Abnormalities of T cell signaling in systemic lupus erythematosus

Autoimmune rheumatic disease IgG has differential effects upon neutrophil integrin activation that is modulated by the endothelium

The importance of neutrophils in the pathogenesis of autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), is increasingly recognised. Generation of reactive oxygen species (ROS) and release of neutrophil extracellular traps (NETs) by activated neutrophils are both thought to contribute to pathology; although the underlying mechanisms, particularly the effects of IgG autoantibodies upon neutrophil function, are not fully understood. Therefore, we determined whether purified IgG from patients with SLE or RA have differential effects upon neutrophil activation and function. We found that SLE- and RA-IgG both bound human neutrophils but differentially regulated neutrophil function. RA- and SLE-IgG both increased PMA-induced β₁ integrin-mediated adhesion to fibronectin, whilst only SLE-IgG enhanced α_Mβ₂ integrin-mediated adhesion to fibrinogen. Interestingly, only SLE-IgG modulated neutrophil adhesion to endothelial cells. Both SLE- and RA-IgG increased ROS generation and DNA externalisation by unstimulated neutrophils. Only SLE-IgG however, drove DNA externalisation following neutrophil activation. Co-culture of neutrophils with resting endothelium prevented IgG-mediated increase of extracellular DNA, but this inhibition was overcome for SLE-IgG when the endothelium was stimulated with TNF-α. This differential pattern of neutrophil activation has implications for understanding SLE and RA pathogenesis and may highlight avenues for development of novel therapeutic strategies.

A rare regulatory variant in the MEF2D gene affects gene regulation and splicing and is associated with a SLE sub-phenotype in Swedish cohorts

Systemic lupus erythematosus (SLE) is an autoimmune disorder with heterogeneous clinical presentation and complex etiology involving the interplay between genetic, epigenetic, environmental and hormonal factors. Many common SNPs identified by genome wide-association studies (GWAS) explain only a small part of the disease heritability suggesting the contribution from rare genetic variants, undetectable in GWAS, and complex epistatic interactions. Using targeted re-sequencing of coding and conserved regulatory regions within and around 215 candidate genes selected on the basis of their known role in autoimmunity and genes associated with canine immune-mediated diseases, we identified a rare regulatory variant rs200395694:G > T located in intron 4 of the MEF2D gene encoding the myocyte-specific enhancer factor 2D transcription factor and associated with SLE in Swedish cohorts (504 SLE patients and 839 healthy controls, p = 0.014, CI = 1.1–10). Fisher’s exact test revealed an association between the genetic variant and a triad of disease manifestations including Raynaud, anti-U1-ribonucleoprotein (anti-RNP), and anti-Smith (anti-Sm) antibodies (p = 0.00037) among the patients. The DNA-binding activity of the allele was further studied by EMSA, reporter assays, and minigenes. The region has properties of an active cell-specific enhancer, differentially affected by the alleles of rs200395694:G > T. In addition, the risk allele exerts an inhibitory effect on the splicing of the alternative tissue-specific isoform, and thus may modify the target gene set regulated by this isoform. These findings emphasize the potential of dissecting traits of complex diseases and correlating them with rare risk alleles with strong biological effects.

Oxidative Modifications in Tissue Pathology and Autoimmune Disease

SIGNIFICANCE

Various autoimmune syndromes are characterized by abnormalities found at the level of tissues and cells, as well as by microenvironmental influences, such as reactive oxygen species (ROS), that alter intracellular metabolism and protein expression. Moreover, the convergence of genetic, epigenetic, and even environmental influences can result in B and T lymphocyte autoimmunity and tissue pathology. Recent Advances: This review describes how oxidative stress to cells and tissues may alter post-translational protein modifications, both directly and indirectly, as well as potentially lead to aberrant gene expression. For example, it has been clearly observed in many systems how oxidative stress directly amplifies carbonyl protein modifications. However, ROS also lead to a number of nonenzymatic spontaneous modifications including deamidation and isoaspartate modification as well as to enzyme-mediated citrullination of self-proteins. ROS have direct effects on DNA methylation, leading to influences in gene expression, chromosome inactivation, and the silencing of genetic elements. Finally, ROS can alter many other cellular pathways, including the initiation of apoptosis and NETosis, triggering the release of modified intracellular autoantigens.

CRITICAL ISSUES

This review will detail specific post-translational protein modifications, the pathways that control autoimmunity to modified self-proteins, and how products of ROS may be important biomarkers of tissue pathogenesis.

FUTURE DIRECTIONS

A clear understanding of the many pathways affected by ROS will lead to potential therapeutic manipulations to alter the onset and/or progression of autoimmune disease.

Kidney-infiltrating T cells in murine lupus nephritis are metabolically and functionally exhausted

While T cells are important for the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis, little is known about how T cells function after infiltrating the kidney. The current paradigm suggests that kidney-infiltrating T cells (KITs) are activated effector cells contributing to tissue damage and ultimately organ failure. Herein, we demonstrate that the majority of CD4+ and CD8+ KITs in 3 murine lupus models are not effector cells, as hypothesized, but rather express multiple inhibitory receptors and are highly dysfunctional, with reduced cytokine production and proliferative capacity. In other systems, this hypofunctional profile is linked directly to metabolic and specifically mitochondrial dysfunction, which we also observed in KITs. The T cell phenotype was driven by the expression of an "exhausted" transcriptional signature. Our data thus reveal that the tissue parenchyma has the capability of suppressing T cell responses and limiting damage to self. These findings suggest avenues for the treatment of autoimmunity based on selectively exploiting the exhausted phenotype of tissue-infiltrating T cells.

Emerging areas for therapeutic discovery in SLE

Recent advances in the field of autoimmunity have identified numerous dysfunctional pathways in Systemic Lupus Erythematosus (SLE), including aberrant clearance of nucleic-acid-containing debris and immune complexes, excessive innate immune activation leading to overactive type I IFN signalling, and abnormal B and T cell activation. On the background of genetic polymorphisms that reset thresholds for immune responses, multiple immune cells contribute to inflammatory amplification circuits. Neutrophils activated by immune complexes are a rich source of immunogenic nucleic acids. Identification of new B subsets suggests several mechanisms for induction of autoantibody producing effector cells. Disordered T cell regulation involves both CD4 and CD8 cells. An imbalance in immunometabolism in immune cells amplifies autoimmunity and inflammation. These new advances in understanding of disease pathogenesis provide fertile ground for therapeutic development.

Long-term effects of tacrolimus for maintenance therapy of lupus nephritis: a 5-year retrospective study at a single center

Previously, we reported the short-term effects of tacrolimus in treating lupus nephritis (LN); however, long-term data are lacking. We conducted a retrospective study of 26 adult patients with LN. Tacrolimus was initiated at a dose of 3 mg/day after induction therapy. We retrospectively collected data on renal response; modified lupus nephritis disease activity index (m-LNDAI), including hematuria, proteinuria, complement 3, anti-double-stranded DNA antibody, and estimated glomerular filtration rate (eGFR); and prednisolone (PSL) dose. Three patients discontinued tacrolimus treatment because of related complications, including acute myeloblastic leukemia, tremor, or a general personal choice or a desire to become pregnant. We analyzed data from 23 patients who were treated with tacrolimus over a 5-year period. The mean urinary protein/creatinine ratio decreased from a baseline of 0.24 (min 0.00-max 4.20) to 0.00 (0.00-7.05) at 5 years (p = 0.0134), while eGFR levels remained unchanged throughout the 5 years. The mean m-LNDAI decreased from a baseline of 3.00 (0.00-12.0) to 2.00 (0.00-4.00) at 5 years (p = 0.0074). The mean PSL dose decreased from a baseline of 0.33 (0.00-0.75) mg/kg/day to 0.15 (0.15-0.33) at 5 years (p = 0.001). Our results suggest that tacrolimus is potentially effective for treating LN and that the current dosage was generally well tolerated for long-term maintenance treatment in our patients with LN.

