HIV-1通过调控miR-146a逃逸巨噬细胞抗病毒天然免疫的分子机制

It remains unclear about how Human Immunodeficiency Virus (HIV) escapes from eradication by human innate immunity and establishes persistent infection. It becomes a big challenge that anti-viral treatment fail to clean HIV-1 in low-replicating state. We found in our previous study that, miR-146a was significantly up-regulated while cytokines such as interferon and TNF-alpha were induced in early infection phase but reduced during later phase in human primary macrophage. There are several transcription factor NFkB binding sites in the promoter of miR-146a gene, and the induced expression of miR-146a by LPS, IL-1 band TNF-alpha is NFkB dependent. Therefore, we hypothesize that HIV-1 infection up-regulates miR-146a, the induced miR-146a then down-regulates interferon and TNF-alpha or other antiviral cytokines, and this negative feedback regulation loop helps the virus establishing a persistent or latent infection. We plan to utilize HIV-1 infected human primary macrophage model, to study: (1) how HIV-1 infection up-regulates miR-146a expression in macrophage? (2) effect of miR-146a on HIV-1 infection and replication; (3) targets of miR-146a, especially those target genes of antiviral cytokines and effects of miR-146a on macrophage function. This study aims to discover mechanism of miR-146a contributes to HIV-1 persistent infection, and to give evidence of miR-146a, as a negative regulator, helping HIV-1 to escape from innate immunity. Our study may offer new strategy on HIV-1 latent infection treatment.

艾滋病治疗手段HAART对低水平复制的HIV-1病毒没有效果，成为目前治疗方法的盲区。HIV-1逃逸天然免疫清除、建立慢性感染的机制尚不完全清楚。我们的前期研究发现，在人原代巨噬细胞内miR-146a表达逐步升高，与HIV-1病毒复制水平呈正相关，而与干扰素、TNF-alpha等细胞因子的分泌呈负相关，提示miR-146a可能参与弱化抗HIV-1病毒的天然免疫和炎症反应。我们拟以HIV-1感染的巨噬细胞为模型：研究HIV-1上调miR-146a表达的分子机制；筛查被HIV-1下调的抗病毒因子；确定miR-146a的作用靶点，系统研究miR-146a对巨噬细胞相关抗病毒天然免疫的抑制效应。本项目提出HIV病毒通过调控miR-146a逃逸巨噬细胞抗病毒天然免疫、建立慢性感染新机制，并探索以miR-146a为靶点抑制病毒复制的可能性，为干预艾滋病毒潜伏期治疗提供新思路。

HIV-1病毒持续性感染能诱导miR-146a的表达，miR-146a作为免疫系统负调控分子，通过靶向多个免疫系统关键分子，负调控免疫系统。而对于HIV-1感染来说，这种负调控则会被病毒利用，有利于病毒与宿主长期共存，并逐渐累积致病效应。首先，我们通过分子生物学手段，鉴定了一个新的miR-146a作用靶点CCL5/RANTES，CCL5是一个重要的趋化因子，在健康者体内，可有效趋化多种免疫细胞向感染部位或炎症部位靠近并发挥作用。HIV-1感染诱导的持续性表达miR-146a，显著压制了通过CCL5介导的趋化效应，有利于病原体逃逸机体的免疫清除作用。.同时我们利用CRISPR/Cas9技术敲除miR-146a，以探索在敲除miR-146a后，能否在一定程度上回复细胞因子，T细胞耗竭分子表达，从而增强免疫反应，抑制病毒复制。