Search

As the amount of biomedical information available in the literature continues to increase, databases that aggregate this information continue to grow in importance and scope. The population of databases can occur either through fully automated text mining approaches or through manual curation by human subject experts. We here report our experiences in populating the National Institute of Allergy and Infectious Diseases sponsored Immune Epitope Database and Analysis Resource ( IEDB, http://iedb.org), which was created in 2003, and as of 2012 captures the epitope information from approximately 99% of all papers published to date that describe immune epitopes (with the exception of cancer and HIV data). This was achieved using a hybrid model based on automated document categorization and extensive human expert involvement. This task required automated scanning of over 22 million PubMed abstracts followed by classification and curation of over 13 000 references, including over 7000 infectious disease-related manuscripts, over 1000 allergy-related manuscripts, roughly 4000 related to autoimmunity, and 1000 transplant/alloantigen-related manuscripts. The IEDB curation involves an unprecedented level of detail, capturing for each paper the actual experiments performed for each different epitope structure. Key to enabling this process was the extensive use of ontologies to ensure rigorous and consistent data representation as well as interoperability with other bioinformatics resources, including the Protein Data Bank, Chemical Entities of Biological Interest, and the NIAID Bioinformatics Resource Centers. A growing fraction of the IEDB data derives from direct submissions by research groups engaged in epitope discovery, and is being facilitated by the implementation of novel data submission tools. The present explosion of information contained in biological databases demands effective query and display capabilities to optimize the user experience. Accordingly, the development of original ways to query the database, on the basis of ontologically driven hierarchical trees, and display of epitope data in aggregate in a biologically intuitive yet rigorous fashion is now at the forefront of the IEDB efforts. We also highlight advances made in the realm of epitope analysis and predictive tools available in the IEDB. [ABSTRACT FROM AUTHOR]

In this paper we describe the first in vitro response to the liver alloantigen F. The anti-F response serves as a valuable model for autoimmune phenomena since priming appropriate strains of mice (responders) with allogeneic but not syngeneic type F leads to autoantibody production. The in vitro system is based on the proliferation of T cells, from mice primed in vivo with F, when coincubated with splenic adherent cells (SAC) prepulsed with F in vivo. The system displays two important correlates of the in vivo antibody response to F:1.T cells from mice primed with syngeneic F do not proliferate when incubated with SAC prepulsed with syngeneic F and 2. Mice that do not make antibody responses to allo F in vivo (DBA/2) do not show in vitro proliferative responses. These findings indicate that the proliferative assay is a good in vitro model for the F response. [ABSTRACT FROM AUTHOR]

Autoreactive T cells with the phenotype and function of different memory subsets are present in patients who developed type 1 diabetes (TID). According to the progressive differentiation model, memory subsets generate from naïve precursors in a linear and unidirectional path depending on the strength and quality of stimulatory signals. By observing human naïve T cells in contact with GAD65 loaded autologous dendritic cells, we observed that approximately 10% of cells divided with the plane of cell division parallel to the one of the immune synapse, causing phenotypic asymmetries in the proximal and distal daughter T cells. After the first T cell division, proximal and distal daughter T cells showed different phenotype, metabolic signature and commitment to differentiate towards long‐lived memory T cells or T cells with effector function. Subjects with or without T1D showed a similar frequency of asymmetric T cell division (ATCD) for autoantigens and recall antigens specific T cells, however the frequency of ATCD is significantly increased in autoreactive T cells in patients with T1D when IL‐7 was added to the culture. An increased upregulation of GLUT1 in response to IL‐7 in patients with T1D was related to the rate of ATCD. Our results showed that ATCD is associated with an early divergence in the differentiation fate of naïve T cells specific for GAD65 during first antigen encounter. [ABSTRACT FROM AUTHOR]

Introduction: The frequencies and functions of T stem cell memory (TSCM) subsets vary in autoimmune diseases. We evaluated the frequencies of CD4+ and CD8+ TSCM subsets as well as their PD‐1 expression levels in patients with T1D. Methods: Blood samples were collected from new case (NC) (n = 15), and long‐term (LT) (n = 15) groups and healthy controls (n = 15). Five subsets of T cells including TCM(CD4+/CD8+ CCR7+ CD45RO+ CD95+), TCMhi (CD4+/CD8+ CCR7+ CD45ROhi CD95+), TEM(CD4+/CD8+ CCR7− CD45RO+ CD95+), TSCM(CD4+/CD8+ CCR7+ CD45RO− CD95+), and T naive (CD4+/CD8+ CCR7+ CD45RO− CD95−) were detected by flow‐cytometry. Results: The frequency of CD4+ TSCM was higher in NC patients than LT patients and controls (p <.0001 and p =.0086, respectively). A higher percentage of the CD8+ T naive cells was shown in NC patients as compared with LT and healthy individuals (p =.0003 and p =.0002, respectively). An increased level of PD‐1 expression was observed on the CD4+TCM and TCMhi cells in LT patients as compared with healthy controls (p =.0037 and p =.0145, respectively). Also, the higher PD‐1 expression was observed on the CD8+ TCM and TCMhi in NC and LT patients as compared with controls (p =.0068 and p <.0001; p =.0012 and p =.0012, respectively). Conclusion: Considering TSCMs' capacities to generate all memory and effector T cells, our results may suggest a potential association between the increased frequencies of TSCMs and T1D progression. [ABSTRACT FROM AUTHOR]

The pathogenic immune response in celiac disease (CeD) is orchestrated by phenotypically distinct CD4+ T cells that recognize gluten epitopes in the context of disease‐associated HLA‐DQ allotypes. Cells with the same distinct phenotype, but with elusive specificities, are increased across multiple autoimmune conditions. Here, whether sorting of T cells based on their distinct phenotype (Tphe cells) yields gluten‐reactive cells in CeD is tested. The method′s efficiency is benchmarked by parallel isolation of gluten‐reactive T cells (Ttet cells), using HLA‐DQ:gluten peptide tetramers. From gut biopsies of 12 untreated HLA‐DQ2.5+ CeD patients, Ttet+/Tphe+, Ttet−/Tphe+, and Ttet−/Tphe− cells are sorted for single‐cell T‐cell receptor (TCR)‐sequencing (n = 8) and T‐cell clone (TCC)‐generation (n = 5). The generated TCCs are TCR sequenced and tested for their reactivity against deamidated gluten. Gluten‐reactivity is observed in 91.2% of Ttet+/Tphe+ TCCs, 65.3% of Ttet−/Tphe+ TCCs and 0% of Ttet−/Tphe− TCCs. TCR sequencing reveals clonal expansion and sequence sharing across patients, features reflecting antigen‐driven responses. The feasibility to isolate antigen‐specific CD4+ T cells by the sole use of phenotypic markers in CeD outlines a potential avenue for characterizing disease‐driving CD4+ T cells in autoimmune conditions. [ABSTRACT FROM AUTHOR]

Oral lichen planus (OLP) is a T cell–mediated immunoinflammatory disease. Glycolysis plays an essential role in T‐cell immune responses. Blocking glycolytic pathway in activated T cells represents a therapeutic strategy for restraint of immunologic process in autoimmune disorders. 2‐Deoxy‐D‐glucose (2‐DG) has been widely used to probe into glycolysis in immune cells. This study was aimed to explore the role of glycolysis inhibition by 2‐DG on regulating immune responses of OLP‐derived T cells. We observed that lactic dehydrogenase A (LDHA) expression was elevated in OLP lesions and local T cells. 2‐DG inhibited the expression of LDHA, p‐mTOR, Hif1α and PLD2 in T cells; meanwhile, it decreased proliferation and increased apoptosis of T cells. T cells treated by 2‐DG showed lower LDHA expression and elevated apoptosis, resulting in a reduced apoptotic population of keratinocytes that were co‐cultured with them, which was related to the decreased levels of IFN‐γ in co‐culture system. Rapamycin enhanced the effects of 2‐DG on immune responses between T cells and keratinocytes. Thus, these findings indicated that OLP‐derived T cells might be highly dependent upon high glycolysis for proliferation, and 2‐DG treatment combined with rapamycin might be an option to alleviate T‐cell responses, contributing to reducing apoptosis of keratinocytes. [ABSTRACT FROM AUTHOR]

The identification of CD4+ CD25+ Foxp3+ regulatory T (Treg) cells as natural regulators of immunity in the periphery and tissues has stimulated tremendous interest in developing therapeutic strategies for autoimmune diseases. In this review, the site of origin, antigen specificity, homing markers and cytokine profiles of Treg cells were evaluated in autoimmune colitis and type 1 diabetes, two examples in which Treg cells were effective as therapy. These studies were compared with studies of Treg cells in experimental autoimmune encephalomyelitis and multiple sclerosis, where successful therapy has not yet been achieved. Antigen-specific Treg cells appear to have more potent activity than polyclonal Treg cells and therefore hold more promise as therapeutic agents. However, Treg cells specific for the pathogenic T effector cells themselves have largely been overlooked and deserve consideration in future studies. [ABSTRACT FROM AUTHOR]

Regulatory T cells play a key role in immune tolerance to self‐antigens, thereby preventing autoimmune diseases. However, no drugs targeting Treg cells have been approved for clinical trials yet. Here, a chimeric peptide is generated by conjugation of the cytoplasmic domain of CTLA‐4 (ctCTLA‐4) with dNP2 for intracellular delivery, dNP2‐ctCTLA‐4, and evaluated Foxp3 expression during Th0, Th1, Treg, and Th17 differentiation dependent on TGF‐β. The lysine motif of ctCTLA‐4, not tyrosine motif, is required for Foxp3 expression for Treg induction and amelioration of experimental autoimmune encephalomyelitis (EAE). Transcriptome analysis reveals that dNP2‐ctCTLA‐4‐treated T cells express Treg transcriptomic patterns with properties of suppressive functions. In addition, the molecular interaction between the lysine motif of ctCTLA‐4 and PKC‐η is critical for Foxp3 expression. Although both CTLA‐4‐Ig and dNP2‐ctCTLA‐4 treatment in vivo ameliorated EAE progression, only dNP2‐ctCTLA‐4 requires Treg cells for inhibition of disease progression and prevention of relapse. Furthermore, the CTLA‐4 signaling peptide is able to induce human Tregs in vitro and in vivo as well as from peripheral blood mononuclear cells (PBMCs) of multiple sclerosis patients. These results collectively suggest that the chimeric CTLA‐4 signaling peptide can be used for successful induction of regulatory T cells in vivo to control autoimmune diseases, such as multiple sclerosis. [ABSTRACT FROM AUTHOR]

I have briefly reviewed the factors that motivated me to change my views about the existence and importance of suppressor/regulatory T cells and to devote the majority of my laboratory efforts to this newly revitalized area of immunologic research. I am optimistic that manipulation of regulatory T-cell function will shortly be applicable to the clinic. [ABSTRACT FROM AUTHOR]

The pathophysiology of atopic dermatitis (AD) is highly complex and understanding of disease endotypes may improve disease management. Immunoglobulins E (IgE) against human skin epitopes (IgE autoantibodies) are thought to play a role in disease progression and prolongation. These antibodies have been described in patients with severe and chronic AD, suggesting a progression from allergic inflammation to severe autoimmune processes against the skin. This review provides a summary of the current knowledge and gaps on IgE autoreactivity and self‐reactive T cells in children and adults with AD based on a systematic search. Currently, the clinical relevance and the pathomechanism of IgE autoantibodies in AD needs to be further investigated. Additionally, it is unknown whether the presence of IgE autoantibodies in patients with AD is an epiphenomenon or a disease endotype. However, increased knowledge on the clinical relevance and the pathophysiologic role of IgE autoantibodies and self‐reactive T cells in AD can have consequences for diagnosis and treatment. Responses to the current available treatments can be used for better understanding of the pathways and may shed new lights on the treatment options for patients with AD and autoreactivity against skin epitopes. To conclude, IgE autoantibodies and self‐reactive T cells can contribute to the pathophysiology of AD based on the body of evidence in literature. However, many questions remain open. Future studies on autoreactivity in AD should especially focus on the clinical relevance, the contribution to the disease progression and chronicity on cellular level, the onset and therapeutic strategies. [ABSTRACT FROM AUTHOR]

Summary: Immune cell‐mediated destruction of salivary glands is a hallmark feature of Sjögren syndrome. Similar to the female predominance in humans, female non‐obese diabetic (NOD) mice develop spontaneous salivary gland autoimmunity. However, in both humans and mice it is unclear what factors contribute to the initial immune infiltration of the salivary glands. Here, we used an adoptive transfer model of Sjögren syndrome to determine if female mice harbor a sex‐specific defect in salivary‐gland‐protective regulatory T (Treg) cells. Transfer of cervical lymph node (LN) cells from female NOD mice into sex‐matched NOD‐severe combined immunodeficient (SCID) recipients resulted in sialadenitis, regardless of the presence or absence of Treg cells. In contrast, transfer of cervical LN cells from male NOD mice into sex‐matched NOD‐SCID recipients only resulted in sialadenitis when Treg cells were depleted before transfer, suggesting that male NOD mice have functional salivary‐gland‐protective Treg cells. Notably, the host environment affected the ability of Treg cells to prevent sialadenitis with testosterone promoting salivary gland protection. Treg cells from male mice did not protect against sialadenitis in female recipients. Testosterone treatment of female recipients of bulk cervical LN cells decreased sialadenitis, and Treg cells from female mice were capable of protecting against development of sialadenitis in male recipients. Hence, our data demonstrate that female NOD mice develop sialadenitis through a defect in salivary‐gland‐protective Treg cells that can be reversed in the presence of testosterone. [ABSTRACT FROM AUTHOR]

