Hepatitis C virus and liver transplantation

T2 relaxation time is related to liver fibrosis severity

BACKGROUND

The grading of liver fibrosis relies on liver biopsy. Imaging techniques, including elastography and relaxometric, techniques have had varying success in diagnosing moderate fibrosis. The goal of this study was to determine if there is a relationship between the T2-relaxation time of hepatic parenchyma and the histologic grade of liver fibrosis in patients with hepatitis C undergoing both routine, liver MRI and liver biopsy, and to validate our methodology with phantoms and in a rat model of liver fibrosis.

METHODS

This study is composed of three parts: (I) 123 patients who underwent both routine, clinical liver MRI and biopsy within a 6-month period, between July 1999 and January 2010 were enrolled in a retrospective study. MR imaging was performed at 1.5 T using dual-echo turbo-spin echo equivalent pulse sequence. T2 relaxation time of liver parenchyma in patients was calculated by mono-exponential fit of a region of interest (ROI) within the right lobe correlating to histopathologic grading (Ishak 0-6) and routine serum liver inflammation [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)]. Statistical comparison was performed using ordinary logistic and ordinal logistic regression and ANOVA comparing T2 to Ishak fibrosis without and using AST and ALT as covariates; (II) a phantom was prepared using serial dilutions of dextran coated magnetic iron oxide nanoparticles. T2 weighed imaging was performed by comparing a dual echo fast spin echo sequence to a Carr-Purcell-Meigboom-Gill (CPMG) multi-echo sequence at 1.5 T. Statistical comparison was performed using a paired t-test; (III) male Wistar rats receiving weekly intraperitoneal injections of phosphate buffer solution (PBS) control (n=4 rats); diethylnitrosamine (DEN) for either 5 (n=5 rats) or 8 weeks (n=4 rats) were MR imaged on a Bruker Pharmascan 4.7 T magnet with a home-built bird-cage coil. T2 was quantified by using a mono-exponential fitting algorithm on multi-slice multi echo T2 weighted data. Statistical comparison was performed using ANOVA.

RESULTS

(I) Histopathologic evaluation of both rat and human livers demonstrated no evidence of steatosis or hemochromatosis There was a monotonic increase in mean T2 value with increasing degree of fibrosis (control 65.4±2.9 ms, n=6 patients); mild (Ishak 1-2) 66.7±1.9 ms (n=30); moderate (Ishak 3-4) 71.6±1.7 ms (n=26); severe (Ishak 5-6) 72.4±1.4 ms (n=61); with relatively low standard error (~2.9 ms). There was a statistically significant difference between degrees of mild (Ishak <4) vs. moderate to severe fibrosis (Ishak >4) (P=0.03) based on logistic regression of T2 and Ishak, which became insignificant (P=0.07) when using inflammatory markers as covariates. Expanding on this model using ordinal logistic regression, there was significance amongst all 4 groups comparing T2 to Ishak (P=0.01), with significance using inflammation as a covariate (P=0.03) and approaching statistical significance amongst all groups by ANOVA (P=0.07); (II) there was a monotonic increase in T2 and statistical significance (ANOVA P<0.0001) between each rat subgroup [phosphate buffer solution (PBS) 25.2±0.8, DEN 5-week (31.1±1.5), and DEN 9-week (49.4±0.4) ms]; (III) the phantoms that had T2 values within the relevant range for the human liver (e.g., 20-100 ms), demonstrated no statistical difference between two point fits on turbo spin echo (TSE) data and multi-echo CPMG data (P=0.9).

CONCLUSIONS

The finding of increased T2 with liver fibrosis may relate to inflammation that may be an alternative or adjunct to other noninvasive MR imaging based approaches for assessing liver fibrosis.

Risk factors for new onset diabetes mellitus after liver transplantation: A meta-analysis

AIM: To determine the risk factors for new-onset diabetes mellitus (NODM) after liver transplantation by conducting a systematic review and meta-analysis.

METHODS: We electronically searched the databases of MEDLINE, EMBASE and the Cochrane Library from January 1980 to December 2013 to identify relevant studies reporting risk factors for NODM after liver transplantation. Two authors independently assessed the trials for inclusion and extracted the data. Discrepancies were resolved in consultation with a third reviewer. All statistical analyses were performed with the RevMan5.0 software (The Cochrane Collaboration, Oxford, United Kingdom). Pooled odds ratios (OR) or weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated using either a fixed effects or a random effects model, based on the presence (I² < 50%) or absence (I² > 50%) of significant heterogeneity.

RESULTS: Twenty studies with 4580 patients were included in the meta-analysis, all of which were retrospective. The meta-analysis identified the following significant risk factors: hepatitis C virus (HCV) infection (OR = 2.68; 95%CI: 1.92-3.72); a family history of diabetes (OR = 1.69, 95%CI: 1.09-2.63, P < 0.00001); male gender (OR = 1.53; 95%CI: 1.24-1.90; P < 0.0001); impaired fasting glucose (IFG; OR = 3.27; 95%CI: 1.84-5.81; P < 0.0001); a family history of diabetes (OR = 1.69; 95%CI: 1.09-2.63; P = 0.02); use of tacrolimus (OR = 1.34; 95%CI: 1.03-1.76; P = 0.03) and body mass index (BMI)(WMD = 1.19, 95%CI: 0.69-1.68, P < 0.00001). Other factors, such as hepatitis B virus infection and alcoholism, were not found to be associated with the incidence of NODM.

CONCLUSION: The study showed that HCV infection, IFG, a family history of diabetes, male gender, tacrolimus and BMI are risk factors for NODM after liver transplantation.

Transplantation of bone marrow-derived mesenchymal stem cells after regional hepatic irradiation ameliorates thioacetamide-induced liver fibrosis in rats

BACKGROUND

Recent studies have demonstrated that bone marrow-derived mesenchymal stem cells (BM-MSCs) can potentially revert liver fibrosis, but it is not known if preparative hepatic irradiation (HIR) contributes to the therapeutic effect of transplanted BM-MSCs. In this study, we investigate the effects of HIR on transplanted BM-MSCs in cirrhotic rats and the underlying mechanism by which mesenchymal stem cells (MSCs) relieve liver fibrosis.

MATERIALS AND METHODS

The BM-MSCs from male rats were labeled with CM-Dil and injected via portal vein into two groups of thioacetamide-induced cirrhotic rats, and the controls were injected with the same volume of saline. The right hemiliver of one cirrhotic rat group was irradiated (15 Gy) 4 d before transplantation. Liver function tests and histologic experiments were performed, and the liver population of BM-MSCs was estimated.

RESULTS

The transplantation of MSCs alleviated liver fibrosis and reduced expression of transforming growth factor-β1, Smad2, collagen type I, and α-SMA. HIR preconditioning promoted homing and repopulation of MSCs and resulted in better treatment outcomes.

CONCLUSIONS

HIR preconditioning enhances the effect of BM-MSCs in improving thioacetamide-induced liver fibrosis in rats by promoting their homing and repopulation. BM-MSCs may function by inhibiting transforming growth factor-β1-Smad signaling pathway in the liver.

Pegylated interferon-alfa-2a monotherapy in patients infected with HCV genotype 2 and importance of rapid virological response

BACKGROUND

Pegylated (PEG)-interferon (IFN)-alfa-2a plus ribavirin (RBV) therapy for 24 weeks is now a standard treatment protocol for patients with hepatitis C virus (HCV) genotype 2. As RBV cannot be used in certain situations, we examined whether PEG-IFN-alfa-2a monotherapy for 24 weeks or less would be sufficient to obtain a sustained virological response (SVR) in patients infected with HCV genotype 2.

METHODS

Forty-nine consecutive patients with HCV genotype 2 received PEG-IFN-alfa-2a (180 μg/week) subcutaneously without oral RBV for 8-64 weeks. HCV RNA level was determined by COBAS AMPLICOR HCV Test, v2.0.

RESULTS

HCV RNA was equal to or less than 100 KIU/mL (defined as low viral load) in 15 of 49 patients, and the remaining 34 had HCV RNA above 100 KIU/mL (defined as high viral load). All 15 patients with low viral load achieved rapid virological response (RVR; HCV RNA negative at week 4), and also achieved SVR with an average treatment duration of 17.1 weeks. The 34 patients with high viral load were treated for 33.7 weeks on average, and 19 of them (55.9%) achieved RVR. The SVR rates of these patients were significantly higher in those with RVR than without RVR (16/19 vs. 6/15 p = 0.0074).

CONCLUSION

PEG-IFN-alfa-2a monotherapy for 24 weeks or less might be sufficient to treat selected patients with HCV genotype 2, especially those with low viral load and becoming negative for HCV RNA by week 4 of treatment.

