Evidence for a role of extracellular heat shock protein 70 in epidermolysis bullosa acquisita.

Heat shock protein 90 (Hsp90) and Hsp70 are chaperones implicated in different inflammatory disorders, given their property to impact innate and adaptive immune responses. Here, we determined the so far unknown role of extracellular Hsp70 in epidermolysis bullosa acquisita (EBA), an anti-type VII collagen autoantibody-mediated blistering dermatosis. The in vivo pathophysiological relevance of extracellular Hsp70 was demonstrated in an anti-type VII collagen antibody transfer-induced EBA mouse model in which elevated blood levels of this chaperone were recorded. We found that Hsp70-treated mice had a more intense clinical disease severity compared to controls that were paralleled by increased levels of cutaneous matrix metalloproteinase 9 and plasma hydrogen peroxide. The latter finding was confirmed in an independent reactive oxygen species release assay using EBA-specific immune complexes combined with recombinant Hsp70. Finally, cell culture experiments using human naive peripheral blood mononuclear cells (PBMC) revealed that extracellular Hsp70 stimulated the secretion of the T cell-derived pro-inflammatory cytokines IL-6 and IL-8. This work extends knowledge about the role of Hsps in autoimmune bullous diseases, suggesting that extracellular Hsp70 represents a pathophysiological factor and potential treatment target in EBA.

Immunoglobulin and Complement Immunohistochemistry on Paraffin Sections in Autoimmune Bullous Diseases: A Systematic Review and Meta-analysis.

ABSTRACT: Immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded tissue has been proposed as a potential tool in the diagnosis of autoimmune bullous diseases (AIBDs) in lieu of standard direct immunofluorescence (DIF) microscopy. To comprehensively determine the diagnostic accuracy of immunoglobulin and complement IHC for diagnosis of AIBDs, we conducted a systematic review and multivariate Bayesian model-based meta-analysis of the literature. Quality and heterogeneity assessment of studies was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklist and the I2 index, respectively. Electronic searches using PubMed from April 1964 to July 2020 identified 14 articles meeting predetermined inclusion and exclusion criteria. Median sensitivities with 95% credible intervals in pemphigus and pemphigoid were 0.24 (0.01-0.89) and 0.22 (0.02-0.77) with immunoglobulin G (IgG), 0.77 (0.39-0.95) and 0.25 (0.02-0.85) with IgG4, 0.11 (0.02-0.32) and 0.86 (0.56-0.98) with C3d, and 0.84 (0.56-0.97) and 0.75 (0.37-0.94) with C4d, respectively. Specificities were 1.00 (0.00-1.00) with IgG, 0.98 (0.89-1.00) with IgG4, 0.99 (0.97-1.00) with C3d, and 0.99 (0.97-1.00) with C4d. The risk of bias and heterogeneity among studies was a serious problem, decreasing the level of evidence. Our work suggests that, in selected cases, paraffin-based IHC may be a helpful procedure to screen for AIBDs, especially when specialized laboratories and/or biopsy specimens for DIF do not exist. Nevertheless, more studies with a refined quality design are needed to explore the true usefulness of this diagnostic method in AIBDs.

Pemphigus.

Pemphigus consists of a group of rare and severe autoimmune blistering diseases mediated by pathogenic autoantibodies mainly directed against two desmosomal adhesion proteins, desmoglein (Dsg)1 and Dsg3 (also known as DG1 and DG3), which are present in the skin and surface-close mucosae. The binding of autoantibodies to Dsg proteins induces a separation of neighbouring keratinocytes, in a process known as acantholysis. The two main pemphigus variants are pemphigus vulgaris, which often originates with painful oral erosions, and pemphigus foliaceus, which is characterised by exclusive skin lesions. Pemphigus is diagnosed on the basis of either IgG or complement component 3 deposits (or both) at the keratinocyte cell membrane, detected by direct immunofluorescence microscopy of a perilesional biopsy, with serum anti-Dsg1 or anti-Dsg3 antibodies (or both) detected by ELISA. Corticosteroids are the therapeutic mainstay, which have recently been complemented by the anti-CD20 antibody rituximab in moderate and severe disease. Rituximab induces complete remission off therapy in 90% of patients, despite rapid tapering of corticosteroids, thus allowing for a major corticosteroid-sparing effect and a halved number of adverse events related to corticosteroids.

