Beta Interferon-Mediated Activation of Signal Transducer and Activator of Transcription Protein 1 Interferes with Rickettsia conorii Replication in Human Endothelial Cells
Beta Interferon-Mediated Activation of Signal Transducer and Activator of Transcription Protein 1 Interferes with Rickettsia conorii Replication in Human Endothelial Cells
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DOI：
10.1128/iai.05008-11
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发表时间：
2011-09-01
影响因子：
3.1
通讯作者：
Sahni, Sanjeev K.
中科院分区：
文献类型：
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作者：
Colonne, Punsiri M.;Eremeeva, Marina E.;Sahni, Sanjeev K.
康氏立克次体（地中海斑疹热的病原体）对血管内皮细胞内壁的感染会导致内皮细胞活化。根据体内立克次体对微血管内皮的趋向性，我们研究了康氏立克次体感染对人微血管内皮细胞（HMEC）（最相关的宿主细胞类型）中 Janus 激酶（JAK）信号转导器和转录蛋白激活剂（STAT）信号通路状态的影响。 R. conorii 感染在 HMEC 中感染后 24、48 和 72 小时诱导 STAT1 在酪氨酸 701 和丝氨酸 727 上的磷酸化。利用转录谱分析和中和抗体，我们进一步确定β干扰素 (IFN-β) 的产生和分泌对于 STAT1 激活至关重要。分泌的 IFN-β 通过正反馈机制进一步放大其自身表达，同时还诱导参与 IFN-β-STAT1 反馈环路的转录因子干扰素调节因子 7 (IRF7) 和 IRF9 的表达。立克次体的代谢活性对于 IFN-β 介导的反应至关重要，因为四环素治疗抑制立克次体复制、IFN-β 表达和 STAT1 磷酸化。感染期间加入 IFN-β 中和抗体可显着增强 R. conorii 的复制，而添加外源 IFN-β 则具有相反的抑制作用。最后，小干扰 RNA 介导的敲低进一步证实了 STAT1 对胞内 R. conorii 复制的保护作用。总之，这些发现表明 IFN-β 介导的 STAT1 激活在血管内皮对 R. conorii 感染的先天免疫反应中发挥着重要作用。
Infection of the endothelial cell lining of blood vessels with Rickettsia conorii, the causative agent of Mediterranean spotted fever, results in endothelial activation. We investigated the effects of R. conorii infection on the status of the Janus kinase (JAK)-signal transducer and activator of transcription protein (STAT) signaling pathway in human microvascular endothelial cells (HMECs), the most relevant host cell type, in light of rickettsial tropism for microvascular endothelium in vivo. R. conorii infection induced phosphorylation of STAT1 on tyrosine 701 and serine 727 at 24, 48, and 72 h postinfection in HMECs. Employing transcription profile analysis and neutralizing antibodies, we further determined that beta interferon (IFN-beta) production and secretion are critical for STAT1 activation. Secreted IFN-beta further amplified its own expression via a positive-feedback mechanism, while expression of transcription factors interferon regulatory factor 7 (IRF7) and IRF9, implicated in the IFN-beta-STAT1 feedback loop, was also induced. Metabolic activity of rickettsiae was essential for the IFN-beta-mediated response(s) because tetracycline treatment inhibited R. conorii replication, IFN-beta expression, and STAT1 phosphorylation. Inclusion of IFN-beta-neutralizing antibody during infection resulted in significantly enhanced R. conorii replication, whereas addition of exogenous IFN-beta had the opposite inhibitory effect. Finally, small interfering RNA-mediated knockdown further confirmed a protective role for STAT1 against intracellular R. conorii replication. In concert, these findings implicate an important role for IFN-beta-mediated STAT1 activation in innate immune responses of vascular endothelium to R. conorii infection.