Rituximab and Corticosteroid Effect on Desmoglein-Specific B Cells and Desmoglein-Specific T Follicular Helper Cells in Pemphigus

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.

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.

Lichen planus pemphigoides with predominant mucous membrane involvement: a series of 12 patients and a literature review

Background

Lichen planus pemphigoides (LPP), an association between lichen planus and bullous pemphigoid lesions, is a rare subepithelial autoimmune bullous disease. Mucous membrane involvement has been reported previously; however, it has never been specifically studied.

Methods

We report on 12 cases of LPP with predominant or exclusive mucous membrane involvement. The diagnosis of LPP was based on the presence of lichenoid infiltrates in histology and immune deposits in the basement membrane zone in direct immunofluorescence and/or immunoelectron microscopy. Our systematic review of the literature, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, highlights the clinical and immunological characteristics of LPP, with or without mucous membrane involvement.

Results

Corticosteroids are the most frequently used treatment, with better outcomes in LPP with skin involvement alone than in that with mucous membrane involvement. Our results suggest that immunomodulators represent an alternative first-line treatment for patients with predominant mucous membrane involvement.

Sustained Remission Without Corticosteroids Among Patients With Pemphigus Who Had Rituximab as First-Line Therapy: Follow-Up of the Ritux 3 Trial

Importance

The Ritux 3 trial demonstrated the short-term efficacy and safety of first-line treatment with rituximab compared with a standard corticosteroid regimen in pemphigus. No data on the long-term follow-up of patients who received rituximab as first line are available.

Objective

To assess the long-term efficacy and safety of the Ritux 3 treatment regimen.

Design, Setting, and Participants

This 7-year follow-up study of the Ritux 3 trial included patients with pemphigus from 25 dermatology departments in France from January 1, 2010, to December 31, 2015.

Exposure

Patients were initially randomized in the rituximab plus prednisone group or prednisone-alone group.

Main outcomes and measures

The primary outcome was the 5- and 7-year disease-free survival (DFS) without corticosteroids, assessed by Kaplan-Meier curves. Secondary outcomes were occurrence of relapse, occurrence of severe adverse events (SAEs), and evolution of antidesmoglein (Dsg) antibody enzyme-linked immunosorbent assay values to predict long-term relapse.

Results

Of the 90 patients in the Ritux 3 trial, 83 were evaluated at the end of follow-up study visit (44 in the rituximab plus prednisone group; 39 in the prednisone-alone group) with a median (IQR) follow-up of 87.3 (79.1-97.5) months. Forty-three patients (93%) from the rituximab plus prednisone and 17 patients (39%) from the prednisone-alone group had achieved complete remission without corticosteroids at any time during the follow-up. Patients from the rituximab group had much longer 5- and 7-year DFS without corticosteroids than patients from the prednisone-alone group (76.7% and 72.1% vs 35.3% and 35.3%, respectively; P < .001), and had about half the relapses (42.2% vs 83.7%; P < .001). Patients who received rituximab as second-line treatment had shorter DFS than patients treated as first line (P = .007). Fewer SAEs were reported in the rituximab plus prednisone group compared with the prednisone-alone group, 31 vs 58 respectively, corresponding to 0.67 and 1.32 SAEs per patient, respectively (P = .003). The combination of anti-Dsg1 values of 20 or more IU/mL and/or anti-Dsg3 values of 48 or more IU/mL yielded 0.83 positive predictive value and 0.94 negative predictive value to predict long-term relapse.

Conclusions and Relevance

In this secondary analysis of the Ritux 3 trail, first-line treatment of patients with pemphigus with the Ritux 3 regimen was associated with long-term sustained complete remission without corticosteroid therapy without any additional maintenance infusion of rituximab.

Rituximab in the Management of Autoimmune Bullous Diseases: A Treatment-Resistant Case Series from a Single Central European Referral Center

