Role In Hepatocyte Apoptosis Research Articles

PSTPIP2 protects against alcoholic liver injury and invokes STAT3-mediated suppression of apoptosis

Alcoholic liver injury (ALI) stands as a prevalent affliction within the spectrum of complex liver diseases. Prolonged and excessive alcohol consumption can pave the way for liver fibrosis, cirrhosis, and even hepatocellular carcinoma. Recent findings have unveiled the protective role of proline serine-threonine phosphatase interacting protein 2 (PSTPIP2) in combating liver ailments. However, the role of PSTPIP2 in ALI remains mostly unknown. This study aimed to determine the expression profile of PSTPIP2 in ALI and to uncover the mechanism through which PSTPIP2 affects the survival and apoptosis of hepatocytes in ALI, using both ethyl alcohol (EtOH)-fed mice and an EtOH-induced AML-12 cell model. We observed a consistent decrease in PSTPIP2 expression both in vivo and in vitro. Functionally, we assessed the impact of PSTPIP2 overexpression on ALI by administering adeno-associated virus 9 (AAV9)-PSTPIP2 into mice. The results demonstrated that augmenting PSTPIP2 expression significantly shielded against liver parenchymal distortion and curbed caspase-dependent hepatocyte apoptosis in EtOH-induced ALI mice. Furthermore, enforcing PSTPIP2 expression reduced hepatocyte apoptosis in a stable PSTPIP2-overexpressing AML-12 cell line established through lentivirus-PSTPIP2 transfection in vitro. Mechanistically, this study also identified signal transducer and activator of transcription 3 (STAT3) as a direct signaling pathway regulated by PSTPIP2 in ALI. In conclusion, our findings provide compelling evidence that PSTPIP2 has a regulatory role in hepatocyte apoptosis via the STAT3 pathway in ALI, suggesting PSTPIP2 as a promising therapeutic target for ALI.

Comparison of nickel oxide nano and microparticles toxicity in rat liver: molecular, biochemical, and histopathological study.

The unique properties of nickel oxide nanoparticles distinguish it from classical nickel compounds, increasing its use in agriculture, industry, and many industrial areas. The aim of this study is to investigate the possible toxicity of nickel oxide and nickel oxide nanoparticles in the liver. For this purpose, Wistar rats were given nickel oxide and nickel oxide nanoparticles orally, intraperitoneally, and intravenously for 21days. Liver organ weight, biochemical and hematological parameters, oxidative stress (malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, and glutathione S transferase), acetylcholinesterase activities, inflammation levels, apoptotic markers, and histopathological changes were evaluated comparatively. When the data obtained were examined in general, it was observed that nickel oxide nanoparticles caused more hepatotoxicity in liver tissue than nickel oxide in terms of oxidative stress parameters, apoptotic markers, inflammation indicators, and other parameters examined. The results suggest that toxicity induced by both nickel oxide and nickel oxide nanoparticles plays an important role in hepatocyte apoptosis.

Therapeutic Effect of Crocin on the NASH Model by Targeting the Fas Receptor Signaling Pathway.

The role of hepatocyte apoptosis and inflammation has been implicated in the progression of nonalcoholic steatohepatitis (NASH). Overproduction of reactive oxygen species (ROS) appears to accelerate these pathways through the activation of Fas receptor signaling. Therefore, we explored the hepatoprotective effects of crocin as a strong free radical scavenger against oxidative damages leading to NASH development. Thirty-two male mice were randomly divided into control, NASH, NASH + crocin, and crocin groups. They received an intraperi- toneal injection of crocin twice a week, for 3 weeks. For NASH model induction, the animals were fed with a Western diet and exposed to cigarette smoke for 8 weeks. At the end of the experiment, liver histology, biochemical, and biomolecular analyses were done to evaluate the antioxidant, anti-inflammatory, and anti-apoptotic activities of crocin in the NASH model. Evaluation of the features of the NASH model revealed steatosis, inflammatory infiltrate, and ballooning degeneration. Metabolic dysfunction was associated with elevated serum levels of the lipid profile and decreased hepatic liver enzymes. The increased content of malondialdehyde (MDA) and reduced antioxidant activities confirmed hepatotoxicity induction. There was a significant increase in expression level of Fas, caspase 3, and NF-κB genes that was also associated with elevation in hepatic TNF-α content. Moreover, expression the of Fas receptor protein was significantly detected on the hepatocyte membrane. Treatment with crocin effectively improved NASH-related parameters, and the histopathological findings were also parallel with the resulting changes. Crocin can be introduced as a candidate hepatoprotective agent against NASH by virtue of its anti-inflammatory, antioxi- dant, and anti-apoptotic properties, possibly through regulation of the Fas death receptor pathway.

Blockade of the P2Y2 Receptor Attenuates Alcoholic Liver Inflammation by Targeting the EGFR-ERK1/2 Signaling Pathway.

PurposeIt is well known that inflammation plays a key role in complex pathological progressions of alcohol-associated liver disease (ALD). To date, effective therapy for ALD is lacking. P2Y2 receptor (P2Y2R), a G protein-coupled P2Y purinergic receptor, represents a novel pharmacological target in many inflammations.MethodsThe alcohol-associated liver injury and inflammation mouse model was established. The effect of P2Y2R on alcohol-induced liver injury and inflammation was evaluated using quantitative real-time PCR, Western blot and immunohistochemical assay. An alcohol-stimulated (100 mmol/L, for 24 h) AML-12 cell model was established. Different agonists, antagonists and P2Y2R siRNA were used to explore the possible mechanisms of P2Y2R.ResultsIn vivo, results showed that the hepatoprotective effect of P2Y2R blockade by significantly suppressed liver structural abnormalities and lipid infiltration, and decreased levels of ALT/AST and TNF-α/IL-1β in the high dosage group of suramin (20 mg/kg) compared to control diet (CD)-fed mice. At the same time, we found that alcohol feeding promoted the phosphorylation of EGFR and ERK1/2, both of which were effectively inhibited by suramin (20 mg/kg). In vitro, suramin or P2Y2R silencing effectively inhibited the phosphorylation of EGFR and ERK1/2, similar to the down-regulated effects of their corresponding inhibitors (EGFR inhibitor AG1478 and ERK1/2 inhibitor U0126) accompanied by reduced levels of TNF-α and IL-1β compared to alcohol-induced AML-12 cell. In addition, we found that silencing P2Y2R attenuated the apoptosis of hepatocyte.ConclusionOur findings suggest that P2Y2R regulates alcoholic liver inflammation by targeting the EGFR-ERK1/2 signaling pathway and plays an important role in hepatocyte apoptosis, which may provide new ideas for the development of methods to treat ALD.

Anti‑apoptotic effects of human placental hydrolysate against hepatocyte toxicity invivo and invitro.

Apoptosis and oxidative stress are essential for the pathogenesis of acute liver failure and fulminant hepatic failure. Human placental hydrolysate (hPH) has been reported to possess antioxidant and anti-inflammatory properties. In the present study, the protective effects of hPH against D-galactosamine (D-GalN)- and lipopolysaccharide (LPS)-induced hepatocyte apoptosis were investigated in vivo. In addition, the molecular mechanisms underlying the anti-apoptotic activities of hPH against D-GalN-induced cell death in vitro were examined. Male Sprague-Dawley rats were injected with D-GaIN/LPS with or without the administration of hPH. Rats were sacrificed 24 h after D-GaIN/LPS intraperitoneal injection, and the blood and liver samples were collected for future inflammation and hepatotoxicity analyses. Changes in cell viability, apoptosis protein expression, mitochondrial mass, mitochondrial membrane potential, reactive oxygen species generation, and the levels of proteins and mRNA associated with a protective mechanism were determined in HepG2 cells pretreated with hPH for 2 h prior to D-GalN exposure. The findings suggested that hPH treatment effectively protected against D-GalN/LPS-induced hepatocyte apoptosis by reducing the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, interleukin-6, and tumor necrosis factor-α, and increasing the level of proliferating cell nuclear antigen. It was also found that hPH inhibited the apoptotic cell death induced by D-GalN. hPH activated the expression of antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, and catalase, which were further upregulated by the Kelch-like ECH2-associated protein 1-p62-nuclear factor-erythroid 2-related factor 2 pathway, a component of oxidative stress defense mechanisms. Furthermore, hPH markedly reduced cytosolic and mitochondrial reactive oxygen species and rescued mitochondrial loss and dysfunction through the reduction of damage-regulated autophagy modulator, p53, and C/EBP homologous protein. Collectively, hPH exhibited a protective role in hepatocyte apoptosis by inhibiting oxidative stress and maintaining cell homeostasis. The underlying mechanisms may be associated with the inhibition of endoplasmic reticulum stress and minimization of the autophagy progress.

