Intestinal Metabolites Research Articles

Insights Into Metabolic Signatures and Regulatory Effect of Dendrobium officinale Polysaccharides in Gut Microbiota: A Comparative Study of Healthy and Diabetic Status

ABSTRACTDendrobium officinale is a kind of popular functional food to be consumed by both healthy and diabetic people. As its major constituent, D. officinale polysaccharide (DOP) is mainly utilized by gut microbiota. Despite distinctive gut microbiota composition between healthy and diabetic individuals, no study compared the interplay between DOP and gut microbiota under healthy and diabetic status. The current study aims to investigate and compare the metabolic signatures and regulatory potential of DOP on gut microbiota between healthy and diabetic status. Our serial in vitro fermentation investigations found that mannose in DOP was more utilized by gut microbiota under diabetic status with higher production of propanoic acid and lower production of butyric acid compared with those under healthy status. Moreover, metabolomic analyses revealed different impacts of DOP on intestinal microbial metabolites between healthy and diabetic status with upregulating taurine and downregulating 2‐hydroxybutyric acid only occurring under diabetic status. Biodiversity analyses demonstrated that DOP treatment could only significantly improve the diversity of gut microbiota under diabetic status while there was no significant effect on that under healthy status. Further gut microbiota composition analyses indicated that DOP treatment could promote probiotics (Dubosiella, Bifidobacterium, and Akkermansia) under both healthy and diabetic status while inhibit pathogens (Escherichia‐Shigella) only under diabetic status. In summary, our current insights into metabolic signatures and regulatory effects of DOP in the gut microbiota under healthy and diabetic status provided scientific evidence for its broad use as functional food.

Degradation of low-molecular-weight fucoidans by human intestinal microbiota and their regulation effect on intestinal microbiota and metabolites during in vitro fermentation

Fucoidan, a sulfated polysaccharide from brown algae, has been shown to improve gut microbiota balance and function. However, the relationship between molecular weight of fucoidan and colonic fermentation characteristics is still unclear. Here, the interaction between different-molecular-weight fucoidans and intestinal microbiota was analyzed via an in vitro fecal fermentation model. Results showed that fucoidan and its 2 low-molecular-weight derivatives (Dfuc1 and Dfuc2) could be utilized by intestinal microbiota after 48 h of fermentation, and among them, Dfuc2 exhibited the highest utilization efficiency of 30.1%, followed by Dfuc1 (24.5%) and fucoidan (14.4%). Notably, the components glucose, mannose and galactose, but not fucose, in different-molecular-weight fucoidans could be utilized. Moreover, intestinal microbiota could degrade Dfuc1 and Dfuc2 to produce oligosaccharide fragments, such as fucose-hexose disaccharide. In addition, fucoidan, Dfuc1 and Dfuc2 displayed different prebiotic effects on the intestinal microbiota community. Native fucoidan preferred to promote Bacteroides and Lactococcus, and low-molecular-weight fucoidans tended to promote Parabacteroides and Lactobacillus. Furthermore, metabolites analysis showed that fucoidan, Dfuc1 and Dfuc2 had similar promoting effects on acetic acid and propionic acid, and had no effect on butyric acid. But they could regulate carbohydrate metabolic pathways and amino acid pathways to varying degrees and with decreasing molecular weight, more differential metabolites were found. Thus, Dfuc2 with a lower molecular weight has more potential to become a potential prebiotics to improve intestinal health.

The cross-talk between the metabolome and microbiome in a double-hit neonatal rat model of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), a chronic lung disease in preterm infants, is associated with inflammation and high oxygen exposure. However, the effects of antenatal inflammation and postnatal extended hyperoxia on the metabolome and microbiome remain unclear. In this study, pregnant rats received lipopolysaccharide or saline injections on gestational day 20 and were exposed to either 21 % or 80 % oxygen for 4 weeks post-birth. Analysis revealed an increase in Firmicutes, Proteobacteria, and Actinobacteria, with a decrease in Bacteroidetes in BPD rats. Metabolomic analysis identified 78 altered metabolites, primarily lipids, enriched in pathways including arginine biosynthesis, sphingolipid metabolism, and primary bile acid biosynthesis in BPD rats. Integration analysis revealed strong correlations between intestinal microbiota and metabolites in BPD rats. These findings underscored the impact of antenatal inflammation and prolonged postnatal hyperoxia on gut microbiota and serum metabolome, suggesting their role in BPD pathogenesis.

Regionalization of intestinal microbiota and metabolites in the small intestine of the Bactrian camel

IntroductionPeyer's patches (PPs) are crucial antigen-inductive sites of intestinal mucosal immunity. Prior research indicated that, in contrast to other ruminants, PPs in the small intestine of Bactrian camels are found in the duodenum, jejunum, and ileum and display polymorphism. Using this information, we analyzed the microbial and metabolic characteristics in various segments of the Bactrian camel's small intestine to further elucidate how the immune system varies across different regions. MethodsIn this study, the microbiota and metabolite of 36 intestinal mucosal samples, including duodenal (D-PPs), jejunal (J-PPs), and ileal PPs (I-PPs), were profiled for six Bactrian camels using 16S rRNA gene sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS). To confirm meaningful associations, we conducted connection analyses on the significantly different objects identified in each group's results. ELISA was used to analyze the levels of IgA, IgG, and IgM in the same tissues. ResultsThe microbiota and metabolite profiles of J-PPs and I-PPs were found to be similar, whereas those of D-PPs were more distinct. In J-PPs and I-PPs, the dominant bacterial genera included Clostridium, Turicibacter, and Shigella. In contrast, D-PPs had a significant increase in the abundance of Prevotella, Fibrobacter, and Succinobacter. Regarding the metabolomics, D-PPs exhibited high levels of polypeptides, acetylcholine, and histamine. On the other hand, J-PPs and I-PPs were characterized by an enrichment of free amino acids, such as L-arginine, L-glutamic acid, and L-serine. These metabolic differences mainly involve amino acid production and metabolic processes. Furthermore, the distribution of intestinal immunoglobulins highlighted the specificity of D-PPs. Our results indicated that proinflammatory microbes and metabolites were significantly enriched in D-PPs. In contrast, J-PPs and I-PPs contained substances that more effectively enhance immune responses, as evidenced by the differential distribution of IgA, IgG, and IgM.DiscussionThe intestinal microenvironment of Bactrian camels displays distinct regional disparities, which we propose are associated with variations in immunological function throughout different segments of the small intestine. This study highlights the specific traits of the intestinal microbiota and metabolites in Bactrian camels, offering a valuable reference for understanding the relationship between regional intestinal immunity and the general health and disease of the host.

Effects of Saccharomyces boulardii on microbiota composition and metabolite levels in the small intestine of constipated mice

Saccharomyces boulardii (S. boulardii) is a fungal probiotic used to treat digestive disorders. However, the mechanism(s) by which S. boulardii affects the small intestine remains unclear. Here, we aimed to explore the effects of S. boulardii on the small intestine and the underlying mechanisms in mice with loperamide-induced constipation. While S. boulardii administration did not fully reverse the alterations in loperamide-induced defecation parameters, it altered the small intestinal floral composition toward a community conducive to alleviate constipation. Moreover, S. boulardii up-regulated the expression of tyrosine-protein kinase Kit (c-Kit), aquaporin 3 (AQP3), interleukin (IL)-10, myosin light chain kinase (MLCK), and phosphorylated myosin light chain 20 (P-MLC20), while concurrently down-regulating the expression levels of inducible nitric oxide synthase (iNOS), p65, and IL-17 A. These alterations indicate a discernible effect of small intestinal water reabsorption, inflammatory factor levels, and smooth muscle contraction. Saccharomyces boulardii also positively regulated small intestinal metabolite levels, such as fructose 6-phosphate, dihomo-alpha-linolenic acid, and 3-(4-hydroxyphenyl) lactate, and participated in metabolic pathways such as arginine biosynthesis, linoleic acid metabolism, and protein digestion and absorption. While not fully reversing defecation changes, Saccharomyces boulardii alters intestinal flora, up-regulates key proteins affecting water reabsorption and inflammation, and positively influences metabolic pathways. Our study provides serves as a basis for further studies on the application of S. boulardii in the treatment of intestinal disorders.

Effect of Oat Hay as a Substitute for Alfalfa Hay on the Gut Microbiome and Metabolites of Yak Calves.

To evaluate the impact of different roughages on the intestinal microbiota of yak calves, we fed them oat hay in substitution of alfalfa hay, in addition to milk replacer and starter powder. Twenty-one 45-day-old male yak calves were selected and randomly assigned to three groups: the milk replacer + starter + alfalfa hay group (AH), the milk replacer + starter + oat hay group (OH), and the milk replacer + starter + mixed hay group (AO), in which the alfalfa hay and oat hay were administered in a 1:1 ratio. All calves in the three groups were fed the same milk replacer and an equivalent amount of dry matter. The formal experiment commenced after a 21-day pre-test period and lasted for 120 days. Following the experiment, the contents of the jejunum and colon were collected to investigate the intestinal microbiota and metabolites using 16S rRNA sequencing and LC-MS metabolomics. The result showed that the AO group had greater final body weights overall than the AH group and OH group (p < 0.05). The AH group and OH group had considerably greater feed-to-gain ratios than the AO group (p < 0.05). At the phylum level, the OH group exhibited an increased relative abundance of Bacteroidota and Spirochaetota in the jejunum (p < 0.05). The relative abundance of Actinobacteriota in the colon was increased in the AO group (p < 0.05). At the genus level, the AO group exhibited a decreased abundance of Clostridium sensu_stricto_1 (p < 0.05), and the OH group showed an increased abundance UCG-005 and Alistipes in the jejunum. There were many differential metabolites in the OH group and AO group compared to the AH group, and the different metabolites of the OH group were associated with the metabolic pathways of the nervous system, sensory system, amino acid metabolism, and lipid metabolism in the jejunum and with lipid metabolism, amino acid metabolism, and the nervous system in the colon. In the AO group, these metabolites were associated with the digestive system and the translation and metabolism of cofactors in the jejunum and with the metabolism of cofactors and vitamins in the colon. In summary, it is feasible to replace alfalfa hay with oat hay based on milk replacer and starter. The combination of the two forages enhanced nutrient absorption, improved immune function, maintained the internal homeostasis of yak calves, and was more beneficial to their growth and development.

Macrophytes mitigate Microcystis aeruginosa-induced fish appetite suppression via intestinal metabolite regulation

Cyanobacterial blooms and aquatic macrophytes can affect the health, physiology, and behavior of freshwater fish. Changes in food intake can be a key indicator of stress in teleost fish, while changes in metabolite abundance in the gut can indicate a shift in metabolic priorities, including response to environmental stressors. Here, we exposed stone moroko (Pseudorasbora parva) to the cyanobacterium Microcystis aeruginosa and/or the macrophyte Ottelia acuminata and analyzed changes in fish health, appetite regulation, and intestinal metabolome after 96-h exposures. We found that O. acuminata treatment didn’t change the tested indicators, while exposure to M. aeruginosa increased concentrations of appetite-inhibiting factors, such as CART and GLP-1, and decreased concentrations of stimulatory factors like orexin. Exploration of the metabolome following exposure revealed that the appetite-inhibiting influence of M. aeruginosa was positively correlated with key metabolites of lipid, amino acid, and cholesterol metabolism, especially those associated with bile acid synthesis and secretion. Further, the presence of O. acuminata decreased the adverse effects of M. aeruginosa among neuro-endocrine regulatory factors, which could be explained by altered regulation of intestinal amino acid metabolites. The deeper mechanism by which O. acuminata moderates the harmful effects of M. aeruginosa remains to be identified.

Herbal formula xuling-jiangu improves bone metabolic balance in rats with ovariectomy-induced osteoporosis via the gut-bone axis.

The XuLing JianGu recipe (XLJGR) is an empirical traditional Chinese medicine formula used for the treatment of osteoporosis. This study aims to explore the effects of XLJGR on the intestinal microbiota composition and endogenous metabolites in ovariectomized (OVX) rats. An OVX rat model was established to evaluate the intervention effects of XLJGR. The measured indicators included bone density, serum bone metabolism markers, and an analysis of the types and abundances of intestinal microbiota, along with changes in endogenous metabolites. Additionally, MC3T3-E1 cells were used to validate the differential metabolites. XLJGR significantly reduced the abundance of Bacteroides, Butyricicoccus, and other bacterial strains in the gut. KEGG metabolic pathway enrichment analysis showed that XLJGR intervention led to notable changes in pathways such as peptidoglycan biosynthesis, carbapenem biosynthesis, and vancomycin resistance. Moreover, XLJGR significantly upregulated key intestinal microbiota metabolites, including gabapentin(GAB), camphoric acid(CAA), and nonanedioic acid(AZA), thereby promoting the proliferation and osteogenic differentiation of MC3T3-E1 cells. This study highlights the potential biomedical applications of XLJGR in promoting bone health by positively affecting intestinal microbiota and metabolic characteristics. These findings suggest that XLJGR may serve as a viable alternative in the treatment of osteoporosis, warranting further exploration of its therapeutic mechanisms and clinical applications.

