Astragalus polysaccharide reduces inflammatory response by decreasing permeability of LPS-infected Caco2 cells

As the major constituent of Radix Astragali, Astragalus polysaccharide (APS) is known for its anti-inflammation and immunomodulatory functions. The objective of this study was to investigate the effect of APS on inflammatory response and structural changes in lipopolysaccharide (LPS)-infected Caco2 cells. Caco2 cells were co-cultured with APS and LPS, with APS added after the addition of LPS (post-addition), before the addition of LPS (pre-addition), or simultaneously with the addition of LPS (simultaneous addition). The mRNA expression of inflammatory indicators and tight junctions was measured by RT-qPCR. Short circuit current (Isc) was recorded by an Ussing chamber system. Addition of APS significantly down-regulated the expression of TNF-α, IL-1β and IL-8 (P<0.05) and the Isc levels (P<0.05) of LPS-infected Caco2 cells for all three administration treatments. The minimum anti-inflammatory concentration of APS was 50, 100, and 100 μg/mL for pre-, post-, and simultaneous additions of APS, respectively. The mRNA expression of zonula occludens-1 (ZO-1) and occludin was significantly up-regulated for post- and pre-additions of APS, respectively (P<0.05). Results suggested that APS had anti-inflammatory and structure protective properties for LPS-infected Caco2 cells, and may be used as a preventative treatment for intestine cells.