Preoperative exercise therapy attenuates the progression of liver metastases following surgical stress by inducing Kupffer cells-mediated anti-tumor trained immunity

Abstract Introduction: Colorectal cancer (CRC) is a devastating disease, causing mortality worldwide, with the majority of the patients dying from hepatic metastasis. Resection of hepatic metastases improves overall disease-free survival. Unfortunately, not all patients have a successful surgical outcome. Pre-operative exercise therapy (PEx) have been demonstrated to be beneficial in the prevention of post-operative complications. Trained immunity in myeloid cells leads to an aggravated long-term inflammatory phenotype upon a secondary stimulation, a process that results from orchestrated metabolic-epigenetic changes. We hypothesize that PEx initially reverts pro-tumorigenic inflammatory responses following surgical stress and maintains an anti-tumor immune microenvironment through modulating Kupffer cells (KCs) with anti-tumor immunity. Methods: 8-week C57BL/6 mice were randomly divided into PEx and sedentary (Sed) groups, mice with PEx run on a motorized treadmill at a speed of 12.5 m/min for 60 min/day, 5 days/week for 4 weeks. 105 MC38 cells were injected directly through portal vein and surgical stress was subjected to a model of partial hepatic ischemia and reperfusion. The tumor progression was determined by bioluminescent imaging weekly. Both hepatic and tumor CD45+ cells from PEx or Sed mice 3 weeks after IR were submitted for single-cell RNA sequencing (scRNA-seq). Results: 4 weeks of PEx significantly reduces metastasis in the liver along 3 weeks after IR, compared with Sed controls. For the scRNA-seq, 11 cell lineages (KCs, monocytes, neutrophils, DCs, TAMs, TANs, B cells, CD4+ T cells, CD8+ T cells, NK cells, and NKT cells) were identified and annotated according to the transcriptomic profile of feature genes expression. Surprisingly, discontinued 4-week-PEx still led to a significant transcriptomic shift in the KCs. 3 clusters from the entire KCs population were unique in PEx mice. In contrast, 2 Clusters were derived from Sed mice. PEx-relevant KCs are enriched in gene expression related to the anti-tumor phenotype, whereas Sed-relevant KCs are enriched in gene expression related to pro-tumor or immunosuppressive phenotype, which suggests that PEx modulates transcriptomic changes in KCs towards an anti-tumor phenotype. Furthermore, with our established ex vivo trained immunity assay, we observe a clear induction of trained immunity in PEx-KCs when co-cultured with MC38 tumor cells, with noticeably higher levels of anti-tumor cytokines interferon (IFN)-γ and TNF-α compared to Sed-KCs. Summary: Our study is one of the first to show that PEx alters the hepatic immune microenvironment by shifting KC to a tumoricidal phenotype. This work offers a rationale for PEx for cancer patients undergoing liver surgery thereby decreasing post-operative metastases and morbidity. Citation Format: Hongji Zhang, Xiang Cheng, Chengli Shen, Meihong Deng, Allan Tsung, Hai Huang. Preoperative exercise therapy attenuates the progression of liver metastases following surgical stress by inducing Kupffer cells-mediated anti-tumor trained immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2109.