Apoptosis in diseases of the liver

Phytotherapy-Induced Hepatocytotoxicity: A Case Report

Herbal and complementary medicine are frequently integrated with conventional medicine. We aim to report a case of severe herbal-induced liver injury (HILI) due to chronic use of green tea and protein shake. We present both clinical and laboratory evidence implicating mitochondrial toxicity and an immune response leading to a hypersensitivity reaction to the products. We have recently treated a 39-year-old man with hepatotoxicity resulting from a combination of a green tea-containing powder and a branched-chain amino acid supplement that was commenced 2 months previously. The hepatotoxicity resolved by stopping the consumption of these products and no other cause was detected. We decided to perform a lymphocyte toxicity assay (LTA) to determine if there was laboratory support for this diagnosis. LTA (% toxicity) represents the response of the mitochondria to toxic injury. To determine the role of the proinflammatory and anti-inflammatory cytokines and chemokines in the patient's reaction, we measured the level of cytokines and chemokine in the media of growing cells, exposed to each product or to a combination of products. The increased cytokines and chemokines are presented as the x-fold elevations from the upper limit of normal (ULN) for matrix metalloproteinase (MMP) (pg/mL × 1.5 ULN) and interleukin (IL)-1β (pg/mL × 1.8 ULN). Higher elevations were found for interferon (IFN)-β, IFN-γ, IL-8, IL 13, IL-15 (pg/mL × 2 ULN), regulated upon activation, normal T cell expressed and presumably secreted (RANTES) (pg/mL × 2 ULN), and nuclear factor (NFκB) (pg/mL × 3 ULN). The highest increases were for vascular endothelial factor (VEGF) (pg/mL × 10 ULN), tumor necrosis factor (TNF)-α, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) (pg/mL × 13 ULN). An examination of cellular markers showed the difference between programmed cell death (apoptosis) and cell death due to necrosis. In our case, cytokeratin-ccK18 (M-30) U/L was within the normal limits, suggesting that apoptosis was normal, while ccK8(M65) U/L was elevated at 1.5 × ULN. This result implies that upon the treatment of the patient's lymphocytes with the products, the mechanism of toxicity is necrosis. In susceptible individuals, the combination of protein and herbal tea produces mitochondrial toxicity and a strong T-lymphocyte-1 response, leading to HILI. There is a need of international reporting of adverse drug reactions by clinicians, laboratories, and pharmaceutical manufacturers to drug regulatory authorities. This requires internationally accepted standard definitions of reactions, as well as criteria for assessment.

Zafirlukast protects against hepatic ischemia-reperfusion injury in rats via modulating Bcl-2/Bax and NF-κB/SMAD-4 pathways

Hepatic ischemia/reperfusion injury (IRI) is a clinical problem commonly during liver transplantation and other liver surgery. This study aimed to evaluate the protective effect of zafirlukast (ZFK) on IR-induced hepatic injury and investigate its relevant protective mechanism. Thirty-two male Wistar albino rats were randomly allocated to four groups: sham, IRI, ZFK, and ZFK + IR groups. ZFK was administered orally in a dose of 80 mg/kg/day for 10 consecutive days. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBL) levels, and gamma glutamyl transferase (GGT) activity were estimated. Liver tissues were used to assess oxidative stress biomarkers including malondialdehyde (MDA), myeloperoxidase (MPO), nitric oxide (NOx), and reduced glutathione (GSH) contents. Inflammatory cytokines, tumor necrosis factor alpha (TNF-α) and interleukin-33 (IL-33), in addition to apoptosis biomarkers, BCL2 associated X protein (Bax), B-cell lymphoma 2 (Bcl2) and galactine-9 (GAL9) proteins were also assessed. Western blot analysis was performed for vascular endothelial growth factor (VEGF) and fibrinogen expressions. Immunohistochemical analysis for hepatic nuclear factor-kappa B (NF-κB) and SMAD-4 was done in addition to histopathological examination. Our study revealed that ZFK pre-treatment resulted in liver function restoration and oxidative stress correction. Moreover, inflammatory cytokines were significantly reduced and a remarkable reduction of apoptosis, angiogenesis, and clotting formation has been indicated. Additionally, a significant reduction in SMAD-4 and NF-kB protein expressions was observed. These results were supported by hepatic architecture improvement. Our findings revealed that ZFK possesses a potential protective effect against liver IR possibly through its antioxidant, anti-inflammatory and anti-apoptotic properties.

Ameliorative effect of bone marrow-derived mesenchymal stem cells on burn-induced hepatic and metabolic derangements in rats

AIMS

The current study aims to investigate the therapeutic potential of bone marrow-derived mesenchymal stem cells (MSCs) as a solo therapy in ameliorating both skin lesions and liver injury induced by cutaneous severe burn injury (SBI) in rats.

MAIN METHODS

In anesthetized male adult Wistar albino rats, 30 % total burn surface area and established hepatic injury was achieved via direct contact of each experimental animal's dorsum with heated metal rod (100 °C) for 10 s. On the next day following burn, human MSCs or mouse MSCs was administered locally around the burn site and intraperitonially (0.5 × 10⁶ cells/rat for each route) and outcomes were investigated at 4 and 14 days following burn induction.

KEY FINDINGS

Both types of MSCs significantly improved skin and liver histology, decreased liver enzymes, and ameliorated oxidative stress in hepatocytes of SBI-rats. Further, SBI-induced rises in hepatic apoptotic marker (caspase-3, Bax) and serum inflammatory markers (TNF-α, IL-1β, and IL-6) were reduced following either human or mouse MSC administration. In addition, MSCs augmented insulin receptor substrate-1, phosphorylated protein kinase-B (phospho-Akt), while alleviating serum glucose levels in SBI-rats. These previous effects persisted even at the 14-day time point.

SIGNIFICANCE

Following single administration, bone marrow-derived MSCs is capable of counteracting SBI-induced skin lesions as well as related hepatic complications, specifically via mitigating postburn hyperglycemia and hyperinflammation.

Inflammation and Liver Cell Death in Patients with Hepatitis C Viral Infection

Hepatitis C virus (HCV)-induced liver disease contributes to chronic hepatitis. The immune factors identified in HCV include changes in the innate and adaptive immune system. The inflammatory mediators, known as "inflammasome", are a consequence of the metabolic products of cells and commensal or pathogenic bacteria and viruses. The only effective strategy to prevent disease progression is eradication of the viral infection. Immune cells play a pivotal role during liver inflammation, triggering fibrogenesis. The present paper discusses the potential role of markers in cell death and the inflammatory cascade leading to the severity of liver damage. We aim to present the clinical parameters and laboratory data in a cohort of 88 HCV-infected non-cirrhotic and 25 HCV cirrhotic patients, to determine the characteristic light microscopic (LM) and transmission electron microscopic (TEM) changes in their liver biopsies and to present the link between the severity of liver damage and the serum levels of cytokines and caspases. A matched HCV non-infected cohort was used for the comparison of serum inflammatory markers. We compared the inflammation in HCV individuals with a control group of 280 healthy individuals. We correlated the changes in inflammatory markers in different stages of the disease and the histology. We concluded that the serum levels of cytokine, chemokine, and cleaved caspase markers reveal the inflammatory status in HCV. Based upon the information provided by the changes in biomarkers the clinician can monitor the severity of HCV-induced liver damage. New oral well-tolerated treatment regimens for chronic hepatitis C patients can achieve cure rates of over 90%. Therefore, using the noninvasive biomarkers to monitor the evolution of the liver damage is an effective personalized medicine procedure to establish the severity of liver injury and its repair.

The History of Alcoholic Liver Disease: From an Unrecognized Disease to One of the Most Frequent Diseases in Hepatology

This review describes the history of alcoholic liver disease from the beginning of the 1950s until now. It details how the hepatotoxicity of alcohol was discovered by epidemiology and basic research primarily by using new feeding techniques in rodents and primates. The article also recognizes the pioneering work of scientists who contributed to the understanding of the pathophysiology of alcoholic liver disease. In addition, clinical aspects, such as the development of diagnostics and treatment options for alcoholic liver disease, are discussed. Up-to-date knowledge of the mechanism of the disease in 2020 is presented.

