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Presents a letter to the editor about an article by I. Castillo, et al, on seronegative hepatitis C virus infection in individuals with persistently negative results of HCV-antibody tests.

Background. Tetrapyrrole substrates and products of heme oxygenase are potent inhibitors of hepatitis C virus (HCV) replication. It is not clear whether this occurs through primary induction of type I interferon (IFN), inhibition of viral NS3/4A protease, or a combination of these mechanisms. We studied the antiviral actions of tetrapyrroles and their potential influence on type I IFN induction.Methods. The effects of tetrapyrrole on NS3/4A protease activity and type I IFN induction were assessed in HCV-permissive cells, replicons, or human embryonic kidney (HEK) 293 cells transfected with NS3/4A protease. Activation of innate immune signaling was determined after transfection of double-strand surrogate nucleic acid antigens or infection with defined sequence HCV cell culture (HCVcc) RNA.Results. Tetrapyrroles failed to directly induce IFN expression at concentrations that inhibited HCV replication and NS3/4A protease activity. However, they potently restored IFN induction after attenuation with NS3/4A protease, a process accompanied by preservation of the adapter protein, mitochondrial antiviral signaling protein, nuclear localization of IFN regulatory factor 3, and augmentation of IFN-stimulated gene products.Conclusions. Tetrapyrroles do not directly induce IFN, but they dramatically restore type I IFN signaling pathway after attenuation with NS3/4A protease. They show immunomodulatory as well as antiprotease activity and may be useful for treatment of HCV infection. [ABSTRACT FROM AUTHOR]

Zinc protoporphyrin (ZnPP), a naturally occurring metalloprotoporphyrin (MPP), is currently under development as a chemotherapeutic agent although its mechanism is unclear. When tested against other MPPs, ZnPP was the most effective DNA synthesis and cellular proliferation inhibitor while promoting apoptosis in telomerase positive but not telomerase negative cells. Concurrently, ZnPP down-regulated telomerase expression and was the best overall inhibitor of telomerase activity in intact cells and cellular extracts with IC50 and EC50 values of ca 2.5 and 6 µM, respectively. The natural fluorescence properties of ZnPP enabled direct imaging in cellular fractions using non-denaturing agarose gel electrophoresis, western blots, and confocal fluorescence microscopy. ZnPP localized to large cellular complexes (>600 kD) that contained telomerase and dysskerin as confirmed with immunocomplex mobility shift, immunoprecipitation, and immunoblot analyses. Confocal fluorescence studies showed that ZnPP co-localized with telomerase reverse transcriptase (TERT) and telomeres in the nucleus of synchronized S-phase cells. Zn PP also co-localized with TERT in the perinuclear regions of log phase cells but did not co-localize with telomeres on the ends of metaphase chromosomes, a site known to be devoid of telomerase complexes. Overall, these results suggest that ZnPP does not bind to telomeric sequences per se, but alternatively, interacts with other structural components of the telomerase complex to inhibit telomerase activity. In conclusion, ZnPP actively interferes with telomerase activity in neoplastic cells, thus promoting pro-apoptotic and anti-proliferative properties. These data support further development of natural or synthetic protoporphyrins for use as chemotherapeutic agents to augment current treatment protocols for neoplastic disease. [ABSTRACT FROM AUTHOR]

Among human RNA viruses, hepatitis C virus (HCV) is unusual in that it causes persistent infection in the majority of infected people. To establish persistence, HCV evades host innate and adaptive immune responses by multiple mechanisms. Recent studies identified virus genome-derived small RNAs (vsRNAs) in HCV-infected cells; however, their biological significance during human HCV infection is unknown. One such vsRNA arising from the hepatitis C virus (HCV) E2 coding region impairs T cell receptor (TCR) signaling by reducing expression of a Src-kinase regulatory phosphatase (PTPRE) in vitro. Since TCR signaling is a critical first step in T cell activation, differentiation, and effector function, its inhibition may contribute towards HCV persistence in vivo. The effect of HCV infection on PTPRE expression in vivo has not been examined. Here, we found that PTPRE levels were significantly reduced in liver tissue and peripheral blood mononuclear cells (PBMCs) obtained from HCV-infected humans compared to uninfected controls. Loss of PTPRE expression impaired antigen-specific TCR signaling, and curative HCV therapy restored PTPRE expression in PBMCs; restoring antigen-specific TCR signaling defects. The extent of PTPRE expression correlated with the amount of sequence complementarity between the HCV E2 vsRNA and the PTPRE 3’ UTR target sites. Transfection of a hepatocyte cell line with full-length HCV RNA or with synthetic HCV vsRNA duplexes inhibited PTPRE expression, recapitulating the in vivo observation. Together, these data demonstrate that HCV infection reduces PTPRE expression in the liver and PBMCs of infected humans, and suggest that the HCV E2 vsRNA is a novel viral factor that may contribute towards viral persistence. [ABSTRACT FROM AUTHOR]

