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Low grade, chronic inflammation is a critical risk factor for immunologic dysfunction including autoimmune diseases. However, the multiplicity of complex mechanisms and lack of relevant murine models limit our understanding of the precise role of chronic inflammation. To address these hurdles, we took advantage of multi-omics data and a unique murine model with a low but chronic expression of IFN-γ, generated by replacement of the AU-rich element (ARE) in the 3' UTR region of IFN-γ mRNA with random nucleotides. Herein, we demonstrate that low but differential expression of IFN-γ in mice by homozygous or heterozygous ARE replacement triggers distinctive gut microbial alterations, of which alteration is female-biased with autoimmune-associated microbiota. Metabolomics data indicates that gut microbiota-dependent metabolites have more robust sex-differences than microbiome profiling, particularly those involved in fatty acid oxidation and nuclear receptor signaling. More importantly, homozygous ARE-Del mice have dramatic changes in tryptophan metabolism, bile acid and long-chain lipid metabolism, which interact with gut microbiota and nuclear receptor signaling similarly with sex-dependent metabolites. Consistent with these findings, nuclear receptor signaling, encompassing molecules such as PPARs, FXR, and LXRs, was detectable as a top canonical pathway in comparison of blood and tissue-specific gene expression between female homozygous vs heterozygous ARE-Del mice. Further analysis implies that dysregulated autophagy in macrophages is critical for breaking self-tolerance and gut homeostasis, while pathways interact with nuclear receptor signaling to regulate inflammatory responses. Overall, pathway-based integration of multi-omics data provides systemic and cellular insights about how chronic inflammation driven by IFN-γ results in the development of autoimmune diseases with specific etiopathological features., (Published by Elsevier Ltd.)

Type I interferons (IFNs) play essential roles in establishing and modulating host defense against microbial infection via induction of IFN-stimulated genes (ISGs) through Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. However, dysregulation of IFNs production and function could also mediate immune pathogenesis such as inflammatory autoimmune diseases and infectious diseases via aberrantly activating inflammatory responses or improperly suppressing microbial controls. Thus, IFN responses need to be tightly regulated to achieve protective immunity against microbial infection while avoiding harmful toxicity caused by improper or prolonged IFN signaling. Multiple levels of cellular and molecular events act in a cooperated manner to regulate IFN responses, in especial, post-translational modification (PTMs) of signaling molecules and epigenetic modification of gene expression programs are two important mechanisms for regulation of IFN signaling and thus critical for orchestrating IFN-mediated host immune response to the complex pathogenic or environmental stimuli. Conventional PTMs such as phosphorylation and polyubiquitylation, as well as numerous other PTMs including acetylation, ISGylation, SUMOylation and methylation have been shown to potently modulate type I IFN signaling transduction via targeting distinct signaling steps or components. Moreover, epigenetic mechanisms, such as histone modification, DNA methylation, non-coding RNAs play critical roles in regulating chromatin structure and function, leading to flexible and dynamic gene expression patterns downstream type I IFN signaling. Herein, we summarize the recent advances in the PTMs and epigenetic mechanisms in regulation of type I IFN signaling and responses. The involvement of dysregulated IFN signaling in inflammatory and autoimmune diseases are also discussed., (Copyright © 2017. Published by Elsevier Ltd.)

To assess functional differences between the microbiomes of individuals with autoimmune risk-associated human leukocyte antigen (HLA) genetics and autoimmune protection-associated HLA, we performed a metagenomic analysis of stool samples from 72 infants in the All Babies in Southeast Sweden general-population cohort and assessed haplotype-peptide binding affinities. Infants with risk-associated HLA DR3-DQ2.5 and DR4-DQ8 had a higher abundance of known pathogen-associated molecular patterns and virulence related genes than infants with protection-associated HLA DR15-DQ6.2. However, there was limited overlap in the type of inflammatory trigger between risk groups. Supported by a high Firmicutes/Bacteroides ratio and differentially abundant flagellated species, genes related to the synthesis of flagella were prominent in those with HLA DR3-DQ2.5. However, this haplotype had a significantly lower likelihood of binding affinity to flagellin peptides. O-antigen biosynthesis genes were significantly correlated with the risk genotypes and absent from protective genotype association, supported by the differential abundance of gram-negative bacteria seen in the risk-associated groups. Genes related to vitamin B biosynthesis stood out in higher abundance in infants with HLA DR3-DQ2.5/DR4-DQ8 heterozygosity compared to those with autoimmune-protective genetics. Prevotella species and genus were significantly abundant in all infant groups with high risk for autoimmune disease. The potential inflammatory triggers associated with genetic risk for autoimmunity have significant implications. These results suggest that certain HLA haplotypes may be creating the opportunity for dysbiosis and subsequent inflammation early in life by clearing beneficial microbes or not clearing proinflammatory microbes. This HLA gatekeeping may prevent genetically at-risk individuals from benefiting from probiotic therapies by restricting the colonization of those beneficial bacteria. • Inflammatory triggers are abundant in microbiomes with autoimmune risk. • HLA DR3-DQ2.5 and DR4-DQ8 induce potential inflammation through different factors. • Flagellar assembly genes are prominent in infants homozygous for HLA DR3-DQ2.5. • HLA DR3-DQ2.5 has lower peptide binding affinity to flagella than other HLA. • Vitamin B biosynthesis pathways stand out in HLA DR3-DQ2.5/DR4-DQ8 infants. [ABSTRACT FROM AUTHOR]

Understanding the regulation of efferocytosis by myeloid phagocytes is important in identifying novel targets in systemic lupus erythematosus (SLE). Cadherin-11 (CDH11), a cell adhesion molecule, is implicated in inflammatory arthritis and fibrosis and recently been shown to regulate macrophage phagocytosis. The extent and mechanism of this regulation is unknown. Our objective was to examine the extent to which CDH11 regulates myeloid phagocytes and contributes to autoimmunity and tissue inflammation. We analyzed efferocytosis in macrophages and dendritic cells (DCs) from WT and Cdh11 −/− mice and investigated the mechanisms in vitro. We investigated the role of CDH11 in disease development in vivo using the pristane induced lupus model. To translate the clinical relevance of CDH11 in human disease, we measured serum CDH11 levels in two independent pediatric SLE (pSLE) cohorts and healthy controls. Using bone marrow derived macrophages (BMDMs) and DCs (BMDCs), we found impaired efferocytosis in phagocytes from Cdh 11 −/− mice, mediated by downregulated efferocytosis receptor expression and RhoGTPase activation. Specifically, loss of CDH11 downregulated Mertk expression and Rac1 activation in BMDMs, and integrin αVβ3 expression and Cdc42 activation in BMDCs, highlighting distinct pathways. In vivo , Cdh11−/− mice displayed defective efferocytosis and increased accumulation of apoptotic debris in pristane-induced lupus. Further, Cdh11−/− mice had enhanced systemic inflammation and autoimmune inflammation with increased anti-dsDNA autoantibodies, splenomegaly, type I interferons, and inflammatory cytokines. Paradoxically, at the tissue level, Cdh11−/− mice were protected against glomerulonephritis, indicating a dual role in murine lupus. Finally, SLE patients had increased serum CDH11 compared to controls. This study highlights a novel role of CDH11 in regulating myeloid cells and efferocytosis and its potential as a contributor to development in autoimmunity murine lupus. Despite the increase in autoimmunity, Cdh11 −/− mice developed decreased tissue inflammation and damage. [Display omitted] • Absence of Cadherin-11 impairs macrophage and dendritic cell efferocytosis in vitro • Cadherin-11 deficiency impairs efferocytosis and promotes systemic inflammation in pristane-induced lupus. • Cadherin-11 deficiency enhances autoantibody production in pristane-induced lupus. • Loss of Cadherin-11 protects against renal and lung inflammation in pristane-induced lupus. • Increased serum Cadherin-11 in pediatric SLE patients. [ABSTRACT FROM AUTHOR]

