Low Myeloid-derived Suppressor Cells Research Articles

Increased CD14+HLA-DR-/low myeloid-derived suppressor cells can be regarded as a biomarker on disease severity and response to therapy in acute coronary syndrome.

This study aimed to investigate the dynamic changes in monocytic myeloid-derived suppressor cells (M-MDSCs) and their implications in the pathogenesis of acute coronary syndrome (ACS), shedding light on potential therapeutic targets. Peripheral blood samples were collected from 68 ACS patients, 35 stable angina pectoris (SAP) patients, and 30 healthy controls (HC). Multi-parameter flow cytometry was employed for analysis of M-MDSCs, explored with disease characteristics and progression. ACS patients exhibited an increased frequency of circulating M-MDSCs compared to SAP patients and HC. M-MDSCs levels demonstrated associations with ACS type, coronary artery lesions, multi-vessel disease, and cardiac dysfunction severity. Higher M-MDSCs levels were found in obese patients. Notably, therapy led to a significant decrease in M-MDSCs frequency. Furthermore, ACS patients exhibited elevated levels of interleukin (IL)-6, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-α (TNF-α) in the cytokine profile associated with M-MDSCs. Increased expression of arginase-1(Arg-1) was observed in ACS patients, with positive correlations between M-MDSCs levels and IL-6, GM-CSF, and Arg-1 expression. The diagnostic performance of triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and M-MDSCs levels varied in predicting the severity of coronary artery stenosis, with TG showing higher specificity, HDL-C displaying higher sensitivity, and M-MDSCs levels demonstrating balanced sensitivity and specificity. Assessment of M-MDSCs frequency holds promise as a predictive marker for disease progression and therapy response of coronary artery stenosis. The elevated presence of M-MDSCs suggests their potential role in modulating ACS-related inflammation.

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.

Abstract 2214: NEDD9 as a prognostic biomarker and its immune landscape in lung adenocarcinoma

Abstract Introduction: Lung adenocarcinoma (LUAD) is the deadliest cancer worldwide. Many efforts are made to search for new biomarkers to screen for immunotherapy candidates and predict the response. Neural Precursor Cell Expressed, developmentally down-Regulated 9 (NEDD9), is predominantly expressed in many cancer types but has not been studied yet in lung adenocarcinoma. Herein, we analyzed the association of NEDD9 with immune inhibitory components to understand its immune landscape in lung adenocarcinoma. Methods: Gene expression profiles were retrieved from The Cancer Genomic Atlas Lung Adenocarcinoma cohort (n = 567). We used TIMER 2.0 for immune inhibitory cell infiltrates analysis. Tumor mutational burden (TMB) was measured using the cBioPortal tool. The enrichment analysis of function and signaling pathways of DEGs in LUAD was done by gene ontology (GO) using Enrichr. Results: NEDD9 is differentially expressed in LUAD tissues (P < 0.00). High NEDD9 expression had better overall survival prognostic value in LUAD patients (HR: 0.66, 95% CI: 0.49 - 0.89, P = 0.0221) compared to low expression. NEDD9 expression was positively correlated with the infiltration of cancer-associated fibroblasts and macrophage M2 cells (spearman’s ρ = 0.257, P < 0.001, ρ = 0.266, P < 0.001, respectively), but negatively with myeloid-derived suppressor cells (MDSC) (ρ = -0.344, P < 0.001). Moreover, survival analysis based on NEDD9 expression and MDSC levels revealed a better OS group identified by low MDSC levels and low NEDD9 expression after adjustment for age, stage, and purity. In terms of immune checkpoint genes’ expression, NEDD9 expression was directly correlated with CTLA-4, PD-1, PD-L1, VSIR, and LAG-3 (ρ > 0.2, Q value < 0.05). TMB was inversely associated with NEDD9 expression (ρ = -0.1, P < 0.001). GO analysis showed that genes co-expressed with NEDD9 were mainly in the phagocytic vesicles and participated in biological processes of cellular response to interferon-gamma by molecular function such as cysteine-type endopeptidase activity involved in apoptotic signaling pathways. Conclusion: We found that NEDD9 expression is a useful biomarker of immunosuppression in LUAD patients and can predict the response to immunotherapy. Our results suggest that NEDD9 is a favorable prognostic biomarker, which could be explained by low MDSC. Further studies are needed for a better understanding of the NEDD9 value in LAUD. Citation Format: Leen M. Al-Kraimeen, Yaqeen M. Al-Kraimeen. NEDD9 as a prognostic biomarker and its immune landscape in lung adenocarcinoma [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 2214.

Leukocyte subtypes and myeloid derived suppressor cells as prognostic markers in metastatic castration resistant prostate cancer treated with cabazitaxel: A satellite study of the CABASTY phase III trial.

