Integration of Islet/Beta-Cell Transplants with Host Tissue Using Biomaterial Platforms.

Cell-based therapies are emerging for type I diabetes mellitus (T1D), an autoimmune disease characterized by the destruction of insulin-producing pancreatic ß-cells, as a means to provide long-term restoration of glycemic control. Biomaterial scaffolds provide an opportunity to enhance the manufacturing and transplantation of islets or stem cell-derived ß-cells. In contrast to encapsulation strategies that prevent host contact with the graft, recent approaches aim to integrate the transplant with the host to facilitate glucose sensing and insulin distribution, while also needing to modulate the immune response. Scaffolds can provide a supportive niche for cells either during the manufacturing process or following transplantation at extrahepatic sites. Scaffolds are being functionalized to deliver oxygen, angiogenic, anti-inflammatory, or trophic factors, and may facilitate cotransplantation of cells that can enhance engraftment or modulate immune responses. This local engineering of the transplant environment can complement systemic approaches for maximizing ß-cell function or modulating immune responses leading to rejection. This review discusses the various scaffold platforms and design parameters that have been identified for the manufacture of human pluripotent stem cell-derived ß-cells, and the transplantation of islets/ß-cells to maintain normal blood glucose levels.

JAK3 inhibitor-based immunosuppression in allogeneic islet transplantation in cynomolgus monkeys.

Islet transplantation is efficacious to prevent severe hypoglycemia and glycemic liability of selected patients of type 1 diabetes. However, since calcineurin inhibitor (CNI) causes ß-cell and nephrotoxicity, alternative drug(s) with similar potency and safety profile to CNI will be highly desirable. Here we tested whether JAK3 inhibitor, tofacitinib could be used instead of tacrolimus in CIT07 immunosuppression regimen in cynomolgus nonhuman primate (NHP) model. Five independent streptozotocin (STZ)-induced diabetic monkeys were transplanted with MHC-mismatched allogeneic islets and three animals were further re-transplanted upon insufficient glycemic control or early islet graft rejection. After islet transplantation, blood glucose levels were quickly stabilized and maximal islet graft survival as measured by serum C-peptide concentration was >330, 98, >134, 31, or 22 days, respectively, after transplantation (median survival day; 98 days). Cellular and humoral immune responses were efficiently suppressed by JAK3 inhibitor-based immunosuppression during the follow-up periods. Although intermittent increases of the genome copy number of cynomolgus cytomegalovirus (CMV) were detected by quantitative real-time PCR analyses, serious infections or posttransplant lymphoproliferative disease (PTLD) was not found in all animals. Taken together, we have shown that JAK3 inhibitor could be used in replacement of tacrolimus in a highly translatable NHP islet transplantation model and these results suggest that JAK3 inhibitor will be potentially incorporated in human allogeneic islet transplantation.

Cyclophosphamide-Induced Tolerance in Allogeneic Transplantation: From Basic Studies to Clinical Application.

Immune tolerance against alloantigens plays an important role in the success of clinical organ and allogeneic hematopoietic stem cell transplantation. The mechanisms of immune tolerance to alloantigens have gradually been elucidated over time. Although there have been numerous reports to date on the induction of tolerance to alloantigens, the establishment of mixed chimerism is well-known to be crucial in the induction and maintenance of immune tolerance for either of the methods. Since the early 1980s, the murine system of cyclophosphamide (Cy)-induced tolerance has also been examined extensively. The present review focuses on studies conducted on Cy-induced immune tolerance. Clinical data of patients with allogeneic transplantation suggest that the posttransplant Cy method to induce immune tolerance has been successfully translated from basic studies into clinical practice.

The Effects of Anti-LAP Monoclonal Antibody Down-regulation of CD4+LAP+ T Cells on Allogeneic Corneal Transplantation in Mice.

CD4+latency-associated peptide (LAP)+ T cells are a newly discovered T cell subset with suppressive function on immune responses. In this study, we investigate the role of CD4+LAP+ T cells on mice corneal allograft survival by down-regulating their expression using anti-LAP mAb. We show that a blockage of LAP leads to a decrease in the percentage of T cells expressing CD4+Foxp3+, CD4+GARP+, CD4+LAP+ and CD4+IL-10+ in the lymph nodes and spleens of mice undergoing orthotopic penetrating transplantation of corneal allograft, without affecting corneal graft survival. In addition, higher percentages of CD4+IFN-γ+ and CD4+IL-17A+ T cells in the lymph nodes and spleens, as well as TNF, IFN-γ, IL-17A and IL-6 levels in the aqueous humor, significantly increase in mice with rejected corneal grafts. The expression of TGF-ß1 decreases in corneal grafts during corneal rejection period. It is therefore possible that anti-LAP mAb can down-regulate the regulatory T cell subsets with its immunosuppressive effects. The rejection of corneal grafts seems to mainly be associated with the up-regulation of Th1 and Th17 cell subsets in peripheral lymph nodes.

Serial Monitoring of Immune Markers Being Represented Regulatory T Cell/T Helper 17 Cell Ratio: Indicating Tolerance for Tapering Immunosuppression after Liver Transplantation.

Recipients of liver transplantation (LT) require long-term immunosuppressive drug treatment, but lifelong immunosuppressive treatment has severe side effects. It is known that some LT recipients develop immune tolerance, and although the development of such operational tolerance should allow a decrease in the burden of immunosuppressive drug treatment, the factors that indicate operational tolerance are not clear. This study aimed to monitor immunological markers over time in LT recipients to identify those markers indicating the development of operational tolerance. We performed a prospective pilot study measuring immune markers, including the ratio of regulatory T (Treg) and T helper (Th) 17 cells in peripheral blood in the 14 most immunologically stable patients among 70 clinically stable LT recipients. The doses of immunosuppressive drugs given to these 14 LT recipients were tapered over time and they were monitored for immunological markers related to the development of immune tolerance. As the doses of immunosuppressive drugs were reduced, the Treg/Th17, Th1/Th17, and CD8/Th17 ratio in tolerant recipients was significantly increased compared with that of nontolerant recipients. These results suggest that monitoring of changes in the immune makers, including Treg/Th17 ratio during tapering of immunosuppression may allow prediction of the development of tolerance.

Osteoporosis following heart transplantation and immunosuppressive therapy.

Heart transplantation (HT) remains the ultimate final therapy for patients with end-stage heart failure, who despite optimal medical and surgical treatments exhibit severe symptoms. To prevent rejection of the transplanted organ, HT patients require life-long immunosuppressive therapy. The goal of the immunosuppression is to minimise the risk of immune-mediated graft rejection, while avoiding clinical side-effects. Current immunosuppressive agents have yielded good survival outcome, however, complications of the immunosuppressive therapy, such as impaired bone strength and increased fracture risk, are common among HT patients rendering increased morbidity and mortality rates. The main aim of the present review was to summarise current knowledge on bone strength impairment after HT and concomitant immunosuppressive therapy.

Immunosuppression for kidney transplantation: Where are we now and where are we going?

Advances in immunosuppression have propelled kidney transplantation from a scientific curiosity to the optimal treatment for patients with end stage kidney disease. Declining rates of acute rejection have led to improvements in short term kidney transplant survival, culminating in incrementally better long term patient and allograft outcomes. Contextualized around established immune-suppressing drug targets, this review summarizes the history of the clinical science and highlights the pivotal trials that have led to present-day treatment standards at the level of both individual agents and multidrug regimens for kidney recipients. Finally, recently approved and emerging therapies are discussed, with an emphasis on challenges faced by clinicians managing this increasingly complex patient population.

Efficacy of a medication adherence enhancing intervention in transplantation: The MAESTRO-Tx trial.

BACKGROUND: Well-designed randomized controlled trials (RCTs) testing efficacy of post-transplant medication adherence enhancing interventions and clinical outcomes are scarce. METHODS: This randomized controlled trial enrolled adult heart, liver, and lung transplant recipients who were >1 year post-transplant and on tacrolimus twice daily (convenience sample) (visit 1). After a 3-month run-in period, patients were randomly assigned 1:1 to intervention group (IG) or control group (CG) (visit 2), followed by a 6-month intervention (visits 2-4) and a 6-month adherence follow-up period (visit 5). All patients used electronic monitoring for 15 months for adherence measurement, generating a daily binary adherence score per patient. Post-intervention 5-year clinical event-free survival (mortality or retransplantation) was evaluated. The IG received staged multicomponent tailored behavioral interventions (visits 2-4) building on social cognitive theory and trans-theoretical model (e.g., electronic monitoring feedback, motivational interviewing). The CG received usual care and attended visits 1-5 only. Intention-to-treat analysis used generalized estimating equation modeling and Kaplan-Meier survival analysis. RESULTS: Of 247 patients, 205 were randomly assigned (103 IG, 102 CG). At baseline, average daily proportions of patients with correct dosing (82.6% IG, 78.4% CG) and timing adherence (75.8% IG, 72.2% CG) were comparable. The IG had a 16% higher dosing adherence post-intervention (95.1% IG, 79.1% CG; p < 0.001), resulting in odds of adherence being 5 times higher in the IG than in the CG (odds ratio 5.17, 95% confidence interval 2.86-9.38). This effect was sustained at end of follow-up (similar results for timing adherence). In the IG, 5-year clinical event-free survival was 82.5% vs 72.5% in the CG (p = 0.18). CONCLUSION: Our intervention was efficacious in improving adherence and sustainable. Further research should investigate clinical impact, cost-effectiveness, and scalability.

