Cyclosporine suppresses hepatitis C virus in vitro and increases the chance of a sustained virological response after liver transplantation

The Ca2+-dependent phosphatase calcineurin dephosphorylates TBK1 to suppress antiviral innate immunity

Tumor necrosis factor receptor-associated factor family member-associated NF-κB activator-binding kinase 1 (TBK1) plays a key role in the induction of the type 1 interferon (IFN-I) response, which is an important component of innate antiviral defense. Viruses target calcium (Ca2+) signaling networks, which participate in the regulation of the viral life cycle, as well as mediate the host antiviral response. Although many studies have focused on the role of Ca2+ signaling in the regulation of IFN-I, the relationship between Ca2+ and TBK1 in different infection models requires further elucidation. Here, we examined the effects of the Newcastle disease virus (NDV)-induced increase in intracellular Ca2+ levels on the suppression of host antiviral responses. We demonstrated that intracellular Ca2+ increased significantly during NDV infection, leading to impaired IFN-I production and antiviral immunity through the activation of calcineurin (CaN). Depletion of Ca²+ was found to lead to a significant increase in virus-induced IFN-I production resulting in the inhibition of viral replication. Mechanistically, the accumulation of Ca2+ in response to viral infection increases the phosphatase activity of CaN, which in turn dephosphorylates and inactivates TBK1 in a Ca2+-dependent manner. Furthermore, the inhibition of CaN on viral replication was counteracted in TBK1 knockout cells. Together, our data demonstrate that NDV hijacks Ca2+ signaling networks to negatively regulate innate immunity via the CaN-TBK1 signaling axis. Thus, our findings not only identify the mechanism by which viruses exploit Ca2+ signaling to evade the host antiviral response but also, more importantly, highlight the potential role of Ca2+ homeostasis in the viral innate immune response.IMPORTANCEViral infections disrupt intracellular Ca2+ homeostasis, which affects the regulation of various host processes to create conditions that are conducive for their own proliferation, including the host immune response. The mechanism by which viruses trigger TBK1 activation and IFN-I induction through viral pathogen-associated molecular patterns has been well defined. However, the effects of virus-mediated Ca2+ imbalance on the IFN-I pathway requires further elucidation, especially with respect to TBK1 activation. Herein, we report that NDV infection causes an increase in intracellular free Ca2+ that leads to activation of the serine/threonine phosphatase CaN, which subsequently dephosphorylates TBK1 and negatively regulates IFN-I production. Furthermore, depletion of Ca2+ or inhibition of CaN activity exerts antiviral effects by promoting the production of IFN-I and inhibiting viral replication. Thus, our results reveal the potential role of Ca2+ in the innate immune response to viruses and provide a theoretical reference for the treatment of viral infectious diseases.

Immunosuppression in the Management of Presumed Non-infective Uveitis; Are We Sure What We are Treating? Notes on the Antimicrobial Properties of the Systemic Immunosuppressants

PURPOSE

To describe the antimicrobial effects of immunosuppressants used for presumed autoimmune uveitis, and to discuss the potential importance of these effects in the context of increasing knowledge of the human microbiomes and their influence on inflammation.

METHODS

Literature review.

REVIEW OF EVIDENCE

All immunosuppressants have intrinsic antimicrobial effects; these vary considerably between drugs, and include antibacterial, antiviral and antifungal action. Immunosuppression is known to affect the composition of the gut microbiome, and alterations in microbiome composition are known to affect inflammations including uveitis.

CONCLUSIONS

Oral immunosuppressants are assumed to act on presumed autoimmune uveitis by downregulation of, or other interference with, an aberrant immune response. However, their antimicrobial properties are usually forgotten, and in the context of increasing knowledge of the involvement of microbes in the initiation of, and also potentially the perpetuation of, tissue inflammation, these effects may prove to be a fundamental part of their action.

Pre-emptive Treatment of HCV after Living Donor Liver Transplantation with Direct-Acting Antiviral Agents

BACKGROUND

Hepatitis C virus (HCV) universally recurs after liver transplantation (LT). Although the introduction of direct-acting antiviral agents (DAAs) has revolutionized the treatment of HCV infection, no optimal treatment for HCV recurrence after LT has been developed.

METHODS

This study retrospectively evaluated the efficacy of DAAs as a pre-emptive treatment for recurrent HCV infection after living donor liver transplantation (LDLT). From January 2010 to December 2016, 70 patients received pegylated interferon (PegIFN) and 35 patients were treated with DAA-based regimens to treat recurrent HCV after LDLT. All antiviral treatments were pre-emptive.

RESULTS

Genotype 1b was the most common HCV type (61.9%). Twenty-two recipients in the DAA group were treated with ledipasvir/sofosbuvir, nine received daclatasvir plus asunaprevir, three received sofosbuvir, and one received sofosbuvir plus daclatasvir. All 35 patients (100%) in the DAA group achieved a sustained virologic response (SVR), a percentage significantly higher than that (71.4%) in the PegIFN group (p < 0.001). In the PegIFN group, the 1-, 3-, and 5-year graft survival rates were 85.7, 73.9, and 70.7%, respectively, whereas those in the DAA group were 100, 100, and 100%, respectively (p = 0.008).

CONCLUSION

DAA-based regimens are an effective treatment for HCV recurrence after LDLT, resulting in an improved SVR and better graft survival than PegIFN.

Kisspeptin/GPR54 signaling restricts antiviral innate immune response through regulating calcineurin phosphatase activity

G protein-coupled receptor 54 (GPR54), the key receptor for the neuropeptide hormone kisspeptin, plays essential roles in regulating puberty development and cancer metastasis. However, its role in the antiviral innate immune response is unknown. We report that virus-induced type I interferon (IFN-I) production was significantly enhanced in Gpr54-deficient cells and mice and resulted in restricted viral replication. We found a marked increase of kisspeptin in mouse serum during viral infection, which, in turn, impaired IFN-I production and antiviral immunity through the GPR54/calcineurin axis. Mechanistically, kisspeptin/GPR54 signaling recruited calcineurin and increased its phosphatase activity to dephosphorylate and deactivate TANK [tumor necrosis factor receptor-associated factor (TRAF) family member-associated NF-κB activator]-binding kinase 1 (TBK1) in a Ca²⁺-dependent manner. Thus, our data reveal a kisspeptin/GPR54/calcineurin-mediated immune evasion pathway exploited by virus through the negative feedback loop of TBK1 signaling. These findings also provide insights into the function and cross-talk of kisspeptin, a known neuropeptide hormone, in antiviral innate immune response.

Novel activities of safe-in-human broad-spectrum antiviral agents

According to the WHO, there is an urgent need for better control of viral diseases. Re-positioning existing safe-in-human antiviral agents from one viral disease to another could play a pivotal role in this process. Here, we reviewed all approved, investigational and experimental antiviral agents, which are safe in man, and identified 59 compounds that target at least three viral diseases. We tested 55 of these compounds against eight different RNA and DNA viruses. We found novel activities for dalbavancin against echovirus 1, ezetimibe against human immunodeficiency virus 1 and Zika virus, as well as azacitidine, cyclosporine, minocycline, oritavancin and ritonavir against Rift valley fever virus. Thus, the spectrum of antiviral activities of existing antiviral agents could be expanded towards other viral diseases.

