T cell control in autoimmune bullous skin disorders

Oral mucosal lesions in the mouth as first sign of dermatological diseases and disorders

Oral mucosal lesions manifest as a first sign of immune-mediated disorders. Lichen planus, pemphigus and pemphigoid are the most frequent immunologically mediated mucocutaneous diseases with oral involvement. Oral lesions are initially detected by dental health practitioners. Early detection can help in appropriate treatment and better quality of life. Based on an analysis of 6,300 medical records from the period 1997 to 2018, 105 (1.66%) were attributable to these immunologically mediated diseases, of which 86 (1.36%) were due to lichen planus, 4 (0.06%) to pemphigus and 15 (0.23%) to pemphigoid.

HLA-Cw6 Polymorphism in Autoimmune Blistering Diseases

Autoimmune blistering diseases of the pemphigus and pemphigoid groups are immune-mediated disorders due to circulating pathogenetic autoantibodies. Multiple human leukocyte antigen (HLA) genes have been associated with predisposition to these disorders. HLA-Cw6 is involved in antigen presentation processes and has been linked to psoriasis. The aim of our study was to investigate the association between the presence of the HLA-Cw6 allele and susceptibility to pemphigus vulgaris and bullous pemphigoid. A genetic study in vitro with a cross-sectional design was performed enrolling forty patients with pemphigus vulgaris and forty patients with bullous pemphigoid. The detection of HLA-Cw6 was performed through the EUROArray test on DNA obtained from whole blood samples. The polymorphism was detected in 3/40 genotypes in the pemphigus vulgaris group and in 4/40 genotypes of patients with bullous pemphigoid, unveiling a non-statistically significant different frequency in pemphigus (p = 0.6368) and in pemphigoid (p = 0.62) compared to the reference frequency from the literature of 0.086. Further research is needed to better investigate the role of HLA-Cw6 in immune-mediated diseases and to identify novel genetic markers associated with susceptibility to autoimmune blistering diseases and with disease severity and response to immunosuppressive therapies.

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

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

Single-cell sequencing reveals distinct immune cell features in cutaneous lesions of pemphigus vulgaris and bullous pemphigoid

Bullous pemphigoid (BP) and pemphigus vulgaris (PV) are two common subtypes of autoimmune bullous disease (AIBD). The key role of circulating autoreactive immune cells contributing to skin damage of AIBD has been widely recognized. Nevertheless, the immune characteristics in cutaneous lesions remain unclear. Here, we performed single-cell RNA sequencing (scRNA-seq) and single-cell VDJ sequencing (scRNA-seq) to generate transcriptional profiles for cells and T/B cell clonetype in skin lesions of BP and PV. We found that the proportions of NK&T, macrophages/ dendritic cells, B cells, and mast cells increased in BP and PV lesions. Then, BP and PV cells constituted over 75% of all myeloid cell subtypes, CD4+ T cell subtypes and CD8+ T cell subtypes. Strikingly, CD8+ Trm was identified to be expanded in PV, and located in the intermediate state of the pseudotime trajectory from CD8+ Tm to CD8+ Tem. Interestingly, CD8+ Tem and CD4+ Treg highly expressed exhaustion-related genes, especially in BP lesions. Moreover, the enhanced cell communication between stromal cells and immune cells like B cells and macrophages/ dendritic cells was also identified in BP and PV lesions. Finally, clone expansion was observed in T cells of BP and PV compared with HC, while CD8+ Trm represented the highest ratio of hyperexpanded TCR clones among all T cell subtypes. Our study generally depicts a large and comprehensive single-cell landscape of cutaneous lesions and highlights immune cell features in BP and PV. This offers potential research targets for further investigation.

New Onset and Exacerbation of Autoimmune Bullous Dermatosis Following COVID-19 Vaccination: A Systematic Review

BACKGROUND

Cases of autoimmune bullous dermatosis (AIBD) have been reported following COVID-19 vaccination.

OBJECTIVE

We aimed to provide an overview of clinical characteristics, treatments, and outcomes of AIBDs following COVID-19 vaccination.

METHODS

We conducted a systematic review and searched the Embase, Cochrane Library, and Medline databases from their inception to 27 March 2024. We included all studies reporting ≥ 1 patient who developed new-onset AIBD or experienced flare of AIBD following at least one dose of any COVID-19 vaccine.

RESULTS

We included 98 studies with 229 patients in the new-onset group and 216 in the flare group. Among the new-onset cases, bullous pemphigoid (BP) was the most frequently reported subtype. Notably, mRNA vaccines were commonly associated with the development of AIBD. Regarding the flare group, pemphigus was the most frequently reported subtype, with the mRNA vaccines being the predominant vaccine type. The onset of AIBD ranged from 1 to 123 days post-vaccination, with most patients displaying favorable outcomes and showing improvement or resolution from 1 week to 8 months after treatment initiation.

CONCLUSIONS

Both new-onset AIBD and exacerbation of pre-existing AIBD may occur following COVID-19 vaccination. Healthcare practitioners should be alert, and post-vaccination monitoring may be essential.

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.

Role of Human Leukocyte Antigen Class II in Antibody-Mediated Skin Disorders

HLA class II molecules are key factors determining susceptibility to autoimmune disorders, and their role in immune-mediated skin conditions such as psoriasis has been extensively investigated. However, there is currently little understanding of their role in antibody-mediated skin diseases such as autoimmune blistering disorders. We researched the available literature using PubMed to narratively review the current knowledge on HLA associations in antibody-mediated blistering skin pathologies. Our results summarized the risk alleles that are identified in the literature, together with certain known protective alleles: in the pemphigus group, alleles HLA-DQB1*0503 and HLA-DRB1*0402 are most commonly associated with disease; in the pemphigoid group, the most studied allele is HLA-DQB1*0301; in epidermolysis bullosa acquisita, few genetic studies are available; in dermatitis herpetiformis, the association with haplotypes HLA-DQ2 and HLA-DQ8 is strongly established; finally, in linear IgA bullous disease, specific HLA alleles may be responsible for pediatric presentations. Our current pathogenic understanding of this group of disorders assigns a key role to predisposing HLA class II alleles that are able to bind disease autoantigens and therefore stimulate antigen-specific autoreactive T cells. The latter engage B lymphocytes that will produce pathogenic autoantibodies. The distribution of HLA alleles and their disease associations are variable across demographics, and an in-depth pathogenetic understanding is needed to support associations between HLA alleles and disease phenotypes. Additionally, in a personalized medicine approach, the identification of HLA alleles associated with the risk of disease may become clinically relevant in identifying susceptible subjects that should avoid exposure to known triggers, such as medication, when possible.

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.

Immune cells in pemphigus vulgaris and bullous Pemphigoid: From pathogenic roles to targeting therapies

Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are two major subtypes of autoimmune bullous diseases (AIBD), characterized by blisters and erosions of skin and/or mucous membranes with dysregulated immune activity. Current literature established that T and B cells are the main executors of PV and BP. Emerging evidence revealed that macrophages and related cytokines also contribute to these diseases. While the role of lymphocytes on PV and BP is well established, the definitive functions of macrophages in disease progression are not fully understood. Furthermore, current status of clinical trials targeting immune cells is poorly recapitulated in PV and BP. In this review, we summarized current knowledge in this rapidly advancing field, with emphasis on the individual functions of immune cells and their interactions, as well as ongoing clinical trials targeting immune cells, to provide novel insights in mechanistic understanding and clinical management of PV and BP.

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.

HLA class II antigens in Croatian patients with pemphigus vulgaris and their correlation with anti-desmoglein antibodies

Pemphigus vulgaris (PV) is an acquired autoimmune blistering disease characterized by the production of autoantibodies targeting desmosomal cadherins, primarily desmoglein 1 and desmoglein 3, leading to acantholysis. The etiology of PV is multifactorial, including genetic susceptibility. This retrospective study aimed to evaluate the association of HLA class II alleles and PV and to examine the impact of PV-associated HLA class II alleles on the concentration of anti-desmoglein antibodies. The study group included 30 patients in whom the diagnosis of PV was confirmed by histopathological analysis, immunofluorescence findings, and ELISA testing for detecting antibodies against desmoglein 1 and desmoglein 3. HLA class II alleles were typed by polymerase chain reaction with sequence-specific primers (PCR-SSP). The control group consisted of 190 healthy volunteer blood donors. Data analysis revealed a significantly higher frequency of HLA class II alleles in our population of patients with PV, including HLA-DRB1*04:02, HLA-DRB1*14:54, HLA-DQB1*03:02, HLA-DQB1*05:03, HLA- DQA1*03:01, and HLA-DQA1*01:04, as well as a significantly lower frequency of HLA-DQA1*05:01 compared to the control group. We have also investigated the influence of risk alleles for PV, recognized in almost all study populations, HLA-DRB1*04:02 and HLA-DQB1*05:03, on the concentration of antibodies against desmogleins 1 and 3 in relation to the presence of these alleles. The results showed significantly higher levels of antibodies directed against desmoglein 3 among patients with DRB1*04:02 compared to patients without this allele. No difference was found for anti-desmoglein 1 antibodies. Regarding DQB1*05:03 allele, statistical analysis showed no differences in the concentration of anti-desmoglein antibodies in patients carrying this allele versus those without it.

Skin-infiltrating T cells display distinct inflammatory signatures in lichen planus, bullous pemphigoid and pemphigus vulgaris

Introduction

We here thought to dissect the inflammatory signature in lesions of three skin disorders, which show a common adaptive immune response against autoantigens of the skin but are characterized by diverging clinical phenotypes. Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are type-2-dependent, IgG autoantibody-driven blistering disorders of mucous membranes and skin, which target desmoglein (Dsg)3 and bullous pemphigoid (BP)180, respectively. In contrast, lichen planus (LP) is a common chronic inflammatory disease of the skin and mucous membranes with a pronounced dermal T cell infiltrate. We previously identified peripheral type 1 and 17 T cell responses against Dsg3 and BP180 in a cohort of LP patients strongly suggesting that the underlying inflammatory T cell signature may drive the evolving phenotype.

Methods

Paraffin-embedded skin biopsies from well-characterized patients with LP (n=31), BP (n=19), PV (n=9), and pemphigus foliaceus (PF) (n=2) were analysed. Areas with the most prominent inflammatory infiltrate were excised with punch biopsies and tissue microarrays (TMA) containing multiple biopsies were created. Using multicolor immunofluorescence, the inflammatory infiltrate was stained with antibodies against multiple cellular markers, i. e. CD3ϵ, CD4, CD15, TCR-δ, the cytokine IL-17A, and the transcription factors, T-bet and GATA-3.

Results

In LP, there was a higher number of CD4+ T cells expressing T-bet compared to GATA-3. In contrast, CD4+ T cells in PV and BP skin lesions more frequently expressed GATA-3 than T-bet. IL-17A+ cells and IL-17A+ T cells were found to a similar extent in all the three disorders. IL-17A+ granulocytes were more predominant in BP than in LP or PV. Of note, the majority of IL-17A+ cells in LP were neither T cells nor granulocytes.

Discussion

Our findings in inflammatory skin infiltrates clearly show a predominant type 1 signature in LP in contrast to a preponderance of type 2 T cells in PV and BP. In contrast to LP, granulocytes and to a much lesser extent CD3+ T cells were a cellular source of IL-17A in BP and PV. These data strongly suggest that different inflammatory cell signatures drive evolving clinically diverse phenotypes of LP, PV and BP despite common target antigens of the skin.

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.

Researching trends in pemphigoid diseases: A bibliometric study of the top 100 most cited publications

Background

In the field of autoimmune and inflammatory disorders, different approaches were applied to provide information regarding disease activity, comorbidities, epidemiological reports and risk factors. However, no previous studies had thoroughly analyzed the research trend in the field, and the bibliometric analysis focusing on pemphigoid diseases was available. The objective of the current study was to evaluate the current research trend in the field.

Methods

A search has been conducted for the Web of Science database based on various subcategories of pemphigoid diseases. Detailed information including articles' publication types, Author information, citation, and publication information was attained for further analysis.

Results

Within the 6,995 studies, the top 100 most-cited articles were extracted for analysis. Among the top 100 studies, 70% of the studies focused on bullous pemphigoid. More than 60% of the top 100 studies were studies with original data. Furthermore, 30% of the studies were guidelines and narrative reviews. For the issues primarily focused on, most of the high-impact studies described the molecular mechanism of pemphigoid diseases (26%), managements (19%), risk factors of pemphigoid diseases (17%). Additionally, some other studies provided general review or discussed about the issue of epidemiology, diagnosis/definition, comorbidities and clinical characteristics of pemphigoid diseases.

Conclusion

This comprehensive bibliographic study of pemphigoid diseases provided an overview of current research focuses in the field. Topics such as disease management, molecular mechanism of pathogenesis, and drug-inducing pemphigoid diseases were highly mentioned in the most-cited studies. For researchers and clinicians, the researching trend and study focus in the top-100 cited studies could serve as a potential reference for future investigation and patient management.

Association of Rituximab With Risk of Long-term Cardiovascular and Metabolic Outcomes in Patients With Pemphigus

Importance

The association of different therapeutic approaches with long-term cardiovascular and metabolic outcomes in patients with pemphigus remains to be precisely evaluated.

Objective

To assess the risk of long-term cardiovascular and metabolic outcomes and all-cause mortality in patients with pemphigus managed by rituximab compared with those receiving treatment with first-line corticosteroid-sparing agents (azathioprine and mycophenolate mofetil [MMF]).

