A polysaccharide from Codonopsis pilosula roots attenuates carbon tetrachloride-induced liver fibrosis via modulation of TLR4/NF-κB and TGF-β1/Smad3 signaling pathway

The present work reported the extraction, purification, characterization of a polysaccharide from roots of Codonopsis pilosula (CPP-A-1) and its effect on liver fibrosis. The findings exhibited that the molecular weight of CPP-A-1 was 9424 Da, and monosaccharide composition were glucose and fructose and minor contents of arabinose. Structural characterization of CPP-A-1 has a backbone consisting of→(2-β-D-Fruf-1)n→ (n ≈ 46-47). Treatment with CPP-A-1 inhibited the proliferation of transforming growth factor-beta 1 (TGF-β)-activated human hepatic stellate cell line (LX-2), and induced cell apoptosis. We used carbon tetrachloride (CCl₄) to construct mice model of liver fibrosis and subsequently administered CPP-A-1 treatment. The results showed that CPP-A-1 alleviated CCl₄-induced liver fibrosis as demonstrated by reversing liver histological changes, decreased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) contents, collagen deposition, and downregulated fibrosis-related collagen I and α-smooth muscle actin (α-SMA), and inhibited the generation of excessive extracellular matrix (ECM) components by restoring the balance between matrix metalloproteinases (MMPs) and its inhibitor (TIMPs). Moreover, CPP-A-1 improved anti-oxidation effects detected by promoting liver superoxide dismutase (SOD), glutathione (GSH) and Mn-SOD levels, and inhibition of liver malondialdehyde (MDA) and iNOS levels. CPP-A-1 also ameliorated the inflammatory factor (tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6), and expression of inflammatory factor genes (TNF-α, IL-11 mRNA). In addition, our results showed that CPP-A-1 inhibited Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) and transforming growth factor-β1 (TGF-β1)/drosophila mothers against decapentaplegic 3 (Smad3) signaling pathways. Furthermore, In vitro tests of LX-2 cells demonstrated that CPP-A-1 not only inhibited α-SMA expression with lipopolysaccharide (LPS) or TGF-β1 stimulation, but also inhibited TLR4/NF-κB and TGF-β1/Smad3 signaling, similar to corresponding small-molecule inhibitors. Therefore, CPP-A-1 might exert suppressive effects against liver fibrosis by regulating TLR4/NF-κB and TGF-β1/Smad3 signaling, our findings support a possible application of CPP-A-1 for the treatment of liver fibrosis.