Gut edema alters expression of tight junction proteins

Abstract

Abstract Introduction: We have previously shown that gut edema without ischemia/reperfusion injury increases intestinal permeability in the ileum. Intestinal permeability is regulated by tight junction proteins which control the movement of macromolecules between epithelial cells. The proteins occludin and claudin-1 are the structural components and myosin light chain kinase is the regulatory component of the tight junction which is reinforced by the actin cytoskeleton. We hypothesized that gut edema increases permeability by decreasing expression of tight junction proteins. Methods: At laparotomy, rats were given 80cc/kg of 0.9% saline + superior mesenteric vein partial occlusion (Edema) or sham surgery. At 12 hrs, ileum was harvested for evaluation of occludin, claudin-1, myosin light chain kinase (MLCK) and mature, filamentous actin (F-actin) by deconvolution microscopy. Tissue water was determined using wet to dry weight ratio. Data are expressed as mean +/− SEM, t-test, 4–5/group. Results: Gut edema significantly increased the wet to dry ratio compared to sham and was associated with a significant increase in occludin and claudin-1 protein expression. MLCK protein expression and F-actin were significantly decreased. ∗Wet to dry ratioOccludin (pixel units)Claudin-1 (pixel units)F-actin (pixel units)MLCK (pixel units)Sham3.22 ± 0.092251 ± 291906 ± 211973 ± 1151962 ± 307Edema3.69 ± 0.07∗3786 ± 330∗3356 ± 777∗602 ± 83∗666 ± 113∗∗Denotes a P Conclusions: Gut edema disrupts the cytoskeleton ring by decreasing the presence of mature, filamentous actin. This disruption does not rely on increased expression of MLCK, but may contribute to the increased expression of structural proteins claudin and occludin seen in gut edema.