Expression Of Cytotoxic Molecules Research Articles

PD-1 knockout on cytotoxic primary murine CD8+ T cells improves their motility in retrovirus infected mice.

Cytotoxic T lymphocyte (CTL) motility is an important feature of effective CTL responses and is impaired when CTLs become exhausted, e.g. during chronic retroviral infections. A prominent T cell exhaustion marker is programmed cell death protein 1 (PD-1) and antibodies against the interaction of PD-1 and PD-ligand 1 (PD-L1) are known to improve CTL functions. However, antibody blockade affects all PD-1/PD-L1-expressing cell types, thus, the observed effects cannot be attributed selectively to CTLs. To overcome this problem, we performed CRISPR/Cas9 based knockout of the PD-1 coding gene PDCD1 in naïve Friend Retrovirus (FV)-specific CTLs. We transferred 1,000 of these cells into mice where they proliferated upon FV-infection. Using intravital two-photon microscopy we visualized CTL motility in the bone marrow and evaluated cytotoxic molecule expression by flow cytometry. Knockout of PDCD1 improved the CTL motility at 14 days post infection and enhanced the expression of cytotoxicity markers. Our data show the potential of genetic tuning of naive antiviral CTLs and might be relevant for future designs of improved T cell-mediated therapies.

Radiofrequency radiation reshapes tumor immune microenvironment into antitumor phenotype in pulmonary metastatic melanoma by inducing active transformation of tumor-infiltrating CD8+ T and NK cells.

Immunosuppression by the tumor microenvironment is a pivotal factor contributing to tumor progression and immunotherapy resistance. Priming the tumor immune microenvironment (TIME) has emerged as a promising strategy for improving the efficacy of cancer immunotherapy. In this study we investigated the effects of noninvasive radiofrequency radiation (RFR) exposure on tumor progression and TIME phenotype, as well as the antitumor potential of PD-1 blockage in a model of pulmonary metastatic melanoma (PMM). Mouse model of PMM was established by tail vein injection of B16F10 cells. From day 3 after injection, the mice were exposed to RFR at an average specific absorption rate of 9.7 W/kg for 1 h per day for 14 days. After RFR exposure, lung tissues were harvested and RNAs were extracted for transcriptome sequencing; PMM-infiltrating immune cells were isolated for single-cell RNA-seq analysis. We showed that RFR exposure significantly impeded PMM progression accompanied by remodeled TIME of PMM via altering the proportion and transcription profile of tumor-infiltrating immune cells. RFR exposure increased the activation and cytotoxicity signatures of tumor-infiltrating CD8+ T cells, particularly in the early activation subset with upregulated genes associated with T cell cytotoxicity. The PD-1 checkpoint pathway was upregulated by RFR exposure in CD8+ T cells. RFR exposure also augmented NK cell subsets with increased cytotoxic characteristics in PMM. RFR exposure enhanced the effector function of tumor-infiltrating CD8+ T cells and NK cells, evidenced by increased expression of cytotoxic molecules. RFR-induced inhibition of PMM growth was mediated by RFR-activated CD8+ T cells and NK cells. We conclude that noninvasive RFR exposure induces antitumor remodeling of the TIME, leading to inhibition of tumor progression, which provides a promising novel strategy for TIME priming and potential combination with cancer immunotherapy.

Abstract 1541: Heterogeneity of the hormone receptor-positive breast tumor immune microenvironment according to patient’s body mass index

Abstract Background: Obesity is a risk factor for postmenopausal hormone receptor-positive (HR+) breast cancer (BC) and is associated with poorer outcomes. “Obesity-paradox”, a phenomenon where obesity (BMI ≥ 30) is associated with better outcomes in patients treated with immune checkpoint inhibitors (ICI), has been observed in several cancer types. It is however under-explored in BC, especially HR+ BC. Emerging data from recent trials (KEYNOTE-756 and CheckMate 7FL) have shown the potential benefits of ICI for treating early HR+ BC. This prompted the need for better insights into the biological link between obesity and HR+ BC, particularly its tumor immune microenvironment (TIME). Patients & Methods: A monocentric cohort of 33 patients (11 lean, 11 overweight, 11 obese) with early HR+ BC was selected for the study, whose tumor tissues were collected and subjected to snRNA-seq. Unsupervised clustering and cluster annotation were performed on the processed data leading to identification of cell types and subtypes. We then performed differential gene expression (DGEA) and gene set enrichment analyses (GSEA) according to BMI category for each of the immune cell types. Results: We identified a total of 76,773 immune cells belonging to six major cell types, namely B/plasma cell, dendritic cell (DC), mast cell, monocyte/macrophage (mono/macro), T cell, and natural killer (NK) cell. Their proportions varied between patients, however immune cellular composition was not associated with BMI. DGEA and GSEA revealed highly cell type-specific obesity-associated differences in the expression profile of immune cells. Notably, an enrichment of B cell-mediated immune activities, substantiated by the upregulation of Ig genes, was observed in B cells and plasma cells. This was however coupled with an overexpression of the checkpoint BTLA in B cells. CD8+ and CD4+ T cells showed a lower level of activation (higher LEF1, TCF7, lower ANXA1, IL4R), and NK cells a decreased cytokine production (CD96, CD226) and conflicting differential expression of cytotoxic molecules (lower NKG7, higher granzymes). Checkpoint genes such as PDCD1, CTLA4, TIGIT, LAG3, HAVCR2 did not show significant changes in their expression in T/NK cells. Mast cells displayed a downregulation of antigen presenting genes (CD74, HLA-A/B/E). DC and mono/macro populations also exhibited both up- and down-regulation of genes involved in different immune pathways. Conclusion: Our current data suggested that obesity was associated with multi-directional changes in the immune activities, possibly implying an unresolved inflammation in the HR+ BC tissue. Further investigation incorporating other cell types and their interaction with immune cells in both tumor and matched normal mammary tissues is warranted and on-going, which could provide more understanding of HR+ breast TIME and lead to speculation on therapeutic implications. Citation Format: Ha-Linh Nguyen, Tatjana Geukens, Maxim De Schepper, Karen Van Baelen, Marion Maetens, Gitte Zels, Amena Mahdami, Edoardo Isnaldi, Sigrid Hatse, Joke Verbeke, Christophe Matthys, Bernard Thienpont, Evy Vanderheyden, Thomas Van Brussel, Rogier Schepers, Gino Philips, Bram Boeckx, Diether Lambrechts, Giuseppe Floris, François Richard, Christine Desmedt. Heterogeneity of the hormone receptor-positive breast tumor immune microenvironment according to patient’s body mass index [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 1541.

Hyperactivation and enhanced cytotoxicity of reduced CD8+ gamma delta T cells in the intestine of patients with Crohn’s disease correlates with disease activity

Background and aimsWe aimed to investigate the immune characteristics of intestinal CD8+ gamma delta T (CD8+ γδ T) cells in Crohn’s disease (CD) and their correlation with disease activity.MethodsThe study cohorts included 21 CD patients and 21 healthy individuals. CD8+ γδ T cells were isolated from human ileal mucosa for detection by flow cytometry. The activation or inhibition status of cells was detected by detecting the expression of activation marker HLA-DR and the immunosuppressive molecule PD-1 on cells. The cytotoxicity of cells was assessed by detecting the expression of cytotoxic molecules (Perforin, Granzyme B, and TRAIL) in cells. Ratios of investigated cells were calculated as prediction factors by receiver operating characteristic curve (ROC) analysis.ResultsThe study revealed a reduction in intestinal CD8+ γδT cells among active CD patients, with a more pronounced reduction observed in moderately active patients compared to mildly active patients. Moreover, active CD patients exhibited heightened activation levels in their intestinal CD8+ γδT cells, whereas the activation was comparatively weakened in moderately active patients compared with mildly active patients. Additionally, the cytotoxicity of intestinal CD8+ γδT cells was enhanced solely in mildly active patients, while it was impaired in moderately active patients compared with mildly active patients. Furthermore, HLA-DR+ CD8+ γδT cell ratio, CD8+ γδT ratio, and CD8+ γδT count were identified as indicators in the diagnosis of active CD. Meanwhile, the ratios of Granzyme B+ CD8+ γδT cell and Perforin+ CD8+ γδT cell were identified as indicators that distinguish mildly moderately active CD cases.ConclusionsIntestinal CD8+ γδT was reduced in active CD patients, but their activation and cytotoxicity were enhanced. However, with increased disease activity, intestinal CD8+ γδ T cells became dysfunctional. CD-specific perturbations observed in various phenotypic markers in CD8+ γδ T cells can be used as indicators to assist in diagnosing CD patients.

Type-1 regulatory T cells are critical for curative immunotherapy outcomes

Abstract IL-10 producing CD4 +type-1 regulatory T cells (Tr1) mediate immune tolerance during chronic infection, autoimmunity, and transplantation. We previously demonstrated that eomesodermin (Eomes) promotes Tr1 cell (Eomes +IL-10 +) development after allogenic bone marrow transplantation (alloBMT). Here we define the differentiation trajectory of Tr1 cells and the functional states therein. Eomes −IL-10 −, Eomes +IL-10 −and Eomes +IL-10 +subsets (defined by mCherry and GFP expression respectively) were FACS sorted after alloBMT and transferred into secondary recipients. Eomes +IL-10 +T cells were stable in phenotype after transfer while the Eomes +IL-10 −T cell subset differentiated into Eomes +IL-10 +Tr1 cells. Tr1 differentiation was associated with progressive enrichment for cytotoxicity (Perforin, Nkg7, Granzyme K, Tnfrsf9), immune regulatory (IR) (Tim-3, Lag3, Tox, Nr4a2) and chemokine (Ccl3, Ccl4, Ccl5) RNA expression. Equivalent IR, cytotoxic and cytokine/chemokine expression was confirmed at a protein level. The conditional deletion of Eomes in CD4 T cells prevented Tr1 differentiation and resulted in impaired cytotoxicity in vivo, the accumulation of donor CD11c +dendritic cells, mixed donor chimerism and leukemia relapse, consistent with a critical role for this lineage in tolerance, engraftment and graft-versus-leukemia effects. The deletion of Eomes from CD19-targeted chimeric antigen receptor (CAR) T cells, reduced cytotoxic molecule expression (perforin, granzyme A/B) in CD4 CAR T cells and resulted in immune escape due to CD19 antigen loss in leukemia cells. In sum, Tr1 cells mediate critical Eomes-dependent cytotoxic and regulatory function that are critical for curative immunotherapy outcomes.

