Clinical presentation and diagnostic delay in bullous pemphigoid: a prospective nationwide cohort

The possible and intriguing relationship between bullous pemphigoid and melanoma: speculations on significance and clinical relevance

Bullous pemphigoid (BP) is the most common autoimmune bullous disease: it most commonly affects individuals over 70 years old and impacts severely on their quality of life. BP represents a paradigm for an organ-specific autoimmune disease and is characterized by circulating IgG autoantibodies to hemidesmosomal components: BP180 and BP230. While the crucial role of these autoantibodies in triggering BP inflammatory cascade is fully acknowledged, many ancillary etiological mechanisms need to be elucidated yet. Cutaneous melanoma is due to a malignant transformation of skin melanocytes, that produce and distribute pigments to surrounding keratinocytes. Melanoma is the most fatal skin cancer because of its increasing incidence and its propensity to metastasize. Several data such as: i) reported cases of concomitant melanoma and BP; ii) results from association studies; iii) BP onset following immune check-point inhibitors therapy; iv) expression of BP antigens in transformed melanocytes; and vi) circulating autoantibodies to BP antigens in melanoma patients suggest an intriguing, although unproven, possible association between melanoma and BP. However, a possible causative link is still debated and the putative pathogenetic mechanism underlying this association is unclear. This review aims to describe and discuss the possible relationship between BP and melanoma and give an overview of the speculations for or against this association. Of note, if demonstrated, this association could unwrap considerations of clinical relevance that represent new research frontiers.

Study Design of a Phase 2/3 Randomized Controlled Trial of Dupilumab in Adults with Bullous Pemphigoid: LIBERTY-BP ADEPT

BACKGROUND

Bullous pemphigoid (BP) is a rare, autoimmune, blistering skin disease associated with high disease burden, profoundly decreased quality of life and increased morbidity. Emerging evidence supports an important role for type 2 inflammation in disease pathogenesis. Current management relies on topical and/or systemic corticosteroids, non-selective immunosuppressants and antibiotics with anti-inflammatory properties, which are all limited by side effects and toxicities. Therefore, targeted, efficacious and safe therapies are needed. Dupilumab blocks the shared receptor component for interleukin (IL)-4 and IL-13, key and central drivers of type 2 inflammation. Several reports of patients successfully treated with dupilumab have been published; however, dupilumab has not been formally assessed in a double-blind, placebo-controlled trial.

OBJECTIVES

We report the design of LIBERTY-BP ADEPT, a multicenter, randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of dupilumab in adults with BP.

METHODS

LIBERTY-BP ADEPT comprises a 35-day screening, 52-week treatment and 12-week follow-up period. Approximately 98 adults aged 18-90 years with moderate-to-severe BP are being enrolled at 51 sites on 4 continents and randomized 1:1 to subcutaneous dupilumab or placebo every 2 weeks. All participants will receive concomitant oral corticosteroids (OCS).

PLANNED OUTCOMES

The primary endpoint is the proportion of patients achieving complete remission off steroid therapy at week 36. Key secondary endpoints include total cumulative OCS dose to week 36, percent change and proportion of patients with ≥ 4-point reduction in the weekly average of daily Peak Pruritus Numerical Rating Scale from baseline to week 36 and percent change in Bullous Pemphigoid Area Index score from baseline to week 36.

CONCLUSION

The trial results will provide evidence on whether the efficacy and safety of dupilumab support its use as a potential novel treatment approach for BP and will provide new insights into the role of type 2 inflammation in BP pathogenesis.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04206553.

Prevalence and clinical markers of herpes simplex virus infection in oral lesions of bullous pemphigoid

Background

The manifestations of bullous pemphigoid (BP) and herpes simplex virus (HSV) infection are similar in oral mucosa, and the laboratory detection of HSV has some limitations, making it difficult to identify the HSV infection in oral lesions of BP. In addition, the treatments for BP and HSV infection have contradictory aspects. Thus, it is important to identify the HSV infection in BP patients in time.

Objective

To identify the prevalence and clinical markers of HSV infection in oral lesions of BP.

Methods

This prospective cross-sectional descriptive analytical study was conducted on 42 BP patients with oral lesions. A total of 32 BP patients without oral lesions and 41 healthy individuals were enrolled as control groups. Polymerase chain reaction was used to detect HSV. Clinical and laboratory characteristics of patients with HSV infection were compared with those without infection.

Results

A total of 19 (45.2%) BP patients with oral lesions, none (0.0%) BP patients without oral lesions, and four (9.8%) healthy individuals were positive for HSV on oral mucosa. Among BP patients with oral lesions, the inconsistent activity between oral and skin lesions (p=0.001), absence of blister/blood blister in oral lesions (p=0.020), and pain for oral lesions (p=0.014) were more often seen in HSV-positive than HSV-negative BP patients; the dosage of glucocorticoid (p=0.023) and the accumulated glucocorticoid dosage in the last 2 weeks (2-week AGC dosage) (p=0.018) were higher in HSV-positive BP patients. Combining the above five variables as test variable, the AUC was 0.898 (p<0.001) with HSV infection as state variable in ROC analysis. The absence of blister/blood blister in oral lesions (p=0.030) and pain for oral lesions (p=0.038) were found to be independent predictors of HSV infection in multivariable analysis. A total of 14 (73.7%) HSV-positive BP patients were treated with 2-week famciclovir and the oral mucosa BPDAI scores significantly decreased (p<0.001).

Conclusion

HSV infection is common in BP oral lesions. The inconsistent activity between oral and skin lesions, absence of blister in oral lesions, pain for oral lesions, higher currently used glucocorticoid dosage, and higher 2-week AGC dosage in BP patients should alert physicians to HSV infection in oral lesions and treat them with 2-week famciclovir in time.

Bullous pemphigoid and dipeptidyl peptidase-4 inhibitors: evaluation of clinical course and treatment response

BACKGROUND

Dipeptidyl peptidase-4 inhibitors (DPP4is), drugs used to treat type 2 diabetes mellitus (DM2), show a significant association with bullous pemphigoid (BP) development.

OBJECTIVES

To evaluate the clinical course and development of BP among patients with DM2 treated with DPP4is.

METHODS

This retrospective cohort study included all the patients with BP and comorbid DM2 who visited Sheba Medical Center during 2015-2020.

RESULTS

Among 338 patients with BP, 153 were included in our study. In 92 patients, BP diagnosis was attributed to the use of DPP4is. The patients with DPP4i-associated BP had fewer neurological and cardiovascular comorbidities and higher blistered body surface area (BSA) at first presentation, with noticeable upper and lower limb involvement. These patients were younger and more responsive to treatment, with a greater reduction in their BSA score after 2 months of treatment.

CONCLUSIONS

The clinical features of patients with BP treated with DPP4is were initially more severe; however, during follow-up, a marked clinical improvement was noticed, especially among patients who had ceased the drug. Therefore, although withdrawal of the drug may not impose disease remission, it can alleviate the disease course and avert the need for treatment escalation.

