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.

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.

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.

Sibling donor and recipient immune modulation with atorvastatin for the prophylaxis of acute graft-versus-host disease.

PURPOSE: Graft-versus-host disease (GVHD) is major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). Atorvastatin is a potent immunomodulatory agent that holds promise as a novel and safe agent for acute GVHD prophylaxis. PATIENTS AND METHODS: We conducted a phase II trial to evaluate the safety and efficacy of atorvastatin administration for GVHD prophylaxis in both adult donors and recipients of matched sibling allogeneic HCT. Atorvastatin (40 mg per day orally) was administered to sibling donors, starting 14 to 28 days before the anticipated first day of stem-cell collection. In HCT recipients (n = 30), GVHD prophylaxis consisted of tacrolimus, short-course methotrexate, and atorvastatin (40 mg per day orally). RESULTS: Atorvastatin administration in healthy donors and recipients was not associated with any grade 3 to 4 adverse events. Cumulative incidence rates of grade 2 to 4 acute GVHD at days +100 and +180 were 3.3% (95% CI, 0.2% to 14.8%) and 11.1% (95% CI, 2.7% to 26.4%), respectively. One-year cumulative incidence of chronic GVHD was 52.3% (95% CI, 27.6% to 72.1%). Viral and fungal infections were infrequent. One-year cumulative incidences of nonrelapse mortality and relapse were 9.8% (95% CI, 1.4% to 28%) and 25.4% (95% CI, 10.9% to 42.9%), respectively. One-year overall survival and progression-free survival were 74% (95% CI, 58% to 96%) and 65% (95% CI, 48% to 87%), respectively. Compared with baseline, atorvastatin administration in sibling donors was associated with a trend toward increased mean plasma interleukin-10 concentrations (5.6 v 7.1 pg/mL; P = .06). CONCLUSION: A novel two-pronged strategy of atorvastatin administration in both donors and recipients of matched sibling allogeneic HCT seems to be a feasible, safe, and potentially effective strategy to prevent acute GVHD.

Fundamental immunology of skin transplantation and key strategies for tolerance induction.

Transplantation of allogeneic or xenogeneic skin grafts can evoke strong immune responses that lead to acute rejection of the graft tissues. In this process, donor-derived dendritic cells play crucial roles in the triggering of such immune responses. Both the innate and acquired host immune systems participate in graft rejection. At present, the rejection of skin grafts cannot be well-controlled by ordinary systemic immunosuppression therapy. Although several strategies for the long-term survival of allogeneic or xenogeneic skin grafts have been demonstrated in animal models, the induction of long-term tolerance to skin grafts is still a great challenge in clinical settings. In this article, we review the progress in the understanding of immune responses to skin grafts and discuss the possible methods that can decrease the immunogenicity of graft tissues and improve the survival of skin grafts, especially those included in preoperative pre-treatments.

Characterization of granulocyte colony stimulating factor for in vitro induction of regulatory T cells for cellular immune intervention in transplant medicine.

OBJECTIVES: The application of regulatory T cells in the field of solid-organ and hematopoietic stem cell transplantation is under investigation to develop novel cellular strategies for tolerance induction. Establishing in vitro procedures to induce and expand regulatory T cells seeks to overcome the limiting small number of this rare T cell population. The present study is based on growing evidence that granulocyte colony stimulating factor exerts immune regulatory function in the adaptive immune system and may induce regulatory T cells in vivo. MATERIALS AND METHODS: We analyzed the effect of recombinant granulocyte colony stimulating factor to directly convert CD4+CD25- T cells into regulatory T cells in vitro. Marker molecules were analyzed by quantitative reverse transcriptase-polymerase chain reaction and fluorescent-activated cell sorter analyses. Functional assays were performed to investigate the suppressive capacity of granulocyte colony stimulating factor stimulated T cells. RESULTS: Kinetic analyses of Foxp3 gene expression uncovered increased levels early after in vitro stimulation with granulocyte colony stimulating factor. However, protein analyses for the master transcription factor Foxp3 and other regulatory T cells revealed that granulocyte colony stimulating factor did not directly induce a regulatory T cell phenotype. Moreover, functional analyses demonstrated that granulocyte colony stimulating factor stimulation in vitro does not result in a suppressive, immune regulatory T cell population. CONCLUSIONS: Granulocyte colony stimulating factor does not induce regulatory T cells with a specific phenotype and suppressive potency in vitro. Therefore, granulocyte colony stimulating factor does not qualify for developing protocols aimed at higher regulatory T cell numbers for adoptive transfer strategies in solid organ and hematopoietic stem cell transplantation.

Systemic immunoregulatory and proteogenomic effects of tacrolimus to sirolimus conversion in liver transplant recipients.

UNLABELLED: Immunosuppression (IS) withdrawal from calcineurin inhibitors is only possible in ≈ 20% of liver transplant recipients. However, mammalian target of rapamycin inhibitors (e.g., sirolimus; SRL) appear to be more immunoregulatory and might promote a tolerant state for withdrawal. Our aim was to determine whether systemic (i.e., blood, marrow, and allograft) signatures of immunoregulation are promoted by conversion from tacrolimus (TAC) to SRL. We therefore performed the following serial assays before and after SRL conversion in liver transplant recipients to test for enhanced markers of immunoregulation: (1) flow-cytometry immunophenotyping of peripheral blood mononuclear cells (PBMCs) and bone marrow aspirates for regulatory T cells (Tregs) (e.g., CD4(+) CD25(+++) FOXP3(+) ) and regulatory dendritic cells (DCregs) (immunoglobulin-like transcript 3(+) /4(+) ); (2) liver biopsy immunohistochemical staining (e.g., FOXP3:CD3 and CD4:CD8 ratios) and immunophenotyping of biopsy-derived Tregs after growth in culture; (3) effects of pre- versus postconversion sera on Treg generation in mixed lymphocyte reactions; (4) peripheral blood nonspecific CD4 responses; and (5) peripheral blood gene transcripts and proteomic profiles. We successfully converted 20 nonimmune, nonviremic recipients (age, 57.2 ± 8.0; 3.5 ± 2.1 years post-liver transplantation) from TAC to SRL for renal dysfunction. Our results demonstrated significant increases in Tregs in PBMCs and marrow and DCregs in PBMCs (P < 0.01) after conversion. In biopsy staining, FOXP3:CD3 and CD4:CD8 ratios were significantly higher after conversion and a number of biopsy cultures developed new or higher FOXP3(+) cell growth. Nonspecific CD4 responses did not change. Both pre- and postconversion sera inhibited mixed lymphocyte reactions, although only TAC sera suppressed Treg generation. Finally, 289 novel genes and 22 proteins, several important in immunoregulatory pathways, were expressed after conversion. CONCLUSIONS: TAC to SRL conversion increases systemic Tregs, DCregs, and immunoregulatory proteogenomic signatures in liver transplant recipients and may therefore facilitate IS minimization or withdrawal.

Potential applications of vasoactive intestinal Peptide-based therapies on transplantation.

Vasoactive intestinal peptide (VIP) is a well-known immunoregulatory neuropeptide produced by the immune system in response to inflammation, autoimmunity or alloantigens as a natural endogenous mechanism of induction of tolerance. VIP has been proven therapeutically effective in various experimental models of autoimmune disorders and recently in human sarcoidosis. Numerous studies clearly show that VIP exerts its immunomodulatory effects by downregulating both inflammatory and Th1 responses. Recent evidences suggest that new actors enter in scene to play a role in this scenario of tolerance. By inducing antigen-specific regulatory T cells and tolerogenic dendritic cells, VIP seems to reinforce/reinstall immune tolerance, especially under autoimmune conditions. Transplantation is also a condition where VIP-related therapies emerge as promising tools for clinical application. Induction of alloantigen-specific tolerance is critical to achieve organ transplant tolerance and to avoid graft-versus-host responses following allogeneic hematopoietic transplantation. This review will focus on describing the capacity of VIP to induce suppressive/regulatory immune cells and how we can manage this cell-based therapeutic strategy to induce transplant tolerance in subjects free of immunosuppressive drugs.

Methylprednisolone treatment increases the proportion of the highly suppressive HLA-DR(+)-Treg-cells in transplanted patients.

Methylprednisolone is widely used to improve immune suppression in transplanted patients threatened by acute rejection. Recently, we showed that the suppressive activity of a Treg cell population depends decisively on their percentage of highly suppressive HLA-DR(high+)-Treg cells, which are strongly reduced in rejecting transplant patients. In order to examine whether the composition of the total CD4(+)CD127(low+/-)FoxP3(+)-Treg cell pool with different Treg-subsets (DR(high+)CD45RA(-)-Tregs, DR(low+)CD45RA(-)-Tregs, DR(-)CD45RA(-)-Tregs, DR(-)CD45RA(+)-Tregs) is affected by methylprednisolone bolus therapy we compared the percentages of these four different Treg cell subsets in transplant patients with biopsy proven rejection before and after steroid bolus therapy (n=23). In patients treated with steroid bolus therapy, the percentage of the naïve DR(-)CD45RA(+)-Tregs was significantly decreased, whereas the percentage of the DR(+)CD45RA(-)-Tregs was significantly increased. By that, the strongest increase was detected for the most suppressive DR(high+)CD45RA(-)-Tregs. However, these effects were only temporarily and closely associated to the duration of the bolus therapy. Our results suggest that besides various anti-inflammatory effects on cells of the adaptive and innate immune system, methylprednisolone also has the capacity to enhance the suppressive activity of the total Treg cell pool by increasing its percentage of highly differentiated and highly suppressive DR(high+)CD45RA(-)-Tregs.

Feasibility of localized immunosuppression: 3. Preliminary evaluation of organosilicone constructs designed for sustained drug release in a cell transplant environment using dexamethasone.

As part of our ongoing effort to develop biohybrid devices for pancreatic islet transplantation, we are interested in establishing the feasibility of a localized immune-suppressive approach to avoid or minimize the undesirable side effects of existing systemic treatments. Since biohybrid devices can also incorporate biocompatible scaffold constructs to provide a support environment for the transplanted cells that enhances their engraftment and long-term function, we are particularly interested in an approach that would use the same three-dimensional construct, or part of the same construct, to also provide sustained release of therapeutic agents to modulate the inflammatory and immune responses locally. Within this framework, here, we report preliminary results obtained during the investigation of the suitability of organosilicone constructs for providing sustained localized drug release using small, matrix-type polydimethylsiloxane (PDMS) disks and dexamethasone as a model hydrophobic drug. Following a short burst, long-term steady sustained release was observed under in vitro conditions at levels of 0.1-0.5 microg/day/disk with a profile in excellent agreement with that predicted by the Higuchi equation. To verify that therapeutic levels can be achieved, suppression of LPS-induced activation has been shown in THP-1 cells with disks that have been pre-soaked for up to 28 days. These preliminary results prove the feasibility of this approach where an integral part of the biomaterial construct used to enhance cell engraftment and long-term function also serves to provide sustained local drug release.

Impact of HDAC inhibitors on dendritic cell functions.

Histone deacetylase inhibitors are presently used in the routine clinic treatment against cancers. Recent data have established that some of these treatments have potent anti-inflammatory or immunomodulatory effects at noncytotoxic doses that might be of benefit in immuno-inflammatory disorders or post-transplantation. At least some of these effects result from the ability of histone deacetylase inhibitors to modulate the immune system. Dendritic cells are professional antigen presenting cells that play a major role in this immune system. Data summarized in this review brings some novel information on the impact of histone deacetylase inhibitors on dendritic cell functions, which may have broader implications for immunotherapeutic strategies.

Mitomycin-C-treated peripheral blood mononuclear cells (PBMCs) prolong allograft survival in composite tissue allotransplantation.

BACKGROUND: Composite tissue allotransplantation (CTA) was introduced as a potential treatment for complex reconstructive procedures and has become a clinical reality. Hand and face transplantation, the most widely recognized forms of CTA, have intensified immunological research in this emerging field of transplantation. Mitomycin C (MMC) is an alkylating agent that suppresses allogeneic T-cell responses. MMC-treated dendritic cells/PBMCs have been shown to induce donor-specific tolerance in solid organ allograft transplantations. METHODS: Fully mismatched rats were used as hind limb donors [Lewis (RT1(1))] and recipients [Brown-Norway (RT1(n))]. Fifty-five allogeneic hind limb transplantations were accomplished in six groups. Group A (n = 10) received donor-derived MMC-treated PBMCs on transplantation day. Group B (n = 10) rats received no immunosuppression, group C (n = 10) received FK506 and prednisolon, group D consisted in isograft transplantation without immunosuppression, group E (n = 10) received non-treated PBMCs, and group F (n = 5) received PBS without any donor-derived cells. Rejection was assessed clinically and histologically. RESULTS: In group A, the survival times of the allografts were prolonged to an average of 8.0 d. Rejection was significantly delayed compared with the averages of the corresponding control groups B, E, and F (5.5, 5.9, and 5.8 d). No rejection was seen in control groups C and D. CONCLUSION: These results demonstrate that MMC-treated donor PBMCs significantly prolong allograft survival when administered systemically on the day of transplantation. However, the immunomodulatory effect is relatively modest with further research being required to clarify dose-effect relations, cell characteristics, and an optimized mechanism and timing for cell application.