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Transcriptome analysis of TNFR1-knockout mouse colon

ABSTRACT: We have compared mRNA expression in full-thickness mouse colon between wildtype mice and mice with a genetic deletion in tumor necrosis factor receptor 1 (TNFR1, encoded by the Tnfrsf1a gene). This experiment was motivated by our observation that Il10-/- Tnfr1-/- double-knockout mice develop very-early-onset colitis at the time of weaning, significantly earlier than disease onset in Il10-/- single-knockout mice. This suggests that TNFR1 mediates protection from colitis. To understand these protective mechanisms at the transcript level in a non-inflammatory context, we performed transcriptome profiling (mRNA-Seq) on colons from 12-week-old Tnfr1-/- mice, which do not develop colitis, and wildtype littermates. These experiments revealed that an estimated 510 transcripts were upregulated and 377 downregulated in colonic tissue of Tnfr1-/- mice. We aggregated the transcript information to calculate gene expression and performed gene set enrichment analysis to identify signaling pathways altered in Tnfr1-/- mice. When queried against a high-confidence set of 50 signaling pathways, the Tnfr1-/- gene expression profile was associated with reduced mitosis and increased glycolysis, transforming growth factor beta signaling, DNA repair, and reactive oxygen species signaling. Gene ontological analysis classified some of the differentially expressed genes into cytokines, junctional proteins, and transcription factors, but within these groups there was no consensus on the direction of regulation. We also examined how differentially expressed transcripts (called the TNFR1-regulated transcriptome) compared to differentially expressed colonic transcripts from previously collected Tnfr2-/- animals (or the TNFR2-regulated transcriptome, available at the NCBI Gene Expression Omnibus under the accession GSE65408). The raw data were re-analyzed with the current pipeline to enable comparison. There was almost no correlation between TNFR1- and TNFR2-regulated transcripts. Only 30 (~3%) TNFR1-regulated transcripts were also TNFR2-regulated transcripts, and ~4% of the TNFR2-regulated genes were also TNFR1-regulated genes. Of the few co-regulated transcripts, there was a significant negative correlation in their direction of regulation in Tnfr1-/- versus Tnfr2-/- colons. Collectively these results indicate that TNFR1 and TNFR2 have mostly different and opposing effects on gene expression in the mouse colon. MANUSCRIPT ABSTRACT: BACKGROUND & AIMS: Very-early-onset inflammatory bowel disease (VEO-IBD) is a devastating disease beginning in early childhood, refractory to anti-tumor necrosis factor (anti-TNF) therapies, and associated with mutations in the interleukin 10 (IL-10) pathway. Contrary to mainstream clinical practice, cellular and animal studies have shown beneficial roles of TNF signaling in colitis, but how these roles are encoded through TNF’s receptors remains unknown. Here we examined the role of TNF receptor 1 (TNFR1, or p55) in modulating the onset and severity of colitis in the interleukin 10 (IL-10)-deficient mouse model. METHODS: Colitis severity was compared between Il10-/- Tnfr1-/- and Il10-/-- littermate mice at 2-12 weeks of age. To assess dysbiosis as a potential pathogenic mechanism, Il10-/- Tnfr1-/- mice were treated with neomycin and metronidazole and their cecal contents analyzed by 16S rRNA sequencing. Gene expression, barrier function, and epithelial proliferation and apoptosis were examined in adult colitis-free Tnfr1-/- wildtype littermates. RESULTS: In contrast to relatively healthy Il10-/- mice, Il10-/- Tnfr1-/- mice developed severe, antibiotic-treatable colitis shortly after weaning. Microbiotal composition was similar between Il10‑/- Tnfr1-/- mice and Il10-/- littermate controls. Tnfr1-/- mice expressed transcripts associated with reactive oxygen species and DNA repair pathways. Tnfr1-/- mice exhibited focal areas of crypt branching, higher colonic epithelial permeability, and hallmarks of DNA damage. CONCLUSIONS: TNFR1 promotes epithelial homeostasis and regulates commensal exposure. The lack of TNFR1 accelerates the onset and severity of IBD in the absence of tolerogenic signaling (i.e., lack of IL-10). Il10-/- Tnfr1-/- mice may serve as a valuable model of very-early-onset IBD (VEO-IBD).

