Pemphigus vulgaris (PV) is an autoimmune epidermal blistering disease in which autoantibodies (IgG) are directed against the desmosomal cadherin desmoglein 3. To better understand how PV IgG alters desmosome morphology and function in vivo, biopsies from patients with PV were analyzed by structured illumination microscopy, a form of superresolution fluorescence microscopy. In patient tissue, desmosomal proteins were aberrantly clustered and patient IgG colocalized with markers for lipid rafts and endosomes. Additionally, steady-state levels of desmoglein 3 were decreased and desmosomes were reduced in size in patient tissue. Desmosomes at blister sites were occasionally split, with PV IgG decorating the extracellular faces of split desmosomes. Desmosome splitting was recapitulated in vitro by exposing cultured keratinocytes both to PV IgG and to mechanical stress, demonstrating that splitting at the blister interface in patient tissue is due to compromised desmosomal adhesive function. These findings indicate that desmoglein 3 clustering and endocytosis are associated with reduced desmosome size and adhesion defects in tissue of patients with PV. Further, this study reveals that superresolution optical imaging is a powerful approach for studying epidermal adhesion structures in normal and diseased skin.

Background Several European countries recently developed international diagnostic and management guidelines for pemphigus, which have been instrumental in the standardization of pemphigus management. Objective We now present results from a subsequent Delphi consensus to broaden the generalizability of the recommendations. Methods A preliminary survey, based on the European Dermatology Forum and the European Academy of Dermatology and Venereology guidelines, was sent to a panel of international experts to determine the level of consensus. The results were discussed at the International Bullous Diseases Consensus Group in March 2016 during the annual American Academy of Dermatology conference. Following the meeting, a second survey was sent to more experts to achieve greater international consensus. Results The 39 experts participated in the first round of the Delphi survey, and 54 experts from 21 countries completed the second round. The number of statements in the survey was reduced from 175 topics in Delphi I to 24 topics in Delphi II on the basis of Delphi results and meeting discussion. Limitations Each recommendation represents the majority opinion and therefore may not reflect all possible treatment options available. Conclusions We present here the recommendations resulting from this Delphi process. This international consensus includes intravenous CD20 inhibitors as a first-line therapy option for moderate-to-severe pemphigus.

Pemphigus vulgaris (PV) is an autoimmune epidermal blistering disease in which autoantibodies (IgG) are directed against the desmosomal cadherin desmoglein 3. To better understand how PV IgG alters desmosome morphology and function in vivo, biopsies from patients with PV were analyzed by structured illumination microscopy, a form of superresolution fluorescence microscopy. In patient tissue, desmosomal proteins were aberrantly clustered and patient IgG colocalized with markers for lipid rafts and endosomes. Additionally, steady-state levels of desmoglein 3 were decreased and desmosomes were reduced in size in patient tissue. Desmosomes at blister sites were occasionally split, with PV IgG decorating the extracellular faces of split desmosomes. Desmosome splitting was recapitulated in vitro by exposing cultured keratinocytes both to PV IgG and to mechanical stress, demonstrating that splitting at the blister interface in patient tissue is due to compromised desmosomal adhesive function. These findings indicate that desmoglein 3 clustering and endocytosis are associated with reduced desmosome size and adhesion defects in tissue of patients with PV. Further, this study reveals that superresolution optical imaging is a powerful approach for studying epidermal adhesion structures in normal and diseased skin.

Autoimmune blistering skin diseases (AIBDs) comprise a group of immune-mediated disorders characterized by the presence of autoantibodies directed against cutaneous epitopes resulting in frequent blister formation. Associations between the most common AIBDs, pemphigus, and pemphigoid and other inflammatory or autoimmune diseases have been described, so-called autoimmune diathesis.1 This diathesis has been well described with regard to pemphigoid and concomitant neurologic inflammatory or autoimmune diseases such as Alzheimer’ disease, Parkinson’ disease, and multiple sclerosis.2,3 These neurocutaneous associations are hypothesized to be, at least in part, caused by autoantibodies directed at both cutaneous and neurologic tissues. Due to their shared embryologic origin, several receptor binding domains are co-expressed across both dermatologic and neurologic tissues (eg, BP180, BP230). Cross-reactive antibodies are believed to play a role in mediating the clinical sequelae related to the skin; although the role in various neurological diseases is still unclear, with circulating anti-BP180, 230 autoantibodies reported in patients with Alzheimer disease and Parkinson disease.4,5

Pemphigus vulgaris (PV) is an autoimmune disease characterized by blistering sores on skin and mucosal membranes, caused by autoantibodies primarily targeting the cellular adhesion protein, desmoglein-3 (Dsg3). To better understand how Dsg3-specific autoantibodies develop and cause disease in humans, we performed a cross-sectional study of PV patients before and after treatment to track relevant cellular responses underlying disease pathogenesis, and we provide an in-depth analysis of two patients by generating a panel of mAbs from single Dsg3-specific memory B cells (MBCs). Additionally, we analyzed a paired sample from one patient collected 15-months prior to disease diagnosis. We find that Dsg3-specific MBCs have an activated phenotype and show signs of ongoing affinity maturation and clonal selection. Monoclonal antibodies (mAbs) with pathogenic activity primarily target epitopes in the extracellular domains EC1 and EC2 of Dsg3, though they can also bind to the EC4 domain. Combining antibodies targeting different epitopes synergistically enhances in vitro pathogenicity.

