Proliferation Of Cytotoxic T Lymphocytes Research Articles

Oxidized Melanoma Antigens Promote Activation and Proliferation of Cytotoxic T-Cell Subpopulations.

Increasing evidence suggests the role of reactive oxygen and nitrogen species (RONS) in regulating antitumor immune effects and immunosuppression. RONS modify biomolecules and induce oxidative post-translational modifications (oxPTM) on proteins that can alarm phagocytes. However, it is unclear if and how protein oxidation by technical means could be a strategy to foster antitumor immunity and therapy. To this end, cold gas plasma technology producing various RONS simultaneously to oxidize the two melanoma-associated antigens MART and PMEL is utilized. Cold plasma-oxidized MART (oxMART) and PMEL (oxPMEL) are heavily decorated with oxPTMs as determined by mass spectrometry. Immunization with oxidized MART or PMEL vaccines prior to challenge with viable melanoma cells correlated with significant changes in cytokine secretion and altered T-cell differentiation of tumor-infiltrated leukocytes (TILs). oxMART promoted the activity of cytotoxic central memory T-cells, while oxPMEL led to increased proliferation of cytotoxic effector T-cells. Similar T-cell results are observed after incubating splenocytes of tumor-bearing mice with B16F10 melanoma cells. This study, for the first time, provides evidence of the importance of oxidative modifications of two melanoma-associated antigens in eliciting anticancer immunity.

Phase 2 randomized study of rintatolimod following FOLFIRINOX in patients with locally advanced pancreatic adenocarcinoma.

TPS4214 Background: The immunosuppressive microenvironment of pancreatic ductal adenocarcinoma (PDAC) is a driver of its lethality and resistance to immunotherapy. Strategies which modulate the immunosuppressive milieu have the potential to improve the anti-tumor response and improve outcomes in patients with PDAC. Rintatolimod is a synthetic double-stranded RNA molecule that activates the toll-like receptor 3 (TLR3) present on dendritic cells, B-cells, natural killer cells and pancreatic epithelial cells. TLR3 stimulation may increase cytotoxic T-cell activity in PDAC through dendritic cell maturation, antigen priming and downstream proliferation of cytotoxic T-cells. Twenty-seven patients were treated with rintatolimod in a single center Named Patient Program at Erasmus University Medical Center in Rotterdam between January 2017 and February 2019. All had locally advanced or metastatic PDAC which had not progressed on FOLFIRINOX (median 8 cycles). Maintenance rintatolimod, administered intravenously twice weekly for up to 18 weeks, was generally well tolerated. The most common toxicities were grade 1-2 myalgia (30%), chills (52%) and fatigue (30%); no toxicities ≥ grade 3 were observed. Progression-free and overall survival (from cycle 1 FOLFIRINOX) were 13 and 19 months. Methods: This is a phase 2 randomized, open-label, multicenter clinical trial. The primary objective is to assess the efficacy of rintatolimod compared to observation in subjects with locally advanced PDAC which has not progressed after FOLFIRINOX. Eligible patients have completed at least 4 months of FOLFIRINOX, have no evidence of progressive disease, have measurable disease by RECIST v1.1, Karnofsky Performance Status ≥80 and have adequate organ function. Subjects with resected PDAC or metastatic disease are not eligible. Subjects are randomized 2:1 to rintatolimod vs. observation. Rintatolimod is administered intravenously twice weekly until disease progression in the experimental arm. Cross-sectional imaging is performed every 8 weeks in both arms. The primary endpoint is progression-free survival, as assessed by the investigator. Secondary endpoints include overall survival, objective response rate, duration of response and safety, as assessed by CTCAE v5.0. Exploratory endpoints include quality of life and changes in immune cell composition and T-cell response in the peripheral blood to characterize the immunomodulatory effects of rintatolimod. The planned sample size is 90 subjects. The final analysis will be performed after 64 events (disease progression or death) have been observed. The study is powered to detect a hazard ratio of 0.47 for median PFS with 80% power and significance level of 5%. Clinical trial information: NCT05494697 .

DC-derived CXCL10 promotes CTL activation to suppress ovarian cancer

This study investigates the role of dendritic cells (DCs), with a focus on their CXCL10 marker gene, in the activation of cytotoxic T lymphocytes (CTLs) within the ovarian cancer microenvironment and its impact on disease progression. Utilizing scRNA-seq data and immune infiltration analysis, we identified a diminished DC presence in ovarian cancer. Gene analysis pinpointed CXCL10 as a key regulator in OV progression via its influence on DCs and CTLs. Prognostic analysis and in vitro experiments substantiated this role. Our findings reveal that DC-derived CXCL10 significantly affects CTL activation and proliferation. Reduced CXCL10 levels hinder CTL cytotoxicity, promoting ovarian cancer cell migration and invasion. Experimental studies using animal models have provided further evidence that the capacity of CTLs to suppress tumor development is significantly diminished when treated with DCs that have low expression of CXCL10. Dendritic cell-derived CXCL10 emerges as a pivotal factor in restraining ovarian cancer growth and metastasis through the activation of cytotoxic T lymphocytes. This study sheds light on the crucial interplay within the ovarian cancer microenvironment, offering potential therapeutic targets for ovarian cancer treatment.

SP94 engineered erythrocyte membrane enhanced the targeted delivery of biomimetic nanosuspension with IDO immunotherapy and chemotherapy in liver cancer

The efficient eradication of tumor cells remains a critical challenge in the realm of liver cancer therapies. The combination of chemotherapy and immunotherapy holds more significant potential for improving treatment efficacy. However, the effectiveness of immunotherapy is mainly impeded by the high activity of indoleamine 2,3-dioxygenase (IDO), which creates an immunosuppressive tumor microenvironment via robust proliferation of immunosuppressive T regulatory cells (Tregs) and inhibition of cytotoxic T lymphocytes (CTLs). Herein, we developed SR-ATO-ASIV@NS, a liver cancer-targeting peptide (SP94) modified RBCM-coated biomimetic nanosuspension. This innovative formulation incorporates the chemotherapeutic agent arsenic trioxide (ATO) and the immunomodulator astragaloside IV (AS-IV) as IDO inhibitor for the combined chemoimmunotherapy of liver cancer. The SR-ATO-ASIV@NS increased the solubility of both ATO and AS-IV and displayed excellent stability and exhibited high drug-loading efficiency, rendering it suitable for efficient dual drug delivery. Furthermore, this biomimetic nanosuspension efficiently evaded immune response and showed specific uptake in liver cancer cells via SP94 receptor-mediated endocytosis. The remarkable pharmacokinetic profile, characterized by prolonged blood circulation, enhanced the in vivo anti-tumor efficacy in H22 tumor bearing mice through the synergistic action of the dual drugs. On one hand, the released ATO resulted in excessive reactive oxygen species (ROS) generation, which stimulated the induction of apoptosis pathways via Bax/Bcl-2 and caspase mechanism. While on the other hand, AS-IV effectively blocked the IDO activity and hinders the production of Tregs within the tumor microenvironment. Consequently, the reduced Tregs population fosters the proliferation of CTLs, alleviating ITM and intensifying the immunotherapeutic response for the efficient killing of cancer cells. Additionally, the successful inhibition of liver cancer metastasis to the lungs and robust increase in T memory cells further boosted the anti-tumor therapeutic efficacy of SR-ATO-ASIV@NS. In summary, SR-ATO-ASIV@NS represents a novel and scientifically sophisticated strategy in targeted biomimetic nanotherapeutics. This approach not only enhances site-specific drug delivery but also showcases promising potential for advancing the field of combined chemoimmunotherapy for liver cancer.

BCL2A1 neoepitope-elicited cytotoxic T lymphocytes are a promising individualized immunotherapy of pancreatic cancer.

Conventional treatments have shown a limited efficacy for pancreatic cancer, and immunotherapy is an emerging option for treatment of this highly fatal malignancy. Neoantigen is critical to improving the efficacy of tumor-specific immunotherapy. The cancer and peripheral blood specimens from an HLA-A0201-positive pancreatic cancer patient were subjected to next-generation sequencing, and bioinformatics analyses were performed to screen high-affinity and highly stable neoepitopes. The activation of cytotoxic T lymphocytes (CTLs) by dendritic cells (DCs) loaded with mutBCL2A111-20 neoepitope targeting a BCL2A1 mutant epitope was investigated, and the cytotoxicity of mutBCL2A111-20 neoepitope-specific CTLs to pancreatic cancer cells was evaluated. The mutBCL2A111-20 neoepitope was found to present a high immunogenicity and induce CTLs activation and proliferation, and these CTLs were cytotoxic to mutBCL2A111-20 neoepitope-loaded T2 cells and pancreatic cancer PANC-1-Neo and A2-BxPC-3-Neo cells that overexpressed mutBCL2A111-20 neoepitopes, appearing to be a targeting neoepitope specificity. In addition, high BCL2A1 expression correlated with a low 5-yr progression-free interval among pancreatic cancer patients. Our findings provide experimental supports to individualized T cell therapy targeting mutBCL2A111-20 neoepitopes, and provide an option of immunotherapy for pancreatic cancer.

Systemic versus localized Bacillus Calmette Guérin immunotherapy of bladder cancer promotes an anti-tumoral microenvironment: Novel role of trained immunity.

