title: Cell-specific inhibition of inducible nitric oxide synthase activation by leflunomide.
abstract: The influence of a novel immunomodulating drug, leflunomide, on iNOS-dependent nitric oxide (NO) production in rodent macrophages and fibroblasts was investigated. Leflunomide's active metabolite A77 1726 caused a dose-dependent decrease of NO production in IFN-gamma-treated L929 fibroblasts. The observed effect was cell-specific, as well as stimulus-specific, since A77 1726 did not affect NO production in IFN-gamma-stimulated murine peritoneal macrophages or db-cAMP-treated L929 cells. A77 1726 reduced expression of IFN-gamma-induced iNOS and IRF-1 mRNA in L929 cells, while iNOS enzymatic activity remained unchanged. Specific inhibitor of MAP kinase kinase (MEK), PD98059, but not unselective protein kinase inhibitor genistein, completely mimicked cell-type-specific and stimulus-specific NO-inhibitory action of leflunomide. Therefore, the recently described inhibition of MEK/MAP pathway by leflunomide could present a possible mechanism for its suppression of iNOS activation in L929 fibroblasts. Finally, a similar inhibitory effect of A77 1726 on both NO production and iNOS mRNA expression was observed also in IFN-gamma + LPS-activated murine and rat primary fibroblasts.
authors.affiliation: Institute of Microbiology and Immunology, University of Belgrade, Belgrade, Yugoslavia.
authors.forename: V
authors.initials: V
authors.lastname: Jankovic
authors.forename: T
authors.initials: T
authors.lastname: Samardzic
authors.forename: S
authors.initials: S
authors.lastname: Stosic-Grujicic
authors.forename: D
authors.initials: D
authors.lastname: Popadic
authors.forename: V
authors.initials: V
authors.lastname: Trajkovic
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000814:Aniline Compounds / Q000494:pharmacology; D000818:Animals; D002384:Catalysis / Q000187:drug effects; D002478:Cells, Cultured; D003437:Crotonates; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D006885:Hydroxybutyrates / Q000494:pharmacology; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000494:pharmacology; D007555:Isoxazoles / Q000494:pharmacology*; D000077339:Leflunomide; D051379:Mice; D008808:Mice, Inbred CBA; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009570:Nitriles; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D051381:Rats; D014052:Toluidines; D014407:Tumor Cells, Cultured
chemical_list: D000276:Adjuvants, Immunologic; D000814:Aniline Compounds; D003437:Crotonates; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D006885:Hydroxybutyrates; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; C494259:Irf1 protein, rat; D007555:Isoxazoles; D009570:Nitriles; D010750:Phosphoproteins; D012333:RNA, Messenger; D014052:Toluidines; C527525:teriflunomide; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat; D020928:Mitogen-Activated Protein Kinases; D000077339:Leflunomide; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one