Natural Killer Cell Cytotoxicity Research Articles

Multi-omics reveal immune microenvironment alterations in multiple myeloma and its precursor stages.

Tumor immune microenvironmental alterations occur early in multiple myeloma (MM) development. In this study, we aim to systematically characterize the tumor immune microenvironment (TME) and the tumor-immune interactions from precursor stages, i.e., monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM), to newly diagnosed MM, comparing these to healthy donors. Using CIBERSORT, mass cytometry (CyTOF), and single-cell RNA sequencing (scRNA-Seq), we examined innate and adaptive immune changes across these stages. We found a decrease in granulocytes in the TME predicts MM outcomes. HLA-DR is reduced in CD16+ monocytes and plasmacytoid dendritic cells, while myeloid dendritic cells show decreased expression of stress and immune-response genes. NK cells and CD8+ T cells shift from a GZMK+ to a GZMB+ cytotoxic phenotype in the TME, with increased inhibitory markers TIM3 and TIGIT. In paired samples, the proportion and gene expression pattern in patient-specific GZMB+CD8+ T cells remain largely unchanged despite MM progression. Our findings provide a comprehensive immune landscape of MM and its precursors, offering insights into therapeutic strategies. Enhancing neutrophil and NK cell cytotoxicity, tumor antigen presentation, and CD8+ T cell versatility in precursor stages may prevent MM progression.

Effect of NK cell receptor genetic variation on allogeneic stem cell transplantation outcome and in vitro NK cell cytotoxicity.

Natural killer (NK) cells recognize and may kill malignant cells via their cell surface receptors. Killer cell immunoglobulin-like receptor (KIR) genotypes of donors have been reported to adjust the risk of relapse after allogeneic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia. To test whether non-KIR NK cell receptors have a similar effect, we screened 1,638 genetic polymorphisms in 21 non-KIR NK cell receptor genes for their associations with relapse and graft-versus-host disease (GVHD) after HSCT in 1,491 HSCT donors (from Finland, the UK, Spain, and Poland), divided into a discovery and replication cohort. Eleven polymorphisms regulating or located in CD226, CD244, FCGR3A, KLRD1, NCR3, and PVRIG were associated with the risks for relapse and GVHD. These associations could not be confirmed in the replication cohort. Blood donor NK cells carrying alleles showing genetic protection for relapse had a higher in vitro NK cell killing activity than non-carriers whereas those with alleles genetically protective for GVHD had lower cytotoxicity, potentially indicating functional effects. Taken together, these results show no robust effects of genetic variation in the tested non-KIR NK cell receptors on the outcome of HSCT.

Metabolic programs drive function of therapeutic NK cells in hypoxic tumor environments.

Limited oxygen (hypoxia) in solid tumors poses a challenge to successful immunotherapy with natural killer (NK) cells. NK cells have impaired cytotoxicity when cultured in hypoxia (1% oxygen) but not physiologic (>5%) or atmospheric oxygen (20%). We found that changes to cytotoxicity were regulated at the transcriptional level and accompanied by metabolic dysregulation. Dosing with interleukin-15 (IL-15) enhanced NK cell cytotoxicity in hypoxia, but preactivation with feeder cells bearing IL-21 and 4-1BBL was even better. Preactivation resulted in less perturbed metabolism in hypoxia; greater resistance to oxidative stress; and no hypoxia-induced loss of transcription factors (T-bet and Eomes), activating receptors, adhesion molecules (CD2), and cytotoxic proteins (TRAIL and FasL). There remained a deficit in CD122/IL-2Rβ when exposed to hypoxia, which affected IL-15 signaling. However, tri-specific killer engager molecules that deliver IL-15 in the context of anti-CD16/FcγRIII were able to bypass this deficit, enhancing cytotoxicity of both fresh and preactivated NK cells in hypoxia.

Potential treatment approaches for malignant peritoneal mesothelioma: in vivo and in vitro experimental study of natural killer cell immunotherapy.

Malignant peritoneal mesothelioma (MPM) is a rare primary malignant tumor with an extremely poor prognosis that currently lacks effective treatment options. This study investigated the in vitro and in vivo efficacy of natural killer (NK) cells for treatment of MPM. An in vitro study was conducted to assess the cytotoxicity of NK cells from umbilical cord blood to MPM cells with the use of a high-content imaging analysis system, the Cell Counting Kit-8 assay, and Wright-Giemsa staining. The level of NK cell effector molecule expression was detected by flow cytometry and enzyme-linked immunosorbent assays. The ability of NK cells to kill MPM cells was determined based on live cell imaging, transmission electron microscopy, and scanning electron microscopy. An in vivo study was conducted to assess the efficacy and safety of NK cell therapy based on the experimental peritoneal cancer index, small animal magnetic resonance imaging, and conventional histopathologic, cytologic, and hematologic studies. NK cells effectively killed MPM cells through the release of effector molecules (granzyme B, perforin, interferon-γ, and tumor necrosis factor-α) in a dose- and density-dependent manner. The NK cell killing process potentially involved four dynamic steps: chemotaxis; hitting; adhesion; and penetration. NK cells significantly reduced the tumor burden, diminished ascites production, and extended survival with no significant hematologic toxicity or organ damage in NOG mice. NK cell immunotherapy inhibited proliferation of MPM cells in vitro and in vivo with a good safety profile.

PEDV evades MHC-I-related immunity through nsp1-mediated NLRC5 translation inhibition.

Major histocompatibility complex class I (MHC-I) plays crucial roles against viral infections not only by initiating CD8+ T cell immunity but also by modulating natural killer (NK) cell cytotoxicity. Understanding how viruses precisely regulate MHC-I to optimize their infection is important; however, the manipulation of MHC-I molecules by porcine epidemic diarrhea virus (PEDV) remains unclear. In this study, we demonstrate that PEDV infection promotes the transcription of NLRC5, a key transactivator of MHC-I, in several porcine cell lines and in vivo. Paradoxically, no increase in MHC-I expression is observed after PEDV infection both in vitro and in vivo. Mechanistic studies revealed that PEDV infection inhibits the translation of PEDV-elicited NLRC5 mRNA and the expression of downstream MHC-I proteins, without affecting the expression of physiological NLRC5 and MHC-I proteins. Through viral protein screening, we identified PEDV nonstructural protein 1 (nsp1) as the critical antagonist that inhibits NLRC5-mediated upregulation of MHC-I, and the nsp1's inhibitory effect on MHC-I requires the motif of 15 amino acids at its C-terminus. Notably, our results revealed that the cytotoxic ability of NK cells against PEDV-infected cells is similar to that against healthy cells. Collectively, our findings uncover an immune evasion mechanism by which PEDV-infected cells masquerade as healthy cells to evade NK and T cell immunity. This is achieved by targeting NLRC5, a key MHC-I transcriptional regulator, via nsp1.IMPORTANCEPorcine epidemic diarrhea virus (PEDV) is a highly contagious enteric coronavirus that inflicts substantial financial losses on the swine industry. Major histocompatibility complex class I (MHC-I) is a critical factor influencing both CD8+ T cell and natural killer (NK) cell immunity. However, how PEDV manipulates MHC-I expression to optimize its infection process remains largely unknown. In this study, we demonstrate that PEDV's nonstructural protein 1 (nsp1) inhibits virus-mediated induction of MHC-I expression by directly targeting NLRC5, a key MHC-I transactivator. Intriguingly, nsp1 does not reduce physiological NLRC5 and MHC-I expression. This selective inhibition of virus-elicited NLRC5 mRNA translation allows PEDV-infected cells to masquerade as healthy cells, thereby evading CD8+ T cell and NK cell cytotoxicity. Our findings provide unique insights into the mechanisms by which PEDV evades CD8+ T cell and NK cell immunity.

Longitudinal transcriptional changes reveal genes from the natural killer cell-mediated cytotoxicity pathway as critical players underlying COVID-19 progression

Patients present a wide range of clinical severities in response severe acute respiratory syndrome coronavirus 2 infection, but the underlying molecular and cellular reasons why clinical outcomes vary so greatly within the population remains unknown. Here, we report that negative clinical outcomes in severely ill patients were associated with divergent RNA transcriptome profiles in peripheral immune cells compared with mild cases during the first weeks after disease onset. Protein–protein interaction analysis indicated that early-responding cytotoxic natural killer cells were associated with an effective clearance of the virus and a less severe outcome. This innate immune response was associated with the activation of select cytokine–cytokine receptor pathways and robust Th1/Th2 cell differentiation profiles. In contrast, severely ill patients exhibited a dysregulation between innate and adaptive responses affiliated with divergent Th1/Th2 profiles and negative outcomes. This knowledge forms the basis of clinical triage that may be used to preemptively detect high-risk patients before life-threatening outcomes ensue.

Longitudinal transcriptional changes reveal genes from the natural killer cell-mediated cytotoxicity pathway as critical players underlying COVID-19 progression.

Patients present a wide range of clinical severities in response severe acute respiratory syndrome coronavirus 2 infection, but the underlying molecular and cellular reasons why clinical outcomes vary so greatly within the population remains unknown. Here, we report that negative clinical outcomes in severely ill patients were associated with divergent RNA transcriptome profiles in peripheral immune cells compared with mild cases during the first weeks after disease onset. Protein-protein interaction analysis indicated that early-responding cytotoxic natural killer cells were associated with an effective clearance of the virus and a less severe outcome. This innate immune response was associated with the activation of select cytokine-cytokine receptor pathways and robust Th1/Th2 cell differentiation profiles. In contrast, severely ill patients exhibited a dysregulation between innate and adaptive responses affiliated with divergent Th1/Th2 profiles and negative outcomes. This knowledge forms the basis of clinical triage that may be used to preemptively detect high-risk patients before life-threatening outcomes ensue.

Effect of Hypoxia on Siglec-7 and Siglec-9 Receptors and Sialoglycan Ligands and Impact of Their Targeting on NK Cell Cytotoxicity

Background/Objectives: Tumor microenvironmental hypoxia is an established hallmark of solid tumors. It significantly contributes to tumor aggressiveness and therapy resistance and has been reported to affect the balance of activating/inhibitory surface receptors’ expression and activity on NK cells. In the current study, we investigated the impact of hypoxia on the surface expression of Siglec-7 and Siglec-9 (Sig-7/9) and their ligands in NK cells and tumor target cells. The functional consequence of Siglec blockage using nanoparticles specifically designed to target and block Sig-7/9 receptors on NK cell cytotoxicity was elucidated. Methods: CD56⁺ CD3− NK cells were isolated from PBMCs along with an NK-92 clone and used as effector cells, while MCF-7 and K562 served as target cells. All cells were incubated under normoxic or hypoxic conditions for 24 h. To assess Siglec-7 and Siglec-9 receptor expression, U937, NK-92, and primary NK cells were stained with PE-labeled antibodies against CD328 Siglec-7/9. Interactions between Siglec-7/9 and their sialylated ligands, along with their functional impact on NK cell activity, were evaluated using polymeric nanoparticles coated with a sialic acid mimetic. Immunological synapse formation and live-cell imaging were performed with a ZEISS LSM 800 with Airyscan at 10x magnification for 24 h. Results: Our data indicate that hypoxia had no effect on the expression of Siglec-7/9 receptors by NK cells. In contrast, hypoxic stress resulted in an increase in Siglec-7 sialoglycan ligand expression by a sub-population of NK target cells. Using polymeric nanoparticles coated with a sialic acid mimetic that binds both Siglec-7 and -9 (Sig-7/9 NP), we demonstrated that incubation of these nanoparticles with NK cells resulted in increased immunological synapse formation, granzyme B accumulation, and killing of NK target cells. These studies indicate that hypoxic stress may have an impact on NK cell-based therapies and highlight the need to consider the hypoxic microenvironment for tumor-specific glycosylation. Conclusions: Our findings point to the role of Siglec–sialylated glycan interactions in hypoxic stress-induced NK cell dysfunction and recommend the potential integration of the manipulation of this axis through the targeting of Siglecs in future cancer immunotherapy strategies.

Single-cell RNA sequencing uncovers molecular mechanisms of intravenous immunoglobulin plus methylprednisolone in Kawasaki disease: attenuated monocyte-driven inflammation and improved NK cell cytotoxicity

