Bullous pemphigoid induced by dipeptidyl peptidase-4 inhibitors. Eight cases with clinical and immunological characterization.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors have increasingly been identified as causative agents of bullous pemphigoid. The clinical and immunological characteristics of this pemphigoid variant are still unclear. The objective of our study was to analyze the clinical and immunological features of patients with pemphigoid induced by DPP-4 inhibitors. METHODS: All patients diagnosed with DPP-4 inhibitor-associated bullous pemphigoid at dermatology departments in three Spanish centers during the period 2013 to 2015 were included. ELISA assays for the NC16A domain of BP180 and BP230 were performed. Immunoblot studies using epidermal/dermal extracts and the C-terminal, NC16A and LAD-1 regions of BP180 were also carried out. RESULTS: A total of eight patients were identified (5 treated with vildagliptin, 2 with linagliptin, and one with sitagliptin). Of these, four presented the classical inflammatory phenotype of bullous pemphigoid and four a noninflammatory phenotype. The ELISA for BP180 (NC16A domain) was positive in six patients at diagnosis. Most patients reacted to more than one BP180 antigenic site (LAD-1 and/or C-terminal domain) on the immunoblot. Two patients showed no reaction against the NC16A domain of BP180 on either the ELISA or immunoblot but recognized either LAD-1 or both LAD-1 and the C-terminal domain. Only one of the NC16A-negative patients had a noninflammatory subtype of bullous pemphigoid. CONCLUSIONS: Patients with DPP-4 inhibitor-induced BP may present either an inflammatory or a noninflammatory phenotype of BP. IgG response against other BP180 regions different from the NC16A domain, such as LAD-1 and the C-terminal domain, could be pathogenically relevant to the onset of DPP-4 inhibitor-induced BP.

Epithelial antigenic specificities of circulating autoantibodies in mucosal lichen planus.

BACKGROUND: Mucosal lichen planus (LP) is an inflammatory disease of the mucous membranes of unknown origin. The antigen-specific autoantibodies or T cells responsible for this disease have not yet been established. OBJECTIVES: This study was designed to study the antigenic specificities of circulating antibodies in patients with mucosal LP and to review previous findings on this topic. METHODS: We tested a series of consecutive cases of mucosal LP in our clinic by enzyme-linked immunosorbent assay using desmoglein 3 (Dsg3) and BP180 fusion proteins. RESULTS: Three of 22 patients were positive for anti-NC16A antibodies. Interestingly, we found a middle-aged woman with severe disease with circulating anti-Dsg3 antibodies at high levels, typical of pemphigus vulgaris. Levels of these antibodies positively correlated with the severity of clinical manifestations. We failed to detect anti-desmoglein antibodies in any other patient in our series and in the literature review. CONCLUSIONS: Some patients with mucosal LP may present with circulating anti-BP180 antibodies at low levels. We also report the first case with positive anti-Dsg3 antibodies. The pathogenic relevance of these autoantibodies remains unknown.

Definitions and outcome measures for mucous membrane pemphigoid: recommendations of an international panel of experts.

Mucous membrane pemphigoid encompasses a group of autoimmune bullous diseases with a similar phenotype characterized by subepithelial blisters, erosions, and scarring of mucous membranes, skin, or both. Although knowledge about autoimmune bullous disease is increasing, there is often a lack of clear definitions of disease, outcome measures, and therapeutic end points. With clearer definitions and outcome measures, it is possible to directly compare the results and data from various studies using meta-analyses. This consensus statement provides accurate and reproducible definitions for disease extent, activity, outcome measures, end points, and therapeutic response for mucous membrane pemphigoid and proposes a disease extent score, the Mucous Membrane Pemphigoid Disease Area Index.

Management of autoimmune blistering diseases in Spain.

Autoimmune blistering diseases (AIBD) are relatively uncommon all over the world. Therefore most physicians and even dermatologists are generally unfamiliar with their diagnosis and treatment. In Spain there are very few dermatologists and dermatology clinics specialized in AIBD. This article provides an overview of the management of AIBD in Spain at the present time.

