Orally administered fisetin as an immuno-modulatory and therapeutic agent in a mouse model of chronic allergic airway disease

Introduction: Allergic asthma is a prevalent disorder, in which eosinophilic inflammation is involved in the lungs. Asthma affects people all over the world, regardless of the country's level of development. Chronic allergen-induced fibrotic damage of the lungs is stimulated in 55 days, which results in significant tissue destruction constitutive to pulmonary tissues, in addition to extensive oxidative & inflammation-induced damage of small and large airways. To date, there is no cure for asthma, and symptoms are controlled using corticosteroids, which may cause systemic side effects. Flavonoids, like fisetin, are a class of secondary metabolites produced by plants, which are known to have numerous beneficial effects. Previous report demonstrated that fisetin has beneficial effects against various diseases such as cancers, tumors, diabetes, and alcohol-induced liver injury. Methods: In the present study, chronic allergic disease (asthma) was developed in C57BL/6J mice, using intraperitoneal injection of ovalbumin for 54 days together with orally administered fisetin as a treatment strategy. Fisetin was administered 1 hour before intratracheal treatment. On day 55, treated animals were sacrificed, and tissues were collected for various assays. Results: Fisetin was found to reduce the symptoms of asthma significantly. Reduction in total cell infiltration, eosinophil count, and the levels of serum IgE were observed. There was a down regulation in CD3(+) CD4(+) T-H cells, and a decrease in the deposition of collagen in the lung and airways. Conclusion: From these observations, we conclude that fisetin is effective in the treatment of asthma, and a pathway by which fisetin acts was hypothesized.