| 1. |
- Da Silva, Stéphanie
(author)
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Stress disrupts intestinal mucus barrier in rats via mucin O-glycosylation shift : prevention by a probiotic treatment
- 2014
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - Rockville, MD, United States : American Physiological Society. - 0193-1857 .- 1522-1547. ; 307:4, s. G420-G429
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Journal article (peer-reviewed)abstract
- Despite well-known intestinal epithelial barrier impairment and visceral hypersensitivity in irritable bowel syndrome (IBS) patients and IBS-like models, structural and physical changes in the mucus layer remain poorly understood. Using a water avoidance stress (WAS) model, we aimed at evaluating whether 1) WAS modified gut permeability, visceral sensitivity, mucin expression, biochemical structure of O-glycans, and related mucus physical properties, and 2) whether Lactobacillus farciminis treatment prevented these alterations. Wistar rats received orally L. farciminis or vehicle for 14 days; at day 10, they were submitted to either sham or 4-day WAS. Intestinal paracellular permeability and visceral sensitivity were measured in vivo. The number of goblet cells and Muc2 expression were evaluated by histology and immunohistochemistry, respectively. Mucosal adhesion of L. farciminis was determined ex situ. The mucin O-glycosylation profile was obtained by mass spectrometry. Surface imaging of intestinal mucus was performed at nanoscale by atomic force microscopy. WAS induced gut hyperpermeability and visceral hypersensitivity but did not modify either the number of intestinal goblet cells or Muc2 expression. In contrast, O-glycosylation of mucins was strongly affected, with the appearance of elongated polylactosaminic chain containing O-glycan structures, associated with flattening and loss of the mucus layer cohesive properties. L. farciminis bound to intestinal Muc2 and prevented WAS-induced functional alterations and changes in mucin O-glycosylation and mucus physical properties. WAS-induced functional changes were associated with mucus alterations resulting from a shift in O-glycosylation rather than from changes in mucin expression. L. farciminis treatment prevented these alterations, conferring epithelial and mucus barrier strengthening.
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| 2. |
- Ermund, Anna, et al.
(author)
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Studies of mucus in mouse stomach, small intestine, and colon. I. Gastrointestinal mucus layers have different properties depending on location as well as over the Peyer's patches.
- 2013
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In: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 305:5
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Journal article (peer-reviewed)abstract
- Colon has been shown to have a two-layered mucus system where the inner layer is devoid of bacteria. However, a complete overview of the mouse gastrointestinal mucus system is lacking. We now characterize mucus release, thickness, growth over time, adhesive properties, and penetrability to fluorescent beads from stomach to distal colon. Colon displayed spontaneous mucus release and all regions released mucus in response to carbachol and PGE2, except the distal colon and domes of Peyer's patches. Stomach and colon had an inner mucus layer that was adherent to the epithelium. In contrast, the small intestine and Peyer's patches had a single mucus layer that was easily aspirated. The inner mucus layer of the distal colon was not penetrable to beads the size of bacteria and the inner layer of the proximal colon was only partly penetrable. In contrast, the inner mucus layer of stomach was fully penetrable, as was the small intestinal mucus. This suggests a functional organization of the intestinal mucus system, where the small intestine has loose and penetrable mucus that may allow easy penetration of nutrients, in contrast to the stomach, where the mucus provides physical protection, and the colon, where the mucus separates bacteria from the epithelium. This knowledge of the mucus system and its organization improves our understanding of the gastrointestinal tract physiology.
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| 3. |
- Gustafsson, JK, et al.