[Immunoadsorption in dermatology]. / Immunadsorption in der Dermatologie.

Autoimmmune bullous diseases are mediated by pathogenetically relevant autoantibodies against components of the epidermis and/or superficial mucous membranes (in pemphigus) and structural proteins of the dermal-epidermal junction (in pemphigoid diseases). Using immunoadsorption (IA), an already well-established procedure in cardiac and rheumatic disorders, antibodies can be removed from the plasma. At present, most data on the adjuvant use of IA in dermatology are derived from patients with severe and/or refractory pemphigus vulgaris or pemphigus foliaceus and also from patients with pemphigoid diseases. Additionally, in the last few years different protocols for IA in patients with severe atopic dermatitis and elevated total serum IgE levels have been published. While panimmunoglobulin adsorbers are mainly used in dermatology, an IgE-specific adsorber has been used in some patients with atopic dermatitis and in the future, antigen-specific adsorbers are to be expected that will enable the specific reduction of autoantibodies.

Adjuvant treatment of severe/refractory bullous pemphigoid with protein A immunoadsorption.

BACKGROUND: While depletion of circulating autoantibodies using immunoadsorption (IA) is an established therapeutic approach in patients with pemphigus vulgaris, IA has only sporadically been used in other autoimmune bullous disorders. Although bullous pemphigoid (BP) usually responds well to topical and systemic corticosteroids, rapid depletion of serum autoantibodies may be an effective adjuvant treatment option in patients with severe and/or refractory disease. PATIENTS AND METHODS: Case series of 20 patients (13 women, 7 men; mean age 78.6 years; range 56-94 years) with severe or refractory BP. In addition to oral prednisolone (0.25-0.5 mg/kg/day), dapsone (1.0-1.5 mg/kg/day), and clobetasol propionate 0.05 % ointment (lesional application, twice daily), treatment consisted of protein A IA (three sessions on consecutive days). The mean follow-up period was 33.6 months (1-84 months). RESULTS: The majority of patients showed a rapid and sustained response. One month after treatment, eight patients (42 %; 19 patients were included in the follow-up) were in complete remission; at the last follow-up visit (after 1 to 84 months), that number was 13 (68 %). Not only was there an initial drop in anti-BP180 autoantibodies (by 92 %), the effect also continued after one and three months, with mean autoantibody levels at 26 % and 13 % of baseline, respectively (p < 0.001). Both previously treated and treatment-naive patients showed a significant reduction in anti-BP180NC16A antibody levels throughout the observation period. Adverse events occurred in 13 of the 20 patients (65 %). Three were severe of which two were likely or probably related to IA. CONCLUSION: Immunoadsorption is an effective adjuvant treatment option for (the usually elderly) patients with severe and/or refractory BP.

Adjuvante Behandlung des schweren/refraktären bullösen Pemphigoids mit Protein-A-Immunadsorption.

