Tunneling Nanotubes (TNTs): An Export/Import Strategy for Chlamydia via direct Cell-to-Cell Communication

衣原体是专性细胞内细菌，可引起性传播疾病、眼部感染和非典型肺炎。这些细菌在非酸化的膜结合包涵体中经历独特的双相发育周期。衣原体利用宿主细胞运输机制来调节其生存、生理维持和从感染细胞输出。隧道纳米管（TNTs）是促进细胞间运输、通信和其他生理和病理功能的细胞连接。在最近的一项研究中，我们发现感染沙眼衣原体的宿主细胞使用tnt将细菌（作为网状体，RBs）输出到未感染的邻近细胞中，这表明这些管道在衣原体的直接细胞间传播中起着关键作用。这种转移需要一个功能性的细胞骨架，即使在细胞外传播受损时也会发生。参与衣原体转移的tnt以微管和衣原体snare样效应蛋白IncA为特征。虽然我们的研究为tnt介导的衣原体从感染细胞向非感染细胞的输出提供了重要的见解，但更详细地了解这种新发现的出口/进入策略至关重要。我们的目标是揭示衣原体生物发生和获取/使用tnt的分子和细胞过程。我们将采用最先进的细胞和分子生物学方法来功能表征衣原体如何滥用和操纵TNT形成在邻近细胞之间传播感染。此外，我们将鉴定参与这种相互作用的细胞宿主和病原体来源的蛋白质，探索氧化应激和应激受体对TNT形成和稳定性的影响，并评估衣原体IncA蛋白在TNT介导的转移中的作用。我们的工作也将集中在衣原体在缺氧和抗生素治疗引起的持续细胞感染下的TNT传播问题，其中IncA的表达和功能是维持的。我们的研究旨在了解衣原体如何利用细胞间通讯机制通过细胞间接触直接输出感染。

Chlamydiae are obligate intracellular bacteria that can cause sexually transmitted diseases, ocular infections, and atypical pneumonia. These bacteria undergo a unique biphasic developmental cycle within a non-acidified membrane-bound inclusion. Chlamydiae exploit the host cell transport machinery to regulate their survival, physiological maintenance, and export from infected cells. Tunneling nanotubes (TNTs) are cellular connections that facilitate cell-to-cell transport, communication, and other physiological and pathological functions. In a recent study, we discovered that Chlamydia trachomatis-infected host cells use TNTs to export bacteria (as reticulate bodies, RBs) into uninfected neighboring cells, suggesting that these conduits play a critical role in direct cell-to-cell transmission of chlamydia. This transfer requires a functional cytoskeleton and occurs even when extracellular dissemination is impaired. The TNTs involved in the chlamydial transfer are characterized by microtubules and the chlamydial SNARE-like effector protein IncA. Although our studies provide an important insight into the TNT-mediated export of chlamydia from infected to non-infected cells, a more detailed understanding of this newly discovered exit/entry strategy is crucial. We aim to unravel the molecular and cellular processes involved in the biogenesis and acquisition/use of TNTs by Chlamydia. We will employ state-of-the-art cell and molecular biological methods to functionally characterize how chlamydia misuses and manipulates TNT formation to spread infection between neighboring cells. Additionally, we will identify cellular host and pathogen-derived proteins involved in this interaction, explore the impact of oxidative stress and stress adaptors on TNT formation and stability, and assess the involvement of chlamydial IncA protein in TNT-mediated transfer. Our work will also focus on the issues of chlamydial TNT transmission under hypoxia and in persistent cell infections induced by antibiotic treatment, where the expression and function of IncA are maintained. Our studies aim to understand how chlamydiae use intercellular communication mechanisms to export infections directly through cell-to-cell contact.