Saturday, May 10, 2025
5/10/2025
Fibronectin Extra Domain A Degradation as an Antifibrotic Approach in Lung Fibrosis - ABSTRACT This application is for an NHLBI R03 Small Grant Award for K08 Recipients entitled “Fibronectin Extra Domain A Degradation as an Antifibrotic Approach in Lung Fibrosis.” I am a physician in Pulmonary and Critical Care Medicine at the University of Pittsburgh, and I am building a research program focused on the study of basic mechanisms of lung fibrosis with a focus on host protein degradation pathways that could be exploited to mitigate fibrosis. Pulmonary fibrosis is a sequela of several Interstitial lung diseases (ILD) and is characterized pathologically by lung interstitial thickening and excessive deposition of extracellular matrix (ECM) components. Clinically, the development of end-stage lung fibrosis is associated with high morbidity and mortality and the median survival is 3-5 years in patients diagnosed with idiopathic pulmonary fibrosis. While two pharmacotherapies are approved for pulmonary fibrosis from some ILDs, there continues to be an urgent, unmet need for effective therapies to treat chronic fibrotic lung diseases. FN-Extra Domain A (FN-EDA) is a splice variant of the glycoprotein Fibronectin that contains an alternatively-spliced A domain with unique properties. FN-EDA is pathologically enriched in the ECM of patients with chronic fibrosing lung diseases, including idiopathic pulmonary fibrosis and Systemic Sclerosis-Interstitial Lung Disease. FN-EDA is a centerpiece in the “fibro-inflammatory” axis driving aberrant ECM deposition and is a “druggable” target in the pathogenesis of pulmonary fibrosis. The aims of this study are 1) to determine the mechanism of FN-EDA degradation in lung fibroblasts. We will determine if FN-EDA half-life differs in diseased vs. healthy lung fibroblasts and examine if defects in lysosomal FN-EDA degradation account for increased FN-EDA levels in diseased fibroblasts. Mechanistically, we will determine if the EDA domain is modified by ubiquitin to direct FN-EDA degradation. Our second aim is to determine if the repurposed drug Lonafarnib reduces FN-EDA levels and fibrotic responses in vitro and in vivo in a bleomycin-induced model of murine pulmonary fibrosis. We show that the drug lonafarnib increased lysosomal activity and reduces FN-EDA levels in vitro. We will build on this data and determine IC50 values for lonafarnib in vitro in primary lung fibroblasts and human precision-cut lung slices, In vivo, we will use an established model of bleomycin-induced pulmonary fibrosis to test if lonafarnib reduces lung fibrosis. This proposal is a direct result of my K08-specific training plan and activities and builds on our published work examining FN-EDA degradation. I learned high throughput screening methodologies to apply to my research questions as part of my K08 and have developed assays for use in this proposal. This work will inform a larger, more comprehensive R01 proposal in 24 months’ time. My work will be completed within the Division of Pulmonary, Allergy, and Critical Care Medicine at the University of Pittsburgh, which is committed to the development of physician-scientists.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).