Reduction of alcohol-induced mitochondrial damage with ginsenoside Rg1 studied by atomic force microscopy

The quantification of mitochondrial morphology and mechanical properties is useful for the diagnosis and treatment of mitochondrial and alcoholic liver disease. In this study, the effects of ginsenoside Rg1 (G-Rg1) on the morphology and mechanical properties of mitochondria that had suffered alcohol-induced damage were investigated under near-physiological conditions. Additionally, the morphological and mechanical properties of mitochondria were quantified through atomic force microscopy. Atomic force microscopy revealed that alcohol-induced significant morphological changes in mitochondria. Compared with that of the mitochondria of normal hepatocytes, the average surface area of the damaged mitochondria was found to have increased significantly under the influence of alcohol. Furthermore, the mitochondrial area tended to be normal under the action of G-Rg1, whilst other parameters (length, width and perimeter) were significantly different from those of the mitochondria with the alcohol-induced damage. Simultaneously, alcohol significantly reduced the adhesion and elastic modulus of mitochondria, whilst the adhesion and elastic modulus of mitochondria in the G-Rg1 treatment group were closer to the values of normal mitochondria. This study overall showed that G-Rg1 could effectively alleviate the swelling and anomalous mechanical properties of mitochondria induced by alcohol.

Attenuation of alcohol-induced hepatocyte damage by ginsenoside Rg1 evaluated using atomic force microscopy

Alcoholic liver disease is an important cause of death worldwide. Hepatocyte apoptosis is commonly observed in alcoholic liver disease. In this study, we investigated the effect of ginsenoside Rg1 (G-Rg1), an organic component of ginseng, on the alcohol-induced morphological and biophysical properties of hepatocytes. Human hepatocytes (HL-7702) were treated in vitro with alcohol and G-Rg1. The cell morphology was observed using scanning electron microscopy. Cell height, roughness, adhesion, and elastic modulus were detected using atomic force microscopy. We found that alcohol significantly induced hepatocyte apoptosis, whereas G-Rg1 attenuated the alcohol-induced hepatocyte damage. Scanning electron microscopy revealed that alcohol-induced significant morphological changes in hepatocytes, including decreased cell contraction, roundness, and pseudopods, whereas G-Rg1 inhibited these negative changes. Atomic force microscopy revealed that alcohol increased the cell height and decreased the adhesion and elastic modulus of hepatocytes. Following treatment with G-Rg1, the cell height, adhesion, and elastic modulus of alcohol-injured hepatocytes were all similar to those of normal cells. Thus, G-Rg1 can attenuate the alcohol-induced damage to hepatocytes by modulating the morphology and biomechanics of the cells. RESEARCH HIGHLIGHTS: In this study, the morphological characteristics of hepatocytes were observed using SEM. The changes in hepatocyte three-dimensional images and biomechanical action caused by alcohol and G-Rg1 were examined at the nanoscale using AFM under near-physiological conditions. Alcohol-induced hepatocytes showed abnormal morphology and biophysical properties. G-Rg1 attenuated the alcohol-induced damage to hepatocytes by modulating the morphology and biomechanics of the cells.

Detection and classification of hepatocytes and hepatoma cells using atomic force microscopy and machine learning algorithms

Hepatocellular carcinoma is a high-risk malignant tumor. Hepatoma cells are transformed from normal cells and have unique surface nanofeatures in addition to the characteristics of the original cells. In this paper, atomic force microscopy was used to extract the three-dimensional morphology and mechanical information of HL-7702 human hepatocytes and SMMC-7721 and HepG2 hepatoma cells in culture, such as the elastic modulus and viscoelasticity. The characteristics of different cells were compared and analyzed. Finally, the cell morphology and mechanics information were used for training machine learning algorithms. With the trained model, the detection of cells was realized. The classification accuracy was as high as 94.54%, and the area under the receiver operating characteristic (ROC) curve (AUC) was 0.99. Thus, hepatocytes and hepatoma cells were accurately identified and assessed. We also compared the classification effects of other machine learning algorithms, such as support vector machine and logistic regression. Our method extracts cellular nanofeatures directly from the surface of cells of unknown type for cell classification. Compared with microscope image-based analysis and other methods, this approach can avoid the misjudgment that may occur when different doctors have different levels of experience. Thus, the proposed method provides an objective basis for the early diagnosis of hepatocellular carcinoma. RESEARCH HIGHLIGHTS: The 3D appearance and mechanical characteristics of hepatocellular carcinoma cells are very similar to those of hepatocytes. Application of atomic force microscopy with machine learning algorithm. Collect the data set of nano-characteristic parameters of the cell. The machine learning algorithms is trained by data set, and its classification effect is better than that of a single nano-parameter.

Ultrastructural evidence of four types of lipofuscins in the melanomacrophagic centers in hepatocytes of zebrafish (Denio rerio)

Melanomacrophagic centers (MMCs) were studied in the hepatocytes of zebrafish using transmission electron microscope (TEM). The MMCs with irregular or amoeboid nucleus were located in the hepatocytes adjacent to the bile canaliculi. Several engulfed structures were present in the cytoplasm of MMCs. The most frequent observation was the presence of mitochondria, ranging in size from small to giant, with distorted shape and inconspicuous cristae. Occasionally the fragments of erythrocytes were found. The rough endoplasmic reticulum (rER) showed whirling around the mitochondria and lipid droplets, forming membrane-like structures. The damaged mitochondria were invaded by the lysosomes, and this was covered by a membrane led to the formation of lipofuscin. Four different types of lipofuscins were observed; namely, (1) granular with/without vacuoles of high electron-density, (2) homogenous surrounded by indistinct limiting membrane, (3) lamellated structures similar to inner matrix and cristae of mitochondria, and, (4) compound structure made by the combinations of first 3 types, (granular and homogenous, granular and lamellated, homogenous and lamellated). The present evidence suggests that MMCs in the hepatocytes of zebrafish perform continuous functions of removal of the damaged cellular organelles. The lipofuscin formation work in coordination with the cellular players of immune system and remove pathogens and maintain the internal homeostasis of cells.

Hepatic and Extrahepatic Sources and Manifestations in Endoplasmic Reticulum Storage Diseases

Alpha-1-antitrypsin (AAT) and fibrinogen are secretory acute phase reactant proteins. Circulating AAT and fibrinogen are synthesized exclusively in the liver. Mutations in the encoding genes result in conformational abnormalities of the two molecules that aggregate within the rough endoplasmic reticulum (RER) instead of being regularly exported. That results in AAT-deficiency (AATD) and in hereditary hypofibrinogenemia with hepatic storage (HHHS). The association of plasma deficiency and liver storage identifies a new group of pathologies: endoplasmic reticulum storage disease (ERSD).

Mettl14-Mediated m6A Modification Facilitates Liver Regeneration by Maintaining Endoplasmic Reticulum Homeostasis

BACKGROUND & AIMS

N6-methyladenosine (m6A), the most prevalent and dynamic posttranscriptional methylation modification of mammalian mRNA, is involved in various biological processes, but its role in liver regeneration has not been characterized.

METHODS

We first conducted transcriptome-wide m6A mRNA sequencing and characterized the expression pattern of m6A in regenerating mouse liver. Next, we generated hepatocyte-specific Mettl3- or Mettl14-deficient mice and investigated their role in liver regeneration. A series of biochemical experiments in vitro and in vivo was further performed to investigate potential mechanisms.

RESULTS

We identified an overwhelming proportion of m6A-modified genes with initially up-regulated and subsequently down-regulated m6A levels as liver regeneration progressed. Loss of Mettl14 but not of Mettl3 resulted in markedly disrupted liver regeneration, and Mettl14-ablated hepatocytes were arrested in the G1 phase of the cell cycle. Most strikingly, the Mettl14-ablated regenerating liver exhibited extensive parenchymal necrosis. mRNA transcripts, such as Hsp90b1, Erp29, Stt3a, P4hb, and Lman1, encoding proteins involved in polypeptide processing and the endoplasmic reticulum (ER) stress response, were m6A-hypomethylated, and their mRNA and protein levels were subsequently decreased, resulting in unresolved ER stress, hepatocyte death, and inhibited proliferation.

CONCLUSIONS

We demonstrate the essential role of Mettl14 in facilitating liver regeneration by modulating polypeptide-processing proteins in the ER in an m6A-dependent manner.

3D bioprinting of hepatocytes: core-shell structured co-cultures with fibroblasts for enhanced functionality

With the aim of understanding and recapitulating cellular interactions of hepatocytes in their physiological microenvironment and to generate an artificial 3D in vitro model, a co-culture system using 3D extrusion bioprinting was developed. A bioink based on alginate and methylcellulose (algMC) was first shown to be suitable for bioprinting of hepatocytes; the addition of Matrigel to algMC enhanced proliferation and morphology of them in monophasic scaffolds. Towards a more complex system that allows studying cellular interactions, we applied core-shell bioprinting to establish tailored 3D co-culture models for hepatocytes. The bioinks were specifically functionalized with natural matrix components (based on human plasma, fibrin or Matrigel) and used to co-print fibroblasts and hepatocytes in a spatially defined, coaxial manner. Fibroblasts acted as supportive cells for co-cultured hepatocytes, stimulating the expression of certain biomarkers of hepatocytes like albumin. Furthermore, matrix functionalization positively influenced both cell types in their respective compartments by enhancing their adhesion, viability, proliferation and function. In conclusion, we established a functional co-culture model with independently tunable compartments for different cell types via core-shell bioprinting. This provides the basis for more complex in vitro models allowing co-cultivation of hepatocytes with other liver-specific cell types to closely resemble the liver microenvironment.

Aging-Related Changes in the Ultrastructure of Hepatocytes and Cardiomyocytes of Elderly Mice Are Enhanced in ApoE-Deficient Animals

Biological aging is associated with various morphological and functional changes, yet the mechanisms of these phenomena remain unclear in many tissues and organs. Hyperlipidemia is among the factors putatively involved in the aging of the liver and heart. Here, we analyzed morphological, ultrastructural, and biochemical features in adult (7-month-old) and elderly (17-month-old) mice, and then compared age-related features between wild type (C57Bl/6 strain) and ApoE-deficient (transgenic ApoE^−/−) animals. Increased numbers of damaged mitochondria, lysosomes, and lipid depositions were observed in the hepatocytes of elderly animals. Importantly, these aging-related changes were significantly stronger in hepatocytes from ApoE-deficient animals. An increased number of damaged mitochondria was observed in the cardiomyocytes of elderly animals. However, the difference between wild type and ApoE-deficient mice was expressed in the larger size of mitochondria detected in the transgenic animals. Moreover, a few aging-related differences were noted between wild type and ApoE-deficient mice at the level of plasma biochemical markers. Levels of cholesterol and HDL increased in the plasma of elderly ApoE^−/− mice and were markedly higher than in the plasma of elderly wild type animals. On the other hand, the activity of alanine transaminase (ALT) decreased in the plasma of elderly ApoE^−/− mice and was markedly lower than in the plasma of elderly wild type animals.

Lysosomal SLC46A3 modulates hepatic cytosolic copper homeostasis

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes hepatic toxicity associated with prominent lipid accumulation in humans. Here, the authors report that the lysosomal copper transporter SLC46A3 is induced by TCDD and underlies the hepatic lipid accumulation in mice, potentially via effects on mitochondrial function. SLC46A3 was localized to the lysosome where it modulated intracellular copper levels. Forced expression of hepatic SLC46A3 resulted in decreased mitochondrial membrane potential and abnormal mitochondria morphology consistent with lower copper levels. SLC46A3 expression increased hepatic lipid accumulation similar to the known effects of TCDD exposure in mice and humans. The TCDD-induced hepatic triglyceride accumulation was significantly decreased in Slc46a3-/- mice and was more pronounced when these mice were fed a high-fat diet, as compared to wild-type mice. These data are consistent with a model where lysosomal SLC46A3 induction by TCDD leads to cytosolic copper deficiency resulting in mitochondrial dysfunction leading to lower lipid catabolism, thus linking copper status to mitochondrial function, lipid metabolism and TCDD-induced liver toxicity.

p62/SQSTM1-droplet serves as a platform for autophagosome formation and anti-oxidative stress response

Autophagy contributes to the selective degradation of liquid droplets, including the P-Granule, Ape1-complex and p62/SQSTM1-body, although the molecular mechanisms and physiological relevance of selective degradation remain unclear. In this report, we describe the properties of endogenous p62-bodies, the effect of autophagosome biogenesis on these bodies, and the in vivo significance of their turnover. p62-bodies are low-liquidity gels containing ubiquitin and core autophagy-related proteins. Multiple autophagosomes form on the p62-gels, and the interaction of autophagosome-localizing Atg8-proteins with p62 directs autophagosome formation toward the p62-gel. Keap1 also reversibly translocates to the p62-gels in a p62-binding dependent fashion to activate the transcription factor Nrf2. Mice deficient for Atg8-interaction-dependent selective autophagy show that impaired turnover of p62-gels leads to Nrf2 hyperactivation in vivo. These results indicate that p62-gels are not simple substrates for autophagy but serve as platforms for both autophagosome formation and anti-oxidative stress.

Perfluorooctanoic acid-induced cellular and subcellular alterations in fish hepatocytes

Liver perfluorooctanoic acid (PFOA) pathophysiology and related morphofunction disturbances were studied in common carp at the cellular and subcellular level and with box-counting fractal analysis of ultrathin sections to assess the effect of PFOA exposure on hepatocyte structure complexity and heterogeneity. Three experimental groups were investigated: unexposed; low exposure (200 ng L^-1 PFOA); high exposure (2 mg L^-1 PFOA). PFOA-exposed cells showed differences from controls at both tested concentrations, manifested mainly as cloudy swelling and reversible vacuolar degeneration. Subcellular modifications primarily involved mitochondria and secondarily endoplasmic reticulum, with evidence of increased subcellular turnover. The alterations were consistent with oxidative stress related pathophysiology. Fractal analysis discriminated exposed from unexposed fish and low from high PFOA exposure based on lacunarity and fractal dimension, respectively. The absence of irreversible organelle alterations and apoptosis/necrosis, along with the increase of cellular complexity, led to the conclusion that the patterns observed represented an adaptive recovery response.

The SARS-CoV-2 envelope and membrane proteins modulate maturation and retention of the spike protein, allowing assembly of virus-like particles

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a β-coronavirus, is the causative agent of the COVID-19 pandemic. Like for other coronaviruses, its particles are composed of four structural proteins: spike (S), envelope (E), membrane (M), and nucleoprotein (N) proteins. The involvement of each of these proteins and their interactions are critical for assembly and production of β-coronavirus particles. Here, we sought to characterize the interplay of SARS-CoV-2 structural proteins during the viral assembly process. By combining biochemical and imaging assays in infected versus transfected cells, we show that E and M regulate intracellular trafficking of S as well as its intracellular processing. Indeed, the imaging data reveal that S is relocalized at endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) or Golgi compartments upon coexpression of E or M, as observed in SARS-CoV-2-infected cells, which prevents syncytia formation. We show that a C-terminal retrieval motif in the cytoplasmic tail of S is required for its M-mediated retention in the ERGIC, whereas E induces S retention by modulating the cell secretory pathway. We also highlight that E and M induce a specific maturation of N-glycosylation of S, independently of the regulation of its localization, with a profile that is observed both in infected cells and in purified viral particles. Finally, we show that E, M, and N are required for optimal production of virus-like-particles. Altogether, these results highlight how E and M proteins may influence the properties of S proteins and promote the assembly of SARS-CoV-2 viral particles.

Biochemical and ultrastructural changes in kidney and liver of African Giant Rats (Cricetomysgambianus, Waterhouse, 1840) exposed to intraperitoneal sodium metavanadate (vanadium) intoxication

We studied the hepatic and renal impact of sodium metavanadate (SMV) exposure in African giant rats (AGR). Twelve male AGR were used and divided into two groups. The control group received sterile water while the SMV-exposed group received 3 mg/kg SMV intraperitoneally for 14 days. SMV exposed AGR groups showed significantly decreased activities of serum AST, ALT, ALP and creatinine concentration but increased blood urea nitrogen (BUN), albumin and globulin concentrations. Kidney ultrastructure examination revealed atrophy of the glomerular tuft, loss of podocytes, distortions of the endothelium and glomerular basement membrane. The liver sinusoids fenestration phenotypes were abnormal. Hepatocytes exhibited hypertrophy with uneven, crenated and dentate nuclei. SMV exposure induced activation of monocytes, as well as Kupffer and fibrous cells. Alterations in glomerular podocytes and cell-cell and cell matrix contact and inflammatory liver fibrosis are key events in progressive glomerular failure and hepatic damage due to SMV intoxication.

The effect of Ginsenoside Rg1 in hepatic ischemia reperfusion (I/R) injury ameliorates ischemia-reperfusion-induced liver injury by inhibiting apoptosis

Hepatic ischemia reperfusion (I/R) injury (HIRI) HIRI is a complex, multifactorial pathophysiological process and in liver surgery has been known to significantly affect disease prognosis, surgical success rates, and patient survival. Ginsenoside Rgl (Rgl) monomer is one of the main active ingredients of ginseng. Previous studies have demonstrated that Rgl exerts various pharmacological effects through several mechanisms including suppression of apoptosis-related proteins levels, downregulation of inflammatory mediators and as well as antioxidant, which effectively exerts an organ protective effect I/R-induced damage. However, the exact mechanisms of Rg1 on HIRI remain to be elucidated. In the present study, we investigated the protective effect of Rg1 on hepatic ischemia-reperfusion (I/R) injury (HIRI) and explored its underlying molecular mechanism. A rat warm I/R injury model in vivo and an oxygen-glucose deprivation/reperfusion (OGD/R)-treated BRL-3A cell model in vitro were established after pretreating with Rg1(20 mg/kg). The results showed that Rg1 reduced the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). TUNEL staining showed that pretreated with Rg1 inhibited the apoptosis rate compared with the I/R group. Moreover, pretreated with Rg1 significantly reduced the expression of Cyt-C, Caspase-9 and Caspase-3 to inhibit the cell apoptosis. Flow cytometry analysis showed the MMP in the I/R group was significantly increased, whereas pretreated with Rg1 effectively stabilized the MMP compared with the I/R group. in vitro, the proliferation of BRL-3A cells was significantly decreased by the OGD/R treatment, while Rg1 effectively reversed this phenomenon. In addition, western blotting showed that the increase of Cyt-C, Caspase-9 and Caspase-3 was inhibited by H2O2. These observations suggest that Rg1 exerts the protective effect by inhibiting the CypD protein-mediated mitochondrial apoptotic pathway.

HighVia-A Flexible Live-Cell High-Content Screening Pipeline to Assess Cellular Toxicity

High-content screening to monitor disease-modifying phenotypes upon small-molecule addition has become an essential component of many drug and target discovery platforms. One of the most common phenotypic approaches, especially in the field of oncology research, is the assessment of cell viability. However, frequently used viability readouts employing metabolic proxy assays based on homogeneous colorimetric/fluorescent reagents are one-dimensional, provide limited information, and can in many cases yield conflicting or difficult-to-interpret results, leading to misinterpretation of data and wasted resources.The resurgence of high-content, phenotypic screening has significantly improved the quality and breadth of cell viability data, which can be obtained at the very earliest stages of drug and target discovery. Here, we describe a relatively inexpensive, high-throughput, high-content, multiparametric, fluorescent imaging protocol using a live-cell method of three fluorescent probes (Hoechst, Yo-Pro-3, and annexin V), that is amenable to the addition of further fluorophores. The protocol enables the accurate description and profiling of multiple cell death mechanisms, including apoptosis and necrosis, as well as accurate determination of compound IC50, and has been validated on a range of high-content imagers and image analysis software. To validate the protocol, we have used a small library of approximately 200 narrow-spectrum kinase inhibitors and clinically approved drugs. This fully developed, easy-to-use pipeline has subsequently been implemented in several academic screening facilities, yielding fast, flexible, and rich cell viability data for a range of early-stage high-throughput drug and target discovery programs.

The ultrastructural characteristics of bile canaliculus in porcine liver donated after cardiac death and machine perfusion preservation

The effects of each type of machine perfusion preservation (MP) of liver grafts donated after cardiac death on the bile canaliculi of hepatocytes remain unclear. We analyzed the intracellular three-dimensional ultrastructure of the bile canaliculi and hepatocyte endomembrane systems in porcine liver grafts after warm ischemia followed by successive MP with modified University of Wisconsin gluconate solution. Transmission and osmium-maceration scanning electron microscopy revealed that lumen volume of the bile canaliculi decreased after warm ischemia. In liver grafts preserved by hypothermic MP condition, bile canaliculi tended to recover in terms of lumen volume, while their microvilli regressed. In contrast, midthermic MP condition preserved the functional form of the microvilli of the bile canaliculi. Machine perfusion preservation potentially restored the bile canaliculus lumen and alleviated the cessation of cellular endocrine processes due to warm ischemia. In addition, midthermic MP condition prevented the retraction of the microvilli of bile canaliculi, suggesting further mitigation of the damage of the bile canaliculi.

Stem cell-derived polarized hepatocytes

Human stem cell-derived hepatocyte-like cells (HLCs) offer an attractive platform to study liver biology. Despite their numerous advantages, HLCs lack critical in vivo characteristics, including cell polarity. Here, we report a stem cell differentiation protocol that uses transwell filters to generate columnar polarized HLCs with clearly defined basolateral and apical membranes separated by tight junctions. We show that polarized HLCs secrete cargo directionally: Albumin, urea, and lipoproteins are secreted basolaterally, whereas bile acids are secreted apically. Further, we show that enterically transmitted hepatitis E virus (HEV) progeny particles are secreted basolaterally as quasi-enveloped particles and apically as naked virions, recapitulating essential steps of the natural infectious cycle in vivo. We also provide proof-of-concept that polarized HLCs can be used for pharmacokinetic and drug-drug interaction studies. This novel system provides a powerful tool to study hepatocyte biology, disease mechanisms, genetic variation, and drug metabolism in a more physiologically relevant setting.

A Screen Using iPSC-Derived Hepatocytes Reveals NAD+ as a Potential Treatment for mtDNA Depletion Syndrome

Patients with mtDNA depletion syndrome 3 (MTDPS3) often die as children from liver failure caused by severe reduction in mtDNA content. The identification of treatments has been impeded by an inability to culture and manipulate MTDPS3 primary hepatocytes. Here we generated DGUOK-deficient hepatocyte-like cells using induced pluripotent stem cells (iPSCs) and used them to identify drugs that could improve mitochondrial ATP production and mitochondrial function. Nicotinamide adenine dinucleotide (NAD) was found to improve mitochondrial function in DGUOK-deficient hepatocyte-like cells by activating the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α). NAD treatment also improved ATP production in MTDPS3-null rats and in hepatocyte-like cells that were deficient in ribonucleoside-diphosphate reductase subunit M2B (RRM2B), suggesting that it could be broadly effective. Our studies reveal that DGUOK-deficient iPSC-derived hepatocytes recapitulate the pathophysiology of MTDPS3 in culture and can be used to identify therapeutics for mtDNA depletion syndromes.

Deciphering host lysosome-mediated elimination of Plasmodium berghei liver stage parasites

Liver stage Plasmodium parasites reside in a parasitophorous vacuole (PV) that associates with lysosomes. It has previously been shown that these organelles can have beneficial as well as harmful effects on the parasite. Yet it is not clear how the association of lysosomes with the parasite is controlled and how interactions with these organelles lead to the antagonistic outcomes. In this study we used advanced imaging techniques to characterize lysosomal interactions with the PV. In host cells harboring successfully developing parasites we observed that these interaction events reach an equilibrium at the PV membrane (PVM). In a population of arrested parasites, this equilibrium appeared to shift towards a strongly increased lysosomal fusion with the PVM witnessed by strong PVM labeling with the lysosomal marker protein LAMP1. This was followed by acidification of the PV and elimination of the parasite. To systematically investigate elimination of arrested parasites, we generated transgenic parasites that express the photosensitizer KillerRed, which leads to parasite killing after activation. Our work provides insights in cellular details of intracellular killing and lysosomal elimination of Plasmodium parasites independent of cells of the immune system.

Development of three-dimensional (3D) spheroid cultures of the continuous rainbow trout liver cell line RTL-W1

In vitro experimental systems based on continuous piscine cell lines can be used as an alternative to animal tests for obtaining qualitative and quantitative information on the possible fate and effect of chemicals in fish. However, their capability to reproduce complex metabolic processes and toxic responses as they occur in vivo is limited due to the lack of organ-specific tissue architecture and functions. Here we introduce a three-dimensional (3D) in vitro experimental system based on spheroidal aggregate cultures (spheroids) of the continuous rainbow trout liver cell line RTL-W1 and provide a first description of their structural and functional properties including growth, viability/longevity, metabolic activity, ultrastructure and cytochrome P450 1A (CYP1A) expression determined by bright-field, multi-photon fluorescence and transmission electron microscopy as well as RT-qPCR analysis. Our results show that RTL-W1 cells in 3D spheroids (ø ~ 150 µm) (including those in the interior) were viable, metabolically active and had higher basal and β-naphthoflavone-induced CYP1A expression levels than conventional 2D cell cultures. Furthermore, they displayed ultrastructural characteristics similar to differentiated hepatocytes. The available evidence suggests that 3D RTL-W1 spheroids may have enhanced hepatotypic functions and be a superior in vitro model to assess hepatic biotransformation, bioaccumulation and chronic toxicity compared to conventional cell monolayer cultures.

A High-Calorie Diet Aggravates Mitochondrial Dysfunction and Triggers Severe Liver Damage in Wilson Disease Rats

BACKGROUND & AIMS

In Wilson disease, ATP7B mutations impair copper excretion into bile. Hepatic copper accumulation may induce mild to moderate chronic liver damage or even acute liver failure. Etiologic factors for this heterogeneous phenotype remain enigmatic. Liver steatosis is a frequent finding in Wilson disease patients, suggesting that impaired copper homeostasis is linked with liver steatosis. Hepatic mitochondrial function is affected negatively both by copper overload and steatosis. Therefore, we addressed the question of whether a steatosis-promoting high-calorie diet aggravates liver damage in Wilson disease via amplified mitochondrial damage.

METHODS

Control Atp7b+/- and Wilson disease Atp7b-/- rats were fed either a high-calorie diet (HCD) or a normal diet. Copper chelation using the high-affinity peptide methanobactin was used in HCD-fed Atp7b-/- rats to test for therapeutic reversal of mitochondrial copper damage.

RESULTS

In comparison with a normal diet, HCD feeding of Atp7b-/- rats resulted in a markedly earlier onset of clinically apparent hepatic injury. Strongly increased mitochondrial copper accumulation was observed in HCD-fed Atp7b-/- rats, correlating with severe liver injury. Mitochondria presented with massive structural damage, increased H2O2 emergence, and dysfunctional adenosine triphosphate production. Hepatocellular injury presumably was augmented as a result of oxidative stress. Reduction of mitochondrial copper by methanobactin significantly reduced mitochondrial impairment and ameliorated liver damage.

CONCLUSIONS

A high-calorie diet severely aggravates hepatic mitochondrial and hepatocellular damage in Wilson disease rats, causing an earlier onset of the disease and enhanced disease progression.

Assessment of exogenous melatonin action on mouse liver cells after exposure to soman

Melatonin is a hormone with many different biological activities and therefore seems to be an important factor reducing the harmful effects caused by toxic organophosphorus compounds. In this study, we attempted to evaluate the protective effect of melatonin on liver cells of mice challenged with chemical warfare agent-soman. The study was conducted at the level of ultrastructural and biochemical changes (analysis of the activity of model lysosomal enzymes and assessment of the level of lipid peroxidation). Significant biochemical and ultrastructural changes were found in the studied mouse hepatocytes after administration of soman alone, and soman in combination with melatonin, and the scope of the disclosed changes was dependent on the time of action of the examined factors. Melatonin has shown protective action, shielding liver cells from toxic effects of soman, which may result from its antioxidant properties and stimulation of the lysosomal compartment, the system coordinating the isolation and removal of cell-threatening processes.

GW0742 (PPAR-beta agonist) attenuates hepatic endoplasmic reticulum stress by improving hepatic energy metabolism in high-fat diet fed mice

Endoplasmic reticulum (ER) stress and hepatic steatosis are intertwined with insulin resistance. PPARs are at the crossroads of these pathways. This study aimed to investigate the effects of GW0742 (PPAR-beta agonist) on hepatic energy metabolism and ER stress in a murine diet-induced obesity model. HF diet caused overweight, hyperinsulinemia, hepatic inflammation (increased NF-kB, TNF-alpha, and IL-6 protein expression) and favored hepatic lipogenesis, leading to ER stress, with ultrastructural and molecular alterations, ending up in proapoptotic stimulus. GW0742 rescued the overweight and the glucose tolerance, tackled hepatic inflammation and favored hepatic beta-oxidation over lipogenesis. These results comply with ER ultrastructure improvement, reducing ER stress and apoptosis in treated animals. Our results indicate that the PPAR-beta/delta activation alleviated the ER stress by improving the insulin sensitivity and maximizing the hepatic energy metabolism with a shift towards beta-oxidation. PPAR-beta/delta activation could be an essential tool to avoid the NAFLD progression and other obesity constraints.

A "Lamellar structure" contributes to autophagosome biogenesis and mitophagy in zebrafish hepatocytes

Despite many studies being conducted over the past few decades, the origin of autophagosomal membranes remains unclear. The present study aimed to uncover the formation process of autophagosomal membranes in hepatocytes of zebrafish (Danio rerio), a model organism in medical science. Immunohistochemistry of zebrafish hepatocytes indicated that light chain 3-like protein 2 (LC3-II) is highly active in some hepatocytes, but poorly expressed in others. Under transmission electron microscopy, the amount of autophagosomes (APs) varied in different hepatocytes. When the endoplasmic reticulum (ER) is dispersed in the cytoplasm, few isolation membranes (IMs) and APs were observed. Subsequently, when the ER assembles into a particular "lamellar structure" (LS), IMs arise from it and extend to enwrap the mitochondria. With further aggregation of the ER, the LS developed into an over twenty-layered structure, and mitophagy was more obvious in the hepatocytes and cavities appeared in mitochondria. Finally, most ERs were assembled into several LSs. At this point, mitophagy was most active in the hepatocytes. Thereafter, glycogen and lipid droplet increased gradually, while the LS degenerated and ER scatter increased. Then, the glycogen and lipid droplets dominated the hepatocellular cytoplasm. After suppressing the formation of autophagosomes using 3-Methyladenine (3-MA), the LS could no longer be visualized in the hepatocellular cytoplasm, and mitophagy decreased drastically. Taken together, the results suggested that this LS in the hepatocytes of zebrafish, might be another manifestation of a pre-autophagosomal structure in zebrafish liver, analogous to the omegasome in yeast or the ER-IM complex in mammalian cell lines. Furthermore, selective mitophagy and consequent cyclic utilization of its products were probably relevant to dynamic cycle of the hepatocellular cytoplasm.

Heat shock protein 72 regulates hepatic lipid accumulation

Induction of the chaperone heat shock protein 72 (HSP72) through heat treatment (HT), exercise, or overexpression improves glucose tolerance and mitochondrial function in skeletal muscle. Less is known about HSP72 function in the liver where lipid accumulation can result in insulin resistance and nonalcoholic fatty liver disease (NAFLD). The purpose of this study was 1) to determine whether weekly in vivo HT induces hepatic HSP72 and improves glucose tolerance in rats fed a high-fat diet (HFD) and 2) to determine the ability of HSP72 to protect against lipid accumulation and mitochondrial dysfunction in primary hepatocytes. Male Wistar rats were fed an HFD for 15 wk and were given weekly HT (41°C, 20 min) or sham treatments (37°C, 20 min) for the final 7 wk. Glucose tolerance and insulin sensitivity were assessed, along with HSP72 induction and triglyceride storage, in the skeletal muscle and liver. The effect of an acute loss of HSP72 in primary hepatocytes was examined via siRNA. Weekly in vivo HT improved glucose tolerance, elevated muscle and hepatic HSP72 protein content, and reduced muscle triglyceride storage. In primary hepatocytes, mitochondrial morphology was changed, and fatty acid oxidation was reduced in small interfering HSP72 (siHSP72)-treated hepatocytes. Lipid accumulation following palmitate treatment was increased in siHSP72-treated hepatocytes. These data suggest that HT may improve systemic metabolism via induction of hepatic HSP72. Additionally, acute loss of HSP72 in primary hepatocytes impacts mitochondrial health as well as fat oxidation and storage. These findings suggest therapies targeting HSP72 in the liver may prevent NAFLD.

Compound Ammonium Glycyrrhizin Protects Hepatocytes from Injury Induced by Lipopolysaccharide/Florfenicol through a Mitochondrial Pathway

Florfenicol (FFC), a widely used drug for chicken diseases, can aggravate lipopolysaccharide (LPS) damage to the liver. For this condition, natural or synthetic products displaying strong antioxidant capacity are expected to prevent LPS/FFC from inducing liver injury, so in our study, the compound ammonium glycyrrhizin (CAG) is used as the protective drug to decrease the injury to liver. The research aims to illustrate the underlying mechanism of combining LPS with FFC-induced liver injury and the protective role of CAG by using primary chicken hepatocytes as an in vitro model. The results show that LPS/FFC induced cell apoptosis and CAG protected hepatocytes from injury. The permeability of the cell membrane is elevated by LPS/FFC, leading to the efflux of enzymes (ALT, AST). Flow cytometry analysis indicates that LPS/FFC treatment increased the apoptosis rate significantly. Furthermore, with the up-regulation of apoptosis genes bax, cytochrome c and the down-regulation of bcl-2, caspase-3 and caspase-9 are activated at the gene level. LPS/FFC-induced mitochondrial damage is accompanied by a significant decrease in mitochondrial membrane potential (MMP) and severe mitochondrial damage. However, CAG improves the situation for the purpose of protecting the liver. In conclusion, it is speculated that LPS/FFC induces severe liver injury through apoptosis and the CAG protects hepatocytes from injury via the mitochondria-mediated apoptosis pathway.

Detection of nanocarrier potentiation on drug induced phospholipidosis in cultured cells and primary hepatocyte spheroids by high content imaging and analysis

Considerable effort has been made to develop nanocarriers for controlled drug delivery over the last decade, while it remains unclear how the strength of adverse drug effect will be altered when a drug is loaded on the nanocarrier. Drug-induced phospholipidosis (DIP) is characterized with excessive accumulation of phospholipids in cells and is common for cationic amphiphilic drugs (CAD). Previously, we have reported that PEGylated graphene oxide (PEG-GO) loaded with several CAD can potentiate DIP. In current study, we extended our study on newly identified phospholipidosis (PLD) inducers that had been identified from the Library of Pharmacologically Active Compounds (LOPAC), to investigate if PEO-GO loaded with these CAD can alter DIP. Twenty-two CAD were respectively loaded on PEG-GO and incubated with RAW264.7, a macrophage cell line. The results showed that when a CAD was loaded on PEG-GO, its strength of PLD induction can be enhanced, unchanged or attenuated. PEG-GO loaded with Ifenprodil exhibited the highest PEG-GO potentiation effect compared to Ifenprodil treatment alone in RAW264.7 cells, and this effect was confirmed in human hepatocellular carcinoma HepG2, another cell line model for PLD induction. Primary hepatocyte culture and spheroids mimicking in vivo conditions were used to further validate nanocarrier potentiation on DIP by Ifenprodil. Stronger phospholipid accumulation was found in PEG-GO/Ifenprodil treated hepatocytes or spheroids than Ifenprodil treatment alone. Therefore, evidences were provided by us that nanocarriers may increase the adverse drug effects and guidance by regulatory agencies need to be drafted for the safe use of nanotechnology in drug delivery.

[Changes in autophagy during maturation and differentiation of Hepa1-6 cells induced by all-trans retinoic acid]

OBJECTIVE

To investigate the effects of different concentrations of all-trans retinoic acid (ATRA) on the maturation, differentiation and autophagy of Hepa1-6 cells.

MONTHOD

Hepa1-6 cells were treated with 0.1, 1, and 10 µmol/L ATRA, and the changes in the expressions of hepatic specific markers were detected using real-time PCR and Western blotting. Indocyanine green (ICG) and periodic acid-schiff (PAS) staining was used to assess the functional maturation of Hepa1-6 cells, and the cell-cell junction and autophagy were observed under transmission electron microscopy to determine the optimal concentration of ATRA for treatment. The expressions of autophagy-related markers in the cells were detected using Western blotting, and confocal microscopy was used to observe the autophagic flow in the cells transfected with ptfLC3 plasmid.

RESULTS

Compared with the control cells, the hepatocytes treated with ATRA showed a concentration-dependent decrease in AFP expression and increase in the expressions of ALB, CK18, TAT and ApoB. ICG and PAS staining revealed significantly increased number of positive cells after ATRA treatment. Following ATRA treatment, the cells exhibited obviously increased tight junctions, cytoskeleton and number of autophagosomes under transmission electron microscopy. ATRA treatment resulted in significantly increased the expressions of autophagy-related markers LC3-II, Beclin-1, RAB7 and P62 and also an increased ratio of LC3-II/LC3-I(P<0.05). Confocal microscopy revealed obviously increased green and red spots in the cells after ATRA treatment.

CONCLUSION

ATRA can induce the maturation and differentiation and enhance the level of autophagy in Hepa1-6 cells.

Long-term effects of low-dose mouse liver irradiation involve ultrastructural and biochemical changes in hepatocytes that depend on lipid metabolism

The aim of the study was to investigate long-term effects of radiation on the (ultra)structure and function of the liver in mice. The experiments were conducted on wild-type C57BL/6J and apolipoprotein E knock-out (ApoE^-/-) male mice which received a single dose (2 or 8 Gy) of X-rays to the heart with simultaneous exposure of liver to low doses (no more than 30 and 120 mGy, respectively). Livers were collected for analysis 60 weeks after irradiation and used for morphological, ultrastructural, and biochemical studies. The results show increased damage to mitochondrial ultrastructure and lipid deposition in hepatocytes of irradiated animals as compared to non-irradiated controls. Stronger radiation-related effects were noted in ApoE^-/- mice than wild-type animals. In contrast, radiation-related changes in the activity of lysosomal hydrolases, including acid phosphatase, β-glucuronidase, N-acetyl-β-D-hexosaminidase, β-galactosidase, and α-glucosidase, were observed in wild type but not in ApoE-deficient mice, which together with ultrastructural picture suggests a higher activity of autophagy in ApoE-proficient animals. Irradiation caused a reduction of plasma markers of liver damage in wild-type mice, while an increased level of hepatic lipase was observed in plasma of ApoE-deficient mice, which collectively indicates a higher resistance of hepatocytes from ApoE-proficient animals to radiation-mediated damage. In conclusion, liver dysfunctions were observed as late effects of irradiation with an apparent association with malfunction of lipid metabolism.

Adhesion and Function of Rat Liver Cells Adherent to Silk Fibroin/Collagen Blend Films

Collagen is often used in bioartificial livers as a biomimetic coating to promote liver cell adhesion and differentiation. Animal proteins are expensive and expose the host to risks of cross-species infection due to contamination with prions. Silk fibroin (SF) is a biocompatible protein produced by Bombyx mori silk worms and possibly an alternative to collagen. We prepared SF-collagen blend films with different SF content adherent to the bottom of standard tissue culture dishes, and characterized their surface morphology by SEM, their wettability and examined them for their capacity to support rat liver cell adhesion and metabolism. Cell metabolism was characterized by estimating the rate at which cells eliminated ammonia and synthesized urea for up to 48h of culture. SF-containing films were smooth, clear and more wettable than collagen. Cells readily adhered, formed junctions and small size aggregates on all films. As many cells adhered on SF as on collagen films. Cell adhesion to high collagen content blend films could not be reliably estimated because cells dwelt in the large cavities in the film. The effect of SF on cell metabolism differed with the investigated metabolic pathway. However, cells on SF-containing films eliminated ammonia and synthesized urea at rates generally comparable to, for urea synthesis at times higher than, that of cells on collagen. These results suggest that silk fibroin is a suitable substratum for liver cell attachment and culture, and a potential alternative to collagen as a biomimetic coating.

Experimental study of the liver ultrastructure in the presence of infection with herpes simplex virus 1

OBJECTIVE

Introduction: Understanding of HSV-1liver infection pathogenesis is of great scientific, social and economic significance, since this is one of the main latent infections in population. However reactivation of this infection remains understudied. The aim: This experimental research aimed at studying the ultrastructure changes occurring in the liver in the presence of HSV-1infection.

PATIENTS AND METHODS

Materials and methods: Experiments were conducted on 12 BALB/c line mice weighing 18-20 g. They were divided into 2 groups: experimental, and control. Experimental animals were infected with the attenuated HSV-1. On day 40 the animals were withdrawn from the experiment by decapitation. Liver fragments were excised and studied ultramicroscopically.

RESULTS

Results: Liver disorders were represented by the focal damage of hepatic lobuli cells. Ultrastructure changes were found both in the microvascular endothelium and hepatocytes. The vascular disorders included swelling of endotheliocytes, their demise and desquamation into the lumen, disruption of the basal lamina integrity and diapedesis of blood cells into the subendothelial space. Finding virions in the endotheliocytes allowed to explain the possible pathway of the infection into the interstitium and hepatocytes via systemic circulation from the primary source of infection. Electron microscopy has not revealed any virions in hepatocytes, with only the following changes: significant cytosole density of the osmiophylic granules, lisosomes and lamellar bodies found. These were considered to be the consequence of the infectious process. Findings of the experimental study enable understanding of the causal relationship between the acute infection and liver damage.

CONCLUSION

Conclusions: Ultrastructure changes in the liver of mice infected with HSV-1 were focal, and more rarely diffuse in nature. Non-specific cytopathological changes (swelling of the cytoplasm and reduction of the endoplasmatic reticulum, and mitochondria) were found both in the endotheliocytes of the sinusoid capillaries and hepatocytes. Endotheliocytes of the sinusoid liver capillaries in mice infected with HSV-1 lose their barrier function, which leads to direct and indirect damage of hepatocytes and development of dystrophic changes in the liver.

Cytotoxicity of silver and copper nanoparticles on rainbow trout (Oncorhynchus mykiss) hepatocytes

Nanoparticles are commonly used in the industry and are present in consumer goods; therefore, evaluation of their potential toxicity is necessary. The aim of the present study was to assess the cytotoxic effects of the nanoparticles of silver (AgNPs) at the concentration of 1.5 mg L^-1 and copper (CuNPs) at 0.15 mg L^-1 on rainbow trout (Oncorhynchus mykiss) hepatocytes after 28 days of exposure. Histological analysis revealed dilated sinusoids, shrunken hepatocytes, nuclear necrosis, and increased number of Kupffer cells in the liver of fish exposed to nanoparticles. The lowest hepatocyte proliferation index was observed in fish treated with AgNPs. Ultrastructural studies revealed mitochondrial edema and cristolysis, dilated and loosened endoplasmic reticulum, cytoplasm vacuolation, accumulation of lipid droplets, glycogen depletion, and formation of myelin-like bodies. The results also revealed that the liver of fish exposed to copper nanoparticles showed higher regenerative potential indicated by higher proliferation index, more abundant glycogen, and more numerous Kupffer cells compared to the fish treated with silver nanoparticles.

Testosterone-induced modulation of peroxisomal morphology and peroxisome-related gene expression in brown trout (Salmo trutta f. fario) primary hepatocytes

Disruption of androgenic signaling has been linked to possible cross-modulation with other hormone-mediated pathways. Therefore, our objective was to explore effects caused by testosterone - T (1, 10 and 50μM) in peroxisomal signaling of brown trout hepatocytes. To study the underlying paths involved, several co-exposure conditions were tested, with flutamide - F (anti-androgen) and ICI 182,780 - ICI (anti-estrogen). Molecular and morphological approaches were both evaluated. Peroxisome proliferator-activated receptor alpha (PPARα), catalase and urate oxidase were the selected targets for gene expression analysis. The vitellogenin A gene was also included as a biomarker of estrogenicity. Peroxisome relative volumes were estimated by immunofluorescence, and transmission electron microscopy was used for qualitative morphological control. The single exposures of T caused a significant down-regulation of urate oxidase (10 and 50μM) and a general up-regulation of vitellogenin. A significant reduction of peroxisome relative volumes and smaller peroxisome profiles were observed at 50μM. Co-administration of T and ICI reversed the morphological modifications and vitellogenin levels. The simultaneous exposure of T and F caused a significant and concentration-dependent diminishing in vitellogenin expression. Together, the findings suggest that in the tested model, T acted via both androgen and estrogen receptors to shape the peroxisomal related targets.

Ultrastructural Characterization of Zika Virus Replication Factories

A global concern has emerged with the pandemic spread of Zika virus (ZIKV) infections that can cause severe neurological symptoms in adults and newborns. ZIKV is a positive-strand RNA virus replicating in virus-induced membranous replication factories (RFs). Here we used various imaging techniques to investigate the ultrastructural details of ZIKV RFs and their relationship with host cell organelles. Analyses of human hepatic cells and neural progenitor cells infected with ZIKV revealed endoplasmic reticulum (ER) membrane invaginations containing pore-like openings toward the cytosol, reminiscent to RFs in Dengue virus-infected cells. Both the MR766 African strain and the H/PF/2013 Asian strain, the latter linked to neurological diseases, induce RFs of similar architecture. Importantly, ZIKV infection causes a drastic reorganization of microtubules and intermediate filaments forming cage-like structures surrounding the viral RF. Consistently, ZIKV replication is suppressed by cytoskeleton-targeting drugs. Thus, ZIKV RFs are tightly linked to rearrangements of the host cell cytoskeleton.

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ZIKV induces ER membrane invaginations similar to Dengue virus

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ZIKV induces profound alterations of the cytoskeleton

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Microtubules and intermediate filaments surround the ZIKV replication factory

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ZIKV replication is sensitive to cytoskeleton-targeting drugs

Hypothermic machine perfusion with metformin-University of Wisconsin solution for ex vivo preservation of standard and marginal liver grafts in a rat model

AIM

To compare the effect of University of Wisconsin (UW) solution with or without metformin, an AMP-activated protein kinase (AMPK) activator, for preserving standard and marginal liver grafts of young and aged rats ex vivo by hypothermic machine perfusion (HMP).

METHODS

Eighteen young (4 mo old) and 18 aged (17 mo old) healthy male SD rats were selected and randomly divided into three groups: control group, UW solution perfusion group (UWP), and UW solution with metformin perfusion group (MUWP). Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), interleukin-18 (IL-18), and tumor necrosis factor-alpha (TNF-α) in the perfused liquid were tested. The expression levels of AMPK and endothelial nitric oxide synthase (eNOS) in liver sinusoidal endothelial cells were also examined. Additionally, microscopic evaluation of the harvested perfused liver tissue samples was done.

RESULTS

AST, ALT, LDH, IL-18 and TNF-α levels in the young and aged liver-perfused liquid were, respectively, significantly lower in the MUWP group than in the UWP group (P < 0.05), but no significant differences were found between the young and aged MUWP groups. Metformin increased the expression of AMPK and eNOS protein levels, and promoted the extracellular release of nitric oxide through activation of the AMPK-eNOS mediated pathway. Histological examination revealed that in the MUWP group, the extent of liver cells and tissue damage was significantly reduced compared with the UWP group.

CONCLUSION

The addition of metformin to the UW preservative solution for ex vivo HMP can reduce rat liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats.

The ultrastructural characteristics of porcine hepatocytes donated after cardiac death and preserved with warm machine perfusion preservation

The effects of warm machine perfusion preservation of liver grafts donated after cardiac death on the intracellular three-dimensional ultrastructure of the organelles in hepatocytes remain unclear. Here we analyzed comparatively the ultrastructure of the endomembrane systems in porcine hepatocytes under warm ischemia and successive hypothermic and midthermic machine perfusion preservation, a type of the warm machine perfusion. Porcine liver grafts which had a warm ischemia time of 60 minutes were perfused for 4 hours with modified University of Wisconsin gluconate solution. Group A grafts were preserved with hypothermic machine perfusion preservation at 8°C constantly for 4 hours. Group B grafts were preserved with rewarming up to 22°C by warm machine perfusion preservation for 4 hours. An analysis of hepatocytes after 60 minutes of warm ischemia by scanning electron microscope revealed the appearance of abnormal vacuoles and invagination of mitochondria. In the hepatocytes preserved by subsequent hypothermic machine perfusion preservation, strongly swollen mitochondria were observed. In contrast, the warm machine perfusion preservation could preserve the functional appearance of mitochondria in hepatocytes. Furthermore, abundant vacuoles and membranous structures sequestrating cellular organelles like autophagic vacuoles were frequently observed in hepatocytes after warm machine perfusion preservation. In conclusion, the ultrastructure of the endomembrane systems in the hepatocytes of liver grafts changed in accordance with the temperature conditions of machine perfusion preservation. In addition, temperature condition of the machine perfusion preservation may also affect the condition of the hepatic graft attributed to autophagy systems, and consequently alleviate the damage of the hepatocytes.

Pathological alterations in liver injury following congestive heart failure induced by volume overload in rats

Heart failure has emerged as a disease with significant public health implications. Following progression of heart failure, heart and liver dysfunction are frequently combined in hospitalized patients leading to increased morbidity and mortality. Here, we investigated the underlying pathological alterations in liver injury following heart failure. Heart failure was induced using a modified infrarenal aortocaval fistula (ACF) in male Wistar rats. Sham operated and ACF rats were compared for their morphometric and hemodynamic data, for histopathological and ultrastructural changes in the liver as well as differences in the expression of apoptotic factors. ACF-induced heart failure is associated with light microscopic signs of apparent congestion of blood vessels, increased apoptosis and breakdown of hepatocytes and inflammatory cell inifltration were observed. The glycogen content depletion associated with the increased hepatic fibrosis, lipid globule formation was observed in ACF rats. Moreover, cytoplasmic organelles are no longer distinguishable in many ACF hepatocytes with degenerated fragmented rough endoplasmic reticulum, shrunken mitochondria and heavy cytoplasm vacuolization. ACF is associated with the upregulation of the hepatic TUNEL-positive cells and proapoptotic factor Bax protein concomitant with the mitochondrial leakage of cytochrome C into the cell cytoplasm and the transfer of activated caspase 3 from the cytoplasm into the nucleus indicating intrinsic apoptotic events. Taken together, the results demonstrate that ACF-induced congestive heart failure causes liver injury which results in hepatocellular apoptotic cell death mediated by the intrinsic pathway of mitochondrial cytochrome C leakage and subsequent transfer of activated caspase 3 into to the nucleus to initiate overt DNA fragmentation and cell death.

Plasma metabolomics study of the hepatoprotective effect of glycyrrhetinic acid on realgar-induced sub-chronic hepatotoxicity in mice via 1H NMR analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar, a type of mineral drug that contains arsenic, is concurrently used with Glycyrrhizae Radx et Rhizoma to reduce its toxicity in many Chinese herbal formulations. Glycyrrhetinic acid (GA) is the bioactive ingredient in Glycyrrhizae Radx et Rhizoma. In this study, the protective effects of GA on realgar-induced hepatotoxicity was investigated using ¹H nuclear magnetic resonance (¹H NMR)-based metabolomic approaches.

MATERIALS AND METHODS

Mice were divided into control, GA, realgar, and GA and realgar co-administration groups. Their plasma samples were used for a metabolomics study.

RESULTS

GA can protect the mice against realgar-induced hepatotoxicity to some extent by relieving alterations in the clinical biochemical parameters and the damage to hepatocytes. Metabolic profiling via principal components analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) indicated that the metabolic perturbation caused by realgar was reduced by GA. Six metabolites, including 3-hydroxybutyrate (3-HB), very low density/low density lipoprotein (VLDL/LDL), N-acetylglycoprotein (NAc), lactate, choline and D-glucose, were considered as potential biomarkers that are involved in the toxicity reduction effect of GA on realgar-induced hepatotoxicity. The correlation analysis showed that these potential biomarkers were all positively correlated with ALT and AST activities (correlation coefficient > 0.5). Lipid and energy metabolism pathways were found to be primarily associated with the hepatoprotective effect of GA.

CONCLUSIONS

GA has an effective protection function by regulating the lipid and energy metabolism to liver injuries that are induced by realgar.

Instant Hepatic Differentiation of Human Embryonic Stem Cells Using Activin a and a Deleted Variant of HGF

Human embryonic stem (hES) cells have the ability to differentiate into a variety of different cell lineages and potentially provide a source of differentiated cells for many therapeutic uses. Here we investigated an efficient method of hepatic differentiation from hES cells. A human ES cell line, KhES-1, was used and maintained by a nonfeeder method. KhES-1 cells were cultured for 5 days in the presence of human activin A (50 ng/ml) and then treated with a deleted variant of hepatocyte growth factor (dHGF) at 0, 100, or 500 ng/ml for 7 days. The resultant cells were biologically analyzed. The expression of the endodermal genes SOX17 and FOXA2 increased in KhES-1 cells after activin A treatment. In contrast, Oct4, a self-renewal undifferentiated marker, decreased in a time-dependent manner in KhES-1 cells. Following a 7-day treatment of the resultant cells with dHGF, especially at 500 ng/ml, KhES-1 cells showed an expression of the hepatic makers albumin, AFP, and CK18. Transitional electron microscopy showed well-developed glycogen rosettes and a gap junction in KhES-1 cells treated with 500 ng/ml of dHGF. We developed an efficient method to differentiate KhES-1 cells into hepatocyte-like cells in vitro using 50 ng/ml of activin A and 500 ng/ml of dHGF.

Long-Term Maintenance of Liver-Specific Functions in Cultured ES Cell-Derived Hepatocytes with Hyaluronan Sponge

This study investigated the three-dimensional culture of hepatocytes differentiated from mouse embryonic stem (ES) cells with a porous hyaluronan (HA) sponge support. Hepatocytes were immobilized within the pores of the support. Spheroids could be observed within the support, each containing between 20 and 50 hepatocytes. To examine the liver-specific functions of the hepatocytes in the culture, the levels of albumin secreted into the medium were analyzed. The secretion of albumin was stable over the course of 32 days, longer than that in both conventional monolayer and collagen sponge cultures. To elucidate further the liver-specific functions of hepatocytes embedded in the HA sponge, metabolic activities of the hepatocytes were examined for their ability to eliminate ammonia from culture media and the synthesis of urea nitrogen. While rates of ammonia removal and urea nitrogen synthesis were similar to those in both conventional monolayer and in collagen sponge cultures, these functions were maintained for longer duration in cells embedded in the HA sponge. These results demonstrate that the porous HA sponge is an effective support for the in vitro culture of ES-derived hepatocytes used for both basic and applied studies for cell transplantation.

Inhibitory effect of oxymatrine on hepatocyte apoptosis via TLR4/PI3K/Akt/GSK-3β signaling pathway

AIM

To evaluate the effect of oxymatrine (OMT) on hepatocyte apoptosis in rats with lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver failure (ALF).

METHODS

LPS/D-GalN was used to establish a model of ALF in rats. To evaluate the effect of OMT, we assessed apoptosis by transmission electron microscopy, and the pathological changes in the liver by light microscopy with hematoxylin and eosin staining. An automated biochemical analyzer was used to measure serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Enzyme-linked immunosorbent assay was used to determine the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β. Western blotting was used to detect protein levels in liver tissues. Streptavidin peroxidase immunohistochemistry was used to observe expression of Toll-like receptor (TLR)4, active caspase-3, Bax and Bcl-2.

RESULTS

All rats in the normal control and OMT-pretreated groups survived. The mortality rate in the model group was 30%. OMT preconditioning down-regulated apoptosis of hepatocytes and ameliorated pathological changes in liver tissue. The levels of AST, ALT, TNF-α and IL-1β in the model group increased significantly, and were significantly reduced by OMT pretreatment. OMT pretreatment down-regulated expression of TLR4 and active caspase-3 and the Bax/Bcl-2 ratio, and up-regulated expression of P-Akt^Ser473 (Akt phosphorylated at serine 473) and P-GSK3β^Ser9 (glycogen synthase kinase 3β phosphorylated at serine 9) induced by LPS/D-GalN.

CONCLUSION

OMT inhibits hepatocyte apoptosis by suppressing the TLR4/PI3K/Akt/GSK-3β signaling pathway, which suggests that OMT is an effective candidate for ameliorating acute liver failure.

Hepatotoxicity and metabolic effects of cellular extract of cyanobacterium Radiocystis fernandoi containing microcystins RR and YR on neotropical fish (Hoplias malabaricus)

The toxicological effect of cellular extract of cyanobacterium Radiocystis fernandoi strain R28 containing RR and YR microcystins was analyzed in the fish Hoplias malabaricus with emphasis on the liver structure and energetic metabolism, after short-term exposure. Fish were intraperitoneally (i.p.) injected with 100 μg of equivalent MC-LR kg^-1 body mass containing in the cellular extract of R. fernandoi strain R28. Twelve and 96 h post-injection, the plasma, liver and white muscle were sampled for biochemical analyses and liver was also sampled for morphological analyses. After i.p. injection, the activity of acid phosphatase (ACP), alanine aminotransferase (ALT) and direct bilirubin increased in the plasma, while ALT and aspartate aminotransferase (AST) decreased in the liver. Glucose, lactate and pyruvate increased while protein decreased in the plasma; glycogen, pyruvate and lactate decreased in the liver; and glycogen and glucose increased in the muscle. Ammonia increased in the plasma, liver and muscle. The hepatocyte cell shape changed from polyhedral to round after cellular extract injection; there was loss of biliary canaliculus organization, but the biliary duct morphology was conserved in the liver parenchyma. In conclusion, microcystins present in the cellular extract of R. fernandoi strain R28 affect the liver structure of H. malabaricus, but the liver was able to continuously produce energy by adjusting its intermediate metabolism; glycogenolysis and gluconeogenesis maintained glucose homeostasis and energy supply.

Comparison of the effects of difenacoum and brodifacoum on the ultrastructure of rat liver cells

We used transmission electron microscopy to examine the cytotoxic effects of the second-generation anticoagulant rodenticides difenacoum and brodifacoum on rat liver. A single dose of difenacoum or brodifacoum was administered to rats by gastric gavage and liver samples were taken after 24 h, four days or seven days. In the livers of rats treated with difenacoum for 24 h, hepatocytes typically showed increased numbers of lysosomes, as well as enlargement of both the perinuclear space and the cisternae of the rough endoplasmic reticulum (RER), while sinusoids were irregularly shaped and contained Kupffer cells. Similar irregularities occurred in brodifacoum-treated rats at the same time point, but additionally increased numbers of vacuoles, damaged mitochondrial cristae, and clumping of chromatin were observed in hepatocytes, and hemolysed erythrocytes were noted in the sinusoids. Comparable findings were made in each group of rats after four days. After seven days of difenacoum treatment, hepatocytes suffered loss of cytoplasmic material and mitochondrial shrinkage, while RER cisternae became discontinuous. In contrast, exposure to brodifacoum for seven days caused the formation of numerous vacuoles and lipid droplets, disordered mitochondrial morphology, chromatin clumping and invagination of the nuclear envelope in hepatocytes. Sinusoids in the livers of rodenticide-treated rats contained an accumulation of dense material, lipid droplets, cells with pycnotic nuclei and hemolysed erythrocytes. Overall, our results show that brodifacoum causes more severe effects in liver cells than difenacoum. Thus our microscopic data along with additional biochemical assays point to a severe effect of rodenticide on vertebrates.

Hepatocytic parental progenitor cells of rat small hepatocytes maintain self-renewal capability after long-term culture

The liver has a variety of functions for maintaining homeostasis, and hepatocytes play a major role. In contrast with the high regenerative capacity of mature hepatocytes (MHs) in vivo, they have not been successfully expanded ex vivo. Here we demonstrate that CD44-positive cells sorted from small hepatocyte (SH) colonies derived from a healthy adult rat liver can proliferate on a Matrigel-coated dish in serum-free chemically defined medium; in addition, a subpopulation of the cells can divide more than 50 times in a period of 17 weeks every 4-week-passage. The passage cells retained the capability to recover highly differentiated functions, such as glycogen storage, CYP activity and bile secretion. When Matrigel-treated cells from the third passage were transplanted into retrorsine/partial hepatectomy-treated rat livers, the cells engrafted to differentiate into MHs and cholangiocytes. These results suggest that long-term cultured CD44+ SHs retain hepatocytic characteristics in vitro and the capability to differentiate into hepatocytes and cholangiocytes in vivo. Thus, a newly identified subpopulation of MHs possessing the attributes of hepatocytic stem/progenitor cells can be passaged several times without losing hepatocytic characteristics.

Effect of HSP27 and Cofilin in the injury of hypoxia/reoxygenation on hepatocyte membrane F-actin microfilaments

Hypoxia-reoxygenation (H/R) injury hepatocyte models were established to simulate the ischemia/reperfusion injury of transplanted organ. Through the study of the molecular mechanism of H/R on the F-actin damage of the liver cytomembrane, the mechanism of F-actin damage induced by ischemia and reperfusion was studied from the level of cell and molecule.The hypoxic environment of cells in vitro was simulated by chemical hypoxia agent CoCl2. Liver cells were detected by MTT, H/R group was subdivided into 3 subgroups: H/R 2, 4, and 6 h. Changes of cell shape and the growth state, apoptosis, ultrastructural changes, and the changes in F-actin microfilament content were observed. Heat shock protein 27 (HSP27), Cofilin, and F-actin gene and protein levels were determined by real-time polymerase chain reaction and western blot assay, respectively.Cells showed circular adherence growth under normal circumstances, while the spindle cells and shedding cells were significantly increased in H/R groups. Apoptosis cells in H/R group were increased significantly with the extension of hypoxia time. The number of endoplasmic reticulum was decreased significantly in the H/R group, the mitochondrion hydropic was degenerated and the glycogen was disappeared. The F-actin fibers in the H/R group were disordered, the morphology of the fibers was obviously decreased, and the fluorescence staining decreased obviously (P < .05). The transcription and expression levels of HSP27, Cofilin, and F-actin were significantly lower than those in the control group (P < .05).These results demonstrate that H/R can affect the correct assembly of F-actin microfilaments and weakens the normal cycle of F-actin microfilaments through inhibiting the protein expression and gene transcription of HSP27 and Cofilin in hepatocytes, thereby changing the skeleton of F-actin microfilaments.

Functional characterization of lysophosphatidic acid receptor 1 mutants identified in rat cancer tissues

Lysophosphatidic acid (LPA), an extracellular lipid mediator, exerts various cellular effects through activation of LPA receptors, LPA₁-LPA₆, in many types of cells including cancer cells. We recently found several missense mutations of Lpar1 in rat cancer tissues. One of these mutations is located at the extracellular tip of the seventh transmembrane domain of LPA₁, and another three mutations are found within the NPXXY motif in the seventh transmembrane domain. These mutants are designated F295S LPA₁ and P308S, I310T, and Y311H LPA₁, respectively. Here, we examined the functions of these LPA₁ mutants. Compared with wild-type (WT) LPA₁, F295S, P308S, and I310T LPA₁ showed decreased maximal responses in inhibition of cAMP formation, Ca²⁺ mobilization, and cytoskeletal changes. Y311H LPA₁ failed to show LPA-induced cellular responses. However, these LPA₁ mutants were internalized in response to LPA exposure. Finally, while WT and F295S LPA₁ showed a similar, broad distribution throughout the cell, P308S, I310T, and Y311H LPA₁ displayed a restricted cellular distribution and co-localized with the endoplasmic reticulum. These data suggest that the LPA₁ mutants perturb LPA signaling in cancer tissues.

Berberine attenuates oxidative stress and hepatocytes apoptosis via protecting mitochondria in blunt snout bream Megalobrama amblycephala fed high-fat diets

High-fat diets may have favorable effects on growth and cost, but high-fat diets often induce excessive fat deposition, resulting in liver damage. This study aimed to identify the hepatoprotective of a Chinese herb (berberine) for blunt snout bream (Megalobrama amblycephala). Fish were fed with a normal diet (LFD, 5 % fat), high-fat diet (HFD, 15 % fat) or berberine-supplemented diets (BSD, 15 % fat with berberine 50 or 100 mg/kg level) for 8 weeks. After the feeding, histology, oxidative status and mitochondrial function of liver were assessed. The results showed that HFD caused fat accumulation, oxidative stress and apoptosis in hepatocytes of fish. Hepatocytes in HFD group appeared to be hypertrophied, with larger liver cells diameter than these of LFD group. Berberine-supplemented diets could attenuate oxidative stress and hepatocytes apoptosis. HFD induced the decreasing mitochondrial complexes activities and bulk density and surface area density. Berberine improved function of mitochondrial respiratory chain via increasing the complex activities. Moreover, the histological results showed that berberine has the potential to repair mitochondrial ultrastructural damage and elevate the density in cells. In conclusion, our study demonstrated that berberine has attenuated liver damage induced by the high fat mainly via the protection for mitochondria.

Long-Term Selenium-Deficient Diet Induces Liver Damage by Altering Hepatocyte Ultrastructure and MMP1/3 and TIMP1/3 Expression in Growing Rats

The effects of selenium (Se)-deficient diet on the liver were evaluated by using growing rats which were fed with normal and Se-deficient diets, respectively, for 109 days. The results showed that rats fed with Se-deficient diet led to a decrease in Se concentration in the liver, particularly among male rats from the low-Se group. This causes alterations to the ultrastructure of hepatocytes with condensed chromatin and swelling mitochondria observed after low Se intake. Meanwhile, pathological changes and increased fibrosis in hepatic periportal were detected by hematoxylin and eosin and Masson's trichrome staining in low-Se group. Furthermore, through immunohistochemistry (IHC) staining, higher expressions of metalloproteinases (MMP1/3) and their tissue inhibitors of metalloproteinases (TIMP1/3) were observed in the hepatic periportal of rats from the low-Se group. However, higher expressions of MMP1/3 and lower expressions of TIMP1/3 were detected in hepatic central vein and hepatic sinusoid. In addition, upregulated expressions of MMP1/3 and downregulated expressions of TIMP1/3 at the messenger RNA (mRNA) and protein levels also appeared to be relevant to low Se intake. In conclusion, Se-deficient diet could cause low Se concentration in the liver, alterations of hepatocyte ultrastructure, differential expressions of MMP1/3 and TIMP1/3 as well as fibrosis in the liver hepatic periportal.

The Intracellular Cholesterol Transport Inhibitor U18666A Inhibits the Exosome-Dependent Release of Mature Hepatitis C Virus

Hepatitis C virus (HCV) particles are described as lipoviroparticles which are released similarly to very-low-density lipoproteins (VLDLs). However, the release mechanism is still poorly understood; the canonical endoplasmic reticulum-Golgi intermediate compartment (ERGIC) pathway as well as endosome-dependent release has been proposed. Recently, the role of exosomes in the transmission of HCV has been reported. Only a minor fraction of the de novo-synthesized lipoviroparticles is released by the infected cell. To investigate the relevance of multivesicular bodies (MVBs) for viral morphogenesis and release, the MVB inhibitor U18666A was used. Intracellular trafficking was analyzed by confocal microscopy and electron microscopy. Moreover, an mCherry-tagged HCV variant was used. Conditions were established that enable U18666A-dependent inhibition of MVBs without affecting viral replication. Under these conditions, significant inhibition of the HCV release was observed. The assembly of viral particles is not affected. In U18666A-treated cells, intact infectious viral particles accumulate in CD63-positive exosomal structures and large dysfunctional lysosomal structures (multilamellar bodies). These retained particles possess a lower density, reflecting a misloading with lipids. Our data indicate that at least a fraction of HCV particles leaves the cell via the endosomal pathway. Endosomes facilitate the sorting of HCV particles for release or degradation.

IMPORTANCE

There are still a variety of open questions regarding morphogenesis and release of hepatitis C virus. The HCV-infected cell produces significant more viral particles that are released, raising the question about the fate of the nonreleased particles. Moreover, the relevance of the endosomal pathway for the release of HCV is under debate. Use of the MVB (multivesicular body) inhibitor U18666A enabled a detailed analysis of the impact of MVBs for viral morphogenesis and release. It was revealed that infectious, fully assembled HCV particles are either MVB-dependently released or intracellularly degraded by the lysosome. Our data indicate that at least a fraction of HCV particles leaves the cell via the endosomal pathway independent from the constitutive secretory pathway. Our study describes a so-far-unprecedented cross talk between two pathways regulating on the one hand the release of infectious viral particles and on the other hand the intracellular degradation of nonreleased particles.

Effects of a silver nanomaterial on cellular organelles and time course of oxidative stress in a fish cell line (PLHC-1)

Among the nanomaterials currently in commercial products, those based on silver are the most used, and so there is a high probability that silver nanoparticles (AgNPs) will be released into aquatic environments where they could adversely affect aquatic organisms, including fish. Taking this into account, the aim of the present work was to characterize in depth the mechanisms underlying the toxic action of AgNPs using fish cell lines, determining specifically the contribution of alterations in cellular structures and oxidative stress time course to the cytotoxicity of AgNPs. Since liver plays a key role in detoxification, the hepatoma cell line PLHC-1 was used. Exposure to AgNPs (NM-300K, obtained from the Joint Research Centre Repository) caused alterations at the lysosomal and mitochondrial levels at lower concentrations than those that disrupted plasma membrane (evaluated by means of neutral red, alamarBlue, and 5-carboxyfluorescein diacetate, acetoxymethyl ester assays respectively). AgNO₃, used as a control Ag⁺ ion source, produced similar cytotoxic effects but at lower concentrations than AgNPs. Both silver forms caused oxidative disruption but the initial response was delayed in AgNPs until 6h of exposure. Transmission electron microscopy analysis also evidenced the disruption of mitochondrial structures in cells exposed to cytotoxic concentrations of both forms of silver. At non-cytotoxic concentrations, AgNPs were detected inside the nucleoli and mitochondria, thereby pointing to long-term effects. The present work evidences the mutual interaction between the induction of oxidative stress and the alterations of cellular structures, particularly mitochondria, as cytotoxicity mechanisms not exclusively associated to NPs.