A.Z. Aliabadi

Development of Proteinuria After Switch to Sirolimus‐Based Immunosuppression in Long‐Term Cardiac Transplant Patients

Calcineurin‐inhibitor therapy can lead to renal dysfunction in heart transplantation patients. The novel immunosuppressive (IS) drug sirolmus (Srl) lacks nephrotoxic effects; however, proteinuria associated with Srl has been reported following renal transplantation. In cardiac transplantation, the incidence of proteinuria associated with Srl is unknown. In this study, long‐term cardiac transplant patients were switched from cyclosporine to Srl‐based IS. Concomitant IS consisted of mycophenolate mofetil ± steroids. Proteinuria increased significantly from a median of 0.13 g/day (range 0–5.7) preswitch to 0.23 g/day (0–9.88) at 24 months postswitch (p = 0.0024). Before the switch, 11.5% of patients had high‐grade proteinuria (>1.0 g/day); this increased to 22.9% postswitch (p = 0.006). ACE inhibitor and angiotensin‐releasing blocker (ARB) therapy reduced proteinuria development. Patients without proteinuria had increased renal function (median 42.5 vs. 64.1, p = 0.25), whereas patients who developed high‐grade proteinuria showed decreased renal function at the end of follow‐up (median 39.6 vs. 29.2, p = 0.125). Thus, proteinuria may develop in cardiac transplant patients after switch to Srl, which may have an adverse effect on renal function in these patients. Srl should be used with ACEi/ARB therapy and patients monitored for proteinuria and increased renal dysfunction.

Components of the interleukin-33/ST2 system are differentially expressed and regulated in human cardiac cells and in cells of the cardiac vasculature

Interleukin-33 (IL-33) is a recently described member of the IL-1 family of cytokines, which was identified as a ligand for the ST2 receptor. Components of the IL-33/ST2 system were shown to be expressed in normal and pressure overloaded human myocardium, and soluble ST2 (sST2) has emerged as a prognostic biomarker in myocardial infarction and heart failure. However, expression and regulation of IL-33 in human adult cardiac myocytes and fibroblasts was not tested before. In this study we found that primary human adult cardiac fibroblasts (HACF) and human adult cardiac myocytes (HACM) constitutively express nuclear IL-33 that is released during cell necrosis. Tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-1β significantly increased both IL-33 protein and IL-33 mRNA expression in HACF and HACM as well as in human coronary artery smooth muscle cells (HCASMC). The nuclear factor-κB (NF-κB) inhibitor dimethylfumarate inhibited TNF-α- and IL-1β-induced IL-33 production as well as nuclear translocation of p50 and p65 NF-κB subunits in these cells. Mitogen-activated protein/extracellular signal-regulated kinase inhibitor U0126 abrogated TNF-α-, IFN-γ-, and IL-1β-induced and Janus-activated kinase inhibitor I reduced IFN-γ-induced IL-33 production. We detected IL-33 mRNA in human myocardial tissue from patients undergoing heart transplantation (n = 27) where IL-33 mRNA levels statistically significant correlated with IFN-γ (r = 0.591, p = 0.001) and TNF-α (r = 0.408, p = 0.035) mRNA expression. Endothelial cells in human heart expressed IL-33 as well as ST2 protein. We also reveal that human cardiac and vascular cells have different distribution patterns of ST2 isoforms (sST2 and transmembrane ST2L) mRNA expression and produce different amounts of sST2 protein. Both human macrovascular (aortic and coronary artery) and heart microvascular endothelial cells express specific mRNA for both ST2 isoforms (ST2L and sST2) and are a source for sST2 protein, whereas cardiac myocytes, cardiac fibroblasts and vascular SMC express only minor amounts of ST2 mRNA and do not secrete detectable amounts of sST2 antigen. In accordance with the cellular distribution of ST2 receptor, human cardiac fibroblasts and myocytes as well as HCASMC did not respond to treatment with IL-33, as recombinant human IL-33 did not induce NF-κB p50 and p65 subunits nuclear translocation or increase IL-6, IL-8, and monocyte chemoattractant protein (MCP-1) level in HACF, HACM and HCASMC. In summary, we found that endothelial cells seem to be the source of sST2 and the target for IL-33 in the cardiovascular system. IL-33 is expressed in the nucleus of human adult cardiac fibroblasts and myocytes and released during necrosis. Proinflammatory cytokines TNF-α, IFN-γ and IL-1β increase IL-33 in these cells in vitro, and IL-33 mRNA levels correlated with TNF-α and IFN-γ mRNA expression in human myocardial tissue.

Calcineurin-inhibitor minimization protocols in heart transplantation

Cardiac transplantation has become an established method for end‐stage heart disease. A calcineurin‐inhibitor (CNI)‐based regimen is the cornerstone of immunosuppressive therapy after cardiac transplantation. CNIs have reduced acute rejection and infection and markedly increased survival of cardiac transplantation patients. However, the dose‐ and time‐dependent nephrotoxic effects of CNIs can limit long‐term survival, and chronic renal failure is a major cause of morbidity and mortality in long‐term cardiac transplant patients. Early experience on withdrawal of CNIs (and maintenance of patients on azathioprine and steroids) in patients, who developed chronic renal dysfunction, resulted in rejection episodes with, sometimes, fatal outcome. The introduction of newer immunosuppressive drugs, like thymoglobulin, anti CD‐25 monoclonal antibodies, mycophenolate mofetil, everolimus or sirolimus into clinical practice, has given transplant physicians new tools to adapt immunosuppression to patients’ needs. Changes of immunosuppressive protocols by using new drugs early and late after transplantation and simultaneous reduction or weaning of CNIs have become attractive options. The aim of this article is to review strategies to delay, reduce or prevent CNIs after cardiac transplantation as means to improve short‐ and long‐term outcome mainly by protecting renal function.

Detection of High-grade Stenoses With Multislice Computed Tomography in Heart Transplant Patients

BACKGROUND Post-transplant follow-up of heart transplant patients consists of repeated coronary angiography, which is associated with high costs, discomfort and risk. We sought to determine whether multislice computed tomography (MSCT) permits the exclusion or progression of coronary artery disease in heart transplant patients. METHODS MSCT scanning (Philips CT MX 8000 IDT) and invasive coronary angiography were performed on 66 consecutive heart transplant patients. One hundred milliliters of non-ionic iodinated contrast medium was applied for CT angiography. For MSCT analysis, coronary arteries and side branches with a diameter > or =1.5 mm were assessed for the presence of luminal narrowing of >70%. MSCT results were compared with those of quantitative coronary angiography analysis. RESULTS Ten patients (17%) had one significant stenosis, whereas 3 patients (5%) had 2-vessel disease and none had 3-vessel disease. MSCT was performed successfully on 60 patients enrolled in our analysis. Forty-two of 44 patients (95%) who were estimated to be fully evaluable for MSCT were correctly classified. On per-segment-based analysis, sensitivity, specificity and positive and negative predictive values were 59%, 94%, 91% and 99.43%, respectively. After exclusion of unevaluable segments, sensitivity and specificity increased to 71% and 99.86%, respectively. On per-patient-based analysis, sensitivity, specificity and positive and negative predictive values were 88%, 97%, 88% and 97%, respectively, in evaluable transplant recipients. CONCLUSIONS MSCT with its high specificity and high negative predictive value allows the exclusion of significant coronary artery vasculopathy in evaluable patients. From the clinical point of view, this might spare additional invasive coronary angiography in heart transplant patients.

Current strategies and future trends in immunosuppression after heart transplantation.

Purpose of reviewCurrent immunosuppressive drugs have provided excellent outcomes after heart transplantation. However, more patients suffer from long-term complications of these drugs. A series of prospective randomized trials has been conducted and has offered disparate results. This report reviews the challenges of immunosuppressive therapy during the past decade, describes recent reports and explores potential future trends in immunosuppressive protocols in heart transplantation. Recent findingsThe traditional combination of cyclosporine, azathioprine and steroids has been changed to tacrolimus (Tac) or cyclosporine in combination with mycophenolate mofetil (MMF) and steroids due to the results of several trials. The use of mammalian target of rapamycin inhibitors in combination with Tac or cyclosporine A has not shown a clear benefit compared with MMF. All different combinations have shown some positive effects counteracted by side-effects and negative synergism of combinations. Future protocols need to be adapted according to individual patients needs and risks. SummaryThe changing population of heart transplantation patients has become older and sicker. Immunosuppression strategies should be developed for each patient based on their risk for rejection and their risk for developing important complications of immunosuppressive therapy.

Safety and efficacy of statin therapy in patients switched from cyclosporine a to sirolimus after cardiac transplantation.

