A murine model to study chronic airway fungal colonisation that recapitulates human disease

Aspergillus fumigatus is a ubiquitous environmental mould and a leading cause of chronic fungal-associated respiratory disease, yet the mechanisms by which persistent airway colonisation drives immune adaptation and lung pathology remain poorly understood. Progress in this area has been limited by the lack of in vivo models that recapitulate stable, non-invasive fungal persistence without immunosuppression. Here, we developed and optimised a murine model of chronic airway colonisation using agar bead-embedded A. fumigatus conidia delivered intratracheally. Embedding did not impair fungal germination or hyphal growth, and the agar matrix was immunologically inert, supporting its use as a neutral scaffold. This approach established stable fungal persistence in the airways for at least three weeks in immunocompetent mice without inducing invasive disease or systemic morbidity. Colonisation elicited a transient, airway-restricted innate immune response characterised by early neutrophil and monocyte recruitment and increased CXCL1, MIP-1, MIP-1{beta}, and TNF production, which resolved over time. Histopathological analysis revealed a progressive sequence of disease-relevant features, including initial immune containment, followed by mucus hypersecretion, and airway remodelling. At the adaptive level, persistent colonisation induced a dynamic T cell response that transitioned from an early polyfunctional profile to a sustained Th17-dominant phenotype. Importantly, application of this model in CFTR-deficient mice uncovered enhanced collagen deposition and fibrotic remodelling without altered fungal burden, demonstrating its utility in modelling disease-relevant outcomes in susceptible hosts. Together, this study establishes a robust and physiologically relevant platform for investigating host-fungal interactions during chronic airway colonisation. This model provides new opportunities to dissect mechanisms of immune adaptation, fungal persistence, and tissue remodelling, and to identify therapeutic strategies targeting chronic Aspergillus-associated lung disease.