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Background: Immunoglobulin G (IgG) levels are maintained by the IgG-recycling neonatal Fc-receptor (FcRn). Pemphigus vulgaris and pemphigus foliaceus are debilitating autoimmune disorders triggered by IgG autoantibodies against mucosal and epidermal desmogleins. Recently, a phase 2 clinical trial (NCT03334058; https://clinicaltrials.gov/NCT03334058) was completed in participants with pemphigus using efgartigimod, an FcRn inhibitor, in combination with prednisone. Efgartigimod demonstrated an early effect on diease activity and was well tolerated. In addition to the safety and efficacy assessment, clinical trials present an opportunity to gain more insights into the mechanism of disease, the mode of action of treatment, and potential for corticosteroid-sparing activity. Objective: The aim of our study was to assess the impact of FcRn antagonism by efgartigimod on immunological parameters known to be directly involved in pemphigus pathology, such as cellular and serological responses. Methods: We investigated total and antigen-specific IgG subclass level kinetics during and after treatment, assessed antigen-specific B-cell responses, followed T- and B-cell immunophenotypes, and analyzed how different immunophenotypes link to clinical response. Results: Treatment resulted in reduction of total IgG as well as autoreactive IgG antibody levels. Surprisingly, unlike total IgG and vaccine- or natural-infection-elicited IgG, which returned to baseline levels after stopping efgartigimod treatment, autoreactive antibody levels remained low in several study participants. Efgartigimod showed no effect on total leukocytes, neutrophils, monocytes, or lymphocytes in patients treated with extended efgartigimod therapy. Intriguingly, antigen-specific analyses revealed a loss of desmoglein-specific B cells in several participants responding to efgartigimod, in line with prolonged reduction of pathogenic IgG levels. Conclusions: Efgartigimod treatment of participants with pemphigus improved their conditions and exerted an immunomodulatory effect beyond the blockade of IgG recycling. Further studies in larger populations with an appropriate placebo control are needed to confirm these potentially important observations to establish long-term clinical responses in autoimmune diseases. [ABSTRACT FROM AUTHOR]

BackgroundImmunoglobulin G (IgG) levels are maintained by the IgG-recycling neonatal Fc-receptor (FcRn). Pemphigus vulgaris and pemphigus foliaceus are debilitating autoimmune disorders triggered by IgG autoantibodies against mucosal and epidermal desmogleins. Recently, a phase 2 clinical trial (NCT03334058; https://clinicaltrials.gov/NCT03334058) was completed in participants with pemphigus using efgartigimod, an FcRn inhibitor, in combination with prednisone. Efgartigimod demonstrated an early effect on diease activity and was well tolerated. In addition to the safety and efficacy assessment, clinical trials present an opportunity to gain more insights into the mechanism of disease, the mode of action of treatment, and potential for corticosteroid-sparing activity.ObjectiveThe aim of our study was to assess the impact of FcRn antagonism by efgartigimod on immunological parameters known to be directly involved in pemphigus pathology, such as cellular and serological responses.MethodsWe investigated total and antigen-specific IgG subclass level kinetics during and after treatment, assessed antigen-specific B-cell responses, followed T- and B-cell immunophenotypes, and analyzed how different immunophenotypes link to clinical response.ResultsTreatment resulted in reduction of total IgG as well as autoreactive IgG antibody levels. Surprisingly, unlike total IgG and vaccine- or natural-infection-elicited IgG, which returned to baseline levels after stopping efgartigimod treatment, autoreactive antibody levels remained low in several study participants. Efgartigimod showed no effect on total leukocytes, neutrophils, monocytes, or lymphocytes in patients treated with extended efgartigimod therapy. Intriguingly, antigen-specific analyses revealed a loss of desmoglein-specific B cells in several participants responding to efgartigimod, in line with prolonged reduction of pathogenic IgG levels.ConclusionsEfgartigimod treatment of participants with pemphigus improved their conditions and exerted an immunomodulatory effect beyond the blockade of IgG recycling. Further studies in larger populations with an appropriate placebo control are needed to confirm these potentially important observations to establish long-term clinical responses in autoimmune diseases.

Pemphigus herpetiformis is one of the less common forms of pemphigus, first introduced by Jabłońska and colleagues in 1975. This autoimmune bullous disease combines the clinical features of dermatitis herpetiformis and the immunologic characteristics of pemphigus. The target autoantigen is usually desmoglein 1 (or less frequently desmoglein 3), although recently it has become increasingly obvious that patients with pemphigus herpetiformis also demonstrate autoantibodies against desmocollin. Here, we summarize reported cases of pemphigus herpetiformis and describe current knowledge considering epidemiology, clinical manifestations, histologic findings, immunopathology, pathophysiologic concepts, associated diseases, and treatment of this rare disorder. [Copyright &y& Elsevier]

