Myeloid-derived Suppressor Cells In Peripheral Blood Research Articles

Prognostic Significance of PD-L1 Expression on Circulating Myeloid-Derived Suppressor Cells in NSCLC Patients Treated with Anti-PD-1/PD-L1 Checkpoint Inhibitors

Even though anti-PD-1/PD-L1 immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) have improved survival, a high percentage of patients still do not respond to ICIs. Myeloid-derived suppressor cells (MDSCs) are circulating cells that express PD-L1 and can infiltrate and proliferate in the tumor microenvironment, inducing immunosuppression. By evaluating changes in PD-L1 expression of live peripheral blood MDSCs, we are able to define a new PD-L1 index, useful in predicting ICI escape in NSCLC patients before initiating anti-PD-1/PD-L1 immunotherapy. In this study, a cohort of 37 NSCLC patients was prospectively analyzed, obtaining independent PD-L1 indexes. In patients with a PD-L1 index > 5.88, progressive disease occurred in 58.33% of patients [median progression-free survival (PFS) = 5.73 months; 95%CI = 2.67–20.53], showing significant differences when compared with patients with a PD-L1 index ≤ 5.88, in whom 7.69% progressed and median PFS was not reached (NR); p-value = 0.0042. Overall survival (OS) was significantly worse in patients with a high vs. low PD-L1 index (41.67% vs. 76.92%; median OS = 18.03 months, 95%CI = 6.77–25.23 vs. NR, 95%CI = 1.87-NR; p-value = 0.035). The PD-L1 index can be applied to stratify NSCLC patients according to their probability of response to ICIs at baseline. In addition to quantifying tumoral expression, this index could be used to compare nonresponse to treatment.

Effect of thymalfasin on myeloid-derived suppressor cells in patients with non-small cell lung cancer.

To observe the effect of thymalfasin on myeloid-derived suppressor cells (MDSCs) subsets in peripheral blood of patients with non-small cell lung cancer (NSCLC). 50 cases of NSCLC (NSCLC group) diagnosed in Chest Hospital of Jiangxi Province were selected as the research subjects, and 50 healthy subjects who underwent physical examination in our hospital during the same period were selected as the healthy control group. The expression of HLA-DR-CD14-CD33+ MDSCs in peripheral blood mononuclear cells and tumor tissue single cell suspension of NSCLC patients before and after thymalfasin treatment was explored by flow cytometry. The proportion of MDSCs in peripheral blood of NSCLC group was 1.70±0.52%, which was significantly higher than that in peripheral blood (0.51±0.15%) of healthy controls (P < 0.05). The proportion of HLA-DR-CD14-CD33+ MDSCs in the tissues of NSCLC group was 1.65±0.43% before treatment and 1.15±0.50% after treatment (P < 0.05). The proportion of MDSCs in peripheral blood of NSCLC patients before treatment was 1.70±0.52%, and that after treatment was 0.59±0.18% (P < 0.05). Thymalfasin can reduce the number of MDSCs in peripheral blood mononuclear cells. The application of thymalfasin in the treatment of NSCLC patients can help to enhance the anti-tumor effect.

A research on the influence of G-CSF mobilization on donor's peripheral blood MDSCs and its relationship with patient prognosis

ObjectiveTo discuss the effects of mobilization of healthy donors with granulocyte colony-stimulating factor (G-CSF) on the absolute values and functions of myeloid-derived suppressor cells (MDSCs) and subpopulations of M-MDSCs and P-MDSCs in their peripheral blood. In addition, this study also aims to investigate the impacts of the adoptively transferred MDSCs from the grafts to the patients on their prognosis and immune reconstitution. MethodsThe selection of 72 donors and 72 patients were conducted for allogeneic hematopoietic stem cell transplantation (allo-HSCT) from August 2022 to December 2022 at Lu Daopei Hospital in Beijing, China. Statistical calculations were performed by Wilcoxon signed-rank test, Kruskal Wallis test, χ2 test, Kaplan Meier test, and log-rank test to analyze the data. Results & ConclusionG-CSF induced significant amplification of MDSCs in the peripheral blood of donors in percentage and absolute values. Whether the level of P-MDSCs in patients conducted for the adoptive transfer of P - MDSCs is higher than 3.7× 107/kg or lower than 1.4× 107/kg leads to a poor prognosis of the patients. Ensuring a balanced state of MDSCs is crucial for effective immunotherapy. Transferring a high level of MDSCs from the graft to the patient's body is advantageous for the development of MDSCs while simultaneously inhibiting the proliferation of lymphocyte subgroups.

Preliminary study on the significance of pathological characteristics analysis of breast cancer and detection of peripheral blood myeloid-derived suppressor cells in the evaluation of biological characteristics

ABSTRACT To explore the significance of the analysis of pathological characteristics of breast cancer and the detection of myeloid-derived suppressor cell (MDSC) levels in peripheral blood for the evaluation of biological characteristics. 138 breast cancer patients were enrolled as the research group, while 138 patients with benign breast diseases were included as the control group. All patients underwent pathological analysis and detection of peripheral blood MDSCs levels, progesterone receptor (PR), estrogen receptor (ER), human epidermal growth factor receptor 2 (HER-2), and proliferating cell nuclear antigen (Ki-67). A factorial study of stage I, II, and III breast cancer patients showed significant differences in clinicopathological characteristics, including age, tumor size, lymph node metastases, histological grading, Neuropsychiatric Inventory (NPI) score, pathological type, and family history (P < 0.05). The research group had higher levels of peripheral blood MDSCs and different cell surface markers compared to the control group (P<0.05). Positive expression of biological molecules in breast cancer, such as PR, ER, HER-2, and Ki-67, had significant differences based on lymph node metastasis and tumor size (P < 0.05). The quality of survival scores was higher in stages I and II compared to stage III (P < 0.05). Age, recurrence, metastasis, and other pathological characteristics of breast cancer have a direct impact on clinical outcomes and survival rates. Peripheral blood levels of MDSCs and other cell surface markers are significantly elevated, serving as a crucial benchmark for the subsequent evaluation of breast cancer progression.

Increased circulating monocyte MDSCs positively correlate with serum Interleukin-10 in metastatic melanoma patients.

Numerous immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs) and inhibitory cytokines identified in melanoma microenvironment have the important role in immune escape. Therefore, in this study we analyzed monocytic (m)MDSCs in peripheral blood of metastatic melanoma (MM) patients. In peripheral blood of 35 MM patients and 30 healthy controls we analyzed percentage of CD14 + HLA-DR- mMDSCs in monocyte gate and the mean fluorescence intensity of Foxp3 in CD25 + CD4 + regulatory T cells by Flow cytometry. Serum levels of transforming growth factor beta, interferon-gamma, interleukin (IL)-6, IL-8, IL-10 are measured by ELISA assays. In this study MM patients have significantly higher percentage of CD14 + HLA-DR- mMDSCs, as well as increased the baseline mMDSC/PBMC subset (NK, T, B cells, monocytes) ratio. Although there is no significant difference in the percentage of mMDSCs between groups of MM patients with different localization of distant metastasis, patients with elevated serum lactate dehydrogenase (LDH) have statistically significant higher percentage of these cells compared to LDH negative patients. Furthermore, in MM patients there is statistically significant positive correlation between values of IL-10 and the percentage of mMDSCs, only. Therefore, therapeutics that target circulating mMDSCs and IL-10 may have a big importance in the improvement of antitumor immunity in MM patients.

Lnc-17Rik promotes the immunosuppressive function of Myeloid-Derived suppressive cells in esophageal cancer

Myeloid-derived suppressor cells (MDSCs) are a population of immature bone marrow cells that accumulate in large numbers in the spleen, peripheral blood, bone marrow, lymph nodes, and local and metastatic foci of tumors. C/EBP homologous protein (CHOP) and CCAAT/enhancer binding protein β (C/EBPβ) play key roles in regulating the immunosuppressive function and differentiation of MDSCs. Our study revealed that the long noncoding RNA Lnc-17Rik was able to promote immunosuppression in tumors by facilitating the activation and expression of key genes involved in MDSC differentiation. Lnc-17Rik was shown to directly interact with CHOP and C/EBPβ LIP to facilitate their dissociation from the transcriptional repressor complex involving C/EBP LAP/LIP/CHOP. Moreover, Lnc-17Rik increased the association of WD repeat-containing protein 5 (WDR5) with C/EBP LAP, promoting H3K4me3 enrichment in the promoter regions of arginase 1 (Arg-1), cyclooxygenase 2 (COX2), nitric oxide synthase 2 (NOS2) and NADPH oxidase 2 (NOX2) to enhance the expression of these genes. Furthermore, using a CD45 chimeric model we confirmed that Lnc-17Rik promoted the differentiation of monocytic (M)-MDSCs in vivo with the introduction of Lnc-17Rik-overexpressing MDSCs shown to promote tumor growth as a result of enhancing their immunosuppressive function. Notably, human Lnc-17Rik is highly homologous to mouse Lnc-17Rik and fulfills similar functions in human MDSC-like cells. In addition, we also found a high level of Lnc-17Rik in peripheral blood MDSC of patients with esophageal cancer. These findings suggest that Lnc-17Rik plays an important role in controlling the immunosuppressive function of MDSCs in the tumor environment and may further serve as a potential therapeutic target for patients with esophageal cancer.

A pilot phase Ib study to evaluate tadalafil to overcome immunosuppression during chemoradiotherapy for IDH-wild-type glioblastoma.

Myeloid-derived suppressor cells (MDSCs) are critical regulators of immunosuppression and radioresistance in glioblastoma (GBM). The primary objective of this pilot phase Ib study was to validate the on-target effect of tadalafil on inhibiting MDSCs in peripheral blood and its safety when combined with chemoradiotherapy in GBM patients. Patients with newly diagnosed IDH-wild-type GBM received radiation therapy (RT) and temozolomide (TMZ) combined with oral tadalafil for 2 months. A historical cohort of 12 GBM patients treated with RT and TMZ was used as the comparison group. The ratio of MDSCs, T cells, and cytokines at week 6 of RT compared to baseline were analyzed using flow cytometry. Progression-free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method. Tadalafil was well tolerated with no dose-limiting toxicity among 16 evaluable patients. The tadalafil cohort had a significantly lower ratio of circulating MDSCs than the control: granulocytic-MDSCs (mean 0.78 versus 3.21, respectively, P = 0.01) and monocytic-MDSCs (1.02 versus 1.96, respectively, P = 0.006). Tadalafil increased the CD8 ratio compared to the control (1.99 versus 0.70, respectively, P < 0.001), especially the PD-1-CD8 T cells expressing Ki-67, CD38, HLA-DR, CD28, and granzyme B. Proinflammatory cytokine IL-1β was also significantly increased after tadalafil compared to the control. The tadalafil cohort did not have significantly different PFS and OS than the historical control. Concurrent tadalafil is well tolerated during chemoradiotherapy for GBM. Tadalafil is associated with a reduction of peripheral MDSCs after chemoradiotherapy and increased CD8 T-cell proliferation and activation.

Effect of MMR Vaccination to Mitigate Severe Sequelae Associated With COVID-19: Challenges and Lessons Learned.

Mortality in COVID-19 cases was strongly associated with progressive lung inflammation and eventual sepsis. There is mounting evidence that live attenuated vaccines commonly administered during childhood, also provide beneficial non-specific immune effects, including reduced mortality and hospitalization due to unrelated infections. It has been proposed that live attenuated vaccine-associated non-specific effects are a result of inducing trained innate immunity to function more effectively against broader infections. In support of this, our laboratory has reported that immunization with a live attenuated fungal strain induces a novel form of trained innate immunity which provides protection against various inducers of sepsis in mice via myeloid-derived suppressor cells. Accordingly, we initiated a randomized control clinical trial with the live attenuated Measles, Mumps, Rubella (MMR) vaccine in healthcare workers in the greater New Orleans area aimed at preventing/reducing severe lung inflammation/sepsis associated with COVID-19 (ClinicalTrials.gov Identifier: NCT04475081). Included was an outcome to evaluate the myeloid-derived suppressor cell populations in blood between those administered the MMR vaccine vs placebo. The unanticipated emergency approval of several COVID-19 vaccines in the midst of the MMR clinical trials eliminated the ability to examine effects of the MMR vaccine on COVID-19-related health status. Unfortunately, we were also unable to show any impact of the MMR vaccine on peripheral blood myeloid-derived suppressor cells due to several inherent limitations (low percentages of blood leukocytes, small sample size), that also included a collaboration with a similar trial (CROWN CORONATION; ClinicalTrials.gov Identifier: NCT04333732) in St. Louis, MO. In contrast, monitoring the COVID-19 vaccine response in trial participants revealed that high COVID-19 antibody titers occurred more often in those who received the MMR vaccine vs placebo. While the trial was largely inconclusive, lessons learned from addressing several trial-associated challenges may aid future studies that test the non-specific beneficial immune effects of live attenuated vaccines.

Anlotinib reduces the suppressive capacity of monocytic myeloid-derived suppressor cells and potentiates the immune microenvironment normalization window in a mouse lung cancer model.

By exploring the effects of an antiangiogenic small molecule drug named anlotinib on the levels of myeloid-derived suppressor cells (MDSCs) in a mouse xenograft model of lung cancer, the role of anti-angiogenesis in remodeling the immune microenvironment was discussed. In addition, the impact of anlotinib on the normalization of the immune microenvironment and time window was examined, providing a theoretical basis for the optimization of clinical strategies applying anlotinib combined with PD-1 inhibitors. On the basis of the LLC mouse xenograft model, MDSCs and MDSCs + immune microenvironment were examined in tissues, respectively, according to different samples. The former observation included the control (group A) and anlotinib monotherapy (group B) groups; the latter also included the control (group C) and anlotinib monotherapy (group D) groups. The levels of MDSCs in peripheral blood at different time points were analyzed by flow cytometry, and the levels of MDSCs in tissue samples at different time points were evaluated by immunofluorescence and immunohistochemistry. The volumes of subcutaneous xenografts were significantly smaller in the anlotinib treatment group compared with the control group ( P < 0.005). Flow cytometry showed that compared with the control group, the intratumoral percentages of total MDSCs ( P < 0.01) and mononuclear-MDSCs ( P < 0.05) were significantly decreased on days 3 and 17 after anlotinib treatment in peripheral blood samples; however, there was no significant difference in granulocytic-MDSCs changes between the experimental and control groups. Immunofluorescence showed that the levels of MDSCs in both the experimental and control groups reached the lowest points 10 days after drug administration, and were significantly lower in the experimental group than in the control group ( P < 0.05). Anlotinib reduces the levels of MDSCs in the mouse xenograft model of lung cancer, with the characteristics of time window. This study provides a basis for further exploring strategies for anti-angiogenic treatment combined with immunotherapy in lung cancer based on time-window dosing.

P-421 Increased myeloid-derived suppressor cells in women with recurrent miscarriage and recurrent implantation failure

Abstract Study question We sought to explore the levels of myeloid-derived suppressor cells (MDSCs) in women experiencing recurrent miscarriage (RM) or recurrent implantation failure (RIF) Summary answer MDSCs were significantly expanded in RM patients with respect to fertile healthy women (p = 0.03, 8.25 vs 7.00). What is known already RM and RIF are two distinct disorders that can be associated with a baseline pro-inflammatory state. Different surrogate inflammatory biomarkers have been associated with these disorders in a subgroup of patients, including expanded cytotoxic NK cells, increased pro-inflammatory cytokines or reduced regulatory T cells (TReg). MDSCs are a heterogeneous population of leukocytes, known for their capacity to modulate immune responses. The immunosuppressive function of MDSC in cancer has been well established, while a controversial role in autoimmune diseases has been reported. Typically, there are two major groups of MDSCs in humans: granulocytic/polymorphonuclear MDSCs (PMN-MDSCs) and monocytic MDSCs (M-MDSCs). Study design, size, duration A cross-sectional study to evaluate the levels of MDSCs in women with RM and RIF consecutively referred to our Reproductive Immunology Unit. 55 patients and 23 healthy women were evaluated from 2021 to 2022. RM was defined as the loss of two or more pregnancies and not necessarily consecutive. RIF was defined as the failure to achieve a clinical pregnancy after transferring at least four good-quality embryos. Participants/materials, setting, methods A full fertility screening was performed for all women and their partners as part of routine care. A group of healthy non-pregnant women up to 45 years old with two or more children (proven fertility) and no spontaneous miscarriage was used as control group. Freshly collected blood samples were analyzed by multiparametric flow cytometry using a BD FACS CANTO II. Peripheral blood M-MDSCs were characterized based on HLA-DR, CD14, CD33 and CD45 expression. Main results and the role of chance In this study, we evaluated 55 women, 35 that fulfilled RM criteria and 20 with RIF. In addition, a group of 23 non-pregnant fertile women was included as a control group. We characterized MDSCs as CD14+CD33+CD45+HLA-DR-/LOW, according to previous reports. We observed a significant expansion of peripheral blood MDSCs in RM group compared to the control group (8.25% [6.62-11.9] vs 7.05% [6-7.8], p = 0.03) and RIF group showed a similar increasing trend compared to controls (8.6% [5.65-12.35] vs 7.05% [6-7.8], p = 0.09). We performed ROC curves analysis to evaluate the predictive power. We established an optimal cut-off level of 8.3% in RM group, with a sensitivity of 50% and a specificity of 86.96%. Moreover, women with more than 8.3% had a higher probability of presenting RM compared to the control group (OR: 6.66; CI: 1.68-26.46). MDSCs are characterized by their ability to exert a potent immunosuppressive function. However, recent investigations have shown that MDSCs could act as pro-inflammatory cells under certain inflammatory conditions, such as autoimmune diseases. In this context, MDSCs could worsen the pro-inflammatory state in women, leading to miscarriage or implantation failure. Limitations, reasons for caution In order to validate these results, we should extend our cohort and control group. Moreover, we need to perform a functional evaluation of this subset so we could elucidate their role in these conditions. Wider implications of the findings MDSCs might be a good predictor for RM and RIF patients and with others (as expanded NK cells) may classify a subgroup of patients with a pro-inflammatory profile that can benefit from personalized therapies. Trial registration number Not aplicable

Targeted Gene Expression Profiling of Human Myeloid Cells From Blood and Lung Compartments of Patients With Tuberculosis and Other Lung Diseases.

Myeloid-derived suppressor cells (MDSC) have been identified in the peripheral blood and granulomas of patients with active TB disease, but their phenotype-, function-, and immunosuppressive mechanism- spectrum remains unclear. Importantly, the frequency and signaling pathways of MDSC at the site of disease is unknown with no indication how this compares to MDSC identified in peripheral blood or to those of related myeloid counterparts such as alveolar macrophages and monocytes. Most phenotypic and functional markers have been described in oncological studies but have not yet been validated in TB. Using a panel of 43 genes selected from pathways previously shown to contribute to tumor-derived MDSC, we set out to evaluate if the expression of these additional functional markers and properties may also be relevant to TB-derived MDSC. Differential expression was investigated between MDSC, alveolar macrophages and monocytes enriched from bronchoalveolar lavage fluid and peripheral blood of patients with active TB, patients with other lung diseases (OLD). Results demonstrated that anatomical compartments may drive compartment-specific immunological responses and subsequent MDSC immunosuppressive functions, demonstrated by the observation that MDSC and/or monocytes from PB alone can discriminate, via hierarchical clustering, between patients with active TB disease and OLD. Our data show that the gene expression patterns of MDSC in peripheral blood and bronchoalveolar lavage fluid do not cluster according to disease states (TB vs OLD). This suggests that MDSC from TB patients may display similar gene expression profiles to those found for MDSC in cancer, but this needs to be validated in a larger cohort. These are important observations for TB research and may provide direction for future studies aimed at repurposing and validating cancer immunotherapies for use in TB.

Granulocytic and Monocytic Myeloid-Derived Suppressor Cells are Functionally and Prognostically Different in Patients with Chronic Myeloid Leukemia.

Myeloid-derived suppressor cells (MDSCs) represent phenotypically heterogeneous populations that suppress tumor-specific T-cell responses. MDSCs are produced from myeloid precursors in emergent states and are increased in several hematologic malignancies. We evaluated the differences in the levels and prognostic significance of MDSCs according to the clinical status of chronic myeloid leukemia (CML). The percentages and numbers of granulocytic (g)MDSCs and monocytic (m)MDSCs in peripheral blood (PB) and bone marrow (BM) aspirates were determined by five-color flow cytometry (HLA-DR/CD11b/CD15/CD33/CD14). The median BM-gMDSC% and PB-gMDSC% of the CML group were lower than those of the complete hematologic response (CHR) and control groups (P<0.001). In the CHR group, patients with major molecular response (MMR) showed higher median BM-gMDSC% than those without MMR (P=0.039). Conversely, the PB-mMDSC number of the CML group was higher than those of the CHR and control groups (P<0.001). Patients with high PB-gMDSC number exhibited superior survival to those with low PB-gMDSC number (P=0.021), and patients with high PB-mMDSC% showed inferior survival to those with low PB-mMDSC%, but there was no statistical significance (P=0.182). Increased gMDSCs at CHR may reflect non-leukemic granulopoiesis, and a high number of PB-gMDSCs suggests better prognosis in CML. However, mMDSCs may be associated with malignant conditions and poor prognosis.

Chronic Hepatitis C Virus Infection Modulates the Transcriptional Profiles of CD4+ T Cells.

Background Chronic hepatitis C (CHC) is associated with altered cell-mediated immune response. Objective The aim of the study was to characterize functional alterations in CD4+ T cell subsets and myeloid-derived suppressor cells (MDSCs) during chronic hepatitis C virus (HCV) infection. Methodology. The expression levels of the lineage-defining transcriptional factors (TFs) T-bet, Gata3, Rorγt, and Foxp3 in circulating CD4+ T cells and percentages of MDSCs in peripheral blood were evaluated in 33 patients with CHC, 31 persons, who had spontaneously cleared the HCV infection, and 30 healthy subjects. Analysis. The CD4+ T cells TFs T-bet (T-box expressed in T cells), Foxp3 (Forkhead box P3 transcription factor), Gata3 (Gata-binding protein 3), and Rorγt (retinoic-acid-related orphan receptor gamma) and activation of CD8+ T cells, as well as percentages of MDSCs, were measured by multicolor flow cytometry after intracellular and surface staining of peripheral blood mononuclear cells with fluorescent monoclonal antibodies. Result The patients with CHC had significantly lower percentages of CD4+ T cells expressing Rorγt and Gata3 and higher percentages of Foxp3-expressing CD4+ T cells than healthy controls and persons who spontaneously cleared HCV infection. The ratios of T-bet+/Gata3+ and Foxp3+/Rorγt+ CD4+ T cells were the highest in the patients with CHC. In the patients with CHC, the percentages of Gata3+ and Rorγt+ CD4+ T cells and the percentages of T-bet+ CD4+ T cells and CD38+/HLA-DR+ CD8+ T cells demonstrated significant positive correlations. In addition, the percentage of CD38+/HLA-DR+ CD8+ T cells correlated negatively with the percentage of MDSCs. Conclusion Chronic HCV infection is associated with downregulation of TFs Gata3 and Rorγt polarizing CD4+ T cells into Th2 and Th17 phenotypes together with upregulation of Foxp3 responsible for induction of regulatory T cells suppressing immune response.

Myeloid-derived suppressor cells level and MUC1 expression in de novo acute myeloid leukemia

AbstractBackgroundAcute myeloid leukemia (AML) is the most common acute leukemia occurring in adults. It is an aggressive myeloid neoplasm with maturation arrest of myelopoiesis, leading to an accumulation of myeloblasts in the bone marrow and peripheral blood.ObjectiveTo evaluate alterations in myeloid-derived suppressor cells level and MUC1 gene expression in patients with de novo acute myeloid leukemia concerning disease characteristics and response to induction chemotherapy.Patients and methodsThe study was performed on 50 AML patients and 50 healthy controls. Detection of myeloid-derived suppressor cells (MDSCs) in peripheral blood was performed by mononuclear separation and flow cytometry. MUC1 gene expression was performed by RNA extraction, reverse transcription, and real-time PCR at Hematology Department Medical Research Institute, Alexandria University.ResultsWe have demonstrated that AML patients had both increased presence of MDSCs in peripheral blood as well as MUC1 overexpression in comparison to normal controls. MDSCs showed a significant correlation regarding response to induction chemotherapy on day 28. While MDSCs and not MUC1 are associated with inferior response to induction chemotherapy on day 28.ConclusionThe current data suggested that AML patients exhibit an increased presence of MDSCs as well as MUC1 gene overexpression in comparison with normal controls. While MDSCs showed a significant correlation regarding response to induction chemotherapy on day 28, MDSCs and not MUC1 are associated with inferior response to induction chemotherapy on the same day.

Myeloid-derived suppressor cells in gastroenteropancreatic neuroendocrine neoplasms.

Expanded myeloid-derived suppressor cells (MDSCs) correlate with disseminated metastases and poor prognosis in various human cancers. However, the role of MDSCs in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) is still unknown. We investigated the distribution of MDSCs and their clinical significance in patients with GEP-NENs. Peripheral blood mononuclear cells (PBMCs) and paraffin-embedded tumor tissues were acquired from patients with GEP-NENs. Multicolor flow cytometry was performed to determine the frequency of MDSCs in peripheral blood, and immunohistochemistry was performed to determine the distribution of MDSCs in primary NEN tissues. Compared to healthy donors, patients with GEP-NENs had significantly higher levels of circulating monocytic (M)-MDSCs. Frequency of M-MDSCs in both peripheral blood and primary NEN tissues was significantly higher in GEP-NEN patients with metastases compared to patients without metastases. Tumor-infiltrating M-MDSCs can serve as a valuable prognostic marker of metastasis in patients with GEP-NENs, as indicated by the area under the curve (AUC) = 0.71; 95% confidence interval (CI) = 0.56-0.87, p < 0.01. High M-MDSC levels were associated with significantly increased metastases in patients with GEP-NENs. M-MDSCs appear to be a promising prognostic immunologic biomarker and therapeutic target in GEP-NEN management.

Palliative Radiofrequency Ablation Accelerates the Residual Tumor Progression Through Increasing Tumor-Infiltrating MDSCs and Reducing T-Cell-Mediated Anti-Tumor Immune Responses in Animal Model.

Previous studies showed that radiofrequency ablation (RFA) has a favorable treatment efficacy for hepatocellular carcinoma (HCC) or colorectal liver metastases (CRLMs). Palliative RFA (pRFA) resulting from larger HCC or multiple CRLMs further accelerated the progression of potential residual tumor, yet its mechanism was still unknown. This study investigated the influence of myeloid-derived suppressor cells (MDSCs) on T-cell immune responses and tumor recurrence after pRFA. CT26 tumor models were used. The percentage of MDSCs in peripheral blood was analyzed by flow cytometry after pRFA. The level of Th1 and Th2 cytokines were measured by ELISA through different treatments (n = 4/group). The tumor-infiltrating MDSCs, dendritic cells, and intracellular cytokines level were analyzed by IHC staining after different treatments. The functional CD8+ T cells were confirmed by the co-localization immunofluorescence staining. The long-term outcomes were also evaluated through CT26 and 4T1 tumor models. The results showed that tumor models treated with pRFA displayed significant increases in the percentage of MDSCs of peripheral blood and tumor infiltration. The expression level of TGF-β and IL-6 after pRFA was higher than that before pRFA by ELISA and IHC staining. After depleting MDSCs by combining with Abs, the pRFA + Abs group achieved a higher level of Th1 cytokines and greatly enhanced the percentage of tumor-infiltrating functional CD8+ T cells when compared with pRFA alone. The depletion of MDSCs through combination with Abs also resulted in tumor regression. In conclusion, pRFA accelerates the residual tumor progression through increasing tumor-infiltrating MDSCs and reducing T-cell-mediated anti-tumor immune responses, which could provide a potential approach for delaying tumor recurrence caused by pRFA.

THE FEATURE OF MDSCS IN THE LONG-TERM STABLE KIDNEY TRANSPLANT RECIPIENTS AFTER DIFFERENT IMMUNOSUPPRESSION THERAPY

Objective: Myeloid-derived suppressor cells (MDSCs) play an important role in immune tolerance. The aim of this study is to investigate different feature of MDSCs in the long-term survival with kidney transplant recipients. Methods: From January 1989 to November 2008, a total number of 35 Recipients operated in kidney transplantation department of the first affiliated hospital of Xi’an Jiaotong university, were selected. They all had stable kidney function now. Recipients were divided into 4 Four three groups: Aza +Pred (n=5; Tacrolimus inhibitors group (FK506 + MMF + Pred) (n=10; Cyclosporine inhibitors group (CsA + MMF + Pred) (n=10); rapamycin group (RAPA + MMF + Pred) (n=10). The expression of MDSCs in peripheral blood was determined by flow cytometry. The expression of serum HLA-G5 and sCD30 was detected by ELLISA. MDSCs of mice were also induced in vitro, which were also treated with different immunosuppression as above. Results: The percentage of MDSCs was significantly higher in calcineurin inhibitors group than rapamycin inhibitors group. The level of MDSCs between Cyclosporine group and tacrolimus group was no significant difference. Rapamycin significantly reduces the immunosuppressive function of MDSCs on T cells compared with CNI group and reduces the number of MDSCs induced in vitro. No significant difference was observed between Cyclosporine group and tacrolimus group. Conclusions: 1. Rapamycin inhibits the differentiation and function of MDSCs in vitro and in vivo, which maybe bad for immune tolerance. When select rapamycin as immunosuppression, should be careful in Long-term survival with kidney transplant recipients. 2. MDSCs, HLA-G5, CD30 may act an effective method to evaluate immune status of kidney recipients.

Umbilical cord blood-derived mesenchymal stromal cells promote myeloid-derived suppressor cell proliferation by secreting HLA-G to reduce acute graft-versus-host disease after hematopoietic stem cell transplantation

Background aimsMesenchymal stem cells (MSCs) use multiple mechanisms to constrain both innate and adaptive immune responses to prevent graft-versus-host disease (GVHD). Myeloid-derived suppressor cells (MDSCs), as a heterogeneous population of early myeloid progenitor cells originating from bone marrow, are a naturally occurring immune regulatory population associated with inhibition of ongoing inflammatory responses, indicating their potential for GVHD therapy. There is accumulating evidence that MSCs and MDSCs do not act independently, but rather establish crosstalk. However, the role of MSCs in MDSC expansion and activation in GVHD remains unexplored. MethodsIn vitro experiments included 2 groups: peripheral blood mononuclear cells (PBMCs) after mobilization and human umbilical cord blood-derived MSCs (UCB-MSCs) co-cultured with PBMCs. The number and functional difference of MDSCs in PBMCs were determined by flow cytometry. The culture supernatants of co-cultured cells were analyzed to identify cytokines involved in MDSC proliferation. The relationship between MSCs and MDSCs was clarified in GVHD and graft-versus-leukemia (GVL) animal models. ResultsIn vitro experiments confirmed that UCB-MSCs secreted HLA-G protein to promote and maintain the proliferation of MDSCs in peripheral blood after granulocyte colony-stimulating factor mobilization, and UCB-MSCs mediated the function of MDSCs to inhibit the proliferation of T cells and promote the proliferation of regulatory T cells. UCB-MSCs overexpressing HLA-G induced MDSC production in recipient mice, improved the ability of MDSCs to suppress T cells and further reduced acute GVHD (aGVHD) symptoms and survival time without influencing GVL effects. ConclusionsUCB-MSCs expanded MDSCs via HLA-G/Ig-like transcript 4, reducing the severity of aGVHD without affecting GVL. The immunosuppressive potential of MSCs for the treatment of aGVHD significantly affects the development of MDSCs, thereby consolidating the position of MSCs in the prevention and treatment of aGVHD.

Hypofractionated Irradiation Suppressed the Off-Target Mouse Hepatocarcinoma Growth by Inhibiting Myeloid-Derived Suppressor Cell-Mediated Immune Suppression.

Background: Stereotactic radiotherapy treats hepatocellular carcinoma (HCC) at different stages effectively and safely. Besides its direct killing of cancer cells, radiotherapy stimulates host immunity against hepatoma. However, the role of myeloid-derived suppressor cells (MDSCs) in on-target and off-target anti-HCC effects induced by hypofractionated irradiation (IR) is unclear.Methods and Materials: Hepa1-6 and H22 allogeneic transplanted tumors on hind limbs of C57BL/6 and Institute of Cancer Research (ICR) mice, respectively, were irradiated with 0, 2.5, 4, 6, or 8 Gy/fraction until the total dose reached 40 Gy. The off-target effect induced by the IR was investigated by subsequently inoculating the same HCC cells subcutaneously on the abdomen. MDSCs in peripheral blood and tumor tissues were measured by flow cytometry or immunofluorescence microscopy analysis. IL-6, regulated on activation normal T cell expressed and secreted (RANTES), and granulocyte colony-stimulating factor (G-CSF) in irradiated mouse plasma and hepatoma cell cultures were measured with ELISA kits. Conditioned media (CM) from irradiated HCC cell cultures on bone marrow cell differentiation and MDSC proliferation were examined by co-culture and flow cytometry.Results: Our study showed that the IR of primarily inoculated HCC on hind limbs created an “in situ tumor vaccine” and triggered the antitumor immunity. The immunity was capable of suppressing the growth of the same type of HCC subcutaneously implanted on the abdomen, accompanied with reduced MDSCs in both blood and tumors. The decreased MDSCs were associated with low plasma levels of IL-6, RANTES, and G-CSF. The cytokines IL-6 and RANTES in the CM were lower in the high single IR dose group than in the control groups, but G-CSF was higher. The CM from high single-dose IR-Hepa1-6 cell culture reduced the differentiation of C57BL/6 mouse bone marrow cells into MDSCs, whereas CM from high single-dose IR-H22 cells reduced the proliferation of MDSCs, which might be due to the decreased p-STAT3 in bone marrow cells.Conclusions: The hypofractionated IR on transplanted tumors at the primary location exerted a strong antitumor effect on the same tumor at a different location (off target). This abscopal effect is most likely through the reduction of MDSCs and decrease of IL-6, RANTES, and G-CSF.

Role and mechanism of splenic myeloid-derived suppressor cells in sepsis-induced adrenal injury in mice

To investigate the role and mechanism of splenic myeloid-derived suppressor cells (MDSCs) in sepsis-induced adrenal injury (SAI). Thirty male C57 mice aged 6-8 weeks were randomly divided into normal control group (n = 5), sham operation group (Sham group, n = 5), sepsis model group [cecal ligation and perforation (CLP) group, n = 10] and sepsis+splenectomy group (CLPS group, n = 10). The sepsis model of mice was reproduced by CLP method. In Sham group, only the cecum was opened and separated, then closed, without CLP. In CLPS group, the spleen was removed before CLP. In normal control group, no challenge was given. After 24 hours, the rats were sacrificed by anesthesia, and peripheral blood, spleen, bone marrow, and bilateral adrenal glands were harvested. The pathological of adrenal gland was assessed by hematoxylin-eosin (HE) staining under optical microscope. The ratio of MDSCs in peripheral blood, spleen and bone marrow was determined by flow cytometry. The expressions of MDSCs surface antigen CD11b, Gr-1 and interleukins (IL-6, IL-1β) mRNA in adrenal tissue were measured by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Western Blot was used to detect the expressions of mammalian rapamycin target protein (mTOR) pathway related proteins including total mTOR (T-mTOR), phosphorylation of mTOR (p-mTOR) and caspase-3. The adrenal cortex and medulla of the normal control group and Sham group were intact and the structure was clear under optical microscope, while in the CLP group, the adrenal gland showed edema, cortical hemorrhage and cell edema. Compared with the CLP group, the adrenal tissue injury was significantly reduced in the CLPS group. Compared with the normal control group and Sham group, MDSCs ratio in the peripheral blood was significantly increased and significantly reduced in the spleen in the CLP group, but there was no significant difference in bone marrow, the expression levels of CD11b, Gr-1, IL-6, IL-1β mRNA and caspase-3 protein were increased significantly and p-mTOR protein expression was significantly decreased in adrenal tissue, there was no significant difference in the expression of T-mTOR protein. Compared with the CLP group, in the CLPS group, the MDSCs ratio in the peripheral blood was significantly decreased (0.143±0.011 vs. 0.324±0.023, P < 0.01), the expression levels of CD11b, Gr-1, IL-6 , IL-1β mRNA and caspase-3 protein in adrenal gland were significantly decreased [CD11b mRNA (2-ΔΔCt): 2.90±0.56 vs. 5.74±0.13, Gr-1 mRNA (2-ΔΔCt): 2.71±0.14 vs. 4.59±0.46, IL-6 mRNA (2-ΔΔCt): 2.44±0.64 vs. 5.17±1.04, IL-1β mRNA (2-ΔΔCt): 3.58±0.52 vs. 4.44±0.26, caspase-3 protein (caspase-3/GAPDH): 0.05±0.01 vs. 0.13±0.02, all P < 0.01], the p-mTOR protein expression was significantly increased (p-mTOR/GAPDH: 0.61±0.11 vs. 0.27±0.04, P < 0.01). The spleen is the major source of MDSCs in SAI. Splenectomy can attenuate SAI by reducing mobilization of MDSCs and activating the mTOR signaling pathway.