Paveley Ross A, Aynsley Sarah A, Cook Peter C, Turner Joseph D, Mountford Adrian P
Department of Biology, The University of York, York, United Kingdom.
PLoS Negl Trop Dis. 2009 Oct 13;3(10):e528. doi: 10.1371/journal.pntd.0000528.
Infection of the mammalian host by the parasitic helminth Schistosoma mansoni is accompanied by the release of excretory/secretory molecules (ES) from cercariae which aid penetration of the skin. These ES molecules are potent stimulants of innate immune cells leading to activation of acquired immunity. At present however, it is not known which cells take up parasite antigen, nor its intracellular fate. Here, we develop a technique to label live infectious cercariae which permits the imaging of released antigens into macrophages (MPhi) and dendritic cells (DCs) both in vitro and in vivo. The amine reactive tracer CFDA-SE was used to efficiently label the acetabular gland contents of cercariae which are released upon skin penetration. These ES products, termed '0-3hRP', were phagocytosed by MHC-II(+) cells in a Ca(+) and actin-dependent manner. Imaging of a labelled cercaria as it penetrates the host skin over 2 hours reveals the progressive release of ES material. Recovery of cells from the skin shows that CFDA-SE labelled ES was initially (3 hrs) taken up by Gr1(+)MHC-II(-) neutrophils, followed (24 hrs) by skin-derived F4/80(+)MHC-II(lo) MPhi and CD11c(+) MHC-II(hi) DC. Subsequently (48 hrs), MPhi and DC positive for CFDA-SE were detected in the skin-draining lymph nodes reflecting the time taken for antigen-laden cells to reach sites of immune priming. Comparison of in vitro-derived MPhi and DC revealed that MPhi were slower to process 0-3hRP, released higher quantities of IL-10, and expressed a greater quantity of arginase-1 transcript. Combined, our observations on differential uptake of cercarial ES by MPhi and DC suggest the development of a dynamic but ultimately balanced response that can be potentially pushed towards immune priming (via DC) or immune regulation (via MPhi).
寄生蠕虫曼氏血吸虫感染哺乳动物宿主时，尾蚴会释放排泄/分泌分子（ES），这些分子有助于穿透皮肤。这些ES分子是先天免疫细胞的强效刺激物，可导致获得性免疫的激活。然而，目前尚不清楚哪些细胞摄取寄生虫抗原，以及其细胞内命运如何。在此，我们开发了一种标记活感染性尾蚴的技术，该技术允许在体外和体内对释放到巨噬细胞（MPhi）和树突状细胞（DC）中的抗原进行成像。胺反应性示踪剂CFDA-SE用于有效标记尾蚴的腹吸盘腺内容物，这些内容物在穿透皮肤时会释放出来。这些ES产物，称为“0-3hRP”，以Ca(+)和肌动蛋白依赖性方式被MHC-II(+)细胞吞噬。对标记尾蚴在2小时内穿透宿主皮肤的成像显示ES物质的逐步释放。从皮肤中回收细胞表明，CFDA-SE标记的ES最初（3小时）被Gr1(+)MHC-II(-)中性粒细胞摄取，随后（24小时）被皮肤来源的F4/80(+)MHC-II(lo) MPhi和CD11c(+) MHC-II(hi) DC摄取。随后（48小时），在引流皮肤的淋巴结中检测到CFDA-SE阳性的MPhi和DC，这反映了载有抗原的细胞到达免疫启动部位所需的时间。对体外培养的MPhi和DC的比较显示，MPhi处理0-3hRP的速度较慢，释放的IL-10量更高，并且表达的精氨酸酶-1转录本量更大。综合来看，我们对MPhi和DC对尾蚴ES的不同摄取的观察结果表明，会形成一种动态但最终平衡的反应，这种反应可能会被推向免疫启动（通过DC）或免疫调节（通过MPhi）。
