Development of human natural killer cells and other innate lymphoid cells

Prognostic biomarker HIF1α and its correlation with immune infiltration in gliomas

Certain glioma subtypes, such as glioblastoma multiforme or low-grade glioma, are common malignant intracranial tumors with high rates of relapse and malignant progression even after standard therapy. The overall survival (OS) is poor in patients with gliomas; hence, effective prognostic prediction is crucial. Herein, the present study aimed to explore the potential role of hypoxia-inducible factor 1 subunit alpha (HIF1α) in gliomas and investigate the association between HIF1α and infiltrating immune cells in gliomas. Data from The Cancer Genome Atlas were evaluated via RNA sequencing, clinicopathological, immunological checkpoint, immune infiltration and functional enrichment analyses. Validation of protein abundance was performed using paraffin-embedded samples from patients with glioma. A nomogram model was created to forecast the OS rates at 1, 3 and 5 years after cancer diagnosis. The association between OS and HIF1α expression was estimated using Kaplan-Meier survival analysis and the log-rank test. Finally, HIF1α expression was validated using western blotting, reverse transcription-quantitative PCR, Cell Counting Kit-8 and Transwell assays. The results demonstrated that HIF1α expression was significantly upregulated in gliomas compared with normal human brain glial cells. Immunohistochemistry staining demonstrated differential expression of the HIF1α protein. Moreover, glioma cell viability and migration were inhibited via HIF1α downregulation. HIF1α impacted DNA replication, cell cycling, DNA repair and the immune microenvironment in glioma. HIF1α expression was also positively associated with several types of immune cells and immunological checkpoints and with neutrophils, plasmacytoid dendritic cells and CD56bright cells. The Kaplan-Meier survival analyses further demonstrated a strong association between high HIF1α expression and poor prognosis in patients with glioma. Analysis of the receiver operating characteristic curves demonstrated that HIF1α expression accurately differentiated paired normal brain cells from tumor tissues. Collectively, these findings suggested the potential for HIF1α to be used as a novel prognostic indicator for patients with glioma and that OS prediction models may help in the future to develop effective follow-up and treatment strategies for these patients.

Innate lymphoid cells (ILCs) in teleosts against data on ILCs in humans

It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research.

Systemic immune response in young and elderly patients after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a leading cause of death and long-term disability worldwide. In addition to primary brain damage, systemic immune alterations occur, with evidence for dysregulated immune responses in aggravating TBI outcome and complications. However, immune dysfunction following TBI has been only partially understood, especially in the elderly who represent a substantial proportion of TBI patients and worst outcome. Therefore, we aimed to conduct an in-depth immunological characterization of TBI patients, by evaluating both adaptive (T and B lymphocytes) and innate (NK and monocytes) immune cells of peripheral blood mononuclear cells (PBMC) collected acutely (< 48 h) after TBI in young (18-45 yo) and elderly (> 65 yo) patients, compared to age-matched controls, and also the levels of inflammatory biomarkers.

RESULTS

Our data show that young respond differently than elderly to TBI, highlighting the immune unfavourable status of elderly compared to young patients. While in young only CD4 T lymphocytes are activated by TBI, in elderly both CD4 and CD8 T cells are affected, and are induced to differentiate into subtypes with low cytotoxic activity, such as central memory CD4 T cells and memory precursor effector CD8 T cells. Moreover, TBI enhances the frequency of subsets that have not been previously investigated in TBI, namely the double negative CD27- IgD- and CD38-CD24- B lymphocytes, and CD56dim CD16- NK cells, both in young and elderly patients. TBI reduces the production of pro-inflammatory cytokines TNF-α and IL-6, and the expression of HLA-DM, HLA-DR, CD86/B7-2 in monocytes, suggesting a compromised ability to drive a pro-inflammatory response and to efficiently act as antigen presenting cells.

CONCLUSIONS

We described the acute immunological response induced by TBI and its relation with injury severity, which could contribute to pathologic evolution and possibly outcome. The focus on age-related immunological differences could help design specific therapeutic interventions based on patients' characteristics.

Pan-HDAC inhibitors augment IL2-induced proliferation of NK cells via the JAK2-STAT5B signaling pathway

BACKGROUND

Natural killer (NK) cells are a subtype of lymphocytes with the ability to quickly and efficiently identify and eliminate tumor cells. In the presence of IL2, NK cells can divide rapidly but in limited numbers. According to previous studies, in vivo treatment with histone deacetylase (HDAC) inhibitors did not impair NK-cell function. This study aimed to investigate the effect of HDAC inhibitors on NK-cell proliferation and the underlying regulatory mechanism.

METHODS

NK92 cells, primary NK (pNK) cells, and CD19-CAR-NK92 cells were treated with low concentrations of pan-HDACi Dacinostat (Dac) and Panobinostat (Pan) in the presence of IL2, and Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays were used to assess cell proliferation and apoptosis. The expression of granzyme B was detected by immunofluorescence, and the expression of CD107a and NKG2D was determined by flow cytometry. The downstream regulatory genes were identified by RNA-seq, and the "JAK-STAT signaling pathway"- and "Cell cycle signaling pathway"-related genes were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The JAK2^V617F mouse model was constructed to simulate the upregulation of the JAK2 signaling pathway in vivo, and the NK proliferation was evaluated by flow cytometry. A tumor-bearing nude mouse model was constructed to determine the anti-tumor efficacy of NK92 cells following Dac treatment.

RESULTS

In the presence of IL2, the proliferation rate of NK92 cells, pNK cells, and CD19-CAR-NK92 cells treated with pan-HDACi Dac and Pan at low nanomolar doses was significantly increased, although cell function was unaffected. Low doses of Dac upregulated the JAK-STAT signaling pathway and enhance the cell cycle via that pathway. In addition, the in vivo experiment in nude mice showed that the capacity of Dac treated NK92 cells to eliminate tumor cells was unaffected.

CONCLUSION

Low nanomolar doses of Pan-HDACi enhanced IL2-induced NK cell proliferation without compromising the functioning of NK cells.

Low Level FLT3LG is a Novel Poor Prognostic Biomarker for Cervical Cancer with Immune Infiltration

Introduction

The FMS-related tyrosine kinase 3 (FLT3) ligand (FLT3LG), a growth factor, binds to FLT3 on dendritic cell (DCs) to enhance their differentiation and expansion. It has shown great potential as an immunotherapy target for cancers. However, the expression and function of FLT3LG in cervical cancer remain largely unknown.

Materials and Methods

In this study, we obtained the expression of FLT3LG, the clinical prognosis in cervical cancer, via multiple databases, including The Cancer Genome Atlas (TCGA), the TISIDB database, and Tumor Immune Estimate Resource (TIMER). The results were further investigated using real-time quantitative PCR (qPCR) cytology specimens in 489 patients. Furthermore, Kaplan-Meier Cox regression and prognostic nomogram analyses were used to assess FLT3LG's clinical significance in cervical cancer patients. All calculations used the R package.

Results

As a result, FLT3LG expression decreased in cervical cancer compared with standard samples. And the low expression of FLT3LG was associated with a poor prognosis. Furthermore, Receiver Operating Characteristics (ROC) analysis indicated that FLT3LG might serve as a valuable diagnostic biomarker for cervical cancer. Additionally, it indicated that the FLT3LG had the highest odds ratio (OR=10.519; (7.371-27.071)) for detecting CIN 2+. In addition, our result also demonstrated that expression of FLT3LG was closely related to immune cells, immune inhibitors, immunostimulators, receptors, and chemokines in CESC.

