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Objectives: The analysis of annotated transcripts from genome-wide expression studies may help to understand the pathogenesis of complex diseases, such as systemic sclerosis (SSc). We performed a whole blood (WB) transcriptome analysis on RNA collected in the context of the European PRECISESADS project, aiming at characterising the pathways that differentiate SSc from controls and that are reproducible in geographically diverse populations. Methods: Samples from 162 patients and 252 controls were collected in RNA stabilisers. Cases and controls were divided into a discovery (n=79+163; Southern Europe) and validation cohort (n=83+89; Central-Western Europe). RNA sequencing was performed by an Illumina assay. Functional annotations of Reactome pathways were performed with the Functional Analysis of Individual Microarray Expression (FAIME) algorithm. In parallel, immunophenotyping of 28 circulating cell populations was performed. We tested the presence of differentially expressed genes/pathways and the correlation between absolute cell counts and RNA transcripts/FAIME scores in regression models. Results significant in both populations were considered as replicated. Results: Overall, 15 224 genes and 1277 functional pathways were available; of these, 99 and 225 were significant in both sets. Among replicated pathways, we found a deregulation in type-I interferon, Toll-like receptor cascade, tumour suppressor p53 protein function, platelet degranulation and activation. RNA transcripts or FAIME scores were jointly correlated with cell subtypes with strong geographical differences; neutrophils were the major determinant of gene expression in SSc-WB samples. Conclusions: We discovered a set of differentially expressed genes/pathways validated in two independent sets of patients with SSc, highlighting a number of deregulated processes that have relevance for the pathogenesis of autoimmunity and SSc., This work was supported by eU/eFPia/innovative Medicines initiative Joint Undertaking PrecisesaDs Grant no. 115 565.

International audience; Objective: Neutrophil extracellular traps (NET), produced by activated polymorphonuclear neutrophils (PMN), are supposed to play a role in the pathogenesis of rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease characterized by anti-citrullinated protein antibodies (ACPA). Indeed, NET contain citrullinated autoantigens and some RA autoantibodies recognize NET. However, the mechanisms by which NET trigger or perpetuate the inflammatory process in RA are hitherto not elucidated. We hypothesized that, in addition to citrullination, NET might also contain stimulatory proteins and directly activate inflammatory target cells, as PMN and macrophages. Methods: NET antigenic and inflammatory properties were analyzed in 157 healthy donors (HD) and RA patients, the largest analysis reported so far. Primary PMN and monocyte-derived macrophages were isolated and immunoglobulin G (IgG) purified. NET were induced (NETosis), isolated and quantified. NET antigenicity was analyzed by fluorescence microscopy. PMN and macrophages were stimulated with NET with/without ACPA, C1q, LL-37 or lipopolysaccharide (LPS) and cell activation was estimated by flow cytometry and ELISA. Results: PMN from RA patients produced more NET than HD PMN. We next dissected how NET mechanistically affect inflammatory cells. Particularly, we show for the first time that RA and HD NET activated both resting macrophages and PMN, but importantly RA NET were more stimulatory, leading to secretion of inflammatory cytokines and up-regulation of HLA/CD86/CD11b. IgG from ACPA-positive RA patients specifically recognized RA and even HD NET. Nevertheless, NET-induced cell activation occurs independently of immune complex formation with ACPA. Likewise, endosomal acidification was not required. Notably, we also report that complement C1q increased the NET stimulatory activity on macrophages only, due to higher expression of C1q receptors, which was further supported by the LL-37 antimicrobial peptide. In contrast, NET specifically inhibited interleukin (IL)-6 secretion by LPS-activated macrophages and not PMN, especially with C1q/LL-37. This inhibition was not mediated by NET-derived proteases or LPS neutralization and was associated with the simultaneous induction of IL-10 secretion. Conclusion: We show that NET possess both pro- and anti-inflammatory properties depending on target cells, their activation levels and C1q/LL-37. Thus, independently of ACPA, NET modulate RA chronic inflammation via this new dual activity we identified. In addition, NET may trigger autoimmunity in RA as ACPA recognize NET antigens but not non-activated PMN. Therefore, we conclude that excess of NETosis together with enhanced NET activity participate to RA pathogenesis at different levels.

International audience; Background : Although prognosis of Chronic Granulomatous Disease (CGD) has greatly improved, few studies have focused on its long-term outcome. We studied the clinical course and sequelae of CGD patients diagnosed before age 16, at various adult time points. Method : Cross-sectional French nationwide retrospective study of patients screened through the National Reference Center for Primary Immunodeficiencies (CEREDIH) registry. Results : Eighty CGD patients (71 males [88.7%], 59 X-linked [73.7%], median age 23.9 years [minimum, 16.6; maximum, 59.9]) were included, Median ages at diagnosis and last follow-up were 2.52 and 23.9 years, respectively. Seven patients underwent hematopoietic stem cell transplantation. A total of 553 infections requiring hospitalization occurred in 2017 patient-years. The most common site of infection was pulmonary (31%). Aspergillus spp. (17%) and Staphylococcus aureus (10.7%) were the commonest pathogens. A total of 224 inflammatory episodes occurred in 71 patients, mainly digestive (50%). Their characteristics as well as their annual frequency did not vary before and after age 16. Main sequelae were a small adult height and weight and mild chronic restrictive respiratory failure. At age 16, only 53% of patients were in high school. After age 30 years, 9/13 patients were working. Ten patients died during adulthood. Conclusions : Adult CGD patients displayed similar characteristics and rates of severe infections and inflammatory episodes that those of childhood. The high rate of handicap has become a matter of medical and social consideration. Careful follow-up in centers of expertise is strongly recommended and an extended indication of curative treatment by HSCT should be considered.

