Pemphigus: autoimmune diseases of keratinocyte's adhesion molecules

Diagnosis and management of vulvar Darier disease: A case report

Darier disease is an autosomal dominant disorder with hyperkeratotic papules affecting primarily seborrheic areas of the upper chest, back, forehead, scalp, nasolabial folds, ears, and, less frequently, the oral mucosa. A typical eruption consists of keratotic and crusted skin-colored papules and plaques. Pruritus occurs in 80% of patients, and pain is rare. Lesions can be triggered by exposure to ultraviolet light, heat, or stress. Secondary infections of the lesions are a common complication. A definitive diagnosis is obtained by a biopsy showing histological features such as acantholysis, suprabasal clefts, and "corps rond and grains". Here we present a 37-year-old woman admitted to the gynecology department with pruritic lesions she had noticed on her vulva and perineum for three months. A vulvar biopsy led to the diagnosis of Darier disease. She was referred to the dermatology department and treated with oral acitretin since systemic retinoids are offered as the first-line treatment of the disease.

New and emerging vaccination strategies for prevention and treatment of dermatological diseases

Accelerated by the rapid advancements of our understanding of the molecular and cellular pathology of diseases and of the components and mechanisms of cellular and humoral immune responses, new vaccination strategies are being developed and explored for treatment and prevention of infectious diseases, cancer, autoimmune disorders and allergies. Many newly developed vaccination strategies are already in clinical trials, some with very promising results. Although most of these strategies are still at very early stages of their development, it is foreseeable that vaccination will evolve to play an important role in prevention, treatment and management of all the above classes of diseases.

Bullous skin diseases: classical types of autoimmune diseases

The prototypic bullous skin diseases, pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid, are characterized by the blister formation in the skin and/or oral mucosa in combination with circulating and deposited autoantibodies reactive with (hemi)desmosomes. Koch's postulates, adapted for autoimmune diseases, were applied on these skin diseases. It appears that all adapted Koch's postulates are fulfilled, and, therefore, these bullous skin diseases are to be considered classical autoimmune diseases within the wide and expanding spectrum of autoimmune diseases.

Translational Mini-Review Series on B Cell-Directed Therapies: The pathogenic role of B cells in autoantibody-associated autoimmune diseases--lessons from B cell-depletion therapy

B cell depletion therapy with rituximab (BCDT) is a licensed treatment for rheumatoid arthritis and has shown promising results in the treatment of severe, refractory patients with other autoantibody-associated autoimmune diseases (AAID). The exact role that B cells play in the pathogenesis of AAID and consequently the mechanisms by which BCDT is effective are not known. The two more widely discussed hypotheses are that BCDT is effective because it removes the precursors of plasma cells producing pathogenic autoantibody species, or because it depletes a critical mass of autoreactive B cell clones that present antigen to pathogenic autoreactive T cells. This review will focus on the effects of BCDT and whether the response of patients with AAID to BCDT could be due ultimately to its effects on autoantibodies. A better knowledge of the main role that B cells play in the pathogenesis of the different diseases and a better understanding of the most likely mechanism of relapse following an earlier response to BCDT would help to guide further developments of B cell targeting therapies and potentially increase the chance of designing a protocol that could induce a long-term remission.

Prédisposition aux infections des malades ayant un pemphigus

INTRODUCTION

The relation between pemphigus and infection is complex. The aim of this work was to determine the frequency and impact of infection as well as the factors associated with it among our patients with pemphigus.

METHODS

This retrospective case series examined records of patients with pemphigus admitted to the dermatology unit of Ibn Sina University Hospital of Rabat between 1989 and 2004. We compared the patients with and without infections as well as the patients with and without severe bacterial infections according to patient profile and outcome. The principal outcome measure was death and the secondary measure, duration of hospitalization.

