The broad long-tern objective of this proposal is to understand the role of superoxide in osteoclast-mediated bone resorption. Our relationship between osteoclastic superoxide generation within the ruffled border space and bone resorption; 2. to determine if the effect(s) of superoxide produced in bone is due to superoxide generated within the osteoclastic cellular membrane or outside or both; 3. to determine if a cytokine, Interferon Gamma, known too stimulate superoxide generation in leukocytes from patients with chromic granulomatous disease, enhances osteoclast- mediated bone resorption in and osteopetrotic mouse mutant and if so, to localize the site of action. In these experiments, the effects of superoxide scavengers will be monitored in cultures of isolated osteoclasts and calvaria. Comparing a scavenger which is excluded from cellular membranes by size to a low molecular weight scavenger which permeates membranes, the site of superoxide's effects upon bone resorption will be sought. By using neonatal animals of different ages, we shall assess the importance of the rate of osteoclasts formation upon the mechanism by which oxygen radicals affect bone resorption. NBT staining will be used to measure and localize changes in oxygen radical production in individual osteoclasts. Interferon Gamma will be used to stimulate superoxide generation in osteoclasts from osteopetrotic misc. If Interferon Gamma stimulates osteoclast-mediated bone resorption in tissues cultured from osteopetrotic animals, superoxide scavengers will be added to identical cultures to determine the contribution of superoxide generation to the increased bone resorptive capacity. These experiments have already provides the basis for a phase I/II trial of Interferon Gamma to treat osteopetrotic patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR041463-03
Application #
2080725
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
1991-07-12
Project End
1995-06-30
Budget Start
1993-07-01
Budget End
1995-06-30
Support Year
3
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Medical University of South Carolina
Department
Pediatrics
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
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Madyastha, P R; Yang, S; Ries, W L et al. (2000) IFN-gamma enhances osteoclast generation in cultures of peripheral blood from osteopetrotic patients and normalizes superoxide production. J Interferon Cytokine Res 20:645-52
Yang, S; Hardaway, M; Sun, G et al. (2000) Superoxide generation and tyrosine kinase. Biochem Cell Biol 78:7-Nov
Darden, A G; Ries, W L; Wolf, W C et al. (1996) Osteoclastic superoxide production and bone resorption: stimulation and inhibition by modulators of NADPH oxidase. J Bone Miner Res 11:671-5
Key Jr, L L; Wolf, W C; Gundberg, C M et al. (1994) Superoxide and bone resorption. Bone 15:431-6