126 Background: CABASTY trial investigated the benefit of an adapted schedule of cabazitaxel (16 mg/m2 bi-weekly versus 25 mg/m2 tri-weekly) in mCRPC patients previously treated with docetaxel and alternative androgen-targeted therapy. The study met its endpoints with a significantly decreased incidence of grade ≥ 3 neutropenia without a decrease in overall survival. This preplanned analysis evaluated the prognostic impact of neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-platelets ratio (NPR) myeloid derived suppressor cells (MDSC) and leukocyte subtypes counts in this setting. Methods: 44 patients treated with cabazitaxel were included. Peripheral blood mononuclear cells were isolated and myeloid compartment analysis were performed at baseline, week 6 (S6) and week 12 (S12) of treatment using a multi-parametric flow cytometry panel. We investigated at each timepoints the association of NPR, NLR, MDSC and leukocytes subtypes with PSA response rate (PSArr), Progression Free Survival, and Overall Survival with a preplanned uni- and multivariate analysis. Results: The NLR, NPR, MDSC subtypes and lymphocytes count at baseline were prognostic in the CABASTY trial regardless of the cabazitaxel regimen. Patients with a high lymphocyte count and/or a low NLR, NPR, and MDSC counts at baseline had a significantly improved PSAr, PFS and OS. In the multivariate analysis, a NPR > 1,84 and lymphocytes count < 1,2 G/L at baseline were significantly associated with OS [HR 2.007 (1.3 - 3.1)] and [HR 0.38 (0.20 - 0.73)]. Conclusions: High NLR, NPR, neutrophil and MDSC counts as well as a low lymphocyte count at baseline and during treatment predict poor outcomes in mCRPC patients treated with cabazitaxel. NPR and lymphocyte count are readily available biomarkers that may be useful for risk stratification in future clinical trials and could be incorporated into prognostic nomograms. Clinical trial information: NCT02961257 .

Splenic and PB immune recovery in neoadjuvant treated gastrointestinal cancer patients

In recent years, immune therapy, notably immune checkpoint inhibitors (ICI), in conjunction with chemotherapy and surgery has demonstrated therapeutic activity for some tumor types. However, little is known about the optimal combination of immune therapy with standard of care therapies and approaches. In patients with gastrointestinal (GI) cancers, especially pancreatic ductal adenocarcinoma (PDAC), preoperative (neoadjuvant) chemotherapy has increased the number of patients who can undergo surgery and improved their responses. However, most chemotherapy is immunosuppressive, and few studies have examined the impact of neoadjuvant chemotherapy (NCT) on patient immunity and/or the optimal combination of chemotherapy with immune therapy. Furthermore, the majority of chemo/immunotherapy studies focused on immune regulation in cancer patients have focused on postoperative (adjuvant) chemotherapy and are limited to peripheral blood (PB) and occasionally tumor infiltrating lymphocytes (TILs); representing a minority of immune cells in the host. Our previous studies examined the phenotype and frequencies of myeloid and lymphoid cells in the PB and spleens of GI cancer patients, independent of chemotherapy regimen. These results led us to question the impact of NCT on host immunity. We report herein, unique studies examining the splenic and PB phenotypes, frequencies, and numbers of myeloid and lymphoid cell populations in NCT treated GI cancer patients, as compared to treatment naïve cancer patients and patients with benign GI tumors at surgery. Overall, we noted limited immunological differences in patients 6 weeks following NCT (at surgery), as compared to treatment naive patients, supporting rapid immune normalization. We observed that NCT patients had a lower myeloid derived suppressor cells (MDSCs) frequency in the spleen, but not the PB, as compared to treatment naive cancer patients and patients with benign GI tumors. Further, NCT patients had a higher splenic and PB frequency of CD4+ T-cells, and checkpoint protein expression, as compared to untreated, cancer patients and patients with benign GI tumors. Interestingly, in NCT treated cancer patients the frequency of mature (CD45RO+) CD4+ and CD8+ T-cells in the PB and spleens was higher than in treatment naive patients. These differences may also be associated, in part with patient stage, tumor grade, and/or NCT treatment regimen. In summary, the phenotypic profile of leukocytes at the time of surgery, approximately 6 weeks following NCT treatment in GI cancer patients, are similar to treatment naive GI cancer patients (i.e., patients who receive adjuvant therapy); suggesting that NCT may not limit the response to immune intervention and may improve tumor responses due to the lower splenic frequency of MDSCs and higher frequency of mature T-cells.

Tim-4 expressing monocytes as a novel indicator to assess disease activity and severity of ulcerative colitis

AimsThe dysregulation of the immune response has been shown to be involved in ulcerative colitis (UC) pathogenesis. Tim-4 is a potential regulator of the immune system which plays key roles in multiple autoimmune diseases. However, whether it is involved in UC remains unclear. The aim of this research was to determine the expression of Tim-4 on circulating monocytes and its clinical significance in UC patients. Main methodsIn total, 36 UC patients and 34 healthy controls (HCs) were enrolled in this study. The frequencies of CD14+Tim-4+ cells, regulatory T cells (Treg) and CD14+HLA-DR−/low myeloid-derived suppressor cells (MDSCs) in the peripheral blood were determined by flow cytometry. Serum IL-6 levels were determined by chemiluminescence immunoassay. Key findingsThe percentage of CD14+Tim-4+ cells was higher in UC patients than in HCs. The frequency of Treg cells was significantly decreased, while that of MDSCs was significantly increased in UC patients. The frequency of CD14+Tim-4+ cells was significantly elevated in subjects with high severity, high number of defecations per day, high UC disease activity index Mayo score, high IgG, and high levels of inflammatory markers. And the percentages of Tim-4-expressing monocytes were significantly decreased in UC patients that received a 3-week treatment with mesalazine. Furthermore, the frequency of CD14+Tim-4+ cells was also positively correlated with MDSCs and negatively correlated with Treg cells. SignificanceCD14+Tim-4+ cells was elevated in UC patients and could be a novel indicator to assess disease severity and activity of UC.

Immune function of myeloid-derived suppressor cells and its mechanism in obstructive sleep apnea syndrome

Objective: To investigate the immune function of myeloid-derived suppressor cells (MDSC) and its mechanism in obstructive sleep apnea syndrome (OSAS). Methods: Twenty OSAS patients who were diagnosed by polysomnography (Apnea Hyponea Index>30 events/h) from Sleep Disorders Center at First Affiliated Hospital between January 2015 and December 2016 were selected. The percent of CD14(+) low expression or lack of human leukocyte antigen DR (HLA-DR(-/low)) MDSC in the CD14(+) monocyte from both OSAS patients and healthy people were analyzed by flow cytometry. In vitro assay, MDSC from OSAS patients and health people were sorted by flow cytometry and T cells were sorted with negative isolation kit. For T-cell proliferation assays, the carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled T cells were respectively incubated with autologous MDSC. CFSE fluorescence intensity of T cells was detected by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) and Western blot analysis were used to evaluate the concentrations of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), IL-10, transforming growth factor-β(1) (TGF-β(1)), positive rate of programmed death ligand-L1 (PD-L1), relative transcript level of Arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), hypoxic inducible factor-1α (HIF-1α) expressed by MDSC. Results: Comparing to healthy people, the percentage of CD14(+)HLA-DR(-/low) MDSC in CD14(+) monocyte was significantly elevated [(12.5±1.5)% vs (3.5±0.4)%, P<0.05]. In vitro, OSAS patient-derived MDSC exhibited a stronger suppressive effect on T-cell proliferation [(23.2±1.1)% vs (53.7±3.2)%, P<0.05]. Further analysis revealed that OSAS patient-derived MDSC secreted much higher concentrations of IL-6, TNF-α, IL-10 and TGF-β(1) [(1 316±163) vs (642±72) ng/L, (316±35) vs (167±18) ng/L, (385±42) vs (108±26) ng/L and (44 276±4 589) vs (9 557±1 124) ng/L] (all P<0.05). The percentage of membrane molecule PD-L1-positive cells in OSAS patient-derived MDSC was obviously higher than that in healthy people-derived MDSC [(75.6±7.9)% vs (30.6±2.5)%, P<0.05]. Compared with healthy people-derived MDSC, the relative transcript level of Arg1, iNOS and HIF-1α in OSAS patient-derived MDSC was also increased by (4.6±0.5), (2.8±0.3) and (4.3±0.4) fold, respectively (all P<0.05). Conclusions: OSAS may be capable of inducing the proliferation of MDSC and its expression of immunosuppressive molecules by activating HIF-1α signal, thereby enhancing the immunosuppressive ability of MDSC.

Myeloid-Derived Suppressor Cells Show Different Frequencies in Diabetics and Subjects with Arterial Hypertension.

Type 2 diabetes mellitus (DM2) is strongly associated with other comorbidities such as obesity, atherosclerosis, and hypertension. Obesity is associated with sustained low-grade inflammatory response due to the production of proinflammatory cytokines. This inflammatory process promotes the differentiation of some myeloid cells, including myeloid-derived suppressor cells (MDSCs). In this study, two groups of individuals were included: DM2 patients and non-DM2 individuals with similar characteristics. Immunolabeling of CD15+ CD14- and CD33+ HLA-DR-/low was performed from whole peripheral blood, and samples were analyzed by flow cytometry, and frequencies of MDSCs and the relationship of these with clinical variables, cytokine profile (measured by cytometric bead array), and anthropometric variables were analyzed. The frequency of CD33+ HLA-DR-/low MDSCs (that produce IL-10 and TGF-β, according to an intracellular detection) is higher in patients with DM2 (P < 0.05), and there is a positive correlation between the frequency of CD15+ CD14- and CD33+ HLA-DR-/low MDSC phenotypes. DM2 patients have an increased concentration of serum IL-5 (P < 0.05). Also, a negative correlation between the frequency of CD15+ CD14- MDSCs and LDL cholesterol was found. Our group of DM2 patients have an increased frequency of mononuclear MDSC CD33+ HLA-DR-/low that produce TGF-β and IL-10. These cytokines have been associated with immune modulation and reduced T cell responses. DM2 and non-DM2 subjects show a similar cytokine profile, but the DM2 patients have an increased concentration of IL-5.

The mechanism of the premetastatic niche facilitating colorectal cancer liver metastasis generated from myeloid-derived suppressor cells induced by the S1PR1\u2013STAT3 signaling pathway

The tumor-derived factors involved in the expansion and accumulation of myeloid-derived suppressor cells (MDSCs) in metastatic dissemination of colorectal cancer (CRC) to the liver has not been studied. Immunohistochemistry was used to detect sphingosine-1-phosphate receptor 1 (S1PR1) and signal transducer and activator of transcription-3 (STAT3) in human colorectal tumors. IL-6 and interferon-γ were detected by enzyme-linked immunosorbent assay (ELISA). Tumor growth, invasion, and migration were evaluated by MTT, transwell, and wound healing assays, respectively. Subcutaneous tumor-bearing and CRC liver metastasis (CRLM) nude mouse models were constructed. The percentage of MDSCs was measured using multicolor flow cytometry. Western blot assay was used to evaluate S1PR1 and p-STAT3 expression in MDSCs after separation from the liver and tumor by magnetic antibody. T-cell suppression assay was detected by carboxyfluorescein succinimidyl ester (CFSE). Aberrant co-expressed S1PR1 and p-STAT3 was correlated with metachronous liver metastasis and poor prognosis in CRC. A mutual activation loop between S1PR1 and STAT3 can enhance CRC cell proliferation, migration, and invasion in vitro and in vivo. The expression of p-STAT3 and its downstream proteins can be regulated by S1PR1. p-STAT3 was the dependent signaling pathway of S1PR1 in the promotion of cell growth and liver metastasis in CRC. The level of IL-6 and the associated MDSCs stimulated by the S1PR1–STAT3 correlated with the number of liver metastatic nodes in the CRLM mouse models and patients. Increased CD14+HLA-DR−/low MDSCs from CRLM patients inhibited autologous T-cell proliferation and predict poor prognosis. The S1PR1–STAT3–IL-6–MDSCs axis operates in both tumor cells and MDSCs involved in the promotion of growth and liver metastasis in CRC. MDSCs induced by S1PR1–STAT3 in CRC cells formed the premetastatic niche in the liver can promote organ-specific metastasis.

Myeloid Derived Suppressor Cells Expansion Persists After Early ART and May Affect CD4 T Cell Recovery

Myeloid-derived suppressor cells (MDSC) are expanded during HIV-1 infection and correlated with disease progression. MDSC expand in the early phase of primary infection depending on TRAIL level. In this study we evaluated the effect of ART on the frequency of MDSC in patients with primary HIV infection (PHI), and their impact on CD4 T cell reconstitution. MDSC frequency was evaluated by flow-cytometry in 60 PHI patients at 12, 24 and 48 weeks after ART initiation. Cytokine plasma levels were evaluated by Luminex technology at the same time points. The capacity of MDSC to modulate hematopoietic early progenitor cells' expansion was evaluated using the OP9/Dl1 in vitro system. As previously described, polymorphonuclear-MDSC (PMN-MDSC) frequency was higher in PHI compared to healthy donors. Interestingly, 48 weeks of successful ART failed to normalize the PMN-MDSC frequency. Moreover, PMN-MDSC frequency was not correlated with residual viral load, suggesting that the persistence of PMN-MDSC was not due to residual viral replication. Interestingly, patients with low PMN-MDSC frequency (<6%) at T0 had a higher HIV DNA at the same time point than individuals with high PMN-MDSC frequency (>6%). We also found an inverse correlation between PMN-MDSC frequency and CD4-T cell count at 48 weeks post-ART, which was confirmed by multivariate analysis adjusting for age and CD4 T cell number at baseline. These data suggest that the persistence of PMN-MDSC may impact CD4 T cell recovery. Indeed, in vitro PMN-MDSC impaired the expansion of CD34+CD38- hematopoietic early progenitors. Further, a balance between TRAIL and GM-CSF may be necessary to maintain a low MDSC level. In conclusion, early ART initiation was not able to normalize PMN-MDSC frequency that might impact the CD4 T cell recovery. These data open new questions regarding the clinical impact of MDSC persistence in HIV+ patients, in particular on non-AIDS related diseases.

Increased CD14+HLA-DR-/low Myeloid-Derived Suppressor Cells Correlate With Disease Severity in Systemic Lupus Erythematosus Patients in an iNOS-Dependent Manner.

Myeloid-derived suppressor cells (MDSCs) comprise of a population of cells, which suppress the innate and adaptive immune system via different mechanisms. MDSCs are accumulated under pathological conditions. The present study aimed to clarify the pathological role of MDSCs in systemic lupus erythematosus (SLE) patients. Consequently, the level of circulating M-MDSCs was significantly increased in newly diagnosed SLE patients as compared to healthy controls. An elevated level of M-MDSCs was positively correlated with the disease severity in SLE patients and an immunosuppressive role was exerted in an iNOS-dependent manner. The decrease in the number of M-MDSCs after therapy rendered them as an indicator for the efficacy of treatment. These results demonstrated that M-MDSCs participated in the pathological progress in SLE patients. Thus, MDSCs are attractive biomarkers and therapeutic targets for SLE patients.

Correlation of immune-related adverse events with peripheral baseline immune markers and overall survival in patients with metastatic melanoma on ipilimumab and chemotherapy.

9561 Background: Very few predictive markers have been validated for immune-related adverse events (irAE), which are the number one reason for cessation of treatment and treatment-related deaths on checkpoint inhibitors. In a phase II trial of combined ipilimumab (ipi) with carboplatin/paclitaxel (C/P) (NCT01676649), we sought to determine baseline peripheral blood markers predictive of irAEs and to correlate these adverse with subsequent survival. Methods: Thirty patients with untreated unresectable/metastatic melanoma were treated with C (AUC = 6) and P (175mg/m2) every 3 weeks x 5 and Ipi (3mg/kg) every 3 weeks x 4. irAEs were graded according to the CTCAE v5.0. Median follow-up was 60 months. Baseline blood markers was assessed by a 37 multiplex cytokine-chemokine platform (Meso Scale Discovery) and multiparameter flow cytometry. Results: Grade 2 or higher irAE occurred in 11/30 of patients (4 colitis, 2 hepatitis, 2 hypophysitis, 3 rash). Median survival was 43.8 months in patients with irAE and 14.5 months for those without irAE (p = 0.001). Pts with irAE had lower baseline circulating levels of IL-6 (3.6 vs. 19.8 pg/mL, p = 0.049), TNF alpha (7.6 vs. 11.6 pg/mL, p = 0.003), CXCL9 (83.4 vs. 116.8 pg/mL, p = 0.042) and CCL3 (52.3 vs. 76.4 pg/mL, p = 0.012), but higher baseline circulating dendritic cells (DC) (4.9 vs. 2.9 % of total PBMC, p = 0.002) and a lower level of myeloid-derived suppressor cells (MDSC) (0.8 vs. 1.7 %, p = 0.049). There was no correlation between baseline B cell circulating numbers or differentiation and irAEs. Conclusions: Although results from previous studies of ipi monotherapy vary, our small study shows a highly significant correlation between irAEs and improved long term outcome for patients treated with ipi/C/P. Our exploratory analysis also identifies putative predictive immune and cytokine-chemokine markers of irAEs, which are associated with: 1) Antigen presentation dysregulation (high DC cells) and lack of adequate auto-immune suppression (low MDSC), as also seen in classic autoimmune diseases; and 2) A low inflammatory baseline signature (low TNF, IL-6, CCL3, CXCL9) consistent with possible immune exhaustion and reduced lymphocytic homeostatic fitness. Our combined markers depict a dysregulated immune landscape favorable to the expansion of self-reactive immune cells under CTLA-4 blockade. Our results are hypothesis generating and require further evaluation in a larger group of patients, including PD-1 treated cohorts. Clinical trial information: NCT01676649.

Correlation of inflammation-related markers with MDSC and IL-17, and use as prognostic indicators in patients with advanced gastric and colorectal cancers.

e14204 Background: Although a causal relationship for inflammation and immunity of cancer is more widely accepted today, the precise cell mechanisms mediating this relationship have not been elucidated. Accumulating evidence suggests that myeloid-derived suppressor cells (MDSC), may contribute to the negative regulation of immune responses during cancer and inflammation. IL-17 is a pro-inflammatory cytokine that is primarily secreted by T helper (Th)17 cells and we have reported that IL-17 correlates with immunosuppressive conditions in patients with cancer. Methods: PBMC (peripheral blood mononuclear cells) were harvested from 106 patients including 43 with gastric and 63 with colorectal cancer. PBMC were stimulated with PHA (phytohemagglutinin) and the production of IL-17 was measured by ELISA. MDSC were detected by flow cytometry (CD11b+,CD14-,CD33+). The levels of CRP (C-reacting protein) and NLR (neutrophil to lymphocyte ratio) were used as inflammatory markers. Results: Both of MDSC and IL-17 production were increased in patients with advanced stages, and correlated with each other, inflammatory markers and immune suppression. The patients were divided with average levels of MDSC and IL-17 production and the prognosis were analyzed with Kaplan-Meier method. The overall survival of patients with high MDSC or high IL-17 production were significantly worse than those with low MDSC or low IL-17 production, respectively, in patients with stages III and IV, although the differences were not significant in patients with stages I and II. Conclusions: Thus these inflammatory markers are closely related with systemic inflammation involving IL-17 and with immunosuppression driven by MDSC, and are effective prognostic indicators in patients with stages III and IV gastric and colorectal cancer.

Myeloid-derived suppressor cells expansion is closely associated with disease severity and progression in HBV-related acute-on-chronic liver failure.

Dysregulation of the host immune responses induced by host hepatitis B virus (HBV) interactions has been observed in acute-on-chronic liver failure (ACLF). Myeloid-derived suppressor cells (MDSCs), well known for their immunomodulatory properties, can suppress T-cell function by regulating the expression of CD3 ζ chain in cancer and autoimmune/infectious diseases while rarely have been studied in ACLF. In this study, MDSCs, CD4+ /CD8+ T cells, and CD3 ζ chain were analyzed by flow cytometry in peripheral blood mononuclear cells obtained from HBV-related ACLF patients, chronic hepatitis B (CHB) patients and healthy controls. ACLF patients were followed up for dynamic detection of MDSCs and observation of outcomes after treatment. Interestingly, peripheral CD14+ CD33+ CD11b+ HLA-DR-/low MDSCs from ACLF patients were significantly increased compared to those from CHB patients and healthy controls. CD4+ /CD8+ T cell frequency and CD3 ζ chain expression in T cells were decreased in ACLF patients compared to those of healthy controls and were negatively correlated with matched MDSC frequency. Meanwhile, the frequency of MDSCs was closely correlated with biochemical parameters that are relevant for liver injury rather than virological parameters. Moreover, a lower level of MDSCs was correlated with a better short-term prognosis (within 4 weeks but not at 8 weeks), and MDSCs remained high in ACLF patients whose conditions worsened within a 4-week follow-up period after treatment. These results suggest that MDSCs are closely involved in cell-mediated immunity in HBV-related ACLF and that peripheral MDSC expansion is closely associated with disease severity and progression in HBV-related ACLF, which may serve as a predictor of short-term prognosis.

Abstract B139: Plant viral particle vaccine induces a potent antitumor response through induction of antigen-specific T-cells and overcoming an immunosuppressive tumor microenvironment

Abstract In order to develop an effective vaccination strategy for cancer, it is necessary to induce robust T-cell responses and to overcome the immunosuppressive tumor microenvironment (TME). To induce anticancer immunity, we focused on a plant viral particle (PVP) that contains-single strand RNA (ssRNA) as a flexible and economical platform to deliver cancer antigens. Initially using PVP loaded with SIINFEKL, we demonstrated the induction of a rapid CD8 T-cell response leading to a significant therapeutic effect in the B16 tumor model. The induction of high levels of CD8 T-cells was also achieved when clinically relevant cancer antigens were used with lysis of human cancer cells expressing these antigens. Further, PVP loaded with whole protein antigen induced CD8 and CD4 T-cell responses against the epitopes delivered through the whole antigen and these cleared established tumors. The mechanisms behind the high immunogenicity of the PVP vaccine revealed that this ssRNA containing vaccine activated the immune mechanisms closely resembling the natural antiviral defence. In a murine model, the immune induction was through the activation of TLR7, leading to release of type I IFN by plasmacytoid dendritic cells and activation of conventional DCs (cDCs) followed with the priming of Th1 immunity. These findings were further supported by experiments using human monocytes derived DCs (moDCs) stimulated in vitro with PVP. The stimulated moDCs released Th1-polarizing cytokines and chemokines, and upregulated CD40 and B7 family surface molecules. Further investigation of the TME demonstrated that cDCs, MHC-II high tumor associated macrophages (TAMs) and tumor-infiltrating neutrophils were recruited into the tumor bed 24 hours after vaccination. While MHC-II low TAMs and myeloid-derived suppressor cells were down-regulated in response to vaccination. This was followed by the increase of tumor-infiltrating lymphocytes (TILs) specific for endogenous tumor antigens. In conclusion, the PVP vaccine is an effective platform to induce T-cells specific to the delivered cancer antigens, and furthermore benefit from its ability to convert an immunosuppressive TME towards an immunostimulatory environment, facilitating the endogenous T-cell epitopes spread. Citation Format: Chuan Wang, Yidao Wang, Alex J. Allen, Jantipa Jobsri, Gareth J. Thomas, Christian H. Ottensmeier, Natalia Savelyeva. Plant viral particle vaccine induces a potent antitumor response through induction of antigen-specific T-cells and overcoming an immunosuppressive tumor microenvironment [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B139.

Targeting the crosstalk between cytokine-induced killer cells and myeloid-derived suppressor cells in hepatocellular carcinoma

Cytokine-induced killer (CIK) cell-based immunotherapy is effective as an adjuvant therapy in early stage hepatocellular carcinoma (HCC) but lacks efficacy in advanced HCC. We aimed to investigate immune suppressor mechanisms in HCC, focusing on the role of myeloid-derived suppressor cells (MDSCs) in response to CIK therapy. MDSCs were quantified by flow cytometry and quantitative real-time PCR. Cytokines were detected by cytokine array. A lactate dehydrogenase cytotoxicity assay was performed in the presence or absence of MDSCs to study CIK function against HCC cells in vitro. An FDA-approved PDE5 inhibitor, tadalafil, was used to target MDSCs in vitro and in vivo. Two different murine HCC cell lines were tested in subcutaneous and orthotopic tumor models in C57BL/6 and BALB/c mice. The antitumor effects of human CIKs and MDSCs were also tested in vitro. Adoptive cell transfer of CIKs into tumor-bearing mice induced inflammatory mediators (e.g., CX3CL1, IL-13) in the tumor microenvironment and an increase of tumor-infiltrating MDSCs, leading to impaired antitumor activity in 2 different HCC models. MDSCs efficiently suppressed the cytotoxic activity of CIKs in vitro. In contrast, treatment with a PDE5 inhibitor reversed the MDSC suppressor function via ARG1 and iNOS blockade and systemic treatment with a PDE5 inhibitor prevented MDSC accumulation in the tumor microenvironment upon CIK cell therapy and increased its antitumor efficacy. Similar results were observed when human CIKs were tested in vitro in the presence of CD14+HLA-DR-/low MDSCs. Treatment of MDSCs with a PDE5 inhibitor suppressed MDSC suppressor function and enhanced CIK activity against human HCC cell lines in vitro. Our results suggest that targeting MDSCs is an efficient strategy to enhance the antitumor efficacy of CIKs for the treatment of patients with HCC. Cytokine-induced killer cells are a mixture of immune cells given to eliminate cancer cells. However, not all patients respond to this treatment. Herein, we show in 2 different liver cancer models that myeloid-derived suppressor cells are increased in response to cytokine-induced killer cell therapy. Targeting these myeloid-derived suppressor cells may provide an additional therapeutic benefit alongside cytokine-induced killer cell therapy.

