Intestinal Hyperplasia Research Articles

Drosophila PEBP1 inhibits intestinal stem cell aging via suppression of ERK pathway.

The intestine is a high cellular turnover tissue largely dependent on the regenerative function of stem cell throughout life, and a signaling center for the health and viability of organisms. Therefore, better understanding of the mechanisms underlying the regulation of intestinal stem cell (ISC) regenerative potential is essential for the possible intervention of aging process and age-related diseases. Drosophila midgut is a well-established model system for studying the mechanisms underlying ISC regenerative potential during aging. Here, we report the requirement of Drosophila phosphatidylethanolamine binding protein 1 (PEBP1) in ISC regenerative potential. We showed that PEBP1 was strongly expressed in enterocytes (ECs) of guts and its decrease with age and oxidative stress. Furthermore, the downregulation of PEBP1 in ECs accelerates ISC aging, as evidenced by ISC hyper-proliferation, γH2AX accumulation, and centrosome amplification, and intestinal hyperplasia. The decrease in PEBP1 expression was associated with increased extracellular signal-regulated kinase (ERK) activity in ECs. All these phenotypes by EC-specific depletion of PEBP1 were rescued by the concomitant inhibition of ERK signaling. Our findings evidence that the age-related downregulation of PEBP1 in ECs is a novel cause accelerating ISC aging and that PEBP1 is an EC-intrinsic suppressor of epidermal growth factor receptor (EGFR)/ERK signaling. Our study provides molecular insights into the tight regulation of EGFR/ERK signaling in niches for stem cell regenerative potential.

Cleavage of TL1A Differentially Regulates Its Effects on Innate and Adaptive Immune Cells.

TNF superfamily cytokines play major roles in the regulation of adaptive and innate immunity. The TNF superfamily cytokine TL1A (TNFSF15), through its cognate receptor DR3 (TNFRSF25), promotes T cell immunity to pathogens and directly costimulates group 2 and 3 innate lymphoid cells. Polymorphisms in the TNFSF15 gene are associated with the risk for various human diseases, including inflammatory bowel disease. Like other cytokines in the TNF superfamily, TL1A is synthesized as a type II transmembrane protein and cleaved from the plasma membrane by metalloproteinases. Membrane cleavage has been shown to alter or abrogate certain activities of other TNF family cytokines; however, the functional capabilities of membrane-bound and soluble forms TL1A are not known. Constitutive expression of TL1A in transgenic mice results in expansion of activated T cells and promotes intestinal hyperplasia and inflammation through stimulation of group 2 innate lymphoid cells. Through the generation of membrane-restricted TL1A-transgenic mice, we demonstrate that membrane TL1A promotes expression of inflammatory cytokines in the lung, dependent upon DR3 expression on T cells. Soluble TL1A alone was unable to produce this phenotype but was still able to induce intestinal type 2 inflammation independently of T cells. These data suggest differential roles for membrane and soluble TL1A on adaptive and innate immune cells and have implications for the consequences of blocking these two forms of TL1A.

DOP010 Activating PIK3CD mutations cause severe intestinal lymphonodular hyperplasia and an IBD-like phenotype

DOP010 Activating PIK3CD mutations cause severe intestinal lymphonodular hyperplasia and an IBD-like phenotype

Oncogenic BRAF mutation induces DNA methylation changes in a murine model for human serrated colorectal neoplasia

ABSTRACTColorectal cancer is a major cause of cancer death and approximately 20% arises within serrated polyps, which are under-recognized and poorly understood. Human serrated colorectal polyps frequently exhibit both oncogenic BRAF mutation and widespread DNA methylation changes, which are important in silencing genes restraining neoplastic progression. Here, we investigated whether in vivo induction of mutant Braf is sufficient to result in coordinated promoter methylation changes for multiple cancer-related genes. The BrafV637E mutation was induced in murine intestine on an FVB;C57BL/6J background and assessed for morphological and DNA methylation changes at multiple time points from 10 days to 14 months. Extensive intestinal hyperplasia developed by 10 days post-induction of the mutation. By 8 months, most mice had murine serrated adenomas with dysplasia and invasive cancer developed in 40% of mice by 14 months. From 5 months onwards, Braf mutant mice showed extensive, gene-specific increases in DNA methylation even in hyperplastic mucosa without lesions. This demonstrates that persistent oncogenic Braf signaling is sufficient to induce widespread DNA methylation changes. This occurs over an extended period of time, mimicking the long latency followed by rapid progression of human serrated neoplasia. This study establishes for the first time that DNA methylation arises slowly in direct response to prolonged oncogenic Braf signaling in serrated polyps; this finding has implications both for chemoprevention and for understanding the origin of DNA hypermethylation in cancer generally.