Humoral Compensation after Bortezomib Treatment of Allosensitized Recipients.

The efficacy of bortezomib monotherapy in desensitizing kidney transplant candidates with preformed donor-specific antibodies remains unclear. We evaluated the effect of bortezomib on preformed antibodies and upstream components of the B cell response in a primate model sensitized by fully mismatched allogeneic skin transplants to provide mechanistic insights regarding the use of bortezomib as a means of desensitization. Bortezomib treatment given intravenously twice weekly for 1 month (1.3 mg/m2 per dose) clearly reduced the numbers of antibody-producing cells and CD38+CD19+CD20- plasma cells in the bone marrow (P<0.05), but donor-specific alloantibody levels did not decrease. We observed a rapid but transient induction of circulating IgG+ B cells and an increased number of proliferating B cells in the lymph nodes after 1 month of treatment. Notably, bortezomib treatment induced germinal center B cell and follicular helper T cell expansion in the lymph nodes. These data suggest that bortezomib-induced plasma cell depletion triggers humoral compensation.

Chronic allograft injury: Mechanisms and potential treatment targets.

Improving long-term graft survival remains one of the critical challenges facing kidney transplantation since a great portion of kidney grafts are lost by 10years after transplantation. Understanding the causes of chronic allograft injury and providing timely therapeutic interventions are essential for improving these outcomes. In this review, we will discuss the recent data that emerged turning down calcineurin inhibitors as the primary cause of long-term graft injury and highlighting the increased importance of non-compliance, antibody-mediated injury, disease recurrence, and BK nephropathy as culprits. We suggest a number of different strategies to better manage kidney transplant recipients that, ultimately, may improve long-term graft survival.

Análisis de costo efectivi dad de everolimus más tacrolimus y prednisolona comparado con tacrolimus más prednisolona para la inmunosupresión de mantenimiento en el trasplante hepático en Colombia / Cost-effectiveness analysis of everolimus plus tacrolimus and prednisolone compared to tacrolimus plus prednisolone for maintenance immunosuppression in liver transplantation in Colombia

Problema de investigación: Calcular los costos y la efectividad esperados del Everolimus más Tacrolimus (dosis reducida) y Corticosteroide (ETC) comparado con Tacrolimus (dosis estándar) más Corticoesteroide (TC) para el tratamiento de pacientes colombianos, adultos, receptores de trasplante de hígado por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Tipo de evaluación económica: Análisis de costo-efectividad. Población objetivo: Análisis de costo-efectividad. Población objetivo: Pacient es colombianos, adultos, receptores de trasplante de hígado por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Intervención y comparadores: I: Everolimus más Tacrolimus (dosis reducida) y Corticosteroide (ETC). C: Tacrolimus (dosis estándar) más Corticoesteroides (TC). Horizonte temporal: Vital. Perspectiva: Sistema General de Seguridad Social en Salud (SGSSS). Tasa de descuento: Se emplea una tasa de descuento común tanto a los costos como a los desenlaces en salud, equivalente al 5 % anual. Adicionalmente, se realizan análisis de sensibilidad de 0 %, 3,5 %, 7 % y 12 %. Estructura del modelo: Modelo de Markov anidado en un árbol de decisiones. Fuentes de datos de efectividad y seguridad: Fueron usados los recursos siguientes: el Reporte de efectividad y seguridad de las alternativas a evaluar previamente publicado por el IETS, los resultados de una búsqueda de literatura económica en las base de datos del CRD, de una búsqueda manual de literatura económica y clínica, y la información obtenida producto de la consulta a expertos clínicos. Desenlaces y valoración: Años de vida ganados. Costos incluidos: Costos directos de atención: Costos de medicamentos. Costos de procedimientos. Intervención y el comparador es de un año \r\ny medio aproximadamente (1,45) conun costo adicional de $12.439.243. Análisis de sensibilidad: La decisión \r\nno se mantiene para los escenarios que consideran: un costo del esquema ETC inferior o igual a $6.705.975, una probabilidad de muerte en ETC igual o menor al 5%, unos costos promedio de la atención de los EA crónicos de la estrategia ETC inferior es a $452.702 para todo el horizonte temporal, unos costos promedio de la atención de los EA crónicos de la estrategia TC superior es a $1.260.000 y una probabilidad de muerte en RA superior a 22,21% con el esquema TC. Conclusiones y discusión: La tecnología evaluada es menos efectiva y menos costosa que su comparador, y de acuerdo a las consultas dirigidas a los expertos ésta es identificada como esquema de tercera línea. Se pueden plantear nuevos estudios de costo efectividad que evalúen el esquema con everolimus como una alternativa de conversión ante la presencia de ciertos eventos adversos.

