Abstract

Endothelial cells (ECs) are an active component of the immune system and interact directly with inflammatory cytokines. While ECs are known to be polarized cells, the potential role of apicobasal polarity in response to inflammatory mediators has been scarcely studied. Acute inflammation is vital in maintaining healthy tissue in response to infection; however, chronic inflammation can lead to the production of systemic inflammatory cytokines and deregulated leukocyte trafficking, even in the absence of a local infection. Elevated levels of cytokines in circulation underlie the pathogenesis of sepsis, the leading cause of intensive care death. Because ECs constitute a key barrier between circulation (luminal interface) and tissue (abluminal interface), we hypothesize that ECs respond differentially to inflammatory challenge originating in the tissue versus circulation as in local and systemic inflammation, respectively. To begin this investigation, we stimulated ECs abluminally and luminally with the inflammatory cytokine tumor necrosis factor alpha (TNF-α) to mimic a key feature of local and systemic inflammation, respectively, in a microvascular mimetic (μSiM-MVM). Polarized IL-8 secretion and polymorphonuclear neutrophil (PMN) transmigration were quantified to characterize the EC response to luminal versus abluminal TNF-α. We observed that ECs uniformly secrete IL-8 in response to abluminal TNF-α and is followed by PMN transmigration. The response to abluminal treatment was coupled with the formation of ICAM-1-rich membrane ruffles on the apical surface of ECs. In contrast, luminally stimulated ECs secreted five times more IL-8 into the luminal compartment than the abluminal compartment and sequestered PMNs on the apical EC surface. Our results identify clear differences in the response of ECs to TNF-α originating from the abluminal versus luminal side of a monolayer for the first time and may provide novel insight into future inflammatory disease intervention strategies.

中文翻译：

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内皮细胞顶基极性协调对微血管模拟物中腔内与非腔外递送 TNF-α 的不同反应

摘要

内皮细胞 (EC) 是免疫系统的活性成分，可直接与炎性细胞因子相互作用。虽然已知 ECs 是极化细胞，但很少研究根底极性对炎症介质反应的潜在作用。急性炎症对于维持健康组织以应对感染至关重要。然而，即使没有局部感染，慢性炎症也会导致全身炎症细胞因子的产生和白细胞运输失调。循环中细胞因子水平升高是脓毒症发病机制的基础，脓毒症是重症监护死亡的主要原因。因为 ECs 构成了循环（管腔界面）和组织（管腔外界面）之间的关键屏障，我们假设 ECs 分别对起源于组织和循环的炎症挑战有不同的反应，如局部和全身炎症。为了开始这项研究，我们在微血管模拟物 (μSiM-MVM) 中分别用炎性细胞因子肿瘤坏死因子 α (TNF-α) 对 ECs 进行了腔外和腔内刺激，以分别模拟局部和全身炎症的关键特征。极化的 IL-8 分泌和多形核中性粒细胞 (PMN) 迁移被量化，以表征 EC 对管腔与非管腔 TNF-α 的反应。我们观察到 ECs 响应 aluminal TNF-α 均匀分泌 IL-8，然后是 PMN 迁移。对 abluminal 处理的反应与在 ECs 的顶端表面形成富含 ICAM-1 的膜褶皱相结合。相比之下，腔内刺激的 EC 分泌到腔内腔室的 IL-8 是腔外腔室的 5 倍，并且在顶端 EC 表面隔离了 PMN。我们的结果首次确定了 ECs 对源自单层的 abluminal 与 luminal 侧的 TNF-α 反应的明显差异，并可能为未来的炎症疾病干预策略提供新的见解。