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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2008;28:e4.)
© 2008 American Heart Association, Inc.

Letters to the Editor

The Puzzling Role of TRAIL in Endothelial Cell Biology

Paola Secchiero; Giorgio Zauli

Department of Morphology and Embryology, University of Ferrara, Italy

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

In their study published online in Arteriosclerosis, Thrombosis, and Vascular Biology, O’Brien et al demonstrate that activated protein C (APC) decreases tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) expression in endothelial cells.¹ Although the molecular mechanism by which APC decreases the expression of TRAIL mRNA and protein via an Egr-1/Erk-1/2 pathway appears convincing, much less clear is whether the downregulation of TRAIL reflects a physiological relevant decrease of surface TRAIL or TRAIL release by endothelial cells. In fact, we have never detected surface TRAIL by flow cytometry in human umbilical vein endothelial cells (HUVECs), cultured with or without TNF- (Figure). On the other hand, surface TRAIL was easily detectable in other cell model systems, such as peripheral blood-derived adherent macrophages (Figure). Moreover, we were also unable to document in ELISA (R&D System) detectable release of soluble TRAIL by HUVECs treated or not with TNF- (data not shown).

View larger version (15K):   Figure. Surface expression of TRAIL in primary vascular endothelial cells. Surface TRAIL expression was evaluated by flow cytometry in HUVECs cultured with or without TNF-. Surface TRAIL expression in peripheral blood–derived adherent macrophages is shown for comparison. Shadowed histograms represent cells stained with a monoclonal Ab specific for TRAIL (MAB 687, R&D System), whereas unshadowed histogram represents the background fluorescence obtained by staining the same cells with isotype-matched control Ab. A representative of 4 separate experiments is shown.

Because in their study O Brien et al used an ELISA approach to detect the TRAIL . . . [Full Text of this Article]