A novel immunosuppressant, IR-1116, which has a different biological mechanism from that of cyclosporine A

Synthesis of a 2,4,6-trisubstituted 5-cyano-pyrimidine library and evaluation of its immunosuppressive activity in a Mixed Lymphocyte Reaction assay

A series of novel pyrimidine analogues were synthesized and evaluated for immunosuppressive activity in the Mixed Lymphocyte Reaction assay, which is well-known as the in vitro model for in vivo rejection after organ transplantation. Systematic variation of the substituents at positions 2, 4 and 6 of the pyrimidine scaffold led to the discovery of 2-benzylthio-5-cyano-6-(4-methoxyphenyl)-4-morpholinopyrimidine with an IC(50) value of 1.6 μM in the MLR assay.

Immunosuppressive effects of an ethyl acetate extract from Urtica dentata Hand on skin allograft rejection

AIM OF THE STUDY

To investigate the immunosuppressive effects of HPLC qualitied ethyl acetate extract (EAE) from Urtica dentate Hand on skin allograft rejection in a murine model.

MATERIALS AND METHODS

Allo-skin transplantation model was established by placing skin allograft of C57BL/6 mice in the wound bed which was on the back of Balb/c mice. We used FACS to study the effects of EAE on dendritic cells (DCs) maturation and CD4(+)CD25(+)T regulatory cells (Tregs) differentiation. We also studied spleen lymphocyte proliferation and T-bet gene expression in DCs. Concentration of Th1/Th2 cytokines was monitored as markers of Th1/Th2 responses by ELISA.

RESULTS

A significant prolongation of skin allografts survival was observed as a dose-dependent manner in the animals treated with EAE. By FACS, we found that treatment with EAE (200 mg kg(-1)) resulted in an immature statement of DCs and stimulated the differentiation of CD4(+)CD25(+)Tregs. Additionally, the expression of T-bet gene and the proliferation of spleen lymphocytes were efficiently abated in EAE treated mice. Comparing to the model control, EAE-treated recipients showed a significant down-regulation (P<0.01) of Th1 cytokines (IL-2, IFN-gamma) and an obviously increase (P<0.01) of Th2 cytokine (IL-10) in the serum, which presented in a dose-related way.

CONCLUSIONS

The anti-allograft rejection effect of EAE by enhancing CD4(+)CD25(+)Tregs differentiation and sustaining DCs immaturation makes EAE to be a possible choice for treating autoimmune diseases in a way of inducing a stable immunological tolerance state.

Effect of immunosuppressants on T-cell subsets observed in vivo using carboxy-fluorescein diacetate succinimidyl ester labeling

BACKGROUND

The in vivo effects of immunosuppressants on T cells are classically determined using animal models of organ transplantation. These methods are technically difficult and time consuming. A simple in vivo method is needed for screening new immunosuppressants.

METHODS

Donor mouse spleen cells were labeled with a fluorescent dye, carboxy-fluorescein diacetate succinimidyl ester (CFSE), and then injected into the blood of recipient severe combined immunodeficiency mice. Three days after the injection, spleen cells of the recipient mice were isolated and the proliferating alloreactive T cells were analyzed by flow cytometry.

RESULTS

In control recipient mice, 50% of the T cells were proliferating, consisting of both CD4+ and CD8+ T cells. In cyclosporine- or FK506-treated mice, T-cell proliferation was suppressed in the CD4 subset but not in the CD8 subset. On the contrary, T-cell proliferation was significantly reduced in the CD8 subset but not in the CD4 subset in recipient mice treated with rapamycin.

CONCLUSION

The present mouse model using carboxy-fluorescein diacetate succinimidyl ester labeling is simple and fast. It is useful for screening new immunosuppressants and for examining the effect on T-cell subsets.

Whole blood assay for assessment of the mixed lymphocyte reaction

When lymphocytes from genetically different individuals are mixed together in tissue culture blast transformation occurs, a reaction known as the mixed lymphocyte reaction (MLR). The MLR is a clinically relevant in vitro assay where lymphocytes from one individual (effector, E) are incubated with the lymphocytes of another individual (stimulator, S) which have been previously rendered incapable of blast transformation by gamma-irradiation. We have standardised a whole blood (WB) MLR assay where the E lymphocytes were provided by 20 microl of WB and the S lymphocytes were provided by irradiated peripheral blood mononuclear cells (PBMCs) either as a mixed pool of 20 donor PBMCs or as single donor PBMC. The optimum number of S lymphocytes needed was comparatively higher than in the standard PBMC MLR: the optimum calculated E:S ratio was 1:20 compared to a E:S ratio of 1:1 or 3:2 in the standard PBMC MLR. In ten normal individuals the WB/PBMC MLR was similar to the standard PBMC/PBMC MLR. As a clinical example, the WB/PBMC MLR proliferative capacity of 13 patients with malignant mesothelioma was no different from the proliferative capacity of their age-sex matched controls. This standardised WB/PBMC MLR assay is a simple and more practical assay than the standard MLR assay and can be incorporated easily in clinical studies with biological end-points.