Hepatocyte tight-junctional permeability is increased in rat experimental colitis.

Hepatobiliary complications occur in inflammatory bowel disease and may be caused by the translocation of intestinal toxins from portal blood into bile through leaky hepatocyte tight junctions. The role of tight junctions in the pathogenesis of hepatobiliary complications in experimental inflammatory bowel disease was investigated. Colitis was induced in rats by intracolonic instillation of trinitrobenzene sulfonic acid. The function of hepatocellular tight junctions was evaluated in perfused livers by measuring early (paracellular) horseradish peroxidase excretion into the bile and by electron microscopy and semiquantitative analysis of lanthanum penetration through the tight junction and into bile canaliculi. Immunofluorescent localization of cingulin and ZO-1 was used to study the structure of hepatocyte junctions. Colitis was associated with increased serum bilirubin and bile acid concentrations, a 2.5-fold increase in paracellular biliary excretion of horseradish peroxidase, and a ninefold increase in lanthanum permeability. Liver histology and cingulin and ZO-1 localizations were similar to normal liver. Experimental colitis is associated with hepatobiliary complications and an increased hepatocyte tight junctional permeability to horseradish peroxidase and lanthanum. Subtle alterations in tight junction function may be involved in the pathogenesis of hepatobiliary injuries in inflammatory bowel disease.

Lora L ，Mazzon E ，Martines D ，Fries W ，Muraca M ，Martin A ，d'Odorico A ，Naccarato R ，Citi S ... -  《GASTROENTEROLOGY》

Role of IL-10 in hepatocyte tight junction alteration in mouse model of experimental colitis.

A variety of hepatobiliary abnormalities have been described in patients with chronic inflammatory bowel diseases (IBDs). The purpose of this study was to investigate the role of endogenous IL-10 in alteration of hepatocyte TJ paracellular barrier and in the rapid transcytotic vesicular pathway modification associated with intestinal inflammation. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated IL-10 wild-type (IL-10WT) mice, DNBS-treated IL-10 knock-out mice (IL-10KO) mice experienced a higher rate of the extent and severity of the histological signs of colon injury. Colon and liver levels of the pro-inflammatory cytokines tumour necrosis factor, interleukin-1 beta and interleukin-6 were also greatly enhanced in IL-10KO mice in comparison to wild-type mice. Liver histology from IL-10KO and IL-10WT did not show any parenchymal and portal tract inflammation at 4 days after DNBS administration. Serum total bilirubin and Alanine aminotransferase, were significantly increased in DNBS-IL-10KO mice vs. DNBS-IL-10KO mice. Therefore, we found an increase of tight junctional permeability to lanthanum nitrate (molecular weight, 433) in the livers from DNBS-treated IL-10WT mice; lanthanum accumulated throughout the junctional area up to the most apical region bordering the lumen. Absence of a functional IL-10 gene in IL-10KO mice resulted in a significant augmentation of apical diffusion of lanthanum after DNBS-induced colitis. Immunofluorescent labelling of frozen liver sections from DNBS-IL10KO mice, immunolocalization for and claudin-1 and ZO-1 resulted in a significant alteration in the localization of the immunosignals for claudin-1 and ZO-1 after DNBS administration in comparison with DNBS-IL10WT. In conclusion, we suggest that the absence of IL-10 may represent an important pathophysiological mechanism of hepatobiliary injuries and cholestasis observed in patients with IBD.

Mazzon E ，Puzzolo D ，Caputi AP ，Cuzzocrea S ... -  《-》

Role of iNOS in hepatocyte tight junction alteration in mouse model of experimental colitis.

A variety of hepatobiliary abnormalities occur in inflammatory bowel diseases (IBDs). The role of tight junction (TJ) in hepatobiliary complications have been well described. The purpose of this study was to investigate the role of inducible nitric oxide (NOS) in alteration of hepatocyte TJ paracellular barrier and in the rapid transcytotic vesicular pathway modification associated with intestinal inflammation. To address this question, we used an experimental model of colitis, induced by dinitrobenzene sulfonic acid (DNBS). When compared to DNBS-treated iNOS wild-type (WT) mice, DNBS-treated iNOS knock out mice (iNOSKO) mice experienced a significant less rate of the extent and severity of the histological signs of colon injury. Colon levels of the pro-inflammatory cytokines tumour necrosis factor, interleukin-1beta and interleukin-6 were also significantly reduced in iNOS-KO mice in comparison to wild-type mice. Liver histology from iNOSKO and wild-type mice iNOSWT did not show any parenchymal and portal tract inflammation at 4 days after DNBS administration. Serum total bilirubin and alanine aminotransferase, were significantly reduced in DNBS-iNOSKO mice vs DNBS-iNOSKO mice. Therefore, we found an increase of tight junctional permeability to lanthanum nitrate (molecular weight, 433) in the livers from DNBS-treated IL-10WT mice, lanthanum accumulated throughout the junctional area up to the most apical region bordering the lumen. Absence of a functional iNOS gene in iNOSKO mice resulted in a significant reduction of apical diffusion of lanthanum after DNBS-induced colitis. Immunofluorescent labeling of frozen liver sections from DNBS-iNOSWT mice showed a significant alteration of the immunolocalization for claudin-1 and zonula occludens (ZO)-1. In contrast, a significant reduced alteration in the localization of the immunosignals for claudin-1 and ZO-1 was observed in the liver from iNOSKO mice after DNBS administration. In conclusion, we suggest that the iNOS may represent an important pathophysiological mechanism of hepatobiliary injuries and cholestasis observed in patients with IBD.

Mazzon E ，Cuzzocrea S 《CELLULAR AND MOLECULAR BIOLOGY》

Cholestasis with altered structure and function of hepatocyte tight junction and decreased expression of canalicular multispecific organic anion transporter in a rat model of colitis.

Kawaguchi T ，Sakisaka S ，Mitsuyama K ，Harada M ，Koga H ，Taniguchi E ，Sasatomi K ，Kimura R ，Ueno T ，Sawada N ，Mori M ，Sata M ... -  《HEPATOLOGY》

Effects of cyclosporin A on paracellular and transcellular transport of horseradish peroxidase in perfused rat livers.

Lora L ，Mazzon E ，Billington D ，Milanesi C ，Naccarato R ，Martines D ... -  《DIGESTIVE DISEASES AND SCIENCES》