Mortality in Patients with Bullous Pemphigoid: A Retrospective Cohort Study, Systematic Review and Meta-analysis

Comorbidity in bullous pemphigoid: up-date and clinical implications

Bullous pemphigoid is the most common autoimmune blistering disease in industrialized countries and particularly affects the elderly. In this patient population, comorbid diseases are frequent and may complicate management and treatment of bullous pemphigoid. A better understanding why distinct diseases are more frequent in bullous pemphigoid patients may lead to new pathophysiological insights and - as a consequence - result in better patient care. The association of bullous pemphigoid with neurological and psychiatric diseases is well known and confirmed by several case-control studies. Association with further diseases such as malignancy and metabolic diseases are still discussed controversially. In recent years new relationships between bullous pemphigoid and autoimmune as well as inflammatory skin diseases have been reported. This review provides a systematic overview on studies addressing comorbidity in bullous pemphigoid patients. Increasing the awareness of both, common and rare comorbid diseases, may enable clinicians to optimize patient support and individualized treatment of bullous pemphigoid.

Analysis of the clinical characteristics of pembrolizumab-induced bullous pemphigoid

Background

Pembrolizumab, a programmed cell death protein 1 checkpoint inhibitor, is a novel drug used to treat a variety of advanced malignancies. However, it can also result in many immune-related adverse events, with cutaneous toxicities being the most frequent. Regarding pembrolizumab-induced skin adverse reactions, bullous pemphigoid (BP) has the worst effects on quality of life. Recently, there have been more and more reports of BP incidents resulting from pembrolizumab therapy in patients with cancer. This study aimed to define the clinical characteristics, diagnosis and management of pembrolizumab-induced BP and identify potential differences between classical BP and pembrolizumab-induced BP.

Methods

Case reports, case series, and case analyses of pembrolizumab-induced BP up to 10 December 2022 were collected for retrospective analysis.

Results

Our study included 47 patients (33 males and 14 females) from 40 studies. The median age was 72 years (range 42-86 years). The median time to cutaneous toxicity was 4 months (range 0.7-28 months), and the median time to bullae formation was 7.35 months (range 0.7-32 months). The most common clinical features were tense bullae and blisters (85.11%), pruritus (72.34%), and erythema (63.83%) on the limbs and trunk. In 20 of the 22 cases tested, the serum anti-BP180 autoantibodies were positive. However, in 10 cases (91.90%, 10/11) the circulating autoantibodies of anti-BP230 were negative. 40 patients had skin biopsies and the skin biopsy revealed subepidermal bullae or blister eosinophil infiltration in 75.00% of patients with pembrolizumab-induced BP, 10.00% of patients with lymphocyte infiltration and 20.00% of patients with neutrophil infiltration. There were 20 patients (50%) with eosinophilic infiltration around the superficial dermis vessels, 8 patients (20.00%) with lymphocyte infiltration around the superficial dermis vessels, and 4 patients (10.00%) with neutrophil infiltration around the superficial dermis vessels. Direct immunofluorescence detected linear immunoglobulin G (IgG) IgG and/or complement C3 along the dermo-epidermal junction in 36 patients (94.74%) with BP. IgG positivity was detected by indirect immunofluorescence in 81.82% of patients with BP. All patients were in complete remission (95.65%,44/46) or partial remission (4.35%, 2/46) of BP, whereas 9/46 patients had a relapse or refractory. The majority of patients achieved BP remission after discontinuation of pembrolizumab with a combination of topically and systemically administered steroid treatments, or other medications. The median duration of BP remission was 2 months (range 0.3-15 months).

Conclusion

A thorough diagnosis of pembrolizumab-induced BP should be made using clinical signs, biochemical markers, histopathological and immunopathological tests. Pembrolizumab-induced BP had similar clinical characteristics to classic BP. Temporary or permanent discontinuation of pembrolizumab therapy may be required in patients with perbolizumab-induced BP depending on the severity of BP and the response to medication. Pembrolizumab-induced BP may be effectively treated using topical and systemic steroid treatments in combination with other medications (e.g., doxycycline, niacinamide, dapsone, rituximab, intravenous immunoglobulins, dupilumab, cyclophosphamide, methotrexate, mycophenolate mofetil, and infliximab). Clinicians should provide better management to patients with BP receiving pembrolizumab to prevent progression and ensure continuous cancer treatment.

Identification of oral immune disorders- A review and a diagnostic algorithm

Immunological disorders are observed in various clinical presentations in the oral cavity. The pathophysiology of these disorders include but are not limited to primary oral auto-immune disease, systemic disease with oral findings, malignancies, hypersensitivity reactions, drug-induced, and infection-related. Many of these disorders have overlapping oral features, making it difficult for the clinician to diagnose and treat the disorder. There is a need to provide a simple and practical decision-making algorithm to the clinicians and provide them guidance on laboratory investigations. The present review provides a diagnostic algorithm that might minimize outpatient process delays and lead to early management. This is crucial in many cases where oral findings may be the first sign of the disorder, and early treatment can preclude dissemination and complications of the disorder.

Blasenbildende Autoimmundermatosen – Klinik, Diagnostik und neue Therapieansätze

Diese Arbeit gibt eine Übersicht über die Gruppe blasenbildender Autoimmundermatosen und stellt deren wichtigste Vertreter, das bullöse Pemphigoid, den Pemphigus vulgaris sowie den Pemphigus foliaceus, vor. Die häufigste der insgesamt seltenen blasenbildenden Autoimmundermatosen ist das bullöse Pemphigoid (BP). Es betrifft vor allem Patienten jenseits des 60. Lebensjahrs. Charakterisiert ist es typischerweise durch das Auftreten praller Blasen, die mit einem heftigen Juckreiz einhergehen. Ein längeres, sogenanntes prämonitorisches Stadium ohne Blasenbildung ist nicht ungewöhnlich. Es gibt außerdem Varianten mit anderem Erscheinungsbild wie das lokalisierte BP. Der diagnostische Goldstandard ist die direkte Immunfluoreszenzmikroskopie einer periläsional entnommenen Hautbiopsie, welche lineare Ablagerungen von IgG und C3 an der Basalmembran zeigt. Vervollständigt wird die Diagnostik durch die indirekte Immunfluoreszenzmikroskopie sowie weiterführende ELISA-Untersuchungen, mittels derer zirkulierende Autoantikörper im Patientenserum nachgewiesen werden können. Das wichtigste Zielantigen ist BP180, ein hemidesmosomales, von Keratinozyten exprimiertes Protein. Ergänzend kann eine histopathologische Untersuchung erfolgen, die allerdings nur Hinweise zur Spaltebene und zum (meist Eosinophilen-dominierten) Infiltratmuster geben kann und alleine nicht zur Diagnosestellung ausreicht. Die Pathogenese des BP ist Gegenstand der wissenschaftlichen Diskussion. Medikamente wie Dipeptidylpeptidase-4-Inhibitoren können Auslöser sein; Assoziationen zu neurologischen Erkrankungen finden sich häufig. Entsprechend aktueller Leitlinien wird das BP mit topischen bzw. systemischen Glukokortikoiden ggf. in Kombination mit Doxyzyklin, Dapson oder einem Immunsuppressivum behandelt. Bei Therapieresistenz werden intravenöse Immunglobuline oder der anti-CD-20-Antikörper Rituximab eingesetzt. Aufgrund einer vergleichsweise hohen Mortalität bedingt durch Patientenalter und iatrogener Immunsuppression werden neue Therapieansätze gesucht. Fallserien, Kohortenanalysen und Phase 1-/2-Studien mit anti-IgE-Antikörpern und Inhibitoren der eosinophilen Granulozyten sowie des Komplementsystems zeigen teils vielversprechende Effekte. Die wichtigsten Vertreter der Pemphiguserkrankungen sind der Pemphigus vulgaris (PV), der Pemphigus foliaceus (PF) und der sehr seltene paraneoplastische Pemphigus (PNP). Klinisch präsentiert sich der PV mit meist enoralen Schleimhauterosionen und teilweise zusätzlichen Erosionen an der freien Haut. Der PF manifestiert sich nur an der freien Haut. Wie beim BP wird die Diagnose mittels direkter Immunfluoreszenzmikroskopie gestellt, welche beim PV und PF netzförmige Ablagerungen von IgG und C3 innerhalb der Epidermis zeigt. Die häufigsten Zielantigene sind die Desmogleine 1 und 3. Genetische Prädispositionen für den PV und PF sind bekannt und Grund für eine global unterschiedliche Häufigkeit. Der PNP ist immer mit einer malignen Erkrankung assoziiert und von einem progredienten Verlauf mit hoher Mortalität geprägt. Therapeutisch erfordern die Pemphiguserkankungen oft aggressivere Ansätze als das BP. Neben systemischen Glukokortikoiden und Immunsuppressiva wird für den PV und PF der anti-CD-20-Antikörper Rituximab empfohlen. Neue Therapieansätze sind die Hemmung der Bruton-Tyrosinkinase sowie des neonatalen Fc-Rezeptors (FcRN). In einer Phase 2-Studie zeigte Efgartigimod, ein Antagonist des FcRN, eine hohe Therapieeffektivität für Patienten mit PV und PF.

