HumanClostridium difficileinfection: altered mucus production and composition

Abstract

The majority of antibiotic-induced diarrhea is caused by Clostridium difficile (C. difficile). Hospitalizations for C. difficile infection (CDI) have tripled in the last decade, emphasizing the need to better understand how the organism colonizes the intestine and maintain infection. The mucus provides an interface for bacterial-host interactions and changes in intestinal mucus have been linked host health. To assess mucus production and composition in healthy and CDI patients, the main mucins MUC1 and MUC2 and mucus oligosaccharides were examined. Compared with healthy subjects, CDI patients demonstrated decreased MUC2 with no changes in surface MUC1. Although MUC1 did not change at the level of the epithelia, MUC1 was the primary constituent of secreted mucus in CDI patients. CDI mucus also exhibited decreased N-acetylgalactosamine (GalNAc), increased N-acetylglucosamine (GlcNAc), and increased terminal galactose residues. Increased galactose in CDI specimens is of particular interest since terminal galactose sugars are known as C. difficile toxin A receptor in animals. In vitro, C. difficile is capable of metabolizing fucose, mannose, galactose, GlcNAc, and GalNAc for growth under healthy stool conditions (low Na(+) concentration, pH 6.0). Injection of C. difficile into human intestinal organoids (HIOs) demonstrated that C. difficile alone is sufficient to reduce MUC2 production but is not capable of altering host mucus oligosaccharide composition. We also demonstrate that C. difficile binds preferentially to mucus extracted from CDI patients compared with healthy subjects. Our results provide insight into a mechanism of C. difficile colonization and may provide novel target(s) for the development of alternative therapeutic agents.

Polymers in the gut compress the colonic mucus hydrogel

“…For example, a polymer solution [e.g., optimal cutting temperature (OCT) compound] is frequently used in cryosection experiments that seek to preserve mucus structure (e.g., refs. [33][34][35][36]. The polymer-induced compression that we describe in this paper may affect such experiments; indeed, in preliminary experiments, we have found that OCT compound actually alters mucus structure considerably.…”

Human Enteroids/Colonoids and Intestinal Organoids Functionally Recapitulate Normal Intestinal Physiology and Pathophysiology

“…The Spence laboratory demonstrated that luminal exposure of C. difficile in intestinal organoids results in increased paracellular permeability with the C. difficile toxin TcdA having a more potent effect than TcdB (39). In addition, the Worrell laboratory found that luminal C. difficile infection reduces NHE3 and MUC2 protein levels, which may partially explain how C. difficile creates a luminal environment to enhance colonization (40,41). Further studies of infections of human enteroids are expected to lead to identification of novel mechanisms of human response to infection with a wide spectrum of human commensals as well as bacterial, viral, and parasitic pathogens, many of which currently lack animal models.…”

Gleaning Insights from Fecal Microbiota Transplantation and Probiotic Studies for the Rational Design of Combination Microbial Therapies

“…Intestinal biopsy specimens from CDI patients show decreased MUC2 expression levels relative to those in healthy patients (162). C. difficile and CDI stool samples decrease MUC2 levels and alter mucus oligosaccharide composition in cultured human intestinal epithelial cells (162).…”