Histamine targets myeloid-derived suppressor cells and improves the anti-tumor efficacy of PD-1/PD-L1 checkpoint blockade

Myeloid-derived suppressor cells (MDSCs) are immature monocytes and granulocytes that impede immune-mediated clearance of malignant cells by multiple mechanisms, including the formation of immunosuppressive reactive oxygen species (ROS) via the myeloid cell NADPH oxidase (NOX2). Histamine dihydrochloride (HDC), a NOX2 inhibitor, exerts anti-cancer efficacy in experimental tumor models but the detailed mechanisms are insufficiently understood. To determine effects of HDC on the MDSC compartment we utilized three murine cancer models known to entail accumulation of MDSC, i.e. EL-4 lymphoma, MC-38 colorectal carcinoma, and 4T1 mammary carcinoma. In vivo treatment with HDC delayed EL-4 and 4T1 tumor growth and reduced the ROS formation by intratumoral MDSCs. HDC treatment of EL-4 bearing mice also reduced the accumulation of intratumoral MDSCs and reduced MDSC-induced suppression of T cells ex vivo. Experiments using GR1-depleted and Nox2 knock out mice supported that the anti-tumor efficacy of HDC required presence of NOX2+ GR1+ cells in vivo. In addition, treatment with HDC enhanced the anti-tumor efficacy of programmed cell death receptor 1 (PD-1) and PD-1 ligand checkpoint blockade in EL-4- and MC-38-bearing mice. Immunomodulatory effects of a HDC-containing regimen on MDSCs were further analyzed in a phase IV trial (Re:Mission Trial, ClinicalTrials.gov; NCT01347996) where patients with acute myeloid leukemia received HDC in conjunction with low-dose IL-2 (HDC/IL-2) for relapse prevention. Peripheral CD14+HLA-DR−/low MDSCs (M-MDSCs) were reduced during cycles of HDC/IL-2 therapy and a pronounced reduction of M-MDSCs during HDC/IL-2 treatment heralded favorable clinical outcome. We propose that anti-tumor properties of HDC may comprise the targeting of MDSCs.

Long term impact of CTLA4 blockade immunotherapy on regulatory and effector immune responses in patients with melanoma

BackgroundWe previously reported early on-treatment significant modulation in circulating regulatory T cell (Treg), myeloid derived suppressor cells (MDSC) and antigen-specific type I CD4+ and CD8+ T cells that correlated with clinical outcome in regionally advanced melanoma patients treated with neoadjuvant ipilimumab. Here, we investigated the long term immunologic impact of CTLA4 blockade.MethodsPatients were treated with ipilimumab given at 10 mg/kg IV every 3 weeks for 2 doses bracketing surgery. Blood specimens were collected at baseline and during treatment for up to 9 months. We tested immune responses at 3, 6, and 9 months utilizing multicolor flow cytometry. We compared frequencies of circulating Treg and MDSC on-study to baseline levels, as well as frequencies of CD4+ and CD8+ T cells specific to shared tumor-associated antigens (Gp-100, MART-1, NY-ESO-1).ResultsLevels of Treg significantly increased when measured at 6 weeks following ipilimumab but returned to baseline by 3 months, with no significant difference in Treg levels between relapsed and relapse-free groups at 3, 6 or 9 months. However, lower baseline levels of circulating Treg (CD4+CD25hi+CD39+) were significantly associated with better relapse free survival (RFS) (p = 0.04). Levels of circulating monocytic HLA-DR+/loCD14+ MDSC were lower at baseline in the relapse-free group and further decreased at 6 weeks, though the differences did not reach statistical significance including measurements at 3, 6 or 9 months. We detected evidence of type I (interferon-γ producing), activated (CD69+) CD4+ and CD8+ antigen-specific T cell immunity against cancer-testis (NY-ESO-1) as well as melanocytic lineage (MART-1, gp100) antigens in the absence of therapeutic vaccination. These responses were significantly boosted at 6 weeks and persisted at 3, 6 and 9 months following the initiation of ipilimumab.ConclusionsLower Treg levels at baseline are significantly associated with RFS and increased Treg frequency after CTLA4 blockade was only transient. Lower MDSC was also associated with RFS and MDSC levels were further decreased after ipilimumab. Tumor specific effector immune responses are boosted with CTLA4 blockade and tend to be durable.Trial registration ClinicalTrials.gov Identifier: NCT00972933

Dynamics of CD25 Positive Myeloid Derived Suppressor Cells in Solid Organ Transplanted Patients and Relationship with Rejection

