心脏移植术后的免疫抑制治疗和免疫监测

心脏移植是治疗终末期心脏疾病的有效手段。以钙调磷酸酶抑制剂(CsA或FK506)为基础的免疫抑制治疗是心脏移植术后最常用的免疫抑制方案,许多心脏移植受者在移植前或/和移植后同时使用单克隆抗体进行诱导治疗。雷帕霉素和Everolimus等新型免疫抑制剂在有效抑制急性排斥反应的同时还可预防移植物心血管病变,显示出较好的应用前景。应用免疫学指标、心肌标记物和其它血清标记物等相对无创的指标预测和估计排斥反应的发生及其程度,有助于尽早发现和控制移植排斥反应,以提高心脏移植的效果。     

Successful conversion to rapamycin for calcineurin inhibitor-related neurotoxicity following liver transplantation

INTRODUCTION: Neurotoxicity is a well-recognized side effect of calcineurin inhibitors. Rapamycin is considered to be significantly less neurotoxic than calcineurin inhibitors (CNIs). The aim of this study was to retrospectively analyze a group of post-liver transplant patients who had been converted to rapamycin because of CNI-related neurotoxicity. PATIENTS AND METHODS: Orthotopic liver transplantation (OLT) was performed in 56 consecutive patients between April 1, 2003, and August 15, 2004. Immunosuppression was administered with tacrolimus, mycophenolic acid, and corticosteroids. RESULTS: Seven patients were converted to rapamycin due to new-onset neurotoxicity or exacerbation of previous neurological symptoms secondary to CNI. None of the patients had toxic levels tacrolimus (>15 ng/mL) at the time of symptoms, which persisted despite reduction of CNI dose. The indications for conversion were: (1) peripheral neuropathy; (2) seizure; (3) metabolic encephalopathy; and (4) central pontine myelinolysis. All patients showed improvement or resolution of their neurological symptoms after conversion to rapamycin. Two patients died, the first due to a hypoxic event and the second due to central pontine myelinolysis with limited improvement and a family decision to withdraw care. There were no complications directly attributed to rapamycin. Specifically, there were no thrombotic events, wound complications, or biliary leaks. Three patients had a rejection episode that was successfully treated with pulse corticosteroids and low-dose tacrolimus (levels < 5 ng/mL). CONCLUSIONS: Rapamycin can be safely used in OLT recipients with severe neurological symptoms ascribed to or exacerbated by CNIs. Rapamycin monotherapy may be inadequate to control rejection early after transplantation. Rapamycin can be combined with low doses of CNI to prevent rejection.     

Thrombotic Micro‐Angiopathy with Sirolimus‐Based Immunosuppression: Potentiation of Calcineurin‐Inhibitor‐Induced Endothelial Damage?

Thrombotic microangiopathy is a rare but important finding in the context of organ transplantation. Acute renal insufficiency in the setting of hemolysis and thrombocytopenia, a triad that constitutes 'hemolytic uremic syndrome', can be associated with, or triggered by, conditions such as verocytotoxin-producing Escherichia coli, viral infections, malignant hypertension, scleroderma, allograft rejection, lupus erythematosus, pregnancy, and medications including mitomycin C, calcineurin inhibitors, and oral contraceptives. After renal transplantation, it can occur, as either a de novo episode, or recurrent disease. Calcineurin inhibitors have long been associated with post-transplantation thrombotic microangiopathy. Sirolimus has been used as a primary immunosuppressant in patients transplanted with a history of earlier hemolytic-uremic syndrome, and also as rescue therapy in patients with calcineurin-inhibitor-associated thrombotic microangiopathy. We describe four cases where there was significant thrombotic microangiopathy in the context of contemporaneous or contiguous calcineurin inhibitor and sirolimus usage. As the intrarenal cyclosporin concentration is thought to be significantly elevated when cyclosporin and sirolimus are used together, this may explain these findings, and mandates caution in their co-administration.     

Rapamycin in lung transplantation: preliminary results

INTRODUCTION: Rapamycin is a potent immunosuppressive agent with a different mechanism of action and different adverse effects from those of calcineurin inhibitors (CNIs). OBJECTIVE: To analyze our experience with rapamycin in patients undergoing lung transplantation and heart-lung transplantation in our center. PATIENTS AND METHODS: Patients were treated with rapamycin when showing chronic rejection and/or toxicity associated with the CNI after lung transplantation or heartlung transplantation. Patients with chronic rejection were administered rapamycin in combination with CNIs, whereas the CNIs were eliminated in patients with toxicity. RESULTS: Since October 2001, 7 patients (4 women), of mean age 45+/-15 years, received treatment with rapamycin (heart-lung transplantation, 2 cases; lung transplantation, 5 cases). The indications were chronic rejection in 4 patients and CMIs toxicity in 3 patients (kidney failure in 2 cases and optic neuropathy in 1 case). Pulmonary function stabilization was observed in 3 of 4 patients receiving rapamycin for chronic rejection. In the 3 patients with CNIs toxicity elimination of these drugs did not result in pulmonary functional deterioration. Patients with kidney failure showed an improvement in creatinine levels; visual acuity improved in the patient with optic neuropathy. We observed 2 infectious complications (pneumococcal pneumonia and pulmonary aspergillosis), which resolved with treatment. CONCLUSION: Rapamycin is an alternative for lung-transplant recipients who develop chronic rejection and/or CNIs toxicity.     

The benefits of new immunosuppressive treatments in adult kidney transplantation

NEW KNOWLEDGE: Over the last few years, improved knowledge of the immunological mechanisms underlying transplant rejection have resulted in the development of new immunosuppressive agents capable of selectively blocking various steps of the immune response. NEW MOLECULES: The review focuses on new immunosuppressive drugs that have been developed for clinical use in renal transplantation and mechanism of action, advantages and side effects will be discussed for each of them. Neoral is a cyclosporin microemulsion, characterized by more consistent absorption. Tacrolimus shares with cyclosporin an ability to inhibit calcineurin but presents some differences. Mycophenolate mofetyl selectively inhibits purine synthesis and lymphocyte proliferation; it is easy to use and has been found effective in large clinical trials. Rapamycin and RAD are two related molecules that inhibit signal transduction by cytokines to T-cells, their use in transplant therapy remains to be determined. Anti-interleukin-2 receptor antibodies are also reviewed; they are easy to use and have been found effective. NEW STRATEGIES: These new immunosuppressive drugs provide new approaches in transplant therapy to improve their efficacy and safety.     

Calcineurin nephrotoxicity

Calcineurin inhibitors, cyclosporine and tacrolimus, have improved allograft survival in solid organ transplantation. Indeed, they have reduced the incidence of acute rejection episodes of cadaveric allograft recipients. Although marked progression has been made in initial survival rates, long-term kidney graft survival has yet to show such encouraging results. Chronic allograft dysfunction is the major hindrance to long-term graft survival and many components contribute to this entity, both immunologic and nonimmunologic. Chronic calcineurin nephrotoxicity is a major factor in chronic allograft dysfunction. This review will highlight the current understanding and management of calcineurin nephrotoxicity in kidney transplantation.     

Immunosuppression and Results in Renal Transplantation

Keeping a balance between the effective prevention of rejection and the side effects of immunosuppressants is a key point for long-term renal transplantation success. Today antibody induction (either basiliximab or depleting polyclonal antibodies for high-risk patients) together with an initial combination therapy of calcineurin inhibitor (CNI), mycophenolate, and steroids is recommended and results in excellent early outcomes. Yet despite the significant decrease in the incidence of acute rejection, long-term graft loss has remained rather constant over the last 25 yr. Thus new immunosuppressive combination strategies, avoiding or minimising CNIs, have been a goal in many randomised controlled trials during the last decade. Although it is too early to reach conclusions about the success of these strategies, some results are rather encouraging, in particular strategies including novel biotherapies like belatacept. This review updates the current knowledge and indications of modern immunosuppressants in the setting of renal transplantation and offers an overview of the regimen strategies available to minimise long-term side effects and prolong the survival of both patients and allografts.Patient summary Modern immunosuppression strategies with calcineurin inhibitors (CNIs) and mycophenolate have reduced incidence of acute rejection but failed to improve long-term renal outcome. Efforts to minimise or replace CNIs have led to encouraging results, but long-term follow-up and integration of new drugs in these strategies are required to really improve long-term results after renal transplantation.     

