Rhamnogalacturonan, a chemically-defined polysaccharide, improves intestinal barrier function in DSS-induced colitis in mice and human Caco-2 cells

Abstract

Natural polysaccharides have emerged as an important class of bioactive compounds due their beneficial biological effects. Here we investigated the protective and healing effects of rhamnogalacturonan (RGal) isolated from Acmella oleracea (L.) R.K. Jansen leaves in an experimental model of intestinal inflammation in mice and in heterogeneous human epithelial colorectal adenocarcinoma cells (Caco-2). The findings demonstrated that RGal treatment for 7 days reduced the severity of DSS-induced colitis by protecting mice from weight loss, macroscopic damage and reduction of colon length. When compared to the DSS group, RGal also protected the colon epithelium and promoted the maintenance of mucosal enterocytes and mucus secreting goblet cells, in addition to conserving collagen homeostasis and increasing cell proliferation. In an in vitro barrier function assay, RGal reduced the cellular permeability after exposure to IL-1β, while decreasing IL-8 secretion and claudin-1 expression and preserving the distribution of occludin. Furthermore, we also observed that RGal accelerated the wound healing in Caco-2 epithelial cell line. In conclusion, RGal ameliorates intestinal barrier function in vivo and in vitro and may represent an attractive and promising molecule for the therapeutic management of ulcerative colitis.

The effects of different dietary fiber pectin structures on the gastrointestinal immune barrier: impact via gut microbiota and direct effects on immune cells

“…In addition to the DM-dependent effects, the in vitro effect of RG-I pectins was investigated. RG-I pectins reduced intestinal permeability in Caco-2 cells by maintaining claudin-1 structures 66 . These studies demonstrate that pectins can protect epithelial integrity against barrier-disrupting agents by maintaining tight junction structures.…”

“…High DM pectins are not thought to reach goblet cells to induce mucus secretion, but they may protect the epithelium from harmful mucus-penetrating agents by strengthening the mucus layer. In addition, the pectin structure of RG-I showed protective effects on the mucus layer in mice with DSS-induced colitis 66 . RG-I protected the mucus layer by preserving the number of goblet cells and the expression of Muc-1 66 .…”

“…In addition, the pectin structure of RG-I showed protective effects on the mucus layer in mice with DSS-induced colitis 66 . RG-I protected the mucus layer by preserving the number of goblet cells and the expression of Muc-1 66 . Together, these findings suggest that low DM pectins, high DM pectins or RG-I pectin structures can strengthen gut barrier function by stimulating mucin secretion by goblet cells or through mucus adhesive properties.…”

“…Several studies have shown that pectins have beneficial effects on the integrity of the gastrointestinal mucus layer. Under both healthy and diseased conditions, it has been shown that pectins can strengthen the intestinal mucus layer by influencing goblet cells or by the mucoadhesive effects of pectins 41,[64][65][66] .…”

“…These studies demonstrate that pectins can protect epithelial integrity against barrier-disrupting agents by maintaining tight junction structures. Low DM pectins and very high DM pectins or pectins with RG-I structures may be responsible for these effects 26,29,66 .…”