LncRNA-XIST Mediates Bovine Mammary Epithelial Cell Inflammatory Response Via NF-κB/NLRP3 Inflammasome Pathway

As an important part of animal husbandry in China,the dairy industry is closely related to national economy and people’s livelihood,while mastitis is one of the main diseases that directly affect the long-term stable and rapid development of dairy industry.The harm of bovine mastitis urges scholars all over the world to research this disease from multiple perspectives of pathogenesis,diagnosis,treatment and prevention and studies about this disease have covered multiple molecular levels,including DNA,m RNA,microRNA and protein,but the pathogenesis is not completely clear.Nowadays,the correlation between long noncoding RNAs(lncRNAs)X-inactive specific transcript(XIST)and diverse diseases of mammals has been proved by many researches.However,the recognization about XIST in bovine mastitis remains limited.The present study based on long noncoding RNAs(lncRNAs)XIST,attempting to find XIST were significantly related to bovine mastitis and figure out the relevant mechanisms.In this study,bovine mastitic tissues and inflammatory bovine mammary alveolar cell-T(MAC-T)cell line were used as objects of study.MAC-T cells were triggered by Escherichia coli(E.coli)or Staphylococcus aureus(S.aureus)to build inflammatory models.The proliferation ability,migration capacity,viability,and apoptosis level of MAC-T cell under inflammatory conditions were measured and relevant mechanism was detected.The results found that lncRNA XIST was abnormally increased in bovine mastitic tissues and inflammatory bovine mammary alveolar cell-T(MAC-T)cell line which was triggered by E.coli or S.aureus.Silencing of XIST significantly reduced the expression of E.coli or S.aureus-induced the production of pro-inflammatory factors,including tumor necrosis factor(TNF)-α,interleukin(IL)-1β and IL-6.In addition,XIST knockdown could obviously inhibit cell proliferation,viability and migration,and significantly promote cell apoptosis under inflammatory conditions.The present study revealed XIST inhibited E.coli or S.aureus-induced NF-κB phosphorylation,as well as the activation of NOD-like receptor protein 3(NLRP3)inflammasome.Finally,the production of NLRP3 inflammasome and the transcription of XIST triggered by E.coli or S.aureus were both the consequences of the activation of NF-κB signaling pathway.In conclusion,the expression of XIST was promoted by the activated NF-κB pathway,and in turn,XIST generated a negative feedback loop to regulate the NF-κB/NLRP3 inflammasome pathway for mediating the process of inflammation.Understanding the key role of lncRNA XIST in bovine mammary epithelial cells under inflammatory conditions will contribute to the identification of new therapeutic targets for treating bovine mastitis.