Frequency analysis of autoreactive T-helper 1 and 2 cells in bullous pemphigoid and pemphigus vulgaris by enzyme-linked immunospot assay

Study of cytokine-induced immunity in bullous pemphigoid: recent developments

Bullous pemphigoid (BP) is an organ-specific disease. Its pathogenesis has not been clearly studied yet; However, studies in recent years have shown that its pathogenesis is related to T helper cells. The pathogenesis of BP is mainly related to Th2 and Th17-related cytokines. IL-4, IL-5 and IL-13 cause eosinophil recruitment, promote antibody production, trigger pruritus and promote blister formation and other symptoms. IL-17 and IL-23 promote the production of matrix metalloproteinase-9 (MMP-9) by related cells, which causes dermo-epidermal junction (DEJ) separation to form bullae and blisters, and can persist in BP inflammation. The serum concentrations of IL-17 and IL-23 are related to the prognosis of BP. In this paper, we focus on the role of related cytokines in the pathogenesis of bullous pemphigoid and the relationship between the related cytokine populations secreted by three major T helper cells-helper T lymphocytes 1 (Th1), Th2, and Th17. A better understanding of the biological and immunological functions of cytokines associated with BP patients will provide opportunities for therapeutic targets in BP.

The emerging role of T cells in pemphigus vulgaris: a systematic review

Pemphigus vulgaris is a potential life-threatening autoimmune bullous disorder. The significant role of autoreactive B cells in the pathogenesis of PV has been explained extensively by producing autoantibodies. Recently, attention has been directed toward the role of T cells in the pathogenesis of PV; in other words, the underlying etiology of PV depends on the interaction between T cells and B cells resulting in antibody secretion. Herein, we systematically review the current literature on the emerging role of T cells in PV. To perform this systematic review, an extensive search through EMBASE, PubMed, Scopus, and ISI databases was performed from 1976 through 2021. Articles investigating the function of T cell subgroups in the pathogenesis or treatment of pemphigus vulgaris were included and reviewed. It is evidenced that T cells play a pivotal role in PV pathogenesis. Th1 and Th2 dichotomy including Th1 suppression and Th2 elevation may induce antibody production against desmoglein in keratinocytes. Furthermore, increased level of Th17 and decreased level of regulatory T cells have been detected in PV patients. However, further studies on the exact role of γδ-T cells in PV are required in order to clarify the pathogenesis of PV. T cells and their subtypes can be involved in the pathogenesis of PV. Thus, they can be considered as tentative targets of novel therapies for PV.

Detection of rare autoreactive T cell subsets in patients with pemphigus vulgaris

Analysis of T lymphocyte proliferation and activation after antigenic or mitogenic stimulation is a vital parameter used in the diagnosis of various immuno-deficiencies and during the monitoring of treatment responses. Most applied techniques are based on the incorporation of tritiated thymidine (³H-TdR) or ELISPOT analysis, both rely on rather time-consuming/-intensive ex vivo protocols or encompass inherent drawbacks such as the inability to distinguish specific cell populations (³H-TdR, ELISPOT) or focus on a single cytokine (ELISPOT). Here we aimed at characterizing the rapid expression of intracellular CD154 (CD40L) as a marker for rare antigen-specific CD4+ T cells in pemphigus vulgaris (PV). Upon stimulation with human desmoglein (Dsg) 3, the major autoantigen in PV, the expression of CD154 was significantly increased in PV patients compared to healthy controls (HC) and correlated with anti-Dsg3 IgG titers. Patients with active disease showed higher numbers of Dsg3-reactive CD4+ T cells in CXCR5+ T follicular helper cells. In remittent PV and HC, CXCR5+CD4+ T cells remained largely unaffected by Dsg3. IL-17 and IL-21 expression were significantly induced only in CD154+CD4+ T cells from PV patients, lending themselves as potential novel treatment targets. Additionally, stimulation with immunodominant Dsg3-derived epitopes strongly induced a CD4+ T cell response via CD40-CD154 interaction similar to the human Dsg3 protein. We here established a rapid ex vivo assay allowing the detection of Dsg3-reactive CD4+ T cells from activated systemically available PBMCs, which further supports the crucial concept of antigen-specific T cells in the pathogenesis of PV.

Autoimmune Pemphigus: Latest Advances and Emerging Therapies

Pemphigus represents a group of rare and severe autoimmune intra-epidermal blistering diseases affecting the skin and mucous membranes. These painful and debilitating diseases are driven by the production of autoantibodies that are mainly directed against the desmosomal adhesion proteins, desmoglein 3 (Dsg3) and desmoglein 1 (Dsg1). The search to define underlying triggers for anti-Dsg-antibody production has revealed genetic, environmental, and possible vaccine-driven factors, but our knowledge of the processes underlying disease initiation and pathology remains incomplete. Recent studies point to an important role of T cells in supporting auto-antibody production; yet the involvement of the myeloid compartment remains unexplored. Clinical management of pemphigus is beginning to move away from broad-spectrum immunosuppression and towards B-cell-targeted therapies, which reduce many patients’ symptoms but can have significant side effects. Here, we review the latest developments in our understanding of the predisposing factors/conditions of pemphigus, the underlying pathogenic mechanisms, and new and emerging therapies to treat these devastating diseases.

Arginase 1+ IL-10+ polymorphonuclear myeloid-derived suppressor cells are elevated in patients with active pemphigus and correlate with an increased Th2/Th1 response

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells, which are characterized by their capability to suppress T-cell responses. While MDSCs have been traditionally associated with cancer diseases, their role as regulators of autoimmune diseases is emerging. Pemphigus is a chronic autoimmune blistering skin disease characterized by dysregulated T-cell responses and autoantibody production. The role of MDSCs in pemphigus disease has not been defined yet. The aim of this study was to characterize MDSCs in pemphigus patients and to dissect their relationship with CD4⁺ T-cell subsets and clinical disease assessments. For this purpose, we performed a cross-sectional analysis of 20 patients with pemphigus. Our results indicate that a population of CD66b⁺ CD11b⁺ polymorphonuclear-like MDSCs (PMN-MDSCs) is expanded in the peripheral blood mononuclear cell fraction of pemphigus patients compared to age-matched healthy donors. These PMN-MDSCs have the capability of suppressing allogeneic T-cell proliferation in vitro and show increased expression of characteristic effector molecules such as arginase I and interleukin-10. We further demonstrate that PMN-MDSCs are especially expanded in patients with active pemphigus, but not in patients in remission. Moreover, MDSC frequencies correlate with an increased Th2/Th1 cell ratio. In conclusion, the identification of a functional PMN-MDSC population suggests a possible role of these cells as regulators of Th cell responses in pemphigus.

Immune serological diagnosis of pemphigus

Pemphigus is a rare autoimmune blistering disease which manifests with painful erosions and blisters of the skin and mucosa. This disorder is caused by autoantibodies attacking desmosomal proteins, necessary for cell-cell contact stability and epidermal integrity. Desmoglein (Dsg) 1 and Dsg3 are the two major target antigens in pemphigus. Yet, many other target proteins, which have been described over the years, seem to be involved in the loss of epidermal integrity. Clinical examination, combined to serological advances and detection of targeted antigens, permitted to differentiate among several pemphigus subtypes, in which pemphigus vulgaris and pemphigus foliaceus are the most common. Nowadays, serological analysis in pemphigus is a fundamental step of the diagnostic algorithm. This is based on analysis of clinical symptoms, histopathological examination of lesional skin, detection of tissue bound and circulating antibodies by direct and indirect immunofluorescence, and determination of target antigens either by enzyme-linked immunosorbent essay (ELISA) or by western blot analysis. A correct and exhaustive diagnostic algorithm is fundamental to characterize pemphigus subtypes, which lastly permits to adopt a correct treatment approach. Moreover, quality and quantity of circulating antibodies in patient's sera deliver important information regarding clinical course, disease severity and treatment response; thus, relevantly affecting physician's decision. To facilitate this process, "easy-to-perform" diagnostic kits with high sensitivity and specificity are being commercialized. In this review, we focus on available methods and established assays to correctly detect circulating autoantibodies in pemphigus. Moreover, we discuss subtype specific serological peculiarities in the five most relevant subtypes (pemphigus vulgaris, pemphigus foliaceus, pemphigus vegetans, paraneoplastic pemphigus and intercellular IgA dermatosis (also called as IgA pemphigus).

Genetic predisposition to bullous pemphigoid

Bullous pemphigoid (BP) is a common autoimmune blistering skin disease that mainly affects elderly patients. Although BP risk is strongly influenced by age, genetic factors are also important determinants of this disease. Many genomic regions, especially in the HLA-II region, have been found to influence BP susceptibility through targeted sequencing studies. However, the relationship between non-HLA regions and BP susceptibility remains poorly understood and the identification of functional variants and key genes within these association regions remains a major challenge. In this review, we summarize the genetic predisposition to BP through an overview of the research history in this field.

Autoreactive T-Lymphocytes in Inflammatory Skin Diseases

The presence of one or several autoantigen(s) and a response by the adaptive immune system are the key criteria to classify a pathology as an autoimmune disease. The list of entities fulfilling this criterion is currently growing in the light of recent advancements in the pathogenetic understanding of a number of important dermatoses. The role of autoreactive T-lymphocytes differs amongst these pathologies. While they are directly involved as effector cells attacking and sometimes killing their respective target in some diseases (e.g., vitiligo), they provide help to B-lymphocytes, which in turn produce the pathogenic autoreactive antibodies in others (pemphigus and pemphigoid). Atopic dermatits is a chimera in this regard, as there is evidence for both functions. Psoriasis is an example for an entity where autoantigens were finally identified, suggesting that at least a subgroup of patients should be classified as suffering from a true autoimmune rather than autoinflammatory condition. Identification of resident memory T-lymphocytes (T_RM) helped to understand why certain diseases relapse at the same site after seemingly effective therapy. Therefore, the in-depth characterization of autoreactive T-lyphocytes goes way beyond an academic exercise and opens the door toward improved therapies yielding durable responses. T_RM are particularly suitable targets in this regard, and the clinical efficacy of some established and emerging therapeutic strategies such as the inhibition of Janus Kinase 3 or interleukin 15 may rely on their capacity to prevent T_RM differentiation and maintenance. Research in this field brings us closer to the ultimate goal in the management of autoimmunity at large, namely resetting the immune system in order to restore the state of tolerance.

T helper type 1 polarizing γδ T cells and Scavenger receptors contribute to the pathogenesis of Pemphigus vulgaris

γδ T cells and Scavenger receptors are key parts of the innate immune machinery, playing significant roles in regulating immune homeostasis at the epithelial surface. The roles of these immune components are not yet characterized for the autoimmune skin disorder Pemphigus vulgaris (PV). Phenotyping and frequency of γδ T cells estimated by flow cytometry have shown increased frequency of γδ T cells (6·7% versus 4·4%) producing interferon- γ (IFN-γ; 35·2% versus 26·68%) in the circulation of patients compared with controls. Dual cytokine-secreting (IFN-γ and interleukin-4) γδ T cells indicate the plasticity of these cells. The γδ T cells of patients with PV have shown higher cytotoxic potential and the higher frequency of γδ T cells producing IFN-γ shows T helper type 1 polarization. The increased expression of Scavenger receptors expression (CD36 and CD163) could be contributing to the elevated inflammatory environment and immune imbalance in this disease. Targeting the inflammatory γδ T cells and Scavenger receptors may pave the way for novel therapeutics.

T cell participation in autoreactivity to NC16a epitopes in bullous pemphigoid

Bullous pemphigoid is a blistering skin disease characterized by autoantibodies against the NC16a domain of bullous pemphigoid 180. This study was performed to characterize and map the fine specificity of T cell responses to NC16a. Peripheral blood mononuclear cells (PBMC) from a total of 28 bullous pemphigoid patients and 14 matched controls were tested for proliferative and cytokine responses to recombinant NC16a and a complete panel of 21 overlapping peptides spanning this region of BP180. Proliferative responses to NC16A and the peptide panel in the patients with active disease were similar in frequency and magnitude to those in healthy donors, and included late responses typical of naive cells in approximately 60% of each group. Interleukin (IL)-4 responses were slightly stronger for six peptides, and significantly stronger for Nc16a, in patients than in controls. Factor analysis identified factors that separate responses to the peptide panel discretely into IL-4, T helper type 2 (Th2) pattern, interferon (IFN)-γ, Th1 pattern and IL-10 or transforming growth factor [TGF-β, regulatory T cell (Treg )] pattern. Factors segregating IL-10 versus IFN-γ were predicted by active blistering or remission, and TGF-β or IL-10 versus IFN-γ by age. Finally, we confirmed a significant up-regulation of IgE responses to BP180 in the patients with pemphigoid. This shows the complexity of T cell phenotype and fine autoreactive specificity in responses to NC16A, in patients and in normal controls. Important disease-associated factors determine the balance of cytokine responses. Of these, specific IL-4 and IgE responses show the strongest associations with pemphigoid, pointing to an important contribution by Th2 cytokines to pathogenesis.

