Lactobacillus casei possesses many kinds of bioactivities, such as anti-inflammation and anti-oxidant, and has been applied to treating multiple inflammatory diseases. However, its role in mastitis prevention has remained ambiguous. This study aimed to examine the mechanisms underlying the preventive effects of L. casei 03 against E. coli- mastitis utilizing bovine mammary epithelial cells (BMECs) and a mouse model. In vitro assays revealed pretreatment with L. casei 03 reduced the apoptotic ratio and the mRNA expression levels of IL1β, IL6 and TNFα and suppressed phosphorylation of p65, IκBα, p38, JNK and ERK in the NF-κB signaling pathway and MAPK signaling pathway. Furthermore, in vivo tests indicated that intramammary infusion of L. casei 03 relieved pathological changes, reduced the secretion of IL1β, IL6 and TNFα and MPO activity in the mouse mastitis model. These data suggest that L. casei 03 exerts protective effects against E. coli-induced mastitis in vitro and in vivo and may hold promise as a novel agent for the prevention and treatment of mastitis.

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干酪乳杆菌03对大肠杆菌引起的乳腺炎的体内外预防作用

干酪乳杆菌具有抗炎、抗氧化等多种生物活性，已被应用于治疗多种炎症性疾病。然而，它在预防乳腺炎中的作用仍然不明确。本研究旨在利用牛乳腺上皮细胞 (BMEC) 和小鼠模型来研究干酪乳杆菌 03 对大肠杆菌乳腺炎的预防作用的机制。体外实验显示，L. casei 03 预处理可降低细胞凋亡率以及 IL1β、IL6 和 TNFα 的 mRNA 表达水平，并抑制 NF-κB 信号通路和 MAPK 信号通路中 p65、IκBα、p38、JNK 和 ERK 的磷酸化。此外，体内试验表明，乳房内输注干酪乳杆菌03可缓解小鼠乳腺炎模型的病理变化，减少IL1β、IL6和TNFα的分泌以及MPO活性。这些数据表明干酪乳杆菌03在体外和体内对大肠杆菌诱导的乳腺炎发挥保护作用，并有望成为预防和治疗乳腺炎的新型药物。