Successful Treatment of Bullous Pemphigoid Lesions by Berberine Stamp Therapy: A Case Report and Literature Review

Bullous pemphigoid (BP) is a life-threatening autoimmune disease of the skin that is mainly characterized by a large range of tension blisters and intense itching of the skin. The 1-year mortality rate of BP was 23.5%. Superinfection caused by skin lesion ulceration is one of the important causes of disease death. Therefore, it is challenging to control infection and improve skin wound healing. Here, we report the case of an elderly woman who presented with BP and involved the oral mucosa. The patient was successfully treated with hormones combined with topical berberine, and 95% of the patients’ lesions healed completely after 1 month. In addition, we inductively analyzed the current treatments for BP to provide a reference for BP clinical treatment.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prognostic factors for mortality in bullous pemphigoid: A systematic review and meta-analysis

Objective

To systematically evaluate the prognostic factors for mortality in bullous pemphigoid.

Methods

PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine disc and Wanfang Database were searched to collect literature on the prognostic factors for mortality in bullous pemphigoid. The quality of studies was assessed by Newcastle–Ottawa Quality Assessment Scale. Two researchers extracted relevant data and scored study quality independently. The hazard ratio (HR) was calculated using the random effects model. Study heterogeneity was assessed using both Cochran’s Q test and I² statistics. The causes of heterogeneity were assessed by subgroup analysis and/ or sensitivity analysis when heterogeneity was significant. When ten or more studies were included as outcome indicators, publication bias was evaluated by funnel plot and Egger’s test.

Results

Out of a total of 1,546 articles retrieved, 15 studies involving 2,435 patients were included. The meta-analysis showed that the mortality of patients with bullous pemphigoid increased with positive bullous pemphigoid 180 antibody (HR = 1.85, 95%CI: 1.25~2.75, P = 0.002); concomitant dementia (HR = 2.26, 95%CI: 1.43~3.59, P<0.001); stroke (HR = 2.09, 95% CI: 1.23–3.55, P = 0.007); heart disease (HR = 1.96, 95% CI: 1.41–2.73, P<0.001) and diabetes mellitus (HR = 2.39, 95% CI: 1.55–3.69, P<0.001). Sex, positive indirect immunofluorescence and hypertension were not associated with prognosis.

Conclusion

Positive bullous pemphigoid 180 antibody, dementia, stroke, heart disease and diabetes mellitus were the prognostic factors for mortality in bullous pemphigoid.

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.

Association of Immunosuppressants with Mortality of Patients with Bullous Pemphigoid: A Nationwide Population-Based Cohort Study

BACKGROUND

Bullous pemphigoid (BP) is a common autoimmune blistering skin disease with substantial mortality.

OBJECTIVE

To identify whether the use of immunosuppressants was associated with reduced mortality in BP patients.

METHODS

The data for this study were obtained from the National Health Insurance Research Database in Taiwan from January 1, 1997 to December 31, 2013. Those BP patients receiving any immunosuppressant for ≥28 days per month for 3 consecutive months were defined as the immunosuppressant cohort. In total, 452 BP patients on immunosuppressants were matched 1:4 by age, sex, propensity score of comorbidities, and use of tetracycline with 1,808 BP patients taking only corticosteroids.

RESULTS

The immunosuppressant cohort had a significantly lower 5-year mortality rate than the corticosteroid cohort (0.57 vs. 0.67). In the multivariable regression analysis adjusted for covariates, the use of immunosuppressants significantly reduced the risk of mortality (hazard ratio [HR]: 0.78, 95% confidence interval [CI]: 0.68-0.90, p < 0.001). Hyperlipidemia also reduced risk of mortality. However, age, diabetes, renal disease, chronic obstructive pulmonary disease, cerebrovascular disease, and dementia were significant risk factors for mortality. In the subgroup analysis, the risk of mortality decreased most substantially in those aged <70 years (HR: 0.45, 95% CI: 0.28-0.72).

