Grants and Contracts Details
Description
RNA interference by small interfering RNAs (siRNAs) is rapidly b coming the tool
of choice for in vitro and in vivo gene silencing and functional gen mics studies. Its
power stems from ease of use, efficiency, and apparent target speci Icity has led to
therapeutic investigations. However, recent investigations have un overed the ability
of many siRNAs to trigger inflammation via toll like receptor (TL )-3 activation and
interferon induction, independent of their designed target. Nonethe ess the first two
human clinical trials of siRNAs were initiated in an ophthalmic dis ase: neovascular
age-related macular degeneration (AMD), the leading cause ofblin ness among the
elderly on three continents.
We have made the surprising observation that numerous siRNAs ( 10) can suppress
angiogenesis in an animal model of neovascular AMD in a target i dependent fashion.
We found, using Tlr3-I
-, IlIO-/-, III T1
-, Ifnarrl
-, and Ifng-/- mice at an array of
siRNAs targeted against non-mammalian genes, against tissue spe 'fic genes not
expressed in the eye, against random sequences not found in nature and siRNAs that
do not enter the RNA interference silencing complex all trigger TL 3 activation and
induce IL-I 0 and IL-12 expression, thereby suppressing angiogene is by inhibiting
inflammation and endothelial cell proliferation.
We will test the ability of these non-targeted siRNAs to suppress 0 ular angiogenesis
in TlrJ-1
- mice that will be rescued, through adenoviral vector med ated delivery, with
wild-type TLR3 or TLR3 mutants recently discovered not to bind s·RNAs. These
experiments will both confirm the role ofTLR3 in this paradoxical process and also
guide development of small molecule agonists ofTLR3. We will a so test whether the
ability of these non-targeted siRNAs to suppress angiogenesis is a lished in Il ]()-/- X
Ill2-/- mice, as opposed to the partial suppression observed in the 'ngle knockout
mice. These experiments will provide a mechanistic rationale for p rsuing the use IL-
10 and IL-12 as new anti-angiogenic strategies. We also will dete ine whether the
absence of interferon induction and pro-inflammatory cytokine pro uction by these
siRNAs despite TLR3 activation is due to proteolytic cleavage or i tracellular
translocation of MAVS/IPS-liVISAICardif, a transducing protein ecently found to
mediate TLR3-induced interferon induction in RNA viral infectionu.
Collectively these experiments will provide novel information abO
f
t the in vivo
immunology of the generic anti-inflammatory and anti-angiogenic ctivity of siRNAs.
These studies are of great import both for design and interpretation of clinical trials of
siRNAs in ocular angiogenesis, and are relevant to the 70 other dis ases driven by
angiogenesis that affect over 500 million people worldwide.
Status | Finished |
---|---|
Effective start/end date | 7/1/07 → 12/31/13 |
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