NK cell recognition

BTK inhibitors enhance NKG2D ligand expression by regulating IL-10/STAT3 pathway in activated non-GCB diffuse large B-cell lymphoma cells

The aim of this study is to explore the role of the IL-10/STAT3 pathway in the upregulation of natural killer group 2, member D (NKG2D) ligands (MICA and ULBP2) induced by Bruton's tyrosine kinase (BTK) inhibitors in non-germinal center B-cell-like diffuse large B-cell lymphoma cells. The expression levels of NKG2D ligands and the IL-10/STAT3 pathway in SUDHL4, U2932, and OCI-LY3 cells were analyzed using western blotting. After stimulation of the B-cell receptor signaling pathway with IgM antibodies, the expression levels of NKG2D ligands, as well as IL-10 and phosphorylated STAT3 (p-STAT3) were significantly reduced. In contrast, treatment with ibrutinib produced effects opposite to those induced by IgM antibodies. Additionally, treatment of U2932 and OCI-LY3 cells with the STAT3 inhibitor (STAT3-IN-1) led to an increase in NKG2D ligand expression and a decrease in IL-10 levels. When IL-10 neutralizing antibodies were introduced, p-STAT3 levels decreased, and NKG2D ligand expression increased. Similar outcomes were observed when the BTK inhibitors ACP-196 and BGB-3111 were administered. Our findings suggest that the IL-10/STAT3 pathway plays a key role in the upregulation of NKG2D ligands induced by BTK inhibitors in U2932 and OCI-LY3 cells.

Pathophysiology of bone remodelling cycle: Role of immune system and lipids

Osteoporosis is the most common skeletal disease worldwide, characterized by low bone mineral density, resulting in weaker bones, and an increased risk of fragility fractures. The maintenance of bone mass relies on the precise balance between bone synthesis and resorption. The close relationship between the immune and skeletal systems, called "osteoimmunology", was coined to identify these overlapping "scientific worlds", and its function resides in the evaluation of the mutual effects of the skeletal and immune systems at the molecular and cellular levels, in both physiological and pathological states. Lipids play an essential role in skeletal metabolism and bone health. Indeed, bone marrow and its skeletal components demand a dramatic amount of daily energy to control hematopoietic turnover, acquire and maintain bone mass, and actively being involved in whole-body metabolism. Statins, the main therapeutic agents in lowering plasma cholesterol levels, are able to promote osteoblastogenesis and inhibit osteoclastogenesis. This review is meant to provide an updated overview of the pathophysiology of bone remodelling cycle, focusing on the interplay between bone, immune system and lipids. Novel therapeutic strategies for the management of osteoporosis are also discussed.

Distinct Omicron longitudinal memory T cell profile and T cell receptor repertoire associated with COVID-19 hospitalisation

SARS-CoV-2 has claimed more than 7 million lives worldwide and has been associated with prolonged inflammation, immune dysregulation and persistence of symptoms following severe infection. Understanding the T cell mediated immune response and factors impacting development and continuity of SARS-CoV-2 specific memory T cells is pivotal for developing better therapeutic and monitoring strategies for those most at risk from COVID-19. Here we present a comprehensive analysis of memory T cells in a convalescent cohort (n=20), three months post Omicron infection. Utilising flow cytometry to investigate CD4+CD45RO+ and CD8+CD45RO+ memory T cell IL-2 expression following Omicron (B.1.1.529/BA.1) peptide pool stimulation, alongside T cell receptor repertoire profiling and RNA-Seq analysis, we have identified several immunological features associated with hospitalised status. We observed that while there was no significant difference in median CD4+CD45RO+ IL-2+ and CD8+ CD45RO+ IL-2+ memory T cell count between subgroups, the hospitalised subgroup expressed significantly more IL-2 per cell following Omicron peptide pool exposure in the CD8+CD45RO+ population (p <0.03) and trended towards significance in CD4+CD45RO+ cells (p <0.06). T cell receptor repertoire analysis found that the non-hospitalised subgroup had a much higher number of circulating clonotypes, targeting a wider range of predominantly MHC-I epitopes across the SARS-CoV-2 genome. Several immunodominant epitopes, conserved between both subgroups, were observed, however hospitalised individuals were less likely to express putative HLA alleles responsible for pMHC presentation which may impact TCR affinity. We observed a bias towards shorter CDR3 segments in TCRβ repertoire analysis within the hospitalised subgroup, alongside lower rates of repertoire overlap in CDR3 sequences compared to the non-hospitalised subgroup. We found a significant proportion of TCRs targeted epitopes along the SARS-CoV-2 genome including non-structural proteins, responsible for viral replication and immune evasion. These findings highlight how the continuity of T cell based protective immunity is impacted by both the viral replication cycle of SARS-CoV-2 upon intracellular and innate immune responses, and HLA-type upon TCR affinity and clonotype formation. Our novel Epitope Target Analysis Pipeline (Epi-TAP) could prove beneficial in development of new therapeutic strategies through rapid identification of shared immunodominant epitopes across non-hospitalised and hospitalised subgroups.

Sesamin induces cell cycle arrest and upregulation of NKG2D ligands in MG‑63 cells and increases susceptibility to NK cell cytotoxicity

Osteosarcoma is a common solid malignancy in children and adolescents. Despite a success of standard therapeutic approaches, an effective therapeutic strategy is in a great need for improved outcomes. The aim of the present study was to investigate the anticancer effect of sesamin and its influence on NKG2D ligand expression in human osteosarcoma MG-63 cells and to compare the differences in NK cell elimination efficiency before and after treatment. Cell viability of MG-63 cells treated with serial concentrations of sesamin (0-100 µM) was measured using MTT. Induction of cell cycle arrest was determined with flow cytometry. Flow cytometry and reverse transcription-quantitative PCR were employed to detect the changes of protein and mRNA level of NKG2D ligands before and after treatment with sesamin. NK cell elimination assay was performed to determine the changes in NK cell-mediated cytotoxicity against MG-63 cells treated with sesamin. Sesamin induced G2/M cell cycle arrest in MG-63 cells with increased p21 expression. Expression of MICA, MICB and ULBP1 at the protein and mRNA level were significantly increased (P<0.05). MG-63 cells treated with sesamin were more susceptible to NK cell-mediated elimination (P<0.05). Enhanced NK cell-mediated cytotoxicity was correlated with expression of NKG2D ligands (P<0.05). In conclusion, sesamin can induce cell cycle arrest and upregulate the expression of NKG2D ligands in MG-63 cells, thereby enhancing NK cell-mediated cytotoxicity against osteosarcoma cells.

The clinical landscape of CAR NK cells

Chimeric antigen receptor (CAR) NK cell therapy has emerged as a promising alternative to CAR T cell therapy, offering significant advantages in terms of safety and versatility. Here we explore the current clinical landscape of CAR NK cells, and their application in hematologic malignancies and solid cancers, as well as their potential for treating autoimmune disorders. Our analysis draws from data collected from 120 clinical trials focused on CAR NK cells, and presents insights into the demographics and characteristics of these studies. We further outline the specific targets and diseases under investigation, along with the major cell sources, genetic modifications, combination strategies, preconditioning- and dosing regimens, and manufacturing strategies being utilized. Initial results from 16 of these clinical trials demonstrate promising efficacy of CAR NK cells, particularly in B cell malignancies, where response rates are comparable to those seen with CAR T cells but with lower rates of severe adverse effects, such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and graft-versus-host disease (GvHD). However, challenges remain in solid tumor applications, where only modest efficacy has been observed to date. Our analysis reveals that research is increasingly focused on enhancing CAR NK cell persistence, broadening their therapeutic targets, and refining manufacturing processes to improve accessibility and scalability. With recent advancements in NK cell engineering and their increased clinical applications, CAR NK cells are predicted to become an integral component of next-generation immunotherapies, not only for cancer but potentially for immune-mediated diseases as well.

Decreased surface receptors, function, and suboptimal osteoclasts-induced cell expansion in natural killer (NK) cells of elderly subjects

Natural killer (NK) cells are known for their cytotoxic and cytokine secretion capabilities. The balance of activating and inhibitory receptors on their surface regulates NK cell function and survival. However, it is not fully understood how aging may modulate the levels of NK cell surface receptors ultimately affecting their interaction with other immune cells, especially with those known to activate and expand NK cells. Here, we report decreased levels of NK cells' surface receptors, cytotoxic function, and cytokine secretion in aged donors (75-85 years) as compared to younger donors (21-25 years). We used our previously established methodology to expand and supercharge NK cells from young and older individuals using osteoclasts (OCs) and probiotic bacteria. Significantly lower levels of NK cell expansion and functional activation were seen in NK cells from 75-85-year-old donors when compared to younger donors' NK cells. Surface receptors of OCs were also found to be decreased in 75-85-year-old donors compared to younger donors. In addition, OCs from 75-85-year-old donors induced lower levels of cell expansion and functional activation of NK cells when compared to OCs from younger donors. These findings illustrate defects in both peripheral blood-derived primary NK cells and OCs in older individuals; however, suppression appears to be more in NK cells when compared to OCs.

