Pemphigus

Prognostic Factors Predicting Remission Following Rituximab Therapy for Pemphigus Vulgaris

Pemphigus vulgaris is a chronic autoimmune blistering disease with significant morbidity. Rituximab, approved as its first-line treatment, effectively induces remission. However, few studies have analysed the prognostic factors for improved rituximab outcomes. Therefore, this study aimed to identify such factors in a cohort of pemphigus vulgaris patients. A total of 142 pemphigus vulgaris patients treated with rituximab at Sheba Medical Center, with data encompassing demographics, comorbidities, disease characteristics, and treatment outcomes, were retrospectively examined. Results showed that 61.9% of patients previously treated with mycophenolate mofetil achieved partial remission, whereas only 34.7% achieved complete remission. Patients with diabetes mellitus exhibited a significantly shorter median time to relapse compared with those without. Patients with a disease duration ≤ 16 months before rituximab therapy exhibited a shorter median time to relapse. Moreover, previous dapsone treatment extended time to relapse. Notably, sex, age at symptom onset and rituximab therapy, ethnicity, comorbidities, skin involvement, weight, rituximab dosing protocol, and other variables were not statistically significant between the complete remission and partial remission groups. These findings highlight the influence of specific patient characteristics and treatment histories on response to rituximab and time to relapse in pemphigus vulgaris patients. Understanding these factors can aid clinicians in predicting treatment outcomes and selecting the appropriate patient population for rituximab therapy.

Evaluation of link between COVID-19 adjacent spike in hydroxychloroquine use and increased reports of pemphigus: a disproportionality analysis of the FDA Adverse Event Reporting System

Importance

Identifying environmental factors that contribute to disease onset/activity in PV stands to improve clinical outcomes and patient quality of life by strategies aimed at reducing specific disease promoting exposures and promoting personalized clinical management strategies.

Objective

To evaluate the association between hydroxychloroquine use and the development of pemphigus using population level, publicly available, FDA-generated data.

Design

Observational, retrospective, case-control, pharmacovigilance analysis.

Setting

Population based.

Participants

Individuals who either independently or via their healthcare provider submitted a voluntary report of a drug related adverse event to the FDA from Q4 of 2003 to Q2 of 2023.

Exposure

Cases were identified by the presence of adverse events described by the MedDRA preferred term (PT) of "pemphigus" (10034280) and then sorted based on exposure to the drug of interest, hydroxychloroquine, or lack thereof.

Main outcomes and measures

Frequency of hydroxychloroquine exposure among those individuals who reported an adverse event of pemphigus to the FDA; quantification of the reporting odds ratio (ROR).

Results

We identified a total of 2,548 reports that included the adverse event pemphigus; among these, 1,545 (n=706 (41.92%) age 18-64, n=1 age 65-85 years, and n=977 (58.02%) with no age specified; n=1,366 (81.12%) females, n=4 (0.24%) males, and n=314 (18.65%) with no gender specified) included exposure to hydroxychloroquine (ROR, 282.647; 95% CI, 260.951-306.148). We then stratified those reports that included the combination of pemphigus and hydroxychloroquine by gender and found that while the association between the exposure and adverse event remained significant across genders, the magnitude of the effect sizes differed significantly (p<0.001), being over 100-fold greater among females (ROR, 378.7; 95% CI, 339.0-423.1) compared to males (ROR, 3.6; 95% CI, 1.4-9.8).

Conclusions and relevance

The frequency of reports containing the combination of the adverse event pemphigus and exposure to the drug hydroxychloroquine was disproportionately elevated across all genders in the years since the start of the COVID-19 pandemic. The disproportionately elevated frequency of reports of the combination of pemphigus and hydroxychloroquine supports an association between the two, corroborates previous case-report based evidence for such an association, suggests that hydroxychloroquine represents a possible trigger factor for the development of pemphigus, and paves the way for future research that is capable of establishing causality.

FcRn inhibitors: Transformative advances and significant impacts on IgG-mediated autoimmune diseases

Pathogenic IgG autoantibodies play a crucial role in the pathogenesis of autoimmune diseases, and removal of pathogenic IgG autoantibodies is an important therapeutic approach and tool for such diseases. The neonatal Fc receptor (FcRn) interacts with IgG and protects it from lysosomal degradation. FcRn inhibitors accelerate the clearance of IgG antibodies, including pathogenic IgG autoantibodies, by targeting and blocking the binding of FcRn to IgG. Theoretically, FcRn inhibitors can be applied for the treatment of IgG-mediated autoimmune diseases. With successful completion of multiple relevant clinical trials, key evidence-based data have been provided for FcRn inhibitors in the treatment of IgG-mediated autoimmune diseases, and several FcRn inhibitors have been approved for these indications. Additional trials are being planned or conducted. This review examines all available high-quality clinical trials of FcRn inhibitors assessing IgG-mediated autoimmune diseases.

HDAC1-mediated regulation of KDM1A in pemphigus vulgaris: unlocking mechanisms on ERK pathway activation and cohesion loss

Pemphigus vulgaris (PV) is an autoimmune skin disorder characterized by the loss of cell cohesion, with the histone deacetylase 1 (HDAC1) and lysine demethylase 1A (KDM1A) playing critical roles in its pathogenesis. This study aimed to elucidate the molecular mechanisms behind PV, focusing on the function of HDAC1 and KDM1A in disease onset and progression. Based on in vitro and in vivo PV models, we observed a significant increase in HDAC1 mRNA and protein levels in skin tissues of PV patients. Inhibition of HDAC1 ameliorated cell damage and reduced the loss of cell cohesion in human epidermal keratinocytes (HEKs) induced by PV-IgG. Our findings suggest that HDAC1 regulates KDM1A expression through deacetylation, with a notable deficiency in KDM1A expression in PV. Overexpression of KDM1A mitigated cell damage and cohesion loss. The extracellular signal-regulated kinase (ERK) pathway serves as a downstream executor of the HDAC1/KDM1A axis. Inhibiting HDAC1 and increasing KDM1A expression suppressed ERK phosphorylation, reducing PV-related apoptosis. These insights provide a new perspective on treating PV, highlighting the therapeutic potential of targeting HDAC1 expression. The regulatory mechanism of the HDAC1/KDM1A/ERK axis offers crucial clues for understanding PV pathogenesis and developing novel treatments.

Large-scale global retrospective study on the interaction between ancestry and risk of comorbid autoimmune diseases in patients with pemphigus

The pemphigus family of skin blistering diseases represents a rare yet potentially life-threatening condition characterized by multiple known genetic loci associated with other autoimmune disorders. While several studies have empirically indicated an increased risk of developing additional autoimmune diseases in individuals with pemphigus, the scarcity of data and the rarity of pemphigus have hindered efforts to establish and generalize these associations across diverse populations. In this study, we analyzed a dataset comprising 126 million patients, including 18,000 with pemphigus, to assess the likelihood of developing any of 74 autoimmune diseases following a diagnosis of pemphigus. For a subset of 26 diseases from this list with adequate patient numbers, we conducted further case-control retrospective analyses to quantify the odds and hazard ratios of developing comorbid conditions across various ethnicities. Our findings reveal highly significant and generalizable associations between pemphigus and pemphigoid diseases, discoid lupus erythematosus, lichen planus, and undifferentiated connective tissue disease, among others.

Mild cognitive impairment in pemphigus

BACKGROUND

Pemphigus is a group of autoimmune blistering disorders that have been associated with dementia in previous studies. Mild cognitive impairment (MCI) can be the first stage of progression into dementia. The objective of the present study was to evaluate the frequency of MCI in pemphigus patients compared to a control group.

METHODS

This case-control study included 80 patients with pemphigus referred to the dermatology clinics of Shohadaye Tajrish and Loghman Hakim hospitals, Tehran, Iran, in 2021. A group of 80 individuals without pemphigus who visited the same clinics for cosmetic consultation or interventions were regarded as controls. Age, sex, marital status, and education were recorded for all participants. Disease duration, medications, and severity were noted for pemphigus patients. The Persian version of the Montreal Cognitive Assessment (MoCA) test was used to assess cognitive function.

RESULTS

MCI was significantly more frequent in pemphigus patients than in controls (55% vs. 37.5%, P = 0.026). Furthermore, the total MoCA score was significantly lower in pemphigus patients compared to controls (23.98 ± 3.77 vs. 25.21 ± 3.45, P = 0.032); however, among MoCA's different domains, only the executive functions score was significantly lower in pemphigus patients (P = 0.010). After adjustment, multivariable logistic regression analysis revealed that every 1-year higher education in patients decreased the odds of MCI by 52% (adjusted odds ratio = 0.483, 95% confidence interval 0.326; 0.715, P < 0.001).

