Volume 48, Issue 9 pp. 2461-2471
Research Article

Tie2 receptor tyrosine kinase, a major mediator of tumor necrosis factor α–induced angiogenesis in rheumatoid arthritis

Laura M. DeBusk

Laura M. DeBusk

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

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Ying Chen

Ying Chen

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

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Toshihide Nishishita

Toshihide Nishishita

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

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Jin Chen

Jin Chen

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

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James W. Thomas

James W. Thomas

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

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Pengnain Charles Lin

Corresponding Author

Pengnain Charles Lin

Vanderbilt–Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.

Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN 37232.Search for more papers by this author
First published: 11 September 2003
Citations: 79

Abstract

Objective

Rheumatoid arthritis (RA) is an inflammatory disease and an angiogenic disease. However, the molecular mechanisms promoting angiogenesis in RA are not clearly identified. Our objective was to study the role of an endothelium-specific receptor tyrosine kinase, Tie2, in angiogenesis of inflammatory arthritis.

Methods

Expression of Tie2 and its ligand, angiopoietin 1 (Ang1), in human synovium was examined by immunohistochemistry and Western blot. A novel synovium vascular window model was established to study the role of Tie2 in angiogenesis in vivo. Primary cultured endothelial cells and synoviocytes were used to study tumor necrosis factor α (TNFα)–induced Tie2 and Ang1 expression.

Results

Tie2 was implicated in pathologic angiogenesis. We observed that Tie2 and Ang1 were elevated in human RA synovium. Using a novel collagen-induced arthritis synovial window model, we demonstrated that Tie2 signaling regulated arthritis angiogenesis in vivo. We also showed that Tie2 mediated TNFα-induced angiogenesis in a mouse cornea assay. In addition, we observed that TNFα can regulate Tie2 activation in multiple ways that may involve interactions between endothelial cells and synoviocytes. TNFα up-regulates Tie2 in endothelial cells through nuclear factor κB, and it up-regulates Ang1 in synoviocytes. These findings suggest paracrine regulation of angiogenesis between endothelial cells and synoviocytes.

Conclusion

This study demonstrates that Tie2 regulates angiogenesis in inflammatory synovium. Tie2 signaling is an important angiogenic mediator that links the proinflammatory cytokine TNFα to pathologic angiogenesis.

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