title: Cutting edge: TLR2 directly triggers Th1 effector functions.
abstract: Toll-like receptors recognize pathogen-associated molecular patterns, activate innate immunity, and consequently modulate adaptive immunity in response to infections. TLRs are also expressed on T cells, and it has been shown that T cell activation is modulated by TLR ligands. However, the functions of TLRs on Th1 and Th2 effector cells and the molecular mechanisms underlying TLR-mediated activation are not fully understood. We analyzed TLR functions and downstream signaling events in both effector T cells. In mouse Th1 cells the stimulation by TLR2 but not by other TLRs directly induced IFN-gamma production, cell proliferation, and cell survival without TCR stimulation, and these effects were greatly enhanced by IL-2 or IL-12 through the enhanced activation of MAPKs. In contrast, no TLR affected the function of effector Th2 cells. These results identify TLR2 as a new specific activator of Th1 cell function and imply the involvement in Th1-mediated responses.
authors.affiliation: Laboratory for Cell Signaling, RIKEN Research Center for Allergy and Immunology, Yokohama, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Imanishi
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Hara
authors.forename: Shinobu
authors.initials: S
authors.lastname: Suzuki
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Suzuki
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002470:Cell Survival / Q000276:immunology; D004789:Enzyme Activation / Q000276:immunology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000502:physiology; D007376:Interleukin-2 / Q000502:physiology; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology
chemical_list: D007376:Interleukin-2; D008024:Ligands; D051195:Toll-Like Receptor 2; D018664:Interleukin-12; D007371:Interferon-gamma; D048049:Extracellular Signal-Regulated MAP Kinases