Activation of STAT3-mediated ciliated cell survival protects against severe infection by respiratory syncytial virus

Respiratory syncytial virus (RSV) selectively targets ciliated cells in human bronchial epithelium and can cause bronchiolitis and pneumonia mostly in infants. To identify molecular targets of intervention during RSV infection in infants, we investigate how age regulates RSV interaction with the bronchial epithelium barrier. Employing precision-cut lung slices and air-liquid interface cultures generated from infant and adult human donors, we found robust RSV virus spread and extensive apoptotic cell death only in infant bronchial epithelium. In contrast, adult bronchial epithelium showed insignificant barrier damage and limited RSV infection. Single nuclear RNA-sequencing revealed age-related insufficiency of an anti-apoptotic STAT3 activation response to RSV infection in infant ciliated cells, which was exploited to facilitate virus spread via the extruded apoptotic ciliated cells carrying RSV. Activation of STAT3 and blockade of apoptosis rendered protection against severe RSV infection in infant bronchial epithelium. Lastly, apoptotic inhibitor treatment of a neonatal mouse model of RSV infection ameliorated infection and inflammation in the lung. Taken together, our findings identify a STAT3-mediated anti-apoptosis pathway as a target to battle severe RSV disease in infants. Overall design: Single nuclei of neonatal and adult air-liquid-interface (ALI) cultures were dissociated and isolated at 1 day post RSV infection and analyzed using single-nuclei RNA sequencing

呼吸道合胞病毒（Respiratory syncytial virus, RSV）可选择性靶向人支气管上皮的纤毛细胞，且主要在婴幼儿群体中引发细支气管炎与肺炎。为明确婴幼儿RSV感染过程中的干预分子靶点，本研究探讨年龄如何调控RSV与支气管上皮屏障的相互作用。本研究采用取自婴幼儿及成人供体的精密切片肺组织与气液界面（air-liquid interface, ALI）培养体系，发现仅在婴幼儿支气管上皮中，RSV可实现高效播散并引发广泛的细胞凋亡。与之相反，成人支气管上皮仅出现轻微的屏障损伤与有限的RSV感染。单核RNA测序（single nuclear RNA-sequencing）结果显示，婴幼儿纤毛细胞中针对RSV感染的抗凋亡STAT3激活反应存在年龄相关的功能缺陷，这一缺陷被病毒利用，通过携带RSV的凋亡纤毛细胞挤出过程促进病毒播散。激活STAT3并阻断细胞凋亡，可对婴幼儿支气管上皮的重症RSV感染起到保护作用。最后，在RSV感染的新生小鼠模型中施以细胞凋亡抑制剂治疗，可减轻肺部感染与炎症反应。综上，本研究证实STAT3介导的抗凋亡通路可作为对抗婴幼儿重症RSV疾病的干预靶点。
实验设计：在RSV感染后1天，对取自新生及成人的气液界面（air-liquid interface, ALI）培养体系的单个细胞核进行解离与分离，随后通过单核RNA测序（single nuclear RNA-sequencing）开展分析。