title: Epigallocatechin gallate inhibits endothelial exocytosis.
abstract: Consumption of green tea is associated with a decrease in cardiovascular mortality. The beneficial health effects of green tea are attributed in part to polyphenols, organic compounds found in tea that lower blood pressure, reduce body fat, decrease LDL cholesterol, and inhibit inflammation. We hypothesized that epigallocatechin gallate (EGCG), the most abundant polyphenol in tea, inhibits endothelial exocytosis, the initial step in leukocyte trafficking and vascular inflammation. To test this hypothesis, we treated human umbilical-vein endothelial cells with EGCG and other polyphenols, and then measured endothelial exocytosis. We found that EGCG decreases endothelial exocytosis in a concentration-dependent manner, with the effects most prominent after 4 h of treatment. Other catechin polyphenols had no effect on endothelial cells. By inhibiting endothelial exocytosis, EGCG decreases leukocyte adherence to endothelial cells. In searching for the mechanism by which EGCG affects endothelial cells, we found that EGCG increases Akt phosphorylation, eNOS phosphorylation, and nitric oxide (NO) production. NOS inhibition revealed that NO mediates the anti-inflammatory effects of EGCG. Our data suggest that polyphenols can decrease vascular inflammation by increasing the synthesis of NO, which blocks endothelial exocytosis.
authors.affiliation: Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Munekazu
authors.initials: M
authors.lastname: Yamakuchi
authors.forename: Clare
authors.initials: C
authors.lastname: Bao
authors.forename: Marcella
authors.initials: M
authors.lastname: Ferlito
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Lowenstein
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects*; D005089:Exocytosis / Q000187:drug effects*; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism; D020302:Weibel-Palade Bodies / Q000187:drug effects / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D009569:Nitric Oxide; D002392:Catechin; C045651:epigallocatechin gallate; D013917:Thrombin