Project description:BACKGROUND AND AIMS: Loss of epithelial cell homeostasis and apoptosis highly con-tribute to intestinal inflammation. While endoplasmic reticulum unfolded protein response (UPR) has been implicated in chronic intestinal inflammation, functional correlation between UPR-related C/EBP homologous protein (CHOP) expression and CHOP-mediated programming towards inflammation-related disease susceptibility remains unclear. In this study, we generated the new mouse model ChopIEC Tg/Tg to investigate consequences of intestinal epithelial cell (IEC)-specific CHOP overexpression. Transcriptional profiling of transgenic mice identified a set of CHOP-dependent target genes related to inflammatory and microbial defense program in the intestinal epithelium. Effect of CHOP overexpression in intestial epithelial cells was investigated on epithelial homeostasis using transgenic mice Disease-free mice do not show enhanced apoptotic signaling Intestinal epithelial cells were isolated from 12 week old females
Project description:The development and severity of inflammatory bowel diseases (IBD) and other chronic inflammatory conditions can be influenced by host genetic and environmental factors, including signals derived from commensal bacteria. However, the mechanisms that integrate these diverse cues remain undefined. Here we demonstrate that intestinal epithelial cells (IECs) isolated from IBD patients exhibit decreased expression of the epigenome-modifying enzyme histone deacetylase 3 (HDAC3). Further, genome-wide analyses of murine IECs that lack HDAC3 (HDAC3ΔIEC) revealed that HDAC3 deficiency resulted in dysregulated gene expression coupled with alterations in histone acetylation. Critically, conventionally-housed HDAC3ΔIEC mice demonstrated loss of Paneth cells, impaired IEC function and alterations in the composition of intestinal commensal bacteria. In addition, HDAC3ΔIEC mice exhibited significantly increased susceptibility to intestinal damage and inflammation, indicating that epithelial expression of HDAC3 plays a central role in maintaining intestinal homeostasis. Strikingly, rederivation of HDAC3ΔIEC mice into germ-free conditions revealed that dysregulated IEC gene expression, Paneth cell homeostasis, and intestinal barrier function were largely restored in the absence of commensal bacteria. Collectively, these data indicate that the HDAC3 is a critical factor that integrates commensal bacteria-derived signals to calibrate epithelial cell responses required to establish normal host-commensal relationships and maintain intestinal homeostasis. Analyses of histone acetylation in primary IECs from HDAC3FF (3 biologic replicates) and HDAC3ΔIEC (3 biologic replicates) mice were conducted utilizing ChIP-seq for H3K9Ac.
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:During ageing, cell-intrinsic and extrinsic factors lead to the decline of tissue function and organismal health. Disentangling these factors is important for developing effective strategies to prolong organismal healthspan. Here, we addressed this question in the mouse intestinal epithelium, which forms a dynamic interface with its microenvironment and receives extrinsic signals affecting its homeostasis and tissue ageing. We systematically compared transcriptional profiles of young and aged epithelial cells in vivo and ex vivo in cultured intestinal organoids. We found that all cell types of the aged epithelium exhibit an inflammation phenotype, which is marked by MHC class II upregulation and most pronounced in enterocytes. This was accompanied by elevated levels of the immune tolerance markers PD-1 and PD-L1 in the aged tissue microenvironment, indicating dysregulation of immunological homeostasis. Intestinal organoids from aged mice still showed an inflammation signature after weeks in culture, which was concurrent with increased chromatin accessibility of inflammation-associated loci. Our results reveal a cell-intrinsic, persistent inflammation phenotype in aged epithelial cells, which might contribute to systemic inflammation observed during ageing.
Project description:BACKGROUND AND AIMS: Loss of epithelial cell homeostasis and apoptosis highly con-tribute to intestinal inflammation. While endoplasmic reticulum unfolded protein response (UPR) has been implicated in chronic intestinal inflammation, functional correlation between UPR-related C/EBP homologous protein (CHOP) expression and CHOP-mediated programming towards inflammation-related disease susceptibility remains unclear. In this study, we generated the new mouse model ChopIEC Tg/Tg to investigate consequences of intestinal epithelial cell (IEC)-specific CHOP overexpression. Transcriptional profiling of transgenic mice identified a set of CHOP-dependent target genes related to inflammatory and microbial defense program in the intestinal epithelium.
Project description:The small intestinal epithelial barrier inputs signals from the gut microbiota in order to balance physiological inflammation and tolerance, and to promote homeostasis. Understanding the dynamic relationship between microbes and intestinal epithelial cells has been a challenge given the cellular heterogeneity associated with the epithelium and the inherent difficulty of isolating and identifying individual cell types. Here, we used single-cell RNA sequencing of small intestinal epithelial cells from germ-free and specific pathogen-free mice to study microbe-epithelium crosstalk at the single cell resolution.
