UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item Cell Population Shifts and Clinical Heterogeneity in Sjögren's Disease(2024) Pranzatelli, Thomas J; Johnson, Philip L.F.; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Sjögren's disease (SjD) is a systemic autoimmune disease that causes loss of function of the salivary and lacrimal glands. Those with the disease, overwhelmingly female with an onset of disease in the fourth or fifth decade of life, commonly suffer from dry mouth, cavities and damage to the eyes. Patients present with a wide variety of clinical phenotypes, with variation in degree of immune infiltration and glandular damage as well as positivity for autoantibodies. This thesis uncovers the changes in cell population and gene expression in the gland that underpin diversity in disease severity. SjD patients lose the majority of a specific epithelial population in their labial salivary glands and, as the number of immune infiltrates grows the surviving members of this population can be found colocalizing with invading GZMK+ T cells and expressing markers of increased proliferation. Standard differential gene expression analysis highlighted gene markers of cell types changing in proportion with disease; an unenlightening result when the cell population changes are well-characterized. To avoid this pitfall an ensemble of random forests was trained to find genes predictive of patient subtypes without being correlated with diagnosis. Genes with high importance for autoantibody positivity were enriched for GO terms related to antigen processing and presentation. A master regulator of salivary gland identity, ZBTB7B, was identified from chromatin accessibility data. Mice with this transcription factor knocked out lose salivary flow and develop pockets of tissue in their glands that resemble other glands, eg., labial gland epithelium inside of parotid glands. This work supports a clinical presentation-specific approach to therapy and paves the path for reengineering the glands to correct the effects of disease.Item BIOMATERIALS REPROGRAM ANTIGEN PRESENTING CELLS TO PROMOTE ANTIGEN-SPECIFIC TOLERANCE IN AUTOIMMUNITY(2023) Eppler, Haleigh B; Jewell, Christopher M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The immune system is tightly regulated to balance the killing of disease-causing organisms while protecting host tissue from accidental damage. When this balance is disrupted, immune dysfunctions such as autoimmune diseases occur. Autoimmune diseases like type 1 diabetes and multiple sclerosis (MS) develop when self-tissue is mistakenly attacked and damaged by immune cells. For example, during MS, the immune system mistakenly attacks the myelin sheath that insulates neurons, causing loss of motor function and burdening patients and caregivers. Recent advances in immunotherapies offer exciting new treatments; however, even monoclonal antibody therapies cannot differentiate between healthy and disease-causing cells. Biomaterials provide powerful capabilities to help address these shortcomings. In particular, control over the concentration, duration, location, and combination of signals that are received by immune cells could be transformative in developing more selective immunotherapies that are safe and promote antigen-specific tolerance during autoimmune disease. This dissertation uses two biomaterial approaches to deliver regulatory cargo to antigen presenting cells (APCs). An important APC function is to detect disease-causing organisms by sensing pathogen associated molecular patterns (PAMP) through motif-specific receptors. CpG rich motifs are PAMPs that activate toll-like receptor 9 (TLR9) on DCs and B cells. TLR9 signaling activates B cells and DCs. In MS, TLR9 signaling is aberrantly elevated on certain DCs contributing to systemic inflammation. In MS, B cells signaling through the TLR9 pathwway induced the expression of more inflammatory cytokines as compared to B cells from healthy controls. Controlling this overactive TLR signaling restrains inflammation and is a possible tolerogenic therapeutic approach in MS. The first part of this dissertation uses biomaterials-based polyelectrolyte multilayers (PEMs) to deliver tunable amounts of GpG – an oligonucleotide that inhibits TLR9 signaling – to dendritic cells (DCs). These studies demonstrate that PEMs inhibit DC activation and reduce pathway-specific inflammatory signaling. Furthermore, this work demonstrates that these changes to DCs promote tolerance in downstream T cell development as shown by increasing regulatory T cells. These studies demonstrate this biomaterial delivery system selectively inhibits TLR signaling and DC activation. These changes to DCs promote myelin-specific T cells to adopt a regulatory phenotype, demonstrating a potential approach to developing tolerance inducing antigen-specific immunotherapies for MS. The second part of this dissertation uses a degradable polymer microparticle (MP) system to control the local microenvironment of lymph nodes (LNs). LNs are key sites in the development of immune responses. LNs are composed of different microdomains that coordinate immune cell interactions such as germinal centers (GCs), where B cells develop. These MPs are loaded with myelin self-antigen (MOG35-55) and an mTOR inhibitor, rapamycin (rapa). The MPs are designed to be too large to passively diffuse from the LNs; instead, they slowly degrade releasing encapsulated immune cues to immune cells within the lymph node (LN). Our previous work demonstrates this treatment approach induces antigen-specific tolerance in a preclinical model of MS, but the role of APCs – including DCs and B cells - has not been elucidated. This dissertation reveals that MP treatment alters key LN structural components responsible for interactions between cells in GCs. In addition, MPs alter interactions between B cells/DCs and T cells, as measured by presentation of encapsulated antigen and inhibition of T cell costimulatory molecules by encapsulated rapa. These changes inhibit myelin-specific T cell proliferation and promote regulatory T cells. Finally, B cells from MOG/rapa and MOG MP treated lymph nodes transfer myelin-specific efficacy to mice induced with EAE. These findings illustrate how LN and cellular processes can be regulated by MPs to promote myelin-specific tolerance informing the development of myelin-specific immunotherapies for MS. Together, this body of work provides insight into how biomaterials can be designed to exploit native LN and immune cell functions in the design of next-generation approaches to safely induce myelin-specific tolerance during MS or other autoimmune diseases.Item Engineering biomaterials to promote systemic, antigen-specific tolerance(2017) Tostanoski, Lisa Hoban; Jewell, Christopher M; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In autoimmune diseases, such as multiple sclerosis (MS) and type 1 diabetes, the immune system incorrectly identifies and attacks “self” molecules. Existing therapies have provided important benefits, but are limited by off-target effects, reduced efficacy as disease progresses, and lack of cure potential, necessitating frequent, life-long dosing. An exciting strategy being explored is the design of vaccine-like therapies that selectively reprogram immune responses to self-molecules. This approach could, for example, control the attack of myelin – the protective coating around neurons – that occurs during MS, without leaving patients immunocompromised. However, the realization of this idea has proven difficult; once injected, conventional approaches do not provide control over the combinations, concentrations, and kinetics of signals that reach key tissues that orchestrate immune responses, such as lymph nodes (LNs). Biomaterials have emerged as a promising strategy to confront this challenge, offering features including co-delivery of cargos and controlled release kinetics. The research in this dissertation harnesses biomaterials to develop novel strategies to promote effective, yet selective control of autoimmunity, termed antigen-specific tolerance. In the first aim, direct injection was used to deposit degradable microparticles in LNs, enabling local controlled release of combinations of myelin peptide and Rapamycin, a drug shown to promote regulatory immune function. This work demonstrates the potency of intra-LN delivery in mouse models of MS, as a single dose of co-loaded microparticles permanently reversed disease-induced paralysis in a myelin-specific manner. The results also support this approach as a platform to study the link between local LN signaling and resultant responses in non-treated tissues and sites of disease during autoimmunity. In the second aim, myelin peptide and GpG, a regulatory ligand of an inflammatory pathway overactive in mouse models and patients with autoimmunity, were self-assembled. This approach generated microcapsules that mimic attractive features of conventional biomaterials, but eliminate synthetic carrier components that can complicate rational design and, due to intrinsic inflammatory properties, might exacerbate autoimmunity. These materials promoted tolerance in mouse cells, mouse models of MS, and samples from human MS patients. Together, these strategies could offer novel, modular approaches to combat autoimmune diseases and inform design criteria for future therapies.