Cell Activation In Systemic Lupus Erythematosus Research Articles

Mitochondrial Lon protease promotes CD4+ T cell activation by activating the cGAS-STING-TBK1 axis in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease in which autoreactive CD4+ T cells play an essential role. We extracted CD4+ T cells from SLE-prone Fcgr2b-/- mice to elaborate the mechanism of mitochondrial Lon protease in CD4+ T cell activation in SLE. Transcriptome sequencing was performed in SLE-prone Fcgr2b-/- mice, and the stimulator of interferon gene (STING) related to SLE was obtained. It was demonstrated that STING expression was elevated in CD4+ T cells in SLE-prone Fcgr2b-/- mice. The downstream genes and pathways of STING were predicted by GO and KEGG approaches. The data indicated that STING regulated IFN signaling to promote CD4+ T cell activation in SLE-prone Fcgr2b-/- mice. Next, the interaction of cGAS, STING, TBK1, and IFN-I was verified by Co-IP assay. Moreover, the roles of cGAS, STING, and TBK1 in activating CD4+ T cells from SLE-prone Fcgr2b-/- mice were evaluated using gain- or loss-of-function experiments. Mechanistically, cGAS upregulated the IFN-I signaling pathway by directly interacting with STING and TBK1, contributing to CD4+ T cell activation. Besides, cytosolic mtDNA could activate CD4+ T cell activation in SLE-prone Fcgr2b-/- mice by upregulating the cGAS-STING-TBK1 axis. The function of mitochondrial Lon protease in oxidative damage and mtDNA release in CD4+ T cells of SLE-prone Fcgr2b-/- mice were explored. Mitochondrial Lon protease enhanced mtDNA release into the cytoplasm under oxidative stress. Collectively, our work indicates that mitochondrial Lon protease enhances CD4+ T cell activation by inducing mtDNA leakage and offers new candidate targets for developing diagnostic and therapeutic strategies.

Subclinical Corneal Nerve Fiber Damage and Immune Cell Activation in Systemic Lupus Erythematosus: A Corneal Confocal Microscopy Study.

PurposeThe purpose of this study was to evaluate the utility of corneal confocal microscopy (CCM) in identifying small nerve fiber damage and immune cell activation in patients with systemic lupus erythematosus (SLE).MethodsThis cross-sectional comparative study included 39 consecutive patients with SLE and 30 healthy control participants. Central corneal sensitivity was assessed using a Cochet-Bonnet contact corneal esthesiometer and a laser scanning CCM (Heidelberg, Germany) was used to quantify corneal nerve fiber density (CNFD), nerve branch density (CNBD), nerve fiber length (CNFL), and Langerhans cell (LC) density.ResultsAge was comparable among patients with SLE (33.7 ± 12.7) and controls (35.0 ± 13.7 years, P = 0.670) and the median duration of disease was 3.0 years (2.0–10.0 years). CNBD (P = 0.003) and CNFL (P = 0.019) were lower and mature LC density (P = 0.002) was higher, but corneal sensitivity (P = 0.178) and CNFD (P = 0.198) were comparable in patients with SLE compared with controls. The SELENA-SLEDAI score correlated with CNFD (ρ = −0.319, P = 0.048) and CNFL (ρ = −0.373, P = 0.019), and the total and immature LC densities correlated with CNBD (ρ = −0.319. P = 0.048, and ρ = −0.328, P = 0.041, respectively). Immature LC density was higher (P = 0.025), but corneal sensitivity and nerve fiber parameters were comparable between patients with (33%) and without neuropsychiatric symptoms and SLE.ConclusionsCorneal confocal microscopy identifies distal corneal nerve fiber loss and increased immune cell density in patients with SLE and corneal nerve loss was associated with disease activity.Translational RelevanceCorneal confocal microscopy may enable the detection of subclinical corneal nerve loss and immune cell activation in SLE.

Updates on Clinical Trials in Systemic Lupus Erythematosus.

Because of the complexity of systemic lupus erythematosus (SLE), different approaches are undertaken while investigating potential therapeutic compounds to treat the disease. The purpose of this review is to summarize the results from recent clinical trials, which investigated different compounds for treating SLE. Targeting B cells and type I interferons constitutes the major focus in recent clinical trials. The potential for therapeutic effects of small molecule inhibition such as JAK, Tyk, and Btk is now being investigated for treating SLE. The immunoregulation of T cell activation in SLE is studied using low-dose IL-2 and CD40 ligand inhibition. There are clinical trials that study bispecific antibodies, with binding specificities for 2 different target molecules related to T- and B-cell activation or to different aspects of B cell activation. An approach of combination treatment is also being studied. Clinical trials are underway and new treatment compounds for SLE are being anticipated.

