BROAD TRANSCRIPTIONAL FIRING REPRESSES BACTERICIDAL ACTIVITY IN HUMAN AIRWAY NEUTROPHILS

Neutrophils are often considered terminally differentiated and poised for bacterial killing. In chronic diseases such as cystic fibrosis (CF), an unexplained paradox pits massive neutrophil presence against prolonged bacteria infections. Here, we show that neutrophils recruited to CF airways in vivo and in an in vitro transmigration model display rapid and broad transcriptional firing, leading to an upregulation of survival and anabolic genes, and a downregulation of antimicrobial genes. Newly transcribed RNAs are mirrored by the appearance of corresponding proteins, confirming active translation in these cells. Remarkably, treatment by the RNA polymerase II and III inhibitor alpha-amanitin restored expression of key antimicrobial genes, and increased bactericidal capacity of CF airway neutrophils in vitro and in short-term sputum cultures ex vivo. Broadly, our findings show that neutrophil plasticity is regulated at the terminal organ via RNA and protein synthesis, leading to adaptations that profoundly impact their canonical functions (i.e., bacterial clearance). Overall design: Using an in vitro model, airway neutrophils were collected after 1, 2, 4 and 6 hour of transmigration towards CFASN

中性粒细胞(Neutrophils)通常被认为是终末分化细胞，且具备执行细菌杀伤的潜能。在囊性纤维化(CF)这类慢性疾病中，存在一个未解的悖论：气道内存在大量中性粒细胞浸润，却伴随持续的细菌感染。本研究显示，体内募集至CF气道的中性粒细胞，以及体外迁移模型中的中性粒细胞，会发生快速且广泛的转录爆发，进而导致生存相关与合成代谢基因的上调、抗菌基因的下调。新转录生成的RNA会对应出现相应蛋白，证实了这类细胞中存在活跃的翻译过程。
值得注意的是，使用RNA聚合酶II和III抑制剂α-鹅膏蕈碱(alpha-amanitin)进行处理后，关键抗菌基因的表达得以恢复，并且在体外以及短期痰液外植体培养中，提升了CF气道中性粒细胞的杀菌能力。
总体而言，我们的研究结果表明，中性粒细胞的可塑性可在终末器官层面通过RNA与蛋白质合成进行调控，由此产生的适应性改变会深刻影响其经典功能（即细菌清除能力）。
实验设计：采用体外模型，收集向CFASN进行迁移1、2、4和6小时后的气道中性粒细胞。