穿山龙总皂苷通过JAK2/STAT3通路对哮喘大鼠肺功能及肺组织炎症和气道重塑的影响

Effects of total saponins of pangolin on lung function, lung tissue inflammation and airway remodeling in asthmatic rats through JAK2/STAT3 pathway

关键词:  哮喘  上皮细胞损伤  穿山龙总皂苷  JAK2/STAT3信号通路

Key words:  asthma  epithelial cell damage  total saponin from rhizoma dioscorea nipponica  JAK2/STAT3 signaling pathway

摘要:

[目的] 探讨穿山龙总皂苷对哮喘大鼠气道上皮细胞损伤的影响及对Janus激酶2（JAK2）/信号转导与转录激活子3（STAT3）信号通路的调节作用。[方法] 采用卵清蛋白诱导建立哮喘大鼠模型，将建模成功的大鼠随机分为模型组、穿山龙总皂苷低剂量组、穿山龙总皂苷中剂量组和穿山龙总皂苷高剂量组，另设正常对照组，支气管插管测定大鼠肺顺应性和肺弹性阻力，酶联免疫吸附法（ELISA）测定肺泡灌洗液中白介素（IL）-4、IL-6和干扰素γ（IFN-γ）水平，苏木精-伊红（HE）染色观察支气管病理损伤，实时荧光定量（qRT-PCR）法检测支气管组织中转化生长因子β1（TGF-β1）和Smad2 mRNA水平，蛋白印迹法检测p-JAK2和p-STAT3蛋白相对表达量。[结果] 正常组大鼠肺组织结构正常完整，无炎性细胞浸润；模型组大鼠肺组织炎症中性粒细胞浸润、间质水肿、肺泡间隔增厚、肺泡内及间质斑片状出血；穿山龙低、中和高剂量组大鼠肺组织病理损伤减轻。与正常对照组比较，模型组大鼠肺顺应性降低，肺弹性阻力、IL-4、IL-6和IFN-γ水平、TGF-β1和Smad2 mRNA水平升高以及p-JAK2/JAK2和p-STAT3/STAT3升高（P<0.05）；与模型组比较，穿山龙总皂苷低、中和高剂量组大鼠肺顺应性升高，肺弹性阻力，IL-4、IL-6和IFN-γ水平，TGF-β1和Smad2 mRNA水平降低以及p-JAK2/JAK2和p-STAT3/STAT3降低（P<0.05），其中各指标以穿山龙总皂苷高剂量组变化最为显著，其次为穿山龙中剂量组和穿山龙低剂量组（P<0.05）。[结论] 穿山龙总皂苷可减轻哮喘大鼠气道上皮细胞损伤，降低炎症反应，改善气道重塑，增强肺顺应性，降低肺弹性阻力，其可能是通过抑制JAK2/STAT3信号通路发挥作用。

Abstract:

[Objective] To investigate the effects of total saponin from rhizoma dioscorea nipponica on airway epithelial cell injury in asthmatic rats and its regulatory effects on Janus kinase 2(JAK2)/signal transducer and activator of transcription 3(STAT3) signaling pathway. [Methods] The asthmatic rat model was established by ovalbumin induction. The rats were randomly divided into model group, total saponin from rhizoma dioscorea nipponica low-dose group, total saponin from rhizoma dioscorea nipponica medium-dose group and total saponin from rhizoma dioscorea nipponica high-dose group, and the normal control group was set up. The levels of interleukin (IL)-4, IL-6 and interferon-γ(IFN-γ) in bronchial lavage fluid were determined by ELISA. The pathological damage of bronchial tissue was observed by HE staining. The mRNA levels of transforming growth factor-β1(TGF-β1) and Smad2 in bronchial tissue were detected by qRT-PCR. The relative expressions of p-JAK2 and p-STAT3 were detected by Western blotting. [Results] The lung tissue structure of rats in normal control group was intact without inflammatory cell infiltration. In the model group, inflammatory neutrophil infiltration, interstitial edema, alveolar septal thickening, patchy hemorrhage in alveolar and interstitial tissues were observed. The pathological injury of lung tissue in low, medium and high dose total saponin from rhizoma tioscorea nipponica groups was alleviated;compared with the normal control group, the lung compliance of the model group, the lung elastic resistance, the levels of IL-4, IL-6 and IFN-γ, the mRNA levels of TGF-β1 and Smad2 were increased, and the relative protein expressions of p-JAK2/JAK2 and p-STAT3/STAT3 were increased (P<0.05). Compared with model group, lung compliance was increased, lung elastic resistance, IL-4, IL-6 and IFN-γ levels, TGF-β1 and Smad2 mRNA levels, and p-JAK2/JAK2 and p-STAT3/STAT3 protein relative expression levels were decreased in total saponin from rhizoma dioscorea nipponica low-dose, medium-dose and high-dose groups (P<0.05). The most significant changes were observed intotal saponin from rhizoma dioscorea nipponica high-dose group, followed by total saponin from rhizoma dioscorea nipponica medium-dose group and total saponin from rhizoma dioscorea nipponica low-dose group (P<0.05). [Conclusion] Total saponin from rhizoma dioscorea nipponica can reduce airway epithelial cell injury, reduce inflammation, improve airway remodeling, enhance lung compliance, and reduce lung elastic resistance in asthmatic rats, which may play a role by inhibiting JAK2/STAT3 signaling pathway.