Cytomegalovirus-associated allograft rejection in heart transplant patients

Treatment of cytomegalovirus infections beyond acute disease to improve human health

Human cytomegalovirus is a common virus that establishes latency and persistence after a primary infection in 50-90% of populations worldwide. In otherwise healthy persons, the infection is generally mild or asymptomatic, although it may cause mononucleosis, prolonged episodes of fever, and hepatitis. However, in AIDS patients and transplant recipients who are immunosuppressed, severe, life-threatening infections may develop. CMV is also the most common congenital infection and may cause birth defects and deafness. Emerging evidence shows a high prevalence of this virus in patients with chronic inflammatory diseases or tumours of different origin, such as breast, colon, and prostate cancer, neuroblastoma, medulloblastoma, and glioblastoma. Several drugs are available to treat CMV infections. This review will highlight the possibility of using anti-CMV therapy to improve outcome not only in patients with acute CMV infections but also in patients with inflammatory diseases and cancer.

Opportunistic infections--coming to the limits of immunosuppression?

Possible etiologies of infection in the solid organ recipient are diverse, ranging from common bacterial and viral pathogens to opportunistic pathogens that cause invasive disease only in immunocompromised hosts. The recognition of infectious syndromes in this population is limited by alterations in the clinical manifestations by immunosuppression. The risk of serious infections in the organ transplant patient is determined by the interaction between the patients' recent and distant epidemiological exposures and all factors that contribute to the patient's net state of immune suppression. This risk is altered by antimicrobial prophylaxis and changes in immunosuppressive therapies. In addition to the direct effects of infection, opportunistic infections, and the microbiome may adversely shape the host immune responses with diminished graft and patient survivals. Antimicrobial therapies are more complex than in the normal host with a significant incidence of drug toxicity and a propensity for drug interactions with the immunosuppressive agents used to maintain graft function. Rapid and specific microbiologic diagnosis is essential. Newer microbiologic assays have improved the diagnosis and management of opportunistic infections. These tools coupled with assays that assess immune responses to infection and to graft antigens may allow optimization of management for graft recipients in the future.

Cytomegalovirus infections in solid organ transplantation: a review

Cytomegalovirus (CMV) continues to have a tremendous impact in solid organ transplantation despite remarkable advances in its diagnosis, prevention and treatment. It can affect allograft function and increase patient morbidity and mortality through a number of direct and indirect effects. Patients may develop asymptomatic viremia, CMV syndrome or tissue-invasive disease. Late-onset CMV disease continues to be a major problem in high-risk patients after completion of antiviral prophylaxis. Emerging data suggests that immunologic monitoring may be useful in predicting the risk of late onset CMV disease. There is now increasing interest in the development of an effective vaccine for prevention. Novel antiviral drugs with unique mechanisms of action and lesser toxicity are being developed. Viral load quantification is now undergoing standardization, and this will permit the generation of clinically relevant viral thresholds for the management of patients. This article provides a brief overview of the contemporary epidemiology, clinical presentation, diagnosis, prevention and treatment of CMV infection in solid organ transplant recipients.

Management strategies for cytomegalovirus infection and disease in solid organ transplant recipients

Cytomegalovirus is the most common viral pathogen that affects solid organ transplant recipients. It directly causes fever, myelosuppression, and tissue-invasive disease, and indirectly, it negatively impacts allograft and patient survival. Nucleic acid amplification testing is the preferred method to confirm the diagnosis of CMV infection. Prevention of CMV disease using antiviral prophylaxis or preemptive therapy is critical in the management of transplant patients. Intravenous ganciclovir and oral valganciclovir are the first line drugs for antiviral treatment. This article provides a comprehensive review of the current epidemiology, diagnosis, prevention and treatment of CMV infection in solid organ transplant recipients.

Endothelial dysfunction and cardiac allograft vasculopathy

Cardiac allograft vasculopathy remains a major challenge to long-term survival after heart transplantation. Endothelial injury and dysfunction, as a result of multifactorial immunologic and nonimmunologic insults in the donor and the recipient, are prevalent early after transplant and may be precursors to overt cardiac allograft vasculopathy. Current strategies for managing cardiac allograft vasculopathy, however, rely on the identification and treatment of established disease. Improved understanding of mechanisms leading to endothelial dysfunction in heart transplant recipients may provide the foundation for the development of sensitive screening techniques and preventive therapies.

Clues to the etiology of bile duct injury in biliary atresia

Biliary atresia (BA) is an infantile obstructive cholangiopathy of unknown etiology with suboptimal therapy, which is responsible for 40 to 50% of all pediatric liver transplants. Although the etiology of bile duct injury in BA in unknown, it is postulated that a pre- or perinatal viral infection initiates cholangiocyte apoptosis and release of antigens that trigger a Th1 immune response that leads to further bile duct injury, inflammation, and obstructive fibrosis. Humoral immunity and activation of the innate immune system may also play key roles in this process. Moreover, recent investigations from the murine BA model and human data suggest that regulatory T cells and genetic susceptibility factors may orchestrate autoimmune mechanisms. What controls the coordination of these events, why the disease only occurs in the first few months of life, and why a minority of infants with perinatal viral infections develop BA are remaining questions to be answered.

Everolimus is associated with a reduced incidence of cytomegalovirus infection following de novo cardiac transplantation

BACKGROUND

Cytomegalovirus (CMV) causes several complications following cardiac transplantation including cardiac allograft vasculopathy. Previous studies suggested that immunosuppressive treatment based on everolimus might reduce CMV infection. Aiming to better characterize the action of everolimus on CMV and its interplay with patient/recipient serology and anti-CMV prophylaxis, we analyzed data from 3 large randomized studies comparing various everolimus regimens with azathioprine (AZA)- and mycophenolate mofetil (MMF)-based regimens.

METHODS

CMV data were analyzed from 1009 patients in 3 trials of de novo cardiac transplant recipients who were randomized to everolimus 1.5 mg/day, everolimus 3 mg/day, or AZA 1-3 mg/kg/day, plus standard-dose (SD) cyclosporine (CsA; study B253, n = 634); everolimus 1.5 mg/day plus SD- or reduced-dose (RD)-CsA (study A2403, n = 199); and everolimus 1.5 mg/day plus RD-CsA or MMF plus SD-CsA (study A2411, n = 176).

RESULTS

In study B253, patients allocated to everolimus experienced almost a 70% reduction in odds of experiencing CMV infection compared with AZA (P < 0.001). In study A2403, CMV infection was low in both everolimus arms, irrespective of CsA dosing, and in study A2411, patients allocated to everolimus experienced an 80% reduction in odds of experiencing CMV infection, compared with MMF (P < 0.001). CMV syndrome/disease was rare and less frequent in everolimus-treated patients. Subgroup analyses showed that the benefit everolimus provides, in terms of CMV events, is retained in CMV-naïve recipients and is independent of anti-CMV prophylaxis or preemptive approaches.

CONCLUSIONS

Everolimus is associated with a lower incidence of CMV infection compared with AZA and MMF, which combined with its immunosuppressive efficacy and antiproliferative effects may positively impact long-term outcomes.

An important role for autoimmunity in the immunopathogenesis of chronic allograft rejection

Organ transplantation is the treatment of choice for patients with end-stage organ dysfunction. In spite of advances in understanding of donor and recipient physiology, organ preservation, operative techniques and immunosuppression, long-term graft survival still remains a major problem primarily due to chronic rejection. Alloimmune responses to mismatched major histocompatibility antigens have been implicated as an important factor leading to rejection. However, there is increasing evidence pointing towards cross-talk between the alloimmune and autoimmune responses creating a local inflammatory milieu, which eventually leads to fibrosis and occlusion of the lumen in the transplanted organ i.e. chronic rejection. In this review, we will discuss recent studies and emerging concepts for the interdependence of alloimmune and autoimmune responses in the immunopathogenesis of chronic allograft rejection. The role of autoimmunity in the development of chronic rejection is an intriguing and exciting area of research in the field of solid-organ transplantation with a significant potential to develop novel therapeutic strategies towards preventing chronic allograft rejection.

