title: Immunoadjuvant effects of polyadenylic:polyuridylic acids through TLR3 and TLR7.
abstract: Double-stranded RNA (dsRNA) is produced upon viral infection and can activate innate immunity. Polyinosinic:polycytidylic acids [poly(I:C)] is a synthetic mimetic of dsRNA and functions through an endosomal receptor, Toll-like receptor (TLR) 3 or cytosolic receptors. Another type of dsRNA, polyadenylic:polyuridylic acids [poly(A:U)], can also act as an immune adjuvant, but it remains unclear how it exhibits its adjuvant effects. Here, we have characterized the adjuvant effects of poly(A:U). Poly(A:U) could induce both IFN-alpha and IL-12p40 from murine bone marrow dendritic cells (DCs). Poly(A:U)-induced IFN-alpha production depended on a DC subset, plasmacytoid dendritic cell (pDC), and required TLR7. IL-12p40 was also produced by poly(A:U)-stimulated pDC in a TLR7-dependent manner. In addition to pDC, conventional dendritic cell (cDC) also produced IL-12p40 in response to poly(A:U). This IL-12p40 induction resulted from two cDC subsets, CD24(high) cDC and CD11b(high) cDC in a TLR3- and TLR7-dependent manner, respectively. In vivo injection of poly(A:U) with antigen led to clonal expansion of and IFN-gamma production from antigen-specific CD8(+) T cells. Consistent with the in vitro findings, TLR3 and TLR7 were required for the clonal T-cell expansion. Notably, TLR3, rather than TLR7, was critical for generating IFN-gamma-producing CD8(+) T cells. CD8(+) T-cell responses induced by poly(A:U) were independent of type I IFN signaling. Our results demonstrate that poly(A:U) functions as an in vivo immunoadjuvant mainly through TLR3 and TLR7.
authors.affiliation: Laboratory for Host Defense, RIKEN Research Center for Allergy and Immunology, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Hoshino
authors.forename: Masuyoshi
authors.initials: M
authors.lastname: Saito
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yano
authors.forename: Izumi
authors.initials: I
authors.lastname: Sasaki
authors.forename: Chihiro
authors.initials: C
authors.lastname: Yamazaki
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Tsuneyasu
authors.initials: T
authors.lastname: Kaisho
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D016898:Interferon-alpha / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D053762:Interleukin-12 Subunit p40 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011063:Poly A-U / Q000494:pharmacology*; D012330:RNA, Double-Stranded / Q000494:pharmacology; D051196:Toll-Like Receptor 3 / Q000378:metabolism*; D051199:Toll-Like Receptor 7 / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D016898:Interferon-alpha; D053762:Interleukin-12 Subunit p40; D008562:Membrane Glycoproteins; D012330:RNA, Double-Stranded; C519703:TLR3 protein, mouse; C477038:Tlr7 protein, mouse; D051196:Toll-Like Receptor 3; D051199:Toll-Like Receptor 7; D011063:Poly A-U; D007371:Interferon-gamma