Employing various human Macrophage in vitro models to determine early key factors in successful defense upon Aspergillus fumigatus encounter

Aspergillus fumigatus, a saprotrophic mold commonly found in soil on decaying matter, propagates via spore formation and aerial distribution. Inhalation of these spores by immunocompromised patients can cause life-threatening invasive aspergillosis. Healthy individuals also inhale hundreds to thousands of spores daily but still maintain lung homeostasis. The mechanisms determining whether this airborne pathogen can be contained or will invade the alveolar epithelia to cause infection remains elusive.

We aim to investigate early decision points in alveolar macrophages upon initial encounter with A. fumigatus by deploying various human macrophage (MΦ) populations.

We utilized the recently published AML cell model [1] and screened it for primary alveolar MΦ markers. Likewise, we stimulated these cells with A. fumigatus, employing GM-CSF MΦs as controls and ELISA as well as qPCR as readouts. For further comparison, AML cells and GM-CSF MΦs were challenged with A. fumigatus conidia at different time intervals, followed by dual RNA-sequencing. Transcriptomic profiles were evaluated comparing shared and characteristic expression patterns of MΦs specific to defined A. fumigatus morphotypes. Likewise, gene expression of A. fumigatus confronted with different MΦ populations was analyzed. In addition, we compare these MΦ profiles with pre-existing gene expression profiles of other myeloid immune cells challenged with A. fumigatus based on archived GEO data sets. This will reveal shared but also population-specific profiles as well as characteristic A. fumigatus counter defense strategies. Furthermore, we employ the FLARE conidia model [2] in flow cytometry and Single-Cell analysis to decipher molecular differences in phagocytic and killing ability of the MΦ types.

We evaluate the AML model for infection with the fungal pathogen A. fumigatus and compare it with GM-CSF and primary MΦs. Through this, we will be able to identify initial key factors of MΦs to prevent lung infection by A. fumigatus.

[1] Pahari et al. mBio vol. 14,4 (2023): e0083423. doi:10.1128/mbio.00834-23

[2] Jhingran et al. Cell Reports vol. 2,6 (2012): 1762-73. doi:10.1016/j.celrep.2012.10.026