Effect of astragaloside Ⅳ on a mouse model of carbon tetrachloride-induced liver fibrosis and its mechanism

ObjectiveTo investigate the liver-protecting and anti-liver fibrosis effects of astragaloside Ⅳ （AS-Ⅳ） in vitro and in vivo， as well as its mechanism of action in intervention against liver fibrosis.MethodsIn the animal experiment， C57BL/6J mice were divided into control group， model group， low-dose AS-Ⅳ （20 mg/kg） group， and high-dose AS-Ⅳ （80 mg/kg） group. The mice were given intraperitoneal injection of carbon tetrachloride for 6 weeks to induce liver fibrosis， and since week 3 of injection， the mice in the low-dose AS-Ⅳ group and the high-dose AS-Ⅳ group were given AS-Ⅳ by gavage at a dose of 20 mg/kg and 80 mg/kg， respectively. The serum levels of alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were measured after 4 weeks of administration， as well as the serum levels of hyaluronic acid （HA）， laminin （LN）， procollagen Ⅲ N-terminal peptide （PⅢNP）， and collagen type Ⅳ （Col-Ⅳ）. HE staining， picrosirius red staining， and Masson staining were used to observe liver histopathology and collagen deposition； RT-qPCR was used to measure the mRNA expression levels of Acta2， Col1a1， and Col3a1 in liver tissue， and Western blot was used to measure the protein expression levels of α-smooth muscle actin （α-SMA）， collagen type Ⅲ （Col-Ⅲ）， phosphatidylinositol 3-kinase （PI3K）， phosphorylated PI3K （pPI3K）， protein kinase B （Akt）， and phosphorylated AKT （p-Akt） in liver tissue； transcriptome sequencing was performed for liver tissue to identify differentially expressed genes and perform a bioinformatics analysis. In the cell experiment， transforming growth factor-β （TGF-β） was used to induce the activation of LX-2 cells， and the PI3K inhibitor LY294002 and the PI3K activator 740 Y-P were used for intervention. The cells were divided into control group， model group， AS-Ⅳ group， LY294002 group， and AS-Ⅳ+740 Y-P group， and the cells were harvested after 36 hours of intervention. Changes in the protein expression levels of α-SMA， Col-Ⅲ， pPI3K/PI3K， and pAkt/Akt in LX-2 cells were measured， as well as changes in the relative mRNA expression levels of Acta2， Col1a1， and Col3a1. A one-way analysis of variance was used for comparison of continuous data between multiple groups， and the least significant difference t-test was used for further comparison between two groups.ResultsIn the animal experiment， compared with the model group， the AS-Ⅳ treatment group had significant reductions in the serum levels of ALT， AST， HA， LN， PⅢNP， and Col-Ⅳ （all P<0.01）， the mRNA expression levels of Acta2， Col1a1， and Col3a1 in liver tissue （all P<0.05）， and the protein expression levels of α-SMA， Col-Ⅲ， pPI3K， and pAkt （Ser473） in liver tissue （all P<0.05）. In the cell experiment， compared with the control group， the model group had significant increases in the protein expression levels of α-SMA， Col-Ⅲ， pPI3K， and pAkt （Ser473） after TGF-β induction （all P<0.05）； compared with the model group， the AS-Ⅳ group had significant reductions in the protein expression levels of α-SMA， Col-Ⅲ， pPI3K， and pAkt （Ser473） （all P<0.05）， and both the AS-Ⅳ group and the LY294002 group had significant reductions in the protein expression level of pPI3K and the relative mRNA expression levels of Acta2， Col1a1， and Col3a1 （all P<0.05）. Compared with the AS-Ⅳ group， there were significant increases in the protein expression level of pPI3K and the relative mRNA expression levels of Acta2， col1a1， and Col3a1 after 740 Y-P intervention （all P<0.05）.ConclusionAS-Ⅳ can inhibit hepatic stellate cell activation and improve liver fibrosis， possibly by inhibiting the PI3K/Akt signaling pathway.