Doctor of Philosophy, The Ohio State University, 2024, Biomedical Sciences

Currently, the only cure for hematological malignancies such as leukemia and lymphoma unresponsive to chemotherapy is allogeneic hematopoietic stem cell transplantation (HSCT). However, the success of this procedure as well as broader clinical application is impaired by development of graft-versus-host disease (GVHD). Acute GVHD pathogenesis involves the recognition of host human leukocyte antigen (HLA) mismatched tissues by donor T cells which secrete inflammatory cytokines and carry out direct cytotoxic activities, in particular affecting the skin, liver, and gastrointestinal tract of the transplant recipient. The end-organ damage caused by these alloreactive T cells is frequently fatal making GVHD a leading cause of non-relapse mortality following allogeneic HSCT. Current therapeutic and prophylactic approaches exhibit broad immunosuppressive effects and suboptimal response rates, leaving patients vulnerable to relapse and opportunistic infections. Therefore, novel strategies for treating and preventing acute GVHD are urgently needed. Post-translational modification of histones induces epigenetic changes that can markedly change gene expression and have significant consequences on effector functions. In T cells, these changes may manifest as effects on differentiation of T cell subsets, immunological memory, acquisition of exhausted phenotypes, and function of metabolic pathways, among others. Here, we have focused on two epigenetic architects: protein arginine (R) methyltransferase 5 (PRMT5) and bromodomain and extra-terminal domain (BET) proteins (BRD4). Broadly, we are interested in the role these proteins play in T cell-mediated inflammatory response and their potential as novel therapeutic targets for acute GVHD. As these proteins have been found to be overexpressed in hematological malignancies, we have centered our studies on targeting PRMT5 and BRD4 post-allogeneic HSCT, hypothesizing that these therapeutic approaches would boast additional benefit ove (open full item for complete abstract)

Committee: Parvathi Ranganathan (Advisor); Maria Mihaylova (Committee Member); Aharon Freud (Committee Member); Robert Baiocchi (Committee Member) Subjects: Immunology

Doctor of Philosophy, The Ohio State University, 2020, Pharmaceutical Sciences

Despite novel therapeutic agents and approaches, hematopoietic stem cell transplant (HSCT) is currently the only potential curative therapy for those with advanced blood malignancies, including but not limited to acute myeloblastic and lymphoblastic leukemia, and myelodysplastic syndrome (MDS). HSCT involves the transfer of hematopoietic stem cells from a healthy donor to the patient with compromised bone marrow to reestablish healthy bone marrow function. However, overall survival after HSCT remains to be low, despite improvements in human leukocyte antigen (HLA) matching algorithms, treatment protocols and patient care, hence hindering a wider application of HSCT. Therefore, exploring and understanding the factors that contribute to such toxicities is required to improve outcomes. We explored the contribution of common germline non-HLA genetic variants to post-HSCT survival outcomes herein. We took advantage of Determining the Influence of Susceptibility COnveying Variants Related to one-Year mortality af- ter BMT (DISCOVeRY-BMT) study. DISCOVeRY-BMT study is the first genome- wide study of 3,532 donor-recipient pairs, investigating associations with 1-year sur- vival outcomes after matched unrelated donor HSCT. DISCOVeRY-BMT allowed us to work with a unique dataset that consists of adjudicated survival outcomes, many relevant clinical variables and extensive genome-wide genetic data obtained from SNP and Exome arrays. We took three different approaches to explore such associations: (1) candidate gene, (2) endophenotype and (3) genome-wide. As discussed in Chapter 2, we were unable to validate or replicate previous findings that followed candidate gene approach. We showed that these studies were conducted with much smaller sample sizes and heterogeneous patient populations that possibly contributed to false positive findings. However, we also showed that variants selected for exploring such associations did not have an impact on the gene of interest and hen (open full item for complete abstract)

Committee: Lara Sucheston-Campbell PhD (Advisor); Kellie Archer PhD (Committee Member); Moray Campbell PhD (Committee Member); Daniel Kinnamon PhD (Committee Member) Subjects: Bioinformatics; Biomedical Research; Biostatistics; Epidemiology; Genetics; Pharmacology

Doctor of Philosophy, The Ohio State University, 2018, Comparative and Veterinary Medicine

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a life-saving therapy both for malignant and non-malignant diseases. The success of allo-HSCTs, however, is limited by acute graft-versus-host disease (aGVHD), a frequent complication that remains a leading causes of non-relapse mortality following allo-HSCT. The pathogenesis of aGVHD involves donor T cells which target human leukocyte antigen mismatched host tissues, causing tissue injury through pro-inflammatory cytokine secretion and direct cytotoxicity. The morbidity and mortality associated with aGVHD pose a major barrier against the wider application of allo-HSCT as a curative modality. Thus, better understanding of aGVHD pathogenesis and novel therapeutics are needed. Modulation of T cell function, broadly, depends on control of gene expression. Two well-studied modes of modulating gene expression are noncoding RNAs and epigenetic modifications. Using unbiased approaches, we identified multiple microRNAs that are upregulated during aGVHD. We validated two of these, T-cell intrinsic miR-155 and serum miR-29a, due to their pivotal role in regulating the adaptive immune system. First, we investigate the molecular mechanisms by which miR-155 modulates T cell function in aGVHD. We identify that miR-155 expression in both donor CD8+ T cells and conventional CD4+ CD25- T cells is pivotal for aGVHD pathogenesis. Furthermore, we show that miR-155 strongly impacts alloreactive T cell expansion through proliferation and exhaustion as well as function by promoting a pro-inflammatory Th1 phenotype. Finally, we demonstrate that miR-155 expression in donor T cells regulates chemokine-dependent migration and infiltration into target organs. These findings provide novel insight into the role of miR-155 in regulating T cell function post-transplant and are convincing biological rationale to justify investigation of novel antagomiR-155 therapeutics to prevent or minimize aGVHD. Next, we strive to identify s (open full item for complete abstract)

Committee: Ramiro Garzon MD (Advisor); Michael Caligiuri MD (Committee Member); Renukaradhya Gourapura DVM, MS, PhD (Committee Member); M. Judith Radin DVM, PhD (Committee Member) Subjects: Immunology; Molecular Biology; Oncology

Doctor of Philosophy, Case Western Reserve University, 2015, Biomedical Engineering

Existing imaging modalities for tracking cells in vivo have many limitations such as limited resolution or limited field of view. Cryo-imaging is the only imaging technology that enables cell tracking with single cell sensitivity throughout entire animals in small rodents. It provides cell detection anywhere in mice and determines cell densities far below that which can be observed with any other imaging technologies such as MRI, CT, PET, SPECT and BLI. Using the novel imaging and detection technologies, we explored therapeutic mechanisms of mesenchymal stem cell (MSC) in murine models of graft-versus-host disease (GVHD). Many investigators have found that intravascular infusion of exogenous MSCs improves outcomes of GVHD-induced animals. Although, at least 40 clinical trials are in progress, it is still unclear what the therapeutic mechanism is? In this study, the proposed working hypothesis is that the MSCs specifically go to secondary lymphoid organs (SLOs) in order to suppress alloreactive T-cells proliferation which eventually leads to the attenuation of GVHD. In this study, we show that the hypothesis is indeed the mechanism behind the scene and is testable using our proposed imaging technology and experiments. Firstly, we extended/optimized cryo-imaging technology to detect/analyze/visualize of fluorescently labeled cells (MSCs and T-cells). Secondly, we identified bio-distribution of MSCs in a GVHD mouse model. We found evidence showing that MSCs preferentially co-localize with the effector T-cells in the SLOs after intravenous infusion. Lastly, we observed that MSCs could suppress T-cells proliferation in vivo. Novel T-cell proliferation assays were established to study the effectiveness of the MSC therapy. The assays were developed based on SLO volume enlargement approach and CFSE dilution approach. This project is significant as we have developed a new, important technique for the study of stem cell bio-distribution with single cell sensitivity o (open full item for complete abstract)

