title: Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide inhibit T cell-mediated cytotoxicity by inhibiting Fas ligand expression.
abstract: We reported recently that the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) protect CD4+ T cells against Ag-induced apoptosis by down-regulating the expression of Fas ligand (FasL). Because the cytotoxic activity of CD8+ CTLs is mediated through two mechanisms, which involve the perforin/granzyme and the FasL/Fas pathways, in this study we investigated the effects of VIP/PACAP on the generation and activity of allogeneic CTLs, of CD8+ T1 and T2 effector cells and of alloreactive peritoneal exudate cytotoxic T cells (PEL) generated in vivo. VIP/PACAP did not affect perforin/granzyme-mediated cytotoxicity, perforin gene expression, or granzyme B enzymatic activity, but drastically inhibited FasL/Fas-mediated cytotoxicity against allogeneic or syngeneic Fas-bearing targets. VIP/PACAP inhibit CTL generation, but not the activity of competent CTLs. The inhibition is associated with a profound down-regulation of FasL expression, and these effects are mediated through both VPAC1 and VPAC2 receptors. VIP/PACAP inhibit the FasL/Fas-mediated cytotoxicity of T1 effectors and do not affect T2 cytotoxicity, which is entirely perforin/granzyme mediated. Similar effects were observed in vivo. Both the FasL/Fas-mediated cytotoxicity and FasL expression of cytotoxic allogeneic PELs generated in vivo in the presence of VIP or PACAP were significantly reduced. We conclude that, similar to their effect on CD4+ T cells, the two structurally related neuropeptides inhibit FasL expression in CD8+ cytotoxic T cells and the subsequent lysis of Fas-bearing target cells.
authors.affiliation: Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
authors.forename: M
authors.initials: M
authors.lastname: Delgado
authors.forename: D
authors.initials: D
authors.lastname: Ganea
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000276:immunology; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D053222:Fas Ligand Protein; D005260:Female; D006131:Growth Inhibitors / Q000502:physiology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007939:Leukemia L1210; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009479:Neuropeptides / Q000502:physiology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide / Q000502:physiology; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014407:Tumor Cells, Cultured; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism / Q000502:physiology*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: C495402:Adcyap1 protein, mouse; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D006131:Growth Inhibitors; D007166:Immunosuppressive Agents; D008024:Ligands; D008562:Membrane Glycoproteins; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018005:Receptors, Vasoactive Intestinal Peptide; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D019014:fas Receptor; D014660:Vasoactive Intestinal Peptide