Tacrolimus to Belatacept Conversion Following Hand Transplantation: A Case Report

Vascularized composite allotransplantation (VCA) has emerged as a viable limb replacement strategy for selected patients with upper limb amputation. However, allograft rejection has been seen in essentially all reported VCA recipients indicating a requirement for substantial immunosuppressive therapy. Calcineurin inhibitors have served as the centerpiece agent in all reported cases, and CNI‐associated complications associated with the broad therapeutic effects and side effects of calcineurin inhibitors have been similarly common. Recently, belatacept has been approved as a calcineurin inhibitor replacement in kidney transplantation, but to date, its use in VCA has not been reported. Herein, we report on the case of a hand transplant recipient who developed recurrent acute rejection with alloantibody formation and concomitant calcineurin inhibitor nephrotoxicity, all of which resolved upon conversion from a maintenance regimen of tacrolimus, mycophenolate mofetil and steroids to belatacept and sirolimus. This case indicates that belatacept may be a reasonable maintenance immunosuppressive alternative for use in VCA, providing sufficient prophylaxis from rejection with a reduced side effect profile, the latter being particularly relevant for nonlife threatening conditions typically treated by VCA.     

Abatacept as rescue immunosuppression after calcineurin inhibitor treatment failure in renal transplantation

A majority of kidney transplant recipients receive calcineurin inhibitor‐based immunosuppression. However, some do not tolerate calcineurin inhibitors and require other immunosuppressive strategies. Until recently, alternative approaches have been associated with inferior outcomes, but recent methods have effectively utilized belatacept in calcineurin inhibitor‐intolerant patients. Though promising, belatacept uptake has been limited by higher acute rejection rates, unavailability due to production shortages, and logistical challenges as a result of intravenous infusion requirements. Interestingly, its predecessor abatacept is clinically available in subcutaneous formulation to treat autoimmune disorders but has not been used in clinical transplantation. Here we report on a series of 9 calcineurin inhibitor‐intolerant transplant recipients converted to abatacept early after transplant as rescue immunosuppression during periods of belatacept unavailability. Retrospective review revealed successful allograft salvage and 100% patient and graft survival (median 115 months) after conversion to abatacept. Patients received abatacept for a median duration of 82 months with stable, long‐term renal allograft function, a single cellular rejection episode, and no clinically apparent protective immunity concerns. Hence our findings suggest that future clinical studies utilizing abatacept either de novo or as conversion therapy in transplant recipients should be considered.     

Individualizing early use of sirolimus in renal transplantation

One of the main goals in the current care of kidney transplant recipients is to extend long-term graft survival. Efficacious immunosuppressive agents devoid of nephrotoxicity are needed. In human clinical transplantation, sirolimus combined with other immunosuppressive drugs has proven to be a powerful immunosuppressant capable of preventing acute graft rejection, as well as of improving renal function, renal histology, and graft survival when compared with immunosuppressive regimens that include calcineurin inhibitors. The valuable experience gained through many clinical studies allows clinicians to plan sirolimus use. We present a review of the clinical experience and literature review on the use of sirolimus in the first 12 months posttransplantation.     

Short-term therapy with anti-ICAM-1 monoclonal antibody induced long-term liver allograft survival in nonhuman primates

Tolerance induction remains challenging following liver transplantation and the long-term use of immunosuppressants, especially calcineurin inhibitors, leads to serious complications. We aimed to test an alternative immunosuppressant, a chimeric anti-ICAM-1 monoclonal antibody, MD-3, for improving the outcomes of liver transplantation. We used a rhesus macaque liver transplantation model and monkeys were divided into three groups: no immunosuppression (n = 2), conventional immunosuppression (n = 4), and MD-3 (n = 5). Without immunosuppression, liver allografts failed within a week by acute rejection. Sixteen-week-long conventional immunosuppression that consisted of prednisolone, tacrolimus, and an mTOR inhibitor prolonged liver allograft survival; however, recipients died of acute T cell–mediated rejection (day 52), chronic rejection (days 62 and 66), or adverse effects of mTOR inhibitor (day 32). In contrast, 12-week-long MD-3 therapy with transient conventional immunosuppression in the MD-3 group significantly prolonged the survival of liver allograft recipients (5, 96, 216, 412, 730 days; p = .0483). MD-3 effectively suppressed intragraft inflammatory cell infiltration, anti-donor T cell responses, and donor-specific antibody with intact anti-cytomegalovirus antibody responses. However, this regimen ended in chronic rejection. In conclusion, short-term therapy with MD-3 markedly improved liver allograft survival to 2 years without maintenance of immunosuppressant. MD-3 is therefore a promising immune-modulating agent for liver transplantation.     

Conversion from calcineurin inhibitor–based immunosuppression to mammalian target of rapamycin inhibitors or belatacept in renal transplant recipients

The calcineurin inhibitors (CNIs) remain the standard of care for maintenance immunosuppression following renal transplantation. CNIs have demonstrated their effectiveness in reducing acute cellular rejection; however, some evidence suggests that these compounds negatively affect native renal function and are associated with allograft injury in renal transplant recipients. CNIs have also been linked with hypertension, new‐onset diabetes after transplantation, tremor, and thrombotic microangiopathy, which have significant consequences for long‐term allograft function and patient health overall. Thus, converting patients to a non‐CNI‐based regimen may improve renal function and also provide extrarenal benefits. A number of studies have been conducted that explore CNI conversion strategies in renal transplant recipients in an effort to improve long‐term allograft function and survival. These include converting to alternative, non‐nephrotoxic, maintenance immunosuppressants, such as the mammalian target of rapamycin inhibitors (sirolimus and everolimus) and the costimulation blocker belatacept. In this review of literature, evidence for the potential renal and extrarenal benefits of conversion to these non‐CNI‐based regimens is evaluated. Clinical challenges, including the adverse event profiles of non‐CNI‐based regimens and the selection of candidates for conversion, are also examined.     

Mammalian Target of Rapamycin Inhibitors Vs Calcineurin Inhibitors in Chronic Graft Rejection After Lung Transplantation: A Systematic Review and Meta‐Analysis

BackgroundThe number of lung transplantations has been rising constantly. However, use of this therapeutic resource is limited by several issues that are difficult to resolve, such as chronic graft rejection and complications secondary to immunosuppression.MethodsThis systematic review compared mammalian target of rapamycin (mTOR) inhibitor immunosuppression associated with low-dose calcineurin inhibitors with isolated calcineurin inhibitor immunosuppression on the new-onset chronic rejection development and mortality 12 months after lung transplantation. Three controlled randomized clinical trials (SHITRIT, NOCTET, and 4EVERLUNG) were selected from electronic databases.ResultsMeta-analysis of the data at 12 months postintervention showed that only 4EVERLUNG assessed chronic graft rejection, with a higher incidence in the control group; however, the difference was not statistically significant (P = .197). Significant data were related to an increase in the number of adverse events (P = .0064) and improved renal function (P < .0001) in the mTOR inhibitor-based scheme. The other outcomes indicated a trend toward greater risk of death and acute graft rejection with the use of mTORs.ConclusionsThe researchers suggest considering the use of mTOR inhibitors, whose greatest benefit is felt by patients with renal dysfunction, in association with the use of calcineurin inhibitors, because of the imminent risk of death among patients with renal failure.     

Rapamycin Promotes Podocyte Migration Through the Up-regulation of Urokinase Receptor

Conversion to rapamycin from calcineurin inhibitors may contribute to improvement of graft function in kidney transplant recipients, especially in patients with calcineurin inhibitor–related nephrotoxicity. The conversion from calcineurin inhibitors to rapamycin in kidney transplant recipients has been associated with a higher incidence of proteinuria. It could be explained by possible hemodynamic changes due to withdrawal of calcineurin inhibitors. Podocyte damage occurs commonly in rapamycin-related proteinuria. The vascular endothelial growth factor system has been suggested to be implicated in mammalian target of rapamycin inhibitor–associated proteinuria. However, induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein. In this study, we assessed the role of uPAR in primary cultured podocytes with rapamycin treatment. Our results indicate that 24-hour rapamycin treatment promotes podocyte migration on the wound scratch assay in a dose-dependent manner. Rapamycin treatment for 2 days does not increase the apoptosis of podocytes or affect the podocyte cell viability and morphology. The up-regulation of uPAR in podocytes was confirmed by immunofluorescence staining, real-time polymerase chain reaction (1.8 ± 0.3–fold increase of relative quantification; P < .01) and Western blot analysis. Rapamycin treatment also causes the activation of FAK and ILK in a dose-dependent manner. In summary, rapamycin could promote podocyte migration through the up-regulation of uPAR. This finding provides a new mechanism of rapamycin-associated proteinuria. It also suggests that pharmacologic inhibition of uPAR signaling cascade may have therapeutic potential in the setting of rapamycin-related proteinuria.     

Sirolimus: its role in nephrology

Sirolimus (Rapamycin, Wyeth Pharmaceuticals Australia Pty Ltd, Baulkham Hills, NSW, Australia) (SRL) has received increasing attention as an immunosuppressant in renal and other solid organ transplantation. Sirolimus is the first marketed agent in a new class of drugs with a novel mechanism of action. Sirolimus binds, like tacrolimus, to a member of the FK binding protein (FKBP) family. The SRL/FKBP complex binds to the protein kinase mTOR. Binding to mTOR blocks activation of signal transduction pathways causing arrest of the cell cycle in the G1 phase. It is now known that mTOR is a central regulator of cell growth and proliferation. The immunosuppressive properties of SRL are due primarily to blockade of interleukin-2 (IL-2)-induced proliferation of T cells. There is still much to be learnt about how best to use the drug. The key advantage over the current choice of immunosuppressive agents is the ability to preserve renal function and pathology while producing excellent rejection-free, graft survival rates. Thus, SRL may find its pivotal role as a calcineurin inhibitors replacement in patients whose grafts are affected by chronic allograft nephropathy. A second major driver for use may prove to be the impact of SRL on cancer incidence and prognosis. Studies still need to be performed to evaluate the best timing for commencement of SRL and the optimal dosage to minimize side-effects.     

Immunosuppression Based on Everolimus in Liver Transplant Recipients With Severe Early Post-transplantation Neurotoxicity