Treatment for higher-risk non-muscle invasive bladder cancer (NMIBC) involves intravesical immunotherapy with Bacillus Calmette Guérin (BCG); however, disease recurrence and progression occur frequently. Systemic immunity is critical for successful cancer immunotherapy; thus, recurrence of NMIBC may be due to suboptimal systemic activation of anti-tumor immunity after local immunotherapy. We previously reported that systemically acquired trained immunity (a form of innate immune memory) in circulating monocytes is associated with increased time-to-recurrence in patients with NMIBC treated with BCG. Herein, we used a mouse model of NMIBC to compare the effects of intravesical versus intravenous (systemic) BCG immunotherapy on the local and peripheral immune microenvironments. We also assessed whether BCG-induced trained immunity modulates anti-tumor immune responses. Compared with intravesical BCG, which led to a tumor-promoting immune microenvironment, intravenous BCG resulted in an anti-tumoral bladder microenvironment characterized by increased proportions of cytotoxic T lymphocytes (CTLs), and decreased proportions of myeloid-derived suppressor cells. Polarization toward anti-tumoral immunity occurred in draining lymph nodes, spleen, and bone marrow following intravenous versus intravesical BCG treatment. Pre-treatment with intravesical BCG was associated with increased rate of tumor growth compared with intravenous BCG pre-treatment. Trained immunity contributed to remodeling of the tumor immune microenvironment, as co-instillation of BCG-trained macrophages with ovalbumin-expressing bladder tumor cells increased the proportion of tumor-specific CTLs. Furthermore, BCG-trained dendritic cells exhibited enhanced antigen uptake and presentation and promoted CTL proliferation. Our data support the concept that systemic immune activation promotes anti-tumor responses, and that BCG-induced trained immunity is important in driving anti-tumor adaptive immunity.

MCT1 gene silencing enhances the immune effect of dendritic cells on cervical cancer cells.

Dendritic cells (DCs) are a key class of immune cells that migrate to the draining lymph nodes and present processed antigenic peptides to lymphocytes after being activated by external stimuli, thereby establishing adaptive immunity. Moreover, DCs play an important role in tumor immunity. The aim of the study was to investigate whether MCT1 gene silencing in DCs affects their ability to mount an immune response against cervical cancer cells. We silenced the expression of MCT1 in DCs from mouse bone marrow (BM) by infection with adenovirus. The surface antigen profile of DCs was analyzed by flow cytometry and cytokine secretion was evaluated using enzyme-linked immunosorbent assay (ELISA) following sodium lactate (sLA) exposure and lipopolysaccharide (LPS) stimulation. Then, various groups of DC-induced cytotoxic T lymphocytes (CTLs) were prepared and their cytotoxicity against U14 was tested. Without sLA exposure, silencing MCT1 did not affect the expression of CD1a, CD80, CD83, CD86, and major histocompatibility complex class II (MHCII) in DCs after LPS challenge. Similar results were found for interleukin (IL)-6, IL-12 p70 and tumor necrosis factor alpha (TNF-α). After sLA exposure, silencing MCT1 significantly decreased the expression of CD1a, CD80, CD83, CD86, and MHCII in DCs after the LPS challenge, as well as the secretion of IL-6, IL-12 p70 and TNF-α. In addition, sLA exposure significantly reduced the toxicity and inhibited the proliferation of DC-induced CTLs compared to U14 cells in vitro and in vivo. However, silencing MCT1 significantly attenuated the changes caused by sLA exposure. At the same time, in the absence of sLA, silencing MCT1 did not affect the toxicity nor inhibit the proliferation of DC-induced CTLs on U14 cells. Lactate exposure reduces the immune effect of DCs on cervical cancer cells, but MCT1 gene silencing attenuates these alterations.

Angioimmunoblastic T-Cell Lymphoma with Concurrent EBV Viremia: A Challenging Case

Abstract Introduction/Objective Angioimmunoblastic T-cell lymphoma (AITL) represents only 1-2% of all non-Hodgkin lymphomas but is one of the most common non-cutaneous T-cell lymphomas. Although typically associated with latent Epstein Barr Virus (EBV) infection, recent studies have demonstrated the presence and prognostic impact of EBV viremia at the time of diagnosis. Here, we present a case of AITL in which the diagnosis was complicated by EBV viremia. Methods/Case Report A 41-year-old male presented to our hospital with generalized abdominal pain, diffuse lymphadenopathy, hepatomegaly, ascites, and diffuse body wall edema. A recent retroperitoneal lymph node biopsy reportedly demonstrated features suggesting an infectious process, and EBV PCR revealed a viral load of 141,050 copies/mL. A left axillary lymph node was excised, which demonstrated vascular proliferation and diffuse architectural effacement by a polymorphous infiltrate including variably sized lymphocytes with moderate to abundant clear cytoplasm, and occasional admixed neutrophils, plasma cells, and eosinophils. Immunohistochemical staining demonstrated an atypical CD4-positive, CD7-negative T-cell population in a vaguely nodular distribution, expressing Bcl-6, PD-1, ICOS, and CXCL13 without definite CD10 expression. CD21 immunostaining demonstrated markedly expanded follicular dendritic cell meshworks in a distribution similar to the atypical T-cell population. No B-cell or cytotoxic T-cell proliferation was seen, and in situ hybridization for EBV-encoded RNA (EBER ISH) demonstrated only scattered EBV- positive cells. Taken together, these findings supported a diagnosis of AITL over an atypical reaction to EBV infection. Next-generation sequencing demonstrated mutations in TET2, IDH2, and RHOA, further confirming the diagnosis. Results (if a Case Study enter NA) NA Conclusion AITL manifests with a diverse range of clinical symptoms and pathological features and may mimic infection. Additionally, acute EBV infection is well-known to mimic various lymphomas and has rarely been reported to mimic AITL. We present this case to raise awareness of the concurrent presentation of AITL with EBV viremia and to highlight features that may be helpful in distinguishing between the two.

The Impact of KIR-HLA Interplay in T-LGL Leukemia

T-Cell large granulocyte lymphocyte leukemia (T-LGLL), characterized by clonal expansions of cytotoxic T cells (CTLs), arises from polyclonal lymphoproliferative responses. Various triggers have been stipulated, ranging from autoimmune, viral or tumor antigens. However, one could also posit that an inherent propensity to overshooting CTL responses contributing to the initial clonal expansions or affecting normal termination of immune response might be at play. For instance, specific HLA risk alleles may be overrepresented or even diagnostic for certain autoimmune conditions. In contrast to the risk allele theory, which enriches haplotypes within the patient population, the concept of HLA evolutionary diversity (HED) posits that the structural divergence between alleles widen the recognition spectrum. HLA alleles also serve as ligands for killer immunoglobulin-like receptors (KIRs). Indeed, the KIR gene family, consisting of 15 genes and 2 pseudogenes, is responsible for regulating the activity of NK and a subset of T cells and thus may play a role in T-LGLL. The main KIR genes are classified as either activating or inhibiting, based on their ability to up or downregulate NK and T cells. As the KIR genes and their HLA ligands genetically assort independently of each other, KIR-HLA “mismatches” are possible. We analyzed HLA alleles in 91 T-LGLL patients vs 130 controls and investigated whether specific presentations of T-LGLL, namely neutropenia and anemia enrich for certain HLA alleles. We found that HLA-A*02 was more frequent in cases with neutropenia (59 vs 47%, p=0.045) and HLA-A*68 in patients with anemia (17 vs 8%, p=0.02) as compared to controls. Interestingly, HLA-A*02/HLA-C*05 was observed typically in STAT3 MT vs WT cases (22 vs 11%). Using the HLA calls, we calculated the HED for HLA class 1/2, but no increased HED could be asserted (consistent with the presence of risk alleles as described above). We then explored whether specific KIR-HLA interactions enhanced an individual's risk for clonal CTL expansion and subsequent T-LGLL occurrence. As KIR gene frequencies can vary based on ethnicity, controls were chosen to match T-LGLL cohort (European ancestry). We applied T1K as a computational method for KIR genotyping and validated the calls by the 4 framework KIR genes (always present): 3DL2, 3DL3, 3DP1, and 2DL4. Along with the framework KIRs, there were no differences in the frequency of KIR genotype between T-LGLL and ethnicity matched controls. However, we found that the frequency of individuals with the 3DL2 gene and either HLA A*03 or HLA A*11 was significantly higher in the T-LGLL compared to controls (26 vs 8%, p = .006). Moreover, we found a higher frequency of 2DL3 combined with HLA C2/C2, (31 vs 14%, p=0.05) in T-LGLL patients with neutropenia. As this KIR-ligand (KIRL) configuration is a mismatch, the normally inhibiting receptor will have no effect on cell activity. Stratified by the presence of anemia, the LGLL cohort had instead a significantly higher proportion of 2DS2 co-expressed with the HLA C1 allele (75.68 vs 35.39%, p=.001), indicating activating genotype. We also found that the number of cases with the co-occurrence of the 3DL2 receptor and absent HLA A*03/A*11 ligands paired with 2DL3 and the HLA C1/C1 allotype was higher in STAT3 MT compared to WT (39.1 vs 16.7% p=0.06). Finally, we attempted to estimate and compare the net KIR activity of T-LGLL patients and controls by creating a formula in which, for each individual, we subtracted the sum of the number of KIR/KIRL inhibitory matches from that of activating KIR/KIRL matches. Mismatches were also included either as activating or inhibiting depending on the KIR/KIRL configuration. Using this formula, we found that the net KIR average value for the control cohort was 0.85 compared to 0.69 for the T-LGLL cohort, indicating that the control cohort had slightly more activating KIR-ligand configurations. Even when mismatches were treated as neutral, the preexcitation balance was not changed in T-LGLL. These findings suggest that other factors may contribute to the baseline preexcitation levels of clonal CTLs in this disease. In conclusion, our study of HLA and KIR-HLA interactions shows modest impact of KIR and KIR-ligand genotype on the propensity for overshooting clonal CTL proliferation and points towards other possible mechanisms such as hypersecretion of high affinity IL6R or other stimulatory factors.

