Angiopoietin-2 sensitizes endothelial cells to TNF-alpha and has a crucial role in the induction of inflammation
- PMID: 16462802
- DOI: 10.1038/nm1351
Angiopoietin-2 sensitizes endothelial cells to TNF-alpha and has a crucial role in the induction of inflammation
Abstract
The angiopoietins Ang-1 and Ang-2 have been identified as ligands of the receptor tyrosine kinase Tie-2 (refs. 1,2). Paracrine Ang-1-mediated activation of Tie-2 acts as a regulator of vessel maturation and vascular quiescence. In turn, the antagonistic ligand Ang-2 acts by an autocrine mechanism and is stored in endothelial Weibel-Palade bodies from where it can be rapidly released upon stimulation. The rapid release of Ang-2 implies functions of the angiopoietin-Tie system beyond its established role during vascular morphogenesis as a regulator of rapid vascular responses. Here we show that mice deficient in Ang-2 (encoded by the gene Angpt2) cannot elicit an inflammatory response in thioglycollate-induced or Staphylococcus aureus-induced peritonitis, or in the dorsal skinfold chamber model. Recombinant Ang-2 restores the inflammation defect in Angpt2(-/-) mice. Intravital microscopy showed normal TNF-alpha-induced leukocyte rolling in the vasculature of Angpt2(-/-)mice, but rolling cells did not firmly adhere to activated endothelium. Cellular experiments showed that Ang-2 promotes adhesion by sensitizing endothelial cells toward TNF-alpha and modulating TNF-alpha-induced expression of endothelial cell adhesion molecules. Together, these findings identify Ang-2 as an autocrine regulator of endothelial cell inflammatory responses. Ang-2 thereby acts as a switch of vascular responsiveness exerting a permissive role for the activities of proinflammatory cytokines.
Comment in
-
Angiogenesis and inflammation face off.Nat Med. 2006 Feb;12(2):171-2. doi: 10.1038/nm0206-171. Nat Med. 2006. PMID: 16462798 No abstract available.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Other Literature Sources
Molecular Biology Databases
Miscellaneous