Department of Medicine, University of California, San Francisco, CA, USA.
Gene Ther. 2013 Oct;20(10):987-96. doi: 10.1038/gt.2013.22. Epub 2013 Jun 13.
Neonatal AAV8-mediated Factor IX (F.IX) gene delivery was applied as a model for exploring mechanisms of tolerance induction during immune ontogeny. Intraperitoneal delivery of AAV8/ Factor IX (hF.IX) during weeks 1-4 of life, over a 20-fold dose range, directed stable hF.IX expression, correction of coagulopathy in F.IX-null hemophilia B mice, and induction of tolerance to hF.IX; however, only primary injection at 1-2 days of life enabled increasing AAV8-mediated hF.IX expression after re-administration, due to the absence of anti-viral capsid antibodies. Adoptive splenocyte transfer from tolerized mice demonstrated induction of CD4(+)CD25(+) T regulatory (T(reg)) populations that specifically suppressed anti-hF.IX antibody responses, but not responses to third party antigen. Induction of hF.IX antibodies was only observed in tolerized mice after in vivo CD4(+)CD25(+) cell depletion and hF.IX challenge. Thus, primary injection of AAV during a critical period in the first week of life does not elicit antiviral responses, enabling re-administration of AAV and augmentation of hF.IX levels. Expansion of hF.IX-specific CD4(+)CD25(+) T(regs) has a major role in tolerance induction early in immune ontogeny. Neonatal gene transfer provides a useful approach for defining the ontogeny of immune responses and may suggest approaches for inducing tolerance in the context of genetic therapies.
新生儿 AAV8 介导的因子 IX（F.IX）基因传递被用作探索免疫发生过程中诱导耐受机制的模型。在生命的第 1-4 周内通过腹腔内给予 AAV8/因子 IX（hF.IX），在 20 倍剂量范围内，可实现稳定的 hF.IX 表达、纠正 F.IX 缺失的血友病 B 小鼠的凝血功能障碍，并诱导对 hF.IX 的耐受；然而，只有在生命的第 1-2 天进行初次注射，才能在重新给药后增加 AAV8 介导的 hF.IX 表达，这是由于缺乏抗病毒衣壳抗体。来自耐受小鼠的过继性脾细胞转移证明了诱导 CD4(+)CD25(+)T 调节（T(reg)）细胞群体的能力，这些细胞群体特异性抑制抗 hF.IX 抗体反应，但不抑制对第三方抗原的反应。仅在耐受小鼠中观察到 hF.IX 抗体的诱导，这是在体内 CD4(+)CD25(+)细胞耗竭和 hF.IX 挑战后观察到的。因此，在生命的第一周的关键时期内对 AAV 进行初次注射不会引起抗病毒反应，从而能够再次给予 AAV 并增加 hF.IX 水平。hF.IX 特异性 CD4(+)CD25(+)T(reg)的扩增在免疫发生早期的耐受诱导中具有重要作用。新生儿基因转移为定义免疫反应的个体发生提供了一种有用的方法，并且可能提示在基因治疗背景下诱导耐受的方法。
