti-IL-5 mAb, was reported as a successful treatment option in a case of BP. We present a case of severe asthma treated with benralizumab at 8-week intervals for 3 years before BP developed. Histologically, subepidermal blisters without eosinophilic infiltration were observed. Methylprednisolone pulse therapy followed by 40 mg/day (1 mg/kg/day) of oral prednisolone (PSL) was initiated, but the skin lesions worsened. Additional intravenous immunoglobulin and oral azathioprine enabled the oral PSL to be tapered. The benralizumab was discontinued after the onset of BP because the asthma did not worsen. To the best of our knowledge, there have been no reports of BP developing during anti-eosinophil therapy. BP may occur paradoxically via various pathways during treatment with drugs that are typically effective against BP.

Characterization of the serum and skin inflammatory profile in canine pemphigus foliaceus using multiplex assay and quantitative real-time polymerase chain reaction (qRT-PCR)

Canine pemphigus foliaceus (PF) is a common autoimmune skin disease characterized by autoantibodies binding to epithelial adhesion molecules resulting inflammatory response. The immune network of cytokine and chemokine abnormalities that characterize the immune response in canine PF are poorly explored. This study evaluated serum and lesional skin cytokine and chemokine profiles of dogs diagnosed with PF compared to healthy control dogs. Serum samples obtained from 11 PF dogs and 16 healthy control dogs were analyzed using commercially available canine multiplex assay for 13 biomarkers (Canine Milliplex assay). Eight lesional skin samples from seven PF dogs and five healthy site-matched samples from five healthy dogs were evaluated for 20 immune markers using quantitative real-time PCR. Immunomodulating medications were suspended for at least four weeks in all dogs before obtaining serum and skin samples. PF patients showed significantly higher serum concentrations of tumor necrosis factor-α, interleukin (IL)- 6, IL-8, IL-18, CCL2, KC-like, and granulocyte-macrophages colony-stimulating factor when compared to healthy controls (Mann-Whitney U test; p < 0.05 for all). Lesional PF skin exhibited significant expression and upregulation of pro-inflammatory/T helper (Th1) 1 markers IL-1β, MX1, GZMB, OAS1, and IFN-γ as well as Th2 cytokines IL-13, IL-33, TSLP, IL-31 and Th17/22 markers IL-17A and IL-22 (Mann-Whitney U test; p < 0.05 for all). Taken together, the findings from this study describe the role of numerous cytokines and chemokines associated with immune response in the skin and serum of canine PF patients. Further larger-sample proteomics and RNA-sequencing transcriptomics studies are needed to understand the immune pathogenesis of canine PF skin lesions.

Architecture and dynamics of a desmosome-endoplasmic reticulum complex

The endoplasmic reticulum (ER) forms a dynamic network that contacts other cellular membranes to regulate stress responses, calcium signalling and lipid transfer. Here, using high-resolution volume electron microscopy, we find that the ER forms a previously unknown association with keratin intermediate filaments and desmosomal cell-cell junctions. Peripheral ER assembles into mirror image-like arrangements at desmosomes and exhibits nanometre proximity to keratin filaments and the desmosome cytoplasmic plaque. ER tubules exhibit stable associations with desmosomes, and perturbation of desmosomes or keratin filaments alters ER organization, mobility and expression of ER stress transcripts. These findings indicate that desmosomes and the keratin cytoskeleton regulate the distribution, function and dynamics of the ER network. Overall, this study reveals a previously unknown subcellular architecture defined by the structural integration of ER tubules with an epithelial intercellular junction.

