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Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the causative agent of coronavirus disease 2019 (COVID-19), may lead to severe systemic inflammatory response, pulmonary damage, and even acute respiratory distress syndrome (ARDS). This in turn may result in respiratory failure and in death. Experimentally, acetylcholine (ACh) modulates the acute inflammatory response, a neuro-immune mechanism known as the inflammatory reflex. Recent clinical evidence suggest that electrical and chemical stimulation of the inflammatory reflex may reduce the burden of inflammation in chronic inflammatory diseases. Pyridostigmine (PDG), an ACh-esterase inhibitor (i-ACh-e), increases the half-life of endogenous ACh, therefore mimicking the inflammatory reflex. This clinical trial is aimed at evaluating if add-on of PDG leads to a decrease of invasive mechanical ventilation and death among patients with severe COVID-19. Methods A parallel-group, multicenter, randomized, double-blinded, placebo-controlled, phase 2/3 clinical trial to test the efficacy of pyridostigmine bromide 60 mg/day P.O. to reduce the need for invasive mechanical ventilation and mortality in hospitalized patients with severe COVID-19. Discussion This study will provide preliminary evidence of whether or not -by decreasing systemic inflammation- add-on PDG can improve clinical outcomes in patients with severe COVID-19. Trial registration ClinicalTrials.gov NCT04343963 (registered on April 14, 2020).

Background: Regulatory CD4+ T cells (Tregs) exhibit functional alterations in patients with multiple sclerosis (MS). Transforming growth factor (TGF)-β is a key regulator of Treg development and function. Objective: The objective of this study is to determine whether the expression of functionally relevant TGF-β-regulated molecules is altered in Tregs from patients with MS. Methods: Expression of nine Treg markers was analyzed by multi-color flow cytometry in CD4+ T cells and Treg subpopulations of 31 untreated MS patients and age- and sex-matched healthy donors (HDs). Correlations between Treg marker expression and clinical variables were sought. Results: Expression of the transcription factor Helios, which defines thymic-derived Tregs, was decreased in this Treg subpopulation. The frequency of peripherally generated Tregs was increased in patients with MS, particularly in patients with progressive MS. Low frequencies of thymic-derived Tregs were associated with magnetic resonance imaging (MRI) lesion-burden and a high relapse rate. Four surface markers associated with TGF-β signaling (ABCA1, BTLA, DNAM-1, and GARP) were differentially expressed on Tregs from patients with MS and HDs. Expression levels of CD73, CD103, ABCA1, and PAR2 showed strong correlations with disease severity. Conclusion: We have identified novel markers abnormally expressed on Tregs from patients with MS that could detect patients with severe disease.

Chronic inflammation causes target organ damage in patients with systemic autoimmune diseases. The factors that allow this protracted response are poorly understood. We analyzed the transcriptional regulation of PPP2R2B (B55β), a molecule necessary for the termination of the immune response, in patients with autoimmune diseases. Altered expression of B55β conditioned resistance to cytokine withdrawal–induced death (CWID) in patients with autoimmune diseases. The impaired upregulation of B55β was caused by inflammation-driven hypermethylation of specific cytosines located within a regulatory element of PPP2R2B preventing CCCTC-binding factor binding. This phenotype could be induced in healthy T cells by exposure to TNF-α. Our results reveal a gene whose expression is affected by an acquired defect, through an epigenetic mechanism, in the setting of systemic autoimmunity. Because failure to remove activated T cells through CWID could contribute to autoimmune pathology, this mechanism illustrates a vicious cycle through which autoimmune inflammation contributes to its own perpetuation.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease linked to profound defects in the function and phenotype of T lymphocytes. Here, we describe abnormal signaling pathways that have been documented in T cells from patients with SLE and discuss how they impact gene expression and immune function, in order to understand how they contribute to disease development and progression.

Purpose of review The aim of this review is to discuss recent developments in our understanding of how systemic lupus erythematosus (SLE)-associated genes contribute to autoimmunity. Recent findings Gene-function studies have revealed mechanisms through which SLE-associated alleles of IFIH1, TNFAIP3, IRF5, and PRDM1 likely contribute to the development of autoimmunity. Novel research has identified Mac-1 (encoded by ITGAM), CaMK4, and iRhom2 as plausible therapeutic targets in lupus nephritis. Summary The work discussed in this review has broad implications for our understanding of the pathogenesis of SLE and for the development of novel therapeutic strategies.

Disease heterogeneity remains a major challenge for the understanding of systemic lupus erythematosus (SLE). Recent work has revealed the important role of nonimmune factors in the development of end-organ damage involvement, shifting the current paradigm that views SLE as a disease inflicted by a disturbed immune system on passive target organs. Here, we discuss the pathogenesis of lupus nephritis in a comprehensive manner, by incorporating the role that target organs play by withstanding and modulating the local inflammatory response. Moreover, we consider the effects that genetic variants exert on immune and nonimmune cells in order to shape the phenotype of the disease in each affected individual.

The immune-regulatory cytokine IL-10 plays a central role during innate and adaptive immune responses. IL-10 is elevated in the serum and tissues of patients with systemic lupus erythematosus (SLE), an autoimmune disorder characterized by autoantibody production, immune-complex formation, and altered cytokine expression. Because of its B cell-promoting effects, IL-10 may contribute to autoantibody production and tissue damage in SLE. We aimed to determine molecular events governing T cell-derived IL-10 expression in health and disease. We link reduced DNA methylation of the IL10 gene with increased recruitment of Stat family transcription factors. Stat3 and Stat5 recruitment to the IL10 promoter and an intronic enhancer regulate gene expression. Both Stat3 and Stat5 mediate trans-activation and epigenetic remodeling of IL10 through their interaction with the histone acetyltransferase p300. In T cells from SLE patients, activation of Stat3 is increased, resulting in enhanced recruitment to regulatory regions and competitive replacement of Stat5, subsequently promoting IL-10 expression. A complete understanding of the molecular events governing cytokine expression will provide new treatment options in autoimmune disorders, including SLE. The observation that altered activation of Stat3 influences IL-10 expression in T cells from SLE patients offers molecular targets in the search for novel target-directed treatment options.

Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) is a costimulatory receptor in the immunoglobulin superfamily closely related to CD28 and ICOS, and binds to CD80 and CD86 (1;2). Expression of CTLA-4 is constitutive on regulatory T cells (3) and induced following activation on effector T cells (1). It exerts an essential inhibitory role and its absence causes an early and lethal autoimmune disease in mice (4). The CTLA4 gene is highly conserved (76% homology between human and mouse) (5). It is comprised of 4 exons: exon 1 codes for the signal peptide; exon 2 for the ligand-binding domain; exon 3 for the transmembrane region; exon 4 for the intra-cytoplasmic tail (Figure 1A) (6). Human peripheral blood lymphocytes express 3 isoforms of CTLA-4 produced by alternative splicing: full length CTLA-4 (flCTLA-4; all four exons), soluble CTLA-4 (exons 1, 2, and 4), and a short variant that lacks both the ligand-binding domain and the transmembrane domain (1/4 CTLA-4) (6). Allelic variations and single nucleotide polymorphisms in the CTLA4 gene have been associated to several human autoimmune diseases including autoimmune thyroid disease (6), rheumatoid arthritis (7) and systemic lupus erythematosus (SLE) (8;9). Interestingly, the polymorphisms associated with autoimmune disease affect CTLA4 splicing and thus the relative expression of each variant isoform (6). How the differential expression of CTLA-4 isoforms impacts susceptibility to autoimmune disease is not yet clear. Figure 1 The 1/4 CTLA-4 splice variant codes for a secreted protein The 1/4 CTLA-4 isoform lacks the CD80/86-binding domain and the transmembrane portion and thus its function remains unclear. Forced expression of the 1/4 CTLA-4 isoform in T cells was shown to induce spontaneous autoimmune disease and facilitate the development of experimental allergic encephalomyelitis in C57BL/6 mice through an unknown mechanism (10). Here we demonstrate that in lupus-prone mice increased expression of 1/4 CTLA-4 accelerates autoimmunity, exacerbates disease pathology, and causes early mortality.

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with chronic immune activation and tissue damage. Organ damage in SLE results from the deposition of immune complexes and the infiltration of activated T cells into susceptible organs. Cytokines are intimately involved in every step of the SLE pathogenesis. Defective immune regulation and uncontrolled lymphocyte activation, as well as increased antigen presenting cell maturation are all influenced by cytokines. Moreover, expansion of local immune responses as well as tissue infiltration by pathogenic cells is instigated by cytokines. In this review, we describe the main cytokine abnormalities reported in SLE and discuss the mechanisms that drive their aberrant production as well as the pathogenic pathways that their presence promotes.

Objective Systemic lupus erythematosus (SLE) is a chronic inflammatory disease associated with aberrant immune cell function. Treatment involves the use of indiscriminate immunosuppression, which results in significant side effects. SLE T cells express high levels of calcium/calmodulin-dependent protein kinase type IV (CaMKIV), which translocates to the nucleus upon engagement of the T cell receptor–CD3 complex and accounts for abnormal T cell function. The purpose of this study was to determine whether inhibition of CaMKIV would improve disease pathology. Methods We treated MRL/lpr mice with KN-93, a CaMKIV inhibitor, starting at week 8 or week 12 of age and continuing through week 16 and evaluated skin lesions, proteinuria, kidney histopathology, proinflammatory cytokine production, and costimulatory molecule expression. We also determined the effect of silencing of CAMK4 on interferon-γ (IFNγ) expression by human SLE T cells. Results CaMKIV inhibition in MRL/lpr mice resulted in significant suppression of nephritis and skin disease, decreased expression of the costimulatory molecules CD86 and CD80 on B cells, and suppression of IFNγ and tumor necrosis factor α production. In human SLE T cells, silencing of CAMK4 resulted in suppression of IFNγ production. Conclusion We conclude that suppression of CaMKIV mitigates disease development in lupus-prone mice by suppressing cytokine production and costimulatory molecule expression. Specific silencing of CAMK4 in human T cells results in similar suppression of IFNγ production. Our data justify the development of small-molecule CaMKIV inhibitors for the treatment of patients with SLE.

Objective To quantify the expression of CD44 and variant isoforms CD44v3 and CD44v6 on T cells from patients with systemic lupus erythematosus (SLE), and to assess correlations of the level of expression of these molecules with disease manifestations. Methods Information on clinical and demographic characteristics was collected, and blood samples were obtained from 72 patients with SLE and 32 healthy control subjects matched to the patients by sex, race, and age. Expression of CD44 and variants CD44v3 and v6 on T cell subsets was determined by flow cytometry, and Pearson's correlations of their expression levels with clinical variables, SLE Disease Activity Index (SLEDAI) scores, and presence of lupus nephritis were determined. Wilcoxon's rank sum tests and conditional multivariable regression analyses were applied to identify differences in the expression of CD44 between patients with SLE and healthy controls. Results Expression of CD44 was higher on CD4+ and CD8+ T cells from SLE patients compared with controls (P ≤ 0.03). Expression of CD44v3 and CD44v6 was also higher on total T cells and CD4+ and CD8+ T cells from SLE patients compared with controls (P ≤ 0.03). Cell surface levels of CD44v3 on total T cells, CD4+ T cells, and CD8+ T cells as well as cell surface expression of CD44v6 on total T cells and CD4+ T cells were correlated with the SLEDAI score (P < 0.05). The presence of lupus nephritis was associated with the expression of CD44v6 on total T cells, CD4+ T cells, and CD4−CD8− T cells (P < 0.05). Positivity for anti–double-stranded DNA antibodies was associated with the expression levels of CD44v6 on T cells (P < 0.05). Conclusion These results indicate that expression levels of CD44v3 and CD44v6 on T cells may represent useful biomarkers of SLE activity.

Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects women and presents with manifestations derived from the involvement of multiple organs including the kidneys, joints, nervous system, and hematopoietic organs. Immune system aberrations, as well as heritable, hormonal, and environmental factors interplay in the expression of organ damage. Recent contributions from different fields have developed our understanding of SLE and reshaped current pathogenic models. Here, we review novel information that deals with 1) genes associated with disease expression, 2) immune cell molecular abnormalities that lead to autoimmune pathology, 3) the role of hormones and sex chromosomes in the development of disease, 4) environmental and epigenetic factors thought to contribute to the expression of SLE. Finally, we emphasize molecular defects intimately associated with the disease process of SLE that represent ideal therapeutic targets and disease biomarkers.

IL-17 is a cytokine with powerful proinflammatory activity. Production of IL-17 is abnormally increased in patients with systemic lupus erythematosus (SLE), a multiorgan chronic autoimmune disease. In patients with SLE,CD3+CD4−CD8−(double negative) T cells are an important source of IL-17. IL-17 produced by double negative and CD4 T cells participates in the pathogenesis of the disease. IL-17-producing T cells are present in the kidneys of patients with lupus nephritis. IL-17 increased production in patients with SLE can amplify the immune response by increasing target organ inflammation and damage and by augmenting the production of antibodies by B cells.

IL-2 plays a key role in setting the balance between immunity and tolerance. This cytokine has a dual role as the regulator of the two main phases of the immune response (proliferative and suppressive). Likewise, activation induced cell death and the induction and maintenance of regulatory T cells are the tolerance mechanisms regulated by IL-2, which convey the link between IL-2 abnormalities and the development of autoimmune disorders, such as systemic lupus erythematosus (SLE). Particularly, in SLE murine models and in humans, deficiency in IL-2 synthesis and activity has been proven. Diverse signaling pathways abnormalities (TCR, NF-kappaBeta, NF-AT) have been involved in the IL-2 transcriptional dysregulation displayed by T cells from SLE patients, and its functional relevance as part of the physiopathogenic scheme has been shown. Aberrant expression and activity of multiple IL-2 transcriptional factors, such as c-fos, and predominantly, CREM and CREB have been involved in this immune dysregulation. Diverse alterations in signaling kinases and phosphatases (PKA, PP2A, CAMKIV) and the modulation by epigenetic mechanisms have been related to the altered CREM/pCREB index. The synergic effect of multiple abnormalities in the transcriptional factors previously mentioned has been shown to be of functional relevance in lupus.

Multiple elements are known to participate in ischemia/reperfusion (I/R)-mediated tissue injury. Amongst them, B cells have been shown to contribute by the production of antibodies that bind to ischemic cells and fix complement. It is currently unknown whether B cells participate through antibody-independent mechanisms in the pathogenesis of I/R. In a mesenteric I/R model we found that B cells infiltrate the injured intestine of normal and autoimmune mice 2 h after reperfusion is established. B cell depletion protected mice from the development of I/R-mediated intestinal damage. The protection conferred by B cell depletion was significantly greater in MRL/lpr mice. Finally, we show that ischemic tissue expressed the B cell-attractant CXCL13 and infiltrating B cells expressed the corresponding receptor CXCR5. Our data grant B cells an antibody-independent role in the pathogenesis of intestinal I/R and suggest that B cells accumulate in the injured tissue in response to the chemokine CXCL13.

SummaryThe emerging role of interleukin (IL)-17 as a hallmark proinflammatory cytokine of the adaptive immune system, produced primarily by a new T helper cell subset termed ‘Th17’, has received considerable attention. Differentiation of Th17 cells is driven by the simultaneous presence of transforming growth factor-β and certain inflammatory cytokines (e.g. IL-6, IL-21), and recent studies have shown that inflammation instigated by IL-17-producing cells is central to the development and pathogenesis of several human autoimmune diseases and animal models of autoimmunity. In this review, we focus on the information regarding IL-17 and systemic lupus erythematosus (SLE), a chronic autoimmune disease. The work that has explored the development and behaviour of IL-17-producing cells in SLE is discussed, and different mechanisms by which IL-17 could potentially augment inflammation and autoantibody production in the context of SLE are proposed.

Double negative (DN) T cells are expanded in patients with systemic lupus erythematosus (SLE) and stimulate autoantibody production as efficiently as CD4+ T cells. In this study, we demonstrate that DN T cells from patients with SLE produce significant amounts of IL-17 and IFN-γ, and expand when stimulated in vitro with an anti-CD3 Ab in the presence of accessory cells. Furthermore, IL-17+ and DN T cells are found in kidney biopsies of patients with lupus nephritis. Our findings establish that DN T cells produce the inflammatory cytokines IL-17 and IFN-γ, and suggest that they contribute to the pathogenesis of kidney damage in patients with SLE.

T cells from patients with systemic lupus erythematosus (SLE) display a number of biochemical abnormalities which include altered expression of key signaling molecules, heightened calcium responses, and skewed expression of transcription factors. These defects are involved in the altered behavior of SLE T cells and are probably central in the disease pathogenesis. The aim of this communication is to review the defects that have been consistently documented in SLE T cells, highlighting molecules and pathways that represent therapeutic targets.

T cells contribute to the pathogenesis of systemic lupus erythematosus (SLE) as central elements during the loss of tolerance, the perpetuation of the autoimmune response, and by directly instigating inflammation in target organs. Their pathogenic behavior is driven by an abnormal gene expression profile that results from changes in signaling pathways, transcription factor activity, and a grossly altered epigenetic landscape. Here, we describe the signaling and genetic aberrations that make SLE T cells pathogenic and discuss the various mechanisms through which they drive pathology in lupus.

