A simple, practical 'swiss roll' method of preparing tissues for paraffin or methacrylate embedding

N6-adenomethylation of GsdmC is essential for Lgr5+ stem cell survival to maintain normal colonic epithelial morphogenesis

Gut epithelial morphogenesis is maintained by intestinal stem cells. Here, we report that depletion of N6-adenosine methyltransferase subunit Mettl14 from gut epithelial cells in mice impaired colon mucosal morphogenesis, leading to increased mucosal permeability, severe inflammation, growth retardation, and premature death. Mettl14 ablation triggered apoptosis that depleted Lgr5+ stem cells and disrupted colonic organoid growth and differentiation, whereas the inhibition of apoptosis rescued Mettl14-deleted mice and organoids. Mettl14 depletion disrupted N6-adenomethylation on GsdmC transcripts and abolished GsdmC expression. Reconstitution of Mettl14-deleted organoids or mice with GSDMC rescued Lgr5 expression and prevented apoptosis and mouse premature death, whereas GSDMC silence eliminated LGR5 and triggered apoptosis in human colonic organoids and epithelial cells. Mechanistically, Mettl14 depletion eliminated mitochondrial GsdmC, disrupted mitochondrial membrane potential, and triggered cytochrome c release that activates the pro-apoptotic pathway. In conclusion, GsdmC N6-adenomethylation protects mitochondrial homeostasis and is essential for Lgr5+ cell survival to maintain normal colonic epithelial regeneration.

Short-Term High-Fat Diet Fuels Colitis Progression in Mice Associated With Changes in Blood Metabolome and Intestinal Gene Expression

Clinical cases and animal experiments show that high-fat (HF) diet is involved in inflammatory bowel disease (IBD), but the specific mechanism is not fully clear. A close association between long-term HF-induced obesity and IBD has been well-documented. However, there has been limited evaluation of the impact of short-term HF feeding on the risk of intestinal inflammation, particularly on the risk of disrupted metabolic homeostasis. In this study, we analyzed the metabolic profile and tested the vulnerability of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis after short-term HF feeding in mice. The results showed that compared with the control diet (CD), the fatty acid (FA), amino acid (AA), and bile acid (BA) metabolisms of mice in the HF group were significantly changed. HF-fed mice showed an increase in the content of saturated and unsaturated FAs and a decrease in the content of tryptophan (Trp). Furthermore, the disturbed spatial distribution of taurocholic acid (TCA) in the ileum and colon was identified in the HF group using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI). After HF priming, mice on TNBS induction were subjected to more severe colonic ulceration and histological damage compared with their CD counterparts. In addition, TNBS enema induced higher gene expressions of mucosal pro-inflammatory cytokines under HF priming conditions. Overall, our results show that HF may promote colitis by disturbing lipid, AA, and BA metabolic homeostasis and inflammatory gene expressions.

Identification and Spatial Visualization of Dysregulated Bile Acid Metabolism in High-Fat Diet-Fed Mice by Mass Spectral Imaging

Changes in overall bile acid (BA) levels and specific BA metabolites are involved in metabolic diseases, gastrointestinal, and liver cancer. BAs have become established as important signaling molecules that enable fine-tuned inter-tissue communication within the enterohepatic circulation. The liver, BAs site of production, displayed physiological and functional zonal differences in the periportal zone versus the centrilobular zone. In addition, BA metabolism shows regional differences in the intestinal tract. However, there is no available method to detect the spatial distribution and molecular profiling of BAs within the enterohepatic circulation. Herein, we demonstrated the application in mass spectrometry imaging (MSI) with a high spatial resolution (3 μm) plus mass accuracy matrix-assisted laser desorption ionization (MALDI) to imaging BAs and N-1-naphthylphthalamic acid (NPA). Our results could clearly determine the zonation patterns and regional difference characteristics of BAs on mouse liver, ileum, and colon tissue sections, and the relative content of BAs based on NPA could also be ascertained. In conclusion, our method promoted the accessibility of spatial localization and quantitative study of BAs on gastrointestinal tissue sections and demonstrated that MALDI-MSI was a valuable tool to investigate and locate several BA molecules in different tissue types leading to a better understanding of the role of BAs behind the gastrointestinal diseases.

Transition state analogue of MTAP extends lifespan of APCMin/+ mice

A mouse model of human Familial Adenomatous Polyposis responds favorably to pharmacological inhibition of 5'-methylthioadenosine phosphorylase (MTAP). Methylthio-DADMe-Immucillin-A (MTDIA) is an orally available, transition state analogue inhibitor of MTAP. 5'-Methylthioadenosine (MTA), the substrate for MTAP, is formed in polyamine synthesis and is recycled by MTAP to S-adenosyl-L-methionine (SAM) via salvage pathways. MTDIA treatment causes accumulation of MTA, which inhibits growth of human head and neck (FaDu) and lung (H359, A549) cancers in immunocompromised mouse models. We investigated the efficacy of oral MTDIA as an anti-cancer therapeutic for intestinal adenomas in immunocompetent APCMin/+ mice, a murine model of human Familial Adenomatous Polyposis. Tumors in APCMin/+ mice were decreased in size by MTDIA treatment, resulting in markedly improved anemia and doubling of mouse lifespan. Metabolomic analysis of treated mice showed no changes in polyamine, methionine, SAM or ATP levels when compared with control mice but indicated an increase in MTA, the MTAP substrate. Generation of an MTDIA-resistant cell line in culture showed a four-fold amplification of the methionine adenosyl transferase (MAT2A) locus and expression of this enzyme. MAT2A is downstream of MTAP action and catalyzes synthesis of the SAM necessary for methylation reactions. Immunohistochemical analysis of treated mouse intestinal tissue demonstrated a decrease in symmetric dimethylarginine, a PRMT5-catalyzed modification. The anti-cancer effects of MTDIA indicate that increased cellular MTA inhibits PRMT5-mediated methylations resulting in attenuated tumor growth. Oral dosing of MTDIA as monotherapy has potential for delaying the onset and progression of colorectal cancers in Familial Adenomatous Polyposis (FAP) as well as residual duodenal tumors in FAP patients following colectomy. MTDIA causes a physiologic inactivation of MTAP and may also have efficacy in combination with inhibitors of MAT2A or PRMT5, known synthetic-lethal interactions in MTAP-/- cancer cell lines.

Ciprofloxacin self-dissolvable Soluplus based polymeric films: a novel proposal to improve the management of eye infections

Infections of the eye are among the leading causes of vision impairment and vision loss worldwide. The ability of a drug to access the anterior parts of the eye is negligible after systemic administration. Effective drug delivery to the eye is a major challenge due to the presence of protective mechanisms and physiological barriers that result in low ocular availability after topical application. The main purpose of this work was the improvement of the corneal and conjunctival permeation of the antibiotic Ciprofloxacin, a wide spectrum antibiotic used for the most common eye infection, using a self-dissolving polymeric film. Films were prepared by the solvent casting technique, using polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft co-polymer (Soluplus), polyvynyl alcohol, and propylene glycol. Films were homogeneous in drug content and thickness, as demonstrated by adapting the Swiss Roll technique followed by microscopy observation. These films proved in vitro to control the release of the Ciprofloxacin. Ex vivo permeability studies using Franz diffusion cells and porcine cornea and sclera showed an effective permeability of the drug without inducing irritation of the tissues. Films swelled in contact with artificial tears forming an in situ gel over 20 min, which will improve drug contact and reduce the need of multiple dosing. The antibiotic activity was also tested in vitro in five types of bacterial cultures, assuring the pharmacological efficacy of the films. The developed films are a promising drug delivery system to topically treat or prevent ocular infections.

Recent advances in the pathology of heritable gastric cancer syndromes

Despite the relative rarity of hereditary gastric cancer syndromes, the prompt recognition of their specific clinical features and histopathological characteristics is pivotal in offering patients the most appropriate treatment. In this article, we address the three major inherited syndromes that primarily affect the stomach: hereditary diffuse gastric cancer (HDGC), caused by germline variants in CDH1 and CTNNA1; gastric adenocarcinoma and proximal polyposis of the stomach, caused by germline mutations in promoter 1B of APC; and familial intestinal gastric cancer, which has a poorly defined genetic cause. The main focus will be on HDGC, in light of the recent publication of updated clinical practice guidelines and emerging concepts regarding HDGC histopathology. In particular, we describe the broad morphological spectrum of HDGC lesions, stressing the importance of recognising indolent and aggressive phenotypes. Moreover, we discuss the increased risk of gastric (pre)malignancies developing in patients with other well-defined hereditary cancer syndromes, such as familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, juvenile polyposis, Li-Fraumeni syndrome, and hereditary breast and ovarian cancer syndrome.

