Mechanistic insights into achievement of cardiac allograft long-term survival by treatment with immature dendritic cells and sub-dose sirolimus

Dendritic cell sphingosine 1-phosphate receptor-3 regulates Th1-Th2 polarity in kidney ischemia-reperfusion injury

Dendritic cells (DCs) are central to innate and adaptive immunity of early kidney ischemia-reperfusion injury (IRI), and strategies to alter DC function may provide new therapeutic opportunities. Sphingosine 1-phosphate (S1P) modulates immunity through binding to its receptors (S1P1-5), and protection from kidney IRI occurs in S1P3-deficient mice. Through a series of experiments we determined that this protective effect was owing in part to differences between S1P3-sufficient and -deficient DCs. Mice lacking S1P3 on bone marrow cells were protected from IRI, and S1P3-deficient DCs displayed an immature phenotype. Wild-type (WT) but not S1P3-deficient DCs injected into mice depleted of DCs prior to kidney IR reconstituted injury. Adoptive transfer (i.e., i.v. injection) of glycolipid (Ag)-loaded WT but not S1P3-deficient DCs into WT mice exacerbated IRI, suggesting that WT but not S1P3-deficient DCs activated NKT cells. Whereas WT DC transfers activated the Th1/IFN-γ pathway, S1P3-deficient DCs activated the Th2/IL-4 pathway, and an IL-4-blocking Ab reversed protection from IRI, supporting the concept that IL-4 mediates the protective effect of S1P3-deficient DCs. Administration of S1P3-deficient DCs 7 d prior to or 3 h after IRI protected mice from IRI and suggests their potential use in cell-based therapy. We conclude that absence of DC S1P3 prevents DC maturation and promotes a Th2/IL-4 response. These findings highlight the importance of DC S1P3 in modulating NKT cell function and IRI and support development of selective S1P3 antagonists for tolerizing DCs for cell-based therapy or for systemic administration for the prevention and treatment of IRI and autoimmune diseases.

Adoptive transfusion of tolerance dendritic cells prolongs the survival of cardiac allograft: a systematic review of 44 basic studies in mice

BACKGROUND AND OBJECTIVE

Tolerogenic DCs (Tol-DCs), a group of cells with imDC phenotype, can stably induce T cells low-reactivity and immune tolerance. We systematically reviewed the adoptive transfusion of Tol-DCs induced by different ways to prolong cardiac allograft survival and its possible mechanism.

METHOD

MEDLINE (1966 to March 2011), EMbase (1980 to March 2011), and ISI (inception to March 2011) were searched for identification of relevant studies. We used allogeneic heart graft survival time as endpoint outcome to analyze the effect of adoptive transfusion of Tol-DC on cardiac allograft. By integrating studies' information, we summarized the mechanisms of Tol-DC in prolonging cardiac grafts.

RESULTS

Four methods were used to induce Tol-DC in all of the 44 included studies including gene-modified, drug-intervened, cytokine-induced, and other-derived (liver-derived & spleen-derived) DCs. The results showed that all types of Tol-DC can effectively prolong graft survival, and the average extension of graft survival time for each group was as follows: 22.02 ± 21.9 days (3.2 folds to control group) in the gene modified group, 25.94 ± 16.9 days (4.3 folds) in the drug-intervened groups, 9.00 ± 8.13 days (1.9 folds) in the cytokine-induced group, and 10.69 ± 9.94 days (2.1 folds) in the other-derived group. The main mechanisms of Tol-DCs to prolong graft survival were as follows: (1) induceT-cell hyporeactivity (detected by MLR); (2) reduce the effect of cytotoxic lymphocyte (CTL); (3) promote Th2 differentiation; (4) induce Treg; (5) induce chimerism.

CONCLUSION

For fully MHC mismatched allogeneic heart transplant recipients of inbred mouse, adoptive transfusion of Tol-DC, which can be gene-modified, drug-intervened, cytokine-induced, spleen-derived or liver-derived, can clearly prolong the survival of cardiac allograft or induce immune tolerance. Gene-modified and drug-induced Tol-DC can prolong graft survival most obviously. Having better reliability and stability than drug-induction, gene-modification is the best way to induce Tol-DCs at present. One-time intravenous infusion of 2 × 10(6) Tol-DC is a simple and feasible way to induce long-term graft survival. Multiple infusions will prolong it but increase the risk and cost. Adoptive transfusion of Tol-DC in conjunction with immunosuppressive agents may also prolong the graft survival time.

The effect of sirolimus- or cyclosporine-based immunosuppression effects on T-cell subsets in vivo

While sirolimus (SRL) is thought to be a non-nephrotoxic agent, cyclosporine A (CsA) toxicity is a serious problem in kidney transplantation. We compared the effects of the two drugs on T-helper (Th) subsets in kidney transplant patients. We examined 24 first cadaver kidney recipients equally randomized to receive SRL/mycophenolate mofetil (MMF)/methylprednisolone (MP), or cyclosporine with either MMF or MP. The Th1 and Th2 subsets in peripheral blood were separated based on their production of interferon-gamma (INFgamma) or interleukin (IL)-4/IL-5. The lymphocytes were stimulated with phytohemoagglutinin or with allogenic CD3-depeted and irradiated antigen-presenting cells. Furthermore, the conversion potential of Th0 to Th1 was determined by measuring IL-12 and IL-18 levels after lipopolysaccharide challenge. When peripheral blood lymphocytes taken from SRL-treated patients were stimulated by phytohemoagglutinin, there were significantly lower INFgamma-producing cells compared with the lymphocytes taken from patients treated with CsA. The number of IL-4/IL-5-producing cells did not differ among the patient groups. Release of IL-12 but not IL-18 from peripheral lymphocytes following treatment with lipopolysaccharide was significantly lower in the SRL-treated patients. These results show that compared with CsA, SRL caused a significant decrease in the Th1 lymphocyte subset associated with a significant reduction of IL-12 release.