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Immunoregulatory actions of epithelial cell PPAR gamma at the colonic mucosa of mice with experimental inflammatory bowel disease.

ABSTRACT: BACKGROUND: Peroxisome proliferator-activated receptors are nuclear receptors highly expressed in intestinal epithelial cells (IEC) and immune cells within the gut mucosa and are implicated in modulating inflammation and immune responses. The objective of this study was to investigate the effect of targeted deletion of PPAR gamma in IEC on progression of experimental inflammatory bowel disease (IBD). METHODOLOGY/PRINCIPAL FINDINGS: In the first phase, PPAR gamma flfl; Villin Cre- (VC-) and PPAR gamma flfl; Villin Cre+ (VC+) mice in a mixed FVB/C57BL/6 background were challenged with 2.5% dextran sodium sulfate (DSS) in drinking water for 0, 2, or 7 days. VC+ mice express a transgenic recombinase under the control of the Villin-Cre promoter that causes an IEC-specific deletion of PPAR gamma. In the second phase, we generated VC- and VC+ mice in a C57BL/6 background that were challenged with 2.5% DSS. Mice were scored on disease severity both clinically and histopathologically. Flow cytometry was used to phenotypically characterize lymphocyte and macrophage populations in blood, spleen and mesenteric lymph nodes. Global gene expression analysis was profiled using Affymetrix microarrays. The IEC-specific deficiency of PPAR gamma in mice with a mixed background worsened colonic inflammatory lesions, but had no effect on disease activity (DAI) or weight loss. In contrast, the IEC-specific PPAR gamma null mice in C57BL/6 background exhibited more severe inflammatory lesions, DAI and weight loss in comparison to their littermates expressing PPAR gamma in IEC. Global gene expression profiling revealed significantly down-regulated expression of lysosomal pathway genes and flow cytometry results demonstrated suppressed production of IL-10 by CD4+ T cells in mesenteric lymph nodes (MLN) of IEC-specific PPAR gamma null mice. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that adequate expression of PPAR gamma in IEC is required for the regulation of mucosal immune responses and prevention of experimental IBD, possibly by modulation of lysosomal and antigen presentation pathways.

SUBMITTER: Mohapatra SK

PROVIDER: S-EPMC2857885 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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Immunoregulatory actions of epithelial cell PPAR gamma at the colonic mucosa of mice with experimental inflammatory bowel disease.

Mohapatra Saroj K SK Guri Amir J AJ Climent Montse M Vives Cristina C Carbo Adria A Horne William T WT Hontecillas Raquel R Bassaganya-Riera Josep J

PloS one 20100420 4

<h4>Background</h4>Peroxisome proliferator-activated receptors are nuclear receptors highly expressed in intestinal epithelial cells (IEC) and immune cells within the gut mucosa and are implicated in modulating inflammation and immune responses. The objective of this study was to investigate the effect of targeted deletion of PPAR gamma in IEC on progression of experimental inflammatory bowel disease (IBD).<h4>Methodology/principal findings</h4>In the first phase, PPAR gamma flfl; Villin Cre- (V ...[more]

PMID: 20422041

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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).

Dataset Information

Immunoregulatory actions of epithelial cell PPAR gamma at the colonic mucosa of mice with experimental inflammatory bowel disease.

Publications

Immunoregulatory actions of epithelial cell PPAR gamma at the colonic mucosa of mice with experimental inflammatory bowel disease.

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