Design, Setting, and Participants

A global population-based retrospective cohort study compared 961 patients with pemphigus that was managed with rituximab with those treated with azathioprine or MMF (n = 961) regarding the risk of several cardiovascular and metabolic outcomes. Propensity score matching was performed to optimize comparability. Patients were enrolled from the Global Collaborative Network of TriNetX platform.

Main Outcomes and Measures

Risk of myocardial infarction, stroke, peripheral vascular disease, pulmonary embolism, hypertension, hyperlipidemia, type 2 diabetes, obesity, osteoporosis, and avascular bone necrosis.

Results

Of 1602 participants, 855 (53.4%) were women and 747 (46.6%) were men; the mean (SD) age was 54.8 (16.6) years for those treated with rituximab and 54.4 (18.2) years for those treated with azathioprine or MMF. Compared with those treated by azathioprine/MMF, patients treated with rituximab experienced a lower risk of myocardial infarction (relative risk [RR], 0.45; 95% CI, 0.24-0.86; P = .01), stroke (RR, 0.42; 95% CI, 0.26-0.69; P < .001), peripheral vascular disease (RR, 0.47; 95% CI, 0.28-0.79; P = .003), hypertension (RR, 0.48; 95% CI, 0.38-0.63; P < .001), hyperlipidemia (RR, 0.45; 95% CI, 0.32-0.64; P < .001), type 2 diabetes (RR, 0.63; 95% CI, 0.51-0.77; P < .001), obesity (RR, 0.49; 95% CI, 0.34-0.72; P < .001), and osteoporosis (RR, 0.46; 95% CI, 0.30-0.71; P < .001). The all-cause mortality was comparable between patients in both groups (hazard ratio, 0.94; 95% CI, 0.62-1.43; log-rank P = .77).

Conclusions and Relevance

The results of this cohort study suggest that rituximab was associated with protection against long-term cardiovascular and metabolic outcomes compared with conventional immunosuppressants. This agent might be particularly preferred in individuals with preexisting cardiovascular and metabolic risk factors.

Expression of the Selected Proteins of JAK/STAT Signaling Pathway in Diseases with Oral Mucosa Involvement

The JAK/STAT signal pathway is a system of intracellular proteins used by many cytokines and growth factors to express genes responsible for the process of cell activation, proliferation and differentiation. There has been numerous inflammatory and autoimmune diseases identified where the JAK/STAT signaling is disrupted; however, there are only a few papers concerning autoimmune bullous diseases published. The aim of this study was to evaluate the expression of proteins: JAK3, STAT2, STAT4 and STAT6 in epithelium lesions in patients with pemphigus vulgaris (PV), bullous pemphigoid (BP), oral lichen planus (LP) and chronic ulcerative stomatitis (CUS), as well as in the control group. Immunohistochemistry and immunoblotting were used to evaluate expression of selected proteins. We found significantly higher expression of selected JAK/STAT proteins in oral mucosa lesions in study groups in comparison to the control group, which indicates participation of JAK/STAT pathway in pathogenesis of these diseases. In BP and PV there were no increased STAT2 expression, whereas in CUS and LP no increased STAT4 expression occurred. The differences in expression of JAK/STAT proteins in selected disorders have been observed. These results create new potential therapeutic targets for the treatment.

Association of specific HLA alleles and haplotypes with pemphigus vulgaris in the Bulgarian population

Pemphigus vulgaris (PV) is an autoimmune bullous dermatosis with uneven geographic distribution and higher incidence in certain populations. In previous studies, a relatively high incidence of PV was reported in Bulgaria (0.47/100,000/year) comparable to that in other countries. The genetic background was considered responsible for the disease susceptibility, and multiple reports have proven PV to be an HLA-associated condition. The aim of our study was to analyze the role of genetic factors in the development of PV in Bulgaria. HLA genotyping was performed in 56 PV patients, ethnic Bulgarians whose diagnosis was confirmed based on clinical, histological, and immunofluorescent findings. The control group consisted of 204 healthy individuals from the Bulgarian population without evidence for HLA-associated autoimmune diseases. HLA-A,-B,-DRB1,-DQB1 analysis was performed by PCR-SSP. Our results revealed predisposing associations with DRB1*14, DRB1*04:02, and B*38, B*55, while allele DRB1*03:01 and the corresponding haplotypes were significantly decreased in the PV patients. The predisposing role of these alleles has been observed in other populations. All reported predisposing DRB1 alleles have the same amino acids at key positions of the beta chain of the HLA molecules, 26 (Phe), 67 (Leu or Ileu), 70 and 71 (hydrophobic AA: Gln, Arg, Asp, or Glu), and 86 (Val), which is important for the selective presentation of desmoglein 3 peptides. Additionally, specific alleles HLA-A*01 and DRB1*11 were identified with decreased frequencies in the patients’ group, the last one being a common protective allele for autoimmune diseases in the Bulgarian population. The elucidation of the role of genetic factors for the development of pemphigus will help explain its higher incidence and clinical variability in certain populations.

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.

Autoimmune bullous diseases in pregnancy: clinical and epidemiological characteristics and therapeutic approach

Autoimmune bullous dermatoses are a heterogeneous group of diseases with autoantibodies against structural skin proteins. Although the occurrence of autoimmune bullous dermatoses during pregnancy is low, this topic deserves attention, since the immunological and hormonal alterations that occur during this period can produce alterations during the expected course of these dermatoses. The authors review the several aspects of autoimmune bullous dermatoses that affect pregnant women, including the therapeutic approach during pregnancy and breastfeeding. Gestational pemphigoid, a pregnancy-specific bullous disease, was not studied in this review.

Human desmocollin 3-specific IgG antibodies are pathogenic in a humanized HLA-class II transgenic mouse model of pemphigus

Pemphigus is a potentially lethal autoimmune bullous skin disorder, which is associated with IgG autoantibodies against desmoglein 3 (Dsg3) and Dsg1. Notably, a subset of pemphigus patients presents with a similar clinical phenotype in the absence of anti-Dsg IgG, suggesting the presence of serum IgG reactive with desmosomal components other than Dsg1 or Dsg3. We and others have previously shown that such patients have serum IgG autoantibodies against desmocollin 3 (Dsc3), a component of desmosomes, that induce loss of keratinocyte adhesion ex vivo. Moreover, Dsc3 hypomorphic mice show a severe blistering phenotype of the mucous membrane which is highly characteristic in pemphigus. These findings prompted us to study induction and regulation of anti-human Dsc3 IgG in humanized mice transgenic for HLA-DRB1*04:02, which is a highly prevalent haplotype in pemphigus. We show that IgG from sera of immunized mice induce acantholysis in a dispase-based keratinocyte dissociation assay via the activation of p38 mitogen-activated protein kinases and epidermal growth factor receptor. Passive IgG transfer from mice immunized with recombinant human Dsc3 into neonates did not induce intraepidermal loss of adhesion presumably due to the lack of homology between human and mouse Dsc3. Ex vivo stimulation of splenocytes from Dsc3-immunized mice with human Dsc3 leads to a significant proliferative interferon-γ and interleukin 4 T cell response, which is restricted by HLA-DR/DQ. These findings suggest that induction of pathogenic anti-Dsc3 IgG is associated with Dsc3-specific T cells that recognize Dsc3 in association with HLA-DRB1*04:02.

New-Onset Bullous Pemphigoid in a COVID-19 Patient

This manuscript presents a report of bullous pemphigoid rash associated with COVID-19 for the first time. The objective of this manuscript is to present a unique dermatological case in the setting of a COVID-19-positive infection to further recognize the virus symptomatology. A 37-year-old female with a past medical history of class III obesity, type II diabetes mellitus, and hypertension presented to the emergency department in September 2020 with inpatient and outpatient follow-up through to November 2020. The patient denied any personal or family history of skin disorders. The patient tested positive for COVID-19 prior to hospitalization and presented to the hospital with severe, persistent, pruritic rash meeting dermatopathological, serologic, and clinical criteria for bullous pemphigoid diagnosis. Histopathology H&E punch biopsy from her left flexor wrist demonstrated epidermal keratinocyte necrosis, subepidermal vesiculation with eosinophils, gossamer stranding of the papillary dermis, and subepidermal edema. Direct immunofluorescence punch biopsy from her left flexor wrist demonstrated strong linear IgG staining at the dermoepidermal junction, with weaker and focal linear C3 staining. Antigen-specific serology was consistent with bullous pemphigoid. There was no previously reported cutaneous association of COVID-19 infection with bullous pemphigoid making this case an important addition to the body of evidence helping to identify bullous pemphigoid in the setting of viral infection.

MicroRNAs in pemphigus and pemphigoid diseases

Autoimmune blistering diseases are a heterogenous group of dermatological disorders characterized by blisters and erosions of the skin and/or mucous membranes induced by autoantibodies against structural proteins of the desmosome or the dermal-epidermal adhesion complex including the hemidesmosome. They consist of the two major disease groups, pemphigus and pemphigoid diseases (PPDs). The diagnosis is based on clinical findings, histopathology, direct immunofluorescence, and detection of circulating autoantibodies. The pathogenesis is not fully elucidated, prognostic factors are lacking, and to date, there is no cure for PPDs. MicroRNAs (miRNAs) represent small, non-coding RNAs that play a pivotal role in the posttranscriptional regulation of gene expression. Their dysfunction was highlighted to play a significant role in the pathogenesis of various diseases. Even though a link between miRNAs and autoimmune blistering diseases had been suggested, the research of their involvement in the pathogenesis of PPDs is still in its infancy. miRNAs hold promise for uncovering new layers in the pathogenesis of PPDs, in order to improve diagnosis and also to develop potential therapeutic options. In the current article, we provide an overview regarding current knowledge of miRNAs in terms of complex pathogenesis of PPDs, and, also, their potential role as biomarkers, predictive factors and therapeutic targets.

Detection of autoreactive CD4+ T cells by MHC class II multimers in HLA-linked human autoimmune diseases

Recognition of self-peptides in association with distinct HLA class II alleles by autoreactive CD4+ T cells is central for loss of immunological tolerance leading to autoimmune disease. However, identifying immunodominant self-peptides and characterizing autoreactive T cells is challenging. In this issue of the JCI, Falta et al. identify a disease-associated complementarity-determining region 3β motif specific for beryllium-modified C-C motif ligand 4 (CCL4) and CCL3 self-peptides in patients with chronic beryllium disease (CBD), a granulomatous lung disorder with a known HLA class II allelic association. Detection of these antigen-specific CD4+ T cells by beryllium-pulsed HLA-DP2 tetramers presenting CCL4/CCL3 confirms these autoantigens in humans and mice and enables monitoring in the progress of disease. Detection of autoreactive CD4+ T cells by peptide-MHC class II multimers allows for the detailed characterization of disease-promoting T cells. This knowledge has profound implications for the monitoring and development of targeted therapies in human autoimmune disorders.

Arginase 1+ IL-10+ polymorphonuclear myeloid-derived suppressor cells are elevated in patients with active pemphigus and correlate with an increased Th2/Th1 response

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells, which are characterized by their capability to suppress T-cell responses. While MDSCs have been traditionally associated with cancer diseases, their role as regulators of autoimmune diseases is emerging. Pemphigus is a chronic autoimmune blistering skin disease characterized by dysregulated T-cell responses and autoantibody production. The role of MDSCs in pemphigus disease has not been defined yet. The aim of this study was to characterize MDSCs in pemphigus patients and to dissect their relationship with CD4⁺ T-cell subsets and clinical disease assessments. For this purpose, we performed a cross-sectional analysis of 20 patients with pemphigus. Our results indicate that a population of CD66b⁺ CD11b⁺ polymorphonuclear-like MDSCs (PMN-MDSCs) is expanded in the peripheral blood mononuclear cell fraction of pemphigus patients compared to age-matched healthy donors. These PMN-MDSCs have the capability of suppressing allogeneic T-cell proliferation in vitro and show increased expression of characteristic effector molecules such as arginase I and interleukin-10. We further demonstrate that PMN-MDSCs are especially expanded in patients with active pemphigus, but not in patients in remission. Moreover, MDSC frequencies correlate with an increased Th2/Th1 cell ratio. In conclusion, the identification of a functional PMN-MDSC population suggests a possible role of these cells as regulators of Th cell responses in pemphigus.

Neu aufgetretenes bullöses Pemphigoid bei einer Patientin mit COVID-19

Der vorliegende Artikel berichtet erstmals über ein bullöses pemphigoidartiges Exanthem in Verbindung mit COVID-19. In dieser Arbeit soll ein ungewöhnlicher dermatologischer Fall im Zusammenhang mit einer COVID-19-positiven Infektion vorgestellt werden, um die Virussymptomatik besser zu verstehen. Eine 37-jährige Frau mit Adipositas Grad 3, Diabetes mellitus Typ II und Hypertonie in der Vorgeschichte stellte sich im September 2020 in der Notaufnahme vor und wurde bis November 2020 ambulant und stationär behandelt. Nach Angaben der Patientin lagen bei ihr selbst oder in der Familie keine Hauterkrankungen vor. Die Patientin war vor der stationären Aufnahme positiv auf COVID-19 getestet worden und kam mit einem schweren persistierenden juckenden Exanthem, das die dermatopathologischen, serologischen und klinischen Kriterien für die Diagnose eines bullösen Pemphigoids erfüllte, ins Krankenhaus. Die histopathologische Untersuchung einer HE-gefärbten Stanzbiopsie aus der Beugeseite des linken Handgelenks ergab eine epidermale Keratinozytennekrose, subepidermale Bläschenbildung mit Eosinophilen, zarte Stränge in der papillären Dermis sowie ein subepidermales Ödem. In der direkten Imunfluoreszenz-Stanzbiopsie aus der Beugeseite des linken Handgelenks zeigte sich eine starke lineare IgG-Färbung in der dermoepidermalen Junktionszone mit einer etwas schwächeren fokalen linearen C3-Färbung. Die antigenspezifische Serologie war mit einem bullösen Pemphigoid vereinbar. Bislang liegen keine Berichte über einen Zusammenhang zwischen einer COVID-19-Infektion und einem bullösen Pemphigoid an der Haut vor; daher stellt dieser Fall eine wichtige Ergänzung der Evidenzlage dar und trägt dazu bei, das bullöse Pemphigoid im Zusammenhang mit einer Virusinfektion zu identifizieren.