Incidence and treatment of checkpoint inhibitor induced immune related adverse events in the emergency department.

438 Background: Immune checkpoint inhibitors (ICPis) are currently indicated for the treatment of various types of cancers. Through inhibition of the cancer cell’s checkpoint mediated T-cell evasion, ICPis allow for sustained T-cell activation and proliferation, resulting in increased cancer cell death. However, due to increased activation and proliferation of cytotoxic T-cells, ICPis have been associated with a wide spectrum of adverse effects, known as immune related adverse effects (irAEs). Although recently updated, the 2018 NCCN and ASCO guidelines state that treatment is based on the location and severity of irAEs. In general, grade 3 toxicities warrant suspension of ICPis and initiation of high-dose corticosteroids. Corticosteroids should then be tapered over the course of at least 4-6 weeks. The diagnosis of an irAE is challenging, toxicities may be misdiagnosed as there is a diverse familiarity with ICPis and their associated irAEs. Subsequently, care may be delayed, and patients may not receive appropriate guideline directed care. Methods: This multi-center chart review included 7 hospitals within a large health system. Our electronic health record was utilized to compile a report of patients who had received ICPIs within 12 months of presentation to an ED within the health system between 9/1/2019 and 9/1/2022. Assessed outcomes included incidence and type of irAE, time between last ICPi dose and presentation to the ED, steroid used for treatment, time to steroid, treatment driver, and the action that deviated from the 2018 ASCO/NCCN guideline directed treatment if applicable. Results: Of the 241 patients receiving an ICPi, 26 (10.8%) experienced an irAE that prompted a visit to an ED within our health system. Guideline directed treatment of irAE(s) was followed 76.9% of the time, with the steroid dose being too low (15.4%) and the steroid taper occurring too quickly (7.7%) being the two reasons for discordant treatment. Treatment started a median of 1.1 after presentation to an ED, with colitis as the most prevalent irAE in 11 patients (42%) presenting. For all patients, there was an average of 20 days between the last ICPi dose and presentation to ED. The main steroid used was methylprednisolone (42%). Conclusions: The 10.8% of patients who experienced an irAE that prompted a visit to an ED within our health system is a lower rate than what has been described in the literature previously, where rates of presentation to an ED due to an irAE ranged from 25-37%. This could be due to previous data coming from before or shortly after the publication of ASCO and NCCN guidelines in 2018, or because our outpatient medical staff has become more aware of irAEs and their appropriate treatment. Limitations include this review was retrospective, no patients had an irAE that was refractory to steroids, and the study period being soon after national guidelines were published.

Mathematical Modeling Reveals Mechanisms of Cancer-Immune Interactions Underlying Hepatocellular Carcinoma Development

Understanding the relationship between hepatocellular carcinoma (HCC) and immunity is crucial for HCC immunotherapy. However, the existing research has solely focused on a novel population of primary tumor-induced non-leukocytes called Ter-cells and their circulating components in distant organs, neglecting the examination of immunity’s impact on cancer. In order to thoroughly examine the dynamics of Ter cells, HCC, and the known regulatory elements in the immunological milieu, we used a mathematical model in the form of a system of differential equations in this work. According to simulation studies, tumor cells cannot be completely eliminated by either the effective killing of HCC by cytotoxic T lymphocytes (CTL) or the inhibition of tumor cell proliferation. Nonetheless, continuous CTL activation and TGF-β-induced differentiation of CTL facilitated a transition from a high steady-state of HCC quantity to an unstable state, followed by a low state of HCC quantity, aligning with the three phases of the cancer immunoediting concept (escape, equilibrium, and elimination). Our survival study revealed that the ratio of CTL proliferation to CTL killing and relative TGF-β-induced differentiation of CTL have a significant impact on cancer-free survival. Sensitivity and bifurcation analysis of these parameters demonstrated that the rate of CTL proliferation, as well as the number of HCCs when the production rate reaches half of one, strongly affects the number of HCCs. Our findings highlight the critical role of immune system activation in cancer therapy and its potential impact on HCC treatment.

The potential role of infusions of T regulatory cells in inducing and maintaining liver allograft tolerance.

1_nse8422sKaltura.

