Altered pattern of TCR/CD3-mediated protein-tyrosyl phosphorylation in T cells from patients with systemic lupus erythematosus. Deficient expression of the T cell receptor zeta chain

KLF13 promotes SLE pathogenesis by modifying chromatin accessibility of key proinflammatory cytokine genes

Although significant progress has been achieved in elucidating the genetic architecture of systemic lupus erythematosus (SLE), identifying genes underlying the pathogenesis has been challenging. The NZM2410-derived lupus susceptibility Sle3 locus is associated with T cell hyperactivity and activated myeloid cells. However, candidate genes associated with these phenotypes have not been identified. Here, we narrow the Sle3 locus to a smaller genomic segment (Sle3k) and show that mice carrying Sle3k and Sle1 loci developed lupus nephritis. We identify Klf13 as the primary candidate gene that is associated with genome-wide transcription changes resulting in higher levels of proinflammatory cytokines, enhanced T cell activation, and hyperresponsiveness of myeloid cells. Correspondingly, Klf13 -/- mice display repression of genes involved in mediating immune activation, including key proinflammatory cytokines/chemokines in T cells and dysregulation in cytokine signaling pathways in myeloid cells in response to toll receptor ligands. Klf13 upregulation is associated with increased production of RANTES, a key chemokine in lupus nephritis, in activated T cells and the kidneys of lupus-prone mice. In sum, our findings reveal Klf13 as a key gene in the Sle3 interval in mediating lupus pathogenesis that may have implications in the rational design of new therapies for SLE.

Autoimmune diseases and atherosclerotic cardiovascular disease

Autoimmune diseases are associated with a dramatically increased risk of atherosclerotic cardiovascular disease and its clinical manifestations. The increased risk is consistent with the notion that atherogenesis is modulated by both protective and disease-promoting immune mechanisms. Notably, traditional cardiovascular risk factors such as dyslipidaemia and hypertension alone do not explain the increased risk of cardiovascular disease associated with autoimmune diseases. Several mechanisms have been implicated in mediating the autoimmunity-associated cardiovascular risk, either directly or by modulating the effect of other risk factors in a complex interplay. Aberrant leukocyte function and pro-inflammatory cytokines are central to both disease entities, resulting in vascular dysfunction, impaired resolution of inflammation and promotion of chronic inflammation. Similarly, loss of tolerance to self-antigens and the generation of autoantibodies are key features of autoimmunity but are also implicated in the maladaptive inflammatory response during atherosclerotic cardiovascular disease. Therefore, immunomodulatory therapies are potential efficacious interventions to directly reduce the risk of cardiovascular disease, and biomarkers of autoimmune disease activity could be relevant tools to stratify patients with autoimmunity according to their cardiovascular risk. In this Review, we discuss the pathophysiological aspects of the increased cardiovascular risk associated with autoimmunity and highlight the many open questions that need to be answered to develop novel therapies that specifically address this unmet clinical need.

Circ-CAMTA1 regulated by Ca2+ influx inhibited pyruvate carboxylase activity and modulate T cell function in patients with systemic lupus erythematosus

OBJECTIVES

To investigate the roles of Ca2+ influx-regulated circular RNAs (circRNAs) in T cells from patients with systemic lupus erythematosus (SLE).

METHODS

The expression profile of circRNAs in Jurkat cells, co-cultured with and without ionomycin, was analyzed by next-generation sequencing and validated using real-time polymerase chain reaction. The identified Ca2+ influx-regulated circRNAs were further examined in T cells from 42 patients with SLE and 23 healthy controls. The biological function of specific circRNA was investigated using transfection and RNA pull-down assay.

RESULTS

After validation, we confirmed that the expression levels of circ-ERCC4, circ-NFATC2, circ-MYH10, circ-CAMTA1, circ-ASH1L, circ-SOCS7, and circ-ASAP1 were consistently increased in Jurkat cells following Ca2+ influx. The expression levels of circ-CAMTA1, circ-ASH1L, and circ-ASAP1 were significantly lower in T cells from patients with SLE, with even lower levels observed in those with higher disease activity. Interferon (IFN)-α was found to suppress the expression of circ-CAMTA1. Circ-CAMTA1 bound to pyruvate carboxylase and inhibited its biological activity. Overexpression of circ-CAMTA1, but not its linear form, significantly decreased extracellular glucose levels. Furthermore, increased expression of circ-CAMTA1, but not its linear form, decreased miR-181c-5p expression, resulting increased IL-2 secretion.

CONCLUSION

Three Ca2+ influx-regulated circ-RNAs-circ-CAMTA1, circ-ASH1L, and circ-ASAP1 -were significantly reduced in T cells from patients with SLE and associated with disease activity. IFN-α suppressed the expression of circ-CAMTA1, which interacted with pyruvate carboxylase, inhibited its activity, affected glucose metabolism, and increased IL-2 secretion. These findings suggest that circ-CAMTA1 regulated by Ca²⁺ influx modulated T cell function in patients with SLE.

CD38 in SLE CD4 T cells promotes Ca2+ flux and suppresses interleukin-2 production by enhancing the expression of GM2 on the surface membrane

CD38 has emerged as a potential therapeutic target for patients with systemic lupus erythematosus (SLE) but it is not known whether CD38 alters CD4+ T cell function. Using primary human T cells and CD38-sufficient and CD38-deficient Jurkat T cells, we demonstrate that CD38 shifts the T cell lipid profile of gangliosides from GM3 to GM2 by upregulating B4GALNT1 in a Sirtuin 1-dependent manner. Enhanced expression of GM2 causes ER stress by enhancing Ca2+ flux through the PLCγ1-IP3 pathway. Interestingly, correction of the calcium overload by an IP3 receptor inhibitor, but not by a store-operated calcium entry (SOCE) inhibitor, improves IL-2 production by CD4+ T cells in SLE. This study demonstrates that CD38 affects calcium homeostasis in CD4+ T cells by controlling cell membrane lipid composition that results in suppressed IL-2 production. CD38 inhibition with biologics or small drugs should be expected to benefit patients with SLE.

Polymorphisms of CD247 gene is associated with dilated cardiomyopathy in Chinese Han population

BACKGROUND

Dilated cardiomyopathy (DCM) is a major cause of heart failure and heart transplantation. Recently, some studies have reported that the autoimmune response in myocardial cells might be related to the pathogenesis of DCM. The CD247 gene has been previously found to be involved in autoimmune disease. Therefore, our study aimed to clarify the hypothesis that there is a certain linkage between polymorphisms of the CD247 gene and the triggering of DCM risk.

METHODS

In the present study, two single nucleotide polymorphisms (SNPs) of the CD247 gene, rs12141731 and rs858543, were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 355 DCM patients and 404 age- and sex-matched controls.

