BPDAI and ABSIS correlate with serum anti-BP180 NC16A IgG but not with anti-BP230 IgG in patients with bullous pemphigoid

Clinical characteristics of bullous pemphigoid patients of different ages and the possible mechanism

Bullous pemphigoid (BP) is an acquired autoimmune bullous disease that often occurs in elderly patients. Some BP patients with early age of disease onset were observed to have difficulty in receiving applicable disease control. It remains challenging for clinicians to choose the appropriate treatment for these patients. This study aimed to analyze the differences between patients of different ages at disease onset and further explore the possible mechanism of these differences between patients of different ages. A total of 215 BP patients seen at the dermatology department of Peking Union Medical College Hospital between January 2009 and September 2020 were included. The patients were allocated to five groups according to the age at disease onset. Clinical data were collected through medical records and telephone follow-up interviews. Analyses of anti-BP180 antibody subclasses, anti-BP230 antibodies, complement fixation, serum cytokine levels, and single nucleotide polymorphisms (SNPs) were conducted. Nearly 52% of patients under 60 were misdiagnosed on their first visit, often presenting with oral mucosal involvement. The anti-BP180 immunoglobulin (Ig) E titers and C3 deposition increased in patients under 60 (p = 0.044 and p = 0.014, respectively), while the anti-BP230 IgG titers decreased (p = 0.043). The hospitalization rate of patients under 50 was significantly higher than that of patients aged 80 and older (p < 0.001). The patients under 60 had a significantly higher serum concentration of interleukin (IL)-13, tumor necrosis factor (TNF)-α, and interferon gamma (IFN-γ) (p < 0.005, respectively). We observed significant differences in the distribution of genotypes or alleles of TNF-α rs1799964, TNF-α rs1800630, and IFN-γ rs2069705. Approximately one-third of the elderly patients suffered from neurological diseases. Elderly patients usually presented with peripheral eosinophilia (p = 0.013). No significant difference was identified in the recurrence rate and complement-activating capacity among the age groups. In conclusion, the early age of BP onset was associated with a more severe clinical presentation, higher titers of anti-BP180 IgE, lower titers of anti-BP230 IgG, and significantly higher serum concentrations of IL-13, TNF-α, and IFN-γ. It may also be associated with the presence of SNPs of cytokines, including TNF-α rs1799964, TNF-α rs1800630, and IFN-γ rs2069705 variants.

Bullous pemphigoid

Bullous pemphigoid is a chronic, subepidermal autoimmune blistering disease characterized by tense blisters on erythematous or normal skin that predominantly affects the older population. The disease arises from autoantibodies targeting hemidesmosomal proteins BP180 and BP230, which are crucial for dermal-epidermal adhesion. The incidence of bullous pemphigoid is increasing, attributed to an ageing population and improved diagnostic recognition. Genetic predisposition, environmental triggers and associations with other autoimmune disorders underline its multifactorial nature. Diagnosis involves clinical presentation, histopathology, direct immunofluorescence and serological tests. Treatment aims to reduce symptoms and prevent new blister formation, using corticosteroids, immunosuppressive agents and biologics such as rituximab and omalizumab. Despite therapeutic advancements, challenges persist in long-term management, especially in older patients with comorbidities. Ongoing research into molecular mechanisms and novel therapeutic targets and clinical trials are crucial for the development of safer and more effective treatments.

Bullous Pemphigoid Severity and Levels of Antibodies to BP180 and BP230: A Systematic Review and Meta-Analysis

Importance

The correlation between serum levels of autoantibodies against bullous pemphigoid (BP) antigens 180 (BP180) and 230 (BP230) with BP disease severity is unclear.

Objective

To investigate the correlation of anti-BP180 and anti-BP230 immunoglobulin G (IgG) antibody levels with BP disease severity.

Data Sources

A search was performed of the Cochrane Central Register of Controlled Trials, Embase, and PubMed databases from their respective inception to April 11, 2024.

Study Selection

Studies evaluating the correlation between serum levels of anti-BP180 or anti-BP230 IgG measured using enzyme-linked immunosorbent assay (ELISA) and disease severity assessed per the Autoimmune Bullous Skin Disorder Intensity Score (ABSIS) or BP Disease Area Index (BPDAI) were included. No language or geographic restrictions were imposed. Nearly 0.4% of initially identified studies met the selection criteria.

Data Extraction and Synthesis

One researcher extracted data and another researcher confirmed data. The risk of bias was independently assessed by these researchers using the Quality Assessment of Diagnostic Accuracy Studies 2 tool, with discrepancies resolved by discussion with a third researcher. A random-effects model meta-analysis and a subgroup analysis were conducted based on the ELISA kit manufacturers.

Main Outcomes and Measures

Pooled correlation coefficients of antibody levels with ABSIS and BPDAI.

Results

In all, 14 studies with 1226 participants were analyzed. The risk of bias of included studies was generally low. The meta-analysis found anti-BP180 autoantibody levels showed moderate correlation with objective BPDAI (r = 0.56; 95% CI, 0.46-0.64) at baseline, strong correlation (r = 0.63; 95% CI, 0.39-0.79) at 3-month follow-up, and moderate correlation (r = 0.53; 95% CI, 0.25-0.72) at 6-month follow-up. Anti-BP180 autoantibody levels also showed moderate correlation (r = 0.52; 95% CI, 0.39-0.62) with ABSIS at baseline, strong correlation (r = 0.62; 95% CI, 0.39-0.79) at 3-month follow-up, and moderate correlation (r = 0.53; 95% CI, 0.25-0.72) at 6-month follow-up. By contrast, anti-BP230 autoantibody levels showed no association with objective BPDAI and ABSIS at diagnosis and follow-up. The subgroup analysis found similar results when using different ELISA kits.

Conclusions and Relevance

The findings of this systematic review and meta-analysis indicated that anti-BP180 autoantibody levels may serve as an adjunctive tool for monitoring BP disease severity and guiding clinical care for patients with BP.

Anti-BP230 IgE autoantibodies in bullous pemphigoid intraindividually correlate with disease activity

BACKGROUND

Bullous pemphigoid (BP), the most common subepidermal autoimmune blistering disease, is classically defined by the presence of IgG autoantibodies directed against the hemidesmosomal proteins BP180 (type XVII collagen) and BP230 and the predominance of skin lesions. Several studies have addressed the role of anti-BP180 IgE in patients and experimental models, while data on anti-BP230 IgE are scarce.

OBJECTIVE

To assess anti-BP230 IgE level by ELISA in BP sera and to correlate it with disease severity and clinical characteristics.

METHODS

BP sera underwent anti-BP230 IgE ELISA and Western blotting against human BP230 fragments.

RESULTS

We demonstrate that 36/154 (23%) of BP sera were positive for anti-BP230 IgE. Anti-BP230 IgE levels had no correlation with clinical phenotype or disease activity per se. Interestingly, anti-BP230 IgE was significantly associated with disease activity within individuals during the course of the disease. Additionally, anti-BP230 IgE and total IgE levels showed a significant correlation. Notably, anti-BP230 IgG correlated interindividually with disease activity. By Western blotting, the C-terminal domain of BP230 fragments (C2; amino acids 2024-2349 and C3; amino acids 2326-2649), provided the best serological assay for anti-BP230 IgE detection.

CONCLUSION

As a complementary tool, IgE immunoblotting is recommended to obtain an optimal serological diagnosis, particularly in patients with severe disease without IgG reactivity by BP180- or BP230-specific ELISA. Although the detection of serum anti-BP230 IgE is not of major diagnostic significance, it may be relevant for therapeutic decisions, e.g., for anti-IgE-directed treatment, which has been successfully used in case series of BP.

Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio are positively correlated with disease activity of bullous pemphigoid

Bullous pemphigoid (BP) is a complex inflammatory process with elevated levels of autoantibodies, eosinophils, neutrophils, and various cytokines. Hematological inflammatory biomarkers can reflect inflammatory state in various diseases. Up to now, the correlations of hematological inflammatory biomarkers and disease activity of BP remain unknown. The purpose of this study was to clarify the associations between hematological inflammatory biomarkers and disease activity of BP. The levels of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), platelet-to-neutrophil ratio (PNR) and mean platelet volume (MPV) of 36 untreated BP patients and 45 age and gender matched healthy controls were detected by routine blood tests. The correlations between hematological inflammatory markers and clinical characteristics of BP were statistically analyzed. The Bullous Pemphigoid Disease Area Index (BPDAI) was used to measure disease activity of BP. The mean levels of NLR, PLR, PNR and MPV in 36 untreated BP patients were 3.9, 157.9, 45.7 and 9.4 fl, respectively. Increased NLR (p < 0.001), PLR (p < 0.01), and MPV (p < 0.001) but decreased PNR (p < 0.001) were observed in BP patients when compared with healthy controls. In BP patients, the levels of NLR were positively correlated to BPDAI Erosion/Blister Scores (p < 0.01); and the levels of NLR and PLR were both positively correlated to BPDAI without Damage Score (both p < 0.05) and BPDAI Total Score (both p < 0.05). No correlation was found in other statistical analyses between hematological inflammatory markers and clinical characteristics in BP patients involved in the present study. Therefore, NLR and PLR are positively correlated with disease activity of BP.

