title: Staphylococcus aureus and Escherichia coli elicit different innate immune responses from bovine mammary epithelial cells.
abstract: Escherichia coli and Staphylococcus aureus are the most important pathogenic bacteria causing bovine clinical mastitis and subclinical mastitis, respectively. However, little is known about the molecular mechanisms underlying the different host response patterns caused by these bacteria. The aim of this study was to characterize the different innate immune responses of bovine mammary epithelium cells (MECs) to heat-inactivated E. coli and S. aureus. Gene expression of Toll-like receptor 2 (TLR2) and TLR4 was compared. The activation of nuclear factor kappa B (NF-κB) and the kinetics and levels of cytokine production were analyzed. The results show that the mRNA for TLR2 and TLR4 was up-regulated when the bovine MECs were stimulated with heat-inactivated E. coli, while only TLR2 mRNA was up-regulated when the bovine MECs were stimulated with heat-inactivated S. aureus. The expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and IL-8 increased more rapidly and higher when the bovine MECs were stimulated with heat-inactivated E. coli than when they were stimulated with heat-inactivated S. aureus. E. coli strongly activated NF-κB in the bovine MECs, while S. aureus failed to activate NF-κB. Heat-inactivated S. aureus could induce NF-κB activation when bovine MECs cultured in medium without fetal calf serum. These results were confirmed using TLR2- and TLR4/MD2-transfected HEK293 cells and suggested that differential TLR recognition and the lack of NF-κB activation account for the impaired immune response elicited by heat-inactivated S. aureus.
authors.affiliation: Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun, Jilin Province 130062, People's Republic of China.
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Fu
authors.forename: Ershun
authors.initials: E
authors.lastname: Zhou
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Fenyang
authors.initials: F
authors.lastname: Li
authors.forename: Dejie
authors.initials: D
authors.lastname: Liang
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Song
authors.forename: Fuyi
authors.initials: F
authors.lastname: Zhao
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: Fen
authors.forename: Depeng
authors.initials: D
authors.lastname: Li
authors.forename: Yongguo
authors.initials: Y
authors.lastname: Cao
authors.forename: Xichen
authors.initials: X
authors.lastname: Zhang
authors.forename: Naisheng
authors.initials: N
authors.lastname: Zhang
authors.forename: Zhengtao
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000818:Animals; D002417:Cattle; D004847:Epithelial Cells; D004926:Escherichia coli / Q000276:immunology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000662:veterinary*; D005260:Female; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology*; D008414:Mastitis, Bovine / Q000276:immunology / Q000382:microbiology*; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013203:Staphylococcal Infections / Q000276:immunology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000235:genetics / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology
chemical_list: D016328:NF-kappa B; D012333:RNA, Messenger; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4
keywords: Bovine mammary epithelial cells; Escherichia coli; NF-κB; Staphylococcus aureus; TLR2; TLR4