# Complementary immunoregulatory effects of Bifidobacterium longum 1714TM associated exopolysaccharide and tryptophan metabolism

## TL;DR

This study shows that Bifidobacterium longum 1714 reduces inflammation through its exopolysaccharide and tryptophan metabolism, which may help modulate immune responses and protect the nervous system.

## Contribution

The study identifies complementary mechanisms—exopolysaccharide and tryptophan metabolites—that contribute to the immunomodulatory effects of B. longum 1714.

## Key findings

- B. longum 1714 reduced proinflammatory cytokine responses in human and murine models.
- EPS and tryptophan metabolite ILA increased IL-10 secretion and reduced TLR-induced inflammation.
- Human consumption of B. longum 1714 increased plasma tryptophan and kynurenic acid levels.

## Abstract

•
Bifidobacterium longum 1714 impacts the immune system via multiple mechanisms, reducing peripheral inflammation.
•
B. longum 1714 reduced proinflammatory cytokine responses in stimulated PBMCS and in LPS-, stress-, and obesity-induced murine models.
•
B. longum 1714 consumption in humans increased plasma tryptophan and kynurenic acid levels, supporting immunoregulatory effects.
•
EPS and tryptophan metabolite ILA selectively promoted PBMC IL-10 secretion, while reducing TLR-induced cytokines and NF-κB activation.
•
Intrinsic properties like its cell wall, EPS, and tryptophan metabolism contribute to immunomodulatory and anti-inflammatory effects.

Bifidobacterium longum 1714 impacts the immune system via multiple mechanisms, reducing peripheral inflammation.

B. longum 1714 reduced proinflammatory cytokine responses in stimulated PBMCS and in LPS-, stress-, and obesity-induced murine models.

B. longum 1714 consumption in humans increased plasma tryptophan and kynurenic acid levels, supporting immunoregulatory effects.

EPS and tryptophan metabolite ILA selectively promoted PBMC IL-10 secretion, while reducing TLR-induced cytokines and NF-κB activation.

Intrinsic properties like its cell wall, EPS, and tryptophan metabolism contribute to immunomodulatory and anti-inflammatory effects.

Specific bifidobacterial strains can reduce aberrant inflammatory responses, but the strain-specific factors that promote regulatory immune responses are not well elucidated. The aims of this study were to assess the effects of Bifidobacterium longum 1714™ on innate inflammatory responses and to identify the strain-associated features that mediate its immunomodulatory effects. B. longum 1714 induced peripheral blood mononuclear cell (PBMC) and monocyte derived dendritic cell (MDDC) cytokine secretion and costimulatory molecule expression in a strain specific manner. B. longum 1714 consumption reduced excessive cytokine responses in LPS-induced, stress-induced and obesity-induced inflammation in murine models. B. longum 1714 produced a branched hexasaccharide repeating unit exopolysaccharide (EPS), which selectively induced PBMC secretion of IL-10. Furthermore, B. longum 1714 produced tryptophan and indole lactic acid (ILA) in vitro, and ILA directly reduced TLR-induced proinflammatory cytokine secretion and NF-κB activation. Finally, increased plasma levels of tryptophan and kynurenic acid were identified in humans following B. longum 1714 consumption.

B. longum 1714 influences the immune system through intrinsic features associated with strain specific surface EPS and via secreted metabolic products, which demonstrates the potential for multiple mechanisms through which a specific probiotic may modulate immune responses and potential neuroprotective pathways.

Complementary immunoregulatory effects of Bifidobacterium longum 1714TM associated exopolysaccharide and tryptophan metabolism.Image, graphical abstract

Complementary immunoregulatory effects of Bifidobacterium longum 1714TM associated exopolysaccharide and tryptophan metabolism.