Nitric oxide (NO) is a mediator involved with diverse biological responses including nonspecific defense mechanisms, the regulation of vascular tone and neurotransmission. More recent findings suggest that NO may also regulate cell proliferation and secretory function. In studies addressing the potential role of NO in the pathogenesis of arthritis we have shown that human articular chondrocytes and cartilage tissue but not synoviocytes or inflammatory cells from synovial effusions can be induced to produce NO. In chondrocytes NO synthesis has the characteristics of inducible NO synthase (iNOS) and can be stimulated by proinflammatory cytokines. We cloned the cDNA encoding human chondrocytcs inducible nitric oxide synthase (iNOS). The sequence is identical to that of the human hepatocyte iNOS. We have demonstrated that NO can increase PGE2 production in chondrocytes, mediates the growth inhibitory effects of IL-I and that NO is the major inducer of apoptosis in chondrocytes. Using iNOS as a model, we have characterized signaling pathways that are utilized in the induction of iNOS and provided new insight into IL-I triggered intracellular events. Based on these preliminary findings the specific aims of this study are to (i) study regulation of NO synthesis and expression of the iNOS gene in chondrocyte and cartilage cultures; (ii) evaluate the effects of NO in the regulation of chondrocyte differentiation and secretory function and determine the role of NO in IL-I signal transduction; (iii) analyze iNOS expression in human arthritic cartilage and (iv) study the role of NO in cartilage degradation and chondrocyte apoptosis by using IRF-knock- out-mice which are deficient in iNOS expression. Information generated in these studies will provide new insight into the molecular and cell biology inducible NO synthase, the role of NO in the regulation of chondrocyte function and its contribution to the pathogenesis of cartilage destruction in rheumatoid arthritis and osteoarthritis. The results on the inducible nitric oxide synthase gene and the regulation of its expression have the potential to provide the basis for the development of novel therapeutic interventions against cartilage destruction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR042438-04
Application #
2607915
Study Section
General Medicine A Subcommittee 2 (GMA)
Project Start
1996-03-01
Project End
1999-11-30
Budget Start
1997-12-01
Budget End
1998-11-30
Support Year
4
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Kuhn, Klaus; Lotz, Martin (2003) Mechanisms of sodium nitroprusside-induced death in human chondrocytes. Rheumatol Int 23:241-7
Kuhn, Klaus; Shikhman, Alexander R; Lotz, Martin (2003) Role of nitric oxide, reactive oxygen species, and p38 MAP kinase in the regulation of human chondrocyte apoptosis. J Cell Physiol 197:379-87
Kuhn, K; Lotz, M (2001) Regulation of CD95 (Fas/APO-1)-induced apoptosis in human chondrocytes. Arthritis Rheum 44:1644-53
Kuhn, K; Hashimoto, S; Lotz, M (2000) IL-1 beta protects human chondrocytes from CD95-induced apoptosis. J Immunol 164:2233-9
Lotz, M (1999) The role of nitric oxide in articular cartilage damage. Rheum Dis Clin North Am 25:269-82
Hashimoto, S; Takahashi, K; Ochs, R L et al. (1999) Nitric oxide production and apoptosis in cells of the meniscus during experimental osteoarthritis. Arthritis Rheum 42:2123-31
Hashimoto, S; Takahashi, K; Amiel, D et al. (1998) Chondrocyte apoptosis and nitric oxide production during experimentally induced osteoarthritis. Arthritis Rheum 41:1266-74
Hashimoto, S; Ochs, R L; Komiya, S et al. (1998) Linkage of chondrocyte apoptosis and cartilage degradation in human osteoarthritis. Arthritis Rheum 41:1632-8
Geng, Y; Zhou, L; Thompson, W J et al. (1998) Cyclic GMP and cGMP-binding phosphodiesterase are required for interleukin-1-induced nitric oxide synthesis in human articular chondrocytes. J Biol Chem 273:27484-91
Hashimoto, S; Setareh, M; Ochs, R L et al. (1997) Fas/Fas ligand expression and induction of apoptosis in chondrocytes. Arthritis Rheum 40:1749-55

Showing the most recent 10 out of 11 publications