Análisis de costo efectividad de everolimusmás ciclosporina y prednisona comparado con micofenolato más ciclosporina y prednisona para la inmunosupresión de mantenimiento en eltrasplantecardíacoen Colombia / Cost-effectiveness analysis of everolimusmás ciclosporin and prednisone compared to mycophenolate plus ciclosporin and prednisone for maintenance immunosuppression in the cardiac transplant in Colombia

Problema de investigación: Calcular los costos y la efectividad esperados de everolimus más ciclosporina y corticosteroide (ECC) comparado con micofenolato más ciclosporina y corticoesteroide (MCC) para el tratamiento de pacientes colombianos, adultos, receptores de trasplante de corazón por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Tipo de evaluación económica Análisis de costo-efectividad. Población objetivo: Pacientes colombianos, adultos, receptores de trasplante de corazón por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Intervención y comparadores I: Everolimus más ciclosporina (dosis reducida) y corticosteroide (ECC). C: Micofenolato más ciclosporina (dosis estándar) y corticoesteroides (MCC). Horizonte temporal: Vital. Perspectiva Sistema General de Seguridad Social en Salud (SGSSS). Tasa de descuento: Se emplea una tasa de descuento común tanto para los costos como para los desenlaces en salud equivalente al 5 % anual. Adicionalmente, se realizan análisis de sensibilidad de 0 %, 3,5 %, 7 % y 12 %. Estructura del modelo: Modelo de Markov anidado en un árbol de decisiones. Fuentes de datos de efectividad y seguridad: Fueron empleados los recursos siguientes: el Reporte de efectividad y seguridad de las alternativas a evaluar previamente publicado por el IETS, los resultados de una búsqueda de literatura económica en las bases de datos del CRD y los de una búsqueda manual de literatura económica y clínica, además de la información obtenida en la consulta a expertos clínicos. Desenlaces y valoración: Años de vida ganados. Desenlaces y valoración: Años de vida ganados. Costos incluidos: Costos directos de atención: Costos de medicamentos, Costos de procedimiento. Fuentes de datos de costos SISMED: Medicamentos Manual tarifario ISS 2001: Procedimientos. Resultados del caso base: La administración del esquema ECC como inmunosupresión de mantenimiento para pacientes receptores de trasplante es una estrategia más costosa y menos efectiva, respecto al esquema MCC por lo que se considera una estrategia dominada. Análisis de sensibilidad: La intervención ECC deja de ser dominada sólo cuando la probabilidad de muerte en rechazo agudo con la otra estrategia es del 8,70% o superior, y cuando la probabilidad de presentar rechazo agudo es de 7,88% o inferior; el costo de la atención de los eventos adversos crónicos para la estrategia MCC y el costo del esquema EEC, son las variables respecto a las cuales el costo total \r\nparece tener mayor sensibilidad. La curva de aceptabilidad muestra que para el umbral considerado de 3 veces el PIB per cápita, el esquema con everolimus tiene una probabilidad de ser costo efectiva del 15,6%.\r\nConclusiones y discusión: En la práctica clínica actual, everolimus se administra como componente de los esquemas de inmunosupresión de mantenimiento sólo en situaciones particulares tales como terapia escalada en inmunosupresión (en caso de rechazo con terapia estándar), vasculopatía del injerto, disfunción renal o neoplasias. El esquema más usado en la práctica asistencial actual es el que incluye micofenolato más ciclosporina y prednisona (un corticosteroide), que es el indicado para todos los pacientes trasplantados. Los estudios clínicos desarrollados que han comparado estos dos esquemas \r\nconcluyen que tienen un perfil semejante de efectividad y seguridad y el acá desarrollado clasifica el esquema con everolimus como una estrategia dominada.(AU)

