LFA-1 contributes an early signal for NK cell cytotoxicity

A Critical Role of Culture Medium Selection in Maximizing the Purity and Expansion of Natural Killer Cells

Natural killer (NK) cells hold promise in cancer treatment due to their ability to spontaneously lyse cancer cells. For clinical use, high quantities of pure, functional NK cells are necessary. Combining adherence-based isolation with specialized media showed the unreliability of the isolation method, but demonstrated the superiority of the NK MACS® medium, particularly in suboptimal conditions. Neither human pooled serum, fetal calf serum (FCS), human platelet lysate, nor chemically defined serum replacement could substitute human AB serum. Interleukin (IL-)2, IL-15, IL-21, and combined CD2/NKp46 stimulation were assessed. IL-21 and CD2/NKp46 stimulation increased cytotoxicity, but reduced NK cell proliferation. IL-15 stimulation alone achieved the highest proliferation, but the more affordable IL-2 performed similarly. The RosetteSep™ human NK cell enrichment kit was effective for isolation, but the presence of peripheral blood mononuclear cells (PBMCs) in the culture enhanced NK cell proliferation, despite similar expression levels of CD16, NKp46, NKG2D, and ICAM-1. In line with this, purified NK cells cultured in NK MACS® medium with human AB serum and IL-2 demonstrated high cytotoxicity against primary glioblastoma stem cells.

Exploring novel protein biomarkers for early-stage diagnosis and prognosis of T-acute lymphoblastic leukemia (T-ALL)

BACKGROUND

Efficient classification of T-acute lymphoblastic leukemia (T-ALL) involves considering various factors, such as age, white blood cell count, and chromosomal alterations. However, studying protein markers are crucial to improving T-ALL patients' diagnosis and treatment. A study analyzing the expression of proteomes was conducted to identify promising early-stage biomarkers for T-ALL patients METHODS: Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyze the blood proteins of both patients and healthy individuals to identify new biomarkers for T-ALL. The findings were validated by RT-PCR, ELISA and computational analysis RESULTS: The study identified 1467 proteins in the blood, of which nine were upregulated and 35 were downregulated by more than 2-fold. T-ALL patients showed a significant increase in specific disease-related proteins, such as eleven-nineteen lysine-rich leukemia protein, triggering receptor expressed on myeloid cells 1, cisplatin resistance-associated-overexpressed protein, X-ray radiation resistance-associated protein 1, tumor necrosis factor receptor superfamily member 10D, protein S100-A8, and copine-4, by more than 3-fold CONCLUSION: The findings of this study provide a valuable protein map of leukemic cells and identify potential biomarkers for leukemic aggressiveness. However, further studies using larger T-ALL patient samples must confirm these preliminary results.

Identification of diagnostic model in heart failure with myocardial fibrosis and conduction block by integrated gene co-expression network analysis

BACKGROUND

Despite the advancements in heart failure(HF) research, the early diagnosis of HF continues to be a challenging issue in clinical practice. This study aims to investigate the genes related to myocardial fibrosis and conduction block, with the goal of developing a diagnostic model for early treatment of HF in patients.

METHOD

The gene expression profiles of GSE57345, GSE16499, and GSE9128 were obtained from the Gene Expression Omnibus (GEO) database. After merging the expression profile data and adjusting for batch effects, differentially expressed genes (DEGs) associated with conduction block and myocardial fibrosis were identified. Gene Ontology (GO) resources, Kyoto Encyclopedia of Genes and Genomes (KEGG) resources, and gene set enrichment analysis (GSEA) were utilized for functional enrichment analysis. A protein-protein interaction network (PPI) was constructed using a string database. Potential key genes were selected based on the bioinformatics information mentioned above. SVM and LASSO were employed to identify hub genes and construct the module associated with HF. The mRNA levels of TAC mice and external datasets (GSE141910 and GSE59867) are utilized for validating the diagnostic model. Additionally, the study explores the relationship between the diagnostic model and immune cell infiltration.

RESULTS

A total of 395 genes exhibiting differential expression were identified. Functional enrichment analysis revealed that these specific genes primarily participate in biological processes and pathways associated with the constituents of the extracellular matrix (ECM), immune system processes, and inflammatory responses. We identified a diagnostic model consisting of 16 hub genes, and its predictive performance was validated using external data sets and a transverse aortic coarctation (TAC) mouse model. In addition, we observed significant differences in mRNA expression of 7 genes in the TAC mouse model. Interestingly, our study also unveiled a correlation between these model genes and immune cell infiltration.

CONCLUSIONS

We identified sixteen key genes associated with myocardial fibrosis and conduction block, as well as diagnostic models for heart failure. Our findings have significant implications for the intensive management of individuals with potential genetic variants associated with heart failure, especially in the context of advancing cell-targeted therapy for myocardial fibrosis.

Prostaglandin E₂ impacts multiple stages of the natural killer cell antitumor immune response

Tumor immune escape is a major factor contributing to cancer progression and unresponsiveness to cancer therapies. Tumors can produce prostaglandin E2 (PGE2 ), an inflammatory mediator that directly acts on Natural killer (NK) cells to inhibit antitumor immunity. However, precisely how PGE2 influences NK cell tumor-restraining functions remains unclear. Here, we report that following PGE₂ treatment, human NK cells exhibited altered expression of specific activating receptors and a reduced ability to degranulate and kill cancer targets. Transcriptional analysis uncovered that PGE₂ also differentially modulated the expression of chemokine receptors by NK cells, inhibiting CXCR3 but increasing CXCR4. Consistent with this, PGE₂-treated NK cells exhibited decreased migration to CXCL10 but increased ability to migrate toward CXCL12. Using live cell imaging, we showed that in the presence of PGE2 , NK cells were slower and less likely to kill cancer target cells following conjugation. Imaging the sequential stages of NK cell killing revealed that PGE₂ impaired NK cell polarization, but not the re-organization of synaptic actin or the release of perforin itself. Together, these findings demonstrate that PGE₂ affects multiple but select NK cell functions. Understanding how cancer cells subvert NK cells is necessary to more effectively harness the cancer-inhibitory function of NK cells in treatments.

Proteomics reveals a global phenotypic shift of NK cells in HCV patients treated with direct-acting antivirals

Chronic hepatitis C virus (HCV) infections compromise natural killer (NK)-cell immunity. Direct-acting antivirals (DAA) effectively eliminate HCV, but the long-term effects on NK cells in cured patients are debated. We conducted a proteomic study on CD56+ NK cells of chronic HCV-infected patients before and 1 year after DAA therapy. Donor-variation was observed in NK-cell proteomes of HCV-infected patients, with 46 dysregulated proteins restored after DAA therapy. However, 30% of the CD56+ NK-cell proteome remained altered 1 year post-therapy, indicating a phenotypic shift with low donor-variation. NK cells from virus-negative cured patients exhibited global regulation of RNA-processing and pathways related to "stimuli response", "chemokine signaling", and "cytotoxicity regulation". Proteomics identified downregulation of vesicle transport components (CD107a, COPI/II complexes) and altered receptor expression profiles, indicating an inhibited NK-cell phenotype. Yet, activated NK cells from HCV patients before and after therapy effectively upregulated IFN-γ and recruited CD107a. Conversely, reduced surface expression levels of Tim-3 and 2B4 were observed before and after therapy. In conclusion, this study reveals long-term effects on the CD56+ NK-cell compartment in convalescent HCV patients 1 year after therapy, with limited abundance of vesicle transport complexes and surface receptors, associated with a responsive NK-cell phenotype.

Actin cytoskeleton remodeling at the cancer cell side of the immunological synapse: good, bad, or both?

Cytotoxic lymphocytes (CLs), specifically cytotoxic T lymphocytes and natural killer cells, are indispensable guardians of the immune system and orchestrate the recognition and elimination of cancer cells. Upon encountering a cancer cell, CLs establish a specialized cellular junction, known as the immunological synapse that stands as a pivotal determinant for effective cell killing. Extensive research has focused on the presynaptic side of the immunological synapse and elucidated the multiple functions of the CL actin cytoskeleton in synapse formation, organization, regulatory signaling, and lytic activity. In contrast, the postsynaptic (cancer cell) counterpart has remained relatively unexplored. Nevertheless, both indirect and direct evidence has begun to illuminate the significant and profound consequences of cytoskeletal changes within cancer cells on the outcome of the lytic immunological synapse. Here, we explore the understudied role of the cancer cell actin cytoskeleton in modulating the immune response within the immunological synapse. We shed light on the intricate interplay between actin dynamics and the evasion mechanisms employed by cancer cells, thus providing potential routes for future research and envisioning therapeutic interventions targeting the postsynaptic side of the immunological synapse in the realm of cancer immunotherapy. This review article highlights the importance of actin dynamics within the immunological synapse between cytotoxic lymphocytes and cancer cells focusing on the less-explored postsynaptic side of the synapse. It presents emerging evidence that actin dynamics in cancer cells can critically influence the outcome of cytotoxic lymphocyte interactions with cancer cells.

Non-coding RNAs: emerging roles in the characterization of immune microenvironment and immunotherapy of prostate cancer

Prostate cancer is the most common tumor among men. Although the prognosis for early-stage prostate cancer is good, patients with advanced disease often progress to metastatic castration-resistant prostate cancer (mCRPC), which usually leads to death owing to resistance to existing treatments and lack of long-term effective therapy. In recent years, immunotherapy, especially immune checkpoint inhibitors (ICIs), has made great progress in the treatment of various solid tumors, including prostate cancer. However, the ICIs have only shown modest outcomes in mCRPC compared with other tumors. Previous studies have suggested that the suppressive tumor immune microenvironment (TIME) of prostate cancer leads to poor anti-tumor immune response and tumor resistance to immunotherapy. It has been reported that non-coding RNAs (ncRNAs) are capable of regulating upstream signaling at the transcriptional level, leading to a "cascade of changes" in downstream molecules. As a result, ncRNAs have been identified as an ideal class of molecules for cancer treatment. The discovery of ncRNAs provides a new perspective on TIME regulation in prostate cancer. ncRNAs have been associated with establishing an immunosuppressive microenvironment in prostate cancer through multiple pathways to modulate the immune escape of tumor cells which can promote resistance of prostate cancer to immunotherapy. Targeting these related ncRNAs presents an opportunity to improve the effectiveness of immunotherapy in this patient population.

Evidence-based mechanisms of synergy with IMiD agent-based combinations in multiple myeloma

Treatment of multiple myeloma (MM) has seen great advances in recent years, and a key contributor to this change has been the effective use of combination therapies, which have improved both the depth and duration of patient responses. IMiD agents (lenalidomide and pomalidomide) have both tumoricidal and immunostimulatory functions, and due to their multiple mechanisms of action have become the backbone of numerous combination treatments in the newly diagnosed and relapsed/refractory settings. Although IMiD agent-based combination regimens provide improved clinical outcomes for patients with MM, the mechanisms underpinning these combinations are not well understood. In this review we describe the potential mechanisms of synergy leading to the enhanced activity observed when IMiD agents and other drug classes are used in combination through interrogation of the current knowledge surrounding their mechanism of actions.

Upregulation of CD226 on subsets of T cells and NK cells is associated with upregulated adhesion molecules and cytotoxic factors in patients with tuberculosis

Human T cells and natural killer (NK) cells are major effector cells of innate immunity exerting potential immune surveillance against tuberculosis infection. CD226 is an activating receptor playing vital roles in the functions of T cells and NK cells during HIV infection and tumorigenesis. However, CD226 is a less-studied activating receptor during Mycobacterium tuberculosis (Mtb) infection. In this study, we used peripheral blood from tuberculosis patients and healthy donors to evaluate CD226 immunoregulation functions from two independent cohorts using Flow cytometry. Here, we found that a subset of T cells and NK cells that constitutively express CD226 exhibit a distinct phenotype in TB patients. In fact, the proportions of CD226⁺ and CD226^- cell subsets differ between healthy people and tuberculosis patients, and the expression of immune checkpoint molecules (TIGIT, NKG2A) and adhesion molecules (CD2, CD11a) in CD226⁺ and CD226^- subsets of T cells and NK cells exhibits special regulatory roles. Furthermore, CD226⁺ subsets produced more IFN-γ and CD107a than CD226^- subsets in tuberculosis patients. Our results imply that CD226 may be a potential predictor of disease progression and clinical efficacy in tuberculosis by mediating the cytotoxic capacity of T cells and NK cells.

Immune checkpoint modulating T cells and NK cells response to Mycobacterium tuberculosis infection

Many subversive mechanisms promote the occurrence and development of chronic infectious diseases and cancer, among which the down-regulated expression of immune-activating receptors and the enhanced expression of immune-inhibitory receptors accelerate the occurrence and progression of the disease. Recently, the use of immune checkpoint inhibitors has shown remarkable efficacy in the treatment of tumors in multiple organs. However, the expression of immune checkpoint molecules on natural killer (NK) cells by Mycobacterium tuberculosis (Mtb) infection and its impact on NK cell effector functions have been poorly studied. In this review, we focus on what is currently known about the expression of various immune checkpoints in NK cells following Mtb infection and how it alters NK cell-mediated host cytotoxicity and cytokine secretion. Unraveling the function of NK cells after the infection of host cells by Mtb is crucial for a comprehensive understanding of the innate immune mechanism of NK cells involved in tuberculosis and the evaluation of the efficacy of immunotherapies using immune checkpoint inhibitors to treat tuberculosis. In view of some similarities in the immune characteristics of T cells and NK cells, we reviewed the molecular mechanism of the interaction between T cells and Mtb, which can help us to further understand and explore the specific interaction mechanism between NK cells and Mtb.

Incubation of Lymphocytes with IL-2 Causes the Appearance of Antitumor T Cells Carrying FC, CD25, and LFA-1 on the Surface

To carry out antitumor activity against cells that have lost surface antigens, human lymphocytes must have a certain repertoire of surface proteins capable of contacting a tumor cell and inducing programmed cell death in it. In this work, we showed that activation of healthy donor cells by IL-2 cytokine within 6 days causes the appearance of FasL, CD25, and LFA-1 proteins on CD8+CD25+ T lymphocytes, and also converts the LFA-1 protein into an active form having a high affinity for its target, ICAM-1 integrin. The appearance of these proteins on the surface of this subpopulation of lymphocytes allows them to induce programmed cell death in HLA-negative tumor cells.

Selective ATM inhibition augments radiation-induced inflammatory signaling and cancer cell death

Over half of all cancer patients undergo radiation therapy but there is an unmet need for more efficacious combination strategies with molecular targeted drugs. DNA damage response has emerged as an important intervention point for improving anti-tumor effects of radiation and several inhibitors are currently in development. Ataxia telangiectasia mutated (ATM) kinase is a key regulator of cellular response to DNA double strand breaks and a potential target for radiosensitization. We recently reported two new potent and selective ATM inhibitors, M3541 and M4076, that effectively sensitize cancer cells to radiation and regress human xenografts in clinically relevant animal models. Here, we dive deeper into the cellular events in irradiated cancer cells exposed to ATM inhibitors. Suppression of ATM activity inhibited radiation-induced ATM signaling and abrogated G1 checkpoint activation resulting in enhanced cell death. Our data indicated that entry into mitosis with gross structural abnormalities in multiple chromosomes is the main mechanism behind the increased cell killing. Misalignment and mis-segregation led to formation of multiple micronuclei and robust activation of the interferon response and inflammatory signaling via the cGAS/STING/TBK1 pathway. Cancer cells exposed to radiation in the presence of M3541 were more susceptible to killing in co-culture with NK cells from healthy donors. In addition, strong upregulation of PD-L1 expression was observed in the surviving irradiated cancer cells exposed to M3541. Simultaneous activation of the STING pathway and PD-L1 suggested that combination of radiation, ATM inhibitors and PD-L1 targeted therapy may offer a novel approach to radio-immunotherapy of locally advanced tumors.

Receptors of immune cells mediates recognition for tumors

Over the last few decades, the immune system has been steered toward eradication of cancer cells with the help of cancer immunotherapy. T cells, B cells, monocytes/macrophages, dendritic cells, T-reg cells, and natural killer (NK) cells are some of the numerous immune cell types that play a significant part in cancer cell detection and reduction of inflammation, and the antitumor response. Briefly stated, chimeric antigen receptors, adoptive transfer and immune checkpoint modulators are currently the subjects of research focus for successful immunotherapy-based treatments for a variety of cancers. This chapter discusses ongoing investigations on the mechanisms and recent developments by which receptors of immune cells especially that of lymphocytes and monocytes/macrophages regulate the detection of immune system leading to malignancies. We will also be looking into the treatment strategies based on these mechanisms.

