Browsing by Subject "immune response"

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    Formulation Effects on Immune Response to Nanocarriers Encapsulating TLR 7 Agonist
    (2019-08) Wang, Jiawei
    Abstract Recent decades have witnessed remarkable progress in cancer immunotherapy as an approach to enhancing host immune response against cancer. Particularly, a cancer vaccine comprised of antigen, vaccine adjuvant, and delivery system has gained widespread attention, which can elicit immune response by activating dendritic cells (DCs), the critical antigen-presenting cells (APCs) 1. In the past decades, nanoformulations have gained extensive attention as drug carriers for improved cancer immunotherapy. Imidazoquinoline-based toll-like receptor (TLR) 7 agonist, imiquimod (IMQ), a cytokine inducer, could elicit DC activation. TLR7 activation stimulates myeloid differentiation primary-response gene 88 (MyD88) signaling pathways, elicit DCs to upregulate costimulatory molecules, secrete type I interferons and pro-inflammatory cytokines, and stimulate T cell- mediated immune response 2. The development of a variety of nanoformulations as drug carriers, such as polymeric poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and liposomes, has broadened the application of TLR7 agonist in cancer immunotherapy. However, an improved understanding of how formulation factors could influence the immune response to nanocarriers encapsulating TLR 7 agonist can drive the discovery of more efficient platforms to deliver TLR 7 agonist to immune system for enhanced cancer immunotherapy. In this thesis, we encapsulated IMQ in PLGA NPs that were either naturally anionic or modified with didodecyldimethylammonium bromide (DMAB) to generate cationic surface charge. In addition, 18:0 PC 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dioleoyl-3-trimethylammonium-propane (chloride salt) (DOTAP) were employed to formulate IMQ-loaded anionic DSPC liposomes and cationic DOTAP liposomes. These formulations were evaluated for in vitro DC activation and antigen presentation with a model antigen, ovalbumin (OVA), using bone marrow-derived dendritic cells (BMDCs) and DC 2.4 cell line. Cell viability assay showed that PLGA NPs and DSPC liposomes showed negligible cytotoxicity on BMDCs and DC 2.4 at low concentrations, whereas DMAB-PLGA NPs and DOTAP liposomes exhibited obvious cytotoxicity at relatively low concentrations. Also, anionic PLGA NPs were superior to other nanoformulations in eliciting costimulatory molecule expression by DCs, whereas cationic DOTAP liposomes were superior in inducing antigen presentation by DCs compared with other nanoformulations. Overall, our studies demonstrated that IMQ loaded PLGA NPs showed both better biocompatibility and stronger DC activation efficacy compared with other formulations. However, further studies are needed to understand the mechanism of formulation effects on immune response to nanocarriers encapsulating TLR 7 agonist. Definitely, the development of more efficient drug delivery systems encapsulating TLR agonists could contribute to vaccine-based cancer immunotherapy.
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    Identifying parasite virulence factors and host genetic and immunologic factors that contribute to severe malarial outcomes in Ugandan children
    (2016-10) Shabani, Estela
    Cerebral malaria (CM) and severe malarial anemia (SMA) remain drivers of morbidity and mortality due to Plasmodium falciparum infection in children in Sub-Saharan Africa. There are currently no adjunctive therapies for severe malaria (SM), suggesting that we need a better understanding of both host and pathogen factors that contribute to SM. This dissertation attempted to identify both host and parasite factors that contribute to disease severity in malaria, factors that differentiate between CM and SMA, and those associated with mortality and neurocognitive outcomes in CM. Children between 18 months and 12 years of age, meeting the WHO definition for CM (n=269) or SMA (n=232), were recruited from the Acute Care Unit at Mulago Hospital in Kampala, Uganda. Healthy community children (CC, n=213) in the same age-range were recruited from the neighborhoods and extended households of children with SM. Whole blood was collected at enrollment and was either processed immediately for plasma or was preserved and stored accordingly for future RNA and DNA isolation. We performed genotyping for endothelial protein C receptor (EPCR) polymorphisms, quantitative reverse-transcriptase PCR to estimate transcript levels of var genes encoding P.falciparum erythrocyte membrane protein 1 (PfEMP1), and used plasma to quantify a number of cytokines, chemokines, angiogenic growth factors, soluble EPCR and erythropoietin with ELISA-based assays. The work presented in this dissertation identified both cytoadhesion of infected erythrocytes (IEs) and host immune factors as important contributors to SM pathogenesis. We have shown that polymorphisms associated with less bound and more soluble EPCR are associated with reduced risk of SM; that EPCR-binding PfEMP1 are important in SM and that their transcript levels are higher in CM than SMA; that the immune profile, while quite similar in CM and SMA, is differentiated especially by elevated levels of chemokines and IL-10 in CM. Lastly, our studies on the association of TNF-α and EPO with disease severity in CM highlight the importance of understanding both systemic and local effects of host mediators when considering targets for adjunctive therapies, and the importance of selectively inhibiting the pathogenic effects without compromising the beneficial roles of that target.