RESULTS

Pearson's chi-squared test for the CD247 gene revealed that SNP rs858543 (p = 0.001, OR = 0.72, 95% CI = (0.588-0.882), but not SNP rs12141731, was associated with DCM in the Chinese Han population. Haplotype analysis revealed that the CC haplotype was associated with increased DCM susceptibility, while CT was a protective haplotype. Cox multivariate survival analysis indicated that the rs858543 TT genotype (HR: 0.608, 95% CI = 0.402-0.921, p = 0.019) was an independent multivariate predictor for longer overall survival in DCM patients. CD247 mRNA expression levels were significantly decreased in DCM patients (p = 0.02).

CONCLUSIONS

Our study suggested that a polymorphism in the CD247 gene may be a risk factor for DCM in the Chinese Han population.

TRIAL REGISTRATION

ChiCTR2000029701.

Animal models of studying the pathogenesis of multi-organ tissue damage in lupus

Moderate-to-severe systemic lupus erythematosus (SLE) is characterized by extensive autoantibody deposition and persistent autoinflammation. As the existing animal models are limited in accurately reproducing the pathological characteristics of human SLE, we introduced a novel animal model simulating multi-organ autoinflammation through intra-organ injections. The model closely mimicked key features of SLE, including IgG deposition, inflammation, and tissue damage. The model could be used to assess the roles of IgG, immune cells, cytokines, and Fc gamma receptor (FcγR) in the pathogenesis of autoinflammation. The results obtained from this model could be confirmed by lupus MRL/lpr mice. The review suggested that the diagnostic criteria should be reconsidered to incorporate IgG deposition in tissues and highlighted the limitations of current T-cell and B-cell-focused treatments. To summarize, the IgG deposition model can be used to investigate the pathogenesis and treatment of multi-organ tissue damage associated with SLE.

Relevance of acquired T cell molecular defects in the immunopathogenesis of SLE

Systemic lupus erythematosus (SLE) and other autoimmune diseases are thought to develop in genetically predisposed individuals when triggered by environmental factors. This paradigm does not fully explain disease development, as it fails to consider the delay between birth and disease expression. In this review, we discuss observations described in T cells from patients with SLE that are not related to hereditary factors and have therefore been considered secondary to the disease process itself. Here, we contextualize some of those observations and argue that they may represent a pathogenic layer between genetic factors and disease development. Acquired changes in T cell phenotype and function in the setting of SLE may affect the immune system, creating a predisposition towards a more inflammatory and pathogenic system that amplifies autoimmunity and facilitates disease development.

Functional consequence of Iron dyshomeostasis and ferroptosis in systemic lupus erythematosus and lupus nephritis

Systemic lupus erythematosus (SLE) and its renal manifestation Lupus nephritis (LN) are characterized by a dysregulated immune system, autoantibodies, and injury to the renal parenchyma. Iron accumulation and ferroptosis in the immune effectors and renal tubules are recently identified pathological features in SLE and LN. Ferroptosis is an iron dependent non-apoptotic form of regulated cell death and ferroptosis inhibitors have improved disease outcomes in murine models of SLE, identifying it as a novel druggable target. In this review, we discuss novel mechanisms by which iron accumulation and ferroptosis perpetuate immune cell mediated pathology in SLE/LN. We highlight intra-renal dysregulation of iron metabolism and ferroptosis as an underlying pathogenic mechanism of renal tubular injury. The basic concepts of iron biology and ferroptosis are also discussed to expose the links between iron, cell metabolism and ferroptosis, that identify intracellular pro-ferroptotic enzymes and their protein conjugates as potential targets to improve SLE/LN outcomes.

CaMK4 controls follicular helper T cell expansion and function during normal and autoimmune T-dependent B cell responses

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by dysregulated B cell compartment responsible for the production of autoantibodies. Here, we show that T cell-specific expression of calcium/calmodulin-dependent protein kinase IV (CaMK4) leads to T follicular helper (Tfh) cells expansion in models of T-dependent immunization and autoimmunity. Mechanistically, CaMK4 controls the Tfh-specific transcription factor B cell lymphoma 6 (Bcl6) at the transcriptional level through the cAMP responsive element modulator α (CREMα). In the absence of CaMK4 in T cells, germinal center formation and humoral immunity is impaired in immunized mice, resulting in reduced anti-dsDNA titres, as well as IgG and complement kidney deposition in the lupus-prone B6.lpr mouse. In human Tfh cells, CaMK4 inhibition reduced BCL6 expression and IL-21 secretion ex vivo, resulting in impaired plasmablast formation and IgG production. In patients with SLE, CAMK4 mRNA levels in Tfh cells correlated with those of BCL6. In conclusion, we identify CaMK4/CREMα as a driver of T cell-dependent B cell dysregulation in autoimmunity.

Recent advances in the involvement of epigenetics in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a typical systemic autoimmune disease that manifests as skin rash, arthritis, lymphadenopathy, and multiple organ lesions. Epigenetics, including DNA methylation, histone modification, and non-coding RNA regulation, mainly affect the function and characteristics of cells through the regulation of gene transcription or translation. Increasing evidence indicates that there are a variety of complex epigenetic effects in patients with SLE, which interfere with the differentiation and function of T, and B lymphocytes, monocytes, and neutrophils, and enhance the expression of SLE-associated pathogenic genes. This paper summarizes our currently knowledge regarding pathogenesis of SLE, and introduces current advances in the epigenetic regulation of SLE from three aspects: immune function, inflammatory response, and lupus complications. We propose that epigenetic changes could be used as potential biomarkers and therapeutic targets of SLE.

Peripheral T cell activation, not thymic selection, expands the T follicular helper repertoire in a lupus-prone murine model

Many autoimmune diseases are characterized by the activation of autoreactive T cells. The T cell repertoire is established in the thymus; it remains uncertain whether the presence of disease-associated autoreactive T cells reflects abnormal T cell selection in the thymus or aberrant T cell activation in the periphery. Here, we describe T cell selection, activation, and T cell repertoire diversity in female mice deficient for B lymphocyte-induced maturation protein (BLIMP)-1 in dendritic cells (DCs) (Prdm1 CKO). These mice exhibit a lupus-like phenotype with an expanded population of T follicular helper (Tfh) cells having a more diverse T cell receptor (TCR) repertoire than wild-type mice and, in turn, develop a lupus-like pathology. To understand the origin of the aberrant Tfh population, we analyzed the TCR repertoire of thymocytes and naive CD4 T cells from Prdm1 CKO mice. We show that early development and selection of T cells in the thymus are not affected. Importantly, however, we observed increased TCR signal strength and increased proliferation of naive T cells cultured in vitro with antigen and BLIMP1-deficient DCs compared to control DCs. Moreover, there was increased diversity in the TCR repertoire in naive CD4+ T cells stimulated in vitro with BLIMP1-deficient DCs. Collectively, our data indicate that lowering the threshold for peripheral T cell activation without altering thymic selection and naive T cell TCR repertoire leads to an expanded repertoire of antigen-activated T cells and impairs peripheral T cell tolerance.