IntroductionIntravenous immunoglobulin (IVIG) plus methylprednisolone as initial intensive therapy or additional therapy in Kawasaki disease (KD) has been used in clinical practice. However, its molecular and cellular mechanism is unclear.MethodsWe performed single-cell analysis on 14 peripheral blood mononuclear cell (PBMC) samples obtained from 7 KD patients who received either IVIG monotherapy or IVIG plus methylprednisolone therapy. This encompassed 4 samples from KD patients collected before and after IVIG treatment, as well as 3 samples from KD patients before and after IVIG plus methylprednisolone therapy.ResultsBoth IVIG monotherapy and IVIG plus methylprednisolone therapy can increase lymphocyte counts (e.g. CD4+T, CD8+T, and gdT cells) to address lymphopenia. They can also decrease monocyte counts and repress the expression of S100A12, NLRP3, and genes associated with immune-cell migration in monocytes. IVIG combined with methylprednisolone downregulates more monocyte-driven inflammatory pathways than IVIG alone. Additionally, this combination uniquely enhances NK cell cytotoxicity by modulating receptor homeostasis, while significantly upregulating interferon-related genes in CD4+ T cells, CD8+ T cells, and B cells, particularly type I interferons.ConclusionThe combination of IVIG with methylprednisolone attenuated monocyte-driven inflammation and improved NK cell cytotoxicity which might provide clues for pediatricians to consider treatment options for children with KD. Whether the monocyte-driven hyperinflammatory state and NK cell function can be indicators for the clinical choice of IVIG with methylprednisolone therapy in KD needs further investigation.

CD56 does not contribute to the anti-tumor, tissue homing, and glycolytic capacity of human NK cells.

Natural Killer (NK) cells are critical innate immune cells involved in the clearance of virally infected and malignant cells. Human NK cells are distinguished by their surface expression of CD56 and a lack of CD3. While CD56 expression and cell surface density has long been used as the prototypic marker to characterize primary human NK cell functional subsets, the exact functional role of CD56 in primary human NK cells is still not fully understood. Here we eliminated the expression of CD56 in human ex vivo expanded NK cells (CD56bright) using CRISPR/Cas9 in order to assess the function of CD56 in this highly activated and cytotoxic NK cell population. We show that the expression of CD56 has no effect on NK cell proliferative capacity or expression of various activation and inhibitory markers. Further, CD56 does not contribute to NK cell-mediated cytotoxicity, inflammatory cytokine production, or the ability of NK cells to control tumor engraftment in vivo. We also found that while deletion of CD56 did not impact NK cell glycolytic metabolism it did increase NK cell reliance on oxidative phosphorylation. Lastly, CD56 does not alter expanded NK cell in vivo tissue trafficking. Our results indicate that while CD56 expression could be used to indicate a hyper-functional state of NK cells, it does not directly influence the anti-tumor functions of expanded NK cells.

Expression of Molecules Characterizing Metabolic and Cytotoxic Activity of Natural Killer Different Subpopulations of Peripheral Blood During Pregnancy

The functions of peripheral blood NK cells change significantly during pregnancy, which is mainly due to the inhibition of their cytotoxicity. The functional activity of NK cells is directly related to their metabolic status, but these changes in physiological pregnancy have not been studied. The aim of this work is to study the expression of Glut-1, CD94 and CD107a molecules characterizing metabolic and cytotoxic activity, as well as the mitochondrial mass of different subpopulations of peripheral blood NK cells in the I and III trimesters of physiological pregnancy. The object of the study was the peripheral blood of healthy women in the I and III trimesters of physiological pregnancy. The control group consisted of healthy non-pregnant women in the follicular phase of the menstrual cycle. The expression of Glut-1, CD94, CD107a molecules and the mitochondrial mass were analyzed by flow cytometry on regulatory (CD16–CD56bright), cytotoxic (CD16+CD56dim), minor cytotoxic (CD16hiCD56–) NK cells. It was found that in non-pregnant women, minor cytotoxic CD16hiCD56–NK have the highest expression of Glut-1, CD107a and the lowest expression of CD94 compared to other NK cell subpopulations. On regulatory CD16–CD 56bright and cytotoxic CD16+CD56dimNK, the expression of these molecules is comparable to each other. The mitochondrial mass is similar in all studied subpopulations. In the first trimester, the expression of Glut-1 increases on regulatory CD16–CD56brightNK, the mitochondrial mass and the expression of CD94, CD107a in all NK cells do not differ from non-pregnant ones. In the third trimester, the mitochondrial mass increases in cytotoxic CD16+CD56dimNK cells, but CD94 expression decreases compared to non-pregnant ones, and the expression CD94 in regulatory CD16–CD56brightNK increases compared to the first trimester. CD107a expression in minor cytotoxic CD16hiCD56–NK decreases, but in other subpopulations does not change compared to non-pregnant. The expression of Glut-1 does not change in all subpopulations. Thus, different subpopulations of peripheral blood NK cells are heterogeneous in the expression of Glut-1, CD107a, CD94. The expression of these molecules during physiological pregnancy varies by trimester. The obtained results are important for understanding the mechanisms of NK cell function regulations during pregnancy.

