Leishmania donovani inhibits macrophage apoptosis and pro-inflammatory response through AKT-mediated regulation of β-catenin and FOXO-1
Leishmania donovani inhibits macrophage apoptosis and pro-inflammatory response through AKT-mediated regulation of β-catenin and FOXO-1
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DOI：
10.1038/cdd.2016.101
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发表时间：
2016-11-01
影响因子：
12.4
通讯作者：
Ukil, Anindita
中科院分区：
文献类型：
--
作者：
Gupta, Purnima;Srivastav, Supriya;Ukil, Anindita
为了建立感染，巨噬细胞内寄生虫杜氏利什曼原虫需要抑制宿主防御参数，如炎症细胞因子的产生和细胞凋亡。在本研究中，我们证明了寄生虫通过利用单个宿主调节因子AKT来调节其下游转录因子β-连环蛋白和FOXO-1来实现这两个目标。L.用AKT抑制剂或显性负性AKT构建体处理的杜诺凡尼感染的RAW 264.7和骨髓衍生的巨噬细胞（BMDM）显示出抗炎细胞因子产生减少和宿主细胞凋亡增加，导致寄生虫存活减少。抑制诱导的活化AKT触发磷酸化介导的其下游靶标GSK-3 β的失活。失活的GSK-3 β，反过来，可以不再螯合胞质β-连环蛋白，抗凋亡转录调节因子，从它的核易位在感染过程中证明。组成型活性GSK-3 β转染L. donovani感染的细胞模拟AKT抑制的作用，siRNA介导的β-连环蛋白沉默导致线粒体电位的破坏，沿着增加的半胱天冬酶-3活性和IL-12产生，导致寄生虫存活减少。除了激活抗凋亡β-连环蛋白，磷酸化AKT抑制FOXO-1的激活，FOXO-1是一种促凋亡转录调节因子。当感染的细胞用显性阴性AKT构建体转染时，在感染期间被抑制的FOXO-1的核保留被逆转。在感染的巨噬细胞中FOXO-1的过表达不仅记录了细胞凋亡的增加，而且促进了TLR 4表达和NF-κ B活性的增强沿着IL-1 β的增加和IL-10分泌的减少。体内施用AKT抑制剂显著降低了肝脏和脾脏寄生虫负荷，并将细胞因子平衡切换为有利于宿主。相比之下，GSK-3 β抑制剂未导致感染性参数的任何显著变化。总体上，我们的研究结果表明，L。donovani触发AKT活化以调节GSK-3 β/β-连环蛋白/FOXO-1轴，从而确保抑制宿主细胞凋亡和其巨噬细胞内存活所必需的免疫应答。
In order to establish infection, intra-macrophage parasite Leishmania donovani needs to inhibit host defense parameters like inflammatory cytokine production and apoptosis. In the present study, we demonstrate that the parasite achieves both by exploiting a single host regulator AKT for modulating its downstream transcription factors, beta-catenin and FOXO-1. L. donovani-infected RAW264.7 and bone marrow-derived macrophages (BMDM) treated with AKT inhibitor or dominant negative AKT constructs showed decreased anti-inflammatory cytokine production and increased host cell apoptosis resulting in reduced parasite survival. Infection-induced activated AKT triggered phosphorylation-mediated deactivation of its downstream target, GSK-3 beta. Inactivated GSK-3 beta, in turn, could no longer sequester cytosolic beta-catenin, an anti-apoptotic transcriptional regulator, as evidenced from its nuclear translocation during infection. Constitutively active GSK-3 beta-transfected L. donovani-infected cells mimicked the effects of AKT inhibition and siRNA-mediated silencing of beta-catenin led to disruption of mitochondrial potential along with increased caspase-3 activity and IL-12 production leading to decreased parasite survival. In addition to activating antiapoptotic beta-catenin, phospho-AKT inhibits activation of FOXO-1, a pro-apoptotic transcriptional regulator. Nuclear retention of FOXO-1, inhibited during infection, was reversed when infected cells were transfected with dominant negative AKT constructs. Overexpression of FOXO-1 in infected macrophages not only documented increased apoptosis but promoted enhanced TLR4 expression and NF-kappa B activity along with an increase in IL-1 beta and decrease in IL-10 secretion. In vivo administration of AKT inhibitor significantly decreased liver and spleen parasite burden and switched cytokine balance in favor of host. In contrast, GSK-3 beta inhibitor did not result in any significant change in infectivity parameters. Collectively our findings revealed that L. donovani triggered AKT activation to regulate GSK-3 beta/beta-catenin/FOXO-1 axis, thus ensuring inhibition of both host cell apoptosis and immune response essential for its intra-macrophage survival.