TREM-2 Promotes Macrophage-Mediated Eradication of Pseudomonas aeruginosa via a PI3K/Akt Pathway
TREM-2 Promotes Macrophage-Mediated Eradication of Pseudomonas aeruginosa via a PI3K/Akt Pathway
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TREM-2 通过 PI3K/Akt 途径促进巨噬细胞介导的铜绿假单胞菌根除
DOI：
10.1111/sji.12148
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发表时间：
2014-03-01
影响因子：
3.7
通讯作者：
Wu, M.
中科院分区：
文献类型：
--
作者：
Zhu, M.;Li, D.;Wu, M.
髓系细胞2触发受体（TREM-2）是一种在巨噬细胞和树突状细胞等髓系细胞上大量表达的细胞表面受体。据报道，TREM-2在巨噬细胞和树突状细胞中起炎症抑制剂的作用。然而，TREM-2在细菌杀灭中的作用尚不清楚。本研究探讨了TREM-2在细菌根除铜绿假单胞菌（PA）中的作用，PA是一种引起各种机会性感染的革兰氏阴性细菌。流式细胞术评估的吞噬实验表明TREM-2不参与巨噬细胞对PA的摄取，而细菌平板计数数据显示TREM-2是巨噬细胞介导的PA细胞内杀伤所必需的。此外，我们的研究结果表明，TREM-2通过增强活性氧（ROS）而不是一氧化氮（NO）的产生来促进巨噬细胞的杀伤。用n -乙酰半胱氨酸（一种ROS清除剂）治疗可以减少trem -2介导的PA细胞内杀伤。为了进一步研究trem -2促进细菌杀伤的机制，我们检测了下游丝裂原活化蛋白激酶和PI3K/Akt通路的激活。Western blot数据显示，TREM-2的沉默抑制了Akt的磷酸化，但对ERK、JNK和P38的磷酸化没有抑制作用。此外，PI3K活性产物PIP3 DiC16预处理逆转了trem -2沉默巨噬细胞细胞内细菌负荷的升高，而PI3K抑制剂wortmannin恢复了trem -2过表达巨噬细胞细菌负荷的下降。这些数据共同表明，trem -2介导的细菌杀伤依赖于PI3K/Akt信号的激活，这可能为更好地理解宿主抗菌免疫防御提供了依据。
Triggering receptor expressed on myeloid cells 2 (TREM-2) is a cell surface receptor abundantly expressed on myeloid lineage cells such as macrophages and dendritic cells. It is reported that TREM-2 functions as an inflammatory inhibitor in macrophages and dendritic cells. However, the role of TREM-2 in bacterial killing remains unclear. This study explored the role of TREM-2 in bacterial eradication of Pseudomonas aeruginosa (PA), a Gram-negative bacterium which causes various opportunistic infections. Phagocytosis assay assessed by flow cytometry suggested that TREM-2 was not involved in the uptake of PA by macrophages, while bacterial plate count data showed that TREM-2 was required for macrophage-mediated intracellular killing of PA. Moreover, our results demonstrated that TREM-2 promoted macrophage killing by enhancing reactive oxygen species (ROS), but not nitric oxygen (NO) production. Treatment with N-acetylcysteine, a ROS scavenger, diminished the TREM-2-mediated intracellular killing of PA. To further investigate the underlined mechanisms of TREM-2-promoted bacterial killing, we examined the activation of downstream mitogen-activated protein kinases and PI3K/Akt pathway. Western blot data showed that silencing of TREM-2 inhibited phosphorylation of Akt, but not ERK, JNK or P38. In addition, pretreatment with PI3K active product PIP3 DiC16 reversed the elevation of intracellular bacterial load in TREM-2-silenced macrophages, while PI3K inhibitor wortmannin restored the decline of bacterial load in TREM-2-overexpressed macrophages. These data together suggested that the TREM-2-mediated bacterial killing is dependent on the activation of PI3K/Akt signalling, which may provide a better understanding of the host antibacterial immune defence.