Screening Potential Biomarkers for Idiopathic Pulmonary Fibrosis in Bronchoalveolar Lavage Fluid

IPF is the most lethal form of interstitial lung disease. Diagnosis is based on multidisciplinary consensus, but sensitive biomarkers are lacking. In this study Vitamin D, Krebs von den Lungen-6 (KL-6), C-peptide, Immunoglobulin E (IgE) and a fragment of Cytokeratin 19 (CYFRA21-1) were screened as possible biomarkers for IPF. Using the Lumipulse ® G1200 (Fujirebio, Ghent, Belgium) the analytes were measured in BAL samples of 83 IPF patients and 10 controls. The mean follow-up of the IPF patients was 930 days and during this timeframe 25 patients died. Lung function (FVC, FEV1, DLCO, TLC) was evaluated at the time of BAL and around 6 months after BAL sampling in the IPF patients. Survival analysis was performed for IPF patients with high concentrations of the analytes (> median concentration) and IPF patients with low concentrations (≤ median concentration). Vitamin D was not measurable and KL-6 did not significantly differ between the IPF patients and controls. However, there was a significant increase in the levels of C-peptide (p=0.0015), IgE (p=0.0006) and CYFRA21-1 (p=0.0004) in the IPF patients compared to the controls. IPF patients with high levels (> 1.2 ng/ml) of CYFRA21-1 had a worse survival than patients with lower levels of CYFRA21-1 (p=0.045). The other analytes did not correlate with the survival of the IPF patients. None of the examined analytes were predictive for the lung function evolution in the first 6 months. Of the tested analytes in BAL, CYFRA21-1 correlated with survival and therefore deserves more attention as a possible biomarker for IPF. But more validation and analysis is requested including serum measurement, other ILD types and multivariate analysis.