Polysaccharide BAP1 of Bifidobacterium adolescentis CCDM 368 is a biologically active molecule with immunomodulatory properties

Phosphorylation-dependent immunomodulatory properties of B.PAT polysaccharide isolated from Bifidobacterium animalis ssp. animalis CCDM 218

A wide range of articles describe the role of different probiotics in the prevention or treatment of various diseases. However, currently, the focus is shifting from whole microorganisms to their easier-to-define components that can confer similar or stronger benefits on the host. Here, we aimed to describe polysaccharide B.PAT, which is a surface antigen isolated from Bifidobacterium animalis ssp. animalis CCDM 218 and to understand the relationship between its structure and function. For this reason, we determined its glycerol phosphate-substituted structure, which consists of glucose, galactose, and rhamnose residues creating the following repeating unit: To fully understand the role of glycerol phosphate substitution on the B.PAT function, we prepared the dephosphorylated counterpart (B.MAT) and tested their immunomodulatory properties. The results showed that the loss of glycerol phosphate increased the production of IL-6, IL-10, IL-12, and TNF-α in bone marrow dendritic cells alone and after treatment with Lacticaseibacillus rhamnosus GG. Further studies indicated that dephosphorylation can enhance B.PAT properties to suppress IL-1β-induced inflammatory response in Caco-2 and HT-29 cells. Thus, we suggest that further investigation of B.PAT and B.MAT may reveal distinct functionalities that can be exploited in the treatment of various diseases and may constitute an alternative to probiotics.

The Immunomodulatory Effects of Lipoteichoic Acid from Lactobacillus reuteri L1 on RAW264.7 Cells and Mice Vary with Dose

The probiotic properties of Lactobacillus reuteri (L. reuteri) and its impact on immune function are well-documented. Lipoteichoic acid (LTA) is a crucial immune molecule in Gram-positive bacteria. Despite extensive research on LTA's structural diversity, the immunomodulatory mechanisms of L. reuteri LTA remain largely unexplored. This study investigates the immunomodulatory effects of L. reuteri L1 LTA at various concentrations on RAW 264.7 cells and mice under normal and inflammatory conditions. We found that LTA does not significantly affect healthy subjects; however, low-concentration LTA can reduce inflammation induced by LPS in cells and mice, enhancing the abundance of dominant intestinal bacteria. In contrast, high-concentration LTA exacerbates intestinal damage and dysbiosis. Creatinine may play a role in this differential response. In summary, while LTA does not alter immune homeostasis in healthy organisms, low-concentration LTA may mitigate damage from immune imbalance, but high-concentration LTA can worsen it. This suggests a quantitative requirement for probiotic intake. Our study provides critical theoretical support for understanding the immunomodulatory effects of probiotics on the host and paves the way for future research into the immune mechanisms of probiotics.

Pomegranate flower polysaccharide improves mastitis in mice by regulating intestinal flora and restoring the blood-milk barrier

This study explored the inhibitory effect of pomegranate flower polysaccharide (PFPS) on mastitis through in vitro and in vivo models. PFPS is a new type of polysaccharide isolated and extracted from pomegranate flowers. The result revealed that PFPS consists of GalA, Ara, and Gal, and the residues consist of 1,4-GalpA, 1,4-Galp, and 1,3,6-Galp, which contain HG-type and RG-I-type pectin structural domains. In vitro studies showed that PFPS could inhibit LPS-enhanced phagocytosis of RAW 264.7 cells and the release of IL-1β, IL-10, and TNF-α. In vivo, studies showed that PFPS improved xylene-induced mouse ear swelling and carrageenan-induced mouse paw edema by inhibiting inflammatory factors. In the mouse mastitis model, PFPS significantly improved LPS-induced inflammation and oxidative stress in mammary tissue. Intestinal flora sequencing results showed that PFPS could effectively regulate the intestinal flora of mice, reduce the relative abundance of pathogenic bacteria Oscillospira and AF12, and increase the probiotics Blautia, Parabacteroides, Allobaculum, and Clostridiaceae_Clostridium. Therefore, PFPS ultimately played a role in preventing mastitis by regulating the intestinal flora and further improving the blood-milk barrier. This study provides a scientific basis for PFPS as a potential candidate drug for the treatment of mastitis.

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

Bifidobacteria are a prominent type of bacteria that have garnered significant research attention for their exceptional probiotic properties and capacity to produce exopolysaccharides (EPSs). These compounds exhibit diverse physical, chemical, and biological characteristics, prompting numerous investigations into their potential applications. Researchers have noted their beneficial effects as immune modulators within the host's body across various industries. Extensive research has been conducted on the immunomodulatory effects of bifidobacteria-derived EPSs, with emerging engineering strategies aimed at enhancing their immune-modulating capabilities. Understanding the structure, physicochemical properties, and biological activities of these compounds is crucial for their effective utilization across different industries. Our review encompassed numerous studies exploring Bifidobacterium and its metabolites, including EPSs, across various sectors, drawing from diverse databases. The distinctive properties of EPSs have spurred investigations into their applications, revealing their potential to bolster the immune system, combat inflammation, and treat various ailments. Additionally, these compounds possess antioxidant and antimicrobial properties, making them suitable for incorporation into a range of products spanning food, health, and medicine.

metaProbiotics: a tool for mining probiotic from metagenomic binning data based on a language model

Beneficial bacteria remain largely unexplored. Lacking systematic methods, understanding probiotic community traits becomes challenging, leading to various conclusions about their probiotic effects among different publications. We developed language model-based metaProbiotics to rapidly detect probiotic bins from metagenomes, demonstrating superior performance in simulated benchmark datasets. Testing on gut metagenomes from probiotic-treated individuals, it revealed the probioticity of intervention strains-derived bins and other probiotic-associated bins beyond the training data, such as a plasmid-like bin. Analyses of these bins revealed various probiotic mechanisms and bai operon as probiotic Ruminococcaceae's potential marker. In different health-disease cohorts, these bins were more common in healthy individuals, signifying their probiotic role, but relevant health predictions based on the abundance profiles of these bins faced cross-disease challenges. To better understand the heterogeneous nature of probiotics, we used metaProbiotics to construct a comprehensive probiotic genome set from global gut metagenomic data. Module analysis of this set shows that diseased individuals often lack certain probiotic gene modules, with significant variation of the missing modules across different diseases. Additionally, different gene modules on the same probiotic have heterogeneous effects on various diseases. We thus believe that gene function integrity of the probiotic community is more crucial in maintaining gut homeostasis than merely increasing specific gene abundance, and adding probiotics indiscriminately might not boost health. We expect that the innovative language model-based metaProbiotics tool will promote novel probiotic discovery using large-scale metagenomic data and facilitate systematic research on bacterial probiotic effects. The metaProbiotics program can be freely downloaded at https://github.com/zhenchengfang/metaProbiotics.

Exploring probiotic effector molecules and their mode of action in gut-immune interactions

Probiotics, live microorganisms that confer health benefits when consumed in adequate amounts, have gained significant attention for their potential therapeutic applications. The beneficial effects of probiotics are believed to stem from their ability to enhance intestinal barrier function, inhibit pathogens, increase beneficial gut microbes, and modulate immune responses. However, clinical studies investigating the effectiveness of probiotics have yielded conflicting results, potentially due to the wide variety of probiotic species and strains used, the challenges in controlling the desired number of live microorganisms, and the complex interactions between bioactive substances within probiotics. Bacterial cell wall components, known as effector molecules, play a crucial role in mediating the interaction between probiotics and host receptors, leading to the activation of signaling pathways that contribute to the health-promoting effects. Previous reviews have extensively covered different probiotic effector molecules, highlighting their impact on immune homeostasis. Understanding how each probiotic component modulates immune activity at the molecular level may enable the prediction of immunological outcomes in future clinical studies. In this review, we present a comprehensive overview of the structural and immunological features of probiotic effector molecules, focusing primarily on Lactobacillus and Bifidobacterium. We also discuss current gaps and limitations in the field and propose directions for future research to enhance our understanding of probiotic-mediated immunomodulation.