Department of Pathology, Microbiology, and Immunology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
Immunopharmacology Research Laboratory, Institute of Biology, College of Science, University of the Philippines, Diliman, Philippines.
mBio. 2024 Oct 16;15(10):e0183424. doi: 10.1128/mbio.01834-24. Epub 2024 Aug 28.
has adapted to subvert signaling in epithelial cells to ensure successful intracellular development. Interferon-γ (IFNγ) produced by recruited lymphocytes signals through the JAK/STAT pathway to restrict chlamydial growth in the genital tract. However, during infection , addition of IFNγ does not fully induce nuclear localization of its transcription factor STAT1 and expression of its target gene, IDO1. We hypothesize that this altered interferon response is a result of targeting components of the IFNγ-JAK/STAT pathway. To assess the ability of replicating to dampen interferon signaling, HEp2 human epithelial cells were infected with serovar L2 for 24 hours prior to exposure to physiologically relevant levels of IFNγ (500 pg/mL). This novel approach enabled us to observe reduced phospho-activation of both STAT1 and its kinase Janus Kinase 2 (JAK2) in infected cells compared with mock-infected cells. Importantly, basal JAK2 and STAT1 transcript and protein levels were dampened by infection even in the absence of interferon, which could have implications for cytokine signaling beyond IFNγ. Additionally, target genes IRF1, GBP1, APOL3, IDO1, and SOCS1 were not fully induced in response to IFNγ exposure. Infection-dependent decreases in transcript, protein, and phosphoprotein were rescued when bacterial protein synthesis was inhibited with chloramphenicol, restoring expression of IFNγ-target genes. Similar -dependent dampening of STAT1 and JAK2 transcript levels was observed in infected HeLa and END1 endocervical cells and in HEp2s infected with serovar D, suggesting a conserved mechanism of dampening the interferon response by reducing the availability of key signaling components.
As an obligate intracellular pathogen that has evolved to infect the genital epithelium, has developed strategies to prevent detection and antimicrobial signaling in its host to ensure its survival and spread. A major player in clearing infections is the inflammatory cytokine interferon-γ (IFNγ), which is produced by immune cells that are recruited to the site of infection. Reports of IFNγ levels in endocervical specimens from -infected patients range from 1 to 350 pg/mL, while most studies of the effects of IFNγ on chlamydial growth have used 15-85-fold higher concentrations. By using physiologically relevant concentrations of IFNγ, we were able to assess 's ability to modulate its signaling. We found that decreases the expression of multiple components that are required for inducing gene expression by IFNγ, providing a possible mechanism by which can attenuate the immune response in the female genital tract to cause long-term infections.
已适应颠覆上皮细胞中的信号转导，以确保其在细胞内的成功发育。募集的淋巴细胞产生的干扰素 -γ（IFNγ）通过 JAK/STAT 途径发出信号，以限制生殖道中衣原体的生长。然而，在 感染期间，添加 IFNγ并不能完全诱导其转录因子 STAT1 的核定位和其靶基因 IDO1 的表达。我们假设这种改变的干扰素反应是针对 IFNγ-JAK/STAT 途径的成分的结果。为了评估复制的 的能力来抑制干扰素信号，在用生理相关浓度的 IFNγ（500pg/mL）处理之前，用 血清型 L2 感染 HEp2 人上皮细胞 24 小时。这种新方法使我们能够观察到与模拟感染细胞相比，感染细胞中 STAT1 和其激酶 Janus Kinase 2（JAK2）的磷酸化激活减少。重要的是，即使在没有干扰素的情况下，感染也会抑制基础 JAK2 和 STAT1 转录本和蛋白水平，这可能对 IFNγ 以外的细胞因子信号转导产生影响。此外，靶基因 IRF1、GBP1、APOL3、IDO1 和 SOCS1 并未完全响应 IFNγ 暴露而被诱导。用氯霉素抑制 细菌蛋白合成后，感染依赖性的转录本、蛋白和磷酸蛋白减少得到恢复，从而恢复 IFNγ 靶基因的表达。在感染的 HeLa 和 END1 宫颈细胞以及感染 血清型 D 的 HEp2s 中观察到类似的 STAT1 和 JAK2 转录本水平的抑制，表明通过减少关键信号成分的可用性来抑制干扰素反应的保守机制。
作为一种已进化为感染生殖道上皮细胞的专性细胞内病原体， 已开发出策略来防止宿主中检测和抗菌信号，以确保其存活和传播。清除 感染的主要参与者是炎症细胞因子干扰素 -γ（IFNγ），它是被募集到感染部位的免疫细胞产生的。来自 -感染患者的宫颈标本中 IFNγ 水平的报告范围为 1 至 350pg/mL，而大多数关于 IFNγ 对衣原体生长影响的研究使用的浓度是其 15-85 倍。通过使用生理相关浓度的 IFNγ，我们能够评估 的调节其信号的能力。我们发现， 降低了诱导 IFNγ 诱导基因表达所需的多个成分的表达，这为 如何减轻女性生殖道中的免疫反应以导致长期感染提供了一个可能的机制。