A Tregs insufficiency is central to autoimmune and inflammatory diseases pathophysiology and low dose interleukin-2 (IL-2 LD) can specifically activate Tregs. To assess IL-2 LD therapeutic potential and select diseases for further clinical development, we performed an open-label, phase 2a, disease-finding, "basket trial" involving patients with one of 13 different autoimmune diseases. 81 patients treated with IL-2 LD (1 million IU/day) for 5 days, followed by fortnightly injections. The first 48 patients received diluted Proleukin®, while the subsequent 33 received ready-to-use ILT-101®. The primary endpoint was the change in Tregs at day-8 compared to baseline. Key secondary endpoints included clinical efficacy assessments using the Clinical Global Impression (CGI) scale, disease-specific scores, and EuroQL-5D-5L. Our study unveiled a universal and significant expansion and activation of Tregs, without concomitant Teffs activation, across all 13 autoimmune diseases. Both Proleukin® and ready-to-use ILT-101® demonstrated identical effects on Tregs. CGI scores reflecting activity, severity, and efficacy were significantly reduced in the overall patient population. Disease-specific clinical scores improved in five of the six disease cohorts with at least six patients, namely ankylosing spondylitis, systemic lupus erythematosus, Behçet's disease, Sjögren's syndrome, and systemic sclerosis. Urticaria was the only severe adverse event related to treatment. IL-2 LD was well-tolerated, exhibiting specific Treg activation and clinical improvements across the 13 autoimmune diseases. Tregs stimulation by IL-2 LD is a promising therapeutic strategy and IL-2 LD holds considerable promise for integration into combinatorial therapeutic approaches. • IL-2 LD can safely and selectively expand Tregs without differences between diseases. • Significant reduction in CGI for activity, severity, and efficacy across all diseases. • These results robustly support the broad therapeutic potential of IL-2 LD. [ABSTRACT FROM AUTHOR]

IL-23-activation of IL-17 producing T cells is involved in many rheumatic diseases. Herein, we investigate the role of IL-23 in the activation of myeloid cell subsets that contribute to skin inflammation in mice and man. IL-23 gene transfer in WT, IL-23RGFP reporter mice and subsequent analysis with spectral cytometry show that IL-23 regulates early innate immune events by inducing the expansion of a myeloid MDL1+CD11b+Ly6G+ population that dictates epidermal hyperplasia, acanthosis, and parakeratosis; hallmark pathologic features of psoriasis. Genetic ablation of MDL-1, a major PU.1 transcriptional target during myeloid differentiation exclusively expressed in myeloid cells, completely prevents IL-23-pathology. Moreover, we show that IL-23-induced myeloid subsets are also capable of producing IL-17A and IL-23R+MDL1+ cells are present in the involved skin of psoriasis patients and gene expression correlations between IL-23 and MDL-1 have been validated in multiple patient cohorts. Collectively, our data demonstrate a novel role of IL-23 in MDL-1-myelopoiesis that is responsible for skin inflammation and related pathologies. Our data open a new avenue of investigations regarding the role of IL-23 in the activation of myeloid immunoreceptors and their role in autoimmunity. • IL-23 induces pathogenic IL-17A+ MDL-1/CLEC5A+ neutrophil population. • IL-23R+MDL-1+ neutrophils are identified in psoriasis/psoriatic arthritis patient. • IL-23 and MDL-1 expression are correlated in multiple patient cohorts. • MDL-1+ neutrophil could be a novel treatment target for psoriasis/psoriatic arthritis. [ABSTRACT FROM AUTHOR]

Abstract T-cell resilience is critical to the immune pathogenesis of human autoimmune arthritis. Autophagy is essential for memory T cell generation and associated with pathogenesis in rheumatoid arthritis (RA). Our aim here was to delineate the role and molecular mechanism of autophagy in resilience and persistence of pathogenic T cells from autoimmune arthritis. We demonstrated "Autophagic memory" as elevated autophagy levels in CD4+ memory T cells compared to CD4+ naive T cells and in Jurkat Human T cell line trained with starvation stress. We then showed increased levels of autophagy in pathogenic CD4+ T cells subsets from autoimmune arthritis patients. Using RNA-sequencing, transcription factor gene regulatory network and methylation analyses we identified MYC as a key regulator of autophagic memory. We validated MYC levels using qPCR and further demonstrated that inhibiting MYC increased autophagy. The present study proposes the novel concept of autophagic memory and suggests that autophagic memory confers metabolic advantage to pathogenic T cells from arthritis and supports its resilience and long term survival. Particularly, suppression of MYC imparted the heightened autophagy levels in pathogenic T cells. These studies have a direct translational valency as they identify autophagy and its metabolic controllers as a novel therapeutic target. Highlights • Memory and effector CD4+ T cells from arthritis show higher autophagic levels. • Autophagic memory confers metabolic advantage to pathogenic T cells from arthritis and supports their survival and resilience. • RNA-sequencing, gene regulatory networks and methylation analyses identified MYC as a key regulator of autophagic memory. • Suppression of MYC lead to heightened autophagy levels in pathogenic T cells is validated by in-vitro inhibition of MYC. [ABSTRACT FROM AUTHOR]

IL-17-producing γδ (γδ17) T cells form a versatile subset of cells that respond rapidly to innate stimuli and support the pro-inflammatory functions of different myeloid and lymphoid lineages, being particularly critical in the early stages of inflammatory and autoimmune responses. In mice, under homeostatic conditions, these innate-like lymphocytes are pre-programmed in the fetal thymus, through an intricate process involving both T cell receptor-dependent and -independent signals, which allows them to readily produce IL-17 upon stimulation. However, given their transcriptional and epigenetic wiring, γδ17 T cells are permissive to different environmental instructions, and can readily acquire the ability to co-produce multiple cytokines, such as IFN-γ, IL-22 and GM-CSF, that further propagate inflammation. Moreover, strong IL-23 signals, which are abundantly found in autoinflammatory conditions, are able to induce de novo differentiation of γδ17 T cells from uncommitted precursors, both in mice and humans. This notwithstanding, the exact mechanisms responsible for γδ17 T cell pathogenicity and multifunctionality are still poorly understood, especially in humans. The pathogenic roles attributed to γδ17 T cells in autoimmune diseases stem mainly from their ability to recruit different inflammatory myeloid populations to the target tissue, and to modulate αβ T cell function, either by enhancing inflammatory T H 17 responses, or by restraining regulatory T reg cell activity. Given their capacity to link key inflammatory axes of innate and adaptive immunity, a better understanding of the molecular basis underpinning γδ17 T cell plasticity, and how much this feature accounts for their pathophysiological roles, may be critical for developing novel therapeutic approaches. In this review, we discuss the importance of γδ17 T cells in breaking tolerance and enhancing inflammation in various autoimmune diseases, such as multiple sclerosis, psoriasis and rheumatoid arthritis under the light of their basic biological traits, e.g. development, activation, effector functions and plasticity. [ABSTRACT FROM AUTHOR]

