title: Down-Regulation of Soluble α-Klotho is Associated with Reduction in Serum Irisin Levels in Chronic Obstructive Pulmonary Disease.
abstract: The klotho gene was originally identified as a putative aging-suppressor gene. Klotho-depleted mice display a shortened life span and exhibit a variety of premature aging-related phenotypes such as pulmonary emphysema and sarcopenia. This study was designed to determine the roles of secreted-type klotho protein on lung and skeletal muscle in chronic obstructive pulmonary disease (COPD).
  
  
  
  Serum α-klotho and irisin levels were assayed in 16 non-smokers, 13 smokers without COPD, and 24 smokers with COPD. Moreover, we examined correlations between soluble α-klotho levels and the results of lung function test, cardiopulmonary exercise test (CPET), and skeletal muscle function in smokers with COPD.
  
  
  
  Soluble α-klotho levels were significantly lower in smokers with COPD compared to non-smokers and smokers without COPD. In smokers with COPD, those levels did not significantly correlate with any parameters of lung function test. In CPET, peak VO2 significantly correlated with FEV1 (% predicted) (r = 0.76, p = 0.0003) and DLCO (% predicted) (r = 0.62, p = 0.003). In contrast, soluble α-klotho levels did not significantly correlate with peak VO2. Irisin levels were also significantly lower in smokers with COPD. Moreover, there was a significant correlation between soluble α-klotho and serum irisin levels (r = 0.61, p = 0.004).
  
  
  
  Our findings could provide a critical first step to understanding the impacts of soluble α-klotho on skeletal muscle in COPD and may lead to the identification of new molecular targets for the treatment of COPD.
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kureya
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan. kanazawa-h@med.osaka-cu.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kanazawa
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ijiri
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Tochino
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Asai
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, 1-4-3, Asahi-machi, Abeno-ku, Osaka, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Hirata
mesh_terms: D000368:Aged; D015992:Body Mass Index; D016022:Case-Control Studies; D015536:Down-Regulation; D015444:Exercise; D005353:Fibronectins / Q000097:blood*; D005541:Forced Expiratory Volume; D005966:Glucuronidase / Q000097:blood*; D006801:Humans; D000090265:Klotho Proteins; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D010101:Oxygen Consumption; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000503:physiopathology; D012907:Smoking / Q000097:blood* / Q000503:physiopathology
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins; D005966:Glucuronidase; D000090265:Klotho Proteins
keywords: Aging; Cardiopulmonary exercise test; Irisin; Skeletal muscle; α-Klotho