Graduation Date

Spring 5-4-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Pharmacology and Experimental Neuroscience

First Advisor

Dr. Yutong Liu

Second Advisor

Dr. Howard Gendelman

Abstract

RATIONALE: Long-acting slow effective release antiretroviral therapy (LASER ART) was developed to improve patient regimen adherence, prevent new infections, and facilitate drug delivery to human immunodeficiency virus cell and tissue reservoirs. However, maintenance of sustained plasma drug levels, for weeks or months, after a single high-level dosing, could improve regimen adherence but, at the same time, affect systemic toxicities. Of these, the most troubling are those that affect the central nervous system (CNS) In an effort to facilitate LASER ART development, “multimodal imaging theranostic nanoprobes” were created. These allow combined bioimaging, drug pharmacokinetics and tissue biodistribution tests in animal models. Additionally, dolutegravir (Tivicay, DTG), in both a native drug form and within a nanoformulations, were administered to mice to investigate potential neurotoxicity or lack thereof in animal models for further LASER ART technology development.

METHODS: Europium (Eu3+)- doped cobalt ferrite (CF) dolutegravir (DTG)- loaded (EuCF-DTG) nanoparticles were synthesized then fully characterized based on their size, shape and stability. These were then used as platforms for nanoformulated drug biodistribution. Rodents were administered parenteral 45-mg/kg doses. DTG-associated changes in CNS homeostasis were assessed by measuring brain metabolic activities. After antiretroviral treatment, brain subregions were dissected and screened by mass spectrometry-based metabolomics.

RESULTS: Folic acid (FA) decoration of EuCF-DTG (FA-EuCF-DTG) nanoparticles facilitated macrophage targeting and sped drug entry across cell barriers. Macrophage uptake was higher for FA-EuCF-DTG than EuCF-DTG nanoparticles with relaxivities of r2 = 546 mM-1 s-1 and r2 = 564 mM-1 s-1 in saline, and r2 = 850 mM-1 s-1 and r2 = mM-1 s-1 in cells, respectively. The values were ten or more times higher than what was observed for ultra-small superparamagnetic iron oxide particles (r2 = 31.15 mM-1 s-1 in saline) using identical iron concentrations. Drug particles were detected in macrophage Rab compartments by dual fluorescence labeling. Replicate particles elicited sustained antiretroviral responses. After parenteral injection of FA-EuCF-DTG and EuCF-DTG into rats and rhesus macaques, drug, iron and cobalt levels, measured by LC-MS/MS, magnetic resonance imaging, and ICP-MS were coordinate. Within metabolomic experimentations, metabolic drug-related dysregulation of energy and oxidative stress were readily observed within the cerebellum and frontal cortex following native drug administrations. Each was associated with alterations in neural homeostasis and depleted canonical oxidation protection pools that included glutathione and ascorbic acid. Surprisingly, the oxidative stress-related metabolites were completely attenuated when DTG was administered as nanoformulations. These data demonstrate the importance of formulation design in control of DTG or perhaps other antiretroviral drug-associated CNS events.

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