Platelet-activating factor mediates CD40-dependent angiogenesis and endothelial-smooth muscle cell interaction.
The aim of the present study was to investigate whether stimulation of CD40 expressed by endothelial or smooth muscle cells triggers the synthesis of platelet-activating factor (PAF), an inflammatory mediator with angiogenic properties, and whether PAF contributes to CD40-induced neoangiogenesis. The results obtained indicate that the interaction of CD40 with soluble CD154 or with CD154 expressed on the membrane of leukocytes (CD154-transfected J558 cells) or of activated platelets, stimulated the synthesis of PAF by endothelial cells but not by smooth cells. The synthesis of PAF triggered by activated platelets was inhibited by a soluble CD40-murine Ig fusion protein that prevents the interaction between membrane CD40 and CD154. Studies with specific inhibitors and evaluation of protein phosphorylation indicated the involvement in PAF synthesis of two intracellular signaling pathways leading to cytosolic phospholipase A(2) activation: a phospholipase Cgamma-protein kinase C-Raf-p42/p44-mitogen-activated protein kinase (MAPK) and a MAPK kinase-3/6-dependent activation of p38 MAPK. PAF synthesized by endothelial cells after CD40 stimulation was instrumental in the in vitro migration and vessel-like organization of endothelial cells, and in the interaction between endothelial cells and smooth muscle cells, as inferred by the inhibitory effect of two different PAF receptor antagonists, WEB2170 and CV3988. In vivo, blockade of PAF receptors prevented the angiogenic effect triggered by CD40 stimulation in a murine model of s.c. Matrigel implantation. In conclusion, these observations indicate that PAF synthesis induced by stimulation of endothelial CD40 contributes to the formation and organization of new vessels. This may be relevant in the vascular remodeling associated with tumor and inflammatory neoangiogenesis.
Russo
Simona
S
Dipartimento di Medicina Interna e di Scienze Cliniche e Biologiche, Università di Torino and Centro Ricerca Medicina Sperimentale, Ospedale San Giovanni Battista, Torino, Italy.
Bussolati
Benedetta
B
Deambrosis
Ilaria
I
Mariano
Filippo
F
Camussi
Giovanni
G
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001381:Azepines / Q000008:administration & dosage; D019013:CD40 Antigens / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D023201:CD40 Ligand / Q000494:pharmacology; D002450:Cell Communication / Q000276:immunology*; D002465:Cell Movement / Q000276:immunology; D002478:Cells, Cultured; D003094:Collagen / Q000008:administration & dosage; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism; D007797:Laminin / Q000008:administration & dosage; D051379:Mice; D008810:Mice, Inbred C57BL; D018448:Models, Immunological; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000276:immunology*; D010972:Platelet Activating Factor / Q000378:metabolism / Q000502:physiology*; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011509:Proteoglycans / Q000008:administration & dosage; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors / Q000378:metabolism; D014230:Triazoles / Q000008:administration & dosage
D000911:Antibodies, Monoclonal; D001381:Azepines; D019013:CD40 Antigens; D004338:Drug Combinations; D007797:Laminin; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011509:Proteoglycans; D043562:Receptors, G-Protein-Coupled; D014230:Triazoles; C039351:platelet activating factor receptor; C059485:matrigel; D023201:CD40 Ligand; D003094:Collagen; C063964:bepafant