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- Wallon, Conny, et al.
(författare)
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Corticotropin releasing hormone (CRH) regulates macromolecular permeability via mast cells in normal human colonic biopsies in vitro
- 2008
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Ingår i: Gut. - London UK : BMJ Group. - 0017-5749 .- 1468-3288. ; 57:1, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Persistent stress and life events affect the course of ulcerativecolitis and irritable bowel syndrome by largely unknown mechanisms.Corticotropin-releasing hormone (CRH) has been implicated asan important mediator of stress-induced abnormalities in intestinalmucosal function in animal models, but to date no studies inhuman colon have been reported. The aim was to examine the effectsof CRH on mucosal barrier function in the human colon and toelucidate the mechanisms involved in CRH-induced hyper-permeability.Design: Biopsies from 39 volunteers were assessed for macromolecularpermeability (horseradish peroxidise (HRP), 51Cr-EDTA), andelectrophysiology after CRH challenge in Ussing chambers. Thebiopsies were examined by electron and confocal microscopy forHRP and CRH receptor localisation, respectively. Moreover, CRHreceptor mRNA and protein expression were examined in the humanmast cell line, HMC-1.Results: Mucosal permeability to HRP was increased by CRH (2.8±0.5pmol/cm2/h) compared to vehicle exposure (1.5±0.4 pmol/cm2/h),p = 0.032, whereas permeability to 51Cr-EDTA and transmucosalelectrical resistance were unchanged. The increased permeabilityto HRP was abolished by -helical CRH (9-41) (1.3±0.6pmol/cm2/h) and the mast cell stabiliser, lodoxamide (1.6±0.6pmol/cm2/h). Electron microscopy showed transcellular passageof HRP through colonocytes. CRH receptor subtypes R1 and R2were detected in the HMC-1 cell line and in lamina propria mastcells in human colon.Conclusions: Our results suggest that CRH mediates transcellular uptake ofHRP in human colonic mucosa via CRH receptor subtypes R1 andR2 on subepithelial mast cells. CRH-induced macromolecular uptakein human colon mucosa may have implications for stress-relatedintestinal disorders.
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| 2. |
- Keita, Åsa V, et al.
(författare)
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Characterization of antigen and bacterial transport in the follicle-associated epithelium of human ileum
- 2006
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Ingår i: Laboratory investigation. - : Elsevier BV. - 0023-6837 .- 1530-0307. ; 86:5, s. 504-516
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Tidskriftsartikel (refereegranskat)abstract
- The follicle-associated epithelium (FAE), covering Peyer's patches, provides a route of entry for antigens and microorganisms. Animal studies showed enhanced antigen and bacterial uptake in FAE, but no study on barrier function of human FAE has been reported. Our aim was to characterize the normal barrier properties of human FAE. Specimens of normal ileum were taken from 30 patients with noninflammatory colonic disease. Villus epithelium (VE) and FAE were identified and mounted in Ussing chambers. Permeability to 51Cr-EDTA, transmucosal flux of the protein antigen, horseradish peroxidase (HRP), and transport of fluorescent Escherichia coli (chemically killed K-12 and live HB101) were measured. Uptake mechanisms were studied by confocal- and transmission electron microscopy, and by using pharmacological inhibitors in an in vitro coculture model of FAE and in human ileal FAE. HRP flux was substantially higher in FAE than in VE, and was reduced by an amiloride analog. Electron microscopy showed HRP-containing endosomes. Transport of E. coli K-12 and HB101 was also augmented in FAE and was confirmed by confocal microscopy. In vitro coculture experiments and electron microscopy revealed actin-dependent, mainly transcellular, uptake of E. coli K-12 into FAE. 51Cr-EDTA permeability was equal in FAE and VE. Augmented HRP flux and bacterial uptake but similar paracellular permeability, suggest functional variations of transcellular transport in the FAE. We show for the first time that FAE of human ileum is functionally distinct from regular VE, rendering the FAE more prone to bacterial–epithelial cell interactions and delivery of antigens to the mucosal immune system.
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| 3. |
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| 4. |
- Münch, Andreas, 1970-, et al.
(författare)
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Dynamics of mucosal permeability and inflammation in collagenous colitis before, during, and after loop ileostomy
- 2005
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Ingår i: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 54:8, s. 1126-1128
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Tidskriftsartikel (refereegranskat)abstract
- Collagenous colitis has become a more frequent diagnosis but the aetiology of this disease is still unknown. We describe a female patient with intractable collagenous colitis who was treated with a temporary loop ileostomy. She was followed clinically, histopathologically, and functionally by measuring mucosal permeability before surgery, after ileostomy, and after bowel reconstruction. In our case report, active collagenous colitis was combined with increased transcellular and paracellular mucosal permeability. Diversion of the faecal stream decreased inflammation of the mucosa and normalised epithelial degeneration and mucosal permeability. After restoration of bowel continuity, mucosal permeability was altered prior to the appearance of a collagenous layer.
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| 5. |
- Wallon, Conny, et al.
(författare)
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Corticotropin-Releasing Hormone and Mast Cells in the Regulation of Mucosal Barrier Function in the Human Colon
- 2009
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Ingår i: MOLECULAR STRUCTURE AND FUNCTION OF THE TIGHT JUNCTION: FROM BASIC MECHANISMS TO CLINICAL MANIFESTATIONS. - : Wiley. - 0077-8923. ; 1165, s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- Corticotropin-releasing hormone (CRH) is an important neuro-endocrine mediator of the stress response. Local effects of CRH in the intestinal mucosa have become evident in recent years. We showed that CRH activates CRH receptor subtypes R1 and R2 on subepithelial mast cells, thereby inducing increased transcellular uptake of protein antigens in human colonic biopsies in Ussing chambers. Ongoing studies also implicate local cholinergic signaling in regulation of macromolecular permeability in the human colon. Since increased uptake of antigenic molecules is associated with mucosal inflammation, our findings may have implications for understanding stress-related intestinal disorders.
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| 6. |
- Wallon, Conny, et al.
(författare)
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Endoscopic biopsies in Ussing chambers evaluated for studies of macromolecular permeability in the human colon
- 2005
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 40:5, s. 586-595
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Tidskriftsartikel (refereegranskat)abstract
- Objective Studies of mucosal permeability to protein antigens in humans are limited to in vitro techniques. The use of surgical specimens for such studies has major shortcomings. Endoscopic biopsies in Ussing chambers have been introduced as a means of studying secretion and transepithelial permeability, but have not been evaluated for studies of protein antigen uptake in human intestine. Material and methods Standard forceps biopsies from the sigmoid colon of 24 healthy volunteers were mounted in Ussing chambers with an exposed tissue area of 1.76 mm2. 51Cr-EDTA (paracellular probe) and horseradish peroxidase (HRP; 45 kDa protein antigen) were used as permeability markers. Mucosal permeability, electrophysiology, histology and energy contents of the biopsies were studied over time. To evaluate the ability of the technique to detect permeability changes, the mucosa was modulated with capric acid, a medium-chain fatty acid, known to affect tight junctions. Results In the Ussing chamber the mucosal biopsies were viable for 160 min with stable levels of ATP and lactate, and only minor changes in morphology. Steady-state permeability with low variability was seen for both markers during the 30-90 min period. Exposure to capric acid induced a rapid decrease in short-circuit current (Isc) and a slower reversible decrease in transepithelial resistance (TER), as well as an increased permeability to 51Cr-EDTA and HRP. Conclusions Endoscopic biopsies of human colon are viable in Ussing chambers and are reliable tools for studies of mucosal permeability to protein antigens. The technique offers a broad potential for studies of mucosal function in the pathophysiology of human gastrointestinal diseases.
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