transforming-growth-factor-beta and Liver-Failure--Acute

Acute liver failure is a serious consequence of acetaminophen (APAP)-induced hepatotoxic liver injury with high rates of morbidity and mortality. Transforming growth factor beta 1 (TGFβ1) is elevated during liver injury and influences hepatocyte senescence during APAP-induced hepatotoxicity. This study investigated TGFβ1 signaling in the context of inflammation, necrotic cell death, and oxidative stress during APAP-induced liver injury. Male C57Bl/6 mice were injected with 600 mg/kg APAP to generate liver injury in the presence or absence of the TGFβ receptor 1 inhibitor, GW788388, 1 h prior to APAP administration. Acetaminophen-induced liver injury was characterized using histological and biochemical measures. Transforming growth factor beta 1 expression and signal transduction were assessed using immunohistochemistry, Western blotting and ELISA assays. Hepatic necrosis, liver injury, cell proliferation, hepatic inflammation, and oxidative stress were assessed in all mice. Acetaminophen administration significantly induced necrosis and elevated serum transaminases compared with control mice. Transforming growth factor beta 1 staining was observed in and around areas of necrosis with phosphorylation of SMAD3 observed in hepatocytes neighboring necrotic areas in APAP-treated mice. Pretreatment with GW788388 prior to APAP administration in mice reduced hepatocyte cell death and stimulated regeneration. Phosphorylation of SMAD3 was reduced in APAP mice pretreated with GW788388 and this correlated with reduced hepatic cytokine production and oxidative stress. These results support that TGFβ1 signaling plays a significant role in APAP-induced liver injury by influencing necrotic cell death, inflammation, oxidative stress, and hepatocyte regeneration. In conclusion, targeting TGFβ1 or downstream signaling may be a possible therapeutic target for the management of APAP-induced liver injury.

Topics: Acetaminophen; Animals; Antioxidants; Apoptosis; Benzamides; Cell Death; Chemical and Drug Induced Liver Injury; Glutathione; Hepatocytes; Inflammation; JNK Mitogen-Activated Protein Kinases; Liver; Liver Failure, Acute; Male; Mice; Mice, Inbred C57BL; Necrosis; Oxidative Stress; Phosphorylation; Protective Agents; Pyrazoles; Regeneration; Signal Transduction; Transforming Growth Factor beta

Fulminant hepatic failure (FHF) is a clinical syndrome characterized by sudden and severe impairment of liver function. Mesenchymal stem cells (MSCs) have been proposed as a promising therapeutic approach for FHF. In this study we used Propionibacterium acnes (P. acnes)-primed, lipopolysaccharide (LPS)-induced liver injury in mice as an animal model of human FHF. We demonstrated that administration of MSCs significantly ameliorated liver injury and improved the survival rates of mice subjected to P. acnes plus LPS-induced FHF. Allogeneic MSCs showed similar treatment efficacy as autologous MSCs did in FHF. Treatment efficacy of MSCs could be attributed to decreased infiltration and activation of CD4(+) T cells in the liver, inhibition of T helper 1 cells, and induction of regulatory T cells (Tregs). Moreover, decreased DNA copies of P. acnes were detected in the liver of MSC-treated mice. Intriguingly, a distinct liver population of CD11c(+) MHCII(hi) CD80(lo) CD86(lo) regulatory dendritic cells (DCs) was induced by MSCs. Moreover, these DCs induced Treg differentiation through transforming growth factor-β production. Further mechanistic studies demonstrated that MSC-derived prostaglandin E2 and one of its receptors, EP4, played essential roles in the differentiation of CD11c(+) B220(-) DC precursors into regulatory DCs in a phosphoinositide 3-kinase-dependent manner.. MSCs induce regulatory DCs from CD11c(+) B220(-) DC precursors. This study elucidates an immunoregulatory mechanism of MSCs and lays a foundation for application of MSCs in FHF therapy.

Topics: Animals; Cell- and Tissue-Based Therapy; Dendritic Cells; Disease Models, Animal; Gram-Positive Bacterial Infections; Lipopolysaccharides; Liver; Liver Failure, Acute; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Propionibacterium acnes; Receptors, Prostaglandin E, EP4 Subtype; Signal Transduction; T-Lymphocytes, Regulatory; Th1 Cells; Transforming Growth Factor beta

T helper cells17 (Th17) have accurate but inconclusive roles in the pathogenesis of acute-on-chronic hepatitis B liver failure (ACHBLF). Retinoic acid-related orphan receptor γ t(RORγt) and RORα are two lineage-specific nuclear receptors directly mediating Th17 differentiation. This study was aimed to evaluate the gene expression of RORα and RORγt and their potential role in ACHBLF. Forty patients with liver failure, 30 with chronic hepatitis B (CHB) and 20 healthy controls were studied. The mRNA levels of RORα and RORγt in peripheral mononuclear cells were determined by quantitative real-time polymerase chain reaction. The frequency of peripheral Th17 cells was determined using flow cytometry. The serum levels of interleukin-6(IL-6), transforming growth factor -β (TGF-β), interleukin-17(IL-17), interleukin-23(IL-23) and interferon-γ (IFN-γ) were measured by enzyme-linked immunosorbent assay. The frequency of peripheral Th17 cells in patients with liver failure was significantly increased compared to patients with CHB and controls. The peripheral mRNA levels of RORα and RORγt in hepatitis B-associated acute-on-chronic liver failure were significantly higher than in patients with CHB and controls as were the serum levels of IL-6 and TGF-β. The serum level of IFN-γ in patients with acute-on-chronic liver failure from HBV was significantly higher than patients with CHB but lower than controls. In patients with acute-on-chronic liver failure associated with HBV, RORγt, IL-6 and IL-23 were positively correlated with the frequency of Th17 cells, while RORα, TGF-β and IFN-γ had no correlation with the latter. The mRNA level of RORγt was positively correlated with model of end-stage liver disease (MELD) score, but there was no correlation of RORα and MELD score. RORγt plays an important role in the pathogenesis of acute-on-chronic HBV-associated liver failure and might be considered to be a candidate factor consistent with the severity of disease.

Topics: Adult; Female; Hepatitis B, Chronic; Humans; Interferon-gamma; Interleukin-17; Interleukin-23; Interleukin-6; Liver Failure, Acute; Lymphocyte Count; Male; Nuclear Receptor Subfamily 1, Group F, Member 1; Nuclear Receptor Subfamily 1, Group F, Member 3; RNA, Messenger; Severity of Illness Index; Th17 Cells; Transforming Growth Factor beta

Liver regeneration may be impaired in acute liver failure due to either inhibition of the proliferative response or ongoing liver cell death. Activin A, a member of the TGFbeta superfamily, inhibits hepatocyte DNA synthesis and induces apoptosis.. Levels of activin A and its binding protein follistatin in the serum of 23 patients with acute liver failure were determined by enzyme-linked immunosorbent assay.. Serum activin A was significantly increased in acute liver failure patients (median 2.15 ng/ml, range 0.28-6.87 ng/ml) compared to normal controls (median 0.25 ng/ml, range 0.19-0.53 ng/ml; = 10; 0.001). However, this was not linked to the final disease outcome. Higher levels of activin A were found in the serum of patients with acute liver failure due to paracetamol overdose (median 2.87 ng/ml, range 0.72-6.87 ng/ml; = 17) than in patients with acute liver failure due to non-A to E hepatitis (median 1.10 ng/ml, range 0.28-2.70 ng/ml; = 6; 0.05). Serum follistatin was also increased in acute liver failure patients (median 2.84 ng/ml, range 0.57-13.24 ng/ml) compared to normal controls (median 0.68 ng/ml, range 0.32-3.70 ng/ml; 0.01).. Serum activin A is increased in acute liver failure and could be a factor in the inhibition of liver regeneration.

Topics: Acetaminophen; Activins; Adolescent; Adult; Analgesics, Non-Narcotic; Biomarkers; Enzyme-Linked Immunosorbent Assay; Female; Follistatin; Hepatitis; Humans; Inhibin-beta Subunits; Liver Failure, Acute; Male; Middle Aged; Thymidine; Transforming Growth Factor beta; Tumor Cells, Cultured

It has been observed that liver regeneration in acute hepatic failure (AHF) is suppressed [Eguchi et al. Hepatology 1996;24(6):1452-9]. The molecular mechanism regulating this inhibition is not known. We previously reported that in AHF rats, hepatocyte proliferation was significantly impaired with elevation in serum IL-6, TGF-beta1, and HGF [Kamohara et al. Biochem Biophys Res Commun 2000;273(1):129-35]. Following either 70% partial hepatectomy (PH) or liver injury, quiescent mature hepatocytes are "primed" to re-enter the cell cycle. The process of "priming" appears to be triggered by extracellular cytokines (IL-6 and TNF-alpha) and is characterized by expression of immediate early genes. Under the stimulation of growth factors such as HGF, "primed" hepatocytes exit the G1 phase of the cell cycle. G1-associated cyclins and their inhibitors play a pivotal role in G1/S cell cycle transition. Here, we demonstrate that immediate early gene (i.e. c-myc, c-fos) expression and AP-1 activity are preserved in AHF rat livers despite absence of hepatocyte proliferation. In contrast, p21 mRNA and protein are both over-expressed in AHF livers compared to livers from rats undergoing PH; this elevation leads to inhibition in Cdk2 activity, resulting in G1 cell cycle arrest and inhibition of regeneration.

Topics: Animals; Blotting, Northern; Blotting, Western; CDC2-CDC28 Kinases; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinases; Gene Expression; Genes, fos; Genes, Immediate-Early; Genes, myc; Hepatectomy; Interleukin-6; Liver Failure, Acute; Liver Regeneration; Male; Protein Serine-Threonine Kinases; Rats; Rats, Sprague-Dawley; rho GTP-Binding Proteins; Transcription Factor AP-1; Transforming Growth Factor beta; Transforming Growth Factor beta1

Earlier we described a model of fulminant hepatic failure (FHF) in the rat where partial hepatectomy is combined with induction of right liver lobe necrosis. In FHF rats, lack of hepatocyte proliferation was associated with delayed expression of HGF and HGF receptor c-met. Since the c-met promoter region has Sp1 binding sites, we decided to examine whether in FHF rats down-regulation of c-met is associated with decreased Sp1 function and whether changes in blood HGF, IL-6, and TGFbeta1 levels might be responsible for these effects.. Induction of FHF, partial (2/3) hepatectomy (PH), and sham hepatectomy (SH) was performed in adult Sprague-Dawley rats. The levels of c-met mRNA and Sp1 DNA binding activity were studied in rat liver remnants at different time points after surgery. Blood levels of HGF, IL-6, and TGFbeta1 were also measured in these rats. Additionally, the effects of treatment with TGF-beta1, IL-6, or a combination of both on c-met expression and Sp1 DNA binding were studied in HGF-induced rat hepatocyte cultures.. Compared to SH rats, in PH rat livers c-met was up-regulated after 6 h and Sp1 DNA binding was at or only slightly lower than levels at all time points studied. In FHF rat livers, c-met expression was markedly reduced after 2 and 6 h, moderate after 12 h, and undetectable after 24 h. At the same time, Sp1 DNA binding was detected at 2 h postinduction only. In FHF rats, blood levels of all three cytokines showed early and sustained elevation. In vitro, IL-6 had no effect on c-met expression, whereas TGFbeta1 up-regulated c-met. When used alone, none of the cytokines affected Sp1 DNA binding activity. In contrast, a combination of IL-6 and TGFbeta1 down-regulated c-met expression as well as Sp1 DNA binding activity. These effects were dependent on the IL-6 concentration used. This study suggests that following massive loss of hepatocyte mass in rats, early increase in blood IL-6 and TGFbeta1 levels may weaken the expression of HGF receptor c-met in surviving hepatocytes through suppression of Sp1 DNA binding.

Topics: Animals; Cell Division; Cells, Cultured; Gene Expression Regulation; Hepatocyte Growth Factor; Hepatocytes; Interleukin-6; Liver Failure, Acute; Liver Regeneration; Male; Proto-Oncogene Proteins c-met; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sp1 Transcription Factor; Transforming Growth Factor beta; Transforming Growth Factor beta1

The aim of this study was to investigate the effects of treatment with the extracorporeal liver assist device (ELAD) in patients with acute liver failure (ALF) on plasma hepatocyte growth factor (HGF), the most potent growth factor, and transforming growth factor-beta 1 (TGF-beta 1), an inhibitory factor for liver regeneration. Initial plasma HGF, measured by ELISA, was significantly increased in the ALF patients (7.86 +/- SEM 1.76 ng/ml) compared with normal subjects (0.10 +/- 0.02 ng/ml, p < 0.001). After 6 hours of ELAD haemoperfusion, plasma HGF increased further (30.5 +/- 6.19 ng/ml, p < 0.001), with a subsequent decrease towards the initial value by 48 hours. Initial plasma levels of TGF-beta 1 determined by ELISA were significantly increased in the ALF patients (43.4 +/- 5.9 ng/ml) compared with normal subjects (25.1 +/- 2.3 ng/ml, p < 0.01), but there was no change in plasma TGF-beta 1 during the study period in either the ELAD or control ALF group. As HGF is a heparin-binding growth factor and similar changes in HGF were observed during CVVHD, one possible explanation is that heparin administered as anticoagulant for extracorporeal circulation is involved in the effects observed on HGF.

Topics: Adolescent; Adult; Aged; Artificial Organs; Enzyme-Linked Immunosorbent Assay; Extracorporeal Circulation; Female; Hemoperfusion; Heparin; Hepatocyte Growth Factor; Humans; Liver Failure, Acute; Liver Regeneration; Male; Middle Aged; Molecular Weight; Transforming Growth Factor beta