LncRNA GAS5 suppresses CD4+ T cell activation by upregulating E4BP4 via inhibiting miR-92a-3p in systemic lupus erythematosus

Increasing evidence reveals that long noncoding RNAs (lncRNAs) are associated with autoimmune and inflammatory diseases, such as systemic lupus erythematosus (SLE). In this study, we aimed to explore the role of lncRNA growth arrest specific 5 (GAS5) in the pathogenesis of SLE. We found that lncRNA GAS5 was decreased in CD4+ T cells and plasma from SLE patients. Overepression of GAS5 inhibited activation of normal CD4+ T cells and attenuated the self-reactivity of SLE CD4+ T cells. Additionally, we demonstrated that adenovirus E4 binding protein 4 (E4BP4) was involved in lncRNA GAS5-mediated inhibition of CD4+ T cell activation. GAS5 could upregulate E4BP4 by inhibiting miR-92a-3p. Taken together, our results indicate that the GAS5/miR-92a-3p/E4BP4 pathway plays an important role in inhibiting CD4+ T cell activation in SLE, thus providing a potential therapeutic target for SLE treatment.

Selective Histone Deacetylase 6 Inhibition Normalizes B Cell Activation and Germinal Center Formation in a Model of Systemic Lupus Erythematosus.

Autoantibody production by plasma cells (PCs) plays a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE). The molecular pathways by which B cells become pathogenic PC secreting autoantibodies in SLE are incompletely characterized. Histone deactylase 6 (HDAC6) is a unique cytoplasmic HDAC that modifies the interaction of a number of tubulin- associated proteins; inhibition of HDAC6 has been shown to be beneficial in murine models of SLE, but the downstream pathways accounting for the therapeutic benefit have not been clearly delineated. In the current study, we sought to determine whether selective HDAC6 inhibition would abrogate abnormal B cell activation in SLE. We treated NZB/W lupus mice with the selective HDAC6 inhibitor, ACY-738, for 4 weeks beginning at 20 weeks-of age. After only 4 weeks of treatment, manifestation of lupus nephritis (LN) were greatly reduced in these animals. We then used RNAseq to determine the genomic signatures of splenocytes from treated and untreated mice and applied computational cellular and pathway analysis to reveal multiple signaling events associated with B cell activation and differentiation in SLE that were modulated by HDAC6 inhibition. PC development was abrogated and germinal center (GC) formation was greatly reduced. When the HDAC6 inhibitor-treated lupus mouse gene signatures were compared to human lupus patient gene signatures, the results showed numerous immune, and inflammatory pathways increased in active human lupus were significantly decreased in the HDAC6 inhibitor treated animals. Pathway analysis suggested alterations in cellular metabolism might contribute to the normalization of lupus mouse spleen genomic signatures, and this was confirmed by direct measurement of the impact of the HDAC6 inhibitor on metabolic activities of murine spleen cells. Taken together, these studies show HDAC6 inhibition decreases B cell activation signaling pathways and reduces PC differentiation in SLE and suggest that a critical event might be modulation of cellular metabolism.

Distinct Effector B Cells Induced by Unregulated Toll-like Receptor 7 Contribute to Pathogenic Responses in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is characterized by B cells lacking IgD and CD27 (double negative; DN). We show that DN cell expansions reflected a subset of CXCR5- CD11c+ cells (DN2) representing pre-plasma cells (PC). DN2 cells predominated in African-American patients with active disease and nephritis, anti-Smith and anti-RNA autoantibodies. They expressed a T-bet transcriptional network; increased Toll-like receptor-7 (TLR7); lacked the negative TLR regulator TRAF5; and were hyper-responsive to TLR7. DN2 cells shared with activated naive cells (aNAV), phenotypic and functional features, and similar transcriptomes. Their PC differentiation and autoantibody production was driven by TLR7 in an interleukin-21 (IL-21)-mediated fashion. An invivo developmental link between aNAV, DN2 cells, and PC was demonstrated by clonal sharing. This study defines a distinct differentiation fate of autoreactive naive B cells into PC precursors with hyper-responsiveness to innate stimuli, as well as establishes prominence of extra-follicular B cell activation in SLE, and identifies therapeutic targets.

