The "Swiss roll": a simple technique for histological studies of the rodent intestine

NCOR1 Orchestrates Transcriptional Landscapes and Effector Functions of CD4+ T Cells

The differentiation of naïve CD4+ T cells into T helper (Th) subsets is key for a functional immune response and has to be tightly controlled by transcriptional and epigenetic processes. However, the function of cofactors that connect gene-specific transcription factors with repressive chromatin-modifying enzymes in Th cells is yet unknown. Here we demonstrate an essential role for nuclear receptor corepressor 1 (NCOR1) in regulating naïve CD4+ T cell and Th1/Th17 effector transcriptomes. Moreover, NCOR1 binds to a conserved cis-regulatory element within the Ifng locus and controls the extent of IFNγ expression in Th1 cells. Further, NCOR1 controls the survival of activated CD4+ T cells and Th1 cells in vitro, while Th17 cell survival was not affected in the absence of NCOR1. In vivo, effector functions were compromised since adoptive transfer of NCOR1-deficient CD4+ T cells resulted in attenuated colitis due to lower frequencies of IFNγ+ and IFNγ+IL-17A+ Th cells and overall reduced CD4+ T cell numbers. Collectively, our data demonstrate that the coregulator NCOR1 shapes transcriptional landscapes in CD4+ T cells and controls Th1/Th17 effector functions.

An approach for visualizing the spatial metabolome of an entire plant root system inspired by the Swiss-rolling technique

The spatial configuration and morphology of roots are commonly monitored for a better understanding of plant health and development. However, this approach provides minimal details about the biochemistry regulating the observable traits. Therefore, the ability to metabolically map the entire root structure would be of major value. Here, we developed a sample preparation approach that enables imaging of the entire root within a restricted space (width of microscope slide), which was influenced by the Swiss-rolling technique. We were able to image and confidently identify molecules along the entire root structure from rolled-root tissue sections using multiple spatially resolved mass spectrometry approaches.

Participation of Somatic Stem Cells, Recognized by a Unique A3 Antibody, in Mucosal Epithelial Regeneration in Dextran Sulfate Sodium (DSS)-Induced Rat Colonic Lesions

A3, generated as a monoclonal antibody against rat malignant fibrous histiocytoma cells, recognizes somatic stem cells in rats. We analyzed the distribution of A3-positive cells in dextran sulfate sodium (DSS)-induced colonic lesions consisting of regenerating mucosa and fibrosis. Male 6-week-old F344 rats were administered 5% DSS in drinking water for 5 to 7 days, and lesions at recovery stage were also examined. In untreated control adult colons, A3-positive cells are localized around the crypts where stem cell niche is formed. Histopathologically, in colons of DSS-administered rats, mucosal atrophy, inflammatory cell infiltration, and fibrosis were observed in the lamina propria; thereafter, mucosal epithelia were desquamated, and crypts were decreased gradually with decrease in surrounding A3-positive cells. At the early recovery stage, crypts showed regeneration with reappearance of A3-positive cells. Interestingly, A3-positive cells aggregated in desquamated mucosa surface of fibrosis. Aggregated A3-positive cells coexpressed with vimentin, Thy-1, and partly CK19 but did not react simultaneously with α-SMA. Likely, aggregated A3-positive cells may be rescue cells with nature of both mesenchymal and epithelial cells to maintain self-renewal after injury in the colon. A3 antibody would become a useful tool to investigate the participation of stem cells in rat colonic lesions.

Nonproliferative and Proliferative Lesions of the Rat and Mouse Hematolymphoid System

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative changes in rats and mice. The purpose of this publication is to provide a standardized nomenclature for classifying changes observed in the hematolymphoid organs, including the bone marrow, thymus, spleen, lymph nodes, mucosa-associated lymphoid tissues, and other lymphoid tissues (serosa-associated lymphoid clusters and tertiary lymphoid structures) with color photomicrographs illustrating examples of the lesions. Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. The nomenclature for these organs is divided into 3 terminologies: descriptive, conventional, and enhanced. Three terms are listed for each diagnosis. The rationale for this approach and guidance for its application to toxicologic pathology are described in detail below.

A mouse model of Staphylococcus aureus small intestinal infection

Introduction

Staphylococcus aureus is a recognised cause of foodborne intoxication and antibiotic-associated diarrhoea (AAD), which are both mediated by staphylococcal enterotoxins. However, unlike foodborne intoxication, AAD appears to require infection of the host. While S. aureus intoxication is widely studied, little is known about S. aureus pathogenesis in the context of gastrointestinal infection.

Aim

To develop a mouse model of S. aureus gastrointestinal infection.

Methodology

An established AAD mouse model was adapted for S. aureus infection, and damage observed via histopathological analysis and immunostaining of intestinal tissues.

Results

Various strains colonised the mouse model, and analysis showed that although clinical signs of disease were not seen, S. aureus infection induced damage in the small intestine, disrupting host structures essential for epithelial integrity. Studies using a staphylococcal enterotoxin B mutant showed that this toxin may contribute to damage during gastrointestinal infection.

Conclusion

This work presents a new mouse model of S. aureus gastrointestinal infection, while also providing insight into the pathogenesis of S. aureus in the gut.

Role of the δ-Opioid Receptor in 2 Murine Models of Colitis

Crohn disease and ulcerative colitis, collectively referred to as inflammatory bowel disease (IBD), are chronic inflammatory disorders of the gastrointestinal tract. Currently, the etiology of IBD is unknown, and immunosuppressive therapies have become the standard of care to reduce the inflammation; however, these agents only induce remission 50% of the time in patients and can have serious side effects. Recently, endogenous opioids and opioid receptors have been shown to play a role in the mediation of inflammation. In addition, opioid receptor blockade with a nonselective antagonist, naltrexone, has been shown to reduce colitis in both murine models and human subjects. The goal of the current study was to determine if the antiinflammatory effects of naltrexone are mediated through the delta (δ) opioid receptor. Male C57BL/6NCrl (6 to 8 wk.; n = 110) and female BALB/cAnNCrl (6-8 wk.; n = 91) mice were studied using 2 animal models of chemically induced colitis: dextran sodium sulfate (DSS) and 2, 4, 6-trinitrobenzenesulfonic acid (TNBS). The selective δ-receptor antagonists naltrindole and 7-benzylidenenaltrexone were administered to examine the role of the δ-opioid receptor in colonic inflammation. The quantitative measurement of colitis activity, colon weight and length, Hct, WBC count, and gross and microscopic aberrations were analyzed. Administration of naltrexone in the DSS colitis model significantly improved overall disease activity indices on day 5 of therapy. The use of δ-antagonists and naltrexone had limited to no effect on TNBS colitis. Similar findings were obtained by using the DSS colitis model. Based on the current findings, the authors conclude that naltrexone therapy has limited effect on the improvement of colitis in 2 murine models; however, the δ-opioid receptor was not responsible for mediating the effects.

Switching to a Healthy Diet Prevents the Detrimental Effects of Western Diet in a Colitis-Associated Colorectal Cancer Model

Inflammatory bowel disease increases the odds of developing colitis-associated cancer. We hypothesized that Western-style diet (WD) aggravates azoxymethane (AOM)/dextran sulfate sodium salt (DSS)-induced colitis-associated tumorigenesis and that switching to the standard AIN93G diet will ameliorate disease symptoms even after cancer initiation. Female BALB/c mice received either WD (WD group) or standard AIN93G diet (AIN group) for the whole experimental period. After five weeks, the mice received 12.5 mg/kg AOM intraperitoneally, followed by three DSS cycles. In one group of mice, the WD was switched to AIN93G the day before starting the first DSS cycle (WD/AIN group). Feeding the WD during the whole experimental period aggravated colitis symptoms, shortened the colon (p < 0.05), changed microbiota composition and increased tumor promotion. On molecular level, the WD reduced proliferation (p < 0.05) and increased expression of the vitamin D catabolizing enzyme Cyp24a1 (p < 0.001). The switch to the AIN93G diet ameliorated this effect, reflected by longer colons, fewer (p < 0.05) and smaller (p < 0.01) aberrant colonic crypt foci, comparable with the AIN group. Our results show that switching to a healthy diet, even after cancer initiation is able to revert the deleterious effect of the WD and could be an effective preventive strategy to reduce colitis symptoms and prevent tumorigenesis.