The most recently recognized types of immune cells, the innate lymphoid cells (ILCs), have been sub-divided according to respective distinct expression profiles of regulatory factors or/and cytokines. ILCs have also been shown to participate in a variety of beneficial immune responses, including participation in attack against pathogens and mediation of the pre-inflammatory and inflammatory responses through their production of pro-inflammatory cytokines. As such, while the ILCs exert protective effects they may also become detrimental upon dysregulation. Indeed, recent studies of the ILCs have revealed a strong association with the advent and pathogenesis of several common autoimmune diseases, including psoriasis, inflammatory bowel disease (IBD) and multiple sclerosis (MS). Though the ILCs belong to lineage negative cells that are distinctive from the Th cells, the profiles of secreted cytokines from the ILCs overlap with those of the corresponding Th subsets. Nevertheless, considering that the ILCs belong to the innate immune system and the Th cells belong to the adaptive immune system, it is expected that the ILCs should function at the early stage of diseases and the Th cells should exert predominant effects at the late stage of diseases. Therefore, it is intriguing to consider targeting of ILCs for therapy by targeting the corresponding cytokines at the early stage of diseases, with the late stage cytokine targeting mainly influencing the Th cells' function. Here, we review the knowledge to date on the roles of ILCs in various autoimmune diseases and discuss their potential as new therapeutic targets. [ABSTRACT FROM AUTHOR]

Autoimmunity and chronic inflammation recognize numerous shared factors and, as a result, the resulting diseases frequently coexist in the same patients or respond to the same treatments. Among the convenient truths of autoimmune and chronic inflammatory diseases, there is now agreement that these are complex conditions in which the individual genetic predisposition provides a rate of heritability. The concordance rates in monozygotic and dizygotic twins allows to estimate the weight of the environment in determining disease susceptibility, despite recent data supporting that only a minority of immune markers depend on hereditary factors. Concordance rates in monozygotic and dizygotic twins should be evaluated over an observation period to minimize the risk of false negatives and this is well represented by type I diabetes mellitus. Further, concordance rates in monozygotic twins should be compared to those in dizygotic twins, which share 50% of their genes, as in regular siblings, but also young-age environmental factors. Twin studies have been extensively performed in several autoimmune conditions and cumulatively suggest that some diseases, i.e. celiac disease and psoriasis, are highly genetically determined, while rheumatoid arthritis or systemic sclerosis have a limited role for genetics. These observations are necessary to interpret data gathered by genome-wide association studies of polymorphisms and DNA methylation in MZ twins. New high-throughput technological platforms are awaited to provide new insights into the mechanisms of disease discordance in twins beyond strong associations such as those with HLA alleles. [ABSTRACT FROM AUTHOR]

Molecular regulation of innate signal-initiated proinflammatory cytokine production has been extensively investigated. However, the roles of epigenetic modifiers and their underlying mechanisms in regulating innate inflammatory response and development of autoimmune diseases need to be further understood. Demethylase Kdm6a promotes gene transcription in cell-lineage specification through demethylating histone H3 lysine di/tri-methylation (H3K27me2/3), and loss of Kdm6a results in developmental defects. However, the function of Kdm6a in innate immunity and inflammation remains largely unknown. Here we found that Kdm6a, significantly downregulated via JNK pathway upon innate stimuli, promotes cytokine IL-6 and IFN-β transcription in primary macrophages during innate response. Kdm6a promoted IL-6 expression through demethylating H3K27me3 at promoter in a demethylase enzymatic activity-dependent manner. Interestingly, Kdm6a promoted IFN-β expression independent of its demethylase enzymatic activity, but through increasing transcription of IFN-β-specific enhancer-derived RNA (eRNA) S-IRE1 . For the underlying mechanism, Kdm6a interacted with MLL4 and promoted MLL4 recruitment and H3K4me2 level in S-IRE1 region of Ifnb1 gene for full activation of enhancer. Our results reveal a previously unknown role of kdm6a in promoting innate IFN-β gene transcription at enhancer, in addition to demethylation at promoter. The function of Kdm6a in promoting innate inflammatory response also adds insights to better understanding of epigenetic modifiers in inflammatory and autoimmune disease. [ABSTRACT FROM AUTHOR]

Systemic lupus erythematosus (SLE) is a complex autoimmune disease where a loss of tolerance to nuclear antigens leads to inflammation in multiple organ systems. The cause of SLE remains ill defined, although it is known that a complex interplay between genes and environment is necessary for disease development. In recent years, case studies have reported that the incidence of SLE in the USA, for example, has increased by approximately 3 fold. Although the reason for this is likely to be multifactorial, it has been hypothesized that the increasing incidence of autoimmune disease is due to considerable shifts in the bacterial communities resident the gut, collectively known as the gut microbiota, following a change in diet and the widespread introduction of antibiotics. Furthermore, a growing body of evidence suggests that the gut microbiota plays a role in the development of a range of autoimmune diseases including inflammatory bowel disease, multiple sclerosis, type one diabetes and rheumatoid arthritis. In this review, we summarize how advances in DNA-based sequencing technologies have been critical in providing baseline information concerning the gut microbiota in health and how variation amongst individuals in controlled by multiples factors including age, genetics, environment and the diet. We also discuss the importance of the gut microbiota in the development of a healthy immune system and how changes in particular bacterial phyla have been associated with immune abnormalities in animal models of autoimmune disease. Finally, in order to place the data in a clinical context, we highlight recent findings showing that abnormalities in the gut microbiota can be detected in patients with SLE, which provides the rationale for greater investigation into whether microbiota-targeted therapies could be used for the treatment/prevention of disease. [ABSTRACT FROM AUTHOR]

Depicting the cellular and molecular bases of the continuous dialogue existing between the peripheral immune and the central nervous systems, as in neurolupus, is fundamental to improve, and better apprehend the role played by immune cells and mediators in the initiation and progression of neurological and psychiatric diseases, which nowadays remain a major public health issue. The relative frequency of neurological symptoms occurring in systemic autoimmunity is particularly worrying as, for example, two-thirds of patients with lupus will eventually experience the disabling effects of neuropsychiatric lupus. Neurolupus is a particularly severe form of lupus with wide-ranging symptoms, which contribute to increased mortality and morbidity in patients. In this context, infections, which suddenly trigger exacerbations of the otherwise mild lupus disease, may drive the progression of neuroinflammation and neurodegeneration via different mechanisms involving a network of effector molecules and cells. The complex interaction of neuroimmunology and neuroinfectiology represents a genuine challenge for basic scientists and clinicians to understand the mechanisms that are implicated, and identify possible biomarkers of severity that might predict the development of this devastating form of lupus. The ultimate goal is to design appropriate, personalised therapeutic strategies to improve the outcome of the disease. [ABSTRACT FROM AUTHOR]

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by multiple organ inflammatory damage and wide spectrum of autoantibodies. The autoantibodies, especially anti-dsDNA and anti-Sm autoantibodies are highly specific to SLE, and participate in the immune complex formation and inflammatory damage on multiple end-organs such as kidney, skin, and central nervous system (CNS). However, the underlying mechanisms of autoantibody-induced tissue damage and systemic inflammation are still not fully understood. Single cell analysis of autoreactive B cells and monoclonal antibody screening from patients with active SLE has improved our understanding on the origin of autoreactive B cells and the antigen targets of the pathogenic autoantibodies. B cell depletion therapies have been widely studied in the clinics, but the development of more specific therapies against the pathogenic B cell subset and autoantibodies with improved efficacy and safety still remain a big challenge. A more comprehensive autoantibody profiling combined with functional characterization of autoantibodies in diseases development will shed new insights on the etiology and pathogenesis of SLE and guide a specific treatment to individual SLE patients. • The autoantibody can arise from interplay of multiple mechanisms. • Autoantibodies of SLE is highly heterogenous. • Identification of the pathogenic autoantibodies will improve the specificity of the treatment for SLE. [ABSTRACT FROM AUTHOR]

