Late Breaking Abstract - Exploring particles from exhaled air as a new source for protein biomarkers from the airways

Although highly desired, there are currently no non-invasive methods to collect samples from distal airways for robust biomarker analysis. Breath contains particles which are formed in small airways when the lining fluid bursts during inhalation. These particles can be collected by impaction technology (PExA AB). We have identified a method that allows us to examine the protein content of these particles and we have addressed the following questions: - How many different proteins can be detected and accurately quantified? - Are the detected proteins relevant in respiratory disease? - Is it possible to identify protein signatures that can be used to sub-phenotype asthma? Method: 10 healthy controls and 20 subjects with asthma, of whom 10 with normal small airway function as defined by lung-clearance index (LCI), were included. Particles in exhaled air samples were analyzed using a proteomic platform assessing the relative quantity of 1310 different proteins (SomaLogic, Inc). Results: Up to 207 different proteins could be detected in a robust way. The relative quantity of 36 proteins, including several S100 proteins and proteins involved in coagulation and antioxidant response, were different in asthma as compared to controls (p Conclusion: Our findings demonstrate how protein biomarkers originating from the distal airway can be assessed in a non-invasive way. The obtained protein profile unique to a subgroup within asthma suggest that the method captures pathobiologically relevant proteins and hold potential to boost development of Precision Medicines in respiratory disease.