Immune modulation in pemphigus vulgaris: role of CD28 and IL-10

Common Denominators in the Immunobiology of IgG4 Autoimmune Diseases: What Do Glomerulonephritis, Pemphigus Vulgaris, Myasthenia Gravis, Thrombotic Thrombocytopenic Purpura and Autoimmune Encephalitis Have in Common?

IgG4 autoimmune diseases (IgG4-AID) are an emerging group of autoimmune diseases that are caused by pathogenic autoantibodies of the IgG4 subclass. It has only recently been appreciated, that members of this group share relevant immunobiological and therapeutic aspects even though different antigens, tissues and organs are affected: glomerulonephritis (kidney), pemphigus vulgaris (skin), thrombotic thrombocytopenic purpura (hematologic system) muscle-specific kinase (MuSK) in myasthenia gravis (peripheral nervous system) and autoimmune encephalitis (central nervous system) to give some examples. In all these diseases, patients’ IgG4 subclass autoantibodies block protein-protein interactions instead of causing complement mediated tissue injury, patients respond favorably to rituximab and share a genetic predisposition: at least five HLA class II genes have been reported in individual studies to be associated with several different IgG4-AID. This suggests a role for the HLA class II region and specifically the DRβ1 chain for aberrant priming of autoreactive T-cells toward a chronic immune response skewed toward the production of IgG4 subclass autoantibodies. The aim of this review is to provide an update on findings arguing for a common pathogenic mechanism in IgG4-AID in general and to provide hypotheses about the role of distinct HLA haplotypes, T-cells and cytokines in IgG4-AID.

Chromosome 2q33genetic polymorphisms in Tunisian endemic pemphigus foliaceus

BACKGROUND

Several studies have suggested that polymorphisms within genes encoding T-lymphocyte immune regulating molecules: CD28, CTLA-4, and ICOS, may alter the signaling process and subsequently could be involved in susceptibility to a broad spectrum of autoimmune diseases.

METHODS

This study aimed to replicate associations between common polymorphisms in the 2q33.2 cluster and susceptibility to pemphigus foliaceus (PF) in the Tunisian population. We investigated seven polymorphisms: rs3116496 and rs1879877 (CD28), rs231775, rs3087243, and (AT)n repeat (CTLA4); rs11889031 and rs10932029 (ICOS) in a case-control study which enrolled 106 Tunisian PF patients and 205 matched healthy controls.

RESULTS

We confirmed the associations with CTLA4((AT)13 , p = 0.00137, OR = 3.96 and (AT)20 , p = 0.008, OR = 5.22; respectively) and ICOS genes (rs10932029>CT, p = 0.034, OR = 2.12 and rs10932029>TT, p = 0.04 and OR = 0.41).

CONCLUSION

Our results indicate that susceptibility to PF is located in the proximal and the distal 3' flanking region of the CTLA4/ICOS promoter. These findings may open avenues to the treatment of patients with biological drugs targeting CTLA4/ICOS molecules, in a personalized manner to achieve more effective treatment.

B-cell targeted therapies in pemphigus

Pemphigus is a rare autoimmune disease of the skin, characterized by autoantibodies targeting adhesion proteins of the epidermis, in particular desmoglein 3 and desmoglein 1, that cause the loss of cell-cell adhesion and the formation of intraepidermal blisters. Given that these autoantibodies are both necessary and sufficient for pemphigus to occur, the goal of pemphigus therapy is the elimination of autoreactive B-cells responsible for autoantibody production. Rituximab, an anti-CD20 monoclonal antibody, was the first targeted B-cell therapy approved for use in pemphigus and is now considered the frontline therapy for new onset disease. One limitation of this treatment is that it targets both autoreactive and non -autoreactive B-cells, which accounts for the increased risk of serious infections in treated patients. In addition, most rituximab-treated patients experience disease relapse, highlighting the need of new therapeutic options. This review provides a concise overview of rituximab use in pemphigus and discusses new B-cell and antibody-directed therapies undergoing investigation in clinical studies.

Skin Barrier and Autoimmunity-Mechanisms and Novel Therapeutic Approaches for Autoimmune Blistering Diseases of the Skin

One of the most important functions of the skin besides regulating internal body temperature includes formation of the barrier between the organism and the external environment, hence protecting against pathogen invasion, chemical and physical assaults and unregulated loss of water and solutes. Disruption of the protective barrier is observed clinically in blisters and erosions of the skin that form in autoimmune blistering diseases where the body produces autoantibodies against structural proteins of the epidermis or the epidermal-dermal junction. Although there is no cure for autoimmune skin blistering diseases, immune suppressive therapies currently available offer opportunities for disease management. In cases where no treatment is sought, these disorders can lead to life threatening complications and current research efforts have focused on developing therapies that target autoantibodies which contribute to disease symptoms. This review will outline the involvement of the skin barrier in main skin-specific autoimmune blistering diseases by describing the mechanisms underpinning skin autoimmunity and review current progress in development of novel therapeutic approaches targeting the underlying causes of autoimmune skin blistering diseases.