Análisis de costo efectividad de everolimus más ciclosporina y prednisona comparado con micofenolato más ciclosporina y prednisona para la inmunosupresión de mantenimiento en el trasplante renal en Colombia / Cost-effectiveness analysis of everolimus plus ciclosporin and prednisone compared to mycophenolate plus ciclosporin and prednisone for maintenance immunosuppression in renal transplantation in Colombia

Problema de investigación: Calcular los costos y la efectividad esperados del everolimus mas ciclosporina y corticosteroide (ECC) comparado con micofenolato mas ciclosporina y corticoesteroides (MCC) para el tratamiento de pacientes colombianos, adultos, receptores de trasplante de riñón por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Tipo de evaluación económica: Análisis de costo-efectividad. Población objetivo: Pacientes colombianos, adultos, receptores de trasplante de riñón por primera vez, que han iniciado la terapia de inducción de inmunosupresión y que se perfilan para el tratamiento de mantenimiento. Intervención y comparadores: I: Everolimus mas Ciclosporina (dosis reducida) y Corticosteroide (ECC). C: Micofenolato mas Ciclosporina (dosis estándar) y Corticoesteroides (MCC). Horizonte temporal: Vital. Perspectiva: Sistema General de Seguridad Social en Salud (SGSSS). Tasa de descuento: Se emplea una tasa de descuento común tanto a los costos como a los desenlaces en salud, equivalente al 5 % anual. Adicionalmente, se realizan análisis de sensibilidad de 0 %, 3,5 %, 7 % y 12 %. Estructura del modelo: Modelo de Markov anidado en un árbol de decisiones. Fuentes de datos de efectividad y seguridad. Fueron usados los recursos siguientes: el Reporte de efectividad y seguridad de las alternativas a evaluar previamente publicado por el IETS, los resultados de una búsqueda de literatura económica en las base de datos del CRD, de una búsqueda manual de literatura económica y clínica, y la información obtenida producto de la consulta a expertos clínicos. Desenlaces y\r\nvaloración: Años de vida ganados. Costos incluidos: Costos directos de atención: Costos de medicamentos\r\nCostos de procedimientos. Fuentes de datos de costos: SISMED: Medicamentos Manual tarifario ISS 2001: Procedimientos. Resultados del caso base: Los resultados del caso base para la administración del esquema ECC como inmunosupresión de mantenimiento para pacientes receptores de trasplante es una estrategia más costosa y más efectiva, respecto al esquema MCC; no obstante, si se asume que la disposición a pagar es 3 veces el PIB per cápita por un años de vida ganado, la estrategia ECC no es costo efectiva por superar dicho umbral. Análisis de sensibilidad: Este resultado se mantiene en todos los escenarios planteados excepto para los casos en los cuales la probabilidad de pérdida del injerto ante presencia de rechazo agudo en el esquema MCC toma valores superiores al 8%, cuando los costos del esquema de medicamentos ECC son inferiores a $4.083.749, y cuando la probabilidad de presentar eventos adversos crónicos con la estrategia ECC es inferior al 25%. Conclusiones y discusión: En la práctica clínica actual, everolimus se administra como componente de los esquemas de inmunosupresión de mantenimiento sólo en situaciones particulares como estrategia de conversión si se presenta toxicidad renal por ciclosporina, cáncer de piel u otro tipo de cáncer que se encuentra en riesgo de aumentar su tasa de crecimiento, o ante eventos como la hiperplasia gingival entre los más comunes. El esquema más usado en la práctica asistencial actual es el que incluye micofenolato más ciclosporina y prednisona, indicado para todos los pacientes trasplantados. Los estudios clínicos desarrollados que han comparado estos dos esquemas concluyen que tienen un perfil semejante de efectividad y seguridad y el acá desarrollado clasifica el esquema con everolimus como una estrategia no costo efectiva.

National Variation in Use of Immunosuppression for Kidney Transplantation: A Call for Evidence-Based Regimen Selection.

