IRCCS San Raffaele Scientific Institute, Via Olgettina 60, Milan, Italy.
University of Bordeaux, France.
J Infect. 2020 Aug;81(2):255-259. doi: 10.1016/j.jinf.2020.05.031. Epub 2020 May 21.
In areas of SARS-CoV-2 outbreak worldwide mean air pollutants concentrations vastly exceed the maximum limits. Chronic exposure to air pollutants have been associated with lung ACE-2 over-expression which is known to be the main receptor for SARS-CoV-2. The aim of this study was to analyse the relationship between air pollutants concentration (PM 2.5 and NO2) and COVID-19 outbreak, in terms of transmission, number of patients, severity of presentation and number of deaths.
COVID-19 cases, ICU admissions and mortality rate were correlated with severity of air pollution in the Italian regions.
The highest number of COVID-19 cases were recorded in the most polluted regions with patients presenting with more severe forms of the disease requiring ICU admission. In these regions, mortality was two-fold higher than the other regions.
From the data available we propose a "double-hit hypothesis": chronic exposure to PM 2.5 causes alveolar ACE-2 receptor overexpression. This may increase viral load in patients exposed to pollutants in turn depleting ACE-2 receptors and impairing host defences. High atmospheric NO2 may provide a second hit causing a severe form of SARS-CoV-2 in ACE-2 depleted lungs resulting in a worse outcome.
在全球 SARS-CoV-2 爆发地区，空气中的污染物浓度普遍大幅超过最高限值。慢性暴露于空气污染物与肺部 ACE-2 的过度表达有关，而 ACE-2 已知是 SARS-CoV-2 的主要受体。本研究旨在分析空气中污染物浓度（PM2.5 和 NO2）与 COVID-19 爆发之间的关系，包括传播、患者数量、发病严重程度和死亡人数。
将意大利各地区的空气污染严重程度与 COVID-19 病例、重症监护病房（ICU）入院和死亡率相关联。
COVID-19 病例最多的地区污染最严重，患者的疾病表现更为严重，需要 ICU 入院治疗。在这些地区，死亡率是其他地区的两倍。
根据现有数据，我们提出了一个“双重打击假说”：慢性暴露于 PM2.5 会导致肺泡 ACE-2 受体过度表达。这可能会增加暴露于污染物的患者的病毒载量，进而耗尽 ACE-2 受体并损害宿主防御。大气中高浓度的 NO2 可能会造成第二次打击，导致 ACE-2 耗尽的肺部出现严重的 SARS-CoV-2 感染，从而导致更糟糕的结果。
