Objectives: The increasing global burden of chronic pulmonary aspergillosis (CPA) is a health concern. CPA is associated with greater morbidity and mortality than invasive aspergillosis. Moreover, because of the frequency of relapse, anti-fungal treatment is often long-term leading to negative side effects and the development of resistance. The aim of this study was to investigate in host adaptation of Aspergillus fumigatus in CPA. 

Methods: Thirty Aspergillus fumigatus isolates were recovered from a CPA patient from 2008-2014. Whole genome sequencing was performed for 15 of the isolates to identify phylogenetic association between strains over time. An in vitro model using alveolar epithelial cells (A549) was used to describe fluctuations in the response of the lung epithelium to five of the A. fumigatus isolates recovered from the CPA patient compared to 3 A. fumigatus wild type strains (A1163, ATCC 90240 and ATCC 4664). A549 alveolar epithelial cells were exposed for 24 h to each of the strains and differences in epithelial cell detachment, fungal burdens and cytokine production (IL-8 and IFN) were evaluated. GraphPad Prism was used to interpret data and p values were calculated through One-way ANOVA test.

Results: A.s fumigatus strains isolated from the CPA patients were grouped into a common clade, although there was genetic variability within strains.  Epithelial cell desquamation of A549 cells exposed to the A. fumigatus-CPA strains was 20 % higher than controls (P < 0.0001). In accordance with that observation, fungal burdens were 5-10 times higher in A549 cells challenged with A. fumigatus CPA strains than controls (P < 0.05). Moreover, IL-8 and IFN concentrations in cell supernatants from A549 cells challenged with A. fumigatus- CPA strains were lower than in those challenged with A. fumigatus control strains (P < 0.01).

Conclusions:  Aspergillus fumigatus strains involved in a single case of CPA are phylogenetically associated. These strains were able to produce a higher percentage of epithelial cell damage than A. fumigatus strains used as controls. Therefore decreasing the ability of the epithelium to function as a physical barrier and, facilitating A. fumigatus growth and limiting the immune host response. Further research is needed to characterise the virulence properties of these strains.

3 / Aspergillus fumigatus strains are adapted to the lung environment in a case of chronic pulmonary aspergillosis