Molecular biology of the deadliest cancer - glioblastoma: what do we know?

Glioblastomas are the most prevalent primary brain tumors and are associated with a dramatically poor prognosis. Despite an intensive treatment approach, including maximal surgical tumor removal followed by radio- and chemotherapy, the median survival for glioblastoma patients has remained around 18 months for decades. Glioblastoma is distinguished by its highly complex mechanisms of immune evasion and pronounced heterogeneity. This variability is apparent both within the tumor itself, which can exhibit multiple phenotypes simultaneously, and in its surrounding microenvironment. Another key feature of glioblastoma is its "cold" microenvironment, characterized by robust immunosuppression. Recent advances in single-cell RNA sequencing have uncovered new promising insights, revealing previously unrecognized aspects of this tumor. In this review, we consolidate current knowledge on glioblastoma cells and its microenvironment, with an emphasis on their biological properties and unique patterns of molecular communication through signaling pathways. The evidence underscores the critical need for personalized poly-immunotherapy and other approaches to overcome the plasticity of glioblastoma stem cells. Analyzing the tumor microenvironment of individual patients using single-cell transcriptomics and implementing a customized immunotherapeutic strategy could potentially improve survival outcomes for those facing this formidable disease.

PRSS53 is a potential novel biomarker related to prognosis and immunity in clear cell renal cell carcinoma

OBJECTIVE

To analyze the expression levels, clinical significance, Immune infiltration and prognostic value of PRSS53 (Protease Serine 53) in clear cell renal cell carcinoma (ccRCC) using bioinformatics methods.

METHODS

Data on PRSS53 in ccRCC were extracted from databases and platforms, including The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression Project (GTEx), The Gene Expression Omnibus (GEO), Xiantao Academic Tool, Human Protein Atlas (HPA) and so on. We analyzed the relationship between PRSS53 expression and the clinical and pathological characteristics, diagnosis, immune infiltration and prognosis in ccRCC patients. Additionally, immunohistochemical analysis was performed on 9 pairs of ccRCC patient samples.

RESULTS

PRSS53 was significantly upregulated in ccRCC and was closely associated with the TNM stage and histological grade of ccRCC. Receiver operating characteristic (ROC) curve analysis demonstrated the excellent diagnostic performance of PRSS53 in ccRCC (AUC = 0.928). Patients with high PRSS53 expression exhibited lower overall survival (OS) and disease-specific survival (DSS). Gene set enrichment analysis (GSEA) revealed that PRSS53 is involved in cellular functions such as anchored component of membrane, basement membrane and RNA-binding involved in post-transcriptional gene silencing. Single-sample GSEA (ssGSEA) indicated a positive correlation between PRSS53 expression and T helper cells infiltration levels, and a negative correlation with T gamma delta (Tgd) cell infiltration. PRSS53 was predominantly expressed in renal proximal tubules. The immunohistochemical results and HPA database showed that PRSS53 protein expression was significantly lower in clinical ccRCC tissues  compared to normal tissues.

CONCLUSION

PRSS53 is a new prognostic biomarker and potential therapeutic target for ccRCC.

Immune evasion runs in the family: two surface protein families of Plasmodium falciparum-infected erythrocytes

Two protein families are found on the surfaces of erythrocytes infected with Plasmodium falciparum, a causative agent of deadly malaria. PfEMP1 are tethers binding endothelial receptors and holding infected erythrocytes to tissue and blood vessel surfaces, away from splenic clearance. RIFINs interact with immune receptors on natural killer cells, suppressing infected erythrocyte destruction. Both have expanded into families of diverse members to allow antigenic variation but retain surfaces of conserved chemistry and shape to bind human receptors. Recently discovered broadly inhibitory antibodies target one such surface on many EPCR-binding PfEMP1. Remarkable antibodies take this one step further, directly incorporating ectodomains of immune receptors into their loops, allowing RIFIN recognition. Finally, some RIFINs are targets of activating killer immune receptors, helping natural killer cells destroy infected erythrocytes. Studies of these two families therefore reveal a snapshot of the battle between this ancient parasite and the immune system of its human host.

SYK negatively regulates ITAM-mediated human NK cell signaling and CD19-CAR NK cell efficacy

Natural killer (NK) cells express activating receptors that signal through ITAM (immunoreceptor tyrosine-based activation motif)-bearing adapter proteins. The phosphorylation of each ITAM creates binding sites for SYK and ZAP70 protein tyrosine kinases to propagate downstream signaling including the induction of Ca2+ influx. While all immature and mature human NK cells coexpress SYK and ZAP70, clonally driven memory or adaptive NK cells can methylate SYK genes, and signaling is mediated exclusively using ZAP70. Here, we examined the role of SYK and ZAP70 in a clonal human NK cell line KHYG1 by CRISPR-based deletion using a combination of experiments and mechanistic computational modeling. Elimination of SYK resulted in more robust Ca2+ influx after crosslinking of the CD16 and NKp30 receptors and enhanced phosphorylation of downstream proteins, whereas ZAP70 deletion diminished these responses. By contrast, ZAP70 depletion increased proliferation of the NK cells. As immature T cells express both SYK and ZAP70 and mature T cells often express only ZAP70, we transduced the human Jurkat cell line with SYK and found that expression of SYK increased proliferation but diminished T cell receptor-induced Ca2+ flux and activation. We performed transcriptional analysis of the matched sets of variant Jurkat and KHYG1 cells and observed profound alterations caused by SYK expression. As depletion of SYK in NK cells increased their activation, primary human NK cells were transduced with a CD19-targeting chimeric antigen receptor and were CRISPR edited to ablate SYK or ZAP70. Deletion of SYK resulted in more robust cytotoxic activity and cytokine production, providing a new therapeutic strategy of NK cell engineering for cancer immunotherapy.

A chimeric antigen receptor tailored to integrate complementary activation signals potentiates the antitumor activity of NK cells

BACKGROUND

Chimeric antigen receptors (CARs) are synthetic receptors that reprogram the target specificity and functions of CAR-expressing effector cells. The design of CAR constructs typically includes an extracellular antigen-binding moiety, hinge (H), transmembrane (TM), and intracellular signaling domains. Conventional CAR constructs are primarily designed for T cells but have been directly adopted for other effector cells, including natural killer (NK) cells, without tailored optimization. Given the benefits of CAR-NK cells over CAR-T cells in terms of safety, off-the-shelf utility, and antigen escape, there is an increasing emphasis on tailoring them to NK cell activation mechanisms.

METHODS

We first have taken a stepwise approach to modifying CAR components such as the combination and order of the H, TM, and signaling domains to achieve such tailoring in NK cells. Functionality of NK-tailored CARs were evaluated in vitro and in vivo in a model of CD19-expressing lymphoma, along with their expression and signaling properties in NK cells.

RESULTS

We found that NK-CAR driven by the synergistic combination of NK receptors NKG2D and 2B4 rather than DNAM-1 and 2B4 induces potent activation in NK cells. Further, more effective CAR-mediated cytotoxicity was observed following the sequential combination of DAP10, but not NKG2D TM, with 2B4 signaling domain despite the capacity of NKG2D TM to recruit endogenous DAP10 for signaling. Accordingly, an NK-CAR incorporating DAP10, 2B4, and CD3ζ signaling domains coupled to CD8α H and CD28 TM domains was identified as the most promising candidate to improve CAR-mediated cytotoxicity. This NK-tailored CAR provided more potent antitumor activity than a conventional T-CAR when delivered to NK cells both in vitro and in vivo.

CONCLUSIONS

Hence, NK receptor-based domains hold great promise for the future of NK-CAR design with potentially significant therapeutic benefits.

