Toxoplasma gondii can infect and replicate in vascular endothelial cells prior to entering host tissues. However, little is known about the molecular interactions at the parasite-endothelial cell interface. We demonstrate that T. gondii infection of primary human umbilical vein endothelial cells (HUVEC) altered cell morphology and dysregulated barrier function, increasing permeability to low-molecular-weight polymers. T. gondii disrupted vascular endothelial cadherin (VE-cadherin) and β-catenin localization to the cell periphery and reduced VE-cadherin protein expression. Notably, T. gondii infection led to reorganization of the host cytoskeleton by reducing filamentous actin (F-actin) stress fiber abundance under static and microfluidic shear stress conditions and by reducing planar cell polarity. RNA sequencing (RNA-Seq) comparing genome-wide transcriptional profiles of infected to uninfected endothelial cells revealed changes in gene expression associated with cell-cell adhesion, extracellular matrix reorganization, and cytokine-mediated signaling. In particular, genes downstream of Hippo signaling and the biomechanical sensor and transcriptional coactivator Yes-associated protein (YAP) were downregulated in infected endothelial cells. Interestingly, T. gondii infection activated Hippo signaling by increasing phosphorylation of LATS1, leading to cytoplasmic retention of YAP, and reducing YAP target gene expression. These findings suggest that T. gondii infection triggers Hippo signaling and YAP nuclear export, leading to an altered transcriptional profile of infected endothelial cells.IMPORTANCE Toxoplasma gondii is a foodborne parasite that infects virtually all warm-blooded animals and can cause severe disease in individuals with compromised or weakened immune systems. During dissemination in its infected hosts, T. gondii breaches endothelial barriers to enter tissues and establish the chronic infections underlying the most severe manifestations of toxoplasmosis. The research presented here examines how T. gondii infection of primary human endothelial cells induces changes in cell morphology, barrier function, gene expression, and mechanotransduction signaling under static conditions and under the physiological conditions of shear stress found in the bloodstream. Understanding the molecular interactions occurring at the interface between endothelial cells and T. gondii may provide insights into processes linked to parasite dissemination and pathogenesis.

中文翻译：

---

弓形虫调节人内皮细胞的屏障功能和机械转导信号。


弓形虫在进入宿主组织之前可以感染血管内皮细胞并在其中复制。然而，人们对寄生虫-内皮细胞界面的分子相互作用知之甚少。我们证明，原代人脐静脉内皮细胞（HUVEC）的弓形虫感染改变了细胞形态和失调的屏障功能，增加了对低分子量聚合物的渗透性。弓形虫破坏血管内皮钙粘蛋白 (VE-cadherin) 和 β-连环蛋白在细胞外周的定位，并减少 VE-钙粘蛋白的表达。值得注意的是，弓形虫感染通过减少静态和微流体剪切应力条件下的丝状肌动蛋白（F-肌动蛋白）应力纤维丰度以及降低平面细胞极性，导致宿主细胞骨架重组。 RNA 测序 (RNA-Seq) 比较了感染内皮细胞和未感染内皮细胞的全基因组转录谱，揭示了与细胞间粘附、细胞外基质重组和细胞因子介导的信号传导相关的基因表达变化。特别是，Hippo 信号下游基因、生物力学传感器和转录共激活因子 Yes 相关蛋白 (YAP) 在受感染的内皮细胞中下调。有趣的是，弓形虫感染通过增加 LATS1 的磷酸化来激活 Hippo 信号传导，导致 YAP 保留在细胞质中，并减少 YAP 靶基因表达。这些发现表明弓形虫感染触发 Hippo 信号传导和 YAP 核输出，导致受感染内皮细胞的转录谱发生改变。重要性 弓形虫是一种食源性寄生虫，几乎可感染所有温血动物，并可在免疫系统受损或减弱的个体中引起严重疾病。在其感染宿主中传播期间，弓形虫突破内皮屏障进入组织并建立慢性感染，导致弓形虫病最严重的表现。本文介绍的研究探讨了原代人内皮细胞的弓形虫感染如何在静态条件下以及在血流中发现的剪切应力的生理条件下诱导细胞形态、屏障功能、基因表达和机械转导信号的变化。了解内皮细胞和弓形虫之间界面处发生的分子相互作用可能有助于了解与寄生虫传播和发病机制相关的过程。