Drug-induced pemphigoid: a review of the literature

Lymphocyte Transformation Tests and Patch Tests to Identify Drugs Potentially Associated With Bullous Pemphigoid Development

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune blistering disease, with a rising incidence in the elderly. BP is associated with multiple triggering factors, including drug exposure. However, evidence in this respect is limited, and the underlying immune mechanisms remain unknown. Our study aims to identify the role of specific drugs in BP pathogenesis using in vitro lymphocyte transformation tests (LTT) and in vivo patch testing, aiding in the differentiation between truly associated drugs and coincidental associations.

METHODS

Thirty-three patients with suspected BP and no ongoing systemic treatment were enrolled. LTT and patch tests were conducted 3 months after diagnosis. BP disease activity was assessed using the Bullous Pemphigoid Disease Activity Index (BPDAI) at diagnosis and at follow-up visits at 3 and 6 months.

RESULTS

LTT results were positive in 60% of patients for dipeptidyl peptidase 4 inhibitors, loop diuretics, hydrochlorothiazide, levetiracetam, nivolumab, enalapril, and amlodipine. Patients showed a reduction in BPDAI over the study period, regardless of LTT results. Although limited by the low sample size, positive LTT patients showed a trend toward clinical improvement when the implicated drug was discontinued. Patch testing was positive in one patient, who also had a corresponding positive LTT.

CONCLUSIONS

Our findings demonstrate the existence of a potential role for certain drugs in BP pathogenesis, suggesting that these drugs may trigger the disease in genetically predisposed individuals. Although further studies are needed, LTT may serve as a useful and available tool in the management of BP patients in the future.

Remote presentation of nivolumab-induced bullous pemphigoid in hepatocellular carcinoma

A man in his 70s with a history of unresectable hepatocellular carcinoma (HCC) treated with nivolumab presented with a blistering rash 14 months after nivolumab initiation. Biopsies and direct immunofluorescence confirmed the diagnosis of bullous pemphigoid (BP). BP is an autoimmune skin disorder in which autoantibodies bind to the dermal-epidermal junction. It is a rare sequela of programmed cell death protein-1 (PD-1) inhibitors that can develop after treatment initiation and typically resolve soon after discontinuation. Most cases are reported in melanoma and non-small cell lung cancers, and rarely in HCC irrespective of the timing of onset. We describe a rare presentation of remote BP with PD-1 inhibitor use in HCC. PD-1 inhibitor-induced BP is a rare cutaneous immune-related adverse event, and this case highlights the variability in onset and chronicity.

A systematic review of the role of interleukin-17 inhibitors in bullous pemphigoid: therapeutic and paradoxical effects

Bullous pemphigoid (BP) is the most common autoimmune-driven blistering disease. The incidence of BP has been rising due to population aging and exposure to medications such as biologics. Moreover, biologics are utilized as therapeutic choices for BP treatment as they inhibit cytokines and disrupt pathogenesis pathways. Secukinumab and ixekizumab are two biologics that block interleukin (IL)-17A cytokines, a crucial factor in the autoimmune inflammatory pathway. We aim to systematically evaluate the effect of IL-17 inhibitors on treating and triggering BP disease. A systematic search was carried out up to Sept 16, 2023, in PubMed/Medline, Ovid-Embase, Scopus, and Web of Science. Clinical studies published in English were included. The search identified 282 relevant records, and ten articles were included. Moreover, one clinical trial was found through a search on Clinicaltrial.gov. Secukinumab and ixekizumab significantly improve BP lesions and blisters in combination with prednisolone or alone in BP subjects with or without concomitant psoriasis. However, ixekizumab has failed in a recent clinical trial. In contrast, BP has developed in some patients who were treated with these drugs for an underlying condition. IL-17 inhibitors exert both beneficial and paradoxical effects on BP. Further investigations are warranted to better understand the effects of these agents on BP.

The "entanglement" between bullous pemphigoid and diabetes mellitus: a comprehensive review and expert recommendations

INTRODUCTION

Bullous pemphigoid (BP) is an autoimmune bullous disease characterized by subepidermal tense blisters, accompanied by urticarial or eczema-like lesions. Circulating autoantibodies in BP patients target BP180 and BP230 at the dermal-epidermal junction. There has been a growing interest in unraveling the intricate relationship between BP and diabetes mellitus (DM), but a comprehensive review is lacking.

AREAS COVERED

A thorough search of PubMed was conducted to identify studies concerning the association between BP and DM (1978-2023). Our findings comprehensively summarize the intricate association between BP and DM, focusing on the characteristics, potential pathomechanisms, and the influence of various antidiabetic medications on BP development.

EXPERT OPINION

DM emerges as a prevalent comorbidity and potential risk factor for BP. New-onset DM can manifest during BP treatment, primarily due to corticosteroid therapy. Among all antidiabetic medications, dipeptidyl peptidase-IV inhibitors (DPP-4i) have the most solid association with BP onset. Other antidiabetic medications have also been reportedly associated with BP, including meglitinides, glucagon-like peptide 1 (GLP-1)-receptor agonists, and sodium-dependent glucose transporters 2 inhibitors (SGLT-2i). We suggest prescribing DPP-4i in caution for elderly DM patients with a history of autoimmune diseases.

Association between drugs and vaccines commonly prescribed to older people and bullous pemphigoid: a case-control study

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune skin disease that mainly affects older people. Based on case series and small hospital-based studies, a number of drugs have been associated with BP. More reliable and precise estimates of associations between a broad selection of drugs/vaccines and BP will enable greater awareness of any potential increased risk of BP following the administration of certain medicines and help identify clinical, histological and genomic characteristics of drug-induced BP for different culprit drugs. Greater awareness could lead to earlier recognition or suspicion of BP and referral to a dermatologist for diagnosis. Earlier diagnosis may lead to less aggressive treatment and improved wellbeing.

OBJECTIVES

To determine the association between drugs/vaccines commonly prescribed to older people and the risk of developing BP.

METHODS

We conducted a population-based nested case-control study between 1998 and 2021 using electronic primary care records from the Clinical Practice Research Datalink. We matched patients with BP with up to five controls. Exposures were drugs/vaccines commonly prescribed to older people. We used multivariable conditional logistic regression adjusting for multiple drug use. For antibiotics, in a sensitivity analysis, we considered that drugs may be prescribed for undiagnosed symptoms of BP that resemble skin infection (protopathic bias).

