title: Myo-inositol restores the inflammation-induced down-regulation of taurine transport by the murine macrophage cell line, RAW 264.7.
abstract: The role of myo-inositol in the regulation of taurine transport in activated murine macrophage cell line, RAW 264.7, was studied. Challenge of RAW 264.7 murine macrophages for 24 hr with phorbol ester 12-myristate 13-acetate (PMA) (10 ng/ml), a PKC activator, resulted in a 62% decrease in taurine transport activity. Among the various monosaccharides (1 mM) tested in the presence of PMA, myo-inositol was most effective in restoring the PMA-induced down-regulation of taurine transport in murine macrophages (82% increase compared to the value for cells treated with PMA Alone, p < 0.01). The protective role of myo-inositol against stress-induced down-regulation of taurine transport by macrophages was further investigated in conditions mimicking bacterial infection, inflammation, and immune-suppressed circumstances. A challenge of murine macrophages with lipopolysaccharide (LPS) (0.1 and 10 microg/ml) resulted in a 60% decrease in taurine transport activity compared to the value for untreated control cells (p < 0.01). When cells were co-treated with myo-inositol (100 nM approximately 10 mM) in the presence of LPS for 24 hrs, taurine transport activity increased in a dose-dependent manner compared to the value for cells treated with LPS only. Taurine transport activity in cells treated with LPS (10 microg/ml) plus interferon-gamma (IFN-gamma) (150 unit/ml) for 24 hrs was 13% of the value for untreated control cells (p < 0.01). Again, this inflammation-induced down-regulation of taurine transport activity was completely antagonized with co-administration of 100 nM or higher levels of myo-inositol in the culture medium. Similarly, myo-inositol effectively restored the taurine transport activity suppressed by cyclosporin A (0.5 and 50 nM) in murine macrophages (p < 0.01). From these results, myo-inositol appears to be a common accelerator of taurine transport by murine macrophages in diverse conditions of down-regulated taurine transport.
authors.affiliation: Department of Life Science, University of Seoul, Seoul 130-743, South Korea.
authors.forename: Ha Won
authors.initials: HW
authors.lastname: Kim
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Hye Suk
authors.initials: HS
authors.lastname: An
authors.forename: Kun Koo
authors.initials: KK
authors.lastname: Park
authors.forename: Byong Kak
authors.initials: BK
authors.lastname: Kim
authors.forename: Taesun
authors.initials: T
authors.lastname: Park
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D015536:Down-Regulation; D007294:Inositol / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009005:Monosaccharides / Q000378:metabolism; D013654:Taurine / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity
chemical_list: D009005:Monosaccharides; D013654:Taurine; D007294:Inositol; D013755:Tetradecanoylphorbol Acetate