title: Epigallocatechin gallate induces apoptosis of monocytes.
abstract: BACKGROUND
  Monocytes are the main effector cells of the immune system, and the regulation of their survival and apoptosis is essential for monocyte-involved immune responses. Green tea polyphenol catechin has been reported to have antiallergic and anti-inflammatory activities, but its effect on monocytes has not yet been explored.
  
  
  OBJECTIVE
  To elucidate the mechanisms of the anti-inflammatory effect of catechin, we studied the effect of catechin, especially epigallocatechin gallate (EGCG), on the apoptosis of monocytes.
  
  
  METHODS
  Isolated peripheral blood monocytes were incubated without or with catechin, and apoptosis was evaluated by annexin V and propidium iodide double-staining or terminal deoxynucleotidyl assay. The activation of caspases 3, 8, and 9 was also evaluated by flow cytometry. The influence of GM-CSF or LPS, the known monocyte survival factors, on the EGCG-induced apoptosis of monocytes was investigated.
  
  
  RESULTS
  Among the 4 catechin derivatives tested, EGCG and epicatechin gallate induced apoptosis of monocytes. Caspases 3, 8, and 9, which play a central role in the apoptotic cascade, were dose-dependently activated by EGCG treatment. The EGCG-induced apoptosis of monocytes was not affected by GM-CSF or LPS.
  
  
  CONCLUSIONS
  Catechin, especially EGCG, by promoting monocytic apoptosis, may be a new promising anti-inflammatory agent, and should be tested in clinical trials.
authors.affiliation: Department of Surgical Oncology, Faculty of Medicine, University of Tokyo, Japan. kz-kawai@mvd.biglobe.ne.jp
authors.forename: Kazushige
authors.initials: K
authors.lastname: Kawai
authors.forename: Nelson H
authors.initials: NH
authors.lastname: Tsuno
authors.forename: Joji
authors.initials: J
authors.lastname: Kitayama
authors.forename: Yurai
authors.initials: Y
authors.lastname: Okaji
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yazawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Asakage
authors.forename: Shin
authors.initials: S
authors.lastname: Sasaki
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
authors.forename: Koki
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nagawa
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D013662:Tea
chemical_list: D000893:Anti-Inflammatory Agents; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D020169:Caspases