title: The immune response of bovine mammary epithelial cells to live or heat-inactivated Mycoplasma bovis.
abstract: Mycoplasma bovis is an emerging bacterial agent causing bovine mastitis. Although these cell wall-free bacteria lack classical virulence factors, they are able to activate the immune system of the host. However, effects on the bovine mammary immune system are not yet well characterized and detailed knowledge would improve the prevention and therapy of mycoplasmal mastitis. The aim of this study was to investigate the immunogenic effects of M. bovis on the mammary gland in an established primary bovine mammary epithelial cell (bMEC) culture system. Primary bMEC of four different cows were challenged with live and heat-inactivated M. bovis strain JF4278 isolated from acute bovine mastitis, as well as with the type strain PG45. The immune response was evaluated 6 and 24h after mycoplasmal challenge by measuring the relative mRNA expression of selected immune factors by quantitative PCR. M. bovis triggered an immune response in bMEC, reflected by the upregulation of tumor necrosis factor-α, interleukin(IL)-1β, IL-6, IL-8, lactoferrin, Toll-like receptor-2, RANTES, and serum amyloid A mRNA. Interestingly, this cellular reaction was only observed in response to live, but not to heat-inactivated M. bovis, in contrast to other bacterial pathogens of mastitis such as Staphylococcus aureus. This study provides evidence that bMEC exhibit a strong inflammatory reaction in response to live M. bovis. The lack of a cellular response to heat-inactivated M. bovis supports the current hypothesis that mycoplasmas activate the immune system through secreted secondary metabolites.
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty University of Bern, Experimental station, Route de la Tioleyre 4, 1725 Posieux, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Freiestrasse 1, 3012 Bern, Switzerland.
authors.forename: Christina
authors.initials: C
authors.lastname: Zbinden
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland.
authors.forename: Paola
authors.initials: P
authors.lastname: Pilo
authors.affiliation: Institute of Veterinary Bacteriology, Vetsuisse Faculty University of Bern, Länggassstrasse 122, 3012 Bern, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Frey
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty University of Bern, Experimental station, Route de la Tioleyre 4, 1725 Posieux, Switzerland.
authors.forename: Rupert M
authors.initials: RM
authors.lastname: Bruckmaier
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty University of Bern, Experimental station, Route de la Tioleyre 4, 1725 Posieux, Switzerland. Electronic address: olga.wellnitz@vetsuisse.unibe.ch.
authors.forename: Olga
authors.initials: O
authors.lastname: Wellnitz
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D006358:Hot Temperature; D008321:Mammary Glands, Animal / Q000166:cytology*; D045682:Mycoplasma bovis / Q000502:physiology*
chemical_list: D016207:Cytokines
keywords: Bovine mammary epithelial cells; Innate immune response; Mastitis; Mycoplasma bovis