Prophylaxis of cytomegalovirus disease in mismatched patients after heart transplantation using combined antiviral and immunoglobulin therapy

BACKGROUND

Cytomegalovirus (CMV) is a common cause of infection and morbidity after heart transplantation. Seronegative recipients (R-) of seropositive donor hearts (D+) are at high risk for CMV disease. We compared three different CMV prophylaxis regimens using combined antiviral and immunoglobulin therapy.

METHODS

In 99 patients who survived more than 30 days after heart transplant, all received induction with antilymphocytic therapy and triple-drug therapy. In group A, D+R- patients received one dose of intravenous immunoglobulin (IVIG) followed by one dose of CMV-specific immunoglobulin (CMV-IVIG), and intravenous ganciclovir (GCV) for 4 weeks followed by 11 months of oral acyclovir (ACV). In group B, D+R- patients received one dose IVIG followed by five doses of CMV-IVIG and intravenous GCV for 14 weeks followed by 9 months of oral ACV. In group C, D+R- patients were treated with the same regimen as for group B, except oral ACV was replaced with oral GCV.

RESULTS

The actuarial freedom from CMV disease for D+R- patients at 1 month, 1 year, and 2 years after transplantation in group A was 100%, 25% ± 15%, and 25% ± 15%, respectively; group B was 100%, 67% ± 27%, and 67% ± 27%; group C was 100%, 83% ± 15%, and 83% ± 15% (P < .01, groups B and C vs group A). By comparison, the actuarial freedom from CMV disease for seropositive recipients (D-R+ or D+R+) at 1 month, 1 year, and 2 years in group A was 100%, 87% ± 7%, and 82% ± 8%, respectively; group B was 100%, 88% ± 8%, and 75% ± 11%; group C was 100%, 72% ± 9%, and 72% ± 9% (P = NS among groups). Rejection rates did not differ among the three groups.

CONCLUSIONS

A longer course of intravenous GCV with multiple doses of CMV-IVIG was a more effective prophylaxis regimen against CMV disease for the high-risk group of seronegative recipients of seropositive donor hearts.

The search for new therapies for human cytomegalovirus infections

Ganciclovir (GCV), the therapy of choice for human cytomegalovirus (CMV) infections and foscarnet, a drug used to treat GCV-resistant CMV infections was approved more than twenty years ago. Although cidofovir and a prodrug of GCV have since been added to the armamentarium, a highly effective drug without significant toxicities has yet to be approved. Such a therapeutic agent is required for treatment of immunocompromised hosts and infants, which bear the greatest burden of disease. The modest antiviral activity of existing drugs is insufficient to completely suppress viral replication, which results in the selection of drug-resistant variants that remain pathogenic, continue to replicate, and contribute to disease. Sustained efforts, largely in the biotech industry and academia, have identified highly active lead compounds that have progressed into clinical studies with varying levels of success. A few of these compounds inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapies. Some of the more promising drugs will be discussed with an emphasis on those progressing to clinical studies. Their antiviral activity both in vitro and in vivo, spectrum of antiviral activity, and mechanism of action will be reviewed to provide an update on the progress of potential new therapies for CMV infections.

Disseminated intravascular coagulation complicating Epstein-Barr virus infection in a cardiac transplant recipient: a case report

Viral infections are particularly common after cardiac transplantation. Herein we have presented a case of Epstein-Barr infection that presented as a viral syndrome with respiratory symptoms, but was complicated by multiorgan failure and disseminated intravascular coagulation. Transplant physicians should be aware of this unique complication of an otherwise self-limited infection.

