Development of Polymeric Nanoparticles and Complementary Diagnostics to Control Aberrant Immune Function

Abstract

A variety of immunological disorders are characterized by inappropriate responses to innocuous protein. This is particularly relevant in autoimmune disease, allergy, and transplant rejection. For these, the therapeutic options that exist are minimal or involve broadly immunosuppressive regimens which are often characterized by undesirable side effects. This dissertation highlights advances in the design of a biodegradable poly-lactide-co-glycolide (PLG) nanoparticle (NP) platform to provide antigen-specific tolerance in these disease models. Strategies to incorporate multiple antigens conjugated to bulk PLG were investigated in a murine model of multiple sclerosis with the observation that a minimum antigen loading of 8µg of antigen per mg of nanoparticle was sufficient to induce maximally observed efficacy. Importantly, this innovation enabled the controlled delivery of multiple antigens to simultaneously treat immunity to multiple antigens. Conjugation of Transforming Growth Factor Beta (TGF-ß) on the surface of these particles while retaining bioactivity represents an improvement to this strategy hypothesized to improve efficacy by promoting induction or expansion of regulatory T cells. Application in a murine model of multiple sclerosis demonstrated improved clinical outcomes with reduced doses, which may be critical to enable clinical translation. Insights gathered from development of these particles were critical to the design of experiments to test the hypothesis that the platform would be safe and effective in murine models of food allergy. Importantly, we demonstrate that it is possible to delivery peanut extract via nanoparticles intravenously without induction of anaphylactic response. Prophylactic and therapeutic administration of particles resulted in improved clinical outcomes and reduction in Th2 markers, including IL-4, IL-5, and IL-13. Interestingly, administration of PLG NPs to deliver allergen did not induce skewing of immunological responses towards Th1/Th17, which is a common approach to treat allergy in pre-clinical models and certain clinical immunotherapy regimens. Studies in a murine model of allogeneic skin transplant rejection demonstrated that the method of incorporation of antigen into the PLG NP resulted in statistically significant delay in graft rejection. These studies also demonstrated shortcomings in the platform’s ability to completely prevent rejection, which we hypothesize is the result of an inability to prevent direct rejection. Development of FasL-conjugated implantable polymeric discs supported the hypothesis that an immunologically privileged site on which to transplant islet cells can delay transplant rejection, which may represent an opportunity to supplement tolerogenic therapies like our PLG NPs. A similar polymeric, implantable technology was designed to enable analysis of the function of inflammatory immune cells, a novel finding which has provided a method to monitor disease progression and response to therapy in a murine model of multiple sclerosis. Collectively, this work has provided several novel strategies to improve polymeric nanoparticle therapies and an implantable, biodegradable platform that shows promise as a complementary diagnostic for therapies that impact immune function, including PLG NPs.