Unique clinical and serological features of bullous pemphigoid associated with dipeptidyl peptidase-4 inhibitors

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.

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.

Analysis of IL-10 and IL-35 in dipeptidyl peptidase-4 inhibitor-related bullous pemphigoid

The association between immunoregulatory cytokines, such as interleukin (IL)-10 or IL-35, and dipeptidyl peptidase-4 inhibitor (DPP4i)-related bullous pemphigoid (BP) has not been evaluated. Serum IL-10 and IL-35 levels were measured in 39 patients with BP (24 males and 15 females; 6 DPP4i-related and 33 DPP4i-unrelated BP patients) and 10 healthy controls. The number of CD26+ cells in the dermis around bulla on sections was counted immunohistochemically for 12 patients (six patients with DPP4i-related BP and six randomly sampled patients with DPP4i-unrelated BP). Patients with DPP4i-related BP had lower levels of serum eosinophils (DPP4i-related vs. DPP4i-unrelated BP: 476.1 ± 234.0 vs. 911.3 ± 948.8/μL; p = 0.537) and a higher rate of infiltrating CD26+ cells (32.9 ± 7.1% vs. 15.7 ± 4.4%; p = 0.01). There were no significant differences in serum IL-10 (6.77 ± 0.24 vs. 6.84 ± 0.20 pg/mL), serum IL-35 (2.63 ± 0.17 vs. 2.63 ± 0.21 pg/mL), serum anti-BP180NC16a antibodies (67.31 ± 37.4 vs. 76.18 ± 54.59 U/mL) and Bullous Pemphigoid Disease Area Index before treatment in this study. Serum IL-10 and IL-35 levels do not increase in patients with BP and may not be a candidate for a therapeutic target for BP. An increase in CD26+ cells might be associated with DPP4i-related BP.

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.

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.

Clinical Phenotypes and the Clinical Course of Bullous Pemphigoid Receiving Dipeptidyl Pepitidase-4 Inhibitor Treatment: An Analysis of Cases in a Single Japanese Center

Objective Several studies have shown an increased risk of bullous pemphigoid (BP) when receiving dipeptidyl pepitidase-4 inhibitor (DPP-4i) treatment. The present study explored the associations of DPP-4i treatment with the clinical phenotypes and clinical course of BP. Methods We analyzed data of 146 patients with BP at Tokai University School of Medicine from December 1, 2009, to December 31, 2021. We obtained data by a retrospective medical record review and compared the bullous pemphigoid disease area index (BPDAI) between diabetes patients receiving DPP-4i treatment and those not receiving DPP-4i treatment. We employed multivariable linear regression models to explore the association between the DPP-4i treatment and the BPDAI scores. Results Among 53 BP patients with diabetes, 33 had developed BP during treatment with DPP-4i agents, among which vildagliptin was the most frequently used. The urticaria/erythema scores of the BPDAI were significantly lower in patients who developed BP while receiving DPP-4i treatment than among others. Of note, 69.2% of the patients who stopped DPP-4i treatment experienced complete remission, and the clinical course was more favorable in patients with lower scores for urticaria/erythema than among others. Conclusion These findings suggest that, in patients who developed BP while receiving DPP-4i treatment, a noninflammatory phenotype may indicate a high likelihood that DPP-4i treatment contributes to the development of BP. The discontinuation of DPP-4i should be carefully considered in close consultation with dermatologists.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Clinical features of dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid in Japan: A nationwide retrospective observational study

Many cases of bullous pemphigoid (BP) have been reported in patients taking dipeptidyl peptidase-4 inhibitors (DPP-4i), which are the most widely used antidiabetic drug for type 2 diabetes mellitus. However, no large-scale survey has been conducted in Japan. This retrospective study investigated the incidence, clinical presentation, and clinical course of DPP-4i-associated BP (DPP-4i-BP) using epidemiological data from a nationwide registry for BP. In 2016, 713 new BP patients at 94 dermatological institutes were registered, 243 (34.1%) with DPP-4i-BP and 461 (64.7%) with non-DPP-4i-BP. The male-to-female ratio was 1.9 and 0.84, respectively. Patients with DPP-4i-BP were predominantly male. Non-inflammatory BP was more common in DPP-4i-BP (33.3%) than in non-DPP-4i-BP (14.6%), while inflammatory BP was common in both. No specific subtype or difference in disease severity was evident in DPP-4i-BP. The most common gliptins administered to DPP-4i-BP patients were vildagliptin (37.2%) and linagliptin (23.8%). DPP-4i intake was discontinued in 79.9% of cases after diagnosis. Some DPP-4i-BP patients (17.6%) achieved spontaneous remission after discontinuing DPP-4i without requiring the use of systemic corticosteroids and/or adjuvant therapy. Mean duration to achieve disease control was 2.87 months. The odds ratio for non-inflammatory BP requiring systemic corticosteroids and/or adjuvant therapy was low (0.52), suggesting that remission was achieved easily with supportive care in that phenotype. Non-inflammatory and mild cases of DPP-4i-BP may resolve spontaneously with supportive care, including the discontinuation of DPP-4i and no oral corticosteroid therapy.

Bullous Pemphigoid in Patients Receiving Immune-Checkpoint Inhibitors and Psoriatic Patients—Focus on Clinical and Histopathological Variation

Background: The most common autoimmune blistering disease, bullous pemphigoid (BP), shows an increased prevalence in psoriatic patients and oncologic patients undergoing immune-checkpoint blockade (ICB). Even though the same autoantigens (BP180/BP230) are detectable, it remains obscure whether clinical or histopathological differences exist between these different groups of BP patients. In this study, we strived to analyze this matter based on own data and previously published reports. Methods: We performed an institutional chart review from 2010–2020 to identify BP patients with psoriasis (n = 6) or underlying ICB (n = 4) and matched them with idiopathic cases of BP (n = 33). We compared clinical characteristics, subtypes, and dermatopathological determinants (e.g., tissue eosinophilia/neutrophilia, papillary edema, lymphocytic infiltration) among the groups. Results: ICB-associated BP affects men more often and might show mucosal involvement more frequently. We found no statistically significant dermatopathological differences among the groups. Conclusions: Clinicians should be aware of an increased risk of BP in patients with psoriasis and oncologic patients receiving ICB; atypical pruritic skin lesions should prompt a workup including a skin biopsy for histopathology and direct immunofluorescence in these patients. Larger studies might be necessary to detect slight dermatopathological variation.

Gliptin-associated bullous pemphigoid shows peculiar features of anti-BP180 and -BP230 humoral response: results from a multicenter study

BACKGROUND

Recently, several case-control studies demonstrated an association between gliptins and bullous pemphigoid (BP) occurrence. Data on clinical and immunological features of gliptin-associated bullous pemphigoid (GABP) are controversial.

OBJECTIVE

This study aims to clinically and immunologically characterize a large cohort of GABP patients to get insight into the pathophysiology of this emerging drug-induced variant of BP.

METHODS

Seventy-four GABP patients were prospectively enrolled and characterized from nine different Italian Dermatology Units between 2013 and 2020.

RESULTS

Our findings demonstrate that in GABP patients: i) the non-inflammatory phenotype which is characterized by low amounts of circulating and skin infiltrating eosinophils is frequently found; ii) IgG, IgE and IgA humoral response to BP180 and BP230 antigens is reduced in frequency and titers when compared with idiopathic BP; iii) IgG reactivity targets multiple BP180 epitopes other than NC16A.

LIMITATIONS

A limitation of the study is the control group that did not comprise only type 2 diabetes mellitus BP patients.

CONCLUSIONS

GABP patients show peculiar features of anti-BP180 and -BP230 humoral response laying the foundations for diagnostic improvements and to get novel insights into understanding the mechanism of BP onset.

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.

Dipeptidyl peptidase-4 inhibitor-induced autoimmune diseases: Current evidence

Dipeptidyl peptidase-4 inhibitors (DPP-4i) have an important place in the management of type 2 diabetes. The DPP-4 enzyme is ubiquitously distributed throughout the human body and has multiple substrates through which it regulates several important physiological functions. DPP-4 regulates several immune functions, including T-cell activation, macrophage function, and secretion of cytokines. Studies have reported an increase in autoimmune diseases like bullous pemphigoid, inflammatory bowel disease, and arthritis with DPP-4i use. The relationship of DPP-4i and autoimmune diseases is a complex one and warrants further research into the effect of DPP-4 inhibition on the immune system to understand the pathogenesis more clearly. Whether a particular cluster of autoimmune diseases is associated with DPP-4i use remains an important contentious issue. Nevertheless, a heightened awareness from the clinicians is required to identify and treat any such diseases. Through this review, we explore the clinical and pathophysiological characteristics of this association in light of recent evidence.

Dipeptidyl peptidase 4 inhibitor-associated mucous membrane pemphigoid

Dipeptidyl peptidase 4 inhibitors (DPP-4i) are associated with an increased risk of developing bullous pemphigoid (BP) in patients with diabetes. Autoantibodies targeting epitopes on the processed BP180, 120-kDa (LAD-1), and 97-kDa (LABD97) linear immunoglobulin (Ig)A dermatosis antigens are the major autoantibodies in DPP-4i-associated BP. However, no case of mucous membrane pemphigoid (MMP) developing during treatment with DPP-4i has been reported. We report a case of MMP associated with DPP-4i. A man in his late 70s presented with oral mucous membrane erosion and a few blisters on his upper chest and back. He had used linagliptin for diabetes for over 1 year when he presented. The immunological characteristics were similar to DPP4i-associated BP: higher reactivity to LAD-1 and LABD97 than to the full-length BP180. The aphthae achieved remission after oral linagliptin was replaced with sitagliptin. However, 6 months later, the aphthae relapsed and any DPP-4i was discontinued. The aphthae disappeared, and now he is completely free from lesions associated with MMP. This case suggests that the DPP-4i may have shared roles in the production of IgG antibodies to LAD-1 or to LABD97 in the pathogenesis of DPP-4i-associated BP and MMP. Our case highlights the possibility of overlooking the mild MMP in DPP-4i-treated diabetes patients with mucosal lesions.