Defective BTLA functionality is rescued by restoring lipid metabolism in lupus CD4+ T cells.

Coinhibitory receptors play an important role in the prevention of autoimmune diseases, such as systemic lupus erythematosus (SLE), by limiting T cell activation. B and T lymphocyte attenuator (BTLA) is an inhibitory receptor, similar to cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed death 1 (PD1), that negatively regulates the immune response. The role of BTLA in the pathogenesis of autoimmune diseases in humans and, more specifically, in SLE is largely unknown. We investigated BTLA expression on various T cell subsets, and we did not observe significant variations of BTLA expression between lupus patients and healthy controls. However, the enhancement of BTLA expression after activation was significantly lower in SLE patients compared with that in healthy controls. Furthermore, we found an impaired capacity of BTLA to inhibit T cell activation in SLE due to a poor BTLA recruitment to the immunological synapse following T cell stimulation. Finally, we demonstrated that defective BTLA function can be corrected by restoring intracellular trafficking and by normalizing the lipid metabolism in lupus CD4+ T cells. Collectively, our results evidence that the BTLA signaling pathway is altered in SLE T cells and highlight the potential of targeting this pathway for the development of new therapeutic strategies in lupus.

New insights into B cell biology in systemic lupus erythematosus and Sjögren's syndrome.

Our understanding of the physiological and pathogenic functions of B cells in systemic lupus erythematosus (SLE) and Primary Sjögren's syndrome (pSS) continues to expand. In this review, we discuss novel insights published in the last 18 months into the roles of B cells in systemic autoimmunity. Data have continued to expand regarding the diverse mechanisms by which innate immune signals including Toll-like receptors (TLRs) regulate the B cell compartment. Localized B cells and long-lived plasma cells have been identified as playing an important role in target tissue including the development of ectopic lymphoid structures in kidney and salivary gland. In addition to pathogenic roles for B cells, there is mounting evidence for regulatory B cell subsets that play a protective role and new insights into the signals that regulate their development. The past few years have provided insights into the multiple paths by which innate immune signals can lead to B cell activation in SLE and pSS and the increasingly diverse ways in which B cells contribute to disease expression. Further understanding the imbalance between protective and pathogenic functions for B cells in disease including in understudied target tissue should yield new treatment approaches.

New possibilities of pharmacotherapy for systemic lupus erythematosus: A place of belimumab

Systemic lupus erythematosus (SLE) is a multifactorial disease caused by complex interactions between the genetic and environmental factors underlying various innate and adaptive immunity disorders, including cytokine hyperproduction, abnormal B cell activation, impaired intracellular T-cell signaling, and defective apoptotic and necrotic cell clearance. A broad spectrum of genetic disorders associated with susceptibility to the disease and/or its definite variants has been identified. Our knowledge concerning the mechanisms of polyclonal B cell activation in SLE has advanced substantially. Various defects in the T cells regulating a B cell immune response have been detected. The development of genetic, epigenomic, transcriptomic, and proteomic technologies could identify a group of pathogenetically relevant cytokines, including BLyS (the B-lymphocyte stimulator is the most important component of cytokine-mediated regulation of B cell function, proliferation, and differentiation), interleukin (IL) 6, 17, 18, type 1 interferon, and tumor necrosis factor- α , which are involved in the development of visceral inflammation and damage. Large-scale clinical trials of different medications, primarily biological agents (BA), were conducted in patients with SLE. Rituximab (RTM) is the first BA to be used to treat this disease. Despite its official registration for the therapy of SLE, RTM is included in the EULAR, ACR, and Russia's Association of Rheumatologists guidelines for its treatment. Belimumab, a fully human recombinant IgG1λ monoclonal antibody, specially designed to treat SLE, prevents the interaction of pBLyS with the receptors of autoreactive transitional and naive B cells, giving rise to the suppression of B cell hyperresponsiveness, autoantibody synthesis in particular. In addition, BLyS block may cause decreased survival of B cells in the germinal centers of lymphoid organs, differentiation of memory B cells into autoantibody-producing cells, and synthesis of proinflammatory cytokines (IL-21, IL-17, and others) that play an important role in the immunopathogenesis of SLE. Despite its moderate efficacy, belimumab will be able to improve pharmacotherapy for this disease.

APRIL levels strongly correlate with IL-17 in systemic lupus erythematosus.

