Mac-1 and Fas activities are concurrently required for execution of smooth muscle cell death by M-CSF-stimulated macrophages.
OBJECTIVE
We have previously shown that macrophage colony stimulating factor (M-CSF), a potent survival and mitogenic factor for monocytes/macrophages (MM), enables MM to induce vascular smooth muscle cell (VSMC) apoptosis. The killing requires the binding of MM to VSMC via Mac-1 (CD11b/CD18) on MM and intracellular adhesion molecule-1 (ICAM-1) on VSMC. We hypothesized that, in addition to Mac-1 binding, the killing process requires the activation of the Fas-death receptor pathway, which can be blocked at the level of Fas-Fas ligand interaction.


RESULTS
Human peripheral blood monocytes and VSMC were isolated and cultured as previously described. Soluble Fas (sFas) was overexpressed in VSMC by transduction using adenovirus specifying soluble Fas (Ad3hsFas). M-CSF markedly increased the expression of ICAM-1 in VSMC, resulting in enhanced clustering of MM on the surface of VSMC (>/=3 MM per VSMC). MM, but not VSMC, expressed Fas-ligand (FasL), and VSMC apoptosis was inhibited by secretion of sFas by VSMC upon Ad3sFas transduction.


CONCLUSIONS
MM and M-CSF-induced VSMC killing requires MM binding to VSMC mediated by Mac-1 and ICAM-1, and Fas-FasL interaction.
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000704:Analysis of Variance; D017209:Apoptosis; D053148:Caspase 3; D061945:Caspase Inhibitors; D018920:Coculture Techniques; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008262:Macrophage Activation; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology*; D011485:Protein Binding; D013268:Stimulation, Chemical; D014161:Transduction, Genetic; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D016177:Macrophage-1 Antigen; D008562:Membrane Glycoproteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D018799:Intercellular Adhesion Molecule-1; D016173:Macrophage Colony-Stimulating Factor; C505407:CASP3 protein, human; D053148:Caspase 3