Abstract:

Objective    To investigate the effect of astragalus polysaccharides (APS) on expression of α-smooth muscle actin(α-SMA) in airway smooth muscle cells, and to investigate the possible mechanism of the effect. Methods   APS were isolated from Astragalus membranaceus. Cultivated human airway smooth muscle cells were divided into the APS groups in doses of 20, 100 and 500μg/mL, the control group, the lipopolysaccharide (LPS) group and Toll-like receptor 4(TLR4) antagonist group, and subsequently stimulated to express α-SMA by TGF-β. Expressions of α-SMA and mRNA were measured by immunocytochemistry, Western blot and RT-PCR. Results    Medium and high concentrations of APS inhibited expression of αSMA(P<0.01) and down-regulated the level of α-SMA mRNA(P<0.01), which could be partly reversed by the TLR4 antagonist (P<0.01). Conclusion    APS down-regulates expression of α-SMA stimulated by TGF-β in airway smooth muscle cells through TLR4,and has a potential role in the prevention and treatment of asthma.

Key words: Asthma； Actins; Muscle， smooth； Astragalus plant；  TLR4