Defective LAT signalosome pathology in mice mimics human IgG4-related disease at single-cell level

Mice with a loss-of-function mutation in the LAT adaptor (LatY136F) develop an autoimmune and type 2 inflammatory disorder called defective LAT signalosome pathology (DLSP). We analyzed via single-cell omics the trajectory leading to LatY136F DLSP and the underlying CD4+ T cell diversification. T follicular helper cells, CD4+ cytotoxic T cells, activated B cells, and plasma cells were found in LatY136F spleen and lung. Such cell constellation entailed all the cell types causative of human IgG4-related disease (IgG4-RD), an autoimmune and inflammatory condition with LatY136F DLSP-like histopathological manifestations. Most previously described T cell-mediated autoimmune manifestations require persistent TCR input. In contrast, following their first engagement by self-antigens, the autoreactive TCR expressed by LatY136F CD4+ T cells hand over their central role in T cell activation to CD28 costimulatory molecules. As a result, all subsequent LatY136F DLSP manifestations, including the production of autoantibodies, solely rely on CD28 engagement. Our findings elucidate the etiology of the LatY136F DLSP and qualify it as a model of IgG4-RD.

Germline immunomodulatory expression quantitative trait loci (ieQTLs) associated with immune-related toxicity from checkpoint inhibition

BACKGROUND

Immune checkpoint inhibition (ICI) has improved clinical outcomes for metastatic melanoma patients; however, 65-80% of patients treated with ICI experience immune-related adverse events (irAEs). Given the plausible link of irAEs with underlying host immunity, we explored whether germline genetic variants controlling the expression of 42 immunomodulatory genes were associated with the risk of irAEs in melanoma patients treated with the single-agent anti-CTLA-4 antibody ipilimumab (IPI).

METHODS

We identified 42 immunomodulatory expression quantitative trait loci (ieQTLs) most significantly associated with the expression of 382 immune-related genes. These germline variants were genotyped in IPI-treated melanoma patients, collected as part of a multi-institutional collaboration. We tested the association of ieQTLs with irAEs in a discovery cohort of 95 patients, followed by validation in an additional 97 patients.

RESULTS

We found that the alternate allele of rs7036417, a variant linked to increased expression of SYK, was strongly associated with an increased risk of grade 3-4 toxicity [odds ratio (OR) = 7.46; 95% confidence interval (CI) = 2.65-21.03; p = 1.43E-04]. This variant was not associated with response (OR = 0.90; 95% CI = 0.37-2.21; p = 0.82).

CONCLUSION

We report that rs7036417 is associated with increased risk of severe irAEs, independent of IPI efficacy. SYK plays an important role in B-cell/T-cell expansion, and increased pSYK has been reported in patients with autoimmune disease. The association between rs7036417 and IPI irAEs in our data suggests a role of SYK overexpression in irAE development. These findings support the hypothesis that inherited variation in immune-related pathways modulates ICI toxicity and suggests SYK as a possible future target for therapies to reduce irAEs.

Endosome Traffic Modulates Pro-Inflammatory Signal Transduction in CD4+ T Cells-Implications for the Pathogenesis of Systemic Lupus Erythematosus

Endocytic recycling regulates the cell surface receptor composition of the plasma membrane. The surface expression levels of the T cell receptor (TCR), in concert with signal transducing co-receptors, regulate T cell responses, such as proliferation, differentiation, and cytokine production. Altered TCR expression contributes to pro-inflammatory skewing, which is a hallmark of autoimmune diseases, such as systemic lupus erythematosus (SLE), defined by a reduced function of regulatory T cells (Tregs) and the expansion of CD4⁺ helper T (Th) cells. The ensuing secretion of inflammatory cytokines, such as interferon-γ and interleukin (IL)-4, IL-17, IL-21, and IL-23, trigger autoantibody production and tissue infiltration by cells of the adaptive and innate immune system that induce organ damage. Endocytic recycling influences immunological synapse formation by CD4⁺ T lymphocytes, signal transduction from crosslinked surface receptors through recruitment of adaptor molecules, intracellular traffic of organelles, and the generation of metabolites to support growth, cytokine production, and epigenetic control of DNA replication and gene expression in the cell nucleus. This review will delineate checkpoints of endosome traffic that can be targeted for therapeutic interventions in autoimmune and other disease conditions.

Dysregulation and chronicity of pathogenic T cell responses in the pre-diseased stage of lupus

In the normal immune system, T cell activation is tightly regulated and controlled at several levels to ensure that activation occurs in the right context to prevent the development of pathologic conditions such as autoimmunity or other harmful immune responses. CD4+FoxP3+ regulatory T cells (Treg) are crucial for the regulation of T cell responses in the peripheral lymphatic organs and thus for the prevention and control of autoimmunity. In systemic lupus erythematosus (SLE), a prototypic systemic autoimmune disease with complex etiology, a disbalance between Treg and pathogenic effector/memory CD4+ T cells develops during disease progression indicating that gradual loss of control over T cell activation is an important event in the immune pathogenesis. This progressive failure to adequately regulate the activation of autoreactive T cells facilitates chronic activation and effector/memory differentiation of pathogenic T cells, which are considered to contribute significantly to the induction and perpetuation of autoimmune processes and tissue inflammation in SLE. However, in particular in humans, little is known about the factors which drive the escape from immune regulation and the chronicity of pathogenic T cell responses in an early stage of autoimmune disease when clinical symptoms are still unapparent. Here we briefly summarize important findings and discuss current views and models on the mechanisms related to the dysregulation of T cell responses which promotes chronicity and pathogenic memory differentiation with a focus on the early stage of disease in lupus-prone individuals.

cis interaction of CD153 with TCR/CD3 is crucial for the pathogenic activation of senescence-associated T cells

With age, senescence-associated (SA) CD4⁺ T cells that are refractory to T cell receptor (TCR) stimulation are increased along with spontaneous germinal center (Spt-GC) development prone to autoantibody production. We demonstrate that CD153 and its receptor CD30 are expressed in SA-T and Spt-GC B cells, respectively, and deficiency of either CD153 or CD30 results in the compromised increase of both cell types. CD153 engagement on SA-T cells upon TCR stimulation causes association of CD153 with the TCR/CD3 complex and restores TCR signaling, whereas CD30 engagement on GC B cells induces their expansion. Administration of an anti-CD153 antibody blocking the interaction with CD30 suppresses the increase in both SA-T and Spt-GC B cells with age and ameliorates lupus in lupus-prone mice. These results suggest that the molecular interaction of CD153 and CD30 plays a central role in the reciprocal activation of SA-T and Spt-GC B cells, leading to immunosenescent phenotypes and autoimmunity.

