Targeting autophagy for the treatment of liver diseases

Autophagy induced by metabolic processes leads to solid tumor cell metastatic dormancy and recurrence

A crucial cellular mechanism that has a complex impact on the biology of cancer, particularly in solid tumors, is autophagy. This review explores how metabolic processes trigger autophagy, which helps metastatic tumor cells go dormant and recur. During metastasis, tumor cells frequently encounter severe stressors, such as low oxygen levels and nutritional deprivation, which causes them to activate autophagy as a survival tactic. This process allows cancer stem cells (CSCs) to withstand severe conditions while also preserving their features. After years of dormancy, dormant disseminated tumor cells (DTCs) may reappear as aggressive metastatic cancers. The capacity of autophagy to promote resistance to treatments and avoid immune detection is intimately related to this phenomenon. According to recent research, autophagy promotes processes, such as the epithelial-to-mesenchymal transition (EMT) and helps build a pre-metastatic niche, which makes treatment strategies more challenging. Autophagy may be a promising therapeutic target because of its dual function as a tumor suppressor in early-stage cancer and a survival promoter in advanced stages. To effectively treat metastatic diseases, it is crucial to comprehend how metabolic processes interact with autophagy and affect tumor behavior. In order to find novel therapeutic approaches that can interfere with these processes and improve patient outcomes, this study highlights the critical need for additional investigation into the mechanisms by which autophagy controls tumor dormancy and recurrence.

Mechanisms and implications of podocyte autophagy in chronic kidney disease

Autophagy is a protective mechanism through which cells degrade and recycle proteins and organelles to maintain cellular homeostasis and integrity. An accumulating body of evidence underscores the significant impact of dysregulated autophagy on podocyte injury in chronic kidney disease (CKD). In this review, we provide a comprehensive overview of the diverse types of autophagy and their regulation in cellular homeostasis, with a specific emphasis on podocytes. Furthermore, we discuss recent findings that focus on the functional role of different types of autophagy during podocyte injury in chronic kidney disease. The intricate interplay between different types of autophagy and podocyte health requires further research, which is critical for understanding the pathogenesis of CKD and developing targeted therapeutic interventions.

Subversion strategies of lysosomal killing by intracellular pathogens

Many pathogenic organisms need to reach either an intracellular compartment or the cytoplasm of a target cell for their survival, replication or immune system evasion. Intracellular pathogens frequently penetrate into the cell through the endocytic and phagocytic pathways (clathrin-mediated endocytosis, phagocytosis and macropinocytosis) that culminates in fusion with lysosomes. However, several mechanisms are triggered by pathogenic microorganisms - protozoan, bacteria, virus and fungus - to avoid destruction by lysosome fusion, such as rupture of the phagosome and thereby release into the cytoplasm, avoidance of autophagy, delaying in both phagolysosome biogenesis and phagosomal maturation and survival/replication inside the phagolysosome. Here we reviewed the main data dealing with phagosome maturation and evasion from lysosomal killing by different bacteria, protozoa, fungi and virus.

Interleukin-1 family cytokines in liver cell death: a new therapeutic target for liver diseases

INTRODUCTION

Liver cell death represents a basic biological process regulating the progression of liver diseases via distinct mechanisms. Accumulating evidence has uncovered participation of interleukin (IL)-1 family cytokines in liver cell death. Upon activation of cell death induced by hepatotoxic stimuli, IL1 family cytokines released by hepatic dead cells stimulate recruitment of immune cells, which in turn influence inflammation and subsequent liver injury, thus highlighting their potential as therapeutic targets in liver diseases. Enhancing our comprehension of mechanisms underlying IL1 family cytokine signaling in cell death responses could pave the way for novel therapeutic interventions aimed at addressing liver cell death-related liver pathologies.

AREAS COVERED

This review summarizes the recent findings reported in preclinical and clinical studies on mechanisms of liver cell death, alongside participation of IL1 family members consisting of IL1α, ILβ, IL18, and IL33 in liver cell death and their significant implications in liver diseases.

EXPERT OPINION

Discovery of new and innovative therapeutic approaches for liver diseases will need close cooperation between fundamental and clinical scientists to better understand the multi-step processes behind IL1 family cytokines' contributions to liver cell death.

Isoginkgetin synergizes with doxorubicin for robust co-delivery to induce autophagic cell death in hepatocellular carcinoma

Doxorubicin (DOX) widely used in hepatocellular carcinoma (HCC) can induce serious side effects and drug resistance. Herein, we aimed to seek a strategy to improve the efficacy and reduce the side effects of DOX in HCC based on an autophagy inducer drug called isoginkgetin (ISO). The design of multifunctional nanocarriers based on hyaluronic acid-conjugated and manganese-doped mesoporous silica nanoparticles (HM) for the co-delivery of antitumor drugs against HCC provided an effective and promising antitumor strategy. Our results showed that HM@ISO@DOX could efficiently inhibit HCC cell proliferation through activating autophagy through AMPKa-ULK1 pathway. Moreover, intravenous injection of HM@ISO@DOX significantly suppressed HCC tumor progression in nude mouse HCC model. Collectively, our findings revealed an anti-HCC mechanism of HM@ISO@DOX through autophagy and provide an effective therapeutic strategy for HCC. STATEMENT OF SIGNIFICANCE: In our study, we constructed a co-delivery system by loading ISO and DOX in the mesoporous channels of manganese-doped mesoporous silica nanoparticles, which could be further conjugated with hyaluronic acid to obtain HM@ISO@DOX. The nanocarriers had been demonstrated to be biodegradable under the acidic and reducing tumor microenvironment, as well as to possess the tumor targeting capability via the conjugated hyaluronic acid. In addition, HM@ISO@DOX enhanced the therapeutic efficacy against human HCC tumor through the combinatorial therapies of chemotherapeutics, Mn2+-mediated chemodynamic therapeutics and autophagic cell death, which might be achieved through AMPK-ULK1 signaling. This work revealed that such a nanomedicine exhibited superior tumor accumulation and antitumor efficiency against HCC with extremely low systemic toxicity in an autophagy-boosted manner.

Possible Cytoprotection of Low Dose Lipopolysaccharide in Rat Thioacetamide-Induced Liver Lesions, Focusing on the Analyses of Hepatic Macrophages and Autophagy

Lipopolysaccharide (LPS) may influence hepatic macrophages and autophagy. We evaluated the potential participation of macrophages and autophagosomes in thioacetamide (TAA)-induced rat liver injury under pretreatment of a low dose LPS (0.1 mg/kg BW, intraperitoneally; nonhepatotoxic dose). F344 rats were pretreated with LPS (LPS + TAA) or saline (TAA alone) at 24 hours before TAA injection (100 mg/kg BW, intraperitoneally); rats were examined on Days 0 (controls), 1, 2, and 3 after TAA injection. Data were compared between TAA alone and LPS + TAA rats. LPS pretreatment significantly reduced TAA-induced hepatic lesion (centrilobular necrosis with inflammation) on Days 1 and 2, being reflected by declined hepatic enzyme values and decreased number of apoptotic cells. LC3B-immunoreacting autophagosomes (as cytoplasmic fine granules) were significantly increased on Days 1 and 2 in hepatocytes of LPS + TAA rats. In LPS + TAA rats, hepatic macrophages reacting to CD68, CD163, and MHC class II mainly on Day 2 and mRNA levels of macrophage-related factors (MCP-1, IL-1β, and IL-4) on Day 1 were significantly decreased. Collectively, the low-dose LPS pretreatment might act as cytoprotection against TAA-induced hepatotoxicity through increased autophagosomes and decreased hepatic macrophages, although the dose/time-dependent cytoprotection of LPS should be further investigated at molecular levels.

The regulation, function, and role of lipophagy, a form of selective autophagy, in metabolic disorders

Autophagy is a conserved method of quality control in which cytoplasmic contents are degraded via lysosomes. Lipophagy, a form of selective autophagy and a novel type of lipid metabolism, has recently received much attention. Lipophagy is defined as the autophagic degradation of intracellular lipid droplets (LDs). Although much remains unknown, lipophagy appears to play a significant role in many organisms, cell types, metabolic states, and diseases. It participates in the regulation of intracellular lipid storage, intracellular free lipid levels (e.g., fatty acids), and energy balance. However, it remains unclear how intracellular lipids regulate autophagy. Impaired lipophagy can cause cells to become sensitive to death stimuli and may be responsible for the onset of a variety of diseases, including nonalcoholic fatty liver disease and metabolic syndrome. Like autophagy, the role of lipophagy in cancer is poorly understood, although analysis of specific autophagy receptors has helped to expand the diversity of chemotherapeutic targets. These studies have stimulated increasing interest in the role of lipophagy in the pathogenesis and treatment of cancer and other human diseases.

Deficiency of SREBP1c modulates autophagy mediated lipid droplet catabolism during oleic acid induced steatosis

Objective

Increased fatty acid and triglyceride synthesis in liver, majorly modulated by Sterol Regulator Elementing Binding Protein 1c (SREBP1c), is one of the main features of non-alcoholic fatty liver disease (NAFLD). In the present study, we aimed to identify the relation between SREBP1c and autophagy mediated lipid droplet (LD) catabolism in oleic acid (OA) induced lipid accumulation.

Methods

Increased LD formation and SREBP1c induction were identified in hepatocytes (AML12 cells) following the OA administration. SREBP1c level was reduced through siRNA against SREBP1c. The amount and the size of LDs were determined by BODIPY, while protein and mRNA expressions were identified by immunoblotting and qRT-PCR, respectively. LD-lysosome colocalization was determined with immunofluorescence.

Results

Increased LD formation and SREBP1c levels were determined at 0.06 mM OA concentration. SREBP1c silencing reduced the number of LDs, while increasing mRNA levels of PPARα. On the other hand, SREBP1c silencing in non-OA and OA treated cells enhanced autophagy mediated LD catabolism.

Conclusion

Our results implicate the effect of SREBP1c deficiency in modulating PPARα signaling and autophagy mediated LD catabolism against OA induced lipid accumulation.

Understanding the implication of autophagy in the activation of hepatic stellate cells in liver fibrosis: are we there yet?

Liver fibrosis (LF) occurs as a result of persistent liver injury and can be defined as a pathologic, chronic, wound-healing process in which functional parenchyma is progressively replaced by fibrotic tissue. As a phenomenon involved in the majority of chronic liver diseases, and therefore prevalent, it exerts a significant impact on public health. This impact becomes even more patent given the lack of a specific pharmacological therapy, with LF only being ameliorated or prevented through the use of agents that alleviate the underlying causes. Hepatic stellate cells (HSCs) are fundamental mediators of LF, which, activated in response to pro-fibrotic stimuli, transdifferentiate from a quiescent phenotype into myofibroblasts that deposit large amounts of fibrotic tissue and mediate pro-inflammatory effects. In recent years, much effort has been devoted to understanding the mechanisms through which HSCs are activated or inactivated. Using cell culture and/or different animal models, numerous studies have shown that autophagy is enhanced during the fibrogenic process and have provided specific evidence to pinpoint the fundamental role of autophagy in HSC activation. This effect involves - though may not be limited to - the autophagic degradation of lipid droplets. Several hepatoprotective agents have been shown to reverse the autophagic alteration present in LF, but clinical confirmation of these effects is pending. On the other hand, there is evidence that implicates autophagy in several anti-fibrotic mechanisms in HSCs that stimulate HSC cell cycle arrest and cell death or prevent the generation of pro-fibrotic mediators, including excess collagen accumulation. The objective of this review is to offer a comprehensive analysis of published evidence of the role of autophagy in HSC activation and to provide hints for possible therapeutic targets for the treatment and/or prevention of LF related to autophagy. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Sodium orthovanadate inhibits growth of acute leukemia HL60 cells and HL60/A cells in vitro

Vanadium is an ultratrace element. The transition metal vanadium, widely exists in the environment and exhibits various biological and physiological effects in the human body, yet with no presently known specific physiological function in mammals. Sodium orthovanadate (SOV) is a kind of vanadium compound. SOV has shown promising antineoplastic activity in several human cancers. But the effects of SOV on acute promyelocytic leukemia (APL) are still unknown. In the present study, for the first time, we found that SOV could inhibit proliferation, induce G2/M cell cycle arrest and apoptosis, and could inhibit autophagy of acute leukemia cell lines in vitro. Thus, our findings suggest that SOV could effectively suppress the growth of acute leukemia HL60 cells and HL60/A cells through the regulations of proliferation, cell cycle, apoptosis and autophagy, and thus may act as a potential therapeutic agent in APL treatment.

The Role of Autophagy in Liver Cancer: Crosstalk in Signaling Pathways and Potential Therapeutic Targets

Autophagy is an evolutionarily conserved lysosomal-dependent pathway for degrading cytoplasmic proteins, macromolecules, and organelles. Autophagy-related genes (Atgs) are the core molecular machinery in the control of autophagy, and several major functional groups of Atgs coordinate the entire autophagic process. Autophagy plays a dual role in liver cancer development via several critical signaling pathways, including the PI3K-AKT-mTOR, AMPK-mTOR, EGF, MAPK, Wnt/β-catenin, p53, and NF-κB pathways. Here, we review the signaling pathways involved in the cross-talk between autophagy and hepatocellular carcinoma (HCC) and analyze the status of the development of novel HCC therapy by targeting the core molecular machinery of autophagy as well as the key signaling pathways. The induction or the inhibition of autophagy by the modulation of signaling pathways can confer therapeutic benefits to patients. Understanding the molecular mechanisms underlying the cross-link of autophagy and HCC may extend to translational studies that may ultimately lead to novel therapy and regimen formation in HCC treatment.

Osteocalcin prevents insulin resistance, hepatic inflammation, and activates autophagy associated with high-fat diet-induced fatty liver hemorrhagic syndrome in aged laying hens

The aim of this study was to investigate the effects of osteocalcin (OCN) on fatty liver hemorrhagic syndrome (FLHS) in aged laying hens. Thirty 68-week-old White Plymouth laying hens were randomly assigned into conventional single-bird cages, and the cages were randomly allocated into one of 3 treatments (n = 10): normal diet (ND + vehicle, ND + V), high-fat diet (HFD + vehicle, HFD + V), and HFD + OCN (3 μg/bird, 1 time/2 d, i.m.) for 40 d. At day 30, oral glucose tolerance tests (OGTT) and insulin tolerance tests (ITT) were performed. At the end of experiment, the hens were euthanized followed by blood collection. The plasma aspartate transaminase (AST), alkaline phosphatase (ALP), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were measured using an automatic biochemistry analyzer. Pathological changes in the liver were examined under both light and transmission electron microscopes. The plasma inflammatory factors including interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha (TNF-α) were analyzed by ELISA, and the gene expressions of these inflammatory factors in the liver were analyzed by real-time PCR. The level of oxidative stress was evaluated using malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) assay kits, respectively. The results showed that HFD + V hens had more severe liver hemorrhage and fibrosis than ND + V hens (P < 0.05). The ultramicrostructural examination showed that hepatocytes of HFD + V hens exhibited necrotic pyknosis showing great intracellular electron, mitochondrial swelling, shrunk nucleus, and absence of autolysosomes. Osteocalcin mitigated HFD + V-induced pathological changes in aged laying hens. High-fat diet + OCN hens had higher insulin sensitivity; lower liver concentrations of MDA (P = 0.12) but higher GSH-Px (P < 0.05); and lower blood TNF-α concentrations (P < 0.05) and mRNA expressions (P < 0.05) than HFD + V hens. These results suggest OCN functions in preventing the FLHS process in old laying hens through inhibiting excessive energy diet-induced metabolic disorder, oxidative stress, and related pathological damage.