RESULTS

Antibiotics were associated with the highest risk of BP [odds ratio (OR) 4.60, 95% confidence interval (CI) 4.40-4.80]. However, after adjusting for protopathic bias, the OR decreased to 2.08 (95% CI 1.99-2.17). Also, after adjusting for protopathic bias, of all the antibiotic classes and subclasses, penicillins [OR 3.44, 95% CI 3.29-3.60 (sensitivity analysis OR 1.74, 95% CI 1.66-1.84)] and penicillinase-resistant penicillins [OR 7.56, 95% CI 7.15-8.00 (sensitivity analysis OR 2.64, 95% CI 2.45-2.85)] had the strongest associations with BP risk. Other drugs strongly associated with increased risk were gliptins (OR 2.77, 95% CI 2.37-3.23) and second-generation antipsychotics (OR 2.58, 95% CI 2.20-3.03).

CONCLUSIONS

Healthcare professionals need to be aware of BP risk in older people, particularly when prescribing penicillinase-resistant penicillins, gliptins and second-generation antipsychotic drugs, to recognize and manage BP early. Owing to the low disease prevalence, we do not suggest avoiding certain drugs/vaccines to prevent BP. Further research should consider recency, dosage and duration of antibiotic treatments.

From Pruritus to Bullae: Recognizing Furosemide-Induced Bullous Pemphigoid in an Elderly Male Patient

Bullous pemphigoid (BP) is an autoimmune blistering disorder characterized by tense bullae and severe generalized pruritus. However, atypical presentations in elderly patients may involve localized pruritus prior to the development of bullae, which can obscure the diagnosis and delay appropriate treatment. We present a case of BP induced by furosemide in an 83-year-old male patient with congestive heart failure. The patient initially experienced persistent pruritus on the bilateral arms and back, which emerged approximately three months after initiating furosemide therapy. This pruritus was initially attributed to xerosis. Subsequently, erythematous papules developed in these areas, raising suspicion for atypical scabies, although they did not respond to permethrin treatment. A shave biopsy revealed subepidermal bullous disease with numerous eosinophils, and direct immunofluorescence confirmed the diagnosis of BP, showing linear IgG and granular C3 deposition at the basement membrane zone. The papules then evolved into tense bullae, and serologic testing supported the diagnosis with elevated IgG titers and positive BP180 antibodies. Furosemide was discontinued as the likely trigger. Initial treatment with prednisone led to improvement; however, bullae reappeared upon tapering the medication. Further management with doxycycline and topical triamcinolone resulted in enhanced improvement. Ultimately, biweekly dupilumab injections effectively controlled the symptoms. This case underscores the diagnostic challenges of BP, particularly in the elderly, where isolated pruritus may precede the appearance of visible bullous lesions. Clinicians should maintain a high index of suspicion for BP in elderly patients with unexplained pruritus, especially when standard treatments are ineffective. Additionally, this case highlights the importance of considering drug-induced BP, with furosemide recognized as a potential trigger.

Drug associated bullous pemphigoid: what's new?

Bullous pemphigoid (BP) is considered to be one of the most common autoimmune diseases affecting the skin. Drug associated BP (DABP) is a subset of BP that is caused by the ingestion of specific types of medications. Until this point more than 80 medications have been associated with this condition that only recently has started to be better described. DABP has a better clinical course and prognosis compared to that of idiopathic BP, especially when the suspected inciting medication is discontinued in a timely manner. Therefore, it is very important to obtain detailed medical histories from BP patients especially if they are receiving multiple medications and also to be vigilant for subtle, but important, indications in histopathological, ELISA and immunofluorescence findings as well as in the clinical manifestations of the disorder.

Esophageal involvement in Bullous pemphigoid: Case report

Bullous pemphigoid is a rare chronic autoimmune dermatologic blistering disease that usually affects elderly patients. Mucosal lesions are present in about 10%-35% of cases and affects most frequently the mucous membranes of the eye or the mouth. Esophageal involvement is possible but is rare (4% of cases). It could be asymptomatic, or presents with dysphagia, odynophagia, chest pain, or upper gastro-intestinal bleeding. We report the case of a recently diagnosed bullous pemphigoid in a 73-years-old female with normochromic normocytic anemia due to vitamin B12 deficiency who was referred to our unity for esophagogastroduodenoscopy. Our endoscopic examination revealed two bullae filled with blood at upper esophagus with linear ulcerations and membrane detachment upon withdrawal of the endoscope. Although bullous pemphigoid is mainly a skin disease, invasion of esophagus needs to be considered especially when symptoms are present or when no cause was found for blood loss or anemia.

Drugs and the skin: A concise review of cutaneous adverse drug reactions

Drug-induced skin disease or cutaneous adverse drug reactions (CADRs) are terms that encompass the clinical manifestations of the skin, mucosae and adnexa induced by a drug or its metabolites. The skin is the organ most frequently affected by drug reactions, which may affect up to 10% of hospitalized patients and occur in 1-3% of multimedicated patients. Most CADRs are mild or self-resolving conditions; however, 2-6.7% of could develop into potentially life-threatening conditions. CADRs represent a heterogeneous field and can be diagnostically challenging as they may potentially mimic any dermatosis. Currently, there are between 29-35 different cutaneous drug-reaction patterns reported ranging from mild dermatitis to an extensively burnt patient. The most frequently reported are maculopapular rash, urticaria/angioedema, fixed drug eruption and erythema multiforme. Less common but more severe patterns include erythroderma, drug reaction with eosinophilia and systemic symptoms, and Stevens-Johnson syndrome/toxic epidermal necrolysis spectrum. Almost any drug can induce a CADR, but antibiotics, nonsteroidal anti-inflammatory drugs and antiepileptics are the most frequently involved. Different mechanisms are involved in the pathogenesis of CADRs, although in some cases, these remain still unknown. CADRs could be classified in different ways: (i) type A (augmented) or type B (bizarre); (ii) immediate or delayed; (iii) immune-mediated or nonimmune-mediated; (iv) nonsevere or life-threatening; and (v) by their phenotype, including exanthematous, urticarial, pustular and blistering morphology. Recognizing a specific CADR will mostly depend on the ability of the physician to perform a detailed clinical examination, the proper description of the morphology of the skin lesions and supporting laboratory and/or skin biopsy findings.

Cutaneous adverse effects of antiepileptic drugs

Antiepileptic drugs (AED) are widely used in therapy. They are mainly indicated in the treatment of epilepsy and some psychiatric pathologies as well as for their analgesic action. Their cutaneous adverse effects (CAE) are common, often mild but sometimes serious. The aim of this work was to study the epidemiological and clinical features of CAE occurring in adults and elderly patients (aged over 20 years-old) and to identify the most implicated AED. We conducted a descriptive retrospective study over a period of five years from January 2017 to December 2022 about CAE of AED in adults and elderly patients notified to The National Center Chalbi Belkahia of Pharmacovigilance (Tunis,Tunisia). All cases were analyzed according to the updates French methods of imputability. We collected 71 cases of patients aged over 20 years old who presented CAE to AED. The age ranged from 20 to 79 years (mean age=44.8 years). The sex ratio F/M was 0.7. AED were indicated for neurological pathology in 70.5% of cases, for psychiatric pathology in 15.9% of cases and for their analgesic action in 12.9% of cases. Epilepsy was the first indication (51.1% of cases). The most notified CAE in our study were drug reaction with eosinophilia and systemic symptoms (DRESS syndrome; 34% of cases), maculopapular exanthema (MPE; 26% of cases), erythematous rash (8% of cases) and photosensitivity in 5% of cases. Severe cutaneous adverse reactions were accounted for 37% of all CAE. The most implicated AED were carbamazepine (52%), phenobarbital (24%) and lamotrigine (18%). However, further study with a larger number of patients and in collaboration with prescribing physicians are needed to better clarify features of CAE associated with AED intake and specify the risk factors, specific to our Tunisian population.

Identification of Risk Factors for Gliptin-associated Bullous Pemphigoid among Diabetic Patients

Drug-associated bullous pemphigoid has been shown to follow long-term gliptin (dipeptidyl-peptidase 4 inhibitors) intake. This study aimed at identifying risk factors for gliptin-associated bullous pemphigoid among patients with type 2 diabetes. A retrospective study was conducted in a tertiary centre among diabetic patients exposed to gliptins between the years 2008-2021. Data including demographics, comorbidities, medications, and laboratory results were collected using the MDClone platform. Seventy-six patients with type 2 diabetes treated with dipeptidyl-peptidase 4 inhibitors who subsequently developed bullous pemphigoid were compared with a cohort of 8,060 diabetic patients exposed to dipeptidyl-peptidase 4 inhibitors who did not develop bullous pemphigoid. Based on a multivariable analysis adjusted for age and other covariates, Alzheimer's disease and other dementias were significantly more prevalent in patients with bullous pemphigoid (p = 0.0013). Concomitant use of either thiazide or loop diuretics and gliptin therapy was associated with drug-associated bullous pemphigoid (p < 0.0001 for both). While compared with sitagliptin, exposure to linagliptin and vildagliptin were associated with bullous pemphigoid with an odds ratio of 5.68 and 6.61 (p < 0.0001 for both), respectively. These results suggest gliptins should be prescribed with caution to patients with type 2 diabetes with coexisting Alzheimer's and other dementias, or patients receiving long-term use of thiazides and loop diuretics. The use of sitagliptin over linagliptin and vildagliptin should be preferred in these patients.

A Novel Strategy for the Discovery of Drug Targets: Integrating Clinical Evidence with Molecular Studies

The mechanisms of several drugs remain unclear, limiting our understanding of how they exert their effects. Receptor affinities have not been comprehensively measured during drug development, and the safety investigations in humans are limited. Therefore, numerous unknown adverse and beneficial effects of drugs in humans persist. In this review, I highlight our achievements in identifying the unexpected beneficial effects of drugs through the analysis of real-world clinical data, which can contribute to drug repositioning and target finding. (1) Through the analysis of real-world data, we found that the anti-arrhythmic amiodarone induced interstitial lung disease, leading to fibrosis. Surprisingly, concurrent use of an anti-thrombin drug, dabigatran mitigated these adverse events. Pharmacological studies using animal models have mimicked this phenomenon and revealed the molecular mechanisms associated with the platelet-derived growth factor-alpha receptors. (2) The antidiabetic dipeptidyl-peptidase 4 inhibitors increased the risk of an autoimmune disease, bullous pemphigoid, which was reduced by the concomitant use of lisinopril. Pharmacological studies using human peripheral blood mononuclear cells have revealed that lisinopril suppressed the skin disorders by inhibiting the expression of cutaneous matrix metalloproteinase 9 in macrophages. (3) The antimicrobial fluoroquinolones increased the risk of tendinopathy, which was reduced by the concomitant use of dexamethasone. However, clinical guidelines have suggested that corticosteroid increases the risk of tendinopathy. Our investigation demonstrated that fluoroquinolones impaired tendon cells through DNA damage by generating reactive oxygen species. In contrast, dexamethasone exhibited an acute beneficial effect on tendon tissue by upregulating the expression of a radical scavenger, glutathione peroxidase 3.

From Molecular Insights to Clinical Perspectives in Drug-Associated Bullous Pemphigoid

Bullous pemphigoid (BP), the most common autoimmune blistering disease, is characterized by the presence of autoantibodies targeting BP180 and BP230 in the basement membrane zone. This leads to the activation of complement-dependent and independent pathways, resulting in proteolytic cleavage at the dermoepidermal junction and an eosinophilic inflammatory response. While numerous drugs have been associated with BP in the literature, causality and pathogenic mechanisms remain elusive in most cases. Dipeptidyl peptidase 4 inhibitors (DPP4i), in particular, are the most frequently reported drugs related to BP and, therefore, have been extensively investigated. They can potentially trigger BP through the impaired proteolytic degradation of BP180, combined with immune dysregulation. DPP4i-associated BP can be categorized into true drug-induced BP and drug-triggered BP, with the latter resembling classic BP. Antineoplastic immunotherapy is increasingly associated with BP, with both B and T cells involved. Other drugs, including biologics, diuretics and cardiovascular and neuropsychiatric agents, present weaker evidence and poorly understood pathogenic mechanisms. Further research is needed due to the growing incidence of BP and the increasing identification of new potential triggers.

Prevalence of diabetes mellitus in bullous pemphigoid patients in the absence of dipeptidyl peptidase-4 inhibitors: a systematic review and meta-analysis

Bullous pemphigoid (BP) has been associated with dipeptidyl peptidase-4 inhibitor (DDP-4i) use in patients with diabetes mellitus (DM). The prevalence and association of DM in BP patients independent of DPP-4i use has not been investigated by meta-analysis. To perform a systematic review and meta-analysis on the association between diabetes and bullous pemphigoid. The goal was to determine the prevalence and pooled odds ratio of BP patients with DM in the absence of DDP-4i use compared to the general population prevalence of diabetes mellitus. OVID Medline, EMBASE, Cochrane Central and Web of Science were searched for relevant studies published from inception to April 2020. Case-control, case-series, cohort, and cross-sectional studies that included the association of BP and DM without DDP-4i's, in any language. PRISMA guidelines were followed for data extraction and the Newcastle-Ottawa Scale for risk of bias evaluation. Three reviewers independently performed data extraction. Pooled odds ratio and prevalence were calculated using the random effects model. The odds ratio and prevalence of BP patients with DM. Overall, 8 studies out of 856 identified publications through data base searches were included. The pooled prevalence of diabetes in patients with BP was 20.0% [95% CI 14%-26%; p = 0.00]. Within the comparative non-BP control population, 13% had diabetes. BP patients were more likely to have diabetes compared to a control population without BP [OR 2.10, 95% CI 1.22-3.60; p = 0.01]. This study found that twice the number of BP patients have DM (20%) compared to the general population reported as 10.5%, warranting monitoring of blood glucose levels in BP patients who may have yet undeclared or undiagnosed DM when initiating systemic steroids.

The effect of dipeptidyl peptidase-4 inhibitor on incidence and clinical course in bullous pemphigoid patients in a tertiary medical center

Several studies have reported an association between dipeptidyl peptidase 4 inhibitor (DPP4i), a commonly prescribed second-line oral antihyperglycemic drug, and bullous pemphigoid (BP). However, the benefits of DPP4i withdrawal in patients with BP remain controversial. This study primarily aimed to evaluate the clinical severity of DPP4i-associated BP by comparing it to those without Type 2 diabetes mellitus (DM). The secondary objective was to determine whether cessation of DPP4i is necessary for all patients with BP. This retrospective case-control study included 83 patients. The participants were divided into three groups according to their diabetic status and the status of discontinuance or continuance of DPP4i. The 12-month follow-up of the monthly dosage of systemic steroids per body weight (kg) and the percentage of systemic steroid off-therapy in these participants were recorded since the diagnosis of BP. Compared to patients with BP without DM, the 1st, 3rd, and 12th systemic prednisolone doses were significantly lower in the DPP4i group (p = 0.01684, 0.02559, and 0.009336, respectively). The 12th systemic prednisolone dose was significantly lower in patients who discontinued DPP4i (p = 0.0338). Nevertheless, several spontaneous remissions with systemic steroid off-therapy were also noted in the DPP4i-continuance group within 12 months of follow-up. This article supports the favorable impact of DPP4i withdrawal in patients with BP and shows that DPP4i may incite or aggravate BP, resulting in a milder disease course.

Autoimmune bullous disorder flares following severe acute respiratory syndrome coronavirus 2 vaccination: a case series

BACKGROUND

Autoimmune bullous disorders develop due to autoantibodies targeting intercellular adhesion proteins of hemidesmosomes and desmosomes and may be triggered by viral infections and vaccines. Recent reports suggest that the coronavirus disease 2019 vaccination may trigger flares or exacerbations of preexisting autoimmune diseases, including new onset autoimmune bullous disorders. There are less data on whether vaccination against severe acute respiratory syndrome coronavirus 2 may also exacerbate preexisting autoimmune bullous disorders.

CASE PRESENTATION

Here we present three cases, two white males (ages 69 years and 88 years) with bullous pemphigoid and one white 50-year-old female with pemphigus foliaceus, wherein all individuals developed minor, tractable flares of their preexisting autoimmune bullous disorders after receiving the coronavirus disease 2019 vaccination, which were readily treatable with topical or low-dose systemic corticosteroids.

CONCLUSIONS

Dermatologists managing patients with autoimmune bullous disorders should be cognizant of the uncommon potential for flares of the disorder following vaccination for severe acute respiratory syndrome coronavirus 2. Flares of bullous pemphigoid and pemphigus foliaceus following vaccination for severe acute respiratory syndrome coronavirus 2 in these cases were mild and tractable.

Delayed Onset of Bullous Pemphigoid Secondary to Nivolumab

The increasing use of immune checkpoint inhibitors, such as nivolumab, a programmed cell death protein 1 (PD-1) inhibitor, for advanced neoplastic disease has revealed significant cutaneous immune-related adverse effects. Herein, we report a case of bullous pemphigoid (BP) secondary to nivolumab therapy for recurrent metastatic oropharyngeal squamous cell carcinoma. In this patient, the time to development of BP was three years, which represents the most delayed onset of BP secondary to a PD-1 inhibitor that has been reported in the literature. Symptoms were initially controlled on low-dose oral prednisone but recurred after two years. The patient was subsequently treated with a several-month taper of high-dose oral prednisone, during which he was able to resume nivolumab without recurrence of skin lesions. Although immune checkpoint inhibitor-induced BP remains rare, physicians should be aware of this serious cutaneous immune-related adverse event as the use of this drug class continues to expand.

Vesiculobullous Lesions of the Oral Cavity

Several dermatological conditions may manifest in the oral cavity, particularly those that are immune-mediated, and they must be distinguished from the various other types of oral ulcerations. This chapter discusses the clinical features, pathogenesis, differential diagnosis, and diagnostic features, including histology and immunofluorescence findings, as well as management of vesiculobullous diseases. These diseases include pemphigus Vulgaris, benign mucous membrane pemphigoid, bullous pemphigoid, and epidermolysis bullosa acquisita. These diseases have a significant impact on the quality of life, as they can lead to serious complications, depending on the extent of the disease. Therefore, early recognition is crucial, helping to reduce disease-related morbidity, mortality and prevent life-threatening complications.

Chronic pruritus: from pathophysiology to drug design

Pruritus, the most common symptom in dermatology, is an innate response capable of protecting skin against irritants. Nonetheless, when it lasts more than six weeks it is assumed to be a chronic pathology having a negative impact on people's lives. Chronic pruritus (CP) can occur in common and rare skin diseases, having a high prevalence in global population. The existing therapies are unable to counteract CP or are associated with adverse effects, so the development of effective treatments is a pressing issue. The pathophysiological mechanisms underlying CP are not yet completely dissected but, based on current knowledge, involve a wide range of receptors, namely neurokinin 1 receptor (NK1R), Janus kinase (JAK), and transient receptor potential (TRP) ion channels, especially transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1). This review will address the relevance of these molecular targets for the treatment of CP and molecules capable of modulating these receptors that have already been studied clinically or have the potential to possibly alleviate this pathology. According to scientific and clinical literature, there is an increase in the expression of these molecular targets in the lesioned skin of patients experiencing CP when compared with non-lesioned skin, highlighting their importance for the development of potential efficacious drugs through the design of antagonists/inhibitors.