Toll-like Receptor-6 Signaling Prevents Inflammation and Impacts Composition of the Microbiota During Inflammation-Induced Colorectal Cancer

Tightly regulated immune responses must occur in the intestine to avoid unwanted inflammation, which may cause chronic sequela leading to diseases such as colorectal cancer. Toll-like receptors play an important role in preventing aberrant immune responses in the intestine by sensing endogenous commensal microbiota and delivering important regulatory signals to the tissue. However, the role that specific innate receptors may play in the development of chronic inflammation and their impact on the composition of the colonic microbiota is not well understood. Using a model of inflammation-induced colorectal cancer, we found that Lactobacillus species are lost more quickly in wild-type (WT) mice than TLR6-deficient mice resulting in overall differences in bacterial composition. Despite the longer retention of Lactobacillus, the TLR6-deficient mice presented with more tumors and a worse overall outcome. Restoration of the lost Lactobacillus species suppressed inflammation, reduced tumor number, and prevented change in the abundance of Proteobacteria only when given to WT mice, indicating the effect of these Lactobacillus are TLR6 dependent. We found that the TLR6-dependent effects of Lactobacillus could be dissociated from one another via the involvement of IL10, which was necessary to dampen the inflammatory microenvironment, but had no effect on bacterial composition. Altogether, these data suggest that innate immune signals can shape the composition of the microbiota under chronic inflammatory conditions, bias the cytokine milieu of the tissue microenvironment, and influence the response to microbiota-associated therapies.

Wheel running behaviour in group-housed female mice indicates disturbed wellbeing due to DSS colitis

Voluntary wheel running (VWR) behaviour is a sensitive indicator of disturbed wellbeing and used for the assessment of individual experimental severity levels in laboratory mice. However, monitoring individual VWR performance usually requires single housing, which itself might have a negative effect on wellbeing. In consideration of the 3Rs principle, VWR behaviour was evaluated under group-housing conditions. To test the applicability for severity assessment, this readout was evaluated in a dextran sodium sulphate (DSS) induced colitis model. For continuous monitoring, an automated system with integrated radio-frequency identification technology was used, enabling detection of individual VWR. After a 14-day adaptation period mice demonstrated a stable running performance. Analysis during DSS treatment in combination with repeated facial vein phlebotomy and faecal sampling procedure resulted in significantly reduced VWR behaviour during the course of colitis and increased VWR during disease recovery. Mice submitted to phlebotomy and faecal sampling but no DSS treatment showed less reduced VWR but a longer-lasting recovery. Application of a cluster model discriminating individual severity levels based on VWR and body weight data revealed the highest severity level in most of the DSS-treated mice on day 7, but a considerable number of control mice also showed elevated severity levels due to sampling procedures alone. In summary, VWR sensitively indicated the course of DSS colitis severity and the impact of sample collection. Therefore, monitoring of VWR is a suitable method for the detection of disturbed wellbeing due to DSS colitis and sampling procedure in group-housed female laboratory mice.

Light-entrained and brain-tuned circadian circuits regulate ILC3s and gut homeostasis

Group 3 innate lymphoid cells (ILC3s) are major regulators of inflammation, infection, microbiota composition and metabolism1. ILC3s and neuronal cells have been shown to interact at discrete mucosal locations to steer mucosal defence2,3. Nevertheless, it is unclear whether neuroimmune circuits operate at an organismal level, integrating extrinsic environmental signals to orchestrate ILC3 responses. Here we show that light-entrained and brain-tuned circadian circuits regulate enteric ILC3s, intestinal homeostasis, gut defence and host lipid metabolism in mice. We found that enteric ILC3s display circadian expression of clock genes and ILC3-related transcription factors. ILC3-autonomous ablation of the circadian regulator Arntl led to disrupted gut ILC3 homeostasis, impaired epithelial reactivity, a deregulated microbiome, increased susceptibility to bowel infection and disrupted lipid metabolism. Loss of ILC3-intrinsic Arntl shaped the gut 'postcode receptors' of ILC3s. Strikingly, light-dark cycles, feeding rhythms and microbial cues differentially regulated ILC3 clocks, with light signals being the major entraining cues of ILC3s. Accordingly, surgically or genetically induced deregulation of brain rhythmicity led to disrupted circadian ILC3 oscillations, a deregulated microbiome and altered lipid metabolism. Our work reveals a circadian circuitry that translates environmental light cues into enteric ILC3s, shaping intestinal health, metabolism and organismal homeostasis.

A protocol for making and sectioning multiple embedded Swiss-rolls in a gelatin matrix

The appropriate methodological approach for intestinal preparation enables researchers to create representative histological and immunostaining images which validate their biochemical data. The Swiss-roll technique was first introduced by Reilly and Kirsner in 1965. Later, Moolenbeek and Ruitenberg described a detailed procedure to longitudinally study the rodent intestine in 1981 [1]. In this publication, our slightly different approach for co-embedding four different Swiss-rolls in a gelatin block provides a full-length overview of cross-sectional colons on a single slide. This protocol allows for longitudinal histologic examination of multiple tissue samples on a single slide simultaneously. In this method, antigenicity is retained for immunohistology. In addition, the accessibility of samples during the prolonged hardening time required of the gelatin matrix allows the tissue samples to be adjusted/re-adjusted to provide the desired orientation and spatial arrangement for ideal cross sections with similar planes of section and optimum space utilization for slide mounting. Although not the focus of this protocol, the room temperature stability of the gelatin matrix and the ability to contain numerous tissue samples in a block allows the flexibility of performing thicker sections for free-floating tissue staining and ease of mounting a single gelatin sheet rather than individual tissue sections. This is a convenient approach for allowing precise preparation of multi-tissue blocks and simultaneous sectioning, staining, and slide mounting of tissue for subsequent comparisons.

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A single gelatin block is prepared by simultaneously embedding at least four different intestinal Swiss-rolls.

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The tissue orientation can be adjusted for each sample as desired which facilitates the comparison of different colon samples on a single gelatin section.

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The gelatin sections containing tissue samples are stable at least overnight at room temperature for staining.

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.

Helicase-like transcription factor (Hltf) gene-deletion promotes oxidative phosphorylation (OXPHOS) in colorectal tumors of AOM/DSS-treated mice

The helicase-like transcription factor (HLTF) gene-a tumor suppressor in human colorectal cancer (CRC)-is regulated by alternative splicing and promoter hypermethylation. In this study, we used the AOM/DSS-induced mouse model to show Hltf-deletion caused poor survival concomitant with increased tumor multiplicity, and dramatically shifted the topographic distribution of lesions into the rectum. Differential isoform expression analysis revealed both the truncated isoform that lacks a DNA-repair domain and the full length isoform capable of DNA damage repair are present during adenocarcinoma formation in controls. iPathwayGuide identified 51 dynamically regulated genes of 10,967 total genes with measured expression. Oxidative Phosphorylation (Kegg: 00190), the top biological pathway perturbed by Hltf-deletion, resulted from increased transcription of Atp5e, Cox7c, Uqcr11, Ndufa4 and Ndufb6 genes, concomitant with increased endogenous levels of ATP (p = 0.0062). Upregulation of gene expression, as validated with qRT-PCR, accompanied a stable mtDNA/nDNA ratio. This is the first study to show Hltf-deletion in an inflammation-associated CRC model elevates mitochondrial bioenergetics.

Complex Bacterial Consortia Reprogram the Colitogenic Activity of Enterococcus faecalis in a Gnotobiotic Mouse Model of Chronic, Immune-Mediated Colitis

Inflammatory bowel diseases (IBD) are associated with compositional and functional changes of the intestinal microbiota, but specific contributions of individual bacteria to chronic intestinal inflammation remain unclear. Enterococcus faecalis is a resident member of the human intestinal core microbiota that has been linked to the pathogenesis of IBD and induces chronic colitis in susceptible monoassociated IL-10-deficient (IL-10^−/−) mice. In this study, we characterized the colitogenic activity of E. faecalis as part of a simplified human microbial consortium based on seven enteric bacterial strains (SIHUMI). RNA sequencing analysis of E. faecalis isolated from monoassociated wild type and IL-10^−/− mice identified 408 genes including 14 genes of the ethanolamine utilization (eut) locus that were significantly up-regulated in response to inflammation. Despite considerable up-regulation of eut genes, deletion of ethanolamine utilization (ΔeutVW) had no impact on E. faecalis colitogenic activity in monoassociated IL-10^−/− mice. However, replacement of the E. faecalis wild type bacteria by a ΔeutVW mutant in SIHUMI-colonized IL-10^−/− mice resulted in exacerbated colitis, suggesting protective functions of E. faecalis ethanolamine utilization in complex bacterial communities. To better understand E. faecalis gene response in the presence of other microbes, we purified wild type E. faecalis cells from the colon content of SIHUMI-colonized wild type and IL-10^−/− mice using immuno-magnetic separation and performed RNA sequencing. Transcriptional profiling revealed that the bacterial environment reprograms E. faecalis gene expression in response to inflammation, with the majority of differentially expressed genes not being shared between monocolonized and SIHUMI conditions. While in E. faecalis monoassociation a general bacterial stress response could be observed, expression of E. faecalis genes in SIHUMI-colonized mice was characterized by up-regulation of genes involved in growth and replication. Interestingly, in mice colonized with SIHUMI lacking E. faecalis enhanced inflammation was observed in comparison to SIHUMI-colonized mice, supporting the hypothesis that E. faecalis ethanolamine metabolism protects against colitis in complex consortia. In conclusion, this study demonstrates that complex bacterial consortia interactions reprogram the gene expression profile and colitogenic activity of the opportunistic pathogen E. faecalis toward a protective function.

