Escherichia coli induces apoptosis and proliferation of mammary cells

Mammary cell apoptosis and proliferation were assessed after injection of Escherichia coli into the left mammary quarters of six cows. Bacteriological analysis of foremilk samples revealed coliform infection in the injected quarters of four cows. Milk somatic cell counts increased in these quarters and peaked at 24 h after bacterial injection. Body temperature also increased, peaking at 12 h postinjection, The number of apoptotic cells was significantly higher in the mastitic tissue than in the uninfected control. Expression of Bax and interleukin-1 beta converting enzyme increased in the mastitic tissue at 24 h and 72 h postinfection, whereas Bcl-2 expression decreased at 24 h but did not differ significantly from the control at 72 h postinfection, Induction of matrix metalloproteinase-g, stromelysin-1 and urokinase-type plasminogen activator was also observed in the mastitic tissue. Moreover, cell proliferation increased in the infected tissue, These results demonstrate that Escherichia coli-induced mastitis promotes apoptosis and cell proliferation

Production d'anticorps monoclonaux et polyclonaux diriges contre les pepsines bovine et porcine . Etude de l'influence des conditions du milieu sur leur antigenicite, application a leur detection dans les fromages

*INRA Station Experimentale Laitiere BP 89 Poligny 39801 (FRA) Diffusion du document : INRA Station Experimentale Laitiere BP 89 Poligny 39801 (FRA) Diplôme : Dr. Ing

Detection of residual chymosin in cheese by an enzyme-linked immunosorbent assay

International audienc

Monoclonal antibodies as probes for the changes in antigenicity of bovine and porcine aspartyl proteases with pH

International audienc

In vivo imaging of NF-kappa B activity during Escherichia coli-induced mammary gland infection

In mammary gland infections, the contribution of NF-kappa B is not well defined, and was therefore investigated following intramammary inoculation of Escherichia coli. Non-invasive real-time in vivo imaging of the transcription factor activation was performed in mammary glands of transgenic mice expressing luciferase under the control of NF-kappa B. Bacterial inoculation resulted in a major increase in luminescence as compared with control glands. This activation was confirmed by immunohistochemical nuclear staining of the NF-kappa B p65 subunit in mammary epithelium of infected glands, while nuclear p50 was not detected. The systemic response to the intramammary inoculation of Escherichia coli was also studied. NF-kappa B activation in the liver increased over time, and a relatively mild but longer-lasting response was observed as compared with the acute hepatic response of mice receiving lipopolysaccharide. This systemic reaction was confirmed by increased circulating levels of the acute phase protein serum amyloid A, tumour necrosis factor-alpha and interleukin-6. In addition, high concentrations of both cytokines in the mammary gland inoculated with bacteria showed that the infection was also well established at the local level. These results indicate that in vivo monitoring of NF-kappa B activation is an attractive novel approach to study mammary gland inflammation, and that this transcription factor is imperative in the early stages of the host immune response towards coliform intramammary infections, both at the local and systemic level