Committee: David Wilson PhD (Committee Chair); Kenneth Cooke MD (Committee Member); Andrew Rollins PhD (Committee Member); Vira Chankong PhD (Committee Member); Wouter van't Hof PhD (Committee Member) Subjects: Biomedical Engineering; Biomedical Research; Computer Science; Experiments; Immunology; Medical Imaging

Doctor of Philosophy, The Ohio State University, 2006, Medical Science

Years of clinical and experimental evidence have shown that both the antigen-nonspecific innate immune system and the antigen-specific adaptive immune system can effectively eliminate malignant cells that remain after front-line therapy for cancer. Because the immune response to any given stimulus requires the coordinated activity of a large number of diverse cell types, elaborate communication networks have evolved that utilize direct cell-cell interactions as well as soluble growth factors, or cytokines, that can potentially travel great distances in the body. Knowledge of the mechanisms and effects of these cell-cell and cell-cytokine-cell interactions is of paramount importance as physicians and scientists advance the frontiers of cancer immunotherapy. Presented here is a series of studies that define roles for the cytokine interleukin 15 (IL-15) in acute graft versus host disease (GVHD) and graft rejection. Mediated by both the innate and adaptive immune systems, graft rejection and acute GVHD are the most common life threatening side effects of allogeneic bone marrow transplantation (BMT), a promising immunotherapeutic approach for aggressive and otherwise incurable hematopoietic malignancies. Also presented are studies evaluating a novel therapeutic antibody designed to interrupt the cell-cell signals that serve to prevent tumor cell lysis by natural killer (NK) cells, a critical part of the innate immune system. Together, these data unravel a small portion of the complex interactions between immune effector cells and malignant cells and provide justification for future basic and clinical immunotherapeutic studies.

Committee: Michael Caligiuri (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2004, Medical Microbiology and Immunology

A dysregulated immune system that is either too weak or too strong may lead to disease states such as cancer or autoimmunity. Specifically, this dissertation presents data on a growth factor, interleukin-15 (IL-15), and its pre-clinical application for cancer treatment and its role in the pathophysiology of graft-versus-host disease (GVHD). Provision of tumor-specific T cells, or adoptive immunotherapy, has emerged as a valid approach for prevention or treatment of human cancers such as melanoma and Epstein Barr virus-positive lymphoma. To improve immunotherapy, we hypothesized that IL-15 could be applied as a single agent to enhance tumor immunity through the maintenance of tumor specific CD8+ memory T cells. Tumor-bearing mice were treated with an adoptive transfer of transgenic tumor specific T cells and then randomized to receive daily low dose IL-15 or PBS treatment. Mice receiving tumor-specific T cells and IL-15 experienced a significantly delayed tumor relapse or no relapse at all. Analysis of peripheral blood 21 days after adoptive transfer demonstrated the persistence of tumor specific T cells in mice treated with IL-15 as compared to PBS. These data support the notion that low dose exogenous IL-15 can sustain tumor-specific T cells in vivo and result in clinical benefit. IL-15 is a pleiotropic pro-inflammatory cytokine with inefficient post-transcriptional processing. We hypothesized that alteration of endogenous IL-15 gene regulation could adversely impact disease progression in the well described C57Bl/6 (B6) > (C57Bl/6 x DBA/2)F1 (B6D2F1) murine model of acute allogeneic graft versus host disease (GVHD). B6D2F1 allogeneic recipients were transplanted with B6 bone marrow cells expressing a murine IL-15 transgene (IL-15 tg) modified for efficient translation and secretion. These mice had a dramatically decreased median survival time (MST) compared to mice transplanted with wild type (wt) B6 bone marrow. Blinded analysis of histopathology revealed a signi (open full item for complete abstract)

Committee: Michael Caligiuri (Advisor) Subjects: