Variant innate immune responses of mammary epithelial cells to challenge by Staphylococcus aureus, Escherichia coli and the regulating effect of taurine on these bioprocesses.
Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are important pathogens causing subclinical and clinical bovine mastitis, respectively. Taurine, an organic acid found in animal tissues, has been used for the treatment of various superficial infections and chronic inflammations. We challenged a bovine mammary epithelial cell (MEC) line (MAC-T) or a mouse mammary epithelial cell line (EpH4-Ev) with either E. coli or S. aureus and compared the responses of MECs to these 2 pathogens. We also examined the regulatory effects of taurine on these responses. Receptor analyses showed that both TLR2 and TLR4 are upregulated upon exposure to either E. coli or S. aureus. Taurine pre-treatment dampened upregulation to some extent. E. coli and S. aureus stimulated comparable levels of ROS, which could be inhibited by taurine pre-treatment. E. coli infection elicited a dramatic change in iNOS expression. Taurine significantly decreased iNOS expression in the S. aureus challenged group. Protein microarray demonstrated that 32/40 and 8/40 inflammatory molecules/mediators were increased after E. coli or S. aureus challenge, respectively. The fold changes of most molecules were higher in the E. coli infection group than that in the S. aureus infection group. Taurine negatively regulated the inflammatory profile in both bacterial infections. Pro-inflammatory cytokines (such as TNF-α) connected with TLR activation were down-regulated by taurine pre-treatment. The influence of TAK-242 and OxPAPC on cytokine/molecule expression profiles to E. coli challenge are different than to S. aureus. Some important factors (MyD88, TNF-α, IL-1β, iNOS and IL-6) mediated by TLR activation were suppressed either in protein microarray or special assay (PCR/kits) or both. TAK-242 restrained ROS production and NAGase activity similar to the effect of taurine in E. coli challenge groups. The detection of 3 indices (T-AOC, SOD and MDA) reflecting oxidative stress in vivo, showed that taurine improved the antioxidant ability of cells. We conclude that taurine can regulate the inflammatory response during infection with E. coli and prevent cell damage by affecting the signaling pathways mediated by TLRs and by improving the antioxidant ability of cells. In S. aureus infections, taurine's antioxidant ability may be the primary means of resistance to inflammation. This study provides a better understanding of the inflammatory mechanisms of E. coli and S. aureus mastitis, and it provides a putative strategy for the prevention of this disease.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Liuhai
L
Zheng
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Yuanyuan
Y
Xu
Jiangsu Agri-animal Husbandry Vocational College, Taizhou 225300, China.
Jinye
J
Lu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Ming
M
Liu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Bin Dai
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: mjf171647@126.com.
Jinfeng
J
Miao
Chinese Academy of Science, Institute of Subtropical Agriculture, Research Center for Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center for Animal & Poultry Science, Key Laboratory of Agroecology in Subtropical Region, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central China, Ministry of Agriculture, Changsha 410125, China.
Yulong
Y
Yin
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002417:Cattle; D004847:Epithelial Cells / Q000187:drug effects / Q000382:microbiology; D004926:Escherichia coli / Q000187:drug effects / Q000472:pathogenicity; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects* / Q000276:immunology; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity; D013654:Taurine / Q000008:administration & dosage*; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism
D000975:Antioxidants; D017382:Reactive Oxygen Species; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D013654:Taurine; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse
Escherichia coli; Mastitis; ROS; Staphylococcus aureus; Taurine