Eotaxin is specifically cleaved by hookworm metalloproteases preventing its action in vitro and in vivo
Eotaxin is specifically cleaved by hookworm metalloproteases preventing its action in vitro and in vivo
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DOI：
10.4049/jimmunol.165.11.6447
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发表时间：
2000-12-01
影响因子：
4.4
通讯作者：
Williams, TJ
中科院分区：
文献类型：
--
作者：
Culley, FJ;Brown, A;Williams, TJ
嗜酸性粒细胞趋化因子是一种有效的嗜酸性粒细胞化学引诱剂，通过 CCR3 选择性起作用，CCR3 在嗜酸性粒细胞、嗜碱性粒细胞、肥大细胞和 Th2 型 T 细胞上表达。据信，免疫系统的这一臂已经进化到控制蠕虫寄生虫。我们假设蠕虫可能采用抑制嗜酸性粒细胞募集的机制，以延长蠕虫在宿主体内的存活时间。我们观察到，美洲钩虫的排泄/分泌产物响应嗜酸性粒细胞趋化因子而抑制体内嗜酸性粒细胞的募集，但不抑制白三烯 B-4，这种现象可以通过添加蛋白酶抑制剂来预防。使用蛋白质印迹法，N, americanus 上清液被证明可引起嗜酸细胞趋化因子的快速蛋白水解，但不会引起 IL-8 或嗜酸细胞趋化因子-2，N, 美洲属匀浆通过凝胶过滤色谱进行分级，并且基于 FAGS 的生物测定法测量了每个级分抑制多种趋化因子活性的能力，这导致了嗜酸细胞趋化因子降解活性的两个峰，对应于类似于 15 和 50 kDa 分子质量。该活性对嗜酸细胞活化趋化因子具有特异性，因为对其他测试激动剂的反应不受影响。 EDTA 和菲咯啉阻止嗜酸细胞活化趋化因子的蛋白水解，表明金属蛋白酶活性参与其中。产生灭活嗜酸性粒细胞趋化因子的酶可能是蠕虫用来防止感染部位嗜酸性粒细胞募集和活化的策略。因此，这代表了体内趋化因子功能调节的新机制。除嗜酸细胞趋化因子（例如嗜酸细胞趋化因子2）以外的CCR3配体的存在可能反映了宿主对抗寄生虫防御系统的措施的演变。
Eotaxin is a potent eosinophil chemoattractant that acts selectively through CCR3, which is expressed on eosinophils, basophils, mast cells, and Th2-type T cells, This arm of the immune system is believed to have evolved to control helminthic parasites. We hypothesized that helminths may employ mechanisms to inhibit eosinophil recruitment, to prolong worm survival in the host. We observed that the excretory/secretory products of the hookworm Necator americanus inhibited eosinophil recruitment in vivo in response to eotaxin, but not leukotriene B-4, a phenomenon that could be prevented by the addition of protease inhibitors. Using Western blotting, N, americanus supernatant was shown to cause rapid proteolysis of eotaxin, but not IL-8 or eotaxin-2, N, americanus homogenate was fractionated by gel filtration chromatography, and a FAGS-based bioassay measured the ability of each fraction to inhibit the activity of a variety of chemokines, This resulted in two peaks of eotaxin-degrading activity, corresponding to similar to 15 and 50 kDa molecular mass. This activity was specific for eotaxin, as responses to other agonists tested were unaffected. Proteolysis of eotaxin was prevented by EDTA and phenanthroline, indicating that metalloprotease activity was involved. Production of enzymes inactivating eotaxin may be a strategy employed by helminths to prevent recruitment and activation of eosinophils at the site of infection. As such this represents a novel mechanism of regulation of chemokine function in vivo. The existence of CCR3 ligands other than eotaxin (e.g., eotaxin-2) may reflect the evolution of host counter measures to parasite defense systems.