title: Inhibitory effect of catechin against the superantigen staphylococcal enterotoxin B (SEB).
abstract: Staphylococcal superantigens (SsAgs) have gained attention as one of the factors aggravating atopic dermatitis (AD) and several potential mechanisms of AD aggravation by SsAgs have been reported. Tea catechin has been found to have many unique antimicrobiological activities such as antibacterial, antiviral, antifungal and antitoxic effects. In the present study, we investigated the inhibitory effect of the green tea catechin extract, Polyphenon, and (-)-epigallocatechin gallate (EGCg) on staphylococcal enterotoxin B (SEB) and its mechanisms of action, and we also discuss the possibility of therapeutic benefits for AD patients of tea catechin. Polyphenon inhibited the lethal toxicity of SEB and the SEB-induced production of TNF-alpha, IFN-gamma and IL-4 following its intraperitoneal administration to BALB/c mice. Although Polyphenon is composed of several isomers among which EGCg is approximately 50% of the total, we considered that most of the inhibitory effect of Polyphenon in mice could be attributed to EGCg. EGCg was immediately bound to SEB molecules and neutralized SEB in a dose- and incubation time-dependent manner without molecular weight alteration of the SEB molecule. Furthermore, EGCg inhibited SEB-induced TNF-alpha and IFN- gamma production and IL-2, IFN-gamma, IL-10 and IL-12 p40 mRNA expression in human PBMCs from normal donors in a dose-dependent manner. Inhibition of SsAg-induced T-cell activation by catechin was observed in both in vivo and in vitro studies, suggesting that catechin may be useful in the treatment of AD.
authors.affiliation: Department of Microbiology and Immunology, Showa University School of Medicine, 1-5-8, Hatanodai, Shinagawa-ku, 142-8555 Tokyo, Japan. han65670@rio.odn.ne.jp
authors.forename: Michi
authors.initials: M
authors.lastname: Hisano
authors.forename: Koushi
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yuusuke
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Masafumi
authors.initials: M
authors.lastname: Iijima
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Adachi
authors.forename: Tadakatsu
authors.initials: T
authors.lastname: Shimamura
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D015153:Blotting, Western; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D016207:Cytokines / Q000097:blood / Q000235:genetics; D003876:Dermatitis, Atopic / Q000188:drug therapy* / Q000276:immunology; D004305:Dose-Response Relationship, Drug; D004768:Enterotoxins / Q000633:toxicity*; D005260:Female; D005688:Galactosamine / Q000276:immunology / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000032:analysis; D018089:Superantigens / Q000633:toxicity*; D013662:Tea
chemical_list: D000975:Antioxidants; D016207:Cytokines; D004768:Enterotoxins; D012333:RNA, Messenger; D018089:Superantigens; D013662:Tea; C031818:enterotoxin B, staphylococcal; D005688:Galactosamine; D002392:Catechin; C045651:epigallocatechin gallate; C472086:polyphenon E