Vitamin D supplementation partially affects colonic changes in dextran sulfate sodium-induced colitis obese mice but not lean mice

Inflammatory bowel disease (IBD) often accompanies vitamin D deficiency, and vitamin D supplementation ameliorates IBD symptoms in animal models and humans. Because altered vitamin D metabolism has been reported in obesity, we hypothesized that the effects of vitamin D on the development of IBD would be different between obese and control mice. Five-week-old male C57BL/6N mice were divided into 4 groups and fed a diet differing in fat content (10% or 45%, normal diet [ND] or high-fat diet [HFD]) and vitamin D content (1000 or 10 000 IU/kg of diet, vDC or vDS) for 14 weeks. At week 13, colitis was induced by administration of 2% dextran sodium sulfate for 7 days. Histology score tended to be lower in the HFD-vDS group than HFD-vDC group, but there was no effect of vitamin D on the ND group. Colonic Cldn1 and Cyp27b1 mRNA levels were higher in the HFD-vDS than HFD-vDC group, but these effects of vitamin D were not observed in the ND group. The serum 25-hydroxy vitamin D levels were negatively correlated with the histology score in the HFD group but not in the ND group. Overall, these results suggest that vitamin D supplementation partially prevents the histological damage of the colon in obese mice but not in control mice. This effect might be mediated by increased colonic Cyp27b1 levels, leading to upregulation of local 1,25-dihydroxy vitamin D production.

A Macromolecular Janus Kinase (JAK) Inhibitor Prodrug Effectively Ameliorates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice

BACKGROUND

Tofacitinib (Tofa) has been approved for moderately to severely active ulcerative colitis (UC). To improve its therapeutic efficacy and limit dose-dependent toxicity, we developed a macromolecular prodrug of Tofa (P-Tofa). If the prodrug design improves the potency and duration of Tofa therapy, it would widen its therapeutic window, potentially leading to improved safety and better clinical management of UC.

METHODS

P-Tofa was synthesized by conjugating Tofa to N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer via a cleavable carbamate linker. DSS-induced UC mouse model were treated with Tofa (daily oral gavage, from day 8), P-Tofa (single intravenous administration on day 8, dose equivalent to Tofa treatment) and saline. Healthy mice were used as a positive control. The therapeutic efficacy was evaluated using disease activity index (DAI), endoscopic score and end-point histology. The optical imaging, immunohistochemistry and flow cytometry were used to understand P-Tofa's working mechanism.

RESULTS

DAI results suggested that a single dose P-Tofa treatment was more efficacious than dose equivalent daily Tofa treatment. Endoscopic evaluation and histology analyses confirmed that while both P-Tofa and Tofa protected the colon, P-Tofa treated group was observed with better colon integrity with less tissue damage. Optical imaging, flow cytometry and immunohistochemistry results showed that P-Tofa passively targeted the inflamed colon and being retained via cellular sequestration.

CONCLUSIONS

Single intravenous administration of P-Tofa was more effective than dose equivalent daily oral Tofa gavage in ameliorating DSS-induced colitis. This observed superior therapeutic efficacy may be attributed to P-Tofa's passive targeting to and retention by the inflamed colon.

Abscisic acid stimulates the release of insulin and of GLP-1 in the rat perfused pancreas and intestine

AIMS

Previous results indicate that nanomolar concentrations of abscisic acid (ABA) stimulate insulin release from β-pancreatic cells in vitro and that oral ABA at 50 mg/kg increases plasma GLP-1 in the fasted rat. The aim of this study was to test the effect of ABA on the perfused rat pancreas and intestine, to verify the insulin- and incretin-releasing actions of ABA in controlled physiological models.

MATERIALS AND METHODS

Rat pancreas and small intestine were perfused with solutions containing ABA at high-micromolar concentrations, or control secretagogues. Insulin and GLP-1 concentrations in the venous effluent were analysed by radioimmunoassay, and ABA levels were determined by ELISA.

RESULTS

High micromolar concentrations of ABA induced GLP-1 secretion from the proximal half of the small intestine and insulin secretion from pancreas. GLP-1 stimulated ABA secretion from pancreas in a biphasic manner. Notably, a positive correlation was found between the ABA area under the curve (AUC) and the insulin AUC upon GLP-1 administration.

CONCLUSION

Our results indicate the existence of a cross talk between GLP-1 and ABA, whereby ABA stimulates GLP-1 secretion, and vice versa. Release of ABA could be considered as a new promising molecule in the strategy of type 2 diabetes treatment and as a new endogenous hormone in the regulation of glycaemia.

Osteopontin Protects Colonic Mucosa from Dextran Sodium Sulfate-Induced Acute Colitis in Mice by Regulating Junctional Distribution of Occludin

BACKGROUND

Osteopontin (OPN) has been reported to play an important role in intestinal mucosal protection. Although OPN may have positive effects on tight junctions, the exact relationship between OPN and tight junctions has yet to be elucidated.

AIMS

To investigate the role of OPN on tight junctions.

METHODS

We evaluated clinical signs and histopathology of acute colitis induced by dextran sodium sulfate (DSS) in OPN knockout and wild-type (WT) mice in vivo. Expression levels of occludin and zonula occludens-1 were examined using immunofluorescence. For in vitro analysis, an siRNA-mediated OPN-suppressed Caco-2 monolayer was used. Expression levels and patterns of occludin were analyzed by immunofluorescence, and transepithelial electrical resistance (TER) was measured to evaluate barrier function. Triton X-100 fractionation was used to analyze phosphorylated occludin associated with tight junctional localization.

RESULTS

OPN deficiency resulted in an elevated disease activity index, shortened colon length, and aggravated histological signs in mice with DSS-induced acute colitis compared to WT mice. OPN deficiency decreased occludin expression in the colonic mucosa. In Caco-2 monolayers, OPN suppression reduced junctional occludin and redistributed it into the intracellular compartment with decreased TER. Furthermore, western blot for occludin from Triton X-100 insoluble fraction revealed that OPN suppression reduced the phosphorylated form of occludin, which is actually distributed in the tight junction.

CONCLUSIONS

Our study showed that OPN is essential for maintaining the tight junction complex by allowing occludin to localize at tight junctions. This could constitute additional evidence that OPN plays a crucial role in intestinal mucosal protection.

Loss of RHBDF2 results in an early-onset spontaneous murine colitis

Inflammatory bowel disease (IBD) is a heterogeneous group of inflammation-mediated pathologies that include Crohn's disease and ulcerative colitis and primarily affects the colon and small intestine. Previous studies have shown that a disintegrin and metalloprotease (ADAM) 17, a membrane-bound sheddase, capable of cleaving the proinflammatory cytokine TNF and epidermal growth factor receptor ligands, plays a critical role in maintaining gut homeostasis and modulating intestinal inflammation during IBD. Rhomboid 5 homolog 2 (RHBDF2), a catalytically inactive member of the rhomboid family of intramembrane serine proteases, was recently identified as a crucial regulator of ADAM17. Here, we assessed the role of RHBDF2 in the development of colitis in the context of IL10 deficiency. Il10^-/- /Rhbdf2^-/- mice developed spontaneous colitis and experienced severe weight loss starting at 8 wk of age, without the need for exogenous triggers. Severity of disease pathology in Il10^-/- /Rhbdf2^-/- mice correlated with a dysbiotic gut microbiota and elevated Th1-associated immune responses with increased interferon gamma and IL2 production. In addition, Il10^-/- /Rhbdf2^-/- mice failed to maintain their epithelial cell homeostasis, although the intestinal epithelial barrier of Rhbdf2^-/- mice is intact and loss of Rhbdf2 did not significantly exacerbate sensitivity to dextran sulfate sodium-induced colitis, suggesting differences in the underlying disease pathway of intestinal inflammation in this model. Taken together, our results demonstrate a critical regulatory role for RHBDF2 in the maintenance of the unique homeostasis between intestinal microbiota and host immune responses in the gut that is dysregulated during the pathogenesis of IBD.

