Patients with chronic bronchiectasis experience in the course of their illness a vicious circle of inflammation, chronic infections and accompanying damage to the respiratory tract. In her work, Ilona Rosenboom, from the BREATH working group led by Prof. Burkhard Tümmler at the MHH, dealt with the infection part of the disease. She investigated the composition of the respiratory flora, the so-called airway metagenome, from samples taken from the patients of her cooperation partner, Prof. James Chalmers, at the University of Dundee in Scotland.  The airway metagenome depicts the whole genomic information of the microorganisms living in the lung. In order to characterize this symbiotic community of bacteria, viruses and fungi directly from its natural environment, a metagenomic pipeline was developed together with the Research Core Unit „Genomics“ at the MHH. DNA was isolated from sputum samples of patients and then read using sequencing and assigned to the relevant microorganisms using High-Performance-Computing (HPC).

The results showed that patients with bronchiectasis have a wide range of individual signatures, from diverse metagenomes comprised of dozens of commensal bacteria right up to monocultures of pathogens. Here, the most frequently found pathogens were Haemophilus influenzae and also Pseudomonas aeruginosa, known in mucoviscidosis (cf. www.breath-hannover.de/news-medien/news/news-detailseite.html. Samples with low diversity, i.e. a highly dominant pathogen, came typically from patients with a difficult disease progression. Those affected with a mild course of disease were overrepresented in the group of metagenomes without typical infection-associated germs. 

At the MHH, additional sputum samples were collected from healthy volunteers and sequenced in the same way, so that a comparison between sufferers and healthy volunteers could be made. Here it was noticeable that, in patients with bronchiectasis, health-associated bacteria, such as Neisseria subflava and Fusobacterium periodonticum were lacking, even if the samples did not exhibit any typical pathogens. Ms Rosenboom thus hypothesized that dysbiosis, an imbalance in the microbial ecosystem of the lung in patients with bronchiectasis, does not first occur due to the appearance of known pathogens, but already due to the lack of important commensal bacteria. „We now wish to check this hypothesis, in order to, if necessary, create future therapeutic possibilities for those affected“, says Rosenboom against the background that there is up to now in Germany no approved medication for bronchiectasis. 

We would like to express our sincere congratulations to Ms Rosenboom on being awarded this Poster Prize and hope that we may be able to report on more of her work in the future.

Text: BREATH/ AB/ IR

Photo: DZL Zentrale