Michael Melter

CNS or Bone Marrow Involvement As Risk Factors for Poor Survival in Post-Transplantation Lymphoproliferative Disorders in Children After Solid Organ Transplantation

PURPOSE To identify prognostic factors of survival in pediatric post-transplantation lymphoproliferative disorder (PTLD) after solid organ transplantation. PATIENTS AND METHODS A multicenter, retrospective case analysis of 55 pediatric solid organ graft recipients (kidney, liver, heart/lung) developing PTLD were reported to the German Pediatric-PTLD registry. Patient charts were analyzed for tumor characteristics (histology, immunophenotypes, cytogenetics, Epstein-Barr virus [EBV] detection), stage, treatment, and outcome. Probability of overall and event-free survival was analyzed in defined subgroups using univariate and Cox regression analyses. RESULTS PTLD was diagnosed at a median time of 29 months after organ transplantation, with a significantly shorter lag time in liver (0.83 years) versus heart or renal graft recipients (3.33 and 3.10 years, respectively; P = .001). The 5-year overall and event-free survival was 68% and 59%, respectively, with 59% of patients surviving 10 years. Stage IV disease with bone marrow and/or CNS involvement was associated independently with poor survival (P = .0005). No differences in outcome were observed between early- and late-onset PTLD, monomorphic or polymorphic PTLD, and EBV-positive or EBV-negative PTLD, respectively. Patients with Burkitt or Burkitt-like PTLD and c-myc translocations had short survival (< 1 year). CONCLUSION Stage IV disease is an independent risk factor for poor survival in pediatric PTLD patients. Prospective multicenter trials are needed to delineate additional risk factors and to assess treatment approaches for pediatric PTLD.

The role of the graft endothelium in transplant rejection: Evidence that endothelial activation may serve as a clinical marker for the development of chronic rejection

Abstract: In this review, we discuss the role of the allograft endothelium in the recruitment and activation of leukocytes during acute and chronic rejection. We discuss associations among endothelial activation responses, the expression of adhesion molecules, chemokines and chemokine receptors, and rejection; and we propose that endothelial vascular cellular adhesion molecule‐1 (VCAM‐1) may be used as a surrogate marker of acute rejection and allograft vasculopathy. In addition, we describe potential mechanistic interpretations of persistent endothelial cell (EC) expression of major histocompatibility complex (MHC) class II molecules in allorecognition. The graft endothelium may provide an antigen‐specific signal to transmigrating, previously activated, T cells and may induce B7 expression on locally transmigrating leukocytes to promote costimulation. Taken together, these functions of the EC provide it with a potent regulatory role in rejection and in the maintenance of T‐cell activation via the direct and/or the indirect pathways of allorecognition.

The CD40-induced signaling pathway in endothelial cells resulting in the overexpression of vascular endothelial growth factor involves Ras and phosphatidylinositol 3-kinase.

Ligation of endothelial cell (EC) CD40 induces the expression of several proinflammatory cytokines as well as angiogenesis factors, including vascular endothelial growth factor (VEGF). Moreover, despite the reported importance of CD40 in cell-mediated immunity, little is known of the CD40-induced signaling pathways in EC. In this study, we have investigated the function of the Ras signaling pathway(s) for CD40-induced overexpression of VEGF. EC were transiently transfected with a full-length VEGF promoter-luciferase construct and a dominant-inhibitory mutant of Ras (Ras17N). Following transfection, ligation of CD40 with soluble CD40 ligand resulted in a significant increase in VEGF transcriptional activation, and the inhibitory mutant of Ras blocked this CD40-induced VEGF overexpression. Using EMSA and Western blot analysis, we demonstrated that CD40-dependent binding of nuclear protein(s) to the VEGF promoter and CD40-induced VEGF protein expression in EC were also inhibited by the Ras mutant. Immunoprecipitation studies revealed that ligation of CD40 on EC promoted an increased association of Ras with its effector molecules Raf, Rho, and phosphatidylinositol 3-kinase (PI3K). But, cotransfection of effector-loop mutants of Ras determined that only PI3K was functional for Ras-induced VEGF transcription. Also, wortmanin and a dominant-inhibitory mutant of PI3K inhibited CD40-induced overexpression of VEGF. Together these findings demonstrate that both Ras and PI3K are intermediaries in CD40-induced regulation of VEGF in EC. We believe our findings are of importance in several chronic inflammatory diseases, including atherosclerosis and allograft rejection associated with both CD40-CD40 ligand signaling as well as VEGF expression and function.

Liver transplantation in children with chronic end stage liver disease: factors influencing survival after transplantation.