Abstract A052: RNF43 p.G659fs mutation in MSI-high colorectal cancer leads to natural killer cell dysfunction

Abstract RNF43_p.G659fsV*41 mutation (RNF43659mut) is found in approximately 8% of colorectal cancers (CRCs) and is enriched in microsatellite-instability high (MSI-high) tumors. Previously, we reported that RNF43659mut promotes tumor growth independent of WNT signaling and activates PI3K/AKT signaling in CRC, conferring vulnerability to PI3K/MTOR inhibition. In addition, RNF43659mut was associated with decreased interferon signaling suggesting a link with anti-tumor immunity. Thus, in the current work we investigated the role of RNF43659mut in CRC immunomodulation. The immune-cell landscape was evaluated in RNF43659mut compared with RNF43-wild type (wt) MSI-high CRCs in two cohorts; single-cell (sc)-RNA-sequencing data from treatment-naïve primary tumors from 34 patients (cohort-1) and multiplex immunofluorescence / whole exome sequencing data from an independent cohort of 91 patients (cohort-2). Healthy donor blood-derived natural killer (NK) cell responses and cytotoxicity were investigated in co-cultures with RNF43659mut isogenic tumor lines and with patient-derived organoids harboring RNF43659mut or overexpressing RNF43wt. A third patient cohort with MSI-high CRCs treated with immune checkpoint blockade was analyzed to understand the impact of RNF43659mut on immunotherapy efficacy. Interrogation of sc-RNASeq data in cohort-1 revealed a significant enrichment of NK cells in the RNF43659mut patient samples compared to the RNF43wt ones. This finding was also confirmed by multiplex immunofluorescence in cohort-2. Single-cell transcriptomic analyses in cohort-1 showed increased inhibitory markers on NK cells despite their enrichment in RNF43659mut tumors. RNAseq analysis of sorted NK cells co-cultured with RNF43659mut isogenic tumor lines further supported their dysfunctional state. Flow cytometric analyses of NK cell maturation, activation, and inhibitory markers in NK cells co-cultured with RNF43659mut isogenic tumor lines and organoids highlighted decreased levels of NCAM1 (CD56)dim and NCAM1 (CD56)bright subsets, FCGR3A (CD16), and KLRK1 (NKG2D), along with increased levels of KLRC1 (NKG2A), KIR3DL1 (NKB1) and TIGIT inhibitory markers. There was reduced NK cell mediated tumor cell killing in RNF43659mut isogenic tumor lines and organoids. We postulated that aberrant signaling of the PI3K/AKT pathway with RNF43659mut could lead to NK cell dysfunction. Indeed, siRNA-mediated blocking of PI3K/AKT pathway restored the NK-cell dysfunctional phenotype and tumor cell killing in co-cultures with RNF43659mut isogenic tumor lines and organoids. Conversely, overexpression of WT RNF43 in RNF43659mut organoids downregulated PI3K/AKT signaling and increased NK cell cytotoxicity. Lastly, MSI-high CRC tumors harboring RNF43659mut in patients treated with immunotherapy showed less benefit from immune checkpoint blockade. PI3K/AKT activation due to RNF43659mut in MSI-high CRC leads to NK cell dysfunction and reduced NK cell cytotoxicity. This could be responsible for immunotherapy failure, warranting further investigation. Citation Format: Pushpamali De Silva, Samantha Fitzgerald, Jules Cazaubiel, Matan Hofree, Tomotaka Ugai, Juha P Väyrynen, Dane Ford-Roshon, Lishan Fang, Ana Garrido-Castro, Nir Hacohen, Kimmie Ng, Shuji Ogino, Jonathan A Nowak, Marios Giannakis. RNF43 p.G659fs mutation in MSI-high colorectal cancer leads to natural killer cell dysfunction [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A052.

