The Relationship of Smoking with ACE2 and COVID-19

Abstract

RATIONALE: Respiratory epithelium expressing angiotensin-converting enzyme 2 (ACE2) is the entry for novel coronavirus, pathogen of the outbreaking pneumonia (COVID-19). 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 COVID-19. Methods: The clinical data of COVID-19 patients with smoking and non-smoking were analysed, and ACE2 expression of respiratory and digestive mucosa epitheliums from smoker and non-smoker patients or healthy subjects were detected by Immunohistochemistry (IHC) staining.Results: only 24 (8.1%) Of 295 laboratory-confirmed COVID-19 patients, were current smokers with moderate smoking or above, which accouted for 54.2% of severe cases with higher motality than non-smokers (8.3% vs 0.4%, p=0.018). Data analysis showed that the proportion of smokers in COVID-19 was lower than that in general population of China (Z=11.65, P<0.001). IHC staining showed downregulated ACE2 expression in respiratory and digestive epitheliums of smokers. Conclusions: The proportion of smokers in COVID-19 patients was lower, which may be explained by ACE2 downregulation in respiratory mucosa epitheliums. However, smoking COVID-19 patients accounted for higher proportion in severe cases and higher motality than non-smoking COVID-19 patients, which need to be noticed.