The magnitude of airway remodelling is not altered by distinct allergic inflammatory responses in BALB/c vs C57BL/6 mice but matrix composition differs

Abstract

AbstractAllergic airway inflammation is heterogenous with variability in immune phenotypes observed across asthmatic patients. Inflammation has been thought to directly contribute to airway remodelling in asthma, but clinical data suggests that neutralising type 2 cytokines does not necessarily alter disease pathogenesis. Here, we utilised C57BL/6 and BALB/c mice to investigate the development of allergic airway inflammation and remodelling. Exposure to an allergen cocktail for up to 8 weeks led to type 2 and type 17 inflammation, characterized by airway eosinophilia and neutrophilia and increased expression of chitinase-like proteins in both C75BL/6 and BALB/c mice. However, BALB/c mice developed much greater inflammatory responses than C57BL/6 mice, effects possibly explained by a failure to induce pathways that regulate and maintain T cell activation in C57BL/6 mice, as shown by whole lung RNA transcript analysis. Allergen administration resulted in a similar degree of airway remodelling between mouse strains but with differences in collagen subtype composition. Increased collagen III was observed around the airways of C57BL/6 but not BALB/c mice while allergen-induced loss of basement membrane collagen IV was only observed in BALB/c mice. This study highlights a model of type 2/type 17 airway inflammation in mice whereby development of airway remodelling can occur in both BALB/c and C57BL/6 mice despite differences in immune response dynamics between strains. Importantly, compositional changes in the ECM between genetic strains of mice may help us better understand the relationships between lung function, remodelling and airway inflammation.