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Induction of Inducible Nitric Oxide Synthase, Argininosuccinate Synthase, and GTP Cyclohydrolase I in Arthritic Joints of Human Tumor Necrosis Factor-a Transgenic Mice
MIKA HUKKANEN, LOUISE A.M. PLATTS, SYLVA HARALAMBOUS, MARI AINOLA, YRJÖ T. KONTTINEN, GEORGE KOLLIAS, and JULIA M. POLAK
ABSTRACT.
Methods. We used 4 and 8-week-old Tg197 h-TNF-a transgenic mice and wild-type CBA ´ C57B1/6 control mice to investigate the expression of iNOS with respect to that of AS, GTPCH, and 3-nitrotyrosine by quantitative RT-PCR and immunocytochemistry. Urinary NO metabolites were analyzed using a chemiluminescence assay. Results. Inducible NOS, AS, and GTPCH mRNA was found in all study groups; however, only iNOS mRNA showed a clear increase in 4-week-old Tg197 h-TNF-a transgenics in comparison to age matched wild-type controls. Abundant iNOS protein expression was found in macrophages and vascular smooth muscle cells in hyperplastic synovium and pannus. AS expression was found in vascular endothelium and fibroblasts of the inflammatory synovium and pannus. GTPCH immunoreactivity was mostly restricted to macrophages in inflammatory synovium. Localization of 3-nitrotyrosine overlapped with that of iNOS, indicating formation of reactive nitrogen species. Consistent with the high output NO generation, there was a 5-fold increase in urinary NO metabolites in 8-week-old Tg197 h-TNF-a transgenic mice. Conclusion. We characterized the Tg197 h-TNF-a transgenic model of inflammatory arthritis in terms of high output NO-generating pathway, and showed that both AS and GTPCH are intimately associated with inflammatory arthritis. The concomitant induction of AS and GTPCH with that of iNOS suggests that they may be important modulators of arthritis, and that they may represent novel targets for modulation of disease activity. (J Rheumatol 2003;30:652-9) Key Indexing Terms:
ARGININOSUCCINATE SYNTHASE
From the Institute of Biomedicine/Anatomy, Biomedicum Helsinki, University of Helsinki; ORTON Research Institute, the Orthopaedic Hospital of the Invalid Foundation, Helsinki; Department of Medicine/Invärtes Medicin, Helsinki University Central Hospital, Helsinki, Finland; Tissue Engineering Centre, Imperial College School of Medicine, Chelsea and Westminster Hospital, London, UK; Laboratory of Molecular Genetics, Hellenic Pasteur Institute, Athens, Greece; and Institute of Immunology, Biomedical Sciences Center "Alexander Fleming," Varkiza, Greece. Supported by grants from the Academy of Finland, the University of Helsinki, clinical EVO research grants (from the Invalid Foundation and TYH 0056; TYH 0215; TYH 0341; TYH 8307), and the Group of Excellence scheme by the Academy of Finland, the National Technology Agency, Ministry of Education, and University of Helsinki, Finland. M. Hukkanen, PhD, Associate Professor and Academy Fellow, Institute of Biomedicine/Anatomy, Biomedicum Helsinki, University of Helsinki, and ORTON Research Institute, Orthopaedic Hospital of the Invalid Foundation; L.A.M. Platts, PhD, Research Scientist; J.M. Polak, MD, DSc, FRCP, FRCPath, Professor, Tissue Engineering Centre, Imperial College School of Medicine, Chelsea and Westminster Hospital; S. Haralambous, PhD, Senior Scientist, Laboratory of Molecular Genetics, Hellenic Pasteur Institute; M. Ainola, MSc, Research Scientist, Institute of Biomedicine/Anatomy, Biomedicum Helsinki, University of Helsinki; Y.T. Konttinen, MD, PhD, Professor, Department of Medicine/Invärtes Medicin, Helsinki University Central Hospital, Helsinki, and ORTON Research Institute, Orthopaedic Hospital of the Invalid Foundation; G. Kollias, PhD, Professor, Laboratory of Molecular Genetics, Hellenic Pasteur Institute, Institute of Immunology, Biomedical Sciences Center "Alexander Fleming." Address reprint requests to Dr. M. Hukkanen, Biomedicum Helsinki, Institute of Biomedicine/Anatomy, PO Box 63 (Haartmaninkatu 8), FIN-00014 University of Helsinki, Helsinki, Finland. E-mail: mika.hukkanen@helsinki.fi Submitted February 28, 2002; revision accepted September 10, 2002. |