Nickel oxide nanoparticles induce hepatocyte apoptosis via activating endoplasmic reticulum stress pathways in rats.

Nickel oxide nanoparticles (nano NiO) could induce hepatocyte apoptosis, while its potential mechanisms are unclear. This study aimed to explore the role of endoplasmic reticulum (ER) stress pathways in hepatocyte apoptosis induced by nano NiO. Male Wistar rats were administrated with nano NiO (0.015, 0.06, and 0.24 mg/kg b.w.) and micro NiO (0.24 mg/kg b.w.) by intratracheal instillation twice a week for 6 weeks. We measured the hepatocyte apoptosis levels by TdT-mediated dUTP nick-end labeling (TUNEL) staining, ER stress related gene and protein expression levels in rat liver. The results showed that the TUNEL positive cells increased after exposure nano NiO, hinting hepatocyte apoptosis. The up-regulated gene and protein levels of 78 kD glucose regulated protein and CCAAT/enhancer binding protein homologous protein suggested that nano NiO triggered ER stress. Nano NiO exposure contributed to the increased protein contents of inositol-requiring enzyme 1 (IRE-1)α, p-IRE-1α, X box protein-1S, pancreatic ER kinase (PERK), p-PERK, eukaryotic initiation factor-2 alpha (eIF-2α), p-eIF-2α, caspase-12, -9, and -3, implicating that nano NiO can activate the pathways of ER stress-mediated apoptosis. These findings indicate that the ER stress pathways may play an important role in hepatocyte apoptosis induced by nano NiO.

Mitochondrial activities of citrate synthase, carnitine palmitoyltransferase-1 and cytochrome C oxidase are increased during the apoptotic process in hepatocytes of a rat model of acute liver failure

To determine the roles of mitochondrial apoptosis and energy metabolism in hepatocytes during the pathogenic process of acute renal failure (ALF) by assessing disease-related differential activities of several key mitochondrial enzymes, including citrate synthase (CS), carnitine palmitoyltransferase-1 (CPT-1) and cytochrome c oxidase (COX). Thirty-two male Sprague Dawley rats were given D-galactosamine followed by and lipopolysaccharide (LPS) to induce acute liver failure and sacrificed after 4 (4 h group), 8 (8 h group) 12 (12 h group) and 24 hours (24 h group) of treatment. Eight unmodeled rats served as controls. Effects related to apoptosis were evaluated by pathological analysis of hepatic tissues and TUNEL staining. Ultrastructural changes in mitochondria were assessed by electron microscopy. The activity and expression of CS, CPT-1 and COX were measured. Hepatocyte apoptosis was present in the 4 h treatment group and was increased obviously in the 8 h treatment group. Hepatocyte necrosis was first observed in the 12 h treatment group and was significantly higher in the 24 h treatment group, with inflammatory cell invasion. Ultrastructural changes in mitochondria were present in the 4 h treatment group, and the 24 h treatment group showed mitochondria with completely destroyed outer membranes, which resulted in mitochondrial collapse. Activity and protein expression of CS, CPT-1 and COX were increased in the 4 h group (vs. controls), were at their peak in the 8 h group (CS:t =1.481, P less than 0.01; CPT-1:t =2.619, P less than 0.05; COX:t =1.014, P less than 0.01) and showed a decreasing trend in the 12 h group. In addition, the activities of CS, CPT-1 and COX were enhanced at the stage of hepatocyte apoptosis, suggesting that these enzymes were involved in the initiation and development of ALF. Energy metabolism plays an important role in hepatocyte apoptosis during ALF.

Evaluation of the diagnostic value of serum and tissue apoptotic cytokeratin-18 in patients with chronic hepatitis C

Background and study aimsHepatitis C virus (HCV) is considered the most common aetiology of chronic liver disease (CLD) in Egypt. The disease severity ranges from mild illness to cirrhosis and hepatocellular carcinoma. A role for apoptosis in liver damage caused by HCV chronic infection has been suggested. Cytokeratin 18 (CK-18) is the major intermediate filament protein in the liver and is a known caspase substrate in hepatocyte apoptosis. Therefore, we analysed the serum and tissue levels of CK-18 in patients with chronic HCV infection to evaluate its role in hepatocyte apoptosis. We also correlated CK-18 expression with the severity of hepatic pathology. Patients and methodsThis study examined 80 Egyptian patients with liver disease. There were 69 patients with chronic hepatitis C and 11 patients with hepatitis C-induced cirrhotic changes. Fifteen healthy controls were also included in the study. The levels of CK-18 fragment were quantified in paired serum and liver biopsy samples. ResultsThe serum and tissue CK-18 levels were reduced in chronic HCV patients compared to early cirrhosis patients. This result indicates that serum levels of CK-18 and the hepatic expression of CK-18 might play an important role in disease progression. The serum and tissue levels of CK-18 were significantly increased and directly correlated with inflammation severity, stage of fibrosis, and ALT levels in the chronic HCV group and the cirrhotic liver group. There was no significant difference in viral load between patient cohorts. ConclusionThe serum level and the hepatic expression of CK-18 are related to disease activity and are directly correlated with METAVIR scoring. This result suggests that serum CK-18 levels may be useful for monitoring disease activity in chronic HCV and liver cirrhosis patients.

Persistent submacular fluid diagnosed with Optical Coherence Tomography after successful scleral buckle surgery for macula-off retinal detachment

Crataegus species have been widely used in herbal medicine, especially for the hearth diseases. In the present study, the effect of Crataegus aronia var. dentata Browicz extract on partially hepatectomized rats was investigated with biochemical and TUNEL apoptosis assays. The extracts of the plant at the concentrations of 0.5 and 1 ml/100 g body weight/day were administered orally to the two experimental groups including partially hepatectomized rats for 42 days. At the end of the experimental period, animals were sacrificed, blood was collected for the assessment of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT), and the liver tissue was used for TUNEL assay. In biochemical assay, it was found a significant decrease in the levels of serum ALT and AST in the experimental groups. On the other hand, the plant extract did not cause any significant changes in the level of GGT in these groups. In apoptosis assay, TUNEL positive hepatocytes could not be detected in both experimental groups. The present findings can suggest that Crataegus aronia var. dentata Browicz extract can decrease the levels of serum ALT and AST and play a role in apoptosis of hepatocytes in the liver of partially hepatectomized rats. However, further studies are required to confirm the effects of the plant extract on hepatoprotection and apoptosis in the regenerating liver after partial hepatectomy in animal models.

The effects of Crataegus aronia var. dentata Browicz extract on biochemical indices and apoptosis in partially hepatectomized liver in rats

Crataegus species have been widely used in herbal medicine, especially for the hearth diseases. In the present study, the effect of Crataegus aronia var. dentata Browicz extract on partially hepatectomized rats was investigated with biochemical and TUNEL apoptosis assays. The extracts of the plant at the concentrations of 0.5 and 1 ml/100 g body weight/day were administered orally to the two experimental groups including partially hepatectomized rats for 42 days. At the end of the experimental period, animals were sacrificed, blood was collected for the assessment of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT), and the liver tissue was used for TUNEL assay. In biochemical assay, it was found a significant decrease in the levels of serum ALT and AST in the experimental groups. On the other hand, the plant extract did not cause any significant changes in the level of GGT in these groups. In apoptosis assay, TUNEL positive hepatocytes could not be detected in both experimental groups. The present findings can suggest that Crataegus aronia var. dentata Browicz extract can decrease the levels of serum ALT and AST and play a role in apoptosis of hepatocytes in the liver of partially hepatectomized rats. However, further studies are required to confirm the effects of the plant extract on hepatoprotection and apoptosis in the regenerating liver after partial hepatectomy in animal models.

Overexpression of Bcl-2 in hepatocytes protects against injury but does not attenuate fibrosis in a mouse model of chronic cholestatic liver disease

The role of hepatocyte apoptosis in the physiopathology of obstructive cholestasis is still controversial. Although some data have strongly suggested that hepatocellular cholestatic injury is due to Fas-mediated hepatocyte apoptosis, some others concluded that necrosis, rather than apoptosis, represents the main type of hepatocyte death in chronic cholestasis. Moreover, it has also been suggested that the reduced liver injury observed in the absence of Fas receptor after bile duct ligation was not due to lower hepatocyte apoptosis but to the indirect role of this receptor in non-hepatocytic cells such as cholangiocytes and inflammatory cells. The aim of this work was therefore to determine whether a protection against cell death limited to hepatocytes could be sufficient to reduce liver injury and delay cholestatic fibrosis. With this purpose, we performed bile duct ligation in transgenic mice overexpressing Bcl-2 in hepatocytes and in wild-type littermates. We found that, compared with necrosis, apoptosis was negligible in this model. Our results also showed that hepatocyte Bcl-2 expression protected hepatocytes against liver injury only in the early steps of the disease. This protection was correlated with reduced mitochondrial dysfunction and lipid peroxidation. However, in contrast to Fas receptor-deficient lpr mice, fibrosis progression was not hampered and liver inflammatory response was not reduced by Bcl-2 overexpression. These results therefore comfort the hypothesis that Fas-mediated apoptotic hepatocyte pathway is not a significant contributing factor to the clinical features observed in cholestasis. Moreover, in the absence of a blunted inflammatory response in transgenic mice, Bcl-2 protection against hepatocyte mitochondrial dysfunction and lipid peroxidation was not sufficient to block fibrosis progression.

Hepatitis C virus seropositivity and TNF superfamily receptors: sCD40, sFas – the new putative determinants of endothelial dysfunction in haemodialysis patients

Introduction Hepatitis C virus (HCV) infection occurs frequently among haemodialysis (HD) patients and increases the risk of atherosclerosis. CD40 and Fas belong to tumor necrosis factor receptor (TNFR) superfamily, which play a role in hepatocyte apoptosis during HCV infection. The aim of the present study was to determine whether anti-HCV-seropositivity constitutes an additional risk factor for endothelial dysfunction in HD patients, and whether sCD40 and sFas could be associated with endothelial dysfunction. Materials and methods A total of 69 stable HD patients and 28 healthy controls were included in this study. Patients were divided into anti-HCV-seropositive (HCV[+], n = 18) and anti-HCV- seronegative (HCV[-], n = 51). The plasma endothelial markers: von Willebrand factor (vWF), thrombomodulin (TM), soluble adhesion molecules – sICAM-1, sVCAM-1 and TNFRs were assayed. Results HD patients showed a significant increase in the levels of TM, sVCAM-1, sCD40 and sFas compared to controls, and all these parameters were higher in HCV[+] than in HCV[-] patients. sICAM-1 concentrations were higher in the HCV[+] group compared to controls and the HCV[-] group. vWF levels were higher in HD patients than in the controls, however there was no difference in this parameter between HCV[+] and HCV[-] group. The anti-HCV-seropositivity and sCD40 were determined as an independent variables of TM, whereas anti-HCV-seropositivity and sFas were found as independent determinants of sICAM-1 and sVCAM-1 levels. Conclusions This study showed that anti-HCV-seropositivity and TNF superfamily receptors: sCD40 and sFas are the novel determinants of the increased plasma endothelial dysfunction markers in haemodialysis patients.

TNF-α plays a role in hepatocyte apoptosis in Niemann-Pick type C liver disease

Niemann-Pick type C (NPC) is a fatal autosomal recessive lysosomal storage disease clinically characterized by neurodegeneration and liver disease. Heterogeneous mutations in the NPC1 and NPC2 genes cause impaired egress of free cholesterol from lysosomes, leading to accumulation of cholesterol and glycosphingolipids. Key features of NPC liver disease include hepatic apoptosis, inflammation, and fibrosis. It is unclear what signaling events regulate these disease processes in NPC. We hypothesize that tumor necrosis factor alpha (TNF-alpha), which is involved in both proinflammatory and apoptotic signaling cascades, is a key mediator of inflammation, apoptosis, and fibrosis in NPC liver disease. In this study, we evaluated the role of TNF-alpha signaling in NPC liver disease by utilizing NPC1-specific antisense oligonucleotides to knock down NPC1 expression in control and TNF-alpha knockout mice. In the absence of TNF-alpha, NPC1 knockdown produced liver disease with significantly less inflammation, apoptosis, and fibrosis.

Role of hepatocyte apoptosis in non-alcoholic fatty liver disease

Role of hepatocyte apoptosis in non-alcoholic fatty liver disease

Transcriptional Regulation of Cidea, Mitochondrial Cell Death-inducing DNA Fragmentation Factor α-Like Effector A, in Mouse Liver by Peroxisome Proliferator-activated Receptor α and γ

Cidea (cell death-inducing DNA fragmentation factor alpha-like effector A), a member of a novel family of proapoptotic proteins, is expressed abundantly in the brown adipose tissue of the mouse. Although Cidea mRNA is not detectable in the mouse liver, we now show that peroxisome proliferator-activated receptor (PPAR) alpha ligands Wy-14,643 and ciprofibrate increase the Cidea mRNA level in a PPARalpha-dependent manner, whereas Cidea induction in liver by PPARgamma overexpression is PPARalpha independent. Increase in Cidea mRNA content in liver did not alter the expression of uncoupling protein 1 (Ucp1) gene, which regulates thermogenesis, lipolysis, and conservation of energy. Although Cidea is considered to be a proapoptotic factor, Cidea induction in liver did not result in increased apoptosis. To elucidate the mechanism by which PPARalpha and PPARgamma regulate Cidea gene expression in the liver, we analyzed the promoter region of the Cidea gene. Three putative peroxisome proliferator response elements (PPREs) are found in the Cidea gene promoter. Transactivation, gel-shift, and chromatin immunoprecipitation assays indicated that the proximal PPRE in Cidea gene (Cidea-PPRE1 at -680/-668) is functional for both PPARalpha and -gamma. We conclude that Cidea is a novel target gene for both PPARalpha and -gamma in the liver where these two transcription factors utilize the same PPRE region for dual regulation. The induction of Cidea in liver with these PPARalpha and -gamma agonists suggests a possible role for Cidea in energy metabolism and a less likely role in hepatocyte apoptosis.

Hypoxia/Reoxygenation Up-Regulated the Expression of Death Receptor 5 and Enhanced Apoptosis in Human Hepatocyte Line

Objectives Ischemia-reperfusion injury (IRI) is a key factor that contributes to early and late dysfunction of liver graft. Although we have known that hepatocytes express death receptors for tumor necrosis factor–related apoptosis-inducing ligand (TRAIL), the effects of TRAIL on hypoxia/reoxygenation (H/R)-mediated apoptosis are unclear. This study sought to examine the effects of H/R on TRAIL cytotoxicity, as a cause of primary hepatic graft dysfunction, delayed graft refunction, and chronic graft dysfunction. Methods Using an hepatocyte H/R model in vitro to mimic IRI in the grafted liver, normal human hepatocytes HL-7702 were exposed to hypoxia for 5 hours then reoxygenated for 0, 2, 4, 6, or 20 hours. In another experiment, hepatocytes were exposed to hypoxia for 0, 2, 4, 8, or 20 hours. Expressions of TRAIL-R2/Death receptor 5 (DR5) mRNA were measured by semiquantitative reverse-transcriptase polymerase chain reactions. After 16 hours of hypoxia, human hepatocytes were treated with TRAIL in different concentrations for 5 hours. The death of hepatocytes was confirmed by flow cytometer and methyl thiazolyl tetrazolium analysis. Result After 5-hour hypoxia, the expressions of DR5 mRNA increased at all times of reoxygenation. DR5 mRNA was up-regulated from 0 hour after reoxygenation, reaching a peak value at 2 hours after reoxygenation compared with the normoxia cultured cells. Moreover, DR5 mRNA was up-regulated gradually following prolonged hypoxia. TRAIL-mediated cell killing was concentration-dependent being greater in the hypoxia treatment group compared to the normoxia group. Conclusions H/R up-regulated the expression of DR5 and enhanced TRAIL-mediated apoptosis in an human hepatocyte line. The TRAIL pathway might play a critical role in hepatocyte apoptosis induced by IRI.

Short Hairpin RNA Modulates Transforming Growth Factor β Signaling in Life-Threatening Liver Failure in Mice

Transforming growth factor beta (TGF-beta) receptor II (TGF-betaRII), which is essential for TGF-beta signaling and is involved in the causation or participates in the pathway of various human disorders, is consequently considered a key target for therapeutics and analysis of the pathophysiology associated with disruption of the TGF-beta system. In the liver, TGF-beta plays an essential role in hepatocyte apoptosis, growth inhibition, and progression of fibrogenesis. There is a critical need to introduce technology involving the TGF-beta system, such as RNA interference (RNAi), which has high potential for in vivo therapeutics and analytical activities. Here, we investigated the effect of short hairpin RNA targeting TGF-betaRII, using hepatocyte injury in human and mouse cell lines and liver injury mouse models. We demonstrated that short hairpin RNA targeting TGF-betaRII can be used to silence TGF-betaRII genes in mouse and human cell lines, and physiologic and morphologic changes in hepatocytes suffering from acute injury are spared by RNAi-mediated gene silencing of the target gene and by suppressing downstream signal transduction. Furthermore, short hairpin RNA targeting TGF-betaRII protected mice from life-threatening acute liver failure. Our study suggests the potential use of TGF-betaRII silencing by RNAi as an analytical tool for TGF-beta signaling and gene-specific therapy in human disorders.

Hepatitis C Virus Infection is Highly Correlated with Hepatocellular Apoptosis and Transforming Growth Factor‐β1 MRNA Expression in Patients with Chronic Hepatitis C

To determine whether hepatocellular apoptosis is involved in chronic liver injury in patients with chronic hepatitis C, the correlations among the rate of hepatocellular apoptosis, the rate of hepatocytes infected with hepatitis C virus (HCV) and TGF‐β1 mRNA expression, were histologically examined. HCV was visualized by in situ PCR technique. Apoptotic hepatocytes were determined by TUNEL technique. TGF‐β1 mRNA expression was quantified by Northern blotting analysis, and visualized by in situ hybridization. Fas‐antigen and proliferating cell nuclear antigen (PCNA) on hepatocytes, and α‐smooth muscle actin (αSMA) and desmin were evaluated by immunohistochemistry. In the areas of inflammation, TUNEL‐positive apoptotic hepatocytes and PCNA‐positive hepatocytes were occasionally observed around HCV‐positive hepatocyte. TGF‐β1 mRNA‐positive myofibroblast‐like Ito cells (double‐positive for αSMA and desmin) were also observed near the HCV‐positive hepatocytes. Fas‐antigen was detected on the surface of most hepatocytes in all lobules. A high correlation was found between the rate of HCV positive hepatocytes and that of apoptotic hepatocytes (r = 0.81, P < 0.05). The increase in number of HCV‐positive hepatocytes was linked to the increases in TGF‐β1 mRNA level (r = 0.79, P < 0.05) and number of TGF‐β1 mRNA‐positive Ito cells (r = 0.74, P < 0.05). These findings confirmed that the increase in HCV‐infected hepatocytes is related to the increase of hepatocellular apoptosis and the increase of TGF‐β1 mRNA in the liver of hepatitis C patients. TGF‐β1 plays an important role in apoptosis of hepatocytes infected with HCV.

P-159 Kupffer cells may play a role in apoptosis of hepatocytes in allograft rejection after rat liver transplantation

P-159 Kupffer cells may play a role in apoptosis of hepatocytes in allograft rejection after rat liver transplantation