Judge AD, Bola G, Lee ACH, MacLachlan I. Design of noninflammatory synthetic siRNA mediating potent gene silencing in vivo.
Mol Ther 2005;
13:494-505. [PMID:
16343994 DOI:
10.1016/j.ymthe.2005.11.002]
[Citation(s) in RCA: 413] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Revised: 11/02/2005] [Accepted: 11/04/2005] [Indexed: 11/22/2022] Open
Abstract
Targeted silencing of disease-associated genes by synthetic short interfering RNA (siRNA) holds considerable promise as a novel therapeutic strategy. However, unmodified siRNA can be potent triggers of the innate immune response, particularly when associated with delivery vehicles that facilitate intracellular uptake. This represents a significant barrier to the therapeutic development of siRNA due to toxicity and off-target gene effects associated with this inflammatory response. Here we show that immune stimulation by synthetic siRNA can be completely abrogated by selective incorporation of 2'-O-methyl (2'OMe) uridine or guanosine nucleosides into one strand of the siRNA duplex. These noninflammatory siRNA, containing less than 20% modified nucleotides, can be readily generated without disrupting their gene-silencing activity. We show that, coupled with an effective systemic delivery vehicle, 2'OMe-modified siRNA targeting apolipoprotein B (apoB) can mediate potent silencing of its target mRNA, causing significant decreases in serum apoB and cholesterol. This is achieved at therapeutically viable siRNA doses without cytokine induction, toxicity, or off-target effects associated with the use of unmodified siRNA. This approach to siRNA design and delivery should prove widely applicable and represents an important step in advancing synthetic siRNA into a broad range of therapeutic areas.
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