Mechanisms of Acantholysis in Pemphigus: Mechanical or Inflammatory?

Pemphigus is a rare autoimmune disease, involving the skin and mucous epithelia, characterized by flaccid blisters and erosions. Histologically, the basic abnormality in all forms of pemphigus is the separation of keratinocytes from one another, a process known as acantholysis. There is direct evidence that autoantibodies against desmoglein, a transmembrane desmosomal component, are critical in its pathogenesis, but the exact mechanism that induces acantholysis is yet unknown. Actually, different studies suggest three possible mechanisms: sterical impedance, intracellular signalling and apoptosis. Understanding these processes should show new therapeutic perspective.

Tannic Acid Induces in vitro Acantholysis of Keratinocytes via IL-1α and TNF-α

The mechanism of acantholysis in pemphigus vulgaris (PV) is an intriguing argument since several chemical mediators are implicated. We previously reported a central role for IL-1α and TNF-α, both able to regulate complement activation and plasminogen activators. Very little is known about what triggers the disease (drugs, viruses or food). In this study, we evaluate the molecular role of tannins in acantholysis. By HPLC chromatography we measured tannic acid (TA) and gallic acid (GA) in blister fluid of 4 groups of patients divided according to their dietary habits, including a regular diet, a diet rich in tannins, a diet free of tannins, and a group of pemphigus patients. Blister fluid was obtained from patients using a suction blister apparatus. We show that people with a diet rich in tannins have increased tannin metabolites (TA and GA) in the skin in respect to controls (tannin-rich diet: GA = 194.52±2.39 nmol/ml; TA = 348.28±1.4 nmol/ml versus tannin-Mediterranean diet: GA = 15.28±1.63 nmol/ml; TA = 22.81±1.68 nmol/ml). PV patients showed similar values to the Mediterranean diet population (PV patients: GA = 95.8±1.97 nmol/ml; TA = 199.09±4.15 nmol/ml versus Mediterranean diet: GA = 83.53±2.35 nmol/ml; TA = 195.1±2.50 nmol/ml). In an in vitro acantholysis system using TA and PV-IgG we show that TA 0.1 mM in NHEK culture is able to induce acantholysis. This effect was able to amplify the acantholytic action of PV-IgG in vitro. A blocking study using anti IL-1α and anti TNF-α antibodies showed a reduction in TA-induced acantholysis. Taken together, these results suggest that a diet rich in tannins could be a trigger in genetically predisposed patients. If these data are confirmed, a complementary diet poor in tannins may be useful in patients affected by PV.

The dual nature of interleukin-10 in pemphigus vulgaris

The immunomodulatory cytokine interleukin-10 (IL-10) plays beneficial but also potentially detrimental roles in inflammation, infection, and autoimmunity. Recent studies suggest a regulatory role for IL-10-expressing B cells in the autoimmune blistering disease pemphigus vulgaris. Here we review the studies on IL-10 in pemphigus vulgaris and discuss the potential pathophysiological significance of these findings in comparison to prior studies of IL-10 in other human conditions. A better understanding of the complex roles of IL-10 in immune regulation may improve our understanding of pemphigus pathogenesis and treatment.

Constructing immunoprofiles to deconstruct disease complexity in pemphigus

The complex etiology of multifactorial diseases such as pemphigus vulgaris complicates mechanistic investigations and confounds current therapeutic approaches. Two major sources contribute to the overall complexity of disease. Biological complexity involves the disruption of multiple immune pathways that underlie autoimmune destruction in the skin. Overlaying this altered immunobiology is clinical complexity that is manifest as heterogeneous presentations of disease. Merging cumulative data on immune dysfunction with the detailed clinical information can be expected to allow the deconstruction of the processes that lead to specific disease presentations. Our group has undertaken comprehensive analyses in stratified patient populations to assign T cell, cytokine, and autoantibody immunoprofiles linked to defined constant and variable clinical parameters. We propose the concept of a "disease array" that is based on a matrix of supporting biological and clinical information that can be used to guide the development of next-generational tools that enhance our ability to diagnose, prognose, and individually treat disease.

