title: 5-Lipoxygenase inhibitors attenuate TNF-α-induced inflammation in human synovial fibroblasts.
abstract: The lipoxygenase isoform of 5-lipoxygenase (5-LOX) is reported to be overexpressed in human rheumatoid arthritis synovial tissue and involved in the progress of inflammatory arthritis. However, the detailed mechanism of how 5-lipoxygenase regulates the inflammatory response in arthritis synovial tissue is still unclear. The aim of this study was to investigate the involvement of lipoxygenase pathways in TNF-α-induced production of cytokines and chemokines. Human synovial fibroblasts from rheumatoid patients were used in this study. 5-LOX inhibitors and shRNA were used to examine the involvement of 5-LOX in TNF-α-induced cytokines and chemokines expression. The signaling pathways were examined by Western Blotting or immunofluorescence staining. The effect of 5-LOX inhibitor on TNF-α-induced chemokine expression and paw edema was also explored in vivo in C57BL/6 mice. Treatment with 5-LOX inhibitors significantly decreased TNF-α-induced pro-inflammatory mediators including interleukin-6 (IL-6) and monocyte chemo-attractant protein-1 (MCP-1) in human synovial fibroblasts. Knockdown of 5-LOX using shRNA exerted similar inhibitory effects. The abrogation of NF-κB activation was involved in the antagonizing effects of these inhibitors. Furthermore, 5-LOX inhibitor decreased TNF-α-induced up-regulation of serum MCP-1 level and paw edema in mouse model. Our results provide the evidence that the administration of 5-LOX inhibitors is able to ameliorate TNF-α-induced cytokine/chemokine release and paw edema, indicating that 5-LOX inhibitors may be developed for therapeutic treatment of inflammatory arthritis.
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Han-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Tzu-Hung
authors.initials: TH
authors.lastname: Lin
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Ming-Yueh
authors.initials: MY
authors.lastname: Wu
authors.affiliation: Department of Orthopaedics, Taichung Veterans General Hospital, Taichung, Taiwan.
authors.forename: Yung-Cheng
authors.initials: YC
authors.lastname: Chiu
authors.affiliation: Department of Pharmacology, College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Tang
authors.affiliation: School of Pharmacy, College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Mann-Jen
authors.initials: MJ
authors.lastname: Hour
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Houng-Chi
authors.initials: HC
authors.lastname: Liou
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Huang-Ju
authors.initials: HJ
authors.lastname: Tu
authors.affiliation: Department of Orthopedics, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Rong-Sen
authors.initials: RS
authors.lastname: Yang
authors.affiliation: Department of Pharmacology, College of Medicine, National Taiwan University and Hospital, Taipei, Taiwan.
authors.forename: Wen-Mei
authors.initials: WM
authors.lastname: Fu
mesh_terms: D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D018932:Chemokine CCL2 / Q000097:blood / Q000235:genetics / Q000378:metabolism; D004487:Edema / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D055786:Gene Knockout Techniques; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D013583:Synovial Membrane / Q000473:pathology*; D014409:Tumor Necrosis Factor-alpha / Q000009:adverse effects*
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D015850:Interleukin-6; D016859:Lipoxygenase Inhibitors; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D007975:Leukotriene B4; D001094:Arachidonate 5-Lipoxygenase; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human