Targeting Immune Checkpoint Inhibitors for Non-Small-Cell Lung Cancer: Beyond PD-1/PD-L1 Monoclonal Antibodies

Non-small-cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide. Immunotherapy targeting the PD-1/PD-L1 axis has revolutionized treatment, providing durable responses in a subset of patients. However, with fewer than 50% of patients achieving significant benefits, there is a critical need to expand therapeutic strategies. This review explores emerging targets in immune checkpoint inhibition beyond PD-1/PD-L1, including CTLA-4, TIGIT, LAG-3, TIM-3, NKG2A, and CD39/CD73. We highlight the biological basis of CD8 T cell exhaustion in shaping the antitumor immune response. Novel therapeutic approaches targeting additional inhibitory receptors (IR) are discussed, with a focus on their distinct mechanisms of action and combinatory potential with existing therapies. Despite significant advancements, challenges remain in overcoming resistance mechanisms and optimizing patient selection. This review underscores the importance of dual checkpoint blockade and innovative bispecific antibody engineering to maximize therapeutic outcomes for NSCLC patients.

Current Scenario and Future Perspectives of Porcine Corneal Xenotransplantation

ABSTRACT

Corneal diseases represent a significant cause of blindness worldwide, with corneal transplantation being an effective treatment to prevent vision loss. Despite substantial advances in transplantation techniques, the demand for donor corneas exceeds the available supply, particularly in developing countries. Cornea xenotransplantation has emerged as a promising strategy to address the worldwide scarcity, notably using porcine corneas. In addition to the inherent immune privilege of the cornea, the low cost of porcine breeding and the anatomical and physiological similarities between humans and pigs have made porcine corneas a viable alternative. Nonetheless, ethical concerns, specifically the risk of xenozoonotic transmission and the necessity for stringent biosafety measures, remain significant obstacles. Moreover, the success of xenotransplantation is compromised by innate and adaptive immune responses, which requires meticulous consideration and further studies. Despite these challenges, recent breakthroughs have further contributed to reducing immunogenicity while preserving the corneal architecture. Advances in genetic engineering, such as the use of CRISPR-Cas9 to eliminate critical porcine antigens, have shown promise for mitigating immune reactions. Additionally, new immunosuppressive protocols, such as have techniques like decellularization and the use of porcine-derived acellular matrices, have greatly increased graft survival in preclinical models. Future research must focus on refining immunomodulatory strategies and improving graft preparation techniques to ensure the long-term survival and safety of porcine corneal xenotransplantation in clinical trials in humans.

NCAM1-SHIP2 axis upon recognizing microbes inhibits the expressions of inflammatory factors through P38-H3K4me and P38-NF-κB pathways in oyster

Neural cell adhesion molecule 1 (NCAM1/CD56) as a well-known surface marker for natural killer (NK) cells plays important roles in cell migration, adhesion, and inflammation. In the present study, NCAM1 homolog containingthree immunoglobulin domains, one fibronectin type 3 domain, a transmembrane region and a cytoplasmic tail with two intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIMs) was identified from the Pacific oyster, Crassostrea gigas (defined as CgNCAM1). The mRNA transcripts of CgNCAM1 were highly expressed in haemocytes. The mRNA expressions of CgNCAM1 in haemocytes increased significantly after Vibrio splendidus stimulation. The positive green signals of CgNCAM1 and SH2-containing inositol 5-phosphatase (CgSHIP2) could translocate onto the haemocyte membrane after V. splendidus stimulation. The recombinant extracellular domains of CgNCAM1 exhibited binding activity towards various pathogen-associated molecular patterns (PAMPs) and microbes. Upon binding to its ligands, CgNCAM1 recruited CgSHIP2 to transduce inhibitor signals to reduce the phosphorylation of CgP38. The inhibition of CgP38 reduced the methylation of histone H3K4 and nuclear translocation of NF-κB, which eventually inhibited the mRNA expressions of inflammatory factors (CgIL17-2/3/6 and CgTNF-2) to suppress inflammation. These results suggested that CgNCAM1 could function as an immune checkpoint to sense different PAMPs and microbes and reduce the inflammation through inhibiting P38-epigenetic and P38-NF-κB pathways in oysters.

NK cell-based immunotherapy for hepatocellular carcinoma: Challenges and opportunities

Hepatocellular carcinoma (HCC) remains one of the most challenging malignancies globally, characterized by significant heterogeneity, late-stage diagnosis, and resistance to treatment. In recent years, the advent of immune-checkpoint blockades (ICBs) and targeted immune cell therapies has marked a substantial advancement in HCC treatment. However, the clinical efficacy of these existing therapies is still limited, highlighting the urgent need for new breakthroughs. Natural killer (NK) cells, a subset of the innate lymphoid cell family, have shown unique advantages in the anti-tumour response. With increasing evidence suggesting the crucial role of dysfunctional NK cells in the pathogenesis and progression of HCC, considerable efforts have been directed toward exploring NK cells as a potential therapeutic target for HCC. In this review, we will provide an overview of the role of NK cells in normal liver immunity and in HCC, followed by a detailed discussion of various NK cell-based immunotherapies and their potential applications in HCC treatment.

Targeting glutamine metabolism crosstalk with tumor immune response

Glutamine, akin to glucose, is a fundamental nutrient for human physiology. Tumor progression is often accompanied by elevated glutamine consumption, resulting in a disrupted nutritional balance and metabolic reprogramming within the tumor microenvironment. Furthermore, immune cells, which depend on glutamine for metabolic support, may experience functional impairments and dysregulation. Although the role of glutamine in tumors has been extensively studied, the specific impact of glutamine competition on immune responses, as well as the precise cellular alterations within immune cells, remains incompletely understood. In this review, we summarize the consequences of glutamine deprivation induced by tumor-driven glutamine uptake on immune cells, assessing the underlying mechanisms from the perspective of various components of the immune microenvironment. Additionally, we discuss the potential synergistic effects of glutamine supplementation and immunotherapy, offering insights into future research directions. This review provides compelling evidence for the integration of glutamine metabolism and immunotherapy as a promising strategy in cancer therapy.

Immune responses to avian influenza viruses in chickens

Chickens are a key species in both the manifestation of avian influenza and the potential for zoonotic transmission. Avian influenza virus (AIV) infection in chickens can range from asymptomatic or mild disease with low pathogenic AIVs (LPAIVs) to systemic fatal disease with high pathogenic AIVs (HPAIVs). During AIV infection in chickens, Toll-like receptor 7 and melanoma differentiation-associated gene 5 are upregulated to detect the single-stranded ribonucleic acid genomes of AIV, triggering a signaling cascade that produces interferons (IFNs) and pro-inflammatory cytokines. These inflammatory mediators induce the expression of antiviral proteins and recruit immune system cells, such as macrophages and dendritic cells, to the infection site. AIV evades these antiviral responses primarily through its non-structural protein 1, which suppresses type I IFNs, influencing viral pathogenicity. The uncontrolled release of pro-inflammatory cytokines may contribute to the pathogenicity and high mortality associated with HPAIV infections. AIV modulates apoptosis in chicken cells to enhance its replication, with variations in apoptosis pathways influenced by viral strain and host cell type. The presentation of AIV antigens to T and B cells leads to the production of neutralizing antibodies and the targeted destruction of infected cells by CD8+ T cells, respectively, which enhances protection and establishes immunological memory. This review explores the diverse innate and adaptive immune responses in chickens to different AIVs, focusing on the dynamics of these responses relative to protection, susceptibility, and potential immunopathology. By understanding these immune mechanisms, informed strategies for controlling AIV infection and improving chicken health can be developed.

Nanomedicine in Immunotherapy for Non-Small Cell Lung Cancer: Applications and Perspectives

Non-small cell lung cancer (NSCLC) has a strikingly high incidence rate globally. Although immunotherapy brings a great breakthrough in its clinical treatment of NSCLC, significant challenges still need to be overcome. The development of novel multi-functional nanomedicines in the realm of tumor immunotherapy offers promising opportunities for NSCLC patients, as nanomedicines exhibit significant advantages, including specific targeting of tumor cells, improved drug bioavailability, reduced systemic toxicity, and overcoming of immune resistance. In this review, the core features and current clinical status of strategies for NSCLC immunotherapy including immune checkpoint blockade, antibody-drug conjugates, cell engagers, adoptive cells, and cancer vaccines, are surveyed. Particular emphasis is placed on the recent development of nanomedicines that boost these strategies. Nanomedicine can provide novel perspectives for NSCLC immunotherapy.

