Predictors of cytomegalovirus disease among pediatric transplant recipients within one year of renal transplantation

Care of Pediatric Solid Organ Transplant Recipients: An Overview for Primary Care Providers

As the number of living pediatric solid organ transplant (SOT) recipients continues to grow, there is an increased likelihood that primary care providers (PCPs) will encounter pediatric SOT recipients in their practices. In addition, as end-stage organ failure is replaced with chronic medical conditions in transplant recipients, there is a need for a comprehensive approach to their management. PCPs can significantly enhance the care of immunosuppressed hosts by advising parents of safety considerations and avoiding adverse drug interactions. Together with subspecialty providers, PCPs are responsible for ensuring that appropriate vaccinations are given and can play an important role in the diagnosis of infections. Through early recognition of rejection and posttransplant complications, PCPs can minimize morbidity. Growth and development can be optimized through frequent assessments and timely referrals. Adherence to immunosuppressive regimens can be greatly improved through reinforcement at every encounter, particularly among adolescents. PCPs can also improve long-term outcomes by easing the transition of pediatric SOT recipients to adult providers. Although guidelines exist for the primary care management of adult SOT recipients, comprehensive guidance is lacking for pediatric providers. In this evidence-based overview, we outline the main issues affecting pediatric SOT recipients and provide guidance for PCPs regarding their management from the first encounter after the transplant to the main challenges that arise in childhood and adolescence. Overall, PCPs can and should use their expertise and serve as an additional layer of support in conjunction with the transplant center for families that are caring for a pediatric SOT recipient.

Cytomegalovirus and Epstein-Barr virus infections among pediatric kidney transplant recipients at a center using universal Valganciclovir Prophylaxis

BACKGROUND

CMV is associated with adverse effects in renal transplant recipients. The objective of this study was to characterize the incidence and timing of CMV and EBV infections in relation to valGCV prophylaxis in a pediatric renal transplant cohort.

METHODS

Retrospective cohort of pediatric renal transplant patients given universal valGCV prophylaxis and universal viral surveillance was evaluated. Demographics, prophylaxis, acute rejection, and CMV and EBV infections were abstracted.

RESULTS

A total of 92 pediatric renal allograft recipients, 2008-2013, were included. One or more viral infections developed in 77/92 (83.7%) of the patients. EBV was the most common in 62/92 (67%) patients, irrespective of valGCV (82% of episodes occurring on valGCV). CMV DNAemia occurred in 30/92 (33%) patients, 14 episodes (47%) occurring on valGCV. Incidence of breakthrough CMV on prophylaxis was 15% and was associated with persistent DNAemia (OR 7.8, CI:1.6-32.9, P < 0.02). CMV tissue-invasive disease was not seen. CMV syndrome occurred in 10% of the cohort, only in CMV D+ patients, and only one symptomatic breakthrough infection required treatment. Out of 92, 21 (23%) had simultaneous co-infections with 2-3 viruses.

CONCLUSIONS

Viral infections in pediatric renal transplant recipients receiving universal valGCV prophylaxis were common. EBV infections were not reduced by valGCV prophylaxis, and nearly half of CMV infections occurred on valGCV. Symptomatic CMV infection while on prophylaxis was rare. valGCV prophylaxis may prevent symptomatic CMV infection but not EBV infection, and frequent CMV surveillance in pediatric renal transplant recipients on prophylaxis may not be necessary.

Incidence, risk factors, and outcomes of opportunistic infections in pediatric renal transplant recipients

OIs present significant risks to patients following solid organ transplantation. The purpose of this study was to identify risk factors for the development of OIs after kidney transplantation in pediatric patients and to evaluate the impact of OIs on outcomes in this patient population. A single-center retrospective longitudinal cohort analysis including pediatric patients 21 yr of age or younger transplanted from July 1999 to June 2013 at an academic medical center was conducted. Patients were excluded if they received multi-organ transplant. A total of 175 patients were included in the study. Patients who developed OIs were more likely to be female and younger at the time of transplant. A six-factor risk model for OI development was developed. Death, disease recurrence, and PTLD development were similar between groups but trended toward increased incidence in the OI group. Incidence of rejection was significantly higher in the OI group (p = 0.04). Patients who developed OIs had several important risk factors, including younger age, EBV-negative serostatus, CMV donor (+)/recipient (-), biopsy-proven acute rejection, ANC <1000, MMF dose >500 mg/m(2), and any infection. Incidence of rejection was higher in the OI group, but rate of graft loss was not statistically different.

Cytomegalovirus prophylaxis in pediatric kidney transplantation: the Dutch experience

Many children receiving a kidney transplant are seronegative for CMV and therefore, highly susceptible to a primary CMV infection. This study aims at evaluating incidence, time of occurrence, and severity of CMV infection in the first year post-transplantation in relation to different types of CMV prophylaxis. Transplantations in three centers in the Netherlands between 1999 and 2010 were included. Retrospective, observational, multicenter study. Clinical data and PCR measurements of CMV were collected. Prophylaxis in high-risk patients (CMV serostatus D+R-) consisted of (val)ganciclovir during three months, or acyclovir plus CMV immunoglobulin at a former stage. Intermediate-risk patients (R+) received (val)acyclovir, or acyclovir plus CMV immunoglobulin at a former stage. Low-risk patients (D-R-) did not receive prophylaxis. Infection was defined as CMV PCR above 50 geq/mL plasma or whole blood, a clinically relevant infection above 1000 geq/mL. One hundred and fifty-nine transplantations were included. CMV infection was documented for 41% of high-risk, 24% of intermediate-risk, and 13% of low-risk patients, in the latter two groups typically during the first three months. The infection rate was highest in the high-risk group after cessation of valganciclovir prophylaxis. Valganciclovir provided better protection than did acyclovir + CMV immunoglobulin. Adding an IL2-receptor blocker to the immunosuppressive regimen did not affect the infection rate. Acute graft rejection was not related with CMV infection. Valganciclovir prophylaxis effectively prevents CMV infection in high-risk pediatric kidney recipients, but only during prophylaxis. Valacyclovir prophylaxis in intermediate-risk patients is less effective.

24 weeks of valganciclovir prophylaxis in children after renal transplantation: a 4-year experience

BACKGROUND

Cytomegalovirus (CMV) is the most common opportunistic infection after solid-organ transplant. Valganciclovir prophylaxis significantly reduces disease, but limited data are available on its use in children. Recently, an increase in delayed-onset CMV disease has been noted with some arguing that longer prophylaxis may decrease late-onset disease.

METHODS

Single-center, retrospective analysis of pediatric renal transplant patients receiving 24 weeks valganciclovir prophylaxis (15 mg/kg/day, maximum 900 mg/day) from January 2004 to December 2008, aiming to measure the incidence of CMV disease and toxicity of valganciclovir.

RESULTS

We enrolled 111 patients, 60% males, 46% African Americans, and median age at transplant 14.5 years (range 1.4-20.4 years). Sixty-nine percent of donors and 44% of recipients were seropositive pretransplant. Median duration of valganciclovir use was 5.9 months (range 0.5-24 months). CMV viremia and disease occurred in 27% and 4.5%, respectively. All patients with disease presented after prophylaxis ended and all were D+/R-. Thymoglobulin use (P = 0.04) and positive donor CMV status (P = 0.02) were associated with a higher risk of CMV viremia. Twenty-four percent had hematologic toxicity directly associated with valganciclovir.

CONCLUSIONS

Valganciclovir use in children was effective as prophylaxis against CMV disease; no children at our institution developed disease while on therapy. Our regimen of 24 weeks of prophylaxis was associated with a lower rate of late-onset disease than previous reports with 12-week regimens. Further controlled studies should be considered to compare longer versus shorter periods of prophylaxis and dose reductions and their impact on prevention of late-onset disease, resistance, cost, and toxicity.

The efficacy and safety of valganciclovir vs. oral ganciclovir in the prevention of symptomatic CMV infection in children after solid organ transplantation

Routine prophylaxis for CMV with valganciclovir is common in adult recipients but data to support its use in children are scarce. The aim of this study was to compare the efficacy and safety of valganciclovir vs. ganciclovir in a pediatric cohort. We performed a retrospective analysis of 92 children after KTx and/or LTx. All children have received IV ganciclovir for two wk, and then oral ganciclovir (TID; n = 41) before 2004, or valganciclovir (OD; n = 51) thereafter. Treatment was given for three months in R+/D+ or R+/D- recipients and for six months in R-/D+. Patients were followed for one yr post transplant. Both groups were comparable in their demographic and transplant-related history. Symptomatic CMV infection/disease developed in 13.7% vs. 19.5% of valganciclovir and ganciclovir groups, respectively (P-NS). Time-to-onset of CMV infection was comparable in both groups (P-NS); rates of acute allograft rejection were similar in both groups (3.9% vs. 9.8%). Risk factors for CMV infection included young age, serostatus of R-/D+, and allograft from cadaver donor. No significant side effects were noted in both groups. As in adults, valganciclovir appears to be as efficacious and safe as oral ganciclovir. Valganciclovir should be considered as a possible prophylactic treatment for CMV in pediatric recipients of KTx or LTx.

Active human cytomegalovirus infection and glycoprotein b genotypes in brazilian pediatric renal or hematopoietic stem cell transplantation patients

A prospective analysis of active Human Cytomegalovirus infection (HCMV) was conducted on 33 pediatric renal or hematopoietic stem cell post-transplant patients. The HCMV-DNA positive samples were evaluated for the prevalence of different gB subtypes and their subsequent correlation with clinical signs. The surveillance of HCMV active infection was based on the monitoring of antigenemia (AGM) and on a nested polymerase chain reaction (N-PCR) for the detection of HCMV in the patients studied. Using restriction analysis of the gB gene sequence by PCR-RFLP (Restriction Fragment Length Polymorphism), different HCMV strains could be detected and classified in at least four HCMV genotypes. Thirty-three pediatric recipients of renal or bone marrow transplantation were monitored. Twenty out of thirty-three (60.6%) patients demonstrated active HCMV infection. gB1 and gB2 genotypes were more frequent in this population. In this study, we observed that gB2 had correlation with reactivation of HCMV infection and that patients with mixture of genotypes did not show any symptoms of HCMV disease. Future studies has been made to confirm this.

Failure of immunosuppressive drug levels to predict T-cell reactivity in pediatric transplant patients

PURPOSE

In children, therapeutic management of immunosuppression relies on allograft function, drug levels, and clinical insight. Using a Food and Drug Administration-approved test for T-cell response, T-cell activation in vitro can be measured to monitor the immune response.

METHODS

In a retrospective study, 92 posttransplant children who received either a liver and/or kidney transplant and were followed by routine screening had their T-cell response tested by the Cylex ImmuKnow assay (Columbia, MD). After phytohemagglutinin-L stimulation of T-cells, adenosine triphosphate (ATP) concentrations were measured. In this assay, light emission at lambda = 562 nm is proportional to the ATP concentration (ng/mL). Immunosuppressive drug trough levels were also measured. Quantitative real-time polymerase chain reaction Epstein-Barr virus (EBV) viral titers were determined for 2 patients.

RESULTS

Separating the results into younger than 12 years and 12-year or older populations, we found that for the younger than 12 years, 28% of patients were in the low immune function category, 47% in the moderate, and 25% in the high category. For the 12 years or older, 25% of patients were in the low immune function category, 47% in the moderate, and 28% in the high category. The immune function distribution was not different (P = not significant) between the younger than 12 years and 12-year or older groups. Tacrolimus trough levels were 6.3 +/- 2.4 ng/mL for younger than 12 years and 5.6 +/- 3.3 ng/mL for 12 years or older (P = not significant), and rapamycin was similar, but both showed no correlation to immune function. We observed increased ATP values with decreased EBV viral loads.

CONCLUSIONS

These results suggest that tacrolimus and/or rapamycin levels do not adequately determine the biologic effect of immunosuppression. We expect that future T-cell activation monitoring will allow us to diminish rejection and infection events posttransplantation and lead to a healthier pediatric transplant population.

Acute rejection episodes in pediatric renal transplant recipients with cytomegalovirus infection

CMV infection is the most important opportunistic virus infection after renal transplantation leading to increased patient mortality, graft loss, risk for acute rejection episodes and impaired renal function. The potential impact of prophylactic anti-viral therapy on long-term graft outcome is relevant. The aim of this study was to evaluate the incidence of CMV infection, its risk factors and long-term outcome in children after renal transplantation. 103 children (mean age 10.6 +/- 5.3, range 1.6-22.0 yr) were monitored weekly for pp65 for the first 6-8 wk after renal transplantation, followed by a monthly monitoring for the first year. CMV infection occurred in 23/103 children (21.1%) with 10 patients (9.7%) developing CMV disease characterized by positive pp65 in the presence of organ involvement. The CMV R-/D+ and R+/D+ serostatus was significantly associated with an increased risk of CMV infection (p < 0.0001 and p = 0.009). 14/28 R-/D+ patients developed CMV infection despite prophylactic treatment with CMV hyperimmune globulin. The incidence of acute rejection episodes after or during CMV infection was significantly increased (p = 0.003) and the D+ serostatus was significantly associated with acute rejection episodes within the first year after transplantation (p = 0.006). In summary the overall incidence of CMV infection in this single center experience is 21.1%. The D+ serostatus represents a serious risk factor for both CMV infection and acute rejection episodes. In future the potential impact of different modalities of prophylactic anti-viral therapy on the prevention of acute rejection should be considered.

Prevention of CMV disease in pediatric kidney transplant recipients: evaluation of pp67 NASBA-based pre-emptive ganciclovir therapy combined with CMV hyperimmune globulin prophylaxis in high-risk patients

A new prevention strategy for CMV infection was evaluated in our pediatric kidney transplant unit. This approach comprises a pre-emptive therapy, based upon the monitoring of CMV pp67 mRNA in whole blood by the qualitative NASBA, combined with prophylactic CMV-IG in high risk (R-/D+) children. Thirty-one kidney transplant children were followed for six months with serial measurements of CMV pp67 mRNA in the blood. The R-/D+ patients were given prophylactic CMV-IG for the first 16 wk after transplantation. I.v. ganciclovir was administered upon CMV detection by NASBA and was discontinued after two consecutive negative results. CMV infection, detected by NASBA, developed in 11 (35%) recipients: one (33%) of the R+/D- patients and 10 (72%) of the R-/D+ patients. CMV disease developed in 9.6% of the patients (3/31), exclusively in the R-/D+ group. These three patients presented concurrently with CMV viremia and disease. It is noteworthy that two of the three patients could not receive a complete course of CMV-IG, and one of the latter two subjects had been treated for acute rejection 15 days before CMV infection. Ganciclovir was given for the 11 cases of primary infection, and for three cases of relapsed CMV infection. pp67 NASBA-based pre-emptive ganciclovir therapy, combined with prophylactic CMV-IG in high-risk patients leads to a lower rate of CMV disease, as long as a complete course of CMV-IG has been administered and ganciclovir is given during the period of treatment for acute rejection in high-risk populations.

Acceleration of allograft failure by cytomegalovirus

A number of human herpesviruses are important opportunistic pathogens that have been associated with increased morbidity and mortality in transplant recipients including human cytomegalovirus (HCMV), HHV6, HHV7, HHV8 as well as HSV-1, VZV. However, HCMV has been linked both epidemiologically and through the use of animal models to the acceleration of acute and chronic allograft rejection. This review will cover the pathophysiology, epidemiology, and mechanisms of CMV-associated disease in the setting of transplantation.

Pediatric renal transplantation: a single center experience over 14 years

Between 1989 and 2003, 100 transplants were performed in 96 patients at the pediatric nephrology unit of the Calvo Mackenna Children's Hospital. Mean age 10.9 +/- 3.9 yr (1-17.6), 30% from LD. Donors were younger than 5 yr in five patients and all recipients received an 'en bloc' graft. Original disease was hypo/dysplasia 27%, reflux nephropathy 22 and 17% chronic glomerulonephritis. The immunosuppressive protocol during the first period (n = 56, 1989-2000): Cyclosporine, steroids and azathioprine, and during the second period (n = 44, 2001-2003): FK, steroids, MMF and anti-CD25 antibody (mAbs). AR was reported in 22 patients, 11% in LD, 31% in DD (p < 0.01). The AR rate decreased from 40 to 8% after anti-CD25 monoclonal induction. Patient actuarial survival rate at 1, 3 and 5 yr was 100% for LD and 96% for DD. The overall actuarial graft survival at 1,3, and 5 yr was 96.7, 96.7 and 71% for LD and 89, 76 and 73% for DD donors. Graft survival rate improved from the first period (1989-2000) to the second period (2001-2003; p = 0.05). No difference in graft survival rate with HLA-A,B,DR matching was found. Graft survival rate was better when cold ischemia time was <24 h (p < 0.01). CMV infections increased from 19 to 40% when MMF and anti-CD25 Ab were introduced (p < 0.01). The height/age Z score at 1, 3 and 5 yr post-transplant was -2.2, -2.1, -2.2, respectively, for children older than 7 yr and -1.8, -1.9, -2.1 for those transplanted younger than 7 yr of age who were switched to alternate day steroids (p < 0.01). The cause of graft lost was: chronic rejection eight, non-adherence four, AR four and vascular thrombosis two. The cause of death in two patients was fungus septicemia and accelerated rejection. Pediatric renal transplantation can be performed in our group with acceptable morbidity, low mortality and graft survival rates similar to other reports in North America and Western Europe. Graft survival rate improved with newer immunosuppression and greater experience at the center. Management of non-adherence and chronic rejection remain the major challenges.

DermaVir: A Novel Topical Vaccine for HIV/AIDS

Human immunodeficiency virus (HIV) vaccines have the potential to improve antiretroviral drug treatment by inducing cytotoxic killing of HIV-infected cells. Prophylactic vaccines utilize new antigens to initiate immunity; however, in HIV-infected individuals the load of viral antigen is not the limiting factor for the restoration of immune responses. Here we describe a novel immunization strategy with DermaVir that improves viral antigen presentation using dendritic cells (DC). DermaVir contains a distinctive plasmid DNA expressing all HIV proteins except integrase to induce immune responses with broad specificity. The DNA is formulated to a mannosilated particle to target antigen-presenting cells and to protect the DNA from intracellular degradation. After topical application, DermaVir-transduced cells migrate from the skin to the draining lymph node and interdigitate as DermaVir-expressing, antigen-presenting DC. We compared the immunogenicity of topical and ex vivo DC-based DermaVir vaccinations in naive rhesus macaques. Both vaccinations induced simian immunodeficiency virus-specific CD4 helper and CD8 memory T cells detected by an in vivo skin test and an in vitro intracellular cytokine-based assay. Topical DermaVir vaccination represents an improvement upon existing ex vivo DC-based immunization technologies and may provide a new therapeutic option for HIV-infected patients.

Continued superior outcomes with modification and lengthened follow-up of a steroid-avoidance pilot with extended daclizumab induction in pediatric renal transplantation1

BACKGROUND

Corticosteroids have been invariant transplant immunosuppressives with numerous adverse effects. We previously reported 6-month results in 10 patients using extended daclizumab induction to safely eliminate steroid use in pediatric renal transplantation. This expanded pilot series discusses immunosuppression dosing modification to further minimize drug toxicity without sacrificing regimen efficacy.

METHODS

Fifty-seven pediatric renal transplant recipients were enrolled in the pilot steroid-free protocol. Extended daclizumab induction, tacrolimus, and mycophenolate mofetil (MMF) were intended maintenance drugs. Fourteen patients were equal to or younger than 5 years, and 43 patients were older than 5 years of age at transplantation. There were seven protocol breaks. Study patients underwent serial protocol transplant biopsies (n=246), and serum daclizumab and mycophenolic acid (MPA) trough levels were evaluated. In this efficacy study, controls were 50 historical-matched steroid-based children receiving tacrolimus with 100% 2-year graft survival and without delayed graft function.

RESULTS

Mean follow-up was 20 (range, 4.5-41) months with 98% overall graft and patient survival. At 1 year of analysis, steroid-free recipients showed significant improvements for clinical acute rejection (8%), graft function, hypertension, and growth, without increased infectious complications. Leukopenia, anemia, and allograft nephrotoxicity were addressed by solely decreasing MMF and tacrolimus dosing and/or by replacing MMF with sirolimus, without increasing acute rejection. Early daclizumab levels of more than 5 microg/mL were observed for the first time in children of all ages.

CONCLUSIONS

Pediatric renal transplantation is safe without steroids. Daclizumab first-dose doubling and extended use for 6 months replaces steroids effectively without evidence of overimmunosuppression and may be the pivotal cause for the reduced acute rejection seen in this trial. This pilot study provides preliminary data to test this protocol in a prospective, multicenter randomized study.

Influence of intrauterine injection of rat fetal hepatocytes on rejection of rat liver transplantation

AIM: To investigate the influence of immune tolerance induced by intrauterine exposure to fetal hepatocytes on liver transplantation in the adult rat.

METHODS: LOU/CN rat fetal hepatocytes were injected into the fetuses of pregnant CHN rats (14-16 days of gestation). At 7-9 weeks of age, the surviving male rats received orthotopic liver transplantation (OLT) from male LOU/CN donors and the survival period was observed and monitered by mixed lymphocyte reaction assay and cytotoxicity test.

RESULTS: (1) A total of 31 pregnant CHN rats with 172 fetuses received fetal hepatocytes from LOU/CN rats via intrauterine injection. Among them, thirteen pregnant rats showed normal parturition, with 74 neonatal rats growing up normally. (2) The mean survival period after OLT in rats with fetal exposure to fetal hepatocytes was 32.1 ± 3.7 days, which was significantly different from the control (11.8 ± 2.3 days, P < 0.01) in rats without fetal induction of immune tolerance. (3) Mixed lymphocyte proliferation assays yielded remarkable discrepancies between the groups of rats with- or without fetal exposure to fetal hepatocytes, with values of 8411 ± 1361 and 22473 ± 1856 (CPM ± SD, P < 0.01) respectively. (4) Cytotoxicity assays showed values of 21.2 ± 6.5% and 64.5 ± 7.2% (P < 0.01) in adult rats with or without fetal induction of immune tolerance.

CONCLUSION: Intrauterine injection of fetal hepatocytes into rat fetuses can prolong the survival period of liver transplant adult male rats recipients, inducting immune tolerance in OLT.