Chest CT Features from 58 Patients with COVID-19 Pneumonia from the Perspective of ACE2.

BACKGROUND: Chest CT is important for the diagnosis of Corona Virus Disease 2019, which is caused by SARS-CoV-2 via the receptor angiotensin-converting enzyme 2. This study aimed to present special chest CT changes in the detection and management of COVID-19. METHODS: From February 20 to March 6, 2020, clinical data and chest CT of patients with COVID-19 being treated by the Hubei Medical Team were retrospectively analyzed with a time-interval of 2 weeks. In addition, the expressions of ACE2 in different parts of the respiratory system were detected by immunohistochemical staining to explain the special chest CT features of COVID-19 by ACE2 expression. RESULTS: Of 58 patients, the main respiratory manifestations were fever and cough. Spherical or patchy GGO was the initial CT manifestation of COVID-19 pneumonia. CT findings manifested as rapid evolution from focal unilateral to diffuse bilateral ground-glass opacities (GGO) that progressed to or co-existed with consolidations in chest CT scans. Lung consolidation increased as the disease progressed, accounting for 63.2%, 76.3%, and 87.5% in group 1 (disease course with 0 - 2 weeks), group 2 (2 - 4 weeks), and group 3 (> 4 weeks). Fibrous lesions (72.3%), high density vascular shadow (69.2%), reticular pattern (63.1%), and subpleural parallel sign (61.5%) were common signs of chest CT of COVID-19. IHC results showed that ACE2-expression in the pulmonary alveoli was significantly higher than that in the bronchial mucosa and pleura (p < 0.001). CONCLUSIONS: The special change of CT features in the lung of COVID-19 pneumonia patients have a connection with ACE2 expression patterns in the respiratory system.

Effects of Smoking on ACE2 Expression Pattern: Risk and Severity of SARS-CoV-2 Infection.

BACKGROUND: Respiratory epithelium expressing angiotensin-converting enzyme 2 (ACE2) is the entry for novel coronavirus (SARS-CoV-2), pathogen of the COVID-19 pneumonia outbreak, although a few recent studies have found different ACE2 expression in lung tissue of smokers. The effect of smoking on ACE2 expression and COVID-19 is still not clear. So, we did this research to determine the effect of smoking on ACE2 expression pattern and its relationship with the risk and severity of COVID-19. METHODS: The clinical data of COVID-19 patients with smoking and non-smoking were analyzed, and ACE2 expression of respiratory and digestive mucosa epithelia from smoker and non-smoker patients or healthy subjects were detected by immunohistochemical (IHC) staining. RESULTS: Of all 295 laboratory-confirmed COVID-19 patients, only 24 (8.1%) were current smokers with moderate smoking or above, which accounted for 54.2% of severe cases with higher mortality than non-smokers (8.3% vs. 0.4%, p = 0.018). Data analysis showed the proportion of smokers in COVID-19 patients was lower than that in general population of China (Z = 11.65, P < 0.001). IHC staining showed ACE2 expression in respiratory and digestive epithelia of smokers were generally downregulated. CONCLUSIONS: The proportion of smokers in COVID-19 patients was lower, which may be explained by ACE2 downregulation in respiratory mucosa epithelia. However, smoking COVID-19 patients accounted for a higher proportion in severe cases and higher mortality than for non-smoking COVID-19 patients, which needs to be noted.