Assessment of NK cytotoxicity and interactions with porcine endothelial cells by live-cell imaging in 2D static and 3D microfluidic systems

Natural Killer (NK) cells are pivotal in immune responses to viral infections, malignancies, autoimmune diseases, and transplantation. Assessment of NK cell adhesion, migration, and cytotoxicity is fundamental for in vitro studies. We propose a novel live-cell tracking method that addresses these three major aspects of NK cell function using human NK cells and primary porcine aortic endothelial cells (PAECs) in two-dimensional (2D) static assays and an in-house cylindrical 3D microfluidic system. The results showed a significant increase of NK cytotoxicity against pTNF-activated PAECs, with apoptotic cell death observed in the majority of dead cells, while no difference was observed in the conventional Delfia assay. Computed analysis of NK cell trajectories revealed distinct migratory behaviors, including trajectory length, diameter, average speed, and arrest coefficient. In 3D microfluidic experiments, NK cell attachment to pTNF-activated PAECs substantially increased, accompanied by more dead PAECs compared to control conditions. NK cell trajectories showed versatile migration in various directions and interactions with PAECs. This study uniquely demonstrates NK attachment and killing in a 3D system that mimics blood vessel conditions. Our microscope method offers sensitive single-cell level results, addressing diverse aspects of NK functions. It is adaptable for studying other immune and target cells, providing insights into various biological questions.

NK Cell and Monocyte Dysfunction in Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infection characterized by multiorgan involvement and inflammation. Testing of cellular function ex vivo to understand the aberrant immune response in MIS-C is limited. Despite strong Ab production in MIS-C, SARS-CoV-2 nucleic acid testing can remain positive for 4-6 wk postinfection. Therefore, we hypothesized that dysfunctional cell-mediated Ab responses downstream of Ab production may be responsible for delayed clearance of viral products in MIS-C. In MIS-C, monocytes were hyperfunctional for phagocytosis and cytokine production, whereas NK cells were hypofunctional for both killing and cytokine production. The decreased NK cell cytotoxicity correlated with an NK exhaustion marker signature and systemic IL-6 levels. Potentially providing a therapeutic option, cellular engagers of CD16 and SARS-CoV-2 proteins were found to rescue NK cell function invitro. Taken together, our results reveal dysregulation in Ab-mediated cellular responses of myeloid and NK cells that likely contribute to the immune pathology of this disease.

SMAD4 enhances the cytotoxic efficacy of human NK cells against colorectal cancer cells via the m6A reader YTHDF2.

Colorectal cancer (CRC) ranks as the third most prevalent malignant neoplasm in terms of both morbidity and mortality. Within the tumor microenvironment (TME) of CRC, the diminished presence and diminished cytotoxic function of natural killer (NK) cells serve as important factors driving the advancement of CRC; however, the precise regulatory mechanisms governing this phenomenon remain incompletely understood. Consequently, the identification of novel, potential anti-CRC targets associated with NK cells emerges as a pressing and paramount concern warranting immediate attention. We examined the regulatory mechanism of SMAD4-mediated NK cell cytotoxicity on CRC by utilizing various experimental techniques, such as qRT-PCR, flow cytometry. Our findings revealed that the expression of SMAD4 is decreased in NK cells within the TME of human CRC. Furthermore, we observed that enforced upregulation of SMAD4 resulted in enhanced cytotoxicity of NK cells towards CRC cells. Furthermore, our research has revealed that YTHDF2 functions as a downstream effector of SMAD4, playing a crucial role in the control of transcription and translation of m6A-modified RNA. Moreover, our investigation demonstrated that increased expression of SMAD4 promoted the activating receptor NKG2D by elevating levels of YTHDF2. Ultimately, the SMAD4-YTHDF2 regulatory axis significantly enhanced the cytotoxicity of NK cells against human CRC cells. Our study unveils a novel mechanism through which SMAD4 modulates the cytotoxicity of NK cells towards CRC cells, suggesting that SMAD4 may hold promise as a potential therapeutic target for NK cell therapy in CRC.

Dual-responsive natural killer cell nano-engagers for cancer immunotherapy via inhibiting IL-6/JAK2/STAT3 pathway

