Isoprostane-8 in the exhaled breath condensate: Could it represent a noninvasive strategic tool for primary ciliary dyskinesia diagnosis and management?

Background and Objectives: Exhaled breath condensate (EBC) represents a potential diagnostic tool for Primary Ciliary Diskinesia (PCD). An increased oxidative stress is present in the airways of children affected and many neutrophil chemoattractants and markers of oxidative stress can be involved. The aim of the study is to evaluate leukotriene B4 (LTB-4), interleukin 8 (IL-8), 8-isoprostane (8-IP) concentration in PCD subjects, investigating their potential role as non-invasive markers of inflammation for the diagnosis and management of PCD. Methods: Cross-sectional study. 43 patients were enrolled in the study and divided in two groups: PCD (27) and healthy subjects (16). Physical examination, lung function test, nFeNO measurement and EBC collection were performed in all subjects. Results: PCD subjects showed an EBC 8-IP concentration significantly higher than the control group (median value: 11.9 pg/ml; IQR, 5.5-24.0 vs. median, 6.7 pg/ml; IQR, 2.5-11.3, p-value of Wilcoxon rank-sum test 0.0436). LTB4 EBC concentration did not differ between the two group (median, 4.3 pg/ml; IQR, 3.0-8.8 vs. 7.5 pg/ml; IQR, 3.0-9.5; P=0.4901). No significant correlation was found between FEV1 and EBC 8-IP (r=-0.10, P=0.6314) or LTB4 concentration (r=0.03, P=0.8888) in PCD subjects. No significant correlation was found between nFeNO and EBC 8-IP (r=-0.31, P=0.1385) or LTB4 (r=0.04, P=0.8565) in PCD subjects. Conclusions: EBC 8-IP levels are significantly increased in PCD subjects, highlighting the role of oxidative stress in airway inflammation. It could have a potential role as a non-invasive marker of inflammation for the diagnosis and management of PCD, although a therapeutic application of this evidence seems far.