CONCLUSIONS

The frequency of MCI was found to be significantly higher, and overall scores of the MoCA test, as well as its executive function domain, were significantly lower among pemphigus patients in this study compared to the control group. Additionally, a higher level of education was associated with decreased odds of MCI in pemphigus patients. Identifying pemphigus patients with MCI through the use of the MoCA test can facilitate early intervention, enabling them to seek help and support.

The efficacy and safety of low-dose rituximab in the treatment of pemphigus vulgaris: a cohort study

BACKGROUND

Rituximab (RTX) is considered the first-line treatment for pemphigus vulgaris (PV), which is a B-cell-mediated acquired autoimmune disease. However, no consensus on the optimum dosage has been achieved.

OBJECTIVES

To investigate the efficacy and safety of low-dose RTX (a single infusion of 500 mg) for the treatment of PV, a cohort study was conducted for patients with PV, along with a 12-month follow-up following the administration of RTX.

METHODS

Patients with moderate or severe PV were divided into group A (low-dose RTX combined with corticosteroids) and group B (corticosteroids alone). Data on complete remission (CR) rates, doses of corticosteroids, cumulative doses of corticosteroids at the third, sixth, and twelfth months, pemphigus disease area index and adverse effects (AEs) were collected.

RESULTS

Forty-four patients with moderate or severe PV were enrolled in this study (19 in group A and 25 in group B). Patients treated with low-dose RTX had higher CR rates, lower doses of corticosteroids at the third, sixth, and twelfth months, lower cumulative doses of corticosteroids at the sixth and twelfth months, and fewer AEs than those who received corticosteroids alone.

CONCLUSIONS

This study indicated that low-dose RTX may be a beneficial and secure therapy option for patients with moderate to severe PV.

Effect of opioid receptor antagonist on mitigating tumor necrosis factor-like weak inducer of apoptosis (TWEAK)-induced apoptolysis in pemphigus pathogenesis

Pemphigus is a severe autoimmune blistering disease characterized by acantholysis triggered by autoantibodies against desmoglein 1 and 3 (DSG1/3). Apoptosis plays a pivotal role in facilitating acantholysis, yet the precise underlying mechanism remains obscure. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is known to promote apoptosis and disrupt cell junctions, although its involvement in pemphigus pathogenesis remains ambiguous. Our study observed decreased DSG1/3 expression alongside increased TWEAK/fibroblast growth factor-inducible 14 (Fn14) expression and keratinocyte apoptosis in both lesional and perilesional skin. In vitro experiments revealed that TWEAK-stimulated keratinocytes exhibited enhanced apoptosis, STAT1 phosphorylation, and reduced intercellular DSG1/3 expression. Notably, bulk-RNA sequencing unveiled that CASPASE-3 was responsible for mediating the DSG1/3 depletion, as confirmed by direct interaction with DSG1/3 in a co-immunoprecipitation assay. Naloxone, known for preserving cellular adhesion and preventing cell death, effectively reduced apoptosis and restored DSG1/3 levels in TWEAK-stimulated keratinocytes. The anti-apoptotic properties of naloxone were further validated in a murine pemphigus model. Our findings elucidate that TWEAK facilitates keratinocyte apoptosis by augmenting caspase-3 activity, leading to DSG1/3 depletion and apoptosis in pemphigus. Importantly, naloxone can counter TWEAK-induced apoptosis in pemphigus pathogenesis, offering a potential therapeutic intervention.

Coexistence of Pemphigus Foliaceus and Bullous Pemphigoid: A Case Report

Pemphigus foliaceus (PF) and bullous pemphigoid (BP) are distinct autoimmune bullous skin diseases mediated by autoantibodies targeting adhesion molecules in desmosomes and hemidesmosomes structural proteins in the epidermal-basement membrane zone, respectively. The coexistence of PF and BP is rare. We present the case of a 72-year-old male with clinical and histological features of both PF and BP. Treatment with immunoglobulin (10 g/day for 3 days), intravenous dexamethasone sodium phosphate (5 mg/day for 10 days), oral triamcinolone (30 mg/day for 10 days), and minocycline hydrochloride (20 mg/day for 10 days) resulted in significant improvement. This rare case highlights the importance of accurate diagnosis and effective treatment strategies for the coexistence of PF and BP.

Topographical variations in the skin barrier and their role in disease pathogenesis

The skin barrier can be divided into at least four functional units: chemical, microbial, physical and immunological barriers. The chemical and microbial barriers have previously been shown to exhibit different characteristics in topographically distinct skin regions. There is increasing evidence that the physical and immunological barriers also show marked variability in different areas of the skin. Here, we review recent data on the topographical variations of skin barrier components, the contribution of these variations to the homeostatic function of the skin and their impact on the pathogenesis of specific immune-mediated skin diseases (such as atopic dermatitis and papulopustular rosacea). Recognition of these topographical barrier differences will improve our understanding of skin homeostasis and disease pathogenesis and provide a basis for body site-specific targeted therapies.

Conjoint analysis of methylation, transcriptomic, and proteomic profiles in pemphigus vulgaris

BACKGROUND

The underlying pathogenesis of pemphigus vulgaris, an autoimmune skin disorder, remains incompletely understood. An integrative analysis comprising DNA methylation, mRNA expression, and proteomic data in patients with pemphigus vulgaris was conducted to identify potential pathogenic contributors and explore the molecular mechanisms involved in its pathogenesis.

RESULTS

The analysis revealed differentially methylated regions (DMRs) in the promoter, exon, intron, and downstream regions in the peripheral blood DNA of patients with pemphigus vulgaris. Associations between methylation levels and both transcriptomic and proteomic profiles revealed that differentially expressed genes between patients with pemphigus vulgaris and healthy controls were primarily linked to biological functions such as platelet activation and coagulation, cellular adhesion, and immunoglobulin binding. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis highlighted notable pathway abnormalities, including those related to platelet activation, focal adhesions, tight junctions, and infectious inflammatory responses. Notably, genes such as FGA (fibrinogen alpha chain), VWF (von Willebrand factor), and ACTG1 (actin gamma 1) were dysregulated, with a prominent role in platelet activation.

CONCLUSION

The dysregulation of genes such as FGA, VWF, and ACTG1 suggests that alterations in their transcription and expression may contribute to the pathogenesis of pemphigus vulgaris.

Autoimmune disease: a view of epigenetics and therapeutic targeting

Autoimmune diseases comprise a large group of conditions characterized by a complex pathogenesis and significant heterogeneity in their clinical manifestations. Advances in sequencing technology have revealed that in addition to genetic susceptibility, various epigenetic mechanisms including DNA methylation and histone modification play critical roles in disease development. The emerging field of epigenetics has provided new perspectives on the pathogenesis and development of autoimmune diseases. Aberrant epigenetic modifications can be used as biomarkers for disease diagnosis and prognosis. Exploration of human epigenetic profiles revealed that patients with autoimmune diseases exhibit markedly altered DNA methylation profiles compared with healthy individuals. Targeted cutting-edge epigenetic therapies are emerging. For example, DNA methylation inhibitors can rectify methylation dysregulation and relieve patients. Histone deacetylase inhibitors such as vorinostat can affect chromatin accessibility and further regulate gene expression, and have been used in treating hematological malignancies. Epigenetic therapies have opened new avenues for the precise treatment of autoimmune diseases and offer new opportunities for improved therapeutic outcomes. Our review can aid in comprehensively elucidation of the mechanisms of autoimmune diseases and development of new targeted therapies that ultimately benefit patients with these conditions.

Laboratory and clinical haemostatic aberrations in primary dermatologic disease: A review

Inflammatory dermatologic diseases have long been viewed as a "skin limited" disease process. Current literature on inflammatory dermatologic diseases investigates their relationship and influence on thromboembolic states and thromboembolic complications and the understanding of their pathophysiology and molecular mechanisms.Studies specifically discuss known inflammatory skin diseases including alopecia areata, vitiligo, psoriasis, hidradenitis suppurativa, atopic dermatitis, chronic spontaneous urticaria, and autoimmune bullous diseases, and their effects on systemic inflammation, associated cardiovascular comorbidities, and thromboembolic or hypercoagulable states. The limited current literature shows potential for links between inflammatory skin diseases and hypercoagulable states. Biomarkers such as F1 + 2, D-dimer, eosinophilic cationic protein, and PAI-1 are currently being studied to outline the mechanisms connecting inflammatory skin disease to the coagulation system. Further study and larger amounts of data are needed to draw definitive conclusions, especially when interpreting biomarkers alone such as PAI-1.The mechanisms, rates of systemic inflammation, and clinical outcomes of traditionally "skin limited" inflammatory diseases remain chronically understudied in dermatology. Many organ systems have well established connections between inflammatory disease and hypercoagulable states, but there are significant gaps in the literature regarding skin diseases. There is a significant need for comprehensive investigation of molecular mechanisms behind inflammatory dermatologic disease and hypercoagulability, how hypercoagulability effects clinical outcomes, and proper intervention to optimize patient outcomes.

