Year of Publication

2012

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Pharmacy

Department

Pharmaceutical Sciences

First Advisor

Dr. David Feola

Second Advisor

Dr. Patrick McNamara

Abstract

Patients with cystic fibrosis who are infected with the pathogen Pseudomonas aeruginosa have shown favorable responses to the drug azithromycin (AZM). This drug works in an anti-inflammatory capacity, improving clinical outcomes and improving quality of life in this population. The drug has also been shown to affect macrophage polarization by shifting these cells away from an inflammatory phenotype toward an alternatively activated anti-inflammatory phenotype. The full impact of this phenotypic change is not well understood in the context of the response to P. aeruginosa infection, or the overall immune response in cystic fibrosis.

To understand how the AZM-polarized macrophage affects other types of cells, we utilized a co-culture in vitro system, with macrophages and fibroblasts incubating together. In this system, we determined that AZM causes upregulation of the pro-fibrotic mediator transforming growth factor-β as well as the extracellular matrix (ECM) protein fibronectin. The mediator of ECM turnover, matrix metalloproteinase (MMP)-9 was upregulated in this system as well. In an in vivo model of P. aeruginosa infection, MMP- 9 and fibronectin were increased in the bronchoalveolar lavage 7 days post-infection in mice that were treated with AZM. This was accompanied by a decrease in damage to the lung tissue, determine by histological examination. To determine if these changes would continue in human subjects with cystic fibrosis, a clinical study was done in this population. Subjects with AZM treatment had decreased TGF-β levels, but no differences in MMP-9 or fibronectin. Interestingly, correlations between certain fibrotic mediators and inflammatory cytokines, specifically interleukin -1β, were different in subjects with AZM treatment compared to subjects without AZM therapy. Together, these data indicate that AZM alters the fibrotic response from the macrophages, as well as the interaction of the inflammatory response and fibrosis development.

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