Exosomes from HIV-1-infected Cells Stimulate Production of Pro-inflammatory Cytokines through Trans-activating Response (TAR) RNA
Exosomes from HIV-1-infected Cells Stimulate Production of Pro-inflammatory Cytokines through Trans-activating Response (TAR) RNA
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DOI：
10.1074/jbc.m115.662171
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发表时间：
2016-01-15
影响因子：
4.8
通讯作者：
Kashanchi, Fatah
中科院分区：
文献类型：
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作者：
Sampey, Gavin C.;Saifuddin, Mohammed;Kashanchi, Fatah
HIV-1感染导致慢性疾病，因为长期高效抗逆转录病毒治疗可以将病毒滴度降低到无法检测的水平。然而，停止治疗会迅速增加病毒负荷。此外，接受高效抗逆转录病毒治疗的患者经常会出现各种代谢紊乱、神经认知异常和心血管疾病。我们先前已经表明，含有反式激活反应（TAR）元件RNA的外泌体增强了未分化的幼稚细胞对HIV-1感染的易感性。这项研究表明，来自HIV-1感染的原代细胞的外泌体具有高度丰富的TAR RNA，如通过RT-实时PCR检测的。有趣的是，在来自HIV-1感染的人源化小鼠的血清中也检测到高达一百万拷贝的TAR RNA/μ l，这表明TAR RNA在体内可能是稳定的。来自HIV-1感染细胞的外泌体与原代巨噬细胞的孵育导致促炎细胞因子IL-6和TNF-β的急剧增加，表明含有TAR RNA的外泌体可以在控制细胞因子基因表达中发挥直接作用。完整的TAR分子能够有效地结合PKR和TLR 3，而5'和3'茎（TAR microRNA）最好地结合TLR 7和TLR 8，而不结合PKR。TAR与PKR的结合不导致其磷酸化，因此，TAR可能是细胞中的显性负性诱饵分子。TLR通过TAR RNA或TAR microRNA结合可能激活NF-κ B通路并调节细胞因子表达。总的来说，这些结果意味着含有TAR RNA的外泌体可以直接影响促炎细胞因子基因表达，并且可以解释在cART下在HIV-1感染患者中观察到的炎症的可能机制。
HIV-1 infection results in a chronic illness because longterm highly active antiretroviral therapy can lower viral titers to an undetectable level. However, discontinuation of therapy rapidly increases virus burden. Moreover, patients under highly active antiretroviral therapy frequently develop various metabolic disorders, neurocognitive abnormalities, and cardiovascular diseases. We have previously shown that exosomes containing trans-activating response (TAR) element RNA enhance susceptibility of undifferentiated naive cells to HIV-1 infection. This study indicates that exosomes from HIV-1-infected primary cells are highly abundant with TAR RNA as detected by RT-real time PCR. Interestingly, up to a million copies of TAR RNA/ mu l were also detected in the serum from HIV-1-infected humanized mice suggesting that TAR RNA may be stable in vivo. Incubation of exosomes from HIV-1-infected cells with primary macrophages resulted in a dramatic increase of proinflammatory cytokines, IL-6 and TNF-beta, indicating that exosomes containing TAR RNA could play a direct role in control of cytokine gene expression. The intact TAR molecule was able to bind to PKR and TLR3 effectively, whereas the 5' and 3' stems (TAR microRNAs) bound best to TLR7 and -8 and none to PKR. Binding of TAR to PKR did not result in its phosphorylation, and therefore, TAR may be a dominant negative decoy molecule in cells. The TLR binding through either TAR RNA or TAR microRNA potentially can activate the NF-kB pathway and regulate cytokine expression. Collectively, these results imply that exosomes containing TAR RNA could directly affect the proinflammatory cytokine gene expression and may explain a possible mechanism of inflammation observed in HIV-1-infected patients under cART.