Pre-ADMET studies of 5-(3',4'-dihydroxyphenyl)-γ-valerolactone, the bioactive intestinal metabolite of proanthocyanidins.

5-(3',4'-Dihydroxyphenyl)-γ-valerolactone (VL) is a bioactive metabolite resulting from the gut microbial metabolism of proanthocyanidins and flavonoids, known for its health-promoting effects, including antidiabetic and anti-inflammatory activities. Although VL has been observed in different in vivo studies, its pre-absorption, distribution, metabolism, excretion, toxicity (ADMET)properties have rarely been investigated. This study aims to address this gap by evaluating the pre-ADMET properties of VL for the first time. Also, the understanding of these properties is significant for correlating the encountered activities to this metabolite. In vitro absorption studies revealed that VL is rapidly metabolized and absorbed as its sulfate phase II conjugate (valerolactone sulfate), which enters systemic circulation and mildly activates the Breast Cancer Resistance Protein efflux transporter. In human S9 liver fraction, a mixture of liver enzymes used to simulate in vivo liver metabolism, VL is metabolized into glucuronic phase II conjugates (valerolactone glucuronide 1 [VLG1] and 2 [VLG2]) with a half-life of 8.72 min and an 80% conversion rate. In human liver microsomes, VL is metabolized at a slower rate (half-life of 23.08 min), suggesting that oxidative metabolism is secondary. Additionally, VL did not activate the pregnane X receptor or inhibit Cytochrome P3A4 (CYP3A4) and Cytochrome P1A2(CYP1A2) enzymes, indicating no risk of herb-drug interactions with coadministered prescription drugs.

The gut microbial metabolite indole-3-aldehyde alleviates impaired intestinal development by promoting intestinal stem cell expansion in weaned piglets

BackgroundWeaning stress-induced diarrhea is widely recognized as being associated with gut microbiota dysbiosis. However, it has been challenging to clarify which specific intestinal microbiota and their metabolites play a crucial role in the antidiarrhea process of weaned piglets.ResultsIn this study, we first observed that piglets with diarrhea exhibited a lower average daily gain and higher diarrhea score, and elevated levels of lipopolysaccharide (LPS) and D-lactate (D-LA) compared to healthy piglets. Subsequently, we analyzed the differences in intestinal microbial composition and metabolite levels between healthy and diarrheal weaned piglets. Diarrheal piglets demonstrated intestinal microbiota dysbiosis, characterized primarily by a higher Firmicutes to Bacteroidota ratio, a deficiency of Lactobacillus amylovorus and Lactobacillus reuteri, and an increased abundance of Bacteroides sp.HF-5287 and Bacteroides thetaiotaomicron. Functional profiling of the gut microbiota based on Kyoto Encyclopedia of Genes and Genomes (KEGG) data was performed, and the results showed that tryptophan metabolism was the most significantly inhibited pathway in piglets with diarrhea. Most tryptophan metabolites were detected at lower concentrations in diarrheal piglets than in healthy piglets. Furthermore, we explored the effects of dietary indole-3-aldehyde (IAld), a key tryptophan metabolite, on intestinal development and gut barrier function in weaned piglets. Supplementation with 100 mg/kg IAld in the diet increased the small intestine index and improved intestinal barrier function by promoting intestinal stem cell (ISC) expansion in piglets. The promotion of ISC expansion by IAld was also confirmed in porcine intestinal organoids.ConclusionsThese findings revealed that intestinal microbial tryptophan metabolite IAld alleviates impaired intestinal development by promoting ISC expansion in weaned piglets.

Navigating contradictions: Salmonella Typhimurium chemotactic responses to conflicting effector stimuli.

