Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan.
Am J Physiol Lung Cell Mol Physiol. 2021 Feb 1;320(2):L193-L204. doi: 10.1152/ajplung.00334.2019. Epub 2020 Oct 28.
Premature infants, especially those with bronchopulmonary dysplasia (BPD), develop recurrent severe respiratory viral illnesses. We have shown that hyperoxic exposure of immature mice, a model of BPD, increases lung IL-12-producing Clec9a CD103 dendritic cells (DCs), pro-inflammatory responses, and airway hyperreactivity following rhinovirus (RV) infection. However, the requirement for CD103 DCs and Clec9a, a DAMP receptor that binds necrotic cell cytoskeletal filamentous actin (F-actin), for RV-induced inflammatory responses has not been demonstrated. To test this, 2-day-old C57BL/6J, CD103 DC-deficient Batf3 or Clec9a mice were exposed to normoxia or hyperoxia for 14 days. Also, selected mice were treated with neutralizing antibody against CD103. Immediately after hyperoxia, the mice were inoculated with RV intranasally. We found that compared with wild-type mice, hyperoxia-exposed Batf3 mice showed reduced levels of IL-12p40, IFN-γ, and TNF-α, fewer IFN-γ-producing CD4 T cells, and decreased airway responsiveness following RV infection. Similar effects were observed in anti-CD103-treated and Clec9a mice. Furthermore, hyperoxia increased airway dead cell number and extracellular F-actin levels. Finally, studies in preterm infants with respiratory distress syndrome showed that tracheal aspirate CLEC9A expression positively correlated with IL12B expression, consistent with the notion that CLEC9A cells are responsible for IL-12 production in humans as well as mice. We conclude that CD103 DCs and Clec9a are required for hyperoxia-induced pro-inflammatory responses to RV infection. In premature infants, Clec9a-mediated activation of CD103 DCs may promote pro-inflammatory responses to viral infection, thereby driving respiratory morbidity.
早产儿,尤其是患有支气管肺发育不良(BPD)的早产儿,会反复发生严重的呼吸道病毒感染。我们已经表明,对不成熟的小鼠(BPD 模型)进行高氧暴露会增加肺部产生白细胞介素-12 的 Clec9a CD103 树突状细胞(DC)、促炎反应和鼻病毒(RV)感染后的气道高反应性。然而,尚未证明 CD103 DC 和 Clec9a(一种结合坏死细胞细胞骨架丝状肌动蛋白(F-actin)的 DAMPs 受体)对 RV 诱导的炎症反应的要求。为了验证这一点,将 2 天大的 C57BL/6J、CD103 DC 缺陷型 Batf3 或 Clec9a 小鼠暴露于常氧或高氧中 14 天。此外,还选择了一些小鼠用针对 CD103 的中和抗体进行治疗。高氧暴露后,立即通过鼻腔接种 RV。我们发现,与野生型小鼠相比,高氧暴露的 Batf3 小鼠在 RV 感染后显示出较低水平的 IL-12p40、IFN-γ 和 TNF-α、较少的 IFN-γ 产生的 CD4 T 细胞和降低的气道反应性。在抗 CD103 处理和 Clec9a 小鼠中也观察到类似的效果。此外,高氧增加了气道死细胞数量和细胞外 F-actin 水平。最后,在患有呼吸窘迫综合征的早产儿中的研究表明,气管吸出物 CLEC9A 表达与 IL12B 表达呈正相关,这表明 CLEC9A 细胞负责人类和小鼠的 IL-12 产生。我们得出结论,CD103 DC 和 Clec9a 是高氧诱导的对 RV 感染的促炎反应所必需的。在早产儿中,Clec9a 介导的 CD103 DC 激活可能会促进对病毒感染的促炎反应,从而导致呼吸发病率增加。