title: Vitamin D receptor activators inhibit vascular smooth muscle cell mineralization induced by phosphate and TNF-α.
abstract: BACKGROUND
  Vascular calcification is a highly regulated process. Tumor necrosis factor-α (TNF-α) has been shown to accelerate the highly regulated osteogenic process in vascular smooth muscle cells (VSMCs). Vitamin D receptor activators (VDRAs) have been associated with beneficial cardiovascular outcomes in patients with chronic kidney disease. We examined whether maxacalcitol, a vitamin D(3) analog, exhibits a suppressive effect on VSMC mineralization induced by phosphate and TNF-α.
  
  
  METHODS
  Human VSMCs were treated with either vehicle, maxacalcitol (10(-9) to 10(-7) M), or calcitriol (10(-9) to 10(-7) M) in 2.5 mM of phosphate media with TNF-α (1 ng/mL) for 9 days. VSMC mineralization was determined and expression of genes associated with the osteogenic process was examined by real-time reverse transcription-polymerase chain reaction. Expression of matrix metalloproteinase-2 (MMP-2) messenger RNA (mRNA) in VSMCs and MMP-2 protein in media was also analyzed.
  
  
  RESULTS
  Vehicle-treated VSMCs exhibited massive mineralization, which was inhibited by maxacalcitol in a concentration-dependent manner. Calcitriol also inhibited the mineralization. While vehicle-treated VSMCs exhibited increased mRNA expression of genes associated with the osteogenic process (Cbfa1/Runx2 and osteocalcin) compared with VSMCs grown in normal media without TNF-α (control), maxacalcitol and calcitriol suppressed the increase in mRNA species. Furthermore, vehicle-treated VSMCs exhibited increased MMP-2 mRNA and protein in the media that were suppressed notably by maxacalcitol.
  
  
  CONCLUSIONS
  Both the VDRAs abrogated the acceleration of the osteogenic process induced by phosphate and TNF-α in VSMCs, which was linked to inhibition of mineralization in VSMCs. MMP-2 blockade by VDRAs may contribute to an inhibitory effect on vascular calcification.
authors.affiliation: Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Yumie
authors.initials: Y
authors.lastname: Aoshima
authors.forename: Masahide
authors.initials: M
authors.lastname: Mizobuchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ogata
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kumata
authors.forename: Ai
authors.initials: A
authors.lastname: Nakazawa
authors.forename: Fumiko
authors.initials: F
authors.lastname: Kondo
authors.forename: Naoko
authors.initials: N
authors.lastname: Ono
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Koiwa
authors.forename: Eriko
authors.initials: E
authors.lastname: Kinugasa
authors.forename: Tadao
authors.initials: T
authors.lastname: Akizawa
mesh_terms: D002117:Calcitriol / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D010710:Phosphates / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000187:drug effects* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D061205:Vascular Calcification / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives
chemical_list: D010710:Phosphates; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D014409:Tumor Necrosis Factor-alpha; D014807:Vitamin D; D020778:Matrix Metalloproteinase 2; D002117:Calcitriol; C051883:maxacalcitol