ORGANISM(S): Mus musculus

PROVIDER: GSE107933 | GEO | 2019/03/15

REPOSITORIES: GEO

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Project description:PURPOSE: The goal of this study was to determine the gene expression networks regulated by tumor necrosis factor receptor 2 (TNFR2, or Tnfrsf1b) and to evaluate their potential bearing on immune cell subsets and inflammatory bowel disease (IBD). METHODS: mRNA-seq was performed on isolated distal colons from TNFR2-knockout and wildtype mice. Differentially expressed transcripts were compared to human ulcerative colitis microarray datasets on Gene Expression Omnibus and to mouse immunological expression datasets at the Immunological Genome Project. RESULTS: We identified 252 mouse transcripts whose expressions were significantly altered by the loss of TNFR2. The majority of these transcripts (228 of 252, ~90%) were downregulated in TNFR2-/- colons. TNFR2-regulated genes were able to positively discriminate between ulcerative colitis patients and healthy individuals with ~80% accuracy. Many TNFR2-regulated genes were also highly expressed in CD8+ T cells. CONCLUSIONS: Downregulation of TNFR2 is associated with a gene expression profile that is prominent in IBD and supportive of the role of CD8+ T cells in IBD pathogenesis. MANUSCRIPT ABSTRACT: Increased tumor necrosis factor (TNF) production has been associated with inflammatory bowel disease (IBD), and anti-TNF therapy is a common therapeutic for this patient population. However, the role of TNF or its receptors (TNFR1 and TNFR2) in the immunopathogenesis of inflammatory bowel disease (IBD) remains unclear. Here we report that TNFR2 is protective in spontaneous (IL-10 knockout) and chemically (azoxymethane/dextran sodium sulfate)-induced mouse models of colitis and colitis-associated cancer. Mechanistically, TNFR2-deficiency in hematopoietic cells significantly increased incidence and severity of colitis and colitis-associated cancer characterized by a selective expansion of CD8+ T cells. We identified TNFR2-regulated genes in the colon that were specific for CD8+ T cells, interacted with multiple IBD risk genes, and are important regulators of CD8+ T cell biology. TNFR2 regulated CD8+ T-cell-specific genes that act as genetic susceptibility modifiers for IBD to mitigate the development of a pro-colitogenic milieu. Antibody-mediated depletion of CD8+ T cells prevented colonic inflammation and significantly reduced pathology in IL10-/-/TNFR2-/- deficient mice. Furthermore, adoptive transfer of TNFR2-/- naïve CD8+ T cells resulted in more severe disease than with wildtype naïve CD8+ T cells. Our findings provide insight into the disease modifier role of TNFR2 in the immunopathogenesis of IBD through the modulation of CD8+ T cell responses and support future investigation of this therapeutic target, especially in the subset of IBD patients with CD8+ T-cell dysfunction. Total RNA from distal colons of 8 week-old male wildtype C57Bl/6 and TNFR2-/- mice (n=3 each) was isolated using the PureLink RNA kit (Ambion, Life Technologies). RNA samples were submitted to the Genomic Services Lab at the HudsonAlpha Institute for Biotechnology (Huntsville, AL) for multiplex library preparation, mRNA enrichment, and sequencing. Sequencing was performed to an average depth of 50M paired-end 50bp reads per sample (HiSeq, Illumina, San Diego, CA). Data files containing raw reads were aligned to the mouse genome using Tophat2/Bowtie2. Alignments were assembled into transcript representations with Cufflinks, and statistical tests for differential expression were performed with Cuffdiff 2. An adjusted P value < 0.05 (q<0.05) from the Cuffdiff 2 output was used as the cutoff for statistical significance.

Project description:Background and Aims: In the interleukin-10-deficient (Il10-/-) mouse model of IBD, 10 quantitative trait loci (QTL) have been shown to be associated with colitis susceptibility by linkage analyses on experimental crosses of highly susceptible C3H/HeJBir (C3Bir)-Il10-/- and partially resistant C57BL/6J (B6)-Il10-/- mice. The strongest locus (C3Bir-derived cytokine deficiency-induced colitis susceptibility [Cdcs]1 on Chromosome [Chr] 3) controlled multiple colitogenic subphenotypes and contributed the vast majority to the phenotypic variance in cecum and colon. This was demonstrated by interval-specific Chr 3 congenic mice wherein defined regions of Cdcs1 from C3Bir or B6 were bred into the IL-10-deficient reciprocal background and altered the susceptible or resistant phenotype. Furthermore, this locus likely acts by inducing innate hypo- and adaptive hyperresponsiveness, associated with impaired NFΚB responses of macrophages. The aim of the present study was to dissect the complexity of Cdcs1 by further development and characterization of reciprocal Cdcs1 congenic strains and to identify potential candidate genes in the congenic interval. Material and Methods: In total, 15 reciprocal congenic strains were generated from Il10-/- mice of either C3H/HeJBir or C57BL/6J backgrounds by 10 cycles of backcrossing. Colitis activity was monitored by histological grading. Candidate genes were identified by fine mapping of congenic intervals, sequencing, microarray analysis and a high-throughput real-time RT-PCR approach using bone marrow-derived macrophages. Results: Within the originally identified Cdcs1-interval, three independent regions were detected that likely contain susceptibility-determining genetic factors (Cdcs1.1, Cdcs1.2, and Cdcs1.3). Combining results of candidate gene approaches revealed Fcgr1, Cnn3, Larp7, and Alpk1 as highly attractive candidate genes with polymorphisms in coding or regulatory regions and expression differences between susceptible and resistant mouse strains. Conclusions: Subcongenic analysis of the major susceptibility locus Cdcs1 on mouse chromosome 3 revealed a complex genetic structure. Candidate gene approaches revealed attractive genes within the identified regions with homologs that are located in human susceptibility regions for IBD. Experiment Overall Design: Bone marrow derived macrophages (BMDM) of colitis susceptible C3Bir-Il10-/- and colitis resistant B6-Il10-/- as well as the Il10-/- reciprocal congenic strains CB-R1 (C3Bir genetic background carrying a long congenic chromosome 3 element containing Cdcs1 from B6, rendering this formerly susceptible background resistant) and BC-R3 (B6 genetic background that carries the Cdcs1-region of C3Bir) were cultured and stimulated with flagellin or left unstimulated. BMDM were obtained from 3 male mice per genotype and cultured in polystyrene 6-well culture plates. Before RNA-isolation, 3 wells per plate were stimulated with Cbir1 flagellin (and subsequently pooled for RNA isolation), the other 3 wells left unstimulated (and also pooled). In total, these experiments were replicated three times in order to perform microarray analyses in triplicates.

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Transcriptome analysis of TNFR1-knockout mouse colon

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