Nitric oxide production: a mechanism of Chlamydia trachomatis inhibition in interferon-gamma-treated RAW264.7 cells.
IFN-gamma and/or LPS induced nitrite production and inhibition of Chlamydia trachomatis (CT) replication in the murine macrophage cell line, RAW264.7. Linear regression analysis demonstrated a strong correlation between nitrite production and inhibition of CT replication (correlation coefficients: -0.93, P < 0.001). L-NMMA specifically inhibited nitrite production and restored CT replication (55-71%). Inducible nitric oxide synthase (iNOS) mRNA was analyzed by Northern and dot blot hybridization with an iNOS cDNA probe. A strong correlation between iNOS mRNA expression and inhibition of CT replication also was observed (correlation coefficient: -0.97, P < 0.05). Furthermore, anti-TNF-alpha antibody, which completely neutralized biological activity of the secreted TNF-alpha, neither inhibited nitrite production nor restored CT replication in the LPS- and/or IFN-gamma-treated RAW264.7 cells. In mouse peritoneal macrophages treated with IFN-gamma, both L-NMMA and anti-TNF-alpha antibody inhibited nitrite production and restored CT replication. However, L-NMMA and the antibody had no effect upon nitrite production and CT inhibition in LPS-treated peritoneal macrophages. These data indicate that NO production is one mechanism for inhibition of CT replication in IFN-gamma-activated murine macrophages.
Chen
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B
Department of Microbiology, James Quillen College of Medicine, East Tennessee State University, Johnson City 37614, USA.
Stout
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R
Campbell
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WF
D000818:Animals; D002460:Cell Line; D002692:Chlamydia trachomatis / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D007371:Interferon-gamma / Q000494:pharmacology*; D016014:Linear Models; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology*; D017737:Macrophages, Peritoneal / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D014364:Tryptophan / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D008070:Lipopolysaccharides; D009573:Nitrites; D012329:RNA, Bacterial; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D007371:Interferon-gamma; D014364:Tryptophan; D019001:Nitric Oxide Synthase