Autoreactive T Cells Research Articles

Mechanisms of Inflammation in Neutrophil-Mediated Skin Diseases.

Neutrophil-mediated skin diseases, originally named neutrophilic dermatoses (NDs), are a group of conditions due to an altered neutrophil recruitment and activation, characterized by polymorphic cutaneous manifestations with possible internal organ involvement. Although a number of diseases are included in this setting, the two prototypic forms are pyoderma gangrenosum (PG) and Sweet's syndrome (SS) which usually present with skin ulcers and plaque-type lesions, respectively. They have central features significantly overlapping with autoinflammatory conditions which manifest as repeated episodes of tissue inflammation. However, in contrast to appropriate inflammatory responses to insults or to autoimmune disease, there is an absence of identifiable pathogens, autoantibodies, or autoreactive lymphocytes. The recognition of monogenic autoinflammatory diseases which can present with NDs has led to study several genes involved in autoinflammation in NDs. Based on discovering of a number of mutations involving different autoinflammatory genes, neutrophil-mediated skin diseases are nowadays regarded as a spectrum of polygenic autoinflammatory conditions. Although disease mechanisms have not yet been completely elucidated, NDs are recognized as diseases involving dysfunctional cellular signaling mediated by pathways mainly related to inflammasome and IL-1 with the contributory role of IL-17 and other effector molecules. The precise elucidation of the above-mentioned pathologic mechanisms may pave the way to tailored treatments for patients with different neutrophil-mediated skin diseases.

SINGLE-TARGET PAN-LIVER AUTOIMMUNE DISEASE-SUPPRESSING NANOMEDICINES

Abstract Peptide-major histocompatibility complex class II (pMHCII)-based nanomedicines displaying tissue-specific autoantigenic epitopes can blunt specific autoimmune conditions by re-programming cognate antigen-experienced CD4+ T-cells into disease-suppressing T-regulatory type 1 cells. Here, we show that single pMHCII-based nanomedicines displaying epitopes from primary biliary cholangitis (PBC)- or autoimmune hepatitis (AIH)- relevant mitochondrial, endoplasmic reticulum or cytoplasmic antigens can broadly blunt PBC, AIH and Primary Sclerosing Cholangitis in various murine models in a non-disease-specific manner without suppressing general or local immunity against infection or metastatic allogeneic tumors. Thus, CD4+ T-cell autoreactivity against liver-enriched autoantigens in liver autoimmune inflammation is not disease-specific and can be harnessed to treat various liver autoimmune diseases broadly.

A Public BCR Present in a Unique Dual-Receptor-Expressing Lymphocyte from Type 1 Diabetes Patients Encodes a Potent T Cell Autoantigen

T and B cells are the two known lineages of adaptive immune cells. Here, we describe a previously unknown lymphocyte that is a dual expresser (DE) of TCR and BCR and key lineage markers of both B and Tcells. In type 1 diabetes (T1D), DEs are predominated by one clonotype that encodes a potent CD4 Tcell autoantigen in its antigen binding site. Molecular dynamics simulations revealed that this peptide has an optimal binding register for diabetogenic HLA-DQ8. In concordance, a synthetic version of the peptide forms stable DQ8 complexes and potently stimulates autoreactive CD4 Tcells from T1D patients, but not healthy controls. Moreover, mAbs bearing this clonotype are autoreactive against CD4 Tcells and inhibit insulin tetramer binding to CD4 Tcells. Thus, compartmentalization of adaptive immune cells into T and B cells is not absolute, and violators of this paradigm are likely key drivers of autoimmune diseases.

Interrogating Individual Autoreactive Germinal Centers by Photoactivation in a Mixed Chimeric Model of Autoimmunity.