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

BACKGROUND AND OBJECTIVES

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The impact of lesional inflammatory cellular infiltrate on the phenotype of bullous pemphigoid

BACKGROUND

The influence of cutaneous cellular infiltration on the phenotype of bullous pemphigoid (BP) remains to be established.

OBJECTIVES

To evaluate the main histopathological characteristics of patients with BP and to assess the association between the composition of lesional inflammatory infiltrate and the various clinical, immunological and immunopathological aspects of the disease.

METHODS

Retrospective study encompassing patients diagnosed with BP throughout the years 2009-2020 in a specialized tertiary referral centre.

RESULTS

The study encompassed 136 patients with BP, of whom 27 (19.9%) demonstrated a cell-poor inflammatory infiltrate in lesional skin specimens. Overall, 78 (57.4%), 71 (52.2%) and 5 (3.7%) specimens were found to include eosinophil-predominant, lymphocyte-predominant and neutrophil-predominant inflammatory infiltrates, respectively. Relative to the remaining patients with BP, those with an eosinophil-predominant inflammatory infiltrate had higher (90.8% vs. 77.2%; P = 0.030) whilst those with a cell-poor inflammatory infiltrate lower (70.3% vs. 88.7%; P = 0.017) seropositivity of anti-BP180 NC16A IgG. The latter subgroup presented with higher prevalence of mucosal involvement (25.9% vs. 8.3%; P = 0.011) and a non-inflammatory clinical phenotype (50.0% vs. 17.1%; P = 0.041). Patients with lymphocyte-predominant inflammatory infiltrate manifested with higher severity BPDAI scores and a lower frequency of the non-inflammatory subtype (11.1% vs. 36.4%; P = 0.035), whilst those with a neutrophilic infiltrate presented with lower mean (SD) levels of anti-BP180 NC16A IgG [269.3 (227.6) vs. 722.7 (1499.6) U/mL; P = 0.003].

CONCLUSIONS

Eosinophil-predominance and high cellularity in the lesional inflammatory infiltrate of BP skin are associated with increased seropositivity of anti-BP180 NC16A IgG. Lymphocyte-predominant infiltrates predict a more severe phenotype, pointing towards a pathogenic role of autoreactive lymphocytes.

Recent developments in the pathogenesis of pruritus in bullous pemphigoid

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

Defining dipeptidyl peptidase-4 inhibitors-related bullous pemphigoid: A single-centre retrospective study

BACKGROUND

Many studies have corroborated the association of dipeptidyl peptidase-4 inhibitors (DPP4i) use with bullous pemphigoid (BP). It has been speculated that this drug-induced variant presents with a different clinical spectrum than conventional BP.

OBJECTIVE

To determine the prevalence of DPP4i-induced cases of BP and to evaluate whether gliptin-related BP has specific clinicopathological and immunological features.

METHODS

We conducted a retrospective, observational study of BP cases attended at our centre between January 2000 and June 2020. Epidemiological, clinical, histopathological and laboratory data were collected.

RESULTS

A total of 257 cases of BP were collected; 51 (24.3%) were on treatment with DPP4i. When analysing DPP4i-induced BP cases, generalized BP was the predominant pattern and scalp/mucosal involvement was found in 13 patients. Gliptin-related BP cases were associated to a decrease in the eosinophilic infiltrate (p = 0.000) and both the detection rate and concentration of anti-BP180 IgG were lower (p = 0.004, p = 0.001, respectively) than non-DPP4i cases.

LIMITATIONS

Retrospective, single-centre study.

CONCLUSION

Our large DPP4i-induced BP case series has highlighted that DPP4i-induced BP is characterized by generalized lesions and scalp involvement. Lower titres of anti-BP180 antibodies and a decrease in eosinophils infiltrating into the skin may be distinct features of DPP4i-related BP.