Oral lichen planus-like lesions in skin of color: a review

In dermatology, lichenoid describes lesions with a violaceous hue that is a clinical reflection of basal cell damage in the epithelium and dense mononuclear infiltrate in the sub-epithelium. The violaceous color results from pigment incontinence due to basal cell damage and the Tyndall effect. Although classically described in lichen planus, a lichenoid hue is noted in the oral mucosa in several other disorders that often lead to diagnostic dilemmas. Early and accurate diagnosis is important for the appropriate management of the underlying condition and prognostication. Dermatologists play a central role in managing such patients since, apart from the oral mucosa findings, the cutaneous features also help to significantly differentiate various conditions. Mimickers of oral lichen planus include nicotine stomatitis, oral submucous fibrosis, oral lichenoid lesions, mucosal discoid lupus erythematosus, pemphigus vulgaris, paraneoplastic pemphigus, mucous membrane pemphigoid, fixed drug eruption, plasma cell cheilitis/gingivitis, and erythema multiforme. While a detailed history and clinical examination can help reach a diagnosis in most cases, histopathology, immunofluorescence, and other relevant investigations help establish the diagnosis.

EGFR Inhibition by Erlotinib Rescues Desmosome Ultrastructure and Keratin Anchorage and Protects against Pemphigus Vulgaris IgG-Induced Acantholysis in Human Epidermis

Pemphigus is a severe blistering disease caused by autoantibodies primarily against the desmosomal cadherins desmoglein (DSG)1 and DSG3, which impair desmosome integrity. Especially for the acute phase, additional treatment options allowing to reduce corticosteroids would fulfill an unmet medical need. In this study, we provide evidence that EGFR inhibition by erlotinib ameliorates pemphigus vulgaris IgG-induced acantholysis in intact human epidermis. Pemphigus vulgaris IgG caused phosphorylation of EGFR (Y845) and Rous sarcoma-related kinase in human epidermis. In line with this, a phosphotyrosine kinome analysis revealed a robust response associated with EGFR and Rous sarcoma-related kinase family kinase signaling in response to pemphigus vulgaris IgG but not to pemphigus foliaceus autoantibodies. Erlotinib inhibited pemphigus vulgaris IgG-induced epidermal blistering and EGFR phosphorylation, loss of desmosomes, as well as ultrastructural alterations of desmosome size, plaque symmetry, and keratin filament insertion and restored the desmosome midline considered as hallmark of mature desmosomes. Erlotinib enhanced both single-molecule DSG3-binding frequency and strength and delayed DSG3 fluorescence recovery, supporting that EGFR inhibition increases DSG3 availability and cytoskeletal anchorage. Our data indicate that EGFR is a promising target for pemphigus therapy owing to its link to several signaling pathways known to be involved in pemphigus pathogenesis.

Establishing minimal clinically important differences for the Pemphigus Disease Area Index

BACKGROUND

Pemphigus is a rare autoimmune blistering disease with potentially life-threatening consequences. Establishing minimal clinically important differences (MCIDs) for disease severity scores like the Pemphigus Disease Area Index (PDAI) is crucial for assessing treatment efficacy.

OBJECTIVES

To calculate MCIDs for both improvement and deterioration in PDAI scores in patients with pemphigus vulgaris (PV) and pemphigus foliaceus (PF), using the anchor-based method.

METHODS

A total of 41 patients with pemphigus were recruited, with 35 meeting the MCID analysis criteria. The anchor-based method was used to calculate MCIDs for PDAI scores against the 15-point Likert scale and the Physician Global Assessment visual analogue scale (PGA-VAS) anchors. Receiver operating characteristic curves were employed to determine optimal MCID cutpoints with the highest Youden Index (J). The 15-point Likert scale scores the change in disease severity spanning from -7 to +7, designed to quantify the extent of disease improvement/deterioration since the preceding visit.

RESULTS

The MCID for improvement in PDAI activity scores was 2.65 points using the 15-point Likert scale (78.7% correct classification; sensitivity 75.9%; specificity 73.5%) and 2.5 points using the PGA-VAS as the anchor (78.0% correct classification; sensitivity 84.4%; specificity 68.2%). Given the slightly higher correct classification rate using the 15-point Likert scale anchor, the MCID of 2.65 points was selected for PDAI activity score improvement. In contrast, the MCID for deterioration consistently remained at 2.5 points for the 15-point Likert scale anchor (81.0% correct classification; sensitivity 72.7%; specificity 81.0%) and 2.5 points for the PGA-VAS anchor (70.9% correct classification; sensitivity 69.6%; specificity 76.9%).

CONCLUSIONS

This study marks the inaugural attempt at MCID determination for PDAI scores in pemphigus, filling a critical knowledge gap. The study's calculated MCIDs provide essential benchmarks for clinical trials, treatment evaluation and research design optimization. Future studies should explore international collaborations, to examine potential cross-cultural variations in MCIDs.

Association of four CTLA-4 gene polymorphisms with pemphigus risk: a systematic review, meta-analysis, and meta-regression

OBJECTIVES

This review aimed to summarize the existing data on the contribution of four single nucleotide polymorphisms (SNPs) in the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) genes to pemphigus susceptibility.

METHODS

An electronic literature search for eligible studies among those published prior to 30 April 2024 was conducted through the PubMed, EMBASE, Web of Science, and Scopus databases. To minimize publication bias, an additional search was performed via the Google Scholar and Semantic Scholar search engines. Meta-analyses, together with subgroup analyses and meta-regressions, were performed for the following four CTLA-4 SNPs: rs231775, rs5742909, rs3087243, and rs733618.

RESULTS

Combined analyses revealed a significant increase in pemphigus risk conferred by the CTLA-4 rs5742909*C and rs733618*C alleles. Conversely, there was no evidence of any significant association between the rs231775*G and rs3087243*G alleles and susceptibility to pemphigus. Subgroup analyses by ethnicity and pemphigus type (vulgaris or foliaceus) and meta-regressions did not reveal any significant difference.

CONCLUSION

This meta-analysis suggested that two of the four investigated CTLA-4 SNPs were significantly associated with increased pemphigus risk.Registration: This review has been registered on PROSPERO: CRD42024550668; available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024550668.

Proteomic Analysis Reveals Oxidative Phosphorylation and JAK-STAT Pathways Mediated Pathogenesis of Pemphigus Vulgaris

Pemphigus vulgaris (PV) stands as a rare autoimmune bullous disease, while the precise underlying mechanism remains incompletely elucidated. High-throughput proteomic methodologies, such as LC-MS/MS, have facilitated the quantification and characterisation of proteomes from clinical skin samples, enhancing our comprehension of PV pathogenesis. The objective of this study is to elucidate the signalling mechanisms underlying PV through proteomic analysis. Proteins and cell suspension were extracted from skin biopsies obtained from both PV patients and healthy volunteers and subsequently analysed using LC-MS/MS and scRNA-seq. Cultured keratinocytes were treated with PV serum, followed by an assessment of protein expression levels using immunofluorescence and western blotting. A total of 880, 605, and 586 differentially expressed proteins (DEPs) were identified between the lesion vs. control, non-lesion vs. control, and lesion vs. non-lesion groups, respectively. The oxidative phosphorylation (OXPHOS) pathway showed activation in PV. Keratinocytes are the major cell population in the epidermis and highly expressed ATP5PF, ATP6V1G1, COX6B1, COX6A1, and NDUFA9. In the cellular model, there was a notable increase in the expression levels of OXPHOS-related proteins (V-ATP5A, III-UQCRC2, II-SDHB, I-NDUFB8), along with STAT1, p-STAT1, and p-JAK1. Furthermore, both the OXPHOS inhibitor metformin and the JAK1 inhibitor tofacitinib demonstrated therapeutic effects on PV serum-induced cell separation, attenuating cell detachment. Metformin notably reduced the expression of V-ATP5A, III-UQCRC2, II-SDHB, I-NDUFB8, p-STAT1, p-JAK1, whereas tofacitinib decreased the expression of p-STAT1 and p-JAK1, with minimal impact on the expression of V-ATP5A, III-UQCRC2, II-SDHB, and I-NDUFB8. Our results indicate a potential involvement of the OXPHOS and JAK-STAT1 pathways in the pathogenesis of PV.

