title: Escherichia coli- and Staphylococcus aureus-induced mastitis differentially modulate transcriptional responses in neighbouring uninfected bovine mammary gland quarters.
abstract: BACKGROUND
  The most important disease of dairy cattle is mastitis, caused by the infection of the mammary gland by various micro-organisms. Although the transcriptional response of bovine mammary gland cells to in vitro infection has been studied, the interplay and consequences of these responses in the in vivo environment of the mammary gland are less clear. Previously mammary gland quarters were considered to be unaffected by events occurring in neighbouring quarters. More recently infection of individual quarters with mastitis causing pathogens, especially Escherichia coli, has been shown to influence the physiology of neighbouring uninfected quarters. Therefore, the transcriptional responses of uninfected mammary gland quarters adjacent to quarters infected with two major mastitis causing pathogens, E. coli and Staphylococcus aureus, were compared.
  
  
  RESULTS
  The bacteriologically sterile, within-animal control quarters exhibited a transcriptional response to the infection of neighbouring quarters. The greatest response was associated with E. coli infection, while a weaker, yet significant, response occurred during S. aureus infection. The transcriptional responses of these uninfected quarters included the enhanced expression of many genes previously associated with mammary gland infections. Comparison of the transcriptional response of uninfected quarters to S. aureus and E. coli infection identified 187 differentially expressed genes, which were particularly associated with cellular responses, e.g. response to stress. The most affected network identified by Ingenuity Pathway analysis has the immunosuppressor transforming growth factor beta 1 (TGFB1) at its hub and largely consists of genes more highly expressed in control quarters from S. aureus infected cows.
  
  
  CONCLUSIONS
  Uninfected mammary gland quarters reacted to the infection of neighbouring quarters and the responses were dependent on pathogen type. Therefore, bovine udder quarters exhibit interdependence and should not be considered as separate functional entities. This suggests that mastitis pathogens not only interact directly with host mammary cells, but also influence discrete sites some distance away, which will affect their response to the subsequent spread of the infection. Understanding the underlying mechanisms may provide further clues for ways to control mammary gland infections. These results also have implications for the design of experimental studies investigating immune regulatory mechanisms in the bovine mammary gland.
authors: Division of Infection & Immunity, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK. kirsty.jensen@roslin.ed.ac.uk
authors: Kirsty
authors: K
authors: Jensen
authors: Juliane
authors: J
authors: Günther
authors: Richard
authors: R
authors: Talbot
authors: Wolfram
authors: W
authors: Petzl
authors: Holm
authors: H
authors: Zerbe
authors: Hans-Joachim
authors: HJ
authors: Schuberth
authors: Hans-Martin
authors: HM
authors: Seyfert
authors: Elizabeth J
authors: EJ
authors: Glass
mesh_terms: D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000502:physiology*; D004927:Escherichia coli Infections / Q000235:genetics / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D008414:Mastitis, Bovine / Q000235:genetics* / Q000382:microbiology* / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D013203:Staphylococcal Infections / Q000235:genetics / Q000473:pathology; D013211:Staphylococcus aureus / Q000502:physiology*; D013997:Time Factors; D014158:Transcription, Genetic