Interleukin-36 cytokines are overexpressed in the skin and sera of patients with bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune bullous disease, characterized by autoantibodies targeting BP180 and BP230. The role of interleukin (IL)-36, a potent chemoattractant for granulocytes, in BP remains elusive.The expression of IL-36 cytokines (IL-36α, β, γ) and their antagonists (IL-36Ra and IL-38) was analysed in the skin and serum samples of patients with BP (n = 31), psoriasis (n = 10) and healthy controls (HC) (n = 14) by quantitative polymerase chain reaction and enzyme linked immunosorbent assay, respectively. Skin and serum levels of all cytokines were correlated with the Bullous Pemphigoid Disease Area Index (BPDAI) score and with the serum concentration of pathogenic antibodies.IL-36α, IL-36β, IL-36γ and IL-36Ra were significantly (p < 0.05) overexpressed in BP skin compared to HC, without remarkable differences relative to psoriasis skin. The expression of IL-38 was significantly (p < 0.05) higher in BP compared to psoriasis skin.IL-36α and γ, but not β, serum concentrations were significantly (p < 0.05) higher in BP compared to HC. IL-36γ was significantly (p < 0.05) more expressed in the serum of psoriasis patients than BP. The serum concentration of IL-36Ra and IL-38 were similar between BP and HC, while IL-38 serum levels were significantly (p < 0.05) higher in BP compared to psoriasis patients. Serum IL-36α correlated significantly with BPDAI (r = 0.5 p = 0.001).IL-36 agonists are increased in BP patients, both locally and systemically. Serum IL-36α might represent a potential biomarker for BP. An inefficient balance between IL-36 agonists and antagonists is likely to occur during BP inflammation.

The cytokine milieu of bullous pemphigoid: Current and novel therapeutic targets

Bullous pemphigoid (BP) is the most common autoimmune bullous disease, characterized by severe pruritus and skin blistering. The loss of tolerance against Collagen XVII, also referred to as BP180, is the main pathogenic event of BP, leading to production of IgG autoantibodies which mainly target the juxtamembranous extracellular non-collagenous 16th A (NC16A) domain of BP180. A complex inflammatory network is activated upon autoantibody binding to the basement membrane zone; this inflammatory loop involves the complement cascade and the release of several inflammatory cytokines, chemokines and proteases from keratinocytes, lymphocytes, mast cells and granulocytes. Collectively, these events disrupt the integrity of the dermal-epidermal junction, leading to subepidermal blistering. Recent advances have led to identify novel therapeutic targets for BP, whose management is mainly based on the long-term use of topical and systemic corticosteroids. As an example, targeting type-2 T-helper cell-associated cytokines, such as Interleukin-4 and interleukin-13 has shown meaningful clinical efficacy in case series and studies; targeting IL-17 and IL-23 has also been tried, owing to an important role of these cytokines in the chronic maintenance phase of BP. In this review article, we discuss the complex cytokine milieu that characterized BP inflammation, highlighting molecules, which are currently investigated as present and future therapeutic targets for this life-threatening disease.

Mouse models of pemphigus: valuable tools to investigate pathomechanisms and novel therapeutic interventions

Autoimmune blistering diseases (AIBD) are paradigms of autoantibody-mediated organ-specific autoimmune disorders that involve skin and/or mucous membranes. Compared to other autoimmune diseases, the pathogenicity of autoantibodies in AIBD is relatively well described. Pemphigus is a potentially lethal autoantibody driven autoimmune disorder with a strong HLA class II association. It is mainly characterized by IgG against the desmosomal adhesion molecules desmoglein 3 (Dsg3) and Dsg1. Several murine pemphigus models were developed subsequently, each allowing the analysis of a characteristic feature, such as pathogenic IgG or Dsg3-specific T or B cells. Thus, the models can be employed to preclinically evaluate potentially novel therapies. We here thoroughly summarize past and recent efforts in developing and utilizing pemphigus mouse models for pathomechanistic investigation and therapeutic interventions.