T regulatory cells maintain intestinal homeostasis by suppressing γδ T cells

Immune tolerance against enteric commensal bacteria is important for preventing intestinal inflammation. Deletion of phosphoinositide-dependent protein kinase 1 (Pdk1) in T cells via Cd4-Cre induced chronic inflammation of the intestine despite the importance of PDK1 in T cell activation. Analysis of colonic intraepithelial lymphocytes of PDK1-deficient mice revealed markedly increased CD8α(+) T cell receptor (TCR)γδ(+) T cells, including an interleukin-17 (IL-17)-expressing population. TCRγδ(+) T cells were responsible for the inflammatory colitis as shown by the fact that deletion of Tcrd abolished spontaneous colitis in the PDK1-deficient mice. This dysregulation of intestinal TCRγδ(+) T cells was attributable to a reduction in the number and functional capacity of PDK1-deficient T regulatory (Treg) cells. Adoptive transfer of wild-type Treg cells abrogated the spontaneous activation and proliferation of intestinal TCRγδ(+) T cells observed in PDK1-deficient mice and prevented the development of colitis. Therefore, suppression of intestinal TCRγδ(+) T cells by Treg cells maintains enteric immune tolerance.

ICOS Gene Polymorphism May Be Associated with Pemphigus

Background:

Pemphigus is an autoimmune blistering disease mediated by circulating IgG autoantibodies directed against desmogleins 3 and/or 1. As pemphigus is a T cell–mediated disease, one may assume that genetically determined disregulation of costimulatory signal may be involved in its pathogenesis.

Objective:

The aim of the present study was to evaluate the relationship between polymorphisms in genes encoding costimulatory receptors, CTLA4 and ICOS, and pemphigus in the Polish population.

Methods:

The study included 54 patients with pemphigus: 40 with pemphigus vulgaris (PV) and 14 with pemphigus foliaceus (PF). Additionally, 176 healthy unrelated blood donors served as controls. +49A/G CTLA4 and IVS1+173 ICOS polymorphisms were identified using a modified polymerase chain reaction–restriction fragment-length polymorphism.

Results:

Analysis of the frequency of genotypes and alleles of +49A/G CTLA4 gene polymorphism showed no statistically significant differences between the PV and PF patients and the controls. The distribution of genotypes in IVS1+173 ICOS polymorphisms was significantly different in both PV ( p < .01) and PF ( p = .0004) patients when compared to controls. The carriers of the allele C were more frequent in PV or PF in comparison with the control group ( p < .001 for both groups).

Conclusions:

Our results suggest that genetically determined abnormal function of costimulatory receptors in T cells may be associated with the pathogenesis of pemphigus.

TNF-alpha and IL-10 gene polymorphisms show a weak association with pemphigus vulgaris in the Slovak population

BACKGROUND

Pemphigus vulgaris is a rare chronic autoimmune disease of skin and mucous membranes, with several cytokines participating in its development. The role of their gene polymorphisms in susceptibility to the disease is, however, not fully understood.

OBJECTIVE

The aim of our case-control study was to investigate whether some of 22 single nucleotide polymorphisms (SNPs) in 13 cytokine genes (IL-1alpha, IL-1beta, IL-1RI, IL-1Ra, IL-4Ralpha, IL-12, IFN-gamma, TGF-beta1, TNF-alpha, IL-2, IL-4, IL-6 and IL-10) are associated with pemphigus vulgaris in the Slovak population.

METHODS

DNA samples were obtained from 34 pemphigus vulgaris patients and 140 healthy controls of Slovak origin. Cytokine gene SNPs were determined using the polymerase chain reaction with sequence-specific primers (PCR-SSP) method. Results We found a weak association between pemphigus vulgaris and polymorphic variants in TNF-alpha and IL-10 genes only, with haplotypes TNF-alpha-308G/-238G and IL-10 -1082A/-819C/-592C being significantly overrepresented in pemphigus vulgaris patients (TNF-alpha GG: 94.12% vs. 82.86%, P = 0.0216; IL-10 ACC: 44.12% vs. 30.00%, P = 0.0309).

CONCLUSIONS

Our preliminary results suggest that certain TNF-alpha and IL-10 gene polymorphisms might contribute to genetic susceptibility to pemphigus vulgaris; however, their overall impact on disease development will be rather limited.

Unusual thrombotic cardiac complications of Pemphigus vulgaris: a new link?

We are reporting a case of Pemphigus vulgaris with extensive thrombosis of deep veins, pulmonary veins, and cardiac chambers complicated by myocardial infarction. The extensive skin lesions prohibited the administration of thrombolytics and coronary intervention. The patient was treated conservatively with heparin, and oral anticoagulation in addition to steroids and cyclosporine with significant resolution of thrombosis.

