Supplementation with Astragalus polysaccharides alters Aeromonas-induced tissue-specific cellular immune response

Members of the genus Aeromonas inhabit various aquatic environments and are responsible for a number of intestinal and extra-intestinal infections in humans as well as other animals. Astragalus species are used in Chinese traditional medicine as antiperspirant, antihypertensive, diuretic and tonic treatments and have been used for treatment of patients with leukemia and uterine cancers. The present study was aimed to investigate immunomodulatory effect of Astragalus polysaccharides (APS) treatment on Aeromonas hydrophila-infected mice. The present data showed that APS-treatment ameliorated neutrophils phagocytic activity and reactive oxygen species (ROS) production in intestinal tissues of infected mice. Moreover, APS treatment induced a highly significantly (P < 0.001) increase in the number of CD4(+) T cells in the intestinal tissues and thymus, however, number of CD4(+) T cells in the spleens of infected mice not significantly changed with APS treatment. On the other hand, APS-treatment caused a very highly significant (P < 0.001) decrease in the number of CD8(+) T cells in the spleens and thymus of infected mice. In conclusion, the present data suggested that APS treatment reduced ROS production, downmodulated neutrophils activity, and increased CD4(+)/CD8(+) T cells ratio in A. hydrophila-infected mice.