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Gutierrez et al. Microbiome Res Rep 2023;2:36 https://dx.doi.org/10.20517/mrr.2023.37 Page 11 of 23

Table 3. Literature review of the positive effects of Bifidobacteria on mucus expression, mucin levels and mucus expulsion
Bifidobacterium species Finding Experimental model Ref.
B. infantis Increased mucus secretion LS174T cells [126]
B. breve Increased mucus secretion LS174T cells [126]
B. longum Increased mucus secretion LS174T cells [126]
VSL#3 Increased mucus secretion LS174T cells [126]
VSL#3 Increased MUC2 expression and secretion Rat colonic loops [126]
B. dentium ATCC 27678 Increased mucus expression and secretion T84 cells [18]
B. dentium ATCC 27678 Increased MUC2 expression and mucus levels Adult gnotobiotic mice [18]
B. bifidum FPLC AA22 Increased mucus levels Adult gnotobiotic mice [129]
B. longum FPLC 117 Increased mucus levels Adult gnotobiotic mice [128]
B. breve UCC2003 Increased MUC2 expression Neonatal conventional mice [35]
B. breve (probiotic cocktail) Increased goblet cells per crypt and increased mucus levels Adult conventional mice [130]

Figure 2. Representative diagram of Bifidobacterium-goblet cell interactions. (A) Bifidobacterium species can generate acetate, which can
elevate MUC2 expression and protein; (B) Bifidobacterium species can also generate varying levels of GABA, which can activate
autophagy-driven expulsion of mucus. Through these mechanisms, Bifidobacteria are speculated to positively regulate goblet cells.
GABA: B. dentium-generated gamma-aminobutyric acid.

containing B. breve also increased the number of goblet cells per crypt and increased the production of
mucus compared with controls . Collectively, these data indicate that Bifidobacterium strains influence
[130]
goblet cell function and mucus production.

Modulation of mucus by Bifidobacteria in inflammation and infectious diseases
There is a wide array of data that demonstrate the substantial benefits of Bifidobacterium in the context of
disease. Colitis is one of the most frequently investigated intestinal diseases, and a variety of Bifidobacterium
species have exhibited the ability to alleviate major complications of colitis. In general, Bifidobacterium
species have been shown to (1) limit inflammation-associated goblet cell and mucus depletion and MUC2
and (2) reduce pro-inflammatory cytokines [Figure 3, Tables 4 and 5].