Optimising ovalbumin (OVA) sensitisation protocols for asthma modelling: frequency and duration effects on lung biomarkers

Abstract

Ovalbumin (OVA)-sensitised rodent models are widely used to study allergic asthma; however, protocol variations may compromise translational relevance. This study investigates the effects of OVA sensitisation frequency and duration on oxidative stress, inflammation, and lung histopathology. Forty two female Wistar rats were randomly assigned to six groups. Groups were sensitised with OVA on different schedules (days 1 and 7; days 1, 7, and 14) with or without a subsequent 1% OVA aerosol challenge twice weekly for 28 days. Lung homogenates were assayed for malondialdehyde, superoxide dismutase, catalase, glutathione peroxidase, and total protein. Cytokine levels (IgE, IL-1β, IL-4, IL-6) were measured, and histopathology was assessed via H&E staining. The results showed no statistically significant differences were observed in lung tissue MDA, SOD, CAT, GPx, or total protein across groups (p>0.05). IgE and IL-6 levels showed no significant variation, while IL-1β and IL-4 levels decreased significantly in the group sensitised on days 1, 7, and 14 with challenge (p < 0.05). Histological analysis revealed progressive lung tissue damage, including alveolar epithelial destruction,
mucus-filled bronchi, perivascular fibrosis, and pulmonary artery hypertrophy, particularly in groups with increased sensitisation frequency and aerosol challenge. In Conclusion, although repeated OVA sensitisation and challenge induced marked histopathological changes characteristic of asthma, they did not elicit significant oxidative or classical Th2 immune biomarker responses. These findings suggest that protocol optimisation is needed to achieve comprehensive immunopathological mimicry of human asthma in Wistar rat animal models.