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Bender H, Noyes N, Annis JL, Hitpas A, Mollnow L, Croak K, Kane S, Wagner K, Dow S, Zabel M. PrPC knockdown by liposome-siRNA-peptide complexes (LSPCs) prolongs survival and normal behavior of prion-infected mice immunotolerant to treatment. PLoS One 2019; 14:e0219995. [PMID: 31329627 PMCID: PMC6645518 DOI: 10.1371/journal.pone.0219995] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/05/2019] [Indexed: 11/29/2022] Open
Abstract
Prion diseases are members of neurodegenerative protein misfolding diseases (NPMDs) that include Alzheimer's, Parkinson's and Huntington diseases, amyotrophic lateral sclerosis, tauopathies, traumatic brain injuries, and chronic traumatic encephalopathies. No known therapeutics extend survival or improve quality of life of humans afflicted with prion disease. We and others developed a new approach to NPMD therapy based on reducing the amount of the normal, host-encoded protein available as substrate for misfolding into pathologic forms, using RNA interference, a catabolic pathway that decreases levels of mRNA encoding a particular protein. We developed a therapeutic delivery system consisting of small interfering RNA (siRNA) complexed to liposomes and addressed to the central nervous system using a targeting peptide derived from rabies virus glycoprotein. These liposome-siRNA-peptide complexes (LSPCs) cross the blood-brain barrier and deliver PrP siRNA to neuronal cells to decrease expression of the normal cellular prion protein, PrPC, which acts as a substrate for prion replication. Here we show that LSPCs can extend survival and improve behavior of prion-infected mice that remain immunotolerant to treatment. LSPC treatment may be a viable therapy for prion and other NPMDs that can improve the quality of life of patients at terminal disease stages.
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Affiliation(s)
- Heather Bender
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Noelle Noyes
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States of America
| | - Jessica L. Annis
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Amanda Hitpas
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Luke Mollnow
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Kendra Croak
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Sarah Kane
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Kaitlyn Wagner
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Steven Dow
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
- Center for Immune and Regenerative Medicine, Department of Clinical Sciences, Colorado State University, Fort Collins, CO, United States of America
| | - Mark Zabel
- Prion Research Center, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, United States of America
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Abstract
The transmissible spongiform encephalopathies are rapidly progressive and invariably fatal neurodegenerative diseases for which there are no proven efficacious treatments. Many approaches have been undertaken to find ways to prevent, halt, or reverse these prion diseases, with limited success to date. However, as both our understanding of pathogenesis and our ability to detect early disease increases, so do our potential therapeutic targets and our chances of finding effective drugs. There is increasing pressure to find effective decontaminants for blood supplies, as variant Creutzfeldt Jakob Disease (vCJD) has been shown to be transmissible by blood, and to find non-toxic preventative therapies, with ongoing cases of Bovine Spongiform Encephalopathy (BSE) and the spread of Chronic Wasting Disease (CWD). Within the realm of chemotherapeutic approaches, much research has focussed on blocking the conversion of the normal form of prion protein (PrP(c)) to its abnormal counterpart (PrP(res)). Structurally, these chemotherapeutic agents are often polyanionic or polycyclic and may directly bind PrP(c) or PrP(res), or act by redistributing, sequestering, or down-regulating PrP(c), thus preventing its conversion. There are also some polycationic compounds which proport to enhance the clearance of PrP(res). Other targets include accessory molecules such as the laminin receptor precursor which influences conversion, or cell signalling molecules which may be required for pathogenesis. Of recent interest are the possible neuroprotective effects of some drugs. Importantly, there is evidence that combining compounds may provide synergistic responses. This review provides an update on current testing methods, therapeutic targets, and promising candidates for chemical-based therapy.
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Affiliation(s)
- Valerie L Sim
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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