Autoimmune diseases present a significant health burden. Fundamental questions regarding the development and progression of autoimmune disease remain unanswered. One requirement for advancements in our understanding of the underlying disease mechanisms and cellular dynamics is the precise coupling of the microanatomical location of cell subsets with downstream molecular or functional analyses; a goal that has traditionally been difficult to achieve. The development of stable photoactivatable biological fluorophores and their integration into reporter strains has recently enabled precise microanatomical labeling and tracking of cellular subsets in murine models. Here, we describe how the ability to analyze autoreactive lymphocytes from single germinal centers may help to provide novel insights into autoimmunity, using the combination of a novel chimeric model of autoimmunity with a photoactivatable reporter as an example. We demonstrate a procedure for generating mixed chimeras with spontaneous autoreactive germinal centers populated by lymphocytes carrying a photoactivatable green fluorescent protein reporter. Using in vivo labeling strategies, single germinal centers can be visualized in explanted lymphoid tissues and their cellular constituents photoactivated by two-photon microscopy. Photoactivated lymphocytes from single germinal centers can then be analyzed or sorted flow cytometrically, as single cells or in bulk, and may be subjected to additional downstream molecular and functional analyses. This approach may directly be applied to provide renewed insights in the field of autoimmunity, but the procedure for generating bone marrow chimeras and the photoactivation procedure may additionally find broad application in studies of infectious diseases and tumor metastases.

Immunological Mechanisms of Autoimmune Thyroid Diseases: A Shift in The Traditional TH1/TH2 Paradigm

Abstract Autoimmune thyroid diseases (AITD) mainly include Hashimoto’s thyroiditis (HT) and Graves’ disease (GD), which are characterised by the presence of circulating antibodies against various thyroid autoantigens and infiltration of the thyroid gland by autoreactive lymphocytes. Despite the significant advancement in the knowledge of AITD pathogenesis in the last decade, the specific immunological mechanisms responsible for development of the disease are not thoroughly understood. Classically, HT has long been considered as a T helper (Th)1-mediated disease, while a Th2-driven autoimmune response is dominant for GD development. However, this classification has changed due to the description of Th17 lymphocytes, which suggested participation of these cells in AITD, particularly HT pathogenesis. Moreover, a shift in the balance between Th17 and T regulatory (Treg) cells has been observed in thyroid autoimmunity. We have observed overexpression of IL-17, the prominent effector cytokine of Th17, within thyroid tissues from HT and GD patients in our studies. The present review will focus on recent data regarding the role of Treg and Th17 lymphocytes in AITD pathogenesis. In addition, the impact and proposed mechanisms of the predominant environmental factors triggering the autoimmune response to the thyroid will be discussed.

Genetic Restoration of Heme Oxygenase-1 Expression Protects from Type 1 Diabetes in NOD Mice.

Antigen-presenting cells (APCs) including dendritic cells (DCs) play a critical role in the development of autoimmune diseases by presenting self-antigen to T-cells. Different signals modulate the ability of APCs to activate or tolerize autoreactive T-cells. Since the expression of heme oxygenase-1 (HO-1) by APCs has been associated with the tolerization of autoreactive T-cells, we hypothesized that HO-1 expression might be altered in APCs from autoimmune-prone non-obese diabetic (NOD) mice. We found that, compared to control mice, NOD mice exhibited a lower percentage of HO-1-expressing cells among the splenic DCs, suggesting an impairment of their tolerogenic functions. To investigate whether restored expression of HO-1 in APCs could alter the development of diabetes in NOD mice, we generated a transgenic mouse strain in which HO-1 expression can be specifically induced in DCs using a tetracycline-controlled transcriptional activation system. Mice in which HO-1 expression was induced in DCs exhibited a lower Type 1 Diabetes (T1D) incidence and a reduced insulitis compared to non-induced mice. Upregulation of HO-1 in DCs also prevented further increase of glycemia in recently diabetic NOD mice. Altogether, our data demonstrated the potential of induction of HO-1 expression in DCs as a preventative treatment, and potential as a curative approach for T1D.

The role of stroma and epithelial cells in primary Sjögren's syndrome.

Primary SS (pSS) is a chronic autoimmune condition characterized by infiltration of the exocrine glands and systemic B cell hyperactivation. This glandular infiltration is associated with loss of glandular function, with pSS patients primarily presenting with severe dryness of the eyes and mouth. Within the affected glands, the infiltrating lymphocytes are organized in tertiary lymphoid structures. Tertiary lymphoid structures subvert normal tissue architecture and impact on organ function, by promoting the activation and maintenance of autoreactive lymphocytes. This review summarizes the current knowledge about the role of stromal cells (including endothelium, epithelium, nerves and fibroblasts) in the pathogenesis of pSS, in particular the interactions taking place between stromal cells and infiltrating lymphocytes. We will provide evidences pointing towards the driving role of stromal cells in the orchestration of the local inflammatory milieu, thus highlighting the need for therapies aimed at targeting this compartment alongside classical immunosuppression in pSS.

