Bifidobacterium mechanisms of immune modulation and tolerance

Abstract

Bifidobacterium is a widely distributed commensal bacterial genus that displays beneficial pro-homeostatic and anti-inflammatory immunomodulatory properties. Depletion or absence of Bifidobacterium in humans and model organisms is associated with autoimmune responses and impaired immune homeostasis. At the cellular level, Bifidobacterium upregulates suppressive regulatory T cells, maintains intestinal barrier function, modulates dendritic cell and macrophage activity, and dampens intestinal Th2 and Th17 programs. While there has been a large volume of literature characterizing the probiotic properties of various Bifidobacterial species, the likely multifactorial mechanisms underlying these effects remain elusive, in particular, its immune tolerogenic effect. However, recent work has shed light on Bifidobacterium surface structural polysaccharide and protein elements, as well as its metabolic products, as commensal mediators of immune homeostasis. This review aims to discuss several mechanisms Bifidobacterium utilizes for immune modulation as well as their indirect impact on the regulation of gut microbiome structure and function, from structural molecules to produced metabolites. These mechanisms are pertinent to an increasingly networked understanding of immune tolerance and homeostasis in health and disease.

Gut microbiota and risk of coronary heart disease: a two-sample Mendelian randomization study

“…Secondly, with the deepening of research on Bifidobacterium , the types of Bifidobacterium found are also gradually increasing. In the latest study, the Bifidobacterium obtained based on 16S rDNA sequencing technology was divided into 34 different species, including Bifidobacterium adolescium , Bifidobacterium keratobium , and Bifidobacterium animalis ( 33 ). The roles and benefits of some Bifidobacterium species have been found, including immune regulation, promoting tolerance, and playing a protective role in cardiovascular diseases.…”

Bifidobacterium exopolysaccharides: new insights into engineering strategies, physicochemical functions, and immunomodulatory effects on host health

“…Murine B. pseudolongum UMB287 MBP-01 EPS increases intestinal Tregs, whereas porcine-derived B. pseudolongum ATCC25526 EPS does not. However, EPS from both strains lead to increased dendritic cells (DCs), mesenteric lymph node (MLN) DCs, and intestinal MLN macrophages ( Hickey et al, 2021 ; Gavzy et al, 2023 ).…”

“…In vitro studies involving the treatment of DCs with Bifidobacterium bifidum PRI1, followed by co-culture with naïve CD4 T cells, have demonstrated enhanced induction of regulatory T cells (Tregs) and production of interleukin-10 (IL-10; Gavzy et al, 2023 ). These findings underscore the immunomodulatory capabilities of Bifidobacterium EPS, particularly in promoting immune tolerance and anti-inflammatory responses mediated by Tregs and IL-10.…”

“…For instance, in a study involving mice treated with Bifidobacterium adolescentis ATCC15703, lower levels of pro-inflammatory cytokines such as TNFα, IL-6, IL-1β, IL-18, IL-22, and IL-9 were observed compared to the control group. Conversely, higher levels of the anti-inflammatory cytokine IL-10 and the cytokines IL-4 and IL-5, along with increased regulatory T cells (Tregs), were detected in the colons of colitis mice receiving B. adolescentis ATCC15703 ( Gavzy et al, 2023 ). These findings underscore the strain-specific immunomodulatory effects of probiotic bacteria and highlight their potential therapeutic implications in inflammatory conditions.…”

“…Cytokines serve as soluble mediators of host defense responses, playing crucial roles in both specific and non-specific mechanisms for eliminating foreign antigens ( Ashraf and Shah, 2014 ). The cell surface components of B. longum strains NCC 2705, ATCC 15707, and BIF53 have been shown to stimulate the production of IL-10 and TNFα in isolated peripheral blood mononuclear cells ( Gavzy et al, 2023 ).…”