[Renal transplantation - new developments]

Renal transplantation has become an established option for renal replacement therapy in many patients with end stage renal disease. Living donation is a possibility for timely transplantation, hampered in 20 % of all possible donors and recipients byincompatible blood groups. AB0-incompatible renal transplantation overcomes this hurdle with acceptable allograft survival compared to conventional living-donor renal transplantation. During the last 10 years, the number of patients awaiting renal transplantation older than 65 years has nearly doubled. The decision to transplant those patients and their medical treatment is a growing challenge in transplantation. On the other hand donor age is increasing with potential negative consequences for long-term outcome of organ function. Antibody-mediated humoral rejection have been identified lately as an important cause for allograft failure during long-term follow up of renal transplant patients. New immunological methods to detect donor-specific antibodies, like solid-phase assays (Luminex®), have increased the knowledge and understanding of humoral rejection processes. This will lead hopefully to modified immunosuppressive strategies to minimize organ failure due to chronic rejection.

Demographics of blood pressure and hypertension in children on renal replacement therapy in Europe

Hypertension is a well-known complication in children on renal replacement therapy and an important risk factor for cardiovascular disease in later life. In order to define the prevalence of and risk factors for hypertension among children, we enrolled 3337 pediatric patients from 15 countries in the ESPN/ERA-EDTA Registry of whom 464 were on hemodialysis, 851 on peritoneal dialysis, and 2023 had received a renal allograft. Hypertension was defined as either systolic or diastolic blood pressures in the 95th percentile or greater for age, height, and gender or use of antihypertensive medication. Analyses were adjusted for age, gender, duration, and modality of renal replacement therapy. In 10 countries in which information on the use of antihypertensive medication was available, hypertension was present in over two-thirds of hemodialysis, peritoneal dialysis, or transplant patients. Blood pressure values above the 95th percentile were significantly more prevalent in very young patients (under 3 years) compared to 13- to 17-year olds (odds ratio 2.47), during the first year compared to over 5 years of renal replacement therapy (odds ratio 1.80), and in patients on hemodialysis compared to transplant recipients or those on peritoneal dialysis (odds ratios of 2.48 and 1.59, respectively). Over time, mean blood pressures decreased in both hemodialysis and transplant patients, but not in peritoneal dialysis patients. Hence, our findings highlight the extent of the problem of hypertension in children with end-stage renal disease in Europe.

Everolimus-based, calcineurin-inhibitor-free regimen in recipients of de-novo kidney transplants: an open-label, randomised, controlled trial

Non-nephrotoxic immunosuppressive strategies that allow reduction of calcineurin-inhibitor exposure without compromising safety or efficacy remain a goal in kidney transplantation. Immunosuppression based on the mammalian-target-of-rapamycin inhibitor everolimus was assessed as a strategy for elimination of calcineurin-inhibitor exposure and optimisation of renal-graft function while maintaining efficacy.

Long-term follow-up of lung and heart transplant recipients with pre-transplant malignancies

Concern regarding recurrence of pre-transplant (Tx) malignancy has disqualified patients from Tx. Because this has been poorly studied in lung and heart Tx recipients our aim was to investigate the influence of pre-Tx malignancy on post-Tx recurrence and long-term survival, focusing on pre-operative cancer-free intervals.

Improvement in renal function after everolimus introduction and calcineurin inhibitor reduction in maintenance thoracic transplant recipients: the significance of baseline glomerular filtration rate

The NOCTET (NOrdic Certican Trial in HEart and lung Transplantation) trial demonstrated that everolimus improves renal function in maintenance thoracic transplant (TTx) recipients. Nevertheless, introduction of everolimus is not recommended for patients with advanced renal failure. We evaluated NOCTET data to assess everolimus introduction amongst TTx recipients with advanced renal failure.

