Molecular mechanisms of hepatitis C virus, potential therapeutic targets [Mecanismos moleculares del virus de la hepatitis C, potenciales blancos terapéuticos]

Hepatitis C Virus (HCV) is an emerging virus of great medical significance, because infection with this virus, which is essentially transmitted by blood, is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. HCV is an enveloped plus-strand RNA virus that belongs to the Flaviviridae family. The first cloning of the HCV genome, about 13 years ago, initiated research efforts leading to the elucidation of genomic organization and definition of the functions of the most viral proteins. While current therapeutic options for hepatitis C are limited, recent progress in the understanding of the HCV molecular virology (genomic sequence, viral replication mechanisms, translational control mechanisms and tridimensional structure of viral proteins) led to the identification of potential new viral targets for antiviral strategies. Based upon these current knowledge, molecular and immunotherapeutic strategies to inhibit HCV replication or viral gene expression are being explored. This review focuses on the viral structure organization, protein functions and novel antiviral therapy approaches along with their biological and clinical significance

Role of probiotics in hepatic ischemia-reperfusion injury

[No abstract available

Hepatic artery reconstruction with inferior mesenteric vein graft in pediatric living donor liver transplantation

In Latin America few studies have explored frequency and risk factors predicting hepatitis C virus (HCV) infection in blood donors. In this study we determined the prevalence of HCV infection in blood donors from West Mexico. Potential risk factors, clinical, histological and virologic characteristics presented in this group were also evaluated. Methods: HCV antibodies were evaluated in 57 108 blood donors with commercial second-generation enzyme immunoassays. Positive results were confirmed by a recombinant immunoblot assay. Repeatedly seropositive donors were further studied for risk factors, history for hepatitis, hepatic enzymes (aspartate aminotransferase and alanine aminotransferase (AST and ALT)), liver histology and hepatitis C virus-ribonucleic acid (HCV-RNA) detection. Results: A total of 499 blood donors were initially tested positive doubtful for antibodies to HCV Ab (0.8%). While there was no difference in HCV prevalence with respect to age or gender, the most frequent risk factors identified were transfusion (42%), household exposure (14.8%), multiple sex partner (6.8%) and intranasal cocaine use (2.3%). Also, we found that from a subgroup of donors tested for histological analysis, 19% presented abnormal ALT levels and 90% showed abnormal liver histology. No correlation was found between abnormal ALT levels and the presence of HCV-RNA in serum. Conclusion: These results demonstrate a low prevalence (0.8%) of HCV infection among Western Mexican blood donors, which was comparable to those established for Western countries, but in contrast in our study the most frequent risk factor continues being transfusion followed by household exposure. " 2002 Elsevier Science B.V. All rights reserved.",,,,,,"10.1016/S1386-6346(02)00243-7",,,"http://hdl.handle.net/20.500.12104/41875","WOS",,,,,,"2",,"Hepatology Research",,"11

Hepatitis C virus: Prevalence and routes of infection among blood donors of West Mexico

In Latin America few studies have explored frequency and risk factors predicting hepatitis C virus (HCV) infection in blood donors. In this study we determined the prevalence of HCV infection in blood donors from West Mexico. Potential risk factors, clinical, histological and virologic characteristics presented in this group were also evaluated. Methods: HCV antibodies were evaluated in 57 108 blood donors with commercial second-generation enzyme immunoassays. Positive results were confirmed by a recombinant immunoblot assay. Repeatedly seropositive donors were further studied for risk factors, history for hepatitis, hepatic enzymes (aspartate aminotransferase and alanine aminotransferase (AST and ALT)), liver histology and hepatitis C virus-ribonucleic acid (HCV-RNA) detection. Results: A total of 499 blood donors were initially tested positive doubtful for antibodies to HCV Ab (0.8%). While there was no difference in HCV prevalence with respect to age or gender, the most frequent risk factors identified were transfusion (42%), household exposure (14.8%), multiple sex partner (6.8%) and intranasal cocaine use (2.3%). Also, we found that from a subgroup of donors tested for histological analysis, 19% presented abnormal ALT levels and 90% showed abnormal liver histology. No correlation was found between abnormal ALT levels and the presence of HCV-RNA in serum. Conclusion: These results demonstrate a low prevalence (0.8%) of HCV infection among Western Mexican blood donors, which was comparable to those established for Western countries, but in contrast in our study the most frequent risk factor continues being transfusion followed by household exposure. © 2002 Elsevier Science B.V. All rights reserved

Absolute quantitation of different genotypes of hepatitis C virus RNA in clinical samples by a modified real-time PCR method

Background: Our aim was to develop a quantitative real-time polymerase chain reaction (qPCR) assay for the quantitation of hepatitis C virus (HCV) RNA samples from patients infected with different HCV genotypes. Methods: A standard curve was generated by amplification of serial dilutions of HCV-plasmid (pFKI389-NS3-3') harboring genotype 1b HCV-subgenomic replicon. Samples from 15 HCV-infected patients (genotypes 1, 2, and 3) were analyzed to quantify HCV-RNA by qPCR with primers and probes specific for the 5'-UTR viral region. Results: The HCV qPCR assay had a sensitivity of 100 copies/reaction with a dynamic range of detection between 10 2-20 � 10 6 HCV copies. The assay was highly reproducible with a low coefficient of variation. We observed that the HCV genotypes included could be identified by our method. Conclusions: Our results showed that this modified qPCR assay provides a valid platform for quantifying HCV-RNA, combining good analytical sensitivity with a wide dynamic range and high reproducibility

Tumor necrosis factor ? down-regulates expression of the ?1(I) collagen gene in rat hepatic stellate cells through a p20C/EBP?- and C/EBP?-dependent mechanism

Tumor necrosis factor ? (TNF-?) is one of the key cytokines of the acute phase response and of many inflammatory processes. This cytokine has several antifibrogenic actions and down-regulates the expression of the type I collagen genes and induces the expression of metalloproteinases. Because TNF-? directly antagonizes some fibrogenic actions of transforming growth factor ?1 (TGF-?1), we considered it important to map the cis-acting regulatory element of the ?1(I) collagen (col1a1) promoter involved in TNF- ? responsiveness in hepatic stellate cells (HSC), to investigate the transcription factors that bind to it, and to establish possible mechanisms by which TNF-? downregulates its expression. In this article, we show the presence of a functional TNF-?-responsive element (TaRE) in the -378 to -345 region of the col1a1 promoter. This element colocalizes with a previously reported TGF-?1-responsive element. We further demonstrate that TNF-? induces nuclear translocation and binding of transcriptional complexes containing p20C/EBP?, p35C/EBP?, and C/EBP? to this sequence of the promoter. Transient overexpression of C/EBP? or p20C/EBP?, the natural dominant negative form of C/EBP? in HSC, down-regulated activity of a CAT reporter vector driven by -412 to +110 of the col1a1 promoter. Taken together, these data suggest that the -378 to -340 region of the col1a1 promoter is the site of convergence of different stimuli that ultimately modulate col1a1 gene transcription

Tumor necrosis factor α down-regulates expression of the α1(I) collagen gene in rat hepatic stellate cells through a p20C/EBPβ- and C/EBPδ-dependent mechanism

Tumor necrosis factor α (TNF-α) is one of the key cytokines of the acute phase response and of many inflammatory processes. This cytokine has several antifibrogenic actions and down-regulates the expression of the type I collagen genes and induces the expression of metalloproteinases. Because TNF-α directly antagonizes some fibrogenic actions of transforming growth factor β1 (TGF-β1), we considered it important to map the cis-acting regulatory element of the α1(I) collagen (col1a1) promoter involved in TNF- α responsiveness in hepatic stellate cells (HSC), to investigate the transcription factors that bind to it, and to establish possible mechanisms by which TNF-α downregulates its expression. In this article, we show the presence of a functional TNF-α-responsive element (TaRE) in the -378 to -345 region of the col1a1 promoter. This element colocalizes with a previously reported TGF-β1-responsive element. We further demonstrate that TNF-α induces nuclear translocation and binding of transcriptional complexes containing p20C/EBPβ, p35C/EBPβ, and C/EBPδ to this sequence of the promoter. Transient overexpression of C/EBPδ or p20C/EBPβ, the natural dominant negative form of C/EBPβ in HSC, down-regulated activity of a CAT reporter vector driven by -412 to +110 of the col1a1 promoter. Taken together, these data suggest that the -378 to -340 region of the col1a1 promoter is the site of convergence of different stimuli that ultimately modulate col1a1 gene transcription

Acetylsalicylic acid inhibits hepatitis C virus RNA and protein expression through cyclooxygenase 2 signaling pathways

It has been reported that salicylates (sodium salicylate and aspirin) inhibit the replication of flaviviruses, such as Japanese encephalitis virus and dengue virus. Therefore, we considered it important to test whether acetylsalicylic acid (ASA) had anti-hepatitis C virus (HCV) activity. To this end, we examined the effects of ASA on viral replication and protein expression, using an HCV subgenomic replicon cell culture system. We incubated Huh7 replicon cells with 2-8 mM ASA for different times and measured HCV-RNA and protein levels by northern blot, real-time polymerase chain reaction, and western analysis, respectively. We found that ASA had a suppressive effect on HCV-RNA and protein levels (nearly 58%). ASA-dependent inhibition of HCV expression was not mediated by the 5′-internal ribosome entry site or 3′-untranslated regions, as determined by transfection assays using bicistronic constructs containing these regulatory regions. However, we found that HCV-induced cyclooxygenase 2 (COX-2) messenger RNA and protein levels and activity and these effects were down-regulated by ASA, possibly by a nuclear factor kappa B-independent mechanism. We also observed that the ASA-dependent inhibition of viral replication was due in part to inhibition of COX-2 and activation of p38 and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 (MEK1/2) mitogen-activated protein kinases (MAPKs). Inhibition of these kinases by SB203580 and U0126, respectively, and by short interfering RNA silencing of p38 and MEK1 MAPK prevented the antiviral effect of ASA. Taken together, our findings suggest that the anti-HCV effect of ASA in the Huh7 replicon cells is due to its inhibitory effect on COX-2 expression, which is mediated in part by the activation of MEK1/2/p38 MAPK. Conclusion: These findings suggest the possibility that ASA could be an excellent adjuvant in the treatment of chronic HCV infection. Copyright © 2008 by the American Association for the Study of Liver Diseases