Summary: High salt consumption has since long been associated with elevated blood pressure and cardiovascular disease. Recently, mouse studies suggested that a high dietary salt intake exacerbates the clinical manifestations of autoimmunity. Using naïve cells ex vivo after pre‐exposure of mice to high salt intake, we showed that increased salt exposure affects the viability and effector functions of immune cells. CD4+ T‐cells evidenced a pro‐inflammatory phenotype characterized by increased secretion of IFNγ and IL‐17A, when exposed to high salt concentrations in vitro. Interestingly, this phenotype was associated with osmotic pressure, as replacing salt for d‐mannitol resulted in similar observations. However, high salt intake did not alter the development of T‐cell‐dependent autoimmunity. Instead, recruitment of peritoneal macrophages was increased in mice pre‐exposed to high salt concentrations. These cells had an increased production of both TNFα and IL‐10, suggesting that salt stimulates expansion and differentiation of different subsets of macrophages. Moreover, mice pre‐exposed to high salt intake developed exacerbated symptoms of colitis, when induced by dextran sulphate sodium. The aggravated colitis in salt‐exposed animals was associated with a higher frequency of CD4+ T‐cells and CD11b+ CD64+ macrophages producing TNFα. These phenotypes correlated with elevated titres of faecal IgA and higher lymphocytic cellularity in the colon, mesenteric lymph nodes and spleen. In conclusion, we report here that high salt intake affects both lymphoid and myeloid cells ex vivo. However, the effects of high salt intake in vivo seem less pronounced in terms of CD4+ T‐cell responses, whereas macrophage‐dependent pathologies are significantly influenced. [ABSTRACT FROM AUTHOR]

Summary: Type 1 diabetes (T1D) is a T‐cell‐mediated autoimmune disease resulting in islet β‐cell destruction, hypoinsulinaemia and severely altered glucose homeostasis. Although the mechanisms that initiate T1D still remain elusive, a breakdown of immune tolerance between effector T‐cells (Teff) and regulatory T‐cells (Treg) is considered to be the crucial component leading to autoimmunity. As such, strategies have been developed to boost the number and/or function of Treg in the hope of specifically hampering the pathogenic Teff activity. In this review, we will summarize the current understanding of biomarkers and functions of both forkhead box protein 3 (FoxP3)+ Treg and type 1 regulatory T (Tr1) cells in health and in T1D, examine the outcome of experimental therapies in both animal models and humans via manipulation of Treg responses and also provide an outlook on the potential of Treg‐based immunotherapies in the prevention and treatment of this disease. Discussed immunotherapies include adoptive transfer of ex‐vivo expanded FoxP3+ Treg, manipulation of Treg cells via the interleukin (IL)‐2/IL‐2R pathway and induction of Treg by tolerogenic peptides, tolerogenic dendritic cells or altered gut microbiota. [ABSTRACT FROM AUTHOR]

Cytotoxic T-lymphocyte antigen 4 ( CTLA-4) -mediated regulation of already tolerized autoreactive T cells is critical for understanding autoimmune responses. Although defects in CTLA-4 contribute to abnormal FOXP3+ regulatory T (Treg) cell function in rheumatoid arthritis, its role in autoreactive T cells remains elusive. We studied immunity towards the dominant collagen type II ( CII) T-cell epitope in collagen-induced arthritis both in the heterologous setting and in the autologous setting where CII is mutated at position E266D in mouse cartilage. CTLA-4 regulated all stages of arthritis, including the chronic phase, and affected the priming of autologous but not heterologous CII-reactive T cells. CTLA-4 expression by both conventional T (Tconv) cells and Treg cells was required but while Tconv cell expression was needed to control the priming of naive autoreactive T cells, CTLA-4 on Treg cells prevented the inflammatory tissue attack. This identifies a cell-type-specific time window when CTLA-4-mediated tolerance is most powerful, which has important implications for clinical therapy with immune modulatory drugs. [ABSTRACT FROM AUTHOR]

Two decades ago, we discovered 'superagonistic' monoclonal antibodies specific for the CD28 molecule which are able to polyclonally activate T cells, in particular regulatory T cells, and are therapeutically active in many rodent models of autoimmunity, inflammation, transplantation, and tissue repair. A phase I trial of the human CD28 superagonist TGN1412 failed in 2006 due to an unexpected cytokine release syndrome, but after it became clear that dose-reduction allows to preferentially address regulatory T cells also in humans, clinical development was resumed under the name TAB08. Here, I recount the story of CD28 superagonist development from a personal perspective with an emphasis on the dramatic events during and after the 2006 phase I trial, the reasons for the failure of preclinical research to warn of the impending cytokine storm, and on the research which allowed resumption of clinical development. [ABSTRACT FROM AUTHOR]

