title: FK506 augments glucocorticoid-mediated cyclooxygenase-2 down-regulation in human rheumatoid synovial fibroblasts.
abstract: Prostaglandins (PG) formed by cyclooxygenase (COX) enzymes are important mediators of inflammation in rheumatoid arthritis. The contribution of the inducible COX-2 to inflammation in the rheumatoid synovium is well documented. We examined the regulation of COX-2 mRNA and protein expression in response to both glucocorticoids (GC) and FK506 using rheumatoid synovial fibroblasts. Combined treatment of FK506 and a low concentration of dexamethasone (DEX) (10(-9) M) down-regulated synovial COX-2 mRNA and protein expression. In contrast, neither FK506 nor DEX (10(-9) M) alone influenced COX-2 expression. Immunocytochemical studies showed that pretreatment with FK506 enhanced the nuclear translocation of the glucocorticoid receptor (GR) in synovial fibroblasts in the presence of low concentrations of DEX (10(-9) M). Transient transfection experiments showed that treatment of cells with FK506 enhanced the expression of glucocorticoid-responsive gene reporter in the presence of DEX (10(-9) M). NF-kappaB is known to mediate the transcriptional activation of the COX-2 gene. Electrophoretic mobility shift assay demonstrated that DNA-binding activity of NF-KB was suppressed more profoundly by FK506 plus DEX (10(-9) M) treatment with those of DEX (10(-9)M) alone in IL-1beta-stimulated synovial cells. Our results indicated that FK506-induced potentiation of GR-mediated repression of synovial COX-2 gene transcription is the result of increased translocation of GR to the nucleus and subsequent repression of NF-kappaB transactivation. Our results also suggest that FK506 may exert anti-inflammatory effects in the rheumatoid synovium by potentiating GR-mediated signal transduction.
authors.affiliation: The First Department of Internal Medicine, Nagasaki University School of Medicine, Japan. eguchi@net.nagasaki-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Migita
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Okamoto
authors.forename: N
authors.initials: N
authors.lastname: Yoshikawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ichinose
authors.forename: S
authors.initials: S
authors.lastname: Urayama
authors.forename: S
authors.initials: S
authors.lastname: Yamasaki
authors.forename: H
authors.initials: H
authors.lastname: Ida
authors.forename: Y
authors.initials: Y
authors.lastname: Kawabe
authors.forename: A
authors.initials: A
authors.lastname: Kawakami
authors.forename: K
authors.initials: K
authors.lastname: Eguchi
mesh_terms: D001172:Arthritis, Rheumatoid / Q000201:enzymology* / Q000473:pathology; D001483:Base Sequence; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D017931:DNA Primers; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism; D013583:Synovial Membrane / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D016559:Tacrolimus / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D017931:DNA Primers; D007527:Isoenzymes; D008565:Membrane Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D016559:Tacrolimus