Chemotaxis controls swimming motility and colonization of many intestinal bacteria, but how enteric pathogens navigate the complex chemical landscape of the gut, which contains contradictory chemoattractant and chemorepellent stimuli, remains poorly understood. We find Salmonella Typhimurium requires chemotactic sensing of two opposing signals present in the intestinal lumen-the microbiota metabolite and bacteriostatic chemorepellent indole, and the nutrient chemoattractant L-Ser-for efficient invasion of colonic tissue. Despite feces being the major biological source of indole, accumulating to millimolar levels, non-typhoidal Salmonella are strongly attracted to fecal material because chemoattraction to L-Ser and other attractants override indole chemorepulsion. This behavior is orchestrated through the chemoreceptor Tsr, which coordinates a spectrum of distinct rearrangements in the bacterial population structure based on the ratio of L-Ser to indole. Through seeking niches with the highest L-Ser to indole ratio, S. Typhimurium presumably optimizes nutrient access and avoids regions of high-competitor density.

Unveiling the Gut-Disc Axis: How Microbiome Dysbiosis Accelerates Intervertebral Disc Degeneration.

The gut microbiome (GM), often referred to as the second genome of the human body, plays a crucial role in various metabolic processes and mediates the development of numerous diseases. Intervertebral disc degeneration (IDD) is an age-related degenerative spinal disease characterized by the loss of disc height, hydration, and integrity, leading to pain and reduced mobility. Although the pathogenesis of IDD is not fully understood, recent studies suggest that dysbiosis of the gut microbiome may accelerate the progression of IDD through multiple mechanisms. This article begins by discussing the potential relationship between GM dysbiosis and human diseases, followed by a comprehensive review of the regulatory mechanisms of GM in skeletal diseases within the gut-disc axis framework. Furthermore, it explores three potential pathways through which GM dysbiosis may mediate the development of IDD: immunomodulation, bacterial translocation and colonization, and the decomposition and absorption of intestinal metabolites. These pathways can disrupt disc cell homeostasis and promote degenerative changes. Finally, this paper summarizes for the first time the potential therapeutic approaches for delaying IDD by targeting the gut-disc axis, providing new insights into the pathogenesis and regenerative repair strategies for IDD.

Intestinal microflora and metabolites affect the progression of acute pancreatitis (AP)

Specific intestinal metabolites are closely associated with the classification, severity, and necrosis of acute pancreatitis (AP) and provide novel insights for in-depth clinical investigations. In this study, the gut microbiota and metabolites of 49 AP patients at different treatment stages and severities were analysed via 16S rDNA sequencing and untargeted metabolomics to investigate the trends in gut microbiota composition and metabolome profiles observed in patients with severe AP. These findings revealed an imbalance in intestinal flora homeostasis among AP patients characterized by a decrease in probiotics and an increase in opportunistic pathogens, which leads to damage to the intestinal mucosal barrier through reduced short-chain fatty acid (SCFA) secretion and disruption of the intestinal epithelium. This dysbiosis influences energy metabolism, anti-inflammatory responses, and immune regulation, and these results highlight significant differences in energy metabolism pathways. These findings suggest that the differential composition of intestinal flora, along with alterations in intestinal metabolites and metabolic pathways, contribute to the compromised integrity of the intestinal mucosal barrier and disturbances in energy metabolism in patients with severe AP.

Gut microbiota and metabolic profile changes unveil the deterioration of alveolar bone inflammatory resorption with aging induced by D-galactose.

The global aging population has led to a rise in age-related health issues, such as malnutrition, metabolic disorders, and even immune decline. Among these concerns, periodontitis holds particular significance for the well-being of the elderly. This study aimed to investigate the impact of aging on inflammatory resorption of alveolar bone in mice with periodontitis, with a specific focus on alterations in the intestinal microenvironment. To achieve this, we established a D-galactose (D-gal)-induced aging mouse model with periodontitis and employed histopathological staining, oxidative stress, and inflammatory factors analyses to assess the severity of periodontitis and the health status. Additionally, the 16S rRNA sequencing and untargeted metabolomics analysis were employed to investigate alterations in the intestinal microbiota and metabolites. Our results showed that D-gal-induced aging mice with periodontitis experienced more pronounced alveolar bone inflammatory resorption and disruptions in the gut barrier, accompanied by an overall decline in physical condition. The microbial composition and structure of aged mice also underwent significant modifications, with a decreased Firmicutes/Bacteroidetes (F/B) ratio. Furthermore, metabolomics analysis demonstrated that D-gal-induced aging primarily influenced lipids and lipid-like molecules metabolism, and enrichment observed in the rheumatoid arthritis and histidine metabolism pathways. These findings provide further evidence that the aging process exacerbates age-related alveolar bone loss (ABL) through disturbances in intestinal homeostasis.

