Conclusion: The in vivo and in vitro results presented here suggest that intestinal flora and microbial-derived factors activate Paneth cells to secrete proangiogenic signalling molecules to increase intestinal and mesenteric angiogenesis. These effects are abrogated in the absence of Paneth cells leading to a decrease in portal hypertension. PS-159 Intestinal dysbiosis fuels liver disease progression via NLRP3 in the Mdr2 -/- mouse model of primary sclerosing cholangitis Lijun Liao 1,2 , Kai Markus Schneider 1 , Galvez Eric 3 , Mick Frissen 1 , Hanns-Ulrich Marschall 4 , Huan Sun 1 , Maximilian Hatting 1 , Annika Wahlström 4 , Johannes Haybäck 5,6 , Philip Puchas 6 , Antje Mohs 1 , Peng Jin 1 , Ina Bergheim 7 , Anika Nier 7 , Julia Hennings 1 , Johanna Reissing 1 , Zimmermann Henning Wolfgang 1 , Thomas Longerich 8 , Till Strowig 3 , Christian Liedtke 1 , Francisco Javier Cubero 1,9 , Christian Trautwein 1 . 1 University Hospital RWTH Aachen, Department of Internal Medicine III, Aachen, Germany; 2 Shanghai East Hospital, Tongji University, Department of Anesthesiology and Pain Management, Shanghai, Germany; 3 Helmholtz Center for Infection Research GmbH, Braunschweig, Germany; 4 Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Gothenburg, Sweden; 5 University of Magdeburg, Department of Pathology, Magdeburg, Germany; 6 Medical University Graz, Department of Pathology, Graz, Austria; 7 University of Vienna, Molecular Nutritional Science Division, Department of Nutritional Sciences, Vienna, Australia; 8 Heidelberg University Hospital, Liver Cancer Center Heidelberg, Heidelberg, Germany; 9 Complutense University School of Medicine, Department of Immunology, Madrid, Spain Email: kai.markus.schneider@gmail.com Background and aims: There is a striking association between human cholestatic liver disease (CLD) and inflammatory bowel disease. However, the implications for intestinal microbiota and inflammasome mediated innate immune response in cholestatic liver disease remain imprecise. Here we investigated the functional role of gut-liver crosstalk for cholestatic liver disease in PSC patients and the murine PSC-model the Mdr2 knockout (Mdr2 -/– ) mice. Method: Mdr2 -/– , Mdr2 -/- crossed with hepatocyte-specific deletion of capsase-8 (Mdr2 -/- /Casp8 Δhepa ) and wildtype (WT) control mice to characterize the impact of Mdr2 deletion on liver and gut including comprehensive bile acid and microbiota profiling. To block caspase activation, a pan-caspase inhibitor (IDN-7314) was administered. Finally, the functional role of Mdr2 -/- associated intestinal dysbiosis was studied by microbiota transfer (FMT) experiments. Results: Mdr2 -/- mice displayed an unfavorable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut-liver axis, as found by immunostaining and western blot analysis in the intestine as well as in the liver. In addition, significant NLRP3 inflammasome activation was found in livers of PSC patients. Intestinal dysbiosis in Mdr2 -/- mice prompted intestinal barrier dysfunction evidenced by reduced colonic mucus layers, reduction of tight junction expression and increased permeability evidenced byan in-vivo FITC-dextran assay. Loss of intestinal barrier integrity and bacterial translocation triggered the hepatic NLRP3 mediated innate immune response and fueled liver disease progression. Strinkingly, Mdr2 -/- microbiota was transmissible to healthy WT mice, urged intestinal barrier impairment and induced significant liver injury in recipient mice, which resembled the inflammatory Mdr2 -/- phenotype characterized by NLRP3 activation within the gut-liver axis. This phenotype could not be rescued by introducing Mdr2 -/- /Casp8 Δhepa indicating that hepatocytic caspase-8 activation is a downstream consequence and dispensable for the inflammatory response. In contrast, caspase inhibition via IDN-7314 dampened inflammasome activation, improved barrier function, ameliorated liver injury, reversed serum bile acid profile and cholestasis associated microbiota signature. Conclusion: CLD in Mdr2 -/- mice triggers intestinal dysbiosis, which is transmissible to healthy WT mice. In turn, translocation of endotoxin into the portal vein and subsequent NLRP3 inflammasome activation as also found in PSC patients contribute to higher liver injury in Mdr2 -/- mice. This process does not essentially depend on hepatocytic caspase-8, but can be blocked by IDN-7314, highlighting the causal role of intestinal dysbiosis and the subsequent innate immune response for disease progression in Mdr2 -/- mice, which might also be relevant in humans. PS-160 miRNA-21 signals through a gut-liver axis to regulate experimental cholestasis André A. Santos 1 , Marta B. Afonso 1 , Ricardo S. Ramiro 2 , Rui E. Castro 1 , Cecília M. P. Rodrigues 1 . 1 iMed.ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Portugal, Cellular Function and Therapeutic Targeting, Lisbon, Portugal; 2 Instituto Gulbenkian de Ciência, Oeiras, Portugal Email: afasantos@ff.ulisboa.pt Background and aims: Gut microbiota plays an important role in gut-liver axis homeostasis. New evidence suggests that endogenous miRNAs, secreted into the intestinal lumen, may modulate gut microbiota function and abundance. For instance, loss of miR-21 alters gut microbiota composition in mice and protects against inflammatory bowel disease. Of note, we previously showed that miR-21 deletion ameliorates liver fibrosis in experimental cholestasis and improves adaptative response to bile acid dysregulation. Here, we aimed to characterize changes occurring in the gut microbiota of miR-21 knockout (miR-21KO) mice after bile duct ligation (BDL). Methods: Three-month old C57BL/6 wild type (WT) and whole body miR-21KO mice were subjected to sham or BDL surgeries. After 3 days, the small intestine was collected for qRT-PCR analysis of intestinal permeability-related genes. Serum was also collected for biochemical analyses. Gut microbiota composition was evaluated by sequencing the 16S rRNA gene V3 region of bacterial DNA from the small intestinal lumen. In co-housing experiments, WT and miR- 21KO animals were housed together for 1 month and then separated into different boxes for an additional month. Results: Our results show that miR-21KO mice are protected against small intestinal dysbiosis induced by BDL. In particular, depletion of miR-21 in mice positively correlated with increased Lactobacillus sp. and diminished Proteobacteria. This effect is independent from the BDL, as miR-21KO co-housed mice display increased relative abundance of Lactobacillus sp. in the small intestine, compared with WT mice. Of note, separated miR-21KO animals showed higher amounts of Lactobacillus sp. when compared with co-housed miR- 21KO. Further, mRNA expression of small intestinal tight junctions (ZO-1, JAM-A and Occludin-1) and stem cell markers (Lgr5 and Olfm4) are decreased in WT mice after BDL but remains unaltered in miR-21KO animals. Finally, miR-21 ablation also correlates with increased FXR mRNA expression in the small intestine, increased bile acid homeostasis and reduced liver injury. Conclusion: Genetic ablation of miR-21 modulates small intestinal permeability and FXR expression, impacting on bile acid production and contributing for improved gut microbiota and host homeostasis. These results reinforce the importance of the gut-liver axis in protecting the liver after acute cholestasis. Supported by PTDC/BIM-MEC/089572014 and SFRH/BPD/114924/ 2016 from FCT, Portugal. ORAL PRESENTATIONS e100 Journal of Hepatology 2019 vol. 70 | e81–e132