Single-cell transcriptomic analysis of tumor-infiltrated immune cells from myeloid-specific Usp18 knockout mice

Ubiquitin specific peptidase 18 (USP18) inhibits type I interferon response and mediates ISG15-deconjugation. Here, we examined the role of USP18 in myeloid-linage cells in tumor development. B16F10 melanoma grown in control or myeloid-specific Usp18 knockout mice were analyzed. Single-cell transcriptomic analysis revealed that the profile of tumor-infiltrated immune cells were altered with Usp18 deletion. We observed that increase in M1-polarized macrophages and decrease in myeloid-derived suppressor cells, resulting enhanced anti-tumor microenvironment in Usp18 conditional knockout mice. Overall design: B16F10 melanoma was subcutaneously injected into control (Usp18f/f) or myeloid-specific Usp18 knockout (Usp18f/f LysM-Cre) mice. Tumors were harvested 14 days after tumor injection. Single cell suspension was prepared from harvested tumors. 4 tumors per group were pooled. Live CD45+ cells were sorted on BD FACSAria. Libraries of aproximately 8,000 cells were constructed with 10x Genomics Chromium Single Cell 3' Reagent Kits v3 and sequenced on Illumina HiSeq 4000. Reads were aligned using CellRanger (v3.0.1).