Pemphigus and pemphigoids: Clinical presentation, diagnosis and therapy

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

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

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

Evaluation of Dupilumab in Patients With Bullous Pemphigoid

Importance

Dupilumab is a theoretically novel therapy for bullous pemphigoid (BP). However, its effectiveness and safety have yet to be confirmed in a large-scale study.

Objective

To assess the efficacy and safety of dupilumab in patients with BP and evaluate factors that potentially affect short-term and long-term outcomes.

Design, Setting, and Participants

A retrospective cohort study was conducted from January 1, 2021, to July 31, 2022. The median (IQR) follow-up period was 24.6 (11.5-38.4) weeks. This multicenter study was performed in 6 dermatology departments of the National Autoimmune Bullous Diseases Cooperative Group of China. Adult patients with BP that received 300 mg of dupilumab every 2 weeks following an initial dose of 600 mg were included. Patients were eligible if they had a clinical presentation of BP combined with immunological or pathological evidence. Patients with drug-induced BP, with less than 4 weeks of follow-up, and who received dupilumab or any other biologics within 6 months were excluded.

Main Outcomes and Measures

The primary outcome was the proportion of patients who achieved disease control within 4 weeks. Disease control was defined as the absence of new lesions and pruritus, combined with the healing of existing lesions. Complete remission rates, relapse rates, changes in Bullous Pemphigoid Disease Area Index (BPDAI) scores, itching numerical rating scale (NRS) scores, laboratory results within 64 weeks, and adverse events (AEs) were also assessed.

Results

Among 146 patients (median [IQR] age, 73 [64-85] years; 86 [58.9%] male patients) included in the study, 127 (87.0%) patients achieved disease control within 4 weeks, with a median (IQR) time of 14 (7-14) days. A total of 52 (35.6%) patients achieved complete remission, and 13 (8.9%) patients relapsed during the observation period. The complete remission rate and cumulative relapse rate at week 64 were 62.5% (5 of 8) and 30.9%, respectively. There was rapid and sustained improvement in clinical indicators and laboratory examination results after dupilumab treatment, including BPDAI scores, itching NRS scores, serum anti-BP180 and anti-BP230 antibodies, total IgE levels, and eosinophil count. Of these 146 patients, 107 (73.3%) did not report any AEs. The most common AEs were infections and eosinophilia. Serum anti-BP180 antibody levels of greater than 50 relative units (RU)/mL (OR, 3.63; 95% CI, 0.97-12.61; P = .045) were associated with 4-week disease control, and male patients were more likely to relapse (HR, 10.97; 95% CI, 1.42-84.92; P = .02).

Conclusions and Relevance

In this retrospective cohort study, dupilumab treatment was associated with improved clinical symptoms in patients with BP. The safety profile was favorable, although concurrent infection and eosinophilia might pose potential concerns. This study suggests that patients with anti-BP180 antibody levels of at least 50 RU/mL and female sex may respond better.

Bullous pemphigoid: The role of type 2 inflammation in its pathogenesis and the prospect of targeted therapy

Bullous pemphigoid (BP) is an autoimmune disease that mainly occurs in the elderly, severely affecting their health and life quality. Traditional therapy for BP is mainly based on the systemic use of corticosteroids, but long-term use of corticosteroids results in a series of side effects. Type 2 inflammation is an immune response largely mediated by group 2 innate lymphoid cells, type 2 T helper cells, eosinophils, and inflammatory cytokines, such as interleukin (IL)-4, IL-5 and IL-13. Among patients with BP, the levels of immunoglobulin E and eosinophils are significantly increased in the peripheral blood and skin lesions, suggesting that the pathogenesis is tightly related to type 2 inflammation. To date, various targeted drugs have been developed to treat type 2 inflammatory diseases. In this review, we summarize the general process of type 2 inflammation, its role in the pathogenesis of BP and potential therapeutic targets and medications related to type 2 inflammation. The content of this review may contribute to the development of more effective drugs with fewer side effects for the treatment of BP.

