Abstract C001: Cytomegalovirus infection modulates distinct immune cell dynamics across tumor-immune microenvironments and systemic macroenvironment during metastasis
Authors: Dong Wenjuan , Sheng Jianting , Xu Shan , Vasquez Matthew , Zhao Hong , Wong Stephen T.C 
Published: November 2024

Abstract
Cytomegalovirus (CMV) is ubiquitously present worldwide and has been implicated in the modulation of cancer development and spread. Notably, CMV proteins have been detected in approximately 90% of lymph node and brain metastases in breast cancer, suggesting its potential influencing tumor invasiveness and metastases. This study investigates the effects of CMV infection on the tumor microenvironment and macroenvironment during metastatic progression in triple-negative breast cancer (TNBC). We employed a syngeneic TNBC mouse model designed to develop spontaneous metastases following primary tumor resection. Using multi-omics sequencing and comprehensive analysis tools, we characterized the tumor-immune landscape across multiple organs relevant to CMV infection and tumor metastasis, including blood, bone marrow, spleen, lungs, brain, and lymph nodes. Our results demonstrate that CMV infection systematically activated the immune response, suppressing primary tumor growth and subsequent metastasis. At the primary tumor site, prior to metastasis, CMV-infected mice exhibited significantly lower proportions of macrophages and plasma cells compared to uninfected counterparts, while CD8+ T cells were significantly enriched. In contrast, the proportions of neutrophils and dendritic cells did not significantly differ between the groups. Distinct patterns of immune cell dynamics were observed at metastatic sites. In the spleen of CMV-infected mice, a notable reduction in macrophages and elevated neutrophil levels were detected. Lung tissues displayed a marked increase in macrophages, CD8+ T cells, and dendritic cells in CMV-infected mice. Interestingly, in the blood, we noted a decreased proportion of natural killer cells in CMV-infected mice. However, no significant difference in plasma cell percentages was observed between CMV-infected and uninfected mice in metastatic lung tissues. The cell-cell interaction analysis further showed a complex crosstalk network between immune cells as well as tumor and immune cells. These findings highlight the profound impact of CMV infection on remodeling the immune landscape at both primary tumors and metastatic sites. The distinct immune cell dynamics orchestrated by CMV infection underscore the virus's role in modifying tumor-immune microenvironments and macroenvironments. Our study offers novel perspectives for developing targeted cancer therapies that consider the complex interactions between viral infections and the tumor immune axis. Further research is warranted to elucidate the mechanisms underlying CMV-mediated immune modulation at molecular level and its potential therapeutic implications in TNBC and other cancer types.
Citation Format: Wenjuan Dong, Jianting Sheng, Shan Xu, Matthew Vasquez, Hong Zhao, Stephen T.C Wong. Cytomegalovirus infection modulates distinct immune cell dynamics across tumor-immune microenvironments and systemic macroenvironment during metastasis [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 C001.