Relevanz von Protein Z bei septischer Koagulopathie und Entzündung
Final Report Abstract
Protein Z (PZ) is a 62 kDA vitamin K-dependent coagulation glycoprotein with a molecular structure similar to those of factor VII, IX, X and protein C. However, PZ lacks catalytic activity and serves as a cofactor for the PZ-dependent protease inhibitor (ZPI), a 72 kDA member of the serpin superfamily of protease inhibitors. PZ enhances the inhibition of coagulation factor Xa, and ZPI inhibits factor XIa in a PZ-independent fashion. The (patho)-physiological role and function of PZ and ZPI are incompletely understood, although there is evidence that coagulation factors, including PZ and ZPI are of importance in the crosstalk of inflammation and coagulation for vascular homeostasis. The objective of the grant was to characterize PZ and ZPI in vascular healing processes, ischemia-driven angiogenesis and endothelial response to septic illness. PZ(-/-) mice, which underwent unilateral carotid artery injury, showed significantly increased formation and thickness of the neo-intima with higher numbers of PCNA-positive and alpha-SMA-positive cells and subsequently higher luminal stenosis in carotid arteries compared to PZ(+/+) mice. Furthermore, PZ protein inhibited cell migration in an in vitro wound healing assay with human aortic smooth muscle cells (SMC), while no effect of PZ protein on SMC proliferation was detectable. PZ(-/-) mice exhibited diminished hypoxia-driven neovascularization and reperfusion in post-ischemic murine hind limbs, which was restored by adenoviral PZ gene transfer up to levels seen in PZ(+/+) mice. Further, PZ protein stimulated migratory activity and capillary-like tube formation of endothelial cells comparable to SDF-1. The stimulatory impact of PZ on endothelial cells in vitro was abolished by siRNA targeting against PZ. After knock-down of CXCR4, PZ protein was not able to restore reduced migration. The increased surface expression of CXCR4 on PZ-stimulated endothelial cells and the abrogated restoration of PZ(-/-) mice via AdV-PZ after concomittant treatment with the CXCR4 antagonist AMD3100 supports the idea that PZ mediates angiogenesis via a G-protein coupled pathway and involves the SDF-1/CXCR4 axis. This was underlined by the fact that addition of the G-protein inhibitor pertussis toxin to PZ-stimulated endothelial cells abolished the effect of PZ on capillary-like tube formation. Thus, PZ contributes to a reduced neo-intima formation after vascular injury and plays a role in ischemia-induced angiogenesis, which involves a G-protein coupled pathway and a raised surface expression of CXCR4. Our findings thereby extend the involvement of PZ from the coagulation cascade to a beneficial modulation of vascular homeostasis. In an in vivo murine model of generalized Shwartzman reaction mirroring septic illness, ZPI deficiency enhanced the thrombotic response to vascular injury, whereas PZ deficiency increased inflammatory response. PZ and ZPI might not only regulate thrombosis but are also important regulators of inflammation. We further focus our research in a disease specific manner on the question how these interactions of PZ and ZPI with the coagulation and inflammation cascade can be exploited for the treatment of critically ill patients.
Publications
- Contribution of protein Z and protein Z-dependent protease inhibitor in generalized Shwartzman reaction. Critical Care Medicine, Vol. 41. 2013, Issue 12, pp. e447–e456.
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Butschkau A., Nagel P., Grambow E., Zechner D., Broze G.J. Jr, Vollmar B.
(See online at https://doi.org/10.1097/CCM.0b013e318298a562) - Protein Z Exerts Pro-Angiogenic Effects and Upregulates CXCR4. PLOS ONE, Vol. 9. 2014, Issue 12: e113554.
Butschkau A., Wagner N.M., Genz B., Vollmar B.
(See online at https://doi.org/10.1371/journal.pone.0113554) - Protein Z-deficiency is associated with enhanced neointima formation and inflammatory response after vascular injury in mice.
International Journal of Clinical and Experimental Pathology, Vol. 7. 2014, Issue 9:6064-71.
Butschkau A, Wagner NM, Bierhansl L, Genz B, Vollmar B.