Quantification of hepatitis C virus in patients treated with peginterferon-alfa 2a plus ribavirin treatment by COBAS TaqMan HCV test

Extremely low levels of serum hepatitis C virus (HCV) RNA can be detected by COBAS TaqMan HCV test. To investigate whether the COBAS TaqMan HCV test is useful for measuring rapid virological response (RVR) and early virological response (EVR) to predict sustained virological response (SVR), we compared the virological response to PEG-IFN-alfa 2a plus RBV in 76 patients infected with HCV genotype 1 when undetectable HCV RNA by the COBAS TaqMan HCV test was used, with those when below 1.7 log IU/mL HCV RNA by COBAS TaqMan HCV test was used, which corresponded to the use of traditional methods. Among the 76 patients, 28 (36.8%) had SVR, 13 (17.1%) relapsed, 19 (25.0%) did not respond, and 16 (21.0%) discontinued the treatment due to side effects. The positive predictive values for SVR based on undetectable HCV RNA by COBAS TaqMan HCV test at 24 weeks after the end of treatment [10/10 (100%) at week 4, 21/23 (91.3%) at week 8 and 26/33 (78.7%) at week 12] were superior to those based on <1.7 log IU/mL HCV RNA [17/19 (89.4%) at week 4, 27/38 (71.0%) at week 8, and 27/43 (62.7%) at week 12]. The negative predictive values for SVR based on <1.7 log IU/mL HCV RNA by COBAS TaqMan HCV test [46/57 (80.7%) at week 4, 37/38 (97.3%) at week 8, and 32/33 (96.9%) at week 12] were superior to those based on undetectable HCV RNA [48/66 (72.7%) at week 4, 46/53 (86.7%) at week 8, and 41/43 (95.3%) at week 12]. The utilization of both undetectable RNA and <1.7 log IU/mL HCV RNA by COBAS TaqMan HCV test is useful and could predict SVR and non-SVR patients with greater accuracy.

New onset diabetes mellitus after liver transplantation and hepatitis C virus infection: meta-analysis of clinical studies

New onset diabetes mellitus (NODM) postliver transplantation (LT) is very common and may negatively affect patient and graft survival, but its causative mechanism is still unclear. This study was to analyze the connection between Hepatitis C virus (HCV) infection and NODM after LT by systematically reviewing published medical literature. We electronically searched databases of MEDLINE, EMBASE and the Cochrane Library from January 1980 to January 2008. Only retrospective studies could be identified. Seven of them were subjected to the meta-analysis. Analysis was performed by using revman 4.2 software. We found that HCV increased the prevalence of NODM [OR 2.46; 95%CI (1.44, 4.19)]. Then, we further analyzed the association between HCV and persistent-NODM (P-NODM) after LT. The result showed that prevalence of P-NODM was higher in HCV-positive group than in HCV-negative group with marginally statistical significance [OR = 1.39; 95%CI (1.06, 1.83)]. The present meta-analysis based on retrospective studies suggested a significant relationship between HCV and NODM after LT, and it seems that HCV infection might also increase the prevalence of P-NODM. Multicenter, large sized prospective studies are still needed to further confirm these results.

Matrix metalloproteinase gene delivery for liver fibrosis

The resolution of advanced liver fibrosis has been recently recognized to be possible, if the causative stimuli are successfully removed. However, whether complete resolution from cirrhosis, the end stage of liver fibrosis, can be achieved is still questionable. Delivery of interstitial collagenases, such as matrix metalloproteinase (MMP)-1, in the liver could be an attractive strategy to treat advanced hepatic fibrosis from the view point that the imbalance between too few interstitial collagenases and too many of their inhibitors is the main obstacle to the resolution from fibrosis. Remodeling of hepatic extracellular matrix by delivered interstitial collagenases also facilitates the disappearance of activated hepatic stellate cells, the main matrix-producing cells in the liver, and promotes the proliferation of hepatocytes. This review will focus on the impact of the gene delivery of MMPs for the treatment of advanced liver fibrosis while discussing other current therapeutic strategies for liver fibrosis, and on the need for the development of a safe and effective delivery system of MMPs.

A comparison of liver transplantation outcomes in the pre- vs. post-MELD eras

BACKGROUND

The model for end stage liver disease (MELD)-based organ allocation system is designed to prioritize orthotopic liver transplantation (OLT) for patients with the most severe liver disease. However, there are no published data to confirm whether this goal has been achieved or whether the policy has affected long-term post-OLT survival.

AIM

To compare pre-OLT liver disease severity and long-term (1 year) post-OLT survival between the pre- and post-MELD eras.

METHODS

Using the United Network of Organ Sharing database, we compared two cohorts of adult patients undergoing cadaveric liver transplant in the pre-MELD (n = 3857) and post-MELD (n = 4245) eras. We created multivariable models to determine differences in: (i) pre-OLT liver disease severity as measured by MELD; and (ii) 1-year post-OLT outcomes.

RESULTS

Patients undergoing OLT in the post-MELD era had more severe liver disease at the time of transplantation (mean MELD = 20.5) vs. those in the pre-MELD era (mean MELD = 17.0). There were no differences in the unadjusted patient or graft survival at 1 year post-OLT. This difference remained insignificant after adjusting for a range of prespecified recipient, donor, and transplant centre-related factors in multivariable survival analysis.

CONCLUSIONS

Although liver disease severity is higher in the post- vs. pre-MELD era, there has been no change in long-term post-OLT patient or graft survival. These results indicate that the MELD era has achieved its primary goals by allocating cadaveric livers to the sickest patients without compromising post-OLT survival.

Hepatitis C virus is independently associated with increased insulin resistance after liver transplantation

BACKGROUND AND AIMS

There is a strong epidemiologic association between diabetes mellitus (DM) and hepatitis C virus (HCV) infection. However, the pathogenetic basis for this association has not been established. We sought to evaluate the association between insulin resistance (IR), beta-cell dysfunction, and HCV among orthotopic liver transplant (OLT) recipients.

METHODS

We performed a cross sectional analysis comparing 39 HCV(+) with 60 HCV(-) OLT recipients. IR and beta-cell function were calculated using validated measures and were correlated with clinical variables.

RESULTS

By multivariate analysis of the entire cohort, HCV infection and body mass index (BMI) were independent predictors of IR (P =0.04 and 0.0006, respectively). HCV infection was associated with 35% increase in IR. Because the model used to calculate IR was derived from nondiabetic subjects, we performed additional analysis of patients who did not meet criteria for diabetes at the time of their study evaluation. In this analysis, HCV(+) subjects had greater fasting insulin and homeostasis model assessment (HOMA) IR (15.3 mu U/mL and 3.8) compared with HCV(-) patients (10.7 mu U/mL and 2.5) (P =0.03, 0.03). There was no difference in beta-cell function or hepatic insulin extraction between the HCV (+) and (-) groups. HCV (P =0.0005), BMI (P <0.0001), and high high-density lipoprotein (P =0.039) were the only independent predictors of IR. The presence of HCV infection and a 10-fold increase in HCV RNA were associated with a 62% and 8% increase in IR, respectively.

CONCLUSIONS

HCV is independently associated with increased IR after OLT. These findings provide a possible pathogenetic basis for the association of DM with HCV.

[52-year-old patient with subcutaneous space-occupying lesion in immunosuppression]

We report the case of a 52-years-old male patient, who was diagnosed with subcutaneous alveolar echinococcosis 6 months after liver transplantation for HCV-related cirrhosis. Nether the explanted nor the transplantated liver revealed an echinococcus focus. Therefore a rare primary extrahepatic manifestation was likely. Interestingly, the echinococcal larvae had developed protoscolices. The development of mature tapeworms in human is a rarity, which could be related to the immunosuppressive therapy after liver transplantation. The patient was curatively treated by surgical removal of the subcutaneous tumor and a postoperative therapy with albendazole. Furthermore, HCV reinfection (genotype 2b) was successfully treated with interferone alpha 2b and ribavirine for 6 months.

Biotechnology and drug discovery: from bench to bedside

New biotechnology and drug discovery technologies are facilitating the rapid expansion of the clinical drug chest, empowering clinicians with a better understanding of disease as well as novel modalities for treating patients. Important research tools and themes include genomics, proteomics, ligand-receptor interaction, signal transduction, rational drug design, biochips, and microarrays. Emerging drug classes include monoclonal antibodies, cancer vaccines, gene therapy, antisense strands, enzymes, and proteins. In this article, we review these topics and illustrate their potential impact by presenting an overview of promising drugs in the pipeline. Clinicians who use these novel treatments must become familiar with these trends.

Polymorphisms in cytokines and growth factor genes and their association with acute rejection and recurrence of hepatitis C virus disease in liver transplantation

Acute rejection (AR) and recurrence of hepatitis C virus (HCV) infection are complications after liver transplantation (LTx). Genetic factors play a role in cytokine production as a consequence of polymorphisms within cytokine genes. Our goal was to identify genetic factors that might be associated with AR and recurrence of HCV in liver transplant recipients (LTxRs). We studied 77 Caucasian LTxRs and 100 Caucasian healthy individuals. We studied single-nucleotide polymorphisms (SNPs) in tumor necrosis factor-alpha[TNF-alpha, interleukin-6 (IL-6), IL-10, transforming growth factor-beta1, and angiotensin-converting enzyme genes by SNaPSHOT trade mark Multiplex assay. SNPs were classified as high producers (HP), intermediate producers (IP), or low producers (LP), and their association with AR and recurrence of HCV were studied. The frequency of TNF-alpha IP and HP genotypes was significantly higher in LTxRs with AR in comparison to patients without AR (TNF-alpha HP -238: 63 vs 20%, p < 0.001; TNF-alpha HP -308: 47.4 vs 20%, p = 0.02). The frequency of IL-6 IP and HP genotypes was higher in patients with AR episodes, but the difference was not statistically significant (p = 0.14). However, when we analyzed the simultaneous presence of pro-inflammatory genotypes in the same patient, we found a significant difference between patients with and without AR, respectively (42.1 vs 14.6%, p = 0.012). Moreover, the frequency of the IL-10 LP genotype was higher in LTx patients with AR (p = 0.001) compared to patients without AR. There was an association between pro-inflammatory genotypes and HCV recurrence. Our data suggest that cytokine gene polymorphisms might play a role in AR and HCV recurrence in LTxRs.

Controversies in the management of hepatitis C virus infection after liver transplantation

Recurrence of hepatitis C virus infection after liver transplantation is universal. A significant percentage of these patients develop progressive graft injury and cirrhosis. Those factors that modulate disease progression in liver transplant recipients with recurrent hepatitis C virus infection remain controversial and are poorly understood. Treatment of recurrent hepatitis C virus after liver transplantation with either interferon or interferon and ribavirin has yielded only limited success. Regardless of this, treatment is instituted. Peginterferon is more effective than standard interferon for treatment of chronic hepatitis C virus infection in the nontransplantation setting when used either alone or with ribavirin. The effectiveness of peginterferon, both with and without ribavirin in the posttransplantation setting, is currently being explored. In this review those factors thought to affect disease progression in patients with recurrent hepatitis C virus will be discussed, strategies that have been used to treat recurrent hepatitis C virus will be reviewed, and the impact that peginterferon may have on hepatitis C virus infection in the pretransplantation and posttransplantation setting will be explored.

Promising candidates for the treatment of chronic hepatitis C

Chronic hepatitis C virus (HCV) infection is the cause of an emerging global pandemic of chronic liver disease. Current pegylated IFN-alpha/ribavirin combination therapies are merely 54 - 56% efficacious and are often poorly tolerated. Popular strategies to improve upon existing therapies include efforts to decrease the dosing regime, improve the safety profile and specifically target the liver, the site of HCV replication. A clear goal of novel therapies is to significantly improve the therapeutic response for HCV-infected patients. One popular scheme to accomplish this is to directly target the viral enzymes involved in HCV RNA replication. While peptidomimetics have been pursued as potent and specific inhibitors of the serine protease, nucleoside analogues and non-nucleoside small molecules have been explored as RNA-dependent RNA polymerase inhibitors with promising potential. Advances in the understanding of HCV replication at the molecular level that stem from the use of the subgenomic replicon system, in vitro enzyme assays and from co-crystallographic structure solutions of the replication enzymes with novel inhibitors have propelled these compounds into clinical development. As these candidates are developed further, there is great hope for a cure for all those chronically infected with HCV.

Hepatitis C: magnitude of the problem

1. End-stage liver disease associated with hepatitis C virus (HCV) infection has become the leading indication for liver transplantation in the United States. 2. Patients with end-stage liver disease caused by HCV may have such associated comorbidities as chronic alcoholism, steatosis, or coinfection with human immunodeficiency virus 1 or other hepatitis viruses. These comorbidities may accelerate disease progression. 3. As chronic hepatitis C progresses to cirrhosis, the risk for the development of hepatocellular carcinoma increases; this poses difficult management problems. 4. As patients who underwent transplantation for end-stage liver disease caused by HCV infection are followed up long term, it has become clear that patient and graft survival are decreased compared with HCV-negative patients or those with cholestatic liver disorders. 5. Risk factors associated with a worse outcome after transplantation include host, viral, donor, and posttransplantation factors. 6. Major challenges to be addressed in the future include delineation of the optimal antiviral therapy and how to handle the need to perform retransplantation on patients who develop graft dysfunction as a result of HCV recurrence.