Clinical, Laboratory and Histological Features of Dipeptidyl Peptidase-4 Inhibitor Related Noninflammatory Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease of elderly patients that has shown increasing incidence in the last decades. Higher prevalence of BP may be due to more frequent use of provoking agents, such as antidiabetic dipeptidyl peptidase-4 inhibitor (DPP4i) drugs. Our aim was to assess DPP4i-induced bullous pemphigoid among our BP patients and characterize the clinical, laboratory and histological features of this drug-induced disease form. In our patient cohort, out of 127 BP patients (79 females (62.2%), 48 males (37.7%)), 14 (9 females and 5 males) were treated with DPP4i at the time of BP diagnosis. The Bullous Pemphigoid Disease Area Index (BPDAI) urticaria/erythema score was significantly lower, and the BPDAI damage score was significantly higher in DPP4i-BP patients compared to the nonDPP4i group. Both the mean absolute eosinophil number and the mean periblister eosinophil number was significantly lower in DPP4i-BP patients than in nonDPP4i cases (317.7 ± 0.204 vs. 894.0 ± 1.171 cells/μL, p < 0.0001; 6.75 ± 1.72 vs. 19.09 ± 3.1, p = 0.0012, respectively). Our results provide further evidence that DPP4i-associated BP differs significantly from classical BP, and presents with less distributed skin symptoms, mild erythema, normal or slightly elevated peripheral eosinophil count, and lower titers of BP180 autoantibodies. To our knowledge, this is the first case series of DPP4i-related BP with a non-inflammatory phenotype in European patients.

Clinical characteristics and outcomes of bullous pemphigoid patients with versus without oral prednisolone treatment

Bullous pemphigoid (BP) varies in severity and stratified treatments are needed. However, there are no definitive standards for choosing appropriate treatments. To elucidate the factors involved in choosing treatments and the clinical outcomes of BP, we retrospectively reviewed the clinical records of 78 BP patients at a single center. Of the 78 patients, 49 (62.8%) were treated with oral prednisolone (PSL) and 29 (37.2%) were treated without PSL. The patients with older age, lower Bullous Pemphigoid Disease Area Index (BPDAI), and/or lower anti-BP180NC16a antibody titer at onset tended to be treated without oral PSL. Notably, only 9.1% patients without PSL experienced relapse, whereas 36.7% patients with oral PSL experienced relapse when the PSL was around 0.1 mg/kg. It suggests that the patients with mild disease severity could be well controlled without oral PSL. Receiver-operator curve analysis demonstrated that the cut-off value for the use of oral PSL was 31 for total BPDAI and was 7 for BPDAI skin urticaria/erythema, with a high (>0.9) area under the curve. Notably, none of the patients who were negative for the anti-BP180NC16a antibody at onset experienced relapse even though they were treated without PSL. In conclusion, in BP patients who were negative for anti-BP180NC16a antibody at onset, with a total BPDAI score of less than 31 or with an urticaria/erythema score of less than 7 can be treated without PSL. When the PSL is tapered to around 0.1 mg/kg, we should carefully monitor the patients to detect relapse.

Milestones in Personalized Medicine in Pemphigus and Pemphigoid

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

More Severe Erosive Phenotype Despite Lower Circulating Autoantibody Levels in Dipeptidyl Peptidase-4 Inhibitor (DPP4i)-Associated Bullous Pemphigoid: A Retrospective Cohort Study

BACKGROUND

The clinical and immunological profile of patients with dipeptidyl peptidase-4 inhibitor (DPP4i)-associated bullous pemphigoid (BP) is inconsistent in the current literature.

OBJECTIVES

The aims were to investigate the clinical and immunological features of patients with DPP4i-associated BP and to examine whether there are intraclass differences between different DPP4i agents.

METHODS

A retrospective cohort study was conducted, including all consecutive patients diagnosed with BP throughout the years 2009-2019 in a tertiary referral center.

RESULTS

The study encompassed 273 patients with BP (mean age at diagnosis 79.1 ± 9.9 years), of whom 24 (8.8%) were associated with DPP4i. Sitagliptin was the prescribed agent for 17 patients (70.8%), and vildagliptin was prescribed in seven patients (29.2%). Relative to other patients with BP, patients with DPP4i-associated BP had more prominent truncal involvement (95.8% vs. 73.9%; P = 0.017), greater erosion/blister Bullous Pemphigoid Disease Area Index (BPDAI) subscore (29.8 ± 17.4 vs. 20.6 ± 14.4; P = 0.018), and lower levels of anti-BP180 NC16A (279.2 ± 346.1 vs. 572.2 ± 1352.0 U/ml; P = 0.009) and anti-BP230 (25.5 ± 47.8 vs. 128.6 ± 302.9 U/ml; P = 0.009) antibodies. Relative to patients with sitagliptin-associated BP, those with vildagliptin-associated BP had a lower seropositivity rate (57.1% vs. 94.1%, P = 0.031) and lower levels (96.7 ± 139.0 vs. 354.5 ± 376.5; P = 0.023) of anti-BP180 NC16A antibodies, and tended to present with higher erosion/blister BPDAI subscore (36.3 ± 9.6 vs. 25.8 ± 19.7; P = 0.095).

