The Immunomodulating Effects of Thalidomide and Dexamethasone in a Murine Cardiac Allograft Transplantation Model

Purpose: The immunomodulatory effects of thalidomide (TM) and dexamethasone (DX) on immune cells and their co-stimulatory, co-inhibitory molecules in vitro and in vivo have been previously reported. The current study investigated the effects of TM and the combinatorial treatment with DX on immune cells using a murine cardiac allograft transplantation model. Materials and Methods: Intraabdominal transplant of cardiac allografts from BALB/c (H-2d) donors to C57BL/6 (H-2b) recipients was performed. After transplantation, mice were injected daily with TM or DX or a combination of both TM and DX (TM/DX) by intraperitoneal route until the time of graft loss. CD4+ T cell subsets and CD11c+ cells in the peripheral blood mononuclear cells and spleen were examined and quantified with flow cytometry. Serum IL-6 levels were measured by enzyme-linked immunosorbent assay on day 7. Results: The mean graft survivals were 6.86 days in the untreated group, and 10.0 days in the TM/DX group (p<0.001). The TM/DX treatment affected the CD4+ T cell subsets without suppressing the total CD4+ T cell population. The CD4+FOXP3+/CD4+CD44hi T cell ratio increased. Increase in cell counts and median fluorescence intensity on CD11c+CD85k+ with TM/DX were observed. The inhibition of pro-inflammatory cytokine interleukin-6 was also observed. Conclusion: These outcomes suggest the immunomodulating effect of the TM/DX combinatorial treatment. In conclusion, TM/ DX combination may be a promising immunomodulatory approach for preventing allograft rejection and improving graft survival by inducing tolerance in transplantation.