Figure 4.

Intraregional ACE2 and TMPRSS2 mRNA expression in normal human airways

(A) Representative RNA-ISH images demonstrating regional distribution of ACE2 and TMPRSS2 mRNA localization (red signal) in normal human airway surface epithelium. Scale bars, 20 μm.

(B) Comparison of ACE2 and TMPRSS2 mRNA expression between matched nasal and bronchial brushed tissues obtained from seven healthy subjects.

(C) Relative expression of ACE2 and TMPRSS2 mRNA in different airway regions enriched for epithelial cells, including tracheas, bronchi, bronchiole, and alveoli, obtained from matched seven normal lungs.

(D) Frequency of ACE2⁺ and TMPRSS2⁺ cells among total cells identified in distinct anatomical airway regions in a re-analysis of scRNA-seq data (Deprez et al., 2019).

(E) RNA-ISH images depicting mRNA expression of ACE2 and cell type markers, including FOXJ1 (ciliated) (i, ii, and iv), MUC5B (secretory) (iii and v), SFTPC (alveolar type 2) (vi), and HOPX (alveolar type 1 or 2) (vii) on cytospins of nasal versus bronchial superficial epithelial and purified alveolar cells. Scale bars, 10 μm.

(F) Frequency of ACE2⁺ cells among nasal and bronchial preparations. A total of 1,000 cells were analyzed for ACE2 expression per donor (N = 3).

G. Frequency of ACE2⁺ cells among FOXJ1⁺ or MUC5B⁺ cells in nasal or bronchial preparations. A total of 200 FOXJ1⁺ or MUC5B⁺ cells were analyzed for ACE2 expression per donor (N = 3).

(H and I) Histograms depicting number of dot signals of ACE2 expression in FOXJ1 or MUC5B⁺ cells in nasal (H) or bronchial (I) preparations identified by scRNA-ISH. ACE2⁺ dot signals were counted in 200 FOXJ1 or MUC5B⁺ cells per donor (N = 3). Statistics for (B), (C), (F), and (G) used linear mixed-effect model with the donor as random-effect factor for comparison between groups, and pairwise comparisons of groups with more than two levels were performed using Tukey post hoc tests. (H) and (I) used generalized linear mixed-effect models with Poisson distribution to compare the difference in cell counts at varying ACE2 expression amounts between FOXJ1⁺ and MUC5B⁺ cells. Histobars and error bars represent mean ± SD. Different symbol colors indicate results from different individual donors.

See also Figure S3.