Introduction. Statins are an established therapy after cardiac transplantation. Sirolimus (Srl) has been used successfully in cardiac transplant patients. However, potential side effects are hyperlipidemia and interactions with statins. The aim of the study was to evaluate the safety and efficacy of statin therapy after switch to a Srl-based immunosuppression. Patients and Methods. Ninety-eight long-term patients were switched from Cyclosporine A to Srl. Also all patients received mycophenolate mofetil alone or mycophenolate mofetil plus steroid therapy. Reasons for switch were renal dysfunction, graftvasculopathy, or skin cancer. Patients were switched 7.8±4.7 years after transplant. Total observation period was 12 months before and after switch, respectively. Safety evaluation consisted of regular measurements of CPK and liver enzymes to evaluate the incidence myopathy and hepatoxicity. Efficacy analysis was performed by serial blood lipid assessments (low-density lipoprotein, high-density lipoprotein, total cholesterol, and triglycerides). Results. Forty-three percentage of patients received atorvastatin, 38% pravastatin, and 18% other drugs or therapy changes. Most lipid blood levels increased significantly after switch (cholesterol: 192.9±38.6 mg/dL vs. 221.8±49.2 mg/dL, P<0.0001; low-density lipoprotein: 108.0±35.6 mg/dL vs. 123.8±37.9 mg/dL, P<0.0001; and triglycerides: 178.3±88.2 mg/dL vs. 225.5±139.1 mg/dL, P<0.0001). Blood lipid levels after switch were not associated with statin type. Overall safety was acceptable, although incidence of myopathy doubled after switch (n=20 vs. 40; P<0.01). However, most cases were asymptomatic CPK elevations in the pravastatin group. Hepatotoxicity rate was 4% and only temporary. Conclusion. Statin therapy after switch from cyclosporine A to Srl in long-term cardiac transplant patients is safe. However, regular testing of blood lipids and CPK should be mandatory.

Induction therapy in heart transplantation: where are we now?

Although induction therapy has been used in heart transplantation for many years, its role has not been fully elucidated. Early safety concerns relating to OKT3 or intensive lymphocyte‐depleting regimens have largely been addressed by modern induction protocols using rabbit antithymocyte globulin (rATG [Thymoglobuline® or ATG‐Fresenius]) and interleukin‐2 receptor antagonist (IL‐2RA) agents, but although the number of randomized controlled studies has expanded there are still gaps in the evidence base. Rejection prophylaxis may be somewhat more effective with rATG than IL‐2RA agents, but this has not been proven conclusively. Administration of induction therapy to support delayed introduction of calcineurin inhibitors in patients at risk of renal dysfunction is relatively well documented and widely used. Increasingly, it is recognized that sensitized patients and individuals with primary graft function are suitable candidates for induction therapy, and the possibility that rATG may inhibit cardiac allograft vasculopathy is also of considerable interest. Until the question of whether rATG is associated with increased risk of infection, routine prophylaxis is advisable. IL‐2RA induction has an excellent safety profile. Dosing rATG according to lymphocyte count reduces cumulative dose without compromising efficacy. Further controlled trials are required to determine when and how to deploy induction most effectively following heart transplantation.

Immunosuppressive Therapy in Older Cardiac Transplant Patients

Cardiac transplantation has become an established intervention for end-stage heart disease. Clinical outcomes in older cardiac transplant patients have improved over the last decade and are almost similar to those in younger patients. Nevertheless, morbidity and mortality due to infections, cancer and chronic allograft vasculopathy remain problematic. On the other hand, older transplant patients seem to have lower incidences of acute rejection episodes than younger patients. Conventional immunosuppression with calcineurin-inhibiting drugs, azathioprine and corticosteroids is responsible for a number of adverse effects. Although these adverse effects can also be seen in younger patients, tolerance to these agents seems to decrease with increasing age. In particular, diabetes mellitus, osteoporosis and chronic renal insufficiency are associated with higher morbidity and mortality in older cardiac transplant patients. As the elderly become an ever-increasing segment of the cardiac transplant population, new and innovative immunosuppressive strategies will have to be developed and applied.Currently, the availability of new immunosuppressive drugs means more individualised immunosuppressive protocols can be used. New antibodies for induction therapy, a choice between ciclosporin and tacrolimus, and the advent of mycophenolate mofetil as well as proliferation signal inhibitors (everolimus, sirolimus) have changed immunosuppressive protocols dramatically. Therefore, a generalised protocol for all patients has been replaced by individualised immunosuppression depending on the patient group. Moreover, protocols can be modified during follow-up depending on the individual patient’s requirements and problems. Hypertension and hyperlipidaemia could be influenced by the selection of tacrolimus over ciclosporin, and weaning of corticosteroids might have a positive impact on osteoporosis or diabetes. There is also no clear evidence that tacrolimus is associated with a higher risk for new onset of diabetes. Chronic renal insufficiency can be managed with calcineurin inhibitor-free immunosuppression consisting of mycophenolate mofetil and proliferation signal inhibitors. Both everolimus and sirolimus also seem to have a protective effect against the onset of graft vasculopathy and some sorts of cancer after cardiac transplantation. As a general rule, however, older cardiac transplant patients should be treated with lower doses and fewer immunosuppressive drugs to avoid over-immunosuppression.

