ABSTRACT
BACKGROUND: Angiotensin-converting enzyme 2 (ACE2) has been reported to be the main receptor for SARS-CoV-2 infection of host cells. Understanding the changes in bronchoalveolar epithelial cells after SARS-CoV-2 infection of host cells and the intercellular communication relationship between these epithelial cell changes and immune cells is of great significance for the development of therapeutic methods. METHODS: We explored the single-cell RNA sequence (scRNA-seq) of cells infected with bronchoalveolar lavage fluid (BaLF) of patients with different severities of SARS-CoV-2 and healthy people. RESULTS: We found 11 clusters of epithelial cells in the BaLF, and they were derived from the S group. In the S group, the proportion of cells with positive ACE2 expression was relatively high. ACE2 was relatively more expressed in epithelial cell clusters 1, 3, and 7. Clusters 4 and 5 represented the original state, and there were two differentiation directions: one was cluster 2, and the others were clusters 1, 3, and 6. Cluster 7 was the intermediate state. Clusters 1, 3, 6, and 7 had high similarities (> 0.9), and their main signaling pathways focused on inflammatory activation and immune response. Cluster 2 was relatively specific and was up-regulated in differential genes that were mainly related to apoptosis. The ligand-receptor expression pattern of TNFRSF10D-TNFSF10 showed a special inter-cell regulatory relationship between epithelial cell cluster 2 and macrophages. CONCLUSION: This study revealed the changes in epithelial cells derived from alveolar lavage fluid after SARS-CoV-2 infection and the communication relationship with other immune cells.