The Biological Role and Therapeutic Potential of NK Cells in Hematological and Solid Tumors

NKG2C+CD57+ natural killer cells with senescent features are induced during cutaneous leishmaniasis and accumulate in patients with lesional healing impairment

Natural killer (NK) cells include different subsets with diverse effector capacities that are poorly understood in the context of parasitic diseases. Here, we investigated inhibitory and activating receptor expression on NK cells in patients with cutaneous leishmaniasis (CL) and explored their phenotypic and functional heterogeneity based on CD57 and NKG2C expression. The expression of CD57 identified NK cells that accumulated in CL patients and exhibited features of senescence. The CD57+ cells exhibited heightened levels of the activating receptor NKG2C and diminished expression of the inhibitory receptor NKG2A. RNA sequencing analyses based on NKG2C transcriptome have revealed two distinct profiles among CL patients associated with cytotoxic and functional genes. The CD57+NKG2C+ subset accumulated in the blood of patients and presented conspicuous features of senescence, including the expression of markers such as p16, yH2ax, and p38, as well as reduced proliferative capacity. In addition, they positively correlated with the number of days until lesion resolution. This study provides a broad understanding of the NK cell biology during Leishmania infection and reinforces the role of senescent cells in the adverse clinical outcomes of CL.

Enhancing the Anti-Tumor Efficacy of NK Cells on Canine Mammary Tumors through Resveratrol Activation

In order to explore the therapeutic effect of Resveratrol (Res)-activated Natural Killer (NK) cells on canine mammary tumors, this study employed a range of assays, including wound healing, colony formation, Transwell, flow cytometry, and Western blot experiments, to investigate the impact of Res-pretreated NK cells on canine mammary tumor cells in vitro. Additionally, a tumor-bearing mouse model was utilized to further analyze the therapeutic effects of Res-pretreated NK cells in vivo. The results showed that Res enhances the capacity of NK cells to induce apoptosis, pyroptosis, and ferroptosis in canine breast tumor cells, while also augmenting their influence on the migration, invasion, and epithelial-mesenchymal transition of these cells. Furthermore, pretreatment of NK cells with Res significantly amplified their inhibitory effect on breast tumor growth in vivo and promoted tumor tissue apoptosis. Additionally, Res enhanced the recruitment of NK cells to other immune cells in the body. In summary, Res has been shown to enhance the anti-breast-tumor effect of NK cells both in vitro and in vivo, offering a new avenue for optimizing immunotherapy for canine breast tumors.

Methodological Approaches for Increasing the Retroviral Transduction Efficiency of Primary NK Cells

BACKGROUND

The growing attention to NK cells for cancer cell therapy is associated with the need to establish highly efficient protocols for their genetic modification, particularly by retroviral transduction.

OBJECTIVE

In this work, we have optimized several stages of the retroviral-based modification process, and determined the distribution of the amino acid transporter ASCT2 between NK cell subsets.

METHODS

Retroviral particles were produced using the Phoenix Ampho cell line transfected with the calcium phosphate method . We used RD114-based retroviral transduction for lymphocyte cell lines and primary NK cells.

RESULTS

We have determined the optimal time to collect the RD114-pseudotyped viral supernatants resulting in the titer of viral particles required for efficient NK cell modification to be between 48 and 72 hours. Retroviral modification by retronectin-based method did not alter NK cell functional activity and cell survival. We identified differences in the Multiplicity of Infection (MOI) among cell lines that were partially associated with the ASCT2 surface expression. Cells with higher ASCT2 levels were more susceptible to transduction with RD114-pseudotyped viral particles. Higher ASCT2 expression levels were revealed in activated CD57+ and KIR2DL2DL3+ NK cells compared to their negative counterparts.

CONCLUSION

Our findings provide a more nuanced understanding of NK cell transduction, offering valuable insights for improving therapeutic applications involving NK cell modification.

