The purpose of this project is to understand the mechanisms of chronic interstitial lung disease by focusing on the interactions of two cytokines, interleukin-1 (IL-1) and tumor necrosis factor (TNF-alpha), with key cell types in a mouse model of fibrosis induced by silica. Reports from us and others demonstrate that IL-1 and TNF-alpha are important in pulmonary fibrosis induced by silica, but their means of action remain unknown. Our new findings support these concepts: increased macrophage production of TNF-alpha and IL-1 in evolving silicosis follow different time courses, and mice genetically deficient in TNF-alpha develop less inflammation and fibrosis after silica exposure than a cytokine-sufficient strain. This research will test the HYPOTHESES that IL-1 and TNF-alpha play critical roles in pulmonary fibrosis through localized effects which (a) perpetuate macrophage activation, (b) promote silicotic lesion formation, (c) stimulate T- lymphocyte proliferation and activation, and (d) cause fibroblasts to replicate. We PROPOSE that these mechanisms are somewhat redundant, and deletion of a single mediator will not prevent fibrosis entirely, but will modify its features and intensity. We shall test these concepts through 3 SPECIFIC AIMS: (1) To define the timing, activity, and localization of gene expression and secretion of pro-inflammatory cytokines (IL-1, TNF-alpha) by pulmonary macrophages following silica exposure of mice, (2) to modulate the immune-inflammatory and/or fibrotic response to silica by interventions which will improve understanding of pathogenetic mechanisms, and (3) To understand the geography of macrophage and lymphocyte location and cytokine expression within the evolving lesion produced by silica or by individual cytokines. We will use mice exposed to a silica aerosol shown to produce interstitial fibrosis, and will compare responses with inert titanium dioxide exposure. We will assess histology, lavage inflammatory cells, and total lung collagen as the outcome of exposures and interventions. We will assess cytokine production by macrophages as bioactivity, protein, and mRNA expression. We will localize the cells responsible for cytokine production in lavage and in tissue by in situ hybridization of mRNA. We will infer function to lymphocytes in lesions from phenotypes detected by immunocytochemistry. We will quantitate tissue responses by image analysis. We will use inbred mouse strains deficient in TNF-alpha, Il-1, or T-cells and new soluble IL-1 and TNF receptors to interdict specific pathways. The novel observations from this work will improve understanding o how activated macrophages recruit and stimulate lymphocytes, how macrophages and lymphocytes amplify pro-inflammatory signals in response to a known inducing agent (silica), and the degree to which deletion of defined communication pathways between cells can interdict the process of pulmonary fibrosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL047069-03
Application #
2223379
Study Section
Lung Biology and Pathology Study Section (LBPA)
Project Start
1993-01-01
Project End
1997-12-31
Budget Start
1995-01-01
Budget End
1995-12-31
Support Year
3
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Vermont & St Agric College
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
066811191
City
Burlington
State
VT
Country
United States
Zip Code
05405
Davis, G S; Holmes, C E; Pfeiffer, L M et al. (2001) Lymphocytes, lymphokines, and silicosis. J Environ Pathol Toxicol Oncol 20 Suppl 1:53-65
Davis, G S; Pfeiffer, L M; Hemenway, D R (2000) Interferon-gamma production by specific lung lymphocyte phenotypes in silicosis in mice. Am J Respir Cell Mol Biol 22:491-501
Antonini, J M; Hemenway, D R; Davis, G S (2000) Quantitative image analysis of lung connective tissue in murine silicosis. Exp Lung Res 26:71-88
Davis, G S; Pfeiffer, L M; Hemenway, D R (1999) Expansion of interferon-gamma-producing lung lymphocytes in mouse silicosis. Am J Respir Cell Mol Biol 20:813-24
Huber, S A; Stone, J E; Wagner Jr, D H et al. (1999) gamma delta+ T cells regulate major histocompatibility complex class II(IA and IE)-dependent susceptibility to coxsackievirus B3-induced autoimmune myocarditis. J Virol 73:5630-6
Davis, G S; Pfeiffer, L M; Hemenway, D R (1998) Persistent overexpression of interleukin-1beta and tumor necrosis factor-alpha in murine silicosis. J Environ Pathol Toxicol Oncol 17:99-114
Davis, G S; Leslie, K O; Hemenway, D R (1998) Silicosis in mice: effects of dose, time, and genetic strain. J Environ Pathol Toxicol Oncol 17:81-97
Garn, H; Friedetzky, A; Davis, G S et al. (1997) T-lymphocyte activation in the enlarged thoracic lymph nodes of rats with silicosis. Am J Respir Cell Mol Biol 16:309-16