title: IFN-gamma primes macrophage responses to bacterial DNA.
abstract: Macrophages recognize and are activated by unmethylated CpG motifs in bacterial DNA. Here we demonstrate that production of nitric oxide (NO) from murine RAW 264 macrophages and bone marrow-derived macrophages (BMM) in response to bacterial DNA is absolutely dependent on interferon-gamma (IFN-gamma) priming. Similarly, arginine uptake and expression of the inducible nitric oxide synthase (iNOS) gene in response to bacterial DNA in BMM occurred only after IFN-gamma priming. In contrast, mRNA for the cationic amino acid transporter, CAT2, was induced by plasmid DNA alone, and priming with IFN-gamma had no effect on this response. Tumor necrosis factor-alpha (TNF-alpha) release from RAW 264 and BMM in response to bacterial DNA was augmented by IFN-gamma pretreatment. In a stably transfected HIV-1 long terminal repeat (LTR) luciferase RAW 264 cell line, IFN-gamma and bacterial DNA synergized in activation of the HIV-1 LTR. Bacterial DNA has been shown to induce IFN-gamma production in vivo as an indirect consequence of interleukin-12 (IL-12) and TNF-alpha production from macrophages. The results herein suggest the existence of a self-amplifying loop that may have implications for therapeutic applications of bacterial DNA.
authors.affiliation: Centre for Molecular and Cellular Biology, Department of Microbiology, University of Queensland, Brisbane, Australia.
authors.forename: M J
authors.initials: MJ
authors.lastname: Sweet
authors.forename: K J
authors.initials: KJ
authors.lastname: Stacey
authors.forename: D K
authors.initials: DK
authors.lastname: Kakuda
authors.forename: D
authors.initials: D
authors.lastname: Markovich
authors.forename: D A
authors.initials: DA
authors.lastname: Hume
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D002374:Catalase / Q000235:genetics; D002460:Cell Line; D004269:DNA, Bacterial / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics; D007371:Interferon-gamma / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008815:Mice, Inbred Strains; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D012333:RNA, Messenger; D009569:Nitric Oxide; D007371:Interferon-gamma; D001120:Arginine; D002374:Catalase; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse