Intravenous immunoglobulin selectively decreases circulating autoantibodies in pemphigus

T Regulatory Cell-Associated Tolerance Induction by High-Dose Immunoglobulins in an HLA-Transgenic Mouse Model of Pemphigus

Pemphigus vulgaris (PV) is a potentially lethal autoimmune bullous skin disorder caused by IgG autoantibodies against desmoglein 3 (Dsg3) and Dsg1. During the last three decades, high-dose intravenous immunoglobulins (IVIgs) have been applied as an effective and relatively safe treatment regime in severe, therapy-refractory PV. This prompted us to study T- and B- cell polarization by IVIg in a human-Dsg3-dependent mouse model for PV. Using humanized mice transgenic for HLA-DRB1*04:02, which is a highly prevalent haplotype in PV, we employed IVIg in two different experimental approaches: in prevention and quasi-therapeutic settings. Our data show that intraperitoneally applied IVIg was systemically distributed for up to 42 days or longer. IVIg-treated Dsg3-immunized mice exhibited, in contrast to Dsg3-immunized mice without IVIg, significantly less Dsg3-specific IgG, and showed induction of T regulatory cells in lymphatic tissue. Ex vivo splenocyte analysis upon Dsg3-specific stimulation revealed an initial, temporarily reduced antigen-induced cell proliferation, as well as IFN-γ secretion that became less apparent over the course of time. Marginal-zone B cells were initially reduced in the preventive approach but re-expanded over time. In contrast, in the quasi-therapeutic approach, a robust down-regulation in both spleen and lymph nodes was observed. We found a significant down-regulation of the immature transitional 1 (T1) B cells in IVIg-treated mice in the quasi-therapeutic approach, while T2 and T3, representing a healthy stage of B-cell development, appeared to be up-regulated by IVIg. In summary, in two experimental settings employing an active PV mouse model, we demonstrate distinct alterations of T- and B-cell populations upon IVIg treatment, compatible with a tolerance-associated polarization in lymphatic tissue. Our data suggest that the clinical efficacy of IVIg is at least modulated by distinct alterations of T- and B-cell populations compatible with a tolerance-associated polarization in lymphatic tissue.

A systematic review on efficacy, safety and treatment durability of intravenous immunoglobulin in autoimmune bullous dermatoses: Special focus on indication and combination therapy

Autoimmune bullous diseases (AIBDs) are a group of rare blistering dermatoses of the mucous membrane and/or skin. The efficacy, safety and treatment durability of intravenous immunoglobulin (IVIg) as an alternative treatment should be explored to systematically review the available literature regarding treatment outcomes with IVIg in AIBD patients. The predefined search strategy was incorporated into the following database, MEDLINE/PubMed, Embase, Scopus and Web of Science on 18 July 2022. Sixty studies were enrolled using Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. The use of IVIg alone or combined with rituximab was reported in 500 patients with pemphigus, 82 patients with bullous pemphigoid, 146 patients with mucous membranes pemphigoid and 19 patients with epidermolysis bullosa acquisita. Disease remission with IVIg therapy and RTX + IVIg combination therapy were recorded as 82.8% and 86.7% in pemphigus, 88.0% and 100% in bullous pemphigoid and 91.3% and 75.0% in mucous membrane pemphigoid, respectively. In epidermolysis bullosa acquisita, treatment with IVIg led to 78.6% disease remission; no data were available regarding the treatment with RTX + IVIg in this group of patients. Among all the included patients, 37.5% experienced at least one IVIg-related side effect; the most common ones were headaches, fever/chills and nausea/vomiting. The use of IVIg with or without rituximab had a favourable clinical response in patients with AIBDs. IVIg has no major influence on the normal immune system, which makes its utilization for patients with AIBDs reasonable.

Rationale for including intravenous immunoglobulin in the multidrug protocol of curative treatment of pemphigus vulgaris and development of an assay predicting disease relapse

