title: High-mobility group box-1 protein induces osteogenic phenotype changes in aortic valve interstitial cells.
abstract: OBJECTIVE
  Calcific aortic valve (AV) disease is known to be an inflammation-related process. High-mobility group box-1 (HMGB1) protein and Toll-like receptor 4 (TLR4) have been reported to participate in several inflammatory diseases. The purpose of the present study was to determine whether the HMGB1-TLR4 axis is involved in calcific AV disease, and to evaluate the effect of HMGB1, and its potential mechanisms, on the pro-osteogenic phenotype change of valvular interstitial cells (VICs).
  
  
  METHODS
  Expression of HMGB1 and TLR4 in human calcific AVs was evaluated using immunohistochemical staining and immunoblotting. Cultured VICs were used as an in vitro model. The VICs were stimulated with HMGB1 for analysis, with versus without TLR4 small interfering ribonucleic acid (siRNA), c-Jun N-terminal kinase mitogen-activated protein kinase (JNK MAPK), and nuclear factor kappa-B (NF-κB) inhibitors.
  
  
  RESULTS
  Enhanced accumulation of HMGB1 and TLR4 was observed in calcific valves. Moreover, we found that HMGB1 induced high levels of pro-inflammatory cytokine production and promoted the osteoblastic differentiation and calcification of VICs. In addition, HMGB1 induced phosphorylation of JNK MAPK and NF-κB. However, these effects were markedly suppressed by siRNA silencing of TLR4. In addition, blockade of JNK MAPK and NF-κB phosphorylation prohibited HMGB1-induced production of pro-osteogenic factors, and mineralization of VICs.
  
  
  CONCLUSIONS
  The HMGB1 protein may promote osteoblastic differentiation and calcification of VICs, through the TLR4-JNK-NF-κB signaling pathway.
authors.affiliation: Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Cardiothoracic Surgery, Huangshi Central Hospital, Huangshi, China.
authors.forename: Guangxia
authors.initials: G
authors.lastname: Wei
authors.affiliation: Department of Gerontology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
authors.forename: Pingping
authors.initials: P
authors.lastname: Liao
authors.affiliation: Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China. Electronic address: dongnianguo@hotmail.com.
authors.forename: Nianguo
authors.initials: N
authors.lastname: Dong
mesh_terms: D001021:Aortic Valve / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002114:Calcinosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D024243:HMGB1 Protein / Q000378:metabolism* / Q000494:pharmacology; D006349:Heart Valve Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D010641:Phenotype; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D024243:HMGB1 Protein; C585491:HMGB1 protein, human; D016328:NF-kappa B; D047428:Protein Kinase Inhibitors; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D048031:JNK Mitogen-Activated Protein Kinases
keywords: HMGB1; TLR4; aortic valve calcification; osteoblastic differentiation