Prostaglandin D2 metabolite in urine is an index of food allergy

Food allergy is immediate hypersensitive reactions to ingested foods. Since early diagnosis is effective for disease control, development of an objective diagnostic index is required. Using mediator-lipidomics, we found that levels of the urinary prostaglandin D2 (PGD2) metabolite, tetranor-PGDM, reflected the severity of the allergic symptoms and intestinal mast cell hyperplasia in mice. Repeated oral challenges with ovalbumin promoted allergic symptoms in sensitized mice. Particularly, the allergic mice presented with increased numbers of intestinal mast cells, which strongly expressed hematopoietic PGD synthase (H-PGDS). The levels of urinary tetranor-PGDM increased as the disease progressed. Treatment with a mast cell inactivator or an anti-inflammatory steroid attenuated these symptoms and decreased the tetranor-PGDM urinary levels. The levels of urinary tetranor-PGDM did not correlate with the disease severity in murine models of colitis, asthma, or allergic dermatitis. Furthermore, we have shown that urinary levels of tetranor-PGDM were significantly higher in patients with food allergy than those in healthy volunteers and patients with other types of allergic diseases such as asthma, allergic rhinitis, and atopic dermatitis. These findings suggest that urinary tetranor-PGDM is a useful diagnostic index of food allergy in both mice and humans.

Regression of Low Grade Biliary Dysplasia Following Endoscopic Stent Placement: A Case Report

Choledochoduodenostomy (CDD) is a surgical technique in which the common bile duct (CBD) is anastomosed to the duodenum to create a fistulous tract. We report a case of biliary dysplasia which reversed, and then reoccurred with the placement of an endoscopic fully covered metal stent (FCMS) then its removal in a patient who underwent remote CDD. A 60-year-old woman with history of cholecystectomy and CDD performed in the 1970s for symptomatic episodes of retained biliary stones presented with recurrent epigastric pain and associated unintentional weight loss over a six month period. MRI of the abdomen showed intrahepatic biliary and common hepatic ductal dilation, a focal moderate grade stricture in the mid-portion of the CBD measuring 0.6 cm in length, and a fistulous tract extending posteriorly from the lower portion of the stricture connecting to the first portion of the duodenum. ERCP with cholangioscopy using Spyglass DS was performed and the mucosa of the bile duct was observed to have been replaced by brush border-like small bowel epithelium. Intestinal contents were seen refluxing into the bile duct through the fistulous tract. Biopsies of the stricture revealed intestinal metaplasia, gastric foveolar hyperplasia, and low grade dysplasia. A FCMS was placed to seal the fistulous tract. Subsequently, the patient reported resolution of her abdominal pain, increased tolerance of oral intake, and weight gain. Four months later, a second ERCP was performed, the FCMS was removed, and biopsies of the bile duct were obtained, with findings of resolution of dysplasia while intestinal metaplasia and gastric hyperplasia persisted. The patient underwent a stent-free trial. Two months later, the patient reported the recurrence of her index pain and food intolerance. Repeated ductal biopsies demonstrated recurrence of dysplasia. Again, a FCMS was placed with repeated symptomatic improvement. The patient was then referred to a surgeon for surgical correction. The mechanism for regression of biliary dysplasia following endoscopic stent placement is not well understood, but one explanation is that cholangiocytes normally remain in a persistent mitotically inactive state, but may proliferate depending on the nature of the stimulus. This case report shows that endoscopic FCMS placement may be useful in treatment of biliary dysplasia in patients with bilioenteric anastomosis or fistula.Figure: Top left - MRI of the abdomen demonstrating the bilioenteric fistula and stricture. Top right - Visualization of the biliary stricture on cholangioscopy. Bottom left - Small bowel-like epithelium in the biliary system seen on cholangioscopy.Figure: Slide 1 - tissue section from the bile duct, an area of fistula showing low grade dysplasia. Slide 2 - same tissue section as Slide 1 stained with P53 immunostain. The epithelial cells show increased P53 staining with features supporting low grade dysplasia (4X, P53 immunostain). Slide 3 - tissue section with goblet cell (arrow) indicating intestinal metaplasia of biliary epithelium (40X, H&E stain). Slide 4 - tissue section showing MUC2 staining of goblet cells in biliary epithelium supporting intestinal metaplasia (4X, MUC2 immunostain). Slide 5 - Alcian blue staining of goblet cells supporting intestinal metaplasia (40X, Alcian blue-PAS stain). Slide 6 - increased MUC5AC staining supporting gastric foveolar hyperplasia (4X, MUC5AC immunostain).

Basic Science Luminal

Basic Science Luminal

Abstract 5375: Oncogenic BRAF mutation induces widespread DNA hypermethylation in a murine model for human serrated colorectal neoplasia

Abstract BACKGROUND: The serrated colorectal neoplasia pathway describes the progression of morphologically serrated polyps to cancer and accounts for approximately one third of all colorectal cancer cases. Human serrated polyps are characterised by activating mutation of the BRAF oncogene and widespread DNA methylation changes termed the CpG Island Methylator Phenotype. A causative versus synergistic relationship between BRAF mutation and this methylator phenotype has not been determined. We aimed to address this by developing a murine model for serrated neoplasia driven by BRAF mutation. METHODS: BrafV637E conditionally active mice were crossed with intestine-specific, inducible Villin-CreERT2 mice to direct the BRAF mutation to the intestine at 2 weeks of age. The proximal ilieum or proximal colon were sampled at defined time points including 10 days, 10 weeks, 5 months, 8 months, 10 months, 12 months and 14 months. Macroscopic lesions larger than 10mm were bisected for molecular and histological assessment. The entire remaining intestine was fixed and examined histologically. DNA methylation was investigated for 94 genes known to by methylated in colorectal cancer using Epitect MethylII Complete PCR Arrays (Qiagen). RESULTS: Braf mutant mice displayed histologic changes analogous to the human serrated neoplasia pathway. Extensive intestinal hyperplasia developed by 10 days post induction of the BRAF mutation. By 10 weeks, 50% mice had developed areas of crypt dilation reminiscent of human sessile serrated adenomas. By 8 months, the majority of mice had murine serrated adenomas with dysplasia and invasive cancer developed in 40% of mice by 14 months, one of which metastasised to the liver. Compared to age-matched control mice, Braf mutant mice showed significant, gene-specific increases in DNA methylation from 5 months (p<0.0001). CONCLUSIONS: Using an in vivo model we observed the temporal accumulation of DNA methylation changes in hyperplastic epithelium in direct response to mutation of the BRAF oncogene. This murine model morphologically and molecularly recapitulates the human serrated neoplasia pathway and establishes a causative role for BRAF mutation in establishing a methylator phenotype. Note: This abstract was not presented at the meeting. Citation Format: Vicki Whitehall, Catherine Bond, Cheng Liu, Futoshi Kawamata, Diane McKeone, Saara Jamieson, Sally Pearson, Susan Woods, Tamsin Lannagan, Lochlan Fennell, Winnie Fernando, Mark Bettington, Daniel Worthley, Barbara Leggett. Oncogenic BRAF mutation induces widespread DNA hypermethylation in a murine model for human serrated colorectal neoplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5375. doi:10.1158/1538-7445.AM2017-5375

Abstract PR04: Wnt and MAPK pathway activation in conventional and serrated colorectal neoplasia