Kinetic studies of galectin-10 release from eosinophils exposed to proliferating T cells

Galectin-10 is involved in the T cell suppressive activity of regulatory T cells and eosinophils alike. We have identified a subpopulation of T cell suppressive eosinophils that express CD16 on the surface and contain more galectin-10 compared with conventional CD16-negative eosinophils. Our main goal was to determine how the intracellular protein galectin-10 is released from eosinophils when exposed to proliferating T cells and if such release could be inhibited. Confocal microscopy and imaging flow cytometry were used to study the release of galectin-10 from eosinophils incubated with polyclonally activated T cells. T cell proliferation was monitored by measurement of the incorporation of [³ H]-thymidine. Initially, galectin-10-containing synapses formed between eosinophils and T cells. Subsequently, the plasma membrane of eosinophils began to disintegrate and cap-like accumulations of galectin-10 budded on the eosinophil cell surface. Lastly, eosinophil extracellular traps composed of nuclear DNA and galectin-10 were freed. It was solely the CD16-expressing suppressive eosinophils that formed synapses and eosinophil extracellular traps containing galectin-10. Dissolution of the extracellular traps by DNase I partly abrogated the T cell suppression exerted by eosinophils. Extracellular trap formation has mainly been associated with anti-bacterial defense, but we show a new putative function of these cellular formations, as mediators of T cell suppression by enabling the release of galectin-10 from eosinophils.

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.

Autoreactive IgG and IgA B Cells Evolve through Distinct Subclass Switch Pathways in the Autoimmune Disease Pemphigus Vulgaris

Lineage analysis of autoreactive B cells can reveal the origins of autoimmunity. In the autoimmune disease pemphigus vulgaris (PV), desmoglein 3 (DSG3) and DSG1 autoantibodies are predominantly of the IgG4 subclass and less frequently of IgG1 and IgA subclasses, prompting us to investigate whether anti-DSG IgG4 B cells share lineages with IgG1, IgA1, and IgA2. Combining subclass-specific B cell deep sequencing with high-throughput antibody screening, we identified 80 DSG-reactive lineages from 4 PV patients. Most anti-DSG IgG4 B cells lacked clonal relationships to other subclasses and preferentially targeted DSG adhesion domains, whereas anti-DSG IgA frequently evolved from or to other subclasses and recognized a broader range of epitopes. Our findings suggest that anti-DSG IgG4 B cells predominantly evolve independently or diverge early from other subclasses and that IgA is most often not the origin of IgG autoreactivity in PV. These data provide insight into how autoreactivity diversifies across B cell subclasses.

Ellebrecht et al. use next-generation sequencing to identify clonal relationships among antigen-specific B cells in the autoimmune disease pemphigus vulgaris. They find that autoreactive IgG4 B cells are largely clonally distinct from autoreactive IgG1 and IgA, thus elucidating the class-switch pathways that diversify and modify an autoimmune response in humans.

The pathogenesis of bullous skin diseases

Bullous skin diseases are a group of dermatoses characterized by blisters and bullae in the skin and mucous membranes. The etiology and pathogenesis of bullous skin diseases are not completely clear. The most common are pemphigus and bullous pemphigoid (BP). Autoantibodies play critical roles in their pathogenesis. Abnormalities in the adhesion between keratinocytes in patients with pemphigus leads to acantholysis and formation of intra-epidermal blisters. Anti-desmoglein autoantibodies are present both in the circulation and skin lesions of patients with pemphigus. The deficient adhesion of keratinocytes to the basement membrane in BP patients gives rise to subepidermal blisters. Autoantibodies against the components of hemidesmosome can be detected in BP patients. Many novel therapeutics based on knowledge of the pathogenesis have emerged in recent years.

Resolution in bullous pemphigoid

Pemphigoid diseases are a group of autoimmune blistering skin diseases defined by an immune response against certain components of the dermal-epidermal adhesion complex. They are prototypical, autoantibody-driven, organ-specific diseases with the emergence of inflammatory skin lesions dependent on the recruitment of immune cells, particularly granulocytes, into the skin. During an acute flare of disease, inflammatory skin lesions typically progressing from erythema through urticarial plaques to subepidermal blisters erosions erupt and, finally, completely resolve, thus illustrating that resolution of inflammation is continuously executed in pemphigoid disease patients and can be directly monitored on the skin. Despite these superb conditions for examining resolution in pemphigoid diseases as paradigm diseases for antibody-induced tissue inflammation, the mechanisms of resolution in pemphigoid are underinvestigated and still largely elusive. In the last decade, mouse models for pemphigoid diseases were developed, which have been instrumental to identify several key pathways for the initiation of inflammation in these diseases. More recently, also protective pathways, specifically IL-10 and C5aR2 signalling on the molecular level and Tregs on the cellular level, counteracting skin inflammation have been highlighted and may contribute to the continuous execution of resolution in pemphigoid diseases. The upstream orchestrators of this process are currently under investigation. Pemphigoid disease patients, particularly bullous pemphigoid patients, who are predominantly above 75 years of age, often succumb to the side effects of the immunosuppressive therapeutics nowadays still required to suppress the disease. Pemphigoid disease patients may therefore represent a group of patients benefiting most substantially from the introduction of non-immunosuppressive, proresolving therapeutics into the treatment regimens for their disease.

Genetics and Omics Analysis of Autoimmune Skin Blistering Diseases

Autoimmune blistering diseases (AIBDs) of the skin are characterized by autoantibodies against different intra-/extracellular structures within the epidermis and at the basement membrane zone (BMZ). Binding of the antibodies to their target antigen leads to inflammation at the respective binding site and degradation of these structures, resulting in the separation of the affected skin layers. Clinically, blistering, erythema and lesions of the skin and/or mucous membranes can be observed. Based on the localization of the autoantigen, AIBDs can be divided into pemphigus (intra-epidermal blistering diseases) and pemphigoid diseases (sub-epidermal blistering diseases), respectively. Although autoantigens have been extensively characterized, the underlying causes that trigger the diseases are still poorly understood. Besides the environment, genetic factors seem to play an important role in a predisposition to AIBDs. Here, we review currently known genetic and immunological mechanisms that contribute to the pathogenesis of AIBDs. Among the most commonly encountered genetic predispositions for AIBDs are the HLA gene region, and deleterious mutations of key genes for the immune system. Particularly, HLA class II genes such as the HLA-DR and HLA-DQ alleles have been shown to be prevalent in patients. This has prompted further epidemiological studies as well as unbiased Omics approaches on the transcriptome, microbiome, and proteome level to elucidate common and individual genetic risk factors as well as the molecular pathways that lead to the pathogenesis of AIBDs.

Characteristic Pattern of IL-17RA, IL-17RB, and IL-17RC in Monocytes/Macrophages and Mast Cells From Patients With Bullous Pemphigoid

Inflammation is largely implicated in bullous pemphigoid (BP), the most frequent skin auto-immune blistering disease. IL-17, essentially IL-17A/F, has been involved in blister formation through regulation of protease production, and its specific serum profile within BP was related to disease outcome. However, relationships between IL-17 family ligands and receptors are quite complex with six different IL-17 isoforms, and five different receptors. We here aimed at clarifying the contribution of the IL-17 axis in BP by characterizing not only the expression of IL-17 receptor (IL-17R) members within immune cells isolated from BP patients (PMNs, n = 9; T-lymphocytes, n = 10; and monocytes, n = 10) but also the expression of IL-17 isoforms in sera (n = 83), and blister fluid (n = 31) of BP patients. We showed that at diagnosis, IL-17RA and IL-17RC expression were significantly increased in monocytes isolated from BP patients as compared to those from control subjects (p = 0.006 and p = 0.016, respectively). Notably, both IL-17RA and IL-17RC mRNA expression remained elevated in BP monocytes at time of relapse. We further demonstrated a significant increase of all IL-17 isoforms tested in BP blister fluid compared with BP serum (IL-17A, p < 0.0001; IL-17A/F, p < 0.0001; IL-17B, p = 0.0023; IL-17C, p = 0.0022; IL-17E, p < 0.0001). Among all, IL-17B was the only cytokine for which a significant decreased concentration within blister fluid was observed in BP patients with severe disease compared to patients with moderate disease (p = 0.012). We further evidenced a significant negative correlation between IL-17B levels and blister/erosion BPDAI subscore (r = −0.52, p = 0.003). We finally identified mast cells as a potential target of IL-17B in lesional skin of BP patients. In conclusion, we showed here that IL-17RA and IL-17RC expression in monocyte was associated with disease activity and evidenced in situ a negative correlation between BP disease activity and IL-17B, whose effects could be mediated by IL-17RB expressed by mast cell in BP lesional skin.

Pemphigus

Pemphigus consists of a group of rare and severe autoimmune blistering diseases mediated by pathogenic autoantibodies mainly directed against two desmosomal adhesion proteins, desmoglein (Dsg)1 and Dsg3 (also known as DG1 and DG3), which are present in the skin and surface-close mucosae. The binding of autoantibodies to Dsg proteins induces a separation of neighbouring keratinocytes, in a process known as acantholysis. The two main pemphigus variants are pemphigus vulgaris, which often originates with painful oral erosions, and pemphigus foliaceus, which is characterised by exclusive skin lesions. Pemphigus is diagnosed on the basis of either IgG or complement component 3 deposits (or both) at the keratinocyte cell membrane, detected by direct immunofluorescence microscopy of a perilesional biopsy, with serum anti-Dsg1 or anti-Dsg3 antibodies (or both) detected by ELISA. Corticosteroids are the therapeutic mainstay, which have recently been complemented by the anti-CD20 antibody rituximab in moderate and severe disease. Rituximab induces complete remission off therapy in 90% of patients, despite rapid tapering of corticosteroids, thus allowing for a major corticosteroid-sparing effect and a halved number of adverse events related to corticosteroids.

Coagulation and Skin Autoimmunity

Several lines of evidence indicate that the immune system, inflammation, and coagulation are simultaneously activated in autoimmune and immune-mediated skin diseases. Pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-alpha induce the expression of the main initiator of coagulation, i.e., tissue factor. The proteases of coagulation in turn act on protease-activated receptors inducing the expression of various pro-inflammatory cytokines triggering inflammation. The cross-talk among immune system, inflammation, and coagulation amplifies and maintains the activation of all three pathways. This review focuses on three skin disorders as chronic spontaneous urticaria (CSU), angioedema, and bullous pemphigoid (BP), in which the relationships among the three systems have been investigated or their clinical consequences are relevant. Markers of thrombin generation, fibrinolysis, and inflammation have been reported to be increased in the plasma during flares of CSU and angioedema, as well as in the active phase of BP, with the marker levels reverting to normal during remission. The coagulation activation seems to be important only at local level in CSU and angioedema while both at local and systemic levels in BP which is the only condition associated with an increased thrombotic risk. The prothrombotic state in autoimmune skin diseases raises the question of the indication of anticoagulant treatment, particularly in the presence of other cardiovascular risk factors.

Refractory pemphigus foliaceous treated with rituximab

Autoimmune blistering diseases are rare but potentially life-threatening conditions. Pemphigus foliaceus is one of these conditions, characterised by superficial erosions of the skin without mucosal involvement. We report the case of a 57-year-old woman who presented with a 4-week history of rash affecting her scalp with associated hair loss. Clinical and histopathological findings were in keeping with pemphigus foliaceus. She was successfully treated with rituximab, a chimeric monoclonal antibody against CD20, leading to a transient depletion of B cells. After 5 months of follow-up, her rash had cleared, and her hair had completely regrown.

The Role of Eosinophils in Bullous Pemphigoid: A Developing Model of Eosinophil Pathogenicity in Mucocutaneous Disease

Bullous pemphigoid (BP) is an autoimmune blistering disease which carries a significant mortality and morbidity. While historically BP has been characterized as an IgG driven disease mediated by anti-BP180 and BP230 IgG autoantibodies, developments in recent years have further elucidated the role of eosinophils and IgE autoantibodies. In fact, eosinophil infiltration and eosinophilic spongiosis are prominent features in BP. Several observations support a pathogenic role of eosinophils in BP: IL-5, eotaxin, and eosinophil-colony stimulating factor are present in blister fluid; eosinophils line the dermo-epidermal junction (DEJ) in the presence of BP serum, metalloprotease-9 is released by eosinophils at the site of blisters; eosinophil degranulation proteins are found on the affected basement membrane zone as well as in serum corresponding with clinical disease; eosinophil extracellular DNA traps directed against the basement membrane zone are present, IL-5 activated eosinophils cause separation of the DEJ in the presence of BP serum; and eosinophils are the necessary cell required to drive anti-BP180 IgE mediated skin blistering. Still, it is likely that eosinophils contribute to the pathogenesis of BP in numerous other ways that have yet to be explored based on the known biology of eosinophils. We herein will review the role of eosinophils in BP and provide a framework for understanding eosinophil pathogenic mechanisms in mucocutaneous disease.

