Serration pattern analysis for differentiating epidermolysis bullosa acquisita from other pemphigoid diseases

Direct immunofluorescence demystified: Essential insights and recent advances for dermatologists

Direct immunofluorescence (DIF) is widely used in dermatopathology for the diagnosis of autoimmune blistering diseases (AIBDs), cutaneous vasculitis, and connective tissue disorders. Although it is easy and useful to perform, it needs technical expertise and experience for proper interpretation. The yield of DIF depends on multiple factors including the adequacy, transportation, storage, processing, and interpretation of the biopsy specimen. Effective collaboration between the dermatologist and dermatopathologist along with meticulous clinico-pathological correlation is crucial for accurately interpreting DIF in the appropriate clinical context. In this narrative review of DIF in dermatology, we discuss the indications of DIF, recent updates on the selection of optimum biopsy sites, basic techniques of DIF including the classical transport medium and its alternatives, processing and staining technique, patterns in various diseases, advancements such as serration pattern analysis, and latest recommendations on the use of DIF in cutaneous disorders.

Artificial intelligence in autoimmune bullous dermatoses

Dermatologists treating patients with autoimmune bullous dermatoses (AIBDs), as well as the patients themselves, encounter challenges at every stage of their interaction, including dermatologic and comorbidities assessment, diagnosis, prognosis evaluation, treatment, and follow-up monitoring. We summarize the current and potential future clinical applications of artificial intelligence (AI) in the field of AIBDs. Recent research and AI models have demonstrated their potential to enhance or may already be contributing to advancements in every phase of the comprehensive diagnosis and personalized treatment process in AIBDs, providing patients, clinicians, and administrators with valuable support. Image recognition AI systems might assist precise clinical diagnoses of various diseases, including AIBDs, and could offer consistent and reliable scoring of disease severity. Automated and standardized AI-assisted laboratory methods could improve the accuracy and decrease the time and cost of gold-standard tests such as direct and indirect immunofluorescence. The studies and tools discussed in this contribution, although in the early stages, might be a small precursor to a transformative shift in the way we take care of patients with chronic skin diseases, including AIBDs.

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

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

Accuracy of serration pattern analysis by direct immunofluorescence in subepidermal autoimmune blistering diseases

Background Direct immunofluorescence (DIF) is essential for the diagnosis of sub-epidermal immunobullous diseases (SIBD). Bullous pemphigoid (BP), a sub-epidermal immunobullous disease, shows linear IgG and C3 deposition along the dermo-epidermal junction by DIF. However, similar histological and DIF findings are also seen in epidermolysis bullosa acquisita (EBA). High-power examination of antibody deposition by DIF in a "u" or "n" serrated pattern can help differentiate these two entities. Aims/Objectives The aim of this study was to determine the diagnostic accuracy of serration patterns in IgG-mediated sub-epidermal immunobullous disease. Methods All cases of IgG-mediated sub-epidermal immunobullous disease diagnosed over the past 2 years and 9 months period and confirmed serologically, were included. Examination of the serration pattern in DIF was assessed on oil emersion. Salt split skin indirect immunofluorescence (SSS IIF), BP180 enzyme-linked immunosorbent assay (ELISA), profile ELISA and BIOCHIP mosaic were performed, wherever available. Results This study included 74 cases of bullous pemphigoid, eight cases of mucus membrane pemphigoid (MMP) and one case of epidermolysis bullosa acquisita. The characteristic zigzag "n" pattern was visualised in 66 out of 82 cases (80.5%) of the pemphigoid group (BP + MMP); the single epidermolysis bullosa acquisita case showed the "u" serrated pattern. No statistical correlation was seen between serration pattern and BP180 positivity by ELISA (P = 0.05). Limitations The study is limited by the single case of epidermolysis bullosa acquisita (which could be due to rarity of this disease in north Indian population due to genetic variation), lack of detailed serological investigations and immunoblot in all cases. Conclusion Serration pattern analysis is an easy-to-interpret and highly useful technique for characterisation of sub-epidermal immunobullous diseases.