Identification of a novel mechanism for LFA-1 organization during NK cytolytic response

The elimination of transformed and viral infected cells by natural killer (NK) cells requires a specialized junction between NK and target cells, denominated immunological synapse (IS). After initial recognition, the IS enables the directed secretion of lytic granules content into the susceptible target cell. The lymphocyte function-associated antigen (LFA)-1 regulates NK effector function by enabling NK-IS assembly and maturation. The pathways underlying LFA-1 accumulation at the IS in NK cells remained uncharacterized. A kinase anchoring protein 350 (AKAP350) is a centrosome/Golgi-associated protein, which, in T cells, participates in LFA-1 activation by mechanisms that have not been elucidated. We first evaluated AKAP350 participation in NK cytolytic activity. Our results showed that the decrease in AKAP350 levels by RNA interference (AKAP350KD) inhibited NK-YTS cytolytic activity, without affecting conjugate formation. The impairment of NK effector function in AKAP350KD cells correlated with decreased LFA-1 clustering and defective IS maturation. AKAP350KD cells that were exclusively activated via LFA-1 showed impaired LFA-1 organization and deficient lytic granule translocation as well. In NK AKAP350KD cells, activation signaling through Vav1 was preserved up to 10 min of interaction with target cells, but significantly decreased afterwards. Experiments in YTS and in ex vivo NK cells identified an intracellular pool of LFA-1, which partially associated with the Golgi apparatus and, upon NK activation, redistributed to the IS in an AKAP350-dependent manner. The analysis of Golgi organization indicated that the decrease in AKAP350 expression led to the disruption of the Golgi integrity in NK cells. Alteration of Golgi function by BFA treatment or AKAP350 delocalization from this organelle also led to impaired LFA-1 localization at the IS. Therefore, this study characterizes AKAP350 participation in the modulation of NK effector function, revealing the existence of a Golgi-dependent trafficking pathway for LFA-1, which is relevant for LFA-1 organization at NK-lytic IS.

IRF2 is required for development and functional maturation of human NK cells

Natural killer (NK) cells are cytotoxic and cytokine-producing lymphocytes that play an important role in the first line of defense against malignant or virus-infected cells. A better understanding of the transcriptional regulation of human NK cell differentiation is crucial to improve the efficacy of NK cell-mediated immunotherapy for cancer treatment. Here, we studied the role of the transcription factor interferon regulatory factor (IRF) 2 in human NK cell differentiation by stable knockdown or overexpression in cord blood hematopoietic stem cells and investigated its effect on development and function of the NK cell progeny. IRF2 overexpression had limited effects in these processes, indicating that endogenous IRF2 expression levels are sufficient. However, IRF2 knockdown greatly reduced the cell numbers of all early differentiation stages, resulting in decimated NK cell numbers. This was not caused by increased apoptosis, but by decreased proliferation. Expression of IRF2 is also required for functional maturation of NK cells, as the remaining NK cells after silencing of IRF2 had a less mature phenotype and showed decreased cytotoxic potential, as well as a greatly reduced cytokine secretion. Thus, IRF2 plays an important role during development and functional maturation of human NK cells.

LFA-1/ ICAM-1 promotes NK cell cytotoxicity associated with the pathogenesis of ocular toxoplasmosis in murine model

Ocular toxoplasmosis (OT) is one of the most common causes of posterior uveitis. However, the pathogenic mechanisms of OT have not been well elucidated. Here, we used C57BL/6 (B6) mice to establish OT by peroral infection with 20 cysts of the TgCtWh6 strain, and severe ocular damage was observed by histopathological analysis in the eyes of infected mice. RNA-sequencing results showed that infection with T. gondii increased the expression of the NK-mediated cytotoxicity gene pathway at Day 30 after ocular T. gondii infection. Both NK-cell and CD49a+ NK-cell subsets are increased in ocular tissues, and the expression levels of LFA-1 in NK cells and ICAM-1 in the OT murine model were upregulated upon infection. Furthermore, inhibition of the interaction between LFA-1 and ICAM-1 with lifitegrast, a novel small molecule integrin antagonist, inhibited the protein expression of LFA-1 and ICAM-1 in murine OT and NK cells, improved the pathology of murine OT and influenced the secretion of cytokines in the OT murine model. In conclusion, the interaction between LFA-1 and ICAM-1 plays a role in the early regulation of the CD49a+ NK-cell proportion in an OT murine model. LFA-1/ ICAM-1 may be a key molecule in the pathogenesis of OT, and may provide new insights for potential immunotherapy.

Gut microbiota composition in colorectal cancer patients is genetically regulated

The risk of colorectal cancer (CRC) depends on environmental and genetic factors. Among environmental factors, an imbalance in the gut microbiota can increase CRC risk. Also, microbiota is influenced by host genetics. However, it is not known if germline variants influence CRC development by modulating microbiota composition. We investigated germline variants associated with the abundance of bacterial populations in the normal (non-involved) colorectal mucosa of 93 CRC patients and evaluated their possible role in disease. Using a multivariable linear regression, we assessed the association between germline variants identified by genome wide genotyping and bacteria abundances determined by 16S rRNA gene sequencing. We identified 37 germline variants associated with the abundance of the genera Bacteroides, Ruminococcus, Akkermansia, Faecalibacterium and Gemmiger and with alpha diversity. These variants are correlated with the expression of 58 genes involved in inflammatory responses, cell adhesion, apoptosis and barrier integrity. Genes and bacteria appear to be involved in the same processes. In fact, expression of the pro-inflammatory genes GAL, GSDMD and LY6H was correlated with the abundance of Bacteroides, which has pro-inflammatory properties; abundance of the anti-inflammatory genus Faecalibacterium correlated with expression of KAZN, with barrier-enhancing functions. Both the microbiota composition and local inflammation are regulated, at least partially, by the same germline variants. These variants may regulate the microenvironment in which bacteria grow and predispose to the development of cancer. Identification of these variants is the first step to identifying higher-risk individuals and proposing tailored preventive treatments that increase beneficial bacterial populations.

Identification of Immune-Associated Genes in Diagnosing Aortic Valve Calcification With Metabolic Syndrome by Integrated Bioinformatics Analysis and Machine Learning

Background

Immune system dysregulation plays a critical role in aortic valve calcification (AVC) and metabolic syndrome (MS) pathogenesis. The study aimed to identify pivotal diagnostic candidate genes for AVC patients with MS.

Methods

We obtained three AVC and one MS dataset from the gene expression omnibus (GEO) database. Identification of differentially expressed genes (DEGs) and module gene via Limma and weighted gene co-expression network analysis (WGCNA), functional enrichment analysis, protein–protein interaction (PPI) network construction, and machine learning algorithms (least absolute shrinkage and selection operator (LASSO) regression and random forest) were used to identify candidate immune-associated hub genes for diagnosing AVC with MS. To assess the diagnostic value, the nomogram and receiver operating characteristic (ROC) curve were developed. Finally, immune cell infiltration was created to investigate immune cell dysregulation in AVC.

Results

The merged AVC dataset included 587 DEGs, and 1,438 module genes were screened out in MS. MS DEGs were primarily enriched in immune regulation. The intersection of DEGs for AVC and module genes for MS was 50, which were mainly enriched in the immune system as well. Following the development of the PPI network, 26 node genes were filtered, and five candidate hub genes were chosen for nomogram building and diagnostic value evaluation after machine learning. The nomogram and all five candidate hub genes had high diagnostic values (area under the curve from 0.732 to 0.982). Various dysregulated immune cells were observed as well.

Conclusion

Five immune-associated candidate hub genes (BEX2, SPRY2, CXCL16, ITGAL, and MORF4L2) were identified, and the nomogram was constructed for AVC with MS diagnosis. Our study could provide potential peripheral blood diagnostic candidate genes for AVC in MS patients.

Natural killer cells have a synergistic anti-tumor effect in combination with chemoradiotherapy against head and neck cancer

BACKGROUND

The use of natural killer (NK) cells is a promising approach in the field of cancer immunotherapy; however, combination treatments are required to enhance the effects of NK cell immunotherapy. In this study, we assessed the potential of irradiation and cisplatin as a chemoradiotherapy (CRT) regimen to augment the effects of NK cell immunotherapy in head and neck squamous cell carcinoma (HNSCC).

METHODS

NK cells were expanded using our recently established K562-OX40 ligand and membrane-bound interleukin (IL)-18 and IL-21 feeder cells in the presence of IL-2/IL-15 from peripheral blood of healthy donors.

RESULTS

The results showed an increase in the purity of NK cells and expression of activation markers such as NKG2D and lymphocyte function-associated antigen 1 during the expansion process, which is positively correlated to the NK cell infiltration and overall survival in patients with HNSCC. CRT induced NK cell activation ligand (ULBP2) and adhesion molecules (ICAM-1, -2 and -3) on HNSCC, leading to enhanced cytotoxicity of NK cells against HNSCC.

CONCLUSIONS

Our findings suggest that the NK cells have a potent anti-tumor effect in combination with CRT against HNSCC.

