Normalization of Host Intestinal Mucus Layers Requires Long-Term Microbial Colonization

• Published in: Cell host & microbe Vol. 18; no. 5; pp. 582 - 592
• Main Authors: Johansson, Malin E.V., Jakobsson, Hedvig E., Holmén-Larsson, Jessica, Schütte, André, Ermund, Anna, Rodríguez-Piñeiro, Ana M., Arike, Liisa, Wising, Catharina, Svensson, Frida, Bäckhed, Fredrik, Hansson, Gunnar C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 11.11.2015
• Subjects: Animals; bacteria; Bacterial Infections - microbiology; Bacteroides - growth & development; ecosystem; Firmicutes - growth & development; functional cftr channel; Gastrointestinal Microbiome; Germ-Free Life; glycosylation; gut microbiota; homeostasis; immune; Intestinal Mucosa - microbiology; Mice; Microbiology; Mikrobiologi; mouse stomach; mucin; Mucin-2 - metabolism; secretion
• ISSN: 1931-3128; 1934-6069; 1934-6069
• DOI: 10.1016/j.chom.2015.10.007

The intestinal mucus layer provides a barrier limiting bacterial contact with the underlying epithelium. Mucus structure is shaped by intestinal location and the microbiota. To understand how commensals modulate gut mucus, we examined mucus properties under germ-free (GF) conditions and during microbial colonization. Although the colon mucus organization of GF mice was similar to that of conventionally raised (Convr) mice, the GF inner mucus layer was penetrable to bacteria-sized beads. During colonization, in which GF mice were gavaged with Convr microbiota, the small intestine mucus required 5 weeks to be normally detached and colonic inner mucus 6 weeks to become impenetrable. The composition of the small intestinal microbiota during colonization was similar to Convr donors until 3 weeks, when Bacteroides increased, Firmicutes decreased, and segmented filamentous bacteria became undetectable. These findings highlight the dynamics of mucus layer development and indicate that studies of mature microbe-mucus interactions should be conducted weeks after colonization. [Display omitted] •Impenetrable colon mucus forms 6 weeks after conventionalizing germ-free mice•Bacterial composition of the small intestine shifts 3–5 weeks postcolonization•The small intestine mucus layer does not detach until 5 weeks after colonization•Mucus normalizes after 7 weeks and is not reversed by antibiotics The intestinal mucus layer provides a protective barrier and is shaped by microbiota. By examining how microbial colonization modulates gut mucus, Johansson et al. find that it takes 7 weeks for the colonic mucus to normalize and become impenetrable and that the colonizing microbiota undergoes dynamic changes 3 weeks postcolonization.