Successful pharmacological intervention at different levels of the complement system in an in vitro complement fixation model for bullous pemphigoid

Bullous pemphigoid (BP) is characterized by deposition of immunoglobulins and complement along the epidermal basement membrane (BM). In humans, there is a lack of functional studies targeting the complement system (CS). This study investigates activation of all complement pathways in BP skin biopsies. Moreover, pharmacological inhibition at different levels of the CS was investigated using anti-complement compounds in a complement fixation BP assay. In this retrospective study, 21 frozen biopsies from BP patients were stained by direct immunofluorescence for C1q, MBL, ficolin-2, C4d, properdin, C3c and C5b-9. Sera from 10 patients were analysed in a complement fixation assay in the presence of C1 inhibitor, anti-factor B monoclonal antibody (mAb), anti-C3 mAb and anti-C5 mAb and compared with dexamethasone. The two readouts were the quantity of complement deposited along the BM and the release of sC5b-9 in the supernatant. Our results show classical and alternative complement pathway activation in BP skin biopsies, but could not demonstrate significant lectin pathway activation. In contrast to dexamethasone, complement deposition along the BM could be selectively inhibited by anti-C1 and anti- factor B. More downstream, selective intervention at the level of C3 and C5 could effectively reduce complement deposition along the BM and the release of sC5b-9 in the supernatant. This study shows that selective intervention in either the classical, alternative or terminal pathway prevented deposition of complement along the BM in an in vitro BP model. The results of our study greatly encourage the clinical development of complement inhibitors for the treatment of BP.

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

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

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.

Coexistence of Anti-p200 Pemphigoid and Psoriasis: A Systematic Review

Background

A close association between psoriasis and anti-p200 pemphigoid has been demonstrated by numerous studies. However, the clinical characteristics of patients suffering from these two entities have not yet been well-elucidated.

Objective

This study aimed to review the case reports and case series, summarizing clinical features and therapeutic strategies in patients suffering from anti-p200 pemphigoid and psoriasis.

Methods

A systematic review was conducted by searching PubMed, EMBASE, and Web of Science databases for studies published in English involving patients with psoriasis and anti-p200 pemphigoid on 6 September 2021. All case reports and case series reporting patients diagnosed with anti-p200 pemphigoid and psoriasis were included in this systematic review.

Results

A total of 21 eligible studies comprising 26 anti-p200 pemphigoid patients with preceding psoriasis were included in the qualitative synthesis. The average age at blisters eruption was 62.5 years, and the mean duration between the two entities was 15.6 years. Twenty-four percent of patients developed bullous lesions during UV therapy. Clinical manifestation of bullae and/or vesicles was recorded in all patients, and the trunk (94.7%) was most frequently involved, with only 15.8% reporting mucosal involvement. Epitope spreading was detected by immunoblotting in 33.3% of patients. All the patients reached completed remission during the course of disease, with 36.8% experiencing at least one relapse. Monotherapy of prednisolone was the leading therapeutic approach (n=6, 31.6%) required for disease control, but 5 (83.3%) of them suffered from blister recurrence after tapering or ceasing corticosteroid.

Conclusion

Most of the clinical aspects of patients with anti-p200 pemphigoid and psoriasis were similar to what was demonstrated in previous articles on anti-p200 pemphigoid. Nevertheless, compared with other anti-p200 pemphigoid cases without psoriasis, a clinical manifestation pattern with more frequent involvement of the trunk and less mucosal involvement was illustrated in those with psoriasis. Generally, monotherapy is sufficient for a complete remission for such patients. However, one or more relapses have been recorded in a considerable portion of patients, especially those prescribed with prednisolone. It reminded us to be more cautious during a tapering of medication.

Diagnostics for Dermatologic Diseases with Autoantibodies

Background

Dermatologic diseases with autoantibodies were recognized early as autoimmunity became accepted as a pathogenic immunologic concept. Laboratory testing to identify disease-defining autoantibodies and investigate their role in pathophysiology has evolved since.

Content

Blistering dermatologic diseases, profiled by autoantibody production, target epithelial components critical in cell–cell and cell–matrix adhesion, resulting in epithelial separation and other characteristic features of the disorders. This review covers the clinical indications for dermatologic disease-related autoantibody testing, the specifics of procuring specimens to test, the available diagnostic tests, and information provided by the testing. Atypical, uncharacteristic, and less well-known clinical and autoantibody profiles as well as several of the many future prospects for expansion of the testing applications are elaborated on in the online Data Supplement.

Summary

Autoantibody-associated dermatologic diseases are acquired immunologic disorders that have considerable clinical implications affecting essential barrier functions of skin and mucous membranes and causing discomfort, including pain and pruritus. Certain of the diseases can have life-threatening manifestations, and treatments can have significant side-effects. The skin diseases may presage other clinical associations that are important to recognize and treat. Laboratory testing aids in the diagnosis of these diseases through identification of the autoantibodies and is essential for prompt and precise knowledge of the disease type for prognosis, further clinical evaluations, and treatment decisions.

