Effect of hypoxia/reoxygenation on the cytokine-induced production of nitric oxide and superoxide anion in cultured osteoarthritic synoviocytes.

Abstract

OBJECTIVE:

Hypoxia/reoxygenation (H/R) is an important feature in the osteoarthritis (OA) physiopathology. Nitric oxide (NO) is a significant proinflammatory mediator in the inflamed synovium. The purpose of this study was to investigate the effects of H/R on inducible NO synthase (iNOS) activity and expression in OA synoviocytes. In addition we studied the relationship between nitrosative stress and NADPH oxidase (NOX) in such conditions.

METHODS:

Human cultured synoviocytes from OA patients were treated for 24 h with interleukin 1-β (IL-1β), tumour necrosis factor α (TNF-α) or neither; for the last 6 h, they were submitted to either normoxia or three periods of 1-h of hypoxia followed by 1-h of reoxygenation. ·NO metabolism (iNOS expression, nitrite and peroxynitrite measurements) was investigated. Furthermore, superoxide anion O2(·-) production, NOX subunit expression and nitrosylation were also assessed.

RESULTS:

iNOS expression and nitrite (but not peroxynitrite) production were ~0.20 to ~0.12 nmol min(-1) mg proteins(-1) (P < 0.05), while NOXs' subunit expression and p47-phox phosphorylation were increased. NOXs and p47-phox were dramatically nitrosylated under H/R conditions (P < 0.05 vs normoxia). Using NOS inhibitors under H/R conditions, p47-phox nitrosylation was prevented and O2(·-) production was restored at normoxic levels (0.21 nmol min(-1) mg of proteins(-1)).

CONCLUSIONS:

Our results provide evidence for an up-regulation of iNOS activity in OA synoviocytes under H/R conditions, associated to a down-regulation of NOX activity through nitrosylation. These findings highlight the importance of radical production to OA pathogenesis, and appraise the metabolic modifications of synovial cells under hypoxia.

• Authors: C Chenevier-Gobeaux, C Simonneau, H Lemarechal, D Bonnefont-Rousselot, S Poiraudeau, F Rannou, O G Ekindjian, P Anract, D Borderie
• Journal: Osteoarthritis and cartilage (Osteoarthritis Cartilage) Vol. 21 Issue 6 Pg. 874-81 (Jun 2013) ISSN: 1522-9653 [Electronic] England
• PMID: 23523904 (Publication Type: Journal Article)
• Copyright: Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Interleukin-1beta
• Nitrites
• Tumor Necrosis Factor-alpha
• Superoxides
• Nitric Oxide
• NADPH Oxidases
• Oxygen

Topics

• Aged
• Aged, 80 and over
• Female
• Humans
• Hypoxia (complications)
• Interleukin-1beta (pharmacology)
• Male
• NADPH Oxidases (metabolism)
• Nitric Oxide (metabolism)
• Nitrites (metabolism)
• Osteoarthritis, Knee (metabolism)
• Oxygen (pharmacology)
• Superoxides (metabolism)
• Synovial Membrane (metabolism)
• Tumor Necrosis Factor-alpha (pharmacology)