title: Dexamethasone induces apoptosis in pulmonary arterial smooth muscle cells.
abstract: BACKGROUND
  Dexamethasone suppressed inflammation and haemodynamic changes in an animal model of pulmonary arterial hypertension (PAH). A major target for dexamethasone actions is NF-κB, which is activated in pulmonary vascular cells and perivascular inflammatory cells in PAH. Reverse remodelling is an important concept in PAH disease therapy, and further to its anti-proliferative effects, we sought to explore whether dexamethasone augments pulmonary arterial smooth muscle cell (PASMC) apoptosis.
  
  
  METHODS
  Analysis of apoptosis markers (caspase 3, in-situ DNA fragmentation) and NF-κB (p65 and phospho-IKK-α/β) activation was performed on lung tissue from rats with monocrotaline (MCT)-induced pulmonary hypertension (PH), before and after day 14-28 treatment with dexamethasone (5 mg/kg/day). PASMC were cultured from this rat PH model and from normal human lung following lung cancer surgery. Following stimulation with TNF-α (10 ng/ml), the effects of dexamethasone (10(-8)-10(-6) M) and IKK2 (NF-κB) inhibition (AS602868, 0-3 μM (0-3×10(-6) M) on IL-6 and CXCL8 release and apoptosis was determined by ELISA and by Hoechst staining. NF-κB activation was measured by TransAm assay.
  
  
  RESULTS
  Dexamethasone treatment of rats with MCT-induced PH in vivo led to PASMC apoptosis as displayed by increased caspase 3 expression and DNA fragmentation. A similar effect was seen in vitro using TNF-α-simulated human and rat PASMC following both dexamethasone and IKK2 inhibition. Increased apoptosis was associated with a reduction in NF-κB activation and in IL-6 and CXCL8 release from PASMC.
  
  
  CONCLUSIONS
  Dexamethasone exerted reverse-remodelling effects by augmenting apoptosis and reversing inflammation in PASMC possibly via inhibition of NF-κB. Future PAH therapies may involve targeting these important inflammatory pathways.
authors.affiliation: Pulmonary Hypertension Service, Royal Brompton Hospital, London, SW3 6NP, UK. l.price@imperial.ac.uk.
authors.forename: Laura C
authors.initials: LC
authors.lastname: Price
authors.affiliation: Pulmonary Hypertension Service, Royal Brompton Hospital, London, SW3 6NP, UK.
authors.forename: Dongmin
authors.initials: D
authors.lastname: Shao
authors.affiliation: Pulmonary Hypertension Service, Royal Brompton Hospital, London, SW3 6NP, UK.|Department of Geriatrics, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Meng
authors.affiliation: Service de Pneumologie et Réanimation Respiratoire, Hôpital Bicêtre, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Perros
authors.affiliation: Pulmonary Hypertension Service, Royal Brompton Hospital, London, SW3 6NP, UK.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Garfield
authors.affiliation: Department of Histopathology, Royal Brompton Hospital, London, SW3 6NP, UK.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Service de Pneumologie et Réanimation Respiratoire, Hôpital Bicêtre, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France.
authors.forename: David
authors.initials: D
authors.lastname: Montani
authors.affiliation: Service de Pneumologie et Réanimation Respiratoire, Hôpital Bicêtre, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France.
authors.forename: Peter
authors.initials: P
authors.lastname: Dorfmuller
authors.affiliation: Service de Pneumologie et Réanimation Respiratoire, Hôpital Bicêtre, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Humbert
authors.affiliation: Airways Disease Section, National Heart and Lung Institute, Imperial College London, Dovehouse Street, London, SW3 6LY, UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Adcock
authors.affiliation: Pulmonary Hypertension Service, Royal Brompton Hospital, London, SW3 6NP, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wort
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D020672:I-kappa B Proteins / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D016686:Monocrotaline; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D011651:Pulmonary Artery / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism; D066253:Vascular Remodeling / Q000187:drug effects*
chemical_list: D000893:Anti-Inflammatory Agents; D016207:Cytokines; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D018836:Inflammation Mediators; C498145:Rela protein, rat; D051996:Transcription Factor RelA; D016686:Monocrotaline; D003907:Dexamethasone; C505410:Casp3 protein, rat; D053148:Caspase 3