title: Lymphangiogenesis in aortic valve stenosis--novel regulatory roles for valvular myofibroblasts and mast cells.
abstract: OBJECTIVE
  To investigate mechanisms of lymphangiogenesis in aortic valve stenosis (AS).
  
  
  METHODS
  Lymphatic vessels were visualized with LYVE-1 staining in 20 control, 5 sclerotic, and 40 stenotic human aortic valves. Vascular endothelial growth factors (VEGFs) VEGF-C and VEGF-D, and their lymphangiogenic receptor VEGFR-3, and the angiogenic VEGFR-2 were analysed by quantitative real-time PCR and immunohistochemistry. Cultured myofibroblasts derived from human stenotic aortic valves, and cultured human mast cells were used to study VEGF-C regulation, and VEGF-C and VEGF-A were quantified from cell culture media by enzyme immunoassays.
  
  
  RESULTS
  Lymphatic vessels, VEGF-C, VEGF-D, VEGFR-3 and VEGFR-2 all were present in the aortic valves. In AS, the number of lymphatic vessels and the expression of VEGF-D, VEGFR-3, and VEGFR-2 were increased. Moreover, the numbers of lymphatic vessels correlated positively with those of neovessels (r = 0.525, p = 0.001) and mast cells (r = 0.374, p = 0.017). Cultured valvular myofibroblasts produced VEGF-C, and addition of tumour necrosis factor alpha (TNF-α) to the cells augmented its secretion. In contrast, proteases released by activated human mast cells degraded VEGF-C.
  
  
  CONCLUSIONS
  These results show that lymphangiogenesis is induced in advancing AS. Furthermore, valvular myofibroblasts and activated mast cells were identified as novel regulators of lymphangiogenesis in aortic valves.
authors.affiliation: Wihuri Research Institute, Kalliolinnantie 4, 00140 Helsinki, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Syväranta
authors.forename: Satu
authors.initials: S
authors.lastname: Helske
authors.forename: Jani
authors.initials: J
authors.lastname: Lappalainen
authors.forename: Markku
authors.initials: M
authors.lastname: Kupari
authors.forename: Petri T
authors.initials: PT
authors.lastname: Kovanen
mesh_terms: D001021:Aortic Valve / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D042583:Lymphangiogenesis; D042601:Lymphatic Vessels / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008407:Mast Cells / Q000378:metabolism* / Q000473:pathology; D058628:Myofibroblasts / Q000378:metabolism* / Q000473:pathology; D010447:Peptide Hydrolases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics / Q000378:metabolism; D042643:Vascular Endothelial Growth Factor D / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: C119248:LYVE1 protein, human; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C467486:VEGFC protein, human; D042582:Vascular Endothelial Growth Factor C; D042643:Vascular Endothelial Growth Factor D; D033921:Vesicular Transport Proteins; D040301:Vascular Endothelial Growth Factor Receptor-2; D040321:Vascular Endothelial Growth Factor Receptor-3; D010447:Peptide Hydrolases