Sickle cell disease (SCD) with associated sickle cell lung injury (SCLI) can lead to the development of chronic sickle cell lung disease (CSCLD). CSCLD is characterized as chronic interstitial lung disease with secondary pulmonary hypertension and fibrosis. The discovery of circulating fibrocytes (CD45+Col1+) has now changed our view on the pathogenesis of pulmonary fibrosis. Fibrocytes play a role in mediating pulmonary fibrosis in pre-clinical models. Fibrocytes are found elevated in the circulation and lungs of IPF patients, and the magnitude of their circulating levels is associated with a worse prognosis in these patients. Extending these findings to SCD, we found using a preclinical transgenic mouse model of human SCD that CXC chemokine receptor 4 (CXCR4) expressing fibrocytes play a significant role in promoting pulmonary fibrosis related to the expression of lung-derived CXCL12. In addition, we found that CXCR4+ fibrocytes were elevated in the circulation of patients with SCD. Based on our preliminary data, we generated an overall hypothesis that fibrocytes play a critical role in mediating the pathogenesis of SCLI and development of CSCLD. To test this postulate, we designed the following specific aims to assess fibrocyte biology at the molecular, cellular, pre-clinical animal model, and patient levels to determine if these cells contribute to SCLI and the development of CSCLD: 1. Correlation of fibrocyte localization in SCD mice with fibrosis and vascular remodeling, and elucidation of the role of CXCL12/CXCR4 in promoting BM expansion, BM mobilization, and extravasation of these cells into the lung during the pathogenesis of SCLI: 2. Determination of mTOR inhibition results in down-regulation of CXCL12/CXCR4 and impairment of fibrocyte extravasation in the lungs that directly correlates with attenuation of the pulmonary vascular remodeling and fibrosis during the pathogenesis of SCLI in transgenic SCD animals. 3. Determine whether fibrocyte number and activated phenotype (i.e., (SMA+ and pSmad2/3+ fibrocytes) are associated with restrictive lung disease in adult SCD patients. Long-term objectives of this project will establish that fibrocytes are critical cells in promoting the pathogenesis of SCLI. These findings will support the notion that strategies to target fibrocytes will lead to novel therapies to attenuate their biology in the pathogenesis of CSCLD.

Public Health Relevance

Sickle cell disease is the most common inherited disorder in African-Americans. While improved patient care in Sickle cell disease has led to increased survival of these patients, they unfortunately experience an increase frequency of chronic organ problems, especially related to the lung. These patients can develop a chronic lung condition that is associated with elevated blood pressure and formation of scar tissue in their lungs. The studies in this proposal will focus on the role of a special cell found in the circulation of patients with sickle cell disease that may contribute to the problems we see in the lungs of these patients.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL098526-02
Application #
8139821
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Goldsmith, Jonathan C
Project Start
2010-09-05
Project End
2014-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
2
Fiscal Year
2011
Total Cost
$495,097
Indirect Cost
Name
University of Virginia
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
065391526
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
Mehrad, Borna; Burdick, Marie D; Wandersee, Nancy J et al. (2017) Circulating fibrocytes as biomarkers of impaired lung function in adults with sickle cell disease. Blood Adv 1:2217-2224
Field, Joshua J; Majerus, Elaine; Gordeuk, Victor R et al. (2017) Randomized phase 2 trial of regadenoson for treatment of acute vaso-occlusive crises in sickle cell disease. Blood Adv 1:1645-1649
Gomez, Diana C; Mehrad, Borna (2016) Eosinophilic pneumonia associated with pirfenidone therapy. Eur Respir J 48:1240-1242
Oremland, Matthew; Michels, Kathryn R; Bettina, Alexandra M et al. (2016) A computational model of invasive aspergillosis in the lung and the role of iron. BMC Syst Biol 10:34
Shipe, Ryan; Burdick, Marie D; Strieter, Brett A et al. (2016) Number, activation, and differentiation of circulating fibrocytes correlate with asthma severity. J Allergy Clin Immunol 137:750-7.e3
Karafin, Matthew S; Dogra, Shibani; Rodeghier, Mark et al. (2016) Increased circulating fibrocytes are associated with higher reticulocyte percent in children with sickle cell anemia. Pediatr Pulmonol 51:295-9
Michels, Kathryn; Nemeth, Elizabeta; Ganz, Tomas et al. (2015) Hepcidin and Host Defense against Infectious Diseases. PLoS Pathog 11:e1004998
Mehrad, Borna; Clark, Nina M; Zhanel, George G et al. (2015) Antimicrobial resistance in hospital-acquired gram-negative bacterial infections. Chest 147:1413-1421
Choi, Young H; Burdick, Marie D; Strieter, Brett A et al. (2014) CXCR4, but not CXCR7, discriminates metastatic behavior in non-small cell lung cancer cells. Mol Cancer Res 12:38-47
Trimble, Aaron; Gochuico, Bernadette R; Markello, Thomas C et al. (2014) Circulating fibrocytes as biomarker of prognosis in Hermansky-Pudlak syndrome. Am J Respir Crit Care Med 190:1395-401

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