title: Pneumocyte biomarkers KL-6 and surfactant protein D reflect the distinct findings of high-resolution computed tomography in nonspecific interstitial pneumonia.
abstract: BACKGROUND
  Serum levels of pneumocyte biomarkers KL-6 and surfactant protein D (SP-D) are useful diagnostic markers for interstitial lung diseases. However, associations of serum KL-6 and SP-D with radiologic findings in nonspecific interstitial pneumonia (NSIP) remain unclear.
  
  
  OBJECTIVE
  To determine whether serum levels of KL-6 and SP-D reflect fibrotic and/or inflammatory processes in NSIP, we investigated the correlation between high-resolution computed tomography (HRCT) findings and serum KL-6 and SP-D levels.
  
  
  METHODS
  Serum levels of KL-6 and SP-D were measured in 21 patients with biopsy-confirmed NSIP. The radiographic extent of 6 HRCT patterns and total HRCT score, defined as the scored fibrotic index, were assessed. Changes in the levels of serum markers and CT findings during follow-up were also monitored.
  
  
  RESULTS
  Serum levels of KL-6 in NSIP positively correlated with the total HRCT score and overall extent of interstitial disease. Serum levels of SP-D in NSIP showed a positive correlation with the area of ground-glass attenuation without traction bronchiectasis and the inflammatory CT pattern, but the levels were inversely correlated with the area of ground-glass attenuation with traction bronchiectasis and the fibrotic CT pattern. The follow-up CT and serum marker changes after treatment showed that percent change of disease extent was reflected in both markers, especially KL-6. Further, the decreased fibrotic pattern correlated with both biomarkers.
  
  
  CONCLUSIONS
  The results indicate that serum levels of KL-6 in NSIP reflect the overall extent of interstitial lesions, which include both inflammatory and fibrotic lesions, while the levels of SP-D mainly reflect the extent of inflammatory lesions.
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan. ichiyasu @ kumamoto-u.ac.jp
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ichiyasu
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ichikado
authors.forename: Akihisa
authors.initials: A
authors.lastname: Yamashita
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Iyonaga
authors.forename: Osamu
authors.initials: O
authors.lastname: Sakamoto
authors.forename: Moritaka
authors.initials: M
authors.lastname: Suga
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Kohrogi
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001987:Bronchiectasis / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000097:blood* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; C060192:MUC1 protein, human; D018396:Mucin-1; D037663:Pulmonary Surfactant-Associated Protein D