Evidence for pathogenicity of autoreactive T cells in autoimmune bullous diseases shown by animal disease models

Autoimmune bullous diseases (AIBDs) are characterized by blisters and erosions on the skin and/or mucous membranes, which are caused by autoantibodies directed to structural proteins of the epidermis and the epidermal basement membrane zone. This Viewpoint Essay discusses the contribution by autoreactive T cells to the pathogenesis of bullous pemphigoid, pemphigus and epidermolysis bullosa acquisita, with an emphasis on studies using active animal mouse models for these diseases. Previous studies have demonstrated that cytokines produced by autoreactive T cells, the interaction between antigen-specific T cells and B cells and the function of regulatory T cells are likely related to the pathogenesis of AIBDs. In interpreting the experimental results, the limitations of those animal models should be considered. Further understanding of the pathogenicity of autoreactive CD4(+) T cells may lead to disease-specific treatments.

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.

Mechanistic medicine: novel strategies for clinical trials

Autoimmune diseases affect a significant proportion of the population and the development of therapeutics able to manipulate the immune response to deliver effective treatment in these diseases is an accepted approach for drug discovery. This article will focus on recent strategies for achieving selectivity through target choice, thus reducing overall clinical immunosuppression. We review the use of mechanistic pharmacodynamic assays preclinically and in the clinic to assess target engagement and to build the relationship between target coverage and efficacy, to guide dosing. Finally, we review the use of monogenic diseases to deliver proof of mechanism clinical studies and to identify patient populations in larger autoimmune diseases that may be sensitive to intervention with a specific therapeutic.

MAP17 is associated with the T-helper cell cytokine-induced down-regulation of filaggrin transcription in human keratinocytes

In the meta-analysis of public microarray databases for different skin diseases, we revealed seven commonly up-regulated genes, DSG3, KRT6, MAP17, PLSCR1, RPM2, SOD2 and SPRR2B. We postulated that the genes selected from the meta-analysis may be potentially associated with the abnormal keratinocyte differentiation. To demonstrate this postulation, we alternatively evaluated whether the genes of interest in the meta-analysis can be regulated by T-helper (Th) cell cytokines in normal human epidermal keratinocytes (NHEK). We found that MAP17 was significantly up-regulated in response to interferon-gamma, interleukin 4 (IL-4), IL-6, IL-17A or IL-22 in NHEK. Interestingly, MAP17 was originally reported to interact with PDZK1; in turn, the PDZK1 gene is localized within the atopic dermatitis-linked region on human chromosome 1q21. In an attempt to evaluate whether MAP17 regulates the expression of cornified envelope-associated genes at the 1q21 locus, such as filaggrin, loricrin and involucrin, we found that the over-expression of MAP17 in HaCaT keratinocytes significantly decreased the expression of filaggrin. Taken together, the Th cell cytokine-induced up-regulation of MAP17 expression may be linked to the down-regulation of filaggrin in NHEK, which may be associated with the abnormal epidermal differentiation observed in the dermatological diseases.

T and B cells target identical regions of the non-collagenous domain 1 of type VII collagen in epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita (EBA) is a severe immunobullous disease and is caused by IgG against type VII collagen (Col VII) of anchoring fibrils. In this study, utilizing ELISA and immunoblot, 13/15 EBA sera but 0/20 bullous pemphigoid sera and 0/30 healthy control sera showed IgG reactivity with distinct recombinant subregions of the non-collagenous domain 1 (NC1) of Col VII. In two EBA patients, IgG titers against Col VII-NC1 were grossly correlated to clinical disease activity. Moreover, Col VII-reactive T cells were identified in a representative EBA patient which recognized identical subdomains of Col VII-NC1. These findings strongly suggest that (1) the Col VII-NC1 ELISA is a powerful tool for making the diagnosis of EBA, (2) Col VII-specific IgG grossly relates to disease activity and (3) IgG reactivity is associated with T cell recognition of identical subdomains of Col VII-NC1.

Research in practice: Treatment of autoimmune bullous disorders

Autoimmune bullous disorders pose a clinical challenge based on their potentially lethal course and limited therapeutic options. The currently employed immunosuppressive treatments are accompanied by a plethora of side effects. Therefore, our group has sought for many years to dissect the molecular mechanisms of the immune pathogenesis of pemphigus and the pemphigoids allowing for a more specific treatment of these disorders. We have extensively characterized the role of autoaggressive T cells and potential regulatory networks in both disorders and have contributed several tools for more refined serological and T cell-based disease parameters. The ultimate therapeutic goal is anergy induction in these autoaggressive T cells which inititate and perpetuate the B cell-driven immune pathogenesis of pemphigus and the pemphigoids.

Detection of low avidity desmoglein 3-reactive T cells in pemphigus vulgaris using HLA-DR beta 1*0402 tetramers

In the present study, we developed a HLA class II tetramer-based detection system utilizing DRB1*0402 tetramers loaded with recently identified immunodominant peptides of desmoglein 3 (Dsg3), the major autoantigen of pemphigus vulgaris (PV). Initial experiments demonstrated staining of a Dsg3-reactive T cell hybridoma which was derived from HLA-DR0402-transgenic mice with loaded PE-labeled DRbeta1*0402 tetramers. However, staining of autoreactive T cell clones (TCC) derived from PV patients resulted only in positive staining by addition of exogenous peptides to the staining reactions. There was a dose-dependent specific binding of TCC to the tetramers with the agonistic Dsg3 peptide which was not altered by exogenous unrelated Dsg3 peptide. Noteworthy, the TCC did not stain with HLA-DR4 tetramers complexed with unrelated Dsg3 peptides. The findings of this study suggest that HLA class II tetramers may provide a highly specific approach to monitor ex vivo the T cellular autoimmune response against Dsg3 in patients with PV.

T cell control in autoimmune bullous skin disorders

Autoimmune bullous disorders are a group of severe skin diseases characterized clinically by blisters and erosions of skin and/or mucous membranes. A hallmark of these disorders is the presence of IgG and occasionally IgA autoantibodies that target distinct adhesion structures of the epidermis, dermoepidermal basement membrane, and anchoring fibrils of the dermis. This Review focuses on the potential role of autoreactive T cells in the pathogenesis of these disorders. Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are the best-characterized bullous disorders with regard to pathogenesis and T cell involvement. Activation of autoreactive T cells in PV and BP is restricted by distinct HLA class II alleles that are prevalent in individuals with these disorders. Autoreactive T cells are not only present in patients but can also be detected in healthy individuals. Recently, a subset of autoreactive T cells with remarkable regulatory function was identified in healthy individuals and to a much lesser extent in patients with PV, suggesting that the occurrence of autoimmune bullous disorders may be linked to a dysfunction of Tregs.

Cytokine gene polymorphisms in bullous pemphigoid in a Chinese population

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune bullous disease mostly associated with autoantibodies to the hemidesmosomal BP autoantigens BP180 and BP230. High levels of interleukin (IL)-1beta, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma have been detected in skin lesions or sera of patients with BP. Cytokine gene polymorphisms may affect cytokine production and contribute to susceptibility to autoimmune diseases. Until now, no cytokine gene polymorphism study has been conducted on patients with BP.

OBJECTIVES

We aimed to determine whether the genetic polymorphisms of the cytokine genes might influence the development of BP.

METHODS

DNA samples were obtained from 96 BP patients and 174 control subjects. Using direct sequencing and microsatellite genotyping, we examined 23 polymorphisms in 11 cytokine genes including the IL-1alpha, IL-1beta, IL-1 receptor antagonist, IL-4, IL-6, IL-8, IL-10, IL-13, IL-4 receptor, TNF-alpha and IFN-gamma genes.

RESULTS

Although the BP patients were more likely to carry the -511T and -31C alleles of the IL-1beta gene (P = 0.04), the significance disappeared after correction for multiple testing (Pc). There was complete linkage disequilibrium between the -511T and -31C alleles of the IL-1beta gene. In female patients with BP, the associations with IL-1beta (-511T) and (-31C) alleles were much stronger (68% vs. 40.6%, odds ratio = 3.11, Pc = 0.006). No significantly different allelic and genotypic distributions of other cytokine gene polymorphisms could be found between the patients with BP and controls. Moreover, no association with the extent of disease involvement (localized or generalized) was observed.

CONCLUSIONS

The IL-1beta (-511) and (-31) polymorphisms were significantly associated with BP in women. The other genetic polymorphisms of cytokine genes that we analysed do not appear to be associated with BP susceptibility in our Chinese population.

