Single-cell RNA Analysis on ACE2 Expression Provides Insight into SARS-CoV-2 Blood Entry and Heart Injury

Jieyu Guo; Xiangxiang Wei; Qinhan Li; Liliang Li; Zhaohua Yang; Yu Shi; Yue Qin; Xinyue Zhang; Xinhong Wang; Xiuling Zhi; Dan Meng

ACE2 was shown to be present in human lung alveolar epithelial cells 6 . Analysis of single-cell RNA-Seq (scRNA-seq) data in normal human lung tissues demonstrated that ACE2 is mainly expressed in type II alveolar cells (AT2) 7 . The pathological investigation of COVID-19 fatal cases showed exudation and hemorrhage, epithelium injuries, infiltration of macrophages, and fibrosis in the lungs 8 . Pulmonary fibrosis is not only due to that SARS-CoV-2 directly attacking the lung as its target organ, while the activation of cytokine storm in COVID-19 patients also contributes 9, 10 . A retrospective cohort study indicates that patients with chronic obstructive pulmonary disease (COPD) and bilateral pulmonary infiltration are associated with higher mortality 11 . It may be due to the change of ACE2 gene expression profile in lung tissues in patients with lung diseases, which makes these patients more susceptible to SARS-CoV-2 infection, but the cell-type specific expression change of ACE2 in healthy populations and patients with underlying lung diseases has not been reported.