Interleukin-15-Cultured Dendritic Cells Enhance Anti-Tumor Gamma Delta T Cell Functions through IL-15 Secretion

IL-15 as a key regulator in NK cell-mediated immunotherapy for cancer: From bench to bedside

Interleukin 15 (IL-15) has emerged as a crucial factor in the relationship between natural killer (NK) cells and immunotherapy for cancer. This review article aims to provide a comprehensive understanding of the role of IL-15 in NK cell-mediated immunotherapy. First, the key role of IL-15 signaling in NK cell immunity is discussed, highlighting its regulation of NK cell functions and antitumor properties. Furthermore, the use of IL-15 or its analogs in clinical trials as a therapeutic strategy for various cancers, including the genetic modification of NK cells to produce IL-15, has been explored. The potential of IL-15-based therapies, such as chimeric antigen receptor (CAR) T and NK cell infusion along with IL-15 in combination with checkpoint inhibitors and other treatments, has been examined. This review also addresses the challenges and advantages of incorporating IL-15 in cell-based immunotherapy. Additionally, unresolved questions regarding the detection and biological significance of the soluble IL-15/IL-15Rα complex, as well as the potential role of IL-15/IL-15Rα in human cancer and the immunological consequences of prolonged exposure to soluble IL-15 for NK cells, are discussed.

Effective γδ T-cell clinical therapies: current limitations and future perspectives for cancer immunotherapy

γδ T cells are a unique subset of T lymphocytes, exhibiting features of both innate and adaptive immune cells and are involved with cancer immunosurveillance. They present an attractive alternative to conventional T cell-based immunotherapy due, in large part, to their lack of major histocompatibility (MHC) restriction and ability to secrete high levels of cytokines with well-known anti-tumour functions. To date, clinical trials using γδ T cell-based immunotherapy for a range of haematological and solid cancers have yielded limited success compared with in vitro studies. This inability to translate the efficacy of γδ T-cell therapies from preclinical to clinical trials is attributed to a combination of several factors, e.g. γδ T-cell agonists that are commonly used to stimulate populations of these cells have limited cellular uptake yet rely on intracellular mechanisms; administered γδ T cells display low levels of tumour-infiltration; and there is a gap in the understanding of γδ T-cell inhibitory receptors. This review explores the discrepancy between γδ T-cell clinical and preclinical performance and offers viable avenues to overcome these obstacles. Using more direct γδ T-cell agonists, encapsulating these agonists into lipid nanocarriers to improve their pharmacokinetic and pharmacodynamic profiles and the use of combination therapies to overcome checkpoint inhibition and T-cell exhaustion are ways to bridge the gap between preclinical and clinical success. Given the ability to overcome these limitations, the development of a more targeted γδ T-cell agonist-checkpoint blockade combination therapy has the potential for success in clinical trials which has to date remained elusive.

Human gamma-delta (γδ) T cell therapy for glioblastoma: A novel alternative to overcome challenges of adoptive immune cell therapy

Glioblastoma is the most common brain malignancy with devastating prognosis. Numerous clinical trials using various target therapeutic agents have failed and recent clinical trials using check point inhibitors also failed to provide survival benefits for glioblastoma patients. Adoptive T cell transfer is suggested as a novel therapeutic approach that has exhibited promise in preliminary clinical studies. However, the clinical outcomes are inconsistent, and there are several limitations of current adoptive T cell transfer strategies for glioblastoma treatment. As an alternative cell therapy, gamma-delta (γδ) T cells have been recently introduced for several cancers including glioblastoma. Since the leading role of γδ T cells is immune surveillance by recognizing a broad range of ligands including stress molecules, phosphoantigens, or lipid antigens, recent studies have suggested the potential benefits of γδ T cell transfer against glioblastomas. However, γδ T cells, as a small subset (1-5%) of T cells in human peripheral blood, are relatively unknown compared to conventional alpha-beta (αβ) T cells. In this context, our study introduced γδ T cells as an alternative and novel option to overcome several challenges regarding immune cell therapy in glioblastoma treatment. We described the unique characteristics and advantages of γδ T cells compared to conventional αβ T cells and summarize several recent preclinical studies using human gamma-delta T cell therapy for glioblastomas. Finally, we suggested future direction of human γδ T cell therapy for glioblastomas.

The intestinal γδ T cells: functions in the gut and in the distant organs

Located in the frontline against the largest population of microbiota, the intestinal mucosa of mammals has evolved to become an effective immune system. γδ T cells, a unique T cell subpopulation, are rare in circulation blood and lymphoid tissues, but rich in the intestinal mucosa, particularly in the epithelium. Via rapid production of cytokines and growth factors, intestinal γδ T cells are key contributors to epithelial homeostasis and immune surveillance of infection. Intriguingly, recent studies have revealed that the intestinal γδ T cells may play novel exciting functions ranging from epithelial plasticity and remodeling in response to carbohydrate diets to the recovery of ischemic stroke. In this review article, we update regulatory molecules newly defined in lymphopoiesis of the intestinal γδ T cells and their novel functions locally in the intestinal mucosa, such as epithelial remodeling, and distantly in pathological setting, e.g., ischemic brain injury repair, psychosocial stress responses, and fracture repair. The challenges and potential revenues in intestinal γδ T cell studies are discussed.

