Targeted Therapies for Autoimmune Bullous Diseases: Current Status

Treatment and molecular analysis of bullous pemphigoid with tofacitinib: a case report and review of current literature

Background

Bullous pemphigoid (BP) is a rare, life-threatening autoimmune blistering disease with pruritus and tension blisters/bullous as the main clinical manifestations. Glucocorticosteroids are the main therapeutic agents for it, but their efficacy is poor in some patients. Tofacitinib, a small molecule agent that inhibits JAK1/3, has shown incredible efficacy in a wide range of autoimmune diseases and maybe a new valuable treatment option for refractory BP.

Objective

To report a case of refractory BP successfully treated with tofacitinib, then explore the underlying mechanism behind the treatment, and finally review similarities to other cases reported in the literature.

Methods

Case report and literature review of published cases of successful BP treatment with JAK inhibitors. The case report describes a 73-year-old male with refractory BP that was successfully managed with the combination therapy of tofacitinib and low-dose glucocorticoids for 28 weeks. Immunohistochemistry and RNA sequencing were performed to analyze the underlying mechanism of tofacitinib therapy. A systematic literature search was conducted to identify other cases of treatment with JAK inhibitors.

Results

Throughout the 28-week treatment period, the patient experienced clinical, autoantibody and histologic resolution. Immunohistochemical analysis showed tofacitinib significantly decreased the pSTAT3 and pSTAT6 levels in the skin lesions of this patient. RNA sequencing and immunohistochemical testing of lesion samples from other BP patients identified activation of the JAK-STAT signaling pathway. Literature review revealed 17 previously reported cases of BP treated with four kinds of JAK inhibitors successfully, including tofacitinib (10), baricitinib (1), upadacitinib (3) and abrocitinib (3).

Conclusions

Our findings support the potential of tofacitinib as a safe and effective treatment option for BP. Larger studies are underway to better understand this efficacy and safety.

Mechanisms of Resistance to Rituximab Used for the Treatment of Autoimmune Blistering Diseases

Autoimmune blistering diseases represent a group of chronic severe, disabling, and potentially fatal disorders of the skin and/or mucous membranes, primarily mediated by pathogenic auto-antibodies. Despite their rarity, these diseases are associated with significant morbidity and mortality and profound negative impact on the patient's quality of life and impose a considerable economic burden. Rituximab, an anti-CD-20 monoclonal antibody, represents the first line of therapy for pemphigus, regardless of severity and a valuable off-label therapeutic alternative for subepidermal autoimmune blistering diseases as it ensures high rates of rapid, long-lasting complete remission. Nevertheless, disease recurrence is the rule, all patients requiring maintenance therapy with rituximab eventually. While innate resistance to rituximab in pemphigus patients is exceptional, acquired resistance is frequent and may develop even in patients with initial complete response to rituximab, representing a real challenge for physicians. We discuss the various resistance mechanisms and their complex interplay, as well as the numerous therapeutic alternatives that may be used to circumvent rituximab resistance. As no therapeutic measure is universally efficient, individualization of rituximab treatment regimen and tailored adjuvant therapies in refractory autoimmune blistering diseases are mandatory.

Efficacy and safety of adjuvant immunoadsorption in pemphigus vulgaris and pemphigus foliaceus (IA-Pem Study): a multicentre randomized controlled trial

BACKGROUND

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are potentially life-threatening autoimmune blistering diseases. Treatment is based on long-term immunosuppression with high doses of glucocorticosteroids in combination with potentially corticosteroid-sparing agents and/or rituximab. Immunoadsorption (IA) has emerged as a fast-acting adjuvant treatment option.

OBJECTIVES

To assess the clinical efficacy of IA in addition to best medical treatment (BMT).

METHODS

We conducted a multicentre (26 centres from Germany and Austria) randomized controlled trial in 72 patients with newly diagnosed, relapsed or chronic active PV or PF (34 female patients and 38 male patients, aged 42-72 years) comparing BMT (prednisolone 1.0 mg kg-1 per day plus azathioprine or mycophenolate) with adjuvant IA (BMT + IA). Central 1 : 1 randomization was done at the coordinating centre for clinical trials (KKS Marburg). The primary endpoint was analysed using Kaplan-Meier and Cox regression methods.

RESULTS

The study was ended prematurely owing to safety concerns after random allocation of 72 patients to BMT + IA (n = 34) or BMT (n = 38). The primary endpoint, time to complete remission on therapy, was not significantly different for the two groups [hazard ratio (HR) 1.35, 95% confidence interval (CI) 0.68-2.69; P = 0.39]. The cumulative dose of prednisolone was significantly lower in the BMT + IA group compared with BMT alone (difference -1214, 95% CI -2225 to -70; P = 0.03). In a post hoc analysis, patients with more extensive PV/PF showed a tendency towards a shorter time to remission in the BMT + IA group compared with the BMT group (HR 1.87, P = 0.17 in patients with baseline Pemphigus Disease Area Index ≥ 15). While more adverse events were observed in patients in the BMT group (29 vs. 25), severe adverse events were more frequent in patients in the BMT + IA group (17 events in 10 patients vs. 11 events in 8 patients).

CONCLUSIONS

In this study, adjuvant IA did not demonstrate a shorter time to clinical remission, but a corticosteroid-sparing effect was observed. In patients with extensive PV/PF, post hoc analysis suggests that adjuvant IA may lead to earlier remission, but potential adverse events must be carefully weighed against the expected benefits.

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.

Advancements in Bullous Pemphigoid Treatment: A Comprehensive Pipeline Update

ABASTRACT

Bullous pemphigoid (BP) is a common autoimmune bullous disease affecting mainly the elderly, with rising incidence due to increased life expectancy. This disease is characterized by tense bullous lesions on normal or erythematous skin, accompanied by pruritus. BP pathogenesis involves autoantibodies against hemidesmosomal proteins BP180 and BP230, leading to detachment at the dermo-epidermal junction as well as blister formation. BP is associated with coexisting comorbidities and drug exposure, and its management often requires high doses or chronic use of systemic glucocorticoids, posing risks of adverse effects. This review focuses on novel treatment options for BP, exploring therapies targeting different immune pathways. Rituximab, a CD20 monoclonal antibody, depletes B-lymphocytes and has shown efficacy in severe cases. Dupilumab, targeting interleukin (IL)-4 receptor α and thus blocking IL-4 and IL-13, downregulates type 2 helper (Th2) responses and has demonstrated promising results. Targeting eosinophil-related molecules using bertilimumab and AKST4290 has yielded positive results in clinical trials. Omalizumab, an immunoglobulin (Ig) E antibody, can reduce disease severity and allows corticosteroid tapering in a number of cases. Complement inhibitors such as nomacopan and avdoralimab are being investigated. IL-17 and IL-23 inhibitors such as secukinumab and tildrakizumab have shown potential in a limited number of case reports. Neonatal Fc receptor antagonists such as efgartigimod are under investigation. Additionally, topical therapies and Janus kinase inhibitors are being explored as potential treatments for BP. These novel therapies offer promising alternatives for managing BP, with potential to improve outcomes and reduce high cumulative doses of systemic corticosteroids and related toxicities. Further research, including controlled clinical trials, is needed to establish their efficacy, safety, and optimal dosing regimens for BP management.

Type 2 T-Cell Responses against Distinct Epitopes of the Desmoglein 3 Ectodomain in Pemphigus Vulgaris

Pemphigus vulgaris (PV) is an autoimmune blistering disorder of the skin and/or mucous membranes caused by IgG autoantibodies that predominantly target two transmembrane desmosomal cadherins: desmoglein (DSG)1 and DSG3. DSG-specific T cells play a central role in PV pathogenesis because they provide help to autoreactive B cells for autoantibody production. In this study, we characterized DSG3-specific peripheral T cells in a cohort of 52 patients with PV and 41 healthy controls with regard to cytokine profile and epitope specificity. By ELISpot analysis, type 2 T cells reactive with the DSG3 ectodomain were significantly increased in patients with PV compared with those in healthy controls. By dextramer analysis, CD4+ T cells specific for an epitope within the extracellular domain of DSG3, DSG3(206-220), were found at significantly higher frequencies in patients with PV than in HLA-matched healthy controls. T-cell recognition of two distinct DSG3 epitopes, that is, DSG3(206-220) and DSG3(378-392), correlated significantly, suggesting a synergistic effect in B-cell help. Immunization of HLA-DRB1∗04:02-transgenic mice with PV with the same set of DSG3 peptides induced pathogenic DSG3-specific IgG antibodies, which induced loss of keratinocyte adhesion in vitro. Thus, DSG3 peptide-specific T cells are of particular interest as surrogate markers of disease activity and potential therapeutic targets in PV.

Omalizumab in the treatment of bullous pemphigoid resistant to first-line therapy: a French national multicentre retrospective study of 100 patients

BACKGROUND

Interest in the use of omalizumab to treat bullous pemphigoid (BP) in the event of resistance or contraindication to conventional therapies is currently based on limited evidence.

OBJECTIVES

To assess the effectiveness and safety of omalizumab in BP and to identify predictive factors in response to treatment.

METHODS

We conducted a French national multicentre retrospective study including patients with a confirmed diagnosis of BP treated with omalizumab after failure of one or several treatment lines. We excluded patients with clinically atypical BP, as per Vaillant's criteria. The criteria for clinical response to omalizumab were defined according to the 2012 international consensus conference. Anti-BP180-NC16A IgE enzyme-linked immunosorbent assay was performed on sera collected before initiating omalizumab, when available.

RESULTS

Between 2014 and 2021, 100 patients treated in 18 expert departments were included. Median age at diagnosis was 77 years (range 20-98). Complete remission (CR) was achieved in 77% of patients, and partial remission in an additional 9%. CR was maintained 'off therapy' in 11.7%, 'on minimal therapy' in 57.1%, and 'on non-minimal therapy' in 31.2%. Median time to CR was 3 months (range 2.2-24.5). Relapse rate was 14%, with a median follow-up time of 12 months (range 6-73). Adverse events occurred in four patients. CR was more frequently observed in patients with an increased serum baseline level of anti-BP180-NC16A IgE (75% vs. 41%; P = 0.011). Conversely, urticarial lesions, blood total IgE concentration or eosinophil count were not predictive of CR. Patients with an omalizumab dosage > 300 mg every 4 weeks showed a similar final outcome to those with a dosage ≤ 300 mg every 4 weeks, but control of disease activity [median 10 days (range 5-30) vs. 15 days (range 10-60); P < 0.001] and CR [median 2.4 months (range 2.2-8.2) vs. 3.9 months (range 2.3-24.5); P < 0.001] were achieved significantly faster.

CONCLUSIONS

We report the largest series to date of BP treated by omalizumab and confirm its effectiveness and safety in this indication. Serum baseline level of anti-BP180-NC16A IgE may predict response to treatment.

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

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

Pemphigus and pemphigoids: Clinical presentation, diagnosis and therapy

Pemphigus and pemphigoid are two potentially life-threatening groups of autoimmune diseases, characterized by autoantibodies targeting structural components of desmosomes or hemidesmosomes, respectively. Affected patients typically show itchy/painful plaques or blistering skin lesions and/or impairing mucosal blistering and erosions, which may strongly impact their quality of life. Since the milestone work of Walter Lever in 1953, who differentiated these two groups of diseases by histopathological analysis of the level of antibody-mediated skin cleavage, enormous progresses occurred. Achievements made in laboratory diagnostics now allow to identify antigen specific structural proteins of the skin that are targeted by pathogenic autoantibodies. These progresses were accompanied by an increased understanding of the pathogenesis of these diseases thanks to the establishment of animal models reproducing disease and on studies on skin and blood of affected individuals, which have been leading to novel and disease-specific treatments. Yet, given their phenotypical overlap with more common dermatological diseases, correct diagnosis and appropriate treatment are often delayed, in some cases leading to irreversible sequelae, including organ dysfunction (i.e., loss of vision in mucous membrane pemphigoid). Here, we provide a concise overview of the clinical appearance, diagnosis and therapeutic management of pemphigus and pemphigoid diseases.

Pemphigus- und Pemphigoid-Erkrankungen: Klinik, Diagnostik und Therapie: Pemphigus and pemphigoids: Clinical presentation, diagnosis and therapy

Pemphigus und Pemphigoid sind seltene Autoimmunkrankheiten der Haut mit potenziell lebensbedrohlichem Verlauf. Autoantikörper gegen epidermale und junktionale Strukturproteine (Desmosomen sowie Hemidesmosomen) führen bei Betroffenen typischerweise zu juckenden, schmerzhaften Plaques oder Blasen an der Haut und/oder Blasenbildung und Erosionen der Schleimhäute mit möglicher Einschränkung der Lebensqualität. Seit der bahnbrechenden Arbeit von Walter Lever im Jahr 1953, dem es gelang, mittels histopathologischer Untersuchung diese beiden Krankheitsgruppen anhand des Musters der Antikörper‐vermittelten Blasenbildung zu differenzieren, wurden enorme Fortschritte im Verständnis der Erkrankungen erzielt. Die Errungenschaften in der Labordiagnostik ermöglichten die Identifikation von Zielstrukturen zur präzisen Unterscheidung verschiedener Varianten der bullösen Autoimmunerkrankungen. Diese Fortschritte gingen dank der Entwicklung von Tiermodellen mit einem besseren Verständnis der Pathogenese einher. Außerdem haben Studien an Haut und Blut betroffener Patienten zu neuen und krankheitsspezifischen Behandlungen geführt. Aufgrund ihrer Seltenheit und der klinischen Ähnlichkeit mit anderen dermatologischen Erkrankungen verzögern sich die korrekte Diagnosestellung und die Einleitung einer entsprechenden Therapie häufig, was in einigen Fällen zu irreversiblen Folgeerscheinungen, einschließlich Funktionsstörungen von Organen (zum Beispiel Verlust des Sehvermögens beim Schleimhautpemphigoid) führt. Wir geben hier einen Überblick über das klinische Erscheinungsbild, den Diagnosealgorithmus und das therapeutische Management von Pemphigus‐ und Pemphigoid‐Erkrankungen.

Concurrent bullous pemphigoid and psoriasis vulgaris successfully treated with Janus kinase inhibitor tofacitinib: A case report and review of the literature

Bullous pemphigoid (BP) and psoriasis are both immune-related skin diseases. Still, the comorbidities between the two are rare, and there is no consensus on the optimal treatment strategy for BP combined with psoriasis. JAK inhibitors are emerging, molecularly targeted therapeutic agents that target the molecule of Janus kinase, a signal transducer and activator of transcription (JAK/STAT). JAK inhibitors block intracellular signaling pathways by blocking the gene transcription of key pro-inflammatory cytokines that play a central role in the pathogenesis of many inflammatory and autoimmune diseases. Tofacitinib is a first-generation JAK inhibitor. The purpose of this article is to describe the first report of the use of tofacitinib in treating BP combined with psoriasis vulgaris with significant results. According to our findings, tofacitinib may be a safe and effective treatment option for patients suffering from BP and psoriasis together. The implications of this are substantial for the guidance of treatment strategies for both comorbid conditions.

Janus kinase inhibitors in autoimmune bullous diseases

Autoimmune bullous disease (AIBD) is a severe skin disorder caused by autoantibodies that target intercellular or cell-matrix adhesion proteins. Currently, the preferred treatment for AIBD involves the use of glucocorticoids or traditional immunosuppressants. Additionally, the utilization of biological agents such as rituximab, omalizumab, and dupilumab is on the rise. However, effectively managing AIBD remains a challenge. The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway has been implicated in various inflammatory diseases. In recent years, a range of drugs known as JAK inhibitors, which target this pathway, have been developed. Several studies have explored the efficacy and safety of JAK inhibitors for treating AIBD. Consequently, this review begins by examining the role of the JAK/STAT pathway in AIBD, summarizing the application of different JAK inhibitors in AIBD treatment, and emphasizing the importance of disease management in treating AIBD with JAK inhibitors. Furthermore, it highlights the need for a better understanding of the JAK/STAT pathway's role in AIBD, as well as the effectiveness and safety of JAK inhibitors for treating this disease.

Case report: Bullous pemphigoid associated with sintilimab therapy for pMMR/MSS colorectal cancer

Immunotherapy has become a very effective treatment for many cancers. It has a unique set of immune system-related adverse effects, collectively known as immune-related adverse events (irAEs). Skin toxicities are the most common irAEs, of which bullous pemphigoid, although rare, is potentially life-threatening and affects patients’ survival. In this article, we report the treatment of bullous pemphigoid caused by programmed cell death protein-1 (PD-1) in a case of proficient mismatch repair (pMMR)/microsatellite stable (MSS) colorectal cancer. No significant adverse effects were observed in the patient after methylprednisone was tapered to 4 mg twice a day. No new skin lesions occurred recently in the patient and the original skin lesions healed. In particular, the patient’s immunotherapy was not stopped and the best outcome was a partial remission of the disease, lasting for more than 8 months.

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

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

IgG against the Membrane-Proximal Portion of the Desmoglein 3 Ectodomain Induces Loss of Keratinocyte Adhesion, a Hallmark in Pemphigus Vulgaris

Pemphigus vulgaris is a severe autoimmune blistering disease characterized by IgG autoantibodies (auto-abs) against the desmosomal adhesion molecules desmoglein (DSG) 3 and DSG1. Underlying mechanisms leading to blister formation upon binding of DSG-specific IgG auto-abs are not fully understood. Numerous studies showed the pathogenicity of IgG auto-ab binding to the aminoterminal region 1 (EC1) of the DSG3 ectodomain. However, auto-abs in pemphigus vulgaris are polyclonal, including IgG against both aminoterminal- and membrane-proximal epitopes of the DSG3 ectodomain. In this study, the pathogenicity of a previously uncharacterized murine monoclonal IgG antibody, 2G4, directed against the membrane-proximal region (EC5) of the DSG3 ectodomain was characterized and tested in various specificity and functionality assays. The results clearly show that 2G4 is capable of inhibiting intercellular keratinocyte adhesion and of inducing cellular DSG3 redistribution by activation of the p38MAPK signal transduction pathway. In this study, we provide evidence that an IgG auto-abs directed against the membrane-proximal region EC5 of DSG3 induces acantholysis, the hallmark in pemphigus vulgaris. These findings challenge the current concept that IgG auto-abs targeting the NH₂-terminal portion of the DSG3 ectodomain are pathogenic only. Our study provides further aspects for a deeper understanding of desmosomal keratinocyte adhesion and improves our insight into the complex auto-ab‒induced blister formation in pemphigus vulgaris.

Off-Label Uses of Rituximab in Dermatology

Purpose of Review

Rituximab has transformed the treatment of B-cell malignancies and rheumatoid arthritis in the past 2 decades. More recently, this anti-CD20 monoclonal antibody has seen increasing usage in the field of dermatology. This review highlights the evidence supporting its use in several important dermatologic conditions.

Recent Findings

Key recent findings include the 2018 FDA approval of rituximab for the treatment of moderate-to-severe pemphigus.

Summary

Data from randomized controlled trials have demonstrated the efficacy of rituximab in pemphigus, ANCA-associated vasculitis, and cryoglobulinemic vasculitis. More limited data suggests its use in recalcitrant cases of diseases such as pemphigoid, epidermolysis bullosa acquisita, and dermatomyositis. There is scarce evidence and mixed results for rituximab when studied in cutaneous polyarteritis nodosa and cutaneous lupus erythematosus.

Low SOCS3 expression in CD4+ T cells from pemphigus vulgaris patients enhanced Th1- and Th17-cell differentiation and exacerbated acantholysis via STAT activation

OBJECTIVE

Pemphigus vulgaris (PV) is a chronic inflammatory autoimmune blistering disease. Aberrant SOCS3/STAT pathway activation is associated with many autoimmune diseases. This study explored the relationship between activation of the SOCS3/STAT pathway and abnormally increased proportions of Th1 and Th17 cells in the peripheral blood of PV patients as well as the effect of CD4⁺ T cells with abnormal SOCS3/STAT pathway activation on acantholysis.

METHODS

In PV patients, the proportions of Th1 and Th17 cells in peripheral blood, the levels of IFN-γ and IL-17 in serum and the mRNA levels of SOCS3 and STAT1/3 in CD4⁺ T cells were detected. Then, SOCS3-knockdown primary CD4⁺ T cells were prepared, and cocultured with HaCaT cells. Finally, after SOCS3 knockdown and coculture, CD4⁺ T cells were collected, and the proportions of Th1 and Th17 cells, the protein levels of STAT1/3 and p-STAT1/3, and the levels of IFN-γ and IL-17 were measured. After 2 days of coculture, HaCaT cells were collected, inflammatory factors mRNA expression and acantholysis were assessed.

RESULTS

In PV patients, the proportions of Th1 (P = 0.016) and Th17 (P = 0.045) cells and the levels of IFN-γ (P = 0.010) were significantly increased. SOCS3 mRNA in CD4⁺ T cells was significantly decreased (P = 0.008), whereas STAT1 (P = 0.043) and STAT3 (P = 0.004) mRNA were significantly increased. After SOCS3 knockdown, the proportions of Th1 (P < 0.001) and Th17 (P = 0.006) cells, the levels of IFN-γ (P < 0.001) and IL-17 (P = 0.001), and the protein levels of p-STAT1 (P = 0.001) and p-STAT3 (P = 0.003) were significantly increased in the CD4⁺ T-shSOCS3-1 group. In the coculture system, the proportions of Th1 (P < 0.001) and Th17 (P < 0.001) cells, the levels of IFN-γ (P < 0.001) and IL-17 (P < 0.001), and the number of cell fragments (P < 0.001) were significantly increased in the CD4⁺ T-shSOCS3-1+HaCaT-PV-IgG group, whereas the protein level of desmoglein3 (Dsg3) was significantly decreased. In addition, PV-IgG significantly increased IFN-γ and IL-6 mRNA in HaCaT cells.

CONCLUSION

Low SOCS3 expression in CD4⁺ T cells from PV patients leads to overactivation of STAT, which causes CD4⁺ T cells to overdifferentiate into Th1 and Th17 cells. Additionally, PV-IgG-induced local inflammation in skin lesions, which is mediated by IFN-γ and IL-6, can aggravate this phenomenon. Furthermore, low SOCS3 expression in CD4⁺ T cells further exacerbates PV-IgG-induced acantholysis. Therefore, upregulating the expression of SOCS3 in CD4⁺ T cells of PV patients and maintaining the balance of the IFN-γ/STAT1/SOCS3 and IL-6/STAT3/SOCS3 pathways can alleviate acantholysis in patients with PV.

Rituximab in Mucous Membrane Pemphigoid: A Monocentric Retrospective Study in 10 Patients with Severe/Refractory Disease

Rituximab (RTX) is a monoclonal antibody directed against CD20 antigen indicated in an increasing number of immune-mediated diseases. While its efficacy in pemphigus vulgaris has been widely investigated, only a few data about its possible role in pemphigoid diseases have been reported in the literature. Accordingly, herein we evaluated a case series of patients with mucous membrane pemphigoid (MMP) treated with RTX. We included patients with a history of severe/refractory MMP who received at least one cycle of intravenous RTX between May 2018 and December 2021 and had 6 months of follow-up time. Disease control (DC) was our early endpoint, while complete remission (CR) and partial remission (PR) were late endpoints. CR off-therapy, relapses, and adverse events were evaluated as well. Our population included 10 MMP patients. Eight out of ten patients (80%) achieved DC in a mean of 8 weeks, while two patients with ocular MMP were non-responders. Among the eight patients who achieved DC, two reached CR off therapy, two CR on minimal therapy, and two achieved PR on minimal therapy. In our case series, the addition of RTX to conventional therapies was demonstrated to be safe and effective in reaching rapid disease control in the majority of refractory MMP patients.

Unmet Medical Needs in Chronic, Non-communicable Inflammatory Skin Diseases

An estimated 20-25% of the population is affected by chronic, non-communicable inflammatory skin diseases. Chronic skin inflammation has many causes. Among the most frequent chronic inflammatory skin diseases are atopic dermatitis, psoriasis, urticaria, lichen planus, and hidradenitis suppurativa, driven by a complex interplay of genetics and environmental factors. Autoimmunity is another important cause of chronic skin inflammation. The autoimmune response may be mainly T cell driven, such as in alopecia areata or vitiligo, or B cell driven in chronic spontaneous urticaria, pemphigus and pemphigoid diseases. Rare causes of chronic skin inflammation are autoinflammatory diseases, or rheumatic diseases, such as cutaneous lupus erythematosus or dermatomyositis. Whilst we have seen a significant improvement in diagnosis and treatment, several challenges remain. Especially for rarer causes of chronic skin inflammation, early diagnosis is often missed because of low awareness and lack of diagnostics. Systemic immunosuppression is the treatment of choice for almost all of these diseases. Adverse events due to immunosuppression, insufficient therapeutic responses and relapses remain a challenge. For atopic dermatitis and psoriasis, a broad spectrum of innovative treatments has been developed. However, treatment responses cannot be predicted so far. Hence, development of (bio)markers allowing selection of specific medications for individual patients is needed. Given the encouraging developments during the past years, we envision that many of these challenges in the diagnosis and treatment of chronic inflammatory skin diseases will be thoroughly addressed in the future.

Clinical Effectiveness and Safety of Initial Combination Therapy with Corticosteroids and Rituximab in Bullous Pemphigoid: A Retrospective Cohort Study

BACKGROUND

Rituximab is a potential initial adjuvant therapy for bullous pemphigoid, yet clinical experience is scarce.

OBJECTIVE

We aimed to examine the clinical outcomes and safety of initial combination therapy with systemic corticosteroids and adjuvant rituximab for the treatment of bullous pemphigoid.

METHODS

A retrospective cohort study was performed on 84 patients with bullous pemphigoid, who received systemic corticosteroids with or without initial adjuvant rituximab therapy (defined as rituximab use within 12 weeks after initiation of systemic corticosteroids).

RESULTS

Among the 84 patients included (37 received systemic corticosteroids with rituximab and 47 were treated with systemic corticosteroids without rituximab), the median time to complete remission on minimal therapy or off therapy was 215 days (95% confidence interval 176.9-253.1) in patients receiving rituximab vs 529 days (95% confidence interval 338.6-719.4) in those not receiving rituximab. A Cox regression analysis showed an increased probability of reaching complete remission on minimal therapy or off therapy with the combined therapy (hazard ratio = 2.28 [1.28-4.07], p = 0.005) after age, Bullous Pemphigoid Disease Activity Index score, and underlying diseases were controlled. In multivariate logistic/linear regressions, initial adjuvant rituximab therapy was associated with a higher complete remission rate (odds ratio = 6.63 [2.09-21.03]) and lower cumulative prednisolone (mg)/body weight (kg) (B = -24.86 [-44.06 to -8.29]) within 48 weeks. Risk of hospitalization for infection was not elevated in the group treated with adjuvant rituximab.

CONCLUSIONS

Rituximab use as adjuvant therapy within 12 weeks after initiation of systemic corticosteroids was associated with a faster and higher rate of achieving complete remission on minimal therapy or off therapy, as well as a significant corticosteroid-sparing effect and a comparable safety profile in this retrospective study. Hence, initial combination therapy with corticosteroids and adjuvant rituximab could serve as an effective treatment option for bullous pemphigoid, but this requires confirmation in randomized controlled studies.

Rapid Disease Control in First-Line Therapy-Resistant Mucous Membrane Pemphigoid and Bullous Pemphigoid with Omalizumab as Add-On Therapy: A Case Series Of 13 Patients

The role of IgE autoantibodies has been demonstrated in the pathogenesis of bullous pemphigoid for many years. Recently, omalizumab (OMZ), a humanized monoclonal anti-IgE antibody that depletes total serum IgE, has been used off-label in a few case series of bullous pemphigoids demonstrating a rapid efficacy and allowing significant improvements or complete remission as add-on therapy in first-line treatment-resistant patients. Herein, we report the largest retrospective study to evaluate OMZ effectiveness in patients with subepidermal autoimmune blistering diseases. Our series included 13 patients from a single center with bullous pemphigoid or mucous membrane pemphigoid, of whom 7 had mucous membrane involvement. OMZ was added to the unchanged immunosuppressive therapies. Detailed clinical and immunological data during the first year were collected, notably for specific anti-BP180-NC16A IgE and IgG, and the median total follow-up was 30 months (range: 3-81). Our series demonstrated that OMZ induced a significant improvement in pruritus, urticarial score, and daily blister count on day 15, allowing disease control to be achieved in a 1-month median time and complete remission (CR) in a 3-month median time in 85% of these patients previously in therapeutic impasse. At the end of the follow-up, 31% of patients achieved CR on minimal therapy after OMZ weaning without relapses, and 54% achieved CR on OMZ continuation with a minimal dose of concomitant treatment. Two patients experienced therapeutic failure (15%). At baseline, clinical variables reflecting activity were significantly positively correlated with eosinophil blood count, total IgE serum level, specific anti-BP180 IgE and IgG. While baseline anti-BP180 IgG and specific anti-BP180 IgE were significantly positively correlated, only the two patients who experienced a therapeutic failure with OMZ did not fit with this correlation, demonstrating elevated levels of anti-BP180 IgG with no measurable BP180-specific IgE. Follow-up of immunological variables demonstrated a rapid decrease of eosinophilia towards normalization, whereas a slower decline towards negativation was observed over 1 year for anti-BP180 IgG and anti BP180 IgE in patients who responded to OMZ. This case series demonstrated that OMZ is a rapidly effective biologic therapy for refractory bullous pemphigoid and mucous membrane pemphigoid, permitting rapid disease control and reduction of concomitant therapeutics.

Disease progression and response to therapy in pemphigus based on a registry

BACKGROUND AND OBJECTIVES

Pemphigus diseases are potentially life-threatening and rare autoimmune bullous disorders characterized by blisters and erosions of the skin and mucous membranes. These disorders can be largely divided into two major subtypes: pemphigus vulgaris (PV) and pemphigus foliaceus (PF). The objective of this study was to evaluate the autoantibody profile and response to therapy of PV and PF patients by analyzing the clinicopathological data from a registry for bullous autoimmune dermatoses.

PATIENTS AND METHODS

In a retrospective study, data from 69 patients with PV and PF were included in the analysis. The Autoimmune Bullous Skin Intensity Score (ABSIS) was used to assess the clinical course, remissions, relapses and severity of the disease at first manifestation and throughout the observation period. ELISA was performed to assess levels of anti-desmoglein (Dsg)-1 and anti-Dsg3 IgG serum autoantibodies.

RESULTS

The mean remission time in PV and PF patients was 63 weeks. PV patients with mucosal involvement showed a more favorable healing process. In PV patients with a moderate/high anti-Dsg1 IgG serum level at baseline, anti-Dsg3 IgG levels decreased during the observation period.

CONCLUSIONS

Our study provides additional insights into the clinical course of patients with PV and PF, revealing that a mucosal phenotype is associated with a higher tendency towards remission.

Register-Studie zu Krankheitsentwicklung und Therapieansprechen bei Pemphigus

HINTERGRUND UND ZIELE

Pemphigus gehört zu den seltenen, aber potentiell lebensbedrohlichen Autoimmunerkrankungen. Typisch sind Blasen und Erosionen der Haut und der Schleimhäute. Grundsätzlich unterscheiden wir zwei Subtypen: Pemphigus vulgaris (PV) und Pemphigus foliaceus (PF). In dieser Studie wurden die klinisch-pathologischen Daten aus einem Register für bullöse Autoimmundermatosen analysiert mit dem Ziel, das Autoantikörperprofil und das Therapieansprechen bei Patienten mit PV und PF genauer zu charakterisieren.

PATIENTEN UND METHODEN

In einer retrospektiven Studie wurden die Daten von 69 Patienten mit PV und PF analysiert. Zur Beurteilung des klinischen Verlaufs, der Remissionen und Rezidive sowie des Schweregrads der Krankheit bei Erstmanifestation und während des gesamten Beobachtungszeitraums diente der ABSIS (Autoimmune Bullous Skin Intensity Score) (ABSIS). Mittels ELISA wurden die Spiegel von Anti-Desmoglein (Dsg)-1- und Anti-Dsg- IgG-Autoantikörpern im Serum bestimmt.

ERGEBNISSE

Die mittlere Remissionszeit bei Patienten mit PV und PF betrug 63 Wochen. PV-Patienten mit Schleimhautbeteiligung zeigten eine schnellere Heilung. Bei PV-Patienten mit moderat oder stark erhöhten Anti-Dsg1-IgG-Autoantikörpern im Serum zu Beginn erfolgte im Lauf des Beobachtungszeitraums ein Absinken der Anti-Dsg3-IgG-Spiegel.

SCHLUSSFOLGERUNGEN

Unsere Studie liefert neue Erkenntnisse zum Krankheitsverlauf bei Patienten mit PV und PF und offenbart, dass ein Phänotyp mit Schleimhautbeteiligung eine stärkere Neigung zur Remission aufweist.

Emerging Biomarkers and Therapeutic Strategies for Refractory Bullous Pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disorder in the elderly. Systemic and topical use of glucocorticoids and immunosuppressants has been shown to be effective in most patients. However, refractory BP patients are challenged to clinicians with severe clinical symptoms, resistance to treatment, and high relapse rate. How to predict and assess the refractory and severity of bullous pemphigoid is the key issue in clinical practice, and the urgent need for precision medicine in refractory patients is driving the search for biomarkers and biologics. Recently, some biomarkers, such as the level of specific autoantibodies and released cytokines, have been proposed as the potential parameters to reflect the disease severity and predict the treatment response and relapse of refractory BP. Moreover, new biologics targeting pathogenic antibodies, complement, Th2 axis, eosinophils, and Th17 axis have shown potent efficacy on refractory BP. Here, we review the literature and give an overview of emerging biomarkers and therapeutic strategies for refractory bullous pemphigoid to improve the prognosis of the patient.

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.

Biologics in autoimmune bullous diseases: Current scenario

Autoimmune bullous diseases can be intraepidermal (pemphigus group of disorders) or subepidermal (pemphigoid group of disorders). The treatment of these disorders chiefly comprises corticosteroids and immunosuppressant adjuvants like azathioprine and mycophenolate mofetil. Autoantibodies are the main mediators of these diseases. Rituximab, a chimeric anti-CD20 monoclonal antibody targeting B-cells, has emerged as an excellent treatment option for refractory pemphigus vulgaris in the last decade. Since then, many new biologics have been proposed/explored for managing autoimmune bullous diseases. These hold potential for greater efficacy and lesser adverse effects than conventional immunosuppressants. In this review, we discuss the role of various biologics in the treatment of autoimmune bullous diseases, followed by a brief discussion on the drawbacks to their use and new developments in this area.

Simultaneous immunofluorescence and histology in pemphigus vulgaris using ex vivo confocal laser scanning microscopy

Ex vivo confocal laser scanning microscopy (ex vivo CLSM) provides rapid, high-resolution imaging and immunofluorescence examinations of the excised tissues. We aimed to evaluate the applicability of ex vivo CLSM in histomorphological and direct immunofluorescence (DIF) examination of pemphigus vulgaris (PV). 20 PV sections were stained with fluorescent-labeled anti-IgG and anti-C3 using various dilutions and incubation periods. Subsequently, the determined ideal staining protocol was applied on 20 additional PV and 20 control sections. Ex vivo CLSM identified intraepidermal blisters and acantholytic cells in 80% and 60% of PV patients, respectively. The sensitivity of ex vivo CLSM in detecting intraepidermal fluorescence was 90% both with IgG and C3. The specificity of staining for IgG and C3 was 70% and 90%, respectively. Histomorphological and immunofluorescence features of PV could be detected within the same ex vivo CSLM session showing a comparable performance to conventional histopathology and DIF microscopy.

