Date

2019

Department or Program

Biological Sciences

Primary Wellesley Thesis Advisor

Adam Matthews

Additional Advisor(s)

Elazer Edelman

Additional Advisor

Elise Wilcox

Abstract

Fibrosis is an incurable feature underlying chronic lung and airway diseases including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) that causes partial or total occlusion of the airway with fibrous tissue. In addition to causing these diseases, fibrosis also limits the effectiveness of lung transplants as a long-term treatment for end-stage diseases by causing the complication bronchiolitis obliterans syndrome (BOS). In order to improve our understanding of airway fibrosis, we have developed and characterized an in vitro cell co-culture model composed of airway epithelial cells and blood vessel endothelial cells through which we can induce fibrotic development. This model is more physiologically relevant than previous single cell-type monolayer cultures, as it features interaction between two cell types that are crucial in fibrotic stimulation and development in the airway. We propose a 3D transwell model featuring an air-liquid interface (ALI) as well as a 2D co-culture model with which cell phenotype-specific markers can be visualized with immunofluorescent microscopy.

One step during the progression of fibrosis that can be visualized in this model is epithelial to mesenchymal transition (EMT), which is the shift of epithelial cells to a fibrotic mesenchymal cell-like state. Using the inflammatory cytokine TGFβ1, we are able to induce fibrotic EMT-like phenotypic changes in our 2D cell co-cultures marked by increased intensity in immunostaining for the mesenchymal marker vimentin. We were not able to observe a similar increased intensity for the mesenchymal marker FSP1, nor were we able to observe a reduced intensity for the epithelial marker E-cadherin that have been previously reported to correspond with EMT. Furthermore, we tested treatment of co-cultures with BMP7, an antagonist of EMT, at various points of EMT induction in attempts to reduce fibrotic development. We found that it is only effective in reversing EMT when added after TGFβ1 and can therefore only potentially be used as a post-treatment option.

In this study, we (i) develop a co-culture model with increased physiological relevance to the airway, (ii) characterize effects of TGF-β1 cytokine-induced fibrotic EMT on this model of the airway epithelium, and (iii) characterize the ability of BMP7 to reduce fibrotic EMT when introduced at various time points in the initiation and development of fibrosis.

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