Effects of Laminaria japonica polysaccharides on airway inflammation of lungs in an asthma mouse model

Background: Asthma is a serious chronic inflammatory disease affecting 300 million people worldwide. This aim of this study to investigate the anti-inflammatory and anti-asthmatic effects of Laminaria japonica extract in the ovalbumin (OVA)-induced mouse asthma model. Methods: A mouse asthma model was established in SPF Kunming mice by OVA-sensitization followed by inhalation of aerosol allergen for two weeks. Laminaria japonica polysaccharides (LJPS) were given by gavage feeding at 50 mg/kg/day during OVA inhalation challenge period, and their effect on asthma was compared with the standard treatment of Budesonide inhalation. The total inflammatory cells and eosinophils in bronchoalveolar lavage fluid (BALF) were determined. Histopathological changes in lung tissue were studied and scored to determine the degree of inflammation. Levels of IL-12, IL-13, and TGF-beta 1 in BALF as well as serum levels of IgE were measured. Expressions of IL-12, IL-13, and TGF-beta 1 in lung tissues were assessed. Results: Highly inflammatory lungs infiltrated with significant increased eosinophils were observed in OVA-induced asthmatic mice. The OVA treated mice presented with a lower level of IL-12 and higher levels of IL-13 and TGF-beta 1 in BALF and lung tissues, as well as an increased level of the serum IgE. Treatment with LJPS (Group B) significantly decreased the numbers of eosinophils in the BALF (P< 0.05) and alleviated lung inflammation compared to the untreated asthma mice (Group A). It also reduced the serum IgE levels, increased expression of IL-12, and decreased the expression of IL-13 and TGF-beta 1 in BALF and lung (Both P < 0.05) compared with the group A. Conclusions: LJPS can significantly inhibit airway inflammation of asthmatic mice, adjust the balance of cytokines, and improve the pulmonary histopathological condition. Our data suggested that LJPS might be a potential therapeutic reagent for allergic asthma.