Apoptosis, or programmed cell death, is recognized to play a critical role in the regulation of inflammation, tissue injury, and the host immune response. Recent studies have identified Fas (CD95) as an important cell surface receptor mediating the induction of apoptosis in a wide variety of tissues, including the hematopoietic and immune systems. In contrast to Fas, the expression of its natural ligand, FasL, is relatively restricted. The vast majority of research conducted to date has focused on the Fas/FasL system in lymphocytes and its critical role in lymphoid development. In contrast, relatively little is known regarding the Fas/FasL system in phagocytes and its role in innate immunity and the pathogenesis of acute inflammation and tissue injury. Whereas lymphocytes must be activated to express significant levels of FasL, recent evidence indicates that human neutrophils and monocytes/macrophages constituitively express FasL in an intracellular form which can be mobilized and deployed on the cell surface. Furthermore, these cells can be activated to rapidly release biologically active soluble FasL (sFasL), which, in turn, induces death of heterologous cells. Thus, the Fas/FasL system represents a novel cytokine system with important implications for innate immunity and inflammation. This project will characterize the intracellular storage and functional role of phagocyte-derived FasL, including its interaction with other mediators of phagocyte cytotoxicity and its possible role as a cellular activating (rather than death-inducing) for monocytes/macrophages. The role of the Fas/FasL system in the pathogenesis of acute tissue injury associated with inflammation in vivo will be examined using a model of acute inflammatory lung injury in genetically-defined mice. Acute lung inflammation and injury will be examined in both Fas-deficient (Ipr/lpr) and FasL- deficient (gld/gld) mice, as well as in transgenic lung-epithelial-specific FADD dominant negative mice to assess the contribution of membrane receptor-mediated death pathways to acute lung inflammation. The effect of disruption of the Fas/FasL system on phagocyte survival during acute inflammation in vivo will also be assessed. The project will also investigate whether sFasL is released and functions as a death-inducing cytokine during the course of the acute respiratory distress syndrome (ARDS) in human patients. The long-term objective of this work is to understand the role of cell death in acute inflammation and associated tissue injury. The comprehensive experimental approach described here promises to yield fundamental insights into phagocyte biology, innate host defense, and the pathogenesis of tissue injury during inflammation. Such information may provide the basis for the development of novel therapeutic strategies to limit deleterious sequelae of the immune response in clinical diseases associated with phagocyte infiltration and inflammation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL062995-02
Application #
6390414
Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Harabin, Andrea L
Project Start
2000-04-01
Project End
2005-03-31
Budget Start
2001-04-01
Budget End
2002-03-31
Support Year
2
Fiscal Year
2001
Total Cost
$224,251
Indirect Cost
Name
University of Washington
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
O'Mahony, D Shane; Pham, Uyenvy; Iyer, Ramesh et al. (2008) Differential constitutive and cytokine-modulated expression of human Toll-like receptors in primary neutrophils, monocytes, and macrophages. Int J Med Sci 5:1-8
Li, Jiangning; Pritchard, David K; Wang, Xi et al. (2007) cDNA microarray analysis reveals fundamental differences in the expression profiles of primary human monocytes, monocyte-derived macrophages, and alveolar macrophages. J Leukoc Biol 81:328-35
Nhan, Thomas Q; Liles, W Conrad; Schwartz, Stephen M (2006) Physiological functions of caspases beyond cell death. Am J Pathol 169:729-37
Yaraei, Kambiz; Campbell, Lee Ann; Zhu, Xiaodong et al. (2005) Effect of Chlamydia pneumoniae on cellular ATP content in mouse macrophages: role of Toll-like receptor 2. Infect Immun 73:4323-6
Kassim, Sean Y; Fu, Xiaoyun; Liles, W Conrad et al. (2005) NADPH oxidase restrains the matrix metalloproteinase activity of macrophages. J Biol Chem 280:30201-5
Nhan, Thomas Q; Liles, W Conrad; Schwartz, Stephen M (2005) Role of caspases in death and survival of the plaque macrophage. Arterioscler Thromb Vasc Biol 25:895-903
Hawn, Thomas R; Ozinsky, Adrian; Williams, Luke M et al. (2005) Hyper-IgE syndrome is not associated with defects in several candidate toll-like receptor pathway genes. Hum Immunol 66:842-7
Yaraei, Kambiz; Campbell, Lee Ann; Zhu, Xiaodong et al. (2005) Chlamydia pneumoniae augments the oxidized low-density lipoprotein-induced death of mouse macrophages by a caspase-independent pathway. Infect Immun 73:4315-22
Matute-Bello, Gustavo; Lee, Janet S; Liles, W Conrad et al. (2005) Fas-mediated acute lung injury requires fas expression on nonmyeloid cells of the lung. J Immunol 175:4069-75
Altemeier, William A; Matute-Bello, Gustavo; Gharib, Sina A et al. (2005) Modulation of lipopolysaccharide-induced gene transcription and promotion of lung injury by mechanical ventilation. J Immunol 175:3369-76

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