The Autoimmune Skin Disease Bullous Pemphigoid: The Role of Mast Cells in Autoantibody-Induced Tissue Injury

Bullous pemphigoid (BP) is an autoimmune and inflammatory skin disease associated with subepidermal blistering and autoantibodies directed against the hemidesmosomal components BP180 and BP230. Animal models of BP were developed by passively transferring anti-BP180 IgG into mice, which recapitulates the key features of human BP. By using these in vivo model systems, key cellular and molecular events leading to the BP disease phenotype are identified, including binding of pathogenic IgG to its target, complement activation of the classical pathway, mast cell degranulation, and infiltration and activation of neutrophils. Proteinases released by infiltrating neutrophils cleave BP180 and other hemidesmosome-associated proteins, causing DEJ separation. Mast cells and mast cell-derived mediators including inflammatory cytokines and proteases are increased in lesional skin and blister fluids of BP. BP animal model evidence also implicates mast cells in the pathogenesis of BP. However, recent studies questioned the pathogenic role of mast cells in autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and epidermolysis bullosa acquisita. This review highlights the current knowledge on BP pathophysiology with a focus on a potential role for mast cells in BP and mast cell-related critical issues needing to be addressed in the future.

Incidence of autoimmune bullous diseases in Serbia: a 20-year retrospective study

BACKGROUND AND OBJECTIVES

While most previous surveys on the clinico-epidemiological features of autoimmune bullous diseases (AIBDs) have predominantly focused on a single disease entity or just one disease group, there have been only few studies examining the incidence of various AIBDs. In the present study, we set out to determine the spectrum of AIBDs, to estimate the incidence of the most common AIBDs, and to examine their temporal trends in Central Serbia over a period of 20 years.

METHODS

We retrospectively recruited 1,161 new AIBD cases diagnosed in Central Serbia during the period from January 1991 to December 2010. The diagnosis was based on strict clinical, histological, and immunohistological evaluation.

RESULTS

The incidence rates were: 4.35 per million population/year (pmp/year) for pemphigus, 4.47 pmp/year for pemphigoid, 1.42 pmp/year for dermatitis herpetiformis (DH), 0.25 pmp/year for linear IgA disease, and 0.08 pmp/year for epidermolysis bullosa acquisita. In the period observed, age-adjusted incidence rates significantly increased for pemphigus and particularly for pemphigoid, whereas they decreased, albeit not significantly, for DH.

CONCLUSIONS

For the first time, our study evaluates the incidence rates of the entire spectrum of AIBDs in Serbia, and examines their temporal trends over a 20-year period. To the best of our knowledge, our finding of similar incidence rates for pemphigus and pemphigoid has previously not been reported.

Association of HLA class I and class II alleles with bullous pemphigoid in Chinese Hans

BACKGROUND

Bullous pemphigoid (BP) is one of the most common autoimmune skin diseases. Associations of genes, especially human leukocyte antigen (HLA)-DQ alleles, with BP indicate that genetic predisposition contributes to the disease.

OBJECTIVES

To evaluate the association of HLA class I and HLA class II alleles with susceptibility to BP in the northern Chinese Han population.

METHODS

We performed genotype for HLA-A, -B, -C, -G, -DPA1, -DPB1, -DQA1, -DQB1 and -DRB1 loci in 105 patients with BP by Sanger sequence-based typing (SBT) method. These data were compared with a local control cohort of 420 age- and sex-matched cases.

RESULTS

Among the HLA alleles described herein, the susceptibility alleles associated with a high prevalence of BP were A*11:01 (OR = 1.9 Pc = 0.017); B*37:01 (OR = 8, Pc = 1.811 × 10^-6); G*01:01 (OR = 3.61, Pc = 2.839 × 10^-15) and G*01:06 (OR = 2.22, Pc = 0.025); DQA1*01:05 (OR = 4.87, Pc = 5.822 × 10^-5), DQA1*05:05 (OR = 2.64, Pc = 9.114 × 10^-4), and DQA1*05:08 (OR = 10.2, Pc = 0.016); DQB1*03:01 (OR = 1.69, Pc = 0.048) and DQB1*05:01 (OR = 3.42, Pc = 7.28 × 10^-6); and DRB1*10:01 (OR = 6.85, Pc = 2.63 × 10^-6). To the contrary, HLA-DQA1*01:02 (OR = 0.46, Pc = 8.603 × 10^-4) and DQA1*01:03 (OR = 0.38, Pc = 0.048); DQB1*02:02 (OR = 0.28, Pc = 0.016); and DRB1*07:01 (OR = 0.26, Pc = 0.004) had significant associations with protection against BP. In addition, the frequency of haplotype HLA-DRB1*13-DQA1*05-DQB1*03 (OR = 12.32, Pc = 0.026) in BP patients was significantly higher than those in controls.

CONCLUSION

Our data demonstrated that the alleles and haplotypes found in this study may be important differential genetic markers for susceptibility to or protection against BP in individuals of northern Chinese Han population.

Glucocorticoids: The mode of action in bullous pemphigoid

Bullous pemphigoid (BP) is the most common of pemphigoid diseases caused by autoantibodies against the structures of dermoepidermal junction followed by complement activation, innate immune cell infiltration, neutrophil proteinase secretion and subepidermal blister formation. The first-line treatment of BP is topical and systemic glucocorticoids (GC). Regulation of the immune system and inflammatory cells is the main target of GC actions. GCs act through genomic and non-genomic mechanisms. The human glucocorticoid receptor (GR) mediates most of the biologic effects of GC: cytosolic GR binds GCs and is capable to bind to glucocorticoid response elements in DNA and either transactivate or transrepress genes depending on the tissue and cell type. In addition, GR exerts rapid, non-genomic effects possibly mediated by membrane-localized receptors or by translocation to mitochondria. GCs can also interact directly with several enzymes and cytokines. As a target treatment for BP, the production of autoantibodies should be discontinued. GCs, in spite of their wide immunosuppressive actions, are weak to stop immunoglobulin G (IgG) autoantibody formation. However, both systemic and topical GCs are able to reduce the clinical symptoms of BP. GCs are used to inhibit the secondary inflammation and symptoms, such as blistering and pruritus, and it is shown that GC treatment will gradually decrease also the autoantibody formation. Our review article analyses the mode of action of GC treatment in BP, as far it is possible due to paucity of modern immunological studies.

T regulatory cells and other lymphocyte subsets in patients with bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune blistering disease, and is associated with autoantibodies to the hemidesmosomal BP autoantigens BPAG1 and BPAG2.

AIM

We aimed to investigate the significance of T regulatory cells and other lymphocyte subsets in patients with BP.

