Mucin secretion is modulated by luminal factors in the isolated vascularly perfused rat colon

Abstract

Background-Mucins play an important protective role in the colonic mucosa. Luminal factors modulating colonic mucus release have been not fully identified. Aim-To determine the eVect of some dietary compounds on mucus discharge in rat colon. Methods-An isolated vascularly perfused rat colon model was used. Mucus secretion was induced by a variety of luminal factors administered as a bolus of 1 ml for 30 minutes in the colonic loop. Mucin release was evaluated using a sandwich enzyme linked immunosorbent assay supported by histological analysis. Results-The three dietary fibres tested in this study (pectin, gum arabic, and cellulose) did not provoke mucus secretion. Luminal administration of sodium alginate (an algal polysaccharide used as a food additive) or ulvan (a sulphated algal polymer) induced a dose dependent increase in mucin discharge over the concentration range 1-25 mg/l (p<0.05 for 25 mg/l alginate and p<0.05 for 10 and 25 mg/l ulvan). Glucuronic acid and galacturonic acid, which are major constituents of a variety of fibres, produced significant mucin secretion (p<0.05). Hydrogen sulphide and mercaptoacetate, two sulphides produced in the colonic lumen by microbial fermentation of sulphated polysaccharides, did not modify mucin secretion. Among the short chain fatty acids, acetate (5-100 mM) induced a dose dependent release of mucus (p<0.05 for 100 mM acetate). Interestingly, butyrate at a concentration of 5 mM produced colonic mucin secretion (p<0.05), but increasing its concentration to 100 mM provoked a gradual decrease in mucus discharge. Propionate (5-100 mM) did not induce mucin release. Several dietary phenolic compounds (quercetin, epicatechin, resveratrol) did not provoke mucus discharge. Conclusions-Two algal polysaccharides (alginate and ulvan), two uronic acids (glucuronic acid and galacturonic acid), and the short chain fatty acids acetate and butyrate induce mucin secretion in rat colon. Taken together, these data suggest that some food constituents and their fermentation products may regulate the secretory function of colonic goblet cells.

Butyrate specifically modulatesMUCgene expression in intestinal epithelial goblet cells deprived of glucose

“…Our results extend previous reports on the specific role of butyrate on the modulation of mucin synthesis and release (5,16,39). Interestingly, this specific effect of butyrate on mucins has also been described for other cellular functions such as differentiation and programmed cell death (7).…”

“…It has been reported that SCFA stimulate mucin discharge in rats (36). Among three main SCFA produced in the human colon (i.e., acetate, propionate, and butyrate) butyrate appears to be the most effective in modulating mucin synthesis and release (5,16,39). Interestingly, a recent study (2) points to MUC gene expression as a target of SCFA in goblet cells.…”

Streptozotocin-induced type-1-diabetes disease onset in Sprague–Dawley rats is associated with an altered intestinal microbiota composition and decreased diversity

“…Lactic acid producers such as Lactobacillus, Lactococcus, Bifidobacterium and Streptococcus were higher in the faeces of children pre-diagnosed with autoimmune diabetes (Brown et al, 2011). The fate of lactate is crucial in determining intestinal health as conversion to butyrate results in mucin synthesis (Barcelo et al, 2000;Burger-van Paassen et al, 2009;Finnie et al, 1995;Shimotoyodome et al, 2000) and tighter junctions (Peng et al, 2007(Peng et al, , 2009, while conversion to other SCFA, such as propionate and acetate does not induce mucin synthesis (Brown et al, 2011). Mucin is a glycoprotein made by the host that maintains the integrity of intestinal epithelium (Brown et al, 2011).…”

From the gut to the peripheral tissues: the multiple effects of butyrate

“…Butyrate can affect several components of the colonic barrier, leading to an improvement in epithelial colonic defence mechanism: mucin (MUC) production, improvement of intestinal epithelial permeability and modulation of pro-inflammatory cytokines via impairment in NFkB activation. In vitro, butyrate increases expression of the MUC gene (173) but the effect seems to be dose dependent (164) . In Caco-2 cells, a decrease in butyrate increases intestinal permeability (174) and butyrate up-regulates lipoxygenase 5-LOX, 12-LOX and 15-LOX mRNA expression (175) .…”

“…Butyrate administration into the lumen of isolated vascularly perfused rat colon (5 mM) enhanced mucin secretion, but increasing the concentration up to 100 mM provoked a gradual decrease in mucus discharge (164) . In piglets fed a butyrate-supplemented diet, the number of colonic goblet cells was significantly increased (94) .…”