Fibrotic scarring destroys the delicate architecture of the lung, making normal gas exchange impossible. The types of insults that cause such chronic dysfunction are legion, representing nearly every category of disease. Most, however, share an early common feature: exudation of fibrinogen into the procoagulant-rich distal air spaces. A multitude of events follow, leading eventually either to restoration of normal tissue or to deposition of dense, dysfunctional matrix. The role of the fibroblast in the fibrotic process is central. Although fibrinogen, fibrin, and the fragments which result from their enzymatic cleavage are known to stimulate fibroblast chemotaxis and growth, the specific effects of fibrinogen and its derivatives on different types of lung fibroblasts are poorly understood. The primary goal of the proposed research is to describe the mechanisms by which fibrinogen-derived molecules stimulate proliferation and activation of lung fibroblasts. We hypothesize that lung fibroblasts have specific receptors for portions of the fibrinogen molecule which mediate signals for proliferation alteration of the surrounding matrix and modulation of the local inflammatory response. In testing this hypothesis, we will address three primary questions: * Does fibrin(ogen) stimulate lung fibroblast proliferation directly or indirectly? Rat lung fibroblasts will be cultured in the presence of fibrinogen, fibrin and fibrinolytic peptides or in conditioned media from fibrin(ogen)-stimulated cells. Proliferation assays will determine active moieties. Autocrine loops will be defined by measuring mRNA levels for basic FGF, PDGF and IGF-1, and confirmed by measuring their secretion or by using monoclonal antibodies to block their effects. * How do fibrin(ogen)-stimulated fibroblasts alter the matrix and signal the cells which surround them? Expression and secretion of collagen, metalloproteinase inhibitors, and plasminogen activator inhibitors will be measured to define matrix alteration. Elaboration of the inflammatory cytokines IL-I, IL-6 and IL-8 will be explored. * Do subsets of fibroblasts differ in their response to fibrin(ogen)? Surface display of Thy l antigen distinguishes two different and stable phenotypes of rat lung fibroblasts. We will demonstrate differences in their fibrin(ogen)-induced proliferation and activation by stimulating Thy 1(-) and (+) subpopulations separated by FACS. e results of the proposed research will broaden current understanding of the response of fibroblasts fibrin deposition in the lung.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08HL003239-03
Application #
2027049
Study Section
Special Emphasis Panel (ZHL1-CCT-L (O1))
Project Start
1994-12-01
Project End
1999-11-30
Budget Start
1996-12-01
Budget End
1997-11-30
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Alabama Birmingham
Department
Pediatrics
Type
Schools of Medicine
DUNS #
004514360
City
Birmingham
State
AL
Country
United States
Zip Code
35294
Hagood, James S; Prabhakaran, Priya; Kumbla, Pallavi et al. (2005) Loss of fibroblast Thy-1 expression correlates with lung fibrogenesis. Am J Pathol 167:365-79
Hagood, James S; Mangalwadi, Anandit; Guo, Benliu et al. (2002) Concordant and discordant interleukin-1-mediated signaling in lung fibroblast thy-1 subpopulations. Am J Respir Cell Mol Biol 26:702-8
Barker, T H; Klinger, M M; Feldman, D S et al. (2001) Spectrophotometric analysis for determining the average number of poly(ethylene) glycol molecules on PEGylated proteins utilizing a protein digestion step. Anal Biochem 290:382-5
Olman, M A; Hagood, J S; Simmons, W L et al. (1999) Fibrin fragment induction of plasminogen activator inhibitor transcription is mediated by activator protein-1 through a highly conserved element. Blood 94:2029-38
Hagood, J S; Miller, P J; Lasky, J A et al. (1999) Differential expression of platelet-derived growth factor-alpha receptor by Thy-1(-) and Thy-1(+) lung fibroblasts. Am J Physiol 277:L218-24
Olman, M A; Williams, W F; Strickland Jr, J H et al. (1998) Facile purification of fibrinogen fragments using a computer-based model with general applicability to the generation of salt gradients. Protein Expr Purif 14:71-8
Hagood, J S; Olman, M A; Godoy, J A et al. (1996) Regulation of type I plasminogen activator inhibitor by fibrin degradation products in rat lung fibroblasts. Blood 87:3749-57