Lipophagy: Molecular Mechanisms and Implications in Metabolic Disorders

Autophagy is an intracellular degradation system that breaks down damaged organelles or damaged proteins using intracellular lysosomes. Recent studies have also revealed that various forms of selective autophagy play specific physiological roles under different cellular conditions. Lipid droplets, which are mainly found in adipocytes and hepatocytes, are dynamic organelles that store triglycerides and are critical to health. Lipophagy is a type of selective autophagy that targets lipid droplets and is an essential mechanism for maintaining homeostasis of lipid droplets. However, while processes that regulate lipid droplets such as lipolysis and lipogenesis are relatively well known, the major factors that control lipophagy remain largely unknown. This review introduces the underlying mechanism by which lipophagy is induced and regulated, and the current findings on the major roles of lipophagy in physiological and pathological status. These studies will provide basic insights into the function of lipophagy and may be useful for the development of new therapies for lipophagy dysfunction-related diseases.

The Upstream Pathway of mTOR-Mediated Autophagy in Liver Diseases

Autophagy, originally found in liver experiments, is a cellular process that degrades damaged organelle or protein aggregation. This process frees cells from various stress states is a cell survival mechanism under stress stimulation. It is now known that dysregulation of autophagy can cause many liver diseases. Therefore, how to properly regulate autophagy is the key to the treatment of liver injury. mechanistic target of rapamycin (mTOR)is the core hub regulating autophagy, which is subject to different upstream signaling pathways to regulate autophagy. This review summarizes three upstream pathways of mTOR: the phosphoinositide 3-kinase (PI3K)/protein kinase (AKT) signaling pathway, the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, and the rat sarcoma (Ras)/rapidly accelerated fibrosarcoma (Raf)/mitogen-extracellular activated protein kinase kinase (MEK)/ extracellular-signal-regulated kinase (ERK) signaling pathway, specifically explored their role in liver fibrosis, hepatitis B, non-alcoholic fatty liver, liver cancer, hepatic ischemia reperfusion and other liver diseases through the regulation of mTOR-mediated autophagy. Moreover, we also analyzed the crosstalk between these three pathways, aiming to find new targets for the treatment of human liver disease based on autophagy.

Inactivation of Sirtuin2 protects mice from acetaminophen-induced liver injury: possible involvement of ER stress and S6K1 activation

Acetaminophen (APAP) overdose can cause hepatotoxicity by inducing mitochondrial damage and subsequent necrosis in hepatocytes. Sirtuin2 (Sirt2) is an NAD⁺-dependent deacetylase that regulates several biological processes, including hepatic gluconeogenesis, as well as inflammatory pathways. We show that APAP decreases the expression of Sirt2. Moreover, the ablation of Sirt2 attenuates APAP-induced liver injuries, such as oxidative stress and mitochondrial damage in hepatocytes. We found that Sirt2 deficiency alleviates the APAP-mediated endoplasmic reticulum (ER) stress and phosphorylation of the p70 ribosomal S6 kinase 1 (S6K1). Moreover, Sirt2 interacts with and deacetylates S6K1, followed by S6K1 phosphorylation induction. This study elucidates the molecular mechanisms underlying the protective role of Sirt2 inactivation in APAP-induced liver injuries.

Lipid Droplet Formation and Lipophagy in Fatty Liver Disease

Lipid droplets (LDs) are key sites of neutral lipid storage that can be found in all cells. Metabolic imbalances between the synthesis and degradation of LDs can result in the accumulation of significant amounts of lipid deposition, a characteristic feature of hepatocytes in patients with fatty liver disease, a leading indication for liver transplant in the United States. In this review, the authors highlight new literature related to the synthesis and autophagic catabolism of LDs, discussing key proteins and machinery involved in these processes. They also discuss recent findings that have revealed novel genetic risk factors associated with LD biology that contribute to lipid retention in the diseased liver.

Inhibition of ghrelin o-acyltransferase attenuated lipotoxicity by inducing autophagy via AMPK-mTOR pathway

Background

Nonalcoholic fatty liver disease (NAFLD) has been considered the most commonly occurring chronic hepatopathy in the world. Ghrelin o-acyltransferase (GOAT) is an acylation enzyme which has an acylated position 3 serine on ghrelin. Recent investigation revealed that activated autophagy could attenuate liver steatosis. The aim of this study was to explore therapeutic roles that inhibit GOAT exerted in NAFLD, and its potential association with autophagy.

Materials and methods

Human LO2 cells were pretreated with siRNA-GOAT to induce liver steatosis using free fatty acids (FFAs). A chronic NAFLD model was established by feeding male mice C57bl/6 with high-fat diet (HFD) for 56 days with GO-CoA-Tat administrated subcutaneously. Lipid droplets were identified by Oil Red O stains. Body weight (BW) of mice was measured every week. Autophagy, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), serum biochemical indicators (glucose [Glu], total cholesterol [TC], triglyceride [TG], aspartate aminotransferase [AST], alanine aminotransferase [ALT]) and signaling pathway proteins of phosphorylated AMPK–mTOR were measured.

Results

The TG contents of the FFA and HFD groups were decreased by the inhibition of GOAT. Among mice treated with GO-CoA-Tat and siRNA-GOAT, IL-6 and TNF-α concentrations were remarkably decreased. Indicators of liver injury such as ALT and AST were also remarkably decreased among mice treated with GO-CoA-Tat. Likewise, GO-CoA-Tat significantly reduced the BW of mice and serum TG, TC and Glu. Autophagy was induced along with reduced lipids in the cells of the FFA and HFD groups. The inhibition of GOAT upregulated autophagy via AMPK–mTOR restoration.

Conclusion

These results indicate that the inhibition of GOAT attenuates lipotoxicity by autophagy stimulation via AMPK–mTOR restoration and offers innovative evidence for using GO-CoA-Tat or siRNA-GOAT in NAFLD clinically.

New insights into Nod-like receptors (NLRs) in liver diseases

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Nod-like receptors (NLRs) are intracellular innate immune sensors of microbes and danger signals that control multiple aspects of inflammatory responses. Recent studies demonstrated that NLRs are expressed and activated in innate immune cells as well as in parenchymal cells in the liver. For example, NLRP3 signaling is involved in liver ischemia-reperfusion (I/R) injury and silencing of NLRP3 can protect the liver from I/R injury. In this article, we review the evidence that highlights the critical importance of NLRs in the prevalent liver diseases. The significance of NLR-induced intracellular signaling pathways and cytokine production is also evaluated.

Green tea activity and iron overload induced molecular fibrogenesis of rat liver

Iron overload toxicity was shown to associate with chronic liver diseases which lead to hepatic fibrosis and subsequently the progression to cancer through oxidative stress and apoptotic pathways. Green tea potential activity as chelating, anti-oxidative, or anti-apoptotic mechanisms against metal toxicity was poorly clarified. Here, we are trying to evaluate the anti-oxidant and anti-apoptotic properties of green tea in the regulation of serum hepcidin levels, reduction in iron overloads, and improve of liver fibrosis in iron overloaded experimental rats. Three groups of male adult rats were randomly classified into three groups and treated as follows: control rats, iron treated rats for two months in drinking water followed by either vehicle or green tea extract (AGTE; 100 mg/kg) treatment for 2 more months. Thereafter, we studied the effects of AGTE on iron overload-induced lipid peroxidation, anti-oxidant depletion, liver cell injury and apoptosis. Treatment of iron-overloaded rats with AGTE resulted in marked decreases in iron accumulation within liver, depletion in serum ferritin, and hepcidin levels. Iron-overloaded rats had significant increase in malonyldialdehyde (MDA), a marker of lipid peroxidation and nitric oxide (NO) in liver when compared to control group. Also, significant change in cytochrome c and DNA content as apoptotic markers were reported in iron treated rats. The effects of iron overload on lipid peroxidation, NO levels, cytochrome c and DNA content were significantly reduced by the intervention treatment with AGTE (P < 0.001). Furthermore, the endogenous anti-oxidant capacities/levels (TAC) in liver were also significantly decreased in chronic iron overload and administration of AGTE restored the decrease in the hepatic antioxidant activities/levels. Also, hepatic hepcidin was shown to be significantly correlated with oxidative and apoptotic relating biomarkers as well as an improvement in liver fibrosis of iron treated rats following AGTE treatment. In-vitro analysis showed that, the improvement in iron toxicity of the liver depend mainly on antioxidant and protective ability of green tea polyphenolic compounds especiallyepigallocatechin-3-gallate (EGCG). Our study showed that green tea extract (GTE) ameliorates iron overload induced hepatotoxicity, apoptosis and oxidative stress in rat liver via inhibition of hepatic iron accumulation; improve of liver antioxidant capacity, and down regulation of serum hepcidin as well as reduction in the release of apoptotic relating proteins.

Serum Golgi protein 73 is a prognostic biomarker of liver transplantation patients

BACKGROUND

The death after liver transplantation (LT) was most commonly caused by HCC recurrence. Golgi protein 73 (GP73), a type II Golgi membrane protein, has been proved to be a better serum marker for HCC.

OBJECTIVE

This study aims to clarify the relationship between serum GP73 levels and tumor recurrence as well as survival of HCC patients after LT.

METHODS

Between November 2003 and July 2008, serum samples from 60 liver transplantation patients and 72 healthy individuals were collected. ELISA and microparticle enzyme immunoassay were used to measure serum GP73 and AFP levels. Patient survival was analyzed using log-rank test along with Kaplan-Meier method. Receiver operating characteristic (ROC) curve was utilized to analyze the diagnostic value of serum GP73 levels. Cox regression was utilized to analyze prognostic factors with multiple variables.

RESULTS

Serum GP73 concentrations in HCC patients were much higher than that in healthy controls (P<0.001). Patients with lower serum GP73 levels at LT-6Month had better overall survival and recurrence-free survival than those with higher serum GP73 levels. ROC analyzing results showed that higher serum GP73 levels at 6 month post-LT could significantly predict mortality (P=0.020) as well as HCC recurrence (P=0.001) after liver transplantation. Multivariate analysis revealed that serum GP73 levels at LT-6Month was an independent predictor of good prognosis (P=0.002).

CONCLUSION

Serum GP73 levels could be used to predict tumor recurrence and survival in HCC sufferers after LT.

Inhibition of PI3K/AKt/mTOR signaling pathway protects against d-galactosamine/lipopolysaccharide-induced acute liver failure by chaperone-mediated autophagy in rats

OBJECTIVE

This study aims to investigate the effects of PI3K/AKt/mTOR signaling pathway on the proliferation and apoptosis in acute liver failure (ALF) by chaperone mediated autophagy (CMA).

METHODS

The hepatocytes extracted from both normal rats and rats with ALF were assigned to control, acute injury, P13K agonist, and P13K inhibitor groups. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used as part of this investigation to detect the expression of PI3K/AKt/mTOR signaling pathway related-proteins (PI3K, AKt, mTOR), apoptosis related-proteins (Fas, Bax, Bcl-2), chaperone-mediated autophagy (CMA) marker proteins (LAMP-2A, HSC 70), p-PI3K, p-AKt, p-4E-BPI, and p-S6K. An MTT assay was used for analysis of cell proliferation after transfection. Flow cytometry is performed to detect the cell apoptosis.

RESULTS

In comparison to the normal group, the model group showed enhanced positive rate of PI3K, AKt, mTOR, increased expression levels of PI3K, AKt, mTOR, Fas, Bax, p-PI3K, p-AKt, p-4E-BPI and p-S6K, reduced expression levels of Bcl-2, LAMP-2A and HSC 70. The results in vitro experiment: compared with the acute injury group, the PI3K agonist group showed elevated expression levels of PI3K, AKt, mTOR, Fas, Bax, p-PI3K, p-AKt, p-4E-BPI and p-S6K, decreased expression levels of Bcl-2, LAMP-2A and HSC 70, inhibited cell proliferation, more arrested cells in G1 stage, and promoted cell apoptosis. Opposing this, the P13K inhibitor group exhibited an opposite trend.

CONCLUSION

In conclusion, inhibition of the PI3K/AKt/mTOR signaling pathway plays a protective role in ALF by promoting CMA expression, which could arrest cell proliferation and promote cell apoptosis.

Breaking fat: The regulation and mechanisms of lipophagy

Lipophagy is defined as the autophagic degradation of intracellular lipid droplets (LDs). While the field of lipophagy research is relatively young, an expansion of research in this area over the past several years has greatly advanced our understanding of lipophagy. Since its original characterization in fasted liver, the contribution of lipophagy is now recognized in various organisms, cell types, metabolic states and disease models. Moreover, recent studies provide exciting new insights into the underlying mechanisms of lipophagy induction as well as the consequences of lipophagy on cell metabolism and signaling. This review summarizes recent work focusing on LDs and lipophagy as well as highlighting challenges and future directions of research as our understanding of lipophagy continues to grow and evolve. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.

Association between MFN2 gene polymorphisms and the risk and prognosis of acute liver failure: a case-control study in a Chinese population

This study aimed to determine the role of mitofusin 2 (MFN2) gene polymorphisms in the risk and prognosis of acute liver failure (ALF). A total of 298 blood samples were collected from 138 ALF patients (case group) and 160 healthy participants (control group). Coagulation function, glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), total bilirubin (TB), blood ammonia and lactic acid (LA) were measured. The predictive evaluation of MFN2 gene polymorphisms in the risk and prognosis of ALF patients was estimated using Kaplan-Meier survival analysis, haplotype analysis, binary logistic regression analysis and Cox regression analysis. Higher levels of GPT, GOT, TB, blood ammonia and LA were observed in ALF patients with the GG genotype of rs873457 or the TT genotype of rs4846085 than in those with the CC genotype of these two SNPs. The GTACAGC and GTGTGGC haplotypes were a protective factor and a risk factor for ALF, respectively. Blood ammonia and LA levels were independent risk factors and the CC genotype of rs873457 and the CC genotype of rs4846085 were protective factors for ALF. ALF patients with the GG genotype of rs873457 or the TT genotype of rs4846085 had a lower survival rate than those with other genotypes of these two SNPs. The rs4846085 and rs873457 polymorphisms were both independent factors affecting the prognosis of ALF patients. MFN2 gene polymorphisms (rs873457, rs2336384, rs1474868, rs4846085 and rs2236055) may be associated with ALF and the rs873457 and rs4846085 polymorphisms are correlated with the risk and prognosis of ALF.

Inhibition of Kupffer Cell Autophagy Abrogates Nanoparticle-Induced Liver Injury

The possible adverse effects of engineered nanomaterials on human health raise increasing concern as our research on nanosafety intensifies. Upon entry into a human body, whether intended for a theranostic purpose or through unintended exposure, nanomaterials tend to accumulate in the liver, leading to hepatic damage. A variety of nanoparticles, including rare earth upconversion nanoparticles (UCNs), have been reported to elicit hepatotoxicity, in most cases through inducing immune response or activating reactive oxygen species. Many of these nanoparticles also induce autophagy, and autophagy inhibition has been shown to decrease UCN-induced liver damage. Herein, using UCNs as a model engineered nanomaterial, this study uncovers a critical role for Kupffer cells in nanomaterial-induced liver toxicity, as depletion of Kupffer cells significantly exacerbates UCN-induced liver injury. Furthermore, UCN-induced prodeath autophagy in Kupffer cells, and inhibition of autophagy with 3-MA, a well-established chemical inhibitor of autophagy, enhances Kupffer cell survival and further abrogates UCN-induced liver toxicity. The results reveal the critical importance of Kupffer cell autophagy for nanoparticle-induced liver damage, and inhibition of autophagy may constitute a novel strategy for abrogating nanomaterial-elicited liver toxicity.

The hypertension drug, verapamil, activates Nrf2 by promoting p62-dependent autophagic Keap1 degradation and prevents acetaminophen-induced cytotoxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) provides a cellular defense against oxidative stress by inducing the expression of antioxidant and detoxification enzymes. The calcium antagonist, verapamil, is an FDA-approved drug prescribed for the treatment of hypertension. Here, we show that verapamil acts as a potent Nrf2 activator without causing cytotoxicity, through degradation of Kelch-like ECH-associated protein 1 (Keap1), a Nrf2 repressor. Furthermore, verapamil-induced Keap1 degradation is prominently mediated by a p62-dependent autophagic pathway. Correspondingly, verapamil protects cells from acetaminophen-induced oxidative damage through Nrf2 activation. These results demonstrated the underlying mechanisms for the protective role of verapamil against acetaminophen-induced cytotoxicity.

Astragaloside II sensitizes human hepatocellular carcinoma cells to 5-fluorouracil via suppression of autophagy

OBJECTIVES

Inhibition of autophagy has been increasingly recognized as a potential therapeutic approach against cancer. Our previous reports showed that Astragaloside II improves hepatic cancer cells resistance by downregulating MDR1 and P-gp .The purpose of this study was to further investigated the effect of autophagy on AS-II reversing multidrug resistance and its molecular mechanism in hepatocellular carcinoma cells in vitro.

METHODS

Bel-7402 and Bel-7402/FU cell lines were used in this study. Western blot was used to detect the expression of autophagy-related protein, p-mTOR and p-p79s6k, MTT was used to analyse cell viability, GFP-LC3 punctate dots distribution was observed by GFP-LC3 transient transfection under fluorescence microscopy and silencing of autophagy-related genes was detected by small interfering RNA transfection.

KEY FINDINGS

Astragaloside II was able to significantly decrease the expression of LC3-II and Beclin-1 in a dose-dependent manner, Astragaloside II (80 μm) further decreased LC3-II formation, Beclin-1 and GFP-LC3 puncta dots stimulated with 5-fluorouracil (0.2 mm) in Bel-7402/FU cells (P < 0.05). In addition, Astragaloside II is capable of sensitizing cells to 5-fluorouracil-induced cell death via inhibition of pro-survival autophagy involvement of MAPK-mTOR pathway.

CONCLUSIONS

These findings suggested that Astragaloside II could suppress autophagy by interfering with Beclin-1 and LC3 via MAPK-mTOR pathway, through which sensitized human cancer resistant cells to 5-FU-induced cell death.

Persistency of Enlarged Autolysosomes Underscores Nanoparticle-Induced Autophagy in Hepatocytes

The diverse biological effects of nanomaterials form the basis for their applications in biomedicine but also cause safety issues. Induction of autophagy is a cellular response after nanoparticles exposure. It may be beneficial in some circumstances, yet autophagy-mediated toxicity raises an alarming concern. Previously, it has been reported that upconversion nanoparticles (UCNs) elicit liver damage, with autophagy contributing most of this toxicity. However, the detailed mechanism is unclear. This study reveals persistent presence of enlarged autolysosomes in hepatocytes after exposure to UCNs and SiO₂ nanoparticles both in vitro and in vivo. This phenomenon is due to anomaly in the autophagy termination process named autophagic lysosome reformation (ALR). Phosphatidylinositol 4-phosphate (PI(4)P) relocates onto autolysosome membrane, which is a key event of ALR. PI(4)P is then converted into phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂ ) by phosphatidylinositol-4-phosphate 5-kinase. Clathrin is subsequently recruited by PI(4,5)P₂ and leads to tubule budding of ALR. Yet it is observed that PI(4)P cannot be converted in nanoparticle-treated hepatocytes cells. Exogenous supplement of PI(4,5)P₂ suppresses the enlarged autolysosomes in vitro. Abolishment of these enlarged autolysosomes by autophagy inhibitor relieves the hepatotoxicity of UCNs in vivo. The results provide evidence for disrupted ALR in nanoparticle-treated hepatocytes, suggesting that the termination of nanoparticle-induced autophagy is of equal importance as the initiation.

Autophagy induced by purple pitanga (Eugenia uniflora L.) extract triggered a cooperative effect on inducing the hepatic stellate cell death

Activated hepatic stellate cells (HSC) are the major source of collagen I in liver fibrosis. Eugenia uniflora L. is a tree species that is widely distributed in South America. E. uniflora L. fruit-popularly known as pitanga-has been shown to exert beneficial properties. Autophagy contributes to the maintenance of cellular homeostasis and survival under stress situation, but it has also been suggested to be an alternative cell death pathway. Mitochondria play a pivotal role on signaling cell death. Mitophagy of damaged mitochondria is an important cell defense mechanism against organelle-mediated cell death signaling. We previously found that purple pitanga extract induced mitochondrial dysfunction, cell cycle arrest, and death by apoptosis and necrosis in GRX cells, a well-established activated HSC line. We evaluated the effects of 72-h treatment with crescent concentrations of purple pitanga extract (5 to 100 μg/mL) on triggering autophagy in GRX cells, as this is an important mechanism to cells under cytotoxic conditions. We found that all treated cells presented an increase in the mRNA expression of autophagy-related protein 7 (ATG7). Concomitantly, flow cytometry and ultrastructural analysis of treated cells revealed an increase of autophagosomes/autolysosomes that consequentially led to an increased mitophagy. As purple pitanga extract was previously found to be broadly cytotoxic to GRX cells, we postulated that autophagy contributes to this scenario, where cell death seems to be an inevitable fate. Altogether, the effectiveness on inducing activated HSC death can make purple pitanga extract a good candidate on treating liver fibrosis.

Identifying Novel Targets for Treatment of Liver Fibrosis: What Can We Learn from Injured Tissues which Heal Without a Scar?

The liver is unique in that it is able to regenerate. This regeneration occurs without formation of a scar in the case of non-iterative hepatic injury. However, when the liver is exposed to chronic liver injury, the purely regenerative process fails and excessive extracellular matrix proteins are deposited in place of normal liver parenchyma. While much has been discovered in the past three decades, insights into fibrotic mechanisms have not yet lead to effective therapies; liver transplant remains the only cure for advanced liver disease. In an effort to broaden the collection of possible therapeutic targets, this review will compare and contrast the liver wound healing response to that found in two types of wound healing: scarless wound healing of fetal skin and oral mucosa and scar-forming wound healing found in adult skin. This review will examine wound healing in the liver and the skin in relation to the role of humoral and cellular factors, as well as the extracellular matrix, in this process. While several therapeutic targets are similar between fibrotic liver and adult skin wound healing, others are unique and represent novel areas for hepatic anti-fibrotic research. In particular, investigations into the role of hyaluronan in liver fibrosis and fibrosis resolution are warranted.

NLRC5 regulates TGF-β1-induced proliferation and activation of hepatic stellate cells during hepatic fibrosis

Therapeutic management of liver fibrosis remains an unsolved clinical problem. Hepatic accumulation of extracellular matrix, mainly collagen, is mediated by the production of transforming growth factor-β1 (TGF-β1) in hepatic stellate cells (HSCs). NLRC5, the largest member of the NLR protein family, has recently been identified as a critical regulator of immune responses. Novel evidence shows that NLRC5 is an important negative modulator of inflammatory pathways. Herein, we determined the regulation of NLRC5 in liver fibrogenesis and its underlying mechanisms. We have shown that NLRC5 was upregulated in human liver fibrotic tissues. Overexpression of NLRC5 resulted in an upregulation of collagen 1 and α-smooth muscle actin expression in HSC LX-2 cells, which was inhibited by NLRC5 knockdown with its siRNA. Furthermore, NLRC5 deficiency significantly suppressed TGF-β1-induced proliferation but increased apoptosis (i.e., increased caspases-3, DR4 and DR5) in LX-2 cells. In addition, knockdown of NLRC5 promoted the activation of NF-κB signaling pathways but abrogated phosphorylation of Smad2 and Smad3 proteins in response to TGF-β1. These results indicate that NLRC5 is a potent pro-fibrogenic molecule for HSC activation through TGF-β1/Smad and NF-κB signaling pathways. NLRC5 inhibition would be a promising therapeutic avenue for treating hepatic fibrosis.

The Role of Autophagy in Hepatocellular Carcinoma

Autophagy is a catabolic process involved in cellular homeostasis under basal and stressed conditions. Autophagy is crucial for normal liver physiology and the pathogenesis of liver diseases. During the last decade, the function of autophagy in hepatocellular carcinoma (HCC) has been evaluated extensively. Currently, autophagy is thought to play a dual role in HCC, i.e., autophagy is involved in tumorigenesis and tumor suppression. Recent investigations of autophagy have suggested that autophagy biomarkers can facilitate HCC prognosis and the establishment of therapeutic approaches. In this review, we briefly summarize the current understanding of autophagy and discuss recent evidence for its role in HCC.

Autophagy Protects against CYP2E1/Chronic Ethanol-Induced Hepatotoxicity

Autophagy is an intracellular pathway by which lysosomes degrade and recycle long-lived proteins and cellular organelles. The effects of ethanol on autophagy are complex but recent studies have shown that autophagy serves a protective function against ethanol-induced liver injury. Autophagy was found to also be protective against CYP2E1-dependent toxicity in vitro in HepG2 cells which express CYP2E1 and in vivo in an acute alcohol/CYPE1-dependent liver injury model. The goal of the current report was to extend the previous in vitro and acute in vivo experiments to a chronic ethanol model to evaluate whether autophagy is also protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. Wild type (WT), CYP2E1 knockout (KO) or CYP2E1 humanized transgenic knockin (KI), mice were fed an ethanol liquid diet or control dextrose diet for four weeks. In the last week, some mice received either saline or 3-methyladenine (3-MA), an inhibitor of autophagy, or rapamycin, which stimulates autophagy. Inhibition of autophagy by 3-MA potentiated the ethanol-induced increases in serum transaminase and triglyceride levels in the WT and KI mice but not KO mice, while rapamycin prevented the ethanol liver injury. Treatment with 3-MA enhanced the ethanol-induced fat accumulation in WT mice and caused necrosis in the KI mice; little or no effect was found in the ethanol-fed KO mice or any of the dextrose-fed mice. 3-MA treatment further lowered the ethanol-decrease in hepatic GSH levels and further increased formation of TBARS in WT and KI mice, whereas rapamycin blunted these effects of ethanol. Neither 3-MA nor rapamycin treatment affected CYP2E1 catalytic activity or content or the induction CYP2E1 by ethanol. The 3-MA treatment decreased levels of Beclin-1 and Atg 7 but increased levels of p62 in the ethanol-fed WT and KI mice whereas rapamycin had the opposite effects, validating inhibition and stimulation of autophagy, respectively. These results suggest that autophagy is protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. We speculate that autophagy-dependent processes such as mitophagy and lipophagy help to minimize ethanol-induced CYP2E1-dependent oxidative stress and therefore the subsequent liver injury and steatosis. Attempts to stimulate autophagy may be helpful in lowering ethanol and CYP2E1-dependent liver toxicity.

Increased Autophagy Markers Are Associated with Ductular Reaction during the Development of Cirrhosis

Autophagy is a regulatory pathway in liver fibrosis. We investigated the roles of autophagy in human cirrhotic livers. Cirrhotic and noncirrhotic liver tissues were obtained from patients with hepatocellular carcinoma, and liver tissues from live donors served as control. Patients with cirrhotic livers had significantly increased levels of various essential autophagy-related genes compared with noncirrhotic livers. In addition, colocalization of autophagy marker microtubule-associated protein 1 light chain 3B (LC3B) with lysosome-associated membrane protein-1, increased levels of lysosome-associated membrane protein-2, and increased maturation of lysosomal cathepsin D were observed in cirrhotic livers. By using dual-immunofluorescence staining, we demonstrated that increased LC3B was located mainly in the cytokeratin 19-labeled ductular reaction (DR) in human cirrhotic livers and in an experimental cirrhosis induced by 2-acetylaminofluorene (AAF) with carbon tetrachloride (CCl4), indicating a conserved response to chronic liver damage. Furthermore, an AAF/CCl4-mediated increase in DR and fibrosis were attenuated after chloroquine treatment, suggesting that the autophagy-lysosome pathway was essential for AAF/CCl4-induced DR-fibrosis. In conclusion, we demonstrated that increased autophagy marker positively correlated with DR during the development of cirrhosis. Therefore, targeting autophagy may hold therapeutic value for liver cirrhosis.

Mechanisms of fibrosis in acute liver failure

BACKGROUND & AIMS

Acute liver failure (ALF) is a condition with high mortality and morbidity. Fibrosis in chronic liver disease was extensively researched, whereas fibrosis and underlying mechanism in acute liver failure remains unclear.

METHODS

Hepatitis B virus related ALF patients were recruited to investigate if there was ongoing fibrosis by liver histology and liver stiffness measurement(LSM) analysis as well as fibrosis markers assay. Sera HMGB1 were kinetically detected in progression and remission stage of ALF. Hepatic stellate cell(HSC) activation by HMGB1 was explored by testing mRNA and protein level of α-SMA and collagen 1a1 by using qPCR and western blot. Autophagy induction by HMGB1 was explored by LC3-II conversion, autophagy flux and fluorescence.

RESULTS

Firstly, ongoing fibrosis in progression stage of ALF was confirmed by histological analysis, LS measurement as well as fibrosis markers detection. HSC activation and autophagy induction in explanted liver tissue also revealed. Next, kinetic monitoring sera HMGB1 revealed elevated HMGB1 in progression stage of ALF vs HBsAg carrier, and drop back to base level in remission stage. Thirdly, rHMGB1 dose dependently activated HSCs, as indicated by increased mRNA and proteins level in α-SMA and collagen 1a1. Moreover, autophagy was induced in HSC treated with rHMGB1, as illustrated by increased LC3 lipidation, elevated autophagy flux and GFP-LC3 puncta.

CONCLUSIONS

Acute liver failure is accompanied by ongoing fibrosis, HSC activation and autophagy induction. Increased HMGB1 activates HSC via autophagy induction. Those findings integrate HMGB1, HSCs activation, autophagy into a common framework that underlies the fibrosis in ALF.

Physical exercise antagonizes clinical and anatomical features characterizing Lieber-DeCarli diet-induced obesity and related metabolic disorders

BACKGROUND & AIMS

Lieber-DeCarli diet has been used to induce obesity and non-alcoholic steatohepatitis (NASH). As scarce anatomical and clinical-related information on this diet model exists and being exercise an advised strategy to counteract metabolic diseases, we aimed to analyze the preventive (voluntary physical activity - VPA) and therapeutic (endurance training - ET) effect of exercise on clinical/anatomical features of rats fed with Lieber-DeCarli diet.

METHODS

In the beginning of the protocol, Sprague-Dawley rats were divided into standard-diet sedentary (SS, n = 20), standard-diet VPA (SVPA, n = 10), high-fat diet sedentary (HS, n = 20) and high-fat diet VPA (HVPA, n = 10) groups. After 9-weeks, half (n = 10) of SS and HS groups were engaged in an ET program (8 wks/5 d/wk/60 min/day). At this time, a blood sample was collected for biochemical analysis. At the end of protocol (17-weeks) anatomic measures were assessed. Heart, liver, femur and visceral fat were weighted and blood was collected again. Liver section was used for histopathological examination.

RESULTS

At 17-weeks, high-fat diet increased visceral adiposity (HS vs. SS), which was counteracted by both exercises. However, ET was the only intervention able to diminished obesity-related measures and the histological features of NASH. Moreover, blood analysis at 9 weeks showed that high-fat diet increased ALT, AST, cholesterol and HDL while VLDL and TG levels were decreased (HS vs. SS). Notably, although these parameters were counteracted after 9-weeks of VPA, they were transitory and not observed after 17-weeks.

CONCLUSIONS

ET used as a therapeutic tool mitigated the clinical/anatomical-related features induced by Liber-DeCarli diet, thus possibly contributing to control obesity and metabolic disorders.

Hepatocyte autophagy is linked to C/EBP-homologous protein, Bcl2-interacting mediator of cell death, and BH3-interacting domain death agonist gene expression

BACKGROUND

Endoplasmic reticulum (ER) stress and autophagy each play important roles in hepatocyte cell injury. We hypothesized that gene expression of C/EBP-homologous protein (CHOP) and the BH3 proteins Bcl2-interacting mediator of cell death (BIM) and BH3-interacting domain death agonist (BID) are involved in a complex interplay that regulates ER stress-induced autophagy and cell death.

MATERIALS AND METHODS

Hepatocytes were cultured from lean Zucker rats. Confluent hepatocytes were incubated with single or combined small interfering RNA for CHOP, BIM, and/or BID for 24 h providing gene inhibition. Incubation with tunicamycin (TM) for another 24 h stimulated ER stress. Quantitative real-time polymerase chain reaction determined the expression levels of CHOP, BIM, and BID. Immunostaining with microtubule-associated protein 1 light chain 3 measured autophagy activity. Trypan blue exclusion determined the cell viability.

RESULTS

TM treatment increased the messenger RNA levels of CHOP and BIM but decreased the messenger RNA levels of BID. TM increased autophagy and decreased cell viability. Individual inhibition of CHOP, BIM, or BID protected against autophagy and cell death. However, simultaneous treatment with any combination of CHOP, BIM, and BID small interfering RNAs reduced autophagy activity but increased cell death independent of ER stress induction.

CONCLUSIONS

Autophagy in hepatocytes results from acute ER stress and involves interplay, at the gene expression level, of CHOP, BIM, and BID. Inhibition of any one of these individual genes during acute ER stress is protective against cell death. Conversely, inhibition of any two of the three genes results in increased nonautophagic cell death independent of ER stress induction. This study suggests interplay between CHOP, BIM, and BID expression that can be leveraged for protection against ER stress-related cell death. However, disruption of the CHOP/BH3 gene expression homeostasis is detrimental to cell survival independent of other cellular stress.

Elucidating mechanisms of toxicity using phenotypic data from primary human cell systems--a chemical biology approach for thrombosis-related side effects

Here we describe a chemical biology approach for elucidating potential toxicity mechanisms for thrombosis-related side effects. This work takes advantage of a large chemical biology data set comprising the effects of known, well-characterized reference agents on the cell surface levels of tissue factor (TF) in a primary human endothelial cell-based model of vascular inflammation, the BioMAP^® 3C system. In previous work with the Environmental Protection Agency (EPA) for the ToxCast™ program, aryl hydrocarbon receptor (AhR) agonists and estrogen receptor (ER) antagonists were found to share an usual activity, that of increasing TF levels in this system. Since human exposure to compounds in both chemical classes is associated with increased incidence of thrombosis-related side effects, we expanded this analysis with a large number of well-characterized reference compounds in order to better understand the underlying mechanisms. As a result, mechanisms for increasing (AhR, histamine H1 receptor, histone deacetylase or HDAC, hsp90, nuclear factor kappa B or NFκB, MEK, oncostatin M receptor, Jak kinase, and p38 MAPK) and decreasing (vacuolar ATPase or V-ATPase) and mTOR) TF expression levels were uncovered. These data identify the nutrient, lipid, bacterial, and hypoxia sensing functions of autophagy as potential key regulatory points controlling cell surface TF levels in endothelial cells and support the mechanistic hypothesis that these functions are associated with thrombosis-related side effects in vivo.

Effect of Golgi phosphoprotein 2 (GOLPH2/GP73) on autophagy in human hepatocellular carcinoma HepG2 cells

This study aims to investigate the effect of Golgi Protein 73 (GP73) on autophagy in human hepatoma line cells HepG2. We investigated the functional effects of GP73 on autophagy in hepatoma cell line HepG2 using immunofluoscence staining, Western blotting and real-time PCR. Our data showed that specific small interference RNA (siRNA) notably induced formation of autophagic vacuoles. In addition, upregulation of GP73 significantly inhibited formation of starvation-induced LC3-positive structures. We provide the first experimental evidence to show that GP73 may play an important role in the inhibitory regulation of autophagy. Therefore, our data suggest a new molecular mechanism for GP73-related hepatoma progression.

The association between impaired autophagy and the development of congenital ureteropelvic junction obstruction

OBJECTIVE

To investigate the association between impaired autophagy in smooth muscle cells and the development of congenital ureteropelvic junction (UPJ) obstruction (UPJO).

MATERIALS AND METHODS

Tissue specimens were obtained from 40 patients with unilateral UPJO and were divided into 3 sections as renal pelvis, site of obstruction, and the ureter distal to obstruction. Control specimens were obtained from the UPJ of 40 age-matched cadavers. Autophagy was evaluated by image analysis techniques for the expression of light chain 3 (LC3) after immunohistochemical staining of LC3 rabbit polyclonal antibody and Western blot analysis; additionally, myocyte apoptosis was determined using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, 4',6-diamidino-2-phenylindole staining, and p53 immunohistochemical staining. To assess the possible role of cell senescence, P21 and P16 immunohistochemistry staining was applied. Cellular proliferation was assessed by image analysis of proliferating cell nuclear antigen-stained specimens.

RESULTS

LC3 expression was significantly increased at the renal pelvis (P <.05). Apoptotic indices of smooth muscle cells and Bcl-2 were significantly greater at the site of UPJO (5.15 ± 0.91) compared with the UPJs of the control group (P <.001). A significant negative correlation was found between TUNEL and LC3 in all sections of the obstructed UPJ complex (P <.05). Proliferating cell nuclear antigen and LC3 were positively correlated in the renal pelvis and UPJ (P <.05); however, no specimen was stained for p16, p21, and p53.