Abnormalities of T cells in systemic lupus erythematosus: new insights in pathogenesis and therapeutic strategies

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by loss of immune tolerance and sustained production of autoantibodies. Multiple and profound T cell abnormalities in SLE are intertwined with disease expression. Both numerical and functional disturbances have been reported in main CD4⁺ T helper cell subsets including Th1, Th2, Th17, regulatory, and follicular helper cells. SLE CD4⁺ T cells are known to provide help to B cells, produce excessive IL-17 but insufficient IL-2, and infiltrate tissues. In the absence of sufficient amounts of IL-2, regulatory T cells, do not function properly to constrain inflammation. A complicated series of early signaling defects and aberrant activation of kinases and phosphatases result in complex cell phenotypes by altering the metabolic profile and the epigenetic landscape. All main metabolic pathways including glycolysis, glutaminolysis and oxidative phosphorylation are altered in T cells from lupus prone mice and patients with SLE. SLE CD8⁺ cytotoxic T cells display reduced cytolytic activity which accounts for higher rates of infection and the sustenance of autoimmunity. Further, CD8⁺ T cells in the context of rheumatic diseases lose the expression of CD8, acquire IL-17⁺CD4^-CD8^- double negative T (DNT) cell phenotype and infiltrate tissues. Herein we present an update on these T cell abnormalities along with underlying mechanisms and discuss how these advances can be exploited therapeutically. Novel strategies to correct these aberrations in T cells show promise for SLE treatment.

Regulating the discriminatory response to antigen by T-cell receptor

The cell-mediated immune response constitutes a robust host defense mechanism to eliminate pathogens and oncogenic cells. T cells play a central role in such a defense mechanism and creating memories to prevent any potential infection. T cell recognizes foreign antigen by its surface receptors when presented through antigen-presenting cells (APCs) and calibrates its cellular response by a network of intracellular signaling events. Activation of T-cell receptor (TCR) leads to changes in gene expression and metabolic networks regulating cell development, proliferation, and migration. TCR does not possess any catalytic activity, and the signaling initiates with the colocalization of several enzymes and scaffold proteins. Deregulation of T cell signaling is often linked to autoimmune disorders like severe combined immunodeficiency (SCID), rheumatoid arthritis, and multiple sclerosis. The TCR remarkably distinguishes the minor difference between self and non-self antigen through a kinetic proofreading mechanism. The output of TCR signaling is determined by the half-life of the receptor antigen complex and the time taken to recruit and activate the downstream enzymes. A longer half-life of a non-self antigen receptor complex could initiate downstream signaling by activating associated enzymes. Whereas, the short-lived, self-peptide receptor complex disassembles before the downstream enzymes are activated. Activation of TCR rewires the cellular metabolic response to aerobic glycolysis from oxidative phosphorylation. How does the early event in the TCR signaling cross-talk with the cellular metabolism is an open question. In this review, we have discussed the recent developments in understanding the regulation of TCR signaling, and then we reviewed the emerging role of metabolism in regulating T cell function.

T Cells, Interleukin-2 and Systemic Lupus Erythematosus—From Pathophysiology to Therapy

The phenotypic and functional complexities of T cells engender complicated and often confusing concepts as to how T cells ignite, accelerate and brake the inflammatory processes involved in systemic lupus erythematosus (SLE), let alone the plasticity of T cells that takes place under different immunological contexts. Nevertheless, being one of the prime survival factors of T cells, interleukin (IL)-2 plays a potentially critical role in many immunological scenarios during the pathophysiological process of SLE. Here, the pathophysiology of lupus T cells and current, as well as ongoing, therapeutic approaches of SLE that involve low-dose IL-2 administration will be highlighted. The mechanisms of IL-2 deficiency in SLE pathophysiology, the effects of low-dose IL-2 on T cells and restoration of lupus manifestations in murine SLE models, as well as the efficacy and safety of clinical trials that evaluated low-dose IL-2-containing regimens in patients with SLE will be discussed.

Analysis of Sepsis Markers and Pathogenesis Based on Gene Differential Expression and Protein Interaction Network

Objective

The purpose of the present study is to screen the hub genes associated with sepsis, comprehensively understand the occurrence and progress mechanism of sepsis, and provide new targets for clinical diagnosis and treatment of sepsis.

Methods

The microarray data of GSE9692 and GSE95233 were downloaded from the Gene Expression Omnibus (GEO) database. The dataset GSE9692 contained 29 children with sepsis and 16 healthy children, while the dataset GSE95233 included 102 septic subjects and 22 healthy volunteers. Differentially expressed genes (DEGs) were screened by GEO2R online analysis. The DAVID database was applied to conduct functional enrichment analysis of the DEGs. The STRING database was adopted to acquire protein-protein interaction (PPI) networks.

Results

We identified 286 DEGs (217 upregulated DEGs and 69 downregulated DEGs) in the dataset GSE9692 and 357 DEGs (236 upregulated DEGs and 121 downregulated DEGs) in the dataset GSE95233. After the intersection of DEGs of the two datasets, a total of 98 co-DEGs were obtained. DEGs associated with sepsis were involved in inflammatory responses such as T cell activation, leukocyte cell-cell adhesion, leukocyte-mediated immunity, cytokine production, immune effector process, lymphocyte-mediated immunity, defense response to fungus, and lymphocyte-mediated immunity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis suggested that sepsis was connected to bacterial and viral infections. Through PPI network analysis, we screened the most important hub genes, including ITK, CD247, MMP9, CD3D, MMP8, KLRK1, and GZMK.

Conclusions

In conclusion, the present study revealed an unbalanced immune response at the transcriptome level of sepsis and identified genes for potential biomarkers of sepsis, such as ITK, CD247, MMP9, CD3D, MMP8, KLRK1, and GZMK.

Dysregulated protein kinase/phosphatase networks in SLE T cells

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease associated with multiple phenotypic and functional aberrations in T lymphocytes. Among these, altered expression and/or activity of several protein kinases and phosphatases has been consistently documented in T cells obtained from patients with SLE. In this review, we describe and contextualize some of the kinase and phosphatase defects reported in T cells from patients with SLE, highlighting their relevance and possible consequences. Additionally, we discuss the origin of the defects and its significance for disease development and expression.