Evaluation of the immune colloidal gold technique for BP180-NC16A-specific antibodies in the quick diagnosis and monitoring of bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) mostly involves elderly patients. The diagnosis of BP requires special immunological tests, which makes some patients unable to be diagnosed and treated timely.

OBJECTIVE

The accuracy and application value of immune colloidal gold technique (ICGT) in BP were evaluated. The colloidal gold was conjugated with recombinant BP180 NC16A protein and mouse IgG antibody. As the test and control lines, the mouse-anti-human IgG and goat-anti-mouse IgG, respectively, were blotted on the nitrocellulose membrane.

METHODS

414 serum samples of consecutive patients with suspected BP and 15 samples from healthy donors were recruited. The consistency between ICGT and ELISA, and between serum and plasma/whole blood were evaluated. Subgroup analyses were performed in terms of clinical characteristics. We also followed up 65 BP patients' strip results to explore the predictive value of ICGT.

RESULTS

Strong agreements between ICGT and ELISA(κ = 0.902) and between plasma/whole blood and serum samples (κ = 0.980) with good stability were observed. The ICGT achieved sensitivity of 93.9%, and specificity of 97.6%. In subgroup analysis, the sensitivity was significantly higher in older patients (96.3%), and with more typical lesions such as blisters (96.2%) and erosions (92.4%). In follow-up, we also found BP patients who kept ICGT-negative in remission state all got consecutive positive strips 1-3 weeks prior to mild new activity or flare.

CONCLUSION

ICGT shows high potential as a rapid and stable option for the diagnosis and monitoring of BP. Further investigations are needed to re-evaluate this technique in a prospective study with a multicenter design.

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.

Bullous pemphigoid: Three main clusters defining 3 outcome profiles

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune blistering disorder. Its presentation is polymorphic.

OBJECTIVE

To investigate different clinical and biological profiles of BP.

METHODS

We conducted a retrospective 2-center study including all BP patients seen between January 1, 2015, and February 28, 2021. We performed hierarchical clustering on principal components.

RESULTS

Three clusters were identified. Patients in cluster 1 (n = 155) were older than those in clusters 2 (n = 89) and 3 (n = 35; P < .0001), more frequently presented pauci-bullous BP (n = 63 [41%] vs 14 [16%] and 2 [6%], respectively; P < .0001) and had anti-BP230 antibodies in 87% of cases. More than 100 blisters were observed in 14 patients (40%) from cluster 3, versus 3 (2%) from cluster 1 and 0 (0%) from cluster 2 (P < .0001). Frequency of mucosal involvement was higher in cluster 3 (n = 32 [91%, including epiglottis in 40%] vs 11 [7%] and 34 [38%]; P < .0001). In clusters 2 and 3, 70% and 74% of patients had antibodies targeting only BP180. Those in cluster 3 received more lines of systemic treatment and experienced more relapses.

LIMITATIONS

Retrospective study without immunoelectron microscopy.

CONCLUSION

We identified 3 different BP clusters, including one corresponding to severe BP180⁺ BP230^- BP with features common to mucous membrane pemphigoid.

Serum autoantibody reactivity in bullous pemphigoid is associated with neuropsychiatric disorders and the use of antidiabetics and antipsychotics: a large prospective cohort study

BACKGROUND

Bullous pemphigoid (BP), the by far most frequent autoimmune blistering skin disease (AIBD), is immunopathologically characterized by autoantibodies against the two hemidesmosomal proteins BP180 (collagen type XVII) and BP230 (BPAG1 or dystonin). Several comorbidities and potentially disease-inducing medication have been described in BP, yet, a systematic analysis of these clinically relevant findings and autoantibody reactivities has not been performed.

OBJECTIVE

To determine associations of autoantibody reactivities with comorbidities and concomitant medication.

METHODS

In this prospective multicenter study, 499 patients diagnosed with BP in sixteen European referral centers were included. The relation between anti-BP180 NC16A and anti-BP230 IgG ELISA values at the time of diagnosis as well as comorbidities and concomitant medication collected by a standardized form were analyzed.