Gastroscopic surveillance with targeted biopsies compared with random biopsies in CDH1 mutation carriers

BACKGROUND : The International Gastric Cancer Linkage Consortium (IGCLC) consensus guideline advises prophylactic gastrectomy in early adulthood to prevent gastric cancer development in CDH1 germline mutation carriers; psychosocial reasons may postpone gastrectomy. We analyzed the yield of signet-ring cell carcinoma (SRCC) during surveillance gastroscopy in CDH1 mutation carriers. METHODS : A retrospective analysis on surveillance gastroscopies in CDH1 mutation carriers was performed. The yield of SRCC in both targeted and random biopsies was studied. Endoscopic (biopsy) results were compared with the histopathologic outcomes in gastrectomy specimens. RESULTS : 42 CDH1 mutation carriers (18 men; mean age 43, range 20-82 years) underwent 96 surveillance gastroscopies. SRCC lesions were identified on surveillance gastroscopy in 21 patients (50 %), by either targeted biopsies only (n = 11), random biopsies only (n = 3), or both random and targeted biopsies (n = 7). SRCC was detected in 41 /377 targeted biopsies (11 %), whereas random biopsies revealed SRCC in 14/1563 biopsies (0.9 %). At least one SRCC lesion was found in 26 of 30 gastrectomy specimens. In 18 of these 26 specimens (69 %), SRCC had been identified by endoscopic biopsies. Missed lesions were all small superficial SRCC foci, mainly in the body of the stomach. CONCLUSION : In our cohort of CDH1 mutation carriers, SRCC lesions were identified by an extensive endoscopic surveillance protocol in 69 % of SRCC-positive patients who underwent a gastric resection. The low number of SRCC detected through random sampling demands a critical reappraisal of random biopsy sampling in the IGCLC guideline.

Chronic in vivo exposure to Helicobacter pylori VacA: Assessing the efficacy of automated and long-term intragastric toxin infusion

Helicobacter pylori (Hp) secrete VacA, a diffusible pore-forming exotoxin that is epidemiologically linked to gastric disease in humans. In vitro studies indicate that VacA modulates gastric epithelial and immune cells, but the in vivo contributions of VacA as an important determinant of Hp colonization and chronic infection remain poorly understood. To identify perturbations in the stomachs of C57BL/6 or BALB/C mice that result specifically from extended VacA exposure, we evaluated the efficacy of administering purified toxin using automated infusion via surgically-implanted, intragastric catheters. At 3 and 30 days of interrupted infusion, VacA was detected in association with gastric glands. In contrast to previously-reported tissue damage resulting from short term exposure to Hp extracts administered by oral gavage, extended infusion of VacA did not damage stomach, esophageal, intestinal, or liver tissue. However, several alterations previously reported during Hp infection were detected in animals infused with VacA, including reduction of the gastric mucus layer, and increased vacuolation of parietal cells. VacA infusion invoked an immune response, as indicated by the detection of circulating VacA antibodies. These foundational studies support the use of VacA infusion for identifying gastric alterations that are unambiguously attributable to long-term exposure to toxin.

Developmental 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure of either parent enhances the risk of necrotizing enterocolitis in neonatal mice

BACKGROUND

Necrotizing enterocolitis (NEC) is a rare, but potentially fatal intestinal inflammatory condition most often arising in premature infants. Infants provided formula are also at greater risk of developing this disease. Although the majority of formula-fed, preterm infants do not develop NEC, up to 30% of infants with the disease do not survive. Thus, identifying additional, currently unrecognized factors, which may predispose a specific infant to NEC development would be a significant clinical advancement. In this regard, we have previously reported that offspring of female or male mice with a history of developmental exposure to the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibit altered sensitivity to inflammatory challenges and are frequently born premature. Herein, we examined the possibility that, compared to unexposed mice (F1_NONE ), developmental TCDD exposure of either parent (maternal, F1M_TCDD , or paternal, F1P_TCDD ) would enhance the risk of NEC in offspring (F2_TCDD mice) in association with supplemental formula feeding.

METHODS

Beginning on postnatal day 7, all neonates were randomized to maternal milk only or maternal milk with up to 20 supplemental formula feedings. All pups remained with the Dams and were additionally allowed to nurse ad libitum.

RESULTS

Formula-fed F2_NONE pups rarely developed NEC while this disease was common in formula-fed F2M_TCDD and F2P_TCDD mice. Unexpectedly, 50% of F2M_TCDD pups that were not provided supplemental formula also developed NEC.

CONCLUSIONS

Our studies provide evidence that a history of parental TCDD exposure enhances the risk of NEC in offspring and suggest exposure to environmental immunotoxicants such as TCDD may also contribute to this inflammatory disease in humans.

High-fat diet promotes experimental colitis by inducing oxidative stress in the colon

Diets high in animal fats are associated with increased risks of inflammatory bowel disease, but the mechanism remains unclear. In this study, we investigated the effect of high-fat diet (HFD) on the development of experimental colitis in mice. Relative to mice fed low-fat diet (LFD), HFD feeding for 4 wk increased the levels of triglyceride, cholesterol, and free fatty acids in the plasma as well as within the colonic mucosa. In an experimental colitis model induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS), mice on 4-wk HFD exhibited more severe colonic inflammation and developed more severe colitis compared with the LFD counterparts. HFD feeding resulted in higher production of mucosal pro-inflammatory cytokines, greater activation of the myosin light chain kinase (MLCK) tight junction regulatory pathway, and greater increases in mucosal barrier permeability in mice following TNBS induction. HFD feeding also induced gp91, an NADPH oxidase subunit, and promoted reactive oxygen species (ROS) production in both colonic epithelial cells and lamina propria cells. In HCT116 cell culture, palmitic acid or palmitic acid and TNF-α combination markedly increased ROS production and induced the MLCK pathway, and these effects were markedly diminished in the presence of a ROS scavenger. Taken together, these data suggest that HFD promotes colitis by aggravating mucosal oxidative stress, which rapidly drives mucosal inflammation and increases intestinal mucosal barrier permeability.NEW & NOTEWORTHY This study demonstrates high-fat diet feeding promotes colitis in a 2,4,6-trinitrobenzenesulfonic acid-induced experimental colitis model in mice. The underlying mechanism is that high-fat diet induces oxidative stress in the colonic mucosa, which increases colonic epithelial barrier permeability and drives colonic mucosal inflammation. These observations provide molecular evidence that diets high in saturated fats are detrimental to patients with inflammatory bowel diseases.

Comparison of two techniques for a comprehensive gut histopathological analysis: Swiss Roll versus Intestine Strips

Assessing the gut mucosa milieu is important to grade the inflammatory process in conditions such as food hypersensitivity, allergy, gut parasitosis, etc. However, the gastrointestinal tract comprises a challenging system to evaluate, due to its thin tubular structure and mucosa, which suffer fast autolysis after death. Irrespective of the preferred inflammatory score system, it is important to choose the technique that will render the best tissue analysis. Thus, our aim was to compare two of the most frequently used methods to collect, process and analyze gut segments, the Swiss Roll and the Intestinal Strips. Normal C57Bl/6 mice were randomly assigned to Rolls or Strips group. After an overdose of anesthetics, segments of the duodenum, jejunum and ileum were collected and prepared accordingly for histological processing and analysis. Our results show the villi in the Rolls tend to be shorter and wider than those in the Strips in the duodenum and jejunum but not the ileum. No significant differences were observed in intra-epithelial lymphocytes and goblet cells counts. Finally, we staged each segment using our histomorphometric classification system, which revealed that although all animals presented a normal intestinal mucosa, those assigned to the Rolls group had their mucosa staged in the Infiltrative Stage while the Strips group had their mucosa staged as Normal. In conclusion, Swiss Rolls might be desirable for a wider assessment of the intestine, as it allows large segments to be analyzed at once, while Strips are better suited when detailed evaluation of each villus is intended.

Renin-angiotensin system promotes colonic inflammation by inducing TH17 activation via JAK2/STAT pathway

Previous studies suggest that the renin-angiotensin system (RAS) is a pathogenic factor for colitis. The goal of this study was to elucidate the molecular mechanism whereby angiotensin II (ANG II) promotes colonic inflammation. We found that renin was highly induced in colonic biopsies from patients with ulcerative colitis or Crohn's disease, and colonic renin and ANG II levels were markedly increased in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model, indicating that the colonic RAS is activated in colitis. Renin transgenic (RenTg) mice exhibited increased phosphorylation in Janus kinase-2 (JAK2) and signal transducer and activator of transcription1/3 (STAT1/3) within colonic mucosa at baseline and following TNBS induction, suggesting that ANG II promotes colonic inflammation via the JAK2/STAT1/3 pathway. Treatment with pan-JAK inhibitor tofacitinib blocked JAK2 and STAT1/3 phosphorylation, attenuated T helper (T_H)1 and T_H17 responses, alleviated colitis, and prevented death of RenTg mice in TNBS model. ANG II stimulated JAK2/STAT1/3 phosphorylation in both Jurkat T lymphocytes and HCT116 epithelial cells. In vitro polarization assays demonstrated that ANG II directly promoted T_H17 polarization, but not T_H1 polarization, via JAK2/STAT1/3. ANG II stimulation of transforming growth factor-β1 (TGFβ1), IL-6, myosin light chain kinase, and p53 upregulated modulator of apoptosis in HCT116 cells was also mediated by JAK2/STAT1/3. These observations suggest that ANG II promotes T_H17 polarization directly as well as indirectly by inducing production of T_H17-polarizing cytokines (e.g., TGFβ1 and IL-6) from colonic epithelial cells, both via the JAK2/STAT pathway. Therefore, colonic RAS promotes colonic inflammation, at least in part, by stimulating T_H17 activation. NEW & NOTEWORTHY This study demonstrates that the local renin-angiotensin system in the colon is activated in colitis development, which promotes mucosal T helper cell activation through the JAK2/STAT pathway. These observations provide molecular evidence that the renin-angiotensin system is a pathogenic factor for the development of inflammatory bowel diseases.

Outcomes after prophylactic gastrectomy for hereditary diffuse gastric cancer

BACKGROUND

Patients with hereditary diffuse gastric cancer and a CDH1 mutation have a 60-80 per cent lifetime risk of developing diffuse gastric cancer. Total prophylactic gastrectomy eliminates this risk, but is associated with considerable morbidity. The effectiveness (removal of all gastric mucosa) and outcomes of this procedure were evaluated retrospectively.

METHODS

All consecutive individuals undergoing a prophylactic gastrectomy for a CDH1 mutation or gastric signet ring cell foci at the authors' institute between 2005 and 2017 were included.

RESULTS

In 25 of 26 patients, intraoperative frozen-section examination (proximal resection margin) was used to verify complete removal of gastric mucosa. All definitive resection margins were free of gastric mucosa, but only after the proximal margin had been reresected in nine patients. In the first year after surgery, five of the 26 patients underwent a relaparotomy for adhesiolysis (2 patients) or jejunostomy-related complications (3 patients). Six patients were readmitted to the hospital within 1 year for nutritional and/or psychosocial support (4 patients) or surgical reintervention (2 patients). Mean weight loss after 1 year was 15 (95 per cent c.i. 12 to 18) per cent. For the 25 patients with a follow-up at 1 year or more, functional complaints were reported more frequently at 1 year than at 3 months after the operation: bile reflux (15 versus 11 patients respectively) and dumping (11 versus 7 patients). The majority of patients who worked or studied before surgery (15 of 19) had returned fully to these activities within 1 year.

CONCLUSION

The considerable morbidity and functional consequences of gastrectomy should be considered when counselling individuals with an inherited predisposition to diffuse gastric cancer. Intraoperative frozen-section examination is recommended to remove all risk-bearing gastric mucosa.

Marine microalgae bioengineered Schizochytrium sp. meal hydrolysates inhibits acute inflammation

Bioengineered marine microalgae Schizochytrium sp. is currently used to produce docosahexaenoic acid (DHA). However, following DHA extraction, the remaining protein-rich materials are not well utilized. In this study, we report that marine microalgae bioengineered Schizochytrium sp. hydrolysate (MESH), which exhibits a unique peptide profile as identified by Ultra Performance Liquid Chromatography coupled with Q-TOF mass spectrometry(UPLC/Q-TOF-MS), ameliorated bowel inflammation in mice. In a mouse model of experimentalcolitis induced by dextran sulfate sodium, compared with the control mice, the mice treated with MESH were highly resistant to colitis, as demonstrated by marked reductions in body weight loss, clinical colitis scores, colonic histological damage, and colonic inflammation. Mechanistically, MESH attenuated the induction of pro-inflammatory cytokines and increased the induction of anti-inflammatory cytokines. MESH also promoted the proliferation of colonic crypt stem cells and progenitor cells required for crypt repair. Collectively, these results reveal a previously unrecognized role of MESH as a potential anti-inflammatory treatment for colitis.

Therapeutic effect of the natural compounds baicalein and baicalin on autoimmune diseases

A series of natural compounds have been implicated to be useful in regulating the pathogenesis of various autoimmune diseases. The present study demonstrated that the Scutellariae radix compounds baicalein and baicalin may serve as drugs for the treatment of autoimmune diseases, including rheumatoid arthritis and inflammatory bowel disease. Following the administration of baicalein and baicalin in vivo, T cell‑mediated autoimmune diseases in the mouse model were profoundly ameliorated: In the collagen‑induced arthritis model (CIA), the severity of the disease was reduced by baicalein and, consistently, baicalein was demonstrated to suppress T cell proliferation in CIA mice. In the dextran sodium sulfate (DSS)‑induced colitis model, the disease was attenuated by baicalin, and baicalin promoted colon epithelial cell (CEC) proliferation in vitro. The present study further revealed that the mRNA expression of signal transducer and activator of transcription (STAT)3 and STAT4 in the tyrosine‑protein kinase JAK‑STAT signaling pathway in T cells was downregulated by baicalein, contributing to its regulation of T cell proliferation. However, in the DSS model, the STAT4 transcription in CECs, which are the target cells of activated T cells in the gut, was downregulated by baicalin, suggesting that baicalein and baicalin mediated similar STAT expression in different cell types in autoimmune diseases. In conclusion, the similarly structured compounds baicalein and baicalin selectively exhibited therapeutic effects on autoimmune diseases by regulating cell proliferation and STAT gene expression, albeit in different cell types.

Microbiota-Dependent Induction of Colonic Cyp27b1 Is Associated With Colonic Inflammation: Implications of Locally Produced 1,25-Dihydroxyvitamin D3 in Inflammatory Regulation in the Colon

Our recent studies demonstrated that intestinal epithelial vitamin D receptor (VDR) signaling plays a critical role in regulating colonic inflammation by protecting epithelial barrier integrity. Epithelial VDR is downregulated in colitis, but how mucosal inflammation affects local 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] production is unknown. Here we showed that cytochrome P450 27b1 (Cyp27b1), a cytochrome P450 enzyme necessary for 1,25(OH)2D3 biosynthesis, is highly induced in colonic mucosa in inflammatory response. Although VDR is reduced in colon biopsies from patients with ulcerative colitis, Cyp27b1 is markedly upregulated in these samples. Colon mucosal Cyp27b1 was also markedly induced in an experimental colitis mouse model, and this local Cyp27b1 induction and colonic inflammation required the presence of commensal bacteria. Vitamin D deficiency further exaggerated colonic Cyp27b1 induction and aggravated colonic inflammation in mice. In HCT116 cells, lipopolysaccharide or tumor necrosis factor-α treatment induced Cyp27b1 in time- and dose-dependent manners, and the induced Cyp27b1 was enzymatically active. The inflammation-induced upregulation of Cyp27b1 was mediated by nuclear factor κB. Collectively these data suggest that induction of colonic epithelial Cyp27b1, which is expected to increase local production of 1,25(OH)2D3, is a protective mechanism that partially compensates for the downregulation of epithelial VDR during colonic inflammation. Increased local 1,25(OH)2D3 maintains 1,25(OH)2D3-VDR signaling to protect the mucosal barrier and reduce colonic inflammation.

