Detection and characterization of anti-envoplakin linker autoantibodies in paraneoplastic pemphigus using specific bead-based assay

Paraneoplastic Pemphigus and Autoimmune Blistering Diseases Associated with Neoplasm: Characteristics, Diagnosis, Associated Neoplasms, Proposed Pathogenesis, Treatment

Autoimmune paraneoplastic and neoplasm-associated skin syndromes are characterized by autoimmune-mediated cutaneous lesions in the presence of a neoplasm. The identification of these syndromes provides information about the underlying tumor, systemic symptoms, and debilitating complications. The recognition of these syndromes is particularly helpful in cases of skin lesions presenting as the first sign of the malignancy, and the underlying malignancy can be treated in a timely manner. Autoimmune paraneoplastic and neoplasm-associated bullous skin syndromes are characterized by blister formation due to an autoimmune response to components of the epidermis or basement membrane in the context of a neoplasm. The clinical manifestations, histopathology and immunopathology findings, target antigens, associated neoplasm, current diagnostic criteria, current understanding of pathogenesis, and treatment options for a selection of four diseases are reviewed. Paraneoplastic pemphigus manifests with clinically distinct painful mucosal erosions and polymorphic cutaneous lesions, and is often associated with lymphoproliferative neoplasm. In contrast, bullous pemphigoid associated with neoplasm presents with large tense subepidermal bullae of the skin, and mild mucosal involvement, but without unique clinical features. Mucous membrane pemphigoid associated with neoplasm is a disorder of chronic subepithelial blisters that evolve into erosions and ulcerations that heal with scarring, and involves stratified squamous mucosal surfaces. Linear IgA dermatosis associated with neoplasm is characterized by annularly grouped pruritic papules, vesicles, and bullae along the extensor surfaces of elbows, knees, and buttocks. Physicians should be aware that these autoimmune paraneoplastic and neoplasm-associated syndromes can manifest distinct or similar clinical features as compared with the non-neoplastic counterparts.

Comparative study of five serological assays for the diagnosis of paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous blistering disease driven by autoantibodies against plakins expressed in mucosal epithelium. Diagnosis can be difficult as both clinical and biopsy features overlap with other blistering disorders, thus serology is important. Indirect immunofluorescence (IIF) on rat bladder substrate is the most widely used assay, but plakin-specific autoantibody assays have recently become available.The aim of this study was to compare the performance of five PNP assays in patients with mucosal blistering disease: IIF with rat bladder, monkey bladder and rat cardiac substrates, an envoplakin enzyme-linked immunosorbent assay (ELISA), and an envoplakin-transfected HEK cell based assay (CBA).Fifty-one patient serum samples, comprising three PNP patients and 48 disease controls, were collected along with 10 healthy control samples, and analysed using the five assays.IIF on rat and monkey bladder substrates both showed high specificity (97% and 95%, respectively), and correctly identified all three PNP sera. The envoplakin ELISA was equally specific (98%) but identified only one PNP patient. The CBA was difficult to interpret, and both this assay and IIF on rat cardiac substrate lacked specificity (82% and 83%, respectively).In this study IIF using either rat or monkey bladder substrates performed strongly, whilst the envoplakin ELISA seemed to lack sensitivity, and the CBA and IIF on rat cardiac substrate were inferior. Our findings suggest that traditional IIF-based assays remain the preferred approach in the serological diagnosis of PNP.

Oral mucosal manifestations of autoimmune skin diseases

A group of autoimmune diseases is characterised by autoantibodies against epithelial adhesion structures and/or tissue-tropic lymphocytes driving inflammatory processes resulting in specific pathology at the mucosal surfaces and the skin. The most frequent site of mucosal involvement in autoimmune diseases is the oral cavity. Broadly, these diseases include conditions affecting the cell-cell adhesion causing intra-epithelial blistering and those where autoantibodies or infiltration lymphocytes cause a loss of cell-matrix adhesion or interface inflammation. Clinically, patients present with blistering, erosions and ulcers that may affect the skin as well as further mucosal surfaces of the eyes, nose and genitalia. While the autoimmune disease may be suspected based on clinical manifestations, demonstration of tissue-bound and circulating autoantibodies, or lymphocytic infiltrates, by various methods including histological examination, direct and indirect immunofluorescence microscopy, immunoblotting and quantitative immunoassay is a prerequisite for definitive diagnosis. Given the frequency of oral involvement and the fact that oral mucosa is the initially affected site in many cases, the informed practitioner should be well acquainted with diagnostic and therapeutic aspects of autoimmune dermatosis with oral involvement. This paper reviews the pathogenesis and clinical presentation of these conditions in the oral cavity with a specific emphasis on their differential diagnosis and current management approaches.