Research progress of omalizumab in the treatment of bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease associated with anti-BP180 and anti-BP230 antibodies. The pathogenic action mechanism of immunoglobulin E (IgE) antibodies in BP has been studied since the 1970s, and IgE antibodies have gradually been confirmed as being important in BP; therefore, anti-IgE therapy may be a new option for the treatment of BP. Omalizumab, as an IgE monoclonal antibody, has been increasingly used clinically to treat BP in recent years. Here, we collected 35 papers investigating omalizumab for BP treatment in a total of 83 patients, and the vast majority of patients showed varying degrees of improvement after treatment, except for a small number of patients with poor clinical outcomes. The patients were then divided into three groups according to dosing frequency and number of doses. Statistical analysis indicated that dosing frequency had little effect on clinical efficacy. While the groups with different numbers of doses were evaluated, the results concluded that clinical efficacy was affected by the number of doses, but there was no positive correlation between the number of doses and clinical efficacy.

Assessment of hydro-saline retention in bullous pemphigoid patients treated with super-potent topical corticosteroids

INTRODUCTION

Super-potent topical corticosteroids (CS) are the mainstay of treatment for bullous pemphigoid. Since super-potent topical CS have systemic effects due to their transcutaneous absorption, we assessed whether super-potent CS were responsible for hydro-saline retention (HSR) in bullous pemphigoid patients.

PATIENTS AND METHODS

From 2015 to 2017, patients with newly-diagnosed bullous pemphigoid treated using clobetasol propionate cream at a starting daily dose of 20 to 40 g were subsequently included in a prospective study. HSR was assessed by longitudinally measuring extracellular water (ECW) volume using bioimpedance analysis (BodyStat QuadScan 4000®) from Day 0 to Day 30 after the initiation of topical CS. Other parameters related to HSR such as weight, blood pressure, natriuresis and proteinuria, were also recorded.

RESULTS

Twenty-nine patients (14 men and 15 women) of mean age 81.8 ± 9.3 years were included and analysed. The mean ECW volume decreased from Day 0 to Day 7 (18.1 ± 4.2 vs 16.7 ± 2.7, p = 0.0094) and was maintained from Day 7 to Day 30 (16.8 ± 2.8 vs 17.0 ± 3.4 L; p = 0.8040). Patient weight loss at Day 30 (69.9 ± 13.6 vs 72.5 ± 14.2 kg, p = 0.0085) was closely correlated with the decrease in ECW volume (r = 0.6740, p < 0.0001). No significant changes in natriuresis, 24-hour proteinuria or blood pressure were observed from Day 0 to Day 30.

CONCLUSION

We found no evidence of HSR in bullous pemphigoid patients treated with super-potent topical CS. Conversely, ECW volume decreased from Day 0 to Day 30, which was correlated with patient weight loss.

Skin Eosinophil Counts in Bullous Pemphigoid as a Prognostic Factor for Disease Severity and Treatment Response

Dermal infiltration of eosinophils and eosinophilic spongiosis are prominent features of bullous pemphigoid lesions. Although several observations support the pathogenic role of eosinophils in bullous pemphigoid, few studies have examined the impact of skin eosinophil counts on disease severity and treatment response. This retrospective study assessed the association between eosinophil counts in skin biopsy samples of 137 patients with bullous pemphigoid and their demographic characteristics, comorbidities, disease severity, and treatment response. There was no relationship between eosinophil count and age, sex, or disease severity at disease onset. There was a positive relationship between eosinophil counts and neurological comorbidity and a negative relationship between eosinophil counts and treatment response. At all follow-up points patients with no tissue eosinophils had a better response to treatment than patients with any tissue eosinophil count. In conclusion, skin eosinophil counts in patients with bullous pemphigoid are not correlated with disease severity at onset, but can serve as a negative prognostic marker for treatment response.

Elevated levels of sCD48 are inversely correlated with markers of disease activity in bullous pemphigoid

sCD48 is elevated in diseases characterized by IgE and eosinophilia. Thus, serum levels sCD48 were evaluated in relation to clinical characteristics of Bullous pemphigoid (BP) patients. sCD48 levels were determined by ELISA in sera from 26 patients with classic BP and 26 healthy controls. Disease severity scores, differential blood counts, and circulating autoantibody levels were obtained. A correlation analysis was performed to establish relationships between sCD48 and clinical and laboratory markers of disease severity. Overall, circulating levels of sCD48 were significantly elevated in BP patients; however, when stratified based on disease severity, patients with mild-moderate disease had higher levels of sCD48 than those with severe disease. A Spearman's correlation analysis identified an inverse relationship between sCD48 and disease activity, serum BP180 IgE and peripheral eosinophil numbers. Further studies are needed to determine the pathologic relevance of these findings.

Type XVII collagen: Relevance of distinct epitopes, complement-independent effects, and association with neurological disorders in pemphigoid disorders

Pemphigoid diseases (PD) are autoimmune skin blistering diseases characterized by autoantibodies directed against proteins of the cutaneous basement membrane zone (BMZ). One of the major antigens is type XVII collagen (BP180), a transmembrane glycoprotein, which is targeted in four PDs: bullous pemphigoid, mucous membrane pemphigoid, linear IgA dermatosis, and pemphigoid gestationis. To date, different epitopes on BP180 have been described to be recognized by PD disease patients’ autoantibodies. Different BP180 epitopes were associated with distinct clinical phenotypes while the underlying mechanisms are not yet fully understood. So far, the main effects of anti-BP180 reactivity are mediated by Fcγ-receptors on immune cells. More precisely, the autoantibody–antigen interaction leads to activation of complement at the BMZ and infiltration of immune cells into the upper dermis and, by the release of specific enzymes and reactive oxygen species, to the degradation of BP180 and other BMZ components, finally manifesting as blisters and erosions. On the other hand, inflammatory responses independent of Fcγ-receptors have also been reported, including the release of proinflammatory cytokines and internalization and depletion of BP180. Autoantibodies against BP180 can also be found in patients with neurological diseases. The assumption that the clinical expression of PD depends on epitope specificity in addition to target antigens, autoantibody isotypes, and antibody glycosylation is supported by the observation that epitopes of PD patients differ from those of PD patients. The aim of the present review is to describe the fine specificities of anti-BP180 autoantibodies in different PDs and highlight the associated clinical differences. Furthermore, the direct effects after binding of the autoantibodies to their target are summarized.

The significance of preclinical anti-BP180 autoantibodies

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease. Although the pathomechanism of BP onset has yet to be elucidated in detail, BP autoantibodies targeting two hemidesmosomal components, BP180 and BP230, are known to play a pivotal role in BP pathogenesis. Thus, the detection and measurement of BP autoantibodies are necessary for diagnosing BP and monitoring the disease activity. Immune assays such as immunofluorescence microscopy, immunoblotting, and ELISAs using BP180 and BP230 detect BP autoantibodies in most BP cases with high specificity; however, BP autoantibodies are sometimes detected in BP patients before the onset of this disease. BP autoantibodies that are detected in patients without typical tense blisters are defined as “preclinical BP autoantibodies”. These preclinical BP autoantibodies are detected even in a low percentage of normal healthy individuals. Although the importance of preclinical BP autoantibodies remains elusive, these autoantibodies might be a potential risk factor for subsequent BP development. Therefore, previous comparative epidemiological studies have focused on the prevalence of preclinical BP autoantibodies in populations susceptible to BP (e.g., the elderly) or in diseases with a higher risk of comorbid BP. This mini-review summarizes the literature on the prevalence of preclinical BP autoantibodies in patients with various conditions and diseases, and we discuss the significance of preclinical BP autoantibody detection.

