Aspergillus fumigatus causes life-threatening infections in immunocompromised individuals. Neutrophils are essential for antifungal defence, but their function is often impaired in these patients. Granulocyte colony-stimulating factor (G-CSF) supports neutrophil survival and activation, yet systemic use can induce unwanted inflammation. The molecular mechanisms by which G-CSF enhances neutrophil function remain incompletely defined. To investigate whether ex vivo G-CSF-activated neutrophil transfer improves outcomes in invasive A. fumigatus infection and to explore the potential involvement of INHBA in regulating neutrophil dysfunction. Immunosuppressed mice were intranasally infected with A. fumigatus and subsequently received intravenous administration of G-CSF-activated neutrophils. Fungal burden, pulmonary inflammation, and cytokine expression were assessed. Transcriptomic and single-cell RNA sequencing analyses identified pathways regulated by G-CSF and INHBA . In vitro assays examined the impact of recombinant INHBA on neutrophil functions. Transfer of G-CSF-activated neutrophils significantly improved survival, reduced fungal load, and decreased lung inflammation. G-CSF downregulated INHBA , while patient neutrophils displayed elevated INHBA expression. Functional studies showed INHBA suppressed neutrophil chemotaxis, phagocytosis, and NET formation. G-CSF enhances neutrophil antifungal activity and is associated with modulation INHBA , suggesting a potential regulatory axis in neutrophil dysfunction during A. fumigatus infection. Ex vivo G-CSF-activated neutrophil transfer may represent a promising immunotherapeutic strategy for invasive aspergillosis. Author Summary Aspergillus fumigatus is a common fungus that can cause life-threatening infections in individuals with weakened immune systems, such as those undergoing chemotherapy or organ transplantation. Neutrophils, a type of white blood cell, are critical for fighting fungal infections. However, in many patients, these cells become functionally impaired, reducing the body’s ability to clear the infection. In this study, we explored how granulocyte colony-stimulating factor (G-CSF)—a naturally occurring molecule that promotes neutrophil survival and function—could be used to enhance neutrophil activity against A. fumigatus . Instead of administering G-CSF systemically, which can cause unwanted inflammation, we activated neutrophils outside the body and then reintroduced them into infected mice. These G-CSF-treated neutrophils significantly improved survival and reduced fungal burden in the lungs. Our analyses further suggested that G-CSF treatment is associated with reduced expression of INHBA, a molecule that may negatively regulate neutrophil function. We observed elevated INHBA levels in patient samples and found that INHBA could impair key neutrophil activities in vitro . While these findings indicate a potential role for INHBA in neutrophil dysfunction, further studies are required to define its precise mechanism of action. Overall, our work provides new insights into neutrophil regulation during fungal infection and supports the development of ex vivo G-CSF-activated neutrophil transfer as a potential therapeutic approach. • Granulocyte colony-stimulating factor (G-CSF) restores neutrophil function during Aspergillus fumigatus infection in immunocompromised hosts. • Transcriptomic analysis identifies INHBA as a potential immunoregulatory factor associated with neutrophil dysfunction during infection. • G-CSF treatment is associated with reduced INHBA expression, alongside improved fungal clearance, attenuated pulmonary inflammation, and enhanced survival. • Ex vivo G-CSF treatment of neutrophils enhances their anti-fungal capacity via increased ROS production, NET formation, and phagocytosis. • This study proposes a translational immunotherapy approach using G-CSF to potentiate host defence against invasive aspergillosis.
Zhang et al. (Fri,) studied this question.