Cytolytic Effector Research Articles

Comparative Analysis of Extracellular Vesicles from Cytotoxic CD8+ αβ T Cells and γδ T Cells.

Although belonging to different branches of the immune system, cytotoxic CD8+ αβ T cells and γδ T cells utilize common cytolytic effectors including FasL, granzymes, perforin and granulysin. The effector proteins are stored in different subsets of lysosome-related effector vesicles (LREVs) and released to the immunological synapse upon target cell encounter. Notably, in activated cells, LREVs and potentially other vesicles are continuously produced and released as extracellular vesicles (EVs). Presumably, EVs serve as mediators of intercellular communication in the local microenvironment or at distant sites. EVs of activated and expanded cytotoxic CD8+ αβ T cells or γδ T cells were enriched from culture supernatants by differential and ultracentrifugation and characterized by nanoparticle tracking analyses and Western blotting. For a comparative proteomic profiling, EV preparations from both cell types were isobaric labeled with tandem mass tags (TMT10plex) and subjected to mass spectrometry analysis. 686 proteins were quantified in EV preparations of cytotoxic CD8+ αβ T cells and γδ T cells. Both populations shared a major set of similarly abundant proteins, while much fewer proteins presented higher abundance levels in either CD8+ αβ T cells or γδ T cells. To our knowledge, we provide the first comparative analysis of EVs from cytotoxic CD8+ αβ T cells and γδ T cells.

IMG-11. RADIOGENOMIC ANALYSIS INFORMS ON IMMUNOLOGICAL PROFILES, PROGNOSIS, AND TREATMENT RESPONSE IN PEDIATRIC LOW-GRADE GLIOMA

Abstract BACKGROUND Pediatric low-grade gliomas (pLGGs) have variable prognosis and treatment responses. Complete resection cannot be achieved for all tumors, especially for highly infiltrative or deep-seated tumors, necessitating additional therapy, from chemotherapy to targeted inhibitors. We integrated imaging-derived phenotypes with genotypic traits from transcriptional analysis, offering an in-depth characterization of pLGG immune microenvironment, progression risk, and likelihood of multiple treatments. METHODS Analyzing 549 treatment-naïve pLGGs with multiparametric MRI and RNA sequencing, we identified distinct immunological groups using XCell scores based on immune cell infiltration. We developed a radiomic signature using conventional MRI and machine learning techniques (support vector machines with a linear kernel and nested cross-validation) to distinguish the ‘immune-hot’ group, and incorporated diffusion MRI to improve signature accuracy. Additionally, a clinicoradiomic model predicting tumor progression risk and treatment response was trained, integrating clinical and radiomic data. Transcriptomic analysis was conducted to identify pathways correlated with clinicoradiomic risk, predictive of pLGG progression. RESULTS Three immunological groups were revealed, the ‘immune-hot’ group characterized by poor prognosis due to a high concentration of pro-tumorigenic M2-polarized macrophages, despite a higher preponderance of T-lymphocytes. The radiomic signature effectively distinguished the ‘immune-hot’ group with balanced accuracies of 76.8%/86.0% in discovery/replication sets, improved by diffusion MRI to 81.5%/84.4%. The clinicoradiomic model showed concordance indices of 0.71 (discovery) and 0.77 (replication), predicting patient progression risk. Significant differences (p=0.0010) were found in clinicoradiomic risk scores between patients undergoing one versus multiple treatments post-diagnosis, linking higher scores to a likelihood of multiple treatments. Transcriptomic pathways associated with higher clinicoradiomic risk highlighted the importance of fatty acid oxidation, a tumor-promoting mechanism that drives adaptive resistance to cytolytic immune cell effectors. CONCLUSIONS This first large-scale radiogenomic analysis in pLGGs aids in prognostication, assessing progression risk, predicting treatment response to standard-of-care therapies, and stratification of patients to identify potential candidates for novel therapies targeting aberrantly regulated pathways.

Neutrophil-mediated hypoxia drives pathogenic CD8+ T cell responses in cutaneous leishmaniasis.

Cutaneous leishmaniasis caused by Leishmania parasites exhibits a wide range of clinical manifestations. Although parasites influence disease severity, cytolytic CD8+ T cell responses mediate disease. Although these responses originate in the lymph node, we found that expression of the cytolytic effector molecule granzyme B was restricted to lesional CD8+ T cells in Leishmania-infected mice, suggesting that local cues within inflamed skin induced cytolytic function. Expression of Blimp-1 (Prdm1), a transcription factor necessary for cytolytic CD8+ T cell differentiation, was driven by hypoxia within the inflamed skin. Hypoxia was further enhanced by the recruitment of neutrophils that consumed oxygen to produce ROS and ultimately increased the hypoxic state and granzyme B expression in CD8+ T cells. Importantly, lesions from patients with cutaneous leishmaniasis exhibited hypoxia transcription signatures that correlated with the presence of neutrophils. Thus, targeting hypoxia-driven signals that support local differentiation of cytolytic CD8+ T cells may improve the prognosis for patients with cutaneous leishmaniasis, as well as for other inflammatory skin diseases in which cytolytic CD8+ T cells contribute to pathogenesis.

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

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

Immunogenic Material Vaccine for Cancer Immunotherapy by Structure-Dependent Immune Cell Trafficking and Modulation.

Inherently immunogenic materials offer enormous prospects in enhancing vaccine efficacy. However, the understanding and improving material adjuvanticity remain elusive. Herein how the structural presentation of immunopotentiators in a material governs the dynamic dialogue between innate and adaptive immunity for enhanced cancer vaccination is reported. The immunopotentiator manganese into six differing structures that resemble the architectures of two types of pathogens (spherical viruses or rod-like bacteria) is precisely manipulated. The results reveal that innate immune cells accurately sense and respond to the architectures, of which two outperformed material candidates (151nm hollow spheres and hollow microrods with an aspect ratio of 4.5) show higher competence in creating local proinflammatory environment with promoted innate immune cell influx and stimulation on dendritic cells (DCs). In combination with viral peptides, model proteins, or cell lysate antigens, the outperformed microrod material remarkably primes antigen-specific CD8 cytolytic T cells. In prophylactic and therapeutic regimens, the microrod adjuvanted vaccines display optimal aptitude in tumor suppression in four aggressive murine tumor models, by promoting the infiltration of heterogeneous cytolytic effector cells while decreasing suppressive immunoregulatory populations in tumors. This study demonstrates that a rationally selected architecture of immunogenic materials potentially advances the clinical reality of cancer vaccination.

Preclinical Development of CAR T Cells with Antigen-Inducible IL18 Enforcement to Treat GD2-Positive Solid Cancers.

Cytokine-engineering of chimeric antigen receptor-redirected T cells (CAR T cells) is a promising principle to overcome the limited activity of canonical CAR T cells against solid cancers. We developed an investigational medicinal product, GD2IL18CART, consisting of CAR T cells directed against ganglioside GD2 with CAR-inducible IL18 to enhance their activation response and cytolytic effector functions in the tumor microenvironment. To allow stratification of patients according to tumor GD2 expression, we established and validated immunofluorescence detection of GD2 on paraffin-embedded tumor tissues. Lentiviral all-in-one vector engineering of human T cells with the GD2-specific CAR with and without inducible IL18 resulted in cell products with comparable proportions of CAR-expressing central memory T cells. Production of IL18 strictly depends on GD2 antigen engagement. GD2IL18CART respond to interaction with GD2-positive tumor cells with higher IFNγ and TNFα cytokine release and more effective target cytolysis compared with CAR T cells without inducible IL18. GD2IL18CART further have superior in vivo antitumor activity, with eradication of GD2-positive tumor xenografts. Finally, we established GMP-compliant manufacturing of GD2IL18CART and found it to be feasible and efficient at clinical scale. These results pave the way for clinical investigation of GD2IL18CART in pediatric and adult patients with neuroblastoma and other GD2-positive cancers (EU CT 2022- 501725-21-00). See related commentary by Locatelli and Quintarelli, p. 3361.

Abstract CT093: Vaccine immunotherapy by homologous antigenic loading as adjuvant therapy for glioblastoma: Ongoing phase I analysis

Abstract Glioblastoma (GBM) is a devastating tumor of the central nervous system (CNS) for which median survival remains 14-18 months despite aggressive standard of care. Early clinical studies of dendritic cell (DC) vaccination for the adjuvant treatment of GBM previously suggested mild to moderate clinical benefit, but results were both inconsistent and inconclusive. Homologous antigenic loading is an ex vivo technique that leverages p38MAPK and mTORC1 signaling cascades to initiate powerful cDC1-like skewing in monocyte-derived DC, leading to downstream induction of CD161int CD8+ cytolytic memory effectors. Here we report ongoing results of a completed phase I clinical trial with minimal exclusion criteria in which dendritic cell vaccines were prepared through homologous antigenic loading and administered to newly-diagnosed patients bilaterally in the vicinity of the deep cervical lymph nodes, assisted by ultrasound sonography. Patients were additionally adjuvanted with six weeks of concurrent type I interferon. Four dose levels from 3.5 x 106 to 3.6 x 107 total vaccine cells were tested, none of which resulted in AEs > grade 2 attributable to the investigational regimen. Immunohistochemistry of tumors derived from early post-vaccination second resections displayed enhanced CD8+ T-cell infiltration and pathologic findings consistent with residual rather than relapsed GBM in 2/3 patients. Radiologic pseudoprogression was also routinely observed among patients of all cohorts. Analysis of post-vaccination circulating PBMC indicated expansion of both CD4+ and CD8+ central memory T-cell compartments (p<0.05 for each by student’s two-tailed t-test) as well as expansion of CD8+CD127+ T-cells (p<0.05 by student’s two tailed t-test) in 4/4 patients analyzed. With an average of 10.9 months follow-up, median survival of this largely MGMT promoter unmethylated cohort was not yet reached and was statistically greater (p<0.05 by log-rank[Mantle-Cox]) than that of matched historical controls. At the time of submission, 13/15 trial patients remained alive with ECOG </= 2. The results suggest that modern dendritic cell vaccines are safe, potentially efficacious, and can be effectively integrated within existing standards of care. Citation Format: Joseph F. Georges, Mazen Zaher, Corey M. Mossop, Christopher J. Bilbao, Christina M. Clay, Sabina Amin, Hamza A. Shaikh, Akshar Trivedi, Wei Liu, Madhuri Namekar, Colby J. Hofferek, Keenan Ernste, Eva H. Schumann, Mia Vu, Damilola Oyewole-Said, Nalini Bisht, Jonathan Vazquez-Perez, Ashley M. Goralczyk, Lindsey Colman, Lynne S. Kohler, Thuy V. Cao, Ngozi Okereke, Benjamin L. Musher, Vinod Ravi, Jan O. Kemnade, Rodrick C. Zvavanjanja, Jay-Jiguang Zhu, Sigmund H. Hsu, Yoshua Esquenazi-Levy, Nitin Tandon, Alan Turtz, Vanaja Konduri, William Karl Decker. Vaccine immunotherapy by homologous antigenic loading as adjuvant therapy for glioblastoma: Ongoing phase I analysis [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 CT093.

Abstract LB358: Program and epigenetic control of stemness and exhaustion of tumor infiltrating CD8+ T lymphocyte

Abstract Tumor infiltrating CD8+ T lymphocytes (TILs) develop a state of exhaustion, become terminally exhausted (Ttex) and fail to control tumor growth through cytolytic activity. At an early stage, however, progenitors of exhausted (pTex) TILs are renewable and still reprogrammable, and can generate efficient cytolytic effector cells. pTex highly express stemness program genes. There is a high interest in understanding the mechanisms that control stemness and exhaustion programs of TILs. In the current study we investigated the consequences of the removal of the transcription factor (TF) BCL11B in TILs on the control of the stemness and exhaustion programs, their epigenetics landscape, and the impact on the pTex versus Ttex TIL status. Using scRNAseq, bulk RNAseq and epigenomics approaches, we positioned BCL11B upstream of essential TFs of the stemness and exhaustion programs, as well as of the cytolytic activity program. BCL11B-/- CD8+ TILs have increased stemness and elevated effector program, but reduced exhaustion, and they promoted a superior response compared to WT TILs, restricting tumor growth. Importantly, evaluation of BCL11B KO signature in patients with metastatic melanoma treated with check point inhibitors, show a more favorable response and survival in the patients with enriched BCL11B KO TIL signature. Thus these results indicate that BCL11B constitutes a promising target for therapeutic intervention in cancer cell therapies to sustain stemness, cytolytic activity and reduce exhaustion. Citation Format: Dorina Avram, Timothy Shaw, Shari Pilon-Thomas, Leonardo Silvane, Tomas Zelenka. Program and epigenetic control of stemness and exhaustion of tumor infiltrating CD8+ T lymphocyte [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 LB358.

Abstract 3965: A cytolytic effector CD8+ T cell response is associated with remission in adult T-cell leukemia/lymphoma

Abstract Introduction: Adult T-cell leukemia/lymphoma (ATLL) is a rare blood cancer that develops in 3-5% of human T-lymphotropic virus-1 (HTLV1) carriers when the combination of viral oncoproteins and somatic mutations lead to malignant transformation of HTLV1 infected CD4+ T cells. ATLL has the worst overall survival among peripheral T cell lymphomas and remains a fatal disease despite efforts to improve outcomes over the last 35 years. First-line combination chemotherapy rarely achieves a durable response and two immune-modulating treatments (α-CCR4 and α-PD-1 monoclonal antibodies) failed in clinical trials. These findings highlight an urgent need to improve our understanding of the functional state of host immunity in ATLL patients. A host immune response against HTLV1 is pivotal in preventing ATLL development. Malignant ATLL cells can escape immune surveillance by preventing antigen presentation and engaging immune checkpoints. The prospect of an ATLL clone inducing systemic suppression was suggested in the literature but has not been directly examined. Furthermore, HTLV1-specific CD8+ cytotoxic T lymphocytes (CTLs) play an important role during viral latency, yet it remains unknown if they play a clinically relevant role during ATLL treatment. Methodology: In this work, we hypothesized that malignant ATLL cells will exhibit a suppressive immune phenotype and that effective therapeutic interventions will augment anti-ATLL CTLs to promote durable remission. We implemented an immune profiling approach to analyze PBMC samples from ATLL patients. Specifically, we developed a powerful 30-marker spectral flow panel to discriminate malignant ATLL cells from non-transformed lymphocytes (T, B, and NK cells) and monitor the expression of key transcription factors and markers associated with proliferation, cytolysis, and exhaustion. We analyzed diagnostic samples from the Montefiore-Einstein ATLL Biobank and samples collected during a phase 2 clinical trial aimed to assess the efficacy of a promising Belinostat/Zidovudine/Interferon-α combination therapy against ATLL (NCT02737046). Results: Our findings reveal that malignant ATLL cells exhibit an immune phenotype associated with robust immunosuppression and yet distinct from other suppressive immune cells (i.e., regulatory T cells). Additionally, we discovered that ATLL patient samples contained a unique population of phenotypically exhausted CD8+ T cells, the proportion of which was drastically reduced in patients under remission. Remarkably, a decrease in this exhausted subset correlated with the expansion of highly cytolytic CD8+ CTLs. Conclusion: Altogether, our findings suggest that ATLL cells may drive CD8+ CTLs into exhaustion to achieve immune evasion and that a robust anti-ATLL CTL response actively contributes to a remission state. Citation Format: Erik Guillen, Eric Liu, Yanhua Wang, Aditi Shastri, Alejandro Sica, Amit Verma, Xingxing Zhang, Juan Carlos Ramos, Hilda Ye, Gregoire Lauvau. A cytolytic effector CD8+ T cell response is associated with remission in adult T-cell leukemia/lymphoma [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 3965.

Downregulation of Hypoxia Inducible Factor-1α in Primary Human Natural Killer Cells Using Small Interfering RNA Delivery with ExPERT ATx by MaxCyte.

Natural killer (NK) cells are innate cytokine-producing and cytolytic effector lymphocytes. Their function is responsive to environmental factors, e.g., hypoxia, a frequent feature of inflamed tissues. Such responses require that the NK cells up-regulate HIF-1α (hypoxia inducible factor-1α), the major mediator of cellular responses to hypoxia that affects cell survival as well as immune responses. Thus, a major approach to the study of NK cell effector function under hypoxic conditions involves the ability to regulate HIF-1α levels in primary human NK cells. One difficulty with this approach, however, is that NK cells are difficult-to-transfect cells and common transfection methods, including electroporation or lipofection, suffer from variable transfection efficiency and cell viability. Moreover, the detection of HIF-1α is technically challenging because of the rapid degradation of the protein under normoxic conditions. Here, using the commercially available ExPERT ATx by MaxCyte, we report a workflow for the reliable delivery of small interfering RNA (siRNA) for targeting HIF-1α expression in primary human NK cells. We further provide a protocol for the detection of HIF-1α by immunoblot analysis demonstrating its efficient downregulation by siRNA. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Isolation of natural killer cells from human peripheral blood mononuclear cells Basic Protocol 2: Delivery of non-coding small interfering RNA and HIF-1α targeting siRNA into natural killer cells using ExPERT ATx Basic Protocol 3: Assessing the downregulation of HIF-1α protein using immunoblot analysis Support Protocol 1: Exemplary assessment of transfection efficiency using fluorescently labeled non-targeting siRNA Support Protocol 2: Exemplary assessment of NK cell viability 20 hr post-transfection Support Protocol 3: Exemplary assessment of HIF-1α knockdown using immunoblot analysis.

Therapeutic application of human type 2 innate lymphoid cells via induction of granzyme B-mediated tumor cell death

The therapeutic potential for human type 2 innate lymphoid cells (ILC2s) has been underexplored. Although not observed in mouse ILC2s, we found that human ILC2s secrete granzyme B (GZMB) and directly lyse tumor cells by inducing pyroptosis and/or apoptosis, which is governed by a DNAM-1-CD112/CD155 interaction that inactivates the negative regulator FOXO1. Over time, the high surface density expression of CD155 in acute myeloid leukemia cells impairs the expression of DNAM-1 and GZMB, thus allowing for immune evasion. We describe a reliable platform capable of up to 2,000-fold expansion of human ILC2s within 4weeks, whose molecular and cellular ILC2 profiles were validated by single-cell RNA sequencing. In both leukemia and solid tumor models, exogenously administered expanded human ILC2s show significant antitumor effects invivo. Collectively, we demonstrate previously unreported properties of human ILC2s and identify this innate immune cell subset as a member of the cytolytic immune effector cell family.

Enhanced cytotoxic activity of natural killer cells from increased calcium influx induced by electrical stimulation.

Natural killer (NK) cells play a crucial role in immunosurveillance independent of antigen presentation, which is regulated by signal balance via activating and inhibitory receptors. The anti-tumor activity of NK cells is largely dependent on signaling from target recognition to cytolytic degranulation; however, the underlying mechanism remains unclear, and NK cell cytotoxicity is readily impaired by tumor cells. Understanding the activation mechanism is necessary to overcome the immune evasion mechanism, which remains an obstacle in immunotherapy. Because calcium ions are important activators of NK cells, we hypothesized that electrical stimulation could induce changes in intracellular Ca2+ levels, thereby improving the functional potential of NK cells. In this study, we designed an electrical stimulation system and observed a correlation between elevated Ca2+ flux induced by electrical stimulation and NK cell activation. Breast cancer MCF-7 cells co-cultured with electrically stimulated KHYG-1 cells showed a 1.27-fold (0.5 V/cm) and 1.55-fold (1.0 V/cm) higher cytotoxicity, respectively. Electrically stimulated KHYG-1 cells exhibited a minor increase in Ca2+ level (1.31-fold (0.5 V/cm) and 1.11-fold (1.0 V/cm) higher), which also led to increased gene expression of granzyme B (GZMB) by 1.36-fold (0.5 V/cm) and 1.58-fold (1.0 V/cm) by activating Ca2+-dependent nuclear factor of activated T cell 1 (NFAT1). In addition, chelating Ca2+ influx with 5 μM BAPTA-AM suppressed the gene expression of Ca2+ signaling and lytic granule (granzyme B) proteins by neutralizing the effects of electrical stimulation. This study suggests a promising immunotherapeutic approach without genetic modifications and elucidates the correlation between cytolytic effector function and intracellular Ca2+ levels in electrically stimulated NK cells.

Tyrosine Kinase Inhibition Activates Intratumoral γδ T Cells in Gastrointestinal Stromal Tumor.

γδ T cells are a rare but potent subset of T cells with pleiotropic functions. They commonly reside within tumors but the response of γδ T cells to tyrosine kinase inhibition is unknown. To address this, we studied a genetically engineered mouse model of gastrointestinal stromal tumor (GIST) driven by oncogenic Kit signaling that responds to the Kit inhibitor imatinib. At baseline, γδ T cells were antitumoral, as blockade of either γδ T-cell receptor or IL17A increased tumor weight and decreased antitumor immunity. However, imatinib therapy further stimulated intratumoral γδ T cells, as determined by flow cytometry and single-cell RNA sequencing (scRNA-seq). Imatinib expanded a highly activated γδ T-cell subset with increased IL17A production and higher expression of immune checkpoints and cytolytic effector molecules. Consistent with the mouse model, γδ T cells produced IL17A in fresh human GIST specimens, and imatinib treatment increased γδ T-cell gene signatures, as measured by bulk tumor RNA-seq. Furthermore, tumor γδ T cells correlated with survival in patients with GIST. Our findings highlight the interplay between tumor cell oncogene signaling and antitumor immune responses and identify γδ T cells as targets for immunotherapy in GIST.

Donor-derived regulatory dendritic cell infusion modulates effector CD8+ T cell and NK cell responses after liver transplantation.

Immune cell-based therapies are promising strategies to facilitate immunosuppression withdrawal after organ transplantation. Regulatory dendritic cells (DCreg) are innate immune cells that down-regulate alloimmune responses in preclinical models. Here, we performed clinical monitoring and comprehensive assessment of peripheral and allograft tissue immune cell populations in DCreg-infused live-donor liver transplant (LDLT) recipients up to 12 months (M) after transplant. Thirteen patients were given a single infusion of donor-derived DCreg 1 week before transplant (STUDY) and were compared with 40 propensity-matched standard-of-care (SOC) patients. Donor-derived DCreg infusion was well tolerated in all STUDY patients. There were no differences in postoperative complications or biopsy-confirmed acute rejection compared with SOC patients up to 12M. DCreg administration was associated with lower frequencies of effector T-bet+Eomes+CD8+ T cells and CD16bright natural killer (NK) cells and an increase in putative tolerogenic CD141+CD163+ DCs compared with SOC at 12M. Antidonor proliferative capacity of interferon-γ+ (IFN-γ+) CD4+ and CD8+ T cells was lower compared with antithird party responses in STUDY participants, but not in SOC patients, at 12M. In addition, lower circulating concentrations of interleukin-12p40 (IL-12p40), IFN-γ, and CXCL10 were detected in STUDY participants compared with SOC patients at 12M. Analysis of 12M allograft biopsies revealed lower frequencies of graft-infiltrating CD8+ T cells, as well as attenuation of cytolytic TH1 effector genes and pathways among intragraft CD8+ T cells and NK cells, in DCreg-infused patients. These reductions may be conducive to reduced dependence on immunosuppressive drug therapy or immunosuppression withdrawal.

Enhanced IL-17 Producing and Maintained Cytolytic Effector Functions of Gut Mucosal CD161+CD8+ T Cells in SIV-Infected Rhesus Macaques.

Previous studies have indicated that the loss of CD161-expressing CD4+ Th17 cells is linked to the progression of chronic HIV. These cells are significantly depleted in peripheral blood and gut mucosa of HIV-infected individuals, contributing to inflammation and disruption of the gut barrier. However, the impact of HIV infection on CD161-expressing CD8+ T cells remain unclear. Here, we examined the functions of peripheral blood and mucosal CD161+CD8+ T cells in the macaque model of HIV infection. In contrast to the significant loss of CD161+CD4+ T cells, CD161+CD8+ T cell frequencies were maintained in blood and gut during chronic SIV infection. Furthermore, gut CD161+CD8+ T cells displayed greater IL-17 production and maintained Th1-type and cytolytic functions, contrary to impaired IL-17 and granzyme-B production in CD161+CD4+ T cells of SIV-infected macaques. These results suggest that augmented Th17-type effector functions of CD161+CD8+ T cells during SIV infection is a likely mechanism to compensate for the sustained loss of gut mucosal Th17 cells. Targeting the cytokine and cytolytic effector functions of CD161+CD8+ T cells in the preclinical setting of chronic SIV infection with antiretroviral therapy has implications in the restoration of gut barrier disruption in persons with HIV infection.

