IL-15 trans-presentation promotes human NK cell development and differentiation in vivo

Long-term engraftment of human stem and progenitor cells for large-scale production of functional immune cells in engineered pigs

Existing immunodeficient pig models have demonstrated limited success in supporting robust human haematopoietic engraftment and multilineage differentiation. Here we hypothesize that the targeted deletion of integrin-associated protein (Cd47) in severe combined immunodeficient pigs, with deletions in the X-linked interleukin-2 receptor gamma chain and recombination activating gene 1, would enable long-term haematopoietic engraftment following transplantation with human haematopoietic stem/progenitor cells. In Cd47-deficient pigs, we observed high levels of human haematopoietic chimerism in the blood and spleen, with functional T and B lymphocytes, natural killer and myeloid cells, as well as robust thymopoiesis. Our findings suggest that severe combined immunodeficient pigs with Cd47 deletion represent an improved preclinical model for studying human haematopoiesis, disease mechanisms and therapies, and offer potential as a bioreactor for large-scale production of human immune cells.

Facing the Challenge to Mimic Breast Cancer Heterogeneity: Established and Emerging Experimental Preclinical Models Integrated with Omics Technologies

Breast cancer (BC) is among the most common neoplasms globally and is the leading cause of cancer-related mortality in women. Despite significant advancements in prevention, early diagnosis, and treatment strategies made over the past two decades, breast cancer continues to pose a significant global health challenge. One of the major obstacles in the clinical management of breast cancer patients is the high intertumoral and intratumoral heterogeneity that influences disease progression and therapeutic outcomes. The inability of preclinical experimental models to replicate this diversity has hindered the comprehensive understanding of BC pathogenesis and the development of new therapeutic strategies. An ideal experimental model must recapitulate every aspect of human BC to maintain the highest predictive validity. Therefore, a thorough understanding of each model's inherent characteristics and limitations is essential to bridging the gap between basic research and translational medicine. In this context, omics technologies serve as powerful tools for establishing comparisons between experimental models and human tumors, which may help address BC heterogeneity and vulnerabilities. This review examines the BC models currently used in preclinical research, including cell lines, patient-derived organoids (PDOs), organ-on-chip technologies, carcinogen-induced mouse models, genetically engineered mouse models (GEMMs), and xenograft mouse models. We emphasize the advantages and disadvantages of each model and outline the most important applications of omics techniques to aid researchers in selecting the most relevant model to address their specific research questions.

Nanomaterial-Interleukin Combination for Boosting NK Cell-Based Tumor Immunotherapy

The use of natural killer (NK) cell-based immunotherapy has been extensively explored in clinical trials for multiple types of tumors and has surfaced as a promising approach in tumor immunotherapy. Interleukins (ILs), a vital class of cytokines, play a crucial role in regulating several functions of NK cells, thereby becoming a focal point in the advancement of NK cell-based therapies. Nonetheless, the use of ILs as single agents is significantly constrained by their short half-life, limited efficacy, and adverse reactions. Currently, nanomaterials are being progressively employed in the delivery of ILs to enhance NK cell-based immunotherapy. However, there is currently a lack of comprehensive reviews summarizing the design of NK-cell-targeted nanomaterials and related systems for delivery of ILs. Furthermore, certain nanomaterials, either alone or in conjunction with other therapeutics, can also promote the secretion of ILs, representing a promising avenue for further exploration. Accordingly, this review begins by outlining various types of ILs and subsequently discusses the advancements in applying nanomaterials for IL delivery. It also examines the potential of nanomaterials to enhance IL secretion from other immune cells, thereby influencing the NK cell functionality. Lastly, this review addresses the challenges associated with using nanomaterials in these contexts and offers perspectives for future research. This study aims to provide valuable insights into the development of NK cell immunotherapy and innovative nanomaterial-based drug delivery systems.

From ex vivo to in vitro models: towards a novel approach to investigate the efficacy of immunotherapies on exhausted Vγ9Vδ2 T cells?

Human γδ T cells demonstrate remarkable and diverse antitumor properties driven by TCR-dependent activation. Their non-alloreactive nature and pivotal role in cancer immunity position them as attractive targets for immunotherapies. However, upon infiltrating tumors, due to mechanisms induced by the tumor microenvironment's immune evasion strategies, these cells frequently become exhausted, greatly weakening the efficacy and antitumor potential of novel immunotherapeutic treatments. While being extensively characterized in CD8+ T cells, research on γδ T cell exhaustion remains scarce. There is a growing need for comprehensive models to investigate the reinvigoration properties of exhausted γδ T cells. This review synthesizes current strategies and models for evaluating novel immunotherapies aimed at rejuvenating exhausted γδ T cells. It explores a progression of approaches, from ex vivo studies and in vivo murine models to emerging in vitro systems. The advantages and limitations of these models are discussed to provide a comprehensive understanding of their potential in advancing therapeutic research. Furthermore, recent findings suggesting in vitro exhaustion phenotypes closely mirror those observed ex vivo highlight opportunities for preclinical innovation. By refining these models, researchers can better optimize the immunotherapies targeting this unique T cell subset.

Cytokines in Focus: IL-2 and IL-15 in NK Adoptive Cell Cancer Immunotherapy

NK cell adoptive cell therapy (ACT) has emerged as a promising strategy for cancer immunotherapy, offering advantages in scalability, accessibility, efficacy, and safety. Ex vivo activation and expansion protocols, incorporating feeder cells and cytokine cocktails, have enabled the production of highly functional NK cells in clinically relevant quantities. Advances in NK cell engineering, including CRISPR-mediated gene editing and chimeric Ag receptor technologies, have further enhanced cytotoxicity, persistence, and tumor targeting. Cytokine support post-adoptive transfer, particularly with IL-2 and IL-15, remains critical for promoting NK cell survival, proliferation, and anti-tumor activity despite persistent challenges such as regulatory T cell expansion and cytokine-related toxicities. This review explores the evolving roles of IL-2 and IL-15 in NK cell-based ACT, evaluating their potential and limitations, and highlights strategies to optimize these cytokines for effective cancer immunotherapy.

Vitamin D stimulates Il-15 synthesis in rodent muscle

Besides its classical skeletal function, vitamin D plays a critical role in both skeletal muscle and the immune system. Interleukin-15 (IL-15), which is highly expressed, and secreted complexed with its receptor, IL-15Rα, by skeletal muscle, stimulates the development of immune cells and affects myogenesis and muscle mass. However, little is known about possible regulators of this myokine. To test whether vitamin D could be a regulator of muscle IL-15 and IL-15Rα expression, C2C12 myotubes were treated with vitamin D3 metabolites and analysis were performed in gastrocnemius muscles of rats treated with a single intraperitoneal dose of 1,25(OH)2D3. The role of VDR was investigated by siRNA technique in C2C12 myotubes and in gastrocnemius muscles of vitamin D receptor knockout (Vdr-KO) mice. Treatment of C2C12 myotubes with 1,25(OH)2D3 or 25(OH)D3 increased Il-15 gene expression in a dose-dependent manner and 1,25(OH)2D3 also moderately increased the relative Il-15 protein amount. Rats treated with a single dose of 1,25(OH)2D3 demonstrated a higher mRNA abundance of muscle Il-15 than controls. The 1,25(OH)2D3 effect on Il-15 was considerably weaker in C2C12 myotubes treated with Vdr-specific siRNA. Vdr-KO mice showed significantly lower muscle Il-15 mRNA than WT mice. Il-15Ra mRNA and Il-15/Il-15Rα protein abundance were unaffected by 1,25(OH)2D3-treatment or VDR functionality, and Cyp27b1 activity is not required for 25(OH)D3-mediated Il-15 gene expression. The results provide evidence for a regulatory role of hydroxyvitamin D3 metabolites on the Il-15 synthesis in skeletal muscle cells, which is largely mediated by the VDR.

Nanrilkefusp alfa (SOT101), an IL-15 receptor βγ superagonist, as a single agent or with anti-PD-1 in patients with advanced cancers

Nanrilkefusp alfa (nanril; SOT101) is an interleukin (IL)-15 receptor βγ superagonist that stimulates natural killer (NK) and CD8+ T cells, thereby promoting an innate and adaptive anti-tumor inflammatory microenvironment in mouse tumor models either in monotherapy or combined with an anti-programmed cell death protein 1 (PD-1) antibody. In cynomolgus monkeys, a clinical schedule was identified, which translated into the design of a phase 1/1b clinical trial, AURELIO-03 (NCT04234113). In 51 patients with advanced/metastatic solid tumors, nanril increased the proportions of CD8+ T cells and NK cells in peripheral blood and tumors. It had a favorable safety profile when administered subcutaneously on days 1, 2, 8, and 9 of each 21-day cycle as monotherapy (0.25-15 μg/kg) or combined (1.5-12 μg/kg) with the anti-PD-1 pembrolizumab (200 mg). The most frequent treatment-emergent adverse events were pyrexia, injection site reactions, and chills. Furthermore, early clinical efficacy was observed, including in immune checkpoint blockade-resistant/refractory patients.

Bulk and single-cell transcriptomics identify gene signatures of stem cell-derived NK cell donors with superior cytolytic activity

Allogeneic natural killer (NK) cell therapies are a valuable treatment option for cancer, given their remarkable safety and favorable efficacy profile. Although the use of allogeneic donors allows for off-the-shelf and timely patient treatment, intrinsic interindividual differences put clinical efficacy at risk. The identification of donors with superior anti-tumor activity is essential to ensure the success of adoptive NK cell therapies. Here, we investigated the heterogeneity of 10 umbilical cord blood stem cell-derived NK cell batches. First, we evaluated the donors' cytotoxic potential against tumor cell lines from solid and hematological cancer indications, to distinguish a group of superior, "excellent" killers (4/10), compared with "good" killers (6/10). Next, bulk and single-cell RNA sequencing, performed at different stages of NK differentiation, revealed distinct transcriptomic features of the two groups. Excellent donors showed an enrichment in cytotoxicity pathways and a depletion of myeloid traits, linked to the presence of a larger population of effector-like NK cells early on during differentiation. Consequently, we defined a multi-factorial gene expression signature able to predict the donors' cytotoxic potential. Our study contributes to the identification of key traits of superior NK cell batches, supporting the development of efficacious NK therapeutics and the achievement of durable anti-tumor responses.

NK cell receptors in anti-tumor and healthy tissue protection: Mechanisms and therapeutic advances

Natural Killer (NK) cells are integral to the innate immune system, renowned for their ability to target and eliminate cancer cells without the need for antigen presentation, sparing normal tissues. These cells are crucial in cancer immunosurveillance due to their diverse array of activating and inhibitory receptors that modulate their cytotoxic activity. However, the tumor microenvironment can suppress NK cell function through various mechanisms. Over recent decades, research has focused on overcoming these tumor escape mechanisms. Initially, efforts concentrated on enhancing T cell activity, leading to impressive results with immunotherapeutic approaches aimed at boosting T cell responses. Nevertheless, a substantial number of patients do not benefit from these treatments and continue to seek effective alternatives. In this context, NK cells present a promising avenue for developing new treatments, given their potent cytotoxic capabilities, safety profile, and activity against T cell-resistant tumors, such as those lacking HLA-I expression. Recent advancements in immunotherapy include strategies to restore and amplify NK cell activity through immune checkpoint inhibitors, cytokines, adoptive NK cell therapy, and CAR-NK cell technology. This review provides a comprehensive overview of NK cell receptors, the tumor escape mechanisms that hinder NK cell function, and the evolving field of NK cell-based cancer immunotherapy, highlighting ongoing efforts to develop more effective and targeted cancer treatment strategies.

Advances in Induced Pluripotent Stem Cell-Derived Natural Killer Cell Therapy

Natural killer (NK) cells are cytotoxic lymphocytes of the innate immune system capable of killing virus-infected cells and/or cancer cells. The commonly used NK cells for therapeutic applications include primary NK cells and immortalized NK cell lines. However, primary NK cell therapy faces limitations due to its restricted proliferation capacity and challenges in stable storage. Meanwhile, the immortalized NK-92 cell line requires irradiation prior to infusion, which reduces its cytotoxic activity, providing a ready-made alternative and overcoming these bottlenecks. Recent improvements in differentiation protocols for iPSC-derived NK cells have facilitated the clinical production of iPSC-NK cells. Moreover, iPSC-NK cells can be genetically modified to enhance tumor targeting and improve the expansion and persistence of iPSC-NK cells, thereby achieving more robust antitumor efficacy. This paper focuses on the differentiation-protocols efforts of iPSC-derived NK cells and the latest progress in iPSC-NK cell therapy. Additionally, we discuss the current challenges faced by iPSC-NK cells and provide an outlook on future applications and developments.

Differential Effector Function of Tissue-Specific Natural Killer Cells against Lung Tumors

INTRODUCTION

Natural killer (NK) cells are innate lymphoid cells capable of directly killing target cells while modulating immune effector responses. Despite their multifunctional capacities, a limited understanding of their plasticity and heterogeneity has impeded progress in developing effective NK cell-based cancer therapies. In this study, we investigated NK cell tissue heterogeneity in relation to their phenotype and effector functions against lung tumors.

METHODS

Using hanging drop tumor spheroid and subcutaneously established LL/2 (LLC1) lung tumor models, we examined NK cell receptor diversity and its correlation with tissue-specific cytotoxicity through multiparametric flow cytometry, fluorescence imaging, and cytotoxicity assays.

RESULTS

We identified distinct patterns of cell surface receptors expression on tissue-specific NK cells that are crucial for antitumor activity. Linear regression mathematical analyses further revealed significant positive correlations between activation-associated cell surface receptors and cytotoxic capacity in NK cells from tissues such as the liver and bone marrow.

CONCLUSION

These findings underscore the differential effector capacities of NK cells from distinct tissues, even prior to exposure to LL/2 tumor cells. This highlights the significance of tissue-specific NK cell heterogeneity and its impact on their antitumor cytotoxicity. Recognizing these distinct tissue-specific receptor expression patterns will be instrumental in developing more efficacious NK cell-based cancer treatments.

Pathophysiology and preclinical relevance of experimental graft-versus-host disease in humanized mice

Graft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantations (allo-HCT) used for the treatment of hematological malignancies and other blood-related disorders. Until recently, the discovery of actionable molecular targets to treat GVHD and their preclinical testing was almost exclusively based on modeling allo-HCT in mice by transplanting bone marrow and splenocytes from donor mice into MHC-mismatched recipient animals. However, due to fundamental differences between human and mouse immunology, the translation of these molecular targets into the clinic can be limited. Therefore, humanized mouse models of GVHD were developed to circumvent this limitation. In these models, following the transplantation of human peripheral blood mononuclear cells (PBMCs) into immunodeficient mice, T cells recognize and attack mouse organs, inducing GVHD. Thereby, humanized mice provide a platform for the evaluation of the effects of candidate therapies on GVHD mediated by human immune cells in vivo. Understanding the pathophysiology of this xenogeneic GVHD is therefore crucial for the design and interpretation of experiments performed with this model. In this article, we comprehensively review the cellular and molecular mechanisms governing GVHD in the most commonly used model of xenogeneic GVHD: PBMC-engrafted NOD/LtSz-PrkdcscidIL2rγtm1Wjl (NSG) mice. By re-analyzing public sequencing data, we also show that the clonal expansion and the transcriptional program of T cells in humanized mice closely reflect those in humans. Finally, we highlight the strengths and limitations of this model, as well as arguments in favor of its biological relevance for studying T-cell reactions against healthy tissues or cancer cells.

Single-cell RNA sequencing reveals anti-tumor potency of CD56+ NK cells and CD8+ T cells in humanized mice via PD-1 and TIGIT co-targeting

In solid tumors, the exhaustion of natural killer (NK) cells and cytotoxic T cells in the immunosuppressive tumor microenvironment poses challenges for effective tumor control. Conventional humanized mouse models of hepatocellular carcinoma patient-derived xenografts (HCC-PDX) encounter limitations in NK cell infiltration, hindering studies on NK cell immunobiology. Here, we introduce an improved humanized mouse model with restored NK cell reconstitution and infiltration in HCC-PDX, coupled with single-cell RNA sequencing (scRNA-seq) to identify potential anti-HCC treatments. A single administration of adeno-associated virus carrying human interleukin-15 reinstated persistent NK cell reconstitution and infiltration in HCC-PDX in humanized mice. scRNA-seq revealed NK cell and T cell subpopulations with heightened PDCD1 and TIGIT levels. Notably, combination therapy with anti-PD-1 and anti-TIGIT antibodies alleviated HCC burden in humanized mice, demonstrating NK cell-dependent efficacy. Bulk-RNA sequencing analysis also revealed significant alterations in the tumor transcriptome that may contribute to further resistance after combination therapy, warranting further investigations. As an emerging strategy, ongoing clinical trials with anti-PD-1 and anti-TIGIT antibodies provide limited data. The improved humanized mouse HCC-PDX model not only sheds light on the pivotal role of NK cells but also serves as a robust platform for evaluating safety and anti-tumor efficacy of combination therapies and other potential regimens, complementing clinical insights.

Development of a humanized mouse model with functional human materno-fetal interface immunity

Materno-fetal immunity possesses specialized characteristics to ensure pathogen clearance while maintaining tolerance to the semiallogeneic fetus. Most of our understanding on human materno-fetal immunity is based on conventional rodent models that may not precisely represent human immunological processes owing to the huge evolutionary divergence. Herein, we developed a pregnant human immune system (HIS) mouse model through busulfan preconditioning, which hosts multilineage human immune subset reconstitution at the materno-fetal interface. Human materno-fetal immunity exhibits a tolerogenic feature at the midgestation stage (embryonic day [E] 14.5), and human immune regulatory subsets were detected in the decidua. However, the immune system switches to an inflammatory profile at the late gestation stage (E19). A cell-cell interaction network contributing to the alternations in the human materno-fetal immune atmosphere was revealed based on single-cell RNA-Seq analysis, wherein human macrophages played crucial roles by secreting several immune regulatory mediators. Furthermore, depletion of Treg cells at E2.5 and E5.5 resulted in severe inflammation and fetus rejection. Collectively, these results demonstrate that the pregnant HIS mouse model permits the development of functional human materno-fetal immunity and offers a tool for human materno-fetal immunity investigation to facilitate drug discovery for reproductive disorders.

cellPLATO - an unsupervised method for identifying cell behaviour in heterogeneous cell trajectory data

Advances in imaging, segmentation and tracking have led to the routine generation of large and complex microscopy datasets. New tools are required to process this 'phenomics' type data. Here, we present 'Cell PLasticity Analysis Tool' (cellPLATO), a Python-based analysis software designed for measurement and classification of cell behaviours based on clustering features of cell morphology and motility. Used after segmentation and tracking, the tool extracts features from each cell per timepoint, using them to segregate cells into dimensionally reduced behavioural subtypes. Resultant cell tracks describe a 'behavioural ID' at each timepoint, and similarity analysis allows the grouping of behavioural sequences into discrete trajectories with assigned IDs. Here, we use cellPLATO to investigate the role of IL-15 in modulating human natural killer (NK) cell migration on ICAM-1 or VCAM-1. We find eight behavioural subsets of NK cells based on their shape and migration dynamics between single timepoints, and four trajectories based on sequences of these behaviours over time. Therefore, by using cellPLATO, we show that IL-15 increases plasticity between cell migration behaviours and that different integrin ligands induce different forms of NK cell migration.

IL15RA-STAT3-GPX4/ACSL3 signaling leads to ferroptosis resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant disease with a poor prognosis, and the lack of effective treatment methods accounts for its high mortality. Pancreatic stellate cells (PSCs) in the tumor microenvironment play an important role in the development of PDAC. Previous studies have reported that patients with PDAC are more vulnerable to ferroptosis inducers. To investigate the relationship between PSCs and pancreatic cancer cells, a coculture system is used to further reveal the influence of PSCs on ferroptosis resistance in PDAC using many in vitro and in vivo experiments. Our results show that PSCs promote ferroptosis resistance in pancreatic cancer cells. We further demonstrate that IL15 secretion by PSCs activates the IL15RA-STAT3-GPX4/ACSL3 axis. The simultaneous upregulation of GPX4 and ACSL3 prevents lipid peroxidation and ultimately protects pancreatic cancer cells from ferroptosis both in vitro and in vivo. This study demonstrates that PSCs protect pancreatic cancer cells in a paracrine manner and may indicate a novel strategy for the treatment of PDAC.

Immunosuppressant therapy averts rejection of allogeneic FKBP1A-disrupted CAR-T cells

Chimeric antigen receptor (CAR) T cells from allogeneic donors promise "off-the-shelf" availability by overcoming challenges associated with autologous cell manufacturing. However, recipient immunologic rejection of allogeneic CAR-T cells may decrease their in vivo lifespan and limit treatment efficacy. Here, we demonstrate that the immunosuppressants rapamycin and tacrolimus effectively mitigate allorejection of HLA-mismatched CAR-T cells in immunocompetent humanized mice, extending their in vivo persistence to that of syngeneic humanized mouse-derived CAR-T cells. In turn, genetic knockout (KO) of FKBP prolyl isomerase 1A (FKBP1A), which encodes a protein targeted by both drugs, was necessary to confer CD19-specific CAR-T cells (19CAR) robust functional resistance to these immunosuppressants. FKBP1AKO 19CAR-T cells maintained potent in vitro functional profiles and controlled in vivo tumor progression similarly to untreated 19CAR-T cells. Moreover, immunosuppressant treatment averted in vivo allorejection permitting FKBP1AKO 19CAR-T cell-driven B cell aplasia. Thus, we demonstrate that genome engineering enables immunosuppressant treatment to improve the therapeutic potential of universal donor-derived CAR-T cells.

Systemic dysregulation and molecular insights into poor influenza vaccine response in the aging population

Vaccination-induced protection against influenza is greatly diminished and increasingly heterogeneous with age. We investigated longitudinally (up to five time points) a cohort of 234 vaccinated >65-year-old vaccinees with adjuvanted vaccine FluAd across two independent seasons. System-level analyses of multiomics datasets measuring six modalities and serological data revealed that poor responders lacked time-dependent changes in response to vaccination as observed in responders, suggestive of systemic dysregulation in poor responders. Multiomics integration revealed key molecules and their likely role in vaccination response. High prevaccination plasma interleukin-15 (IL-15) concentrations negatively associated with antibody production, further supported by experimental validation in mice revealing an IL-15-driven natural killer cell axis explaining the suppressive role in vaccine-induced antibody production as observed in poor responders. We propose a subset of long-chain fatty acids as modulators of persistent inflammation in poor responders. Our findings provide a potential link between low-grade chronic inflammation and poor vaccination response and open avenues for possible pharmacological interventions to enhance vaccine responses.

Efficient generation of human NOTCH ligand-expressing haemogenic endothelial cells as infrastructure for in vitro haematopoiesis and lymphopoiesis

Arterial endothelial cells (AECs) are the founder cells for intraembryonic haematopoiesis. Here, we report a method for the efficient generation of human haemogenic DLL4+ AECs from pluripotent stem cells (PSC). Time-series single-cell RNA-sequencing reveals the dynamic evolution of haematopoiesis and lymphopoiesis, generating cell types with counterparts present in early human embryos, including stages marked by the pre-haematopoietic stem cell genes MECOM/EVI1, MLLT3 and SPINK2. DLL4+ AECs robustly support lymphoid differentiation, without the requirement for exogenous NOTCH ligands. Using this system, we find IL7 acts as a morphogenic factor determining the fate choice between the T and innate lymphoid lineages and also plays a role in regulating the relative expression level of RAG1. Moreover, we document a developmental pathway by which human RAG1+ lymphoid precursors give rise to the natural killer cell lineage. Our study describes an efficient method for producing lymphoid progenitors, providing insights into their endothelial and haematopoietic ontogeny, and establishing a platform to investigate the development of the human blood system.

The Role of Natural Killer Cells in Oncolytic Virotherapy: Friends or Foes?

Oncolytic virotherapy (OVT) has emerged as a promising cancer immunotherapy, and is capable of potentiating other immunotherapies due to its capacity to increase tumor immunogenicity and to boost host antitumor immunity. Natural killer (NK) cells are a critical cellular component for mediating the antitumor response, but hold a mixed reputation for their role in mediating the therapeutic efficacy of OVT. This review will discuss the pros and cons of how NK cells impact OVT, and how to harness this knowledge for the development of effective strategies that could modulate NK cells to improve OVT-based therapeutic outcomes.

Neuroinflammation in Alzheimer's disease: insights from peripheral immune cells

Alzheimer's disease (AD) is a serious brain disorder characterized by the presence of beta-amyloid plaques, tau pathology, inflammation, neurodegeneration, and cerebrovascular dysfunction. The presence of chronic neuroinflammation, breaches in the blood-brain barrier (BBB), and increased levels of inflammatory mediators are central to the pathogenesis of AD. These factors promote the penetration of immune cells into the brain, potentially exacerbating clinical symptoms and neuronal death in AD patients. While microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in AD, recent evidence suggests the infiltration of cerebral vessels and parenchyma by peripheral immune cells, including neutrophils, T lymphocytes, B lymphocytes, NK cells, and monocytes in AD. These cells participate in the regulation of immunity and inflammation, which is expected to play a huge role in future immunotherapy. Given the crucial role of peripheral immune cells in AD, this article seeks to offer a comprehensive overview of their contributions to neuroinflammation in the disease. Understanding the role of these cells in the neuroinflammatory response is vital for developing new diagnostic markers and therapeutic targets to enhance the diagnosis and treatment of AD patients.

Facts and Hopes on Chimeric Cytokine Agents for Cancer Immunotherapy

Cytokines are key mediators of immune responses that can modulate the antitumor activity of immune cells. Cytokines have been explored as a promising cancer immunotherapy. However, there are several challenges to cytokine therapy, especially a lack of tumor targeting, resulting in high toxicity and limited efficacy. To overcome these limitations, novel approaches have been developed to engineer cytokines with improved properties, such as chimeric cytokines. Chimeric cytokines are fusion proteins that combine different cytokine domains or link cytokines to antibodies (immunocytokines) or other molecules that can target specific receptors or cells. Chimeric cytokines can enhance the selectivity and stability of cytokines, leading to reduced toxicity and improved efficacy. In this review, we focus on two promising cytokines, IL2 and IL15, and summarize the current advances and challenges of chimeric cytokine design and application for cancer immunotherapy. Most of the current approaches focus on increasing the potency of cytokines, but another important goal is to reduce toxicity. Cytokine engineering is promising for cancer immunotherapy as it can enhance tumor targeting while minimizing adverse effects.

No time to die: Epigenetic regulation of natural killer cell survival

NK cells are short-lived innate lymphocytes that can mediate antigen-independent responses to infection and cancer. However, studies from the past two decades have shown that NK cells can acquire transcriptional and epigenetic modifications during inflammation that result in increased survival and lifespan. These findings blur the lines between the innate and adaptive arms of the immune system, and suggest that the homeostatic mechanisms that govern the persistence of innate immune cells are malleable. Indeed, recent studies have shown that NK cells undergo continuous and strictly regulated adaptations controlling their survival during development, tissue residency, and following inflammation. In this review, we summarize our current understanding of the critical factors regulating NK cell survival throughout their lifespan, with a specific emphasis on the epigenetic modifications that regulate the survival of NK cells in various contexts. A precise understanding of the molecular mechanisms that govern NK cell survival will be important to enhance therapies for cancer and infectious diseases.

Retinoic acid receptor activation reprograms senescence response and enhances anti-tumor activity of natural killer cells

Cellular senescence can exert dual effects in tumors, either suppressing or promoting tumor progression. The senescence-associated secretory phenotype (SASP), released by senescent cells, plays a crucial role in this dichotomy. Consequently, the clinical challenge lies in developing therapies that safely enhance senescence in cancer, favoring tumor-suppressive SASP factors over tumor-promoting ones. Here, we identify the retinoic-acid-receptor (RAR) agonist adapalene as an effective pro-senescence compound in prostate cancer (PCa). Reactivation of RARs triggers a robust senescence response and a tumor-suppressive SASP. In preclinical mouse models of PCa, the combination of adapalene and docetaxel promotes a tumor-suppressive SASP that enhances natural killer (NK) cell-mediated tumor clearance more effectively than either agent alone. This approach increases the efficacy of the allogenic infusion of human NK cells in mice injected with human PCa cells, suggesting an alternative therapeutic strategy to stimulate the anti-tumor immune response in "immunologically cold" tumors.

B cell development and antibody responses in human immune system mice: current status and future perspective

Humanized immune system (HIS) mice have been developed and used as a small surrogate model to study human immune function under normal or disease conditions. Although variations are found between models, most HIS mice show robust human T cell responses. However, there has been unsuccessful in constructing HIS mice that produce high-affinity human antibodies, primarily due to defects in terminal B cell differentiation, antibody affinity maturation, and development of primary follicles and germinal centers. In this review, we elaborate on the current knowledge about and previous attempts to improve human B cell development in HIS mice, and propose a potential strategy for constructing HIS mice with improved humoral immunity by transplantation of human follicular dendritic cells (FDCs) to facilitate the development of secondary follicles.

Efbalropendekin Alfa enhances human natural killer cell cytotoxicity against tumor cell lines in vitro

IL-15 has shown preclinical activity by enhancing the functional maturation of natural killer (NK) cells. Clinical evaluation of the potential anticancer activity of most cytokines, including IL-15, has been limited by low tolerability and rapid in vivo clearance. Efbalropendekin Alfa (XmAb24306) is a soluble IL15/IL15-receptor alpha heterodimer complex fused to a half-life extended Fc domain (IL15/IL15Rα-Fc), engineered with mutations to reduce IL-15 affinity for CD122. Reduced affinity drives lower potency, leading to prolonged pharmacodynamic response in cynomolgus monkeys. We show that in vitro, human NK cells treated with XmAb24306 demonstrate enhanced cytotoxicity against various tumor cell lines. XmAb24306-treated NK cells also exhibit enhanced killing of 3D colorectal cancer spheroids. Daratumumab (dara), a monoclonal antibody (mAb) that targets CD38 results in antibody-dependent cellular cytotoxicity (ADCC) of both multiple myeloma (MM) cells and NK cells. Addition of XmAb24306 increases dara-mediated NK cell ADCC against various MM cell lines in vitro. Because NK cells express CD38, XmAb24306 increases dara-mediated NK cell fratricide, but overall does not negatively impact the ADCC activity against a MM cell line likely due to increased NK cell activity of the surviving cells. These data show that XmAb24306 increases direct and ADCC-mediated human NK cell cytotoxicity in vitro.

Combined therapy of CAR-IL-15/IL-15Rα-T cells and GLIPR1 knockdown in cancer cells enhanced anti-tumor effect against gastric cancer

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapy has shown remarkable responses in hematological malignancies with several approved products, but not in solid tumors. Patients suffer from limited response and tumor relapse due to low efficacy of CAR-T cells in the complicated and immunosuppressive tumor microenvironment. This clinical challenge has called for better CAR designs and combined strategies to improve CAR-T cell therapy against tumor changes.

METHODS

In this study, IL-15/IL-15Rα was inserted into the extracellular region of CAR targeting mesothelin. In-vitro cytotoxicity and cytokine production were detected by bioluminescence-based killing and ELISA respectively. In-vivo xenograft mice model was used to evaluate the anti-tumor effect of CAR-T cells. RNA-sequencing and online database analysis were used to identify new targets in residual gastric cancer cells after cytotoxicity assay. CAR-T cell functions were detected in vitro and in vivo after GLI Pathogenesis Related 1 (GLIPR1) knockdown in gastric cancer cells. Cell proliferation and migration of gastric cancer cells were detected by CCK-8 and scratch assay respectively after GLIPR1 were overexpressed or down-regulated.

RESULTS

CAR-T cells constructed with IL-15/IL-15Rα (CAR-ss-T) showed significantly improved CAR-T cell expansion, cytokine production and cytotoxicity, and resulted in superior tumor control compared to conventional CAR-T cells in gastric cancer. GLIPR1 was up-regulated after CAR-T treatment and survival was decreased in gastric cancer patients with high GLIPR1 expression. Overexpression of GLIPR1 inhibited cytotoxicity of conventional CAR-T but not CAR-ss-T cells. CAR-T treatment combined with GLIPR1 knockdown increased anti-tumor efficacy in vitro and in vivo.

CONCLUSIONS

Our data demonstrated for the first time that this CAR structure design combined with GLIPR1 knockdown in gastric cancer improved CAR-T cell-mediated anti-tumor response.

Development of a prognostic signature for immune-associated genes in bladder cancer and exploring potential drug findings

BACKGROUND

Bladder cancer, predominantly affecting men, is a prevalent malignancy of the urinary system. Although platinum-based chemotherapy has demonstrated certain enhancements in overall survival when compared to surgery alone, the efficacy of treatments is impeded by the unfavorable side effects of conventional chemotherapy medications. Nonetheless, immunotherapy exhibits potential in the treatment of bladder cancer.

METHODS

To create an immune-associated prognostic signature for bladder cancer, bioinformatics analyses were performed utilizing The Cancer Genome Atlas (TCGA) database in this study. By identifying differential gene expressions between the high-risk and low-risk groups, a potential therapeutic drug was predicted using the Connectivity Map database. Subsequently, the impact of this drug on the growth of T24 cells was validated through MTT assay and 3D cell culture techniques.

RESULTS

The signature included 1 immune-associated LncRNA (NR2F1-AS1) and 16 immune-associated mRNAs (DEFB133, RBP7, PDGFRA, CGB3, PDGFD, SCG2, ADCYAP1R1, OPRL1, PGR, PSMD1, TANK, PRDX1, ADIPOR2, S100A8, AHNAK, EGFR). Based on the assessment of risk scores, the patients were classified into cohorts of low-risk and high-risk individuals. The cohort with low risk demonstrated a considerably higher likelihood of survival in comparison to the group with high risk. Furthermore, variations in immune infiltration were noted among the two categories. Cephaeline, a possible medication, was discovered by analyzing variations in gene expression. It exhibited promise in suppressing the viability and growth of T24 bladder cancer cells.

CONCLUSION

The novel predictive pattern allows for efficient categorization of patients with bladder cancer, enabling focused and rigorous treatment for those expected to have a worse prognosis. The discovery of a possible curative medication establishes a basis for forthcoming immunotherapy trials in bladder cancer.

Signalling mechanisms driving homeostatic and inflammatory effects of interleukin-15 on tissue lymphocytes

There is an intriguing dichotomy in the function of cytokine interleukin-15-at low levels, it is required for the homeostasis of the immune system, yet when it is upregulated in response to pathogenic infections or in autoimmunity, IL-15 drives inflammation. IL-15 associates with the IL-15Rα within both myeloid and non-haematopoietic cells, where IL-15Rα trans-presents IL-15 in a membrane-bound form to neighboring cells. Alongside homeostatic maintenance of select lymphocyte populations such as NK cells and tissue-resident T cells, when upregulated, IL-15 also promotes inflammatory outcomes by driving effector function and cytotoxicity in NK cells and T cells. As chronic over-expression of IL-15 can lead to autoimmunity, IL-15 expression is tightly regulated. Thus, blocking dysregulated IL-15 and its downstream signalling pathways are avenues for immunotherapy. In this review we discuss the molecular pathways involved in IL-15 signalling and how these pathways contribute to both homeostatic and inflammatory functions in IL-15-dependent mature lymphoid populations, focusing on innate, and innate-like lymphocytes in tissues.

CD45 limits early Natural Killer cell development

The clinical development of Natural Killer (NK) cell-mediated immunotherapy marks a milestone in the development of new cancer therapies and has gained traction due to the intrinsic ability of the NK cell to target and kill tumor cells. To fully harness the tumor killing ability of NK cells, we need to improve NK cell persistence and to overcome suppression of NK cell activation in the tumor microenvironment. The trans-membrane, protein tyrosine phosphatase CD45, regulates NK cell homeostasis, with the genetic loss of CD45 in mice resulting in increased numbers of mature NK cells. This suggests that CD45-deficient NK cells might display enhanced persistence following adoptive transfer. However, we demonstrate here that adoptive transfer of CD45-deficiency did not enhance NK cell persistence in mice, and instead, the homeostatic disturbance of NK cells in CD45-deficient mice stemmed from a developmental defect in the progenitor population. The enhanced maturation within the CD45-deficient NK cell compartment was intrinsic to the NK cell lineage, and independent of the developmental defect. CD45 is not a conventional immune checkpoint candidate, as systemic loss is detrimental to T and B cell development, compromising the adaptive immune system. Nonetheless, this study suggests that inhibition of CD45 in progenitor or stem cell populations may improve the yield of in vitro generated NK cells for adoptive therapy.

CD8+ lymphocytes are critical for early control of tuberculosis in macaques

The functional role of CD8+ lymphocytes in tuberculosis remains poorly understood. We depleted innate and/or adaptive CD8+ lymphocytes in macaques and showed that loss of all CD8α+ cells (using anti-CD8α antibody) significantly impaired early control of Mycobacterium tuberculosis (Mtb) infection, leading to increased granulomas, lung inflammation, and bacterial burden. Analysis of barcoded Mtb from infected macaques demonstrated that depletion of all CD8+ lymphocytes allowed increased establishment of Mtb in lungs and dissemination within lungs and to lymph nodes, while depletion of only adaptive CD8+ T cells (with anti-CD8β antibody) worsened bacterial control in lymph nodes. Flow cytometry and single-cell RNA sequencing revealed polyfunctional cytotoxic CD8+ lymphocytes in control granulomas, while CD8-depleted animals were unexpectedly enriched in CD4 and γδ T cells adopting incomplete cytotoxic signatures. Ligand-receptor analyses identified IL-15 signaling in granulomas as a driver of cytotoxic T cells. These data support that CD8+ lymphocytes are required for early protection against Mtb and suggest polyfunctional cytotoxic responses as a vaccine target.