Reversing NK cell exhaustion: a novel strategy combining immune checkpoint blockade with drug sensitivity enhancement in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common lethal cancers worldwide. Natural killer cells (NK cells) play a key role in liver immunosurveillance, but in the tumor microenvironment, NK cells are readily depleted, as evidenced by down-regulation of activating receptors, reduced cytokine secretion, and attenuated killing function. The up-regulation of inhibitory receptors, such as PD-1, TIM-3, and LAG-3, further exacerbates the depletion of NK cells. Combined blockade strategies targeting these immunosuppressive mechanisms, such as the combination of PD-1 inhibitors with other inhibitory pathways (eg. TIM-3 and LAG-3), have shown potential to reverse NK cell exhaustion in preclinical studies. This article explores the promise of these innovative strategies in HCC immunotherapy, providing new therapeutic directions for optimizing NK cell function and improving drug sensitivity.

Natural Killer Cell-Secreted IFN-γ and TNF-α Mediated Differentiation in Lung Stem-like Tumors, Leading to the Susceptibility of the Tumors to Chemotherapeutic Drugs

We demonstrate that natural killer (NK) cells induce a higher cytotoxicity against lung cancer stem-like cells (hA549) compared to differentiated lung cancer cell lines (H292). The supernatants from split-anergized NK cells (IL-2 and anti-CD16 mAb-treated NK cells) induced differentiation in hA549. Differentiated lung cancer cell line (H292) and NK cells differentiated hA549 expressed reduced NK cell-mediated cytotoxicity but expressed higher sensitivity to chemotherapeutic drugs. This finding validated our previous reports demonstrating that the levels of tumor killing by NK cells and by chemotherapeutic drugs correlate directly and indirectly, respectively, with the stage and levels of tumor differentiation. We also demonstrate the role of IFN-γ and TNF-α in inducing tumor differentiation. NK cells' supernatants or IFN-γ and TNF-α-induced tumor differentiation was blocked when we used antibodies against IFN-γ and TNF-α. Therefore, IFN-γ and TNF-α released from NK cells play a significant role in differentiating tumors, resulting in increased susceptibility of tumors to chemotherapeutic drugs. We also observed the different effects of MHC-class I antibodies in CSCs vs. differentiated tumors. Treatment with anti-MHC-class I decreased NK cell-mediated cytotoxicity in hA549 tumors, whereas it increased NK cell-mediated cytotoxicity when differentiated tumors were treated with antibodies against MHC-class I.

Immune Tolerance Regulation Is Critical to Immune Homeostasis

The body's immune response plays a critical role in defending against external or foreign antigens while also preserving tolerance to self-antigens. This equilibrium, referred to as immune homeostasis, is paramount for overall health. The regulatory mechanisms governing the maintenance of this delicate immune balance are notably complex. It is currently accepted that immune tolerance is a dynamic outcome regulated by multiple factors, including central and peripheral mechanisms. Its induction or elimination plays a significant role in autoimmune diseases, organ transplantation, and cancer therapy, markedly impacting various major diseases in modern clinical practice. Overall, our current understanding of immune tolerance is still very limited. In this review article, we summarized the main mechanisms that have been known to mediate immune tolerance so far, including endogenous immune tolerance, adaptive immune tolerance, other immune tolerance mechanisms, and the homeostasis of immune tolerance, identified the key factors that regulate immune tolerance, and provided new clues for immune system recovery in many autoimmune diseases, organ transplantation, and tumor therapy.

Recognition of Self and Viral Ligands by NK Cell Receptors

Natural killer (NK) cells are essential elements of the innate immune response against tumors and viral infections. NK cell activation is governed by NK cell receptors that recognize both cellular (self) and viral (non-self) ligands, including MHC, MHC-related, and non-MHC molecules. These diverse receptors belong to two distinct structural families, the C-type lectin superfamily and the immunoglobulin superfamily. NK receptors include Ly49s, KIRs, LILRs, and NKG2A/CD94, which bind MHC class I (MHC-I) molecules, and NKG2D, which binds MHC-I paralogs such MICA and ULBP. Other NK receptors recognize tumor-associated antigens (NKp30, NKp44, NKp46), cell-cell adhesion proteins (KLRG1, CD96), or genetically coupled C-type lectin-like ligands (NKp65, NKR-P1). Additionally, cytomegaloviruses have evolved various immunoevasins, such as m157, m12, and UL18, which bind NK receptors and act as decoys to enable virus-infected cells to escape NK cell-mediated lysis. We review the remarkable progress made in the past 25 years in determining structures of representatives of most known NK receptors bound to MHC, MHC-like, and non-MHC ligands. Together, these structures reveal the multiplicity of solutions NK receptors have developed to recognize these molecules, and thereby mediate crucial interactions for regulating NK cytolytic activity by self and viral ligands.

Homeostatic self-MHC-I recognition regulates anti-metastatic function of mature lung natural killer cells

Natural killer (NK) cells are important innate immune effector cells for controlling tumor growth and metastasis. Differentiated mature NK cells preferentially reside in the peripheral tissues and express higher levels of self-major histocompatibility complex class I (MHC-I)-recognizing inhibitory receptors. MHC-I recognition by NK cells are known to be important for their development and maturation processes, however, the role of homeostatic MHC-I recognition in maintaining effector functions of mature NK cells in the peripheral tissues needs to be elucidated. In this study, we utilized a pan anti-MHC-I blocking monoclonal antibody (anti-MHC-I) to examine the role of homeostatic MHC-I recognition in the response of pulmonary mature NK cells in an experimental lung metastasis model of B16F10 melanoma. Anti-MHC-I treatment showed significant inhibition of the lung metastasis of B16F10 melanoma in NK cell- and IFN-γ-dependent mechanisms. The blockade of homeostatic MHC-I recognition increased mature lung NK cell responsiveness, such as direct cytotoxicity and IFN-γ production, rather than the number of lung NK cells. Mechanistically, the gene expression of activating receptors including DNAX accessory molecule-1 (DNAM-1) was upregulated in NK cells treated with anti-MHC-I, and further the enhanced NK cell cytotoxicity against B16F10 cells was DNAM-1-dependent. Collectively, homeostatic self-MHC-I recognition regulates anti-metastatic function of mature lung NK cells by restraining the expression of activating receptors.

Rhesus Macaque Killer Cell Ig-like Receptor Domain 0 Glycans Impact Surface Expression and Ligand Specificity

Defining the MHC class I ligands of rhesus macaque killer cell Ig-like receptors (KIRs) is fundamental to NK cell biology in this species as a model for infectious diseases and comparative immunogenetics. Several rhesus macaque KIRs belong to a phylogenetically distinct group with a three-amino acid deletion in domain 0 (D0). This deletion results in polymorphic differences in potential N-linked glycosylation (PNG) sites adjacent to a predicted KIR-MHC class I contact site. Whereas most KIRs have two tandem PNG sites in D0 (N36FTN39FT), the KIRs containing the deletion only have a single site in this region (N36FT). To discern the contribution of glycosylation to KIR expression and ligand recognition, we constructed PNG mutants for six lineage II KIR genes that eliminate or create sites for N-glycan addition at these locations. The impact of these mutations on total and surface expression was determined by immunoblotting and flow cytometry. Ligand engagement was assessed by coincubating reporter cell lines bearing chimeric KIR-CD3ζ receptors with target cells expressing individual MHC class I molecules and were corroborated by staining with KIR IgG-Fc fusion proteins. We found that N36FT is glycosylated in KIR with a single site, and at least one site is glycosylated in KIRs with two tandem sites. In general, for rhesus KIRs with a single D0 glycosylation site, that site contributes to surface expression. For KIRs with two tandem sites, the first site can contribute to ligand specificity. This study establishes that D0 glycosylation of rhesus macaque KIRs modulates surface expression and contributes to ligand specificity.

CD4 Co-Receptor Regulates Sex-Specific NK Cell Responses to Acute Toxoplasma gondii Infection

Immunity to Toxoplasma gondii ( T. gondii ) is sexually dimorphic in humans and mice, with females having higher morbidity and mortality during immune dysfunction and HIV-AIDS. The mechanisms underlying these sex differences are unclear. We investigated how a lack of CD4+ T cells (CD4 co-receptor KO) impacted T. gondii survival in mice. Female CD4 co-receptor KO mice succumbed to T. gondii much faster than males. To dissect why female CD4 co-receptor KO mice died faster, we tested their NK cell responses to acute T. gondii infection compared to males. Although in wild-type (WT) animals, both sexes had similar increases in total NK cells and IFNγ + NK cells, infected CD4 co-receptor KO female mice had 50% fewer IFNγ+ NK cells than infected WT female mice. Infected male CD4 co-receptor KO had a similar increase in IFNγ+ NK cells as WT male mice. Since CD4 co-receptor deficient mice still have functional helper T cells that are CD4-, we next tested survival and NK cell responses in female and male MHCII deficient (MHCIIKO) animals, which completely lack helper CD4+T cells. Surprisingly, survival, NK cell numbers, and IFNγ+ NK cells were not significantly different between WT or MHCIIKO female and male mice. These results suggest CD4 co-receptor expression is required for survival via optimal NK cell responses during acute T. gondii infection only in female mice and not in male mice. Our findings reveal an unappreciated sexual dimorphic role of CD4 co-receptor expression in regulating NK cell responses to acute T. gondii infection.

Natural killer cells in neuroblastoma: immunological insights and therapeutic perspectives

Natural killer (NK) cells have multifaceted roles within the complex tumor milieu. They are pivotal components of innate immunity and shape the dynamic landscape of tumor-immune cell interactions, and thus can be leveraged for use in therapeutic interventions. NK-based immunotherapies have had remarkable success in hematological malignancies, but these therapies are met with many challenges in solid tumors, including neuroblastoma (NB), a childhood tumor arising from the sympathetic nervous system. With a focus on NB, this review outlines the mechanisms employed by NK cells to recognize and eliminate malignant cells, delving into the dynamic relationship between ligand-receptor interactions, cytokines, and other molecules that facilitate the cross talk between NK and NB cells. We discuss the immunomodulatory functions of NK cells and the mechanisms that contribute to loss of this immunosurveillance in NB, with a focus on how this dynamic has been utilized in recent immunotherapy advancements for NB.

Electroacupuncture suppresses NK cell infiltration and activation in the ischemic mouse brain through STAT3 inhibition

AIMS

Electroacupuncture (EA) at Shuigou (GV26) and Baihui (GV20) has shown therapeutic benefits for stroke patients. Given that natural killer (NK) cell infiltration into the brain significantly contributes to the exacerbation of cerebral ischemic injury, this study investigated the impact of EA at Shuigou (GV26) and Baihui (GV20) on post-ischemic brain infiltration and activation of NK cells.

METHODS

Neurological deficit score, rotarod test, adhesive removal test, and TTC staining were used to evaluate the beneficial effects of EA in middle cerebral artery occlusion (MCAO) mice. The inhibitory effect of EA on STAT3 activation was assessed using Western blot. Flow cytometry was used to explore the impact of EA on post-ischemic brain infiltration of NK cells, as well as the activating receptor NKG2D expression and interferon-γ (IFN-γ) production by these infiltrated NK cells.

RESULTS

EA significantly alleviated neurological functional deficits and reduced brain infarction in MCAO mice. Abundant NK cells infiltrated into the ischemic hemisphere, but this infiltration was significantly suppressed by EA. Furthermore, EA attenuated NKG2D levels and reduced production of IFN-γ by NK cells in the ischemic brain. Notably, EA's inhibitory effect on post-ischemic NK cell brain infiltration and activation was comparable to that of STAT3 inhibition. The combination of EA and STAT3 inhibition did not result in further enhancement of the inhibitory effect. Moreover, the protective effects of EA against MCAO injury were abolished when STAT3 was activated.

CONCLUSION

Our findings suggest that EA at Shuigou (GV26) and Baihui (GV20) inhibits the post-ischemic brain infiltration and activation of NK cells through STAT3 inhibition, significantly contributing to its therapeutic effects against brain ischemia.

Developing enhanced immunotherapy using NKG2A knockout human pluripotent stem cell-derived NK cells

Cancer immunotherapy is gaining increasing attention. However, immune checkpoints are exploited by cancer cells to evade anti-tumor immunotherapy. Here, we knocked out NKG2A, an immune checkpoint expressed on natural killer (NK) cells, in human pluripotent stem cells (hPSCs) and differentiated these hPSCs into NK (PSC-NK) cells. We show that NKG2A knockout (KO) enhances the anti-tumor and anti-viral capabilities of PSC-NK cells. NKG2A KO endows PSC-NK cells with higher cytotoxicity against HLA-E-expressing glioblastoma (GBM) cells, leukemia cells, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected cells in vitro. The NKG2A KO PSC-NK cells also exerted potent anti-tumor activity in vivo, leading to substantially suppressed tumor progression and prolonged survival of tumor-bearing mice in a xenograft GBM mouse model. These findings underscore the potential of PSC-NK cells with immune checkpoint KO as a promising cell-based immunotherapy. The unlimited supply and ease of genetic engineering of hPSCs makes genetically engineered PSC-NK an attractive option for easily accessible "off-the-shelf" cancer immunotherapy.

Metabolic reprogramming and therapeutic resistance in primary and metastatic breast cancer

Metabolic alterations, a hallmark of cancer, enable tumor cells to adapt to their environment by modulating glucose, lipid, and amino acid metabolism, which fuels rapid growth and contributes to treatment resistance. In primary breast cancer, metabolic shifts such as the Warburg effect and enhanced lipid synthesis are closely linked to chemotherapy failure. Similarly, metastatic lesions often display distinct metabolic profiles that not only sustain tumor growth but also confer resistance to targeted therapies and immunotherapies. The review emphasizes two major aspects: the mechanisms driving metabolic resistance in both primary and metastatic breast cancer, and how the unique metabolic environments in metastatic sites further complicate treatment. By targeting distinct metabolic vulnerabilities at both the primary and metastatic stages, new strategies could improve the efficacy of existing therapies and provide better outcomes for breast cancer patients.

Genotype-specific Expression of Uncle Fester Suggests a Role in Allorecognition Education in a Basal Chordate

Histocompatibility is the ability to discriminate between self and non-self tissues, and has been described in species throughout the metazoa. Despite its universal presence, histocompatibility genes utilized by different phyla are unique-those found in sponges, cnidarians, ascidians, and vertebrates are not orthologous. Thus, the origins of these sophisticated recognition systems, and any potential functional commonalities between them, are not understood. We are studying histocompatibility in the botryllid ascidians, members of the chordate subphylum, Tunicata, which provide a powerful model to understand both the origins and functional aspects of this process. Histocompatibility in the botryllids occurs at the tips of an extracorporeal vasculature that come into contact when two individuals grow into proximity. If compatible, the vessels will fuse, forming a parabiosis between the two individuals. If incompatible, the two vessels will reject-an inflammatory reaction that results in melanin scar formation at the point of contact, blocking anastomosis. Compatibility is determined by a single, highly polymorphic locus called the fuhc with the following rules: individuals that share one or both fuhc alleles will fuse, while those who share neither will reject. The fuhc locus encodes at least six proteins with known roles in allorecognition. One of these genes, called uncle fester, is necessary and sufficient to initiate the rejection response. Here, we report the existence of genotype-specific expression levels of uncle fester, differing by up to eight-fold at the mRNA-level, and that these expression levels are constant and maintained for the lifetime of an individual. We also found that these differences had functional consequences: the expression level of uncle fester correlated with the speed and severity of the rejection response. These findings support previous conclusions that uncle fester levels modulate the rejection response, and may be responsible for controlling the variation observed in the timing and intensity of the reaction. The maintenance of genotype specific expression of uncle fester is also evidence of an education process reminiscent of that which occurs in mammalian Natural Killer cells. In turn, this suggests that while histocompatibility receptors and ligands evolve via convergent evolution, they may utilize conserved intracellular machinery to interpret binding events at the cell surface.

Comprehensive snapshots of natural killer cells functions, signaling, molecular mechanisms and clinical utilization

Natural killer (NK) cells, initially identified for their rapid virus-infected and leukemia cell killing and tumor destruction, are pivotal in immunity. They exhibit multifaceted roles in cancer, viral infections, autoimmunity, pregnancy, wound healing, and more. Derived from a common lymphoid progenitor, they lack CD3, B-cell, or T-cell receptors but wield high cytotoxicity via perforin and granzymes. NK cells orchestrate immune responses, secreting inflammatory IFNγ or immunosuppressive TGFβ and IL-10. CD56dim and CD56bright NK cells execute cytotoxicity, while CD56bright cells also regulate immunity. However, beyond the CD56 dichotomy, detailed phenotypic diversity reveals many functional subsets that may not be optimal for cancer immunotherapy. In this review, we provide comprehensive and detailed snapshots of NK cells' functions and states of activation and inhibitions in cancer, autoimmunity, angiogenesis, wound healing, pregnancy and fertility, aging, and senescence mediated by complex signaling and ligand-receptor interactions, including the impact of the environment. As the use of engineered NK cells for cancer immunotherapy accelerates, often in the footsteps of T-cell-derived engineering, we examine the interactions of NK cells with other immune effectors and relevant signaling and the limitations in the tumor microenvironment, intending to understand how to enhance their cytolytic activities specifically for cancer immunotherapy.

