A growing body of evidence indicates that neutrophil elastase (NE) is involved in the pathogenesis of respiratory infectious diseases, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to analyze the dynamic changes in serum levels of NE associated with inflammation, disease activity, and mortality rate in patients with COVID-19. We measured the serum concentrations of NE, C-Reactive protein (CRP), interleukin (IL)- 4, IL-6, IL-8, IL-10, and vitamin D levels in 83 ICU and 69 non-ICU patients compared with 82 healthy subjects (HS) in three-time points (T1-T3). Serum levels of NE, IL-6, IL-8, and CRP in ICU and non-ICU patients were significantly higher than HS (P < 0.001) in three-time points. Also, serum levels of NE, IL-6, IL-8, and CRP in ICU patients were significantly higher than in non-ICU patients (P < 0.05). On the day of admission (T1), the levels of NE, CRP, IL-6, IL-8 were gradually decreased from T1 to T3. At the same time, IL-4 and IL-10 were gradually increased from T1 to T2 and then reduced to T3. Further analyses demonstrated that the levels of NE, IL-6, and IL-8 in deceased patients were significantly higher than in recovered patients (P < 0.05). The ROC curve analysis demonstrated that markers, including NE, IL-6, and IL-8, were valuable indicators in evaluating the activity of COVID-19. Overall, our results signify the critical role of NE in the pathogenesis of COVID-19, and also, further support that NE has a potential therapeutic target for the attenuation of COVID-19 severity.

越来越多的证据表明，中性粒细胞弹性蛋白酶 (NE) 参与了呼吸道传染病的发病机制，例如严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2)。本研究旨在分析与 COVID-19 患者的炎症、疾病活动和死亡率相关的血清 NE 水平的动态变化。我们测量了 83 名 ICU 和 69 名非 ICU 患者的血清 NE、C-反应蛋白 (CRP)、白细胞介素 (IL)-4、IL-6、IL-8、IL-10 和维生素 D 水平82 名健康受试者 (HS) 在三个时间点 (T1-T3)。ICU和非ICU患者血清NE、IL-6、IL-8、CRP水平均显着高于HS（P < 0.001) 在三个时间点。此外，ICU 患者血清 NE、IL-6、IL-8 和 CRP 水平显着高于非 ICU 患者（P  < 0.05）。入院当日(T1)，NE、CRP、IL-6、IL-8水平从T1至T3逐渐下降。同时，IL-4和IL-10从T1到T2逐渐升高，然后降低到T3。进一步分析表明，死亡患者的 NE、IL-6 和 IL-8 水平显着高于康复患者（P < 0.05)。ROC 曲线分析表明，包括 NE、IL-6 和 IL-8 在内的标记物是评估 COVID-19 活性的有价值指标。总体而言，我们的结果表明 NE 在 COVID-19 的发病机制中的关键作用，并且进一步支持 NE 具有减轻 COVID-19 严重程度的潜在治疗靶点。