RESULTS

An association between higher serum anti-BP180 reactivity and neuropsychiatric but not atopic and metabolic disorders was observed as well as with the use of insulin or antipsychotics but not with dipeptidyl peptidase-4 (DPP4) inhibitors, inhibitors of platelet aggregation and L-thyroxine. The use of DPP4 inhibitors was associated with less anti-BP180 and anti-BP230 reactivity compared to BP patients without these drugs. This finding was even more pronounced when compared with diabetic BP patients without DPP4 inhibitors. Associations between anti-BP180 and anti-BP230 reactivities were also found in patients using insulin and antipsychotics, respectively, compared with patients without this medication, but not for the use of inhibitors of platelet aggregation, and L-thyroxine.

CONCLUSION

Taken together, these data imply a relation between autoantibody reactivities at the time of diagnosis and both neuropsychiatric comorbidities as well as distinct concomitant medication suggesting a link between the pathological immune mechanisms and clinical conditions that precede the clinically overt AIBD.

A Cross-Sectional Study to Correlate Disease Severity in Bullous Pemphigoid Patients with Serum Levels of Autoantibodies Against BP180 and BP230

Context:

Enzyme-linked immunosorbent assay (ELISA) for BP 180 and 230 antibodies is commonly done in patients with bullous pemphigoid. We could not find much data regarding the usefulness of this test to predict the disease severity in Indian population.

Aims:

We studied the correlation of IgG anti BP180 and anti BP230 antibody titer with disease severity and clinical features in bullous pemphigoid.

Settings and Design:

This cross-sectional study was conducted at a tertiary care center in western India.

Materials and Methods:

Forty-two clinically diagnosed treatment-naive cases of bullous pemphigoid were enrolled and investigated with skin punch biopsy, IgG anti BP180, and anti BP230 ELISA, direct immunofluorescence, and indirect immunofluorescence tests. Disease severity was assessed by calculating modified Autoimmune Bullous Skin Disorder Intensity Score (ABSIS) score. Thirty patients with a final diagnosis of bullous pemphigoid were included in the statistical analysis. Pearson's correlation coefficient (r) was used to study correlation.

Results:

The mean ABSIS skin score was 32.81 when both tests were negative, 42.13 when only BP230 was positive, 76.28 when only BP180 was positive, and 78.16 when both were positive. Pearson's correlation coefficient (r) for BP180 and ABSIS skin score was 0.6 (P value: 0.0005), and for BP230 was -0.055 (P value: 0.600).

Conclusions:

BP antibody titers correlate partially with disease severity. Anti-BP180 antibody is associated with more severe disease. Anti-BP230 antibody titer does not correlate with disease severity.

Emerging Biomarkers and Therapeutic Strategies for Refractory Bullous Pemphigoid

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

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.

Recent developments in the pathogenesis of pruritus in bullous pemphigoid

Bullous pemphigoid (BP) is a common autoimmune bullous disease which mainly affects the elderly. The incidence of BP is gradually increasing and associated with high mortality. This disease is clinically characterized by intensely pruritic and widespread bullous lesions. Alternative therapy options for pruritus in patients with BP are limited primarily because pathophysiological mechanisms of itching in BP are still unclear. This review aims to explain crucial concepts of the pathogenesis of pruritus in BP. Vital findings in recent years will be summarized, and cofactors of the pathogenesis of pruritus will be discussed in detail. We will summarize knowledge on pathogenic factors in the immunologic level conducing to skin pruritus in BP.

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).

Presence of Cutaneous Complement Deposition Distinguishes between Immunological and Histological Features of Bullous Pemphigoid-Insights from a Retrospective Cohort Study