Involvement of IL-10 in exhaustion of myeloid dendritic cells and rescue by CD40 stimulation

It has recently been shown that immature dendritic cells (DCs) stimulated by a danger signal undergo transient maturation followed by exhaustion. However, the exact mechanism for this has not been elucidated. In this study, we show that interleukin-10 (IL-10) secreted from transiently matured DCs stimulated by danger signals is responsible for this rapid DC exhaustion. Blocking of the autocrine IL-10 enabled transient mature DCs to maintain the mature phenotype for several days. However, these DCs remained phenotypically unstable because the addition of IL-10 altered the transient mature DCs to exhausted DCs. More importantly, stimulation of DCs by CD40 protected transient mature DCs from IL-10-dependent exhaustion, with the result that mature DCs remained stable in the presence of IL-10. Furthermore, in vivo administration of stable mature DCs pulsed with ovalbumin protein induced antigen-specific cytotoxic T lymphocytes (CTLs) effectively, whereas neither exhausted DCs nor transient mature DCs were able to prime a strong antigen-specific CTL response. These results indicate that DC-T cell engagement via CD40-CD154 is required for stable DC maturation leading to effective CTL induction. Otherwise, DCs stimulated solely by a danger signal are temporarily activated, but then rapidly lose their immune-activating capacity under the influence of autocrine IL-10.

Number II Pemphigus vulgaris

Pemphigus is a group of potentially life-threatening autoimmune diseases characterized by cutaneous and/or mucosal blistering. Pemphigus vulgaris (PV), the most common variant, is characterized by circulating IgG antibodies directed against desmoglein 3 (Dsg3), with about half the patients also having Dsg1 autoantibodies. There is a fairly strong genetic background to pemphigus with linkage to HLA class II alleles and ethnic groups such as Ashkenazi Jews and those of Mediterranean and Indian origin, are especially liable. Oral lesions are initially vesiculobullous but readily rupture, new bullae developing as the older ones rupture and ulcerate. Biopsy of perilesional tissue, with histological and immunostaining examination are essential to the diagnosis. Serum autoantibodies to either Dsg1 or Dsg3 are best detected using both normal human skin and monkey oesophagus or by enzyme-linked immunosorbent assay. Before the introduction of corticosteroids, PV was typically fatal mainly from dehydration or secondary systemic infections. Current treatment is largely based on systemic immunosuppression using corticosteroids, with azathioprine or other adjuvants or alternatives but newer therapies with potentially fewer adverse effects, also appear promising.

Cytokine polymorphisms in patients with pemphigus

The aim of this study was to assess whether tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1) and interleukin-10 (IL-10) polymorphisms are among the factors influencing the development of pemphigus. Whole blood from 20 patients with pemphigus and 24 control subjects was taken. Genomic DNA was obtained and cytokine genotyping for IL-10 (-1082 G/A; -819 C/T), TGFB1 (codon 10 C/T, codon 25 G/C) and TNFA (-308 G/A) was performed using the ARMS-PCR method. The distribution of IL-10 (-819) alleles was significantly different between the pemphigus and control groups (P=0.009). In particular, allele T was associated with the disease (OR 3.291, 95% CI 1.350-8.020). Similar results were observed when only pemphigus vulgaris (PV) patients were analyzed (P=0.012, OR 3.410, 95% CI 1.346-8.639). An increased frequency of the low producer IL-10 haplotype (-1082/-819 A/T) in patients with pemphigus compared with controls was observed (OR 2.714, 95% CI 1.102-6.685) and this association was also significant when only PV patients were considered (OR 2.667, 95% CI 1.043-6.816). There were no differences between patients and controls in the frequency of any other gene polymorphism analyzed. The increased frequency of the low producer IL-10 haplotype (-1082 /-819 A/T) suggest that the carriage of this haplotype might predispose to pemphigus or the high and intermediate producer haplotypes may be protective factors. The prevalence of the allele IL-10 (-819 T) in pemphigus patients cannot be explained by the current hypothesis, according to which a particular allele of the gene is associated with a different level of cytokine production and therefore affects the predisposition to a particular disease. However, this cytokine polymorphism might be linked to an unknown susceptibility factor.

Cytokine gene polymorphisms in endemic pemphigus foliaceus: a possible role for IL6 variants

Endemic pemphigus foliaceus (EPF) is a complex autoimmune disease characterized by the presence of antibodies against desmoglein 1, which lead to the loss of adhesion among keratinocytes (acantholysis). Variants of HLA class II genes have been the only genetic factors found to modulate susceptibility to EPF. This study aims at investigating the influence of cytokine genetic variants in the pathogenesis of EPF, since they may affect the expression levels of these immunomodulatory molecules. The sample included 168 patients and 189 controls and was comprised of mostly Caucasoids and Mulattos. The approach consisted of a case-control association study and the alleles were identified by mismatched PCR-RFLP. No associations were found with variants of IL1A, IL1B, IL1RN, IL4R and IL10. There was a weak negative association with the haplotype -1082G -592C (OR=0.49) of the IL10 gene in Mulattos. In regard to polymorphism -590 of the IL4 gene, a positive association with the T/T genotype (OR=2.71) and a negative association with the C variant (OR=0.37) were found. Associations with IL6 -174 variants suggest that the C/C genotype has a protective effect (OR=0.13) while carriers of the G allele are more susceptible (OR=7.66) to EPF.

