Multiple levels of chemokine receptor regulation in the control of mouse natural killer cell development

Deletion of the mRNA endonuclease Regnase-1 promotes NK cell anti-tumor activity via OCT2-dependent transcription of Ifng

Limited infiltration and activity of natural killer (NK) and T cells within the tumor microenvironment (TME) correlate with poor immunotherapy responses. Here, we examined the role of the endonuclease Regnase-1 on NK cell anti-tumor activity. NK cell-specific deletion of Regnase-1 (Reg1ΔNK) augmented cytolytic activity and interferon-gamma (IFN-γ) production in vitro and increased intra-tumoral accumulation of Reg1ΔNK-NK cells in vivo, reducing tumor growth dependent on IFN-γ. Transcriptional changes in Reg1ΔNK-NK cells included elevated IFN-γ expression, cytolytic effectors, and the chemokine receptor CXCR6. IFN-γ induced expression of the CXCR6 ligand CXCL16 on myeloid cells, promoting further recruitment of Reg1ΔNK-NK cells. Mechanistically, Regnase-1 deletion increased its targets, the transcriptional regulators OCT2 and IκBζ, following interleukin (IL)-12 and IL-18 stimulation, and the resulting OCT2-IκBζ-NF-κB complex induced Ifng transcription. Silencing Regnase-1 in human NK cells increased the expression of IFNG and POU2F2. Our findings highlight NK cell dysfunction in the TME and propose that targeting Regnase-1 could augment active NK cell persistence for cancer immunotherapy.

The Immunological Mechanisms and Immune-Based Biomarkers of Drug-Induced Liver Injury

Drug-induced liver injury (DILI) has become one of the major challenges of drug safety all over the word. So far, about 1,100 commonly used drugs including the medications used regularly, herbal and/or dietary supplements, have been reported to induce liver injury. Moreover, DILI is the main cause of the interruption of new drugs development and drugs withdrawn from the pharmaceutical market. Acute DILI may evolve into chronic DILI or even worse, commonly lead to life-threatening acute liver failure in Western countries. It is generally considered to have a close relationship to genetic factors, environmental risk factors, and host immunity, through the drug itself or its metabolites, leading to a series of cellular events, such as haptenization and immune response activation. Despite many researches on DILI, the specific biomarkers about it are not applicable to clinical diagnosis, which still relies on the exclusion of other causes of liver disease in clinical practice as before. Additionally, circumstantial evidence has suggested that DILI is mediated by the immune system. Here, we review the underlying mechanisms of the immune response to DILI and provide guidance for the future development of biomarkers for the early detection, prediction, and diagnosis of DILI.

NK cell and ILC heterogeneity in colorectal cancer. New perspectives from high dimensional data

Innate lymphoid cells (ILCs) and tissue-resident natural killer (NK) cells ensure immunity at environmental interfaces and help maintain barrier integrity of the intestinal tract. This wide range of innate lymphocytes is able to provide fast and potent inflammatory responses that, when deregulated, have been associated with pathogenesis of inflammatory bowel disease (IBD) and colorectal cancer (CRC). While the presence of tumor-infiltrating NK cells is generally associated with a favorable outcome in CRC patients, emerging evidence reveals distinct roles for ILCs in regulating CRC pathogenesis and progression. Advances in next generation sequencing technology, and in particular of single-cell RNA-seq approaches, along with multidimensional flow cytometry analysis, have helped to deconvolute the complexity and heterogeneity of the ILC system both in homeostatic and pathological contexts. In this review, we discuss the protective and detrimental roles of NK cells and ILCs in the pathogenesis of CRC, focusing on the phenotypic and transcriptional modifications these cells undergo during CRC development and progression.

Natural Killer Cell Homing and Persistence in the Bone Marrow After Adoptive Immunotherapy Correlates With Better Leukemia Control

Cellular immunotherapy using allogeneic natural killer (NK) cells may overcome chemotherapy-refractory acute myeloid leukemia. Our goal was to document NK cell homing/persistence in the bone marrow following adoptive immunotherapy. Our cohort included 109 patients who received NK cell therapy for refractory acute myeloid leukemia following lymphodepleting conditioning +/- denileukin diftitox, +/- low-dose total body irradiation. We evaluated the NK cell density in bone marrow core biopsies performed an average of 14 days after NK cell transfer using a CD56 immunohistochemical stain. The NK cell density in core biopsies showed only moderate correlation with NK cell percentage in bone marrow aspirates evaluated by flow cytometry (rs=0.48) suggesting that distribution of CD56 cells in the bone marrow niche offers unique insight into NK cell homing. Better leukemia control was associated with increased NK cell density, such that patients with <5% blasts had a higher NK cell density (P=0.01). As well, NK cell density above the median of reference group was significantly associated with morphologic remission of leukemia (P=0.01). Moreover, the NK cell density varied significantly between conditioning protocols. Our findings suggest that the use of low-dose irradiation or CD25-targeting immunocytokine (denileukin diftitox, IL2DT) as part of conditioning results in increased NK cell homing/persistence in the bone marrow. These novel results will help guide future immunotherapy with NK cells.