Abstract The WNT and MAPK signaling pathways are central to colorectal homeostasis. Mutation of the APC tumor suppressor gene activates the WNT pathway to initiate most conventional adenomas. By contrast, oncogenic BRAF mutation initiates development of sessile serrated adenomas (SSA) via activation of the MAPK pathway. The purpose of this study was to investigate the frequency, timing and mechanism of WNT pathway activation in serrated colorectal neoplasia. Methods: The WNT pathway was examined in a range of colorectal polyp and cancer subtypes. Aberrant nuclear immuno-localization of β-catenin was used as a surrogate for WNT pathway activation, compared to the normal membranous staining pattern. The entire coding region of the APC gene was sequenced using a custom enrichment panel that included 242 primer pairs (GeneRead DNAseq Targeted Panel, Qiagen) and the constructed library was sequenced using Illumina's HT TruSeq Kit. As another mechanism of activating WNT, mutations were also assessed in the E3 ubiquitin ligase genes RNF43 and ZNRF3 using Sanger sequencing. To test the interaction of the WNT and MAPK pathways in vivo, a conditional BRAF mutant mouse model was crossed with an inducible Cre driven by the murine Villin gene promoter, to restrict Cre expression and induction of the BRAF mutation to the intestine at 2 weeks. The chemical carcinogen azoxymethane was administered weekly for 6 weeks to activate the WNT pathway from 3 weeks of age. The potential therapeutic implication of targeting these pathways was tested in vitro using the porcupine inhibitor LGK974 and MEK inhibitor PD0325901. Results: The majority of conventional pathway polyps and cancers had nuclear localization of β-catenin (22/28, 79% adenomas and 36/42, 86% BRAF wildtype cancers) and mutations in APC (17/20, 85% adenomas and 19/30, 63% BRAF wild type cancers). Sessile serrated adenomas infrequently showed nuclear staining of β-catenin and 0/20 SSA had mutations. By contrast, the WNT signal was increased in the dysplastic component of SSA with a focus of dysplasia (76/137, 55%), however APC mutations were uncommon (3/20, 15%). Similarly, BRAF mutant cancers had nuclear β-catenin in 36/92 (39%) cancers compared to APC mutation in only 9/80 (11%) samples. This did not significantly differ when samples were stratified by microsatellite instability status. RNF43 and ZNRF3 were commonly mutated in BRAF mutant / microsatellite unstable cancers (47/54, 87% and 16/54, 30%, respectively) as well as BRAF mutant / microsatellite stable cancers (8/33, 24% and 5/33, 15%) compared to only 3/79 (4%) RNF43 mutations and 0/27 ZNRF3 mutations in BRAF wildtype cancers. This was accompanied by lower transcript expression for both RNF43 and ZNRF3 in BRAF mutant compared to BRAF wildtype cancers (P<0.0001). We further demonstrated the importance of the WNT pathway in progression of serrated neoplasia by administering azoxymethane to mice with BRAF mutant-induced intestinal hyperplasia. This accelerated the serrated phenotype from 0.6 polyps per mouse to 5.9 per mouse (P<0.001). These all showed typical murine serrated adenoma morphology. To investigate potential therapeutic implications we treated colorectal cancer cell lines with the porcupine inhibitor LGK974 and showed a 50% reduction in growth only in RNF43 and/or ZNRF3 mutant cell lines. In the BRAF / RNF43 / ZNRF3 mutant cell line RKO, LGK974 synergized with MEK inhibition to dramatically reduce growth by approximately 95%. Conclusions: The WNT pathway is commonly activated in serrated neoplasia at the transition to dysplasia. This is not due APC mutation but rather mutation of the upstream RNF43 and/or ZNRF43 genes or other WNT pathway targets. The combination of WNT and MAPK pathway inhibition offers potential for improving therapy for patients with serrated pathway cancers. This abstract is also being presented as Poster A21. Citation Format: Vicki Whitehall, Jennifer Borowsky, Catherine Bond, Mark Bettington, Sally-Ann Pearson, Murugan Kalimutho, John Liu, Troy Dumenil, Diane McKeone, Saara Jamieson, Winnie Fernando, Lochlan Fennell, Andrew Clouston, Christophe Rosty, Ian Brown, Neal Walker, Barbara Leggett. Wnt and MAPK pathway activation in conventional and serrated colorectal neoplasia. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr PR04.

Functional Effects of Prebiotic Fructans in Colon Cancer and Calcium Metabolism in Animal Models.