Effect of a Combination of Prednisone or Mycophenolate Mofetil and Mesenchymal Stem Cells on Lupus Symptoms in MRL.Faslpr Mice

The combination of immunosuppressants and mesenchymal stem cells (MSCs) is a promising therapeutic strategy for systemic lupus erythematosus, since this approach reduces doses of immunosuppressants while maintaining the same therapeutic outcome. However, it is unavoidable for MSCs to be exposed to immunosuppressants. Here, we examined the combination effect of prednisone (PD) or mycophenolate mofetil (MMF) and MSCs. We showed that PD or MMF in combination with MSCs showed better therapeutic effect than single therapy in lupus-prone MRL.Fas^lpr mice, as assessed by using the following readouts: prolongation of survival, decrease in anti-dsDNA and total IgG levels in serum, decrease in cytokine gene expression in spleen cells, and decrease in inflammatory cell infiltration into the kidney. In vitro, immunosuppressants and MSCs inhibited T cell proliferation in a synergistic manner. However, immunosuppressants did not affect MSC viability and functions such as TGF-β1 and PGE₂ production, migration, and immunosuppressive capacity. In summary, our study demonstrates that a combination of immunosuppressants and MSCs is a good strategy to reduce the side effects of PD and MMF without the loss of therapeutic outcome.

Decreased T cell expression of H/ACA box small nucleolar RNA 12 promotes lupus pathogenesis in patients with systemic lupus erythematosus

Objective To investigate whether the aberrant expression of non-coding RNAs (ncRNAs) in T cells from patients with systemic lupus erythematosus (SLE) could contribute to the pathogenesis of lupus. Methods Expression profiles of RNA transcripts in T cells from three patients with SLE and three controls were analyzed by microarray analysis. Potentially aberrant-expressed ncRNAs were validated using T cell samples from 23 patients with SLE and 17 controls. Transfection studies and microarray analyses were conducted to search for any gene expression that is regulated by specific ncRNAs. Results Initial analysis revealed differential expression of 18 ncRNAs in SLE T cells. After validation, decreased expression of H/ACA box small nucleolar RNA 12 (SNORA12) was confirmed in SLE T cells (0.69-fold, P = 0.007) compared with normal T cells, and its expression level was inversely associated with higher SLE disease activity scores. Jurkat cells transfected with a plasmid encoding SNORA12 showed increased expression of two genes and decreased expression of 15 genes in Jurkat cells. These changes of gene expression were significantly associated with the SLE pathway in the Kyoto Encyclopedia of Genes and Genomes map using microarray analysis. Overexpression of SNORA12 altered the expression of CD69, decreased the expression of histone cluster 1 H4 family member k (HIST1H4K), inhibited the secretion of interferon gamma and the expression of HIST1H4K was increased in SLE T cells. Conclusion Among the ncRNAs, we found that the expression level of SNORA12, which belongs to the family of small nucleolar RNAs, was lower in SLE T cells and affected T cell function. This novel finding suggests that aberrant-expressed snoRNAs lead to dysfunction of T cells and may be involved in the immunopathogenesis of SLE.

Mesenchymal stem cells and T cells in the formation of Tertiary Lymphoid Structures in Lupus Nephritis

Tertiary lymphoid structures (TLS) develop in the kidneys of lupus-prone mice and systemic lupus erythematosus (SLE) patients with lupus nephritis (LN). Here we investigated the presence of mesenchymal stem cells (MSCs) in the development of TLS in murine LN, as well as the role of human MSCs as lymphoid tissue organizer (LTo) cells on the activation of CD4+ T cells from three groups of donors including Healthy, SLE and LN patients. Mesenchymal stem like cells were detected within the pelvic wall and TLS in kidneys of lupus-prone mice. An increase in LTβ, CXCL13, CCL19, VCAM1 and ICAM1 gene expressions were detected during the development of murine LN. Human MSCs stimulated with the pro-inflammatory cytokines TNF-α and IL-1β significantly increased the expression of CCL19, VCAM1, ICAM1, TNF-α, and IL-1β. Stimulated MSCs induced proliferation of CD4⁺ T cells, but an inhibitory effect was observed when in co-culture with non-stimulated MSCs. A contact dependent increase in Th2 and Th17 subsets were observed for T cells from the Healthy group after co-culture with stimulated MSCs. Our data suggest that tissue-specific or/and migratory MSCs could have pivotal roles as LTo cells in accelerating early inflammatory processes and initiating the formation of kidney specific TLS in chronic inflammatory conditions.

The Involvement of MicroRNAs in Modulation of Innate and Adaptive Immunity in Systemic Lupus Erythematosus and Lupus Nephritis

Noncoding RNAs (ncRNAs), including microRNAs (miRNAs), represent a family of RNA molecules that do not translate into protein. Nevertheless, they have the ability to regulate gene expression and play an essential role in immune cell differentiation and function. MicroRNAs were found to be differentially expressed in various tissues, and changes in their expression have been associated with several pathological processes. Yet, their roles in systemic lupus erythematosus (SLE) and lupus nephritis (LN) remain to be elucidated. Both SLE and LN are characterized by a complex dysfunction of the innate and adaptive immunity. Recently, significant findings have been made in understanding SLE through the use of genetic variant identification and expression pattern analysis and mouse models, as well as epigenetic analyses. Abnormalities in immune cell responses, cytokine and chemokine production, cell activation, and apoptosis have been linked to a unique expression pattern of a number of miRNAs that have been implicated in the immune pathogenesis of this autoimmune disease. The recent evidence that significantly increased the understanding of the pathogenesis of SLE drives a renewed interest in efficient therapy targets. This review aims at providing an overview of the current state of research on the expression and role of miRNAs in the immune pathogenesis of SLE and LN.

Ozanimod (RPC1063), a selective S1PR1 and S1PR5 modulator, reduces chronic inflammation and alleviates kidney pathology in murine systemic lupus erythematosus

Ozanimod (RPC1063) is a specific and potent small molecule modulator of the sphingosine 1-phosphate receptor 1 (S1P_R1) and receptor 5 (S1P_R5), which has shown therapeutic benefit in clinical trials of relapsing multiple sclerosis and ulcerative colitis. Ozanimod and its active metabolite, RP-101075, exhibit a similar specificity profile at the S1P receptor family in vitro and pharmacodynamic profile in vivo. The NZBWF1 mouse model was used in therapeutic dosing mode to assess the potential benefit of ozanimod and RP-101075 in an established animal model of systemic lupus erythematosus. Compared with vehicle-treated animals, ozanimod and RP-101075 reduced proteinuria over the duration of the study and serum blood urea nitrogen at termination. Additionally, ozanimod and RP-101075 reduced kidney disease in a dose-dependent manner, as measured by histological assessment of mesangial expansion, endo- and exo-capillary proliferation, interstitial infiltrates and fibrosis, glomerular deposits, and tubular atrophy. Further exploration into gene expression changes in the kidney demonstrate that RP-101075 also significantly reduced expression of fibrotic and immune-related genes in the kidneys. Of note, RP-101075 lowered the number of plasmacytoid dendritic cells, a major source of interferon alpha in lupus patients, and reduced all B and T cell subsets in the spleen. Given the efficacy demonstrated by ozanimod and its metabolite RP-101075 in the NZBWF1 preclinical animal model, ozanimod may warrant clinical evaluation as a potential treatment for systemic lupus erythematosus.