Inducible cAMP early repressor (ICER) has been described as a transcriptional repressor isoform of the cAMP response element modulator (CREM). Here we report that ICER is predominantly expressed in Th17 cells through the IL-6–STAT3 pathway and binds to the Il17a promoter, where it facilitates the accumulation of the canonical enhancer RORγt. In vitro differentiation from naive ICER/CREM-deficient CD4+ T cells to Th17 cells is impaired but can be rescued by forced overexpression of ICER. Consistent with a role of Th17 cells in autoimmune and inflammatory diseases, ICER/CREM-deficient B6.lpr mice are protected from developing autoimmunity. Similarly, both anti-glomerular basement membrane-induced glomerulonephritis and experimental encephalomyelitis are attenuated in ICER/CREM-deficient mice compared with their ICER/CREM-sufficient littermates. Importantly, we find ICER overexpressed in CD4+ T cells from patients with systemic lupus erythematosus. Collectively, our findings identify a unique role for ICER, which affects both organ-specific and systemic autoimmunity in a Th17-dependent manner., ICER is a CREM splice variant that represses CREM/CREB signalling. Here the authors use human cells and mouse models of various autoimmune diseases to show that ICER is central to pathogenic Th17 cell differentiation in autoimmunity.

Homeostasis of the immune system depends on the proper function of regulatory T cells (T(reg) cells). Compromised suppressive activity of T(reg) cells leads to autoimmune disease and graft rejection and promotes anti-tumor immunity. Here we report a previously unrecognized requirement for the serine-threonine phosphatase PP2A in the function of T(reg) cells. T(reg) cells exhibited high PP2A activity, and T(reg) cell-specific ablation of the PP2A complex resulted in a severe, multi-organ, lymphoproliferative autoimmune disorder. Mass spectrometry revealed that PP2A associated with components of the mTOR metabolic-checkpoint kinase pathway and suppressed the activity of the mTORC1 complex. In the absence of PP2A, T(reg) cells altered their metabolic and cytokine profile and were unable to suppress effector immune responses. Therefore, PP2A is required for the function of T(reg) cells and the prevention of autoimmunity.

Behcet’s disease is a multi-system inflammatory disorder of unknown etiology. The disease is more prevalent in Eastern Mediterranean countries and Japan where there is a linkage to HLA-B51. Mexican Mestizos are suitable subjects for studying the role of ethnicity in the susceptibility to Behcet’s disease. High-resolution HLA class I and class II typing was performed by polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) reverse dot blot and PCR-single-strand polymorphism in 32 patients with Behcet’s disease and 99 healthy ethnically-matched controls. A significant increased frequency of HLA-B * 44 ( P =0.02; OR = 2.78; CI 95% = 1.1–7.7), HLA-B * 52 ( P =0.02; OR = 5.33; CI 95% = 1.07–29.1), and HLA-B * 56 ( P =0.003; OR = 4.19; CI 95% = 3.37–5.21) as well as HLA-DRB1 * 01 and HLA-DRB1 * 13 ( P =0.007; OR = 3.36; CI 95% = 1.22–9.27) was found in Mexican patients with Behcet’s disease when compared to controls. The low frequency of native markers in Mexican Mestizo patients with Behcet’s disease suggests that genetic admixture between Eastern Mediterraneans and Orientals with Amerindians is a recent event that increased the risk of developing Behcet’s disease in the Mexican population.

CD4+ T cells that constitutively express CD25 exhibit powerful suppressive properties. Such cells have been denominated regulatory T cells (T(R)). Alterations in T(R)cells are known to cause organ-specific autoimmune disease in animal models. The aim of this work was to quantify CD4+CD25+ T cells in patients with systemic lupus erythematosus (SLE). Thirty untreated patients (ten with active disease) and ten healthy volunteers were studied. Flow cytometry was used to quantify cell populations. CD4+CD69+, CD4+CD25+ and CD4+CD25(bright) cells were considered. Peripheral blood mononuclear cell cultures were performed and supernatants collected for IL-10 and 12 measurement. CD4+CD25+ cells were significantly decreased in patients with active disease when compared to control subjects and patients without disease activity (P

Diabetes mellitus has been linked to disorders of bones and joints, including neuroarthropathy, limited joint mobility, and hyperostosis. Some of the relations have known pathogenic mechanisms, but most are based on epidemiologic findings. This article reviews the associations between diabetes mellitus and its putative rheumatologic manifestations, and proposes a classification composed of four categories: consequences of diabetic complications, consequences of metabolic derangements inherent to diabetes, syndromes that may share etiologic mechanisms with microvascular disease, and probable associations. This approach may facilitate a clearer understanding of the musculoskeletal conditions that are prevalent in patients with diabetes mellitus.

Little is known about the immune system of patients with systemic lupus erythematosus(SLE) during periods of silent disease. To address this issue we analysed lymphoid populations and cytokine productionof mononuclearcells obtained from SLE patients in remission.We studied 43 patients with inactive disease, 10 with active disease and 30 controls. Remission was defined as at least 1 year during which lack of clinical disease activity permitted withdrawal of all treatment. Remission length ranged from 1 to 30 years. Flow cytometry and ELISA were used to study lymphoid populations (CD4, CD8 and CD19) and cytokineproduction(IL-2, 4, 10, 12 and 18). Patientswith short remission periods (up to 15 years) exhibited an increased percentage of B cells; production of IL-2, IL-10 and IL-12 was decreased;productionof IL-18 was increased. Interestingly, patients from groups with long time of inactive disease had corrected most alterations, but had an impaired IL-18 expression. IL-12 production correlated strongly with the length of the remission period (r 0.7565). The immune system of patients with inactive lupus has partially corrected the disturbances present during disease activity.This is accomplishedgradually, sometimes until counter-regulatoryalterationsare developed. This may allow patients to remain without disease activity.

Complement activation takes place in autoimmune diseases and accounts for tissue inflammation. Previously, complement inhibition has been considered for the treatment of SLE. Complement receptor of the immunoglobulin superfamily (CRIg) is a selective inhibitor of the alternative pathway of complement and a soluble form reverses established inflammation and bone destruction in experimental autoimmune arthritis. We asked whether specific inhibition of the alternative pathway could inhibit autoimmunity and/or organ damage in lupus-prone mice. Accordingly, we treated lupus-prone MRL/lpr mice with a soluble form of CRIg (CRIg-Fc) and we found that it significantly diminished skin lesions, proteinuria and pyuria, and kidney pathology. Interestingly, serum levels of anti-DNA antibodies were not affected despite the fact that serum complement 3 (C3) levels increased significantly. Immunofluorescent staining of kidney tissues revealed a reduction in staining intensity for C3, IgG, and the macrophage marker Mac-2. Thus our data show that inhibition of the alternative pathway of complement controls skin and kidney inflammation even in the absence of an effect on the production of autoantibodies. We propose that CRIg should be considered for clinical trials in patients with systemic lupus erythematosus.

