Immune checkpoint molecules. Possible future therapeutic implications in autoimmune diseases Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Chuan Huang, Hao-Xian Zhu, Yuan Yao, Zhen-Hua Bian, Yu-Jian Zheng, Liang Li, Haralampos M. Moutsopoulos, M. Eric Gershwin, Zhe-Xiong Lian Abstract During host immune response, an initial and sufficient activation is required to avoid infection and cancer, yet an excessive activation bears the risk of autoimmune reactivity and disease development. This fastidious balance of the immune system is regulated by co-stimulatory and co-inhibitory molecules, also known as immune checkpoints. Both excessive co-stimulation and insufficient co-inhibition can induce the activation and proliferation of autoreactive cells that may lead to the development of autoimmune diseases. During the last decade, a growing number of new immune checkpoint receptors and ligands have been discovered, providing an attractive approach to investigate their implication in the pathogenesis of autoimmune diseases and their potential role as targets for effective therapeutic interventions. In this review, we focus on the roles and underlying mechanisms of co-stimulatory and co-inhibitory receptors and other molecules that function as immune checkpoints in autoimmune diseases such as systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis, Sjögren's syndrome, type I diabetes and inflammatory bowel disease. We also summarize previous and current clinical trials targeting these checkpoint pathways in autoimmune diseases and discuss further therapeutic implications and possible risks and challenges.

Balancing cancer immunotherapy and immune-related adverse events: The emerging role of regulatory T cells Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): T. Alissafi, A. Hatzioannou, A.I. Legaki, A. Varveri, Panayotis Verginis Abstract Advances in our understanding οf tumor immunity have prompted a paradigm shift in oncology, with the emergence of immunotherapy, where therapeutic agents are used to target immune cells rather than cancer cells. A real breakthrough in the field of immunotherapy came with the use of immune checkpoint inhibitors (ICI), namely antagonistic antibodies that block key immune regulatory molecules (checkpoint molecules), such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death protein (PD-1) and its ligand PD-L1, that under physiologic conditions suppress T cell effector function. However, despite the enormous success, a significant proportion of patients do not respond, while responses are frequently accompanied by life-threatening autoimmune related adverse events (irAEs). A major impediment in the effectiveness of ICI immunotherapy is the tumoral resistance, which is dependent on the immunosuppressive nature of tumor microenvironment (TME). Regulatory T cells (Tregs) are among the most abundant suppressive cells in the TME and their presence has been correlated with tumor progression, invasiveness as well as metastasis. Tregs are characterized by the expression of the transcription factor Foxp3 and various mechanisms ranging from cell-to-cell contact to secretion of inhibitory molecules have been implicated in their function. Notably, Tregs amply express most of the checkpoint molecules such as CTLA4, PD1 and LAG3 and therefore represent a direct target of ICI immunotherapy. Taking into consideration the critical role of Tregs in maintenance of immune homeostasis and avoidance of autoimmunity it is plausible that targeting of Tregs by ICI immunotherapy results in the development of irAEs. Since the use of ICI becomes common, and new immune checkpoint molecules are currently under clinical trials for the treatment of cancer, the occurrence of irAEs is expected to dramatically rise. Herein we review the current literature focusing on the role of Tregs in cancer evolution, ICI response and development of irAEs. Unraveling the complex mechanisms that hinder the tumor immune surveillance and in particular how ICI immunotherapy imprint on Treg activities to promote cancer regression while avoid development of irAEs, will empower the design of novel immunotherapeutic modalities in cancer with increased efficacy and diminished adverse events.