Alternative Splicing: A New Cause and Potential Therapeutic Target in Autoimmune Disease

Alternative splicing (AS) is a complex coordinated transcriptional regulatory mechanism. It affects nearly 95% of all protein-coding genes and occurs in nearly all human organs. Aberrant alternative splicing can lead to various neurological diseases and cancers and is responsible for aging, infection, inflammation, immune and metabolic disorders, and so on. Though aberrant alternative splicing events and their regulatory mechanisms are widely recognized, the association between autoimmune disease and alternative splicing has not been extensively examined. Autoimmune diseases are characterized by the loss of tolerance of the immune system towards self-antigens and organ-specific or systemic inflammation and subsequent tissue damage. In the present review, we summarized the most recent reports on splicing events that occur in the immunopathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and attempted to clarify the role that splicing events play in regulating autoimmune disease progression. We also identified the changes that occur in splicing factor expression. The foregoing information might improve our understanding of autoimmune diseases and help develop new diagnostic and therapeutic tools for them.

Post-translational modifications in T cells in systemic erythematosus lupus

Systemic erythematosus lupus (SLE) is a classic autoimmune disease characterized by multiple autoantibodies and immune-mediated tissue damage. The aetiology of this disease is still unclear. A new drug, belimumab, which acts against the B-lymphocyte stimulator (BLyS), can effectively improve the condition of SLE patients, but it cannot resolve all SLE symptoms. The discovery of novel, precise therapeutic targets is urgently needed. It is well known that abnormal T-cell function is one of the most crucial factors contributing to the pathogenesis of SLE. Protein post-translational modifications (PTMs), including phosphorylation, glycosylation, acetylation, methylation, ubiquitination and SUMOylation have been emphasized for their roles in activating protein activity, maintaining structural stability, regulating protein-protein interactions and mediating signalling pathways, in addition to other biological functions. Summarizing the latest data in this area, this review focuses on the potential roles of diverse PTMs in regulating T-cell function and signalling pathways in SLE pathogenesis, with the goal of identifying new targets for SLE therapy.

Therapeutic perspectives on the metabolism of lymphocytes in patients with rheumatoid arthritis and systemic lupus erythematosus

INTRODUCTION

The activation of autoreactive T- and B-cells and production of autoantibodies by B cells are involved in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Recently, the concept of 'immunometabolism' has attracted significant attention. Immune cells produce large amounts of energy in the form of ATP and biosynthesize biological components such as nucleic acids and lipids via metabolic reprogramming to activate, differentiate, and exert their functions.

AREAS COVERED

While the mechanisms underlying the metabolism of CD4⁺ T cells in SLE have been extensively studied, the metabolic changes underlying B cell activation, differentiation, and function remain unclear. Drugs targeting mTOR and AMPK, such as sirolimus, rapamycin, and metformin, have shown some efficacy and tolerability in clinical trials on patients with SLE, but have not led to breakthroughs. In this review, we summarize the current knowledge on the immunometabolic mechanisms involved in SLE and RA and discuss the potential novel therapeutic drugs.

EXPERT OPINION

The intensity of activation of different immune cells and their metabolic kinetics vary in different autoimmune diseases; thus, understanding the disease- and cell-specific metabolic mechanisms may help in the development of clinically effective immunometabolism-targeting drugs.

Intestinal Dysbiosis and Tryptophan Metabolism in Autoimmunity

The development of autoimmunity involves complex interactions between genetics and environmental triggers. The gut microbiota is an important environmental constituent that can heavily influence both local and systemic immune reactivity through distinct mechanisms. It is therefore a relevant environmental trigger or amplifier to consider in autoimmunity. This review will examine recent evidence for an association between intestinal dysbiosis and autoimmune diseases, and the mechanisms by which the gut microbiota may contribute to autoimmune activation. We will specifically focus on recent studies connecting tryptophan metabolism to autoimmune disease pathogenesis and discuss evidence for a microbial origin. This will be discussed in the context of our current understanding of how tryptophan metabolites regulate immune responses, and how it may, or may not, be applicable to autoimmunity.

Emerging targets for the treatment of lupus erythematosus: There is no royal road to treating lupus

Systemic lupus erythematosus (SLE) is a highly heterogeneous autoimmune disease that preferentially affects women of child-bearing age. Most current treatments for SLE with the exception of belimumab are not target-specific. Nontargeted therapy such as corticosteroids, cyclophosphamide, and other immunosuppressive drugs results in unwanted adverse effects. Although progress in treatment, including supportive therapy, has dramatically improved the prognosis of patients with SLE, better treatment drugs and protocols with fewer adverse effects and higher efficacy for the most severe form of SLE are needed. Advancements in genomics, immunology, and pathophysiology in the field of systemic autoimmunity have provided physicians with increasing knowledge, but the most appropriate treatment for each patient with SLE remains to be established. Therefore, the search for novel treatment targets in patients with SLE is ongoing. This review focuses on recent findings in the genetics of lupus and the abnormalities in cellular interactions, cytokine profiles, and intracellular signaling in patients with SLE. Novel molecular targets for lupus, mostly introduced through clinical trials, are then discussed based on these findings.

CD28 null CD4 T-cell expansions in autoimmune disease suggest a link with cytomegalovirus infection

Immunosenescence is thought to contribute to the increase of autoimmune diseases in older people. Immunosenescence is often associated with the presence of an expanded population of CD4 T cells lacking expression of CD28 (CD28 ^null). These highly cytotoxic CD4 T cells were isolated from disease-affected tissues in patients with rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, or other chronic inflammatory diseases and their numbers appeared to be linked to disease severity. However, we recently demonstrated that the common herpes virus, cytomegalovirus (CMV), not ageing, is the major driver of this subset of cytotoxic T cells. In this review, we discuss how CMV might potentiate and exacerbate autoimmune disease through the expansion of CD28 ^null CD4 T cells.

TARGETING TARGETED TREATMENT FOR IMMUNE AND NON-IMMUNE KIDNEY DISEASES

We have found that calcium calmodulin kinase IV is increased in T cells, podocytes, and mesangial cells from patients with systemic lupus erythematosus, as well as in lupus-prone mice, podocytes of patients with focal segmental glomerulosclerosis, and in mice injected with doxorubicin. We showed that this accounts for aberrant T cell function and glomerular damage. Using nanoparticles (nlg) loaded with a small drug inhibitor of calcium calmodulin kinase IV and tagged with antibodies directed to CD4 we have been able to show inhibition of autoimmunity and lupus nephritis. Also, using nlg tagged with antibodies to nephrin, we showed suppression of nephritis in lupus-prone mice and of glomerular damage in mice exposed to doxorubicin. We propose the development of approaches to deliver drugs to cells in a targeted and precise manner.

Signaling lymphocyte activation molecule family in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by a breakdown in immune tolerance leading to the development of auto-reactive lymphocytes and autoantibodies. Recent findings have provided new insight on the role of the signaling lymphocytic activation molecule family (SLAMF) receptors, a group of nine co-regulatory molecules involved in the activation of hematopoietic cells, and their downstream protein SLAM-associated protein (SAP), into the pathogenesis of SLE. This review summarizes the current knowledge on SLAMF in human SLE immunopathogenesis, and the importance of SLAMF molecules as new therapeutic targets.

