title: Escherichia coli, but not Staphylococcus aureus triggers an early increased expression of factors contributing to the innate immune defense in the udder of the cow.
abstract: The outcome of an udder infection is influenced by the pathogen species. We established a strictly defined infection model to better analyze the unknown molecular causes for these pathogen-specific effects, using Escherichia coli and Staphylococcus aureus strains previously asseverated from field cases of mastitis. Inoculation of quarters with 500 CFU of E. coli (n = 4) was performed 6 h, 12 h, and 24 h before culling. All animals showed signs of acute clinical mastitis 12 h after challenge: increased somatic cell count (SCC), decreased milk yield, leukopenia, fever, and udder swelling. Animals inoculated with 10 000 CFU of S. aureus for 24 h (n = 4) showed no or only modest clinical signs of mastitis. However, S. aureus caused clinical signs in animals, inoculated for 72 h-84 h. Real-time PCR proved that E. coli inoculation strongly and significantly upregulated the expression of beta-defensins, TLR2 and TLR4 in the pathogen inoculated udder quarters as well as in mammary lymph nodes. TLR3 and TLR6 were not significantly regulated by the infections. Immuno-histochemistry identified mammary epithelial cells as sites for the upregulated TLR2 and beta-defensin expression. S. aureus, in contrast, did not significantly regulate the expression of any of these genes during the first 24 h after pathogen inoculation. Only 84 h after inoculation, the expression of beta-defensins, but not of TLRs was significantly (> 20 fold) upregulated in five out of six pathogen inoculated quarters. Using the established mastitis model, the data clearly demonstrate a pathogen-dependent difference in the time kinetics of induced pathogen receptors and defense molecules.
authors.affiliation: Clinic for Ruminants, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Petzl
authors.forename: Holm
authors.initials: H
authors.lastname: Zerbe
authors.forename: Juliane
authors.initials: J
authors.lastname: Günther
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Seyfert
authors.forename: Gerd
authors.initials: G
authors.lastname: Nürnberg
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Schuberth
mesh_terms: D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000502:physiology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D007113:Immunity, Innate / Q000502:physiology*; D007155:Immunologic Factors / Q000378:metabolism*; D008198:Lymph Nodes / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000276:immunology*; D008414:Mastitis, Bovine / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D008892:Milk / Q000166:cytology / Q000382:microbiology; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary; D013211:Staphylococcus aureus / Q000502:physiology*; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D023083:beta-Defensins / Q000378:metabolism
chemical_list: D007155:Immunologic Factors; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D023083:beta-Defensins