title: Sarcoidosis, alveolar β-actin and pulmonary fibrosis.
abstract: BACKGROUND
  Sarcoidosis is a multisystem granulomatous disease of unknown aetiology. Proteins present within the alveolar space early in sarcoidosis disease may provide an insight into novel mechanisms for the development of fibrotic disease and in particular pulmonary fibrosis.
  
  
  METHODS
  A modified two-dimensional difference gel electrophoresis protocol was applied to the human bronchoalveolar lavage fluid (hBALF) of four patients with non-persistent pulmonary interstitial disease at 4-year follow-up (defined as mild disease) and four patients who developed pulmonary interstitial disease at 4-year follow-up (defined as severe disease). The protein β-actin was identified by LC-MS/MS from a preparative gel and found to be significantly elevated in early lavages from the severe disease group. To look at the potential pro-fibrotic effects of this protein, primary human pulmonary fibroblasts (CCD-19Lu) were treated with recombinant β-actin following which qPCR and ELISA assays were used to measure any effects.
  
  
  RESULTS
  We found that β-actin levels were significantly elevated in early hBALF samples in patients who subsequently developed severe disease when compared to the mild group. Treating primary human pulmonary fibroblasts with recombinant β-actin led to enhanced gene expression of the pro-fibrotic markers alpha smooth muscle actin and collagen 1 as well as the increased secretion of interleukin-13 and metalloproteinases 3 and 9.
  
  
  CONCLUSIONS
  Free β-actin within the lungs of sarcoidosis patients potentially may contribute to disease pathogenesis particularly in the context of abnormal remodelling and the development of pulmonary fibrosis.
authors.affiliation: School of Medicine and Medical Science, Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland. gordon.cooke@ucd.ie.
authors.forename: G
authors.initials: G
authors.lastname: Cooke
authors.forename: P
authors.initials: P
authors.lastname: Govender
authors.forename: C J
authors.initials: CJ
authors.lastname: Watson
authors.forename: M E
authors.initials: ME
authors.lastname: Armstrong
authors.forename: D N
authors.initials: DN
authors.lastname: O'Dwyer
authors.forename: M P
authors.initials: MP
authors.lastname: Keane
authors.forename: R
authors.initials: R
authors.lastname: King
authors.forename: A
authors.initials: A
authors.lastname: Tynan
authors.forename: M
authors.initials: M
authors.lastname: Dunn
authors.forename: S C
authors.initials: SC
authors.lastname: Donnelly
mesh_terms: D000199:Actins / Q000378:metabolism*; D001992:Bronchoalveolar Lavage Fluid; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008171:Lung Diseases / Q000378:metabolism*; D011658:Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology; D012507:Sarcoidosis / Q000378:metabolism*
chemical_list: D000199:Actins