Prophylactic Catechin-Rich Green Tea Extract Treatment Ameliorates Pathogenic Enterotoxic Escherichia coli-Induced Colitis

Abstract

In this study, we explored the potential beneficial effects of green tea extract (GTE) in a pathogenic <i>Escherichia coli</i> (F18:LT:STa:Stx2e)-induced colitis model. The GTE was standardized with catechin and epigallocatechin-3-gallate content using chromatography analysis. Ten consecutive days of GTE (500 and 1000 mg/kg) oral administration was followed by 3 days of a pathogenic <i>E. coli</i> challenge (1 × 10⁹ CFU/mL). In vitro antibacterial analysis showed that GTE successfully inhibited the growth of pathogenic <i>E. coli</i>, demonstrating over a 3-fold reduction under time- and concentration-dependent conditions. The in vivo antibacterial effect of GTE was confirmed, with an inhibition rate of approximately 90% when compared to that of the <i>E. coli</i> alone group. GTE treatment improved pathogenic <i>E. coli</i>-induced intestinal injury with well-preserved epithelial linings and villi. In addition, the increased expression of annexin A1 in GTE-treated jejunum tissue was detected, which was accompanied by suppressed inflammation-related signal expression, including TNFA, COX-2, and iNOS. Moreover, proliferation-related signals such as PCNA, CD44, and Ki-67 were enhanced in the GTE group compared to those in the <i>E. coli</i> alone group. Taken together, these results indicate that GTE has an antibacterial activity against pathogenic <i>E. coli</i> and ameliorates pathogenic <i>E. coli</i>-induced intestinal damage by modulating inflammation and epithelial cell proliferation.