Autoinflammation: Lessons from the study of familial Mediterranean fever Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Panagiotis Skendros, Charalampos Papagoras, Ioannis Mitroulis, Konstantinos Ritis Abstract Autoinflammatory disorders represent a heterogeneous group of systemic inflammatory diseases caused by genetic or acquired defects in key components of the innate immunity. Familial Mediterranean fever (FMF) is the most common among the other clinical phenotypes of the rare hereditary periodic fevers (HPFs) syndromes. FMF is associated with mutations in the MEFV gene encoding pyrin and is characterized by recurrent, often stress-provoked attacks of fever and serositis, but sometimes also by chronic subclinical inflammation. FMF is prevalent in Greece and other countries of the eastern Mediterranean region. Over the last 17 years, our group has focused on FMF as a model suitable for the research on innate immunity and particularly the role of neutrophils. Therefore, the study of Greek patients with FMF has yielded lessons across several levels: the epidemiology of the disease in Greece, the spectrum of its clinical manifestations and potential overlaps with other idiopathic inflammatory conditions, the demonstration of its rather complex and heterogeneous genetic background and the suggestion of a novel mechanism involved in the crosstalk between environmental stress and inflammation. Mechanistically, during FMF attack, neutrophils release chromatin structures called neutrophil extracellular traps (NETs), which are decorated with bioactive IL-1β. REDD1 (regulated in development and DNA damage responses 1), that encodes a stress-related mTOR repressor, has been found to be the most significantly upregulated gene in neutrophils during disease attacks. Upon adrenergic stress, REDD1-induced autophagy triggers a pyrin-driven IL-1β maturation, and the release of IL-1β-bearing NETs. Consequently, not only the mode of action of IL-1β-targeting therapies is explained, but also new treatment prospects emerge with the evaluation of old or the design of new drugs targeting autophagy-induced NETosis. Information gained from FMF studies may subsequently be applied in more complex but still relevant inflammatory conditions, such as adult-onset Still's disease, gout, ulcerative colitis and Behçet's disease.

Type I interferon gene expression in antiphospholipid syndrome: Pathogenetic, clinical and therapeutic implications Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Eleni Xourgia, Maria G. Tektonidou Abstract Type I Interferon gene expression has been shown to play an important role in the pathogenesis of several systemic autoimmune disorders, paving the way for its potential use as a surrogate marker or a therapeutic tool. While the concept of type I interferon signature and its correlation with clinical phenotypes and disease activity, along with anti-interferon targeted therapy have been vastly investigated in patients with systemic lupus erythematosus, there is a paucity of data concerning antiphospholipid syndrome patients. In this review, we summarize the current knowledge on the pathogenetic and clinical implications of type I interferon expression in antiphospholipid syndrome and discuss the therapeutic possibility of targeting molecules along the interferon signaling pathway. A number of recent studies have shown a type I interferon gene expression induction in patients with primary antiphospholipid syndrome via the plasmacytoid dendritic cell pathway, toll like receptors (TLRs) such as TLR7 and TLR9, anti-beta2glycoprotein I antibody-mediated neutrophil activation and neutrophil extracellular traps (NETs) release in a TLR4-dependent fashion, and a subsequent B cell and plasmablast activation. An association between type I interferon expression and several demographic, clinical and laboratory characteristics including age, gender, pregnancy complications such as eclampsia, anti-beta2glycoprotein I antibodies, and a negative correlation with hydroxychloroquine and/or statin use, has been shown. Correlation of high interferon scores to worse outcomes in prospective studies could direct the initiation for a prompt treatment in high-risk populations. Potential therapeutic approaches targeting type I interferon production and signaling pathway components might include anti-interferon or interferon receptor monoclonal antibodies, or an interferon based therapeutic vaccine as was indicated from previous systemic lupus erythematosus studies, TLR inhibitors including hydroxychloroquine and anti-TLR antibodies, plasmacytoid dendritic cell inhibition, adenosine-receptor agonists, and plasmablast targeting treatments. Well-designed studies are needed to further assess the immunomodulatory potential of the above targets for therapeutic intervention in patients with primary antiphospholipid syndrome.

