title: Sequence-dependent stimulation of the mammalian innate immune response by synthetic siRNA.
abstract: Short interfering RNAs (siRNAs) that mediate specific gene silencing through RNA interference (RNAi) are widely used to study gene function and are also being developed for therapeutic applications. Many nucleic acids, including double- (dsRNA) and single-stranded RNA (ssRNA), can stimulate innate cytokine responses in mammals. Despite this, few studies have questioned whether siRNA may have a similar effect on the immune system. This could significantly influence the in vivo application of siRNA owing to off-target effects and toxicities associated with immune stimulation. Here we report that synthetic siRNAs formulated in nonviral delivery vehicles can be potent inducers of interferons and inflammatory cytokines both in vivo in mice and in vitro in human blood. The immunostimulatory activity of formulated siRNAs and the associated toxicities are dependent on the nucleotide sequence. We have identified putative immunostimulatory motifs that have allowed the design of siRNAs that can mediate RNAi but induce minimal immune activation.
authors.affiliation: Protiva Biotherapeutics, 100-3480 Gilmore Way, Burnaby, British Columbia V5G 4Y1, Canada.
authors.forename: Adam D
authors.initials: AD
authors.lastname: Judge
authors.forename: Vandana
authors.initials: V
authors.lastname: Sood
authors.forename: Janet R
authors.initials: JR
authors.lastname: Shaw
authors.forename: Dianne
authors.initials: D
authors.lastname: Fang
authors.forename: Kevin
authors.initials: K
authors.lastname: McClintock
authors.forename: Ian
authors.initials: I
authors.lastname: MacLachlan
mesh_terms: D000818:Animals; D001483:Base Sequence; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects*; D016898:Interferon-alpha / Q000032:analysis; D007371:Interferon-gamma / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D018950:Lipopolysaccharide Receptors / Q000276:immunology; D008081:Liposomes; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D016898:Interferon-alpha; D015850:Interleukin-6; D018950:Lipopolysaccharide Receptors; D008081:Liposomes; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma