Levels Of Myeloid-derived Suppressor Cells Research Articles

Interleukin-1 receptor 1 deficiency worsens hepatocellular carcinoma, while gemcitabine treatment alleviates the hepatocellular carcinoma-induced increase in intra-hepatic immune cells.

Primary liver cancer, particularly hepatocellular carcinoma (HCC), represents a substantial global health challenge. Although immune checkpoint inhibitors are effective in HCC treatment, several patients still experience disease progression. Interleukin-1 (IL-1) regulates immunity and inflammation. We investigate the role of IL-1 in HCC development and progression and determine the potential therapeutic impact of gemcitabine in treating HCC. Hydrodynamics-based transfection, employing the sleeping beauty transposase system, delivered surrogate tumor antigens, NRAS (NRAS proto-oncogene, GTPase), ShP53, and SB100 to C57BL/6 mice. A basic HCC mouse model was established. Pathogen-free animals were tested for serum and hepatotoxicity. The HCC prognosis was monitored using alanine aminotransferase and aspartate aminotransferase levels. Liver histology immunohistochemistry and mouse splenocyte/intra-hepatic immune cell flow cytometry were conducted. IL-1β levels in human and mouse serum were assessed. Interleukin-1β levels were elevated in patients with HCC compared with those in non-HCC controls. Hepatic IL-1β levels were higher in HCC mouse models than those in non-HCC mice, suggesting localized hepatic inflammation. IL-1 receptor type 1 (IL-1R1) knockout (IL-1R1-/-) mice exhibited less severe HCC progression than that in wild-type mice, despite the high intra-hepatic IL-1β concentration. IL-1R1-/- mice exhibited increased hepatic levels of myeloid-derived suppressor cells and regulatory T cells, which may exacerbate HCC. Gemcitabine significantly reduced the HCC tumor burden, improved liver conditions, and increased survival rates in HCC mouse models. Gemcitabine reduced the hepatic levels of myeloid-derived suppressor cells and regulatory T cells, potentially alleviating immune suppression in the liver. Targeting IL-1 or combining gemcitabine with immunotherapy is a promising approach for treating advanced-stage HCC.

Comprehensive mapping of immune perturbations associated with secondary hemophagocytic lymphohistiocytosis.

Secondary hemophagocytic lymphohistiocytosis (sHLH) is a hyperinflammatory syndrome characterized by immune disorders. It is imperative to elucidate the immunophenotypic panorama and the interactions among these cells in patients. Human peripheral blood mononuclear cells were collected from healthy donors and sHLH patients and tested using multicolor flow cytometry. We used FlowSOM to explore and visualize the immunophenotypic characteristics of sHLH. By demonstrating the phenotypes of immune cells, we discovered that sHLH patients had significantly higher levels of CD56+ monocytes, higher levels of myeloid-derived suppressor cells, low-density neutrophil-to-T cell ratio, and higher heterogeneous T cell activation than healthy donors. However, natural killer cell cytotoxicity and function were impaired. We then assessed the correlations among 30 immune cell types and evaluated metabolic analysis. Our findings demonstrated polymorphonuclear myeloid-derived suppressor cells, CD56+ monocytes, and neutrophil-to-T cell ratio were elevated abnormally in sHLH patients, which may indicate an association with immune overactivation and inflammatory response. We are expected to confirm that they are involved in the occurrence of the disease through further in-depth research.

Inhibition of non-small cell lung cancer metastasis by knocking down APE1 through regulating myeloid-derived suppressor cells-induced immune disorders.

Non-small cell lung cancer (NSCLC) represents a highly immunogenic malignancy. Immunologic tolerance facilitated by myeloid-derived suppressor cells (MDSCs) is implicated in primary or secondary resistance mechanisms in NSCLC. The potential role of APE1 in regulating NSCLC metastasis by targeting MDSCs remains uncertain. This study utilized a plasmid, Plxpsp-mGM-CSF, to induce elevated granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in A549 cells. Tumor transplantation experiments involved A549, A549+GM-CSF, and A549+GM-CSF-siAPE1 cell lines. Evaluation encompassed MDSCs, Treg cells, IgG, CD3, and CD8 levels. Notably, lung cancer tissues and cells displayed markedly reduced APE1 expression. siAPE1 transfection significantly curtailed tumor growth compared to the A549+GM-CSF group. APE1 knockdown orchestrated immune system modulation in lung tumor mice, characterized by diminished MDSCs but augmented Treg cells, IgG, CD3, and CD8. Additionally, APE1 knockdown led to reduced levels of pro-MDSC cytokines (HGF, CCL5, IL-6, CCL12) and a concurrent upregulation of the anti-MDSC cytokine IL-1ra. Furthermore, APE1 knockdown impeded cell viability in both A549 and H1650 cells. Transplantation of A549-GM-CSF amplified MDSC levels, fostering accelerated tumor growth, while mitigating MDSC levels through APE1 knockdown hindered tumor progression and alleviated inflammatory infiltration in lung cancer tissues. Strategies targeting the APE1/MDSC axis offer a promising approach for lung cancer prevention and treatment, presenting novel insights for NSCLC management.

Increased circulating polymorphonuclear myeloid-derived suppressor cells are associated with prognosis of metastatic castration-resistant prostate cancer.

Myeloid-derived suppressor cell (MDSC) exhibits immunosuppressive functions and affects cancer progression, but its relationship with prostate cancer remains unclear. We elucidated the association of polymorphonuclear MDSC (PMN-MDSC) and monocytic MDSC (M-MDSC) levels of the total peripheral blood mononuclear cells (PBMCs) with prostate cancer progression and evaluated their roles as prognostic indicators. We enrolled 115 patients with non-metastatic hormone-sensitive prostate cancer (nmHSPC, n = 62), metastatic hormone-sensitive prostate cancer (mHSPC, n = 23), and metastatic castration-resistant prostate cancer (mCRPC, n = 30). Subsequently, the proportions of MDSCs in each disease progression were compared. Log-rank tests and multivariate Cox regression analyses were performed to ascertain the associations of overall survival. The patients with mCRPC had significantly higher PMN-MDSC percentage than those with nmHSPC and mHSPC (P = 7.73 × 10-5 and 0.0014). Significantly elevated M-MDSC levels were observed in mCRPC patients aged <70 years (P = 0.016) and with a body mass index (BMI) <25 kg/m2 (P = 0.043). The high PMN-MDSC group had notably shorter median survival duration (159 days) than the low PMN-MDSC group (768 days, log-rank P = 0.018). In the multivariate analysis including age, BMI, and MDSC subset, PMN-MDSC was significantly associated with prognosis (hazard ratios, 3.48; 95% confidence interval: 1.05-11.56, P = 0.042). PMN-MDSC levels are significantly associated with mCRPC prognosis. Additionally, we highlight the remarkable associations of age and BMI with M-MDSC levels in mCRPC, offering novel insights into MDSC dynamics in prostate cancer progression.

Phase 1 study of anti–immunoglobulin-like transcript 3 (ILT3) monoclonal antibody (mAb) MK-0482 + pembrolizumab (pembro) in patients with recurrent inoperable glioblastoma (GBM).

2046 Background: For patients with GBM, treatment options are limited once the disease has recurred and become inoperable after standard first-line therapy. ILT3 is an inhibitory receptor expressed on monocytic myeloid cells, including tolerogenic dendritic cells and myeloid-derived suppressor cells (MDSCs). High expression of ILT3 on these immune cells has been associated with immune tolerance and suppression of T-cell function. Data have shown that GBMs have high ILT3 expression and high levels of MDSCs within the tumor microenvironment (TME). MK-0482 is a novel humanized IgG4 mAb targeting ILT3. Inhibition of ILT3 with MK-0482 may help relieve immunosuppression and improve T-cell function within the TME. In the expansion cohort of the first-in-human phase 1 study (MK-0482-001; NCT03918278), MK-0482 was evaluated in combination with pembro in a cohort of patients with recurrent inoperable GBM. The safety and efficacy data from this cohort are presented herein. Methods: Patients aged ≥18 y with their first recurrent inoperable GBM and a Karnofsky performance status (KPS) ≥80 were enrolled. Patients received MK-0482 750 mg Q3W + pembro 200 mg Q3W IV for up to a maximum of 35 cycles. The primary objective was to determine safety and tolerability of MK-0482 + pembro. Secondary objectives were to evaluate ORR, DCR (CR + PR + SD), and DOR by investigator assessment per Response Assessment in Neuro-Oncology (RANO). Exploratory objectives included evaluation of PFS per RANO and OS. Results: Overall, 25 patients were enrolled and received study treatment. At data cutoff (October 3, 2023), median follow-up duration was 9.3 mo (range, 5.6-14.5); treatment was ongoing in 1 patient. Median age was 56 y (range, 33-76). Most patients were male (72%), had a KPS of 80 (68%), and had IDH1 wild-type tumors (88%). All patients had previously received systemic therapy: 24 of 25 (96%) received prior temozolomide and 3 of 25 (12%) received prior glasdegib. Overall, 22 patients (88%) had an adverse event (AE); 10 patients (40%) had treatment-related AEs, most commonly (≥10%) arthralgia (12%), fatigue (12%), and increased ALT (12%). Grade 3 treatment-related AEs occurred in 2 patients (8%; increased ALT [n = 1] and fatigue [n = 1]). No grade 4 or 5 treatment-related AEs occurred. Four patients (16%) experienced immune-mediated AEs (hypothyroidism, n = 2; hepatitis, n = 1; pancreatitis, n = 1); all were grade 1 or 2. Confirmed ORR was 12% (3/25; 95% CI, 2.5-31.2), DCR was 32% (8/25; 14.9-53.5), and median DOR was 11.1 mo (range, 9.9-16.6+). Median PFS was 1.4 mo (95% CI, 1.3-2.9) and median OS was 9.3 mo (6.3-13.7); 6-/12-mo PFS and OS rates were 24%/16% and 72%/36%, respectively. Biomarker data will be included in the presentation. Conclusions: MK-0482 + pembro had a manageable AE profile with modest antitumor activity in patients with recurrent inoperable GBM. Clinical trial information: NCT03918278 .

Myeloid-derived suppressor cells in peripheral blood as predictive biomarkers in patients with solid tumors undergoing immune checkpoint therapy: systematic review and meta-analysis

BackgroundImmunotherapeutic approaches, including immune checkpoint inhibitor (ICI) therapy, are increasingly recognized for their potential. Despite notable successes, patient responses to these treatments vary significantly. The absence of reliable predictive and prognostic biomarkers hampers the ability to foresee outcomes. This meta-analysis aims to evaluate the predictive significance of circulating myeloid-derived suppressor cells (MDSC) in patients with solid tumors undergoing ICI therapy, focusing on progression-free survival (PFS) and overall survival (OS).MethodsA comprehensive literature search was performed across PubMed and EMBASE from January 2007 to November 2023, utilizing keywords related to MDSC and ICI. We extracted hazard ratios (HRs) and 95% confidence intervals (CIs) directly from the publications or calculated them based on the reported data. A hazard ratio greater than 1 indicated a beneficial effect of low MDSC levels. We assessed heterogeneity and effect size through subgroup analyses.ResultsOur search yielded 4,023 articles, of which 17 studies involving 1,035 patients were included. The analysis revealed that patients with lower levels of circulating MDSC experienced significantly improved OS (HR=2.13 [95% CI 1.51–2.99]) and PFS (HR=1.87 [95% CI 1.29–2.72]) in response to ICI therapy. Notably, heterogeneity across these outcomes was primarily attributed to differences in polymorphonuclear MDSC (PMN-MDSC) subpopulations and varying cutoff methodologies used in the studies. The monocytic MDSC (M-MDSC) subpopulation emerged as a consistent and significant prognostic marker across various subgroup analyses, including ethnicity, tumor type, ICI target, sample size, and cutoff methodology.ConclusionsOur findings suggest that standardized assessment of MDSC, particularly M-MDSC, should be integral to ICI therapy strategies. These cells hold the promise of identifying patients at risk of poor response to ICI therapy, enabling tailored treatment approaches. Further research focusing on the standardization of markers and validation of cutoff methods is crucial for integrating MDSC into clinical practice.Systematic Review Registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023420095, identifier CRD42023420095.

Hepatic recruitment of myeloid-derived suppressor cells upon liver injury promotes both liver regeneration and fibrosis

BackgroundThe liver regeneration is a highly complicated process depending on the close cooperations between the hepatocytes and non-parenchymal cells involving various inflammatory cells. Here, we explored the role of myeloid-derived suppressor cells (MDSCs) in the processes of liver regeneration and liver fibrosis after liver injury.MethodsWe established four liver injury models of mice including CCl4-induced liver injury model, bile duct ligation (BDL) model, concanavalin A (Con A)-induced hepatitis model, and lipopolysaccharide (LPS)-induced hepatitis model. The intrahepatic levels of MDSCs (CD11b+Gr-1+) after the liver injury were detected by flow cytometry. The effects of MDSCs on liver tissues were analyzed in the transwell co-culture system, in which the MDSCs cytokines including IL-10, VEGF, and TGF-β were measured by ELISA assay and followed by being blocked with specific antibodies.ResultsThe intrahepatic infiltrations of MDSCs with surface marker of CD11b+Gr-1+ remarkably increased after the establishment of four liver injury models. The blood served as the primary reservoir for hepatic recruitment of MDSCs during the liver injury, while the bone marrow appeared play a compensated role in increasing the number of MDSCs at the late stage of the inflammation. The recruited MDSCs in injured liver were mainly the M-MDSCs (CD11b+Ly6G−Ly6Chigh) featured by high expression levels of cytokines including IL-10, VEGF, and TGF-β. Co-culture of the liver tissues with MDSCs significantly promoted the proliferation of both hepatocytes and hepatic stellate cells (HSCs).ConclusionsThe dramatically and quickly infiltrated CD11b+Gr-1+ MDSCs in injured liver not only exerted pro-proliferative effects on hepatocytes, but also accounted for the activation of profibrotic HSCs.

Listeria-vectored cervical cancer vaccine candidate strains reduce MDSCs via the JAK-STAT signaling pathway.

Immunosuppressive status is prevalent in cancer patients and increases the complexity of tumor immunotherapy. It has been found that Listeria-vectored tumor vaccines had the potential ability of two-side regulatory effect on the immune response during immunotherapy. The results show that the combined immunotherapy with the LM∆E6E7 and LI∆E6E7, the two cervical cancer vaccine candidate strains constructed by our lab, improves the antitumor immune response and inhibits the suppressive immune response in tumor-bearing mice in vivo, confirming the two-sided regulatory ability of the immune response caused by Listeria-vectored tumor vaccines. The immunotherapy reduces the expression level of myeloid-derived suppressor cells (MDSCs)-inducing factors and then inhibits the phosphorylation level of STAT3 protein, the regulatory factor of MDSCs differentiation, to reduce the MDSCs formation ability. Moreover, vaccines reduce the expression of functional molecules associated with MDSCs may by inhibiting the phosphorylation level of the JAK1-STAT1 and JAK2-STAT3 pathways in tumor tissues to attenuate the immunosuppressive function of MDSCs. Immunotherapy with Listeria-vectored cervical cancer vaccines significantly reduces the level and function of MDSCs in vivo, which is the key point to the destruction of immunosuppression. The study for the first to elucidate the mechanism of breaking the immunosuppression.