Resume Objectif La presence d’une auto-immunite dite aspecifique (anticorps antinucleaires sans specificites antigeniques et/ou anticorps anti-phospholipidiques (APL) – sans critere biologique ou clinique de syndrome des APL) serait associee a une infertilite feminine dite inexpliquee. L’objectif de notre etude est de reporter les caracteristiques de patientes ayant presente une grossesse sous traitement pour la presence d’anticorps aspecifiques dans leur parcours d’infertilite au sein de la procreation medicalement assistee (PMA). Methodes Dix patientes ont ete suivies prospectivement au centre de PMA du CHU de Grenoble. Les caracteristiques des patientes et de leur infertilite ont ete recueillies et evaluees. Toutes les patientes ont beneficie d’une consultation en medecine interne ainsi qu’un bilan auto-immun (anticorps antinucleaires, APL notamment) a la recherche d’une maladie auto-immune definie (critere d’exclusion). Les traitements entrepris ont ete laisses a la discretion du clinicien. Resultats Une patiente a recu une quadritherapie (heparine, antiagregant plaquettaire, prednisone et hydroxychloroquine), 5 ont recu une tritherapie, 3 une bitherapie, et une patiente une monotherapie par prednisone. Les 10 patientes ont presente une grossesse sous traitement dont 8 ont ete menees a terme sans complications. Le controle de l’auto-immunite sous traitement semble montrer une diminution du taux serique des anticorps. La tolerance a ete bonne (une reaction d’hypersensibilite retardee a l’hydrochloroquine ayant entraine l’arret du traitement). Conclusion La presence d’une auto-immunite serique aspecifique dans un contexte d’infertilite semble etre pathogene et les traitements immunomodulateurs presentent une efficacite clinique et/ou biologique. Une etude prospective interventionnelle avec un effectif plus important est necessaire pour juger de l’efficacite de tels traitements chez les patientes presentant une infertilite inexpliquee.

International audience; On average, 10 % of infertile couples have unexplained infertility. Auto-immune disease (systemic lupus erythematosus, anti-phospholipid syndrome) accounts for a part of these cases. In the last 20 years, aspecific auto-immunity, defined as positivity of auto-antibodies in blood sample without clinical or biological criteria for defined diseases, has been evoked in a subpopulation of infertile women. A systematic review was performed (PUBMED) using the MESH search terms "infertility" and "auto-immunity" or "reproductive technique" or "assisted reproduction" or "in vitro fertilization" and "auto-immunity." We retained clinical and physiopathological studies that were applicable to the clinician in assuming joint management of both infertility associated with serum auto-antibodies in women. Thyroid auto-immunity which affects thyroid function could be a cause of infertility; even in euthyroidia, the presence of anti-thyroperoxydase antibodies and/or thyroglobulin are related to infertility. The presence of anti-phospholipid (APL) and/or anti-nuclear (ANA) antibodies seems to be more frequent in the population of infertile women; serum auto-antibodies are associated with early ovarian failure, itself responsible for fertility disorders. However, there exist few publications on this topic. The methods of dosage, as well as the clinical criteria of unexplained infertility deserve to be standardized to allow a precise response to the question of the role of serum auto-antibodies in these women. The direct pathogenesis of this auto-immunity is unknown, but therapeutic immunomodulators, prescribed on a case-by-case basis, could favor pregnancy even in cases of unexplained primary or secondary infertility.

Anti-NMDA receptor antibodies encephalitis (NMDARE) is an autoimmune disease of recent discovery. Its initial clinical presentation is characterized by psychiatric-like symptoms. The objective of this study was to better describe these symptoms, in order to allow earlier identification and diagnosis. All 111 patients studied had a NMDARE confirmed in the reference center, in Lyon. All were evaluated in an emergency department, and 45 were hospitalized in psychiatry for a median of 9 days. All patients had neurological symptoms, sometimes discreet, and 21 patients had a severe neuroleptic intolerance, justifying their transfer to an appropriate department. Psychiatric symptomatology is probably not enough contributing, being especially nonspecific. Particular attention should be given during a first psychiatric episode, especially in young women, to the existence of neurological signs (amnesia, disorientation, dyskinesia). An EEG should be part of systematic check-up for a first psychiatric episode. The neuroleptic malignant syndrome or severe intolerance should question the diagnosis. The 'perfect' resemblance between certain psychiatric disorders and NMDARE question the role of anti-NMDA antibodies in the pathogenesis of these disorders outside the strict framework of encephalitis. It is a path of innovative research in the field of immuno-psychiatry.; L’encéphalite à anticorps anti-NMDA (NMDARE) est une pathologie auto-immune de découverte récente. Sa présentation clinique initiale est dominée par des symptômes d’allure psychiatrique. L’objectif de ce travail était de mieux décrire ces symptômes pour permettre un repérage et un diagnostic plus précoces. L’ensemble des 111 patients étudiés avaient une NMDARE confirmée au centre de référence à Lyon. Tous ont été évalués aux urgences, et 45 ont été hospitalisés en psychiatrie pour une durée médiane de 9 jours. Tous les patients ont présenté un moment des symptômes neurologiques, parfois discrets, et 21 patients ont présenté une intolérance sévère aux neuroleptiques, justifiant leur transfert dans un service approprié. La symptomatologie psychiatrique est probablement peu contributive, car particulièrement aspécifique. Une attention particulière devrait être portée lors d’un premier épisode psychiatrique, notamment chez la femme jeune, à l’existence de signes neurologiques (amnésie, désorientation, dyskinésies). Un EEG devrait faire partie du bilan systématique d’un premier épisode psychiatrique. Le syndrome malin des neuroleptiques ou une intolérance sévère devraient questionner le diagnostic. La ressemblance « parfaite » entre certains troubles psychiatriques et la NMDARE interrogent le rôle des anticorps anti-NMDA dans la pathogenèse de ces troubles, en dehors du cadre rigoureux de l’encéphalite. C’est une voie de recherche innovante, dans le champ de l’immuno-psychiatrie.

The link between infection and autoimmunity is not yet well understood. This study was designed to evaluate if an acute viral infection known to induce type I interferon production, like influenza, can by itself be responsible for the breakdown of immune tolerance and for autoimmunity. We first tested the effects of influenza virus on B cells in vitro. We then infected different transgenic mice expressing human rheumatoid factors (RF) in the absence or in the constitutive presence of the autoantigen (human immunoglobulin G [IgG]) and young lupus-prone mice [(NZB × NZW)F 1 ] with influenza virus and looked for B-cell activation. In vitro, the virus induces B-cell activation through type I interferon production by non-B cells but does not directly stimulate purified B cells. In vivo, both RF and non-RF B cells were activated in an autoantigen-independent manner. This activation was abortive since IgM and IgM-RF production levels were not increased in infected mice compared to uninfected controls, whether or not anti-influenza virus human IgG was detected and even after viral rechallenge. As in RF transgenic mice, acute viral infection of (NZB × NZW)F 1 mice induced only an abortive activation of B cells and no increase in autoantibody production compared to uninfected animals. Taken together, these experiments show that virus-induced acute type I interferon production is not able by itself to break down B-cell tolerance in both normal and autoimmune genetic backgrounds.