Natural killer (NK) cell-based immunotherapy is a promising approach for treating solid tumors and hematological malignancies. However, its therapeutic efficacy is limited by poor tumor infiltration and suppressive tumor microenvironment. Here, we introduce a rapid, simple, and efficient solution: bovine serum albumin-stabilized ultra-small (4 nm) NK cell nano-engagers, termed Bi2Se3@BSA nanodots (Nds). These Nds, responsive to high H2O2 levels in tumor cell environments, enhance near-infrared (NIR)-II photothermic immunotherapy. In vitro and in vivo experiments demonstrate their effectiveness in activating photothermal therapy (PTT)-induced immunogenic cell death (ICD), initiating immune cascade reactions, and stimulating immune response activation. By upregulating NKG2D, RAE-1, and secreting cytokines such as IFN-γ and TNF-α, targeted NK cell infiltration is achieved, reversing the immunosuppressive tumor microenvironment and optimizing NK cell cytotoxicity. Transcriptomic analysis confirms the association of immune response activation with the IL-6/JAK2/STAT3 signaling pathway. Notably, combining these nano-engagers with immune checkpoint inhibitors (aPD-1) significantly enhances therapeutic efficacy, facilitating tumor eradication and reducing recurrence risk. Taken together, NK cell nano-engagers inhibit the IL-6/JAK2/STAT3 signaling pathway, target NK cell activation, stimulate immune functions, and improve the immunosuppressive microenvironment. This study presents an alternative strategy for NK cell-based immunotherapy and highlights this promising tool for cancer immunotherapy.

INTASYL self-delivering RNAi decreases TIGIT expression, enhancing NK cell cytotoxicity: a potential application to increase the efficacy of NK adoptive cell therapy against cancer

Natural killer (NK) cells are frontline defenders against cancer and are capable of recognizing and eliminating tumor cells without prior sensitization or antigen presentation. Due to their unique HLA mismatch tolerance, they are ideal for adoptive cell therapy (ACT) because of their ability to minimize graft-versus-host-disease risk. The therapeutic efficacy of NK cells is limited in part by inhibitory immune checkpoint receptors, which are upregulated upon interaction with cancer cells and the tumor microenvironment. Overexpression of inhibitory receptors reduces NK cell-mediated cytotoxicity by impairing the ability of NK cells to secrete effector cytokines and cytotoxic granules. T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), a well-known checkpoint receptor involved in T-cell exhaustion, has recently been implicated in the exhaustion of NK cells. Overcoming TIGIT-mediated inhibition of NK cells may allow for a more potent antitumor response following ACT. Here, we describe a novel approach to TIGIT inhibition using self-delivering RNAi compounds (INTASYL™) that incorporates the features of RNAi and antisense technology. INTASYL compounds demonstrate potent activity and stability, are rapidly and efficiently taken up by cells, and can be easily incorporated into cell product manufacturing. INTASYL PH-804, which targets TIGIT, suppresses TIGIT mRNA and protein expression in NK cells, resulting in increased cytotoxic capacity and enhanced tumor cell killing in vitro. Delivering PH-804 to NK cells before ACT has emerged as a promising strategy to counter TIGIT inhibition, thereby improving the antitumor response. This approach offers the potential for more potent off-the-shelf products for adoptive cell therapy, particularly for hematological malignancies.

Optimizing the Procedure for Manufacturing Clinical-grade Genetically Manipulated NK cells for Adoptive Immunotherapy

BackgroundEx vivo expanded natural killer (NK) cells hold significant potential as antitumor effector cells for adoptive immunotherapy. However, producing clinical-grade genetically modified NK cells in sufficient quantities presents a considerable challenge. MethodsWe tested RPMI 1640, KBM581, SCGM, NK MACS, X-VIVO 15, and AIM-V, each supplemented with fetal bovine serum (FBS), human AB serum, human platelet lysate (HPL), or Immune Cell Serum Replacement (SR) combined with feeder cells, to produce cytotoxic NK cells. Subsequent analyses were conducted to assess cell viability, expansion folds, cytotoxicity, immunophenotype, and transcriptome profile of NK cells under certain conditions. Furthermore, transfer plasmids varying in transgene size, promoter elements, backbones and packaging plasmids with different envelopes were used to transduce NK cells and differences in transduction efficiency were compared. Nucleofection was performed every two days from Day 0 to Day 12 to determine the optimal time window for gene editing. ResultsNK cells cultured in KBM581 medium supplemented with SR exhibited the best expansion, achieving over 5000-fold increase within two weeks and exceeding 25,000-fold expansion within three weeks. Additionally, NK cells cultured in KBM581 medium with human AB serum demonstrated the highest cytolytic activities and exhibited higher expression of NKp30, 2B4, PRF1, Granzyme B, and IL2RG. Baboon envelope (BaEV) pseudotyped lentivirus outperformed BaEV-Vesicular Stomatitis Virus type-G (VSVG) hybrid envelope lentivirus, achieving robust NK cell transduction. Additionally, efficient gene knockout efficiency was achieved in NK cells on day 4 to day 6 post feeder cell activation using LONZA DN-100 program, which can strike a balance between editing efficiency and cell expansion. ConclusionsThis research presents a Good Manufacturing Practice (GMP)-compliant protocol utilizing a feeder cell expansion system for the large-scale production of highly cytotoxic Natural Killer (NK) cells. The protocol facilitates genetic modification of these cells, positioning them as promising candidates for universal therapeutic applications in immunotherapy.