Epigenetic events play a central role in the priming, differentiation and subset determination of T lymphocytes. Through their influence on chromatin conformation and DNA-accessibility to transcription factors and RNA polymerases, epigenetic marks allow or prevent gene expression and control cellular functions including cytokine expression. CpG-DNA methylation and post-translational modifications to histone tails are the two most well accepted epigenetic mechanisms. The involvement of epigenetic mechanisms in the pathogenesis of systemic lupus erythematosus (SLE) has been suggested by the development of lupus-like symptoms by individuals who received procainamide or hydralazine treatment resulting in a reduction of CpG-DNA methylation. To date, a growing body of literature indicates that the deregulation of cytokine expression through epigenetic disturbances can result in altered immune responses and autoimmune reactions. Over the past decade, various global and regional epigenetic alterations have been reported in immune cells from patients with SLE and other autoimmune disorders. More recently, the molecular mechanisms that result in epigenetic disturbances have been addressed, and deregulated transcription factor networks have been demonstrated to mediate epigenetic alterations in B and T lymphocytes from SLE patients. A better understanding of the molecular events that contribute to epigenetic alterations and subsequent immune imbalance is essential for the establishment of disease biomarkers and identification of potential therapeutic targets.

Systemic lupus erythematosus (SLE) is a highly heterogeneous disorder in which multiple immunologic abnormalities have been described. In this review, we thoroughly analyse the impaired T cell production of, and response to, interleukin-2 (IL-2) characteristic of patients with SLE. Since it was first reported, several articles have provided us with enlightening, but somewhat confusing, data that reveal the complexity of the subject. The IL-2 production by T cells is part of a complex network in which a discrete alteration is capable of disrupting the whole system. On the other hand, regulatory mechanisms exist that, in an attempt to compensate the primary alteration, provoke secondary defects. Evidence indicates that this defect is not intrinsic, but rather, results from multiple microenvironmental influences that act on the T cell and modify its activation state and its cytokine production. Abnormalities in co-stimulatory mechanisms and in cytokines that may be related to the IL-2 production deficiency, have been described in patients with SLE. We also consider the information derived from murine SLE models, IL-2 knockout models and reports concerning the immune dysregulation present in patients with SLE.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown etiology. It affects mostly women in their child-bearing years. In SLE, the immune system attacks multiple organs including the kidneys, joints, skin, and nervous system among others and thus, SLE manifestations correspond to the combination of organs targeted in every patient. Genetic, epigenetic, and environmental factors all contribute to the pathogenesis of SLE and both the innate and adaptive arm of the immune system is involved in the development of this autoimmune disease. With the orchestrated action of T cells, B cells, dendritic cells, monocytes, and neutrophils, immune self-tolerance is lost in patients with SLE and tissue damage and destruction ensues.

The aetiology of systemic lupus erythematosus (SLE) is complex and is known to involve both genetic and environmental factors. In a small number of patients, single-gene defects can lead to the development of SLE. Such genes include those encoding early components of the complement cascade and the 3'-5' DNA exonuclease TREX1. In addition, genome-wide association studies have identified single-nucleotide polymorphisms that confer some susceptibility to SLE. In this Review, we discuss selected examples of genes whose products have distinctly altered function in SLE and contribute to the pathogenic process. Specifically, we focus on the genes encoding integrin αM (ITGAM), IgG Fc receptors, sialic acid O-acetyl esterase (SIAE), the catalytic subunit of protein phosphatase PP2A (PPP2CA) and signalling lymphocytic activation molecule (SLAM) family members. Moreover, we highlight the changes in epigenetic signatures that occur in SLE. Such epigenetic modifications, which are abundantly present and might alter gene expression in the presence or absence of susceptibility variants, should be carefully considered when deconstructing the contribution of individual genes to the complex pathogenesis of SLE.

The activity of calcium/calmodulin-dependent protein kinase IV (CaMK4) is increased in T cells from patients with systemic lupus erythematosus (SLE) and has been shown to reduce IL-2 production by promoting the effect of the transcriptional repressor cAMP responsive element modulator-α on the IL2 promoter. In this article, we demonstrate that T cells from MRL/lpr mice display increased levels of CaMK4 in the nucleus, and that genetic deletion of Camk4 results in improved survival. We demonstrate that absence of CaMK4 restores IL-2 production, curbs increased T cell activation, and augments the number and activity of regulatory T cells. Analogously, silencing of CaMK4 in T cells from patients with SLE increases the expression of FoxP3 on stimulation in the presence of TGF-β. Our results demonstrate the importance of the serine/threonine kinase CaMK4 in the generation and function of regulatory T cells in patients with SLE and lupus-prone mice, and its potential to serve as a therapeutic target.

The contribution of individual molecular aberrations to the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease that affects multiple organs, is often difficult to evaluate because of the presence of abundant confounding factors. To assess the effect of increased expression of the phosphatase protein phosphatase 2A (PP2A) in T cells, as recorded in SLE patients, we generated a transgenic mouse that overexpresses the PP2Ac subunit in T cells. The transgenic mouse displays a heightened susceptibility to immune-mediated glomerulonephritis in the absence of other immune defects. CD4+ T cells produce increased amounts of IL-17 while the number of neutrophils in the peripheral blood is increased. IL-17 neutralization abrogated the development of glomerulonephritis. We conclude that increased PP2Ac expression participates in SLE pathogenesis by promoting inflammation through unchecked IL-17 production and facilitating the development of end-organ damage.