International audience; LIME (Lck-interacting membrane protein) is a transmembrane adaptor that associates with the Lck and Fyn protein tyrosine kinases and with the C-terminal Src kinase (Csk). To delineate the role of LIME in vivo, LIME-deficient mice were generated. Although Lime transcripts were expressed in immature and mature B and T cells, the absence of LIME impeded neither the development nor the function of B and T cells. TCR transgenic mice deprived of LIME showed, however, a 1.8-fold enhancement in positive selection. Since B cells and activated T cells express LIME and the related adaptor NTAL, mice lacking both adaptors were generated. Double-deficient mice showed no defect in the development and function of B and T cells, and the lack of LIME had no effect on the autoimmune syndrome that develops in aged NTAL-deficient mice. In contrast to a previous report, we further showed that this autoimmune syndrome develops in the absence of T cells. Therefore, our in vivo results refute all the previous roles postulated for LIME on the basis of studies of transformed B and T cells and demonstrate that LIME has no seminal role in the signaling cassette operated by antigen receptors and coreceptors.

The T cell marker CD26/dipeptidyl peptidase (DP) IV is associated with an effector phenotype and markedly elevated in the human CNS disorder multiple sclerosis. However, little is known about the in vivo role of CD26/DP IV in health and disease, and the underlying mechanism of its function in CNS inflammation. To directly address the role of CD26/DP IV in vivo, we examined Th1 immune responses and susceptibility to experimental autoimmune encephalomyelitis in CD26−/− mice. We show that gene deletion of CD26 in mice leads to deregulation of Th1 immune responses. Although production of IFN-γ and TNF-α by pathogenic T cells in response to myelin Ag was enhanced in CD26−/− mice, production of the immunosuppressive cytokine TGF-β1 was diminished in vivo and in vitro. In contrast to the reduction in TGF-β1 production, responsiveness to external TGF-β1 was normal in T cells from CD26−/− mice, excluding alterations in TGF-β1 sensitivity as a mechanism causing the loss of immune regulation. Natural ligands of CD26/DP IV induced TGF-β1 production in T cells from wild-type mice. However, natural ligands of CD26/DP IV failed to elicit TGF-β1 production in T cells from CD26−/− mice. The striking functional deregulation of Th1 immunity was also seen in vivo. Thus, clinical experimental autoimmune encephalomyelitis scores were significantly increased in CD26−/− mice immunized with peptide from myelin oligodendrocyte glycoprotein. These results identify CD26/DP IV as a nonredundant inhibitory receptor controlling T cell activation and Th1-mediated autoimmunity, and may have important therapeutic implications for the treatment of autoimmune CNS disease.

Schizophrenia is a severe disease whose etiopathogenic mechanisms remaining poorly understood. The autoimmune hypothesis in psychosis is supported by many studies. Peripheral inflammation or low-grade neuroinfammation may contribute to glutamatergic NMDA receptor hypofunction which is a core mechanism in schizophrenia. Anti-NMDA receptor limbic encephalitis is an outstanding topic to study the role of autoimmune process in the genesis of psychotic symptoms. This condition is associated with specific IgG anti-NR1 in CSF inducing NMDA receptor diffusion ouf of the synapse and endocytosis. Isolated psychiatric form of the disease or anti-NMDA-R antibodies detection in the sera of schizophrenic cases may suggest that some schizophrenic patients could be considered as mild-encephalitis. In our study, 5 patients (12.5%) of 40 with a first-episode of psychosis were seropositive for IgG anti-NR1 validating precedent studies in schizophrenia. While the pathogenic effects are clearly demonstrated in encephalitis, the involvement of these markers in the genesis of psychotic symptoms in schizophrenia is debated and their pathogenicity remains to be established. The identification of clinical or paraclinical features in carriers could provide new therapeutic approach aiming pathogenic mechanisms.; La schizophrénie est une pathologie sévère dont les mécanismes étiopathogéniques restent mal connus. L’hypothèse de mécanismes auto-immuns pathogènes dans les psychoses est confortée par de nombreux travaux. Une inflammation périphérique ou une neuroinflammation de bas grade sont susceptibles de contribuer à l’hypofonctionnement du récepteur glutamatergique NMDA qui est un mécanisme central dans la schizophrénie. Les encéphalites à anticorps anti-récepteur NMDA constituent un sujet passionnant pour étudier le rôle de processus auto-immuns dans la genèse de symptômes psychotiques. Cette maladie est associée de façon spécifique à des IgG anti-NR1 dans le LCR, induisant une diffusion hors de la synapse et une endocytose du récepteur. L’existence de formes psychiatriques pures et de ces anticorps dans le sérum de patients schizophrènes suggèrent que certains cas de schizophrénies pourraient être considérés comme des encéphalites frustres. Dans notre étude, 5 patients (12,5%) sur 40 ayant un premier épisode de psychose présentaient des IgG anti-NR1 sériques, confirmant les résultats de précédentes études réalisées dans la schizophrénie. Alors que les effets pathogènes sont bien démontrés dans les encéphalites, l’implication de ces marqueurs dans la genèse des symptômes psychotiques dans la schizophrénie est débattue et leur pathogénicité doit être établie. L’identification de caractéristiques cliniques ou paracliniques chez les individus qui en sont porteurs pourraient permettre de proposer des thérapeutiques plus proches des mécanismes étiopathogéniques en cause.

International audience; The human neuroendocrine enzyme glutamate decarboxylase (GAD) catalyses the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) using pyridoxal 5′-phosphate as a cofactor. GAD exists as two isoforms named according to their respective molecular weights: GAD65 and GAD67. Although cytosolic GAD67 is typically saturated with the cofactor (holoGAD67) and constitutively active to produce basal levels of GABA, the membrane-associated GAD65 exists mainly as the inactive apo form. GAD65, but not GAD67, is a prevalent autoantigen, with autoantibodies to GAD65 being detected at high frequency in patients with autoimmune (type 1) diabetes and certain other autoimmune disorders. The significance of GAD65 autoinactivation into the apo form for regulation of neu-rotransmitter levels and autoantibody reactivity is not understood. We have used computational and experimental approaches to decipher the nature of the holo → apo conversion in GAD65 and thus, its mechanism of autoinactivation. Molecular dynamics simulations of GAD65 reveal coupling between the C-terminal domain, catalytic loop, and pyridoxal 5′-phosphate–binding domain that drives structural rearrangement, dimer opening, and autoinactivation, consistent with limited proteolysis fragmentation patterns. Together with small-angle X-ray scattering and fluorescence spectroscopy data, our findings are consistent with apoGAD65 existing as an ensemble of conformations. Antibody-binding kinetics suggest a mechanism of mutually induced conformational changes, implicating the flexibility of apoGAD65 in its autoantigenicity. Although conformational diversity may provide a mechanism for cofactor-controlled regulation of neurotransmitter biosyn-thesis, it may also come at a cost of insufficient development of immune self-tolerance that favors the production of GAD65 autoantibodies.

