The anti-fibrotic effects of epigallocatechin-3-gallate in bile duct-ligated cholestatic rats and human hepatic stellate LX-2 cells are mediated by the PI3K/Akt/Smad pathway

Abstract

Aim: (-)-Epigallocatechin-3-gallate (EGCG) is one of the most abundant polyphenols in green tea with strong antioxidant activity and various therapeutic effects. In this study, we investigated the anti-fibrotic effects of EGCG and underlying mechanisms in bile ductligated (BDL) rats and a liver fibrosis model in vitro. Methods: BDL rats were treated with EGCG (25 mg·kg -1 ·d -1, po) for 14 d, and then the serum, bile and liver samples were collected. Liver fibrosis was assessed by serum, urine and bile biochemistry analyses and morphological studies of liver tissues. TGF-β1-stimulated human hepatic stellate LX-2 cells were used as a liver fibrosis model in vitro. The expression of liver fibrogenic genes and signaling proteins in the PI3K/Akt/Smad pathway was examined using Western blotting and/or real-time PCR. Results: In BDL rats, EGCG treatment significantly ameliorates liver necrosis, inflammation and fibrosis, and suppressed expression of the genes associated with liver inflammation and fibrogenesis, including TNF-α, IL-1β, TGF-β1, MMP-9, α-SMA, and COL1A1. In LX-2 cells, application of EGCG (10, 25 µmol/L) dose-dependently suppressed TGF-β1-stimulated expression of COL1A1, MMP-2, MMP-9, TGF-β1, TIMP1, and α-SMA. Furthermore, EGCG significantly suppressed the phosphorylation of Smad2/3 and Akt in the livers of BDL rats and in TGF-β1-stimulated LX-2 cells. Application of LY294002, a specific inhibitor of PI3K, produced similar effects as EGCG did in TGF-β1-stimulated LX-2 cells, but co-application of EGCG and LY294002 did not produce additive effects. Conclusion: EGCG exerts anti-fibrotic effects in BDL rats and TGF-β1-stimulated LX-2 cells in vitro via inhibiting the PI3K/Akt/Smad pathway.

Molecular Mechanism of Pancreatic Stellate Cells Activation in Chronic Pancreatitis and Pancreatic Cancer

“…However, recently, Cui et al have found that activating the PI3K/Akt/mTOR pathway could inhibit autophagy and further suppress PSCs activation [125][126][127]. They also suggested that TGF-β1 might be regulated by PI3K/Akt pathway, but the significance of this crosstalk still required further study [128][129][130].…”

Unconjugated bilirubin elevation impairs the function and expression of breast cancer resistance protein (BCRP) at the blood-brain barrier in bile duct-ligated rats

“…The brain tissues were obtained for substrate analysis, Western blot analysis and biochemical parameter measurements. The levels of bilirubin, bile acids, serum albumin and activities of ALT, AST and ALP in serum and levels of MDA, SOD, ATP and NO in brain were determined with commercial reagent kits according to the manufacturer's instruc tions [15,36,37] . Livers and spleens were also isolated and weighed.…”

The anti‐hepatic fibrosis effects of dihydrotanshinone I are mediated by disrupting the yes‐associated protein and transcriptional enhancer factor D2 complex and stimulating autophagy

“…Traditional Chinese medicine is a valuable part of Chinese culture, and monomeric compounds from Chinese herbs are potential therapeutics for liver fibrosis. In previous studies, we reported that (–)‐Epigallocatechin‐3‐gallate (EGCG) (Yu et al , ), gastrodin (Zhao et al , ) and bicyclol (Zhen et al , ) had protective a effect on liver fibrosis, but their mechanisms were not fully elucidated. Here, we report that DHI, the lipophilic component of S. miltiorrhiza Bunge, shows excellent anti‐fibrotic efficacy.…”

“…The GAPDH/Gapdh gene was used as an internal reference to normalize target gene expressions. Fold changes in the mRNA levels of target genes related to the invariant control were calculated as described previously (Yu et al , ).…”