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Plasmin-induzierte Aktivierung menschlicher Endothelzellen: Signaltransduktionsmechanismen und funktionelle Bedeutung

Subject Area Pharmacology
Term from 2009 to 2014
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 157463472
 
Final Report Year 2014

Final Report Abstract

Activation of endothelial cells by pro-inflammatory stimuli triggers expression of cellular adhesion molecules such as ICAM-1 on the cell surface, increased adhesion of leukocytes and their trans-endothelial migration marking the key steps in development of atherosclerosis. The serine protease plasmin is generated from its ubiquitously present zymogen during fibrinolysis but also during inflammation. The expression of fibrinolytic genes is increased in the atherosclerotic aorta and correlates with the severity of coronary lesions. We have shown that plasmin activates human inflammatory cells via the annexin A2 heterotetramer. Similar to inflammatory cells, activation of HUVEC by plasmin led to cleavage of the annexin A2 subunit of the receptor complex in lipid rafts, followed by the activation of pro-inflammatory signaling in endothelial cells. Activation of MAPK and the Akt/NF-KB signaling triggered expression of ICAM-1 on endothelial cells and release of soluble ICAM-1. Plasmin cleaves intercellular junctions and VE-cadherin in endothelial cells, inhibits the endothelial cell migration and tube formation, but has no effect on endothelial cell proliferation. DNA microarray analysis revealed plasmin-mediated induction of genes related to the eicosanoid metabolism. In vivo, in human atherosclerotic plaques of human femoral arteries, the endothelial cell marker CD31 is co-localized with the plasmin receptor annexin A2 heterotetramer and ICAM-1. Such plaques also exhibit phosphorylated IKB alpha indicating activation of the NF-KB signaling. Moreover, in advanced atherosclerosis, plasma of patients exhibited enhanced plasmin activity and up-regulated levels of plasmin-alpha2-antiplasmin complexes. These data revealed a new role of plasmin in endothelial cell biology, which could be of particular importance for the identification of new approaches for treatment of atherosclerosis.

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