SUPPRESSOR CELLS (MDSC) REGULATE THE T-CELL RESPONSE IN OLD MICE IMMUNIZED WITH THE WHOLE-VIRION SARS-CoV-2 VACCINE

Myeloid-derived suppressor cells (MDSCs) are an immunosuppressive population involved in pathological processes associated with chronic inflammation. In recent years, the role of these cells in the regulation of a number of non-pathological processes, in particular, in the development of vaccine-induced immune response, has been actively discussed. This work was aimed at investigating the role of MDSC in the development of an immune response in old mice immunized with an inactivated whole virion SARS-CoV-2. Immunization of old animals induced an increase in the relative content of B cells and the production of specific antibodies to S1 and N proteins of SARS-CoV-2 in titers comparable to those of young animals. At the same time, elevated MDSC levels in aged animals negatively correlated with the level of CD8+ T cells. Splenic MDSCs in old animals were characterized by increased production of reactive oxygen species compared to young animals. In vitro experiments showed that MDSC depletion increased antigen-specific production of IFNγ by CD4+ T cells. The data obtained suggest a negative role for MDSC in regulating the T-cell vaccine-induced response to inactivated SARS-CoV-2 and encourage further studies in this direction, which may be a key to developing approaches to increase the efficacy of vaccines against SARS-CoV-2 in at-risk groups.

Evaluating Leukocyte Telomere Length and Myeloid-Derived Suppressor Cells as Biomarkers for Prostate Cancer.

Leukocyte telomere length (LTL) and myeloid-derived suppressor cells (MDSC) are associated with aging and the development and progression of cancer. However, the exact nature of this relationship remains unclear. Our study aimed to investigate the potential of LTL and MDSC as diagnostic biomarkers for prostate cancer while also seeking to deepen our understanding of the relationship of these potential biomarkers to each other. Our study involved patients undergoing a prostate biopsy. We analyzed the relative LTL in genomic DNA obtained from peripheral blood leukocytes as well as the percentage of MDSC and their subtypes in peripheral blood mononuclear cells (PBMC). Our evaluation focused on examining the relationship between LTL and MDSC and pathological diagnoses as well as investigating the correlation between LTL and MDSC levels. In our study of 102 participants, 56 were pathologically diagnosed with localized prostate cancer (cancer group), while 46 tested negative (control group). The cancer group exhibited significantly shorter LTL in comparison to the control group (p = 0.024). Additionally, the cancer group showed a tendency towards a higher percentage of monocytic MDSC (M-MDSC), although this difference did not reach statistical significance (p = 0.056). Our multivariate logistic regression analysis revealed that patients with shorter LTL and higher percentages of M-MDSC had a 2.98-fold (95% CI = 1.001-8.869, p = 0.049) and 3.03-fold (95% CI = 1.152-7.977, p = 0.025) increased risk of prostate cancer diagnosis, respectively. There was also a significant negative correlation between LTL and M-MDSC. (r = -0.347, p < 0.001). Our research has established a correlation between LTL and MDSC in patients undergoing biopsy for prostate cancer. Notably, we observed that individuals with localized prostate cancer tend to have shorter LTL and a higher percentage of M-MDSC prior to their diagnosis. These findings suggest that LTL and M-MDSC could potentially serve as adjunctive biomarkers for the early diagnosis of prostate cancer.