Rapid effector function of circulating NC16A-specific T cells in individuals with mucous membrane pemphigoid

BACKGROUND

Mucous membrane pemphigoid (MMP) is a chronic blistering skin disease frequently associated with circulating autoantibodies directed to a number of antigens including the NC16A region of BP180. NC16A domain-specific T cells have been identified in the blood of individuals with bullous pemphigoid (BP), pemphigoid gestationis and linear IgA disease, but there are no data investigating the potential role for such T cells in the pathogenesis of MMP.

OBJECTIVES

To test the hypothesis that NC16A-specific T cells exist in the peripheral blood of individuals with MMP.

METHODS

We isolated peripheral blood mononuclear cells from 10 patients with MMP, 17 with BP and 10 healthy controls and examined the immunogenicity of overlapping peptides spanning the NC16A domain using interferon (IFN)-gamma enzyme-linked immunospot assay.

RESULTS

Significant IFN-gamma production was observed in response to the NC16A peptides in two of the patients with MMP and two of the patients with BP but in none of the normal controls. These data suggest that in a minority of individuals with MMP, NC16A domain-specific T cells circulate at sufficiently high frequency to be detectable directly ex vivo and to show rapid effector function.

CONCLUSIONS

Overall, these findings are the first to examine the potential role for antigen-specific autoreactive T cells in the pathogenesis of MMP, and confirm that in some individuals the NC16A domain may be an important target antigen.

Interleukin-16 expression and release in bullous pemphigoid

Cutaneous infiltration of activated CD4(+) T cells and eosinophils is an early event in blister formation during bullous pemphigoid (BP), suggesting that the trafficking of circulating leucocytes through the sites of inflammation, their activation and cytokine release is crucial in the pathogenesis of the disease. IL-16 is a major chemotactic factor able to recruit CD4(+) cells in the skin during inflammation and to induce the expression of functional high-affinity interleukin (IL)-2 receptors, thus contributing to cellular activation and proliferation. We performed a study in order to evaluate the presence of IL-16 in skin samples and sera and blister fluids of patients affected with BP in active phase of the disease (n = 39), compared with healthy donors studied as control group. Ten patients were also evaluated before and after steroid therapy. Our results demonstrated that IL-16 was expressed strongly by keratinocytes and by dermal infiltrating CD4(+) T lymphocytes in lesional skin of BP patients. High levels of IL-16 were detected in sera and blisters of BP, significantly higher in respect to healthy donors. When patients were investigated for the presence of eosinophil cationic protein (ECP) and soluble CD30 (sCD30) to reveal signs of eosinophils and Th2-cells activation, we found a positive correlation between IL-16 serum levels and both ECP and sCD30, suggesting that IL-16 is involved in Th2 lymphocytes and eosinophils recruitment during BP.

T-cellular autoimmunity against desmogleins in pemphigus, an autoantibody-mediated bullous disorder of the skin

Pemphigus encompasses a group of life-threatening blistering diseases of the skin in which loss of adhesion between keratinocytes is caused by autoantibodies (Ab) against desmogleins (Dsg) 1 and 3. There is major interest in characterizing autoreactive T cells that are presumably critical for the induction and regulation of Ab production. In a recent study, peripheral Dsg3-reactive T helper (Th) cells from patients with acute onset, chronic active and remittent pemphigus vulgaris (PV) were quantitated by MACS secretion assay. Dsg3-reactive Th2 cells were detected at similar frequencies in all the studied PV patients while the number of autoreactive Th1 cells exceeded those of the Th2 cells in chronic active PV. Noteworthy, healthy carriers of the PV-associated HLA class II alleles, DRbeta1*0402 and DQbeta1*0503, exhibited exclusively Th1 reactivity against Dsg3. The titers of Dsg3-reactive IgG were directly related to the ratio of autoreactive Th1/Th2 cells. Moreover, T cell recognition of Dsg3 was restricted by these HLA class II alleles. These findings strongly suggest that (1) Dsg3-reactive Th2 cells are restricted to PV, (2) distinct HLA class II alleles are critical for T cell recognition of Dsg3, and (3) Ab production is associated with both, Th1 and Th2 cells.