Conclusion

Research on FLT3LG provided insight into its critical function. Hence, the low expression of FLT3LG may be a valuable biomarker in CESC patients linked with immune infiltration.

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

Simple Summary

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

Abstract

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

Natural killer cell homing and trafficking in tissues and tumors: from biology to application

Natural killer (NK) cells, a subgroup of innate lymphoid cells, act as the first line of defense against cancer. Although some evidence shows that NK cells can develop in secondary lymphoid tissues, NK cells develop mainly in the bone marrow (BM) and egress into the blood circulation when they mature. They then migrate to and settle down in peripheral tissues, though some special subsets home back into the BM or secondary lymphoid organs. Owing to its success in allogeneic adoptive transfer for cancer treatment and its "off-the-shelf" potential, NK cell-based immunotherapy is attracting increasing attention in the treatment of various cancers. However, insufficient infiltration of adoptively transferred NK cells limits clinical utility, especially for solid tumors. Expansion of NK cells or engineered chimeric antigen receptor (CAR) NK cells ex vivo prior to adoptive transfer by using various cytokines alters the profiles of chemokine receptors, which affects the infiltration of transferred NK cells into tumor tissue. Several factors control NK cell trafficking and homing, including cell-intrinsic factors (e.g., transcriptional factors), cell-extrinsic factors (e.g., integrins, selectins, chemokines and their corresponding receptors, signals induced by cytokines, sphingosine-1-phosphate (S1P), etc.), and the cellular microenvironment. Here, we summarize the profiles and mechanisms of NK cell homing and trafficking at steady state and during tumor development, aiming to improve NK cell-based cancer immunotherapy.

Significance of Placental Mesenchymal Stem Cell in Placenta Development and Implications for Preeclampsia

The well-developed placentation is fundamental for the reproductive pregnancy while the defective placental development is the pathogenetic basis of preeclampsia (PE), a dangerous complication of pregnancy comprising the leading causes of maternal and perinatal morbidity and mortality. Placenta-derived mesenchymal stem cells (PMSCs) are a group of multipotent stem cells that own a potent capacity of differentiating into constitutive cells of vessel walls. Additionally, with the paracrine secretion of various factors, PMSCs inextricably link and interact with other component cells in the placenta, collectively improving the placental vasculature, uterine spiral artery remolding, and uteroplacental interface immunoregulation. Recent studies have further indicated that preeclamptic PMSCs, closely implicated in the abnormal crosstalk between other ambient cells, disturb the homeostasis and development in the placenta. Nevertheless, PMSCs transplantation or PMSCs exosome therapies tend to improve the placental vascular network and trophoblastic functions in the PE model, suggesting PMSCs may be a novel and putative therapeutic strategy for PE. Herein, we provide an overview of the multifaceted contributions of PMSCs in early placental development. Thereinto, the intensive interactions between PMSCs and other component cells in the placenta were particularly highlighted and further extended to the implications in the pathogenesis and therapeutic strategies of PE.

Prognostic biomarker SGSM1 and its correlation with immune infiltration in gliomas

Objective

Glioma was the most common type of intracranial malignant tumor. Even after standard treatment, the recurrence and malignant progression of lower-grade gliomas (LGGs) were almost inevitable. The overall survival (OS) of patients with LGG varied widely, making it critical for prognostic prediction. Small G Protein Signaling Modulator 1 (SGSM1) has hardly been studied in gliomas. Therefore, we aimed to investigate the prognostic role of SGSM1 and its relationship with immune infiltration in LGGs.

Methods

We obtained RNA sequencing data from The Cancer Genome Atlas (TCGA) to analyze SGSM1 expression. Functional enrichment analyses, immune infiltration analyses, immune checkpoint analyses, and clinicopathology analyses were performed. Univariate and multivariate Cox regression analyses were used to identify independent prognostic factors. And nomogram model has been developed. Kaplan–Meier survival analysis and log-rank test were used to estimate the relationship between OS and SGSM1 expression. The survival analyses and Cox regression were validated in datasets from the Chinese Glioma Genome Atlas (CGGA).

Results

SGSM1 was significantly down-regulated in LGGs. Functional enrichment analyses revealed SGSM1 was correlated with immune response. Most immune cells and immune checkpoints were negatively correlated with SGSM1 expression. The Kaplan–Meier analyses showed that low SGSM1 expression was associated with a poor outcome in LGG and its subtypes. The Cox regression showed SGSM1 was an independent prognostic factor in patients with LGG (HR = 0.494, 95%CI = 0.311–0.784, P = 0.003).

Conclusion

SGSM1 was considered to be a new prognostic biomarker for patients with LGG. And our study provided a potential therapeutic target for LGG treatment.

New Orders to an Old Soldier: Optimizing NK Cells for Adoptive Immunotherapy in Hematology

NK (Natural Killer) cell-mediated adoptive immunotherapy has gained attention in hematology due to the progressing knowledge of NK cell receptor structure, biology and function. Today, challenges related to NK cell expansion and persistence in vivo as well as low cytotoxicity have been mostly overcome by pioneering trials that focused on harnessing NK cell functions. Recent technological advancements in gene delivery, gene editing and chimeric antigen receptors (CARs) have made it possible to generate genetically modified NK cells that enhance the anti-tumor efficacy and represent suitable “off-the-shelf” products with fewer side effects. In this review, we highlight recent advances in NK cell biology along with current approaches for potentiating NK cell proliferation and activity, redirecting NK cells using CARs and optimizing the procedure to manufacture clinical-grade NK and CAR NK cells for adoptive immunotherapy.

High expression of COMMD7 is an adverse prognostic factor in acute myeloid leukemia

Acute myeloid leukemia (AML) is a frequent malignancy in adults worldwide; identifying preferable biomarkers has become one of the current challenges. Given that COMMD7 has been reported associated with tumor progression in various human solid cancers but rarely reported in AML, herein, RNA sequencing data from TCGA and GTEx were obtained for analysis of COMMD7 expression and differentially expressed gene (DEG). Furthermore, functional enrichment analysis of COMMD7-related DEGs was performed by GO/KEGG, GSEA, immune cell infiltration analysis, and protein-protein interaction (PPI) network. In addition, the clinical significance of COMMD7 in AML was figured out by Kaplan-Meier Cox regression and prognostic nomogram model. R package was used to analyze incorporated studies. As a result, COMMD7 was highly expressed in various malignancies, including AML, compared with normal samples. Moreover, high expression of COMMD7 was associated with poor prognosis in 151 AML samples, as well as subgroups with age >60, NPM1 mutation-positive, FLT3 mutation-negative, and DNMT3A mutation-negative, et al. (P < 0.05). High COMMD7 was an independent prognostic factor in Cox regression analysis; Age and cytogenetics risk were included in the nomogram prognostic model. Furthermore, a total of 529 DEGs were identified between the high- and the low- expression group, of which 92 genes were up-regulated and 437 genes were down-regulated. Collectively, high expression of COMMD7 is a potential biomarker for adverse outcomes in AML. The DEGs and pathways recognized in the study provide a preliminary grasp of the underlying molecular mechanisms of AML carcinogenesis and progression.

EZH1/2 Inhibitors Favor ILC3 Development from Human HSPC-CD34+ Cells

Simple Summary

It has been well-demonstrated that EZH1/2 enzymes are involved not only in tumor development and progression, but also in the regulation of normal hematopoiesis from CD34⁺-HSPC. Given the crucial role of NK cells in tumor immune surveillance, in this study, we investigated whether EZH1/2 inhibitors can interfere with NK cell differentiation and functional maturation. Our results suggest that EZH1/2 inhibitors push CD56⁺ precursor proliferation, skewing precursor cell lineage commitment towards ILC3. In recent years, several clinical trials on the use of EZH1/2 inhibitors against solid tumors have been carried out. Since these in vitro observations revealed possible epigenetic mechanisms involved in NK/ILC development, it is important to evaluate patient monitoring of competent NK cells repertoire in order to design appropriate therapeutic protocols.

Abstract

The dysregulation of epigenetic modifications has a well-established role in the development and progression of hematological malignancies and of solid tumors. In this context, EZH1/2 inhibitors have been designed to interfere with EZH1/2 enzymes involved in histone methylation (e.g., H3K27me3), leading to tumor growth arrest or the restoration of tumor suppressor gene transcription. However, these compounds also affect normal hematopoiesis, interfering with self-renewal and differentiation of CD34⁺-Hematopoietic Stem/Progenitor Cells (HSPC), and, in turn, could modulate the generation of potential anti-tumor effector lymphocytes. Given the important role of NK cells in the immune surveillance of tumors, it would be useful to understand whether epigenetic drugs can modulate NK cell differentiation and functional maturation. CD34⁺-HSPC were cultured in the absence or in the presence of the EZH1/2 inhibitor UNC1999 and EZH2 inhibitor GSK126. Our results show that UNC1999 and GSK126 increased CD56⁺ cell proliferation compared to the control condition. However, UNC1999 and GSK 126 favored the proliferation of no-cytotoxic CD56⁺ILC3, according to the early expression of the AHR and ROR-γt transcription factors. Our results describe novel epigenetic mechanisms involved in the modulation of NK cell maturation that may provide new tools for designing NK cell-based immunotherapy.

Prognostic Value of the Modified Systemic Inflammation Score in Patients With Extranodal Natural Killer/T-Cell Lymphoma

Background

Extranodal natural killer/T-cell lymphoma (ENKTL) is a rare and extremely malignant tumor. The systemic inflammation score (SIS), which is based on the pretreatment level of lymphocyte-to-monocyte ratio (LMR) and serum albumin (Alb), has been shown to be of prognostic value in a number of cancers. We integrate several other pretreatment serum inflammatory indicators, including the neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), serum C-reactive protein (CRP) and albumin (Alb) level, to establish a modified systemic inflammatory scoring system to predict clinical outcomes of ENKTL.

Methods

A total of 184 patients with newly diagnosed ENKTL was retrospectively investigated. Systemic inflammatory indexes, including NLR, LMR, CRP, and Alb level were reviewed. Receiver operating characteristic (ROC) curve analysis was carried out to obtain the optimal cut-off value. The associations between cutoff values and overall survival (OS) were analyzed by Kaplan–Meier curves and Cox proportional models.

Results

The median age of patients was 44.0 years, ranging from 15 to 82 years. There were 129 (70.1%) male patient. About 57.1% of patients had stage III or IV disease. The optimal cut-off values of NLR and LMR in predicting OS were 3.1 and 2.4, respectively. The clinical standard of CRP and Alb levels at 10 and 40 mg/L, respectively, were chosen as the optimal cut-off values. By multivariate analysis, hemophilic syndrome (hazard ratio [HR]: 10.540, 95% confidence interval [CI]: 3.440–32.291, P < 0.001), advanced Ann Arbor stages (III–IV) (HR: 4.606, 95% CI: 1.661–12.774, P = 0.003), paranasal sinus invasion (HR: 2.323, 95% CI: 1.069–5.047, P = 0.033), NLR ≥ 3.1 (HR: 3.019, 95% CI: 1.317–6.923, P = 0.009), Alb level of <40 mg/L (HR: 0.350, 95% CI: 0.134–0.915, P = 0.032), and radiation therapy (HR: 0.430, 95% CI: 0.205–0.901, P = 0.025) were independent protective factors for ENKTL. We combined two inflammatory indexes NLR and Alb level to establish a modified systemic inflammation score (mSIS). These 184 patients were divided into 3 groups: group 1 (mSIS score of 0), group 2 (mSIS score of 1), and group 3 (mSIS score of 2). The mean OS of these three groups were 42 months (95% CI: 31.4–53.12), 77 months (95% CI: 68.5–87.5), and 89 months (95% CI: 71.4–82.7), respectively (P < 0.001). The Harrell’s concordance index (C-index) of mSIS is 0.725. The mSIS could be used to discriminate patients categorized in the low-risk group of International Prognostic Index (IPI) (P < 0.001) and the low-risk and intermediate-risk prognostic index of natural killer cell lymphoma (PINK) group (P = 0.019).

Conclusion

The pretreatment mSIS could be an independent prognostic factor for OS in patients with ENKTL and warrants further research.

Perinatal Mesenchymal Stromal Cells and Their Possible Contribution to Fetal-Maternal Tolerance

During pregnancy, a successful coexistence between the mother and the semi-allogenic fetus occurs which requires a dynamic immune system to guarantee an efficient immune protection against possible infections and tolerance toward fetal antigens. The mechanism of fetal-maternal tolerance is still an open question. There is growing in vitro and in vivo evidence that mesenchymal stromal cells (MSC) which are present in perinatal tissues have a prominent role in generating a functional microenvironment critical to a successful pregnancy. This review highlights the immunomodulatory properties of perinatal MSC and their impact on the major immune cell subsets present in the uterus during pregnancy, such as natural killer cells, antigen-presenting cells (macrophages and dendritic cells), and T cells. Here, we discuss the current understanding and the possible contribution of perinatal MSC in the establishment of fetal-maternal tolerance, providing a new perspective on the physiology of gestation.

Neuroimmune mechanisms of psychostimulant and opioid use disorders

Substance use disorders are global health problems with few effective treatment options. Unfortunately, most potential pharmacological treatments are hindered by abuse potential of their own, limited efficacy, or adverse side effects. As a consequence, there is a pressing need for the development of addiction treatments with limited abuse potential and fewer off target effects. Given the difficulties in developing new pharmacotherapies for substance use disorders, there has been growing interest in medications that act on non-traditional targets. Recent evidence suggests a role for dysregulated immune signaling in the pathophysiology of multiple psychiatric diseases. While there is evidence that immune responses in the periphery and the central nervous system are altered by exposure to drugs of abuse, the contributions of neuroimmune interactions to addictive behaviors are just beginning to be appreciated. In this review, we discuss the data on immunological changes seen in clinical populations with substance use disorders, as well as in translational animal models of addiction. Importantly, we highlight those mechanistic findings showing causal roles for central or peripheral immune mediators in substance use disorder and appropriate animal models. Based on the literature reviewed here, it is clear that brain-immune system interactions in substance use disorders are much more complex and important than previously understood. While much work remains to be done, there are tremendous potential therapeutic implications for immunomodulatory treatments in substance use disorders.

