Intervention with fructooligosaccharides, Saccharomyces boulardii, and their combination in a colitis mouse model.

Objective: To examine the effects of an intervention with fructooligosaccharides (FOS), Saccharomyces boulardii, and their combination in a mouse model of colitis and to explore the mechanisms underlying these effects. Methods: The effects of FOS, S. boulardii, and their combination were evaluated in a DSS-induced mouse model of colitis. To this end, parameters such as body weight, the disease activity index (DAI), and colon length were examined in model mice. Subsequently, ELISA was employed to detect the serum levels of proinflammatory cytokines. Histopathological analysis was performed to estimate the progression of inflammation in the colon. Gas chromatography was used to determine the content of short-chain fatty acids (SCFAs) in the feces of model mice. Finally, 16S rRNA sequencing technology was used to analyze the gut microbiota composition. Results: FOS was slight effective in treating colitis and colitis-induced intestinal dysbiosis in mice. Meanwhile, S. boulardii could significantly reduced the DAI, inhibited the production of IL-1ß, and prevented colon shortening. Nevertheless, S. boulardii treatment alone failed to effectively regulate the gut microbiota. In contrast, the combined administration of FOS/S. boulardii resulted in better anti-inflammatory effects and enabled microbiota regulation. The FOS/S. boulardii combination (109 CFU/ml and 107 CFU/ml) significantly reduced the DAI, inhibited colitis, lowered IL-1ß and TNF-α production, and significantly improved the levels of butyric acid and isobutyric acid. However, FOS/S. boulardii 109 CFU/ml exerted stronger anti-inflammatory effects, inhibited IL-6 production and attenuated colon shortening. Meanwhile, FOS/S. boulardii 107 CFU/ml improved microbial regulation and alleviated the colitis-induced decrease in microbial diversity. The combination of FOS and S. boulardii significantly increased the abundance of Parabacteroides and decreased the abundance of Escherichia-Shigella. Additionally, it promoted the production of acetic acid and propionic acid. Conclusion: Compared with single administration, the combination can significantly increase the abundance of beneficial bacteria such as lactobacilli and Bifidobacteria and effectively regulate the gut microbiota composition. These results provide a scientific rationale for the prevention and treatment of colitis using a FOS/S. boulardii combination. They also offer a theoretical basis for the development of nutraceutical preparations containing FOS and S. boulardii.

Lactobacillus johnsonii alleviates colitis by TLR1/2-STAT3 mediated CD206+ macrophagesIL-10 activation.

Imbalance of gut microbiota homeostasis is related to the occurrence of ulcerative colitis (UC), and probiotics are thought to modulate immune microenvironment and repair barrier function. Here, in order to reveal the interaction between UC and gut microbiota, we screened a new probiotic strain by 16S rRNA sequencing from Dextran Sulfate Sodium (DSS)-induced colitis mice, and explored the mechanism and clinical relevance. Lactobacillus johnsonii (L. johnsonii), as a potential anti-inflammatory bacterium was decreased colonization in colitis mice. Gavage L. johnsonii could alleviate colitis by specifically increasing the proportion of intestinal macrophages and the secretion of Il-10 with macrophages depleted model and in Il10-/- mice. We identified this subset of immune cells activated by L. johnsonii as CD206+ macrophagesIL-10. Mechanistically, L. johnsonii supplementation enhanced the mobilization of CD206+ macrophagesIL-10 through the activation of STAT3 in vivo and in vitro. In addition, we revealed that TLR1/2 was essential for the activation of STAT3 and the recognition of L. johnsonii by macrophages. Clinically, there was positive correlation between the abundance of L. johnsonii and the expression level of MRC1, IL10 and TLR1/2 in UC tissues. L. johnsonii could activate native macrophages into CD206+ macrophages and release IL-10 through TLR1/2-STAT3 pathway to relieve experimental colitis. L. johnsonii may serve as an immunomodulator and anti-inflammatory therapeutic target for UC.

Fermentation properties of isomaltooligosaccharides are affected by human fecal enterotypes.

Isomaltooligosaccharides (IMOs) are enzymatically synthesized oligosaccharides that have potential prebiotic effects. Five IMO substrates with 2-16° of polymerization (DP) were studied for their fermentation capacities using human microbiomes in an in vitro batch fermentation model. Eleven fecal slurries belonging to three enterotypes, including the Bacteroides-, Prevotella- and Mixed-type, exhibited different degradation rates for long chain IMOs (DP 7 to 16). In contrast, the degradation rates for short chain IMOs (DP 2 to 6) were not affected by enterotypes. Both 16S rRNA gene sequencing and quantitative PCR demonstrated that, after fermentation, the Bifidobacterium growth with IMOs was primarily detected in the Bacteroides- and Mixed-type (non-Prevotella-type), and to a lesser degree in the Prevotella-type. Interestingly, the Prevotella-type microbiome had higher levels of propionic acid and butyric acid production than non-Prevotella-type microbiome after IMOs fermentation. Moreover, principal coordinate analysis (PCoA) of both denaturing gradient gel electrophoresis (DGGE) profiling and 16S rRNA sequencing data demonstrated that the microbiome community compositions were separately clustered based on IMO chain length, suggesting significant impact of DP on the bacterial community structure. The current results clearly demonstrated that the IMO chain length could modulate the structure and composition of the human colonic microbiome. Different responses to short and long chain IMOs were observed from three human enterotypes, indicating that IMOs may be used as therapeutic substrates for directly altering human colonic bacteria.

In vitro fermentation of alginate and its derivatives by human gut microbiota.

Alginate (Alg) has a long history as a food ingredient in East Asia. However, the human gut microbes responsible for the degradation of alginate and its derivatives have not been fully understood yet. Here, we report that alginate and the low molecular polymer derivatives of mannuronic acid oligosaccharides (MO) and guluronic acid oligosaccharides (GO) can be completely degraded and utilized at various rates by fecal microbiota obtained from six Chinese individuals. However, the derivative of propylene glycol alginate sodium sulfate (PSS) was not hydrolyzed. The bacteria having a pronounced ability to degrade Alg, MO and GO were isolated from human fecal samples and were identified as Bacteroides ovatus, Bacteroides xylanisolvens, and Bacteroides thetaiotaomicron. Alg, MO and GO can increase the production level of short chain fatty acids (SCFA), but GO generates the highest level of SCFA. Our data suggest that alginate and its derivatives could be degraded by specific bacteria in the human gut, providing the basis for the impacts of alginate and its derivates as special food additives on human health.

[Progress in studying antimicrobial peptides and intestinal health].

Antimicrobial peptides (AMPs) are bioactive short peptides produced in organisms. AMPs have important roles in resisting pathogen invasion. In recent years, several studies on intestinal microecology is hot and the influence of antimicrobial peptides on intestinal health is widely concerned. Relevant results have demonstrated that the expression level of AMPs can be used to assess the body's intestinal health, thereby an auxiliary method could be established through monitoring on the expression level of AMPs during disease prevention and treatment. In this paper, research advances in antimicrobial peptides in intestinal microflora structure and immune effect were summarized and analyzed to provide references for clinical diagnosis and treatment.