腺病毒介导CTLA4Ig及CTLA4双基因在骨髓间充质干细胞中的表达

Expression of adenovirus-mediated CTLA4Ig-IRES-CTLA4 gene in bone marrow mesenchymal stem cells

目的制备CTLA4Ig及CTLA4双基因共表达腺病毒载体,检测重组腺病毒在骨髓间充质干细胞(BMMSCs)中的表达。方法构建大鼠CTLA4Ig融合基因,将CTLA4Ig及CTLA4基因经IRES2连接,通过同源重组获得重组腺病毒表达载体,并在293细胞中进行病毒包装和扩增。检测CTLA4Ig和CTLA4在BMMSCs中的共表达情况及其免疫抑制功能。结果通过同源重组获得携带CTLA4Ig-IRES2-CTLA4的重组腺病毒表达载体,PacⅠ酶切鉴定正确,与脂质体共转染293细胞获得重组腺病毒。用重组腺病毒感染的BMMSCs可同时表达CTLA4Ig及CTLA4,且此类细胞具有明显抑制淋巴细胞反应的功能。结论重组腺病毒感染的BMMSCs可同时表达分泌型CTLA4Ig和膜结合型CTLA4,通过阻断协同刺激通路方式进一步增强BMMSCs的免疫抑制功能。

Objective To construct adenovirus vector harboring CTLA4Ig-IRES-CTLA4 gene, and to express the gene in bone marrow mesenchymal stem cells （BMMSCs）. Methods The cDNA fragments of CTLA4, and the extracellular domains of CTLA4 and IgGFc were cloned to pT-Easy vectors by RT-PCR from the activated splenocytes of Wistar rats. Recombinant adenovirus vector harboring CTLA4Ig-IRES-CTLA4 was produced from AdeasyTM Adenoviral Vector System by homologous recombination between the Adtrack vector （pAdtrack-GFP-CTLA4Ig-IRES-CTLA4） and the plasmid pAdEasy-1 containing most of the human adenovirus serotype 5 （Ad5） genome in E. coli BJ5183 strain, and then packaged and propagated in 293 cells. BMMSCs were infected with the recombinant adenovirus, and the co-expression of both CTLA4Ig and CTLA4 was then detected by RT-PCR and Western blotting. The immunosuppression function of the transfected BMMSCs was investigated by mixed lymphocyte response （MLR）. Results Fusion gene CTLA4Ig was constructed successfully, and the recombinant CTLA4Ig-IRES-CTLA4 adenovirus was then generated by homologous recombination and packaged in 293 cells. The transduction efficiency of recombinant adenovirus in BMMSCs was elevated up to 98.67% determined by flow cytometry using a GFP as marker. CTLA4Ig and CTLA4 were expressed at the same time in BMMSCs detected by RT-PCR and Western blot, and the transfected stem cells showed stronger immunosuppression function than that of BMMSCs or BMMSCs transduced by Ad-CTLA4Ig. Conclusion The BMMSCs transfected by the recombinant adenovirus can co-express CTLA4Ig and CTLA4, which improved the immunosuppression function of BMMSCs in the way of costimulatory pathway blockade.