Mucosal-associated invariant T ( MAIT) cells are a novel class of innate-like T cells, expressing a semi-invariant T-cell receptor ( TCR) and able to recognize small molecules presented on the non-polymorphic MHC-related protein 1. Their intrinsic effector-memory phenotype, enabling secretion of pro-inflammatory cytokines, and their relative abundance in humans imply a significant potential to contribute to autoimmune processes. However, as MAIT cells were unknown until recently and specific immunological tools were unavailable, little is known of their roles in disease. Here I review observations from clinical studies and animal models of autoimmune and immune-mediated diseases including the roles of MAIT cells in systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease and airways diseases. MAIT cell deficiencies are frequently observed in peripheral blood, and at sites of disease such as the airways in asthma. However, MAIT cells have a specific sensitivity to suppression by therapeutic corticosteroids that may confound many of these observations, as may the tendency of the surface marker CD161 to activation-induced down-regulation. Nonetheless, the dependence on bacteria for the development of MAIT cells suggests a potentially important protective role linking the influences of early life microbial exposures and subsequent development of autoimmunity. Conversely, MAIT cells could contribute to chronic inflammation either through TCR-independent activation, or potentially by TCR recognition of as yet undiscovered ligands. Future research will be greatly facilitated by the immunological tools that are now available, including murine genetic models and human and murine specific tetramers. [ABSTRACT FROM AUTHOR]

The p38 mitogen-activated protein kinase cascade is required for the induction of a T helper type 17 (Th17) -mediated autoimmune response, which underlies the development and progression of several autoimmune diseases, such as experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis (MS). However, the contribution of p38 phosphorylation to human Th cell differentiation has not been clarified. Here we demonstrate that the p38 signalling pathway is implicated in the generation of Th17 lymphocytes from human CD4+ CD27+ CD45RA+ naive T cells, both in healthy donors and in patients affected by the relapsing-remitting form of MS. Our data also indicate that p38 activation is essential for interleukin-17 release from central memory lymphocytes and committed Th17 cell clones. Furthermore, CD4+ T cells isolated from individuals with relapsing-remitting MS display an altered responsiveness of the p38 cascade, resulting in increased p38 phosphorylation upon stimulation. These findings suggest that the p38 signalling pathway, by modulating the Th17 differentiation and response, is involved in the pathogenesis of MS, and open new perspectives for the use of p38 inhibitors in the treatment of Th17-mediated autoimmune diseases. [ABSTRACT FROM AUTHOR]

A role for complement, particularly the classical pathway, in the regulation of immune responses is well documented. Deficiencies in C1q or C4 predispose to autoimmunity, while deficiency in C3 affects the suppression of contact sensitization and generation of oral tolerance. Complement components including C3 have been shown to be required for both B-cell and T-cell priming. The mechanisms whereby complement can mediate these diverse regulatory effects are poorly understood. Our previous work, using the mouse minor histocompatibility (HY) model of skin graft rejection, showed that both C1q and C3 were required for the induction of tolerance following intranasal peptide administration. By comparing tolerance induction in wild-type C57BL/6 and C1q-, C3-, C4- and C5-deficient C57BL/6 female mice, we show here that the classical pathway components including C3 are required for tolerance induction, whereas C5 plays no role. C3-deficient mice failed to generate a functional regulatory T (Treg) -dendritic cell (DC) tolerogenic loop required for tolerance induction. This was related to the inability of C3-deficient DC to up-regulate the arginine-consuming enzyme, inducible nitric oxide synthase ( Nos-2), in the presence of antigen-specific Treg cells and peptide, leading to reduced Treg cell generation. Our findings demonstrate that the classical pathway and C3 play a critical role in the peptide-mediated induction of tolerance to HY by modulating DC function. [ABSTRACT FROM AUTHOR]

Quantitative reductions in T-cell receptor ( TCR) signalling are associated with severe immunodeficiency, yet in certain cases can lead to autoimmunity. Mutation of the tyrosine kinase ZAP-70 can cause either of these outcomes, yet the limits of its signal transducing capacity are not well defined. To investigate these limits we have made use of mrtless: a chemically induced mutation of Zap70 associated with T-cell deficiency. Unlike cells devoid of ZAP-70, mrtless thymocytes showed partial induction of CD5 and CD69, and were sensitive to TCR stimulation with a dose-response shifted approximately 10-fold. However, essentially no T cells were able to compensate for the mrtless mutation and mature beyond the CD4+ CD8+ stage. This outcome contrasts with a ZAP-70 Src Homology 2 domain mutant strain, where high-affinity self-reactive TCR are positively selected rather than deleted. We discuss these data with respect to current models of TCR signalling in thymocyte selection. [ABSTRACT FROM AUTHOR]

