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Excessive intrahepatic accumulation of bile acids (BAs) is a key mechanism underlying cholestasis. The aim of this study was to quantitatively explore the relationship between cytotoxicity of BAs and their intracellular accumulation in sandwich-cultured rat hepatocytes (SCRH). Following exposure of SCRH (on day-1 after seeding) to various BAs for 24h, glycine-conjugated BAs were most potent in exerting toxicity. Moreover, unconjugated BAs showed significantly higher toxicity in day-1 compared to day-3 SCRH. When day-1/-3 SCRH were exposed (0.5-4 h) to 5-100 μM (C)DCA, intracellular levels of unconjugated (C)DCA were similar, while intracellular levels of glycine conjugates were up to 4-fold lower in day-3 compared to day-1 SCRH. Sinusoidal efflux was by far the predominant efflux pathway of conjugated BAs both in day-1 and day-3 SCRH, while canalicular BA efflux showed substantial interbatch variability. After 4h exposure to (C)DCA, intracellular glycine conjugate levels were at least 10-fold higher than taurine conjugate levels. Taken together, reduced BA conjugate formation in day-3 SCRH results in lower intracellular glycine conjugate concentrations, explaining decreased toxicity of (C)DCA in day-3 versus day-1 SCRH. Our data provide for the first time a direct link between BA toxicity and glycine conjugate exposure in SCRH. publisher: Elsevier articletitle: Toxicity and intracellular accumulation of bile acids in sandwich-cultured rat hepatocytes: Role of glycine conjugates journaltitle: Toxicology in Vitro articlelink: http://dx.doi.org/10.1016/j.tiv.2013.10.020 content_type: article copyright: Copyright © 2013 Elsevier Ltd. All rights reserved. ispartof: Toxicology in Vitro vol:28 issue:2 pages:218-230 ispartof: location:England status: published

A Functional Variant of the Farnesoid X Receptor (FXR) Predisposes to Ileocolonic Localization of Crohn's Disease Rian M. Nijmeijer, Raffaella Maria Gadaleta, Karel J. Van Erpecum, Adriaan A. van Bodegraven, J. Bart A. Crusius, Gerard Dijkstra, Daniel W. Hommes, Dirk J. De Jong, Cyriel Ponsioen, Hein W. Verspaget, Rinse K. Weersma, Christien J. van der Woude, Marguerite E. Schipper, Cisca Wijmenga, Saskia W. van Mil, Bas Oldenburg

In 17 patients GC samples were reevaluated for histological characteristics, 14 were MSIH and 3 failed in MSI testing, however IHC stainings for the affected MMR protein were negative in all these patients. Six (35%), 4 (23%) and 7 (41%) GC samples showed intestinal type, diffuse type and mixed type characteristics respectively. In 13 GC samples, the tissue surrounding GC could be evaluated. Intestinal metaplasia was diagnosed in 5 (38%) samples and atrophic gastritis in 2 (15%) samples. Pre-malignant gastric lesions were evenly distributed throughout intestinal, diffuse and mixed type gastric cancer samples (p=0.40). Conclusions: This study demonstrates that GC develops along similar histopathologic pathways as sporadic gastric cancer in LS. Pre-malignant lesions in tissue surrounding GC were evident in >50% of samples. These data support upper GI surveillance endoscopy in LS subjects.

The bile salt nuclear receptor Farnesoid X Receptor (FXR) was recently implicated in intestinal antibacterial defense and barrier function. We aimed to study its role in pathogenesis of inflammatory bowel diseasE. colitis was induced in Wild Type (WT) and FXR knock-out (ko) mice (n=8 to 10 for each group) by Dextran Sodium Sulphate (DSS: 2.5% in drinking water, 10 days) with or without synthetic FXR ligand 6-Ethyl Chenodeoxycholic Acid (6ECDCA: 5 mg/kg/day, 13 days, starting 3 days before DSS). Colitis symptoms were checked daily and intestinal permeability (FITC-dextran assay), bile salt composition (HPLC), histology and colonic inflammatory gene expression (Q-PCR) determined. mRNA expression of FXR and target genes was determined in IBD patient biopsies. Underlying mechanisms were explored in complementary In Vitro experiments. 6ECDCA-treated WT but not FXR ko mice were protected from DSS-induced colitis, as shown by highly significant reduction of body weight loss, rectal bleeding, colonic shortening, normalization of intestinal permeability, 49% reduction in blinded histological score and 55% reduction in goblet cell loss. Only in 6ECDCA-treated WT mice, mRNA levels of pro-inflammatory genes (IL-1β, IL-6, IL10 and MCP-1) were strongly down-regulated while antibacterial defense gene iNOS was upregulated. 6ECDCA was enriched in bile of both WT and FXR ko mice (9.8% and 5.3% of total bile salts, respectively). However intestinal expression of FXR target genes FGF15 and SHP was increased 4.5and 19-fold with 6ECDCA treatment only in WT. In patients with quiescent Crohn colitis (n=17), mRNA expression of FXR and SHP was significantly altered compared to patients with ulcerative colitis (n=16) or healthy controls (n=17). In differentiated CaCo2 cells grown on trans-well plates, FXR activation by GW4064 prevented DSS-dependent loss of integrity of the monolayer. In differentiated HT29 cells, TNFαinduced 20-fold increase of IL-1β expression was abolished by GW4064-dependent FXR activation. In reporter assays, the FXR agonist GW4064 prevented TNFα-induced NF-κB activity in HEK293 cells transfected with WT FXR, but no effect was achieved with FXR mutant W469A (defective in Ligand Binding Domain), indicating FXR-mediated inhibition of NF-κB signalling. In conclusion, FXR activation protects against experimental murine colitis, supposedly by preserving the intestinal barrier and inhibitingNF-κB activity. Currently available potent synthetic FXR agonists may offer new therapeutic strategies for inflammatory bowel disease.