Inulin-type fructans are polymers of fructose molecules and are known for their capacity to enhance absorption of calcium and magnesium, to modulate gut microbiota and energy metabolism, and to improve glycemia. We evaluated and compared the effects of Chicory inulin “Synergy 1®” and inulin from Mexican agave “Metlin®” in two experimental models of colon cancer and bone calcium metabolism in mice and rats. Inulins inhibited the development of dextran sulfate sodium-induced colitis and colon cancer in mice; these fructans reduced the concentration of tumor necrosis factor alpha and prevented the formation of intestinal polyps, villous atrophy, and lymphoid hyperplasia. On the other hand, inulin treatments significantly increased bone densitometry (femur and vertebra) in ovariectomized rats without altering the concentration of many serum biochemical parameters and urinary parameters. Histopathology results were compared between different experimental groups. There were no apparent histological changes in rats treated with inulins and a mixture of inulins-isoflavones. Our results showed that inulin-type fructans have health-promoting properties related to enhanced calcium absorption, potential anticancer properties, and anti-inflammatory effects. The use of inulin as a prebiotic can improve health and prevent development of chronic diseases such as cancer and osteoporosis.

Nodular lymphoid hyperplasia: A thin grey zone between hyperplasia and Pathological aggregate

Introduction: The clinical-pathological characteristics of 12 patients with intestinal nodular lymphoid hyperplasia (NLH) are described with the aim to try and delineate between hyperplasia and pathological aggregate of lymphoid tissue in the intestine and its association with other diseases from Indian subcontinent. Materials and Method: 12 diagnosed cases of NLH were retrieved out of 2256 intestinal punch biopsy done at our centre and were evaluated as per histological criteria laid down by various authors including their clinical and pathological features. Results: Most frequent symptom includes diarrhoea and weight loss and the severity of these symptoms were directly proportional to the number and location of the lymphoid nodules. Prominent lymphoid nodules in mucosa and/or submucosa were documented histologically in all cases. One patient had associated common variable immunodeficiency which on follow up developed intestinal lymphoid malignancy of NHL type (DLBCL) and the other was having hypogammaglobulinemia. All cases showed absence of plasma cells, except one with predominant symptoms of Gastroesophageal reflux disease (GERD) rather than diarrhea. Conclusion: NLH runs as a benign course, but these cases should be followed up with histology as well as thorough clinical and biochemical evaluation to detect early lymphoma that can be managed efficiently.

The potential of blue lupins as a protein source, in the diets of laying hens

Layers diets typically contain 15–20% soya due to its high crude protein content (ca. 36%). Reliance on soya for protein can result in large increases in cost of feed due to the law of supply and demand as a global commodity. Lupin grains have high protein content (35–40%) but previous experience with white lupins has shown toxic effects in poultry due to high levels alkaloids and poor performance due to anti-nutritional Non-starch polysaccharides (NSP). Here blue lupins either processed or whole were trialled for their potential as a protein source. Point of lay chickens (64) at 16 weeks of age were weighed and allocated to 16 coops of four hens. Coops, as the experimental unit, were randomly allocated to four treatments: layers mash with soya (Control); or layers mash with 150g of lupin/kg diet with the lupin either: whole (Whole); dehulled (Dehulled) or dehulled + a solid state fermentation enzyme extract (SSF; 150g/tonne DM). All diets were ground and formulated to be balanced for energy, crude protein and essential amino acids using NIRS. No difference in growth rate, final hen weight, DM and water intake, eggs per day, mean egg weight, yellowness of yolk or chroma was found between treatments. There was a trend (P<0.1) for the SSF treatment to produce less heavy shells and a significant effect for the lupin treatments to have redder yolks (P<0.001). Fecal DM and bacterial counts were not different and there was no sign of enteritis or intestinal tissue hyperplasia from hen autopsies. Inclusion of blue lupins in the diet of laying hens at a rate of 150g/kg DM resulted in no adverse effects in production or hen health and could be used as part of a balanced ration with inclusion of NSP degrading enzymes to reduce reliance on soya protein.

LIN-23, an E3 Ubiquitin Ligase Component, Is Required for the Repression of CDC-25.2 Activity during Intestinal Development in Caenorhabditis elegans.

Caenorhabditis elegans (C. elegans) utilizes two different cell-cycle modes, binucleations during the L1 larval stage and endoreduplications at four larval moltings, for its postembryonic intestinal development. Previous genetic studies indicated that CDC-25.2 is specifically required for binucleations at the L1 larval stage and is repressed before endoreduplications. Furthermore, LIN-23, the C. elegans β-TrCP ortholog, appears to function as a repressor of CDC-25.2 to prevent excess intestinal divisions. We previously reported that intestinal hyperplasia in lin-23(e1883) mutants was effectively suppressed by the RNAi depletion of cdc-25.2. Nevertheless, LIN-23 targeting CDC-25.2 for ubiquitination as a component of E3 ubiquitin ligase has not yet been tested. In this study, LIN-23 is shown to be the major E3 ubiquitin ligase component, recognizing CDC-25.2 to repress their activities for proper transition of cell-cycle modes during the C. elegans postembryonic intestinal development. In addition, for the first time that LIN-23 physically interacts with both CDC-25.1 and CDC-25.2 and facilitates ubiquitination for timely regulation of their activities during the intestinal development.

