title: Hydroxychloroquine potentiates Fas-mediated apoptosis of rheumatoid synoviocytes.
abstract: Inadequate apoptosis may contribute to the synovial hyperplasia associated with rheumatoid arthritis (RA). The Fas-associated death domain protein (FADD)-like interleukin (IL)-1beta-converting enzyme (FLICE)-inhibitory protein (FLIP), which is an apoptotic inhibitor, has been implicated in the resistance to Fas-mediated apoptosis of synoviocytes. This study investigated whether hydroxychloroquine (HCQ), an anti-rheumatic drug, induces the apoptosis of rheumatoid synoviocytes, and modulates the expression of FLIP. Fibroblast-like synoviocytes (FLS) were prepared from the synovial tissues of RA patients, and were cultured with various concentrations of HCQ in the presence or absence of the IgM anti-Fas monoclonal antibodies (mAb) (CH11). Treatment with HCQ, ranging from 1 to 100 microM, induced the apoptosis of FLS in a dose- and time-dependent manner. The increase in synoviocytes apoptosis by HCQ was associated with caspase-3 activation. A combined treatment of HCQ and anti-Fas mAb increased FLS apoptosis and caspase-3 activity synergistically, compared with either anti-Fas mAb or HCQ alone. The Fas expression level in the FLS was not increased by the HCQ treatment, while the FLIP mRNA and protein levels were decreased rapidly by the HCQ treatment. Moreover, time kinetics analysis revealed that the decreased expression of FLIP by HCQ preceded the apoptotic event that was triggered by HCQ plus anti-Fas mAb. Taken together, HCQ increases the apoptosis of rheumatoid synoviocytes by activating caspase-3, and also sensitizes rheumatoid synoviocytes to Fas-mediated apoptosis. Our data suggest that HCQ may exert its anti-rheumatic effect in rheumatoid joints through these mechanisms.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, School of Medicine, Catholic University of Korea, Catholic Research Institutes of Medical Sciences, Seoul, Korea.
authors.forename: W-U
authors.initials: WU
authors.lastname: Kim
authors.forename: S-A
authors.initials: SA
authors.lastname: Yoo
authors.forename: S-Y
authors.initials: SY
authors.lastname: Min
authors.forename: S-H
authors.initials: SH
authors.lastname: Park
authors.forename: H-S
authors.initials: HS
authors.lastname: Koh
authors.forename: S-W
authors.initials: SW
authors.lastname: Song
authors.forename: C-S
authors.initials: CS
authors.lastname: Cho
mesh_terms: D018501:Antirheumatic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001172:Arthritis, Rheumatoid / Q000378:metabolism / Q000473:pathology*; D015153:Blotting, Western / Q000379:methods; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004357:Drug Synergism; D006801:Humans; D006886:Hydroxychloroquine / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013583:Synovial Membrane / Q000378:metabolism / Q000473:pathology*; D019014:fas Receptor / Q000378:metabolism / Q000502:physiology*
chemical_list: D018501:Antirheumatic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D061945:Caspase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D019014:fas Receptor; D006886:Hydroxychloroquine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases