Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The IL-33/ST2 axis is known to be involved in liver pathologies. Although, the IL-33 levels increased in sera of viral hepatitis patients in human, the cellular sources of IL-33 in viral hepatitis remained obscure. Therefore, we aimed to investigate the expression of IL-33 in murine fulminant hepatitis induced by a Toll like receptor (TLR3) viral mimetic, poly(I:C) or by pathogenic mouse hepatitis virus (L2-MHV3). The administration of poly(I:C) plus D-galactosamine (D-GalN) in mice led to acute liver injury associated with the induction of IL-33 expression in liver sinusoidal endothelial cells (LSEC) and vascular endothelial cells (VEC), while the administration of poly(I:C) alone led to hepatocyte specific IL-33 expression in addition to vascular IL-33 expression. The hepatocyte-specific IL-33 expression was down-regulated in NK-depleted poly(I:C) treated mice suggesting a partial regulation of IL-33 by NK cells. The CD1d KO (NKT deficient) mice showed hepatoprotection against poly(I:C)-induced hepatitis in association with increased number of IL-33 expressing hepatocytes in CD1d KO mice than WT controls. These results suggest that hepatocyte-specific IL-33 expression in poly(I:C) induced liver injury was partially dependent of NK cells and with limited role of NKT cells. In parallel, the L2-MHV3 infection in mice induced fulminant hepatitis associated with up-regulated IL-33 expression as well as pro-inflammatory cytokine microenvironment in liver. The LSEC and VEC expressed inducible expression of IL-33 following L2-MHV3 infection but the hepatocyte-specific IL-33 expression was only evident between 24 to 32h of post infection. In conclusion, the alarmin cytokine IL-33 was over-expressed during fulminant hepatitis in mice with LSEC, VEC and hepatocytes as potential sources of IL-33.
ISSN: 1932-6203

hal-00874120
https://hal.archives-ouvertes.fr/hal-00874120
https://hal.archives-ouvertes.fr/hal-00874120/document
https://hal.archives-ouvertes.fr/hal-00874120/file/Pathogenic_Mouse_Hepatitis-accepted.pdf
DOI : 10.1371/journal.pone.0074278

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Development of hepatocellular carcinoma (HCC) is a complex and progressive disease that involves cycles of liver cell death, inflammation, and tissue regeneration/remodelling. Chemokines and chemokine receptors play numerous and integral roles in the disease progression of HCC. Here we investigated the novel chemokine receptor CXCR7/RDC1 in HCC progression, its two known ligands CXCL12 and CXCL11, as well as the other CXCL12 receptor, CXCR4. Our results show that in a cohort of 408 human HCCs, CXCR7 and CXCL11 were significantly higher in tumours compared to normal liver controls (5- and 10-fold, respectively). Immunohistochemical (IHC) staining on human HCC sections confirmed that both CXCL11 and CXCR7 were much higher in cancer tissues. Furthermore, IHC staining revealed that CXCR7 protein was only expressed in endothelial cells whereas CXCL11 exhibited a much broader tissue expression. At the cellular level we observed that in vitro, human microvascular endothelial cells (HMEC-1) up-regulated CXCR7 under hypoxic and acidic pH conditions, which are well known characteristics of the HCC tumour micro-environment. As for its ligand, we observed that IFNγ robustly induced CXCL11 in hepatic stellate cells, hepatocytes, and HMEC-1s. In addition, in the mouse Diethylnitrosamine model of hepatocarcinogenesis we observed a very strong induction of CXCR7 and CXCL11 transcripts, confirming that CXCR7/CXCL11 up-regulation is conserved between human and mice liver cancer. Altogether, our results strongly support the hypothesis that the CXCL11/CXCR7 pathway is involved HCC progression.
ISSN: 0959-8049

hal-00682463
https://hal.archives-ouvertes.fr/hal-00682463
DOI : 10.1016/j.ejca.2011.06.044
PUBMED : 21778049

