The effect of inulin-type fructans on the intestinal immune function of antibiotic-treated mice

Human Milk Oligosaccharide Lacto-N-Neotetraose Promotes Gut Microbiota Recovery in the Context of Antibiotic-Induced Dysbiosis

Human milk oligosaccharides (HMOs) may shape intestinal homeostasis, although the optimal form of HMOs to restore the gut microbiota in antibiotic-induced dysbiosis remains unclear. Here, we found that HMOs with various structures modulate microbial communities differently after antibiotic exposure. Lacto-N-neotetraose (LNnT) better promotes the recovery of intestinal microbiota (chiefly Lactobacillus) and increases the level of Bifidobacterium compared to 3'-sialyllactose, 2'-fucosyllactose, and the mixture. Additionally, LNnT decreases the potential pathogenic bacteria Klebsiella level and the microbial dysbiosis index. Although supplementation with LNnT does not decrease the Clostridioides difficile burden or alleviate the decline in the fecal numbers of Lactobacillus and Bifidobacterium after C. difficile infection (CDI), LNnT attenuates intestinal epithelial damage, decreases inflammatory status, and alters metabolome profiles after CDI. Collectively, LNnT may function as a promising prebiotic to promote gut microbiota recovery in the context of antibiotic-induced dysbiosis.

Evaluating the Efficacy of Secondary Metabolites in Antibiotic-Induced Dysbiosis: A Narrative Review of Preclinical Studies

BACKGROUND/OBJECTIVES

Drug-induced dysbiosis, particularly from antibiotics, has emerged as a significant contributor to chronic diseases by disrupting gut microbiota composition and function. Plant-derived secondary metabolites, such as polysaccharides, polyphenols, alkaloids, and saponins, show potential in mitigating antibiotic-induced dysbiosis. This review aims to consolidate evidence from preclinical studies on the therapeutic effects of secondary metabolites in restoring gut microbial balance, emphasizing their mechanisms and efficacy.

METHODS

A narrative review was conducted using PubMed, Scopus, and Web of Science. Studies were selected based on specific inclusion criteria, focusing on animal models treated with secondary metabolites for antibiotic-induced dysbiosis. The search terms included "gut microbiota", "antibiotics", and "secondary metabolites". Data extraction focused on microbial alterations, metabolite-specific effects, and mechanisms of action. Relevant findings were systematically analyzed and summarized.

RESULTS

Secondary metabolites demonstrated diverse effects in mitigating the impact of dysbiosis by modulating gut microbial composition, reducing inflammation, and supporting host biological markers. Polysaccharides and polyphenols restored the Firmicutes/Bacteroidetes ratio, increased beneficial taxa such as Lactobacillus and Bifidobacterium, and suppressed pathogenic bacteria like Escherichia-Shigella. Metabolites such as triterpenoid saponins enhanced gut barrier integrity by upregulating tight junction proteins, while alkaloids reduced inflammation by modulating proinflammatory cytokines (e.g., TNF-α, IL-1β). These metabolites also improved short-chain fatty acid production, which is crucial for gut and systemic health. While antibiotic-induced dysbiosis was the primary focus, other drug classes (e.g., PPIs, metformin) require further investigation.

CONCLUSIONS

Plant-derived secondary metabolites show promise in managing antibiotic-induced dysbiosis by restoring microbial balance, reducing inflammation, and improving gut barrier function. Future research should explore their applicability to other types of drug-induced dysbiosis and validate findings in human studies to enhance clinical relevance.

Barley polysaccharides inhibit colorectal cancer by two relatively independent pathways

Colorectal cancer is one of the most common types of cancer worldwide that can lead to serious injury and death. Although polysaccharides are widely recognized as having antitumor activity, there has been little research on the role of barley polysaccharides (BP)1 in colorectal cancer. The results of our research suggest that BP (300 mg/kg) had a significant inhibitory effect on colorectal cancer, and this effect was achieved through two pathways. First, BP can directly promote the secretion of protective metabolites like 5-(4-Hydroxyphenyl)-5-phenylimidazolidine-2,4-dione and 2,3-Bis(4-hydroxyphenyl)propionitrile thereby inhibiting the cancer pathways such as ERK, PI3K, WNT, JAK-STAT, Calcium, and Cell cycle cancer pathways to alleviate inflammation. Second, BP also can enrich beneficial intestinal bacteria such as Colidextribacter, Bilophila, and UCG-003 improve the intestinal barrier, promote the production of beneficial metabolites such as 5,8-Epoxy-5,8-dihydro-3-hydroxy-8'-apo-b,y-carotenal and L-Glutamic acid, and thus inhibit cancer pathways such as ERK, PI3K, Nuclear receptor, Cell cycle, Apoptosis and TGF-β. In conclusion, our findings suggest for the first time that BP can alleviate colorectal cancer by two relatively independent pathways: direct action and indirect action via the gut microbiota on both colon tumor cells and microbiota.

Mannan-oligosaccharides promote gut microecological recovery after antibiotic disturbance

Antibiotic treatment often causes collateral damage to the gut microbiota, including changes in its diversity and composition. Dietary fiber helps maintain intestinal health, regulate short-chain fatty acids, and promote the recovery of the intestinal microbiome. However, it is currently unknown which specific plant-based dietary fiber is optimal as a dietary supplement for restoring the intestinal microbiota after antibiotic disturbance. Previously, we proposed predictive recovery-associated bacterial species (p-RABs) and identified the most important interventions. This study aimed to identify an optimal form of dietary fiber to recover the gut microbiome after antibiotic treatment. Therefore, we examined the types of dietary fibers associated with p-RABs through a p-RAB-metabolite bilayer network constructed from prior knowledge; we searched for dietary fiber that could provide nutritional support for Akkermansia muciniphila and Bacteroides uniformis. C57BL/6J mice were fed with 500 mg kg-1 of different types of dietary fibers daily for one week after being treated with ampicillin. The results showed that mannan-oligosaccharides could better promote the diversity of intestinal microbial growth, enhance the recovery of most genera, including Akkermansia and Bacteroides, and inhibit certain pathogenic bacteria, such as Proteus, compared to the other fiber types. Furthermore, mannan-oligosaccharides could regulate the levels of short-chain fatty acids, especially butyric acid. Functional predictions showed that starch metabolism, galactose metabolism, and the metabolism of other carbohydrates played key roles in the early recovery process. In conclusion, mannan-oligosaccharides could enhance the recovery of the intestinal microbiome after antibiotic treatment, offering valuable insights for targeted dietary strategies.

Immunomodulatory effects of inulin and its intestinal metabolites

"Dietary fiber" (DF) refers to a type of carbohydrate that cannot be digested fully. DF is not an essential nutrient, but it plays an important part in enhancing digestive capacity and maintaining intestinal health. Therefore, DF supplementation in the daily diet is highly recommended. Inulin is a soluble DF, and commonly added to foods. Recently, several studies have found that dietary supplementation of inulin can improve metabolic function and regulate intestinal immunity. Inulin is fermented in the colon by the gut microbiota and a series of metabolites is generated. Among these metabolites, short-chain fatty acids provide energy to intestinal epithelial cells and participate in regulating the differentiation of immune cells. Inulin and its intestinal metabolites contribute to host immunity. This review summarizes the effect of inulin and its metabolites on intestinal immunity, and the underlying mechanisms of inulin in preventing diseases such as type 2 diabetes mellitus, inflammatory bowel disease, chronic kidney disease, and certain cancer types.