Interferon tau (IFNτ) is the main maternal signal for pregnancy in ruminants and modulates the functions of various immune cells, including neutrophils. Neutrophil extracellular traps (NETs) are one of the main defence mechanisms of neutrophils. In this study, we observed higher (p < 0.01) ex-vivo NETs extrusion by blood neutrophils from day 16–18 post artificial insemination (AI) in non-inseminated and inseminated non-pregnant cows compared to pregnant cows. In vitro study also showed that IFNτ hampers NETs formation in dose and time dependent manner. The lowest (p < 0.01) NETs formation and the highest (p < 0.01) mRNA expression (RT-PCR) of IFNτ stimulated genes (ISG15, OAS1, MX1) were observed when neutrophil incubated with 9 ng/mL IFNτ for 3.5 h. Signalling cascades mediating IFNτ impairment of NETs formation were identified using inhibitors of JAK2, JAK3, p38, PI3K/Akt and MAPK/Erk. IFNτ reduced (p < 0.01) the mRNA expression (RT-PCR) and concentration (ELISA) of genes and proteins that mediate NETs formation in blood neutrophils including histones (H1, H2), neutrophil elastase (NE) and myeloperoxidase (MPO). However, the effects of IFNτ on these genes and proteins were eliminated in the presence of JAK3 or PI3K inhibitors. Immunocytochemistry study also showed strong MPO signal in the presence of JAK3 or PI3K inhibitors as compared to positive control (PC, IFNτ alone). The results indicate that IFNτ impairs NETs formation using JAK3 and PI3K and thus essential for successful implantation and establishment of pregnancy in cows.

干扰素 tau (IFNτ) 是反刍动物怀孕的主要母体信号，可调节包括中性粒细胞在内的各种免疫细胞的功能。中性粒细胞胞外陷阱（NETs）是中性粒细胞的主要防御机制之一。在这项研究中，我们观察到，与怀孕奶牛相比，在人工授精 (AI) 后第 16-18 天，血液中性粒细胞在非授精和授精的非妊娠母牛中产生更高 (p < 0.01) 的离体NET。体外研究还表明，IFNτ 以剂量和时间依赖性方式阻碍 NETs 的形成。当中性粒细胞与 9 ng/mL IFNτ 孵育 3.5 小时时，观察到 IFNτ 刺激基因（ISG15、OAS1、MX1）的最低 (p < 0.01) NETs 形成和最高 (p < 0.01) mRNA 表达 (RT-PCR)。使用 JAK2、JAK3、p38、PI3K/Akt 和 MAPK/Erk 的抑制剂鉴定了介导 NETs 形成的 IFNτ 损伤的信号级联。IFNτ 降低（p < 0.01）介导血液中性粒细胞中 NET 形成的基因和蛋白质的 mRNA 表达 (RT-PCR) 和浓度 (ELISA)，包括组蛋白 (H1、H2)、中性粒细胞弹性蛋白酶 (NE) 和髓过氧化物酶 (MPO)。然而，在 JAK3 或 PI3K 抑制剂存在的情况下，IFNτ 对这些基因和蛋白质的影响被消除。免疫细胞化学研究还表明，与阳性对照（PC、单独的 IFNτ）相比，在 JAK3 或 PI3K 抑制剂存在的情况下，MPO 信号很强。结果表明 IFNτ 使用 JAK3 和 PI3K 削弱 NETs 的形成，因此对奶牛成功植入和建立妊娠至关重要。