CONCLUSIONS

DPP4i-associated BP is characterized by a more severe blistering and erosive presentation despite lower levels of typically pathogenic antibodies.

Gliptin-Induced Bullous Pemphigoid: Canadian Case Series of 10 Patients

BACKGROUND

Bullous pemphigoid (BP) is a chronic immune-mediated vesiculobullous disorder. Recently, several reports have described dipeptidyl peptidase-4 inhibitors, also known as gliptins, as causative agents for drug-induced BP.

OBJECTIVE

To report and describe clinical and histologic characteristics of 10 cases of gliptin-induced BP.

RESULTS

We identified 10 patients with gliptin-induced BP. Nine were secondary to linagliptin, and 1 case was attributed to sitagliptin. All patients showed significant improvement after withdrawal of gliptin medications and proper medical treatment. There has been no evidence of relapse after 4 months of follow-up.

CONCLUSION

This report supports the proposed association between gliptins and BP. Physicians should be aware of this potential adverse effect, as gliptin-induced BP can be reversible once identified and the responsible medication is stopped. Early withdrawal of the offending drug and proper treatment can lead to rapid improvement and reduced morbidity.

Clinical Features and Outcomes of Dipeptidyl Peptidase-4 Inhibitor-Associated Bullous Pemphigoid (DPP4i-Associated BP) in Thai Patients

The use of dipeptidyl peptidase-4 inhibitors (DPP4i) appears to be associated with a small but significantly elevated risk of bullous pemphigoid (BP). Although the pathogenic mechanism of DPP4i-associated BP remains unclear, this adverse event is reported with multiple gliptins, suggesting a class effect. However, previous studies from various countries showed that vildagliptin had been implicated in most cases. The aim of this study was to illustrate a case series of DPP4i-associated BP in Thai patients. We conducted a retrospective study from consecutive cases of BP in people with type 2 diabetes mellitus (T2DM) from January 2008, the year in which the first DPP4i was introduced in Thailand, until December 2019. During the study period, 10 BP patients with T2DM were identified. A total of 5 DPP4i-associated BP (3 on vildagliptin, 1 on linagliptin, and 1 on sitagliptin) were found. All patients were male with a mean age at BP development of 80.4 years (73–86 years). All patients had a long-standing duration of diabetes (median duration 34 years), and mean A1C was 7.5 ± 1.4%. The median time to BP development after the introduction of DPP4i was 64 months (range 20–128 months). The severity of BP was classified as mild in 2 cases. In all cases, the association between the drug intake and BP onset was classified as “possible” according to the Naranjo causality scale. All of the patients continued taking DPP4i after BP diagnosis, and one patient died of lung cancer 18 months after BP diagnosis. Only 2 patients could achieve complete remission at least 2 months after stopping DPP4i. Our case series demonstrated a potential link between DPP4i and the development of BP, which mainly occurred in very elderly male patients. The latency period from an introduction of DPP-4i could be several years, and the clinical course after DPP4i discontinuation varied. Clinicians prescribing DPP4i should be aware of this association and consider stopping this medication before a refractory disease course ensues.

Regulatory T cell subsets in bullous pemphigoid and dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid

BACKGROUND

Regulatory T (Treg) cells play an essential role in peripheral immune tolerance. Bullous pemphigoid (BP) is the most common blistering disease and is caused by autoantibodies to two BP antigens: type XVII collagen and BP230. Recently, we reported that Treg cell dysfunction may cause the production of autoantibodies to BP antigens. Several studies have suggested an association between Treg cells and BP pathogenesis. However, Treg cells are heterogeneous in humans, leading to inconsistent results in previous studies.

OBJECTIVE

To assess functional Treg subsets in BP.

METHODS

We examined three distinct Treg subsets in conventional BP (cBP) patients before versus after systemic corticosteroid treatment, dipeptidyl peptidase-4 inhibitor-associated BP (DPP-4i-BP) patients, younger controls and older controls.

RESULTS

We found that total Treg cells and all Treg cell subsets were increased in cBP patients before treatment and decreased by systemic corticosteroid treatment. In contrast, neither total Treg cells nor all Treg subsets were increased in DPP-4i-BP. Notably, CD45RA- Foxp3hi effector Treg cells positively correlated with disease severity in cBP, whereas CD45RA+Foxp3lo naïve Treg cells positively correlated with the disease severity in DPP-4i-BP.

CONCLUSION

These findings suggest that Treg cells are differently involved in the pathogeneses of cBP and DPP-4i-BP.

