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Bifidobacterium dentium regulates intestinal mucus production and glycosylation
Author(s) -
Engevik Melinda Anne,
Luk Berkley Kristina,
Visuthranukul Chonnikant,
Versalovic James
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.954.5
Subject(s) - mucus , mucin , bifidobacterium bifidum , goblet cell , microbiology and biotechnology , biology , bifidobacterium , intestinal mucosa , chemistry , bacteria , lactobacillus , epithelium , biochemistry , medicine , ecology , genetics
Background Bifidobacteria are commensal organisms in the gastrointestinal tract that are known to exhibit health‐promoting effects. In humans, bifidobacteria are detectable within the first week after birth and are a predominant genus of the infant intestinal microbiota. Previous studies have demonstrated that Bifidobacterium species are able to adhere to and colonize intestinal mucus. The intestinal mucus layer provides both a barrier and interface between the gut microbiota and the host. Mucus is secreted from goblet cells as heavily O‐glycosylated proteins. Disruption of the protective mucus layer has been implicated in several inflammatory diseases. Currently little is known regarding how specific microbes are able to modulate mucus production and glycosylation. We hypothesized that the human commensal Bifiboacterium dentium , a representative member of Bifidobacteria, would modulate O‐glycan synthesis and increase intestinal mucus production. Methods & Results Swiss Webster germ free mice (GF) were mono‐associated with B. dentium , while control GF mice received sterile media gavages. Standard bacterial plating, fecal gDNA and 16S fluorescent in situ hybridization (FISH) were used to confirm colonization of B. dentium . Colon tissue was collected in Trizol for RNA or fixed in Carnoy's fixative to maintain mucus architecture. Mucin mRNA was examined by qPCR and mucin proteins were examined by Periodic Acid Schiff‐Alcian Blue (PAS‐AB) and immunofluorescence. Colonoids were generated from germ free mouse colonic stem cells and grown in matrigel to generate 3‐D structure. B. dentium mono‐associated mice had a 20 fold increase in the goblet cell differentiation marker Kruppel‐Like Factor 4 ( klf4 ) at the level of mRNA compared with GF controls. Likewise, B. dentium mice exhibited increased acidic mucin filled goblet cells as denoted by PAS‐AB stain compared with GF controls. B. dentium mice had a >5‐fold increase in the main secreted mucin Muc2 mRNA and protein, and increased the co‐secreted proteins Trefoil Factor 3 (TFF3) and resistin‐like molecule (Relmβ). Analysis of mucin O‐glycosylation genes revealed that B. dentium upregulated b3gnt6, c1galt1, c2gnt, fut2 and st7gal1 . No changes were observed in Core2‐GlcNAc‐Transferase c2GnT3 . Germ free mouse colonoids express enterocytes, goblet cells, and enteroendocrine cells, similar to native tissue. Microinjection of B. dentium secreted factors into colonoids derived from germ free mice resulted in increased Muc2 production, corresponding to our in vivo findings. Conclusions This work illustrates that the human commensal B. dentium is able to modulate the mucus profile in the colon. As B. dentium is a key colonizer of the infant gut, we speculate that this may be particularly important in the development of a mature mucus barrier and may have effects later in life.