Helicobacter pylori disrupts STAT1-mediated gamma interferon-induced signal transduction in epithelial cells
Helicobacter pylori disrupts STAT1-mediated gamma interferon-induced signal transduction in epithelial cells
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DOI：
10.1128/iai.72.1.537-545.2004
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发表时间：
2004-01-01
影响因子：
3.1
通讯作者：
Sherman, PM
中科院分区：
文献类型：
--
作者：
Mitchell, DJ;Huynh, HQ;Sherman, PM
幽门螺杆菌感染是慢性的，尽管有强烈的粘膜免疫反应，其特征是胃t辅助型1细胞扩增和γ干扰素（ifn - γ）的产生。ifn - γ信号的激活和核易位的信号换能器和转录激活子1 (STAT1)；然而，幽门螺杆菌感染对ifn - γ - stat1信号的影响尚不清楚。我们用I型和2型幽门螺杆菌感染人胃（MKN45和AGS）和喉（HEp-2）上皮细胞系，然后用ifn - γ刺激它们。全细胞蛋白提取物的Western blotting结果显示，感染活的（而不是热灭活的）幽门螺杆菌可减少ifn - γ诱导的STAT1酪氨酸磷酸化。核蛋白提取物的电泳迁移迁移试验表明，幽门螺杆菌感染降低了ifn - γ诱导的STAT1 DNA结合。免疫荧光检测幽门螺杆菌感染的HEp-2细胞中，STAT1无法从细胞质转移到细胞核，逆转录- pcr显示ifn - γ诱导的干扰素调节因子I的表达受到抑制。这些影响与感染幽门螺杆菌菌株的cagA、cagE和VacA状态无关。此外，幽门螺杆菌培养上清液和幽门螺杆菌感染的MKN45细胞的条件培养基都没有抑制ifn - γ诱导的STAT1酪氨酸磷酸化，这表明抑制与可溶性上皮或细菌因子无关，而是依赖于细菌与上皮细胞的接触。幽门螺杆菌破坏上皮细胞中的ifn - γ - stat1信号可能是细菌改变粘膜免疫反应以促进其在人类宿主中存活的一种机制。
Infection with Helicobacter pylori is chronic despite a vigorous mucosal immune response characterized by gastric T-helper type 1 cell expansion and gamma interferon (IFN-gamma) production. IFN-gamma signals by activation and nuclear translocation of signal transducer and activator of transcription 1 (STAT1); however, the effect of H. pylori infection on IFN-gamma-STAT1 signaling is unknown. We infected human gastric (MKN45 and AGS) and laryngeal (HEp-2) epithelial cell lines with type I and type 2 H. pylori strains and then stimulated them with IFN-gamma. Western blotting of whole-cell protein extracts revealed that infection with live, but not heat-killed, H. pylori time-dependently decreased IFN-gamma-induced STAT1 tyrosine phosphorylation. Electrophoretic mobility shift assay of nuclear protein extracts demonstrated that H. pylori infection reduced IFN-gamma-induced STAT1 DNA binding. STAT1 was unable to translocate from the cytoplasm to the nucleus in H. pylori-infected HEp-2 cells examined by immunofluorescence, and reverse transcription-PCR showed that IFN-gamma-induced interferon regulatory factor I expression was inhibited. These effects were independent of the cagA, cagE, and VacA status of the infecting H. pylori strain. Furthermore, neither H. pylori culture supernatants nor conditioned medium from H. pylori-infected MKN45 cells inhibited IFN-gamma-induced STAT1 tyrosine phosphorylation, suggesting that inhibition is independent of a soluble epithelial or bacterial factor but is dependent on bacterial contact with epithelial cells. H. pylori disruption of IFN-gamma-STAT1 signaling in epithelial cells may represent a mechanism by which the bacterium modifies mucosal immune responses to promote its survival in the human host.