Autophagy in hepatitis C virus-host interactions:Potential roles and therapeutic targets for liver-associated diseases

Autophagy is a lysosome-associated,degradative process that catabolizes cytosolic components to recycle nutrients for further use and maintain cell homeostasis.Hepatitis C virus(HCV)is a major cause of chronic hepatitis,which often leads to end-stage liverassociated diseases and is a significant burden on worldwide public health.Emerging lines of evidence indicate that autophagy plays an important role in promoting the HCV life cycle in host cells.Moreover,the diverse impacts of autophagy on a variety of signaling pathways in HCV-infected cells suggest that the autophagic process is required for balancing HCVhost cell interactions and involved in the pathogenesis of HCV-related liver diseases.However,the detailed molecular mechanism underlying how HCV activates autophagy to benefit viral growth is still enigmatic.Additionally,how the autophagic response contributes to disease progression in HCV-infected cells remains largely unknown.Hence,in this review,we overview the interplay between autophagy and the HCV life cycle and propose possible mechanisms by which autophagy may promote the pathogenesis of HCVassociated chronic liver diseases.Moreover,we outline the related studies on how autophagy interplays with HCV replication and discuss the possible implications of autophagy and viral replication in the progression of HCV-induced liver diseases,e.g.,steatosis and hepatocellular carcinoma.Finally,we explore the potential therapeutics that target autophagy to cure HCV infection and its related liver diseases.     

Cellular factors involved in the hepatitis C virus life cycle

The hepatitis C virus (HCV), an obligatory intracellular pathogen, highly depends on its host cells to propagate successfully. The HCV life cycle can be simply divided into several stages including viral entry, protein translation, RNA replication, viral assembly and release. Hundreds of cellular factors involved in the HCV life cycle have been identified over more than thirty years of research. Characterization of these cellular factors has provided extensive insight into HCV replication strategies. Some of these cellular factors are targets for anti-HCV therapies. In this review, we summarize the well-characterized and recently identified cellular factors functioning at each stage of the HCV life cycle.     

Electrophysiology as a tool to unravel the origin of pancreatic pain简

Intense abdominal pain is the most common symptom in chronic pancreatitis, but the underlying mechanisms are not completely understood and pain management remains a significant clinical challenge. The focus of pain origin in chronic pancreatitis traditionally has been on the pancreatic gland, assuming pain to originate in the pancreas or its surrounding organs. However, research in the last decade points to abnormal central nervous system pain processing. For this reason, electroencephalography has been receiving increasing attention. In contrast to imaging methods such as functional magnetic resonance imaging and positron emission tomography, electroencephalogram has excellent temporal resolution making it possible to investigate central processing of pain on a millisecond time scale. Moreover, continuously advancing methodology made it possible to explore brain sources responsible for generation of evoked potentials and hence to study brain reorganization due to pain in chronic pancreatitis. The aim of this review is to give an overview of the current methods and findings in electroencephalography as a tool to unravel the origin of pancreatic pain.     

Electrophysiology as a tool to unravel the origin of pancreatic pain

Intense abdominal pain is the most common symptom in chronic pancreatitis, but the underlying mechanisms are not completely understood and pain management remains a significant clinical challenge.The focus of pain origin in chronic pancreatitis traditionally has been on the pancreatic gland, assuming pain to originate in the pancreas or its surrounding organs. However, research in the last decade points to abnormal central nervous system pain processing.For this reason, electroencephalography has been receiving increasing attention. In contrast to imaging methods such as functional magnetic resonance and positron emission tomography, electroencephalogram has excellent temporal resolution making it possible to investigate central processing of pain on a millisecond time scale. Moreover, continuously advancing methodology made it possible to explore brain sources responsible for generation of evoked potentialsand hence to study brain reorganization due to pain in chronic pancreatitis. The aim of this review is to give an overview of the current methods and findings in electroencephalography as a tool to unravel the origin of pancreatic pain.     

The hepatitis C virus life cycle as a target for new antiviral therapies

The burden of disease consequent to hepatitis C virus (HCV) infection has been well described and is expected to increase dramatically over the next decade. Current approved antiviral therapies are effective in eradicating the virus in approximately 50% of infected patients. However, pegylated interferon and ribavirin-based therapy is costly, prolonged, associated with significant adverse effects, and not deemed suitable for many HCV-infected patients. As such, there is a clear and pressing need for the development of additional agents that act through alternate or different mechanisms, in the hope that such regimens could lead to enhanced response rates more broadly applicable to patients with hepatitis C infection. Recent basic science enhancements in HCV cell culture systems and replication assays have led to a broadening of our understanding of many of the mechanisms of HCV replication and, therefore, potential novel antiviral targets. In this article, we have attempted to highlight important new information as it relates to our understanding of the HCV life cycle. These steps broadly encompass viral attachment, entry, and fusion; viral RNA translation; posttranslational processing; HCV replication; and viral assembly and release. In each of these areas, we present up-to-date knowledge of the relevant aspects of that component of the viral life cycle and then describe the preclinical and clinical development targets and pathways being explored in the translational and clinical settings.     

Role of low-density lipoprotein receptor in the hepatitis C virus life cycle

Hepatitis C virus (HCV) particles are known to be in complex with lipoproteins. As a result of this interaction, the low-density lipoprotein (LDL) receptor (LDLR) has been proposed as a potential entry factor for HCV; however, its implication in virus entry remains unclear. Here, we reinvestigated the role of the LDLR in the HCV life cycle by comparing virus entry to the mechanism of lipoprotein uptake. A small interfering RNA targeting the LDLR in Huh-7 cells reduced HCV infectivity, confirming that this receptor plays a role in the life cycle of HCV generated in cell culture. However, kinetics of internalization were much faster for lipoproteins than for infectious HCV particles. Furthermore, a decrease in HCV RNA replication was observed by blocking the LDLR with a specific antibody, and this was associated with an increase in the ratio of phosphatidylethanolamine to phosphatidylcholine in host cells. Nevertheless, a soluble form of the LDLR inhibited both HCV entry into the hepatocytes and its binding to the LDLR expressed on Chinese hamster ovary cells, suggesting a direct interaction between the HCV particle and the LDLR. Finally, we showed that modification of HCV particles by lipoprotein lipase (LPL) reduces HCV infectivity and increases HCV binding to LDLR. Importantly, LPL treatment also induced an increase in RNA internalization, suggesting that LDLR, at least in some conditions, leads to nonproductive internalization of HCV. Conclusion: The LDLR is not essential for infectious HCV particle entry, whereas the physiological function of this receptor is important for optimal replication of the HCV genome.     

Paediatric and adult colonic manometry: a tool to help unravel the pathophysiology of constipation

Colonic motility subserves large bowel functions, including absorption, storage, propulsion and defaecation. Co-lonic motor dysfunction remains the leading hypothesis to explain symptom generation in chronic constipation, a heterogeneous condition which is extremely prevalent in the general population, and has huge socioeconomic impact and individual suffering. Physiological testing plays a crucial role in patient management, as it is now accepted that symptom-based assessment, although im-portant, is unsat...     

Description of a new hepatitis C risk assessment tool

BACKGROUND: Because of the low prevalence of hepatitis C virus (HCV) infection in the general population, mass screening would be expensive and of low yield. Some researchers advocate targeted screening of persons at elevated HCV risk. METHODS: This cross-sectional study aimed to develop a patient-administered tool to assess HCV infection risk. Two hundred seven patients with unknown HCV status from a general medicine practice and 222 HCV-positive patients from a hepatology practice completed a 72-item survey about demographic, social, and clinical risk factors for HCV infection. General medicine patients also underwent HCV serologic testing. RESULTS: Three (1.5%) of 207 general medicine patients had positive HCV antibody test results. These patients plus the 222 hepatology patients were significantly more likely than HCV-negative patients to report an array of factors. In a multivariable model, 7 factors remained significantly associated with HCV infection: sex with a prostitute or an injecting drug user, exposure to blood products, refusal as a blood donor or as a life insurance applicant, witnessing illicit drug use, and self-reported HBV infection. A simplified model that assigned 1 point for each factor present predicted HCV infection as well as a weighted model (based on chi(2) testing and receiver operating characteristic curve comparison). In a population with a 2% prevalence of HCV infection, people who identified 2 risk factors had a 10% chance of HCV infection, whereas those with 4 or more risk factors had a 50% chance. CONCLUSIONS: A self-administered 72-item questionnaire can stratify patients into HCV risk groups. If validated in other primary care populations, this instrument could help target HCV screening.     

Hepatitis C virus p7: molecular function and importance in hepatitis C virus life cycle and potential antiviral target

p7, a 63‐residue peptide encoded by hepatitis C virus (HCV), a major pathogen associated with a risk of developing severe liver disease, is involved in ion channel activity in lipid bilayer membranes both in in vitro and cell‐based assays. p7 protein consists of two transmembrane α‐helices, TM1 and TM2 connected by a loop oriented towards the cytoplasm. HCV relies on p7 function in addition to ion channel formation for efficient assembly, release and production of infectious progeny virions from liver cells. p7 activity is strictly sequence specific as mutation analysis showed the loss of ion channel function. Moreover, p7 ion channel activity can be specifically inhibited by different drugs suggesting the protein as a new target for future antiviral chemotherapy. In the present review, we focused to bring together the recent development to explore the potential role of p7 protein in HCV infection and its inhibition as a therapy.     

New treatments for hepatitis C: Life cycle lessons

Despite progressive advances, therapy with interferon and ribavirin has been the mainstay of treatment for chronic hepatitis C for over a decade. With the development of in vitro systems to study viral replication, there have been great advances in the understanding of hepatitis C biology, and these advances, in turn, are allowing the development of specifically targeted antiviral therapies. This review employs our current understanding of the hepatitis C replicative life cycle as a framework on which to discuss new antiviral agents under clinical investigation.     

HIV and hepatitis C coinfection within the CAESAR study

The declining incidence of AIDS-related opportunistic diseases among people with HIV infection has shifted the focus of clinical management to prevention and treatment of comorbidities such as chronic liver disease. The increased risk of hepatitis C virus (HCV)-related advanced liver disease in people with HIV infection makes early HCV diagnosis a priority. To assess HCV prevalence and predictors of HIV/HCV coinfection, we have conducted a retrospective analysis of people enrolled in the CAESAR (Canada, Australia, Europe, South Africa) study, a multinational randomized placebo-controlled study of the addition of lamivudine to background antiretroviral therapy. The impact of HCV on HIV disease progression was also examined. Anti-HCV antibody testing on 1649 CAESAR study participants demonstrated a HIV/HCV coinfection prevalence of 16.1%, which varied from 1.9% in South Africa to 48.6% in Italy. The strongest predictor of HIV/HCV coinfection was HIV exposure category (P<0.0001), with odds ratios (ORs) compared to homosexual as follows: injecting drug use (IDU), 365 [95% confidence interval (CI): 179-742]; transfusion or blood products, 32.2 (95% CI: 15.2-67.6); homosexual and IDU, 22.9 (95% CI: 8.5-62.1). The prevalence of HIV/HCV was low (3.7%) among homosexual men without reported IDU. Other predictors of HIV/HCV coinfection were alanine aminotransferase (ALT), country of residence, ethnicity and stage of HIV disease. A history of IDU or ALT > or =40 U/L at baseline had a positive predictive value (PPV) of 35%, negative predictive value (NPV) of 96%, sensitivity of 82% and specificity of 71% for HIV/HCV coinfection. HIV disease progression was similar in HIV monoinfected and HIV/HCV coinfected patients. People with HIV and a history of IDU or elevated liver function tests should be targeted for HCV testing. The low prevalence of HIV/HCV coinfection among homosexual men without a history of IDU suggests low efficiency of sexual HCV transmission.