Value of a Signature of Immune-Related Genes in Predicting the Prognosis of Melanoma and Its Responses to Immune Checkpoint Blocker Therapies

Melanoma is becoming increasingly common worldwide, with high rates of transformation into malignancy compared to other skin lesions. The prognosis of patients with melanoma at an advanced stage is highly unsatisfying despite the development of immunotherapy, target therapy, or combinative therapy. The major barrier to exploiting immune checkpoint therapies and achieving the best benefits clinically is resistance that can easily develop if regimens are not selected appropriately. In this study, we investigated the possibility of using immune-related genes to predict patient survival and their responses to immune checkpoint blocker therapies with the expression profiles available at The Cancer Genome Atlas (TCGA) Program plus expression data from the Gene Expression Omnibus (GEO) for validation. A five gene signature that is highly correlated with the local infiltration of cytotoxic lymphocytes in the tumor microenvironment was identified, and a scoring model was developed with stepwise regression after multivariate Cox analyses. The score calculated strongly correlates with Breslow depth, and this model effectively predicts the prognosis of patients with melanoma, whether primary or metastasized. It also depicts the heterogenous immune-related nature of melanoma by revealing different predicted responses to immune checkpoint blocker therapies through its correlation to tumor immune dysfunction and exclusion (TIDE) score.

From CD16a Biology to Antibody-Dependent Cell-Mediated Cytotoxicity Improvement

Antibody-dependent cell-mediated cytotoxicity (ADCC) is a potent cytotoxic mechanism that is mainly mediated in humans by natural killer (NK) cells. ADCC mediates the clinical benefit of several widely used cytolytic monoclonal antibodies (mAbs), and increasing its efficacy would improve cancer immunotherapy. CD16a is a receptor for the Fc portion of IgGs and is responsible to trigger NK cell-mediated ADCC. The knowledge of the mechanism of action of CD16a gave rise to several strategies to improve ADCC, by working on either the mAbs or the NK cell. In this review, we give an overview of CD16a biology and describe the latest strategies employed to improve antibody-dependent NK cell cytotoxicity.

Natural killer cell-based strategies for immunotherapy of cancer

Natural killer (NK) cells are a family of lymphocytes with a natural ability to kill infected, harmed, or malignantly transformed cells. As these cells are part of the innate immunity, the cytotoxic mechanisms are activated upon recognizing specific patterns without prior antigen sensitization. This recognition is crucial for NK cell function in the maintenance of homeostasis and immunosurveillance. NK cells not only act directly toward malignant cells but also participate in the complex immune response by producing cytokines or cross-talk with other immune cells. Cancer may be seen as a break of all immune defenses when malignant cells escape the immunity and invade surrounding tissues creating a microenvironment supporting tumor progression. This process may be reverted by intervening immune response with immunotherapy, which may restore immune recognition. NK cells are important effector cells for immunotherapy. They may be used for adoptive cell transfer, genetically modified with chimeric antigen receptors, or triggered with appropriate antibodies and other antibody-fragment-based recombinant therapeutic proteins tailored specifically for NK cell engagement. NK cell receptors, responsible for target recognition and activation of cytotoxic response, could also be targeted in immunotherapy, for example, by various bi-, tri-, or multi-specific fusion proteins designed to bridge the gap between tumor markers present on target cells and activation receptors expressed on NK cells. However, this kind of immunoactive therapeutics may be developed only with a deep functional and structural knowledge of NK cell receptor: ligand interactions. This review describes the recent developments in the fascinating protein-engineering field of NK cell immunotherapeutics.

Systematic analysis of prognostic significance, functional enrichment and immune implication of STK10 in acute myeloid leukemia

Background

Despite deeper understanding of the genetic landscape of acute myeloid leukemia (AML), the improvement of survival is still a great challenge. STK10 is overexpressed in several cancers with functions varying according to cancer types. But the functions of STK10 in AML has never been reported.

Methods

We analyzed the expression, prognosis and potential functions of STK10 utilizing public web servers. Metascape and the String database were used for functional and protein–protein interaction analyses.

Results

We found STK10 was enriched in blood & immune cells and overexpressed in AML. High STK10 expression was associated with poor overall survival, which was also identified in the subgroups of patients ≤ 60 years old and patients with non-high-risk cytogenetics. We demonstrated genes associated with STK10 were enriched in blood, spleen and bone marrow, influencing the immune function and biological process of AML. ITGB2 and ITGAM might directly interact with STK10 and were associated with poor prognosis. Besides, STK10 was associated with the infiltration of immune cells and immune checkpoints, like HLA-E, CD274 and GAL-9.

Conclusions

The present study was the original description of STK10 in AML and set the stage for developing STK10 as a new prognostic marker or therapeutic target for AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01251-7.

ITGAL as a Prognostic Biomarker Correlated With Immune Infiltrates in Gastric Cancer

Integrin alpha L (ITGAL) is a member of the integrin family in which the abnormal expression is linked with carcinogenesis and immune regulation. However, the relation between ITGAL and the prognosis of gastric cancer (GC) and tumor-infiltrating lymphocytes (TILs) are not well understood. The differential expressions of ITGAL in human tumors and the clinical prognosis in GC were systematically analyzed via multiple databases including Gene Expression Profiling Interaction Analysis (GEPIA), UALCAN, Tumor Immune Estimation Resource (TIMER), and Kaplan–Meier (KM) plotter. TIMER, GEPIA, and TISIDB databases were used to comprehensively investigate the correlation between ITGAL and tumor infiltration immune cells. Also, further results were investigated by immunohistochemistry, qRT-PCR, and Western blot. We found that ITGAL expression in GC samples was considerably increased than in peritumor samples. Sample type, subgroup, cancer stage, lymphatic node stage, and worse survival were strongly related to high ITGAL expression. Moreover, upregulated ITGAL expression was strongly connected with immunomodulators, chemokines, and infiltrating levels of CD8+, CD4+ T cell, B cell, monocyte, neutrophil, macrophage, T-cell regulatory, NK cell, and myeloid dendritic cell in stomach adenocarcinoma (STAD). Specifically, immunohistochemistry and bioinformatic analysis showed that ITGAL expression was shown to have strong relationships with various immunological marker sets including PD1 (T-cell exhaustion marker). In conclusion, ITGAL is a prognostic biomarker for GC patients. It might regulate tumor immune microenvironment leading to poor prognosis. Furthermore, studies are essential to explore therapeutic targeting ITGAL.

Filamin A Is Required for NK Cell Cytotoxicity at the Expense of Cytokine Production via Synaptic Filamentous Actin Modulation

Natural killer (NK) cells are innate cytotoxic lymphocytes that efficiently eliminate malignant and virus-infected cells without prior activation via the directed and focused release of lytic granule contents for target cell lysis. This cytolytic process is tightly regulated at discrete checkpoint stages to ensure the selective killing of diseased target cells and is highly dependent on the coordinated regulation of cytoskeletal components. The actin-binding protein filamin crosslinks cortical actin filaments into orthogonal networks and links actin filament webs to cellular membranes to modulate cell migration, adhesion, and signaling. However, its role in the regulation of NK cell functions remains poorly understood. Here, we show that filamin A (FLNa), a filamin isoform with preferential expression in leukocytes, is recruited to the NK cell lytic synapse and is required for NK cell cytotoxicity through the modulation of conjugate formation with target cells, synaptic filamentous actin (F-actin) accumulation, and cytotoxic degranulation, but not granule polarization. Interestingly, we also find that the loss of FLNa augments the target cell-induced expression of IFN-γ and TNF-α by NK cells, correlating with enhanced activation signals such as Ca²⁺ mobilization, ERK, and NF-κB, and a delayed down-modulation of the NKG2D receptor. Thus, our results identify FLNa as a new regulator of NK cell effector functions during their decision to kill target cells through a balanced regulation of NK cell cytotoxicity vs cytokine production. Moreover, this study implicates the cross-linking/bundling of F-actin mediated by FLNa as a necessary process coordinating optimal NK effector functions.

Reactivity of NK Cells Against Ovarian Cancer Cells Is Maintained in the Presence of Calcium Phosphate Nanoparticles

Calcium phosphate nanoparticles (CaP-NPs) are biodegradable carriers that can be functionalized with biologically active molecules. As such, they are potential candidates for delivery of therapeutic molecules in cancer therapies. In this context, it is important to explore whether CaP-NPs impair the natural or therapy-induced immune cell activity against cancer cells. Therefore, in this study, we have investigated the effects of different CaP-NPs on the anti-tumor activity of natural killer (NK) cells using different ovarian cancer (OC) cell line models. We explored these interactions in coculture systems consisting of NK cells, OC cells, CaP-NPs, and therapeutic Cetuximab antibodies (anti-EGFR, ADCC-inducing antibody). Our experiments revealed that aggregated CaP-NPs can serve as artificial targets, which activate NK cell degranulation and impair ADCC directed against tumor targets. However, when CaP-NPs were properly dissolved by sonication, they did not cause substantial activation. CaP-NPs with SiO2-SH-shell induced some activation of NK cells that was not observed with polyethyleneimine-coated CaP-NPs. Addition of CaP-NPs to NK killing assays did not impair conjugation of NK with OC and subsequent tumor cytolytic NK degranulation. Therapeutic antibody coupled to functionalized CaP-NPs maintained substantial levels of antibody-dependent cellular cytotoxic activity. Our study provides a cell biological basis for the application of functionalized CaP-NPs in immunologic anti-cancer therapies.

