COLLABORATION. During the European Respiratory Society Congress (ERS), a major event which recently concluded in Milan, several studies based on the PExA method were presented. PExA is a new method to monitor small airways by the measurement of droplets, i.e. particles, in exhaled air. Anna-Carin Olin, who leads the research group on breath analyses that has developed the PExA method, summarizes that the method had something of a breakthrough at the congress.
PExA (Particles in Exhaled Air) is a new method in which the research subject exhales into an instrument that measures and samples particles, that are formed when we breathe. The instrument was developed to detect and monitor pathological processes in the small airways, as in asthma and COPD.
At this year’s European Respiratory Society Congress, the ERS International Congress, which drew 24,000 attendees to Milan, a series of studies were presented in which PExA was used.
“It was something of a breakthrough for PExA. For the first time our results have reached a larger research audience, and there is great interest in our method, especially as there until now, were no non-invasive methods to achieve samples from the small airways, says Anna-Carin Olin, who is an adjunct professor of Occupational and Environmental Medicine (specialized in respiratory diseases), at Sahlgrenska Academy, and one of the developers of the PExA method.
The established method, currently used to investigate the small airways, is bronchoalveolar lavage (BAL), which involves putting patients through a disagreeable examination. In bronchoalveolar lavage, the upper airways are anesthetized and a tube is introduced into the airways. A fluid is injected into the lungs and then sucked back out, for further analyzes.
A new, non-invasive method
One of the PExA studies presented at the congress compares samples taken with PExA with those obtained through bronchoalveolar lavage. The study, presented by the pulmonary physician Annelie Behndig from Norrland University Hospital, showed a strong correlation between the established method and PExA. The study measured the amounts of the most common lung-specific protein, Surfactant Protein A, and albumin, both in fluid taken using BAL and samples taken from exhaled air using the PExA method, from the same subject. The levels of Surfactant Protein A in BAL and in PExA samples were shown to correlate strongly and significantly. There was however no correlation with samples from the upper airways, sampled by a method known as “bronchial washing”. This confirms that PExA samples really do come from the peripheral airways.
Asthma-specific proteins
Another study presented at the congress showed that it is possible to identify a broad protein profile in individual PExA samples from the small airways, with high reproducibility. “This might have been the biggest PExA news of the congress. It’s possible to identify more than 145 different proteins in a single individual, by applying an extremely sensitive method of analysis” explains Anna-Carin Olin.
The results were presented by Jörgen Östling, a researcher at AstraZeneca. The study, a collaboration between AstraZeneca and the Department of Occupational and Environmental Medicine at the University of Gothenburg, also showed that the pattern formed by 57 of these proteins could distinguish subjects with asthma from healthy controls. “Many of the identified proteins have important functions pertaining to oxidative stress and the immune system, further supporting the usefulness of the PExA samples to monitor respiratory disease. One unexpected, but very interesting observation was that the abundance of many of these proteins changes with age, and that the aging process seemed to be accelerated in people with asthma,” says Anna-Carin Olin.
A valuable method for pulmonary research
Two other studies showed that the lipid composition in the PExA-samples was also altered – not only in patients with asthma, but also in smokers and subjects with COPD. The latter study was presented by Emilia Viklund, a PhD student in the Department of Occupational and Environmental Medicine at GU. The discovery of an altered lipid profile in smokers and people with COPD is especially interesting, because there are still no known early markers for COPD.
“These findings demonstrate that the PExA method has a strong potential to become a valuable tool in continued pulmonary research, especially as the method is non-invasive and can be used to follow disease processes over time. We have a very exciting time ahead of us, as more research teams will be able to use the method to answer many new research questions, but it is also important to follow up on the current findings, which need to be confirmed in larger studies. We are still in a very early phase of development,” elucidates Anna-Carin Olin.
TEXT: ELIN LINDSTRÖM CLAESSEN
PHOTOS FROM THE CONFERENCE BY ERIK EKBO.
