title: Orientia tsutsugamushi infection induces CD4+ T cell activation via human dendritic cell activity.
abstract: Orientia tsutsugamushi, a gram-negative bacterium, causes severe acute febrile illness in humans. Despite this danger, the route of infection, infectivity, and protective mechanisms of the host's immune response to O. tsutsugamushi are unclear. Dendritic cells (DCs) are one of the most important cell types in bridging the innate and adaptive immune responses. In this study, we observed that O. tsutsugamushi infects and replicates in monocyte-derived DCs (MODCs). During infection and replication, the expressions of the cytokines IL-12 and TNF-α, as well as the co-stimulatory molecules CD80, CD83, CD86, and CD40, were increased in MODCs. When O. tsutsugamushi-treated MODCs were co-cultured with autologous CD4(+) T cells, they enhanced production of IFN-γ, a major Th1 cytokine. Collectively, our results show that O. tsutsugamushi can replicate in MODCs and can simultaneously induce MODC maturation and increase proinflammatory cytokine levels in MODCs that subsequently activate CD4(+) T cells.
authors.affiliation: Animal Science and Biotechnology Major and WCU Biomodulation Major, Department of Agricultural Biotechnology, and Research Institute for Agriculture and Life Sciences, and Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Hyuk
authors.initials: H
authors.lastname: Chu
authors.forename: Sung-Moo
authors.initials: SM
authors.lastname: Park
authors.forename: In Su
authors.initials: IS
authors.lastname: Cheon
authors.forename: Mi-Yeoun
authors.initials: MY
authors.lastname: Park
authors.forename: Byoung-Shik
authors.initials: BS
authors.lastname: Shim
authors.forename: Byoung-Cheol
authors.initials: BC
authors.lastname: Gil
authors.forename: Woon Hee
authors.initials: WH
authors.lastname: Jeung
authors.forename: Kyu-Jam
authors.initials: KJ
authors.lastname: Hwang
authors.forename: Ki-Duk
authors.initials: KD
authors.lastname: Song
authors.forename: Kee-Jong
authors.initials: KJ
authors.lastname: Hong
authors.forename: Manki
authors.initials: M
authors.lastname: Song
authors.forename: Hang-Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Han
authors.forename: Cheol-Heui
authors.initials: CH
authors.lastname: Yun
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D003713:Dendritic Cells / Q000276:immunology* / Q000382:microbiology*; D020869:Gene Expression Profiling; D006801:Humans; D012285:Orientia tsutsugamushi / Q000276:immunology*; D012612:Scrub Typhus / Q000276:immunology* / Q000382:microbiology*
chemical_list: D015703:Antigens, CD; D016207:Cytokines