Innate lymphoid cells and innate-like T cells in cancer - at the crossroads of innate and adaptive immunity

Immunotherapies targeting conventional T cells have revolutionized systemic treatment for many cancers, yet only a subset of patients benefit from these approaches. A better understanding of the complex immune microenvironment of tumours is needed to design the next generation of immunotherapeutics. Innate lymphoid cells (ILCs) and innate-like T cells (ILTCs) are abundant, tissue-resident lymphocytes that have recently been shown to have critical roles in many types of cancers. ILCs and ILTCs rapidly respond to changes in their surrounding environment and act as the first responders to bridge innate and adaptive immunity. This places ILCs and ILTCs as pivotal orchestrators of the final antitumour immune response. In this Review, we outline hallmarks of ILCs and ILTCs and discuss their emerging role in antitumour immunity, as well as the pathophysiological adaptations leading to their pro-tumorigenic function. We explore the pleiotropic, in parts redundant and sometimes opposing, mechanisms that underlie the delicate interplay between the different subsets of ILCs and ILTCs. Finally, we highlight their role in amplifying and complementing conventional T cell functions and summarize immunotherapeutic strategies for targeting ILCs and ILTCs in cancer.

Exhausted intratumoral Vδ2- γδ T cells in human kidney cancer retain effector function

Gamma delta (γδ) T cells reside within human tissues including tumors, but their function in mediating antitumor responses to immune checkpoint inhibition is unknown. Here we show that kidney cancers are infiltrated by Vδ2- γδ T cells, with equivalent representation of Vδ1+ and Vδ1- cells, that are distinct from γδ T cells found in normal human tissues. These tumor-resident Vδ2- T cells can express the transcriptional program of exhausted αβ CD8+ T cells as well as canonical markers of terminal T-cell exhaustion including PD-1, TIGIT and TIM-3. Although Vδ2- γδ T cells have reduced IL-2 production, they retain expression of cytolytic effector molecules and co-stimulatory receptors such as 4-1BB. Exhausted Vδ2- γδ T cells are composed of three distinct populations that lack TCF7, are clonally expanded and express cytotoxic molecules and multiple Vδ2- T-cell receptors. Human tumor-derived Vδ2- γδ T cells maintain cytotoxic function and pro-inflammatory cytokine secretion in vitro. The transcriptional program of Vδ2- T cells in pretreatment tumor biopsies was used to predict subsequent clinical responses to PD-1 blockade in patients with cancer. Thus, Vδ2- γδ T cells within the tumor microenvironment can contribute to antitumor efficacy.

Methylation changes induced by a glycodendropeptide immunotherapy and associated to tolerance in mice

Introduction

Allergen-specific immunotherapy (AIT) is applied as treatment to rise tolerance in patients with food allergies. Although AIT is thoroughly used, the underlying epigenetic events related to tolerant induction are still unknown. Thus, we aim to investigate epigenetic changes that could be related to tolerance in dendritic cells (DCs) from anaphylactic mice to lipid transfer proteins, Pru p 3, in the context of a sublingual immunotherapy (SLIT) with a glycodendropeptide (D1ManPrup3) that has demonstrated tolerant or desensitization responses depending on the treatment dose.

Methods

Changes in DNA methylation in CpG context were determined comparing Sensitized (Antigen-only) animals and two groups receiving SLIT with the D1ManPrup3 nanostructure (D1ManPrup3-SLIT): Tolerant (2nM D1ManPrup3) and Desensitized (5nM D1ManPrup3), against anaphylactic animals. DNA from lymph nodes-DCs were isolated and then, Whole Genome Bisulphite Sequencing was performed to analyze methylation.

Results

Most differentially methylated regions were found on the area of influence of gene promoters (DMPRs). Compared to the Anaphylactic group, the highest value was found in Desensitized mice (n = 7,713 DMPRs), followed by Tolerant (n = 4,091 DMPRs) and Sensitized (n = 3,931 DMPRs) mice. Moreover, many of these epigenetic changes were found in genes involved in immune and tolerance responses (Il1b, Il12b, Il1a, Ifng, and Tnf) as shown by functional enrichment (DCs regulation, B cell-mediated immunity, and effector mechanisms).

Discussion

In conclusion, different doses of D1ManPrup3-SLIT induce different DNA methylation changes, which are reflected in the induction of distinct responses, tolerance, or desensitization.

IFN-γ and TGF-β, Crucial Players in Immune Responses: A Tribute to Howard Young

Interferon gamma (IFN-γ) and transforming growth factor beta (TGF-β), both pleiotropic cytokines, have been long studied and described as critical mediators of the immune response, notably in T cells. One of the investigators who made seminal and critical discoveries in the field of IFN-γ biology is Dr. Howard Young. In this review, we provide an overview of the biology of IFN-γ as well as its role in cancer and autoimmunity with an emphasis on Dr. Young's critical work in the field. We also describe how Dr. Young's work influenced our own research studying the role of TGF-β in the modulation of immune responses.

