title: Wnt coreceptor Lrp5 is a driver of idiopathic pulmonary fibrosis.
abstract: BACKGROUND
  Wnt/β-catenin signaling has been implicated in lung fibrosis, but how this occurs and whether expression changes in Wnt pathway components predict disease progression is unknown.
  
  
  OBJECTIVE
  To determine whether the Wnt coreceptor Lrp5 drives pulmonary fibrosis in mice and is predictive of disease severity in humans.
  
  
  METHODS
  We examined mice with impaired Wnt signaling caused by loss of the Wnt coreceptor Lrp5 in models of lung fibrosis induced by bleomycin or an adenovirus encoding an active form of transforming growth factor (TGF)-β. We also analyzed gene expression in peripheral blood mononuclear cells (PBMC) from patients with idiopathic pulmonary fibrosis (IPF).
  
  
  RESULTS
  In patients with IPF, analysis of peripheral blood mononuclear cells revealed that elevation of positive regulators, Lrp5 and 6, was independently associated with disease progression. LRP5 was also associated with disease severity at presentation in an additional cohort of patients with IPF. Lrp5 null mice were protected against bleomycin-induced pulmonary fibrosis, an effect that was phenocopied by direct inhibition of β-catenin signaling by the small molecular inhibitor of β-catenin responsive transcription. Transplantation of Lrp5 null bone marrow cells into wild-type mice did not limit fibrosis. Instead, Lrp5 loss was associated with reduced TGF-β production by alveolar type 2 cells and leukocytes. Consistent with a role of Lrp5 in the activation of TGF-β, Lrp5 null mice were not protected against lung fibrosis induced by TGF-β.
  
  
  CONCLUSIONS
  We show that the Wnt coreceptor, Lrp5, is a genetic driver of lung fibrosis in mice and a marker of disease progression and severity in humans with IPF. Evidence that TGF-β signaling can override a loss in Lrp5 has implications for patient selection and timing of Wnt pathway inhibitors in lung fibrosis.
authors.affiliation: 1 Division of Pulmonary and Critical Care Medicine and.
authors.forename: Anna P
authors.initials: AP
authors.lastname: Lam
authors.forename: Jose D
authors.initials: JD
authors.lastname: Herazo-Maya
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sennello
authors.forename: Annette S
authors.initials: AS
authors.lastname: Flozak
authors.forename: Susan
authors.initials: S
authors.lastname: Russell
authors.forename: Gökhan M
authors.initials: GM
authors.lastname: Mutlu
authors.forename: G R Scott
authors.initials: GR
authors.lastname: Budinger
authors.forename: Ramanuj
authors.initials: R
authors.lastname: DasGupta
authors.forename: John
authors.initials: J
authors.lastname: Varga
authors.forename: Naftali
authors.initials: N
authors.lastname: Kaminski
authors.forename: Cara J
authors.initials: CJ
authors.lastname: Gottardi
mesh_terms: D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D018450:Disease Progression; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000209:etiology / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D060492:Low Density Lipoprotein Receptor-Related Protein-5 / Q000378:metabolism*; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism
chemical_list: D015415:Biomarkers; C495267:CTNNB1 protein, mouse; C555482:LRP5 protein, human; C555475:LRP6 protein, human; D060492:Low Density Lipoprotein Receptor-Related Protein-5; D060488:Low Density Lipoprotein Receptor-Related Protein-6; C555483:Lrp5 protein, mouse; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D051176:beta Catenin
keywords: Wnt/β-catenin signaling; lung fibrosis; peripheral blood mononuclear cell