Blocking activation of CD4−CD8− T cells modulates their cytotoxic potential and decreases the expression of inflammatory and chemotactic receptors

CD4−CD8− (double negative – DN) T cells represent a small fraction of circulating T lymphocytes but are a major source of pro-inflammatory cytokines in patients with infectious diseases, including chronic Chagas cardiomyopathy (CCC), one of the deadliest cardiopathies known. Chagas disease is caused by an infection with the protozoan parasite Trypanosoma cruzi and can lead to either an asymptomatic form or a high-mortality cardiac disease. While circulating DN T cells represent a major inflammatory cytokine-expressing cell population in Chagas disease, their potential to be recruited to the heart and to perform cytotoxicity has not been determined. Our previous studies showed that blocking DN T cell activation decreases the expression of IFN-gamma, a cytokine involved in the severity of CCC. Here, studying a well-characterized cohort of Chagas patients with CCC or the asymptomatic form of Chagas disease (indeterminate form, IND), we evaluated the expression of cytotoxic molecules, cytokine and chemokine receptors in γδ+ and αβ+ DN T cells by multiparameter flow cytometry, and investigated whether blocking the activation of DN T cells influences the expression of these molecules. We observed that DN T cells from CCC display a higher expression of granzyme A, perforin, inflammatory molecules, and inflammatory chemokine receptors than cells from IND. Messenger RNA coding for these molecules is also upregulated in the heart of CCC patients. Importantly, blocking the activation of DN T cells from CCC modulates their cytotoxic potential and the expression of inflammatory and of chemokine receptors, suggesting that targeting DN T cell activation may be a valid strategy to reduce recruitment to the heart, inflammation, cytotoxicity and, thereby diminish CCC progression and severity.

Abstract 4688: Comprehensive analysis of natural killer cell-associated markers using MultiOmyxTM immunofluorescence assay

Abstract As a promising alternative platform for cellular immunotherapy, natural killer cells (NK) have recently gained attention as an important type of innate immune regulatory cell. NK cell immunotherapy approaches have been translated into clinical applications, and clinical trials of NK cell infusion in patients with hematological malignancies (HM) and solid tumors have thus far yielded many encouraging clinical results. Understanding the pattern of NK expression and the relationship to different states of NK cells may have direct relevance for immune responses in cancer. Approaches capable of simultaneously detecting NK cells with detailed information on NK differentiation state, however, remain limited. In this study, we used MultiOmyx hyperplexed immunofluorescence (IF) assay to classify and characterize the spatial arrangement of NK cell markers in a pan-cancer cohort including 9 tissue microarrays (TMAs) from breast, head and neck, prostrate, colon, bladder, lung, kidney, ovarian and melanoma indications. The panel includes CD3, CD4, CD8, CD16, CD45, CD56, CD57, CD137, FoxP3, Granzyme B, HLA-E, NKG2A, NKP46 and tumor segmentation marker. The panel enables the detection of NK cells expressing CD56 and/or NKP46 in the 9 different tumor indications. We also studied the expression of activating and inhibiting receptors, such as CD16 and NKG2A, in NK cell population. The active cytotoxic subsets of mature NK cells were evaluated using co-expression of NK cell surface markers with CD57 and the cytotoxic molecule expression in NK cells was assessed using co-expression with Granzyme B. Using proprietary deep-learning-based image analysis, we were able to quantify the densities of these different NK cell population and study the prevalence of these NK cells in different cancer indications included in this study. Many strategies have been developed for exploiting NK-mediated anti-tumor activities. CAR-NK cell therapy and antibodies that directly target NK cell inhibitory receptors such as NKG2A and TIGIT, are currently being evaluated in the clinical trials. The MultiOmyx NK cell panel reported in this study enables the comprehensive profiling of the NK population and can provide greater understanding of NK cell biology during cancer progression. The panel can be further used to explore the efficacy of the NK cell-based immune therapy. Citation Format: Erinn A. Parnell, Jiong Fei, Harry Nunns, Eric Leones, Elaine Yeung, Blair Russell, Flora Sahafi, Qingyan Au. Comprehensive analysis of natural killer cell-associated markers using MultiOmyxTM immunofluorescence assay. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4688.

Differential CD4+ T-Cell Cytokine and Cytotoxic Responses Between Reactivation and Latent Phases of Herpes Zoster Infection.

