CD40/CD40L interaction induces E-selectin dependent leukocyte adhesion to human endothelial cells and inhibits endothelial cell migration.
BACKGROUND
CD40 is a receptor expressed on a wide range of cells such as leukocytes and endothelial cells (EC). As a member of the tumor necrosis factor (TNF) superfamily the activation of CD40 by CD40-ligand (CD40L) plays a crucial role for the development and progression of a variety of inflammatory processes including atherosclerosis. The aim of the present study was to investigate the effect of CD40/CD40L interaction on leukocyte adhesion to the endothelium and on endothelial cell migration.


RESULTS
Human umbilical vein endothelial cells (HUVEC) were stimulated with either stable transfectants of mouse myeloma cells expressing the CD40L or wild type cells (4 h). Subsequently adhesion of leukocytes expressing Sialyl Lewis X, the counterpart for E-selectin (HL60 cells), was measured under shear stress (2-2.6 dyne/cm(2)) using a flow chamber adhesion assay. Stimulation of CD40 led to a significant increase of E-selectin dependent adhesion of leukocytes to the endothelium. Incubation of cells with either the CD40L blocking antibody TRAP-1 or the E-selectin blocking antibody BBA2 during CD40 stimulation completely abolished adhesion of leukocytes to HUVEC. Similar results were found in human cardiac microvasculature endothelial cells (HCMEC). In contrast stimulation of CD40 had no effect on adhesion of L-selectin expressing NALM6-L cells. Furthermore, CD40/CD40L interaction abrogated VEGF-induced migration of HUVEC compared to non-stimulated controls. In comparison experiments, stimulation of endothelial cells with VEGF led to a significant phosphorylation of ERK1/2, Akt, and eNOS. Stimulation of endothelial CD40 had no effect on VEGF-induced phosphorylation of ERK1/2. However, VEGF-induced activation of Akt and eNOS was reduced to baseline levels when endothelial CD40 was stimulated.


CONCLUSIONS
CD40/CD40L interaction induces E-selectin dependent adhesion of leukocytes to human endothelial cells and reduces endothelial cell migration by inhibiting the Akt/eNOS signaling pathway.
Department of Medicine/Cardiology, Deutsches Herzzentrum Berlin, Germany.
Daniel
D
Urban
Usan
U
Thanabalasingam
Dietger
D
Stibenz
Jan
J
Kaufmann
Heike
H
Meyborg
Eckart
E
Fleck
Michael
M
Gräfe
Philipp
P
Stawowy
D000818:Animals; D019013:CD40 Antigens / Q000378:metabolism*; D023201:CD40 Ligand / Q000378:metabolism*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D002478:Cells, Cultured; D019040:E-Selectin / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000502:physiology*; D018922:HL-60 Cells; D006801:Humans; D007962:Leukocytes / Q000502:physiology*; D051379:Mice; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000819:agonists; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D019013:CD40 Antigens; D019040:E-Selectin; D042461:Vascular Endothelial Growth Factor A; D023201:CD40 Ligand; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt