Butyrate and glucose metabolism by colonocytes in experimental colitis in mice

Gut Metagenome Reveals the Microbiome Signatures in Tibetan and Black Pigs

The harsh conditions of the Qinghai-Tibet Plateau pose significant physiological challenges to local fauna, often resulting in gastrointestinal disorders. However, Tibetan pigs have exhibited remarkable adaptability to the high-altitude stress of the Tibetan Plateau, a phenomenon that remains not fully understood in terms of their gastrointestinal microbiota. This study collected 57 gastrointestinal tract samples from Tibetan pigs (n = 6) and plain black pigs (n = 6) with comparable genetic backgrounds. Samples from the stomach, jejunum, cecum, colon, and rectum, underwent comprehensive metagenomic analysis to elucidate the gut microbiota-related adaptive mechanisms in Tibetan pigs to the extreme high-altitude environment. A predominance of Pseudomonadota was observed within gut microbiome of Tibetan pigs. Significant differences in the microbial composition were also identified across the tested gastrointestinal segments, with 18 genera and 141 species exhibiting differential abundance. Genera such as Bifidobacterium, Megasphaera, Fusobacterium, and Mitsuokella were significantly more abundant in Tibetan pigs than in their lowland counterparts, suggesting specialized adaptations. Network analysis found greater complexity and modularity in the microbiota of Tibetan pigs compared to black pigs, indicating enhanced ecological stability and adaptability. Functional analysis revealed that the Tibetan pig microbiota was particularly enriched with bacterial species involved in metabolic pathways for propionate and butyrate, key short-chain fatty acids that support energy provision under low-oxygen conditions. The enzymatic profiles of Tibetan pigs, characterized by elevated levels of 4-hydroxybutyrate dehydrogenase and glutaconyl-CoA decarboxylase, highlighted a robust fatty acid metabolism and enhanced tricarboxylic acid cycle activity. In contrast, the gut microbiome of plain black pigs showed a reliance on the succinate pathway, with a reduced butyrate metabolism and lower metabolic flexibility. Taken together, these results demonstrate the crucial role of the gastrointestinal microbiota in the adaptation of Tibetan pigs to high-altitude environments by optimizing carbohydrate metabolism and short-chain fatty acid production for efficient energy utilization. This study not only highlights the metabolic benefits conferred by the gut microbiota of Tibetan pigs in extreme environments, but also advances our understanding of the adaptive gastrointestinal mechanisms in plateau-dwelling animals. These insights lay the foundation for exploring metabolic interventions to support health and performance in high-altitude conditions.

A potential therapeutic approach for ulcerative colitis: targeted regulation of mitochondrial dynamics and mitophagy through phytochemicals

Mitochondria are important organelles that regulate cellular energy and biosynthesis, as well as maintain the body's response to environmental stress. Their dynamics and autophagy influence occurrence of cellular function, particularly under stressful conditions. They can generate reactive oxygen species (ROS) which is a major contributor to inflammatory diseases such as ulcerative colitis (UC). In this review, we discuss the key effects of mitochondrial dynamics and mitophagy on the pathogenesis of UC, with a particular focus on the cellular energy metabolism, oxidative stress, apoptosis, and immunoinflammatory activities. The therapeutic efficacy of existing drugs and phytochemicals targeting the mitochondrial pathway are discussed to reveal important insights for developing therapeutic strategies for treating UC. In addition, new molecular checkpoints with therapeutic potential are identified. We show that the integration of mitochondrial biology with the clinical aspects of UC may generate ideas for enhancing the clinical management of UC.

Sodium Butyrate, A Gut Microbiota Derived Metabolite in Type 2 Diabetes Mellitus and Cardiovascular Disease: A Review

Type 2 diabetes is characterized by elevated blood glucose levels, leading to an increased risk of cardiovascular diseases. Sodium butyrate, the sodium salt of the short-chain fatty acid butyric acid produced by gut microbiota fermentation, has shown promising effects on metabolic diseases, including type 2 diabetes and cardiovascular diseases. Sodium butyrate demonstrates anti-inflammatory, anti-oxidative, and lipid-lowering properties and can improve insulin sensitivity and reduce hepatic steatosis. In this review, we investigate how sodium butyrate influences cardiovascular complications of type 2 diabetes, including atherosclerosis (AS), heart failure (HF), hypertension, and angiogenesis. Moreover, we explore the pathophysiology of cardiovascular disease in type 2 diabetes, focusing on hyperglycemia, oxidative stress, inflammation, and genetic factors playing crucial roles. The review suggests that sodium butyrate can be a potential preventive and therapeutic agent for cardiovascular complications in individuals with type 2 diabetes.

Effects of xylo-oligosaccharide supplementation on the production performance, intestinal morphology, cecal short-chain fatty acid levels, and gut microbiota of laying hens

This study investigated the effects of xylo-oligosaccharide supplementation on the production performance, intestinal morphology, cecal short-chain fatty acid levels, and gut microbiota of laying hens. A total of 800 Lohmann pink layers, each 48 wk old, were randomly divided into 5 dietary treatment groups, namely XOS at 0 (CON), 100 (XOS1), 200 (XOS2), 300 (XOS3) and 400 (X0S4) mg/kg. The experimental period was 24 wk. The results revealed that the egg production rate and the number of eggs laid by each layer between 1 to 12 wk increased as the XOS concentration increased (Plinear < 0.05). The sand-shell egg percentage decreased significantly from 1 to 12 wk in the XOS1, XOS2, and XOS3 groups (PANOVA < 0.05). Compared with the CON group, the 4 XOS dosage groups presented significant increases in the villus height and the ratio of villus height to crypt depth in the jejunum (PANOVA < 0.05), whereas a linear decrease in jejunal crypt depth (Plinear < 0.05) was noted. In addition, XOS supplementation significantly increased the concentrations of butyric acid and isovaleric acid in the caeca (PANOVA < 0.05). High-throughput sequencing analysis of bacterial 16S rRNA revealed that dietary XOS supplementation influenced the cecal microbiota. The alpha diversity analysis indicated that the richness of cecal bacteria was greater in the laying hens fed XOS. The modulation of the cecal microbiota composition upon the addition of XOS was characterized by an increased abundance of Firmicutes and Bifidobacteriaceae, and decreased abundance of Bacteroidetes. At the genus level, dietary XOS supplementation resulted in decreases in the abundances of Bacteroides and Rikenellaceae_RC9_gut_group and an increase in the abundance of Lactobacillus. In conclusion, dietary XOS supplementation improved the production performance of laying hens by increasing the production of short-chain fatty acids and improving their intestinal morphology, which was achieved mainly through changes in the composition of the intestinal microbiota. The recommended level of XOS in the diet of laying hens is 200 mg/kg.

The role of the mucosal barrier system in maintaining gut symbiosis to prevent intestinal inflammation

In the intestinal tract, where numerous intestinal bacteria reside, intestinal epithelial cells produce and release various antimicrobial molecules that form a complex barrier on the mucosal surface. These barrier molecules can be classified into two groups based on their functions: those that exhibit bactericidal activity through chemical reactions, such as antimicrobial peptides, and those that physically hinder bacterial invasion, like mucins, which lack bactericidal properties. In the small intestine, where Paneth cells specialize in producing antimicrobial peptides, the chemical barrier molecules primarily inhibit bacterial growth. In contrast, in the large intestine, where Paneth cells are absent, allowing bacterial growth, the primary defense mechanism is the physical barrier, mainly composed of mucus, which controls bacterial movement and prevents their invasion of intestinal tissues. The expression of these barrier molecules is regulated by metabolites produced by bacteria in the intestinal lumen and cytokines produced by immune cells in the lamina propria. This regulation establishes a defense mechanism that adapts to changes in the intestinal environment, such as alterations in gut microbial composition and the presence of pathogenic bacterial infections. Consequently, when the integrity of the gut mucosal barrier is compromised, commensal bacteria and pathogenic microorganisms from outside the body can invade intestinal tissues, leading to conditions such as intestinal inflammation, as observed in cases of inflammatory bowel disease.

Host-diet-microbiota interplay in intestinal nutrition and health

The intestine is populated by a complex and dynamic assortment of microbes, collectively called gut microbiota, that interact with the host and contribute to its metabolism and physiology. Diet is considered a key regulator of intestinal microbiota, as ingested nutrients interact with and shape the resident microbiota composition. Furthermore, recent studies underscore the interplay of dietary and microbiota-derived nutrients, which directly impinge on intestinal stem cells regulating their turnover to ensure a healthy gut barrier. Although advanced sequencing methodologies have allowed the characterization of the human gut microbiome, mechanistic studies assessing diet-microbiota-host interactions depend on the use of genetically tractable models, such as Drosophila melanogaster. In this review, we first discuss the similarities between the human and fly intestines and then we focus on the effects of diet and microbiota on nutrient-sensing signaling cascades controlling intestinal stem cell self-renewal and differentiation, as well as disease. Finally, we underline the use of the Drosophila model in assessing the role of microbiota in gut-related pathologies and in understanding the mechanisms that mediate different whole-body manifestations of gut dysfunction.

Sustainable biorefinery approach by utilizing xylose fraction of lignocellulosic biomass

Lignocellulosic biomass (LCB) has been a lucrative feedstock for developing biochemical products due to its rich organic content, low carbon footprint and abundant accessibility. The recalcitrant nature of this feedstock is a foremost bottleneck. It needs suitable pretreatment techniques to achieve a high yield of sugar fractions such as glucose and xylose with low inhibitory components. Cellulosic sugars are commonly used for the bio-manufacturing process, and the xylose sugar, which is predominant in the hemicellulosic fraction, is rejected as most cell factories lack the five‑carbon metabolic pathways. In the present review, more emphasis was placed on the efficient pretreatment techniques developed for disintegrating LCB and enhancing xylose sugars. Further, the transformation of the xylose to value-added products through chemo-catalytic routes was highlighted. In addition, the review also recapitulates the sustainable production of biochemicals by native xylose assimilating microbes and engineering the metabolic pathway to ameliorate biomanufacturing using xylose as the sole carbon source. Overall, this review will give an edge on the bioprocessing of microbial metabolism for the efficient utilization of xylose in the LCB.

Enhancement of intestinal calcium transport by short-chain fatty acids: roles of Na+/H+ exchanger 3 and transient receptor potential vanilloid subfamily 6

Small organic molecules in the intestinal lumen, particularly short-chain fatty acids (SCFAs) and glucose, have long been postulated to enhance calcium absorption. Here, we used 45Ca radioactive tracer to determine calcium fluxes across the rat intestine after exposure to glucose and SCFAs. Confirming previous reports, glucose was found to increase the apical-to-basolateral calcium flux in the cecum. Under apical glucose-free conditions, SCFAs (e.g., butyrate) stimulated the cecal calcium fluxes by approximately twofold, while having no effect on proximal colon. Since SCFAs could be absorbed into the circulation, we further determined whether basolateral SCFA exposure rendered some positive actions. It was found that exposure of duodenum and cecum on the basolateral side to acetate or butyrate increased calcium fluxes. Under butyrate-rich conditions, cecal calcium transport was partially diminished by Na+/H+ exchanger 3 (NHE3) inhibitor (tenapanor) and nonselective transient receptor potential vanilloid subfamily 6 (TRPV6) inhibitor (miconazole). To confirm the contribution of TRPV6 to SCFA-stimulated calcium transport, we synthesized another TRPV6 inhibitor that was demonstrated by in silico molecular docking and molecular dynamics to occlude TRPV6 pore and diminish the glucose- and butyrate-induced calcium fluxes. Therefore, besides corroborating the importance of luminal molecules in calcium absorption, our findings provided foundation for development of more effective calcium-rich nutraceuticals in combination with various absorptive enhancers, e.g., glucose and SCFAs.NEW & NOTEWORTHY Organic molecules in the intestinal lumen, e.g., glucose and short-chain fatty acids (SCFAs), the latter of which are normally produced by microfloral fermentation, can stimulate calcium absorption dependent on transient receptor potential vanilloid subfamily 6 (TRPV6) and Na+/H+ exchanger 3 (NHE3). A selective TRPV6 inhibitor synthesized and demonstrated by in silico docking and molecular dynamics to specifically bind to the pore domain of TRPV6 was used to confirm a significant contribution of this channel. Our findings corroborate physiological significance of nutrients and SCFAs in enhancing calcium absorption.

Unraveling the gut health puzzle: exploring the mechanisms of butyrate and the potential of High-Amylose Maize Starch Butyrate (HAMSB) in alleviating colorectal disturbances

Colorectal disturbances encompass a variety of disorders that impact the colon and rectum, such as colitis and colon cancer. Butyrate, a short-chain fatty acid, plays a pivotal role in supporting gut health by nourishing colonocytes, promoting barrier function, modulating inflammation, and fostering a balanced microbiome. Increasing colorectal butyrate concentration may serve as a critical strategy to improve colon function and reduce the risk of colorectal disturbances. Butyrylated high-amylose maize starch (HAMSB) is an edible ingredient that efficiently delivers butyrate to the colon. HAMSB is developed by esterifying a high-amylose starch backbone with butyric anhydride. With a degree of substitution of 0.25, each hydroxy group of HAMSB is substituted by a butyryl group in every four D-glucopyranosyl units. In humans, the digestibility of HAMSB is 68% (w/w), and 60% butyrate molecules attached to the starch backbone is absorbed by the colon. One clinical trial yielded two publications, which showed that HAMSB significantly reduced rectal O6-methyl-guanine adducts and epithelial proliferation induced by the high protein diet. Fecal microbial profiles were assessed in three clinical trials, showing that HAMSB supplementation was consistently linked to increased abundance of Parabacteroides distasonis. In animal studies, HAMSB was effective in reducing the risk of diet- or AOM-induced colon cancer by reducing genetic damage, but the mechanisms differed. HAMSB functioned through affecting cecal ammonia levels by modulating colon pH in diet-induced cancer, while it ameliorated chemical-induced colon cancer through downregulating miR19b and miR92a expressions and subsequently activating the caspase-dependent apoptosis. Furthermore, animal studies showed that HAMSB improved colitis via regulating the gut immune modulation by inhibiting histone deacetylase and activating G protein-coupled receptors, but its role in bacteria-induced colon colitis requires further investigation. In conclusion, HAMSB is a food ingredient that may deliver butyrate to the colon to support colon health. Further clinical trials are warranted to validate earlier findings and determine the minimum effective dose of HAMSB.

An Inflammatory Bowel Diseases Integrated Resources Portal (IBDIRP)

IBD, including ulcerative colitis and Crohn's disease, is a chronic and debilitating gastrointestinal disorder that affects millions of people worldwide. Research on IBD has generated massive amounts of data, including literature, metagenomics, metabolomics, bioresources and databases. We aim to create an IBD Integrated Resources Portal (IBDIRP) that provides the most comprehensive resources for IBD. An integrated platform was developed that provides information on different aspects of IBD research resources, such as single-nucleotide polymorphisms (SNPs), genes, transcriptome, microbiota, metabolomics, single cells and other resources. Valuable and comprehensive IBD-related data were collected from PubMed, Google, GMrepo, gutMega, gutMDisorder, Single Cell Portal and other sources. Then, the data were systematically sorted, and these resources were manually curated. We systematically sorted and cataloged more than 320 unique risk SNPs associated with IBD in the SNP section. We presented over 289 IBD-related genes based on the database collection in the gene section. We also obtained 153 manually curated IBD transcriptomics data, including 12 388 samples, on the Gene Expression Omnibus database. The sorted IBD-related microbiota data from three primary microbiome databases (GMrepo, gutMega and gutMDisorder) were available for download. We selected 23 149 IBD-related taxonomic records from these databases. Additionally, we collected 24 IBD metabolomics studies with 2896 participants in the metabolomics section. We introduced two interactive single-cell data plug-in units that provided data visualization based on cells and genes. Finally, we listed 18 significant IBD web resources, such as the official European Crohn's and Colitis Organisation and International Organization for the Study of IBD websites, IBD scoring tools, IBD genetic and multi-omics resources, IBD biobanks and other useful research resources. The IBDIRP website is the first integrated resource for global IBD researchers. This portal will help researchers by providing comprehensive knowledge and enabling them to reinforce the multidimensional impression of IBD. The IBDIRP website is accessible via www.ibdirp.com Database URL: www.ibdirp.com.

Similarities and Differences of Vascular Calcification in Diabetes and Chronic Kidney Disease

Presently, the mechanism of occurrence and development of vascular calcification (VC) is not fully understood; a range of evidence suggests a positive association between diabetes mellitus (DM) and VC. Furthermore, the increasing burden of central vascular disease in patients with chronic kidney disease (CKD) may be due, at least in part, to VC. In this review, we will review recent advances in the mechanisms of VC in the context of CKD and diabetes. The study further unveiled that VC is induced through the stimulation of pro-inflammatory factors, which in turn impairs endothelial function and triggers similar mechanisms in both disease contexts. Notably, hyperglycemia was identified as the distinctive mechanism driving calcification in DM. Conversely, in CKD, calcification is facilitated by mechanisms including mineral metabolism imbalance and the presence of uremic toxins. Additionally, we underscore the significance of investigating vascular alterations and newly identified molecular pathways as potential avenues for therapeutic intervention.

Inulin Supplementation Modulates the Hepatic Transcriptome, Metabolome, and Ferritin Content in Ovariectomized Rats

SCOPE

Liver is an important metabolic organ regulating whole-body homeostasis. This study aims to investigate how prebiotic-induced changes in the metabolic activity of the gut microbiome (GM) and dietary calcium depletion modulates the hepatic metabolome and transcriptome.

METHODS AND RESULTS

The serum metabolome, liver metabolome, and transcriptome are determined on samples from ovariectomized (OVX) rats fed a control diet (Control, n = 7), a control diet supplemented with 5% w/w inulin (Inulin, n = 7), or a calcium-deficient diet (CaDef, n = 7). Inulin fortification is associated with higher serum concentrations of acetate, 3-hydroxybutyrate, and reduced concentration of dimethyl sulfone, revealing that changes in the metabolic activity of the GM are reflected in circulating metabolites. Metabolomics also reveal that the inulin-fortified diet results in lower concentrations of hepatic glutamate, serine, and hypoxanthine while transcriptomics reveal accompanying effects on the hepatic expression of ferric iron binding-related genes. Inulin fortification also induces effects on the hepatic expression of genes involved in olfactory transduction, suggesting that prebiotics regulate liver function through yet unidentified mechanisms involving olfactory receptors.

CONCLUSION

Inulin ingestion impacts hepatic gene expression and is associated with an upregulation of ferritin synthesis-related genes and liver ferritin content.

