FeNO and Blood Eosinophil Counts in Idiopathic Pulmonary Fibrosis: Potential Biomarkers of Response to Nintedanib

In the bronchoalveolar lavage (BAL) of IPF patients, eosinophilia greater than 10% is observed. Additionally, nitric oxide (NO) plays a crucial role in the aberrant angiogenesis process in fibrotic lungs. Our aim is to evaluate the role of blood eosinophil counts (BECs) and FeNO as potential biomarkers for IPF. A total of 38 IPF patients (mean age 75.5 ± 6.7 years) followed at the University of Ferrara was enrolled. We monitored BECs and FeNO at baseline (T0, time of diagnosis and initiation of antifibrotic therapy) and after 12 months (T12) of treatment. We found higher BECs in patients on Nintedanib treatment (0.54 ± 0.13 x10³/mcrl) compared to those on Pirfenidone (0.13 ± 0.10 x10³/mcrl) or not on treatment (0.02 ± 0.01 x10³/mcrl). We also measured exhaled nitric oxide (FeNO) after 12 months of antifibrotic therapy and observed a higher FeNO concentration in patients treated with Nintedanib (29.42 ± 2.99 ppb) compared to the group on Pirfenidone therapy (20.8 ± 20.5 ppb). We propose for the first time in the literature the role of eosinophils and FeNO as potential biomarkers of response to antifibrotic therapy (Nintedanib). This needs to be further demonstrated in a larger population of patients.