Roles Of MCPIP1 In The Process Of Inflammatory Responses And Oxidative Damage Induced By Lipopolysaccharide And Lipoteichoic Acid In Bovine Mammary Epithelial Cells

Bovine mastitis is a comprehensive disease caused by physiological factors of the bovine or the stimulation of the external conditional pathogenic microorganisms.It could cause the most economic loss in the dairy farming industry.Bovine mastitis severely affects the quality and quantity of milk and leads to impaired or even complete loss of lactation.The two common pathogens in bovine mastitis are Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).Lipopolysaccharide(LPS)is an important component of E.coli cell wall that can induce inflammatory responses.Lipoteichoic acid(LTA)is present on the cell wall of S.aureus and causes a variety of immune responses of the host.Monocyte chemoattractant protein-induced protein 1(MCPIP1)acts as a transcription factor and plays an irreplaceable role in the autoimmune response and inflammatory processes.However,whether MCPIP1 is involved in LPS and LTA-induced immune response in mammary gland epithelial cells has not been demonstrated.In this experiment,real-time quantitative PCR(RT-qPCR)and Western blotting experiments showed that the expression of MCPIP1 in inflammatory mammary gland tissues was significantly higher than that in normal bovine mammary tissues.We first used the immortalized bovine mammary alveolar cell-T(MAC-T)cells as pattern recognition receptors and stimulated them with LPS or LTA to establish an inflammatory cell model.It was found that MCPIP1 mRNA level and protein level were higher in inflammatory MAC-T cells than those in normal cells,consistent with expression in mammary tissue.The above indicates that MCPIP1 is involved in the inflammatory process of bovine mammary epithelial cells.In order to further study how MCPIP1 plays a role in LPS and LTA-induced immune responses in bovine mammary epithelial cells,MAC-T cell clones stably overexpressing MCPIP1 were established by introducing the lentiviral vector containing MCPIP1 sequence to further study the biological characteristics of MCPIP1 on cellular inflammatory factor secretion,cell proliferation,apoptosis,DNA damage and oxidative damage in the inflammatory response of MAC-T cells.We found that overexpression of MCPIP1 inhibited LPS-and LTA-induced expressions of inflammatory mediators TNF-α、IL-1β 、 IL-6 and IL-8 in epithelial cells;MCPIP1 enhanced LPS-and LTA-induced proliferation inhibition,oxidative damage,and DNA damage in mammary epithelial cells.In conclusion,MCPIP1 mediates oxidative damages and inflammatory responsesinduced by LPS and LTA in bovine mammary epithelial cells,and this study provides a new way of thinking to study the pathological mechanism of bovine mastitis.