Mechanism of immune hyporesponsiveness induced by recipient- derived immature dendritic cells in liver transplantation rat

Effects of IL-10- and FasL-overexpressing dendritic cells on liver transplantation tolerance in a heterotopic liver transplantation rat model

Acute rejection is the major determinant for the long-term survival of donor liver after liver transplantation (LT). The aim of this study was to examine the therapeutic potential of interleukin (IL)-10-FasL-overexpressing immature dendritic cells (imDCs) to induce local immunosuppression in liver grafts. imDCs derived from donors were transduced by lentiviral vectors expressing human IL-10 and/or Fas ligand (FasL) gene(s), and the expression of surface molecules and the ability to induce T-cell proliferation were measured. imDCs were intraperitoneally injected into recipient rats as a model of LT to examine the rejection grade [Banff rejection activity index (RAI)], liver functions [Alanine aminotransferase, Aspartate aminotransferase (AST) and total bilirubin (TBIL)] and post-transplant survival. IL-10 and FasL co-transduction of imDCs induced a greater reduction in CD80, CD86 and major histocompatibility complex class II (MHC II) expression, as well as T-cell proliferation, but increased levels of IL-10 and FasL in culture supernatants compared with mono-transduced or untransduced imDCs (P < 0.05). The infusion of co-transduced imDCs in LT recipients reduced RAI scores, decreased plasma AST and TBIL, and prolonged survival compared with mono-transduced or untransduced imDC-treated liver allografts. These findings demonstrated that the transfusion of IL-10-FasL/imDCs enhanced immune tolerance and prolonged the survival of liver allografts after LT. The immunomodulatory activity of IL-10- and FasL-modified imDCs might be a new therapeutic approach to prevent organ rejection in clinical transplantation.

Harnessing the properties of dendritic cells in the pursuit of immunological tolerance

The acquisition of self-perpetuating, immunological tolerance specific for graft alloantigens has long been described as the "holy grail" of clinical transplantation. By removing the need for life-long immunosuppression following engraftment, the adverse consequences of immunosuppressive regimens, including chronic infections and malignancy, may be avoided. Furthermore, autoimmune diseases and allergy are, by definition, driven by aberrant immunological responses to ordinarily innocuous antigens. The re-establishment of permanent tolerance towards instigating antigens may, therefore, provide a cure to these common diseases. Whilst various cell types exhibiting a tolerogenic phenotype have been proposed for such a task, tolerogenic dendritic cells (tol-DCs) are exquisitely adapted for antigen presentation and interact with many facets of the immune system: as such, they are attractive candidates for use in strategies for immune intervention. We review here our current understanding of tol-DC mediated induction and maintenance of immunological tolerance. Additionally, we discuss recent in vitro findings from animal models and clinical trials of tol-DC immunotherapy in the setting of transplantation, autoimmunity and allergy which highlight their promising therapeutic potential, and speculate how tol-DC therapy may be developed in the future.

Effects of Adoptive Transfer of Tolerogenic Dendritic Cells on Allograft Survival in Organ Transplantation Models: An Overview of Systematic Reviews

Objective. To dissect the efficacy of Tol-DC therapy with or without IS in multiple animal models of transplantation. Methods and Results. PubMed, Medline, Embase, and the Cochrane Library were searched for reviews published up to April 2015. Six systematic reviews and a total of 61 articles were finally included. Data were grouped by organ transplantation models and applied to meta-analysis. Our meta-analysis shows that Tol-DC therapy successfully prolonged allograft survival to varying extents in all except the islet transplantation models and with IS drugs further prolonged the survival of heart, skin, and islet allografts in mice, but not of heart allografts in rats. Compared with IS drugs alone, Tol-DC therapy with IS extended islet allograft survival in rats but failed to influence the survival of skin, small intestine, and heart allografts in rats or of heart and skin allografts in mice. Conclusion. Tol-DC therapy significantly prolonged multiple allograft survival and further prolonged survival with IS. However, standardized protocols for modification of Tol-DC should be established before its application in clinic.

Changes in the cytokine expression of peripheral Treg and Th17 cells in children with rotavirus enteritis

The aim of the present study was to investigate the changes in the cytokine expression of peripheral regulatory T cells (Treg) and T helper 17 (Th17) cells in children with rotavirus (RV) enteritis. In total, 102 children with RV enteritis were recruited for the observation group, while 30 healthy cases were included in the control group. Peripheral blood samples were collected from the individuals in the two groups, after which flow cytometry was conducted to detect the proportion of Treg and Th17 cells. In addition, ELISA was used to determine the levels of the cytokines, interleukin (IL)-10, transforming growth factor (TGF)-β, IL-17 and IL-6. When compared with the control group, the proportion of Treg cells and level of TGF-β in the peripheral blood of the children with RV enteritis were significantly decreased (P<0.05); however, the proportion of Th17 cells and the serum levels of IL-17 and IL-6 in the peripheral blood of children with RV enteritis were significantly increased (P<0.05). In conclusion, the present study identified an imbalance in the proportion of peripheral blood Treg/Th17 cells, and subsequently in the expression of cytokines, in children with RV enteritis. Thus, detecting the proportion of peripheral blood Treg/Th17 cells in children with RV enteritis, or the changes in the levels of serum cytokines, is of clinical significance for further investigation into the pathogenesis of RV enteritis.

Adoptive transfusion of tolerogenic dendritic cells prolongs the survival of liver allograft: a systematic review

OBJECTIVES

To systematically review the effects of tolerogenic dendritic cells (Tol-DCs) induced by different methods on liver transplantation and their possible mechanisms of action.

METHODS

PubMed and EMbase were searched for relevant articles through 31 December 2013. The effects of Tol-DCs on liver allograft survival were semiquantitatively evaluated, and the possible mechanisms by which Tol-DCs prolong graft survival were analyzed.

RESULTS

Seven articles were included, and classified according to methods of induction, sources, and methods of infusing Tol-DCs. Tol-DCs induced from immature DCs (imDCs), with cytokines, and by gene modification induced liver transplant tolerance for 33.1 ± 32.5 days (2.7-fold vs. control), 26.17 ± 16.20 days (1.8-fold vs. control), and 11.7 ± 1.6 days (2.3-fold vs. control), respectively. DCs derived from recipient bone marrow, donor bone marrow, and donor spleen induced liver transplant tolerance for 51.0 ± 0.0 days (5.9-fold vs. control), 21.4 ± 26.8 days (2.4-fold vs. control), and 15.0 ± 0.0 days (2.3-fold vs. control), respectively. The primary mechanisms by which Tol-DCs induce liver transplant tolerance were the induction of T-cell hyporeactivity and Th2 differentiation.

CONCLUSIONS

Tol-DCs induced by three different methods could extend liver allograft survival, with imDCs showing optimal results. The optimal infusion method was intravenous injection of 1-2 × 10(6) Tol-DC, similar to findings in renal transplantation. Tol-DCs prolonged liver transplant tolerance more than renal transplant tolerance.