Stress disrupts intestinal mucus barrier in rats via mucin O-glycosylation shift: prevention by a probiotic treatment

Abstract

Despite well-known intestinal epithelial barrier impairment and visceral hypersensitivity in irritable bowel syndrome (IBS) patients and IBS-like models, structural and physical changes in the mucus layer remain poorly understood. Using a water avoidance stress (WAS) model, we aimed at evaluating whether 1) WAS modified gut permeability, visceral sensitivity, mucin expression, biochemical structure of O-glycans, and related mucus physical properties, and 2) whether Lactobacillus farciminis treatment prevented these alterations. Wistar rats received orally L. farciminis or vehicle for 14 days; at day 10, they were submitted to either sham or 4-day WAS. Intestinal paracellular permeability and visceral sensitivity were measured in vivo. The number of goblet cells and Muc2 expression were evaluated by histology and immunohistochemistry, respectively. Mucosal adhesion of L. farciminis was determined ex situ. The mucin O-glycosylation profile was obtained by mass spectrometry. Surface imaging of intestinal mucus was performed at nanoscale by atomic force microscopy. WAS induced gut hyperpermeability and visceral hypersensitivity but did not modify either the number of intestinal goblet cells or Muc2 expression. In contrast, O-glycosylation of mucins was strongly affected, with the appearance of elongated polylactosaminic chain containing O-glycan structures, associated with flattening and loss of the mucus layer cohesive properties. L. farciminis bound to intestinal Muc2 and prevented WAS-induced functional alterations and changes in mucin O-glycosylation and mucus physical properties. WAS-induced functional changes were associated with mucus alterations resulting from a shift in O-glycosylation rather than from changes in mucin expression. L. farciminis treatment prevented these alterations, conferring epithelial and mucus barrier strengthening.

The role of the commensal microbiota in adaptive and maladaptive stressor-induced immunomodulation

“…For example, chronic subordinate colony housing, water avoidance stress, and water immersion, in rats significantly reduces the number of mucous-producing cells, thickness of the mucous barrier, and the production of the mucin Muc2 in the colon (Da Silva et al, 2014; Nyuyki et al, 2012; Shigeshiro, 2012). Thus, although it has been recognized for approximately 100 years that stress can change gastrointestinal system functioning, the extent of the effects of stressor exposure on GI functioning, as well as some of the mechanisms by which they occur, are increasingly well defined.…”

The Effect of Low Protein on Colonic Mucosal Barrier in Pigs

“…The number of the positively stained goblet cells was determined for 10 full-length crypts using Image-ProPlus software, version 6.0 (Media Cybernetics). The values were averaged per crypt for each tissue sample (Da Silva et al, 2014).…”

Exercise and gut immune function: evidence of alterations in colon immune cell homeostasis and microbiome characteristics with exercise training

“…To this point, our laboratory recently found that forced and voluntary exercise differentially alters the microbiome in both the cecum and feces of mice. 61 Despite these findings, the regulation of mucin and bacterial dynamics are largely understudied in response to exercise, especially in humans. For example, we found that FTR significantly upregulated Ruminococcus gnavus, 35 a mucus-degrading bacteria that contains an intramolecular trans-sialidase enzyme and a Nan cluster, which together allow the bacteria to both degrade and consume terminal sialic acid residues on the mucin glycoprotein structure.…”