Immunosuppression management in kidney transplantation has evolved to include an increasingly diverse choice of medications. Although informed by patient and donor characteristics, choice of immunosuppression regimen varies widely across transplant programs. Using a novel database integrating national transplant registry and pharmacy fill records, immunosuppression use at 6-12 and 12-24 mo after transplant was evaluated for 22 453 patients transplanted in 249 U.S. programs in 2005-2010. Use of triple immunosuppression comprising tacrolimus, mycophenolic acid or azathioprine, and steroids varied widely (0-100% of patients per program), as did use of steroid-sparing regimens (0-77%), sirolimus-based regimens (0-100%) and cyclosporine-based regimens (0-78%). Use of triple therapy was more common in highly sensitized patients, women and recipients with dialysis duration >5 years. Sirolimus use appeared to diminish over the study period. Patient and donor characteristics explained only a limited amount of the observed variation in regimen use, whereas center choice explained 30-46% of the use of non-triple-therapy immunosuppression. The majority of patients who received triple-therapy (79%), cyclosporine-based (87.6%) and sirolimus-based (84.3%) regimens continued them in the second year after transplant. This population-based study of immunosuppression practice demonstrates substantial variation in center practice beyond that explained by differences in patient and donor characteristics.

Calcineurin and mTOR inhibitors have opposing effects on regulatory T cells while reducing regulatory B cell populations in kidney transplant recipients.

BACKGROUND: Regulatory B (Breg) and T (Treg) cells represent a biomarker for tolerance in transplant patients. Despite the importance of Treg and Breg in transplantation and the suggested crosstalk between both suppressive cell populations, little is known on how they are influenced by long-term immunosuppressive treatment. The aim of the present study was to investigate the effect of different immunosuppressive drugs used in routine clinical practice on Treg and Breg cell numbers. METHODS: Thirty-six kidney transplant recipients with stable graft function were recruited and classified according to their concomitant therapy: 22 patients received calcineurin inhibitors (CNI) and 14 patients received mammalian target of rapamycin (mTOR) inhibitors. A group of 8 healthy untreated subjects was included as control. Absolute numbers of peripheral blood-derived IL10-producing B cells (CD19(+)IL10(+)), CD19(+)CD24(hi)CD38(hi) transitional B cells and Treg cells (CD4(+)CD25(+)FOXP3(+)) were quantified in all KT patients and controls by flow cytometry. RESULTS: CD19(+)CD24(hi)CD38(hi) transitional B cells increased over time and seem to be related with long-term therapeutic graft survival irrespective of the treatment regimen. CNI and mTOR inhibitors significantly reduced numbers of Breg cells when compared with healthy individuals, whereas mTOR inhibitors expanded Treg cells in comparison with CNI drugs. CONCLUSIONS: Bridging the drug-mediated reduction of Breg cell numbers in vivo with the requirements of Breg cells for long-term transplant success remains an as yet unresolved task for therapeutic intervention. Further larger cohort studies that evaluate the effect of different treatment regimen on defined lymphocyte subpopulations are warranted.

[Pharmacogenetics: a promising tool to personalize immunosuppressive therapy in renal transplantation]. / Farmacogenetica: un possibile strumento per la personalizzazione della terapia immunosoppressiva nel trapianto renale.

Renal transplantation is the gold standard therapy for patients affected by end stage renal disease. It is a clinical condition characterized by severe biological/biochemical alterations that requires renal replacement therapy to ensure patients survival. In most cases, it is followed by a significant improvement of patients quality of life, reduction in medical expenses and prolongation of life. However, to reach these positive clinical effects, patients need to take several immunosuppressive medications (calcineurin inhibitors, mTOR inhibitors and antimetabolites) characterized by a narrow therapeutic index, that, in some cases, could cause important adverse effects. To avoid toxicities and adverse drug reactions, immunosuppressors should be correctly administered, according to the blood trough levels. Nevertheless, in most of the times, this methodology to adjust drug doses gives inadequate and non-reproducible results. Additionally, as largely described, inherited differences in drug metabolism and disposition and genetic variability in therapeutic targets (e.g. receptors) need to be taken into account because of their role in modulating drug effects and toxicities. Therefore, worldwide researchers are working together to identify biomarkers, useful to personalize therapy based on genetic characteristics of patients. In this context, we believe that the omics techniques could represent a future powerful instruments that, whether employed routinely, could help to reach this objective.

