Effector Lymphocytes Research Articles

Interleukin-12 decorated nanosized semiflexible Immunofilaments enable directed targeting and augmented IFNγ responses of Natural Killer Cells

Immunotherapies are a powerful strategy to treat cancer by modulating the immune system to raise an anti-tumor immune response. A prime example of immunotherapies are cytokines - small immunomodulatory molecules that are widely used to stimulate immune cells. Undirected administration of cytokines, however, can cause severe side effects, preventing the use of potent cytokines, such as Interleukin (IL)-12, which induces IFNγ responses by cytotoxic effector lymphocytes, including NK cells. Biomaterials, like nanoparticles, can encapsulate IL-12 and accumulate at the tumor site to alleviate side effects. Yet, the released IL-12 might not be directly targeted to extracellular IL-12 receptors on the specific effector cells, thereby potentially compromising the cytokine's therapeutic efficacy. Here, we develop a polymer-based platform to target NK cells, which we call immunofilaments. Immunofilaments are nanosized linear polymers that present an anti-CD16 antibody and IL-12 effectively to NK cells and lead to synergistic NK cell activation as highlighted by an increase in TNFα and IFNγ production and upregulation of multiple activation markers, including CD25, CD69, and degranulation marker CD107a. NK cell proliferation is enhanced in the presence of both anti-CD16 antibody and IL-12 compared to giving IL-12 separately. Finally, we demonstrate that the IF platform is suitable for in vivo applications, as immunofilaments readily activate human NK cells upon administration to mice. STATEMENT OF SIGNIFICANCE: IL-12 is a potent cytokine that stimulates IFNγ responses in NK cells, which supports an anti-tumor immune response. Due to its high potency, the delivery of IL-12 needs to be highly controlled to prevent severe adverse side effects, which can be achieved by using biomaterials. This study shows that nanosized polymers termed Immunofilaments can be used to immobilize IL-12 and effectively target and activate NK cells by co-conjugation of anti-CD16 antibodies. This work is a prime example of careful engineering of innovative biomaterials to improve immunotherapy.

Effect of methimazole treatment on Th1, Th17, and Th22 lymphocytes in pediatric Graves' disease patients.

Graves' disease is the leading cause of autoimmune hyperthyroidism. Thyroid hormones are an essential element of the endocrine system, playing a pivotal role in the body's development, especially important in children with intensified growth. Disturbance within thyroid tissue certainly affected the whole body. Nowadays, numerous research studies indicate different factors contributing to the onset of the disease; however, the exact pathomechanism of Graves' disease is still not fully understood, especially in the context of immune-related processes. Th1, Th17, and Th22 effector lymphocytes were found to be crucial participants in the disease outcome, as well as in autoimmune diseases. Here, our study aimed at assessing selected effector T lymphocytes, Th1, Th17, and Th22, in newly diagnosed pediatric Graves' disease patients, together with their association with thyroid-related parameters and the potential outcome of disease management. We indicated significant increases in the frequencies and absolute numbers of selected effector lymphocytes in Graves' disease patients. In addition, their mutual ratios, as well as Th1/Th17, Th/Th22, and Th17/Th22, seem to be significant in those diseases. Notably, low Th17/Th22 ratio values were distinguished as potential prognostic factors for normalizing TSH levels in response to methimazole treatment. To sum up, our research determines the crucial contribution of Th1, Th17, and Th22 cells in the pathogenesis of Graves' disease. Moreover, the mentioned subset of T cells is highly likely to play a substantial role in the potential prediction of therapy outcomes.

Mechanism of Shashen-Maidong herb pair in treating hepatocellular carcinoma using network pharmacology and experimental validation