Dipeptidyl-peptidase IV inhibitors (DPP4i)-associated bullous pemphigoid: Estimating the clinical profile and exploring intraclass differences

Data regarding the clinical characteristics of patients with dipeptidyl-peptidase IV inhibitors (DPP4i)-associated BP is inconclusive. We aimed to characterize the clinical features of patients with DPP4i-associated BP, and to assess whether there are phenotypic differences associated with different agents belonging to the DPP4i class. A retrospective prevalence study was performed, including all consecutive patients diagnosed with BP throughout the years 2000 to 2019. The study included 397 patients with BP, of whom 58 (14.6%) were DPP4i-associated. Compared to other patients with BP, patients with DPP4i-associated BP had a more prominent male preponderance (60.3% vs 41.0%; P = .006), presented more frequently with extensive disease (60.3% vs 46.3%; P = .049), had greater truncal (96.6% vs 85.5%; P = .019) and cephalic (51.7% vs 33.6%; P = .008) involvement, and had less frequent peripheral eosinophilia (25.9% vs 51.9%; P < .001). Compared to patients with vildagliptin-associated BP, those with linagliptin-associated BP were managed by higher dosage of systemic corticosteroids in order to achieve disease control (prednisone > 1 mg/kg: 68.2% vs 40.0%; P = .046). In conclusion, DPP4i-associated BP seems to have a unique clinical profile characterized by male predominance, extensive disease, truncal and cephalic involvement, and less peripheral eosinophilia. Linagliptin may be associated with a harder course necessitating more aggressive therapy.

Eosinophils in Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disorder with substantial morbidity and mortality. BP is regarded as a disorder driven by IgG due to BP180 and BP230 IgG autoantibodies, yet, new advances highlight the function of eosinophils and IgE autoantibodies in BP. Evidence supports that eosinophils are involved in BP pathogenesis, notably, these include the presence of IL-5, eotaxin, and eosinophil-colony stimulating factor in blister fluid, peripheral blood eosinophilia is present in nearly 50% of affected patients, eosinophils are found against the dermo-epidermal junction (DEJ) when BP serum is present, metalloprotease-9 is secreted by eosinophils at blister sites, blister fluid of BP patients contains eosinophil granule proteins which are located along the lamina lucida of the BMZ in patients with BP and correspond with disease clinically, eosinophil extracellular traps (EET) have been linked to DEJ splitting, IL-5 activated eosinophils cause DEJ separation when BP serum is present, and eosinophils are requisite to drive anti-BP180 IgE mediated blistering of the skin. Yet, the mechanism whereby eosinophils contribute to the pathogenesis of BP remains to be explored. In this review, we examine the role of eosinophils in BP while offering a basis to explain the pathomechanisms of eosinophils in BP.

Increased risk of bullous pemphigoid in dipeptidyl peptidase 4 inhibitors: A nationwide, population-based, cohort study in Taiwan

Recent studies revealed the risk of bullous pemphigoid (BP) in patients with diabetes mellitus (DM) taking dipeptidyl peptidase 4 (DPP-4) inhibitors. To clarify the relationship between taking DPP-4 inhibitors and the risk of BP among patients with DM, we conducted a cohort study by using the National Health Insurance Research Database of Taiwan from 1 January 2009 to 31 December 2015. We identified 6340 patients with DM taking DPP-4 inhibitors and 25 360 DM patients who had not taken DPP-4 inhibitors during the 7-year follow-up period. Compared with the non-DPP-4 inhibitor group, patients taking DDP-4 inhibitors had a higher risk of BP (adjusted hazard ratio [aHR], 2.382; 95% confidence interval (CI), 1.163-4.883; P = 0.017]. Among the DPP-4 inhibitors available in Taiwan, vildagliptin showed the highest risk of BP (aHR, 2.849; 95% CI, 1.893-4.215; P < 0.001), followed by saxagliptin (aHR, 2.657; 95% CI, 1.770-3.934; P < 0.001). Subgroup analysis revealed that the higher risk of BP was observed in patients older than 65 years (aHR, 2.403; 95% CI, 1.590-3.627; P < 0.001). This study revealed that treatment with DPP-4 inhibitors, especially vildagliptin, was significantly associated with an increased risk of BP among DM patients.

Bullous pemphigoid associated with dipeptidyl peptidase-4 inhibitors. A case series and analysis of cases reported in the Spanish pharmacovigilance database

BACKGROUND

Bullous pemphigoid (BP) has been associated with dipeptidyl peptidase-4 inhibitors (DPP4i). Clinical features, outcomes, and risk of BP for new DPP4i (linagliptin, saxagliptin, and alopgliptin) are not well established. Comparison of risk of BP appearance for DPP4i and other oral antidiabetic drugs (OADs) such as sodium glucose cotransporter 2 inhibitors has not been studied to date.

OBJECTIVES

To describe the prevalence, sociodemographic, clinical, and histopathological characteristics, and outcome after drug withdrawal in DPP-4i-associated BP cases from our hospital. To review all Spanish spontaneous notifications of BP where DPP4i or OADs were included as suspected drugs and calculate the reporting odds ratios (RORs).

