颗粒物对气道上皮TLR2及其下游信号分子表达的影响

 目的  研究颗粒物(particulate matter, PM)暴露所致急性肺损伤的肺组织Toll样受体2 (Toll-like receptors 2, TLR2)及其下游分子的改变。方法  采用气管滴注PM小鼠模型, 将24只SPF级C57BL.6J雄性小鼠随机分成4组(每组6只):对照组、低浓度PM组、中浓度PM组和高浓度PM组。肺泡灌洗液(bronchoalveolar lavage fluid, BALF)细胞分类计数和肺组织苏木精-伊红染色评估肺损伤情况。免疫组化染色法(immunohistochemistry, IHC)观察TLR2在肺脏的表达情况。采用人支气管上皮细胞株BEAS-2B进行体外PM暴露研究, qRT-PCR、Western blot、流式细胞仪检测细胞TLR2及其下游信号分子的表达。结果  各PM暴露组小鼠BALF细胞总数增加, 中性粒细胞数量及构成比增加, 肺组织炎性损伤加重, IHC染色显示TLR2在气道上皮强表达。各PM暴露组支气管上皮细胞TLR2、MyD88 、IRAK1、RelA mRNA水平呈浓度梯度依赖上调表达, TLR2和p-NF-κB蛋白质水平增加。结论  PM所致急性肺损伤中, 肺组织尤其是气道上皮细胞TLR2表达明显上调。TLR2/MyD88/IRAK1/NF-κB信号通路在人支气管上皮细胞的激活可能介导PM所致肺组织的炎性损伤。 

The effect of particulate matter in atmosphere on TLR2 signaling pathway in airway epithelium

Objective  To investigate the expression of Toll-like receptors 2 (TLR2) and its related signaling pathway molecules in the particulate matter (PM)-induced acute lung injury. Methods  By using PM-exposed mice model, twenty-four male SPF C57BL. 6J mice were equally and randomly divided into control group, low-dose PM group, medium-dose PM group and high-dose PM group. Change in pulmonary histopathology was evaluated by cell counts of bronchoalveolar lavage fluid (BALF) and lung haematoxylin-eosin (HE) staining, then the expression of TLR2 was analyzed by immunohistochemistry (IHC). In vitro model, human airway epithelial cells BEAS-2B were exposed to PM, and the qRT-PCR, Western blot, and flow cytometry were utilized to measure the changes of TLR2-related signaling molecules. Results  The lung inflammatory injury of PM-exposed mice was severe. The total cells, the number of neutrophil and neutrophil% in BALF increased. IHC staining showed that the expression of TLR2 in airway epithelium was elevated. In vitro model, PM induced mRNA expression of TLR2, MyD88, IRAK1 and RelA was in dose-dependent manner, and the trend changes of the four genes were consistent. In addition, the protein expression of TLR2 and p-NF-κB in BEAS-2B was high in PM-exposed groups. Conclusions  PM increased the expression of TLR2 in lung, especially in airway epithelial cells. The activation of TLR2/MyD88/IRAK1/RelA/NF-κB signaling pathway might play an important role in the pathogenesis of PM-induced acute lung inflammatory injury.