Rejection In Pediatric Heart Transplantation Research Articles

Gene Expression Profiling in Pediatric Heart Transplant Rejection

Purpose Gene expression profiling (GEP) has demonstrated utility in identifying heart transplant (HTx) patients at increased risk for acute rejection (AR) in adult populations. GEP has not been well studied in pediatric HTx patients whose immune system function may differ from adults. Improved understanding of alterations in gene expression between AR and quiescence may be beneficial in pediatric HTx recipients. Methods and Materials Blood samples were prospectively collected from pediatric HTx recipients (aged 1-18 years) who had undergone transplant at least six months prior to enrollment. Samples were collected over one year, at six month intervals and at time of AR. Acute rejection was defined as clinically indicated augmentation of immunosuppression which in some patients was accompanied by abnormal echocardiogram or biopsy. GEP of 84 genes in the inflammatory cascade (chemokines, cytokines and their receptors) was performed on peripheral mononuclear lymphocytes by commercially available PCR (Illumina Biosciences) array. Expression profiles were analyzed with the commonly used Significant Analysis of Microarray (SAM). Comparison was within individual at time of AR and quiescence. The genes that differentially expressed with and without AR were identified by controlling the false discovery rates at 5%. Results Gene expression profiling was conducted on 17 blood samples (AR and quiescent) from five subjects. A total of 47331 transcripts from the 84 genes were analyzed. Expression levels of defensin family of genes were significantly higher at the time of at AR than at the time of quiescence. This pattern was consistent in 3 of 5 subjects. Conclusions Gene expression profiling holds promise in identifying specific regulatory pathways or gene families with differential activity at times of AR in pediatric HTx recipients. The gene family identified in this study is different from those identified in adult HTx recipients. Further study could lead to improved ability to modulate immunosuppression and/or predict impending AR.

389 Is Adolescence an Independent Risk Factor for Rejection in Pediatric Heart Transplantation, Independent of Age at Listing?

389 Is Adolescence an Independent Risk Factor for Rejection in Pediatric Heart Transplantation, Independent of Age at Listing?

11-OR: HLA-G II Genotype and Low Levels of sHLA-G Post-Tx are Associated With First Year Rejection in Pediatric Heart Transplantation

11-OR: HLA-G II Genotype and Low Levels of sHLA-G Post-Tx are Associated With First Year Rejection in Pediatric Heart Transplantation

317: Cell Bound Complement Activation Products as Biomarkers of Humoral Rejection in Pediatric Heart Transplantation

317: Cell Bound Complement Activation Products as Biomarkers of Humoral Rejection in Pediatric Heart Transplantation

Pre-implantation Basiliximab Reduces Incidence of Early Acute Rejection in Pediatric Heart Transplantation

Basiliximab is an anti-CD25 monoclonal antibody used as induction therapy in solid-organ transplantation. In this study we aim to determine whether pre-operative administration of basiliximab is beneficial in preventing early heart allograft rejection. In this investigation we assess the effect of pre-implantation basiliximab on CD25 count and on acute rejection in children undergoing cardiothoracic transplantation. The notes of all children undergoing cardiothoracic transplantation at the Great Ormond Street Hospital between January 2000 and June 2007 were retrospectively reviewed. One hundred twenty-one heart transplant recipients were included: 29 patients did not receive basiliximab; 33 patients received basiliximab after coming off cardiopulmonary bypass (CPB); and 59 patients received basiliximab prior to organ implantation. All patients receiving basiliximab had an effectively suppressed CD25 count (<0.2%) on Days 1 and 10 post-transplant. Freedom from Grade 3A or greater rejection in the first year was significantly greater in the pre-implantation basiliximab group than in the post-implantation and no-basiliximab groups (95%, 70% and 72%, respectively; p = 0.02). Induction regimen was the only significant explanatory variable after multivariate Cox regression. The results of this study confirm that basiliximab is effective at suppressing CD25 count whether given pre- or post-CPB. Basiliximab before transplantation appeared to reduce acute rejection, whereas post-CPB administration did not suggest similar effects. These findings require independent validation in randomized trials and further studies should seek to mechanistically delineate these observations.

