Undaria pinnatifida extract attenuates combined allergic rhinitis and asthma syndrome by the modulation of epithelial cell dysfunction and oxidative stress

• UPE reduces OVA-specific immunoglobulin levels and improves early allergic symptoms in a mouse model of CARAS. • UPE suppresses Th2 cytokine expression and inflammatory cell accumulation in nasal and bronchoalveolar lavage fluid. • UPE protects airway epithelial barrier integrity by enhancing E-cadherin, ZO-1, and occludin expression and reducing IL-33. • UPE exerts antioxidant effects and inhibits NF-κB/MAPK signaling, suggesting a therapeutic potential for CARAS.