Genetic contributors and soluble mediators in prediction of autoimmune comorbidity Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Adrianos Nezos, Maria-Eleutheria Evangelopoulos, Clio P. Mavragani Abstract Comorbidities including subclinical atherosclerosis, neuropsychological aberrations and lymphoproliferation represent a major burden among patients with systemic autoimmune diseases; they occur either as a result of intrinsic disease related characteristics including therapeutic interventions or traditional risk factors similar to those observed in general population. Soluble molecules recently shown to contribute to subclinical atherosclerosis in the context of systemic lupus erythematosus (SLE) include among others B-cell activating factor (BAFF), hyperhomocysteinemia, parathormone (PTH) levels and autoantibodies against oxidized lipids. Variations of the 5, 10- methylenetetrahydrofolate reductase (MTHFR) gene -the main genetic determinant of hyperhomocystenemia in humans-as well the interferon regulatory factor-8 (IRF8), FcγRIIA and BAFF genes have been all linked to subclinical atherosclerosis in SLE. BAFF variants have been also found to confer increased risk for subclinical atherosclerosis and lymphoma development in Sjogren's syndrome (SS) patients. Other genes shown to be implicated in SS lymphoproliferation include genes involved a. in inflammatory responses such as the NFκB regulator Tumor necrosis factor alpha-induced protein 3 (TNFAIP3) and the Leukocyte immunoglobulin-like receptor A3 (LILRA3) immunoreceptor, b. B cell activation and signaling (BAFF/BAFF-receptor), c. type I IFN pathway such as three-prime repair exonuclease 1 (TREX1), d. epigenetic processes including DNA methylation (MTHFR rs1801133, 677T allele) and e. genomic instability (MTHFR rs1801131, 1298C allele). Emerging soluble biomarkers for SS related lymphoma include mediators of B cell growth and germinal center formation such as BAFF, FMS-like tyrosine kinase 3 ligand (Flt‐3L) and CXCL13 as well as inflammatory contributors such as inteleukin (IL)-17, IL-18, ASC, LILRA3 and the extracellular lipoprotein-associated phospholipase A2 (Lp-PLA2). In regard to fatigue and neuropsychologic features in the setting of SS, contributing factors such as BAFF variants, antibodies against neuropeptides, proteins involved in nervous system function as well as inflammatory cytokines have been reported.

Predictive markers of lymphomagenesis in Sjögren's syndrome: From clinical data to molecular stratification Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Efstathia K. Kapsogeorgou, Michael Voulgarelis, Athanasios G. Tzioufas Abstract Sjögren's syndrome (SS) is a chronic systemic autoimmune disease, affecting predominantly the exocrine glands, a large array of systemic manifestations and high risk of lymphoma development. The latter constitutes the major adverse outcome of SS contributing in the increased morbidity and mortality of the disease. The vast majority of lymphomas in SS are B-cell non-Hodgkin's lymphomas (NHL), primarily indolent mucosa-associated lymphoid tissue (MALT) lymphomas, followed by nodal marginal zone lymphomas (NMZL) and diffuse large B cell lymphomas (DLBCL). In the last 3 decades and due to the adverse impact of NHL in disease outcome, an effort has been undertaken to identify markers and models predicting patients with SS at high risk for lymphoma development. Several epidemiological, clinical, laboratory and histological parameters, some of which are evident at the time of SS diagnosis, were proved to independently predict the development of NHL. These include salivary gland enlargement, skin vasculitis/purpura, glomerulonephritis, peripheral neuropathy, Raynaud's phenomenon, lymphadenopathy, splenomegaly, cytopenias, hypocomplementemia, cryoglobulinemia, rheumatoid factor, anti-Ro/La autoantibodies, hypergammaglobulinemia, serum monoclonal gammopathy, biopsy focus score and organization of lymphocytic infiltrates in the salivary glands into ectopic germinal centers. Prediction models combining some of the afore-mentioned predictors have also been described. However, the identification of specific and sensitive molecular biomarkers, related to the process of lymphomagenesis is still pending. Recently, we described a novel biomarker the miR200b-5p micro-RNA. Low levels of this miRNA in the minor salivary glands, appears to discriminate with high specificity and sensitivity the SS patients who have from those who do not have NHL. miR200b-5p, being expressed years before the clinical onset of NHL, independently predicts NHL development with a predictive value higher than the previously published multifactorial models and has a possible role in the monitoring of therapeutic response. Thus, it is a strong candidate for the identification and follow-up of patients at risk.

