title: Elevated salivary protein in Parkinson's disease and salivary DJ-1 as a potential marker of disease severity.
abstract: BACKGROUND
  There is an urgent need to identify robust biomarkers for Parkinson's disease (PD). Previous studies have shown changes in composition and secretion of saliva in patients with PD, including an increase in salivary DJ-1 concentration. Autonomic dysfunction is a known feature of PD and could contribute to abnormal salivary gland function.
  
  
  METHODS
  In this pilot cross-sectional study, characterisation of the saliva of 16 patients with PD and 22 age-matched controls was performed. Salivary DJ-1 concentration was measured with quantitative immunoblotting; total protein concentration with a BCA assay and spectrophotometry; amylase with an amylase activity assay; albumin with an ELISA and mucin concentration with periodic-acid Schiff staining of SDS-gels.
  
  
  RESULTS
  Patient saliva showed an increase in both total protein concentration (8.4 vs 5.0 mg/ml, p = 0.0002) and DJ-1 concentration (0.84 vs 0.42 μg/ml, p = 0.001), but there was no difference in salivary DJ-1 after adjusting for total protein concentration. In patients, adjusted DJ-1 levels correlated with disease severity measured with the MDS-Unified Parkinson's Disease Rating Scale (p = 0.019). Patient saliva had elevated concentrations of amylase (127 vs 64 units/ml, p = 0.0005) and albumin (110 vs 47μg/ml, p = 0.0003) but not mucins.
  
  
  CONCLUSIONS
  This study suggests that the saliva of patients with PD is different in composition to that of healthy age-matched controls, supporting the notion that saliva may be a good candidate for biomarker discovery in PD. The specific differences suggest that major salivary glands and gingival crevicular fluid may both be sources of additional DJ-1 and protein in patient saliva.
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom; Mucosal & Salivary Biology Division, Floor 17 Tower Wing, King's College London Dental Institute, London, United Kingdom.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Masters
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom; Reta Lila Weston Institute of Neurological Studies, UCL Institute of Neurology, London, United Kingdom.
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Noyce
authors.affiliation: Reta Lila Weston Institute of Neurological Studies, UCL Institute of Neurology, London, United Kingdom.
authors.forename: Thomas T
authors.initials: TT
authors.lastname: Warner
authors.affiliation: Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
authors.forename: Gavin
authors.initials: G
authors.lastname: Giovannoni
authors.affiliation: Mucosal & Salivary Biology Division, Floor 17 Tower Wing, King's College London Dental Institute, London, United Kingdom. Electronic address: gordon.proctor@kcl.ac.uk.
authors.forename: Gordon B
authors.initials: GB
authors.lastname: Proctor
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000032:analysis*; D015153:Blotting, Western; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015513:Oncogene Proteins / Q000032:analysis* / Q000378:metabolism; D010300:Parkinson Disease / Q000378:metabolism*; D010865:Pilot Projects; D000071617:Protein Deglycase DJ-1; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000032:analysis* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; D015513:Oncogene Proteins; D012471:Salivary Proteins and Peptides; C105131:PARK7 protein, human; D000071617:Protein Deglycase DJ-1
keywords: Autonomic function; Biomarkers; DJ-1; Diagnostics; Parkinson's disease