Invariant NKT (iNKT) cells are a distinctive subtype of CD1d-restricted T cells involved in regulating autoimmunity and capable of producing various T helper type 1 (Th1), Th2 and Th17 cytokines. Activation of iNKT cells by their exogenous ligand α-galactosylceramide (α-GalCer) exerts therapeutic effects in autoimmune diseases such as rheumatoid arthritis (RA). However, the pathophysiological role of iNKT cells in RA, in the absence of exogenous stimulation, is incompletely understood. We investigated the potential pathophysiological effects of iNKT cells in mice with collagen-induced arthritis (CIA), a model of RA. We found that iNKT cells underwent activation only in the early phases of the disease (6 days post-induction). In the liver, but not the spleen or lymph nodes, this early activation led to the release of interleukins -4, -17A and -10 and of interferon-γ; and an increased CD69 expression. Importantly, clinical and histological signs of arthritis were improved by the functional blockade of iNKT cells by a monoclonal antibody to CD1d at the early phase of the disease. This improvement was associated on day 6 post-induction with decreased expression of co-stimulatory molecules (CD80, CD86, CD40) on splenic dendritic cells and macrophages, whereas regulatory T-cell suppressive effects and proportions were not modified. Taken in concert, these findings suggest that iNKT cells are activated early in the course of CIA and contribute to the pathogenesis of arthritis. Therefore, iNKT-cell activation may be a valid treatment target in RA. [ABSTRACT FROM AUTHOR]

Pemphigus vulgaris (PV) is an autoimmune bullous skin disorder associated with autoantibodies against desmoglein (Dsg) 3. An imbalance of type 1 regulatory T (Tr1) cells and T helper type 2 (Th2) cells specific for Dsg3 may be critical for the loss of tolerance against Dsg3 in PV. Within the population of Dsg3-responsive, interleukin (IL)-10-secreting Tr1 cell clones, two major subpopulations were identified and sorted by fluorescence-activated cell sorting (FACS) based on their size and granularity. Upon in vitro culture, the larger subpopulation differentiated back into the two former subpopulations of the Tr1 cell clones, while the smaller subpopulation died within 2 weeks. The smaller subpopulation of the Tr1 cell clones was characterized by the expression of Foxp3, the secretion of IL-10, transforming growth factor (TGF)-β and IL-5 upon stimulation with Dsg3, a proliferative response to IL-2 but not to Dsg3 or mitogenic stimuli, and an inhibitory effect on the proliferative response of Dsg3-responsive Th clones in a Dsg3-specific manner. In contrast, the larger subpopulation showed a Th-like phenotype, lacking Foxp3, cytotoxic T-lymphocyte antigen 4 (CTLA4) and glucocorticoid-induced tumour necrosis factor receptor (GITR) expression and IL-2 secretion, and did not mount a proliferative response to Dsg3 and mitogenic stimuli. The two Tr1 subpopulations showed expression of identical T-cell receptor (TCR) Vβ chains which varied among the PV patients studied. Upon inhibition of Foxp3, the smaller Tr1 subpopulation developed a proliferate response to Dsg3 and mitogenic stimuli, no longer suppressed Dsg3-specific Th cells, lost expression of GITR and CTLA4 and secreted IL-2. Thus, our observations suggest a distinct relationship between Dsg3-specific Tr1 and Th-like cells which may be critical for the continuous generation and survival of Dsg3-specific Tr1 cells. [ABSTRACT FROM AUTHOR]

The healthy host does not normally develop tissue destructive autoimmunity in part because of the presence of natural regulatory T cells. These cells are best identified by their expression of a unique transcription factor forkhead box transcription factor (Foxp3) that controls their regulatory function. Several other types of regulatory T cells also occur most of which are induced in response to antigen stimulation. Some of these express the Foxp3 transcription factor but many do not. The role of natural T-regulatory cells as well as induceable regulatory cells in autoimmunity, cancer, allergy and infectious disease is described. The current status of therapeutic approaches that modulate regulatory T-cell responses on the outcome of experimental animal and human disease is also discussed. [ABSTRACT FROM AUTHOR]

C1q deficiency has been shown to accelerate spontaneous autoimmunity in mice. We studied the time course of activation of monocytes and lymphocytes in autoimmune and non-autoimmune mice in the presence or absence of C1q as a disease accelerator. Autoimmune MRL\Mp. C1qa −\− and non-autoimmune C57BL\6. C1qa −\− mice were analysed at various time points between 6 and 33 weeks of age and compared to strain- and age-matched C1q-sufficient controls. Splenic and peritoneal leucocytes were analysed by flow cytometry and plasma levels of immunoglobulin M (IgM), total IgG, IgG subclasses and IgM autoantibodies were measured. Both C1q-deficient strains had significantly more splenic monocytes than their controls at all time points analysed. In addition, MRL\Mp. C1qa −\− but not C57BL/6. C1qa −\− mice developed splenic hypercellularity starting at about 12–17 weeks old, had signs of accelerated CD4+ T-cell activation and showed a marked increase in splenic plasma cells and total serum IgM levels from about 22 weeks of age. The accelerated CD4+ T-cell activation was not due to a direct inhibitory effect of C1q on T cells. These data show that C1q deficiency causes splenic monocytosis together with accelerated T-cell activation in an autoimmune-prone mouse strain. [ABSTRACT FROM AUTHOR]

