title: Glycoproteomic identification of galectin-3 and -8 ligands in bronchoalveolar lavage of mild asthmatics and healthy subjects.
abstract: BACKGROUND
  Galectins, a family of small carbohydrate binding proteins, have been implicated in regulation of inflammatory reactions, including asthma and fibrosis in the lungs. Galectins are found in cells of the airways and in airway secretions, but their glycoprotein ligands there have only been studied to a very limited extent.
  
  
  METHODS
  Bronchoalveolar lavage (BAL) fluid from mild asthmatics and healthy volunteers were fractionated by affinity chromatography on the immobilized galectins. Total (10-30 μg) and galectin bound (~1-10 μg) protein fractions were identified, quantified and compared using shot-gun proteomics and spectral counts.
  
  
  RESULTS
  About 175 proteins were identified in unfractionated BAL-fluid, and about 100 bound galectin-3 and 60 bound galectin-8. These included plasma glycoproteins, and typical airway proteins such as SP-A2, PIGR and SP-B. The concentration of galectin-binding proteins was 100-300 times higher than the concentration of galectins in BAL.
  
  
  CONCLUSIONS
  The low relative concentration of galectins in BAL makes it likely that functional interactions with glycoproteins occur at sites rich in galectin, such as cells of the airways, rather than the extracellular fluid itself. The profile of galectin bound proteins differed between samples from asthma patients and healthy subjects and correlated with the presence of fibroblasts or eosinophils. This included appearance of a specific galectin-8-binding glycoform of haptoglobin, previously shown to be increased in serum in other inflammatory conditions.
  
  
  CONCLUSIONS
  It is technically feasible to identify galectin-binding glycoproteins in low concentration patient samples such as BAL-fluid, to generate biomedically interesting results. This article is part of a Special Issue entitled Glycoproteomics.
authors.affiliation: MIG (Microbiology, Immunology, Glycobiology), Dept. of Laboratory Medicine Lund, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Cederfur
authors.forename: Johan
authors.initials: J
authors.lastname: Malmström
authors.forename: Kristian
authors.initials: K
authors.lastname: Nihlberg
authors.forename: Mattias
authors.initials: M
authors.lastname: Block
authors.forename: Michael E
authors.initials: ME
authors.lastname: Breimer
authors.forename: Leif
authors.initials: L
authors.lastname: Bjermer
authors.forename: Gunilla
authors.initials: G
authors.lastname: Westergren-Thorsson
authors.forename: Hakon
authors.initials: H
authors.lastname: Leffler
mesh_terms: D000328:Adult; D000818:Animals; D001249:Asthma / Q000378:metabolism* / Q000473:pathology; D018893:Bronchoalveolar Lavage; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D002415:Cats; D005260:Female; D037502:Galectin 3 / Q000032:analysis / Q000378:metabolism*; D037161:Galectins / Q000032:analysis / Q000378:metabolism*; D054794:Glycomics / Q000379:methods*; D006262:Health; D006801:Humans; D006967:Hypersensitivity / Q000378:metabolism / Q000473:pathology; D008024:Ligands; D008297:Male; D011485:Protein Binding; D040901:Proteomics / Q000379:methods; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D037502:Galectin 3; D037161:Galectins; C091991:LGALS8 protein, human; D008024:Ligands