P2X7 Receptor Regulates Internalization of Antimicrobial Peptide LL-37 by Human Macrophages That Promotes Intracellular Pathogen Clearance
P2X7 Receptor Regulates Internalization of Antimicrobial Peptide LL-37 by Human Macrophages That Promotes Intracellular Pathogen Clearance
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DOI：
10.4049/jimmunol.1402845
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发表时间：
2015-08-01
影响因子：
4.4
通讯作者：
Wan, Min
中科院分区：
文献类型：
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作者：
Tang, Xiao;Basavarajappa, Devaraj;Wan, Min
生物活性肽LL-37/hCAP 18是cathelicidin家族中唯一的人类成员，在杀死各种病原体以及免疫调节中起重要作用。我们证明，LL-37是内化的人巨噬细胞在时间，剂量，温度和肽序列依赖性的内吞过程。网格蛋白和小窝/脂筏介导的内吞途径都参与LL-37的内化。我们发现P2 X（7）受体（P2 X（7）R）在LL-37被人巨噬细胞内化中起重要作用，因为在用P2 X（7）R拮抗剂预处理的巨噬细胞中，或者更具体地说，在P2 X（7）R基因已被沉默的分化的THP-1细胞中，检测到显著较少的内化LL-37。此外，这种P2 X（7）R介导的LL-37内化主要与网格蛋白介导的内吞途径有关。此外，我们的结果表明，内化的LL-37运输到内体和溶酶体，并有助于通过人巨噬细胞的细菌细胞内清除，与增加的活性氧和溶酶体形成一致。最后，我们表明，人类巨噬细胞有潜力进口LL-37释放激活的人中性粒细胞。总之，我们的研究揭示了一种新的机制，人类巨噬细胞内化抗菌肽，以提高其细胞内的病原体清除。
Bioactive peptide LL-37/hCAP18, the only human member of the cathelicidin family, plays important roles in killing various pathogens, as well as in immune modulation. We demonstrate that LL-37 is internalized by human macrophages in a time-, dose-, temperature-, and peptide sequence-dependent endocytotic process. Both clathrin-and caveolae/lipid raft-mediated endocytosis pathways are involved in LL-37 internalization. We find that the P2X(7) receptor (P2X(7)R) plays an important role in LL-37 internalization by human macrophages because significantly less internalized LL-37 was detected in macrophages pretreated with P2X(7)R antagonists or, more specifically, in differentiated THP-1 cells in which the P2X(7)R gene had been silenced. Furthermore, this P2X(7)R-mediated LL-37 internalization is primarily connected to the clathrin-mediated endocytosis pathway. In addition, our results demonstrate that internalized LL-37 traffics to endosomes and lysosomes and contributes to intracellular clearance of bacteria by human macrophages, coinciding with increased reactive oxygen species and lysosome formation. Finally, we show that human macrophages have the potential to import LL-37 released from activated human neutrophils. In conclusion, our study unveils a novel mechanism by which human macrophages internalize antimicrobial peptides to improve their intracellular pathogen clearance.