Background: Few studies have evaluated pemphigus treatments according to the definitions of the consensus statement. Prognostic factors for complete remission off therapy (CRoffT) remain unknown. Objective: We sought to assess the rate of CRoffT in patients with pemphigus treated with different regimens. Methods: In all, 134 patients with pemphigus were included in a retrospective, multicenter study. Primary end point was the rate of CRoffT. Prognostic factors for CRoffT were determined using univariate and multivariate analyses. Results: Eighty patients with pemphigus vulgaris, 47 with pemphigus foliaceus, and 7 with paraneoplastic pemphigus were included. Mean age was 60 ± 18 years. Patients were treated either with medium (≤0.5 mg/kg/d) (n = 32) or high (≥1 mg/kg/d) (n = 59) doses of prednisone, or without systemic corticosteroids (n = 43). Mean follow-up was 77 ± 64 months. In all, 68 patients (50.7%) achieved CRoffT (95% confidence interval 42.3%-59.2%) after a mean treatment duration of 36 ± 39 months, including 47 of 80 patients with pemphigus vulgaris (58.7%) and 21 of 47 with pemphigus foliaceus (44.7%). Main prognostic factors for CRoffT were initial mucosal involvement (hazard ratio 2.2; 95% confidence interval 1.05-4.58; P = .036) and younger age (<61 years) (hazard ratio 2.5; 95% confidence interval 1.18-5.12; P = .0167). The rate of long-lasting CRoffT was 44%, with a mean follow-up after treatment withdrawal of 59 ± 50 months. Limitations: This was a retrospective study. Conclusion: The rate of CRoffT was 51%. Patients with pemphigus vulgaris were more likely to achieve CRoffT than those with pemphigus foliaceus. [Copyright &y& Elsevier]

Abstract: Background: We recently reported that the autoantibodies of anti-p200 pemphigoid sera react with laminin γ1 and renamed this entity as anti-laminin γ1 pemphigoid. However, it has not been clarified whether the anti-laminin γ1 autoantibodies, particularly those to the C-terminal integrin binding site, affect the dermoepidermal junction and cause subepidermal blisters. Objective: The aim of this study was to develop animal models for anti-laminin γ1 pemphigoid. Methods: We attempted to produce two mouse models for anti-laminin γ1 pemphigoid; (1) a passive transfer model: injection of rabbit IgG to shorter bacterial recombinant protein of the murine laminin γ1 C-terminal 107 amino acids, and (2) an active disease model: direct immunization to mice with this recombinant protein. Results: Immunoblotting revealed that 70% of patient sera reacted with the shorter recombinant protein of human laminin γ1 C-terminus. In the passive transfer model, rabbit IgG to the murine laminin γ1 C-terminus was deposited, without C3 deposition, at the epidermal basement membrane zone. In contrast, in the active disease model, direct immunofluorescence of mouse skin sections showed no deposition of either murine IgG or C3. Blister formation was not seen in either model both phenotypically and histopathologically. Conclusion: In the two different mouse animal models for anti-laminin γ1 pemphigoid, although rabbit IgG to the recombinant laminin γ1 C-terminus bound to the epidermal basement membrane zone in passive transfer model, no obvious blister formation was seen. To reproduce skin lesions in mouse models for anti-laminin γ1 pemphigoid, further improvement should be needed. [Copyright &y& Elsevier]

Pemphigus vulgaris (PV) is an autoimmune blistering disease of the skin of unknown etiology. While various environmental factors have been implicated as triggering agents, HLA association is probably the most important predisposing factor. The aim of this review is to highlight the association of HLA with pemphigus vulgaris. In addition, we present recent results showing a possible association with the nonclassical HLA-G antigen. [Copyright &y& Elsevier]

Systemic vasculitis represents a broad range of diseases characterized by the presence of blood vessel inflammation. Immunosuppressive therapy forms the foundation of treatment for almost all forms of systemic vasculitis. Newer agents such as mycophenolate mofetil, rituximab and tumour necrosis factor-α inhibitors are finding new indications in the therapy of conditions such as systemic lupus erythematosus, idiopathic thrombocytopenic purpura, skin vasculitis, cytoplasmic antineutrophil antibodies-positive vasculitis, sarcoidosis, ocular inflammation, nephritis, inflammatory bowel disease and Takayasu’s arteritis. However, older agents such as methotrexate, cyclophosphamide and interferon-α are still being explored for newer, more effective and less toxic indications in conditions such as giant cell arteritis and cutaneous polyarteritis nodosa. [Copyright &y& Elsevier]

The aim of this study was to generate a recombinant protein to represent the entire extracellular domain of canine desmoglein 1 (Dsg1), a desmosomal cell–cell adhesion molecule, by the baculovirus expression system. Cotransfection of a baculovirus transfer vector containing the cDNA for the entire extracellular domain of canine Dsg1 with baculovirus DNA into insect cells resulted in the secretion of soluble canine Dsg1 into insect culture supernatants. Immunoreactivity of 11 human pemphigus foliaceus (PF) sera against the cell surface of canine keratinocytes was completely removed when the sera were preincubated with the canine Dsg1 baculoprotein. This recombinant canine Dsg1 produced by baculovirus shares the major epitopes of the authentic canine Dsg1 recognized by human PF sera, and will be useful in studying the molecular pathophysiological mechanisms in PF and impetigo in canine patients. [Copyright &y& Elsevier]