Necrotizing Fasciitis-Severe Complication of Bullous Pemphigoid: A Systematic Review, Risk Factors, and Treatment Challenges

Background and objectives: Bullous pemphigoid (BP), the most common subepidermal autoimmune skin blistering disease (AIBD) has an estimated annual incidence of 2.4 to 42.8 new cases per million in different populations, designating it an orphan disease. Characterized by disruption of the skin barrier combined with therapy-induced immunosuppression, BP could pose a risk for skin and soft tissue infections (SSTI). Necrotizing fasciitis (NF) is a rare necrotizing skin and soft tissue infection, with a prevalence of 0.40 cases per 100,000 to 15.5 cases per 100,000 population, often associated with immunosuppression. Low incidences of NF and BP classify them both as rare diseases, possibly contributing to the false inability of making a significant correlation between the two. Here, we present a systematic review of the existing literature related to the ways these two diseases correlate. Materials and methods: This systematic review was conducted according to the PRISMA guidelines. The literature review was conducted using PubMed (MEDLINE), Google Scholar, and SCOPUS databases. The primary outcome was prevalence of NF in BP patients, while the secondary outcome was prevalence and mortality of SSTI in BP patients. Due to the scarcity of data, case reports were also included. Results: A total of 13 studies were included, six case reports of BP complicated by NF with six retrospective studies and one randomized multicenter trial of SSTIs in BP patients. Conclusions: Loss of skin integrity, immunosuppressive therapy, and comorbidities commonly related to BP patients are risk factors for necrotizing fasciitis. Evidence of their significant correlation is emerging, and further studies are deemed necessary for the development of BP-specific diagnostic and treatment protocols.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Paradoxical phenomena of bullous pemphigoid induced and treated by identical biologics

Objective

This study aimed to investigate the clinical features of biologics-induced bullous pemphigoid (BP) and the therapeutic effects of those agents for BP, exploring the underlying pathophysiological mechanisms.

Methods

We searched PubMed, Web of Science, and Elsevier for studies involving pemphigoid patients treated with or induced by identical biologics published in English from January 2009 to April 2022.

Results

Seventeen cases of drug-induced BP associated with anti-tumor necrosis factor (aTNF)-α therapies, one with interleukin (IL)-17 inhibitors, and seven with IL-12/IL-23 or IL-23 inhibitors were enrolled. Time to cutaneous toxicity varied among different types of agents, and the characteristics of clinical examinations were similar to idiopathic BP. Discontinuation of the culprit drugs and initiation of topical or systemic corticosteroids were adequate in most cases. Several monoclonal antibodies above have also been reported for the treatment of refractory or recurrent BP, especially concurrent with psoriasis.

Conclusion

Biologics for immune-related diseases, including TNF-α, IL-17, and IL-12/IL-23 or IL-23 inhibitors, can both induce and treat BP, which might be associated with a helper T cells Th1/Th2 imbalance, complicated inflammatory networks, and a specific individual microenvironment, suggestive of a new perspective on the therapeutic algorithms of BP. There have been numerous reports about biologics inducing or treating BP. We have taken note of this phenomenon and focused on biologics with both pathogenetic and therapeutic effects on BP. Our review summarized the clinical characteristics of associated cases, trying to figure out the underlying mechanisms of this paradoxical phenomenon and to provide an integrated perspective and new therapeutic alternatives for BP.

Lisinopril prevents bullous pemphigoid induced by dipeptidyl peptidase 4 inhibitors via the Mas receptor pathway

Recent studies have suggested that dipeptidyl peptidase 4 (DPP4) inhibitors increase the risk of development of bullous pemphigoid (BP), which is the most common autoimmune blistering skin disease; however, the associated mechanisms remain unclear, and thus far, no therapeutic targets responsible for drug-induced BP have been identified. Therefore, we used clinical data mining to identify candidate drugs that can suppress DPP4 inhibitor-associated BP, and we experimentally examined the underlying molecular mechanisms using human peripheral blood mononuclear cells (hPBMCs). A search of the US Food and Drug Administration Adverse Event Reporting System and the IBM^® MarketScan^® Research databases indicated that DPP4 inhibitors increased the risk of BP, and that the concomitant use of lisinopril, an angiotensin-converting enzyme inhibitor, significantly decreased the incidence of BP in patients receiving DPP4 inhibitors. Additionally, in vitro experiments with hPBMCs showed that DPP4 inhibitors upregulated mRNA expression of MMP9 and ACE2, which are responsible for the pathophysiology of BP in monocytes/macrophages. Furthermore, lisinopril and Mas receptor (MasR) inhibitors suppressed DPP4 inhibitor-induced upregulation of MMP9. These findings suggest that the modulation of the renin-angiotensin system, especially the angiotensin1-7/MasR axis, is a therapeutic target in DPP4 inhibitor-associated BP.

The Intriguing Links between Psoriasis and Bullous Pemphigoid

The coexistence of psoriasis with autoimmune bullous diseases (AIBDs), particularly bullous pemphigoid (BP), has been documented in case reports and series, as well as in epidemiological studies. The onset of psoriasis precedes that of BP in the majority of cases. Patients with concomitant BP and psoriasis are generally younger at the onset of BP and present with fewer erosions and blisters as compared with patients suffering from isolated BP. Intriguingly, it has been speculated that some BP cases with comorbid psoriasis can actually correspond to anti-laminin gamma-1 pemphigoid, a rare form that was recently recognized as a distinct entity and which can mimic BP and/or other subepidermal AIBDs. The pathomechanisms underlying the BP-psoriasis association have not yet been identified, although several hypotheses have been proposed. The most credited among such hypotheses involves the so-called "epitope spreading" phenomenon, with tissue injury secondary to a primary inflammatory process (i.e., psoriasis) leading to the exposure of sequestered antigens evoking a secondary autoimmune disease (i.e., bullous pemphigoid). This narrative review aims to give a brief overview of the association between psoriasis and BP, examining epidemiological, clinical, and immunopathological features, the pathomechanisms underlying this association, the treatments for psoriasis incriminated as potential triggers of BP, and the therapeutic management of patients with psoriasis and BP.