Defining the risks for cytomegalovirus infection and disease after solid organ transplantation

Cytomegalovirus continues to be one of the most clinically significant infections after solid organ transplantation. Classic definitions of patients at high risk for infection and tissue-invasive disease are focused on recipient-donor serostatus, type of organ transplanted, and overall level of immunosuppression. However, recent trends in clinical practice call for a reevaluation of cytomegalovirus infection risks after solid organ transplantation. Indeed, whereas early-onset cytomegalovirus infection is usually controlled by antiviral prophylaxis with ganciclovir and derivatives, delayed- and late-onset cytomegalovirus infection can develop after the completion of a course of preventive therapy. In addition, indirect effects of cytomegalovirus infection may occur as a result of persistent low-level viremia. Suboptimal dosing of antiviral drugs due to specific drug toxicities may result in the development of ganciclovir-resistant cytomegalovirus disease. The relationship between organ allograft rejection and cytomegalovirus infection and disease has been recognized for some time. Transplantation of increasing numbers of extended-criteria donor organs increases the risk of delayed graft function and acute rejection, prompting the use of more intensive immunosuppression. In addition, the trend to spare long-term exposure to calcineurin inhibitors has contributed to a resurgence in the use of polyclonal T-cell induction immunosuppressive agents, which may reduce host anticytomegalovirus immunity. We discuss the current trends in solid organ transplantation that provide a foundation for defining risks for cytomegalovirus infection and disease, including identification of patients who would benefit from more aggressive cytomegalovirus monitoring and prevention strategies.

Changing trends in infectious disease in heart transplantation

BACKGROUND

During the past 25 years, advances in immunosuppression and the use of selective anti-microbial prophylaxis have progressively reduced the risk of infection after heart transplantation. This study presents a historical perspective of the changing trends of infectious disease after heart transplantation.

METHODS

Infectious complications in 4 representative eras of immunosuppression and anti-microbial prophylaxis were analyzed: (1) 38 in the pre-cyclosporine era (1978-1980), (2) 72 in the early cyclosporine era (1982-1984), where maintenance immunosuppression included high-dose cyclosporine and corticosteroid therapy; (3) 395 in the cyclosporine era (1988-1997), where maintenance immunosuppression included cyclosporine, azathioprine, and lower corticosteroid doses; and (4) 167 in the more recent era (2002-2005), where maintenance immunosuppression included cyclosporine and mycophenolate mofetil.

RESULTS

The overall incidence of infections decreased in the 4 cohorts from 3.35 episodes/patient to 2.03, 1.35, and 0.60 in the more recent cohorts (p < 0.001). Gram-positive bacteria are emerging as the predominant cause of bacterial infections (28.6%, 31.4%, 51.0%, 67.6%, p = 0.001). Cytomegalovirus infections have significantly decreased in incidence and occur later after transplantation (88 +/- 77 days, pre-cyclosporine era; 304 +/- 238 days, recent cohort; p < 0.001). Fungal infections also decreased, from an incidence of 0.29/patient in the pre-cyclosporine era to 0.08 in the most recent era. A major decrease in Pneumocystis jiroveci and Nocardia infections has also occurred.

CONCLUSIONS

The overall incidence and mortality associated with infections continues to decrease in heart transplantation and coincides with advances in immunosuppression, the use of selective anti-microbial prophylaxis, and more effective treatment regimens.

The pathophysiology of chronic graft failure in the cardiac transplant patient

Following cardiac transplantation, many patients develop chronic deterioration of graft function, which may lead to a clinical syndrome similar to native chronic heart failure (CHF). This condition of chronic cardiac graft failure (CGF) may also share pathophysiological processes comparable with that of CHF. However, the unique environment following cardiac transplantation may also contribute with a variety of unique mechanisms, deserved of special attention. This review article discusses the complex pathophysiology of CGF after cardiac transplantation, an important yet neglected condition of transplant medicine.

