title: Retinoic acid receptor agonist Am80 inhibits CXCL2 production from microglial BV-2 cells via attenuation of NF-κB signaling.
abstract: Accumulating lines of evidence suggest that retinoic acid receptor agonists such as Am80 exerts anti-inflammatory actions in the central nervous system, although detailed mechanisms of the action remain largely unknown. Our previous findings suggest that Am80 provides therapeutic effect on intracerebral hemorrhage in mice via suppression of expression of chemokine (C-X-C motif) ligand 2 (CXCL2). Here we investigated the mechanisms of inhibitory action of Am80 on expression of CXCL2 and other pro-inflammatory factors in microglial BV-2 cells. Pretreatment with Am80 markedly suppressed lipopolysaccharide (LPS)-induced expression of CXCL2 mRNA and release of CXCL2 protein. Am80 had no effect on LPS-induced activation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase. On the other hand, Am80 prevented LPS-induced nuclear translocation of p65 subunit of NF-κB complex. In addition, total expression levels of p65 and IκBα proteins, as well as of mRNAs encoding p65 and IκBα, were lowered by Am80. Dependence of CXCL2 expression on NF-κB was confirmed by the effect of an NF-κB inhibitor caffeic acid phenethyl ester that abolished LPS-induced CXCL2 expression. Caffeic acid phenethyl ester also abolished LPS-induced expression of inducible nitric oxide synthase, interleukin-1β and tumor necrosis factor α, which may be relevant to the inhibitory effect of Am80 on expression of these pro-inflammatory factors. We additionally found that Am80 attenuated LPS-induced up-regulation of CD14, a co-receptor for Toll-like receptor 4 (TLR4). These results suggest that inhibitory effect on TLR4 signaling mediated by NF-κB pathway underlies the anti-inflammatory action of retinoic acid receptor agonists in microglia.
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Takaoka
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Moeka
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kurauchi
authors.affiliation: Priority Organization for Innovation and Excellence, Kumamoto University, Kumamoto, Japan; Program for Leading Graduate Schools "HIGO (Health life science: Interdisciplinary and Glocal Oriented) Program", Kumamoto University, Kumamoto, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Hisatsune
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Seki
authors.affiliation: Research Foundation Itsuu Laboratory, Tokyo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Shudo
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan. Electronic address: hkatsuki@gpo.kumamoto-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katsuki
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001565:Benzoates / Q000494:pharmacology*; D002460:Cell Line; D054426:Chemokine CXCL2 / Q000235:genetics / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors*; D015398:Signal Transduction / Q000187:drug effects; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D001565:Benzoates; D054426:Chemokine CXCL2; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D018168:Receptors, Retinoic Acid; D013764:Tetrahydronaphthalenes; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; C061133:tamibarotene; D052247:Nitric Oxide Synthase Type II; D048051:p38 Mitogen-Activated Protein Kinases
keywords: CD14; Chemokine; Lipopolysaccharide; Mitogen-activated protein kinase; Retinoid; Toll-like receptor