The emergence of circulating activated autoreactive desmoglein 3-specific follicular regulatory T cells is associated with long-term efficacy of rituximab in patients with pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV) is characterized by autoantibodies targeting keratinocyte adhesion proteins desmoglein (Dsg) 1 and 3, and by the human leukocyte antigen (HLA) predisposition allele HLA-DRB1*0402. Treatment using rituximab (RTX) combined with short-term corticosteroids (CS) allows disease control and long-lasting remission.

OBJECTIVES

The principal aim of this study was to evaluate the impact of RTX on the circulating subpopulations of Dsg3-specific T lymphocytes that specifically regulate B-cell responses: follicular helper T (Tfh) and follicular regulatory T (Tfr) lymphocytes.

METHODS

Using the HLA-DRB1*0402 tetramer loaded with the Dsg3 immunodominant peptide, we used flow cytometry to analyse the frequency, polarization and activation status of blood Dsg3-specific follicular T-cell populations at baseline, month (M) 6 and long-term follow-up (M60-90) from patients with PV.

RESULTS

At baseline, we observed a predominance of Tfh1* and Tfh17 subsets and an underrepresentation of the Tfh2 subset among autoreactive Dsg3-specific Tfh cells compared with nonautoreactive Tfh cells. RTX treatment induced a decrease of autoreactive Tfh cells with no effect on their polarization during follow-up. In parallel, we observed the emergence of a Dsg3-specific Tfr subpopulation with a significant overexpression of the surface activation markers PD1, ICOS and CD25 that was not observed at the surface of autoreactive Tfh and nonautoreactive Tfr cells of the same patients with PV. In contrast, very few Dsg3-specific Tfr cells were observed in patients with PV who were treated with CS alone.

CONCLUSIONS

Here we show that the emergence of circulating autoreactive Dsg3-specific Tfr cells is associated with the long-term efficacy of RTX in patients with PV.

GRAPHICAL ABSTRACT

The RhoGAP ARHGAP32 interacts with desmoplakin, and is required for desmosomal organization and assembly

Desmosomes play a crucial role in maintaining tissue barrier integrity, particularly in mechanically stressed tissues. The assembly of desmosomes is regulated by the cytoskeleton and its regulators, and desmosomes also function as a central hub for regulating F-actin. However, the specific mechanisms underlying the crosstalk between desmosomes and F-actin remain unclear. Here, we identified that ARHGAP32, a Rho GTPase-activating protein, is located in desmosomes through its interaction with desmoplakin (DSP) via its GAB2-interacting domain (GAB2-ID). We confirmed that ARHGAP32 is required for desmosomal organization, maturation and length regulation. Notably, loss of ARHGAP32 increased formation of F-actin stress fibers and phosphorylation of the regulatory myosin light chain Myl9 at T18/S19. Inhibition of ROCK activity in ARHGAP32-knockout (KO) cells effectively restored desmosomal organization and the integrity of epithelial cell sheets. Moreover, loss of DSP impaired desmosomal ARHGAP32 location and led to decreased actomyosin contractility. ARHGAP32 with a deletion of the GAB2-ID domain showed enhanced association with RhoA in the cytosol and failed to rescue the desmosomal organization in ARHGAP32-KO cells. Collectively, our study unveils that ARHGAP32 associates with and regulates desmosomes by interacting with DSP. This interaction potentially facilitates the crosstalk between desmosomes and F-actin.

Epidemiological Insights into Autoimmune Bullous Diseases in China: A Comprehensive Analysis

OBJECTIVE

This study aims to conduct an extensive analysis of autoimmune bullous diseases, particularly pemphigus vulgaris and bullous pemphigoid, in Shanghai, China, from 2016 to 2023. It seeks to understand the demographic profiles, comorbidities, mortality rates, risk factors, and socioeconomic impacts associated with autoimmune bullous disease.

METHODS

A cross-sectional study design was employed, enrolling 1,072 patients. Diagnostic measures included clinical manifestations, histopathology, direct immunofluorescence, and serologic tests. The study also involved a detailed socioeconomic analysis and evaluation of occupational risks.

RESULTS

The findings highlight a significant occupational risk in industries requiring enhanced safety measures, with a notable prevalence of autoimmune bullous disease among workers in these sectors. A considerable portion of the patients were from low-income backgrounds with limited literacy, indicating the economic burden of autoimmune bullous disease. A key discovery of the study is the potential pathological link between autoimmune bullous disease and interstitial lung disease.

CONCLUSION

This research, one of the first comprehensive studies on autoimmune bullous disease in China, underscores the need for targeted healthcare strategies and further investigation into autoimmune bullous disease, particularly its relationship with interstitial lung disease.

Comparison of serum cytokines and chemokines levels and clinical significance in patients with pemphigus vulgaris-A retrospective study

In this study, we aimed to examine the relationship between the serum cytokine levels of patients with pemphigus vulgaris (PV) and the Pemphigus Disease Area Index (PDAI), along with the presence of anti-desmoglein (Dsg) 1 antibody, anti-Dsg3 antibody and co-infection among patients with pemphigus vulgaris. This retrospective study included 62 PV patients and 59 healthy individuals who attended the Second Affiliated Hospital of Kunming Medical University from November 2014 to November 2022. The serum concentrations of cytokines and chemokines were assessed using the Luminex 200 System (a high-throughput cytokine detection method). Additionally, anti-Dsg1 and anti-Dsg3 antibodies were determined through enzyme-linked immunosorbent assay, while disease severity was evaluated using the PDAI scoring system. The PV group exhibited elevated levels of Th1 cytokines (such as interleukin (IL)-1RA, IL-1β, IL-2, IL-12p70, GM-CSF, TNF-α, IL-18, IFN-γ), Th2 cytokines (IL-5, IL-10, IL-13) and Th17/Th22-related cytokines (IL-17A, IL-22) compared to the healthy control group (p < 0.05). Conversely, the levels of chemokines (macrophage inflammatory protein-1 alpha (MIP-1α), stromal cell-derived factor-1 alpha (SDF-1α), interferon-inducible protein-10 (IP-10), Regulated on Activation in Normal T-Cell Expressed And Secreted (RANTES), growth-regulated on-gene-alpha (GRO-α), MIP-1β) and Th2 (IL-31) were lower in the PV group compared to the healthy control group (p < 0.05). No significant differences were observed in other cytokines and chemokines (p > 0.05). Additionally, IL-7, IFN-γ, IL-18 and GRO-α showed positive correlations with PDAI, IL-6 correlated positively with anti-Dsg3 antibody levels, and IL-12p70, IL-18, and IFN-γ correlated positively with anti-Dsg1 antibody levels. Furthermore, IL-15 exhibited a positive association with skin infections. PV patients have elevated levels of various cytokines and chemokines, and there are different degrees of elevation in cytokines and chemokines associated with the activation of various T cell subsets. PDAI and the Dsg1 antibody levels are mainly related to the Th1-related cytokines.

Scoring Criteria for Autoimmune Bullous Diseases: Utility, Merits, and Demerits

Background

Scoring systems play a crucial role in dermatology by providing objective measurements of disease severity, treatment efficacy, and outcome comparisons. In autoimmune blistering diseases (AIBDs), standardized scoring systems are essential for accurate evaluations; however, there is currently a lack of consensus on scoring methods.

Objective

This literature review explores scoring systems in AIBDs by tracing their development, addressing challenges, and highlighting their role in defining endpoints, regulatory considerations, and clinical trials.

Materials and Methods

Existing scoring systems for AIBDs, such as the Pemphigus Disease Area Index, Autoimmune Bullous Skin Disorder Intensity Score, Pemphigus Oral Lesions Intensity Score, Oral Disease Severity Score, and Pemphigus Vulgaris Activity Score, are examined for their validity, reliability, and responsiveness. The Bullous Pemphigoid Disease Area Index for bullous pemphigoid is also discussed. The concept of minimal clinically important differences is explored to determine clinically significant improvements in disease severity.

Conclusion

This review provides a comprehensive understanding of the central role of scoring systems in dermatology and their implications for research and clinical practice in AIBDs.