Type I IFN production is tightly controlled by host to generate efficient viral clearance without harmful immunopathology or induction of autoimmune disorders. Epigenetic regulation of type I IFN production in innate immunity and inflammatory disorders remains to be fully understood. Several tumor suppressors have been shown to regulate immune response and inflammation. However, the non-classical functions of tumor suppressors in innate immunity and inflammatory diseases need further identification. Here we report retinoblastoma protein (Rb) deficiency selectively enhanced TLR- and virus-triggered production of IFN-β which thus induced more IFN-α generation in the later phase of innate stimuli, but had no effect on the production of TNF, IL-6 and early phase IFN-α in macrophages. Rb1 fl/fl Lyz2cre + Rb-deficient mice exhibited more resistant to lethal virus infection and more effective clearance of influenza virus. Rb selectively bound Ifnb1 enhancer region, but not the promoter of Ifna4 , Tnf and Il6 , by interacting with c-Jun, the component of IFN-β enhanceosome. Then Rb recruited HDAC1 and HDAC8 to attenuate acetylation of Histone H3/H4 in Ifnb1 promoter, resulting in suppression of Ifnb1 transcription. Therefore, Rb selectively inhibits innate IFN-β production by enhancing deacetylation of Ifnb1 promoter, exhibiting a previous unknown non-classical role in innate immunity, which also suggests a role of Rb in the regulation of type I IFN production in inflammatory or autoimmune diseases. [ABSTRACT FROM AUTHOR]

Environmental factors contribute to development of autoimmune diseases. For instance, human autoimmune arthritis can associate with intestinal inflammation, cigarette smoking, periodontal disease, and various infections. The cellular and, molecular pathways whereby such remote challenges might precipitate arthritis or flares remain unclear. Here, we used a transfer model of self-reactive arthritis-inducing CD4 + cells from KRNtg mice that, upon transfer, induce a very mild form of autoinflammatory arthritis in recipient animals. This model enabled us to identify external factors that greatly aggravated disease. We show that several distinct challenges precipitated full-blown arthritis, including intestinal inflammation through DSS-induced colitis, and bronchial stress through Influenza infection. Both triggers induced strong IL-17 expression primarily in self-reactive CD4 + cells in lymph nodes draining the site of inflammation. Moreover, treatment of mice with IL-1β greatly exacerbated arthritis, while transfer of KRNtg CD4 + cells lacking IL-1R significantly reduced disease and IL-17 expression. Thus, IL-1β enhances the autoaggressive potential of self-reactive CD4 + cells, through increased Th17 differentiation, and this influences inflammatory events in the joints. We propose that diverse challenges that cause remote inflammation (lung infection or colitis, etc.) result in IL-1β-driven Th17 differentiation, and this precipitates arthritis in genetically susceptible individuals. Thus the etiology of autoimmune inflammatory arthritis likely relates to diverse triggers that converge to a common pathway involving IL-1β production and Th17 cell distribution. [ABSTRACT FROM AUTHOR]

The migration of Th17 cells into central nervous system (CNS) tissue is the key pathogenic step in experimental autoimmune encephalomyelitis (EAE) model. However, the mechanism underlying the pathogenic Th17 cell migration remains elusive. Here we report that blockade of CD47 with CD47-Fc fusion protein is effective in preventing and curing EAE by impairing infiltration of Th17 cells into CNS. However, CD47 deficiency does not directly impair the migration of Th17 cells. Mechanistic studies showed that CD47 deficiency inhibited degradation of inducible nitric oxide synthase (iNOS) in proteasome of macrophages by Src activation and led to the increased nitric oxide (NO) production. Then NO suppressed inflammasome activation-induced IL-1β production. This lower IL-1β reduces the expression of IL-1R1 and migration-related chemokine receptors on CD47 −/− Th17 cells, inhibiting the ability of Th17 cells to infiltrate into the CNS of CD47 −/− mice and therefore suppressing EAE development. In vivo administration of exogenous IL-1β indeed promoted the infiltration CD47 −/− Th17 cells into CNS and antagonized the protective role of CD47 deficiency in EAE pathogenesis. Our results demonstrate a potential preventive and therapeutic application of CD47 blockade in controlling EAE development. [ABSTRACT FROM AUTHOR]

Autoantibodies are a hallmark of autoimmune diseases, such as rheumatoid arthritis, autoimmune hepatitis, and systemic lupus erythematosus (SLE). High titers of anti-nuclear antibodies are used as surrogate marker for SLE, however their contribution to pathogenesis remains unclear. Using murine model of SLE and human samples, we studied the effect of immune stimulation on relapsing of SLE. Although autoantibodies bound to target cells in vivo , only additional activation of CD8 + T cells converted this silent autoimmunity into overt disease. In mice as well as in humans CD8 + T cells derived IFN-γ enhanced expression of Fc-receptors on CD11b + cells. High expression of Fc-receptors allowed CD11b + cells to bind to antibody covered target cells and to destroy them in vivo . We found that autoantibodies induce clinically relevant disease when adaptive immunity, specific for disease non-related antigen, is activated. [ABSTRACT FROM AUTHOR]

Most autoimmune diseases (AID) are linked to an imbalance between autoreactive effector T cells (Teffs) and regulatory T cells (Tregs). While blocking Teffs with immunosuppression has long been the only therapeutic option, activating/expanding Tregs may achieve the same objective without the toxicity of immunosuppression. We showed that low-dose interleukin-2 (ld-IL-2) safely expands/activates Tregs in patients with AID, such HCV-induced vasculitis and Type 1 Diabetes (T1D). Here we analyzed the kinetics and dose-relationship of IL-2 effects on immune responses in T1D patients. Ld-IL-2 therapy induced a dose-dependent increase in CD4 + Foxp3 + and CD8 + Foxp3 + Treg numbers and proportions, the duration of which was markedly dose-dependent. Tregs expressed enhanced levels of activation markers, including CD25, GITR, CTLA-4 and basal pSTAT5, and retained a 20-fold higher sensitivity to IL-2 than Teff and NK cells. Plasma levels of regulatory cytokines were increased in a dose-dependent manner, while cytokines linked to Teff and Th17 inflammatory cells were mostly unchanged. Global transcriptome analyses showed a dose-dependent decrease in immune response signatures. At the highest dose, Teff responses against beta-cell antigens were suppressed in all 4 patients tested. These results inform of broader changes induced by ld-IL-2 beyond direct effects on Tregs, and relevant for further development of ld-IL-2 for therapy and prevention of T1D, and other autoimmune and inflammatory diseases. [ABSTRACT FROM AUTHOR]

Here, I consider how benign autoimmunity, the immunological homunculus, can be used to reinstate the healthy regulation of inflammation in both autoimmune diseases and in tumor immunotherapy. Different autoimmune diseases manifest clinically distinct phenotypes, but, in general, they all result from the transition of benign, healthy recognition of key body molecules into a damaging effector reaction. Tumors, in contrast to autoimmune diseases, grow by subverting the immune system into supporting and protecting the growing tumor from immune surveillance. Therefore our therapeutic aim in autoimmune disease is to induce the immune system to down-regulate the specific autoimmune effector reaction that causes the disease; in tumor immunotherapy, on the contrary, we aim to deprive the growing tumor of its illicit activation of immune suppression and to unleash an autoimmune disease targeted to the tumor. The recent success of anti-PD1 and anti-CTLR4 treatments exemplify the reinstatement of tumor autoimmunity subsequent to inhibition of immune suppression. With regard to the therapy of autoimmune diseases, I cite examples of immune system down-regulation of autoimmune diseases by T cell vaccination or HSP60 peptide treatment. Inducing the immune system to regulate itself is safer than global immune suppression and may be more effective in the long run. [ABSTRACT FROM AUTHOR]

