title: Low dose LPS does not increase TLR4 expression on monocytes in a human in vivo model.
abstract: OBJECTIVE
  Toll like receptor 4 (TLR4) is the major recognition receptor for lipopolysaccharides and plays a major role in the inflammatory response. CD11b is expressed on the surface of many leukocytes including monocytes. The CD11b/CD18 complex is involved in the inflammatory response by mediating migration and adhesion of leukocytes. The aim of this human in vivo study was to investigate the expression of TLR4 and CD11b on the surface of human monocytes after in vivo low-dose LPS stimulation.
  
  
  METHODS
  We performed a double-blind, randomized crossover study with 16 healthy males who received a bolus injection of bacterial lipopolysaccharide (LPS; 0.4ng/kg) or normal saline. Vital parameters, blood counts, serum cytokine levels, the expression of TLR4, and CD11b on CD14 positive cells were analyzed.
  
  
  RESULTS
  The experimentally induced inflammatory response was reflected by transient increases in body temperature, circulating leukocyte numbers, and plasma levels of pro- (TNF-α, IL-6) and anti-inflammatory cytokines (IL-10, IL-1ra). In contrast to a significant increase in CD11b expression, no changes in TLR4 expression on circulating monocytes were detectable.
  
  
  CONCLUSIONS
  Early changes in TLR4 expression on circulating monocytes are not necessarily part of the inflammatory response to low dose LPS in humans whereas the detected increase of CD11b expression might already be sufficient for optimized recognition and signalling.
authors.affiliation: Department of Orthopaedic Trauma Surgery, Medical School of the RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany; Department of Trauma Surgery, University Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: plichte@ukaachen.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Lichte
authors.affiliation: Institute of Medical Psychology and Behavioral Immunobiology, University Essen Medical School, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: Jan-Sebastian.Grigoleit@uk-essen.de.
authors.forename: Jan-Sebastian
authors.initials: JS
authors.lastname: Grigoleit
authors.affiliation: Department of Trauma Surgery, University Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: eva_st@web.de.
authors.forename: Eva Maria
authors.initials: EM
authors.lastname: Steiner
authors.affiliation: Institute of Medical Psychology and Behavioral Immunobiology, University Essen Medical School, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: jennifer.kullmann@uk-essen.de.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Kullmann
authors.affiliation: Institute of Medical Psychology and Behavioral Immunobiology, University Essen Medical School, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: manfred.schedlowski@uk-essen.de.
authors.forename: Manfred
authors.initials: M
authors.lastname: Schedlowski
authors.affiliation: Department of Orthopaedic Trauma Surgery, Medical School of the RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany. Electronic address: reiner.oberbeck@uk-essen.de.
authors.forename: Reiner
authors.initials: R
authors.lastname: Oberbeck
authors.affiliation: Department of Orthopaedic Trauma Surgery, Medical School of the RWTH Aachen, Pauwelsstr. 30, 52074 Aachen, Germany; Department of Trauma Surgery, University Essen Medical School, Hufelandstrasse 55, 45122 Essen, Germany. Electronic address: pkobbe@ukaachen.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kobbe
mesh_terms: D001772:Blood Cell Count; D001794:Blood Pressure / Q000187:drug effects; D039481:CD11b Antigen / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000097:blood; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D008954:Models, Biological; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*
chemical_list: D039481:CD11b Antigen; D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4