RESULTS

Of the 141 patients with pemphigus included in our study, 68% developed an infection. Infections were bacterial in 52% of cases, fungal in 50%, herpetic in 19% and parasitic in 1.5%. They were associated with diabetes mellitus and immunosuppressive drugs. Severe bacterial infection was frequent in patients with diabetes and rare in those treated with corticosteroids or with pemphigus foliaceous. Death occurred significantly more often among infected subjects (p=0.01), especially those with severe bacterial infections (p<0.001). Hospitalization was slightly longer among patients with infections (p=0.01) but shorter in cases of severe bacterial infections (p=0.004).

DISCUSSION

Our study confirms the predisposition to all types of infection among patients with pemphigus, as well as the undeniable role its treatment plays in promoting infection. Severe bacterial infections were most often contracted before hospitalization. The literature reports a wide variety of infections, with pemphigus-herpes documented most often. Prevention and management require hygienic measures as well as early diagnosis and treatment of pemphigus and infections. Preventive treatment may be considered, but studies are needed to define the patients who might benefit from it.

Apoptotic mechanism in pemphigus autoimmunoglobulins-induced acantholysis--possible involvement of the EGF receptor

Pemphigus is an autoimmune cutaneous disease characterized by circulating autoantibodies that cause blistering and erosions on skin and mucous membranes. Circulating autoantibodies bind to epidermal cell membrane and cause cell-cell detachment (acantholysis), leading to epidermal tissue damage and cell death. The principal target of pemphigus vulgaris autoantibodies (PV-IgG) is desmosomal cadherin desmoglein 3 (Dsg3), a constituent of desmosomes, mediating cell-cell adhesion. Several hypotheses for the mechanisms of acantholysis induction by PV-IgG exist, but the actual mechanism is not clear as yet. We have previously reported on apoptosis induction in PV-IgG-mediated epidermal tissue and cell damage as a possible mechanism of acantholysis and cell death (Wang et al. 2004, Apoptosis, 9:131-143). In this study we investigated the involvement of the EGFR and intracellular signal transduction pathways in the PV-IgG-induced apoptosis. We show here that PV-IgG induced activation/autophosphorylation of EGFR in cultured keratinocytes in vitro. The specific tyrosine kinase inhibitor AG1478 abrogated EGFR autophosphorylation, cell death, FasL appearance and acantholysis, all induced by PV-IgG, in parallel, confirming the involvement of EGFR in this Fas apoptotic cascade. Activation of EGFR was followed by phosphorylation of its downstream substrates, MAP kinase ERK and transcription factor c-Jun, and internalization of EGFR. Pharmacological inactivation of the EGFR and ERK kinase activities, by use of specific inhibitors AG1478 and PD98059 respectively, blocked PV-IgG-induced phosphorylation of EGFR, ERK and c-Jun and cellular apoptosis, measured by flow cytometry and caspase 3 activity. Prolonged activation of EGFR by PV-IgG led to dramatic internalization of this receptor, possibly reducing the ability of the cell to perform survival signals. This suggests that activation of EGFR, followed by its internalization, is pivotal for intracellular apoptotic signal transduction via ERK/c-Jun pathways, leading to acantholysis. Our experimental data indicate that the EGFR is instrumental in transducing apoptotic/acantholytic signals in keratinocytes cultures in response to PV-IgG treatment. The acantholytic effect caused by PV-IgG binding to cell surface receptors begins with and depends on cell surface receptor (EGFR) activation of intracellular signaling pathways (ERK pathway) and apoptosis induction (FasR pathway), which later lead to major cell-cell separation (acantholysis) and cell death.

Proteomic analysis of the autoantibody response following immunization with a single autoantigen

In most autoimmune diseases, the autoantibody response is directed against several antigens of the target organ whose identification is crucial for understanding the physiopathological process. Thus, technologies allowing a characterization of the whole autoantibody pattern of both human and experimental autoimmune diseases are required. Here we have used immunoproteomic analysis of human epidermal extracts to characterize the diversity of the anti-desmosome antibody response induced in normal mice immunized with desmoglein 1, the major autoantigen of pemphigus foliaceus, an autoimmune blistering skin disease. In particular, this analysis enables us to characterize the binding properties of anti-desmosome mAbs derived from these mice and to show that the autoantibody response induced upon immunization with a single autoantigen targets different epidermal autoantigens with a pattern similar to that observed in certain variety of human pemphigus.

