New advances in antirejection therapy

Update on Immunosuppressive Drugs Used in Solid-Organ Transplantation and Their Nutrition Implications

The success of solid organ transplantation rests heavily on the major advances in immunosuppressive therapy. The early years of organ transplantation were plagued with high failure rates and frequent episodes of acute rejection. With the introduction of improved immunosuppressive agents, successful organ transplantation has become the norm. The emphasis of immunosuppressive therapy has shifted from preventing rejection to balancing acceptable rates of rejection with moderation in adverse effects of the immunosuppressive agents. Among the many possible adverse effects of immunosuppressive therapy is the potential for these agents to affect the nutrition status of the transplant recipient. Given the fact that many patients undergoing transplantation are catabolic and nutritionally vulnerable, it is particularly important for those involved in the care of these patients to be familiar with the nutrition implications of immunosuppressive drugs. In this article, we review the different classes of immunosuppressive medications used in transplantation and emphasize their interactions with the nutrition status of the transplant recipient.

Heart Transplantation-The Pediatric Cardiac Critical Care Perspective

OBJECTIVES

Although there have been tremendous advancements in the care of severe pediatric cardiovascular disease, heart transplantation remains the standard therapy for end-stage heart disease in children. As such, these patients comprise an important and often complex subset of patients in the ICU. The purpose of this article is to review the causes and management of allograft dysfunction and the medications used in the transplant population.

DATA SOURCES

MEDLINE, PubMed, and Cochrane Database of systemic reviews.

CONCLUSIONS

Pediatric heart transplant recipients represent a complex group of patients that frequently require critical care. Their immunosuppressive medications, while being vital to maintenance of allograft function, are associated with significant short- and long-term complications. Graft dysfunction can occur from a variety of etiologies at different times following transplantation and remains a major limitation to long-term posttransplant survival.

The spectrum of nonadherence with medication in heart, liver, and lung transplant patients assessed in various ways

Adherence to medication regimes is crucial for transplant patients. Addressing methodological limitations and gaps in the literature, we studied: (i) the prevalence of nonadherence (NA) with immunosuppression (IS) using various measurement methods, (ii) NA prevalence regarding intake and timing, (iii) changes in NA over time, (iv) differences in NA across organ transplant populations, (v) NA regarding co-medication. Using a descriptive, prospective, comparative design over 3 months, we included convenience samples of adult heart (n=79), liver (n=55), and lung (n=104) transplant patients. NA with IS was measured using self-report, collateral report, blood assay, electronic monitoring (Helping Hand™ , Bang and Olufsen Medicom, Denmark), and their combinations. In the overall sample, depending on the method used, IS NA ranged from 23.9% to 70.0%. For co-medication, the overall NA rate was 30.1% using self-report. Nonadherence rates remained stable over time. At inclusion, significant NA differences between organ groups were reported via self- and collateral report; lung transplant patients were less adherent than heart or liver transplant recipients, both to IS and to co-medication.

IL2-caspase3 chimeric protein controls lymphocyte reactivity by targeted apoptosis, leading to amelioration of experimental autoimmune encephalomyelitis

IL2-caspase3 chimeric protein was designed to target and kill cells expressing the high affinity IL-2 receptor. Its effects on lymphocyte reactivity and on experimental autoimmune encephalomyelitis (EAE), a T-cell mediated disease, were tested in this study. Our data show that IL2-caspase3 promoted cell specific apoptosis both in vitro and in vivo. Cell lines preferentially expressing the IL-2R alpha chain and encephalitogenic lymphocytes derived from EAE-induced mice were highly sensitive to the chimeras' activity. This was demonstrated by increased DNA fragmentation and annexin labeling together with reduced specific T-cell proliferation in response to IL2-casepase3 treatment. Furthermore, IL2-caspase3 treatment of EAE-induced mice caused a significant delay in disease onset together with a reduction in disease burden. The efficacy of IL2-caspase3 treatment was dependent on the time at which treatment begun, with the chimera ameliorating EAE only when administered at maximal activation of peripheral lymphocytes. According to our findings we suggest that the chimeric protein IL2-caspase3 may provide a novel approach for the treatment of a variety of autoimmune disorders, such as multiple sclerosis, as well as for other pathological conditions that involve uncontrolled expansion of activated T cells.

Prolongation of cardiac allograft survival by rapamycin and the invariant natural killer T cell glycolipid agonist OCH

BACKGROUND

Invariant natural killer T (iNKT) cells are glycolipid-responsive cells with potent immunomodulatory properties. Although iNKT cells have been implicated in cardiac allograft tolerance, whether in vivo triggering of iNKT cells with Th2-promoting glycolipids offers a therapeutic benefit in heart transplantation remains unexplored.

METHODS

C3H (H-2k) hearts were transplanted into C57BL/6 (H-2b) mice. The recipients were left untreated or received the Th2-promoting iNKT cell agonist OCH, the antirejection agent rapamycin, or both. Allografts were recovered on postoperative day 8 or at endpoint, stained with hematoxylin-eosin, and analyzed for intragraft transcript levels of effector cytokines and iNKT cells' invariant T-cell receptor segment Valpha14-Jalpha18. The presence of circulating alloantibodies was assessed in recipients' sera at similar time points. A second fully mismatched cardiac allograft model (BALB/c-to-C57BL/6) was used to further validate the efficacy of our treatment regimens.

RESULTS

Combination immunotherapy with OCH and rapamycin significantly enhanced C3H allograft survival and led to nearly normal graft histology with minimal vascular changes and mononuclear cell infiltration, and an almost normal IgG1:IgG2a ratio in recipients' sera. These were accompanied by elevated intragraft mRNA levels of interleukin (IL)-4, and to a lesser extent IL-10 and IL-13, and high transcript levels of Valpha14-Jalpha18 T-cell receptor gene segment. Furthermore, when used alone or together with rapamycin, OCH delayed allograft rejection in our BALB/c-to-C57BL/6 model.

CONCLUSIONS

In vivo administration of OCH may deviate alloimmune responses towards a Th2 phenotype and prolong allograft survival. Select iNKT cell glycolipid agonists can therefore be used in monotherapy or combination immunotherapy of transplant rejection.

Rapamycin modulates the maturation of rat bone marrow-derived dendritic cells

The purpose of the study was to observe the effect of rapamycin (RAPA) on the differentiation and maturation of rat bone marrow-derived dendritic cells (BMDCs) in vitro. BMDCs from Wistar rats were cultured with granulocyte-macrophage colony-stimulating factor plus interleukin-4 in the presence or absence of RAPA (20 ng/mL), and stimulated with lipopolysaccharide (LPS) for 24 h before cells and supernatants were collected. Surface phenotype of BMDCs was flow-cytometrically detected to determine the expression of maturation markers, MHC class II and CD86. Supernatants were analyzed for the production of IL-12 and IFN-gamma cytokines by using ELISA. BMDCs were co-cultured with T cells from Lewis rats and mixed lymphocyte reaction was assessed by MTT method. The morphology of BMDCs stimulated with LPS remained immature after RAPA pretreatment. RAPA significantly decreased the CD86 expression, impaired the IL-12 and IFN-gamma production of BMDCs stimulated with LPS, and inhibited the proliferation of allogeneic T cells. In conclusion, RAPA can inhibit the maturation of BMDCs stimulated with LPS in terms of the morphology, surface phenotype, cytokine production, and ability of BMDCs to stimulate the proliferation of allogeneic T cells in vitro.