Genetic ablation of adhesion ligands mitigates rejection of allogeneic cellular immunotherapies.

Allogeneic cellular immunotherapies hold promise for broad clinical implementation but face limitations due to potential rejection of donor cells by the host immune system. Silencing of beta-2 microglobulin (B2M) expression is commonly employed to evade T cell-mediated rejection by the host, although the absence of B2M is expected to trigger missing-self responses by host natural killer (NK) cells. Here, we demonstrate that genetic deletion of the adhesion ligands CD54 and CD58 in B2M-deficient chimeric antigen receptor (CAR) T cells and multi-edited induced pluripotent stem cell (iPSC)-derived CAR NK cells reduces their susceptibility to rejection by host NK cells in vitro and in vivo. The absence of adhesion ligands limits rejection in a unidirectional manner in B2M-deficient and B2M-sufficient settings without affecting the antitumor functionality of the engineered donor cells. Thus, these data suggest that genetic ablation of adhesion ligands effectively alleviates rejection by host immune cells, facilitating the implementation of universal immunotherapy.

The Immunotherapy of Acute Myeloid Leukemia: A Clinical Point of View.

The potential of the immune system to eradicate leukemic cells has been consistently demonstrated by the Graft vs. Leukemia effect occurring after allo-HSCT and in the context of donor leukocyte infusions. Various immunotherapeutic approaches, ranging from the use of antibodies, antibody-drug conjugates, bispecific T-cell engagers, chimeric antigen receptor (CAR) T-cells, and therapeutic infusions of NK cells, are thus currently being tested with promising, yet conflicting, results. This review will concentrate on various types of immunotherapies in preclinical and clinical development, from the point of view of a clinical hematologist. The most promising therapies for clinical translation are the use of bispecific T-cell engagers and CAR-T cells aimed at lineage-restricted antigens, where overall responses (ORR) ranging from 20 to 40% can be achieved in a small series of heavily pretreated patients affected by refractory or relapsing leukemia. Toxicity consists mainly in the occurrence of cytokine-release syndrome, which is mostly manageable with step-up dosing, the early use of cytokine-blocking agents and corticosteroids, and myelosuppression. Various cytokine-enhanced natural killer products are also being tested, mainly as allogeneic off-the-shelf therapies, with a good tolerability profile and promising results (ORR: 20-37.5% in small trials). The in vivo activation of T lymphocytes and NK cells via the inhibition of their immune checkpoints also yielded interesting, yet limited, results (ORR: 33-59%) but with an increased risk of severe Graft vs. Host disease in transplanted patients. Therefore, there are still several hurdles to overcome before the widespread clinical use of these novel compounds.

Define Critical Parameters of Trastuzumab-Mediated ADCC Assays via Assay Optimization Processes, Focusing on the Impact of Cryopreserved Effector Cells on Assay Performance.

The mechanisms of mAb-induced ADCC have been well established. However, the ADCC bioassays used to quantify mAb-induced ADCC require continued development/refinement to properly assess and compare the potency of newly developed therapeutic mAbs and biosimilars to meet regulatory requirements. We used trastuzumab and a lactate dehydrogenase (LDH)-based ADCC bioassay as a model to define critical parameters of the ADCC bioassay, describing how several bioassay parameters, including preparation of effector cells, E/T ratio, target cell selection, bioassay media components, and treatment time can influence the data quality of the ADCC activity. We confirm that a 4 to 24 h recovery cultivation is required to restore peripheral blood mononuclear cells (PBMCs) and natural killer (NK) cell activity toward ADCC when using cryopreserved PBMCs. Furthermore, we delineated the cellular mechanisms underlying the restored ADCC activity following the recovery cultivation. We observed that CD69, an early marker of NK cell activation, was upregulated and a new subset CD56dim/CD16dim population was dramatically increased in the recovered NK cells, which led to an increase in expression and secretion of perforin, granzyme B, and cytokine production. This study provides comprehensive technical insights into ADCC bioassay optimization to inform trastuzumab biosimilar development. The knowledge gained from this study can also be leveraged to guide bioassay development for therapeutic mAbs with ADCC as the primary mechanism of action.

Recurrent Treatment of Refractory Acute Cellular Rejection with Alemtuzumab after Lung Transplantation.

We present an exceptional case of a lung transplant recipient successfully treated by multiple courses of alemtuzumab for refractory acute cellular rejection. The patient experienced multiple episodes of acute cellular rejection following the transplantation procedure. Alemtuzumab was initiated as third-line rejection treatment and was repeated six times. Each treatment course resulted in complete recovery of the pulmonary function and depletion of T- and B-lymphocytes and NK cells. The onset of rejection was consistently preceded by the recovery of NK cells, while T- and B-lymphocytes remained depleted. This suggests a rejection process mediated by NK cells. This case contributes to recent research findings suggesting that NK cells play a significant role in acute cellular rejection in lung transplant recipients and stresses the importance to further investigate the role of NK cells in rejection. Furthermore, it demonstrates that acute cellular rejection following lung transplantation can be repeatedly managed by treatment with alemtuzumab. DATA AVAILABILITY STATEMENT: The authors confirm that the data supporting the findings of this study are available within the article.

Disruption of TGF-ß signaling pathway is required to mediate effective killing of hepatocellular carcinoma by human iPSC-derived NK cells.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Transforming growth factor beta (TGF-ß) is highly expressed in the liver tumor microenvironment and is known to inhibit immune cell activity. Here, we used human induced pluripotent stem cells (iPSCs) to produce natural killer (NK) cells engineered to mediate improved anti-HCC activity. Specifically, we produced iPSC-NK cells with either knockout TGF-ß receptor 2 (TGFBR2-KO) or expression of a dominant negative (DN) form of the TGF-ß receptor 2 (TGFBR2-DN) combined with chimeric antigen receptors (CARs) that target either GPC3 or AFP. The TGFBR2-KO and TGFBR2-DN iPSC-NK cells are resistant to TGF-ß inhibition and improved anti-HCC activity. However, expression of anti-HCC CARs on iPSC-NK cells did not lead to effective anti-HCC activity unless there was also inhibition of TGF-ß activity. Our findings demonstrate that TGF-ß signaling blockade is required for effective NK cell function against HCC and potentially other malignancies that express high levels of TGF-ß.

An extended flow cytometry evaluation of ex vivo expanded NK cells using K562.Clone1, a feeder cell line manufactured in Brazil.

BACKGROUND: Natural Killer (NK) cells play a crucial role in the immune system's response against cancer. However, the challenge of obtaining the required quantity of NK cells for effective therapeutic response necessitates the development of strategies for their ex vivo expansion. OBJECTIVE: This study aimed to develop a novel feeder cell line, K562.Clone1, capable of promoting the ex vivo expansion of NK cells while preserving their cytotoxic potential. STUDY DESIGN: The K562 leukemic cell line was transduced with mbIL-21 and 4-1BBL proteins to generate K562.Clone1 cells. NK cells were then co-cultured with these feeder cells, and their expansion rate was monitored over 14 days. The cytotoxic potential of the expanded NK cells was evaluated against acute myeloid leukemia blasts and tumor cell lines of leukemia and glial origin. Statistical analysis was performed to determine the significance of the results. RESULTS: The K562.Clone1 co-cultured with peripheral NK showed a significant increase in cell count, with an approximately 94-fold expansion over 14 days. Expanded NK cells demonstrated cytotoxicity against the tested tumor cell lines, indicating the preservation of their cytotoxic characteristics. Additionally, the CD56, CD16, inhibitory KIRs, and activation receptors were conserved and present in a well-balanced manner. CONCLUSION: The study successfully developed a feeder cell line, K562.Clone1, that effectively promotes the expansion of NK cells ex vivo while maintaining their cytotoxic potential. This development could significantly contribute to the advancement of NK cell therapy, especially in Brazil.

Innate and adaptive effector immune drivers of cytomegalovirus disease in lung transplantation: a double-edged sword.

Up to 90% of the global population has been infected with cytomegalovirus (CMV), a herpesvirus that remains latent for the lifetime of the host and drives immune dysregulation. CMV is a critical risk factor for poor outcomes after solid organ transplant, though lung transplant recipients (LTR) carry the highest risk of CMV infection, and CMV-associated comorbidities compared to recipients of other solid organ transplants. Despite potent antivirals, CMV remains a significant driver of chronic lung allograft dysfunction (CLAD), re-transplantation, and death. Moreover, the extended utilization of CMV antiviral prophylaxis is not without adverse effects, often necessitating treatment discontinuation. Thus, there is a critical need to understand the immune response to CMV after lung transplantation. This review identifies key elements of each arm of the CMV immune response and highlights implications for lung allograft tolerance and injury. Specific attention is paid to cellular subsets of adaptive and innate immune cells that are important in the lung during CMV infection and reactivation. The concept of heterologous immune responses is reviewed in depth, including how they form and how they may drive tissue- and allograft-specific immunity. Other important objectives of this review are to detail the emerging role of NK cells in CMV-related outcomes, in addition to discussing perturbations in CMV immune function stemming from pre-existing lung disease. Finally, this review identifies potential mechanisms whereby CMV-directed treatments may alter the cellular immune response within the allograft.

Suppressing PD-L1 Expression via AURKA Kinase Inhibition Enhances Natural Killer Cell-Mediated Cytotoxicity against Glioblastoma.

Immunotherapies have shown significant promise as an impactful strategy in cancer treatment. However, in glioblastoma multiforme (GBM), the most prevalent primary brain tumor in adults, these therapies have demonstrated lower efficacy than initially anticipated. Consequently, there is an urgent need for strategies to enhance the effectiveness of immune treatments. AURKA has been identified as a potential drug target for GBM treatment. An analysis of the GBM cell transcriptome following AURKA inhibition revealed a potential influence on the immune system. Our research revealed that AURKA influenced PD-L1 levels in various GBM model systems in vitro and in vivo. Disrupting AURKA function genetically led to reduced PD-L1 levels and increased MHC-I expression in both established and patient-derived xenograft GBM cultures. This process involved both transcriptional and non-transcriptional pathways, partly implicating GSK3ß. Interfering with AURKA also enhanced NK-cell-mediated elimination of GBM by reducing PD-L1 expression, as evidenced in rescue experiments. Furthermore, using a mouse model that mimics GBM with patient-derived cells demonstrated that Alisertib decreased PD-L1 expression in living organisms. Combination therapy involving anti-PD-1 treatment and Alisertib significantly prolonged overall survival compared to vehicle treatment. These findings suggest that targeting AURKA could have therapeutic implications for modulating the immune environment within GBM cells.

Oncolytic vaccinia virus harboring CLEC2A gene enhances viral replication and antitumor efficacy.

In the field of innovative cancer treatment strategies, oncolytic vaccinia virus (VV)es have gained traction as promising vectors. In the current study, we inserted the human C-type lectin domain family 2 member A (CLEC2A) gene into VV, creating a replicating therapeutic, oncoVV-CLEC2A. The findings reveal that oncoVV-CLEC2A effectively suppresses colorectal proliferation of mouse xenografts and a range of human cancer cell lines by augmenting viral reproduction capabilities, including the lung cancer H460 cell line, colorectal cancer cell lines (HCT116 and SW620), and hepatocellular carcinoma HuH-7 cell line. Moreover, it is evident that oncoVV-CLEC2A can induce antitumor immunity by boosting cytokine production but not antivirus response, and enhancing calreticulin expression. Further investigation indicates that oncoVV-CLEC2A can enhance antitumor capabilities by activating natural killer cells to produce interferon-γ and induce M1-like macrophage polarization. These findings shed light on the antitumor mechanisms of oncoVV-CLEC2A, provide a theoretical basis for oncolytic therapies, and lay the groundwork for novel strategies for modifying VVs.

Advances in CAR-NK cell therapy for hematological malignancies.

Chimeric antigen receptor T (CAR-T) cell therapy has revolutionized the treatment of hematological malignancies, demonstrably improving patient outcomes and prognosis. However, its application has introduced new challenges, such as safety concerns, off-target toxicities, and significant costs. Natural killer (NK) cells are crucial components of the innate immune system, capable of eliminating tumor cells without prior exposure to specific antigens or pre-activation. This inherent advantage complements the limitations of T cells, making CAR-NK cell therapy a promising avenue for hematological tumor immunotherapy. In recent years, preclinical and clinical studies have yielded preliminary evidence supporting the safety and efficacy of CAR-NK cell therapy in hematological malignancies, paving the way for future advancements in immunotherapy. This review aims to succinctly discuss the characteristics, significant therapeutic progress, and potential challenges associated with CAR-NK cell therapy.

A "Prime and Expand" strategy using the multifunctional fusion proteins to generate memory-like NK cells for cell therapy.

Adoptive cellular therapy (ACT) using memory-like (ML) natural killer (NK) cells, generated through overnight ex vivo activation with IL-12, IL-15, and IL-18, has shown promise for treating hematologic malignancies. We recently reported that a multifunctional fusion molecule, HCW9201, comprising IL-12, IL-15, and IL-18 domains could replace individual cytokines for priming human ML NK cell programming ("Prime" step). However, this approach does not include ex vivo expansion, thereby limiting the ability to test different doses and schedules. Here, we report the design and generation of a multifunctional fusion molecule, HCW9206, consisting of human IL-7, IL-15, and IL-21 cytokines. We observed > 300-fold expansion for HCW9201-primed human NK cells cultured for 14 days with HCW9206 and HCW9101, an IgG1 antibody, recognizing the scaffold domain of HCW9206 ("Expand" step). This expansion was dependent on both HCW9206 cytokines and interactions of the IgG1 mAb with CD16 receptors on NK cells. The resulting "Prime and Expand" ML NK cells exhibited elevated metabolic capacity, stable epigenetic IFNG promoter demethylation, enhanced antitumor activity in vitro and in vivo, and superior persistence in NSG mice. Thus, the "Prime and Expand" strategy represents a simple feeder cell-free approach to streamline manufacturing of clinical-grade ML NK cells to support multidose and off-the-shelf ACT.

Peripheral PD-1+NK cells could predict the 28-day mortality in sepsis patients.

Background: Unbalanced inflammatory response is a critical feature of sepsis, a life-threatening condition with significant global health burdens. Immune dysfunction, particularly that involving different immune cells in peripheral blood, plays a crucial pathophysiological role and shows early warning signs in sepsis. The objective is to explore the relationship between sepsis and immune subpopulations in peripheral blood, and to identify patients with a higher risk of 28-day mortality based on immunological subtypes with machine-learning (ML) model. Methods: Patients were enrolled according to the sepsis-3 criteria in this retrospective observational study, along with age- and sex-matched healthy controls (HCs). Data on clinical characteristics, laboratory tests, and lymphocyte immunophenotyping were collected. XGBoost and k-means clustering as ML approaches, were employed to analyze the immune profiles and stratify septic patients based on their immunological subtypes. Cox regression survival analysis was used to identify potential biomarkers and to assess their association with 28-day mortality. The accuracy of biomarkers for mortality was determined by the area under the receiver operating characteristic (ROC) curve (AUC) analysis. Results: The study enrolled 100 septic patients and 89 HCs, revealing distinct lymphocyte profiles between the two groups. The XGBoost model discriminated sepsis from HCs with an area under the receiver operating characteristic curve of 1.0 and 0.99 in the training and testing set, respectively. Within the model, the top three highest important contributions were the percentage of CD38+CD8+T cells, PD-1+NK cells, HLA-DR+CD8+T cells. Two clusters of peripheral immunophenotyping of septic patients by k-means clustering were conducted. Cluster 1 featured higher proportions of PD1+ NK cells, while cluster 2 featured higher proportions of naïve CD4+T cells. Furthermore, the level of PD-1+NK cells was significantly higher in the non-survivors than the survivors (15.1% vs 8.6%, P<0.01). Moreover, the levels of PD1+ NK cells combined with SOFA score showed good performance in predicting the 28-day mortality in sepsis (AUC=0.91,95%CI 0.82-0.99), which is superior to PD1+ NK cells only(AUC=0.69, sensitivity 0.74, specificity 0.64, cut-off value of 11.25%). In the multivariate Cox regression, high expression of PD1+ NK cells proportion was related to 28-day mortality (aHR=1.34, 95%CI 1.19 to 1.50; P<0.001). Conclusion: The study provides novel insights into the association between PD1+NK cell profiles and prognosis of sepsis. Peripheral immunophenotyping could potentially stratify the septic patients and identify those with a high risk of 28-day mortality.

LINC00665 promotes the progression and immune evasion of lung cancer by facilitating the translation of TCF7 protein through dependence on IRES.

OBJECTIVE: To investigate the influence of LINC00665 on the development and immune evasion of lung cancer. METHODS: Tumor tissues and corresponding adjacent tissues were collected from 84 lung cancer patients, categorized into non-metastatic (n = 58) and metastatic (n = 26) groups. LINC00665 expression in lung cancer and metastatic lung cancer tissues was assessed via qRT-PCR. Pearson correlation analysis was conducted to examine the correlation between LINC00665 and immune-modulating cytokines (TGF-ß, IL-10, IL-1ß, IFN-γ, IL-2, TNF-α). A549 and H1299 cells, with relatively high LINC00665 expression, were used for in vitro studies. Cells were transfected with LINC00665-targeting shRNA, and changes in proliferation, apoptosis, migration, invasion, and NK cell cytotoxicity were assessed. Downstream molecular mechanisms of LINC00665 were investigated using GEO database analysis, highlighting the association with HHLA2. LINC00665's role in promoting HHLA2 expression via binding with TCF7 was explored. In low LINC00665-expressing A549/H1299 cells, overexpression of HHLA2 was performed to evaluate effects on malignant behavior and NK cell sensitivity. A xenograft model was established for in vivo validation through tumor volume and weight measurements, Ki-67 immunoreactivity analysis, and flow cytometry analysis of CD107a + NK cells. RESULTS: LINC00665, TCF7 mRNA, and HHLA2 mRNA expression levels were significantly higher in lung cancer tissues than adjacent tissues, with non-metastatic lung cancer showing higher expression than metastatic lung cancer. In metastatic lung cancer, LINC00665 positively correlated with immune-suppressive cytokines (TGF-ß, IL-10, IL-1ß) and negatively correlated with anti-tumor cytokines (IFN-γ, IL-2, TNF-α). LINC00665 knockdown significantly inhibited lung cancer cell growth and metastasis, promoting sensitivity to NK cells. Further analysis revealed that LINC00665 recruits transcription factor TCF7 to upregulate HHLA2 expression in lung cancer cells, thereby facilitating lung cancer development and immune escape. CONCLUSION: LINC00665, through recruitment of TCF7 and upregulation of HHLA2, inhibits NK cell cytotoxicity, promoting the development and immune evasion of lung cancer.

Natural killer cell memory: challenges and opportunities for cancer immunotherapy.

Substantial advancements have been made in recent years in comprehending immune memory, which enhances the secondary response through prior infections. The ability of vertebrate T and B lymphocytes to exhibit classic recall responses has long been regarded as a distinguishing characteristic. However, natural killer (NK) cells have been found to acquire immunological memory in a manner akin to T and B cells. The fundamental principles derived from the investigation of NK cell memory offer novel insights into innate immunity and have the potential to pave the way for innovative strategies to enhance therapeutic interventions against multiple diseases including cancer. Here, we reviewed the fundamental characteristics, memory development and regulatory mechanism of NK cell memory. Moreover, we will conduct a comprehensive evaluation of the accomplishments, obstacles, and future direction pertaining to the utilization of NK cell memory in the field of cancer immunotherapy.

Chrysin Enhances Anti-cancer Activity of Jurkat T Cell and NK-92 Cells Against Human Breast Cancer Cell Lines.

Chrysin, a naturally occurring flavonoid in plant and bee products, demonstrates notable biological activities, including anti-cancer effects. These properties are partially attributed to its capability to activate immune cells. This study focused on exploring the immunomodulatory potential of chrysin on NK-92 and Jurkat-T cells targeting breast cancer cells (BCC). Chrysin leads to activation of NK-92 and T cells facilitated by the addition of human recombinant IL-2 and PHA-M. The anti-cancer efficacy of chrysin on these immune cells was evaluated in a co-culture setup with EGF-stimulated MCF-7 and MDA-MB-231 cells. Findings revealed that chrysin notably increased the cytotoxicity of NK-92 and T cells towards MCF-7 and MDA-MB-231 cells, with the most significant impact observed on MCF-7 cells (20%). The activation of NK-92 cells, marked by increased IFN-γ production and CD56 expression, correlated with enhanced secretion of cytokines. Additionally, the activation of these cells against BCC was linked with elevated levels of granzyme-B, TNF-α, and nitric oxide (NO). Similarly, the cytotoxic activation of Jurkat-T cells against BCC was characterized by increased production of granzyme-B, IL-2, and IFN-γ. Consequently, these results support the hypothesis that chrysin significantly contributes to the activation and functional enhancement of NK-92 and T-cells against two distinct BCC lines.

Seasonal variation in BCG-induced trained immunity.

The Bacille Calmette-Guerin (BCG) vaccine is a well-established inducer of innate immune memory (also termed trained immunity), causing increased cytokine production upon heterologous secondary stimulation. Innate immune responses are known to be influenced by season, but whether seasons impact induction of trained immunity is not known. To explore the influence of season on innate immune memory induced by the BCG vaccine, we vaccinated healthy volunteers with BCG either during winter or spring. Three months later, we measured the ex vivo cytokine responses against heterologous stimuli, analyzed gene expressions and epigenetic signatures of the immune cells, and compared these with the baseline before vaccination. BCG vaccination during winter induced a stronger increase in the production of pro-inflammatory cytokines by peripheral blood mononuclear cells (PBMCs) upon stimulation with different bacterial and fungal stimuli, compared to BCG vaccination in spring. In contrast, winter BCG vaccination resulted in lower IFNγ release in PBMCs compared to spring BCG vaccination. Furthermore, NK cells of the winter-vaccinated people had a greater pro-inflammatory cytokine and IFNγ production capacity upon heterologous stimulation. BCG had only minor effects on the transcriptome of monocytes 3 months later. In contrast, we identified season-dependent epigenetic changes in monocytes and NK cells induced by vaccination, partly explaining the higher immune cell reactivity in the winter BCG vaccination group. These results suggest that BCG vaccination during winter is more prone to induce a robust trained immunity response by activating and reprogramming the immune cells, especially NK cells. (Dutch clinical trial registry no. NL58219.091.16).

Boosting the anti-tumor activity of natural killer cells by caripe 8 - A Carapichea ipecacuanha isolated cyclotide.

Cyclotides are head-to-tail cyclized peptides with a unique cystine-knot motif. Their structure provides exceptional resistance against enzymatic, chemical, or thermal degradation compared to other peptides. Peptide-based therapeutics promise high specificity, selectivity and lower immunogenicity, making them safer alternatives to small molecules or large biologicals. Cyclotides were researched due to their anti-cancer properties by inducing apoptosis in tumor cells in the past, but the impact of cyclotides on cytotoxic immune cells was poorly studied. Natural Killer (NK) cells are cytotoxic innate lymphoid cells and play an important role in the defense against infected, stressed and transformed cells. NK cells do not need prior sensitization and act in an antigen independent manner, holding promising potential in the field of immunotherapy. To investigate the effect of immunomodulatory cyclotides on NK cells, we evaluated several peptide-enriched plant extracts on NK cell mediated cytotoxicity. We observed that the extract samples derived from Carapichea ipecacuanha (Brot.) L. Andersson augments the killing potential of mouse NK cells against different tumor targets in vitro. Subsequent isolation of cyclotides from C. ipecacuanha extracts led to the identification of a primary candidate that enhances cytotoxicity of both mouse and human NK cells. The augmented killing is facilitated by the increased degranulation capacity of NK cells. In addition, we noted a direct toxic effect of caripe 8 on tumor cells, suggesting a dual therapeutic potential in cancer treatment. This study offers novel insights how natural peptides can influence NK cell cytotoxicity. These pre-clinical findings hold significant promise for advancing current immunotherapeutic approaches.

Emerging role of C5aR2: novel insights into the regulation of uterine immune cells during pregnancy.

Pregnancy is a fascinating immunological phenomenon because it allows allogeneic fetal and placental tissues to survive inside the mother. As a component of innate immunity with high inflammatory potential, the complement system must be tightly regulated during pregnancy. Dysregulation of the complement system plays a role in pregnancy complications including pre-eclampsia and intrauterine growth restriction. Complement components are also used as biomarkers for pregnancy complications. However, the mechanisms of detrimental role of complement in pregnancy is poorly understood. C5a is the most potent anaphylatoxin and generates multiple immune reactions via two transmembrane receptors, C5aR1 and C5aR2. C5aR1 is pro-inflammatory, but the role of C5aR2 remains largely elusive. Interestingly, murine NK cells have been shown to express C5aR2 without the usual co-expression of C5aR1. Furthermore, C5aR2 appears to regulate IFN-γ production by NK cells in vitro. As IFN-γ produced by uterine NK cells is one of the major factors for the successful development of a vital pregnancy, we investigated the role anaphylatoxin C5a and its receptors in the establishment of pregnancy and the regulation of uterine NK cells by examinations of murine C5ar2-/- pregnancies and human placental samples. C5ar2-/- mice have significantly reduced numbers of implantation sites and a maternal C5aR2 deficiency results in increased IL-12, IL-18 and IFN-γ mRNA expression as well as reduced uNK cell infiltration at the maternal-fetal interface. Human decidual leukocytes have similar C5a receptor expression patterns showing clinical relevance. In conclusion, this study identifies C5aR2 as a key contributor to dNK infiltration and pregnancy success.

CXCR4 has a dual role in improving the efficacy of BCMA-redirected CAR-NK cells in multiple myeloma.

Multiple myeloma (MM) is a plasma cell disease with a preferential bone marrow (BM) tropism. Enforced expression of tissue-specific chemokine receptors has been shown to successfully guide adoptively-transferred CAR NK cells towards the malignant milieu in solid cancers, but also to BM-resident AML and MM. For redirection towards BM-associated chemokine CXCL12, we armored BCMA CAR-NK-92 as well as primary NK cells with ectopic expression of either wildtype CXCR4 or a gain-of-function mutant CXCR4R334X. Our data showed that BCMA CAR-NK-92 and -primary NK cells equipped with CXCR4 gained an improved ability to migrate towards CXCL12 in vitro. Beyond its classical role coordinating chemotaxis, CXCR4 has been shown to participate in T cell co-stimulation, which prompted us to examine the functionality of CXCR4-cotransduced BCMA-CAR NK cells. Ectopic CXCR4 expression enhanced the cytotoxic capacity of BCMA CAR-NK cells, as evidenced by the ability to eliminate BCMA-expressing target cell lines and primary MM cells in vitro and through accelerated cytolytic granule release. We show that CXCR4 co-modification prolonged BCMA CAR surface deposition, augmented ZAP-70 recruitment following CAR-engagement, and accelerated distal signal transduction kinetics. BCMA CAR sensitivity towards antigen was enhanced by virtue of an enhanced ZAP-70 recruitment to the immunological synapse, revealing an increased propensity of CARs to become triggered upon CXCR4 overexpression. Unexpectedly, co-stimulation via CXCR4 occurred in the absence of CXCL12 ligand-stimulation. Collectively, our findings imply that co-modification of CAR-NK cells with tissue-relevant chemokine receptors affect adoptive NK cell therapy beyond improved trafficking and retention within tumor sites.