Project description:Caspase-8 is a cystein protease involved in regulating apoptosis. The function of caspase-8 was studied in the intestinal epithelium, using mice with an intestinal epithelial cell specific deletion of caspase-8. We used microarrays to investigate the difference of the global programme of gene expression in intestinal epithelial cells of control and caspase-8 deficient mice. Intestinal epithelial cells were isolated from 3 control mice and 3 mice with a conditional deletion of caspase-8 in the intestinal epithelium. RNA was isolated and subjected to Affymetrix gene chip analysis.
Project description:Caspase-8 is a cystein protease involved in regulating apoptosis. The function of caspase-8 was studied in the intestinal epithelium, using mice with an intestinal epithelial cell specific deletion of caspase-8. We used microarrays to investigate the difference of the global programme of gene expression in intestinal epithelial cells of control and caspase-8 deficient mice.
Project description:In the present study, we demonstrated that mice deficient in chemerin or IEC-specific CMKLR1 expression were highly susceptible to DSS-induced colitis and subsequent tumorigenesis, which was reversed by suppressing colonic neutrophilic inflammation using CXCR2 inhibitor. Surprisingly, we found that lack of the Chemerin-CMKLR1 signaling specifically reduced colonic epithelial expression of lactoperoxidase (LPO), an epithelial peroxidase which could utilize H2O2 to oxidase thiocyanates to antibiotic compound (Bafort et al., 2014). Importantly, we demonstrated that impaired epithelial LPO expression accounted for outgrowth of potentially pathogenic Gram-negative bacteria following epithelial injury, which led to overproduction of CXCL1/2 and pathological neutrophilic inflammation in mice with epithelial Chemerin-CMKLR1 signaling deficiency. Finally, lack of epithelial Chemerin-CMKLR1 signaling impaired early host defense against enteric bacteria, which was reversed by LPO supplementation. Taken together, our study uncovers a critical role of epithelial Chemerin-CMKLR1 signaling in restricting pathological colonic neutrophilia via potentiating LPO-mediated epithelial innate defense, thereby rendering protection against microbiota-driven colitis and tumorigenesis.
Project description:Purpose: The objective of this study is to compare the transcriptome profile of intestinal epithelial organoids cultivated from distal colon tissue of patients with ulcerative colitis vs organoids cultivate from non-matched and otherwise healthy patient colon
Project description:Histone deacetylases (Hdac) remove acetyl groups from proteins, influencing global and specific gene expression. Hdacs control inflammation, as shown by Hdac inhibitor-dependent protection from DSS-induced murine colitis. While tissue-specific Hdac knockouts show redundant and specific functions, little is known of their intestinal epithelial cell (IEC) role. We have shown previously that dual Hdac1/Hdac2 IEC-specific loss disrupts cell proliferation and determination, with decreased secretory cell numbers and altered barrier function. We thus investigated how compound Hdac1/Hdac2 or Hdac2 IEC-specific deficiency alters the inflammatory response. Floxed Hdac1 and Hdac2 and villin-Cre mice were interbred. Compound Hdac1/Hdac2 IEC-deficient mice showed chronic basal inflammation, with increased basal Disease Activity Index (DAI) and deregulated Reg gene colonic expression. DSS-treated dual Hdac1/Hdac2 IEC-deficient mice displayed increased DAI, histological score, intestinal permeability and inflammatory gene expression. In contrast to double knockouts, Hdac2 IEC-specific loss did not affect IEC determination and growth, nor result in chronic inflammation. However, Hdac2 disruption protected against DSS colitis, as shown by decreased DAI, intestinal permeability and caspase-3 cleavage. Hdac2 IEC-specific deficient mice displayed increased expression of IEC gene subsets, such as colonic antimicrobial Reg3b and Reg3g mRNAs, and decreased expression of immune cell function-related genes. Our data show that Hdac1 and Hdac2 are essential IEC homeostasis regulators. IEC-specific Hdac1 and Hdac2 may act as epigenetic sensors and transmitters of environmental cues and regulate IEC-mediated mucosal homeostatic and inflammatory responses. Different levels of IEC Hdac activity may lead to positive or negative outcomes on intestinal homeostasis during inflammation Total RNAs from the colon of three control and three Hdac2 IEC-specific knockout mice were isolated with the Rneasy kit (Qiagen, Mississauga, ON, Canada).