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339 approved, investigational and experimental safe-in-human antivirals were identified.

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59 compounds, which target ≥3 viral diseases, were selected.

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55 of the 59 compounds were tested against 8 RNA and DNA viruses.

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7 compounds were found to possess novel antiviral activities.

The influence of immunosuppressants on direct-acting antiviral therapy is dependent on the hepatitis C virus genotype

BACKGROUND

Direct-acting antivirals (DAAs) have substantially increased sustained virological response rates after liver transplantation, with improved tolerance compared to interferon-based therapy. The influence of immunosuppressive agents on the efficacy of DAAs has not been clarified.

METHODS

Subgenomic hepatitis C virus (HCV) replicons for genotype (GT) 1b, 2b, 3a, and 4a were treated with the mammalian target of rapamycin (mTOR) inhibitors everolimus and sirolimus or with the calcineurin inhibitors (CNIs) cyclosporine or tacrolimus, either alone or in combination with selected DAAs. Cell proliferation-related effects were excluded with MTT assays. HCV replication activity was quantified by quantitative real-time polymerase chain reaction or luciferase assay.

RESULTS

Addition of either mTOR inhibitor to the DAA daclatasvir (DAC) resulted in a 30% increase in antiviral activity compared to DAC alone for HCV GT2a, GT3a, and GT4a (all P ≤ .01). Similar results were obtained using sofosbuvir and ledipasvir. In contrast, addition of either mTOR inhibitor to DAC induced a 30% reduction in antiviral activity in GT1b cells (P ≤ .01 vs DAC alone). Neither CNI affects the antiviral activity of the DAAs in any HCV GT.

CONCLUSION

For patients with HCV GT2a, GT3a, or GT4a infection, mTOR-based immunosuppressive therapy may be beneficial. CNI-based therapy may be more efficacious in GT1b patients, as mTOR inhibitors seem to impair antiviral efficacy of DAAs in HCV GT1b infection.

A delicate balance between rejection and BK polyomavirus associated nephropathy; A retrospective cohort study in renal transplant recipients

BACKGROUND

The immunosuppressive agents mycophenolate acid (MPA) and tacrolimus (Tac) are associated with a higher incidence of BK polyomavirus nephropathy (BKPyVAN). In this observational retrospective cohort study, the frequency of BK polyomavirus (BKPyV) complications over a 24-month period was studied.

METHODS

358 renal transplant recipients (RTR) treated with MPA, with either cyclosporine A (CsA) (CsAM group) or Tac (TacM group) and mostly prednisolone, were included.

RESULTS

Incidence of BKPyV-viremia was not significantly different between the CsAM (n = 42/191) (22.0%) and the TacM (n = 36/167) (21.6%) group. Biopsy proven BKPyVAN occurred more often in the TacM group (6.6%) versus the CsAM group (2.1%) (p = 0.03). Longitudinal data analysis showed a significant earlier decline of viral load in plasma in the CsAM group compared to the TacM group (p = 0.005). The incidence of biopsy proven acute rejection (BPAR) was significantly higher in the CsAM (19.9%) compared to the TacM (10.8%) (p = 0.02) group. Graft loss, estimated glomerular filtration rate and mortality rate did not differ in both treatment groups.

CONCLUSION

In conclusion, this study shows that immunosuppressive treatment with Tac and MPA compared to CsA and MPA is associated with a lower incidence of BPAR, but at the cost of an increased risk of developing BKPyVAN in the first two years post-transplant.

Maintenance immunosuppression for adults undergoing liver transplantation: a network meta-analysis

BACKGROUND

As part of liver transplantation, immunosuppression (suppressing the host immunity) is given to prevent graft rejections resulting from the immune response of the body against transplanted organ or tissues from a different person whose tissue antigens are not compatible with those of the recipient. The optimal maintenance immunosuppressive regimen after liver transplantation remains uncertain.

OBJECTIVES

To assess the comparative benefits and harms of different maintenance immunosuppressive regimens in adults undergoing liver transplantation through a network meta-analysis and to generate rankings of the different immunosuppressive regimens according to their safety and efficacy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and trials registers until October 2016 to identify randomised clinical trials on immunosuppression for liver transplantation.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or publication status) in adult participants undergoing liver transplantation (or liver retransplantation) for any reason. We excluded trials in which participants had undergone multivisceral transplantation or participants with established graft rejections. We considered any of the various maintenance immunosuppressive regimens compared with each other.

DATA COLLECTION AND ANALYSIS

We performed a network meta-analysis with OpenBUGS using Bayesian methods and calculated the odds ratio, rate ratio, and hazard ratio (HR) with 95% credible intervals (CrI) based on an available-case analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance.

MAIN RESULTS

We included a total of 26 trials (3842 participants) in the review, and 23 trials (3693 participants) were included in one or more outcomes in the review. The vast majority of the participants underwent primary liver transplantation. All of the trials were at high risk of bias, and all of the evidence was of low or very low quality. In addition, because of sparse data involving trials at high risk of bias, it is not possible to entirely rely on the results of the network meta-analysis. The trials included mainly participants undergoing primary liver transplantation of varied aetiologies. The follow-up in the trials ranged from 3 to 144 months. The most common maintenance immunosuppression used as a control was tacrolimus. There was no evidence of difference in mortality (21 trials; 3492 participants) or graft loss (15 trials; 2961 participants) at maximal follow-up between the different maintenance immunosuppressive regimens based on the network meta-analysis. In the direct comparison, based on a single trial including 222 participants, tacrolimus plus sirolimus had increased mortality (HR 2.76, 95% CrI 1.30 to 6.69) and graft loss (HR 2.34, 95% CrI 1.28 to 4.61) at maximal follow-up compared with tacrolimus. There was no evidence of differences in the proportion of people with serious adverse events (1 trial; 719 participants), proportion of people with any adverse events (2 trials; 940 participants), renal impairment (8 trials; 2233 participants), chronic kidney disease (1 trial; 100 participants), graft rejections (any) (16 trials; 2726 participants), and graft rejections requiring treatment (5 trials; 1025 participants) between the different immunosuppressive regimens. The network meta-analysis showed that the number of adverse events was lower with cyclosporine A than with many other immunosuppressive regimens (12 trials; 1748 participants), and the risk of retransplantation (13 trials; 1994 participants) was higher with cyclosporine A than with tacrolimus (HR 3.08, 95% CrI 1.13 to 9.90). None of the trials reported number of serious adverse events, health-related quality of life, or costs.

FUNDING

14 trials were funded by pharmaceutical companies who would benefit from the results of the trial; two trials were funded by parties who had no vested interest in the results of the trial; and 10 trials did not report the source of funding.