Autoimmune epithelitis (Sjögren's syndrome); the impact of metabolic status of glandular epithelial cells on auto-immunogenicity Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Stergios Katsiougiannis, Roxane Tenta, Fotini N. Skopouli Abstract It is well established that distinct cell metabolic alterations strongly contribute to the modulation of innate and adaptive immune responses. In the past decade the term immunometabolism has been introduced to describe the intracellular metabolic shifts of immune cells that lead to alterations of their functions. The pathogenesis of Sjögren's syndrome (SS), also referred to as autoimmune epithelitis, is not completely understood, but strong evidence supports the central role of the salivary glandular epithelial cells which are the target cells in the initiation of the autoimmune responses. Moreover, the altered epithelial functional phenotype, observed in the salivary gland lesion, may explain their disturbed secretory as well as immunoregulatory functions. From an immunometabolic perspective we have focused our studies on the endoplasmic reticulum (ER) of the salivary gland epithelial cells (SGEC) and the implication of its altered functions in the immunogenicity of these cells in SS. We showed that ER of SGEC in SS patients in situ is stressed and extensively dilated. Using salivary gland cell cultures, we studied in vitro the effect of ER stress on the metabolic behavior and viability of the cells. ER stress induced by thapsigargin increased spliced X-box binding protein-1 (XBP-1, transcription factor that increases the transcription of UPR target genes) levels in a time-dependent manner followed by autophagy and resulted to cell apoptosis. In apoptotic cells, we observed that the autoantigens Ro52 and La were redistributed in apoptotic blebs. During the induction of ER stress autophagy rescued the cells from apoptosis acting as a protective mechanism. We have also shown that adiponectin, a multifunctional hormone, is upregulated in the SGEC of SS patients acting in an autocrine or paracrine manner in the same cells. Adiponectin through activation of AMPK, the major sensor for cell energy demands, protected SGEC from apoptosis. Our results in combination with the work of others indicate that any effort of cell adaptation to ER stress may up regulate a proinflammatory milieu. This enhances the notion that metabolic alterations of the targeted epithelial cells in SS, independently of the cause, may induce an immunogenic phenotype. Therefore, SGEC have the potential to directly regulate susceptibility to and/or severity of autoimmune responses. Since adiponectin plays a vital role in the viability of SGEC through phosphorylation of AMPK, therapeutic interventions using PPAR agonists that upregulate adiponectin and concomitantly modify the energy metabolism, may be promising candidates for therapeutic intervention in SS.

Evidence of epigenetic alterations in thrombosis and coagulation: A systematic review Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): M.D. Patsouras, P.G. Vlachoyiannopoulos Abstract Thrombosis in the context of Cardiovascular disease (CVD) affects mainly the blood vessels supplying the heart, brain and peripheries and it is the leading cause of death worldwide. The pathophysiological thrombotic mechanisms are largely unknown. Heritability contributes to a 30% of the incidence of CVD. The remaining variation can be explained by life style factors such as smoking, dietary and exercise habits, environmental exposure to toxins, and drug usage and other comorbidities. Epigenetic variation can be acquired or inherited and constitutes an interaction between genes and the environment. Epigenetics have been implicated in atherosclerosis, ischemia/reperfusion damage and the cardiovascular response to hypoxia. Epigenetic regulators of gene expression are mainly the methylation of CpG islands, histone post translational modifications (PTMs) and microRNAs (miRNAs). These epigenetic regulators control gene expression either through activation or silencing. Epigenetic control is mostly dynamic and can potentially be manipulated to prevent or reverse the uncontrolled expression of genes, a trait that renders them putative therapeutic targets. In the current review, we systematically studied and present available data on epigenetic alterations implicated in thrombosis derived from human studies. Evidence of epigenetic alterations is observed in several thrombotic diseases such as Coronary Artery Disease and Cerebrovascular Disease, Preeclampsia and Antiphospholipid Syndrome. Differential CpG methylation and specific histone PTMs that control transcription of prothrombotic and proinflammatory genes have also been associated with predisposing factors of thrombosis and CVD, such us smoking, air pollution, hypertriglyceridemia, occupational exposure to particulate matter and comorbidities including cancer, Chronic Obstructive Pulmonary Disease and Chronic Kidney Disease. These clinical observations are further supported by in vitro experiments and indicate that epigenetic regulation affects the pathophysiology of thrombotic disorders with potential diagnostic or therapeutic utility.

