Blocking of interferon regulatory factor 1 reduces tumor necrosis factor α-induced interleukin-18 bioactivity in rheumatoid arthritis synovial fibroblasts by induction of interleukin-18 binding protein a: Role of the nuclear interferon regulatory factor 1 (original) (raw)
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Role of interferon regulatory factor-1 in the regulation of IL-18 production and activity
European Journal of Immunology, 2001
Interferon regulatory factor-1 (IRF-1) is a transcription factor regulating the expression of several cytokines. Using IRF-1 knockout (KO) mice, the role of IRF-1 in the production and activity of IL-18 was evaluated. Administration of IL-12 or concanavalin A significantly increased levels of circulating IL-18 in wild-type (WT), but not in IRF-1 KO mice. However, despite these differences in circulating IL-18 levels, no or only minor differences in constitutive or inducible IL-18 mRNA and tissue-associated protein levels were observed between WT and IRF-1 KO mice. On the other hand, we observed that constitutive and inducible levels of the IL-18-processing enzyme caspase-1 were markedly reduced in the spleen and the liver of IRF-1 KO compared to WT mice. In addition, both constitutive and inducible liver mRNA levels for the IL-18 binding protein (IL-18BP), a specific IL-18 antagonist, were significantly lower in IRF-1 KO than in WT mice. Compared to IL-12, IL-18 only weakly induced IRF-1 mRNA in cultured splenocytes. However, IL-18-induced IFN-+ production was strongly reduced in splenocytes from IRF-1 KO compared to WT cells. In conclusion, IRF-1 regulates IL-18 production and activity mostly by modulating expression of caspase-1 and IL-18BP. In addition, IRF-1 participates in the induction of IFN-+ by IL-18.
The Anti-Inflammatory properties of interleukin 18 binding protein in rheumatoid arthritis
Sudan journal of medical sciences, 2009
Objectives: Interleukin-18 binding protein (IL-18BP) is functioning as a natural anti-inflammatory and immunosuppressive molecule by neutralizing the effects of IL-18 during inflammation. This study aimed to identify the role of IL-18BPa in the regulation of immune responses associated with the pathogenesis of RA. Materials and Methods: 65 RA patients, 22 OA patients, and 40 sex and age matched healthy donors were enrolled in this study. Synovial specimens were obtained through synovectomy or arthroscopic procedures. SFMC and PBMC were prepared by using Ficoll-Hypaque separation procedure. Superarray analysis was used to measure the expression profile of immune-related genes in normal PBMC treated with recombinant human IL-18BPa.The mRNA levels of Th1 and Th2 cytokines were measured by Real-time PCR, and the protein levels of IFN-γ, IL-4 were detected by ELISA. Results: SuperArray analysis of immune related gene expression profile in normal PBMC treated with IL-18BPa indicated decreases in the gene expression of IFN-γ and its regulatory molecules STAT-1 and STAT-2. This study pointed out that IL-18BPa has additional anti-inflammatory property through downregulating the expression of IFN-γ and IL-12, at the same time, upregulating the expression of IL-4 and IL-10. Both IFN-γ and IL-12 could upregulated the mRNA and protein levels of IL-18BPa in both the normal and RA subjects. Conclusion: Our results demonstrated the importance of IL-18BPa as an immune regulatory molecule and as a promising therapy for treating RA.
Arthritis & Rheumatism, 2010
ObjectiveTo examine the mechanism of regulation of interleukin‐18 (IL‐18) bioactivity by IL‐18 binding protein (IL‐18BP) induction.MethodsLevels of IL‐18 and IL‐18BPa in synovial fluid samples from patients with osteoarthritis (OA) or rheumatoid arthritis (RA) were determined by enzyme‐linked immunosorbent assays (ELISAs), followed by calculation of free IL‐18. IL‐18 and IL‐18BPa synthesis in RA synovial fibroblasts that had been treated with proinflammatory and antiinflammatory cytokines were assessed by quantitative real‐time polymerase chain reaction and ELISA, respectively, followed by IL‐18 bioactivity determination using KG‐1 cells. Chemical signaling inhibitors were used for determination of the signal transduction pathways involved in IL‐18BPa/IL‐18 regulation. Tumor necrosis factor α (TNFα)–induced caspase 1 activity was determined by a colorimetric assay.ResultsIL‐18BPa was lower in RA synovial fluid than in OA synovial fluid (P < 0.05; n = 8), and free IL‐18 was higher...
Annals of the Rheumatic Diseases, 2002
Objective: To measure interleukin (IL)18 serum concentrations in patients with rheumatoid arthritis (RA) undergoing infliximab treatment (tumour necrosis factor (TNF) α blockade) and to evaluate the concomitant modification of IL12 and IL13 serum concentrations, two cytokines belonging to the Th1 and Th2 profile respectively and biologically related to IL18. Methods: Ten patients with RA not responding to disease modifying antirheumatic drugs (DMARDs) received intravenous infliximab at a dose of 3 mg/kg at baseline and after two and six weeks. Serum samples were collected from all patients before each infusion and assayed for IL18, IL12, and IL13 by enzyme linked immunosorbent assay (ELISA); IL18 was also measured eight weeks after the last infusion. Results: Serum concentrations of IL18 in all patients were already markedly reduced from baseline after two weeks (p<0.005). Serum IL18 was also decreased in a stable manner after six (p<0.01) and 14 weeks (p<0.01) compared with baseline concentrations. No significant modifications were found in serum concentrations of IL12 and IL13 at any time point. Conclusion: There was a rapid and persistent decrease in serum concentrations of IL18 in all the patients studied. This result provides evidence of an in vivo regulation of IL18 by TNFα and suggests that anti-TNFα therapy is likely to interrupt the synergistic effect between these two cytokines.
Annals of The Rheumatic Diseases, 2002
Objective: To measure interleukin (IL)18 serum concentrations in patients with rheumatoid arthritis (RA) undergoing infliximab treatment (tumour necrosis factor (TNF) α blockade) and to evaluate the concomitant modification of IL12 and IL13 serum concentrations, two cytokines belonging to the Th1 and Th2 profile respectively and biologically related to IL18. Methods: Ten patients with RA not responding to disease modifying antirheumatic drugs (DMARDs) received intravenous infliximab at a dose of 3 mg/kg at baseline and after two and six weeks. Serum samples were collected from all patients before each infusion and assayed for IL18, IL12, and IL13 by enzyme linked immunosorbent assay (ELISA); IL18 was also measured eight weeks after the last infusion. Results: Serum concentrations of IL18 in all patients were already markedly reduced from baseline after two weeks (p<0.005). Serum IL18 was also decreased in a stable manner after six (p<0.01) and 14 weeks (p<0.01) compared with baseline concentrations. No significant modifications were found in serum concentrations of IL12 and IL13 at any time point. Conclusion: There was a rapid and persistent decrease in serum concentrations of IL18 in all the patients studied. This result provides evidence of an in vivo regulation of IL18 by TNFα and suggests that anti-TNFα therapy is likely to interrupt the synergistic effect between these two cytokines.
IRF1 is critical for the TNF-driven interferon response in rheumatoid fibroblast-like synoviocytes
Experimental & Molecular Medicine
Rheumatoid arthritis (RA) is an autoimmune disease characterized by persistent synovial inflammation. The major drivers of synovial inflammation are cytokines and chemokines. Among these molecules, TNF activates fibroblast-like synoviocytes (FLSs), which leads to the production of inflammatory mediators. Here, we show that TNF regulates the expression of the transcription factor interferon regulatory factor 1 (IRF1) in human FLSs as well as in a TNF transgenic arthritis mouse model. Transcriptomic analyses of IRF1-deficient, TNF-stimulated FLSs define the interferon (IFN) pathway as a major target of IRF1. IRF1 expression is associated with the expression of IFNβ, which leads to the activation of the JAK-STAT pathway. Blocking the JAK-STAT pathway with the Janus kinase inhibitor (JAKinib) baricitinib or tofacitinib reduces the expression of IFN-regulated genes (IRGs) in TNF-activated FLSs. Therefore, we conclude that TNF induces a distinct inflammatory cascade, in which IRGs are key...
Journal of Biological Chemistry, 2002
Vascular cell adhesion molecule (VCAM)-1 has been implicated in interactions between leukocytes and connective tissue, including rheumatoid arthritis (RA) synovial tissue fibroblasts. Such interactions within the synovium contribute to RA inflammation. Using phosphoinositide 3-kinase (PI3-kinase) inhibitor LY294002 and Src inhibitor PP2, we show that interleukin (IL)-18induced ERK1/2 activation is Src kinase-dependent. Antisense (AS) c-Src oligonucleotide (ODN) treatment reduced IL-18-induced ERK1/2 expression by 32% compared with control, suggesting an upstream role of Src in ERK1/2 activation. AS c-Src ODN treatment also inhibited Akt expression by 74% compared with sense control. PI3-kinase inhibitor LY294002 or AS PI3-kinase ODN inhibited Akt expression. AS c-Src ODN inhibited Akt phosphorylation, confirming Src is upstream of PI3kinase in IL-18-induced RA synovial fibroblast signaling. IL-18 induced a time-dependent activation of c-Src, Ras, and Raf-1, suggesting this signaling cascade plays a role in ERK activation. IL-18 directly activated Src kinase by more than 4-fold over basal levels by enzymatic assay. Electrophoretic mobility shift assay showed that activator protein-1 (AP-1) is activated by IL-18 through ERK and Src but not through PI3-kinase. In an alternate pathway, inhibition of IL-1 receptor-associated kinase-1 (IRAK) with AS ODN to IRAK reduced IL-18-induced expression of nuclear factor B (NFB). Finally, IL-18induced cell surface VCAM-1 expression was inhibited by treatment with AS ODNs to c-Src, IRAK, PI3-kinase, and ERK1/2 by 57, 43, 41, and 32% compared with control sense ODN treatment, respectively. These data support a role for IL-18 activation of three distinct pathways during RA synovial fibroblast stimulation: two Src-dependent pathways and the IRAK/NFB pathway. Targeting VCAM-1 signaling mechanisms may represent therapeutic approaches to inflammatory and angiogenic diseases characterized by adhesion molecule up-regulation.
Arthritis & Rheumatism, 2007
Objective. Interleukin-18 (IL-18) is a proinflammatory cytokine implicated in the pathogenesis of rheumatoid arthritis (RA). This study was undertaken to examine the role of IL-18 in up-regulating secretion of the angiogenic factors stromal cell-derived factor 1␣ (SDF-1␣)/CXCL12, monocyte chemoattractant protein 1 (MCP-1)/CCL2, and vascular endothelial growth factor (VEGF) in RA synovial tissue (ST) fibroblasts, and the underlying signaling mechanisms involved. Methods. We used enzyme-linked immunosorbent assays, Western blotting, and chemical inhibitors/ antisense oligodeoxynucleotides to signaling intermediates to assess the role of IL-18. Results. IL-18 significantly enhanced the production of SDF-1␣/CXCL12, MCP-1/CCL2, and VEGF in RA ST fibroblasts, in a time-and concentrationdependent manner. IL-18-induced SDF-1␣/CXCL12 up-regulation was dependent on JNK, p38 MAPK, phosphatidylinositol 3-kinase (PI3K), and NFB. While IL-18-induced production of SDF-1␣/CXCL12 was also dependent on protein kinase C␦ (PKC␦), production of MCP-1/CCL2 was dependent on PKC␣, not PKC␦. Additionally, RA ST fibroblast IL-18-induced MCP-1/ CCL2 production was mediated by JNK, PI3K, and NFB. In contrast, IL-18 did not induce secretion of RA ST fibroblast MCP-1/CCL2 or VEGF via p38 MAPK. IL-18-induced RA ST fibroblast production of VEGF was mediated mainly by JNK-2, PKC␣, and NFB. IL-18 induced phosphorylation of JNK, PKC␦, p38 MAPK, and activating transcription factor 2 (ATF-2) in RA ST fibroblasts in a time-dependent manner, with JNK-2 being upstream of PKC␦, ATF-2, and NFB. Conclusion. These data support the notion that IL-18 has a unique role in inducing the secretion of angiogenic SDF-1␣/CXCL12, MCP-1/CCL2, and VEGF in RA ST fibroblasts, via distinct signaling intermediates.