Case Report: Complete and Fast Recovery From Severe COVID-19 in a Pemphigus Patient Treated With Rituximab

COVID-19 is characterized by a severe pulmonary disease due to severe acute respiratory syndrome (SARS)-CoV-2 infection. For clinicians involved in the management of patients with chronic autoimmune diseases the risk linked to the conditions itself and to drug-induced immunosuppression during the COVID-19 pandemic is a major topic. Pemphigus is a rare autoimmune blistering disease (AIBD) of the skin and mucous membranes caused by autoantibodies to desmosomal components, desmoglein 1 and 3. Among immunosuppressant therapies, rituximab (RTX) is considered a highly effective treatment with a favorable safety profile, but it induces a prolonged B-cell depletion that can lead to higher susceptibility to infections. For this reason, concerns about its use during the pandemic have been raised. We describe a case of a pemphigus patient in which RTX-induced B cell depletion led to the severe inflammatory phase, whereas corticosteroid treatment allowed a favorable outcome.

Redox Enzymes of the Thioredoxin Family as Potential and Novel Markers in Pemphigus

Pemphigus vulgaris (PV) is a severe autoimmune blistering disease affecting both skin and mucous membranes. Its pathogenesis is related to IgG autoantibodies primarily targeting the cellular adhesion protein desmoglein (Dsg) 3, one of the major desmosome components. Impaired redox regulation is considered a major player in the pathogenesis of autoimmune diseases such as pemphigus by enhancing inflammation and breakdown of immunological tolerance by structural protein modifications. Despite many recent advances, local and systemic redox profiles that characterize the immune response in pemphigus are virtually unknown but potentially crucial in further advancing our understanding of redox-dependent modifications that eventually lead to clinical manifestation. Here, we have analyzed the individual expression pattern of four major redox enzymes that are members of the thioredoxin (Trx) fold superfamily (peroxiredoxins (Prxs) 1 and 4, glutaredoxin (Grx) 2, and Trx1) in serum and PBMCs as well as their distribution in the skin of pemphigus patients compared to healthy controls. We show that in groups of five pemphigus patients, Prx1 is upregulated in both serum and PBMCs, while its epithelial distribution remains within the spinous epithelial layer. Expression of Grx2 and Prx4 is both reduced in serum and PBMCs, while their distinct and similar expression in the skin changes from an even distribution throughout the basal layer (healthy) to ubiquitous nuclear localization in pemphigus patients. In PV patients, Trx1 is secreted into serum, and cellular distribution appears membrane-bound and cytosolic compared to healthy controls. We furthermore showed that a 3D ex vivo human skin model can indeed be used to reproduce similar changes in the protein levels and distribution of redox enzymes by application of cold atmospheric plasma. Deciphering the relationship between redox enzyme expression and autoimmunity in the context of pemphigus could be critical in elucidating key pathogenic mechanisms and developing novel interventions for clinical management.

Exploring the role of immunotherapeutic drugs in autoimmune diseases: A comprehensive review

Autoimmune diseases are group of disorders where an immune response is mounted against the self. The prevalence and burden of this well established and recognised entity is on the rise. Irrespective of being a systemic or organ specific autoimmune disorder, the common underlying mechanism of action, is the imbalance in immune system resulting in loss of tolerance to self-antigens. The oral cavity is no alien to these disorders or to their influences. Pemphigus group of lesions, systemic lupus erythematosus, psoriasis and even Sjogren's syndrome are some of the established autoimmune disorders with prominent oral manifestations. Though these diseases are well documented and enumerated, however addressing them is where the dilemma lies. Science, research and discoveries are a crucial part of medical discipline which help in looking beyond the horizon. With the introduction of selective targeted immunotherapies for autoimmune diseases as a treatment modality either in solitary or in combination with the conventional immunosuppressive treatments, are emerging as a promising elixir for patients enduring them. However, being unique, exploration of these biologics from its inception, to its mechanism of action, recognition of its application and evaluation of its safety norms are equally vital. Therefore, this review aims to provide a comprehensive particular on the novel biologics, the immunotherapies in autoimmune disorders targeting the different cells, their receptors or cytokines of the immune system.

Propranolol Off-Target: A New Therapeutic Option in Neutrophil-Dependent Dermatoses?

Epidermolysis bullosa acquisita (EBA) is a rare subepidermal blistering dermatosis characterized by autoantibodies targeting collagen VII (COL7), an essential component of the anchoring fibrils, located in the sublamina densa of the dermal‒epidermal junction. In EBA, tissue-bound autoantibodies cause the recruitment and subsequent activation of neutrophils, which eventually lead to subepidermal blistering through the release of proteases and ROS. Thus, targeting either pathogenic IgG autoantibodies or neutrophil recruitment or activation has shown efficacy in experimental murine EBA models and patients with EBA. In this issue, Stüssel et al. demonstrate that propranolol, a nonselective β-adrenoreceptor blocker, markedly inhibits the neutrophil release of ROS induced by complexes of COL7 and/or anti-COL7 IgG in vitro and ameliorates the formation of blisters and erosions in an antibody passive-transfer model of murine EBA. These findings warrant further investigations aimed at characterizing the therapeutic efficacy of propranolol in EBA and possibly beyond.

Intraepithelial autoimmune bullous dermatoses disease activity assessment and therapy

Intraepithelial autoimmune blistering dermatoses are a rare group of skin disorders characterized by disruptions of inter-keratinocyte connections within the epidermis through the action of autoantibodies. The second article in this continuing medical education series presents validated disease activity scoring systems, serologic parameters of disease, treatments, and clinical trials for pemphigus and its subtypes.

[Paraneoplastic autoimmune dermatoses]

Paraneoplastic skin manifestations associated with malignancies are extremely polymorphous. Clinicians should be familiar with paraneoplastic dermatoses to establish an early diagnosis of the underlying neoplasm. Lack of familiarity with cutaneous clues for internal malignancies may delay diagnosis and treatment of cancer. In this review, we describe several paraneoplastic autoimmune dermatoses, including paraneoplastic autoimmune multiorgan syndrome, paraneoplastic bullous pemphigoid, and paraneoplastic dermatomyositis.

A Glance at the Use of Glucocorticoids in Rare Inflammatory and Autoimmune Diseases: Still an Indispensable Pharmacological Tool?

Since their discovery, glucocorticoids (GCs) have been used to treat almost all autoimmune and chronic inflammatory diseases, as well as allergies and some forms of malignancies, because of their immunosuppressive and anti-inflammatory effects. Although GCs provide only symptomatic relief and do not eliminate the cause of the pathology, in the majority of treatments, GCs frequently cannot be replaced by other classes of drugs. Consequently, long-term treatments cause adverse effects that may, in turn, lead to new pathologies that sometimes require the withdrawal of GC therapy. Therefore, thus far, researchers have focused their efforts on molecules that have the same efficacy as that of GCs but cause fewer adverse effects. To this end, some GC-induced proteins, such as glucocorticoid-induced leucine zipper (GILZ), have been used as drugs in mouse models of inflammatory pathologies. In this review, we focus on some important but rare autoimmune and chronic inflammatory diseases for which the biomedical research investment in new therapies is less likely. Additionally, we critically evaluate the possibility of treating such diseases with other drugs, either GC-related or unrelated.