Molecular diagnosis in autoimmune skin blistering conditions

Blister formation in skin and mucous membranes results from a loss of cell-cell or cell-matrix adhesion and is a common outcome of pathological events in a variety of conditions, including autoimmune and genetic diseases, viral and bacterial infections, or injury by physical and chemical factors. Autoantibodies against structural components maintaining cell-cell and cell-matrix adhesion induce tissue damage in autoimmune blistering diseases. Detection of these autoantibodies either tissue-bound or circulating in serum is essential to diagnose the autoimmune nature of disease. Various immunofluorescence methods as well as molecular immunoassays, including enzyme-linked immunosorbent assay and immunoblotting, belong to the modern diagnostic algorithms for these disorders. There is still a considerable need to increase awareness of the rare autoimmune blistering diseases, which often show a severe, chronic-relapsing course, among physicians and the public. This review article describes the immunopathological features of autoimmune bullous diseases and the molecular immunoassays currently available for their diagnosis and monitoring.

Detection of autoantibodies to periplakin and envoplakin in paraneoplastic pemphigus but not idiopathic pulmonary fibrosis using full-length recombinant proteins

BACKGROUND

Paraneoplastic pemphigus (PNP) serum preferentially reacts with periplakin and envoplakin, which are plakin family proteins localized to desmosomes and intermediate filaments. Recently, anti-periplakin antibodies were also detected in patients with idiopathic pulmonary fibrosis (IPF). Although previous epitope-mapping studies showed multiple epitopes in each protein, enzyme-linked immunosorbent assays have used several truncated, but not full-length, recombinant proteins.

METHODS

This study aimed to produce full-length biotinylated recombinant proteins of periplakin and envoplakin for detection of autoantibodies by immunoprecipitation and ELISA. Serum from a PNP patient who had been confirmed as carrying anti-periplakin and anti-envoplakin antibodies in our previous study was used as a positive control. Sera from 15 patients with IPF were analyzed for both antibodies by immunoprecipitation and by ELISA.

RESULTS

The PNP serum reacted strongly with the full-length recombinant proteins in immunoprecipitation and ELISA. Longitudinal serum samples from the PNP patient showed a clear decline of autoantibodies to both periplakin and envoplakin. None of the IPF sera showed both autoantibodies.

CONCLUSIONS

We found that the detection of anti-periplakin and anti-envoplakin antibodies using full-length recombinant proteins is useful immunoprecipitation and ELISA.

Diagnostics of autoimmune bullous diseases in German dermatology departments

BACKGROUND

No consistent data are available on the currently employed diagnostic tools for autoimmune bullous diseases in Germany. The aim of this survey was to describe currently performed diagnostic methods for bullous autoimmune diseases in German dermatology departments.

METHODS

A standardized questionnaire evaluated the available diagnostic methods i. e. direct immunofluorescence microscopy (IFM), indirect IFM, commercial ELISA systems, and non-commercial serological tests as well as the number of samples per year in all 34 university and 39 non-university dermatology departments.

RESULTS

The overall return rate was 89 %, 100 % and 79 % for the university and non-university departments, respectively. Direct IFM was the most frequently used method and was applied in 98 % of the responding departments. In 74 % of the responding departments, indirect IFM was used mainly on monkey esophagus and human salt-split skin. Commercial ELISA systems were employed in 58 % of the clinics; all of them used anti-desmoglein ELISA, while anti-BP180 and anti-BP230 ELISA were established in 49 % and 48 % of departments, respectively. Non-commercial analytic methods were only performed in 22 % of the departments.

CONCLUSIONS

The high return rate of this survey allows a relatively precise description of the current diagnostic methods used in German dermatology departments. Standard diagnostic tests are available nationwide and in bullous pemphigoid and pemphigus, the antigen-specific detection of autoantibodies is routinely performed in half of the departments. Rare disorders may be diagnosed by cooperation with some specialized centers.

[Pemphigus]

Pemphigus is a rare autoimmune blistering disorder involving the skin and mucosae. Three types of pemphigus have been described, including pemphigus vulgaris, pemphigus foliaceus and paraneoplastic pemphigus. Diagnosis of the type of pemphigus is made by the combination of clinical features, histological and direct immunofluorescence findings, and serum analysis by indirect immunofluorescence, immunoblot analysis and enzyme-linked-immunosorbent-assay (Elisa). Most patients are treated with oral corticosteroids, sometimes associated with immunosuppressants. Patients with treatment failure or with contraindications to systemic corticosteroids and/or immunosuppressants may be treated with intravenous immunoglobulins or rituximab, an anti-CD20 monoclonal antibody.

Clinical and immunopathological spectrum of paraneoplastic pemphigus

BACKGROUND

Paraneoplastic pemphigus (PNP) is a rare life-threatening autoimmune bullous disorder. The clinical picture is often polymorphous and blisters may be absent. Autoantibodies are directed against several target antigens, including plakins and desmogleins. PNP has a high mortality rate that does not directly depend on the malignancy of the neoplasm. No generally accepted diagnostic criteria for PNP have been defined.

PATIENTS AND METHODS

On the basis of four selected PNP patients and the relevant literature, the spectrum of clinical and immunopathological findings as well as pathogenesis and treatment options of PNP are presented.

RESULTS

In addition to a neoplasm, severe stomatitis and the presence of autoantibodies against periplakin and envoplakin are characteristic for PNP. Based on the presented data, diagnostic criteria are proposed.

CONCLUSIONS

Knowledge of the polymorphous clinical picture and the complex autoantibody response is essential for an early diagnosis of PNP which has implications for both prognosis and rapid initiation of treatment.