title: Aberrant expression of cytokine interleukin 9 along with interleukin 4 and interferon γ in connective tissue disease-associated interstitial lung disease: association with severity of pulmonary fibrosis.
abstract: BACKGROUND
  Connective tissues diseases (CTDs) are a heterogeneous group of disorders that share certain clinical characteristics and disturbed immunoregulation. Interstitial lung diseases (ILDs), also known as diffuse parenchymal lung diseases, are among the most serious pulmonary complications associated with CTDs. Interleukin 9 (IL-9), IL-4 and interferon γ (IFN-γ) - cytokines with important roles in autoimmune disease - were studied in CTD patients and CTD-ILD patients.
  
  
  METHODS
  Sixty-one hospitalized untreated CTD patients were recruited, and 20 healthy volunteers were enrolled as controls. The 61 CTD patients were divided into a simple CTD group and a CTD-ILD group, and the plasma protein IL-9, IL-4 and IFN-γ levels were measured by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  The results indicate that the serum IL-9 levels were significantly higher in CTD-ILD and simple CTD patients than they were in healthy controls (each p < 0.05) and that the levels were elevated in CTD-ILD patients compared with simple CTD patients (p < 0.05). The IL-4 levels were higher in CTD-ILD patients than they were in the simple CTD patients (p < 0.05) and healthy controls (p < 0.01). In addition, the serum IL-9 levels were negatively correlated with the level of IFN-γ (r (2) = 0.34, p = 0.01), the estimated percentage of predicted forced vital capacity (FVC%) (r (2) = 0.36, p = 0.00) and the estimated percentage of predicted diffusing capacity (DLCO%) (r (2) = 0.27, p = 0.04) and were positively correlated with the IL-4 level (r (2) = 0.31, p = 0.01).
  
  
  CONCLUSIONS
  Interleukin-9 may play an important role in the pathogenesis of CTD and may contribute to the progression of interstitial lung injury in CTD patients.
authors.affiliation: Department of Nephrology, The Second Affiliated Hospital of Soochow University, Soochow, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Department of Nephrology, The Second Affiliated Hospital of Soochow University, Soochow, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Nephrology, The Second Affiliated Hospital of Soochow University, Soochow, China.
authors.forename: Han
authors.initials: H
authors.lastname: Ouyang
authors.affiliation: Department of Rheumatology, The Second Affiliated Hospital of Soochow University, Soochow, China.
authors.forename: Zhichun
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, Medical College of Soochow University, Soochow, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Nephrology, The Second Affiliated Hospital of Soochow University, Soochow, China.
authors.forename: Yongbing
authors.initials: Y
authors.lastname: Shi
keywords: connective tissues disease; interferon γ; interleukin 4; interleukin 9; interstitial lung disease