Cathepsin X Activity Does Not Affect NK-Target Cell Synapse but Is Rather Distributed to Cytotoxic Granules

Cathepsin X is a lysosomal peptidase that is involved in tumour progression and represents a potential target for therapeutic interventions. In addition, it regulates important functions of immune cells and is implicated in the modulation of tumour cell–immune cell crosstalk. Selective cathepsin X inhibitors have been proposed as prospective antitumour agents to prevent cancer progression; however, their impact on the antitumour immune response has been overlooked. Previous studies indicate that the migration and adhesion of T cells and dendritic cells are affected by diminished cathepsin X activity. Meanwhile, the influence of cathepsin X inhibition on natural killer (NK) cell function has not yet been explored. Here, we examined the localization patterns of cathepsin X and the role of its inhibitors on the cytotoxicity of cell line NK-92, which is used for adoptive cellular immunotherapy in cancer patients. NK-92 cells depend on lymphocyte function-associated antigen 1 (LFA-1) to form stable immunoconjugates with target cells, providing, in this way, optimal cytotoxicity. Since LFA-1 is a substrate for cathepsin X activity in other types of cells, we hypothesized that cathepsin X could disturb the formation of NK-92 immunoconjugates. Thus, we employed cathepsin X reversible and irreversible inhibitors and evaluated their effects on the NK-92 cell interactions with target cells and on the NK-92 cell cytotoxicity. We show that cathepsin X inhibition does not impair stable conjugate formation or the lytic activity of NK-92 cells. Similarly, the conjugate formation between Jurkat T cells and target cells was not affected by cathepsin X activity. Unlike in previous migration and adhesion studies on T cells, in NK-92 cells cathepsin X was not co-localized with LFA-1 at the plasma membrane but was, rather, redistributed to the cytotoxic granules and secreted during degranulation.

Profiling the immune response to Mycobacterium tuberculosis Beijing family infection: a perspective from the transcriptome

Tuberculosis continues to be an important public health problem. Particularly considering Beijing-family strains of Mycobacterium tuberculosis, which have been associated with drug-resistance and hypervirulence. The Beijing-like SIT190 (BL) is the most prevalent Beijing strain in Colombia. The pathogenic mechanism and immune response against this pathogen is unknown. Thus, we compared the course of pulmonary TB in BALB/c mice infected with Classical-Beijing strain 391 and BL strain 323. The disease course was different among infected animals with Classical-Beijing and BL strain. Mice infected with BL had a 100% mortality at 45 days post-infection (dpi), with high bacillary loads and massive pneumonia, whereas infected animals with Classical-Beijing survived until 60 dpi and showed extensive pneumonia and necrosis. Lung RNA extraction was carried out at early (day 3 dpi), intermediate (day 14 dpi), and late (days 28 and 60 dpi) time points of infection. Transcriptional analysis of infected mice with Classical-Beijing showed several over-expressed genes, associated with a pro-inflammatory profile, including those for coding for CCL3 and CCL4 chemokines, both biomarkers of disease severity. Conversely, mice infected with BL displayed a profile which included the over-expression of several genes associated with immune-suppression, including Nkiras, Dleu2, and Sphk2, highlighting an anti-inflammatory milieu which would allow high bacterial replication followed by an intense inflammatory response. In summary, both Beijing strains induced a non-protective immune response which induced extensive tissue damage, BL strain induced rapidly extensive pneumonia and death, whereas Classical-Beijing strain produced slower extensive pneumonia later associated with extensive necrosis.

The Role of Matrix Metalloproteinases in Endometriosis: A Potential Target

Endometriosis is a condition that is influenced by hormones and involves stroma and glands being found outside the uterus; there are increases in proliferation, invasion, internal bleeding, and fibrosis. Matrix metalloproteinases (MMPs) have been suggested to be crucial in the progression of invasion. The MMP family includes calcium-dependent zinc-containing endopeptidases, some of which not only affect the process of cell invasion but also participate in other physiological and pathological processes, such as angiogenesis and fibrosis. MMPs act as downstream-targeted molecules and their expression can be regulated by numerous factors such as estrogen, oxidative stress, cytokines, and environmental contaminants. Given their unique roles in endometriosis, MMPs may become effective biomarkers of endometriosis in the future. In the present review, we summarize the current literature on MMPs regarding their classification, function, and potential value for endometriosis, which may contribute to our knowledge of MMPs and MMP-targeted interventions.

Kaposi's sarcoma-associated herpesvirus ubiquitin ligases downregulate cell surface expression of l-selectin

Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic etiological factor for Kaposi's sarcoma and primary effusion lymphoma in immunocompromised patients. KSHV utilizes two immune evasion E3 ubiquitin ligases, namely K3 and K5, to downregulate the expression of antigen-presenting molecules and ligands of natural killer (NK) cells in the host cells through an ubiquitin-dependent endocytic mechanism. This allows the infected cells to evade surveillance and elimination by cytotoxic lymphocytes and NK cells. The number of host cell molecular substrates reported for these ubiquitin ligases is limited. The identification of novel substrates for these ligases will aid in elucidating the mechanism underlying immune evasion of KSHV. This study demonstrated that K5 downregulated the cell surface expression of l-selectin, a C-type lectin-like adhesion receptor expressed in the lymphocytes. Tryptophan residue located at the centre of the E2-binding site in the K5 RINGv domain was essential to downregulate l-selectin expression. Additionally, the lysine residues located at the cytoplasmic tail of l-selectin were required for the K5-mediated downregulation of l-selectin. K5 promoted the degradation of l-selectin through polyubiquitination. These results suggest that K5 downregulates l-selectin expression on the cell surface by promoting polyubiquitination and ubiquitin-dependent endocytosis, which indicated that l-selectin is a novel substrate for K5. Additionally, K3 downregulated l-selectin expression. The findings of this study will aid in the elucidation of a novel immune evasion mechanism in KSHV.

SLAMF7 selectively favors degranulation to promote cytotoxicity in human NK cells

NK cells play an important role in immunity by recognizing and eliminating cells undergoing infection or malignant transformation. This role is dependent on the ability of NK cells to lyse targets cells in a perforin-dependent mechanism and by secreting inflammatory cytokines. Both effector functions are controlled by several cell surface receptors. The Signaling Lymphocyte Activation Molecule (SLAM) family of receptors plays an essential role in regulating NK cell activation. Several studies have demonstrated that SLAMF7 regulates NK cell activation. However, the molecular and cellular mechanisms by which SLAMF7 influences NK effector functions are unknown. Here, we present evidence that physiological ligation of SLAMF7 in human NK cells enhances the lysis of target cells expressing SLAMF7. This effect was dependent on the ability of SLAMF7 to promote NK cell degranulation rather than cytotoxic granule polarization or cell adhesion. Moreover, SLAMF7-dependent NK cell degranulation was predominantly dependent on PLC-γ when compared to PI3K. These data provide novel information on the cellular mechanism by which SLAMF7 regulates human NK cell activation. Finally, this study supports a model for NK cell activation where activated receptors contribute by regulating specific discrete cellular events rather than multiple cellular processes.

The Prognosis and Immune Checkpoint Blockade Efficacy Prediction of Tumor-Infiltrating Immune Cells in Lung Cancer

Backgrounds

The high morbidity and mortality of lung cancer are serious public health problems. The prognosis of lung cancer and whether to apply immune checkpoint blockade (ICB) are currently urgent problems to be solved.

Methods

Using R software, we performed Kaplan–Meier (K-M) analysis, Cox regression analysis, functional enrichment analysis, Spearman correlation analysis, and the single-sample gene set enrichment analysis.

Results

On the Tumor IMmune Estimation Resource (TIMER2.0) website, we calculated the abundance of tumor-infiltrating immune cells (TIICs) of lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) patients. B cell and myeloid dendritic cell (DC1) were independent prognostic factors for LUAD and LUSC patients, respectively. Enrichment analysis confirmed that genes highly related to B cell or DC1 were closely related to the immune activation of lung cancer patients. In terms of adaptive immune resistance markers, CD8A, CD8B, immunomodulators (immunostimulants, major histocompatibility complex, receptors, and chemokines), immune-related pathways, tumor microenvironment score, and TIICs, high B cell/DC1 infiltration tissue was inflamed and immune-activated and might benefit more from the ICB. Genes most related to B cell [CD19, toll-like receptor 10 (TLR10), and Fc receptor-like A (FCRLA)] and DC1 (ITGB2, LAPTM5, and SLC7A7) partially clarified the roles of B cell/DC1 in predicting ICB efficacy. Among the 186 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, there were three and four KEGG pathways, which partially explained the molecular mechanisms by which B cell and DC1 simultaneously predicted the prognosis and efficacy of immunotherapy, respectively. Among five immune subtypes, the abundance of B cell/DC1 and expression of six hub genes were higher in immune C2, C3, and C6.

Conclusion

B cell and DC1 could predict the prognosis and ICB efficacy of LUAD and LUSC patients, respectively. The six hub genes and seven KEGG pathways might be novel immunotherapy targets. Immune C2, C3, and C6 subtypes of lung cancer patients might benefit more from ICB therapy.

ICAM-1 and ICAM-2 Are Differentially Expressed and Up-Regulated on Inflamed Pulmonary Epithelium, but Neither ICAM-2 nor LFA-1: ICAM-1 Are Required for Neutrophil Migration Into the Airways In Vivo

Neutrophil migration into the airways is an important process to fight infection and is mediated by cell adhesion molecules. The intercellular adhesion molecules, ICAM-1 (CD54) and ICAM-2 (CD102) are known ligands for the neutrophil integrins, lymphocyte function associated antigen (LFA)-1 (αLβ2; CD11a/CD18), and macrophage-1 antigen (Mac-1;αMβ2;CD11b/CD18) and are implicated in leukocyte migration into the lung. However, it is ill-defined how neutrophils exit the lung and the role for ICAMs in trans-epithelial migration (TEpM) across the bronchial or alveolar epithelium. We found that human and murine alveolar epithelium expressed ICAM-1, whilst the bronchial epithelium expressed ICAM-2, and both were up-regulated during inflammatory stimulation in vitro and in inflammatory lung diseases such as cystic fibrosis. Although β2 integrins interacting with ICAM-1 and -2 mediated neutrophil migration across human bronchial epithelium in vitro, neither ICAM-2 nor LFA-1 binding of ICAM-1 mediated murine neutrophil migration into the lung or broncho-alveolar space during LPS-induced inflammation in vivo. Furthermore, TEpM of neutrophils themselves resulted in increased epithelial junctional permeability and reduced barrier function in vitro. This suggests that although β2 integrins interacting with ICAMs may regulate low levels of neutrophil traffic in healthy lung or early in inflammation when the epithelial barrier is intact; these interactions may be redundant later in inflammation when epithelial junctions are disrupted and no longer limit TEpM.

The Role of microRNAs in NK Cell Development and Function

The clinical use of natural killer (NK) cells is at the forefront of cellular therapy. NK cells possess exceptional antitumor cytotoxic potentials and can generate significant levels of proinflammatory cytokines. Multiple genetic manipulations are being tested to augment the anti-tumor functions of NK cells. One such method involves identifying and altering microRNAs (miRNAs) that play essential roles in the development and effector functions of NK cells. Unique miRNAs can bind and inactivate mRNAs that code for cytotoxic proteins. MicroRNAs, such as the members of the Mirc11 cistron, downmodulate ubiquitin ligases that are central to the activation of the obligatory transcription factors responsible for the production of inflammatory cytokines. These studies reveal potential opportunities to post-translationally enhance the effector functions of human NK cells while reducing unwanted outcomes. Here, we summarize the recent advances made on miRNAs in murine and human NK cells and their relevance to NK cell development and functions.

NK cells integrate signals over large areas when building immune synapses but require local stimuli for degranulation

Immune synapses are large-scale, transient molecular assemblies that serve as platforms for antigen presentation to B and T cells and for target recognition by cytotoxic T cells and natural killer (NK) cells. The formation of an immune synapse is a tightly regulated, stepwise process in which the cytoskeleton, cell surface receptors, and intracellular signaling proteins rearrange into supramolecular activation clusters (SMACs). We generated artificial immune synapses (AIS) consisting of synthetic and natural ligands for the NK cell-activating receptors LFA-1 and CD16 by microcontact printing the ligands into circular-shaped SMAC structures. Live-cell imaging and analysis of fixed human NK cells in this reductionist system showed that the spatial distribution of activating ligands influenced the formation, stability, and outcome of NK cell synapses. Whereas engagement of LFA-1 alone promoted synapse initiation, combined engagement of LFA-1 and CD16 was required for the formation of mature synapses and degranulation. Organizing LFA-1 and CD16 ligands into donut-shaped AIS resulted in fewer long-lasting, symmetrical synapses compared to dot-shaped AIS. NK cells spreading evenly over either AIS shape exhibited similar arrangements of the lytic machinery. However, degranulation only occurred in regions containing ligands that therefore induced local signaling, suggesting the existence of a late checkpoint for degranulation. Our results demonstrate that the spatial organization of ligands in the synapse can affect its outcome, which could be exploited by target cells as an escape mechanism.

The effect of anti‑HLA class I antibodies on the immunological properties of human glomerular endothelial cells and their modification by mTOR inhibition or GCN2 kinase activation

In antibody‑mediated rejection (ABMR), the graft endothelium is at the forefront of the kidney transplant against the assault from the recipient's humoral immune system, and is a target of the latter. The present study investigated the effect of antibodies against human leukocyte antigen (HLA) class I (anti‑HLAI) on the immunological properties of human glomerular endothelial cells. Additionally, the effect of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) inhibitor (everolimus), or the general control nonderepressible 2 kinase (GCN2K) activator (halofuginone) on anti‑HLAI antibody‑mediated alterations was assessed. Cell integrity was examined, an lactate dehydrogenase (LDH) release assay was performed and cleaved caspase‑3 levels were determined. Furthermore, cell proliferation was analyzed by performing a bromodeoxyuridine assay and the cellular proteins involved in signal transduction or immune effector mechanisms were assessed via western blotting. IL‑8, monocyte chemoattractive protein‑1 (MCP‑1), von Willebrand factor (vWF) and transforming growth factor‑beta 1 (TGF‑β1) were assayed via ELISA. The results revealed that anti‑HLAI triggered integrin signaling, activated mTOR and GCN2K, preserved cell integrity and promoted cell proliferation. Additionally, by increasing intercellular adhesion molecule 1 (ICAM‑1), HLA‑DR, IL‑8 and MCP‑1 levels, anti‑HLAI enhanced the ability of immune cells to interact with endothelial cells thus facilitating graft rejection. Contrarily, by upregulating CD46 and CD59, anti‑HLAI rendered the endothelium less vulnerable to complement‑mediated injury. Finally, by enhancing vWF and TGF‑β1, anti‑HLAI may render the endothelium prothrombotic and facilitate fibrosis and graft failure, respectively. According to our results, mTORC1 inhibition and GCN2K activation may prove useful pharmaceutical targets, as they prevent cell proliferation and downregulate ICAM‑1, IL‑8, MCP‑1 and TGF‑β1. mTORC1 inhibition also decreases vWF.

Constitutive activation of WASp leads to abnormal cytotoxic cells with increased granzyme B and degranulation response to target cells

X-linked neutropenia (XLN) is caused by gain-of-function mutations in the actin regulator Wiskott-Aldrich Syndrome protein (WASp). XLN patients have reduced numbers of cytotoxic cells in peripheral blood; however, their capacity to kill tumor cells remains to be determined. Here, we examined NK and T cells from 2 patients with XLN harboring the activating WASp^L270P mutation. XLN patient NK and T cells had increased granzyme B content and elevated degranulation and IFN-γ production when compared with healthy control cells. Murine WASp^L272P NK and T cells formed stable synapses with YAC-1 tumor cells and anti-CD3/CD28–coated beads, respectively. WASp^L272P mouse T cells had normal degranulation and cytokine response whereas WASp^L272P NK cells showed an enhanced response. Imaging experiments revealed that while WASp^L272P CD8⁺ T cells had increased accumulation of actin upon TCR activation, WASp^L272P NK cells had normal actin accumulation at lytic synapses triggered through NKp46 signaling but had impaired response to lymphocyte function associated antigen-1 engagement. When compared with WT mice, WASp^L272P mice showed reduced growth of B16 melanoma and increased capacity to reject MHC class I–deficient cells. Together, our data suggest that cytotoxic cells with constitutively active WASp have an increased capacity to respond to and kill tumor cells.

Molecular Aspects of Volatile Anesthetic-Induced Organ Protection and Its Potential in Kidney Transplantation

Ischemia reperfusion injury (IRI) is inevitable in kidney transplantation and negatively impacts graft and patient outcome. Reperfusion takes place in the recipient and most of the injury following ischemia and reperfusion occurs during this reperfusion phase; therefore, the intra-operative period seems an attractive window of opportunity to modulate IRI and improve short- and potentially long-term graft outcome. Commonly used volatile anesthetics such as sevoflurane and isoflurane have been shown to interfere with many of the pathophysiological processes involved in the injurious cascade of IRI. Therefore, volatile anesthetic (VA) agents might be the preferred anesthetics used during the transplantation procedure. This review highlights the molecular and cellular protective points of engagement of VA shown in in vitro studies and in vivo animal experiments, and the potential translation of these results to the clinical setting of kidney transplantation.

