HEPATITIS B AND TRANSPLANTATION

Systematic review of hepatocellular carcinoma mortality rates among hepatitis B virus-infected renal transplant recipients, with supplemental analyses of liver failure and all-cause mortality

OBJECTIVES

The purpose of this review was to compare the mortality rates for hepatocellular carcinoma (HCC) among hepatitis B surface antigen (HBsAg)-seropositive renal transplant (RT) patients versus HBsAg-seropositive persons of the general population.

METHODS

A comprehensive search was performed to identify cohort studies of HBsAg-seropositive RT patients with at least 4 years of follow-up. Data were analyzed as outlined below. HCC was a rare event in regions of low and intermediate seroprevalence of HBsAg. Subsequently, studies from low and intermediate seroprevalence areas were analyzed separately from those of high seroprevalence areas.

RESULTS

Thirty-one retrospective studies that followed 1277 seropositive RT patients were identified for inclusion. The studies were pooled and compared to four different general population studies that included 12558 seropositive persons using Poisson methods. The mortality rate of HCC was increased in low and intermediate seroprevalence areas (RR 7.67, 95% confidence interval (CI) 3.93-15.0; RR 9.92, 95% CI 5.38-18.3). In high seroprevalence areas, the mortality rate of HCC was increased compared to one population study, but not another (RR 2.76, 95% CI 1.64-4.63; RR 1.02, 95% CI 0.61-1.69).

CONCLUSIONS

Mortality due to HCC was increased in low and intermediate seroprevalence areas, but the evidence was inconclusive for high seroprevalence areas.

Occult hepatitis B virus infection and cryptogenic chronic hepatitis in an area with intermediate prevalence of HBV infection

AIM: To assess the possible role of occult HBV infection in the pathogenesis of chronic hepatitis in Iranian patients.

METHODS: After exclusion of autoimmune, metabolic and viral etiologies, 104 consecutive adult patients with histologic and biochemical features of chronic hepatitis and negative HBsAg were enrolled in the study. Qualitative PCR with a sensitivity of 150 × 10³ copies/L, using two primers for Pre-S and core regions was applied to measure presence of HBV DNA in serum of the patients.

RESULTS: All 104 patients completed the study. Qualitative HBV DNA was positive in two patients (1.9%).

CONCLUSION: Occult HBV infection has negligible role in the pathogenesis of cryptogenic chronic hepatitis in Iranian patients.

Outcome of renal transplantation in hepatitis B surface antigen-positive patients after introduction of lamivudine

BACKGROUND

In end-stage renal disease patients with hepatitis B surface antigen (HBsAg), the risk of hepatic dysfunction after immunosuppression represents a large barrier in renal transplantation. Lamivudine is a potent inhibitor of hepatitis B virus (HBV) replication. We retrospectively investigated the outcome of HBsAg-positive renal transplantation recipients after lamivudine had become available.

METHODS

From July 1994 to August 2000, seventeen HBsAg-positive patients (M:F=15:2) received renal allografts (13:4=living:cadaveric donors). Liver function tests at the time of transplantation were normal in all patients. Pre-transplant liver biopsies performed in 15 patients demonstrated minimal inflammatory histology, except in three patients showing pathological and clinical signs of active hepatitis. Lamivudine was started pre-operatively in these three subjects. Another seven patients were treated with lamivudine for post-operative hepatic dysfunction. The remaining seven patients did not develop hepatic dysfunction after transplantation.

RESULTS

Lamivudine was initially effective in decreasing serum HBV DNA titres, and in normalizing hepatic enzymes. Lamivudine was well tolerated without significant side effects for 35.5+/-8.9 months after initiation of treatment. HBV DNA became negative in nine patients but remained positive in one patient. Among the nine patients with initial negative conversion of HBV DNA, two developed transient positive conversion of HBV DNA and two demonstrated persistent positive conversion. Among the patients with normal liver histology in the pre-transplant period, 41.6% (5/12) developed liver pathology progression after immunosuppression. All 17 patients had functioning grafts, except for one patient who developed relapsed IgA nephropathy.

CONCLUSIONS

Our data showed relatively favourable outcomes in hepatitis B-positive renal transplant recipients receiving lamivudine treatment, even though two patients developed lamivudine resistance.

Infections in recipients of kidney transplants

A review of infections in kidney transplant recipients is presented in this article, beginning with a discussion of the pretransplant infectious diseases evaluation and an overview of the timing of infectious posttransplant, and then focusing on individual types of infection.

Pretransplant evaluation for infections in donors and recipients of solid organs

The risk of infectious disease reactivation in recipients of and transmission by solid-organ transplants remains, and thorough screening and testing of recipient and donor is especially important. In conceiving screening strategies, it is crucial to consider the sensitivity and specificity of individual diagnostic tests in the context of their use. Furthermore, recognition of special risks for infectious complications of transplantation will help to guide preventive, diagnostic, and therapeutic steps in the control of infectious complications in individual patients. The acceptability of risks for infectious complications after transplantation depends also on the urgency of transplantation of a vital organ as well as the availability of organs. Although these principals are well accepted, standards for the extent of screening and criteria for inappropriate donors and exclusion of unfit recipients remain controversial to some extent.