The role of circulating miR-19b miRNA in predicting the outcome of COVID-19

Background. MicroRNAs are short (20–22 nucleotides) non-coding RNAs that can posttranscriptionally regulate gene expression and are considered a regulator of the innate immunity system. Previously, many papers were published on the prediction of the interaction of the single-stranded (+)RNA virus SARS-CoV-2 with human microRNAs, as well as on the profile of circulating microRNAs in patients with COVID-19 of varying severity. However, no works are analyzing the possible contribution of miRNAs circulating in blood plasma to the severity of COVID-19.The aim. To study the features of the blood plasma microRNA profile of patients with different severity of the new coronavirus infection COVID-19 and to evaluate the possibility of microRNA interaction with the SARS-CoV-2 genome.Materials and methods. The results of NGS sequencing of plasma miRNAs of 3 recovered and 8 deceased patients with a highly severe form of COVID-19 were studied. Differentially presented microRNAs were determined using bioinformatics methods, and their binding sites with the SARS-CoV-2 genome were predicted.Results. This study demonstrates that in patients who have recovered from a highly severe form of COVID-19, the level of hsa-miR-19b-3p in the blood plasma is significantly increased. This microRNA makes up about 1.5 % of all circulating microRNAs and can bind to SARS-CoV-2 regions encoding proteins that suppress intracellular immunity mechanisms (NSP3, NSP9). In addition, this miRNA can stimulate the functional activity and proliferation of cytotoxic T-lymphocytes, one of the critical components of acquired cellular immunity against SARS-CoV-2.Conclusion. The results of the study can be used in the development of antiviral drugs based on RNA interference, as well as in the development of predictive test systems to optimize the tactics of treating patients with COVID-19.

Nanodrug removes physical barrier to promote T-cell infiltration for enhanced cancer immunotherapy.

The dense extracellular matrix (ECM) is a key barrier to tumor infiltration of cytotoxic T lymphocytes (CTLs), which greatly compromises T cell-dependent immunotherapy of hepatocellular carcinoma (HCC). Herein, hyaluronidase (HAase), IL-12, and anti-PD-L1 antibody (αPD-L1) were co-delivered using a pH and MMP-2 dual-sensitive polymer/calcium phosphate (CaP) hybrid nanocarrier. The dissolution of CaP triggered by tumor acidity facilitated the release of IL-12 and HAase responsible for ECM digestion, enhancing the tumor infiltration and proliferation of CTLs. Furthermore, the in situ-released αPD-L1 inside tumor, as triggered by an overexpressed MMP-2, prevented the tumor cell from escaping the killing effects of CTLs. Such combination strategy induced a robust antitumor immunity for efficiently suppressing HCC growth in mice. Additionally, tumor acidity-sheddable polyethylene glycol (PEG) coating enhanced the tumor accumulation of nanocarrier and reduced the immune-related adverse events (irAEs) induced by on-target off-tumor αPD-L1. This dual-sensitive nanodrug demonstrates an effective immunotherapy paradigm for other dense ECM-characterized solid tumors.

Key Factors and Parameter Ranges for Immune Control of Equine Infectious Anemia Virus Infection.

Equine Infectious Anemia Virus (EIAV) is an important infection in equids, and its similarity to HIV creates hope for a potential vaccine. We analyze a within-host model of EIAV infection with antibody and cytotoxic T lymphocyte (CTL) responses. In this model, the stability of the biologically relevant endemic equilibrium, characterized by the coexistence of long-term antibody and CTL levels, relies upon a balance between CTL and antibody growth rates, which is needed to ensure persistent CTL levels. We determine the model parameter ranges at which CTL and antibody proliferation rates are simultaneously most influential in leading the system towards coexistence and can be used to derive a mathematical relationship between CTL and antibody production rates to explore the bifurcation curve that leads to coexistence. We employ Latin hypercube sampling and least squares to find the parameter ranges that equally divide the endemic and boundary equilibria. We then examine this relationship numerically via a local sensitivity analysis of the parameters. Our analysis is consistent with previous results showing that an intervention (such as a vaccine) intended to control a persistent viral infection with both immune responses should moderate the antibody response to allow for stimulation of the CTL response. Finally, we show that the CTL production rate can entirely determine the long-term outcome, regardless of the effect of other parameters, and we provide the conditions for this result in terms of the identified ranges for all model parameters.

