Li Chengwen, Hirsch Matthew, Asokan Aravind, Zeithaml Brian, Ma Hong, Kafri Tal, Samulski R Jude
Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
J Virol. 2007 Jul;81(14):7540-7. doi: 10.1128/JVI.00529-07. Epub 2007 May 2.
A recent clinical trial has suggested that recombinant adeno-associated virus (rAAV) vector transduction in humans induces a cytotoxic T-lymphocyte (CTL) response against the AAV2 capsid. To directly address the ability of AAV capsid-specific CTLs to eliminate rAAV-transduced cells in vitro and in vivo in mice, we first demonstrated that AAV2 capsid-specific CTLs could be induced by dendritic cells with endogenous AAV2 capsid expression or pulsed with AAV2 vectors. These CTLs were able to kill a cell line stable for capsid expression in vitro and also in a mouse tumor xenograft model in vivo. Parent colon carcinoma (CT26) cells transduced with a large amount of AAV2 vectors in vitro were also destroyed by these CTLs. To determine the effect of CTLs on the elimination of target cells transduced by AAV2 vectors in vivo, we carried out adoptive transfer experiments. CTLs eliminated liver cells with endogenous AAV2 capsid expression but not liver cells transduced by AAV2 vectors, regardless of the reporter genes. Similar results were obtained for rAAV2 transduction in muscle. Our data strongly suggest that AAV vector-transduced cells are rarely eliminated by AAV2 capsid-specific CTLs in vivo, even though the AAV capsid can induce a CTL response. In conclusion, AAV capsid-specific CTLs do not appear to play a role in elimination of rAAV-transduced cells in a mouse model. In addition, our data suggest that the mouse model may not mimic the immune response noted in humans and additional modification to AAV vectors may be required for further study in order to elicit a similar cellular immune response.
最近的一项临床试验表明，重组腺相关病毒（rAAV）载体转导在人体中会诱导针对AAV2衣壳的细胞毒性T淋巴细胞（CTL）反应。为了直接研究AAV衣壳特异性CTL在体外和小鼠体内消除rAAV转导细胞的能力，我们首先证明，具有内源性AAV2衣壳表达的树突状细胞或用AAV2载体脉冲处理的树突状细胞能够诱导产生AAV2衣壳特异性CTL。这些CTL能够在体外杀死稳定表达衣壳的细胞系，在体内的小鼠肿瘤异种移植模型中也能发挥作用。体外大量转导AAV2载体的亲代结肠癌细胞（CT26）也会被这些CTL破坏。为了确定CTL对体内AAV2载体转导的靶细胞消除作用的影响，我们进行了过继转移实验。CTL能够消除具有内源性AAV2衣壳表达的肝细胞，但不能消除由AAV2载体转导的肝细胞，无论报告基因如何。在肌肉中进行rAAV2转导也得到了类似的结果。我们的数据有力地表明，尽管AAV衣壳能够诱导CTL反应，但在体内，AAV载体转导的细胞很少被AAV2衣壳特异性CTL消除。总之，在小鼠模型中，AAV衣壳特异性CTL似乎在消除rAAV转导细胞方面不起作用。此外，我们的数据表明，小鼠模型可能无法模拟人类中观察到的免疫反应，为了引发类似的细胞免疫反应，可能需要对AAV载体进行进一步研究的额外修饰。