KLRG1+ natural killer cells exert a novel antifibrotic function in chronic hepatitis B

BACKGROUND & AIMS

Natural killer (NK) cells are known to exert strong antiviral activity. Killer cell lectin-like receptor subfamily G member 1 (KLRG1) is expressed by terminally differentiated NK cells and KLRG1-expressing lymphocytes are known to expand following chronic viral infections. We aimed to elucidate the previously unknown role of KLRG1 in the pathogenesis of chronic hepatitis B (CHB).

METHODS

KLRG1+ NK cells were taken from the blood and liver of healthy individuals and patients with CHB. The phenotype and function of these cells was assessed using flow cytometry and in vitro stimulation.

RESULTS

Patients with CHB had a higher frequency of KLRG1+ NK cells compared to healthy controls (blood 13.4 vs. 2.3%, p <0.0001 and liver 23.4 vs. 2.6%, p <0.01). KLRG1+ NK cells were less responsive to K562 and cytokine stimulation, but demonstrated enhanced cytotoxicity (9.0 vs. 4.8%, p <0.05) and IFN-γ release (8.0 vs. 1.5%, p <0.05) via antibody dependent cellular cytotoxicity compared to their KLRG1- counterparts. KLRG1+ NK cells possessed a mature phenotype, demonstrating stronger cytolytic activity and IFN-γ secretion against hepatic stellate cells (HSCs) than KLRG1- NK cells. Moreover, KLRG1+ NK cells more effectively induced primary HSC apoptosis in a TRAIL-dependent manner. Increased KLRG1+ NK cell frequency in the liver and blood was associated with lower fibrosis stage (F0/F1) in patients with CHB. Finally, the expression of CD44, degranulation and IFN-γ production were all increased in KLRG1+ NK cells following stimulation with osteopontin, the CD44 ligand, suggesting that HSC-derived osteopontin may cause KLRG1+ NK cell activation.

CONCLUSIONS

KLRG1+ NK cells likely play an antifibrotic role during the natural course of CHB infection. Harnessing this antifibrotic function may provide a novel therapeutic approach to treat liver fibrosis in patients with CHB.

LAY SUMMARY

Individuals that are chronically infected with hepatitis B virus (HBV) possess an increased number of immune cells, called natural killer (NK) cells expressing the surface marker KLRG1 in the blood and liver. Here, we demonstrate that these specific NK cells are able to kill activated stellate cells in the liver. Because activated stellate cells contribute to liver scarring, i.e. fibrosis, and subsequent liver dysfunction in individuals with chronic HBV infection, KLRG1+ NK cells are a novel immune cell type that can limit liver scarring.

Presence of innate lymphoid cells in pleural effusions of primary and metastatic tumors: Functional analysis and expression of PD-1 receptor

The tumor microenvironment (TM) contains a wide variety of cell types and soluble factors capable of suppressing immune responses. While the presence of NK cells in pleural effusions (PE) has been documented, no information exists on the presence of other innate lymphoid cell (ILC) subsets and on the expression of programmed cell death‐1 (PD‐1) in NK and ILC. The presence of ILC was assessed in PE of 54 patients (n = 33 with mesothelioma, n = 15 with adenocarcinoma and n = 6 with inflammatory pleural diseases) by cell staining with suitable antibody combinations and cytofluorimetric analysis. The cytokine production of ILC isolated from both PE and autologous peripheral blood was analyzed upon cell stimulation and intracytoplasmic staining. We show that, in addition to NK cells, also ILC1, ILC2 and ILC3 are present in malignant PE and that the prevalent subset is ILC3. PE‐ILC subsets produced their typical sets of cytokines upon activation. In addition, we analyzed the PD‐1 expression on NK/ILC by multiparametric flow‐cytometric analysis, while the expression of PD‐1 ligand (PD‐L1) was evaluated by immunohistochemical analysis. Both NK cells and ILC3 expressed functional PD‐1, moreover, both tumor samples and malignant PE‐derived tumor cell lines were PD‐L1⁺ suggesting that the interaction between PD‐1⁺ILC and PD‐L1⁺tumor cells may hamper antitumor immune responses mediated by NK and ILC.

What's new?

Pleural tumors result in effusions that are not well characterized. In this study, the authors found that pleural effusions from patients with primary mesothelioma or metastatic adenocarcinoma contain NK cells and other innate lymphoid cells (ILC). These immune cells were capable of expressing normal cytokines, including the checkpoint protein PD‐1. However, the tumor cells were found to express the ligand PD‐L1. These results suggest a PD‐1‐mediated inhibitory effect on lymphoid cells with potential anti‐tumor activity. Better understanding of this inhibition in the tumor microenvironment may lead to new targets for checkpoint‐inhibitor therapies.

Heterogeneity of NK Cells and Other Innate Lymphoid Cells in Human and Murine Decidua

Innate lymphoid cells (ILCs) represent a heterogeneous group of cells lacking genetically rearranged antigen receptors that derive from common lymphoid progenitors. Five major groups of ILCs have been defined based on their cytokine production pattern and developmental transcription factor requirements: namely, natural killer (NK) cells, ILC1s, ILC2s, ILC3s, and lymphoid tissue-inducer (LTi) cells. ILC1s, ILC2s, and ILC3s mirror the corresponding T helper subsets (Th1, Th2, and Th17, respectively) and produce cytokines involved in defense against pathogens, lymphoid organogenesis, and tissue remodeling. During the first trimester of pregnancy, decidual tissues contain high proportion of decidual NK (dNK) cells, representing up to 50% of decidual lymphocytes, and ILC3s. They release peculiar cytokines and chemokines that contribute to successful pregnancy. Recent studies revealed that ILCs display a high degree of plasticity allowing their prompt adaptation to environmental changes. Decidual NK cells may derive from peripheral blood NK cells migrated when pregnancy establishes or from in situ differentiation of hematopoietic precursors. Previous studies showed that human and murine decidua contain dNK cells, tissue resident NK cells, and ILC3s, all characterized by unique phenotypic and functional properties, most likely induced by decidual microenvironment to favor the establishment and the maintenance of pregnancy. Thus, during the early phase of pregnancy, the simultaneous presence of different ILC subsets further underscores the complexity of the cellular components of decidual tissues as well as the role of decidual microenvironment in shaping the plasticity and the function of ILCs.

Isolation, Expansion, and Characterization of Natural Killer Cells and Their Precursors as a Tool to Study Cancer Immunosurveillance

This chapter will describe the current methodologies to isolate and expand NK cells from Peripheral Blood (PB) or tissues for "in vitro" studies, including NK cell antitumor immune function. In addition, methods to induce NK cell maturation, differentiation, and expansion from CD34⁺ precursors will also be described. Finally, it will also be treated the topical issue of the characterization of new functionally and phenotypically defined NK cell subsets.

Human natural killer cells and other innate lymphoid cells in cancer: Friends or foes?