Epigenetic perspectives on systemic autoimmune disease Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Panagiota Karagianni, Athanasios G. Tzioufas Abstract Autoimmune diseases are characterized by increased reactivity of the immune system towards self-antigens, causing tissue damage. Although their etiology remains largely unknown, genetic, microbial, environmental and psychological factors are recognized as contributing elements. Epigenetic changes, including covalent modifications of the DNA and histones, are critical signaling mediators between the genome and the environment, and thus potent regulators of cellular functions. The most extensively studied epigenetic modifications are Cytosine DNA methylation and histone acetylation and methylation on various residues. These are thought to affect chromatin structure and binding of specific effectors that regulate transcription, replication, and other processes. Recent studies have uncovered significant epigenetic alterations in cells or tissues derived from autoimmune disease patients compared to samples from healthy individuals and have linked them with disease phenotypes. Epigenetic changes in specific genes correlate with upregulated or downregulated transcription. For instance, in many systems, reduced DNA methylation and increased histone acetylation of interferon-inducible genes correlate with their increased expression in autoimmune disease patients. Also, reduced DNA methylation of retroelements has been proposed as an activating mechanism and has been linked with increased immune reactivity, while epigenetic differences on the X chromosome could indicate incomplete dosage compensation and explain to some extent the increased susceptibility of females over males towards the development of most autoimmune diseases. Besides changes in epigenetic modifications, differences in the levels of many enzymes catalyzing the addition or removal of these marks as well as proteins that recognize them and function as effector molecules have also been detected in autoimmune patients. Although the existing knowledge cannot fully explain whether epigenetic alterations cause or follow the increased immune activation, their characterization is very useful for understanding the pathogenetic mechanisms and complements genetic and clinical studies. Furthermore, specific epigenetic marks have the potential to serve as biomarkers for disease status, prognosis, and response to treatment. Finally, epigenetic factors are currently being examined as candidate therapeutic targets.

Lessons from studying the AU-rich elements in chronic inflammation and autoimmunity Publication date: November 2019 Source: Journal of Autoimmunity, Volume 104 Author(s): Niki Lourou, Maxim Gavriilidis, Dimitris L. Kontoyiannis Abstract AU-rich elements (AREs) comprise one of the most widely studied families of regulatory RNA structures met in RNAs engaged in complex immunological reactions. A multitude of genetic, molecular, holistic and functional studies have been utilized for the analyses of the AREs and their interactions to proteins that bind to them. Data stemming from these studies brought forth a world of RNA-related check-points against infection, chronic inflammation, tumor associated immunity, and autoimmunity; and the interest to capitalize the interactions of AREs for clinical management and therapy. They also provided lessons on the cellular capabilities of post-transcriptional control. Originally thought as transcript-restricted regulators of turnover and translation, ARE-binding proteins do in fact harbor great versatility and interactivity across nuclear and cytoplasmic compartments; and act as functional coordinators of immune-cellular programs. Harnessing these deterministic functions requires extensive knowledge of their synergies or antagonisms at a cell-specific level; but holds great promise since it can provide the efficacy of combinatorial therapies with single agents.