Enteric Murine Ganglionitis Induced by Autoimmune CD8 T Cells Mimics Human Gastrointestinal Dysmotility

Inflammatory bowel diseases frequently cause gastrointestinal dysmotility, suggesting that they may also affect the enteric nervous system. So far, the precise mechanisms that lead to gastrointestinal dysmotility in inflammatory bowel diseases have not been elucidated. To determine the effect of CD8 T cells on gastrointestinal motility, transgenic mice expressing ovalbumin on enteric neurons were generated. In these mice, adoptive transfer of ovalbumin-specific OT-I CD8 T cells induced severe enteric ganglionitis. CD8 T cells homed to submucosal and myenteric plexus neurons, 60% of which were lost, clinically resulting in severely impaired gastrointestinal transition. Anti-interferon-γ treatment rescued neurons by preventing their up-regulation of major histocompatibility complex class I antigen, thus preserving gut motility. These preclinical murine data translated well into human gastrointestinal dysmotility. In a series of 30 colonic biopsy specimens from patients with gastrointestinal dysmotility, CD8 T cell-mediated ganglionitis was detected that was followed by severe loss of enteric neurons (74.8%). Together, the preclinical and clinical data support the concept that autoimmune CD8 T cells play an important pathogenetic role in gastrointestinal dysmotility and may destroy enteric neurons.

Anticipation of food intake induces phosphorylation switch to regulate basolateral amino acid transporter LAT4 (SLC43A2) function

KEY POINTS

Amino acid absorption requires luminal uptake into and subsequent basolateral efflux out of epithelial cells, with the latter step being critical to regulate the intracellular concentration of the amino acids. The basolateral essential neutral amino acid uniporter LAT4 (SLC43A2) has been suggested to drive the net efflux of non-essential and cationic amino acids via parallel amino acid antiporters by recycling some of their substrates; its deletion has been shown to cause defective postnatal growth and death in mice. Here we test the regulatory function of LAT4 phosphorylation sites by mimicking their phosphorylated and dephosphorylated states in Xenopus laevis oocytes and show that dephosphorylation of S274 and phosphorylation of S297 increase LAT4 membrane localization and function. Using new phosphorylation site-specific antibodies, we observe changes in LAT4 phosphorylation in mouse small intestine that correspond to its upregulation at the expected feeding time. These results strongly suggest that LAT4 phosphorylation participates in the regulation of transepithelial amino acid absorption.

ABSTRACT

The essential amino acid uniporters LAT4 and TAT1 are located at the basolateral side of intestinal and kidney epithelial cells and their transport function has been suggested to control the transepithelial (re)absorption of neutral and possibly also cationic amino acids. Uniporter LAT4 selectively transports the branched chain amino acids leucine, isoleucine and valine, and additionally methionine and phenylalanine. Its deletion leads to a postnatal growth failure and early death in mice. Since LAT4 has been reported to be phosphorylated in vivo, we hypothesized that phosphorylation regulates its function. Using Xenopus laevis oocytes, we tested the impact of LAT4 phosphorylation at Ser274 and Ser297 by expressing mutant constructs mimicking phosphorylated and dephosphorylated states. We then investigated the in vivo regulation of LAT4 in mouse small intestine using new phosphorylation site-specific antibodies and a time-restricted diet. In Xenopus oocytes, mimicking non-phosphorylation of Ser274 led to an increase in affinity and apparent surface membrane localization of LAT4, stimulating its transport activity, while the same mutation of Ser297 decreased LAT4's apparent surface expression and transport rate. In wild-type mice, LAT4 phosphorylation on Ser274 was uniform at the beginning of the inactive phase (ZT0). In contrast, at the beginning of the active phase (ZT12), corresponding to the anticipated feeding time, Ser274 phosphorylation was decreased and restricted to relatively large patches of cells, while Ser297 phosphorylation was increased. We conclude that phosphorylation of small intestinal LAT4 is under food-entrained circadian control, leading presumably to an upregulation of LAT4 function at the anticipated feeding time.

A series of three cases of severe Clostridium difficile infection in Australia associated with a binary toxin producing clade 2 ribotype 251 strain

Three patients with severe Clostridium difficile infection (CDI) caused by an unusual strain of C. difficile, PCR ribotype (RT) 251, were identified in New South Wales, Australia. All cases presented with severe diarrhoea, two had multiple recurrences and one died following a colectomy. C. difficile RT251 strains were isolated by toxigenic culture. Genetic characterisation was performed using techniques including toxin gene profiling, PCR ribotyping, whole genome sequencing (WGS), in-silico multi-locus-sequence-typing (MLST) and core-genome single nucleotide variant (SNV) analyses. Antimicrobial susceptibility was determined using an agar incorporation method. In vitro toxin production was confirmed by Vero cell cytotoxicity assay and pathogenicity was assessed in a murine model of CDI. All RT251 isolates contained toxin A (tcdA), toxin B (tcdB) and binary toxin (cdtA and cdtB) genes. Core-genome analyses revealed the RT251 strains were clonal, with 0-5 SNVs between isolates. WGS and MLST clustered RT251 in the same evolutionary clade (clade 2) as RT027. Despite comparatively lower levels of in vitro toxin production, in the murine model RT251 infection resembled RT027 infection. Mice showed marked weight loss, severe disease within 48 h post-infection and death. All isolates were susceptible to metronidazole and vancomycin. Our observations suggest C. difficile RT251 causes severe disease and emphasise the importance of ongoing surveillance for new and emerging strains of C. difficile with enhanced virulence.

Exploratory Investigation of Intestinal Function and Bacterial Translocation After Focal Cerebral Ischemia in the Mouse

Background and Purpose: The gut communicates with the brain bidirectionally via neural, humoral and immune pathways. All these pathways are affected by acute brain lesions, such as stroke. Brain-gut communication may therefore impact on the overall outcome after CNS-injury. Until now, contradictory reports on intestinal function and translocation of gut bacteria after experimental stroke have been published. Accordingly, we aimed to specifically investigate the effects of transient focal cerebral ischemia on intestinal permeability, gut associated lymphoid tissue and bacterial translocation in an exploratory study using a well-characterized murine stroke model.

Methods: After 60 min of middle cerebral artery occlusion (MCAO) we assessed intestinal morphology (time points after surgery day 0, 3, 5, 14, 21) and tight junction protein expression (occludin and claudin-1 at day 1 and 3) in 12-week-old male C57Bl/6J mice. Lactulose/mannitol/sucralose test was performed to assess intestinal permeability 24–72 h after surgery. To investigate the influence of cerebral ischemia on the local immune system of the gut, main immune cell populations in Peyer's patches (PP) were quantified by flow cytometry. Finally, we evaluated bacterial translocation to extraintestinal organs 24 and 72 h after MCAO by microbiological culture and fluorescence in situ hybridization targeting bacterial 16S rRNA.

Results: Transient MCAO decreased claudin-1 expression in the ileum but not in the colon. Intestinal morphology (assessed by light microscopy) and permeability did not change measurably after MCAO. After MCAO, animals had significantly fewer B cells in PP compared to naïve mice.

Conclusions: In a murine model of stroke, which leads to large brain infarctions in the middle cerebral artery territory, we did not find evidence for overt alterations neither in gut morphology, barrier proteins and permeability nor presence of intestinal bacterial translocation.

Plasmacytoid Dendritic Cells Are Largely Dispensable for the Pathogenesis of Experimental Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory condition caused by an aberrant immune response to microbial components of the gastrointestinal tract. Plasmacytoid dendritic cells (pDCs) are innate immune cells specialized in the production of type I interferons and were recently implicated in the pathogenesis of autoimmune disorders such as lupus and scleroderma. While pDCs were shown to infiltrate intestinal mucosa of IBD patients and proposed to participate in intestinal inflammation, their net contribution to the disease remains unclear. We addressed this question by targeting the pDC-specific transcription factor TCF4 (E2-2) in experimental IBD caused by deficiency of Wiskott-Aldrich syndrome protein (WASP) or of interleukin-10 (IL-10). Monoallelic Tcf4 deletion, which was previously shown to abrogate experimental lupus, did not affect autoimmunity manifestations or colitis in WASP-deficient animals. Furthermore, conditional biallelic Tcf4 targeting resulted in a near-complete pDC ablation, yet had no effect on the development of colitis in IL-10-deficient mice. Our results suggest that, in contrast to other inflammatory and autoimmune diseases, pDCs do not play a major role in the pathogenesis of intestinal inflammation during IBD.

Running in the wheel: Defining individual severity levels in mice

The fine-scale grading of the severity experienced by animals used in research constitutes a key element of the 3Rs (replace, reduce, and refine) principles and a legal requirement in the European Union Directive 2010/63/EU. Particularly, the exact assessment of all signs of pain, suffering, and distress experienced by laboratory animals represents a prerequisite to develop refinement strategies. However, minimal and noninvasive methods for an evidence-based severity assessment are scarce. Therefore, we investigated whether voluntary wheel running (VWR) provides an observer-independent behaviour-centred approach to grade severity experienced by C57BL/6J mice undergoing various treatments. In a mouse model of chemically induced acute colitis, VWR behaviour was directly related to colitis severity, whereas clinical scoring did not sensitively reflect severity but rather indicated marginal signs of compromised welfare. Unsupervised k-means algorithm–based cluster analysis of body weight and VWR data enabled the discrimination of cluster borders and distinct levels of severity. The validity of the cluster analysis was affirmed in a mouse model of acute restraint stress. This method was also applicable to uncover and grade the impact of serial blood sampling on the animal’s welfare, underlined by increased histological scores in the colitis model. To reflect the entirety of severity in a multidimensional model, the presented approach may have to be calibrated and validated in other animal models requiring the integration of further parameters. In this experimental set up, however, the automated assessment of an emotional/motivational driven behaviour and subsequent integration of the data into a mathematical model enabled unbiased individual severity grading in laboratory mice, thereby providing an essential contribution to the 3Rs principles.

