Date of Award

12-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Bioengineering

Advisor

Dr. Alexey Vertegey

Committee Member

Dr. Frank Alexis

Committee Member

Dr. Ken Webb

Committee Member

Dr. O. Thompson Mefford

Abstract

Chronic obstructive pulmonary disease (COPD) was found to be the fourth leading cause of death in 2004, but current treatments can only relieve the symptoms and improve the quality of life for the patients. Glucocorticoids have been broadly applied in other inflammatory conditions with promising therapeutic effects, but performed poorly in COPD. The phenomenon called glucocorticoid resistance is responsible for glucocorticoid insensitivity in COPD. Researchers have proven that elevated oxidative stress in the lung of a COPD patient is one of the main causes of blocking the function of glucocorticoids. We hypothesize that reducing the oxidative stress in the lung can restore the therapeutic effect of glucocorticoids in COPD. Thus, simultaneous administration of antioxidant and glucocorticoid drugs could be a promising approach to treat this condition. In order to achieve this goal, liposomes loaded with both glucocorticoids and antioxidants were developed and characterized. First, several types of nano-carrier candidates were prepared and tested, and based on the comparative study liposomes were selected as the nano-carrier system of choice for further experiments. In order to quantitatively determine the relationship between the targeting efficacy and the amount of the targeting antibody immobilized on the surface of the liposomes, surface plasmon resonance (SPR) was performed. It was shown that initial increase of the affinity upon the increase of the targeting antibody surface density was followed by the saturation of binding affinity at certain antibody surface density. This saturation surface density was independent regardless of the size of the liposomes or even the type of the targeting antibody and its ligand. This saturation point was important in optimization of the targeting efficacy of the liposomes coated with the targeting antibody. In order to address the glucocorticoid resistance induced by the oxidative stress, and test the hypothesis of the synergistic action of the antioxidant and glucocorticoid drugs, a cell culture model was developed. Exogenous ROS were proven to be necessary in this model. The synergistic effect of the co-delivery of the two drugs was demonstrated by measuring pro-inflammatory response. Analysis of the gene expression of several important biomarkers showed that the mechanism of action involved restoration of the expression of histone deacetylases 2 (HDAC2) in the presence of the antioxidant. Later, this cell culture model also proved the increased drug availability in the case of targeted liposome-based delivery. Overall, this targeted delivery system loaded both antioxidant and glucocorticoid drugs provided another approach to address the problem of treatment of COPD.

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