Figure 2.

Single cell-RNA sequencing identified high Arg2 expression in CXCR2^Hi myeloid-derived suppressor cell (MDSC). (A) Flowchart of the sample collection from PIS animal at the healthy (CON), local pneumonia (KP1), distant spread (KP2), and ultimate sepsis status (KP3) for sc-RNA sequencing. (B) The two-dimensional UMAP distribution for 881 myeloid cells in PB, with the dominant Arg2 expression in the PB_G2 cluster. (C) The two-dimensional UMAP distribution for 22, 894 myeloid cells in BM, with the dominant Arg2 expression in the BM_G3 cluster. (D) Compared functional scores of Arg2 enriched granulocytes and other granulocytes. (E) Feature plots indicated that Arg2-enriched granulocytes (red circles) belonged to MDSCs, as marked by Itgam (Cd11b) and Ly6g (Gr1). (F) The top 20 genes specially expressed in ARG2 enriched MDSCs (combing PB_G2 and BM_G3) by COSG analysis, including cell surface marker Cxcr2. (G) The heatmap exhibited genes highly expressed in ARG2-enriched MDSCs by FindMarker analysis, with a high abundance of Cxcr2 transcripts. (H) Venn diagram showing the generation of signature genes of the ARG2-enriched MDSCs. (I) Overview of sorting approach of CXCR2^Low and CXCR2^Hi subsets in BM-derived MDSCs. (J) RT-PCR assay validating the high expression of signature genes in the CXCR2^Hi subset from CON mice. (K) The protein level of ARG2 by western blotting and quantitative bar charts. Data were represented as mean ± SD. Statistical significances were analyzed using an unpaired t-test. *p < 0.05, **p < 0.01, ***p < 0.001.