To identify pretransplant factors that are influencing survival after orthotopic liver transplantation a Cox proportional hazards regression model was applied to 118 children with chronic terminal liver failure transplanted at Medical School Hannover during the period of 1978 to 1994. The response variable was survival, as covariates a total of 19 pretransplant variables were entered--i.e. age, diagnosis (biliary cirrhosis, metabolic cirrhosis, postnecrotic cirrhosis, cryptogenetic cirrhosis) sex, laparotomy prior to OLT, height, weight, standard deviation scores for height and weight, date of first OLT, serum alanine aminotransferase, asparagine aminotransferase, albumin, total bilirubin, cholinesterase activity, glomerular filtration rate, and prothrombin time. Significant independent predictors of survival after OLT were bilirubin (P=0.0024), SDS for weight (P=0.034), and albumin (P=0.039). In a subsequent discriminant analysis cut off points for these variables could be identified--i.e., bilirubin >340 micromol/L, SDS for weight <-2.2 and albumin < 33 g/L. Patients with one or more of these risk factors were grouped as urgent indication group (n=76) and those with no risk factor as elective indication group (n=42). Comparing the posttransplantation survival in these groups there is a statistically significant difference at 1 year (57% vs. 90.5%) and 4 years (49% vs. 90.5%) after OLT (P=0.0001, log rank test). It is concluded that the risk of OLT is much higher if liver function is very poor. Optimal nutritional support prior to transplantation is mandatory to optimise the clinical status of the children and to improve the results of OLT.

Current understanding of chemokine involvement in allograft transplantation

Abstract: Multiple studies have demonstrated that chemokines play an essential role in regulating and co‐ordinating the infiltration of leucocytes into allografts. Chemokines are expressed in skin, liver, heart, and kidney allografts following initial engraftment, ischemic injury, viral infection, and acute and chronic rejection. To date, most of our understanding of chemokine biology has been generated from studies of animal models of transplantation and little is known about the role of chemokines in human allograft rejection. Chemokines may play important mechanistic roles in transplant rejection, in the development of graft arteriosclerosis, and in chronic sclerosing cholangiopathy. Furthermore, these molecules may serve as sensitive diagnostic indicators for the analysis of rejection, including chronic rejection or other forms of graft dysfunction. Lastly, it is possible that chemokine‐targeted therapy might become a feasible option for the treatment of allograft rejection.

Improvement of Growth After Growth Hormone Treatment in Children Who Undergo Liver Transplantation

Background Chronic liver insufficiency in children is frequently associated with growth retardation. Growth resumes after successful orthotopic liver transplantation in the majority of children with previous chronic liver failure. However, a subgroup of children demonstrates stunted growth even after orthotopic liver transplantation. The current study was conducted to determine whether administration of recombinant human growth hormone might benefit these patients. Methods Ten children were identified who met the criteria of growth failure despite normal transplant function in a cohort of 60 transplantation patients: height standard deviation score (hSDS) for chronological age less than −2, and growth velocity SDS (gvSDS) for chronological age equaling 0. Seven of these patients were treated with subcutaneous injections of recombinant human growth hormone at 4.0 U/m2 body surface area per day for at least 1 year. Two patients in this group showed insufficient growth hormone response to stimulation (arginine, clonidine) before therapy. Treatment was begun after a median time of 4.6 years after liver transplantation (2.55–8.4 years). Five children were treated with cyclosporin A and prednisolone and two with tacrolimus and prednisolone for maintenance immunosuppression. Results Within 3 months of treatment, median serum levels of insulin-like growth factor (IGF)-I increased from 0.05 to 0.71 (P < 0.02). Within 1 year, median hSDS improved from −2.7 (range, −5.6 to −2.3) to −2.1 (−4.5 to −1.4;P < 0.03). Median annual growth rate increased from 3.9 cm/year (range, 3–6) in the year before treatment to 8.2 cm/year (range, 6.1–10.4;P < 0.02) after the beginning of recombinant human growth hormone therapy. All patients tolerated treatment without side effects. During the cumulative treatment time of 14 years no rejection episode was observed. Conclusions Short-statured prepubertal liver transplant recipients who do not show sufficient compensatory growth after transplantation benefit from treatment with recombinant human growth hormone. Treatment with the hormone was safe without any side effects.

