title: Surfactant protein D and KL-6 serum levels in systemic sclerosis: correlation with lung and systemic involvement.
abstract: OBJECTIVE
  The aim of this study was to investigate the relationship between SP-D and KL-6 serum concentrations and the extent of interstitial lung involvement, as measured by a quantitative HRCT score and the functional impairment, in patients with systemic sclerosis (SSc). Moreover we analysed the association between these lung-specific biomarkers and skin involvement, anti-Scl-70 antibody titres and an index of disease activity.
  
  
  METHODS
  Serum SP-D, KL-6 and anti-Scl-70 concentrations were determined by ELISA in 25 SSc patients. Disease activity and lung function parameters were assessed, and the extent of ILD was measured by a HRCT score.
  
  
  RESULTS
  SP-D and KL-6 concentrations were higher in patients with SSc and lung fibrosis than in healthy controls. KL-6 correlated positively with the HRCT-fibrosis score (r=0.68, p<0.001), SP-D showed a weaker correlation (r=0.44, p=0.025). Increased KL-6 concentrations were associated with decreased DLCO and decreased FVC in SSc patients, SP-D showed no association. Furthermore KL-6, but not SP-D, showed a strong association with skin involvement as expressed by the modified Rodnan skin score (r=0.71, p<0.0001) and a disease activity index (r=0.73, p<0.0001).
  
  
  CONCLUSIONS
  KL-6 is more strongly associated than SP-D with the HRCT-fibrosis score, and, different from SP-D, it correlates with skin involvement and disease activity. We suggest that KL-6 may be a useful biomarker in the assessment of scleroderma patients.
authors.affiliation: Department of Biomedical and Surgical Sciences, Respiratory Physiopathology, University of Verona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Bonella
authors.forename: A
authors.initials: A
authors.lastname: Volpe
authors.forename: P
authors.initials: P
authors.lastname: Caramaschi
authors.forename: C
authors.initials: C
authors.lastname: Nava
authors.forename: P
authors.initials: P
authors.lastname: Ferrari
authors.forename: K
authors.initials: K
authors.lastname: Schenk
authors.forename: S
authors.initials: S
authors.lastname: Ohshimo
authors.forename: U
authors.initials: U
authors.lastname: Costabel
authors.forename: M
authors.initials: M
authors.lastname: Ferrari
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D011379:Prognosis; D011658:Pulmonary Fibrosis / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D012129:Respiratory Function Tests; D012595:Scleroderma, Systemic / Q000097:blood* / Q000150:complications; D012720:Severity of Illness Index
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; C060192:MUC1 protein, human; D018396:Mucin-1; D037663:Pulmonary Surfactant-Associated Protein D