Sulfated Astragalus polysaccharide regulates the inflammatory reaction in LPS-infected broiler chicks

This study compared the anti-inflammatory activities of APS and SAPS in LPS-treated broiler chicks. The sulfated modification of these compounds was performed using the classic chlorosulfonic acid-pyridine method. On d 16, the birds were injected intramuscularly with 0.5 mL of either saline, APS (4 or 8 mg/kg BW) or SAPS (4 or 8 mg/kg BW) once a day for three successive days. On days 19 and 20, the birds were intraperitoneally injected with 0.5 mL of LPS (1 mg/kg BW). Saline was used as the blank control. The results showed that the LPS-treated birds exhibited higher expression of the pro-inflammatory cytokines IL-1β and IFN-γ and lower expression of the tight junction proteins ZO-2 and occludin in the jejunum. Administration of SAPS down-regulated the expression of jejunal TNF-α and IL-1β. In addition, the expression of both ZO-2 and occludin was higher in birds that received high doses of APS and SAPS. On the other hand, APS and SAPS had no effect on the condition of the immune system. The expression of TLR4 in the jejunum was lower in the low-dose SAPS group. Our findings suggest that SAPS is a more effective anti-inflammatory agent than APS in vivo.