Genetic Polymorphisms Impact the Risk of Acute Rejection in Pediatric Heart Transplantation: A Multi-Institutional Study

The objective of this study was to determine the association between the genetic polymorphisms of proinflammatory and regulatory cytokines and long-term rates of repeat and late acute rejection episodes in pediatric heart transplant (PHTx) recipients. Three hundred twenty-three PHTx recipients: 205 White non-Hispanic, 43 Black non-Hispanic, and 75 Hispanic were analyzed for time to first repeat and late acute rejection episodes by race, age at transplantation, and gene polymorphism (interleukin [IL]-6, -174 G/C, IL-10, -1082 G/A, -819 C/T, 592 C/A; vascular endothelial growth factor (VEGF) -2578 C/A, -460 C/T, +405 C/G; tumor necrosis factor alpha (TNF-alpha)-308 G/A). Recipient black race and older age at transplant were risk factors for both repeat and late rejections, though black race was more significantly related to late rejection (P=0.006). Individually, TNF-alpha high, IL-6 high, VEGF high, and IL-10 low phenotypes did not impact the risk of repeat or late rejection. However, the combination VEGF high/IL-6 high and IL-10 low was associated with increased estimated risk of late rejection (P=0.0004) and only marginally with repeat rejection (P=0.051). In a multivariate analysis, adjusting for age and race, VEGF high/IL-6 high and IL-10 low still remained an independent risk factor for late acute rejection (RR=1.91, P<0.001). This is the largest multicenter study to document the impact of genetic polymorphism combinations on PHTx recipients' outcome. The high proinflammatory (VEGF high/IL-6 high) and lower regulatory (IL-10 low) cytokine gene polymorphism profile exhibited increased risk for late rejection, irrespective of age and race/ethnicity.

40-OR: The combination high VEGF/high IL-6 and low IL-10 gene polymorphism impact the risk of acute rejection in pediatric heart transplantation – a multicenter study

40-OR: The combination high VEGF/high IL-6 and low IL-10 gene polymorphism impact the risk of acute rejection in pediatric heart transplantation – a multicenter study

31-P: HLA-A and HLA-B amino-acid triplet mismatching is associated with increased frequency of acute rejection in pediatric heart transplantation

31-P: HLA-A and HLA-B amino-acid triplet mismatching is associated with increased frequency of acute rejection in pediatric heart transplantation

OKT3 Treatment in Refractory Pediatric Heart Transplant Rejection

The anti-lymphocyte monoclonal antibody OKT3 has been shown to be effective in the management of steroid-resistant and/or fulminant heart transplant rejection in adults. In addition, some studies suggest that OKT3 may have a role in the management of transplant coronary artery disease (TxCAD). To date, there are limited data regarding the use of OKT3 treatment of refractory rejection or graft failure in children. Our study examines OKT3 treatment in steroid-resistant rejection, rejection with hemodynamic compromise, and TxCAD in children. Thirty-eight patients received 53 courses of OKT3 for treatment of rejection and/or graft dysfunction. Primary indications for OKT3 were steroid-resistant rejection (n = 27), rejection with hemodynamic compromise (n = 22), and TxCAD (n = 4). Resolution of rejection was considered absence of biopsy-proven rejection (< grade 2) or resolved TxCAD. OKT3 use in steroid-resistant rejection was associated with a lower incidence of rejection in the 3 months after OKT3 than 3 months before OKT3, median rejection episodes of 2.5 vs 0, p < 0.0001. In rejection with hemodynamic compromise, 20 subjects (91%) demonstrated improved hemodynamics after OKT3 and survived to hospital discharge. The use of OKT3 treatment for TxCAD failed to demonstrate resolution or improvement in angiographic TxCAD in any subject. Only 5 OKT3 treatment courses were stopped secondary to severe adverse side effects. OKT3 treatment in refractory pediatric heart transplant rejection is efficacious in acute rejection. OKT3 management in pediatric TxCAD is less clear, with no proven benefit identified in this study. OKT3 use in pediatric refractory heart rejection has significant side effects, but is tolerable and safe with close monitoring.

Impact of ELISA-Detected Anti-HLA Antibodies on Pediatric Cardiac Allograft Outcome

In this study, we determine whether the presence of enzyme-linked immunosorbent assay (ELISA) detected anti-human leukocyte antigen (HLA) antibodies correlates with acute and chronic rejection in pediatric heart transplantation (Tx). Forty-five patients, who had serial ELISA pre- and posttransplantation, were studied. Age at Tx was 8.2 ± 7.2 years. Acute rejection (AR) was defined as International Society for Heart and Lung Transplantation Grade ≥3a. Patients were defined as rejectors (22 cases) if they had recurrent AR or steroid-resistant AR within the first year post-Tx; the other cases (23) were defined as nonrejectors. Overall, 219 samples were analyzed. Twenty-two of the 45 had pre- or post-Tx anti-HLA antibodies: 77% in rejectors (17/22) and only 22% in nonrejectors (5/23), p = 0.0002. Pre-Tx HLA antibodies were present in 12 cases (27%). Presensitization was more frequent in rejectors (11/22, 50%) than in nonrejectors (1/23, 4%, p = 0.0005). Nineteen cases retained (9 cases) or developed (10 cases) anti-HLA antibodies post-Tx: 14 in rejectors (63.6%) and 5 in nonrejectors (21.7%), p = 0.003. Four of eight cases with coronary artery disease (50%) had preformed anti-HLA antibodies compared with 8 of 37 without coronary artery disease (25.6%) ( p = 0.09). Preformed, persistent, and de novo ELISA-detected anti-HLA antibodies were correlated with first-year acute rejection profile.

