Takehara M, Murakami M, Inobe M, Tanaka K, Chikuma S, Saito I, Kanegae Y, Yasunami Y, Nakano M, Yamashita K, Todo S, Uede T
Division of Molecular Immunology, Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan.
Hum Gene Ther. 2001 Mar 1;12(4):415-26. doi: 10.1089/10430340150504037.
CTLA4IgG was shown to inhibit the costimulatory signal for T cell activation by interfering with the ligation of CD28 and B7-1 or B7-2. To inhibit various immune responses including acute cellular rejection of allografts, a certain level of serum CTLA4IgG should be maintained for an appropriate period. We previously reported on an adenovirus vector containing CTLA4IgG, which we designated Adex1CACTLA4IgG. Adex1CACTLA4IgG was able to maintain a significant level of serum CTLA4IgG for a long period on intravenous injection, which in turn inhibited various immune responses including protective immunity against infectious agents. To overcome the inhibitory effect, we constructed a new adenovirus vector, Adex1CALoxCTLA4IgGLox, by cloning CTLA4IgG cDNA between two loxP sequences under the control of the CAG promoter. We demonstrated that the administration of adenovirus vector containing Cre recombinase gene (Adex1CACre) at the desired time induced Cre-mediated recombination within a gene derived from Adex1CALoxCTLA4IgGLox vector, and the cDNA of CTLA4IgG was excised from the transduced gene and terminated the expression of CTLA4IgG in vitro and in vivo. More importantly, we also demonstrated that the long-term acceptance of allografts was achieved after the termination of CTLA4IgG expression, while the immune response against adenovirus was restored.
CTLA4IgG已被证明可通过干扰CD28与B7-1或B7-2的连接来抑制T细胞活化的共刺激信号。为抑制包括同种异体移植物急性细胞排斥反应在内的各种免疫反应，应在适当的时间段内维持一定水平的血清CTLA4IgG。我们之前报道了一种含有CTLA4IgG的腺病毒载体，我们将其命名为Adex1CACTLA4IgG。静脉注射后，Adex1CACTLA4IgG能够长时间维持血清CTLA4IgG的显著水平，进而抑制包括针对感染因子的保护性免疫在内的各种免疫反应。为克服这种抑制作用，我们构建了一种新的腺病毒载体Adex1CALoxCTLA4IgGLox，方法是在CAG启动子的控制下，将CTLA4IgG cDNA克隆到两个loxP序列之间。我们证明，在所需时间给予含有Cre重组酶基因的腺病毒载体（Adex1CACre）可诱导Adex1CALoxCTLA4IgGLox载体衍生基因内的Cre介导重组，CTLA4IgG的cDNA从转导基因中切除，从而在体外和体内终止CTLA4IgG的表达。更重要的是，我们还证明，在CTLA4IgG表达终止后实现了同种异体移植物的长期存活，同时恢复了对腺病毒的免疫反应。
