title: Inhaled tolafentrine reverses pulmonary vascular remodeling via inhibition of smooth muscle cell migration.
abstract: BACKGROUND
  The aim of the study was to assess the chronic effects of combined phosphodiesterase 3/4 inhibitor tolafentrine, administered by inhalation, during monocrotaline-induced pulmonary arterial hypertension (PAH) in rats.
  
  
  METHODS
  CD rats were given a single subcutaneous injection of monocrotaline to induce PAH. Four weeks after, rats were subjected to inhalation of tolafentrine or sham nebulization in an unrestrained, whole body aerosol exposure system. In these animals (i) the acute pulmonary vasodilatory efficacy of inhaled tolafentrine (ii) the anti-remodeling effect of long-term inhalation of tolafentrine (iii) the effects of tolafentrine on the expression profile of 96 genes encoding cell adhesion and extracellular matrix regulation were examined. In addition, the inhibitory effect of tolafentrine on ex vivo isolated pulmonary artery SMC cell migration was also investigated.
  
  
  RESULTS
  Monocrotaline injection provoked severe PAH (right ventricular systolic pressure increased from 25.9 +/- 4.0 to 68.9 +/- 3.2 after 4 weeks and 74.9 +/- 5.1 mmHg after 6 weeks), cardiac output depression and right heart hypertrophy. The media thickness of the pulmonary arteries and the proportion of muscularization of small precapillary resistance vessels increased dramatically, and the migratory response of ex-vivo isolated pulmonary artery smooth muscle cells (PASMC) was increased. Micro-arrays and subsequent confirmation with real time PCR demonstrated upregulation of several extracellular matrix regulation and adhesion genes, such as matrixmetalloproteases (MMP) 2, 8, 9, 10, 11, 12, 20, Icam, Itgax, Plat and serpinb2. When chronically nebulized from day 28 to 42 (12 daily aerosol maneuvers), after full establishment of severe pulmonary hypertension, tolafentrine reversed about 60% of all hemodynamic abnormalities, right heart hypertrophy and monocrotaline-induced structural lung vascular changes, including the proportion of pulmonary artery muscularization. The upregulation of extracellular matrix regulation and adhesion genes was reduced by nearly 80% by inhalation of the tolafentrine. When assessed in vitro, tolafentrine blocked the enhanced PASMC migratory response.
  
  
  CONCLUSIONS
  In conclusion, we demonstrate for the first time that inhalation of combined PDE3/4 inhibitor reverses pulmonary hypertension fully developed in response to monocrotaline in rats. This "reverse-remodeling" effect includes structural changes in the lung vascular wall and key molecular pathways of matrix regulation, concomitant with 60% normalization of hemodynamics.
authors.affiliation: University of Giessen Lung Center, Medical Clinic II/V, Giessen, Germany. Soni.Pullamsetti@innere.med.uni-giessen.de
authors.forename: Soni
authors.initials: S
authors.lastname: Pullamsetti
authors.forename: Stefanie
authors.initials: S
authors.lastname: Krick
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Yilmaz
authors.forename: Hossein Ardeschir
authors.initials: HA
authors.lastname: Ghofrani
authors.forename: Christian
authors.initials: C
authors.lastname: Schudt
authors.forename: Norbert
authors.initials: N
authors.lastname: Weissmann
authors.forename: Beate
authors.initials: B
authors.lastname: Fuchs
authors.forename: Werner
authors.initials: W
authors.lastname: Seeger
authors.forename: Friedrich
authors.initials: F
authors.lastname: Grimminger
authors.forename: Ralph Theo
authors.initials: RT
authors.lastname: Schermuly
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D002465:Cell Movement / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005109:Extracellular Matrix / Q000187:drug effects / Q000648:ultrastructure*; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology*; D008297:Male; D016686:Monocrotaline; D032389:Myocytes, Smooth Muscle / Q000187:drug effects*; D009287:Naphthyridines / Q000008:administration & dosage*; D051381:Rats
chemical_list: D009287:Naphthyridines; C094030:tolafentrine; D016686:Monocrotaline