AUTHORS' CONCLUSIONS

Based on low-quality evidence from a single small trial from direct comparison, tacrolimus plus sirolimus increases mortality and graft loss at maximal follow-up compared with tacrolimus. Based on very low-quality evidence from network meta-analysis, we found no evidence of difference between different immunosuppressive regimens. We found very low-quality evidence from network meta-analysis and low-quality evidence from direct comparison that cyclosporine A causes more retransplantation compared with tacrolimus. Future randomised clinical trials should be adequately powered; performed in people who are generally seen in the clinic rather than in highly selected participants; employ blinding; avoid postrandomisation dropouts or planned cross-overs; and use clinically important outcomes such as mortality, graft loss, renal impairment, chronic kidney disease, and retransplantation. Such trials should use tacrolimus as one of the control groups. Moreover, such trials ought to be designed in such a way as to ensure low risk of bias and low risks of random errors.

Pharmacokinetics of drugs in adult living donor liver transplant patients: regulatory factors and observations based on studies in animals and humans

INTRODUCTION

Limited information is available on the pharmacokinetics of drugs in the donors and recipients following adult living donor liver transplantation (LDLT). Given that both the donors and recipients receive multiple drug therapies, it is important to assess the pharmacokinetics of drugs used in these patients.

AREAS COVERED

Pathophysiological changes that occur post-surgery and regulatory factors that may influence pharmacokinetics of drugs, especially hepatic drug metabolism and transport in both LDLT donors and the recipients are discussed. Pharmacokinetic data in animals with partial hepatectomy are presented. Clinical pharmacokinetic data of certain drugs in LDLT recipients are further reviewed.

EXPERT OPINION

It takes up to six months for the liver volume to return to normal after LDLT surgery. In the LDLT recipients, drug exposure generally is higher with lower clearance during early period post-transplant; lower initial dosages of immunosuppressants are used than deceased donor liver transplant recipients during the first six months post-transplantation. In animals, the activities of hepatic drug metabolizing enzymes and transporters are known to be altered differentially during liver regeneration. Future studies on the actual hepatic function with reference to drug metabolism, drug transport, and biliary secretion in both LDLT donors and recipients are required.

Response-Guided Therapy for Hepatitis C Virus Recurrence Based on Early Protocol Biopsy after Liver Transplantation

Hepatitis C virus (HCV) recurrence after liver transplantation (LT) is universal and progressive. Here, we report recent results of response-guided therapy for HCV recurrence based on early protocol biopsy after LT. We reviewed patients who underwent LT for HCV related liver disease between 2010 and 2012. Protocol biopsies were performed at 3, 6, and 12 months after LT in HCV recurrence (positive HCV-RNA). For any degree of fibrosis, ≥ moderate inflammation on histology or HCV hepatitis accompanying with abnormal liver function, we treated with pegylated interferon and ribavirin. We adjusted treatment period according to individual response to treatment. Among 41 HCV related recipients, 25 (61.0%) who underwent protocol biopsies more than once were enrolled in this study. The mean follow-up time was 43.1 (range, 23-55) months after LT. Genotype 1 and 2 showed in 56.0% and 36.0% patients, respectively. Of the 25 patients, 20 (80.0%) started HCV treatment after LT. Rapid or early virological response was observed in 20 (100%) patients. Fifteen (75.0%) patients finished the treatment with end-of-treatment response. Sustained virological response (SVR) was in 11 (55.0%) patients, including 5 (41.7%) of 12 genotype 1 and 6 (75.0%) of 8 non-genotype 1 (P = 0.197). Only rapid or complete early virological response was a significant predictor for HCV treatment response after LT (100% in SVR group vs. 55.6% in non-SVR group, P = 0.026). Overall 3-yr survival rate was 100%. In conclusion, response-guided therapy for HCV recurrence based on early protocol biopsy after LT shows encouraging results.

Pituitary tumor transforming gene as a novel regulatory factor of liver fibrosis

AIMS

Pituitary tumor-transforming gene (PTTG) is involved in multiple cellular pathways. We studied the development of liver fibrosis induced by thioacetamide (TAA) in knockout (PTTG-/-) and wildtype (PTTG+/+) mice.

MAIN METHODS

Liver fibrosis in PTTG+/+ and PTTG-/- mice was induced by escalating dose TAA treatment (50-400mg/kg, i.p.) for 12 weeks and assessed by histochemistry, immunohistochemistry, liver hydroxyproline, serum fibrosis markers and fibrosis-related mRNA expression by real-time PCR determination.

KEY FINDINGS

Both PTTG+/+ and PTTG-/- mice treated with TAA developed signs of fibrosis and inflammatory cell infiltration. However, histological signs of bridging fibrosis and connective tissue square morphometry were significantly attenuated in mice lacking PTTG. α-SMA immunohistochemistry revealed that hepatic stellate cell activation was markedly reduced in PTTG-/- mice compared to wildtype controls. Hepatic hydroxyproline levels were significantly lower in fibrotic PTTG-/- group. The serum TNFα and hepatic TNFα mRNA expression were significantly lower in fibrotic PTTG-/- animals, as well as hepatic TGFβ and VEGF mRNA levels compared to TAA-treated wildtype controls. Serum hyaluronate and TGFβ levels were markedly elevated in fibrotic mice of both genotypes, but were not altered by the absence of PTTG.

SIGNIFICANCE

TAA-induced fibrosis development is significantly ameliorated in PTTG-/- mice. These animals demonstrated diminished stellate cell activation, suppressed circulating serum markers of inflammation, fibrogenesis and angiogenesis. The presented findings suggest that PTTG is functionally required for hepatic fibrosis progression in an animal model of chronic liver injury. PTTG can be considered as a new important target for prevention and treatment of liver fibrosis/cirrhosis.

Tacrolimus-based versus cyclosporine-based immunosuppression in hepatitis C virus-infected patients after liver transplantation: a meta-analysis and systematic review

Background

Most liver transplant recipients receive calcineurin inhibitors (CNIs), especially tacrolimus and cyclosporine, as immunosuppressant agents to prevent rejection. A controversy exists as to whether the outcomes of hepatitis C virus (HCV)-infected liver transplant patients differ based on the CNIs used. This meta-analysis compares the clinical outcomes of tacrolimus-based and cyclosporine-based immunosuppression, especially cases of HCV recurrence in liver transplant patients with end-stage liver disease caused by HCV infection.

Methods

Related articles were identified from the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, Medline, and Embase. Meta-analyses were performed for the results of homogeneous studies.

Results

Nine randomized or quasi-randomized controlled trials were included. The total effect size of mortality (RR = 0.98, 95% CI: 0.77–1.25, P = 0.87) and graft loss (RR = 1.05, 95% CI: 0.83–1.33, P = 0.67) showed no significant difference between the two groups irrespective of duration of immunosuppressant therapy after liver transplantation. In addition, the HCV recurrence-induced mortality (RR = 1.11, 95% CI: 0.66–1.89, P = 0.69), graft loss (RR = 1.62, 95% CI: 0.64–4.07, P  = 0.31) and retransplantation (RR = 1.40, 95% CI: 0.48–4.09, P = 0.54), as well as available biopsies, confirmed that histological HCV recurrences (RR =  0.92, 95% CI: 0.71–1.19, P = 0.51) were similar.

Conclusion

These results suggested no difference in posttransplant HCV recurrence-induced mortality, graft loss and retransplantation, as well as histological HCV recurrence in patients treated with tacrolimus-based and cyclosporine-based immunosuppresion.

Natural history, treatment and prevention of hepatitis C recurrence after liver transplantation: Past, present and future

Hepatitis C virus (HCV)-related liver disease, including cirrhosis and hepatocellular carcinoma is the main indication for liver transplantation (LT) worldwide. Post-transplant HCV re-infection is almost universal and results in accelerated progression from acute hepatitis to chronic hepatitis, and liver cirrhosis. Comprehension and treatment of recurrent HCV infection after LT have been major issues for all transplant hepatologists and transplant surgeons for the last decades. The aim of this paper is to review the evolution of our knowledge on the natural history of HCV recurrence after LT, including risk factors for disease progression, and antiviral therapy. We will focus our attention on possible ways (present and future) to improve the final long-term results of LT for HCV-related liver disease.

Recurrent hepatitis C after liver transplant

End stage liver disease from hepatitis C is the most common indication for liver transplantation in many parts of the world accounting for up to 40% of liver transplants. Antiviral therapy either before or after liver transplantation is challenging due to side effects and lower efficacy in patients with cirrhosis and liver transplant recipients, as well as from drug interactions with immunosuppressants. Factors that may affect recurrent hepatitis C include donor age, immunosuppression, IL28B genotype, cytomegalovirus infection, and metabolic syndrome. Older donor age has persistently been shown to have the greatest impact on recurrent hepatitis C. After liver transplantation, distinguishing recurrent hepatitis C from acute cellular rejection may be difficult, although the development of molecular markers may help in making the correct diagnosis. The advent of interferon free regimens with direct acting antiviral agents that include NS3/4A protease inhibitors, NS5B polymerase inhibitors and NS5A inhibitors holds great promise in improving outcomes for liver transplant candidates and recipients.

Severe fibrosis in patients with recurrent hepatitis C after liver transplantation: a French experience on 250 patients over 15 years (the Orfèvre study)

BACKGROUND AND AIMS

Recurrent hepatitis C after liver transplantation (LT) is associated with rapid fibrosis progression. The aim of this study was to evaluate the cumulative risk for severe fibrosis and the factors influencing it.

PATIENTS AND METHODS

Two hundred and fifty LT patients were included 1 to 15years after LT. Recurrence of chronic hepatitis C on liver graft was classified according to Metavir score.

RESULTS

Kaplan-Meyer estimates for actuarial progression to severe fibrosis (Metavir>F3) showed a probability of 15.2% and 44.5% at 5 and 10years, respectively. Predictive factors for progression to severe fibrosis were: use of tacrolimus as main CNI, recipient age at time of biopsy<55, donor age ≥45, graft HCV re-infection<3months, biologically suspected graft re-infection and lack of response to antiviral treatment after LT. Multivariate analysis disclosed that only donor age ≥45 (hazard ratio 2.243, 95%CI 1.264-3.983, P=0.0058) and lack of response to antiviral treatment (hazard ratio 2.816, 95%CI 1.227-6.464, P=0.0146) were associated to severe fibrosis.

CONCLUSIONS

Our study confirms that donor age ≥45 and lack of response to antiviral treatment after LT are major predictive factors of progression of HCV recurrence on liver graft.

Directly acting antivirals (DAAs) for the treatment of chronic hepatitis C virus infection in liver transplant patients: "a flood of opportunity"

Chronic hepatitis C virus (HCV) is the leading cause of liver transplantation (LT) in adults. However, infection of the allograft is universal and associated with reduced graft and patient survival. Although successful eradication improves posttransplant outcome, current antiviral therapies have poor efficacy and tolerability. Direct acting antiviral agents (DAAs) provide new opportunities for treatment of HCV recurrence. The addition of a first-generation NS3/4A protease inhibitor (PI) has increased the efficacy of pegylated interferon and ribavirin in patients with chronic HCV genotype 1 infection. Preliminary efficacy results from open-labeled studies of PI-based triple therapy in LT recipients are encouraging. However, the tolerability of triple therapy is reduced following LT, because of increased anemia and drug-drug interactions. The use of PI-based triple therapy in LT recipients seems best suited to larger centers, experienced with management of PI toxicity. Fortunately, other classes of DAAs targeting different steps of HCV replication are in clinical trials, including nucleotide polymerase (NUC-NS5B) inhibitors, nonnucleotide polymerase (non-NUC-NS5B) inhibitors and NS5A inhibitors. Several dual and triple DAA regimens are in clinical development. Phase II studies conducted in patients before and after LT suggest that these regimens will dramatically reduce the impact of recurrent HCV. There is a tide in the affairs of men. Which, taken at the flood, leads on to fortune (Shakespeare: J Caesar Act 4, scene 3).

Challenges of recurrent hepatitis C in the liver transplant patient

Cirrhosis secondary to hepatitis C virus (HCV) is a very common indication for liver transplant. Unfortunately recurrence of HCV is almost universal in patients who are viremic at the time of transplant. The progression of fibrosis has been shown to be more rapid in the post-transplant patients than in the transplant naïve, hence treatment of recurrent HCV needs to be considered for all patients with documented recurrent HCV. Management of recurrent HCV is a challenging situation both for patients and physicians due to multiple reasons as discussed in this review. The standard HCV treatment with pegylated interferon and Ribavarin can be considered in these patients but it leads to a lower rate of sustained virologic clearance than in the non-transplanted population. Some of the main challenges associated with treating recurrent HCV in post-transplant patients include the presence of cytopenias; need to monitor drug-drug interactions and the increased incidence of renal compromise. In spite of these obstacles all patients with recurrent HCV should be considered for treatment since it is associated with improvement in survival and a delay in fibrosis progression. With the arrival of direct acting antiviral drugs there is renewed hope for better outcomes in the treatment of post-transplant HCV recurrence. This review evaluates current literature on this topic and identifies challenges associated with the management of post-transplant HCV recurrence.

REFINE: a randomized trial comparing cyclosporine A and tacrolimus on fibrosis after liver transplantation for hepatitis C

REFINE was a 12-month, prospective, open-label study in 356 patients receiving de novo liver transplantation for hepatitis C virus (HCV) cirrhosis, randomized to cyclosporine A (CsA) or tacrolimus with (i) no steroids, IL-2 receptor antibody induction and mycophenolic acid, or (ii) slow steroid tapering. The primary analysis population based on availability of liver biopsies comprised 165 patients (88 CsA, 77 tacrolimus). There was no difference in the primary endpoint, fibrosis stage ≥2 at 12 months, which occurred in 63/88 CsA-treated patients (71.6%) and 52/77 tacrolimus-treated patients (67.5%) (odds ratio [OR] 1.11; 95% CI 0.56, 2.21; p = 0.759). Similarly, no significant between-group difference occurred at month 24 (OR 1.15; 95% CI 0.47, 2.80; p = 0.767). Among steroid-free patients, fibrosis score ≥2 was significantly less frequent with CsA versus tacrolimus at month 12 (7/37 [18.9%] vs. 16/38 [42.1%]; p = 0.029). HCV viral load was similar in both the tacrolimus- and CsA-treated cohorts. Mean blood glucose was significantly higher with tacrolimus from day 15 onward. Biopsy-proven acute rejection, graft loss and death were similar. These results showed no differences in posttransplant HCV-induced liver fibrosis between patients treated with CsA or tacrolimus in steroid-containing regimens, whereas CsA in steroid-free protocols was associated with reduced severity of fibrosis progression at 1 year posttransplant.

Strategies to reduce hepatitis C virus recurrence after liver transplantation

Hepatitis C virus (HCV) is a major health problem that leads to chronic hepatitis, cirrhosis and hepatocellular carcinoma, being the most frequent indication for liver transplantation in several countries. Unfortunately, HCV re-infects the liver graft almost invariably following reperfusion, with an accelerated history of recurrence, leading to 10%-30% of patients progressing to cirrhosis within 5 years of transplantation. In this sense, some groups have even advocated for not re-transplanting this patients, as lower patient and graft outcomes have been reported. However, the management of HCV recurrence is being optimized and several strategies to reduce post-transplant recurrence could improve outcomes, decrease the rate of re-transplantation and optimize the use of available grafts. Three moments may be the focus of potential actions in order to decrease the impact of viral recurrence: the pre-transplant moment, the transplant environment and the post-transplant management. In the pre-transplant setting, it is not well established if reducing the pre transplant viral load affects the risk for HCV progression after transplant. Obviously, antiviral treatment can render the patient HCV RNA negative post transplant but the long-term benefit has not yet been fully established to justify the cost and clinical risk. In the transplant moment, factors as donor age, cold ischemia time, graft steatosis and ischemia/reperfusion injury may lead to a higher and more aggressive viral recurrence. After the transplant, discussion about immunosuppression and the moment to start the treatment (prophylactic, pre-emptive or once-confirmed) together with new antiviral drugs are of interest. This review aims to help clinicians have a global overview of post-transplant HCV recurrence and strategies to reduce its impact on our patients.

Management of recurrent hepatitis C in orthotopic liver transplant recipients

End-stage liver disease and hepatocellular carcinoma from chronic hepatitis C are the most common indications for orthotopic liver transplantation and the incidence of both are projected to increase over the next decade. Recurrent hepatitis C virus infection of the allograft is associated with an accelerated progression to cirrhosis, graft loss, and death. This article presents an overview of the natural history of hepatitis C virus recurrence in liver transplant recipients and guidance on optimal management strategies.

Review article: the treatment of genotype 1 chronic hepatitis C virus infection in liver transplant candidates and recipients

BACKGROUND

Recently, the therapeutic landscape with regard to anti-HCV therapy has changed dramatically. The new directly acting anti-virals (DAAs) have demonstrated improved sustained virological response (SVR) compared with pegylated-interferon and ribavirin.

AIM

To examine and present the latest data with regard to anti-viral therapy in genotype 1 HCV-positive transplant candidates and recipients.

METHODS

An electronic search using Medline was performed. Search terms included 'HCV, DAA and protease inhibitor' in combination with 'treatment pre-transplantation' and 'treatment post-transplantation'.

RESULTS

Patients with advanced fibrosis and cirrhosis have inferior SVR rates compared with patients with minimal fibrosis. A low accelerating dose regimen (LADR) of pegylated interferon and ribavirin (PR) appears to be a safe therapeutic option. Side effects also appear to be more pronounced in patients with advanced disease. Data from the large registration studies with triple therapy (boceprevir or telaprevir plus PR) demonstrated improved SVR rates even in patients with advanced disease, although virological relapse rates were highest amongst these patients. In transplant recipients, initial data are being reported on the use of triple therapy, and although no SVR data are available, promising results are accruing. The drug-drug interactions appear to be manageable. Side effects in particular anaemia appear to be markedly increased in the posttransplant setting.

CONCLUSIONS

The use of the new DAAs in patients with advanced fibrosis/cirrhosis pretransplant and posttransplant appears possible, with manageable side effects and drug-drug interactions, and improved early virological response rates. We recommend that these patients are managed in centres with the appropriate expertise.

Recurrent hepatitis C virus infection post liver transplantation: impact of choice of calcineurin inhibitor

Recurrence of hepatitis C virus infection following liver transplantation (LT) for hepatitis C is universal. After LT, hepatitis C is associated with accelerated fibrosis progression and reduced graft and patient survival. Furthermore, responses to antiviral therapy in patients with recurrent hepatitis C virus post-transplant are consistently sub-optimal. Calcineurin inhibitors (CNIs) like cyclosporine A (CsA) and tacrolimus continue to dominate immunosuppressive regimens in this population; however, there is still uncertainty as to whether either offers an advantage in terms of patient outcomes. Although tacrolimus demonstrates improved efficacy in the general LT population, differences have begun to emerge between these agents regarding diabetogenic potential, antiviral activity, and fibrosis progression in patients with hepatitis C. This review critically evaluates the existing literature, providing an overview of the reported differences, concluding that despite conflicting evidence, a potential benefit of CsA in patients with hepatitis C is supported by the data and warrants further investigation. Future studies examining the role of CNIs in hepatitis C virus-positive LT recipients are required to accurately examine the effects of CNIs on outcomes such as fibrosis progression, survival, and effects on response to antiviral therapy, to provide robust information that allows clinicians to make an informed choice concerning which CNI is best for their patients.

Immunomodulating options for liver transplant patients

Much has changed since the early years of liver transplantation. Improvements in post-transplant survival are largely due to more selective and less toxic immunosuppression regimens and advances in operative and perioperative care. This has allowed liver transplantation to become an extremely successful treatment option for patients with endstage liver disease. Beginning with cyclosporine, a cyclic endecapeptide of fungal origin and the first of the calcineurin inhibitors to find widespread use, immunosuppressive regimens have evolved to include additional calcineurin inhibitors, steroids, mTOR inhibitors, antimetabolites and antibodies, mostly targeting T-cell activation. This review will present currently available immunosuppressive agents used in the perioperative period of liver transplantation, as well as maintenance treatments, tailoring therapeutic strategies for specific populations, and advances in immune monitoring and tolerance.

Efficacy of antiviral therapy for hepatitis C after liver transplantation with cyclosporine and tacrolimus: a systematic review and meta-analysis

Cyclosporine A (CSA), but not tacrolimus (TAC), inhibits hepatitis C virus (HCV) replication in vitro. Clinical reports on the efficacy of interferon-α (IFNα)-based antiviral therapy (AVT) for recurrent HCV after liver transplantation (LT) with CSA and TAC are conflicting. Our aim was to assess whether AVT for recurrent HCV after LT is more effective with CSA or TAC. We performed an electronic database search (1995-2012) and a manual abstract search (2005-2012). The a priori defined eligibility criteria included the use of AVT for recurrent HCV with IFN (standard or pegylated) and ribavirin and the reporting of sustained virological response (SVR) rates with CSA and TAC (the primary outcome). Two authors identified and extracted data independently. Dichotomous data were expressed as relative risks (RRs) and 95% confidence intervals (CIs) with a random effects model. In all, 5058 references were retrieved, and 1 randomized controlled trial (RCT) and 17 observational studies (13 full-text articles) met the eligibility criteria; the meta-analysis was based on the latter studies. The pooled SVR rates were 42% (395/945) with CSA and 35% (471/1364) with TAC (RR = 1.18, 95% CI = 1.00-1.39, P = 0.05). Although the pooled data contained significant heterogeneity (I(2) = 45%, P = 0.02), the SVR rates in the RCT were comparable (39% with CSA and 35% with TAC). Limiting the analysis to the 7 studies reporting on 40 or more patients in each group (with 1634 patients in all) favored CSA (RR = 1.23, 95% CI = 1.09-1.38, P < 0.001), and heterogeneity disappeared (I(2) = 0%, P = 0.62). In conclusion, IFN-based AVT for recurrent HCV after LT seems marginally more effective with CSA versus TAC; the study heterogeneity, however, limits firm conclusions.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.

Peginterferon-α-2b and ribavirin for hepatitis C recurrence postorthotopic liver transplantation

GOALS

To evaluate the safety and efficacy of peginterferon-α-2b plus ribavirin in patients with recurrent hepatitis C after orthotopic liver transplant.

BACKGROUND

Reinfection of liver allografts in hepatitis C virus -infected transplant recipients begins immediately after transplantation. Treatment of these patients is challenging because of poor tolerability.

STUDY

A multicenter, open-label study enrolling patients with persistent viremia after primary orthotopic liver transplant for cirrhosis related to hepatitis C virus infection. Patients received peginterferon-α-2b (1.5 µg/kg/wk) plus ribavirin (400 to 1200 mg/d administered using a dose-escalating regimen and according to body weight) for 48 weeks. The primary endpoint was sustained virologic response (SVR).

RESULTS

In total, 125 patients started treatment and 58.4% completed 48 weeks. SVR rate was 28.8% (G1, 23.8%; G2/3, 55.0%), end-of-treatment response rate was 40.8%, and relapse rate was 18.2%. SVR was 55% among patients who completed treatment. Genotype 2/3 infection, male sex, baseline hemoglobin>14 g/dL, 80:80:80 compliance, rapid virologic response (RVR), and complete early virologic response (cEVR) were predictors of SVR. SVR was higher among patients with RVR compared with those without RVR (83.3% vs. 25.7%; P=0.0098), and among patients with cEVR compared with those without EVR (66.7% vs. 1.8%; P<0.0001). Thirty-eight patients discontinued because of an adverse event and 69 required dose reduction or interruption. Anemia (74%) and neutropenia (30%) were common, and rejection was low (3.2%).

CONCLUSIONS

SVR was low in this study. Anemia was a particular challenge in achieving maximal ribavirin therapeutic exposure and may account in part for the lower SVR.

The adverse pharmacology of calcineurin inhibitors and their impact on hepatitis C recurrence after liver transplantation: implications for clinical practice

Calcineurin inhibitors are widely used as maintenance immunosuppressants in solid-organ transplantation to minimize the risk of allograft rejection. Although the use of these agents has transformed the outcomes for patient and graft survival, this has come at a cost, notably the well-known adverse events of nephrotoxicity and metabolic abnormalities, to name a few. Over the last decade, tremendous interest has also focused on the impact of these medications on the replication of hepatitis C virus (HCV), with cyclosporine in particular having a negative effect on viral replication in vitro. Although small retrospective studies suggested that there may be a beneficial effect with cyclosporine on the progression of recurrent HCV and response to interferon, these findings have not been validated in several well-designed randomized controlled trial studies. The authors will review the pharmacology and pharmacokinetics of these well-known drugs and discuss the impact of these medications on the natural history of HCV recurrence after liver transplantation.

HCV in liver transplantation

HCV-related cirrhosis represents the leading indication for liver transplantation in the Western countries. HCV reinfection after liver transplantation occurs in virtually all patients transplanted for HCV-related liver disease Histological evidence of chronic HCV infection develops in 50 to 90 % of patients by 12 months after liver transplantation, and cirrhosis occurs in about 20 % of patients within 5 years after transplant. Several studies have evaluated host, viral, and transplant-related factors that might be associated with the severity of HCV recurrence. Among host factors, immunosuppression is one of the major factors that accounts for accelerated HCV recurrence and it has been an area of extensive research and controversy. Donor age, steatosis, and immunogenetic factors are also relevant in determining the outcome in patients transplanted for HCV-related cirrhosis. A major step to prevent complications of HCV recurrence related to the rapid fibrosis is the posttransplant antiviral treatment. Two strategies have been tried: pre-emptive or other strategies as soon as possible after liver transplantation or elective therapy once there is histological evidence of recurrent hepatitis C. Retransplantation due to graft failure from recurrent hepatitis C is rarely an option in the era of organ shortage as it is associated with poor outcome, but many case needs to be considered early in the evolution of disease. New antivirals may change the outcome dramatically of patients transplanted for HCV cirrhosis.

Cyclosporin A inhibits the influenza virus replication through cyclophilin A-dependent and -independent pathways

The immunosuppressive drug cyclosporin A (CsA) has inhibitory effects on the replication of several viruses. The antiviral effects are through targeting the interaction between viral proteins and host factor cyclophilin A (CypA). CypA has been identified to interact with influenza A virus M1 protein and impair the early stage of the viral life cycle. In order to identify the effect of CsA on influenza virus replication, a CypA-depleted 293T cell line, which was named as 293T/CypA−, was constructed. The cytopathic effect (CPE) assay and the growth curve results indicated that CsA specifically suppressed the influenza A virus replication in a dose-dependent manner. CsA treatment had no effect on the viral genome replication and transcription but selectively suppressed the viral proteins expression. Further studies indicated that CsA could impair the nuclear export of viral mRNA in the absence of CypA. In addition, the antiviral activity of CsA was independent of calcineurin signaling. Finally, CsA could enhance the binding between CypA and M1. The above results suggested that CsA inhibited the replication of influenza A virus through CypA-dependent and -independent pathways.

Virus-drug interactions--molecular insight into immunosuppression and HCV

Liver transplantation is an effective treatment for end-stage liver disease that is attributable to chronic HCV infection. However, long-term outcomes are compromised by universal virological recurrence in the graft. Reinfection that occurs after transplantation has increased resistance to current interferon-based antiviral therapy and often leads to accelerated development of cirrhosis. Important risk factors for severe HCV recurrence are linked to immunosuppression. Owing to the lack of good randomized, controlled trials, the optimal choice of immunosuppressants is still debated. By contrast, much progress has been made in the understanding of HCV biology and the antiviral action of interferons. These new insights have greatly expanded our knowledge of the molecular interplay between HCV and immunosuppressive drugs. In this article, we explore the effect of different immunosuppressants on the complex cellular events involved in HCV infection and interferon signalling. Potential implications for clinical practice and future drug development are discussed.

Immunosuppression and HCV recurrence after liver transplantation

HCV related liver disease is the most common indication for liver transplantation. Recurrence of HCV infection is universal and has a substantial impact on patient and graft survival. Immunosuppression is a major factor responsible for the accelerated recurrence and compressed natural history of recurrent HCV infection. Accumulating experience has provided data to support certain strategies for immunosuppressive regimens. From the available evidence, more severe recurrence results from repeated bolus corticosteroid therapy and anti-lymphocyte antibodies used to treat rejection. Low dose and slow tapering of steroids are better than high dose maintenance and/or rapid tapering. Recent meta-analyses favour steroid-free regimens but these are complicated to interpret as the absence of steroids may simply represent less immunopotency. There is no difference in HCV recurrence between tacrolimus and cyclosporine regimens, but tacrolimus increases graft and patient survival in HCV transplanted patients. There may be a beneficial effect of maintenance azathioprine given for 6 months or longer. There is no conclusive evidence for benefit of mycophenolate and interleukin-2 receptor blockers. Few data are available for mTOR inhibitors. Better evidence is needed to establish the optimal immunosuppressive regimen for HCV recipients and more randomized trials should be performed.

Hepatitis C virus treatment pre- and post-liver transplantation

Liver disease caused by the hepatitis C virus is the main indication for liver transplantation in Western countries. However, HCV re-infection post-transplantation is constant and recent data confirm that it significantly impairs patient and graft survival. Chronic HCV infection develops in 75-90% of patients, and 5-30% ultimately progress to cirrhosis within 5 years. Because of the impact of HCV recurrence on graft and patient survival, several treatment strategies have been evaluated. Antiviral therapy could be administered before transplantation to suppress viral replication and reduce the risk of recurrence. However, this approach is applicable in around 50% of patients and tolerance is poor, particularly in patients with decompensated cirrhosis. Pre-emptive therapy in the early post-transplant period is limited by the high rate of side effects. Frequently, antiviral therapy is initiated when HCV recurs to obtain viral eradication and/or reduce disease progression. Treatment of established graft lesions with Pegylated Interferon (PEG-IFN) and Ribavirin (RBV) combination therapy results in a sustained virological response (SVR) in around 30% of patients. The new classes of potent and direct antiviral agents (DAA) will certainly improve the results of pre- and post-transplant antiviral therapy. However, at the present time, no data are available on the use of these drugs in patients with decompensated cirrhosis or post-transplant hepatitis.

Optimization of the use of Calcineurin inhibitors in liver transplantation

Calcineurin inhibitors (CNIs), such as cyclosporin A and tacrolimus, are the cornerstone of maintenance immunosuppressive regimens in liver transplantation. CNIs prevent rejection by inhibition of calcineurin, via which lymphocyte proliferation and interleukin (IL)-2 production is prevented. Tacrolimus is now the first-choice immunosuppressant after liver transplantation, since it is associated with fewer episodes of rejection than cyclosporin A. In this review we will discuss interindividual differences, which influence tacrolimus metabolism. Because of these factors and the narrow therapeutic index of tacrolimus, monitoring of drug trough levels is necessary. Furthermore, we will discuss studies concerning conversion from the tacrolimus twice daily to tacrolimus once daily formulation in stable LT patients. Due to adverse effects of CNIs, such as chronic renal failure, hypertension, de novo malignancy and new-onset diabetes mellitus, CNI minimization strategies have been developed, which will be discussed too.

Liver transplantation and hepatitis C

Hepatitis-C-virus- (HCV-) related end-stage cirrhosis is the primary indication for liver transplantation in many countries. Unfortunately, however, HCV is not eliminated by transplantation and graft reinfection is universal, resulting in fibrosis, cirrhosis, and finally graft decompensation. The use of poor quality organs, particularly from older donors, has a highly negative impact on the severity of recurrence and patient/graft survival. Although immunosuppressive regimens have a considerable impact on the outcome, the optimal regimen after liver transplantation for HCV-infected patients remains unclear. Disease progression monitoring with protocol biopsy and new noninvasive methods is essential for predicting patient/graft outcome and starting antiviral treatment with the appropriate timing. Antiviral treatment with pegylated interferon and ribavirin is currently considered the most promising regimen with a sustained viral response rate of around 30% to 35%, although the survival benefit of this regimen remains to be investigated. Living-donor liver transplantation is now widely accepted as an established treatment for HCV cirrhosis and the results are equivalent to those of deceased donor liver transplantation.

Impact of calcineurin inhibitors with or without interferon on hepatitis C virus titers in a chimeric mouse model of hepatitis C virus infection

Cyclosporine A (CSA) has potent effects against hepatitis C virus (HCV) in vitro, but its clinical efficacy after liver transplantation (LT) is uncertain. We evaluated the impact of CSA and tacrolimus (TAC) with or without concomitant interferon (IFN) therapy on serum HCV titers in a chimeric mouse model of HCV infection. Six groups of HCV-infected mice received only the vehicle, IFN, CSA, CSA and IFN, TAC, or TAC and IFN for 4 weeks. The quantitative HCV polymerase chain reaction levels were determined after 1, 2, and 4 weeks of drug administration. There were no significant differences in the HCV titers after 4 weeks of treatment between the non-IFN-treated groups (log HCV titers: 3.5 ± 0.3 for the vehicle group, 4.4 ± 0.6 for the CSA group, and 4.3 ± 0.4 for the TAC group, P = 0.3). Although IFN had a consistent effect of reducing HCV titers across the groups, there was no significant impact of CSA on HCV levels when it was used alone or in combination with IFN at any time point. The 4-week HCV titers were as follows: 3.2 ± 0.3 for the IFN group, 4.7 ± 0.4 for the CSA/IFN group, and 4.0 ± 0.5 for the TAC/IFN group (P = 0.07). The CSA/IFN and TAC/IFN groups did not differ significantly (P = 0.6). Six of the 7 animals in the IFN group (85.7%) had an HCV titer decline ≥ 1 log, whereas in the test groups (CSA/IFN and TAC/IFN), 6 of 9 animals (66.7%) achieved a 1-log decline in the HCV titer (P = 1). Using this animal model, we could find no evidence supporting the routine use of CSA after LT in HCV-infected patients.

m-TOR inhibitors: what role in liver transplantation?

The development of calcineurin inhibitors (CNIs) led to marked improvements in patient and graft survival after liver transplantation (LTx). We have been left, however, with a dependence on immunosuppressive agents with nephrotoxicity, neurotoxicity, adverse impacts on cardiac risk profile, and risk for malignancy. These challenges need to be met against a dominance of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC) as indications for liver transplant. Unmet needs for immunosuppression (IS) in LTx include: (1) Effective drugs that avoid CNIs toxicities. (2) Agents without adverse impact on HCV recurrence. (3) Compounds that minimize risk of HCC recurrence. New immunosuppressives will need to address the above needs while supporting patient and graft survival equivalent to those achievable with CNIs, ideally without important new toxicities. Two new classes of agents are currently in advanced clinical development: belatacept, and the mammalian target of rapamycin inhibitors (m-TORi). This manuscript will review evidence for a role for m-TORi in LTx in a range of clinical scenarios including patients with CNI nephrotoxicity or neurotoxicity, patients at risk of (or with) HCV recurrence, and patients at risk of HCC recurrence.

Hot-topic debate on hepatitis C virus: the type of immunosuppression matters

1. The treatment of rejection is an important factor associated with the severe recurrence of hepatitis C virus (HCV) after liver transplantation. 2. The effects of calcineurin inhibitors, corticosteroids, and mycophenolate mofetil on HCV recurrence are equivocal. 3. Cyclosporine is associated with a higher sustained virological response in patients treated for HCV. 4. Because insulin resistance and diabetes are associated with fibrosis in HCV-infected liver transplant recipients, the use of immunosuppressive agents without this side effect may slow the posttransplant disease progression.

Present state of immunosuppressive therapy in liver transplant recipients

1. Our increasing understanding of the signaling pathways and cellular interactions in transplant immunobiology has facilitated targeted strategies using novel immunosuppressive agents. 2. The pattern of immunosuppressive drug use in the United States continues to change, and the changes include the use of antibody induction therapy and the agents used in maintenance therapy. 3. The driving forces behind the development of new immunosuppressive regimens are the long-term complications of current immunosuppressive regimens (particularly renal dysfunction and metabolic disturbances).

Cyclosporine a-based immunosuppression reduces relapse rate after antiviral therapy in transplanted patients with hepatitis C virus infection: a large multicenter cohort study

BACKGROUND

The influence of immunosuppression on the response to antiviral treatment in recurrent hepatitis C is still under debate. The purpose of this study was to identify those factors that might predict sustained viral response and relapse.

METHODS

The ReViS-TC, a multicenter cohort study conducted in 14 Spanish liver centers, included data from liver transplant recipients from January 2000 to December 2006 who had recurrent hepatitis C virus and who had undergone antiviral treatment with pegylated interferon plus ribavirin. Sustained virological response (SVR) and viral relapse were evaluated. A multivariate logistic regression model was used to investigate host, donor, and therapeutic factors associated with SVR and relapse.

RESULTS

The analysis included 410 patients, 30% treated with cyclosporine A (CsA) and 70% with tacrolimus. SVR was achieved in 48% of patients with CsA and in 37% with tacrolimus (P=0.037), with a relapse rate of 18% and 36%, respectively (P=0.008). In the multivariate model, the administration of CsA (odds ratio [OR] 0.37, P=0.021) in conjunction with a longer antiviral treatment duration (OR 0.86, P=0.024) correlated with lower relapse rate, whereas the older age of the donor (OR 1.03, P=0.006) and the presence of genotype 1 (OR 3.45, P=0.032) were associated with a higher probability of relapse.

CONCLUSIONS

Our results suggest that the use of CsA-based immunosuppression regimens and longer treatment duration may protect patients against viral relapse after a positive response to pegylated interferon plus ribavirin therapy. These data need to be further confirmed in clinical trials.

The influence of immunosuppressive agents on BK virus risk following kidney transplantation, and implications for choice of regimen

The increasing incidence of BK-associated nephropathy following kidney transplantation has prompted an examination of strategies for risk reduction and management through immunosuppression manipulation. Evidence from retrospective and prospective studies suggests that BK viruria and viremia, and the need for BK virus treatment, are higher with tacrolimus than cyclosporine. Combined therapy with tacrolimus and mycophenolic acid may be associated with a particularly higher risk of BK infection, but data are conflicting as to whether mycophenolic acid per se is an independent risk factor. The incidence of BK-related events may be reduced in patients receiving mTOR inhibitors (everolimus or sirolimus) with cyclosporine vs a calcineurin inhibitor with mycophenolic acid. De novo immunosuppression regimens that avoid rabbit antithymocyte globulin and tacrolimus, particularly tacrolimus with mycophenolic acid, may be advantageous, whereas low-exposure cyclosporine with an mTOR inhibitor appears a favorable option. Routine screening for BK infection during the first 2 years posttransplant is recommended to allow preemptive modification of the immunosuppressive regimen. In patients at high risk of BK virus infection, appropriate de novo immunosuppression or very early conversion to an mTOR inhibitor to facilitate reduction or discontinuation of calcineurin inhibitors or antimetabolites should be considered. Extensive further research into optimal avoidance, screening, and treatment strategies is required.

Potent antifibrotic activity of mTOR inhibitors sirolimus and everolimus but not of cyclosporine A and tacrolimus in experimental liver fibrosis

BACKGROUND & AIMS

Recurrence of chronic hepatitis C and progressive fibrosis in liver transplants is frequent and impairs both graft and patient survival. Whether or not the choice of immunosuppression affects progression of fibrosis remains unclear. The aim of the present study was to compare the potential of the commonly used immunosuppressants to halt experimental liver fibrosis progression.

METHODS

To induce liver fibrosis, rats underwent bile duct ligation and treatment with sirolimus (2mg/kg), everolimus (3mg/kg), tacrolimus (1mg/kg), and cyclosporin A (10mg/kg) daily for 5 weeks. Fibrosis, inflammation, and portal pressure were evaluated by histology, hydroxyproline levels, morphometry, hemodynamics, and hepatic gene expression.

RESULTS

Sirolimus and everolimus decreased fibrosis up to 70%, improved portal pressure, reduced ascites, and showed potent down-regulation of pro-fibrogenic genes, paralleled by a strong increase in matrix degradation (collagenase) activity; in contrast, tacrolimus and cyclosporine A had no or even aggravating effects on liver fibrosis in rats.

CONCLUSIONS

mTOR inhibition by sirolimus and everolimus in experimental liver fibrosis associates with significantly less fibrosis progression and portal hypertension than treatment with calcineurin inhibitors tacrolimus and cyclosporine A. These data suggest that the selection of the immunosuppressant could impact the recurrence of fibrosis in liver allografts.

BK Virus in Kidney Transplant Recipients: The Influence of Immunosuppression

The incidence of BK virus infection in kidney transplant recipients has increased over recent decades, coincident with the use of more potent immunosuppression. More importantly, posttransplant BK virus replication has emerged as an important cause of graft damage and subsequent graft loss. Immunosuppression has been accepted as a major risk for BK virus replication. However, the specific contribution of individual immunosuppressive medications to this risk has not been well established. The purpose of this paper is to provide an overview of the recent literature on the influence of the various immunosuppressant drugs and drug combinations on posttransplant BK virus replication. Evidence supporting the various immunosuppression reduction strategies utilised in the management of BK virus will also be briefly discussed.

Evolving concepts in the selection of immunosuppression regimen for liver transplant recipients

The introduction of calcineurin inhibitor (CNI) based immunosuppression has revolutionized the field of liver transplantation by dramatically reducing the incidence of acute cellular rejection and prolonging patient and allograft survival. However, the introduction of CNIs has also come at the price of increased patient morbidity, particularly with regard to the well-known nephrotoxic effects of the medications. In an effort to minimize the adverse effects, immunosuppression regimen have evolved to include the use of various induction agents and purine synthesis inhibitors to limit the dose of CNI necessary to achieve low acute cellular rejection rates. Careful assessments of risks and benefits are needed as these newer agents have their own side effect profiles. In addition, the impact of newer immunosuppression regimen on hepatitis C (HCV) recurrence has not been completely elucidated. This review will provide an overview of the most common immunosuppression regimen used in liver transplantation and discuss their impact on acute cellular rejection, patient and allograft survival, and HCV recurrence.