Signaling events driving Aspergillus fumigatus-induced eosinophil activation

Area of Science:

• Immunology
• Mycology
• Cell Biology

Background:

• Allergic bronchopulmonary aspergillosis (ABPA) is an incurable lung disease caused by Aspergillus fumigatus.
• ABPA involves a type 2 immune response with eosinophil infiltration in the lungs.
• Understanding eosinophil signaling in response to A. fumigatus is crucial for developing treatments.

Purpose of the Study:

• To investigate the signaling pathways utilized by eosinophils when interacting with Aspergillus fumigatus.
• To identify specific molecular targets within eosinophils that are activated by A. fumigatus.
• To explore potential therapeutic avenues for ABPA based on eosinophil signaling.

Main Methods:

• Utilized an in vitro coculture system of murine bone marrow-derived eosinophils and A. fumigatus conidia.
• Employed small-molecule inhibitors to probe eosinophil signaling modules.
• Assessed fungal metabolic activity, cytokine/chemokine secretion, ROS production, and surface receptor regulation.

Main Results:

• Eosinophils reduced fungal metabolic activity, a function not inhibited by targeting specific signaling modules.
• A. fumigatus-induced eosinophil secretion of Th2 cytokines/chemokines involved Src, PI3K, p38 MAPK, calcium, Akt, and PAD4.
• Src and PI3K kinases were critical for A. fumigatus-mediated ROS production and eosinophil activation, with their inhibitors preventing eosinophil activation.

Conclusions:

• Identified key signaling cascades, including Src and PI3K pathways, in eosinophil activation by A. fumigatus.
• These findings provide crucial insights into host-pathogen interactions in ABPA.
• Targeting identified signaling pathways, particularly Src and PI3K, presents promising therapeutic perspectives for ABPA.