Renal arterial resistance index and computerized quantification of fibrosis as a combined predictive tool in chronic allograft nephropathy

Abstract:  The renal arterial resistance index (RI) and the PicroSiriusRed stained cortical fractional interstitial fibrosis volume (VintFib) proved to be two independent methods that are reliable predictive factors of poor renal allograft outcome. No data have been published, which define the correlation between ultrasound assessment and quantitative morphologic changes. Renal biopsies were performed in 56 children according to increases in s‐creatinine >10%. VintFib was calculated by computerized image analysis. RI was determined in two segmental arteries, 1 yr after transplantation and at the time‐point of biopsy. RIs 1 yr after transplantation correlated significantly with RIs at time of biopsy (r = 0.58, p < 0.001). VintFib was higher in children with a RI = 80 than in children with a RI < 80 (mean VintFib = 9.5 ± 3.2% vs. 5.2 ± 5.1%, p = 0.004). In children with VintFib > 10%, the mean RI was 77 ± 5 compared with 69 ± 6 in patients with VintFib < 10% (p = 0.0002). The highest positive predictive value to detect the risk of decline of GFR at 2 yr after biopsy was 98% when an RI = 80% was associated with a VintFib > 10%. For VintFib > 10% or RI = 80 alone, it was 87% or 67%, respectively. The combined measurement of RI and VintFib is a reliable predictive tool for the risk of developing long‐term graft dysfunction after kidney transplantation.

Current developments in pediatric liver transplantation

In 1953, the pioneer of human orthotopic liver transplantation (LT), Thomas E Starzl, was the first to attempt an orthotopic liver transplant into a 3 years old patient suffering from biliary atresia. Thus, the first LT in humans was attempted in a disease, which, up until today, remains the main indication for pediatric LT (pLT). During the last sixty years, refinements in diagnostics and surgical technique, the introduction of new immunosuppressive medications and improvements in perioperative pediatric care have established LT as routine procedure for childhood acute and chronic liver failure as well as inherited liver diseases. In contrast to adult recipients, pLT differs greatly in indications for LT, allocation practice, surgical technique, immunosuppression and post-operative life-long aftercare. Many aspects are focus of ongoing preclinical and clinical research. The present review gives an overview of current developments and the clinical outcome of pLT, with a focus on alternatives to full-size deceased-donor organ transplantation.

Prediction of survival in extrahepatic biliary atresia by hepatic duplex sonography

BACKGROUND The clinical course of biliary atresia patients is extremely variable. To optimize conservative treatment and correctly schedule liver transplantation, noninvasive investigations that are predictive of individual survival and that can be performed regularly are needed. In this study, the prognostic value of Doppler sonography was investigated in these patients. METHODS Thirty biliary atresia patients (age range, 1 month to 15.2 years; mean, 4.0 years) and 38 control subjects underwent standardized Doppler sonography of liver and spleen. Biochemical tests of liver function and of fibrogenesis were performed in parallel. Individual clinical outcome was registered 1 and 2 years later. RESULTS In control subjects, maximum portal flow velocity (Vmax) was more than 16 cm/sec, and the hepatic vein flow pattern was triphasic. Among children with biliary atresia, those with diminished portal Vmax, a flattened hepatic vein flow curve, or a hepatic artery resistance index of 0.8 or more had significantly lower indices of hepatic protein synthesis (albumin, cholinesterase), higher bilirubin levels, and higher concentrations of markers of connective tissue turnover (procollagen peptides, laminin P1) than did those with normal Doppler sonography measurements. The rate of survival without transplantation during the following 2 years was significantly lower in children with abnormal Doppler findings. From portal and hepatic vein flow measurements, patient survival 2 years later could be predicted with an accuracy of 93%. CONCLUSIONS In children with extrahepatic biliary atresia, Doppler sonography of the hepatic blood flow is a noninvasive indicator of disease severity. Moreover, it allows a highly accurate prediction of patient survival for the following 2 years.

Chemokines and their receptors in human clinical solid organ transplantation

Chemokines and chemokine receptors are expressed in solid organ allografts after ischemia reperfusion injury, acute and chronic rejection and in association with viral infections. The importance of the biology of chemokines and their receptors has been established in several animal models and in humans. Here we discuss evidence for a role for chemokine–chemokine receptor interactions in many posttransplant inflammatory processes. Most compelling are findings that some inducible chemokine receptors are functional in the process of allograft rejection. We discuss evidence that CCR1, CCR5, and CXCR3, interacting with their chemokine ligands—regulation on activation, normal T cell expressed and secreted (RANTES); interferon-inducible protein 10 (IP-10); and monokine induced by interferon-&ggr; (Mig)–are of significance in human allograft rejection. These molecules are functional in rejection, but they may also serve as sensitive diagnostic markers and predictors of patients at risk of rejection or other forms of clinical graft dysfunction. Chemokine receptors warrant consideration as potential therapeutic targets in the future.