International audience; The B cell-activating factor of the tumor-necrosis factor family (BAFF) plays a dominant role in the B cell homeostasis. By rescuing autoreactive B cells, excessive BAFF favors the development of autoimmune diseases. Given the numbers of variants of this B cell-specific cytokine, caution must be exercized when determining its serum level. Alternate splice isoforms, such as Δ3 BAFF and Δ4 BAFF, have been identified. They raise the possibility that their overproduction impact the synthesis of full-length BAFF.

International audience; The HLA-B27 is historically studied as a susceptibility factor in spondyloarthropathies and, primarily, in ankylosing spondylitis (AS). Over the recent years however, it has been rediscovered as protective factor against some severe viral infections. This is due to the high capacity of virus-specific, HLA-B27-restricted CD8+ T cells for both intrinsic (i.e. polyfunctionality, high avidity, low sensitivity to Treg cell-mediated suppression) and extrinsic (i.e. rapid and efficient antigen processing and presentation) factors. It is tempting to speculate that these two aspects are not independent and that the association of B27 molecules to autoimmunity is the downside of this superior functional efficacy which, in given genetic backgrounds and environmental conditions, can support a chronic inflammation leading to spondyloarthropathies. Still, the pathogenic role of HLA-B27 molecules in AS is elusive. Here, we focus on the biology of HLA-B27 from the genetics to the biochemistry and to the structural/dynamical properties of B27:peptide complexes as obtained from atomistic molecular dynamics simulation. Overall, the results point at the antigen presentation as the key event in the disease pathogenesis. In particular, an extensive comparison of HLA-B*2705 and B*2709 molecules, that differ in a single amino acid (Asp116 to His116) and are differentially associated with AS, indicates that position 116 is crucial for shaping the entire peptide-presenting groove.

International audience; We evaluated the impact of cytomegalovirus (CMV)-induced immune responses, autoimmune-induced immune responses, and microbial translocation on immune activation in 191 human immunodeficiency virus type 1-infected patients from the ANRS CO3 Aquitaine Cohort. All enrolled subjects had achieved long-term virological suppression during receipt of combination antiretroviral therapy (cART). HLA-DR(+)/CD38(+) expression was 16.8% among CD8(+) T cells. Independent of age, CD4(+) T-cell count, 16S ribosomal DNA load, and regulatory T-cell count, positive results of Quantiferon CMV analysis (P = .02), positive results of CMV-pp65 enzyme-linked immunosorbent spot analysis (P = .01), positive results of CMV-pp65-specific CD8(+) T-cell analysis (P = .05), and CMV seropositivity (P = .01) were associated with a higher percentage of CD8+ T cells that expressed HLA-DR+/CD38+. Autoimmune response and microbial translocation were not associated with immune activation. Therefore, the CMV-induced immune response seems to be associated with chronic immune activation in cART recipients with sustained virological suppression.

International audience; OBJECTIVES: An immune response sufficient to induce organ failure may provide protection and therapy against tumors derived from the targeted organ particularly when removal or ablation of the organ is part of the standard therapy and does not threaten survival. We have previously shown that a targeted immune response directed against the ovarian-specific protein, inhibin-α, causes ovarian failure. Here we determined whether inhibin-α autoimmunity is effective in both prevention and treatment of ovarian tumors. METHODS: A transgene consisting of the SV40 large tumor transformation antigen under the regulation of an anti-Mullerian hormone promoter (AMH-SV40Tag) was transferred by backcrossing for 12 generations to SJL/J mice producing SJL.AMH-SV40Tag (H-2(s)) females that develop a high incidence of autochthonous granulosa cell tumors. We determined whether immunization of SJL.AMH-SV40Tag female mice with the IA(s)-restricted p215-234 peptide of mouse inhibin-α was capable of preventing and treating these ovarian tumors. RESULTS: The growth of autochthonous ovarian granulosa cell tumors in SJL.AMH-SV40Tag transgenic mice was significantly inhibited in mice immunized with Inα 215-234. In addition, significant inhibition of tumor growth occurred when mice with established ovarian granulosa cell tumors were therapeutically vaccinated with Inα 215-234. CONCLUSIONS: Our results indicate that induction of ovarian-specific autoimmunity may serve as an effective way to prevent the emergence of autochthonous ovarian tumors and control the growth of established ovarian malignancies.

International audience; Following allogenic hematopoietic stem cell transplantation (HSCT), patients with autoimmune disease or hematopoietic malignancy may develop acute or chronic graft-versus-host (GvH) disease. B lymphocytes, from the recipient as well as from the donor, have recently been implicated in the pathogenesis of such disturbances. Their deleterious effects are accounted for by other tasks B lymphocytes accomplish than the antibody production. We highlight herein some recent observations in the context of B cells in the GvH disease.

Some nonpathogenic bacteria were found to have protective effects in mouse models of allergic and autoimmune diseases. These “probiotics” are thought to interact with dendritic cells during Ag presentation, at the initiation of adaptive immune responses. Many other myeloid cells are the effector cells of immune responses. They are responsible for inflammation that accounts for symptoms in allergic and autoimmune diseases. We investigated in this study whether probiotics might affect allergic and autoimmune inflammation by acting at the effector phase of adaptive immune responses. The effects of one strain of Lactobacillus casei were investigated in vivo on IgE-induced passive systemic anaphylaxis and IgG-induced passive arthritis, two murine models of acute allergic and autoimmune inflammation, respectively, which bypass the induction phase of immune responses, in vitro on IgE- and IgG-induced mouse mast cell activation and ex vivo on IgE-dependent human basophil activation. L. casei protected from anaphylaxis and arthritis, and inhibited mouse mast cell and human basophil activation. Inhibition required contact between mast cells and bacteria, was reversible, and selectively affected the Lyn/Syk/linker for activation of T cells pathway induced on engagement of IgE receptors, leading to decreased MAPK activation, Ca2+ mobilization, degranulation, and cytokine secretion. Also, adoptive anaphylaxis induced on Ag challenge in mice injected with IgE-sensitized mast cells was abrogated in mice injected with IgE-sensitized mast cells exposed to bacteria. These results demonstrate that probiotics can influence the effector phase of adaptive immunity in allergic and autoimmune diseases. They might, therefore, prevent inflammation in patients who have already synthesized specific IgE or autoantibodies.

