title: Purified Staphylococcus aureus leukotoxin LukM/F' does not trigger inflammation in the bovine mammary gland.
abstract: An early recruitment of neutrophils in mammary tissue and milk is considered an important component of the defense of the mammary gland against Staphylococcus aureus. We investigated whether the leukotoxin LukM/F', which is produced by a proportion of mastitis-causing strains of S. aureus, would be able to trigger inflammation in the udder. Infusion of purified LukM/F' toxin in lactating mammary glands did not cause neutrophil influx in milk, showing that the toxin was not able to cause mastitis on its own. Purified LukM/F' did not kill or stimulate mammary epithelial cells in culture. As expected, LukM bound to mammary macrophages and the complete LukM/F' toxin killed these cells, but subcytotoxic LukM/F' concentrations did not induce secretion of IL-8, TNF-α, IL-1β or IL-6 by macrophages. On the contrary, the production of these pro-inflammatory mediators by adhesion-stimulated macrophages was reduced. Overall, these results indicate that purified leukotoxin LukM/F' is not likely to contribute to the initiation of the inflammatory response and could even play an anti-inflammatory role in the mammary gland by inactivating macrophages.
authors.affiliation: INRA, UR 1282 Infectiologie Animale et Santé Publique, IASP Bat. 311, F-37380 Nouzilly, France.
authors.forename: Angélina
authors.initials: A
authors.lastname: Fromageau
authors.forename: Patricia
authors.initials: P
authors.lastname: Cunha
authors.forename: Florence B
authors.initials: FB
authors.lastname: Gilbert
authors.forename: Pascal
authors.initials: P
authors.lastname: Rainard
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002417:Cattle; D002470:Cell Survival; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology; D005260:Female; D007249:Inflammation / Q000382:microbiology / Q000473:pathology; D007956:Leukocidins / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects / Q000502:physiology; D008321:Mammary Glands, Animal / Q000382:microbiology* / Q000473:pathology*; D009504:Neutrophils / Q000276:immunology; D013211:Staphylococcus aureus / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D016207:Cytokines; D007956:Leukocidins; C091659:LukM protein, Staphylococcus aureus; D037521:Virulence Factors; C074300:LukF protein, Staphylococcus aureus