Immunosuppressive drugs in organ transplant recipients--rationale for critical selection

Transplantation is the treatment of choice for many different organ failures. Despite growing experience in surgery and immunosuppression protocols, the long-term mortality of the procedure remains much higher than in the general population. Second only to cardiovascular diseases as the cause of death in organ transplant recipients, cancer is now known to be at least partly related to the immunosuppression regimen. Nevertheless, if calcineurin inhibitors have a demonstrated pro-oncogenic effect, other classes, such as mTOR inhibitors, are antiproliferative, and even demonstrated as an efficient therapy in some advanced oncological situations. Therefore, the adaptation of the therapy protocol evolves now towards an individualized medicine based on the risk factors of each transplant recipient in terms of cardiovascular, infectious and oncological diseases. As the first organ involved by tumor is the skin, many different guidelines have been published to try and adapt the therapy to the occurrence of a new lesion. If, for example, limited actinic keratosis or the first episode of a non-melanoma skin cancer usually requires no change of the immunosuppressive therapy, but a local specialized care and frequent clinical controls, more advanced lesions imply the adaptation of the drug regimen. In any case, the collaboration between general practitioners, dermatologists and the transplantation team is mandatory.

Pre- and posttransplant management of solid organ transplant recipients: risk-adjusted follow-up

Solid organ transplant recipients (SOTR) have an increased risk of skin cancer due to their long-term immunosuppressive state. As the number of these patients is increasing, as well as their life expectancy, it is important to discuss the screening and management of skin cancer in this group of patients. The role of the dermatologist, in collaboration with the transplant team, is important both before transplantation, where patients are screened for skin lesions and the individual risk for skin cancer development is assessed, and after transplantation. Posttransplant management consists of regular dermatological consultations (the frequency depends on different factors discussed below), where early skin cancer screening and management, as well as patient education on sun protective behavior is taught and enforced. Indeed, SOTR are very sensitive to sun damage due to their immunosuppressive state, leading to cumulative sun damage which results in field cancerization with numerous lesions such as in situ squamous cell carcinoma, actinic keratosis and Bowen's disease. These lesions should be recognized and treated as early as possible. Therapeutic options discussed will involve topical therapy, surgical management, adjustment of the patient's immunosuppressive therapy (i.e. reduction of immunosuppression and/or switch to mammalian target of rapamycin inhibitors) and chemoprevention with the retinoid acitretin, which reduces the recurrence rate of squamous cell carcinoma. The dermatological follow-up of SOTR should be integrated into the comprehensive posttransplant care.

Seasonal variations of ventricular arrhythmia clusters in defibrillator recipients

BACKGROUND: Clustering ventricular arrhythmias are the consequence of acute ventricular electrical instability and represent a challenge in the management of the growing number of patients with an implantable cardioverter-defibrillator (ICD). Triggering factors can rarely be identified. OBJECTIVES: Several studies have revealed seasonal variations in the frequency of cardiovascular events and life-threatening arrhythmias, and we sought to establish whether seasonal factors may exacerbate ventricular electrical instability leading to arrhythmia clusters and electrical storm. METHODS: Two hundred and fourteen consecutive defibrillator recipients were followed-up during 3.3 +/- 2.2 years. Arrhythmia cluster was defined as the occurrence of three or more arrhythmic events triggering appropriate defibrillator therapies within 2 weeks. Time intervals between two clusters were calculated for each month and each season, and were compared using Kruskal-Wallis test and Wilcoxon-Mann-Whitney test with Bonferroni adjustment. RESULTS: During a follow-up of 698 patient years, 98 arrhythmia clusters were observed in 51 patients; clustering ventricular arrhythmias were associated with temporal variables; they occurred more frequently in the winter and spring months than during the summer and fall. Accordingly, the time intervals between two clusters were significantly shorter during winter and spring (median and 95% CI): winter 16 (5-19), spring 11.5 (7-25), summer 34.5 (15-55), fall 50.5 (19-65), P = 0.0041. CONCLUSION: There are important seasonal variations in the incidence of arrhythmia clusters in ICD recipients. Whether these variations are related to environmental factors, change in physical activity, or psychological factors requires further study.

