Research and Development, uniQure BV, Amsterdam, The Netherlands.
J Gene Med. 2013 Jun-Jul;15(6-7):219-32. doi: 10.1002/jgm.2712.
Muscle represents an important tissue target for adeno-associated virus (AAV) vector-mediated gene transfer in muscular, metabolic or blood-related genetic disorders. However, several studies have demonstrated the appearance of immune responses against the transgene product after intramuscular AAV vector delivery that resulted in a limited efficacy of the treatment. Use of microRNAs that are specifically expressed in antigen-presenting cells (APCs) is a promising approach for avoiding those immune responses. Cellular mir-142-3p, which is APC-specific, is able to repress the translation of its target cellular transcripts by binding to a specific target sequences.
In the present study, we explored the potential of mir-142-3p specific target sequences with respect to reducing or abolishing immune responses directed against ovalbumin (OVA), a highly immunogenic protein, expressed as transgene and delivered by AAV1 vector administered intramuscularly.
The occurrence of immune responses against OVA transgene following intramuscular delivery by AAV have been described previously and resulted in the loss of OVA protein expression. In the present study, we demonstrate that OVA protein expression was maintained when mir-142-3pT sequences were incorporated into the expression cassette. The sustained expression of OVA protein over time correlated with a reduced increase in anti-OVA antibody levels. Furthermore, no cellular infiltrates were observed in the muscle tissue when AAV1 vectors containing four or eight repeats of mir-142-3p target sequences after the OVA sequence were used.
The rising humoral and cellular immune responses against OVA protein after intramuscular delivery can be efficiently reduced by the use of mir-142-3p target sequences.
腺相关病毒（AAV）载体介导的基因转移在肌肉、代谢或血液相关遗传疾病中，肌肉是重要的组织靶标。然而，有几项研究表明，在肌肉内 AAV 载体递送后，会出现针对转基因产物的免疫反应，从而导致治疗效果有限。使用在抗原呈递细胞（APC）中特异性表达的 microRNAs 是避免这些免疫反应的一种有前途的方法。细胞 mir-142-3p 是 APC 特异性的，能够通过与特定的靶序列结合来抑制其靶细胞转录物的翻译。
在本研究中，我们探讨了 mir-142-3p 特异性靶序列在减少或消除针对卵清蛋白（OVA）的免疫反应方面的潜力，OVA 是一种高度免疫原性的蛋白质，作为转基因通过 AAV1 载体肌肉内给药表达。
先前已经描述了 AAV 肌肉内递送后针对 OVA 转基因的免疫反应的发生，导致 OVA 蛋白表达的丧失。在本研究中，我们证明了当 mir-142-3pT 序列被整合到表达盒中时，OVA 蛋白表达得以维持。OVA 蛋白表达随时间的持续与抗 OVA 抗体水平的升高呈负相关。此外，当 AAV1 载体包含 OVA 序列后的四个或八个重复的 mir-142-3p 靶序列时，肌肉组织中未观察到细胞浸润。
通过使用 mir-142-3p 靶序列，可以有效地减少肌肉内递送后针对 OVA 蛋白的体液和细胞免疫反应。