Dipeptidyl Peptidase-4 Inhibitor-Related Bullous Pemphigoid: Clinical, Laboratory, and Histological Features, and Possible Pathogenesis

Dipeptidyl peptidase-4 inhibitor (DPP4i) is a widely used antidiabetic agent. Emerging cases of DPP4i-associated bullous pemphigoid (DBP), whose pathogenesis remains unclear, have been reported. Thus, a retrospective study was conducted from January 2016 to June 2021 to determine the clinical, laboratory, and histopathological features of DBP and idiopathic bullous pemphigoid (IBP). We set up in vitro experiments using vildagliptin-treated HaCaT keratinocytes to validate what we found by analyzing published RNA sequencing data about the genes related to the dermal-epidermal junction. We also observed IL-6 expression by HaCaT cells treated with vildagliptin. We enrolled 20 patients with DBP and 40 patients with IBP. The total Bullous Pemphigoid Disease Area Index (BPDAI) score was similar in both groups. However, the BPDAI score of erosions and blisters in DBP was significantly higher than that in IBP (24.6 vs. 16.68, p = 0.0189), and the score for urticaria and erythema was lower in DBP (12 vs. 19.05, p = 0.0183). The pathological features showed that the mean infiltrating eosinophil number per high-power field was significantly lower in DBP than in IBP (16.7 vs. 27.08, p = 0.023). The expression of LAMA3, LAMB3, LAMC2, DST, and COL17A1 decreased significantly in vildagliptin-treated human keratinocytes. On the other hand, IL-6, the hallmark cytokine of bullous pemphigoid (BP) severity, was found to be upregulated in HaCaT cells by vildagliptin. These experimental findings imply less of a requirement for eosinophil infiltration to drive the inflammatory cascades in DBP blistering. Both immunologic and non-immunologic pathways could be employed for the development of DBP. Our findings may help explain the higher incidence of non-inflammatory BP that was observed in DBP.

Immunotherapy for Pemphigus: Present and Future

Pemphigus is a chronic and severe autoimmune bullous disease caused by autoantibodies targeting adhesion molecules between keratinocytes. It requires 2–3 years on average to manage the disease. To date, although Rituximab combined with short-term systemic glucocorticoids was accepted as first-line therapy, systemic glucocorticoids remain the primary therapeutic option for pemphigus patients, successfully decreasing morbidity and mortality from pemphigus. However, novel therapeutic strategies are desirable due to the low efficacy in some subset of patients and the long-term severe adverse effects of traditional therapies. Recently, immunotherapy has proved to be encouraging for disease control or cure. Based on the current understanding of the immune mechanisms of pemphigus, we review the immune targets and corresponding agents applied in practice or under clinical trials. The goals of the novel treatments are to improve the quality of life of pemphigus patients by improving efficacy and safety, minimizing side effects, achieving fast disease control, or curing the disease.

Mechanisms Causing Acantholysis in Pemphigus-Lessons from Human Skin

Pemphigus vulgaris (PV) is an autoimmune bullous skin disease caused primarily by autoantibodies (PV-IgG) against the desmosomal adhesion proteins desmoglein (Dsg)1 and Dsg3. PV patient lesions are characterized by flaccid blisters and ultrastructurally by defined hallmarks including a reduction in desmosome number and size, formation of split desmosomes, as well as uncoupling of keratin filaments from desmosomes. The pathophysiology underlying the disease is known to involve several intracellular signaling pathways downstream of PV-IgG binding. Here, we summarize our studies in which we used transmission electron microscopy to characterize the roles of signaling pathways in the pathogenic effects of PV-IgG on desmosome ultrastructure in a human ex vivo skin model. Blister scores revealed inhibition of p38MAPK, ERK and PLC/Ca2+ to be protective in human epidermis. In contrast, inhibition of Src and PKC, which were shown to be protective in cell cultures and murine models, was not effective for human skin explants. The ultrastructural analysis revealed that for preventing skin blistering at least desmosome number (as modulated by ERK) or keratin filament insertion (as modulated by PLC/Ca2+) need to be ameliorated. Other pathways such as p38MAPK regulate desmosome number, size, and keratin insertion indicating that they control desmosome assembly and disassembly on different levels. Taken together, studies in human skin delineate target mechanisms for the treatment of pemphigus patients. In addition, ultrastructural analysis supports defining the specific role of a given signaling molecule in desmosome turnover at ultrastructural level.