Mitochondrial stress in advanced fibrosis and cirrhosis associated with chronic hepatitis B, chronic hepatitis C, or nonalcoholic steatohepatitis.

BACKGROUND AND AIMS: Hepatitis B virus (HBV) infection causes oxidative stress (OS) and alters mitochondria in experimental models. Our goal was to investigate whether HBV might alter liver mitochondria also in humans, and the resulting mitochondrial stress might account for the progression of fibrosis in chronic hepatitis B (CHB). APPROACH AND RESULTS: The study included 146 treatment-naïve CHB mono-infected patients. Patients with CHB and advanced fibrosis (AF) or cirrhosis (F3-F4) were compared to patients with no/mild-moderate fibrosis (F0-F2). Patients with CHB were further compared to patients with chronic hepatitis C (CHC; n = 33), nonalcoholic steatohepatatis (NASH; n = 12), and healthy controls ( n = 24). We detected oxidative damage to mitochondrial DNA (mtDNA), including mtDNA strand beaks, and identified multiple mtDNA deletions in patients with F3-F4 as compared to patients with F0-F2. Alterations in mitochondrial function, mitochondrial unfolded protein response, biogenesis, mitophagy, and liver inflammation were observed in patients with AF or cirrhosis associated with CHB, CHC, and NASH. In vitro , significant increases of the mitochondrial formation of superoxide and peroxynitrite as well as mtDNA damage, nitration of the mitochondrial respiratory chain complexes, and impairment of complex I occurred in HepG2 cells replicating HBV or transiently expressing hepatitits B virus X protein. mtDNA damage and complex I impairment were prevented with the superoxide-scavenging Mito-Tempo or with inducible nitric oxide synthase (iNOS)-specific inhibitor 1400 W. CONCLUSIONS: Our results emphasized the importance of mitochondrial OS, mtDNA damage, and associated alterations in mitochondrial function and dynamics in AF or cirrhosis in CHB and NASH. Mitochondria might be a target in drug development to stop fibrosis progression.

New therapies for hepatitis delta virus infection.

Hepatitis delta virus (HDV) infection is a defective virus requiring hepatitis B virus (HBV) for its complete replication cycle. HDV is a small hepatotropic RNA virus and around 15 to 25 million people worldwide are living with chronic hepatitis delta (CHD) infection. However, the prevalence of HDV may be underestimated, and screening is frequently insufficient. HDV infection remains endemic in several regions including Central and West Africa, the Mediterranean basin, the Middle East, Eastern Europe, Northern Asia, certain areas of Southeast Asia and the Amazon basin of South America. The best preventive strategy to decrease HDV infection is to improve coverage of the prophylactic HBV vaccine. HDV infection may occur by HBV-HDV co-infection or superinfection, and the latter is usually more severe. CHD is associated with a higher risk of cirrhosis and hepatocellular carcinoma (HCC) compared to HBV mono-infection. Pegylated interferon alpha (PEG-IFNα) therapy is limited by moderate effectiveness (around 20%) and its adverse effects. The entry inhibitor, bulevirtide (BLV, Hepcludex® ), which was recently approved in Europe at a dose of 2 mg in sub-cutaneous injection per day, is indicated for the treatment of CHD in adult patients with compensated liver disease and positive HDV viremia. BLV can be administrated in monotherapy or in combination with PEG-IFNα. Nucleos(t)ide analogues can be used in combination for underlying HBV infection. The optimal treatment duration has not yet been determined and treatment should be continued if a clinical benefit is observed. There are other promising therapies such as IFN lambda (IFNλ) (immunomodulator), lonafarnib (prenylation inhibitor) and nucleic acid polymers (Inhibitors of HBsAg release). In this review, we will present an update on CHD and future promising treatments.

Early virological response in six patients with hepatitis D virus infection and compensated cirrhosis treated with Bulevirtide in real-life.

Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. Bulevirtide (BLV, Hepcludex® ) is an HDV/HBV entry inhibitor approved in June 2020 in the European Union for adult patients with chronic hepatitis delta (CHD) and compensated liver disease and positive HDV RNA viral load. This real-life preliminary report described early virological efficacy and safety of BLV in six patients with CHD and compensated liver disease: four patients were treated with the combination of BLV (2 mg/d in subcutaneous injection) and pegylated interferon (PEG-IFN) and two patients with BLV monotherapy. Four patients treated with combined therapy had a decline of a minimum of 1 log10 and 3/3 of 2 log10 of HDV-VL at 12 and 24 weeks, respectively. One patient among four had stopped the treatment at 12 weeks because of thrombocytopenia and an HDV-VL relapse was notified 24 weeks after treatment cessation. Three patients among four (3/4) had undetectable HDV-VL during the therapy (<100 IU/ml). One patient (1/2) treated with BLV monotherapy had a decline of HDV-VL by 1 log10 at 8 weeks and 1/1 by 2 log10 at 28 week on-treatment. Two patients among four (2/4) with combined therapy had normal ALT reached at 4 and 56 weeks. One patient (1/2) with BLV monotherapy achieves ALT normalization at​ 4 weeks on treatment. Hepatitis B surface antigen (HBsAg) levels remain unchanged. Three among six (3/6) patients had an elevation of total biliary acids without pruritus. These early data generated confirm the interest in this new treatment. Final results will be important to demonstrate long-term clinical benefit (fibrosis reversibility and reduction in hepato-cellular carcinoma [HCC]).

Hepatitis B surface antigen seroclearance: Immune mechanisms, clinical impact, importance for drug development.

HBsAg seroclearance occurs rarely in the natural history of chronic hepatitis B (CHB) infection and is associated with improved clinical outcomes. Many factors are associated with HBsAg seroconversion, including immune and viral factors. However, the immune mechanisms associated with HBsAg seroclearance are still difficult to elucidate. HBsAg seroclearance is the ideal aim of HBV treatment. Unfortunately, this goal is rarely achieved with current treatments. Understanding the mechanisms of HBsAg loss appears to be important for the development of curative HBV treatments. While studies from animal models give insights into the potential immune mechanisms and interactions occurring between the immune system and HBsAg, they do not recapitulate all features of CHB in humans and are subject to variability due to their complexity. In this article, we review recent studies on these immune factors, focusing on their influence on CHB progression and HBsAg seroconversion. These data provide new insights for the development of therapeutic approaches to partially restore the anti-HBV immune response. Targeting HBsAg will ideally relieve the immunosuppressive effects on the immune system and help to restore anti-HBV immune responses.

Future treatments for hepatitis delta virus infection.

Around 15-20 million people develop chronic hepatitis delta virus worldwide. Hepatitis delta virus (HDV) is a defective RNA virus requiring the presence of the hepatitis B virus surface antigen (HBsAg) to complete its life cycle. HDV infects hepatocytes using the hepatitis B virus (HBV) receptor, the sodium taurocholate cotransporting polypeptide (NTCP). The HDV genome is a circular single-stranded RNA which encodes for a single hepatitis delta antigen (HDAg) that exists in two forms (S-HDAg and L-HDAg), and its replication is mediated by the host RNA polymerases. The HBsAg-coated HDV virions contain a ribonucleoprotein (RNP) formed by the RNA genome packaged with small and large HDAg. Farnesylation of the L-HDAg is the limiting step for anchoring this RNP to HBsAg, and thus for assembling, secreting and propagating virion particles. There is an important risk of morbidity and mortality caused by end-stage liver disease and hepatocellular carcinoma with HDV and current treatment is pegylated-interferon (PEG-IFN) for 48 weeks with no other options in patients who fail treatment. The ideal goal for HDV treatment is the clearance of HBsAg, but a reasonably achievable goal is a sustained HDV virological response (negative HDV RNA 6 months after stopping treatment). New drug development must take into account the interaction of HBV and HDV. In this review, we will present the new insights in the HDV life cycle that have led to the development of novel classes of drugs and discuss antiviral approaches in phase II and III of development: bulevirtide (entry inhibitor), lonafarnib, (prenylation inhibitor) and REP 2139 (HBsAg release inhibitor).

Inhibition of monoacylglycerol lipase, an anti-inflammatory and antifibrogenic strategy in the liver.

OBJECTIVE: Sustained inflammation originating from macrophages is a driving force of fibrosis progression and resolution. Monoacylglycerol lipase (MAGL) is the rate-limiting enzyme in the degradation of monoacylglycerols. It is a proinflammatory enzyme that metabolises 2-arachidonoylglycerol, an endocannabinoid receptor ligand, into arachidonic acid. Here, we investigated the impact of MAGL on inflammation and fibrosis during chronic liver injury. DESIGN: C57BL/6J mice and mice with global invalidation of MAGL (MAGL -/- ), or myeloid-specific deletion of either MAGL (MAGLMye-/-), ATG5 (ATGMye-/-) or CB2 (CB2Mye-/-), were used. Fibrosis was induced by repeated carbon tetrachloride (CCl4) injections or bile duct ligation (BDL). Studies were performed on peritoneal or bone marrow-derived macrophages and Kupffer cells. RESULTS: MAGL -/- or MAGLMye-/- mice exposed to CCl4 or subjected to BDL were more resistant to inflammation and fibrosis than wild-type counterparts. Therapeutic intervention with MJN110, an MAGL inhibitor, reduced hepatic macrophage number and inflammatory gene expression and slowed down fibrosis progression. MAGL inhibitors also accelerated fibrosis regression and increased Ly-6Clow macrophage number. Antifibrogenic effects exclusively relied on MAGL inhibition in macrophages, since MJN110 treatment of MAGLMye-/- BDL mice did not further decrease liver fibrosis. Cultured macrophages exposed to MJN110 or from MAGLMye-/- mice displayed reduced cytokine secretion. These effects were independent of the cannabinoid receptor 2, as they were preserved in CB2Mye-/- mice. They relied on macrophage autophagy, since anti-inflammatory and antifibrogenic effects of MJN110 were lost in ATG5Mye-/- BDL mice, and were associated with increased autophagic flux and autophagosome biosynthesis in macrophages when MAGL was pharmacologically or genetically inhibited. CONCLUSION: MAGL is an immunometabolic target in the liver. MAGL inhibitors may show promising antifibrogenic effects during chronic liver injury.

Mitochondrial Dysfunction and Signaling in Chronic Liver Diseases.

Mitochondria regulate hepatic lipid metabolism and oxidative stress. Ultrastructural mitochondrial lesions, altered mitochondrial dynamics, decreased activity of respiratory chain complexes, and impaired ability to synthesize adenosine triphosphate are observed in liver tissues from patients with alcohol-associated and non-associated liver diseases. Increased lipogenesis with decreased fatty acid ß-oxidation leads to the accumulation of triglycerides in hepatocytes, which, combined with increased levels of reactive oxygen species, contributes to insulin resistance in patients with steatohepatitis. Moreover, mitochondrial reactive oxygen species mediate metabolic pathway signaling; alterations in these pathways affect development and progression of chronic liver diseases. Mitochondrial stress and lesions promote cell death, liver fibrogenesis, inflammation, and the innate immune responses to viral infections. We review the involvement of mitochondrial processes in development of chronic liver diseases, such as nonalcoholic fatty, alcohol-associated, and drug-associated liver diseases, as well as hepatitis B and C, and discuss how they might be targeted therapeutically.

GLRX5 mutations impair heme biosynthetic enzymes ALA synthase 2 and ferrochelatase in Human congenital sideroblastic anemia.

Non-syndromic microcytic congenital sideroblastic anemia (cSA) is predominantly caused by defective genes encoding for either ALAS2, the first enzyme of heme biosynthesis pathway or SLC25A38, the mitochondrial importer of glycine, an ALAS2 substrate. Herein we explored a new case of cSA with two mutations in GLRX5, a gene for which only two patients have been reported so far. The patient was a young female with biallelic compound heterozygous mutations in GLRX5 (p.Cys67Tyr and p.Met128Lys). Three-D structure analysis confirmed the involvement of Cys67 in the coordination of the [2Fe2S] cluster and suggested a potential role of Met128 in partner interactions. The protein-level of ferrochelatase, the terminal-enzyme of heme process, was increased both in patient-derived lymphoblastoid and CD34+ cells, however, its activity was drastically decreased. The activity of ALAS2 was found altered and possibly related to a defect in the biogenesis of its co-substrate, the succinyl-CoA. Thus, the patient exhibits both a very low ferrochelatase activity without any accumulation of porphyrins precursors in contrast to what is reported in erythropoietic protoporphyria with solely impaired ferrochelatase activity. A significant oxidative stress was evidenced by decreased reduced glutathione and aconitase activity, and increased MnSOD protein expression. This oxidative stress depleted and damaged mtDNA, decreased complex I and IV activities and depleted ATP content. Collectively, our study demonstrates the key role of GLRX5 in modulating ALAS2 and ferrochelatase activities and in maintaining mitochondrial function.

Eliminating hepatitis C within low-income countries - The need to cure genotypes 4, 5, 6.

Around 70 to 100 million people are chronically infected with HCV worldwide. HCV antiviral drug development has revolutionised the treatment of HCV, with several direct-acting antiviral agents offering patients the chance of cure after only 8-12 weeks of treatment. Drug development was initially focussed on HCV genotype 1 (GT1) infection, since this was the most prevalent worldwide, although clinical trials included all genotypes prevalent in the US and Europe. Because the earliest in vitro assays utilised the GT1b and 2 replicons, the initial classes of direct-acting antivirals (protease inhibitors, non-nucleotide polymerase inhibitors) were GT1-specific, albeit they had an effect on other less prevalent genotypes. Epidemiological data has shown the regional importance of other HCV genotypes. More than 50% of all HCV infections around the globe are not with GT1. The prevalence of HCV genotype 4 (GT4), 5 (GT5), and 6 (GT6) is increasing in North America and Europe due to migration from the Middle East, Africa and South-East Asia. With the successful development of the multi and pan-genotypic non-structural protein 5A inhibitors, second generation protease inhibitors and nucleotide non-structural protein 5B inhibitors comes a unique opportunity to achieve global HCV elimination. The goal of this review is to summarise the available information pertaining to GT4, GT5 and GT6, with a specific focus on direct-acting antiviral agents.

Impact of cytokine gene variants on the prediction and prognosis of hepatocellular carcinoma in patients with cirrhosis.

BACKGROUND & AIMS: Genetic polymorphisms modulate the expression of proinflammatory cytokines. We prospectively assessed the influence of 6 single nucleotide polymorphisms (SNPs) in TNFα, IL6, and IL1ß genes on the risk of hepatocellular carcinoma (HCC) in patients with cirrhosis. METHODS: TNFα (G-238A, C-863A, G-308A), IL6 (C-174G), and IL1ß (C-31T, C-511T) SNPs were assessed in 232 alcoholics and 253 HCV-infected patients with biopsy-proven cirrhosis, prospectively followed-up and screened for HCC. Their influence on HCC development was assessed using the Kaplan-Meier method. RESULTS: These variants did not influence the risk of HCC in alcoholic patients. Conversely, two variants influenced the risk of HCC occurrence in patients with HCV-related cirrhosis, namely the TNFα-308 (A) allele (HR = 2.4 [1.6-3.7], Log-rank <0.0001) and the IL1ß-31 (T) allele (HR = 1.5 [1.1-2.1], Log-rank = 0.004). When stratifying HCV-infected patients into four genotypic associations expected to progressively increase TNFα and IL1ß production, we observed increasing risk of HCC occurrence (Log-rank <0.0001) from group 1 to 4. The TNFα-308 (A) allele was the only genetic trait independently associated with risk of HCC in these patients, along with older age, male gender, BMI, and platelet count. These variables led to construction of a predictive score able to separate patients with HCV-related cirrhosis into three subgroups with progressively increasing 5-year cumulative incidences of 4.7%, 14.1%, and 36.3%, respectively (Log-rank <0.0001). CONCLUSIONS: Genetic heterogeneity in the TNFα and IL1ß gene promoters influences the risk of HCC in patients with HCV-induced cirrhosis. These genetic data, when incorporated into clinical scores, are able to refine selection of risk classes of HCC.

PNPLA3 rs738409, hepatocellular carcinoma occurrence and risk model prediction in patients with cirrhosis.

BACKGROUND & AIMS: Several studies have reported an association between the genetic variant rs738409 (G) in the PNPLA3 gene and the risk of cirrhosis in various liver diseases. Our purpose was to assess the influence of this polymorphism on the risk of hepatocellular carcinoma (HCC) occurrence in two distinct longitudinal cohorts of patients with cirrhosis as well as its possible usefulness in HCC-risk model prediction. METHODS: PNPLA3 rs738409 genotypes were assessed in 279 patients with alcoholic- and 253 patients with HCV-related cirrhosis. These patients were followed-up and screened for the risk of HCC, and the influence of rs738409 on the occurrence of liver cancer was assessed using the Kaplan-Meier method, then according to the multivariate Cox model. RESULTS: In patients with HCV-related cirrhosis, rs738409 genotypes did not influence the risk of HCC development (log-rank = 0.7) or death (log-rank = 0.2). Conversely, in patients with alcoholic cirrhosis, the rs738409 (GG) genotype was an independent risk factor for HCC occurrence (HR = 1.72 [1.21-2.45], log-rank = 0.002) as well as older age, male gender, and higher BMI. Combining these features enabled HCC-risk stratification of this population into three groups with the 6-year cumulative incidence ranging from 3.4% (low risk, n = 58), 12.2% (intermediate risk, n = 163), and 51.7% (high risk, n = 58), respectively (HR = 4.3 [2.7-6.4]; log-rank <0.0001). CONCLUSIONS: This study provides key data that affirm the influence of the rs738409 (GG) genotype on the occurrence of HCC in patients with alcoholic cirrhosis. Its combination with clinical features refines the selection of patients at higher risk of liver cancer development.

Hepatitis-B virus: replication cycle, targets, and antiviral approaches.

An estimated 257 million people are chronic carriers of hepatitis-B virus (HBV) infection, which resulted in around 1 million deaths, mainly due to hepatocellular carcinoma (HCC). Long-term nucleotide analog treatment of HBV infection is associated with favorable prognosis, no disease progression, and a reduction of HCC risk, but lifelong treatments are required. A better understanding of HBV replication cycle and the host immune response will likely improve the identification of new targets for drug development. Studies are ongoing to determine if it is possible to successfully combine direct-acting antivirals (DAA) with an immunomodulatory therapy to allow increased cure rates. This review will start with summarizing the HBV replication cycle, recall current treatments, and then discuss potential targets and antiviral approaches in development to optimistically reach the HBV cure.

A variant in myeloperoxidase promoter hastens the emergence of hepatocellular carcinoma in patients with HCV-related cirrhosis.

BACKGROUND & AIMS: Genetic dimorphisms modulate the activities of several pro- or antioxidant enzymes, including myeloperoxidase (MPO), catalase (CAT), manganese superoxide dismutase (SOD2), and glutathione peroxidase 1 (GPx1). We assessed the role of the G(-463)A-MPO, T(-262)C-CAT, Ala16Val-SOD2, and Pro198Leu-GPx1 variants in modulating HCC development in patients with HCV-induced cirrhosis. METHODS: Two hundred and five patients with HCV-induced, biopsy-proven cirrhosis but without detectable HCC at inclusion were prospectively followed-up for HCC development. The influence of various genotypes on HCC occurrence was assessed with the Kaplan-Meier method. RESULTS: During follow-up (103.2±3.4 months), 84 patients (41%) developed HCC, and 66 died. Whereas the Ala16Val-SOD2 or Pro198Leu-GPx1 dimorphisms did not modulate the risk, HCC occurrence was increased in patients with either the homozygous GG-MPO genotype (HR=2.8 [1.7-4.4]; first quartile time to HCC occurrence: 45 vs. 96 months; LogRank <0.0001) or the homozygous CC-CAT genotype (HR=1.74 [1.06-2.82]; first quartile time to HCC occurrence: 55 vs. 96 months; LogRank=0.02). Compared to patients with neither of these two at risk factors, patients with only the CC-CAT genotype had a HR of 2.05 [0.9-4.6] (p=0.08) and patients with only the GG-MPO genotype had a HR of 3.8 [1.5-9.1] (p=0.002), while patients with both risk factors had an HR of 4.8 [2.2-10.4] (p<0.0001). However, only the GG-MPO genotype was independently associated with the HCC risk in multivariate Cox analysis. CONCLUSIONS: The high activity-associated GG-MPO genotype increases the rate of HCC occurrence in patients with HCV-induced cirrhosis.

Mitochondrial GSH determines the toxic or therapeutic potential of superoxide scavenging in steatohepatitis.

