Submitted March 24, 2008
Accepted January 15, 2009
C7 is expressed on endothelial cells as a trap for the assembling terminal complement complex and may exert anti-inflammatory function
Fleur Bossi, Lucia Rizzi, Roberta Bulla, Alessandra Debeus, Claudio Tripodo, Paola Picotti, Elena Betto, Paolo Macor, Carlo Pucillo, Reinhard Wurzner, and Francesco Tedesco*
Department of Life Sciences, University of Trieste, Trieste, Italy
Department of Human Pathology, University of Palermo, Palermo, Italy
Institute of Molecular Systems Biology, ETH, Zurich, Switzerland
Department of Science and Biomedical Technology, University of Udine, Udine, Italy
Division of Hygiene and Medical Microbiology, Innsbruck Medical University, Innsbruck, Austria
* Corresponding author; email: tedesco{at}units.it.
We describe a novel localization of C7 as a membrane-bound molecule on endothelial cells (ECs). Data obtained by SDS-PAGE, Western blot, Northern blot and mass spectrometry revealed that membrane-associated C7 (mC7) was indistinguishable from soluble C7 and was associated with vimentin on the cell surface. mC7 interacted with the other late complement components to form membrane-bound TCC (mTCC). Unlike the soluble SC5b-9, mTCC failed to stimulate ECs to express adhesion molecules, to secrete IL-8, and to induce albumin leakage through a monolayer of ECs, and more importantly protected ECs from the pro-inflammatory effect of SC5b-9. Our data disclose the possibility of a novel role of mC7 that acts as a trap for the late complement components to control excessive inflammation induced by SC5b-9.
