Protective effect of Astragalus polysaccharides on ATP binding cassette transporter A1 in THP-1 derived foam cells exposed to tumor necrosis factor-alpha.

Astragalus polysaccharide (APS), the main extract from the traditional Chinese medicinal herb Astragalus membranaceus, has been reported to benefit the treatment of immune-inflammatory diseases and metabolic disorders. In atherosclerotic plaques, proinflammatory cytokines exert adverse effects on lipids thereby aggravating atherosclerosis. Recent evidence shows that tumor necrosis factor-alpha (TNF-alpha) can down-regulate the expression of ATP-binding cassette transporter A1 (ABCA1), which plays a vital role in reverse cholesterol transport and determines the process of atherosclerosis. In the present study, the effects of APS on ABCA1 expression, cholesterol effluent rate and total cholesterol content of THP-1 derived foam cells exposed to TNF-alpha were investigated. Compared with the foam cells exposed to TNF-alpha, ABCA1 expression was promoted in the presence of APS. Consequently the cholesterol effluent rate increased and the total cholesterol content decreased significantly. TNF-alpha could enhance the activity of nuclear factor-kappa B (NF-kappaB) in the foam cells. This effect could be attenuated by APS. These findings suggest that APS could protect ABCA1 against the lesion of TNF-alpha in THP-1 derived foam cells, which may contribute to its antiatherosclerotic properties.