title: Antiallergic tea catechin, (-)-epigallocatechin-3-O-(3-O-methyl)-gallate, suppresses FcepsilonRI expression in human basophilic KU812 cells.
abstract: We previously found that the O-methylated derivative of (-)-epigallocatechin-3-O-gallate (EGCg), (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG' '3Me), has potent antiallergic activity. The high-affinity IgE receptor, FcepsilonRI, is found at high levels on basophils and mast cells and plays a key role in a series of acute and chronic human allergic reactions. To understand the mechanism of action for the antiallergic EGCG' '3Me, the effect of EGCG' '3Me on the cell surface expression of FcepsilonRI in human basophilic KU812 cells was examined. Flow cytometric analysis showed that EGCG' '3Me was able to decrease the cell surface expression of FcepsilonRI. Moreover, immunoblot analysis revealed that total cellular expression of the FcepsilonRI alpha chain decreased upon treatment with EGCG' '3Me. FcepsilonRI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. EGCG' '3Me reduced FcepsilonRI alpha and gamma mRNA levels. The cross-linkage of FcepsilonRI causes the activation of basophils, which leads to the secretion of inflammatory mediators including histamine. EGCG' '3Me treatment inhibited the FcepsilonRI cross-linking-induced histamine release. These results suggested that EGCG' '3Me can negatively regulate basophil activation through the suppression of FcepsilonRI expression.
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujimura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tachibana
authors.forename: Mari
authors.initials: M
authors.lastname: Maeda-Yamamoto
authors.forename: Toshio
authors.initials: T
authors.lastname: Miyase
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Sano
authors.forename: Koji
authors.initials: K
authors.lastname: Yamada
mesh_terms: D018926:Anti-Allergic Agents / Q000494:pharmacology*; D001491:Basophils / Q000187:drug effects* / Q000502:physiology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D017455:Receptors, IgE / Q000032:analysis / Q000235:genetics*; D013662:Tea / Q000737:chemistry*
chemical_list: D018926:Anti-Allergic Agents; D012333:RNA, Messenger; D017455:Receptors, IgE; D013662:Tea; C420224:epigallocatechin-3-(3''-O-methyl)gallate; D002392:Catechin