Decreased Expression of Serine/Arginine-Rich Splicing Factor 1 in T Cells From Patients With Active Systemic Lupus Erythematosus Accounts for Reduced Expression of RasGRP1 and DNA Methyltransferase 1

OBJECTIVE

T cells from systemic lupus erythematosus (SLE) patients have reduced protein levels of RasGRP1, a guanine nucleotide exchange factor for Ras, and increased transcript of alternatively spliced (AS) forms lacking exon 11. Serine/arginine-rich splicing factor 1 (SRSF1) binds pre-messenger RNA (pre-mRNA) to regulate AS forms of several genes, including CD3ζ in SLE T cells. This study was undertaken to assess whether SRSF1 controls the expression of RasGRP1 in T cells from patients with SLE.

METHODS

We studied T cells from 45 SLE patients and 18 healthy subjects. Expression levels of SRSF1, wild-type (WT) RasGRP1, and DNA methyltransferase 1 (DNMT1) were assessed by quantitative polymerase chain reaction. Direct binding of SRSF1 to exon 11 of RasGRP1 mRNA was evaluated with an oligonucleotide-protein pulldown assay. Healthy T cells and SLE T cells were treated with SRSF1-specific small interfering RNA or SRSF1 expression vector, respectively, and then evaluated for mRNA/protein expression.

RESULTS

SRSF1 expression levels were significantly lower in T cells from SLE patients compared to those from healthy subjects, and correlated inversely with disease activity and positively with levels of RasGRP1-WT and DNMT1. SRSF1 bound directly to exon 11 of RasGRP1 mRNA. Silencing of SRSF1 in human T cells led to increased ratios of RasGRP1-AS to RasGRP1-WT and decreased levels of RasGRP1 protein, whereas overexpression of SRSF1 in SLE T cells caused recovery of RasGRP1, which in turn induced DNMT1/interleukin-2 expression.

CONCLUSION

SRSF1 controls the alternative splicing of RasGRP1 and subsequent protein expression. Our findings extend evidence that alternative splicing plays a central role in the aberrant T cell function in patients with SLE by controlling the expression of multiple genes.

Precision DNA demethylation ameliorates disease in lupus-prone mice

Defective DNA methylation in T cells leads to a series of T cell abnormalities in lupus; however, the full effect of T cell lineage-specific DNA methylation on disease expression has not been explored. Here, we show that 5-azacytidine, a DNA methyltransferase inhibitor, targeted to either CD4 or CD8 T cells in mice with established disease using a nanolipogel delivery system dramatically ameliorates lupus-related pathology through distinct mechanisms. In vivo targeted delivery of 5-azacytidine into CD4 T cells favors the expansion and function of Foxp3+ Tregs, whereas targeted delivery to CD8 T cells enhances the cytotoxicity and restrains the expansion of pathogenic TCR-αβ+CD4-CD8- double-negative T cells. Our results signify the importance of cell-specific inhibition of DNA methylation in the treatment of established lupus.

Aberrant T Cell Signaling and Subsets in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic multi-organ debilitating autoimmune disease, which mainly afflicts women in the reproductive years. A complex interaction of genetics, environmental factors and hormones result in the breakdown of immune tolerance to "self" leading to damage and destruction of multiple organs, such as the skin, joints, kidneys, heart and brain. Both innate and adaptive immune systems are critically involved in the misguided immune response against self-antigens. Dendritic cells, neutrophils, and innate lymphoid cells are important in initiating antigen presentation and propagating inflammation at lymphoid and peripheral tissue sites. Autoantibodies produced by B lymphocytes and immune complex deposition in vital organs contribute to tissue damage. T lymphocytes are increasingly being recognized as key contributors to disease pathogenesis. CD4 T follicular helper cells enable autoantibody production, inflammatory Th17 subsets promote inflammation, while defects in regulatory T cells lead to unchecked immune responses. A better understanding of the molecular defects including signaling events and gene regulation underlying the dysfunctional T cells in SLE is necessary to pave the path for better management, therapy, and perhaps prevention of this complex disease. In this review, we focus on the aberrations in T cell signaling in SLE and highlight therapeutic advances in this field.

Juvenile-onset systemic lupus erythematosus (jSLE) - Pathophysiological concepts and treatment options

The systemic autoimmune/inflammatory condition systemic lupus erythematosus (SLE) manifests before the age of 16 years in 10-20% of all cases. Clinical courses are more severe, and organ complications are more common in patients with juvenile SLE. Varying gender distribution in different age groups and increasing severity with younger age and the presence of monogenic disease in early childhood indicate distinct differences in the pathophysiology of juvenile versus adult-onset SLE. Regardless of these differences, classification criteria and treatment options are identical. In this article, we discuss age-specific pathomechanisms of juvenile-onset SLE, which are currently available and as future treatment options, and propose reclassification of different forms of SLE along the inflammatory spectrum from autoinflammation to autoimmunity.

CD3Z hypermethylation is associated with severe clinical manifestations in systemic lupus erythematosus and reduces CD3ζ-chain expression in T cells

Objective

The importance of hypomethylation in SLE is well recognized; however, the significance of hypermethylation has not been well characterized. We screened hypermethylated marks in SLE and investigated their possible implications.

Methods

DNA methylation marks were screened in SLE whole-blood DNA by microarray, and two marks ( CD3Z and VHL hypermethylations) were confirmed by a methylation single-base extension method in two independent ethnic cohorts consisting of 207 SLE patients and 151 controls. The correlation with clinical manifestations and the genetic influence on those epigenetic marks were analysed.

Results

Two epigenetic marks, CD3Z and VHL hypermethylation, were significantly correlated with SLE: CD3Z hypermethylation (odds ratio = 7.76; P = 1.71 × 10 -13 ) and VHL hypermethylation (odds ratio = 3.77; P = 3.20 × 10 -8 ), and the increased CD3Z methylation was correlated with downregulation of the CD3ζ-chain in SLE T cells. In addition, less genetic influence on CD3Z methylation relative to VHL methylation was found in analyses of longitudinal and twin samples. Furthermore, a higher CD3Z methylation level was significantly correlated with a higher SLE disease activity index and more severe clinical manifestations, such as proteinuria, haemolytic anaemia and thrombocytopenia, whereas VHL hypermethylation was not.

Conclusion

CD3Z hypermethylation is an SLE risk factor that can be modified by environmental factors and is associated with more severe SLE clinical manifestations, which are related to deranged T cell function by downregulating the CD3ζ-chain.

