Unknown,Transcriptomics,Genomics,Proteomics

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Initiation of an inflammatory response in resident intestinal lamina propria cells -use of a human organ culture model

ABSTRACT: Resident human lamina propria immune cells serve as powerful effectors in host defense. Molecular events associated with the initiation of an intestinal inflammatory response in these cells are largely unknown. Here, we aimed to characterize phenotypic and functional changes induced in these cells at the onset of intestinal inflammation using a human intestinal organ culture model. In this model, healthy human colonic mucosa was depleted of epithelial cells by EDTA treatment. Following loss of the epithelial layer, expression of the inflammatory mediators IL-1β, IL-6, IL-8, IL-23p19, TNF-α, CXCL2 and the surface receptors CD14, TLR2, CD86, CD54 was rapidly induced in resident lamina propria cells in situ as determined by qRT-PCR and immunohistology. Gene microarray analysis of lamina propria cells obtained by laser-capture microdissection provided an overview of global changes in gene expression occurring during the initiation of an intestinal inflammatory response in these cells. Bioinformatic analysis gave insight into signalling pathways mediating this inflammatory response. Furthermore, comparison with published microarray datasets of inflamed mucosa in vivo (ulcerative colitis) revealed a significant overlap of differentially regulated genes underlining the in vivo relevance of the organ culture model. The organ culture model characterized may be useful to study molecular mechanisms underlying the initiation of an intestinal inflammatory response in normal mucosa as well as potential alterations of this response in inflammatory bowel disease. Gut specimens were derived from individuals undergoing resection for localized colon cancer. Microscopically normal colonic mucosa was dissected from the surgical specimen near the resection margin and immediately subjected to the experimental procedures. After extensive washing the mucus layer was removed by dithiothreitol (DTT) treatment. Subsequently, punches of defined surface area were prepared and denuded of epithelial cells by exposure to EDTA. Samples were collected prior to culturing and washing (control, t = 0 h, total mucosa, TM) as well as after loss of the epithelial layer (t = 5 h, mucosa after loss of epithelial layer, LEL-M) and snap frozen in liquid nitrogen. Lamina Propria (LP) was subsequently isolated via Laser Capture Microdissection (LMD) followed by RNA isolation. Microarray analysis of TM-LP (control) and LEL-LP samples was performed using the WG-DASL Human HT_12 V4 Expression BeadChip Assay from Illumina employing a minimum of 200 ng total RNA per sample. Four replicates from individual experiments were measured for each time point.

ORGANISM(S): Homo sapiens

SUBMITTER: Judith Gras

PROVIDER: E-GEOD-56448 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The microenvironment of injured mucosa has important effects on intestinal stem cell self-renewal and reconstruction of epithelial barrier function in inflammatory bowel disease (IBD). However, the precise status of the interactions between intestinal epithelial cell (IEC) injury, particularly intestinal crypt absence, and microenvironment in IBD is not completely understood. We identified miR-494-3p as important for protection of colonic stemness in intestinal inflammation colonic organoid culture. A novel cytokine-cytokine receptor, EDA-A2/EDA2R, could suppress colonic stemness and epithelial repair during IBD. During intestinal inflammation, high level of LP macrophage-derived EDA-A2 inhibited the nuclear β-catenin/c-Myc axis and organoid growth by targeting EDA2R in colonic crypt stem cells. We further demonstrated that the pro-inflammatory cytokines IL-1β and IL-6 are capable of stimulating macrophages to release EDA-A2 during colitis. Secondly, we identified the cross-talk among IECs, colonic crypts, and lamina propria (LP) macrophages in miR-494-3p-mediated colitis. Furthermore, our study showed that miR-494-3p deficiency in IECs promoted LP macrophage recruitment and M1 activation in DSS-induced colitis mice. In addition, we identified miR-494-3p as critical to dampening IEC injury; specifically, miR-494-3p inhibited inflammation-induced IKKβ/NF-κB activation by targeting the IKKβ 3’UTR in IECs. As such, administration of adequate amounts of a miR-494-3p agomire attenuate colitis in vivo. Consistent with this inference, we showed that miR-494-3p levels were decreased in colonic crypts and serum in colitis mice, and loss of miR-494 potentiated the severity of colonic colitis. Our clinical data on the interactions between miR-494-3p levels in serum exosomes & colonic tissues and associated outcomes support the clinical relevance of miR-494-3p in IBD. The miR-494-3p agomir system, which we designed permits local delivery in vivo in this study, significantly ameliorated the severity of colonic colitis. Our findings no only uncover a miR-494-3p-mediated cross-talk mechanism by which inflamed colonic LP macrophages integrate signals from IECs to regulate colonic stemness and colonic epithelial repair/homeostasis. The miR-494-3p agomir may serve as a potential therapeutic approach in IBD.

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Initiation of an inflammatory response in resident intestinal lamina propria cells -use of a human organ culture model

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