title: Interleukin-18 induces the production of vascular endothelial growth factor (VEGF) in rheumatoid arthritis synovial fibroblasts via AP-1-dependent pathways.
abstract: Interleukin-18 (IL-18) is a novel pro-inflammatory cytokine which has been implicated to play a pathogenic role in rheumatoid arthritis (RA). Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis in rheumatoid synoviocytes. In present study, we examined the effect of IL-18 on VEGF production in fibroblast-like synoviocytes (FLS) isolated from the patients with RA. FLS were prepared from the synovial tissues of patients with RA and osteoarthritis (OA) and cultured in the presence of IL-18. The production of VEGF from FLS was measured in culture supernatants by enzyme-linked immunosorbent assay (ELISA). The VEGF messenger RNA (mRNA) expression and AP-1 binding activity of VEGF transcript were determined by reverse transcription-polymerase chain reaction (RT-PCR) and electrophoretic mobility shift assay (EMSA). IL-18 and VEGF levels of sera and synovial fluids (SF) of RA patients (n=30) were significantly higher than those of OA patients (n=20). IL-18 dose-dependently increased the production of VEGF. The effect of IL-18 on VEGF production appeared to be as potent as IL-1beta, whereas tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma showed little effects on VEGF production. AP-1-specific inhibitor Curcumin dose-dependently abrogated the effect of IL-18 on VEGF production. The VEGF enhancement of IL-18 was associated with increased AP-1 binding activity to the VEGF promoter site. These findings suggest IL-18 as an angiogenic factor in RA and down-regulation of IL-18 activity or AP-1 signal pathway can be potential therapeutic targets for RA.
authors.affiliation: Department of Medicine, The Center for Rheumatic Diseases, The Rheumatism Research Center (RhRC), Catholic Research Institutes of Medical Sciences, Catholic University of Korea, Seoul 137-701, Republic of Korea. iammila@catholic.ac.kr
authors.forename: Mi-La
authors.initials: ML
authors.lastname: Cho
authors.forename: Young Ok
authors.initials: YO
authors.lastname: Jung
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Moon
authors.forename: So-Youn
authors.initials: SY
authors.lastname: Min
authors.forename: Chong-Hyeon
authors.initials: CH
authors.lastname: Yoon
authors.forename: Sang-Heon
authors.initials: SH
authors.lastname: Lee
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Park
authors.forename: Chul-Soo
authors.initials: CS
authors.lastname: Cho
authors.forename: Dae-Myung
authors.initials: DM
authors.lastname: Jue
authors.forename: Ho-Youn
authors.initials: HY
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000378:metabolism*; D002478:Cells, Cultured; D003474:Curcumin / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005347:Fibroblasts / Q000502:physiology*; D006801:Humans; D020382:Interleukin-18 / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D013582:Synovial Fluid / Q000378:metabolism; D013583:Synovial Membrane / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D020382:Interleukin-18; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D042461:Vascular Endothelial Growth Factor A; D004247:DNA; D003474:Curcumin