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Objective Effector CD8+ T cell function is impaired in systemic lupus erythematosus (SLE) and is associated with a compromised ability to fight infections. Signaling lymphocytic activation molecule family member 7 (SLAMF7) engagement has been shown to enhance natural killer cell degranulation. This study was undertaken to characterize the expression and function of SLAMF7 on CD8+ T cell subsets isolated from the peripheral blood of SLE patients and healthy subjects. Methods CD8+ T cell subset distribution, SLAMF7 expression, and expression of cytolytic enzymes (perforin, granzyme A [GzmA], and GzmB) on cells isolated from SLE patients and healthy controls were analyzed by flow cytometry. CD107a expression and interferon-γ (IFNγ) production in response to viral antigenic stimulation in the presence or absence of an anti-SLAMF7 antibody were assessed by flow cytometry. Antiviral cytotoxic activity in response to SLAMF7 engagement was determined using a flow cytometry-based assay. Results The distribution of CD8+ T cell subsets was altered in the peripheral blood of SLE patients, with a decreased effector cell subpopulation. Memory CD8+ T cells from SLE patients displayed decreased amounts of SLAMF7, a surface receptor that characterizes effector CD8+ T cells. Ligation of SLAMF7 increased CD8+ T cell degranulation capacity and the percentage of IFNγ-producing cells in response to antigen challenge in SLE patients and healthy controls. Moreover, SLAMF7 engagement promoted cytotoxic lysis of target cells in response to stimulation with viral antigens. Conclusion CD8+ T cell activation in response to viral antigens is defective in SLE patients. Activation of SLAMF7 through a specific monoclonal antibody restores CD8+ T cell antiviral effector function to normal levels and thus represents a potential therapeutic option in SLE. [ABSTRACT FROM AUTHOR]

Objective Imbalanced cytokine production by T cells characterizes both patients with systemic lupus erythematosus (SLE) and lupus-prone mice and contributes to immune dysregulation. This study was undertaken to further investigate in detail the production of interleukin-2 (IL-2), interferon-γ (IFNγ), IL-4, and IL-17A by CD4+ cell subsets in healthy subjects and patients with SLE, and the signaling response of CD4+ T cells in response to exogenous IL-2. Methods Cytokine production by differentiated subsets of CD4+ T cells was assessed by intracellular staining following stimulation with phorbol myristate acetate and ionomycin and by enzyme-linked immunosorbent assay after anti-CD3/anti-CD28 stimulation. The IL-2 signaling pathway was examined by assessing JAK-3/STAT-5 phosphorylation. Cell proliferation in response to IL-2 was examined by carboxyfluorescein succinimidyl ester dilution. Results Production of IL-2 was defective primarily among naive CD4+ T cells, whereas the production of IFNγ, IL-4, and IL-17A was not significantly different between patients with SLE and healthy subjects. JAK-3/STAT-5 phosphorylation and proliferation of CD4+ T cells from SLE patients in response to exogenous IL-2 were impaired compared to cells from healthy subjects. Conclusion These data suggest that altered IL-2 production, as well as impaired IL-2-mediated signaling and proliferative responses, characterize SLE CD4+ T cells. Our data demonstrate the need for caution in designing IL-2 treatment trials for patients with SLE. Approaches to restore CD4+ T cell sensitivity to IL-2 should be considered. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The costimulatory receptor Slamf6 partially controls lupus‐related autoimmunity in congenic Sle1b mice; for instance, the presence of the protein isoform Slamf6‐H1 in Sle1b.Slamf6‐H1 mice mitigates disease. Here, we report that young Sle1b mice, but not Sle1b.Slamf6‐H1 or B6 mice, contain a memory T‐helper cell subset identified by ∗∗∗[mt]2‐fold increase in expression of 17 genes, chief among which is Spp1, encoding the cytokine osteopontin (OPN). These T follicular helper (TFH) cells, including OPN+TFH cells, expand concomitantly with severity of the disease. By contrast, Sle1b.Slamf6‐H1 or Sle1b.SAP–/– mice do not develop autoantibodies and the number of TFH cells is 5 times lower than in age‐matched Sle1b mice. By comparing Sle1b and Sle1b.OPN–/– mice, we find that the lack of OPN expression impedes early autoantibody production. Furthermore, on the adoptive transfer of Sle1b.OPN–/– CD4+ T cells into bm12 recipients autoantibody production and germinal center formation is reduced compared to recipients of Sle1b.OPN+/+ CD4+ T cells. We propose a model in which OPN provides a survival signal for a precursor TFH cell subset, which is a key factor in autoimmunity. Keszei, M., Detre, C., Castro, W., Magelky, E., O'Keeffe, M., Kis‐Toth, K., Tsokos, G. C., Wang, N., Terhorst, C. Expansion of an osteopontin‐expressing T follicular helper cell subset correlates with autoimmunity in B6.Sle1b mice and is suppressed by the H1‐isoform of the Slamf6 receptor. FASEB J. 27, 3123–3131 (2013). www.fasebj.org [ABSTRACT FROM AUTHOR]

Objective To identify microRNAs (miRNAs) in human T cells that can explain known antiinflammatory properties of steroids. Methods Activated human CD4+ T cells from healthy donors were exposed to 1 μ M methylprednisolone (MP) in vitro and then subjected to miRNA and messenger RNA microarray analyses. Changes in expression profiles were recorded. Using quantitative polymerase chain reaction (qPCR), flow cytometry, and enzyme-linked immunosorbent assay (ELISA), we confirmed the suppression of predicted targets, and through miRNA transfection experiments, we could suggest mechanistic links. Results We identified numerous steroid-responsive genes and miRNAs-many known and some novel-including multiple previously unknown proinflammatory genes suppressed by MP. Further studies using qPCR, flow cytometry, and ELISA demonstrated that methylprednisolone increased the expression of miRNA-98 (miR-98) and suppressed the levels of predicted targets, including interleukin-13 and 3 tumor necrosis factor receptors (TNFRs): Fas, FasL, and TNFR superfamily member 1B. Forced expression of miR-98 in T cells resulted in suppression of the same targets. Conclusion The findings of this study demonstrate a link between miR-98 expression and the effects of MP and provide evidence suggesting that MP acts through miR-98 to inhibit specific proinflammatory targets. Identification of this antiinflammatory mechanism of glucocorticoids is important, since it may pave the way toward the elusive goal of dissociating adverse effects from therapeutic effects. [ABSTRACT FROM AUTHOR]

Objective T cells from patients with systemic lupus erythematosus (SLE) display increased amounts of spleen tyrosine kinase (Syk), which is involved in the aberrant CD3/T cell receptor-mediated signaling process, and increased amounts of CREMα, which suppresses the production of interleukin-2. Syk expression can be suppressed by CREMα. This study was undertaken to investigate why CREMα fails to suppress Syk expression in SLE T cells. Methods CREMα was overexpressed in healthy T cells by transfection with CREMα expression vector, and Syk expression and phosphorylation were measured. A newly identified cAMP response element (CRE) site on the SYK promoter was characterized by chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay. The CREMα-mediated repression of Syk expression was further evaluated by analyzing SYK promoter activity. T cells from SLE patients and healthy individuals were subjected to ChIP to evaluate CREMα binding and histone H3 acetylation. Results Increased CREMα levels suppressed Syk expression by direct binding to a CRE site of the SYK promoter in T cells from healthy individuals but failed to do so in T cells from SLE patients. The failure of CREMα to suppress Syk expression in SLE T cells was due to weaker binding to the CRE site of the SYK promoter compared to healthy T cells because the promoter site is hypoacetylated in SLE T cells and therefore of limited access to transcription factors. Conclusion Our findings indicate that epigenetic alteration of the SYK promoter in SLE T cells results in the inability of the transcriptional repressor CREMα to bind and suppress the expression of Syk, resulting in aberrant T cell signaling. [ABSTRACT FROM AUTHOR]

The article talks about a study conducted to determine whether inhibition of calcium/calmodulin-dependent protein kinase type IV (CaMKIV) would improve systemic lupus erythematosus (SLE), which can be treated by the use of indiscriminate immunosuppression. The data was collected with KN-93, a CaMKIV inhibitor on MRL/lpr mice by evaluating the impact of lessening of CAMK4 on interferon-γ (IFN-γ) expression by human SLE T cells.