Background and Objectives: Rituximab (RTX) has been the predominant treatment for autoimmune bullous diseases (AIBDs). The objective of this research was to assess the advantages and safety characteristics of RTX treatment in individuals with AIBD. This assessment focused on clinical remission and a reduction in glucocorticosteroid usage, its effect on the titers of autoantibodies targeting desmoglein-1 (DSG-1) and desmoglein-3 (DSG-3), and adverse occurrences during a 12-month follow-up period in a dermatology department within a Central European university context. Materials and Methods: Our case series involved eleven patients, including eight patients with pemphigus vulgaris, two with pemphigus foliaceus, and one with epidermolysis bullosa acquisita. They received a 1 g dose of rituximab, repeated over a two-week interval. Results: The reduction in a prednisone-equivalent dosage after 2, 6, and 12 months following the second RTX infusion was 65.05%, 73.99%, and 76.93%, in that order. The titers of antibodies against DSG-1 exhibited reductions of 43.29%, 75.86%, and 54.02% at 2, 6, and 12 months, respectively. By contrast, the antibody concentrations targeting DSG-3 displayed a decrease of 27.88%, 14.48%, and 5.09% at the corresponding time points. Over the course of the 12-month monitoring period, 18.18% of patients experienced disease relapse, while the remaining individuals achieved either complete or partial remission with minimal or no therapy. Adverse effects were noted in 36.36% of the patient population; they were mild, and no serious adverse effects were reported. Conclusions: RTX represents an efficacious and well-tolerated therapeutic option for the management of AIBD and merits consideration in cases of refractory AIBD. However, further research is imperative to delineate the most optimal dosage, dosing frequency, and total quantity of maintenance infusions required. Additionally, there is a compelling need for studies that explore the impact of RTX on individuals with AIBD who do not exhibit a significant reduction in anti-desmoglein autoantibody levels.

Comprehensive analysis reveals key genes and environmental toxin exposures underlying treatment response in ulcerative colitis based on in-silico analysis and Mendelian randomization

BACKGROUND

UC is increasingly prevalent worldwide and represents a significant global disease burden. Although medical therapeutics are employed, they often fall short of being optimal, leaving patients struggling with treatment non-responsiveness and many related complications.

MATERIALS AND METHODS

The study utilized gene microarray data and clinical information from GEO. Gene enrichment and differential expression analyses were conducted using Metascape and Limma, respectively. Lasso Regression Algorithm was constructed using glmnet and heat maps were generated using pheatmap. ROC curves were used to assess diagnostic parameter capability, while XSum was employed to screen for small-molecule drugs exacerbating UC. Molecular docking was carried out using Autodock Vina. The study also performed Mendelian randomization analysis based on TwoSampleMR and used CTD to investigate the relationship between exposure to environmental chemical toxicants and UC therapy responsiveness.

RESULTS

Six genes (ELL2, DAPP1, SAMD9L, CD38, IGSF6, and LYN) were found to be significantly overexpressed in UC patient samples that did not respond to multiple therapies. Lasso analysis identified ELL2 and DAPP1 as key genes influencing UC treatment response. Both genes accurately predicted intestinal inflammation in UC and impacted the immunological infiltration status. Clofibrate showed therapeutic potential for UC by binding to ELL2 and DAPP1 proteins. The study also reviews environmental toxins and drug exposures that could impact UC progression.

CONCLUSIONS

We used microarray technology to identify DAPP1 and ELL2 as key genes that impact UC treatment response and inflammatory progression. Clofibrate was identified as a promising UC treatment. Our review also highlights the impact of environmental toxins on UC treatment response, providing valuable insights for personalized clinical management.

Diverse Role of OX40 on T Cells as a Therapeutic Target for Skin Diseases

OX40 is an important costimulatory molecule for T-cell expansion and survival. Because OX40 is expressed on most T-cell subsets, it is an attractive therapeutic target for a variety of T-cell‒mediated diseases. Clinical trials are already underway for some skin inflammatory diseases. In this review, we present various observations that improve our understanding of how OX40-targeted therapy can be applied for skin inflammatory diseases, such as atopic dermatitis and psoriasis, T helper (Th)2- and Th17-mediated diseases, respectively. The important OX40/OX40L-mediated interaction between T cells and other immune cells is also discussed in terms of skin autoimmune diseases, such as alopecia areata and pemphigus. Regulatory T cells (Tregs) highly express OX40, and the skin harbors a large Treg population; thus, understanding how OX40-targeted treatment acts on Tregs is vital for the development of therapeutic strategies for various skin diseases.

T cell autoimmunity and immune regulation to desmoglein 3, a pemphigus autoantigen

Pemphigus is a life-threatening autoimmune bullous disease mediated by anti-desmoglein IgG autoantibodies. Pemphigus is mainly classified into three subtypes: pemphigus vulgaris, pemphigus foliaceus, and paraneoplastic pemphigus. The pathogenicity of autoantibodies has been extensively studied. Anti-human CD20 antibody therapy targeting B cells emerged as a more effective treatment option compared to conventional therapy for patients with an intractable disease. On the other hand, autoreactive T cells are considered to be involved in the pathogenesis based on the test results of human leukocyte antigen association, autoreactive T cell detection, and cytokine profile analysis. Research on the role of T cells in pemphigus has continued to progress, including that on T follicular helper cells, which initiate molecular mechanisms involved in antibody production in B cells. Autoreactive T cell research in mice has highlighted the crucial roles of cellular autoimmunity and improved the understanding of its pathogenesis, especially in paraneoplastic pemphigus. The mouse research has helped elucidate novel regulatory mechanisms of autoreactive T cells, such as thymic tolerance to desmoglein 3 and the essential roles of regulatory T cells, Langerhans cells, and other molecules in peripheral tissues. This review focuses on the immunological aspects of autoreactive T cells in pemphigus by providing detailed information on various related topics.

