Early recurrence of hepatitis C virus infection after liver transplantation

Experimental transmission of equine hepacivirus in horses as a model for hepatitis C virus

Equine hepacivirus (EHCV; nonprimate hepacivirus) is a hepatotropic member of the Flaviviridae family that infects horses. Although EHCV is the closest known relative to hepatitis C virus (HCV), its complete replication kinetics in vivo have not been described, and direct evidence that it causes hepatitis has been lacking. In this study, we detected EHCV in 2 horses that developed post-transfusion hepatitis. Plasma and serum from these horses were used to experimentally transmit EHCV to 4 young adult Arabian horses, two 1-month-old foals (1 Arabian and 1 Arabian-pony cross), and 2 foals (1 Arabian and 1 Arabian-pony cross) with severe combined immunodeficiency (SCID). Our results demonstrated that EHCV had infection kinetics similar to HCV and that infection was associated with acute and chronic liver disease as measured by elevations of liver-specific enzymes and/or by histopathology. Although most of these animals were coinfected with equine pegivirus (EPgV), also a flavivirus, EPgV viral loads were much lower and often undetectable in both liver and blood. Three additional young adult Arabian-pony crosses and 1 SCID foal were then inoculated with plasma containing only EHCV, and evidence of mild hepatocellular damage was observed. The different levels of liver-specific enzyme elevation, hepatic inflammation, and duration of viremia observed during EHCV infection suggested that the magnitude and course of liver disease was mediated by the virus inoculum and/or by host factors, including breed, age, and adaptive immune status.

CONCLUSION

This work documents the complete infection kinetics and liver pathology associated with acute and chronic EHCV infection in horses and further justifies it as a large animal model for HCV.

Recurrent diseases following liver transplantation: current concepts

PURPOSE OF REVIEW

Liver transplantation is the treatment of choice for patients with chronic end-stage liver disease. The posttransplant setting is complex, and an improved long-term graft and patient survival adds to the complexity. There are often multiple causes of graft dysfunction and the associated morbidity and disorder are varied. This review focuses on the current concepts of several recurrent diseases, emphasizing the interpretation of the posttransplant liver biopsies in long-term survivors as challenging and clinically more relevant then ever. It confirms the importance and the necessity of clinico-pathologic correlation in the posttransplant setting.

RECENT FINDINGS

The long-term graft and patient survival following liver transplantation has improved significantly over the past decade. The spectrum of histopathologic patterns seen in liver biopsies and our understanding of them have evolved and expanded considerably, so much so, that both pathologists and clinicians alike now recognize new and emerging disease patterns not previously encountered in the nontransplant setting.

SUMMARY

Typical histopathologic features are usually easily identified and interpreted in liver biopsies. There are, however, a number of atypical histopathologic patterns, especially in the setting of recurrent diseases, often modified by immunosuppression, or altered by other immune-mediated processes, autoimmunity, or hepatotoxicity. Several conditions and entities, especially in the late posttransplant setting, including atypical allograft rejection, idiopathic posttransplant hepatitis, the spectrum of changes seen in recurrent hepatitis C, nodular regenerative hyperplasia, and de-novo disease occurrence, to name a few, have all been recognized in the past several years.

A Randomized Multicenter Study Comparing a Tacrolimus-Based Protocol with and without Steroids in HCV-Positive Liver Allograft Recipients

Allograft reinfection with hepatitis C virus (HCV) occurs universally in liver transplant recipients. Corticosteroids can contribute to HCV recurrence. This randomized study evaluated HCV recurrence in HCV-positive liver allograft recipients using steroid-free immunosuppression. All patients received tacrolimus (TAC) at an initial dose of 0.10–0.15 mg/kg. The steroid-free arm (TAC/daclizumab (TAC/DAC, n = 67)) received daclizumab induction, and the steroid arm (TAC/steroid (TAC/STR, n = 68)) received a steroid bolus (≤ 500mg) followed by 15–20 mg/day with discontinuation after month 3. Median HCV viral load at month 12, the primary endpoint, was similar at 5.46 (0.95–6.54) IU/mL with TAC/DAC and 5.91 (0.95–6.89) IU/mL with TAC/STR. Small numerical differences in the estimated rate of freedom from HCV recurrence (19.1 versus 13.8%) and freedom from biopsy proven rejection (78.4 versus 66.1%) were observed between TAC/DAC and TAC/STR. Patient survival estimates were significantly lower with TAC/DAC than with TAC/STR (83.1 versus 95.5%; 95% CI, −0.227 to −0.019%), and graft survival was numerically lower (80.1 versus 91.1%, P = NS). Completion rates (45 versus 82%) indicated poorer tolerability with TAC/DAC than with TAC/STR. Steroid-free immunosuppression had no real impact on HCV viral load. HCV recurrence was higher with TAC/STR. Results are inconclusive due to the unexpected lower completion rates in the TAC/DAC arm.

Hepatitis C recurrence after liver transplantation: has the human leukocyte antigen mismatching at individual loci a role?

BACKGROUND AND AIM

The objective of this 11-year cohort retrospective study conducted in adult patients with chronic hepatitis C virus (HCV) who underwent liver transplantation (LT) was to identify whether human leukocyte antigen (HLA) mismatching is associated with the recurrence of HCV and with the time to recurrence of HCV.

METHODS

Among the 181 patients (74% men; mean age: 54 years, range 25-71) who underwent a LT between 1995 and 2006 in the study center, 163 had relevant data in their medical chart documenting HCV recurrence, and 107 (65.64%) reported a histological evidence of HCV recurrence.

RESULTS

Survival was 78% at 5 years. There was no significant relationship between the total score of HLA-mismatches and the recurrence of HCV. Similarly, there was no significant relationship between the total score of HLA mismatches and the time to recurrence of HCV. For the analyses at each individual locus, a significant relationship between the individual scores of HLA-mismatches and the recurrence of HCV were observed. Out of the 40 patients who experienced a rejection, the rate of recurrence was not different according to the severity of the rejection (75% mild, 64% moderate and 64% for severe rejection).

CONCLUSIONS

In conclusion, this large study did not demonstrate any relationship between the total score of HLA mismatches and HCV-recurrence. Contrarily a significant relationship between the individual scores of HLA mismatches (HLA-A3, HLA-B35, HLA-DR3, HLA-DR7, HLA-DQ2, HLA-DQ2-0) and the recurrence of HCV were observed.

Current views on rejection pathology in liver transplantation

Histological assessments continue to play an important role in the diagnosis and management of liver allograft rejection. The changes occurring in acute and chronic rejection are well recognized and liver biopsy remains the 'gold standard' for diagnosing these two conditions. Recent interest has focused on the diagnosis of late cellular rejection, which may have different histological appearances to early acute rejection and instead has features that overlap with so-called 'de novo autoimmune hepatitis' and 'idiopathic post-transplant chronic hepatitis'. There is increasing evidence to suggest that 'central perivenulitis' may be an important manifestation of late rejection, although other causes of centrilobular necro-inflammation need to be considered in the differential diagnosis. There are also important areas of overlap between rejection and recurrent hepatitis C infection and the distinction between these two conditions continues to be a problem in the assessment of liver allograft biopsies. Studies using immunohistochemical staining for C4d as a marker for antibody-mediated damage have found evidence of C4d deposition in liver allograft rejection, but the functional significance of these observations is currently uncertain. This review will focus on these difficult and controversial areas in the pathology of rejection, documenting what is currently known and identifying areas where further clarification is required.