NK Cell Therapeutics for Hematologic Malignancies: from Potential to Fruition

PURPOSE OF REVIEW

The current review focuses on the preclinical development and clinical advances of natural killer (NK) cell therapeutics for hematologic malignancies and offers perspective on the unmet challenges that will direct future discovery in the field.

RECENT FINDINGS

Approaches to improve or re-direct NK cell anti-tumor functions against hematologic malignancies have included transgenic expression of chimeric antigen receptors (CARs), administration of NK cell engagers including BiKEs and TriKEs that enhance antibody-dependent cellular cytotoxicity (ADCC) by co-engaging NK cell CD16 and antigens on tumors, incorporation of a non-cleavable CD16 that results in enhanced ADCC, use of induced memory-like NK cells alone or in combination with CARs, and blockade of NK immune checkpoints to enhance NK cytotoxicity. Recently reported and ongoing clinical trials support the feasibility and safety of these approaches. NK cell-based therapeutic strategies hold great promise as cost-effective, off-the-shelf cell therapies for patients with relapsed and refractory hematologic diseases.

A human immune system (HIS) mouse model that dissociates roles for mouse and human FcR+ cells during antibody-mediated immune responses

Human immune system (HIS) mice provide a model to study human immune responses in vivo. Currently available HIS mouse models may harbor mouse Fc Receptor (FcR)-expressing cells that exert potent effector functions following administration of human Ig. Previous studies showed that the ablation of the murine FcR gamma chain (FcR-γ) results in loss of antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis in vivo. We created a new FcR-γ-deficient HIS mouse model to compare host (mouse) versus graft (human) effects underlying antibody-mediated immune responses in vivo. FcR-γ-deficient HIS recipients lack expression and function of mouse activating FcRs and can be stably and robustly reconstituted with human immune cells. By screening blood B-cell depletion by rituximab Ig variants, we found that human FcγRs-mediated IgG1 effects, whereas mouse activating FcγRs were dominant in IgG4 effects. Complement played a role as an IgG1 variant (IgG1 K322A) lacking complement binding activity was largely ineffective. Finally, we provide evidence that FcγRIIIA on human NK cells could mediate complement-independent B-cell depletion by IgG1 K322A. We anticipate that our FcR-γ-deficient HIS model will help clarify mechanisms of action of exogenous administered human antibodies in vivo.

M-CSF directs myeloid and NK cell differentiation to protect from CMV after hematopoietic cell transplantation

Therapies reconstituting autologous antiviral immunocompetence may represent an important prophylaxis and treatment for immunosuppressed individuals. Following hematopoietic cell transplantation (HCT), patients are susceptible to Herpesviridae including cytomegalovirus (CMV). We show in a murine model of HCT that macrophage colony-stimulating factor (M-CSF) promoted rapid antiviral activity and protection from viremia caused by murine CMV. M-CSF given at transplantation stimulated sequential myeloid and natural killer (NK) cell differentiation culminating in increased NK cell numbers, production of granzyme B and interferon-γ. This depended upon M-CSF-induced myelopoiesis leading to IL15Rα-mediated presentation of IL-15 on monocytes, augmented by type I interferons from plasmacytoid dendritic cells. Demonstrating relevance to human HCT, M-CSF induced myelomonocytic IL15Rα expression and numbers of functional NK cells in G-CSF-mobilized hematopoietic stem and progenitor cells. Together, M-CSF-induced myelopoiesis triggered an integrated differentiation of myeloid and NK cells to protect HCT recipients from CMV. Thus, our results identify a rationale for the therapeutic use of M-CSF to rapidly reconstitute antiviral activity in immunocompromised individuals, which may provide a general paradigm to boost innate antiviral immunocompetence using host-directed therapies.

cellPLATO: an unsupervised method for identifying cell behaviour in heterogeneous cell trajectory data

Advances in imaging, cell segmentation, and cell tracking now routinely produce microscopy datasets of a size and complexity comparable to transcriptomics or proteomics. New tools are required to process this 'phenomics' type data. Cell PLasticity Analysis TOol (cellPLATO) is a Python-based analysis software designed for measurement and classification of diverse cell behaviours based on clustering of parameters of cell morphology and motility. cellPLATO is used after segmentation and tracking of cells from live cell microscopy data. The tool extracts morphological and motility metrics from each cell per timepoint, before being using them to segregate cells into behavioural subtypes with dimensionality reduction. Resultant cell tracks have a 'behavioural ID' for each cell per timepoint corresponding to their changing behaviour over time in a sequence. Similarity analysis allows the grouping of behavioural sequences into discrete trajectories with assigned IDs. Trajectories and underlying behaviours generate a phenotypic fingerprint for each experimental condition, and representative cells are mathematically identified and graphically displayed for human understanding of each subtype. Here, we use cellPLATO to investigate the role of IL-15 in modulating NK cell migration on ICAM-1 or VCAM-1. We find 8 behavioural subsets of NK cells based on their shape and migration dynamics, and 4 trajectories of behaviour. Therefore, using cellPLATO we show that IL-15 increases plasticity between cell migration behaviours and that different integrin ligands induce different forms of NK cell migration.

Increased ILT2+ natural killer T cells correlate with disease activity in systemic lupus erythematosus

OBJECTIVE

Numerous immune cell types, such as B and T lymphocytes, natural killer cells (NK), and NKT cells, are related to the pathogenesis of diseases in systemic lupus erythematosus (SLE). Our goal in this investigation is to examine the phenotype of NK cells and NKT cells alterations in individuals with SLE.

METHODS

Typically, 50 SLE patients and 24 age-matched healthy people had their PBMCs obtained. Employing flow cytometry, the phenotype of NK and NKT cells and immunoglobulin-like transcript 2 (ILT2) expressions were identified. ELISA was utilized to evaluate the amounts of interleukin-15 (IL-15) and sHLA-G in the serum.

RESULTS

The frequencies of the circulating NK and NKT cells in individuals with SLE were decreased compared to healthy controls. Furthermore, ILT2 expression was significantly increased in NKT cells, but showed no obvious change in NK cells. Clinical severity and active nephritis were substantially associated with ILT2+ NKT cell frequencies. The correlation study showed that the upregulation of ILT2 expression was related to sHLA-G in plasma but not to IL-15.

CONCLUSIONS

ILT2+ NKT cells have a vital function in the immune abnormalities of SLE, which can also supply a viable goal for therapeutic intervention. Key Points •ILT2 expression was significantly increased in NKT cells in SLE patients. •ILT2+ NKT cell frequencies were associated with clinical severity which may be used as an indicator for evaluating disease activity in patients with SLE.

Deciphering the localization and trajectory of human natural killer cell development

Innate immune cells represent the first line of cellular immunity, comprised of both circulating and tissue-resident natural killer cells and innate lymphoid cells. These innate lymphocytes arise from a common CD34+ progenitor that differentiates into mature natural killer cells and innate lymphoid cells. The successive stages in natural killer cell maturation are characterized by increased lineage restriction and changes to phenotype and function. Mechanisms of human natural killer cell development have not been fully elucidated, especially the role of signals that drive the spatial localization and maturation of natural killer cells. Cytokines, extracellular matrix components, and chemokines provide maturation signals and influence the trafficking of natural killer cell progenitors to peripheral sites of differentiation. Here we present the latest advances in our understanding of natural killer and innate lymphoid cell development in peripheral sites, including secondary lymphoid tissues (i.e. tonsil). Recent work in the field has provided a model for the spatial distribution of natural killer cell and innate lymphoid cell developmental intermediates in tissue and generated further insights into the developmental niche. In support of this model, future studies using multifaceted approaches seek to fully map the developmental trajectory of human natural killer cells and innate lymphoid cells in secondary lymphoid tissues.