IgG N-Glycosylation from Patients with Pemphigus Treated with Rituximab

Pemphigus is a life-threatening auto-immune blistering disease of the skin and mucous membrane that is caused by the production of auto-antibodies (auto-Abs) directed against adhesion proteins: desmoglein 1 and 3. We demonstrated in the “Ritux3” trial, the high efficacy of rituximab, an anti-CD20 recombinant monoclonal antibody, as the first-line treatment for pemphigus. However, 25% of patients relapsed during the six-month period after rituximab treatment. These early relapses were associated with a lower decrease in anti-desmoglein auto-Abs after the initial cycle of rituximab. The N-glycosylation of immunoglobulin-G (IgG) can affect their affinity for Fc receptors and their serum half-life. We hypothesized that the extended half-life of Abs could be related to modifications of IgG N-glycans. The IgG N-glycome from pemphigus patients and its evolution under rituximab treatment were analyzed. Pemphigus patients presented a different IgG N-glycome than healthy donors, with less galactosylated, sialylated N-glycans, as well as a lower level of N-glycans bearing an additional N-acetylglucosamine. IgG N-glycome from patients who achieved clinical remission was not different to the one observed at baseline. Moreover, our study did not identify the N-glycans profile as discriminating between relapsing and non-relapsing patients. We report that pemphigus patients present a specific IgG N-glycome. The changes observed in these patients could be a biomarker of autoimmunity susceptibility rather than a sign of inflammation.

FcRn Antagonism Leads to a Decrease of Desmoglein-Specific B Cells: Secondary Analysis of a Phase 2 Study of Efgartigimod in Pemphigus Vulgaris and Pemphigus Foliaceus

Background

Immunoglobulin G (IgG) levels are maintained by the IgG-recycling neonatal Fc-receptor (FcRn). Pemphigus vulgaris and pemphigus foliaceus are debilitating autoimmune disorders triggered by IgG autoantibodies against mucosal and epidermal desmogleins. Recently, a phase 2 clinical trial (NCT03334058; https://clinicaltrials.gov/NCT03334058) was completed in participants with pemphigus using efgartigimod, an FcRn inhibitor, in combination with prednisone. Efgartigimod demonstrated an early effect on diease activity and was well tolerated. In addition to the safety and efficacy assessment, clinical trials present an opportunity to gain more insights into the mechanism of disease, the mode of action of treatment, and potential for corticosteroid-sparing activity.

Objective

The aim of our study was to assess the impact of FcRn antagonism by efgartigimod on immunological parameters known to be directly involved in pemphigus pathology, such as cellular and serological responses.

Methods

We investigated total and antigen-specific IgG subclass level kinetics during and after treatment, assessed antigen-specific B-cell responses, followed T- and B-cell immunophenotypes, and analyzed how different immunophenotypes link to clinical response.

Results

Treatment resulted in reduction of total IgG as well as autoreactive IgG antibody levels. Surprisingly, unlike total IgG and vaccine- or natural-infection-elicited IgG, which returned to baseline levels after stopping efgartigimod treatment, autoreactive antibody levels remained low in several study participants. Efgartigimod showed no effect on total leukocytes, neutrophils, monocytes, or lymphocytes in patients treated with extended efgartigimod therapy. Intriguingly, antigen-specific analyses revealed a loss of desmoglein-specific B cells in several participants responding to efgartigimod, in line with prolonged reduction of pathogenic IgG levels.

Conclusions

Efgartigimod treatment of participants with pemphigus improved their conditions and exerted an immunomodulatory effect beyond the blockade of IgG recycling. Further studies in larger populations with an appropriate placebo control are needed to confirm these potentially important observations to establish long-term clinical responses in autoimmune diseases.