CONCLUSION

Immunosuppressant use was associated with a 22% reduced risk of BP mortality. The effects were more substantial in those aged <70 years, with a 55% reduced risk of mortality.

Bullous Pemphigoid After Total Knee Arthroplasty

Total knee arthroplasty is one of the safest and most routinely performed orthopedic procedures. As the volume of cases is expected to rise each year, so too will the incidence of uncommon complications. We describe a rare case of bullous pemphigoid, an autoimmune skin blistering disorder, that occurred after total knee arthroplasty in an otherwise healthy patient and led to hospital readmission. Early diagnosis and treatment of this condition may limit its spread and help to avoid comorbid sequelae.

The risk of COVID-19 in patients with bullous pemphigoid and pemphigus: A population-based cohort study

Background

The burden of COVID-19 in patients with bullous pemphigoid (BP) and pemphigus is yet to be evaluated.

Objective

To assess the risks of COVID-19 and COVID-19-associated hospitalization and mortality in patients with BP and pemphigus and to delineate determinants of severe COVID-19 illness among these patients.

Methods

A population-based cohort study compared COVID-19 and its complications in patients with BP (n = 1845) and pemphigus (n = 1236) with age-, sex-, and ethnicity-matched control subjects.

Results

The risks of COVID-19 (hazard rate [HR], 1.12; 95% confidence interval [CI], 0.72-1.73; P = .691) and COVID-19-associated hospitalization (HR, 1.58; 95% CI, 0.84-2.98; P = .160) was comparable between patients with BP and controls. The risk of COVID-19-associated mortality was higher among patients with BP (HR, 2.82; 95% CI, 1.15-6.92; P = .023). The risk of COVID-19 (HR, 0.81; 95% CI, 0.44-1.49; P = .496), COVID-19-associated hospitalization (HR, 1.41; 95% CI, 0.53-3.76; P = .499), and COVID-19-associated mortality (HR, 1.33; 95% CI, 0.15-11.92; P = .789) was similar in patients with pemphigus and their controls. Systemic corticosteroids and immunosuppressants did not predispose COVID-19-positive BP and pemphigus patients to a more severe illness.

Limitations

Retrospective data collection.

Conclusions

Patients with BP experience increased COVID-19-associated mortality and should be monitored closely. Maintaining systemic corticosteroids and immunosuppressive adjuvant agents during the pandemic is not associated with worse outcomes.

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.

The Bidirectional Association Between Bullous Pemphigoid and Psoriasis: A Population-Based Cohort Study

The risk of developing psoriasis during the course of bullous pemphigoid (BP) is yet to be investigated. We aimed to assess the risk of psoriasis among patients with BP and the risk of BP in individuals with a history of psoriasis. A population-based retrospective cohort study was conducted comparing BP patients (n = 3,924) with age-, sex-, and ethnicity-matched control subjects (n = 19,280) with regard to incident cases of psoriasis. A case-control design was additionally followed to estimate the risk of BP in those with a preceding diagnosis of psoriasis. Adjusted hazard ratios (HRs) and adjusted odds ratios (ORs) were estimated by Cox regression and logistic regression, respectively. The incidence of psoriasis was 1.78 (95% CI, 1.25–2.48) and 0.67 (95%CI, 0.53–0.83) per 1,000 person-years among patients with BP and controls, respectively. Patients with BP were 2.6-fold more likely to develop psoriasis (HR, 2.60; 95%CI, 1.59–4.27) compared to controls. Furthermore, the prevalence of preexisting psoriasis was higher in patients with BP than in control subjects (1.7 vs. 1.1%, respectively; P < 0.001). A history of psoriasis was associated with a 50% increase in the risk of BP (OR, 1.53; 95%CI, 1.17–2.02). Patients with a dual diagnosis of BP and psoriasis were younger, had higher prevalence of smoking and hypertension, and were treated more frequently with prolonged systemic and topical corticosteroids when compared to the remaining patients with BP. To conclude, a bidirectional association exists between BP and psoriasis. Awareness of this association may be of great importance for physicians managing patients with BP and psoriasis.

Psychiatric comorbidity in individuals with bullous pemphigoid and all bullous disorders in the Danish national registers

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune blistering skin disease that takes a profound physical and mental toll on those affected. The aim of the study was to investigate the bidirectional association between BP and all bullous disorders (ABD) with a broad array of psychiatric disorders, exploring the influence of prescribed medications.

METHODS

This nationwide, register-based cohort study encompassed 6,470,450 individuals born in Denmark and alive from 1994 to 2016. The hazard ratios (HRs) of a subsequent psychiatric disorder in patients with BP/ABD and the reverse exposure and outcome were evaluated.

RESULTS

Several psychiatric disorders were associated with increased risk of subsequent BP (4.18-fold for intellectual disorders, 2.32-fold for substance use disorders, 2.01-fold for schizophrenia and personality disorders, 1.92-1.85-1.49-fold increased risk for organic disorders, neurotic and mood disorders), independent of psychiatric medications. The association between BP and subsequent psychiatric disorders was not significant after adjusting for BP medications, except for organic disorders (HR 1.27, CI 1.04-1.54). Similar results emerged with ABD.

CONCLUSION

Psychiatric disorders increase the risk of a subsequent diagnosis of BP/ABD independent of medications, whereas medications used for the treatment of BP/ABD appear to account for the subsequent onset of psychiatric disorders. Clinically, an integrated approach attending to both dermatological and psychiatric symptoms is recommended, and dermatologists should remain vigilant for early symptoms of psychiatric disorders to decrease mental health comorbidity.

Dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid, likely triggered by scabies, in a hemodialysis patient with human leukocyte antigen-DQB1*03:01

Bullous pemphigoid (BP) is the most common autoimmune subepidermal bullous diseases. Autoantibodies against hemidesmosomal adhesion proteins might be involved in the developing process. BP usually affects the elderly with high mortality whereas the drug-induced BP is often improved and rarely relapses after the withdrawal of the suspected drug. An accumulated evidence suggests that dipeptidyl peptidase-4 inhibitor (DPP-4I), which has been widely used as the antidiabetic drug improves glycemic control with little risk for hypoglycemia, could be an inducer of DPP-4I-associated BP (DPP-4I-BP). While the precise mechanism remains unclear, a unique immunological profile with human leukocyte antigen (HLA)-DQB1*03:01 could be a biomarker of genetic susceptibility to DPP-4I-BP. Here, we encountered an interesting case of DPP-4I-BP with HLA-DQB1*03:01, which was likely triggered by scabies. A 56-year-old Japanese male with type 2 diabetes on hemodialysis was referred to our hospital due to worsened blisters. Prior to his admission, he had been on linagliptin, a DPP-4I, for 5 months. He then suffered from scabies 2 weeks before his admission while the treatment with ivermectin failed to improve his symptom. Based on his clinical symptom, positive for anti-BP180 autoantibody in serum, and the pathological alterations of skin biopsy specimens, he was diagnosed with DPP-4I-BP. Importantly, he also carried an HLA-DQB1*03:01 allele. Oral prednisolone was subsequently administered after the discontinuation of linagliptin, and his symptom gradually disappeared. Given the fact that the DPP-4I-BP could be a life-threating disease, we should be cautious of prescribing DPP-4I in hemodialysis patients, whose immune system could be impaired.

Coagulation and Skin Autoimmunity

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

Dipeptidyl Peptidase-4 Inhibitor-Associated Bullous Pemphigoid

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

Bullous pemphigoid

Bullous pemphigoid is the most frequent autoimmune bullous disease and mainly affects elderly individuals. Increase in incidence rates in the past decades has been attributed to population aging, drug-induced cases and improvement in the diagnosis of the nonbullous presentations of the disease. A dysregulated T cell immune response and synthesis of IgG and IgE autoantibodies against hemidesmosomal proteins (BP180 and BP230) lead to neutrophil chemotaxis and degradation of the basement membrane zone. Bullous pemphigoid classically manifests with tense blisters over urticarial plaques on the trunk and extremities accompanied by intense pruritus. Mucosal involvement is rarely reported. Diagnosis relies on (1) the histopathological evaluation demonstrating eosinophilic spongiosis or a subepidermal detachment with eosinophils; (2) the detection of IgG and/or C3 deposition at the basement membrane zone using direct or indirect immunofluorescence assays; and (3) quantification of circulating autoantibodies against BP180 and/or BP230 using ELISA. Bullous pemphigoid is often associated with multiple comorbidities in elderly individuals, especially neurological disorders and increased thrombotic risk, reaching a 1-year mortality rate of 23%. Treatment has to be tailored according to the patient's clinical conditions and disease severity. High potency topical steroids and systemic steroids are the current mainstay of therapy. Recent randomized controlled studies have demonstrated the benefit and safety of adjuvant treatment with doxycycline, dapsone and immunosuppressants aiming a reduction in the cumulative steroid dose and mortality.