Intranasal gene delivery for Alzheimer’s disease

项目总结/文摘

PROJECT SUMMARY/ABSTRACT Iron overload disorders, including hereditary hemochromatosis (HH) and transfusional hemoglobinopathies (e.g. thalassemia, myelodysplastic syndrome, sickle cell anemia), affect tens of millions of people worldwide. Iron overload is a well-defined risk factor for the development and progression of several metabolic diseases, including cardiomyopathy, liver cirrhosis, arthritis, diabetes and hypertriglyceridemia. Importantly, increased iron stores in the brain are closely associated with neurodegenerative diseases (e.g. Alzheimer’s, Parkinson’s and Huntington’s diseases). Although iron chelators are efficient to remove excess iron from the body, they exhibit significant toxicities, including gastrointestinal bleeding, agranulocytosis, infection, tachycardia, kidney failure and liver fibrosis. Moreover, there is no chelator that effectively restores inappropriately high iron in the brain of patients with neurodegenerative diseases. Hence, there is an unmet need for a new therapeutic strategy by controlling the transport of iron in the brain. Ferroportin (FPN) is the primary iron transporter responsible for the export of intracellular iron. Since FPN is also essential for intestinal iron uptake from diet as well as iron release from the macrophages to recycle the metal for red blood cell production, tissue-specific modulation of FPN can be an excellent therapeutic target to modify brain iron transport with minimal systemic effects. Gene therapy can potentially protect against a number of neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and Huntington’s diseases, by delivering nucleic acid encoding for therapeutic molecules. Conversely, gene silencing selectively decreases the levels of unwanted molecules, such as oncogenic proteins and pro-inflammatory cytokines. We have recently demonstrated that intranasal administration of mRNA in nanoparticles significantly up-regulated protein expression of the reporter genes, such as luciferase and GFP, in the brain. These results suggested that in vivo gene delivery can be exploited in the area of iron disorders, and further prompted us to inquire if a direct delivery of FPN transgene to the brain (site of action) via the intranasal route can mobilize brain iron stores, while avoiding off-target effects. Thus, our hypothesis is that intranasal administration of FPN mRNA in cationic liposomes (CL) enhances brain FPN expression, increases efflux of iron out of the brain and ameliorates iron-induced neuronal impairments. The specific aims are focused on 1) developing and validating FPN transgene/CL to increase brain FPN levels and iron efflux and 2) evaluating the therapeutic efficacy of FPN transgene/CL using a mouse model of iron-associated Alzheimer’s disease. Overall, this strategy provides a selective, effective and safe approach for gene therapy in the area of iron-catalyzed neurodegenerative and other types of neurological disorders.