@article{moeser_haskell_shifflett_little_schultz_blikslager_2004, title={CIC-2 chloride secretion mediates prostaglandin-induced recovery of barrier function in ischemia-injured porcine ileum}, volume={127}, ISSN={["1528-0012"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4444353665&partnerID=MN8TOARS}, DOI={10.1053/j.gastro.2004.06.004}, abstractNote={BACKGROUND & AIMS
Ischemia results in the breakdown of the intestinal barrier, predisposing patients to sepsis and multiple organ failure. Prostaglandins play a critical role in mediating recovery of barrier function in ischemia-injured intestine through a mechanism involving stimulation of Cl - secretion. In the present study, we investigated the contributory role of individual Cl - channels in the recovery of barrier function in ischemia-injured porcine ileum.


METHODS
Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers. Short-circuit current (Isc) and transepithelial resistance (TER) were measured in response to prostaglandin E 2 (PGE 2 ) and pharmacologic inhibitors of epithelial Cl - channels. Immunoassays were used to assess the expression and localization of ion channels.


RESULTS
Application of PGE 2 to ischemia-injured ileal mucosa stimulated increases in Isc, an indicator of Cl - secretion, that was followed by marked increases in TER, an indicator of barrier function recovery. In vitro studies revealed that although PGE 2 induced Cl - secretion via at least 3 distinct secretory pathways, recovery of barrier function was initiated by Cl - secretion via ClC-2 Cl - channels co-expressed with occludin and localized to tight junctions within restituting epithelium. Intravenous administration of furosemide to pigs subjected to 1 hour of ileal ischemia impaired recovery of barrier function, as evidenced by decreased TER and increased mucosal-to-serosal 3 H-mannitol flux after a 2-hour reperfusion/recovery period, confirming an important role for Cl - secretory pathways in vivo.


CONCLUSIONS
ClC-2-mediated intestinal Cl - secretion restores TER in ischemia-injured intestine. These data may provide the basis for targeted pharmacologic therapy for diseases associated with impaired barrier function.}, number={3}, journal={GASTROENTEROLOGY}, author={Moeser, AJ and Haskell, MM and Shifflett, DE and Little, D and Schultz, BD and Blikslager, AT}, year={2004}, month={Sep}, pages={802–815} }
 @article{shifflett_bottone_young_moeser_jones_blikslager_2004, title={Neutrophils augment recovery of porcine ischemia-injured ileal mucosa by an IL-1β- and COX-2-dependent mechanism}, volume={287}, ISSN={0193-1857 1522-1547}, url={http://dx.doi.org/10.1152/ajpgi.00076.2003}, DOI={10.1152/ajpgi.00076.2003}, abstractNote={Polymorphonuclear neutrophils (PMNs) play a critical role in intestinal mucosal injury and repair. To study effects of PMNs on acutely injured mucosa, we applied PMNs isolated from circulation or peritoneal fluid from animals with chemically induced peritonitis to ischemia-injured porcine ileal mucosa. In preliminary experiments, PMNs enhanced recovery of transepithelial electrical resistance (TER), and this action was inhibited by pretreatment with the nonselective cyclooxygenase (COX) inhibitor indomethacin. Because COX-2 is upregulated by inflammatory mediators such as IL-1β, which is released by PMNs, we postulated that PMNs enhance recovery of ischemia-injured mucosa by a pathway involving IL-1β and COX-2. Application of 5 × 106PMNs to the serosal surface of ischemia-injured mucosa significantly enhanced recovery of TER ( P < 0.05), an effect that was inhibited by the selective COX-2 inhibitor NS-398 (5 μM) and by an IL-1β receptor antagonist (0.1 mg/ml). Addition of 10 ng/ml IL-1β to the serosal surface of injured tissues caused a significant increase in TER ( P < 0.05) that was inhibited by pretreatment with NS-398. Western blot analysis of mucosal homogenates revealed dramatic upregulation of COX-2 in response to IL-1β or peritoneal PMNs, and the latter was inhibited by an IL-1β receptor antagonist. Real-time PCR revealed that increased mRNA COX-2 expression preceded increased COX-2 protein expression in response to IL-1β. We concluded that PMNs augment recovery of TER in ischemia-injured ileal mucosa via IL-1β-dependent upregulation of COX-2.}, number={1}, journal={American Journal of Physiology-Gastrointestinal and Liver Physiology}, publisher={American Physiological Society}, author={Shifflett, Donnie E. and Bottone, Frank G., Jr. and Young, Karen M. and Moeser, Adam J. and Jones, Samuel L. and Blikslager, Anthony T.}, year={2004}, month={Jul}, pages={G50–G57} }
 @article{campbell_ruaux_shifflett_steiner_williams_blikslager_2004, title={Physiological concentrations of bile salts inhibit recovery of ischemic-injured porcine ileum}, volume={287}, ISSN={0193-1857 1522-1547}, url={http://dx.doi.org/10.1152/ajpgi.00310.2003}, DOI={10.1152/ajpgi.00310.2003}, abstractNote={We have previously shown rapid in vitro recovery of barrier function in porcine ischemic-injured ileal mucosa, attributable principally to reductions in paracellular permeability. However, these experiments did not take into account the effects of luminal contents, such as bile salts. Therefore, the objective of this study was to evaluate the role of physiological concentrations of deoxycholic acid in recovery of mucosal barrier function. Porcine ileum was subjected to 45 min of ischemia, after which mucosa was mounted in Ussing chambers and exposed to varying concentrations of deoxycholic acid. The ischemic episode resulted in significant reductions in transepithelial electrical resistance (TER), which recovered to control levels of TER within 120 min, associated with significant reductions in mucosal-to-serosal3H-labeled mannitol flux. However, treatment of ischemic-injured tissues with 10−5M deoxycholic acid significantly inhibited recovery of TER with significant increases in mucosal-to-serosal3H-labeled mannitol flux, whereas 10−6M deoxycholic acid had no effect. Histological evaluation at 120 min revealed complete restitution regardless of treatment, indicating that the breakdown in barrier function was due to changes in paracellular permeability. Similar effects were noted with the application of 10−5M taurodeoxycholic acid, and the effects of deoxycholic acid were reversed with application of the Ca2+-mobilizing agent thapsigargin. Deoxycholic acid at physiological concentrations significantly impairs recovery of epithelial barrier function by an effect on paracellular pathways, and these effects appear to be Ca2+dependent.}, number={2}, journal={American Journal of Physiology-Gastrointestinal and Liver Physiology}, publisher={American Physiological Society}, author={Campbell, Nigel B. and Ruaux, Craig G. and Shifflett, Donnie E. and Steiner, Jöerg M. and Williams, David A. and Blikslager, Anthony T.}, year={2004}, month={Aug}, pages={G399–G407} }