Exercise-induced IL-15 acted as a positive prognostic implication and tumor-suppressed role in pan-cancer

Objective: Exercise can produce a large number of cytokines that may benefit cancer patients, including Interleukin 15 (IL-15). IL-15 is a cytokine that has multiple functions in regulating the adaptive and innate immune systems and tumorigenesis of lung and breast cancers. However, the roles of IL-15 in other types of cancer remain unknown. In this article, we try to systematically analyze if IL-15 is a potential molecular biomarker for predicting patient prognosis in pan-cancer and its connection with anti-cancer effects of exercise. Methods: The expression of IL-15 was detected by The Cancer Genome Atlas (TCGA) database, Human protein Atlas (HPA), and Genotype Tissue-Expression (GTEX) database. Analysis of IL-15 genomic alterations and protein expression in human organic tissues was analyzed by the cBioPortal database and HPA. The correlations between IL-15 expression and survival outcomes, clinical features, immune-associated cell infiltration, and ferroptosis/cuproptosis were analyzed using the TCGA, ESTIMATE algorithm, and TIMER databases. Gene Set Enrichment Analysis (GSEA) was performed to evaluate the biological functions of IL-15 in pan-cancer. Results: The differential analysis suggested that the level of IL-15 mRNA expression was significantly downregulated in 12 tumor types compared with normal tissues, which is similar to the protein expression in most cancer types. The high expression of IL-15 could predict the positive survival outcome of patients with LUAD (lung adenocarcinoma), COAD (colon adenocarcinoma), COADREAD (colon and rectum adenocarcinoma), ESCA (esophageal carcinoma), SKCM (skin cutaneous melanoma), UCS (uterine carcinosarcoma), and READ (rectum adenocarcinoma). Moreover, amplification was found to be the most frequent mutation type of IL-15 genomic. Furthermore, the expression of IL-15 was correlated to the infiltration levels of various immune-associated cells in pan-cancer assessed by the ESTIMATE algorithm and TIMER database. In addition, IL-15 is positively correlated with ferroptosis/cuproptosis-related genes (ACSL4 and LIPT1) in pan-cancer. Levels of IL-15 were reported to be elevated in humans for 10-120 min following an acute exercise. Therefore, we hypothesized that the better prognosis of pan-cancer patients with regular exercise may be achieved by regulating level of IL-15. Conclusion: Our results demonstrated that IL-15 is a potential molecular biomarker for predicting patient prognosis, immunoreaction, and ferroptosis/cuproptosis in pan-cancer and partly explained the anti-cancer effects of exercise.

γδ T Cells in the Tumor Microenvironment-Interactions With Other Immune Cells

A growing number of studies have shown that γδ T cells play a pivotal role in mediating the clearance of tumors and pathogen-infected cells with their potent cytotoxic, cytolytic, and unique immune-modulating functions. Unlike the more abundant αβ T cells, γδ T cells can recognize a broad range of tumors and infected cells without the requirement of antigen presentation via major histocompatibility complex (MHC) molecules. Our group has recently demonstrated parts of the mechanisms of T-cell receptor (TCR)-dependent activation of Vγ9Vδ2+ T cells by tumors following the presentation of phosphoantigens, intermediates of the mevalonate pathway. This process is mediated through the B7 immunoglobulin family-like butyrophilin 2A1 (BTN2A1) and BTN3A1 complexes. Such recognition results in activation, a robust immunosurveillance process, and elicits rapid γδ T-cell immune responses. These include targeted cell killing, and the ability to produce copious quantities of cytokines and chemokines to exert immune-modulating properties and to interact with other immune cells. This immune cell network includes αβ T cells, B cells, dendritic cells, macrophages, monocytes, natural killer cells, and neutrophils, hence heavily influencing the outcome of immune responses. This key role in orchestrating immune cells and their natural tropism for tumor microenvironment makes γδ T cells an attractive target for cancer immunotherapy. Here, we review the current understanding of these important interactions and highlight the implications of the crosstalk between γδ T cells and other immune cells in the context of anti-tumor immunity.

Harnessing Unconventional T Cells and Innate Lymphoid Cells to Prevent and Treat Hematological Malignancies: Prospects for New Immunotherapy

Unconventional T cells and innate lymphoid cells (ILCs) make up a heterogeneous set of cells that characteristically show prompt responses toward specific antigens. Unconventional T cells recognize non-peptide antigens, which are bound and presented by diverse non-polymorphic antigen-presenting molecules and comprise γδ T cells, MR1-restricted mucosal-associated invariant T cells (MAITs), and natural killer T cells (NKTs). On the other hand, ILCs lack antigen-specific receptors and act as the innate counterpart to the T lymphocytes found in the adaptive immune response. The alteration of unconventional T cells and ILCs in frequency and functionality is correlated with the onset of several autoimmune diseases, allergy, inflammation, and tumor. However, depending on the physio-pathological framework, unconventional T cells may exhibit either protective or pathogenic activity in a range of neoplastic diseases. Nonetheless, experimental models and clinical studies have displayed that some unconventional T cells are potential therapeutic targets, as well as prognostic and diagnostic markers. In fact, cell-mediated immune response in tumors has become the focus in immunotherapy against neoplastic disease. This review concentrates on the present knowledge concerning the function of unconventional T cell sets in the antitumor immune response in hematological malignancies, such as acute and chronic leukemia, multiple myeloma, and lymphoproliferative disorders. Moreover, we discuss the possibility that modulating the activity of unconventional T cells could be useful in the treatment of hematological neoplasms, in the prevention of specific conditions (such as graft versus host disease), and in the formulation of an effective anticancer vaccine therapy. The exact knowledge of the role of these cells could represent the prerequisite for the creation of a new form of immunotherapy for hematological neoplasms.

