title: PAFR activation of NF-κB p65 or p105 precursor dictates pro- and anti-inflammatory responses during TLR activation in murine macrophages.
abstract: Platelet-activating factor receptor (PAFR) is a G protein-coupled receptor (GPCR) implicated in many diseases. Toll-like receptors (TLRs) play a critical role in shaping innate and adaptive immune responses. In this study, we investigated whether PAFR signaling changes the macrophages responsiveness to agonists of TLR2 (Pam3Cys), TLR4 (LPS), and TLR3 agonist Poly(I:C). Exogenous PAF inhibited the production of pro-inflammatory cytokines (IL-12p40, IL-6, and TNF-α) and increased anti-inflammatory IL-10 in macrophages challenged with Pam3Cys and LPS, but not with Poly (I:C). PAF did not affect mRNA expression of MyD88, suggesting that PAF acts downstream the adaptor. PAF inhibited LPS-induced phosphorylation of NF-κB p65 and increased NF-κB p105 phosphorylation, which is processed in the proteasome to generate p50 subunit. The PAF potentiation of IL-10 production was dependent on proteasome processing but independent of NF-κB transactivation domain. Inhibition of p50 abolished the PAF-induced IL-10 production. These findings indicate that the impaired transcriptional activity of the p65 subunit and the enhanced p105 phosphorylation induced by PAF are responsible for down regulation of pro-inflammatory cytokines and up regulation of IL-10, respectively, in LPS-challenged macrophages. Together, our data unveil a heretofore unrecognized role for PAFR in modulating activation of NF-κB in macrophages.
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Edson K
authors.initials: EK
authors.lastname: Ishizuka
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Luciano Ribeiro
authors.initials: LR
authors.lastname: Filgueiras
authors.affiliation: Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Rios
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, (46202) United States of America.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Serezani
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Sonia
authors.initials: S
authors.lastname: Jancar
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008074:Lipoproteins / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D052002:NF-kappa B p50 Subunit / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000378:metabolism / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism*
chemical_list: D016207:Cytokines; C556062:IL10 protein, mouse; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D008074:Lipoproteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D052002:NF-kappa B p50 Subunit; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D051996:Transcription Factor RelA; C039351:platelet activating factor receptor; C061108:N-palmitoyl-S-(2,3-bis(palmitoyloxy)propyl)cysteinyl-seryl-lysyl-lysyl-lysyl-lysine; D016753:Interleukin-10; C073701:Nfkb1 protein, mouse