Preactivation exposure of RAW 264.7 cells to taurine chloramine attenuates subsequent production of nitric oxide and expression of iNOS mRNA

• Published in: Journal of leukocyte biology Vol. 61; no. 2; pp. 161 - 166
• Main Authors: Park, E, Schuller-Levis, G, Jia, J H, Quinn, M R
• Format: Journal Article
• Language: English
• Published: United States Society for Leukocyte Biology 01.02.1997
• Subjects: Animals; Cell Line; Cell Survival - drug effects; Dose-Response Relationship, Drug; inflammation; Inflammation Mediators - pharmacology; macrophage activation; Macrophage Activation - drug effects; Macrophages - drug effects; Macrophages - immunology; Macrophages - metabolism; Mice; Nitric Oxide - antagonists & inhibitors; Nitric Oxide - biosynthesis; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - biosynthesis; Nitric Oxide Synthase - genetics; RNA, Messenger - biosynthesis; taurine; Taurine - analogs & derivatives; Taurine - pharmacology
• ISSN: 0741-5400; 1938-3673
• DOI: 10.1002/jlb.61.2.161

Recent studies demonstrate that taurine chloramine (Thu‐Cl) inhibits production of nitric oxide (NO) and other proinflammatory mediators in cultured macrophages when added to the media at the time of activation. Because Thu‐Cl may react with various media constituents and it is difficult to measure Thu‐Cl in complex solutions, we designed experiments to more carefully control cell exposure to various chloramines and NaOCl. RAW 264.7 cells were exposed to 1 mM of NaOCl, Thu‐Cl, or chloramine preparations of the following amino acids: l‐alanine (l‐Ala‐Cl), β‐alanine (β‐Ala‐Cl), serine (Ser‐Cl), or glycine (Gly‐Cl) in Hanks' balanced salt solution (HBSS) for up to 2 h (37°C, 5%CO2). The HBSS solution was then replaced with complete media containing interferon‐γ (IFN‐γ) and lipopolysaccharide (LPS) for an additional 24 h before measuring cell viability. The chemical stability of NaOCl and each chloramine was evaluated after various times of preactivation exposure by measuring retention of each solution's UV absorption spectra and ability to oxidize KI. Cytotoxicity of each solution was evaluated by the maintained ability of RAW 264.7 cells to reduce MIT. Whereas Thu‐Cl, β‐Ala‐Cl, and Gly‐Cl were stable chloramines, only Thu‐Cl was not cytotoxic. l‐Ala‐Cl, Ser‐Cl, and the highly reactive oxidant NaOCl were unstable and toxic. In further studies RAW 264.7 cells were exposed to Thu‐Cl in HBSS for 2 h and the solution was then replaced with complete media containing IFN‐γ and LPS, taxol, lipoarabinomannan, or interleukin‐2. Production of NO was measured 24 h later and was inhibited in activated cells that were previously exposed to Thu‐Cl. Inhibition of NO production was dependent on Thu‐Cl concentration and was accounted for by reduced expression of inducible nitric oxide synthase mRNA, regardless of activator combinations. These results support the idea that Thu‐Cl has the potential to function as an inhibitory modulator of inflammation. J. Leukoc. Biol. 61: 161–166; 1997.