Transcriptional regulation of natural killer cell development and maturation

Natural killer cells are lymphocytes that respond rapidly to intracellular pathogens or cancer/stressed cells by producing pro-inflammatory cytokines or chemokines and by killing target cells through direct cytolysis. NK cells are distinct from B and T lymphocytes in that they become activated through a series of broadly expressed germ line encoded activating and inhibitory receptors or through the actions of inflammatory cytokines. They are the founding member of the innate lymphoid cell family, which mirror the functions of T lymphocytes, with NK cells being the innate counterpart to CD8 T lymphocytes. Despite the functional relationship between NK cells and CD8 T cells, the mechanisms controlling their specification, differentiation and maturation are distinct, with NK cells emerging from multipotent lymphoid progenitors in the bone marrow under the control of a unique transcriptional program. Over the past few years, substantial progress has been made in understanding the developmental pathways and the factors involved in generating mature and functional NK cells. NK cells have immense therapeutic potential and understanding how to acquire large numbers of functional cells and how to endow them with potent activity to control hematopoietic and non-hematopoietic malignancies and autoimmunity is a major clinical goal. In this review, we examine basic aspects of conventional NK cell development in mice and humans and discuss multiple transcription factors that are known to guide the development of these cells.

Natural killer cells are pivotal for in vivo protection following systemic infection by Sporothrix schenckii

Natural killer (NK) cells are one of the first cell types to enter inflammation sites and have been historically known as key effector cells against tumours and viruses; now, accumulating evidence shows that NK cells are also capable of direct in vitro activity and play a protective role against clinically important fungi in vivo. However, our understanding of NK cell development, maturation and activation in the setting of fungal infections is preliminary at best. Sporotrichosis is an emerging worldwide-distributed subcutaneous mycosis endemic in many countries, affecting humans and other animals and caused by various related thermodimorphic Sporothrix species, whose prototypical member is Sporothrix schenckii. We show that following systemic infection of BALB/c mice with S. schenckii sensu stricto, NK cells displayed a more mature phenotype as early as 5 days post-infection as judged by CD11b/CD27 expression. At 10 days post-infection, NK cells had increased expression of CD62 ligand (CD62L) and killer cell lectin-like receptor subfamily G member 1 (KLRG1), but not of CD25 or CD69. Depletion of NK cells with anti-asialo GM1 drastically impaired fungal clearance, leading to a more than eightfold increase in splenic fungal load accompanied by heightened systemic inflammation, as shown by augmented production of the pro-inflammatory cytokines tumour necrosis factor-α, interferon-γ and interleukin-6, but not interleukin-17A, in the spleen and serum. Our study is, to the best of our knowledge, the first to demonstrate that a fungal infection can drive NK cell maturation in vivo and that such cells are pivotal for in vivo protection against S. schenckii.

Non-Cell Autonomous Effects of the Senescence-Associated Secretory Phenotype in Cancer Therapy

In addition to promoting various forms of cell death, most conventional anti-tumor therapies also promote senescence. There is now extensive evidence that therapy-induced senescence (TIS) might be transient, raising the concern that TIS could represent an undesirable outcome of therapy by providing a mechanism for tumor dormancy and eventual disease recurrence. The senescence-associated secretory phenotype (SASP) is a hallmark of TIS and may contribute to aberrant effects of cancer therapy. Here, we propose that the SASP may also serve as a major driver of escape from senescence and the re-emergence of proliferating tumor cells, wherein factors secreted from the senescent cells contribute to the restoration of tumor growth in a non-cell autonomous fashion. Accordingly, anti-SASP therapies might serve to mitigate the deleterious outcomes of TIS. In addition to providing an overview of the putative actions of the SASP, we discuss recent efforts to identify and eliminate senescent tumor cells.

Immune cells in liver regeneration

After partial hepatectomy, hepatocytes proliferate to restore mass and function of the liver. Macrophages, natural killer (NK) cells, natural killer T (NKT) cells, dendritic cells (DC), eosinophils, gamma delta T (γδT) cells, and conventional T cells, as well as other subsets of the immune cells residing in the liver control liver regeneration, either through direct interactions with hepatocytes or indirectly by releasing inflammatory cytokines. Here, we review recent progress regarding the immune cells in the liver and their functions during liver regeneration.