High-dimensional analysis of NK cells in kidney transplantation uncovers subsets associated with antibody-independent graft dysfunction

Natural killer (NK) cells respond to diseased and allogeneic cells through NKG2A/HLA-E or killer cell immunoglobulin-like receptor (KIR)/HLA-ABC interactions. Correlations between HLA/KIR disparities and kidney transplant pathology suggest an antibody-independent pathogenic role for NK cells in transplantation, but the mechanisms remain unclear. Using CyTOF to characterize recipient peripheral NK cell phenotypes and function, we observed diverse NK cell subsets among participants who responded heterogeneously to allo-stimulators. NKG2A+KIR+ NK cells responded more vigorously than other subsets, and this heightened response persisted after kidney transplantation despite immunosuppression. In test and validation sets from 2 clinical trials, pretransplant donor-induced release of cytotoxicity mediator Ksp37 by NKG2A+ NK cells correlated with reduced long-term allograft function. Separate analyses showed that Ksp37 gene expression in allograft biopsies lacking histological rejection correlated with death-censored graft loss. Our findings support an antibody-independent role for NK cells in transplant injury and support further testing of pretransplant, donor-reactive, NK cell-produced Ksp37 as a risk-assessing, transplantation biomarker.

Genetic and functional diversity of allorecognition receptors in the urochordate, Botryllus schlosseri

Allorecognition in Botryllus schlosseri is controlled by a highly polymorphic locus (the fuhc), and functionally similar to missing-self recognition utilized by Natural Killer cells-compatibility is determined by sharing a self-allele, and integration of activating and inhibitory signals determines outcome. We had found these signals were generated by two fuhc-encoded receptors, called fester and uncle fester. Here we show that fester genes are members of an extended family consisting of >37 loci, and co-expressed with an even more diverse gene family-the fester co-receptors (FcoR). The FcoRs are membrane proteins related to fester, but include conserved tyrosine motifs, including ITIMs and hemITAMs. Both genes are encoded in highly polymorphic haplotypes on multiple chromosomes, revealing an unparalleled level of diversity of innate receptors. Our results also suggest that ITAM/ITIM signal integration is a deeply conserved mechanism that has allowed convergent evolution of innate and adaptive cell-based recognition systems.

The interaction of innate immune and adaptive immune system

The innate immune system serves as the body's first line of defense, utilizing pattern recognition receptors like Toll-like receptors to detect pathogens and initiate rapid response mechanisms. Following this initial response, adaptive immunity provides highly specific and sustained killing of pathogens via B cells, T cells, and antibodies. Traditionally, it has been assumed that innate immunity activates adaptive immunity; however, recent studies have revealed more complex interactions. This review provides a detailed dissection of the composition and function of the innate and adaptive immune systems, emphasizing their synergistic roles in physiological and pathological contexts, providing new insights into the link between these two forms of immunity. Precise regulation of both immune systems at the same time is more beneficial in the fight against immune-related diseases, for example, the cGAS-STING pathway has been found to play an important role in infections and cancers. In addition, this paper summarizes the challenges and future directions in the field of immunity, including the latest single-cell sequencing technologies, CAR-T cell therapy, and immune checkpoint inhibitors. By summarizing these developments, this review aims to enhance our understanding of the complexity interactions between innate and adaptive immunity and provides new perspectives in understanding the immune system.

Revolutionizing Cancer Treatment: Recent Advances in Immunotherapy

Cancer immunotherapy has emerged as a transformative approach in oncology, utilizing the body's immune system to specifically target and destroy malignant cells. This review explores the scope and impact of various immunotherapeutic strategies, including monoclonal antibodies, chimeric antigen receptor (CAR)-T cell therapy, checkpoint inhibitors, cytokine therapy, and therapeutic vaccines. Monoclonal antibodies, such as Rituximab and Trastuzumab, have revolutionized treatment paradigms for lymphoma and breast cancer by offering targeted interventions that reduce off-target effects. CAR-T cell therapy presents a potentially curative option for refractory hematologic malignancies, although challenges remain in effectively treating solid tumors. Checkpoint inhibitors have redefined the management of cancers like melanoma and lung cancer; however, managing immune-related adverse events and ensuring durable responses are critical areas of focus. Cytokine therapy continues to play a vital role in modulating the immune response, with advancements in cytokine engineering improving specificity and reducing systemic toxicity. Therapeutic vaccines, particularly mRNA-based vaccines, represent a frontier in personalized cancer treatment, aiming to generate robust, long-lasting immune responses against tumor-specific antigens. Despite these advancements, the field faces significant challenges, including immune resistance, tumor heterogeneity, and the immunosuppressive tumor microenvironment. Future research should address these obstacles through emerging technologies, such as next-generation antibodies, Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-based gene editing, and AI-driven drug discovery. By integrating these novel approaches, cancer immunotherapy holds the promise of offering more durable, less toxic, and highly personalized treatment options, ultimately improving patient outcomes and survival rates.

Monkeypox (Mpox) vs. Innate immune responses: Insights into evasion mechanisms and potential therapeutic strategies

Orthopoxviruses, a group of zoonotic viral infections, have emerged as a significant health emergency and global concern, particularly exemplified by the re-emergence of monkeypox (Mpox). Effectively addressing these viral infections necessitates a comprehensive understanding of the intricate interplay between the viruses and the host's immune response. In this review, we aim to elucidate the multifaceted aspects of innate immunity in the context of orthopoxviruses, with a specific focus on monkeypox virus (MPXV). We provide an in-depth analysis of the roles of key innate immune cells, including natural killer (NK) cells, dendritic cells (DCs), and granulocytes, in the host defense against MPXV. Furthermore, we explore the interferon (IFN) response, highlighting the involvement of toll-like receptors (TLRs) and cytosolic DNA/RNA sensors in detecting and responding to the viral presence. This review also examines the complement system's contribution to the immune response and provides a detailed analysis of the immune evasion strategies employed by MPXV to evade host defenses. Additionally, we discuss current prevention and treatment strategies for Mpox, including pre-exposure (PrEP) and post-exposure (PoEP) prophylaxis, supportive treatments, antivirals, and vaccinia immune globulin (VIG).

Distinct granzyme k expression in immune cells: a single-cell rna-seq meta-analysis

BACKGROUND

Granzymes are essential serine proteases in cytotoxic T cells and natural killer (NK) cells, with GZMK's expression being less understood. This study aims to uncover GZMK expression profiles across various immune cell types using single-cell RNA sequencing meta-analysis.

OBJECTIVE

This study aims to uncover GZMK expression profiles across various immune cell types using single-cell RNA sequencing meta-analysis.

METHODS

We conducted a meta-analysis using cellxgene, an interactive data exploration platform developed by the Chan Zuckerberg Initiative. We focused on mature T cells, NK cells, B cells, and NKT cells. We also checked transcription factor binding sites at the granzyme gene promoter regions using JASPAR. Comparative analysis was also done using mouse single-cell RNA sequencing data.

RESULTS

GZMK was the most lowly expressed in NK cells and mature NKT cells in most tissues except for colon and lymph nodes. In mature T cells, GZMK is similarly or more highly expressed than other granzymes. HBCA data revealed weak expression of GZMK in NK cells but strong expression in effector memory CD8-positive, alpha-beta T cells. Combined data shows no significant difference in GZMK expression between cell types. Subtype analysis shows that GZMK expression was higher in CD16-negative, CD56-bright NK cells when compared to CD16-positive, CD56-dim NK cells. We also identified unique transcription factor binding sites for GZMK. While this pattern in mouse data with low Gzmk expression in NK cells and higher T cells was repeated.

CONCLUSION

GZMK expression is distinctively regulated among immune cells and tissues, with unique promoter regions and transcription factor binding sites contributing to this differential expression. These insights into GZMK's role in immune function and regulation offer potential therapeutic targets.