Efgartigimod as a novel FcRn inhibitor for autoimmune disease

Immunoglobulin G (IgG) autoantibodies can lead to the formation of autoimmune diseases through Fab and/or Fc-mediated interactions with host molecules as well as activated T cells. The neonatal Fc receptor (FcRn) binds at acidic pH IgG and albumin, and the mechanism for prolonging serum IgG half-life is making IgG re-entry into circulation by prompting it not to be degraded by lysosomes and back to the cell surface. Given the FcRn receptor's essential role in IgG homeostasis, one of the strategies to promote the quick degradation of endogenous IgG is to suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like myasthenia gravis (MG), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), stiff person syndrome, and immune thrombocytopenia (ITP). We elaborately read the literature about efgartigimod and systematically reviewed the research progress and clinical application of this novel FcRn inhibitor in autoimmune diseases. Efgartigimod is the firstly FcRn antagonist developed and was approved on 17 December 2021 by the United States for the therapy of acetylcholine receptor-positive MG. In January 2022, efgartigimod received its second regulatory approval in Japan. In addition, the market authorization application in Europe was submitted and validated in August 2021. China's National Medical Products Administration officially accepted the marketing application of efgartigimod on July 13, 2022. To suppress the function of FcRn, which is beneficial to the treatment of IgG-driven autoimmune disorders like MG, CIDP, ITP, and stiff person syndrome. We review the rationale, clinical evidence, and future perspectives of efgartigimod for the treatment of autoimmune disease.

High throughput screening identifies repurposable drugs for modulation of innate and acquired immune responses

A balanced immune system is essential to maintain adequate host defense and effective self-tolerance. While an immune system that fails to generate appropriate response will permit infections to develop, uncontrolled activation may lead to autoinflammatory or autoimmune diseases. To identify drug candidates capable of modulating immune cell functions, we screened 1200 small molecules from the Prestwick Chemical Library for their property to inhibit innate or adaptive immune responses. Our studies focused specifically on drug interactions with T cells, B cells, and polymorphonuclear leukocytes (PMNs). Candidate drugs that were validated in vitro were examined in preclinical models to determine their immunomodulatory impact in chronic inflammatory diseases, here investigated in chronic inflammatory skin diseases. Using this approach, we identified several candidate drugs that were highly effective in preclinical models of chronic inflammatory disease. For example, we found that administration of pyrvinium pamoate, an FDA-approved over-the-counter anthelmintic drug, suppressed B cell activation in vitro and halted the progression of B cell-dependent experimental pemphigoid by reducing numbers of autoantigen-specific B cell responses. In addition, in studies performed in gene-deleted mouse strains provided additional insight into the mechanisms underlying these effects, for example, the receptor-dependent actions of tamoxifen that inhibit immune-complex-mediated activation of PMNs. Collectively, our methods and findings provide a vast resource that can be used to identify drugs that may be repurposed and used to promote or inhibit cellular immune responses.

Factors associated with non-pathogenic antibodies against desmoglein-3 in pemphigus foliaceus

BACKGROUND

Anti-desmoglein (Dsg)1 is produced in pemphigus foliaceus (PF), affecting exclusively the skin. Pemphigus vulgaris (PV) shows the production of anti-Dsg3 in the mucosal form, and anti-Dsg1 and 3 in the mucocutaneous form. Anti-Dsg3 autoantibodies have been rarely reported in PF.

OBJECTIVES

To determine the factors associated with the production and pathogenicity of anti-Dsg3 in PF.

METHODS

Comparative analytical study of three patients groups: 16 PF-anti-Dsg3+, and 42 PF-anti-Dsg3(-) and 22 PV treatment-naïve cases. Serum was used in the anti-Dsg1 and 3 ELISA, and in immunoblotting (IB) with human epidermis extract. The expression of Dsg1 and 3 in paraffin sections was analyzed by immunohistochemistry (IHC). HLA-DRB1 alleles were compiled from a database.

RESULTS

In the PF-anti-Dsg3+ group: age range similar to that of the PV group (p > 0.9999); predominance of the generalized form of PF (p = 0.002); anti-Dsg3 titers lower than those of PV (p < 0.0001); IB confirmed Dsg3 identification in one (8.33%) of 12 patients; IHC showed exclusive cytoplasmic internalization of Dsg1; HLA-DRB1 alleles of susceptibility to PF, with the absence of alleles associated with PV, in the five typed patients.

STUDY LIMITATIONS

Most of the patients in the PF-anti-Dsg3+ group were undergoing treatment.

CONCLUSION

The presence of anti-Dsg3 antibodies in PF was related to older age (comparable to that of PV) and the generalized form of PF. The non-pathogenicity of anti-Dsg3 antibodies in PF can be attributed to the low serum anti-Dsg3 titers, the lack of Dsg3 internalization as detected by IHC, and the absence of PV-associated HLA-DRB1 alleles.

The triangular crusty nose: a clinical clue for pemphigus in the context of mask wearing

Since the onset of the COVID-19 pandemic, there has been a widespread adoption of mask wearing. With prolonged use of facial masks, an increasing number of new-onset inflammatory facial dermatoses have been observed, along with flaring of pre-existing dermatoses. Common dermatoses triggered by facial mask wearing include contact dermatitis, maskne (a subtype of mechanical acne) and mask-induced rosacea. In this report, we present two cases of pemphigus vulgaris, presenting first with a well-defined triangular crusty nose induced by mask wearing during the COVID pandemic.

Targeting Bruton's tyrosine kinase (BTK) as a signaling pathway in immune-mediated diseases: from molecular mechanisms to leading treatments

Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase, plays a remarkable role in the transmission and amplification of extracellular signals to intracellular signaling pathways. Various types of cells use the BTK pathway to communicate, including hematopoietic cells particularly B cells and T cells. The BTK pathway plays a role in controlling the proliferation, survival, and functions of B cells as well as other myeloid cells. First, second, and third-generation BTK inhibitors are currently being evaluated for the treatment of immune-mediated diseases in addition to B cell malignancies. In this article, the available evidence on the action mechanisms of BTK inhibitors is reviewed. Then, the most recent data obtained from preclinical studies and ongoing clinical trials for the treatment of autoimmune diseases, such as pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, systemic lupus erythematosus, Sjögren's disease, rheumatoid arthritis, systemic sclerosis, multiple sclerosis, myasthenia gravis, and inflammatory diseases such as psoriasis, chronic spontaneous urticaria, atopic dermatitis, and asthma are discussed. In addition, adverse effects and complications associated with BTK inhibitors as well as factors predisposing patients to BTK inhibitors complications are discussed.

shRNA-Targeting Caspase-3 Inhibits Cell Detachment Induced by Pemphigus Vulgaris Autoantibodies in HaCaT Cells

Pemphigus is an autoimmune disease that affects the skin and mucous membranes, induced by the deposition of pemphigus IgG, which mainly targets desmogleins 1 and 3 (Dsg1 and 3). This autoantibody causes steric interference between Dsg1 and 3 and the loss of cell adhesion, producing acantholysis. This molecule and its cellular effects are clinically reflected as intraepidermal blistering. Pemphigus vulgaris-IgG (PV-IgG) binding involves p38MAPK-signaling-dependent caspase-3 activation. The present work assessed the in vitro effect of PV-IgG on the adherence of HaCaT cells dependent on caspase-3. PV-IgG induced cell detachment and apoptotic changes, as demonstrated by annexin fluorescent assays. The effect of caspase-3 induced by PV-IgG was suppressed in cells pre-treated with caspase-3-shRNA, and normal IgG (N-IgG) as a control had no relevant effects on the aforementioned parameters. The results demonstrated that shRNA reduces caspase-3 expression, as measured via qRT-PCR and via Western blot and immunofluorescence, and increases cell adhesion. In conclusion, shRNA prevented in vitro cell detachment and the late effects of apoptosis induced by PV-IgG on HaCaT cells, furthering our understanding of the molecular role of caspase-3 cell adhesion dependence in pemphigus disease.

[Paraneoplastic pemphigus with underlying Castleman's disease in a 16-year-old girl]

Paraneoplastic pemphigus is a rare, life-threatening autoimmune disease that is clinically characterized by mostly extensive and refractory mucosal erosions and polymorphous skin lesions. We report here on a 16-year-old girl with isolated oral erosions, in whom mucosal pemphigoid was initially suspected and after treatment with prednisolone and dapsone marked improvement was achieved. However, a few months later the patient developed massive respiratory insufficiency as a result of bronchiolitis obliterans, so that a lung transplant was planned. As part of the preparatory diagnostic workup, unicentric, abdominally localized Castleman's disease was diagnosed, which ultimately led to the diagnosis of paraneoplastic pemphigus as evidenced by envoplakin autoantibodies. Tumor resection and subsequent lung transplantation achieved good results with sustained mucocutaneous remission.

A Comprehensive Review on the Intricate Interplay between COVID-19 Immunization and the New Onset of Pemphigus Foliaceus

Autoimmune bullous diseases (AIBDs) are characterized by the formation of vesicles, bullous lesions, and mucosal erosions. The autoantibodies target the cellular anchoring structures from the surface of epidermal keratinocyte named desmosomes, leading to a loss of cellular cohesion named acantholysis. AIBDs are classified into intraepidermal or subepidermal types based on clinical features, histological characteristics, and immunofluorescence patterns. Pemphigus foliaceus (PF) is an acquired, rare, autoimmune skin condition associated with autoantibodies that specifically target desmoglein-1, leading to a clinical presentation characterized by delicate cutaneous blisters, typically sparing the mucous membranes. Several factors, including genetic predisposition, environmental triggers, malignancies, medication use, and vaccination (for influenza, hepatitis B, rabies, tetanus, and more recently, severe acute respiratory syndrome Coronavirus 2 known as SARS-CoV-2), can potentially trigger the onset of pemphigus. With the advent of vaccines playing a pivotal role in combatting the 2019 coronavirus disease (COVID-19), extensive research has been conducted globally to ascertain their efficacy and potential cutaneous adverse effects. While reports of AIBDs post-COVID-19 vaccination exist in the medical literature, instances of PF following vaccination have been less commonly reported worldwide. The disease's pathophysiology is likely attributed to the resemblance between the ribonucleic acid (RNA) antigen present in these vaccines and cellular nuclear matter. The protein produced by the BNT-162b2 messenger ribonucleic acid (mRNA) vaccine includes immunogenic epitopes that could potentially trigger autoimmune phenomena in predisposed individuals through several mechanisms, including molecular mimicry, the activation of pattern recognition receptors, the polyclonal stimulation of B cells, type I interferon production, and autoinflammation. In this review, we present a comprehensive examination of the existing literature regarding the relationship between COVID-19 and PF, delving into their intricate interactions. This exploration improves the understanding of both pemphigus and mRNA vaccine mechanisms, highlighting the importance of close monitoring for PF post-immunization.

Gut Microbiome Dysbiosis in Patients with Pemphigus and Correlation with Pathogenic Autoantibodies

BACKGROUND

Pemphigus is a group of potentially life-threatening autoimmune bullous diseases induced by pathogenic autoantibodies binding to the surface of epidermal cells. The role of the gut microbiota (GM) has been described in various autoimmune diseases. However, the impact of the GM on pemphigus is less understood. This study aimed to investigate whether there was alterations in the composition and function of the GM in pemphigus patients compared to healthy controls (HCs).

METHODS

Fecal samples were collected from 20 patients with active pemphigus (AP), 11 patients with remission pemphigus (PR), and 47 HCs. To sequence the fecal samples, 16S rRNA was applied, and bioinformatic analyses were performed.

RESULTS

We found differences in the abundance of certain bacterial taxa among the three groups. At the family level, the abundance of Prevotellaceae and Coriobacteriaceae positively correlated with pathogenic autoantibodies. At the genus level, the abundance of Klebsiella, Akkermansia, Bifidobacterium, Collinsella, Gemmiger, and Prevotella positively correlated with pathogenic autoantibodies. Meanwhile, the abundance of Veillonella and Clostridium_XlVa negatively correlated with pathogenic autoantibodies. A BugBase analysis revealed that the sum of potentially pathogenic bacteria was elevated in the AP group in comparison to the PR group. Additionally, the proportion of Gram-negative bacteria in the PR group was statistically significantly lower in comparison to the HC group.

CONCLUSION

The differences in GM composition among the three groups, and the correlation between certain bacterial taxa and pathogenic autoantibodies of pemphigus, support a linkage between the GM and pemphigus.

Beyond the skin: B cells in pemphigus vulgaris, tolerance and treatment

Pemphigus vulgaris (PV) is a rare autoimmune bullous disease characterized by blistering of the skin and mucosa owing to the presence of autoantibodies against the desmosome proteins desmoglein 3 and occasionally in conjunction with desmoglein 1. Fundamental research into the pathogenesis of PV has revolutionized its treatment and outcome with rituximab, a B-cell-depleting therapy. The critical contribution of B cells to the pathogenesis of pemphigus is well accepted. However, the exact pathomechanism, mechanisms of onset, disease course and relapse remain unclear. In this narrative review, we provide an overview of the fundamental research progress that has unfolded over the past few centuries to give rise to current and emerging therapies. Furthermore, we summarize the multifaceted roles of B cells in PV, including their development, maturation and antibody activity. Finally, we explored how these various aspects of B-cell function contribute to disease pathogenesis and pave the way for innovative therapeutic interventions.

Immunostimulatory effects of Toll-like receptor ligands as adjuvants in establishing a novel mouse model for pemphigus vulgaris

BACKGROUND

The meticulous selection of appropriate vaccine adjuvants is crucial for optimizing immune responses. Traditionally, pemphigus vulgaris (PV), an autoimmune disorder, has been modelled using complete Freund's adjuvant (CFA). In this study, we aimed to discern potential variations in immune responses elicited by Toll-like receptor (TLR) ligands as compared to CFA.

METHODS

A comprehensive investigation was conducted, comparing the effects of these adjuvants in conjunction with ovalbumin or desmoglein-3. Flow cytometry was employed to analyse distinct cell subsets, while enzyme-linked immunosorbent assay quantified antigen-specific antibodies and cytokine levels. Histological examination of harvested skin tissues and transcriptome analysis of skin lesions were performed to identify differentially expressed genes.

RESULTS

TLR ligands demonstrated efficacy in inducing PV-like symptoms in wild-type mice, in contrast to CFA. This underscored the substantial impact of the adjuvant on self-antigen tolerance. Furthermore, we proposed an enhanced method for establishing a PV model through adoptive transfer, substituting CFA with TLR ligands. Our results revealed that in contrast to the perception that CFA being the most potent immunopotentiator reported, CFA promoted regulatory T cells (Treg), follicular regulatory T cells and IL-10-producing neutrophils, whereas TLR ligands downregulated CCL17 and IL-10. This suggested potential implications for the recruitment and activation of Treg subsets. While B cell and CD8+ T cell responses exhibited similarity, CFA induced less activation in dendritic cell subsets. A novel mouse model of PV and systemic comparison of immunostimulatory effects of adjuvants were provided by this study.

CONCLUSIONS

The systematic comparison of CFA and TLR ligands shed light on the distinctive properties of these adjuvants, presenting innovative mouse models for the investigation of pemphigus. This study significantly contributes to adjuvant research and advances our understanding of PV pathogenesis.

KEY POINTS/HIGHLIGHTS

Immunization with desmoglein 3 and Toll-like receptor (TLR) ligands effectively induces pemphigus symptoms in wild-type mice, whereas complete Freund's adjuvant (CFA) fails. TLR ligands heightened the autoreactivity of donor cells in the adoptive transfer pemphigus model. CFA promoted regulatory T cells and IL-10-producing neutrophils, whereas TLR ligands downregulated CCL17 and IL-10, leading to more effective immune responses.

Immune interplay from circulation to local lesion in pemphigus pathogenesis

Pemphigus, a potentially lethal autoimmune skin disease, is mediated by desmoglein-specific antibodies, manifesting cutaneous and mucosal blisters and erosions. The interaction between multiple immune counterparts contributes to the progress of pemphigus. Currently, the emergence of bioinformatic analysis enables investigators to gain a global picture of the pemphigus immune network, based on the exhaustive pedigree annotation of multiple subsets. T helper subsets dominate the landscape as mentioned previously, and innate immune cells have been involved as well. Of particular interests is which phenotype of T cells orchestrates the autoimmune process and chronic inflammation in a certain condition. In this review, the circulatory and peripheral immune cells and cytokine components constituting the immune microenvironment are separately discussed to provide a perspective on pemphigus pathogenesis, with particular reference to insights provided by the bioinformation technique.

Re-evaluating the prevalence of anti-desmocollin-1 IgA autoantibodies in canine pemphigus foliaceus

Pemphigus foliaceus (PF) is an autoimmune skin disease of dogs characterized by intraepidermal pustules containing neutrophils and dissociated keratinocytes that develop in association with circulating and tissue-bound IgG autoantibodies. A subset of IgG autoantibodies in canine PF target desmocollin-1 (DSC1), a component of intercellular adhesion complexes within the epidermis. Passive transfer of IgG autoantibodies from canine PF sera to mice was previously shown to induce skin disease in the absence of infiltrating neutrophils. In attempts to identify a mechanism responsible for neutrophil recruitment, past studies evaluated the prevalence of IgA autoantibodies in canine PF sera where they were found in <20% of affected dogs. We re-evaluated the prevalence of anti-DSC1 IgA in canine PF due to concerns regarding the sensitivity of previously used methods. We hypothesized that anti-DSC1 IgA are present in most dogs with PF but have been under-detected due to competition with concurrent anti-DSC1 IgG for binding to their mutual antigenic target. Despite removing approximately 80% of IgG from patient sera using affinity chromatography, we did not detect an increase in anti-DSC1 IgA by performing indirect immunofluorescence on canine DSC1-transfected HEK293T cells. Taken together, our results do not support a role for pathogenic IgA in canine PF.

Immunologic Profiling of Immune-Related Cutaneous Adverse Events with Checkpoint Inhibitors Reveals Polarized Actionable Pathways

PURPOSE

Immune-related cutaneous adverse events (ircAE) occur in ≥50% of patients treated with checkpoint inhibitors, but the underlying mechanisms for ircAEs are poorly understood.

EXPERIMENTAL DESIGN

Phenotyping/biomarker analyses were conducted in 200 patients on checkpoint inhibitors [139 with ircAEs and 61 without (control group)] to characterize their clinical presentation and immunologic endotypes. Cytokines were evaluated in skin biopsies, skin tape strip extracts, and plasma using real-time PCR and Meso Scale Discovery multiplex cytokine assays.

RESULTS

Eight ircAE phenotypes were identified: pruritus (26%), maculopapular rash (MPR; 21%), eczema (19%), lichenoid (11%), urticaria (8%), psoriasiform (6%), vitiligo (5%), and bullous dermatitis (4%). All phenotypes showed skin lymphocyte and eosinophil infiltrates. Skin biopsy PCR revealed the highest increase in IFNγ mRNA in patients with lichenoid (P < 0.0001) and psoriasiform dermatitis (P < 0.01) as compared with patients without ircAEs, whereas the highest IL13 mRNA levels were detected in patients with eczema (P < 0.0001, compared with control). IL17A mRNA was selectively increased in psoriasiform (P < 0.001), lichenoid (P < 0.0001), bullous dermatitis (P < 0.05), and MPR (P < 0.001) compared with control. Distinct cytokine profiles were confirmed in skin tape strip and plasma. Analysis determined increased skin/plasma IL4 cytokine in pruritus, skin IL13 in eczema, plasma IL5 and IL31 in eczema and urticaria, and mixed-cytokine pathways in MPR. Broad inhibition via corticosteroids or type 2 cytokine-targeted inhibition resulted in clinical benefit in these ircAEs. In contrast, significant skin upregulation of type 1/type 17 pathways was found in psoriasiform, lichenoid, bullous dermatitis, and type 1 activation in vitiligo.

CONCLUSIONS

Distinct immunologic ircAE endotypes suggest actionable targets for precision medicine-based interventions.

Ofatumumab subcutaneous injection successfully treated patients with pemphigus vulgaris relapse post rituximab

The therapeutic strategy for the treatment of pemphigus vulgaris (PV) still needs optimization because of the multiple deficiencies of glucocorticoid and rituximab. Ofatumumab, another CD20 monoclonal antibody administrated subcutaneously, provides a possible alternative option. In this study, three patients experienced PV relapse after clinical remission induced by rituximab. With written informed consent, they received an ofatumumab (20 mg) subcutaneous injection twice (2 weeks apart) in combination with a prednisone dose adjusted according to their weight and disease severity. Over the 24-week observation, two of three patients achieved lesion clear-up under prednisone (0.2 mg/kg per day), and the other patient's pemphigus disease area index dropped from 39 to 3 with prednisone (15 mg/day). The anti-desmoglein antibody levels and CD19+B cell counts declined compared to those at baseline. No severe adverse events were observed within the 24-week follow-up. In summary, we propose a protocol of ofatumumab for patients with refractory PV and report positive treatment outcomes of three patients who received this regimen.

Pulmonary interstitial lesions in pemphigus mouse model: Verifying pemphigus may not be only limited to skin and mucosa

Interstitial lung disease (ILD) has been identified as a prevalent complication and significant contributor to mortality in individuals with pemphigus. In this study, a murine model of pemphigus was developed through the subcutaneous administration of serum IgG obtained from pemphigus patients, allowing for an investigation into the association between pemphigus and ILD. Pulmonary interstitial lesions were identified in the lungs of a pemphigus mouse model through histopathology, RT-qPCR and Sircol assay analyses. The severity of these lesions was found to be positively associated with the concentration of IgG in the injected serum. Additionally, DIF staining revealed the deposition of serum IgG in the lung tissue of pemphigus mice, indicating that the subcutaneous administration of human IgG directly impacted the lung tissue of the mice, resulting in damage. This study confirms the presence of pulmonary interstitial lesions in the pemphigus mouse model and establishes a link between pemphigus and ILD.

Serum interleukin-6 concentration in patients with pemphigus

Pemphigus is a rare blistering autoimmune disease that damages the integumentary system and lowers the quality of life of patients. Interleukin-6 (IL-6) has been linked to the immunopathogenesis of pemphigus, according to recent research. Thus, the investigation purpose was to assess the function of IL-6 in the development and intensity of pemphigus disease. Between January 2022 and August 2022, a case-series study involving 26 patients with pemphigus vulgaris (PV), four patients with pemphigus foliaceus (PF), and 20 healthy volunteers was carried out at the Ho Chi Minh City Hospital of Dermato-Venereology. Patients with PV and PF had significantly higher serum IL-6 concentrations than healthy volunteers (p<0.001). Patients with a positive Nikolsky sign had significantly higher serum IL-6 concentrations than those with a negative sign (p<0.001). The serum IL-6 concentration and the pemphigus disease area index were found to significantly correlate (r=0.8, p<0.001). According to our findings, IL-6 might be a significant factor in pemphigus development and severity. Thus, novel treatments that specifically target IL-6 could be a good option for managing pemphigus, particularly in its more severe forms.

State-of-the-art diagnosis of autoimmune blistering diseases

Autoimmune blistering disorders (AIBDs) are a heterogeneous group of approximately a dozen entities comprising pemphigus and pemphigoid disorders and dermatitis herpetiformis. The exact diagnosis of AIBDs is critical for both prognosis and treatment and is based on the clinical appearance combined with the detection of tissue-bound and circulating autoantibodies. While blisters and erosions on the skin and/or inspectable mucosal surfaces are typical, lesions may be highly variable with erythematous, urticarial, prurigo-like, or eczematous manifestations. While direct immunofluorescence microscopy (IFM) of a perilesional biopsy is still the diagnostic gold standard, the molecular identification of the major target antigens opened novel therapeutic avenues. At present, most AIBDs can be diagnosed by the detection of autoantigen-specific serum antibodies by enzyme-linked immunosorbent assay (ELISA) or indirect IFM when the clinical picture is known. This is achieved by easily available and highly specific and sensitive assays employing recombinant immunodominant fragments of the major target antigens, i.e., desmoglein 1 (for pemphigus foliaceus), desmoglein 3 (for pemphigus vulgaris), envoplakin (for paraneoplastic pemphigus), BP180/type XVII collagen (for bullous pemphigoid, pemphigoid gestationis, and mucous membrane pemphigoid), laminin 332 (for mucous membrane pemphigoid), laminin β4 (for anti-p200 pemphigoid), type VII collagen (for epidermolysis bullosa acquisita and mucous membrane pemphigoid), and transglutaminase 3 (for dermatitis herpetiformis). Indirect IFM on tissue substrates and in-house ELISA and immunoblot tests are required to detect autoantibodies in some AIBD patients including those with linear IgA disease. Here, a straightforward modern approach to diagnosing AIBDs is presented including diagnostic criteria according to national and international guidelines supplemented by long-term in-house expertise.

Maintenance treatment of pemphigus with rituximab in real life: A single-center study of 50 patients

BACKGROUND

Following the RITUX 3 therapeutic trial, the French national diagnosis and care protocol (NDCP) for the treatment of pemphigus was updated in 2018. The updated protocol recommends initial treatment with rituximab (RTX) followed by maintenance therapy at 12 and 18 months, and potentially at 6 months where there are risk factors for early relapse. We evaluated these recommendations regarding the management of our own patients.

PATIENTS AND METHODS

Our single-center retrospective study included all patients with pemphigus diagnosed between 01/2015 and 10/2020 and receiving at least one initial infusion of RTX. We collected the following data: type of pemphigus, severity, levels of anti-desmoglein 1 and 3 antibodies at diagnosis and between 2 and 6 months after initial RTX, presence or absence of maintenance therapy and modalities, time to first relapse and duration of associated systemic corticosteroid therapy ≥5 mg/day. Maintenance treatment modalities were as follows: no maintenance treatment, maintenance "on demand" (MT1) i.e. not performed at the rate imposed by the NDCP, and maintenance "according to NDCP" (MT2).