Mycophenolate acid inhibits endothelial NAD(P)H oxidase activity and superoxide formation by a Rac1-dependent mechanism

Endothelial dysfunction precedes hypertension and atherosclerosis and predicts cardiac allograft vasculopathy and death in heart transplant recipients. Endothelial overproduction of reactive oxygen species, such as superoxide anions produced by NAD(P)H oxidase, induces endothelial dysfunction. Because immunosuppressive drugs have been associated with increased reactive oxygen species production and endothelial dysfunction, we sought to elucidate the underlying mechanisms. Reactive oxygen species, release of superoxide anions, and NAD(P)H oxidase activity were studied in human umbilical vein endothelial cells and in polymorphonuclear neutrophils. Gp91ds-tat was used to specifically block NAD(P)H oxidase. Transcriptional activation of different subunits of NAD(P)H oxidase was assessed by real-time RT-PCR. Rac1 subunit translocation and activation were studied by membrane fractionation and pull-down assays. Calcineurin inhibitors significantly increased endothelial superoxide anions production because of NAD(P)H oxidase, whereas mycophenolate acid (MPA) blocked it. MPA also attenuated the respiratory burst induced by neutrophil NAD(P)H oxidase. Because transcriptional activation of NAD(P)H oxidase was not affected, but addition of guanosine restored endothelial superoxide anions formation after MPA treatment, we speculate that the inhibitory effect of MPA was mediated by depletion of cellular guanosine triphosphate content. This prevented activation of Rac1 and, thus, of endothelial NAD(P)H oxidase. Because all heart transplant recipients are at risk for cardiac allograft vasculopathy development, these differential effects of immunosuppressants on endothelial oxidative stress should be considered in the choice of immunosuppressive drugs.

Diastolic dysfunction in human cardiac allografts is related with reduced SERCA2a gene expression

Previous studies demonstrated that impaired left ventricular (LV) relaxation in cardiac allografts limits exercise tolerance post-transplant despite preserved systolic ejection fraction (EF). This study tested in human cardiac allografts whether the isovolumic relaxation time (IVRT), which provides the basis for most of diastolic LV filling, relates with gene expression of regulatory proteins of calcium homeostasis or cardiac matrix proteins. Gene expression was studied in 31 heart transplant recipients (25 male, 6 female) 13-83 months post-transplant with LVEF >50%, LV end-diastolic pressure <20 mmHg, normal LV mass index and without allograft rejection or significant cardiac pathology. IVRT related with the other diastolic parameters e-wave velocity (r = -0.46; p = 0.01), e/a-wave ratio (r = -0.5; p < 0.01) but not with heart frequency (r = -0.16; p = 0.4). No relation of IVRT was observed for immunosuppression, mean rejection grade or other medication. IVRT was not related with gene expression of desmin, collagen I, phospholamban, the Na+-Ca2+ exchanger, the ryanodine receptor or interstitial fibrosis but correlated inversely with SERCA2a (r = -0.48; p = 0.02). Prolonged IVRT is associated with decreased SERCA2a expression in cardiac allografts without significant other pathology. Similar observations in non-transplanted patients with diastolic failure suggest that decreased SERCA2a expression is an important common pathomechanism.

Differential regulation of metzincins in experimental chronic renal allograft rejection: potential markers and novel therapeutic targets

Chronic renal allograft rejection is characterized by alterations in the extracellular matrix compartment and in the proliferation of various cell types. These features are controlled, in part by the metzincin superfamily of metallo-endopeptidases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinase (ADAM) and meprin. Therefore, we investigated the regulation of metzincins in the established Fisher to Lewis rat kidney transplant model. Studies were performed using frozen homogenates and paraffin sections of rat kidneys at day 0 (healthy controls) and during periods of chronic rejection at day +60 and day +100 following transplantation. The messenger RNA (mRNA) expression was examined by Affymetrix Rat Expression Array 230A GeneChip and by real-time Taqman polymerase chain reaction analyses. Protein expression was studied by zymography, Western blot analyses, and immunohistology. mRNA levels of MMPs (MMP-2/-11/-12/-14), of their inhibitors (tissue inhibitors of metalloproteinase (TIMP)-1/-2), ADAM-17 and transforming growth factor (TGF)-beta1 significantly increased during chronic renal allograft rejection. MMP-2 activity and immunohistological staining were augmented accordingly. The most important mRNA elevation was observed in the case of MMP-12. As expected, Western blot analyses also demonstrated increased production of MMP-12, MMP-14, and TIMP-2 (in the latter two cases as individual proteins and as complexes). In contrast, mRNA levels of MMP-9/-24 and meprin alpha/beta had decreased. Accordingly, MMP-9 protein levels and meprin alpha/beta synthesis and activity were downregulated significantly. Members of metzincin families (MMP, ADAM, and meprin) and of TIMPs are differentially regulated in chronic renal allograft rejection. Thus, an altered pattern of metzincins may represent novel diagnostic markers and possibly may provide novel targets for future therapeutic interventions.

