Coptis chinensis polysaccharides dynamically influence the paracellular absorption pathway in the small intestine by modulating the intestinal mucosal immunity microenvironment

Traditional Chinese Medicine decoctions (TCMDs) can be used to prepare outstanding pharmaceutical preparations by the patient themselves. Small molecular active ingredients and macromolecular polysaccharides are inevitably co-existed in TCMDs. Different from the pharmacological synergies among small molecules, the macromolecular polysaccharides in TCMDs might contribute to disease treatment in several ways, although it is frequently overlooked.This study proposes that the oral bioavailability of the water-insoluble alkaloids of Coptis chinensis Franch. (Ranunculaceae) (C. chinensis) decoction may be attributed to the co-existing C. chinensis polysaccharides (CCPs) dynamically influencing the small intestine microenvironment and regulating the modulation of the paracellular absorption pathway.First, the effects of CCPs on the oral bioavailability of the main active ingredient of C. chinensis, berberine, were evaluated in vivo. Next, a series of in situ experimental models of intestinal perfusion and models of isolated jejunal mucosa, Caco-2 cell monolayer membranes, and microfold-like cells were established to assess the correlation among CCPs, intestinal mucosal immunity, and paracellular absorption in the small intestine.It was observed that CCPs could be endocytosed by the microfold cells on the surface of Peyer's patches, allowing CCPs to activate the lymphocytes, modulate the balance of Th1/Th2, control the secretion of immune effectors IFN-γ and IL-4, and finally regulate the tight junctions in the intestinal epithelial cells. This was a dynamic process with the movement of CCPs in the gastrointestinal tract that altered the flora distribution and functioning of the TLR/NF-κB signal pathway in the small intestine.The dynamical regulation of CCP on the immune microenvironment of small intestine is responsible for its promotion on the health controlling effects of C. chinensis in traditional dosage forms of decoction.