Innate lymphoid cells (ILC) including NK cells (cytotoxic) and the recently identified "helper" ILC1, ILC2 and ILC3, play an important role in innate defenses against pathogens. Notably, they mirror analogous T cell subsets, regarding the pattern of cytokine produced, while the timing of their intervention is few hours vs days required for T cell-mediated adaptive responses. On the other hand, the effectiveness of ILC in anti-tumor defenses is controversial. The relevance of NK cells in the control of tumor growth and metastasis has been well documented and they have been exploited in the therapy of high risk leukemia in the haploidentical hematopoietic stem cell transplantation setting. In contrast, the actual involvement of helper ILCs remains contradictory. Thus, while certain functional capabilities of ILC1 and ILC3 may favor anti-tumor responses, other functions could rather favor tumor growth, neo-angiogenesis, epithelial-mesenchymal transition and metastasis. In addition, ILC2, by secreting type-2 cytokines, are thought to induce a prevalent pro-tumorigenic effect. Finally, the function of both NK cells and helper ILCs may be inhibited by the tumor microenvironment, thus adding further complexity to the interplay between ILC and tumors.

Effect of Tyrosin Kinase Inhibitors on NK Cell and ILC3 Development and Function

Tyrosin kinase inhibitors (TKI) sharply improved the prognosis of Chronic Myeloid Leukemia (CML) and of Philadelphia+ Acute Lymphoblastic Leukemia (Ph+ALL) patients. However, TKI are not curative because of the development of resistance and lack of complete molecular remission in the majority of patients. Clinical evidences would support the notion that patient's immune system may play a key role in preventing relapses. In particular, increased proportions of terminally differentiated CD56+CD16+CD57+ NK cells have been reported to be associated with successful Imatinib therapy discontinuation or with a deep molecular response in Dasatinib-treated patients. In view of the potential role of NK cells in immune-response against CML, it is important to study whether any TKI have an effect on the NK cell development and identify possible molecular mechanism(s) by which continuous exposure to in vitro TKI may influence NK cell development and repertoire. To this end, CD34+ hematopoietic stem cells (HSC) were cultured in the absence or in the presence of Imatinib, Nilotinib, or Dasatinib. We show that all compounds exert an inhibitory effect on CD56+ cell recovery. In addition, Dasatinib sharply skewed the repertoire of CD56+ cell population, leading to an impaired recovery of CD56+CD117-CD16+CD94/NKG2A+EOMES+ mature cytotoxic NK cells, while the recovery of CD56+CD117+CD94/NKG2A-RORγt+ IL-22-producing ILC3 was not affected. This effect appears to involve the Dasatinib-mediated inhibition of Src kinases and, indirectly, of STAT5-signaling activation in CD34+ cells during first days of culture. Our studies, reveal a possible mechanism by which Dasatinib may interfere with the proliferation and maturation of fully competent NK cells, i.e., by targeting signaling pathways required for differentiation and survival of NK cells but not of ILC3.

Human Innate Lymphoid Cells: Their Functional and Cellular Interactions in Decidua

Innate lymphoid cells (ILC) are developmentally related cell subsets that play a major role in innate defenses against pathogens, in lymphoid organogenesis and in tissue remodeling. The best characterized ILC are natural killer (NK) cells. They are detectable in decidua in the early phases of pregnancy. During the first trimester, NK cells represent up to 50% of decidua lymphocytes. Differently from peripheral blood (PB) NK cells, decidual NK (dNK) cells are poorly cytolytic, and, instead of IFNγ, they release cytokines/chemokines that induce neo-angiogenesis, tissue remodeling, and placentation. dNK interact with resident myeloid cells and participate in the induction of regulatory T cells that play a pivotal role in maintaining an efficient fetal-maternal tolerance. dNK cells may originate from CD34⁺ precursor cells present in situ and/or from immature NK cells already present in endometrial tissue and/or from PB NK cells migrated to decidua. In addition to NK cells, also ILC3 are present in human decidua during the first trimester. Decidual ILC3 include both natural cytotoxic receptor (NCR)⁺ and NCR^- cells, producing respectively IL-8/IL-22/GM-CSF and TNF/IL-17. NCR⁺ILC3 have been shown to establish physical and functional interactions with neutrophils that, in turn, produce factors that are crucial for pregnancy induction/maintenance and for promoting the early inflammatory phase, a fundamental process for a successful pregnancy. While NCR⁺ILC3 display a stable phenotype, most of NCR^-ILC3 may acquire phenotypic and functional features of NCR⁺ILC3. In conclusion, both NK cells and ILC3 are present in human decidua and may establish functional interactions with immune and myeloid cells playing an important role both in innate defenses and in tissue building/remodeling/placentation during the early pregnancy. It is conceivable that altered numbers or function of these cells may play a role in pregnancy failure.

Nidogen-1 is a novel extracellular ligand for the NKp44 activating receptor

The release of soluble ligands of activating Natural Killer (NK) cell receptors may represent a regulatory mechanism of NK cell function both in physiologic and in pathologic conditions. Here, we identified the extracellular matrix protein Nidogen-1 (NID1) as a ligand of NKp44, an important activating receptor expressed by activated NK cells. When released as soluble molecule, NID1 regulates NK cell function by modulating NKp44-induced IFN-γ production or cytotoxicity. In particular, it also modulates IFN-γ production induced by Platelet-Derived Growth Factor (PDGF)-DD following NKp44 engagement. We also show that NID1 may be present at the cell surface. In this form or when bound to a solid support (bNID1), NID1 fails to induce NK cell cytotoxicity or cytokine release. However, analysis by mass spectrometry revealed that exposure to bNID1 can induce in human NK cells relevant changes in the proteomic profiles suggesting an effect on different biological processes.

Pharmacokinetic drug evaluation of daclizumab for the treatment of relapsing-remitting multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. Despite the availability of several disease-modifying therapies for relapsing MS, there is a need for highly efficacious targeted therapy with a favorable benefit-risk profile and a high level of treatment adherence. Daclizumab is a humanized monoclonal antibody directed against CD25, the α subunit of the high-affinity interleukin 2 (IL-2) receptor, that reversibly modulates IL-2 signaling. Areas covered: Daclizumab blocks the activation and expansion of autoreactive T cells that plays a role in the immune pathogenesis of MS. As its modulatory effects on the immune system, daclizumab's potential for use in MS was tested extensively showing a high efficacy in reducing relapse rate, disability progression and the number and volume of gadolinium-enhancing lesions on brain magnetic resonance imaging. Moreover, phase II and III trials showed a favorable pharmacokinetic (PK) profile with slow clearance, linear pharmacokinetics at doses above 100 mg and high subcutaneous bioavailability, not influenced by age, sex or other clinical parameters. Expert opinion: Among the new emerging drugs for MS, daclizumab also, thanks to a favorable PK profile, may represent an interesting and promising therapeutic option in the wide MS therapies armamentarium.

