Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters
Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters
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DOI：
10.1073/pnas.1508355112
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发表时间：
2015-11-03
影响因子：
11.1
通讯作者：
Rohwer, Forest
中科院分区：
文献类型：
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作者：
Barr, Jeremy J.;Auro, Rita;Rohwer, Forest
噬菌体（Bacteriophage，简称BPHs）保护粘膜表面免受细菌感染。然而，它们与其细菌宿主和粘液覆盖的上皮的复杂相互作用仍然大多未被探索。我们以前的工作表明，T4噬菌体与Hoc蛋白暴露在其衣壳粘附粘蛋白糖蛋白和保护粘液生产的组织培养细胞在体外。在此基础上，我们提出了噬菌体粘附粘液（BAM）免疫模型。在这里，为了测试这个模型，我们开发了一个微流体装置（芯片），模拟粘膜表面经历恒定的流体流动和粘蛋白分泌动力学。在芯片中使用产生粘液的人类细胞和大肠杆菌，我们观察到粘液粘附性T4噬菌体和非粘附性T4 Delta hoc噬菌体在粘液中的相似积累和持久性。然而，与T4 Delta hoc噬菌体相比，T4噬菌体减少上皮的细菌定殖> 4，000倍。这表明噬菌体粘附于粘液通过一些其他机制增加了与细菌宿主的接触。噬菌体传统上被认为是完全依赖于正常的扩散，由随机布朗运动驱动，为主机接触。我们证明，T4噬菌体颗粒在粘液中显示亚扩散运动，而T4 Delta hoc颗粒显示正常扩散。实验和建模表明，当细菌浓度低时，亚扩散运动增加噬菌体-宿主相遇。通过将细菌集中在最佳粘液区，亚扩散增加了它们与宿主的接触和抗菌作用。我们的修正BAM模型提出，粘膜免疫的基本机制是粘附到粘液导致的亚扩散。这些发现表明工程噬菌体操纵和个性化粘膜微生物组的有趣可能性。
Bacteriophages (phages) defend mucosal surfaces against bacterial infections. However, their complex interactions with their bacterial hosts and with the mucus-covered epithelium remain mostly unexplored. Our previous work demonstrated that T4 phage with Hoc proteins exposed on their capsid adhered to mucin glycoproteins and protected mucus-producing tissue culture cells in vitro. On this basis, we proposed our bacteriophage adherence to mucus (BAM) model of immunity. Here, to test this model, we developed a microfluidic device (chip) that emulates a mucosal surface experiencing constant fluid flow and mucin secretion dynamics. Using mucus-producing human cells and Escherichia coli in the chip, we observed similar accumulation and persistence of mucus-adherent T4 phage and nonadherent T4 Delta hoc phage in the mucus. Nevertheless, T4 phage reduced bacterial colonization of the epithelium >4,000-fold compared with T4 Delta hoc phage. This suggests that phage adherence to mucus increases encounters with bacterial hosts by some other mechanism. Phages are traditionally thought to be completely dependent on normal diffusion, driven by random Brownian motion, for host contact. We demonstrated that T4 phage particles displayed subdiffusive motion in mucus, whereas T4 Delta hoc particles displayed normal diffusion. Experiments and modeling indicate that subdiffusive motion increases phage-host encounters when bacterial concentration is low. By concentrating phages in an optimal mucus zone, subdiffusion increases their host encounters and antimicrobial action. Our revised BAM model proposes that the fundamental mechanism of mucosal immunity is subdiffusion resulting from adherence to mucus. These findings suggest intriguing possibilities for engineering phages to manipulate and personalize the mucosal microbiome.