Diagnostic Utility of C4d by Direct Immunofluorescence in Bullous Pemphigoid

ABSTRACT

Bullous pemphigoid (BP) is an autoimmune blistering disease that commonly affects elderly patients. Direct immunofluorescence (DIF) for immunoglobulin G (IgG) and C3c on frozen skin biopsies is the gold standard for the diagnosis of BP. In a minority of cases, IgG and/or C3c are found negative, and in these situations, there is a need for a more stable diagnostic marker of BP. C4d is biologically inactive, but has a long half-life, rendering it a long-lived marker for antibody-mediated complement activation. Previous studies already demonstrated that C4d was diagnostically useful in formalin-fixed paraffin-embedded skin biopsies of patients with BP. We hypothesized that C4d detected by DIF could also be a promising diagnostic marker for BP, particularly in IgG and/or C3c DIF-negative cases. In this single-center retrospective study, 69 cases of BP were analyzed for linear deposition of C4d; of the 69 cases, n = 26 were IgG+/C3c-, n = 10 IgG+/C3c+, and n = 33 IgG-/C3c-. Results were compared with n = 39 negative controls. Seven of the 26 (27%) IgG+/C3c- and 3 of the 33 (9%) IgG-/C3c- BP cases were positive for C4d. All 10 IgG+/C3c+ cases were also C4d positive. In the negative control group, 2 of the 39 (5%) were found positive for C4d. In conclusion, the current study shows that C4d is a more sensitive but not a 100% specific marker of BP. We conclude that C4d by DIF could be an interesting diagnostic adjunct for BP, particularly in IgG-/C3c- double negative cases.

European Guidelines (S3) on diagnosis and management of mucous membrane pemphigoid, initiated by the European Academy of Dermatology and Venereology - Part II

This guideline has been initiated by the task force Autoimmune Blistering Diseases of the European Academy of Dermatology and Venereology, including physicians from all relevant disciplines and patient organizations. It is a S3 consensus-based guideline that systematically reviewed the literature on mucous membrane pemphigoid (MMP) in the MEDLINE and EMBASE databases until June 2019, with no limitations on language. While the first part of this guideline addressed methodology, as well as epidemiology, terminology, aetiology, clinical presentation and outcome measures in MMP, the second part presents the diagnostics and management of MMP. MMP should be suspected in cases with predominant mucosal lesions. Direct immunofluorescence microscopy to detect tissue-bound IgG, IgA and/or complement C3, combined with serological testing for circulating autoantibodies are recommended. In most patients, serum autoantibodies are present only in low levels and in variable proportions, depending on the clinical sites involved. Circulating autoantibodies are determined by indirect IF assays using tissue substrates, or ELISA using different recombinant forms of the target antigens or immunoblotting using different substrates. The major target antigen in MMP is type XVII collagen (BP180), although in 10-25% of patients laminin 332 is recognized. In 25-30% of MMP patients with anti-laminin 332 reactivity, malignancies have been associated. As first-line treatment of mild/moderate MMP, dapsone, methotrexate or tetracyclines and/or topical corticosteroids are recommended. For severe MMP, dapsone and oral or intravenous cyclophosphamide and/or oral corticosteroids are recommended as first-line regimens. Additional recommendations are given, tailored to treatment of single-site MMP such as oral, ocular, laryngeal, oesophageal and genital MMP, as well as the diagnosis of ocular MMP. Treatment recommendations are limited by the complete lack of high-quality randomized controlled trials.

Serration pattern analysis as a practical adjunct tool for categorization of subepidermal autoimmune blistering diseases

BACKGROUND

Serration pattern analysis helps in the classification of subepidermal autoimmune blistering disorders; more precisely, it helps to differentiate epidermolysis bullosa acquisita from other subepidermal autoimmune blistering disorders. Most of the published reports of this tool have come from a single center.

OBJECTIVES

The objectives of the study were to study the utility of serration pattern analysis in classifying subepidermal autoimmune blistering disorders.

METHODS

Seventy five cases of subepidermal autoimmune blistering disorders were enrolled in this prospective study. A three millimeter punch biopsy was taken from the perilesional skin or mucosa for direct immunofluorescence; indirect immunofluorescence was carried out using salt-split skin. Subclassification of subepidermal autoimmune blistering disorders was done based on direct immunofluorescence, indirect immunofluorescence on salt-split skin, indirect immunofluorescence using knockout skin and serration pattern analysis findings.

RESULTS

Indirect immunofluorescence was positive in 68 cases; 14 cases showed a dermal staining pattern while the rest showed either an epidermal or a combined pattern. All patients with epidermal or combined staining patterns showed "n" serrated pattern on direct immunofluorescence. Nine patients with dermal staining on indirect immunofluorescence also revealed an "n" serration pattern on direct immunofluorescence indicating the diagnosis of anti-p200 pemphigoid, and the rest showed a "u" serrated pattern. Three patients with negative indirect immunofluorescence showed "u" serration on direct immunofluorescence while the rest showed "n" serration.