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Interleukin-33 (IL-33), a cytokine belonging to the IL-1 family, is crucially involved in inflammatory pathologies including liver injury and linked to various modes of cell death. However, a link between IL-33 and necroptosis or programmed necrosis in liver pathology remains elusive. We aimed to investigate the regulation of IL-33 during necroptosis-associated liver injury. The possible regulation of IL-33 during liver injury by receptor-interacting protein kinase 1 (RIPK1) and poly(ADP-ribose) polymerase 1 (PARP-1) was investigated in mice in vivo and in hepatic stellate cells in vitro. The liver immunohistopathology, flow cytometry, serum transaminase measurement, ELISA, and qPCR-based cytokine measurement were carried out. By using a chemical approach, we showed that pretreatment of mice with Necrostatin-1 (Nec-1) (inhibitor of RIPK1) and/or PJ34 (inhibitor of PARP-1) significantly protected mice against concanavalin A (ConA) liver injury (aspartate amino-transferase (AST)/alanine amino-transferase (ALT)) associated with down-regulated hepatocyte-specific IL-33 expression. In contrast, the expression level of most systemic cytokines (except for IL-6) or activation of liver immune cells was not altered by chemical inhibitors rather an increased infiltration of neutrophils in the liver. During polyinosine-polycytidylic acid (Poly(I:C))-induced acute hepatitis, liver injury and hepatocyte-specific IL-33 expression was also inhibited by PJ34 without any protective effect of PJ34 in CCl4-induced liver injury. Moreover, PJ34 down-regulated the protein expression of IL-33 in activated hepatic stellate cells by cocktail of cytokines or staurosporine in vitro. In conclusion, we evidenced that the Nec-1/PJ34 is a potent inhibitor of liver injury and Nec-1/PJ34 down-regulated hepatocyte-specific IL-33 expression in the liver in vivo or in hepatic stellate cells in vitro, suggesting IL-33 as a possible readout of necroptosis-involved liver pathologies. Necroptosis inhibitors can protect mice against liver injury induced by ConA or Poly(I:C). IL-33 expression in liver injury in vivo is inhibited by PJ34. IL-33 expression in hepatic stellate cells in vitro is inhibited by PJ34. Hepatocyte-specific IL-33 expression is down-regulated by Nec-1/PJ34 during hepatitis. IL-33 is a new marker of necroptosis-associated liver injuries.
ISSN: 0946-2716

hal-01134319
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134319
DOI : 10.1007/s00109-015-1270-6
PUBMED : 25747661

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
UNLABELLED: Interleukin (IL)-33, a member of the IL-1 cytokine family, positively correlates with acute hepatitis and chronic liver failure in mice and humans. IL-33 is expressed in hepatocytes and is regulated by natural killer T (NKT) cells during concanavalin A (ConA)-induced acute liver injury. Here, we investigated the molecular mechanisms underlying the expression of IL-33 during acute hepatitis. The expression of IL-33 and its regulation by death receptor pathways was investigated after the induction of ConA-acute hepatitis in wildtype (WT), perforin(-/-) , tumor necrosis factor related apoptosis inducing ligand (TRAIL)(-/-) , and NKT cell-deficient (CD1d(-/-) ) mice. In addition, we used a model of acute liver injury by administering Jo2/Fas-antibody or D-galactosamine-tumor necrosis factor alpha (TNFα) in WT mice. Finally, the effect of TRAIL on IL-33 expression was assessed in primary cultured murine hepatocytes. We show that IL-33 expression in hepatocytes is partially controlled by perforin during acute liver injury, but not by TNFα or Fas ligand (FasL). Interestingly, the expression of IL-33 in hepatocytes is blocked during ConA-acute hepatitis in TRAIL-deficient mice compared to WT mice. In contrast, administration of recombinant murine TRAIL associated with ConA-priming in CD1d-deficient mice or in vitro stimulation of murine hepatocytes by TRAIL but not by TNFα or Jo2 induced IL-33 expression in hepatocytes. The IL-33-deficient mice exhibited more severe ConA liver injury than WT controls, suggesting a protective effect of IL-33 in ConA-hepatitis. CONCLUSION: The expression of IL-33 during acute hepatitis is dependent on TRAIL, but not on FasL or TNFα.
ISSN: 0270-9139

hal-00874194
https://hal.archives-ouvertes.fr/hal-00874194
PUBMED : 22961755
DOI : 10.1002/hep.25893

Éditeur(s) : HAL CCSD American Physiological Society
Résumé : International audience
Interleukin (IL)-33 is crucially involved in liver pathology and drives hepatoprotective functions. However, the regulation of IL-33 by cytokines of the IL-6 family, including oncostatin M (OSM) and IL-6, is not well studied. The aim of the present study was to determine whether OSM mediates regulation of IL-33 expression in liver cells. Intramuscular administration in mice of an adenovirus encoding OSM (AdOSM) leads to increase in expression of OSM in muscles, liver, and serum of AdOSM-infected mice compared with control mice. The increase of circulating OSM markedly regulated mRNA of genes associated with blood vessel biology, chemotaxis, cellular death, induction of cell adhesion molecules, and the alarmin cytokine IL-33 in liver. Steady-state IL-33 mRNA was upregulated by OSM at an early phase (8 h) following AdOSM infection. At the protein level, the expression of IL-33 was significantly induced in liver endothelial cells [liver sinusoidal endothelial cells (LSEC) and vascular endothelial cells] with a peak at 8 days post-AdOSM infection in mice. In addition, we found OSM-stimulated human microvascular endothelial HMEC-1 cells and human LSEC/TRP3 cells showed a significant increase in expression of IL-33 mRNA in a dose-dependent manner in cell culture. The OSM-mediated overexpression of IL-33 was associated with the activation/enrichment of CD4(+)ST2(+) cells in liver of AdOSM-infected mice compared with adenovirus encoding green fluorescent protein-treated control mice. In summary, these data suggest that the cytokine OSM regulates the IL-33 expression in liver endothelial cells in vivo and in HMEC-1/TRP3 cells in vitro and may specifically expand the target CD4(+)ST2(+) cells in liver
ISSN: 0193-1857

hal-01220632
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01220632
DOI : 10.1152/ajpgi.00398.2014
PUBMED : 26251474

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND AND AIMS: Infection by hepatitis C virus is a worldwide health problem. An inadequate Th2 cytokine response promotes the fibrosis-cirrhosis fate. Immune-modulating molecules favoring a Th2 profile, such as HLA-G molecules of the HLA class Ib family, may play a role in chronic hepatitis. HLA-G contributes to the escape of tumors, and their involvement in viral infections has been increasingly described. The aim of this work was to study the expression of HLA-G in the liver, its cellular source and its regulation in cases of chronic C hepatitis. METHODS: HLA-G cells in blocks of liver derived from patients infected with HCV were labeled by immunohistochemistry and enumerated. Double immunofluorescence allowed the identification of the cellular source. HLA-G secretion by a human mast cell line was quantified by ELISA after various stimulations. After treatment with IFN-α real-time PCR was performed to determine the kinetics of cytokine expression profiles, followed by heat map clustering analysis. RESULTS: The number of HLA-G + cells was significantly associated with the area of fibrosis. For the first time, we identify the HLA-G+ cells as being mast cells. HLA-G secretion was significantly induced in human mast cells stimulated by IL-10 or interferons of class I. The transcriptome of the secretome of this cell line stimulated by IFN-α revealed that i) the HLA-G gene is upregulated late, ii) T lymphocytes and NK cells are recruited. CONCLUSIONS: These findings suggest an autocrine loop in the genesis of HCV liver fibrosis, based on mast cells expressing HLA-G.
ISSN: 0168-8278

hal-00874106
https://hal.archives-ouvertes.fr/hal-00874106
https://hal.archives-ouvertes.fr/hal-00874106/document
https://hal.archives-ouvertes.fr/hal-00874106/file/Amiot-Expression-HLA-G-revised.pdf
DOI : 10.1016/j.jhep.2013.09.006