[Trigger factors associated with bullous autoimmune dermatoses]

BACKGROUND

Blistering autoimmune dermatoses are a heterogeneous group of rare diseases. Pemphigus diseases are distinguished from pemphigoid diseases as well as dermatitis herpetiformis. In pemphigus diseases, cutaneous blistering is caused by an intraepidermal loss of adhesion between keratinocytes. In pemphigoid diseases, blister formation is due to a subepidermal loss of adhesion of keratinocytes from the basement membrane.

OBJECTIVES

This article reviews the most important trigger factors associated with bullous autoimmune dermatoses and discusses their role in their initial manifestation as well as exacerbation.

MATERIALS AND METHODS

A focused review of the literature including original articles, guidelines, reference works and previously published review articles was performed.

RESULTS

Vaccinations, viral infections, ultraviolet light (UV) exposure and radiation therapies are possible triggers of pemphigus vulgaris in predisposed patients. For the much rarer pemphigus foliaceus, UV exposure is of particular importance. Thiols and phenols are drugs that can induce pemphigus usually resembling pemphigus foliaceus clinically. Age is the most important risk factor of bullous pemphigoid. In addition, in bullous pemphigoid associations with dipeptidyl peptidase 4 inhibitors, programmed cell death protein‑1 or programmed death-ligand‑1 inhibitors as well as neurological diseases are particularly relevant. Severe mucosal damage, certain drugs and in particular cases neoplasms might play a role in mucous membrane pemphigoid.

CONCLUSION

Knowing possible trigger factors facilitates a timely diagnosis upon initial manifestation and supports the prevention of relapse of bullous autoimmune dermatoses.

Dipeptidyl Peptidase-4 Inhibitor-Related Bullous Pemphigoid: Clinical, Laboratory, and Histological Features, and Possible Pathogenesis

Dipeptidyl peptidase-4 inhibitor (DPP4i) is a widely used antidiabetic agent. Emerging cases of DPP4i-associated bullous pemphigoid (DBP), whose pathogenesis remains unclear, have been reported. Thus, a retrospective study was conducted from January 2016 to June 2021 to determine the clinical, laboratory, and histopathological features of DBP and idiopathic bullous pemphigoid (IBP). We set up in vitro experiments using vildagliptin-treated HaCaT keratinocytes to validate what we found by analyzing published RNA sequencing data about the genes related to the dermal-epidermal junction. We also observed IL-6 expression by HaCaT cells treated with vildagliptin. We enrolled 20 patients with DBP and 40 patients with IBP. The total Bullous Pemphigoid Disease Area Index (BPDAI) score was similar in both groups. However, the BPDAI score of erosions and blisters in DBP was significantly higher than that in IBP (24.6 vs. 16.68, p = 0.0189), and the score for urticaria and erythema was lower in DBP (12 vs. 19.05, p = 0.0183). The pathological features showed that the mean infiltrating eosinophil number per high-power field was significantly lower in DBP than in IBP (16.7 vs. 27.08, p = 0.023). The expression of LAMA3, LAMB3, LAMC2, DST, and COL17A1 decreased significantly in vildagliptin-treated human keratinocytes. On the other hand, IL-6, the hallmark cytokine of bullous pemphigoid (BP) severity, was found to be upregulated in HaCaT cells by vildagliptin. These experimental findings imply less of a requirement for eosinophil infiltration to drive the inflammatory cascades in DBP blistering. Both immunologic and non-immunologic pathways could be employed for the development of DBP. Our findings may help explain the higher incidence of non-inflammatory BP that was observed in DBP.

A case of acquired hemophilia A and bullous pemphigoid following SARS-CoV-2 mRNA vaccination

Acquired hemophilia is a rare disease resulting from autoantibodies against endogenous factor VIII (FVIII), which associates with bleeding and a high mortality rate. The pathophysiology is still unclear. Recent studies suggest genetic and environmental factors trigger the breakdown of immune tolerance. We report a 77-year-old Taiwanese man presented with multiple ecchymoses and some hemorrhagic blisters three weeks after SARS-CoV-2 mRNA (Moderna) vaccination. Isolated activated partial thromboplastin time (aPTT) prolongation was found. Acquired hemophilia A (AHA) was confirmed by low factor VIII (FVIII) activity and high titer of FVIII inhibitor. The pathohistology of skin biopsy further supported the concomitant diagnosis of bullous pemphigoid. To date, 6 cases of acquired hemophilia A following SARS-CoV-2 mRNA vaccination were reported worldwide. We reviewed and summarized the characteristics of these cases. We also discussed the rare finding of concomitant acquired hemophilia A and bullous pemphigoid. Bullous pemphigoid results from autoantibody against epithelial basement membrane zone of skin. In this article, we proposed possibility of SARS-CoV-2 mRNA vaccine associated autoimmunity against FVIII and epithelial basement membrane zone.

Athena Speciality Certificate Examination case for formulation and systemic therapy

This Athena case describes possible differential diagnoses in a patient with multiple blisters. Histopathology showed subepidermal clefting and superficial dermal inflammation, while immunohistochemistry showed linear deposition of IgG and C3 along the basement membrane zone.

Bullous pemphigoid induced by biologic drugs in psoriasis: a systematic review

INTRODUCTION

Several therapies for psoriasis have been described as triggers of biologic-induced bullous pemphigoid (BIBP). The real incidence of BIBP in psoriatic patients is still unknown. Hence, we compilated and analyzed current literature to identify the frequency and burden of this adverse event for psoriasis patients treated with biologics.

MATERIAL AND METHOD

We systematically searched literature records involving psoriatic patients developing BIBP. Electronic searches were conducted in Pubmed, EMBASE and Scopus in April 2021. To assess the causal relationship between BP and the biologic drug, we applied the Naranjo adverse reaction probability scale and the Karch-Lasagna algorithm.

RESULTS

Our systematic review identified 586 records through the three electronic databases. We identified 15 case reports of BIBP. These cases implicated two cases induced by adalimumab, three by efalizumab, three by etanercept, six by ustekinumab, and one case by secukinumab. Mean period of latency until the BIBP developed was time 5.12 ± 3.44 weeks for TNF-α blockers, and 28.66 ± 26.27 weeks for ustekinumab (p = .09). Most of the cases were assessed as "probable" consistently in both the Naranjo scale and the Karch-Lasagna algorithm.