Fasting reshapes tissue-specific niches to improve NK cell-mediated anti-tumor immunity

Fasting is associated with improved outcomes in cancer. Here, we investigated the impact of fasting on natural killer (NK) cell anti-tumor immunity. Cyclic fasting improved immunity against solid and metastatic tumors in an NK cell-dependent manner. During fasting, NK cells underwent redistribution from peripheral tissues to the bone marrow (BM). In humans, fasting also reduced circulating NK cell numbers. NK cells in the spleen of fasted mice were metabolically rewired by elevated concentrations of fatty acids and glucocorticoids, augmenting fatty acid metabolism via increased expression of the enzyme CPT1A, and Cpt1a deletion impaired NK cell survival and function in this setting. In parallel, redistribution of NK cells to the BM during fasting required the trafficking mediators S1PR5 and CXCR4. These cells were primed by an increased pool of interleukin (IL)-12-expressing BM myeloid cells, which improved IFN-γ production. Our findings identify a link between dietary restriction and optimized innate immune responses, with the potential to enhance immunotherapy strategies.

Human esophageal cancer stem-like cells escape the cytotoxicity of natural killer cells via down-regulation of ULBP-1

BACKGROUND

Cancer stem-like cells (CSCs) play an important role in initiation and progression of aggressive cancers, including esophageal cancer. Natural killer (NK) cells are key effector lymphocytes of innate immunity that directly attack a wide variety of cancer cells. NK cell-based therapy may provide a new treatment option for targeting CSCs. In this study, we aimed to investigate the sensitivity of human esophageal CSCs to NK cell-mediated cytotoxicity.

METHODS

CSCs were enriched from human esophageal squamous cell carcinoma cell lines via sphere formation culture. Human NK cells were selectively expanded from the peripheral blood of healthy donors. qRT-PCR, flow cytometry and ELISA assays were performed to examine RNA expression and protein levels, respectively. CFSE-labeled target cells were co-cultured with human activated NK cells to detect the cytotoxicity of NK cells by flow cytometry.

RESULTS

We observed that esophageal CSCs were more resistant to NK cell-mediated cytotoxicity compared with adherent counterparts. Consistently, esophageal CSCs showed down-regulated expression of ULBP-1, a ligand for NK cells stimulatory receptor NKG2D. Knockdown of ULBP-1 resulted in significant inhibition of NK cell cytotoxicity against esophageal CSCs, whereas ULBP-1 overexpression led to the opposite effect. Finally, the pro-differentiation agent all-trans retinoic acid was found to enhance the sensitivity of esophageal CSCs to NK cell cytotoxicity.

CONCLUSIONS

This study reveals that esophageal CSCs are more resistant to NK cells through down-regulation of ULBP-1 and provides a promising approach to promote the activity of NK cells targeting esophageal CSCs.

In-depth analysis of the interplay between oncogenic mutations and NK cell-mediated cancer surveillance in solid tumors

Natural killer (NK) cells play a crucial role in antitumoral and antiviral responses. Yet, cancer cells can alter themselves or the microenvironment through the secretion of cytokines or other factors, hindering NK cell activation and promoting a less cytotoxic phenotype. These resistance mechanisms, often referred to as the "hallmarks of cancer" are significantly influenced by the activation of oncogenes, impacting most, if not all, of the described hallmarks. Along with oncogenes, other types of genes, the tumor suppressor genes are frequently mutated or modified during cancer. Traditionally, these genes have been associated with uncontrollable tumor growth and apoptosis resistance. Recent evidence suggests oncogenic mutations extend beyond modulating cell death/proliferation programs, influencing cancer immunosurveillance. While T cells have been more studied, the results obtained highlight NK cells as emerging key protagonists for enhancing tumor cell elimination by modulating oncogenic activity. A few recent studies highlight the crucial role of oncogenic mutations in NK cell-mediated cancer recognition, impacting angiogenesis, stress ligands, and signaling balance within the tumor microenvironment. This review will critically examine recent discoveries correlating oncogenic mutations to NK cell-mediated cancer immunosurveillance, a relatively underexplored area, particularly in the era dominated by immune checkpoint inhibitors and CAR-T cells. Building on these insights, we will explore opportunities to improve NK cell-based immunotherapies, which are increasingly recognized as promising alternatives for treating low-antigenic tumors, offering significant advantages in terms of safety and manufacturing suitability.

Inhibition of NK cell cytotoxicity by tubular epithelial cell expression of Clr-b and Clr-f

NK cells participate in ischemia reperfusion injury (IRI) and transplant rejection. Endogenous regulatory systems may exist to attenuate NK cell activation and cytotoxicity in IRI associated with kidney transplantation. A greater understanding of NK regulation will provide insights in transplant outcomes and could direct new therapeutic strategies. Kidney tubular epithelial cells (TECs) may negatively regulate NK cell activation by their surface expression of a complex family of C-type lectin-related proteins (Clrs). We have found that Clr-b and Clr-f were expressed by TECs. Clr-b was upregulated by inflammatory cytokines TNFα and IFNγ in vitro. Silencing of both Clr-b and Clr-f expression using siRNA resulted in increased NK cell killing of TECs compared to silencing of either Clr-b or Clr-f alone (p < 0.01) and when compared to control TECs (p < 0.001). NK cells treated in vitro with soluble Clr-b and Clr-f proteins reduced their capacity to kill TECs (p < 0.05). Hence, NK cell cytotoxicity can be inhibited by Clr proteins on the surface of TECs. Our study suggests a synergistic effect of Clr molecules in regulating NK cell function in renal cells and this may represent an important endogenous regulatory system to limit NK cell-mediated organ injury during inflammation.

Spleen Tyrosine Kinase (SYK) negatively regulates ITAM-mediated human NK cell signaling and CD19-CAR NK cell efficacy

NK cells express activating receptors that signal through ITAM-bearing adapter proteins. The phosphorylation of each ITAM creates binding sites for SYK and ZAP70 protein tyrosine kinases to propagate downstream signaling including the induction ofCa 2 + influx. While all immature and mature human NK cells co-express SYK and ZAP70, clonally driven memory or adaptive NK cells can methylate SYK genes and signaling is mediated exclusively using ZAP70. Here, we examined the role of SYK and ZAP70 in a clonal human NK cell line KHYG1 by CRISPR-based deletion using a combination of experiments and mechanistic computational modeling. Elimination of SYK resulted in more robustCa + + influx after cross-linking of the CD16 and NKp30 receptors and enhanced phosphorylation of downstream proteins, whereas ZAP70 deletion diminished these responses. By contrast, ZAP70 depletion increased proliferation of the NK cells. As immature T cells express both SYK and ZAP70 but mature T cells often express only ZAP70, we transduced the human Jurkat cell line with SYK and found that expression of SYK increased proliferation but diminished TCR-inducedCa 2 + flux and activation. We performed transcriptional analysis of the matched sets of variant Jurkat and KHYG1 cells and observed profound alterations caused by SYK expression. As depletion of SYK in NK cells increased their activation, primary human NK cells were transduced with a CD19-targeting CAR and were CRISPR edited to ablate SYK or ZAP70. Deletion of SYK resulted in more robust cytotoxic activity and cytokine production, providing a new therapeutic strategy of NK cell engineering for cancer immunotherapy.

NK-like CD8 T cell: one potential evolutionary continuum between adaptive memory and innate immunity

CD8 T cells are crucial adaptive immune cells with cytotoxicity to fight against pathogens or abnormal self-cells via major histocompatibility complex class I-dependent priming pathways. The composition of the memory CD8 T-cell pool is influenced by various factors. Physiological aging, chronic viral infection, and autoimmune diseases promote the accumulation of CD8 T cells with highly differentiated memory phenotypes. Accumulating studies have shown that some of these memory CD8 T cells also exhibit innate-like cytotoxicity and upregulate the expression of receptors associated with natural killer (NK) cells. Further analysis shows that these NK-like CD8 T cells have transcriptional profiles of both NK and CD8 T cells, suggesting the transformation of CD8 T cells into NK cells. However, the specific induction mechanism underlying NK-like transformation and the implications of this process for CD8 T cells are still unclear. This review aimed to deduce the possible differentiation model of NK-like CD8 T cells, summarize the functions of major NK-cell receptors expressed on these cells, and provide a new perspective for exploring the role of these CD8 T cells in health and disease.

IFNγ mediates the resistance of tumor cells to distinct NK cell subsets

BACKGROUND

Immune checkpoint blockade targeting the adaptive immune system has revolutionized the treatment of cancer. Despite impressive clinical benefits observed, patient subgroups remain non-responsive underscoring the necessity for combinational therapies harnessing additional immune cells. Natural killer (NK) cells are emerging tools for cancer therapy. However, only subpopulations of NK cells that are differentially controlled by inhibitory receptors exert reactivity against particular cancer types. How to leverage the complete anti-tumor potential of all NK cell subsets without favoring the emergence of NK cell-resistant tumor cells remains unresolved.