Ethnopharmacological relevanceHepatocellular carcinoma (HCC) is among the most prevalent malignant tumors globally and represents a significant public health issue worldwide. Immune cell dysfunction is the crucial factor for the formation of immunosuppression microenvironment of HCC. Glehnia littoralis (A.Gray) F.Schmidt ex Miq. (Shashen) and Ophiopogon japonicus (Thunb.) Ker Gawl. (Maidong) are classic herb pair in traditional Chinese medicine (TCM) of nourishing Yin, and is widely applied in the treatment of HCC and possesses multiple immunomodulatory functions. However, the role of the the Shashen-Maidong herb pair (SS-MD) for the management of HCC and the potential mechanisms has not been explicated. Aim of the studyThe purpose of the research is to investigate the potential mechanism of the SS-MD herb pair for the management of HCC. Materials and methodsThe known components of the SS-MD herb pair were preliminarily identified using UPLC-Q-Orbitrap-MS/MS. The active ingredients of SS-MD herb pair in treating HCC were screened by constructing herb-component-target network, and the key therapeutic targets were explored by constructing a protein-protein interaction (PPI) network. The binding affinity of the key targets and components were validated through molecular docking and molecular dynamics simulations. GO biological function and KEGG pathway analyses were operated to elucidate the potential mechanisms of the SS-MD herb pair for the management of HCC. And the mechanism was verified in the tumor bearing mice model and cell co-culture experiments. ResultsNetwork pharmacology prediction revealed 39 active components and 138 targets of the SS-MD herb pair for the treatment of HCC. KEGG analysis mainly focused on Notch signaling pathway and Apoptosis signaling pathway. The targets were enriched in biological functions of lymphocyte effector function and lymphocyte apoptosis. In vivo and in vitro experiments proved that the SS-MD herb pair can improve the proportion of CD8+T cells in the HCC immune microenvironment, regulate its subgroup distribution. SS-MD herb pair promoted CD8+T cells to secrete IL-2, TNF-α, IFN-γ, Granzyme B and Perforin, and inhibited apoptosis by regulating Notch signaling pathway. ConclusionsThis study identified the key components, targets, and signaling pathways of the SS-MD herb pair, confirm that SS-MD herb pair play an immunomodulatory role in treating HCC, provides theoretical support for the collaborative treatment of HCC with TCM.

Trabectedin promotes oncolytic virus antitumor efficacy, viral gene expression, and immune effector function in models of bone sarcoma

We previously reported that the DNA alkylator and transcriptional-blocking chemotherapeutic agent trabectedin enhances oncolytic herpes simplex viroimmunotherapy in human sarcoma xenograft models, though the mechanism remained to be elucidated. Here we report trabectedin disrupts the intrinsic cellular anti-viral response which increases viral transcript presence in the human tumor cells. We also extended our synergy findings to syngeneic murine sarcoma models, which are poorly susceptible to virus infection. In the absence of robust virus replication, we found trabectedin enhanced viroimmunotherapy efficacy by reducing infiltrating immunosuppressive CD4 T and myeloid cells and stimulating granzyme expression in infiltrating T and NK cells to cause immune-mediated tumor regressions. Thus, trabectedin enhances both the direct virus-mediated killing of tumor cells and the viral-induced activation of cytotoxic effector lymphocytes to cause tumor regressions across models. Our data provide a strong rationale for clinical translation as both mechanisms should be simultaneously active in human patients.

On-Demand Elongation of Peptide Nanofibrils at Cellular Interfaces to Modulate Cell-Cell Interactions.

Natural cells can achieve specific cell-cell interactions by enriching nonspecific binding molecules on demand at intercellular contact faces, a pathway currently beyond synthetic capabilities. We are inspired to construct responsive peptide fibrils on cell surfaces, which elongate upon encountering target cells while maintaining a short length when contacting competing cells, as directed by a strand-displacement reaction arranged on target cell surfaces. With the display of ligands that bind to both target and competing cells, the contact-induced, region-selective fibril elongation selectively promotes host-target cell interactions via the accumulation of nonspecific ligands between matched cells. This approach is effective in guiding natural killer cells, the broad-spectrum effector lymphocytes, to eliminate specific cancer cells. In contrast to conventional methods relying on target cell-specific binding molecules for the desired cellular interactions, this dynamic scaffold-based approach would broaden the scope of cell combinations for manipulation and enhance the adjustability of cell behaviors for future applications.

Encapsulation of human natural killer cells into novel gelatin-based polymeric hydrogel networks.

In the innate immune system, natural killer (NK) cells are effector lymphocytes which control several tumor types and microbial infections by limiting disease spread and tissue damage. With tumor cell killing abilities, with no priming or prior activation, NKs are potential anti-cancer therapies. In clinical practice, NKs are used in intravenous injections as they typically grow as suspension, similar to other blood cells. In this study, we designed a novel and effective biomaterial-based platform for NK cell delivery, which included in-situ NK cell encapsulation into three-dimensional (3D) biocompatible polymeric scaffolds for potential anti-cancer treatments. Depending on physical cross-linking between an alginate (ALG) polymer and a divalent cation, two natural polymers (gelatin (GEL) and hyaluronic acid (HA)) penetrated into pores and generated an inter-penetrating hydrogel system with improved mechanical properties and stability. After extensive characterization of hydrogels, NK cells were encapsulated inside using our in-situ gelation procedure to provide a biomimetic microenvironment.&#xD.

