Toll-like receptor 4 mediates the antitumor host response induced by a 55-kilodalton protein isolated from Aeginetia indica L., a parasitic plant
Toll-like receptor 4 mediates the antitumor host response induced by a 55-kilodalton protein isolated from Aeginetia indica L., a parasitic plant
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DOI：
10.1128/cdli.11.3.483-495.2004
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发表时间：
2004-05-01
期刊：
影响因子：
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通讯作者：
Ohkubo, S
中科院分区：
文献类型：
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作者：
Okamoto, M;Oh-e, G;Ohkubo, S
从寄生植物印度山羊草种子提取物中分离出一种55 kDa的蛋白AILb-A，它能诱导Th1型T细胞反应，并在荷瘤小鼠中产生显著的抗肿瘤作用。在本研究中，我们研究了Toll样受体(TLRs)在AILb-A诱导的免疫反应中的作用，TLRs参与了病原体诱导的细胞信号转导。在使用依赖于核因子kappaB的报告质粒进行荧光素酶活性检测中，AILb-A以剂量依赖的方式诱导TLR4细胞的NF-kappaB激活，但对TLR2基因的细胞无此作用。在无血清条件下，AILb-A可诱导TLR4介导的NF-kappaB活化，而脂多糖(LPS)不能诱导其活化。在人外周血单个核细胞的体外实验中，抗TLR4抗体对AILb-A诱导的细胞因子产生有明显的抑制作用，而抗CD14抗体和抗TLR4抗体对内毒素诱导的TLR4诱导的细胞因子产生均有抑制作用。AILb-A诱导的细胞因子产生、杀伤细胞活性、树突状细胞成熟、丝裂原活化蛋白激酶的磷酸化和干扰素调节因子3的核转位在TLR4缺陷小鼠中严重受损，但在TLR2缺陷小鼠中没有。将TLR4表达载体导入TLR4缺陷小鼠来源的巨噬细胞，可诱导AILb-A产生细胞因子。最后，在TLR4缺陷和TLR4突变的小鼠中，AILb-A的抗肿瘤作用也受到损害。这些发现表明，TLR4介导了植物源性蛋白AILb-A诱导的抗肿瘤免疫。
A 55-kDa protein named AILb-A, isolated from the seed extract of Aeginetia indica L., a parasitic plant, induces a Th1-type T-cell response and elicits a marked antitumor effect in tumor-bearing mice. In the present study, we examined the role of Toll-like receptors (TLRs), which have been implicated in pathogen-induced cell signaling, in AILb-A-induced immune responses. In the luciferase assay using a nuclear factor (NF)-kappaB-dependent reporter plasmid, AILb-A induced NF-kappaB activation in the cells transfected with TLR4, but not with those transfected with the TLR2 gene, in a dose-dependent manner. TLR4-mediated NF-kappaB activation induced by AILb-A but not by lipopolysaccharide (LPS) was also observed under serum-free conditions. In in vitro experiments using human peripheral blood mononuclear cells, AILb-A-induced cytokine production was markedly inhibited by anti-TLR4 but not by anti-CD14 antibody, while LPS-induced, TLR4-mediated cytokine production was inhibited by anti-CD14 as well as anti-TLR4 antibodies. Cytokine production, killer cell activities, maturation of dendritic cells, phosphorylation of mitogen-activated protein kinases, and nuclear translocation of interferon-regulatory factor 3 induced by AILb-A were severely impaired in TLR4-deficient but not TLR2-deficient mice. Transfection of TLR4-deficient mouse-derived macrophages with the TLR4 expression plasmid led AILb-A to induce cytokines. Finally, the antitumor effect of AILb-A was also impaired in TLR4-deficient and TLR4-mutated mice. These findings suggest that TLR4 mediates antitumor immunity induced by the plant-derived protein AILb-A.