滋养层细胞产生的 IL-10 抑制吞噬体成熟，导致鼠伤寒沙门氏菌的体内增殖。
IL-10 produced by trophoblast cells inhibits phagosome maturation leading to profound intracellular proliferation of Salmonella enterica Typhimurium.
机构信息
Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, ON, Canada.
出版信息
Placenta. 2013 Sep;34(9):765-74. doi: 10.1016/j.placenta.2013.06.003. Epub 2013 Jul 5.
INTRODUCTION
Salmonella enterica Typhimurium (ST) is a phagosomal pathogen that can infect placental trophoblast cells leading to abortion and severe maternal illness. It is unclear how the trophoblast cells promote profound bacterial proliferation.
METHODS
The mechanism of internalization, intracellular growth and phagosomal biogenesis in ST-infected human epithelial (HeLa), macrophage (THP-1) and trophoblast-derived cell lines (JEG-3, BeWo and HTR-8) was studied. Specific inhibitors were used to block bacterial internalization. Phagosomal maturation was determined by confocal microscopy, Western-blotting and release of lysosomal β-galactosidase by infected cells. Bacterial colony forming units were determined by plating infected cell lysates on agar plates.
RESULTS
ST proliferated minimally in macrophages but replicated profoundly within trophoblast cells. The ST-ΔinvA (a mutant of Salmonella pathogenicity island-1 gene effector proteins) was unable to infect epithelial cells, but was internalized by scavenger receptors on trophoblasts and macrophages. However, ST was contrastingly localized in early (Rab5⁺) or late (LAMP1⁺) phagosomes within trophoblast cells and macrophages respectively. Furthermore trophoblast cells (unlike macrophages) did not exhibit phagoso-lysosomal fusion. ST-infected macrophages produced IL-6 whereas trophoblast cells produced IL-10. Neutralizing IL-10 in JEG-3 cells accelerated phagolysomal fusion and reduced proliferation of ST. Placental bacterial burden was curtailed in vivo in anti-IL-10 antibody treated and IL-10-deficient mice.
DISCUSSION
Macrophages phagocytose but curtail intracellular replication of ST in late phagosomes. In contrast, phagocytosis by trophoblast cells results in an inappropriate cytokine response and proliferation of ST in early phagosomes.
CONCLUSION
IL-10 production by trophoblast cells that delays phagosomal maturation may facilitate proliferation of pathogens in placental cells.
简介
鼠伤寒沙门氏菌（ST）是一种吞噬体病原体，可感染胎盘滋养层细胞，导致流产和严重的母体疾病。目前尚不清楚滋养层细胞如何促进细菌的大量增殖。
方法
研究了 ST 感染人上皮（HeLa）、巨噬细胞（THP-1）和滋养层衍生细胞系（JEG-3、BeWo 和 HTR-8）的内化、细胞内生长和吞噬体生物发生的机制。使用特定抑制剂阻断细菌内化。通过共聚焦显微镜、Western-blotting 和感染细胞释放溶酶体β-半乳糖苷酶来确定吞噬体成熟。通过在琼脂平板上接种感染细胞裂解物来确定细菌集落形成单位。
结果
ST 在巨噬细胞中增殖很少，但在滋养层细胞中大量复制。ST-ΔinvA（沙门氏菌致病性岛-1 基因效应蛋白突变体）无法感染上皮细胞，但可被滋养层细胞和巨噬细胞上的清道夫受体内化。然而，ST 在滋养层细胞和巨噬细胞中的内化情况分别位于早期（Rab5⁺）或晚期（LAMP1⁺）吞噬体中。此外，滋养层细胞（与巨噬细胞不同）没有表现出吞噬溶酶体融合。ST 感染的巨噬细胞产生 IL-6，而滋养层细胞产生 IL-10。在 JEG-3 细胞中中和 IL-10 加速了吞噬溶酶体融合并减少了 ST 的增殖。体内用抗 IL-10 抗体治疗和 IL-10 缺陷小鼠可减少胎盘细菌负荷。
讨论
巨噬细胞吞噬 ST，但在晚期吞噬体中抑制其细胞内复制。相比之下，滋养层细胞的吞噬作用导致了不适当的细胞因子反应和早期吞噬体中 ST 的增殖。
结论
滋养层细胞产生的 IL-10 延迟吞噬体成熟，可能有助于病原体在胎盘细胞中的增殖。
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