Abstract 1831: Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression

Abstract Frequent consumption of edible mushrooms, such as white button mushrooms (WBM), has been associated with a lower risk of prostate cancer [1]. Our laboratory at City of Hope has over 20 years of collective experience in defining the anticancer mechanisms of WBM [2, 3]. Previous studies have indicated that WBM consumption has anti-androgenic activities in prostate cancers in both preclinical models [4] and clinical trials [5]. In our first-in-human phase 1 trial on prostate cancer patients, we ensured the safety of consuming WBM in humans. In addition to observing a therapeutic-responsive decline in prostate-specific antigen (PSA), the levels of myeloid-derived suppressor cells (MDSCs) reduced in responders to WBM treatments [5]. These observations led us to hypothesize that WBM may mitigate the progression of prostate cancer in part by modulating the immune response. In the current study, we conducted translational research in syngeneic murine models and in prostate cancer patients from an ongoing phase 2 trial, aiming to define the immunomodulatory activity and mechanisms of WBM. We confirmed that WBM consumption in mouse models altered the number and function of immunosuppressive cells (MDSCs) and anti-tumor immune cells (T &amp; NK cells), ultimately enhancing the intratumor and systemic immune responses. At a bulk-transcriptional level, we observed the elevated expression of programmed cell death protein 1 (PD-1) in xenograft tumors. In our single immune cell profiling of patients’ blood specimens following 3 months of WBM consumption in freeze-dried tablets form, we investigated the transcriptional landscape of circulating immune cells in response to WBM interventions. The level of circulating neutrophil-associated PMN-MDSCs decreased, and the remaining cells showed transcriptional profiles associated with "neutrophil chemotaxis", "leukocyte aggregation", and "regulation of inflammatory response", as functions associated with enhanced anti-tumor activity. Lastly, we also showed in a mouse model that WBM consumption synergistically enhances the anticancer activity of anti-PD1 drugs, indicating that WBM may be used as adjuvant therapy with immune checkpoint inhibitors. In summary, our results from prostate cancer patients and murine models show the immunomodulatory effects of WBM consumption and provide a scientific foundation for the application of WBM in alleviating prostate cancer progression. References 1, Zhang S., et al. Int. J. Cancer. 2019; 146:2712-2720. 2, Chen S., et al. Cancer Res. 2006; 66:12026-12034. 3, Adams L.S., et al. Nutr. Cancer. 2008; 60:744-756. 4, Wang X., et al. J. Nutr. Biochem. 2021; 89:108580.5, Twardowski P., et al. Cancer. 2015; 121:2942-2950. Citation Format: Xiaoqiang Wang, Shoubao Ma, Przemyslaw Twardowski, Clayton Lau, Yin Chan, Kelly Wong, Jinhui Wang, Xiwei Wu, Paul Frankel, Timothy G. Wilson, Timothy W. Synold, Cary Presant, Jianhua Yu, Shiuan Chen. Reduction of PMN-MDSC level/activity following the consumption of white button mushroom in prostate cancer murine models and patients: A translational study to mitigate cancer progression [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 1831.

Knock down of APE1 suppressed gastric cancer metastasis via improving immune disorders caused by myeloid-derived suppressor cells

ABSTRACT Gastric cancer is a highly immunogenic malignancy. Immune tolerance facilitated by myeloid-derived suppressor cells (MDSCs) has been implicated in gastric cancer resistance mechanisms. The potential role of APE1 in regulating gastric cancer metastasis by targeting MDSCs remains uncertain. In this study, the plasmid Plxpsp-mGM-CSF was used to induce high expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in GES-1 cells. For tumor transplantation experiments, AGS, AGS+GM-CSF and AGS+GM-CSF-siAPE1 cell lines were established by transfection, followed by subcutaneous implantation of tumor cells. MDSCs, Treg cells, IgG, CD3 and CD8 levels were assessed. Transfection with siAPE1 significantly inhibited tumor growth compared to the AGS+GM-CSF group. APE1 gene knockdown modulated the immune system in gastric cancer mice, characterized by a decrease in MDSCs and an increase in Treg cells, IgG, CD3 and CD8. In addition, APE1 gene knockdown resulted in decreased levels of pro-MDSC cytokines (HGF, CCL5, IL-6, CCL12). Furthermore, APE1 gene knockdown inhibited proliferation, migration and invasion of AGS and MKN45 cells. AGS-GM-CSF cell transplantation increased MDSC levels and accelerated tumor growth, whereas APE1 knockdown reduced MDSC levels, inhibited tumor growth and attenuated inflammatory infiltration in gastric cancer tissues. Strategies targeting the APE1/MDSC axis offer a promising approach to the prevention and treatment of gastric cancer, providing new insights into its management.

Myeloid derived suppressor cells in peripheral blood can be a prognostic factor in canine transitional cell carcinoma

Myeloid-derived suppressor cells (MDSCs) are immature cells with immunosuppressive properties found in the tumor microenvironment. MDSCs are divided into two major subsets: polymorphonuclear MDSCs (PMN-MDSCs) and monocytic MDSCs (M-MDSCs). Both MDSC subsets contribute to the creation of an immunosuppressive environment for tumor progression. In humans, patients with high levels of MDSCs show worse outcomes for several types of cancers. However, the association between MDSCs and clinical features has rarely been investigated in canine studies. In the present study, we measured the proportion of PMN-MDSCs and M-MDSCs in the peripheral blood and tumor tissue of dogs with hepatocellular carcinoma (HCC), prostate cancer (PC), transitional cell carcinoma (TCC), lymphoma, and pulmonary adenocarcinoma. Additionally, we examined immunosuppressive ability of PMN-MDSCs and M-MDSCs in peripheral blood mononuclear cells of TCC case on CD4+, CD8+ and interferon-γ+ cells and investigated the relationships of MDSCs with clinical features and outcomes. PMN-MDSCs increased in HCC, PC, TCC, and lymphoma. In contrast, M-MDSCs increased in the TCC. Both PMN-MDSCs and M-MDSCs exhibited immunosuppressive effects on CD8+, CD4+ and interferon-γ+ cells. In dogs with TCC, lymph node metastasis was associated with high level of PMN-MDSCs but not with M-MDSCs. High levels of both PMN-MDSCs and M-MDSCs were related to advanced tumor stage. Kaplan-Meier analysis revealed that high levels of both PMN-MDSCs and M-MDSCs were significantly associated with shorter overall survival. In addition, the Cox proportional hazard regression model showed that M-MDSCs and the tumor stage were independent prognostic factors for TCC. These results suggest that PMN-MDSCs and M-MDSCs may be involved in tumor progression and could be prognostic factors and promising therapeutic targets in dogs with TCC.

