Figure 3.  Triangulation of ACE2 expression in the respiratory tract with literature-derived insights.
(A) Schematic representation of the respiratory system highlighting key cell types from the nasal cavity, airway and alveoli. Scatterplot shows comparison of percentage of cells with non-zero expression (x-axis) from eight single-cell studies against literature-derived associations: local score (y-axis and size of circles) and global score (transparency of circles). (B) Assessing literature-based and scRNAseq-based associations between ACE2 and respiratory tract cells. On the left, the dimensionality reduction plots show different cell populations associated with lung and olfactory epithelium. On the right, violin plots show the distribution of ACE2 expression levels in selected populations with non-zero expression. The cell types and the literature-derived local and global associations scores are shown.
Figure 3—figure supplement 1.  ACE2 is strongly correlated to surfactant protein-encoding genes across GTEx lung samples.
Distribution of Pearson correlation coefficients between expression (in TPM) of ACE2 and all other genes detected with a mean of at least 1 TPM in the GTEx lung study (n = 573). The right tail of the distribution (shaded red) includes the top 4% of correlated genes (top). Each gene encoding a known surfactant protein is strongly correlated to ACE2 in lung samples, with the Pearson correlation coefficient among this top 4%.
Figure 3—figure supplement 2.  Negative IHC staining of ACE2 in nasopharynx from Human Protein Atlas.
Shown are two samples from different patients stained with different anti-ACE2 antibodies.