International audience; Epigenetics signifies stable and heritable changes in gene expression without changes in the genetic code. There is a wealth of emerging evidence for such processes in promoting autoimmunity. The first clue is that inhibition of DNA methyl transferases (DNMTs) induces systemic lupus erythematosus (SLE) in animals. Similar immune-mediated disorders have been generated by injecting normal T cells incubated with DNMT inhibitors into healthy mice. Further, monozygotic twins display differences in DNA methylation that parallel discordances in SLE. Moreover, defects in DNA methylation characterize lymphocytes from SLE, synoviocytes from rheumatoid arthritis, and neural cells from multiple sclerosis patients. It has also been shown that DNA hypomethylation of T and B cells correlates with reduced DNMT efficacy and histone acetylation in SLE. Once a gene promoter has been demethylated, the gene recovers its capacity to be transcribed, e.g., genes for cytokines, activation receptors on cells, and endogenous retroviruses. This outcome has been associated with a blockage of the Erk pathway and/or a growth arrest at the G0/G1 interface of the cell cycle. Of importance is the fact that these changes can be reversed. For example, blockade of the interleukin-6 autocrine loop in SLE B cells restores DNA methylation status, thus opening new perspectives for therapy.

TLRs play an essential role in the induction of immune responses by detecting conserved molecular products of microorganisms. However, the function of TLR8 is largely unknown. In the current study, we investigated the role of TLR8 signaling in immunity in mice. We found that Tlr8–/– DCs overexpressed TLR7, were hyperresponsive to various TLR7 ligands, and showed stronger and faster NF-κB activation upon stimulation with the TLR7 ligand R848. Tlr8–/– mice showed splenomegaly, defective development of marginal zone (MZ) and B1 B cells, and increased serum levels of IgM and IgG2a. Furthermore, Tlr8–/– mice exhibited increased serum levels of autoantibodies against small nuclear ribonucleoproteins, ribonucleoprotein, and dsDNA and developed glomerulonephritis, whereas neither Tlr7–/– nor Tlr8–/–Tlr7–/– mice showed any of the phenotypes observed in Tlr8–/– mice. These data provide evidence for a pivotal role for mouse TLR8 in the regulation of mouse TLR7 expression and prevention of spontaneous autoimmunity.

International audience; Giant cell arteritis (GCA) is characterized by intimal hyperplasia and luminal obstruction leading to ischemic manifestations involving extra-cranial branches of carotid arteries and aorta. Histopathological lesions involve all layers of the arterial wall and are associated with multinucleated giant cells, fragmented internal elastic lamina and polymorphic cellular infiltrates, including T lymphocytes and macrophages. The pathophysiology of GCA is still poorly understood. After dendritic cell activation, CD4(+) T lymphocytes, T helper 1 (Th1) cells, produce interferon gamma and modulate macrophage activation and functions, and Th17 cells produce interleukin 17 (IL-17), which can induce cytokine production by macrophages and fibroblasts. Macrophages in the adventitia produce pro-inflammatory cytokines such as IL-1, IL-6 and tumor necrosis factor alpha. These cytokines promote arterial wall and systemic inflammation. Questions remain regarding the nature of the antigen(s) triggering dendritic cell activation and the mechanisms underlying vascular remodeling. Here we review recent advances in the pathogenesis of GCA, with emphasis on the interactions between cells of the immune system and components of the vessel wall, including vascular smooth muscle cells and endothelial cells, leading to vascular remodeling. Finally, we propose new areas of investigation that could help understand the triggering factors and key pathogenic events in GCA.

International audience; Partial loss-of-function mutations in several molecules involved in T-cell receptor (TCR) signaling result in inflammation and autoimmunity. How can mutations that reduce TCR signaling output, paradoxically lead to immune pathology? This review summarizes experiments demonstrating that mutations in the linker for activation of T cells (LAT) predispose toward aberrant T cell responses to antigen in the presence of normal thymic selection. In the absence of LAT, antigen-specific T cells give rise to self-perpetuating pro-inflammatory responses and induce the production of autoantibodies independently of TCR engagement. Therefore, some pathological conditions called "autoimmune" might not result from the presence of self-reactive T cells, but from defective mechanisms that normally keep T cell activation in check.

International audience; Advances in genetics, such as sequencing of the human genome, have contributed to identification of susceptible genetic patterns in autoimmune diseases (AID). However, genetics is only one aspect of the diseases that does not reflect the influence of environment, sex or aging. Epigenetics, the control of gene packaging and expression independent of alterations in the DNA sequence, is providing new directions linking genetics and environmental factors. Recent findings have contributed to our understanding of how epigenetic modifications could influence AID development, showing differences between AID patients and healthy controls but also showing how one disease differs from another. With regards to epigenetic abnormalities, DNA methylation and histone modifications could be affected leading to large spatial and temporal changes in gene regulation. Other epigenetic processes, such as the influence of the ionic milieu around chromatin and DNA supercoiling stresses may be suspected also. The newly described role of microRNAs in control of gene expression is important by promoting or suppressing autoreactivity in AID. As a consequence control of cellular processes is affected becoming conducive, for example, to the development of autoreactive lymphocytes in systemic lupus erythematosus, synoviocyte proliferation in rheumatoid arthritis, or neural demyelination in multiple sclerosis. Application of epigenetics to AID is in its infancy and requires new hypotheses, techniques, tools, and collaborations between basic epigenetic researchers and autoimmune researchers in order to improve our comprehension of AID. From this will arise new therapeutics, means for early intervention, and perhaps prevention.

International audience; Autoimmune disease (AD) affects approximately 3% of the population. This is an enormous number, but ironically the study of autoimmunity has not taken on the significance of many other diseases because so many of the ADs are relatively uncommon. Indeed, despite enormous advances in the diagnosis and the treatment of AD, there is still a paucity of data on the etiological events that lead to the clinical pathology. For most other human diseases, the etiology is addressed and often solved by the use of epidemiology. Epidemiology consists of the study of prevalence of a disease, coupled with analysis of genetic factors and detection of environmental agents. In the context of autoimmune conditions, preclinical epidemiology has recently been favored, as a consequence of the discovery that autoantibody precedes overt disease. The idea of a North-South gradient in the prevalence of ADs, with a reciprocal gradient in that of infectious injuries has proven to be debatable. More importantly, environmentally-induced changes have been shown to modify certain diseases giving rise to the key concept of epigenetics. However, it is clear that major voids exist. Some of these voids were hoped to be solved by the use of genome-wide associations. This, however, has proven very problematic, as the genetic basis of AD is considerably more complicated than once believed. We now base our hopes on next generational sequencing as a brut force undertaking to partially decipher the genetic code that predisposes individuals to AD. This volume is a compilation of papers in Autoimmunity Reviews and the Journal of Autoimmunity and presented as part of the 7th International Congress on Autoimmunity in Ljubljana, Slovenia. It is clearly impossible to present data on the geoepidemiology of all of the AD. Instead, we attempted to generate interest amongst immunologists to generate papers that are thought provoking but also contemporary reviews.

