Autophagy plays an essential role in the clearance of Pseudomonas aeruginosa by alveolar macrophages
Autophagy plays an essential role in the clearance of Pseudomonas aeruginosa by alveolar macrophages
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自噬在肺泡巨噬细胞清除铜绿假单胞菌中起着重要作用
DOI：
10.1242/jcs.094573
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发表时间：
2012-01-15
影响因子：
4
通讯作者：
Wu, Min
中科院分区：
文献类型：
--
作者：
Yuan, Kefei;Huang, Canhua;Wu, Min
细胞内细菌已被证明会引起自噬，这会影响感染结果，而细胞外细菌还没有激活自噬的报道。在这里，我们证明了铜绿假单胞菌，一种革兰氏阴性胞外细菌，在肺泡巨噬细胞系(MH-S)和原代肺泡巨噬细胞中都激活了自噬，并显著增加了LC_3点。利用Lc3 Gly120突变体，我们成功地展示了自噬的标志，即Lc3与磷脂酰乙醇胺(PE)的结合。用透射电子显微镜对典型的双膜自噬小体堆积进行了形态观察。此外，PE结合的Lc3的增加确实是由感染而不是抑制溶酶体降解引起的。特异性siRNA分析表明，铜绿假单胞菌通过典型的Beclin-1-ATG7-ATG5途径诱导自噬。雷帕霉素和干扰素-γ(自噬诱导剂)增加了细菌的清除，而Beclin-1和ATG5基因敲除减少了细胞内的细菌。因此，铜绿假单胞菌诱导的自噬代表了一种宿主保护机制，为这种感染的发病机制提供了新的见解。
Intracellular bacteria have been shown to cause autophagy, which impacts infectious outcomes, whereas extracellular bacteria have not been reported to activate autophagy. Here, we demonstrate that Pseudomonas aeruginosa, a Gram-negative extracellular bacterium, activates autophagy with considerably increased LC3 punctation in both an alveolar macrophage cell line (MH-S) and primary alveolar macrophages. Using the LC3 Gly120 mutant, we successfully demonstrated a hallmark of autophagy, conjugation of LC3 to phosphatidylethanolamine (PE). The accumulation of typical autophagosomes with double membranes was identified morphologically by transmission electron microscopy (TEM). Furthermore, the increase of PE-conjugated LC3 was indeed induced by infection rather than inhibition of lysosome degradation. P. aeruginosa induced autophagy through the classical beclin-1–Atg7–Atg5 pathway as determined by specific siRNA analysis. Rapamycin and IFN-γ (autophagy inducers) augmented bacterial clearance, whereas beclin-1 and Atg5 knockdown reduced intracellular bacteria. Thus, P. aeruginosa-induced autophagy represents a host protective mechanism, providing new insight into the pathogenesis of this infection.