Gut dysbiosis-related thrombosis in inflammatory bowel disease: Potential disease mechanisms and emerging therapeutic strategies

Patients with inflammatory bowel disease (IBD) have an increased risk of developing venous thromboembolic events, which have a considerable impact on morbidity and mortality. Chronic inflammation plays a crucial role in the pathogenesis of thrombotic events in patients with IBD. However, many unresolved questions remain, particularly regarding the mechanisms that determine the persistent inflammatory state independent of disease activity. This review explored the role of gut microbiota dysbiosis and intestinal barrier dysfunction, which are considered distinctive features of IBD, in determining pro-thrombotic tendencies. Gut-derived endotoxemia due to the translocation of bacterial lipopolysaccharides (LPS) from the intestine to the bloodstream and the bacterial metabolite trimethylamine-N-oxide (TMAO) are the most important molecules involved in gut dysbiosis-related thrombosis. The pathogenic prothrombotic pathways linked to LPS and TMAO have been discussed. Finally, we present emerging therapeutic approaches that can help reduce LPS-mediated endotoxemia and TMAO, such as restoring intestinal eubiosis, normalizing intestinal barrier function, and counterbalancing the effects of LPS and TMAO.

Effects of gut microbiota on prostatic cancer: a two-sample Mendelian randomization study

Aim

Recent observational and small-sample case-control studies have shown a relationship between gut microbiota composition and prostatic cancer (PCa). Nevertheless, the causal association between gut microbiota and PCa is still unclear. Herein, we used the Mendelian randomization (MR) method to explore the potential causal relationship between gut microbiota and PCa.

Methods

In this two-sample MR study, data were extracted from the summary statistics of gut microbiota from the largest available genome-wide association study meta-analysis conducted by the MiBioGen consortium (n = 14,306) and the Dutch Microbiome Project (n = 8,208). Summary statistics for PCa were obtained from the FinnGen consortium release data (n = 95,213). Inverse variance weighted (IVW), MR-Egger, strength test (F), and MR-PRESSO were used to examine the potential causal association between gut microbiota and PCa. Cochran's Q statistics were used to quantify the heterogeneity of instrumental variables.

Results

IVW estimates suggested that the relative abundance of Akkermansia muciniphila (odds ratio [OR] = 0.7926, 95% confidence interval [CI]: 0.6655-0.9440) and Bacteroides salyersiae (OR = 0.9023, 95% CI: 0.8262-0.9853) were negatively associated with the odds of PCa, while that of Eubacterium biforme (OR = 1.1629, 95% CI: 1.0110-1.3376) was positively associated with the odds of PCa. In addition, we explored these relationships among patients without other cancers and similarly found that the relative abundance of Akkermansia muciniphila, Bacteroides salyersiae, and Eubacterium biforme were linked to PCa (all P < 0.05).

Conclusion

Gut microbiota potentially influenced the occurrence of PCa. Our findings may provide some new ideas for researching the methods of PCa prevention. In addition, further studies are needed to explore the causal association and specific underlying mechanisms between gut microbiota and PCa.

Exploring the gut microbiota: lifestyle choices, disease associations, and personal genomics

The gut microbiota is a rich and dynamic ecosystem that actively interacts with the human body, playing a significant role in the state of health and disease of the host. Diet, exercise, mental health, and other factors have exhibited the ability to influence the gut bacterial composition, leading to changes that can prevent and improve, or favor and worsen, both intestinal and extra-intestinal conditions. Altered gut microbial states, or 'dysbiosis', associated with conditions and diseases are often characterized by shifts in bacterial abundance and diversity, including an impaired Firmicutes to Bacteroidetes ratio. By understanding the effect of lifestyle on the gut microbiota, personalized advice can be generated to suit each individual profile and foster the adoption of lifestyle changes that can both prevent and ameliorate dysbiosis. The delivery of effective and reliable advice, however, depends not only on the available research and current understanding of the topic, but also on the methods used to assess individuals and to discover the associations, which can introduce bias at multiple stages. The aim of this review is to summarize how human gut microbial variability is defined and what lifestyle choices and diseases have shown association with gut bacterial composition. Furthermore, popular methods to investigate the human gut microbiota are outlined, with a focus on the possible bias caused by the lack of use of standardized methods. Finally, an overview of the current state of personalized advice based on gut microbiota testing is presented, underlining its power and limitations.

Mitochondrial remodeling and energy metabolism adaptations in colonic crypts during spontaneous epithelial repair after colitis induction in mice

Mucosal healing has emerged as a therapeutic goal to achieve lasting clinical remission in ulcerative colitis. Intestinal repair in response to inflammation presumably requires higher energy supplies for the restoration of intestinal barrier and physiological functions. However, epithelial energy metabolism during intestinal mucosal healing has been little studied, whereas inflammation-induced alterations have been reported in the main energy production site, the mitochondria. The aim of the present work was to assess the involvement of mitochondrial activity and the events influencing their function during spontaneous epithelial repair after colitis induction in mouse colonic crypts. The results obtained show adaptations of colonocyte metabolism during colitis to ensure maximal ATP production for supporting energetic demand by both oxidative phosphorylation and glycolysis in a context of decreased mitochondrial biogenesis and through mitochondrial function restoration during colon epithelial repair. In parallel, colitis-induced mitochondrial ROS production in colonic epithelial cells was rapidly associated with transient expression of GSH-related enzymes. Mitochondrial respiration in colonic crypts was markedly increased during both inflammatory and recovery phases despite decreased expression of several mitochondrial respiratory chain complex subunits after colitis induction. Rapid induction of mitochondrial fusion was associated with mitochondrial function restoration. Finally, in contrast with the kinetics expression of genes involved in mitochondrial oxidative metabolism and in glycolysis, the expression of glutaminase was markedly reduced in the colonic crypts both during colitis and repair phases. Overall, our data suggest that the epithelial repair after colitis induction is characterized by a rapid and transient increased capacity for mitochondrial ATP production in a context of apparent restoration of mitochondrial biogenesis and metabolic reorientation of energy production. The potential implication of energy production adaptations within colonic crypts to sustain mucosal healing in a context of altered fuel supply is discussed.

Diet as a modifiable factor in tumorigenesis: Focus on microbiome-derived bile acid metabolites and short-chain fatty acids

Several lines of evidences have implicated the resident microbiome as a key factor in the modulation of host physiology and pathophysiology; including the resistance to cancers. Gut microbiome heavily influences host lipid homeostasis by their modulatory effects on the metabolism of bile acids (BAs). Microbiota-derived BA metabolites such as deoxycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) are implicated in the pathogeneses of various cancer types. The pathogenic mechanisms are multimodal in nature, with widespread influences on the host immunes system, cell survival and growth signalling and DNA damage. On the other hand, short-chain fatty acids (SCFAs) produced by the resident microbial activity on indigestible dietary fibres as well as during intermittent fasting regimens (such as the Ramazan fasting) elicit upregulation of the beneficial anti-inflammatory and anticancer pathways in the host. The present review first provides a brief overview of the molecular mechanisms of microbiota-derived lipid metabolites in promotion of tumour development. The authors then discuss the potential of diet as a therapeutic route for beneficial alteration of microbiota and the consequent changes in the production of SCFAs, particularly butyrate, in relation to the cancer prevention and treatment.

HIV, opioid use, and alterations to the gut microbiome: elucidating independent and synergistic effects

Background

The microbiome is essential to immune development, defense against pathogens, and modulation of inflammation. Microbial dysbiosis has been reported in various diseases including human immunodeficiency virus (HIV) and opioid use disorder (OUD). Notably, people living with HIV (PLWH) have been reported to both have higher rates of OUD and use opioids at higher rates than the general public. Thus, studying gut microbial alterations in people living with HIV and with OUD could elucidate mechanisms pertaining to how these conditions both shape and are shaped by the microbiome. However, to date few studies have investigated how HIV and OUD in combination impact the microbiome.

Aim of review

Here, we review previous studies outlining interactions between HIV, opioid use, and microbial dysbiosis and describe attempts to treat this dysbiosis with fecal microbial transplantation, probiotics, and dietary changes.

Key scientific concepts of review

While the limited number of studies prevent overgeneralizations; accumulating data suggest that HIV and opioid use together induce distinct alterations in the gut microbiome. Among the three existing preclinical studies of HIV and opioid use, two studies reported a decrease in Lachnospiraceae and Ruminococcaceae, and one study reported a decrease in Muribaculaceae in the combined HIV and opioid group relative to HIV-alone, opioid-alone, or control groups. These bacteria are known to modulate immune function, decrease colonic inflammation, and maintain gut epithelial barrier integrity in healthy individuals. Accordingly, modulation of the gut microbiome to restore gut homeostasis may be attempted to improve both conditions. While mixed results exist regarding treating dysbiosis with microbial restoration in PLWH or in those with opioid dependency, larger well-defined studies that can improve microbial engraftment in hosts hold much promise and should still be explored.

Composition of the gut microbiota in patients with inflammatory bowel disease in Saudi Arabia: A pilot study

CONCLUSIONS

The results of this study provide an overview of the variations in microbiota diversity present in Saudi IBD patients compared to healthy controls.

RESULTS

The key finding was three negative bacterial biomarkers, Paraprevotellaceae, the Muribaculaceae families of Bacteroidetes phylum, and the Leuconostocaceae family of Firmicutes phylum, which had a higher relative abundance in healthy individuals compared to IBD patients. It was also found that primary microbiota signatures at certain genera and species levels, including Prevotella copri, Bifidobacterium adolescentis, Ruminococcus callidus, Coprococcus sp., Ruminococcus gnavus, Dorea formicigenerans, Leuconostoc, Dialister, Catenibacterium, Eubacterium biforme, and Lactobacillus mucosae, were absent in almost all IBD patients, while Veillonella dispar was absent in all healthy individuals.

METHODS

After obtaining an informed consent, fecal samples were collected from 11 participants with IBD (patients) and 10 healthy individuals (controls). The bacterial components of the microbial population were identified by next-generation sequencing of partial 16S rRNA. Statistically significant dissimilarities were observed between samples for all metrics.

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition attributed to a complex interaction between imbalances in the gut microbiome, environmental conditions, and a deregulated immune response. The aim of the study was to investigate the composition of the gut microbiome of Saudi patients with IBD.

Stable isotope tracing in vivo reveals a metabolic bridge linking the microbiota to host histone acetylation

The gut microbiota influences acetylation on host histones by fermenting dietary fiber into butyrate. Although butyrate could promote histone acetylation by inhibiting histone deacetylases, it may also undergo oxidation to acetyl-coenzyme A (CoA), a necessary cofactor for histone acetyltransferases. Here, we find that epithelial cells from germ-free mice harbor a loss of histone H4 acetylation across the genome except at promoter regions. Using stable isotope tracing in vivo with 13C-labeled fiber, we demonstrate that the microbiota supplies carbon for histone acetylation. Subsequent metabolomic profiling revealed hundreds of labeled molecules and supported a microbial contribution to host fatty acid metabolism, which declined in response to colitis and correlated with reduced expression of genes involved in fatty acid oxidation. These results illuminate the flow of carbon from the diet to the host via the microbiota, disruptions to which may affect energy homeostasis in the distal gut and contribute to the development of colitis.

Butyrate reduces cellular magnesium absorption independently of metabolic regulation in Caco-2 human colon cells

Digestion of dietary fibers by gut bacteria has been shown to stimulate intestinal mineral absorption [e.g., calcium (Ca²⁺) and magnesium (Mg²⁺)]. Although it has been suggested that local pH and short-chain fatty acid (SCFA) concentrations determine divalent cation absorption, the exact molecular mechanisms are still unknown. Therefore, this study aimed to determine the effects of SCFAs on intestinal Mg²⁺ absorption. We show that the butyrate concentration in the colon negatively correlates with serum Mg²⁺ levels in wildtype mice. Moreover, Na-butyrate significantly inhibited Mg²⁺ uptake in Caco-2 cells, while Ca²⁺ uptake was unaffected. Although Na-butyrate significantly lowered total ATP production rate, and resulted in increased phosphorylation of AMP-activated protein kinase (AMPK), inhibition of Mg²⁺ uptake by butyrate preceded these consequences. Importantly, electrophysiological examinations demonstrated that intracellular butyrate directly reduced the activity of the heteromeric Mg²⁺ channel complex, transient receptor potential melastatin (TRPM)6/7. Blocking cellular butyrate uptake prevented its inhibitory effect on Mg²⁺ uptake, demonstrating that butyrate acts intracellularly. Our work identified butyrate as novel regulator of intestinal Mg²⁺ uptake that works independently from metabolic regulation. This finding further highlights the role of microbial fermentation in the regulation of mineral absorption.