HINTERGRUND: Mittels Immunadsorption (IA) können Immunglobuline und Immunkomplexe aus dem Plasma entfernt werden. Während dieses therapeutische Verfahren beim Pemphigus vulgaris bereits etabliert ist, wird es bei anderen blasenbildenden Autoimmundermatosen bislang nur sporadisch eingesetzt. Das bullöse Pemphigoid (BP) spricht zwar meist gut auf eine Therapie mit topischen und systemischen Kortikosteroiden an, jedoch könnte bei Patienten mit ausgedehnten Läsionen oder bei einem Rezidiv die rasche Reduktion der pathogenen Autoantikörper eine effektive adjuvante Therapie darstellen. PATIENTEN UND METHODIK: Fallserie mit 20 Patienten (13 Frauen, 7 Männer; mittleres Alter 78,6 Jahre; 56-94 Jahre) mit schwerem oder refraktärem BP, die zusätzlich zur Basistherapie bestehend aus Prednisolon (0,25-0,5 mg/kg/d), Dapson (1,0-1,5 mg/kg/d) und Clobetasolpropionat 0,05 % Salbe (läsional 2 x/d) mit Protein-A-IA (3 IAs an aufeinander folgenden Tagen) behandelt wurden. Die durchschnittliche Nachbeobachtungszeit betrug 33,6 Monate (1-84 Monate). ERGEBNISSE: Bei der Mehrzahl der Patienten zeigte sich ein rascher und langandauernder Therapieeffekt. Nach einem Monat befanden sich acht Patienten (von 19 nachbeobachteten, 42 %) und zum Zeitpunkt des letzten Kontakts (nach 1-84 Monaten) 13 Patienten (68 %) in kompletter Remission. Die Anti-BP180-Autoantikörper wurden nicht nur initial (um 92 %) gesenkt, sondern lagen auch nach ein und drei Monaten im Mittel bei 26 % und 13 % des Wertes vor Therapiebeginn (p < 0,001). Bei Differenzierung in vortherapierte bzw. therapienaive Patienten zeigten sich in beiden Subgruppen signifikante Absenkungen der Anti-BP180NC16A-Antikörper-Spiegel zu allen Zeitpunkten. Unerwünschte Ereignisse traten bei dreizehn (65 %) der 20 Patienten auf, Drei der Ereignisse waren schwer und zwei davon wahrscheinlich oder möglicherweise in Zusammenhang mit der IA. SCHLUSSFOLGERUNGEN: Die IA ist eine effektive adjuvante Therapieoption bei den in aller Regel älteren Patienten mit einem schweren und/oder therapierefraktären BP.

Analysis of serum markers of cellular immune activation in patients with bullous pemphigoid.

Experimental models of bullous pemphigoid (BP), the most frequent subepidermal autoimmune bullous disease, revealed that the immune response leading to blister formation represents an incompletely understood complex process involving different inflammatory cells. In contrast to previous reports commonly focusing on limited molecular and cellular phenotypes of the disease, the aim of this study was to investigate a broad spectrum of markers of cellular immune activation in patients with BP. We found that serum levels of soluble CD4, myeloperoxidase, S100A12, eosinophil cationic protein and soluble P-selectin were significantly elevated in patients with active BP compared with normal controls. Mast cell tryptase and neopterin serum levels significantly decreased at the time of clinical remission of the patients. Additionally, serum concentrations of soluble IL-2 receptor, mast cell tryptase and soluble P-selectin were significantly associated with levels of circulating anti-BP180 autoantibodies. Our findings confirm and extend previous reports suggesting some concomitant involvement of a panel of molecules representative for a wide spectrum of cellular players (T cells, mast cells, neutrophils, eosinophils, macrophages and platelets) orchestrating the inflammatory reaction in BP. These data may favour the employment of broad-spectrum or combined immunosuppressants, potentially together with an anticoagulant treatment, over cell- or molecule-specific targeted therapy in patients with this disorder.

Evidence for a contributory role of a xenogeneic immune response in experimental epidermolysis bullosa acquisita.

Autoimmune diseases affect a large fraction of the population in Western countries. To elucidate the underlying causes, autoantibody transfer-induced mouse models have been established that greatly contributed to the understanding of the pathophysiology of these diseases. However, the role of a potentially co-occurring murine xenogeneic immune response to commonly utilized rabbit anti-mouse IgG remains poorly understood. Using the established rabbit anti-mouse type VII collagen (COL7) IgG-induced mouse model of the mucocutaneous blistering disorder epidermolysis bullosa acquisita (EBA), we found in this study a profound T- and B-cell response along with an altered cytokine expression profile in draining lymph nodes of mice injected with the xenogeneic IgG. This was associated with the formation of circulating and skin-bound mouse anti-rabbit IgG in wild-type but not CD154-deficient or B-cell-deficient JHT mice challenged with pathogenic rabbit IgG. Development of EBA skin lesions was attenuated in the two mouse strains lacking a B-cell response at later observation time points, but was not affected in mice treated with the T-cell trafficking blocker FTY720. Collectively, our results implicate a host's xenoreactive immune response to rabbit anti-mouse COL7 IgG, a confounding effect that may contribute to immune complex-driven inflammation and tissue damage in this antibody transfer-induced EBA mouse model, especially at later time points. In this regard, it may be recommended to finish the evaluation of results obtained by experiments employing antibody-transferred mouse models within the first 2 weeks after the pathogenic antibody injection.

Periodontitis in oral pemphigus and pemphigoid: A systematic review of published studies.

Periodontitis and autoimmune bullous diseases, including pemphigus vulgaris and mucous membrane pemphigoid, are immunoinflammatory disorders leading to microbial plaque- and autoantibody-elicited tissue injury of the oral cavity, respectively. Evidence indicates that these autoimmune conditions may represent a risk factor for periodontitis, but no systematic evaluation exists to corroborate this assumption. A systematic literature review of periodontal status in pemphigus and pemphigoid was conducted. Electronic searches using PubMed from inception to July 2016 identified 10 studies meeting predetermined inclusion and exclusion criteria. Most reported some correlation between poor periodontal health and both oral pemphigus vulgaris and mucous membrane pemphigoid. Some demonstrated beneficial effects of oral hygiene procedures on periodontal parameters and clinical disease severity of the established blistering diseases. Inconsistent results were found between studies and within analyzed patient cohorts, likely because of methodological shortcomings. This review preliminarily suggests that patients with oral pemphigus vulgaris and mucous membrane pemphigoid appear somewhat more susceptible to periodontitis, which in turn may potentially trigger the bullous disorders. These patients should be encouraged by dermatologists to pursue collaborative professional periodontal follow-up with dentists. The true relationship and mutual interaction between both diseases needs to be more comprehensively addressed in well-designed prospective studies.

Broad requirement for terminal sialic acid residues and FcγRIIB for the preventive and therapeutic activity of intravenous immunoglobulins in vivo.

Intravenous immunoglobulin (IVIg) therapy is widely used to treat a variety of autoimmune diseases including immunothrombocytopenia, chronic inflammatory demyelinating polyneuropathy, and more recently autoimmune skin blistering diseases. Despite this well-documented clinical success, the precise molecular and cellular mechanisms underlying this immunomodulatory activity are discussed controversially. In particular, the clinically relevant therapeutic pathway of IVIg-mediated immune modulation has not been studied in detail. In the present study, we use four independent in vivo model systems of auto-Ab-mediated autoimmune disease to identify a common pathway explaining IVIg activity under therapeutic conditions in vivo. We show that irrespective of the in vivo model system, IVIg activity is strictly dependent on the presence of terminal sialic acid residues and the inhibitory FcγRIIB under preventive as well as therapeutic treatment conditions. In contrast, specific ICAM3 grabbing nonintegrin related 1, previously demonstrated to be essential under preventative treatment conditions, showed a disease-specific impact on IVIg-mediated resolution of established autoimmune disease.

Heat shock protein 90: a pathophysiological factor and novel treatment target in autoimmune bullous skin diseases.

The chaperone heat shock protein 90 (Hsp90), a cell stress-inducible molecule that regulates activity of many client proteins responsible for cellular growth, differentiation and apoptosis, has been proposed as an important therapeutic target in patients with malignancies. More recently, its active participation in (auto)immune processes has been recognized as evidenced by amelioration of inflammatory disease pathways through pharmacological inhibition of Hsp90 in rodent models of autoimmune encephalomyelitis, rheumatoid arthritis and systemic lupus erythematosus. Based on own current research results, this viewpoint essay provides important insights that Hsp90 is also involved as a notable pathophysiological factor in autoimmune blistering dermatoses including epidermolysis bullosa acquisita, bullous pemphigoid and possibly dermatitis herpetiformis. The observed in vitro, ex vivo and in vivo efficacy of anti-Hsp90 treatment in experimental models of autoimmune bullous diseases and its underlying multimodal anti-inflammatory mechanisms of interference with key contributors to autoimmune-mediated blister formation supports the introduction of selective non-toxic Hsp90 inhibitors into the clinical setting for the treatment of patients with these disorders.