title: Activation of TLR3 induces osteogenic responses in human aortic valve interstitial cells through the NF-κB and ERK1/2 pathways.
abstract: Calcific aortic valve disease (CAVD) is characterized by chronic inflammation and progressive calcification in valve leaflets. Aortic valve interstitial cells (AVICs) play a critical role in the pathogenesis of CAVD. Previous studies show that stimulation of Toll-like receptor (TLR) 2 or TLR4 in AVICs in vitro up-regulates the expression of osteogenic mediators. Double-stranded RNA (dsRNA) can activate pro-inflammatory signaling through TLR3, the NLRP3 inflammasome and RIG-I-like receptors. The objective of this study is to determine the effect of dsRNA on AVIC osteogenic activities and the mechanism of its action.
  
  
  RESULTS
  AVICs isolated from normal human valves were exposed to polyinosinic-polycytidylic acid [poly(I:C)], a mimic of dsRNA. Treatment with poly(I:C) increased the production of bone morphogenetic protein-2 (BMP-2), transforming growth factor beta-1 (TGF-β1) and alkaline phosphatase (ALP), and resulted in calcium deposit formation. Poly(I:C) induced the phosphorylation of NF-κB and ERK1/2. Knockdown of TLR3 essentially abrogated NF-κB and ERK1/2 phosphorylation, and markedly reduced the effect of poly(I:C) on the production of BMP-2, TGF-β1 and ALP. Further, inhibition of either NF-κB or ERK1/2 markedly reduced the levels of BMP-2, TGF-β1 and ALP in cells exposed to poly(I:C).
  
  
  CONCLUSIONS
  Poly(I:C) up-regulates the production of BMP-2, TGF-β1 and ALP, and promotes calcium deposit formation in human AVICs. The pro-osteogenic effect of poly(I:C) is mediated primarily by TLR3 and the NF-κB and ERK1/2 pathways. These findings suggest that dsRNA, when present in aortic valve tissue, may promote CAVD progression through up-regulation of AVIC osteogenic activities.
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA. ; 2. Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China;
authors: Qiong
authors: Q
authors: Zhan
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA. ; 3. Departments of Pathophysiology, Southern Medical University, Guangzhou 510515, China;
authors: Rui
authors: R
authors: Song
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA. ; 2. Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China;
authors: Qingchun
authors: Q
authors: Zeng
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA. ; 4. Medical Research Center of Guangdong General Hospital, Southern Medical University. Guangzhou 510080, China.
authors: Qingzhou
authors: Q
authors: Yao
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA.
authors: Lihua
authors: L
authors: Ao
authors: 2. Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China;
authors: Dingli
authors: D
authors: Xu
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA.
authors: David A
authors: DA
authors: Fullerton
authors: 1. Department of Surgery, University of Colorado Denver, Aurora, CO 80045, USA.
authors: Xianzhong
authors: X
authors: Meng
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001021:Aortic Valve / Q000378:metabolism / Q000473:pathology; D001024:Aortic Valve Stenosis / Q000378:metabolism; D000082882:Bicuspid Aortic Valve Disease; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism; D002114:Calcinosis / Q000378:metabolism; D002478:Cells, Cultured; D006330:Heart Defects, Congenital / Q000378:metabolism; D006349:Heart Valve Diseases / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D016328:NF-kappa B / Q000378:metabolism*; D010012:Osteogenesis / Q000502:physiology; D051196:Toll-Like Receptor 3 / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D016328:NF-kappa B; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D053773:Transforming Growth Factor beta1; D000469:Alkaline Phosphatase
keywords: Aortic valve interstitial cells.; BMP-2; Calcification; TGF-β1; TLR3