Doctor of Philosophy, Case Western Reserve University, 2024, Biomedical Engineering

Pancreatic ductal adenocarcinoma (PDAC) presents significant challenges in both diagnosis and treatment due to its aggressive nature and limited therapeutic options. Currently, highly sensitive imaging tools for assessing disease progression and tumor invasion are lacking, exacerbating issues with detection and therapeutic planning. The tumor microenvironment of PDAC plays a substantial role in determining tumor progression and makes staging difficult by establishing pre-metastatic niches. Magnetic resonance molecular imaging (MRMI) is a technique that employs contrast agents targeted to cancer-associated biomarkers. Previously, our lab developed a gadolinium contrast agent targeted to fibronectin for detecting and diagnosing cancerous lesions. In this study, we employed MRMI targeting the oncofetal protein EDB-FN, which is overexpressed in tumors in accordance with stage and grade, to monitor immunotherapies in a mouse model of PDAC. By leveraging the complex tumor microenvironment and targeting fibronectin, a known regulator of PDAC progression, MRMI was able to monitor tumors. Tumors were treated with gene therapy aimed at regulating fibronectin expression, validating that tuning fibronectin and EDB-FN produces discernible changes in MRMI signal. Additionally, in immunotherapy studies, MRMI predicted therapeutic outcomes in mice based on enhancement patterns observed during early treatment phases with novel immunotherapeutic regimens and saline controls. Correlations between signal intensity and changes in tumor response following therapy were identified, enabling classification of mice into responders and non-responders based on immunological studies and histological analysis. These findings demonstrate the potential of MRMI for immunosurveillance in PDAC. It also highlights its ability to non-invasively assess immunotherapy response, thus addressing critical challenges in PDAC management. In doing so, we have built upon existing literature and established EDB-F (open full item for complete abstract)

Committee: Zheng-Rong Lu PhD (Advisor); David Wilson PhD (Committee Chair); Dan Ma PhD (Committee Member); Li Lily Wang PhD (Committee Member); Jordan Winter MD (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Medical Imaging; Oncology

Doctor of Philosophy, The Ohio State University, 2023, Biomedical Sciences

CD4+ T “helper” populations comprise a key subset of adaptive immune cells that are critical for orchestrating antigen-specific immune responses for both the clearance of pathogens and elimination of cancers. This population responds to insult-specific environmental signals, including those from cytokines, by differentiating into a number of functionally distinct subsets, which produce cytokines and interact with additional immune cells to effect their diverse functions. Of these, T follicular helper (TFH) cells are established coordinators of humoral immune responses, as they engage in bi-directional signaling with B cells, via both cell surface receptors and cytokine signals. Ultimately, this interaction is critical for the germinal center reaction, during which B cells are activated, proliferate, and are ultimately selected to support the generation of high-affinity B cell clones, and thus, high-affinity antibodies. This process is also required for the formation of long-lived plasma cell populations, which are a key part of both natural and vaccine-induced immunological memory. In contrast to this important role, TFH cells have also been implicated in autoimmune disorders, including rheumatoid arthritis, systemic lupus erythematosus, and others, for which the production of autoantibodies is a key aspect of pathogenesis. To date, the full scope of mechanisms underlying TFH cell differentiation are incompletely understood. Complicating this process, TFH cells are not comprised of a single, monolithic population, and numerous studies support the existence and function of ‘polyfunctional' TFH populations which exhibit characteristics of other CD4+ T cell subsets (recently reviewed in (1)). Thus, it will be important for TFH-focused work to identify not only shared, but also TFH-subset-specific, regulatory mechanisms. Here, I present findings regarding both cytokine- and transcription-mediated factor mechanisms by which TFH populations are regulated. First, we ide (open full item for complete abstract)

Committee: Kenneth Oestreich Ph.D. (Advisor); Eugene Oltz Ph.D. (Committee Chair); Hazem Ghoneim Ph.D. (Committee Member); Amy Lovett-Racke Ph.D. (Committee Member); Purnima Dubey Ph.D. (Committee Member) Subjects: Immunology; Molecular Biology

Master of Science (MS), Wright State University, 2012, Pharmacology and Toxicology

Peptides with high affinity to the B-cell receptor (BCR) fused to a toxin could be an effective therapy for Chronic Lymphocytic Leukemia (CLL) patients. We screened captured BCR of a CLL patient with peptides from 7 and 12-mer phage display libraries, using two strategies. Lymphocytes from two patients diagnosed with CLL expressing two different unmutated VH genes (VH 1-3 and VH4-34, respectively) were used. Membrane BCRs were obtained from patient CLL cells by lysis, identified by western blot, semi-quantified and screened with phage libraries. The first strategy involved using patient VH4-34 BCRs which were captured using goat anti-human IgM to deplete bound phages. Unbound-phages were positively screened for those binding to patient VH 1-3 BCRs. Several clones were randomly selected and a sequence consisting of “LLPPAR_” peptide was found in both libraries. A phage clone displaying peptide “LLPPARE” was identified to bind to goat anti-human IgM. By including more goat anti-human IgM negative selections, we identified 3 different phages displaying peptides “GFTFMPA”, “QSRPLLP” and “GLPCCSS”. Clones “GFTFMPA” and “GLPCCSS” showed binding to goat anti-human IgM, while “QSRPLLP” did not. Phage clone “QSRPLLP” showed no binding to human serum IgM but showed binding to both patients' BCRs. “QSRPLLP” peptide binds a common BCR molecule region present in both patients but not present in human serum IgM. This data suggests that it is possible to use a peptide-phage display library to select peptides unique for the BCRs of CLL patients. However, the critical component in making this process patient-specific resides in enhanced discrimination in phage selection.

Committee: Osvaldo Lopez PhD (Advisor); Cheryl Conley PhD (Committee Member); David Cool PhD (Committee Member) Subjects: Immunology; Molecular Biology