Berberine Protects against Hepatocellular Carcinoma Progression by Regulating Intrahepatic T Cell Heterogeneity.

Accumulating evidence suggests that berberine (BBR) exhibits anti-cancer effects in hepatocellular carcinoma (HCC). However, the mechanisms by which BBR regulates the immunological microenvironment in HCC has not been fully elucidated. In this study, a mouse model of orthotopic HCC is established and treated with varying doses of BBR. BBR showed effectiveness in reducing tumor burden in mice with HCC. Cytometry by time-of-flight depicted the alterations in the tumor immune landscape following BBR treatment, revealing the enhancement in the T lymphocytes effector function. In particular, BBR decreased the proportion of TCRbhiPD-1hiCD69+CD27+ effector CD8+ T lymphocytes and increased the proportion of Ly6ChiTCRb+CD69+CD27+CD62L+ central memory CD8+ T lymphocytes. Single-cell RNA sequencing further elucidates the effects of BBR on transcriptional profiles of liver immune cells and confirms the phenotypical heterogeneity of T lymphocytes in HCC immune microenvironment. Additionally, it is found that BBR potentially regulated the antitumor immunity in HCC by modulating the receptor-ligand interaction among immune cells mediated by cytokines. In summary, the findings improve the understanding of BBR's impact on protecting against HCC, emphasizing BBR's role in regulating intrahepatic T cell heterogeneity. BBR has the potential to be a promising therapeutic strategy to hinder the advancement of HCC.

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

BackgroundCancer 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.MethodsCSCs 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.ResultsWe 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.ConclusionsThis 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.

The role of сhemokine CX3CL1/Fractalkine in chronic viral hepatitis B

Hepatitis B is an infectious disease resulting from infection with the hepatitis B virus. Chronic hepatitis B (CHB) is characterized by prolonged inflammation in the liver, the development of fibrosis, liver cirrhosis and hepatocellular carcinoma. Factors of the immune system play a critical role in the pathogenesis of CHB. Thanks to chemokines, immune cells migrate to the site of inflammation to implement their effector functions. The CX3CL1/Fractalkine chemokine is the only member of the CX3C family of chemokines with unique structural and functional properties. Its receptor CX3CR1 is expressed mainly on the surface of cytotoxic effector lymphocytes such as NK cells, TNK and cytotoxic T lymphocytes. The purpose of our study was to analyze the content of CX3CL1/Fractalkine in the blood plasma of patients with CHB and the analysis of this chemokine with liver fibrosis. The concentration of CX3CL1/Fractalkine was determined in the blood plasma of patients with CHB using a multiplex assay based on xMAP technology. Blood plasma from patients with chronic viral hepatitis C (CHC) and autoimmune liver diseases (AILD) was used as a comparison group. The control group consisted of healthy individuals. For statistical analysis of data, nonparametric statistics methods were used: Kruskal–Wallis test, Spearman correlation coefficient ROC-analysis. It was shown a reduced level of CX3CL1/Fractalkine in patients with CHB compared with the control group (p = 0.0003) and with the comparison groups of CHC (p 0.0001) and AILD (p = 0.0005). A reduced concentration of CX3CL1/Fractalkine was shown in the blood plasma of CHB patients with initial fibrosis (p = 0.0092) and severe fibrosis/cirrhosis (p = 0.0009), while in patients with severe fibrosis/cirrhosis, a significantly reduced level of this chemokine was established compared with the initial degree of liver fibrosis (p = 0.0081). Correlation analysis revealed a highly significant inverse relationship between the severity of liver fibrosis and the content of CX3CL1/Fractalkine in the blood plasma of patients with CHB (Spearman r = –0.33; p = 0.02). Thus, the chemokine CX3CL1/Fractalkine is included in the immunopathogenesis of CHB; its reduced content is characteristic only of CHB and does not change in other chronic liver diseases. It is involved in the processes of liver fibrosis during infection with the hepatitis B virus. The concentration of the chemokine CX3CL1/Fractalkine depends on the stage of liver fibrosis in CHB, and a decrease in the level of CX3CL1/Fractalkine in the blood plasma can serve as a negative factor in the development of CHB.

Comparison of T cell maturation profiles in the 1st and 5th wave of COVID-19 in the Polish population.