CONCLUSION

In conclusion, impaired autophagy is associated with the development of congenital UPJO. Nonetheless, further studies are mandated to establish its etiologic role.

Hypoxia-inducible factor-1alpha regulates autophagy to activate hepatic stellate cells

The role of autophagy in Hif-1α modulated activation of hepatic stellate cells was illustrated in current work. Autophagy markers were determined in livers of Schistosoma japonicum infected mice and hypoxia or LPS treated human hepatic stellate cell, LX-2 cells. The action of Hif-1 to autophagy was defined as increase of autophagy markers was significantly suppressed in Hif-1α siRNA transfected cells upon hypoxia or LPS stimulation. The function of autophagy in activation of LX-2 cells was assessed as increase of activation markers was blocked using autophagy inhibitors under hypoxia and LPS stimulation. Conclusively, Hif-1α regulates activation of hepatic stellate cell by modulating autophagy.

Transforming growth factor‑β1 reduces apoptosis via autophagy activation in hepatic stellate cells

Autophagy is a metabolic process that is important in fibrogenesis, in which cellular components are degraded by lysosomal machinery. Transforming growth factor β1 (TGF‑β1) is a potent fibrogenic cytokine involved in liver fibrosis; however, it remains elusive whether autophagy is regulated by TGF‑β1 in this process. In the present study, the function of TGF‑β1‑mediated autophagy in the proliferation and apoptosis of hepatic stellate cells (HSCs) was investigated. A rat HSC cell line (HSC‑T6) was incubated with or without TGF‑β1 followed by bafilomycin A1, and microtubule-associated proteins 1A/1B light chain 3 (LC3) small interfering (si)RNA was used to inhibit autophagy in order to assess the association between TGF‑β1 and autophagy. HSC‑T6 cell transient transfection was accomplished with a pLVX‑AcGFP‑N1‑rLC3B‑encoding plasmid. An MTS assay and flow cytometry were utilized to detect proliferation and apoptosis of HSC‑T6 cells. Quantitative polymerase chain reaction, immunofluorescence and western blot analysis were used to detect the presence of activation markers. Proliferation was increased and apoptosis was reduced in HSC‑T6 cells treated with TGF‑β1 compared with cells subjected to serum deprivation. However, when HSC‑T6 cells were treated with bafilomycin A1 and LC3 siRNA, increased apoptosis and reduced proliferation were observed. In addition, protein and mRNA expression levels of the autophagy marker LC3 were significantly increased. GFP‑LC3 punctate markings were more prolific following TGF‑β1 treatment of HSC‑T6 cells, indicating that TGF‑β1 may rescue HSC‑T6 cells from serum deprivation and reduce apoptosis via autophagy induction. The present study elucidated the possible functions of TGF‑β1‑mediated autophagy in the pathological process of liver fibrosis.

Toll-Like Receptor 4 Knockout Protects Against Isoproterenol-Induced Cardiac Fibrosis

Background:

Toll-like receptor 4 participates in the process of acute heart injury. The underlying mechanisms of its protection are multifactorial, but we hypothesized that toll-like receptor-mediated autophagy control plays a vital role. The purpose of this study was to clarify the effect of autophagy on cardiac fibrosis.

Methods:

Cardiac fibrosis was induced by subcutaneous isoproterenol (ISO) injection, and rapamycin was simultaneously administered orally for 14 days. Animal echocardiography was then used to evaluate the success of the cardiac fibrosis model, and the mice were killed after the echocardiography examination.

Results:

Toll-like receptor 4 knockout (TLR4 KO) mice had better heart function than did wild-type (WT) mice ( P < .05). Rapamycin treatment reduced the left ventricular ejection fraction to 23.5% ( P < .05), and the collagen volume fraction of the ISO and ISO plus rapamycin groups was 5.9% and 25.9%, respectively, in TLR4 KO mice. Compared with the WT mice, Beclin 1 and autophagy were downregulated in TLR4 KO mice ( P < .05); however, the ISO plus rapamycin group had higher autophagy activity than did the ISO group in TLR4 KO mice ( P < .05).

Conclusions:

Our results suggest that TLR4 KO-induced cardioprotection against ISO-induced cardiac fibrosis is associated with reduced autophagy induction. Cardiac fibroblast autophagy participates in its own activation. The moderate inhibition of autophagic activity may be a new strategy for treating cardiac fibrosis.

Sodium orthovanadate inhibits growth of human hepatocellular carcinoma cells in vitro and in an orthotopic model in vivo

The transition metal vanadium is widely distributed in the environment and exhibits various biological and physiological effects in the human body. As a well known vanadium compound, sodium orthovanadate (SOV) has shown promising antineoplastic activity in several human cancers. However, the effects of SOV on liver cancer are still unknown. In this study, for the first time, we showed that SOV could effectively suppress proliferation, induce G2/M cell cycle arrest and apoptosis, and diminish the mitochondrial membrane potential (MMP) of HCC cells in vitro. In addition, our in vitro results were recapitulated in vivo, showing that SOV exhibited a dose-dependent inhibition of growth of human HCC in an orthotopic model, evidenced by the reduction in tumor size, proliferation index and microvessel density, and increase in cell apoptosis. Most important, we found that SOV could inhibit autophagy in HCC cells in vitro and in vivo, which plays a prodeath role. Thus, our findings suggest that SOV could effectively suppress the growth of human HCC through the regulations of proliferation, cell cycle, apoptosis and autophagy, and thus may act as a potential therapeutic agent in HCC treatment.

Biomarkers of liver cell death

Hepatocyte cell death during liver injury was classically viewed to occur by either programmed (apoptosis), or accidental, uncontrolled cell death (necrosis). Growing evidence from our increasing understanding of the biochemical and molecular mechanisms involved in cell demise has provided an expanding view of various modes of cell death that can be triggered during both acute and chronic liver damage such as necroptosis, pyroptosis, and autophagic cell death. The complexity of non-invasively assessing the predominant mode of cell death during a specific liver insult in either experimental in vivo models or in humans is highlighted by the fact that in many instances there is significant crosstalk and overlap between the different cell death pathways. Nevertheless, the realization that during cell demise triggered by a specific mode of cell death certain intracellular molecules such as proteins, newly generated protein fragments, or MicroRNAs are released from hepatocytes into the extracellular space and may appear in circulation have spurred a significant interest in the development of non-invasive markers to monitor liver cell death. This review focuses on some of the most promising markers, and their potential role in assessing the presence and severity of liver damage in humans.

Caffeine stimulates hepatic lipid metabolism by the autophagy-lysosomal pathway in mice

Caffeine is one of the world's most consumed drugs. Recently, several studies showed that its consumption is associated with lower risk for nonalcoholic fatty liver disease (NAFLD), an obesity-related condition that recently has become the major cause of liver disease worldwide. Although caffeine is known to stimulate hepatic fat oxidation, its mechanism of action on lipid metabolism is still not clear. Here, we show that caffeine surprisingly is a potent stimulator of hepatic autophagic flux. Using genetic, pharmacological, and metabolomic approaches, we demonstrate that caffeine reduces intrahepatic lipid content and stimulates β-oxidation in hepatic cells and liver by an autophagy-lysosomal pathway. Furthermore, caffeine-induced autophagy involved down-regulation of mammalian target of rapamycin signaling and alteration in hepatic amino acids and sphingolipid levels. In mice fed a high-fat diet, caffeine markedly reduces hepatosteatosis and concomitantly increases autophagy and lipid uptake in lysosomes.

CONCLUSION

These results provide novel insight into caffeine's lipolytic actions through autophagy in mammalian liver and its potential beneficial effects in NAFLD.