Establishment of the Reference Intervals of Lymphocyte Function in Healthy Adults Based on IFN-γ Secretion Assay upon Phorbol-12-Myristate-13-Acetate/Ionomycin Stimulation

The function of lymphocytes is the key to reflect the immune status of hosts. Evaluation of lymphocyte function is a useful tool to monitor the effect of immunosuppressive treatment and predict the prognosis of immune-mediated diseases (e.g., cancer, autoimmune diseases, and infectious diseases). As the lymphocytes have various activities, such as activation, cytotoxicity, and cytokine secretion, it is a challenge to evaluate the function of lymphocytes in clinical practice and the reference intervals (RIs) of lymphocyte function are rarely reported. The present study showed that the secretion of IFN-γ was well correlated with the activation, chemotaxis, and cytotoxicity of CD4⁺, CD8⁺ T cells, and NK cells, which suggests that IFN-γ production can be used as a symbol of lymphocyte function. We therefore created a simple method to detect the function of CD4⁺, CD8⁺ T cells, and NK cells simultaneously according to IFN-γ secretion by using whole blood instead of peripheral blood mononuclear cells. We further established the RIs of lymphocyte function (CD4⁺ T cells: 15.31-34.98%; CD8⁺ T cells: 26.11-66.59%; NK cells: 39.43-70.79%) in healthy adults. This method showed good reproducibility for the evaluation of lymphocyte function. The established RIs were suitable for use in other centers based on the validation data. We also validated the RIs in individuals with different immune status, and the results showed that kidney transplant recipients and infants (0-1 year) had a decreased lymphocyte function, whereas T cells in systemic lupus erythematosus patients exhibited an opposite trend. Overall, we have successfully established the RIs of lymphocyte function in healthy adults in a simple way, which might be of important clinical value in the diagnosis, monitoring, and prognosis of immune-related diseases.

Insulin-like growth factor-1 (IGF1) in systemic lupus erythematosus: relation to disease activity, organ damage and immunological findings

Background Insulin growth factor-1 (IGF1) activates cell proliferation pathways and inhibits apoptosis. IGF1 is involved in tumour growth and required for T-cell independent activation of B cells. Activated B cells and autoantibody production are a hallmark of systemic lupus erythematosus (SLE). To investigate the possible role of IGF1 in SLE, we studied IGF1 across clinical characteristics, immunological biomarkers, disease activity and organ damage in SLE patients. Method In a cross-sectional study, we collected clinical characteristics, medication, disease activity (SLEDAI-2K) and organ damage (SDI) for 94 SLE patients. Autoantibodies and cytokines were measured by ELISA, and levels of IGF1 and IGF binding protein 3 (IGFBP3) by chemiluminescence. Free IGF1 was estimated by the IGF1:IGFBP3 ratio. Healthy controls served as a comparator group. Results There was a significant age-related decline in IGF1, IGFBP3 and free IGF1 (IGF1:IGFBP3 ratio) that was similar in SLE patients and controls with very few outliers. Free IGF1 was inversely related to blood pressure (Rs -0.327, p < 0.01) and HbA1c (Rs -0.31, p < 0.01). Free IGF1 was higher in disease-modifying antirheumatic drug-treated patients ( p < 0.01), but there was no significant association between the IGF1 axis and autoantibody profiles, cytokine levels or SLEDAI-2K or SDI categories. IGF1 correlated inversely with BAFF level and B, natural killer and CD8 + cell counts. Conclusion Free IGF1 levels in SLE patients declined appropriately with age. IGF1 levels were not associated with disease activity, severity or autoantibody levels in SLE. Free IGF1 had positive metabolic effects in SLE and may play an indirect role in dampening the cellular immune response by downregulating B- and T-cell activity.

Two separate effects contribute to regulatory T cell defect in systemic lupus erythematosus patients and their unaffected relatives

Forkhead box P3 (FoxP3)⁺ regulatory T cells (T_regs) are functionally deficient in systemic lupus erythematosus (SLE), characterized by reduced surface CD25 [the interleukin (IL)‐2 receptor alpha chain]. Low‐dose IL‐2 therapy is a promising current approach to correct this defect. To elucidate the origins of the SLE T_reg phenotype, we studied its role through developmentally defined regulatory T cell (T_reg) subsets in 45 SLE patients, 103 SLE‐unaffected first‐degree relatives and 61 unrelated healthy control subjects, and genetic association with the CD25‐encoding IL2RA locus. We identified two separate, uncorrelated effects contributing to T_reg CD25. (1) SLE patients and unaffected relatives remarkably shared CD25 reduction versus controls, particularly in the developmentally earliest CD4⁺FoxP3⁺CD45RO^–CD31⁺ recent thymic emigrant T_regs. This first component effect influenced the proportions of circulating CD4⁺FoxP3^highCD45RO⁺ activated T_regs. (2) In contrast, patients and unaffected relatives differed sharply in their activated T_reg CD25 state: while relatives as control subjects up‐regulated CD25 strongly in these cells during differentiation from naive T_regs, SLE patients specifically failed to do so. This CD25 up‐regulation depended upon IL2RA genetic variation and was related functionally to the proliferation of activated T_regs, but not to their circulating numbers. Both effects were found related to T cell IL‐2 production. Our results point to (1) a heritable, intrathymic mechanism responsible for reduced CD25 on early T_regs and decreased activation capacity in an extended risk population, which can be compensated by (2) functionally independent CD25 up‐regulation upon peripheral T_reg activation that is selectively deficient in patients. We expect that T_reg‐directed therapies can be monitored more effectively when taking this distinction into account.

Dysregulated CD46 shedding interferes with Th1-contraction in systemic lupus erythematosus

IFN‐γ‐producing T helper 1 (Th1) cell responses mediate protection against infections but uncontrolled Th1 activity also contributes to a broad range of autoimmune diseases. Autocrine complement activation has recently emerged as key in the induction and contraction of human Th1 immunity: activation of the complement regulator CD46 and the C3aR expressed by CD4⁺ T cells via autocrine generated ligands C3b and C3a, respectively, are critical to IFN‐γ production. Further, CD46‐mediated signals also induce co‐expression of immunosuppressive IL‐10 in Th1 cells and transition into a (self)‐regulating and contracting phase. In consequence, C3 or CD46‐deficient patients suffer from recurrent infections while dysregulation of CD46 signaling contributes to Th1 hyperactivity in rheumatoid arthritis and multiple sclerosis. Here, we report a defect in CD46‐regulated Th1 contraction in patients with systemic lupus erythematosus (SLE). We observed that MMP‐9‐mediated increased shedding of soluble CD46 by Th1 cells was associated with this defect and that inhibition of MMP‐9 activity normalized release of soluble CD46 and restored Th1 contraction in patients’ T cells. These data may deliver the first mechanistic explanation for the increased serum CD46 levels observed in SLE patients and indicate that targeting CD46‐cleaving proteases could be a novel avenue to modulate Th1 responses.

