Original Paper Pharmacology	Planta Med 2006; 72: 697-702 DOI: 10.1055/s-2006-931597
© Georg Thieme Verlag KG Stuttgart · New York
Green Tea Extract Induces Interleukin-8 (IL-8) mRNA and Protein Expression but Specifically Inhibits IL-8 Secretion in Caco-2 Cells
M. I. Netsch1,2, H. Gutmann1, C. Aydogan2, J. Drewe1
1 Department of Research and Clinical Pharmacology, University Hospital, Basel, Switzerland 2 Frutarom Switzerland Ltd., R&D Dept. Phytopharmaceuticals, Waedenswil, Switzerland

Abstract

The chemokine interleukin (IL)-8 is a cytokine involved in neutrophil attraction and activation and elevated levels have been observed in intestinal inflammation. Anti-inflammatory activities have been attributed to green tea or its major constituent (-)-epigallocatechin gallate (EGCG). In this study, we investigated the effects of a defined green tea extract (GTE) or EGCG on basal or IL-1β-induced IL-8 expression and secretion in the human gastrointestinal epithelial cell line Caco-2. mRNA expression levels were determined by quantitative RT-PCR. GTE significantly induced IL-8 mRNA expression, which was not mediated indirectly via an induction of IL-1β mRNA expression. EGCG only exerted a weak although significant induction of IL-8 mRNA expression at the highest concentration. Intracellular and extracellular protein levels were analyzed by an enzyme-linked immunosorbent assay. GTE and EGCG significantly decreased secreted IL-8 concentrations. Determination of intracellular and secreted IL-8 concentrations after 24 h, 48 h, and 72 h of incubation suggested that GTE specifically inhibited IL-8 secretion while inducing de novo synthesis of IL-8. The IL-1β-mediated increase of IL-8 secretion was significantly inhibited by GTE in a dose-dependent manner. At the highest concentration, GTE inhibited IL-1β-induced IL-8 secretion to a similar extent as found for brefeldin A, an inhibitor of vesicular transport. These results suggest that GTE may exert an anti-inflammatory activity in enterocytes, which may be useful for the treatment of intestinal inflammation.

Key words

Green tea - Camellia sinensis (L.) O. Kuntze - Theaceae - chemokines - interleukin-8