Ruth Arnon and Michael Sela profoundly influenced the development of a model system to test new therapies in multiple sclerosis (MS). Their application of the animal model, known as experimental autoimmune encephalomyelitis (EAE), for the discovery of Copaxone, opened a new path for testing of drug candidates in MS. By measuring clinical, pathologic, and immunologic outcomes, the biological implications of new drugs could be elucidated. Using EAE they established the efficacy of Copaxone as a therapy for preventing and reducing paralysis and inflammation in the central nervous system without massive immune suppression. This had a huge impact on the field of drug discovery for MS. Much like the use of parabiosis to discover soluble factors associated with obesity, or the replica plating system to probe antibiotic resistance in bacteria, the pioneering research on Copaxone using the EAE model, paved the way for the discovery of other therapeutics in MS, including Natalizumab and Fingolimod. Future applications of this approach may well elucidate novel therapies for the neurodegenerative phase of multiple sclerosis associated with disease progression. [ABSTRACT FROM AUTHOR]

The critical role of neutrophils in pathological inflammation, notably in various autoimmune disorders, is currently the focus of renewed interest. Here, we demonstrate for the first time that activation of neutrophils with various inflammatory stimuli induces the release of extracellular vesicles (EVs) that are internalized by endothelial cells (ECs), thus leading to the transfer of miR-223, miR-142–3p and miR-451 and subsequent endothelial damage. Indeed, while miR-223 has little effect on EC responses, we show that the induced expression of miR-142–3p and miR-451 in ECs results in profound cell damage, especially in inflammatory conditions, characterized by a dramatic increase in cell apoptosis, impaired angiogenic repair responses, and the induction of IL-6, IL-8, CXCL10 and CXCL11 expression. We show that the strong deleterious effect of miR-142–3p may be due in part to its ability to block the activation of ERK1/2 and eNOS-mediated signals in ECs. miR-142–3p also inhibits the expression of RAC1 , ROCK2 and CLIC4 , three genes that are critical for EC migration and angiogenic responses. Importantly, miR-223, miR-142–3p and miR-451 are markedly increased in kidney biopsies from patients with active ANCA-associated vasculitis, a severe autoimmune disease that is prototypical of a neutrophil-induced microvascular damage. Taken together, our results suggest that miR-142–3p and miR-451 released in EVs by activated neutrophils can target EC to trigger an inflammatory cascade and induce direct vascular damage, and that therapeutic strategies based on the inhibition of these miRNAs in ECs will have implications for neutrophil-mediated inflammatory diseases. • Neutrophil-derived extracellular vesicles (EVs) damage endothelium during inflammation. • miRNAs released within neutrophil EVs are internalized by endothelial cells. • miR-142–3p and miR-451 induce endothelial cell inflammation and damage. • miR-223, -142–3p and −451 are increased in kidneys with ANCA-associated vasculitis. • miR-142–3p/451: new therapeutic targets for neutrophil-mediated diseases. [ABSTRACT FROM AUTHOR]

For reasons not fully understood, patients with an organ-specific autoimmune disease have increased risks of developing autoimmune responses against other organs/tissues. We identified ICA69, a known β-cell autoantigen in Type 1 diabetes, as a potential common target in multi-organ autoimmunity. NOD mice immunized with ICA69 polypeptides exhibited exacerbated inflammation not only in the islets, but also in the salivary glands. To further investigate ICA69 autoimmunity, two genetically modified mouse lines were generated to modulate thymic ICA69 expression: the heterozygous ICA69 del/wt line and the thymic medullary epithelial cell-specific deletion Aire-ΔICA69 line. Suboptimal central negative selection of ICA69-reactive T-cells was observed in both lines. Aire-ΔICA69 mice spontaneously developed coincident autoimmune responses to the pancreas, the salivary glands, the thyroid, and the stomach. Our findings establish a direct link between compromised thymic ICA69 expression and autoimmunity against multiple ICA69-expressing organs, and identify a potential novel mechanism for the development of multi-organ autoimmune diseases. [ABSTRACT FROM AUTHOR]

Abstract: The IL-12 family modulates T cell mediated autoimmune diseases and GWAS in PBC have suggested a critical role of IL-12 and its subunits in modulating portal inflammation. We have taken advantage of an aggressive model of portal inflammation and colitis in IL-2Rα−/− mice to study the specific role of IL-12 and, in particular, the immunobiology of p40−/−IL-2Rα−/− mice. Colonies of IL-2Rα+/−, IL-2Rα−/− and p40−/−IL-2Rα−/− mice were studied for the natural history of immunopathology in liver and colon using histology and immunohistochemistry. Further, to focus on mechanisms, liver, spleen and mesenteric lymph node flow cytometry was employed to identify specific phenotypes; cytokine analysis on inflammatory cell populations was compared between groups. Finally, Real-Time PCR was used to focus on the genes involved in hepatic fibrosis. Surprisingly, p40−/−IL-2Rα−/− mice manifest more severe portal inflammation and bile duct damage, including signs of portal hypertension and liver fibrosis, but a significant reduction in colitis. Indeed, p40−/−IL-2Rα−/− mice reveal a profound hepatic CD8+ T cell infiltrate, whose major component are effector memory cells as well as enhanced hepatic Th1 but reduced Th17 responses. These observations were confirmed by Real-Time PCR analysis of fibrosis-related genes in the liver. Distinct from its canonical effects, IL-12p40 plays a critical role in autoimmune cholangitis, including hepatic fibrosis. These data take on striking significance for any proposed human trials that modulate the IL-12p40 pathway in human PBC. [Copyright &y& Elsevier]

Abstract: Primary Sjögren's syndrome (pSS) is one of the most frequent autoimmune systemic diseases, mainly characterized by ocular and oral dryness due to the progressive destruction of lachrymal and salivary glands by an inflammatory process. A noteworthy proportion of patients also features extraglandular manifestations, sometimes severe and life-threatening. Until now, its management relies mostly on symptomatic interventions, long-term monitoring, and, in patients with severe systemic complications, immunosuppressive drugs can be provided. However, recent years have seen great progresses in the understanding of the pathological processes of the disease. The central role of regulatory lymphocytes, the implication of the type 1 interferon pathway in some patients or the importance of epigenetics have been highlighted. New classification criteria have been recently published and have shed in light an international attempt for a better recognition of the patients, probably thanks to the development of new diagnostic procedures such as salivary gland ultrasonography. To facilitate the detection of treatment efficacy in clinical trials and to help in determining which subgroups of patients would have benefits from intensive therapies, a better definition of activity scores and the availability of new prognostic markers are urgent. Thereby, the development of future therapies should be based on specific molecular signatures that will enable a personalized management of each patient. This review focuses on the most striking advances in the fields of pathophysiology, diagnosis and treatment of pSS, which generate a great hope for pSS patients. [Copyright &y& Elsevier]