The role of interleukin 10 in the pathogenesis and potential treatment of skin diseases

Interleukin 10 (IL-10) is a key cytokine produced by a multitude of immune effector cells and possesses distinct regulatory effects on immune functioning in the skin. In this article we report the current understanding of the immunobiology of IL-10 and identify the role of IL-10 in cutaneous infection as well as in autoimmune and neoplastic processes. We reviewed the literature to examine the function of IL-10 in different cutaneous disorders. IL-10 can influence and potentially treat T1/T2 differentiation, antigen-presenting cell functioning, antigen-presenting cell-mediated T-cell activation, and T-cell, B-cell, and mast cell growth and differentiation that is aberrant in various disease processes. The literature consensus is that the multitude of effects of IL-10 contribute to the pathogenesis of different skin disorders. In certain circumstances IL-10 could represent novel therapeutic approaches to treating cutaneous diseases.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be acquainted with the role of IL-10 in many infectious diseases, autoimmune skin disease, inflammatory processes, and malignancy. Its possible role in the resolution of various skin diseases should be better understood.

Pemphigus Vulgaris IgG and Methylprednisolone Exhibit Reciprocal Effects on Keratinocytes

Pemphigus vulgaris (PV) is a life-threatening autoimmune disease of skin adhesion associated with IgG autoantibodies against keratinocytes (KC). Treatment of PV with systemic corticosteroids is life-saving, but the mechanism of the therapeutic action has not been fully understood. We have developed an animal model that demonstrates that methylprednisolone (MP) can block PV IgG-induced acantholysis, decreasing the extent of keratinocyte detachment in the epidermis of 3-5-day-old nude mice from 77.5 +/- 0.6 to 24.1 +/- 1.5% (p < 0.05). We hypothesized that in addition to immunosuppression, MP may exhibit direct anti-acantholytic effects in epidermis, and we compared the effects of PV IgG and MP on KC. The use of DNA microarray showed that PV IgG down-regulated and MP up-regulated expression of the genes encoding keratinocyte adhesion molecules, antigen-processing proteins, regulators of cell cycle and apoptosis, differentiation markers, Na+,K+-ATPase, protein kinases and phosphatases, and serine proteases and their inhibitors. Overall, PV IgG decreased transcription of 198 genes and increased transcription of 31 genes. MP decreased transcription of 14 genes and increased transcription of 818 genes. Specific effects of PV IgG and MP on keratinocyte adhesion molecules were further investigated by Western blot and immunofluorescence assays. By immunoblotting, MP increased the protein levels of E-cadherin and desmogleins 1 and 3 by 300, 180, and 40%, respectively. Specific staining of KC for E-cadherin and desmogleins 1 and 3 increased by 235, 228, and 148%, respectively. In addition, PV IgG increased the level of phosphorylation of E-cadherin by 42%, beta-catenin by 37%, gamma-catenin by 136%, and desmoglein 3 by 300%, whereas pretreatment with 0.25 mm MP abolished phosphorylation of these adhesion molecules. These results suggested that therapeutic effects of MP in PV include both the up-regulated synthesis and post-translational modification of the keratinocyte adhesion molecules.

Urokinase plasminogen activator mRNA is induced by IL-1alpha and TNF-alpha in in vitro acantholysis

The role of urokinase type plasminogen activator (uPA) has been well documented in the pathogenesis of pemphigus vulgaris (PV). Activation of plasminogen into active serine protease plasmin initiates extracellular proteolysis leading to acantholysis but the mechanisms underlying this process are not clearly understood. We have previously shown that keratinocyte derived cytokines IL-1alpha and TNF-alpha are involved in PV-induced acantholysis. In the present study we sought to examine whether keratinocyte-derived IL-1alpha and TNF-alpha are correlated with uPA induction in keratinocytes during acantholysis. Normal human keratinocytes were incubated with diluted PV serum. mRNAs for IL-1alpha, TNF-alpha and uPA were examined with RT-PCR at various time points and acantholysis was measured. IL-1alpha, TNF-alpha and uPA mRNAs were all induced in keratinocytes following PV serum stimulation; IL-1alpha/TNF-alpha mRNAs' expression was earlier than the expression of uPA mRNA. To further examine the role of IL-1alpha, TNF-alpha and uPA in acantholysis, we performed antibody blocking studies. Anti-IL-1alpha, anti-TNF-alpha and anti-uPA antibodies suppressed acantholysis by 76%, 80% and 90%, respectively. In addition, anti-IL-1alpha and anti-TNF-alpha antibodies inhibited uPA mRNA induction, whereas anti-uPA antibodies did not alter IL-1alpha/TNF-alpha mRNAs' expression. Our results confirm the role of uPA in acantholysis and suggest an involvement of IL-1alpha/TNF-alpha in uPA induction.

