title: Serum interleukin 9 levels are increased in patients with systemic sclerosis: association with lower frequency and severity of pulmonary fibrosis.
abstract: OBJECTIVE
  To determine serum interleukin 9 (IL-9) levels and their clinical associations in patients with systemic sclerosis (SSc).
  
  
  METHODS
  Serum IL-9 levels were examined by ELISA in 71 patients with SSc, 15 with systemic lupus erythematosus (SLE), 15 with dermatomyositis (DM), 39 with atopic dermatitis, and 28 healthy individuals.
  
  
  RESULTS
  Serum IL-9 levels were significantly elevated in SSc patients (84.6 ± 76.0 pg/ml) compared with healthy individuals (40.4 ± 41.7 pg/ml; p < 0.001), and patients with SLE (50.7 ± 52.0 pg/ml; p < 0.05) or DM (50.6 ± 55.8 pg/ml; p < 0.05) or atopic dermatitis (41.8 ± 38.8 pg/ml; p < 0.001). Among SSc patients, there were no differences in serum IL-9 levels between those with limited cutaneous SSc and those with diffuse cutaneous SSc. Patients with SSc and raised IL-9 levels less often had pulmonary fibrosis and decreased percentage vital capacity than those with normal IL-9 levels. IL-9 levels were positively correlated with percentage vital capacity in patients with SSc.
  
  
  CONCLUSIONS
  Serum IL-9 level was increased in patients with SSc, and was associated with lower frequency and severity of pulmonary fibrosis in SSc. IL-9 could be a protective factor against the development of pulmonary fibrosis in this disease, and as such would be a possible therapeutic target.
authors.affiliation: Department of Dermatology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. yanabak-der@h.u-tokyo.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Yanaba
authors.forename: Ayumi
authors.initials: A
authors.lastname: Yoshizaki
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Asano
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kadono
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sato
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D016906:Interleukin-9 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology*; D012595:Scleroderma, Systemic / Q000150:complications / Q000276:immunology*; D012720:Severity of Illness Index
chemical_list: D016906:Interleukin-9