LIMITATIONS

ELISA and immunoblotting could not be performed due to resource constraints.

CONCLUSION

Based on indirect immunofluorescence and serration pattern analysis, classification of the majority of patients with subepidermal autoimmune blistering disorders was possible in our study. Pattern recognition is a cost-effective tool and can be easily learnt. It is recommended to be practiced in all laboratories where facilities for advanced immunological diagnosis are unavailable.

Bullous Autoimmune Dermatoses

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.

Evaluation and Comparison of Clinical and iLaboratory Characteristics of Patients With IgA Epidermolysis Bullosa Acquisita, Linear IgA Bullous Dermatosis, and IgG Epidermolysis Bullosa Acquisita

Importance

Immunoglobulin A (IgA) epidermolysis bullosa acquisita (EBA) is an autoimmune skin blistering disease with IgA autoantibodies directed against type VII collagen. There is debate whether it should be considered part of the clinical spectrum of linear IgA bullous dermatosis (LABD) or a separate disease entity.

Objective

This cohort study aimed to define the clinical features and treatment responses of IgA EBA and anti-BP180-driven LABD, and to compare the prevalences of IgA EBA anti-BP180 LABD and classic IgG-mediated EBA in an autoimmune diagnostic laboratory database.

Design, Setting, and Participants

This retrospective cohort study and case series study included demographic, immunopathologic, and serologic data from 300 patients diagnosed with IgA EBA, IgG EBA, or LABD. Furthermore, clinical features and treatment responses of IgA EBA were analyzed in a case series including 4 patients with IgA EBA. All patients from the database of the autoimmune diagnostic laboratory at the Department of Dermatology, University of Lübeck, Germany, who were diagnosed with IgA EBA, LABD, or IgG EBA between October 2010 and July 2019 were included. Four patients diagnosed with IgA EBA between October 2015 and January 2018 are described in detail.

Main Outcomes and Measures

The clinical course of IgA EBA was observed before and during different treatments.

Results

The database search yielded 21 cases of IgA EBA (12 females [57%]/9 males [43%]), 222 cases of LABD (111 females [51%]/106 males [49]), and 57 cases of IgG EBA (29 females [50%]/28 males [48%]). The median (range) age of each cohort was 64 (4-81) years for IgA EBA, 56 (3-92) years for IgG EBA, and significantly older compared with IgG EBA (P = .002) for those with LAPD (median [range], 70 [1-94] years). The patients with IgA EBA exhibited heterogeneous clinical presentations that significantly differed from those of anti-BP180 LABD. All 4 patients with IgA EBA described in detail were first treated with dapsone, but only 1 responded to this treatment. The others required treatment with high-dose dexamethasone, rituximab, and/or intravenous immunoglobulins to achieve partial clinical remission.

Conclusions and Relevance

Overall, the findings of this cohort study and small case series suggest that IgA EBA may be more common than expected and may require more intensive systemic treatment than LABD, suggesting it should be considered a separate disease entity.

Use of Convolutional Neural Networks for the Detection of u-Serrated Patterns in Direct Immunofluorescence Images to Facilitate the Diagnosis of Epidermolysis Bullosa Acquisita

The u-serrated immunodeposition pattern in direct immunofluorescence (DIF) microscopy is a recognizable feature and confirmative for the diagnosis of epidermolysis bullosa acquisita (EBA). Due to unfamiliarity with serrated patterns, serration pattern recognition is still of limited use in routine DIF microscopy. The objective of this study was to investigate the feasibility of using convolutional neural networks (CNNs) for the recognition of u-serrated patterns that can assist in the diagnosis of EBA. The nine most commonly used CNNs were trained and validated by using 220,800 manually delineated DIF image patches from 106 images of 46 different patients. The data set was split into 10 subsets: nine training subsets from 42 patients to train CNNs and the last subset from the remaining four patients for a validation data set of diagnostic accuracy. This process was repeated 10 times with a different subset used for validation. The best-performing CNN achieved a specificity of 89.3% and a corresponding sensitivity of 89.3% in the classification of u-serrated DIF image patches, an expert level of diagnostic accuracy. Experiments and results show the effectiveness of CNN approaches for u-serrated pattern recognition with a high accuracy. The proposed approach can assist clinicians and pathologists in recognition of u-serrated patterns in DIF images and facilitate the diagnosis of EBA.