Updated S2 K guidelines for the management of bullous pemphigoid initiated by the European Academy of Dermatology and Venereology (EADV)

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease of the skin and mucous membranes. This disease typically affects the elderly and presents with itch and localized or, most frequently, generalized bullous lesions. A subset of patients only develops excoriations, prurigo-like lesions, and eczematous and/or urticarial erythematous lesions. The disease, which is significantly associated with neurological disorders, has high morbidity and severely impacts the quality of life.

OBJECTIVES AND METHODOLOGY

The Autoimmune blistering diseases Task Force of the European Academy of Dermatology and Venereology sought to update the guidelines for the management of BP based on new clinical information, and new evidence on diagnostic tools and interventions. The recommendations are either evidence-based or rely on expert opinion. The degree of consent among all task force members was included.

RESULTS

Treatment depends on the severity of BP and patients' comorbidities. High-potency topical corticosteroids are recommended as the mainstay of treatment whenever possible. Oral prednisone at a dose of 0.5 mg/kg/day is a recommended alternative. In case of contraindications or resistance to corticosteroids, immunosuppressive therapies, such as methotrexate, azathioprine, mycophenolate mofetil or mycophenolate acid, may be recommended. The use of doxycycline and dapsone is controversial. They may be recommended, in particular, in patients with contraindications to oral corticosteroids. B-cell-depleting therapy and intravenous immunoglobulins may be considered in treatment-resistant cases. Omalizumab and dupilumab have recently shown promising results. The final version of the guideline was consented to by several patient organizations.

CONCLUSIONS

The guidelines for the management of BP were updated. They summarize evidence- and expert-based recommendations useful in clinical practice.

Histopathology of autoimmune bullous dermatoses: What's new?

Autoimmune bullous dermatoses are characterized by the presence of tissue-bound and often circulating pathogenic autoantibodies targeting structural components of the skin and/or mucous membranes. The diagnostic workup for this heterogeneous group of disorders consists of a multi-step process, of which the light microscopic examination is a crucial component. This review is organized following a classification scheme that is based on two main histopathologic features, namely level of intraepithelial split and composition of the inflammatory infiltrate. Overall, we aim to place emphasis on the histopathologic clues that can assist pathologists in differential diagnosis and review the updates in the literature.

A Review of the Immunologic Pathways Involved in Bullous Pemphigoid and Novel Therapeutic Targets

Bullous pemphigoid (BP) is a rare, chronic antibody-mediated autoimmune blistering disease primarily affecting the elderly, with an age of onset over 60. Current treatment options are limited and involve the use of corticosteroids and immunosuppressants, but their long-term use is associated with significant morbidity and mortality. In Japan, human intravenous immunoglobin is approved for the treatment of corticosteroid-refractory BP. However, no treatment option is approved by the Food and Drug Administration for the management of BP. Therefore, developing effective therapies free of debilitating side effects is imperative. In this review, we summarize the main immunologic pathways involved in the pathogenesis of BP, with an emphasis on the role of eosinophils, immunoglobulins, cytokines such as the interleukin (IL)-4 and IL-5, and complements. We further discuss the latest advances with novel therapeutic targets tested for the management of BP. Ongoing efforts are needed to run well-designed controlled trials and test the efficacy and safety of investigational drugs while providing much-needed access to these medications for refractory patients who will not otherwise be able to afford them as off-label prescriptions.

Strategies to Improve Outcomes of Bullous Pemphigoid: A Comprehensive Review of Clinical Presentations, Diagnosis, and Patients' Assessment

Bullous pemphigoid (BP) is the most frequent autoimmune bullous disease mainly affecting elderlies. Diagnosis usually results from clinical features, histological examination, and the quantification of circulating typical autoantibodies, due to its higher incidence in elderly patients, bullous pemphigoid treatment and management still represents a challenge due to the higher frequency of several comorbidities in this group of patients, which may also be linked to a reduced tolerance to BP treatments. Hence, an early diagnosis and a prompt correct treatment are mandatory to reach better clinical outcomes and improve as much as possible BP outcomes. Herein, we carried out a comprehensive literature review about the known clinical presentations, diagnosis, assessment and monitoring procedures used in daily clinical practice in patients with BP, to better define strategies to improve as much as possible BP clinical outcomes.

Epidemiology and comorbidities in bullous pemphigoid in the period from January of 2019 to the January of 2021

Introduction: Bullous pemphigoid is an autoimmune bullous dermatosis that most commonly occurs in elderly patients. Due to its pathogenesis and treatment of the disease, it can also affect the development of comorbidities. Aim: Determination of comorbidities and their frequency in patients with bullous pemphigoid, as well as their distribution by sex and the estimation of the duration of dermatosis from the onset of symptoms to data collection. Material and methods: In the period from January 2019 to January 2021, a number of 80 patients was analyzed. Basic patient data (age, sex, time of illness) and data on accompanying comorbidities were obtained. Data were categorized based on the ICD-10 classification into groups of diseases, as well as individual diseases that occurred frequently in the population. Results: Of the total number of respondents, 41.3% were male and 58.8% female. The average age of the respondents was 75.8 years, 76.45 years for men and 75.36 years for women. The period from the onset of symptoms to data collection was 3 months, while the average age of the disease in all subjects was 74.4 years. The most common comorbidities were hypertension 73.75%, psychiatric diseases 25%, type 2 diabetes mellitus 25%, other skin diseases 21.25%, urinary tract disorders 18.75%, ischemic heart disease 12.5%, type 1 diabetes mellitus 10%, kidney disease 8.75%, neurological disease 6.25%. Comorbidities were statistically more common in female patients: hypertension, ischemic heart disease, skin diseases and type 2 diabetes mellitus. Conclusion: In our study, bullous pemphigoid is confirmed the disease is of the elderly, predominantly female. Female patients suffer from some comorbidities more often. The period from the onset of symptoms to the collection of data is about 3 months. It is also showed that there are a number of comorbidities in the studied pemphigoid population, however, a large number of studies are needed to determine their association.

Bullous Pemphigoid and Other Pemphigoid Dermatoses

The pemphigoid family of dermatoses is characterized by autoimmune subepidermal blistering. The classic paradigm for pemphigoid, and the most common member, is bullous pemphigoid. Its variable clinical presentation, with or without frank bullae, is linked by significant pruritus afflicting the elderly. Mucous membrane pemphigoid is an umbrella term for a group of subepidermal blistering dermatoses that favor the mucosal membranes and can scar. Epidermolysis bullosa acquisita is a chronic blistering disorder characterized by skin fragility, sensitivity to trauma, and its treatment-refractory nature. Clinicians that encounter these pemphigoid disorders may benefit from an overview of their clinical presentation, diagnostic work-up, and therapeutic management, with an emphasis on the most frequently encountered pemphigoid disease, bullous pemphigoid.