CONCLUSION

This work presents an accurate estimation on the frequency and burden of BIBP. Ustekinumab presents with the largest evidence of BIBP, especially in patients with previous failure to TNF-α agents. Distinct patterns in the cytokinic pathways and clinical course exist between the BP induced by TNF-α blockers and ustekinumab. A close monitoring of skin condition is highly advisable in patients receiving biologic therapies for psoriasis. Knowledge of BIBP is of great importance to determine the preventive measures and select optimal treatment options.What's already known about this topic?The widespread use of biologic drugs has led dermatologists to encounter increasing situations of biologic-induced BP (BIBP).A lack of data exists on the real incidence of BIBP in psoriatic patients.BIBP is an important adverse event to know when managing patients with psoriasis using biologics.What does this study add?This work presents an accurate estimation on the raised burden of BIBP.Ustekinumab presents with the largest evidence of BIBP, especially in patients with previous failure to TNF-α agents.Mean period of latency until the BIBP developed was time 5.12 ± 3.44 weeks for TNF-α blockers, and 28.66 ± 26.27 weeks for ustekinumab.Distinct patterns in the cytokine pathways and clinical course exist between the BP induced by TNF-α blockers and ustekinumab.A careful screening of previous history of bullous diseases and a baseline immunologic study in psoriatic patients should be advisable prior to commencing any biologic therapy.A close monitoring of skin condition is highly advisable in patients receiving biologic therapies for psoriasis.

Lichen Planus Pemphigoides Associated With PD-1 and PD-L1 Inhibitors: A Case Series and Review of the Literature

ABSTRACT

Immune checkpoint inhibitors are increasingly being used in the treatment of various solid organ and hematologic malignancies. Dermatologic toxicities associated with programmed cell death protein-1 (PD-1) and programmed death ligand-1 (PD-L1) therapy have been widely reported in the literature. It is important for clinicians to be aware of these toxicities to ensure prompt recognition and treatment. Herein, we present the clinical, histopathologic, and immunofluorescence findings of 3 patients diagnosed with lichen planus pemphigoides (LPP) after treatment with anti-PD-1 inhibitors. We also reviewed the literature and summarize 7 previously reported cases of LPP associated with anti-PD-1 and anti-PD-L1 inhibitors. LPP was diagnosed at a median time of 24.4 weeks (range: 4-78 weeks) after initiation of immunotherapy. Clinical findings included papules, plaques, erosions, vesicles, and bullae on the trunk and extremities. Oral involvement was present in half the cases. Histopathologic features of immunotherapy-induced LPP included lichenoid or vacuolar interface dermatitis, the presence of eosinophils, and subepidermal bullae. Direct immunofluorescence demonstrated linear deposition of immunoglobulin G (IgG) or C3. Indirect immunofluorescence demonstrated linear IgG along basement membrane zone on monkey esophagus in 2 cases and linear IgG on the epidermal side of salt split skin in 3 cases. Serum anti-BP180 was elevated in all cases in which enzyme-linked immunosorbent assay was performed.

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

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

Autoimmune Bullous Dermatosis Following COVID-19 Vaccination: A Series of Five Cases

Autoimmune bullous diseases (AIBDs) are a heterogeneous group of diseases characterized by cutaneous and mucosal vesicles, blisters, and erosions. Several factors can trigger this disease, including vaccines; but this entity remains very rare. We hypothesized that vaccination against coronavirus disease 2019 (COVID-19) could trigger an immunological response in genetically predisposed individuals. We report five cases of new-onset autoimmune bullous diseases triggered by the COVID-19 vaccine. Clinical and histopathological examinations confirmed the diagnosis of bullous pemphigoid (BP) in three patients and pemphigus in the other two. According to the French method of imputability, the pharmacovigilance investigation showed an I5B4 causality assessment score for the vaccines, interpreted as highly probable, for all the patients. The diagnosis of vaccine-induced autoimmune bullous dermatosis was highly suspected. One patient's condition improved by dermocorticoids alone, while the other four required oral corticosteroid therapy at 0.5 mg/kg/day, which led to a favorable outcome.

Bullous Pemphigoid Associated With COVID-19 Vaccines: An Italian Multicentre Study

Bullous pemphigoid (BP) is an autoimmune bullous disease caused by circulating autoantibodies toward the hemidesmosomal antigens BP180 and BP230. Cases of BP have been described following vaccinations against tetanus, poliomyelitis, diphtheria, influenza, pneumococcus, meningococcus, hepatitis B and rabies. The putative mechanism by which COVID-19-vaccines may induce BP has not been clarified. An Italian multicentre study was conducted to collect clinical, histopathological and immunopathological data of patients with BP associated with COVID-19-vaccines. Twenty-one cases were collected, including 9 females and 12 males (M/F = 1.3) with a median age at diagnosis of 82 years. Seventeen patients received the COMIRNATY Pfizer-BioNTech vaccine, two the Moderna mRNA-1273 vaccine, one the ChAdOx1/nCoV-19-AstraZeneca/ Vaxzevria vaccine and one received the first dose with the ChAdOx1/nCoV-19-AstraZeneca/Vaxzevria vaccine and the second dose with the COMIRNATY Pfizer-BioNTech vaccine. Median latency time between the first dose of anti-SARS-CoV-2 vaccine and the onset of cutaneous manifestations was 27 days. Median BPDAI at onset was 42. Eleven out of seventeen patients (65%) had positive titres for anti-BP180 antibodies with a median value of 106.3 U/mL on ELISA; in contrast, only five out of seventeen (29%) were positive for anti-BP230 antibodies, with a median of 35.3 U/mL. In conclusion, in terms of mean age, disease severity at diagnosis and clinical phenotype vaccine-associated BP patients seem to be similar to idiopathic BP with an overall benign course with appropriate treatment. On the other hand, the slight male predominance and the reduced humoral response to BP230 represent peculiar features of this subset of patients.

Bullous Pemphigoid Associated With Pembrolizumab Therapy for Non-Small-Cell Lung Cancer: A Case Report

Pembrolizumab is an immune checkpoint inhibitor being increasingly used as immunotherapy for a multitude of cancers. With the increasing use of these agents, various immune-related adverse events are being recognized. Lichenoid reaction, pruritus, and eczema are well-established cutaneous side effects of pembrolizumab, but bullous pemphigoid (BP) is a rare side effect of the drug. It is difficult to establish this diagnosis because it needs a detailed history of the timeline of the evolution of symptoms and careful ruling out of other etiologies, especially other drugs. Here, we present the case of a 66-year-old male who developed BP after receiving pembrolizumab therapy for non-small-cell lung cancer. Discontinuation of pembrolizumab and the use of topical and systemic steroids led to the complete resolution of symptoms. Physicians should be aware of this potential complication and keep it on their differential diagnosis when treating patients on immune checkpoint inhibitors.

