Demonstration of the effective intestinal immunity activity of a high branched rhamnogalacturonan-I type pectin from wolfberry via exploration its interaction with colon biological and mechanical barrier.

The colon immune activity of high branched rhamnogalacturonan-I type pectin from Lycium barbarum fruit (LBP-P4) was unclear. This study comparatively investigated the colon immunity activity of LBP-P4 and inulin and explored its mechanism via simulated colon biological and mechanical barriers models. LBP-P4 could be slowly degraded and utilized by intestinal microorganisms with degradation rate of 88.88 %. Meanwhile, LBP-P4 increased the relative abundance of Bifidobacterium, especially Bifidobacterium longum subsp. longum, which was confirmed by single Bifidobacterium fermentation. In the normal colon mechanical barrier coupled with macrophage model, the colonic metabolites of LBP-P4 enhanced macrophage viability and phagocytic ability. In the damaged colon mechanical barrier coupled with macrophage model, the colonic metabolites of LBP-P4 enhanced mechanical barrier integrity, reduced the production of NO and IL-6 and improved macrophage viability and phagocytic ability. The colon immunity activity of LBP-P4 was stronger than that of inulin, which was because the contents of immunity related metabolites i.e. short chain fatty acids and tryptophan metabolites, were significantly higher (about 1-3 fold) in LBP-P4 group than those in inulin group. Our findings provided new insights into the probiotic and intestinal immunity function of LBP-P4 and offered theoretical basis for the development of functional products of LBP-P4.