The immunosuppressive management of liver transplant recipients suffering early calcineurin inhibitor–induced neurotoxicity is a challenge in daily clinical practice. We have assessed the use of everolimus as the main immunosuppressant in patients presenting severe neurotoxicity in the early post-transplantation period. From October 1988 to October 2012, 10 patients in our center received everolimus because of severe neurotoxicity in the 1st 3 months after transplantation. We analyzed several variables associated with this treatment, including patient characteristics, time from liver transplantation to conversion to everolimus, immunosuppression regimens before and after conversion, treatment efficacy, adverse events, and discontinuation after conversion. Median follow-up after conversion to everolimus was 27 months (range, 1–63 mo). Neurotoxic events were: akinetic mutism in 4 patients, repeated convulsions in 3, cerebrovascular accident in 1, Guillain-Barré syndrome in 1, and disabling tremor in 1. Treatment with calcineurin inhibitors was discontinued in all patients. Post-conversion regimens consisted of everolimus plus mycophenolate mofetil (MMF) plus steroids in 7 patients, everolimus plus MMF in 1, everolimus plus steroids in 1, and everolimus alone in 1. Liver function was maintained for ≥1 month in all patients except 1, who presented a severe rejection that was treated with steroid bolus and Neoral cyclosporine. Neurologic function was fully recovered in 8 patients. In 1 patient with akinetic mutism and another with convulsions, tacrolimus was reintroduced at 2 months and 1 month, respectively, after resolution of the neurotoxic event. Everolimus is feasible and effective as the main immunosuppressant in patients suffering severe neurotoxicity during the 1st 3 months after transplantation. It allows neurologic function to be recovered while maintaining adequate liver function.     

Carpe diem—Time to transition from empiric to precision medicine in kidney transplantation

The current immunosuppressive pipeline in kidney transplantation is limited. In part, this is due to excellent one‐year allograft outcomes with the current standard of care (ie, calcineurin inhibitor in combination with anti‐proliferative agents). Despite this success, a recent Federal government–sponsored systematic review has identified gaps/limits in the evidence of what constitutes optimal calcineurin inhibitor use in the short‐ and long‐term. Moreover, recent empiric approaches to minimize/withdraw/convert from calcineurin inhibitors have come with the price of increased alloreactivity. As the time horizon to replace calcineurin inhibitors on a global scale may be distant, the transplant community should seize the opportunity to develop ways to personalize calcineurin inhibitor immunosuppression to the individual—transitioning from empiricism to precision. The authors argue in this viewpoint that the path to precision will require measures capable of detecting subclinical alloreactivity to define adequacy of immunosuppression, as well as novel genetic analytics to accurately define alloimmune risk at the individual level—both approaches will require validation in clinical trials.

     

Chronic allograft nephropathy: pathogenesis and management of an important posttransplant complication

Chronic allograft nephropathy is a devastating complication of kidney transplantation that is responsible for a significant proportion of graft loss. This complication is characterized by a progressive decline in kidney function, which is not attributable to a specific cause. Many risk factors exist for the development of chronic allograft nephropathy, including donor-, recipient-, and transplant-related factors (eg, use of calcineurin inhibitors and acute rejection episodes), as well as comorbid conditions such as hypertension and hyperlipidemia. There is no definitive treatment for this complication; management has focused on minimization or withdrawal of calcineurin inhibitors in conjunction with addition of sirolimus or mycophenolate mofetil. Alterations in the immunosuppressive regimen must be done cautiously, as precipitating acute rejection will cause further damage to the allograft. Optimal control of blood pressure, particularly with the use of agents such as angiotensin II receptor blockers, in conjunction with management of dyslipidemia may be effective concurrent therapies in patients with chronic allograft nephropathy.     

Sirolimus as the main immunosuppressant in the early postoperative period following liver transplantation: a report of six cases and review of the literature

The use of sirolimus as the main immunosuppressant in a calcineurin inhibitor-free regimen in the early postoperative period of liver transplantation (LT), when the incidence of rejection is the highest, has seldom been reported. We report six patients who received sirolimus in association with steroids only, at a median time of 10 days after LT (range 3-23). Tacrolimus, initially given as the standard immunosuppressant, was discontinued because of nephrotoxicity in three of these patients and neurotoxicity in the other three. Resolution of the neurological symptoms was observed in all cases and a marked improvement of the renal function in two of three patients. Two patients died, one of sepsis and the other of recurrent hepatitis C virus hepatitis, after 47 and 143 days respectively. Three patients developed acute rejection which responded to intravenous steroids. In this cohort of patients, the use of sirolimus appeared safe and provided an adequate prophylaxis against rejection, even though the drug was administered in the immediate postoperative period after LT.