CT45A1-mediated MLC2 (MYL9) phosphorylation promotes natural killer cell resistance and outer cell fate in a cell-in-cell structure, potentiating the progression of microsatellite instability-high colorectal cancer.

Patients with microsatellite instability-high (MSI-H) colorectal cancer (CRC) have high tumor mutation burden and tumor immunogenicity, exhibiting a higher response rate to immunotherapy and better survival. However, a portion of MSI-H CRC patients still experience adverse disease outcomes. We aimed to identify the tumor-autonomous regulators determining these heterogeneous clinical outcomes. The Cancer Genome Atlas (TCGA) dataset was used to identify regulators in MSI-H CRC patients with unfavorable outcomes. Stable CRC tumor clones expressing targeted regulators were established to evaluate migratory and stemness properties, immune cell vulnerability, and cell-in-cell (CIC) structure formation. RNA-sequencing (RNA-seq) was used to identify enriched biological pathways in stable CRC tumor clones. Clinicopathological characterization of formalin-fixed paraffin-embedded (FFPE) MSI-H CRC specimens was performed to explore the underlying mechanisms involved. We showed that cancer/testis antigen family 45 member A1 (CT45A1) expression was upregulated in MSI-H CRC patients with poor survival outcomes. CT45A1-expressing microsatellite stable (MSS) CRC cells showed enhanced migratory ability. However, CT45A1-expressing MSI-H CRC cells, but not MSS CRC cells, showed higher resistance to natural killer (NK) cell cytotoxicity and served as outer cells in homotypic CIC structures, preventing exogenous or therapeutic antibody access to inner CRCcells. Inactivating RHO-ROCK/MLCK-MLC2 signaling with small-molecule inhibitors or short-hairpin RNAs (shRNAs) targeting myosin light chain kinase (MYLK) abolished NK cell resistance and reduced the outer cell fate of CT45A1-expressing MSI-H CRC cells. In MSI-H CRC patients, CT45A1-positive tumors exhibited increased MLC2 phosphorylation, increased outer cell fate, and decreased survival. We demonstrated that CT45A1 potentiates the advanced progression of MSI-H CRC, and targeting MLC2 phosphorylation may enhance immunotherapy efficacy in CT45A1-positive MSI-H CRC patients.

Clinical and morphological specifics, pathogenetic ways of skin manifestations in SARS-CoV-2 infection

To date, the most studied clinical and morphological changes characteristic of SARS-CoV-2 virus are its pulmonary manifestations and cardiovascular involvement. However, the evaluation of COVID-associated skin changes and the analysis of their mechanisms are also important for us, because the skin manifestations of the infection can change the patient's appearance for the worse, i.e. affect the aesthetic sphere and significantly reduce the quality of life. The study of not only skin manifestations of COVID-19, but also their morphological substrate and pathogenetic basis allows us to apply the most effective methods of treatment and provide adequate management of patients even in the post-coital status. According to the information collected to date, the most frequently reported skin manifestations of SARS-CoV-2 are pseudo-frostbite, maculopapular and vesicular lesions, urticaria, lividoid and necrotic lesions, hemorrhagic purpura (vasculitis), and conditions from the group of other unclassified skin lesions. Despite the variety of clinical variants of SARS-CoV-2-associated skin changes, morphological stigmas are often stencil-like: these are areas of lymphohistiocytic infiltration of perivascular localization, the presence of fibrinoid necrosis foci in the vessel walls, the formation of occlusive thrombi, erythrocyte extravasation. Mechanisms of damage to epidermis and dermis within COVID-19 infection may be due to the influence of complement components, activation of cytotoxic lymphocytes and NK-cells, excessive synthesis of proinflammatory cytokines, in particular, interleukin 6, as well as interferons, hyperergic reactions. In addition to routine morphological, immunohistochemical examination of skin biopsy specimens from patients with different forms of skin manifestations of SARS-CoV-2 infection is an important tool in the diagnostic confirmation of COVID-associated dermatologic pathology, especially in patients with a suspected history of this disease or with problematic laboratory results.