硒调控ROS介导的NLRP3/焦亡信号通路对奶牛乳腺上皮细胞炎性损伤的保护机制研究

Staphylococcus aureus (S. aureus) is one of the main pathogen that induced bovine mastitis, but the mechanism of infection by this pathogen is still unclear. It has been gradually found that NLRP3/pyroptosis signaling pathway mediated by Reactive Oxygen Species (ROS) is closely related with inflammation. Our previous study found that selenium can degrade ROS and alleviate the inflammatory injury of bMECs induced by S. aureus. So we ask whether selenium can regulate ROS-mediated NLRP3/pyroptosis signaling pathway to achieve anti-inflammatory effect. Based on these hypothesis, First in vitro model will be performed and NLRP3 will be blocked by MCC950 in this project to study the mechanisms of NLRP3/pyroptosis signaling pathway in regulating the inflammatory injury of bMECs induced by S. aureus; Then selenium will be added and ROS will be scavenged to study the effect of selenium on NLRP3/pyroptosis signaling pathway; Finally in vivo model will be performed by using SD rats to study the effect of selenium on NLRP3/pyroptosis signaling pathway in breast tissue; According to above results, systematically explains the protection mechanism of selenium on inflammatory injury of bMECs by regulating ROS-mediated NLRP3/pyroptosis signaling pathway. This project will contribute to a better understanding of mastitis induced by S. aureus, but also to provide theoretic foundation for anti-inflammatory mechanisms and rational application of selenium.

金黄色葡萄球菌（金葡菌）是奶牛乳腺炎的主要致病菌之一，其感染机制尚不完全清楚。已经证实活性氧（ROS）可介导NLRP3/焦亡信号通路活化，调控炎症反应。前期结果表明，硒可降解胞内ROS缓解金葡菌诱导的奶牛乳腺上皮细胞（bMECs）炎性损伤。那么，硒的抗炎效果能否通过该通路实现，有待于进一步研究。因此，本项目首先建立金葡菌感染bMECs体外模型，利用MCC950抑制NLRP3的表达，研究NLRP3/焦亡信号通路对bMECs炎性损伤的调控机制；然后，添加硒干预，利用NAC清除ROS，研究硒对NLRP3/焦亡信号通路的影响；最后，建立金葡菌感染大鼠乳腺体内模型，研究硒对乳腺NLRP3/焦亡信号通路的调控机制。综合以上结果，系统阐述硒调控ROS介导的NLRP3/焦亡信号通路对bMECs炎性损伤的保护机制。本项目是对金葡菌性乳腺炎研究的进一步深入，同时为硒的抗炎机制和合理应用提供理论依据。

奶牛乳房炎是奶牛养殖业中常见疾病之一。金黄色葡萄球菌(金葡菌)是引起奶牛乳房炎最常见的病原菌之一，硒是奶牛养殖过程中重要的饲源性微量元素，可通过调控多条信号通路的方式参与炎症和免疫调节等生物学过程。然而硒能否通过 NLRP3/焦亡途径调控金黄色葡萄球菌诱导的奶牛乳腺上皮细胞炎性损伤，有待于进一步研究。 因此本研究聚焦于硒对金葡菌感染的乳腺NLRP3/焦亡信号通路的影响。研究发现：在个体水平上妊娠期补硒可有效提高动物体的抗氧化水平，增加硒在乳腺、肝脏等器官内的沉积率，并可抑制NLRP3/焦亡通路关键蛋白的表达降低金葡菌诱导的乳腺组织炎性损伤；在细胞水平上硒可下调金葡菌诱导的乳腺上皮细胞ROS的活性，调控NLRP3/焦亡信号通路改善金葡菌诱导的细胞炎性损伤。本研究证明：硒可抑制NLRP3/焦亡信号通路的转导改善金葡菌诱导的乳腺炎性损伤。本项目可为金葡菌性乳腺炎防控体系的构建提供数据支撑，为硒的应用提供理论依据。