State-of-the-art review of human autoimmune blistering diseases (AIBD)

Autoimmune blistering diseases (AIBDs) are a heterogenous group of skin conditions, broadly classified into two categories depending on the location of blister formation: intraepidermal blistering in the pemphigus group and subepidermal blistering in the pemphigoid group. Although AIBDs occur in both humans and animals, the arsenal of data for human AIBDs far exceeds those of their animal counterpart. Therefore, the main purpose of this review is to highlight existing knowledge, and recent advances in the diagnosis and management of AIBDs in humans - to serve as a road map for veterinary dermatologists. AREAS COVERED: Recent findings include complement-independent pathways in the pathogenesis of bullous pemphigoid, as well as the role of desmoglein and desmocollin autoantibodies in inducing acantholysis. Systemic glucocorticoids are the mainstay of treatment for AIBDs in humans, yet their long-term use is associated with severe adverse effects and complications, thereby limiting their use. Therefore, researchers have been exploring new and safer alternative therapeutic options for human AIBDs such as anti-CD20 monoclonal antibodies (Rituximab), Bruton's tyrosine kinase inhibitors (BTKi) and neonatal Fc receptor (FcRn) blockers. EXPERT OPINION: Randomised controlled trial (RCT) level evidence show that Rituximab and short-course GC regimes are more effective and safer than traditional GC treatment for human AIBDs. FcRn blockers such as SYNT001 have shown positive results in preliminary phase 2 clinical trials for treatment of human pemphigus; further trials are required. Rilzabrutinib (PRN1008), an orally administered BTKi, has recently completed phase 2 trials in pemphigus and is in a phase 3 RCT in humans.

International multicentre observational study to assess the efficacy and safety of a 0·5 mg kg-1 per day starting dose of oral corticosteroids to treat bullous pemphigoid

BACKGROUND

European guidelines propose a 0·5 mg kg^-1 per day dose of oral prednisone as initial treatment for bullous pemphigoid (BP). We assessed the safety and efficacy of this regimen depending on BP extent and general condition of the patients.

METHODS

In a prospective international study, we consecutively included all patients diagnosed with BP. Patients received a 0·5 mg kg^-1 per day dose of prednisone, which was then gradually tapered 15 days after disease control, with the aim of stopping prednisone or maintaining minimal treatment (0·1 mg kg^-1 per day) within 6 months after the start of treatment. The two coprimary endpoints were control of disease activity at day 21 and 1-year overall survival. Disease severity was assessed according to the Bullous Pemphigoid Disease Area Index (BPDAI) score.

RESULTS

In total, 198 patients were included between 2015 and 2017. The final analysis comprised 190 patients with a mean age of 80·9 (SD 9·1) years. Control of disease activity was achieved at day 21 in 119 patients [62·6%, 95% confidence interval (CI) 55·3-69.5]; 18 of 24 patients (75%, 95% CI 53·3-90·2), 75 of 110 patients (68·8%, 95% CI 59·2-77·3) and 26 of 56 patients (46.4%, 95% CI 33·0-60·3) had mild, moderate and severe BP, respectively (P = 0·0218). A total of 30 patients died during the study. The overall Kaplan-Meier 1-year survival was 82·6% (95% CI 76·3-87·4) corresponding to 90·9%, 83·0% and 80·0% rates in patients with mild, moderate and severe BP, respectively (P = 0·5). Thresholds of 49 points for BPDAI score and 70 points for Karnofsky score yielded maximal Youden index values with respect to disease control at day 21 and 1-year survival, respectively.

CONCLUSIONS

A 0·5 mg kg^-1 per day dose of prednisone is a valuable therapeutic option in patients with mild or moderate BP whose general condition allows them to be autonomous.

Immunological features and factors associated with mucocutaneous bullous pemphigoid - a retrospective cohort study

BACKGROUND AND OBJECTIVES

The features of bullous pemphigoid (BP) patients presenting with mucosal lesions are not established. We aimed to elucidate the clinical and immunological features of BP patients with mucosal involvement, and to identify factors associated with mucosal lesions.

PATIENTS AND METHODS

A retrospective study encompassing all consecutive patients diagnosed with BP throughout the years 2009-2019 in a tertiary referral center.

RESULTS

The study encompassed 273 patients with BP, of whom 31 (11.4 %) presented with mucosal lesions. The oral mucosa was the most frequently affected mucosal surface (71.0 %), followed by the genital (25.8 %) and the nasal (22.6 %) mucosae. Relative to other patients with BP, patients with mucosal involvement had a more prominent palmoplantar involvement (67.7 % vs. 37.2 %; P = 0.001); lower seropositivity rate (18.2 % vs. 54.2 %; P = 0.027) and lower levels (29.3 ± 64.5 vs. 129.5 ± 304.4 U/ml; P = 0.016) of anti-BP230 autoantibodies; and decreased peripheral eosinophil counts (760.0 ± 638.6 vs. 1296.3 ± 1013.7; P < 0.001). Absence of anti-BP230 autoantibodies (OR, 5.32; 95 % CI, 1.07-26.32; P = 0.026) and lack of peripheral eosinophilia (OR, 4.31; 95 % CI, 1.14-16.39; P = 0.021) were associated with the presence of mucosal involvement in BP.

CONCLUSIONS

Mucosal involvement is present in a notable subgroup of patients with BP and is associated with the absence of both anti-BP230 antibodies and peripheral eosinophilia.

Bullous Autoimmune Dermatoses–Clinical Features, Diagnostic Evaluation, and Treatment Options

BACKGROUND

Bullous autoimmune dermatoses are a clinically and immunopatho - logically heterogeneous group of diseases, characterized clinically by blisters or erosions of the skin and/or mucous membranes. In Germany, their prevalence is approximately 40 000 cases nationwide, and their incidence approximately 20 new cases per million people per year.

METHODS

This review is based on publications that were retrieved by a selective search of the literature focusing on the current German and European guidelines.

RESULTS

Recent years have seen the publication of guidelines, controlled prospective clinical trials, and multicenter diagnostic studies improving both diagnosis and therapy. Specific monovalent and multivariate serological test systems and pattern analysis of tissue-bound autoantibodies allow identification of the target antigens in 80-90% of patients. This enables the precise classification of disease entities, with implications for treatment selection and disease outcome. In 2019, the anti-CD20 antibody rituximab was approved by the European Medicines Agency for the treatment of moderate and severe pemphigus vulgaris, with an ensuing marked improvement in the care of the affected patients. To treat mild and moderate bullous pemphigoid, topical clobetasol proprionate is recommended, in severe disease, combined with systemic treatment, i.e. usually (a) prednisolone p.o. at an initial dose of 0.5mg/kg/d , (b) an immunomodulant, e.g. dapsone or doxycycline, or (c) prednisolone plus an immunomodulant.

CONCLUSION

The early recognition and precise diagnostic evaluation of bullous autoimmune dermatoses now enables improved, often interdisciplinary treatment, in accordance with the available guidelines. Current research projects are focused on new treatment approaches, an improved understanding of the underlying pathophysiology, and further refinements of diagnostic techniques.

Immunobullous disease

Immunobullous diseases are blistering cutaneous disorders that are caused by pathogenic antibodies binding to protein targets within the skin. There are a range of immunobullous disorders with characteristic morphology that relates to the structural properties of the target protein. In this article we will describe the pathogenesis, clinical features and treatment of the most common immunobullous disorders.

Risk Factors for Mucosal Involvement in Bullous Pemphigoid and the Possible Mechanism: A Review

Bullous pemphigoid (BP) is the most common type of autoimmune bullous disease and is characterized by the presence of circulating anti-BP180 and/or anti-BP230 autoantibodies. Patients with BP often present with tense blisters and erythema, mainly on the trunk and limbs, but a few patients also have mucosal involvement. In this article, we discuss the fact that BP patients with mucosal involvement tend to have more serious conditions and their disease is more difficult to control. Potential risk factors for mucous involvement include earlier age at onset, drugs such as dipeptidyl peptidase-4 inhibitors, cancer, and blood/serum biomarkers, including lower eosinophil count, higher erythrocyte sedimentation rate, IgG autoantibodies against both the NH₂- and COOH-termini of BP180, and the absence of anti-BP230 antibodies. IgA and C3 deposition at the dermo-epidermal junction may also be present. Understanding these risk factors may benefit earlier diagnosis of these patients and promote the development of novel treatments. What's more, it's helpful in deeper understanding of BP development and the relationship between BP and mucous membrane pemphigoid (MMP).

Non-Bullous Pemphigoid: A Single-Center Retrospective Study

INTRODUCTION

Bullous pemphigoid (BP) is an autoimmune disease that typically presents with blisters, but sometimes early lesions may be eczematous, maculopapular, or urticarial. The aim of the present study was to highlight possible differences between typical bullous and non-bullous pemphigoid (NBP) and compare results with the literature. Material &amp; methods: Patients receiving a diagnosis of BP between January 2000 and December 2019 were analyzed. Patients who developed a blister after 3 months from the onset of pruritus were considered as NBP. Demographic features, clinical findings at diagnosis and at 2-year follow-up, histological features, auto-antibodies titers, comorbidities and their treatment were retrieved. Categorical variables were evaluated for normal distribution using a histogram and a Q-Q plot. The χ2 and Fisher's exact tests were used to compare categorical variables between the groups. Continuous variables were compared between the groups using analysis of variance and the independent-samples t test. For multivariate analysis, logistic regression was performed.

RESULTS

A total of 532 patients received a diagnosis of BP. A total of 122 patients were enrolled in the study; 63 were females, and the mean age at the diagnosis was 77.2 years (±11.9 SD). 98 were affected by BP and 24 were categorized as NBP. Mean time to diagnosis was 2.9 months (±5.8 SD) for BP and 30.4 months (±59.8 SD) for NBP (p = 0.0001). Skin manifestations in NBP patients were, in order of frequency: urticarial, papular or nodular, eczematous, and excoriations. Pruritus intensity was high but similar in the two groups (Numerical Rating Scale - NRS, 9.3 vs. 8.9). Seven out of 24 NBP patients (29%) never developed blisters; the other patients developed blisters after a mean follow-up time of 24.9 months (±54.9 SD). NBP patients had a more frequent history of myocardial infarction than BP patients (37.5 vs. 10.2%; p < 0.003). More NBP patients were taking diuretics than BP patients (66.7 vs. 49%; p = 0.03). NBP patients had a worse response to pruritus compared to BP patients at 2 years (NRS 3.7 vs. 11; p 0.001).

CONCLUSIONS

NBP patients have a delayed diagnosis and may be at an increased risk of cardiovascular disease, especially myocardial infarction. Severely and persistently itchy skin disorders in aged patients should be investigated for BP diagnosis.

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.

Factors influencing harmonized health data collection, sharing and linkage in Denmark and Switzerland: A systematic review

INTRODUCTION

The digitalization of medicine has led to a considerable growth of heterogeneous health datasets, which could improve healthcare research if integrated into the clinical life cycle. This process requires, amongst other things, the harmonization of these datasets, which is a prerequisite to improve their quality, re-usability and interoperability. However, there is a wide range of factors that either hinder or favor the harmonized collection, sharing and linkage of health data.

OBJECTIVE

This systematic review aims to identify barriers and facilitators to health data harmonization-including data sharing and linkage-by a comparative analysis of studies from Denmark and Switzerland.

METHODS

Publications from PubMed, Web of Science, EMBASE and CINAHL involving cross-institutional or cross-border collection, sharing or linkage of health data from Denmark or Switzerland were searched to identify the reported barriers and facilitators to data harmonization.

RESULTS

Of the 345 projects included, 240 were single-country and 105 were multinational studies. Regarding national projects, a Swiss study reported on average more barriers and facilitators than a Danish study. Barriers and facilitators of a technical nature were most frequently reported.

CONCLUSION

This systematic review gathered evidence from Denmark and Switzerland on barriers and facilitators concerning data harmonization, sharing and linkage. Barriers and facilitators were strictly interrelated with the national context where projects were carried out. Structural changes, such as legislation implemented at the national level, were mirrored in the projects. This underlines the impact of national strategies in the field of health data. Our findings also suggest that more openness and clarity in the reporting of both barriers and facilitators to data harmonization constitute a key element to promote the successful management of new projects using health data and the implementation of proper policies in this field. Our study findings are thus meaningful beyond these two countries.

Anti-p200 Pemphigoid: A Systematic Review

The many clinical aspects of anti-p200 pemphigoid are not well-characterized. We aimed to analyze and correlate known existing data on the epidemiological, clinical, histological, and immunological features of anti-p200 pemphigoid. We performed a review using Medline, Embase, and Web of Science databases (1900–2018). Case reports and series of patients were included. A total of 68 eligible studies that comprised 113 anti-p200 pemphigoid patients were included in the qualitative analysis, where there was a mean age of onset of 65.5 years. All patients presented with bullae/vesicles, and 54.3% had urticarial plaques. A similarity to bullous pemphigoid was reported in 66.1% of cases, but palmoplantar (51.4%), cephalic (40.3%), and mucosal (38.5%) involvement, besides frequent development of scars/milia (15.7%), were reported. Autoantibodies against recombinant laminin γ1 were detected in the sera of 73.1% of patients. Psoriasis was present in 28.3% of anti-p200 pemphigoid patients, particularly among Japanese patients (56.4%). The incidence of pustular psoriasis in this subgroup, was significantly greater than in the normal population. In conclusion, the diagnosis of anti-p200 pemphigoid may be suspected when a subepidermal autoimmune blistering disease develops in a younger age group, along with significant acral and cephalic distribution and mucosal involvement.

