Pu Xianglin, Zhang Yiyuan, Huang Xinmei, Lu Mingmin, Xu Lixin, Yan Ruofeng, Li Xiangrui, Song Xiaokai
Ministry of Education (MOE) Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Science, Nanjing, 210014, China.
Vet Res. 2025 May 19;56(1):103. doi: 10.1186/s13567-025-01535-7.
Eimeria maxima (E. maxima) infection inhibits the expression of IFN-γ, a cytokine that is essential for the Th1 immune response and plays a key role in combating this parasite. In our preliminary investigations, we identified the E. maxima surface antigen (EmSAG) as an inhibitory molecule of IFN-γ. EmSAG was screened and characterised from an E. maxima sporozoite cDNA expression library. The present study aimed to evaluate the immunomodulatory effects of EmSAG on chicken peripheral blood mononuclear cells (PBMCs) and various T cell subsets. We analysed cell proliferation, nitric oxide (NO) release, and cytokine transcription. The results revealed that EmSAG boosts PBMC proliferation and promotes differentiation of CD4/CD8 T cells. Additionally, stimulation with EmSAG significantly inhibited NO release and IFN-γ transcription while enhancing the transcription of IL-4, IL-10, and TGF-β1 in chicken PBMCs. The sorting purity of T cell subsets was as follows: CD8 (96.90%), CD4 (86.25%), CD4CD25 (89.14%), and CD4CD25 regulatory T cells (Tregs; 92.16%). These purified subsets were co-incubated with EmSAG to analyse the transcription of hallmark cytokines associated with Th1, Th2, and Treg responses. EmSAG significantly inhibited the transcription of IFN-γ and IL-2 in both CD4 and CD8 T cells, while promoting the expression of IL-10, TGF-β1, and CTLA-4 in Tregs. Moreover, depletion of CD25 cells reversed the EmSAG-induced suppression of IL-2 transcription and reduced its stimulating effects on IL-4 and IL-10 transcription in CD4CD25 T cells. These findings highlight the role of EmSAG as an inhibitor of IFN-γ, facilitating immune evasion by attenuating the Th1 immune response and modulating Treg cell function. This study provides critical insights into the immune evasion mechanisms utilised by chicken coccidia.
巨型艾美耳球虫（E. maxima）感染会抑制γ干扰素（IFN-γ）的表达，γ干扰素是一种对Th1免疫反应至关重要的细胞因子，在对抗这种寄生虫中起关键作用。在我们的初步研究中，我们鉴定出巨型艾美耳球虫表面抗原（EmSAG）是IFN-γ的抑制分子。从巨型艾美耳球虫子孢子cDNA表达文库中筛选并鉴定了EmSAG。本研究旨在评估EmSAG对鸡外周血单个核细胞（PBMCs）和各种T细胞亚群的免疫调节作用。我们分析了细胞增殖、一氧化氮（NO）释放和细胞因子转录。结果显示，EmSAG促进PBMC增殖并促进CD4/CD8 T细胞分化。此外，用EmSAG刺激显著抑制鸡PBMCs中NO释放和IFN-γ转录，同时增强IL-4、IL-10和TGF-β1的转录。T细胞亚群的分选纯度如下：CD8（96.90%）、CD4（86.25%）、CD4CD25（89.14%）和CD4CD25调节性T细胞（Tregs；92.16%）。将这些纯化的亚群与EmSAG共同孵育，以分析与Th1、Th2和Treg反应相关的标志性细胞因子的转录。EmSAG显著抑制CD4和CD8 T细胞中IFN-γ和IL-2的转录，同时促进Tregs中IL-10、TGF-β1和CTLA-4的表达。此外，去除CD25细胞可逆转EmSAG诱导的IL-2转录抑制，并降低其对CD4CD25 T细胞中IL-4和IL-10转录的刺激作用。这些发现突出了EmSAG作为IFN-γ抑制剂的作用，通过减弱Th1免疫反应和调节Treg细胞功能促进免疫逃避。本研究为鸡球虫利用的免疫逃避机制提供了重要见解。