MYELOID-DERIVED SUPPRESSOR CELLS TWO YEARS AFTER HEPATITIS C VIRUS ERADICATION USING DIRECTLY ACTING ANTIVIRALS.

Myeloid-derived suppressor cells (MDSCs) have immature morphology, relatively weak phagocytic activity, as well as some immunosuppressive functions. The capacity of MDSCs to inhibit T-cell-mediated immunological responses is their most notable functional characteristic. Down-regulating antitumor immune surveillance is one way that the expansion and activation of MDSCs contribute significantly to the occurrence and progression of tumors. Increased levels of MDSCs in patients with chronic hepatitis C virus (HCV) infection could suppress T-cell responses, promoting viral escape and hepatitis progression. This may make HCV-infected individuals more vulnerable to severe infections, hepatic and extra-hepatic tumors, and a diminished capacity to react to immunization. It is still unknown if effective HCV eradication with directly acting antivirals (DAAs) can restore immune functions and immune surveillance capacity. The purpose of this study was to observe the frequency of M-MDSCs (CD33+, CD11b+, and HLA-DR) in patients with a previous history of HCV, 2-3 years after virus eradication using DAA therapy. This study was conducted on 110 subjects: fifty-five subjects without liver cirrhosis who were treated with HCV using DAAs and attained SVR for a period of 2-3 years and 55 age- and gender-matched healthy controls. The study was conducted during the period from January to July 2022. Patients were recruited from the National Viral Hepatitis Treatment Unit, Alexandria University Hepatology outpatient clinic, and the Alexandria University Tropical Medicine outpatient clinic. The frequencies of MDSCs (CD33+CD11b + HLA-DR-) by flow cytometry were assessed. Even after the virus had been eradicated for longer than two years, MDSC levels in HCV-treated individuals were found to be considerably higher. In the HCV-treated group, the median number of MDSCs was 5, with an interquartile range (IQR) of 3.79-7.69. In contrast, the median for the control group was 3.1, with an IQR of 1.4-3.2 (P˂0.001). Successful DAA therapy leads to slow and partial immunological reconstitution, as demonstrated by the failure to attain normal levels of MDSC's 2 years after successful HCV eradication despite the normalization of laboratory parameters as well as the absence of liver fibrosis. The clinical implications of these findings should be thoroughly studied.

Phenotypic Analysis of Circulating Myeloid Derived Suppressor Cells and Their Subpopulations in Egyptian Females with Breast Cancer: A Single-Centre Case-Control Study.

Myeloid-derived suppressor cells (MDSC) are immature myeloid cells with suppressive function that has been thoroughly documented in the setting of cancer. Our purpose was to evaluate levels of MDSC and their subsets in a cohort of Egyptian patients with breast cancer. Evaluation of peripheral blood total MDSC and its subset was done using multicolor flowcytometry in 30 malignant, 10 benign breast tumor patients and 10 healthy control females. BC patients had higher total MDSC levels compared to controls (p= 0.01) particularly the Monocytic MDSC (M-MDSC) and abnormal MDSC subsets (p = 0.001 and p <0.001, respectively). A tumor size > 2 cm exhibited significantly higher granulocytic MDSCs (G-MDSCs) compared to tumor size < 2 cm (p= 0.02) whereas abnormal MDSCs were significantly higher in patients with a tumor size < 2 cm (p = 0.037). MDSC and its subsets can be used as a prognostic marker of tumor size as well as a potential targets for treatment in breast cancer patients.

Mesencephalic Astrocyte-derived Neurotrophic Factor Supports Hepatitis B Virus-induced Immunotolerance

Background & AimsThe immune tolerance induced by Hepatitis B virus (HBV) is a major challenge for achieving effective viral clearance, and the mechanisms involved are not well understood. One potential factor involved in modulating immune responses is mesencephalic astrocyte-derived neurotrophic factor (MANF), which has been reported to be increased in patients with chronic hepatitis B. In this study, our objective is to examine the role of MANF in regulating immune responses to HBV. MethodsWe utilized a commonly used HBV-harboring mouse model, where mice were hydrodynamically injected with the pAAV/HBV1.2 plasmid. We assessed the HBV load by measuring the levels of various markers including HBsAg, HBeAg, HBcAg, HBV DNA, and HBV RNA. ResultsOur study revealed that following HBV infection, both myeloid cells and hepatocytes exhibited increased expression of MANF. Moreover, we observed that mice with myeloid-specific MANF knockout (ManfMye-/-) displayed reduced HBV load and improved HBV-specific T cell responses. The decreased HBV-induced tolerance in ManfMye-/- mice was associated with reduced accumulation of myeloid-derived suppressor cells (MDSCs) in the liver. Restoring MDSC levels in ManfMye-/- mice through MDSC adoptive transfer reinstated HBV-induced tolerance. Mechanistically, we found that MANF promoted MDSC expansion by activating the IL-6/STAT3 pathway. Importantly, our study demonstrated the effectiveness of a combination therapy involving an HBsAg vaccine and nanoparticle-encapsulated MANF siRNA in effectively clearing HBV in HBV-carrier mice. ConclusionThe current study reveals that MANF plays a previously unrecognized regulatory role in liver tolerance by expanding MDSCs in the liver through IL-6/ STAT3 signaling, leading to MDSC-mediated CD8+ T cell exhaustion.