Early Detection of T cell Transfer-induced Autoimmune Colitis by In Vivo Imaging System.

Inflammatory bowel disease is a chronic and progressive inflammatory intestinal disease that includes two major types, namely ulcerative colitis and Crohn’s disease (CD). CD is characterized by intestinal epithelial hyperplasia and inflammatory cell infiltration. Transfer of CD25−CD45RBhiCD4+ (naïve) T cells into immunodeficiency mice induces autoimmune colitis with pathological lesions similar to CD and loss of body weight 4 weeks after cell transfer. However, weight loss neither has sufficient sensitivity nor totally matches the pathological findings of CD. To establish an early and sensitive indicator of autoimmune colitis model, the transferred T cell-induced colitis mouse model was modified by transferring luciferase-expressing donor T cells and determining the colitis by in vivo imaging system (IVIS). Colitis was detected with IVIS 7–10 days before the onset of body weight loss and diarrhea. IVIS was also applied in the dexamethasone treatment trial, and was a more sensitive indicator than body weight changes. All IVIS signals were parallel to the pathological abnormalities of the gut and immunological analysis results. In summary, IVIS provides both sensitive and objective means to monitor the disease course of transferred T cell-induced CD and fulfills the 3Rs principle of humane care of laboratory animals.

Abstract 660: Modelling conventional and serrated colorectal tumorigenesis by altering the Wnt and MAPK signaling pathways

Abstract Background. The majority of conventional colorectal adenomas are initiated by activation of the Wnt signal, whilst activation of the MAPK pathway is associated with progression to cancer. In contrast, sessile serrated adenomas are initiated by activation of the MAPK signaling pathway due to mutation of the BRAF oncogene, whilst the Wnt pathway is activated at the transition to dysplasia. We hypothesised that whilst both the Wnt and MAPK pathways play key roles in colorectal tumorigenesis, the order in which these signaling pathways are activated would determine the morphology of the lesion arising. Methods. To test this hypothesis, we utilised a conditional BRAF mutant mouse model crossed with an inducible Cre driven by the murine Villin gene promoter, to restrict Cre expression and induction of the BRAF mutation to the intestine. The MAPK pathway was activated two weeks after birth, whilst activation of the Wnt signal was achieved using APCMin mice or the intestinal carcinogen azoxymethane. Morphology and number of lesions was confirmed by histologically examination. Nuclear β-catenin immunostaining provided a surrogate for activation of the Wnt signal. Results. Induction of the BRAF mutation resulted in the rapid and sustained development of widespread intestinal hyperplasia. Murine serrated adenomas (mSA) mimicking the morphology of human traditional serrated adenomas were observed by 5 months and by 10 months 8/18 (44.4%) mice had developed mSA, primarily in the duodenum. Activation of the Wnt pathway using azoxymethane dramatically accelerated the serrated phenotype in both the small intestine (2.9 mSA per mouse, P&amp;lt;0.01) and colon (3.1 mSA per mouse, P&amp;lt;0.05) by 3 months. The MAPK and Wnt pathways also synergized in APCMin mice, increasing the average number of conventional adenomas per mouse from 2.1 to 78.8 (P&amp;lt;0.001). Conclusion. The rapid induction of hyperplasia and exclusive development of serrated lesions demonstrates that BRAF mutation is a key molecular event underlying initiation of serrated neoplasia. Importantly, we have demonstrated that activation of the MAPK pathway through BRAF mutation is sufficient for commitment to the serrated pathway and that whilst subsequent activation of the Wnt signal can accelerate tumorigenesis, it is not sufficient to override the existing serrated morphology. Citation Format: Vicki Whitehall, Winnie Fernando, Diane McKeone, Mark Bettington, Sally Pearson, Catherine Bond, Barbara Leggett. Modelling conventional and serrated colorectal tumorigenesis by altering the Wnt and MAPK signaling pathways. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 660.

Malabsorption and intestinal adaptation after one anastomosis gastric bypass compared with Roux-en-Y gastric bypass in rats.

The technically easier one-anastomosis (mini) gastric bypass (MGB) is associated with similar metabolic improvements and weight loss as the Roux-en-Y gastric bypass (RYGB). However, MGB is controversial and suspected to result in greater malabsorption than RYGB. In this study, we compared macronutrient absorption and intestinal adaptation after MGB or RYGB in rats. Body weight and food intake were monitored and glucose tolerance tests were performed in rats subjected to MGB, RYGB, or sham surgery. Carbohydrate, protein, and lipid absorption was determined by fecal analyses. Intestinal remodeling was evaluated by histology and immunohistochemistry. Peptide and amino acid transporter mRNA levels were measured in the remodeled intestinal mucosa and those of anorexigenic and orexigenic peptides in the hypothalamus. The MGB and RYGB surgeries both resulted in a reduction of body weight and an improvement of glucose tolerance relative to sham rats. Hypothalamic orexigenic neuropeptide gene expression was higher in MGB rats than in RYGB or sham rats. Fecal losses of calories and proteins were greater after MGB than RYGB or sham surgery. Intestinal hyperplasia occurred after MGB and RYGB with increased jejunum diameter, higher villi, and deeper crypts than in sham rats. Peptidase and peptide or amino acid transporter genes were overexpressed in jejunal mucosa from MGB rats but not RYGB rats. In rats, MGB led to greater protein malabsorption and energy loss than RYGB. This malabsorption was not compensated by intestinal overgrowth and increased expression of peptide transporters in the jejunum.

Olfactomedin 4 expression and functions in innate immunity, inflammation, and cancer.

Olfactomedin 4 (OLFM4) is an olfactomedin domain-containing glycoprotein. Multiple signaling pathways and factors, including NF-κB, Wnt, Notch, PU.1, retinoic acids, estrogen receptor, and miR-486, regulate its expression. OLFM4 interacts with several other proteins, such as gene associated with retinoic-interferon-induced mortality 19 (GRIM-19), cadherins, lectins, nucleotide oligomerization domain-1 (NOD1) and nucleotide oligomerization domain-2 (NOD2), and cathepsins C and D, known to regulate important cellular functions. Recent investigations using Olfm4-deficient mouse models have provided important clues about its in vivo biological functions. Olfm4 inhibited Helicobacter pylori-induced NF-κB pathway activity and inflammation and facilitated H. pylori colonization in the mouse stomach. Olfm4-deficient mice exhibited enhanced immunity against Escherichia coli and Staphylococcus aureus infection. Olfm4 deletion in a chronic granulomatous disease mouse model rescued them from S. aureus infection. Olfm4 deletion in mice treated with azoxymethane/dextran sodium sulfate led to robust intestinal inflammation and intestinal crypt hyperplasia. Olfm4 deletion in Apc (Min/+) mice promoted intestinal polyp formation as well as adenocarcinoma development in the distal colon. Further, Olfm4-deficient mice spontaneously developed prostatic epithelial lesions as they age. OLFM4 expression is correlated with cancer differentiation, stage, metastasis, and prognosis in a variety of cancers, suggesting its potential clinical value as an early-stage cancer marker or a therapeutic target. Collectively, these data suggest that OLFM4 plays important roles in innate immunity against bacterial infection, gastrointestinal inflammation, and cancer. In this review, we have summarized OLFM4's initial characterization, expression, regulation, protein interactions, and biological functions.

H. pylori infection promotes intestinal inflammation and colitis-associated colon cancer in mice with a lineage-restricted deletion of the Smad4 gene in T cells.