The practical implications of complement deposition in direct immunofluorescence (DIF) microscopy and its influence on the disease phenotype are poorly understood. We aimed to investigate whether the presence of complement deposition in DIF microscopy gives rise to differences in the morphological, immunological, and histological characteristics of patients with BP (bullous pemphigoid). We performed a retrospective study encompassing patients with BP in a specialized tertiary referral center. Logistic regression model was utilized to identify variables independently associated with complement deposition. The study included 233 patients with BP, of whom 196 (84.1%) demonstrated linear C3 deposition along the dermal-epidermal junction (DEJ) in DIF analysis. BP patients with C3 deposition had higher mean (SD) levels (645.2 (1418.5) vs. 172.5 (243.9) U/mL; p < 0.001) and seropositivity rate (86.3% vs.64.9%; p = 0.002) of anti-BP180 NC16A and less prevalent neutrophilic infiltrate in lesional skin specimens (29.8% vs. 52.4%; p = 0.041). C3 deposition was found positively associated with the detection of anti-BP180 NC16A autoantibodies (OR, 4.25; 95% CI, 1.38–13.05) and inversely associated with the presence of neutrophils in lesional skin (OR, 3.03; 95% CI, 1.09–8.33). To conclude, complement deposition influences the immunological and histological features of BP. These findings are in line with experimental data describing the pathogenic role of complement in BP.

International validation of the Bullous Pemphigoid Disease Area Index severity score and calculation of cut-off values for defining mild, moderate and severe types of bullous pemphigoid

BACKGROUND

The Bullous Pemphigoid Disease Area Index (BPDAI) score has been proposed to provide an objective measure of bullous pemphigoid (BP) activity.

OBJECTIVES

The objective of this study was to calculate BPDAI cut-off values defining mild, moderate and severe BP. We also aimed to assess the interrater reliability and correlation with the number of daily new blisters, and anti-BP180 and anti-BP230 antibodies.

METHODS

Severity scores were recorded by two blinded investigators. Anti-BP180 and anti-BP230 antibodies were measured using an enzyme-linked immunosorbent assay (ELISA). Cut-off values defining mild, moderate and severe subgroups were calculated based on the 25th and 75th percentiles of the BPDAI score.

RESULTS

In total, 285 patients with BP were enrolled from 50 dermatology departments in Europe. Median BPDAI activity was 37·5 points (range 0-164). Cut-off values corresponding to the first and third quartiles of the BPDAI score were 20 and 57, respectively; thus, these values were used to define mild (≤ 19), moderate (≥ 20 and ≤ 56) and severe (≥ 57) BP. The median BPDAI score for patients with ≤ 10 daily new blisters was 26 [interquartile range (IQR) 17-45], and for patients with > 10 daily new blisters the median score was 55 (IQR 39-82). The BPDAI intraclass correlation coefficient measured at baseline was 0·97 and remained higher than 0·90 up to month 6. The improvement in the BPDAI score was correlated with the absolute decrease in anti-BP180 ELISA value (Spearman's rank r = 0·34, P < 0·004), but not with anti-BP230 antibodies (r = 0·17, P = 0·15).

CONCLUSIONS

This study suggests cut-off values of 20-57 for BPDAI to distinguish mild, moderate and severe BP, and confirms that it is a robust tool to assess BP severity precisely.

IgE autoantibodies in serum and skin of non-bullous and bullous pemphigoid patients

BACKGROUND

Non-bullous pemphigoid (NBP) is a pemphigoid variant which frequently resembles other pruritic skin diseases. In contrast with bullous pemphigoid (BP), blisters are absent. In BP, previous studies showed that IgE autoantibodies may be involved in its pathogenesis. IgE-activated mast cells, basophils and eosinophils may participate in BP by inducing pruritus and possibly blister formation, although the differential role of IgE in NBP compared with BP has not yet been described.

OBJECTIVE

To assess IgE in serum and skin of NBP and BP patients.

METHODS

We examined total IgE and pemphigoid-specific IgE in the serum of 68 NBP and 50 BP patients by enzyme-linked immunosorbent assay (ELISA). Sera of 25 pemphigus patients and 25 elderly patients with pruritus were included as controls. Skin biopsies of 14 NBP and 14 BP patients with the highest IgE titres to NC16A were stained for IgE by immunofluorescence techniques.

RESULTS

Total IgE was elevated in 63% of NBP and 60% of BP patients, and in 20% of pemphigus controls, as well as 60% of elderly controls. IgE ELISAs were more frequently positive in BP than in NBP (NC16A 18% vs. 9%, P = 0.139; BP230 34% vs. 22%, P = 0.149). IgE ELISAs for NC16A and BP230 were positive in 8% and 20% of elderly controls, respectively, while all pemphigus controls were negative. Two of 28 biopsies (7%; one NBP, one BP) showed linear IgE along the basement membrane zone, while in most biopsies (71% NBP; 86% BP) IgE was bound to dermal cells.