Pemphigus foliaceus IgG causes dissociation of desmoglein 1-containing junctions without blocking desmoglein 1 transinteraction

Autoantibodies against the epidermal desmosomal cadherins desmoglein 1 (Dsg1) and Dsg3 have been shown to cause severe to lethal skin blistering clinically defined as pemphigus foliaceus (PF) and pemphigus vulgaris (PV). It is unknown whether antibody-induced dissociation of keratinocytes is caused by direct inhibition of Dsg1 transinteraction or by secondary cellular responses. Here we show in an in vitro system that IgGs purified from PF patient sera caused cellular dissociation of cultured human keratinocytes as well as significant release of Dsg1-coated microbeads attached to Dsg-containing sites on the keratinocyte cellular surface. However, cell dissociation and bead release induced by PF-IgGs was not caused by direct steric hindrance of Dsg1 transinteraction, as demonstrated by single molecule atomic force measurements and by laser trapping of surface-bound Dsg1-coated microbeads. Rather, our experiments strongly indicate that PF-IgG-mediated dissociation events must involve autoantibody-triggered cellular signaling pathways, resulting in destabilization of Dsg1-based adhesive sites and desmosomes.

Pénfigo

Pemphigus is an infrequent, organ-specific, autoimmune bullous disease, which affects the skin, mucous membranes and appendages. Histopathologically, it is characterized by acantholysis. Pemphigus has classically been divided into two major groups, pemphigus vulgaris and pemphigus foliaceus, with their respective clinical variants pemphigus vegetans and pemphigus erythematosus. In recent years, new variants of pemphigus have been described: paraneoplastic pemphigus, IgA pemphigus and pemphigus herpetiformis. This article reviews the epidemiology, etiopathogenesis, clinical symptoms, diagnosis, treatment and prognosis of pemphigus. Advances in molecular biology techniques have made it possible to more precisely identify the different antigens against which antibodies are directed, and to fine-tune ELISA diagnostic techniques. Treating pemphigus vulgaris and foliaceus with general steroids has modified their prognosis; it is estimated that mortality in recent decades is less than 10 %. Managing the clinical complications that appear during the evolution of the pemphigus has contributed to reducing morbidity and mortality.

Avancées moléculaires dans la physiopathologie des maladies bulleuses autoimmunes

Autoimmune blistering skin diseases are characterized by the production of autoantibodies directed against adhesive structures of the skin. These organ specific autoimmune diseases included pemphigus in which autoantibodies target proteins of the desmosomal complex, and subepidermal autoimmune diseases characterized by autoantibodies directed against structural proteins of the dermoepidermal junction. Binding of autoantibodies to their targets induces a loss of adhesion between keratinocytes in pemphigus and alterations of the dermoepidermal junction in subepidermal autoimmune diseases. Progresses during the last twenty years had allowed the identification of target autoantigens and the characterization of their adhesive functions, a better understanding of the pathogenesis of these diseases and the development of new diagnostic tools.

Clinicopathologic attributes of common geriatric dermatologic entities

Certain dermatologic lesions may initially present or be more commonly ascribed to the elderly. These disorders encompass a diverse array of etiologically unrelated degenerative, autoimmune, idiopathic, and neoplastic conditions that may dramatically impact the quality of life and produce significant morbidity and mortality. As the population ages, a more complete understanding of the clinical and histopathologic features unique to the geriatric dermatologic patient is essential.

An evaluation of the usefulness of mycophenolate mofetil in pemphigus

BACKGROUND

Pemphigus is a group of autoimmune blistering diseases of the skin and/or mucous membranes requiring management with immunosuppressive therapy. The optimal therapeutic regimen would rapidly induce remission and maintain effectiveness with minimal adverse effects in the long term.