Research progress of peripheral blood regulatory T cell/helper T cell 17 imbalance and relevant gene methylation in immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease. The classic pathogenesis of ITP is that the production of autoantibodies against platelet membrane glycoproteins, which mediates platelet destruction. In recent years, it has been found that there are still many other mechanisms in ITP inducing thrombocytopenia and platelet damage, among which abnormal cellular immunity plays an important role. In cellular immunity, CD4+ CD25high CD127- regulatory T cells (Treg) are a group of T cell subsets that exist in human peripheral blood and spleen and can inhibit auto-reactive T cell responses; T helper cells (Th)17 is a newly discovered T cell subset that secretes interleukin (IL)-17, involved in mediating inflammatory response, which is of great significance in autoimmune diseases. Several studies showed that Treg/Th17 imbalance and abnormal expression of specific transcription factors folkhead box protein (Foxp)3 and retinoic acid-related orphan nuclear receptor (ROR)-γt were observed in peripheral blood of ITP patients. DNA methylation induces Foxp3 gene silencing and abnormal activation of IL-6/STAT3 signaling pathway, which may be the mechanism leading to Treg/Th17 imbalance and causes of ITP. The proposed demethylation treatment may provide new ideas for the molecular targeted treatment of ITP, but its scientificity, effectiveness and safety still need to be confirmed by further studies. The author reviews literature on the role of Treg/Th17 imbalance and relevant gene methylation mechanism in the occurrence, development and treatment of ITP. Key words: T-lymphocytes, regulatory; T-lymphocyte subsets; DNA methylation; Thrombocytopenia; Helper T lymphocyte 17; Decitabine

Autoimmunity and immunological tolerance in autoimmune bullous diseases.

Autoimmune diseases are devastating conditions in which the immune system is directed against the host, leading to life-threatening destruction of organs. Although autoantigens are ill-defined in most autoimmune diseases, this is not the case in the skin. Autoimmune bullous diseases have been extensively studied with detailed characterization of autoantigens, the epitopes that are targeted, and the mechanisms of action that mediate autoimmune tissue destruction. Pemphigus is an autoimmune bullous disease caused by circulating IgG that targets two desmosomal proteins, desmoglein 1 and 3, which are crucial for cell-cell adhesion of keratinocytes. Binding of auto-antibodies to desmogleins impairs keratinocyte adhesion, leading to severe blistering disease. Mouse models that recapitulate the human disease have been instrumental in elucidating the detailed pathophysiology. Taking advantage of the fact that desmogleins are specifically targeted in pemphigus, studying humoral and cellular autoimmunity against these autoantigens provides us with an opportunity to understand not only the effector mechanisms of B and T cells in mediating pathology but also how autoreactive lymphocytes are regulated during development in the thymus and post-development in the periphery. This review introduces pemphigus and its subtypes as prototypic autoimmune diseases from which recent basic and translational developments should provide insight into how autoimmunity develops.

Depletion of PD-1-positive cells ameliorates autoimmune disease.

Targeted suppression of autoimmune diseases without collateral suppression of normal immunity remains an elusive yet clinically important goal. Targeted blockade of the programmed death-1 receptor (PD-1) — an immune checkpoint factor expressed by activated T cells and B cells — is an efficacious therapy for potentiating immune activation against tumours. Here, we show that an immunotoxin consisting of an anti-PD-1 single-chain variable fragment, an albumin-binding domain and Pseudomonas exotoxin targeting PD-1-expressing cells selectively recognizes and induces the killing of the cells. Administration of the immunotoxin to mouse models of autoimmune diabetes delays disease onset, and its administration in mice paralyzed by experimental autoimmune encephalomyelitis ameliorates symptoms. In all mouse models, the immunotoxin reduced the numbers of PD-1-expressing cells, of total T cells and of cells of an autoreactive T cell clone found in inflamed organs, while maintaining active adaptive immunity, as evidenced by full-strength immune responses to vaccinations. The targeted depletion of PD-1-expressing cells contingent to the preservation of adaptive immunity might be effective in the treatment of a wide range of autoimmune diseases.