Anti-P 200 pemphigoid - The most common floor binding subepidermal autoimmune bullous disease in a tertiary care center in south India

BACKGROUND

The pemphigoid group of diseases may present clinically and immunologically in a very similar fashion. Indirect immunofluorescence microscopy with readily available salt-split human skin in a BIOCHIP™ helps to classify these conditions as those with either with roof binding or floor binding of immunoreactants. Epidermolysis bullosa acquisita, anti-laminin 332 pemphigoid and anti-p200 pemphigoid show floor binding, while in the most frequent type of pemphigoid disease, bullous pemphigoid, epidermal side staining pattern is seen on salt-split skin Aims: The aim of the study was to detect the target antigens in sub-epidermal bullous diseases.

METHODS

Forty patients with bullous pemphigoid diagnosed by lesional histopathology and direct immunofluorescence microscopy were re-evaluated by a BIOCHIP™ mosaic containing both tissue substrates and recombinant target antigens. Sera with floor pattern staining on salt-split skin were further evaluated by immunoblotting with dermal extract.

RESULTS

Five patients with floor staining had anti-p200 pemphigoid.

LIMITATIONS

We could not perform serration pattern analysis of direct immunofluorescence in our patients.

CONCLUSION

Histopathology and direct immunofluorescence microscopy cannot differentiate between various entities of pemphigoid diseases. A multivariant approach using a BIOCHIP™ mosaic including salt-split skin followed by immunoblotting with dermal extract helps to identify the target antigen.

Assessment of Diagnostic Strategy for Mucous Membrane Pemphigoid

Importance

An accurate diagnosis of mucous membrane pemphigoid (MMP) is essential to reduce diagnostic and therapeutic delay.

Objective

To assess the diagnostic accuracy of direct immunofluorescence microscopy on mucosal biopsy specimens and immunoserology in a large cohort of patients with suspected MMP.

Design, Setting, and Participants

This retrospective cohort study was carried out in a single tertiary care center for blistering diseases between January 2002 and March 2019. Eligible participants were patients with suspected MMP and paired data on at least a mucosal biopsy specimen for direct immunofluorescence microscopy (DIF) and indirect immunofluorescence microscopy (IIF) on a human salt-split skin substrate (SSS). In addition, an optional DIF test on a skin biopsy specimen and one or more performed routine immunoserologic tests were analyzed. Data analysis was conducted from April 2019, to June 2020.

Main Outcomes and Measures

Diagnostic accuracy of DIF, IIF SSS, and immunoblot for BP180 and BP230.

Results

Of the 787 participants, 121 (15.4%) received the diagnosis of MMP (50 men [41.3%], 71 women [58.7%]; mean [SD] age at diagnosis, 60.1 [17.7] years). Sixty-seven of the patients with MMP (55.4%) had monosite involvement, of which oral site was the most frequently affected (51 [42.1%]). No significant difference was found between the sensitivity of DIF on a perilesional buccal biopsy and a normal buccal biopsy (89.3% vs 76.7%). Three patients with solitary ocular involvement showed a positive DIF of only the oral mucosa. In 6 patients with a negative mucosal DIF, a skin biopsy confirmed diagnosis of MMP. Overall, IIF SSS was less sensitive (44.6%), but highly specific (98.9%). The sensitivity of immunoblot (66.1%) was higher compared to SSS, but with lower specificity (91.3%).

Conclusions and Relevance

This comparative diagnostic accuracy study of a cohort of 787 patients found a high sensitivity of a mucosal DIF biopsy for diagnosis of MMP, and lower sensitivity of serologic analysis. A biopsy can be taken from either perilesional or normal buccal mucosa. An additional DIF biopsy of another mucosal site or of affected or unaffected skin may increase the diagnostic yield and is recommended in patients with negative DIF results and high clinical suspicion.

Subepithelial autoimmune blistering dermatoses: Clinical features and diagnosis

Subepithelial autoimmune blistering dermatoses are a group of rare skin disorders that are characterized by the disruption of the dermal-epidermal junction through the action of autoantibodies. The third article in this continuing medical education series explores the background, epidemiology, clinical features, and diagnostic criteria of each of the major subepithelial autoimmune blistering dermatoses, including bullous pemphigoid, pemphigoid gestationis, lichen planus pemphigoides, mucous membrane pemphigoid, linear IgA bullous dermatosis, and dermatitis herpetiformis.

