Alterations in the cytoskeleton of enterocytes in Crohn's disease and ulcerative colitis

Abstract

Introduction : Actin filaments are an important component of the cytoskeleton of enterocytes. Regulation of actin polymerization allows cells to control their shape, secrete and phagocytosis. The aim of this study was to analyse the distribution of actin in normal enterocytes (NE) and atypical enterocytes characterized by rapid antigen uptake into the cytosol (RACE) and ultrastructural alterations which have been previously described by our group in Crohn's disease (CD) and ulcerative colitis (UC). Methods: The labeling density (LD) of immunogold binding to antibodies against actin was determined in the terminal web and at the basolateral membrane by immunoelectron microscopy in NE and RACE of CD (n = 5), UC (n = 5) and healthy controls (HC: ileum (ll) n = 5 , colon (Co) n=5) . Statistics: Wilcoxon U-test; P < 0.05 was considered significant. Results: In RACE cells actin filaments seemed to be disassembled and labeling densitiy of actin was sigmficantly reduced relative to NE of CD and UC in the terminal web and at the basolatera[ membrane (P<0.05). Actin labeling of NE in CD and UC did not show any significant difference to HC with the exception of actin labeling at the basolateral membrane of CD, that was sigmficantly reduced relative to HC (P<0.04). Discussion: Alterations in the distribution of actin, that is an important factor for cell stability and transcellular transport processes could be responsible for the increased absorption of antigens in RACE. Due to this RACE may play a key role in the pathogenesis of chronic inflammation in CD and UC.