Cellular and molecular immune profiles in renal transplant recipients after conversion from tacrolimus to sirolimus.

Tacrolimus and sirolimus are commonly used maintenance immunosuppressants in kidney transplantation. As their effects on immune cells and allograft molecular profiles have not been elucidated, we characterized the effects of tacrolimus to sirolimus conversion on the frequency and function of T cells, and on graft molecular profiles. Samples from renal transplant patients in a randomized trial of 18 patients with late sirolimus conversion and 12 on tacrolimus maintenance were utilized. Peripheral blood was collected at 0, 6, 12, and 24 months post randomization, with T-cell subpopulations analyzed by flow cytometry and T-cell alloreactivity tested by IFN-γ ELISPOT. Graft biopsy samples obtained 24 months post randomization were used for gene expression analysis. Sirolimus conversion led to an increase in CD4(+)25(+++)Foxp3(+) regulatory T cells. While tacrolimus-maintained patients showed a decrease in indirect alloreactivity over time post transplant, sirolimus conversion increased indirect alloreactive T-cell frequencies compared with tacrolimus-maintained patients. No histological differences were found in graft biopsies, but molecular profiles showed activation of the antigen presentation, IL-12 signaling, oxidative stress, macrophage-derived production pathways, and increased inflammatory and immune response in sirolimus-converted patients. Thus, chronic immune alterations are induced after sirolimus conversion. Despite the molecular profile being favorable to calcineurin inhibitor-based regimen, there was no impact in renal function over 30 months of follow-up.

Transplantation: rituximab induction for prevention of HLA-antibody rebound.

Desensitization therapy enables HLA-incompatible transplantation. However, desensitized patients have an increased risk of antibody-mediated rejection, and the presence of donor-specific antibodies (DSAs) is associated with poor outcomes. A new study has assessed the effect of rituximab induction on DSA production in kidney transplant recipients with high immunological risk.

Pharmacogenetics and immunosuppressive drugs in solid organ transplantation.

The transplantation literature includes numerous papers that report associations between polymorphisms in genes encoding metabolizing enzymes and drug transporters, and pharmacokinetic data on immunosuppressive drugs. Most of these studies are retrospective in design, and although a substantial number report significant associations, pharmacogenetic tests are hardly used in clinical practice. One of the reasons for this poor implementation is the current lack of evidence of improved clinical outcome with pharmacogenetic testing. Furthermore, with efficient therapeutic drug monitoring it is possible to rapidly correct for the effect of genotypic deviations on pharmacokinetics, thereby decreasing the utility of genotype-based dosing. The future of pharmacogenetics will be in treatment models in which patient characteristics are combined with data on polymorphisms in multiple genes. These models should focus on pharmacodynamic parameters, variations in the expression of drug transporter proteins, and predictors of toxicity. Such models will provide more information than the relatively small candidate gene studies performed so far. For implementation of these models into clinical practice, linkage of genotype data to medication prescription systems within electronic health records will be crucial.

New nucleos(t)ide analogue monoprophylaxis after cessation of hepatitis B immunoglobulin is effective against hepatitis B recurrence.

New nucleos(t)ide agents (NAs) [entecavir (ETV) and tenofovir (TDF)] have made hepatitis B immunoglobulin (HBIG)-sparing protocols an attractive approach against hepatitis B virus (HBV) recurrence after liver transplantation (LT). Twenty-eight patients transplanted for HBV cirrhosis in our centre were prospectively evaluated. After LT, each patient received HBIG (1000 IU IM/day for 7 days and then monthly for 6 months) plus ETV or TDF and then continued with ETV or TDF monoprophylaxis. All patients had undetectable HBV DNA at the time of LT, and they were followed up with laboratory tests including glomerular filtration rate (GFR) after LT. All patients (11 under ETV and 17 under TDF) remained HBsAg/HBV DNA negative during the follow-up period [median: 21 (range 9-43) months]. GFR was not different between TDF and ETV groups of patients at 6 and 12 months and last follow-up (P value >0.05 for all comparisons). The two groups of patients were similar regarding their ratio of maximum rate of tubular phosphate reabsorption to the GFR (TmP/GFR). In conclusion, in this prospective study, we showed for the first time that maintenance therapy with ETV or TDF monoprophylaxis after 6 months of low-dose HBIG plus ETV or TDF after LT is highly effective and safe.