Project description:Myeloid derived suppressor cells (MDSC) playing the immune suppressive roles in tumor bearing host consists of two major subsets of granulocytic and monocytic cells. Granulocytic MDSC (G-MDSC) express CD11b+ Gr-1high Ly6G+ Ly6Clow and produce high level of reactive oxygen species (ROS). Interestingly, neutrophils are well known ROS producing cells during immune defensive process and share same surface markers with G-MDSC. These similar features always brought the fundamental questions what’s the difference between G-MDSC and neutrophils but it’s not yet proven clearly. In this study, we examined the gene expression of G-MDSC and neutrophils using Affymetrix microarray G-MDSC (CD11b+Ly6G+Ly6Clow) were purifed from splenocytes in EL4 lymphoma tumor bearing mice by positive selection of Ly6G using microbeads isolation. Neutrophils were purified from ascitic fluids induced after injection of milk protein, casein by negative selection of F4/80 and positive selection of Ly6G using microbeads isolation. Their RNA was extracted and gene expression was analyzed using Affymetrix microarray.
Project description:Myeloid-derived suppressor cells (MDSC) are a major barrier to anticancer responses. Although much is known about how MDSC promote tumor progression, little is known about how they develop. We hypothesized that MDSC develop as a consequence of tumor-induced downregulation of interferon regulatory factor-8 (IRF-8), a key myeloid developmental transcription factor. We showed that: 1) IRF8-deficiency in mice generated myeloid populations highly homologous to tumor-induced MDSC; 2) IRF-8 overexpression in mice reduced MDSC accumulation and retarded tumor growth; 3) MDSC-inducing factors, G-CSF or GM-CSF, facilitated IRF-8 downregulation via STAT3- or STAT5-dependent pathways, respectively; and 4) IRF-8 levels in MDSC-like subsets of breast cancer patients were depressed compared to healthy donors. Altogether, our data implicate IRF-8 as a novel MDSC-dependent transcription factor. Splenic CD11b+Gr-1high cell populations from tumor-bearing mice, IRF8 knockout mice or non-tumor-bearing control mice were purified in two independent experiments by flow cytometry (> 97% purity) and subjected to whole genome expression profiling using Illumina microarrays.
Project description:Tumor growth is associated with a profound alteration of myelopoiesis, leading to recruitment of immunosuppressive cells known as myeloid-derived suppressor cells (MDSCs). Analyzing the cytokines affecting myelo-monocytic differentiation produced by various experimental tumors, we found that GM-CSF, G-CSF, and IL-6 allowed a rapid generation of MDSCs from precursors present in mouse and human bone marrow (BM). BM-MDSCs induced by GM-CSF+IL-6 possessed the highest tolerogenic activity, as revealed by the ability to impair the priming of IFN- -producing CD8+ T cells upon in vivo adoptive transfer. Moreover, adoptive transfer of syngeneic, GM-CSF+IL-6-conditioned MDSCs to diabetic mice transplanted with allogeneic pancreatic islets resulted in long term acceptance of the allograft and correction of the diabetic status. Cytokines inducing MDSCs acted on a common molecular pathway. Immunoregulatory activity of both tumor-induced and BM-derived MDSCs was entirely dependent on C/EBP transcription factor, a key component of the emergency myelopoiesis triggered by stress and inflammation. Adoptive transfer of tumor antigen-specific CD8+ T lymphocytes resulted in therapy of established tumors only in mice lacking C/EBP in myeloid compartment. These data unveil another link between inflammation and cancer and identify a novel molecular target to control tumor-induced immune suppression. We used gene expression analysis to identify those factors, secreted by tumor-infiltrating MDSC, which could drive emathopoiesis. Moreover we compare gene expression profile of tumor-induced MDSC, obtained from either the spleen and the tumor infiltrate of tumor bearing mice, and in vitro bone marrow-derived MDSC. CD11b+ cells were immunomagnetically enriched from various murine tissue and experimental conditions, and cRNA samples were prepared accordingly to Expression Analysis: Technical Manual. 701021 Rev. 5. Santa Clara, CA, Affymetrix; 2004, and hybridized to the Affymetrix GeneChip MOE430 2.0 array which contains more than 45,000 probe sets, representing more than 34,000 genes. CD11b+ cells obtained from the spleen of healthy BALB/c and C57BL/6 mice were used as reference sample for tumor induced CD11b+ MDSC, enriched from either the spleen and the tumor infiltrate of tumor-bearing mice. Moreover CD11b+ cells enriched from fresh bone marrow were used as reference sample for in vitro bone marrow-differentiated MDSC, obtained with either GM-CSF+IL-6 and GM-CSF+G-CSF 4 days cytokine cocktail treatment.
Project description:CD11b+ myeloid-derived suppressor cells (MDSCs) have been shown to become activated at the tumor site and acquired a more suppressive phenotype compared to the splenic counterpart. This activated status promotes cancer progression by creating an immune suppressive niche around the tumor, by providing nourishment to the neoplastic cells, and by promoting metastases. To start understanding the differences between splenic and tumor infiltrating CD11b, genome-wide transcriptome analysis was performed. We used gene expression analysis to identify those factors, secreted by tumor-infiltrating MDSC, which could drive emathopoiesis. Moreover, we compare gene expression profile of tumor-induced MDSC, obtained from either the spleen or the tumor infiltrate of tumor-bearing mice.
Project description:Myeloid derived suppressor cells (MDSC) in the tumor microenvironment suppress T-cell mediated immune surveillance that clears tumor cells. As such, MDSC promote tumor growth. There are two subtypes of tumor MDSC, CD11b+Ly6ChiLy6G- monocytic MDSC (M-MDSC) , and CD11b+Ly6ClowLy6Ghigh granulocytic MDSC (G-MDSC). Cells with these markers also exist in the spleen of tumor bearing mice or in the spleen of mice with tissue-specific inflammation. Some have argued that the tumor MDSC is an activated version of the spleen MDSC, implying that they are similar to one another. Here we isolated the MDSC subtypes from the RM-1 tumors and from the spleen of mice with prostatic inflammation (n=4 per subtype per tissue, 16 total samples). We then analyzed RNA from these cells to determine how the transcript profile was altered by tissue location and MDSC subtype. Platform: Affymetrix Mouse Gene 1.0 ST v1 Genechip
Project description:Tumors engender an environment dominated by M2 differentiated tumor macrophages that support tumor invasion, metastases and escape from immune control. In this study, we demonstrate that following radiation therapy of tumors in mice there is an influx of tumor macrophages that polarize towards wound repair and immune suppression. To investigate changes in the phenotype of tumor macrophages following radiation therapy, we FACS sorted tumor macrophages from Panc02 tumors. We have previously shown that we can distinguish mature tumor macrophages from immature myeloid and MDSC populations by expression of Gr1 and IA (MHC class II). To isolate these sub-populations, we first gated CD11b+ cells in the untreated or irradiated tumors, then sorted the CD11b+IA+ macrophage population and the CD11b+Gr1hi MDSC population. Cytospins of the sorted populations demonstrates that the CD11b+Gr1hi MDSC predominantly have a granulocyte morphology and the CD11b+IA+ cells have a macrophage morphology in both the untreated and irradiated tumors. RNA was purified from CD11b+IA+ macrophages from untreated or irradiated tumors 1 day or 7 days following radiation therapy and Gene Expression Microarray analysis was performed.