Recently, we have described a soluble survival signal for activated lymphocytes from CD14+ cells. As a result of the importance of T lymphocytes in the pathogenesis of rheumatoid arthritis (RA), we speculate a possible role for CD14+ cells in supporting the outgrowth of autoreactive lymphocytes in RA. To address this issue further, supernatants from activated CD14+ cells (CD14 cocktails) in both normal controls and RA patients were collected. The relative strength of the CD14 cocktails from normal controls and RA patients was compared. The data showed that depletion of CD14+ calls resulted in a much higher increase of activation-induced cell death (AICD) and a decrease of lymphocyte proliferation in the peripheral blood mononuclear cells of RA patients compared to normal controls. Interestingly, CD14 cocktails from RA patients provide much stronger protection against AICD compared to those from normal controls. The observed soluble survival signal from CD14+ cells is a general phenomenon because CD14 cocktails prevent both phytohaemagglutinin A-p- and anti-CD3-induced AICD. Furthermore, supernatants collected from human dendritic cell cultures also prevent activated lymphocytes from undergoing AICD. The data implicate an important role of the CD14+ cell and its secreted form of survival signal in the pathogenesis of RA. [ABSTRACT FROM AUTHOR]

Autoreactive IL-2-producing T-cell hybridomas were established from New Zealand Black and White (B/W) F1 and MRL/1 mice. In B/WF1 mice the the frequency of IL-2-producing hybridomas increased with age. It is necessary for the cells to recognize autologous MHC molecules in order to release IL-2. Inoculation of hybridoma cells into several mouse strains via the footpad produced significant swelling responses in an H-2-restricted manner. Finally, several autoimmune abnormalities were induced in naive H-2-compatible mice by i.v. inoculation of certain hybridoma cells. These results demonstrate that self-MHC molecule recognition by T cells plays an important role in the development of autoimmunity. [ABSTRACT FROM AUTHOR]

Splenic B cells from older MRL/ Mp-lpr/lpr (MRL/1) and male BXSB mice responded to 2-mercaptoethanol (2-ME) in in vitro culture and generated immunoglobulin-secreting cells (IgSC). Optimal concentration of 2-ME to induce IgSC was 5 x 10-5 M. Kinetic studies revealed that the generation of IgSC was already apparent after 24 hr of culture and peak response was attained on the 2nd day. The response of B cells to 2-ME was enhanced in the presence of splenic T cells. Irradiation of B cells reduced the generation of IgSC. The B cell population of autoimmune mice responding to 2-ME to generate IgSC seems to be in a terminal stage of differentiation. This increased B cell differentiation was characteristic of autoimmune mice and assumed to have some significance in the development of autoimmune diseases. [ABSTRACT FROM AUTHOR]

When SJL mice are hyperimmunized with rat red blood cells (RBC), tolerance to self is readily broken and these animals develop a high autoantibody response to their own RBC. However, these mice also fail to generate those antigen-specific suppressor cells which normally regulate this induced autoantibody response. [ABSTRACT FROM AUTHOR]

Inducibility of immunological tolerance to a T-dependent antigen, human serum albumin, was studied in autoimmune mice (NZB, MRL/Mp-1pr/1pr and male BXSB mice), comparing with non-autoimmune mice (BALB/c, DBA/2, MRL/Mp- +/+ and female BXSB mice). Weekly injections of increasing doses of the tolerogen into DBA/2 mice induced T-cell tolerance without the participation of suppressor cells and without affecting B cells. All of the autoimmune mice tested were refractory to the tolerogen; partial tolerance (40%-60% responsiveness) was attained in mice aged 1 month, but not in older mice. By comparison, tolerance was induced in non-autoimmune mice to a similar degree irrespective of the age of the mice. The tolerance inducibility was also examined in reciprocal bone marrow cell (BMC) transfer experiments between NZB and DBA/2 mice and also BMC transfer into B10.D2 mice. It was shown that recipients of NZB BMC were more resistant to tolerance induction than those of DBA/2 BMC, while irradiated NZB mice receiving DBA/2 BMC were susceptible. Hence, it is suggested that the tolerance-resistant nature of the NZB mice was inherent in T-cell precursors in the bone marrow and not in the host environment. Similar findings in support of this notion were also observed in BSXB mice. The significance of tolerance resistance in the development of autoimmunity is discussed. [ABSTRACT FROM AUTHOR]