Abstract: Recently, a new syndrome, namely the “Autoimmune/inflammatory syndrome induced by adjuvants” (ASIA) has been defined. In this syndrome different conditions characterized by common signs and symptoms and induced by the presence of an adjuvant are included. The adjuvant is a substance capable of boosting the immune response and of acting as a trigger in the development of autoimmune diseases. Post-vaccination autoimmune phenomena represent a major issue of ASIA. Indeed, despite vaccines represent a mainstay in the improvement of human health, several of these have been implicated as a potential trigger for autoimmune diseases. Sjogren's Syndrome (SjS) is a systemic chronic autoimmune inflammatory disease characterized by the presence of an inflammatory involvement of exocrine glands accompanied by systemic manifestations. Own to the straight association between infectious agents exposure (mainly viruses) and sicca syndrome development, the possible link between vaccine and SjS is not surprising. Indeed, a few cases of SjS following vaccine delivery have been reported. At the same extent, the induction of SjS following silicone exposure has been described too. Thus, the aim of this review was to focus on SjS and its possible development following vaccine or silicone exposure in order to define another possible facet of the ASIA syndrome. [Copyright &y& Elsevier]

Abstract: The origins of autoimmunity are not yet understood despite significant advances in immunology. The trafficking of maternal cells to the offspring represents the very first immunological event in foetal life and is reinforced during lactation. The persistence of maternal cells in offspring's tissues and circulation has been associated with several autoimmune disorders. However a direct causal effect has never been demonstrated. Maternal T cells specifically targeting foetal insulin producing cells have been shown to generate islet inflammation without directly participating in this process. Our objective was to evaluate if alloreactive maternal cells could directly trigger a graft-versus host like reaction or indirectly influence the development of the offspring's regulatory T cells favouring autoimmunity. We adopted a breeding strategy comparing genetically identical offspring from either strongly alloreactive transgenic mothers compared to immunodeficient mothers. We detected maternal alloreactive T cells in the offspring and early signs of inflammation in small intestine of 6 weeks old offspring. Interestingly, CD4+ Foxp3+ regulatory T cell frequency was diminished in mesenteric lymph nodes from eight months old offspring born of alloreactive mothers compared to offspring of immunodeficient mothers. Our study favours a hypothesis where highly alloreactive maternal cell microchimerism indirectly predisposes offspring to autoimmunity. [Copyright &y& Elsevier]

Abstract: In 2011 a new syndrome termed ‘ASIA Autoimmune/Inflammatory Syndrome Induced by Adjuvants’ was defined pointing to summarize for the first time the spectrum of immune-mediated diseases triggered by an adjuvant stimulus such as chronic exposure to silicone, tetramethylpentadecane, pristane, aluminum and other adjuvants, as well as infectious components, that also may have an adjuvant effect. All these environmental factors have been found to induce autoimmunity by themselves both in animal models and in humans: for instance, silicone was associated with siliconosis, aluminum hydroxide with post-vaccination phenomena and macrophagic myofasciitis syndrome. Several mechanisms have been hypothesized to be involved in the onset of adjuvant-induced autoimmunity; a genetic favorable background plays a key role in the appearance on such vaccine-related diseases and also justifies the rarity of these phenomena. This paper will focus on protean facets which are part of ASIA, focusing on the roles and mechanisms of action of different adjuvants which lead to the autoimmune/inflammatory response. The data herein illustrate the critical role of environmental factors in the induction of autoimmunity. Indeed, it is the interplay of genetic susceptibility and environment that is the major player for the initiation of breach of tolerance. [Copyright &y& Elsevier]

Abstract: Interleukin-7 (IL-7) is a critical survival factor for lymphocytes and recent studies suggest targeting the IL-7/IL-7Rα pathway holds promise for the treatment of autoimmune diseases. Several lines of evidence, genetic as well as functional, indicate an important role for this cytokine in autoimmune inflammation: polymorphisms in the IL-7Rα have been associated with increased risk for autoimmune disease and blocking IL-7/IL-7Rα with antibodies showed therapeutic efficacy in several autoimmune mouse models. Insights are starting to emerge about the mechanisms underlying IL-7's role in autoimmunity and tolerance, revealing surprising novel functions beyond its traditional activity as a T cell survival factor. In the first part of this review, the functions of IL-7 in the immune system are concisely described, providing a basis for understanding their potential role in promoting autoimmune responses. In the second part, current knowledge about the role of IL-7 in various autoimmune conditions is reviewed. [Copyright &y& Elsevier]

Abstract: Systemic lupus erythematosus (SLE) is an autoimmune disorder that involves multiple organ systems and typically presents as a chronic inflammatory disease. Antibodies to double-stranded (ds) DNA are present in approximately 70% of patients and form nucleic acid containing immune complexes which activate dendritic cells through engagement of toll-like receptors, leading to a pro-inflammatory, pro-immunogenic milieu. In addition, anti-dsDNA antibodies deposit in kidneys to initiate glomerulonephritis. Antibodies to C1q have also been implicated in lupus nephritis and are found in 30–50% of patients. C1q is a known suppressor of immune activation and C1q deficiency is the strongest risk factor for SLE. We previously identified a subset of anti-DNA antibodies that binds the N-methyl-d-aspartate receptor. We now show that both mouse and human anti-DNA antibodies with this specificity bind C1q. These antibodies bind to Clq in glomeruli and exhibit decreased glomerular deposition in the absence of C1q. We propose that this subset of anti-DNA antibodies participates in lupus pathogenesis through direct targeting of C1q on glomeruli and also through removal of soluble C1q thereby limiting the ability of C1q to mediate immune homeostasis. [Copyright &y& Elsevier]

Abstract: The most difficult component in our understanding of human autoimmunity remains a rigorous dissection of etiological events. Indeed, the vast literature on autoimmune diseases focuses on the inflammatory response, with the hope of developing drugs that reduce inflammation. However, there is increasing recognition that understanding the immunobiology of target tissues will also have direct relevance to disease natural history, including breach of tolerance. Sjögren''s syndrome is essentially an epitheliitis and there are major changes to normal architectural salivary organization. We propose that loss of homeostasis is the initial event that precipitates inflammation and that such inflammatory response includes not only the adaptive response, but also an intense innate immune/bystander response. To understand these events this review focuses on the architecture, phenotype, function and epithelial cell organization. We further submit that there are several critical issues that must be defined to fully understand epithelial cell immunobiology in Sjögren''s syndrome, including defining epithelial cell polarity, cell–cell and cell to extracellular matrix interactions and a variety of chemical and mechanical signals. We also argue that disruption of tight junctions induces disorganization of the apical pole of salivary acinar cells in Sjögren''s syndrome. In addition, there will be a critical role of inflammatory cytokines in the apico-basal relocation of tight junction proteins. Further, the altered disorganization and relocation of proteins that participate in secretory granule formation are also dysregulated in Sjögren''s syndrome and will contribute to abnormalities of mucins within the extracellular matrix. Our ability to understand Sjögren''s syndrome and develop viable therapeutic options will depend on defining these events of epithelial cell biology. [Copyright &y& Elsevier]

Abstract: Compared with its pro-inflammatory function, the mechanisms underlying the anti-inflammatory effect of IL-6 are poorly understood. IL-6 can cooperate with TGF-β to induce IL-10 production in Th17 cells in vitro. However, the effect of IL-6 on generation of Tr1 cells and the in vivo importance of this effect are mostly uncharacterized. In this study, we showed that in vitro, IL-6 can induce the generation of IL-10-producing Tr1 cells from naïve CD4 T cells, independently of IL-27 and TGF-β. IL-6 induces IL-21 production in CD4 T cells and IL-10-inducing effect of IL-6 requires both IL-21 and IL-2. Although IL-6 cannot induce IL-10 production in CD8 T cells in a cell-autonomous manner, it can do so indirectly through promoting CD4 T cell IL-21 production. The IL-10-producing T cells induced by IL-6 have phenotypic, genetic and functional traits of Tr1 cells and can suppress LPS-induced in vivo inflammatory response in an IL-10-dependent fashion. Blockade of IL-6 in two autoimmune inflammation models, induced respectively by anti-CD3 antibody or Treg-depletion, led to reduction in IL-10-producing T cells and exacerbated inflammation of lung and intestine. Thus, we delineated critical pathways involved in IL-6-induced generation of Tr1 cells and demonstrated the importance of this event in restraining autoimmune tissue inflammation. [Copyright &y& Elsevier]