Patient Quality of Life Improvement in Bullous Disease: A Review of Primary Literature and Considerations for the Clinician

Autoimmune and inherited bullous disorders are rare skin diseases that may have a profound negative impact on quality of life (QOL). Common symptoms include pain, pruritus, and scarring, and complications may result in the loss of the ability to perform daily tasks. Diagnosis may have a negative psychological impact, and ongoing management may require a significant allocation of time and resources by both patients and providers. To provide patient-centered care, consideration of these factors is of utmost importance for the dermatologist treating patients with bullous disorders. Herein, we present a review of the primary literature evaluating QOL in autoimmune and inherited bullous disorders, including pemphigus, pemphigoid, epidermolysis bullosa, and Hailey-Hailey disease.

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.

Bullous pemphigoid: An immune disorder related to aging (Review)

Bullous pemphigoid (BP) is the most frequent subepidermal autoimmune blistering disease and is caused by autoantibodies directed against two principal antigens of the hemidesmosome, BP antigen 180 and BP antigen 230. The pathogenesis of BP is dependent upon the interaction between genetic predisposition, physiological skin alterations due to aging and specific triggers. Several triggers have already been reported to induce this disease and include drugs, thermal or electrical burns, surgical procedures, trauma, UV radiation, radiotherapy, chemicals and infections. Data from the current literature support the hypothesis that alterations of the skin barrier associated with aging increase individual susceptibility to these aforementioned triggers. Consequently, this has been reported to lead to the attack of autoantibodies, demonstrating the predilection of BP for the elderly population. The identification of triggering factors and comorbidities may aid in understanding the pathogenesis of BP and improve clinical management by encouraging their prompt recognition and removal. Moreover, the present review has indicated that current management of BP should be aimed at counteracting the detrimental effects of aging on the skin by restoring skin barrier integrity and maintaining cutaneous homeostasis, for example with systematic applications of topical emollients and photoprotection. This strategy could prove even more beneficial in the elderly, in which frequent comorbidities associated with age often narrow available immunosuppressive treatment options. Furthermore, the safety of treatment regimens may significantly affect outcome and prognosis.

Bullous pemphigoid in diabetic patients treated by gliptins: the other side of the coin

Bullous pemphigoid (BP) is the most common autoimmune bullous skin disease that affects primarily patients older than 60 years. The majority of BP cases are spontaneous, but BP can also be triggered by certain drugs’ exposures. Since 2011, a growing number of observations has been reporting cases of BP in Type 2 diabetic patients. These forms have been linked to the use of a new category of anti-diabetic drugs called dipeptidyl peptidase inhibitors (DPP-4i) or gliptins, but to date, the exact pathophysiological mechanisms underlying this association are not completely elucidated. Although conventional and gliptin-associated BP are thought to share similar clinical and histopathological features, our thorough review of the most recent literature, shows that these 2 forms are quite distinct: DPP-4-i-associated BP seems to appear at an earlier age than spontaneous BP, it may manifest either as a noninflammatory or inflammatory phenotype, while the conventional form presents with a typical inflammatory phenotype. Additionally, an important distinctive histological feature was recently shown in Gliptin-associated BP: these forms may present a less significant eosinophils infiltrate in the upper dermis of peri-blister lesions compared to the skin of patients with spontaneous BP, and this seems a specific feature of the clinically non-inflammatory forms. In accordance with previous literature, we found that the direct immunofluorescence (DIF) gives identical findings in both DPP-4i-associated and conventional forms of BP which is an IgG and complement C3 deposition as a linear band at the dermal–epidermal junction in perilesional skin. Indirect immunofluorescence shows the presence of IgG circulating autoantibodies in the patient's serum which titer does not differ between spontaneous and DPP-4i-associated BP, while the specificity of these autoantibodies, may be different in spontaneous, induced non-inflammatory and induced inflammatory forms, epitope spreading phenomenon seems to play a role in determining these specificities. Further research, based on integrated epidemiological, clinical, histo-immunological and pharmacogenomic approaches, may give more insight into these forms of BP. This combined approach will allow to better define BP endotypes and to unveil the mechanism of spontaneous or drug-induced breakage of the immunotolerance to skin self-antigens.

The pathogeneses of pemphigus and pemphigoid diseases

Autoimmune bullous diseases (AIBDs) are skin disorders which are mainly induced by autoantibodies against desmosomal or hemidesmosomal structural proteins. Previous studies using patients' samples and animal disease models identified target antigens and elucidated the mechanisms of blister formation. Pemphigus has been the subject of more active clinical and basic research than any other AIBD. These efforts have revealed the pathogenesis of pemphigus, which in turn has led to optimal diagnostic methods and novel therapies, such as rituximab. In bullous pemphigoid (BP), studies with passive-transfer mouse models using rabbit anti-mouse BP180 antibodies and studies with passive-transfer or active mouse models using autoantigen-humanized mice elucidated the immune reactions to BP180 in vivo. Recently, dipeptidyl peptidase-4 inhibitors have attracted attention as a trigger for BP. For epidermolysis bullosa acquisita (EBA), investigations using mouse models are actively under way and several molecules have been identified as targets for novel therapies. In this review, we give an overview and discussion of the recent progress in our understanding of the pathogenesis of pemphigus, BP, and EBA. Further studies on the breakdown of self-tolerance and on the identification of key molecules that are relevant to blister formation may expand our understanding of the etiology of AIBDs and lead to the development of novel therapeutic strategies.

Rivaroxaban-Associated Bullous Pemphigoid in a Patient With Atrial Fibrillation

Rivaroxaban is commonly used for prevention of thromboembolic diseases in patients with atrial fibrillation. We report a case of an 86-year-old man with hypertension, chronic kidney disease, type 2 diabetes mellitus, dyslipidemia, and atrial fibrillation who developed bullous eruptions 1 week after a rivaroxaban dose increase. He was subsequently hospitalized, and direct immunofluorescence confirmed bullous pemphigoid (BP). After switching to apixaban, the patient's skin eruptions stabilized and improved. This is the first reported case of immunofluorescence-confirmed BP associated with rivaroxaban use. Prompt discontinuation of rivaroxaban and a switch to other anticoagulants is important for patients with suspected drug-associated BP.