Unknown,Transcriptomics,Genomics,Proteomics

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DICER controls macrophage polarization and tumor response to immunotherapy

ABSTRACT: Tumor-associated macrophages (TAMs) have immunosuppressive capacity in mouse models of cancer. Here we show that the genetic deletion of the microRNA (miRNA)-processing enzyme DICER in TAMs broadly programs them to a CD11c+MRC1â/low M1-like immunostimulatory phenotype characterized by activated interferon-Î³ (IFN-Î³)/STAT1/IRF signaling. M1-like TAM programming fostered the recruitment of cytotoxic T-cells (CTLs), including tumor-antigen-specific CTLs, inhibited tumor growth, and enhanced the efficacy of PD1 checkpoint blockade. Bioinformatics analysis of TAM transcriptomes identified a limited set of miRNAs putatively involved in TAM programming. Re-expression of Let-7 in Dicer-deficient TAMs was sufficient to partly rescue the M2-like (protumoral) TAM phenotype and abate tumor CTL infiltration. Targeted suppression of DICER activity in TAMs may, therefore, stimulate antitumor immunity and enhance the efficacy of cancer immunotherapy. To explore the role of DICER in the development, activation and immunological functions of TAMs, we crossed homozygous LysM-Cre (Clausen et al., 1999) with Dicerlox/lox (Harfe et al., 2005) mice to obtain mice with myeloid-cell-specific Dicer1 gene deletion (LysM-Cre;Dicerâ/â, referred to as Dâ/â). These mice were then backcrossed to LysM-Cre to obtain the control LysM-Cre; Dicer+/+ mice (referred to as D+/+). Both LysM-Cre and Dicerlox/lox mutations were always homozygous in our experiment. We then inoculated Lewis lung carcinoma (LLC) cells subcutaneously (s.c.) in Dâ/â and control D+/+ mice. Once the tumors were established, we isolated by fluorescence-activated cell sorting (FACS) tumor-associated macrophages (F4/80+ cells).

ORGANISM(S): Mus musculus

SUBMITTER: Chia-Huey Ooi

PROVIDER: E-GEOD-76356 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Inflammatory bowel disease (IBD) is a condition characterized by severe intestinal inflammation and immune cell activation. The severity of the disease can be mitigated by compounds which activate peroxisome proliferator-activated receptor gamma (PPAR gamma), a receptor present widely in tissues involved in IBD pathogenesis. Our objective was to assess the affect of macrophage-specific deficiency of PPAR gamma on peripheral and colonic immune populations and colonic gene expression in experimental IBD. Macrophage-specific PPAR gamma-deficient mice (PPAR gamma flfl Lysozyme M Cre+) and control (PPAR gamma flfl Lysozyme M Cre-) littermates were treated with 2.5% dextran sodium sulfate (DSS) for 7 days. Disease activity was recorded daily and immune cell populations in the blood, spleen, mesenteric lymph nodes (MLN), and lamina propria were examined by flow cytometry. Colonic gene expression was assessed by real time PCR and microarray analyses. Our findings show that macrophage PPAR r-deficiency significantly exacerbates DSS inflammation. CD4+CD25+FoxP3+ regulatory T cells (T-regs) were significantly reduced in Cre+ mice, and MLN macrophages and CD40 expression were enhanced. There were significant differences in the number colonic macrophages between Cre+ and Cre- mice, but those from Cre+ mice expressed more CD40, Ly6C, and TLR-4. PPAR r-deficiency also increased the percent of CD8+ T cells in the lamina propria and enhanced colonic interferon gamma expression. Our findings indicate that macrophage PPAR gamma deficiency augments the severity of DSS colitis by reducing peripheral T-regs and increasing colonic macrophage activation and T cell inflammation. RNA from 3 PPAR gamma-deficient mice (PPAR gamma flfl; Lysozyme M Cre+) and 3 control (PPAR gamma flfl; Lysozyme M Cre-) littermates was processed and labeled according to the standard target labeling protocols. The samples were hybridized, stained, and scanned per standard Affymetrix protocols at the Virginia Bioinformatics Institute (VBI) core laboratory on Mouse 430 2.0 expression arrays (Affymetrix Inc., Santa Clara, CA).

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DICER controls macrophage polarization and tumor response to immunotherapy

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