Novel Therapies for Pemphigus Vulgaris

Pemphigus vulgaris (PV) is a severe chronic autoimmune blistering disease that affects the skin and mucous membranes. It is characterized by suprabasal acantholysis due to disruption of desmosomal connections between keratinocytes. Autoantibodies against desmosomal cadherins, desmoglein 3 and 1, have been shown to induce disease. Certain human leukocyte antigen (HLA) types and non-HLA foci confer genetic susceptibility. Until the discovery of corticosteroids in the 1950s, PV was 75% fatal. Since then, multiple PV treatments, such as systemic corticosteroids and adjunctive therapy with immunosuppressive medications (mycophenolate mofetil, azathioprine, cyclophosphamide, cyclosporine, methotrexate, gold, and others) have been introduced; however, none have led to long-term remissions and many have undesired adverse effects. Our growing understanding of the pathophysiologic mechanisms in PV is leading to development of new targeted therapies, such as intravenous immunoglobulin, anti-CD20 monoclonal antibodies, inhibitors of Bruton tyrosine kinase and neonatal Fc receptors, and adoptive cellular transfer, that may result in lasting control of this life-threatening disease.

Patients with pemphigus are at an increased risk of developing rheumatoid arthritis: a large-scale cohort study

Data regarding the association between pemphigus and rheumatoid arthritis (RA) is inconclusive and yet to be firmly established. In the current study, we aimed to evaluate the risk of developing RA during the course of pemphigus. A large-scale population-based longitudinal cohort study was conducted to evaluate the hazard ratio (HR) of RA among 1985 patients with pemphigus relative to 9874 age-, sex-, and ethnicity-matched control subjects. A multivariate Cox regression model was utilized. The incidence of RA was 1.07 (95% CI, 0.62-1.72) and 0.36 (95% CI, 0.24-0.52) per 1000 person-years among patients with pemphigus and controls, respectively. The lifetime prevalence of RA was 2.3% (95% CI, 1.7-3.1%) among cases and 1.8% (95% CI, 1.5-2.0%) among controls. Patients with pemphigus were more than twice as likely to develop RA as compared to control subjects (adjusted HR, 2.54; 95% confidence interval [CI], 1.31-4.92). The increased risk was robust to a sensitivity analysis that included only cases managed by pemphigus-related systemic medications (adjusted HR, 2.56; 95% CI, 1.30-5.05). In conclusion, pemphigus is associated with an increased risk of RA. Physicians treating patients with pemphigus should be aware of this possible association. Further research is required to better understand the mechanism underlying this association.

Immune serological diagnosis of pemphigus

Pemphigus is a rare autoimmune blistering disease which manifests with painful erosions and blisters of the skin and mucosa. This disorder is caused by autoantibodies attacking desmosomal proteins, necessary for cell-cell contact stability and epidermal integrity. Desmoglein (Dsg) 1 and Dsg3 are the two major target antigens in pemphigus. Yet, many other target proteins, which have been described over the years, seem to be involved in the loss of epidermal integrity. Clinical examination, combined to serological advances and detection of targeted antigens, permitted to differentiate among several pemphigus subtypes, in which pemphigus vulgaris and pemphigus foliaceus are the most common. Nowadays, serological analysis in pemphigus is a fundamental step of the diagnostic algorithm. This is based on analysis of clinical symptoms, histopathological examination of lesional skin, detection of tissue bound and circulating antibodies by direct and indirect immunofluorescence, and determination of target antigens either by enzyme-linked immunosorbent essay (ELISA) or by western blot analysis. A correct and exhaustive diagnostic algorithm is fundamental to characterize pemphigus subtypes, which lastly permits to adopt a correct treatment approach. Moreover, quality and quantity of circulating antibodies in patient's sera deliver important information regarding clinical course, disease severity and treatment response; thus, relevantly affecting physician's decision. To facilitate this process, "easy-to-perform" diagnostic kits with high sensitivity and specificity are being commercialized. In this review, we focus on available methods and established assays to correctly detect circulating autoantibodies in pemphigus. Moreover, we discuss subtype specific serological peculiarities in the five most relevant subtypes (pemphigus vulgaris, pemphigus foliaceus, pemphigus vegetans, paraneoplastic pemphigus and intercellular IgA dermatosis (also called as IgA pemphigus).

Immunophenotyping in pemphigus reveals a TH17/TFH17 cell-dominated immune response promoting desmoglein1/3-specific autoantibody production

BACKGROUND

T_H2 cells were thought to be a pivotal factor for initiation of the autoimmune blistering disease pemphigus. However, the role of other T-cell subsets in pemphigus pathogenesis remained unclear.

OBJECTIVE

We aimed to characterize the exact phenotype of T cells responsible for the development of pemphigus.

METHODS

Whole transcriptome shotgun sequencing was performed to determine differential gene expression in pemphigus lesions and skin of healthy individuals. The cutaneous cytokine signature was further evaluated by real-time quantitative PCR. In peripheral blood, the distribution of T_H cell and folliclular helper (T_FH) cell subsets was analyzed by flow cytometry. Finally, the capacity of T_H and T_FH cell subsets to induce desmoglein (Dsg)-specific autoantibodies by memory B cells was evaluated in coculture experiments.

RESULTS

Transcriptome analysis of skin samples identified an IL-17A-dominated immune signature in patients with pemphigus, and Kyoto Encyclopedia of Genes and Genomes pathway analysis confirmed the dominance of the IL-17A signaling pathway. Increased expression of IL17A and associated cytokines was also detected by real-time quantitative PCR comparing lesional with perilesional or healthy skin. Interestingly, utilization of flow cytometry showed that patients with active pemphigus had elevated levels of circulating IL-17⁺_, T_H17, T_FH17, and T_FH17.1 cells. Notably, levels of T_H17 and T_FH17 cells correlated with levels of Dsg-specific CD19⁺CD27⁺ memory B cells, and patients with acute pemphigus showed higher levels of Dsg3-autoreactive T_FH17 cells. Coculture experiments revealed T_FH17 cells as primarily responsible for inducing Dsg-specific autoantibody production by B cells.

CONCLUSION

Our findings show that T_FH17 cells are critically involved in the pathogenesis of pemphigus and offer novel targets for therapeutic intervention.

Autoreactive T cells in pemphigus: perpetrator and target

Pemphigus vulgaris (PV) is an autoimmune blistering disease, in which autoantibodies against epidermal cadherins, such as desmoglein (Dsg)1 and Dsg3, lead to the development of blisters and erosions on the skin and mucous membranes. Autoreactive CD4+ T cells are essential for the induction and perpetuation of the disease by interaction with B cells producing autoantibodies. PV has a strong genetic association with certain human leucocyte antigen (HLA) alleles with HLA-DRB1*04:02 and LA-DQB1*05:03 being the most prevalent in patients. Recently, genome-wide association studies have provided a new approach to identify single nucleotide polymorphisms, alongside the known association with HLA alleles. Loss of tolerance against Dsgs and other autoantigens is a critical event in the pathogenesis of PV. Epitope spreading contributes to the progression of PV, leading to an extension of the Dsg-specific autoimmune response to other molecular epitopes of autoantigens, such as desmocollins or muscarinic receptors. Alterations in CD4+CD25+ FoxP3+ regulatory T cells are thought to contribute to the development of PV representing a suitable target for therapeutic interventions. Several CD4+ T-cell subsets and cytokines are involved in the pathogenesis of PV, while Th2 cells are the extensively studied population. Recently, other T cell subsets like T follicular helper cells and Th17 have gained attention as new potential players in PV pathogenesis. The involvement of local autoantibody production in the lesional skin of PV patients in tertiary lymphoid organs is currently discussed but not yet clarified. In this study, we reviewed the current knowledge about the development, characteristics and function of autoreactive T cells in pemphigus and present current new T cell-targeted therapeutic approaches.