EXTH-11. ADOPTIVE CELLULAR THERAPY OVERCOMES GLIOMA IMMUNE ESCAPE BY DISRUPTING MDSC PROLIFERATION AND RECRUITMENT

Abstract INTRODUCTION Our group has previously shown that adoptive cellular therapy (ACT) significantly extends survival in models of medulloblastoma, brain stem glioma, and glioblastoma. Further, ACT significantly decreases myeloid-derived suppressor cells (MDSC) in the tumor microenvironment (TME), suggesting that ACT may ameliorate glioma-mediated immunosuppression. We hypothesize that ACT-mediated reduction of MDSCs is driven by cell proliferation and recruitment mechanisms, but these mechanisms have not been defined. In this study, we quantified the proportions and cell cycle states of MDSCs in the TME and peripheral lymphoid tissues as well as chemokines in serum to determine how ACT affects MDSC recruitment. METHODS ACT was performed in C57BL/6J mice bearing a syngeneic high-grade glioma derived from KR158B-luciferase cell line. The treatment platform included total body irradiation, hematopoietic stem cell rescue, total tumor ribonucleic acid (ttRNA) electroporated dendritic cells, and tumor-reactive T cells. Following ACT completion, we evaluated the proportions and cell cycle states of MDSCs using flow cytometry. Bromodeoxyuridine (BRDU) and 7-aminoactinomycin (7-AAD) defined cell cycle phases. Serum chemokines were measured using a membrane-based sandwich immunoassay. RESULTS We replicated our previous findings that ACT reduces the level of MDSCs in the TME. Additionally, ACT significantly decreased the proportion of MDSCs in S-phase in the TME. Conversely, levels of MDSCs in peripheral lymphoid tissue were significantly increased in mice treated with ACT, with a significant increase of MDSCs in S-phase. Analysis of serum chemokines revealed significant decreases in multiple chemokines implicated in MDSC recruitment such as CXCL13 and CXCL16. CONCLUSION These findings suggest that ACT decreases proliferation and chemotactic recruitment of MDSCs to the TME, which may also explain MDSC accumulation peripheral lymphoid tissue in ACT-treated mice. These immune mechanisms likely contribute to ACT’s efficacy against brain cancer, preventing tumor immune escape, and offer new therapeutic targets for optimizing cellular immunotherapies.

Study on the Impact of G-CSF Mobilization on the Level of MDSCs in Donor Peripheral Blood and Its Correlation with Patient Prognosis

Introduction:MDSCs are a newly discovered and heterogeneous population of immature bone marrow cells with immunosuppressive characteristics, capable of inhibiting innate and adaptive immune responses. Granulocyte colony-stimulating factor (G-CSF) is a member of the hematopoietic growth factor cytokine family responsible for the proliferation, maturation, differentiation, and survival of neutrophil lineage. In many hospitals in China, allo-HSCT procedures often involve administering G-CSF continuously for 5 days to healthy donors before collecting the graft, to mobilize white blood cells. This study discusses the impact of G-CSF mobilization on the absolute values and functions of total immunosuppressive myeloid-derived suppressor cells (MDSCs) and their subsets, M-MDSCs and P-MDSCs, in the peripheral blood of healthy donors. Furthermore, it explores the effects of transferring MDSCs from the graft to the patient's body on their prognosis and immune reconstitution. Method：From August 2022 to December 2022, a total of 72 donors and 72 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) were selected as the subjects at Lu Daopei Hospital in Beijing. Among the donors, there were 47 males and 25 females, with a median age of 34 years (19, 48). Among the patients, there were 33 males and 39 females, with a median age of 34 years (23, 45). The patients were diagnosed as acute leukemia or MDS in CR status and further categorized into infection group, graft-versus-host disease (GVHD) group, and no-event group based on post-transplantation outcomes. Peripheral blood samples were collected from the donors before and on the 5th day after mobilization, as well as from the graft and the patients. Flow cytometry was employed to determine the absolute counts of MDSCs and their subsets. Result 1. The absolute count of total MDSCs in the donor's peripheral blood before mobilization was 3/μl (2, 8), accounting for 0.1% (0.0, 0.2) of PBMCs, significantly lower than the absolute count of total MDSCs in the donor's peripheral blood after G-CSF mobilization, which was 2283/μl (1091, 5288), accounting for 6.4% (3.2, 9.5) of PBMCs, P&amp;lt;0.01. In the infection group, the absolute count and percentage of total MDSCs, P-MDSCs, and LOX1+P-MDSCs in the donor's peripheral blood after mobilization were higher than those in the donor's peripheral blood corresponding to the no-event group, and significantly higher than those in the donor's peripheral blood corresponding to the GVHD group. P&amp;lt;0.05. Similarly, the absolute count and percentage of total MDSCs, P-MDSCs, and LOX1+P-MDSCs in the correspondingdonor's peripheral blood inthe infection group after mobilization were higher than those in the donor's peripheral blood corresponding to the no-event group, and significantly higher than those in the donor's peripheral blood corresponding to the GVHD group., P&amp;lt;0.05. The absolute count and percentage of M-MDSCs in the infection group were higher than the no-event group and GVHD group, but the differences among the three did not reach statistical significance. Patients who developed infections after transplantation received a higher absolute count of total MDSCs from the graft compared to the no-event group, and significantly higher than the GVHD group, P&amp;lt;0.05. The mortality rate in the infection group was 30% (8/26), in the GVHD group was 14% (3/21), and in the no-event group was 0% (0/25). The ROC curve area under the curve (AUC) for the absolute count of total MDSCs per kilogram of body weight from the donor in the GVHD group was 0.669, with a cutoff of 1.7×107/kg, while in the infection group, the AUC was 0.661, with a cutoff of 4.3×107/kg. Conclusion: G-CSF can induce an increase in the content and enhancement of function of MDSCs in the donor's peripheral blood Maintaining a balance of MDSCs helps ensure immune homeostasis after transplantation.

