title: The elevation of serum napsin A in idiopathic pulmonary fibrosis, compared with KL-6, surfactant protein-A and surfactant protein-D.
abstract: BACKGROUND
  Napsin A, an aspartic protease, is mainly expressed in alveolar type-II cells and renal proximal tubules and is a putative immunohistochemical marker for pulmonary adenocarcinomas. This study sought to determine whether napsin A could be measured in the serum to evaluate its relationship to idiopathic pulmonary fibrosis (IPF) and determine whether renal dysfunction might affect serum napsin A levels.
  
  
  METHODS
  Serum levels of napsin A were measured in 20 patients with IPF, 34 patients with lung primary adenocarcinoma, 12 patients with kidney diseases, and 20 healthy volunteers. Surfactant protein (SP)-A, SP-D, and Krebs von den Lungen-6 (KL-6) levels in serum and pulmonary function tests were also evaluated in IPF patients.
  
  
  RESULTS
  Circulating levels of napsin A were increased in patients with IPF, as compared with healthy controls, and they correlated with the severity of disease. Moreover, the serum napsin A levels were not elevated in patients with pulmonary adenocarcinoma or renal dysfunction. The distinguishing point between IPF and the controls was that the area under the receiver operating characteristic curve (ROC) of napsin A was larger than that of KL-6, SP-A, or SP-D.
  
  
  CONCLUSIONS
  These findings suggest that serum napsin A may be a candidate biomarker for IPF.
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Sakuragaoka, Kagoshima, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Samukawa
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uto
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yanagi
authors.forename: Go
authors.initials: G
authors.lastname: Tsukuya
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nosaki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Maeda
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirano
authors.forename: Hirohito
authors.initials: H
authors.lastname: Tsubouchi
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000503:physiopathology; D000328:Adult; D000368:Aged; D016282:Aspartic Acid Endopeptidases / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000097:blood* / Q000503:physiopathology; D007668:Kidney / Q000503:physiopathology; D007674:Kidney Diseases / Q000097:blood / Q000503:physiopathology; D008168:Lung / Q000503:physiopathology; D008175:Lung Neoplasms / Q000097:blood / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood*; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood*; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D012129:Respiratory Function Tests
chemical_list: D015415:Biomarkers; C060192:MUC1 protein, human; D018396:Mucin-1; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D016282:Aspartic Acid Endopeptidases; C498549:NAPSA protein, human