From CMV to cancer : the immunological power of adaptive NK cells

Natural killer (NK) cells are key players in the immune response against many viral infections and malignancies, bridging innate and adaptive immunity. A subset of NK cells, adaptive NK (aNK) cells, display memory-like properties-such as the ability to respond more robustly upon re-exposure to stimuli-alongside enhanced cytotoxicity and metabolic adaptability, which refers to their capacity to reprogram energy usage depending on environmental cues. These features position aNK cells as promising candidates for cancer immunotherapy. This thesis explores the interplay between cytomegalovirus (CMV) and aNK cells, focusing on their role in inflammation and the tumor microenvironment of glioblastoma (GBM). GBM was chosen as a primary model due to its reported association with CMV, including the detection of CMV proteins within tumor tissues, which suggests a potential viral contribution to disease progression and immune modulation. GBM is an aggressive brain tumor with a highly immunosuppressive environment and a critical need for novel therapeutic approaches.

In Paper I, we explore the role of CMV in shaping the inflammatory landscape of colorectal cancer. We demonstrate that CMV infection upregulates cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO), key inflammatory mediators, thereby promoting tumor progression. Targeting both viral infection and inflammation using antiviral and anti-inflammatory agents reduced tumor cell proliferation, highlighting them for potential therapeutic strategies.

Paper II investigates antigen-specific interactions between aNK cells and HLA-E- expressing dendritic cells (DCs). We identify novel CMV-derived peptides that stabilize HLA-E and enhance aNK cell activation via NKG2C. This study establishes aNK cells as antigen-responsive effectors with memory-like properties, providing insights into harnessing NKG2C-HLA-E interactions for cancer immunotherapy.

In Paper III, we optimize an ex vivo expansion strategy for aNK cells using IL-15, IL- 21, two cytokines that have demonstrated to be important in NK cell proliferation and survival; and tumor lysates, enhancing their persistence and cytotoxic potential. Using a zebrafish xenograft model, we demonstrate that aNK cells exhibit superior anti-tumor activity compared to conventional NK (CNK) cells when they are culture in the presence of IL-15 and IL-21 together with K562E feeder cells loaded with tumor antigens, supporting their use in adoptive cell therapy.

Paper IV explores the metabolic adaptability of aNK cells in GBM. We show that aNK cells maintain their infiltration of tumor spheroids and cytotoxicity in a suppressive TME. Unlike cNK cells, aNK cells can utilize different metabolic pathways for their activation, highlighting their superior metabolic flexibility.

This thesis highlights the potential of aNK cells in cancer immunotherapy, focusing on their antigen recognition, metabolism, and role in solid tumors. By targeting viral-driven inflammation, enhancing NKG2C-HLA-E interactions, and improving metabolic adaptability, we propose strategies to boost NK cell therapies and counteract tumor immune suppression.

List of scientific papers

I. Pantalone MR, Martín Almazán N, Lattanzio R, Taher C, De Fabritiis S, Valentinuzzi S, Bishehsari F, Mahdavinia M, Verginelli F, Rahbar A, Mariani-Costantini R, Söderberg-Naucler C. Human cytomegalovirus infection enhances 5-lipoxygenase and cycloxygenase-2 expression in colorectal cancer. Int J Oncol. 2023 Nov;63(5):116. Epub 2023 Sep 1. https://doi.org/10.3892/ijo.2023.5564

II. Martín Almazán N*, Sala BM*, Sandalova T, Sun Y, Resink T, Cichocki F, Söderberg-Naucler C, Miller JS, Achour A, Sarhan D. Non-classical HLA-E restricted CMV 15-mer peptides are recognized by adaptive NK cells and induce memory responses. Front Immunol. 2023 Sep 21;14:1230718. https://doi.org/10.3389/fimmu.2023.1230718

III. Martín Almazán N*, Román S*, Sun Y, Bräutigam L, Pantalone MR, Stragliotto G, Gultekin O, Söderberg-Nauclér C, Saheli S, Lehti K, Sarhan D. Advancing Adoptive Cell Therapy: Optimized Expansion of Adaptive NK Cells for Solid Tumors. BioRxiv 2024, Oct. [Manuscript Preprint] https://doi.org/10.1101/2024.10.02.616358

IV. Martín Almazán N, Hahn P, Calvera A, Damdimopoulos A, Sarhan D* and Söderberg-Naucler C *. Study the immune metabolism and metabolic flexibility of adaptive NK cells in the glioblastoma tumor microenvironment. [Manuscript]