A large-scale genetic validation study coupled with in vitro analyses reveal a role for vitamin Dsignaling in the pathogenesis and response to treatment of hepatitis C virus infection

Background and Aims: Vitamin D is an important modulatorof numerous cellular processes. Some of us recently observedan association of the 1a-hydroxylase promoter polymorphismCYP27B1-1260 rs10877012 with sustained virologic response (SVR)in a relatively small number of German patients with chronichepatitis C. In the present study, we aimed to validate thisassociation in a large and well characterized patient cohort, theSwiss Hepatitis C Cohort Study (SCCS). In addition, we examinedthe effect of vitamin D on the hepatitis C virus (HCV) life cyclein vitro.Methods: CYP27B1-1260 rs10877012 and IL28B rs12979860 singlenucleotide polymorphisms (SNPs) were genotyped in 1049 patientswith chronic hepatitis C from the SCCS, of whom 698 were treatedwith pegylated interferon-a (PEG-IFN-a) and ribavirin. In addition,112 patients with spontaneous clearance of HCV were examined.SNPs were correlated with variables reflecting the natural courseand treatment outcome of chronic hepatitis C. The effect of1,25-(OH)2D3 (calcitriol) on HCV replication and viral particleproduction was investigated in vitro using human hepatoma celllines (Huh-7.5) harbouring subgenomic replicons and cell culturederivedHCV.Results: The CYP27B1-1260 rs10877012 genotype was notassociated with SVR in patients with the good-response IL28Brs1279860 CC genotype. However, in patients with poor-responseIL28B rs1279860 genotype CT and TT, CYP27B1-1260 rs10877012was a significant independent predictor of SVR (15% difference inSVR between rs10877012 genotype AA vs. CC, p = 0.030, OR = 1.495,95% CI = 1.038-2.152). The CYPB27-1260 rs10877012 genotype wasneither associated with spontaneous clearance of HCV, nor withliver fibrosis progression rate, inflammatory activity of chronichepatitis C, or HCV viral load. Physiological doses of 1,25-(OH)2D3did not significantly affect HCVRNA replication or infectiousparticle production in vitro.Conclusions: The results of this large-scale genetic validationstudy reveal a role of vitamin D metabolism in the responseto treatment in chronic hepatitis C, but 1,25-(OH)2D3 does notexhibit a significant direct inhibitory antiviral effect. Thus, theability of vitamin D to modulate immunity against HCV shouldbe investigated.

The cyclophilin inhibitor alisporivir prevents hepatitis C virus-mediated mitochondrial dysfunction.

Alisporivir (Debio-025) is an analogue of cyclosporine A and represents the prototype of a new class of non-immunosuppressive cyclophilin inhibitors. In vitro and in vivo studies have shown that alisporivir inhibits hepatitis C virus (HCV) replication, and ongoing clinical trials are exploring its therapeutic potential in patients with chronic hepatitis C. Recent data suggest that the antiviral effect is mediated by inhibition of cyclophilin A, which is an essential host factor in the HCV life cycle. However, alisporivir also inhibits mitochondrial permeability transition by binding to cyclophilin D. Because HCV is known to affect mitochondrial function, we explored the effect of alisporivir on HCV protein-mediated mitochondrial dysfunction. Through the use of inducible cell lines, which allow to investigate the effects of HCV polyprotein expression independent from viral RNA replication and which recapitulate the major alterations of mitochondrial bioenergetics observed in infectious cell systems, we show that alisporivir prevents HCV protein-mediated decrease of cell respiration, collapse of mitochondrial membrane potential, overproduction of reactive oxygen species and mitochondrial calcium overload. Strikingly, some of the HCV-mediated mitochondrial dysfunctions could even be rescued by alisporivir. Conclusion: These observations provide new insights into the pathogenesis of HCV-related liver disease and reveal an additional mechanism of action of alisporivir that is likely beneficial in the treatment of chronic hepatitis C. (HEPATOLOGY 2012).

Role of hepatitis C virus genotype 3 in liver fibrosis progression: a systematic review and meta-analysis.

The progression of liver fibrosis in chronic hepatitis C has long been considered to be independent from viral genotypes. However, recent studies suggest an association between Hepatitis C virus (HCV) genotype 3 and accelerated liver disease progression. We completed a systematic review and meta-analysis of studies evaluating the association between HCV genotypes and fibrosis progression. PubMed, Embase and ISI Web of Knowledge databases were searched for cohort, cross-sectional and case-control studies on treatment-naïve HCV-infected adults in which liver fibrosis progression rate (FPR) was assessed by the ratio of fibrosis stage in one single biopsy to the duration of infection (single-biopsy studies) or from the change in fibrosis stage between two biopsies (paired biopsies studies). A random effect model was used to derive FPR among different HCV genotypes. Eight single-biopsy studies (3182 patients, mean/median duration of infection ranging from 9 to 21 years) and eight paired biopsies studies (mean interval between biopsies 2-12 years) met the selection criteria. The odds ratio for the association of genotype 3 with accelerated fibrosis progression was 1.52 (95% CI 1.12-2.07, P = 0.007) in single-biopsy studies and 1.37 (95% CI 0.87-2.17, P = 0.17) in paired biopsy studies. In conclusion, viral genotype 3 was associated with faster fibrosis progression in single-biopsy studies. This observation may have important consequences on the clinical management of genotype 3-infected patients. The association was not significant in paired biopsies studies, although the latter may be limited by important indication bias, short observation time and small sample size.

Identification of GPx8 as a novel cellular substrate of the hepatitis C virus NS3-4A protease

Background: The hepatitis C virus (HCV) NS3-4A protease is not only an essential component of the viral replication complex and a prime target for a ntiviral intervention but also a key player i n the persistence and pathogenesis of HCV. It cleaves and thereby inactivates two crucial adaptor proteins in viral RNA sensing and innate immunity (MAVS and TRIF) as well as a phosphatase involved in growth factor signaling (TCPTP). T he aim of this study was to identify novel cellular substrates o f the N S3-4A protease and to investigate their role in the replication and pathogenesis of HCV. Methods: Cell lines inducibly expressing t he NS3-4A protease were analyzed in basal as well as interferon-α-stimulated states by stable isotopic l abeling using amino acids in cell culture (SILAC) coupled with protein separation and mass spectrometry. Candidates fulfilling stringent criteria for potential substrates or products of the NS3-4A protease were further i nvestigated in different experimental systems as well a s in liver biopsies from patients with chronic hepatitis C. Results: SILAC coupled with protein separation and mass spectrometry yielded > 5000 proteins of which 18 candidates were selected for further analyses. These allowed us to identify GPx8, a membrane-associated peroxidase involved in disulfide bond formation in the endoplasmic reticulum, as a n ovel cellular substrate of the H CV NS3-4A protease. Cleavage occurs at cysteine in position 11, removing the cytosolic tip of GPx8, and was observed in different experimental systems as well as in liver biopsies from patients with chronic hepatitis C. Further functional studies, involving overexpression and RNA silencing, revealed that GPx8 is a p roviral factor involved in viral particle production but not in HCV entry or HCV RNA replication. Conclusions: GPx8 is a proviral host factor cleaved by the HCV NS3-4A protease. Studies investigating the consequences of GPx8 cleavage for protein function are underway. The identification of novel cellular substrates o f the HCV N S3-4A protease should yield new insights i nto the HCV life cycle and the pathogenesis of hepatitis C and may reveal novel targets for antiviral intervention.

Viral genotype-specific role of PNPLA3, PPARG, MTTP, and IL28B in hepatitis C virus-associated steatosis.

BACKGROUND & AIMS: Steatosis is a prominent feature of hepatitis C, especially in patients infected with genotype 3. The analysis of genetic polymorphisms influencing steatosis in chronic hepatitis C has been limited by the studies' small sample size, and important single nucleotide polymorphisms (SNPs), such as those in the patatin-like phospholipase family 3 protein (PNPLA3), were never evaluated. METHODS: We analyzed the role of SNPs, from 19 systematically selected candidate genes, on steatosis in 626 Caucasian hepatitis C virus (HCV) infected patients. SNPs were extracted from a genome-wide association-generated dataset. Associations of alleles with the presence and/or different severity of steatosis were evaluated by univariate and multivariate logistic regression, accounting for all relevant covariates. RESULTS: The risk of steatosis was increased by carriage of I148M in PNPLA3, but only in patients with HCV genotypes non-3 (odds ratio [OR]=1.9, 95% confidence interval [CI]=1.6-2.3, p<0.001) and similar, albeit weaker associations were found for SNPs in peroxisome proliferator-activated receptor-γ (PPARG) and interleukin-28B (IL28B). Carriage of a SNP in the microsomal triglyceride transfer protein (MTTP) increased the risk of steatosis, but only in patients with HCV genotype 3 (rs1800803, OR=3.4, 95% CI=2.4-4.9, p=0.001). CONCLUSIONS: The rs738409 SNP in PNPLA3 is associated with an increased risk of steatosis in patients infected with HCV genotypes non-3. Host genes affect steatosis depending on the infecting HCV genotype, suggesting their interaction with viral factors.

Impact of donor and recipient IL28B rs12979860 genotypes on hepatitis C virus liver graft reinfection.

BACKGROUND & AIMS: Recent studies have described a major impact of genetic variations near the IL28B gene on the natural course and outcome of antiviral therapy in chronic hepatitis C. We therefore, aimed to explore the impact of donor and recipient genotypes of these polymorphisms on hepatitis C virus (HCV) liver graft reinfection. METHODS: Donor and recipient genotypes of IL28B rs12979860C>T single nucleotide polymorphism were determined in 91 patients with HCV liver graft reinfection, 47 of whom were treated with pegylated interferon-α (PEG-IFN-α) and ribavirin. IL28B genetic polymorphisms were correlated with the natural course and treatment outcome of recurrent hepatitis C. RESULTS: Patients requiring liver transplantation due to end-stage chronic hepatitis C appeared to be selected toward the adverse genotypes rs12979860 CT/TT compared to non-transplanted HCV-infected patients (p=0.046). Patients with the donor genotype rs12979860 CC had higher peak ALT and HCV RNA serum concentrations than those with CT/TT (p=0.04 and 0.06, respectively). No association was observed between ALT/HCV RNA serum concentrations and recipient genotypes (p>0.3). More important, donor IL28B rs12979860 CC vs. CT/TT genotypes were associated with rapid, complete early, and sustained virologic response (RVR, cEVR, SVR) to treatment with PEG-IFN-α and ribavirin (p=0.003, 0.0012, 0.008, respectively), but weaker associations of recipient genotypes with RVR, cEVR, and SVR were observed as well (p=0.0046, 0.115, 0.118, respectively). CONCLUSIONS: We provide evidence for a dominant, but not exclusive impact of the donor rather than the recipient IL28B genetic background on the natural course and treatment outcome of HCV liver graft reinfection.

Genetic association analyses reveal a role for vitamin D insufficiency in hepatitis C virus-associated hepatocellular carcinoma development

Background: V itamin D insufficiency has been associated with the occurrence of various types of cancer, but causal relationships remain elusive. Methods: Associations between t he r isk o f HCV-related HCC development and CYP2R1 , GC, and DHCR7 genotypes, which are genetic determinants of reduced 25-OH-vitamin D3 (25[OH]D3) serum levels, were determined. Results: A t otal of 5604 HCV-infected patients, 1279 with a nd 4325 without progression to HCC, w ere identified. The well-known association between 25(OH)D3 s erum levels and variations in CYP2R1 ( rs1993116, rs10741657), GC ( rs2282679), a nd DHCR7 ( rs7944926, rs12785878) g enotypes was also apparent in patients w ith chronic hepatitis C. The same genotypes of t hese single nucleotide polymorphisms (SNPs), w hich are associated with reduced 25(OH)D3 s erum levels, were significantly associated with HCV-associated HCC (P=0.07 [OR=1.13] for CYP2R1 , P=0.007 [OR=1.56] for GC, P=0.003 [OR=1.42] for DHCR7; ORs for risk genotypes). In contrast, no association between t hese genetic variations and the o utcome of antiviral therapy with pegylated interferon-α and ribavirin ( P>0.2 for e ach SNP) or liver fibrosis progression rate (P>0.2 for each SNP) was observed, s uggesting a specific influence o f the genetic d eterminants of 25(OH)D3 s erum levels o n hepatocarcinogenesis. Conclusions: Our data suggest a relatively weak but functionally relevant role for vitamin D in the prevention of HCV-related HCC development. Controlled clinical trials to assess the benefit of vitamin D supplementation in HCVinfected patients with advanced liver fibrosis or cirrhosis are warranted.

Protease inhibitors to treat hepatitis C in the Swiss HIV Cohort Study: high efficacy but low treatment uptake.

OBJECTIVES: Direct-acting antiviral agents (DAAs) have become the standard of care for the treatment of chronic hepatitis C virus (HCV) infection. We aimed to assess treatment uptake and efficacy in routine clinical settings among HIV/HCV coinfected patients after the introduction of the first generation DAAs. METHODS: Data on all Swiss HIV Cohort Study (SHCS) participants starting HCV protease inhibitor (PI) treatment between September 2011 and August 2013 were collected prospectively. The uptake and efficacy of HCV therapy were compared with those in the time period before the availability of PIs. RESULTS: Upon approval of PI treatment in Switzerland in September 2011, 516 SHCS participants had chronic HCV genotype 1 infection. Of these, 57 (11%) started HCV treatment during the following 2 years with either telaprevir, faldaprevir or boceprevir. Twenty-seven (47%) patients were treatment-naïve, nine (16%) were patients with relapse and 21 (37%) were partial or null responders. Twenty-nine (57%) had advanced fibrosis and 15 (29%) had cirrhosis. End-of-treatment virological response was 84% in treatment-naïve patients, 88% in patients with relapse and 62% in previous nonresponders. Sustained virological response was 78%, 86% and 40% in treatment-naïve patients, patients with relapse and nonresponders, respectively. Treatment uptake was similar before (3.8 per 100 patient-years) and after (6.1 per 100 patient-years) the introduction of PIs, while treatment efficacy increased considerably after the introduction of PIs. CONCLUSIONS: The introduction of PI-based HCV treatment in HIV/HCV-coinfected patients improved virological response rates, while treatment uptake remained low. Therefore, the introduction of PIs into the clinical routine was beneficial at the individual level, but had only a modest effect on the burden of HCV infection at the population level.

Hépatite C: traitement actuel [Hepatitis C: current therapy].

Le traitement de l'hépatite C chronique a été révolutionné par l'introduction de nouveaux antiviraux (directly acting antivirals [DAA]). Ces inhibiteurs de protéase, de la protéine NS5A et de la polymérase peuvent être associés dans des traitements oraux hautement efficaces et bien tolérés sans interféron. Dans cet article, nous fournissons un aperçu du traitement actuel de l'hépatite C chronique avec considération particulière des DAA actuellement autorisés en Suisse. Treatment of chronic hepatitis C is currently being revolutionised, with the introduction of directly acting antivirals (DAA), including protease, NS5A and polymerase inhibitors. These can be combined in interferon-free oral therapies with unprecedented efficacy and good tolerance. Here, we review the current therapy of chronic hepatitis C, with a particular focus on DAA that are approved in Switzerland today.

Overlapping pathways to transplant glomerulopathy: chronic humoral rejection, hepatitis C infection, and thrombotic microangiopathy.

Transplant glomerulopathy (TG) has received much attention in recent years as a symptom of chronic humoral rejection; however, many cases lack C4d deposition and/or circulating donor-specific antibodies (DSAs). To determine the contribution of other causes, we studied 209 consecutive renal allograft indication biopsies for chronic allograft dysfunction, of which 25 met the pathological criteria of TG. Three partially overlapping etiologies accounted for 21 (84%) cases: C4d-positive (48%), hepatitis C-positive (36%), and thrombotic microangiopathy (TMA)-positive (32%) TG. The majority of patients with confirmed TMA were also hepatitis C positive, and the majority of hepatitis C-positive patients had TMA. DSAs were significantly associated with C4d-positive but not with hepatitis C-positive TG. The prevalence of hepatitis C was significantly higher in the TG group than in 29 control patients. Within the TG cohort, those who were hepatitis C-positive developed allograft failure significantly earlier than hepatitis C-negative patients. Thus, TG is not a specific diagnosis but a pattern of pathological injury involving three major overlapping pathways. It is important to distinguish these mechanisms, as they may have different prognostic and therapeutic implications.

Overlapping Pathways to Transplant Glomerulopathy: Chronic Humoral Rejection, Hepatitis C Infection and Thrombotic Microangiopathy

Background:Transplant glomerulopathy (TG) has received much attention in recent years as a manifestation of chronic humoral rejection (CHR). However, many cases lack C4d deposition and/or circulating donor-specifi c antibodies, and the contribution of other potential causes has not been fully addressed.Methods: Of 209 consecutive renal allograft indication biopsies performed for chronic allograft dysfunction, 25 that met pathologic criteria of TG (>10% duplication of the GBM without immune complex deposition) were examined for various etiologies, including hepatitis C infection (HCV), thrombotic microangiopathy (TMA), and CHR. 29 cases of biopsy-proven isolated chronic calcineurin inhibitor toxicity from the same time period were used as controls for comparing the prevalence of HCV.Results: Three partially overlapping categories accounted for 84% of the cases: C4d+TG (48%), HCV+TG (36%) and TMA+TG (32%). The majority of TMA+ cases were HCV+ (63%) and the majority of HCV+ cases had TMA (56%). Donor specifi c antibodies were associated with C4d+TG (7/8 vs. 1/4 C4d-TG; P<0.02), but not with HCV+TG. The prevalence of HCV was higher in the TG group than in 29 control patients without TG (36% vs. 7%, P<0.01). HCV+TG patients developed allograft failure earlier than HCV-TG patients (67.2 ± 60.2 mo versus 153.4 ± 126.2 mo, P=0.02). On a multivariate analysis, out of HCV, TG and C4d, only HCV was found to be a signifi cant risk factor for a more rapid allograft loss.Conclusion: We conclude that TG is not a specifi c diagnosis, but a pattern of pathologic injury with 3 major overlapping pathways involving CHR, HCV infection and TMA. It is important to distinguish these mechanisms, as they may have differentprognostic and therapeutic implications.