Tandem bispecific CD123/CLL-1 CAR-T cells exhibit specific cytolytic effector functions against human acute myeloid leukaemia.

The treatment of refractory and recurrent acute myeloid leukaemia (AML) is still a challenge with poor response rates and short survival times. In an attempt to solve this problem, we constructed a tandem bispecific chimeric antigen receptor (CAR) targeting CD123 and C-type lectin-like molecule 1 (CLL-1), two different AML antigens, and verified its cytotoxic effects in vitro. We established and cultured K562 cell lines expressing both CD123 and CLL1 antigens. Single-target CAR-T cells specific to CD123 and CLL1 were engineered, alongside tandem CD123/CLL1 bispecific CAR-T cells. Flow cytometry was used to determine cell phenotypes, transfection efficiencies, cytokine release, and CAR-T-cell proliferation, and an lactate dehydrogenase assay was used to detect the cytotoxicity of CD123/CLL-1 bispecific tandem CAR-T cells in vitro. Two types of tandem CAR-T cells exhibited significant killing effects on CLL-1 + CD123+ leukaemia cell lines and primary AML tumour cells. The killing efficiency of tandem CAR-T cells in the case of single antigen expression is comparable to that of single target CAR-T cells. When faced with dual target tumour cells, dual target CAR-T cells significantly surpass single target CAR-T cells. CD123/CLL-1 CAR-T cells in tandem targeted and killed CD123- and CLL-1-positive leukaemia cell lines and released a large number of cytokines. CD123/CLL-1 CAR-T cells in tandem can simultaneously target CD123 and CLL-1 on AML cells, demonstrating a significant ability to kill single antigens and multi-target tumour cells. This suggests that CD123/CLL-1 CAR-T cells exhibit significant advantages in the expression of multiple antigens in a wide range of target cells, which may help overcome the challenges posed by tumour heterogeneity and evasion mechanisms.

Reshaping the anti-tumor CD4 T-cell repertoire contributes to oncolytic virus therapeutic efficacy in malignant glioma

Abstract Malignant gliomas are deadly brain tumors with no cure. We engineered herpes simplex virus (HSV)-1 and developed oncolytic HSV (oHSV) to treat brain tumors, given its potential to selectively kill tumor cells while sparing normal brain cells, and to boost anti-tumor immunity. The therapy shows great promise based on our Phase I trial results. However, the precise mechanisms for its enhanced anti-tumor immune responses remain poorly understood. Using an oHSV secreting murine IL-12 (M002), murine intracranial glioma models and adoptive transfer approaches, we observed that M002 treatment induced unique CD4 +T-cell populations to acquire cytolytic effector phenotypes, promoting anti-glioma responses in an MHCII-dependent manner. Notably, single-cell RNA sequencing and T-cell receptor (TCR) repertoire analysis revealed that M002 treatment shifted the TCR dominance while reducing the clonal diversity. These results suggest that the capacity of oncolytic virus therapy to reshape the anti-tumor CD4 +T-cell repertoire contributes to its improved efficacy. Insights obtained from this study can facilitate the development of better therapeutic strategies for brain tumor patients. Supported by DoD W81XH-18-1-0315 and UAB Faculty Start-up Funds (to JWL)

Non-fatal outcomes of COVID-19 disease in children with solid organ transplants associates with down-regulation of senescent pathways

