title: Targeted delivery of siRNA to macrophages for anti-inflammatory treatment.
abstract: Inflammation mediated by tumor necrosis factor-alpha (TNF-alpha) and the associated neuronal apoptosis characterizes a number of neurologic disorders. Macrophages and microglial cells are believed to be the major source of TNF-alpha in the central nervous system (CNS). Here, we show that suppression of TNF-alpha by targeted delivery of small interfering RNA (siRNA) to macrophage/microglial cells dramatically reduces lipopolysaccharide (LPS)-induced neuroinflammation and neuronal apoptosis in vivo. Because macrophage/microglia express the nicotinic acetylcholine receptor (AchR) on their surface, we used a short AchR-binding peptide derived from the rabies virus glycoprotein (RVG) as a targeting ligand. This peptide was fused to nona-D-arginine residues (RVG-9dR) to enable siRNA binding. RVG-9dR was able to deliver siRNA to induce gene silencing in macrophages and microglia cells from wild type, but not AchR-deficient mice, confirming targeting specificity. Treatment with anti-TNF-alpha siRNA complexed to RVG-9dR achieved efficient silencing of LPS-induced TNF-alpha production by primary macrophages and microglia cells in vitro. Moreover, intravenous injection with RVG-9dR-complexed siRNA in mice reduced the LPS-induced TNF-alpha levels in blood as well as in the brain, leading to a significant reduction in neuronal apoptosis. These results demonstrate that RVG-9dR provides a tool for siRNA delivery to macrophages and microglia and that suppression of TNF-alpha can potentially be used to suppress neuroinflammation in vivo.
authors.affiliation: Center of Excellence in Infectious Diseases, Paul L Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas 79905, USA.
authors.forename: Sang-Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Chunting
authors.initials: C
authors.lastname: Ye
authors.forename: Priti
authors.initials: P
authors.lastname: Kumar
authors.forename: Isaac
authors.initials: I
authors.lastname: Chiu
authors.forename: Sandesh
authors.initials: S
authors.lastname: Subramanya
authors.forename: Haoquan
authors.initials: H
authors.lastname: Wu
authors.forename: Premlata
authors.initials: P
authors.lastname: Shankar
authors.forename: N
authors.initials: N
authors.lastname: Manjunath
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D005434:Flow Cytometry; D020868:Gene Silencing; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000166:cytology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D014764:Viral Proteins