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Objective: The aim of this study was to explore the role of cytokines in the pathogenesis of SLE in a genetically homogeneous Caucasian SLE patient population., Methods: Serum levels of the following cytokines were determined by ELISA in SLE patients (diagnosed as per ACR diagnostic criteria): IL-1β, IL-10, IL-12p70 and TNF-α. Demographic data, disease activity as per the SLEDAI and damage scores (SLICC) at the 5-year follow-up were calculated., Results: Enhanced production of TNF-α, IL-1 and IL-10 were observed in SLE patients compared with controls. A strong positive correlation was seen between levels of IL-12p70 and IL-10. In addition, IL-10, TNF-α and IL-1 demonstrated a significant relationship with disease activity. Interestingly, elevated levels of IL-10 were observed in SLE patients with CNS involvement while patients with elevated levels of TNF-α were more likely to have renal involvement and sustain damage over the follow-up period. Additionally, the ratio of all cytokines assayed to IL-12p70 levels were significantly higher in SLE patients when compared with controls, with an association seen between damage accrual and the IL-1β/IL-12p70 ratio (r = 0.431, P = 0.003), IL-10/IL-12p70 ratio (r = 0.351, P = 0.018) and TNF-α/IL-12p70 ratio (r = 0.33, P = 0.028). When the respective ratios were analysed for organ-specific disease, significant differences were observed for the IL-1β/IL-12p70 ratio (0.79 vs 0.47, P = 0.036), IL-10/IL-12p70 ratio (4.29 vs 1.87, P = 0.018) and TNF-α/IL-12p70 ratio (7.49 vs 5.21, P = 0.018) with respect to renal involvement., Conclusion: Increased levels of a number of immunomodulatory cytokines relative to IL-12p70 in this Caucasian SLE patient population are seen in patients with renal involvement and are associated with increased accrual of damage at the 5-year follow-up., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objective: To examine the role of 17β-estradiol in the regulation of the autoantigen tripartite motif-containing protein 21 (TRIM-21) in patients with systemic lupus erythematosus (SLE)., Methods: Monocytes isolated from healthy control subjects and patients with SLE were stimulated with 17β-estradiol and/or the estrogen receptor α (ERα) antagonist methyl-piperidino-pyrazole dihydrochloride. TRIM-21, ERα, and CREMα expression was determined by real-time polymerase chain reaction (PCR) analysis. MatInspector software was used to identify putative binding sites within the TRIM-21 promoter. ERα binding to the TRIM-21 gene promoter region in monocytes was analyzed by chromatin immunoprecipitation (ChIP) assay. TRIM-21 and interferon regulatory factor 3 protein levels were analyzed by Western blotting., Results: Real-time PCR analysis demonstrated a role of estrogen in the regulation of TRIM-21 expression in monocytes, which correlated positively with ERα gene expression in patients with SLE. Investigations into the human TRIM-21 promoter revealed the presence of an estrogen response element, with ChIP assays confirming ERα binding to this site. Studies into estrogen-induced TRIM-21 expression revealed a hyperresponsiveness of SLE patients to 17β-estradiol, which led to the enhanced levels of TRIM-21 observed in these individuals., Conclusion: Our results demonstrate a role of estrogen in the regulation of TRIM-21 expression through an ERα-dependent mechanism, a pathway that we observed to be overactive in SLE patients. Treatment of monocytes with an ERα antagonist abrogated estrogen-induced TRIM-21 expression and, as a consequence, decreased the expression of interleukin-23. These findings identify TRIM-21 as a novel ERα-regulated gene and provide novel insights into the link between estrogen and the molecular pathogenesis of SLE., (Copyright © 2014 by the American College of Rheumatology.)