Adoptive immunotherapy with liver allograft-derived lymphocytes induces anti-HCV activity after liver transplantation in humans and humanized mice

After liver transplantation in HCV-infected patients, the virus load inevitably exceeds pre-transplantation levels. This phenomenon reflects suppression of the host-effector immune responses that control HCV replication by the immunosuppressive drugs used to prevent rejection of the transplanted liver. Here, we describe an adoptive immunotherapy approach, using lymphocytes extracted from liver allograft perfusate (termed herein liver allograft-derived lymphocytes), which includes an abundance of NK/NKT cells that mounted an anti-HCV response in HCV-infected liver transplantation recipients, despite the immunosuppressive environment. This therapy involved intravenously injecting patients 3 days after liver transplantation with liver allograft-derived lymphocytes treated with IL-2 and the CD3-specific mAb OKT3. During the first month after liver transplantation, the HCV RNA titers in the sera of recipients who received immunotherapy were markedly lower than those in the sera of recipients who did not receive immunotherapy. We further explored these observations in human hepatocyte-chimeric mice, in which mouse hepatocytes were replaced by human hepatocytes. These mice unfailingly developed HCV infections after inoculation with HCV-infected human serum. However, injection of human liver-derived lymphocytes treated with IL-2/OKT3 completely prevented HCV infection. Furthermore, an in vitro study using genomic HCV replicon-containing hepatic cells revealed that IFN-gamma-secreting cells played a pivotal role in such anti-HCV responses. Thus, our study presents what we believe to be a novel paradigm for the inhibition of HCV replication in HCV-infected liver transplantation recipients.

Elevated CD4+/CD25+ T-cell frequency and function during hepatitis C virus recurrence after liver transplantation

BACKGROUND/AIM

Factors involved in hepatitis C virus (HCV) recurrence versus acute cellular rejection are not fully understood. The aim of the present study was to investigate whether patients with recurrence after liver transplantation (OLT) showed similar CD4(+)/CD25(+) cell frequency and function as those who became chronically infected.

PATIENTS AND METHODS

After written informed consent, we enrolled 20 patients (group A) who underwent OLT with HCV recurrence within 6 months. HCV-RNA and hypertransaminasemia were used to assess the reactivation of viral hepatitis. CD4(+)/CD25(+) T cells were enumerated using a flow cytometry assay, gated on CD3 cells, stained for FoxP3. After immunomagnetic sorting (Dynal, Oslo, NW), Treg suppressor activity was measured, as the ability to inhibit proliferation of autologous CD4(+)/CD25(-) T cells (anti-CD3/CD28 stimulation-1:2, 1:20 ratio). Eight patients with acute hepatitis C who evolved to a chronic infection after 6 months (group B) were used as positive controls, while 10 healthy individuals were negative controls (group C).

RESULTS

We did not observe any difference in CD4(+)/CD25(+) frequency or function among group A compared with group B (CD4(+)/CD25(+) = 14% +/- 2% versus CD4(+)/CD25(+) = 16% +/- 3%), although both groups were significantly increased with respect to group A (CD4(+)/CD25(+) = 6% +/- 3%; Mann-Whitney U test, P < .01).

CONCLUSION

Patients developing HCV recurrence after OLT have the same immunoregulatory network as patients with acute hepatitis C evolving to persistent infection, likely suggesting that CD4(+)/CD25(+) numbers may be a marker to predict recurrence of HCV after OLT.

Posttransplant plasma cell hepatitis (de novo autoimmune hepatitis) is a variant of rejection and may lead to a negative outcome in patients with hepatitis C virus

De novo autoimmune hepatitis has been described in both pediatric and adult liver transplantation (LT) recipients. Studies of small numbers of patients have proposed it to be an alloimmune hepatitis or form of chronic rejection. We have recently noted an increasing number of patients with post-LT recurrent hepatitis C virus (HCV) developing this, with an apparent negative impact on outcome and survival. We term this entity posttransplant plasma cell hepatitis (PCH). A search of our institution's pathology database was performed with the terms "plasma cell(s)," "lymphoplasmacytic infiltrate," and "liver allograft." A histological scoring system was devised to more reliably diagnose PCH in the setting of recurrent HCV. Thirty-eight patients were identified, and their clinical data were analyzed. Sixty percent had a negative outcome as defined by the development of cirrhosis, need for retransplantation, or death. Eighty-two percent had recent lowering of immunosuppression or subtherapeutic calcineurin inhibitor levels; 58% developed PCH within 2 years post-LT. Histologic resolution of PCH was associated with good outcome (P < 0.001). Patients not receiving treatment had a negative outcome (P = 0.007) as did patients receiving corticosteroids as therapy (P = 0.02). Persistence (P = 0.007) or recurrence of PCH was associated with negative outcome. In conclusion, PCH is a histologic variant of rejection. On liver biopsy, PCH can at times be difficult to diagnose, and the use of a standardized scoring system is recommended to differentiate it from other forms of allograft dysfunction. Treatment by optimization of immunosuppression without the use of corticosteroids appears effective. The development of PCH in the setting of recurrent HCV is a negative prognostic factor for patient outcome and allograft failure.

Liver transplantation: Yesterday, today and tomorrow

With the advances in technical skills, management of postoperative complications and improvements in immunosuppressive drugs, liver transplantation is the standard treatment for many patients with chronic liver disease. Today, shortage of donor organs seems to be the major limiting factor for the application of liver transplantation. This review focuses on five issues that are challenging to clinical practice of liver transplantation and relevant to gastroenterologists. These include living donor liver transplantation, recurrent viral hepatitis, non-heart-beating donors, hepatocellular carcinoma, and ABO incompatible liver transplantation. Living donor and non-heart beating donor transplantations were initiated as a solution to increase the donor organ pool and it is expected that there will be an increase in the number of these donors. Recurrent hepatitis C and hepatocellular carcinoma following liver transplantation are among major problems and ongoing research in these diseases may lead to better outcomes in these recipients.

Controversies in liver transplantation for hepatitis C

Hepatitis C is one of the most common indications for liver transplantation in the United States, accounting for approximately 40%-45% of all liver transplants. Unfortunately, recurrent disease is universal in patients who are viremic before transplantation. This can lead to cirrhosis in at least 25% of patients 5 years after liver transplantation, and recurrent hepatitis C is now emerging as an important but occasionally contentious indication for retransplantation. Several attempts have been undertaken to identify patients at high risk for severe recurrent disease who may benefit from treatment, but unfortunately antiviral therapy frequently is ineffective and often is associated with numerous side effects. Although we have made significant strides in understanding the natural history of this disease in nontransplant patients, this does not hold true for the transplant population in which several uncertainties covering virtually the entire spectrum of liver transplantation persist. Despite these concerns, on a more practical level, it is usually only in the postoperative setting that clinicians truly can assess the impact of their interventions on the natural history of recurrent hepatitis C, for example, by adjusting immunosuppression or prescribing antiviral therapy. Preoperative and perioperative (including donor) factors often are outside the control of hepatologists and transplant surgeons. This review is not an inclusive review of the literature but summarizes what we believe are the more controversial topics of this disease.

Acute rejection in HCV-infected liver transplant recipients: The great conundrum

1. In hepatitis C virus (HCV)-infected patients, treatment of acute rejection is associated with worse outcomes (increased risk of allograft cirrhosis and mortality). 2. Whether patients with HCV are at higher risk for rejection remains controversial. 3. The mechanisms mediating acute rejection and recurrence of HCV are distinct, and as such, it should be possible to develop techniques based on these molecular differences that are diagnostically useful. 4. Liver biopsy is considered the gold-standard for diagnosing acute rejection and recurrent HCV; however, given histopathological similarities between the two conditions, discrimination can be extremely difficult. 5. At the present time, there are no reliable, noninvasive tools available to distinguish between HCV recurrence alone and acute rejection plus HCV recurrence. 6. Mild rejection per se is not associated with graft loss and treatment of rejection with steroids and OKT3 is associated with worse outcome in HCV; thus, it seems logical that we should no longer treat mild rejection.