Calcineurin inhibitors in renal transplantation: what is the best option?

Immunosuppressive Therapy-Related Cardiovascular Risk Factors in Renal Transplantation: A Narrative Review

BACKGROUND

Kidney transplantation is the best treatment for patients with chronic renal failure, capable of improving life expectancy and the risk of death from all causes, which, however, remains higher than in the general population. The leading cause of death in transplant patients is cardiovascular events, burdened by a significant impact brought about by anti-rejection therapy. Experimental and clinical studies to date show that in kidney transplant recipients, traditional cardiovascular risk factors (hypertension, diabetes, dyslipidemia, obesity, tobacco, etc.) may be exacerbated or worsened by the dysmetabolic effects of immunosuppressive drugs, which may also result in additional risk factors such as proteinuria, anemia, and arterial stiffness. The aim of this review was to provide an in-depth evaluation of the effect of immunosuppressive treatments on cardiovascular risk factors.

SUMMARY

We have investigated and described the main cardiovascular risk factors related to immunosuppressive drugs. We searched for relevant scientific articles in medicine, transplant, cardiologic, and nephrological journals in major medical science libraries.

KEY MESSAGES

Immunosuppressive drugs allow graft survival and successful bunking of the transplant; however, they are not without significant side effects and should always be prescribed weighing the risk/benefit ratio and the individual patient's therapeutic needs.

Treatment Switches, Patterns, and Outcomes in Adult and Pediatric Patients Undergoing Kidney Transplantation Between 2000 and 2019: A Retrospective United States Claims Database Study

BACKGROUND

Immunosuppressive regimens are imperative for improving patient and graft survival following kidney transplantation in patients with kidney failure. However, real-world evidence regarding treatments and outcomes in these patients is scarce. We sought to describe the treatment switches (assessed by line of treatment [LOT]), patterns, and outcomes in patients who underwent kidney transplantation in the United States.

METHODS

This retrospective cohort study used claims data from the Optum Research Database in the United States. Adult and pediatric patients undergoing a kidney transplantation between January 1, 2000, and June 30, 2019, who had ≥1 year of baseline and follow-up visits and continuous enrollment in the Optum Research Database, were included.

RESULTS

Data from 7159 patients (6833, adult; 326, pediatric) were included. The mean age for adult and pediatric patients was 51.4 ± 12.8 years and 10.4 ± 5.1 years, respectively. The mean number of LOTs in patients with ≥1 LOT (n = 7004) was 4.1 ± 2.6 LOTs. Tacrolimus, antiproliferative agents, and prednisone were the most frequently prescribed immunosuppressants. No strong correlations were identified between switching from LOT1 to LOT2 and potential predictors of treatment switches. The proportion of patients who did not experience graft loss gradually decreased between month 3 and month 120 (72%-36%), driven by return to dialysis (66%-18%). A slower decrease was observed for graft rejection (98%-84%), retransplantation (98%-93%), and graft removal (98%-92%).

CONCLUSIONS

We described treatment switches, patterns, and outcomes in patients who underwent kidney transplantation in the United States. Future analytical studies are needed to test hypotheses derived from these observations.

Prenatal Exposition to Different Immunosuppressive Protocols Results in Vacuolar Degeneration of Hepatocytes

Immunosuppressive drugs are essential for transplant recipients, since they prolong proper function of graft; however, they affect the morphology and function of organs, including liver. One commonly observed alteration in hepatocytes is vacuolar degeneration. Numerous medications are contraindicated in pregnancy and breastfeeding, mostly due to a lack of data concerning their advert effects. The aim of the current study was to compare the effects of prenatal exposition to different protocols of immunosuppressants on vacuolar degeneration in the hepatocytes of livers of rats. Thirty-two livers of rats with usage of digital analysis of the images were examined. Area, perimeter, axis length, eccentricity and circularity regarding vacuolar degeneration were analysed. The most prominent vacuolar degeneration in hepatocytes in the aspects of presence, area and perimeter was observed in rats exposed to tacrolimus, mycophenolate mofetil and glucocorticoids, and cyclosporine A, everolimus with glucocorticoids.This is the first study that demonstrates the results of the influence of multidrug immnunosuppression distributed in utero on the hepatic tissue of offspring.

Nuclear factor of activated T-cells (NFAT) regulation of IL-1β-induced retinal vascular inflammation

Chronic low-grade retinal inflammation is an essential contributor to the pathogenesis of diabetic retinopathy (DR). It is characterized by increased retinal cell expression and secretion of a variety of inflammatory cytokines; among these, IL-1β has the reputation of being a major driver of cytokine-induced inflammation. IL-1β and other cytokines drive inflammatory changes that cause damage to retinal cells, leading to the hallmark vascular lesions of DR; these include increased leukocyte adherence, vascular permeability, and capillary cell death. Nuclear factor of activated T-cells (NFAT) is a transcriptional regulator of inflammatory cytokines and adhesion molecules and is expressed in retinal cells. Consequently, it may influence multiple pathogenic steps early in DR. We investigated the NFAT-dependency of IL-1β-induced inflammation in human Müller cells (hMC) and human retinal microvascular endothelial cells (hRMEC). Our results show that an NFAT inhibitor, Inhibitor of NFAT-Calcineurin Association-6 (INCA-6), decreased IL-1β-induced expression of IL-1β and TNFα in hMC, while having no effect on VEGF, CCL2, or CCL5 expression. We also demonstrate that INCA-6 attenuated IL-1β-induced increases of IL-1β, TNFα, IL-6, CCL2, and CCL5 (inflammatory cytokines and chemokines), and ICAM-1 and E-selectin (leukocyte adhesion molecules) expression in hRMEC. INCA-6 similarly inhibited IL-1β-induced increases in leukocyte adhesion in both hRMEC monolayers in vitro and an acute model of retinal inflammation in vivo. Finally, INCA-6 rescued IL-1β-induced permeability in both hRMEC monolayers in vitro and an acute model of retinal inflammation in vivo. Taken together, these data demonstrate the potential of NFAT inhibition to mitigate retinal inflammation secondary to diabetes.

FK506-loaded PLGA nanoparticles improve long-term survival of a vascularized composite allograft in a murine model

Background

The side effects of life-long administration of FK506 limit the clinical practice of vascularized composite allografts (VCAs). This study aimed to evaluate the feasibility of FK506-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles (FK506 NPs) for prolonging the long-term survival of VCAs and reducing the side effects of FK506.

Methods

PLGA nanoparticles loaded with FK506 were prepared by the solvent evaporation method. The characterization of FK506 NPs was evaluated by electron microscopy. To confirm the function and safety of FK506 NPs, these particles were administrated into rats by intraperitoneal injection. The survival time of the allograft, systemic concentration of FK506, anti-rejection activity, and side-effect of FK506 NPs were evaluated in a Brown Norway (BN)-to-Sprague Dawley (SD) epigastric VCA transplantation model.

Results

Compared with the nontreatment, PLGA control and FK506 groups, the median survival times (MST) of the FK506 NP groups were significantly prolonged. The FK506 NPs could maintain therapeutic drug concentration for 60 days. Moreover, cytokine concentrations, flow cytometry of regulatory T cells (Tregs) and histopathology of allografts revealed significantly prolonged immunosuppression by FK506 NPs. FK506 NPs also ameliorated FK506 nephrotoxicity.

Conclusions

FK506 NPs prolong the survival time of VCAs in a murine model with minimal nephrotoxicity, and provide a potential clinical strategy for ameliorating long-term side effects of immunosuppressive therapy.

Calcineurin Inhibition Causes α2δ-1-Mediated Tonic Activation of Synaptic NMDA Receptors and Pain Hypersensitivity

Calcineurin inhibitors, such as tacrolimus (FK506) and cyclosporine, are widely used as standard immunosuppressants in organ transplantation recipients. However, these drugs can cause severe pain in patients, commonly referred to as calcineurin inhibitor-induced pain syndrome (CIPS). Although calcineurin inhibition increases NMDAR activity in the spinal cord, the underlying mechanism remains enigmatic. Using an animal model of CIPS, we found that systemic administration of FK506 in male and female mice significantly increased the amount of α2δ-1-GluN1 complexes in the spinal cord and the level of α2δ-1-bound GluN1 proteins in spinal synaptosomes. Treatment with FK506 significantly increased the frequency of mEPSCs and the amplitudes of monosynaptic EPSCs evoked from the dorsal root and puff NMDAR currents in spinal dorsal horn neurons. Inhibiting α2δ-1 with gabapentin or disrupting the α2δ-1-NMDAR interaction with α2δ-1Tat peptide completely reversed the effects of FK506. In α2δ-1 gene KO mice, treatment with FK506 failed to increase the frequency of NMDAR-mediated mEPSCs and the amplitudes of evoked EPSCs and puff NMDAR currents in spinal dorsal horn neurons. Furthermore, systemic administration of gabapentin or intrathecal injection of α2δ-1Tat peptide reversed thermal and mechanical hypersensitivity in FK506-treated mice. In addition, genetically deleting GluN1 in dorsal root ganglion neurons or α2δ-1 genetic KO similarly attenuated FK506-induced thermal and mechanical hypersensitivity. Together, our findings indicate that α2δ-1-bound NMDARs mediate calcineurin inhibitor-induced tonic activation of presynaptic and postsynaptic NMDARs at the spinal cord level and that presynaptic NMDARs play a prominent role in the development of CIPS.SIGNIFICANCE STATEMENT Calcineurin inhibitors are immunosuppressants used to prevent rejection of transplanted organs and tissues. However, these drugs can cause severe, unexplained pain. We showed that calcineurin inhibition enhances physical interaction between α2δ-1 and NMDARs and their synaptic trafficking in the spinal cord. α2δ-1 is essential for calcineurin inhibitor-induced aberrant activation of presynaptic and postsynaptic NMDARs in the spinal cord. Furthermore, inhibiting α2δ-1 or disrupting α2δ-1-NMDAR interaction reduces calcineurin inhibitor-induced pain hypersensitivity. Eliminating NMDARs in primary sensory neurons or α2δ-1 KO also attenuates calcineurin inhibitor-induced pain hypersensitivity. This new information extends our mechanistic understanding of the role of endogenous calcineurin in regulating synaptic plasticity and nociceptive transmission and suggests new strategies for treating this painful condition.

ASP1126, a Novel Sphingosine-1-Phosphate-Selective Agonist With a Favorable Safety Profile, Prolongs Allograft Survival in Rats and Nonhuman Primates in Combination With Tacrolimus With a Broad Safety Margin for Bradycardia

Sphingosine-1-phosphate (S1P) is a biologically active sphingolipid that acts through the members of a family of 5 G protein-coupled receptors (S1P₁ to S1P₅). Among these, S1P₁ is a major regulator of lymphocyte trafficking. Fingolimod, whose active metabolite, fingolimod phosphate, acts as a nonselective S1P-receptor agonist, exerts its immunomodulatory effect, at least in part, by regulating lymphocyte trafficking via downregulation of S1P₁ expression on lymphocytes. Here, we describe the pharmacologic profile of a novel S1P₁ agonist, ASP1126. ASP1126 preferentially activated S1P₁ compared to S1P₃ in rat and human guanosine-5'-(γ-thio)-triphosphate (GTPγS) assays. Oral single administration of ASP1126 decreased the number of peripheral lymphocytes and repeated dosing showed a cumulative effect on lymphopenia in both rats and monkeys. ASP1126 prolonged allograft survival in a rat heterotopic heart transplantation model in combination with a subtherapeutic dose of tacrolimus that was independent of drug-drug interactions. In addition, in nonhuman primate (NHP) renal transplantation, pretreatment with ASP1126 reduced not only the number of naive T cells and central memory T cells but also effector memory T cells in the peripheral blood, all of which could contribute to acute graft rejection and prolonged allograft survival in combination with tacrolimus. Further, we confirmed that ASP1126 has a broad ranging safety margin with respect to its effect on lung weight in rats and bradycardia in NHPs, which were the adverse events found in clinical studies of fingolimod. ASP1126 with improved safety profile has the potential to be an adjunct therapy in combination with tacrolimus in clinical transplantation.

Neurological Complications After Renal Transplantation: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the prevalence of neurological complication after renal transplantation. The searches were conducted by two independent researchers in the international (PubMed, Web of Science, Scopus, and Google Scholar) and national databases (Magiran and SID) to find the relevant studies published in English and Persian languages since the creation of the databases until January 2019 (without time limitations). The keywords used in the search strategy were: neurologic complication, central nervous system, peripheral nervous system, tremor, CVA, encephalopathy, neurological complications, renal transplantation, renal failure, kidney transplantation, immunosuppression, neurotoxicity, opportunistic infections, CNS, cerebrovascular disease, chronic kidney disease, cognitive impairment, and end-stage renal disease, which were combined using the AND, OR, and NOT operators. Finally, a meta-analysis was conducted in STATA14 statistical software. Based on the random effect model, the total prevalence of neurologic complications in 4674 patients who had undergone the renal transplantation surgery was 7.9% (95% confidence interval [CI]:7.2%,8.7%, I² = 90.1%). The prevalence of infectious, non-infectious and treatment associated neurologic complications was 9.5% (95% CI -8.9, 10.2), 91.8% (95% CI -91.3, 92.4) and 97% (95% CI-95.7%,98.4%) of all neurologic complications in renal transplant patients, respectively. And according to the present subgroup analysis, peripheral neuropathy with a prevalence about 30% (29%) (95% CI -27.6%, 30.4%, I² = 99.4%) was the most common neurological disorder in renal transplant patients followed by tremor with a prevalence of 19.5% (CI -17.6%, 21.3%, I² = 97.1%), cerebrovascular events with a prevalence of 15.1% (95% CI -13.9%, 16.4%, I² = 96.5%), encephalopathy with the prevalence of 13% (95% CI -12%, 14%, I² = 99.3%), headache with a prevalence of 8.3% (95% CI -6.8%, 9.8%, I² = 97.3%) and seizure with a prevalence of 7.4% (CI - 6.5%, 8.3%, I² = 94.6%). The results of the present systematic review and meta-analysis, suggests that post-kidney transplantation neurological disorders, with a prevalence rate about 8%, are relatively common; most of them are caused by immunosuppressive drugs and can be treated by decreasing the dose or switching the immunosuppressive drugs. Neurological disorders are associated with increased mortality; thus, differential diagnosis should be conducted for each individual patient with neurological symptoms after transplantation. It is important for all health care providers to become familiar with the symptoms of neurological disorders that may occur after organ transplants. Recognizing and monitoring these symptoms can reduce the risk of death in kidney transplant recipients. Further research is needed to help the transplant community to identify these issues and problems better in order to achieve the ultimate goal of helping renal patients and sending them back into their normal lives.

Immunosuppressants in Organ Transplantation

The goal of immunosuppressive therapy post-transplantation in pediatric renal transplant recipients is to prevent acute and chronic rejection while minimizing drug side effects. Most therapies alter immune response mechanisms but are not immunologically specific, and a careful balance is required to find the dose that prevents rejection of the graft while minimizing the risks of overimmunosuppression leading to infection and cancer. While this chapter because of space constraints focuses on immunosuppressive therapy in pediatric renal transplant recipients, many aspects can be applied on pediatric recipients of other solid organ transplants such as the liver and heart. The major maintenance immunosuppressive agents currently used in various combination regimens are tacrolimus, cyclosporine, mycophenolate mofetil, azathioprine, everolimus, sirolimus, and glucocorticoids (steroids). Although data from adult renal transplantation trials are used to help guide management decisions in pediatric patients, immunosuppressive therapy in pediatric renal transplant recipients often must be modified because of the unique dosage requirements and clinical effects of these agents in children, including their impact on growth and development. The optimal immunosuppressive therapy post-transplant is not established. The goal remains to find the best combination of immunosuppressive agents that optimizes allograft survival by preventing acute rejection while limiting drug toxicities.

Increased Sensitivities of Peripheral Blood Mononuclear Cells to Immunosuppressive Drugs in Cirrhosis Patients Awaiting Liver Transplantation

Successful immunosuppressive therapy is critical for liver transplantation. However, a considerable number of patients show clinical resistance to the therapy and experience rejection episodes, or alternatively exhibits serious adverse effects of drugs. We examined the in vitro response of peripheral blood mononuclear cells (PBMCs) to immunosuppressive drugs in cirrhosis patients awaiting liver transplantation. We evaluated the suppressive efficacy of prednisolone, methylprednisolone, cyclosporine, and tacrolimus on the in vitro blastogenesis of PBMCs obtained from 22 cirrhosis patients and 31 healthy subjects. In vitro drug concentrations giving 50% inhibition of PBMC blastogenesis (IC50s) were calculated. Two out of these 22 patients received liver transplantation from living donors, and their clinical courses were surveyed until 5 weeks after operation. The median IC50 values for prednisolone, cyclosporine, and tacrolimus against blastogenesis of PBMCs from cirrhosis patients were significantly lower than those of PBMCs from healthy subjects (p < 0.01). However, large individual differences were observed in the IC50 values of the immunosuppressive drugs examined, especially in the cirrhosis patients. One recipient exhibiting high PBMC sensitivity to tacrolimus (IC50 = 0.001 ng/ml) showed good clinical course without rejection until 5 weeks after liver transplantation. The other recipient exhibiting relatively low PBMC sensitivity to taclolimus (IC50 = 0.30) showed allograft rejection at 1 week after operation. We concluded from these observations that PBMCs of cirrhosis patients are vulnerable to the immunosuppressive effects of prednisolone and calcineurin inhibitors. However, large individual variations in the IC50 values suggest that patients exhibiting relatively lower sensitivity to these drugs may have risks of rejection, whereas highly sensitive patients are possibly able to reduce the dose of immunosuppressive drugs to avoid serious drug-adverse effects, after liver transplantation.

Evaluation of Immunosuppressive Activity of Demethylzeylasteral in a Beagle Dog Kidney Transplantation Model

Several monomers isolated from Tripterygium wilfordii Hook f. (Celastraceae) have attracted worldwide interest. In this study, we established a simple and reliable kidney transplantation model in beagle dog to evaluate the immunosuppressive activity of demethylzeylasteral (T-96), an immunosuppressive monomer isolated from the root xylem of T. wilfordii. Recipient and donor male beagle dogs were obtained from two different breeders to ensure MHC mismatching. All dogs were randomly divided into six groups following kidney transplantation, and different doses of T-96 or cyclosporine A (CsA) were administered to each group during 14 days of observation. The results showed that T-96 alone at a dosage of 10 or 20 mg/kg/day prolonged graft survival up to 10.83 ± 1.47 or 11.17 ± 1.47 days. A combination of T-96 and CsA significantly prolonged the survival time to 13.33 ± 1.75 days. The results demonstrated that T-96 can inhibit acute rejection in kidney transplantation, and the inhibitory effect of T-96 was enhanced when combined with CsA, which suggests the possible use in organ transplantation to prevent immune rejection.

Effects of immunosuppressive drugs on oral mucosa in patients with Behçet's disease: cytomorphological and cytopathological assessment

BACKGROUND/AIM

The aim of this study was to investigate cytomorphological and cytopathological changes in oral exfoliated smears collected from immunosuppressed patients with Behçet's disease (BD) using stereological methods.

MATERIALS AND METHODS

For cytomorphometric analysis, mucosal cell smears were obtained from the buccal mucosa and the floor of the mouths of BD patients treated with immunosuppressive drugs and from healthy volunteers. All mucosal smears from the patients and the healthy volunteers were stained using the Papanicolaou method and examined cytopathologically under light microscopy and cytomorphologically via the stereological nucleator method.

RESULTS

The cytomorphological analysis revealed 3 types of mucosal cells, with numbers of particularly pink cells lower in the aphthous areas of the patients with BD compared to the healthy controls (P < 0.05). The nuclear volumes (NVs) and cytoplasmic volume (CVs) were significantly higher in the BD patients (P < 0.05), but the NV/CV ratio was higher only in the drug-use patient groups (P > 0.05). There was lower apoptotic activity in the nondrug-use patients with BD and in the immunosuppressive-taking BD patients.

CONCLUSION

The findings suggest that quantifiably morphological and morphometric changes in oral mucosa can be detected by stereological techniques. Changes in these parameters may indicate malignant transformation in the oral mucosa.

The metamorphosis of vascular stents: passive structures to smart devices

The role of nanotechnology enabled techniques in the evolution of vascular stents.

3D-Printed Drug/Cell Carrier Enabling Effective Release of Cyclosporin A for Xenogeneic Cell-Based Therapy

Systemic administration of the immunosuppressive drug cyclosporin A (CsA) is frequently associated with a number of side effects; therefore, sometimes it cannot be applied in sufficient dosage after allogeneic or xenogeneic cell transplantation. Local delivery is a possible solution to this problem. We used 3D printing to develop a CsA-loaded 3D drug carrier for the purpose of local and sustained delivery of CsA. The carrier is a hybrid of CsA-poly(lactic-co-glycolic acid) (PLGA) microsphere-loaded hydrogel and a polymeric framework so that external force can be endured under physiological conditions. The expression of cytokines, which are secreted by spleen cells activated by Con A, and which are related to immune rejection, was significantly decreased in vitro by the released CsA from the drug carrier. Drug carriers seeded with xenogeneic cells (human lung fibroblast) were subcutaneously implanted into the BALB/c mouse. As a result, T-cell-mediated rejection was also significantly suppressed for 4 weeks. These results show that the developed 3D drug carrier can be used as an effective xenogeneic cell delivery system with controllable immunosuppressive drugs for cell-based therapy.

Current and future treatments for Behçet's uveitis: road to remission

Behçet's disease (BD) is a multisystem inflammatory disorder of uncertain origin, although it remains defined within the spectrum of systemic immune-mediated vasculitic disorders and also represents a spectrum of putative autoimmune disease. Major symptoms include oral aphthous ulcers, genital ulcerations, skin lesions, and ocular lesions. Despite afflicting many systems, ocular complications of BD are some of the more devastating for the patient and their quality of life. Eye involvement, which affects 60-80 % of BD patients, is characterized in its more severe form by posterior or panuveitis including occlusive retinal vasculitis. While pathogenesis of BD remains complex, association with Class I MHC (HLA-B*51) predisposing to inflammation with engagement of the innate-immune system (neutrophils, NK cells), and perpetuated by the adaptive T cell responses against infectious- and/or auto-antigens. Despite the choice of conventional immunosuppressive therapies available, only recently with the advent of biologic therapy has visual prognosis and outcomes been substantially and favorably altered. For example, both interferon-α (IFN-α) and tumour necrosis factor (TNF)-α antagonists deliver promising results and for the first time improve prognosis. With IFN-α therapy, durable remissions of uveitis can be achieved and lead to drug-free remission. Similarly, anti-TNF therapy with infliximab is reported to be rapidly effective in inducing and maintaining remission. Most recently, rising evidence reports on the use of adalimumab, etanercept, and golimumab, while use of anti-interleukin (IL)-1 agents (anakinra, canakinumab, gevokizumab), IL-6 blockers (tocilizumab), and rituximab (depleting anti-CD20 antibody) is also increasing. The aim of this review is to provide evidence for the role of conventional therapies combined with evidence for advantages and disadvantages of biologic therapies in the treatment of ocular BD. Although randomized controlled trials remain sparse, evidence remains strong and enticing that biologic agents are invaluable for the treatment of sight-threatening Behçet's uveitis and makes it an exciting time for Behçet's specialists worldwide.

Protocol biopsies in pediatric renal transplant recipients on cyclosporine versus tacrolimus-based immunosuppression

BACKGROUND

Protocol biopsies can detect subclinical rejection and early signs of calcineurin inhibitor-induced nephrotoxicity.

METHODS

In a prospective study, protocol biopsies 3 and 12 months after transplant in transplanted children from two centers were studied. One center used cyclosporine (CsA)-based immunosuppression and the other center used tacrolimus. Patients were on CsA (n = 26, group 1) or on tacrolimus (n = 10, group 2). Patients received basiliximab induction, mycophenolate mofetil, and prednisone.

RESULTS

In patients on CsA, 26 kidney biopsies were performed during the 6 months after transplantation. Eighteen protocol biopsies were performed at 3 months post transplant; 13 were normal and five showed rejection (two borderline and three Banff II rejections). Eight biopsies were motivated by an increase of serum creatinine; four were normal and four revealed signs of acute rejection (two borderline and two Banff II). Twelve protocol biopsies were performed after 12 months; all were normal. For patients on tacrolimus (n = 10), ten protocol transplant biopsies were performed at 3 months post-transplant; none showed signs of rejection. No biopsy was performed for an increase of serum creatinine. There were no differences in patient age, number of human leukocyteantigen (HLA) incompatibilities, or other patient characteristics.

CONCLUSIONS

Patients on tacrolimus had less acute rejection episodes detected on protocol biopsies 3 months after transplant. Protocol biopsies seem to play an important role in the detection of subclinical rejection in patients on CsA.

Molecular Diagnostics of Calcineurin-Related Pathologies

BACKGROUND

The Ca2+-dependent protein phosphatase enzyme calcineurin (Cn) (protein phosphatase 3) is best known for its role as director of the adaptive immune response. One of its principal substrates is the nuclear factor of activated T cells (NFAT), which translocates to the nucleus after dephosphorylation to mediate gene transcription. Drugs targeting Cn (the Cn inhibitors tacrolimus and cyclosporin A) have revolutionized posttransplantation therapy in allograft recipients by considerably reducing rejection rates.

CONTENT

Owing primarily to intensive study of the side effects of the Cn inhibitors, the unique importance of Cn and Cn/NFAT signaling in the normal physiological processes of many other cell and tissue types is becoming more evident. During the last decade, it has become clear that an extensive and diverse array of clinical conditions can be traced back, at least in part, to a disturbed Cn-signaling axis. Hence, both diagnostics and therapeutic monitoring could benefit from a technique that conveniently reads out Cn/NFAT operative status.

SUMMARY

This review outlines the current knowledge on the pathologic conditions that have calcineurin as a common denominator and reports on the progress that has been made toward successfully applying Cn and Cn/NFAT activity markers in molecular diagnostics.

Fatores de risco cardiovascular em pacientes pediátricos após um ano de transplante renal

OBJETIVO: Identificar a frequência de diabetes mellitus e a presença de fatores de risco cardiovascular em pacientes pediátricos após um ano de transplante renal. MÉTODOS: Estudo retrospectivo, de cunho documental e exploratório, realizado de janeiro de 2000 a janeiro de 2006, abrangendo 111 prontuários de pacientes pediátricos (0 a 18 anos incompletos) submetidos a transplante renal no Hospital do Rim e Hipertensão e no Hospital São Paulo da Universidade Federal de São Paulo. RESULTADOS: Foram analisados 111 pacientes, 50,5% utilizavam anti-hipertensivos antes do transplante renal. Um ano após este número caiu para 28%. No pré-transplante 13,5% pacientes apresentaram sobrepeso e após um ano não houve alteração importante (12,6%). O número de pacientes obesos aumentou 50% após um ano de transplante renal. Aproximadamente 1% das crianças desenvolveram diabetes mellitus pós-tranplante renal. CONCLUSÃO: A presença de excesso de peso (sobrepeso e obesidade), hipertensão arterial e diabetes mellitus são freqüentes em pacientes pediátricos pós-tranplante renal.

Comparative study of the cellular pharmacodynamics of calcineurin inhibitors between patients with chronic renal failure awaiting renal transplantation and cirrhosis patients awaiting liver transplantation

The in vitro response of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of calcineurin inhibitors is known to correlate with the clinical efficacy of drugs used in renal transplantations. The present study was conducted to examine the differences of PBMC responses to calcineurin inhibitors between chronic renal failure (CRF) patients awaiting renal transplantation and cirrhosis patients awaiting liver transplantation. The study included 99 CRF patients awaiting renal transplantation and 27 cirrhosis patients awaiting liver transplantation. Twenty milliliters of venous blood was taken 1-7 days before transplantation. The in vitro drug concentrations giving 50% inhibition of PBMC blastogenesis stimulated with concanavalin A (IC(50)s) were calculated. The suppressive effects of tacrolimus against PBMC blastogenesis were more than 10-100 times stronger than those of cyclosporine. The median IC(50) value for cyclosporine against the CRF PBMCs was not significantly different from the median IC(50) value against the cirrhosis PBMCs. In contrast, tacrolimus sensitivity in cirrhosis PBMCs is approximately seven times higher than that in CRF PBMCs. The median IC(50) value for tacrolimus against cirrhosis PBMCs was significantly lower and therefore the effect was stronger in comparison to the CRF PBMCs (p < 0.001). These data suggest that the PBMCs of cirrhosis patients, in comparison to those of CRF patients, are highly sensitive to the suppressive effect of tacrolimus. However, PBMC sensitivity to cyclosporine was not significantly different between the CRF and cirrhosis patients. These observations raise the possibility that treatment with tacrolimus, rather than cyclosporine, may therefore be a better choice to reduce the risks of allograft rejection in liver transplantation.

PSYCHOSOCIAL FACTORS IN PATIENTS WITH CHRONIC KIDNEY DISEASE: Life After Transplantation: New Transitions in Quality of Life and Psychological Distress

Individuals with kidney failure often elect to undergo kidney transplantation because they believe that they will be more active and return a sense of normality to their lives with a functioning transplant. Therefore it is important to assess whether these objectives are being met. To do so, we can examine health-related quality of life (HRQOL) in transplant recipients. A number of tools have been used for this purpose, including general HRQOL instruments such as the 36-item short-form health survey (SF-36) and transplant-specific surveys such as the Kidney Transplant Questionnaire. In general, HRQOL assessments improve with transplantation in functional and physical domains. However, many factors actually influence HRQOL in a negative way, including comorbid conditions, kidney function per se, rejection episodes and hospitalizations, employment status, and adverse effects of medications. Perceived physical appearance, issues related to sexuality, stress, anxiety, and even guilt complicate the emotional and psychological landscape after transplantation. This constellation of factors may be predictive of posttransplant life events, such as resumption of employment. Posttransplant HRQOL may be exceedingly important in understanding the issues related to adherence with treatment regimens, especially in the pediatric and adolescent transplant populations. HRQOL is now established as an important issue after transplantation. Nonetheless, shortcomings still exist in our ability to address HRQOL after transplantation. In particular, more study of patient-centered interventions is needed. The use of standardized methodologies for patient assessment could improve our ability to identify if such patient-centered interventions actually succeed across populations, and help us further address the panoply of factors encompassed within posttransplant HRQOL.

Colutellin A, an immunosuppressive peptide from Colletotrichum dematium

Colletotrichum dematium is an endophytic fungus recovered from a Pteromischum sp. growing in a tropical forest in Costa Rica. This fungus makes a novel peptide antimycotic, colutellin A, with a MIC of 3.6 microg ml(-1) (48 h) against Botrytis cinerea and Sclerotinia sclerotiorum. Collutellin A has a mass of 1127.7 Da and contains residues of Ile, Val, Ser, N-methyl-Val and beta-aminoisobutryic acid in nominal molar ratios of 3 : 2 : 1 : 1 : 1, respectively. Independent lines of evidence suggest that the peptide is cyclic and sequences of Val-Ile-Ser-Ile and Ile-Pro-Val have been deduced by MS/MS as well as Edman degradation methods. Colutellin A inhibited CD4(+) T-cell activation of interleukin 2 (IL-2) production with an IC(50) of 167.3+/-0.38 nM, whereas cyclosporin A in the same test yielded a value of 61.8 nM. Inhibition of IL-2 production by collutellin A at such a low concentration indicates the potential immunosuppressive activity of this compound. In repeated experiments, cyclosporin A at or above 8 microg ml(-1) exhibited high levels of cytotoxicity on human peripheral blood mononuclear cells, whereas collutellin A or DMSO (carrier) alone, after 24 and 48 h of culture, exhibited no toxicity. Because of these properties collutellin A has potential as a novel immunosuppressive drug.

Immunosuppressive therapy and malignancy in organ transplant recipients: a systematic review

Post-transplant malignancy is recognised as being a major limitation to the success of solid organ transplantation and it is currently considered one of the unavoidable costs of long-term immunosuppressive therapy. However, the continual introduction of new immunosuppressive drugs and the growing knowledge about their different oncogenic profiles, requires a continuous evaluation of the available evidence on this topic. The incidence and risk of malignancy is elevated in solid organ transplant recipients compared with the general population. As proof of the relationship between immunosuppressive therapy and post-transplant malignancy, epidemiological data reveal that the length of exposure to immunosuppressive therapy and the intensity of therapy are clearly related to the post-transplant risk of malignancy, and that once cancer has developed, more intense immunosuppression can translate into more aggressive tumour progression in terms of accelerated growth and metastasis and lower patient survival. The association between malignancy and immunosuppressive therapy is mediated through several pathogenic factors. Indirectly, immunosuppressive drugs greatly increase the post-transplant risk of malignancy by impairing cancer surveillance and facilitating the action of oncogenic viruses. However, the direct pro- and anti-oncogenic actions of immunosuppressants also play an important role. The cancer-promoting effect of calcineurin inhibitors, independently of depressed immunosurveillance, has been demonstrated in recent years, and currently only mammalian target of rapamycin (mTOR) inhibitors have shown simultaneous immunosuppressive and antitumour properties. Reports of the initial results of the reduced incidence of cancer in organ transplant recipients receiving mTOR inhibitor therapy strongly indicate separate pathways for pharmacological immunosuppression and oncogenesis. The role of mTOR inhibitors has been firmly established for the treatment of post-transplant Kaposi's sarcoma and its role in the management of patients with other post-transplant malignancies should be clarified as soon as possible. Prevention of morbidity and mortality resulting from post-transplant malignancy should become a main endpoint in solid organ transplant programmes, and the choice and management of immunosuppressive therapy in each phase of transplantation plays a central role in this objective. Although comprehensive and rigorous information about the management of immunosuppressive therapy in transplant recipients at risk of or affected by cancer is still lacking, new experimental and clinical data about mTOR inhibitors offers novel approaches to this problem.

Calcineurin inhibitors in pediatric renal transplant recipients

The calcineurin inhibitors, cyclosporine (ciclosporin) [microemulsion] and tacrolimus, are the principal immunosuppressants prescribed for adult and pediatric renal transplantation. For pediatric patients, both drugs should be dosed per body surface area, and pharmacokinetic monitoring is mandatory. While monitoring of the trough levels may suffice for tacrolimus, cyclosporine therapy that utilizes the microemulsion formulation requires additional monitoring (e.g. determination of 2-hour post-dose levels). In a well designed randomized study in children, as in studies in adults, there was no difference in short-term patient and graft survival with cyclosporine microemulsion and tacrolimus. However, tacrolimus was significantly more effective than cyclosporine microemulsion in preventing acute rejection after renal transplantation when used in conjunction with azathioprine and corticosteroids. With regard to long-term outcome, the difference in acute rejection episodes resulted in a better glomerular filtration rate at 1 year after transplantation and eventually in better graft survival 4 years after renal transplantation. Whether this difference persists when calcineurin inhibitors are used in combination with mycophenolate mofetil has not been determined. The prevalence of hypomagnesemia was higher in the tacrolimus group whereas hypertrichosis and gingival hyperplasia occurred more frequently in the cyclosporine group. In contrast with adults, the incidence of post-transplantation diabetes mellitus was not significantly different between tacrolimus- and cyclosporine-treated patients. There was also no difference with regard to post-transplantation lymphoproliferative disorder. Medication costs were similar, but in view of the lower rejection episodes and better long-term graft survival as well as the more favorable cosmetic side effect profile, tacrolimus may be preferable. The recommendation drawn from the available data is that both cyclosporine and tacrolimus can be used safely and effectively in children. We recommend that cyclosporine should be chosen when patients experience tacrolimus-related adverse events.

Current and evolving immunosuppressive regimens in kidney transplantation

The advent of novel immunosuppressive agents with increased potency now offers multiple treatment options for transplant physicians. However, variable efficacy, drug-drug interactions, and adverse effects associated with long-term immunosuppression continue to complicate the clinical management of kidney transplant recipients. Currently, investigators are challenged to develop regimens that take into account not only efficacy, but also dosing, monitoring, safety, and patient quality of life. Recent research has focused on evaluating new combinations of approved agents that seek to improve outcomes by improving control of immunologic events with fewer complications. This article reviews current practice and recent studies to give all health care providers who manage kidney transplant recipients a better understanding of current regimens and general trends in immunosuppressive therapy.

Renal graft survival and calcineurin inhibitor

BACKGROUND

Tacrolimus is associated with fewer acute rejections than cyclosporine, but a greater risk of new onset diabetes mellitus. When compared to no tacrolimus among nondiabetics in a large patient registry, it is associated with improved graft survival. The current study used the same patient registry to compare more correctly graft survival between nondiabetic renal transplant recipients initially immunosuppressed with either of the two most frequently used calcineurin inhibitors, tacrolimus or modified cyclosporine (CsA).

METHODS

We examined data provided by the United States Renal Data System (USRDS) on all first, single-organ, renal transplants to nondiabetic recipients that occurred during the years 1996 to 2000. Importantly, we then limited the study to patients on CsA (n = 7,867) or tacrolimus (n = 3,082) as the initial agent. Patients with both or neither were excluded. We used Cox proportional hazards regressions to estimate the tacrolimus-related relative risk of graft failure, controlling for other significant donor, recipient, and transplant characteristics

RESULTS

We found that tacrolimus patients had graft failure rates equivalent to those of CsA patients (hazard ratio= 1.031, P = 0.631)

CONCLUSIONS

Although tacrolimus is being used with increasing frequency, analyses of the USRDS data show no net advantage in the ultimate transplantation outcome, graft survival. Given the higher acquisition price of tacrolimus compared to CsA and the similar risk of graft failure, further studies should be conducted to define those patient groups for which tacrolimus might be cost-effective.

What we CAN do about chronic allograft nephropathy: Role of immunosuppressive modulations

Given the potency of modern immunosuppressive agents, kidney transplantation across alloantingen barriers is a routine phenomenon with excellent 1-year graft survival in most centers. However, the improvement in 1-year graft survival has not been matched by improvements in long-term graft function and chronic allograft nephropathy (CAN) remains the second commonest cause of graft attrition over time. Calcineurin inhibitors, namely cyclosporine A (CyA) and tacrolimus, have been implicated as causal agents in the development of the fibrotic processes that are the hallmarks of CAN. Many studies have, therefore, concentrated on the improvement of long term graft function through the modulation of immunosuppressive therapy. It is the purpose of this review to describe and appraise the available evidence for the prevention and management of CAN through modulation of immunosuppressive agents.

Outcome of renal transplants from pediatric donors <5 yr of age

AIM

Outcomes of single renal transplants from donors <5 yr old have traditionally been inferior to those from older donors. We retrospectively studied our experience with patients who received renal transplants, either individually or en bloc, from young donors (<5 yr of age) to determine the utility of these organs. We also compared the outcomes of these transplant patients maintained on either cyclosporine- (CyA) or tacrolimus-based (TRL) immunosuppression regimens.

PATIENTS

Ninety-eight patients received transplants at our center from donors <5 yr of age between August 1993 and August 2003. They were followed-up from 12 months to 11 yr. Patients were divided into four groups based on whether they received single or en bloc transplants, and whether CyA or TRL was the base immunosuppressive agent. Patients in group I (n = 13) received single pediatric kidneys and were treated with CyA regimens; group II patients (n = 26) also received single pediatric kidneys, but were treated with TRL regimens; group III patients (n = 31) were transplanted en bloc and were treated with CyA; and group IV patients (n = 28) received en bloc transplants and were treated with TRL.

RESULTS

One-year patient and death-censored graft survival was not significantly different between recipients of en bloc vs. single grafts (i.e. 88 and 85% vs. 90 and 87%, respectively), or between the four treatment groups (group I: 85 and 85%, group II: 92 and 88%, group III: 87 and 84%, and group IV: 89 and 86%, respectively). The overall 1-yr rejection rate was 30% (29 of 98), which was significantly higher in the CyA-treated patients 19 of 44; i.e. 43%, than in TRL-treated patients 10 of 54, i.e. 19%, p = 0.03). In the en bloc recipients, seven grafts (12%) were lost as a result of vascular thrombosis. Notably, none of the single kidneys were lost because of vascular thrombosis. At the end of follow-up the creatinine levels of both groups were comparable.

CONCLUSIONS

Pediatric donor kidneys transplanted individually provide for equal patient and graft survival when compared with en bloc transplants. TRL can be used reduce the detrimental effect of acute rejection on graft growth and function when compared with CyA. Single use of such kidneys can safely and efficaciously be transplanted into adult recipients, greatly expanding the donor pool.

Dexamethasone Induces IL-10-Producing Monocyte-Derived Dendritic Cells with Durable Immaturity

It is highly desirable that immature dendritic cells (DC) used for tolerance induction maintain steady immature state with predominant interleukin (IL)-10 production. In this study, we attempted to develop DC with durable immaturity and other tolerogenic features by using dexamethasone (Dex). We found DC derived from human monocytes in the presence of 10(-7) m Dex were negative for CD1a. Compared with control transduced DC (Ctrl-DC), Dex-DC expressed lower CD40, CD80 and CD86 but equivalent human leucocyte antigen-DR. Both immature Dex- and Ctrl-DC did not express CD83. Nevertheless, upon stimulation of lipopolysaccharide (LPS) or CD40 ligand, the expression of CD40, CD80, CD83 and CD86 was upregulated on Ctrl-DC but not on Dex-DC. The immaturity of Dex-DC was durable following Dex removal. Interestingly, Dex-DC maintained production of large amount of IL-10 and little IL-12 five days after Dex removed. Further study indicated that high-level IL-10 production by Dex-DC was associated with high-level phosphorylation of extracellular signal-regulated kinase (ERK) as blockade of this enzyme markedly attenuated IL-10 production. Furthermore, Dex-DC sustained the capability of high phosphorylation of ERK and IL-10 production 5 days after Dex removal. In addition, Dex-DC had significantly lower activity in stimulating T-cell proliferation. Neutralization of IL-10, to some extent, promoted DC maturation activated by LPS, as well as T-cell stimulatory activity of Dex-DC. The above findings suggest that IL-10-producing Dex-DC with durable immaturity are potentially useful for induction of immune tolerance.

Rheological Properties of Red Blood Cells in Kidney Transplant Recipients: The Role of Lipid Profile and Type of Immunosuppresion

INTRODUCTION

The main rheological properties of red blood cells (RBC) are deformability and aggregability. Deformability is one of the most important factors of RBC flow in high-shear rate areas, especially in the microcirculation. Aggregability of erythrocytes can impair circulation in low-shear rate areas. Both deformability and aggregability of RBC are abnormal in patients with renal insufficiency and after kidney transplantation. Cyclosporine (CsA) and less frequently tacrolimus (Tc) may cause hyperlipidemia and hypertension. Dobiasova et al proposed the term Atherogenic Index of Plasma (AIP), defined as a log (TG/HDL-C). Subjects with high AIP have and higher risk of cardiovascular complications due to atherosclerosis. Hence the aim of this study was to compare aggregability and deformability of RBC from kidney transplant recipients on CsA or Tc-based immunosuppression with healthy volunteers and subjects with dyslipidemia (control groups). Both control and transplant recipient groups were arbitrarily divided by value of AIP as < or = 0 (AIP-) or >0 (AIP+). Deformability and aggregability of erythrocytes were measured using Rheodyn SSD and Myrenne Aggregometer, respectively.