Isolated conjunctival lichen planus: a diagnostic challenge.

BACKGROUND: Lichen planus is a common inflammatory autoimmune condition of unknown etiology that commonly affects the skin and mucous membranes. Isolated ocular lichen planus is an extremely rare presentation that most commonly involves the eyelids, conjunctiva, and cornea, leading to severe scarring, and is clinically indistinguishable from other causes of cicatricial conjunctivitis. OBSERVATIONS: A 79-year-old man complained of a chronic keratoconjunctivitis refractory to multiple topical treatments. Slit-lamp examination revealed diffuse bilateral conjunctival hyperemia, subepithelial fibrosis, and symblepharon, with a marked shortening of the lower conjunctival fornix. There were no other skin or mucosal lesions. Hematoxylin-eosin staining revealed acanthosis, focal thickening of the basement membrane, and a dense subepithelial mononuclear infiltrate. Direct immunofluorescence demonstrated a linear shaggy fibrinogen deposition along the basement membrane, suggestive of lichen planus. Ultrastructural examination revealed a marked widening of the epithelium-lamina propria interphase, with prominent fragmentation, reduplication, and reticulation of the lamina densa of the basement membrane. The patient was successfully treated with systemic immunosuppressive agents. CONCLUSIONS: Isolated conjunctival lichen planus is an exceptional and severe cause of cicatricial conjunctivitis. Distinguishing this unusual presentation from other inflammatory diseases with conjunctival involvement is crucial to initiate an appropriate therapy early to avoid irreversible damage of the visual function.

Dermoscopic and reflectance confocal microscopic features of exogenous ochronosis.

BACKGROUND: Exogenous ochronosis presents as an acquired asymptomatic hyperpigmentation on photoexposed areas, predominantly over bony prominences, and is caused by the topical application of several skin-lightening agents. OBSERVATIONS: We describe a 63-year-old Hispanic woman who developed exogenous ochronosis lesions on her face after using topical bleaching creams containing hydroquinone, 2% to 3%, and oxybenzone, 2%, for several years. Dermoscopy revealed irregular brown-gray globular, annular, and arciform structures that corresponded to focal deposition of ochronotic pigment on the dermis. These deposits correlated with multiple banana-shaped nonrefractile structures seen using reflectance confocal microscopy. Histopathologic sections revealed the deposition of a banana-shaped, yellow to brown material in the papillary and middle dermis. Ultrastructural examination revealed an amorphous electron-dense material mostly located in the core of elastic fibers and also in smaller amounts in the interstitium with prominent degenerative changes in the elastic fibers. A good correlation was observed between the results of both noninvasive techniques and the diagnostic histologic features of this condition. CONCLUSIONS: We characterized by means of dermoscopy, reflectance confocal microscopy, and electronic microscopy a case of exogenous ochronosis. To our knowledge, this is the first description of reflectance confocal microscopic findings in this condition. Dermoscopy and reflectance confocal microscopy are proved to be useful noninvasive techniques for the diagnosis of this pigmentary disorder.

Correlation of immunological profile with phenotype and disease outcome in pemphigus.

There has been no previous clinical-immunological study of pemphigus in Spain. The aim of this study was to perform a retrospective analysis of pemphigus patients who had been followed for a period of 18 years in our centre. We characterized the autoantibody response, compared diagnostic assays and correlated the immunobiological data with phenotype and prognosis. Clinical, epidemiological and immunopathological data were collected from 40 patients. Patients sera were characterized by indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA). Epidemiological and clinical findings were comparable to other series. Mortality during follow-up was 0% and 6% in pemphigus foliaceus and vulgaris, respectively. Importantly, higher indirect immunofluorescence titres and anti-desmoglein 3 ELISA values of samples from untreated patients correlated significantly with a potentially worse clinical course. Moreover, there was a positive correlation between indirect immunofluorescence titres and anti-desmoglein 3 ELISA levels in pemphigus vulgaris patients. Based on our findings, initial high anti-desmoglein 3 antibodies in pemphigus patients correlate with a more adverse prognosis, which raises the question as to whether a more aggressive initial therapy is indicated in patients with this immunological pattern.

