Toll-like receptor 9-dependent activation of bone marrow-derived dendritic cells by URA5 DNA from Cryptococcus neoformans

Misuzu Tanaka, Keiko Ishii, Yuri Nakamura, Akiko Miyazato, Atsuko Maki, Yuzuru Abe, Tomomitsu Miyasaka, Hideki Yamamoto, Yukiko Akahori, Misaki Fue, Yurie Takahashi, Emi Kanno, Ryoko Maruyama, Kazuyoshi Kawakami

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13 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)778-786
Number of pages9
JournalInfection and immunity
Volume80
Issue number2
DOIs
Publication statusPublished - 2012 Feb

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases

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    Tanaka, M., Ishii, K., Nakamura, Y., Miyazato, A., Maki, A., Abe, Y., Miyasaka, T., Yamamoto, H., Akahori, Y., Fue, M., Takahashi, Y., Kanno, E., Maruyama, R., & Kawakami, K. (2012). Toll-like receptor 9-dependent activation of bone marrow-derived dendritic cells by URA5 DNA from Cryptococcus neoformans. Infection and immunity, 80(2), 778-786. https://doi.org/10.1128/IAI.05570-11