Human autoantibodies against desmoplakins in paraneoplastic pemphigus

Molecular abnormalities of the desmosomal protein desmoplakin in human disease

Desmoplakin is the principal plaque protein of desmosomes, specialized adhesion junctions found in various tissues including skin, heart and meninges. It is an entirely intracellular protein and in keratinocytes desmoplakin binds to other structural components of desmosomes such as cadherins and armadillo proteins, as well as to keratin filaments. Clues to the biological significance of desmoplakin have recently emerged from a number of naturally occurring human desmoplakin gene mutations. Both autosomal dominant and autosomal recessive disorders have been reported. The spectrum of clinical features includes varying degrees of keratoderma, blisters, nail dystrophy, woolly hair and, in some cases, cardiomyopathy. This review provides an update on genotype-phenotype correlation for human desmoplakin mutations as well as an overview of desmoplakin abnormalities in other conditions, including autoimmune blistering diseases, epithelial malignancies and blood vessel morphogenesis.

Pemphigus

Pemphigus is an umbrella term for more than 10 different epidermal disease types and subtypes currently classified under this name. Characteristic for pemphigus are the presence of autoantibodies against epidermal cell adhesion structures (desmosomes), leading to a breakdown of cutaneous and mucosal barriers. The two most important disease types for dentists are pemphigus vulgaris and paraneoplastic pemphigus because they almost invariably present with oral manifestations. This article highlights current knowledge on the pathophysiology, the clinical signs, and the practical clinical diagnostic approach to these two serious disorders and treatment.

Mucosal dominant pemphigus vulgaris with anti-desmoplakin autoantibodies

BACKGROUND

Anti-desmoplakin (DP) antibodies are present in paraneoplastic pemphigus (PNP) as a component of a complex humoral autoimmune reaction characterized by antibodies against proteins of the plakin family, desmogleins, and an unidentified 170 kd protein. Anti-DP antibodies have also been rarely identified in other blistering diseases. The significance of anti-DP antibodies in the pathogenesis of bullous diseases is unclear.

OBSERVATION

We studied 3 patients with severe and chronic mucosal dominant pemphigus vulgaris (PV). In addition to anti-desmoglein 3 antibodies, these patients had anti-DP autoantibodies, demonstrable by immunofluorescence (IF), immunoprecipitation (IP), and indirect immunoelectromicroscopy (IIEM). This finding suggested these patients may have had PNP and not PV. However, antibodies against periplakin, envoplakin, bullous pemphigoid antigen 1 (BPAG 1), plectin, and 170 kd PNP antigen could not be detected using IP and immunoblotting. Extensive and repeated investigations for an underlying neoplasm throughout the follow-up period were consistently negative for all patients.

CONCLUSION

This study demonstrates that anti-DP antibodies without the presence of any other anti-plakin antibodies are not specific for PNP, and are present in some cases of PV. Cellular disadhesion induced by anti-desmoglein antibodies can trigger an epitope-spreading phenomenon with a secondary formation of autoantibodies against desmoplakins, intracellular desmosomal antigens. The role of anti-DP antibodies in the pathogenesis of these PV patients is still unclear. The presence of anti-DP antibodies will produce a false positive serologic interpretation for the diagnosis of PNP especially if one uses only indirect IF on murine bladder, the most commonly employed screening test to identify PNP. More specific immunologic tests are required in this subset of patients with PV.

Exacerbation of paraneoplastic pemphigus by cyclophosphamide treatment: detection of novel autoantigens and bronchial autoantibodies

A 48-year-old woman with a follicular, grade III, B-cell non-Hodgkin lymphoma developed clinical, immunopathological and histological features of paraneoplastic pemphigus. The skin symptoms flared after repeated cyclophosphamide infusions, and were preceded and accompanied by a progressive dyspnoea. Although the skin and oral mucosal disease went into remission with high-dose steroid and intravenous immunoglobulin therapy, the severe alveolitis led to death. Immunoblotting of human epidermal extracts showed that the patient's serum IgG reacted with the 210-kDa envoplakin, 190-kDa periplakin, as well as the recombinant protein of BP180 NC16a domain. IgG and IgA enzyme-linked immunosorbent assays for desmoglein 3 were positive, too. Indirect immunofluorescence studies on COS-7 cells transiently transfected with desmocollin 1-3 cDNAs showed that the patient's serum contained IgG and IgA antibodies to desmocollin 3 as well as IgG antibodies to desmocollin 2. Serum IgG and IgA strongly stained rat bronchial epithelium, corresponding to autoantibodies possibly involved in the pathomechanism of the severe lung disease. In this case, which was characterized by a mixed IgA/IgG antibody panel displaying known and unique antigenicity, the serious episodes of paraneoplastic pemphigus flared after cyclophosphamide treatment.

Progressive Respiratory Failure in Paraneoplastic Pemphigus Associated with Chronic Lymphocytic Leukemia

A 70-year-old Caucasian man with chronic lymphocytic leukemia suffered from widespread, histologically proven cutaneous lichen planus responding to topical corticosteroids. 2 years later, he presented with painful erosive stomatitis and increasing dyspnea. Histology, direct and indirect immunofluorescence were diagnostic for paraneoplastic pemphigus. A full diagnostic workup could not disclose the cause of the progressive respiratory insufficiency. Despite aggressive treatment of the lymphocytic leukemia and the paraneoplastic pemphigus, the patient died 3 months after diagnosis. Paraneoplastic pemphigus may lead to pulmonary failure which is refractory to treatment and has a fatal outcome.

The intraepidermal blistering conditions

The intraepidermal vesiculobullous disorders constitute a wide variety of pathogenically unrelated disorders that share in common the formation of cleft or bullae formation within the epithelium. The etiologic, pathogenic, clinical and, in particular, the histopathologic attributes of the most important intraepidermal blistering conditions are described.

Blistering diseases in the elderly: diagnosis and treatment

This article discusses the major blistering diseases in the geriatric population. The diagnosis of both immune- and non-immune-mediated blistering disorders can be confirmed with the help of histologic and immunopathologic studies. Various serologic assays, which are more specific, also can be used to confirm the diagnosis of autoimmune blistering diseases. These techniques have facilitated the diagnosis and allowed the institution of early treatment. The treatment of blistering disorders has included both localized and systemic treatments. Localized treatment involves topical care including the following measures: the prevention of trauma; soaking of blisters in antiseptic (potassium permanganate or aluminum subacetate) solutions; topical and intralesional corticosteroids; and the prevention and early treatment of infections with local or systemic antibiotics. Conventional oral systemic therapies that have proved to be beneficial include systemic corticosteroids, anti-inflammatory agents, and immunosuppressive agents. Because the elderly are more prone to the side effects of these systemic agents, it is crucial that routine hematologic tests be done and monitored until the treatments have been discontinued. Recently, newer alternative treatment modalities have proved to be successful in patients who failed to respond or developed multiple side effects to the conventional oral systemic agents. In conclusion, as clinicians gain a greater understanding into the pathogenesis of these diseases, more specific molecular-targeted treatments will most likely become available.

Blistering disorders: diagnosis and treatment

Blistering diseases are a heterogeneous group of disorders that can affect either skin and mucous membrane, or both, varying in presentation, clinical course, pathohistology, immunopathology and treatment. Not infrequently the diagnosis is delayed. This can result in severe, and sometimes fatal consequences. Although these diseases are rare, it is very important to make an accurate diagnosis based on a combination of clinical profile and laboratory observations. A brief review is presented of the following bullous diseases: pemphigus, paraneoplastic pemphigus, bullous pemphigoid, cicatricial pemphigoid, epidermolysis bullosa acquisita, dermatitis herpetiformis, linear IgA bullous disease, porphyria cutanea tarda, and subcorneal pustular dermatitis. Their clinical, pathohistologic and immunopathologic features and recommendations for therapy are discussed.

Castleman's tumours and production of autoantibody in paraneoplastic pemphigus

BACKGROUND

Paraneoplastic pemphigus is an autoimmune mucocutaneous disease associated with Castleman's tumours, which when surgically removed often result in great improvement of mucocutaneous lesions. An IgG autoantibody against epidermal proteins is often used as a diagnostic marker for disease. Our aim was to ascertain the role of Castleman's tumours in production of the autoantibody and pathogenesis of paraneoplastic pemphigus.

METHODS

We enrolled seven patients with paraneoplastic pemphigus associated with Castleman's disease and assessed the effect of removal of tumours on mucocutaneous lesions in six individuals and on autoantibody titre with indirect immunofluorescence in four patients. We cultured tumour cells from one patient and assayed the secreted autoantibody. Finally, we characterised the gene sequence and expression of the variable region of the immunoglobulin heavy chain (IgV(H)) in tumour B cells from all patients by reverse transcription-PCR, DNA sequencing, and in-situ hybridisation.

FINDINGS

Cutaneous lesions disappeared within 6-11 weeks after resection of tumours. Mucosal lesions also improved in this period, but lasted for 5-10 months overall. Autoantibody titre decreased and became undetectable within 5-9 weeks in three of four patients assessed. We identified secreted autoantibody, similar to that identified in patients' serum, in cultured tumour cells. The tumour B-cells of the seven patients shared and expressed two rearrangement patterns of complementarity determining region 3 (CDR3) of IgV(H).

INTERPRETATION

Secreted autoantibody from Castleman's tumours, which reacts against epidermal proteins, could be an essential factor in the pathogenesis of paraneoplastic pemphigus. We noted clonal rearrangement, resulting in similar variable regions of IgV(H), in tumour B cells isolated from all seven patients. However, whether this pattern is associated with autoimmunity remains to be ascertained.

Comparative study of autoantigen profile between Colombian and Brazilian types of endemic pemphigus foliaceus by various biochemical and molecular biological techniques

BACKGROUND

Besides Brazilian endemic pemphigus foliaceus (EPF), we have described another focus of EPF in Colombia. Our previous study suggested that Colombian EPF seemed to react various plakin family proteins, such as envoplakin, periplakin and BP230.

OBJECTIVE

To further characterize the Colombian EPF and study the difference from Brazilian EPF, we examined the antigen profile of the two types of EPF.

METHODS AND RESULTS

Immunoblotting using normal human epidermal extracts revealed that 38% Colombian EPF sera and 25% Brazilian EPF sera showed IgG antibodies reactive with desmoglein (Dsg) 1, pemphigus foliaceus antigen. The sera of both types of EPF showed protein bands co-migrating with plakin family proteins, particularly periplakin. Immunoblotting analyses using recombinant proteins of various domains of envoplakin, periplakin and BP230 revealed that a considerable number of Colombian EPF sera reacted with recombinant proteins of periplakin, while only few Brazilian sera reacted with some of the recombinant proteins of any plakins. Enzyme-linked immunosorbent assay (ELISA) for Dsg1 and Dsg3 showed that Dsg1 was reacted by almost all sera of both types of EPF. However, unexpectedly, while none of Colombian EPF sera reacted with Dsg3, about half of Brazilian EPF sera reacted with Dsg3.

CONCLUSION

These results suggested that the Colombian EPF is basically similar to Brazilian EPF in terms that major antigen is Dsg1, but there were some different antigen profiles between the two types of EPF.

Recent advances in the study of the pathophysiology of pemphigus

Recent rapid advances in the basic research into pemphigus have provided many insights into its pathophysiology. In particular, a recently developed enzyme-linked immunosorbent assay (ELISA) for desmogleins 1 and 3 (Dsg1 and Dsg3), antigens for pemphigus foliaceus (PF) and pemphigus vulgaris (PV), respectively, has led to great progress in the diagnosis and classification of pemphigus, as well as in understanding its pathomechanisms. Studies with the anti-Dsg1 and anti-Dsg3 antibodies have indicated that there are two types of PV, the mucosal dominant type and the mucocutaneous type. The same ELISA has identified the antigens in pemphigus herpetiformis. The autoantigens detected by this ELISA correlate well with the clinical features in pemphigus patients in showing the shift between PV and PF. In addition, the Dsg compensation theory proposed by Stanley and Amagai can reasonably explain the different depths of skin lesions and the different occurrences of skin and oral mucosal lesions between PV and PF. Furthermore, a complicated profile of autoantigens in paraneoplastic pemphigus (PNP) has been indicated in various biochemical studies, and IgG anti-Dsg1 and anti-Dsg3 antibodies have been detected in serum from all the PNP patients by the above ELISA. On the other hand, serum from subcorneal pustular dermatosis type IgA pemphigus patients have been shown to react with Dsc1, another type of desmosomal cadherin, by a novel cDNA transfection method. In addition, IgA anti-Dsg1 and anti-Dsg3 antibodies have been detected in a few patients with IgA pemphigus by an ELISA for IgA antibodies. Various autoimmune bullous diseases, including several types of pemphigus, are the only diseases in which the pathogenic role of circulating autoantibodies has been confirmed using the newborn mouse animal model. Therefore, studies of the pathophysiology of pemphigus are extremely important as a paradigm for research into various types of autoimmune diseases in other fields.

Genetic evidence for a novel human desmosomal cadherin, desmoglein 4

Desmosomes are essential adhesion structures in most epithelia that link the intermediate filament network of one cell to its neighbor, thereby forming a strong bond. The molecular components of desmosomes belong to the cadherin superfamily, the plakin family, and the armadillo repeat protein family. The desmosomal cadherins are calcium-dependent transmembrane adhesion molecules and comprise the desmogleins and desmocollins. To date, three human desmoglein isoforms have been characterized, namely desmogleins 1, 2, and 3 that are expressed in a tissue- and differentiation-specific manner. Here we have identified and characterized, at the genetic level, a novel human desmoglein cDNA sharing homology with desmogleins 1, 2, 3 and we name this desmoglein 4. The human desmoglein 4 cDNA (3.6 kb) contains an open reading frame of 3120 bp that encodes a precursor protein of 1040 amino acids. The predicted mature protein comprises 991 amino acids with a molecular weight of 107822 Da at pI 4.38. Human desmoglein 4 shares 41% identity with human desmoglein 1, 37% with human desmoglein 2, and 50% with human desmoglein 3. Analysis of the exon/intron organization of the human desmoglein 4 gene (DSG4) demonstrates that it is composed of 16 exons spanning approximately 37 kb of 18q12 and is situated between DSG1 and DSG3. We have demonstrated using RT-PCR on multiple tissue cDNA samples that desmoglein 4 has very specific tissue expression in salivary gland, testis, prostate, and skin.

Paraneoplastic pemphigus in children and adolescents

BACKGROUND

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous disease associated with specific B-cell lymphoproliferative neoplasms. There has been an increasing number of individual reports in the childhood and adolescent population.

OBJECTIVES

To examine the clinical and immunopathological features of PNP occurring in children and adolescents.

PATIENTS AND METHODS

We analysed the clinical and immunopathological findings of 14 patients under the age of 18 years with a confirmed diagnosis of PNP. Sera from all patients were analysed by indirect immunofluorescence (IF) and immunoprecipitation for plakin autoantibodies, immunoblotting for detection of plectin autoantibodies, and enzyme-linked immunosorbent assay (ELISA) for the detection of desmoglein (Dsg) 1 and Dsg3 autoantibodies.

RESULTS

Severe oral mucositis was observed in all patients, and lichenoid cutaneous lesions in eight of 14 patients. The average age at presentation was 13 years. Striking findings included: pulmonary destruction leading to bronchiolitis obliterans in 10 patients, association with Castleman's disease in 12 patients, and a fatal outcome in 10 patients. The underlying neoplasm was occult in 10 patients. Histological findings include lichenoid and interface dermatitis with variable intraepithelial acantholysis. Deposition of IgG and C3 in the mouth and skin by direct IF was not found in some cases, but indirect IF detected IgG autoantibodies in all cases. Immunoprecipitation revealed IgG autoantibodies against desmoplakin I, envoplakin and periplakin in all cases, and against desmoplakin II and the 170-kDa antigen in 13 and 10 patients, respectively. Dsg3 and Dsg1 autoantibodies were present in 10 and three patients, respectively, and plectin autoantibodies in 13 patients.

CONCLUSIONS

PNP in children and adolescents is most often a presenting sign of occult Castleman's disease. It presents with severe oral mucositis and cutaneous lichenoid lesions. Serum autoantibodies against plakin proteins were the most constant diagnostic markers. Pulmonary injury appears to account for the very high mortality rates observed.