New insights into the immunopathogenesis of systemic lupus erythematosus

The aetiology of systemic lupus erythematosus (SLE) is multifactorial, and includes contributions from the environment, stochastic factors, and genetic susceptibility. Great gains have been made in understanding SLE through the use of genetic variant identification, mouse models, gene expression studies, and epigenetic analyses. Collectively, these studies support the concept that defective clearance of immune complexes and biological waste (such as apoptotic cells), neutrophil extracellular traps, nucleic acid sensing, lymphocyte signalling, and interferon production pathways are all central to loss of tolerance and tissue damage. Increased understanding of the pathogenesis of SLE is driving a renewed interest in targeted therapy, and researchers are now on the verge of developing targeted immunotherapy directed at treating either specific organ system involvement or specific subsets of patients with SLE. Accordingly, this Review places these insights within the context of our current understanding of the pathogenesis of SLE and highlights pathways that are ripe for therapeutic targeting.

Differential Expression of O-Glycans in CD4(+) T Lymphocytes from Patients with Systemic Lupus Erythematosus

T cells from patients with systemic lupus erythematosus (SLE) show a decreased activation threshold and increased apoptosis. These processes seem to be regulated by glycosylated molecules on the T cell surface. Here, we determined through flow cytometry the expression of mucin-type O-glycans on T helper cells in peripheral blood mononuclear cells (PBMC) from 23 SLE patients and its relation with disease activity. We used lectins specific for the disaccharide Gal-GalNAc, such as Amaranthus leucocarpus lectin (ALL), Artocarpus integrifolia lectin (jacalin) and Arachis hypogaea lectin (peanut agglutinin, PNA), as well as lectins for sialic acid such as Sambucus nigra agglutinin (SNA) and Maakia amurensis agglutinin (MAA). The results showed that ALL, but not jacalin or PNA, identified significant differences in O-glycan expression on T helper cells from active SLE patients (n = 10). Moreover, an inverse correlation was found between the frequency of T helper cells recognized by ALL and SLE Disease Activity Index (SLEDAI) score in SLE patients. In contrast, SNA and MAA lectins did not identify any differences between CD4(+) T cells from SLE patients. There was no difference in the recognition by ALL on activated T helper cells and T regulatory (Treg) cells. Our findings point out that activation of SLE disease diminishes the expression of O-glycans in T helper cells; ALL could be considered as a marker to determine activity of the disease.

Immunopathogenesis of systemic lupus erythematosus and rheumatoid arthritis: the role of aberrant expression of non-coding RNAs in T cells

Non-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), are RNA molecules that do not translate into protein. Both miRNAs and lncRNAs are known to regulate gene expression and to play an essential role in T cell differentiation and function. Both systemic lupus erythematosus (SLE), a prototypic systemic autoimmune disease, and rheumatoid arthritis (RA), a representative disease of inflammatory arthritis, are characterized by a complex dysfunction in the innate and adaptive immunity. T cells play a central role in cell-mediated immune response and multiple defects in T cells from patients with SLE and RA have been observed. Abnormality in T cell signalling, cytokine and chemokine production, T cell activation and apoptosis, T cell differentiation and DNA methylation that are associated closely with the aberrant expression of a number of miRNAs and lncRNAs have been implicated in the immunopathogenesis of SLE and RA. This review aims to provide an overview of the current state of research on the abnormal expression of miRNAs and lncRNAs in T cells and their roles in the immunopathogenesis of SLE and RA. In addition, by comparing the differences in aberrant expression of miRNAs and lncRNAs in T cells between patients with SLE and RA, controversial areas are highlighted that warrant further investigation.

CREM Alpha Enhances IL-21 Production in T Cells In Vivo and In Vitro

The cAMP-responsive element modulator alpha (CREMα) plays a role in autoimmunity and, in particular, in systemic lupus erythematosus. CREMα negatively regulates IL-2 transcription and activates IL-17 expression by direct transcriptional mechanisms. To understand the role of CREM in autoimmunity, we recently generated a mouse with a transgenic overexpression of CREMα selectively in T cells. This mouse is characterized by enhanced IL-17 and IL-21 expression. We, herein, dissect the transcriptional mechanisms of enhanced IL-21 transcription in these mice. T cells of CREMα transgenic mice display an enhanced binding of CREMα to the CD3ζ chain promoter resulting in decreased CD3ζ chain expression. This is accompanied by a decreased excitation threshold and enhanced Ca²⁺ influx, which is known to induce IL-21 expression via NFATc2 activation. However, CREMα directly binds to cAMP-response element (CRE) half-site within the Il-21 promoter, which results in enhanced promoter activity shown by promoter reporter assays. CREMα-induced IL-21 transcription is not abrogated in the presence of cyclosporine A but depends on an intact CRE site within the IL-21 promoter, which suggests that CREM largely enhances IL-21 expression by direct transcriptional regulation. IL-21 transcription is critical for IL-17 generation in these mice, since IL-21 receptor blockade downregulates IL-17 transcription to wild-type levels. Finally, this is of functional relevance since CREMα transgenic mice display enhanced disease activity in dextran sodium sulfate-induced colitis accompanied by higher local IL-21 expression. Thus, we describe two novel mechanisms of CREMα-dependent IL-21 transcription. Since T cells of systemic lupus erythematosus patients are characterized by enhanced IL-21 transcription, this might also be of functional relevance in humans.

Estrogen receptor alpha promotes lupus in (NZB×NZW)F1 mice in a B cell intrinsic manner

Lupus is a systemic autoimmune disease characterized by the production of autoreactive antibodies against nuclear antigens. Women are disproportionately affected by lupus, and this sex bias is thought to be due, in large part, to the ability of estrogens to promote lupus pathogenesis. Previously, we have shown that global deletion of estrogen receptor alpha (ERα) significantly attenuated loss of tolerance, immune cell activation, autoantibody production, and the development of lupus nephritis. Here we show that targeted deletion of ERα specifically in B cells retards production of pathogenic autoantibodies and the development of nephritis in lupus-prone (NZB×NZW)F1 mice. Furthermore, we observed that ERα deletion in B cells was associated with decreased B cell activation in young, pre-autoimmune (NZB×NZW)F1 females. Altogether, these data suggest that ERα acts in a B cell-intrinsic manner to control B cell activation, autoantibody production, and lupus nephritis.

