Dendrobium officinale Polysaccharides Protected against CCl4-Induced Liver Fibrosis by Inhibiting Oxidative Stress and TGF-β1 and Wnt/β-Catenin Signaling.

Abstract

Objective: To investigate the potential anti-liver fibrosis (LF) effects of Dendrobium officinale polysaccharides (DOPs) and to further explore the involvement of the antioxidant and anti-inflammatory mechanisms of the transforming growth factor-beta 1 (TGF-β1) and Wnt signaling pathways.

Methods: Seventy male Sprague-Dawley rats were assigned to 5 groups in a randomized block design: control, model, colchicine (COL, 0.1 mg/kg), low-dose DOP (LDD, 0.05 g/kg), and high-dose DOP (HDD, 0.1 g/kg) groups (n=14 per group). LF rat model was induced via subcutaneous injection of carbon tetrachloride (CCl₄). Serum markers of oxidative stress, liver function, and LF were monitored. Pathological examination of liver tissue was performed using hematoxylin and eosin (HE) and Masson's trichrome staining, followed by staging evaluation using the meta-analysis of histological data in viral hepatitis scoring system. Quantitative analysis of the core components of extracellular matrix (ECM) and the regulatory factors [e.g., tissue inhibitor of metalloproteinase-1 (TIMP-1), matrix metalloproteinase-1 (MMP-1)], TGF-β1, and Wnt/β-catenin signaling pathway were performed using real-time quantitative polymerase chain reaction and Western blot, respectively. In addition, the therapeutic effect of DOPs on LF was further evaluated using acoustic radiation force pulses (AFRI) and contrast-enhanced ultrasound (CEUS).

Results: Compared with the model group, HDD dramatically improved liver appearance and index, and alleviated extensive hepatocyte degeneration, interstitial fibrous proliferation, and pseudolobuli formation (P<0.01). Moreover, HDD downregulated mRNA and protein levels of α-smooth muscle actin, type I collagen, and type III collagen in the liver tissue of rats, while maintaining the MMP-1/TIMP-1 ratio by upregulating MMP-1 and downregulating TIMP-1 (P<0.05 or P<0.01). The ARFI and CEUS examination results also confirmed that HDD had significant anti-LF effects. HDD inhibited activation of the TGF-β and Wnt/β-catenin signaling pathways by reducing mRNA and protein levels of TGF-β1, Wnt-1 and β-catenin, while increasing the expression of dickkopf-1 (P<0.05 or P<0.01).

Conclusions: DOPs achieved an anti-LF effect by inhibiting TGF-β1 and Wnt/β-catenin signaling. ARFI and CEUS can be used to evaluate the liver stiffness, microcirculation disorders, and drug efficacy in LF and cirrhosis.