Donor Serum SMARCAL1 Concentrations Predict Primary Graft Dysfunction in Cardiac Transplantation

Background— Primary graft dysfunction (PGD) is a life-threatening complication in cardiac transplantation. A sensitive, specific, and easily measurable predictor in donors could facilitate PGD prevention. Methods and Results— SMARCAL1 is a matrix-associated regulator of chromatin with helicase and ATPase activities, and its serum concentrations were significantly increased in a targeted protein array in donors whose grafts developed PGD. Therefore, this study analyzed SMARCAL1 serum concentrations by ELISA in 336 heart donors before and after aortic cross-clamping (ACC) and in recipients at 10, 30, and 60 minutes reperfusion. Demographic and hemodynamic parameters of donors and recipients as well as transplant procedure characteristics were documented. PGD (n=68) was defined as ventricular dilation and hypocontractility associated with systolic blood pressure <90 mm Hg, pulmonary capillary wedge pressure >20 mm Hg, and decreased mixed venous oxygen saturation necessitating mechanical circulatory support. SMARCAL1 serum protein concentration was significantly increased only before and after ACC in donors (P<0.0001) whose grafts developed PGD compared to those who did not. In receiver operating characteristic curve analysis, SMARCAL1 serum concentration at a cut-off level of ≥1.25 ng/mL before ACC in donors predicted PGD (P<0.0001, AUC=0.988, OR=17.050, 95% CI=5.200 to 55.901) with 96% sensitivity and 88% specificity. SMARCAL1 serum concentrations <1.25 ng/mL in donors before ACC resulted in 97% PGD-free outcome and SMARCAL1 concentrations ≥1.25 resulted in 83% PGD occurrence. Conclusions— Donor serum SMARCAL1 may serve as a specific, sensitive, and noninvasive predictive marker in the assessment of cardiac graft quality.

Serum Matrix Metalloprotease‐1 and Vascular Endothelial Growth Factor–A Predict Cardiac Allograft Rejection

Cardiac allograft rejection is currently diagnosed from endomyocardial biopsies (EMB) that are invasive and impractical to repeat. A serological marker could facilitate rejection monitoring and minimize EMB‐associated risks. We investigated the relation of serum matrix metalloprotease (MMP)‐1 and vascular endothelial growth factor (VEGF)‐A concentrations to cardiac allograft rejection, using 1176 EMBs and serum samples obtained from 208 recipients. Acute cellular rejection was diagnosed in 186 EMBs. Mean week 1 and week 2 serum MMP‐1 concentrations predicted rejection (p = 0.001, AUC = 0.80). At the optimal cut‐off level of ≥7.5 ng/mL, MMP‐1 predicted rejection with 82% sensitivity and 72% specificity. Initial serum MMP‐1 <5.3 ng/mL (lowest quartile) was associated with rejection‐free outcome in 80% of patients. Both MMP‐1 (p < 0.001, AUC = 0.67–0.75) and VEGF‐A (p < 0.01, AUC = 0.62–0.67) predicted rejection on the next EMB, while rejection at EMB was identified only by VEGF‐A (p < 0.02, AUC = 0.70–0.77). Patients receiving combined cyclosporine‐A and everolimus had the lowest serum MMP‐1 concentrations. While serum MMP‐1 predicts rejection‐free outcome and VEGF‐A identifies rejection on EMB, both markers predict rejection in follow‐up of cardiac transplant recipients. Combination of serum MMP‐1 and VEGF‐A concentration may be a noninvasive prognostic marker of cardiac allograft rejection, and could have important implications for choice of surveillance and immunosuppression protocols.