NK cell subsets and dysfunction during viral infection: a new avenue for therapeutics?

In the setting of viral challenge, natural killer (NK) cells play an important role as an early immune responder against infection. During this response, significant changes in the NK cell population occur, particularly in terms of their frequency, location, and subtype prevalence. In this review, changes in the NK cell repertoire associated with several pathogenic viral infections are summarized, with a particular focus placed on changes that contribute to NK cell dysregulation in these settings. This dysregulation, in turn, can contribute to host pathology either by causing NK cells to be hyperresponsive or hyporesponsive. Hyperresponsive NK cells mediate significant host cell death and contribute to generating a hyperinflammatory environment. Hyporesponsive NK cell populations shift toward exhaustion and often fail to limit viral pathogenesis, possibly enabling viral persistence. Several emerging therapeutic approaches aimed at addressing NK cell dysregulation have arisen in the last three decades in the setting of cancer and may prove to hold promise in treating viral diseases. However, the application of such therapeutics to treat viral infections remains critically underexplored. This review briefly explores several therapeutic approaches, including the administration of TGF-β inhibitors, immune checkpoint inhibitors, adoptive NK cell therapies, CAR NK cells, and NK cell engagers among other therapeutics.

Graded expression of the chemokine receptor CX3CR1 marks differentiation states of human and murine T cells and enables cross-species interpretation

T cells differentiate into functionally distinct states upon antigen encounter. These states are delineated by different cell surface markers for murine and human T cells, which hamper cross-species translation of T cell properties. We aimed to identify surface markers that reflect the graded nature of CD8+ T cell differentiation and delineate functionally comparable states in mice and humans. CITEseq analyses revealed that graded expression of CX3CR1, encoding the chemokine receptor CX3CR1, correlated with the CD8+ T cell differentiation gradient. CX3CR1 expression distinguished human and murine CD8+ and CD4+ T cell states, as defined by migratory and functional properties. Graded CX3CR1 expression, refined with CD62L, accurately captured the high-dimensional T cell differentiation continuum. Furthermore, the CX3CR1 expression gradient delineated states with comparable properties in humans and mice in steady state and on longitudinally tracked virus-specific CD8+ T cells in both species. Thus, graded CX3CR1 expression provides a strategy to translate the behavior of distinct T cell differentiation states across species.

Current Advances in Humanized Mouse Models for Studying NK Cells and HIV Infection

Human immunodeficiency virus (HIV) has infected millions of people worldwide and continues to be a major global health problem. Scientists required a small animal model to study HIV pathogenesis and immune responses. To this end, humanized mice were created by transplanting human cells and/or tissues into immunodeficient mice to reconstitute a human immune system. Thus, humanized mice have become a critical animal model for HIV researchers, but with some limitations. Current conventional humanized mice are prone to death by graft versus host disease induced by the mouse signal regulatory protein α and CD47 signaling pathway. In addition, commonly used humanized mice generate low levels of human cytokines required for robust myeloid and natural killer cell development and function. Here, we describe recent advances in humanization procedures and transgenic and knock-in immunodeficient mice to address these limitations.

Mouse Models for HTLV-1 Infection and Adult T Cell Leukemia

Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice. Each mouse model has different characteristics that must be considered before use for different HTLV-1 research purposes. HTLV-1 Tax and HBZ transgenic mice spontaneously develop tumors, and the roles of both Tax and HBZ in cell transformation and tumor growth have been established. Severely immunodeficient mice were able to be engrafted with ATL cell lines and have been used in preclinical studies of candidate molecules for the treatment of ATL. HTLV-1-infected humanized mice with an established human immune system are a suitable model to characterize cells in the early stages of HTLV-1 infection. This review outlines the characteristics of mouse models of HTLV-1 infection/ATL and describes progress made in elucidating the pathogenesis of ATL and developing related therapies using these mice.

Unwinding the Role of the CMG Helicase in Inborn Errors of Immunity

Inborn errors of immunity (IEI) are a collection of diseases resulting from genetic causes that impact the immune system through multiple mechanisms. Natural killer cell deficiency (NKD) is one such IEI where natural killer (NK) cells are the main immune lineage affected. Though rare, the deficiency of several genes has been described as underlying causes of NKD, including MCM4, GINS1, MCM10 , and GINS4 , all of which are involved in the eukaryotic CMG helicase. The CMG helicase is made up of C DC45 – M CM – G INS and accessory proteins including MCM10. The CMG helicase plays a critical role in DNA replication by unwinding the double helix and enabling access of polymerases to single-stranded DNA, and thus helicase proteins are active in any proliferating cell. Replication stress, DNA damage, and cell cycle arrest are among the cellular phenotypes attributed to loss of function variants in CMG helicase proteins. Despite the ubiquitous function of the CMG helicase, NK cells have an apparent susceptibility to the deficiency of helicase proteins. This review will examine the role of the CMG helicase in inborn errors of immunity through the lens of NKD and further discuss why natural killer cells can be so strongly affected by helicase deficiency.

Research progress of interleukin-15 in cancer immunotherapy

Interleukin-15 (IL-15) is a cytokine that belongs to the interleukin-2 (IL-2) family and is essential for the development, proliferation, and activation of immune cells, including natural killer (NK) cells, T cells and B cells. Recent studies have revealed that interleukin-15 also plays a critical role in cancer immunotherapy. Interleukin-15 agonist molecules have shown that interleukin-15 agonists are effective in inhibiting tumor growth and preventing metastasis, and some are undergoing clinical trials. In this review, we will summarize the recent progress in interleukin-15 research over the past 5 years, highlighting its potential applications in cancer immunotherapy and the progress of interleukin-15 agonist development.

Simultaneous targeting of PD-1 and IL-2Rβγ with radiation therapy inhibits pancreatic cancer growth and metastasis

In pancreatic ductal adenocarcinoma (PDAC) patients, we show that response to radiation therapy (RT) is characterized by increased IL-2Rβ and IL-2Rγ along with decreased IL-2Rα expression. The bispecific PD1-IL2v is a PD-1-targeted IL-2 variant (IL-2v) immunocytokine with engineered IL-2 cis targeted to PD-1 and abolished IL-2Rα binding, which enhances tumor-antigen-specific T cell activation while reducing regulatory T cell (Treg) suppression. Using PD1-IL2v in orthotopic PDAC KPC-driven tumor models, we show marked improvement in local and metastatic survival, along with a profound increase in tumor-infiltrating CD8+ T cell subsets with a transcriptionally and metabolically active phenotype and preferential activation of antigen-specific CD8+ T cells. In combination with single-dose RT, PD1-IL2v treatment results in a robust, durable expansion of polyfunctional CD8+ T cells, T cell stemness, tumor-specific memory immune response, natural killer (NK) cell activation, and decreased Tregs. These data show that PD1-IL2v leads to profound local and distant response in PDAC.

