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Jnk1 in murine hepatic stellate cells is a crucial mediator of liver fibrogenesis

ABSTRACT: Hepatic fibrosis is a wound-healing response to chronic liver injury, which may result in cirrhosis and liver failure. The c-Jun N-terminal kinase-1 (JNK1) gene has been shown to be involved in liver fibrosis. Here, we aimed to investigate the molecular mechanism and identify the cell-type involved in mediating the JNK1-dependent effect on liver fibrogenesis Wild-type (WT), JNK1−/− and JNK1Δhepa (hepatocyte-specific deletion of JNK1) mice were subjected to bile duct ligation (BDL). Additionally, we performed bone marrow transplantations (BMT), isolated primary hepatic stellate cells (HSCs) and studied their activation in vitro. Serum markers of liver damage (liver transaminases, alkaline phosphatase and bilirubin) and liver histology revealed reduced injury in JNK1−/− compared to WT and JNK1Δhepa mice. Hepatocyte cell death and proliferation was reduced in JNK1−/− compared to WT and JNK1Δhepa. Parameters of liver fibrosis such as Sirius Red staining as well as Collagen IA1 and αSMA expression were down-regulated in JNK1−/− compared to WT and JNK1Δhepa livers, 4 weeks after BDL. To delineate the essential cell-type, we performed BMT of WT and JNK1-/- into JNK1-/- and WT mice, respectively. BMT experiments excluded bone marrow derived cells from having a major impact on the JNK1-dependent effect on fibrogenesis. Hence, we investigated primary HSCs from JNK1−/− livers showing reduced transdifferentiation compared with WT and JNK1Δhepa-derived HSCs. We conclude that JNK1 in HSCs plays a crucial role in hepatic fibrogenesis and thus represents a promising target for cell-directed treatment options for liver fibrosis.

ORGANISM(S): Mus musculus

PROVIDER: GSE40041 | GEO | 2013/11/27

SECONDARY ACCESSION(S): PRJNA172763

REPOSITORIES: GEO

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Project description:Gene-expression profiles of hepatic stellate cells isolated from IL15R-alpha knockout mouse IL-15 and its high affinity receptor IL-15Rα are widely expressed in immune cells including dendritic cells and macrophages and non-immune cells such as hepatocytes, oval cells and hepatic stellate cells (HSC). IL-15 signaling has important functions in natural killers (NK), natural killers T (NKT) and cytotoxic T (CD8+T) cell homeostasis and also in liver regeneration. We hypothesized that IL-15 may have a protective role during liver fibrosis progression due to its role in NK cell homeostasis. We compared fibrosis progression in IL-15Rα knockout mice (IL-15RαKO) to wild type mice using two mechanistically distinct models, chronic carbon tetrachloride (CCl4) exposure and bile duct ligation (BDL). Enhanced fibrosis progression was observed in IL-15RαKO mice in both models. Furthermore, using congenic bone marrow transplantation (BMT), we demonstrated an unexpected role for IL-15 signaling in hepatic resident cells for the maintenance of liver NK and CD8+T cell populations. Using this approach, transplanting IL-15RKO hematopoietic cells results in NK defect that surprisingly is not reflected in a change of fibrosis progression. However, chimeric mice with defect of IL-15R on liver resident cells have similar NK defects and significant more fibrosis after CCL4 liver injury. This supports a direct protective, anti-fibrogenic role for IL-15R on one of the radioresistant liver cell populations (hepatocytes, HSC and sessile Kupffer cells). Microarray analysis of IL15RKO HSC suggests up-regulation of collagen transcripts and down-regulation of pathways involved in cell proliferation/survival. Finally, activated HSCs isolated from IL-15RKO mice show increased collagen secretion and as predicted, no changes in the growth curves. In summary, IL-15Rα signaling has an anti-fibrotic effect through both BM-derived and hepatic resident cells. These findings establish a rationale to explore IL-15 signaling in HSC as a potential therapeutic target in liver fibrogenesis.

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Jnk1 in murine hepatic stellate cells is a crucial mediator of liver fibrogenesis

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