Activated self-reactive B cells play an important part in systemic lupus erythematosus (SLE). A proliferation-inducing ligand (APRIL) and B cell-activating factor (BAFF) are B-cell specific stimulators, but activate B cells through different receptors. We investigated the reciprocal association between serum APRIL (s-APRIL), serum BAFF (s-BAFF) and immunological and clinical findings in SLE patients. A cross-sectional case-control study was performed in 100 SLE patients (87% female, age 49 years, disease duration 12 years). APRIL and BAFF levels were measured by sandwich ELISA, compared with healthy controls and correlated with autoantibody, cytokine (IL-6 and IL-17) and clinical findings through nonparametric and multivariate regression analyses. Both median s-APRIL (478 vs. 0 pg/ml, p = 0.01) and s-BAFF (1720 vs. 0.9 pg/ml, p < 0.001) were higher in SLE patients than controls. Increased s-BAFF was observed in 86% of patients, while s-APRIL was increased only in 17% (p < 0.01). S-APRIL correlated with s-BAFF in controls (p = 0.04), but not in SLE (p = 0.8). Increased s-APRIL was strongly and independently associated with IL-17 activation (p < 0.001), while increased s-BAFF levels were associated with anti-nucleosome antibody presence (p = 0.001). Disease activity and organ damage were associated with s-BAFF but not s-APRIL. While both s-BAFF and s-APRIL levels are elevated in SLE patients, they reflect different immunologic and clinical pathways. The strong association between s-APRIL and IL-17 activation supports a role for Th17 helper cells in B cell activation in SLE.

Proinflammatory cytokines (TNF-α and IL-6) in Egyptian patients with SLE: Its correlation with disease activity

Background Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by a wide variety of autoantibodies, some of which are pathogenic. In recent years it has become more evident that the polyclonal B cell activation in SLE is T-cell dependent. The stimulation of the autoantibody producing B cells is likely mediated by the TH2 subtype of T cells producing IL-4, IL-5, IL-6 and IL- 10, whereas the TH1 subtype secreting IL-2 and IFN-γ predominates in cell-mediated immune response. Tumor Necrosis Factor (TNF-α) is both a proinflammatory and an immunoregulatory cytokine. TNF-α has differential effects on B cells, on T cells and on dendritic cells as well as on the process of programmed cell death. Understanding how the immune system integrates the pleiotropic properties of TNF-α is a challenge, particularly so in diseases like SLE. Meanwhile the role of IL-6 in the pathogenesis of SLE is controversial. Objective: To investigate whether serum levels of TNF-α and IL-6 is higher in Egyptian patients with SLE than healthy control volunteers and its correlation with the clinical activity in patients with different activity scores as measured by Systemic Lupus Erythmatosus Disease Activity Index (SLEADI). Methods: Sixty individuals (40 patients with Systemic lupus Erythmatosus and 20 healthy control volunteers) were the subject of this study, they were subjected to thorough clinical examination, laboratory investigations, their clinical disease activity was scored according to SLEDAI, and serum sampling was obtained for TNF-α and IL-6 levels assay. Renal biopsy was carried out and examined by light microscopy by a pathologist blinded with the clinical activity. Results: The mean level of TNF-α was (766.95 ± 357.82 Pg/ml) for patients with active disease while it was (314.01 ± 100.87 Pg/ml) for those with inactive disease and (172.7 ± 39.19 Pg/ml) for the healthy control group. The difference was statistically significant ( P = .002). The mean level of IL-6 was (135.4 ± 54.23 Pg/ml) for patients with active disease while it was (47.33 ± 18.61 Pg/ml) for those with inactive disease and (21.15 ± 10.99 Pg/ml) for the healthy control group. The difference was statistically significant ( P = .002). A significant correlations between TNF-α and IL-6 serum levels and the SLEDAI score was observed ( r = .743 and .772, respectively). Conclusion: Serum TNF-α and IL-6 are sensitive markers of SLE disease activity. They may be useful independent markers for prediction of SLE disease activity and to differentiate normal subjects from those having SLE. Possible therapeutic implications in the treatment of SLE in the future deserve wide scale trials.