Case Report: Apremilast for Therapy-Resistant Pemphigus Vulgaris

Background

In pemphigus, elucidating the disease-causing immune mechanism and developing new therapeutic strategies are needed. In this context, the second messenger 3′,5′-cyclic adenosine monophosphate (cAMP) is gaining attention. cAMP is important in hematological and auto-inflammatory disorders. A class of enzymes called phosphodiesterases (PDEs) control intracellular cAMP levels. In pemphigus, cAMP levels increase following IgG binding to Dsg3. This appears to be a mechanism to preserve epithelial integrity.

Objectives

To determine whether apremilast, an inhibitor of the PDE4 normally used in psoriasis, may be of benefit in the blistering skin disorder pemphigus.

Methods

Here we report of a 62 years old patient with chronic debilitating and recalcitrant pemphigus not responding to several previous treatments, who received treatment with apremilast over a period of 32 weeks. Desmoglein autoantibody levels were assessed by Enzyme-linked Immunosorbent Assay (ELISA), whereas disease severity and quality of life were assessed by the Autoimmune Bullous Skin Disorder Intensity Score (ABSIS). In an attempt to explain the effects of apremilast in pemphigus, peripheral blood mononuclear cells (PBMCs) were analyzed for the duration of treatment by flow cytometry for the distribution of specialized T cell subsets. The frequencies of circulating T helper (Th) 1, Th2, Th17, Th17.1 and T follicular helper (Tfh) 1, Tfh2, Tfh17, and Tfh17.1 were analyzed by CCR6, CXCR3, and CXCR5 expression of CD4⁺ T cells. Further, based on the different expressions of CXCR5, CD127, and CD25, we analyzed the T regulatory (Treg) and T follicular regulatory (Tfreg) compartment.

Results

In response to apremilast treatment, Dsg-specific autoantibody titers decreased, blistering ceased and lesions healed, showing a long-lasting effect. While the frequencies of most of the Th and Tfh cell subsets remained unchanged, we observed a continuous increase in Treg and Tfreg cell levels.

Conclusion

Our findings are encouraging and warrant extension of the beneficial effect of PDE4 inhibition on a larger cohort of pemphigus patients.

Therapy of autoimmune mouth bullous disease: 2020 review

Most diseases of oral mucosa are either autoimmune in nature or are the results of immunologically mediated events. The diseases with autoimmune pathogenesis are namely pemphigus and pemphigoid; the oral involvement is frequent or regularly observed in these diseases. The treatments with traditional drugs or biologic agents or combinations of these molecules are employed in clinical practice. New therapeutic targets aim to provide new treatment strategies that may go beyond nonspecific immunosuppression.

Pemphigus Vulgaris and Bullous Pemphigoid: Update on Diagnosis and Treatment

Autoimmune bullous disorders are a heterogeneous spectrum of skin disorders characterized by the production of autoantibodies against adhesion molecules of the skin. The 2 major groups of diseases are "pemphigus diseases" and "autoimmune bullous diseases of the pemphigoid type." Pemphigus diseases are a group of autoimmune blistering diseases of the skin and mucous membranes characterized by intraepithelial cleft and acantholysis. The main subtypes of pemphigus include pemphigus vulgaris, pemphigus foliaceus, and paraneoplastic pemphigus. Diagnosis is based on clinical manifestations and confirmed with histological, immunofluorescence, and serological testing. Recently multivariant enzyme-linked immunosorbent assay systems have been developed as practical screening tools for patients with suspected autoimmune bullous dermatoses. The current first-line treatment of pemphigus is based on systemic corticosteroids that are often combined with immunosuppressive adjuvants, such as azathioprine, mycophenolate mofetil, and the anti-CD20 monoclonal antibody rituximab, usually at initiation of treatment. Rituximab efficacy is higher when it is administered early in the course of the disease. Therefore, it should be used as first-line treatment to improve efficacy and reduce cumulative doses of corticosteroids and their side effects. Treatment of bullous pemphigoid is based on disease extension. Localized and mild forms can be treated with superpotent topical corticosteroids or with nonimmunosuppressive agents. In patients with generalized disease or whose disease is resistant to the treatments described above, systemic corticosteroids are preferred and effective. Adjuvant immunosuppressants are often combined with steroids for their steroid-sparing effect.

Eosinophils in Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disorder with substantial morbidity and mortality. BP is regarded as a disorder driven by IgG due to BP180 and BP230 IgG autoantibodies, yet, new advances highlight the function of eosinophils and IgE autoantibodies in BP. Evidence supports that eosinophils are involved in BP pathogenesis, notably, these include the presence of IL-5, eotaxin, and eosinophil-colony stimulating factor in blister fluid, peripheral blood eosinophilia is present in nearly 50% of affected patients, eosinophils are found against the dermo-epidermal junction (DEJ) when BP serum is present, metalloprotease-9 is secreted by eosinophils at blister sites, blister fluid of BP patients contains eosinophil granule proteins which are located along the lamina lucida of the BMZ in patients with BP and correspond with disease clinically, eosinophil extracellular traps (EET) have been linked to DEJ splitting, IL-5 activated eosinophils cause DEJ separation when BP serum is present, and eosinophils are requisite to drive anti-BP180 IgE mediated blistering of the skin. Yet, the mechanism whereby eosinophils contribute to the pathogenesis of BP remains to be explored. In this review, we examine the role of eosinophils in BP while offering a basis to explain the pathomechanisms of eosinophils in BP.

Autoimmune blistering diseases provoked during the treatment of chronic inflammatory disease with biologic agents: a systematic review

BACKGROUND

To investigate the clinical course of autoimmune blistering diseases (AIBDs) following treatment with biologic agents (BAs) for chronic inflammatory diseases.

METHODS

A comprehensive review of available, published literature was performed using PubMed and CINAHL search engines. Diagnostic criteria of AIBD included positive direct immunofluorescence studies and/or positive serology with clinically suggestive features.

RESULTS

A total of 22 cases of AIBDs provoked by the use of BAs were found. The most commonly implicated agents were tumor necrosis factor-alpha inhibitors (n = 14). The mean age of onset of AIBD was 59.4 years (median 61.5 years, range 31-82). Average time to onset of AIBD following initiation of the suspected BA was 33.7 ± 43.8 weeks (range 3 days to 152 weeks). Psoriasis was the most common associated condition for which the BA was prescribed (n = 11), followed by rheumatoid arthritis (n = 6) and ulcerative colitis (n = 5). Of the 21 cases reporting AIBD outcome, 17 reported remission or complete resolution upon stopping treatment with the involved BA. Four cases reported continued bullae formation without worsening of disease following cessation of the BA or systemic corticosteroids used to treat the AIBD. Five cases rechallenged the patient with the involved BA and four of the five reported recurrence, often with quicker onset and more severe symptoms.

CONCLUSIONS

BAs may be suspected in patients developing AIBD while being treated for chronic inflammatory diseases. A majority of cases resolve upon cessation of the offending agent.