Epigallocatechin-3-gallate-induced inhibition of interleukin-6 release and adjustment of the regulatory T/T helper 17 cell balance in the treatment of colitis in mice

Epigallocatechin-3-gallate (EGCG) has a promising therapeutic effect for ulcerative colitis (UC), but the treatment mechanism has yet to be fully elucidated. The aim of the present study was to investigate the mechanism of EGCG in the treatment of UC. Experimental colitis mouse models were prepared. The mice were randomly divided into four groups: Normal control, model (MD), 50 mg/kg/day EGCG treatment and 100 mg/kg/day EGCG treatment. The daily disease activity index (DAI) of the mice was recorded, changes in the organizational structure of the colon were observed and the spleen index (SI) was measured. In addition, levels of interleukin (IL)-6, IL-10, IL-17 and transforming growth factor (TGF)-beta 1 in the plasma and hypoxia-inducible factor (HIF)-1 alpha and signal transducer and activator of transcription (STAT) 3 protein expression in colon tissues were evaluated. Compared with the MD group, the mice in the two EGCG treatment groups exhibited decreased DAIs and SIs and an attenuation in the colonic tissue erosion. EGCG could reduce the release of IL-6 and IL-17 and regulate the mouse splenic regulatory T-cell (Treg)/T helper 17 cell (Th17) ratio, while increasing the plasma levels of IL-10 and TGF-beta 1 and decreasing the HIF-1 alpha and STAT3 protein expression in the colon. The experiments confirmed that EGCG treated mice with experimental colitis by inhibiting the release of IL-6 and regulating the body Treg/Th17 balance.