The role of γδ T cells in the interaction between commensal and pathogenic bacteria in the intestinal mucosa

The intestinal mucosa is an important structure involved in resistance to pathogen infection. It is mainly composed of four barriers, which have different but interrelated functions. Pathogenic bacteria can damage these intestinal mucosal barriers. Here, we mainly review the mechanisms of pathogen damage to biological barriers. Most γδ T cells are located on the surface of the intestinal mucosa, with the ability to migrate and engage in crosstalk with microorganisms. Commensal bacteria are involved in the activation and migration of γδ T cells to monitor the invasion of pathogens. Pathogen invasion alters the migration pattern of γδ T cells. γδ T cells accelerate pathogen clearance and limit opportunistic invasion of commensal bacteria. By discussing these interactions among γδ T cells, commensal bacteria and pathogenic bacteria, we suggest that γδ T cells may link the interactions between commensal bacteria and pathogenic bacteria.

Anti-Tumor Potency of Short-Term Interleukin-15 Dendritic Cells Is Potentiated by In Situ Silencing of Programmed-Death Ligands

Dendritic cell (DC) vaccines have proven to be a valuable tool in cancer immune therapy. With several DC vaccines being currently tested in clinical trials, knowledge about their therapeutic value has been significantly increased in the past decade. Despite their established safety, it has become clear that objective clinical responses are not yet robust enough, requiring further optimization. Improvements of this advanced therapy medicinal product encompass, among others, regulating their immune stimulating capacity by in situ gene engineering, in addition to their implementation in combination therapy regimens. Previously, we have reported on a superior monocyte-derived DC preparation, including interleukin-15, pro-inflammatory cytokines and immunological danger signals in the culture process. These so-called IL-15 DCs have already proven to exhibit several favorable properties as cancer vaccine. Evolving research into mechanisms that could further modulate the immune response towards cancer, points to programmed death-1 as an important player that dampens anti-tumor immunity. Aiming at leveraging the immunogenicity of DC vaccines, we hypothesized that additional implementation of the inhibitory immune checkpoint molecules programmed death-ligand (PD-L)1 and PD-L2 in IL-15 DC vaccines would exhibit superior stimulatory potential. In this paper, we successfully implemented PD-L silencing at the monocyte stage in the 3-day IL-15 DC culture protocol resulting in substantial downregulation of both PD-L1 and PD-L2 to levels below 30%. Additionally, we validated that these DCs retain their specific characteristics, both at the level of phenotype and interferon gamma secretion. Evaluating their functional characteristics, we demonstrate that PD-L silencing does not affect the capacity to induce allogeneic proliferation. Ultimately designed to induce a durable tumor antigen-specific immune response, PD-L silenced IL-15 DCs were capable of surpassing PD-1-mediated inhibition by antigen-specific T cells. Further corroborating the superior potency of short-term IL-15 DCs, the combination of immune stimulatory components during DC differentiation and maturation with in situ checkpoint inhibition supports further clinical translation.

Research progress on dendritic cell vaccines in cancer immunotherapy

Dendritic cell (DC) vaccines induce specific immune responses that can selectively eliminate target cells. In recent years, many studies have been conducted to explore DC vaccination in the treatment of hematological malignancies, including acute myeloid leukemia and myelodysplastic syndromes, as well as other nonleukemia malignancies. There are at least two different strategies that use DCs to promote antitumor immunity: in situ vaccination and canonical vaccination. Monocyte-derived DCs (mo-DCs) and leukemia-derived DCs (DCleu) are the main types of DCs used in vaccines for AML and MDS thus far. Different cancer-related molecules such as peptides, recombinant proteins, apoptotic leukemic cells, whole tumor cells or lysates and DCs/DCleu containing a vaster antigenic repertoire with RNA electroporation, have been used as antigen sources to load DCs. To enhance DC vaccine efficacy, new strategies, such as combination with conventional chemotherapy, monospecific/bispecific antibodies and immune checkpoint-targeting therapies, have been explored. After a decade of trials and tribulations, much progress has been made and much promise has emerged in the field. In this review we summarize the recent advances in DC vaccine immunotherapy for AML/MDS as well as other nonleukemia malignancies.

Phenotypic plasticity of myeloid cells in glioblastoma development, progression, and therapeutics

Glioblastoma (GBM) is the most common and malignant type of intracranial tumors with poor prognosis. Accumulating evidence suggests that phenotypic alterations of infiltrating myeloid cells in the tumor microenvironment are important for GBM progression. Conventional tumor immunotherapy commonly targets T-cells, while innate immunity as a therapeutic target is an emerging field. Targeting infiltrating myeloid cells that induce immune suppression in the TME provides a novel direction to improve the prognosis of patients with GBM. The factors released by tumor cells recruit myeloid cells into tumor bed and reprogram infiltrating myeloid cells into immunostimulatory/immunosuppressive phenotypes. Reciprocally, infiltrating myeloid cells, especially microglia/macrophages, regulate GBM progression and affect therapeutic efficacy. Herein, we revisited biological characteristics and functions of infiltrating myeloid cells and discussed the recent advances in immunotherapies targeting infiltrating myeloid cells in GBM. With an evolving understanding of the complex interactions between infiltrating myeloid cells and tumor cells in the tumor microenvironment, we will expand novel immunotherapeutic regimens targeting infiltrating myeloid cells in GBM treatment and improve the outcomes of GBM patients.

γδ T Cells for Leukemia Immunotherapy: New and Expanding Trends

Recently, many discoveries have elucidated the cellular and molecular diversity in the leukemic microenvironment and improved our knowledge regarding their complex nature. This has allowed the development of new therapeutic strategies against leukemia. Advances in biotechnology and the current understanding of T cell-engineering have led to new approaches in this fight, thus improving cell-mediated immune response against cancer. However, most of the investigations focus only on conventional cytotoxic cells, while ignoring the potential of unconventional T cells that until now have been little studied. γδ T cells are a unique lymphocyte subpopulation that has an extensive repertoire of tumor sensing and may have new immunotherapeutic applications in a wide range of tumors. The ability to respond regardless of human leukocyte antigen (HLA) expression, the secretion of antitumor mediators and high functional plasticity are hallmarks of γδ T cells, and are ones that make them a promising alternative in the field of cell therapy. Despite this situation, in particular cases, the leukemic microenvironment can adopt strategies to circumvent the antitumor response of these lymphocytes, causing their exhaustion or polarization to a tumor-promoting phenotype. Intervening in this crosstalk can improve their capabilities and clinical applications and can make them key components in new therapeutic antileukemic approaches. In this review, we highlight several characteristics of γδ T cells and their interactions in leukemia. Furthermore, we explore strategies for maximizing their antitumor functions, aiming to illustrate the findings destined for a better mobilization of γδ T cells against the tumor. Finally, we outline our perspectives on their therapeutic applicability and indicate outstanding issues for future basic and clinical leukemia research, in the hope of contributing to the advancement of studies on γδ T cells in cancer immunotherapy.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

The subtle interplay between gamma delta T lymphocytes and dendritic cells: is there a role for a therapeutic cancer vaccine in the era of combinatorial strategies?

Human gamma delta (γδ) T cells represent heterogeneous subsets of unconventional lymphocytes with an HLA-unrestricted target cell recognition. γδ T cells display adaptive clonally restricted specificities coupled to a powerful cytotoxic function against transformed/injured cells. Dendritic cells (DCs) are documented to be the most potent professional antigen-presenting cells (APCs) able to induce adaptive immunity and support the innate immune response independently from T cells. Several data show that the cross-talk of γδ T lymphocytes with DCs can play a crucial role in the orchestration of immune response by bridging innate to adaptive immunity. In the last decade, DCs, as well as γδ T cells, have been of increasing clinical interest, especially as monotherapy for cancer immunotherapy, even though with unpredictable results mainly due to immune suppression and/or tumor-immune escape. For these reasons, new vaccine strategies have to be explored to reach cancer immunotherapy's full potential. The effect of DC-based vaccines on γδ T cell is less extensively investigated, and a combinatorial approach using DC-based vaccines with γδ T cells might promote a strong synergy for long-term tumor control and protection against escaping tumor clones. Here, we discuss the therapeutic potential of the interaction between DCs and γδ T cells to improve cancer vaccination. In particular, we describe the most relevant and updated evidence of such combinatorial approaches, including the use of Zoledronate, Interleukin-15, and protamine RNA, also looking towards future strategies such as CAR therapies.

Therapeutic potential of interleukin-15 in cancer (Review)

The immune system is dysfunctional in cancer, and therapeutic approaches designated to restore immunity and increase long-term overall survival are desirable. The role of immunotherapy is to trigger the immune system to recognize and destroy tumor cells. Interleukin-15 (IL-15) is a member of the common gamma-chain (γc) cytokines that promote the differentiation and expansion of T cells, B cells and natural killer (NK) cells, leading to enhanced antitumor responses. This suggests that IL-15 is a promising candidate for anticancer therapy. Renewed interest in cancer immunotherapy has led to an increased number of preclinical studies and clinical trials that have investigated the reliability and potency of IL-15-based agents, not only as single therapy, but also in combination with others. This review provides a description of these studies which show the advantages and disadvantages of IL-15 as an immunotherapeutic agent. We present here the role of IL-15 and pharmacologically improved IL-15 superagonists as a single treatment or in combination with other therapeutic agents.

The role of various interleukins in acute myeloid leukemia

Interleukins are signaling molecules involved in the immune system, and they play a variety of roles in different diseases and cancers. Acute myeloid leukemia (AML) is the most common type of leukemia in adults, and survival rate after diagnosis is very low. Investigating the role interleukins play in AML can help understand the progression of the disease. There exists a need for more effective treatment of AML. Interleukins can be used to guide immunotherapy for AML. This review article will examine how specific interleukins play a role in AML disease progression and how they can be utilized as a future treatment option.

Biological effects of IL-15 on immune cells and its potential for the treatment of cancer

Interleukin-15 (IL-15) has recently emerged as a novel immunomodulatory cytokine in cancer immunotherapy. IL-15 has the potential to reject and destroy cancer cells in the tumor microenvironment by expanding and activating natural killer (NK), natural killer T (NKT), and memory (m) CD8+T cells. Due to the feasible outcomes obtained from preclinical studies and phase 1/2 clinical trials, IL-15-based therapy, including chimeric antigen receptor (CAR) T cell or CAR NK cell infusion following in vitro expansion in the presence of IL-15, used in combination with checkpoint inhibitors and other therapy may extend to clinical practice in the future. It is also important to understand the biological characteristics of IL-15 to ensure the maximal benefit of therapeutic strategies. Here, we summarize the current development of IL-15 in the following areas: anti-tumor mechanisms in the tumor microenvironment, advances in IL-15-based therapy itself or in combination with other methods, including biological agents, monoclonal antibodies, and adoptive immunotherapy.