20 (S)-Protopanaxadiol Alleviates DRP1-Mediated Mitochondrial Dysfunction in a Depressive Model In Vitro and In Vivo via the SIRT1/PGC-1α Signaling Pathway.

Depression is a complex and common mental illness affecting physical and psychological health. Panax ginseng C. A. Mey is a traditional Chinese medicine with abundant pharmacological activity and applications in regulating mood disorders. 20 (S)-Protopanaxadiol is the major intestinal metabolite of ginsenoside and one of the active components in ginseng. In this study, we aimed to investigate the therapeutic effects of 20 (S)-Protopanaxadiol on neuronal damage and depression, which may involve mitochondrial dynamics. However, the mechanism underlying the antidepressant effects of 20 (S)-Protopanaxadiol is unelucidated. In the present study, we investigated the potential mechanisms underlying the antidepressant activity of 20 (S)-Protopanaxadiol by employing a corticosterone-induced HT22 cellular model and a chronic unpredicted mild stress (CUMS)-induced animal model in combination with a network pharmacology approach. In vitro, the results showed that 20 (S)-Protopanaxadiol ameliorated the corticosterone (CORT)-induced decrease in HT22 cell viability, decrease in 5-hydroxytryptamine (5-HT) levels, and increase in nitric oxide (NO) and malondialdehyde (MDA) levels. Furthermore, 20 (S)-Protopanaxadiol exerted improvement effects on the CORT-induced increase in HT22 cell mitochondrial reactive oxygen species, loss of mitochondrial membrane potential, and apoptosis. In vivo, the results showed that 20 (S)-Protopanaxadiol ameliorated depressive symptoms and hippocampal neuronal damage in CUMS mice, and sirtuin1 (SIRT1) and peroxisome proliferator-activated receptor-1-Alpha (PGC-1α) activity were activated in the hippocampus of mice, thereby alleviating mitochondrial dysfunction and promoting the clearance of damaged mitochondria. In both in vivo and in vitro models, after inhibiting SIRT1 expression, the protective effect of 20 (S)-Protopanaxadiol on mitochondria was significantly weakened, and dynamin-related protein 1 (DRP1)-mediated mitochondrial division was significantly reduced. These findings suggest that 20 (S)-Protopanaxadiol may exert neuroprotective and antidepressant effects by attenuating DRP1-mediated mitochondrial dysfunction and apoptosis by modulating the SIRT1/PGC-1α signaling pathway.

Aspirin inhibits atherosclerosis through macrophage pyroptosis by interacting with Lactobacillus johnsonii and its metabolite butyrate

Abstract Introduction Atherosclerotic cardiovascular disease (ASCVD) is a chronic progressive disease closely related to metabolism and inflammation. Aspirin inhibits cyclooxygenase (COX) and has antiplatelet aggregation effects, considered as the cornerstone of ASCVD treatment. Numerous studies have shown that gut microbiota (GM) and its metabolites affects host metabolism. Studies have also shown that people taking aspirin exhibit specific changes in the microbiota profile. However, whether the interaction of aspirin with GM and its metabolites affects the therapeutic efficacy of aspirin in treating atherosclerosis (AS) have not been reported. Purpose This study aimed to explore the interaction of aspirin with the GM and its metabolites in the treatment of AS, to reveal the specific mechanism of the GM-metabolite axis and provide potential new targets for the combined treatment of AS. Methods To establish the mouse model of atherosclerosis by high-fat diet, and the atherosclerotic plaque burden and composition were analyzed. The role of GM in aspirin anti-atherosclerosis was explored by antibiotics and fecal microbiota transplantation (FMT). The third generation 16S RNA sequencing was used to explore the effects of aspirin on species diversity and abundance of GM, and to screen differential microorganisms for intervention of AS mice. UHPLC-MS and GC-MS were used to explore the changes of intestinal metabolites induced by aspirin. The correlation between gut microbiota and metabolites was also investigated. Finally, in vitro and in vivo experiments were performed to confirm the effects and mechanisms of metabolites on macrophage pyroptosis and atherosclerosis. Results Aspirin has anti-atherosclerosis effect. After removing gut microbiota, the therapeutic effect of aspirin on atherosclerosis was decreased. Three generations of 16S rRNA gene sequencing results showed that aspirin supplementation alters the diversity of gut microbiota, and increased the relative abundance of Lactobacillus johnsonii(L.johnsonii) and Ligilactobacillus murinus(L.murinus). After gavage of L.johnsonii and L.murinus, the plaque burden and macrophage pyroptosis were significantly reduced in AS mice. Colonization with L.johnsonii and L.murinus significantly increased the abundance of probiotics and butyrate level in the feces of AS mice and L.johnsonii and L.murinus were positively correlated with butyrate. Supplementation of butyrate inhibited macrophage pyroptosis and atherosclerosis in vivo. In vitro, butyrate could inhibit the expression of NLRP3/Caspase-1/IL-1β and pyroptosome production, and this process mainly by activating butyrate receptors GPR41, GPR43 and GPR109A. Conclusions The gut microbiota may mediate the anti-AS effect of aspirin by promoting an increase in the abundance of L.johnsonii and L.murinus. Butyrate produced by Lactobacillus may mediate the anti-AS effect of aspirin, and inhibiting macrophage pyroptosis and the progression of AS.

IL-33 Induces a Switch in Intestinal Metabolites Revealing the Tryptophan Pathway as a Target for Inducing Allograft Survival.

IL-33, a pleiotropic cytokine, has been associated with a plethora of immune-related processes, both inflammatory and anti-inflammatory. T regulatory (Treg) cells, the main leukocyte population involved in immune tolerance, can be induced by the administration of IL-33, the local microbiota, and its metabolites. Here, we demonstrate that IL-33 drastically induces the production of intestinal metabolites involved on tryptophan (Trp) metabolism. naïve mice were treated with IL-33 for 4 days and leukocyte populations were analyzed by flow cytometry, and feces were processed for microbiota and intestinal metabolites studies. Using a murine skin transplantation model, the effect of Kynurenic acid (KA) on allograft survival was tested. Under homeostatic conditions, animals treated with IL-33 showed an increment in Treg cell frequencies. Intestinal bacterial abundance analysis indicates that IL-33 provokes dysbiosis, demonstrated by a reduction in Enterobacteria and an increment in Lactobacillus genera. Furthermore, metabolomics analysis showed a dramatic IL-33 effect on the abundance of intestinal metabolites related to amino acid synthesis pathways, highlighting molecules linked to Trp metabolism, such as kynurenic acid (KA), 5-Hydroxyindoleacetic acid (5-HIAA), and 6-Hydroxynicotinic acid (6-HNA), which was supported by an enhanced expression of Ido and Kat mRNA in MLN cells, which are two enzymes involved on KA synthesis. Interestingly, animals receiving KA in drinking water and subjected to skin transplantation showed allograft acceptance, which is associated with an increment in Treg cell frequencies. Our study reveals a new property for IL-33 as a modulator of the intestinal microbiota and metabolites, especially those involved with Trp metabolism. In addition, we demonstrate that KA favors Tregs in vivo, positively affecting skin transplantation survival.

Daikenchuto, a Japanese herbal medicine, ameliorates experimental colitis in a murine model by inducing secretory leukocyte protease inhibitor and modulating the gut microbiota.

Inflammatory bowel disease (IBD) is a refractory inflammatory disorder of the intestine, which is probably triggered by dysfunction of the intestinal epithelial barrier. Secretory leukocyte protease inhibitor (SLPI) secreted by colon epithelial cells protects against intestinal inflammation by exerting anti-protease and anti-microbial activities. Daikenchuto (DKT) is one of the most commonly prescribed Japanese traditional herbal medicines for various digestive diseases. Although several animal studies have revealed that DKT exerts anti-inflammatory effects, its detailed molecular mechanism is unclear. This study aimed to clarify the anti-inflammatory mechanism of DKT using a murine colitis model, and to evaluate its potential as a therapeutic agent for IBD. Experimental colitis was induced in wild-type (WT) mice and SLPI-deficient (KO) mice by dextran sulfate sodium (DSS) after oral administration of DKT. The resultant clinical symptoms, histological changes, and pro-inflammatory cytokine levels in the colon were assessed. Expression of SLPI in the colon was detected by Western blotting and immunohistochemistry. Composition of the gut microbiota was analyzed by 16S rRNA metagenome sequencing and intestinal metabolites were measured by gas chromatography-mass spectrometry analysis. Intestinal epithelial barrier function was assessed by oral administration of FITC-dextran and immunostaining of tight junction proteins (TJPs). Oral administration of DKT increased the number of butyrate-producing bacteria, such as Parabacteroides, Allobaculum, and Akkermansia, enhanced the levels of short-chain fatty acids, including butyrate, in the colon, induced SLPI expression, and ameliorated DSS-induced colitis in WT mice. We found that mouse colon carcinoma cell line treatment with either DKT or butyrate significantly enhanced the expression of SLPI. Moreover, supplementation of DKT protected the intestinal epithelial barrier with augmented expression of TJPs in WT mice, but not in KO mice. Finally, the composition of the gut microbiota was changed by DKT in WT mice, but not in KO mice, suggesting that DKT alters the colonic bacterial community in an SLPI-dependent manner. These results indicate that DKT exerts anti-inflammatory effects on the intestinal epithelial barrier by SLPI induction, due, at least in part, to increased butyrate-producing bacteria and enhanced butyrate levels in the colon. These results provide insight into the mechanism of the therapeutic effects of DKT on IBD.

Angiotensin-(1-7) improves intestinal microbiota disturbances and modulates fecal metabolic aberrations in acute pancreatitis.

Acute pancreatitis (AP) is a serious health problem that dysregulates intestinal microbiota. Angiotensin (Ang)-(1-7) plays a protective role in the intestinal barrier in AP, but its effect on intestinal microbiota remains clear. To investigate the impact of Ang-(1-7) on AP-induced intestinal microbiota disorder and metabolites. We collected blood and fecal samples from 31 AP patients within 48 h after admission to the hospital, including 11 with mild AP (MAP), 14 with moderately severe AP (MSAP), six with severe AP (SAP). Mice were divided into four groups: control, AP, AP + Ang-(1-7) via tail vein injection, and AP + Ang-(1-7) via oral administration. The samples of mice were collected 12 h after AP. Pancreatic and intestinal histopathology scores were analyzed using the Schmidt and Chiu scores. Fecal microbiota and metabolites analysis was performed via 16S rDNA sequencing and nontargeted metabolomics analysis, respectively. In patients, the abundance of beneficial bacteria (Negativicutes) decreased and pathogenic bacteria (Clostridium bolteae and Ruminococcus gnavus) increased in SAP compared with MAP. Ang-(1-7) levels were associated with changes in the microbiota. There were differences in the intestinal microbiota between control and AP mice. Ang-(1-7) attenuated intestinal microbiota dysbiosis in AP mice, reflecting in the increase in beneficial bacteria (Odoribacter and Butyricimonas) than AP, as well as pancreatic and intestinal injuries. Oral administration of Ang-(1-7) reversing AP-induced decreases in metabolisms: secondary bile acids, emodin, and naringenin. Ang-(1-7) may improve intestinal microbiota dysbiosis and modulate fecal metabolites in AP, thereby reducing the damage of AP.

The gut-eye axis: from brain neurodegenerative diseases to age-related macular degeneration.

Age-related macular degeneration Is a serious neurodegenerativo disease of the retina that significantly impacts vision. Unfortunately, the specific pathogenesis remains unclear, and effective early treatment options are consequently lacking. The microbiome is defined as a large ecosystem of microorganisms living within and coexisting with a host. The intestinal microbiome undergoes dynamic changes owing to age, diet, genetics, and other factors. Such dysregulation of the intestinal flora can disrupt the microecological balance, resulting in immunological and metabolic dysfunction in the host, and affecting the development of many diseases. In recent decades, significant evidence has indicated that the intestinal flora also influences systems outside of the digestive tract, including the brain. Indeed, several studies have demonstrated the critical role of the gut-brain axis in the development of brain neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Similarly, the role of the "gut-eye axis" has been confirmed to play a role in the pathogenesis of many ocular disorders. Moreover, age-related macular degeneration and many brain neurodegenerative diseases have been shown to share several risk factors and to exhibit comparable etiologies. As such, the intestinal flora may play an important role in age-related macular degeneration. Given the above context, the present review aims to clarify the gut-brain and gut-eye connections, assess the effect of intestinal flora and metabolites on age-related macular degeneration, and identify potential diagnostic markers and therapeutic strategies. Currently, direct research on the role of intestinal flora in age-related macular degeneration is still relatively limited, while studies focusing solely on intestinal flora are insufficient to fully elucidate its functional role in age-related macular degeneration. Organ-on-a-chip technology has shown promise in clarifying the gut-eye interactions, while integrating analysis of the intestinal flora with research on metabolites through metabolomics and other techniques is crucial for understanding their potential mechanisms.