METHODS

A retrospective observational study was performed examining the association between DDP4i and BP. Clinical features and RORs were analyzed. Data from the Spanish Pharmacovigilance System (SEFV) are included.

RESULTS

In our center, 28 of 89 patients with BP (31.5%) were under DPP4i treatment; 53.6% were male, and mean age was 80.8 years. BP debuted the first year after DPP4i in 57.2%. BP control was achieved within 3.7 months after drug withdrawal. Regarding SEFV, 22 of 972 spontaneous notifications were related to BP and DPP4i. RORs were superior for DPP4i compared to other OADs. Vildagliptin had the highest ROR.

CONCLUSIONS

We present the largest DPP4i-induced BP case series in a single center, with a detailed study of the sociodemographic, clinical, and histopathological characteristics of each patient, and their treatment and outcome. Vildagliptin had the highest risk. DPP4i-associated BP does not seem to have specific clinical characteristics.

Checkpoint Inhibition May Trigger the Rare Variant of Anti-LAD-1 IgG-Positive, Anti-BP180 NC16A IgG-Negative Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering skin disease characterized by an autoimmune response to type XVII collagen (BP180). The generation of anti-BP180-NC16A IgG autoantibodies is considered to be central to the pathogenesis of BP, in part due to the close correlation between serum concentration and disease activity. However, ~60% of BP patients also generate IgG autoantibodies against LAD-1, the soluble 120 kDa ectodomain of BP180. Whilst the pathogenic significance of anti-LAD-1 IgG remains unclear, it may be sufficient to precipitate the development of BP, even in the absence of anti-BP180-NC16A IgG, based on several case reports in Japanese patients. There is increasing recognition that immune-checkpoint inhibitors may trigger and/or exacerbate BP as an immune-related adverse event (irAE). Until now, all of these cases have been associated with the induction of anti-BP180-NC16A IgG. Here, we report the case of a female Caucasian patient who developed BP during treatment with the programmed cell death protein 1 (PD-1) inhibitor nivolumab. Intriguingly, the patient exclusively generated anti-LAD-1 IgG, suggesting that anti-LAD-1 IgG was responsible for the development of her autoimmune blistering dermatosis. This is the first such case documented in a non-Japanese patient, thus, lending further support to the pathogenic relevance of anti-LAD-1 IgG in BP.

[What's new in clinical dermatology?]

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

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.

Preferential Reactivity of Dipeptidyl Peptidase-IV Inhibitor-Associated Bullous Pemphigoid Autoantibodies to the Processed Extracellular Domains of BP180

Bullous pemphigoid (BP) is a common autoimmune blistering disease in which autoantibodies target the hemidesmosomal components BP180 and/or BP230 in basal keratinocytes. In BP, 80 to 90% of autoantibodies target the juxtamembranous extracellular non-collagenous 16th A (NC16A) domain of BP180. Recently, the administration of dipeptidyl peptidase-IV inhibitors (DPP4i), which are widely used as antihyperglycemic drugs, has been recognized to be a causative factor for BP. DPP4i-associated BP (DPP4i-BP) autoantibodies tend to target epitopes on non-NC16A regions of BP180, and the pathomechanism for the development of the unique autoantibodies remains unknown. To address the characteristics of DPP4i-BP autoantibodies in detail, we performed epitope analysis of 18 DPP4i-BP autoantibodies targeting the non-NC16A domains of BP180 using various domain-specific as well as plasmin-digested polypeptides derived from recombinant BP180. Firstly, Western blotting showed that only one DPP4i-BP serum reacted with the epitopes on the intracellular domain of BP180, and no sera reacted with the C-terminal domain of the molecule. In addition, only 2 DPP4i-BP sera reacted with BP230 as determined by enzyme-linked immunosorbent assay. Thus, DPP4i-BP autoantibodies were found to mainly target the non-NC16A mid-portion of the extracellular domain of BP. Interestingly, Western blotting using plasmin-digested BP180 as a substrate revealed that all of the DPP4i-BP sera reacted more intensively with the 97-kDa processed extracellular domain of BP180, which is known as the LABD97 autoantigen, than full-length BP180 did. All of the DPP4i-BP autoantibodies targeting the LABD97 autoantigen were IgG1, and IgG4 was observed to react with the molecule in only 7 cases (38.9%). In summary, the present study suggests that IgG1-class autoantibodies targeting epitopes on the processed extracellular domain of BP180, i.e., LABD97, are the major autoantibodies in DPP4i-BP.