Allogeneic NK cells induce monocyte-to-dendritic cell conversion, control tumor growth, and trigger a pro-inflammatory shift in patient-derived cultures of primary and metastatic colorectal cancer

INTRODUCTION

Natural killer (NK) cells are innate lymphocytes with a key role in the defense against tumors. Recently, allogeneic NK cell-based therapies have gained interest because of their ability to directly lyse tumor cells without inducing graft-versus-host disease. As NK cells are also able to influence the function of other immune cells (most notably dendritic cells (DC)), a better understanding of the effects of allogeneic NK cell products on the host immune system is required. In this study, we analyzed the effects of an allogeneic off-the-shelf NK cell product, on the tumor microenvironment (TME) of primary and metastatic colorectal cancer (pCRC and mCRC, respectively). Moreover, we explored if the combination of NK cells with R848, a toll-like receptors 7/8 ligand, could further enhance any pro-inflammatory effects.

METHODS

Ex vivo expanded umbilical cord blood stem cell derived NK cells were co-cultured with pCRC or mCRC single-cell suspensions in the presence or absence of R848 for 5 days, during and after which flow cytometry and cytokine release profiling were performed.

RESULTS

NK cells efficiently induced lysis of tumor cells in both pCRC and mCRC single-cell suspensions and thereby controlled growth rates during culture. They also induced differentiation of infiltrating monocytic cells to an activated DC phenotype. Importantly, this NK-mediated myeloid conversion was also apparent in cultures after tumor cell depletion and was further enhanced by combining NK cells with R848. Moreover, NK cells, and to a greater extent, the combination of NK cells and R848, triggered CD8+ and CD4+ T-cell activation as well as a reduction in activated regulatory T cell rates. Finally, the combination of NK cells and R848 induced a pro-inflammatory shift in the cytokine release profile resulting in higher levels of interferon (IFN)-γ, interleukin (IL)-2, IL-12p70, and IFN-α as well as a reduction in IL-6, in both pCRC and mCRC cultures.

CONCLUSION

Allogeneic NK cells engaged in favorable myeloid crosstalk, displayed effective antitumor activity and, when combined with R848, induced a pro-inflammatory shift of the CRC TME. These findings prompt the investigation of NK cells and R848 as a combination therapy for solid tumors.

Natural Killer Cells and Immunotherapy

Natural killer (NK) cells are innate immune cells that demonstrate cytolytic activity against tumor cells, virus-infected cells and other physiologically stressed cells, such as senescent cells [...].

Combination of Expanded Allogeneic NK Cells and T Cell-Based Immunotherapy Exert Enhanced Antitumor Effects

Immunotherapies based on immune checkpoint blockade, neoantigen-reactive tumor-infiltrating lymphocytes and T cell receptor-engineered T cells (TCR-T) have achieved favorable clinical outcomes in tumor treatment. However, sustained immune response and tumor regression have been observed only in a few patients due to immune escape. Natural killer (NK) cells can mediate direct tumor lysis and target cancer cells with low or no expression of human leukocyte antigen class I (HLA-I) that are no longer recognized by T cells during immune escape. Therefore, the combination of T cell-based immunotherapy and NK cell therapy is a promising strategy for improving antitumor response and response rate. However, allogeneic NK cells for adoptive cell therapy have been limited by both the required cell number and quality. Here, we developed an efficient manufacturing system that relies on genetically modified K562 cells for the expansion of high-quality NK cells derived from peripheral blood mononuclear cells. NK cells with the optimal expansion and activity were identified by comparing the different culture systems. Furthermore, we demonstrated that the cooperation of NK cells with tumor-reactive T cells or with NY-ESO-1-specific TCR-T cells further enhanced tumors lysis, especially against tumors with downregulated HLA-I expression. The advantages of HLA-mismatch and non-rejection by other allogeneic immune cells demonstrated the potential of "off-the-shelf" NK cells with the capacity to target tumors for immunotherapy. Our results indicate that the combination strategy based on T cell and allogeneic NK cell immunotherapy might have potential for overcoming the barrier of immune incompetence caused by HLA-I downregulation.

Cord Blood-Derived Natural Killer Cell Exploitation in Immunotherapy Protocols: More Than a Promise?

Simple Summary

NK cell anti-tumor activity against hematological malignancies is well-established and many studies support their role in the control of solid tumor growth and metastasis generation. However, tumor microenvironment may affect NK cell function. Ongoing studies are aimed to design novel immunotherapeutic protocols to combine NK cell-based immunotherapy with other therapeutic strategies to improve the anti-tumor NK cell response. In this context, UCB is one of the main sources of both mature NK cells and of CD34⁺ HSPC that can generate NK cells, both in-vivo and in-vitro. UCB-derived NK cells represent a valuable tool to perform in-vitro and preclinical analyses and are already used in several clinical settings, particularly against hematological malignancies. The present review describes the characteristics of different types of UCB-derived NK cells and the in-vitro models to expand them, both for research and clinical purposes in the context of cancer immunotherapy.

Abstract

In the last 20 years, Natural Killer (NK) cell-based immunotherapy has become a promising approach to target various types of cancer. Indeed, NK cells play a pivotal role in the first-line defense against tumors through major histocompatibility complex-independent immunosurveillance. Their role in the control of leukemia relapse has been clearly established and, moreover, the presence of NK cells in the tumor microenvironment (TME) generally correlates with good prognosis. However, it has also been observed that, often, NK cells poorly infiltrate the tumor tissue, and, in TME, their functions may be compromised by immunosuppressive factors that contribute to the failure of anti-cancer immune response. Currently, studies are focused on the design of effective strategies to expand NK cells and enhance their cytotoxic activity, exploiting different cell sources, such as peripheral blood (PB), umbilical cord blood (UCB) and NK cell lines. Among them, UCB represents an important source of mature NK cells and CD34⁺ Hematopoietic Stem and Progenitor Cells (HSPCs), as precursors of NK cells. In this review, we summarize the UCB-derived NK cell activity in the tumor context, review the different in-vitro models to expand NK cells from UCB, and discuss the importance of their exploitation in anti-tumor immunotherapy protocols.

The yin–yang effects of immunity: From monoclonal gammopathy of undetermined significance to multiple myeloma

Multiple myeloma (MM) is the third most common malignant neoplasm of the hematological system. It often develops from monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) precursor states. In this process, the immune microenvironment interacts with the MM cells to exert yin and yang effects, promoting tumor progression on the one hand and inhibiting it on the other. Despite significant therapeutic advances, MM remains incurable, and the main reason for this may be related to the complex and variable immune microenvironment. Therefore, it is crucial to investigate the dynamic relationship between the immune microenvironment and tumors, to elucidate the molecular mechanisms of different factors in the microenvironment, and to develop novel therapeutic agents targeting the immune microenvironment of MM. In this paper, we review the latest research progress and describe the dual influences of the immune microenvironment on the development and progression of MM from the perspective of immune cells and molecules.

Venetoclax enhances NK cell killing sensitivity of AML cells through the NKG2D/NKG2DL activation pathway

BACKGROUND

Venetoclax, a selective B-cell lymphoma-2 (BCL2) inhibitor, has a potential therapeutic effect when combined with demethylating agents in the first-line setting of unfit elderly patients with acute myeloid leukaemia (AML); however, efficacy is still limited in refractory/recurrent AML. Therefore, exploration of a suitable novel treatment scheme is urgently needed.However, combining venetoclax with NK cell-based immunotherapy has not been studied.

METHODS

The cytotoxicity of NK cell combined with venetoclax was assessed in vitro using flow cytometry. Venetoclax-induced natural killer group 2 member D (NKG2D) ligand (NKG2DL) expression was detected by flow cytometry and western blotting. Mechanisms underlying venetoclax-induced NKG2DL expression were found by GSE127200 analysis and investigated using real-time PCR (Q-PCR) and western blotting.

RESULTS

Flow cytometric analysis showed that combining venetoclax with NK cells produced synergistic anti-leukaemia effects similar to those of venetoclax + azacitidine. Venetoclax could render AML cell lines and primary AML cells sensitive to NK cell killing by promoting NK cell degranulation, NK-AML cell recognition and NK cell secretion of interferon (IFN)-γ and granzyme B. The synergistic effect resulted from venetoclax-induced NKG2DL upregulation in AML cells and could be undermined by blocking NKG2D on NK cells. This finding suggests that venetoclax enhances NK cell killing activity by activating the NKG2D/NKG2DL ligand-receptor pathway. Furthermore, the nuclear factor-kappa-B (NFKB) signalling pathway was involved in venetoclax-induced NKG2DL upregulation.

CONCLUSIONS

Collectively, our data confirm that venetoclax combined with NK cells induces synergistic AML cell cytolysis and preliminarily revealed that venetoclax could selectively induce NKG2DLs on AML cells via NFKB signalling pathway.