Paraneoplastic pemphigus sera react strongly with multiple epitopes on the various regions of envoplakin and periplakin, except for the c-terminal homologous domain of periplakin

Paraneoplastic pemphigus sera react with multiple plakin family proteins, among which only envoplakin and periplakin are constantly detected by immunoblotting using normal human epidermal extracts. Using bacterial expression vectors containing polymerase chain reaction-amplified cDNA, we have prepared variously truncated recombinant glutathione-S-transferase-fusion proteins of envoplakin and periplakin, which presented N-terminal, central and C-terminal domains of each protein, as well as the so-called C-terminal homologous domain of envoplakin and the junctional regions of these domains. By immunoblotting using these 11 recombinant proteins, we demonstrated that most of the 26 paraneoplastic pemphigus sera reacted very strongly with multiple recombinant proteins of envoplakin and periplakin, except for the C-terminal homologous domain of periplakin. We also examined the reactivity with these recombinant proteins of other blistering diseases, including pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid, and found that a few nonparaneoplastic pemphigus sera showed a weak reactivity with some of the recombinant proteins. Interestingly, some sera showed relatively strong reactivity with the C-terminal homologous domain of periplakin to which paraneoplastic pemphigus sera reacted less frequently. These results indicate that, although nonparaneoplastic pemphigus sera occasionally show a weak reactivity with envoplakin and periplakin, the pathogenicity and the mechanism of antibody production in these cases may be different from those in paraneoplastic pemphigus.

Paraneoplastic pemphigus as the initial presentation of chronic lymphocytic leukemia

The case history of a 61-year-old male patient is described, who presented with severe stomatitis, conjunctivitis and leukocytosis. The diagnosis chronic lymphocytic leukemia (CLL) stage A (0) was made, for which no treatment was necessary. Progression of stomatitis and conjunctivitis and erythosquamous skin lesions with bullae and vesiculae formation developed. Under the diagnosis of bullous pemphigoid the patient was treated with corticosteroids. The histologic and immunofluorescence examination of a skin biopsy was compatible with this diagnosis, and antibodies to skin could not be detected in a first serum sample. Pseudomonas was cultured from all lesions, the corticosteroids were stopped and antibiotic treatment was started, without clear effect. Because of progression of skin lesions and debilitation, the patient finally declined all treatment and died five weeks after admission. Post-mortem examination showed enlarged lymphnodes in the cervical, aortal en iliacal areas, with histology confirming the diagnosis of CLL. Indirect immunofluorescence with the second serum sample showed auto-antibodies in high titer directed against the intercellular epithelial substance. Immunoblot studies showed binding with the classic target antigens in paraneoplastic pemphigus. Re-examination of the histologic skin specimen and the result of direct immunofluorescence were in retrospect compatible with the diagnosis of paraneoplastic pemphigus.

Sensitivity and specificity of clinical, histologic, and immunologic features in the diagnosis of paraneoplastic pemphigus

BACKGROUND

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease characterized by the production of autoantibodies mainly directed against proteins of the plakin family. An overlapping distribution of autoantibody specificities has been recently reported between PNP, pemphigus vulgaris (PV), and pemphigus foliaceus (PF), which suggests a relationship between the different types of pemphigus.

OBJECTIVE

Our purpose was to evaluate the sensitivity and the specificity of clinical, histologic, and immunologic features in the diagnosis of PNP.

METHODS

The clinical, histologic, and immunologic features of 22 PNP patients were retrospectively reviewed and compared with those of 81 PV and PF patients without neoplasia and of 8 PV and 4 PF patients with various neoplasms.

RESULTS

One clinical and 2 biologic features had both high sensitivity (82%-86%) and high specificity (83%-100%) whatever the control group considered: (1) association with a lymphoproliferative disorder, (2) indirect immunofluorescence (IIF) labeling of rat bladder, and (3) recognition of the envoplakin and/or periplakin bands in immunoblotting. Two clinicopathologic and two biologic features had high specificity (87%-100%) but poor sensitivity (27%-59%): (1) clinical presentation associating erosive oral lesions with erythema multiforme-like, bullous pemphigoid-like, or lichen planus-like cutaneous lesions; (2) histologic picture of suprabasal acantholysis with keratinocyte necrosis, interface changes, or lichenoid infiltrate; (3) presence of both anti-epithelial cell surface and anti-basement membrane zone antibodies by IIF; and (4) recognition of the desmoplakin I and/or BPAG1 bands in immunoblotting. Interestingly, 45% of patients with PNP presented initially with isolated oral erosions that were undistinguishable from those seen in PV patients, and 27% had histologic findings of only suprabasal acantholysis, which was in accordance with the frequent detection of anti-desmoglein 3 antibodies in PNP sera.

CONCLUSION

The association with a lymphoproliferative disorder, the IIF labeling of rat bladder, and the immunoblotting recognition of envoplakin and/or periplakin are both sensitive and specific features in the diagnosis of PNP.

Pemphigus with pemphigoid-like presentation, associated with squamous cell carcinoma of the tongue

A 53-year-old woman presented with an inoperable squamous cell carcinoma of the tongue associated with tense large bullae consistent with bullous pemphigoid, preceded by a prodrome of urticarial plaques. The histological findings showed a regenerating subepidermal blister with eosinophils and no acantholysis. Direct immunofluorescence study, however, showed positive staining for IgG and C3 throughout the epidermis consistent with pemphigus. The blistering eruption had no mucosal involvement and responded to low dose corticosteroids. Our patient may represent another presentation of a 'paraneoplastic pemphigus spectrum'.