Transcriptomic profiling of pemphigus lesion infiltrating mononuclear cells reveals a distinct local immune microenvironment and novel lncRNA regulators

Pemphigus is an autoimmune skin disease. Ectopic lymphoid-like structures (ELSs) were found to be commonly present in the pemphigus lesions, presumably supporting in situ desmoglein (Dsg)-specific antibody production. Yet functional phenotypes and the regulators of Lymphoid aggregates in pemphigus lesions remain largely unknown. Herein, we used microarray technology to profile the gene expression in skin lesion infiltrating mononuclear cells (SIMC) from pemphigus patients. On top of that, we compared SIMC dataset to peripheral blood mononuclear cells (PBMC) dataset to characterize the unique role of SIMC. Functional enrichment results showed that mononuclear cells in skin lesions and peripheral blood both had over-represented IL-17 signaling pathways while neither was characterized by an activation of type I Interferon signaling pathways. Cell-type identification with relative subsets of known RNA transcripts (CIBERSORT) results showed that naïve natural killer cells (NK cells) were significantly more abundant in pemphigus lesions, and their relative abundance positively correlated with B cells abundance. Meanwhile, plasma cells population highly correlated with type 1 macrophages (M1) abundance. In addition, we also identified a lncRNA LINC01588 which might epigenetically regulate T helper 17 cells (Th17)/regulatory T cells (Treg) balance via the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Here, we provide the first transcriptomic characterization of lesion infiltrating immune cells which illustrates a distinct interplay network between adaptive and innate immune cells. It helps discover new regulators of local immune response, which potentially will provide a novel path forward to further uncover pemphigus pathological mechanisms and develop targeted therapy.

The Diversity of Serum Anti-DSG3 IgG Subclasses Has a Major Impact on Pemphigus Activity and Is Predictive of Relapses After Treatment With Rituximab

Introduction

We studied the distribution and in vitro pathogenicity of anti-DSG3 IgG subclasses during the course of pemphigus vulgaris (PV).

Methods

We longitudinally studied the distribution of anti-DSG3 IgG subclasses (before versus after treatment) in sera from PV patients, using an addressable-laser bead immunoassay (ALBIA). The in vitro pathogenicity of corresponding sera was tested using keratinocyte dissociation and immunofluorescence assays.

Results

Sixty-five sera were assessed at baseline (33 from patients treated with rituximab and 32 with corticosteroids). Sixty-three percent of these baseline sera contained 2 or more anti-DSG3 IgG subclasses versus 35.7% of sera from patients in complete remission (CR) and 75.0% of sera from patients with persistent disease activity after treatment. IgG4 was the most frequently detected anti-DSG3 IgG subclass, both in patients with disease activity and in those in CR. The presence of three or more anti-DSG3 IgG subclasses was predictive of relapse, in particular when it included IgG3, with a positive predictive value of 62.5% and a negative predictive value of 92%. While anti-DSG3 IgG4 Abs from sera collected before treatment were most often pathogenic, anti-DSG3 IgG4 from sera collected after treatment were pathogenic only after adjusting their titer to the one measured before treatment. The IgG3 fraction containing anti-DSG3 Abs also had an in vitro pathogenic effect. The disappearance of the pathogenic effect of some sera after removal of anti-DSG3 IgG3 suggested an additional effect of this IgG subclass.

Conclusion

The serum levels and number of anti-DSG3 IgG subclasses drive the pathogenic effect of pemphigus sera and may predict the occurrence of relapses.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

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

Longitudinal Pathogenic Properties and N-Glycosylation Profile of Antibodies from Patients with Pemphigus after Corticosteroid Treatment

Pemphigus vulgaris is an autoimmune disease that occurs due to pathogenic autoantibodies that recognize the following epidermal adhesion proteins: desmogleins. Systemic corticosteroids usually decrease the titers of anti-desmoglein autoantibodies and improve patients’ conditions. Since modifications of IgG N-glycosylation have been described in some autoimmune diseases, we hypothesized that changes in the pathogenic activity of pemphigus IgG could be related to changes in their N-glycosylation profile. The purpose of this study was to assess, longitudinally, the pathogenicity of pemphigus serum IgG and their N-glycosylation profile during phases of disease activity and clinical remission. The pathogenic activity of serum IgG was measured in vitro on immortalized keratinocytes, by immunofluorescence and dissociation assays, and IgG N-glycans were analyzed by mass spectrometry. We showed (i) a correlation between pemphigus clinical activity and the pathogenicity of serum IgG at baseline and at month 6, while the persistence of the in vitro pathogenic activity of IgG during its evolution, even in patients in clinical remission, seemed to be predictive of relapse; (ii) that modifications of the N-glycan structure were altered the in vitro pathogenicity of patients’ autoantibodies; (iii) that the pathogenic properties of pemphigus IgG did not appear to be related to the disparity in IgG N-glycans during the course of pemphigus.

Autoantibody-Specific Signalling in Pemphigus

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