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Intestinal ischemia-reperfusion injury (IRI) is a common clinical entity, and its outcome is unpredictable due to the triad of inflammation, increased permeability and bacterial translocation. Polyethylene glycol (PEG) is a polyether compound that is extensively used in pharmacology as an excipient in various products. More recently, this class of products have shown to have potent anti-inflammatory, anti-apoptotic, immunosuppressive and cell-membrane-stabilizing properties. However, its effects on the outcome after intestinal IRI have not yet been investigated. We hypothesized that PEG administration would reduce the effects of intestinal IRI in rodents. In a previously described rat model of severe IRI (45 min of ischemia followed by 60 min of reperfusion), we evaluated the effect of IV PEG administration at different doses (50 and 100 mg/kg) before and after the onset of ischemia. In comparison to control animals, PEG administration stabilized the endothelial glycocalyx, leading to reduced reperfusion edema, bacterial translocation and inflammatory reaction as well as improved 7-day survival. These effects were seen both in a pretreatment and in a treatment setting. The fact that this product is readily available and safe should encourage further clinical investigations in settings of intestinal IRI, organ preservation and transplantation. more...

Intestinal ischemia-reperfusion injury (IRI) is a common clinical entity, and its outcome is unpredictable due to the triad of inflammation, increased permeability and bacterial translocation. Polyethylene glycol (PEG) is a polyether compound that is extensively used in pharmacology as an excipient in various products. More recently, this class of products have shown to have potent anti-inflammatory, anti-apoptotic, immunosuppressive and cell-membrane-stabilizing properties. However, its effects on the outcome after intestinal IRI have not yet been investigated. We hypothesized that PEG administration would reduce the effects of intestinal IRI in rodents. In a previously described rat model of severe IRI (45 min of ischemia followed by 60 min of reperfusion), we evaluated the effect of IV PEG administration at different doses (50 and 100 mg/kg) before and after the onset of ischemia. In comparison to control animals, PEG administration stabilized the endothelial glycocalyx, leading to reduced reperfusion edema, bacterial translocation and inflammatory reaction as well as improved 7-day survival. These effects were seen both in a pretreatment and in a treatment setting. The fact that this product is readily available and safe should encourage further clinical investigations in settings of intestinal IRI, organ preservation and transplantation. more...

Animal research in intestinal ischemia-reperfusion injury (IRI) is mainly performed in rodent models. Previously, intraperitoneal (I.P.) injections with ketamine-xylazine mixtures were used. Nowadays, volatile anesthetics (isoflurane) are more common. However, the impact of the anesthetic method on intestinal IRI has not been investigated. We aim to analyze the different anesthetic methods and their influence on the extent of intestinal IRI in a rat model. Male Sprague-Dawley rats were used to investigate the effect of I.P. anesthesia on 60 min of intestinal ischemia and 60 min of reperfusion in comparison to hyperoxygenation (100% O2) and volatile isoflurane anesthesia. In comparison to I.P. anesthesia with room air (21% O2), supplying 100% O2 improved 7-day survival by cardiovascular stabilization, reducing lactic acidosis and preventing vascular leakage. However, this had no effect on the intestinal epithelial damage, permeability, and inflammatory response observed after intestinal IRI. In contrast to I.P. + 100% O2, isoflurane anesthesia reduced intestinal IRI by preventing ongoing low-flow reperfusion hypotension, limiting intestinal epithelial damage and permeability, and by having anti-inflammatory effects. When translating the aforementioned results of this study to clinical situations, such as intestinal ischemia or transplantation, the potential protective effects of hyperoxygenation and volatile anesthetics require further research. ispartof: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES vol:24 issue:3 ispartof: location:Switzerland status: published more...

Background: Human exposure to high doses of radiation resulting in acute radiation syndrome and death could rapidly escalate to a mass casualty catastrophe in the event of nuclear accidents or terrorism. The primary reason is that there is presently no effective treatment option, especially for radiation-induced gastrointestinal syndrome. This syndrome results from disruption of mucosal barrier integrity leading to severe dehydration, blood loss and sepsis. In this study, we tested whether small extracellular vesicles/exosomes derived from mesenchymal stromal cells (MSC) could reduce radiation-related mucosal barrier damage and reduce radiation-induced animal mortality. Methods: Human MSC-derived small extracellular vesicles/exosomes were intravenously administered to NUDE mice, 3, 24 and 48 hours after lethal whole-body irradiation (10 Gy). Integrity of the small intestine epithelial barrier was assessed by morphologic analysis, immunostaining for tight junction protein (claudin-3) and in vivo permeability to 4 kDa FITC-labeled dextran. Renewal of small intestinal epithelium was determined by the quantification of epithelial cell apoptosis (TUNEL staining) and proliferation (Ki67 immunostaining). Statistical analyses were performed using one-way ANOVA followed by a Tukey test. Statistical analyses of mouse survival were performed using the methods of Kaplan-Meier and Cox. Results: We demonstrated that MSC-derived small extracellular vesicles/exosomes treatment reduced by 85% the instantaneous mortality risk in mice subjected to 10 Gy whole-body irradiation and thus increased their survival time. This effect could be attributed to the efficacy of MSC-derived small extracellular vesicles/exosomes in reducing mucosal barrier disruption. We showed that MSC-derived small extracellular vesicles/exosomes improved renewal of the small intestinal epithelium by stimulating proliferation and inhibiting apoptosis of the epithelial crypt cells. MSC-derived small extracellular vesicles/exosomes also reduced radiation-induced mucosal permeability as evidenced by the preservation of claudin-3 immunostaining at the tight junctions of the epithelium. Conclusions: MSC-derived small extracellular vesicles/exosomes promote epithelial repair and regeneration and preserve structural integrity of the intestinal epithelium in mice exposed to radiation-induced gastrointestinal toxicity. Our results suggest that the administration of MSC-derived small extracellular vesicles/exosomes could be a treatment modality to limit acute radiation syndrome. more...

Background Among the different mechanisms involved in irritable bowel syndrome (IBS) physiopathology, visceral hypersensitivity seems to play a key role. It involves sensitization of the colonic primary afferent fibers, especially through an overexpression of ion channels. The aims of this translational study were to investigate the colonic expression of Cav3.2 calcium channels and their involvement in an animal model of colonic hypersensitivity, and to assess their expression in the colonic mucosa of symptomatic IBS patients. Methods This bench-to-bed study combined a preclinical experimental study on mice and a case–control clinical study. Preclinical studies were performed on wild-type and Cav3.2-KO mice. Colonic sensitivity and Cav3.2 expression were studied after a low-dose treatment of dextran sodium sulfate (DSS 0.5%). Regarding the clinical study, colonic biopsies were performed in 14 IBS patients and 16 controls during a colonoscopy to analyze the mucosal Cav3.2 expression. Key results Wild-type, but not Cav3.2-KO, mice developed visceral hypersensitivity without colonic inflammation, after 0.5% DSS treatment. A significant increase of Cav3.2 mRNA (p = 0.04) was found in the colon of low-dose DSS-treated wild-type (WT) mice compared to their controls. In human colonic biopsies, the Cav3.2 mRNA level was significantly higher in the IBS group compared to the control group (p = 0.01). The immunofluorescence staining revealed their protein expression in colonic mucosa, particularly in nerve fibers. Conclusions & inferences This translational study supports the involvement of the calcium channels Cav3.2 in abdominal pain, as observed in IBS patients. It opens new therapeutic perspectives based on molecules specifically blocking these channels. more...

We read with interest the study by Higuchi et al , which identified mechanisms of increased satiation in Cyp8b1−/− mice via slowed gastric empting.1 Following data showing that deleting Cyp8b1, which is required to produce 12α-hydroxylated bile acids, impaired intestinal lipid absorption in mice, the authors convincingly demonstrated that lowering 12α-hydroxylated bile acids slowed gastric emptying in Cyp8b1−/− mice.1 Duodenal lipid infusion affects gastric function, and duodenal hypersensitivity to lipids has been studied in GI disorders with gastric dysmotility, such as functional dyspepsia (FD).2 FD is defined by upper GI symptoms originating from the gastroduodenal region with no structural disease on routine investigation.3 Although studies showed that lipids are a major trigger of dyspeptic symptoms, the effect was only partially explained by duodenal release of cholecystokinin.4 Interestingly, the release of bile salts has been linked to the generation of dyspeptic symptoms, possibly via duodenal luminal or mucosal changes including hyperpermeability.5 6 However, duodenal alterations have not … more...