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- Title
The Toll-like receptor 7 (TLR7)-specific stimulus loxoribine uncovers a strong relationship within the TLR7, 8 and 9 subfamily.
- Authors
Heil, Florian; Ahmad-Nejad, Parviz; Hemmi, Hiroaki; Hochrein, Hubertus; Ampenberger, Franziska; Gellert, Tanja; Dietrich, Harald; Lipford, Grayson; Takeda, Kiyoshi; Akira, Shizuo; Wagner, Hermann; Bauer, Stefan
- Abstract
Loxoribine (7-allyl-7,8-dihydro-8-oxo-guanosine) acts as synthetic adjuvant in anti-tumor responses. Here we first demonstrate that loxoribine activates cells of the innate immune system selectively via the Toll-like receptor (TLR) 7/MyD88-dependent signaling pathway. TLR7- and MyD88-deficient immune cells fail to proliferate or produce cytokines in response to loxoribine, and genetic complementation of TLR7-deficient cells with murine or human TLR7 confers responsiveness. Subsequently we show that cellular activation by loxoribine and resiquimod (R-848), a stimulus for TLR7 and TLR8, depends on acidification and maturation of endosomes and targets MyD88 to vesicular structures with lysosomal characteristics. This mode of TLR7 and TLR8 action resembles CpG-DNA-driven TLR9 activation. We thus conclude that TLR7, 8 and 9 form a functional subgroup within the TLR family that recognizes pathogen-associated molecular patterns in endosomal/lysosomal compartments.
- Publication
European Journal of Immunology, 2003, Vol 33, Issue 11, p2987
- ISSN
0014-2980
- Publication type
Article
- DOI
10.1002/eji.200324238