Diagnosis of autoimmune bullous diseases

Autoimmune bullous disorders (AIBDs) are a heterogeneous group of rare diseases clinically characterized by erosions and/or blisters on the skin and mucous membranes. AIBDs can be categorized into two groups: pemphigus diseases, characterized by intraepidermal blistering and autoantibodies against desmosomal proteins such as desmoglein (Dsg) 1, Dsg3, members of the plakin family, and subepidermal AIBDs, comprised of pemphigoid diseases and dermatitis herpetiformis. Autoantibodies in dermatitis herpetiformis target transglutaminases 2 and 3, while in pemphigoid disease, autoantibodies are directed against structural proteins of the dermal-epidermal junction. Although analysis of a perilesional biopsy with direct immunofluorescence (IF) microscopy is still the diagnostic gold standard, several assays have become widely available that allow serological diagnosis in the majority of patients. Standard serological diagnosis includes indirect IF on monkey esophagus and salt-split human skin. Assays to further characterize autoantibody specificity include ELISA systems based on recombinant forms of the immunodominant regions of the target antigens as well as multivariant indirect IF microscopy tests with several miniature substrates. These serological assays are complemented by various in-house assays using immunoblotting and ELISA, which are only available in specialized laboratories. Here we review new developments in the diagnosis of AIBDs and describe state-of-the-art diagnostic procedures for this group of diseases.

Assessment of Diagnostic Strategy for Early Recognition of Bullous and Nonbullous Variants of Pemphigoid

Importance

A substantial number of patients with bullous pemphigoid do not develop skin blisters and may not have received the correct diagnosis. Diagnostic criteria and an optimal diagnostic strategy are needed for early recognition and trials.

Objectives

To assess the minimal requirements for diagnosis of bullous and nonbullous forms of pemphigoid and to evaluate the optimal diagnostic strategy.

Design, Setting, and Participants

This paired, multivariable, diagnostic accuracy study analyzed data from 1125 consecutive patients with suspected pemphigoid who were referred to the Groningen Center for Blistering Diseases from secondary and tertiary care hospitals throughout the Netherlands. Eligible participants were patients with paired data on at least (1) a skin biopsy specimen for the direct immunofluorescence (DIF) microscopy test; (2) indirect immunofluorescence on a human salt-split skin substrate (IIF SSS) test; and (3) 1 or more routine immunoserologic tests administered between January 1, 2002, and May 1, 2015. Samples were taken from patients at the time of first diagnosis, before introduction of immunosuppressive therapy, and within an inclusion window of a maximum of 4 weeks. Data analysis was conducted from October 1, 2015, to December 1, 2017.

Main Outcomes and Measures

Pairwise DIF, IIF SSS, IIF on monkey esophagus, BP180 and BP230 enzyme-linked immunosorbent assays, and immunoblot for BP180 and BP230 tests were performed. The results were reported in accordance with 2015 version of the Standards for Reporting Diagnostic Accuracy.

Results

Of the 1125 patients analyzed, 653 (58.0%) were women and 472 (42.0%) were men, with a mean (SD) age of 63.2 (19.9) years. In total, 343 participants received a pemphigoid diagnosis, with 782 controls. Of the 343 patients, 74 (21.6%, or 1 in 5) presented with nonbullous pemphigoid. The DIF microscopy was the most sensitive diagnostic test (88.3% [n = 303]; 95% CI, 84.5%-91.3%), whereas IIF SSS was less sensitive (77.0% [n = 263]; 95% CI, 72.2%-81.1%) but was highly specific (99.9%; 95% CI, 99.3%-100%) and complemented most cases with negative DIF findings. Results of the BP180 NC16A enzyme-linked immunosorbent assay did not add diagnostic value for initial diagnosis in multivariable logistic regression analysis of combined tests. These findings lead to the proposed minimal criteria for diagnosing pemphigoid: (1) pruritus and/or predominant cutaneous blisters, (2) linear IgG and/or C3c deposits (in an n-serrated pattern) by DIF on a skin biopsy specimen, and (3) positive epidermal side staining of IgG by IIF SSS on a serum sample; this proposal extends bullous pemphigoid with the unrecognized nonbullous form.

Conclusions and Relevance

Both DIF and IIF SSS tests should be performed for diagnosis of the bullous and nonbullous variants of pemphigoid, and the BP180 NC16A enzyme-linked immunosorbent assay is recommended as an add-on test for disease activity monitoring.

Assessment of the Prevalence of Mucosal Involvement in Bullous Pemphigoid

Importance

The prevalence of mucosal involvement in bullous pemphigoid (BP) is inconsistent. Nonoral mucosal involvement was reported anecdotally in few patients with BP.

Objective

To evaluate the prevalence of mucosal involvement in patients with BP, and to characterize the subgroup of patients with mucosal lesions.

Design, Setting, and Participants

A retrospective cohort study was performed including 328 consecutive patients diagnosed with immunopathologically validated BP at a tertiary care referral center for autoimmune bullous diseases in northern Israel between January 1, 2000, and December 31, 2017.

Main Outcome and Measures

The study was conducted to estimate the prevalence and distribution of mucosal involvement among patients with BP. Patients with mucosal involvement were compared with the remaining BP patients regarding clinical and immunological features, laboratory analyses, and treatments.

Results

The study cohort included 139 (42.4%) male and 189 (57.6%) female patients, with a mean (SD) age of 78.0 (11.8) years at presentation. Fifty-six patients (17.1%) presented with mucosal lesions. The oral mucosa was the most frequently affected mucosal surface (n = 44; 13.7%), followed by the laryngeal (n = 16; 4.9%) and the genital (n = 10; 3.0%) mucosae. Among patients with oral lesions, the most involved oral structures were the buccal mucosa (n = 25; 55.6%) and the soft palate (n = 24; 53.3%). Compared with other patients with BP, patients with mucosal involvement were younger (71.8 [14.4] years vs 79.3 [10.8] years; P < .001), presented more frequently with extensive disease (55.4% vs 39.7%; P = .002), had less peripheral eosinophilia (17.8% vs 41.9%; P < .001), and were treated with higher doses of corticosteroids (prednisone >1 mg/kg: 67.9% vs 51.8%; P = .03).

Conclusions and Relevance

Mucosal lesions are present in a notable subgroup of patients with BP and are associated with disease severity. Laryngeal involvement is more common than previously appreciated.

The Intersection of IgE Autoantibodies and Eosinophilia in the Pathogenesis of Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting cellular adhesion molecules. While IgE autoantibodies are occasionally reported in other autoimmune blistering diseases, BP is unique in that most BP patients develop an IgE autoantibody response. It is not known why BP patients develop self-reactive IgE and the precise role of IgE in BP pathogenesis is not fully understood. However, clinical evidence suggests an association between elevated IgE antibodies and eosinophilia in BP patients. Since eosinophils are multipotent effector cells, capable cytotoxicity and immune modulation, the putative interaction between IgE and eosinophils is a primary focus in current studies aimed at understanding the key components of disease pathogenesis. In this review, we provide an overview of BP pathogenesis, highlighting clinical and experimental evidence supporting central roles for IgE and eosinophils as independent mediators of disease and via their interaction. Additionally, therapeutics targeting IgE, the Th2 axis, or eosinophils are also discussed.