Abstract: Lupus erythematosus (LE) is an autoimmune disease with evidence for an IL-23- and IL-17-induced immunopathology. Little is known about the type of dendritic cells supporting this immune response. We recently demonstrated the strong Th1- and Th17-T-cell inducing capacity of human 6-sulfo LacNAc-dendritic cells (slanDCs), and identified slanDCs as inflammatory dermal dendritic cells in psoriasis locally expressing IL-23, TNF-α and inducible nitric oxide synthase (iNOS). In this study, we investigated the role of slanDCs in LE. Using immunohistochemistry, we identified slanDCs at increased frequency in affected skin lesions of cutaneous and systemic LE. slanDCs were found scattered in the dermal compartment and also clustered in lymph follicle-like structures. Here, they colocalized with T cells in the periphery but not with B cells in the center. The positive staining of dermal slanDCs for TNF-α indicated their pro-inflammatory status. In vitro the production of TNF-α was induced when slanDCs were cultured in the presence of serum from patients with LE. Stimulatory components of LE serum were previously identified as autoimmune complexes with ssRNA binding to TLR7 and TLR8. We found that slanDCs express mRNA for TLR7 and TLR8. slanDCs stimulated with ssRNA, selective TLR7 or TLR8 ligands responded with high-level TNF-α and IL-12 production. In contrast to slanDCs, the population of CD1c+ DCs and plasmacytoid DCs (pDCs) expressed either TLR7 or TLR8, and their production of TNF-α and IL-12 to respective ligands was far less pronounced. We conclude that slanDCs have molecular and functional features of a pro-inflammatory myeloid DC type relevant for the immunopathogenesis of LE. [Copyright &y& Elsevier]

Abstract: Primary biliary cirrhosis (PBC) has been often coined a model autoimmune disease based on the homogeneity amongst patients, the frequency and similarity of antimitochondrial antibodies, including the highly directed immune response to pyruvate dehydrogenase (PDC-E2). A significant number of patients with PBC suffer from sicca and amongst these, there are patients who also have classic Sjögren’s syndrome. Indeed, both PBC and Sjögren’s syndrome are characterized by inflammation of target epithelial elements. Both diseases can be considered on the basis of a number of other related clinical aspects, including proposed unique apoptotic features of the target tissue, the role of secretory IgA, and the frequency with which both diseases overlap with each other. Indeed, PBC may be considered a Sjögren’s syndrome of the liver, whereas Sjögren’s syndrome can be equally discussed as PBC of the salivary glands. Dissection of the genetic predispositions for both diseases and especially the molecular basis of effector mechanisms, will become critical elements in developing new therapies. [Copyright &y& Elsevier]

Abstract: Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease characterized by the production of autoantibodies against nuclear components. Lyn-deficient mice are an excellent animal model of SLE manifesting clinical, pathological and biochemical features seen in the human disease. They develop autoreactive antibodies, glomerulonephritis and show generalized inflammation, and their B cells have a hyperactive phenotype. Since loss of Lyn confers hyper-activation of phosphoinositide 3-kinase (PI3K) signaling, we studied the effect of down-modulating PI3K in Lyn-deficient mice. We found that heterozygous inactivation of the p110δ isoform of PI3K was sufficient to restrain disease in Lyn-deficient mice, leading to significantly decreased autoantibody development and autoimmune-mediated kidney pathology, and improved survival. Intriguingly, haploinsufficiency of p110δ did not dampen signaling in Lyn-deficient B cells. However, plasma cell numbers, serum immunoglobulin titers, inflammation and T cell signaling and activation were significantly moderated in Lyn−/−p110δ+/KD mice. Importantly, we have shown that haploinsufficiency of p110δ has minor effects on the B cell compartment per se but leads to significant defects in T cell activation and B cell class-switching. These studies suggest that agents targeting p110δ PI3K need not achieve full blockade of the enzyme to be of great benefit in the treatment of SLE. [Copyright &y& Elsevier]

Abstract: Previously we showed that transgenic mice expressing human HLA-DR3 gene are susceptible to PLP91–110 induced experimental autoimmune encephalomyelitis (EAE) and can serve as an animal model of multiple sclerosis (MS). HLA-DR3 mice with EAE showed increased number of CD8 T cells indicating their important role in disease pathogenesis. The role of CD8 T cells in MS, an inflammatory demyelinating disease of CNS, has been enigmatic as it has been assigned both regulatory and pathogenic roles. Therefore, to evaluate the role of CD8 T cells, we generated CD8 deficient HLA-DR3 transgenic mice (DR3.CD8−/−). Immunization with PLP91–110 led to more severe EAE in DR3.CD8−/− mice compared to HLA-DR3 mice indicating a regulatory role for CD8 T cells. Interestingly, DR3.CD8−/− mice with EAE showed decreased CNS pathology compared to DR3 mice thus suggesting a pathogenic role for CD8 T cells. We show that these two subsets of CD8 T cells can be differentiated based on the surface expression of CD122 (IL-2 Rβ chain). CD8 T cells expressing CD122 (CD8+CD122+) play a regulatory role while CD8+CD122− T cells act as a pathogenic subset. CD122 expressing CD8 T cells are the regulatory subset of CD8 T cells and regulate the encephalitogenic CD4 T cells through direct modulation of antigen presenting cells and/or through the release of immunoregulatory cytokines such as IL-10, IFNγ and TGFβ. We also showed that adoptive transfer of CD8CD122− T cells caused increased spinal cord demyelination indicating that these are pathogenic subset of CD8 T cells. Our study suggests that CD8+ T cells play both regulatory as well as pathogenic role in disease pathogenesis of EAE. A better understanding of these subsets could aid in designing novel therapy for MS patients. [Copyright &y& Elsevier]

Abstract: Immunosenescence, or ageing of the immune system, contributes to the increased morbidity and mortality seen in the elderly population. Premature immunosenescence is shown to occur in a subgroup of patients with autoimmune diseases. One of the main characteristics of immunosenescence is the expansion of CD4+CD28− T cells in the blood. In this study, we investigate the potential contribution of these cells to disease processes in a subgroup of multiple sclerosis (MS) and rheumatoid arthritis (RA) patients. Characterization of CD4+CD28− T cells in patients and healthy controls reveals that they have an inflammation-seeking effector-memory T cell phenotype with cytotoxic properties, as they expel cytotoxic granules in response to a polyclonal stimulus or MS-related autoantigens. We identify CX3CR1, the fractalkine receptor, as a selective marker to discriminate CD4+CD28− T cells from their CD4+CD28+ counterparts. CX3CR1 expression enables CD4+CD28− T cells to migrate towards a fractalkine gradient in vitro. In addition, we find increased levels of fractalkine in the cerebrospinal fluid and inflammatory lesions of MS patients. We demonstrate for the first time that CD4+CD28− T cells accumulate in MS lesions of a subgroup of patients. Moreover, we have indications that these cells are cytotoxic in the target tissue. Overall, our findings suggest that CD4+CD28− T cells migrate in response to a chemotactic gradient of fractalkine to sites of inflammation, where they contribute to the inflammatory processes in a subgroup of patients with MS and RA. [Copyright &y& Elsevier]

