Constitutive expression of murine CTLA4Ig from a recombinant adenovirus vector results in prolonged transgene expression

Preventive effect of pcDNA3-CTLA4Ig plasmid transfection on islet allograft rejection in mice

AIM: To study the effect of pcDNA3-CTLA4Ig plasmid on islet allograft rejection in mice.

METHODS: C57BL/6 mice were randomly divided into control group, blank group and experiment group (transfected with pcDNA3-CTLA4Ig plasmid). The level of serum CTLA4Ig was detected by Western blot on day 5 after transfection. Blood glucose was examined after operation every other day. Immunohistochemical staining was used to determine the expression of insulin. ³H-thymidine incorporation was performed to detect the ability of T lymphocyte increment and the levels of CD4⁺ and CD8⁺ T lymphocytes were detected by flow cytometry on day 7 after transplantation.

RESULTS: Five days after transfection, Western blot demonstrated serum expression of CTLA4Ig, and the transfection efficacy was 27.50%. Blood glucose maintained at the normal level for a longer period of time in the experiment group, and on day 7, the proliferation of lymphocytes was markedly decreased (P < 0.05). The levels of CD4⁺ and CD8⁺ T lymphocytes were significantly lower in the experiment group than those in the control and blank group (CD4⁺: 14.38% ± 0.84% vs 20.56% ± 0.68%, 21.04% ± 1.14%, P < 0.05; CD8⁺: 14.77% ± 0.92% vs 24.63% ± 1.30%, 23.84% ± 1.21%, P < 0.05), and the intensity of immunohistochemical staining was also stronger.

CONCLUSION: CTLA4 gene can be transferred into mouse muscular cells by cation liposome and express its products in the serum, which leads to the inhibition of islet allograft rejection by the blockage of B7/CD28 signal pathway.