| Outcome Measures: |
Secondary Objective: Assess the effect of obeticholic acid (OCA) in patients with PBC [in combination with long-term UDCA treatment (15 mg/kg/d)], patients with NASH and healthy volunteers on the biliary and serum levels of cytokines (e.g., IL-6, IL-8, TNFa), chemokines and enterohepatic hormones (e.g., FGF-19)<br><br>Assess the effect of obeticholic acid (OCA) in patients with PBC [in combination with long-term UDCA treatment (15 mg/kg/d)], patients with NASH and healthy volunteers on the bile acid composition and microbiome in faeces<br><br>Assess the effect of obeticholic acid (OCA) in patients with PBC [in combination with long-term UDCA treatment (15 mg/kg/d)], patients with NASH and healthy volunteers on the expression of duodenal transport proteins and enzymes contributing to the biliary and intestinal detoxification machinery;Main Objective: To explore the exact working mechnism of OCA in PBC / NASH patients in comparison with healthy volunteers --><br><br>Assess the effect of obeticholic acid (OCA) in patients with PBC [in combination with long-term UDCA treatment (15 mg/kg/d)], patients with NASH and healthy volunteers on the bile acid and lipid composition of bile and serum,;Primary end point(s): - Bile acids: Concentrations of UDCA, cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA), glycoursodeoxycholic acid (GUDCA), glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), glycodeoxycholic acid (GDCA), glycolithocholic acid (GLCA), tauroursodeoxycholic acid (TUDCA), taurocholic acid (TCA), taurochenodeoxycholic acid (TCDCA), taurodeoxycholic acid (TDCA), taurolithocholic acid (TLCA) and C4 will be determined in plasma and bile by liquid chromatography tandem mass spectrometry according to the principles of good laboratory practice.<br><br><br>;Timepoint(s) of evaluation of this end point: Day 0, 29/30, day 35Secondary end point(s): - Lipids: The biliary lipid profile will be analyzed (before and 4 weeks after start of treatment with OCA) using a recently developed AMC lipidomics platform which allows to detect and quantify ~1000 different lipids in bile.<br><br>- Cyto- and chemokines and hormones: A panel of 27 cyto- and chemokines will be analyzed in bile after dilution (50-100 fold) using Luminex?? technology (Merck Millipore, Milliplex Map Human Cytokine/Chemokine Panel). IL6, IL8 and TNFa levels in bile will be quantified by ELISA (R&D Systems, #DY-206, #DY-208 and #DY-210). FGF19 levels in bile and serum will be determined by sandwich ELISA; bile samples will be tested for proteolytic activity by spiking with FGF19.<br><br>Serum: CK-18 (a biomarker correlating with hepatocyte apoptosis)<br><br>- Total biliary levels of bile salts, phospholipids and cholesterol will be determined by enzymatic methods. Total bilirubin will be quantified by HPLC.<br><br>- Faeces: microbiome, bile acid composition;Timepoint(s) of evaluation of this end point: Day 0, 29/30, day 35
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