Interleukin-10 production genotype protects against acute persistent rejection after lung transplantation

Background Our previous studies demonstrated that cytokine gene polymorphisms are related to acute rejection in pediatric heart transplantation; a decreased tumor necrosis factor (TNF)–α production genotype combined with an increased or intermediate interleukin (IL)–10 production genotype was associated with the smallest incidence of acute rejection. The objective of this study was to determine whether cytokine genotypes TNF-α, IL-10, IL-6, interferon-γ, and transforming growth factor β were associated with acute persistent rejection after lung transplantation. Methods Cytokine genotyping was performed in 119 adult lung transplantation recipients who underwent surveillance transbronchial biopsies during their first year after transplantation. We categorized recipients with acute persistent rejection if they had 2 consecutive biopsy specimens at ≥Grade A2 despite anti-rejection treatment. We performed cytokine genotyping using the polymerase chain reaction–sequence specific primers technique, with a commercially available kit. Results We analyzed the IL-10 genotype in 116 patients. For the increased IL-10 production genotype, 7 of 20 patients (35%) were persistent rejecters. In comparison, 57 of 96 patients (59%) with intermediate or decreased IL-10 production genotype had acute persistent rejection ( p = 0.046). For IL-10 haplotypes associated with intermediate IL-10 production, 30 of 45 patients with GCC/ACC haplotype (67%) had acute persistent rejection compared with 10 of 22 patients with GCC/ATA (45%). In the patients with intermediate IL-10 production, 17 of 22 (77%) with IL-10 GCC/ACC and IL-6 G/C had acute persistent rejection, whereas only 2 of 7 patients (29%) with IL-10 GCC/ATA and IL-6 G/G had acute persistent rejection ( p = 0.018). Conclusions In lung transplant recipients, the increased IL-10 production genotype protects against acute persistent rejection when compared with the intermediate or decreased IL-10 production genotypes. The intermediate IL-10 production genotype in lung transplant recipients can be differentiated into 2 haplotype responses, with the GCC/ACC haplotype associated more with acute persistent rejection. In lung transplant recipients, the immunomodulatory effects of IL-6 are differentiated in the G/C and G/G alleles in conjunction with IL-10 haplotypes, with G/C being associated with more acute persistent rejection in conjunction with the IL-10 GCC/ACC haplotype. Future pharmacogenomic models may incorporate these associations with acute persistent rejection in lung transplant recipients to formulate individualized therapeutic regimens.

Risk factors for recurrent rejection in pediatric heart transplantation: a multicenter experience

Background Cardiac allograft rejection remains as a primary cause of death in the first 3 years after pediatric heart transplantation. Multiple episode of acute rejection in adult heart transplant recipients may accelerate the development of graft vasculopathy. We sought to quantify the time-related probability of recurrent rejection and identify risk factors for the development of recurrent rejection. Methods We analyzed data from 847 pediatric recipients who underwent transplantation between January 1, 1993 and December 31, 1998 at 22 centers in the Pediatric Heart Transplant Study (PHTS). Recurrent rejection and risk factors were evaluated using univariate and multivariate analyses. Results Five hundred fifty two patients had 1,072 rejection events and were the subject of the analyses. The highest risk of recurrent rejection occurs within 1 month after resolution of a previous rejection episode. Risk factors for recurrent rejection include the number of previous rejection events, the elapsed time since a previous rejection episode, and subjects of either Hispanic or African-American descent. Rejection associated with hemodynamic compromise and late rejection is associated with higher mortality. Conclusions Recurrent rejection is a risk factor for mortality, especially in the presence of hemodynamic compromise. This association appears independent of the time post-transplantation. Use of surveillance biopsies appears warranted throughout the life of the transplant individual. Retransplantation should be considered among these subjects with recurrent rejection.

IL-10 high genotype is protective against acute persistent rejection after lung transplantation

Our previous studies have demonstrated that cytokine gene polymorphisms are related to acute rejection in pediatric heart transplantation. The objective of this study was to determine whether cytokine genotypes of TNF-α, IL-10, IL-6, interferon-γ, and transforming growth factor-β were associated with episodes of acute persistent rejection (APR) after lung transplantation (LT).

