The polysaccharides from Grifola frondosa attenuate CCl4-induced hepatic fibrosis in rats via the TGF-β/Smad signaling pathway

Abstract

The TGF-β1/Smad signaling pathway has been linked to hepatic fibrosis. Previous studies have shown that yellow polysaccharide can prevent the development of hepatic fibrosis. However, it is unclear whether the polysaccharide affects the TGF-β1/Smad signaling pathway. In this experiment, 50 experimental rats were randomly divided into a normal control group, model group, low GFP dose group (50 mg kg^-1), medium GFP dose group (100 mg kg^-1), and high GFP dose group (200 mg kg^-1). A cirrhotic portal hypertension rat model was established by a CCl₄ compound method. After 12 weeks of intragastric administration, the liver index of the medium dose and high dose group was significantly lower than that of the model group. The hepatic fibrosis lesions of rats in each dose group were improved to different extents, and the effect was most significant in the high dose group. The contents of ALT, AST, TBIL and CIV, PCIII, LN and HA in serum were significantly decreased. The activity of SOD and GSH-Px in the liver tissue of GFP medium and high dose groups was significantly increased and the content of MDA was significantly decreased. The contents of TNF-α, IL-1β and IL-6 were significantly decreased. The western blot results showed that the expressions of p-Smad 2/3, Smad4, PAI-1, Imp7 and Imp8 in medium dose and high dose groups were significantly lower than those in the model group, while the expression of Smad7 was significantly higher than that of the model group. The GFP-treated group was able to reduce the expression level of mi R-154 in liver tissue and increase the expression level of miR-146a. GFP has a significant intervention effect on rat hepatic fibrosis, and its mechanism may inhibit the progression of hepatic fibrosis by inhibiting oxidative stress and inflammatory response and regulating TGF-β1/Smad signaling pathway and mi RNA expression.

Fig. 1. The structure sketch of GFP.

Fig. 2. Effect of GFP on HE staining in liver tissues (SP × 400). (A) Control group; (B) model group; (C) GFP 50 mg-treated group; (D) GFP 100 mg-treated group; (E) GFP 200 mg-treated group.

Fig. 3. Effects of GFP on SOD activity (A) GSH-Px activity (B) MDA level (C) in liver tissues of rats with hepatic fibrosis. ^#P < 0.05, ^##P < 0.01 vs. control group, *P < 0.05, **P < 0.01 vs. model group, respectively.

Fig. 4. Effects of GFP on inflammatory factors (A) TNF-α, (B) IL-1β and (C) IL-6 in liver tissue of rats with hepatic fibrosis. ^#P < 0.05, ^##P < 0.01 vs. control group, *P < 0.05, **P < 0.01 vs. model group, respectively.

Fig. 5. (A) Effect of GFP on the protein expression level of p-Smad 2/3 and Smad 2/3 in liver tissue. (B) Effect of GFP on the protein expression level of Smad4,PAI-1and Smad7 in liver tissue. (C) Effect of GFP on the protein expression level of Imp7 and Imp8 in liver tissue. Histogram represents quantification of protein expression levels using ImageJ software. (D) Levels of p-Smad 2/3 and Smad 2/3. (E) Levels of Smad4, PAI-1and Smad7. (F) Levels of Imp7 and Imp8. The expression of protein was analyzed by western bolt. β-Actin was used as an equal loading control. ^#P < 0.05, ^##P < 0.01 vs. control group, *P < 0.05, **P < 0.01 vs. model group, respectively.

Fig. 6. Effects of GFP on miR-154 and miR-146a expression in liver tissues of rats with hepatic fibrosis. (A) Effects of GFP on miR-154 expression in liver tissue. (B) Effects of GFP on miR-146a expression in liver tissue. ^#P < 0.05, ^##P < 0.01 vs. control group, *P < 0.05, **P < 0.01 vs. model group, respectively.