title: Toll-like receptor-4 message is up-regulated in lipopolysaccharide-exposed rat lung pericytes.
abstract: BACKGROUND
  Pericytes are multifunctional, polymorphic perivascular cells that lie within the microvessel basal lamina, are located on the abluminal side of endothelial cells, and are thought to play a regulatory role in capillary leak observed in sepsis. Toll-Like receptor 4 (TLR-4) has been implicated as the proximal transmembrane receptor for the LPS/CD 14 complex during the activation of lipopolysacharide (LPS)-induced sepsis. It is our hypothesis that TLR-4 is present on lung pericytes and is up-regulated in response to LPS.
  
  
  METHODS
  Rat microvascular lung pericytes were isolated and cultured. Cells from passage 3-5 were used and treated with LPS (control, 10 ng/mL, and 100 ng/mL) for 18 h. Immunostaining and immunoblotting were performed to detect the presence of CD-14, TLR-2, and TLR-4. Real-time polymerase chain reaction was used to analyze the presence and quantity of mRNA for CD-14, TLR-2, and TLR-4.
  
  
  RESULTS
  Immunostaining and immunoblotting revealed the presence of CD-14, TLR-2, and TLR-4 in pericytes from each treatment group, and real-time polymerase chain reaction confirmed the presence of mRNA for CD-14, TLR-2, and TLR-4. An increase in the mRNA was observed in CD-14, TLR-2, and TLR-4 in the presence of increasing LPS 4 h after treatment. At 18 h after LPS treatment, a decrease in mRNA was noted.
  
  
  CONCLUSIONS
  The up-regulation of TLR-4 in the presence of increasing LPS suggests its importance in pericyte LPS-induced activation. Pericyte TLR-4 recognition of LPS could play a role in capillary leak seen in sepsis. These data also demonstrates that pericytes, once thought to be passive participants in the inflammatory cascade, may be active members.
authors.affiliation: Wayne State University/Detroit Medical Center, Detroit, Michigan, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Edelman
authors.forename: Yang
authors.initials: Y
authors.lastname: Jiang
authors.forename: James
authors.initials: J
authors.lastname: Tyburski
authors.forename: Robert F
authors.initials: RF
authors.lastname: Wilson
authors.forename: Christopher
authors.initials: C
authors.lastname: Steffes
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D018950:Lipopolysaccharide Receptors / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D020286:Pericytes / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051195:Toll-Like Receptor 2 / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000032:analysis / Q000235:genetics*; D015854:Up-Regulation
chemical_list: D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; C495343:Tlr2 protein, rat; C495347:Tlr4 protein, rat; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4