CD4+ T cells are a critical component of effective immune responses to varicella zoster virus (VZV), but their functional properties during the reactivation acute vs latent phase of infection remain poorly defined. Here we assessed the functional and transcriptomic properties of peripheral blood CD4+ T cells in persons with acute herpes zoster (HZ) compared to those with a prior history of HZ infection using multicolor flow cytometry and RNA sequencing. We found significant differences between the polyfunctionality of VZV-specific total memory, effector memory, and central memory CD4+ T cells in acute vs prior HZ. VZV-specific CD4+ memory T-cell responses in acute HZ reactivation had higher frequencies of IFN-γ and IL-2 producing cells compared to those with prior HZ. In addition, cytotoxic markers were higher in VZV-specific CD4+ T cells than non-VZV-specific cells. Transcriptomic analysis of ex vivo total memory CD4+ T cells from these individuals showed differential regulation of T-cell survival and differentiation pathways, including TCR, cytotoxic T lymphocytes (CTL), T helper, inflammation, and MTOR signaling pathways. These gene signatures correlated with the frequency of IFN-γ and IL-2 producing cells responding to VZV. In summary, VZV-specific CD4+ T cells from acute HZ individuals had unique functional and transcriptomic features, and VZV-specific CD4+ T cells as a group had a higher expression of cytotoxic molecules including Perforin, Granzyme-B, and CD107a.

Selective depletion of polymorphonuclear myeloid derived suppressor cells in tumor beds with near infrared photoimmunotherapy enhances host immune response

ABSTRACT The immune system is recognized as an important factor in regulating the development, progression, and metastasis of cancer. Myeloid-derived suppressor cells (MDSCs) are a major immune-suppressive cell type by interfering with T cell activation, promoting effector T cell apoptosis, and inducing regulatory T cell expansion. Consequently, reducing or eliminating MDSCs has become a goal of some systemic immunotherapies. However, by systemically reducing MDSCs, unwanted side effects can occur. Near-infrared photoimmunotherapy (NIR-PIT) is a newly developed treatment that selectively kills targeted cells without damaging adjacent normal cells. The aim of this study is to evaluate the antitumor efficacy of MDSC-directed NIR-PIT utilizing anti-Ly6G antibodies to specifically destroy polymorphonuclear (PMN)-MDSCs in the tumor microenvironment (TME) in syngeneic mouse models. PMN-MDSCs were selectively eliminated within tumors by Ly6G-targeted NIR-PIT. There was significant tumor growth suppression and prolonged survival in three treated tumor models. In the early phase after NIR-PIT, dendritic cell maturation/activation and CD8+ T cell activation were enhanced in both intratumoral tissues and tumor-draining lymph nodes, and NK cells demonstrated increased expression of cytotoxic molecules. Host immunity remained activated in the TME for at least one week after NIR-PIT. Abscopal effects in bilateral tumor models were observed. Furthermore, the combination of NIR-PIT targeting cancer cells and PMN-MDSCs yielded synergistic effects and demonstrated highly activated host tumor immunity. In conclusion, we demonstrated that selective local PMN-MDSCs depletion by NIR-PIT could be a promising new cancer immunotherapy.

Intraepithelial cytotoxic lymphocytes are associated with a poor prognosis in feline intestinal T-cell lymphoma.

The expression of cytotoxic molecules in feline intestinal T-cell lymphoma cells was examined immunohistochemically using endoscopic samples of 50 cases. Cases included 14 large-cell lymphomas (LCLs) and 36 small-cell lymphomas (SCLs). Most LCL and some SCL exhibited marked erosion and villous atrophy. Clonal T-cell receptor (TCR) gene rearrangement was detected in 10/14 (71%) LCL cases and 33/36 (92%) SCL cases. No clonal immunoglobulin heavy chain (IgH) gene rearrangement was detected. Immunohistochemically, all cases were positive for CD3 and negative for CD79α, CD30, CD56, and Foxp3. LCLs were positive for CD8 in 13/14 cases (93%), T-cell intracellular antigen 1 (TIA1) in 14/14 cases (100%), and granzyme B in 6/14 cases (43%). SCLs were positive for CD8 in 28/36 cases (78%), TIA1 in 33/36 cases (92%), and granzyme B in 2/36 cases (6%). TIA1- and granzyme B-positive neoplastic lymphocytes were predominantly observed in the mucosal epithelium of 10/50 cases (20%) and 6/50 cases (12%), respectively. No significant differences in survival time were found based on cell size or epitheliotropism. However, cases with TIA1+ and/or granzyme B+ neoplastic lymphocytes predominantly in the mucosal epithelium had significantly shorter survival times (P < .05), suggesting that mucosal epithelium infiltration of neoplastic cells with a cytotoxic immunophenotype is a negative prognostic factor. Therefore, intraepithelial cytotoxic lymphocytes may be associated with mucosal injury and impaired intestinal function, leading to a poor prognosis in cats with intestinal T-cell lymphoma.

BSCI-15 INVESTIGATING CD8 T CELL EXHAUSTION STATES WITHIN THE TME AND DRAINING LYMPH NODE OF PRIMARY BRAIN TUMORS AND BRAIN METASTASES

Abstract Brain metastases affect nearly 20% of all cancer patients. Likewise, glioblastoma (GBM) is the most common primary brain cancer in adults and remains universally lethal. Current immunotherapeutic efficacy is hindered by immunosuppression present in the brain tumor microenvironment (TME). T-cells, critical for tumor clearance, take on a functionally exhausted phenotype. Importantly, two exhaustion states, progenitor (Tpe) and terminal (Tte), have been identified in models of chronic infection and cancer. This distinction is particularly relevant, as Tpe can remain responsive to immune checkpoint blockade (ICB), while Tte cannot. To date, the dynamics and characteristics of these exhausted populations in primary tumors and brain metastases remain unclear. Using intracranially implanted murine models of GBM (CT2A) and metastatic melanoma (B16F10), Tpe and Tte were identified by flow cytometry as PD1+SLAMF6+ and PD1+TIM3+, respectively. Functional differences between subsets were evaluated via intracellular staining of IFNγ, TNFα, IL2, CD107a, and Ki67. To determine the role of antigen, we performed adoptive lymphocyte transfers of tumor-specific and non-tumor-specific transgenic T-cells into a TRP2 or OVA overexpressing intracranial CT2A or B16 tumor, respectively. Tte displayed higher cytotoxic molecule expression than Tte, consistent with chronic infection models. Key exhaustion-associated transcription factors were identified in exhaustion subsets, including Tox, Tcf7, T-bet, and Eomes. Tox and Tcf7 expression identified Tpe within tumor-draining lymph nodes, suggesting a potential origin outside of the tumor, and the capacity for rescued function. We observed a decline in the Tpe population over time, with an associated rise in Tte within both tumor types. Notably, the ratio of Tpe to Tte was higher at all time points in B16F10 compared to CT2A. Tte appeared only in tumor-specific T-cells of the TME, further confirming the tumor-antigen dependence of T cell exhaustion. Tpe may arise outside the TME in tumor-specific T-cells. Further study may reveal a means and time window for rescuing T-cell function with ICB for brain tumors.

Targeting inflammatory monocytes by immune-modifying nanoparticles prevents acute kidney allograft rejection

Inflammatory monocytes are a major component of the cellular infiltrate in acutely rejecting human kidney allografts. Since immune-modifying nanoparticles (IMPs) bind to circulating inflammatory monocytes via the specific scavenger receptor MARCO, causing diversion to the spleen and subsequent apoptosis, we investigated the therapeutic potential of negatively charged, 500-nm diameter polystyrene IMPs to prevent kidney allograft rejection. Kidney transplants were performed from BALB/c (H2d) to C57BL/6 (H2b) mice in two groups: controls (allo) and allo mice infused with IMPs. Groups were studied for 14 (acute rejection) or 100 (chronic rejection) days. Allo mice receiving IMPs exhibited superior survival and markedly less acute rejection, with better kidney function, less tubulitis, and diminished inflammatory cell density, cytokine and cytotoxic molecule expression in the allograft and lower titers of donor-specific IgG2c antibody in serum at day 14, as compared to allo mice. Cells isolated from kidneys from allo mice receiving IMPs showed reduced Ly6Chi monocytes, CD11b+ cells and NKT+ cells compared to allo mice. IMPs predominantly bound CD11b+ cells in the bloodstream and CD11b+ and CD11c-B220+ marginal zone B cells in the spleen. In the spleen, IMPs were found predominantly in red pulp, colocalized with MARCO and expression of cleaved caspase-3. At day 100, allo mice receiving IMPs exhibited reduced macrophage M1 responses but were not protected from chronic rejection. IMPs afforded significant protection from acute rejection, inhibiting both innate and adaptive alloimmunity. Thus, our current experimental findings, coupled with our earlier demonstration of IMP-induced protection in kidney ischemia-reperfusion injury, identify IMPs as a potential induction agent in kidney transplantation.

Abstract 4188: CD4+ T cells mediate non-canonical rejection of major histocompatibility class-I deficient pancreatic tumors independently of CD8+ T cells

Abstract Identifying and interrogating novel immune-mediated mechanisms of tumor rejection is a major clinical opportunity. Immune checkpoint blockade (ICB) induces tumor rejection primarily via cytolytic CD8+ T cells, but many patients have primary or acquired resistance to CD8+ T cell immunity. Reduced major histocompatibility complex I (MHC I) expression is a contributing factor to resistance, and pancreatic ductal adenocarcinoma (PDAC) is historically treatment-refractory due to, among other features, low MHC expression and a dearth of T cells in the tumor. Interrogating interventions in the context of the PDAC tumor microenvironment will reveal novel mechanisms regulating sensitivity to immune-mediated destruction. Using a genetically engineered mouse model of PDAC, we previously reported that combination immunotherapy (agonistic anti-CD40 and dual ICB, anti-PD-1/CTLA-4) induced both a CD8+ and a CD4+ T cell response sufficient to mediate tumor rejection and long-lived protection. Here, we utilized CRISPR-Cas9 to disrupt the dominant MHC I (H-2Kb allele) expression in PDAC cell lines, precluding direct antigen presentation to CD8+ T cells via this molecule. Subcutaneous injection of MHC I-deficient tumor clones into wild-type mice revealed normal tumor growth at baseline, and significantly delayed tumor growth kinetics in response to combination immunotherapy (CD40/ICB) in a CD4+ T cell-dependent manner (p &amp;lt; 0.0001 vs. vehicle-treated mice). These findings were observed in parental PDAC clones lacking H-2Kb expression, as well as in an ovalbumin (OVA)-expressing PDAC clone. CD4+ T cells mediated tumor rejection including in OVA-tolerized mice, excluding the role of tumor-neoantigens as a major determinant of response. There was no direct contribution of tumor rejection by CD8+ T cells, despite the generation of an activated, tumor-specific CD8+ T cell response in the tumor site (24.5% vs. 1.98% in vehicle-treated mice, p &amp;lt; 0.003). CD4+ T cells upregulated IFN-γ production (52.3% vs. 11.9% in vehicle-treated mice, p &amp;lt; 0.0001), and host IFN-γ and IFN-γ receptor expression were required for response. No changes were observed in the expression of cytotoxic molecules (Granzyme A or B) by CD4+ T cells after CD40/ICB, and perforin was not required for tumor rejection. Furthermore, depletion of macrophage and myeloid cells or genetic knockout of inducible nitric oxide synthase did not dampen CD4+ T cell immunity against established PDAC tumors. Thus, CD4+ T cells mediated PDAC tumor rejection via non-canonical mechanisms, excluding cytotoxic molecules and re-direction of anti-tumor macrophage effector functions after treatment with anti-CD40/ICB. This study provides critical insight into novel mechanisms of tumor clearance beyond direct CD8+ T cell:tumor cell interactions, and opportunities to exploit CD4 T+ cells as regulators of tumor immunity. Citation Format: Samuel I. Kim, Charu Arora, Ioannis I. Verginadis, Christopher R. Cassella, Nune Markosyan, Constantinos Koumenis, Robert H. Vonderheide, Katelyn T. Byrne. CD4+ T cells mediate non-canonical rejection of major histocompatibility class-I deficient pancreatic tumors independently of CD8+ T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4188.

CD4+ T cells mediate non-canonical rejection of major histocompatibility class-I deficient pancreatic tumors independently of CD8+ T cells

Abstract Cytolytic CD8+ T cells are a major mediator of immune-induced tumor rejection, but many patients have primary or acquired resistance to CD8+ T cell immunity. Reduced major histocompatibility complex I (MHC I) expression contributes to resistance, including treatment-refractory pancreatic ductal adenocarcinoma (PDAC). Interrogating interventions in PDAC will reveal novel mechanisms regulating sensitivity to immunotherapy. Using a genetically engineered mouse model of PDAC, we previously reported that agonistic anti-CD40 and dual immune checkpoint blockade (ICB) induces CD8+ and a CD4+ T cell responses mediating tumor rejection. Here, we utilized CRISPR− Cas9 to disrupt the dominant MHC I (H-2Kb) allele expression in PDAC cell lines, precluding direct antigen presentation to CD8+ T cells. Injection of MHC I-deficient tumor clones revealed normal tumor growth at baseline, and significantly delayed tumor growth in response to CD40/ICB in a CD4+ T cell-dependent manner (p &amp;lt; 0.0001 vs. vehicle-treated mice). There was no direct contribution of tumor rejection by CD8+ T cells, despite the generation of a tumor-specific response (24.5% vs. 1.98% in vehicle-treated mice, p&amp;lt;0.003). CD4+ T cells upregulated IFN-γ production (52.3% vs. 11.9% in vehicle-treated mice, p&amp;lt;0.0001), and host IFN-γ expression was required. No changes were observed in the expression of cytotoxic molecules by CD4+ T cells after CD40/ICB, and depletion of myeloid cells did not dampen treatment efficacy. Thus, CD4+ T cells mediated PDAC rejection via non-canonical mechanisms after treatment with CD40/ICB. This study provides critical insight into novel mediators of tumor clearance, and opportunities to exploit CD4 T+ cells as regulators of tumor immunity. Funded by the Parker Institute for Cancer Immunotherapy.