International audience; ZAP-70 is critical for T cell receptor (TCR) signaling. Tyrosine to phenylalanine mutations of Y315 and Y319 in ZAP-70 suggest these residues function to recruit downstream effector molecules, but mutagenesis and crystallization studies reveal that these residues also play an important role in autoinhibition ZAP-70. To address the importance of the scaffolding function, we generated a zap70 mutant mouse (YYAA mouse) with Y315 and Y319 both mutated to alanines. These YYAA mice reveal that the scaffolding function is important for normal development and function. Moreover, the YYAA mice have many similarities to a previously identified ZAP-70 mutant mouse, SKG, which harbors a distinct hypomorphic mutation. Both YYAA and SKG mice have impaired T cell development and hyporesponsiveness to TCR stimulation, markedly reduced numbers of thymic T regulatory cells and defective positive and negative selection. YYAA mice, like SKG mice, develop rheumatoid factor antibodies, but fail to develop autoimmune arthritis. Signaling differences that result from ZAP-70 mutations appear to skew the TCR repertoire in ways that differentially influence propensity to autoimmunity versus autoimmune disease susceptibility. By uncoupling the relative contribution from T regulatory cells and TCR repertoire during thymic selection, our data help to identify events that may be important, but alone are insufficient, for the development of autoimmune disease.

BackgroundAutoimmune diabetes (T1D) onset is preceded by a long inflammatory process directed against the insulin-secreting β cells of the pancreas. Deciphering the early autoimmune mechanisms represents a challenge due to the absence of clinical signs at early disease stages. The aim of this study was to identify genes implicated in the early steps of the autoimmune process, prior to inflammation, in T1D. We have previously established that insulin autoantibodies (E-IAA) predict early diabetes onset delineating an early phenotypic check point (window 1) in disease pathogenesis. We used this sub-phenotype and applied differential gene expression analysis in the pancreatic lymph nodes (PLN) of 5 weeks old Non Obese Diabetic (NOD) mice differing solely upon the presence or absence of E-IAA. Analysis of gene expression profiles has the potential to provide a global understanding of the disease and to generate novel hypothesis concerning the initiation of the autoimmune process.MethodsAnimals have been screened weekly for the presence of E-IAA between 3 and 5 weeks of age. E-IAA positive or negative NOD mice at least twice were selected and RNAs isolated from the PLN were used for microarray analysis. Comparison of transcriptional profiles between positive and negative animals and functional annotations of the resulting differentially expressed genes, using software together with manual literature data mining, have been performed.ResultsThe expression of 165 genes was modulated between E-IAA positive and negative PLN. In particular, genes coding for insulin and for proteins known to be implicated in tissue remodelling and Th1 immunity have been found to be highly differentially expressed. Forty one genes showed over 5 fold differences between the two sets of samples and 30 code for extracellular proteins. This class of proteins represents potential diagnostic markers and drug targets for T1D.ConclusionOur data strongly suggest that the immune related mechanisms taking place at this early age in the PLN, correlate with homeostatic changes influencing tissue integrity of the adjacent pancreatic tissue. Functional analysis of the identified genes suggested that similar mechanisms might be operating during pre-inflammatory processes deployed in tissues i) hosting parasitic microorganisms and ii) experiencing unrestricted invasion by tumour cells.

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International audience; OBJECTIVES: To examine the prevalence of cryoglobulinemia and autoimmune markers in stable liver transplant recipients and to determine risk factors and clinical impact. MATERIALS AND METHODS: Ninety-two liver transplant recipients were tested for cryoglobulinemia, hepatitis B and C, complement C3, complement C4, CH50, antinuclear antibodies, anticytoplasmic neutrophil antibodies, anticardiolipid antibodies, rheumatoid factors, and lymphocyte subpopulations. Liver, renal, and hematology tests were done. Immunosuppressive regimens were based on calcineurin inhibitors in 94.6% of the patients. RESULTS: Cryoglobulinemia was present in 18 patients (19.5%) with characteristics of type II in 27.7%, type III in 61.3%, and indeterminate in 11%. Cryoglobulinemia was present in 55.5% of patients with positive hepatitis C virus serology compared with 35.86% of patients with negative hepatitis C virus serology (P = .06). Among those with hepatitis C virus markers, cryoglobulinemia was present in 30%. Anticytoplasmic neutrophil antibodies were positive in 23% of the patients with cryoglobulinemia, but in only 5.4% of the patients without cryoglobulinemia (P = .006). Albuminemia was significantly lower in patients with cryoglobulinemia (38 -/+ 4.2 g/L) than it was in patients without cryoglobulinemia (40.2 -/+ 3.4; P = .05). Cryoglobulinemia was symptomatic in 4 patients (22.2% of all patients). Independent factors associated with cryoglobulinemia were presence of anticytoplasmic neutrophil antibodies, more than 4 HLA incompatibilities, alanine aminotransferase level of 0.68 microkat/L or more, and an albuminemia level greater than 38 g/L. CONCLUSIONS: Cryoglobulinemia is frequent after liver transplant and is symptomatic in approximately 20% of all patients.

TLR sense microbial infections, and control activation of immune responses. Dendritic cells, macrophages, and B lymphocytes express TLR and the TLR-signaling adaptor protein MyD88. The impact of TLR-activated B cells on T cell-mediated inflammation is unknown. In this study, we have used mice carrying B cell-restricted deficiencies in MyD88 or in distinct TLR to examine the impact of TLR-activated B cells on a T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis (EAE). We demonstrate that TLR-signaling in B cells suppresses inflammatory T cell responses (both Th1 and Th17), and stimulates recovery from EAE. Only certain TLR are required on B cells for resolution of EAE, and these are dispensable for disease initiation, indicating that a category of TLR agonists preferentially triggers a suppressive function in B cells and thereby limits autoimmune disease. The TLR agonists controlling the regulatory function of B cells are provided by components of Mycobacterium tuberculosis present in the adjuvant. Thus, MyD88 signaling in B cells antagonizes MyD88 signaling in other cells, which drives differentiation of Th17 cells and is required for induction of EAE. Altogether, our data indicate that B cells link recognition of microbial products via TLR to suppression of a T cell-mediated autoimmune disease.