Backgound Myeloid derived suppressor cells (MDSC) are immature cells with immunosuppressive capacities. Three MDSC subsets are currently defined: monocytic, early stage, and polymorphonuclear MDSC (M-MDSC, eMDSC and PMN-MDSC respectively). While MDSC increase in cancer and chronic infections and associate with poor prognosis, their role in transplantation (Tx) is unknown. Changes in MDSC in transplant patients could provide biomarkers of graft evolution, and they could be useful as immunosuppressive therapy and/or to stimulate the allograft tolerance. Methods Peripheral blood MDSC were identified in cohorts of kidney (n=164) and liver (n=30) recipients and healthy volunteers (HV) as CD33+CD11b+HLA-DRlo/-. We characterized CD14+CD15- (M-MDSC) and CD14-CD15- (eMDSC) subsets. Suppression assays and measurement of surface CD25 expression (MFI) on MDSC were performed. Results Renal recipients MDSC were able to suppress CD4 and CD8 T cell proliferation in vitro. MDSC % were similar in pre-transplant, kidney transplant recipients (KTR), than in HV. However, MDSC and M-MDSC increased, mainly at 7 and 14 days post-transplant (3.48% and 3.85% vs 1.14%; 2.47% and 2.48% vs 0.24% p≤0,001 vs pre-transplant). The increase of MDSC in KTR with basiliximab as induction therapy was lower than in patients induced with thymoglobulin or without induction, and eMDSC were particularly decreased in basiliximab-treated patients (vs no induction, p≤0.05; vs thymoglobulin, p≤0.05). We confirmed that eMDSC expressed CD25, target of basiliximab. Pre-Tx, liver transplant recipients (LTR) had higher % of CD25+ eMDSC and higher CD25 MFI than KTR and HV. In LTR and KTR without basiliximab, % and MFI of CD25 in eMDSC increased after transplant. In KTR cohort, 7% of patients suffered acute rejection (AR). Absolute numbers of MDSC at 7 days post-transplant (measured before the rejection event) were significantly lower in AR than in non-rejectors (25.84 cells/uL vs 53.18 cells/uL respectively, p≤0,05). Conclusions MDSC and M-MDSC increase post-Tx except in patients receiving basiliximab. MDSC were lower in AR patients and low MDSC counts significantly preceded rejection. Transplant recipients eMDSC express CD25 which upregulates after Tx. Whether eMDSC express a complete and functional IL-2R is under investigation.

Prognostic value of tumor infiltration immune cells in pancreatic cancer

Objective: To investigate the prognostic effect of tumour-infiltrating immune cell, including CD8(+) T cell, regulatory T-cell (Treg) and myeloid-derived suppressor cells (MDSC) on pancreatic patients. Methods: This study retrospectively collected the data of 80 patients who were histologically diagnosed of pancreatic cancer and underwent classical R0 surgical resection at Tianjin Medical University Cancer Institute and Hospital from January 2010 to May 2012. All patients survival were followed up until the cut-off date of January 2015. Clinicopathological features including immunohistochemical staining of FOXP3, CD8 and CD33 were reviewed as indice for evaluating the prognosis of pancreatic patients.The prognostic effect of tumour-infiltrating immune cells were analysed by Kaplan-Meier and Log-rank test. Multiple-factor analysis was conducted with the Cox regression model. The correlation between tumour-infiltrating immune cells and clinicopathological features was analysed by χ(2) test. The C57BL/6 mouse model was used to evaluate the efficacy of Treg and MDSC depletion therapy in vivo. Student's t-test was applied to assess the difference of the tumour volume, Ki-67 positive rate and CD8(+) T-cell infiltration proportion between depletion group and control group. Results: Eventually, 80 patients were included and no patient was lost during the follow-up period. The median follow-up time was 33.2 months (7.4-59.9 months). Patients with high level of tumour-infiltrating CD8(+) T cells had longer overall survival (OS) time ((21.6±11.9)months vs. (13.6±7.4)months, χ(2)=4.647, P = 0.031) than those with low level of tumour-infiltrating CD8(+) T cells. Tumor infiltration FOXP3(+) cells were strongly associated with reduced OS((20.9±8.5)months vs.(13.4±8.8)months, χ(2)=10.528, P=0.001), reduced relapse free survival (RFS) ((15.2±9.0)months vs. (9.5±8.8)months, χ(2)=6.288, P=0.012) and larger tumor size(χ(2)=4.073, r=0.226, P=0.044). The high intratumoural MDSC group showed a significantly shorter OS((23.5±11.8)months vs. (13.8±7.6)months, χ(2)=5.724, P=0.017), RFS((17.9±11.3)months vs. (10.2±7.5)months, χ(2)=7.430, P=0.006) and more advanced N stage (χ(2)=4.714, r=0.243, P=0.030) than the low intratumoural MDSC group. Multivariate Cox analysis revealed that pTNM (P=0.008), tumour-infiltrating Treg density (P=0.009) and intratumoural MDSC density (P=0.034) were independent and negative prognostic factors for OS; pTNM(P=0.003) and tumour-infiltrating MDSC level(P=0.018) were independent and negative factors for RFS. The experiment in vivo revealed that Treg and MDSC depletion therapy significantly decreased tumour volume in the C57BL/6 mouse model of subcutaneous tumours((1 396.3±442.5)mm(3) vs. (3 356.9±533.5)mm(3), t=4.986, P=0.018). Tumour Ki-67 positive rate significantly decreased (23%±5% vs. 55%±10%, t=3.130, P=0.011) in Treg and MDSC depletion group, whereas, the proportion of tumour-infiltrating CD8(+) T cells significantly increased in depletion groups (3.25%±0.69% vs. 0.76%±0.25%, t=3.393, P=0.007). Conclusions: Tumour-infiltrating Treg, MDSC level and pTNM stage are independent prognostic factors for patients with pancreatic cancer. Treg and MDSC depletion therapy can significantly retard tumour growth and increase the level of tumour-infiltrating CD8(+) T-cells in the C57BL/6 mouse model of subcutaneous tumours.