This study aimed to investigate the effects and potential mechanism of Polygonati Rhizoma aqueous extract on chronic obstructive pulmonary disease(COPD) in rats. Forty-eight Sprague-Dawley rats were randomly assigned to the normal, model,Yupingfeng Granules(1. 5 g·kg~(-1)), and low-, medium-, and high-dose(0. 25, 0. 5, and 1 g·kg~(-1), respectively) Polygonati Rhizoma aqueous extract groups. The rat model of COPD was established by cigarette smoke inhalation for 8 weeks, and then the modeled rats received corresponding treatment for 4 weeks. The grip strength and fecal moisture content were measured, and the lung index was calculated. Enzyme-linked immunosorbent assay(ELISA) was employed to determine the levels of interleukin(IL)-6 and tumor necrosis factor(TNF)-α in the lung tissue. Hematoxylin-eosin(HE) staining and Masson staining were performed to assess the pathological changes in the lung tissue. Flow cytometry was used to analyze T lymphocytes and their subpopulations in the peripheral blood, and the immunofluorescence assay and Western blot were employed to measure the protein levels of Toll-like receptor 4(TLR4), phosphorylated nuclear factor-kappaB(p-NF-κB), NF-κB, phosphorylated inhibitory kappa B-α(p-IκBα), IκBα, IL-6,and TNF-α in the lung tissue. The results indicated that the treatment with Polygonati Rhizoma aqueous extract significantly reduced the fecal moisture content, enhanced the grip strength, and inhibited inflammatory infiltration and fibrosis in the lung tissue. The treatment increased the Th/Tc ratio and Th cell proportion and decreased the Tc cell proportion in the peripheral blood. Furthermore,the treatment down-regulated the expression levels of TLR4, IL-6, and TNF-α and the p-NF-κB/NF-κB and p-IκBα/IκBα ratios in the lung tissue. In conclusion, Polygonati Rhizoma aqueous extract can ameliorate lung tissue damage in the rat model of COPD by inhibiting the TLR4/NF-κB signaling pathway and the production of inflammatory mediators.
Keywords: Polygonati Rhizoma aqueous extract; TLR4/NF-κB signaling pathway; chronic obstructive pulmonary disease(COPD); inflammation.