title: Nucleic acids of Enterococcus faecalis strain EC-12 are potent Toll-like receptor 7 and 9 ligands inducing interleukin-12 production from murine splenocytes and murine macrophage cell line J774.1.
abstract: In experiment 1 of this study, the interleukin-12 (IL-12)-inducing ability of six Enterococcus strains was evaluated in comparison with that of five Lactobacillus strains using murine splenocytes. At the same time, the involvement of Toll-like receptor (TLR) ligands in IL-12-inducing ability was assessed using splenocytes from TLR2-, TLR4- and MyD88-deficient mice. Most Enterococcus strains, especially Enterococcus faecalis strain EC-12, exerted higher IL-12-inducing ability compared with the Lactobacillus strains evaluated. Almost the same amount of IL-12 protein was produced by all lactic acid bacteria strains in splenocytes from TLR2- and TLR4-deficient mice, whereas splenocytes from MyD88-deficient mice showed no IL-12 production against all bacteria evaluated. In experiment 2, the role of TLR7, 8 and 9 ligands of E. faecalis strain EC-12 in the induction of IL-12 production was evaluated using murine macrophage cell line J774.1. A drastic decrease in IL-12-inducing ability was observed when heat-killed E. faecalis strain EC-12 was treated with nuclease, particularly RNase. In addition, less than one-tenth of IL-12 was produced by heat-killed E. faecalis strain EC-12 when both TLR7 and 9 were antagonized. These facts indicate that the nucleic acids of E. faecalis strain EC-12, particularly its RNA, are the potent TLR7 and 9 ligands that induce IL-12 production from antigen-presenting cells.
authors.affiliation: Laboratory of Animal Science, Kyoto Prefectural University, Shimogamo, Kyoto, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Inoue
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nagino
authors.forename: Go
authors.initials: G
authors.lastname: Hoshino
authors.forename: Kazunari
authors.initials: K
authors.lastname: Ushida
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D002460:Cell Line; D004269:DNA, Bacterial / Q000276:immunology; D013293:Enterococcus faecalis / Q000235:genetics*; D018664:Interleukin-12 / Q000276:immunology*; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000276:immunology; D009696:Nucleic Acids / Q000276:immunology*; D012329:RNA, Bacterial / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000276:immunology*; D051193:Toll-Like Receptors / Q000276:immunology*
chemical_list: D004269:DNA, Bacterial; D008024:Ligands; D053594:Myeloid Differentiation Factor 88; D009696:Nucleic Acids; D012329:RNA, Bacterial; D051193:Toll-Like Receptors; D018664:Interleukin-12