Alterations in peripheral blood monocyte and dendritic cell subset homeostasis in relapsing-remitting multiple sclerosis patients

Antigen-presenting cells participate and are implicated in the pathogenesis of multiple sclerosis. In our study we assessed the frequency of plasmacytoid (pDC) and myeloid (mDC) dendritic cells and the classical, intermediate and non-classical monocytes subsets, as well as their phenotypic and functional profile. We evaluated peripheral blood from relapsing-remitting patients treated with IFN-β in remission and relapse phases and from healthy subjects. In remission, we observed a decrease of mDC/pDC ratio and a return to normal values in relapse. In both phases the frequency of non-classical monocytes decreases. Concerning the phenotypic characterization, an increased HLA-DR expression was observed in remission and a decrease in relapse, revealing alterations in monocytes and dendritic cells homeostasis.

Immune Effects of γδ T Cells in Colorectal Cancer: A Review

Gamma delta (γδ) T cells can effectively recognize and kill colorectal cancer (CRC) cells, thereby suppressing tumor progression via multiple mechanisms. They also have abilities to exert a protumor effect via secreting interleukin-17 (IL-17). γδ T cells have been selected as potential immunocytes for antitumor treatment because of their significant cytotoxic activity. Immunotherapy is another potential anti-CRC strategy after an operation, chemotherapy, and radiotherapy. γδ T cell-based immunotherapy for CRC shows fewer side effects and better toleration. This review will outline the immune functions and the mechanisms of γδ T cells in the growth and progression of CRC in recent years, and summarize the immunotherapies based on γδ T cells, thus providing a direction for future γδ T cells in CRC research.

Expansion With IL-15 Increases Cytotoxicity of Vγ9Vδ2 T Cells and Is Associated With Higher Levels of Cytotoxic Molecules and T-bet

Cancer immunotherapy has shown great advances during recent years, but it has yet to reach its full potential in all cancer types. Adoptive cell therapy (ACT) is now an approved treatment option for certain hematological cancers and has also shown success for some solid cancers. Still, benefit and eligibility do not extend to all patients. ACT with Vγ9Vδ2 T cells is a promising approach to overcome this hurdle. In this study, we aimed to explore the effect of different cytokine conditions on the expansion of Vγ9Vδ2 T cells in vitro. We could show that Vγ9Vδ2 T cell expansion is feasible with two different cytokine conditions: (a) 1,000 U/ml interleukin (IL)-2 and (b) 100 U/ml IL-2 + 100 U/ml IL-15. We did not observe differences in expansion rate or Vγ9Vδ2 T cell purity between the conditions; however, IL-2/IL-15-expanded Vγ9Vδ2 T cells displayed enhanced cytotoxicity against tumor cells, also in hypoxia. While this increase in killing capacity was not reflected in natural killer (NK) cell marker or activation marker expression, we demonstrated that IL-2/IL-15-expanded Vγ9Vδ2 T cells were characterized by an increased expression of perforin, granzyme B, and granulysin compared to IL-2-expanded cells. These cytotoxic molecules were not only increased in a resting state, but also released to a greater extent upon target recognition. In contrast, CD107a and cytokine expression did not differ between expansion conditions. However, IL-2/IL-15-expanded Vγ9Vδ2 T cells showed higher levels of transcription factor T-bet expression, which could indicate that T-bet and cytotoxic molecule levels confer the increased cytotoxicity. These results advocate the inclusion of IL-15 into ex vivo Vγ9Vδ2 T cell expansion protocols in future clinical studies.

Ex vivo pulsed dendritic cell vaccination against cancer

As the most powerful antigen-presenting cell type, dendritic cells (DCs) can induce potent antigen-specific immune responses in vivo, hence becoming optimal cell population for vaccination purposes. DCs can be derived ex vivo in quantity and manipulated extensively to be endowed with adequate immune-stimulating capacity. After pulsing with cancer antigens in various ways, the matured DCs are administrated back into the patient. DCs home to lymphoid organs to present antigens to and activate specific lymphocytes that react to a given cancer. Ex vivo pulsed DC vaccines have been vigorously investigated for decades, registering encouraging results in relevant immunotherapeutic clinical trials, while facing some solid challenges. With more details in DC biology understood, new theory proposed, and novel technology introduced (featuring recently emerged mRNA vaccine technology), it is becoming increasingly likely that ex vivo pulsed DC vaccine will fulfill its potential in cancer immunotherapy.

