Intestinal and systemic illnesses have been linked to increased gut permeability. Bile acids, whose luminal profile can be altered in human disease, modulate intestinal paracellular permeability. We investigated the mechanism by which selected bile acids increase gut permeability using a validated in vitro model. Human intestinal Caco-2 cells were grown in monolayers and challenged with a panel of bile acids. Transepithelial electrical resistance and luminal-to-basolateral fluxes of 10-kDa Cascade blue-conjugated dextran were used to monitor paracellular permeability. Immunoprecipitation and immunoblot analyses were employed to investigate the intracellular pathway. Redistribution of tight junction proteins was studied by confocal laser microscopy. Micromolar concentrations of cholic acid, deoxycholic acid (DCA), and chenodeoxycholic acid (CDCA) but not ursodeoxycholic acid decreased transepithelial electrical resistance and increased dextran flux in a reversible fashion. Coincubation of 50 muM CDCA or DCA with EGF, anti-EGF monoclonal antibody, or specific src inhibitor 4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP-2) abolished the effect. A concentration of 50 muM of either CDCA or DCA also induced EGF receptor phosphorylation, occludin dephosphorylation, and occludin redistribution at the tight junction level in the same time frame and in a reversible fashion. We conclude that selected bile acids modulate intestinal permeability via EGF receptor autophosphorylation, occludin dephosphorylation, and rearrangement at the tight junction level. The effect is mediated by the src family kinases and is abolished by EGF treatment. These data also support the role of bile acids in the genesis of necrotizing enterocolitis and the protective effect of EGF treatment.

Our data show that Avena genziana and Avena potenza do not display in vitro activities related to CD pathogenesis. Some T-cell reactivity could be below the threshold for clinical relevance.

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The ecological management effectiveness (EME) of Marine Protected Areas (MPAs) is the degree to which MPAs reach their ecological goals. The significant variability of EME among MPAs has been partly explained by MPA design, management and implementation features (e.g. surface area, enforcement, age of protection). We investigated EME variability by employing, for the first time, Organization Science. Eight Mediterranean MPAs were taken into account as case studies to explore the relationships between EME and MPA features, such as: 1) organizational size (i.e. the ratio between the number of full-time employees and the total MPA surface area), 2) management performance (i.e. the level of effort exerted to enhance and sustain the MPA management, including enforcement), 3) total surface area, and 4) MPA age. The log-response ratios of fish biomass and density in protected vs unprotected (control) areas were used as a proxy of EME. Management performance, organizational size and, to a lesser extent, MPA age were positively correlated with the log-response ratio of fish biomass, whereas total surface area did not display a significant role. None of the four features considered was significantly correlated with the log-response ratio of fish density. Based on our findings, we argue that the employment of Organization Science in the management effectiveness assessment can assist MPA managers to reach MPAs goals more effectively, with a more efficient use of available resources.

Unconjugated bilirubin promotes intestinal secretion without affecting nutrient digestion or absorption. In the current study, the effects of unconjugated bilirubin (UCB) on the barrier function of the intestinal epithelium were investigated. The apical side of human intestinal cell line Caco-2 monolayers was challenged with purified UCB. Transepithelial electrical resistance and paracellular fluxes of 10 kD Cascade blue conjugate dextran were measured. Cell monolayer viability was studied using LDH release and trypan blue exclusion tests. Redistribution of enterocyte tight junction occludin was studied by confocal microscopy. Bilirubin induced a dose-dependent decrease of transepithelial electrical resistance (TEER). This effect was maximal at 6 h and tended to be reversed at 48 h. Oxidated bilirubin was ineffective. Bilirubin significantly increased fluorescent dextran paracellular passage. Cell viability was not affected by UCB over the 5-200 nmol/L concentration range. H yperbilirubinemia is a common finding in both term and preterm neonates (1). Because bilirubin can cause severe damage to the central nervous system, most investigators have focused their research on its effects on neural cells (2). The interaction of bilirubin with other organs has also been explored, although to a lesser extent. In the intestine, for example, bilirubin is excreted with bile in the gut lumen mainly as mono or diglicuronides. However, the enzyme glycuronidase, of both endogenous and microbial origin, partially converts it to UCB (3). Previous reports have shown UCB concentrations in the intestinal lumen of hyperbilirubinemic newborns to be in the micromolar range (4,5). Investigators have also documented that UCB in the gut does not affect cell viability, nutrient absorption, or brush border enzyme activities, although it can induce watery diarrhea by direct stimulation of ion secretion (6,7). Jaehrig et al. (8) found that UCB transit in the intestinal lumen of the human newborn was associated with a decreased transmural potential difference. As the latter is an indirect measurement of the tightness of the intestinal barrier, they suggested that bilirubin could cause "some injury" to the intestinal fence by increasing its permeability. This is of potential clinical interest because a decrease in the gut barrier function has been linked to the pathogenesis of intestinal (i.e. necrotizing enterocolitis) diseases (9) and extraintestinal, particularly allergic and autoimmune, disorders (10,11). The aim of this study was to further investigate in vitro the effect of bilirubin on intestinal epithelial permeability. For this purpose, we have used monolayers of the well-established human transformed cell line Caco-2 that displays many biologic features of the primary intestinal epithelium (12,13). The study was approved by the Institutional Review Board of the "Facoltà di Medicina-Federico II." MATERIALS AND METHODSReagents. Cell culture chemicals were obtained from GIBCO-Life Technologies (Milan, Italy). 10 kD Cascade blu...