title: Inhibitory effects of lipoteichoic acid from Staphylococcus aureus on platelet function and platelet-monocyte aggregation.
abstract: OBJECTIVE
  Lipoteichoic acid (LTA) from Staphylococcus aureus has been demonstrated to inhibit agonist-stimulated platelet aggregation. However, its effects on platelet inflammatory mediator release and platelet-monocyte aggregation are still unclear. In the present study, LTA is examined for its anti-inflammatory properties and effects on platelet-monocyte aggregation.
  
  
  METHODS
  Blood samples were obtained from 5 healthy volunteers who had taken no medicine in the previous 2 weeks. Washed platelets were prepared and incubated with LTA (0.5-2.0 μg/mL), then platelet aggregation, P-selectin expression, and soluble CD40L (sCD40L) release were measured by light transmission aggregometry, flow cytometry and enzyme-linked immunoassays, respectively. Platelet-monocyte aggregate formation in whole blood was measured by flow cytometry. Thrombin was used as a stimulant.
  
  
  RESULTS
  LTA dose-dependently decreased platelet aggregation from 89.32 ± 10.24% to 36.28 ± 9.01% (P < 0.05), sCD40L release from 3.28 ± 0.76 to 1.13 ± 0.45 ng/mL (P < 0.05) and surface P-selectin expression from 82.01 ± 11.20 to 22.78 ± 6.42% (P < 0.05). In human whole blood, 1.0 μg/mL LTA inhibited platelet-monocyte aggregation from 78.19 ± 10.94 to 38.24 + 8.74% (P < 0.05).
  
  
  CONCLUSIONS
  These results indicate that LTA from S. aureus can inhibit platelet-dependent inflammatory mediator release and platelet-monocyte aggregation. These findings suggest that LTA-mediated functional alteration of platelets may contribute to immune evasion of S. aureus.
authors.affiliation: Department of Internal Medicine, Division of Respiratory and Critical Care, The Third Affiliated Hospital of Sun Yat-Sen University, No. 600, Tianhe Street, Guangzhou, 510630, People's Republic of China. zswbq@163.com
authors.forename: Ben-Quan
authors.initials: BQ
authors.lastname: Wu
authors.forename: Ming-Jun
authors.initials: MJ
authors.lastname: Zhi
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Zhou
authors.forename: Tian-Tuo
authors.initials: TT
authors.lastname: Zhang
mesh_terms: D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D023201:CD40 Ligand / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D019007:P-Selectin / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000378:metabolism*; D013682:Teichoic Acids / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology
chemical_list: D006490:Hemostatics; D008070:Lipopolysaccharides; D019007:P-Selectin; D013682:Teichoic Acids; D023201:CD40 Ligand; C009900:lipoteichoic acid; D013917:Thrombin