Single-cell RNA sequencing highlights the immunosuppression of IDO1<sup>+</sup> macrophages in the malignant transformation of oral leukoplakia
Yanwen Zhang, Jie Zhang, Simin Zhao, Yan Xu, Yingying Huang, Shaopeng Liu, Peng Su, Caijiao Wang, Yahui Li, Hao Li, Pishan Yang, Chengzhe Yang
Abstract
Rationale: Immunosuppressive tumor microenvironment (iTME) plays an important role in carcinogenesis, and some macrophage subsets are associated with iTME generation.However, the sub-population characterization of macrophages in oral carcinogenesis remains largely unclear.Here, we investigated the immunosuppressive status with focus on function of a macrophage subset that expressed indoleamine 2,3 dioxygenase 1 (Macro-IDO1) in oral carcinogenesis.Methods: We built a single cell transcriptome atlas from 3 patients simultaneously containing oral squamous cell carcinoma (OSCC), precancerous oral leukoplakia (preca-OLK) and paracancerous tissue (PCA).Through single-cell RNA sequencing and further validation using multicolor immunofluorescence staining and the in vitro/in vivo experiments, the immunosuppressive cell profiles were built and the role of a macrophage subset that expressed indoleamine 2,3 dioxygenase 1 (Macro-IDO1) in the malignant transformation of oral leukoplakia was evaluated. Results:The iTME formed at preca-OLK stage, as evidenced by increased exhausted T cells, Tregs and some special subsets of macrophages and fibroblasts.Macro-IDO1 was predominantly enriched in preca-OLK and OSCC, distributed near exhausted T cells and possessed tumor associated macrophage transformation potentials.Functional analysis revealed the established immunosuppressive role of Macro-IDO1 in preca-OLK and OSCC: enriching the immunosuppression related genes; having an established level of immune checkpoint score; exerting strong immunosuppressive interaction with T cells; positively correlating with the CD8-exhausted.The immunosuppression related gene expression of macrophages also increased in preca-OLK/OSCC compared to PCA.The use of the IDO1 inhibitor reduced 4NQO induced oral carcinogenesis in mice.Mechanistically, IFN--JAK-STAT pathway was associated with IDO1 upregulation in OLK and OSCC. Ivyspring