Abstract Background Damaged alveolar epithelial cells and activated fibroblasts are major sources of IL-11 in fibrotic lung diseases. Interleukin (IL)-11 is suggested to play a key role in lung fibrosis by hindering the repair of lung tissue, which leads to fibroblast activation and further fibrosis1. Detecting IL-11 can be challenging due to its very low abundance. Aims To evaluate IL-11 levels in bronchoalveolar lavage samples (BAL) from patients with idiopathic pulmonary fibrosis (IPF) and compare with control subjects (C) and patients with nonspecific interstitial pneumonia (NSIP). Methods Free IL-11 (fIL-11) levels were analyzed from frozen diagnostic BAL samples of patients with IPF, NSIP and from control subjects, defined as individuals without respiratory diseases. A highly sensitive ELISA was developed with a lower limit of quantification of 1,1 fg/mL. The assay was validated retrospectively using the fit-for-purpose principle, including the determination of several parameters such as precision and selectivity. Statistical differences between groups were analyzed by ANOVA with subsequent Kruskal-Wallis test. P-values less than 0.05 were considered statistically significant. Results 74 consecutive subjects (40 IPF, 21 NSIP and 13 C) who underwent a diagnostic BAL from 2014 to 2017 were studied. BAL fIL-11 levels are significantly (p 0.0001) elevated in patients with IPF (51.0 ± 33.4 fg/mL) compared to patients with NSIP (5.0 ± 3.7 fg/mL) and control subjects (0.6 ± 0.0 fg/mL), (Mean value ± SEM). No differences were seen according to gender and age. Conclusion High fIL-11 levels in the BAL of patients with IPF might warrant clinical exploration of an anti-IL-11 therapeutic in this patient population. This abstract is funded by: Boehringer Ingelheim
Bonella et al. (Fri,) studied this question.