American Association for Cancer Research
10780432ccr173757-sup-194177_2_supp_4618518_p5c3z9.pdf (1.45 MB)

Supplementary figure 2 from Tumor-Derived GM-CSF Promotes Granulocyte Immunosuppression in Mesothelioma Patients

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journal contribution
posted on 2023-03-31, 20:44 authored by Swati Khanna, Suzanne Graef, Francis Mussai, Anish Thomas, Neha Wali, Bahar Guliz Yenidunya, Constance Yuan, Betsy Morrow, Jingli Zhang, Firouzeh Korangy, Tim F. Greten, Seth M. Steinberg, Maryalice Stetler-Stevenson, Gary Middleton, Carmela De Santo, Raffit Hassan

Mesothelioma granulocytes suppress T cell activation


Center for Cancer Research

National Cancer Institute


Cancer Research UK

British Lung Foundation

June Hancock Mesothelioma Research Fund



Purpose: The cross-talk between tumor cells, myeloid cells, and T cells can play a critical role in tumor pathogenesis and response to immunotherapies. Although the etiology of mesothelioma is well understood, the impact of mesothelioma tumor cells on the surrounding immune microenvironment is less well studied. In this study, the effect of the mesothelioma tumor microenvironment on circulating and infiltrating granulocytes and T cells is investigated.Experimental Design: Tumor tissues and peripheral blood from mesothelioma patients were evaluated for presence of granulocytes, which were then tested for their T-cell suppression potential. Different cocultures of granulocytes and/or mesothelioma tumor cells and/or T cells were set up to identify the mechanism of T-cell inhibition.Results: Analysis of human tumors showed that the mesothelioma microenvironment is enriched in infiltrating granulocytes, which inhibit T-cell proliferation and activation. Characterization of the whole blood at diagnosis identified similar, circulating, immunosuppressive CD11b+CD15+HLADR− granulocytes at increased frequency compared with healthy controls. Culture of healthy-donor granulocytes with human mesothelioma cells showed that GM-CSF upregulates NOX2 expression and the release of reactive oxygen species (ROS) from granulocytes, resulting in T-cell suppression. Immunohistochemistry and transcriptomic analysis revealed that a majority of mesothelioma tumors express GM-CSF and that higher GM-CSF expression correlated with clinical progression. Blockade of GM-CSF with neutralizing antibody, or ROS inhibition, restored T-cell proliferation, suggesting that targeting of GM-CSF could be of therapeutic benefit in these patients.Conclusions: Our study presents the mechanism behind the cross-talk between mesothelioma tumors and the immune microenvironment and indicates that targeting GM-CSF could be a novel treatment strategy to augment immunotherapy in patients with mesothelioma. Clin Cancer Res; 24(12); 2859–72. ©2018 AACR.

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