IgG4 autoantibodies induce dermal-epidermal separation.

Bullous pemphigoid (BP) is a sub-epidermal autoimmune blistering disease associated with autoantibodies to the dermal-epidermal junction (DEJ). Patients' autoantibodies induce dermal-epidermal separation when co-incubated with cryosections of human skin and leucocytes from healthy volunteers. IgG autoantibodies trigger complement and/or leucocyte activation resulting in specific pathology in several autoimmune conditions. In these diseases, IgG1 and IgG3 isotypes, but not the IgG4 subclass, are thought to trigger inflammatory pathways resulting in tissue damage. The capacity of IgG4 autoantibodies to mediate tissue damage has not yet been demonstrated. In this study, we isolated IgG1 and IgG4 autoantibodies from bullous pemhigoid patients'serum and analysed their blister-inducing potential in our cryosection assay. As expected, complement-fixing IgG1 autoantibodies induced sub-epidermal splits in this experimental model. Purified IgG4 did not fix complement, but, interestingly, like IgG1, activated leucocytes and induced dermal-epidermal separation. The potential of IgG4 autoantibodies to induce Fc-dependent dermal-epidermal separation was significantly lower compared to IgG1. Our results demonstrate that IgG4 autoantibodies are able to activate leucocytes and point to a hitherto less recognized function of IgG4. Moreover, for the first time, we clearly demonstrate that BP IgG4 autoantibodies have the capacity to induce leucocyte-dependent tissue damage.

Atypical pemphigus: discordance between clinicopathological findings and the antigenic profile in four cases.

BACKGROUND: The diagnosis of pemphigus vulgaris and pemphigus foliaceus is usually based on clinical, histological, and immunofluorescence (IF) findings. In recent years, the antigenic profile of both diseases has been further defined by immunobiochemical techniques (ELISA, immunoblot, and immunoprecipitation). METHODS: A retrospective study of 40 pemphigus patients was performed to determine the clinical, histological, and antigenic profile in patients with pemphigus followed at our Department. Charts review, clinical data, histological and IF findings, and antigenic analysis by ELISA were performed in all patients. RESULTS: In most patients, there was a perfect correlation between the clinical and histological findings and their antigenic profile. In four patients (10%), clinicopathological features and antigenic findings were discordant. CONCLUSIONS: The antigenic profiles in pemphigus do not always correlate with the clinical diagnosis. Therefore, clinical and histological features should be considered as the mainstay for the diagnosis of pemphigus.

Immunoadsorption against two distinct epitopes on human type XVII collagen abolishes dermal-epidermal separation induced in vitro by autoantibodies from pemphigoid gestationis patients.

Pemphigoid gestationis (PG) is a subepidermal autoimmune blistering disease characterized by self-reactive T and B cells specific for the transmembrane hemidesmosomal protein type XVII collagen/BP180. Major T and B cell epitopes are located within the immunodominant 16th non-collagenous domain A (NC16A) of type XVII collagen. The aim of the present study was to map the pathogenically relevant epitopes targeted by blister-inducing patients' autoantibodies. For this purpose, we used an in vitro model of autoantibody-induced leukocyte-dependent dermal-epidermal separation. Pre-adsorption against a recombinant form of the NC16A region abolished the blister-inducing potential of autoantibodies from all PG patients. Using overlapping synthetic peptides, we demonstrated that PG autoantibodies bind to two defined epitopes within the NC16A region (aa 500-514 and aa 511-523). Importantly, pre-adsorption using an affinity matrix containing these epitopes completely abolished dermal-epidermal separation induced by PG autoantibodies. This study identifies the epitopes relevant for blister induction in PG and should facilitate the development of an antigen-specific immunoadsorption therapy for this disease.