Spreading of epithelial cells on machined and sandblasted titanium surfaces: an in vitro study

BACKGROUND

The purpose of this investigation was to determine the influence of the surface structure of dental implants on epithelial cell spreading and growth in vitro. Cell morphology on machined and sandblasted titanium surfaces was investigated.

METHODS

A total of 10 machined and 10 sandblasted discs and 10 glass coverslips were used for the present study. Samples were analyzed using scanning electron microscopy (SEM) and the cell spreading area was determined using a video image analysis system.

RESULTS

After 24 hours incubation, keratinocytes grown on sandblasted titanium samples displayed numerous, long, and branched or dendritic filopodia closely adapted to the surface roughness. Filopodia varied from 3 to 12 microm in length and 0.1 to 0.3 microm in width. Cells cultured on a machined surface did not present such cytoplasmic extensions and displayed a round morphology. Keratinocytes seeded on glass coverslips were flat and edged by filopodia (maximum length 7 to 8 microm) on the spreading site of the cluster. Though cell morphology is comparable with that observed on sandblasted specimens, cytoplasmic extensions suggestive of strong adhesion and spreading attitude were less pronounced.

CONCLUSION

These results indicate that sandblasted surfaces are the optimal substrata for epithelial cell adhesion and spreading.

Pemphigus vulgaris: update on etiopathogenesis, oral manifestations, and management

Pemphigus is a group of potentially life-threatening diseases characterized by cutaneous and mucosal blistering. There is a fairly strong genetic background to pemphigus with linkage to HLA class II alleles. Certain ethnic groups, such as Ashkenazi Jews and those of Mediterranean origin, are especially liable to pemphigus. Pemphigus vulgaris (PV), the most common and important variant, is an autoimmune blistering disease characterized by circulating pathogenic IgG antibodies against desmoglein 3 (Dsg3), about half the patients also having Dsg1 autoantibodies. Oral lesions are initially vesiculobullous but readily rupture, new bullae developing as the older ones rupture and ulcerate. Biopsy of perilesional tissue, with histological and immunostaining examinations, is essential to the diagnosis. Serum autoantibodies to either Dsg1 or Dsg3 are best detected by both normal human skin and monkey esophagus or by enzyme-linked immunosorbent assay (ELISA). Before the introduction of corticosteroids, pemphigus vulgaris was typically fatal mainly from dehydration or secondary systemic infections. Current treatment is largely based on systemic immunosuppression using systemic corticosteroids, with azathioprine, dapsone, methotrexate, cyclophosphamide, and gold as adjuvants or alternatives, but mycophenolate mofetil and intravenous immunoglobulins also appear promising.

Effect of cordycepin on interleukin-10 production of human peripheral blood mononuclear cells

Therapeutic options for controlling autoimmune diseases are still very limited. Interleukin-10 has been reported to be a promising approach to therapeutic intervention. In the search for a drug which results in the selective upregulation of interleukin-10, we investigated the immunoregulative effects of cordycepin. We have measured interleukin-10 and interleukin-2 secretion of human peripheral blood mononuclear cells that were incubated with cordycepin and assessed the influence of cordycepin on the expression of interleukin-10 mRNA, the proliferative response and the expression of surface markers on T lymphocytes. In addition, the subsets of interleukin-10-secreting cells, the influence of anti-interleukin-10 neutralizing antibody and cytotoxicity of cordycepin were evaluated. Our results suggest that cordycepin has a significantly upregulative effect on interleukin-10 production and interleukin-10 mRNA expression. Interleukin-10-producing cells included in CD4+, CD8+, CD19+, CD56+ and CD14+ cells. At the same time, cordycepin inhibited phytohaemagglutinin-induced interleukin-2 production and proliferation of peripheral blood mononuclear cells. A restricted T lymphocyte activation was also reflected by a reduced expression of the surface markers CD25, CD45RO, CD54, CD71 and HLA DR. Anti-interleukin-10 neutralizing antibody could not completely block the suppressive effect of cordycepin on production of interleukin-2. Cordycepin in the effective concentration presented slight cytotoxicity but did not increase apoptosis. These results indicate that cordycepin exerts immunoregulative effects. Further research on it may provide an approach for the development of novel immunomodulatory drugs which directly alter the secretion of cytokines.

