title: A novel conditional platelet depletion mouse model reveals the importance of platelets in protection against Staphylococcus aureus bacteremia.
abstract: BACKGROUND
  Platelets are critical cells for maintaining vascular hemostasis, but their activities in other processes are becoming apparent. Specifically, the ability of platelets to recognize and respond to infectious agents is an important area of investigation. To understand the physiologic roles of platelets in vivo, most researchers have used antibody-mediated platelet depletion, which has certain limitations.
  
  
  OBJECTIVE
  To develop an optimal system with which to study the contribution of platelets to protection against S. aureus blood infection.
  
  
  METHODS
  Here, we describe a novel experimental model of conditional platelet depletion based on the Cre-recombinase cell ablation system. With this technology, the simian diphtheria toxin receptor was expressed in platelet factor 4-positive cells (megakaryocytes and platelets).
  
  
  RESULTS
  Systemic administration of diphtheria toxin every 48 h resulted in reduced platelet numbers that became undetectable after 6 days. Although platelets were depleted, no other blood cells were affected. With this newly developed model, the functional contributions of platelets to protection against Staphylococcus aureus bacteremia was examined. Platelet-depleted mice succumbed to infection more rapidly than wild-type mice, and had a significantly higher bacterial burden in kidneys, elevated levels of serum markers of kidney damage, and increased levels of cytokines indicative of septic shock.
  
  
  CONCLUSIONS
  Here, we illustrate a new mouse model for conditional platelet depletion, and implicate platelets as important participants in the immune response to bacterial blood infections.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Wuescher
authors.forename: A
authors.initials: A
authors.lastname: Takashima
authors.forename: R G
authors.initials: RG
authors.lastname: Worth
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D058491:Bacterial Load; D001792:Blood Platelets / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D016207:Cytokines / Q000097:blood; D004167:Diphtheria Toxin / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D066257:Heparin-binding EGF-like Growth Factor / Q000819:agonists / Q000097:blood* / Q000235:genetics; D054884:Host-Pathogen Interactions; D019426:Integrases / Q000235:genetics; D007668:Kidney / Q000382:microbiology / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010976:Platelet Count; D010978:Platelet Factor 4 / Q000097:blood / Q000235:genetics; D012772:Shock, Septic / Q000097:blood / Q000382:microbiology; D013203:Staphylococcal Infections / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D013211:Staphylococcus aureus / Q000276:immunology / Q000472:pathogenicity*; D013997:Time Factors
chemical_list: D016207:Cytokines; D004167:Diphtheria Toxin; D066257:Heparin-binding EGF-like Growth Factor; D010978:Platelet Factor 4; C045073:Cre recombinase; D019426:Integrases
keywords: Staphylococcus aureus; bacteria; blood platelets; sepsis; septic shock