Apoptosis and liver disease

Microcystin-LR and polystyrene microplastics jointly lead to hepatic histopathological damage and antioxidant dysfunction in male zebrafish

The co-occurrence of cyanobacterial blooms and nano-microplastic pollution in the water is becoming an emerging risk. To assess the combined hepatotoxicity of microcystin-LR (MC-LR) and polystyrene microplastics (PSMPs) on zebrafish (Danio rerio), male adult zebrafish were exposed to single MC-LR (0, 1, 5, 25 μg/L) and a mixture of MC-LR and PSMPs (100 μg/L). After 60 d exposure, the results indicated that PSMPs significantly increased the MC-LR bioaccumulation in the livers in contrast to the single 25 μg/L MC-LR treatment group. Moreover, the severity of hepatic pathological lesions was aggravated in the MC-LR + PSMPs treatment groups, which were mainly characterized by cellular vacuolar degeneration, swollen hepatocytes, and pyknotic nucleus. The ultrastructural changes also proved that PSMPs combined with MC-LR could enhance the swollen mitochondria and dilated endoplasmic reticulum. The biochemical results, including increased malondialdehyde (MDA) and decreased glutathione (GSH), indicated that PSMPs intensified the MC-LR-induced oxidative damage in the combined treatment groups. Concurrently, alterations of sod1 and keap1a mRNA levels also confirmed that PSMPs together with MC-LR jointly lead to enhanced oxidative injury. Our findings demonstrated that PSMPs enhanced the MC-LR bioavailability by acting as a vector and exacerbating the hepatic injuries and antioxidant dysfunction in zebrafish.

Salidroside in the Treatment of NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD) is the commonest reason for chronic liver diseases in the world and is commonly related to the hepatic manifestation of the metabolic syndrome. Non-alcoholic steatohepatitis (NASH) is a deteriorating form of NAFLD, which can eventually develop into fibrosis, cirrhosis, and liver cancer. The reason for NAFLD/NASH development is complicated, such as liver lipid metabolism, oxidative stress, inflammatory response, apoptosis and autophagy, liver fibrosis and gut microbiota. Apart from bariatric surgery and lifestyle changes, officially approved drug therapy for NAFLD/NASH treatment is lacking. Salidroside (SDS) is a phenolic compound extensively distributed in the tubers of Rhodiola plants, which possesses many significant biological activities. This review summarized the related targets regulated by SDS in treating NAFLD/NASH. It is indicated that SDS could improve the status of NAFLD/NASH by ameliorating abnormal lipid metabolism, inhibiting oxidative stress, regulating apoptosis and autophagy, reducing inflammatory response, alleviating fibrosis and regulating gut microbiota. In conclusion, although the multiple bioactivities of SDS have been confirmed, the clinical data are inadequate and need to become the focus of attention in the later study.

Microarray gene expression profiling provides insights into functions of TIPE2 in HBV-related apoptosis

Tumor necrosis factor-α-induced protein-8 like-2 (TNFAIP8L2, TIPE2), a member of TNFAIP8 family, functions as a regulator in inflammation. Our previous studies showed that TIPE2 can negatively regulate HBV-specific CD8⁺ T lymphocyte functions. But the effect of TIPE2 on the apoptosis of HBV-infected hepatocytes which is very important for eliminating viruses remains unclear. Using gene expression microarray analysis, we find that TIPE2 deficiency can regulate the expression of apoptotic genes in liver tissues from HBV hydrodynamic injection (HI) mouse model. TIPE2 protein was detected in TUNEL staining positive hepatocytes in HBV-infected C57 mice. Interestingly, the TIPE2 expressed hepatocytes were just the HBV infected cells. Furthermore, TIPE2 upregulates the mRNA levels of FasL, Bim and TNFRsF1b which promote cells death, when TIPE2 was transfected into HepG2 cells in vitro. As a result, TIPE2 overexpression cells showed a higher number of apoptotic cells and increased level of cleavage caspase3 compared to controls. Those results indicate that TIPE2 participates in HBV infection by regulating apoptosis of virus-infected hepatocytes.

M1 and M2 Macrophages Polarization via mTORC1 Influences Innate Immunity and Outcome of Ehrlichia Infection

Human monocytic ehrlichiosis (HME) is an emerging life-threatening tick-borne disease caused by the obligate intracellular bacterium Ehrlichia chaffeensis. HME is often presented as a nonspecific flu-like illness characterized by presence of fever, headache, malaise, and myalgia. However, in some cases the disease can evolve to a severe form, which is commonly marked by acute liver injury followed by multi-organ failure and toxic shock-like syndrome [1-3]. Macrophages and monocytes are the major target cells for Ehrlichia, although this bacterium can infect other cell types such as hepatocytes and endothelial cells [4]. In this article, we discuss how macrophages polarization to M1 or M2 phenotypes dictate the severity of ehrlichiosis and the outcome of infection. We will also discuss the potential mechanisms that regulate such polarization.

mTORC1-mediated polarization of M1 macrophages and their accumulation in the liver correlate with immunopathology in fatal ehrlichiosis

A polarized macrophage response into inflammatory (M1) or regenerative/anti-inflammatory (M2) phenotypes is critical in host response to multiple intracellular bacterial infections. Ehrlichia is an obligate Gram-negative intracellular bacterium that causes human monocytic ehrlichiosis (HME): a febrile illness that may progress to fatal sepsis with multi-organ failure. We have shown that liver injury and Ehrlichia-induced sepsis occur due to dysregulated inflammation. Here, we investigated the contribution of macrophages to Ehrlichia-induced sepsis using murine models of mild and fatal ehrlichiosis. Lethally-infected mice showed accumulation of M1 macrophages (iNOS-positive) in the liver. In contrast, non-lethally infected mice showed polarization of M2 macrophages and their accumulation in peritoneum, but not in the liver. Predominance of M1 macrophages in lethally-infected mice was associated with expansion of IL-17-producing T, NK, and NKT cells. Consistent with the in vivo data, infection of bone marrow-derived macrophages (BMM) with lethal Ehrlichia polarized M0 macrophages into M1 phenotype under an mTORC1-dependent manner, while infection with non-lethal Ehrlichia polarized these cells into M2 types. This work highlights that mTORC1-mediated polarization of macrophages towards M1 phenotype may contribute to induction of pathogenic immune responses during fatal ehrlichiosis. Targeting mTORC1 pathway may provide a novel aproach for treatment of HME.

A systems pharmacology-oriented discovery of a new therapeutic use of the TCM formula Liuweiwuling for liver failure

Multiple components of traditional Chinese medicine (TCM) formulae determine their treatment targets for multiple diseases as opposed to a particular disease. However, discovering the unexplored therapeutic potential of a TCM formula remains challenging and costly. Inspired by the drug repositioning methodology, we propose an integrated strategy to feasibly identify new therapeutic uses for a formula composed of six herbs, Liuweiwuling. First, we developed a comprehensive systems approach to enrich drug compound-liver disease networks to analyse the major predicted diseases of Liuweiwuling and discover its potential effect on liver failure. The underlying mechanisms were subsequently predicted to mainly attribute to a blockade of hepatocyte apoptosis via a synergistic combination of multiple effects. Next, a classical pharmacology experiment was designed to validate the effects of Liuweiwuling on different models of fulminant liver failure induced by D-galactosamine/lipopolysaccharide (GalN/LPS) or thioacetamide (TAA). The results indicated that pretreatment with Liuweiwuling restored liver function and reduced lethality induced by GalN/LPS or TAA in a dose-dependent manner, which was partially attributable to the abrogation of hepatocyte apoptosis by multiple synergistic effects. In summary, the integrated strategy discussed in this paper may provide a new approach for the more efficient discovery of new therapeutic uses for TCM formulae.

Fluoride-associated ultrastructural changes and apoptosis in human renal tubule: a pilot study

The susceptibility of the kidneys to fluoride toxicity can largely be attributed to its anatomy and function. As the filtrate moves along the complex tubular structure of each nephron, it is concentrated in the proximal and distal tubules and collecting duct. It has been frequently observed that the children suffering from renal impairments also have some symptoms of dental and skeletal fluorosis. The findings suggest that fluoride somehow interferes with renal anatomy and physiology, which may lead to renal pathogenesis. The aim of this study was to evaluate the fluoride-associated nephrotoxicity. A total of 156 patients with childhood nephrotic syndrome were screened and it was observed that 32 of them had significantly high levels ( p ≤ 0.05) of fluoride in urine (4.01 ± 1.83 ppm) and serum (0.1 ± 0.013 ppm). On the basis of urinary fluoride concentration, patients were divided into two groups, namely group 1 (G-1) ( n = 32) containing normal urine fluoride (0.61 ± 0.17 ppm) and group 2 (G-2) ( n = 32) having high urine fluoride concentration (4.01 ± 1.83 ppm). Age-matched healthy subjects ( n = 33) having normal levels of urinary fluoride (0.56 ± 0.15 ppm) were included in the study as control (group 0 (G-0)). Kidney biopsies were taken from G-1 and G-2 only, who were subjected to ultrastructural (transmission electron microscopy) and apoptotic (terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling) analysis. Various subcellular ultrastructural changes including nuclear disintegration, chromosome condensation, cytoplasmic ground substance lysis, and endoplasmic reticulum blebbing were observed. Increased levels of apoptosis were observed in high fluoride group (G-2) compared to normal fluoride group (G-1). Various degrees of fluoride-associated damages to the architecture of tubular epithelia, such as cell swelling and lysis, cytoplasmic vacuolation, nuclear condensation, apoptosis, and necrosis, were observed.

P38 MAP kinase is involved in oleuropein-induced apoptosis in A549 cells by a mitochondrial apoptotic cascade

Lung cancer is one of malignant tumors that cause great threats to human health, which causes the fastest growing morbidity and mortality. Oleuropein as natural production exerts anticancer effects in several cancer cells. In the study, we investigated apoptotic effect of oleuropein on A549 cells and the underlying mechanisms. Oleuropein markedly decreased cell viability in A549 cells by resulting in G₂/M phase arrest, but failed to decreased cell viability in BEAS-2B cells significantly. Apoptosis by oleuropein was confirmed by apoptotic morphology, accumulation in a sub-G₁ peak, nucleus fragmentation and cleavage of PARP. Dose-dependent elevation in p-p38MAPK and p-ATF-2 was observed whereas apparent changes could not be observed in p-JNK and p-c-Jun, showing activation of p38MAPK but not JNK. Interestingly, ERK1/2 appeared to be constant while p-ERK1/2 was reduced dose-dependently. Oleuropein caused decrease in mitochondrial membrane potential, increase in Bax/Bcl- 2 ratio, release of mitochondrial cytochrome c and activation of caspase-9 and caspase-3, implying that mitochondrial apoptotic pathway was activated. Additionally, oleuropein-induced apoptosis was dramatically attenuated by Z-VAD-FMK (caspase inhibitor). The p38MAPK inhibitor prevented production of apoptotic bodies and reduced expressions of cleaved-PARP, p-P38, p-ATF-2 and release of cytochrome c. Taken together, these results demonstrated p38MAPK signaling pathway mediated oleuropein-induced apoptosis via mitochondrial apoptotic cascade in A549 cells. Oleuropein has the potential to be a therapeutic drug for lung cancer treatment.

Effect of tanshinone IIA on oxidative stress and apoptosis in a rat model of fatty liver

Oxidative stress is a crucial factor associated with fatty liver disease, which raises the possibility of using antioxidants to improve liver steatosis. Tanshinone IIA (TSIIA) is a traditional Chinese medicine that has been reported to have antioxidant effects in vitro. The present study aimed to investigate whether TSIIA possesses antioxidant effects in vivo and whether TSIIA was able to improve liver steatosis. Hence, the ability of TSIIA to protect rats from liver disease was explored, particularly in regard to antioxidant activity. Rats were fed a high-lipid diet for 90 days, causing severe liver steatosis, both morphologically and biochemically. An increase in reactive oxygen species (ROS) in the liver was exhibited in addition to significantly elevated serum lipids and malondialdehyde (MDA). Furthermore, hepatocyte apoptosis was measured by Hoechst staining, reverse transcription-quantitative polymerase chain reaction and western blot analysis and an increase in hepatocyte apoptosis rate was indicated in mice on a high-fat diet. Following intraperitoneal injection of TSIIA (10 mg/kg/day), liver steatosis was significantly inhibited. In rats receiving TSIIA treatment, less ROS were indicated in the liver and significantly decreased levels of MDA (P<0.05) in serum were exhibited, whereas significantly increased activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) were observed (P<0.05 and P<0.01, respectively). In addition, the rate of hepatocyte apoptosis was significantly decreased in the TSIIA group (P<0.01). However, TSIIA elicited no effect on serum lipid profiles. These results suggest that TSIIA attenuates oxidative stress by decreasing ROS and MDA production and enhancing the activity of T-SOD and GSH-PX, which may contribute to the inhibition of apoptosis and amelioration of liver steatosis.

Serum Levels of Oxidative Stress Markers in Patients with Type 2 Diabetes Mellitus and Non-alcoholic Steatohepatitis

INTRODUCTION

Oxidative stress is one of the key mechanisms responsible for disease progression in non-alcoholic fatty liver disease. The aim of this study was to evaluate the serum levels of oxidative stress markers in patients with type 2 diabetes mellitus (DMT2) and non-alcoholic steatohepatitis (NASH) and test their relationships with clinical and biochemical patient characteristics, compared to patients with DMT2 without non-alcoholic fatty liver disease (NAFLD), and controls.

MATERIALS AND METHODS

In all, 60 consecutive patients with DMT2 and NASH, 55 with DMT2 without NAFLD, and 50 age-and-gender-matched healthy subjects participated in the study. The serum levels of protein carbonyls and 8-isoprostane were determined by ELISA methods, while the serum levels of malondialdehyde (MDA) were detected by means of the spectrophotometric method. Clinical, demographic, and laboratory parameters were examined for all the subjects included in the study. Multivariate logistic regression was used to test the independent predictive factors in the relationships investigated here.

RESULTS

Patients with DMT2 and NASH displayed significantly higher serum levels of protein carbonyls (1.112 ± 0.42 nmol/dL), MDA (6.181 ± 1.81 ng/mL), and 8-isoprostane (338.6 ± 98.5 pg/mL) compared to patients with DMT2 without NAFLD, and controls. Results of multivariate logistic regression analyses indicate that in patients with DMT2 and NASH, the serum levels of oxidative stress markers were independently and positively associated with: HbA1c, duration of diabetes, the UKPDS cardiovascular risk score (for protein carbonyls); age, LDL-cholesterol (for 8-isoprostane); and triglycerides serum levels (for MDA).

CONCLUSIONS

Our findings indicate that the process of oxidative stress tends to increase in patients with DMT2 and NASH, compared to patients with DMT2 without NAFLD, and controls. This evidence suggests that an antioxidant therapy might prove useful in the treatment of patients with DMT2 and NASH.

Diet high in fructose promotes liver steatosis and hepatocyte apoptosis in C57BL/6J female mice: Role of disturbed lipid homeostasis and increased oxidative stress

The effects of high (H)-fructose (FR) diet (D) (HFRD) on hepatic lipid homeostasis, oxidative stress, inflammation and hepatocyte apoptosis were investigated in 6-week old female C57BL/6J mice fed a regular chow (ContD) or HFRD (35% fructose-derived calories) for 3 weeks. HFRD-fed mice exhibited increased levels of hepatic steatosis with a significant elevation of serum levels of triglyceride, cholesterol and TNFα compared to ContD-fed mice (P<0.05). HFRD-fed mice exhibited ∼2.7- fold higher levels FAS along with significantly decreased protein levels of adiponection-R2 (∼30%), P-AMPK (∼60%), P-ACC (∼70%) and RXR-α (∼55%), suggesting decreased hepatic fat oxidation compared to controls. Interestingly, hepatic fatty acid uptake into hepatocytes and lipolysis were significantly increased in HFRD-fed mice, as shown by decreased CD36 and fatty acid transporter protein-2, and increased adipose triglyceride lipase, respectively (P<0.05). Increased hepatic levels of iNOS and GSSG/GSH suggest elevated oxidative stress with a higher number of macrophages in the adipose tissue in HFRD-fed mice (P<0.05). Significantly elevated rates of hepatocyte apoptosis (∼2.4-fold), as determined by TUNEL analysis with increased Bax/Bcl2 ratio and PARP-1 levels (∼2- and 1.5-fold, respectively), were observed in HFRD-fed mice. Thus, HFRD exposure increased hepatic steatosis accompanied by oxidative stress and inflammation, leading to hepatocyte apoptosis.

The influence of fibroblast on the arachnoid leptomeningeal cells in vitro

OBJECTIVE

Fibroblast is pervasive in the setting of injury. Its invasion into the arachnoid tissue causes scarring, cortical adhesion of the brain, and obstruction of cerebrospinal fluid outflow. The purpose of this study is to determine the phenotypic and physiologic effects of fibroblasts on arachnoid in culture.

METHODS

We studied the effects of fibroblast on the arachnoid cell growth, motility, phenotypic changes, and transport properties. Immortalized rat (Rattus norvegicus, Sprague Dawley breed) arachnoid cells were grown with fibroblast on opposite sides of polyethylene membranes or co-cultured in plastic wells. Arachnoid cell growth rate and DNA content, morphology, transport physiology, and extracellular matriceal content were determined in the presence of normal and irradiated fibroblast cells.

RESULTS

When arachnoid cells were grown in the presence of fibroblasts, mannitol permeability increased and transepithelial electrical resistance (TEER) decreased. Arachnoid cell growth rate also significantly decreased. When arachnoid cells were grown in close proximity (i.e. on the same monolayer) with fibroblasts, the arachnoid cells were overrun by day 2, yet when physically separated, no significant change was seen in growth. Apoptosis increased markedly in arachnoid cultures in the presence of fibroblast. Fibroblast caused arachnoid cell to exhibit avoidance behavior, and irradiated fibroblast induced arachnoidal cells to move faster and exhibited greater directional changes. Subcellular glycosaminoglycan (GAG) content was significantly altered by fibroblast.

INTERPRETATION

Fibroblasts influence arachnoid cell's mannitol transport likely via soluble factors. While the arachnoid cells did not change morphologically, cell growth was influenced. Over time, the cells had profound changes in transport and motility. The immortalized arachnoid cell/fibroblast culture system provides a unique model mimicking the pathologic event of leptomeningeal scarring.

Knockdown of HIF-1α and IL-8 induced apoptosis of hepatocellular carcinoma triggers apoptosis of vascular endothelial cells

A local hypoxic microenvironment is one of the most important characteristics of solid tumors. Hypoxia inducible factor-1α (HIF-1α) and Interleukin-8 (IL-8) activate tumor survival from hypoxic-induced apoptosis in each pathway. This study aimed to evaluate whether knockdown of HIF-1α and IL-8 induced apoptosis of the hepatocellular carcinoma (HCC) and endothelial cell lines. HCC cell lines were infected with adenovirus-expressing shRNA for HIF-1α and IL-8 and maintained under hypoxic conditions (1% O2, 24 h). The expression levels of HIF-1α and both apoptotic and growth factors were examined by real-time quantitative PCR and western blot. We also investigated apoptosis by TUNEL assay (FACS and Immunofluorescence) and measured the concentration of cytochrome C. Inhibition of HIF-1α and IL-8 up-regulated the expression of apoptotic factors while downregulating anti-apoptotic factors simultaneously. Knockdown of HIF-1α and IL-8 increased the concentration of cytochrome C and enhanced DNA fragmentation in HCC cell lines. Moreover, culture supernatant collected from the knockdown of HIF-1α and IL-8 in HCC cell lines induced apoptosis in human umbilical vein endothelial cells under hypoxia, and the expression of variable apoptotic ligand increased from HCC cell lines, time-dependently. These data suggest that adenovirus-mediated knockdown of HIF-1α and IL-8 induced apoptosis in HCC cells and triggered apoptosis of vascular endothelial cells.

Macrophage Depletion Attenuates Extracellular Matrix Deposition and Ductular Reaction in a Mouse Model of Chronic Cholangiopathies

Chronic cholangiopathies, such as primary and secondary sclerosing cholangitis, are progressive disease entities, associated with periportal accumulation of inflammatory cells, encompassing monocytes and macrophages, peribiliary extracellular matrix (ECM) deposition and ductular reaction (DR). This study aimed to elucidate the relevance of macrophages in the progression of chronic cholangiopathies through macrophage depletion in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse model. One group of mice received a single i.p. injection of Clodronate encapsulated liposomes (CLOLipo) at day 7 of a 14 day DDC treatment, while control animals were co-treated with PBSLipo instead. Mice were sacrificed after 7 or respectively 14 days of treatment for immunohistochemical assessment of macrophage recruitment (F4/80), ECM deposition (Sirius Red, Laminin) and DR (CK19). Macrophage depletion during a 14 day DDC treatment resulted in a significant inhibition of ECM deposition. Porto-lobular migration patterns of laminin-rich ECM and ductular structures were significantly attenuated and a progression of DR was effectively inhibited by macrophage depletion. CLOLipo co-treatment resulted in a confined DR to portal regions without amorphous cell clusters. This study suggests that therapeutic options selectively directed towards macrophages might represent a feasible treatment for chronic cholestatic liver diseases.

The Neuron-Specific Protein TMEM59L Mediates Oxidative Stress-Induced Cell Death

TMEM59L is a newly identified brain-specific membrane-anchored protein with unknown functions. Herein we found that both TMEM59L and its homolog, TMEM59, are localized in Golgi and endosomes. However, in contrast to a ubiquitous and relatively stable temporal expression of TMEM59, TMEM59L expression was limited in neurons and increased during development. We also found that both TMEM59L and TMEM59 interacted with ATG5 and ATG16L1, and that overexpression of them triggered cell autophagy. However, overexpression of TMEM59L induced intrinsic caspase-dependent apoptosis more dramatically than TMEM59. In addition, downregulation of TMEM59L prevented neuronal cell death and caspase-3 activation caused by hydrogen peroxide insults and reduced the lipidation of LC3B. Finally, we found that AAV-mediated knockdown of TMEM59L in mice significantly ameliorated caspase-3 activation, increased mouse duration in the open arm during elevated plus maze test, reduced mouse immobility time during forced swim test, and enhanced mouse memory during Y-maze and Morris water maze tests. Together, our study indicates that TMEM59L is a pro-apoptotic neuronal protein involved in animal behaviors such as anxiety, depression, and memory, and that TMEM59L downregulation protects neurons against oxidative stress.

Apoptosis induced by a low-carbohydrate and high-protein diet in rat livers

AIM: To determine whether high-protein, high-fat, and low-carbohydrate diets can cause lesions in rat livers.

METHODS: We randomly divided 20 female Wistar rats into a control diet group and an experimental diet group. Animals in the control group received an AIN-93M diet, and animals in the experimental group received an Atkins-based diet (59.46% protein, 31.77% fat, and 8.77% carbohydrate). After 8 wk, the rats were anesthetized and exsanguinated for transaminases analysis, and their livers were removed for flow cytometry, immunohistochemistry, and light microscopy studies. We expressed the data as mean ± standard deviation (SD) assuming unpaired and parametric data; we analyzed differences using the Student’s t-test. Statistical significance was set at P < 0.05.

RESULTS: We found that plasma alanine aminotransferase and aspartate aminotransferase levels were significantly higher in the experimental group than in the control group. According to flow cytometry, the percentages of nonviable cells were 11.67% ± 1.12% for early apoptosis, 12.07% ± 1.11% for late apoptosis, and 7.11% ± 0.44% for non-apoptotic death in the experimental diet group and 3.73% ± 0.50% for early apoptosis, 5.67% ± 0.72% for late apoptosis, and 3.82% ± 0.28% for non-apoptotic death in the control diet group. The mean percentage of early apoptosis was higher in the experimental diet group than in the control diet group. Immunohistochemistry for autophagy was negative in both groups. Sinusoidal dilation around the central vein and small hepatocytes was only observed in the experimental diet group, and fibrosis was not identified by hematoxylin-eosin or Trichrome Masson staining in either group.

CONCLUSION: Eight weeks of an experimental diet resulted in cellular and histopathological lesions in rat livers. Apoptosis was our principal finding; elevated plasma transaminases demonstrate hepatic lesions.

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.

Plant-based vaccines: novel and low-cost possible route for Mediterranean innovative vaccination strategies

A plant bioreactor has enormous capability as a system that supports many biological activities, that is, production of plant bodies, virus-like particles (VLPs), and vaccines. Foreign gene expression is an efficient mechanism for getting protein vaccines against different human viral and nonviral diseases. Plants make it easy to deal with safe, inexpensive, and provide trouble-free storage. The broad spectrum of safe gene promoters is being used to avoid risk assessments. Engineered virus-based vectors have no side effect. The process can be manipulated as follows: (a) retrieve and select gene encoding, use an antigenic protein from GenBank and/or from a viral-genome sequence, (b) design and construct hybrid-virus vectors (viral vector with a gene of interest) eventually flanked by plant-specific genetic regulatory elements for constitutive expression for obtaining chimeric virus, (c) gene transformation and/or transfection, for transient expression, into a plant-host model, that is, tobacco, to get protocols processed positively, and then moving into edible host plants, (d) confirmation of protein expression by bioassay, PCR-associated tests (RT-PCR), Northern and Western blotting analysis, and serological assay (ELISA), (e) expression for adjuvant recombinant protein seeking better antigenicity, (f) extraction and purification of expressed protein for identification and dosing, (g) antigenicity capability evaluated using parental or oral delivery in animal models (mice and/or rabbit immunization), and (h) growing of construct-treated edible crops in protective green houses. Some successful cases of heterologous gene-expressed protein, as edible vaccine, are being discussed, that is, hepatitis C virus (HCV). R9 mimotope, also named hypervariable region 1 (HVR1), was derived from the HVR1 of HCV. It was used as a potential neutralizing epitope of HCV. The mimotope was expressed using cucumber mosaic virus coat protein (CP), alfalfa mosaic virus CP P3/RNA3, and tobacco mosaic virus (TMV) CP-tobacco mild green mosaic virus (TMGMV) CP as expression vectors into tobacco plants. Expressed recombinant protein has not only been confirmed as a therapeutic but also as a diagnostic tool. Herpes simplex virus 2 (HSV-2), HSV-2 gD, and HSV-2 VP16 subunits were transfected into tobacco plants, using TMV CP-TMGMV CP expression vectors.

Apoptosis induced by Fas signaling does not alter hepatic hepcidin expression

AIM: To determine the regulation of human hepcidin (HAMP) and mouse hepcidin (hepcidin-1 and hepcidin-2) gene expression in the liver by apoptosis using in vivo and in vitro experimental models.

METHODS: For the induction of the extrinsic apoptotic pathway, HepG2 cells were treated with various concentrations of CH11, an activating antibody for human Fas receptor, for 12 h. Male C57BL/6NCR and C57BL/6J strains of mice were injected intraperitoneally with sublethal doses of an activating antibody for mouse Fas receptor, Jo2. The mice were anesthetized and sacrificed 1 or 6 h after the injection. The level of apoptosis was quantified by caspase-3 activity assay. Liver injury was assessed by measuring the levels of ALT/AST enzymes in the serum. The acute phase reaction in the liver was examined by determining the expression levels of IL-6 and SAA3 genes by SYBR green quantitative real-time PCR (qPCR). The phosphorylation of transcription factors, Stat3, Smad4 and NF-κB was determined by western blotting. Hepcidin gene expression was determined by Taqman qPCR. The binding of transcription factors to hepcidin-1 promoter was studied using chromatin immunoprecipitation (ChIP) assays.

RESULTS: The treatment of HepG2 cells with CH11 induced apoptosis, as shown by the significant activation of caspase-3 (P < 0.001), but did not cause any significant changes in HAMP expression. Short-term (1 h) Jo2 treatment (0.2 μg/g b.w.) neither induced apoptosis and acute phase reaction nor altered mRNA expression of mouse hepcidin-1 in the livers of C57BL/6NCR mice. In contrast, 6 h after Jo2 injection, the livers of C57BL/6NCR mice exhibited a significant level of apoptosis (P < 0.001) and an increase in SAA3 (P < 0.023) and IL-6 (P < 0.005) expression in the liver. However, mRNA expression of hepcidin-1 in the liver was not significantly altered. Despite the Jo2-induced phosphorylation of Stat3, no occupancy of hepcidin-1 promoter by Stat3 was observed, as shown by ChIP assays. Compared to C57BL/6NCR mice, Jo2 treatment (0.2 μg/g b.w.) of C57BL/6J strain mice for 6 h induced a more prominent activation of apoptosis, liver injury and acute phase reaction. Similar to C57BL/6NCR mice, the level of liver hepcidin-1 mRNA expression in the livers of C57BL/6J mice injected with a sublethal dose of Jo2 (0.2 μg/g b.w.) remained unchanged. The injection of C57BL/6J mice with a higher dose of Jo2 (0.32 μg/g b.w.) did not also alter hepatic hepcidin expression.

CONCLUSION: Our findings suggest that human or mouse hepcidin gene expression is not regulated by apoptosis induced via Fas receptor activation in the liver.

Distinctive intrahepatic characteristics of paediatric and adult pathogenesis of chronic hepatitis C infection

Mechanisms leading to liver damage in chronic hepatitis C (CHC) are being discussed, but both the immune system and the virus are involved. The aim of this study was to evaluate intrahepatic viral infection, apoptosis and portal and periportal/interface infiltrate in paediatric and adult patients to elucidate the pathogenesis of chronic hepatitis C. HCV-infected, activated caspase-3(+) and TUNEL(+) hepatocytes, as well as total, CD4(+), CD8(+), Foxp3(+) and CD20(+) lymphocytes infiltrating portal and periportal/interface tracts were evaluated in 27 paediatric and 32 adult liver samples by immunohistochemistry or immunofluorescence. The number of infected hepatocytes was higher in paediatric than in adult samples (p 0.0078). In children, they correlated with apoptotic hepatocytes (activated caspase-3(+) r = 0.74, p < 0.0001; TUNEL(+) r = 0.606, p 0.0017). Also, infected (p = 0.026) and apoptotic hepatocytes (p = 0.03) were associated with the severity of fibrosis. In adults, activated caspase-3(+) cell count was increased in severe hepatitis (p = 0.009). Total, CD4(+), CD8(+) and Foxp3(+) lymphocyte count was higher in adult samples (p < 0.05). Paediatric CD8(+) cells correlated with infected (r = 0.495, p 0.04) and TUNEL(+) hepatocytes (r = 0.474, p = 0.047), while adult ones correlated with activated caspase-3(+) hepatocytes (r = 0.387, p 0.04). In adults, CD8(+) was associated with hepatitis severity (p < 0.0001) and correlated with inflammatory activity (CD8(+) r = 0.639, p 0.0003). HCV, apoptosis and immune response proved to be involved in CHC pathogenesis of both paediatric and adult patients. However, liver injury in paediatric CHC would be largely associated with a viral cytopathic effect mediated by apoptosis, while in adults it would be mainly associated with an exacerbated immune response.

Effect of bone marrow mesenchymal stem cell transplantation on acute hepatic failure in rats

The aim of the present study was to investigate the effectiveness of bone marrow mesenchymal stem cell (BMSC) transplantation in the treatment of acute hepatic failure (AHF) in rats. BMSCs were isolated from rat bone marrow, cultured and analyzed by flow cytometry. Following BMSC transplantation into rats with AHF, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), direct bilirubin (DBIL) and indirect bilirubin (IBIL) in the serum were measured using an automatic biochemical analyzer. Hematoxylin and eosin (H&E) staining and a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed to analyze the pathological changes and apoptosis rate. Levels of cluster of differentiation (CD)163 and interleukin (IL)-10 in the serum and liver tissue were detected by an enzyme-linked immunosorbent assay (ELISA) assay and western blot analysis. Compared with the levels in the control group, the serum levels of ALT, AST, DBIL, IBIL, CD163 and IL-10 in the BMSC transplantation groups were significantly lower at 120 and 168 h, while the serum levels of ALB were significantly higher at 168 h after BMSC transplantation. The pathological features of liver failure were alleviated by BMSC transplantation. The expression levels of CD163 and IL-10 in the liver tissue were also significantly decreased following transplantation. The results indicate that BMSCs have a therapeutic effect on AHF in rats, and CD163 and IL-10 may be used as sensitive serum prognosis indicators in the early assessment of patients following liver transplantation.

TRAIL enhances apoptosis of human hepatocellular carcinoma cells sensitized by hepatitis C virus infection: therapeutic implications

Hepatitis C virus (HCV) infection causes chronic liver diseases leading to hepatocellular carcinoma (HCC) and liver failure. We have previously shown that HCV sensitizes hepatocytes to mitochondrial apoptosis via the TRAIL death receptors DR4 and DR5. Although TRAIL and its receptors are selective targets for cancer therapy, their potential against HCC with chronic HCV infection has not been explored yet. Here we show that HCV induces DR4/DR5-dependent activation of caspase-8 leading to elevation of apoptotic signaling in infected cells and also present TRAIL effect in HCV-induced apoptotic signaling. HCV induced proteolytic cleavage of caspase-9 by stimulating DR4 and DR5, resulting in subsequent cleavage of caspase-3. Further, HCV-induced proteolytic cleavage in caspase-8, caspase-9, and caspase-3 was enhanced in the presence of recombinant TRAIL. HCV-induced cleavage in caspase-9 and increase in caspase-3/7 activity was completely suppressed by silencing of either DR4 or DR5. Perturbing DR4/DR5-caspase-8 signaling complex by silencing DR4 and DR5 or by chemical inhibitor specific to caspase-8 led to decrease of HCV-induced cleavage of poly(ADP-ribose) polymerase (PARP), a substrate for caspase-3 during apoptosis, indicating the functional role of caspase-8 in HCV-induced apoptotic signaling network. Furthermore, TRAIL enhanced PARP cleavage in apoptotic response induced by HCV infection, indicating the effect of TRAIL for the induction of selective apoptosis of HCC cells infected with HCV. Given the importance of apoptosis in HCC development, our data suggest that HCV-induced DR4 and DR5 may be considered as an attractive target for TRAIL therapy against HCC with chronic HCV infection.

Serum cytochrome c and m30-neoepitope of cytokeratin-18 in chronic hepatitis C

BACKGROUND & AIMS

Cytochrome c (CYC) and M30-neoepitope of cytokeratin-18 (M30-CK18) are involved at different levels in apoptotic pathways. We aimed to evaluate an association between serum CYC, M30-CK18 and disease activity as well response to therapy in chronic hepatitis C (CHC).

METHODS

Seventy CHC patients were enrolled in this study. Forty five of them completed pegylated interferon plus ribavirin therapy. Histopathological evaluation of hepatic inflammatory activity and fibrosis, as well as blood liver function tests, was performed. Serum concentrations of M30-CK18 and CYC were measured by ELISA.

RESULTS

Median serum concentration of M30-CK18 was higher in CHC patients [283 U/L] vs. control [113 U/L] (P = 0.0003) and was associated with inflammatory activity and liver fibrosis (P < 0.001). Serum M30-CK18 positively correlated with serum activity of ALT and GGT. CYC was not detected in sera of control group, whereas in CHC, 41.43% patients had detectable CYC in serum samples [0.60 ng/ml]. Detectable baseline serum CYC had been negatively associated with sustained virological response (SVR). In patients with detectable CYC, SVR rate was 20% vs. 60% in patients with undetectable CYC (P = 0.007).

CONCLUSIONS

Elevated serum M30-CK18, as an indicator of enhanced apoptosis of hepatocytes, parallels active hepatic inflammation and fibrosis but also biochemical activity in CHC; thus, it may serve as a comprehensive non-invasive marker of disease activity. On the other hand, detection of serum CYC at baseline may be negatively associated with treatment response to pegylated interferon plus ribavirin in CHC.

The role of bone marrow mesenchymal stem cells in the treatment of acute liver failure

Objective. This study is to investigate the effects of bone marrow mesenchymal stem cell (BMSC) transplantation on acute liver failure (ALF). Methods. BMSCs were separated from rat bone marrow, cultured, and identified by flow cytometry. Rat model with ALF was established by injecting D-galactosamine and lipopolysaccharide. Rats were randomly divided into the control group and BMSC transplantation group. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured at 24 h, 120 h, and 168 h after BMSC transplantation. Apoptosis was detected by TUNEL assay. The expression of VEGF and AFP proteins was detected by immunofluorescence. Caspase-1 and IL-18 proteins and mRNA were detected by immunohistochemistry and RT-PCR. Results. Compared with the control group, levels of ALT, AST, caspase-1 and IL-18 proteins, and mRNA in the transplantation group were significantly lower at 120 h and 168 h after BMSCs transplantation. Apoptosis was inhibited by BMSCs transplantation. The VEGF protein levels were increased with the improvement of liver function, and the AFP protein levels were increased with the deterioration of the liver function after BMSCs transplantation. Conclusions. BMSCs transplantation can improve liver function and inhibit hepatocyte apoptosis as well as promote hepatocyte proliferation in rat model with ALF.

Caspase-cleaved fragments of cytokeratin-18 as a marker of inflammatory activity in chronic hepatitis B virus infection

BACKGROUND

The differential diagnosis between inactive carrier and active hepatitis is important in patients with chronic hepatitis B (CHB) virus infection. Serum cytokeratin (CK)-18 fragments (M30-antigen) are proposed as biomarkers of apoptosis.

OBJECTIVES

We investigated whether serum M30-antigen levels might help to characterize the various phases of CHB and predict the state of significant inflammation in patients with CHB.

STUDY DESIGN

A total of 339 CHB patients who underwent liver biopsy, were included. Serum M30-antigen levels were compared between inactive carriers (n=21), patients with HBeAg-negative hepatitis (n=95), HBeAg-positive hepatitis (n=141) and liver cirrhosis (n=82).

RESULTS

Serum M30-antigen levels were correlated significantly not only with AST (r=0.544, p<0.001) and ALT (r=0.315, p<0.001) and but also inflammatory grading score on liver biopsy (r=0.240, p<0.001). Serum M30-antigen level in HBeAg-negative CHB was significantly higher than that of inactive HBV carrier (399.78 U/L vs 148.90 U/L, p<0.001). Multivariate analysis showed that AST (p<0.001), albumin (p=0.009) and M30-antigen (p=0.020) were the independent predictors of significant inflammation. Combined serum M30-antigen level (>344 U/L) and AST (>78 IU/L) measurement provided the most accurate identification of significant inflammation, showing 38.2% sensitivity, 96.1% specificity, 91.0% positive predictive value and 56.1% negative predictive value.

CONCLUSIONS

Serum M30-antigen can be a predictive marker for distinguishing between inactive carrier and HBeAg-negative CHB. Serum M30 levels are associated with the presence of significant inflammation, especially in patients with normal or minimally elevated ALT in CHB patients.

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.

Hepatoprotective effects of reynosin against thioacetamide-induced apoptosis in primary hepatocytes and mouse liver

The aim of this study was to identify the hepatoprotective effects of reynosin, sesquiterpenes from the leaves of Laurus nobilis, against thioacetamide (TAA)-induced apoptosis in primary hepatocyte cultures and an in vivo mouse model. Rat hepatocytes were isolated and pretreated with 0.13, 0.64, or 3.22 μM reynosin and then exposed to 100 mM TAA. Reynosin treatment significantly inhibited TAA-induced apoptosis and hepatocellular DNA damage in primary rat hepatocytes. We observed an increase in levels of antiapoptotic Bcl-2, Bcl-XL mRNA and a decrease in levels of proapoptotic Bax mRNA following reynosin treatment of hepatocytes. Apoptosis in BALB/c mice was induced with intra-peritoneal injection of 200 mg/kg TAA for 2 weeks every other day. Then reynosin (5 mg/kg) and TAA were intragastrically given for 3 weeks every other day. Aspartate aminotransferase and alanine aminotransferase levels in the blood of mice were decreased in the reynosin administration group. Bcl-2 and Bcl-XL mRNA levels were increased, and the Bax mRNA level was decreased in reynosin-treated mice. Thus, reynosin inhibited TAA-induced apoptosis in primary hepatocytes and an in vivo mouse model.

Serum apoptosis markers related to liver damage in chronic hepatitis C: sFas as a marker of advanced fibrosis in children and adults while M30 of severe steatosis only in children

Background

Liver biopsy represents the gold standard for evaluating damage and progression in patients with chronic hepatitis C (CHC); however, developing noninvasive tests that can predict liver injury represents a growing medical need. Considering that hepatocyte apoptosis plays a role in CHC pathogenesis; the aim of our study was to evaluate the presence of different apoptosis markers that correlate with liver injury in a cohort of pediatric and adult patients with CHC.

Methods

Liver biopsies and concomitant serum samples from 22 pediatric and 22 adult patients with CHC were analyzed. Histological parameters were evaluated. In serum samples soluble Fas (sFas), caspase activity and caspase-generated neoepitope of the CK-18 proteolytic fragment (M30) were measured.

Results

sFas was associated with fibrosis severity in pediatric (significant fibrosis p = 0.03, advanced fibrosis p = 0.01) and adult patients (advanced fibrosis p = 0.02). M30 levels were elevated in pediatric patients with severe steatosis (p = 0.01) while in adults no relation with any histological variable was observed. Caspase activity levels were higher in pediatric samples with significant fibrosis (p = 0.03) and they were associated with hepatitis severity (p = 0.04) in adult patients. The diagnostic accuracy evaluation demonstrated only a good performance for sFas to evaluate advanced fibrosis both in children (AUROC: 0.812) and adults (AUROC: 0.800) as well as for M30 to determine steatosis severity in children (AUROC: 0.833).

Conclusions

Serum sFas could be considered a possible marker of advanced fibrosis both in pediatric and adult patient with CHC as well as M30 might be a good predictor of steatosis severity in children.

Role of glycogen synthase kinase 3β in the pathogenesis of D-GalN/LPS-induced acute liver injury in mice

AIM: To study the role of glycogen synthase kinase-3β (GSK-3β) in the pathogenesis of acute liver failure (ALF) induced by injection of D-galactosamine/lipopolysaccharide (D-GalN/LPS) in mice.

METHODS: ALF was induced in C57BL/6 mice by intraperitoneal injection of D-GalN/LPS. Animal experimental groups included control group, ALF model group, SB216763 pretreatment group (SB216763 in DMSO, i.p, two hours before the induction of ALF) and SB216763 treatment group (SB216763 in DMSO, i.p, two hours after the induction of ALF). Phosphorylation level of GSK-3β was analyzed by Western blot. Serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured to assess the liver function. HE staining was conducted to analyze histological injury. Inflammatory gene expression was detected by quantitative real-time PCR. The expression of apoptosis-related protein Caspase 3 was detected by Western blot. One-way ANOVA was used for pair-wise comparison of means of multiple samples (homogeneity of variance with LSD-t test, unequal variances with Games-Howell method).

RESULTS: The phosphorylation level of GSK-3β decreased initially and then increased in the progression of ALF. Inhibition of GSK-3β, either by pretreatment or treatment with SB216763, could improve liver function (serum ALT and AST levels decreased significantly, and there was obvious improvement in liver tissue injury), suppress inflammatory responses (inhibition of expression of pro-inflammatory cytokines, such as TNF-α, IL-6 and IL-1β, and promotion of expression of anti-inflammatory cytokine IL-10), and reduced the expression of apoptosis-related protein Caspase 3.

CONCLUSION: GSK-3β is activated in D-GalN/LPS-induced ALF in mice, and inhibition of GSK-3β activity can improve liver injury by reducing inflammation and hepatocyte apoptosis, GSK-3β may be a new target for the treatment of ALF.

Inhibition of glycogen synthase kinase 3β ameliorates D-GalN/LPS-induced liver injury by reducing endoplasmic reticulum stress-triggered apoptosis

Background

Glycogen synthase kinase 3β(GSK3β) is a ubiquitous serine-threonine protein kinase that participates in numerous cellular processes and disease pathophysiology. We aimed to determine therapeutic potential of GSK3β inhibition and its mechanism in a well-characterized model of lipopolysaccharide (LPS)-induced model of acute liver failure (ALF).

Methodology

In a murine ALF model induced by D-GalN(700 mg/kg)/LPS(10 µg/kg), we analyzed GSK3β mechanisms using a specific chemical inhibitor, SB216763, and detected the role of endoplasmic reticulum stress (ERS). Mice were administered SB216763 at 2 h before or after D-GalN/LPS injection, respectively, and then sacrificed 6 h after D-GalN/LPS treatment to evaluate its prophylactic and therapeutic function. The lethality rate, liver damage, ERS, cytokine expression, MAP kinase, hepatocyte apoptosis and expression of TLR 4 were evaluated, respectively. Whether the inhibition of GSK3β activation protected hepatocyte from ERS-induced apoptosis was investigated in vitro.

Principal Findings

GSK3β became quickly activated (dephosphorylated) upon D-GalN/LPS exposure. Administration of SB216763 not only ameliorated liver injury, as evidenced by reduced transaminase levels, and well-preserved liver architecture, but also decreased lethality. Moreover, GSK3β inhibition resulted in down-regulation of pro-apoptotic proteins C/EBP–homologous protein(CHOP) and caspase-12, which are related to ERS. To further demonstrate the role of ERS, we found that GSK3β inhibition protected hepatocyte from ERS-induced cell death. GSK3β inhibition down-regulated the MAPK pathways, reduced expression of inflammatory cytokines and decreased expression of TLR4.

Conclusions

Our findings demonstrate the key function of GSK3β signaling in the pathophysiology of ALF, especially in regulating the ERS, and provide a rationale for targeting GSK3β as a potential therapeutic strategy to ameliorate ALF.

TAT-apoptosis repressor with caspase recruitment domain protein transduction rescues mice from fulminant liver failure

Acute liver failure (ALF) is associated with massive hepatocyte cell death and high mortality rates. Therapeutic approaches targeting hepatocyte injury in ALF are hampered by the activation of distinct stimulus-dependent pathways, mechanism of cell death, and a limited therapeutic window. The apoptosis repressor with caspase recruitment domain (ARC) is a recently discovered death repressor that inhibits both death receptor and mitochondrial apoptotic signaling. Here, we investigated the in vivo effects of ARC fused with the transduction domain of human immunodeficiency virus 1 (HIV-1) (TAT-ARC) on Fas- and tumor necrosis factor (TNF)-mediated murine models of fulminant liver failure. Treatment with TAT-ARC protein completely abrogated otherwise lethal liver failure induced by Fas-agonistic antibody (Jo2), concanavalin A (ConA), or D-galactosamine/lipopolysaccharide (GalN/LPS) administration. Importantly, survival of mice was even preserved when TAT-ARC therapy was initiated in a delayed manner after stimulation with Jo2, ConA, or GalN/LPS. ARC blocked hepatocyte apoptosis by directly interacting with members of the death-inducing signaling complex. TNF-mediated liver damage was inhibited by two independent mechanisms: inhibition of jun kinase (JNK)-mediated TNF-α expression and prevention of hepatocyte apoptosis by inhibition of both death receptor and mitochondrial death signaling. We identified JNK as a novel target of ARC. ARC's caspase recruitment domain (CARD) directly interacts with JNK1 and JNK2, which correlates with decreased JNK activation and JNK-dependent TNF-α production.

CONCLUSION

This work suggests that ARC confers hepatoprotection upstream and at the hepatocyte level. The efficacy of TAT-ARC protein transduction in multiple murine models of ALF demonstrates its therapeutic potential for reversing liver failure.

Bile acids: from digestion to cancers

Bile acids (BAs) are cholesterol metabolites that have been extensively studied these last decades. BAs have been classified in two groups. Primary BAs are synthesized in liver, when secondary BAs are produced by intestinal bacteria. Recently, next to their ancestral roles in digestion and fat solubilization, BAs have been described as signaling molecules involved in many physiological functions, such as glucose and energy metabolisms. These signaling pathways involve the activation of the nuclear receptor FXRα or of the G-protein-coupled receptor TGR5. These two receptors have selective affinity to different types of BAs and show different expression patterns, leading to different described roles of BAs. It has been suggested for long that BAs could be molecules linked to tumor processes. Indeed, as many other molecules, regarding analyzed tissues, BAs could have either protective or pro-carcinogen activities. However, the molecular mechanisms responsible for these effects have not been characterized yet. It involves either chemical properties or their capacities to activate their specific receptors FXRα or TGR5. This review highlights and discusses the potential links between BAs and cancer diseases and the perspectives of using BAs as potential therapeutic targets in several pathologies.

18α-Glycyrrhizin induces apoptosis and suppresses activation of rat hepatic stellate cells

Background

To investigate the potential mechanisms underlying the protective effects of 18α Glycyrrhizin (GL) on rat hepatic stellate cells (HSCs) and hepatocytes in vivo and in vitro.

Material/Methods

Sprague-Dawley (SD) rats were randomly divided into 5 groups: normal control group, liver fibrosis group, high-dose 18α GL group (25 mg/kg/d), intermediate-dose 18α GL group (12.5 mg/kg/d) and low-dose 18α GL group (6.25 mg/kg/d). The rat liver fibrosis model was induced by carbon tetrachloride (CCl4). The expressions of α-smooth muscle actin (αSMA) and NF-κB were determined by real-time PCR and immunohistochemistry.

Results

18αGL dose-dependently inhibited the CCl4-induced liver fibrosis. There were significant differences in the mRNA and protein expressions of αSMA between the fibrosis group and 18α-GL treatment groups, suggesting that 18α GL can suppress the proliferation and activation of HSCs. Few HSCs were apoptotic in the portal area and fibrous septum in the liver fibrosis group. However, the double-color staining of a-SMA and TUNEL showed that 18α-GL treatment groups increased HSC apoptosis. NF-κB was mainly found in the nucleus in the fibrosis group, while cytoplasmic expression of NF-κB was noted in the 18αGL groups. In the in vitro experiments, 18α GL promoted the proliferation of hepatocytes, but inhibited that of HSCs. HSCs were arrested in the G2/M phase following 18α GL treatment and were largely apoptotic.

Conclusions

18α-GL can suppress the activation of HSCs and induce the apoptosis of HSCs by blocking the translocation of NF-κB into the nucleus, which plays an important role in the protective effect of 18α-GL on liver fibrosis.

Apoptotic effects of a chimeric plant virus carrying a mimotope of the hepatitis C virus hypervariable region 1: role of caspases and endoplasmic reticulum-stress

The role of apoptosis in the persistence of hepatitis C virus (HCV) infection is controversial. Moreover, conflicting data on the modulation of this process by HCV proteins have been provided. We evaluated the susceptibility of peripheral lymphocytes from patients with chronic hepatitis C to apoptosis both spontaneous and after incubation with a chimeric Cucumber mosaic virus (CMV) carrying 180 copies of the synthetic R9 mimotope obtained from more than 200 hypervariable region-1 sequences of HCV. Resting T lymphocytes were found to be sensitized to apoptosis as a result of chronic HCV infection. The plant virus-derived vector R9-CMV displayed a strong pro-apoptotic effect associated with activation of both caspase-8 and −9, indicating the involvement of both extrinsic and intrinsic apoptotic pathways. A parallel R9-CMV-mediated activation of endoplasmic reticulum-stress was suggested by the significant induction of BiP/GRP78, GADD153 and caspase-12. These data contribute to define the complex HCV/host interaction, and open new prospects for developing a plant-derived antigen-presenting system to strengthen host defences against persistent pathogens.

Foxp3 expression in liver correlates with the degree but not the cause of inflammation

Patients with chronic viral hepatitis display increased expression of Foxp3 in liver, suggesting that Tregs expansion contributes to persistent infection. The purpose of this study was to elucidate whether the expression of Foxp3 relates not to the viral infection but to the resulting liver inflammation. Liver biopsies obtained from 69 individuals (26 chronic HBV hepatitis, 14 chronic HCV hepatitis, 11 nonalcoholic fatty liver disease, 8 autoimmune diseases, 2 methotrexate-related toxicity, and 8 controls) were examined, by qRT-PCR, for the mRNA expression of Foxp3, IL-10, TGF-β1, Fas, FasL, TRAIL, caspase-3, TNF-α, IFN-γ, and IL-1β. Significant increase of Foxp3 was observed in all disease groups compared to controls, which was positively correlated with the intensity of inflammation. The expression of the apoptosis mediators Fas, FasL, and TRAIL, but not of IL-10 and TGF-β1, was also significantly elevated. Our findings indicate that, independently of the initial inducer, liver inflammation is correlated with elevated expression of apoptosis mediators and is followed by local Treg accumulation. Further research towards the elucidation of the underlying casual relationships is required, in order to clarify whether our results signify the existence of a uniform Treg-mediated regulatory mechanism of apoptosis-induced inflammation.

Molecular targeting of CSN5 in human hepatocellular carcinoma: a mechanism of therapeutic response

Development of targeted therapy for hepatocellular carcinoma (HCC) remains a major challenge. We have recently identified an elevated expression of the fifth subunit of COP9 signalosome (CSN5) in early HCC as compared to dysplastic stage. In the present study, we explored the possibility of CSN5 being a potential therapeutic target for HCC. Our results show that CSN5 knockdown by small interfering (si) RNA caused a strong induction of apoptosis and inhibition of cell cycle progression in HCC cells in vitro. The downregulation of CSN5 was sufficient to interfere with CSN function as evidenced by the accumulation of neddylated Cullin1 and changes in the protein levels of CSN controlled substrates SKP2, p53, p27 and NF-kB, albeit to a different degree depending on the HCC cell line, which could account for the CSN5 knockdown phenotype. The transcriptomic analysis of CSN5 knockdown signature showed that the anti-proliferative effect was driven by a common subset of molecular alterations including downregulation of CDK6 and ITGB1, which were functionally interconnected with key oncogenic regulators MYC and TGFβ1 involved in the control of proliferation, apoptotic cell death and HCC progression. Consistent with microarray analysis, western blotting revealed that CSN5 depletion increased phosphorylation of Smad 2/3, key mediators of TGFβ1 signaling, decreased the protein levels of ITGB1, CDK6, and cyclin D1 and caused reduced expression of anti-apoptotic Bcl-2 while elevating the levels of pro-apoptotic Bak. A chemically modified variant of CSN5 siRNA was then selected for in vivo application based on the growth inhibitory effect and minimal induction of unwanted immune response. Systemic delivery of the CSN5 3/8 variant by stable-nucleic-acid-lipid-particles (SNALP) significantly suppressed the tumor growth in Huh7-luc⁺ orthotopic xenograft model. Taken together, these results indicate that CSN5 plays a pivotal role in HCC pathogenesis and maybe an attractive molecular target for systemic HCC therapy.

Apoptosis in nonalcoholic fatty liver disease: diagnostic and therapeutic implications

Pathological increases in cell death in the liver as well as in peripheral tissues has emerged as an important mechanism involved in the development and progression of nonalcoholic fatty liver disease (NAFLD). An increase in hepatocyte cell death by apoptosis is typically present in patients with NAFLD and in experimental models of steatohepatitis, while an increase in adipocyte cell death in visceral adipose tissue may be an important mechanism triggering insulin resistance and hepatic steatosis. The two fundamental pathways of apoptosis, the extrinsic (death receptor-mediated) and intrinsic (organelle-initiated) pathways, are both involved. This article summarizes the current knowledge related to the distinct molecular and biochemical pathways of cell death involved in NAFLD pathogenesis. In particular, it will highlight the efforts for the development of both novel diagnostic and therapeutic strategies based on this knowledge.

HIV infection increases HCV-induced hepatocyte apoptosis

BACKGROUND & AIMS

HCV related liver disease is one of the most important complications in persons with HIV, with accelerated fibrosis progression in coinfected persons compared to those with HCV alone. We hypothesized that HCV-HIV coinfection increases HCV related hepatocyte apoptosis and that HCV and HIV influence TRAIL signaling in hepatocytes.

METHODS

We analyzed the effect of HIV in JFH1-infected Huh7.5.1 cells. Apoptosis was measured by Caspase-Glo 3/7 assay and Western blotting for cleaved PARP. TRAIL, TRAIL receptor 1 (DR4), and 2 (DR5) mRNA and protein levels were assessed by real-time PCR and Western blot, respectively. We also investigated activation of caspase pathways using caspase inhibitors and assessed expression of Bid and cytochrome C.

RESULTS

We found increased caspase 3/7 activity and cleaved PARP in JFH1 HCV-infected Huh7.5.1 cells in the presence of heat-inactivated HIV, compared to Huh7.5.1 cells infected with JFH1 or exposed to heat-inactivated HIV alone. Both DR4 and DR5 mRNA and protein expression were increased in JFH1-infected cells in the presence of inactivated HIV compared to Huh7.5.1 cells infected with JFH1 or exposed to heat-inactivated HIV alone. Pancaspase, caspase-8, and caspase-9 inhibition blocked apoptosis induced by HCV, inactivated HIV, and HCV plus inactivated HIV. A caspase-9 inhibitor blocked apoptosis induced by HCV, HIV, and HCV-HIV comparably to pancaspase and caspase-8 inhibitors. HCV induced the activation of Bid cleavage and cytochrome C release. The addition of HIV substantially augmented this induction.

CONCLUSIONS

Our findings indicate that hepatocyte apoptosis is increased in the presence of HCV and HIV compared to HCV or HIV alone, and that this increase is mediated by DR4 and DR5 up-regulation. These results provide an additional mechanism for the accelerated liver disease progression observed in HCV-HIV co-infection.

Gadolinium chloride, a Kupffer cell inhibitor, attenuates hepatic injury in a rat model of chronic cholestasis

The aim of the current study was to elucidate the effect of Kupffer cells inhibition on hepatic injury induced by chronic cholestasis. Sprague-Dawley rats underwent bile duct ligation (BDL) or sham operation and were treated with either saline solution or gadolinium chloride (GdCl(3), a specific Kupffer cell inhibitor, 20 mg/kg i.p. daily). Serum and liver samples were collected after 28 days. Direct and total bilirubin concentrations and serum enzyme activities of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyl transpeptidase (GGT) increased following BDL (p < 0.01). On the contrary to bilirubin concentrations and AST activity, GdCl(3) partially prevented the elevation in ALP, ALT and GGT enzyme activities (p < 0.05). GdCl(3) alleviated lipid peroxidation (reflected by malondialdehyde [MDA] concentration) and increased the activities of antioxidant enzymes (i.e. catalase and glutathione peroxidase) in liver samples after BDL (p < 0.05). Fibrosis, ductular proliferation and portal inflammation were also scored in liver samples. Among morphological changes appeared following BDL (i.e. marked fibrosis, portal inflammation and ductular proliferation); only ductular proliferation was not alleviated by GdCl(3). Therefore, Kupffer cells inhibition has beneficial effects against the development of hepatic injury induced by chronic cholestasis.

Apoptosis as a mechanism for liver disease progression

Hepatocyte injury is ubiquitous in clinical practice, and the mode of cell death associated with this injury is often apoptosis, especially by death receptors. Information from experimental systems demonstrates that hepatocyte apoptosis is sufficient to cause liver hepatic fibrogenesis. The mechanisms linking hepatocyte apoptosis to hepatic fibrosis remain incompletely understood, but likely relate to engulfment of apoptotic bodies by professional phagocytic cells and stellate cells, and release of mediators by cells undergoing apoptosis. Inhibition of apoptosis with caspase inhibitors has demonstrated beneficial effects in murine models of hepatic fibrosis. Recent studies implicating Toll-like receptor 9 in liver injury and fibrosis are also of particular interest. Engulfment of apoptotic bodies is one mechanism by which the TLR9 ligand (CpG DNA motifs) could be delivered to this intracellular receptor. These concepts suggest therapy focused on interrupting the cellular mechanisms linking apoptosis to fibrosis would be useful in human liver diseases.

Prohibitin deficiency blocks proliferation and induces apoptosis in human hepatoma cells: molecular mechanisms and functional implications

Prohibitin is a multifunctional protein participating in a plethora of essential cellular functions, such as cell signaling, apoptosis, survival and proliferation. In the liver, deficient prohibitin activity participates in the progression of non-alcoholic steatohepatitis and obesity, according to mechanisms that still must be elucidated. In this study, we have used a combination of transcriptomics and proteomics technologies to investigate the response of human hepatoma PLC/PRF/5 cells to prohibitin silencing to define in detail the biological function of hepatic Phb1 and to elucidate potential prohibitin-dependent mechanisms participating in the maintenance of the transformed phenotype. Abrogation of prohibitin reduced proliferation and induced apoptosis in human hepatoma cells in a mechanism dependent on NF kappaB signaling. Moreover, down-regulation of ERp29 together with down-regulation of Erlin 2 suggests ER stress. In agreement, increased C/EBP homologous protein levels, poly-ADP ribose polymerase cleavage and activation of caspase 12 and downstream caspase 7 evidenced ER stress-induced apoptosis. Down-regulation of proteasome activator complex subunit 2 and stathmin as well as accumulation of ubiquitinated proteins suggest interplay between ER stress and proteasome malfunction. Taken together, our results provide evidences for prohibitin having a central role in the maintenance of the transformed and invasive phenotype of human hepatoma cells and may further support previous studies suggesting prohibitin as a potential clinical target.

Cholestasis induces apoptosis in mice cardiac cells: the possible role of nitric oxide and oxidative stress

BACKGROUND/AIMS

Acute cholestasis is associated with cardiovascular complications. The purpose of the present study was to investigate the effect of cholestasis on heart apoptosis and the involvement of nitric oxide (NO) and oxidative stress in the possible altered apoptosis of cholestatic hearts.

METHODS

Cholestasis was induced by bile duct-ligation, and sham-operated mice served as controls. Three days after the surgery, heart tissues were evaluated for apoptosis and the level of malondialdehyde (MDA), and the activities of catalase (CAT), glutathione peroxidase (GSHPx) and superoxide dismutase (SOD) have been studied in cardiac tissues. The role of treatment with l-NAME, a non-selective inhibitor of NO synthase, or with d-NAME, an inactive isomer of l-NAME, on cholestatic and sham cardiac apoptosis, level of MDA and CAT, SOD and GSHPx activities was also investigated. The content of NO in cardiac tissue was also determined.

RESULTS

Cholestatic hearts showed structural abnormalities and increased apoptosis compared with sham hearts. Treatment with l-NAME, but not d-NAME, improved both structural abnormalities and enhanced apoptosis of cholestatic hearts. Cholestatic hearts also had an increased level of MDA and decreased activities of CAT and GSHPx, which were not modified by d-NAME treatment. By l-NAME treatment, the level of MDA decreased and activities of CAT, GSHPx and SOD increased in BDL mice. The content of NO was higher in cholestatic cardiac tissue, which was decreased by l-NAME treatment.

CONCLUSION

In conclusion, apoptosis in cholestatic heart might have occurred because of NO overproduction, which could induce oxidative stress in the heart of cholestatic mice.

Salvianolic acid B attenuates hepatocyte apoptosis by regulating mediators in death receptor and mitochondrial pathways

Salvianolic acid B (Sal B) is a water-soluble compound found in the traditional Chinese medicine, Radix Salviae miltiorrhizae, and has been widely used to treat a variety of diseases in Asian cultures. Sal B was shown to inhibit apoptosis in many cell types, but its effect on hepatocyte apoptosis is unknown. In this study, we attempt to show that Sal B attenuates hepatocyte apoptosis and hepatic injury induced by lipopolysaccharide and D-galactosamine in mice. Sal B also inhibits apoptosis that is induced by the death receptor in the HL-7702 hepatocyte cell line. Apoptosis in vitro is determined by flow cytometry, DNA electrophoresis and high content screening assay. The antiapoptotic effect is generated by reducing the expression of tumor necrosis factor alpha receptor type 1, balancing the expression of Bcl-2 family members, decreasing the release of cytochrome C from the mitochondria into the cytosol and inhibiting activated Caspase-3. These findings suggest that Sal B can effectively inhibit hepatocyte apoptosis as well as the underlying mechanisms related to regulating mediators in death receptor and mitochondrial pathways.

Hyperbaric oxygen therapy protects the liver from apoptosis caused by ischemia-reperfusion injury in rats

PURPOSE

: The present paper aimed to investigate the role of hyperbaric oxygen treatment (HBO) and the apoptosis in rat liver ischemia-reperfusion injury (IRI).

METHODS

: Thirty-seven male Wistar rats were subjected to 30 minutes of hepatic ischemia and 30 minutes of reperfusion and randomly distributed into six groups: G-I/R (n = 8), control without HBO; G-HBO/I (n = 8), HBO only during the ischemia period; G-HBO/R (n = 8), HBO only during the reperfusion period; G-HBO-I/R (n = 8), HBO during both the ischemia and reperfusion periods; G-Sh (n = 3), HBO without ischemia or reperfusion as sham group; G-C (n = 2) for control of current apoptosis expression on the normal liver tissue. HBO was carried out using a transparent, cylindrical acrylic chamber with a pressure of 2.0 ATA. Hepatic samples were stained for caspase-3 cleavage.

RESULTS

: Apoptotic cells were identified in all groups. In the hepatic specimens of animals HBO-treated during ischemia (GHBO-I), there was a significant decrease (P < 0.001) in the number of cells undergoing apoptosis (1.62 +/- 0.91). The apoptotic index showed no significant difference in the animals HBO-treated during ischemia/reperfusion (5.75 +/- 1.28) compared with the G-I/R (3.5 +/- 0.75), which had no HBO treatment. The apoptosis index (11.25 +/- 1.90) was significantly higher (P < 0.01) in HBO-treated animals during the reperfusion period when compared with any of the other groups.

CONCLUSION

: A favorable effect was obtained when hyperbaric oxygen was administered early during ischemia. The hyperbaric oxygen in later periods of reperfusion was associated with a more severe apoptosis index. (c) 2009 Wiley-Liss, Inc. Microsurgery 2009.

Tumour necrosis factor-alpha and soluble Fas ligand as biomarkers in non-acetaminophen-induced acute liver failure

OBJECTIVES

Cytokines as prognostic markers in acute liver failure (ALF) have not been evaluated in the Indian subcontinent with hepatitis E as the commonest aetiological agent. We investigated the clinical significance of proinflammatory/apoptotic cytokines soluble Fas ligand (sFasL) and tumour necrosis factor (TNF)-alpha in ALF of specific aetiology.

METHODS

A total of 82 cases, 37 ALF and 45 acute hepatitis (AH), and 60 healthy controls were recruited. Serum levels of sFasL and TNF-alpha were determined at admission and death/recovery.

RESULTS

Mean sFasL and TNF-alpha serum levels at admission were significantly higher (p < 0.001) in patients with ALF than AH, but no marked difference was observed between ALF-E (expired, n = 23) and ALF-S (survivors, n = 14), although the former had comparatively higher levels. ALF-E had higher than baseline TNF-alpha and sFasL concentrations at death, while in the ALF-S group the samples obtained from the patients as soon as they came out of encephalopathy, showed either lower or similar TNF-alpha and sFasL levels as found at admission.

CONCLUSION

The high levels of sFasL and TNF-alpha are associated with ALF. Following the trend of these cytokines can be useful in predicting death and timely referral to a transplant centre.

"Hypothesis of seven balances": molecular mechanisms behind alcoholic liver diseases and association with PPARalpha

OBJECTIVES

The purpose of this review to collate current leading scientific advances of molecular mechanisms in alcoholic liver diseases and to propose a working "hypothesis of seven balances" in relation to peroxisome proliferator activated receptor alpha (PPARalpha), which has important roles in fatty acid oxidation, oxidative stress, inflammatory responses, and possibly liver fibrosis.

METHODS

We conducted an extensive literature review of over a hundred publications and collated the findings with evidence generated in our laboratory.

RESULTS

Our research points to a working hypothesis of seven balances for alcoholic liver diseases consisting of: 1) ethanol oxidation balance in hepatocytes; 2) PPAR alpha activities in liver; 3) fatty acid metabolism balance in hepatic mitochondria; 4) gastrointestinal response to ethanol, acetaldehyde and lipopolysaccharide (LPS); 5) Kupffer cells response to LPS, oxidative stress and inflammatory cytokines; 6) adiponectin levels in plasma interchangeably regulated by tumor necrosis factor-alpha (TNF-alpha); and 7) stellate cells response to all of the above promoting hepatic fibrosis. Cellular mechanisms behind alcoholic liver diseases reveal close temporal associations of PPARalpha, adiponectin, TNF-alpha, cellular inflammation, proliferation, and potentially fibrosis as illustrated in "the hypothesis of seven balances."

CONCLUSIONS

The regulation and adjustment of PPARalpha activation underlying the balance of molecular cascades might resolve the progression of alcoholic liver diseases by reducing oxidative stress and inflammatory effects induced by nuclear factor-kappaB as well as the associated adiponectin pathway. Further elucidation of these pathways would reveal exciting new prospects for treating alcoholic liver diseases and other related liver disorders.