METHODS

In total, 31 inpatients with BP were treated with systemic prednisolone in a tapered dose regimen, while 28 healthy individuals matched for age and sex served as the healthy control (HC) group., Blood samples were taken at baseline and after treatment, and levels of inducer/helper and suppressor/cytotoxic T lymphocytes, B lymphocytes, natural killer cells, CD4+CD25++CD127- cells were assessed by flow cytometry, while CD4, CD8, and FOXP3 positivity were assessed by immunohistochemistry, and FOXP3 mRNA was assessed by reverse transcription (RT)-PCR.

RESULTS

Flow cytometry showed that numbers of CD8+ and CD4+CD25++CD127- cells were significantly increased, while the number of CD4+ cells and the CD4/CD8 ratio were significantly decreased at baseline and after therapy in patients with BP compared with HCs. Immunohistology revealed that CD4+, CD8+ and FOXP3+ cells were significantly increased at baseline and post-treatment in patients with BP compared with HCs. FOXP3 mRNA levels were significantly increased in the blood of patients with BP compared with HCs.

CONCLUSION

These results indicate that increased numbers of CD8+, CD4+CD25++CD127- cells and FOXP3+ cells may play a pathogenetic role during the course of BP.

First-line rituximab combined with short-term prednisone versus prednisone alone for the treatment of pemphigus (Ritux 3): a prospective, multicentre, parallel-group, open-label randomised trial

BACKGROUND

High doses of corticosteroids are considered the standard treatment for pemphigus. Because long-term corticosteroid treatment can cause severe and even life-threatening side-effects in patients with this disease, we assessed whether first-line use of rituximab as adjuvant therapy could improve the proportion of patients achieving complete remission off-therapy, compared with corticosteroid treatment alone, while decreasing treatment side-effects of corticosteroids.

METHODS

We did a prospective, multicentre, parallel-group, open-label, randomised trial in 25 dermatology hospital departments in France (Ritux 3). Eligible participants were patients with newly diagnosed pemphigus aged 18-80 years being treated for the first time (not at the time of a relapse). We randomly assigned participants (1:1) to receive either oral prednisone alone, 1·0 or 1·5 mg/kg per day tapered over 12 or 18 months (prednisone alone group), or 1000 mg of intravenous rituximab on days 0 and 14, and 500 mg at months 12 and 18, combined with a short-term prednisone regimen, 0·5 or 1·0 mg/kg per day tapered over 3 or 6 months (rituximab plus short-term prednisone group). Follow-up was for 3 years (study visits were scheduled weekly during the first month of the study, then monthly until month 24, then an additional visit at month 36). Treatment was assigned through central computer-generated randomisation, with stratification according to disease-severity (severe or moderate, based on Harman's criteria). The primary endpoint was the proportion of patients who achieved complete remission off-therapy at month 24 (intention-to-treat analysis). This study is registered with ClinicalTrials.gov, number NCT00784589.

FINDINGS

Between May 10, 2010, and Dec 7, 2012, we enrolled 91 patients and randomly assigned 90 to treatment (90 were analysed; 1 patient withdrew consent before the random assignment). At month 24, 41 (89%) of 46 patients assigned to rituximab plus short-term prednisone were in complete remission off-therapy versus 15 (34%) of 44 assigned to prednisone alone (absolute difference 55 percentage points, 95% CI 38·4-71·7; p<0·0001. This difference corresponded to a relative risk of success of 2·61 (95% CI 1·71-3·99, p<0·0001), corresponding to 1·82 patients (95% CI 1·39-2·60) who would need to be treated with rituximab plus prednisone (rather than prednisone alone) for one additional success. No patient died during the study. More severe adverse events of grade 3-4 were reported in the prednisone-alone group (53 events in 29 patients; mean 1·20 [SD 1·25]) than in the rituximab plus prednisone group (27 events in 16 patients; mean 0·59 [1·15]; p=0·0021). The most common of these events in both groups were diabetes and endocrine disorder (11 [21%] with prednisone alone vs six [22%] with rituximab plus prednisone), myopathy (ten [19%] vs three [11%]), and bone disorders (five [9%] vs five [19%]).

INTERPRETATION

Data from our trial suggest that first-line use of rituximab plus short-term prednisone for patients with pemphigus is more effective than using prednisone alone, with fewer adverse events.

FUNDING

French Ministry of Health, French Society of Dermatology, Roche.

Validation studies of outcome measures in pemphigus

Pemphigus is a group of rare and potentially fatal autoimmune blistering diseases that are associated with auto-antibodies that target intercellular adhesion molecules. Incidence of pemphigus varies among populations, with the lowest incidence in Switzerland and Finland at 0.6–0.76 per million per year and the highest in Jewish communities at 16.1–32 per million per year. Pemphigus is associated with devastating morbidity and despite advancements in our understanding of the disease and a widening array of therapeutic options, no cure exists. The delay in the development of a cure may in part be attributed to the absence of a standardized and completely validated severity outcome measures to allow for high-quality multicenter control studies. Such a tool is necessary to define the best practice in clinical studies, allow for accurate comparisons between study results, justify drug use within the clinical setting, and reduce the cost burden that is associated with the use of ineffective therapies. Utilizing outcome measures that are not validated provides an opportunity to synthesize outcome measures with the intent to favor particular treatments and thus produce false conclusions. According to the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) group, a validation of these measurement instruments requires investigating their responsiveness, reliability, and validity. More than 116 outcome measures exist to assess pemphigus severity, of which the Pemphigus Disease Area Index (PDAI), Autoimmune Bullous Skin Disorder Intensity Score (ABSIS), and Pemphigus Vulgaris Activity Score (PVAS) are the most comprehensively corroborated measures. With regard to validity and reliability, PDAI was unsurpassed by ABSIS and PVAS. Data indicate that ABSIS is more reliable than PVAS, but PVAS seems to have greater validity although the results are not consistent. PDAI, ABSIS, and PVAS have not yet had their responsiveness analyzed, which should be the next step to completely validate the outcome measures and conclusively determine which measure is superior.

The Prevalence of S. aureus Skin and Soft Tissue Infections in Patients with Pemphigus

Pemphigus vulgaris are autoimmune blistering diseases that may result in significant morbidity and death. Immunosuppressive therapy of pemphigus vulgaris would predispose the patients to infections. The aim of this study was to assess the prevalence of S. aureus infection and PVL gene in patients with pemphigus admitted to dermatology clinic. Materials and Methods. This descriptive study was conducted on 196 pemphigus vulgaris patients (119 males, 77 females) admitted to dermatology clinic between 2014 and 2015. In this study, the diagnosis of pemphigus vulgaris was made by histology, immunofluorescence pattern of perilesional skin, and indirect immunofluorescence testing of serum. Data were collected through a questionnaire. Results. 59.1% of pemphigus vulgaris patients had S. aureus infection. 49 out of 116 were methicillin-resistant. PVL gene was detected in 25 out of 116 S. aureus positive patients. Conclusion. This is the first report of S. aureus infection in pemphigus patients in Iran. More than forty percent of isolates were methicillin-resistant S. aureus. PVL gene carried by methicillin-resistant S. aureus was high in this study.