Analyzing Beneficial Effects of Nutritional Supplements on Intestinal Epithelial Barrier Functions During Experimental Colitis

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic relapsing disorders of the intestines. They cause severe problems, such as abdominal cramping, bloody diarrhea, and weight loss, in affected individuals. Unfortunately, there is no cure yet, and treatments only aim to alleviate symptoms. Current treatments include anti-inflammatory and immunosuppressive drugs that may cause severe side effects. This warrants the search for alternative treatment options, such as nutritional supplements, that do not cause side effects. Before their application in clinical studies, such compounds must be rigorously tested for effectiveness and security in animal models. A reliable experimental model is the dextran sulfate sodium (DSS) colitis model in mice, which reproduces many of the clinical signs of ulcerative colitis in humans. We recently applied this model to test the beneficial effects of a nutritional supplement containing vitamins C and E, L-arginine, and ω3-polyunsaturated fatty acids (PUFA). We analyzed various disease parameters and found that this supplement was able to ameliorate edema formation, tissue damage, leukocyte infiltration, oxidative stress, and the production of pro-inflammatory cytokines, leading to an overall improvement in the disease activity index. In this article, we explain in detail the correct application of nutritional supplements using the DSS colitis model in C57Bl/6 mice, as well as how disease parameters such as histology, oxidative stress, and inflammation are assessed. Analyzing the beneficial effects of different diet supplements may then eventually open new avenues for the development of alternative treatment strategies that alleviate IBD symptoms and/or that prolong the phases of remission without causing severe side effects.

Antibody-Based Targeted Delivery of Interleukin-22 Promotes Rapid Clinical Recovery in Mice With DSS-Induced Colitis

BACKGROUND

We have recently described the potential of the alternatively spliced extradomain A of fibronectin as a target for antibody-based pharmacodelivery applications in ulcerative colitis. Here, we report on the cloning and therapeutic properties of novel antibody-based fusion proteins, comprising the F8 antibody specific to extradomain A and murine interleukin (IL)-22, a globular cytokine belonging to the IL10 family. A protective function for IL22 in colitis has previously been described, as this cytokine induces antimicrobial, proliferative, and antiapoptotic pathways, preventing tissue damage and promoting epithelial repair.

METHODS

Two fusion proteins comprising IL22, fused at the N- or at the C-terminus of the F8 antibody in diabody format, were expressed in mammalian cells. The ability of radiolabeled preparations of the 2 fusion proteins to localize at sites of disease was assessed by autoradiography in a murine model of dextran sodium sulfate-induced colitis and by quantitative biodistribution analysis in a syngeneic mouse teratocarcinoma model. Therapeutic activity was assessed in mice with dextran sodium sulfate-induced colitis, which received intravenous injections of antibody-cytokine fusion proteins.

RESULTS

Both fusion proteins were able to selectively accumulate at the site of disease. The fusion protein with the cytokine moiety at the N-terminal extremity (IL22-F8) exhibited better results than the C-terminal fusion, both in terms of targeting selectivity and therapeutic efficacy. Mice treated with IL22-F8 showed a more rapid recovery from clinical symptoms compared with controls and improved macroscopic and microscopic morphology of the colon.

CONCLUSIONS

IL22-F8 is a promising biopharmaceutical drug candidate for the treatment of ulcerative colitis.

Improved Swiss-rolling Technique for Intestinal Tissue Preparation for Immunohistochemical and Immunofluorescent Analyses

Understanding the role of factors that regulate intestinal epithelial homeostasis and response to injury and regeneration is important. The current literature describes several different methodological approaches to obtain images of intestinal tissues for data validation. In this paper, we delineate a common protocol relating to the derivation and processing of mouse intestinal tissues. Proper fixation of intestinal tissues and Swiss-roll techniques that enhance intestinal epithelial morphology are discussed. Postresection processing and reorientation of embedded intestinal tissues are critical in obtaining paraffin-embedded blocks that display intact intestinal structural features after sectioning. The Swiss-rolling technique helps in histological assessment of the complete intestinal or colonic sections examined. An ability to differentiate intestinal structural features can be vital in quantitative measurements of intestinal inflammation and tumorigenesis along the entire length. Finally, paraffin-embedded sections are ideal for robust processing using both immunohistochemical and immunofluorescent detection methods. Nonfluorescent immunohistochemical sections provide a vibrant image of the tissue detailing different cellular structural features but do not provide flexibility for intracellular co-localization experiments. Multiple fluorescent channels can be appropriately utilized with immunofluorescent detection for co-localization experiments, lending support to mechanistic studies.

Activation of the Renin-Angiotensin System Promotes Colitis Development

The renin-angiotensin system (RAS) plays pathogenic roles in renal and cardiovascular disorders, but whether it is involved in colitis is unclear. Here we show that RenTgMK mice that overexpress active renin from the liver developed more severe colitis than wild-type controls. More than 50% RenTgMK mice died whereas all wild-type mice recovered. RenTgMK mice exhibited more robust mucosal T_H17 and T_H1/T_H17 responses and more profound colonic epithelial cell apoptosis compared to wild-type controls. Treatment with aliskiren (a renin inhibitor), but not hydralazine (a smooth muscle relaxant), ameliorated colitis in RenTgMK mice, although both drugs normalized blood pressure. Chronic infusion of angiotensin II into wild-type mice mimicked the severe colitic phenotype of RenTgMK mice, and treatment with losartan [an angiotensin type 1 receptor blocker (ARB)] ameliorated colitis in wild-type mice, confirming a colitogenic role for the endogenous RAS. In human biopsies, pro-inflammatory cytokines were suppressed in patients with inflammatory bowel disease who were on ARB therapy compared to patients not receiving ARB therapy. These observations demonstrate that activation of the RAS promotes colitis in a blood pressure independent manner. Angiotensin II appears to drive colonic mucosal inflammation by promoting intestinal epithelial cell apoptosis and mucosal T_H17 responses in colitis development.

1,25-Dihydroxyvitamin D Protects Intestinal Epithelial Barrier by Regulating the Myosin Light Chain Kinase Signaling Pathway

BACKGROUND

The myosin light chain kinase (MLCK) pathway controls intestinal epithelial barrier permeability by regulating the tight junction. 1,25-dihydroxyvitamin D (1,25(OH)2D3)-vitamin D receptor (VDR) signaling protects the epithelial barrier, but the molecular mechanism is incompletely understood.

METHODS

MLCK activation and barrier permeability were studied using monolayers of HCT116, Caco-2, and SW480 cells treated with tissue necrosis factor α with or without 1,25(OH)2D3. The MLCK pathway was analyzed in normal and inflamed colonic biopsies from patients with ulcerative colitis. Colonic mucosal barrier permeability and MLCK activation were also investigated using trinitrobenzene sulfonic acid-induced colitis models in vitamin D analog paricalcitol-treated wild-type mice and mice carrying VDR deletion in colonic epithelial cells.

RESULTS

Tissue necrosis factor α increased cell monolayer permeability and induced long isoform of MLCK expression and myosin II regulatory light chain (MLC) phosphorylation, and 1,25(OH)2D3 blocked tissue necrosis factor α-induced increases in monolayer permeability and MLCK-MLC pathway activation by a VDR-dependent fashion. 1,25(OH)2D3 directly suppressed long MLCK expression by attenuating NF-κB activation, and chromatin immunoprecipitation assays confirmed that 1,25(OH)2D3 disrupted p65 binding to 3 κB sites in long MLCK gene promoter. In human ulcerative colitis biopsies, VDR reduction was associated with increases in long MLCK expression and MLC phosphorylation. In trinitrobenzene sulfonic acid colitis models, paricalcitol ameliorated colitis, attenuated the increase in mucosal barrier permeability, and inhibited long MLCK induction and MLC phosphorylation. In contrast, mice with colonic epithelial VDR deletion exhibited more robust increases in mucosal barrier permeability and MLCK activation compared with wild-type mice.

CONCLUSIONS

These data demonstrate that 1,25(OH)2D3-VDR signaling preserves the mucosal barrier integrity by abrogating MLCK-dependent tight junction dysregulation during colonic inflammation.