Overexpression of ascitic interleukin-35 induces CD8+ T cell exhaustion in liver cirrhotic patients with spontaneous bacterial peritonitis

Interleukin (IL) -35 induces immunotolerance by suppression of CD8+ T cells during chronic infections and cancers. In the present study, we amined to investigate the role of IL-35-mediated regulation of CD8+ T cells in patients with liver cirrhosis. Seventy-one patients with liver cirrhosis (46 patients with untainted ascites and 25 patients with spontaneous bacterial peritonitis [SBP]) and 22 controls were enrolled. Plasma and ascitic IL-35 levels were measured using ELISA. Peripheral and ascitic CD4+ and CD8+ T cells were purified to investigate their functional phenotypes. IL-35-stimulated CD8+ T cells were cultured with HepG2 cells in direct and indirect contact systems. Lactate dehydrogenase expression and cytokine secretion were measured to determine the cytotoxicity of CD8+ T cells. Plasma IL-35 was elevated in patients with liver cirrhosis, and ascitic IL-35 levels were higher in the SBP group than in the untainted ascites group. No significant differences in transcription factor expression or cytokine production in peripheral and ascitic CD4+ T cells were observed among groups. In the SBP group, ascitic CD8+ T cells expressed decreased cytotoxic molecules, along with the reduced secretion of interferon-γ and tumor necrosis factor-α when compared with the untainted ascites group. IL-35 stimulation suppressed ascitic CD8+ T cell cytotoxicity and cytokine production in both direct and indirect contact culture systems. This process was accompanied by decreased cytotoxic molecule expression and increased immune-checkpoint molecules in ascitic CD8+ T cells. The present findings revealed that overexpression of ascitic IL-35 dampened the cytotoxicity of CD8+ T cells in liver cirrhotic patients with SBP.

The Pathologic and Genetic Characteristics of Extranodal NK/T-Cell Lymphoma.

Extranodal NK/T-cell lymphoma is a neoplasm of NK cells or cytotoxic T cells presenting in extranodal sites, most often in the nasal cavity. The typical immunophenotypes are cCD3+, sCD3−, CD4−, CD5−, CD8−, CD16−, and CD56+ with the expression of cytotoxic molecules. Tumor subsets express NK cell receptors, CD95/CD95L, CD30, MYC, and PDL1. Virtually all the tumor cells harbor the EBV genome, which plays a key role in lymphomagenesis as an epigenetic driver. EBV-encoded oncoproteins modulate the host-cell epigenetic machinery, reprogramming the viral and host epigenomes using host epigenetic modifiers. NGS analysis revealed the mutational landscape of ENKTL, predominantly involving the JAK–STAT pathway, epigenetic modifications, the RNA helicase family, the RAS/MAP kinase pathway, and tumor suppressors, which indicate an important role of these pathways and this group of genes in the lymphomagenesis of ENKTL. Recently, three molecular subtypes were proposed, the tumor-suppressor/immune-modulator (TSIM), MGA-BRDT (MB), and HDAC9-EP300-ARID1A (HEA) subtypes, and they are well-correlated with the cell of origin, EBV pattern, genomic alterations, and clinical outcomes. A future investigation into the function and interaction of discovered genes would be very helpful for better understanding the molecular pathogenesis of ENKTL and establishing better treatment strategies.

Clinicopathologic and Genetic Features of Primary T-cell Lymphomas of the Central Nervous System: An Analysis of 11 Cases Using Targeted Gene Sequencing.

Primary central nervous system lymphoma (PCNSL) of peripheral T-cell lineage (T-PCNSL) is rare, and its genetic and clinicopathologic features remain unclear. Here, we present 11 cases of T-PCNSL in immunocompetent individuals from a single institute, focusing on their genetic alterations. Seven cases were subject to targeted panel sequencing covering 120 lymphoma-related genes. Nine of the eleven cases were classified as peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), of which one was of γδT-cell lineage. There was one case of anaplastic lymphoma kinase-positive anaplastic large cell lymphoma and another of extranodal natural killer (NK)/T-cell lymphoma (ENKTL) of αβT-cell lineage. The male to female ratio was 7 : 4 and the age ranged from 3 to 75 years (median, 61 y). Most patients presented with neurological deficits (n=10) and showed multifocal lesions (n=9) and deep brain structure involvement (n=9). Tumor cells were mostly small-to-medium, and T-cell monoclonality was detected in all nine evaluated cases. PTCL-NOS was CD4-positive (n=4), CD8-positive (n=3), mixed CD4-positive and CD8-positive (n=1), or CD4/CD8-double-negative (n=1, γδT-cell type). Cytotoxic molecule expression was observed in 4 (67%) of the 6 evaluated cases. Pathogenic alterations were found in 4 patients: one PTCL-NOS case had a frameshift mutation in KMT2C, another PTCL-NOS case harbored a truncating mutation in TET2, and another (γδT-cell-PTCL-NOS) harbored NRAS G12S and JAK3 M511I mutations, and homozygous deletions of CDKN2A and CDKN2B. The ENKTL (αβT-cell lineage) case harbored mutations in genes ARID1B, FAS, TP53, BCOR, KMT2C, POT1, and PRDM1. In conclusion, most of the T-PCNSL were PTCL-NOS, but sporadic cases of other subtypes including γδT-cell lymphoma, anaplastic lymphoma kinase-positive anaplastic large cell lymphoma, and ENKTL were also encountered. Immunophenotypic analysis, clonality test, and targeted gene sequencing along with clinicoradiologic evaluation, may be helpful for establishing the diagnosis of T-PCNSL. Moreover, this study demonstrates genetic alterations with potential diagnostic and therapeutic utility in T-PCNSL.

Gene Expression Analysis of the Bone Marrow Microenvironment Reveals Distinct Immunotypes in Smoldering Multiple Myeloma Associated to Progression to Symptomatic Disease.

BackgroundWe previously reported algorithms based on clinical parameters and plasma cell characteristics to identify patients with smoldering multiple myeloma (SMM) with higher risk of progressing who could benefit from early treatment. In this work, we analyzed differences in the immune bone marrow (BM) microenvironment in SMM to better understand the role of immune surveillance in disease progression and to identify immune biomarkers associated to higher risk of progression.MethodsGene expression analysis of BM cells from 28 patients with SMM, 22 patients with monoclonal gammopathy of undetermined significance (MGUS) and 22 patients with symptomatic MM was performed by using Nanostring Technology.ResultsBM cells in SMM compared to both MGUS and symptomatic MM showed upregulation of genes encoding for key molecules in cytotoxicity. However, some of these cytotoxic molecules positively correlated with inhibitory immune checkpoints, which may impair the effector function of BM cytotoxic cells. Analysis of 28 patients with SMM revealed 4 distinct clusters based on immune composition and activation markers. Patients in cluster 2 showed a significant increase in expression of cytotoxic molecules but also inhibitory immune checkpoints compared to cluster 3, suggesting the presence of cytotoxic cells with an exhausted phenotype. Accordingly, patients in cluster 3 had a significantly longer progression free survival. Finally, individual gene expression analysis showed that higher expression of TNF superfamily members (TNF, TNFAIP3, TNFRSF14) was associated with shorter progression free survival.ConclusionsOur results suggest that exhausted cytotoxic cells are associated to high-risk patients with SMM. Biomarkers overexpressed in patients with this immune gene profile in combination with clinical parameters and PC characterization may be useful to identify SMM patients with higher risk of progression.

IMMU-15. INVESTIGATING CD8 T CELL EXHAUSTION STATES GLIOBLASTOMA

Abstract BACKGROUND Glioblastoma (GBM) is the most common primary brain cancer in adults and remains universally lethal. Median survival remains a bleak 15-17 months from time of diagnosis, and current immunotherapeutic efficacy continues to be hindered by the robust immunosuppression present in the GBM microenvironment. T cells, critical for tumor clearance, are particularly affected, and many take on a functionally exhausted phenotype within the tumor. Importantly, two exhaustion states, progenitor and terminal, have been identified in models of chronic infection and cancer. This distinction is particularly relevant, as progenitor exhausted T cells can respond favorably to immune checkpoint blockade, while terminally exhausted T cells are resistant. To date, the dynamics and characteristics of these exhausted populations in GBM remain unclear. RESULTS In an orthotopic murine model of GBM, progenitor and terminal exhausted CD8 T cells were identified by flow cytometry as PD1+SLAMF6+ and PD1+TIM3+, respectively. Using a time-course approach, we detected progenitor exhaustion by day 8 in the tumor, but not in draining lymph nodes. Additionally, we show that the frequency of progenitor exhaustion is highest during early tumor progression, while terminal exhaustion is the most abundant in more advanced tumors ( &amp;gt;14 days). Functional differences between subsets were evaluated via intracellular staining of IFNγ, TNFα, granzyme B, and Ki67. Terminally exhausted T cells displayed higher cytotoxic molecule expression than progenitor exhausted T cells, similar to what has been documented in melanoma models. CONCLUSIONS Our findings identify T cell exhaustion subsets within GBM that require further investigation and may be relevant to overcome current barriers to immunotherapeutic efficacy.

IFNγ-producing NK cells in adipose tissue are associated with hyperglycemia and insulin resistance in obese women.

Innate lymphoid cells (ILCs) play an important role in the maintenance of immune and metabolic homeostasis in adipose tissue (AT). The crosstalk between AT ILCs and adipocytes and other immune cells coordinates adipocyte differentiation, beiging, glucose metabolism and inflammation. Although the metabolic and homeostatic functions of mouse ILCs have been extensively investigated, little is known about human adipose ILCs and their roles in obesity and insulin resistance (IR). Here we characterized T and NK cell populations in omental AT (OAT) from women (n = 18) with morbid obesity and varying levels of IR and performed an integrated analysis of metabolic parameters and adipose tissue transcriptomics. In OAT, we found a distinct population of CD56-NKp46+EOMES+ NK cells characterized by expression of cytotoxic molecules, pro-inflammatory cytokines, and markers of cell activation. AT IFNγ+ NK cells, but not CD4, CD8 or γδ T cells, were positively associated with glucose levels, glycated hemoglobin (HbA1c) and IR. AT NK cells were linked to a pro-inflammatory gene expression profile in AT and developed an effector phenotype in response to IL-12 and IL-15. Moreover, integrated transcriptomic analysis revealed a potential implication of AT IFNγ+ NK cells in controlling adipose tissue inflammation, remodeling, and lipid metabolism. Our results suggest that a distinct IFNγ-producing NK cell subset is involved in metabolic homeostasis in visceral AT in humans with obesity and may be a potential target for therapy of IR.