The coronavirus pandemic has become the most critical global health threat of this century and the greatest challenge to the human population. The search for simple and quick diagnostic methods enabling the identification of patients infected with the SARS-CoV-2 virus may be a valuable method to track infection. The aim of the study was the clinical and immunological characterization of patients by assessing the degrees of maturity of T lymphocytes from the 1st and 5th waves of coronavirus disease 2019 (COVID-19) in comparison to a healthy control group (HC). We determined leukocyte and T lymphocyte subpopulations (recent thymic emigrant (RTE), naïve, effector, central memory and effector memory) in patients from the 1st COVID-19 wave (n = 23), the 5th COVID-19 wave (n = 38) and HC (n=20) using a panel of monoclonal antibodies using multiparameter flow cytometry. We observed a lower median proportion of lymphocytes and NK cells, and elevated percentage and number of neutrophils in patients from the 5th wave compared to the 1st. We found a reduced percentage of CD4+ effector memory cells in the 1st wave group compared to the 5th wave (14.1 vs 23.2, p < 0.05), and a higher percentage of RTE and naïve CD8+ cells in the 1st wave compared to the 5th wave (p < 0.05). The effector memory CD8+ cells were highest in the 5th wave compared to both 1st wave and HC patients (respectively, 35.1 vs 18.1 vs 19.3%, p < 0.05). The 5th wave group showed significantly more differences compared to HC. Our results showed a clear increase of effector cells with a simultaneous decrease in virgin T cells in the 5th COVID-19 infection. Monitoring lymphocyte subsets during infection allows assessment of the patient's immune status and of readiness of lymphocytes to respond to the immune response, and may be necessary to improve clinical outcomes.

Low-Dose Ionizing γ-Radiation Elicits the Extrusion of Neutrophil Extracellular Traps.

Patients with cancer frequently undergo radiotherapy in their clinical management with unintended irradiation of blood vessels and copiously irrigated organs in which polymorphonuclear leukocytes circulate. Following the observation that such low doses of ionizing radiation are able to induce neutrophils to extrude neutrophil extracellular traps (NET), we have investigated the mechanisms, consequences, and occurrence of such phenomena in patients undergoing radiotherapy. NETosis was analyzed in cultures of neutrophils isolated from healthy donors, patients with cancer, and cancer-bearing mice under confocal microscopy. Cocultures of radiation-induced NETs, immune effector lymphocytes, and tumor cells were used to study the effects of irradiation-induced NETs on immune cytotoxicity. Radiation-induced NETs were intravenously injected to mice for assessing their effects on metastasis. Circulating NETs in irradiated patients with cancer were measured using ELISA methods for detecting MPO-DNA complexes and citrullinated histone 3. Irradiation of neutrophils with very low γ-radiation doses (0.5-1 Gy) elicits NET formation in a manner dependent on oxidative stress, NADPH oxidase activity, and autocrine IL8. Radiation-induced NETs interfere with NK cell and T-cell cytotoxicity. As a consequence, preinjection of irradiation-induced NETs increases the number of successful metastases in mouse tumor models. Increases in circulating NETs were readily detected in two prospective series of patients following the first fraction of their radiotherapy courses. NETosis is induced by low-dose ionizing irradiation in a neutrophil-intrinsic fashion, and radiation-induced NETs are able to interfere with immune-mediated cytotoxicity. Radiation-induced NETs foster metastasis in mouse models and can be detected in the circulation of patients undergoing conventional radiotherapy treatments. See related commentary by Mowery and Luke, p. 3965.

Moderate-intensity aerobic exercise training improves CD8+ tumor-infiltrating lymphocytes effector function by reducing mitochondrial loss

Aerobic exercise training (AET) has emerged as a strategy to reduce cancer mortality, however, the mechanisms explaining AET on tumor development remain unclear. Tumors escape immune detection by generating immunosuppressive microenvironments and impaired Tcell function, which is associated with Tcell mitochondrial loss. AET improves mitochondrial content and function, thus we tested whether AET would modulate mitochondrial metabolism in tumor-infiltrating lymphocytes (TIL). Balb/c mice were subjected to a treadmill AET protocol prior to CT26 colon carcinoma cells injection and until tumor harvest. Tissue hypoxia, TIL infiltration and effector function, and mitochondrial content, morphology and function were evaluated. AET reduced tumor growth, improved survival, and decreased tumor hypoxia. An increased CD8+ TIL infiltration, IFN-γ and ATP production promoted by AET was correlated with reduced mitochondrial loss in these cells. Collectively, AET decreases tumor growth partially by increasing CD8+ TIL effector function through an improvement in their mitochondrial content and function.

Can magnetic nanoparticles enhance adoptive cell therapy via driving migration of lymphocytes into tumors?

Therapy of malignant tumors still represents a huge problem for healthcare, since these diseases lead to a high rate of disability and premature death of the population. The main problems of adoptive cell therapy for malignant tumors are a low rate of migration of effector lymphocytes into tumors, as well as their low activity in tumors due to suppressive tumor microenvironment. In addition, it should be noted that systemic intravenous administration of a large number of activated lymphocytes may be accompanied by a pronounced cytokine release syndrome, which leads to significant negative side effects, including high temperature, blood clotting disorders, aggression of immune cells against their own tissues, even neurotoxicity. Functional nanomaterials, such as magnetic nanoparticles with various surface modifications (PEG, PEI, DMSA, citrate, etc.) are highly promising agents for targeted delivery of different anti-tumor substances. Magnet-driven enrichment of effector anti-tumor lymphocytes in tumors would highly increase the effectiveness and enhance safety of adoptive lymphocyte therapy. However, different research groups obtained opposing data about the feasibility and efficiency of such approach. Thus, this review is focused on experimental details of the contradicting studies and aims to elucidate the possible reasons of these controversies and the best practices to efficiently target lymphocytes into tumors.

Chromatin remodeler ACTL6A in CD8+ T cells promotes antitumor immunity

Abstract Chromatin remodeling plays a pivotal role in dictating epigenetic and transcriptomic regulation governing cytotoxic T lymphocyte differentiation and effector function. However, the regulatory mechanisms underlying chromatin remodeler assembly and actions remains unclear. Actin-like gene family members have been implicated in the organization of chromatin landscapes, however their role in T cell functional regulation remains unknown. We identified Actin-like protein 6A/Actl6a as the most upregulated gene within actin-like family members upon CD8+ T cell activation across multiple species. Additionally, ACTL6A is highly expressed in human tumor-infiltrating CD8+ mitotic tissue-resident memory T cells, suggesting a functional importance of ACTL6A in this subset. Deletion of mouse Actl6a in mature T lymphocytes impairs immune responses to transplanted syngeneic mouse tumors. T cell-specific Actl6a deletion mice exhibit a reduced effector memory population and attenuated cytotoxicity in their tumor infiltrating CD8+ T cells. T cell adoptive transfer further corroborates a CD8+ T cell-intrinsic role of Actl6a on antitumor adaptive immunity. Transcriptomic/epigenetic investigations provide mechanistic insights into the action of ACTL6 in the CD8+ T cells regulation. Furthermore, our study suggests that pharmacological or genetic approaches to increase Actl6a expression in CD8+ T cells may have the potential to boost immune based anticancer therapies including CAR-T therapies.

Abstract LB066: Acute systemic beta-adrenergic receptor activation to improve graft composition and outcomes in hematopoietic stem cell transplantation

Abstract Background: Graft-versus-host disease (GvHD) and relapse persist as significant hurdles in achieving successful outcomes following allogeneic hematopoietic cell transplantation (alloHCT). The composition of the graft plays a substantial role in influencing transplant outcomes. Higher numbers of naïve CD4 and naïve CD8 T cells correlate with increased GvHD risk, conversely, elevated numbers of NK cells are associated with enhanced graft-versus-leukemia (GvL) effects. Acute systemic β-adrenergic receptor activation triggers the mobilization of favorable effector lymphocytes into the bloodstream, leading to a significant alteration in the composition of circulating immune cells. Aim: This study investigated whether infusion with the non-selective beta-agonist isoproterenol (ISO), following granulocyte colony-stimulating factor (G-CSF) mobilization, would enhance human peripheral blood hematopoietic cell (PBHC) grafts and improve transplant outcomes in NSG mice. Methods: Ten healthy volunteers received ISO infusion (50 ng/kg/min) for 20 minutes after 5 days of G-CSF. Blood samples were collected before and during the last 5 minutes of ISO infusion. Results: ISO infusion increased the total number of G-CSF-mobilized CD34 cells (28±13 cell/µl to 32±13 cells/µl) and significantly improved G-CSF-mobilized PBHC composition, increasing favorable graft cell subsets—NK cells (9.5% to 27.9%) and γδ T cells (5.0% to 7.5%)—and reducing unfavorable graft components—B cells (12.6% to 7.7%), naïve CD4 (18.1% to 11.2%), and naïve CD8 (8.9% to 5.8%) T cells (all p&amp;lt;0.05). NSG mice receiving G-CSF+ISO mobilized grafts exhibited lower GvHD (P=0.012) and extended survival (median survival: G-CSF alone = 45 days, G-CSF+ISO = 78 days) compared to mice receiving grafts mobilized by G-CSF alone. No difference in human CD45 engraftment was observed between the groups, with ~50% engraftment in both groups of mice. Upon challenge with the K562 chronic myeloid leukemia cell line, 42% of NSG-Tg(Hu-IL15) mice receiving G-CSF+ISO mobilized grafts were alive with low tumor burden at day 40, compared to 15% of mice receiving G-CSF mobilized grafts. In vitro, PBHC mobilized by G-CSF+ISO demonstrated an 8-fold increase in cytolysis against K562 compared to PBHC mobilized by G-CSF only (P=0.0002). Conclusion: ISO infusion post-G-CSF treatment favorably enhances graft composition, mitigates GvHD, prolongs survival, and augments GvL effects. Our findings suggest that acute systemic beta-adrenergic receptor activation could be a valuable strategy to enhance outcomes in alloHCT. Citation Format: Helena Batatinha, Grace M. Niemiro, Nicole Pena, Giovannah Hoskin, Preteesh Mylabathula, Forrest Baker, Tiffany Zuniga, Kyle Smith, Douglass Diak, Michael Seckeler, Emmanuel Katsanis, Richard Simpson. Acute systemic beta-adrenergic receptor activation to improve graft composition and outcomes in hematopoietic stem cell transplantation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB066.

Tissue-resident memory NK cells: Homing in on local effectors and regulators.

Natural killer (NK) cells are the prototype innate effector lymphocyte population that plays an important role in controlling viral infections and tumors. Studies demonstrating that NK cells form long-lived memory populations, akin to those generated by adaptive immune cells, prompted a revaluation of the potential functions of NK cells. Recent data demonstrating that NK cells are recruited from the circulation into tissues where they form long-lived memory-like populations further emphasize that NK cells have properties that mirror those of adaptive immune cells. NK cells that localize in non-lymphoid tissues are heterogeneous, and there is a growing appreciation that immune responses occurring within tissues are subject to tissue-specific regulation. Here we discuss both the immune effector and immunoregulatory functions of NK cells, with a particular emphasis on the role of NK cells within non-lymphoid tissues and how the tissue microenvironment shapes NK cell-dependent outcomes.

Abstract 1582: Cabozantinib changes the tumor microenvironment to increase the efficacy of immunotherapy in refractory metastatic pancreatic ductal adenocarcinoma

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies. Tumors evade immune surveillance by expressing PD-L1 that interacts with the T cell protein PD-1, subsequently inhibiting CD8+ cytotoxic T lymphocyte proliferation and effector function. A plausible reason for this observation may be that other, redundant, immune suppressive mechanisms are at play. Our research team has shown that elevated infiltration of polymorphonuclear (PMN)-MDSCs within the PDAC tumor microenvironment (TME) inhibit T cell effector function, regardless of PD-1/PD-L1 inhibition (Holokai et al., 2020). Objective: A Phase II clinical trial was developed to identify the potential therapeutic benefit of combinatorial anit-PD-L1/PD-1 and cabozantinib (cabo) treatment in therapy-resistant (refractory and metastatic) PDAC patients. Methods: NanoString CosMx™ spatial molecular transcriptomic imaging (CosMx™ SMI) was performed using FFPE sections collected from a liver or lung metastatic target lesions at visit 1 (pretreatment) and visit 2 (9 weeks on combinatorial treatment) from individual patients. FFPE sections were prepared from the same target lesion, and fields of view were chosen on the H&amp;E in consultation with GI pathologist. Seurat V 4.0 was used for the analysis and visualization by spatial mapping of each FOV showing identified cell population indicated by color coding in visit 1 and visit 2 within the same patient. Multiplex immunofluorescence (MxIF) of patient FFPE tissues and single cell RNA sequencing (scRNAseq) of PDAC organoids (PDOs) generated from the core biopsies collected at visit 1 and matched visit 2 from each patient were used to validate the CosMx™ SMI data. Results: A uniform manifold approximation and projection showed loss of tumor cell populations within the PDAC TME in response to combinatorial treatment compared to pretreatment visit 1. Comparison between spatial maps of visit 1 to visit 2 demonstrated a shift in cell populations within defined NICHES (local cellular TME) whereby there was 1) a loss of tumor cell populations, 2) increase in CTL infiltration, 3) increase in endothelial cells, 4) decrease immunosuppressive MDSCs, 5) decrease in antigen presenting CAFs, and 6) change in myCAFs to an inflammatory CAF phenotype. Within the iCAF population IL-6, CXCL1, LIFR, ACTA2 and FAK were expressed; correlating with an increase in CD8 perforin and granzyme B positive cells in response to cabo and checkpoint inhibition. MxIF, spectral flow cytometry and scRNAseq analyses of the matched in vitro PDO model showed tumor cell death that correlated with decreased MDSC viability, increased CTL proliferation and a shift in CAF phenotypes. Conclusion: These findings suggest that cabo induces a TME conducive to increased response to immunotherapy in PDAC patients with refractory metastatic disease. Citation Format: Jayati Chakrabarti, Pritha Adhikary, Jiang Wang, Davendra Sohal, Syed A. Ahmad, Junaid Arshad, Aaron J. Scott, Rachna T. Shroff, Yana Zavros. Cabozantinib changes the tumor microenvironment to increase the efficacy of immunotherapy in refractory metastatic pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1582.

Abstract 1521: Chromatin remodeler ACTL6A in CD8+ T cells promotes antitumor immunity

Abstract Chromatin remodeling plays a pivotal role in dictating epigenetic and transcriptomic regulation governing cytotoxic T lymphocyte differentiation and effector function. However, the regulatory mechanisms underlying chromatin remodeler assembly and actions remains unclear. Actin-like gene family members have been implicated in the organization of chromatin landscapes, however their role in T cell functional regulation remains unknown. We identified Actin-like protein 6A/Actl6a as the most upregulated gene within actin-like family members upon CD8+ T cell activation across multiple species. Additionally, ACTL6A is highly expressed in human tumor-infiltrating CD8+ mitotic tissue-resident memory T cells, suggesting a functional importance of ACTL6A in this subset. Deletion of mouse Actl6a in mature T lymphocytes impairs immune responses to transplanted syngeneic mouse tumors. T cell-specific Actl6a deletion mice exhibit a reduced effector memory population and attenuated cytotoxicity in their tumor infiltrating CD8+ T cells. Heterozygous deletion of Actl6a displays an intermediate reduction of effector memory population and cytotoxicity between that of wildtype and homozygous knockout, indicating that ACTL6A acts in a dose-dependent manner to promote CD8+ effector cell fate. T cell adoptive transfer further corroborates a CD8+ T cell-intrinsic role of Actl6a on antitumor adaptive immunity. Currently, we are investigating the chromatin landscape and transcriptomic changes upon loss of Actl6a using ATAC-seq and RNA-seq. Furthermore, the dose dependency of Aclt6a on CD8+ T cell effector function suggests that pharmacological or genetic approaches to increase Actl6a expression in CD8+ T cells may have the potential to boost immune based anticancer therapies including CAR-T therapies. Citation Format: Bogang Wu, Win Thant, Elena Bitman, Ting Liu, Leif W. Ellisen. Chromatin remodeler ACTL6A in CD8+ T cells promotes antitumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1521.

Abstract 6733: Multiomics analysis of impact of CD8+ and other cell populations in STING agonist treated ex vivo mesothelioma samples

Abstract Background: Collective evidence highlights that agonism of the host STING pathway plays a critical role in eliciting robust and durable anti-tumor immunity. Dazostinag (TAK-676) is a novel systemically delivered STING agonist that ignites the innate immune system and mobilizes adaptive immunity. Preclinical studies with dazostinag demonstrated a strong, persistent CD8+ T cell anti-tumor response driven by innate immune derived type I IFN and pro-inflammatory cytokines. The role of CD8+ T cells in response to dazostinag was further supported by a previously demonstrated correlation between response and CD8+ T cell frequency in a patient-derived organotypic tumor spheroids (PDOTS) model of mesothelioma. Within the current work, we sought to determine the extent to which response to dazostinag in mesothelioma depends on CD8+ T cells versus the contribution of other immune cells. Methods: Surgical mesothelioma cases were collected along with clinicopathological variables at Brigham and Women’s Hospital under an IRB-approved protocol. PDOTS were generated as described previously. Ex vivo response was determined by fluorescent life/dead imaging, and orthogonally evaluated by multiplexed cytokine array, immunofluorescence, and flow cytometry; subset of tumors was studied using single cell RNA sequencing (scRNAseq). Results: Dazostinag-driven tumor cell killing was evaluated in 20 mesothelioma PDOTS. 11 samples were characterized as responders (R) with a cut-off of &amp;gt;30% reduction in live cell area; 9 as non-responders (NR). In 12 out of 20 PDOTS, CD8 neutralization effect was assessed: four were TAK-676 NR, and out of 8 R 4 had at least 20% killing abrogated by aCD8. Effect did not depend on the baseline amount of CD8+ T cells in the sample. scRNAseq analysis showed that R and NR T cells have different activation/exhaustion phenotypes and varying levels of interferon stimulated genes (ISG) in response to STING agonism. Other cell populations emerged as candidates for dazostinag resistance: NR cases carried remodeled immunosuppressive myeloid cells or matrix metalloproteinases-expressing fibroblasts. In general, myeloid cell abundance at baseline characterized by flow had a trend in negatively correlating with dazostinag response. Intrinsic expression of type I interferons shown by multiplexed cytokine array was linked to dazostinag sensitivity (R vs. NR IFN-β p=0.028; IFNα2a p=0.016) and can potentially be used as a predictor for response. Conclusion: We evaluated immune modulations in mesothelioma after treatment with a systemic STING agonist dazostinag using human tumor ex vivo culture. Innate interferon type I expression was higher in responding samples. TAK-676 efficacy was partially reduced in absence of effector lymphocytes, however other cells, such as immunosuppressive myeloid cells and fibroblasts, can have a negative impact on dazostinag response in mesothelioma. Citation Format: Elena Ivanova, Sung R. Park, Ari P. Zlota, Nathaniel Spicer, Minh Ha, Sophie Kivlehan, Iliana Gjeci, Simona Innocenti, Lauren Zasadil, Patrick Lizotte, Michael Y. Tolstorukov, Kai Ding, Adnan O. Abu-Yousif, Jeffrey Raizer, Vicky A. Appleman, Raphael Bueno, David A. Barbie, Cloud P. Paweletz. Multiomics analysis of impact of CD8+ and other cell populations in STING agonist treated ex vivo mesothelioma samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6733.

Abstract 75: Luciferase reporter cell lines allow simultaneous incorporation of tumor cells, innate immune cells, and adaptive immune cells for in-depth immune checkpoint studies

Abstract Despite the considerable success of immune checkpoint therapies targeting T cells, a sizable proportion of patients experience resistance or relapse due to the immunosuppressive nature of the tumor microenvironment. Myeloid cells, a major component that suppresses effector lymphocytes, have emerged as an alternative and promising therapeutic target. However, there is a deep lack of widely accessible immunological models capable of representing the intricate three-way interaction between tumor cells, T cells, and myeloid cells. To address this need, we conducted a comprehensive protein profiling of human tumor and immune cell lines available at ATCC for various established and novel immune checkpoint molecules. Cell lines with high endogenous expression of the immune checkpoint proteins, such as programmed death-ligand 1 and 2 (PD-L1 and PD-L2), cluster of differentiation 155 (CD155), B7 homolog 3 (B7-H3), sialic acid-binding Ig-like lectin 10 (Siglec-10), or signal-regulatory protein alpha (SIRPα), were selected and constructed into luciferase reporter cell lines. For tumor reporter cell lines, a gamma interferon activation site (GAS) response element was placed upstream of the luciferase gene in the lentiviral vector, enabling the activation of the JAK-STAT signaling pathway within tumor cells to induce luciferase expression. In myeloid reporter cell lines, a nuclear factor kappa B (NF-κB) response element replaced GAS to monitor the activation of the NF-κB signaling pathway. In the presence of corresponding immune checkpoint inhibitors that enhance T cell-mediated anti-tumor activity, these reporter cell lines produce a bioluminescent signal based on luciferase expression. This signal can be easily detected and quantified to assess the efficacy of the inhibitor. Our data revealed that bioluminescence intensity in the tumor and myeloid reporter cell lines increased by &amp;gt;100-fold in a dose-dependent manner in response to interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) stimulation, respectively, and by &amp;gt;50-fold in response to the conditioned media collected from activated primary T cells. Furthermore, in co-culture assays involving various combinations of immune cell and tumor cell types with corresponding immune checkpoint inhibitors, these reporter cell lines demonstrated a significant increase in bioluminescence intensity. In conclusion, these newly established luciferase reporter cell lines offer an excellent ex vivo model for cancer immunotherapy. These cell lines naturally express immune checkpoint proteins, enabling the sensitive and reproducible monitoring of combinatorial responses from various immune cell types. Citation Format: Hyeyoun Chang, Alicia C. Walker, John G. Foulke, Luping Chen, Fang Tian, Zhizhan Gu. Luciferase reporter cell lines allow simultaneous incorporation of tumor cells, innate immune cells, and adaptive immune cells for in-depth immune checkpoint studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 75.