Analysis of reported outcomes of treatment of pemphigus vulgaris (PV) patients demonstrated that the multidrug approach offers a lower relapse rate compared to the FDA-approved prednisone/rituximab regimen. The multidrug protocol protects keratinocytes from autoantibody attack by systemic corticosteroids and mitochondrion-protecting drugs, selectively eliminates pathogenic autoantibodies by intravenous immunoglobulin (IVIg) and inhibits autoantibody production by cytotoxic immunosuppressors. Therefore, IVIg should be always added to the prednisone/rituximab regimen that does not eliminate circulating autoantibodies. To decrease risk for relapse to a minimum, PV should be maintained in full clinical remission until the critical mass of autoreactive plasma cells dies off. The two major factors that determine patient's risk for a relapse are the composition of the pool of pathogenic autoantibodies and the innate abilities of keratinocytes to sustain an autoantibody attack. As it is currently impossible to evaluate the risk for a relapse, development of a biomarker assay that could do so would be helpful in a long-term management of PV patients. We compared the magnitude of cytochrome c (CytC) release in keratinocytes by serum from PV patients in acute disease stage vs. remission and identified very strong positive correlation with disease severity. PV patients whose serum contained autoantibodies requiring higher amounts of normal IgG to neutralize their ability to release CytC were found to be at a higher risk for disease relapse. However, lack of very strong statistical correlation suggested that CytC is not an ideal biomarker to predict disease relapse, which should prompt a search for alternative candidates.

Targeted Therapies for Autoimmune Bullous Diseases: Current Status

Autoimmune bullous skin disorders are rare but meaningful chronic inflammatory diseases, many of which had a poor or devastating prognosis prior to the advent of immunosuppressive drugs such as systemic corticosteroids, which down-regulate the immune pathogenesis in these disorders. Glucocorticoids and adjuvant immunosuppressive drugs have been of major benefit for the fast control of most of these disorders, but their long-term use is limited by major side effects such as blood cytopenia, osteoporosis, diabetes mellitus, hypertension, and gastrointestinal ulcers. In recent years, major efforts were made to identify key elements in the pathogenesis of autoimmune bullous disorders, leading to the identification of their autoantigens, which are mainly located in desmosomes (pemphigus) and the basement membrane zone (pemphigoids). In the majority of cases, immunoglobulin G, and to a lesser extent, immunoglobulin A autoantibodies directed against distinct cutaneous adhesion molecules are directly responsible for the loss of cell-cell and cell-basement membrane adhesion, which is clinically related to the formation of blisters and/or erosions of the skin and mucous membranes. We describe and discuss novel therapeutic strategies that directly interfere with the production and regulation of pathogenic autoantibodies (rituximab), their catabolism (intravenous immunoglobulins), and their presence in the circulation and extravascular tissues such as the skin (immunoadsorption), leading to a significant amelioration of disease. Moreover, we show that these novel therapies have pleiotropic effects on various proinflammatory cells and cytokines. Recent studies in bullous pemphigoid suggest that targeting of immunoglobulin E autoantibodies (omalizumab) may be also beneficial. In summary, the introduction of targeted therapies in pemphigus and pemphigoid holds major promise because of the high efficacy and fewer side effects compared with conventional global immunosuppressive therapy.

Unexpected worsening of pemphigus vulgaris after rituximab: A report of three cases

During the recent decade, several studies have confirmed the high efficacy of targeting the CD20 molecules using rituximab (RTX). Recently, RTX has been suggested as the first-line treatment of pemphigus vulgaris (PV). In this study, the records of all the PV patients, who had received RTX in Autoimmune Bullous Diseases Research Center, Tehran University of Medical Sciences between the 2009 and 2017, have been reviewed for any sign of disease worsening within three months after treatment. We have observed three PV patients from 612 RTX-exposed patients, who had experienced worsening of disease more than one time after discrete RTX cycles after the first infusion of RTX. All patients were successfully managed with different strategies (e.g., increase in steroid dosag intravenous immunoglobulin [IVIg], and plasmapheresis). In conclusion, despite the high efficacy of RTX therapy in PV patients, the exceptional risk of post-RTX disease worsening exists. Further studies are encouraged to develop (bio)markers to predict possible unexpected worsening of PV patients exposed to RTX.

Mechanisms of Disease: Pemphigus and Bullous Pemphigoid

Pemphigus and bullous pemphigoid are autoantibody-mediated blistering skin diseases. In pemphigus, keratinocytes in epidermis and mucous membranes lose cell-cell adhesion, and in pemphigoid, the basal keratinocytes lose adhesion to the basement membrane. Pemphigus lesions are mediated directly by the autoantibodies, whereas the autoantibodies in pemphigoid fix complement and mediate inflammation. In both diseases, the autoantigens have been cloned and characterized; pemphigus antigens are desmogleins (cell adhesion molecules in desmosomes), and pemphigoid antigens are found in hemidesmosomes (which mediate adhesion to the basement membrane). This knowledge has enabled diagnostic testing for these diseases by enzyme-linked immunosorbent assays and dissection of various pathophysiological mechanisms, including direct inhibition of cell adhesion, antibody-induced internalization of antigen, and cell signaling. Understanding these mechanisms of disease has led to rational targeted therapeutic strategies.