The diagnosis and management of NK/T-cell lymphomas

Extranodal natural killer (NK)/T-cell lymphoma is an aggressive malignancy of putative NK-cell origin, with a minority deriving from the T-cell lineage. Pathologically, the malignancy occurs in two forms, extranodal NK/T-cell lymphoma, nasal type; and aggressive NK-cell leukaemia. Lymphoma occur most commonly (80%) in the nose and upper aerodigestive tract, less commonly (20%) in non-nasal areas (skin, gastrointestinal tract, testis, salivary gland), and rarely as disseminated disease with a leukemic phase. Genetic analysis showed mutations of genes involved in the JAK/STAT pathway, RNA assembly, epigenetic regulation, and tumor suppression. In initial clinical evaluation, positron emission tomography computed tomography, and quantification of plasma EBV DNA are mandatory as they are useful for response monitoring and prognostication. In stage I/II diseases, combined chemotherapy and radiotherapy (sequentially or concurrently) is the best approach. Conventional anthracycline-containing regimens are ineffective and should be replaced by non-anthracycline-containing regimens, preferably including L-asparaginase. Radiotherapy alone is associated with high systemic relapse rates and should be avoided. In stage III/IV diseases, non-anthracycline-regimens-containing L-asparaginase are the standard. In relapsed/refractory cases, blockade of the programmed death protein 1 has recently shown promising results with high response rates. In the era of effective non-anthracycline-containing regimens, autologous haematopoietic stem cell transplantation (HSCT) has not been shown to be beneficial. However, allogeneic HSCT may be considered for high-risk or advanced-stage patients in remission or relapsed/refractory patients responding to salvage therapy. Prognostic models taking into account presentation, interim, and end-of-treatment parameters are useful in triaging patients to different treatment strategies.

Natural Killer Cell Development and Maturation Revisited: Possible Implications of a Novel Distinct Lin-CD34+DNAM-1brightCXCR4+ Cell Progenitor

Since the first description of natural killer (NK) cells, the view on their role in innate immunity has evolved considerably. In addition to first-line defense against transformed and pathogen-infected autologous cells, NK cells contribute to modulate adaptive immune responses and in some cases acquire specialized functions, including exhausted, adaptive, and decidual NK cells. NK cells derive from CD34⁺ progenitors, in vivo and in vitro; however, it is unclear whether the high phenotype diversity in vivo may be generated from these precursors alone. The recent characterization of a novel CD34⁺DNAM-1^brightCXCR4⁺ precursor giving rise to apparently licensed and functional maturing NK cells may suggest the possibility for a higher than expected common lymphocyte precursor diversity and a consequently higher peripheral NK cell phenotype variability. Here, we review the evidences on NK cell central and peripheral development from CD34⁺ precursors and propose a possible updated reading frame based on the characterization of CD34⁺DNAM-1^brightCXCR4⁺ cell progenies, which favors the possibility of concurrent NK cell maturation from different CD34⁺ precursors.

IL15 induces a potent antitumor activity in NK cells isolated from malignant pleural effusions and overcomes the inhibitory effect of pleural fluid

Natural Killer (NK) cells are capable of recognizing and killing cancer cells and play an important role in tumor immunosurveillance. However, tumor-infiltrating NK cells are frequently impaired in their functional capability. A remarkable exception is represented by NK cells isolated from malignant pleural effusions (PE) that are not anergic and, upon IL2-induced activation, efficiently kill tumor cells. Although IL2 is used in various clinical trials, severe side effects may occur in treated patients. In this study, we investigated whether also other clinical-grade cytokines could induce strong cytotoxicity in NK cells isolated from pleural fluid of patients with primary or metastatic tumors of different origins. We show that PE-NK cells, cultured for short-time intervals with IL15, maintain the CD56^bright phenotype, a high expression of the main activating receptors, produce cytokines and kill tumor cells in vitro similarly to those treated with IL2. Moreover, IL15-activated PE-NK cells could greatly reduce the growth of established tumors in mice. This in vivo antitumor effect correlated with the ability of IL15-activated PE-NK cells to traffic from periphery to the tumor site. Finally, we show that IL15 can counteract the inhibitory effect of the tumor pleural microenvironment. Our study suggests that IL15-activated NK cells isolated from pleural fluid (otherwise discarded after thoracentesis) may represent a suitable source of effector cells to be used in adoptive immunotherapy of cancer.

Group 3 innate lymphoid cells regulate neutrophil migration and function in human decidua

Innate lymphoid cells (ILCs) have a central role in innate defenses against pathogens, lymphoid organogenesis, and tissue remodeling. They have been detected in human decidua, however, their role in this tissue remains unclear. Successful pregnancy requires an early inflammatory phase favoring implantation and tissue remodeling as well as a subsequent regulatory phase to prevent fetal rejection and supporting neoangiogenesis. Here, we show that, during the first trimester of pregnancy, neutrophils infiltrate decidua basalis and are more abundant in normal pregnancy than in spontaneous miscarriages. Decidual neutrophils localize in proximity of NCR⁺ILC3, which may influence neutrophil migration and survival given their production of CXCL8 and granulocyte macrophage colony-stimulating factor (GM-CSF). Moreover, NCR⁺ILC3-derived GM-CSF was found to induce the expression of heparin-binding EGF-like growth factor and IL1ra in neutrophils, two proteins/cytokines involved in tissue remodeling and maintenance of pregnancy. Our data suggest that the simultaneous presence of NCR⁺ILC3 and neutrophils in decidual tissues and their possible cross talk, may have a role in the early phases of pregnancy.

Diagnosis and management of extranodal NK/T cell lymphoma nasal type

INTRODUCTION

Extranodal NK/T-cell lymphoma nasal type is a distinct clinicopathologic entity. The most common initial site of presentation is the nasopharyngeal area, but non-nasals sites including the skin and the gastrointestinal tract may be affected.

AREAS COVERED

The diagnosis and management of NK/T-cell lymphoma is discussed, based on a literature search on PubMed. NK/T-cell lymphoma are typically positive for CD3 (cytoplasmic), CD56, cytotoxic markers (granzyme B, TIA1) and Epstein Barr virus (EBV). Plasma EBV DNA is an accurate surrogate biomarker for lymphoma load. For stage I/II nasal lymphoma, a combination of chemotherapy and radiotherapy yields the best results. Concomitant chemoradiotherapy and sequential chemotherapy and radiotherapy give similar response rates and survivals. For stage III/IV nasal lymphoma and non-nasal lymphomas, chemotherapy is the mainstay of treatment. Conventional anthracycline-based regimens are ineffective. Recommended chemotherapy protocols are based on the use of L-asparaginase combined with other effective drugs. Durable remission can be expected in at least 60% of patients irrespective of stage. Prognostically models based on clinicopathologic parameters and EBV DNA load are useful in stratification of patients for therapy. Expert commentary: Current treatment leads to long-term survival in a significant proportion of patients. For relapsed patients, novel strategies are needed.

Human Circulating and Tissue-Resident CD56(bright) Natural Killer Cell Populations

Two human natural killer (NK) cell subsets are usually distinguished, displaying the CD56^dimCD16⁺ and the CD56^brightCD16^−/+ phenotype. This distinction is based on NK cells present in blood, where the CD56^dim NK cells predominate. However, CD56^bright NK cells outnumber CD56^dim NK cells in the human body due to the fact that they are predominant in peripheral and lymphoid tissues. Interestingly, within the total CD56^bright NK cell compartment, a major phenotypical and functional diversity is observed, as demonstrated by the discovery of tissue-resident CD56^bright NK cells in the uterus, liver, and lymphoid tissues. Uterus-resident CD56^bright NK cells express CD49a while the liver- and lymphoid tissue-resident CD56^bright NK cells are characterized by co-expression of CD69 and CXCR6. Tissue-resident CD56^bright NK cells have a low natural cytotoxicity and produce little interferon-γ upon monokine stimulation. Their distribution and specific phenotype suggest that the tissue-resident CD56^bright NK cells exert tissue-specific functions. In this review, we examine the CD56^bright NK cell diversity by discussing the distribution, phenotype, and function of circulating and tissue-resident CD56^bright NK cells. In addition, we address the ongoing debate concerning the developmental relationship between circulating CD56^bright and CD56^dim NK cells and speculate on the position of tissue-resident CD56^bright NK cells. We conclude that distinguishing tissue-resident CD56^bright NK cells from circulating CD56^bright NK cells is a prerequisite for the better understanding of the specific role of CD56^bright NK cells in the complex process of human immune regulation.

Human NK cells: From surface receptors to clinical applications

Natural killer (NK) cells play a major role in innate defenses against pathogens, primarily viruses, and are also thought to be part of the immunosurveillance against tumors. They express an array of surface receptors that mediate NK cell function. The human leukocytes antigen (HLA) class I-specific inhibitory receptors allow NK cells to detect and kill cells that have lost or under-express HLA class I antigens, a typical feature of tumor or virally infected cells. However, NK cell activation and induction of cytolytic activity and cytokine production depends on another important checkpoint, namely the expression on target cells of ligands recognized by activating NK receptors. Despite their potent cytolytic activity, NK cells frequently fail to eliminate tumors. This is due to mechanisms of tumor escape, determined by the tumor cells themselves or by tumor-associated cells (i.e. the tumor microenvironment) via the release of soluble suppressive factors or the induction of inhibitory loops involving induction of regulatory T cells, M2-polarized macrophages and myeloid-derived suppressor cells. The most important clinical application involving NK cells is the cure of high-risk leukemias in the haplo-identical hematopoietic stem cell transplant (HSCT) setting. NK cells originated from hematopoietic stem cells (HSC) of HLA-haploidentical donors may express Killer Immunoglobulin-like receptors (KIRs) that are mismatched with the HLA class I alleles of the recipient. This allows NK cells to kill leukemia blasts residual after the conditioning regimen, while sparing normal cells (that do not express ligands for activating NK receptors). More recent approaches based on the specific removal of TCR α/β(+) T cells and of CD19(+) B cells, allow the infusion, together with CD34(+) HSC, of mature KIR(+) NK cells and of TCR γ/δ(+) T cells, both characterized by a potent anti-leukemia activity. This greatly reduces the time interval necessary to obtain alloreactive, KIR(+) NK cells derived from donor HSC. Another promising approach is based on the use of anti-KIR blocking monoclonal antibodies (mAbs), rendering alloreactive any KIR(+) NK cells.

NK Cells, Tumor Cell Transition, and Tumor Progression in Solid Malignancies: New Hints for NK-Based Immunotherapy?

Several evidences suggest that NK cells can patrol the body and eliminate tumors in their initial phases but may hardly control established solid tumors. Multiple factors, including the transition of tumor cells towards a proinvasive/prometastatic phenotype, the immunosuppressive effect of the tumor microenvironment, and the tumor structure complexity, may account for limited NK cell efficacy. Several putative mechanisms of NK cell suppression have been defined in these last years; conversely, the cross talk between NK cells and tumor cells undergoing different transitional phases remains poorly explored. Nevertheless, recent in vitro studies and immunohistochemical analyses on tumor biopsies suggest that NK cells could not only kill tumor cells but also influence their evolution. Indeed, NK cells may induce tumor cells to change the expression of HLA-I, PD-L1, or NKG2D-L and modulate their susceptibility to the immune response. Moreover, NK cells may be preferentially located in the borders of tumor masses, where, indeed, tumor cells can undergo Epithelial-to-Mesenchymal Transition (EMT) acquiring prometastatic phenotype. Finally, the recently highlighted role of HMGB1 both in EMT and in amplifying the recruitment of NK cells provides further hints on a possible effect of NK cells on tumor progression and fosters new studies on this issue.

Regulation of Natural Killer Cell Function by STAT3

Natural killer (NK) cells, key members of a distinct hematopoietic lineage, innate lymphoid cells, are not only critical effectors that mediate cytotoxicity toward tumor and virally infected cells but also regulate inflammation, antigen presentation, and the adaptive immune response. It has been shown that NK cells can regulate the development and activation of many other components of the immune response, such as dendritic cells, which in turn, modulate the function of NK cells in multiple synergistic feed back loops driven by cell–cell contact, and the secretion of cytokines and chemokines that control effector function and migration of cells to sites of immune activation. The signal transducer and activator of transcription (STAT)-3 is involved in driving almost all of the pathways that control NK cytolytic activity as well as the reciprocal regulatory interactions between NK cells and other components of the immune system. In the context of tumor immunology, NK cells are a first line of defense that eliminates pre-cancerous and transformed cells early in the process of carcinogenesis, through a mechanism of “immune surveillance.” Even after tumors become established, NK cells are critical components of anticancer immunity: dysfunctional NK cells are often found in the peripheral blood of cancer patients, and the lack of NK cells in the tumor microenvironment often correlates to poor prognosis. The pathways and soluble factors activated in tumor-associated NK cells, cancer cells, and regulatory myeloid cells, which determine the outcome of cancer immunity, are all critically regulated by STAT3. Using the tumor microenvironment as a paradigm, we present here an overview of the research that has revealed fundamental mechanisms through which STAT3 regulates all aspects of NK cell biology, including NK development, activation, target cell killing, and fine tuning of the innate and adaptive immune responses.

Natural killer cell immunosenescence in acute myeloid leukaemia patients: new targets for immunotherapeutic strategies?

Several age-associated changes in natural killer (NK) cell phenotype have been reported that contribute to the defective NK cell response observed in elderly patients. A remodelling of the NK cell compartment occurs in the elderly with a reduction in the output of immature CD56(bright) cells and an accumulation of highly differentiated CD56(dim) NK cells. Acute myeloid leukaemia (AML) is generally a disease of older adults. NK cells in AML patients show diminished expression of several activating receptors that contribute to impaired NK cell function and, in consequence, to AML blast escape from NK cell immunosurveillance. In AML patients, phenotypic changes in NK cells have been correlated with disease progression and survival. NK cell-based immunotherapy has emerged as a possibility for the treatment of AML patients. The understanding of age-associated alterations in NK cells is therefore necessary to define adequate therapeutic strategies in older AML patients.

Cutaneous adverse events in multiple sclerosis patients treated with daclizumab

OBJECTIVE

To analyze the spectrum and mechanisms of cutaneous adverse events (AEs) in patients with multiple sclerosis treated with daclizumab high-yield process (DAC-HYP).

METHODS

A total of 31 participants in an institutional review board-approved open-label phase I study of DAC-HYP (NCT01143441) were prospectively evaluated over 42 months for development of cutaneous AEs. Participants provided written informed consent. Fifteen participants were naive to anti-CD25 therapy (cohort B), while 16 had received daclizumab (Zenapax; Hoffmann-La Roche) IV for 4-9 years (mean 5.8 years) prior to enrollment (cohort A). Immunohistochemistry was performed on pretreatment and posttreatment skin biopsies of normal-appearing skin (cohort B only) and on lesional biopsies in participants presenting with rash (both cohorts).

