Abstract C015: IL-27R signaling modulates protective versus pathogenic T cell responses in hepatocellular carcinoma
Authors: Shi Zhengzheng , Zhu Jiani , Mazitova Aleksandra , Marchenko Anastasiia , Grivennikov Sergei , Koltsova Ekaterina 
Published: November 2024

Abstract
Liver cancer is the 3rd leading cause of cancer death. Hepatocellular carcinoma (HCC) is the major form of primary liver cancer, with a growing incidence rate estimated to surge by 50% in the coming twenty years. Although some success has been achieved with immune checkpoint blockade inhibitors, many HCC patients do not respond well to the treatments. Therefore, it is critical to better understand immune mechanisms regulating HCC to identify new biomarkers and develop novel immunotherapies for HCC patients. HCC is driven by chronic liver diseases and is frequently associated with chronic inflammation in the liver. Cytokines are small mediators of inflammation that play an essential role in inflammatory diseases and tumorigenesis. IL27 is a member of the IL6/IL12 superfamily with context-dependent roles in various inflammatory disorders and cancer. IL27 receptor (R) is expressed by most immune cells and several non-immune cells and plays pivotal roles in the regulation of immune responses. Recent work from our lab shows that IL27R signaling suppresses anti-cancer immune response in HCC, acting via the control of innate cytotoxic cells, and Il27ra -/- mice develop significantly less HCC. However, how IL27R signaling regulates T cell subsets in HCC in vivo remains elusive. Here, using diethylnitrosamine (DEN)-induced mouse model of HCC we found a reduction of regulatory T cells (Tregs) in tumor-bearing Il27ra-/-mice along with lowered HCC burden. ScRNA sequencing of CD45+ cells isolated from HCC tumors indicated a less proliferative phenotype of Tregs and more cytotoxic and less exhausted CD8 T cells in mice with Il27ra deficiency. Pathway analysis suggested that IL27R-deficient Tregs were more quiescent, as characterized by the downregulation of various metabolic pathways. Our newly generated Foxp3 cre Il27ra flox mice show a significant reduction of DEN-driven HCC accompanied by an increase of tumor-infiltrating activated CD8 T cells compared to IL27R sufficient controls. Treg-specific deletion of IL27R caused the upregulation of TCF1 in Tregs which has been recently demonstrated to control Treg immune-suppressive functions in colorectal cancer. Meanwhile, tumor-infiltrating effector CD8 T cells were increased in Foxp3 cre+ Il27ra flox mice relative to their Foxp3 cre- Il27ra flox littermate controls. Interestingly, CD8 T cell specific deletion of IL27R did not impact HCC growth in CD8 cre Il27ra flox mice. Overall, our data suggest that IL27R signaling suppresses anti-HCC immunity by enhancing the pro-tumorigenic Tregs and suppressing anti-tumor effector CD8 T cell functions.
Citation Format: Zhengzheng Shi, Jiani Zhu, Aleksandra Mazitova, Anastasiia Marchenko, Sergei Grivennikov, Ekaterina Koltsova. IL-27R signaling modulates protective versus pathogenic T cell responses in hepatocellular carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C015.