BACKGROUND & AIMS: Steatohepatitis (SH) is associated with mitochondrial dysfunction and excessive production of superoxide, which can then be converted into H(2)O(2) by SOD2. Since mitochondrial GSH (mGSH) plays a critical role in H(2)O(2) reduction, we explored the interplay between superoxide, H(2)O(2), and mGSH in nutritional and genetic models of SH, which exhibit mGSH depletion. METHODS: We used isolated mitochondria and primary hepatocytes, as well as in vivo SH models showing mGSH depletion to test the consequences of superoxide scavenging. RESULTS: In isolated mitochondria and primary hepatocytes, superoxide scavenging by SOD mimetics or purified SOD decreased superoxide and peroxynitrite generation but increased H(2)O(2) following mGSH depletion, despite mitochondrial peroxiredoxin/thioredoxin defense. Selective mGSH depletion sensitized hepatocytes to cell death induced by SOD mimetics, and this was prevented by RIP1 kinase inhibition with necrostatin-1 or GSH repletion with GSH ethyl ester (GSHee). Mice fed the methionine-choline deficient (MCD) diet or MAT1A(-/-) mice exhibited reduced SOD2 activity; in vivo treatment with SOD mimetics increased liver damage, inflammation, and fibrosis, despite a decreased superoxide and 3-nitrotyrosine immunoreactivity, effects that were ameliorated by mGSH replenishment with GSHee, but not NAC. As a proof-of-principle of the detrimental role of superoxide scavenging when mGSH was depleted transgenic mice overexpressing SOD2 exhibited enhanced susceptibility to MCD-mediated SH. CONCLUSIONS: These findings underscore a critical role for mGSH in the therapeutic potential of superoxide scavenging in SH, and suggest that the combined approach of superoxide scavenging with mGSH replenishment may be important in SH.

Central role of mitochondria in drug-induced liver injury.

A frequent mechanism for drug-induced liver injury (DILI) is the formation of reactive metabolites that trigger hepatitis through direct toxicity or immune reactions. Both events cause mitochondrial membrane disruption. Genetic or acquired factors predispose to metabolite-mediated hepatitis by increasing the formation of the reactive metabolite, decreasing its detoxification, or by the presence of critical human leukocyte antigen molecule(s). In other instances, the parent drug itself triggers mitochondrial membrane disruption or inhibits mitochondrial function through different mechanisms. Drugs can sequester coenzyme A or can inhibit mitochondrial ß-oxidation enzymes, the transfer of electrons along the respiratory chain, or adenosine triphosphate (ATP) synthase. Drugs can also destroy mitochondrial DNA, inhibit its replication, decrease mitochondrial transcripts, or hamper mitochondrial protein synthesis. Quite often, a single drug has many different effects on mitochondrial function. A severe impairment of oxidative phosphorylation decreases hepatic ATP, leading to cell dysfunction or necrosis; it can also secondarily inhibit ß-oxidation, thus causing steatosis, and can also inhibit pyruvate catabolism, leading to lactic acidosis. A severe impairment of ß-oxidation can cause a fatty liver; further, decreased gluconeogenesis and increased utilization of glucose to compensate for the inability to oxidize fatty acids, together with the mitochondrial toxicity of accumulated free fatty acids and lipid peroxidation products, may impair energy production, possibly leading to coma and death. Susceptibility to parent drug-mediated mitochondrial dysfunction can be increased by factors impairing the removal of the toxic parent compound or by the presence of other medical condition(s) impairing mitochondrial function. New drug molecules should be screened for possible mitochondrial effects.

Changes in autophagic response in patients with chronic hepatitis C virus infection.

Autophagy is a regulated process that can be involved in the elimination of intracellular microorganisms and in antigen presentation. Some in vitro studies have shown an altered autophagic response in hepatitis C virus infected hepatocytes. The present study aimed at evaluating the autophagic process in the liver of chronic hepatitis C (CHC) patients. Fifty-six CHC patients and 47 control patients (8 with nonalcoholic steatohepatitis or alcoholic liver disease, 18 with chronic heptatitis B virus infection, and 21 with no or mild liver abnormalities at histological examination) were included. Autophagy was assessed by means of electron microscopy and microtubule-associated protein light chain 3 immunoblotting. Using light chain 3 immunoblotting, the form present on autophagic vesicle (light chain 3-II) was significantly higher in CHC patients than in controls (P < 0.05). Using quantitative electron microscopy analysis, the median number of autophagic vesicles observed in hepatocytes from CHC patients was sixfold higher than in overall controls (P < 0.001). In contrast, there was no difference between CHC patients and controls in the number of mature lysosomes with electron-dense contents arguing in favor of a lack of fusion between autophagosome and lysosome. Neither genotype nor viral load influenced the autophagy level. In conclusion, autophagy is altered in hepatocytes from CHC patients, likely due to a blockade of the last step of the autophagic process.

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

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

In vivo hepatic endoplasmic reticulum stress in patients with chronic hepatitis C.

In hepatocytes, the accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and the unfolded protein response (UPR), mediated by the ER-resident stress sensors ATF-6, IRE1, and PERK. UPR-responsive genes are involved in the fate of ER-stressed cells. Cells carrying hepatitis C virus (HCV) subgenomic replicons exhibit in vitro ER stress and suggest that HCV inhibits the UPR. Since in vivo ER homeostasis is unknown in livers with chronic HCV infection, we investigated ER stress and the UPR in liver samples from untreated patients with chronic hepatitis C (CHC), in comparison with normal livers. Electron microscopy, western blotting, and real-time RT-PCR were used in liver biopsy specimens. Electron microscopy identified features showing ER stress in hepatocyte samples from patients with CHC; however, 'ER-stressed' hepatocytes were found in clusters (3-5 cells) that were scattered in the liver parenchyma. Western blot analysis confirmed the existence of hepatic ER stress by showing activation of the three ER stress sensors ATF-6, IRE1, and PERK in CHC. Real-time RT-PCR showed no significant induction of UPR-responsive genes in CHC. In contrast, genes involved in the control of diffuse processes such as liver proliferation, inflammation, and apoptosis were significantly induced in CHC. In conclusion, livers from patients with untreated CHC exhibit in vivo hepatocyte ER stress and activation of the three UPR sensors without apparent induction of UPR-responsive genes. This lack of gene induction may be explained by the inhibiting action of HCV per se (as suggested by in vitro studies) and/or by our finding of the localized nature of hepatocyte ER stress.

Toxicity Profile of the Aqueous Ethanol Root Extract of Corrigiola telephiifolia Pourr. (Caryophyllaceae) in Rodents.

Corrigiola telephiifolia Pourr. (Caryophyllaceae) is a Moroccan medicinal plant. Despite its popular usage, no study has been published concerning its toxicological profile. The acute toxicity of C. telephiifolia root extract was evaluated by giving it orally to mice at single doses of 5000, 10000, and 14000 mg/kg bodyweight. The extract was also administered at doses of 5, 70, and 2000 mg/kg bodyweight per day to rats for a forty-day toxicity study. No mortality or signs of toxicity were observed in the acute study. In the forty-day study in rats, the extract at 5 mg/kg/day showed no toxicological effects in either sex. At 70 mg/kg/day, the treated group differed from the control only by a significant decrease in serum concentrations of sodium and chloride ions (P < .05). At the dose of 2000 mg/kg/day, the extract significantly increased the serum concentrations of creatinine, alkaline phosphatase, gamma-glutamyltransferase and phosphorus (P < .05) all suggestive of functional nephrotoxicity and hepatotoxicity. The relative bodyweight of both sexes decreased at the dose of 2000 mg/kg/day, with a fast recovery for males. Histological examination did not reveal any treatment-related effects. In conclusion, Corrigiola extract appears safe at the doses used ethno-medicinally. Much higher doses pose toxicological risks.

Autophagy in liver diseases.

Autophagy, or cellular self-digestion, is a cellular pathway crucial for development, differentiation, survival, and homeostasis. Its implication in human diseases has been highlighted during the last decade. Recent data show that autophagy is involved in major fields of hepatology. In liver ischemia reperfusion injury, autophagy mainly has a prosurvival activity allowing the cell for coping with nutrient starvation and anoxia. During hepatitis B or C infection, autophagy is also increased but subverted by viruses for their own benefit. In hepatocellular carcinoma, the autophagy level is decreased. In this context, autophagy has an anti-tumor role and therapeutic strategies increasing autophagy, as rapamycin, have a beneficial effect in patients. Moreover, in hepatocellular carcinoma, Beclin-1 level, an autophagy protein, has a prognostic significance. In α-1-antitrypsin deficiency, the aggregation-prone ATZ protein accumulates in the endoplasmic reticulum. This activates the autophagic response which aims at degrading mutant ATZ. Some FDA-approved drugs which enhance autophagy and the disposal of aggregation-prone proteins may be useful in α-1-antitrypsin deficiency. Following alcohol consumption, autophagy is decreased in liver cells, likely due to a decrease in intracellular 5'-AMP-activated protein kinase (AMPk) and due to an alteration in vesicle transport in hepatocytes. This decrease in autophagy contributes to the formation of Mallory-Denk bodies and to liver cell death. Hepatic autophagy is defective in the liver in obesity and its upregulation improves insulin sensitivity.