Thesis Defense Announcement
To: The George Mason University Community
Candidate: Eileen Liberti
Program: M.S. in Biology
Date: Thursday March 29, 2018
Time: 2:00 P.M.
Place: Bull Run Hall, Room 253
George Mason University
Science & Tech Campus
“An In-Vitro Investigation of Glutathione Transferases in Idiopathic Pulmonary Fibrosis”
Committee Chair: Dr. Geraldine Grant
Committee Members: Dr. Charles Madden, Dr. Mikell Paige
This is a public defense and all are invited to attend.
Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial disease of the lung. While pathogenic mechanisms are uncertain, IPF is described as a disease of dysregulated wound repair and is characterized by alveolar epithelial cell (AEC) death and excessive accumulation of activated fibroblasts that produce scarring, impaired gas exchange, eventually leading to death.
Lung tissue by its natural function experiences high oxidative stress. If IPF fibroblasts possess the ability to better metabolize and manage reactive oxygen species (ROS), it will contribute to their survival and progressive fibrosis. This study examines the role that glutathione transferases (GSTs) and GST-pi (GSTP) play in the management of oxidative stress and survival of the IPF fibroblasts.
Using an in vitro model of IPF fibroblast and normal fibroblast, cells were challenged with H2O2 to simulate oxidative stress with and without the GSTP inhibitor, TLK199. Gene expression was assessed by means of quantitative real time polymerase chain reaction (qPCR). GST enzymatic activity was evaluated using a fluorescent substrate reporter for total GST activity.
Increased survival in the presence of H2O2 was observed in IPF fibroblasts compared to normal fibroblasts. This increased survival correlated with higher total GST enzyme activity in IPF fibroblasts. Exposure to the GSTP inhibitor TLK199 in the presence of H2O2 decreased total GST enzyme activity and cell survival bringing IPF fibroblasts in line with normal fibroblasts. Of interest, only IPF fibroblasts manifest a differential response, as indicated by an increase in mRNA levels of GSTP1, GSTA4 and GSTK1 with inhibition of GSTP1 demonstrating a more robust response to oxidative stress.
Our data indicates blocking GSTP mitigates the ability of IPF fibroblasts to evade cell death. These findings establish a key role for GSTs in IPF fibroblast cell survival and ongoing fibrotic activity.