OBJECTIVES

The present study describes our experience of the addition of mycophenolate mofetil (MMF) to prednisolone in the management of severe, refractory pemphigus.

METHODS

Patients with active, refractory pemphigus were treated with MMF. Our series included 12 cases of pemphigus vulgaris, four cases of pemphigus foliaceous and one case of paraneoplastic pemphigus. All patients were monitored to assess disease control and mycophenolate toxicity.

RESULTS

Of the 17 cases, MMF has been of benefit to 12. MMF was well tolerated and there were no treatment withdrawals because of safety concerns.

CONCLUSIONS

We found that MMF permitted a reduction in prednisolone dosage without disease relapse.

The future of vaccination as a treatment strategy in dermatological diseases

Vaccination approaches are increasingly explored as means for both prevention and therapy of skin diseases. These development are boosted by the rapidly accumulating knowledge of the molecular and cellular bases of these disease and the antigens involved, on the one hand, and of the components and mechanisms of cellular and humoral immune responses, on the other. In a number of cases these newly developed vaccination strategies are already tested in clinical trials. Although most of them are still in very early stages of the development, it is foreseeable that vaccination will emerge as an important option for prevention and treatment of infectious skin diseases as well as of cancer, allergies and maybe, auto-immune disorders.

Tunisian endemic pemphigus foliaceus is associated with desmoglein 1 gene polymorphism

Desmoglein 1 is the target antigen and probably the initiating immunogen of the autoantibody response in pemphigus foliaceus (PF), a blistering autoimmune skin disease. We previously showed that the desmoglein 1 gene (DSG1) is polymorphic and that one of its variants is associated with the sporadic form of PF observed in France. Herewith, we report, based on a case-control analysis, that the same DSG1 polymorphism participates in susceptibility to the endemic form of PF seen in Tunisia and, thus, show that common genetic factors govern the breakage of tolerance to desmoglein 1 in different epidemiological and environmental situations.

Epistasis between DSG1 and HLA class II genes in pemphigus foliaceus

Pemphigus foliaceus (PF) is a rare and severe cutaneous autoimmune disease caused by autoantibodies directed against desmoglein 1 (DSG1), a desmosomal adhesion glycoprotein. We previously showed that the DSG1 gene is polymorphic and that a coding synonymous T/C single nucleotide polymorphism at position 809 is associated with PF. To determine whether the disease occurred as a consequence of complex genetic interactions, we simultaneously examined the contribution of major histocompatibility complex (MHC) class II and DSG1 polymorphisms to PF susceptibility. Our analysis performed in 31 PF patients and 84 healthy controls first confirmed the previously reported common DRB1*04 and DRB1*14 genetic background in PF and individualized DRB1*0102, DRB1*0402 and DRB1*0406, and DRB1*1404 as susceptibility MHC class II alleles in French Caucasian PF patients. It also showed that the C/C(809) genotype was associated with PF. Combined analysis of HLA class II and DSG1 polymorphisms with several distinct statistical methods including logistic regression, showed that the DRB1*04 allele and the C/C(809) genotype interact to confer a higher susceptibility to PF. These data demonstrate the role of epistasis between individual genes in PF susceptibility and illustrate the genetic complexity of organ-specific autoimmune diseases.

Pemphigus is not associated with allotypic markers of immunoglobulin kappa

The kappa light chain constant region of immunoglobulins bears polymorphic markers involved in susceptibility to various autoimmune diseases. To determine whether it also contributes to the occurrence of pemphigus, a group of autoimmune blistering skin diseases owing to pathogenic autoantibodies, the genotypic frequencies of Km allotypes were evaluated in patients with pemphigus foliaceus or pemphigus vulgaris and ethnically-matched healthy controls in both Tunisia and France. No difference in the distribution of Km genotype or allele frequencies was observed between patients and controls in either countries. Therefore, Km allotypes do not appear to constitute a genetic factor contributing to pemphigus.