Previously, we have shown that thiopalmitoylation of peptides of myelin proteolipid protein, as occurs naturally in vivo, increases their ability to induce experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis, and skews the autoimmune response toward a CD4+-mediated response. In contrast, the same peptide, when synthesized with a stable amide bond between peptide and lipid, inhibits experimental autoimmune encephalomyelitis and skews the response toward a CD8+ response. The aim of the current study was to determine the mechanisms responsible for these observations. We show that proteolipid protein lipopeptides, when synthesized with a thioester bond between the lipid and the peptide, are taken up into APCs via an actin-independent endocytic route, the thioester bond is cleaved in the endosome, and the peptide is subsequently displayed on the surface of the APC in the context of MHC class II. The same peptide, when synthesized with the lipid attached via a stable amide bond, rapidly enters into the cytoplasm of the APC and forms micelles; however, the bond between peptide and lipid is not cleaved, and the micelles travel via the endoplasmic reticulum to complex with MHC class I. These findings have implications for vaccine development and for the development of MHC class II-restricted autoimmune diseases, as many human autoantigens thus far identified are thioacylated.

International audience; Numerous associations have been documented between the Epstein-Barr virus (EBV) and rheumatoid arthritis (RA). Thus, anti-EBV antibody titers are higher in RA patients than in healthy controls. Lymphocytes from RA patients show impaired responses to EBV. Several EBV antigens share similarities with self antigens; more specifically, the glycine/alanine repeats in EBNA-1 resemble synovial proteins and the EBV gp110 glycoprotein contains a copy of the shared epitope. Cell-mediated responses to EBV replicative cycle proteins and to gp110 have been documented in joint fluid from RA patients. In situ hybridization and PCR techniques have identified EBV antigens and genetic material within the rheumatoid synovium, albeit with variable yields. The EBV burden in peripheral blood mononuclear cells is higher in RA patients than in controls. EBNA-1 can undergo citrullination, and the EBV can induce antibodies to citrullinated peptides. RA patients are at increased risk for lymphoma, including EBV-associated lymphoma. Despite these multiple and complex links between EBV and RA, proof of a causal association is lacking. EBV infection may contribute indirectly to the pathophysiology of RA by impairing immune control of EBV replication, causing increased exposure to EBV antigens and, thereby, chronic inflammation. The effect of biotherapies for RA on EBV-host relations needs to be investigated.

Naturally occurring variation in gene copy number is increasingly recognized as a heritable source of susceptibility to genetically complex diseases. Here we report strong association between FCGR3B copy number and risk of systemic lupus erythematosus (P = 2.7 x 10(-8)), microscopic polyangiitis (P = 2.9 x 10(-4)) and Wegener's granulomatosis in two independent cohorts from the UK (P = 3 x 10(-3)) and France (P = 1.1 x 10(-4)). We did not observe this association in the organ-specific Graves' disease or Addison's disease. Our findings suggest that low FCGR3B copy number, and in particular complete FCGR3B deficiency, has a key role in the development of systemic autoimmunity.

Using targeted mutagenesis in mice, we have blocked shedding of endogenous murine TNF by deleting its cleavage site. Mutant mice produce physiologically regulated levels of transmembrane TNF (tmTNF), which suffice to support thymocyte proliferation but cannot substitute for the hepatotoxic activities of wild-type TNF following LPS/D-galactosamine challenge in vivo and are not sufficient to support secondary lymphoid organ structure and function. Notably, however, tmTNF is capable of exerting anti-Listerial host defenses while remaining inadequate to mediate arthritogenic functions, as tested in the tristetraprolin-deficient model of TNF-dependent arthritis. Most interestingly, in the EAE model of autoimmune demyelination, tmTNF suppresses disease onset and progression and retains the autoimmune suppressive properties of wild-type TNF. Together, these results indicate that tmTNF preserves a subset of the beneficial activities of TNF while lacking detrimental effects. These data support the hypothesis that selective targeting of soluble TNF may offer several advantages over complete blockade of TNF in the treatment of chronic inflammation and autoimmunity.

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International audience; BACKGROUND: Use of a reduced-intensity conditioning regimen before an allogeneic hematopoietic cell transplantation is frequently associated with an early state of mixed hematopoietic chimerism. Such a coexistence of both host and donor hematopoietic cells may influence posttransplant alloreactivity and may affect the occurrence and severity of acute and chronic graft-versus-host disease (GVHD) as well as the intensity of the graft-versus-leukemia effect. Here we evaluated the relation between chimerism state after reduced-intensity conditioning transplantation (RICT), autoantibody production, and chronic GVHD (cGVHD)-related pathology. METHODS: Chimerism state, circulating anticardiolipin, and antidouble stranded DNA autoantibody (Ab) titers as well as occurrence of cGVHD-like lesions were investigated in a murine RICT model. RESULTS: We observed a novel association between mixed chimerism state, high levels of pathogenic IgG autoantibodies, and subsequent development of cGVHD-like lesions. Furthermore, we found that the persistence of host B cells, but not dendritic cell origin or subset, was a factor associated with the appearance of cGVHD-like lesions. The implication of host B cells was confirmed by a host origin of autoantibodies. CONCLUSION: Recipient B cell persistence may contribute to the frequency and/or severity of cGVHD after RICT.

International audience; Autoimmunity and inheritance of complex characters behold an explosive interest in biology over the last 15 years. Research in the genetics of autoimmunity has been impelled by the isolation of genetic markers allowing tracing of heredity. The annotation and sequencing of the human and mouse genomes provide with the potential for further advancements, through the development of new technologies. This review aims to summarize advances made in the autoimmunity field, centered in type 1 diabetes in the NOD mouse model. It also aims to demonstrate that animal models, albeit some phenotypic and genetic dissimilarities with the human diseases, still remain the best way to move towards an understanding of the molecular mechanisms involved in autoimmunity. Assessing the current state of research in this field together with the increasing potential of novel biotechnology advancements, new insights to disease pathogenesis and discovery of molecular targets for intervention strategies are anticipated in the coming years. D

International audience; The molecular mechanisms initiating the autoimmune process in type 1 diabetes mellitus (T1DM) remain unknown, and studies aiming to address this question have been compromised by the difficulty of predicting the disease at an early age both in humans and in animal models. An additional hindrance in selecting individuals at an early age has been the complex genetic inheritance of autoimmune diabetes, implicating not only several genes but also environmental factors. We have previously demonstrated the predictive value of insulin autoantibodies (IAAs) at an early age, between three to five weeks in the NOD mouse. Animals positive for early appearance of IAAs (E-IAAs) develop auto-immune diabetes earlier. We showed a correlation between the presence of IAAs in the mothers during pregnancy, E-IAAs in the litters, and the early appearance of T1DM. NOD mice, E-IAA–positive, within litters from IAA-positive mothers during pregnancy, develop diabetes earlier and at a much greater rate than animals that are IAA-negative and from IAA-negative mothers. The molecular mechanisms responsible for this early autoimmune subphenotype were addressed by a global approach to differential gene expression analysis in the pancreatic lymph nodes (PaLNs). Although the data analysis is currently in progress, gene expression signatures were observed that are characteristic for PaLNs with regard to the presence or absence of IAAs. Overall, these data are consistent with the hypothesis of an early environmental influence from the autoimmune maternal environment on the genetic predisposition of the offspring, characterized by specific gene signatures leading to autoimmune disease.

