earticle

영어

Xenotransplantation has been getting attention as an attractive strategy to overcome lack of organ-donors in clinical transplantation. However, xenotransplantation show more severe immune responses than organ transplants of the same species. In particular, the hyper acute rejection is caused by the alpha(1,3) galactosyl-transferase expressed on the porcine organ cell membrane and the organ dies within a few minutes. Recently, alpha(1,3)galactosyl-transferase knockout pigs to reduce the problem of hyper acute rejection. However, when the organs survive in the body for a long time, cell- mediated immune rejection occurs due to intrinsic immune response and adaptive immune response, which are left as obstacles for successful xenograft. This immune response is mainly interacted with the MHC class I molecule and various receptors of the immune cell. The US11 gene and the US2 gene are hCMV(human cytomegalovirus)-derived genes that retro-translocate MHC Class I molecules in the endoplasmic reticulum to inhibit expression on the surface of cell membrane, resulting in an immune evasion response. Our study focused on introducing the US11 and US2 genes into the pig fibroblast to evaluate gene function and reduce cell mediated rejection through two genes. The fetal fibroblast was obtained from Korean native pig, and the US2 and US11 genes were inserted into the cells by constructing pCAGGS/US11, pcDNA3.1/ US2 and pcDNA3.1/US2-2A-US11 vectors. G418 (500 ng/mL) and Blasticidin (20 ng/ mL) were treated for 14 days, and gene expression was confirmed by RT-PCR. The MHC Class I expression was confirmed by FACS using SLA-I antibody. NK cells and CD8+T cells were co-cultured with transgene cells and MTT assay was used to confirm results of cytotoxicity. In the US2 and US11 transfected cell lines, MHC class I expression was found to be higher than Wildtype in FACS results, it’s suggested that the expression of this gene was increased as part of the cell defense mechanism due to the insertion of the virus gene. In addition, there were no significant differences in cytotoxicity of NK cell of US11 and US2, it’s presumed that NK cell mainly respond to degranulation of perforin and granzyme or binding of NKG2A, NKG2D receptor than MHC Class I immune response. On the other hand, cytotoxicity of CD8+ T cells was shown lower cell lysis than the control group. Further studies will conduct that the confirm to performance of co-expression of US2 and US11 on immune reject and will apply a novel strategy to attenuate the activity of NK cells.