(author)
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Amygdala activation by corticosterone alters visceral and somatic pain in cycling female rats
- 2011
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In: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 300:6, s. G1080-G1085
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Journal article (peer-reviewed)abstract
- Irritable bowel syndrome (IBS) is often seen in women, and symptom severity is known to vary over the menstrual cycle. In addition, activation of the hypothalamic-pituitary-adrenal (HPA) axis enhances symptomology and patients with IBS have increased activation of the amygdala, a brain region known to facilitate HPA output. However, little is known about the effects of amygdala activation during different stages of the menstrual cycle. We therefore investigated the effects of amygdala activation on somatic and visceral pain perception over the rat estrous cycle. Female Wistar rats were implanted with either corticosterone (Cort) or cholesterol as a control onto the dorsal margin of the central amygdala. Visceral sensitivity was quantified by recording the visceromotor response (VMR) to colorectal distension (CRD) and somatic sensitivity was assessed via the Von Frey test. In cholesterol controls, both visceral and somatic sensitivity varied over the estrous cycle. Rats in proestrus/estrus responded to CRD with an increased VMR compared with rats in metestrus/diestrus. Somatic sensitivity followed a similar pattern with enhanced sensitivity during proestrus/estrus compared with metestrus/diestrus. Elevated amygdala Cort induced visceral hypersensitivity during metestrus/diestrus but had no effect during proestrus/estrus. In contrast, elevated amygdala Cort increased somatic sensitivity during both metestrus/diestrus and proestrus/estrous. These results suggests that amygdala activation by Cort eliminates spontaneously occurring differences in visceral and somatic pain perception, which could explain the lowered pain thresholds and higher incidence of somatic pain observed in women with IBS.
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| 4. |
- Gustafsson, Jenny K, 1981, et al.
(author)
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An ex vivo method for studying mucus formation, properties and thickness in human colonic biopsies and mouse small and large intestinal explants.
- 2012
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In: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 302:4, s. 430-438
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Journal article (peer-reviewed)abstract
- The colon mucus layers minimize the contact between the luminal flora and the epithelial cells and defects in this barrier may lead to colonic inflammation. We now describe an ex vivo method for analysis of mucus properties in human colon and mouse small and large intestine. Materials and methods: Intestinal explants were mounted in horizontal perfusion chambers. The mucus surface was visualized by adding charcoal particles on the apical side and mucus thickness was measured using a micropipette. Mucus thickness, adhesion and growth rate was recorded for 1 h. In mouse and human colon, the ability of the mucus to act as a barrier to beads the size of bacteria was also evaluated. Tissue viability was monitored by transepithelial potential difference. Results: In mouse ileum the mucus could be removed by gentle aspiration, whereas in colon about 40 µm of the mucus remained attached to the epithelial surface. Both mouse and human colon had an inner mucus layer that was not penetrated by the fluorescent beads. Spontaneous mucus growth was observed in human (240 µm/h) and mouse (100 µm/h) colon, but not in mouse ileum. In contrast, stimulation with carbachol induced a higher mucus secretion in ileum than colon (mouse ileum: Δ200 μm, mouse colon: Δ130 µm, human colon: Δ140 μm). In conclusion, while retaining key properties from the mucus system in vivo, this set up also allows for studies of the highly dynamic mucus system under well controlled conditions.
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| 5. |
- Holmén Larsson, Jessica, 1971, et al.
(author)
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Studies of mucus in mouse stomach, small intestine, and colon. III. Gastrointestinal Muc5ac and Muc2 mucin O-glycan patterns reveal a regiospecific distribution
- 2013
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In: American Journal of Physiology-Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 305:5
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Journal article (peer-reviewed)abstract
- The mouse intestinal mucus is mainly made up by the gel-forming Muc2 mucin and the stomach surface mucus Muc5ac, both extensively O-glycosylated. The oligosaccharide diversity provides a vast library of potential recognition sites for both commensal and pathogenic organisms. The mucin glycans are thus likely very important for the selection and maintenance of a stable intestinal flora. Here we have explored the O-glycan patterns of the mouse gastrointestinal tract mucins. The mucins from the mucus of the distal and proximal colon, ileum, jejunum, duodenum, and stomach of conventionally raised wild-type (C57BL/6) mice were separated by composite gel electrophoresis. The O-linked glycans were released by reductive elimination and structurally characterized by liquid chromatography-mass spectrometry. The mucins glycans were mostly core 2 type [Gal beta 1-3(GlcNAc beta 1-6)GalNAcol], but also core 1 (Gal beta 1-3GalNAcol). In the stomach about half of the Muc5ac mucin O-glycans were neutral and many monosulfated, but with a low grade of sialylation and fucosylation. Mouse ileum, jejunum, and duodenum had similar glycan patterns dominated by sialylated and sulfated core 2 glycans, but few fucosylated. Colon was on the other hand dominated by highly charged fucosylated glycans. The distal colon is different from the proximal colon because different biosynthetic pathways are utilized, although sialylated and sulfated glycans were highly abundant in both parts. The sulfation was higher in the distal colon, whereas sialic acid was more common in the proximal colon. Many fucosylated glycans were found in both the proximal and distal colon. Thus the mucin O-glycans vary along the mouse gastrointestinal tract.
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| 6. |
- Karczewski, Jurgen, et al.
(author)
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Regulation of human epithelial tight junction proteins by Lactobacillus plantarum in vivo and protective effects on the epithelial barrier
- 2010
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 298:6, s. G851-G859
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Journal article (peer-reviewed)abstract
- Lactobacillus plantarum, a commensal bacterium of humans, has been proposed to enhance the intestinal barrier, which is compromised in a number of intestinal disorders. To study the effect of L. plantarum strain WCFS1 on human barrier function, healthy subjects were administered L. plantarum or placebo in the duodenum for 6 h by means of a feeding catheter. The scaffold protein zonula occludens (ZO)-1 and transmembrane protein occludin were found to be significantly increased in the vicinity of the tight-junction (TJ) structures, which form the paracellular seal between cells of the epithelium. In an in vitro model of the human epithelium, L. plantarum induced translocation of ZO-1 to the TJ region; however, the effects on occludin were minor compared with those seen in vivo. L. plantarum was shown to activate Toll-like receptor 2 (TLR2) signaling, and treatment of Caco-2 monolayers with the TLR2 agonist Pam3-Cys-SK4(PCSK) significantly increased fluorescent staining of occludin in the TJ. Pretreatment of Caco-2 monolayers with L. plantarum or PCSK significantly attenuated the effects of phorbol ester-induced dislocation of ZO-1 and occludin and the associated increase in epithelial permeability. Our results identifying commensal bacterial stimulation of TLR2 in the gut epithelium as a regulator of epithelial integrity have important implications for understanding probiotic mechanisms and the control of intestinal homeostasis.
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| 7. |
- Kober, Olivia, et al.
(author)
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γδ T-cell-deficient mice show alterations in mucin expression, glycosylation and goblet cells but maintain an intact mucus layer.
- 2014
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 306:7, s. G582-G593
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Journal article (peer-reviewed)abstract
- Intestinal homeostasis is maintained by a hierarchy of immune defences acting in concert to minimize contact between luminal microorganisms and the intestinal epithelial cell surface. The intestinal mucus layer, covering the gastrointestinal (GI) tract epithelial cells, contributes to mucosal homeostasis by limiting bacterial invasion. In this study, we used γδ T-cell-deficient (TCRδ(-/-)) mice to examine whether and how γδ T-cells modulate the properties of the intestinal mucus layer. Increased susceptibility of TCRδ(-/-) mice to dextran sodium sulphate (DSS)-induced colitis is associated with a reduced number of goblet cells. Alterations in the number of goblet cells and crypt lengths were observed in the small intestine (SI) and colon of TCRδ(-/-) mice compared to C57BL/6 wt mice. Addition of keratinocyte growth factor (KGF) to small intestinal organoid cultures from TCRδ(-/-) mice showed a marked increase in crypt growth, and both goblet cell number and redistribution along the crypts. There was no apparent difference in the thickness or organisation of the mucus layer between TCRδ(-/-) and wt mice, as measured in vivo. However, γδ T-cell deficiency led to reduced sialylated mucins in association with increased gene expression of gel-secreting Muc2 and membrane-bound mucins, including Muc13 and Muc17. Collectively, these data provide evidence that γδ T cells play an important role in maintenance of mucosal homeostasis by regulating mucin expression and promoting goblet cell function in the small intestine.
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| 8. |
- Korecka, A, et al.
(author)
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ANGPTL4 expression induced by butyrate and rosiglitazone in human intestinal epithelial cells utilizes independent pathways
- 2013
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In: American journal of physiology. Gastrointestinal and liver physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 304:11, s. G1025-G1037
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Journal article (peer-reviewed)abstract
- Short-chain fatty acids (SCFAs), such as butyrate and propionate, are metabolic products of carbohydrate fermentation by the microbiota and constitute the main source of energy for host colonocytes. SCFAs are also important for gastrointestinal health, immunity, and host metabolism. Intestinally produced angiopoietin-like protein 4 (ANGPTL4) is a secreted protein with metabolism-altering properties and may offer a route by which microbiota can regulate host metabolism. Peroxisome proliferator-activated receptor (PPAR)-γ has previously been shown to be involved in microbiota-induced expression of intestinal ANGPTL4, but the role of bacterial metabolites in this process has remained elusive. Here, we show that the SCFA butyrate regulates intestinal ANGPTL4 expression in a PPAR-γ-independent manner. Although PPAR-γ is not required for butyrate-driven intestinal ANGPTL4 expression, costimulating with PPAR-γ ligands and SCFAs leads to additive increases in ANGPTL4 levels. We suggest that PPAR-γ and butyrate rely on two separate regulatory sites, a PPAR-responsive element downstream the transcription start site and a butyrate-responsive element(s) within the promoter region, 0.5 kb upstream of the transcription start site. Furthermore, butyrate gavage and colonization with Clostridium tyrobutyricum, a SCFA producer, can independently induce expression of intestinal ANGPTL4 in germ-free mice. Thus, oral administration of SCFA or use of SCFA-producing bacteria may be additional routes to maintain intestinal ANGPTL4 levels for preventive nutrition or therapeutic purposes.
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| 9. |
- Liu, Haoyu, et al.
(author)
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Expression of heat shock proteins 27 and 72 correlates with specific commensal microbes in different regions of porcine gastrointestinal tract
- 2014
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In: AJP - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 306, s. G1033-G1041
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Journal article (peer-reviewed)abstract
- The gastrointestinal (GI) tract of mammals is inhabited by trillions of microorganisms, resulting in exceedingly complex networking. The interaction between distinct bacterial species and the host immune system is essential in maintaining homeostasis in the gut ecosystem. For instance, the gut commensal microbiota dictates intestinal mucosa maturation and its abundant immune components, such as cytoprotective heat shock proteins (HSP). Here we examined physiological expression of HSP in the normal porcine GI tract and found it to be gut region-and cell type-specific in response to dietary components, microbes, and microbial metabolites to which the mucosa surface is exposed. Correlations between HSP72 expression and ileal Lactobacillus spp. and colonic clostridia species, and between HSP27 expression and uronic acid ingestion, were important interplays identified here. Thus this study provides novel insights into host-microbe interactions shaping the immune system that are modifiable by dietary regime.
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| 10. |
- Merza, Mohammed, et al.
(author)
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Human thrombin-derived host defense peptides inhibit neutrophil recruitment and tissue injury in severe acute pancreatitis.
- 2014
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In: American Journal of Physiology: Gastrointestinal and Liver Physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 307:9, s. 914-921
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Journal article (peer-reviewed)abstract
- Severe acute pancreatitis (AP) is characterized by leukocyte infiltration and tissue injury. Herein, we wanted to examine the potential effects of thrombin-derived host defense peptides (TDPs) in severe AP. Pancreatitis was provoked by infusion of taurocholate into the pancreatic duct or by intraperitoneal administration of L-arginine in C57BL/6 mice. Animals were treated with the TDPs GKY20 and GKY25 or a control peptide WFF25 30 min before induction of AP. TDPs reduced blood amylase levels, neutrophil infiltration, hemorrhage, necrosis and edema formation in the inflamed pancreas. Treatment with TDPs markedly attenuated the taurocholate-induced increase in plasma levels of CXCL2 and interleukin-6. Moreover, administration of TDPs decreased histone 3, histone 4 and MPO levels in the pancreas in response to taurocholate challenge. Interestingly, administration of TDPs abolished neutrophil expression of Mac-1 in mice with pancreatitis. In addition, TDPs inhibited CXCL2-induced chemotaxis of isolated neutrophils in vitro. Fluorescent-labeled TDP was found to directly bind to isolated neutrophils. Finally, a beneficial effect of TDPs was confirmed in L-arginine-induced pancreatitis. Our novel results demonstrate that TDPs exert protective effects against pathological inflammation and tissue damage in AP. These novel findings suggest that TDPs might be useful in the management of patients with severe AP.
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