Association of IL -6 -174 G>C polymorphism with the risk of SLE among south Indians: evidence from case-control study and meta-analysis

Cytokines play a direct role in disease pathogenesis of systemic lupus erythematosus (SLE). Elevated levels of serum IL-6 are well documented with the disease activity and anti-dsDNA antibodies in SLE. The 5' promoter region of the IL-6 gene has been shown to play a significant role in the regulation of gene expression. In view of this, the current study aimed to investigate the possible association of 5' promoter polymorphisms G-597A (rs1800797), G-572C (rs1800796) and G-174C (rs1800795) with the risk of SLE. Analysis of 468 subjects (202 SLE patients and 266 controls) showed a significant association of the -174 G/C variant with the SLE risk in both dominant and recessive model (odds ratio (OR) 3.20, 95% confidence interval (CI) 1.18-8.69, P = 0.020 and OR 2.02, 95% CI 1.35-3.02, P = 0.0005), respectively. The 'G allele of the -174 loci (OR 1.97, 95% CI 1.39-2.78, P = 0.00012) has shown significant distribution between the cases and controls. The haplotype analysis revealed that AGG haplotype carriers are more frequent in cases than controls and found a significant positive association (OR 1.394, 95% CI 1.07-7.12, P = 0.028) with SLE. In addition, we also undertook a meta-analysis on 13 study groups for -174 G/C, comprising a total of 1585 cases and 1690 controls. The pooled OR also suggested a significant association of -174 G/C with SLE (OR 1.36, 95% CI 1.22-1.53, P < 0.05). In conclusion, the presence of the G allele at the IL-6 polymorphic promoter loci -174 is a risk factor and might influence SLE disease and pathogenesis. Meta-analysis has also suggested the overall correlation between -174 G/C polymorphism and SLE risk.

Elevated expression of TIGIT on CD3+CD4+ T cells correlates with disease activity in systemic lupus erythematosus

Objectives

It is well-known that lymphocytes play an important role in systemic lupus erythematosus (SLE). T cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory domains (TIGIT) is one of immunosuppressive costimulatory molecules that mediates an inhibitory effect. However, its roles in SLE are poorly understood. This study was designed to investigate the correlation between the frequencies of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes and SLE.

Methods

Patients with SLE were recruited from the First Affiliated Hospital of Nanchang University. Medical history, clinical manifestations, physical examination and laboratory measurements were recorded. The expression of TIGIT on CD3⁺ T lymphocytes, B lymphocytes, monocytes, neutrophils, CD3⁺CD4⁺ T lymphocytes and CD3⁺CD8⁺ T lymphocytes were determined by flow cytometry. The frequencies of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes in patients with SLE were further analyzed for correlations with markers of autoimmune response, inflammation, urine proteins and disease activity in SLE.

Results

The frequency of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes was significantly elevated in SLE patients compared with healthy controls (P < 0.0001). The frequency of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes in patients with SLE was increased significantly in subjects with high anti-dsDNA titer (P = 0.026), high anti-Sm titer (P = 0.026), and high levels of urine microalbumin (P = 0.046). Furthermore, The frequency of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes was found to be positively correlated with the Disease Activity Index (SLEDAI) score in SLE (r² = 0.082; P = 0.044).

Conclusion

In SLE, the frequency of TIGIT-expressing CD3⁺CD4⁺ T lymphocytes was elevated and associated with the disease activity.

Systemic lupus erythematosus in the light of the regulatory effects of galectin-1 on T-cell function

Galectin-1 is an endogenous immunoregulatory lectin-type protein. Its most important effects are the inhibition of the differentiation and cytokine production of Th1 and Th17 cells, and the induction of apoptosis of activated T-cells. Galectin-1 has been identified as a key molecule in antitumor immune surveillance, and data are accumulating about the pathogenic role of its deficiency, and the beneficial effects of its administration in various autoimmune disease models. Initial animal and human studies strongly suggest deficiencies in both galectin-1 production and responsiveness in systemic lupus erythematosus (SLE) T-cells. Since lupus features widespread abnormalities in T-cell activation, differentiation and viability, in this review the authors wished to highlight potential points in T-cell signalling processes that may be influenced by galectin-1. These points include GM-1 ganglioside-mediated lipid raft aggregation, early activation signalling steps involving p56Lck, the exchange of the CD3 ζ-ZAP-70 to the FcRγ-Syk pathway, defective mitogen-activated protein kinase pathway activation, impaired regulatory T-cell function, the failure to suppress the activity of interleukin 17 (IL-17) producing T-cells, and decreased suppression of the PI3K-mTOR pathway by phosphatase and tensin homolog (PTEN). These findings place galectin-1 into the group of potential pathogenic molecules in SLE.

Cathepsin K Deficiency Ameliorates Systemic Lupus Erythematosus-like Manifestations in Faslpr Mice

Cysteinyl cathepsin K (CatK) is expressed in osteoclasts to mediate bone resorption, but is also inducible under inflammatory conditions. Fas^lpr mice on a C57BL/6 background develop spontaneous systemic lupus erythematosus-like manifestations. Although normal mouse kidneys expressed negligible CatK, those from Fas^lpr mice showed elevated CatK expression in the glomeruli and tubulointerstitial space. Fas^lpr mice also showed elevated serum CatK levels. CatK deficiency in Fas^lpr mice reduced all tested kidney pathologies, including glomerulus and tubulointerstitial scores, glomerulus complement C3 and IgG deposition, chemokine expression and macrophage infiltration, and serum autoantibodies. CatK contributed to Fas^lpr mouse autoimmunity and pathology in part by its activity in TLR-7 proteolytic processing and consequent regulatory T (Treg) cell biology. Elevated TLR7 expression and proteolytic processing in Fas^lpr mouse kidneys and Tregs showed significantly reduced levels in CatK-deficient mice, leading to increased spleen and kidney Treg content. Purified CD4⁺CD25^highFoxp3⁺ Tregs from CatK-deficient mice doubled their immunosuppressive activity against T effector cells, compared with those from CatK-sufficient mice. In Fas^lpr mice, repopulation of purified Tregs from CatK-sufficient mice reduced spleen sizes, autoantibody titers, and glomerulus C3 and IgG deposition, and increased splenic and kidney Treg contents. Tregs from CatK-deficient mice had significantly more potency than CatK-sufficient Tregs in reducing spleen sizes, serum autoantibody titers, and glomerulus C3 deposition, and in increasing splenic and kidney Treg content. This study established a possible role of CatK in TLR7 proteolytic activation, Treg immunosuppressive activity, and lupus autoimmunity and pathology.

Changes in Frequency and Activation Status of Major CD4+ T-Cell Subsets after Initiation of Immunosuppressive Therapy in a Patient with New Diagnosis Childhood-Onset Systemic Lupus Erythematosus

BACKGROUND

Several studies suggest that defects of regulatory T-cells (Tregs) and impaired cellular immunity are secondary to an imbalance between auto-aggressive T-cells and Tregs in lupus patients. Discrepancies in Tregs and effector T-cells (Teff) in active lupus patients are shown to be restored in patients upon receiving immunosuppressive therapy. Therefore, our main aim was to observe frequencies of these CD4⁺ T-cell subsets and Tregs/Teff ratio in a new diagnosis of childhood-onset systemic lupus erythematous (cSLE) before and after initiation of therapy. In addition, we monitored T-cell exhaustion status by examining responses to super-antigen staphylococcal enterotoxin B (SEB) and PD-1 expression in this patient.

METHODS

Phenotyping of CD4⁺ T-cell subsets was carried out under basal conditions and after SEB stimulation using flow cytometry in one inactive (I-cSLE) and one active cSLE (A-cSLE) patient, as well as a healthy control (HC). The A-cSLE patient was a new diagnosis. Variables were measured at three consecutive time points in the active patient, reflecting various stages of disease activity. Activation status of CD4⁺ T-cells in the A-cSLE patient was compared to that of the I-cSLE patient and HC. Disease activity was measured by calculating the systemic lupus erythematous disease activity index.

RESULTS

We found that the A-cSLE patient was not Tregs deficient. The patient had increased frequency of Tregs, and the Tregs/Teff ratio increased when the disease activity became less severe. CD4⁺ T-cells in the I-cSLE patient and in the A-cSLE patient with milder disease activity had heightened responsiveness to SEB, whereas T-cells were relatively hypo-responsive to SEB in the A-cSLE patient when disease activity was higher. The active patient exhibited higher frequencies of PD-1⁺ expressing Tregs, Teff, and Tnaïve/mem cells under basal conditions compared to the HC and I-cSLE patient.

CONCLUSION

In the A-cSLE patient, changes in Tregs/Teff ratio correlated better with clinical improvement compared to Tregs frequencies alone and might reflect the restoration of immune homeostasis with therapy. SEB hypo-responsiveness in the A-cSLE patient when disease activity was higher paralleled with findings of greater frequencies of PD-1⁺ expressing Tregs, Teff, and Tnaïve/mem cells, suggests a possible global exhaustion status of CD4⁺ T-cells in this patient.

The sphingosine-1-phosphate receptor: A novel therapeutic target for multiple sclerosis and other autoimmune diseases

Multiple sclerosis (MS) is a prototype autoimmune disease of the central nervous system (CNS). Currently, there is no drug that provides a cure for MS. To date, all immunotherapeutic drugs target relapsing remitting MS (RR-MS); it remains a daunting medical challenge in MS to develop therapy for secondary progressive MS (SP-MS). Since the approval of the non-selective sphingosine-1-phosphate (S1P) receptor modulator FTY720 (fingolimod [Gilenya®]) for RR-MS in 2010, there have been many emerging studies with various selective S1P receptor modulators in other autoimmune conditions. In this article, we will review how S1P receptor may be a promising therapeutic target for SP-MS and other autoimmune diseases such as psoriasis, polymyositis and lupus.

RNA-seq Analysis Reveals Unique Transcriptome Signatures in Systemic Lupus Erythematosus Patients with Distinct Autoantibody Specificities

Systemic lupus erythematosus (SLE) patients exhibit immense heterogeneity which is challenging from the diagnostic perspective. Emerging high throughput sequencing technologies have been proved to be a useful platform to understand the complex and dynamic disease processes. SLE patients categorised based on autoantibody specificities are reported to have differential immuno-regulatory mechanisms. Therefore, we performed RNA-seq analysis to identify transcriptomics of SLE patients with distinguished autoantibody specificities. The SLE patients were segregated into three subsets based on the type of autoantibodies present in their sera (anti-dsDNA+ group with anti-dsDNA autoantibody alone; anti-ENA+ group having autoantibodies against extractable nuclear antigens (ENA) only, and anti-dsDNA+ENA+ group having autoantibodies to both dsDNA and ENA). Global transcriptome profiling for each SLE patients subsets was performed using Illumina® Hiseq-2000 platform. The biological relevance of dysregulated transcripts in each SLE subsets was assessed by ingenuity pathway analysis (IPA) software. We observed that dysregulation in the transcriptome expression pattern was clearly distinct in each SLE patients subsets. IPA analysis of transcripts uniquely expressed in different SLE groups revealed specific biological pathways to be affected in each SLE subsets. Multiple cytokine signaling pathways were specifically dysregulated in anti-dsDNA+ patients whereas Interferon signaling was predominantly dysregulated in anti-ENA+ patients. In anti-dsDNA+ENA+ patients regulation of actin based motility by Rho pathway was significantly affected. The granulocyte gene signature was a common feature to all SLE subsets; however, anti-dsDNA+ group showed relatively predominant expression of these genes. Dysregulation of Plasma cell related transcripts were higher in anti-dsDNA+ and anti-ENA+ patients as compared to anti-dsDNA+ ENA+. Association of specific canonical pathways with the uniquely expressed transcripts in each SLE subgroup indicates that specific immunological disease mechanisms are operative in distinct SLE patients' subsets. This 'sub-grouping' approach could further be useful for clinical evaluation of SLE patients and devising targeted therapeutics.

Role of galectin-3 in autoimmune and non-autoimmune nephropathies

Galectins are evolutionary conserved β-galactoside binding proteins with a carbohydrate-recognition domain (CRD) of approximately 130 amino acids. In mammals, 15 members of the galectin family have been identified and classified into three subtypes according to CRD organization: prototype, tandem repeat-type and chimera-type galectins. Galectin-3 (gal-3) is the only chimera type galectin in vertebrates containing one CRD linked to an unusual long N-terminal domain which displays non-lectin dependent activities. Although recent studies revealed unique, pleiotropic and context-dependent functions of gal-3 in both extracellular and intracellular space, gal-3 specific pathways and its ligands have not been clearly defined yet. In the kidney gal-3 is involved in later stages of nephrogenesis as well as in renal cell cancer. However, gal-3 has recently been associated with lupus glomerulonephritis, with Familial Mediterranean Fever-induced proteinuria and renal amyloidosis. Gal-3 has been studied in experimental acute kidney damage and in the subsequent regeneration phase as well as in several models of chronic kidney disease, including nephropathies induced by aging, ischemia, hypertension, diabetes, hyperlipidemia, unilateral ureteral obstruction and chronic allograft injury. Because of the pivotal role of gal-3 in the modulation of immune system, wound repair, fibrosis and tumorigenesis, it is not surprising that gal-3 can be an intriguing prognostic biomarker as well as a promising therapeutic target in a great variety of diseases, including chronic kidney disease, chronic heart failure and cardio-renal syndrome. This review summarizes the functions of gal-3 in kidney pathophysiology focusing on the reported role of gal-3 in autoimmune diseases.

Increased risk of systemic lupus erythematosus in pregnancy-induced hypertension: A nationwide population-based retrospective cohort study

Dysregulation of the immune system plays a role in the pathogenesis of both, pregnancy-induced hypertension (PIH) and systemic lupus erythematosus (SLE). It is well known that SLE predisposes to be complicated with PIH. However, few studies have attempted to investigate whether PIH increased subsequent SLE risk.The objectives of this study were to assess the association between PIH and subsequent SLE risk and identify predictive risk factors.Patients with newly diagnosed PIH were selected from the Taiwan National Health Insurance Research Database (NHIRD) and compared with a matched cohort without PIH based on age and the year of delivery. The incidence of new-onset SLE was evaluated in both cohorts. The overall observational period was from January 1, 2000 to December 31, 2013.Among the 23.3 million individuals registered in the NHIRD, 29,091 patients with PIH and 116,364 matched controls were identified. The incidence of SLE was higher among patients with PIH than in the matched controls (incidence rate ratio [IRR] = 4.02, 95% confidence interval [CI] 3.98-4.05, P < 0.0001). The IRR for subsequent SLE development remained significantly higher in all stratifications during the follow-up years. The multivariate Cox regression model was performed and the results showed that PIH may be an independent risk factors for the development of subsequent SLE (hazard ratio [HR] = 2.87, 95% CI 2.07-3.98, P < 0.0001). Moreover, multivariate Cox regression model was used again among the PIH cohort only in order to identify the possible risk factors for subsequent SLE in the population with PIH.Patients with PIH may have higher risk of developing newly diagnosed SLE than those without PIH. In addition, among individuals who have experienced PIH, those younger than 30 years, having experienced preeclampsia/eclampsia, single parity, preterm birth, or chronic kidney disease, may display an increased subsequent risk of SLE.