The Role of the Cytoskeleton in Regulating the Natural Killer Cell Immune Response in Health and Disease: From Signaling Dynamics to Function

Natural killer (NK) cells are innate lymphoid cells, which play key roles in elimination of virally infected and malignant cells. The balance between activating and inhibitory signals derived from NK surface receptors govern the NK cell immune response. The cytoskeleton facilitates most NK cell effector functions, such as motility, infiltration, conjugation with target cells, immunological synapse assembly, and cytotoxicity. Though many studies have characterized signaling pathways that promote actin reorganization in immune cells, it is not completely clear how particular cytoskeletal architectures at the immunological synapse promote effector functions, and how cytoskeletal dynamics impact downstream signaling pathways and activation. Moreover, pioneering studies employing advanced imaging techniques have only begun to uncover the architectural complexity dictating the NK cell activation threshold; it is becoming clear that a distinct organization of the cytoskeleton and signaling receptors at the NK immunological synapse plays a decisive role in activation and tolerance. Here, we review the roles of the actin cytoskeleton in NK cells. We focus on how actin dynamics impact cytolytic granule secretion, NK cell motility, and NK cell infiltration through tissues into inflammatory sites. We will also describe the additional cytoskeletal components, non-muscle Myosin II and microtubules that play pivotal roles in NK cell activity. Furthermore, special emphasis will be placed on the role of the cytoskeleton in assembly of immunological synapses, and how mutations or downregulation of cytoskeletal accessory proteins impact NK cell function in health and disease.

Inability of granule polarization by NK cells defines tumor resistance and can be overcome by CAR or ADCC mediated targeting

Background

On encountering a susceptible target, natural killer (NK) cells mediate cytotoxicity through highly regulated steps of directed degranulation. Cytotoxic granules converge at the microtubule organizing center and are polarized toward the immunological synapse (IS), followed by granule exocytosis. NK cell retargeting by chimeric antigen receptors (CARs) or mAbs represents a promising strategy for overcoming tumor cell resistance. However, little is known about the lytic granule dynamics of such retargeted NK cells toward NK-cell-resistant tumors.

Methods

Here, we used spinning disk confocal microscopy for live-cell imaging to analyze granule-mediated NK cell cytotoxicity in ErbB2-targeted CAR-expressing NK-92 cells (NK-92/5.28.z) and high-affinity FcR transgenic NK-92 cells plus Herceptin toward ErbB2-positive breast cancer cells (MDA-MB-453), which are resistant to parental NK-92.

Results

Unmodified NK-92 cells cocultured with resistant cancer cells showed stable conjugate formation and granule clustering, but failed to polarize granules to the IS. In contrast, retargeting by CAR or FcR+Herceptin toward the MDA-MB-453 cells enabled granule polarization to the IS, resulting in highly effective cytotoxicity. We found that in NK-92 the phosphoinositide 3-kinase pathway was activated after contact with resistant MDA-MB-453, while phospholipase C-γ (PLCγ) and mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) were not activated. In contrast, retargeting by CAR or antibody-dependent cell-mediated cytotoxicity (ADCC) provided the missing PLCγ and MEK/ERK signals.

Conclusions

These observations suggest that NK cells can create conjugates with resistant cancer cells and respond by granule clustering, but the activation signals are insufficient to induce granule polarization and consequent release of lytic enzymes. Retargeting by CAR and/or the FcR/mAb (ADCC) axis provide the necessary signals, leading to granule polarization and thereby overcoming tumor cell resistance.

Keywords: NK cells, NK-92, haNK, ADCC, Chimeric Antigen Receptor (CAR), breast cancer, cancer immunotherapy, live-cell imaging, granule polarization

Tumor microenvironment related novel signature predict lung adenocarcinoma survival

Background

Lung adenocarcinoma (LUAD) is the most common histological type of lung cancers, which is the primary cause of cancer‐related mortality worldwide. Growing evidence has suggested that tumor microenvironment (TME) plays a pivotal role in tumorigenesis and progression. Hence, we investigate the correlation of TME related genes with LUAD prognosis.

Method

The information of LUAD gene expression data was obtained from The Cancer Genome Atlas (TCGA). According to their immune/stromal scores calculated by the ESTIMATE algorithm, differentially expressed genes (DEGs) were identified. Then, we performed univariate Cox regression analysis on DEGs to obtain genes that are apparently bound up with LUAD survival (SurGenes). Functional annotation and protein-protein interaction (PPI) was also conducted on SurGenes. By validating the SurGenes with data sets of lung cancer from the Gene Expression Omnibus (GEO), 106 TME related SurGenes were generated. Further, intersection analysis was executed between the 106 TME related SurGenes and hub genes from PPI network, PTPRC and CD19 were obtained. Gene Set Enrichment Analysis and CIBERSORT analysis were performed on PTPRC and CD19. Based on the TCGA LUAD dataset, we conducted factor analysis and Step-wise multivariate Cox regression analysis for 106 TME related SurGenes to construct the prognostic model for LUAD survival prediction. The LUAD dataset in GEO (GSE68465) was used as the testing dataset to confirm the prognostic model. Multivariate Cox regression analysis was used between risk score from the prognostic model and clinical parameters.

Result

A total of 106 TME related genes were collected in our research totally, which were markedly correlated with the overall survival (OS) of LUAD patient. Bioinformatics analysis suggest them mainly concentrated on immune response, cell adhesion, and extracellular matrix. More importantly, among 106 TME related SurGenes, PTPRC and CD19 were highly interconnected nodes among PPI network and correlated with immune activity, exhibiting significant prognostic potential. The prognostic model was a weighted linear combination of the 106 genes, by which the low-OS LUAD samples could be separated from the high-OS samples with success. This model was also able to rebustly predict the situation of survival (training set: p-value < 0.0001, area under the curve (AUC) = 0.649; testing set: p-value = 0.0009, AUC = 0.617). By combining with clinical parameters, the prognostic model was optimized. The AUC achieved 0.716 for 3 year and 0.699 for 5 year.

Conclusion

A series of TME-related prognostic genes were acquired in this research, which could reflect immune disorders within TME, and PTPRC and CD19 show the potential to be an indicator for LUAD prognosis and tumor microenvironment modulation. The prognostic model constructed base on those prognostic genes presented a high predictive ability, and may have clinical implications in the overall survival prediction of LUAD.

An optimal control approach for enhancing natural killer cells' secretion of cytolytic molecules

Natural killer (NK) cells are immune effector cells that can detect and lyse cancer cells. However, NK cell exhaustion, a phenotype characterized by reduced secretion of cytolytic models upon serial stimulation, limits the NK cell's ability to lyse cells. In this work, we investigated in silico strategies that counteract the NK cell's reduced secretion of cytolytic molecules. To accomplish this goal, we constructed a mathematical model that describes the dynamics of the cytolytic molecules granzyme B (GZMB) and perforin-1 (PRF1) and calibrated the model predictions to published experimental data using a Bayesian parameter estimation approach. We applied an information-theoretic approach to perform a global sensitivity analysis, from which we found that the suppression of phosphatase activity maximizes the secretion of GZMB and PRF1. However, simply reducing the phosphatase activity is shown to deplete the cell's intracellular pools of GZMB and PRF1. Thus, we added a synthetic Notch (synNotch) signaling circuit to our baseline model as a method for controlling the secretion of GZMB and PRF1 by inhibiting phosphatase activity and increasing production of GZMB and PRF1. We found that the optimal synNotch system depends on the frequency of NK cell stimulation. For only a few rounds of stimulation, the model predicts that inhibition of phosphatase activity leads to more secreted GZMB and PRF1; however, for many rounds of stimulation, the model reveals that increasing production of the cytolytic molecules is the optimal strategy. In total, we developed a mathematical framework that provides actionable insight into engineering robust NK cells for clinical applications.

The Tumor Microenvironment-A Metabolic Obstacle to NK Cells' Activity

NK cells have unique capabilities of recognition and destruction of tumor cells, without the requirement for prior immunization of the host. Maintaining tolerance to healthy cells makes them an attractive therapeutic tool for almost all types of cancer. Unfortunately, metabolic changes associated with malignant transformation and tumor progression lead to immunosuppression within the tumor microenvironment, which in turn limits the efficacy of various immunotherapies. In this review, we provide a brief description of the metabolic changes characteristic for the tumor microenvironment. Both tumor and tumor-associated cells produce and secrete factors that directly or indirectly prevent NK cell cytotoxicity. Here, we depict the molecular mechanisms responsible for the inhibition of immune effector cells by metabolic factors. Finally, we summarize the strategies to enhance NK cell function for the treatment of tumors.

