title: Toll-like receptor 9-dependent activation of bone marrow-derived dendritic cells by URA5 DNA from Cryptococcus neoformans.
abstract: Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningoencephalitis in immunocompromised patients. Recently, we reported that Toll-like receptor 9 (TLR9) is involved in host defense against C. neoformans: specifically, it detects the pathogen's DNA. In the present study, we aimed to elucidate the mechanisms underlying TLR9-mediated activation of innate immune responses by using the URA5 gene, which encodes a virulent component of this fungal pathogen. A PCR-amplified 345-bp URA5 gene fragment induced interleukin-12 p40 (IL-12p40) production by bone marrow-derived dendritic cells (BM-DCs) in a TLR9-dependent manner. Similar activity was detected in the 5' 129-bp DNA fragment of URA5 and in a synthesized oligodeoxynucleotide (ODN) with the same sequence. Shorter ODN fragments, which contained GTCGGT or GACGAT but had only 24 or 21 bases, induced IL-12p40 production and CD40 expression by BM-DCs, but this activity vanished when the CG sequence was replaced by GC or when a phosphorothioate modification was introduced. IL-12p40 production caused by active ODN was strikingly enhanced by treatment with DOTAP, a cationic lipid that increases the uptake of DNA by BM-DCs, though DOTAP failed to induce IL-12p40 production by inactive ODN and did not affect the activity of an ODN-containing canonical CpG motif. There was no apparent difference in intracellular trafficking between active and inactive ODNs. Finally, an extremely high dose of inactive ODN suppressed IL-12p40 production by BM-DCs that had been stimulated with active ODN. These results suggest that the C. neoformans URA5 gene activates BM-DCs through a TLR9-mediated signaling pathway, using a mechanism possibly independent of the canonical CpG motif.
authors: Department of Medical Microbiology, Mycology and Immunology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors: Misuzu
authors: M
authors: Tanaka
authors: Keiko
authors: K
authors: Ishii
authors: Yuri
authors: Y
authors: Nakamura
authors: Akiko
authors: A
authors: Miyazato
authors: Atsuko
authors: A
authors: Maki
authors: Yuzuru
authors: Y
authors: Abe
authors: Tomomitsu
authors: T
authors: Miyasaka
authors: Hideki
authors: H
authors: Yamamoto
authors: Yukiko
authors: Y
authors: Akahori
authors: Misaki
authors: M
authors: Fue
authors: Yurie
authors: Y
authors: Takahashi
authors: Emi
authors: E
authors: Kanno
authors: Ryoko
authors: R
authors: Maruyama
authors: Kazuyoshi
authors: K
authors: Kawakami
mesh_terms: D000818:Animals; D003455:Cryptococcus neoformans / Q000235:genetics* / Q000378:metabolism*; D004271:DNA, Fungal / Q000276:immunology; D003713:Dendritic Cells / Q000502:physiology*; D005229:Fatty Acids, Monounsaturated; D015966:Gene Expression Regulation, Fungal; D053762:Interleukin-12 Subunit p40 / Q000378:metabolism; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009962:Orotate Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D005229:Fatty Acids, Monounsaturated; D053762:Interleukin-12 Subunit p40; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D051217:Toll-Like Receptor 9; C083120:phosphorodithioic acid; D009962:Orotate Phosphoribosyltransferase; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane