Serum IGFBP2 as a marker of idiopathic pulmonary fibrosis

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder of unknown origin, which ultimately leads to death. Diagnosis is based on multidisciplinary consensus, but sensitive biomarkers are lacking. Several profibrotics proteins such as IGF and IGFBP seem to take part to the pathogenesis.

Aims of the study: The aim of this study was to evaluate surrogate new biomarkers by comparing their levels in serum, sputum and exhaled breath condensate (EBC) of patients with IPF, others fibrosis of known origin, COPD patients and healthy subjects.

Methods: Serum and induced sputum of 104 patients where analysed: idiopathic pulmonary fibrosis (n=15), non idiopathic pulmonary fibrosis (n=21) (NSIP, n=6; sarcoidosis, n=6; hypersensitivity pneumonitis, n=1; CTD, n=5; anthracosilicosis, n=1; other, n=2), COPD (n=26) and healthy subjects (n=42). Several biomarkers were assessed by ELISA (IGF1, IGF2, IGFBP1, IGFBP2, TGFβ, IL-8).

Results: Serum, but not sputum, IGFBP2 levels are significantly higher in the IPF group than in all the other groups (p<0.01). This is not linked with a high level of IGF1 or IGF2 meaning that this is not an IGF mediated observation. Serum IGFBP2 in IPF is not correlated with levels of IGFBP2 in induced sputum. Correlation study showed that the ratio IGF2/IGFBP2 in the serum of IPF patients where correlated with the severity of the disease assessed the forced vital capacity (r=0,8144; p<0,05).

Conclusion: Serum IGFBP2 could be a new interesting discriminant biomarker to identify and grade the severity of idiopathic pulmonary fibrosis.