The role of interleukin-10 in autoimmune disease: systemic lupus erythematosus (SLE) and multiple sclerosis (MS)

Interleukin-10 (IL-10) is an immunoregulatory cytokine that plays a crucial role in inflammatory and immune reactions. It has potent anti-inflammatory and immunosuppressive activities on myeloid cell functions which forms a solid basis for its use in acute and chronic inflammatory diseases. Here, we discuss the role of IL-10 in autoimmune diseases and examine its beneficial effects in cellular-based autoimmune diseases such as multiple sclerosis (MS) or its involvement in humoral-based autoimmune diseases such as systemic lupus erythematosus (SLE). Inhibition of the immune stimulatory activities of IL-10 may provide novel approaches in the treatment of humoral autoimmune diseases, infectious diseases and cancer.

Skin-homing interleukin-4 and -13-producing cells contribute to bullous pemphigoid: remission of disease is associated with increased frequency of interleukin-10-producing cells

Although evidence is accumulating that type 2 cytokines play a part in the pathogenesis of bullous pemphigoid, little information is available concerning characterization of the cellular source of these cytokines involved in the pathogenesis of bullous pemphigoid. By using multiparameter flow cytometry, we investigated T cells capable of producing interleukin-2, -4, -10, and -13, interferon-gamma, and tumor necrosis factor-alpha and their correlated expression of skin-homing receptor (cutaneous lymphocyte-associated antigen) in peripheral blood and skin blister of patients with bullous pemphigoid. In peripheral blood of bullous pemphigoid patients, significantly increased frequencies of interleukin-4- and interleukin-13-producing cells were found as compared with those of healthy controls, and the majority of these type 2 cells was found in the cutaneous lymphocyte-associated antigen-positive population. The frequency of interferon-gamma-producing cells was also increased as compared with healthy subjects; however, the majority of this subset was found in the cutaneous lymphocyte-associated antigen-negative population. In the skin blister, the frequencies of interleukin-13- and interleukin-4-producing cells were much higher than those in the peripheral blood of bullous pemphigoid, whereas that of interferon-gamma producing cells was significantly lower. Furthermore, in bullous pemphigoid patients after therapy with systemic corticosteroids, the frequency of cutaneous lymphocyte-associated antigen-positive, but not cutaneous lymphocyte-associated antigen-negative, interleukin-13-producing cells was significantly decreased accompanied by an increased frequency of interleukin-10-producing cells, which was associated with clinical improvement. Thus, our results suggest that bullous pemphigoid is a unique organ-specific autoimmune disease characterized by an expansion of skin-homing interleukin-13-producing cells. In addition, corticosteroids may control such type 2 biased inflammatory responses in bullous pemphigoid by promoting the expansion of interleukin-10-producing cells.

Immunodiagnosis of pemphigus and mucous membrane pemphigoid

Pemphigus and pemphigoid are two of a group of bullous diseases affecting oral mucosa and skin. Mucous membrane pemphigoid (MMP) comprises a heterogeneous group of disorders characterized by subepithelial separation and the deposition of immunoglobulins and complement along the basement membrane zone (BMZ). The target antigens in the epithelium and BMZ determine the nature of the condition, and recently there have been considerable improvements in our understanding of the BMZ antigenic composition. Pemphigus vulgaris (PV) is characterized by autoantibodies of the IgG isotype to the desmosomal glycoprotein desmoglein (Dsg) 3, whereas pemphigus foliaccus targets Dsg1, although at least 50% of PV patients have additional autoantibodies to Dsg1. The clinical phenotype appears to be determined by the relative amounts of Dsg1 and Dsg3. Patients with oral or mucosal PV have predominantly Dsg3 autoantibodies. The most frequently targeted antigen in MMP is bullous pemphigoid antigen 180 (BP180), although bullous pemphigoid antigen 230 (BP230), laminin 5, and beta 4 integrin are also involved. Circulating IgG and IgA antibodies may bind to different epitopes of BP180 namely the NC 16A domain or COOH -terminal domain. Pure ocular disease has been associated with IgA antibodies to a 45-kDa antigen and IgG antibodies to the 205-kDa antigen b4 integrin. The use of salt-split skin substrate enables differentiation between epidermal and dermal 'binders'. Since both the specificity and the antibody titer appear to have direct relationships with the disease severity, and a combination of clinical score and antibody titer provides valuable prognostic data, these investigations should be carried out on a more routine basis.