Abstract: Th17 cells are a subset of CD4+ T cells characterized by production of IL-17 and are known to be key participants in inflammatory reactions and various autoimmune diseases. In this study we found that a subset of human CD4+ T cells expressing MCAM (CD146) have higher mRNA levels of RORC2, IL-23R, IL-26, IL-22, IL-17A, but not IFN-γ, compared to CD4+ T cell not expressing CD146. Upon TCR stimulation with CD3/CD28, CD4+CD146+ T cells secrete significantly more IL-17A, IL-6, and IL-8 than do CD4+CD146− T cells. Low frequencies of CD4+CD146+ T cells are found in the circulation of healthy adults, but the frequency of these cells is significantly increased in the circulation of patients with inflammatory autoimmune diseases including Behcet’s, sarcoidosis and Crohn’s disease. Patterns of gene expression and cytokine secretion in these cells are similar in healthy and disease groups. In Crohn’s disease, the increase in CD4+CD146+ cells in the circulation correlates with disease severity scores. These data indicate that expression of CD146 on CD4+ T cells identifies a population of committed human Th17 cells. It is likely the expression of CD146, an endothelial adhesion molecule, facilitates adherence and migration of Th17 cells through the endothelium to sites of inflammation. [Copyright &y& Elsevier]

Abstract: CD4+ T-cell (Th) cytokines provide important regulatory and effector functions of T-cells. Among them, IL-2 plays a unique role. IL-2 is required for the generation and maintenance of regulatory T-cells (Treg) to provide lifelong protection from autoimmune disease. Whether IL-2 is also required for autoimmune disease development is less clear as Il2−/ − mice themselves spontaneously develop multi-organ inflammation (MOI). In this communication, we discuss evidence that support the thesis that IL-2 is required for the development of autoimmune response, although some aspects of autoimmune response are not regulated by IL-2. Potential IL-2-dependent mechanisms operating at specific stages of the inflammation process are presented. The interplays among Treg, IL-2, autoimmune response and adaptive immunity are discussed. Overall, available information indicates that IL-2 is a two-faced master regulator of autoimmunity: one to prevent autoimmunity while the other promotes autoimmune response. The latter is an unfortunate consequence of IL-2 function that is used to promote the adaptive immune response against foreign antigens and pathogens. [Copyright &y& Elsevier]

Abstract: B cell activating factor belonging to the TNF family (BAFF or BLyS) is a critical B cell survival factor essential for B cell maturation. BAFF transgenic (Tg) mice develop autoimmunity resembling Systemic Lupus Erythematosus (SLE) in a T cell-independent but toll-like receptor (TLR) signalling-dependent manner, requiring TLR-induced innate B cell-derived pro-inflammatory autoantibody deposition in the kidneys. Importantly, neutralizing BAFF in the clinic shows efficacy in patients with SLE, confirming its critical role in the progression of this disease in both humans and mouse models. The specific B cell types that produce autoantibodies in BAFF Tg mice are TLR-activated innate marginal zone (MZ) B cells and B1 cells, but not follicular B cells. Interestingly, in BAFF Tg mice MZ-like B cells infiltrate salivary glands whereas B1 B cells infiltrate the kidneys. To ascertain the relevance of B1 and MZ-like B cells in the development of nephritis in BAFF Tg mice, we generated genetically asplenic as well as splenectomized BAFF Tg animals. BAFF Tg mice born without a spleen lack MZ B cells, have very reduced B1a B cell numbers but a normal B1b B cell compartment. Loss of these B cell subsets failed to protect BAFF Tg mice against nephritis indicating that B1b B cells are an important subset for the development of autoimmune nephritis in BAFF Tg mice. Thus the spleen is dispensable for the development of autoimmune nephritis in BAFF Tg mice and points toward a pathogenic role for innate B1 B cells. Identifying similar innate B cells in humans may offer the possibility of more targeted B cell therapies. [Copyright &y& Elsevier]

Abstract: The role of various environmental factors in the pathogenesis of immune mediated diseases is well established. Of which, factors entailing an immune adjuvant activity such as infectious agents, silicone, aluminium salts and others were associated with defined and non-defined immune mediated diseases both in animal models and in humans. In recent years, four conditions: siliconosis, the Gulf war syndrome (GWS), the macrophagic myofasciitis syndrome (MMF) and post-vaccination phenomena were linked with previous exposure to an adjuvant. Furthermore, these four diseases share a similar complex of signs and symptoms which further support a common denominator.Thus, we review herein the current data regarding the role of adjuvants in the pathogenesis of immune mediated diseases as well as the amassed data regarding each of these four conditions. Relating to the current knowledge we would like to suggest to include these comparable conditions under a common syndrome entitled ASIA, “Autoimmune (Auto-inflammatory) Syndrome Induced by Adjuvants”. [Copyright &y& Elsevier]

Abstract: Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies particularly to nuclear antigens and by an abnormal production of proinflammatory cytokines. In the present study, we measured the levels of the proinflammatory cytokine IL-18 and its natural inhibitor, the IL-18 binding protein (IL-18BP), in sera of SLE patients at various stages of the disease. This is the first study to present IL-18BP levels in sera of SLE patients as well as the calculated, biologically active, free IL-18 concentrations that are most probably more relevant to the pathology of SLE. Sera from 48 unselective SLE patients (total of 195 samples) were obtained longitudinally with a mean follow-up period of 11.1 ± 8.9 years and were compared to sera from 100 healthy volunteers. Circulating levels of IL-18, IL-18BP and free IL-18 in the SLE patients were significantly higher than the levels of healthy controls (5 fold, 6 fold and 3 fold for IL-18, IL-18BP and free IL-18, respectively) and correlated with disease activity as scored by SLEDAI-2K. Furthermore, these levels during active disease (SLEDAI-2K ≥ 6) were higher compared to the levels measured in the sera of the same patients during remission or during mild disease (SLEDAI-2K 0–5). The high levels of IL-18 and IL-18BP in sera of active SLE patients suggest their possible role in the pathogenesis and course of the disease. However, despite the elevated levels of IL-18BP during active disease, free IL-18 remained more than 2 fold higher than the levels in healthy controls suggesting a potential benefit of administration of exogenous IL-18BP as a novel therapeutic approach for active SLE. [Copyright &y& Elsevier]

Abstract: We developed a panel of non-obese diabetic (NOD) mice deficient in major lysosomal cysteine proteases (cathepsins S, L and B) to identify protease enzymes essential for autoimmune diabetes. Null alleles for cathepsins (Cts) S, L or B were introgressed onto the NOD genetic background with 19 Idd markers at homozygosity. Diabetes onset was determined among females aged up to 6 months. We evaluated insulitis and sialadenitis in tissues using histology and computer assisted morphology. NOD mice deficient in Ctss or Ctsb were partially protected from diabetes with incidence at 33% and 28%, respectively, versus wild-type NOD (69%; p < 0.00001). NODs lacking cathepsin L (Ctsl−/−) are completely protected from IDDM, as originally shown by others. Ctsl, Ctss, or Ctsb heterozygous mice were able to develop IDDM, although incidence levels were significantly lower for Ctsb+/− (50%) and Ctsl+/− (55%) as compared to NODs (69%; p < 0.03). Ctsl−/− mice contain functional, diabetogenic T cells and an enriched Foxp3+ regulatory T cell population, and diabetes resistance was due to the presence of an expanded population of regulatory T cells. These data provide additional information about the potency of the diabetogenic T cell population in Ctsl−/− mice which were comparable in potency to wild-type NOD mice. These data illustrate the critical contribution of each of these proteases in determining IDDM in the NOD mouse and provide a useful set of models for further studies. [Copyright &y& Elsevier]