Oral gamma-cyclodextrin-encapsulated tributyrin supplementation in young pigs with experimentally induced colitis

Disruption of intestinal integrity and barrier function due to tissue inflammation has negative implications on overall growth and well-being in young pigs. In this study, we investigated the effects of oral gamma-cyclodextrin-encapsulated tributyrin (TBCD) in young pigs experiencing dextran sodium sulfate (DSS)-induced colitis. Pigs (n = 32 boars) were weaned from the sow at postnatal day (PND) 2, allotted to treatment based on the litter of origin and body weight (BW), and reared artificially over a 26-d feeding period. Treatment groups included: 1) nutritionally adequate (control) milk replacer, no DSS (Control n = 8), 2) control milk replacer plus oral DSS (DSS, n = 7), and 3) control diet supplemented with 8.3 g of TBCD per kg of reconstituted milk replacer plus oral DSS (TBCD + DSS, n = 8). Colitis was induced by administering DSS at 1.25 g of DSS/kg BW daily in a reconstituted milk replacer from PND 14-18. Milk replacer and water were provided ad libitum throughout the 26-d study. All the data were analyzed using a one-way ANOVA using the MIXED procedure of SAS. Control and DSS pigs had similar BW throughout the study, while TBCD + DSS pigs exhibited decreased (P < 0.05) BW starting at approximately PND 15. Additionally, average daily gain (ADG) before and after initiation of DSS dosing, along with over the total study duration, was decreased (P < 0.05) in pigs receiving TBCD + DSS compared with the Control. Milk disappearance was decreased (P < 0.05) in TBCD + DSS pigs when compared with Control and DSS groups. Both the concentration and molar ratio of cecal butyrate concentrations were increased (P < 0.05) in TBCD + DSS pigs compared with the Control group. The DSS and TBCD + DSS treatments also increased (P < 0.05) butyrate concentrations in the luminal contents with the proximal colon compared with Control. TBCD + DSS and DSS pigs had increased (P < 0.05) mucosal width in the distal colon compared with Control, thereby indicating heightened intestinal inflammation. Overall, oral supplementation of encapsulated tributyrin increased the concentration of butyrate in the colon, but was unable to mitigate the negative effects of DSS-induced colitis.

Oleic Acid and Palmitic Acid from Bacteroides thetaiotaomicron and Lactobacillus johnsonii Exhibit Anti-Inflammatory and Antifungal Properties

A decrease in populations of Bacteroides thetaiotaomicron and Lactobacillus johnsonii is observed during the development of colitis and fungal overgrowth, while restoration of these populations reduces inflammatory parameters and fungal overgrowth in mice. This study investigated the effect of two fatty acids from B. thetaiotaomicron and L. johnsonii on macrophages and Caco-2 cells, as well as their impact on the inflammatory immune response and on Candida glabrata overgrowth in a murine model of dextran sulfate sodium (DSS)-induced colitis. Oleic acid (OA) and palmitic acid (PA) from L. johnsonii and B. thetaiotaomicron were detected during their interaction with epithelial cells from colon samples. OA alone or OA combined with PA (FAs) reduced the expression of proinflammatory mediators in intestinal epithelial Caco-2 cells challenged with DSS. OA alone or FAs increased FFAR1, FFAR2, AMPK, and IL-10 expression in macrophages. Additionally, OA alone or FAs decreased COX-2, TNFα, IL-6, and IL-12 expression in LPS-stimulated macrophages. In the DSS murine model, oral administration of FAs reduced inflammatory parameters, decreased Escherichia coli and Enterococcus faecalis populations, and eliminated C. glabrata from the gut. Overall, these findings provide evidence that OA combined with PA exhibits anti-inflammatory and antifungal properties.

Gut microbiota in systemic lupus erythematosus: A fuse and a solution

Gut commensals help shape and mold host immune system and deeply influence human health. The disease spectrum of mankind that gut microbiome may associate with is ever-growing, but the mechanisms are still enigmas. Characterized by loss of self-tolerance and sustained self-attack, systemic lupus erythematosus (SLE) is labeled with chronic inflammation, production of autoantibodies and multisystem injury, which so far are mostly incurable. Gut microbiota and their metabolites, now known as important environmental triggers of local/systemic immune responses, have been proposed to be involved in SLE development and progression probably through the following mechanisms: translocation beyond their niches; molecular mimicry to cross-activate immune response targeting self-antigens; epitope spreading to expand autoantibodies spectrum; and bystander activation to promote systemic inflammation. Gut microbiota which varies between individuals may also influence the metabolism and bio-transformation of disease-modifying anti-rheumatic drugs, thus associated with the efficacy and toxicity of these drugs, adding another explanation for heterogenic therapeutic responses. Modulation of gut microbiota via diet, probiotics/prebiotics, antibiotics/phages, fecal microbiota transplantation, or helminth to restore immune tolerance and homeostasis is expected to be a promising neoadjuvant therapy for SLE. We reviewed the advances in this territory and discussed the application prospect of modulating gut microbiota in controlling SLE.

The Effects of Sodium Butyrate, Coated Sodium Butyrate, and Butyric Acid Glycerides on Nutrient Digestibility, Gastrointestinal Function, and Fecal Microbiota in Turkeys

This study aimed to determine the efficacy of sodium butyrate (SB), coated sodium butyrate (CSB), and butyric acid glycerides (BAG) in turkey nutrition based on an analysis of nutrient digestibility, gastrointestinal function, and fecal bacterial populations. A total of 400 1-day-old female BIG 6 turkeys were divided into 4 groups, with 5 replicates per group and 20 birds per replicate, to determine the effects exerted by various forms of butyric acid (SB, CSB, and BAG). The addition of CSB and BAG to turkey diets improved the feed conversion ratio (FCR, p < 0.05), increased the values of the European Efficiency Index (EEI, p < 0.01) and duodenal villus height (p < 0.05), and decreased the fecal populations of Escherichia coli and Clostridium perfringens (p < 0.05). Dietary supplementation with BAG increased protein digestibility (p < 0.05). The analyzed forms of butyrate added to turkey diets increased the butyric acid concentration in the cecal digesta (p < 0.01). The results of this study indicate that protected forms of butyric acid can be valuable feed additives in turkey nutrition.

