Health-promoting effects of dietary polysaccharide extracted from Dendrobium aphyllum on mice colon, including microbiota and immune modulation

The health-promoting effects of a polysaccharide (DAP) purified from Dendrobium aphyllum, on mice colon were investigated. The results indicated that consumption of DAP facilitated the differentiation degree of CD4(+) T cells to Th-1, Th-17 and Treg cells; and depressed the differentiation degree to Th-2 cells, since DAP up-regulated IL-6 expression (from 1.08 +/- 0.24 to 3.40 +/- 0.36). Besides, oral administration of DAP reduced the gastrointestinal transit time from 255 +/- 1.21 to 164 +/- 0.46 min, decreased the pH from 6.70 +/- 0.27 to 5.54 +/- 0.31, improved faecal water-binding capability from 59.4% +/- 0.35 to 63.5% +/- 0.22. Additionally, the increase in four health-promoting short chain fatty acids were observed, which might result from the enrichment of the relative abundance of health-promoting microbiota genera, including Porphyromonadaceae and Ruminococcaceae. The DAP-induced up-regulation of the genus Erysipelotrichaceae might be related to the homeostasis in both Th-1/Th-2 and Treg/Th-17.