Abstract Recent data suggest a protective effect of Helicobacter pylori (H. pylori) infection in inflammatory bowel disease (IBD), but the mechanisms mediating this protective effect are poorly understood. We previously reported that selective deletion in T cells of the TGF-β signaling intermediate in mice, Smad4 (Smad4TKO mice) leads to spontaneous gastrointestinal inflammation which progresses to mucosal epithelia cancers. Thus we infected Smad4TKO mice with H. pylori SS1 and PMSS1. Smad4TKO mice developed thickened intestinal mucosa, epithelial hyperplasia, crypt abscesses, and abundant inflammatory cell infiltrates between 2 and 3 months post infection. Some mice also developed colonic adenocarcinoma while wild type (WT) infected mice exhibited no gross or histologic signs of colitis. Smad4TKO mice infected with H. pylori had a increase in the number of mucosal effector CD4+ T cells producing IFN-g and IL-17 and a decrease in the mucosal Foxp3+CD4+ T cells (Tregs) in vivo, compared to WT mice infected with H. pylori. We also observed enhanced epithelia expressing PD-L1 in colon of Smad4TKO mice with H. pylori infection. The colon epithelia of Smad4TKO mice with H. pylori infection exhibited an oncogenic signature with an increase in the expression of iNOS and p-STAT1. Mutations in Smad4 are found in large percentage of human Juvenile Polyposis Syndrome (JPS) and Hereditary Hemorrhagic Telangiectasia (HTT) patients who are at risk of developing both adolescent and adult colon cancer. Our results raise the intriguing possibility that H. pylori infection could be a co-factor in the development of colon cancer by JPS/HTT patients.

IL-22 Restrains Tapeworm-Mediated Protection against Experimental Colitis via Regulation of IL-25 Expression.

Interleukin (IL)-22, an immune cell-derived cytokine whose receptor expression is restricted to non-immune cells (e.g. epithelial cells), can be anti-inflammatory and pro-inflammatory. Mice infected with the tapeworm Hymenolepis diminuta are protected from dinitrobenzene sulphonic acid (DNBS)-induced colitis. Here we assessed expulsion of H. diminuta, the concomitant immune response and the outcome of DNBS-induced colitis in wild-type (WT) and IL-22 deficient mice (IL-22-/-) ± infection. Interleukin-22-/- mice had a mildly impaired ability to expel the worm and this correlated with reduced or delayed induction of TH2 immunity as measured by splenic and mesenteric lymph node production of IL-4, IL-5 and IL-13 and intestinal Muc-2 mRNA and goblet cell hyperplasia; in contrast, IL-25 increased in the small intestine of IL-22-/- mice 8 and 12 days post-infection compared to WT mice. In vitro experiments revealed that H. diminuta directly evoked epithelial production of IL-25 that was inhibited by recombinant IL-22. Also, IL-10 and markers of regulatory T cells were increased in IL-22-/- mice that displayed less DNBS (3 mg, ir. 72h)-induced colitis. Wild-type mice infected with H. diminuta were protected from colitis, as were infected IL-22-/- mice and the latter to a degree that they were almost indistinguishable from control, non-DNBS treated mice. Finally, treatment with anti-IL-25 antibodies exaggerated DNBS-induced colitis in IL-22-/- mice and blocked the anti-colitic effect of infection with H. diminuta. Thus, IL-22 is identified as an endogenous brake on helminth-elicited TH2 immunity, reducing the efficacy of expulsion of H. diminuta and limiting the effectiveness of the anti-colitic events mobilized following infection with H. diminuta in a non-permissive host.

Type I Interferons Control Proliferation and Function of the Intestinal Epithelium.

Wnt pathway-driven proliferation and renewal of the intestinal epithelium must be tightly controlled to prevent development of cancer and barrier dysfunction. Although type I interferons (IFN) produced in the gut under the influence of microbiota are known for their antiproliferative effects, the role of these cytokines in regulating intestinal epithelial cell renewal is largely unknown. Here we report a novel role for IFN in the context of intestinal knockout of casein kinase 1α (CK1α), which controls the ubiquitination and degradation of both β-catenin and the IFNAR1 chain of the IFN receptor. Ablation of CK1α leads to the activation of both β-catenin and IFN pathways and prevents the unlimited proliferation of intestinal epithelial cells despite constitutive β-catenin activity. IFN signaling contributes to the activation of the p53 pathway and the appearance of apoptotic and senescence markers in the CK1α-deficient gut. Concurrent genetic ablation of CK1α and IFNAR1 leads to intestinal hyperplasia, robust attenuation of apoptosis, and rapid and lethal loss of barrier function. These data indicate that IFN play an important role in controlling the proliferation and function of the intestinal epithelium in the context of β-catenin activation.