Objective There is a striking association between human cholestatic liver disease (CLD) and inflammatory bowel disease. However, the functional implications for intestinal microbiota and inflammasome-mediated innate immune response in CLD remain elusive. Here we investigated the functional role of gut–liver crosstalk for CLD in the murine Mdr2 knockout (Mdr2−/−) model resembling human primary sclerosing cholangitis (PSC).
Design Male Mdr2 −/−, Mdr2−/− crossed with hepatocyte-specific deletion of caspase-8 (Mdr2−/− /Casp8∆hepa) and wild-type (WT) control mice were housed for 8 or 52 weeks, respectively, to characterise the impact of Mdr2 deletion on liver and gut including 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 experiments.
Results Mdr2−/− mice displayed an unfavourable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut–liver axis. Intestinal dysbiosis in Mdr2−/− mice prompted intestinal barrier dysfunction and increased bacterial translocation amplifying the hepatic NLRP3-mediated innate immune response. Transfer of Mdr2−/− microbiota into healthy WT control mice induced significant liver injury in recipient mice, highlighting the causal role of intestinal dysbiosis for disease progression. Strikingly, IDN-7314 dampened inflammasome activation, ameliorated liver injury, reversed serum bile acid profile and cholestasis-associated microbiota signature.
Conclusions MDR2-associated cholestasis triggers intestinal dysbiosis. In turn, translocation of endotoxin into the portal vein and subsequent NLRP3 inflammasome activation contribute to higher liver injury. This process does not essentially depend on caspase-8 in hepatocytes, but can be blocked by IDN-7314.
- primary sclerosing cholangitis
- cholestatic liver diseases
- gut inflammation
- enteric bacterial microflora
- intestinal barrier function
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LL and KMS contributed equally.
FJC and CT contributed equally.
Contributors LL and KMS: performed most of the experiments, analysed most of the data and drafted the manuscript. MF and HS: contributed to the performance of experiments. EJCG and TS: analysed the microbiota composition. H-UM and AW: performed bile acids analyses. AM: managed the experimental mice. JP: provided technical support. JH: analysed double knock-out mice. JR: contributed to the FITC-dextran detection. MH and HWZ: provided critical revision of the manuscript. TL, JH and PP: analysed liver histology. IB and AN: measured and analysed LPS levels. CL: provided the double knock-out mice data, data interpretation and critically reviewed the manuscript. FJC: supervised and reviewed the study. CT: designed the experiments, supervised the study, drafted the paper and provided funds.
Funding This study was supported by the German Research Foundation TR 285/10‑1 and SFB/TRR 57 to CT; the Federal Ministry of Education and Research (ObiHep grant #01KU1214A to CT); the Liver-LiSyM grant (BMBF) to CT, The HDHL-INTIMIC Di-Mi-Liv to CT and KMS; the SFB 985 project C3 to CT; the Interdisciplinary Centre for Clinical Research (START Grant #691438) within the Faculty of Medicine at RWTH Aachen University, the Deutsche Krebshilfe (project #109988 to CT and CL); the Interdisciplinary Centre for Clinical Research within the faculty of Medicine at the RWTH Aachen University (IZKF E8-2 to CL); the Helmholtz Association (VH-NG-933 to TS); the START-Program of the Faculty of Medicine #691405, RWTH Aachen), i³tm Seed Fund Project SF_15_5_17 (RWTH Aachen), the MINECO Retos SAF2016-78711, EXOHEP-CM S2017/BMD-3727, NanoLiver-CM Y2018/NMT-4949, ERAB Ref. EA 18/14, AMMF 2018/117 and COST Action CA17112 and Ramón y Cajal Fellowship (RYC-2014-15242) to FJC; The Swedish Research Council and the Regional Research Council of Västra Götaland to H-UM; Pudong New Area Health and Family Planning Commission Clinical peak discipline construction (Shanghai, PWYgf2018-05), Natural Science Foundation of Jiangxi Province (S2019ZRMSB2159) to LL
Competing interests None declared.
Ethics approval Approval by the local Animal Care Committees (#AZ84-02.04.2013.A184(CT), #AZ84-02.04.2017.A327(CT), PROEX 195/16 (FJC) and PROEX 210/18 (FJC), respectively.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.