To investigate which cells within human and NHP tissues represent likely SARS-CoV-2 targets, we analyzed new and existing scRNA-seq datasets to assess which cell types express ACE2, alone or with TMPRSS2. In a previously unpublished dataset consisting of NHP (Macaca mulatta) lung tissue collected after necropsy of healthy adult animals and analyzed by using Seq-Well v1 (Gierahn et al., 2017), we recovered at least 17 distinct major cell types, including various lymphoid, myeloid, and stromal populations (Figures 1 A–1C; Table S1; STAR Methods). ACE2 and TMPRSS2 were primarily expressed in epithelial cells, with 6.7% of type II pneumocytes expressing ACE2 and 3.8% co-expressing ACE2 and TMPRSS2 (Figures 1B and 1C). Notably, the only double-positive cells observed were classified within the type II pneumocyte population; however, we also identified TMPRSS2 expression within club cells, ciliated epithelial cells, and type I pneumocytes, albeit at diminished abundance and frequency compared with type II pneumocytes (Figure 1C; Table S1).
Figure 1 Expression of ACE2 in Type II Pneumocytes in Healthy Lungs of Non-human Primates
(A) Schematic of protocol for isolation of lung tissue at necropsy from healthy non-human primates (M. mulatta, n = 3), creation of scRNA-seq libraries by using Seq-Well v1, and computational analysis to identify cell types by using unbiased methods. UMAP projection of 3,793 single cells, points colored by cell identity (see STAR Methods).
(B) Uniform manifold approximation and projection (UMAP) as in (A), points colored by detection of ACE2 (coronavirus receptor, top) or TMPRSS2 (coronavirus S protein priming for entry, bottom). Color coding is as follows: black, RNA positive; blue, RNA negative.
(C) Dot plot of 2 defining genes for each cell type (Table S1) (Bonferroni-adjusted p < 0.001) and ACE2 and TMPRSS2. Dot size represents fraction of cells within that type expressing a given gene, and color intensity represents binned count-based expression amount (log(scaled UMI+1)) among expressing cells. ACE2 is enriched in type II pneumocytes (6.7% expressing, Bonferroni-adjusted p = 8.62E−33), as is TMPRSS2 (29.5% expressing, Bonferroni-adjusted p = 8.73E−153). Of all type II pneumocytes, 3.8% co-express ACE2 and TMPRSS2 (Table S9). Red arrow indicates cell type with largest proportion of ACE2+TMPRSS2+ cells.
(D) Genes differentially expressed among ACE2+ and ACE2− type II pneumocytes. (SCDE package, FDR-adjusted p < 0.05 for IFNGR2, NT5DC1, ARL6IP1, and TRIM27; full results can be found in Table S1).
See also Table S1.