Tumor-Infiltrating Regulatory T-cell Accumulation in the Tumor Microenvironment Is Mediated by IL33/ST2 Signaling
Authors
Jimin Son ; Jae-Won Cho ; Hyo Jin Park ; Jihyun Moon ; Seyeon Park ; Hoyoung Lee ; Jeewon Lee ; Gamin Kim ; Su-Myeong Park ; Sergio A Lira ; Andrew N Mckenzie ; Hye Young Kim ; Cheol Yong Choi ; Yong Taik Lim ; Seong Yong Park ; Hye Ryun Kim ; Su-Hyung Park ; Eui-Cheol Shin ; Insuk Lee ; Sang-Jun Ha
Citation
CANCER IMMUNOLOGY RESEARCH, Vol.8(11) : 1393-1406, 2020-11
Regulatory T cells (Treg) are enriched in the tumor microenvironment (TME) and suppress antitumor immunity; however, the molecular mechanism underlying the accumulation of Tregs in the TME is poorly understood. In various tumor models, tumor-infiltrating Tregs were highly enriched in the TME and had significantly higher expression of immune checkpoint molecules. To characterize tumor-infiltrating Tregs, we performed bulk RNA sequencing (RNA-seq) and found that proliferation-related genes, immune suppression-related genes, and cytokine/chemokine receptor genes were upregulated in tumor-infiltrating Tregs compared with tumor-infiltrating CD4+Foxp3- conventional T cells or splenic Tregs from the same tumor-bearing mice. Single-cell RNA-seq and T-cell receptor sequencing also revealed active proliferation of tumor infiltrating Tregs by clonal expansion. One of these genes, ST2, an IL33 receptor, was identified as a potential factor driving Treg accumulation in the TME. Indeed, IL33-directed ST2 signaling induced the preferential proliferation of tumor-infiltrating Tregs and enhanced tumor progression, whereas genetic deletion of ST2 in Tregs limited their TME accumulation and delayed tumor growth. These data demonstrated the IL33/ST2 axis in Tregs as one of the critical pathways for the preferential accumulation of Tregs in the TME and suggests that the IL33/ST2 axis may be a potential therapeutic target for cancer immunotherapy.