Z Gastroenterol 2011; 49 - V86
DOI: 10.1055/s-0031-1285222

TNF-receptor 1 ameliorates disease progression of Nemo-mediated hepatitis

A Singh 1, FJ Cubero 1, E Borkham-Kamphorst 2, M Boekschoten 3, M Al-Masaoudi 1, C Liedtke 1, T Luedde 1, R Weiskirchen 2, M Müller 3, M Heikenwälder 4, C Trautwein 1
  • 1Department of Internal Medicine III, University Hospital Aachen (RWTH), Aachen, Germany
  • 2Institut für Klinische Chemie und Pathobiochemie, University Hospital Aachen (RWTH), Aachen, Germany
  • 3University of Wageningen, Department of Human Nutrition, Wageningen, Netherlands
  • 4Institute of Virology TU Munich, München, Germany

Hepatocyte-specific NEMO knockout mice (NemoΔhepa) show that the IκB kinase subunit NEMO/IKKγ is essential for activating NF-κB, which regulates cellular responses during inflammation, cell proliferation and apoptosis. In the present study we aimed to better characterise the protective pathways in death receptor-mediated hepatocyte apoptosis in NemoΔhepa animals. We thus established NemoΔhepaTRAIL-/-, NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- and analyzed its consequences on disease progression compared to NemoΔhepa animals.

NemoΔhepaTRAIL-/- like NemoΔhepa mice showed increased apoptosis, proliferation, steatohepatitis, fibrosis, and the appearance of first liver nodules at 8 weeks which was ameliorated in NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- livers. Hepatocyte apoptosis was significantly increased in NemoΔhepa and NemoΔhepaTRAIL-/- mice while NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- animals showed reduced apoptotic and unchanged necrotic cell death. This phenotype was accompanied by a strong reduction in pJNK levels in NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- compared with NemoΔhepa and NemoΔhepaTRAIL-/- mice. Additionally, cell cycle parameters e.g. Cyclin A, Cyclin D and p21 were significantly less activated in NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- livers. Interestingly also fibrosis parameters (a1a collagen and aSMA) were significantly decreased in these animals. These results were further confirmed by Microarray analysis which proved our concept that NemoΔhepaTNFR1-/- has less fibrosis, decreased acute phase response, less hepatic cholestasis, decreased death receptor signalling molecule which are involved apoptosis and fatty acid signalling pathways. To further support the functional role of TNFR1 signalling in NemoΔhepa animals, we performed LPS stimulation experiments. Here NemoΔhepaTNFR1-/- and NemoΔhepaTRAIL-/-TNFR1-/- animals were protected, while both NemoΔhepa and NemoΔhepaTRAIL-/- animals were hypersensitive to the challenge as evidenced by transaminase levels and markers of apoptosis.

Our present data using double and triple knockout animals demonstrate that the death receptor TNFR1 in contrast to TRAIL is essential in determining hepatitis progression in NemoΔhepa animals.