Successful treatment by double-filtration plasmapheresis of a patient with bullous pemphigoid: effects in vivo on transcripts of several genes for chemokines and cytokines in peripheral blood mononuclear cells

The involvement of various cytokines and chemokines has been reported in the pathogenesis of bullous pemphigoid (BP). Double-filtration plasmapheresis (DFPP) is an effective treatment for BP but the mechanism of action remains unclear. Using semiquantitative reverse transcription-polymerase chain reaction, we examined levels of transcripts for various cytokines and chemokines in freshly isolated peripheral blood mononuclear cells in a patient with BP before and after DFPP treatment. DFPP was performed four times. Relative levels of transcripts for interleukin (IL)-8, macrophage inflammatory protein (MIP)-1alpha and IL-5, and the ratio of relative levels of transcripts for IL-4 and interferon (IFN)-gamma, were higher, before treatment, than in healthy controls, and decreased when the extent of the lesions was reduced. Relative levels of transcripts for tumour necrosis factor (TNF)-alpha and IL-4 also decreased with regression of lesions, although they were similar to or lower than the corresponding levels in healthy individuals. When eruptions recurred, relative levels of transcripts for IL-8, MIP-1alpha, RANTES (regulated upon activation normal T cell expressed and secreted), IL-2, IFN-gamma and TNF-alpha were very much higher than those prior to the recurrence, while relative levels of mRNAs for IL-4 and IL-5 did not increase. Relative levels of transcripts for IL-8, MIP-1alpha, TNF-alpha and IL-2 were lower at the end of each individual DFPP and after the four treatments than at the beginning of treatment. Our observations suggest that cytokines and chemokines produced in mononuclear cells play important roles in the pathogenesis of BP and that regulation of their expression might be involved in the therapeutic effects of DFPP in BP.

Dichotomy of autoreactive Th1 and Th2 cell responses to desmoglein 3 in patients with pemphigus vulgaris (PV) and healthy carriers of PV-associated HLA class II alleles

Pemphigus vulgaris (PV) is the most severe autoimmune bullous skin disorder and is primarily associated with circulating autoantibodies (autoAb) against desmoglein 3 (Dsg3). In light of recent evidence that autoreactive T cells are critical for the induction and regulation of Ab production, the goal of this study was to characterize and quantitate autoreactive T cells in patients with PV and healthy controls. Peripheral Dsg3-reactive Th cells from 28 patients with acute-onset, chronic active, and remittent PV were quantitated by MACS secretion assay. Dsg3-reactive Th2 cells were detected at similar frequencies in all studied PV patients, while the number of autoreactive Th1 cells exceeded those of Th2 cells in chronic active PV. In contrast, healthy carriers of the PV-associated HLA class II alleles, DRB1*0402 and DQB1*0503, exhibited exclusively Dsg3-reactive Th1 cell responses, while healthy carriers of other HLA class II alleles did not. Moreover, the presence of IgG1 and IgG4 against Dsg3 was directly related to the ratio of Dsg3-reactive Th1/Th2 cells. T cell recognition of Dsg3 was restricted by HLA-DRB1*0402 and DQB1*0503 in PV patients and Dsg3-responsive healthy donors. These observations strongly suggest 1) that the appearance of Dsg3-reactive Th2 cells is restricted to patients with PV; 2) that specific HLA class II alleles that are prevalent in PV are critical for T cell recognition of Dsg3 in PV patients and Dsg3-responsive healthy donors; and 3) that autoAb production is associated with both Th1 and Th2 cells.

The humanized SCID mouse model to study HLA class II-linked autoimmunity to desmoglein 3 in pemphigus vulgaris

BACKGROUND

Pemphigus vulgaris (PV) is a severe autoimmmune skin disorder induced by antibodies against desmoglein (Dsg) 3 on epidermal keratinocytes.

OBJECTIVES

To establish an active animal model of PV to analyse the T-cell-regulated production of pathogenic antibodies in vivo.

METHODS

Immunodeficient SCID mice were injected with peripheral blood lymphocytes (PBL) from an HLA-DRB1*0402/DQ8+ patient with PV or a DRB1*0402/DQ8+ healthy donor, with or without subsequent injections of human Dsg3 or preincubation of PBL with Dsg3.

RESULTS

Human immunoglobulins (2.7-18.5 mg mL-1) were detected in all the mice after 8 weeks. Only one of 30 PBL-treated mice developed IgM against Dsg3 and showed intercellular IgM deposits in skin, nostrils and tongue. In contrast, in a previous study, 41% of SCID mice injected with PBL from patients with PV developed anti-Dsg3 antibodies in vivo.

CONCLUSIONS

Our inability to reproduce these findings may be due to the transfer of slightly lower numbers of PBL (20 x 10(6) vs. 25-30 x 10(6)).