National Heart and Lung Institute, Imperial College London, London, UK.
Mucosal Immunol. 2021 Jul;14(4):815-827. doi: 10.1038/s41385-021-00397-4. Epub 2021 Mar 23.
Viral respiratory infections are a common cause of severe disease, especially in infants, people who are immunocompromised, and in the elderly. Neutrophils, an important innate immune cell, infiltrate the lungs rapidly after an inflammatory insult. The most well-characterized effector mechanisms by which neutrophils contribute to host defense are largely extracellular and the involvement of neutrophils in protection from numerous bacterial and fungal infections is well established. However, the role of neutrophils in responses to viruses, which replicate intracellularly, has been less studied. It remains unclear whether and, by which underlying immunological mechanisms, neutrophils contribute to viral control or confer protection against an intracellular pathogen. Furthermore, neutrophils need to be tightly regulated to avoid bystander damage to host tissues. This is especially relevant in the lung where damage to delicate alveolar structures can compromise gas exchange with life-threatening consequences. It is inherently less clear how neutrophils can contribute to host immunity to viruses without causing immunopathology and/or exacerbating disease severity. In this review, we summarize and discuss the current understanding of how neutrophils in the lung direct immune responses to viruses, control viral replication and spread, and cause pathology during respiratory viral infections.
病毒性呼吸道感染是严重疾病的常见病因，尤其是在婴儿、免疫功能低下者和老年人中。中性粒细胞是一种重要的先天免疫细胞，在炎症损伤后迅速浸润肺部。中性粒细胞有助于宿主防御的最典型的效应机制在很大程度上是细胞外的，并且中性粒细胞在预防多种细菌和真菌感染方面的作用已得到充分证实。然而，中性粒细胞在针对复制于细胞内的病毒的反应中的作用研究较少。目前尚不清楚中性粒细胞是否以及通过哪些潜在的免疫学机制有助于控制病毒或针对细胞内病原体提供保护。此外，需要对中性粒细胞进行严格调控，以避免对宿主组织造成旁观者损伤。在肺部，损伤脆弱的肺泡结构会危及气体交换，导致危及生命的后果，因此这一点尤为重要。在不引起免疫病理学和/或加重疾病严重程度的情况下，中性粒细胞如何有助于宿主对病毒的免疫反应，这在本质上不太清楚。在这篇综述中，我们总结并讨论了目前对肺部中性粒细胞如何指导针对病毒的免疫反应、控制病毒复制和传播以及在呼吸道病毒感染时导致病理学的理解。
