Burkholderia cenocepacia-induced delay of acidification and phagolysosomal fusion in cystic fibrosis transmembrane conductance regulator (CFTR)-defective macrophages
Burkholderia cenocepacia-induced delay of acidification and phagolysosomal fusion in cystic fibrosis transmembrane conductance regulator (CFTR)-defective macrophages
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DOI：
10.1099/mic.0.2008/023200-0
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发表时间：
2008-12-01
期刊：
影响因子：
2.8
通讯作者：
Valvano, Miguel A.
中科院分区：
文献类型：
--
作者：
Lamothe, Julie;Valvano, Miguel A.
洋葱伯克霍尔德菌复合体（Bcc）是一组慢性感染囊性纤维化（CF）患者气道的机会性细菌。几个实验室已经证明，Bcc成员，特别是嗜绿芽胞杆菌，在吞噬细胞和上皮细胞内的膜结合液泡中存活。我们之前已经证明，细胞内的cenocepacia会导致吞噬体成熟的延迟，正如酸化受损和晚期吞噬酶体标记物LAMP-1的缓慢积累所揭示的那样。在这项研究中，我们证明未感染的囊性纤维化跨膜传导调节剂（CFTR）缺陷巨噬细胞或用CFTR特异性药物抑制剂治疗的正常巨噬细胞显示正常酸化。然而，与CFTR阳性细胞相比，CFTR阴性的巨噬细胞在摄入新绿芽胞杆菌后，含有细菌的液泡发生酸化和吞噬溶酶体融合的比例较低，这表明CFTR功能的丧失有助于提高细菌的细胞内存活。巨噬细胞暴露于热灭活的芽孢杆菌和感染了非cf病原体（如肠沙门氏菌）的巨噬细胞中，cfr相关的吞噬体成熟缺陷不存在。肠沙门氏菌是一种细胞内病原体，一旦内化，就会迅速转移到获得溶酶体标记的酸性腔室。这些结果表明，转运表型的改变不仅需要有缺陷的CFTR，还需要有活的cenocepacia。我们得出结论，CFTR可能在细胞内感染的清除机制中发挥作用，正如我们之前所表明的那样，定位于溶酶体的cenocepacia细胞失去了细胞包膜的完整性。因此，cftr（-/-）巨噬细胞内含有青绿芽孢杆菌的液泡成熟停滞时间延长可能是CF患者体内细菌持续存在的一个因素。
The Burkholderia cepacia complex (Bcc) is a group of opportunistic bacteria chronically infecting the airways of patients with cystic fibrosis (CF). Several laboratories have shown that Bcc members, in particular B. cenocepacia, survive within a membrane-bound vacuole inside phagocytic and epithelial cells. We have previously demonstrated that intracellular B. cenocepacia causes a delay in phagosomal maturation, as revealed by impaired acidification and slow accumulation of the late phagolysosomal marker LAMP-1. In this study, we demonstrate that uninfected cystic fibrosis transmembrane conductance regulator (CFTR)-defective macrophages or normal macrophages treated with a CFTR-specific drug inhibitor display normal acidification. However, after ingestion of B. cenocepacia, acidification and phagolysosomal fusion of the bacteria-containing vacuoles occur in a lower percentage of CFTR-negative macrophages than CFTR-positive cells, suggesting that loss of CFTR function contributes to enhance bacterial intracellular survival. The CFTR-associated phagosomal maturation defect was absent in macrophages exposed to heat-inactivated B. cenocepacia and macrophages infected with a non-CF pathogen such as Salmonella enterica, an intracellular pathogen that once internalized rapidly traffics to acidic compartments that acquire lysosomal markers. These results suggest that not only a defective CFTR but also viable B. cenocepacia are required for the altered trafficking phenotype. We conclude that CFTR may play a role in the mechanism of clearance of the intracellular infection, as we have shown before that B. cenocepacia cells localized to the lysosome lose cell envelope integrity. Therefore, the prolonged maturation arrest of the vacuoles containing B. cenocepacia within cftr(-/-) macrophages could be a contributing factor in the persistence of the bacteria within CF patients.