Ex vivo IL-15 replenishment augments bone marrow precursor cell-mediated adaptive immunity via PI3K-Akt pathway

This study tested the hypothesis that PI3K-Akt activity contributes to the superior immune function of IL-15-administrated bone marrow precursor cells (BMPC). Our previous studies revealed that PI3K-Akt play vital role in dendritic cells (DCs) cross-presentation and DC-based CTL priming. Despite the fact that IL-15 serves multiple functions in its therapeutic potential for the induction and maintenance of T cell response, the exact role of PI3K-Akt in IL-15 increased adaptive immunity is still poorly understood. In this study, we demonstrated that ex vivo IL-15 administration increased BMPC capability of antigen uptake and the expression of costimulatory molecules (such as CD80 and 4-1BB(CD137) ligand [4-1BBL]) and MHC class I molecule via PI3K-Akt pathway. Importantly, PI3K-Akt activity was not only necessary for IL-15 augmented BMPC cross-presentation and CTL priming, but also facilitated IL-15 increased therapeutic potential of the cytolytic capacity and maintenance of BMPC-activated T cells. Thus, these data suggested that PI3K-Akt activity contribute to the superior immune function of IL-15-administrated BMPC and thereby might be therapeutic potential for adaptive immunity.

Functional Phenotypes of Human Vγ9Vδ2 T Cells in Lymphoid Stress Surveillance

Butyrophilin and butyrophilin-like proteins select γδ T cells and direct the migration of γδ T cell subsets to distinct anatomical sites. γδ T cells expressing Vδ2 paired with Vγ9 (Vγ9Vδ2 T cells) are the predominant γδ T cell type in human peripheral blood. Vγ9Vδ2 T cells, which cannot be studied easily in vivo because they do not exist in rodents, are often referred to as innate-like T cells. The genetically recombined γδ T cell receptor (TCR) that responds to isoprenoid-derived pyrophosphates (phosphoantigens) produced by infected and malignant cells in a butyrophilin-dependent manner qualifies them as therapeutically relevant components of the adaptive immune system. On the other hand, cell-surface proteins such as the C-type lectin CD161 mark a functional phenotype of Vγ9Vδ2 T cells that mediates TCR-independent innate-like responses. Moreover, CD56 (neural cell adhesion molecule, NCAM) and the G protein-coupled receptor GPR56 define Vγ9Vδ2 T cells with increased cytolytic potential and, like CD161, may also be expressed by dendritic cells, principally facilitating the generation of an innate-like immunological synapse. In this review, we summarise current knowledge of Vγ9Vδ2 T cell functional phenotypes that are critical to lymphoid stress surveillance.

CD56 Homodimerization and Participation in Anti-Tumor Immune Effector Cell Functioning: A Role for Interleukin-15

A particularly interesting marker to identify anti-tumor immune cells is the neural cell adhesion molecule (NCAM), also known as cluster of differentiation (CD)56. Namely, hematopoietic expression of CD56 seems to be confined to powerful effector immune cells. Here, we sought to elucidate its role on various killer immune cells. First, we identified the high motility NCAM-120 molecule to be the main isoform expressed by immune cells. Next, through neutralization of surface CD56, we were able to (1) demonstrate the direct involvement of CD56 in tumor cell lysis exerted by CD56-expressing killer cells, such as natural killer cells, gamma delta (γδ) T cells, and interleukin (IL)-15-cultured dendritic cells (DCs), and (2) reveal a putative crosstalk mechanism between IL-15 DCs and CD8 T cells, suggesting CD56 as a co-stimulatory molecule in their cell-to-cell contact. Moreover, by means of a proximity ligation assay, we visualized the CD56 homophilic interaction among cancer cells and between immune cells and cancer cells. Finally, by blocking the mitogen-activated protein kinase (MAPK) pathway and the phosphoinositide 3-kinase (PI3K)-Akt pathway, we showed that IL-15 stimulation directly led to CD56 upregulation. In conclusion, these results underscore the previously neglected importance of CD56 expression on immune cells, benefiting current and future immune therapeutic options.

γδ T cells: pleiotropic immune effectors with therapeutic potential in cancer

The potential of cancer immunotherapy relies on the mobilization of immune cells capable of producing antitumour cytokines and effectively killing tumour cells. These are major attributes of γδ T cells, a lymphoid lineage that is often underestimated despite its major role in tumour immune surveillance, which has been established in a variety of preclinical cancer models. This situation notwithstanding, in particular instances the tumour microenvironment seemingly mobilizes γδ T cells with immunosuppressive or tumour-promoting functions, thus emphasizing the importance of regulating γδ T cell responses in order to realize their translation into effective cancer immunotherapies. In this Review we outline both seminal work and recent advances in our understanding of how γδ T cells participate in tumour immunity and how their functions are regulated in experimental models of cancer. We also discuss the current strategies aimed at maximizing the therapeutic potential of human γδ T cells, on the eve of their exploration in cancer clinical trials that may position them as key players in cancer immunotherapy.

Innate Immune Cells: A Potential and Promising Cell Population for Treating Osteosarcoma

Advanced, recurrent, or metastasized osteosarcomas remain challenging to cure or even alleviate. Therefore, the development of novel therapeutic strategies is urgently needed. Cancer immunotherapy has greatly improved in recent years, with options including adoptive cellular therapy, vaccination, and checkpoint inhibitors. As such, immunotherapy is becoming a potential strategy for the treatment of osteosarcoma. Innate immunocytes, the first line of defense in the immune system and the bridge to adaptive immunity, are one of the vital effector cell subpopulations in cancer immunotherapy. Innate immune cell-based therapy has shown potent antitumor activity against hematologic malignancies and some solid tumors, including osteosarcoma. Importantly, some immune checkpoints are expressed on both innate and adaptive immune cells, modulating their functions in tumor immunity. Therefore, blocking or activating immune checkpoint-mediated downstream signaling pathways can improve the therapeutic effects of innate immune cell-based therapy. In this review, we summarize the current status and future prospects of innate immune cell-based therapy for the treatment of osteosarcoma, with a focus on the potential synergistic effects of combination therapy involving innate immunotherapy and immune checkpoint inhibitors/oncolytic viruses.

