Vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide prevent inducible nitric oxide synthase transcription in macrophages by inhibiting NF-kappa B and IFN regulatory factor 1 activation.
High-output nitric oxide (NO) production from activated macrophages, resulting from the induction of inducible NO synthase (iNOS) expression, represents a major mechanism for macrophage cytotoxicity against pathogens. However, despite its beneficial role in host defense, sustained high-output NO production was also implicated in a variety of acute inflammatory diseases and autoimmune diseases. Therefore, the down-regulation of iNOS expression during an inflammatory process plays a significant physiological role. This study examines the role of two immunomodulatory neuropeptides, the vasoactive intestinal peptide (VIP) and the pituitary adenylate cyclase-activating polypeptide (PACAP), on NO production by LPS-, IFN-gamma-, and LPS/IFN-gamma-stimulated peritoneal macrophages and the Raw 264.7 cell line. Both VIP and PACAP inhibit NO production in a dose- and time-dependent manner by reducing iNOS expression at protein and mRNA level. VPAC1, the type 1 VIP receptor, which is constitutively expressed in macrophages, and to a lesser degree VPAC2, the type 2 VIP receptor, which is induced upon macrophage activation, mediate the effect of VIP/PACAP. VIP/PACAP inhibit iNOS expression and activity both in vivo and in vitro. Two transduction pathways appear to be involved, a cAMP-dependent pathway that preferentially inhibits IFN regulatory factor-1 transactivation and a cAMP-independent pathway that blocks NF-kappa B binding to the iNOS promoter. The down-regulation of iNOS expression, together with previously reported inhibitory effects on the production of the proinflammatory cytokines IL-6, TNF-alpha, and IL-12, and the stimulation of the anti-inflammatory IL-10, define VIP and PACAP as "macrophage deactivating factors" with significant physiological relevance.
Delgado
M
M
Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
Munoz-Elias
E J
EJ
Gomariz
R P
RP
Ganea
D
D
D000818:Animals; D000242:Cyclic AMP / Q000502:physiology; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009479:Neuropeptides / Q000494:pharmacology*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D010750:Phosphoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011485:Protein Binding / Q000187:drug effects / Q000276:immunology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism; D018005:Receptors, Vasoactive Intestinal Peptide / Q000502:physiology; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D012772:Shock, Septic / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000276:immunology*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
C495402:Adcyap1 protein, mouse; D004268:DNA-Binding Proteins; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D016328:NF-kappa B; D009479:Neuropeptides; D010750:Phosphoproteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D018005:Receptors, Vasoactive Intestinal Peptide; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D007371:Interferon-gamma; D000242:Cyclic AMP; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse