Date of Award

2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Chemical and Biomolecular Engineering

First Advisor

Scott L. Diamond

Abstract

Certain sterol-based cationic lipids demonstrate both anti-inflammatory and antimicrobial characteristics in addition to their abilities to facilitate gene transfer. These characteristics are particularly suited for enhancing potential gene therapies of cystic fibrosis (CF) airway disease, a condition characterized by chronic infections and concomitant inflammation. Unfortunately, however, animal models of CF do not show the airway disease typically seen in humans, so in vivo efficacies of potential therapies are difficult to assess. In this work, three mouse models were established to evaluate adeno-associated virus (AAV) gene transfer in an infected airway environment. Bordetella bronchiseptica RB50 was used in a chronic, non-lethal respiratory infection model with C57BL/6 mice. Administration of an AAV vector on day 2 of this infection resulted in an approximate three-fold reduction of reporter gene expression, compared to that observed in uninfected controls. Postponement of AAV administration to day 14 resulted in an even greater (eight-fold) reduction in gene expression. Separately, Pseudomonas aeruginosa PAO1 was used to infect surfactant protein D or surfactant protein A knockout mice to establish acute infections. Reporter gene expression was approximately ~2.5-fold lower in these infected mice than in uninfected mice, when AAV was administered on day 2 of infection. Interestingly, when AAV administration was postponed to day 9 of infection in the surfactant protein D knockout model, partial regain in expression was observed. In this case, infection resulted in only a two-fold (vs ~2.5-fold) reduction in gene expression. To reverse these negative effects on gene transfer, six new sterol-based cationic lipids were synthesized and characterized. Of the six lipids tested, two, budesonide spermine and disubstituted budesonide spermine, showed particularly promising in vitro activities and were used to establish proof-of-concept efficacy in an acute infection model. PAO1-infected mice received lipids on day 1 of infection and AAV 24 hours later on day 2. When reporter gene expression was measured one week later, only a ~1.5-1.9-fold reduction in gene expression, compared to the ~2.7-fold reduction seen with untreated controls. Results demonstrate that treatment with dual functioning anti-inflammatory, antimicrobial cationic glucocorticoids can be coordinated with CF gene therapies to restore loss of transduction efficiency caused by active infection.

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