International audience; B cell tolerance or autoimmunity is determined by selective events. Negative selection of self-reactive B cells is well documented and proven. In contrast, positive selection of conventional B cells is yet to be firmly established. Here, we demonstrate that developing self-reactive B cells are not always highly sensitive to the deletion mechanisms imposed by membrane-bound self-antigens. At low amounts, membrane-bound antigens allow survival of B cells bearing a single high affinity self-reactive B cell receptor (BCR). More importantly, we show that forced allelic inclusion modifies B cell fate; low quantities of self-antigen induce the selection and accumulation of increased numbers of self-reactive B cells with decreased expression of antigen-specific BCRs. By directly measuring antigen binding by intact B cells, we show that the low amounts of self-antigen select self-reactive B cells with a lower association constant. A fraction of these B cells is activated and secretes autoantibodies that form circulating immune complexes with self-antigen. These findings demonstrate that conventional B cells can undergo positive selection and that the fate of a self-reactive B cell depends on the quantity of self-antigen, the number of BCRs engaged, and on its overall antigen-binding avidity, rather than on the affinity of individual BCRs.

International audience; During its primary encounter with a pathogen, the immune system has to decide which type of immune response is most appropriate. Based on signals from the innate immune system and the immunological context in which the pathogen is presented, responding lymphocytes will adopt a particular phenotype, e.g. secrete a particular profile of cytokines. Once stimulated, lymphocytes store the appropriate type of response by differentiating from a naive to a memory phenotype. This allows the appropriate type of immune reaction to be regenerated upon re-stimulation of those memory clones. We developed a computer simulation model in which cross-reacting effector/memory clones contribute to the immunological context of pathogens. If a pathogen is recognized by both naive clones and pre-existing effector/memory clones, the naive lymphocytes adopt the effector mechanism of the memory clone. The adaptive immune system thereby stores immunological decisions and somatically learns to induce the right type of immune response to pathogens sharing epitopes. The influence of effector/memory lymphocytes may be detrimental when they cross-react to new pathogens that require a different kind of immune response. Here, we show that the immune system needs to be sufficiently specific to avoid such mistakes and to profit from the information that is stored in effector/memory lymphocytes. Repertoire diversity is required to reconcile this specificity with reactivity against many pathogens.

International audience; In this essay we suggest that the primary goal of the cells of the immune system is to ensure their own growth and survival. In adults, in steady-state conditions, the number and distribution of lymphocyte populations is under homeostatic control. New lymphocytes that are continuously produced in primary and secondary lymphoid organs must compete with resident cells for survival. We discuss recent findings supporting lymphocyte survival as a continuous active process and implicating cognate receptor engagement as fundamental survival signals for both T and B lymphocytes. The conflict of survival interests between different cell types gives rise to a pattern of interactions that mimics the behavior of complex ecological systems. In their flight for survival and in response to competition, lymphocytes use different survival signals within different ecological niches during cell differentiation. This is the case for T and B lymphocytes and also for naive and memory/activated T and B cells. We discuss how niche differentiation allows the co-existence of different cell types and guarantees both repertoire diversity and efficient immune responses.

The T cell receptor (TCR) is functionally coupled to a constellation of ten immunoreceptor tyrosine–based activation motifs (ITAMs). A new study suggests that this large number of ITAMs is mandatory for preventing autoimmunity.

OBJECTIVE: To characterize autoantibody response to poly(ADP-ribose) polymerase (PARP) and to assess the significance of autoantibodies to the 2 zinc fingers of this enzyme in patients with autoimmune rheumatic and bowel diseases. METHODS: The specificity of antienzyme autoantibodies was established by dot immunoassay with recombinant human PARP and by enzyme-linked immunosorbent assay using the recombinant N-terminal fragment containing the DNA binding domain of PARP, the recombinant C-terminal catalytic domain (40-kd fragment), a peptide containing the nuclear localization signal (NLS) of PARP, 2 synthetic peptides (and mutated peptides) corresponding to zinc-finger motifs F1 and F2 that are present in the DNA binding domain, zinc fingers from other self antigens (e.g., peptides from Ro60, Ro52, and U1C proteins), and poly(ADP-ribose). Sera from patients with autoimmune rheumatic and bowel diseases were tested, as were affinity-purified antibodies. Histocompatibility typing of systemic lupus erythematosus (SLE) patients was performed by serology. RESULTS: Antibodies from the patient sera reacted only weakly with the recombinant N- and C-terminal domains and with the NLS peptide. In contrast, the 2 synthetic peptides corresponding to zinc-finger motifs F1 and F2 represented immunodominant targets for IgG antibodies from patients with SLE, mixed connective tissue disease (MCTD), Crohn's disease, and ulcerative colitis. The sera from patients with SLE and MCTD showed much weaker reactivity with mutant peptides F1 and F2, which contain mutations at the cysteine residues involved in zinc coordination. F1/F2 antibodies did not cross-react with zinc fingers from other self proteins. No correlation was found between the presence of F1/F2 autoantibodies in SLE sera and the presence of other autoantibodies typical of this disease (e.g., anti-double-stranded DNA and poly[ADP-ribose] antibodies). The presence of F2 antibodies in the serum of SLE patients was negatively associated with HLA-DR6. CONCLUSION: An autoimmune response to PARP is potentially important because this enzyme is involved in DNA repair and is rapidly cleaved during the "execution phase" of apoptosis. The high prevalence in certain autoimmune rheumatic and bowel diseases of antibodies to F1 and F2, which are directly involved in this process, is further evidence implicating involvement of the DNA repair system in chronic inflammatory diseases.

International audience; Autoimmunity is believed to develop when genetically predisposed individuals encounter epigenetic modifications in response to environmental factors. Recent advances in the understanding of epigenetic mechanisms, their contribution to the immune function, and to the development of autoimmunity are presented in this special issue of Clinical Reviews in Allergy and Immunology. Potential new therapeutic strategies and biomarkers are also addressed.