Diagnostik blasenbildender Autoimmundermatosen

Blasenbildende Autoimmundermatosen (BAIDs) sind eine heterogene Gruppe seltener Erkrankungen, die klinisch durch Erosionen und/oder Blasen an Haut und Schleimhäuten charakterisiert sind. BAIDs können in zwei Gruppen eingeteilt werden: Pemphigus-Erkrankungen, die durch intraepidermale Blasenbildung und Autoantikörper gegen desmosomale Proteine wie Desmoglein (Dsg) 1, Dsg3 und Mitglieder der Plakin-Familie charakterisiert sind, sowie subepidermale BAIDs, die Pemphigoid-Erkrankungen und die Dermatitis herpetiformis umfassen. Bei der Dermatitis herpetiformis greifen die Autoantikörper die Transglutaminasen 2 und 3 an, während sie bei Pemphigoid-Erkrankungen gegen Strukturproteine der dermoepidermalen Junktionszone gerichtet sind. Die Analyse einer periläsionalen Biopsie mittels direkter Immunfluoreszenzmikroskopie (IF-Mikroskopie) stellt zwar nach wie vor den diagnostischen Goldstandard dar, mittlerweile sind jedoch verschiedene Tests allgemein verfügbar, die eine serologische Diagnosefindung für den Großteil der Patienten ermöglichen. Zur serologischen Standarddiagnostik gehört die indirekte IF auf Affenösophagus und NaCl-separierter Spalthaut. Die Spezifität der Autoantikörper kann mit ELISA-Systemen, die auf rekombinanten Formen der immundominanten Regionen der Zielantigene basieren, sowie indirekter IF-Mikroskopie anhand multivarianter Tests mit mehreren multivariate näher charakterisiert werden. Diese serologischen Tests werden durch verschiedene hauseigene Immunoblotting- und ELISA-Systeme ergänzt, die nur in spezialisierten Laboratorien verfügbar sind. In diesem Review geben wir einen Überblick über neue Entwicklungen bei der Diagnose von BAIDs und beschreiben moderne Diagnoseverfahren für diese Krankheitsgruppe.

Nonbullous pemphigoid: Insights in clinical and diagnostic findings, treatment responses, and prognosis

BACKGROUND

Nonbullous pemphigoid is an under-recognized phenotype of the autoimmune bullous disease pemphigoid, characterized by the absence of blisters. Several disease aspects have not been studied previously.

OBJECTIVE

To describe the characteristics of nonbullous pemphigoid.

METHODS

A retrospective review study of medical records. The diagnosis of pemphigoid was based on meeting 2 of the following 3 criteria: (1) pruritus, (2) positive direct immunofluorescence microscopy, or (3) positive indirect immunofluorescence microscopy on salt-split skin.

RESULTS

The review included 69 patients. The mean delay in diagnosis was 29 months. Skin examination most often showed pruritic papules/nodules (37%) or pruritus without primary skin lesions (22%). Histopathologic findings were mainly nonspecific. Results of direct and indirect immunofluorescence microscopy were positive in 60% and 69%, respectively. During follow-up, blisters formed in 17%, which was associated with a positive indirect immunofluorescence microscopy (P = .014) and a positive BP180 immunoblot result (P = .032). The Kaplan-Meier estimates of mortality at 1, 2, and 3 years were 14%, 34%, and 46%, respectively, with an 8.6-fold increased all-cause mortality risk.

LIMITATIONS

The retrospective study design.

CONCLUSIONS

Nonbullous pemphigoid presented with heterogeneous pruritic skin lesions, resulting in delayed diagnosis. Direct and indirect immunofluorescence microscopy are essential to diagnose nonbullous pemphigoid, in contrast to histopathology, mainly showing nonspecific findings. An increased all-cause mortality risk was observed during follow-up.

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.

Dipeptidyl Peptidase-4 Inhibitor-Associated Bullous Pemphigoid

Bullous pemphigoid (BP) is an organ-specific autoantibody-mediated blistering skin disease that mainly affects the elderly. Typical clinical features include the widespread blisters, often preceded by and/or associated with itchy urticarial or eczema-like lesions. BP patients have circulating autoantibodies against BP180 and/or the plakin family protein BP230 both of which are components of hemidesmosomes in basal keratinocytes. Most BP autoantibodies particularly target the epitopes within the non-collagenous NC16A domain of BP180. Clinical findings and murine models of BP have provided evidence of a pathogenic role of anti-NC16A autoantibodies. However, it is largely unknown what triggers the breakage of immunotolerance against BP180 in elderly individuals. The incidence of BP has been increased over the past two decades in several countries. Aside from aging populations, the factors behind this phenomenon are still not fully understood. Neurodegenerative diseases such as multiple sclerosis, Parkinson's disease, and certain dementias are independent risk factors for BP. Recently several case reports have described BP in patients with diabetes mellitus (DM) patients who have been treated with dipeptidyl peptidase-4 inhibitors (DPP-4i or gliptins), which are a widely used class of anti-DM drugs. The association between the use of DPP-4is, particularly vildagliptin, and BP risk has been confirmed by several epidemiological studies. Evidence suggests that cases of gliptin-associated BP in Japan display certain features that set them apart from cases of “regular” BP. These include a “non-inflammatory” phenotype, targeting by antibodies of different immunodominant BP180 epitopes, and a specific association with the human leukocyte antigen (HLA) types. However, recent studies in European populations have found no major differences between the clinical and immunological characteristics of gliptin-associated BP and “regular” BP. The DPP-4 protein (also known as CD26) is ubiquitously expressed and has multiple functions in various cell types. The different effects of the inhibition of DPP-4/CD26 activity include, for example, tissue modeling and regulation of inflammatory cells such as T lymphocytes. Although the pathomechanism of gliptin-associated BP is currently largely unknown, investigation of the unique effect of gliptins in the induction of BP may provide a novel route to better understanding of how immunotolerance against BP180 breaks down in BP.

Subepidermal autoimmune bullous diseases: overview, epidemiology, and associations

Subepidermal autoimmune bullous diseases of the skin and mucosae comprise a large group of chronic diseases, including bullous pemphigoid, pemphigoid gestationis, mucous membrane pemphigoid, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. These diseases are characterized by an antibody response toward structural components of the basement membrane zone, resulting in subepidermal blistering. The epidemiological features of these diseases vary substantially in different regions of the world. Observational studies investigating comorbidities and associations among patients with these diseases are inconsistent and sometimes inconclusive. This review provides a brief overview regarding each one of the subepidermal autoimmune bullous diseases. In addition, it summarizes the most recent understanding of the epidemiological features and associations of this group of organ-specific autoimmune diseases.

