title: Preliminary identification of differentially expressed tear proteins in keratoconus.
abstract: OBJECTIVE
  To examine the proteins differentially expressed in the tear film of people with keratoconus and normal subjects.
  
  
  METHODS
  Unstimulated tears from people with keratoconus (KC) and controls (C) were collected using a capillary tube. Tear proteins from people with KC and controls were partitioned using a novel in-solution electrophoresis, Microflow 10 (ProteomeSep), and analyzed using linear ion trap quadrupole fourier transform mass spectrometry. Spectral counting was used to quantify the individual tear proteins.
  
  
  RESULTS
  Elevated levels of cathepsin B (threefold) were evident in the tears of people with KC. Polymeric immunoglobulin receptor (ninefold), fibrinogen alpha chain (eightfold), cystatin S (twofold), and cystatin SN (twofold) were reduced in tears from people with KC. Keratin type-1 cytoskeletal-14 and keratin type-2 cytoskeletal-5 were present only in the tears of people with KC.
  
  
  CONCLUSIONS
  The protein changes in tears, that is, the decrease in protease inhibitors and increase in proteases, found in the present and other previously published studies reflect the pathological events involved in KC corneas. Further investigations into tear proteins may help elucidate the underlying molecular mechanisms of KC, which could result in better treatment options.
authors.affiliation: School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia ; School of Medicine, Deakin University, Waurn Ponds, Victoria, Australia ; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.
authors.forename: Sivaraman A
authors.initials: SA
authors.lastname: Balasubramanian
authors.forename: Valerie C
authors.initials: VC
authors.lastname: Wasinger
authors.forename: David C
authors.initials: DC
authors.lastname: Pye
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D019781:Corneal Topography; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D063990:Gene Ontology; D006801:Humans; D007640:Keratoconus / Q000378:metabolism*; D008297:Male; D040901:Proteomics
chemical_list: D005136:Eye Proteins; C042434:tear proteins