The levels of IL-25 normalized to the total protein concentration were not significantly different between a subset of 24 NCs and 48 patients with IPF [8.39 (0.54–33.23) pg/μg vs. 0.0 (0.0–8.39) pg/μg, p = 0.432] (Additional file 2: Figure S1). Here, IL25 is linked to idiopathic pulmonary fibrosis.