OBJECTIVE: To investigate whether genetic preponderance of a T cell receptor (TCR) recognizing an arthritogenic peptide of human cartilage proteoglycan (PG) is sufficient for development of arthritis. METHODS: We performed a longitudinal study using BALB/c mice expressing a TCR that recognizes the arthritogenic ATEGRVRVNSAYQDK peptide of human cartilage PG. PG-specific TCR-transgenic (PG-TCR-Tg) mice were inspected weekly for peripheral arthritis until 12 months of age. Peripheral joints were examined histologically, and T cell responses, T cell activation markers, serum cytokines, and autoantibodies were measured. Apoptosis and signaling studies were performed in vitro on T cells from aged PG-TCR-Tg mice. RESULTS: Spontaneous arthritis developed as early as 5-6 months of age, and the incidence increased to 40-50% by 12 months of age. Progressive inflammation began with cartilage and bone erosions in the interphalangeal joints, and later expanded to the proximal joints of the front and hind paws. Spontaneous arthritis was associated with a high proportion of activated CD4+ T cells, enhanced interferon-[gamma] and interleukin-17 (IL-17) production, and elevated levels of serum autoantibodies. PG-TCR-Tg mice lacking IL-4 developed arthritis earlier and at a higher incidence than IL-4-sufficient mice. Antigen-specific activation-induced cell death was diminished in vitro in CD4+ T cells of PG-TCR-Tg mice with spontaneous arthritis, especially in those lacking IL-4. CONCLUSION: The presence of CD4+ T cells expressing a TCR specific for an arthritogenic PG epitope is sufficient to trigger spontaneous autoimmune inflammation in the joints of BALB/c mice. IL-4 appears to be a negative regulator of this disease, through attenuation of activation-induced cell death. [ABSTRACT FROM AUTHOR]

This article discusses a study on the effects of proinflammatory cytokine treatment or the complete absence of select cytokines on the expression of RANKL and osteoprotegerin (OPG) in synovial fibroblasts. The study used proinflammatory cytokines or antiosteoclastogenic cytokines in stimulating fibrolasts. It showed higher levels of RANKL and OPG expressed by fibroblasts from rheumatoid and arthritic joints in mice.

Background/Purpose: MicroRNA (miRNA, miR) are short RNA species (20-23 nt) that act post-transcriptionally modulating messenger RNA (mRNA) translation or stability. They control many biological processes including cell differentiation and homeostasis. Abnormal levels of miRNA have been implicated in cancers and autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. Steroids are first line anti-inflammatory medications that act through transcriptional or posttranscriptional gene regulation. In multiple instances steroids cause mRNA destabilization indicating a potential role for miRNA. Previously, using high-throughput microarray analysis, we found that methylprednisolone (MP) decreased miR-155 expression in CD4+ T cells in vitro. miR-155 is highly expressed in immune cells and influential in cell differentiation. This influence may in part be mediated through suppression of cytokine signaling 1 (SOCS1), a known target of miR-155. SOCS1 inhibits multiple JAK/STAT pathways, which may inhibit cell proliferation and differentiation. Steroids have also been shown to inhibit proliferation, differentiation and the JAK/STAT pathways. Steroids through blocking the IL-12/STAT4 pathway inhibit Th1 differentiation. This pathway is in part controlled by SOCS1, which should be under the control of miR-155. Following our previous work here we explore the potential mechanism of action of miR-155 during MP treatment of T cells. Methods: Total or naive CD4+ T cells were isolated from peripheral blood of healthy donors and activated by anti-CD3/anti-CD28 antibodies for up to 5 days with or without Th1 polarizing conditions (10 nM IL-12 and 5 mM anti-IL-4 neutralizing antibody) and with or without exposure to 10−6 M of methylprednisolone. Some cells were first transfected with mimic miR-155, control mimic miR, anti-miR-155, or control anti-miR by electroporation. Effects on miR-155, SOCS1, STAT phosphorylation, IFNg production and Th1 differentiation were monitored using flow cytometry, RNA quantification by PCR, and protein quantification by ELISA or western blot analysis. Results: Activated T cells treated with MP decrease miR-155 expression and increase SOCS1 expression. In turn, SOCS1 decreases JAK/STAT signaling and inhibits response to cytokines, notably IL-12, resulting in decreased IFNg production by activated T cells. Conclusion: We found that the anti-inflammatory effects of MP, at least in part, act through decreasing miR-155 in T cells by inhibiting JAK/STAT signaling and cytokine production through modulating SOCS1 expression. Based on our findings we propose that miR-155 inhibition could be utilized to suppress inflammation without the myriad of side effects currently inherent in chronic steroid therapy. [ABSTRACT FROM AUTHOR]