Dipeptidyl peptidase IV inhibitor-associated bullous pemphigoid: a recently recognized autoimmune blistering disease with unique clinical, immunological and genetic characteristics

Bullous pemphigoid (BP) is an organ-specific autoantibody-mediated autoimmune blistering skin disorder that tends to affect the elderly. Tense blister formation associated with itchy urticarial erythema is clinically observed in BP, and subepidermal blister formation with eosinophilic infiltration is a histopathological characteristic. BP autoantibodies target two hemidesmosomal components in basal keratinocytes: BP180 and BP230. Anti-BP180 autoantibodies play major roles in blister formation. Although the autoantibody-mediated pathomechanism of blister formation has been extensively studied, little is known about how and why immune tolerance to BP180 may be broken in certain elderly individuals. Recently, BP has been increasingly reported in diabetes mellites (DM) patients receiving dipeptidyl peptidase-IV inhibitors (DPP4is), which are widely used anti-DM drugs. Pharmacovigilance and cohort studies have revealed that DPP4is, especially vildagliptin, teneligliptin, and linagliptin, are a potential risk factor for BP onset. Interestingly, it has been revealed that Japanese DPP4i-BP tends to show a non-inflammatory phenotype, with less erythema than normal BP, and that DPP4i-BP autoantibodies target distinct epitopes on BP180. In addition, human leukocyte antigen-DQB1*03:01 was identified as the major haplotype in Japanese DPP4i-BP. This review summarizes the latest understanding of the pathogenesis of BP, with a special focus on the recently recognized DPP4i-BP.

Analysis of patients with drug-induced pemphigoid using the Japanese Adverse Drug Event Report database

To clarify the incidence of drug-induced pemphigoid in Japan, we conducted a database search and analysis using the Japanese Adverse Drug Event Report database (JADER). Among the cases recorded in JADER between April 2004 and November 2017, we targeted "pemphigoid" and analyzed the patients' backgrounds, drug involvement, time of pemphigoid onset, outcomes and year reported. For cases where three or more drugs were reportedly involved, the signal index was calculated using the reporting odds ratio (ROR) method. The total number of reported pemphigoid cases was 769. Males accounted for 58% (446 cases) and patients over the age of 60 years accounted for 82% (630 cases). The most frequently reported causative drug was vildagliptin (288 cases), followed in order by sitagliptin phosphate hydrate (102 cases), teneligliptin hydrobromide hydrate (86 cases), linagliptin (64 cases) and furosemide (46 cases). For the 27 causative drugs, the safety signal was detected by the ROR method. The median time to onset tended to be long for these drugs. For vildagliptin with the largest reported number, the value was 508 days (range, 2-1871). Analysis of outcomes demonstrated recovery or improvement in 66.3% of cases. Analysis of the years in which reports had been published revealed that the number of pemphigoid cases has increased rapidly in recent years. Our survey was able to reveal useful data on the incidence of drug-induced pemphigoid. We expect that these results will aid the early detection and treatment of this condition.

Recent advances in the understanding and treatment of pemphigus and pemphigoid

Pemphigus and pemphigoid are characterized as autoimmune blistering diseases in which immunoglobulin G autoantibodies cause blisters and erosions of the skin or mucosa or both. Recently, understanding of the pathophysiology of pemphigus and pemphigoid has been furthered by genetic analyses, characterization of autoantibodies and autoreactive B cells, and elucidation of cell–cell adhesion between keratinocytes. For the management of pemphigus and pemphigoid, the administration of systemic corticosteroids still represents the standard treatment strategy; however, evidence of the efficacy of therapies not involving corticosteroids, such as those employing anti-CD20 antibodies, is increasing. The goal should be to develop antigen-specific immune suppression-based treatments.

The Role of Eosinophils in Bullous Pemphigoid: A Developing Model of Eosinophil Pathogenicity in Mucocutaneous Disease

Bullous pemphigoid (BP) is an autoimmune blistering disease which carries a significant mortality and morbidity. While historically BP has been characterized as an IgG driven disease mediated by anti-BP180 and BP230 IgG autoantibodies, developments in recent years have further elucidated the role of eosinophils and IgE autoantibodies. In fact, eosinophil infiltration and eosinophilic spongiosis are prominent features in BP. Several observations support a pathogenic role of eosinophils in BP: IL-5, eotaxin, and eosinophil-colony stimulating factor are present in blister fluid; eosinophils line the dermo-epidermal junction (DEJ) in the presence of BP serum, metalloprotease-9 is released by eosinophils at the site of blisters; eosinophil degranulation proteins are found on the affected basement membrane zone as well as in serum corresponding with clinical disease; eosinophil extracellular DNA traps directed against the basement membrane zone are present, IL-5 activated eosinophils cause separation of the DEJ in the presence of BP serum; and eosinophils are the necessary cell required to drive anti-BP180 IgE mediated skin blistering. Still, it is likely that eosinophils contribute to the pathogenesis of BP in numerous other ways that have yet to be explored based on the known biology of eosinophils. We herein will review the role of eosinophils in BP and provide a framework for understanding eosinophil pathogenic mechanisms in mucocutaneous disease.