Time-Course Changes of Serum Keratin Concentrations after Liver Transplantation: Contrasting Results of Keratin-18 and Keratin-19 Fragments

Objective

Under normal conditions, adult hepatocytes express only keratin-8 (K8) and keratin-18 (K18), whereas cholangiocytes also express K19. In this study, we delineate the pattern of normal time-course changes in serum K19 and K18 levels after liver transplantation. Patients and Methods. Serum levels of the K19 fragment CYFRA 21-1 and the K18 fragments tissue polypeptide specific antigen (TPS) and M30 (a neoepitope that is generated after caspase cleavage during apoptosis) were measured at baseline and at regular intervals (up to 6 months) after liver transplantation in 11 adult patients.

Results

There was a gradual decrease in serum K19 concentrations from baseline values after transplantation, following a time-course pattern similar to that of serum bilirubin. In contrast, serum concentrations of K18 fragments increased markedly shortly after transplantation and gradually decreased thereafter, following a time-course pattern similar to that of serum transaminases. The increase in TPS tended to occur earlier than that in M30, suggesting an initial predominance of hepatocyte necrosis followed by a predominance of apoptosis in the first days after transplantation. Five patients presented posttransplant complications (acute rejection in three cases and HCV recurrence in two cases). An early increase in serum K19 concentrations was observed in all cases. An increase in serum concentrations of K18 fragments (M30 and TPS) was observed in the two cases with HCV recurrence and was more variable in the three cases with acute rejection.

Conclusions

Serum concentrations of K19 and K18 fragments follow a dissimilar pattern of time-course changes after liver transplantation. The diagnostic value of variations in these normal patterns should be addressed in future studies.

Modulation of rifampicin-induced hepatotoxicity using poly(lactic-co-glycolic acid) nanoparticles: a study on rat and cell culture models

Aim: Hepatotoxicity is the most serious adverse effect of rifampicin (RIF). We aimed to investigate the potential hepatoprotective effect of mannose-functionalized poly(lactic-co-glycolic acid)(PLGA)/RIF nanoparticles (NPs) in rats as a possible promising approach to minimize RIF-induced hepatotoxicity. Materials & methods: Mannose-functionalized PLGA/RIF NPs were fabricated and characterized in vitro, then the hepatoprotective effect of optimized NPs was studied on rat and cell culture models. Results: Following intraperitoneal administration of RIF NPs into rats, highly significant differences in levels of serum transaminases and oxidative stress markers, associated with significant differences in expression of Bax and Bcl-2 genes between NP- and free RIF-treated groups, revealing the hepatoprotective potential of NPs. Conclusion: RIF NPs may represent a promising therapeutic approach for tuberculosis via reducing dose frequency and consequently, RIF-induced hepatotoxicity.

Activation of pCREB/Nrf-2 signaling mediates re-positioning of liraglutide as hepato-protective for methotrexate -induced liver injury (MILI)

Methotrexate (MTX) is commonly used to treat several types of cancer and autoimmune diseases. However, there is increasing concern over its organs toxicities particularly liver toxicity. Liraglutide, a glucagon like peptide-1 agonist, possesses antioxidant and anti-inflammatory features. This study aimed to explore the potential protective effect of liraglutide pre-treatment in ameliorating MTX-induced hepatotoxicity and to further investigate the underlying mechanisms. Rats received 1.2 mg/kg liraglutide intraperitoneal twice daily for 7 days before MTX. Results revealed that liraglutide significantly decreased activities of liver enzymes and oxidative stress in hepatocytes. Furthermore, NF-kB expression and related inflammatory markers (TNF-α, COX-2 and IL-6) were reduced in the pre-treatment group of liraglutide. These data validate the advantageous effects of liraglutide in MTX hepatotoxic animals. In addition, liraglutide increased the expression of the antioxidant transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf-2), along with the transcription of downstream phosphorylated cAMP response element-binding protein (pCREB) which increases the activity of Nrf-2. Additionally, caspase-3 expression/activity and BAX/Bcl-2 ratio were decreased following liraglutide pre-treatment. In conclusion, it was confirmed that liraglutide enhanced the antioxidant activity of liver cells by activating the Nrf-2 and pCREB signaling, thereby, reducing liver cell inflammation and apoptosis induced by MTX.

The role of apoptosis in acetaminophen hepatotoxicity

Although necrosis is recognized as the main mode of cell death induced by acetaminophen (APAP) overdose in animals and humans, more recently an increasing number of publications, especially in the herbal medicine and dietary supplement field, claim an important contribution of apoptotic cell death in the pathophysiology. However, most of these conclusions are based on parameters that are not specific for apoptosis. Therefore, the objective of this review was to re-visit the key signaling events of receptor-mediated apoptosis and APAP-induced programmed necrosis and critically analyze the parameters that are being used as evidence for apoptotic cell death. Both qualitative and quantitative comparisons of parameters such as Bax, Bcl-2, caspase processing and DNA fragmentation in both modes of cell death clearly show fundamental differences between apoptosis and cell death induced by APAP. These observations together with the lack of efficacy of pan-caspase inhibitors in the APAP model strongly supports the conclusion that APAP hepatotoxicity is dominated by necrosis or programmed necrosis and does not involve relevant apoptosis. In order not to create a new controversy, it is important to understand how to use these "apoptosis" parameters and properly interpret the data. These issues are discussed in this review.

Recent insights into mitochondrial targeting strategies in liver transplantation

Ischemia/reperfusion (I/R) injury in liver transplantation can disrupt the normal activity of mitochondria in the hepatic parenchyma. This potential dysfunction of mitochondria after I/R injury could be responsible for the initial poor graft function or primary nonfunction observed after liver transplantation. Thus, determining the mechanisms that lead to human hepatic mitochondrial dysfunction might contribute to improving the outcome of liver transplantation. Furthermore, early identification of novel prognostic factors involved in I/R injury could serve as a key endpoint to predict the outcome of liver grafts and also to promote the early adoption of novel strategies that protect against I/R injury. Here, we briefly review recent advances in the study of mitochondrial dysfunction and I/R injury, particularly in relation to liver transplantation. Next, we highlight various pharmacological therapeutic strategies that could be applied, and discuss their relationship to relevant mitochondrion-related processes and targets. Lastly, we note that although considerable progress has been made in our understanding of I/R injury and mitochondrial dysfunction, further investigation is required to elucidate the cellular and molecular mechanisms underlying these processes, thereby identifying biomarkers that can help in evaluating donor organs.

Soluble Asialoglycoprotein Receptors Reflect the Apoptosis of Hepatocytes

Cell death is thought to take place through at least two distinct processes: apoptosis and necrosis. There is increasing evidence that dysregulation of the apoptotic program is involved in liver diseases. However, there is no method to simply evaluate apoptosis in the liver tissue at present. It has been reported that the expression of asialoglycoprotein receptors (AGPRs) increases with apoptosis, but there is no report until now that investigates the influence of soluble AGPRs on apoptosis of hepatocytes. Soluble AGPRs have been reported to be present in human serum under physiological conditions. In the present study, in order to investigate the correlation between apoptosis of hepatocytes and soluble AGPR, mouse soluble AGPRs were detected using SDS-PAGE and Western blot analysis was conducted using anti-extracellular mouse hepatic lectin-1 (Ex-MHL-1) antiserum (polyclonal rabbit serum). The mouse soluble AGPRs were present in culture medium and mouse serum when hepatocytes were damaged. The soluble AGPRs increased proportionately, as the number of dead hepatocytes increased. In addition, soluble AGPRs existed more when apoptotic cell death was observed in in vitro and in vivo than when necrotic cell death was observed. The extracellular moiety of MHL-1 exists in the culture medium and mouse serum as a soluble AGPR, but the detailed mechanism of releasing soluble AGPR from hepatocytes has not been revealed yet. We described the first evidence for the relation between quantity of soluble AGPRs with two kinds of cell death: necrosis and apoptosis. Based on the results of our study, soluble AGPRs might become a new marker of apoptosis in the liver tissue and be useful for clinical diagnosis and treatment for liver diseases.

TNF and IL-18 cytokines may regulate liver fat storage under homeostasis conditions

The inflammation induced by obesogenic diets is associated with deposition of fat in the liver. On the other hand, anti-inflammatory and immunosuppressive therapies may impact in body fat storage and in liver lipid dynamics. It is important to study specific inflammatory mediators in this context, since their role on hepatic damage is not fully clarified. This study aimed to evaluate the role of interleukin (IL)-18 and tumor necrosis factor (TNF) receptor in liver dysfunction induced by diet. Male C57BL/6 wild-type (WT), IL-18, and TNF receptor 1 knockout mice (IL-18^-/- and TNFR1^-/-) were divided according to the experimental diets: chow diet or a high-refined carbohydrate-containing diet. Alanine aminotransferase was quantified by colorimetric analysis. Total fat content in the liver was determined by Folch methods. Levels of TNF, IL-6, IL-4, and IL-13 in liver samples were measured by ELISA assay. IL-18 and TNFR knockout mice fed with chow diet showed higher liver triglycerides deposition than WT mice fed with the same diet (WT: 131.9 ± 24.5; IL-18^-/-: 239.4 ± 38.12*; TNF^-/-: 179.6 ± 50.45*; *P < 0.01). Furthermore, these animals also showed a worse liver histopathological score and lower levels of TNF, IL-6, IL-4, and IL-13 in the liver. Interestingly, treatment with a high-carbohydrate diet did not exacerbate liver damage in IL-18^-/- and TNFR1^-/- mice. Our data suggest that IL-18 and TNF may be involved on hepatic homeostasis mainly in a context of a healthy diet.

Lipoic acid attenuates Aroclor 1260-induced hepatotoxicity in adult rats

The present study was aimed to investigate the mechanistic aspect of Aroclor 1260-induced hepatotoxicity and its protection by lipoic acid. The adult male Albino rats were divided into six groups. Group I served as control. Group II received lipoic acid (35 mg/kg/day). Aroclor 1260 was given to rats by oral gavage at doses 20, 40, or 60 mg/kg/day (Groups III, IV, and V, respectively). Group VI was pretreated with lipoic acid (35 mg/kg/day) 24 h before Aroclor 1260 (40 mg/kg/day). Treatment in all groups was continued for further 15 consecutive days. Serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase activities and total bilirubin, total cholesterol, and triglycerides were significantly increased while total protein, total albumin, and high-density lipoprotein were significantly decreased. Hydrogen peroxide production and lipid peroxidation were significantly increased while superoxide dismutase and catalase activities and reduced glutathione (GSH) content was significantly decreased in liver. Caspase-3 & -9 activities were significantly increased in liver. Lipoic acid pretreatment significantly reverted all these abnormalities toward their normal levels. In conclusion, Aroclor 1260 induced liver dysfunction, at least in part, by induction of oxidative stress. Apoptotic effect of hepatic cells is involved in Aroclor 1260-induced liver injury. Lipoic acid could protect rats against Aroclor 1260-induced hepatotoxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 913-922, 2016.

Functional genetics-directed identification of novel pharmacological inhibitors of FAS- and TNF-dependent apoptosis that protect mice from acute liver failure

shRNA-mediated gene-silencing technology paired with cell-based functional readouts reveals potential targets directly, providing an opportunity to identify drugs against the target without knowing the precise role of the target in the pathophysiological processes of interest. By screening a lentiviral shRNA library targeting for major components of human signaling pathways and known drug targets, we identified and validated both canonical as well as 52 novel mediators of FAS and TNF ligand-induced apoptosis. Presence of potential therapeutic targets among these mediators was confirmed by demonstration of in vivo activity of siRNAs against four identified target candidates that protected mice from acute liver failure (ALF), a life-threatening disease with known involvement of death receptor (DR)-mediated apoptosis. Network-based modeling was used to predict small-molecule inhibitors for several candidate apoptosis mediators, including somatostatin receptor 5 (SSTR5) and a regulatory subunit of PP2A phosphatase, PPP2R5A. Remarkably, pharmacological inhibition of either SSTR5 or PPP2R5A reduced apoptosis induced by either FASL or TNF in cultured cells and dramatically improved survival in several mouse models of ALF. These results demonstrate the utility of loss-of-function genetic screens and network-based drug-repositioning methods for expedited identification of targeted drug candidates and revealed pharmacological agents potentially suitable for treatment of DR-mediated pathologies.

Inhibition of Hepatocyte Apoptosis: An Important Mechanism of Corn Peptides Attenuating Liver Injury Induced by Ethanol

In this study, the effects of mixed corn peptides and synthetic pentapeptide (QLLPF) on hepatocyte apoptosis induced by ethanol were investigated in vivo. QLLPF, was previously characterized from corn protein hydrolysis, which had been shown to exert good facilitating alcohol metabolism activity. Mice were pre-treated with the mixed corn peptides and the pentapeptide for 1 week and then treated with ethanol. After treatment of three weeks, the biochemical indices and the key ethanol metabolizing enzymes, the serum TNF-α, liver TGF-β1 concentrations and the protein expressions related to apoptosis were determined. We found that the Bcl-2, Bax and cytochrome c expressions in the intrinsic pathway and the Fas, FasL and NF-κB expressions in the extrinsic pathway together with higher TNF-α and TGF-β1 concentrations were reversed compared with the model group by both the mixed corn peptides and the pentapeptide. The activation of caspase3 was also suppressed. Additionally, apoptosis was further confirmed with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the TUNEL assay demonstrated peptides suppressed hepatocyte apoptosis. Our results suggest that apoptosis induced by ethanol is alleviated in response to the treatment of corn peptides, potentially due to reversing the related protein expression.

Glucagon-like peptide-2 exhibits protective effect on hepatic ischemia-reperfusion injury in rats

Glucagon-like peptide-2 (GLP-2) has potent anti-inflammatory effects and protects against experimental ischemia/reperfusion (I/R) injury in pulmonary, intestinal, and myocardial tissue. However, its protective abilities against I/R injury in the liver are unknown. We investigated the potential role of GLP-2 pretreatment on hepatic I/R injury in rats. A total of 24 rats were randomly divided into three groups (n = 8). The first group was the control group; the second group was the vehicle-treated hepatic ischemia/reperfusion (HIR, vehicle saline-treated) group; and the third group was the GLP-2 pretreated I/R (GLP2-IR) group. Each rat in the third group was intraperitoneally administered 5 µg GLP-2 for 5 d before the procedure. A portal triad was created to induce ischemia with a vascular atraumatic clamp. After 40 min, the clamp was released to initiate hepatic reperfusion for 6 h. Blood samples and tissue specimens from the liver were obtained. Alanine aminotransferase, aspartate aminotransferase, and total bilirubin levels significantly increased in the salinetreated HIR group (P < 0.001), whereas GLP-2 pretreatment significantly decreased their levels (P < 0.01). Our data suggested that GLP-2 pretreatment may have a protective effect on liver I/R injury. However, dose-response studies are necessary to determine the most effective dose.

Cryptotanshinone Ameliorates Hepatic Normothermic Ischemia and Reperfusion Injury in Rats by Anti-mitochondrial Apoptosis

Cryptotanshinone (CT), isolated from the dried roots of Salvia militorrhiza, has been reported to have protective effects on myocardial and cerebral ischemia/reperfusion (I/R) injury both in vitro and in vivo. However, its effects and underlying mechanism on hepatic I/R injury remain unclear. To investigate its effects on hepatic I/R injury, thirty male Sprague-Dawley rats were randomized into 3 groups: a sham group, a vehicle-treated hepatic I/R group and a CT-treated (50 mg/kg) group. The hepatic I/R and CT-treated groups were subjected to 60 min of normothermic ischemia of the left lateral lobe of the liver, followed by 4 h of reperfusion. The animals were then sacrificed to collect the serum and the left liver lobe for assay. Hepatic function was protected, as evidenced by significantly reduced alanine aminotransferase (ALT), aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in the CT-treated group as compared with I/R group. The terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) demonstrated significantly decreased apoptosis in the CT-administration animals. Western blotting demonstrated upregulation of the proapoptotic protein Bcl-2, as well as decreased levels of the activated form of caspase-3 and the cleaved form of its substrate, poly(ADP-ribose) polymerase (PARP) in the CT-treated group compared with those of the I/R group. In addition, the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs) was inhibited by CT. Our data suggest that CT attenuates hepatic I/R injury by inhibiting the intrinsic pathway of apoptosis, mediated partly through the inhibition of JNK and p38 MAPK phosporylation.

Rhein Elicits In Vitro Cytotoxicity in Primary Human Liver HL-7702 Cells by Inducing Apoptosis through Mitochondria-Mediated Pathway

Objective. To study rhein-induced apoptosis signaling pathway and to investigate its molecular mechanisms in primary human hepatic cells. Results. Cell viability of HL-7702 cells treated with rhein showed significant decrease in dose-dependent manner. Following rhein treatment (25 μM, 50 μM, and 100 μM) for 12 h, the detection of apoptotic cells was significantly analyzed by flow cytometry and nuclear morphological changes by Hoechst 33258, respectively. Fatty degeneration studies showed upregulation level of the relevant hepatic markers (P < 0.01). Caspase activities expressed significant upregulation of caspase-3, caspase-9, and caspase-8. Moreover, apoptotic cells by rhein were significantly inhibited by Z-LEHD-FMK and Z-DEVD-FMK, caspase-9 inhibitor, and caspase-3 inhibitor, respectively. Overproduction of reactive oxygen species, lipid peroxidation, and loss of mitochondrial membrane potential were detected by fluorometry. Additionally, NAC, a ROS scavenger, significantly attenuated rhein-induced oxidative damage in HL-7702 cells. Furthermore, real-time qPCR results showed significant upregulation of p53, PUMA, Apaf-1, and Casp-9 and Casp-3 mRNA, with no significant changes of Fas and Cytochrome-c. Immunoblotting revealed significant Cytochrome-c release from mitochondria into cytosol and no change in Fas expression. Conclusion. Taken together, these observations suggested that rhein could induce apoptosis in HL-7702 cells via mitochondria-mediated signal pathway with involvement of oxidative stress mechanism.

Anti-apoptotic therapeutic approaches in liver diseases: do they really make sense?

A variety of data suggesting apoptotic cell death as a key feature of liver injury stimulated researchers to investigate the therapeutic potential of anti-apoptotic strategies in experimental models. However, the overestimated role of apoptotic cell death in liver injury has tempered the clinical translation of the protection afforded by anti-apoptotic regimes in experimental models. Thus, the hope for apoptosis modulation as potential treatment strategy for injured liver in humans could not be confirmed. Herein, we evaluated the degree of apoptosis in different hepatic stress models which are relevant for the human pathophysiology. Using morphological criteria of apoptosis, caspase-3 activation as well as TUNEL assay in combination with a positive control of apoptosis in liver injury, we quantified apoptotic cell death discriminating between parenchymal and non-parenchymal cells and confirmed these results by cleaved caspase-3 and PARP-1 protein expression. Discussing our findings and relating them to the existing literature on the potential role of apoptotic cell death, we strongly recommend reconsidering anti-apoptotic strategies to ameliorate liver injury efficiently.

Targeting apoptosis in autoimmune hepatitis

Apoptosis is the predominant mechanism of liver cell death in autoimmune hepatitis, and interventions that can modulate this activity are emerging. The aim of this review was to describe the apoptotic mechanisms, possible aberrations, and opportunities for intervention in autoimmune hepatitis. Studies cited in PubMed from 1972 to 2014 for autoimmune hepatitis, apoptosis in liver disease, apoptosis mechanisms, and apoptosis treatment were examined. Apoptosis is overactive in autoimmune hepatitis, and the principal pathway of cell death is receptor mediated. Surface death receptors are activated by extrinsic factors including liver-infiltrating cytotoxic T cells and the cytokine milieu. The executioner caspases 3 and 7 cleave nuclear deoxyribonucleic acid, and the release of apoptotic bodies can stimulate inflammatory, immune, and fibrotic responses. Changes in mitochondrial membrane permeability can be initiated by caspase 8, and an intrinsic pathway of apoptosis can complement the extrinsic pathway. Defects in the apoptosis of activated effector cells can prolong their survival and sustain the immune response. Caspase inhibitors have been used in diverse experimental and human diseases to retard apoptosis. Oligonucleotides that inhibit the signaling of toll-like receptors can limit the presentation of auto-antigens, and inhibitors of apoptosis that extend the survival of effector cells can be blocked by antisense oligonucleotides. Mechanisms that enhance the clearance of apoptotic bodies and affect key signaling pathways are also feasible. Interventions that influence the survival of liver and effector cells by altering their apoptosis are candidates for study in autoimmune hepatitis.

N-acetylcysteine attenuates ischemia-reperfusion-induced apoptosis and autophagy in mouse liver via regulation of the ROS/JNK/Bcl-2 pathway

Background

Hepatic ischemia–reperfusion injury (HIRI) remains a pivotal clinical problem after hemorrhagic shock, transplantation, and some types of toxic hepatic injury. Apoptosis and autophagy play important roles in cell death during HIRI. It is also known that N-acetylcysteine (NAC) has significant pharmacologic effects on HIRI including elimination of reactive oxygen species (ROS) and attenuation of hepatic apoptosis. However, the effects of NAC on HIRI-induced autophagy have not been reported. In this study, we evaluated the effects of NAC on autophagy and apoptosis in HIRI, and explored the possible mechanism involved.

Methods

A mouse model of segmental (70%) hepatic warm ischemia was adopted to determine hepatic injury. NAC (150 mg/kg), a hepatoprotection agent, was administered before surgery. We hypothesized that the mechanism of NAC may involve the ROS/JNK/Bcl-2 pathway. We evaluated the expression of JNK, P-JNK, Bcl-2, Beclin 1 and LC3 by western blotting and immunohistochemical staining. Autophagosomes were evaluated by transmission electron microscopy (TEM).

Results

We found that ALT, AST and pathological changes were significantly improved in the NAC group. Western blotting analysis showed that the expression levels of Beclin 1 and LC3 were significantly decreased in NAC-treated mice. In addition, JNK, p-JNK, Bax, TNF-α, NF-κB, IL2, IL6 and levels were also decreased in NAC-treated mice.

Conclusion

NAC can prevent HIRI-induced autophagy and apoptosis by influencing the JNK signal pathway. The mechanism is likely to involve attenuation of JNK and p-JNK via scavenged ROS, an indirect increase in Bcl-2 level, and finally an alteration in the balance of Beclin 1 and Bcl-2.

Protective effect of linarin against D-galactosamine and lipopolysaccharide-induced fulminant hepatic failure

Linarin was isolated from Chrysanthemum indicum L. Fulminant hepatic failure is a serious clinical syndrome that results in massive inflammation and hepatocyte death. Apoptosis is an important cellular pathological process in d-galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury, and regulation of liver apoptosis might be an effective therapeutic method for fulminant hepatic failure. This study examined the cytoprotective mechanisms of linarin against GalN/LPS-induced hepatic failure. Mice were given an oral administration of linarin (12.5, 25 and 50mg/kg) 1h before receiving GalN (800 mg/kg)/LPS (40 μg/kg). Linarin treatment reversed the lethality induced by GalN/LPS. After 6h of GalN/LPS injection, the serum levels of alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor (TNF)-α, interleukin-6 and interferon-γ were significantly elevated. GalN/LPS increased toll-like receptor 4 and interleukin-1 receptor-associated kinase protein expression. These increases were attenuated by linarin. Linarin attenuated the increased expression of Fas-associated death domain and caspase-8 induced by GalN/LPS, reduced the cytosolic release of cytochrome c and caspase-3 cleavage induced by GalN/LPS, and reduced the pro-apoptotic Bim phosphorylation induced by GalN/LPS. However, linarin increased the level of anti-apoptotic Bcl-xL and phosphorylation of STAT3. Our results suggest that linarin alleviates GalN/LPS-induced liver injury by suppressing TNF-α-mediated apoptotic pathways.

Osteopontin deficiency aggravates hepatic injury induced by ischemia-reperfusion in mice

Osteopontin (OPN) is a multifunctional protein involved in hepatic steatosis, inflammation, fibrosis and cancer progression. However, its role in hepatic injury induced by ischemia–reperfusion (I–R) has not yet been investigated. We show here that hepatic warm ischemia for 45 min followed by reperfusion for 4 h induced the upregulation of the hepatic and systemic level of OPN in mice. Plasma aspartate aminotransferase and alanine aminotransferase levels were strongly increased in Opn^−/− mice compared with wild-type (Wt) mice after I–R, and histological analysis of the liver revealed a significantly higher incidence of necrosis of hepatocytes. In addition, the expression levels of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNFα), interleukin 6 (IL6) and interferon-γ were strongly upregulated in Opn^−/− mice versus Wt mice after I–R. One explanation for these responses could be the vulnerability of the OPN-deficient hepatocyte. Indeed, the downregulation of OPN in primary and AML12 hepatocytes decreased cell viability in the basal state and sensitized AML12 hepatocytes to cell death induced by oxygen–glucose deprivation and TNFα. Further, the downregulation of OPN in AML12 hepatocytes caused a strong decrease in the expression of anti-apoptotic Bcl2 and in the ATP level. The hepatic expression of Bcl2 also decreased in Opn^−/− mice versus Wt mice livers after I–R. Another explanation could be the regulation of the macrophage activity by OPN. In RAW macrophages, the downregulation of OPN enhanced iNOS expression in the basal state and sensitized macrophages to inflammatory signals, as evaluated by the upregulation of iNOS, TNFα and IL6 in response to lipopolysaccharide. In conclusion, OPN partially protects from hepatic injury and inflammation induced in this experimental model of liver I–R. This could be due to its ability to partially prevent death of hepatocytes and to limit the production of toxic iNOS-derived NO by macrophages.

Nature and mechanisms of hepatocyte apoptosis induced by D-galactosamine/lipopolysaccharide challenge in mice

Apoptosis plays a role in the normal development of liver. However, overactivation thereof may lead to hepatocellular damage. The aim of this study was to assess d-galactosamine (d-GalN)/lipopolysaccharide (LPS)-induced hepatocyte apoptotic changes in mice and clarify the mechanisms involved in this process. DNA ladder detection was employed to determine the induction condition of hepatic apoptosis. An initial test indicated that typical hepatocyte apoptosis was observed at 6–10 h after the intraperitoneal injection of d-GalN (700 mg/kg) and LPS (10 μg/kg). Subsequently, we evaluated hepatocyte apoptosis at 8 h after administering d-GalN/LPS by histopathological analysis, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) detection, flow cytometry and electron microscopy analysis. To clarify the apoptosis-related gene expression, the expression levels of tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), caspase-3, and Fas/Fas ligand (FasL) were determined by serum enzyme immunoassay, immunohistochemistry and western blot analysis. Strong apoptotic positive signals following d-GalN/LPS injection were observed from the results of the serum analysis, histopathological and immunohistochemical analyses, DNA ladder detection, TUNEL detection, flow cytometry and electron microscopy analysis. Additionally, apoptotic hepatocytes were mainly at the late stage of cell apoptosis. The expression of TNF-α, TGF-β1, caspase-3 and Fas/FasL was significantly increased. In conclusion, this study evaluated the d-GalN/LPS-induced hepatocyte apoptotic changes and clarified the apoptosis-related gene expression in mice. The hepatocyte apoptosis induced by d-GalN/LPS may be mainly regulated by the death receptor pathway. TGF-β signaling pathway may also play a vital role in this process of hepatocyte apoptosis.

Bioluminescence imaging of caspase-3 activity in mouse liver

Apoptosis is an essential process for the maintenance of liver physiology. The ability to noninvasively image apoptosis in livers would provide unique insights into its role in liver disease processes. In the present work, we established a stable mouse model by hydrodynamics methods to study the activity of caspase-3 and evaluate the effect of the apoptosis inhibitors in mouse livers under true physiological conditions by bioluminescence imaging. The reporter plasmid attB-ANLuc(DEVD)BCLuc that contains fragment of attB and ANLuc(DEVD)BCLuc was codelivered with the mouse-codon optimized φC31 (φC31o) integrase plasmids specifically to mouse liver by hydrodynamic injection procedure. Then, φC31o integrase mediated intramolecular recombination between wild-type attB and attP site in mice, and thus the reporter expression cassette attB-ANLuc(DEVD)BCLuc was integrated permanently into mouse liver chromosome. We used these mice to characterize in vivo activation of caspase-3 upon treatment with LPS/D-GalN. Our data show that liver apoptosis could be reflected by the activity of luciferase. The shRNA targeting caspase-3 protein or apoptosis inhibitors could effectively downregulate luciferase activity in vivo. Also, this model could be used to measure caspase-3 activation during inflammatory and infectious events in vivo as verified by infected with MHV-3. This model could be used for screening anti-apoptosis compounds target mouse livers.

Ethyl pyruvate ameliorates hepatic ischemia-reperfusion injury by inhibiting intrinsic pathway of apoptosis and autophagy

Background. Hepatic ischemia-reperfusion (I/R) injury is a pivotal clinical problem occurring in many clinical conditions such as transplantation, trauma, and hepatic failure after hemorrhagic shock. Apoptosis and autophagy have been shown to contribute to cell death in hepatic I/R injury. Ethyl pyruvate, a stable and simple lipophilic ester, has been shown to have anti-inflammatory properties. In this study, the purpose is to explore both the effect of ethyl pyruvate on hepatic I/R injury and regulation of intrinsic pathway of apoptosis and autophagy. Methods. Three doses of ethyl pyruvate (20 mg/kg, 40 mg/kg, and 80 mg/kg) were administered 1 h before a model of segmental (70%) hepatic warm ischemia was established in Balb/c mice. All serum and liver tissues were obtained at three different time points (4 h, 8 h, and 16 h). Results. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and pathological features were significantly ameliorated by ethyl pyruvate (80 mg/kg). The expression of Bcl-2, Bax, Beclin-1, and LC3, which play an important role in the regulation of intrinsic pathway of apoptosis and autophagy, was also obviously decreased by ethyl pyruvate (80 mg/kg). Furthermore, ethyl pyruvate inhibited the HMGB1/TLR4/ NF-κb axis and the release of cytokines (TNF-α and IL-6). Conclusion. Our results showed that ethyl pyruvate might attenuate to hepatic I/R injury by inhibiting intrinsic pathway of apoptosis and autophagy, mediated partly through downregulation of HMGB1/TLR4/ NF-κb axis and the competitive interaction with Beclin-1 of HMGB1.

Mechanism for hepato-protective action of Liangxue Huayu Recipe (LHR): blockade of mitochondrial cytochrome c release and caspase activation

ETHNOPHARMACOLOGICAL RELEVANCE

Liangxue Huayu Recipe (LHR) as a classical prescription is clinically employed to treat liver diseases in traditional Chinese medicine.

AIM OF STUDY

In this study, we attempt to show that LHR attenuates hepatocyte apoptosis and hepatic injury induced by lipopolysaccharide (LPS) and D-galactosamine (GalN) in rats. The present study was also designed to examine whether LHR had the protective effects on d-GalN and tumor necrosis factor-α (TNF-α)-treated human L02 hepatocytes and its possible association with the mitochondrial pathway.

MATERIALS AND METHODS

LHR is composed of three traditional Chinese medicines: Herba Rehmannia, Rhubarb and Radix Paeoniae Rubra. LHR at 541, 1082 and 2164 mg/kg was orally administered to model and normal rats for 7 days. The effects of LHR on serum levels of liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were measured. Hepatocyte apoptosis in vivo was assessed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) method. Apoptosis in vitro and related morphological changes of human L02 hepatocytes were determined by high content screening (HCS) assay. The expression levels of Bcl-2, Bax and cytochrome c were detected by Western-blot analysis in L02 cells. In addition, the activities of caspase-3 and caspase-9 were tested by enzyme-linked immunosorbent detector.

RESULTS

It revealed that LHR pretreatment effectively ameliorated the GalN/LPS-induced elevation of serum ALT and AST levels, and attenuated hepatocyte apoptosis in the rat model characterized by the addition of GalN/LPS. In subsequent experiments in vitro, LHR also attenuated GalN/TNF-α-induced apoptosis in human L02 hepatocytes. Furthermore, LHR improved the mitochondrial function, inhibited the upregulation of Bax/Bcl-2 protein ratio, decreased the release of cytochrome c from the mitochondria into the cytosol, as well as inhibited caspase-3 and caspase-9 activation in this cell model.

CONCLUSIONS

These results indicate that LHR is effective in attenuating hepatocyte apoptosis both in vivo and in vitro, and this effect is partly mediated through the activation of the mitochondrial pathway and subsequent regulation of particular pro-apoptotic gene expression.

Geraniin and amariin, ellagitannins from Phyllanthus amarus, protect liver cells against ethanol induced cytotoxicity

Ethanol mediated free radical generation plays an important role in the pathogenesis of liver injuries and alcoholic liver diseases. In the present study two ellagitannins namely geraniin and amariin isolated from Phyllanthus amarus were examined for their ability to protect mouse liver slices against ethanol induced toxicity and possible mechanism of its protection. Oxidative stress markers such as, lipid peroxidation, protein carbonyl formation, amount of 8-hydroxy-2-deoxyguanosine and antioxidant enzymes levels were measured using specific biochemical assays. Poly (ADP-ribose) polymerase (PARP), Bax and Bcl2 were checked to assess the induction of apoptosis using western blots. The results showed that geraniin and amariin protected mouse liver slices against ethanol induced cytotoxicity. Both compounds inhibited oxidation of lipid, protein and formation of 8-hydroxy-2-deoxyguanosine, all of which were found to be elevated on exposure to ethanol. These compounds restored the antioxidant enzymes altered on ethanol exposure. Compounds also inhibited the cleavage of PARP and bax and restored Bcl2, induced on exposure to ethanol. In summary, both ellagitannins effectively protected mouse liver slices against ethanol induced cytotoxicity and apoptosis by reducing oxidative damage to biological molecules and modulating Bax/Bcl-2 ratio respectively, thus minimizing liver injury.

Role of naofen in apoptosis of hepatocytes induced by lipopolysaccharide through mitochondrial signaling in rats

AIM

  Lipopolysaccharide (LPS) causes apoptosis of hepatocytes, which is probably mediated by inflammatory substances released from Kupffer cells (KCs). Recently, we have reported that naofen, a newly found intracellular WD40-repeat protein, has a role in inducing the apoptosis in HEK293 cells. Hence, the present study was undertaken to investigate a role of naofen in the LPS-induced apoptosis of rat hepatocytes.

METHODS

  Rats were treated with i.v. injections of LPS, and livers were extirpated to evaluate expression of naofen and apoptosis. In in vitro experiments, hepatocytes and KCs were separately isolated from rat livers. The incubation medium for KCs treated with LPS (KC-CM) was used for hepatocyte culture.

RESULTS

  Intravenous injections of LPS enhanced the expression of naofen in the livers. Livers showed terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive staining, and elevated caspase-3 activity. In isolated KCs or hepatocytes, LPS hardly affected naofen expression and caspase-3 activity, whereas incubation of hepatocytes with KC-CM enhanced both naofen expression and caspase-3 activation. Transfection of hepatocyte with naofen siRNA prevented such effects of KC-CM, and clearly eliminated KC-CM-induced reduction of Bcl-2 and Bcl-xL. In contrast, overexpression of naofen in hepatocytes downregulated Bcl-2 and Bcl-xL, released cytochrome c from mitochondria, and activated caspase-3.

CONCLUSION

  These results indicate that LPS may induce the hepatic apoptosis in association with enhanced naofen expression, and that naofen may mediate the activation of caspase-3 through downregulating the Bcl-2 and Bcl-xL expression, and releasing cytochrome c from mitochondria to cytoplasm.

Alcohol Consumption, Progression of Disease and Other Comorbidities, and Responses to Antiretroviral Medication in People Living with HIV

The present paper describes the possible connection between alcohol consumption and adherence to medicine used to treat human deficiency viral (HIV) infection. Highly active antiretroviral therapy (HAART) has a positive influence on longevity in patients with HIV, substantially reducing morbidity and mortality, including resource-poor settings such as South Africa. However, in a systematic comparison of HAART outcomes between low-income and high-income countries in the treatment of HIV-patients, mortality was higher in resource-poor settings. Specifically, in South Africa, patients often suffer from concomitant tuberculosis and other infections that may contribute to these results. Alcohol influences the use of medicine for opportunistic infections (e.g., pneumonia, tuberculosis), or coinfections HIV-hepatitis viruses-B (HBV) and C (HCV), cytomegalovirus, or herpes simplex virus. Furthermore, alcohol use may negatively impact on medication adherence contributing to HIV progression. The materials used provide a data-supported approach. They are based on analysis of published (2006–2011) world literature and the experience of the authors in the specified topic. Intended for use by health care professionals, these recommendations suggest approaches to the therapeutic and preventive aspects of care. Our intention was to fully characterize the quality of evidence supporting recommendations, which are reflecting benefit versus risk, and assessing strength or certainty.

Markers of inflammation and fibrosis in alcoholic hepatitis and viral hepatitis C

High levels of profibrinogenic cytokine transforming factor beta (TGF-β), metalloprotease (MMP2), and tissue inhibitor of matrix metalloprotease 1 (TIMP1) contribute to fibrogenesis in hepatitis C virus (HCV) infection and in alcohol-induced liver disease (ALD). The aim of our study was to correlate noninvasive serum markers in ALD and HCV patients with various degrees of inflammation and fibrosis in their biopsies. Methods. Serum cytokines levels in HCV-infected individuals in the presence or absence of ALD were measured. Student's-t-test with Bonferroni correction determined the significance between the groups. Results. Both tumor-necrosis-factor- (TNF)-α and TGF-β levels increased significantly with the severity of inflammation and fibrosis. TGF-β levels increased significantly in ALD patients versus the HCV patients. Proinflammatory cytokines' responses to viral and/or toxic injury differed with the severity of liver inflammation. A combination of these markers was useful in predicting and diagnosing the stages of inflammation and fibrosis in HCV and ALD. Conclusion. Therapeutic monitoring of TGF-β and metalloproteases provides important insights into fibrosis.

Cultivating hepatocytes on printed arrays of HGF and BMP7 to characterize protective effects of these growth factors during in vitro alcohol injury

The goal of the present study was to investigate hepato-protective effects of growth factor (GF) arrays during alcohol injury. Hepatocyte growth factor (HGF) and bone morphogenetic protein (BMP)7 were mixed with collagen (I) and robotically printed onto standard glass slides to create arrays of 500 microm diameter spots. Primary rat hepatocytes were seeded on top of the arrays forming clusters corresponding in size to the underlying protein spots. Cell arrays were then injured in culture by exposure to 100 mm ethanol for 48 h. Hepatocytes residing on GF spots were found to have less apoptosis then cells cultured on collagen-only spots. Least apoptosis (0.3% as estimated by TUNEL assay) was observed on HGF/BMP7/collagen spots whereas most apoptosis (17.3%) was seen on collagen-only arrays. Interestingly, the extent of alcohol-induced apoptosis in hepatocytes varied based on the concentration of printed GF. In addition to preventing apoptosis, printed GFs contributed to maintenance of epithelial phenotype during alcohol injury as evidenced by higher levels of E-cadherin expression in HGF-protected hepatocytes. Importantly, GF microarrays could be used to investigate heterotypic interactions in the context of liver injury. To highlight this, stellate cells - nonparenchymal liver cells involved in fibrosis - were added to hepatocytes residing on arrays of either HGF/collagen or collagen-only spots. Exposure of these cocultures to ethanol followed by RT-PCR analysis revealed that stellate cells residing alongside HGF-protected hepatocytes were significantly less activated (less fibrotic) compared to controls. Overall, our results demonstrate that GF microarray format can be used to screen anti-fibrotic and anti-apoptotic effects of growth factors as well as to investigate how signals delivered to a specific cell type modulate heterotypic cellular interactions.

Dual effect of erythropoietin on liver protection and regeneration after subtotal hepatectomy in rats

The only currently offered curative option for many patients with primary or secondary liver tumors is the resection of hepatic tumors. The aim of this study was to evaluate the role of recombinant human erythropoietin (rhEPO) in liver protection and regeneration after subtotal hepatectomy in rats. Rats undergoing 70% hepatectomy received an intraperitoneal injection of saline (control) or rhEPO (4 U/g) 30 minutes prior to resection. Liver function was assessed by the measurement of the international normalized ratio (INR) levels, and hepatic injury was assessed by serum alanine aminotransferase and aspartate aminotransferase levels. Hepatic apoptosis was assessed by intrahepatic caspase-3 activity and morphological criteria. The regeneration capacity of remnant livers was assessed over 7 days with the regenerated liver/body weight ratio, immunohistochemistry markers of cell proliferation (Ki-67) and angiogenesis (von Willebrand factor), and phosphorylated extracellular signal-regulated kinase signaling. Two and 4 days after subtotal hepatectomy, the regenerated liver/body weight ratio was significantly higher in animals treated with rhEPO versus the control group (P < 0.005). Serum liver enzymes and INR levels on days 2 and 4 post-hepatectomy were significantly lower in animals pretreated with rhEPO in comparison with the control group (P < 0.005). No statistically significant difference was noted in intrahepatic hepatic caspase-3 activity, immunohistochemistry for caspase-3, or a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay between the hepatectomized groups. In the rhEPO-pretreated group, the mitotic index, Ki-67 and von Willebrand factor expression, and extracellular signal-regulated kinase activity were significantly higher on day 2 post-hepatectomy (P < 0.05) in comparison with the control group. In conclusion, rhEPO treatment may offer a unique beneficial dual-function strategy for hepatic protection and regeneration immediately after subtotal hepatectomy in rats.

Chronic alcohol consumption is associated with an increased cytotoxic profile of circulating lymphocytes that may be related with the development of liver injury

BACKGROUND

Apoptosis has recently emerged as a key component of acute and chronic liver diseases and it could be related to alcoholic liver disease. In the present study, we attempted to analyze the cytotoxic profile of circulating lymphocytes in chronic alcoholic patients grouped according to ethanol intake status and presence of liver disease.

METHODS

We investigate the phenotypic and functional behavior of different compartments of peripheral blood (PB) cytotoxic T and natural killer (NK) cells in chronic alcoholic patients without liver disease and active ethanol intake (AWLD group; n = 22), and in subjects with alcohol liver cirrhosis (ALC group; n = 22).

RESULTS

AWLD patients showed an expansion of both CD4+/CD8+ cytotoxic T cells and NK/T cells, in association with an enhanced cytolytic activity against K562 cells and a higher ability to induce in vitro expression of the pro-apoptotic protein APO2.7 in HepG2 cells. Conversely, ethanol intake in ALC patients was associated with decreased NK cell numbers, a reduced cytotoxic activity against K562 cells without significant changes in the expression of APO2.7, and a pro-fibrotic profile of cytokine secretion.

CONCLUSIONS

Overall, our results suggest that alcoholic patients display different phenotypical and functional changes in circulating PB cytotoxic lymphocytes according to the presence of alcoholic liver disease, which could be related to the development and progress of liver injury.

Hepatocyte growth factor protects against Fas-mediated liver apoptosis in transgenic mice

BACKGROUND

Apoptosis via the Fas/Fas ligand signalling system plays an important role in the development of various liver diseases. The administration of an agonistic anti-Fas antibody to mice causes massive hepatic apoptosis and fulminant hepatic failure. Several growth factors including hepatocyte growth factor (HGF) have been found to prevent apoptosis.

METHODS

In this study, we demonstrated the overexpression of HGF to have a protective effect on Fas-mediated hepatic apoptosis using a transgenic mice (Tg mice) model.

RESULTS

In HGF Tg mice, the elevation of alanine aminotransferase was dramatically inhibited at 12 and 24 h after the administration of 0.15 mg/kg anti-Fas antibody. HGF Tg mice showed a significantly lower number of apoptotic hepatocytes at 12 h compared with wild-type (WT) mice. Furthermore, 85% (six of seven) HGF Tg mice were able to survive after the administration of 0.3 mg/kg anti-Fas antibody, while none of the WT mice survived. The Bcl-xL expression was increased in HGF Tg mice, while there was no difference in the expression of Bax, Bid, Mcl-1 and bcl-2 between WT mice and HGF Tg mice. In addition, the HGF Tg mice showed more Akt phosphorylation than the WT mice both before and after the anti-Fas antibody injection.

CONCLUSIONS

Taken together, our findings suggest that HGF protects against Fas-mediated liver apoptosis in vivo, and the upregulation of Bcl-xL via Akt activation may also play a role in the protective effects of HGF.

Molecular Biology of Apoptosis in Ischemia and Reperfusion

This study reviews the current understanding of the mechanisms that mediate the complex processes involved in apoptosis secondary to ischemia and reperfusion (I/R) and is not intended as a complete literature review of apoptosis. Several biochemical reactions trigger a cascade of events, which activate caspases. These caspases exert their effect through downstream proteolysis until the final effector caspases mediate the nuclear features characteristic of apoptosis, DNA fragmentation and condensation. Within the context of ischemia, the hypoxic environment initiates the expression of several genes involved in inflammation, the immune response, and apoptosis. Many of these same genes are activated during reperfusion injury in response to radical oxygen species generation. It is plausible that inhibition of specific apoptotic pathways via inactivation or downregulation of those genes responsible for the initiation of inflammation, immune response, and apoptosis may provide promising molecular targets for ameliorating reperfusion injury in I/R-related processes. Such inhibitory mechanisms are discussed in this review. Important targets in I/R-related pathologies include the brain during stroke, the heart during myocardial infarction, and the organs during harvesting and/or storage for transplantation. In addition, we present data from our ongoing research of specific signal transduction-related elements and their role in ischemia/reperfusion injury. These data address the potential therapeutic application of anti-inflammatory and anti-ischemic compounds in the prevention of I/R damage.

Neutralization of IL-10 Exacerbates Cycloheximide-Induced Hepatocellular Apoptosis and Necrosis

Cycloheximide (CHX)-induced liver injury in rats has been characterized by hepatocellular apoptosis and necrosis. We previously reported that Kupffer cell inactivation causes a reduction of IL-10 production, resulting in the exacerbation of CHX-induced liver injury. In this study, we directly evaluate the role of IL-10 in liver injury by a pretreatment with anti-IL-10 neutralizing antibody (IL-10Ab). Rats were given goat IgG or IL-10Ab before being treated with CHX (CHX group or IL-10Ab/CHX group). In the CHX group, the CHX treatment markedly induced hepatic mRNA and serum protein levels of IL-10. The up-regulation of IL-10 was significantly suppressed in the IL-10Ab/CHX group. Blocking IL-10 in the IL-10Ab/ CHX group led to greater increases in hepatic mRNA and serum levels of proinflammatory cytokines, such as TNF-α and IL-6. The IL-10Ab/CHX group developed more severe hepatocellular apoptosis, neutrophil transmigration, and necrotic change of hepatocytes compared with the CHX group. The caspase activities and mRNA levels of Cc120, LOX-1, and E-selectin in the livers were significantly higher in the IL-10Ab/CHX group than the CHX group. These results demonstrate that IL-10 plays an important role in counteracting the effect of proinflammatory cytokines, such as a TNF signaling cascade, and in attenuating the CHX-induced liver injury.

Increased apoptosis in HepG2.2.15 cells with hepatitis B virus expression by synergistic induction of interferon-gamma and tumour necrosis factor-alpha

BACKGROUND

Interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were thought to be important immune mediators in host defence against hepatitis B virus (HBV) infection.

AIMS

To examine the synergistic effect of IFN-gamma and TNF-alpha on HBV-expressing HepG2.2.15 cells and its potential mechanisms.

METHODS

Cell viability was quantitatively measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. Cell morphology was captured using light microscopy. The typical DNA ladder test was performed using agarose gel electrophoresis. HBsAg and HBeAg titre changes were quantified by the enzyme-linked immunosorbent assay method. Gene expression was analysed using cDNA macroarrays.

RESULTS

Interferon-gamma (1000 U/ml) alone or combined with TNF-alpha (5 ng/ml) treatment resulted in apoptosis in HepG2.2.15 cells, but no significant apoptosis in the parent non-virus expressing HepG2 cells. IFN-gamma- and TNF-alpha-mediated apoptosis was reduced by lamivudine treatment in HepG2.2.15 cells. IFN-gamma combined with TNF-alpha reduced the titre of hepatitis B surface antigen and hepatitis B e antigen in the HepG2.2.15 cell line. For apoptosis-related gene changes, IFN regulatory factor 1 (IRF-1) (12.2-fold), c-myc (V00568 4.7-fold, L00058 2.4-fold) and caspase 7 (2.3-fold) genes were upregulated in the combination treatment group.

CONCLUSION

Interferon-gamma and TNF-alpha play a role in the cell death of HBV-expressing HepG2.2.15 cells. Expression of HBV leads to IFN-gamma- and TNF-alpha-mediated apoptosis in the cells. Increased IRF-1, c-myc and caspase 7 gene expression may be responsible for the synergistic induction of apoptosis by IFN-gamma and TNF-alpha.

Inflammatory pathways in liver homeostasis and liver injury

The liver is a unique organ with respect to its anatomical location, allowing continuous blood flow from the gastrointestinal tract through the sinusoids, and its cellular composition, comprising metabolically active hepatocytes, nonhepatocytic parenchymal cells, and various immune cell populations. Cytokines are key mediators within the complex interplay of intrahepatic immune cells and hepatocytes, as they can activate effector functions of immune cells, as well as hepatocytic intracellular signaling pathways controlling cellular homeostasis. Kupffer cells and liver-infiltrating monocyte-derived macrophages are primary sources of cytokines such as tumor-necrosis factor-alpha (TNF-alpha) and interleukin-6. The liver is also enriched in natural killer (NK) and NK T cells, which fulfill functions in pathogen defense, T cell recruitment, and modulation of liver injury. TNF-alpha can activate specific intracellular pathways in hepatocytes that influence cell fate in different manners, e.g., proapoptotic signals via the caspase cascade, but also survival pathways, namely the nuclear factor (NF)-kappaB pathway. NF-kappaB regulates important functions in liver physiology and pathology. Recent experiments with genetically modified mice demonstrated important and partly controversial functions of this pathway, e.g., in cytokine-mediated hepatocyte apoptosis or ischemia-reperfusion injury. The exact dissection of the contribution of recruited and resident immune cells, their soluble cytokine and chemokine mediators, and the intracellular hepatocytic response in liver homeostasis and injury could potentially identify novel targets for the treatment of acute and chronic liver disease, liver fibrosis, or cirrhosis.

Effect of porto-systemic shunting on NOS expression after extended hepatectomy in rats

AIM

Several surgical procedures have been developed for reducing portal vein pressure to prevent postoperative liver injury. Nitric oxide synthase expression (NOS) induced by elevation of portal vein pressure is thought to play an important role in liver regeneration, but the details are not well understood.

METHODS

Rats in the control group and in the subcutaneous splenic transposition (SST) group underwent 90% partial hepatectomy. Survival and portal vein pressure were analyzed. The serum IL-6 and TNF-alpha levels were measured by enzyme-linked immunosorbent assay (ELISA). Hepatocyte proliferation and apoptosis 12 hours after hepatectomy were analyzed immunohistochemically. The protein and messenger RNA expression of inducible and endothelial NOS were analyzed using Western blotting and quantitative reverse transcriptase polymerase chain reaction, respectively.

RESULTS

The survival rate of the SST group was significantly higher. Portal vein pressure, TNF-alpha level and the apoptotic index were significantly lower in the SST group. Twelve hours after surgery, liver inducible NOS (iNOS) protein expression was significantly lower in the SST group. However, protein expression of endothelial NOS was not significantly different between the groups.

CONCLUSION

Inducible NOS expression after extended hepatectomy is related to the effects of porto-systemic shunting on the splanchnic circulation. Also, iNOS induction and concomitant nitric oxide generation appear to participate in the cytotoxicity of excessive portal pressure after extended hepatectomy.

Green-tea polyphenols downregulate cyclooxygenase and Bcl-2 activity in acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) elicits hepatotoxicity via multifactorial pathways, including increased apoptosis, cyclooxygenase (Cox-2) generation, reactive metabolite release, and glutathione (GSH) depletion. We previously showed that mice that consumed different antioxidants in their diets were protected against APAP-induced hepatotoxicity. We therefore further investigated the mechanisms by which green-tea polyphenols (GrTP) protect against APAP-induced hepatic damage. Mice were administered a diet supplemented with GrTP or vehicle for 5 consecutive days followed by intraperitoneal (IP) injection of a toxic dose of APAP or sham. APAP administration upregulated Cox-2 and B-cell lymphoma-2 (Bcl-2) production and had an effect, albeit minor, on Cox-1 and Fas expression in hepatic tissue. GrTP supplementation normalized APAP induced Cox-2 expression and Bcl-2 activation (P < 0.01), as evidenced by immunohistochemistry and Western blot analyses. Similarly, APAP administration elicited marked depletion (99%) in hepatic reduced GSH (rGSH) and endogenous S-adenosylmethionine (SAMe) concentrations (twofold) when compared with sham. APAP also caused severe centrilobular apoptosis and necrosis accompanied by leukocyte infiltration and marked elevations in the hepatic enzyme, alanine aminotransferase (ALT) released from damaged hepatocytes, and cytokine tumor necrosis factor alpha (TNF-alpha). GrTP improved hepatic histopathology (P < 0.01) and attenuated ALT activity (P < 0.05) and the depletion of rGSH (P < 0.05). In conclusion, GrTP supplementation attenuated hepatotoxicity by normalizing Cox-2 and Bcl-2 activation, suggesting a potential use for GrTP in treatng APAP toxicity.

TNF pretreatment interferes with mitochondrial apoptosis in the mouse liver by A20-mediated down-regulation of Bax

Pretreatment with low doses of the proinflammatory cytokine TNF has been shown to prevent hepatocellular apoptosis and liver damage in inflammatory as well as in ischemia/reperfusion-induced liver injury. The underlying mechanisms of protection have not been elucidated so far. In this study, these mechanisms were investigated in murine hepatocyte cultures as well as in a mouse model of TNF-dependent apoptotic liver damage (galactosamine/TNF model). Our results show that pretreatment with TNF, or application of small-interfering RNA directed against the proapoptotic Bcl2 family member Bax, interfered with the onset of mitochondrial apoptosis in vivo. Knockdown of TNF-alpha-induced-protein 3 (A20) restored mitochondrial apoptosis, Bax expression, and liver damage. The underlying mechanism of protection seems to involve a cascade of events, where TNF induces the expression of A20 in hepatocytes, A20 down-modulates Bax expression by interference with transcriptional activation, and the reduced availability of Bax interferes with the onset of mitochondrial apoptosis and the ensuing apoptotic liver damage. In conclusion, we identified Bax and A20 as key players in TNF-induced protection from apoptotic liver damage. Because treatment with TNF itself might be a risk factor for patients, we propose that overexpression of A20 might represent an alternative approach for protection from inflammation related apoptotic liver damage, as well as for TNF preconditioning during transplantation.

Senecio latifolius induces in vitro hepatocytotoxicity in a human cell lineThis article is one of a selection of papers published in this special issue (part 2 of 2) on the Safety and Efficacy of Natural Health Products

The objectives of this study were twofold: (i) to determine the mechanism(s) of Senecio -induced toxicity in human hepatoblastoma cells (HepG2) in vitro and whether such toxicity could be prevented using N-acetyl-cysteine (NAC), and (ii) to evaluate whether caspases are involved in Senecio-induced apoptosis. Cells were treated with aqueous extracts of Senecio (10 mg·mL–1) with and without NAC. Cytotoxicity was determined by using the MTT assay. Total glutathione (GSH) was measured by using the Tietze assay. Cells were also treated with aqueous extracts of Senecio in the presence or absence of 50 μmol/L caspase-3 inhibitor (IDN) for 24 h. Apoptosis was determined by transmission electron microscopy, and DNA fragmentation was determined by ELISA and terminal dUTP nick-end labelling (TUNEL). Senecio produced cytotoxicity and depleted GSH in a concentration- and time-dependent manner. A significant depletion in GSH was observed after 15 min (p < 0.001 vs. control), whereas significant cytotoxicity was only observed after 3 h (p < 0.001 vs. control). Treatment with NAC prevented Senecio-induced GSH depletion and resulted in a significant decrease in Senecio-induced cytotoxicity (p < 0.001 vs. NAC-untreated cells). Treatment with Senecio for 24 h resulted in 22% ± 2.5% (p < 0.001) apoptosis (vs. control). Pretreatment with 50 μmol caspase inhibitor reduced Senecio-induced apoptosis significantly (vs. non-exposed to IDN) (12% ± 1.5%; p < 0.05). Our results suggest the mechanism of Senecio-induced cytotoxicity in HepG2 cells in vitro involves depletion of cellular GSH. Cytotoxicity is reduced by supplementation with NAC, which thus prevents GSH depletion. Caspase activation is involved in Senecio-induced apoptosis.

Changes in the expression of genes related to apoptosis and fibrosis pathways in CCl4-treated rats

Chronic liver diseases are accompanied by changes in the biochemical pathways related to the regulation of apoptosis and extra-cellular matrix deposition. The present study was designed to investigate, using low density arrays, changes in the hepatic gene expression together with hepatic biochemical and histological alterations in rats that had liver impairment induced by chronic exposure to CCl(4). Further, we examined the possible recovery of genetic and pathological changes following the cessation of the hepatotoxic injury. Experimental fibrosis was induced in male Wistar rats by CCl(4) administration. Animals were subdivided into two groups. One group was given CCl(4 )and animals were killed at 8 and 12 weeks of treatment. The other group was treated with CCl(4) for 6 weeks, the CCl(4 )was then stopped and, subsequently, subgroups of animals were killed after 1 and 2 weeks of recovery. CCl(4) administration over 12 weeks was associated with significant changes in B-cell leukemia/lymphoma 2, procollagen type I alpha 2, matrix metalloproteinases 3 and 8, tissue inhibitors of metalloproteinases 1, 2, and 3 and the inhibitor of apoptosis 4 gene expressions. Recovery after CCl(4) cessation was associated with changes in procollagen type I alpha 2, matrix metalloproteinase 7, tissue inhibitors of metalloproteinases 1 and 2, inhibitor of apoptosis 4, and survivin gene expressions. This study shows an association between changes in the expression of several genes regulating hepatic cell apoptosis, the fibrosis process, and the recovery of the hepatic function after removal of the toxic injury.