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Newly Described Processes Limit Post-Ischemia Epithelial Damage

Lamina propria contraction and epithelial constriction preserves gut epithelium post ischemia

MONDAY, June 20 (HealthDay News) -- The epithelial lining of human jejunum is preserved during intestinal ischemia-reperfusion (IR) by rapid lamina propria contraction and zipper-like constriction of epithelial cells before they are shed into the lumen, according to a study published in the July issue of the Journal of Pathology.

Joep Grootjans, M.D., from the Maastricht University Medical Centre in the Netherlands, and colleagues investigated the mechanisms by which the human gut limits epithelial lining damage caused by IR. In 10 patients, a part of the jejunum that was to be removed for surgical reasons was selectively exposed to IR over 150 minutes. Tissue was exposed to 30 minutes of ischemia with a reperfusion of zero, 30, or 120 minutes, and was analyzed along with control tissue.

The investigators found that, after 30 minutes of ischemia, the epithelial lining remained intact with subepithelial spaces on hematoxylin/eosin staining. Western blot analysis showed a significant increase in myosin light chain kinase (MLCK) protein levels, and MLCK and phosphorylated MLC (pMLC) in lamina propria fibers after ischemia. Early in reperfusion, pMLC accumulation was seen exclusively at the basal side of enterocytes that had lost contact with the basement membrane. Even before cells were shed, these epithelial sheets were pulled together like a zipper. This constriction was verified by increased double staining of F-actin and pMLC, and it accounted for a significant (45 percent) reduction in the virtual wound surface area at 30 minutes of reperfusion, and full epithelial lining restoration within 120 minutes of reperfusion.

"Human jejunum has the ability to preserve the epithelial lining during intestinal IR by rapid lamina propria contraction and zipper-like constriction of epithelial cells that are to be shed into the lumen," the authors write.

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