Monocyte/Macrophage: NK Cell Cooperation-Old Tools for New Functions

Monocyte/macrophage and natural killer (NK) cells are partners from a phylogenetic standpoint of innate immune system development and its evolutionary progressive interaction with adaptive immunity. The equally conservative ways of development and differentiation of both invertebrate hemocytes and vertebrate macrophages are reviewed. Evolutionary conserved molecules occurring in macrophage receptors and effectors have been inherited by vertebrates after their common ancestor with invertebrates. Cytolytic functions of mammalian NK cells, which are rooted in immune cells of invertebrates, although certain NK cell receptors (NKRs) are mammalian new events, are characterized. Broad heterogeneity of macrophage and NK cell phenotypes that depends on surrounding microenvironment conditions and expression profiles of specific receptors and activation mechanisms of both cell types are discussed. The particular tissue specificity of macrophages and NK cells, as well as their plasticity and mechanisms of their polarization to different functional subtypes have been underlined. The chapter summarized studies revealing the specific molecular mechanisms and regulation of NK cells and macrophages that enable their highly specific cross-cooperation. Attention is given to the evolving role of human monocyte/macrophage and NK cell interaction in pathogenesis of hypersensitivity reaction-based disorders, including autoimmunity, as well as in cancer surveillance and progression.

Interleukin-12 bypasses common gamma-chain signalling in emergency natural killer cell lymphopoiesis

Differentiation and homeostasis of natural killer (NK) cells relies on common gamma-chain (γc)-dependent cytokines, in particular IL-15. Consequently, NK cells do not develop in mice with targeted γc deletion. Herein we identify an alternative pathway of NK-cell development driven by the proinflammatory cytokine IL-12, which can occur independently of γc-signalling. In response to viral infection or upon exogenous administration, IL-12 is sufficient to elicit the emergence of a population of CD122+CD49b+ cells by targeting NK-cell precursors (NKPs) in the bone marrow (BM). We confirm the NK-cell identity of these cells by transcriptome-wide analyses and their ability to eliminate tumour cells. Rather than using the conventional pathway of NK-cell development, IL-12-driven CD122+CD49b+ cells remain confined to a NK1.1lowNKp46low stage, but differentiate into NK1.1+NKp46+ cells in the presence of γc-cytokines. Our data reveal an IL-12-driven hard-wired pathway of emergency NK-cell lymphopoiesis bypassing steady-state γc-signalling.

NK Cell-Specific Gata3 Ablation Identifies the Maturation Program Required for Bone Marrow Exit and Control of Proliferation

NK cells are innate lymphocytes capable of eliciting an innate immune response to pathogens. NK cells develop and become mature in the bone marrow (BM) before they migrate out to peripheral organs. Although the developmental program leading to mature NK cells has been studied in the context of several transcription factors, the stage-specific role of GATA3 in NK cell development has been incompletely understood. Using NKp46-Cre-Gata3(fl/fl) mice in which Gata3 deficiency was induced as early as the immature stage of NK cell differentiation, we demonstrated that GATA3 is required for the NK cell maturation beyond the CD27 single-positive stage and is indispensable for the maintenance of liver-resident NK cells. The frequencies of NK cells from NKp46-Cre-Gata3(fl/fl) mice were found higher in the BM but lower in peripheral organs compared with control littermates, indicating that GATA3 controls the maturation program required for BM egress. Despite the defect in maturation, upon murine CMV infection, NK cells from NKp46-Cre-Gata3(fl/fl) mice expanded vigorously, achieving NK cell frequencies surpassing those in controls and therefore provided comparable protection. The heightened proliferation of NK cells from NKp46-Cre-Gata3(fl/fl) mice was cell intrinsic and associated with enhanced upregulation of CD25 expression. Taken together, our results demonstrate that GATA3 is a critical regulator for NK cell terminal maturation and egress out of the BM and that immature NK cells present in the periphery of NKp46-Cre-Gata3(fl/fl) mice can rapidly expand and provide a reservoir of NK cells capable of mounting an efficient cytotoxic response upon virus infection.

NKG2D ligand overexpression in lupus nephritis correlates with increased NK cell activity and differentiation in kidneys but not in the periphery

NK cells are a major component of the immune system, and alterations in their activity are correlated with various autoimmune diseases. In the present work, we observed an increased expression of the NKG2D ligand MICA in SLE patients' kidneys but not healthy subjects. We also show glomerulus-specific expression of the NKG2D ligands Rae-1 and Mult-1 in various murine SLE models, which correlated with a higher number of glomerular-infiltrating NK cells. As the role of NK cells in the immunopathogenesis of SLE is poorly understood, we explored NK cell differentiation and activity in tissues and organs in SLE-prone murine models by use of diseased and prediseased MRL/MpJ and MRL/lpr mice. We report here that phenotypically iNK cells accumulate only in the spleen but not in BM or kidneys of diseased mice. Infiltrating NK cells in kidneys undergoing a lupus nephritic process showed a more mature, activated phenotype compared with kidney, as well as peripheral NK cells from prediseased mice, as determined by IFN-γ and STAT5 analysis. These findings and the presence of glomerulus-specific NKG2D ligands in lupus-prone mice identify a role for NK cells and NKG2D ligands in the lupus nephritic process, which could aid in understanding their role in human SLE.