Intravenous immunoglobulin in the treatment of autoimmune bullous dermatoses: an update

High-dose intravenous immunoglobulin (IVIg) is being increasingly utilized as an off-label therapy for a variety of autoimmune and inflammatory conditions across various specialties. Numerous reports have shown that it is an effective treatment for autoimmune skin blistering disorders. Unlike most therapies for blistering disorders, IVIg is not immunosuppressive and has a favorable side effect profile. This has allowed its use to expand dramatically over the last decade. However, due to the rarity and severity of autoimmune skin blistering diseases, well-designed prospective trials are generally lacking. This work highlights major research developments and the best evidence to date regarding the treatment of autoimmune pemphigus, bullous pemphigoid, mucous membrane pemphigoid, epidermolysis bullosa acquisita, pemphigoid gestationis, and linear IgA dermatosis with IVIg, providing an update on its efficacy, proposed mechanisms of action, side effect profile, and indications for use.

Interventions for pemphigus vulgaris and pemphigus foliaceus

BACKGROUND

A range of interventions have been described for treatment of pemphigus, however the optimal therapeutic strategy has not been established.

OBJECTIVES

To assess the efficacy and safety of all interventions used in the management of pemphigus vulgaris and pemphigus foliaceus.

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (October 2008), The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 4, 2008), MEDLINE (2003 to October 2008), EMBASE (2005 to October 2008), LILACS (1981 to October 2008), Ongoing Trials Registers, reference lists of articles, conference proceedings from international pemphigus meetings and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials of any intervention in pemphigus vulgaris or pemphigus foliaceus.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed quality and extracted data from studies. All investigators were contacted for further information. Adverse events were identified from included studies.

MAIN RESULTS

Eleven studies with a total of 404 participants (337 pemphigus vulgaris, 27 pemphigus foliaceus and 40 not specified ) were identified. The quality of included studies was not high, the majority of studies did not report allocation concealment, and power was limited by very small sample sizes. Interventions assessed included prednisolone dose regimen, pulsed dexamethasone, azathioprine, cyclophosphamide, cyclosporine, dapsone, mycophenolate, plasma exchange, topical epidermal growth factor and traditional Chinese medicine. Ten studies included participants with newly diagnosed or newly active recurrent disease, and one trial included participants in maintenance phase.There was sufficient data for 4 meta-analyses, each pooling results of two studies only. For the majority of interventions, results were inconclusive. We found some interventions to be superior for certain outcomes, although we were unable to conclude which treatments are superior overall. Mycophenolate was more effective in achieving disease control than azathioprine (1 study; n=40; RR 0.72; 95% CI 0.52 to 0.99, NNT 3.7). There was evidence of a steroid-sparing benefit of azathioprine (1 study; n=57; MWD -3919 mg prednisolone; 95% CI -6712 to -1126) and cyclophosphamide (1 study; n=54; MWD -3355 mg prednisolone; 95% CI -6144 to -566) compared to glucocorticoids alone. Topical epidermal growth factor decreased time to control (1 study; n=20; HR 2.35; 95% CI 1.62 to 3.41).

AUTHORS' CONCLUSIONS

There is inadequate information available at present to ascertain the optimal therapy for pemphigus vulgaris or pemphigus foliaceus. Further research is required, especially to assess the optimal glucocorticoid dose, the role of adjuvant immunosuppressive medications, and long-term adverse events to improve harm:benefit analyses.

Advances in pemphigus and its endemic pemphigus foliaceus (Fogo Selvagem) phenotype: a paradigm of human autoimmunity

Pemphigus encompasses a group of organ specific, antibody mediated autoimmune diseases of the skin characterized by keratinocyte detachment that leads to the development of blisters and erosions, which can become life-threatening. The pathogenic autoantibodies recognize desmogleins, which are members of the desmosomal cadherin family of cell adhesion molecules. Desmoglein 3 is targeted in pemphigus vulgaris while desmoglein 1 is targeted in pemphigus foliaceus and its endemic form, Fogo Selvagem. This review will briefly define the salient features of pemphigus and the proposed steps in pathogenesis. We will then summarize the most recent advances in three important areas of investigation: (i) epidemiologic, genetic, and immunologic features of Fogo Selvagem, (ii) molecular mechanisms of injury to the epidermis, and (iii) novel therapeutic strategies targeting specific steps in disease pathogenesis. The advances in each of these three seemingly separate areas contribute to the overall understanding of the pemphigus disease model. These recent advancements also underscore the dynamic interplay between the treatment of patients in a clinical setting and basic science research and have led to an integrative understanding of disease pathogenesis and treatment, allowing pemphigus to serve as a paradigm of human autoimmunity.