RESULTS

Cutaneous AEs occurred in 77% of patients, the majority presenting with patches of eczema requiring no treatment. Moderate to severe rash developed in 6 participants (19%) and required discontinuation of DAC-HYP in 4 (13%). More severe rashes presented psoriasiform phenotype, but lesional biopsies lacked features of either psoriasis or drug hypersensitivity eruptions. Instead, irrespective of clinical severity, lesional biopsies showed nonspecific features of eczematous dermatitis, but with prominent CD56+ lymphocytic infiltrates. Pretreatment and posttreatment biopsies of normal-appearing skin demonstrated no histopathologic changes.

CONCLUSIONS

Observed cutaneous AEs are likely related to the immunomodulatory effects DAC-HYP exerts on innate lymphoid cells, including natural killer cells. Vigilance and timely management of skin reactions may prevent treatment discontinuation in participants with severe rash.

NCR1+ cells appear early in GALT development of the ovine foetus and acquire a c-kit+ phenotype towards the end of gestation

The amount, distribution and phenotype of ovine NCR1+ cells were investigated during developing GALT from day 70 of gestation. Antibodies against CD3 and CD79 were used to identify the compartments of GALT, and the localization of NCR1+ cells were correlated within these structures. Markers CD34 and c-kit, in addition to Ki67, were used to investigate possible origin and the stage of development of the NCR1+ cells. NCR1+ cells were present as single cells in the subepithelial tissue as early as 70 days of gestation, and were predominantly present in the T cell rich IFAs and domes as these intestinal wall compartments developed. While NCR1+ cells proliferated more intensively at mid-gestation (70-104 days), the number of NCR1+ cells also expressing c-kit, increased at the end of gestation. In conclusion, NCR1+ cells appeared early in T cell areas of the gut and displayed a phenotype consistent with intermediate stages of cNK cells and/or a subpopulation of ILC22.

Innate lymphoid cells involve in tumorigenesis

Innate lymphoid cells (ILCs) promptly initiate cytokine responses to pathogen exposure in the mucosa and mucosal-associated lymphoid tissues. ILCs were recently categorized as being of the lymphoid lineage and have been classified into three groups. ILCs play important roles in immunity against pathogens, and an anti-tumor immune-related function was recently demonstrated. In this review we discuss whether and how ILCs involve in the tumorigenesis, providing new insights into the mechanisms underlying the particular functions of ILCs as well as the potential targets for tumor intervention.

Group 2 Innate Lymphoid Cells Express Functional NKp30 Receptor Inducing Type 2 Cytokine Production

Group 2 innate lymphoid cells (ILC2) are important in effector functions for eliciting allergic inflammation, parasite defense, epithelial repair, and lipid homeostasis. ILC2 lack rearranged Ag-specific receptors, and although many soluble factors such as cytokines and lipid mediators can influence ILC2, direct interaction of these cells with the microenvironment and other cells has been less explored. Natural cytotoxicity receptors are expressed by subsets of group 1 ILC and group 3 ILC and thought to be important for their effector function, but they have not been shown to be expressed by ILC2. Therefore, we sought to investigate the expression and functional properties of the natural cytotoxicity receptor NKp30 on human ILC2. A subset of ex vivo and cultured ILC2 express NKp30 that upon interaction with its cognate activatory ligand B7-H6 induces rapid production of type 2 cytokines. This interaction can be blocked by NKp30 blocking Ab and an inhibitory ligand, galectin-3. Higher expression of B7-H6 was observed in lesional skin biopsies of patients with atopic dermatitis, and incubation of keratinocytes with proinflammatory and type 2 cytokines upregulated B7-H6, leading to increased ILC2 cytokine production. NKp30-B7-H6 interaction is a novel cell contact mechanism that mediates activation of ILC2 and identifies a potential target for the development of novel therapeutics for atopic dermatitis and other atopic diseases.

Role of NK cells in immunotherapy and virotherapy of solid tumors

Although natural killer (NK) cells are endowed with powerful cytolytic activity against cancer cells, their role in different therapies against solid tumors has not yet been fully elucidated. Their interactions with various elements of the tumor microenvironment as well as their possible effects in contributing to and/or limiting oncolytic virotherapy render this potential immunotherapeutic tool still difficult to exploit at the bedside. Here, we will review the current literature with the aim of providing new hints to manage this powerful cell type in future innovative therapies, such as the use of NK cells in combination with new cytokines, specific mAbs (inducing ADCC), Tyr-Kinase inhibitors, immunomodulatory drugs and/or the design of oncolytic viruses aimed at optimizing the effect of NK cells in virotherapy.

MSC and innate immune cell interactions: A lesson from human decidua

Both experimental and clinical studies revealed that stromal cells (SC) are present in decidua (DSC) and placenta (PSC) at the early and late phase of pregnancy, respectively, and they may contribute to the induction of an anti-inflammatory/tolerogenic microenvironment crucial for the establishment/maintenance of successful pregnancy. These cells share common features with mesenchymal SC. In the present contribution, we provide an overall view on DSC features and on their ability to recruit NK cells and to regulate both differentiation and function not only of NK cells but also of CD14(+) myeloid cells. NK cells represent the large majority of leukocytes populating decidual tissues during the first trimester of pregnancy. Their cross-talk with DSC is thought to play a key role in the establishment of feto-maternal tolerance. We also discuss recent data suggesting that DSC may contribute to tissue remodeling, placentation, and recruitment of leukocytes also through their interaction with innate lymphoid cells (ILC) such as ILC3, that have recently been shown to be present in decidual tissue.

Human natural killer cells: origin, receptors, function, and clinical applications

Natural killer (NK) cells are important effectors playing a relevant role in innate immunity, primarily in tumor surveillance and in defenses against viruses. Human NK cells recognize HLA class I molecules through surface receptors (KIR and NKG2A) that inhibit NK cell function and kill target cells that have lost (or underexpress) HLA class I molecules as it occurs in tumors or virus-infected cells. NK cell activation is mediated by an array of activating receptors and co-receptors that recognize ligands expressed primarily on tumors or virus-infected cells. In vivo anti-tumor NK cell activity may be suppressed by tumor or tumor-associated cells. Alloreactive NK cells (i.e. those that are not inhibited by the HLA class I alleles of the patient) derived from HSC of haploidentical donors play a major role in the cure of high-risk leukemia, by killing leukemia blasts and patient's DC, thus preventing tumor relapses and graft-versus-host disease. The expression of the HLA-C2-specific activating KIR2DS1 may also contribute to NK alloreactivity in patients expressing C2 alleles. A clear correlation has been proven between the size of the alloreactive NK cell population and the clinical outcome. Recently, haplo-HSCT has been further improved with the direct infusion, together with HSC, of donor-derived, mature alloreactive NK cells and TCRγδ(+) T cells - both contributing to a prompt anti-leukemia effect together with an efficient defense against pathogens during the 6- to 8-week interval required for the generation of alloreactive NK cells from HSC.

Key mediators in the immunopathogenesis of allergic asthma

Asthma is described as a chronic inflammatory disorder of the conducting airways. It is characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyper-responsiveness and airway remodeling. Our findings to date have largely been dependent on work done using animal models, which have been instrumental in broadening our understanding of the mechanism of the disease. However, using animals to model a uniquely human disease is not without its drawbacks. This review aims to examine some of the key mediators and cells of allergic asthma learned from animal models and shed some light on emerging mediators in the pathogenesis allergic airway inflammation in acute and chronic asthma.