Saccharomyces cerevisiae I4 Showed Alleviating Effects on Dextran Sulfate Sodium-Induced Colitis of Balb/c Mice

Ulcerative colitis (UC) is a chronic inflammatory bowel disease. The purpose of this study was to investigate the ameliorating effects of three yeast strains, Saccharomyces cerevisiae I4, Clavispora lusitaniae 30 and Pichia kudriavzevii 11, isolated from traditional fermented dairy food in Xinjiang, China, on the ulcerative colitis symptoms of Balb/c mice treated by dextran sulfate sodium (DSS). Among which, S. cerevisiae I4 had good tolerance to simulated gastrointestinal juice and strong adhesion to HT–29 cells monolayers. Furthermore, the three yeast strains were oral administered to Balb/c mice with DSS induced colitis. The weight loss, colon shortening and histological injury of colitis mice were ameliorated. Then, oral administration of S. cerevisiae I4 improved the immune state by reducing the contents of TNF–α, IL–6 and IL–1β and increasing immunoglobulin. The relative expression of intestinal barrier proteins Claudin–1, Occludin and Zonula Occludins–1 (ZO–1) of the mice enhanced, and the short chain fatty acids (SCFAs) content such as Propionic acid, Butyric acid, Isobutyric acid and Isovaleric acid in the feces of the mice increased to varying degrees, after S. cerevisiae I4 treatment compared with the model group of drinking 3% DSS water without yeast treatment. Moreover, S. cerevisiae I4 treatment lifted the proportion of beneficial bacteria such as Muribaculaceae, Lactobacillaceae and Rikenellaceae in the intestinal tract of the mice, the abundance of harmful bacteria such as Staphylococcus aureus and Turicibacter was decreased. These results suggested that S. cerevisiae I4 could alleviate DSS induced colitis in mice by enhancing intestinal barrier function and regulating intestinal flora balance.

Impact of experimental colitis on mitochondrial bioenergetics in intestinal epithelial cells

Intestinal homeostasis is highly dependent on optimal epithelial barrier function and permeability. Intestinal epithelial cells (IEC) regulate these properties acting as cellular gatekeepers by selectively absorbing nutrients and controlling the passage of luminal bacteria. These functions are energy demanding processes that are presumably met through mitochondrial-based processes. Routine methods for examining IEC mitochondrial function remain sparse, hence, our objective is to present standardized methods for quantifying mitochondrial energetics in an immortalized IEC line. Employing the murine IEC^4.1 cell line, we present adapted methods and protocols to examine mitochondrial function using two well-known platforms: the Seahorse Extracellular Flux Analyzer and Oxygraph-2 k. To demonstrate the applicability of these protocols and instruments, IEC were treated with and without the murine colitogenic agent, dextran sulfate sodium (DSS, 2% w/v). Profound impairments with DSS treatment were found with both platforms, however, the Oxygraph-2 k allowed greater resolution of affected pathways including short-chain fatty acid metabolism. Mitochondrial functional analysis is a novel tool to explore the relationship between IEC energetics and functional consequences within the contexts of health and disease. The outlined methods offer an introductory starting point for such assessment and provide the investigator with insights into platform-specific capabilities.

Hallmarks of the human intestinal microbiome on liver maturation and function

As one of the most metabolically complex systems in the body, the liver ensures multi-organ homeostasis and ultimately sustains life. Nevertheless, during early postnatal development, the liver is highly immature and takes about 2 years to acquire and develop almost all of its functions. Different events occurring at the environmental and cellular levels are thought to mediate hepatic maturation and function postnatally. The crosstalk between the liver, the gut and its microbiome has been well appreciated in the context of liver disease, but recent evidence suggests that the latter could also be critical for hepatic function under physiological conditions. The gut-liver crosstalk is thought to be mediated by a rich repertoire of microbial metabolites that can participate in a myriad of biological processes in hepatic sinusoids, from energy metabolism to tissue regeneration. Studies on germ-free animals have revealed the gut microbiome as a critical contributor in early hepatic programming, and this influence extends throughout life, mediating liver function and body homeostasis. In this seminar, we describe the microbial molecules that have a known effect on the liver and discuss how the gut microbiome and the liver evolve throughout life. We also provide insights on current and future strategies to target the gut microbiome in the context of hepatology research.

Dual role of microbiota-derived short-chain fatty acids on host and pathogen

A growing body of documents shows microbiota produce metabolites such as short-chain fatty acids (SCFAs) as crucial executors of diet-based microbial influence the host and bacterial pathogens. The production of SCFAs depends on the metabolic activity of intestinal microflora and is also affected by dietary changes. SCFAs play important roles in maintaining colonic health as an energy source, as a regulator of gene expression and cell differentiation, and as an anti-inflammatory agent. Additionally, the regulated expression of virulence genes is critical for successful infection by an intestinal pathogen. Bacteria rely on sensing environmental signals to find preferable niches and reach the infectious state. This review will present data supporting the diverse functional roles of microbiota-derived butyrate, propionate, and acetate on host cellular activities such as immune modulation, energy metabolism, nervous system, inflammation, cellular differentiation, and anti-tumor effects, among others. On the other hand, we will discuss and summarize data about the role of these SCFAs on the virulence factor of bacterial pathogens. In this regard, receptors and signaling routes for SCFAs metabolites in host and pathogens will be introduced.

In Vivo Healthy Benefits of Galacto-Oligosaccharides from Lupinus albus (LA-GOS) in Butyrate Production through Intestinal Microbiota

Animal digestive systems host microorganism ecosystems, including integrated bacteria, viruses, fungi, and others, that produce a variety of compounds from different substrates with healthy properties. Among these substrates, α-galacto-oligosaccharides (GOS) are considered prebiotics that promote the grow of gut microbiota with a metabolic output of Short Chain Fatty Acids (SCFAs). In this regard, we evaluated Lupinus albus GOS (LA-GOS) as a natural prebiotic using different animal models. Therefore, the aim of this work was to evaluate the effect of LA-GOS on the gut microbiota, SCFA production, and intestinal health in healthy and induced dysbiosis conditions (an ulcerative colitis (UC) model). Twenty C57BL/6 mice were randomly allocated in four groups (n = 5/group): untreated and treated non-induced animals, and two groups induced with 2% dextran sulfate sodium to UC with and without LA-GOS administration (2.5 g/kg bw). We found that the UC treated group showed a higher goblet cell number, lower disease activity index, and reduced histopathological damage in comparison to the UC untreated group. In addition, the abundance of positive bacteria to butyryl-CoA transferase in gut microbiota was significantly increased by LA-GOS treatment, in healthy conditions. We measured the SCFA production with significant differences in the butyrate concentration between treated and untreated healthy groups. Finally, the pH level in cecum feces was reduced after LA-GOS treatment. Overall, we point out the in vivo health benefits of LA-GOS administration on the preservation of the intestinal ecosystem and the promotion of SCFA production.

