Spore inhalation resulted in mild increase in IL4, IL5 and IL6, whereas culture filtrate induced a larger increaseTreatment with ET‐1 antagonist reduced extent of peribronchiolar inflammatory infiltration, reduced total BALF cell count and reduced collagen deposition. ET‐1 antagonist treatment also reduced AF‐induced IL4 and IL6ET‐1 was upregulated in response to aspergillus exposure, but protein levels remain unchanged in the lung. Culture filtrate resulted in enhanced endothelin protein in BALFCulture filtrate exposure showed increased airway remodelling in comparison to spore exposure. Here, IL4 is linked to atrial fibrillation.