title: Effects of 5-lipoxygenase inhibitors on interleukin production by human synovial tissues in organ culture: comparison with interleukin-1-synthesis inhibitors.
abstract: Prostaglandins and leukotrienes differentially regulate the production of interleukin-1 (IL-1) in monocytes. It was, therefore, decided to investigate the effects of some 5-lipoxygenase inhibitors compared with standard IL-1 synthesis inhibitors on the production of IL-1 by human synovial tissue explants in organ culture. Human synovial (from hip/knee arthroplasty) or porcine tibio-tarsal joint synovial explants were incubated in organ culture in Dulbecco's Modified Eagle's Medium + 5% foetal calf serum in the presence of the test compounds or solvents (controls), or media alone for 1-5 days. Total bioactive IL-1 was assayed in the medium (following serial dilution or with polyethylene glycol 8000 added in some assays to remove inhibitors) using the D-10 T-cell bioassay. Some assays of interleukins 1 alpha, 1 beta, 6 or 8 were performed by ELISA. Of the 5-lipoxygenase inhibitors investigated, MK-886(3-(1-(4-chlorobenzyl)-3-tert-butyl-thio-5-isopropylindol-2- yl)-2,2 -dimethyl propanoic acid), L-656,224 ((7-chloro-2-[4-methoxypenyl]methyl)-3 -methyl-5-propyl-4-benzofuranol), PF-5901 and tepoxalin were the most potent inhibitors of IL-1 production. While the PF-5901 was effective at 5-30 microM and tepoxalin was effective at 1-10 microM, the others were the most potent having minimal inhibitory activity in the range of 0.01-0.1 microM. The presumed IL-1-synthesis inhibitors, tenidap and IX-207,887, were inactive at concentrations of 30-50 microM. Leukotriene B4 (1-100 ng/mL-1) added to MK-886 (5 microM)-treated cultures reversed the inhibitory effects of the latter on IL-1, confirming the role of 5-lipoxygenase products in the regulation of IL-1 production. Addition of polyethylene glycol 8000 to MI-886-treated cultures eliminated the inhibitory effects of this drug, suggesting that this drug exerts its effects by promoting production of IL-1 inhibitors. MK-886 also inhibited synovial production of two other pleiotrophic cytokines which it regulates, IL-6 and IL-8. The results suggest that some 5-lipoxygenase inhibitors may be usefully employed in regulating production of those interleukins involved in joint cartilage destruction.
authors.affiliation: Division of Biomedical Sciences, Sheffield Hallam University, UK.
authors.forename: K D
authors.initials: KD
authors.lastname: Rainsford
authors.forename: C
authors.initials: C
authors.lastname: Ying
authors.forename: F
authors.initials: F
authors.lastname: Smith
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006621:Hip Joint; D006801:Humans; D006918:Hydroxyurea / Q000031:analogs & derivatives / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D007719:Knee Joint; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology; D009924:Organ Culture Techniques; D000078183:Oxindoles; D011720:Pyrazoles / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013552:Swine; D013583:Synovial Membrane / Q000187:drug effects* / Q000378:metabolism; D013643:Tarsus, Animal; D013844:Thiazoles / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D002722:Chlorobenzenes
chemical_list: D001572:Benzofurans; D006918:Hydroxyurea; D007211:Indoles; D007375:Interleukin-1; D016859:Lipoxygenase Inhibitors; D009281:Naphthalenes; D000078183:Oxindoles; D011720:Pyrazoles; D011804:Quinolines; D013844:Thiazoles; D013876:Thiophenes; C060893:MK-886; D002722:Chlorobenzenes; C049740:alpha-pentyl-3-(2-quinolinylmethoxy)benzenemethanol; C055868:L 656224; C061029:IX 207-887; C069794:ICI 211965; C062866:tenidap; C073135:tepoxalin; C063449:zileuton