Geng Xiaoyu, Yao Tiankun, Wang Xinyue, Wang Jianan, Zhang Tongrui, Qian Tianmei, Liu Chun, Chen Jinling
Department of Pathogen Biology, School of Medicine, Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, People's Republic of China.
Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
Parasit Vectors. 2025 Jul 1;18(1):245. doi: 10.1186/s13071-025-06894-w.
BACKGROUND: Approximately one in three people worldwide have been exposed to Toxoplasma gondii (T. gondii). Primary infection with T. gondii during pregnancy can cause severe complications. Our previous study demonstrated that deficiency of triggering receptor expressed on myeloid cells 2 (Trem2) exacerbates pregnancy-related complications in T. gondii-infected mice. However, understanding the mechanisms by which T. gondii modulates Trem2 expression in macrophages remains an unmet challenge. METHODS: A mouse pregnancy model of T. gondii infection and an in vitro cellular stimulation model using soluble T. gondii antigens (sTgAg) were used to assess Trem2 expression. Recombinant plasmids containing the full-length Trem2 promoter were constructed to evaluate the effect of sTgAg on promoter activity, followed by the construction of truncated promoter plasmids to identify key regulatory regions. Transcription factors potentially binding to the Trem2 promoter were predicted using PROMO and JASPAR, with ATF3 identified as responsive to sTgAg stimulation via western blot analysis. The binding of ATF3 to the Trem2 promoter was validated by chromatin immunoprecipitation (ChIP) assays. Finally, ATF3 knockdown experiments were performed to determine its role in mediating the inhibitory effect of sTgAg on Trem2 expression. RESULTS: T. gondii significantly suppressed Trem2 expression in both mouse placentas and cellular models, with truncated promoter assays identifying key regulatory regions of the Trem2 promoter inhibited by sTgAg. ATF3 was identified as a transcription factor responsive to sTgAg stimulation, which bound to the Trem2 promoter. Importantly, knockdown of ATF3 restored Trem2 expression, demonstrating its critical role in mediating the inhibitory effect of sTgAg. CONCLUSIONS: We identified that sTgAg may target and inhibit Trem2 expression through the transcription factor ATF3, and inhibition of ATF3 activity may help maintain Trem2 expression in macrophages, providing a potential therapeutic approach to avert negative effects on pregnancy related to T. gondii infection.
背景：全球约三分之一的人曾接触过刚地弓形虫（T. gondii）。孕期初次感染刚地弓形虫可导致严重并发症。我们之前的研究表明，髓系细胞2（Trem2）上表达的触发受体缺陷会加剧刚地弓形虫感染小鼠的妊娠相关并发症。然而，了解刚地弓形虫调节巨噬细胞中Trem2表达的机制仍是一项尚未解决的挑战。 方法：使用刚地弓形虫感染的小鼠妊娠模型和使用可溶性刚地弓形虫抗原（sTgAg）的体外细胞刺激模型来评估Trem2表达。构建含有全长Trem2启动子的重组质粒以评估sTgAg对启动子活性的影响，随后构建截短的启动子质粒以鉴定关键调控区域。使用PROMO和JASPAR预测可能与Trem2启动子结合的转录因子，通过蛋白质印迹分析确定ATF3对sTgAg刺激有反应。通过染色质免疫沉淀（ChIP）试验验证ATF3与Trem2启动子的结合。最后，进行ATF3敲低实验以确定其在介导sTgAg对Trem2表达的抑制作用中的作用。 结果：刚地弓形虫显著抑制小鼠胎盘和细胞模型中的Trem2表达，截短启动子试验确定了Trem2启动子中受sTgAg抑制的关键调控区域。ATF3被鉴定为对sTgAg刺激有反应的转录因子，它与Trem2启动子结合。重要的是，敲低ATF3可恢复Trem2表达，证明其在介导sTgAg抑制作用中的关键作用。 结论：我们发现sTgAg可能通过转录因子ATF3靶向并抑制Trem2表达，抑制ATF3活性可能有助于维持巨噬细胞中Trem2的表达，为避免刚地弓形虫感染对妊娠产生负面影响提供了一种潜在的治疗方法。
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