Chronic rhinoviral infection in lung transplant recipients

RATIONALE: Lung transplant recipients are particularly at risk of complications from rhinovirus, the most frequent respiratory virus circulating in the community. OBJECTIVES: To determine whether lung transplant recipients can be chronically infected by rhinovirus and the potential clinical impact. METHODS: We first identified an index case, in which rhinovirus was isolated repeatedly, and conducted detailed molecular analysis to determine whether this was related to a unique strain or to re-infection episodes. Transbronchial biopsies were used to assess the presence of rhinovirus in the lung parenchyma. The incidence of chronic rhinoviral infections and potential clinical impact was assessed prospectively in a cohort of 68 lung transplant recipients during 19 mo by screening of bronchoalveolar lavages. MEASUREMENTS AND MAIN RESULTS: We describe 3 lung transplant recipients with graft dysfunctions in whom rhinovirus was identified by reverse transcriptase-polymerase chain reaction in upper and lower respiratory specimens over a 12-mo period. In two cases, rhinovirus was repeatedly isolated in culture. The persistence of a unique strain in each case was confirmed by sequence analysis of the 5'NCR and VP1 gene. In the index case, rhinovirus was detected in the lower respiratory parenchyma. In the cohort of lung transplant recipients, rhinoviral infections were documented in bronchoalveolar lavage specimens of 10 recipients, and 2 presented with a persistent infection. CONCLUSIONS: Rhinoviral infection can be persistent in lung transplant recipients with graft dysfunction, and the virus can be detected in the lung parenchyma. Given the potential clinical impact, chronic rhinoviral infection needs to be considered in lung transplant recipients.

Effect of cinacalcet cessation in renal transplant recipients with persistent hyperparathyroidism

BACKGROUND: Persistent hyperparathyroidism after renal transplantation affects bone and allografts. Cinacalcet, a calcimimetic, reduces serum calcium and PTH in renal transplant recipients with persistent hyperparathyroidism. Here, we address the question whether this effect of cinacalcet persists after withdrawal. METHODS: Therefore, cinacalcet was stopped after 12 months treatment in 10 stable renal transplant patients. Serum calcium, phosphate, PTH, creatinine and cystatin C were monitored for 3 months. RESULTS: Serum calcium, normalized in nine patients before cessation of cinacalcet (2.32 +/- 0.05mmol/l, mean +/- SEM), increased after 3 months of discontinuation by 0.17 +/- 0.04mmol/l, P < 0.05, but remained within the normal range in eight patients. Compared with the time point of cessation, PTH remained unchanged or decreased further after 3 months without therapy in six patients. Measurements of cystatin C suggested an improvement of the glomerular filtration rate after cessation in 9 out of 10 patients (1.55 +/- 0.09 vs 1.33 +/- 0.12 mg/l, P < 0.01). CONCLUSION: First, a beneficial effect of cinacalcet beyond the duration of a 12-month therapy appears to be present in some patients and second, the previously suspected influence of cinacalcet therapy on renal function is reversible. Thus, it is reasonable to consider a trial of cinacalcet cessation to identify these patients. The optimal time point for such a discontinuation is unknown. The present observations are preliminary. They clearly require a prospective randomized trial for definitive confirmation.