Internalization and phagosome escape required for Francisella to induce human monocyte IL-1β processing and release
Internalization and phagosome escape required for Francisella to induce human monocyte IL-1β processing and release
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DOI：
10.1073/pnas.0504271103
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发表时间：
2006-01-03
影响因子：
11.1
通讯作者：
Wewers, MD
中科院分区：
文献类型：
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作者：
Gavrilin, MA;Bouakl, IJ;Wewers, MD
巨噬细胞对弗朗西斯菌感染的反应以前的特征是抑制促炎反应;然而，这些研究通常集中在巨噬细胞系或单核细胞衍生的巨噬细胞上。因此，我们研究了新鲜人血单核细胞的吞噬能力，并通过使用活疫苗株变异体和新杀弗朗西斯菌响应。由于弗朗西斯菌生物体已被报道从吞噬溶酶体逃逸到胞质溶胶中，我们假设这种逃逸可能触发caspase-1的激活。土拉热弗朗西斯菌变体容易被新鲜的人CD 14+单核细胞吸收，以时间和剂量依赖性方式诱导IL-1 β以及IL-8的释放。重要是，尽管活的和死的大肠杆菌、F. novicida和活疫苗株以及E.大肠杆菌（F. coli）能诱导大量IL-1 β mRNA合成和细胞内IL-1 β前体的产生，只有活的弗朗西斯氏菌（Francisella）能诱导增强的IL-1 β加工和释放（51 ± 10对7.1 ± 2.1 ng/ml，F. coli）。novicida vs. coli LPS; P = 0.0032）。细胞松弛素D阻断了Francisella的内化和Francisella诱导的单核细胞IL-1 β的加工和释放，但不能阻断外源性刺激E coli LIPS诱导的IL-1 β的加工和释放。此外，杀死细菌并不阻止摄取，但显著减少了弗朗西斯诱导的IL-1 β加工和释放。阻断细菌从吞噬体逃逸到胞质溶胶中也降低了IL-1 β的释放，但不降低IL-8的释放。这些发现表明，弗朗西斯菌属生物体通过需要摄取能够吞噬体逃逸的活细菌的传感系统在新鲜单核细胞中有效诱导IL-1 β加工和释放。
Macrophage responses to Francisella infection have been characterized previously by subdued proinflammatory responses; however, these studies have generally focused on macrophage cell lines or monocyte-derived macrophages. Therefore, we studied the ability of fresh human blood monocytes to engulf and respond to Franciselia by using the live vaccine strain variant and Francisella novicida. Because Francisella organisms have been reported to escape from the phagolysosome into the cytosol, we hypothesized that this escape may trigger the activation of caspase-1. Franciselia tularensis variants were readily taken up by fresh human CD14+ monocytes, inducing the release of IL-1 beta, as well as IL-8, in a time-and dose-dependent fashion. importantly, whereas live and dead Escherichia coli, F. novicida, and live vaccine strain, as well as the LPS of E. coli, were able to induce abundant IL-1 beta mRNA synthesis and intracellular pro-IL-1 beta production, only live Francisella induced enhanced IL-1 beta processing and release (51 +/- 10 vs. 7.1 +/- 2.1 ng/ml, for F. novicida vs. E. coli LPS; P = 0.0032). Cytochalasin D blocked the Franciselia internalization and the Francisella-induced monocyte IL-1 beta processing and release but not that induced by the exogenous stimulus E coli LIPS. Also, killing bacteria did not block uptake but significantly diminished the IL-1 beta processing and release that was induced by Franciselial. Blocking bacterial escape from the phagosome into the cytosol also decreased IL-1 beta but not IL-8 release. These findings demonstrate that Francisella organisms efficiently induce IL-1 beta processing and release in fresh monocytes by means of a sensing system that requires the uptake of live bacteria capable of phagosome escape.