title: Toll-like receptors as a target of food-derived anti-inflammatory compounds.
abstract: Toll-like receptors (TLRs) play a key role in linking pathogen recognition with the induction of innate immunity. They have been implicated in the pathogenesis of chronic inflammatory diseases, representing potential targets for prevention/treatment. Vegetable-rich diets are associated with the reduced risk of several inflammatory disorders. In the present study, based on an extensive screening of vegetable extracts for TLR-inhibiting activity in HEK293 cells co-expressing TLR with the NF-κB reporter gene, we found cabbage and onion extracts to be the richest sources of a TLR signaling inhibitor. To identify the active substances, we performed activity-guiding separation of the principal inhibitors and identified 3-methylsulfinylpropyl isothiocyanate (iberin) from the cabbage and quercetin and quercetin 4'-O-β-glucoside from the onion, among which iberin showed the most potent inhibitory effect. It was revealed that iberin specifically acted on the dimerization step of TLRs in the TLR signaling pathway. To gain insight into the inhibitory mechanism of TLR dimerization, we developed a novel probe combining an isothiocyanate-reactive group and an alkyne functionality for click chemistry and detected the probe bound to the TLRs in living cells, suggesting that iberin disrupts dimerization of the TLRs via covalent binding. Furthermore, we designed a variety of iberin analogues and found that the inhibition potency was influenced by the oxidation state of the sulfur. Modeling studies of the iberin analogues showed that the oxidation state of sulfur might influence the global shape of the isothiocyanates. These findings establish the TLR dimerization step as a target of food-derived anti-inflammatory compounds.
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shibata
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Fumie
authors.initials: F
authors.lastname: Nakashima
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Honda
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Yu-Jhang
authors.initials: YJ
authors.lastname: Lu
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Research and Development Division, Kagome Company, Limited, 17 Nishitomiyama, Nasushiobara 329-2762, Japan, and.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ushida
authors.affiliation: Research and Development Division, Kagome Company, Limited, 17 Nishitomiyama, Nasushiobara 329-2762, Japan, and.
authors.forename: Koichi
authors.initials: K
authors.lastname: Aizawa
authors.affiliation: Research and Development Division, Kagome Company, Limited, 17 Nishitomiyama, Nasushiobara 329-2762, Japan, and.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suganuma
authors.affiliation: Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Oe
authors.affiliation: Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo 152-8552, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: From the Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan, uchidak@agr.nagoya-u.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005260:Female; D005960:Glucosides / Q000737:chemistry / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D015151:Immunoblotting; D017879:Isothiocyanates / Q000737:chemistry / Q000494:pharmacology; D055666:Lipopeptides / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008807:Mice, Inbred BALB C; D008968:Molecular Conformation; D015394:Molecular Structure; D016328:NF-kappa B / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology; D055503:Protein Multimerization / Q000187:drug effects; D011794:Quercetin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D051193:Toll-Like Receptors / Q000819:agonists / Q000037:antagonists & inhibitors* / Q000737:chemistry; D014675:Vegetables / Q000737:chemistry*
chemical_list: D000893:Anti-Inflammatory Agents; D005960:Glucosides; D017879:Isothiocyanates; D055666:Lipopeptides; D008070:Lipopolysaccharides; D016328:NF-kappa B; C508075:Pam(3)CSK(4) peptide; D010936:Plant Extracts; D051193:Toll-Like Receptors; C110310:quercetin 4'-O-glucopyranoside; C082585:iberin; D011794:Quercetin
keywords: Functional Foods; Inflammation; Isothiocyanate; NF-κB; Pattern Recognition Receptor (PRR); Protein Chemical Modification; Toll-like Receptor (TLR)