Introduction: Telomerase repairs the telomeric ends of chromosomes and is active in nearly all malignant cells. Hepatitis C virus (HCV) is known to be oncogenic and potential interactions with the telomerase system require further study. We determined the effects of HCV infection on human telomerase reverse transcriptase (TERT) expression and enzyme activity in primary human hepatocytes and continuous cell lines. Results: Primary human hepatocytes and Huh-7.5 hepatoma cells showed early de novo TERT protein expression 2–4 days after infection and these events coincided with increased TERT promoter activation, TERT mRNA, and telomerase activity. Immunoprecipitation studies demonstrated that NS3-4A protease-helicase, in contrast to core or NS5A, specifically bound to the C-terminal region of TERT through interactions between helicase domain 2 and protease sequences. Increased telomerase activity was noted when NS3-4A was transfected into cells, when added to reconstituted mixtures of TERT and telomerase RNA, and when incubated with high molecular weight telomerase ‘holoenzyme’ complexes. The NS3-4A catalytic effect on telomerase was inhibited with primuline or danoprevir, agents that are known to inhibit NS3 helicase and protease activities respectively. In HCV infected cells, NS3-4A could be specifically recovered with telomerase holoenzyme complexes in contrast to NS5A or core protein. HCV infection also activated the effector caspase 7 which is known to target TERT. Activation coincided with the appearance of lower molecular weight carboxy-terminal fragment(s) of TERT, chiefly sized at 45 kD, which could be inhibited with pancaspase or caspase 7 inhibitors. Conclusions: HCV infection induces TERT expression and stimulates telomerase activity in addition to triggering Caspase activity that leads to increased TERT degradation. These activities suggest multiple points whereby the virus can influence neoplasia. The NS3-4A protease-helicase can directly bind to TERT, increase telomerase activity, and thus potentially influence telomere repair and host cell neoplastic behavior. [ABSTRACT FROM AUTHOR]

Background: As the era of interferon-alpha (IFN)-based therapy for hepatitis C ends, long-term treatment outcomes are now being evaluated.Aim: To more fully understand the natural history of hepatitis C infection by following a multisite cohort of patients.Methods: Patients with chronic HCV were prospectively enrolled in 1999-2000 from 11 VA medical centers and followed through retrospective medical record review.Results: A total of 2211 patients were followed for an average of 8.5 years after enrollment. Thirty-one percent of patients received HCV antiviral therapy, 15 % with standard IFN/ribavirin only, 16 % with pegylated IFN/ribavirin, and 26.7 % of treated patients achieved sustained virologic response (SVR). Cirrhosis developed in 25.8 % of patients. Treatment nonresponders had a greater than twofold increase in the hazard of cirrhosis and hepatocellular carcinoma, compared to untreated patients, whereas SVR patients were only marginally protected from cirrhosis. Nearly 6 % developed hepatocellular carcinoma, and 27.1 % died during the follow-up period. Treated patients, regardless of response, had a significant survival benefit compared to untreated patients (HR 0.58, CI 0.46-0.72). Improved survival was also associated with college education, younger age, lower levels of alcohol consumption, and longer duration of medical service follow-up-factors typically associated with treatment eligibility.Conclusions: As more hepatitis C patients are now being assessed for all-oral combination therapy, these results highlight that patient compliance and limiting harmful behaviors contribute a significant proportion of the survival benefit in treated patients and that the long-term clinical benefits of SVR may be less profound than previously reported. [ABSTRACT FROM AUTHOR]

Background: Chronic hepatitis C virus (HCV)-induced liver fibrosis involves upregulation of transforming growth factor (TGF)-β and subsequent hepatic stellate cell (HSC) activation. MicroRNAs (miRNAs) regulate HCV infection and HSC activation.Methods: TaqMan miRNA profiling identified 12 miRNA families differentially expressed between chronically HCV-infected human livers and uninfected controls. To identify pathways affected by miRNAs, we developed a new algorithm (pathway analysis of conserved targets), based on the probability of conserved targeting.Results: This analysis suggested a role for miR-29 during HCV infection. Of interest, miR-29 was downregulated in most HCV-infected patients. miR-29 regulates expression of extracellular matrix proteins. In culture, HCV infection downregulated miR-29, and miR-29 overexpression reduced HCV RNA abundance. miR-29 also appears to play a role in HSCs. Hepatocytes and HSCs contribute similar amounts of miR-29 to whole liver. Both activation of primary HSCs and TGF-β treatment of immortalized HSCs downregulated miR-29. miR-29 overexpression in LX-2 cells decreased collagen expression and modestly decreased proliferation. miR-29 downregulation by HCV may derepress extracellular matrix synthesis during HSC activation.Conclusions: HCV infection downregulates miR-29 in hepatocytes and may potentiate collagen synthesis by reducing miR-29 levels in activated HSCs. Treatment with miR-29 mimics in vivo might inhibit HCV while reducing fibrosis. [ABSTRACT FROM AUTHOR]

Background and Aims: Increased levels of nitric oxide (NO) are hypothesized to contribute to renal dysfunction in patients with decompensated cirrhosis. In this study, we examined whether splanchnic and/or peripheral NO levels and L-arginine (L-Arg) correlate with progressive renal dysfunction in cirrhotics. Methods: Serum NO metabolites (NOx) and L-Arg were measured in: controls ( n = 10); organ donors ( n = 12); compensated cirrhotics ( n = 17), cirrhotics with ascites ( n = 25), refractory ascites ( n = 11) or hepatorenal syndrome type II (HRS) ( n = 11) and chronic renal failure patients ( n = 18). Results: Plasma NOx and L-Arg levels rose progressively with worsening renal function in decompensated cirrhotics. Both NOx and L-Arg levels were highest in patients with HRS ( P < 0.001 and P < 0.025, respectively). While there were no differences in NOx levels related to the site of sampling, L-Arg levels were lowest in hepatic venous blood. There were significant relationships of NOx and L-Arg with Model for End-Stage Liver Disease score and Child–Pugh scores ( P < 0.04 and P < 0.01, respectively). Multivariate analysis showed a significant relationship between NOx, L-Arg and HRS. Conclusion: Worsening renal function in decompensated cirrhosis is accompanied by progressive elevation in plasma NOx and L-Arg. These findings support the hypothesis that NO-mediated vasodilation is probably linked with the mechanism of progressive renal failure in decompensated cirrhotics. [ABSTRACT FROM AUTHOR]

Abstract: Telomeres are repeated sequences at chromosome ends that are incompletely replicated during mitosis. Telomere shortening caused by proliferation or oxidative damage culminates in replicative arrest and senescence, which may impair regeneration during chronic liver injury. Whereas the effects of experimental liver injury on telomeres have received little attention, prior studies suggest that telomerase, the enzyme complex that catalyzes the addition of telomeric repeats, is protective in some rodent liver injury models. Thus, the aim of this study was to determine the effects of iron overload on telomere length and telomerase activity in rat liver. Mean telomere lengths were similar in iron−loaded and control livers. However, telomerase activity was increased 3-fold by iron loading, with no change in levels of TERT mRNA or protein. Because thiol redox state has been shown to modulate telomerase activity in vitro, hepatic thiols were assessed. Significant increases in GSH (1.5-fold), cysteine (15-fold), and glutamate cysteine ligase activity (1.5-fold) were observed in iron-loaded livers, whereas telomerase activity was inhibited by treatment with N-ethylmaleimide. This is the first demonstration of increased telomerase activity associated with thiol alterations in vivo. Enhanced telomerase activity may be an important factor contributing to the resistance of rodent liver to iron-induced damage. [Copyright &y& Elsevier]

BACKGROUND: Many veterans may not be candidates for hepatitis C virus (HCV) treatment due to contraindications to therapy. The aims of this study were to determine the proportion of HCV-infected veterans who were eligible for interferon alfa and ribavirin therapy and to evaluate barriers to HCV treatment. METHODS: We prospectively enrolled 4,084 veterans who were referred for HCV treatment over a 1-yr period at 24 Veterans Affairs (VA) Medical Centers. Treatment candidacy was assessed using standardized criteria and the opinion of the treating clinician. RESULTS: Overall, 32.2% (95% CI, 30.8–33.7%) were candidates for HCV treatment according to standardized criteria, whereas 40.7% (95% CI, 39.2–42.3%) were candidates in the opinion of the treating clinician. Multivariable analysis identified ongoing substance abuse (OR = 17.68; 95% CI, 12.24–25.53), comorbid medical disease (OR = 9.62; 95% CI, 6.85–13.50), psychiatric disease (OR = 9.45; 95% CI, 6.70–13.32), and advanced liver disease (OR = 8.43; 95% CI, 4.42–16.06) as the strongest predictors of not being a treatment candidate. Among patients who were considered treatment candidates, 76.2% (95% CI, 74.0–78.3%) agreed to be treated and multivariable analysis showed that persons ≥50 yr of age (OR = 1.37; 95% CI, 1.07–1.76) and those with >50 lifetime sexual partners (OR = 1.44; 95% CI, 1.08–1.93) were more likely to decline treatment. CONCLUSIONS: The majority of veteran patients are not suitable candidates for HCV treatment because of substance abuse, psychiatric disease, and comorbid medical disease, and many who are candidates decline therapy. Multidisciplinary collaboration is needed to overcome barriers to HCV therapy in this population. (Am J Gastroenterol 2005;100:1–8) [ABSTRACT FROM AUTHOR]

Kayali Z, Ranguelov R, Mitros F, Shufelt C, Elmi F, Rayhill SC, Schmidt WN, Brown KE. Hemosiderosis is associated with accelerated decompensation and decreased survival in patients with cirrhosis.Liver International 2005: 25: 41–48.© Blackwell Munksgaard 2005Although hepatic iron deposition unrelated to hereditary hemochromatosis is commonly observed in cirrhosis, its clinical significance is unclear. The aim of this study was to examine the outcomes of cirrhotic patients with and without hemosiderosis.Patients with an initial liver biopsy demonstrating cirrhosis between January 1993 and December 1997 were identified using the Department of Pathology database. Based on iron staining, patients were characterized as siderotic or nonsiderotic. Charts were reviewed to determine outcomes.Siderotic patients had significantly higher Child–Pugh (CP) and model for end-stage liver disease (MELD) scores. Their median survival without transplant was 23 months vs. 85 months in the nonsiderotics (P<0.0001, confidence interval: 95%). On univariate analysis, siderosis was associated with a hazard ratio of 2.74 (P<0.0001). On multivariate analysis, the effect of siderosis was reduced but remained significant after correction for the CP or MELD score (hazard ratios 1.82 and 2.06,P=0.05 and 0.02, respectively). Child's A cirrhotics with hemosiderosis decompensated more rapidly and had shorter median survival than those without siderosis (P=0.007 andP=0.01, respectively).The presence of siderosis is associated with more advanced liver dysfunction. Even when the effects of baseline liver function are taken into account, siderosis is associated with decreased survival and more rapid decompensation in cirrhosis. [ABSTRACT FROM AUTHOR]

Antioxidant enzymes, including heme oxygenase (HO)-1, are an important line of defense against oxidant-mediated liver injury. Because hepatitis C virus (HCV) infection appears to increase the production of oxidants, we evaluated levels of antioxidant enzymes and HO-1 in liver-biopsy samples from HCV-infected patients by immunoblot and semiquantitative reverse-transcriptase polymerase chain reaction. In HCV-infected liver samples, levels of immunoreactive HO-1 and HO-1 mRNA were >4-fold lower than levels in control samples, but levels of superoxide dismutase and catalase were unaffected. Immunohistochemical results confirmed the decreased expression of HO-1 in hepatocytes from liver samples from HCV-infected patients but not in those from patients with other chronic liver diseases. The expression of HO-1 was also reduced in cell lines that stably express HCV core protein, which suggests that core gene products are capable of regulating the expression of HO-1. [ABSTRACT FROM AUTHOR]

Examines the presence of hepatitic C virus viremia in persons without detectable HCV antibodies. Characterization of serosilent HCV infection; Characteristics of persons acquiring HIV through transfusion of blood products; Percentage of HIV-positive intravenous drug users affected with HCV infection.