Further support for a role for Th2-like cytokines in blister formation of pemphigus

Pemphigus vulgaris and pemphigus foliaceus are commonly known as antibody-mediated bullous diseases. However, recently a role for infiltrating cells as contributors to the pathogenesis of these diseases has been suggested. The aims of our study were to characterize the immunophenotype of the cellular infiltrate of pemphigus lesional skin and to study the cytokines secreted. We have therefore performed an immunohistochemical study with a large panel of monoclonal antibodies (to CD3, CD4, CD8, CD25, CD30, myeloperoxidase, eosinophil cationic protein EG2, tryptase, human interleukin (IL)-2, human IL-4, human IL-5, human IL-6, human IL-8, and interferon (IFN)-gamma using the alkaline phosphatase-antialkaline phosphatase procedure on lesional and uninvolved skin of six patients with clinical, histological, and immunofluorescent proven pemphigus. We also performed RT-PCR in order to demonstrate mRNA expression of the cytokines of interest. Our results suggest the presence of a T cell population with a prevalent Th2-like cytokine pattern in lesional skin. In addition, we demonstrate a consistent number of granulocytes and mast cells that show clear signs of activation. These data suggest the involvement of an inflammatory infiltrate in the production of pemphigus lesions. In particular, we assume that Th2 cells may be implicated in the very early stages of autoimmune response, concluding that they exert broad activity in blister formation.

Novel human alpha9 acetylcholine receptor regulating keratinocyte adhesion is targeted by Pemphigus vulgaris autoimmunity

Pemphigus vulgaris (PV) is a potentially fatal autoimmune mucocutaneous blistering disease. It was assumed that PV is caused by anti-desmoglein (Dsg) 3 autoimmunity because absorption of PV sera with a chimeric baculoprotein containing the Dsg 3 and IgG1 portions, rDsg3-Ig-His, eliminated disease-causing antibodies. In this study we demonstrate that rDsg3-Ig-His adsorbs out autoantibodies to different keratinocyte antigens, including a non-Dsg 3 130-kd polypeptide. Because the pool of disease-causing PV IgGs contains antibodies against the keratinocyte acetylcholine receptor (AChR), we sought to identify the targeted receptor(s). Preincubation of monkey esophagus with PV antibodies blocked specific staining of the keratinocyte cell membrane with rabbit monoepitopic antibody to alpha9 AChR, indicating that this first of its kind AChR with dual, muscarinic and nicotinic pharmacology is targeted by PV autoimmunity. Anti-alpha9 antibody stained keratinocytes in a fishnet-like intercellular pattern, and visualized a single band at approximately 50 kd in Western blots of keratinocyte membrane proteins. Using step-by-step reverse transcription polymerase chain reactions with primers based on known alpha9 sequence regions, we identified the complete reading frame of human alpha9. Its amino acid sequence showed 85% similarity with rat alpha9. Treatment of keratinocyte monolayers with anti-alpha9 antibody induced pemphigus-like acantholysis, which could be reversed either spontaneously or by using the cholinergic agonist carbachol. We conclude that alpha9 is coupled to physiological regulation of keratinocyte adhesion, and its interaction with PV IgG may lead to blister development.

Pemphigus vulgaris antibody identifies pemphaxin. A novel keratinocyte annexin-like molecule binding acetylcholine

Because pemphigus vulgaris (PV) IgGs adsorbed on the rDsg3-Ig-His baculoprotein induced blisters in neonatal mice, it was proposed that anti-desmoglein 3 (Dsg 3) autoantibody causes PV. However, we found that rDsg3-Ig-His absorbs autoantibodies to different antigens, including a non-Dsg 3 keratinocyte protein of 130 kDa. This prompted our search for novel targets of PV autoimmunity. The PV IgG eluted from a 75-kDa keratinocyte protein band both stained epidermis in a pemphigus-like pattern and induced acantholysis in keratinocyte monolayers. Screening of a keratinocyte lambdagt11 cDNA library with this antibody identified clones carrying cDNA inserts encoding a novel molecule exhibiting approximately 40% similarity with annexin-2, named pemphaxin (PX). Recombinant PX (rPX-His) was produced in Escherichia coli M15 cells, and, because annexins can act as cholinergic receptors, its conformation was tested in a cholinergic radioligand binding assay. rPX-His specifically bound [(3)H]acetylcholine, suggesting that PX is one of the keratinocyte cholinergic receptors known to be targeted by disease-causing PV antibodies. Preabsorption of PV sera with rPX-His eliminated acantholytic activity, and eluted antibody immunoprecipitated native PX. This antibody alone did not cause skin blisters in vivo, but its addition to the preabsorbed PV IgG fraction restored acantholytic activity, indicating that acantholysis in PV results from synergistic action of antibodies to different keratinocyte self-antigens, including both acetylcholine receptors and desmosomal cadherins.