Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients. EL4 tumors were established in C57BL/6 mice, then mice were injected either with PBS (n=3) or 12.5mg/kg Con A (n=3). Three hours later mice were sacrificed, liver CD11b+Gr-1+ cells were sorted and samples were processed for gene expression analysis.
Project description:Myeloid-derived suppressor cells (MDSC) represent a heterogeneous population of immature myeloid cells that accumulate in blood, liver, spleen and tumors upon chronic inflammation and tumor development in patients and mice. Acute hepatitis is characterized by a fast infiltration of inflammatory cells in the liver and increased enzymatic activity at this organ that could lead into liver fibrosis and cirrhosis. We have studied the biology of hepatic MDSC in acute hepatitis. Unexpectedly, hepatic MDSC, which accumulate in the liver of mice bearing subcutaneous tumors, failed to suppress inflammatory responses upon Con A injection, but instead were responsible for exacerbating acute liver damage. Phenotypic, genetic and functional studies demonstrated rapid changes of hepatic MDSC from a suppressor phenotype into a pro-inflammatory subset as early as 3 hours after Con A injection. An increase in the expression of pro-inflammatory cytokines, costimulatory molecules such as CD80, CD86 and CD40 along with a loss of suppressor function was noticed in mice upon Con A treatment. These changes were CD40-dependent and not found in CD40-/- MDSC. Interestingly, CD40 ligation of human MDSC in vitro resulted in down-regulation of arginase I expression and suppressor function. Finally, blockade of ROS production in hepatic MDSC ameliorated hepatocyte damage suggesting that MDSC mediated toxicity was ROS dependent. We believe that these findings reflect how MDSC plasticity can be modulated to promote inflammation, opening a new path for therapies targeting innate suppressive cells in cancer patients.
Project description:Myeloid-derived suppressor cells (MDSCs) have the capacity to suppress T cell-mediated immune responses, and impact clinical outcome of cancer, infections and transplantation settings. Although MDSCs were initially described as bone-marrow-derived immature myeloid cells (either monocytic [m-MDSC] or granulocytic [g-MDSC]), also mature neutrophils have been shown to exert MDSC activity towards T cells, in ways that so far remained unclear. In this study, we demonstrate that human neutrophils – both from healthy donors and cancer patients – do not exert MDSC activity unless they are activated. Using neutrophils with genetically well-defined defects, we found that reactive oxygen species (ROS) and granule-derived constituents are required for MDSC activity after direct CD11b-dependent neutrophil-T cell interactions. Besides these cellular interactions, neutrophils were engaged in the uptake of pieces of T cell membrane, a process called trogocytosis. Together, these interactions led to changes in T cell morphology, mitochondrial dysfunction and ATP depletion, as indicated by electron microscopy, mass spectrometry and metabolic parameters. Our studies characterize the different steps by which activated mature neutrophils induce functional T cell non-responsiveness and irreparable cell damage.
Project description:Myeloid derived Suppressor cells (MDSC) are heterogenous popluation of cells consists of two major subsets namely the monocytic Gr-1dull/int. and granulocytic (Gr-1high). These distinct two subsets use different mechanism to inhibit T cell response. In addition, how the function of these subsets is regulated is not known yet. The Gr-1dull/int. MDSC are suppressing T cells through IFNg dependent nitric oxide dependent manner. However, the exact suppressive mechanism of Gr-1high MDSC is not clear. Here we studied the role of a cytokine IFNg on the suppressive function of Gr-1high MDSC by comparing the gene expression of Gr-1high cells cultured alone versus those cultured with T cells which donot produce IFNgamma. CD11b+Gr-1high cells were purified from the splenocyte of CT-26 colon tumor bearing mice. The purified CD11b+Gr-1high MDSCs were cultured with IFNg-/- antigen specific T cells and re- sorted after 48h and RNA was extracted and gene expression was analyzed using topic-defined PIQORTM Immunology Microarrays.
Project description:Cancer-associated fibroblasts (CAF) promote immune suppression in the tumor microenvironment by polarizing monocytes to myeloid-derived suppressor cells (MDSC) that potently suppress T-cell function. Using a patient-derived coculture system, we profiled the cell surface proteome of CAF-induced MDSC to identify potential mechanism through which T-cell function is impaired.
Project description:Myeloid derived Suppressor cells (MDSC) are heterogenous popluation of cells consists of two major subsets namely the monocytic Gr-1dull/int. and granulocytic (Gr-1high). These distinct two subsets use different mechanism to inhibit T cell response. In addition, how the function of these subsets is regulated is not known yet. The Gr-1dull/int. MDSC are suppressing T cells through IFNg dependent nitric oxide dependent manner. However, the exact suppressive mechanism of Gr-1high MDSC is not clear. Here we studied the role of a cytokine IFNg on the suppressive function of Gr-1high MDSC by comparing the gene expression of Gr-1high cells cultured alone versus those cultured with T cells which donot produce IFNgamma.
Project description:Cancer-associated fibroblast (CAF) promote immune suppression in the tumor microenvironment by polarizing monocytes to myeloid-derived suppressor cells (MDSC) that potently suppress T-cell function. Using a patient-derived coculture system, we found that extracellular vesicles (EV) released by CAF-induced MDSC directly suppress T-cell proliferation. In this study, we profiled the protein cargo of the EVs isolated from CAF-MDSC and compared to related cell types.
Project description:The aim of the study is to evaluate whether the preoperative level of myeloid-derived suppressor cells is associated with postoperative complications classified by Clavien-Dindo categories. Levels of all MDSC, polymorphonuclear MDSC (PMNMDSC), monocytic MDSC (MMDSC), early-stage MDSC (EMDSC) and monocytic to polymorphonuclear MDSC ratio (M/PMN MDCS) were established and compared in patients with postoperative complications, severe postoperative complications (>= IIIA according to Clavien-Dindo) and severe septic complications.
Project description:Multiple Myeloma (MM) is a plasma cell malignancy with a well- documented immune dysfunction. We previously showed that granulocyte-myeloid derived suppressor cells (G-MDSC) are increased in MM thus to contribute to refractoriness to lenalidomide. MM-, differently from MGUS, mesenchymal cells lead myeloid precursors to acquire G-MDSC phenotype, suggesting that MM-microenvironment can affect myeloid maturation. Because there is a phenotypic overlapping between G-MDSC and mature high-density neutrophils (HDN), we investigated functionally HDN to gauge their contribution in immune-suppression in patients affected by monoclonal gammopathy of uncertain significance (MGUS) and symptomatic MM.
Project description:MDSC (myeloid-derived suppressor cells) can be divided into two subsets: granulocytic MDSC (G-MDSC) and monocyte MDSC (M-MDSC).We found that CHBP induced M-MDSC have stronger immunosuppressive function. To identify the specific role of CHBP induced M-MDSC, we used RNA squencing to compare the M-MDSC with CHBP induced M-MDSC. We analyzed the differential expressed genes between these two groups.