Milestones in Personalized Medicine in Pemphigus and Pemphigoid

Pemphigus and pemphigoid diseases are autoimmune bullous diseases characterized and caused by autoantibodies targeting adhesion molecules in the skin and/or mucous membranes. Personalized medicine is a new medical model that separates patients into different groups and aims to tailor medical decisions, practices, and interventions based on the individual patient`s predicted response or risk factors. An important milestone in personalized medicine in pemphigus and pemphigoid was achieved by verifying the autoimmune pathogenesis underlying these diseases, as well as by identifying and cloning several pemphigus/pemphigoid autoantigens. The latter has become the basis of the current, molecular-based diagnosis that allows the differentiation of about a dozen pemphigus and pemphigoid entities. The importance of autoantigen-identification in pemphigus/pemphigoid is further highlighted by the emergence of autoantigen-specific B cell depleting strategies. To achieve this goal, the chimeric antigen receptor (CAR) T cell technology, which is used for the treatment of certain hematological malignancies, was adopted, by generating chimeric autoantigen receptor (CAAR) T cells. In addition to these more basic science-driven milestones in personalized medicine in pemphigus and pemphigoid, careful clinical observation and epidemiology are again contributing to personalized medicine. The identification of clearly distinct clinical phenotypes in pemphigoid like the non-inflammatory and gliptin-associated bullous pemphigoid embodies a prominent instance of the latter. We here review these exciting developments in basic, translational, clinical, and epidemiological research in pemphigus and pemphigoid. Overall, we hereby aim to attract more researchers and clinicians to this highly interesting and dynamic field of research.

[Modern diagnostics of autoimmune bullous diseases]

Blisters and erosions of skin and mucous membranes are key features of the clinically heterogeneous group of autoimmune bullous diseases (AIBDs). These can be divided into pemphigoid diseases with autoantibodies against structural proteins of the dermal-epidermal junction, pemphigus diseases with autoantibodies against desmosomal proteins, and dermatitis herpetiformis with autoantibodies against transglutaminases 1 and 2. A differentiation based only on clinical features is often not sufficient. After researching the literature in PubMed, the current diagnostic tools for AIBDs are summarized.AIBD diagnostics are performed using histology, direct and indirect immunofluorescence, as well as ELISA and immunoblotting. For serological diagnosis, the conventional multistep approach or multivariant assays for the analysis of autoantibodies against several target antigens in parallel can be applied. These allow a precise classification of AIBD and therefore a tailored use of different therapeutic regimens, e.g., for bullous pemphigoid or pemphigus foliaceus/vulgaris, as well as identification of disease entities with a known association with neoplasia.Direct immunofluorescence is still the diagnostic mainstay of AIBDs. However, novel serological assays, such as target-antigen-specific ELISA or indirect immunofluorescence systems using BIOCHIP™ mosaic technology, allow serologic diagnosis in most AIBD patients and the exact classification of the disease entity at the molecular level.

Oral Lesions in Autoimmune Bullous Diseases: An Overview of Clinical Characteristics and Diagnostic Algorithm

Autoimmune bullous diseases are a group of chronic inflammatory disorders caused by autoantibodies targeted against structural proteins of the desmosomal and hemidesmosomal plaques in the skin and mucosa, leading to intra-epithelial or subepithelial blistering. The oral mucosa is frequently affected in these diseases, in particular, in mucous membrane pemphigoid, pemphigus vulgaris, and paraneoplastic pemphigus. The clinical symptoms are heterogeneous and may present with erythema, blisters, erosions, and ulcers localized anywhere on the oral mucosa, and lead to severe complaints for the patients including pain, dysphagia, and foetor. Therefore, a quick and proper diagnosis with adequate treatment is needed. Clinical presentations of autoimmune bullous diseases often overlap and diagnosis cannot be made based on clinical features alone. Immunodiagnostic tests are of great importance in differentiating between the different diseases. Direct immunofluorescence microscopy shows depositions of autoantibodies along the epithelial basement membrane zone in mucous membrane pemphigoid subtypes, or depositions on the epithelial cell surface in pemphigus variants. Additional immunoserological tests are useful to discriminate between the different subtypes of pemphigoid, and are essential to differentiate between pemphigus and paraneoplastic pemphigus. This review gives an overview of the clinical characteristics of oral lesions and the diagnostic procedures in autoimmune blistering diseases, and provides a diagnostic algorithm for daily practice.

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.

Advances in the diagnosis of autoimmune bullous dermatoses

Autoimmune bullous dermatoses are defined by autoantibodies directed against adhesion proteins in the epidermis or basement membrane zone, resulting in blister formation on the skin and mucosa. Diagnosis depends on lesional biopsy for histopathology and perilesional biopsy for direct immunofluorescence. Additional diagnostic methods include indirect immunofluorescence, enzyme-linked immunosorbent assay, and immunoblot (Western blot), which may be selected in specific clinical scenarios due to improved sensitivity and/or specificity. This contribution reviews the available evidence supporting the use of each method to provide a practical reference for clinicians when diagnosing autoimmune bullous disorders. Techniques and cost are reviewed, and newer diagnostic techniques with potential for clinical application are.