RESULTS

We observed a significant increase in aggregation index at stasis in CsA-treated patients and an increased deformability in Tc-treated patients with negative AIP. Deterioration of hemorheological properties of RBC in kidney transplant recipients was confined to an increased aggregability in CsA-treated patients regardless of AIP value. An increased deformability of RBC in Tc-treated patients with normal lipid profiles may suggest a positive effect of Tc on mechanical properties of RBC.

Maintenance immunosuppression use and the associated risk of avascular necrosis after kidney transplantation in the United States

BACKGROUND

Avascular necrosis (AVN) after renal transplantation has been largely attributed to the use of corticosteroids. However, other risk factors such as microvascular thrombosis and hyperlipidemia have been well described and may be of increased importance in the era of early steroid cessation and avoidance. We hypothesized that maintenance immunosuppressive medications known to be associated with these risk factors for AVN would also be associated with a higher risk of AVN.

METHODS

By using the U.S. Renal Data System database, we studied 27,772 primary patients on Medicare who received a solitary kidney transplant between January 1, 1996, and July 31, 2000. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (AHRs) for patient- and transplant-related factors (including allograft rejection) with Medicare claims for AVN. The intensity and duration of corticosteroid use could not be assessed.

RESULTS

Among patients who were prescribed sirolimus at discharge, 3.5% of patients who received the combination of sirolimus-cyclosporine A (CsA) demonstrated AVN, compared with 1.4% of patients who received the combination of sirolimus-tacrolimus (P=0.06 by chi). In Cox regression, CsA use (vs. tacrolimus) (AHR 1.36, 95% confidence interval, 1.09-1.71) was independently associated with an increased risk of AVN. Sirolimus use showed a trend toward significance (AHR 1.59, 95% confidence interval, 0.99-2.56), with no significant interaction with CsA.

CONCLUSIONS

Compared with other maintenance immunosuppression, AVN was significantly more common after use of CsA prescribed at the time of discharge for renal transplantation. Whether this increased risk of AVN was directly attributable to hyperlipidemia, microvascular thrombosis, or differences in corticosteroid dosing could not be determined.

What is the calcineurin inhibitor of choice for pediatric renal transplantation?

Cyclosporine microemulsion (CyA) and tacrolimus (Tac) are the principal immunosuppressants prescribed for adult and pediatric renal transplantation. In the majority of patients, these calcineurin inhibitors have been used in combination with other immunosuppressive drugs, such as azathioprine or mycophenolate mofetil (MMF). In this review we will address the question of what calcineurin inhibitor we should use in an individual pediatric renal transplant patient. Well-designed randomized studies in children showed no difference in short-term patient and graft survival with cyclosporine microemulsion and tacrolimus. However Tac is significantly more effective than CyA microemulsion in preventing acute rejection after renal transplantation in a pediatric population when used in conjunction with azathioprine and corticosteroids. This difference disappears when calcineurin inhibitors are used in combination with MMF as both Tac and CyA produce similar rejection rates and graft survival. However, Tac is associated with improved graft function at 1 and 2 yr post-transplant. Adverse events of hypomagnesaemia and diarrhea seem to be higher in Tac group whereas hypertrichosis, flu syndrome and gum hyperplasia occurs more frequently in the CyA group. The incidence of post-transplant diabetes mellitus was almost identical between Tac and CyA treated patients. The recommendation drawn from the available data is that both CyA and Tac can be used safely and effectively in children. However Tac may be preferable to CyA because of steroid sparing effect and less hirsutism. We recommend that cyclosporine should be chosen when patients experience Tac-related adverse events. Nevertheless, the best calcineurin inhibitor should be decided on individual patients according to variable risk factors, such as risk of rejection in sensitized patient or delayed graft function. The possibility of adverse events should also be considered.

Impact of kidney transplantation on the progression of cardiovascular disease

Kidney transplantation, of all the treatment modalities for end-stage renal disease, affords the greatest potential for prolonged survival and improved quality of life. Great strides in immunosuppressant therapy have improved graft survival and forced clinicians to consider other health-care needs of kidney transplant recipients. Chief among these needs is the prevention and treatment of cardiovascular disease. Cardiovascular disease is the most common cause of death among patients with a working renal allograft. Because therapies for primary and secondary prevention are successful in the general population, transplant clinicians are increasingly focused on preventing or limiting the progression of cardiovascular disease. Initiation of aggressive management of conventional atherosclerotic risk factors and uremia-related risk factors, ideally during the early stages of chronic kidney disease (CKD) or after kidney transplantation, and efforts to delay the progression of kidney disease will hopefully reduce the cardiovascular burden in transplant recipients.

Cyclosporine: advantages versus disadvantages vis-à-vis tacrolimus

Despite a different molecular structure and biochemical properties, cyclosporine and tacrolimus--by inhibiting calcineurin activity--have been shown in the previous two decades of solid organ transplantation to be well tolerated and effective immunosuppressants. Initial randomized clinical trials showed a lower incidence of acute rejection in tacrolimus than in cyclosporine-treated patients, in combination with steroids and azathioprine. But in conjunction with mycophenolate mofetil, the difference in the incidence of acute rejection episodes is less clear. In general, short- and medium-term outcome variables (1-year serum creatinine, graft and patient survival) with cyclosporine and tacrolimus are excellent, and (almost) identical, with both substances having the same intrinsic nephrotoxic potential. On the other hand, cyclosporine and tacrolimus have a different impact on cardiovascular risk factors with tacrolimus having a better profile on arterial tension and lipid metabolism and cyclosporine on glucose metabolism. However, at present no data are available to discern that these differences in risk profile alter patient or graft survival or long-term cardiovascular morbidity/mortality. Therefore, prospective long-term trials are needed to study the quantitative impact of different immunosuppressive agents and concomitant cardiovascular risk factors on long-term patient and graft survival, before evidence-based (patient, graft, or cardiovascular) risk reduction can be firmly claimed by tailoring calcineurin inhibitors.