Prophylaxis versus preemptive anti-cytomegalovirus approach for prevention of allograft vasculopathy in heart transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection may influence the development of cardiac allograft vasculopathy (CAV). Prophylactic or preemptive administration of anti-CMV agents effectively prevents acute CMV manifestations. However, studies comparing allograft-related outcomes between these anti-CMV approaches are lacking. Herein we report a longitudinal observational study comparing CAV development between prophylactic and preemptive approaches.

METHODS

The 1-year change in maximal intimal thickening (MIT) assessed by intravascular ultrasound at 1 and 12 months after heart transplantation (the major surrogate for late survival) was compared in groups of patients routinely assigned to a preemptive strategy (from November 2004 to October 2005; n = 21) or receiving valganciclovir prophylaxis (from November 2005 to October 2006; n = 19). CMV infection was monitored with pp65 antigenemia.

RESULTS

The 1-year increase in MIT was significantly lower in patients receiving prophylaxis compared with those managed preemptively (0.15 +/- 0.17 vs 0.31 +/- 0.20 mm; p = 0.01). Prophylaxed recipients presented less frequently with MIT change > or =0.3 mm (p = 0.03) and > or =0.5 mm (p = 0.10) than those managed preemptively. Prophylaxis was also associated with later onset of CMV infection (p = 0.01), lower peak CMV detection (p < 0.01) and reduced incidence of CMV disease/syndrome (p = 0.04). After adjusting for metabolic risk factors and other possible confounders, prophylaxis remained independently associated with lower risk for MIT change > or =0.3 mm (odds ratio = 0.09, 95% confidence interval 0.01 to 0.93; p = 0.04).

CONCLUSIONS

Universal prophylaxis was associated with delayed onset of CMV infection, lower viral burden, reduced CMV disease/syndrome and less intimal thickening, as compared with a preemptive anti-CMV approach. Randomized studies are required to confirm the potential benefits of prophylaxis vs a preemptive approach in heart transplant recipients.

Immune monitoring of anti cytomegalovirus antibodies and risk of cytomegalovirus disease in heart transplantation

We sought to determine whether quantitative assessment of anti-cytomegalovirus (CMV) antibodies could be useful to identify patients at risk of cytomegalovirus (CMV) disease after heart transplantation (HT). 75 patients who underwent HT at a single health care center were prospectively studied. Induction therapy included 2 doses of daclizumab and maintenance tacrolimus (n=42) or cyclosporine (n=29), mycophenolate mofetil and prednisone. All patients received prophylaxis with gancyclovir or valganciclovir. Anti-CMV intravenous immunoglobulin (CMV-IG) was added in high risk patients (CMV D+/R- serostatus). Serial determinations of anti-CMV antibodies, immunoglobulins (IgG, IgA, IgM) and IgG-subclasses were analysed. CMV infection was based on detection of the virus by antigenemia. CMV disease consisted of detection of signs or symptoms attributable to this microorganism. Ten patients (13.3%) developed CMV disease. Mean time of development of CMV disease was 3.4+/-1.6 months. In Cox regression analysis, patients with low baseline anti-CMV titers (<4.26 natural logarithm of titer, RH: 8.1, 95%CI: 1.93-34.1, p=0.004) and recipients with 1-month post-HT IgG hypogammaglobulinemia (IgG<500 mg/dl, RH: 4.49, 95%CI: 1.26-15.94, p=0.02) were at higher risk of having CMV disease. Despite use of prophylactic CMV-IG, D+/R- patients showed significantly lower titers of anti-CMV antibodies at 7 d, 30 d and 90 d post HT as compared with HT recipients without infections. Four out of 6 of these patients developed late CMV disease. Monitoring of specific anti-CMV antibodies on the bedside warrants further evaluation as a potential tool to identify heart transplant recipients at higher risk of CMV disease.