RESULTS

Fifty patients were included (women 54%, median age 58 years, pemphigus vulgaris 68%, moderate to severe 68%). Initial RTX was combined with systemic corticosteroid therapy at 0.5 to 1 mg/kg in 74% of cases. Twenty-seven patients (54%) received no maintenance therapy, 13 were on an MT1 regimen (26%), and 10 were on an MT2 regimen (20%). Median follow-up was 42 months. At the last follow-up, 39 patients (78%) were in complete remission. A total of 25 patients (50%) relapsed: 18/27 (67%) patients without maintenance, 5/13 (38%) with MT1, and 2/10 (20%) with MT2 (p = 0.026). The probability of relapse over time was significantly lower in patients receiving maintenance therapy compared to those who receiving none (p = 0.022). The median time to relapse was 15 months in patients without maintenance, and 30 and 28 in those with maintenance (p = 0.27). The median duration of systemic corticosteroid therapy ≥ 5 mg/day in the no-maintenance group was 10 months, compared to 7 and 9 months respectively in MT1 and MT2 (p = 0.91).

CONCLUSION

Our study confirms the value of RTX maintenance therapy in pemphigus in real life.

A Case of an Autoimmune Blistering Disease: Pemphigus Vulgaris

Pemphigus vulgaris is a rare autoimmune disorder characterized by the formation of intraepithelial blisters that clinically appear as erosions and flaccid bullae on the skin and mucus membranes. Herein, we report a case of pemphigus vulgaris in an elderly male. He was initially misdiagnosed by his primary care provider and given topical lidocaine and acetaminophen with hydrocodone, without improvement in symptoms. This delay in treatment caused a worsening of his condition. The patient presented to our dermatology office two months after his primary care visit and reported worsening blisters and pain. Clinically he presented with flaccid bullae, crusted erosions, and erythematous plaques on the chest, back, abdomen, arms, and legs, and a tender oral ulcer. Two punch biopsies were obtained and sent for direct immunofluorescence and routine histology. The biopsy results confirmed the diagnosis of pemphigus vulgaris. Our patient achieved clearance after four weeks of oral prednisone and maintained clearance after a slow prednisone taper and the addition of mycophenolate mofetil 1g twice daily. We aim to bring awareness of the clinical presentation and treatment regimen of pemphigus vulgaris to prevent misdiagnosis and delayed care.

Treatment with immunosuppressants did not increase the risk of COVID-19 in pemphigus patients: A single-center survey-based study

BACKGROUND

The prevalence and outcomes of coronavirus 2019 (COVID-19) among patients using glucocorticoids and immunosuppressants remain controversial.

AIM

The study aims to investigate the impact of immunosuppressants especially glucocorticoids on patients in the Autoimmune Bullous Diseases Cohort of West China Hospital (AIBDWCH) during COVID-19.

METHODS

We conducted a cross-sectional survey from December 7, 2022, to February 8, 2023, using questionnaires administered either face-to-face or by phone. COVID-19 cases were classified as confirmed, probable, or suspected according to World Health Organization criteria. Patients were divided into Group A (confirmed and probable cases) and Group B (suspected and other cases). The impact of glucocorticoids and immunosuppressive agents on COVID-19 disease and progression was evaluated with logistic regression models.

RESULTS

This study included 111 patients with pemphigus. Overweight patients had a reduced risk of confirmed COVID-19 (odds ratio [OR] 0.35 [95 % CI 0.13-0.97], p = 0.045). Patients treated with a medium dose of prednisone during the pandemic had a lower incidence of COVID-19 compared to those on low doses, though the difference was not statistically significant. No independent effects of age, sex, comorbidities, and therapies were observed. No significant differences were found in COVID-19 symptoms among different therapy groups.

CONCLUSIONS

Treatment with immunosuppressants, particularly glucocorticoids at low-to-medium doses, did not elevate COVID-19 risk in pemphigus patients. Consistent outcomes across treatments confirm the safety of these therapies during the pandemic.

Epidemiology of malignant tumors in patients with pemphigus: an analysis of trends from 1955 to 2021

BACKGROUND

The incidence of malignant tumors has increased in patients with non-paraneoplastic pemphigus, although there has been no systematic analysis of global epidemiology.

OBJECTIVE

To explore the epidemiology of various types of non-paraneoplastic pemphigus associated with malignant tumors.

METHODS

Five databases from establishment through October 20, 2023, were searched. STATA SE 17 was used for the data analysis. Subgroup, meta-regression, and sensitivity analyses were used to evaluate the heterogeneity of pooled studies.

RESULTS

A total of 6679 participants were included in our meta-analysis from 16 studies. The aggregated prevalence of tumors in patients diagnosed with pemphigus was 8%. The prevalence was 7% in patients with pemphigus vulgaris, 10% in those with pemphigus foliaceus, and 12% in individuals diagnosed with other types of pemphigus. The prevalence was 8% in Asia, 11% in Europe, and 8% in North America. From a country-specific perspective, patients with pemphigus from Israel, Greece, and Germany exhibited a higher prevalence of tumors at 11%. Furthermore, when categorized by the duration of the study period, the highest prevalence was observed in studies spanning 10 to 20 years, at 11%.

CONCLUSION

These findings demonstrate the incidence and prevalence of malignant tumors in patients with non-paraneoplastic pemphigus, which may achieve early detection and intervention, and then reduce mortality rates.

Desmosomal Hyper-adhesion Affects Direct Inhibition of Desmoglein Interactions in Pemphigus

During differentiation, keratinocytes acquire a strong, hyper-adhesive state, where desmosomal cadherins interact calcium ion independently. Previous data indicate that hyper-adhesion protects keratinocytes from pemphigus vulgaris autoantibody-induced loss of intercellular adhesion, although the underlying mechanism remains to be elucidated. Thus, in this study, we investigated the effect of hyper-adhesion on pemphigus vulgaris autoantibody-induced direct inhibition of desmoglein (DSG) 3 interactions by atomic force microscopy. Hyper-adhesion abolished loss of intercellular adhesion and corresponding morphological changes of all pathogenic antibodies used. Pemphigus autoantibodies putatively targeting several parts of the DSG3 extracellular domain and 2G4, targeting a membrane-proximal domain of DSG3, induced direct inhibition of DSG3 interactions only in non-hyper-adhesive keratinocytes. In contrast, AK23, targeting the N-terminal extracellular domain 1 of DSG3, caused direct inhibition under both adhesive states. However, antibody binding to desmosomal cadherins was not different between the distinct pathogenic antibodies used and was not changed during acquisition of hyper-adhesion. In addition, heterophilic DSC3-DSG3 and DSG2-DSG3 interactions did not cause reduced susceptibility to direct inhibition under hyper-adhesive condition in wild-type keratinocytes. Taken together, the data suggest that hyper-adhesion reduces susceptibility to autoantibody-induced direct inhibition in dependency on autoantibody-targeted extracellular domain but also demonstrate that further mechanisms are required for the protective effect of desmosomal hyper-adhesion in pemphigus vulgaris.

Exploring the depths of IgG4: insights into autoimmunity and novel treatments

IgG4 subclass antibodies represent the rarest subclass of IgG antibodies, comprising only 3-5% of antibodies circulating in the bloodstream. These antibodies possess unique structural features, notably their ability to undergo a process known as fragment-antigen binding (Fab)-arm exchange, wherein they exchange half-molecules with other IgG4 antibodies. Functionally, IgG4 antibodies primarily block and exert immunomodulatory effects, particularly in the context of IgE isotype-mediated hypersensitivity reactions. In the context of disease, IgG4 antibodies are prominently observed in various autoimmune diseases combined under the term IgG4 autoimmune diseases (IgG4-AID). These diseases include myasthenia gravis (MG) with autoantibodies against muscle-specific tyrosine kinase (MuSK), nodo-paranodopathies with autoantibodies against paranodal and nodal proteins, pemphigus vulgaris and foliaceus with antibodies against desmoglein and encephalitis with antibodies against LGI1/CASPR2. Additionally, IgG4 antibodies are a prominent feature in the rare entity of IgG4 related disease (IgG4-RD). Intriguingly, both IgG4-AID and IgG4-RD demonstrate a remarkable responsiveness to anti-CD20-mediated B cell depletion therapy (BCDT), suggesting shared underlying immunopathologies. This review aims to provide a comprehensive exploration of B cells, antibody subclasses, and their general properties before examining the distinctive characteristics of IgG4 subclass antibodies in the context of health, IgG4-AID and IgG4-RD. Furthermore, we will examine potential therapeutic strategies for these conditions, with a special focus on leveraging insights gained from anti-CD20-mediated BCDT. Through this analysis, we aim to enhance our understanding of the pathogenesis of IgG4-mediated diseases and identify promising possibilities for targeted therapeutic intervention.