The role of CXCR3 in DSS-induced colitis

Inflammatory bowel disease (IBD) is a group of disorders that are characterized by chronic, uncontrolled inflammation in the intestinal mucosa. Although the aetiopathogenesis is poorly understood, it is widely believed that IBD stems from a dysregulated immune response towards otherwise harmless commensal bacteria. Chemokines induce and enhance inflammation through their involvement in cellular trafficking. Reducing or limiting the influx of these proinflammatory cells has previously been demonstrated to attenuate inflammation. CXCR3, a chemokine receptor in the CXC family that binds to CXCL9, CXCL10 and CXCL11, is strongly overexpressed in the intestinal mucosa of IBD patients. We hypothesised that CXCR3 KO mice would have impaired cellular trafficking, thereby reducing the inflammatory insult by proinflammatory cell and attenuating the course of colitis. To investigate the role of CXCR3 in the progression of colitis, the development of dextran sulfate sodium (DSS)-induced colitis was investigated in CXCR3^−/− mice over 9 days. This study demonstrated attenuated DSS-induced colitis in CXCR3^−/− mice at both the macroscopic and microscopic level. Reduced colitis correlated with lower recruitment of neutrophils (p = 0.0018), as well as decreased production of IL-6 (p<0.0001), TNF (p = 0.0038), and IFN-γ (p = 0.0478). Overall, our results suggest that CXCR3 plays an important role in recruiting proinflammatory cells to the colon during colitis and that CXCR3 may be a therapeutic target to reduce the influx of proinflammatory cells in the inflamed colon.

Intestinal epithelial vitamin D receptor signaling inhibits experimental colitis

The inhibitory effects of vitamin D on colitis have been previously documented. Global vitamin D receptor (VDR) deletion exaggerates colitis, but the relative anticolitic contribution of epithelial and nonepithelial VDR signaling is unknown. Here, we showed that colonic epithelial VDR expression was substantially reduced in patients with Crohn's disease or ulcerative colitis. Moreover, targeted expression of human VDR (hVDR) in intestinal epithelial cells (IECs) protected mice from developing colitis. In experimental colitis models induced by 2,4,6-trinitrobenzenesulfonic acid, dextran sulfate sodium, or CD4(+)CD45RB(hi) T cell transfer, transgenic mice expressing hVDR in IECs were highly resistant to colitis, as manifested by marked reductions in clinical colitis scores, colonic histological damage, and colonic inflammation compared with WT mice. Reconstitution of Vdr-deficient IECs with the hVDR transgene completely rescued Vdr-null mice from severe colitis and death, even though the mice still maintained a hyperresponsive Vdr-deficient immune system. Mechanistically, VDR signaling attenuated PUMA induction in IECs by blocking NF-κB activation, leading to a reduction in IEC apoptosis. Together, these results demonstrate that gut epithelial VDR signaling inhibits colitis by protecting the mucosal epithelial barrier, and this anticolitic activity is independent of nonepithelial immune VDR actions.

Risk of colonic cancer is not higher in the obese Lep(ob) mouse model compared to lean littermates

Epidemiological data suggest that obesity increases the risk of colorectal cancer in humans. Given that diet-induced obesity mouse models verified the epidemiological data, the present study aimed to determine whether obese C57BL/6J-Lep(ob) male mice (a different obesity in vivo model) were at greater risk of colonic cancer than their lean male littermates. Risk of colonic tumorigenesis was assessed by numbers of aberrant crypts, aberrant crypt foci and colonic tumors. Proliferation of the colonic epithelia was assessed histochemically following administration of BrdU. Availability of the procarcinogen, azoxymethane (AOM) to target tissues was assessed by quantifying via HPLC plasma AOM concentrations during the 60 min period following AOM injection. When obese and lean mice were injected with azoxymethane (AOM) at doses calculated to provide equivalent AOM levels per kg lean body mass, obese animals had significantly fewer aberrant crypts/colon and fewer aberrant crypt foci/colon than the lean animals. Tumors were identified in the colonic mucosa of lean (4 tumors in 14 mice) but not obese (0 tumors in 15 mice) mice. Colonic cell proliferation was not significantly different for obese and lean mice. Because these results were unexpected, plasma AOM concentrations were measured and were found to be lower in the obese than lean mice. When plasma AOM levels were comparable for the lean and obese mice, the Lep(ob) mice continued to have significantly fewer aberrant crypt foci/colon than the lean mice, but differences were not statistically different for aberrant crypts/colon. Interestingly, obese Lep(ob) mice did not exhibit increased risk of colonic cancer as expected. Instead, Lep(ob) mice exhibited equivalent or lower risk of colon cancer when compared to the lean group. These results taken together with in vivo results from diet-induced obesity studies, imply that leptin may be responsible for the increased risk of colon cancer associated with obesity.

Familial gastric cancer: guidelines for diagnosis, treatment and periodic surveillance

Hereditary diffuse gastric cancer (HDGC) is a relatively rare disorder, with a mutated CDH1 gene as the only known cause. Carriers of a germline mutation in CDH1 have a lifetime risk of >80% of developing diffuse gastric cancer. As periodic gastric surveillance is of limited value in detecting early stages of HDGC, prophylactic gastrectomy is advised for this patient group. Little is known about other types of familial gastric cancer. The Dutch working group on hereditary gastric cancer has formulated guidelines for various aspects of medical management for families and individuals at high risk of developing gastric cancer, including criteria for referral, classification, diagnostics, and periodic gastric surveillance. These guidelines are not limited to HDGC and are therefore partially complementary to the guidelines on hereditary diffuse gastric cancer of the international gastric cancer linkage consortium (IGCLC 2010). In order to optimize the care and increase the knowledge on hereditary gastric cancer it is important to centralize medical care for these patients. National and international collaboration is warranted to improve the quality of research by increasing the size of study cohorts.

Loss of function of the mouse Sharpin gene results in Peyer's patch regression

Peyer’s patches (PP) are an important component in the immune response against intestinal pathogens. Two independent, spontaneous mutations in the mouse Sharpin gene (Sharpin^cpdm and Sharpin^cpdm-Dem) result in the absence of PP and disrupted splenic white pulp in adult mice, although a full complement of lymph nodes is present. Here we report that rudimentary PP begin to develop in Sharpin^cpdm mice during embryogenesis, but lack the organizational patterns that are typical of this tissue. In the present study, small intestines examined at weekly intervals from birth to maturity showed spontaneous regression of PP in mutant mice with concurrent infiltration of granulocytes. At 5 to 6 weeks of age, only indistinct remnants of granulocytic accumulations remain. Transplantation of normal bone marrow into Sharpin^cpdm mice at 7 days of age did not prevent regression of PP in bone marrow chimeras examined at 7 to 8 weeks of age. These findings indicate that SHARPIN expression is required for the normal development and maintenance, but not initiation, of PP.

Familial gastric cancer: detection of a hereditary cause helps to understand its etiology

Worldwide, gastric cancer is one of the most common forms of cancer, with a high morbidity and mortality. Several environmental factors predispose to the development of gastric cancer, such as Helicobacter pylori infection, diet and smoking. Familial clustering of gastric cancer is seen in 10% of cases, and approximately 3% of gastric cancer cases arise in the setting of hereditary diffuse gastric cancer (HDGC). In families with HDGC, gastric cancer presents at relatively young age. Germline mutations in the CDH1 gene are the major cause of HDGC and are identified in approximately 25-50% of families which fulfill strict criteria. Prophylactic gastrectomy is the only option to prevent gastric cancer in individuals with a CDH1 mutation. However, in the majority of families with multiple cases of gastric cancer no germline genetic abnormality can be identified and therefore preventive measures are not available, except for general lifestyle advice. Future research should focus on identifying new genetic predisposing factors for all types of familial gastric cancer.

Multifactorial patterns of gene expression in colonic epithelial cells predict disease phenotypes in experimental colitis

BACKGROUND

The pathogenesis of inflammatory bowel disease (IBD) is complex and the need to identify molecular biomarkers is critical. Epithelial cells play a central role in maintaining intestinal homeostasis. We previously identified five "signature" biomarkers in colonic epithelial cells (CEC) that are predictive of disease phenotype in Crohn's disease. Here we investigate the ability of CEC biomarkers to define the mechanism and severity of intestinal inflammation.

METHODS

We analyzed the expression of RelA, A20, pIgR, tumor necrosis factor (TNF), and macrophage inflammatory protein (MIP)-2 in CEC of mice with dextran sodium sulfate (DSS) acute colitis or T-cell-mediated chronic colitis. Factor analysis was used to combine the five biomarkers into two multifactorial principal components (PCs). PC scores for individual mice were correlated with disease severity.

RESULTS

For both colitis models, PC1 was strongly weighted toward RelA, A20, and pIgR, and PC2 was strongly weighted toward TNF and MIP-2, while the contributions of other biomarkers varied depending on the etiology of inflammation. Disease severity was correlated with elevated PC2 scores in DSS colitis and reduced PC1 scores in T-cell transfer colitis. Downregulation of pIgR was a common feature observed in both colitis models and was associated with altered cellular localization of pIgR and failure to transport IgA.

CONCLUSIONS

A multifactorial analysis of epithelial gene expression may be more informative than examining single gene responses in IBD. These results provide insight into the homeostatic and proinflammatory functions of CEC in IBD pathogenesis and suggest that biomarker analysis could be useful for evaluating therapeutic options for IBD patients.

CDH1-related hereditary diffuse gastric cancer syndrome: clinical variations and implications for counseling

CDH1 mutation carriers have a strongly increased risk of developing gastric cancer (GC) and lobular breast cancer (LBC). Clinical data of GC cases and surgical and histological data of prophylactic gastrectomies and mastectomies of all 10 Dutch CDH1 mutation families were collected. In vitro functional assays were performed to analyze the nature of the newly found missense mutation c.1748T>G (p.Leu583Arg). Ten different CDH1 mutations were found. Functional assays gave strong arguments for the pathogenic nature of the p.Leu583Arg mutation. The pedigrees comprised 36 GC cases (mean age 40 years, range 20-72 years) and one LBC case. Twenty-nine/37 carriers alive, aged 18-61 years, underwent prophylactic gastrectomy. Invasive GC-foci and premalignant abnormalities were detected in 2 and 25 patients, respectively. In four patients GC/signetring cell (SRC) foci were diagnosed at preoperative gastroscopy. Long-standing presence of SRCs without progression to invasive carcinoma was shown in two others. Multifocal LBC/LCIS was found in the two prophylactic mastectomy specimens. Clefts of lip and/or palate (CL/P) were reported in seven individuals from three families. The age at onset and aggressiveness of GC is highly variable, which has to be included in counseling on planning prophylactic gastrectomies. The incidence of LBC is expected to increase and prophylactic mastectomy needs to be considered. The relationship between CL/P and CDH1 needs further study to inform future parents from hereditary diffuse gastric cancer (HDGC) families adequately.

Vitamin D receptor negatively regulates bacterial-stimulated NF-kappaB activity in intestine

Vitamin D receptor (VDR) plays an essential role in gastrointestinal inflammation. Most investigations have focused on the immune response; however, how bacteria regulate VDR and how VDR modulates the nuclear factor (NF)-kappaB pathway in intestinal epithelial cells remain unexplored. This study investigated the effects of VDR ablation on NF-kappaB activation in intestinal epithelia and the role of enteric bacteria on VDR expression. We found that VDR(-/-) mice exhibited a pro-inflammatory bias. After Salmonella infection, VDR(-/-) mice had increased bacterial burden and mortality. Serum interleukin-6 in noninfected VDR(+/+) mice was undetectable, but was easily detectable in VDR(-/-) mice. NF-kappaB p65 formed a complex with VDR in noninfected wild-type mouse intestine. In contrast, deletion of VDR abolished VDR/P65 binding. P65 nuclear translocation occurred in colonic epithelial cells of untreated VDR(-/-) mice. VDR deletion also elevated NF-kappaB activity in intestinal epithelia. VDR was localized to the surface epithelia of germ-free mice, but to crypt epithelial cells in conventionalized mice. VDR expression, distribution, transcriptional activity, and target genes were regulated by Salmonella stimulation, independent of 1,25-dihydroxyvitamin D3. Our study demonstrates that commensal and pathogenic bacteria directly regulate colonic epithelial VDR expression and location in vivo. VDR negatively regulates bacterial-induced intestinal NF-kappaB activation and attenuates response to infection. Therefore, VDR is an important contributor to intestinal homeostasis and host protection from bacterial invasion and infection.

Histochemical analysis of glycoproteins in the secretory cells in the gill epithelium of a catfish, Rita rita (Siluriformes, Bagridae)

Glycoproteins (GPs) were visualised histochemically in the secretory cells - the mucous goblet cells (the type A and the type B), the serous goblet cells, the club cells and the epithelial cells in the gill epithelium of Rita rita. The type A mucous goblet cells, the type B mucous goblet cells and the epithelial cells elaborate GPs with oxidizable vicinal diols and GPs with sialic acid residue without O-acyl substitution. In addition, GPs with O-sulphate esters are elaborated by the type A and GPs with O-acyl sugars by the type B mucous goblet cells. GPs are absent in the serous goblet cells and are with oxidizable vicinal diols in low moieties in the club cells. The analysis of the results elucidates interesting differences in the composition and concentration of GPs in the mucus elaborated by the epithelium of the gill arches and the gill rakers; and the gill filaments and the secondary lamellae indicating the potential importance of the glycoproteins at these locations. GPs elaborated on the surfaces of the gill arches and the gill rakers could be associated to assist in feeding activities and on the surfaces of the gill filaments and the secondary lamellae in the respiratory activity.

Alternative medicine products as a novel treatment strategy for inflammatory bowel disease

Inflammatory bowel disease (IBD) affects the mucosal lining of the gastrointestinal tract; the etiology is unknown and treatment is directed at systemic immunosuppression. Natural products, including medicinal herbs, have provided approximately half of the drugs developed for clinical use over the past 20 years. The purpose of our current study was to determine the effects of a novel combination of herbal extracts on intestinal inflammation using a murine model of IBD. Female Swiss-Webster mice were randomized to receive normal water or 5% dextran sulfate sodium (DSS) drinking water to induce colitis. Mice were treated with either a novel combination of herbal aqueous extracts or vehicle control per os (po) or per rectum (pr) every 24 hours for 7-8 days. Disease activity index score (DAI) was determined daily; mice were sacrificed and colons were analyzed by H & E staining, MPO assay, and cytokine (TNF-alpha, IL-6) ELISAs. Mice treated with the combination of herbal extracts, either po or pr, had significantly less rectal bleeding and lower DAI scores compared to the vehicle-treated group. Moreover, colonic ulceration, leukocytic infiltration, and cytokine levels (TNF-alpha and IL-6) were also decreased in the colons of herbal-treated mice, reflected by H & E staining, MPO assay, and cytokine ELISA. Treatment with the combination of medicinal herbs decreases leukocyte infiltration and mucosal ulceration, ameliorating the course of acute colonic inflammation. This herbal remedy may prove to be a novel and safe therapeutic alternative in the treatment of IBD.

Novel role of the vitamin D receptor in maintaining the integrity of the intestinal mucosal barrier

Emerging evidence supports a pathological link between vitamin D deficiency and the risk of inflammatory bowel disease (IBD). To explore the mechanism we used the dextran sulfate sodium (DSS)-induced colitis model to investigate the role of the vitamin D receptor (VDR) in mucosal barrier homeostasis. While VDR(+/+) mice were mostly resistant to 2.5% DSS, VDR(-/-) mice developed severe diarrhea, rectal bleeding, and marked body weight loss, leading to death in 2 wk. Histological examination revealed extensive ulceration and impaired wound healing in the colonic epithelium of DSS-treated VDR(-/-) mice. Severe ulceration in VDR(-/-) mice was preceded by a greater loss of intestinal transepithelial electric resistance (TER) compared with VDR(+/+) mice. Confocal and electron microscopy (EM) revealed severe disruption in epithelial junctions in VDR(-/-) mice after 3-day DSS treatment. Therefore, VDR(-/-) mice were much more susceptible to DSS-induced mucosal injury than VDR(+/+) mice. In cell cultures, 1,25-dihydroxy-vitamin D(3) [1,25(OH)(2)D(3)] markedly enhanced tight junctions formed by Caco-2 monolayers by increasing junction protein expression and TER and preserved the structural integrity of tight junctions in the presence of DSS. VDR knockdown with small interfering (si)RNA reduced the junction proteins and TER in Caco-2 monolayers. 1,25(OH)(2)D(3) can also stimulate epithelial cell migration in vitro. These observations suggest that VDR plays a critical role in mucosal barrier homeostasis by preserving the integrity of junction complexes and the healing capacity of the colonic epithelium. Therefore, vitamin D deficiency may compromise the mucosal barrier, leading to increased susceptibility to mucosal damage and increased risk of IBD.

Protective roles of alpha-calcitonin and beta-calcitonin gene-related peptide in spontaneous and experimentally induced colitis

Calcitonin gene-related peptide (CGRP) is thought to be involved in the regulation of gastric and mesenteric blood flow, in the control of gastric acid secretion and in the modulation of intestinal motility, yet the precise physiological roles of CGRP remain to be elucidated. To further examine the role(s) of CGRP in gastrointestinal function, we examined mutant mice lacking alphaCGRP or betaCGRP expression. Mutant mice did not demonstrate any overt phenotypic changes, yet exhibited a spontaneous, adult-onset colitis and increased colonic damage using a dextran sulfate sodium model of experimental colitis. Surprisingly, mice lacking betaCGRP show no obvious alterations in CGRP immunoreactivity in the gut, accompanied by an increase in alphaCGRP messenger RNA expression, suggesting an adaptive mechanism to compensate for the lack of betaCGRP. These data demonstrate that both alphaCGRP and betaCGRP play a protective role in the generation of spontaneous colitis, supporting a role for both extrinsic and intrinsic CGRP-containing neurons.

A vitamin D analogue inhibits colonic carcinogenesis in the AOM/DSS model

BACKGROUND

The azoxymethane (AOM) model recapitulates many features of human colon cancer, lacking an inflammatory component. Dextran sulfate sodium (DSS) induces colitis and promotes AOM-induced colon cancer in mice. Vitamin D analogues are anti-inflammatory and chemopreventive in models of colon cancer. Our aim was to evaluate the anti-inflammatory and chemopreventive efficacy of the vitamin D analogue Ro26-2198 in the AOM/DSS model and in vitro in HCA-7 colon cancer cells.

MATERIALS AND METHODS

A/J mice received Ro26-2198 (0.01 microg/kg body wt/day x 28 days) or vehicle by mini-osmotic pump. Animals were treated with a single dose of AOM (5 mg/kg body wt) or vehicle 1 week after pump insertion. Mice received 3% DSS or water x 7 days beginning week 3. Animals were sacrificed after 8 weeks and colon segments were fixed in formalin or flash-frozen. Hematoxylin and eosin colonic sections were examined for dysplasia and colonic lysates were assessed for c-Myc, cyclooxygenase 2, and phospho-(active) extracellular signal regulated kinase (ERK) by Western blotting. For in vitro studies, HCA-7 cells were treated with Ro26-2198 followed by interleukin-1beta (IL-1beta). Proliferation was measured by WST-1 assay.

RESULTS

Ro26-2198 delayed the onset of clinical colitis. Several dysplastic foci were present in the AOM/DSS group; none were found in the Ro26-2198 group. Compared with control, AOM/DSS significantly increased c-Myc (15-fold), cyclooxygenase 2 (COX-2) (2.5-fold), and pERK (10-fold), and Ro26-2198 abolished these increases. In vitro, Ro26-2198 inhibited IL-1beta-induced ERK activation and COX-2 induction and decreased HCA-7 cell proliferation.

CONCLUSIONS

Ro26-2198 inhibited proliferative (ERK, c-Myc) and pro-inflammatory (COX-2) signals and progression to dysplasia, suggesting chemopreventive efficacy in this model of colitis-associated carcinogenesis.

Folate Transport Gene Inactivation in Mice Increases Sensitivity to Colon Carcinogenesis

Low dietary folate intake is associated with an increased risk for colon cancer; however, relevant genetic animal models are lacking. We therefore investigated the effect of targeted ablation of two folate transport genes, folate binding protein 1 (Folbp1) and reduced folate carrier 1 (RFC1), on folate homeostasis to elucidate the molecular mechanisms of folate action on colonocyte cell proliferation, gene expression, and colon carcinogenesis. Targeted deletion of Folbp1 (Folbp1+/− and Folbp1−/−) significantly reduced (P &lt; 0.05) colonic Folbp1 mRNA, colonic mucosa, and plasma folate concentration. In contrast, subtle changes in folate homeostasis resulted from targeted deletion of RFC1 (RFC1+/−). These animals had reduced (P &lt; 0.05) colonic RFC1 mRNA and exhibited a 2-fold reduction in the plasma S-adenosylmethionine/S-adenosylhomocysteine. Folbp1+/− and Folbp1−/− mice had larger crypts expressed as greater (P &lt; 0.05) numbers of cells per crypt column relative to Folbp1+/+ mice. Colonic cell proliferation was increased in RFC1+/− mice relative to RFC1+/+ mice. Microarray analysis of colonic mucosa showed distinct changes in gene expression specific to Folbp1 or RFC1 ablation. The effect of folate transporter gene ablation on colon carcinogenesis was evaluated 8 and 38 weeks post-azoxymethane injection in wild-type and heterozygous mice. Relative to RFC1+/+ mice, RFC1+/− mice developed increased (P &lt; 0.05) numbers of aberrant crypt foci at 8 weeks. At 38 weeks, RFC1+/− mice developed local inflammatory lesions with or without epithelial dysplasia as well as adenocarcinomas, which were larger relative to RFC1+/+ mice. In contrast, Folbp1+/− mice developed 4-fold (P &lt; 0.05) more lesions relative to Folbp1+/+ mice. In conclusion, Folbp1 and RFC1 genetically modified mice exhibit distinct changes in colonocyte phenotype and therefore have utility as models to examine the role of folate homeostasis in colon cancer development.

Are dietary fiber-induced alterations in colonic epithelial cell proliferation predictive of fiber's effect on colon cancer?

Alterations in cell proliferation of the colon have been observed as a result of changes in amount and type of dietary fiber and in relation to risk of developing colon cancer. Although some human observational and intervention studies contribute to the database, most information results from experiments on rodents. Because of numerous contradictory reports linking dietary fiber, cell proliferation, and colon cancer, we undertook a critical review of existing methods in an attempt to explain the inconsistencies. Although there may be some individual types of dietary fiber that protect against chemically induced colon cancer, dietary fiber as a single entity does not appear to afford any consistent protection. Because of significant differences in experimental protocols among laboratories, it is not yet possible to state with certainty that increases in cell proliferation, induced by fiber consumption, are predictive of increased tumorigenesis. Much of what has been observed and interpreted as elevation of risk may simply be normal homeostatic changes in cell proliferation. Even though fermentation to short-chain fatty acids is a mechanistically attractive hypothesis to explain why fiber modulates cytokinetics, data do not consistently support short-chain fatty acids as biological intermediates in risk of colon cancer. The state of the art in this field has not yet progressed to the point where a clear effect of dietary fiber on cytokinetics and colon carcinogenesis can be assessed with any degree of certainty. Additional markers of apoptosis, differentiation, and cell-cell communication may be required for a more accurate analysis of the relation among fiber, cytokinetics, and colon cancer.

Histochemical, lectin-histochemical and morphometrical characteristics of intestinal goblet cells of germfree and conventional mice

Histochemical, lectin-histochemical and morphometrical studies were carried out on intestinal goblet cells of 8-week-old germfree (GF) and conventional (CV) mice of the BALB/c strain. Except for the reactivity of cecal goblet cells to Dolichos biflorus agglutinin (DBA) and Ulex europeus-I agglutinin (UEA-I), there was no difference between GF and CV mice in histochemical and lectin-histochemical properties. In the cecal mucosa, DBA stained the goblet cells strongly in CV mice but not in GF mice and UEA-I stained the goblet cells strongly in the lower part of crypts in CV mice but only faintly in GF mice. These findings suggest that terminal residues of cecal goblet cell mucin were different in GF and CV mice. Morphometrically, cecal goblet cells were fewer in number and smaller in size in GF mice than in CV mice. In addition, high iron diamine-alcian blue staining made a very clear border between the cecum and colon, because cecal goblet cells were exclusively positive for sulfomucin and colonic goblet cells were predominantly positive for sialomucin.