Abstract Objective: To study the immune landscape during acute infection (AI) & COVID-19 recovery in children with solid organ transplants (SOTs). Method: Blood collected between Nov 2020 – June 2022 from pediatric SOT recipients 1–14-days after a positive PCR for SARS-CoV-2 (AI), & 15–60-days after a positive PCR (convalescence), for Ficoll of PBMC. Cryopreserved PBMC taken from pediatric SOT recipients before 2019 used as non-infected controls (ctrls). PBMCs stimulated with 15-mer peptides from spike protein & co-stimulation with anti-CD49d & anti-CD28. Immunophenotyping by mass cytometry. Data analyzed using the Astrolabe Cytometry Platform, which follows a standardized pipeline for population identification & statistics & visualized using the t-SNE dimensionality reduction method. Disease severity stratified using WHO criteria. Subjects unvaccinated against COVID-19. Results: 38 children included: median age & time from transplant (TX) at infection: 5.5 (2.1–15.1) & 3.3 (0.2–14.7)-years for AI (n=10); 2.4 (0.6–15.6) & 0.5 (0.2–11.2)-years for ctrls (n=20); 6.7 (1.0–12.9) & 4.3 (0.2–9.7)-years for convalescence (n=8). NK & CD4 +T cell (EM, Th 2) frequency increased during AI {p<0.05}. CD57 expression low in T cells with EM phenotype, NKT, & gdT cells in AI vs. ctrls (p<0.05) & in NK cells in severe disease (p<0.05). CD161 expression high in CD4 +T cell (CM, Th1) in convalescence vs. ctrls{ p=0.04}. Conclusion: contraction in NK cells is not a feature of COVID-19 disease in pediatric SOT & global characteristics of NK, NKT & T cell compartments not compatible with senescence. Upregulation of cytolytic effectors in AI. Above a plausible mechanism for low mortality from COVID-19 disease in this patient population.

Boron Derivatives Inhibit the Proliferation of Breast Cancer Cells and Affect Tumor-Specific T Cell Activity In Vitro by Distinct Mechanisms.

Breast cancer is the most frequently diagnosed cancer among women worldwide. Despite the initial clinical response obtained with the widely used conventional chemotherapy, an improved prognosis for breast cancer patients has been missing in the clinic because of the high toxicity to normal cells, induction of drug resistance, and the potential immunosuppressive effects of these agents. Therefore, we aimed to investigate the potential anti-carcinogenic effect of some boron derivatives (sodium pentaborate pentahydrate (SPP) and sodium perborate tetrahydrate (SPT)), which showed a promising effect on some types of cancers in the literature, on breast cancer cell lines, as well as immuno-oncological side effects on tumor-specific T cell activity. These findings suggest that both SPP and SPT suppressed proliferation and induced apoptosis in MCF7 and MDA-MB-231 cancer cell lines through downregulation of the monopolar spindle-one-binder (MOB1) protein. On the other hand, these molecules increased the expression of PD-L1 protein through their effect on the phosphorylation level of Yes-associated protein (Phospho-YAP (Ser127). In addition, they reduced the concentrations of pro-inflammatory cytokines such as IFN-γ and cytolytic effector cytokines such as sFasL, perforin, granzyme A, Granzyme B, and granulysin and increased the expression of PD-1 surface protein in activated T cells. In conclusion, SPP, SPT, and their combination could have growth inhibitory (antiproliferative) effects and could be a potential treatment for breast cancer. However, their stimulatory effects on the PD-1/PD-L1 signaling pathway and their effects on cytokines could ultimately account for the observed repression of the charging of specifically activated effector T cells against breast cancer cells.

Exhausted intratumoral Vδ2− γδ T cells in human kidney cancer retain effector function

Gamma delta (γδ) T cells reside within human tissues including tumors, but their function in mediating antitumor responses to immune checkpoint inhibition is unknown. Here we show that kidney cancers are infiltrated by Vδ2− γδ T cells, with equivalent representation of Vδ1+ and Vδ1− cells, that are distinct from γδ T cells found in normal human tissues. These tumor-resident Vδ2− T cells can express the transcriptional program of exhausted αβ CD8+ T cells as well as canonical markers of terminal T-cell exhaustion including PD-1, TIGIT and TIM-3. Although Vδ2− γδ T cells have reduced IL-2 production, they retain expression of cytolytic effector molecules and co-stimulatory receptors such as 4-1BB. Exhausted Vδ2− γδ T cells are composed of three distinct populations that lack TCF7, are clonally expanded and express cytotoxic molecules and multiple Vδ2− T-cell receptors. Human tumor-derived Vδ2− γδ T cells maintain cytotoxic function and pro-inflammatory cytokine secretion in vitro. The transcriptional program of Vδ2− T cells in pretreatment tumor biopsies was used to predict subsequent clinical responses to PD-1 blockade in patients with cancer. Thus, Vδ2− γδ T cells within the tumor microenvironment can contribute to antitumor efficacy.