Ingredients of Huangqi decoction slow biliary fibrosis progression by inhibiting the activation of the transforming growth factor-beta signaling pathway

Abstract

Background: Huangqi decoction was first described in Prescriptions of the Bureau of Taiping People's Welfare Pharmacy in Song Dynasty (AD 1078), and it is an effective recipe that is usually used to treat consumptive disease, anorexia, and chronic liver diseases. Transforming growth factor beta 1 (TGFβ1) plays a key role in the progression of liver fibrosis, and Huangqi decoction and its ingredients (IHQD) markedly ameliorated hepatic fibrotic lesions induced by ligation of the common bile duct (BDL). However, the mechanism of IHQD on hepatic fibrotic lesions is not yet clear. The purpose of the present study is to elucidate the roles of TGFβ1 activation, Smad-signaling pathway, and extracellular signal-regulated kinase (ERK) in the pathogenesis of biliary fibrosis progression and the antifibrotic mechanism of IHQD.

Methods: A liver fibrosis model was induced by ligation of the common bile duct (BDL) in rats. Sham-operation was performed in control rats. The BDL rats were randomly divided into two groups: the BDL group and the IHQD group. IHQD was administrated intragastrically for 4 weeks. At the end of the fifth week after BDL, animals were sacrificed for sampling of blood serum and liver tissue. The effect of IHQD on the TGFβ1 signaling pathway was evaluated by western blotting and laser confocal microscopy.

Results: Decreased content of hepatic hydroxyproline and improved liver function and histopathology were observed in IHQD rats. Hepatocytes, cholangiocytes, and myofibroblasts in the cholestatic liver injury released TGFβ1, and activated TGFβ1 receptors can accelerate liver fibrosis. IHQD markedly inhibited the protein expression of TGFβ1, TGFβ1 receptors, Smad3, and p-ERK1/2 expression with no change of Smad7 expression.

Conclusion: IHQD exert significant therapeutic effects on BDL-induced fibrosis in rats through inhibition of the activation of TGFβ1-Smad3 and TGFβ1-ERK1/2 signaling pathways.

Figure 1

HPLC fingerprinting of IHQD. HPLC fingerprinting of Radix Glycyrrhizae (a), Radix Astragali (b), and ingredients of Huangqi decoction (c).

Figure 2

Liver tissue H&E Staining (× 400) and Sirius red staining (× 100). S, sham control group; 1 W-5 W, one to five weeks BDL alone groups; Y, IHQD group.

Figure 3

Changes in TGFβ1, α-SMA, Alb, and CK 7 protein expression detected using confocal microscopy (× 200). S, sham control group; 1 W-5 W, one to five weeks BDL alone groups; Y, IHQD group (a) TGFβ1 (red), α-SMA (green), merge (yellow); (b) TGFβ1 (red), Alb (green), merge (yellow); (c) TGFβ1 (red), CK 7 (green), merge (yellow).

Figure 4

Correlation of positive staining area of TGFβ1 with α-SMA, Alb, and CK 7 protein expression in 1 to 5 weeks BDL alone group. (a) Correlation analysis between TGFβ1 and α-SMA, (b) correlation analysis between TGFβ1 and Alb, (c) correlation analysis between TGFβ1 and CK 7.

Figure 5

Changes in TGFβ1, TβRI, TβRII, Smad3, phospho-Smad3, ERK1/2, phospho-ERK1/2, Smad7, and α-SMA protein expression detected by western blotting. S, sham control group; 1 W-5 W, one to five weeks BDL alone groups; Y, IHQD group.