The activity and substrate specificity of the ubiquitously expressed phosphatase PP2A is determined by the type of regulatory (B) subunit that couples to the catalytic/scaffold core of the enzyme. We determined that the Bβ subunit ( PPP2R2B ) is expressed in resting T cells, its transcription is down-regulated during T-cell activation, and up-regulated in conditions of low IL-2. Specifically, high levels of PP2A Bβ were produced during IL-2 deprivation-induced apoptosis, whereas Fas ligation had no effect. Forced expression of the Bβ subunit in primary human T cells was sufficient to induce apoptosis, whereas silencing using siRNA protected activated T cells from IL-2 withdrawal-induced cell death. Because T-cell apoptosis is known to be altered in T cells from patients with systemic lupus erythematosus, we analyzed the regulation of PP2A Bβ in this autoimmune disease. We found that levels of PP2A Bβ did not increase upon IL-2 deprivation in 50% of the patients. Remarkably, this defect was accompanied by resistance to apoptosis. Importantly, kinetics of cell death were normal in cells of patients that up-regulated PP2A Bβ in a normal manner. We have identified a unique role for the phosphatase PP2A, particularly the holoenzyme formed by PP2A Bβ. Bβ appears to trigger apoptosis of T cells in the absence of IL-2 and probably contributes to the termination of a no-longer-needed immune response. We propose that defective production of PP2A Bβ upon IL-2 deprivation results in apoptosis resistance and longer survival of autoreactive T cells, in a subset of SLE patients.

Significant evidence implicates interleukin-17 (IL-17) in the pathogenesis of systemic lupus erythematosus (SLE), particularly in the development of tissue damage. IL-17 production and IL-17-producing CD4+ and CD3 + CD4−CD8− cells are increased in patients with SLE. IL-17-producing cells are present in the inflamed kidney tissues from patients with lupus nephritis. In lupus-prone mice, IL-17 production appears to be involved in the expression of disease pathology and pharmacologic or genetic manipulation of its production results in suppression of the disease. It becomes obvious that the use of biologics including humanized anti-IL-17 antibodies or decoy IL-17 receptors deserve clinical consideration. Similarly, the development of drugs that suppress the production of IL-17 is in order.

Summary Lymphopenia is a common clinical manifestation in patients with systemic lupus erythematosus (SLE). However, its physiopathogenic role and the contribution of different T cell subsets in this setting have not been addressed fully. The aim of this study was to characterize T cell subsets quantitatively and functionally and their association with lymphopenia and azathioprine treatment in SLE. We included 84 SLE patients and 84 healthy controls and selected 20 patients for a 6-month longitudinal analysis. Peripheral blood mononuclear cells were isolated, and T cell subsets were analysed by flow cytometry. Functional analyses included autologous and allogeneic co-cultures of T cells. Our data show persistently lower absolute numbers of CD4+CD25high T cells [regulatory T cells (Tregs)] (1·9 versus 5·2, P

Altered cytokine production has long been recognized to be involved in the immune pathogenesis of systemic lupus erythematosus (SLE). Interleukin 17 (IL-17) has recently been recognized as a contribution to the advancement of the auto-immune response and the expression of tissue injury. Increased production of IL-17 has been documented in humans with SLE and therefore validated its contribution to increased auto-antibody production and kidney inflammation. However, suppression of IL-17 production in lupus-prone mice results in disease improvement.

Purpose of review Interleukin-17 (IL-17) has emerged as a key cytokine involved in the pathogenesis of autoimmune diseases. In this article, we review recently produced evidence obtained in patients and murine models of lupus that link increased IL-17 production with lupus pathology and discuss the potential roles IL-17 may play in the pathogenesis of systemic lupus erythematosus. Recent findings IL-17 may promote autoantibody production and IL-1 7-producing cells are found in afflicted organs in humans and lupus-prone mice. T H 17 and CD3 + CD4 - CD8 - cells are expanded in systemic lupus erythematosus patients and account for the increased production of IL-17. Genetic silencing of genes involved in the increased production of IL-17 in lupus-prone mice as well as treatment of mice with lupus using biologic agents that result in decreased IL-17 production leads invariably to disease mitigation. Summary The presented evidence strongly argues for the introduction of IL-17-suppressing biologics in the treatment of patients with systemic lupus erythematosus.

Elements of the innate and adaptive immune response have been implicated in the development of tissue damage after ischemic reperfusion (I/R). Here we demonstrate that T cells infiltrate the intestine of C57BL/6 mice subjected to intestinal I/R during the first hour of reperfusion. The intensity of the T cell infiltration was higher in B6.MRL/lpr mice subjected to intestinal I/R and reflected more severe tissue damage than that observed in control mice. Depletion of T cells limited I/R damage in B6.MRL/lpr mice, whereas repletion of B6.MRL/lpr lymph node-derived T cells into the I/R-resistant Rag-1−/− mouse reconstituted tissue injury. The tissue-infiltrating T cells were found to produce IL-17. Finally, IL-23 deficient mice, which are known not to produce IL-17, displayed significantly less intestinal damage when subjected to I/R. Our data assign T cells a major role in intestinal I/R damage by virtue of producing the pro-inflammatory cytokine IL-17.

We discuss a 53-year-old woman with systemic lupus erythematosus who presented with vasculitis, hypocomplementemia and nephritis. Although her serum complement 4 (C4) levels were zero, she had four copies of C4 gene. Renal biopsy revealed membranoproliferative glomerulonephritis and the presence of cryoglobulins, detected by electron microscopy, and significant numbers of T cells in the interstitium. Cryoglobulins were considered responsible for the complete consumption of C4 in the serum the levels of which improved gradually after treatment. T cells in the kidney were found to express CD44 and phosphorylated ezrin/radixin/moiesin which explain why they homed to the kidney inappropriately. The contribution of cryoglobulins and T cells in the expression of kidney pathology is discussed.