Expression and function of inducible co-stimulator in patients with systemic lupus erythematosus: possible involvement in excessive interferon-γ and anti-double-stranded DNA antibody production

Inducible co-stimulator (ICOS) is the third member of the CD28/cytotoxic T-lymphocyte associated antigen-4 family and is involved in the proliferation and activation of T cells. A detailed functional analysis of ICOS on peripheral blood T cells from patients with systemic lupus erythematosus (SLE) has not yet been reported. In the present study we developed a fully human anti-human ICOS mAb (JTA009) with high avidity and investigated the immunopathological roles of ICOS in SLE. JTA009 exhibited higher avidity for ICOS than a previously reported mAb, namely SA12. Using JTA009, ICOS was detected in a substantial proportion of unstimulated peripheral blood T cells from both normal control individuals and patients with SLE. In CD4+CD45RO+ T cells from peripheral blood, the percentage of ICOS+ cells and mean fluorescence intensity with JTA009 were significantly higher in active SLE than in inactive SLE or in normal control individuals. JTA009 co-stimulated peripheral blood T cells in the presence of suboptimal concentrations of anti-CD3 mAb. Median values of [3H]thymidine incorporation were higher in SLE T cells with ICOS co-stimulation than in normal T cells, and the difference between inactive SLE patients and normal control individuals achieved statistical significance. ICOS co-stimulation significantly increased the production of IFN-γ, IL-4 and IL-10 in both SLE and normal T cells. IFN-γ in the culture supernatants of both active and inactive SLE T cells with ICOS co-stimulation was significantly higher than in normal control T cells. Finally, SLE T cells with ICOS co-stimulation selectively and significantly enhanced the production of IgG anti-double-stranded DNA antibodies by autologous B cells. These findings suggest that ICOS is involved in abnormal T cell activation in SLE, and that blockade of the interaction between ICOS and its receptor may have therapeutic value in the treatment of this intractable disease.

Proinflammatory Cytokines (TNF alpha and IL-6) in Egyptian SLE Patients With Lupus Nephritis

Aim: Systemic Lupus Erythematosus (SLE) is an autoimmune disease characterized by a wide variety of autoantibodies, some of which are pathogenic. In recent years it has become more evident that the polyclonal B cell activation in SLE is T-cell dependent. To investigate whether serum levels of TNF-α and IL-6 is higher in Egyptian patients with SLE- presented with lupus nephritis -than healthy control volunteers and its correlation with the clinical activity in patients with different activity scores as measured by Systemic Lupus Erythmatosus Disease Activity Index (SLEADI). Methods: Sixty individuals (40 patients with SLE and 20 healthy control volunteers) were the subject of this study, they were subjected to thorough clinical examination, laboratory investigations, their clinical disease activity was scored according to SLEDAI, and serum sampling was obtained for TNF-α and IL-6 levels assay. Renal biopsy was carried out for all patients. Results: The mean level of TNF-α was (766.95±357.82 ρg/ml) for patients with active disease while it was (314.01±100.87ρg/ml) for those with inactive disease -the difference was statistically significant (p=0.002), and (172.7±39.19ρg/ml) for the healthy control group. The mean level of IL-6 was (135.4±54.23ρg/ml) for patients with active disease while it was (47.33±18.61ρg/ml) for those with inactive disease - the difference was statistically significant (p=0.002), and (21.15±10.99ρg/ml) for the healthy control group. A significant correlations between TNF-α and IL-6 serum levels and the SLEDAI score was observed (r =0.743 and 0.772 respectively). Conclusion: Serum TNF-α and IL-6 are sensitive markers for SLE disease activity. They may be useful independent markers for prediction of SLE disease activity and to differentiate normal subjects from those having SLE. Their possible therapeutic implications in the treatment of SLE in the future deserve wide scale trials.

Correlation between CD29 density on CD8 + lymphocytes and serum IgG in systemic lupus erythematosus

The purpose of this paper is to establish whether there is increased lymphocyte adhesion molecule density in systemic lupus erythematosus (SLE), which could alter the migration pathways and activation thresholds of lymphocytes and thus contribute to the pathogenesis of the disease. We analysed the CD11a, CD29 and CD2 bound antibody molecule (bam) density on the CD4+ and CD8+ CAMhigh (primed) lymphocytes of 28 SLE patients (8 active and 20 inactive by BILAG), using reproducible flow cytometric measurements, standardized with fluorescent beads and antibodies of known fluorescein: protein ratios. In a second patient cohort (17 patients), we investigated whether CD29 density on CD8+ cells correlated with measures of humoral (serum IgG) or cellular (urine neopterin) activation. In the first cohort, 36% of patients had elevated CD29 (beta 1 integrin) density on CD8+ cells. In the second cohort, CD29 density on CD8+ cells was found to be closely associated with total plasma IgG (r = 0.71, P = 0.001), but not with urine neopterin, disease activity (BILAG) or drug treatment. We conclude that CD29 on CD8+ cells is associated with B cell activation in SLE.