Nasal administration of recombinant Neospora caninum secreting IL-15/IL-15Rα inhibits metastatic melanoma development in lung

BACKGROUND

Metastases are the leading cause of mortality in many cancer types and lungs are one of the most common sites of metastasis alongside the liver, brain, and bones. In melanoma, 85% of late-stage patients harbor lung metastases. A local administration could enhance the targeting of metastases while limiting the systemic cytotoxicity. Therefore, intranasal administration of immunotherapeutic agents seems to be a promising approach to preferentially target lung metastases and decrease their burden on cancer mortality. From observations that certain microorganisms induce an acute infection of the tumor microenvironment leading to a local reactivating immune response, microbial-mediated immunotherapy is a next-generation field of investigation in which immunotherapies are engineered to overcome immune surveillance and escape from microenvironmental cancer defenses.

METHODS

The goal of our study is to evaluate the potential of the intranasal administration of Neospora caninum in a syngeneic C57BL6 mouse model of B16F10 melanoma lung metastases. It also compares the antitumoral properties of a wild-type N. caninum versus N. caninum secreting human interleukin (IL)-15 fused to the sushi domain of the IL-15 receptor α chain, a potent activator of cellular immune responses.

RESULTS

The treatment of murine lung metastases by intranasal administration of an N. caninum engineered to secrete human IL-15 impairs lung metastases from further progression with only 0,08% of lung surface harboring metastases versus 4,4% in wild-type N. caninum treated mice and 36% in untreated mice. The control of tumor development is associated with a strong increase in numbers, within the lung, of natural killer cells, CD8⁺ T cells and macrophages, up to twofold, fivefold and sixfold, respectively. Analysis of expression levels of CD86 and CD206 on macrophages surface revealed a polarization of these macrophages towards an antitumoral M1 phenotype.

CONCLUSION

Administration of IL-15/IL-15Rα-secreting N. caninum through intranasal administration, a non-invasive route, lend further support to N. caninum-demonstrated clear potential as an effective and safe immunotherapeutic approach for the treatment of metastatic solid cancers, whose existing therapeutic options are scarce. Combination of this armed protozoa with an intranasal route could reinforce the existing therapeutic arsenal against cancer and narrow the spectrum of incurable cancers.

Lymphoid cell development from fetal hematopoietic progenitors and human pluripotent stem cells

Lymphoid cells encompass the adaptive immune system, including T and B cells and Natural killer T cells (NKT), and innate immune cells (ILCs), including Natural Killer (NK) cells. During adult life, these lineages are thought to derive from the differentiation of long-term hematopoietic stem cells (HSCs) residing in the bone marrow. However, during embryogenesis and fetal development, the ontogeny of lymphoid cells is both complex and multifaceted, with a large body of evidence suggesting that lymphoid lineages arise from progenitor cell populations antedating the emergence of HSCs. Recently, the application of single cell RNA-sequencing technologies and pluripotent stem cell-based developmental models has provided new insights into lymphoid ontogeny during embryogenesis. Indeed, PSC differentiation platforms have enabled de novo generation of lymphoid immune cells independently of HSCs, supporting conclusions drawn from the study of hematopoiesis in vivo. Here, we examine lymphoid development from non-HSC progenitor cells and technological advances in the differentiation of human lymphoid cells from pluripotent stem cells for clinical translation.

Establishment of humanized mice and its application progress in cancer immunotherapy

The current high prevalence of malignant tumors has attracted considerable attention, and treating advanced malignancies is becoming increasingly difficult. Although immunotherapy is a hopeful alternative, it is effective in only a few people. Thus, development of preclinical animal models is needed. Humanized xenotransplantation mouse models can help with selecting treatment protocols, evaluating curative effects and assessing prognosis. This review discusses the establishment of humanized mouse models and their application prospects in cancer immunotherapy to identify tailored therapies for individual patients.

Humanized mouse models with endogenously developed human natural killer cells for in vivo immunogenicity testing of HLA class I-edited iPSC-derived cells

Human induced pluripotent stem cells (hiPSCs) genetically depleted of human leucocyte antigen (HLA) class I expression can bypass T cell alloimmunity and thus serve as a one-for-all source for cell therapies. However, these same therapies may elicit rejection by natural killer (NK) cells, since HLA class I molecules serve as inhibitory ligands of NK cells. Here, we focused on testing the capacity of endogenously developed human NK cells in humanized mice (hu-mice) using MTSRG and NSG-SGM3 strains to assay the tolerance of HLA-edited iPSC-derived cells. High NK cell reconstitution was achieved with the engraftment of cord blood-derived human hematopoietic stem cells (hHSCs) followed by the administration of human interleukin-15 (hIL-15) and IL-15 receptor alpha (hIL-15Rα). Such "hu-NK mice" rejected HLA class I-null hiPSC-derived hematopoietic progenitor cells (HPCs), megakaryocytes and T cells, but not HLA-A/B-knockout, HLA-C expressing HPCs. To our knowledge, this study is the first to recapitulate the potent endogenous NK cell response to non-tumor HLA class I-downregulated cells in vivo. Our hu-NK mouse models are suitable for the non-clinical evaluation of HLA-edited cells and will contribute to the development of universal off-the-shelf regenerative medicine.

Patient-derived xenograft models in cancer therapy: technologies and applications

Patient-derived xenograft (PDX) models, in which tumor tissues from patients are implanted into immunocompromised or humanized mice, have shown superiority in recapitulating the characteristics of cancer, such as the spatial structure of cancer and the intratumor heterogeneity of cancer. Moreover, PDX models retain the genomic features of patients across different stages, subtypes, and diversified treatment backgrounds. Optimized PDX engraftment procedures and modern technologies such as multi-omics and deep learning have enabled a more comprehensive depiction of the PDX molecular landscape and boosted the utilization of PDX models. These irreplaceable advantages make PDX models an ideal choice in cancer treatment studies, such as preclinical trials of novel drugs, validating novel drug combinations, screening drug-sensitive patients, and exploring drug resistance mechanisms. In this review, we gave an overview of the history of PDX models and the process of PDX model establishment. Subsequently, the review presents the strengths and weaknesses of PDX models and highlights the integration of novel technologies in PDX model research. Finally, we delineated the broad application of PDX models in chemotherapy, targeted therapy, immunotherapy, and other novel therapies.

Next-generation humanized NSG-SGM3 mice are highly susceptible to Staphylococcus aureus infection

Humanized hemato-lymphoid system mice, or humanized mice, emerged in recent years as a promising model to study the course of infection of human-adapted or human-specific pathogens. Though Staphylococcus aureus infects and colonizes a variety of species, it has nonetheless become one of the most successful human pathogens of our time with a wide armory of human-adapted virulence factors. Humanized mice showed increased vulnerability to S. aureus compared to wild type mice in a variety of clinically relevant disease models. Most of these studies employed humanized NSG (NOD-scid IL2Rgnull) mice which are widely used in the scientific community, but show poor human myeloid cell reconstitution. Since this immune cell compartment plays a decisive role in the defense of the human immune system against S. aureus, we asked whether next-generation humanized mice, like NSG-SGM3 (NOD-scid IL2Rgnull-3/GM/SF) with improved myeloid reconstitution, would prove to be more resistant to infection. To our surprise, we found the contrary when we infected humanized NSG-SGM3 (huSGM3) mice with S. aureus: although they had stronger human immune cell engraftment than humanized NSG mice, particularly in the myeloid compartment, they displayed even more pronounced vulnerability to S. aureus infection. HuSGM3 mice had overall higher numbers of human T cells, B cells, neutrophils and monocytes in the blood and the spleen. This was accompanied by elevated levels of pro-inflammatory human cytokines in the blood of huSGM3 mice. We further identified that the impaired survival of huSGM3 mice was not linked to higher bacterial burden nor to differences in the murine immune cell repertoire. Conversely, we could demonstrate a correlation of the rate of humanization and the severity of infection. Collectively, this study suggests a detrimental effect of the human immune system in humanized mice upon encounter with S. aureus which might help to guide future therapy approaches and analysis of virulence mechanisms.