Project description:Inflammatory caspases are essential effectors of inflammation and cell death. Here, we investigated their roles in colitis and colorectal cancer and report a bimodal regulation of intestinal homeostasis, inflammation and tumorigenesis by caspases-1 and -12. Casp1-/- mice exhibited defects in mucosal tissue repair and succumbed rapidly after dextran sulfate sodium (DSS) administration. This phenotype was rescued by administration of exogenous interleukin-18 and was partially reproduced in mice deficient in the inflammasome adaptor ASC. Casp12-/- mice, in which the inflammasome is derepressed, were resistant to acute colitis and showed signs of enhanced repair. Together with their increased inflammatory response, the enhanced repair response of Casp12-/- mice rendered them more susceptible to colorectal cancer induced by azoxymethane (AOM)+DSS. Taken together, our results indicate that the inflammatory caspases are critical in the induction of inflammation in the gut following injury, which is necessary for tissue repair and maintenance of immune tolerance. Total RNA obtained from isolated tumors or normal colon tissue from wild type and caspase-12 deficient mice were compared.
Project description:Animal models for targeted cell ablation are invaluable in the field of biology and medicine. Specifically, fetal targeted cell ablation has the potential for organ regeneration and xenotransplantation. Previous methods involve conventional knockout models, which offers limited control over severity, or conditional ablation models, which use inducers that are harmful to fetuses. In this study, we apply the inducible caspase 9 (iC9) system to target mouse fetal nephron progenitor cells. It triggers specific, rapid, and efficient target cell ablation through the intrinsic apoptosis pathway by the administration of a safe, placental-permeable inducer. This feature allowed for precise adjustment of severity based on the timing of administration, enabling the creation of a viable severe kidney failure model. We also demonstrate that cells with low iC9 expression levels and those in the solid organ state are less susceptible to apoptosis induction. RNA-seq of wild type mouse fetal kidneys revealed that DNA damage response is enhanced after dissociation, suggesting that it is the underlying mechanism for the reduced susceptibility to apoptosis in solid-state cells compared to single-cell states. Apoptosis can still be triggered in these conditions by the combined inhibition of X-linked inhibitor of apoptosis protein. This approach will not only facilitate the study of mechanisms involved in induced cell death but also enhance its utility as a research tool, including for fetal organ transplantation models.
Project description:Recruited blood monocytes contribute to the establishment, perpetuation and resolution of tissue inflammation. Specifically, in the inflamed intestine, monocyte ablation was shown to ameliorate colitis scores in preclinical animal models. However, the majority of intestinal macrophages that seed the healthy gut are also monocyte-derived. Monocyte ablation aimed to curb inflammation would therefore likely interfere with intestinal homeostasis. Here, we used a TLR2 trans-membrane peptide which blocks TLR2 dimerization that is critical for TLR2 /1 and TLR2 / 6 heterodimer signaling to blunt inflammation in a murine colitis model. We show that while the TLR2 peptide treatment ameliorated colitis, it allowed recruited monocytes to give rise to macrophages that lack the detrimental pro-inflammatory gene signature and reduced potentially damaging neutrophils infiltrates. Finally, we demonstrate TLR blocking activity of the peptide on in vitro cultured human monocyte-derived macrophages. Collectively, we provide a significantly improved anti-inflammatory TLR2 peptide and critical insights in its mechanism of action towards future potential use in the clinic.
Project description:Histone deacetylases (Hdac) remove acetyl groups from proteins, influencing global and specific gene expression. Hdacs control inflammation, as shown by Hdac inhibitor-dependent protection from DSS-induced murine colitis. While tissue-specific Hdac knockouts show redundant and specific functions, little is known of their intestinal epithelial cell (IEC) role. We have shown previously that dual Hdac1/Hdac2 IEC-specific loss disrupts cell proliferation and determination, with decreased secretory cell numbers and altered barrier function. We thus investigated how compound Hdac1/Hdac2 or Hdac2 IEC-specific deficiency alters the inflammatory response. Floxed Hdac1 and Hdac2 and villin-Cre mice were interbred. Compound Hdac1/Hdac2 IEC-deficient mice showed chronic basal inflammation, with increased basal Disease Activity Index (DAI) and deregulated Reg gene colonic expression. DSS-treated dual Hdac1/Hdac2 IEC-deficient mice displayed increased DAI, histological score, intestinal permeability and inflammatory gene expression. In contrast to double knockouts, Hdac2 IEC-specific loss did not affect IEC determination and growth, nor result in chronic inflammation. However, Hdac2 disruption protected against DSS colitis, as shown by decreased DAI, intestinal permeability and caspase-3 cleavage. Hdac2 IEC-specific deficient mice displayed increased expression of IEC gene subsets, such as colonic antimicrobial Reg3b and Reg3g mRNAs, and decreased expression of immune cell function-related genes. Our data show that Hdac1 and Hdac2 are essential IEC homeostasis regulators. IEC-specific Hdac1 and Hdac2 may act as epigenetic sensors and transmitters of environmental cues and regulate IEC-mediated mucosal homeostatic and inflammatory responses. Different levels of IEC Hdac activity may lead to positive or negative outcomes on intestinal homeostasis during inflammation