Infectious disease issues in xenotransplantation

Xenotransplantation, the transplantation of living organs, tissues, or cells from one species to another, is viewed as a potential solution to the existing shortage of human organs for transplantation. While whole-organ xenotransplantation is still in the preclinical stage, cellular xenotransplantation and extracorporeal perfusion applications are showing promise in early clinical trials. Advances in immunosuppressive therapy, gene engineering, and cloning of animals bring a broader array of xenotransplantation protocols closer to clinical trials. Despite several potential advantages over allotransplantation, xenotransplantation encompasses a number of problems. Immunologic rejection remains the primary hindrance. The potential to introduce infections across species barriers, another major concern, is the main focus of this review. Nonhuman primates are unlikely to be a main source for xenotransplantation products despite their phylogenetic proximity to humans. Genetically engineered pigs, bred under special conditions, are currently envisaged as the major source. Thus far, there has been no evidence for human infections caused by pig xenotransplantation products. However, the existence of xenotropic endogenous retroviruses and the clinical evidence of long-lasting porcine cell microchimerism indicate the potential for xenogeneic infections. Thus, further trials should continue under regulatory oversight, with close clinical and laboratory monitoring for potential xenogeneic infections.

Hepatitis B in transplantation

Hepatitis B has been a major challenge within the field of transplantation over the past few decades. Due to aggressive recurrence post-transplant, patients with hepatitis B have been excluded from the benefits of both solid organ and bone marrow transplants. Progress has been made, however, through an improved understanding of the biology of hepatitis B and the development of new antiviral strategies that can reliably suppress the virus. Patients with hepatitis B are now candidates for transplantation in an increasing number of circumstances. Careful pre-transplant evaluation is mandatory, together with a tailored antiviral regimen depending on the replicative status of the virus and the organ being transplanted. Minimizing steroid dose following transplantation is an important part of the strategy to reduce the risk of viral reactivation. Lamivudine has been an important development and it has assumed an increasing role in the management of these patients. As additional antivirals are developed, increasingly effective drug combinations will prevent viral recurrence as well as the emergence of drug-resistant mutants, which plagues the use of single agents. It is a rapidly evolving field and there is every reason for continued optimism.

Infectious complications in renal transplant recipients

Infectious complications present major challenges to physicians caring for renal transplant recipients. The high rate of infection reflects the net state of immunosuppression associated with end-stage renal disease, transplantation, donor and environmental exposure. An understanding of the factors that affect the patients' overall state of immunosuppression is essential to prevent and treat infectious complications, which may lead to significant morbidity, graft dysfunction, or mortality. Familiarity with the various pathogens, clinical presentation, diagnostic options, treatment, and prophylaxis is important to care for renal transplant patients. The authors present their approach, based on review of current literature, to these issues.

Treatment of chronic hepatitis B with lamivudine in renal transplant recipients

BACKGROUND

Lamivudine is a potent inhibitor of hepatitis B virus replication. Little has been reported about the efficacy and safety of lamivudine in the treatment of chronic hepatitis B in the setting of renal transplantation.

METHODS

Two patients were treated for chronic hepatitis B with lamivudine and subsequently underwent renal transplantation. Four other patients were treated with lamivudine for reactivation of hepatitis B after renal transplantation. Chronic hepatitis B was proven histologically in all the patients. The doses of lamivudine ranged from 100 to 150 mg/day. Hepatic enzyme and viral markers were monitored.

RESULTS

Lamivudine was well tolerated for a median duration of 8 months (range, 4-14 months) without significant side effects. Viral replication was suppressed, as evidenced by negative conversion of serum hepatitis B virus DNA in all the patients. Hepatic enzyme was also normalized. Modification of doses of immunosuppressant regimen was not required in using lamivudine in all patients. One patient experienced acute rejection and responded to solumedrol pulse therapy with normalization of graft function. Normal graft function was maintained in other patients while they were treated with lamivudine.

CONCLUSION

Lamivudine was a safe and effective therapy for activated hepatitis B in renal transplant recipients in the short term.

Diagnostic tools in the evaluation of patients with viral hepatitis undergoing liver transplantation

Familiarity with the diagnostic parameters of viral hepatitis is imperative in the liver transplantation arena. Chronic viral hepatitis B and C are among the most common categories of end-stage liver disease. The preoperative diagnosis, determination of recurrent infection, and the assessment of antiviral therapeutic efficacy are dependent on appropriate virological testing. Furthermore, liver transplant personnel are at a high risk for parenterally transmitted viral hepatitis infection. Knowledge and understanding of the serological patterns of acute and chronic viral hepatitis, as well as recognition of the immune status for one or more of these viruses, will facilitate prevention and treatment of viral hepatitis for these health care providers.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.