Dupilumab is a fully human monoclonal antibody that functions as an interleukin (IL) 4α receptor antagonist, inhibiting the activity of both IL-4 and IL-13, drivers of T helper 2 mediated inflammation. Although injection-site reactions are the most reported side effect, there have been several reported cases of adverse dermatologic reactions, including facial and neck erythema.1,2 We present a case of a patient with severe eosinophilic asthma and chronic sinusitis with nasal polyps in whom drug-induced erythema nodosum (EN) developed after 8 weeks of dupilumab therapy.

Bullous pemphigoid (BP) is an autoimmune blistering disease resulting in pruritus and cutaneous blistering. Longitudinal studies characterizing the disease course of patients with BP on conventional therapy are lacking. We sought to characterize the changes in disease activity and pruritus of patients with BP on standard-of-care treatments. We conducted a retrospective cohort study on patients with BP on standard-of-care therapy. Generalized Estimating Equations were used to estimate the mean and standard errors for Bullous Pemphigoid Disease Activity Index (BPDAI) total activity score, BPDAI pruritus component score, and anti-BP180 autoantibody levels (BP180) over time. A total of 80 patients with BP showed consistent reductions in BPDAI total activity score and BPDAI pruritus component score, with a nadir at 4 months. BP180 decreased over time, with the largest reductions at 6 and 9 months. Median partial/complete remission was at 6.7 months, with relapses at a median time of 15.9 months. Receiving operating characteristic analysis determined an optimal BPDAI total activity score cutoff of 3.3 to discriminate partial/complete remission incidence (area under the curve = 0.895, sensitivity = 0.844, specificity = 0.78). In conclusion, in patients with BP on standard-of-care therapy, a natural course of BPDAI total activity score and BPDAI pruritus component score over time was comprehensively projected. BPDAI ≤ 3.3 was associated with partial/complete remission. These results provide reference data to guide future clinical trial design for BP.

Rituximab is a therapeutic anti-CD20 monoclonal antibody widely used to treat B cell lymphoma and autoimmune diseases, such as rheumatic arthritis, systemic lupus erythematosus, and autoimmune blistering skin diseases (AIBD). While rituximab fully depletes peripheral blood B cells, it remains unclear whether some preexisting B cell memory to pathogens or vaccines may survive depletion, especially in lymphoid tissues, and if these memory B cells can undergo homeostatic expansion during recovery from depletion. The limited data available on vaccine efficacy in this setting have been derived from rituximab-treated patients receiving concomitant chemotherapy or other potent immunosuppressants. Here, we present an in-depth analysis of seasonal influenza vaccine responses in AIBD patients previously treated with rituximab, who generally did not receive additional therapeutic interventions. We found that, despite a lack of influenza-specific memory B cells in the blood, patients mount robust recall responses to vaccination, comparable to healthy controls, both at a cellular and a serological level. Repertoire analyses of plasmablast responses suggest that they likely derive from a diverse pool of tissue-resident memory cells, refractory to depletion. Overall, these data have important implications for establishing an effective vaccine schedule for AIBD patients and the clinical care of rituximab-treated patients in general and contribute to our basic understanding of maintenance of normal and pathogenic human B cell memory.

Acute systemic lupus erythematosus (SLE) courses with surges of antibody-secreting cells (ASCs) whose origin, diversity and contribution to serum autoantibodies remain unknown. Here, deep sequencing, proteomic profiling of autoantibodies and single-cell analysis demonstrated highly diversified ASCs punctuated by clones expressing the variable heavy-chain region V<inf>H</inf>4-34 that produced dominant serum autoantibodies. A fraction of ASC clones contained autoantibodies without mutation, a finding consistent with differentiation outside the germinal centers. A substantial ASC segment was derived from a distinct subset of newly activated naive cells of considerable clonality that persisted in the circulation for several months. Thus, selection of SLE autoreactivities occurred during polyclonal activation, with prolonged recruitment of recently activated naive B cells. Our findings shed light on the pathogenesis of SLE, help explain the benefit of agents that target B cells and should facilitate the design of future therapies.