A mathematical solution to Peto\u2019s paradox using Polya\u2019s urn model: implications for the aetiology of cancer in general

Ageing is the leading risk factor for the emergence of cancer in humans. Accumulation of pro-carcinogenic events throughout life is believed to explain this observation; however, the lack of direct correlation between the number of cells in an organism and cancer incidence, known as Peto’s Paradox, is at odds with this assumption. Finding the events responsible for this discrepancy can unveil mechanisms with potential uses in prevention and treatment of cancer in humans. On the other hand, the immune system is important in preventing the development of clinically relevant tumours by maintaining a fine equilibrium between reactive and suppressive lymphocyte clones. It is suggested here that the loss of this equilibrium is what ultimately leads to increased risk of cancer and to propose a mechanism for the changes in clonal proportions based on decreased proliferative capacity of lymphocyte clones as a natural phenomenon of ageing. This mechanism, being a function of the number of cells, provides an explanation for Peto’s Paradox.

Apoptosis and proliferation ofperipheral blood T-cells as alternative processes in pathogenesis of diabetes mellitus type 1

Apoptosis, along with proliferation, is a form of lymphocyte response to activating stimuli. In the early stages of cell differentiation, the apoptotic response prevails and it results to the formation of tolerance to inductor antigen. Mature lymphocytes proliferate in response to stimulation and it means the initial stage in the development of the immune response. Since in this case apoptosis and proliferation acts as alternative processes, their ratio can serve as a measure of the effectiveness of the cellular response to activating signals. The resistance of autoreactive T-cells to apoptosis is the main key point in the development of type 1 diabetes mellitus (T1DM). Autoreactive T-cells migrates from the bloodstream to the islet tissue of the pancreas and take an active part in b cells destruction. The resistance of autoreactive effector T-cells to apoptosis may suggest their high proliferative potential. Therefore, the comparative evaluation of apoptosis and proliferation of peripheral blood lymphocytes can give a more complete picture of their functional state and thus will help to reveal the causes of ineffective peripheral blood T-ceiis apoptosis in patients with T1DM and will help to understand more deeply the pathogenesis of the disease. in this article, the features of proliferative response of peripheral blood T-cells in patients with T1DM and in individuals with high risk of developing T1DM have been studied. Apoptosis of T-cell subpopulations has been investigated. The correlation between the apoptotic markers and the intensity of spontaneous and activation- induced in vitro T-cells proliferation of was revealed. it was determined, that autoreactive peripheral blood T-cells were resistant to apoptosis and demonstrated the increased proliferative potential in patients with T1DM and in individuals with high risk of developing T1DM.

Autoimmune Regulator Enhanced the Expression of Caspase-3 and Did Not Induce Massive Germ Cell Apoptosis in GC1-Spg Cells.

AIRE is known for its involvement in autoreactive T-cell deletion in thymic epithelium. Though extrathymic expression of AIRE is well documented, the functional relevance of AIRE in non-thymus tissues is emerging. AIRE is expressed in neonatal and adult testis, and has been implicated in sporadic germ cell apoptosis in developing testis. In this study we examined whether AIRE has any role in inducing apoptosis in cultured spermatogonial cells. We over-expressed AIRE or CARD domain of AIRE in GC1-spg cells and evaluated its impact on cell cycle using fluorescence activated cell sorting following Hoechst 33342 staining. Apoptosis was assayed using Annexin-V staining. Caspase-3 cleavage was assessed on western blots and caspase-3 expression was quantitated using realtime PCR. We report that C18-4 cells which are derived from Type A spermatogonia expressed AIRE, while GC1-spg which is closer to Type B spermatogonia was negative for AIRE expression. Overexpression of AIRE or CARD domain of AIRE induced Caspase-3 expression in GC1-spg cells. Silencing of AIRE in C18-4 cells inhibited Caspase-3 expression. When overexpressed, AIRE and CARD brought about a very negligible increase in germ cell death and resulted in altered cell cycle pattern with a reduction in G1 phase. This was not associated with any increase in activation of Caspase-3. We conclude that the CARD domain of AIRE enhances caspase-3 expression through possible direct DNA binding and triggers non-apoptotic downstream signaling in cultured spermatogonial cells.

Challenges for labeling and longitudinal tracking of adoptively transferred autoreactive T lymphocytes in an experimental type-1 diabetes model.

Tracking the autoreactive T-cell migration in the pancreatic region after labeling with fluorinated nanoparticles (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-[3-(2-pyridyldithio)propionate]-perfluoro-15-crown-5-ether nanoparticles, PDP-PFCE NPs) in a diabetic murine model using 19F MRI. Synthesis of novel PDP-PFCE fluorine tracer was performed for in vitro labeling of T cells. Labeling conditions were optimized using different PDP-PFCE NPs concentrations. For in vivo 19F MRI, mice were longitudinally followed after adoptive transfer of activated, autoreactive, labeled T cells in NOD.SCID mice. Established MR protocols were used for challenging T cell labeling to track inflammation in a model of diabetes after successful labeling of CD4+ and CD8+ T cells with PDP-PFCE NPs. However, T cells were difficult to be detected in vivo after their engraftment in animals. We showed successful in vitro labeling of T cells using novel fluorinated liposomal nanoparticles. However, insufficient and slow accumulation of labeled T cells and subsequent T cell proliferation in the pancreatic region remains as limitations of in vivo cell imaging by 19F MRI.

A T-cell receptor escape channel allows broad T-cell response to CD1b and membrane phospholipids

CD1 proteins are expressed on dendritic cells, where they display lipid antigens to T-cell receptors (TCRs). Here we describe T-cell autoreactivity towards ubiquitous human membrane phospholipids presented by CD1b. These T-cells discriminate between two major types of lipids, sphingolipids and phospholipids, but were broadly cross-reactive towards diverse phospholipids including phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine. The crystal structure of a representative TCR bound to CD1b-phosphatidylcholine provides a molecular mechanism for this promiscuous recognition. We observe a lateral escape channel in the TCR, which shunted phospholipid head groups sideways along the CD1b-TCR interface, without contacting the TCR. Instead the TCR recognition site involved the neck region phosphate that is common to all major self-phospholipids but absent in sphingolipids. Whereas prior studies have focused on foreign lipids or rare self-lipids, we define a new molecular mechanism of promiscuous recognition of common self-phospholipids including those that are known targets in human autoimmune disease.

Implications of immunotherapy with high-dose glatiramer acetate in acute phase of spinal cord injury in rats

Objective: Recently, many researches with different viewpoints have focused on application of immunotherapy agents in treatment of spinal cord injury (SCI) according to neuroprotective results in some neurodegenerative disease. Glatiramer acetate (GA) is the most commonly used drug for Multiple sclerosis (MS) patients that exerts an immunomodulatory effect against Myelin basic protein (MBP) antigen.Materials and methods: High-dose (2mg/kg) treatment of GA for 28 consecutive days after SCI was compared with its low-dose (0.5 mg/kg) treatment, SCI control and Sham control rat groups.Results: High-dose GA group had significantly worsened outcome in standard functional recovery evaluation test (BBB) 12 weeks after SCI compared to SCI control and low-dose GA groups, which was confirmed by augmented spinal cavity volume and reduced ventral horn motor neurons in high-dose GA group; however, there was no significant difference between low-dose GA and control SCI group. In addition, proliferation test performed on lymphocytes from spleen and lymph nodes one week after SCI showed that high-dose GA injection has more significant effect on Division Index (DI) in response to MBP stimulation compared to low-dose GA and control SCI groups, which was associated with significant increase in IFN-γ, IL-4, and IL-17A secretion.Conclusion: Along with confirmation of deleterious aspects of autoimmunity resulting from autoreactive lymphocytes against myelin antigens in SCI, this study has shown that high-dose immunotherapy using GA, especially in acute phase after SCI, overwhelms any neuroprotective effect of adoptive immune system.

