Development of the gene therapy model for allergic diseases

Bcl6-KO小鼠无生发中心形成，变态反应性炎症严重，嗜酸性粒细胞浸润。我们发现BCL6在T细胞中的靶基因之一是IL-5基因。本课题研究了BCL6在记忆B细胞发育中的功能作用，并试图通过建立BCL6基因表达受控的动物模型来建立过敏性疾病的基因治疗模型。我们发现(1)BCL6-KO小鼠产生了正常水平的二次IgG1抗体，并在脾中产生了可转移的IgG1记忆B细胞。在这些记忆B细胞中，V-hedvy基因突变为零。我们已经建立了携带Ig-BCL6的转基因小鼠，并在转基因小鼠中增强了生发中心的形成和记忆反应。因此，Bcl6在生发中心的体细胞超突变和记忆B细胞的产生中是必不可少的。(2)建立了携带lck-bcl6基因的转基因小鼠。当抗CD3抗体刺激LCK-BCL6小鼠脾T细胞时，IL-5的产生被特异性地抑制。这些LCK-BCL6小鼠与BCL6-KO小鼠交配，BCL6-KO小鼠的变态反应性炎症得到完全控制。我们建立了利用病毒载体进行基因转移的方法。我们希望在不久的将来开发出治疗过敏性疾病的有效的基因治疗方法。

BCL6-KO mice display no germinal center formation and severe allergic inflammation with eosinophilic infiltration. We found that one of the target gene of BCL6 in T cells is the IL-5 gene. In this project, we investigated the functional role of BCL6 in memory B cell development and tried to develop the gene therapy model for allergic diseases by establishing model animals in which expression of BCL6 is controlled. We show that (1) BCL6-KO mice produced control levels of secondary IgG1 antibodies, and generated transferable IgG1 memory B cells in the spleen. Mutation in the V-hedvy gene was nil in those memory B cells. We have established transgenic mice carrying the Ig-BCL6, and the germinal center formation and memory responses were augmented in transgenic mice. Therefore, Bcl6 is essential for somatic hypermutation and generation of memory B cells in germinal centers. (2) We have established transgenic mice carrying the lck-BCL6 gene. When splenic T cells from lck-BCL6 mice were stimulated with anti-CD3 antibody, IL-5 production was specifically suppressed. Those lck-BCL6 mice were mated with BCL6-KO mice and the allergic inflammation in BCL6-KO mice was completely controlled. We have established the gene transfer method using virus vectors. We wish to develop the efficient gene therapy method for allergic diseases near future.