Objective: To study the effect of Tripterygium hypoglaucum (level) Hutch (THH) extraction in alleviating the graft-versus-host disease (GVHD) in mice after allogeneic bone marrow transplantation and to explore its mechanism.
Methods: Mixture of 2 x 10(7) bone marrow cells and 2 x 10(7) spleen cells obtained from C57BL/6 mouse were transplanted into the myelo-ablative irradiated inbred BALB/c mouse (H-2(d)). The experimental mice were designed into 4 groups: the control group (A), the Cyclosporine A (CsA) group (B), the THH group (C), and the CsA + THH group (D). Condition of GVHD and transplanted chimera were observed, percentage of CD4(+)CD25(+) T cell in peripheral blood were detected by flow cytometry, and the expression of Foxp3 mRNA in splenocyte at different time points were determined by real-time FQ-PCR.
Results: CD4(+)CD25(+) T cell in Group B, C and D increased from the 10th day, peaked on the 15th day, descended after then, but the level in Group D maintained higher than that in the other three groups (P<0.05). Expression of Foxp3 mRNA in recipients' splenocytes increased gradually, reached peak on the 15th day and followed with gradual decreasing, the highest peak and the slowest decreasing was shown in Group D, so the level was still rather higher in Group D on the 30th day. The survival time in the three treated group (B, C and D) were all longer than that in the control group A (P<0.05). GVHD signs and pathologic changes in the three treated groups were milder than in the control group. Allogeneic chimerism rates (H-2(d)) in all groups were over 95%.
Conclusion: THH could prevent GVHD in mice after allogeneic bone marrow transplantation, and prolong their survival time, the mechanism is possibly related with its immunosuppressive effect in raising CD4(+)CD25(+) T cells and promoting the Foxp3 mRNA expression. THH combining with small dose CsA shows synergic effect in preventing GVHD.