Management of Type 1 diabetes mellitus with autologous mesenchymal stem cells

Type 1 diabetes mellitus (DM) is one of the most common chronic metabolic disorders among children. The condition is associated with dysregulation of the immune system resulting in loss of self-tolerance and destruction of pancreatic β-cells by autoreactive T-lymphocytes. Regulation of β-cell homeostasis is vital to maintain optimum blood glucose control as well as prevent the development of complications. Exogenous insulin and oral hypoglycemic agents do not achieve this, as they do not address the core pathology of type 1 DM. This report describes a case of a 17-year-old female patient with fluctuating blood glucose levels and high glycosylated hemoglobin, unresponsive to conventional therapy. After undergoing two sessions of cell-based therapy, within a year, optimum control of blood glucose was achieved along with negative anti-insulin antibodies. The patient was able to discontinue insulin and has not experienced any adverse effects till date. Improvement in general health was noticed, and the patient is now free from any symptoms associated with her former diabetic status. Mesenchymal stem cells (MSCs) possess immunomodulatory and pro-angiogenic properties, which may aid in arresting β-cell destruction. In addition, MSCs may preserve residual β-cell mass and facilitate endogenous β-cell regeneration. These cells are capable of differentiating into glucose-responsive insulin-producing cells, making them ideal candidates in treatment of and prevention of complications in T1DM.

Restricted Expression of the Thymoproteasome Is Required for Thymic Selection and Peripheral Homeostasis of CD8+ T Cells

The thymoproteasome subunit β5t is specifically expressed in cortical thymic epithelial cells (TECs) and generates unique peptides to support positive selection. In this study, using a mouse model ubiquitously expressing β5t, we showed that aberrant expression of self-peptides generated by β5t affects CD8+ Tcell homeostasis, including thymic selection and maintenance of the peripheral naive pool of CD8+ Tcells. In mice in which β5t was expressed both in cortical and medullary TECs, the abundance of CD8+ lineage thymocytes was reduced, and extra-thymic expression of β5t caused accumulation of CD8+ Tcells with the memory or exhausted phenotype and induced autoreactive Tcell responses. We found that thymoproteasomes are essential for positive selection but that the subsequent change in peptide repertoire in the medulla is also crucial for thymic selection and that β5t-derived peptide must be confined to the thymus to avoid autoimmunity in peripheral tissues.

Rheumatoid arthritis and the concept of autoimmune disease

We critically review the concept of autoimmunity in Rheumatoid Arthritis (RA). To classify a disease as autoimmune, it is necessary to demonstrate that the immune response to a self-antigen causes the observed pathology. In RA, neither autoantigens nor autoreactive T-cell clones were found. Molecular mimicry exists in some cases, e.g. after Proteus mirabilis infection. In some patients, cross-reactivity between microbial DnaJ and human HSP40 can occur. However, none of the autoantibodies described in RA, with perhaps exception of Anti-Citrullinated Peptides Antibodies (ACPAs), are responsible for the onset of disease and tissue damage. ACPAs appeared early in the disease process and could activate macrophages. In turn, this leads to the release of pro-inflammatory cytokines that stimulate synovial fibroblasts. In this disease, neither autoantibodies, nor leucocytes destroy bone and cartilage. This is caused by aggressive epigenetically modified synovial fibroblasts. Current treatments did not directly target those cells. The term “autoimmune disease” for RA should be used with caution until the link between immune phenomena and joint damage has been elucidated. However, we have to be open and to accept that RA is a heterogeneous disease. This is reflected by the large variability of responses to immunosuppressive drugs or biologicals.

The use of monoclonal antibodies in autoimmunity treatment

Recently, monoclonal antibodies (MA) have gained popularity as therapeutic agents for the treatment of autoimmune disorders. These antibodies target proinflammatory cytokines, as well as T and B cells potentially involved in the pathogenesis of such conditions. In the present work we attempt to give a systematic description of available therapeutic MA, highlight their key mechanisms of action and pinpoint their adverse effects. We believe that MA that are capable of recognizing and eliminating pathogenic T- and B-cell clones hold the most promise for medical application as biologics. Detection and identification of autoreactive lymphocyte clones is one of the most serious challenges of contemporary medicine.