Total lymphoid irradiation for refractory rejection in pediatric heart transplantation

Background We evaluated the role of total lymphoid irradiation (TLI) in the management of refractory rejection among pediatric heart transplant patients. Methods Eleven of 298 patients underwent TLI at 6 to 195 months of age and were divided into subgroups: those who survived (group A, n = 7) and those who did not survive beyond 1 year after TLI (group D, n = 4). Non–TLI recipient data were considered as the controls. Results Six out of 11 patients died eventually (54%). TLI was initiated 3 to 107 months after transplantation with a dosage of 600 to 840 cGy. The pre-TLI rejection rate (0.62 ± 0.40 per month) was higher ( p < 0.0001); however, the post-TLI rejection rate (0.24 ± 0.65 per month) showed no significant difference from the control rejection rate. The Cox proportional hazard model found significance for TLI as a risk factor for development of posttransplant coronary artery disease (relative risk, 4.8; 95% CI, 1.1 to 21.3) and posttransplant lymphoproliferative disease (relative risk, 47.9; 95% CI, 1.6 to 1,475.3), respectively. Although the rejection rate decreased after TLI in both groups (group A pre/post, 0.51 ± 0.31/0.06 ± 0.08 per month; group D pre/post, 0.82 ± 0.49/0.57 ± 1.09 per month), significance was obtained only in group A ( p = 0.018). Conclusions TLI was an effective adjunct for reversal of refractory rejection in pediatric heart transplantation by reducing the rejection rate. Great care must be taken for the risk of development of coronary artery disease or lymphoproliferative disease.

Non-invasive assessment of rejection in pediatric transplant patients: serologic and echocardiographic prediction of biopsy-proven myocardial rejection

Background: Cardiac allograft rejection is a multifocal immune process that is currently assessed using biopsy-guided histologic classification systems (International Society for Heart and Lung Transplantation). Cardiac troponin T and I are established serologic markers of global myocyte damage. The use of load-independent measures of contractility have also been shown to accurately assess the presence of ventricular dysfunction. Little is known about their utility in accurately predicting rejection in the pediatric age group. We undertook the present study to compare rejection grade with echocardiographic and serologic estimates of transplant rejection–related myocardial damage. Methods We compared histologic rejection grades (0 to 4) with patient characteristics, echocardiographic measurements, catheterization measurements, and biochemical markers for 86 evaluations in 37 transplant recipients at Children’s Hospital. Results In univariate analyses, biopsy scores correlated ( p < 0.05) inversely with left ventricular systolic function (shortening fraction) and contractility (stress velocity index, SVI), and directly with mitral E-wave amplitude. In multivariate analyses, lower contractility and higher mitral E-wave amplitude remained significantly ( p ≤ 0.01) associated with rejection (SVI, p = 0.002, odds ratio = 0.393; E wave, p = 0.0002, odds ratio = 228). Most rejection episodes were associated with elevation of biochemical markers of myocardial injury. Although troponin I was weakly associated with differences between rejection grades ( p = 0.034), troponin T, creatine kinase–MB fraction, and C-reactive protein did not differ with biopsy-rejection scores. Serum markers had a poor predictive capacity for biopsy-detected rejection. Troponin T and I did correlate with increased left ventricular wall thickness and mass. Conclusion Progressively depressed left ventricular contractility and diastolic function are found with worsening pediatric heart transplant rejection–biopsy score; however, sensitive and specific serum markers do not correspond to the degree of active myocardial injury. The use of echocardiographic measures of contractility is associated with a specificity of 91.8% but low sensitivity of 66.7%. Overall we found poor concordance between serum markers and grade of rejection. It is unclear whether myocardial injury as assessed by serum markers, echocardiography, or histologic scoring is more important for assessment of acute rejection or long-term outcome, but it does not appear that serum and tissue markers of rejection can be used interchangeably.

Noncompliance causing late acute rejection in pediatric heart transplantation: JM Ringewald, SS Gidding, DF Wax, SE Crawford, S Rodgers, SR Shah, E Pahl, CL Backer, C Mavroudis. Children's Memorial Hospital, Northwestern University Medical School, Chicago, IL

Noncompliance causing late acute rejection in pediatric heart transplantation: JM Ringewald, SS Gidding, DF Wax, SE Crawford, S Rodgers, SR Shah, E Pahl, CL Backer, C Mavroudis. Children's Memorial Hospital, Northwestern University Medical School, Chicago, IL