Submitted June 20, 2006
Accepted November 7, 2006
Engulfment of apoptotic cells by microvascular endothelial
cells induces proinflammatory responses
Torsten Kirsch*, Alexander Woywodt, Michaela Beese, Kristin Wyss, Joon-Keun Park, Uta Erdbruegger, Barbara Hertel, Hermann Haller, and Marion Haubitz
Medical School Hannover, Germany
* Corresponding author; email: tkirsch{at}gmx.net.
Circulating endothelial cells (CEC) have been detected in a variety of vascular disorders but their interactions with healthy endothelium remain unknown. The aim of this study was to evaluate the response of human endothelial cells (EC) to apoptotic or necrotic endothelial cells in an in vitro model and to delineate pathogenetic pathways. Here we show that incubation of human microvascular endothelial cells (HMEC-1) with apoptotic EC resulted in increased expression of chemokines and enhanced binding of leukocytes to HMEC-1 whereas exposure of HMEC-1 to necrotic EC led to no changes in leukocyte binding affinity. Both, apoptotic and necrotic cells were bound and engulfed by HMEC-1 and primary human umbilical vein endothelial cells (HUVEC). We therefore suggest that exposure to apoptotic and necrotic EC induce different patterns of chemokine synthesis and leukocyte adhesion in healthy EC. These data indicate that CEC are not only markers of vascular damage but may induce pro-inflammatory signals in the endothelium.
