IFN-γ shapes neutrophil function and lung host defense against Aspergillus fumigatus 2220821

Introduction Aspergillus fumigatus (Af), a ubiquitous airborne fungus, causes >90% of invasive aspergillosis (IA). While triazole antifungals are standard therapy, rising resistance underscores the need to define host-protective mechanisms. Neutrophils are essential for antifungal defense, and we identified them as the predominant source of interferon-γ (IFN-γ) during pulmonary Af infection. Loss of IFN-γ signaling increases mortality and reduces neutrophil effector responses, underscoring its role in host defense. Methods scRNA-seq of lung neutrophils revealed enrichment of immature subsets in Af-infected WT mice versus naïve controls, consistent with infection-driven granulopoiesis. To test whether neutrophil-derived IFN-γ integrates lung cues to influence neutrophil development, we are analyzing Af-infected versus naïve Mrp8CreStat1fl/fl and Mrp8CreIfnlr1fl/fl mice, combining bone marrow and lung analyses with flow maturation markers. In parallel, to capture IFN-γ activity beyond neutrophils, we are performing whole-lung scRNA-seq of Af-infected WT and IFNLR-deficient mice, encompassing both immune (CD45+) and structural (CD45⁻) cells. Ongoing confocal microscopy with labeled spores, EpCAM, and Ly6G further examines neutrophil—epithelial interactions. Results Bulk RNA-seq of lung neutrophils showed induction of interferon-stimulated genes (Oasl1, Ifit1, Rtp4, Zbp1, Cmpk2) in WT mice after Af infection, which was reduced in IFNLR-/- and IFNAR-/-IFNLR-/- mice. RT-qPCR confirmed these findings. Preliminary analyses of conditional knockouts suggest context-dependent contributions of IFN-γ to neutrophil maturation and effector responses. Conclusion Neutrophil-derived IFN-γ is a critical regulator of antifungal defense. Current and future studies will define its dual role: (1) controlling neutrophil development through lung—bone marrow axes, and (2) shaping multicellular pulmonary immunity by acting on immune and structural compartments during Af infection. Funding Source N/A Topic Categories Innate Immune Responses and Host Defense: Cellular Mechanisms (INC)