A paraneoplastic mixed bullous skin disease: breakdown in tolerance to multiple epidermal antigens

We report a new type of paraneoplastic mixed bullous skin disease in a patient with a B-cell lymphoma associated with monoclonal IgM kappa paraproteinaemia. The patient's clinical and histological features were reminiscent of bullous pemphigoid. Characterization of antiepidermal antibodies by immunoblotting and indirect immunoelectron microscopy demonstrated a novel pattern of reactivity: IgG antibodies were directed against desmoplakins I-II and BPAG2, and were associated with antidesmoglein 3 polyclonal IgM antibodies. Such an autoreactive pattern involving antidesmoplakins, anti-BPAG2 and antidesmoglein 3 antibodies has not been previously reported. It reflects the breakdown of tolerance to multiple epidermal antigens observed in some patients with malignancy.

Paraneoplastic pemphigus: a review of the literature

Paraneoplastic pemphigus is a relatively rare but highly significant acquired mucocutaneous disorder. The condition typically presents in patients with previously diagnosed lymphoreticular disease, primarily malignancies (non-Hodgkin's lymphoma; chronic lymphocytic leukemia). Multiple sites of involvement are common, with the skin affected by a polymorphous eruption that includes lichenoid plaques as well as bullae. The oral lesions occur in all cases and present as painful widespread shallow ulcers with hemorrhagic crusting of the lips. Conjunctival involvement is also seen and may result in scarring. Pulmonary lesions are an ominous sign. Histopathologically, intraepithelial and subepithelial clefting associated with interface dermatitis are seen. A variety of autoantibodies directed against desmoplakins and desmogleins can be identified with immunoprecipitation studies. Treatment with immunosuppressive agents may result in some resolution of the disease, but the prognosis for paraneoplastic pemphigus is considered to be poor.

Paraneoplastic pemphigus associated with Castleman's tumour

We present a case of paraneoplastic pemphigus associated with Castleman's disease. Our patient had stomatitis and vulvar erosions followed by a cutaneous polymorphous eruption. Investigations for neoplasia disclosed a Castleman's tumour suggesting the diagnosis of paraneoplastic pemphigus. The diagnosis was supported by immunoblotting using an extract of cow tongue although keratinocytes extracts did not identify relevant target antigens. One year after surgical excision of the tumour the patient remained unwell with persistent buccal erosions and lymphopenia. This case is unusual because of the length of its evolution before the discovery of the Castleman's tumour. It is only the second occasion that the association between paraneoplastic pemphigus and Castleman's tumour has been reported. Our case emphasizes the usefulness of immunoblotting on cow tongue in suspected cases of paraneoplastic pemphigus.

Paraneoplastic pemphigus associated with Castleman tumor, myasthenia gravis and bronchiolitis obliterans

BACKGROUND

Cases of paraneoplastic pemphigus (PNP) have been reported associated with various lymphoproliferative malignancies and benign Castleman tumors, with the most severe course and fatal outcome seen in patients with bronchiolitis obliterans.

OBJECTIVE

The aim was to establish immunologic associations by coexistence of Castleman tumor, myasthenia gravis, and bronchiolitis obliterans and to evaluate the treatment modalities.

METHODS

Clinical studies included computed tomography of the mediastinum, computed tomography and magnetic resonance imaging of the abdominal cavity, and quantitative electromyography. Direct and indirect immunofluorescence on various substrates, immunoblot analysis, immunoprecipitation, and specific enzyme-linked immunosorbent assay using recombinant desmogleins (Dsg) were performed as immunologic assays.

RESULTS

Direct and indirect immunofluorescence including rat bladder showed intercellular antibodies. Immunoblotting disclosed antibodies to envoplakin (210 kd protein) and periplakin (190 kd protein); in addition, immunoprecipitation detected antibodies to desmoplakin I (250 kd protein). Antibodies to Dsg3 (pemphigus vulgaris antigen) were detected by specific enzyme-linked immunosorbent assay. Myasthenia gravis was controlled by drugs; however, mucocutaneous changes were not fully responsive to corticosteroids and cyclophosphamide pulses, cyclosporine, and intravenous immunoglobulins. The surgical removal of Castleman tumor did not change the course of the disease. The fatal outcome was the result of bronchiolitis obliterans that occurred after the surgery and was only transitionally controlled by plasmapheresis.

CONCLUSION

This is the first case of paraneoplastic pemphigus associated with Castleman tumor, myasthenia gravis, and bronchiolitis obliterans. Despite a benign character of the tumor the patient died, as do all patients with bronchiolitis obliterans. Massive plasmapheresis has only a transient effect. We confirmed the presence of antibodies to Dsg 3, in addition to the set of specific paraneoplastic pemphigus antibodies against various proteins of plakin family.

Pemphigus and bullous pemphigoid

Pemphigus and bullous pemphigoid are distinct autoimmune blistering diseases that are characterised by the presence of autoantibodies directed against specific adhesion molecules of the skin and mucous membranes. The comparison and contrast of molecular mechanism of blister formation of these two diseases provide a rational diagnostic and therapeutic approach to affected patients.

