[Effect of fresh Phragmitis Rhizoma on airway inflammation in chronic bronchitis based on TGF-β signaling pathway]

This study aims to explore the mechanism of fresh Phragmitis Rhizoma against chronic bronchitis airway inflammation. The SD rats of SPF grade were divided into control group, model group, Guilongkechuanning group(GLKCN, 1.125 g·kg~(-1)), high-dose fresh Phragmitis Rhizoma group(LG-HD, 15 g·kg~(-1)), and low-dose fresh Phragmitis Rhizoma group(LG-LD, 7.5 g·kg~(-1)). The chronic bronchitis models of rats in other groups except the control group were induced by the modified smoking method. From the 15 th day of modeling, the rats were given corresponding agents by gavage for 20 consecutive days. After the last administration, the rats were sacrificed for sample collection. Enzyme-linked immunosorbent assay(ELISA) was employed to detect serum transforming growth factor-β(TGF-β) and interleukin-6(IL-6) levels. The protein expression of TGF-β, IL-1β and IL-6 in lung tissue was detected by immunohistochemical method. Masson staining was performed to detect collagen fibers and muscle fibers in lung tissue, and HE staining to detect the pathological changes of lung tissue. Human bronchial epithelial(16 HBE) cells were cultured in vitro, and CCK-8(cell counting kit-8) method was used to detect the cytotoxicity of cigarette smoke extract(CSE) and fresh Phragmitis Rhizoma. After the exposure of 16 HBE cells to 3.5% CSE and appropriate concentration(800, 400 μg·mL~(-1)) of fresh Phragmitis Rhizoma for 24 h, quantitative real-time PCR was conducted to determine the mRNA levels of TGF-β and IL-1β, and Western blot was employed to determine the protein levels of TGF-β and IL-6 in the cells. The rat model of chronic bronchitis induced by smoking was successfully established. Fresh Phragmitis Rhizoma reduced serum TGF-β and IL-6 levels, down-regulated the protein levels of TGF-β, IL-1β, and IL-6 in lung tissue, and alleviated pathological changes and fibrotic lesions in lung tissue. Moreover, it down-regulated the CSE-induced protein expression of TGF-β and IL-6 as well as the mRNA level of TGF-β in 16 HBE cells. These results indicated that fresh Phragmitis Rhizoma could prevent airway inflammation from chronic bronchitis and promote cell repair by inhibiting the TGF-β signaling pathway.