title: Anti-allergic Psidium guajava extracts exert an antitumor effect by inhibition of T regulatory cells and resultant augmentation of Th1 cells.
abstract: Th1 polarization is one of the mechanisms underlying the therapeutic effects of herbal medicine. The action of anti-allergic agents from Psidium guajava (P. guajava) on T cell immunity in mice was investigated. The addition of P. guajava extracts blocked IL-10-mediated, in vitro induction of T regulatory (Tr) cells from CD4+ splenocytes of C57BL/6 mice, whereas the extracts exerted only a weak or no effect on the development of Th1 and Th2 cells. Accordingly, Tr cells were not induced from splenocytes of mice administered orally with the extracts. Furthermore, P. guajava extracts shifted the Th1/Th2 balance to a Th1 dominant status by directly attenuating Tr cell activity. In a study of tumor immunity, mice pretreated with the extracts exhibited retarded growth of s.c. inoculated B16 melanoma cells. These findings suggest that P. guajava extracts are efficacious for the prevention of tumor development by depressing Tr cells and subsequently shifting to Th1 cells.
authors.affiliation: Department of Dermatology, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Hamamatsu, Shizuoka 431-3192, Japan. seo445@hama-med.ac.jp
authors.forename: Naohiro
authors.initials: N
authors.lastname: Seo
authors.forename: Taisuke
authors.initials: T
authors.lastname: Ito
authors.forename: Naili
authors.initials: N
authors.lastname: Wang
authors.forename: Xinsheng
authors.initials: X
authors.lastname: Yao
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Tokura
authors.forename: Fukumi
authors.initials: F
authors.lastname: Furukawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takigawa
authors.forename: Susumu
authors.initials: S
authors.lastname: Kitanaka
mesh_terms: D000818:Animals; D031176:Bidens; D005260:Female; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010936:Plant Extracts / Q000494:pharmacology*; D031647:Psidium; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000276:immunology; D018417:Th1 Cells / Q000187:drug effects* / Q000276:immunology; D018418:Th2 Cells / Q000187:drug effects / Q000276:immunology
chemical_list: D010936:Plant Extracts