title: Innate immune response in experimentally induced bovine intramammary infection with Staphylococcus simulans and S. epidermidis.
abstract: Coagulase-negative staphylococci (CNS) are in several countries the most common bacteria isolated in subclinical mastitis. To investigate the innate immune response of cows to infections with two common mastitis-causing CNS species, Staphylococcus epidermidis and Staphylococcus simulans, experimental intramammary infection was induced in eight cows using a crossover design. The milk somatic cell count (SCC), N-acetyl-β-D-glucosaminidase (NAGase) activity, milk amyloid A (MAA), serum amyloid A (SAA) and proinflammatory cytokines interleukin (IL)-1β, IL-8, and tumor necrosis factor α (TNF-α) were determined at several time points before and after challenge. All cows became infected and showed mild to moderate clinical signs of mastitis. The spontaneous elimination rate of the 16 infections was 31.3%, with no difference between species. Infections triggered a local cytokine response in the experimental udder quarters, but cytokines were not detected in the uninfected control quarters or in systemic circulation. The innate local immune response for S. simulans was slightly stronger, with significantly higher concentrations of IL-1β and IL-8. The IL-8 response could be divided into early, delayed, or combined types of response. The CNS species or persistency of infection was not associated with the type of IL-8 response. No significant differences were seen between spontaneously eliminated or persistent infections.
authors.affiliation: University of Helsinki, Faculty of Veterinary Medicine, Department of Production Animal Medicine, Paroninkuja 20, FI-04920 Saarentaus, Finland. heli.simojoki@helsinki.fi.
authors.forename: Heli
authors.initials: H
authors.lastname: Simojoki
authors.forename: Tiina
authors.initials: T
authors.lastname: Salomäki
authors.forename: Suvi
authors.initials: S
authors.lastname: Taponen
authors.forename: Antti
authors.initials: A
authors.lastname: Iivanainen
authors.forename: Satu
authors.initials: S
authors.lastname: Pyörälä
mesh_terms: D000118:Acetylglucosaminidase / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D015169:Colony Count, Microbial / Q000662:veterinary; D018592:Cross-Over Studies; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007113:Immunity, Innate; D008321:Mammary Glands, Animal / Q000276:immunology* / Q000382:microbiology; D008414:Mastitis, Bovine / Q000276:immunology* / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D000685:Serum Amyloid A Protein / Q000378:metabolism; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D013210:Staphylococcus / Q000302:isolation & purification / Q000502:physiology*; D013212:Staphylococcus epidermidis / Q000302:isolation & purification / Q000502:physiology
chemical_list: D016207:Cytokines; D000685:Serum Amyloid A Protein; D000118:Acetylglucosaminidase