The ability to induce autoantibodies to erythrocytes in male and female (NZB × NZW)F1 mice was examined. Female (NZB × NZW)F1 mice were shown to produce significantly more autoantibody than the male (NZB × NZW)F1 mice. The regulation of this experimentally induced autoantibody was studied by examining the ability of male and female (NZB × NZW)F1 mice to generate antigen- specific suppressor cells. A sex difference was found in the ability to generate these suppressor cells. Male mice generated antigen-specific suppressor cells in response to rat RBC which were capable of suppressing the experimental induction of red cell autoantibodies whereas female mice were unable to generate these antigen-specific suppressor cells. [ABSTRACT FROM AUTHOR]

Suppressor cells in the spleens of overtly autoimmune NZB &xtimes; NZW (B/W) mice, but not age matched normal strain mice, were shown to release a small, <20,000 Dalton factor which inhibited early events in the anti-SRBC PFC response and the mitogenic response. This splenic inhibitory factor (SIF) was (i) stable on heating (56°, 30 min) and freezing (-70°); (ii) non-specific for antigen; (iii) absorbed and/or inactivated by target cells in young B/W spleen cell cultures and (iv) released gradually into the culture medium by metabolically active cells. SIF also blocked the T-cell replacing effect of allogeneic factors (TRF) in the anti-SRBC response. These observations suggest that SIF may lead to the immunodepressed state in overtly autoimmune B/W mice by preventing the activation or differentiation of lymphocytes responding to exogenous antigen. [ABSTRACT FROM AUTHOR]

Interferon-γ (IFN-γ) is an important cytokine which regulates inflammatory and immune response mechanisms. IFN-γ enhances the presentation and recognition of antigens by inducing the expression of major histocompatibility complex (MHC) proteins, by activating effector T cells and mononuclear phagocytes, and by modulating immunoglobulin production and class selection in B cells. Inappropriate production of IFN-γ has been implicated in the pathogenesis of several autoimmune and inflammatory diseases and in graft rejection. Here, we describe, a recombinant inhibitor of IFN-γ, termed murine IFN-γ receptor immunoadhesin (mIFN-γR-IgG). We constructed this immunoadhesin by linking the extracellular portion of the mouse IFN-γR to the hinge and Fc region of an IgG1 heavy chain. Murine IFN-γR-IgG is secreted by transfected cells as a disulphide-bonded homodimer which binds IFN-γ bivalently, with high affinity and in a species-specific manner. In vitro, mIFN-γRIgG can block mIFN-γ-induced antiviral activity and expression of the class I MHC antigen H-2Kk in cultured cells. In vivo, mIFN-γ,R-IgG can block the function of endogenous mIFN-γ in mouse models of infection with Listeria monocytogenes and of contact sensitivity. These results show that mIFNγR-IgG is an effective and specific inhibitor of mIFN-γ both in vitro and in vivo. Thus, in general, IFN-γ receptor immunoadhesins may be useful for investigating the biological functions of IFN-γ as well as for preventing deleterious effects of IFN-γ in human disease. [ABSTRACT FROM AUTHOR]

NOD‐like receptor (NLR) family CARD domain containing 3 (NLRC3), an intracellular member of NLR family, is a negative regulator of inflammatory signaling pathways in innate and adaptive immune cells. Previous reports have shown that NLRC3 is expressed in dendritic cells (DCs). However, the role of NLRC3 in DC activation and immunogenicity is unclear. In the present study, we find that NLRC3 attenuates the antigen‐presenting function of DCs and their ability to activate and polarize CD4+ T cells into Th1 and Th17 subsets. Loss of NLRC3 promotes pathogenic Th1 and Th17 responses and enhanced experimental autoimmune encephalomyelitis (EAE) development. NLRC3 negatively regulates the antigen‐presenting function of DCs via p38 signaling pathway. Vaccination with NLRC3‐overexpressed DCs reduces EAE progression. Our findings support that NLRC3 serves as a potential target for treating adaptive immune responses driving multiple sclerosis and other autoimmune disorders. Synopsis: The innate immune sensor NLRC3 negatively regulates dendritic cell activation to affect Th1 and Th17 cell differentiation and experimental autoimmune encephalomyelitis. NLRC3 attenuates the antigen‐presenting function of DCs and their ability to activate and polarize CD4+ T cells into Th1 and Th17 subsets.Loss of NLRC3 promotes pathogenic Th1 and Th17 responses and enhanced EAE development.NLRC3 negatively regulates the antigen‐presenting function of DCs via p38 signaling pathway. [ABSTRACT FROM AUTHOR]