1,720,978 research outputs found
Cytokine-induced neutrophil chemoattractant-1 is released by the noninjured liver in a rat acute-phase model
No full textThe source of serum cytokine-induced neutrophil chemoattractant ( CINC-1) and consequences of its presence in the tissue of synthesis have not been clearly elucidated under acute-phase situation. To pursue this question, turpentine oil ( TO) was intramuscularly injected into rats, and RNA and local protein levels of acute-phase cytokines and of CINC-1 were studied in the TO injected gluteal muscle, as well as in noninjured muscle, in the liver, kidney, lung and spleen. The serum levels of acute-phase mediators and of CINC-1 were measured together with total leukocyte subpopulations. Recruitment of inflammatory cells in muscle and in the other organs was investigated by quantitative immunohistochemical methods. The effect of acute-phase mediators, including interferon gamma ( IFN-gamma) on the synthesis of CINC-1 in cultured hepatocytes was also investigated at the RNA and protein level. We found that the sera of the TO-treated rats contained elevated levels of IL-6, IL-1 beta and CINC-1. Increased serum levels of IFN-gamma were also observed not only in the injured muscle but also and to a higher extent in the liver. However, while neutrophils and mononuclear phagocytes were found in the injured muscle, no inflammatory cells were detected at the non-'inflamed' site, namely, the liver or in the other organs. In vitro, treatment of cultured hepatocytes with IL-1 beta led to elevated CINC-1 gene expression. This was true to a lesser extent upon IL-6 and tumor necrosis factor ( TNF-alpha) exposure. Interestingly, IFN-gamma did not effect CINC-1 gene expression. These results indicate that CINC-1 behaves as an acute-phase protein and its expression is inducible in hepatocytes. However, CINC-1-production in the liver does not lead to recruitment of inflammatory cells into the organ
Modulation of fibronectin gene expression in inflammatory mononuclear phagocytes of rat liver after acute liver injury
No full textBackground/Aims: In acute liver injury, fibronectin (FN) is deposited at the site of hepatocellular necrosis. We have previously shown that liver inflammatory mononuclear phagocytes (MNP), in contrast to quiescent hepatic macrophages, synthesize abundant amounts of FN. We now analyzed effects of agents known to influence macrophage functions to better understand liver damage and repair. Methods: Acute rat liver injury was induced by CCl4. Liver cellular FN (cFN) expression was analyzed by in situ-hybridization. Liver MNP were isolated and characterized immunocytochemically. Protein synthesis was studied by biosynthetic labeling, immunoprecipitation, and SDS-PAGE. RNA was analyzed by Northern Blotting. Results: cFN gene expression was localized by in situ-hybridization and immunohistochemistry within the pericentral inflammatory infiltrate. Treatment of inflammatory MNP with dexamethasone, or interferon-gamma, or lipopolysaccharide induced a dose-dependent decrease in cFN gene expression, whereas transforming growth factor-P increased cFN gene expression. Conclusions: 1. Inflammatory MNP express cFN. 2. Downregulation of cFN expression by dexamethasone in inflammatory MNP may explain delayed wound healing after corticosteroid therapy. Interferon-gamma and lipopolysaccharide could also delay the repair process in the liver. Transforming growth factor-beta may promote liver wound healing after acute liver injury by increasing local cFN synthesis in inflammatory mononuclear phagocytes of the inflammatory infiltrate. (C) 2004 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved
Research article
No full textBackground and aim: The mechanisms of transmigration of inflammatory cells through the sinusoids are still poorly understood. This study aims to identify in vitro conditions (cytokine treatment) which may allow a better understanding of the changes in PECAM (platelet endothelial cell adhesion molecule)-1-gene-expression observed in vivo. Methods and results: In this study we show by immunohistochemistry, that there is an accumulation of ICAM-1 (intercellular cell adhesion molecule-1) and ED1 positive cells in necrotic areas of livers of CCl4-treated rats, whereas there are few PECAM-1 positive cells observable. After the administration of CCl4, we could detect an early rise of levels of IFN-? followed by an enhanced TGF-? protein level. As shown by Northern blot analysis and surface protein expression analysed by flow cytometry, IFN-?-treatment decreased PECAM-1-gene-expression in isolated SECs (sinusoidal endothelial cells) and mononuclear phagocytes (MNPs) in parallel with an increase in ICAM-1-gene-expression in a dose and time dependent manner. In contrast, TGF-?-treatment increased PECAM-1-expression. Additional administration of IFN-? to CCl4-treated rats and observations in IFN-?-/- mice confirmed the effect of IFN-? on PECAM-1 and ICAM-1-expression observed in vitro and increased the number of ED1-expressing cells 12 h after administration of the toxin.Conclusion: The early decrease of PECAM-1-expression and the parallel increase of ICAM-1-expression following CCl4-treatment is induced by elevated levels of IFN-? in livers and may facilitate adhesion and transmigration of inflammatory cells. The up-regulation of PECAM-1-expression in SECs and MNPs after TGF-?-treatment suggests the involvement of PECAM-1 during the recovery after liver damage
Expression of AFP and Rev-Erb A/Rev-Erb B and N-CoR in fetal rat liver, liver injury and liver regeneration
No full textBackground: Alpha-fetoprotein (AFP) expression can resume in the adult liver under pathophysiological conditions. Orphan nuclear receptors were supposed to regulate AFP gene expression, in vitro. We were interested to study the expression of AFP and orphan nuclear receptors, in vivo. Results: The expression of AFP gene and orphan nuclear receptors in the liver was examined in different rat models: (a) fetal liver (b) liver regeneration [partial hepatectomy (PH) with and without 2-acetyl-aminofluren treatment (2-AAF)], (c) acute liver damage [treatment with CCl4] and (d) acute phase reaction treatment with turpentine oil]. After PH of 2-AAF treated rats, clusters of AFP positive cells occurred in the periportal region. In the Northern blot analysis, a positive hybridization signal for the full-length AFP-RNA was observed only in liver samples from 2-AAF treated rats after PH. In real-time PCR analysis, the full-length AFP-RNA was highly up regulated in the fetal liver (maximum at day 14: 21,500 fold); after PH of 2-AAF treated rats, the full-length AFPRNA was also up regulated up to 400 fold (day 7 after PH). The orphan nuclear receptors were down regulated at nearly each time points in all models, also at time point of up regulation of the AFP gene..
Hepcidin and hemojuvelin gene expression in rat liver damage: In vivo and in vitro studies
No full textIdentification of genes specific to "oval cells" in the rat 2-acteylaminofluorene/partial hepatectomy model
No full textIdentification of genes specific to rat 2-acetylaminofluorene/partial 'oval cells" in the hepatectomy model
No full textUnder certain conditions liver regeneration can be accomplished by hepatic progenitor cells ("oval cells"). So far, only few factors have been identified to be uniquely regulated by the "oval cell" compartment. Using macroarray analysis in a rat model of oval cell proliferation (treatment with 2-acetylaminofluorene and partial hepatectomy, AAF + PH), we identified 12 differentially expressed genes compared to appropriate control models (AAF treatment and sham operation or AAF treatment alone). Further analysis in models of normal liver regeneration (ordinary PH) and acute phase response (turpentine oil-treated rats) revealed that three out of 12 genes (thymidine kinase 1, Jun-D and ADP-ribosylation factor 4) were not affected by the hepatic acute phase reaction but similarly overexpressed in both "oval cell" -dependant and normal liver regeneration. We characterized Jun-D and ADP-ribosylation factors as novel factors upregulated in oval cells and in nonparenchymal liver cells of normally regenerating livers. However, two out of 12 differentially expressed genes were specifically expressed in oval cells: ras-related protein Rab-3b and Ear-2. On protein level, Rab-3b was increased in total liver homogenates and demonstrated only in clusters of oval cells. We postulate that Ear-2 and Rab-3b may represent novel regulatory factors specifically activated in "oval cells"
Identification of genes specific to "oval cells" in the rat 2-acteylaminofluorene/partial hepatectomy model
No full textUpregulation of heme oxygenase-1 gene by turpentine oil-induced localized inflammation: involvement of interleukin-6
No full textHeme oxygenase- 1 ( HO- 1) is the inducible isoform of an enzyme family responsible for heme degradation and was suggested to be involved in the acute phase response in the liver. However, the mechanisms of the HO- 1 regulation under inflammatory conditions are poorly understood. Therefore, the purpose of the current work was to study the expression of HO- 1 in the liver and other organs of rats with a localized inflammation after intramuscular injection of turpentine oil ( TO). Since interleukin- 6 ( IL- 6) is known to be a principal mediator of inflammation, the levels of this cytokine were also estimated in the animal model used. HO- 1 and IL- 6 expression was evaluated by Northern blot, in situ hybridization, Western blot, immunohistochemistry and enzyme- linked immunosorbent assay. In the liver and injured muscle, the HO- 1 mRNA levels were dramatically increased 4 - 6 h after TO administration. HO- 1 protein levels in the liver were elevated starting from 6 - 12 h after the treatment. In other internal organs such as the heart, kidney and large intestine, only a slight induction of HO- 1 mRNA was observed. IL- 6- specific transcripts appeared only in the injured muscle and were in accordance with serum levels of IL- 6. In turn, temporal expression of IL- 6 in the muscle and circulatory IL- 6 levels correlated well with HO- 1 expression in the liver and injured muscle. In the liver of control rats HO- 1 protein was detected in Kupffer cells, while in TO- injected rats also hepatocytes became strongly HO- 1 positive. Conversely, in the injured muscle, HO- 1 immunoreactivity was attributed only to macrophages. Our data demonstrate that during localized inflammation HO- 1 expression was rapidly and strongly induced in macrophages of injured muscle and in hepatocytes, and IL- 6 derived from injured muscle seems to be responsible for the HO- 1 induction in the liver
Regulation of rat heme oxygenase-1 expression by interleukin-6 via the Jak/STAT pathway in hepatocytes
No full textBackground/Aims: Heme oxygenase-1 (HO-1) can be induced by various stimuli, one of which is interleukin-6 (IL-6). Therefore, the aim of this study was to elucidate the molecular mechanisms responsible for IL-6-dependent HO-1 induction in the liver. Methods: The IL-6-dependent HO-1 regulation in rat primary hepatocytes and HepG2 hepatoma cells was studied by Northern and Western blot analyses, HO-1 promoter reporter gene assays and EMSA. Results: The HO-1 expression was transcriptionally induced by IL-6 in a time- and dose-dependent manner. Activation of signal transducers and activators of transcription (STAT) factors by the IL-6 receptor was crucial for HO-1 induction. By contrast, negative regulation of HO-1 expression appeared to be mediated through the SH2-domain-containing tyrosine phosphatase-2 (SHP2)/suppressors of cytokine signaling-3 (SOCS3) binding site within the gp130 IL-6 receptor subunit. Among the three putative STAT binding elements (SBE) in the HO-1 promoter, only the distal one was functional and when deleted, the remaining Luc induction was completely obliterated by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Conclusions: The HO-1 SBE3 mediates HO-1 gene induction by IL-6 mainly via activation of the Jak/STAT pathway. (c) 2006 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved
- …