Animal-based biomedical research is often accompanied by experience of discomfort or pain by the animal. Recognition of disturbed animal welfare is mandatory, and the classification and assessment of its severity is a crucial part of the legislative framework in the European Union (EU). In the present study, we analysed voluntary wheel running (VWR) behaviour as a measure of compromised welfare in a mouse colitis model. Unsupervised mathematical clustering of clinical and VWR data enabled us to allocate and classify severity levels. This cluster model was verified using VWR data from a restraint stress model and allowed us to uncover the impact of routine experimental procedures on these mice. We propose that clustering of VWR behaviour provides a useful method for assessing the severity level of experimental procedures conducted on mice.

Inhibitory effects of pentoxifylline on inflammation-related tumorigenesis in rat colon

Chronic inflammation in the colorectum increases the risk of colorectal cancer development. Pentoxifylline, a medicine used for improving the circulation, has been reported to inhibit TNF-α production and to ameliorate inflammatory bowel disease and non-alcoholic steatohepatitis. In this study, we investigated the effects of pentoxifylline on inflammation-related colon tumorigenesis in a rodent model using Kyoto APC delta rats, which have APC mutation and are susceptible to colon carcinogenesis. Male Kyoto APC delta rats were treated with azoxymethane and dextran sodium sulfate, and were subsequently administered water, with or without pentoxifylline. At the end of the experiment, the development of colorectal tumor was significantly inhibited in the pentoxifylline group. The pentoxifylline treatment also lowered the levels of oxidative stress markers and mRNAs of pro-inflammatory cytokines, including TNF-α and IL-6, in the colon mucosa. The PCNA labeling index and the inflammation score were also decreased in the colon of rats in the pentoxifylline -treated group. We also used an endoscopy to observe the tumor progression and inflammation in the colon of rats, revealing that inflammation grade was significantly lower in pentoxifylline-treated group at several points during the experiment. These findings suggest that pentoxifylline treatment might be useful for chemoprevention of inflammation-related colon cancer.

T1R2 receptor-mediated glucose sensing in the upper intestine potentiates glucose absorption through activation of local regulatory pathways

Objective

Beyond the taste buds, sweet taste receptors (STRs; T1R2/T1R3) are also expressed on enteroendocrine cells, where they regulate gut peptide secretion but their regulatory function within the intestine is largely unknown.

Methods

Using T1R2-knock out (KO) mice we evaluated the role of STRs in the regulation of glucose absorption in vivo and in intact intestinal preparations ex vivo.

Results

STR signaling enhances the rate of intestinal glucose absorption specifically in response to the ingestion of a glucose-rich meal. These effects were mediated specifically by the regulation of GLUT2 transporter trafficking to the apical membrane of enterocytes. GLUT2 translocation and glucose transport was dependent and specific to glucagon-like peptide 2 (GLP-2) secretion and subsequent intestinal neuronal activation. Finally, high-sucrose feeding in wild-type mice induced rapid downregulation of STRs in the gut, leading to reduced glucose absorption.

Conclusions

Our studies demonstrate that STRs have evolved to modulate glucose absorption via the regulation of its transport and to prevent the development of exacerbated hyperglycemia due to the ingestion of high levels of sugars.

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The intestinal T1R2 receptor enhances glucose absorption in vivo and ex vivo.

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Pharmacological inhibition of STRs reduces glucose flux in human intestinal preparations.

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T1R2 regulates glucose absorption dependent on GLUT2 activity in enterocytes.

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GLP-2 mediates the effects of T1R2 signaling through activation of enteric neurons.

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High sucrose diet rapidly downregulates STRs leading to reduced glucose absorption.

S100A4 promotes colon inflammation and colitis-associated colon tumorigenesis

S100A4 plays important roles in tumor development and metastasis, but its role in regulating inflammation and colitis-associated tumorigenesis has not been well characterized. Here, we report that S100A4 expression was increased in azoxymethane (AOM) and dextran sulfate sodium (DSS) induced colorectal cancer (CRC) in mice. After AOM/DSS treatment, both S100A4-TK mice with the selective depletion of S100A4-expressing cells and S100A4-deficient (S100A4^−/−) mice developed fewer and smaller tumors than wild-type (WT) control littermates. Furthermore, S100A4^−/− mice were resistant to DSS-induced colitis, reduced infiltration of macrophages, and the diminished production of proinflammatory cytokines. Further studies revealed that reduced colon inflammation and colorectal tumor development in S100A4^−/− mice were partly due to the dampening of nuclear factor (NF)-κB activation in macrophages. Furthermore, the administration of a neutralizing S100A4 antibody to WT mice significantly decreased AOM/DSS-induced colon inflammation and tumorigenesis. These results indicate that S100A4 amplifies an inflammatory microenvironment that promotes colon tumorigenesis and provides a promising therapeutic strategy for treatment of inflammatory bowel disease and prevention of colitis-associated colorectal carcinogenesis.

Pre-clinical and translational pharmacology of a human interleukin-22 IgG fusion protein for potential treatment of infectious or inflammatory diseases

Interleukin (IL)-22 plays protective roles in infections and in inflammatory diseases that have been linked to its meditation of innate immunity via multiple mechanisms. IL-22 binds specifically to its heterodimeric receptor, which is expressed on a variety of epithelial tissues. UTTR1147A is a recombinant fusion protein that links the human cytokine IL-22 with the Fc portion of human immunoglobulin (Ig) G4. Here, we report extensive in vitro and in vivo nonclinical studies that were conducted to characterize the pharmacological activity of UTTR1147A. The in vitro activity and potency of UTTR1147A were analyzed using primary human hepatocytes and human colonic epithelial cell lines. Assessment of in vivo efficacy was performed in a mouse colitis model and by measuring relevant pharmacodynamic biomarkers, including antimicrobial peptides REG3A/β, serum amyloid protein A (SAA) and lipopolysaccharide binding protein (LBP). The pharmacokinetic and pharmacodynamic characteristics of UTTR1147A were assessed in healthy mice, rats and cynomolgus monkeys. UTTR1147A induced STAT3 activation through binding to IL-22 receptor expressed in primary human hepatocytes and human colon cell lines. In both, activation occurred in a concentration-dependent manner with similar potencies. In the mouse colitis model, murine IL-22Fc- (muIL-22Fc) treated groups at doses of 1.25 μg and above had statistically lower average histologic colitis scores compared to the control treated group. Administration of muIL-22Fc or UTTR1147A was associated with a dose-dependent induction of PD markers REG3β and SAA in rodents as well as REG3A, SAA and LBP in cynomolgus monkeys. The combined data confirm pharmacological activity of IL-22Fc and support potential regenerative and protective mechanisms in epithelial tissues.

Tuft cells: Distribution and connections with nerves and endocrine cells in mouse intestine

Tuft cells are gastrointestinal (GI) sensory cells recognized by their characteristic shape and their microvilli "tuft". Aims of the present study were to elucidate their regional distribution and spatial connections with satiety associated endocrine cells and nerve fibers throughout the intestinal tract. C57BL/6 J mice were used in the experiments. The small intestine was divided into five segments, and the large intestine was kept undivided. The segments were coiled into "Swiss rolls". Numbers and topographic distribution of tuft cells and possible contacts with endocrine cells and nerve fibers were estimated in the different segments, using immunocytochemistry. Tuft cells were found throughout the intestines; the highest number was in proximal small intestine. Five percent of tuft cells were found in close proximity to cholecystokinin-immunoreactive (IR) endocrine cells and up to 10% were in contact with peptide YY- and glucagon-like peptide-1-IR endocrine cells. Sixty percent of tuft cells in the small intestine and 40% in the large intestine were found in contact with nerve fibers. Calcitonin gene-related peptide-IR fibers constituted one-third of the fiber-contacts in the small intestine and two-thirds in the large intestine. These observations highlight the possibility of tuft cells as modulators of GI activities in response to luminal signaling.

Milk Fat Globules Hamper Adhesion of Enterohemorrhagic Escherichia coli to Enterocytes: In Vitro and in Vivo Evidence

Enterohemorrhagic Escherichia coli (EHEC; E. coli) are food-borne agents associated with gastroenteritis, enterocolitis, bloody diarrhea and the hemolytic-uremic syndrome (HUS). Bovine milk glycans have been shown to contain oligosaccharides which are similar to host epithelial cell receptors and can therefore prevent bacterial adhesion. This study aimed to describe interactions between EHEC O157:H7 EDL933 and O26:H11 21765 and milk fat globules (MFGs) in raw milk and raw milk cheese, and the impact of MFGs on EHEC strains adhesion to the intestinal tract in vitro and in vivo. Both EHEC serotypes clearly associated with native bovine MFGs and significantly limited their adhesion to a co-culture of intestinal cells. The presence of MFGs in raw milk cheese had two effects on the adhesion of both EHEC serotypes to the intestinal tracts of streptomycin-treated mice. First, it delayed and reduced EHEC excretion in mouse feces for both strains. Second, the prime implantation site for both EHEC strains was 6 cm more proximal in the intestinal tracts of mice fed with contaminated cheese containing less than 5% of fat than in those fed with contaminated cheese containing 40% of fat. Feeding mice with 40% fat cheese reduced the intestinal surface contaminated with EHEC and may therefore decrease severity of illness.

A new species of Cystoisospora Frenkel, 1977 (Apicomplexa: Sarcocystidae) from Oecomys mamorae Thomas (Rodentia: Cricetidae) in the Brazilian Pantanal

Despite the great diversity of coccidians, to our knowledge, no coccidian infections have been described in Oecomys spp. In this context, we examined Oecomys mamorae Thomas (Rodentia: Cricetidae) from the Brazilian Pantanal for infections with enteric coccidia. Nine individuals were sampled, and one was found to be infected. The oöcysts were recovered through centrifugal flotation in sugar solution. Using morphological and morphometric features, we described a new species of Cystoisospora Frenkel, 1977. Sporulated oöcysts were ovoidal 20.0-29.1 × 16.4-23.2 (26.7 × 21.2) µm and contained two sporocysts, 12.9-19.1 × 9.4-13.9 (16.4 × 12.4) µm, each with four banana-shaped sporozoites. Polar granule and oöcyst residuum were both absent. We documented the developmental forms in the small intestine and described the histopathological lesions in the enteric tract. Our results indicate that the prevalence of Cystoisospora mamorae n. sp. in O. mamorae is low, and tissue damage in the enteric tract is mild, even in the presence of coccidian developmental stages.

PLK1 has tumor-suppressive potential in APC-truncated colon cancer cells

The spindle assembly checkpoint (SAC) acts as a molecular safeguard in ensuring faithful chromosome transmission during mitosis, which is regulated by a complex interplay between phosphatases and kinases including PLK1. Adenomatous polyposis coli (APC) germline mutations cause aneuploidy and are responsible for familial adenomatous polyposis (FAP). Here we study the role of PLK1 in colon cancer cells with chromosomal instability promoted by APC truncation (APC-ΔC). The expression of APC-ΔC in colon cells reduces the accumulation of mitotic cells upon PLK1 inhibition, accelerates mitotic exit and increases the survival of cells with enhanced chromosomal abnormalities. The inhibition of PLK1 in mitotic, APC-∆C-expressing cells reduces the kinetochore levels of Aurora B and hampers the recruitment of SAC component suggesting a compromised mitotic checkpoint. Furthermore, Plk1 inhibition (RNAi, pharmacological compounds) promotes the development of adenomatous polyps in two independent Apc Min/+ mouse models. High PLK1 expression increases the survival of colon cancer patients expressing a truncated APC significantly.

ADAM17 is required for EGF-R-induced intestinal tumors via IL-6 trans-signaling

Schmidt et al. show that loss of the membrane-bound metalloprotease ADAM17 led to impaired intestinal cancer development in the murine APC^min/+ model, which also depended on IL-6 trans-signaling via the soluble IL-6R and could be blocked by the specific IL-6 trans-signaling inhibitor sgp130Fc.

Colorectal cancer is treated with antibodies blocking epidermal growth factor receptor (EGF-R), but therapeutic success is limited. EGF-R is stimulated by soluble ligands, which are derived from transmembrane precursors by ADAM17-mediated proteolytic cleavage. In mouse intestinal cancer models in the absence of ADAM17, tumorigenesis was almost completely inhibited, and the few remaining tumors were of low-grade dysplasia. RNA sequencing analysis demonstrated down-regulation of STAT3 and Wnt pathway components. Because EGF-R on myeloid cells, but not on intestinal epithelial cells, is required for intestinal cancer and because IL-6 is induced via EGF-R stimulation, we analyzed the role of IL-6 signaling. Tumor formation was equally impaired in IL-6^−/− mice and sgp130Fc transgenic mice, in which only trans-signaling via soluble IL-6R is abrogated. ADAM17 is needed for EGF-R–mediated induction of IL-6 synthesis, which via IL-6 trans-signaling induces β-catenin–dependent tumorigenesis. Our data reveal the possibility of a novel strategy for treatment of colorectal cancer that could circumvent intrinsic and acquired resistance to EGF-R blockade.

Mebendazole and a non-steroidal anti-inflammatory combine to reduce tumor initiation in a colon cancer preclinical model

Inheritance of a gene mutation leads to the initiation of 5 to 10% of most cancers, including colon cancer cases. We developed a chemoprevention strategy using a novel combination of the non-steroidal anti-inflammatory (NSAID) sulindac plus the anthelminthic benzimidazole, mebendazole. This oral drug combination was effective in the Apc^Min/+ mouse model of Familial Adenomatous Polyposis (FAP). Treatment with 35 mg/kg daily mebendazole reduced the number of intestinal adenomas by 56% (P = 0.0002), 160 ppm sulindac by 74% (P < 0.0001), and the combination by 90% (P < 0.0001). The combination significantly reduced microadenomas, polyp number and size in both the small intestines and colon when compared to untreated controls or sulindac alone. Mebendazole as a single agent decreased COX2 expression, blood vessel formation, VEGFR2 phosphorylation, and worked synergistically with sulindac to reduce overexpression of MYC, BCL2, and various pro-inflammatory cytokines. Given the low toxicity of mebendazole, these preclinical findings support the consideration of clinical trials for high risk cancer patients using mebendazole either alone or in combination. The findings have implications for populations with moderate and above risk for developing cancer.

Radiosensitization In Vivo by Histone Deacetylase Inhibition with No Increase in Early Normal Tissue Radiation Toxicity

As the population ages, more elderly patients require radiotherapy-based treatment for their pelvic malignancies, including muscle-invasive bladder cancer, as they are unfit for major surgery. Therefore, there is an urgent need to find radiosensitizing agents minimally toxic to normal tissues, including bowel and bladder, for such patients. We developed methods to determine normal tissue toxicity severity in intestine and bladder in vivo, using novel radiotherapy techniques on a small animal radiation research platform (SARRP). The effects of panobinostat on in vivo tumor growth delay were evaluated using subcutaneous xenografts in athymic nude mice. Panobinostat concentration levels in xenografts, plasma, and normal tissues were measured in CD1-nude mice. CD1-nude mice were treated with drug/irradiation combinations to assess acute normal tissue effects in small intestine using the intestinal crypt assay, and later effects in small and large intestine at 11 weeks by stool assessment and at 12 weeks by histologic examination. In vitro effects of panobinostat were assessed by qPCR and of panobinostat, TMP195, and mocetinostat by clonogenic assay, and Western blot analysis. Panobinostat resulted in growth delay in RT112 bladder cancer xenografts but did not significantly increase acute (3.75 days) or 12 weeks' normal tissue radiation toxicity. Radiosensitization by panobinostat was effective in hypoxic bladder cancer cells and associated with class I HDAC inhibition, and protein downregulation of HDAC2 and MRE11. Pan-HDAC inhibition is a promising strategy for radiosensitization, but more selective agents may be more useful radiosensitizers clinically, resulting in fewer systemic side effects. Mol Cancer Ther; 17(2); 381-92. ©2017 AACRSee all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology."

A Rodent Model of Anxiety: The Effect of Perinatal Immune Challenges on Gastrointestinal Inflammation and Integrity

OBJECTIVES

Gastrointestinal (GI) inflammation and GI integrity deficits are common comorbidities of neuropsychiatric disorders. Ongoing research suggests that these aberrations may be contributing to heightened immune signals that have the potential to disrupt neuronal homeostasis and exacerbate behavioural deficits. The current study aimed to determine whether the well-characterized animal model of neuropsychopathology, the maternal immune activation (MIA) model, produced GI inflammation and integrity disruptions in association with anxiety-like behaviour.

METHODS

Pregnant Wistar rats were exposed to the viral mimetic polyriboinosinic:polyribocytidilic acid (polyI:C) on gestational days (GD) 10 and 19. Evidence of ANS activation, GI inflammation, and GI barrier integrity was assessed in both neonatal (postnatal day, P7) and adult (P84) offspring. Anxiety-like behaviour was assessed at P100.

RESULTS

Neonatal MIA offspring exhibited an altered intestinal inflammatory profile and evidence of an increase in lymphoid aggregates. MIA neonates also displayed disruptions to GI barrier tight junction protein mRNA. In addition, adult MIA offspring exhibited an increase in anxiety-like behaviours.

CONCLUSION

These results indicate that the MIA rat model, which is well documented to produce behavioural, neurochemical, and neuroanatomical abnormalities, also produces GI inflammation and integrity disruptions. We suggest that this model may be a useful tool to elucidate biological pathways associated with neuropsychiatric disorders.

Intestinally-restricted Janus Kinase inhibition: a potential approach to maximize the therapeutic index in inflammatory bowel disease therapy

Background

An unmet need remains for safe and effective treatments to induce and maintain remission in inflammatory bowel disease (IBD) patients. The Janus kinase (JAK) inhibitor, tofacitinib, has demonstrated robust efficacy in ulcerative colitis patients although, like other systemic immunosuppressants, there may be safety concerns associated with its use. This preclinical study evaluated whether modulating intestinal inflammation via local JAK inhibition can provide efficacy without systemic immunosuppression.

Methods

The influence of tofacitinib, dosed orally or intracecally, on oxazolone-induced colitis, oxazolone or interferon-γ (IFNγ)-induced elevation of colonic phosphorylated signal transducer and activator of transcription1 (pSTAT1) levels, and basal splenic natural killer (NK) cell counts was investigated in mice.

Results

Tofacitinib, dosed orally or intracecally, inhibited, with similar efficacy, oxazolone-induced colitis, represented by improvements in the disease activity index and its sub-scores (body weight, stool consistency and blood content). Intracecal dosing of tofacitinib resulted in a higher colon:plasma drug exposure ratio compared to oral dosing. At equieffective oral and intracecal doses, colonic levels of tofacitinib were similar, while the plasma levels for the latter were markedly lower, consistent with a lack of effect on splenic NK cell counts. Tofacitinib, dosed orally, intracecally, or applied to the colonic lumen in vitro, produced dose-dependent, and maximal inhibition of oxazolone or IFNγ-induced STAT1 phosphorylation in the colon.

Conclusions

Localized colonic JAK inhibition, by intracecal delivery of tofacitinib, provides colonic target engagement and efficacy in a mouse colitis model at doses which do not impact splenic NK cell counts. Intestinal targeting of JAK may permit separation of local anti-inflammatory activity from systemic immunosuppression, and thus provide a larger therapeutic index compared to systemic JAK inhibitors.

Oral Exposure to Paraquat Triggers Earlier Expression of Phosphorylated α-Synuclein in the Enteric Nervous System of A53T Mutant Human α-Synuclein Transgenic Mice

The misfolded α-synuclein protein, phosphorylated at serine 129 (pSer129 α-syn), is the hallmark of Parkinson disease (PD). Detected also in the enteric nervous system (ENS), it supports the recent theory that PD could start in the gut, rather than the brain. In a previous study, using a transgenic mouse model of human synucleinopathies expressing the A53T mutant α-synuclein (TgM83), in which a neurodegenerative process associated with α-synuclein occurs spontaneously in the brain, we have shown earlier onset of pSer129 α-syn in the ENS. Here, we used this model to study the impact of paraquat (PQ) a neurotoxic herbicide incriminated in PD in agricultural workers) on the enteric pSer129 α-syn expression in young mice. Orally delivered in the drinking water at 10 mg/kg/day for 6–8 weeks, the impact of PQ was measured in a time-dependent manner on weight, locomotor abilities, pSer129 α-syn, and glial fibrillary acidic protein (GFAP) expression levels in the ENS. Remarkably, pSer129 α-syn was detected in ENS earlier under PQ oral exposure and enteric GFAP expression was also increased. These findings bring additional support to the theory that neurotoxic agents such as PQ initiate idiopathic PD after oral delivery.

Epicutaneous Tolerance Induction to a Bystander Antigen Abrogates Colitis and Ileitis in Mice

BACKGROUND

Although inflammatory bowel disease (IBD) is a failure in maintaining tolerance to the intestinal microbiota, few studies have investigated the use of immunologic tolerance as a treatment approach for IBD. We hypothesized that induction of immune tolerance at a distal site could suppress intestinal inflammation through a process of bystander regulation.

METHODS

Epicutaneous tolerance was induced by topical application of ovalbumin (OVA) using a Viaskin patch for 48 hours. In some experiments, a single feed of ovalbumin was used to drive epicutaneous tolerance-induced regulatory T cells (Tregs) to the intestine. The mechanism of tolerance induction was tested using neutralizing antibodies against TGF-β, IL-10, and Treg depletion using Foxp3-DTR mice. The capacity of skin-draining Tregs, or epicutaneous tolerance, to prevent or treat experimental IBD was tested using T-cell transfer colitis, dextran sodium sulfate (DSS) colitis, and ileitis in SAMP-YITFc mice. Weight loss, colonic inflammatory cytokines and histology were assessed.

RESULTS

Epicutaneous exposure to ovalbumin induced systemic immune tolerance by a TGF-β-dependent, but IL-10 and iFoxp3 Treg-independent mechanism. Skin draining Tregs suppressed the development of colitis. Epicutaneous tolerance to a model antigen prevented intestinal inflammation in the dextran sodium sulfate and SAMP-YITFc models and importantly could halt disease in mice already experiencing weight loss in the T-cell transfer model of colitis. This was accompanied by a significant accumulation of LAP and Foxp3 Tregs in the colon.

CONCLUSIONS

This is the first demonstration that epicutaneous tolerance to a model antigen can lead to bystander suppression of inflammation and prevention of disease progression in preclinical models of IBD.

Low-Dose Allergen-Specific Immunotherapy Induces Tolerance in a Murine Model of Shrimp Allergy

BACKGROUND

The efficacy and safety of allergen-specific immunotherapy (AIT) are highly dose-dependent.

METHODS

We investigated the dosage effects of AIT and the underlying mechanisms in a murine model of shrimp hypersensitivity. BALB/c mice were sensitized with recombinant shrimp allergen rMet e 1 and challenged orally with a high dose of rMet e 1 to elicit an allergic response. These sensitized mice were then treated with a low (0.01 mg), medium (0.05 mg), or high dosage (0.1 mg) of rMet e 1 intraperitoneally before receiving a second oral challenge. The allergic responses and immunological changes in the gut were compared between animals receiving different dosages.

RESULTS

We found that all sensitized mice that received rMet e 1 immunotherapy were desensitized, regardless of the dosage, and protected at the second oral challenge. Nevertheless, the mice in the high-dosage group experienced severe systemic reactions during the treatment phase. In contrast, regulatory T (Treg) cell-associated genes were upregulated only in the low- and medium-dosage groups, and Foxp3+ cells were more abundant in the gut lymphoid tissues than in the high-dosage group.

CONCLUSIONS

Our results demonstrate that low-dosage immunotherapy favors the induction of local Foxp3+ Treg cells and the upregulation of regulatory cytokines. The safety advantages and long-term efficacy of low-dosage immunotherapy should be taken into consideration when developing immunotherapy dose schedules.

Dietary Intervention with β-Lactoglobulin-Derived Peptides and a Specific Mixture of Fructo-Oligosaccharides and Bifidobacterium breve M-16V Facilitates the Prevention of Whey-Induced Allergy in Mice by Supporting a Tolerance-Prone Immune Environment

Cow's milk allergy (CMA) prevails in infants and brings increased risk of developing other allergic diseases. Oral administration of specific β-lactoglobulin (BLG)-derived peptides (PepMix) and a specific blend of short- and long-chain fructo-oligosaccharides and Bifidobacterium breve M-16V (FF/Bb) was found to partially prevent CMA development in mice. In this study, we aimed to expand the knowledge on the preventive potential and the underlying mechanisms of this approach. Three-week-old female C3H/HeOuJ mice were orally exposed to PepMix±FF/Bb prior to a 5-week oral sensitization with whole whey and cholera toxin as an adjuvant. The acute allergic skin response was determined after an intradermal challenge with whole whey protein. Following an oral challenge with whey, regulatory T cells (T_regs) in the small intestine lamina propria (SI-LP) and mRNA expression of immune markers in the Peyer's patches (PP) were investigated. The early impact of PepMix and FF/Bb interventions on the immune system during the oral tolerance (OT) induction phase was investigated after the last OT administration. Pre-exposing mice to PepMix+FF/Bb partially prevented the acute allergic skin response compared to PBS and increased T_regs and activated T cells in the SI-LP compared to sham-sensitized mice. It also increased the mRNA expression of Tbet over GATA3 in the PP of whey-sensitized mice. Directly upon the 6-day OT phase, FF/Bb intervention enhanced cecal content levels of propionic and butyric acid in PepMix-fed mice and the former was positively correlated with Foxp3⁺ cell numbers in the colon. In the PP of PepMix+FF/Bb-exposed mice, IL-22 mRNA expression increased and IL-10 followed the same tendency, while the Foxp3 expression was increased over GATA3 and RorγT. In the colon, the Tbet mRNA expression increased over GATA3, while IL-22 decreased. In addition, the Foxp3⁺/GATA3⁺ and regulatory/effector T cell ratios in the mesenteric lymph nodes and the CD11b⁺/CD11b^- conventional dendritic cells ratio in the SI-LP were increased. In conclusion, the FF/Bb diet facilitates the capacity of the specific BLG-peptides to partially prevent the allergic response after sensitization to whole whey protein, possibly by creating a tolerance-prone environment during the OT phase. Such a dietary intervention might contribute to tailoring successful strategies for CMA prevention.

Stem Cell Pathology

Rapid advances in stem cell biology and regenerative medicine have opened new opportunities for better understanding disease pathogenesis and the development of new diagnostic, prognostic, and treatment approaches. Many stem cell niches are well defined anatomically, thereby allowing their routine pathological evaluation during disease initiation and progression. Evaluation of the consequences of genetic manipulations in stem cells and investigation of the roles of stem cells in regenerative medicine and pathogenesis of various diseases such as cancer require significant expertise in pathology for accurate interpretation of novel findings. Therefore, there is an urgent need for developing stem cell pathology as a discipline to facilitate stem cell research and regenerative medicine. This review provides examples of anatomically defined niches suitable for evaluation by diagnostic pathologists, describes neoplastic lesions associated with them, and discusses further directions of stem cell pathology.

New species of Eimeria (Apicomplexa: Eimeriidae) from Thrichomys fosteri and Clyomys laticeps (Rodentia: Echimyidae) of the Brazilian Pantanal

The echimyid rodents Thrichomys fosteri and Clyomys laticeps are among the most commonly recorded small mammals in the Pantanal wetland of Brazil. These species play important ecological roles since they are the basis of the food chain of some predators and are parasitized by some pathogens. Knowledge of the eimerians that parasitize echimyid rodents in Brazil is absent, and only one report is available for South America. We therefore investigated parasitism by coccidians in the echimyids T. fosteri and C. laticeps in the Pantanal. Using morphological and morphometric features and associated statistical analyses, we describe five new eimerian species parasitizing T. fosteri (Eimeria nhecolandensis n. sp., Eimeria jansenae n. sp., and Eimeria fosteri n. sp.) and C. laticeps (E. nhecolandensis n. sp., Eimeria corumbaensis n. sp., and Eimeria laticeps n. sp.) in different types of infection associations. We document the developmental forms in the tissues, and describe lesions in the enteric tract of some infected animals. We also discuss some approaches regarding epidemiological and ecological data. Our results demonstrate that echimyid rodents in the Brazilian Pantanal are important hosts for the maintenance of enteric coccidia. Moreover, in some circumstances, this parasitism may threaten the health of the hosts.

Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism

Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells.

Bovine antibodies targeting primary and recurrent Clostridium difficile disease are a potent antibiotic alternative

The increased incidence of antibiotic resistant 'superbugs' has amplified the use of broad spectrum antibiotics worldwide. An unintended consequence of antimicrobial treatment is disruption of the gastrointestinal microbiota, resulting in susceptibility to opportunistic pathogens, such as Clostridium difficile. Paradoxically, treatment of C. difficile infections (CDI) also involves antibiotic use, leaving patients susceptible to re-infection. This serious health threat has led to an urgent call for the development of new therapeutics to reduce or replace the use of antibiotics to treat bacterial infections. To address this need, we have developed colostrum-derived antibodies for the prevention and treatment of CDI. Pregnant cows were immunised to generate hyperimmune bovine colostrum (HBC) containing antibodies that target essential C. difficile virulence components, specifically, spores, vegetative cells and toxin B (TcdB). Mouse infection and relapse models were used to compare the capacity of HBC to prevent or treat primary CDI as well as prevent recurrence. Administration of TcdB-specific colostrum alone, or in combination with spore or vegetative cell-targeted colostrum, prevents and treats C. difficile disease in mice and reduces disease recurrence by 67%. C. difficile-specific colostrum should be re-considered as an immunotherapeutic for the prevention or treatment of primary or recurrent CDI.

Chemically induced mouse models of acute and chronic intestinal inflammation

Inflammatory bowel diseases (IBDs) result in diarrhea and abdominal pain with further potential complications such as tissue fibrosis and stenosis. Animal models help in understanding the immunopathogenesis of IBDs and in the design of novel therapeutic concepts. Here we present an updated version of a protocol we published in 2007 for key models of acute and chronic forms of colitis induced by 2,4,6-trinitro-benzene sulfonic acid (TNBS), oxazolone and dextran sulfate sodium (DSS). This protocol update describes an adaptation of the existing protocol that modifies the technique. This protocol has been used to generate improved mouse models that better reflect the nature of IBDs in humans. In TNBS and oxazolone colitis models, topical administration of hapten reagents results in T-cell-mediated immunity against haptenized proteins and luminal antigens. By contrast, to generate DSS colitis models, mice orally receive DSS, causing death of epithelial cells, compromising barrier function and causing subsequent inflammation. The analysis of the acute colitis models can be performed within 1-2 weeks, whereas that of the chronic models may take 2-4 months. The strengths of the acute models are that they are based on the analysis of short-lasting barrier alterations, innate immune effects and flares. The advantages of the chronic models are that they may offer better insight into adaptive immunity and complications such as neoplasia and tissue fibrosis. The protocol requires basic skills in laboratory animal research.

Inflammatory cytokines down-regulate the barrier-protective prostasin-matriptase proteolytic cascade early in experimental colitis

Compromised gastrointestinal barrier function is strongly associated with the progressive and destructive pathologies of the two main forms of irritable bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD). Matriptase is a membrane-anchored serine protease encoded by suppression of tumorigenicity-14 (ST14) gene, which is critical for epithelial barrier development and homeostasis. Matriptase barrier-protective activity is linked with the glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin, which is a co-factor for matriptase zymogen activation. Here we show that mRNA and protein expression of both matriptase and prostasin are rapidly down-regulated in the initiating inflammatory phases of dextran sulfate sodium (DSS)-induced experimental colitis in mice, and, significantly, the loss of these proteases precedes the appearance of clinical symptoms, suggesting their loss may contribute to disease susceptibility. We used heterozygous St14 hypomorphic mice expressing a promoter-linked β-gal reporter to show that inflammatory colitis suppresses the activity of the St14 gene promoter. Studies in colonic T84 cell monolayers revealed that barrier disruption by the colitis-associated Th2-type cytokines, IL-4 and IL-13, down-regulates matriptase as well as prostasin through phosphorylation of the transcriptional regulator STAT6 and that inhibition of STAT6 with suberoylanilide hydroxamic acid (SAHA) restores protease expression and reverses cytokine-induced barrier dysfunction. Both matriptase and prostasin are significantly down-regulated in colonic tissues from human subjects with active ulcerative colitis or Crohn's disease, implicating the loss of this barrier-protective protease pathway in the pathogenesis of irritable bowel disease.

Intestinal Epithelial Cell-Specific Deletion of PLD2 Alleviates DSS-Induced Colitis by Regulating Occludin

Ulcerative colitis is a multi-factorial disease involving a dysregulated immune response. Disruptions to the intestinal epithelial barrier and translocation of bacteria, resulting in inflammation, are common in colitis. The mechanisms underlying epithelial barrier dysfunction or regulation of tight junction proteins during disease progression of colitis have not been clearly elucidated. Increase in phospholipase D (PLD) activity is associated with disease severity in colitis animal models. However, the role of PLD2 in the maintenance of intestinal barrier integrity remains elusive. We have generated intestinal-specific Pld2 knockout mice (Pld2 IEC-KO) to investigate the mechanism of intestinal epithelial PLD2 in colitis. We show that the knockout of Pld2 confers protection against dextran sodium sulphate (DSS)-induced colitis in mice. Treatment with DSS induced the expression of PLD2 and downregulated occludin in colon epithelial cells. PLD2 was shown to mediate phosphorylation of occludin and induce its proteasomal degradation in a c-Src kinase-dependent pathway. Additionally, we have shown that treatment with an inhibitor of PLD2 can rescue mice from DSS-induced colitis. To our knowledge, this is the first report showing that PLD2 is pivotal in the regulation of the integrity of epithelial tight junctions and occludin turn over, thereby implicating it in the pathogenesis of colitis.