Figure 10.

COVID-19 disease induces widespread loss of epithelial cells and compromised polarity, all essential lung function components. Staining for nuclei (DAPI, blue staining), SARS-CoV-2 protein M (SARS-CoV-2-M, green staining), EpCAM (epithelial marker, red staining), and SARS-CoV-2-mRNA (White staining) were performed. 3D reconstructions of lung samples collected from uninfected (control) and COVID-19 (Type 1 or 2, enhanced coagulation and immune infiltration phenotype). In control conditions, EpCAM positive cells underline the alveolar wall as expected (Control). In contrast, in the enhanced coagulation phenotype (COVID-19, type I, damage), a large amount of staining was widely distributed in the lung, but localization was random (COVID-19-type 1). Again, most viral protein M was concentrated inside blood vessels. Also, a population of EpCAM positive cells is positive for viral mRNA (see white arrows). In the immune infiltrating conditions, also we observed significant staining for EpCAM. However, the EpCAM staining was mostly dissociated from the alveolar wall, and groups of epithelial cells can be observed in the alveolar space, even losing their EpCAM polarity, suggesting that cells are probably lost. Thus, the epithelial layer in COVID-19 cases is not functional (n = 13-15 different cases analyzed with a least five sections each).