Rogers Geoffrey L, Shirley Jamie L, Zolotukhin Irene, Kumar Sandeep R P, Sherman Alexandra, Perrin George Q, Hoffman Brad E, Srivastava Arun, Basner-Tschakarjan Etiena, Wallet Mark A, Terhorst Cox, Biswas Moanaro, Herzog Roland W
Department of Pediatrics, Division of Cellular and Molecular Therapy, University of Florida, Gainesville, FL.
Center of Molecular and Cellular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA.
Blood. 2017 Jun 15;129(24):3184-3195. doi: 10.1182/blood-2016-11-751040. Epub 2017 May 3.
Adeno-associated virus (AAV) is a replication-deficient parvovirus that is extensively used as a gene therapy vector. CD8 T-cell responses against the AAV capsid protein can, however, affect therapeutic efficacy. Little is known about the in vivo mechanism that leads to the crosspriming of CD8 T cells against the input viral capsid antigen. In this study, we report that the Toll-like receptor 9 (TLR9)-MyD88 pattern-recognition receptor pathway is uniquely capable of initiating this response. By contrast, the absence of TLR2, STING, or the addition of TLR4 agonist has no effect. Surprisingly, both conventional dendritic cells (cDCs) and plasmacytoid DCs (pDCs) are required for the crosspriming of capsid-specific CD8 T cells, whereas other antigen-presenting cells are not involved. TLR9 signaling is specifically essential in pDCs but not in cDCs, indicating that sensing of the viral genome by pDCs activates cDCs in trans to cross-present capsid antigen during CD8 T-cell activation. Cross-presentation and crosspriming depend not only on TLR9, but also on interferon type I signaling, and both mechanisms can be inhibited by administering specific molecules to prevent induction of capsid-specific CD8 T cells. Thus, these outcomes directly point to therapeutic interventions and demonstrate that innate immune blockade can eliminate unwanted immune responses in gene therapy.
腺相关病毒（AAV）是一种复制缺陷型细小病毒，被广泛用作基因治疗载体。然而，针对AAV衣壳蛋白的CD8 T细胞反应会影响治疗效果。关于导致CD8 T细胞针对输入病毒衣壳抗原进行交叉呈递的体内机制，人们了解甚少。在本研究中，我们报告Toll样受体9（TLR9）-MyD88模式识别受体途径独特地能够引发这种反应。相比之下，缺乏TLR2、STING或添加TLR4激动剂均无影响。令人惊讶的是，衣壳特异性CD8 T细胞的交叉呈递需要常规树突状细胞（cDC）和浆细胞样树突状细胞（pDC），而其他抗原呈递细胞不参与。TLR9信号传导在pDC中特别重要，但在cDC中并非如此，这表明pDC对病毒基因组的感知通过反式激活cDC，从而在CD8 T细胞激活过程中交叉呈递衣壳抗原。交叉呈递和交叉致敏不仅依赖于TLR9，还依赖于I型干扰素信号传导，并且通过施用特定分子来抑制衣壳特异性CD8 T细胞的诱导，这两种机制均可被抑制。因此，这些结果直接指向治疗干预措施，并表明先天性免疫阻断可以消除基因治疗中不需要的免疫反应。