CD275-Independent IL-17-Producing T Follicular Helper-like Cells in Lymphopenic Autoimmune-Prone Mice

T cells undergo homeostatic expansion and acquire an activated phenotype in lymphopenic microenvironments. Restoration of normal lymphocyte numbers typically re-establishes normal homeostasis, and proinflammatory cytokine production returns to baseline. Mice deficient in guanine nucleotide exchange factor RasGRP1 exhibit dysregulated homeostatic expansion, which manifests as lymphoproliferative disease with autoantibody production. Our previous work revealed that autoreactive B cells lacking RasGRP1 break tolerance early during development, as well as during germinal center responses, suggesting that T cell-independent and T cell-dependent mechanisms are responsible. Examination of whether a particular T cell subset is involved in the breach of B cell tolerance revealed increased Th17 cells in Rasgrp1-deficient mice relative to control mice. Rasgrp1-deficient mice lacking IL-17R had fewer germinal centers, and germinal centers that formed contained fewer autoreactive B cells, suggesting that IL-17 signaling is required for a break in B cell tolerance in germinal centers. Interestingly, a fraction of Th17 cells from Rasgrp1-deficient mice were CXCR5(+) and upregulated levels of CD278 coordinate with their appearance in germinal centers, all attributes of T follicular helper cells (Tfh17). To determine whether CD278-CD275 interactions were required for the development of Tfh17 cells and for autoantibody, Rasgrp1-deficient mice were crossed with CD275-deficient mice. Surprisingly, mice deficient in RasGRP1 and CD275 formed Tfh17 cells and germinal centers and produced similar titers of autoantibodies as mice deficient in only RasGRP1. Therefore, these studies suggest that requirements for Tfh cell development change in lymphopenia-associated autoimmune settings.

Selective Loss of Signaling Lymphocytic Activation Molecule Family Member 4-Positive CD8+ T Cells Contributes to the Decreased Cytotoxic Cell Activity in Systemic Lupus Erythematosus

OBJECTIVE

Engagement of signaling lymphocytic activation molecule family member 4 (SLAMF4; CD244, 2B4) by its ligand SLAMF2 (CD48) modulates the function and expansion of both natural killer cells and a subset of cytotoxic CD8+ T cells. Because the cytotoxicity of CD8+ T lymphocytes isolated from patients with systemic lupus erythematosus (SLE) is known to be impaired, the aim of this study was to assess whether the expression and function of the checkpoint regulator SLAMF4 are altered on CD8+ T cells from patients with SLE.

METHODS

The expression of SLAMF4 by T cells from healthy donors and patients with SLE was determined by quantitative polymerase chain reaction and flow cytometry. T cells were activated with anti-CD3 antibody, and degranulation activity was monitored by the surface expression of lysosome-associated membrane protein 1 (LAMP-1; CD107a). The SLAMF4+ and SLAMF4- CD8+ T cell subpopulations were characterized by LAMP-1, perforin, and granzyme B expression and viral peptide-induced proliferation.

RESULTS

SLAMF4 gene and surface protein expression was down-regulated in CD8+ T cells from SLE patients compared with that in cells obtained from healthy donors. Importantly, SLE patients had significantly fewer SLAMF4+ CD8+ T cells compared with healthy donors. SLAMF4- CD8+ T cells from SLE patients had a decreased cytotoxic capacity and decreased proliferative responses to viral peptides. The loss of memory SLAMF4+ CD8+ T cells in SLE patients was linked to the fact that these cells have an increased propensity to lose CD8 expression and become double-negative T cells.

CONCLUSION

A selective loss of SLAMF4+ CD8+ T cells contributes to the compromised ability of T cells from patients with SLE to fight infection.

Targeted therapeutics in SLE: emerging strategies to modulate the interferon pathway

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by impaired immune tolerance, resulting in the generation of pathogenic autoantibodies and immune complexes. Although autoreactive B lymphocytes have been the first targets for biologic therapies in SLE, the importance of the innate immune system, and in particular, pathways involved in interferon (IFN) signaling, has emerged. There are now data supporting a central role for a plasmacytoid dendritic cell-derived type I IFN pathway in SLE, with a number of biologic therapeutics and small-molecule inhibitors undergoing clinical trials. Monoclonal antibodies targeting IFN-α have completed phase II clinical trials, and an antibody against the type I IFN receptor is entering a phase III trial. However, other IFNs, such as IFN gamma, and the more recently discovered type III IFNs, are also emerging as targets in SLE; and blockade of upstream components of the IFN signaling pathway may enable inhibition of more than one IFN subtype. In this review, we discuss the current understanding of IFNs in SLE, focusing on emerging therapies.

Targeting Syk in Autoimmune Rheumatic Diseases

Spleen tyrosine kinase (Syk) is a member of the Src family of non-receptor tyrosine kinases, which associates directly with surface receptors, including B-cell receptor and Fcγ receptor, and is involved in a variety of signal transduction pathways. Rheumatoid arthritis (RA) and systemic lupus erythematosus are autoimmune diseases in which autoantibodies, immune complexes, and autoreactive T cells account for the expression of tissue inflammation and damage. Syk inhibitors efficiently suppress RA in patients albeit in the expression of unwanted side effects, including gastrointestinal effects, hypertension, and neutropenia. Syk inhibitors also inhibit clinical manifestations in lupus-prone mice. Here, we review the evidence that supports the use of Syk inhibitors to treat rheumatic and other autoimmune diseases.

Activation of mTOR (mechanistic target of rapamycin) in rheumatic diseases

Mechanistic target of rapamycin (mTOR, also known as mammalian target of rapamycin) is a ubiquitous serine/threonine kinase that regulates cell growth, proliferation and survival. These effects are cell-type-specific, and are elicited in response to stimulation by growth factors, hormones and cytokines, as well as to internal and external metabolic cues. Rapamycin was initially developed as an inhibitor of T-cell proliferation and allograft rejection in the organ transplant setting. Subsequently, its molecular target (mTOR) was identified as a component of two interacting complexes, mTORC1 and mTORC2, that regulate T-cell lineage specification and macrophage differentiation. mTORC1 drives the proinflammatory expansion of T helper (TH) type 1, TH17, and CD4(-)CD8(-) (double-negative, DN) T cells. Both mTORC1 and mTORC2 inhibit the development of CD4(+)CD25(+)FoxP3(+) T regulatory (TREG) cells and, indirectly, mTORC2 favours the expansion of T follicular helper (TFH) cells which, similarly to DN T cells, promote B-cell activation and autoantibody production. In contrast to this proinflammatory effect of mTORC2, mTORC1 favours, to some extent, an anti-inflammatory macrophage polarization that is protective against infections and tissue inflammation. Outside the immune system, mTORC1 controls fibroblast proliferation and chondrocyte survival, with implications for tissue fibrosis and osteoarthritis, respectively. Rapamycin (which primarily inhibits mTORC1), ATP-competitive, dual mTORC1/mTORC2 inhibitors and upstream regulators of the mTOR pathway are being developed to treat autoimmune, hyperproliferative and degenerative diseases. In this regard, mTOR blockade promises to increase life expectancy through treatment and prevention of rheumatic diseases.

