Cows are susceptible to pathogenic bacterial infection after pregnancy, leading to inflammation of the endometrium. Aucubin (AU) has been proven to exhibit highly effective anti-inflammatory activity, but its ability to protect against endometritis in dairy cows remains unclear. Therefore, the goal of the present study was to evaluate the protective effect of AU on the LPS-induced inflammatory response of bovine endometrial epithelial cells (BEECs). After pre-treating BEECs with AU (10, 20 and 50 μM) for 6 hr, the cells were stimulated with LPS for 3 hr. Subsequently, BEECs apoptosis was analysed by flow cytometry, the expression of pro-inflammatory cytokine mRNA was detected by qRT-PCR, and changes in NF-κB and Keap1/Nrf2 signalling were analysed by western blotting and immunofluorescence analyses. The results showed that AU can reduce TNF-α, IL-1β, IL-6, COX-2 and iNOS mRNA expression in BEECs and reduce cell apoptosis. Furthermore, AU significantly reduced the level of NF-κB p65 and IκB phosphorylation and inhibited the nuclear translocation of NF-κB p65. AU also activated the Keap1/Nrf2 pathway, promoting the nuclear transfer of Nrf2 and increasing Keap1, Nrf2, HO-1 and NQO1 mRNA and protein levels. Taken together, these results indicate that AU ameliorates the LPS-induced inflammatory response by inhibiting NF-κB and activating the Keap1/Nrf2 signalling pathway, which has a protective effect on BEECs.

中文翻译：

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Aucubin 通过抑制 NF-κB 和激活 Keap1/Nrf2 信号通路改善 LPS 诱导的牛子宫内膜上皮细胞炎症反应

奶牛怀孕后易感染病原菌，导致子宫内膜发炎。Aucubin (AU) 已被证明具有高效的抗炎活性，但其预防奶牛子宫内膜炎的能力仍不清楚。因此，本研究的目的是评估 AU 对 LPS 诱导的牛子宫内膜上皮细胞 (BEEC) 炎症反应的保护作用。用 AU（10、20 和 50 μM）预处理 BEEC 6 小时后，用 LPS 刺激细胞 3 小时。随后，通过流式细胞术分析 BEECs 细胞凋亡，通过 qRT-PCR 检测促炎细胞因子 mRNA 的表达，并通过蛋白质印迹和免疫荧光分析分析 NF-κB 和 Keap1/Nrf2 信号传导的变化。结果表明AU可以降低TNF-α，IL-1β、IL-6、COX-2 和 iNOS mRNA 在 BEEC 中的表达并减少细胞凋亡。此外，AU 显着降低了 NF-κB p65 和 IκB 磷酸化的水平，并抑制了 NF-κB p65 的核易位。AU 还激活了 Keap1/Nrf2 通路，促进了 Nrf2 的核转移并增加了 Keap1、Nrf2、HO-1 和 NQO1 mRNA 和蛋白质水平。总之，这些结果表明 AU 通过抑制 NF-κB 和激活 Keap1/Nrf2 信号通路来改善 LPS 诱导的炎症反应，这对 BEEC 具有保护作用。促进 Nrf2 的核转移并增加 Keap1、Nrf2、HO-1 和 NQO1 mRNA 和蛋白质水平。总之，这些结果表明 AU 通过抑制 NF-κB 和激活 Keap1/Nrf2 信号通路来改善 LPS 诱导的炎症反应，这对 BEEC 具有保护作用。促进 Nrf2 的核转移并增加 Keap1、Nrf2、HO-1 和 NQO1 mRNA 和蛋白质水平。总之，这些结果表明 AU 通过抑制 NF-κB 和激活 Keap1/Nrf2 信号通路来改善 LPS 诱导的炎症反应，这对 BEEC 具有保护作用。