Identification and Characterization of Senescent Cells in Molecular Subtypes of Alzheimer's Disease

Alzheimer's disease (AD) remains uncurable. The complex, and diverse, neuropathology suggests that AD may actually represent not a single disease, but a family of diseases that share plaque and tangle neuropathology. The overall modest effects and variability among patients' response to the recent FDA approved drugs for the

treatment of AD highlight potential disease heterogeneity among study subjects. The high heterogeneity of AD has also been strongly supported by the recent discovery of three major molecular subtypes of AD, each possessing distinctive molecular signatures. The therapeutic strategy, referred to as “senolytics,” has gained

immense research attention for its hope to improve various age-associated conditions, including AD and related dementias (ADRD), by pharmacologically removing senescent cells in the brain. Based on our preliminary findings, there is compelling evidence indicating that senescence exhibits distinct characteristics in the major

molecular subtypes of AD. In this application, we propose to systematically investigate the molecular mechanisms of brain senescence in different molecular subtypes of Alzheimer's Disease (AD) for discovery of novel targets and therapeutics for AD. The project will be carried out by a multidisciplinary team of leading

scientists with expertise across translational Sen biology, neuropathology, bioinformatics, systems biology, machine learning and artificial intelligence. We have successfully piloted, and here will deploy, a Sen multi-Omics (senomic) pipeline to define a scale molecular the holistic cellular, molecular and chemical phenotypes of Sen cells in brains from

large number of AD and control subjects. In this project, we will systematically analyze all the existing large- single cell RNA-seq and multiome data in AD to identify and characterize senescent cells in major subtypes of AD. We willvalidate key findings using single-cell multi-Omics and spatial transcriptomics

and imaging in which the entire human transcriptome can be profiled in single cells while maintaining spatial and multi-scale resolution. Using our unique pipeline, we are very well positioned to characterize and quantify the molecular heterogeneity of Sen cells in different AD subtypes. Our iterative approach involves profiling intact

tissues by 10xGenomics Visium and NanoString GeoMx and CosMx platforms as well as disaggregated cells by single nucleus multi-Omics (RNA-seq and ATAC-seq). Results will provide a spatially resolved, comprehensive molecular portrait of both chromatin accessibility, gene and protein expression in the hippocampus in AD in

contrast with healthy control. Our methodologies are non-destructive allowing for mapping multi-analytes back to the tissues to determine cellular morphology and neighborhood environment. We will further develop novel therapeutics against brain senescence in AD through cutting edge drug repositioning approaches. Key driver

genes and candidate drugs will be validated through extensive in vivo experiments. The data and the analytic and experimental tools will be shared with the community for broader investigations.