CONCLUSION

Since IgE was present in the serum and skin of both NBP and BP patients, this supports IgE-dependent mechanisms common to both diseases, such as pruritus. However, it remains to be elucidated whether IgE contributes to blister formation in BP.

Anti-BP180 autoantibody levels at diagnosis correlate with 1-year mortality rates in patients with bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is the most frequent autoimmune blistering disease mainly affecting elderly patients. Among several published risk factors, a recent post hoc analysis linked anti-BP180 autoantibodies (AABs) to fatal outcomes in BP. To date, this finding has not been confirmed independently.

OBJECTIVE

To investigate the potential of anti-BP180-AAB levels as a marker of prognosis and to identify a cut-off level indicative of an increased risk for early death. Secondly, to characterize parameters associated with mortality.

METHODS

Retrospective, single-centre study of BP patients diagnosed between 2001 and 2012. Analyses included epidemiological and patient- and disease-specific characteristics as well as immunological parameters at diagnosis and during follow-up. Standardized mortality ratios as well as uni- and multivariate regression analyses were calculated.

RESULTS

One hundred patients (56 women, 44 men) with a median age of 81 years (interquartile range 74-86) were followed up for a median of 775 days (interquartile range 162-1617). One-year mortality rates were 25.0% implying a 2.4-fold increased risk of death compared with the general population. High anti-BP180 autoantibody levels at diagnosis (CI₉₅ 1.30-2.89; P = 0.001), dementia (CI₉₅ 1.13-6.72; P =0.03), length of hospitalization (CI₉₅ 1.16-2.41; P = 0.01) and age (CI₉₅ 1.23-4.19; P = 0.009) correlated significantly with 1-year mortality. BP180-AAB concentrations of ≥61 U/mL characterized a subgroup of patients with a particular higher risk for early death compared with the general population (CI₉₅ 1.81-3.81; P < 0.0001).

CONCLUSION

In bullous pemphigoid, serum concentrations of BP180 autoantibodies at diagnosis could help to identify patients at risk for death within the first year after diagnosis (cut-off value 61 U/mL).

Factors associated with the activity and severity of bullous pemphigoid: a review

Bullous pemphigoid (BP) is the most common subepidermal autoimmune blistering disease. It usually affects people older than 70 years of age. The two main autoantigens are BP180 and BP230, both of which are components of hemidesmosomes. Immunoglobulin (Ig)G and IgE autoantibodies to BP180 detected by the enzyme-linked immunoassay (ELISA) show close associations with the activity and severity of BP. In addition, inflammatory cells (eosinophils, neutrophils and mast cells) and cytokines (e.g. interleukins and CC chemokine ligands) play an important part in the pathogenesis, activity and severity of BP. We summarized the potential contribution of each factor postulated to be associated with the activity and severity of BP, and provide guidance for clinicians to pay timely and close attention to such parameters. This review may also promote the development of novel therapies for BP.Key MessagesBullous Pemphigoid Disease Area Index (BPDAI) is a scoring system which can reflect the extent of clinical involvement of BP patients.The titres of IgE autoantibodies and IgG autoantibodies against the NC16A domain of BP180 are closely correlated with the activity and severity of BP.Many inflammatory cells and molecules, such as eosinophils and interleukins, can also reflect the activity and severity of BP.

Correlation of dermal and blood eosinophilia with bullous pemphigoid disease severity

Background

Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease associated with immune response against BP-180 and BP-230. Peripheral blood eosinophilia and dermal infiltration of eosinophils are common findings in BP.

Objective

The aim of our study was to demonstrate a statistical correlation between dermal and peripheral blood eosinophilia, anti BP-180, and anti BP-230 IgG and clinical severity of BP.

Methods

A total of 27 patients with newly diagnosed BP were included. Severity of disease was assessed according to the bullous pemphigoid disease activity index (BPDAI). Anti-BP-180 and anti-BP-230 titers, peripheral blood eosinophilia, and dermal eosinophil infiltration and tissue inflammation severity were assessed for each patient.

Results

A significant correlation was found between the serum levels of anti-BP-180 and anti-BP-230, and dermal eosinophilia and tissue inflammation severity with objective and subjective BPDAI scores. In addition, there was a significant correlation between the percentage of peripheral blood eosinophils and subjective BPDAI scores and urticarial/eczematous lesions. Moreover, the mucosal component did not show any correlation with autoantibody levels and inflammation severities.

Conclusion

Anti-BP-180 and anti-BP-230 levels, tissue inflammation severity, and dermal eosinophilia had a strong and significant correlation with BP severity. In addition, percentage of peripheral blood eosinophilia showed a correlation with subjective BPDAI scores.

The pathogenesis of bullous skin diseases

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

A Cross-Sectional Study Comparing the Prevalence of Bullous Pemphigoid Autoantibodies in 275 Cases of Type II Diabetes Mellitus Treated With or Without Dipeptidyl Peptidase-IV Inhibitors

Background: Anti-hyperglycemic drug dipeptidyl peptidase-IV inhibitors (DPP-4i) have recently been recognized as bullous pemphigoid (BP) inducing drugs. It remains uncertain whether DPP-4i induce BP-IgG autoantibodies before the onset of BP. Objective: To evaluate the effect of DPP-4i in the development of BP-IgG autoantibodies in type 2 diabetes mellitus (T2DM) patients. Methods: A cross-sectional study on 221 DPP-4i (+) and 54 DPP-4i (-) T2DM cases was conducted. BP180 NC16A, BP230, and full-length BP180 ELISAs were used to detect the BP-IgG autoantibodies. We have also statistically analyzed the proportion of age, gender, intake periods of DPP-4i, and hemoglobin A1c level between anti-full-length BP180 IgG-positive and -negative DPP-4i (+) T2DM cases to identify co-founding factors. Results: BP180 NC16A ELISA, BP230 ELISA, and full-length BP180 ELISA were positive in 1.8, 2.2, and 10.9% of DPP-4i (+) T2DM cases, respectively; in contrast, they were positive in 0, 7.4, and 5.6% of DPP-4i (-) T2DM cases, respectively. The odds ratio for the development of BP-IgG autoantibodies detected by full-length BP180 ELISA was 2.070 for DPP-4i (+). There were no significant differences between the genders, intake periods of DPP-4i, nor of hemoglobin A1c levels, the anti-full-length BP180 IgG-positive cases tended to be significantly older than anti-full-length BP180 IgG-negative cases (median 74 vs. 69, p = 0.025) in the DPP-4i (+) T2DM cases. Limitations: We focused the analysis on DPP-4i intake and not on the effects of metformin and other drugs. Conclusion: Exposure to specific DPP-4i may induce the development of anti-full-length BP180 autoantibodies even in T2DM patients without any clinical symptoms of BP. Aging would be a risk factor to develop anti-full-length BP180-IgG autoantibody in DPP-4i (+) T2DM cases.

Normal human skin is superior to monkey oesophagus substrate for detection of circulating BP180-NC16A-specific IgG antibodies in bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering skin disease. Two antigens have been identified as targets of circulating autoantibodies (autoAbs) - BP180 and BP230 - with BP180 being a critical transmembrane adhesion protein of basal keratinocytes of the epidermis. The noncollagenous domain 16A (NC16A) of BP180 is the immunodominant epitope in patients with BP, and anti-BP180-NC16A IgG antibodies (Abs) correlate to disease activity. Routine serological testing and follow-up of BP relies on indirect immunofluorescence (IIF) of serum Abs, commonly performed on monkey oesophagus (ME), and/or enzyme-linked immunosorbent assay (ELISA) testing on recombinantly produced fragments of BP180 and BP230 (BP180-NC16A, BP230-C/N).

OBJECTIVES

To determine if NC16A epitopes are well represented on ME substrate.

METHODS

Sera from different BP cohorts were tested by IIF on ME and normal human skin (NHS). To confirm findings, affinity-purified anti-BP180-NC16A/BP230 polyclonal Abs and recombinant anti-BP180-NC16A/BP230 monoclonal antibodies (mAbs) were used.

RESULTS

For sensitive detection of BP180-NC16A-specific IgG Abs, sections of NHS are superior to the widely used ME. Confirmation comes from polyclonal affinity-purified anti-BP180-NC16A/BP230 Abs, and by mAbs cloned from a patient with active BP.

CONCLUSIONS

Use of NHS is preferable over ME in routine IIF testing for BP. These results are of clinical relevance because anti-BP180-NC16A IgG titres are correlated to disease activity and detecting them reliably is important for screening, diagnosis and follow-up of patients with BP.

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.