Fig. 5: Ace2, Tmprss2 and Ctsl expression in mouse in similar cell types, and follows similar patterns with age and smoking.

a, Gradual increase in Ace2 expression by airway epithelial cell type with age. Mean expression of Ace2 in different airway epithelial cells of mice of three consecutive ages. Shown are replicate mice (dots; n = 3 for each age), mean (bar) and error bars (s.e.m.). The effect of mouse age was tested using a two-sided Wald test (P values). TPM, transcripts per million. b, Increase in proportion of Ace2⁺Ctsl⁺ goblet and club cells with age. Percentage of Ace2⁺Ctsl⁺ cells in different airway epithelial cell types of mice of three consecutive ages. The effect of mouse age was tested using a Wald test (P values). c–k, Increase in Ace2 expression in secretory cells with smoking. Mice were exposed daily to cigarette smoke (CS) or filtered air (FA) as control for 2 months after which cells from whole-lung suspensions were analyzed by scRNA-seq (Drop-seq). AM, alveolar macrophages; IM, interstitial macrophages; DC, dendritic cells; LEC, lymphatic endothelial cells; CEC, capillary endothelial cells; EC, endothelial cells; Mono, monocytes. c,d, Uniform manifold approximation and projection analysis of scRNA-seq profiles (dots) colored by experimental group (c) or by Ace2⁺ cells and indicated double-positive cells (d). AT1 and AT2 cells and airway epithelial secretory and ciliated cells are marked by the red dashed line. Macro, macrophage; mono, monocyte. e, Marker genes of AT1, AT2, multicilitated and secretory cell clusters. f, The relative frequency of Ace2⁺ cells is increased by smoking in airway secretory cells but not AT2 cells. Relative proportion of Ace2⁺ and Ace2⁻ cells in smoke-exposed and control mice of different cell types (FA: n = 9 mice; CS: n = 5 mice; error bars represent 95% confidence intervals). g,h, Expression of Ace2 was increased in airway secretory cells (FA: 187 cells; CS: 62 cells), but not in AT2 cells (FA: 3,808; CS: 1,882). Distribution of Ace2 expression in secretory (g) and AT2 (h) cells from control and smoke-exposed mice (P value derived from a Wilcoxon rank-sum test; NS, not significant). i–k, Reanalysis of published bulk mRNA-seq⁶⁹ of lungs exposed to different daily doses of CS show increased expression of Ace2 (i), Tmprss2 (j) and Ctsl (k) after 5 months of chronic exposure; n = 8 mice per condition. Bars show the mean, and error bars show the standard error (**P = 0.0046, ***P = 0.0002 and ****P < 0.0001; one-way ANOVA with Dunnett’s multiple comparisons test, compared to FA group.) l, Expression in placenta. Mean expression (color) and proportion of expressing cells (dot size) of Ace2, Tmprss2 and Ctsl along with marker genes (Supplementary Fig. 14) in single- and double-positive cells from embryonic day (E) 9.5 to E18 of mouse placenta development.