METHODS

We performed a genome-wide CRISPR/Cas9 knockout resistance screen in melanoma cells in co-cultures with human primary NK cells. We comprehensively evaluated factors regulating tumor resistance and susceptibility by focusing on NK cell subsets in an allogenic setting. Moreover, we tested therapeutic blocking antibodies currently used in clinical trials.

RESULTS

Melanoma cells deficient in antigen-presenting or the IFNγ-signaling pathways were depleted in remaining NK cell-co-cultured melanoma cells and displayed enhanced sensitivity to NK cells. Treatment with IFNγ induced potent resistance of melanoma cells to resting, IL-2-cultured and ADCC-activated NK cells that depended on B2M required for the expression of both classical and non-classical MHC-I. IFNγ-induced expression of HLA-E mediated the resistance of melanoma cells to the NKG2A+ KIR- and partially to the NKG2A+ KIR+ NK cell subset. The expression of classical MHC-I by itself was sufficient for the inhibition of the NKG2A- KIR+, but not the NKG2A+ KIR+ NK cell subset. Treatment of NK cells with monalizumab, an NKG2A blocking mAb, enhanced the reactivity of a corresponding subset of NK cells. The combination of monalizumab with lirilumab, blocking KIR2 receptors, together with DX9, blocking KIR3DL1, was required to restore cytotoxicity of all NK cell subsets against IFNγ-induced resistant tumor cells in melanoma and tumors of different origins.

CONCLUSION

Our data reveal that in the context of NK cells, IFNγ induces the resistance of tumor cells by the upregulation of classical and non-classical MHC-I. Moreover, we reveal insights into NK cell subset reactivity and propose a therapeutic strategy involving combinational monalizumab/lirilumab/DX9 treatment to fully restore the antitumor response across NK cell subsets.

Innate Allorecognition in Transplantation: Ancient Mechanisms With Modern Impact

Through the effective targeting of the adaptive immune system, solid organ transplantation became a life-saving therapy for organ failure. However, beyond 1 y of transplantation, there is little improvement in transplant outcomes. The adaptive immune response requires the activation of the innate immune system. There are no modalities for the specific targeting of the innate immune system involvement in transplant rejection. However, the recent discovery of innate allorecognition and innate immune memory presents novel targets in transplantation that will increase our understanding of organ rejection and might aid in improving transplant outcomes. In this review, we look at the latest developments in the study of innate allorecognition and innate immune memory in transplantation.

Efficiently targeting neuroblastoma with the combination of anti-ROR1 CAR NK cells and N-803 in vitro and in vivo in NB xenografts

The prognosis for children with recurrent and/or refractory neuroblastoma (NB) is dismal. The receptor tyrosine kinase-like orphan receptor 1 (ROR1), which is highly expressed on the surface of NB cells, provides a potential target for novel immunotherapeutics. Anti-ROR1 chimeric antigen receptor engineered ex vivo expanded peripheral blood natural killer (anti-ROR1 CAR exPBNK) cells represent this approach. N-803 is an IL-15 superagonist with enhanced biological activity. In this study, we investigated the in vitro and in vivo anti-tumor effects of anti-ROR1 CAR exPBNK cells with or without N-803 against ROR1+ NB models. Compared to mock exPBNK cells, anti-ROR1 CAR exPBNK cells had significantly enhanced cytotoxicity against ROR1+ NB cells, and N-803 further increased cytotoxicity. High-dimensional analysis revealed that N-803 enhanced Stat5 phosphorylation and Ki67 levels in both exPBNK and anti-ROR1 CAR exPBNK cells with or without NB cells. In vivo, anti-ROR1 CAR exPBNK plus N-803 significantly (p < 0.05) enhanced survival in human ROR1+ NB xenografted NSG mice compared to anti-ROR1 CAR exPBNK alone. Our results provide the rationale for further development of anti-ROR1 CAR exPBNK cells plus N-803 as a novel combination immunotherapeutic for patients with recurrent and/or refractory ROR1+ NB.

Upregulation of the NKG2D Ligand ULBP2 by JC Polyomavirus Infection Promotes Immune Recognition by Natural Killer Cells

BACKGROUND

JC polyomavirus (JCPyV) causes progressive multifocal leukoencephalopathy (PML), a potentially fatal complication of severe immune suppression with no effective treatment. Natural killer (NK) cells play critical roles in defense against viral infections; however, NK-cell response to JCPyV infection remains unexplored.

METHODS

NK- and T-cell responses against the JCPyV VP1 were compared using intracellular cytokine staining upon stimulation with peptide pools. A novel flow cytometry-based assay was developed to determine NK-cell killing efficiency of JCPyV-infected astrocyte-derived SVG-A cells. Blocking antibodies were used to evaluate the contribution of NK-cell receptors in immune recognition of JCPyV-infected cells.

RESULTS

In about 40% of healthy donors, we detected robust CD107a upregulation and IFN-γ production by NK cells, extending beyond T-cell responses. Next, using the NK-cell-mediated killing assay, we showed that coculture of NK cells and JCPyV-infected SVG-A cells leads to a 60% reduction in infection, on average. JCPyV-infected cells had enhanced expression of ULBP2-a ligand for the activating NK-cell receptor NKG2D, and addition of NKG2D blocking antibodies decreased NK-cell degranulation.

CONCLUSIONS

NKG2D-mediated activation of NK cells plays a key role in controlling JCPyV replication and may be a promising immunotherapeutic target to boost NK-cell anti-JCPyV activity.

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

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

Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3+ T cells in tuberculosis patients

BACKGROUND

Human T cells play an important role in immunity against tuberculosis (TB) infection. Activating receptor HLA-DR and inhibitory receptor KLRG1 are critical regulators of T cell function during viral infection and tumorigenesis, but they have been less studied in TB infection.

METHODS

In this study, we explored the relationship between CD3+ T cell expression of HLA-DR and KLRG1 receptors and function against TB infection. Flow cytometry was conducted to assess the immunomodulatory effects of HLA-DR and KLRG1 receptors on CD3+ T cells in patients with different TB infection status.

RESULTS

We found activating receptors HLA-DR, NKG2C, CD57 and NKP46, and inhibitory receptors KLRG1 and KIR on CD3+ T cells in different TB infection status showed different distribution patterns; the cytotoxic potential and cytokine secretion capacity of CD3+ T cells after Mtb-specific antigen stimulation were significantly enhanced in TB infection groups. Further studies revealed HLA-DR+ T and KLRG1+ T cells expressed higher activating and inhibitory receptors than the negative population. In addition, the expression of cytotoxic potential and cytokine secretion capacity of HLA-DR+ T and KLRG1+ T cells was significantly higher than that of HLA-DR- T and KLRG1- T cells.

CONCLUSIONS

Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3+ T cells in TB patients, suggesting CD3+ T cells expressing HLA-DR and KLRG1 are important effector cell phenotypes involved in the host anti-TB infection. HLA-DR and KLRG1 expressed by CD3+ T cells may be potential predictive markers of TB disease progression and clinical immune assessment.

Induced CD8α identifies human NK cells with enhanced proliferative fitness and modulates NK cell activation

The surface receptor CD8α is present on 20%-80% of human (but not mouse) NK cells, yet its function on NK cells remains poorly understood. CD8α expression on donor NK cells was associated with a lack of therapeutic responses in patients with leukemia in prior studies, thus, we hypothesized that CD8α may affect critical NK cell functions. Here, we discovered that CD8α- NK cells had improved control of leukemia in xenograft models compared with CD8α+ NK cells, likely due to an enhanced capacity for proliferation. Unexpectedly, we found that CD8α expression was induced on approximately 30% of previously CD8α- NK cells following IL-15 stimulation. These induced CD8α+ (iCD8α+) NK cells had the greatest proliferation, responses to IL-15 signaling, and metabolic activity compared with those that sustained existing CD8α expression (sustained CD8α+) or those that remained CD8α- (persistent CD8α-). These iCD8α+ cells originated from an IL-15Rβhi NK cell population, with CD8α expression dependent on the transcription factor RUNX3. Moreover, CD8A CRISPR/Cas9 deletion resulted in enhanced responses through the activating receptor NKp30, possibly by modulating KIR inhibitory function. Thus, CD8α status identified human NK cell capacity for IL-15-induced proliferation and metabolism in a time-dependent fashion, and its presence had a suppressive effect on NK cell-activating receptors.