Dendritic Cell-Based Immunotherapy of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a type of blood cancer characterized by the uncontrolled clonal proliferation of myeloid hematopoietic progenitor cells in the bone marrow. The outcome of AML is poor, with five-year overall survival rates of less than 10% for the predominant group of patients older than 65 years. One of the main reasons for this poor outcome is that the majority of AML patients will relapse, even after they have attained complete remission by chemotherapy. Chemotherapy, supplemented with allogeneic hematopoietic stem cell transplantation in patients at high risk of relapse, is still the cornerstone of current AML treatment. Both therapies are, however, associated with significant morbidity and mortality. These observations illustrate the need for more effective and less toxic treatment options, especially in elderly AML and have fostered the development of novel immune-based strategies to treat AML. One of these strategies involves the use of a special type of immune cells, the dendritic cells (DCs). As central orchestrators of the immune system, DCs are key to the induction of anti-leukemia immunity. In this review, we provide an update of the clinical experience that has been obtained so far with this form of immunotherapy in patients with AML.

Human double negative T cells target lung cancer via ligand-dependent mechanisms that can be enhanced by IL-15

Background

The advents of novel immunotherapies have revolutionized the treatment of cancer. Adoptive cellular therapies using chimeric antigen receptor T (CAR-T) cells have achieved remarkable clinical responses in B cell leukemia and lymphoma but the effect on solid tumors including lung cancer is limited. Here we present data on the therapeutic potential of allogeneic CD3⁺CD4⁻CD8⁻ double negative T (DNT) cells as a new cellular therapy for the treatment of lung cancer and underlying mechanisms.

Methods

DNTs were enriched and expanded ex vivo from healthy donors and phenotyped by flow cytometry. Functionally, their cytotoxicity was determined against primary and established non-small-cell lung cancer (NSCLC) cell lines in vitro or through in vivo adoptive transfer into xenograft models. Mechanistic analysis was performed using blocking antibodies against various cell surface and soluble markers. Furthermore, the role of IL-15 on DNT function was determined.

Results

We demonstrated that ex vivo expanded DNTs can effectively lyse various human NSCLC cells in vitro and inhibit tumor growth in xenograft models. Expanded DNTs have a cytotoxic phenotype, as they express NKp30, NKG2D, DNAM-1, membrane TRAIL (mTRAIL), perforin and granzyme B, and secrete IFNγ and soluble TRAIL (sTRAIL). DNT-mediated cytotoxicity was dependent on a combination of tumor-expressed ligands for NKG2D, DNAM-1, NKp30 and/or receptors for TRAIL, which differ among different NSCLC cell lines. Furthermore, stimulation of DNTs with IL-15 increased expression of effector molecules on DNTs, their TRAIL production and cytotoxicity against NSCLC in vitro and in vivo.

Conclusion

Healthy donor-derived DNTs can target NSCLC in vitro and in vivo. DNTs recognize tumors via innate receptors which can be up-regulated by IL-15. DNTs have the potential to be used as a novel adoptive cell therapy for lung cancer either alone or in combination with IL-15.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0507-2) contains supplementary material, which is available to authorized users.

PD-1 signaling modulates interferon-γ production by Gamma Delta (γδ) T-Cells in response to leukemia

Gamma delta (γδ) T-cell based immunotherapy is a promising concept for the treatment of hematologic malignancies. Not only in vitro but also in early phase clinical trials, zoledronic acid (Zol) and interleukin-2 (IL-2) have been successfully used to activate human γδ T-cells and to induce clinical anti-tumor effects. Aiming to improve the effectiveness of future γδ T-cell based immunotherapies against leukemia, we analyzed the impact of programmed cell death protein 1 (PD-1) signaling, on the different phases of γδ T-cell activation, of proliferation, production of anti-tumor cytokines and cytotoxic function in vitro. PD-1 expression was found significantly upregulated between day 2 and day 4 following stimulation with Zol and IL-2. However, proliferation or expression of activation markers of γδ, αβ and NK-cells are not altered by additional PD-1 blockade. Pembrolizumab increases interferon-γ (IFN-γ) production in γδ T-cells upon direct stimulation with Zol and in response to Zol treated primary acute myeloid leukemia (AML) cells by approximately 57% and 30%, respectively. Zol sensitized primary AML cells also induce PD-1 expression in co-cultured γδ T-cells and such PD-1(+) cells contain more IFN-γ. In contrast, PD-1 blockade does not have a significant effect on direct cell dependent lysis of leukemia cells by γδ T-cells. This study demonstrates that PD-1 blockade impacts cell dependent cytotoxicity and cytokine production in response to leukemia cells differently. While Pembrolizumab did not increase cell lysis of stimulated and expanded γδ T-cells, it induces significant upregulation of the potent pro-inflammatory and anti-tumor cytokine IFN-γ, which might facilitate anti-leukemia effects.