Association of CTLA4 exon-1 polymorphism with the tumor necrosis factor-α in the risk of systemic lupus erythematosus among South Indians

Cytotoxic T lymphocyte associated-antigen (CTLA4) is a potential negative regulatory molecule of T-cells and associated with several autoimmune diseases. Several reports from different ethnic groups showed that the polymorphisms of the CTLA4 gene have been associated with autoimmune diseases including SLE. Therefore, we aimed to investigate the +49 A/G polymorphism in South Indian SLE patients and its association with disease aetiology and serological markers. A total of 534 samples were genotyped for the +49 A/G polymorphism in exon 1 of the CTLA-4 gene through PCR-RFLP method. We found significant association of genotype and allele frequencies with +49 A/G polymorphism in SLE patients. The frequency of the +49 A/G polymorphism rs231775 'GG' genotype was significantly higher in patients with SLE (12.32%) than those in healthy control subjects (4.6%) (OR: 1.797; 95% CI 1.264-2.554; p=0.001). The frequency of mutant allele 'G' also found to be significantly higher in cases (36.01%) than controls (24.92%) (OR: 1.695, 95% CI: 1.298-2.214, p<0.001). We observed significant increase in serum TNF-α, interferon-α, IL-10 and IL-12 in SLE cases compared to controls. We also found a significant association of serum TNF-α, interferon-α, IL-10 and IL-12 with SLE phenotypes. In addition there was a significant increase in serum TNF-α level in "GG" genotype SLE subjects suggesting that it might play a major role in the advancement of SLE disease.

Up-regulation of Serum MiR-130b-3p Level is Associated with Renal Damage in Early Lupus Nephritis

Systemic lupus erythematosus (SLE) is a common but severe autoimmune systemic inflammatory disease. Lupus nephritis (LN) is a serious complication of SLE,affecting up to 70% of SLE patients. Circulating microRNAs (miRNA) are emerging as biomarkers for pathological conditions and play significant roles in intercellular communication. In present research, serum samples from healthy control, early and late stage LN patients were used to analyze the expression profile of miRNAs by microarray. Subsequent study demonstrated that miR-130b-3p in serum of patients with early stage LN were significantly up-regulated when compared with healthy controls. In addition,we have also observed that the expression of a large amount of circulating microRNAs significantly decreased in patients with late stage LN. The further analysis found that the expression of serum miR-130b-3p was positively correlated with 24-hour proteinuria and renal chronicity index in patients with early stage LN.Transfection of renal tubular cellline(HK-2)with miR-130b-3p mimics can promote epithelial-mesenchymal transition (EMT). The opposite effects were observed when transfected with miR-130b-3p inhibitors. MiR-130b-3p negatively regulated ERBB2IP expression by directly targeting the 3′-UTR of ERBB2IP The circulating miR-130b-3p might serve as a biomarker and play an important role in renal damage in early stage LN patients.

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.

Increased Tim-3 expression on peripheral T lymphocyte subsets and association with higher disease activity in systemic lupus erythematosus

Background

Both the T cell immunoglobulin domain- and mucin domain-containing molecule-3 (Tim-3) and the death receptor Fas contribute to the pathogenesis of various autoimmune diseases, including systemic lupus erythematosus (SLE). The aim of the present study was to determine whether Tim-3 and Fas are co-expressed on certain peripheral T lymphocyte subsets, and whether this expression is associated with greater disease activity in SLE.

Methods

Peripheral blood mononuclear cells were isolated from 46 patients newly diagnosed with SLE and 28 age- and sex-matched healthy controls (HCs). Expression of Tim-3 and Fas on T subsets was analyzed by flow cytometry, while mRNA levels of the Tim-3 ligand galectin-9 and Fas ligand FasL were assayed using real-time RT-PCR.

Results

The proportions of CD3⁺CD4⁺ and CD3⁺CD4^- T cells expressing Tim-3⁺ and Tim⁺Fas⁺ were significantly higher in patients than in HCs (p < 0.05), while the proportions of these subtypes expressing Fas were similar for the two groups. Patients with active SLE, as defined by their score on the SLE Disease Activity Index, had lower proportions of CD3⁺CD4⁺ T cells and higher proportions of CD3⁺CD4⁺Tim-3⁺ and CD3⁺CD4⁺Tim-3⁺Fas⁺ T cells than did patients with stable SLE. Serum levels of complement C3 and C4 proteins, considered as a marker of SLE activity, correlated negatively with proportions of CD3⁺CD4⁺ and CD3⁺CD4^- T cells expressing Tim-3.

Conclusions

Expression of Tim-3 and co-expression of Tim-3 and Fas on certain peripheral T subsets are associated with disease activity in SLE patients. Future research should examine whether the same is true of other T subsets implicated in SLE, and should explore the potential role(s) of Tim-3 in the disease pathway.

Virtual slides

http://www.diagnosticpathology.diagnomx.eu/vs/1855527845145188

Expression and Polymorphisms of Lysosome-Associated Protein Transmembrane 5 (LAPTM5) in Patients with Systemic Lupus Erythematosus in a Chinese Population

Lysosome-associated protein transmembrane 5 (LAPTM5) have been demonstrated a role in the prevention of lymphocyte hyperactivation, and its deficiency is involved in the immunological dysfunction of mouse models. The aim of this study was to detect mRNA expression of LAPTM5 in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE), and to assess association between LAPTM5 single nucleotide polymorphisms (SNPs) (rs10798801, rs4614309, rs1188348, and rs1188349) and SLE in a Chinese population. Real-time transcription-polymerase chain reaction analysis was used to determine expression of LAPTM5 mRNA in PBMCs from 132 patients with SLE and 62 healthy controls. LAPTM5 mRNA expression decreased in SLE patients (n = 71) compared with healthy controls (n = 58) (p = 3.68 × 10(-5)). The expression of LAPTM5 mRNA in SLE patients with lupus nephritis (LN) (n = 35) was lower than in those without LN (n = 36) (p = 0.004). The expression level of LAPTM5 correlated with serum total protein (r(s) = 0.41, p = 0.027) and negatively correlated with 24-h proteinuria (r(s) = -0.45, p = 0.027). LAPTM5 SNPs (rs10798801, rs4614309, rs1188348, and rs1188349) was also analyzed by restriction fragment length polymorphism (RFLP) in 380 SLE patients and 460 healthy controls. No significant difference in the genotype or allele frequencies for LAPTM5 SNPs was detected in 380 SLE patients and 460 healthy controls (p > 0.05). Substantially low frequency of GGAT haplotype was observed in SLE patients (p < 0.001). It is concluded that insufficient expression of LAPTM5 may take part in the pathogenesis of SLE and contribute to the severity of the disease, and none of LAPTM5 polymorphisms contributes significantly to SLE susceptibility in a Chinese population.

The HSP90 Inhibitor Ganetespib Alleviates Disease Progression and Augments Intermittent Cyclophosphamide Therapy in the MRL/lpr Mouse Model of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex, systemic autoimmune disease with a diverse range of immunological and clinical manifestations. The introduction of broad spectrum immunosuppressive therapies and better management of acute disease exacerbations have improved outcomes for lupus patients over recent years. However, these regimens are burdened by substantial toxicities and confer significantly higher risks of infection, thus there remains a significant and unmet medical need for alternative treatment options, particularly those with improved safety profiles. Heat shock protein 90 (HSP90) is a ubiquitously expressed molecular chaperone that acts as an important modulator of multiple innate and adaptive inflammatory processes. Of note, accumulating clinical and experimental evidence has implicated a role for HSP90 in the pathogenesis of SLE. Here we evaluated the potential of HSP90 as a therapeutic target for this disease using the selective small molecule inhibitor ganetespib in the well-characterized MRL/lpr autoimmune mouse model. In both the prophylactic and therapeutic dosing settings, ganetespib treatment promoted dramatic symptomatic improvements in multiple disease parameters, including suppression of autoantibody production and the preservation of renal tissue integrity and function. In addition, ganetespib exerted profound inhibitory effects on disease-related lymphadenopathy and splenomegaly, and reduced pathogenic T and B cell lineage populations in the spleen. Ganetespib monotherapy was found to be equally efficacious and tolerable when compared to an effective weekly dosing regimen of the standard-of-care immunosuppressive agent cyclophosphamide. Importantly, co-treatment of ganetespib with a sub-optimal, intermittent dosing schedule of cyclophosphamide resulted in superior therapeutic indices and maximal disease control. These findings highlight the potential of HSP90 inhibition as an alternative, and potentially complementary, strategy for therapeutic intervention in SLE. Such approaches may have important implications for disease management, particularly for limiting or preventing treatment-related toxicities, a major confounding factor in current SLE therapy.

The paradoxical roles of C1q and C3 in autoimmunity

In this review we will focus on the links between complement and autoimmune diseases and will highlight how animal models have provided insights into the manner by which C1q and C3 act to modulate both adaptive and innate immune responses. In particular we will highlight how C1q may not only act as initiator of the classical complement pathway, but can also mediate multiple immune responses in a complement activation independent manner.

T cell signaling abnormalities contribute to aberrant immune cell function and autoimmunity

Systemic lupus erythematosus (SLE) is a prototype systemic autoimmune disease that results from a break in immune tolerance to self-antigens, leading to multi-organ destruction. Autoantibody deposition and inflammatory cell infiltration in target organs such as kidneys and brain lead to complications of this disease. Dysregulation of cellular and humoral immune response elements, along with organ-defined molecular aberrations, form the basis of SLE pathogenesis. Aberrant T lymphocyte activation due to signaling abnormalities, linked to defective gene transcription and altered cytokine production, are important contributors to SLE pathophysiology. A better understanding of signaling and gene regulation defects in SLE T cells will lead to the identification of specific novel molecular targets and predictive biomarkers for therapy.

mTOR activation is a biomarker and a central pathway to autoimmune disorders, cancer, obesity, and aging

The mechanistic target of rapamycin (mTOR) is a ubiquitous serine/threonine kinase, which plays pivotal roles in integrating growth signals on a cellular level. To support proliferation and survival under stress, two interacting complexes that harbor mTOR, mTORC1 and mTORC2, promote the transcription of genes involved in carbohydrate metabolism and lipogenesis, enhance protein translation, and inhibit autophagy. Although rapamycin was originally developed as an inhibitor of T cell proliferation for preventing organ transplant rejection, its molecular target, mTOR, has been subsequently identified as a central regulator of metabolic cues that drive lineage specification in the immune system. Owing to oxidative stress, the activation of mTORC1 has emerged as a central pathway for the pathogenesis of systemic lupus erythematosus and other autoimmune diseases. Paradoxically, mTORC1 has also been identified as a mediator of the Warburg effect that allows cell survival under hypoxia. Rapamycin and new classes of mTOR inhibitors are being developed to block not only transplant rejection and autoimmunity but also to treat obesity and various forms of cancer. Through preventing these diseases, personalized mTOR blockade holds promise to extend life span.

Autoantibodies specific to D4GDI modulate Rho GTPase mediated cytoskeleton remodeling and induce autophagy in T lymphocytes

T lymphocytes from patients with Systemic Lupus Erythematosus (SLE) display multiple abnormalities, including increased cell activation, abnormal cell death by apoptosis and impairment of autophagy pathway. In the present study we report the presence of specific antibodies to D4GDI, a small GTPase family inhibitor, in a significant percentage (46%) of SLE patient sera. We also found a significant association between the presence of these autoantibodies and hematologic manifestations occurring in these patients. Investigating the possible implication of anti-D4GDI autoantibodies in SLE pathogenesis or progression, we found that these antibodies were capable of binding D4GDI expressed at the lymphocyte surface and triggering a series of subcellular events, including Rho GTPase activation. These antibodies were also able to induce autophagy in T cells from both healthy donors and SLE patients, but only those negative to these antibodies. We can conclude that anti-D4GDI autoantibodies could be capable of triggering important responses in T cells such as cytoskeleton remodeling and autophagy pathway and that, in SLE patients, the chronic exposure to these specific autoantibodies could lead to the selection of autophagy-resistant T cell clones contributing to the pathogenesis of the disease.

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.

CD47-dependent regulation of H₂S biosynthesis and signaling in T cells

Pharmacological concentrations of H2S donors inhibit some T cell functions by inhibiting mitochondrial function, but evidence is also emerging that H2S at physiological concentrations produced via chemical sources and endogenously is a positive physiological mediator of T cell function. Expression of the H2S biosynthetic enzymes cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS) is induced in response to T cell receptor signaling. Inhibiting the induction of these enzymes limits T cell activation and proliferation, which can be overcome by exposure to exogenous H2S at submicromolar concentrations. Exogenous H2S at physiological concentrations increases the ability of T cells to form an immunological synapse by altering cytoskeletal actin dynamics and increasing the reorientation of the microtubule-organizing center. Downstream, H2S enhances T cell receptor-dependent induction of CD69, CD25, and Interleukin-2 (IL-2) gene expression. The T cell stimulatory activity of H2S is enhanced under hypoxic conditions that limit its oxidative metabolism by mitochondrial and nonenzymatic processes. Studies of the receptor CD47 have revealed the first endogenous inhibitory signaling pathway that regulates H2S signaling in T cells. Binding of the secreted protein thrombospondin-1 to CD47 elicits signals that block the stimulatory activity of exogenous H2S on T cell activation and limit the induction of CSE and CBS gene expression. CD47 signaling thereby inhibits T cell receptor-mediated T cell activation.

A pathogenic role for ER stress-induced autophagy and ER chaperone GRP78/BiP in T lymphocyte systemic lupus erythematosus

Abnormal regulation of ER stress and apoptosis has been implicated in autoimmune disorders. Particularly, ER stress-induced autophagy and the role of GRP78, or BiP in T lymphocyte survival and death in SLE are poorly understood. This study investigated the pathogenic roles of ER stress-induced autophagy and GRP78/BiP in apoptosis of T lymphocytes. We compared spontaneous and induced autophagy and apoptosis of T lymphocytes in healthy donors and patients with SLE. The molecular mechanism of altered autophagy and apoptosis was investigated in T lymphocytes transfected with siRNA for beclin 1 and CHOP and T lymphocytes overexpressing GRP78. Decreased autophagy and increased apoptosis in response to TG-induced ER stress were observed in lupus T lymphocytes. GRP78 and ER stress-signaling molecules, such as PERK, p-eIF2α, IRE1, and ATF6 decreased, whereas CHOP levels increased in lupus T cells in response to TG. The levels antiapoptotic molecules, Bcl-2 and Bcl-XL decreased, whereas the proapoptotic molecules, Bax and caspase 6, increased in lupus T cells. The TG-induced ER stress altered autophagy and apoptosis, which in turn, led to abnormal T cell homeostasis with increased apoptotic T cell death. We hypothesize that aberrant autophagy of T lymphocytes as a result of ER stress and decreased GRP78 expression is involved in the pathogenesis of SLE and might serve as important therapeutic targets.