Escape of tumor cells from the NK cell cytotoxic activity

In recent years, NK cells, initially identified as potent cytotoxic effector cells, have revealed an unexpected complexity, both at phenotypic and functional levels. The discovery of different NK cell subsets, characterized by distinct gene expression and phenotypes, was combined with the characterization of the diverse functions NK cells can exert, not only as circulating cells, but also as cells localized or recruited in lymphoid organs and in multiple tissues. Besides the elimination of tumor and virus-infected cells, these functions include the production of cytokines and chemokines, the regulation of innate and adaptive immune cells, the influence on tissue homeostasis. In addition, NK cells display a remarkable functional plasticity, being able to adapt to the environment and to develop a kind of memory. Nevertheless, the powerful cytotoxic activity of NK cells remains one of their most relevant properties, particularly in the antitumor response. In this review, the process of tumor cell recognition and killing mediated by NK cells, starting from the generation of cytolytic granules and recognition of target cell, to the establishment of the NK cell immunological synapse, the release of cytotoxic molecules, and consequent tumor cell death is described. Next, the review focuses on the heterogeneous mechanisms, either intrinsic to tumors or induced by the tumor microenvironment, by which cancer cells can escape the NK cell-mediated attack.

Enhancing network activation in natural killer cells: predictions from in silico modeling

Natural killer (NK) cells are part of the innate immune system and are capable of killing diseased cells. As a result, NK cells are being used for adoptive cell therapies for cancer patients. The activation of NK cell stimulatory receptors leads to a cascade of intracellular phosphorylation reactions, which activates key signaling species that facilitate the secretion of cytolytic molecules required for cell killing. Strategies that maximize the activation of such intracellular species can increase the likelihood of NK cell killing upon contact with a cancer cell and thereby improve efficacy of NK cell-based therapies. However, due to the complexity of intracellular signaling, it is difficult to deduce a priori which strategies can enhance species activation. Therefore, we constructed a mechanistic model of the CD16, 2B4 and NKG2D signaling pathways in NK cells to simulate strategies that enhance signaling. The model predictions were fit to published data and validated with a separate dataset. Model simulations demonstrate strong network activation when the CD16 pathway is stimulated. The magnitude of species activation is most sensitive to the receptor's initial concentration and the rate at which the receptor is activated. Co-stimulation of CD16 and NKG2D in silico required fewer ligands to achieve half-maximal activation than other combinations, suggesting co-stimulating these pathways is most effective in activating the species. We applied the model to predict the effects of perturbing the signaling network and found two strategies that can potently enhance network activation. When the availability of ligands is low, it is more influential to engineer NK cell receptors that are resistant to proteolytic cleavage. In contrast, for high ligand concentrations, inhibiting phosphatase activity leads to sustained species activation. The work presented here establishes a framework for understanding the complex, nonlinear aspects of NK cell signaling and provides detailed strategies for enhancing NK cell activation.

RIAM-VASP Module Relays Integrin Complement Receptors in Outside-In Signaling Driving Particle Engulfment

The phagocytic integrins and complement receptors α_Mβ₂/CR3 and α_Xβ₂/CR4 are classically associated with the phagocytosis of iC3b-opsonized particles. The activation of this receptor is dependent on signals derived from other receptors (inside-out signaling) with the crucial involvement of the Rap1-RIAM-Talin-1 pathway. Here, we analyze the implication of RIAM and its binding partner VASP in the signaling events occurring downstream of β₂ integrins (outside-in) during complement-mediated phagocytosis. To this end, we used HL-60 promyelocytic cell lines deficient in RIAM or VASP or overexpressing EGFP-tagged VASP to determine VASP dynamics at phagocytic cups. Our results indicate that RIAM-deficient HL-60 cells presented impaired particle internalization and altered integrin downstream signaling during complement-dependent phagocytosis. Similarly, VASP deficiency completely blocked phagocytosis, while VASP overexpression increased the random movement of phagocytic particles at the cell surface, with reduced internalization. Moreover, the recruitment of VASP to particle contact sites, amount of pSer157-VASP and formation of actin-rich phagocytic cups were dependent on RIAM expression. Our results suggested that RIAM worked as a relay for integrin complement receptors in outside-in signaling, coordinating integrin activation and cytoskeletal rearrangements via its interaction with VASP.

Understanding the Synergy of NKp46 and Co-Activating Signals in Various NK Cell Subpopulations: Paving the Way for More Successful NK-Cell-Based Immunotherapy

The NK cell population is characterized by distinct NK cell subsets that respond differently to the various activating stimuli. For this reason, the determination of the optimal cytotoxic activation of the different NK cell subsets can be a crucial aspect to be exploited to counter cancer cells in oncologic patients. To evaluate how the triggering of different combination of activating receptors can affect the cytotoxic responses of different NK cell subsets, we developed a microbead-based degranulation assay. By using this new assay, we were able to detect CD107a⁺ degranulating NK cells even within the less cytotoxic subsets (i.e., resting CD56^bright and unlicensed CD56^dim NK cells), thus demonstrating its high sensitivity. Interestingly, signals delivered by the co-engagement of NKp46 with 2B4, but not with CD2 or DNAM-1, strongly cooperate to enhance degranulation on both licensed and unlicensed CD56^dim NK cells. Of note, 2B4 is known to bind CD48 hematopoietic antigen, therefore this observation may provide the rationale why CD56^dim subset expansion correlates with successful hematopoietic stem cell transplantation mediated by alloreactive NK cells against host T, DC and leukemic cells, while sparing host non-hematopoietic tissues and graft versus host disease. The assay further confirms that activation of LFA-1 on NK cells leads to their granule polarization, even if, in some cases, this also takes to an inhibition of NK cell degranulation, suggesting that LFA-1 engagement by ICAMs on target cells may differently affect NK cell response. Finally, we observed that NK cells undergo a time-dependent spontaneous (cytokine-independent) activation after blood withdrawal, an aspect that may strongly bias the evaluation of the resting NK cell response. Altogether our data may pave the way to develop new NK cell activation and expansion strategies that target the highly cytotoxic CD56^dim NK cells and can be feasible and useful for cancer and viral infection treatment.

Understanding the Synergy of NKp46 and Co-Activating Signals in Various NK Cell Subpopulations: Paving the Way for More Successful NK-Cell-Based Immunotherapy

The NK cell population is characterized by distinct NK cell subsets that respond differently to the various activating stimuli. For this reason, the determination of the optimal cytotoxic activation of the different NK cell subsets can be a crucial aspect to be exploited to counter cancer cells in oncologic patients. To evaluate how the triggering of different combination of activating receptors can affect the cytotoxic responses of different NK cell subsets, we developed a microbead-based degranulation assay. By using this new assay, we were able to detect CD107a⁺ degranulating NK cells even within the less cytotoxic subsets (i.e., resting CD56^bright and unlicensed CD56^dim NK cells), thus demonstrating its high sensitivity. Interestingly, signals delivered by the co-engagement of NKp46 with 2B4, but not with CD2 or DNAM-1, strongly cooperate to enhance degranulation on both licensed and unlicensed CD56^dim NK cells. Of note, 2B4 is known to bind CD48 hematopoietic antigen, therefore this observation may provide the rationale why CD56^dim subset expansion correlates with successful hematopoietic stem cell transplantation mediated by alloreactive NK cells against host T, DC and leukemic cells, while sparing host non-hematopoietic tissues and graft versus host disease. The assay further confirms that activation of LFA-1 on NK cells leads to their granule polarization, even if, in some cases, this also takes to an inhibition of NK cell degranulation, suggesting that LFA-1 engagement by ICAMs on target cells may differently affect NK cell response. Finally, we observed that NK cells undergo a time-dependent spontaneous (cytokine-independent) activation after blood withdrawal, an aspect that may strongly bias the evaluation of the resting NK cell response. Altogether our data may pave the way to develop new NK cell activation and expansion strategies that target the highly cytotoxic CD56^dim NK cells and can be feasible and useful for cancer and viral infection treatment.

A research-driven approach to the identification of novel natural killer cell deficiencies affecting cytotoxic function

Natural killer cell deficiencies (NKDs) are an emerging phenotypic subtype of primary immune deficiency. NK cells provide a defense against virally infected cells using a variety of cytotoxic mechanisms, and patients who have defective NK cell development or function can present with atypical, recurrent, or severe herpesviral infections. The current pipeline for investigating NKDs involves the acquisition and clinical assessment of patients with a suspected NKD followed by subsequent in silico, in vitro, and in vivo laboratory research. Evaluation involves initially quantifying NK cells and measuring NK cell cytotoxicity and expression of certain NK cell receptors involved in NK cell development and function. Subsequent studies using genomic methods to identify the potential causative variant are conducted along with variant impact testing to make genotype-phenotype connections. Identification of novel genes contributing to the NKD phenotype can also be facilitated by applying the expanding knowledge of NK cell biology. In this review, we discuss how NKDs that affect NK cell cytotoxicity can be approached in the clinic and laboratory for the discovery of novel gene variants.