Fibrotic lung diseases, including idiopathic pulmonary fibrosis, represent a heterogeneous group of diseases in which progressive parenchymal fibrosis disrupts the structure and gas exchanging functions of the lungs. In the microenvironment of the distal lung, this pathobiology is characterized by an increased population of fibroblasts and augmented collagen and matrix synthesis. In addition to fibroblasts, recent evidence points to a critical role for lung epithelial cells in determining the extent and progression of lung fibrosis. The importance of epithelial cells in fibrogenesis is highlighted by the identification of mutations in the epithelial-restricted gene encoding surfactant protein C (SP-C), that are associated with familial pulmonary fibrosis. While a variety of pathways have been implicated in cross-talk between epithelium and fibroblasts, the critical mechanisms by which epithelial cells influence the effector fibroblast population are not well established. We hypothesize that interactions between lung epithelial cells and fibroblasts determine the severity and progression of lung fibrosis. Specifically, we propose that: 1) epithelial cells, predominantly alveolar type II epithelium, contribute to fibrosis by undergoing epithelial-mesenchymal transition in vivo, 2) epithelial cells regulate proliferation and survival of resident fibroblasts, and 3) phenotypic changes in alveolar type II epithelial cells that cause endoplasmic reticulum stress lead to lung fibrosis by impairing re-epithelialization and inducing an increased population of effector fibroblasts following injury.
Three specific aims are proposed to investigate this hypothesis: 1) to define the extent of epithelial-mesenchymal transition as a source of fibroblasts in experimental pulmonary fibrosis, 2) to determine the pro-fibrotic effects of mutant SP-C expression in alveolar type II epithelial cells, and 3) to investigate the effects of epithelial dysfunction induced by expression of mutant SP-C on fibroblast recruitment/activation and development of lung fibrosis. These studies will use transgenic mice and cell culture systems to define essential roles for epithelial cells in the generation of lung fibrosis. Identifying the impact of alveolar type II epithelial cell phenotype on induction and maintenance of specific populations of effector fibroblasts will provide new insights into the pathogenesis of lung fibrosis and identify new treatment approaches. Relevance to public health: Progressive fibrotic lung diseases frequently lead to respiratory failure and death. These studies will provide a better understanding of the basic mechanisms of disease pathogenesis and suggest new treatment approaches for these devastating diseases.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL085317-05
Application #
8049609
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Eu, Jerry Pc
Project Start
2007-04-10
Project End
2012-03-31
Budget Start
2011-04-01
Budget End
2012-03-31
Support Year
5
Fiscal Year
2011
Total Cost
$383,750
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
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Burman, Ankita; Kropski, Jonathan A; Calvi, Carla L et al. (2018) Localized hypoxia links ER stress to lung fibrosis through induction of C/EBP homologous protein. JCI Insight 3:
Wilfong, Erin M; Lentz, Robert J; Guttentag, Adam et al. (2018) Interstitial Pneumonia With Autoimmune Features: An Emerging Challenge at the Intersection of Rheumatology and Pulmonology. Arthritis Rheumatol 70:1901-1913
Hewlett, Justin C; Kropski, Jonathan A; Blackwell, Timothy S (2018) Idiopathic pulmonary fibrosis: Epithelial-mesenchymal interactions and emerging therapeutic targets. Matrix Biol 71-72:112-127
Kropski, Jonathan A; Blackwell, Timothy S (2018) Endoplasmic reticulum stress in the pathogenesis of fibrotic disease. J Clin Invest 128:64-73
Lentz, Robert J; Taylor, Trevor M; Kropski, Jonathan A et al. (2018) Utility of Flexible Bronchoscopic Cryobiopsy for Diagnosis of Diffuse Parenchymal Lung Diseases. J Bronchology Interv Pulmonol 25:88-96
Sucre, Jennifer M S; Deutsch, Gail H; Jetter, Christopher S et al. (2018) A Shared Pattern of ?-Catenin Activation in Bronchopulmonary Dysplasia and Idiopathic Pulmonary Fibrosis. Am J Pathol 188:853-862
Polosukhin, Vasiliy V; Richmond, Bradley W; Du, Rui-Hong et al. (2017) Secretory IgA Deficiency in Individual Small Airways Is Associated with Persistent Inflammation and Remodeling. Am J Respir Crit Care Med 195:1010-1021
Kropski, Jonathan A; Reiss, Sara; Markin, Cheryl et al. (2017) Rare Genetic Variants in PARN Are Associated with Pulmonary Fibrosis in Families. Am J Respir Crit Care Med 196:1481-1484
Kropski, Jonathan A; Young, Lisa R; Cogan, Joy D et al. (2017) Genetic Evaluation and Testing of Patients and Families with Idiopathic Pulmonary Fibrosis. Am J Respir Crit Care Med 195:1423-1428

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