Histochemical studies of intestinal epithelial goblet cell glycoproteins during the development of the human foetus

Histochemical studies performed on specimens of intestine from 12 to 37-week human foetuses showed that the epithelial glycoproteins of the goblet cells of the small intestine are non-sulphated sialoglycoproteins containing neutral sugar (hexose, 6-deoxy hexose or N-acetyl hexosamine residues with Periodic acid-Schiff (PAS) reactive vicinal diols), sialic acids without O-acyl substituents, smaller and variable quantities of sialic acids with O-acyl substituents at positions C8 or C9 (or with two or three side chain substituents) and O-acyl sugars (neutral sugars with an ester substituent blocking PAS reactivity). In the lower small intestine glycoproteins containing 8 (or 9)-O-acyl sialic acids are first observed in goblet cells at the tips of the villi. As the foetus matures their quantity increases and they are found in goblet cells located along the length of the villi. Smaller quantities of O-acyl sialic acids and traces of O-acyl sugars occur in the goblet cells of the upper small intestine. The colonic goblet cells contain sulphosialoglycoproteins of two types. The first type, found in the majority of specimens, contains O-sulphate ester, neutral sugar, O-acyl sugars and 8 (or 9)-O-acyl sialic acids. The second type contains O-sulphate ester, neutral sugars, and sialic acids which are either without side chain O-acyl substituents or are a mixture of such acids and 8 (or 9)-O-acyl sialic acids; O-acyl sugars are reduced or absent.(ABSTRACT TRUNCATED AT 250 WORDS)

The histochemical specificity of high iron diamine-alcian blue

The specificity of the High Iron Diamine-Alcian Blue pH 2.5 (HID-AB 2.5) procedure was examined in tissue sites containing sialogycoproteins alone or differing proportions of sialo- and sulphosialoglycoproteins. Studies with HID in differing final concentrations of hydrochloric acid or sodium chloride confirmed that staining is dependent upon both the pH and the ionic strength of the dye bath and demonstrated a marked heterogeneity in the pKa of the anionic groups of sialosulphoglycoproteins. Use of the sequence High Iron Diamine-Alcian Blue pH 1.0 demonstrated that complete or almost complete staining of O-sulphate esters occurred when HID was prepared in water (final pH 1.3). However, under these conditions HID-AB 2.5 was shown to be non-specific because only black HID staining was observed in sites containing large quantities of sialic acids. This non-specificity was due either to the masking of Alcian Blue staining by HID and/or the black HID staining of anionic groups other than sulphate. These results may account for some of the conflicting data obtained by different groups of investigators who have studied 'transitional mucosa' in human colonic diseases. Caution should be used in drawing conclusions from the use of HID-AB 2.5 without confirmatory evidence from other more specific procedures.

Histochemical studies of the colonic epithelial glycoproteins of the normal rabbit

Two general classes of glycoproteins have been identified in the colonic epithelial cells of New Zealand white rabbits. Each is associated with an ultrastructurally distinct secretory cell. The first of these classes is found in cells, termed vesiculated columnar cells, characterized by electron-translucent vesicles, a small rough endoplasmic reticulum-Golgi complex and prominent microvilli. The glycoproteins of the vesiculated cells contain abundant O-sulphate ester, sialic acids with ester substituents at positions C-8 or C-9 (or with two or three side chain substituents) and neutral sugars with vicinal diols whose periodate oxidation is prevented by an O-acyl ester substituent(s). The second class of glycoproteins occurs in goblet cells characterized by electron-dense vesicles, an abundant rough endoplasmic reticulum, a well-developed Golgi apparatus and few, if any, microvilli. Goblet cells along the entire length of the crypts contain neutral sugars with periodate-oxidisable vicinal diols and a ferriferricyanide-reactive component. Cells in the upper halves of the crypts also contain components that are sulphated, Schiff-reactive and acid-fast. In the lower halves of the crypts, the goblet cells contain smaller quantities of the above components plus sialic acids, some of which possibly have an O-acyl substituent located at position C-8 or C-9 (or which have two or three side chain O-acyl substituents). It is suggested that the function of the glycoproteins from the vesiculated columnar cells is protective and that from the goblet cells is lubricative.

Simple procedure for assessing relative quantities of neutral and acidic sugars in mucin glycoproteins: its use in assessing cyclical changes in cervical mucins

A simple histochemical procedure for assessing relative amounts of neutral and acidic sugars in mucin glycoproteins, and its application in the study of cyclical changes of human cervical mucins, is described. This procedure, the saponification/selective periodate oxidation/borohydride reduction/alcian blue pH 2.5/periodic acid Schiff (KOH/PA*/Bh/Ab 2.5/PAS) method, uses a selective oxidation step to remove the PAS positivity of sialic acid; thus only neutral sugars stain positively with PAS, and acidic sugars (O-sulphate esters and carboxyl groups) stain with alcian blue. This differs from the KOH/Ab/PAS technique which stains sialic acid residues with both alcian blue and PAS. Applying the KOH/PA*/Bh/Ab 2.5/PAS technique to the study of cyclical changes of human cervical mucins, a decreased neutral:acidic sugar ratio in the secretory phase mucins compared with those of the proliferative phase was found. This difference was not seen with KOH/Ab/PAS staining in the same cases. The techniques and reagents used in this procedure can be easily applied in a clinical histopathology laboratory.

A new method for the histochemical demonstration of O-acyl sugars in human colonic epithelial glycoproteins

A new general method has been developed for the specific histochemical identification of O-acyl sugars in any epithelial glycoprotein. These sugars include hexose, 6-deoxyhexose and N-acetylhexosamine with an ester substituent(s) located on a potential vicinal diol(s). In the procedure reported [the periodic acid-borohydride reduction-saponification-selective periodate oxidation-borohydride reduction-periodic acid-Schiff (PA-Bh-KOH-PA*-Bh-PAS) method] the initial PA-Bh treatment renders vicinal diols located on either sialic acid or neutral sugars PAS unreactive. In the subsequent steps ester substituents are removed from both O-acyl sugars and O-acyl sialic acids by saponification (KOH), sialic acid vicinal diols are selectively removed by the PA*-Bh sequence and O-acyl sugars are stained with the PAS technique. This method has the advantage that the results are obtained with a single section and the results are either positive or negative. Consequently, it is superior to the three indirect methods investigated because it does not require an observer to compare the intensity or the shade of the staining obtained with serial sections. Using the PA-Bh-KOH-PA*-Bh-PAS method we have demonstrated, for the first time, that O-acyl sugars occur in the epithelial goblet cell glycoproteins of adult human colon. The effect of the presence of O-acyl sugars on the interpretation of a number of other methods for the histochemical investigation of glycoproteins is discussed. It is recommended that the results obtained with the PA-Bh-KOH-PA*-Bh-PAS method be evaluated before histochemical procedures for the investigation of neutral sugars and O-acyl sialic acids are selected.

Histochemical studies of epithelial cell glycoproteins in normal rat colon

Two general classes of glycoproteins have been identified in the colonic epithelial cells of the Sprague Dawley rat. Glycoproteins belonging to the first of these classes contain sialic acids both with and without side chain o-acyl substituents, abundant o-sulphate ester and 'neutral sugars' (hexose, 6-deoxyhexose or N-acetyl hexosamine residues) with oxidisable vicinal diols and are located in the goblet cells of the descending colon and in goblet cells populating the upper halves of the crypts of the ascending colon. In the descending colon, the sulphosialoglycoproteins in the goblet cells in the base of the crypts contain sialic acids without side chain o-acyl substituents. It appears that as these cells migrate up the crypts, there is o-acylation of the side chains of the sialic acids of the glycoproteins and an increase in the quantity of 'neutral sugars' without a corresponding increase in sialic acid. Glycoproteins with similar properties to those of the goblet cells of the upper halves of the crypts of the descending colon, but containing less sulphate, are found in the goblet cells of the upper half of the crypts of the ascending colon. The second general class of glycoproteins contain sialic acids all, or almost all of which, are substituted at position C8 and only relatively small quantities of sulphate. They are located in the mucous cells of the descending colon, the deep crypt secretory cells of the ascending colon and the columnar absorptive cell brush border.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological and histochemical changes in intestinal mucosa in the reserpine-treated rat model of cystic fibrosis

The present investigation was undertaken to determine whether or not there are histochemical and morphological changes in the intestine of the chronically reserpine-treated rat, an animal model of cystic fibrosis. Male Sprague-Dawley rats were given seven daily intraperitoneal injections of reserpine at dosages of 0.5 (n = 6) or 1.0 mg/kg body weight (n = 6). Control groups consisted of parfed solvent-injected (n = 6), solvent-injected (n = 4), and saline-injected animals (n = 4). Light microscopic histochemical procedures and morphological assessments were performed on sections of "Swiss rolls" of small and large intestine. Chronic reserpine treatment caused an increase in the sulfation of goblet cell mucin in the small intestine without accompanying morphological change; these findings resemble those reported in cystic fibrosis. No qualitative differences in mucin were found in the large intestine but there was an increased number of goblet cells in the surface epithelium and retention of mucus within these cells. Similar although less marked changes were noted in the parfed controls suggesting that those observed in the treated groups may be due, in part, to the reserpine-induced anorexia. The resemblance between the changes in the small intestine of the reserpine-treated rat and those observed in CF patients supports the contention that the chronically reserpine-treated rat is suitable as a model of cystic fibrosis.