OR22-6 Ovarian Cancer Cell Glucocorticoid Receptor Activity Is Associated With Cytokine Secretion Promoting Infiltration of Immunosuppressive Cells Into the Tumor Microenvironment

Abstract Immunosuppressive cells abundantly infiltrate tumors during cancer progression. Notably, immunosuppressive myeloid-derived suppressor cells (MDSCs) have recently been identified as a heterogeneous cell population that expand during tumor-associated inflammation and are significantly increased in the tumor, peripheral blood, as well as ascites of ovarian cancer patients. MDSCs contribute to tumor immune tolerance via inhibition of T-cell proliferation and activation. Signals from the tumor microenvironment in the form of soluble cytokines are proposed to lead to MDSC infiltration. It is also known that high tumor cell glucocorticoid receptor (GR) expression is associated with a relatively poor prognosis in ovarian cancer patients. We hypothesized that ovarian cancer cell GR expression and activity may modulate tumor cell cytokine secretion thereby leading to increased MDSC generation and recruitment to the tumor, thereby creating an immunosuppressive environment. Our preliminary data confirm that GR activation in two high-grade ovarian cancer cell lines (HeyA8 and SKOV3) modulates the cytokine secretome. Our results demonstrate GR-mediated secretion of several pro-tumorigenic and immunosuppressive proteins including G-CSF, M-CSF, TGF-b, and MCP-1 in those ovarian cancer models. We also observed downregulation of potent cytotoxic T-cell activating cytokines required for anti-tumor T-cell function including IL-2, IFN-g and MIP1 upon GR activation. Importantly, treatment of cells with a selective GR modulator (SGRM) reverses this immunosuppressive secretome effect. Furthermore, upon culturing healthy peripheral blood mononuclear cells (PBMCs) with tumor conditioned media from GR activated ovarian cancer cells, we show that secreted immunomodulatory factors have the capacity to promote differentiation of human MDSCs from progenitor myeloid cells. The resulting MDSC population was characterized via expression of activation markers including Arginase-1, iNOS, VEGF and TGF-b. Most importantly, the suppressive function of these MDSCs is being evaluated by determining their inhibitory potential on cytotoxic T-cell proliferation and/or activation. Based on the insight provided by these data, we propose to determine whether ovarian tumor cell-intrinsic GR activation and resulting MDSC generation contributes to earlier relapse of GR-positive ovarian cancers, and eventually whether this mechanism may be targeted to improve patient outcomes in this subset of ovarian cancers. Presentation: Monday, June 13, 2022 12:15 p.m. - 12:30 p.m.

EP16.04-005 Investigating the Side Effects of Docetaxel on Rat Lung and Heart

Docetaxel (DTX) is widely used againstmany kinds of solid tumors such as breast, ovarian, prostate and lung. Inhibitionof microtubular depolymerization and attenuation of the effects of bcl-2 andbcl-xL gene expression are the main mechanisms of its antineoplastic effect.Additionally, taxanes are known to cause proliferation of cytotoxic T-cells,leading to a hypersensitivity type of lung damage, or might cause directpulmonary damage through reactive oxygen metabolites.This study has been investigated theside effects of two different doses of DTX on the lung and heart tissue of rats.

Abstract 1335: Ovarian cancer cell glucocorticoid receptor activity is associated with cytokine secretion promoting infiltration of immunosuppressive cells into the tumor microenvironment

Abstract Immunosuppressive cells abundantly infiltrate tumors during cancer progression. Notably, immunosuppressive myeloid-derived suppressor cells (MDSCs) have recently been identified as a heterogeneous cell population that expand during tumor-associated inflammation and are significantly increased in the tumor, peripheral blood, as well as ascites of ovarian cancer patients. MDSCs contribute to tumor immune tolerance via inhibition of T-cell proliferation and activation. Signals from the tumor microenvironment in the form of soluble cytokines are proposed to lead to MDSC infiltration. It is also known that high tumor cell glucocorticoid receptor (GR) expression is associated with a relatively poor prognosis in ovarian cancer patients. We hypothesized that ovarian cancer cell GR expression and activity may modulate tumor cell cytokine secretion thereby leading to increased MDSC generation and recruitment to the tumor, eventually creating an immunosuppressive environment. Our preliminary data confirm that GR activation in two high-grade ovarian cancer cell lines (HEYA8 and SKOV3) modulates the cytokine secretome. Our results demonstrate GR-mediated secretion of several pro-tumorigenic and immunosuppressive proteins including G-CSF, M-CSF, TGF-β, and MCP-1 in those ovarian cancer models. We also observed downregulation of potent cytotoxic T-cell activating cytokines required for anti-tumor T-cell function including IL-2, IFN-γ and MIP1 upon GR activation. Importantly, treatment of cells with a competitive GR antagonist reverses this immunosuppressive secretome effect. Furthermore, upon culturing healthy peripheral blood mononuclear cells (PBMCs) with tumor conditioned media from GR activated ovarian cancer cells, we show that secreted immunomodulatory factors have the capacity to promote differentiation of human MDSCs from PBMCs. The resulting MDSC population was characterized via expression of activation markers including Arginase-1, iNOS, VEGF and TGF-β. Most importantly, the suppressive function of these MDSCs is being evaluated by determining their inhibitory potential on cytotoxic T-cell proliferation and/or activation. Based on the insight provided by these data, we propose to determine whether ovarian tumor cell-intrinsic GR activation and resulting MDSC generation contributes to earlier relapse of GR-positive ovarian cancers, and eventually whether this mechanism may be targeted to improve patient outcomes in this subset of ovarian cancers. Citation Format: Manisha Taya, Janet Gonzalez, Lynda Bennett, Suzanne D. Conzen. Ovarian cancer cell glucocorticoid receptor activity is associated with cytokine secretion promoting infiltration of immunosuppressive cells into the tumor microenvironment [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 1335.

