To investigate the protective effects of astragalus polysaccharide (APS) on Pseudomonas aeruginosa induced pulmonary infection in rats.

Forty male SD rats were randomly divided into Control group, Model group and APS treatment group (Model+ 100 mg/kg APS (Model+ APS100) and Model+ 200 mg/kg APS (Model+ APS200). The rats were killed 24 hours after the model established. The wet/dry weight ratio (W/D ratio) of the lung tissue was measured. The number of total inflammatory cells and the levels of TNF-α and IL-1β in the bronchoalveolar lavage fluid were counted and measured by ELISA, respectively. The phosphorylation levels of p65 and IκBα protein in the lung tissue was measured by Western blot.

Compared with Control group, Pseudomonas aeruginosa significantly increased the W/D ratio of lung tissues (P<0.05), the number of inflammatory cells (P<0.05), the expression of TNF-α and IL-1 β (all P<0.05), and the phosphorylation of NF-κB p65/IκBα (all P<0.05). While APS treatment could significantly reverse the above changes (all P<0.05), and the effects of high dose APS was significantly stronger than that of low dose APS (all P<0.05).

It is effective for APS in treatment of lung infectious disease induced by Pseudomonas aeruginosa by inhibiting the activity of NF-κB p65/IκBα and reducing the production of TNF-α and IL-1β.