Table1_SARS-CoV-2 infection of endothelial cells, dependent on flow-induced ACE2 expression, drives hypercytokinemia in a vascularized microphysiological system.pdf

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, has caused nearly 7 million deaths worldwide. Severe cases are marked by an aggressive inflammatory response known as hypercytokinemia, contributing to endothelial damage. Although vaccination has reduced hospitalizations, hypercytokinemia persists in breakthrough infections, emphasizing the need for disease models mimicking this response. Using a 3D microphysiological system (MPS), we explored the vascular role in SARS-CoV-2-induced hypercytokinemia.
MethodsThe vascularized micro-organ (VMO) MPS, consisting of human-derived primary endothelial cells (ECs) and stromal cells within an extracellular matrix, was used to model SARS-CoV-2 infection. A non-replicative pseudotyped virus fused to GFP was employed, allowing visualization of viral entry into human ECs under physiologic flow conditions. Expression of ACE2, TMPRSS2, and AGTR1 was analyzed, and the impact of viral infection on ACE2 expression, vascular inflammation, and vascular morphology was assessed.
ResultsThe VMO platform facilitated the study of COVID-19 vasculature infection, revealing that ACE2 expression increased significantly in direct response to shear stress, thereby enhancing susceptibility to infection by pseudotyped SARS-CoV-2. Infected ECs secreted pro-inflammatory cytokines, including IL-6 along with coagulation factors. Cytokines released by infected cells were able to activate downstream, non-infected EC, providing an amplification mechanism for inflammation and coagulopathy.
DiscussionOur findings highlight the crucial role of vasculature in COVID-19 pathogenesis, emphasizing the significance of flow-induced ACE2 expression and subsequent inflammatory responses. The VMO provides a valuable tool for studying SARS-CoV-2 infection dynamics and evaluating potential therapeutics.

背景
引发新型冠状病毒肺炎（COVID-19）的严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）已在全球造成近700万人死亡。重症病例以被称为高细胞因子血症（hypercytokinemia）的剧烈炎症反应为特征，该反应可引发内皮损伤。尽管疫苗接种已降低了住院率，但突破性感染患者仍会出现高细胞因子血症，这凸显了构建能够模拟该炎症反应的疾病模型的必要性。本研究借助3D微生理系统（microphysiological system, MPS），探究了血管在SARS-CoV-2诱导的高细胞因子血症中的作用。
方法
本研究使用由人源原代内皮细胞（endothelial cells, ECs）与基质细胞组成，并包埋于细胞外基质中的血管化微器官（vascularized micro-organ, VMO）MPS，来构建SARS-CoV-2感染模型。本研究采用融合绿色荧光蛋白（GFP）的非复制型假病毒，以实现在生理流条件下可视化观测病毒侵入人源EC的过程。研究分析了ACE2、TMPRSS2与AGTR1的表达情况，并评估了病毒感染对ACE2表达、血管炎症及血管形态的影响。
结果
VMO平台为COVID-19血管感染研究提供了便利，研究发现ACE2的表达会因剪切应力刺激显著上调，从而增强细胞对假型SARS-CoV-2的感染易感性。受感染的EC会分泌包括白细胞介素6（IL-6）在内的促炎细胞因子及凝血因子。受感染细胞释放的细胞因子可激活下游未受感染的EC，为炎症与凝血病提供了放大机制。
讨论
本研究结果凸显了血管在COVID-19发病机制中的关键作用，同时强调了流体力诱导的ACE2表达及后续炎症反应的重要性。VMO平台为研究SARS-CoV-2感染动态及评估潜在治疗手段提供了极具价值的工具。