Inhibitory effect of toll-like receptor 4 on fusion between phagosomes and endosomes/lysosomes in macrophages
Inhibitory effect of toll-like receptor 4 on fusion between phagosomes and endosomes/lysosomes in macrophages
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DOI：
10.4049/jimmunol.172.4.2039
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发表时间：
2004-02-15
影响因子：
4.4
通讯作者：
Nakanishi, Y
中科院分区：
文献类型：
--
作者：
Shiratsuchi, A;Watanahe, I;Nakanishi, Y
巨噬细胞的Toll样受体4（TLR 4）与CD 14协同识别革兰氏阴性菌的LPS，CD 14也参与识别凋亡细胞。在这项研究中，我们询问TLR 4是否在巨噬细胞对凋亡细胞的吞噬清除中起作用。巨噬细胞从巯基乙酸处理的携带野生型或破坏的TLR 4编码基因的小鼠的腹腔液中制备，并检查其吞噬凋亡小鼠胸腺细胞、凋亡Jurkat T细胞、Ig调理的小鼠胸腺细胞、Ig调理的酵母聚糖颗粒和乳胶珠的能力。两个群体的巨噬细胞同样表达的CD 14在其表面上，并显示出几乎相同的活动，结合和吞噬所有这些目标。然而，凋亡的胸腺细胞，凋亡的Jurkat细胞，和调理胸腺细胞更迅速地消失在TLR 4缺陷型巨噬细胞比野生型巨噬细胞，和内体/溶酶体和吞噬体之间的融合，含有任何靶细胞或颗粒的突变体巨噬细胞加速。野生型巨噬细胞在吞噬后似乎没有发生转录因子NF-κ B的激活，并且无论NF-κ B的激活如何，野生型巨噬细胞中凋亡细胞降解的速率保持不变。最后，免疫组织化学分析表明，异位表达的TLR 4与巨噬细胞来源的细胞系中的吞噬体相关。所有这些结果共同表明，TLR 4通过不依赖于NF-κ B的途径负调节巨噬细胞中吞噬细胞的降解。
Toll-like receptor 4 (TLR4) of macrophages recognizes LPS of Gram-negative bacteria in cooperation with CD14, which is also involved in the recognition of, apoptotic cells. In this study we asked whether TLR4 plays a role in the phagocytic clearance of apoptotic cells by macrophages. Macrophages were prepared from peritoneal fluid of thioglycolate-treated mice carrying either a wild-type or a disrupted TLR4-encoding gene and were examined for their ability to phagocytose apoptotic mouse thymocytes, apoptotic Jurkat T cells, Ig-opsonized mouse thymocytes, Ig-opsonized zymosan particles, and latex beads. Both populations of macrophages equally expressed CD14 on their surfaces and showed almost equal activities of binding to and engulfing all these targets. However, apoptotic thymocytes, apoptotic Jurkat cells, and opsonized thymocytes disappeared more rapidly in TLR4-deficient macrophages than in wild-type macrophages, and the fusion between endosomes/lysosomes and phagosomes containing any target cells or particles was accelerated in mutant macrophages. Activation of the transcription factor NF-kappaB appeared not to occur in wild-type macrophages after engulfment, and the rate of apoptotic cell degradation in wild-type macrophages remained the same regardless of the activation of NF-kappaB Finally, immunohistochemical analyses showed that ectopically expressed TLR4 was associated with phagosomes in a macrophage-derived cell line. All these results collectively indicate that TLR4 negatively regulates the degradation of engulfed cells in macrophages via a pathway independent of NF-kappaB.