Serological Diagnosis of Autoimmune Bullous Skin Diseases

Autoimmune bullous dermatoses (AIBD) encompass a variety of organ-specific autoimmune diseases that manifest with cutaneous and/or mucosal blisters and erosions. They are characterized by autoantibodies targeting structural proteins of the skin, which are responsible for the intercellular contact between epidermal keratinocytes and for adhesion of the basal keratinocytes to the dermis. The autoantibodies disrupt the adhesive functions, leading to splitting and blister formation. In pemphigus diseases, blisters form intraepidermally, whereas in all other disease types they occur subepidermally. Early identification of autoimmune bullous dermatoses is crucial for both treatment and prognosis, particularly as regards tumor-associated disease entities. The diagnosis is based on clinical symptoms, histopathology, direct immunofluorescence to detect antibody/complement deposits, and the determination of circulating autoantibodies. The identification of various target antigens has paved the way for the recent development of numerous specific autoantibody tests. In particular, optimized designer antigens and multiplex test formats for indirect immunofluorescence and ELISA have enhanced and refined the laboratory analysis, enabling highly efficient serodiagnosis and follow-up. This review elaborates on the current standards in the serological diagnostics for autoimmune bullous dermatoses.

Consensus on the treatment of autoimmune bullous dermatoses: bullous pemphigoid, mucous membrane pemphigoid and epidermolysis bullosa acquisita - Brazilian Society of Dermatology

Bullous pemphigoid, mucous membrane pemphigoid and epidermolysis bullosa acquisita are subepidermal autoimmune blistering diseases whose antigenic target is located at the basement membrane zone. Mucous membrane pemphigoid and epidermolysis bullosa acquisita can evolve with cicatricial mucosal involvement, leading to respiratory, ocular and/or digestive sequelae with important morbidity. For each of these dermatoses, a literature review covering all therapeutic options was performed. A flowchart, based on the experience and joint discussion among the authors of this consensus, was constructed to provide treatment orientation for these diseases in Brazil. In summary, in the localized, low-risk or non-severe forms, drugs that have immunomodulatory action such as dapsone, doxycycline among others may be a therapeutic option. Topical treatment with corticosteroids or immunomodulators may also be used. Systemic corticosteroid therapy continues to be the treatment of choice for severe forms, especially those involving ocular, laryngeal-pharyngeal and/or esophageal mucosal involvement, as may occur in mucous membrane pemphigoid and epidermolysis bullosa acquisita. Several immunosuppressants are used as adjuvant alternatives. In severe and recalcitrant cases, intravenous immunoglobulin is an alternative that, while expensive, may be used. Immunobiological drugs such as rituximab are promising drugs in this area. Omalizumab has been used in bullous pemphigoid.

[What's new in clinical dermatology?]

In this article, we performed a review of all new data of clinical relevance for the dermatologists that were published in the medical literature between September, 2017 and September, 2018. Besides advances that will be useful in day-to-day dermatological practice, we intended to give a more general perspective to this review by taking into account certain international health issues that might in final concern each of us in a globalized world. Focus were more particularly done on the following topics: infectious diseases (including sexually transmitted infections), neglected tropical diseases, adverse effects of drugs, bullous diseases, allergology, wound healing, dermatology on black skin, and public health dermatology.

Pemphigoid variants affecting the skin

Pemphigoid diseases are autoimmune subepidermal blistering diseases affecting the skin and mucous membranes, which are caused by autoantibodies targeting structural hemidesmosomal proteins or hemidesmosome-associated proteins. Variants of pemphigoid can be differentiated based on targeted antigens and clinical aspects. In this review, we will discuss pemphigoid variants that predominantly affect the skin, and provide clinicians with clues to diagnosis.

[Epidermolysis bullosa acquisita]

Epidermolysis bullosa acquisita (EBA) is a rare acquired subepidermal bullous autoimmune dermatosis, associated with autoantibodies against collagen type VII, the most important component of dermal anchoring fibrils. Blister induction occurs after binding of autoantibodies to collagen type VII, leading to complement activation, recruitment of neutrophils and secretion of proteases. Clinically, the disease is mostly characterized by tense blisters on trauma-exposed body areas which heal with scarring (mechanobullous form of EBA). The second most frequent subtype of EBA is inflammatory EBA, a bullous pemphigoid-like disease associated with pruritus. Involvement of mucous membranes and/or lesions in the head and neck area additionally point to the diagnosis of EBA. The mechanobullous type of EBA and EBA with intensive mucous membrane lesions display a chronic course and are often extremely resistant to therapy. Topical and systemic glucocorticoids, dapsone, colchicine, classical immunosuppressants, anti-CD20 antibodies, immunoadsorption or intravenous immunoglobulins have been reported as treatments.

Drug Discovery for Pemphigoid Diseases

Pemphigoid diseases (PDs) are a group of autoimmune bullous diseases characterized and caused by autoantibodies targeting structural proteins of the skin and mucous membranes. Chronic inflammation, subepidermal blistering, and often scaring are the clinical characteristics of PDs. Itching and, in severe cases, disabilities resulting from scaring (i.e., blindness, esophageal strictures) are the leading subjective symptoms. Treatment of PDs, which is based on nonspecific immunosuppression, is challenging because of frequent relapses, lack of efficacy, and numerous adverse events. In addition, the incidence of PDs is increasing. Given the high morbidity, limited therapeutic options, and increasing incidence, there is a growing urgency for drug discovery to help treat this condition. The recent development of PD model systems has added to the understanding of PD pathogenesis and, based on these insights, new clinical trials will soon be launched. The (auto-)antibody transfer PD models allow for investigations into autoantibody-mediated tissue pathology, while immunization-induced PD models more closely resemble the clinical situation. The latter duplicate all aspects of the human disease and are useful for investigating PD pathogenesis and testing therapeutic interventions. This article describes antibody transfer and immunization-induced PD mouse models currently employed for translational PD research. © 2019 by John Wiley & Sons, Inc.

Epidermolysis Bullosa Acquisita: The 2019 Update

Epidermolysis bullosa acquisita (EBA) is an orphan autoimmune disease. Patients with EBA suffer from chronic inflammation as well as blistering and scarring of the skin and mucous membranes. Current treatment options rely on non-specific immunosuppression, which in many cases, does not lead to a remission of treatment. Hence, novel treatment options are urgently needed for the care of EBA patients. During the past decade, decisive clinical observations, and frequent use of pre-clinical model systems have tremendously increased our understanding of EBA pathogenesis. Herein, we review all of the aspects of EBA, starting with a detailed description of epidemiology, clinical presentation, diagnosis, and current treatment options. Of note, pattern analysis via direct immunofluorescence microscopy of a perilesional skin lesion and novel serological test systems have significantly facilitated diagnosis of the disease. Next, a state-of the art review of the current understanding of EBA pathogenesis, emerging treatments and future perspectives is provided. Based on pre-clinical model systems, cytokines and kinases are among the most promising therapeutic targets, whereas high doses of IgG (IVIG) and the anti-CD20 antibody rituximab are among the most promising "established" EBA therapeutics. We also aim to raise awareness of EBA, as well as initiate basic and clinical research in this field, to further improve the already improved but still unsatisfactory conditions for those diagnosed with this condition.

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.

Diagnosis of anti-laminin γ-1 pemphigoid by immunoblot analysis

BACKGROUND

Anti-laminin-γ1 (lam-γ1) pemphigoid, a recently described immunobullous disorder sharing immune serological features of bullous pemphigoid and epidermolysis bullosa acquisita (EBA), is characterized by the detection of serum IgG autoantibodies against the lam-γ1 chain, a 200 kDa heterotrimeric component of the dermal-epidermal junction (DEJ).

OBJECTIVE

The aim of the study was to develop an easy-to-perform and reliable assay for the serological detection of anti-lam-γ1 IgG autoantibodies. The clinical appearance alone is not sufficient to establish diagnosis of anti-lam-γ1 pemphigoid and rather requires immune serological evidence of (i) IgG reactivity against the dermal portion of salt-split human skin; (ii) exclusion of IgG against other components of the DEJ; and (iii) IgG reactivity with a 200 kDa protein of dermal extracts by immunoblot analysis (IB).

METHODS

The sera of 55 patients with anti-lam-γ1 pemphigoid were tested by IB with two recombinant heterotrimers, laminin 111 (lam-111) and laminin 421 (lam-421), as well as with a recombinant lam-γ1 chain monomer. Additionally, a total of 41 control sera from patients with EBA (n = 15), psoriasis vulgaris (PV; n = 14), and healthy controls (HC; n = 12) were tested.

RESULTS

Immunoblot analysis revealed a positive reactivity with lam-111 and/or lam-421 in 46/55 (84%) of anti-lam-γ1 pemphigoid sera. Moreover, 8/9 of the initially non-reactive sera were positive with the lam-γ1 monomer, leading to an overall sensitivity of 98.2%. Analyses of 41 control sera with the three lam-γ1 recombinants led to a specificity of 88%. Specifically, 3/15 EBA sera, 1/14 PV serum and 1/12 HC serum reacted with the lam-γ1 monomer while only the 3 EBA sera reacted with lam-421.

CONCLUSIONS

Here we show a novel two-step IB assay using the two recombinant laminin trimers and lam-γ1 chain monomer for the detection of anti-lam-γ1 serum IgG with high sensitivity and specificity. This assay will facilitate the diagnosis and further characterization of this disease.