Although production of cytokines by TLR is essential for viral and bacterial clearance, overproduction can be detrimental, thus controlling these responses is essential. CD33-related sialic acid binding Ig-like lectin receptors (Siglecs) have been implicated in the control of leukocyte responses. In this study, we report that murine Siglec-E is induced by TLRs in a MyD88-specific manner, is tyrosine phosphorylated following LPS stimulation, and negatively regulates TLR responses. Specifically, we demonstrate the Siglec-E expression inhibits TLR-induced NF-kappaB and more importantly, the induction of the antiviral cytokines IFN-beta and RANTES. Siglec-E mediates its inhibitory effects on TIR domain containing adaptor inducing IFN-beta (TRIF)-dependent cytokine production via recruitment of the tyrosine [corrected] phosphatase SHP2 and subsequent inhibition of TBK1 activity as evidenced by enhanced TBK1 phosphorylation in cells following knockdown of Siglec-E expression. Taken together, our results demonstrate a novel role for Siglec-E in controlling the antiviral response to TLRs and thus helping to maintain a healthy cytokine balance following infection.

In recent years members of the tripartite motif-containing (TRIM) family of E3 ubiquitin ligases have been shown to both positively and negatively regulate viral defence and as such are emerging as compelling targets for modulating the anti-viral immune response. In this study we identify TRIM68, a close homologue of TRIM21, as a novel regulator of Toll-like receptor (TLR)- and RIG-I-like receptor (RLR)-driven type I IFN production. Proteomic analysis of TRIM68-containing complexes identified TRK-fused gene (TFG) as a potential TRIM68 target. Overexpression of TRIM68 and TFG confirmed their ability to associate, with TLR3 stimulation appearing to enhance the interaction. TFG is a known activator of NF-κB via its ability to interact with inhibitor of NF-κB kinase subunit gamma (IKK-γ) and TRAF family member-associated NF-κB activator (TANK). Our data identifies a novel role for TFG as a positive regulator of type I IFN production and suggests that TRIM68 targets TFG for lysosomal degradation, thus turning off TFG-mediated IFN-β production. Knockdown of TRIM68 in primary human monocytes resulted in enhanced levels of type I IFN and TFG following poly(I:C) treatment. Thus TRIM68 targets TFG, a novel regulator of IFN production, and in doing so turns off and limits type I IFN production in response to anti-viral detection systems. [ABSTRACT FROM AUTHOR]

The concept that viral sensing systems, via their ability to drive pro-inflammatory cytokine and interferon production, contribute to the development of autoimmune and autoinflammatory disease is supported by a wide range of clinical and experimental observations. Recently, the tripartite motif-containing proteins (TRIMs) have emerged as having key roles in antiviral immunity - either as viral restriction factors or as regulators of pathways downstream of viral RNA and DNA sensors, and the inflammasome. Given their involvement in these pathways, we propose that TRIM proteins contribute to the development and pathology of autoimmune and autoinflammatory conditions, thus making them potential novel targets for therapeutic manipulation. [ABSTRACT FROM AUTHOR]

The article offers information on the role of MHC molecules and Toll like receptors (TLRs) in the immune system of human body. It states that TLRs are inherited immune receptors that causes the production of inflammatory cytokines. It also mentions about the importance of a nonreceptor tyrosine kinase, Bruton's tyrosine kinase (Btk) for immune response.

CD33-related Siglecs (sialic acid-binding immunoglobulin-like lectins) 5–11 are inhibitory receptors that contain a membrane proximal ITIM (immunoreceptor tyrosine-based inhibitory motif) (I/V/L/)XYXX(L/V), which can recruit SHP-1/2. However, little is known about the regulation of these receptors. SOCS3 (suppressor of cytokine signaling 3) is up-regulated during inflammation and competes with SHP-1/2 for binding to ITIM-like motifs on various cytokine receptors resulting in inhibition of signaling. We show that SOCS3 binds the phosphorylated ITIM of Siglec 7 and targets it for proteasomal-mediated degradation, suggesting that Siglec 7 is a novel SOCS target. Following ligation, the ECS E3 ligase is recruited by SOCS3 to target Siglec 7 for proteasomal degradation, and SOCS3 expression is decreased concomitantly. In addition, we found that SOCS3 expression blocks Siglec 7-mediated inhibition of cytokine-induced proliferation. This is the first time that a SOCS target has been reported to degrade simultaneously with the SOCS protein and that inhibitory receptors have been shown to be degraded in this way. This may be a mechanism by which the inflammatory response is potentiated during infection. [ABSTRACT FROM AUTHOR]