Project description:We generated a novel Six2-Cre+/-PKAcaRfl/wt (CA-PKA) CA-PKA mouse in which expression of constitutive-active PKAcaR was induced in gastric mesenchyme progenitors. CA-PKA mice showed disruption of gastric homeostasis characterized by aberrant mucosal development and epithelial hyperproliferation; ultimately developing multiple features of gastric corpus preneoplasia including decreased parietal cells, mucous cell hyperplasia, spasmolytic peptide expressing metaplasia (SPEM) with intestinal characteristics and dysplastic and invasive cystic glands. Our results show that constitutively active PKAcaR in the stomach mesenchyme nonautonomously disrupts gastric homeostasis characterized by increased epithelial proliferation and aberrant epithelial maldevelopment, ultimately leading to gastric preneoplasia.
Project description:The development and severity of inflammatory bowel diseases (IBD) and other chronic inflammatory conditions can be influenced by host genetic and environmental factors, including signals derived from commensal bacteria. However, the mechanisms that integrate these diverse cues remain undefined. Here we demonstrate that intestinal epithelial cells (IECs) isolated from IBD patients exhibit decreased expression of the epigenome-modifying enzyme histone deacetylase 3 (HDAC3). Further, genome-wide analyses of murine IECs that lack HDAC3 (HDAC3ΔIEC) revealed that HDAC3 deficiency resulted in dysregulated gene expression coupled with alterations in histone acetylation. Critically, conventionally-housed HDAC3ΔIEC mice demonstrated loss of Paneth cells, impaired IEC function and alterations in the composition of intestinal commensal bacteria. In addition, HDAC3ΔIEC mice exhibited significantly increased susceptibility to intestinal damage and inflammation, indicating that epithelial expression of HDAC3 plays a central role in maintaining intestinal homeostasis. Strikingly, rederivation of HDAC3ΔIEC mice into germ-free conditions revealed that dysregulated IEC gene expression, Paneth cell homeostasis, and intestinal barrier function were largely restored in the absence of commensal bacteria. Collectively, these data indicate that the HDAC3 is a critical factor that integrates commensal bacteria-derived signals to calibrate epithelial cell responses required to establish normal host-commensal relationships and maintain intestinal homeostasis. In this study, we performed gene expression profiling to examine how the transcriptional profiles in primary live, EpCAM+ IECs from the large intestine differed between germ-free control HDAC3FF mice (3 biological replicates) and germ-free IEC-intrinsic knockout HDAC3ΔIEC mice (3 biological replicates).
Project description:The development and severity of inflammatory bowel diseases (IBD) and other chronic inflammatory conditions can be influenced by host genetic and environmental factors, including signals derived from commensal bacteria. However, the mechanisms that integrate these diverse cues remain undefined. Here we demonstrate that intestinal epithelial cells (IECs) isolated from IBD patients exhibit decreased expression of the epigenome-modifying enzyme histone deacetylase 3 (HDAC3). Further, genome-wide analyses of murine IECs that lack HDAC3 (HDAC3?IEC) revealed that HDAC3 deficiency resulted in dysregulated gene expression coupled with alterations in histone acetylation. Critically, conventionally-housed HDAC3?IEC mice demonstrated loss of Paneth cells, impaired IEC function and alterations in the composition of intestinal commensal bacteria. In addition, HDAC3?IEC mice exhibited significantly increased susceptibility to intestinal damage and inflammation, indicating that epithelial expression of HDAC3 plays a central role in maintaining intestinal homeostasis. Strikingly, rederivation of HDAC3?IEC mice into germ-free conditions revealed that dysregulated IEC gene expression, Paneth cell homeostasis, and intestinal barrier function were largely restored in the absence of commensal bacteria. Collectively, these data indicate that the HDAC3 is a critical factor that integrates commensal bacteria-derived signals to calibrate epithelial cell responses required to establish normal host-commensal relationships and maintain intestinal homeostasis. In this study, we performed gene expression profiling to examine how the transcriptional profiles in primary live, EpCAM+ IECs from the large intestine differed between control HDAC3FF mice (3 biological replicates) and IEC-intrinsic knockout HDAC3?IEC mice (3 biological replicates).
Project description:The intestinal epithelium is a key physical interface that integrates dietary and microbial signals to regulate nutrient uptake and mucosal homeostasis. Intestinal epithelial cells (IECs) have a high turnover rate driven by the death of terminally differentiated cells with concurrent stem cell proliferation, a process critical for maintaining intestinal homeostasis and protecting against mucosal inflammation. The transcriptional programs that regulate IEC quiescence, proliferation, and differentiation have been well-characterized. However, how gene expression networks critical for IEC functions are regulated at the post-transcriptional level during homeostasis or inflammatory disease remains poorly understood. Herein, we show that a conserved family of microRNAs, miR-181, is significantly downregulated in IECs from patients with inflammatory bowel disease and mice with chemical-induced colitis. Strikingly, we showed that miR-181 expression within IECs, but not the hematopoietic system, is required for protection against the development of severe colonic inflammation in response to epithelial injury in mice. Mechanistically, we showed that miR-181 expression increases the proliferative capacity of IECs, likely through the regulation of Wnt signaling, independently of gut microbiota composition. As epithelial reconstitution is crucial for restoring intestinal homeostasis after injury, the miR-181 family represents a potential novel therapeutic target in IECs for protection against severe intestinal inflammation.