Previous work performed under this grant has demonstrated the feasibility of studying collagen biosynthesis and maturation in skin, bone, tendon, and lungs of normal rats by in vivo labelling techniques. The present application proposes to extend these studies into a well documented animal model of pulmonary fibrosis, intra-tracheally injected bleomycin in the rat, to study collagen synthesis and maturation in the damaged, (pre)fibrotic lung. We will specifically test the hypothesis that hydroxylation of key lysine residues that take part in collagen crosslinking reactions is a critical step in the biosynthesis of fibrotic lung collagen. Parallel studies in lung tissue from several animal models and in human fibrotic lungs have demonstrated increased hydroxylation of lysine and an increased ratio of the difunctional Schiff base- derived, crosslink DHLNL to HLNL in (Pre)fibrotic (acute fibrosis) lungs. Similarly, we have observed an increased content of the fully hydroxylated trifunctional crosslink OHP in chronic fibrosis of both animal models and human lungs. Thus, we propose to examine the following hypotheses in this proposal: (i) that increased lysine hydroxylation distinguishes """"""""fibrotic collagen"""""""" from """"""""normal collagen"""""""" in the lung; (ii) that this difference is mediated by increased activity of lysyl hydroxylase in the (pre)fibrotic lung; and (iii) that once crosslinked, """"""""fibrotic collagen"""""""" in the lung is not subject to turnover or breakdown, but rather will persist for the lifetime of the host. A combination of in vivo labelling and tissue slice and homogenate experiments will be performed to examine these questions. Correlative studies with human lung tissue, as available, from patients with acute (ARDS, IRDS) and chronic (IPF) lung fibrosis will examine the underlying mechanisms of collagen accumulation in human lung disease, and will perhaps identify potential new targets for rational therapy of these diseases.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL032690-06
Application #
3344110
Study Section
Pathobiochemistry Study Section (PBC)
Project Start
1985-04-01
Project End
1993-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
6
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Schools of Veterinary Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Gerriets, J E; Reiser, K M; Last, J A (1996) Lung collagen cross-links in rats with experimentally induced pulmonary fibrosis. Biochim Biophys Acta 1316:121-31
Armstrong, L C; Last, J A (1995) Rat lysyl hydroxylase: molecular cloning, mRNA distribution and expression in a baculovirus system. Biochim Biophys Acta 1264:93-102
Sun, W; Wu, R; Last, J A (1994) Coordinated expression of a 45 kD protein and ozone toxicity in a human bronchial epithelial cell line. Am J Respir Cell Mol Biol 10:673-82
Armstrong, L C; Watkins, K; Pinkerton, K E et al. (1994) Collagen mRNA content and distribution in the lungs of rats exposed to ozone. Am J Respir Cell Mol Biol 11:25-34
Gerriets, J E; Curwin, S L; Last, J A (1993) Tendon hypertrophy is associated with increased hydroxylation of nonhelical lysine residues at two specific cross-linking sites in type I collagen. J Biol Chem 268:25553-60
Chen, J; Armstrong, L C; Liu, S J et al. (1991) Silica increases cytosolic free calcium ion concentration of alveolar macrophages in vitro. Toxicol Appl Pharmacol 111:211-20
Buckingham, B; Reiser, K M (1990) Relationship between the content of lysyl oxidase-dependent cross-links in skin collagen, nonenzymatic glycosylation, and long-term complications in type I diabetes mellitus. J Clin Invest 86:1046-54
Last, J A; Gerriets, J E; Armstrong, L C et al. (1990) Hydroxylation of collagen by lungs of rats administered bleomycin. Am J Respir Cell Mol Biol 2:543-8
Last, J A; Armstrong, L G; Reiser, K M (1990) Biosynthesis of collagen crosslinks. Int J Biochem 22:559-64
Last, J A; King Jr, T E; Nerlich, A G et al. (1990) Collagen cross-linking in adult patients with acute and chronic fibrotic lung disease. Molecular markers for fibrotic collagen. Am Rev Respir Dis 141:307-13

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