Involvement of nuclear factor kB in the regulation of cyclooxygenase‐2 expression by interleukin‐1 in rheumatoid synoviocytes

Abstract

Objective. To evaluate involvement of the transcription factor nuclear factor KB (NF-KB) in the increased expression of cyclooxygenase-2 (COX-2) stimulated by interleukin-lp (IL-1p) in primary rheumatoid synoviocytes.Methods. We treated early-passage rheumatoid synoviocytes with IL-lp and examined the time course of NF-KB translocation to the nucleus by Western blot analysis, as well as NF-KB binding to the COX-2 promoter/enhancer by electrophoretic mobility shift assay. We correlated the time course of NF-KB binding with expression of COX-2 messenger RNA (mRNA) and protein. Synoviocytes were then treated with either sense or antisense phosphorothioate-modified oligonucleotides derived from the transcription start site of the human NF-KB p65 RNA. We analyzed NF-KB binding to the COX-2 promoter and COX-2 protein levels after these treatments.Results. IL-1p rapidly stimulated the translocation of the p65, p50, and c-re1 NF-KB subunits from the cytoplasm to the nucleus. Electrophoretic mobility shift assay demonstrated binding to 2 NF-KB sites within the COX-2 promoter/enhancer, with a time course identical to that of nuclear localization of NF-KB. Supershift analysis revealed that binding activity was due primarily to the p65-p50 heterodimer and the p50 homodimer. Submitted for publication June 7, 1996; accepted in revised form August 21, 1996. mRNA and protein were increased. Pretreatment of RA synoviocytes with NF-KB p65 antisense oligonucleotides resulted in decreased binding to the COX-2 promoter and decreased COX-2 protein expression.Conclusion. These data demonstrate that signaling via the NF-KB pathway is involved in regulation of COX-2 expression induced by IL-1p in RA synoviocytes.

MyD88 signaling in brain endothelial cells is essential for the neuronal activity and glucocorticoid release during systemic inflammation

“…4,5 One candidate gene targeted by NF-kB is the enzyme cyclooxygenase-2 (COX-2) whose activity, along with that of microsomal PGES-1 (mPGES-1), is necessary for the synthesis of PGE 2 during inflammation. [6][7][8][9] However, the promoter of mPGES-1 gene does not contain NF-kB consensus sequences, and instead AP-1 and early growth response-1 appear to be critical for mPGES-1 expression. 10 Although COX-2 and mPGES-1 transcriptional activation takes place in cells of the BBB in various models of systemic inflammation, 4,11 the main cell type expressing these transcripts and producing PGE 2 is still under debate.…”

“…28 Consequently, the exact role of the vascular endothelium and perivascular microglia in the regulation of prostanoid synthesis and activity of the HPA axis has yet to be thoroughly investigated experimentally. 6 Myeloid differentiation factor 88 (MyD88) is a critical component of the signal transduction cascade leading to activation of NF-kB in response to lipopolysaccharide (LPS) or IL-1b. 29 MyD88-deficient mice are resistant to LPS-induced shock and do not display symptoms of anorexia or plasma corticosterone elevation in response to the endotoxin.…”

Cyclooxygenase 2–derived prostaglandin E2 production by corticotropin‐releasing hormone contributes to the activated cAMP response element binding protein content in rheumatoid arthritis synovial tissue

“…In RA synovium, the inducible COX-2 isoform is dramatically up-regulated in response to proinflammatory cytokines. The selective up-regulation of COX-2 is regarded as an important mechanism by which cellular prostaglandin levels are elevated in inflammation (31,33). Therefore, in order to establish the mechanism through which CRH induces PGE 2 production in RA ST, RA ST explant cultures (n ϭ 5) were treated with nonspecific inhibitors of both COX isoforms and specific inhibitors of COX-2, followed by incubation with CRH for 24 hours (Figure 3).…”

“…Among the plethora of genes under IL-1␤ control, cox-2 is particularly sensitive. COX-2 mRNA and protein are induced within 6 hours, and inducible levels are retained for up to 72 hours (33,49). The potentiation of IL-1␤-induced PGE 2 production from RA synovial tissue explants by CRH highlights the ability of CRH to further exacerbate inflammatory responses by conferring significant additive effects on IL-1␤-induced PGE 2 levels.…”

“…The potentiation of IL-1␤-induced PGE 2 production from RA synovial tissue explants by CRH highlights the ability of CRH to further exacerbate inflammatory responses by conferring significant additive effects on IL-1␤-induced PGE 2 levels. IL-1␤ stimulates COX-2 expression in RA synoviocytes via the NF-B pathway, through the translocation and binding of the p65, p50, and c-Rel NF-B subunits to 2 B sites on the cox promoter (33). The p38 MAP kinase cascade is also critical to the magnitude and duration of COX-2 expression (50).…”