T cells from patients with systemic lupus erythematosus exhibit a notable array of defects that probably contribute to the origin and development of the disease. Such abnormalities include an abnormal response to stimulation, aberrant expression of molecules that play key roles in intracellular signalling pathways, altered transcription factor activation and binding, and skewed gene expression. The combination of these alterations leads the cell to the expression of a particular phenotype that intense research has gradually uncovered over the last years. The aim of this article is to review the findings that have allowed us to better understand the behaviour of the lupus T cell and highlight the molecules that represent potential therapeutic targets.

T cells from patients with systemic lupus erythematosus (SLE) exhibit several discrete and specific defects that alter signaling pathways and, thus, the gene expression pattern and behavior upon stimulation. Rewiring of the CD3 complex and aggregation of surface-membrane lipid rafts grant SLE T cells a lower activation threshold and distort the ensuing signaling events. Additionally, increased expression of adhesion molecules within aggregated lipid rafts guides them to target organs. Aberrant cell signaling causes altered transcription factor expression and abnormal DNA-methylation patterns that lead to skewed gene expression. The result is an abnormally functioning T cell that exhibits several molecular alterations that can be exploited as therapeutic or diagnostic markers.

Dendritic cells (DC) play a pivotal role in the development of immune responses and the maintenance of peripheral tolerance. They continuously patrol tissues and sample antigens in search for the presence of inflammatory or pathogen-derived signals; they mature in accordance to signs prevalent in their environment and, by doing so, acquire certain features that will allow them to convey a precise message — either productive or regulatory — to the T cells they will encounter within regional lymph nodes. Evidence suggests that DC are involved in the pathogenesis of SLE. Their capacity to induce an antinuclear-oriented autoimmune response has been proven in animal models. Further, their maturation process is abnormal and their cytokine secretion and T cell stimulation is biased in patients with SLE. Lupus, however, is a problematic environment for their study and characterization. Sera from SLE patients contain several factors capable of inducing phenotypic and functional changes in DC. Thus, the abnormalities that have been reported may represent DC-intrinsic defects, a skewed phenotype due to an abnormal milieu, or a combination of both. In this review we discuss the available information in an attempt to reconcile these issues.

Background IL-17 producing T helper (Th17) cells have been closely associated with the development of organ damage in inflammatory and autoimmune diseases. We have previously reported that Calcium/calmodulin-dependent protein kinase IV (CaMK4) plays a crucial role in Th17 cell differentiation invitro and invivo and suggested that CaMK4 inhibition ameliorates clinical and pathological findings in experimental autoimmune encephalomyelitis (EAE) and MRL/lpr mice (1). We have also shown that Il-17 is important in the expression of anti-glomerular basement membrane Ab-induced glomerulonephritis (AIGN) (2). However, the effect of CaMK4 on recruitment of pathogenic T cells to target tissues in inflammatory settings has not been studied. Objectives The aim of this study is to determine the role of CaMK4 in the infiltration of inflammatory cells to target tissues and to explore its mechanism. Methods We induced experimental AIGN in Camk4 sufficient or deficient mice and compared the kidney injury including the number of IL-17 producing cells and the expression of CCR6 and CCL20 in both groups. We also evaluated the effect of KN-93, a compound of CaMK4 antagonist in this AIGN model. Results Camk4 deficient mice displayed less glomerular injury and less proteinuria at day 14 and at day 21 after induction of AIGN. The expression of CCR6 and CCL20 in inflamed kidney is lower in Camk4 deficient mice. Kidney infiltration by Th17 producing CD4+ T cells was decreased significantly in Camk4 deficient mice, suggesting that CaMK4 facilitated AIGN damage by promoting local inflammatory cells accumulation. In line with these observations, KN-93 treatment improved clinical and pathological finings in mice induced AIGN at dose dependent manner. Conclusions Collectively, our results indicate that CaMK4 inhibition might be a novel therapeutic strategy of Th17 cells-mediated inflammatory diseases. References CaMK4-dependent activation of AKT/mTOR and CREM-α underlies autoimmunity-associated Th17 imbalance. Koga T, Hedrich CM, Mizui M, Yoshida N, Otomo K, Lieberman LA, Rauen T, Crispin JC, Tsokos GC. J Clin Invest. 2014 May 1;124(5):2234-45. Cutting edge: protein phosphatase 2A confers susceptibility to autoimmune disease through an IL-17-dependent mechanism.Crispin JC, Apostolidis SA, Rosetti F, Keszei M, Wang N, Terhorst C, Mayadas TN, Tsokos GC.J Immunol. 2012 Apr 15;188(8):3567-71. Disclosure of Interest None declared

We describe the case of a young woman with systemic lupus erythematosus (SLE) who presented with painful acute swelling and limited motion of the elbow. Analysis of synovial fluid exhibited a noninflammatory cell count, negative cultures, amorphous nonbirefringent particles, and a positive Alizarin red S staining. X-rays showed calcifications, spurring, sclerosis, and despite the short duration of symptoms, loss of radial-humeral and cubital-humeral joint spaces. The diagnosis of an acute attack within a chronic degenerative arthropathy of the elbow associated with hydroxyapatite crystals was established. Such crystal-induced arthropathy can be an occasional explanation for acute arthritis in SLE.

Objectives. Neutropenia is an uncommon albeit relevant finding in patients with systemic lupus erythematosus (SLE). It has been ascribed to several aetiologies and represents a challenging dilemma in which clinical findings, laboratory data and medication history must be carefully evaluated. The aim of this work was to review the cases of moderate and severe neutropenia in our cohort of SLE patients in order to identify predisposing factors, clinical outcomes and related prognostic implications. Methods. Thirty-three cases of neutropenia (neutrophil count

We conducted the current study to evaluate the cases of fever of unknown origin (FUO) admitted in our institution during the 10 years between 1991 and 2001 and to compare the patients diagnosed as having adult-onset Still disease (AOSD) with the patients with FUO due to other diagnoses. We performed a case-control study and analyzed 26 patients with AOSD and 135 patients with FUO due to other diseases. Controls were classified into 1 of 4 groups: 1. Infectious diseases; 2. Malignant conditions; 3. Autoimmune diseases; 4. No diagnosis. Differences between groups were evaluated by analysis of variance (ANOVA). Odds ratios (OR) were calculated by multiple logistic regression analyses. Patients with AOSD were younger than controls. Arthritis (OR, 8.6; 95% confidence interval [CI], 1.5-49.1; p = 0.014), pharyngitis (OR, 6.9; 95% CI, 1.5-30.2; p = 0.010), splenomegaly (OR, 5.4; 95% CI, 1.1-26.7; p = 0.039), and neutrophilic leukocytosis (OR, 18.1; 95% CI, 3.5-93.6; p = 0.001) were significantly more common in patients with AOSD than in the control groups. A clinical scale that identifies patients with AOSD was designed. It proved to be highly specific ( approximately 98%), with predictive values greater than 90%.AOSD is a defined clinical entity. In most cases, it is clinically distinguishable from other causes of FUO. We propose a clinical scale as a tool to identify patients whose disease can be diagnosed based on clinical grounds without the need of long, costly diagnostic procedures.

Previously it was shown that the TNF superfamily member TWEAK (TNFSF12) acts through its receptor, Fn14, to promote proinflammatory responses in kidney cells, including the production of MCP-1, RANTES, IP-10 and KC. In addition, the TWEAK/Fn14 pathway promotes mesangial cell proliferation, vascular cell activation, and renal cell death. To study the relevance of the TWEAK/Fn14 pathway in the pathogenesis of antibody-induced nephritis using the mouse model of nephrotoxic serum nephritis (NTN), we induced NTN by passive transfer of rabbit anti-glomerular antibodies into Fn14 knockout (KO) and wild type (WT) mice. Severe proteinuria as well as renal histopathology were induced in WT but not in Fn14 KO mice. Similarly, a pharmacologic approach of anti-TWEAK mAb administration into WT mice in the NTN model significantly ameliorated proteinuria and improved kidney histology. Anti-TWEAK treatment did not affect the generation of mouse anti-rabbit antibodies; however, within the kidney there was a significant decrease in glomerular immunoglobulin deposition, as well as macrophage infiltrates and tubulointerstitial fibrosis. The mechanism of action is most likely due to reductions in downstream targets of TWEAK/Fn14 signaling, including reduced renal expression of MCP-1, VCAM-1, IP-10, RANTES as well as Fn14 itself, and other molecular pathways associated with fibrosis in anti-TWEAK treated mice. Thus, TWEAK/Fn14 interactions are instrumental in the pathogenesis of nephritis in the NTN model, apparently mediating a cascade of pathologic events locally in the kidney rather than by impacting the systemic immune response. Disrupting TWEAK/Fn14 interactions may be an innovative kidney-protective approach for the treatment of lupus nephritis and other antibody-induced renal diseases.

Background Autoimmune diseases such as systemic lupus erythematosus (SLE) display quantitative (1) and/or qualitative (2) deficiencies of Foxp3+ regulatory T (Treg) cells and this is considered to contribute to immune dysregulation and organ damage (3). Calcium/calmodulin-dependent protein kinase IV (CaMK4) is expressed at increased levels in T cells from SLE patients (4) and lupus-prone mice (5). Objectives Treg are pivotal for the maintenance of peripheral tolerance and prevent development of autoimmune diseases. We have reported that CaMK4 deficient MRL/ lpr mice display less disease activity by promoting IL-2 production and increasing the activity of Treg cells. To further define the mechanism of CaMK4 on Treg cells in SLE, we used the Foxp3 -GFP reporter mice and treated them with KN-93, an inhibitor of CaMK4. Methods We generated MRL/ lpr Foxp3- GFP mice to record Treg cells; stimulated naive CD4+ T cells from MRL/ lpr Foxp3- GFP mice under Treg polarizing conditions in the absence or presence of KN-93; evaluated the number of GFP` positive cells in lymphoid organs and examined skin and kidney pathology at 16 week of age. We also examined the infiltration of cells and recruitment of Treg cells in the kidney. Results We show that culture of MRL/ lpr Foxp3- GFP T cells in the presence of KN-93 promotes Treg differentiation in a dose dependent manner (Fig. F). Treatment of MRL/ lpr Foxp3- GFP mice with KN-93 results in significant induction of Treg cells in the spleen, peripheral lymph nodes (Fig. B-E) and peripheral blood (Fig. A and B) and this is accompanied by decreased skin and kidney damage. Notably, KN-93 clearly diminishes the accumulation of inflammatory cells along with reciprocally increased Treg cells in target organ. ![Figure 1][1] Figure 1 Conclusions Our results indicate that KN-93 treatment enhances the generation of Treg cells in vitro and in vivo highlighting its potential therapeutic use for the treatment of human autoimmune diseases. References 1. Valencia X, Yarboro C, Illei G, Lipsky PE. Deficient CD4+CD25high T regulatory cell function in patients with active systemic lupus erythematosus. J Immunol. 2007;178(4):2579-88. 2. Yan B, Ye S, Chen G, Kuang M, Shen N, Chen S. Dysfunctional CD4+,CD25+ regulatory T cells in untreated active systemic lupus erythematosus secondary to interferon-alpha-producing antigen-presenting cells. Arthritis Rheum. 2008;58(3):801-12. 3. Shevach EM. Mechanisms of foxp3+ T regulatory cell-mediated suppression. Immunity. 2009;30(5):636-45. 4. Juang YT, Wang Y, Solomou EE, Li Y, Mawrin C, Tenbrock K, et al. Systemic lupus erythematosus serum IgG increases CREM binding to the IL-2 promoter and suppresses IL-2 production through CaMKIV. J Clin Invest. 2005;115(4):996-1005. 5. Koga T, Ichinose K, Mizui M, Crispin JC, Tsokos GC. Calcium/Calmodulin-Dependent Protein Kinase IV Suppresses IL-2 Production and Regulatory T Cell Activity in Lupus. J Immunol. 2012;189(7):3490-6. Acknowledgements This work was supported by NIH grants RO1 AI R01AI085567 and AR064350. Disclosure of Interest : None declared DOI 10.1136/annrheumdis-2014-eular.2491 [1]: pending:yes