Cytotoxic T Lymphocyte Activation Signals Modulate Cytoskeletal Dynamics and Mechanical Force Generation.

Cytotoxic T lymphocytes (CTLs) play an integral role in the adaptive immune response by killing infected cells. Antigen presenting cells (APCs), such as dendritic cells, present pathogenic peptides to the T cell receptor on the CTL surface and co-stimulatory signals required for complete activation. Activated CTLs secrete lytic granules containing enzymes that trigger target cell death at the CTL-target contact, also known as the immune synapse (IS). The actin and microtubule cytoskeletons are instrumental in the killing of CTL targets. Lytic granules are transported along microtubules to the IS, where granule secretion is facilitated by actin depletion and recovery. Furthermore, actomyosin contractility promotes target cell death by mediating mechanical force exertion at the IS. Recent studies have shown that inflammatory cytokines produced by APCs, such as interleukin-12 (IL-12), act as a third signal for CTL activation and enhance CTL proliferation and effector function. However, the biophysical mechanisms mediating such enhanced effector function remain unclear. We hypothesized that the third signal for CTL activation, IL-12, modulates cytoskeletal dynamics and force exertion at the IS, thus potentiating CTL effector function. Here, we used live cell total internal reflection fluorescence (TIRF) microscopy to study actomyosin and microtubule dynamics at the IS of murine primary CTLs activated in the presence of peptide-MHC and co-stimulation alone (two signals), or additionally with IL-12 (three signals). We found that three signal-activated CTLs have altered actin flows, myosin dynamics and microtubule growth rates as compared to two signal-activated CTLs. We further showed that lytic granules in three-signal activated CTLs are less clustered and have lower velocities than in two-signal activated CTLs. Finally, we used traction force microscopy to show that three signal-activated CTLs exert greater traction forces than two signal-activated CTLs. Our results demonstrate that activation of CTLs in the presence of IL-12 leads to differential modulation of the cytoskeleton, thereby augmenting the mechanical response of CTLs to their targets. This indicates a potential physical mechanism via which the third signal can enhance the CTL response.

Stability analysis of general delayed HTLV-I dynamics model with mitosis and CTL immunity.

This paper formulates and analyzes a general delayed mathematical model which describe the within-host dynamics of Human T-cell lymphotropic virus class I (HTLV-I) under the effect Cytotoxic T Lymphocyte (CTL) immunity. The models consist of four components: uninfected CD$ 4^{+} $T cells, latently infected cells, actively infected cells and CTLs. The mitotic division of actively infected cells are modeled. We consider general nonlinear functions for the generation, proliferation and clearance rates for all types of cells. The incidence rate of infection is also modeled by a general nonlinear function. These general functions are assumed to be satisfy some suitable conditions. To account for series of events in the infection process and activation of latently infected cells, we introduce two intracellular distributed-time delays into the models: (ⅰ) delay in the formation of latently infected cells, (ⅱ) delay in the activation of latently infected cells. We determine a bounded domain for the system's solutions. We calculate two threshold numbers, the basic reproductive number $ R_{0} $ and the CTL immunity stimulation number $ R_{1} $. We determine the conditions for the existence and global stability of the equilibrium points. We study the global stability of all equilibrium points using Lyapunov method. We prove the following: (a) if $ R_{0}\leq 1 $, then the infection-free equilibrium point is globally asymptotically stable (GAS), (b) if $ R_{1}\leq 1 < R_{0} $, then the infected equilibrium point without CTL immunity is GAS, (c) if $ R_{1} > 1 $, then the infected equilibrium point with CTL immunity is GAS. We present numerical simulations for the system by choosing special shapes of the general functions. The effects of proliferation of CTLs and time delay on the HTLV-I progression is investigated. We noted that the CTL immunity does not play the role in clearing the HTLV-I from the body, but it has an important role in controlling and suppressing the viral infection. On the other hand, we observed that, increasing the time delay intervals can have similar influences as drug therapies in removing viruses from the body. This gives some impression to develop two types of treatments, the first type aims to extend the intracellular delay periods, while the second type aims to activate and stimulate the CTL immune response.