流感的发病率和死亡率与高水平的全身性炎症相关。尽管人类中极少受感染，但内皮细胞在严重甲型流感病毒感染期间发挥了全身性炎症反应的关键作用。内皮细胞如何促进全身性炎症反应还不清楚。在这里，我们开发了一个穿过的系统，其中空气道嗜器官衍生的人类肺上皮细胞与原代人类肺微血管内皮细胞（LMEC）共同培养。我们比较了LMEC对大流行H1N1病毒和近期季节性H1N1和H3N2病毒的易感性，并评估了相关的促炎反应。尽管在LMEC单细胞培养中检测到IAV核蛋白，但没有生产性感染的证据。在上皮细胞-内皮细胞共同培养中，上皮细胞大量感染IAV导致上皮屏障崩溃，但很少检测到LMEC的感染。我们观察到，在IAV感染上皮细胞的LMEC共同培养中，分泌促炎细胞因子的量显著增加，而暴露于IAV的LMEC单细胞培养中则没有。总的来说，我们的数据表明LMEC被IAV流产性感染，但可以推动炎症反应。© 2023 Bauer et al.

Morbidity and mortality from influenza are associated with high levels of systemic inflammation. Endothelial cells play a key role in systemic inflammatory responses during severe influenza A virus (IAV) infections, despite being rarely infected in humans. How endothelial cells contribute to systemic inflammatory responses is unclear. Here, we developed a transwell system in which airway organoid-derived differentiated human lung epithelial cells were co-cultured with primary human lung microvascular endothelial cells (LMECs). We compared the susceptibility of LMECs to pandemic H1N1 virus and recent seasonal H1N1 and H3N2 viruses and assessed the associated pro-inflammatory responses. Despite the detection of IAV nucleoprotein in LMEC mono-cultures, there was no evidence for productive infection. In epithelial-endothelial co-cultures, abundant IAV infection of epithelial cells resulted in the breakdown of the epithelial barrier, but infection of LMECs was rarely detected. We observed a significantly higher secretion of pro-inflammatory cytokines in LMECs when co-cultured with IAV-infected epithelial cells than LMEC mono-cultures exposed to IAV. Taken together, our data show that LMECs are abortively infected by IAV but can fuel the inflammatory response.© 2023 Bauer et al.