MicroRNA Lipid-Nanoparticle Based Therapy Targets Neuroinflammation and ApoE Dysregulation in Alzheimer's Disease

Abstract MicroRNAs (miRNA) are small non-coding regulatory RNA that have large impacts in health and disease. While prior studies have implicated miRNA in Alzheimer’s disease and associated dementias (ADRD), they have not been used yet in a successful therapeutic strategy. We discovered that microRNA-223 (miR-223), miRNA residing on the X-chromosome which is enriched in microglia/macrophage cells, regulates a sexually dimorphic ApoE pathway via targeting CCAAT-enhancer-binding protein beta (CEBPβ). CEBPβ is an important regulator of neuroinflammatory response and acts as a transcription factor mediating ApoE expression. Our recent data showed that deficiency of miR-223 resulted in a substantial, female-biased elevation of CEBPβ, ApoE, and a heightened inflammatory state in macrophages and in aged mouse brain following a brain injury. Thus, miR-223 appears to regulate a sexually dimorphic microglia/macrophages- dependent increase in inflammation and ApoE as brain cells become activated in parallel with age, injury, and/or Alzheimer’s disease-related pathology. We further demonstrated that miR-223 can be targeted using a novel miRNA-liposome delivery system. Based on these exciting preliminary results, the main goals of this proposal are to test the miR-223-CEBPβ pathway in regulating inflammation-triggered ApoE dysregulation in the biological context of age, sex, and Alzheimer’s disease-relevant brain injury event; and, to test the efficacy of a novel liposome-miRNA delivery method as a potential therapeutic strategy. To complete these objectives, we will 1) confirm that miR-223 directly targets the CEBPβ-ApoE pathway in myeloid cells, and test whether liposome-miR-223 delivery affects this pathway in a novel miR-223 knockout mouse; 2) test the miR-223-CEBPβ-ApoE pathway using a brain injury mouse model and target the pathway using the liposome miRNA delivery system in vivo; 3) evaluate the miR-223- CEBPβ-ApoE pathway in human cells in parallel with neuropathological changes of Alzheimer’s disease. These studies will include assessments of brain tissue from the world-class U.K entucky Alzheimer’s Disease Center biobank. Completion of the funded studies will extend our understanding of mechanisms regulating inflammation/ApoE pathways in the context of sex, aging, and brain injury, ultimately advancing treatments for Alzheimer’s disease. Filling these knowledge gaps could have a lasting impact on public health. Moreover, our innovative miRNA-based therapeutic strategy targeting miR-223 provides a proof of efficacy for a new drug target, particularly in females, who are vulnerable for diseases associated with neuroinflammation and ApoE dysregulation, including Alzheimer’s disease and other brain injury.