title: Deoxynucleic acids from Cryptococcus neoformans activate myeloid dendritic cells via a TLR9-dependent pathway.
abstract: The mechanism of host cell recognition of Cryptococcus neoformans, an opportunistic fungal pathogen in immunocompromised patients, remains poorly understood. In the present study, we asked whether the DNA of this yeast activates mouse bone marrow-derived myeloid dendritic cells (BM-DCs). BM-DCs released IL-12p40 and expressed CD40 upon stimulation with cryptococcal DNA, and the response was abolished by treatment with DNase, but not with RNase. IL-12p40 production and CD40 expression were attenuated by chloroquine, bafilomycin A, and inhibitory oligodeoxynucleotides (ODN) that suppressed the responses caused by CpG-ODN. Activation of BM-DCs by cryptococcal DNA was almost completely abrogated in TLR9 gene-disrupted (TLR9(-/-)) mice and MyD88(-/-) mice, similar to that by CpG-ODN. In addition, upon stimulation with whole yeast cells of acapsular C. neoformans, TLR9(-/-) BM-DCs produced a lower amount of IL-12p40 than those from wild-type mice, and TLR9(-/-) mice were more susceptible to pulmonary infection with this fungal pathogen than wild-type mice, as shown by increased number of live colonies in lungs. Treatment of cryptococcal DNA with methylase resulted in reduced IL-12p40 synthesis by BM-DCs. Furthermore, using a luciferase reporter assay, cryptococcal DNA activated NF-kappaB in HEK293 cells transfected with the TLR9 gene. Finally, confocal microscopy showed colocalization of fluorescence-labeled cryptococcal DNA with CpG-ODN and the findings merged in part with the distribution of TLR9 in BM-DCs. Our results demonstrate that cryptococcal DNA causes activation of BM-DCs in a TLR9-dependent manner and suggest that the CpG motif-containing DNA may contribute to the development of inflammatory responses after infection with C. neoformans.
authors.affiliation: Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Nakamura
authors.forename: Akiko
authors.initials: A
authors.lastname: Miyazato
authors.forename: Gang
authors.initials: G
authors.lastname: Xiao
authors.forename: Masumitsu
authors.initials: M
authors.lastname: Hatta
authors.forename: Ken
authors.initials: K
authors.lastname: Inden
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Aoyagi
authors.forename: Kohei
authors.initials: K
authors.lastname: Shiratori
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takeda
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Shinobu
authors.initials: S
authors.lastname: Saijo
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Iwakura
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Adachi
authors.forename: Naohito
authors.initials: N
authors.lastname: Ohno
authors.forename: Kazuo
authors.initials: K
authors.lastname: Suzuki
authors.forename: Jiro
authors.initials: J
authors.lastname: Fujita
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kaku
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Kawakami
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D003455:Cryptococcus neoformans / Q000737:chemistry* / Q000276:immunology*; D004271:DNA, Fungal / Q000378:metabolism / Q000502:physiology*; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D053762:Interleukin-12 Subunit p40 / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D022423:Myeloid Cells / Q000276:immunology* / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: C408982:CPG-oligonucleotide; D004271:DNA, Fungal; D053762:Interleukin-12 Subunit p40; D009838:Oligodeoxyribonucleotides; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9