title: Platelets Toll-like receptor-4 in Crohns disease.
abstract: BACKGROUND
  Platelets are activated in Crohn's disease (CD) and interplay with leukocytes. Engagement of Toll-like receptor-4 (TLR-4), which is expressed in human platelets, may be involved in crosstalks between platelets and leukocytes leading to their mutual activation for host defense.
  
  
  METHODS
  Human neutrophil peptides (HNPs), lipoprotein binding peptides, and sCD14 were determined by enzyme-linked immunosorbent assays in 42 patients with active CD, in 43 patients with CD in remission, and in 30 healthy individuals. Neutrophil-platelet aggregates and binding of the TLR-4 monoclonal antibody to platelets were determined by flow cytometry.
  
  
  RESULTS
  Levels of HNPs were higher in patients with CD than in controls (P = 0.0003 vs. active CD and P = 0.01 vs. CD in remission). Likewise, neutrophils with adhering platelets were higher in patients with active CD than in controls (P = 0.004). Binding of the TLR-4 antibody in patients with active CD was similar to that in controls, while patients in remission had significantly higher binding capacities (P = 0.59 and P = 0.003). Incubation of plasma from patients with active disease or patients in remission with platelets from healthy controls confirmed lower binding of the TLR-4 antibody in the presence of plasma from active diseased patients compared to controls (P = 0.039), possibly due to high levels of lipopolysaccharides, as suggested by high levels of sCD14 and lipoprotein binding protein.
  
  
  CONCLUSIONS
  Our study indicates involvement of platelet TLR-4 in enhancing the secretion of antimicrobial peptides from neutrophils. While platelet aggregation can be due to a variety of mechanisms in inflammatory disease, the mutual activation of platelets and neutrophils may augment host defense.
authors.affiliation: Division of Cardiothoracic and Vascular Anesthesia and Intensive Care, Department of Anesthesiology, General Intensive Care and Pain Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Werner
authors.initials: W
authors.lastname: Schmid
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Novacek
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Vogelsang
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Pavol
authors.initials: P
authors.lastname: Papay
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Primas
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Eser
authors.affiliation: Department of Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Panzer
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D002097:C-Reactive Protein / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D016022:Case-Control Studies; D002450:Cell Communication / Q000502:physiology; D003424:Crohn Disease / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D018375:Neutrophil Activation / Q000502:physiology; D009504:Neutrophils / Q000378:metabolism; D015539:Platelet Activation / Q000502:physiology; D010974:Platelet Aggregation / Q000502:physiology; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D023084:alpha-Defensins / Q000378:metabolism*; D000099231:Lipopolysaccharide-Binding Protein
chemical_list: D000209:Acute-Phase Proteins; D002097:C-Reactive Protein; D002352:Carrier Proteins; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D051197:Toll-Like Receptor 4; D023084:alpha-Defensins; D000099231:Lipopolysaccharide-Binding Protein; C495345:TLR4 protein, human
keywords: Crohn's disease; Toll-like receptor-4; human neutrophil α-defensins