Autoimmunity against desmosomal cadherins in pemphigus

Pemphigus is a unique and interesting autoimmune disease, in which autoantibodies play a major pathogenic role and cause blister formation. Several questions raised from clinical observation in pemphigus have been answered with logic at the molecular level owing to recent remarkable progress in research in the field of pemphigus. The clinical phenotype of classic pemphigus, pemphigus vulgaris (PV) and pemphigus foliaceus (PF), is defined by anti-desmoglein autoantibody profile. Sera containing anti-Dsg3 IgG alone cause mucosal dominant PV with limited skin involvement. Sera containing both anti-Dsg3 and anti-Dsg1 cause mucocutaneous PV, which affects both the skin and mucous membrane. Sera containing only anti-Dsg1 cause PF, which shows cutaneous but no mucosal involvement. In herpetiform pemphigus (HP) most sera recognize Dsg1 and the rest of them recognize Dsg3, indicating that HP is a clinical variant of PF or PV. Patients with paraneoplastic pemphigus (PNP) have autoantibodies against multiple molecules. Now we know that they have autoantibodies against all members of the plakin family, which are cytoplasmic proteins and include desmoplakin, BPAG1, envoplakin, periplakin, and plectin. Cell surface target antigens of PNP, which blister-inducing pathogenic autoantibodies attack, were finally discovered to be Dsg3 and Dsg1. Therefore, PNP is characterized as an autoimmune disease against plakin molecules and desmogleins. Autoimmune targets of IgA pemphigus are likely more heterogeneous than originally thought. So far, desmocollin 1, Dsg3, and Dsg1 are known as their target antigens. Thus, pemphigus has become one of well-characterized tissue-specific autoimmune diseases. Pemphigus will be a good model disease in the next century to address the central issue of autoimmune disease and basic immunology; why and how do patients with autoimmune diseases start to recognize self as non-self?

Periplakin and envoplakin are target antigens in canine and human paraneoplastic pemphigus

BACKGROUND

On the basis of clinical and histopathologic similarities to human paraneoplastic pemphigus (PNP), we recently identified the first case of PNP in a nonhuman species, the dog.

OBJECTIVE

To determine a similar pathogenesis in both species, the present study aimed to define whether common antigens are targeted in dog and man.

METHODS

Canine and human PNP sera were used in parallel to immunoprecipitate 14C-labeled human keratinocyte antigens. The immunoreactive proteins were then identified by immunoprecipitation of canine keratinocyte extracts with specific antibodies to the antiplakin family members follwed by immunoblot analysis using canine and human PNP sera.

RESULTS

Protein bands of 210, 190, 170, and 130 kd were identified in dogs and humans. In both species, envoplakin and periplakin were demonstrated as antigens. Anti-desmoglein 3 antibodies could not be demonstrated in canine PNP, but in human PNP.

CONCLUSION

These results demonstrate that canine PNP closely correlates to the human counterpart and may therefore represent an excellent model for the human disease.

The new pemphigus variants

Pemphigus describes a group of autoimmune diseases characterized by blisters and erosions of the skin and mucous membranes, acantholysis by histology, and autoantibodies directed against epidermal cell surface components. Since the early 1970s, the following new clinical variants of pemphigus have been reported: pemphigus herpetiformis, IgA pemphigus, and paraneoplastic pemphigus. In recent years, significant data have been obtained from laboratory investigation on these rare and atypical variants, especially regarding their specific target antigens. We review these variants, their clinical presentations, histologic findings, immunopathology, target antigens, theories of pathogenesis, treatment modalities, and clinical courses.

Paraneoplastic pemphigus with fatal pulmonary involvement in a woman with a mesenteric Castleman tumour

A 42-year-old woman presented with oral and labial erosions, conjunctivitis, facial rash and lichenoid erythematous papules on the trunk. Paraneoplastic pemphigus (PNP) was suspected, and a search for a neoplasm revealed an intra-abdominal Castleman tumour sized 7 x 5 x 6 cm. After removal of the Castleman tumour, the skin and mucosal inflammation gradually subsided over the next 12 months. However, due to irreversible pulmonary involvement the patient died of intractable respiratory distress 2 years after the onset of the disease. Systemic corticosteroids, azathioprine, cyclophosphamide, high-dose intravenous immunoglobulins and thalidomide were ineffective. The diagnosis of PNP was confirmed by keratinocyte antigen immunoprecipitation with the patient's serum.

Human autoantibodies against HD1/plectin in paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease that occurs in association with underlying neoplasms. PNP patients develop characteristic autoantibodies directed against multiple antigens, mostly identified as members of the plakin family of cytoplasmic proteins (desmoplakin I and II, bullous pemphigoid antigen I, envoplakin, and periplakin). HD1/plectin, another member of the plakin family, has not previously been detected in the characteristic PNP antigen complex, which may relate to practical difficulties associated with its large size (molecular weight approximately 500 kDa). In this study, a combination of immunoprecipitation and immunoblot is used to demonstrate that HD1/plectin is also recognized by sera from PNP patients. Thirteen of 16 PNP sera tested were positive for HD1/plectin compared with none of 43 control sera (11 pemphigus vulgaris, 11 pemphigus foliaceus, 11 bullous pemphigoid, and 10 normal individuals). Combined with our recent finding that desmoglein 3 and desmoglein 1 are cell surface target antigens in PNP, this demonstration of plectin/HD1 as another component of the antigen complex in PNP confirms that PNP is an autoimmune disease against desmoglein and plakin family molecules.

[Autoimmune bullous skin diseases]

INTRODUCTION

Important advances have been made in the pathogenesis of autoimmune bullous skin diseases during the last 10 years. The aim of this review is to describe new types of autoimmune bullous skin diseases and to summarize progresses in the pathogenesis and treatment of these diseases.

CURRENT KNOWLEDGE AND KEY POINTS

Paraneoplastic pemphigus (PNP) is a new type of pemphigus, distinct from pemphigus vulgaris (PV) and pemphigus foliaceus (PF). It has both clinical and histological features of pemphigus, bullous pemphigoid (BP), erythema multiforme, and lichen planus, in patients with lymphoma. Numerous clinical types of autoimmune bullous skin diseases of the dermal epidermal junction have also been described. Analysis of patients' serum by immunoblotting and immunoprecipitation allowed the identification of target antigens of most of these diseases: PV and PF are due to the production of autoantibodies directed against adhesion molecules (desmoglein 1 and 3) that belong to the cadherin family. In PNP, autoantibodies are directed against plakins, a new family of desmosomal plaque proteins. BP, CP and pemphigoid gestationis are characterized by the production of autoantibodies mainly directed against two hemidesmosomal proteins: BPAG1 and BPAG2. The mortality rate of autoimmune bullous skin diseases is estimated between 10 and 40%, mainly due to infections and cardiovascular diseases. The potential interest of the first use of adjuvant therapies in addition to corticosteroids has not been demonstrated yet.

FUTURE PROSPECTS AND PROJECTS

Due to the numerous side-effects of oral corticosteroids, many therapeutic trials are aimed at finding other treatments for the management of these diseases. Topical corticosteroids could be effective in BP, and even in some cases of pemphigus. New treatments using specific immunoadsorption of pathogenic autoantibodies with recombinant proteins will probably be available in the future.

Paraneoplastic pemphigus as the presenting symptom of a lymphoma of the tongue

A patient is described who initially presented with an acrovesicular eczema which subsequently developed into erythema multiforme with histopathological features of bullous pemphigoid. Although the various laboratory studies pointed to the diagnosis of paraneoplastic pemphigus (PNP), the underlying neoplasm was not detected until 6 months later, when the biopsies of an oral lesion showed the presence of an underlying non-Hodgkin lymphoma.

Paraneoplastic pemphigus: a review

Paraneoplastic pemphigus (PNP) is a relatively recently described autoimmune disorder, distinguished from pemphigus vulgaris or foliaceus by specific clinical, histologic and immunologic criteria. In the present review, 18 cases of paraneoplastic pemphigus reported so far are discussed. The polymorphism, extent and persistence of skin and mucosal lesions are discussed while the problems of differential diagnosis and the significance of the associated neoplasms are also stressed. The underlying malignancy in the majority of the cases has been of lymphoid origin and has preceded the clinical presentation of pemphigus. All patients have had oral and cutaneous lesions. In 66.6% of the patients there was a poor response to therapy.

Antibodies against desmoglein 3 (pemphigus vulgaris antigen) are present in sera from patients with paraneoplastic pemphigus and cause acantholysis in vivo in neonatal mice

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease that occurs in association with underlying neoplasms. Patients with PNP develop characteristic IgG autoantibodies directed against multiple antigens, most of which have been identified as cytoplasmic proteins of the plakin family (desmoplakin I, II, BPAG1, envoplakin, and periplakin). This study identified cell surface target antigens of PNP. We focused on desmoglein (Dsg) 3 and Dsg1, the autoantigens of pemphigus vulgaris and pemphigus foliaceus. ELISA using baculovirus-expressed recombinant Dsgs (rDsg3, rDsg1) has revealed that 25 out of 25 PNP sera tested were positive against Dsg3 and 16 of 25 were positive against Dsg1. All of 12 PNP sera tested immunoprecipitated Dsg3. Removal of anti-Dsg3 autoantibodies by immunoadsorption was sufficient to eliminate the ability of PNP sera to induce cutaneous blisters in neonatal mice in vivo. Furthermore, anti-Dsg3-specific antibodies that were affinity purified from PNP sera were proven to be pathogenic and caused blisters in neonatal mice. These findings indicate that Dsg3 and Dsg1 are the cell surface target antigens in PNP and that IgG autoantibodies against Dsg3 in PNP sera play a pathogenic role in inducing loss of cell adhesion of keratinocytes and causing blister formation.

The members of the plakin family of proteins recognized by paraneoplastic pemphigus antibodies include periplakin

Sera of patients with paraneoplastic pemphigus (PNP) characteristically immunoprecipitate five proteins, observations confirmed with the sera examined in this study. The proteins characterized thus far as autoantigens in PNP all belong to the plakin family of proteins and include desmoplakin, the 230 kDa bullous pemphigoid antigen, and envoplakin. The pattern of bands precipitated from metabolically labeled human keratinocyte extracts by each PNP serum was different, suggesting varying titers of antibodies against unique epitopes in various plakin family members. To further characterize this PNP antibody response, we produced fusion proteins of the homologous tail region of five plakin family members, including the recently cloned periplakin. Immunoblotting of equal amounts of each plakin tail-glutathione S-transferase fusion protein with PNP sera revealed a strong reaction with the envoplakin tail domain. Each sera also recognized periplakin, and certain sera recognized desmoplakin and plectin, and, weakly, bullous pemphigoid antigen 1. PNP sera were affinity purified with periplakin and envoplakin tail fusion proteins. Immunoprecipitation and immunoblotting with these affinity purified antibodies revealed shared as well as unique epitopes in the tail domains of these plakins. This study indicates that a homologous region in the carboxy-terminus of plakins, including the newly characterized periplakin, serves as an antigenic site in PNP.

Novel non-radioisotope immunoprecipitation studies indicate involvement of pemphigus vulgaris antigen in paraneoplastic pemphigus

We have developed two different novel immunoprecipitation assays in which radioisotopes are not used, and have examined antigens for four cases of paraneoplastic pemphigus (PNP) including three new patients. The PNP sera showed a clear reactivity with transitional epithelia of rat urinary bladder by immunofluorescence, and reacted with a characteristic doublet of the 210 and 190 kD proteins by immunoblotting of normal human epidermal extract, confirming the diagnosis of PNP. In addition, by immunoprecipitation using silver-stain to detect immunoprecipitated proteins, the PNP sera detected the 250, 210 and 190 kD proteins, while control bullous pemphigoid sera detected only the 230 kD bullous pemphigoid antigen. Furthermore, with another immunoprecipitation using cell surface biotinylation, three of the four PNP sera specifically reacted with the 130 kD pemphigus vulgaris antigen (Dsg3), indicating that pemphigus vulgaris antigen may be involved in PNP. This reactivity was further suggested by the immunoblot analysis using recombinant pemphigus vulgaris antigen. In future, these non-radioisotope immunoprecipitation assays should become a useful tool not only to unravel the complex situation for the PNP antigens, but also to study antigens in other autoimmune bullous skin diseases.

