title: CD40 ligand increases expression of its receptor CD40 in human coronary artery endothelial cells.
abstract: BACKGROUND
  Recently, CD40 ligand (CD40L) and its receptor CD40 have been implicated in atherosclerosis. Clinical data showed that elevated CD40L levels are associated with a high risk of cardiovascular events. The aim of this study was to investigate whether CD40L could affect the expression of its membrane receptor CD40 as a feedback mechanism by which CD40L could enhance its functions in human coronary artery endothelial cells (HCAECs).
  
  
  METHODS
  The HCAECs were treated with human soluble CD40L, and the messenger RNA (mRNA) and protein levels of CD40 were determined by real-time polymerase chain reaction and Western blot analysis, respectively. The specific effect of CD40L was confirmed by a blocking experiment with antibody against CD40L. Involvements of oxidative stress and mitogen-activated protein kinases (MAPKs) were also studied with antioxidant seleno-L-methionine (SeMet) and MAPK inhibitors such as extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor.
  
  
  RESULTS
  When HCAECs were cultured with CD40L (5 microg/mL) for 24 hours, CD40 mRNA levels were increased by 79% compared with controls (P < .05). Similarly, Western blot analysis showed an 80% increase in CD40 protein levels (P < .05). The CD40L-induced increase in CD40 mRNA levels were blocked specifically by anti-CD40L antibody. Antioxidant SeMet and specific ERK1/2 inhibitor (PD98059) also effectively blocked CD40L-induced CD40 mRNA increase.
  
  
  CONCLUSIONS
  These data demonstrate that clinically relevant concentration of CD40L increased the expression of its receptor CD40 in HCAECs. The CD40L-induced upregulation of CD40 may be mediated by oxidative stress and ERK1/2 activation. This study suggests a new mechanism by which CD40L could enhance its biologic functions in the vascular system and contribute to endothelial dysfunction and vascular disease.
authors.affiliation: Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Chai
authors.forename: Shaoyu
authors.initials: S
authors.lastname: Yan
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Rongxin
authors.initials: R
authors.lastname: Zhang
authors.forename: Peter H
authors.initials: PH
authors.lastname: Lin
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Yao
authors.forename: Changyi
authors.initials: C
authors.lastname: Chen
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism*; D023201:CD40 Ligand / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D018929:Cell Culture Techniques; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D025461:Feedback, Physiological / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D012645:Selenomethionine / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D019013:CD40 Antigens; D005419:Flavonoids; D012333:RNA, Messenger; D023201:CD40 Ligand; D012645:Selenomethionine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one