Decreased SAP Expression in T Cells from Patients with Systemic Lupus Erythematosus Contributes to Early Signaling Abnormalities and Reduced IL-2 Production

T cells from patients with systemic lupus erythematosus (SLE) display a number of abnormalities, including increased early signaling events following engagement of the TCR. Signaling lymphocytic activation molecule family cell surface receptors and the X-chromosome-defined signaling lymphocytic activation molecule-associated protein (SAP) adaptor are important in the development of several immunocyte lineages and modulating the immune response. We present evidence that SAP protein levels are decreased in T cells and in their main subsets isolated from 32 women and three men with SLE, independent of disease activity. In SLE T cells, SAP protein is also subject to increased degradation by caspase-3. Forced expression of SAP in SLE T cells normalized IL-2 production, calcium (Ca(2+)) responses, and tyrosine phosphorylation of a number of proteins. Exposure of normal T cells to SLE serum IgG, known to contain anti-CD3/TCR Abs, resulted in SAP downregulation. We conclude that SLE T cells display reduced levels of the adaptor protein SAP, probably as a result of continuous T cell activation and degradation by caspase-3. Restoration of SAP levels in SLE T cells corrects the overexcitable lupus T cell phenotype.

T cells as a therapeutic target in SLE

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease characterized by a loss of tolerance to multiple endogenous antigens. SLE etiology remains largely unknown, despite recent insight into the immunopathogenesis of the disease. T cells are important in the development of the disease by amplifying the immune response and contributing to organ damage. Aberrant signaling, cytokine secretion, and tissue homing displayed by SLE T cells have been extensively studied and the underlying pathogenic molecular mechanisms are starting to be elucidated. T-cell-targeted treatments are being explored in SLE patients. This review is an update on the T-cell abnormalities and related therapeutic options in SLE.

In HIV-positive patients, myeloid-derived suppressor cells induce T-cell anergy by suppressing CD3ζ expression through ELF-1 inhibition

OBJECTIVE

During HIV infection, a down-modulation of CD3ζ was found on T cells, contributing to T-cell anergy. In this work, we studied the correlation between myeloid-derived suppressor cells (MDSC) frequency and T-cell CD3ζ expression. Moreover, we investigated the mechanisms of CD3ζ decrease exploited by MDSC.

DESIGN AND METHOD

CD3ζ expression and MDSC frequency were evaluated by flow cytometry on peripheral blood mononuclear cells from 105 HIV-positive (HIV+) patients. The role of MDSC in the modulation of the HIV-specific T-cell response was evaluated. The level of CD3ζ mRNA and ELF-1 protein were analysed by real-time-PCR and western blot, respectively.

RESULTS

We found that granulocytic-MDSC (Gr-MDSC) were expanded in HIV+ patients compared with healthy donors; in particular, in cART-treated individuals a higher Gr-MDSC frequency was observed in patients with a CD4 T-cell count below 400 cells/μl. We found an inverse correlation between the percentage of Gr-MDSC and CD3ζ level. Moreover, in-vitro MDSC depletion induced the up-regulation of CD3ζ in T cells, restoring the functionality of αβ, but not γδ T cells. The in-vitro effect of isolated MDSC on CD3ζ expression was found cell contact-dependent, and was not mediated by previously described molecules. CD3ζ down-modulation corresponds to the decrease of its mRNA induced by silencing the transcription factor ELF-1.

CONCLUSION

Our data provide new knowledge on mechanisms used by Gr-MDSC in immune-modulation and on their role in the immune reconstitution during antiviral treatments.

The Emerging and Diverse Roles of Src-Like Adaptor Proteins in Health and Disease

Although Src-like adaptor proteins (SLAP-1 and SLAP-2) were mainly studied in lymphocytes, where they act as negative regulators and provide fine control of receptor signaling, recently, several other functions of these proteins were discovered. In addition to the well-characterized immunoregulatory functions, SLAP proteins appear to have an essential role in the pathogenesis of type I hypersensitivity, osteoporosis, and numerous malignant diseases. Both adaptor proteins are expressed in a wide variety of tissues, where they have mostly inhibitory effects on multiple intracellular signaling pathways. In this review, we summarize the diverse effects of SLAP proteins.

Serine Arginine-Rich Splicing Factor 1 (SRSF1) Contributes to the Transcriptional Activation of CD3ζ in Human T Cells

T lymphocytes from many patients with systemic lupus erythematosus (SLE) express decreased levels of the T cell receptor (TCR)-associated CD3 zeta (ζ) signaling chain, a feature directly linked to their abnormal phenotype and function. Reduced mRNA expression partly due to defective alternative splicing, contributes to the reduced expression of CD3ζ chain. We previously identified by oligonucleotide pulldown and mass spectrometry approaches, the serine arginine-rich splicing factor 1 (SRSF1) binding to the 3’ untranslated region (UTR) of CD3ζ mRNA. We showed that SRSF1 regulates alternative splicing of the 3’UTR of CD3ζ to promote expression of the normal full length 3`UTR over an unstable splice variant in human T cells. In this study we show that SRSF1 regulates transcriptional activation of CD3ζ. Specifically, overexpression and silencing of SRSF1 respectively increases and decreases CD3ζ total mRNA and protein expression in Jurkat and primary T cells. Using promoter-luciferase assays, we show that SRSF1 enhances transcriptional activity of the CD3ζ promoter in a dose dependent manner. Chromatin immunoprecipitation assays show that SRSF1 is recruited to the CD3ζ promoter. These results indicate that SRSF1 contributes to transcriptional activation of CD3ζ. Thus our study identifies a novel mechanism whereby SRSF1 regulates CD3ζ expression in human T cells and may contribute to the T cell defect in SLE.

Genetic association of CD247 (CD3ζ) with SLE in a large-scale multiethnic study

A classic T-cell phenotype in systemic lupus erythematosus (SLE) is the downregulation and replacement of the CD3ζ chain that alters T-cell receptor signaling. However, genetic associations with SLE in the human CD247 locus that encodes CD3ζ are not well established and require replication in independent cohorts. Our aim was therefore to examine, localize and validate CD247-SLE association in a large multiethnic population. We typed 44 contiguous CD247 single-nucleotide polymorphisms (SNPs) in 8922 SLE patients and 8077 controls from four ethnically distinct populations. The strongest associations were found in the Asian population (11 SNPs in intron 1, 4.99 × 10(-4) < P < 4.15 × 10(-2)), where we further identified a five-marker haplotype (rs12141731-rs2949655-rs16859085-rs12144621-rs858554; G-G-A-G-A; P(hap) = 2.12 × 10(-5)) that exceeded the most associated single SNP rs858554 (minor allele frequency in controls = 13%; P = 4.99 × 10(-4), odds ratio = 1.32) in significance. Imputation and subsequent association analysis showed evidence of association (P < 0.05) at 27 additional SNPs within intron 1. Cross-ethnic meta-analysis, assuming an additive genetic model adjusted for population proportions, showed five SNPs with significant P-values (1.40 × 10(-3) < P< 3.97 × 10(-2)), with one (rs704848) remaining significant after Bonferroni correction (P(meta) = 2.66 × 10(-2)). Our study independently confirms and extends the association of SLE with CD247, which is shared by various autoimmune disorders and supports a common T-cell-mediated mechanism.