Fucoidan attenuates airway remodeling in asthmatic mice

Airway remodeling is a pathological hallmark of asthma that is difficult to reverse and effective therapeutic interventions remain limited. The present study investigated whether fucoidan, a natural sulfated polysaccharide derived from seaweed, attenuates airway remodeling in ovalbumin (OVA)-induced asthmatic mice. In total, 40 female Kunming mice were randomly assigned to four groups (n=10/group): Asthma, budesonide, fucoidan and control. Asthma was induced by OVA sensitization and challenge. Budesonide was administered via nebulization, while fucoidan was given by oral gavage prior to OVA challenge. Bronchoalveolar lavage fluid was collected for total and differential cell count and levels of interleukin-21, thymic stromal lymphopoietin, α-smooth muscle actin and collagen I in the lavage fluid were measured by ELISA. Lung sections were evaluated by hematoxylin and eosin staining for histopathological changes and immunohistochemistry for protein expression. Fucoidan significantly alleviated asthma-like behavior, including scratching, shortness of breath and restlessness, and reduced total cells, neutrophils, lymphocytes and eosinophils in bronchoalveolar lavage fluid compared with the OVA group (P<0.05). Fucoidan decreased the elevated levels of interleukin-21, thymic stromal lymphopoietin, α-smooth muscle actin and collagen I (P<0.05), with effects comparable with those of budesonide (P>0.05). Histological examination revealed that fucoidan attenuated peribronchial inflammatory infiltration, bronchial wall thickening and luminal narrowing. Immunohistochemical analysis confirmed that fucoidan suppressed the expression of IL-21, thymic stromal lymphopoietin, α-smooth muscle actin and collagen I in lung tissue, as reflected by significantly decreased integrated optical density values relative to the model group (P<0.05). Collectively, these findings indicated that fucoidan attenuates airway remodeling in asthmatic mice, which may be associated with downregulation of interleukin-21 and thymic stromal lymphopoietin. Although the underlying mechanisms and clinical applicability require validation, the present results suggest that fucoidan merits investigation as a potential candidate for asthma therapy.