Molecular biological aspects of acquired bullous diseases

Bullous diseases of the oral mucosa and skin were originally classified on the basis of clinical and histological criteria. The discovery of autoantibodies in some of these patients and the introduction of molecular biology have resulted in a new understanding of the pathological mechanisms of many of the bullous lesions. In this article, updated topics of the immune-mediated bullous lesions which involve oral mucosa and skin are reviewed. Pemphigus antigens, which are desmosomal-associated proteins and belong to the cadherin superfamily of cell adhesion proteins, have been isolated, and their genes have been cloned. The antigens which react with autoantibodies from patients with bullous pemphigoid, cicatricial pemphigoid, acquired epidermolysis bullosa, and linear IgA disease are all proteins of the hemidesmosome basement membrane complex. Interestingly, most of the antigens also appear to be the target for mutations seen in patients with the inherited type of epidermolysis bullosa in which bullous lesions are a prominent clinical feature.

Localized mucosal involvement and severe pulmonary involvement in a young patient with paraneoplastic pemphigus associated with Castleman's tumour

We describe a 19-year-old female patient who developed recurrent ulcerations limited to the orogenital mucosa for the last 3 years. She also developed dyspnoea 5 months after the onset of the orogenital lesions. Castleman's tumour of the retroperitoneum was found incidentally during routine physical examination. The diagnosis of paraneoplastic pemphigus (PNP) was made by pathological and immunological studies. The orogenital ulceration responded well to corticosteroid therapy, but severe bronchiolitis obliterans progressed despite intensive care. The patient eventually died from respiratory failure. This case demonstrates the diversity of clinical features of paraneoplastic pemphigus.

Necrotizing tracheobronchitis with progressive airflow obstruction associated with paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) is an autoimmune disease associated with leukemia and non-Hodgkin's lymphoma. A patient with stage IVB poorly differentiated lymphocytic lymphoma developed characteristic upper and lower airway involvement with profound mucocutaneous erosion and tracheobronchial epithelial desquamation. Immunofluorescence testing confirmed autoantibody deposition along the basement membrane of bronchial epithelium. Disruption of the cellular adhesion mechanisms, including desmosomes, hemidesmosomes, and possibly the integrin subunits, is presumed to have led to disruption and desquamation of the tracheobronchial epithelial barrier, severe obstruction of the airways and hypoxia, and possibly bacterial superinfection. As far as can be determined, the feature of airflow obstruction occurring in association with PNP has not been described. Physicians should be aware that these complications of PNP may rapidly lead to hypoxic respiratory failure and death.

Mucocutaneous features of autoimmune blistering diseases

This review will describe adult onset mucocutaneous/autoimmune diseases that involve defects in cell-to-cell, cell-to-matrix, or cell-to-basement membrane adhesion. Included in this group are pemphigus, cicatricial pemphigoid, linear IgA bullous dermatosis, epidermolysis bullosa acquisita, and bullous systemic lupus erythematous. Detection and treatment of blistering disorders that manifest early in the oral cavity may prevent widespread involvement of skin. During the past few years, targets of autoantibodies have been clarified and new targets have been identified, allowing better understanding of the pathophysiology involved in these diseases. New information about more effective regimens with fewer side effects has also been obtained, presenting new treatment options. Clinical manifestations and management of these disorders will be described as well as histopathologic, ultrastructural, and immunopathologic studies that distinguish each disorder and facilitate diagnosis and treatment.

cDNA cloning of the 210-kDa paraneoplastic pemphigus antigen reveals that envoplakin is a component of the antigen complex

Although the 210 and 190-kDa proteins are the most frequently detected antigens reacting with sera of patients with paraneoplastic pemphigus (PNP) in immunoblot analysis, there is still uncertainty as to the nature of these PNP antigens. To isolate and characterize a cDNA clone encoding the 210-kDa PNP antigen, we screened a human keratinocyte lambda gt 11 cDNA expression library by the immunoperoxidase method with serum IgG from a PNP patient. The IgG used for the immunoscreening of a keratinocyte cDNA expression library recognized 210- and 190-kDa antigens by immunoblotting. A single clone, called here the PNP clone, producing a fusion protein that reacted strongly with the patient's IgG, was further characterized. Only the PNP patient's IgG, but not IgG from a normal control, pemphigus foliaceus, or pemphigus vulgaris patients, bound the plaques of this positive clone. Furthermore, PNP IgG affinity purified on plaques of this clone, but not unrelated clones, bound to keratinocyte cell surfaces by immunofluorescence and reacted with the 210-kDa PNP antigen by immunoblotting. EcoRI digestion of the clone's cDNA insert demonstrated a 1.4-kbp fragment. This cDNA insert was placed into a M13 mp 18 vector and sequenced. Sequence analysis revealed that the cDNA insert of the PNP clone encodes a part of the central rod domain and the COOH-terminal C domain of envoplakin, a newly defined precursor of the cornified envelope that is homologous to desmoplakin. This result demonstrates that the 210-kDa PNP antigen is envoplakin and PNP is an autoimmune disease that produces autoantibodies against intermediate filament-associated proteins in desmosomes and hemidesmosomes, desmoplakin, bullous pemphigoid antigen 1 (BPAG 1), and envoplakin.