Clinicopathological and prognostic values of MET expression in pancreatic adenocarcinoma based on bioinformatics analysis.

Pancreatic adenocarcinoma (PAAD) is regarded as one of the most lethiferous cancers worldwide because treatment of pancreatic cancer remains challenging and mostly palliative. Little progress had been made to select certain reliable biomarkers as clinical prognosis. In this context, GSE28735 and GSE16515 were obtained from the Gene Expression Omnibus (GEO). GEO2R tool was used to recognize differentially expressed genes (DEGs). 351 DEGs were screened which included 230 up-regulated genes and 121 down-regulated genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to analyze the DEGs and associated signal pathways in the DAVID database. A protein-protein interaction (PPI) network was then constructed to screen 10 hub genes by STRING database and Cityscape software. Analyses of 10 hub genes were performed on GEPIA database and GSCA database, which revealed that MET was high expressed and significantly associated with survival of PAAD patients. Immunohistochemical staining showed that MET was higher expressed in PAAD tissues than adjacent tissues in 20 samples. The clinicopathological analysis revealed that high expression of MET was associated with the degree of differentiation, lymph node metastasis, vascular cancer thrombus and nerve invasion in PAAD tissues (P < .05). Furthermore, the Tumor Immune Estimation Resource (TIMER) database analyzed the correlation between the MET expression level and immune infiltration levels, which elucidated that MET expression was appreciably positively correlated with the infiltration levels of myeloid-derived suppressor cells (MDSCs). Here, these results strongly indicate MET is an unique prognostic biomarker. Its expression level is correlated with certain clinicopathological features and immune cell infiltration.

Targeting myeloid-derived suppressor cells with gemcitabine to enhance efficacy of adoptive cell therapy in bladder cancer.

New therapeutics in development for bladder cancer need to address the recalcitrant nature of the disease. Intravesical adoptive cell therapy (ACT) with tumor infiltrating lymphocytes (TIL) can potentially induce durable responses in bladder cancer while maximizing T cells at the tumor site. T cells infused into the bladder directly encounter immunosuppressive populations, such as myeloid derived suppressor cells (MDSCs), that can attenuate T cell responses. Intravesical instillation of gemcitabine can be used as a lymphodepleting agent to precondition the bladder microenvironment for infused T cell products. Urine samples from bladder cancer patients and healthy donors were analyzed by flow cytometry and cytometric bead array for immune profiling and cytokine quantification. MDSCs were isolated from the urine and cocultured with stimulated T cells to assess effects on proliferation. An orthotopic murine model of bladder cancer was established using the MB49-OVA cell line and immune profiling was performed. MDSCs from tumor-bearing mice were cocultured with OT-I splenocytes to assess T cell proliferation. Mice received intravesical instillation of gemcitabine and depletion of immune cells was measured via flow cytometry. Bladder tumor growth of mice treated with intravesical gemcitabine, OT-I transgenic T cells, or combination was monitored via ultrasound measurement. In comparison to healthy donors, urine specimen from bladder cancer patients show high levels of MDSCs and cytokines associated with myeloid chemotaxis, T cell chemotaxis, and inflammation. T cells isolated from healthy donors were less proliferative when cocultured with MDSCs from the urine. Orthotopic murine bladder tumors also presented with high levels of MDSCs along with enrichment of cytokines found in the patient urine samples. MDSCs isolated from spleens of tumor-bearing mice exerted suppressive effects on the proliferation of OT-I T cells. Intravesical instillation of gemcitabine reduced overall immune cells, MDSCs, and T cells in orthotopic bladder tumors. Combination treatment with gemcitabine and OT-I T cells resulted in sustained anti-tumor responses in comparison to monotherapy treatments. MDSCs are enriched within the microenvironment of bladder tumors and are suppressive to T cells. Gemcitabine can be used to lymphodeplete bladder tumors and precondition the microenvironment for intravesical ACT.