Diagnosis of Autoimmune Blistering Diseases

Autoimmune skin blistering diseases (AIBD) are characterized by autoantibodies that are directed against structural proteins in the skin and adjacent mucous membranes. Some clinical signs are typical for a specific AIBD, however, correct diagnosis requires the detection of tissue-bound or circulating autoantibodies. The gold standard for diagnosis of AIBD is the detection of autoantibodies or complement component 3 by direct immunofluorescence (DIF) microscopy of a perilesional biopsy. Circulating antibodies can be detected via indirect immunofluorescence (IIF) microscopy of different tissue substrates including human skin, monkey esophagus, and more recently, recombinant forms of the different target antigens. Latter are also employed in various commercial ELISA systems and by immunoblotting in in-house assays available in specialized laboratories. ELISA systems are also particularly valuable for monitoring of the disease activity during the disease course which can be helpful for treatment decisions. Exact diagnosis is essential for both treatment and prognosis, since some AIBD are associated with malign tumors such as paraneoplastic pemphigus and anti-laminin 332 mucous membrane pemphigoid. This review presents clinical and immunopathological features of AIBD for the state-of the art diagnosis of these disorders.

The spectrum of histopathologic findings in pemphigoid: Avoiding diagnostic pitfalls

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune vesiculobullous dermatitis that primarily affects the elderly and presents with tense, fluid-filled blisters. The histological hallmark on routine hematoxylin & eosin (H&E)-stained specimens is a subepidermal blister with luminal eosinophils. However, there are histologic variants than can produce diagnostic confusion.

METHODS

All immunofluorescence reports from an independent certified dermatopathology laboratory (2006-2015) were inspected, and those with findings consistent with an autoimmune subepidermal blistering process were selected. Seventy-seven cases were identified, and the corresponding H&E-stained specimens were reviewed by two dermatopathologists who tabulated the histopathologic findings.

RESULTS

Just over half of biopsies showed subepidermal clefting (54%). The histologic variants included: urticarial or eczematous findings (17%), partial or complete re-epithelialization (28%), and epidermal necrosis (7%).

CONCLUSION

While re-epithelialization of subepidermal blisters is a commonly accepted phenomenon, there are no published data demonstrating its incidence. Because only half of the biopsies showed the classic subepidermal blister, it is important to be aware of the spectrum of histopathologic findings that occur in this disease. Specifically, the presence of an intraepidermal blister and/or epidermal necrosis on routine H&E-stained specimens does not preclude the diagnosis of pemphigoid.

Autoimmune Subepidermal Bullous Diseases of the Skin and Mucosae: Clinical Features, Diagnosis, and Management

Autoimmune subepidermal blistering diseases of the skin and mucosae constitute a large group of sometimes devastating diseases, encompassing bullous pemphigoid, gestational pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, and anti-p200 pemphigoid. Their clinical presentation is polymorphic. These autoimmune blistering diseases are associated with autoantibodies that target distinct components of the basement membrane zone of stratified epithelia. These autoantigens represent structural proteins important for maintenance of dermo-epidermal integrity. Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease of the skin and mucosae. Although the disease typically presents with a generalized blistering eruption associated with itch, atypical variants with either localized bullous lesions or "non-bullous" presentations are observed in approximately 20% of patients. A peculiar form of BP typically associated with pregnancy is pemphigoid gestationis. In anti-p200 pemphigoid, patients present with tense blisters on erythematosus or normal skin resembling BP, with a predilection for acral surfaces. These patients have antibodies targeting the 200-kDa basement membrane protein. Epidermolysis bullosa is a rare autoimmune blistering disease associated with autoantibodies against type VII collagen that can have several phenotypes including a classical form mimicking dystrophic epidermolysis bullosa, an inflammatory presentation mimicking BP, or mucous membrane pemphigoid-like lesions. Mucous membrane pemphigoid (MMP) is the term agreed upon by international consensus for an autoimmune blistering disorder, which affects one or more mucous membrane and may involve the skin. The condition involves a number of different autoantigens in the basement membrane zone. It may result in severe complications from scarring, such as blindness and strictures. Diagnosis of these diseases relies on direct immunofluorescence microscopy studies and immunoserological assays. Management of affected patients is often challenging. We will here review the clinical and immunopathological features as well as the pathophysiology of this group of organ-specific autoimmune diseases. Finally, we will discuss the diagnostic approach and the principles of management in clinical practice.

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.

Peripheral eosinophilia in bullous pemphigoid: prevalence and influence on the clinical manifestation

BACKGROUND

Peripheral eosinophilia has been reported in 50-60% of patients with bullous pemphigoid (BP) and correlated positively with disease severity.

OBJECTIVES

To establish an association of peripheral eosinophilia with the different morphological characteristics of BP.

METHODS

The study was designed as a case-control study. Diagnosis of BP was grounded on well-established immunopathological criteria. Five age-, sex- and ethnicity-matched controls were randomly selected for each patient with BP.

RESULTS

Overall, 225 patients with BP and 1125 control participants were enrolled. A total of 113 (50·2%) patients with BP and 49 (4·4%) controls had pathological peripheral eosinophilia (P < 0·001). An independent association between eosinophil count and the diagnosis of BP was observed [odds ratio 59·9 (per 1000 eosinophil μL^-1 increase); P < 0·001]. Patients with BP with eosinophilia were significantly older at presentation (P = 0·003) and had increased palmoplantar involvement (P = 0·005), whereas patients with normal eosinophil counts had greater involvement of mucosal surfaces (P = 0·002) and the head and neck (P = 0·047). Patients with BP with extensive disease had significantly higher eosinophil counts than patients with mild-to-moderate disease (996·5 ± 1052·5 vs. 696·1 ± 962·6 cells μL^-1 ; P < 0·001).

CONCLUSIONS

Patients with BP with serum eosinophilia were significantly older and had higher palmoplantar involvement. Patients with BP with a normal eosinophil count were younger and presented more frequently with atypical clinical manifestations.

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.

Direct Immunofluorescence Using Non-Lesional Buccal Mucosa in Mucous Membrane Pemphigoid

Mucous membrane pemphigoid (MMP) is a rare organ-specific autoimmune subepithelial blistering disease with predominantly mucosal erosions, most frequently affecting the gingiva. Erosions in the oral cavity usually result in markedly decreased quality of life. The major autoantigens are BP180 and laminin332, which are components of basement membrane proteins in the skin and mucosa. Diagnosis is usually difficult due to histological destruction of the tissue and low autoantibody titers. In this study, we evaluated the diagnostic value of direct immunofluorescence (DIF) using non-lesional buccal mucosa in seven cases of MMP. In all seven patients, gingival lesions were clinically observed, and in one of the seven patients, buccal lesions were also clinically observed. First, we performed DIF to detect tissue-bound autoantibodies and complement. DIF from non-lesional buccal mucosa revealed linear deposits of IgG and C3 at the basement membrane zone in all cases. To detect autoantibodies, indirect immunofluorescence (IIF), BP180-NC16A ELISA and immunoblotting were performed. Surprisingly, circulating autoantibodies were unable to be detected in any of the cases by ELISA, IIF, or immunoblotting. Furthermore, histological separation was observed in one patient. In conclusion, DIF using non-lesional buccal mucosa was found to be superior to histological and serological tests for diagnosing mucous membrane pemphigoid. The procedure is technically easy and has high diagnostic value.