Myoglobin expression boosts T-cell metabolism and antitumor effector function 2306919

Abstract

Abstract Introduction The tumor microenvironment is often highly hypoxic and typically suffers from a marked lack of essential nutrients, including limited glucose availability. Because effector T cells have substantial energy requirements, the altered metabolic conditions created by the tumor can significantly contribute to impaired T-cell function and the development of T-cell exhaustion. Methods In this study, we assessed hypoxia in spleen and tumor tissue of tumor-bearing C57BL/6J mice using RT-PCR, histology, and flow cytometry. CD8+ T cells from C57BL/6J or P14+ mice were transduced with Thy1.1 (control) or Thy1.1—myoglobin (Mb) retrovirus, and Mb expression was verified by RT-PCR and western blot. Cellular metabolism was analyzed using flow cytometry, electron microscopy, Seahorse assays, metabolomics and luminescence-based methods. Mb-expressing or control P14+ or OT-I+ T cells were transferred into B16F10-gp33 or MC38-ova tumor-bearing mice and examined by flow cytometry and histology. Additionally, B16F10-gp33 tumor-bearing mice received anti—PD-1 treatment. Results We show that expression of the oxygen-binding protein myoglobin (Mb) in T cells enhances their mitochondrial and glycolytic metabolism, increasing metabolites, tricarboxylic acid cycle intermediates and ATP. Mb-expressing T cells showed reduced HIF-1α after activation and during tumor infiltration. Consequently, Mb boosted effector T-cell function against tumor cells in vitro while lowering superoxide. After adoptive transfer into tumor-bearing mice, Mb promoted greater T-cell infiltration into the tumor microenvironment. Although Mb-expressing T cells produced more effector cytokines, they still expressed PD-1 and responded to anti—PD-1 treatment, which combined with Mb-T-cell transfer most effectively delayed tumor growth. Conclusion Taken together, our findings show that Mb expression in T cells enhances their metabolic activity, promotes their infiltration into tumor tissue, and improves their effector function against cancer cells. Funding Source This study was supported by the German Research Foundation (DFG, GRK1949, LA2558/8- 1, 417677437GRK2578 & XU 160/3- 1), the Jurgen Manchot Foundation (Molecules of Infection, MOI4/MOI5), the Volkswagen Foundation (9B797), the Medical Faculty of the Heinrich Heine University (Forschungskommission), and the NIH Tetramer Facility, the Deutsche José Carreras Leukämie- Stiftung (DJCLS 18R/2021), the German Childhood Cancer Foundation (A2023/31), the German Federal Office for Radiation Protection (BfS), the DZIF (TTU 07- 711), the German Ministry for Education and Research (Bundesministerium für Bildung und Forschung BMBF, grant no. 01KD2410A (EDI- 4- ALL)), the Luxembourg National Research Fund (FNR) CORE grant (C21/BM/15796788) and the Fondation Luxembourg (Treg HTS). Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)