Endocytosis of particulate matter induces cytokine production by neutrophil via Toll-like receptor 4
Endocytosis of particulate matter induces cytokine production by neutrophil via Toll-like receptor 4
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DOI：
10.1016/j.intimp.2018.02.020
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发表时间：
2018-04-01
影响因子：
5.6
通讯作者：
Yoshida, Yasuhiro
中科院分区：
文献类型：
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作者：
Miyak, Tadahiro;Wang, Duo;Yoshida, Yasuhiro
颗粒物(PM)的中位数直径为2.5微米，与呼吸系统和心血管疾病有关。我们以前曾报道过PM在体内的生物学效应，尽管中性粒细胞在启动炎症过程中发挥了重要作用，但很少有报道关注PM吸入与免疫反应之间的关系。在这里，我们研究了PM颗粒大小对中性粒细胞的影响，包括他们的内吞活性和活性氧(ROS)的产生。流式细胞术分析表明，1 PM颗粒很容易被中性粒细胞内吞，内吞作用在4℃时被降低。Dynamin的pleckstrin同源结构域的抑制剂抑制了这一过程；然而，GTP酶和笼蛋白抑制剂不影响内吞作用。与野生型小鼠相比，Toll样受体4(TLR4)基因敲除小鼠和MyD88基因敲除小鼠的中性粒细胞内吞作用明显减少，表明TLR4和MyD88在这一过程中起着重要作用。中性粒细胞介导的内吞作用引起氧化应激，N-乙酰半胱氨酸增强内吞作用。氧化应激标志物，血红素加氧酶-1和p62蛋白的表达水平以内吞依赖的方式增加。吞噬的中性粒细胞产生IL-6和肿瘤坏死因子α，其产生被动力蛋白抑制剂减少。我们观察到CD11b阳性细胞在支气管肺泡灌洗液内吞噬PM。总之，这些结果表明，通过TLR4的内吞作用和ROS的产生对于中性粒细胞启动免疫反应是重要的。
Particulate matter (PM) with a median diameter < 2.5 mu m, is associated with respiratory and cardiovascular diseases. We previously reported the biological effects of PM in vivo, and although neutrophils play an important role in initiating inflammation, few reports have focused on the relationship between PM inhalation and immune responses. Here, we investigated the effect of PM particle size on neutrophils, including their endocytosis activity and reactive oxygen species (ROS) production. Flow cytometry analysis indicated that 1 pm particles are readily endocytosed by neutrophils and that endocytosis is reduced at 4 degrees C. Inhibitors of the pleckstrin homology domain of dynamin repressed this process; however, GTPase and clathrin inhibitors did not affect endocytosis. Endocytosis by neutrophils in Toll-like receptor 4 (TLR4)- and MyD88-knockout mice was reduced compared with that in wild-type mice, indicating that TLR4 and MyD88 are important for the process. Neutrophil-mediated endocytosis caused oxidative stress, and N-acetylcysteine enhanced endocytosis. Expression levels of the oxidative stress markers, heme oxygenase-1 and p62 protein, were increased in an endocytosis-dependent manner. Phagocytosed neutrophils produced IL-6 and TNF alpha, whose production was decreased by dynamin inhibitors. We observed that infiltrated CD11b-positive cells in bronchoalveolar lavage fluid endocytose PMs. Overall, these results indicate that endocytosis and ROS production via TLR4 are important for the initiation of immune responses by neutrophils.