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The Nrf2 signaling pathway prevents cancer initiation, but genetic mutations that activate this pathway are found in various types of cancer. The molecular mechanisms underlying this Janus-headed character are still not understood. Here, we show that sustained Nrf2 activation induces proliferation and dedifferentiation of a Wnt-responsive perivenular hepatic progenitor cell population, transforming them into metastatic cancer cells. The neoplastic lesions display many histological features known from human hepatoblastoma. We describe an Nrf2-induced upregulation of β-catenin expression and its activation as the underlying mechanism for the observed malignant transformation. Thus, we have identified the Nrf2-β-catenin axis promoting proliferation of hepatic stem cells and triggering tumorigenesis. These findings support the concept that different functional levels of Nrf2 control both the protection against various toxins as well as liver regeneration by activating hepatic stem cells. Activation of the hepatic stem cell compartment confers the observation that unbridled Nrf2 activation may trigger tumorigenesis.

International audience; Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown aetiology for which there are no approved therapeutic options. Patients with PSC display changes in gut microbiota and in bile acid (BA) composition; however, the contribution of these alterations to disease pathogenesis remains controversial. Here we identify a role for microbiota-dependent changes in BA synthesis that modulates PSC pathophysiology. In a genetic mouse model of PSC, we show that loss of microbiota-mediated negative feedback control of BA synthesis results in increased hepatic BA concentrations, disruption of bile duct barrier function and, consequently, fatal liver injury. We further show that these changes are dependent on decreased BA signalling to the farnesoid X receptor, which modulates the activity of the rate-limiting enzyme in BA synthesis, CYP7A1. Moreover, patients with advanced stages of PSC show suppressed BA synthesis as measured by serum C4 levels, which is associated with poor disease prognosis. Our preclinical data highlight the microbiota-dependent dynamics of BA metabolism in cholestatic liver disease, which could be important for future therapies targeting BA and gut microbiome interactions, and identify C4 as a potential biomarker to functionally stratify patients with PSC and predict disease outcomes.

Although infection with the human enteropathogen

Sepsis represents a major health problem worldwide because of high mortality rates and cost-intensive therapy. Immunomodulatory strategies as a means of controlling overshooting inflammatory responses during sepsis have thus far not been effective, and there is a general paucity of new therapies. Regulatory immune cells have been shown to play important roles in limiting systemic inflammation. However, the signals inducing a regulatory phenotype in myeloid cells during infection are unknown. Here, we report that myeloid cell-intrinsic glycoprotein 130 (gp130) signals constitute a critical element for immune homeostasis during polymicrobial sepsis. We identify an essential role for gp130 signaling in myeloid cells during M2 macrophage polarization in vitro and in vivo. Myeloid cell-specific deletion of gp130 signaling leads to a defective M2 macrophage polarization followed by exacerbated inflammatory responses and increased mortality during sepsis. These data provide new insights into the molecular basis of M1 and M2 phenotypic dichotomy and identify gp130 as a key regulator of immune homeostasis during sepsis. Our study highlights the Janus-faced role of IL-6 family cytokines during inflammation, which may explain the failure of IL-6-targeted anti-inflammatory approaches in the treatment of sepsis.-Sackett, S. D., Otto, T., Mohs, A., Sander, L. E., Strauch, S., Streetz, K. L., Kroy, D. C., Trautwein, C. Myeloid cells require gp130 signaling for protective anti-inflammatory functions during sepsis.

ObjectiveThere 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).DesignMaleMdr2−/−,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 ofMdr2−/−-associated intestinal dysbiosis was studied by microbiota transfer experiments.ResultsMdr2−/−mice displayed an unfavourable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut–liver axis. Intestinal dysbiosis inMdr2−/−mice prompted intestinal barrier dysfunction and increased bacterial translocation amplifying the hepatic NLRP3-mediated innate immune response. Transfer ofMdr2−/−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.ConclusionsMDR2-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.

Chronic liver injury triggers liver fibrosis and hepatocellular carcinoma (HCC) the third leading cause of cancer-related mortality. Cyclin E1 (CcnE1, formerly designated Cyclin E) is a regulatory subunit of the Cyclin-dependent kinase 2 (CDK2). It is overexpressed in approximately 70 % of human HCCs correlating with poor prognosis, while the relevance of its orthologue Cyclin E2 (CcnE2) is unclear. Hepatocyte-specific deletion of NF-kappa-B essential modulator (NEMO(∆hepa)) leads to chronic hepatitis, liver fibrosis and HCC as well as CcnE up-regulation. To this end, we generated NEMO(∆hepa)/CcnE1(−/−) and NEMO(∆hepa)/CcnE2(−/−) double knockout mice and investigated age-dependent liver disease progression in these animals. Deletion of CcnE1 in NEMO(∆hepa) mice decreased basal liver damage and reduced spontaneous liver inflammation in young mice. In contrast, loss of CcnE2 did not affect liver injury in NEMO(∆hepa) livers pointing to a unique, non-redundant function of CcnE1 in chronic hepatitis. Accordingly, basal compensatory hepatocyte proliferation in NEMO(∆hepa) mice was reduced by concomitant ablation of CcnE1, but not after loss of CcnE2. In aged NEMO(∆hepa) mice, loss of CcnE1 resulted in significant reduction of liver tumor-igenesis, while deletion of CcnE2 had no effect on HCC formation. CONCLUSION: CcnE1, but not its orthologue CcnE2 substantially contributes to hepatic inflammatory response, liver disease progression and hepatocarcinogenesis in NEMO(∆hepa) mice.

International journal of molecular sciences 20(2), 308 (2019). doi:10.3390/ijms20020308, Published by Molecular Diversity Preservation International, Basel

Background & Aims: During liver inflammation, triggering fibrogenesis and carcinogenesis immune cells play a pivotal role. In the present study we investigated the role of CCL5 in human and in murine models of chronic liver inflammation leading to hepatocellular carcinoma (HCC) development.Methods: CCL5 expression and its receptors were studied in well-defined patients with chronic liver disease (CLD) and in two murine inflammation based HCC models. The role of CCL5 in inflammation, fibrosis, tumor initiation and progression was analyzed in different cell populations of NEMO Delta hepa/CCL5(-/-) animals and after bone marrow transplantation (BMT). For therapeutic intervention Evasin-4 was injected for 24 h or 8 weeks.Results: In CLD patients, CCL5 and its receptor CCR5 are overexpressed - an observation confirmed in the Mdr2(-/-) and NEMO Delta hepa model. CCL5 deletion in NEMODhepa mice diminished hepatocyte apoptosis, compensatory proliferation and fibrogenesis due to reduced immune cell infiltration. Especially, CD45(+)/ Ly6G(+) granulocytes, CD45(+)/CD11b(+)/Gr1.1(+)/F4/80(+) proinflammatory monocytes, CD4(+) and CD8(+) T cells were decreased. One year old NEMO Delta hepa/CCL5 (/) mice displayed smaller and less malignant tumors, characterized by reduced proliferative capacity and less pronounced angiogenesis. We identified hematopoietic cells as the main source of CCL5, while CCL5 deficiency did not sensitise NEMO Delta hepa hepatocytes towards TNF alpha induced apoptosis. Finally, therapeutic intervention with Evasin-4 over a period of 8 weeks ameliorated liver disease progression.Conclusion: We identified an important role of CCL5 in human and functionally in mice with disease progression, especially HCC development. A novel approach to inhibit CCL5 in vivo thus appears encouraging for patients with CLD.Lay summary: Our present study identifies the essential role of the chemoattractive cytokine CCL5 for liver disease progression and especially hepatocellular carcinoma development in men and mice. Finally, the inhibition of CCL5 appears to be encouraging for therapy of human chronic liver disease. (C) 2016 European Association for the Study of the Liver. Published by Elsevier B. V. All rights reserved.

Full-length IL-33 is a member of the IL-1 family of cytokines, which can act in an autocrine or paracrine manner by binding to the IL-33R on several different target cell types. In addition, IL-33 can act in an intracrine fashion by translocating to the nucleus, where it binds to the chromatin and modulates gene expression. In this article, we report that full-length IL-33, but not mature IL-33, interacts with the transcription factor NF-κB. This interaction occurs between the N-terminal part of IL-33 from aa 66–109 and the N-terminal Rel homology domain of NF-κB p65. Coimmunoprecipitation experiments in cells overexpressing IL-33 or endogenously expressing IL-33 revealed rhIL-1β–stimulated association between IL-33 and p65, whereas binding to the p50 subunit was constitutive. The biological consequence of IL-33/NF-κB complex formation was reduction in NF-κB p65 binding to its cognate DNA and impairment of p65-triggered transactivation. Overexpression of IL-33 resulted in a reduction and delay in the rhIL-1β–stimulated expression of endogenous NF-κB target genes such as IκBα, TNF-α, and C-REL. We suggest that nuclear IL-33 sequesters nuclear NF-κB and reduces NF-κB–triggered gene expression to dampen proinflammatory signaling.

To secure the functionality of activated macrophages in the innate immune response, efficient life span control is required. Recognition of bacterial lipopolysaccharides (LPS) by toll-like receptor 4 (TLR4) induces downstream signaling pathways, which merge to induce the expression of cytokine genes and anti-apoptotic genes. MicroRNAs (miRNAs) have emerged as important inflammatory response modulators, but information about their functional impact on apoptosis is scarce. To identify miRNAs differentially expressed in response to LPS, cDNA libraries from untreated and LPS-activated murine macrophages were analyzed by deep sequencing and regulated miRNA expression was verified by Northern blotting and qPCR. Employing TargetScan(TM) we identified CASPASE-3 (CASP-3) mRNA that encodes a key player in apoptosis as potential target of LPS-induced miR-155. LPS-dependent primary macrophage activation revealed TLR4-mediated enhancement of miR-155 expression and CASP-3 mRNA reduction. Endogenous CASP-3 and cleaved CASP-3 protein declined in LPS-activated macrophages. Accumulation of miR-155 and CASP-3 mRNA in miRNA-induced silencing complexes (miRISC) was demonstrated by ARGONAUTE 2 (AGO2) immunoprecipitation. Importantly, specific antagomir transfection effectively reduced mature miR-155 and resulted in significantly elevated CASP-3 mRNA levels in activated macrophages. In vitro translation assays demonstrated that the target site in the CASP-3 mRNA 3'UTR mediates miR-155-dependent Luciferase reporter mRNA destabilization. Strikingly, Annexin V staining of macrophages transfected with antagomir-155 and stimulated with LPS prior to staurosporine (SSP) treatment implied that LPS-induced miR-155 prevents apoptosis through CASP-3 mRNA down-regulation. In conclusion, we report that miR-155-mediated CASP-3 mRNA destabilization in LPS-activated RAW 264.7 macrophages suppresses apoptosis, as a prerequisite to maintain their crucial function in inflammation.