重组腺相关病毒载体诱导的天然免疫反应及机制

重组腺相关病毒(rAAV)已成为基因治疗领域应用最广泛的载体之一。临床前研究显示其具有很高的安全性,但人体免疫毒性仍是制约其临床疗效的关键,因此有关rAAV免疫机制的研究成为近期热点。尽管天然免疫在获得性免疫反应中发挥重要作用,但与rAAV有关的天然免疫研究过去一直未被重视。直到最近,才确认有至少3种人体细胞(树突状细胞、巨噬细胞和内皮细胞)参与了rAAV的天然免疫,作用机制为可识别载体基因组的TLR9或病毒衣壳TLR2所介导,NF-κB或干扰素调节因子(IRFs)信号通路被激活,导致各种炎性因子及I型干扰素的大量表达。自身互补型rAAV诱导的TLR9依赖性天然免疫较单链rAAV更为强烈。本文重点对近期发现的激活天然免疫反应的宿主与rAAV的相互作用、涉及的信号通路、天然免疫对获得性免疫以及转基因表达的影响进行综述。

Innate immune mechanisms against recombinant adeno-associated virus vectors--a review

Recombinant adeno-associated virus (rAAV) is one of the most commonly used vectors for gene therapy. Despite the promising safety profile demonstrated in preclinical trials, the clinic efficacy of using rAAV was hampered by undesired response from the immune system. It is important to understand the mechanisms that lead to the induction of immune response against rAAV. Although a crucial role for innate immunity is shaping adaptive immune responses, the innate immune to rAAV was ignored in the past. Till now, at least three human cell types (dendritic cells, macrophages and endothelial cells) were discovered to be involved in sensing rAAV infection. The engagement of TLR9 by rAAV vector genomes triggers the activation of NF-kappaB signaling cascades, leading to the induction of pro-inflammatory cytokine genes. The viral capsid components are detected by TLR2, and this leads to the production of type I interferon mediated by interferon regulatory factors (IRFs) pathway. Self-complementary rAAV vectors induced higher TLR9 dependent innate immune response than single stranded rAAV. This review highlights the recent findings regarding the innate immune responses to rAAV vectors, the signaling pathways involved, and the impacts of innate immunity on the adaptive immune response to rAAV and its transgene expression.