Stayton, Patrick S.Su, Fang-Yi2019-02-222019-02-222018Su_washington_0250E_19359.pdfhttp://hdl.handle.net/1773/43300Thesis (Ph.D.)--University of Washington, 2018Pulmonary intracellular infections including tuberculosis, legionellosis, tularemia, and melioidosis present serious global health threats. Those intracellular infections, localized to the lung alveolar macrophage (AM), remain one of the most challenging settings for antimicrobial therapy. Current systemic antibiotic treatment fails to deliver sustained doses to intracellular bacterial reservoirs, which necessitates prolonged treatment regimens. The goal of this thesis is to improve the suboptimal antibiotic treatments by developing targeted polymeric antibiotic therapeutics that can effectively improve the pharmacokinetics (PK) profiles of antibiotics in the lungs and AMs, where the bacteria reside in. This thesis investigated two different drug carrier systems: (1) polymer-augmented liposomes (PALs) to physically encapsulate antibiotics that are not chemically amenable to direct covalent conjugation and (2) polymeric antibiotic prodrugs with varying cleavable linker chemistries to spatially and timely control drug release. All the polymeric carriers used in this study were synthesized by Reversible-Addition Fragmentation chain-Transfer (RAFT) polymerization. Moreover, these carriers were functionalized with mannose residues to target and enhance AM uptake and intracellular delivery. The first part of this thesis demonstrates that the streptomycin-loaded PALs significantly improved intracellular antibacterial activity in a Francisella-macrophage co-culture model, compared to free streptomycin or streptomycin delivered by control PEGylated liposomes. However, PALs showed a typical burst release profile that was suboptimal to sustain drug release in vivo. To achieve better control over drug release kinetics, we engineered a polymeric antibiotic prodrug, termed drugamer, with either enzyme-cleavable dipeptides linker or hydrolytic ester linker. Following intratracheal administration, a single dose of drugamers sustained ciprofloxacin concentration in the lungs and AMs above the minimum inhibitory concentration (MIC) over at least a 48 h period. Notably, the enzyme-cleavable drugamer achieved greater than 10-fold increase in sustained ciprofloxacin dosing in AMs, and maintained significantly higher pharmacokinetic properties in whole lungs as well. Inhalation of drugamers achieved full survival (100%) in a highly lethal mouse model of pneumonic tularemia, contrasted with 0% survival using free ciprofloxacin. Impressively, the enzyme-cleavable drugamer also achieved full protection in a more challenging disease model of pneumonic melioidosis. This model requires a MIC of ciprofloxacin 100x higher than the tularemia model and ciprofloxacin is widely considered ineffective in treating melioidosis clinically. Collectively, these findings demonstrate that the targeted polymeric drugamer therapeutics are highly effective in treating pulmonary intracellular infections and also acts as a useful PK modifier for improving the dosing regimens (e.g., reduce dosage and frequency).application/pdfen-USnoneDrug conjugateEnzyme-cleavable linkerLiposomeMacrophage targetingMelioidosisTularemiaBiomedical engineeringMaterials SciencePharmaceutical sciencesBioengineeringThesis