Research into the molecular pathology of prevalent public health epidemics such as neurodegenerative diseases including frontotemporal dementia (FTD) and Alzheimer’s Disease (AD), non-medical and illicit opioid use (OU), and Human Immunodeficiency Virus-1 (HIV-1) has been hindered by a lack of systems that allow for rapid and high-throughput modeling of the complex multifactorial conditions in a human context. In this thesis we have addressed this challenge using a multi-pronged approach that encompasses single cell RNA sequencing (scRNA-seq) of three-dimensional (3D) human induced pluripotent stem cell (hiPSC) assembloid culture models and patient derived peripheral blood mononuclear cell (PBMC) samples.
We describe the development of an iPSC derived neuron-astrocyte assembloid model of tauopathies, including FTD and AD (AstTau), that rapidly recapitulates propagation of toxic human oligomeric tau (oTau) and cell type specific pathology including misfolded, phosphorylated, oligomeric, and fibrillar tau, strong neurodegeneration, and reactive astrogliosis. scRNA-seq identified vulnerable excitatory neuron specific inflammatory pathways and a heat shock response in astrocytes, recapitulating transcriptomic signatures of adult neurodegeneration and supporting a hypothesis of cell type specific neuroinflammation in tau pathogenesis.
To more completely model AD, we incorporated amyloid precursor protein (APP) mutant iPSCs into the assembloid model. These iPSCs contained the familial AD APP V717I mutation or the isogenic CRISPR corrected control, and were used to derived neurons, astrocytes, and microglia. This advanced combinatorial system (AstAD and MAstAD) enabled selective microglial incorporation, APP mutation expression, and oTau seeding allowing us to identify discrete contributions to AD pathogenesis. Ast/MAstAD developed extracellular amyloid-β (Aβ) and microglial activation in addition to the pathology observed in AstTau. scRNA-seq identified divergent microglial activation in response to Aβ and oTau pathology, with APP V717I mutation and oTau seeding synergistically exacerbating AD phenotypes. These assembloid models enable study of the cellular and molecular inflammatory mechanisms in multifactorial neurodegenerative diseases.
To better understand disease signatures at the crossroads of multifactorial OU, HIV-1, and antiretroviral (ART) viral suppression we also produced a scRNA-seq data set of more than 100,000 peripheral blood mononuclear cells (PBMCs) from 75 study participants. We identified chronic immune activation and T cell activation dysfunction driven by interferon transcriptomic signatures that were elevated in people with HIV (PWH) with opioid use as compared to PWH without OU. We also identified a functional natural killer cell subtype that was depleted with OU in PWH. Cessation of OU reduced these potentially deleterious inflammatory transcriptomic profiles, supporting the hypothesis that OU in PWH amplifies a state of chronic immune activation.
Taken together, single cell transcriptomic resolution has enabled the identification of cell type specific disease signatures in complex pathophysiologies. These data demonstrate the dynamic range of inflammatory signaling across multifactorial disease states and emphasize the need for disease- and cell- type specific approaches to therapeutic development. / 2025-02-05T00:00:00Z
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/48012 |
| Date | 06 February 2024 |
| Creators | Rickner, Hannah Drew |
| Contributors | Cheng, Christine S., Wolozin, Benjamin L. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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