Wu Yu-Qing, Zhou Cheng-Hua, Tao Jin, Li Sheng-Nan
Department of Pharmacology, Nanjing Medical University, Nanjing, PR China.
Life Sci. 2006 May 1;78(23):2689-96. doi: 10.1016/j.lfs.2005.10.029. Epub 2005 Dec 9.
Eosinophils are known to be the important effector cells in asthmatic airway inflammation. The purpose of this study was to investigate the effects of nobiletin, a polymethoxyflavonoid, on eosinophilic airway inflammation of asthmatic rats, and explore its possible mechanisms. Animals were actively sensitized by subcutaneous injection of ovalbumin (OVA). The inflammation in lung tissues of asthmatic rats was observed by hematoxylin and eosin (HE) staining. The eosinophils in blood and BALF were separated by Percoll density gradient centrifugation and counted under microscope. The level of Eotaxin was detected by enzyme-linked immunosorbent assay (ELISA). In addition, the apoptosis of eosinophils was labeled by TdT-mediated dUTP nick end labeling (TUNEL) technique, the semi-quantitative detection for Fas mRNA expression of eosinophils was performed by reverse transcription-polymerase chain reaction (RT-PCR). The airway inflammation of asthmatic rats pretreated with nobiletin was obviously alleviated. Nobiletin (1.5 and 5.0 mg/kg given intraperitoneally) significantly reduced OVA-induced increases in eosinophils, remarkably lowered the level of Eotaxin in blood and broncho-alveolar lavage fluid (BALF) of asthmatic rats. On the other hand, semi-quantitative RT-PCR analysis for Fas of eosinophils from OVA aerosol-challenged sensitized rats showed that Fas mRNA expression of eosinophils was obviously enhanced by nobiletin. Meanwhile, the apoptosis index of cultured eosinophils was significantly elevated after treatment with different doses of nobiletin. These results indicated that nobiletin could inhibit the eosinophilic airway inflammation. Lowering the levels of Eotaxin, relieving airway infiltration of eosinophils and promoting apoptosis of eosinophils by enhancing expression of Fas mRNA may be important mechanisms for nobiletin to antagonize eosinophilic airway inflammation of asthmatic rats.
已知嗜酸性粒细胞是哮喘气道炎症中的重要效应细胞。本研究旨在探讨多甲氧基黄酮诺必亭对哮喘大鼠嗜酸性气道炎症的影响，并探讨其可能的机制。通过皮下注射卵清蛋白（OVA）使动物主动致敏。采用苏木精-伊红（HE）染色观察哮喘大鼠肺组织的炎症情况。通过Percoll密度梯度离心法分离血液和支气管肺泡灌洗液（BALF）中的嗜酸性粒细胞，并在显微镜下计数。采用酶联免疫吸附测定（ELISA）法检测嗜酸性粒细胞趋化因子水平。此外，采用TdT介导的dUTP缺口末端标记（TUNEL）技术标记嗜酸性粒细胞的凋亡，通过逆转录-聚合酶链反应（RT-PCR）对嗜酸性粒细胞Fas mRNA表达进行半定量检测。诺必亭预处理的哮喘大鼠气道炎症明显减轻。诺必亭（腹腔注射1.5和5.0 mg/kg）显著降低OVA诱导的嗜酸性粒细胞增加，显著降低哮喘大鼠血液和支气管肺泡灌洗液（BALF）中嗜酸性粒细胞趋化因子水平。另一方面，对OVA雾化激发致敏大鼠嗜酸性粒细胞Fas的半定量RT-PCR分析表明，诺必亭可明显增强嗜酸性粒细胞Fas mRNA表达。同时，不同剂量诺必亭处理后培养的嗜酸性粒细胞凋亡指数显著升高。这些结果表明，诺必亭可抑制嗜酸性气道炎症。降低嗜酸性粒细胞趋化因子水平、减轻嗜酸性粒细胞气道浸润以及通过增强Fas mRNA表达促进嗜酸性粒细胞凋亡可能是诺必亭拮抗哮喘大鼠嗜酸性气道炎症的重要机制。