Butyrate Alters Pyruvate Flux and Induces Lipid Accumulation in Cultured Colonocytes

Butyrate is considered the primary energy source of colonocytes and has received wide attention due to its unique health benefits. Insight into the mechanistic effects of butyrate on cellular and metabolic function relies mainly on research in in-vitro-cultured cells. However, cells in culture differ from those in vivo in terms of metabolic phenotype and nutrient availability. For translation, it is therefore important to understand the impact of different nutrients on the effects of butyrate. We investigated the metabolic consequences of butyrate exposure under various culturing conditions, with a focus on the interaction between butyrate and glucose. To investigate whether the effects of butyrate were different between cells with high and low mitochondrial capacity, we cultured HT29 cells under either low- (0.5 mM) or high- (25 mM) glucose conditions. Low-glucose culturing increased the mitochondrial capacity of HT29 cells compared to high-glucose (25 mM) cultured HT29 cells. Long-term exposure to butyrate did not alter mitochondrial bioenergetics, but it decreased glycolytic function, regardless of glucose availability. In addition, both high- and low-glucose-grown HT29 cells showed increased lipid droplet accumulation following long-term butyrate exposure. Acute exposure of cultured cells (HT29 and Caco-2) to butyrate increased their oxygen consumption rate (OCR). A simultaneous decrease in extracellular acidification rate (ECAR) was observed. Furthermore, in the absence of glucose, OCR did not increase in response to butyrate. These results lead us to believe that butyrate itself was not responsible for the observed increase in OCR, but, instead, butyrate stimulated pyruvate flux into mitochondria. Indeed, blocking of the mitochondrial pyruvate carrier prevented a butyrate-induced increase in oxygen consumption. Taken together, our results indicate that butyrate itself is not oxidized in cultured cells but instead alters pyruvate flux and induces lipid accumulation.

Interaction Between the Microbiota, Epithelia, and Immune Cells in the Intestine

The gastrointestinal tract harbors numerous commensal bacteria, referred to as the microbiota, that benefit host health by digesting dietary components and eliminating pathogens. The intestinal microbiota maintains epithelial barrier integrity and shapes the mucosal immune system, balancing host defense and oral tolerance with microbial metabolites, components, and attachment to host cells. To avoid aberrant immune responses, epithelial cells segregate the intestinal microbiota from immune cells by constructing chemical and physical barriers, leading to the establishment of host-commensal mutualism. Furthermore, intestinal immune cells participate in the maintenance of a healthy microbiota community and reinforce epithelial barrier functions. Perturbations of the microbiota composition are commonly observed in patients with autoimmune diseases and chronic inflammatory disorders. An understanding of the intimate interactions between the intestinal microbiota, epithelial cells, and immune cells that are crucial for the maintenance of intestinal homeostasis might promote advances in diagnostic and therapeutic approaches for various diseases.

Preventing Colorectal Cancer through Prebiotics

Colorectal cancer (CRC), the third most common cancer in the world, has been recently rising in emerging countries due to environmental and lifestyle factors. Many of these factors are brought up by industrialization, which includes lack of physical activity, poor diet, circadian rhythm disruption, and increase in alcohol consumption. They can increase the risk of CRC by changing the colonic environment and by altering gut microbiota composition, a state referred to as gut dysbiosis. Prebiotics, which are nutrients that can help maintain intestinal microbial homeostasis and mitigate dysbiosis, could be beneficial in preventing inflammation and CRC. These nutrients can hinder the effects of dysbiosis by encouraging the growth of beneficial bacteria involved in short-chain fatty acids (SCFA) production, anti-inflammatory immunity, maintenance of the intestinal epithelial barrier, pro-apoptotic mechanisms, and other cellular mechanisms. This review aims to summarize recent reports about the implication of prebiotics, and probable mechanisms, in the prevention and treatment of CRC. Various experimental studies, specifically in gut microbiome, have effectively demonstrated the protective effect of prebiotics in the progress of CRC. Hence, comprehensive knowledge is urgent to understand the clinical applications of prebiotics in the prevention or treatment of CRC.

Temporal dynamics of gut microbiota in caged laying hens: a field observation from hatching to end of lay

Gut health has major implications for the general health of food-producing animals such as the layer birds used in the egg industry. In order to modulate gut microbiota for the benefit of gut health, an understanding of the dynamics and details of the development of gut microbiota is critical. The present study investigated the phylogenetic composition of the gut microbiota of a commercial layer flock raised in cages from hatch to the end of the production cycle. This study also aimed to understand the establishment and development of gut microbiota in layer chickens. Results showed that the faecal microbiota was dominated by phyla Firmicutes and Proteobacteria in the rearing phase, but Bacteroidetes in mid lay and late lay phase. The gut microbiota composition changed significantly during the transfer of the flock from the rearing to the production shed. The richness and diversity of gut microbiota increased after week 6 of the flocks age and stabilized in the mid and late lay phase. The overall dynamics of gut microbiota development was similar to that reported in earlier studies, but the phylogenetic composition at the phylum and family level was different. The production stage of the birds is one of the important factors in the development of gut microbiota. This study has contributed to a better understanding of baseline gut microbiota development over the complete life cycles in layer chickens and will help to develop strategies to improve the gut health. KEY POINTS: • Faecal microbiota of caged hens was dominated by phyla Firmicutes and Proteobacteria in the rearing phase. • The gut microbiota composition changed significantly during the transfer of the flock from the rearing to the production shed. • The richness and diversity of gut microbiota increased after week 6 of the flocks age and stabilized in the mid and late lay phase.

Role of microbiota-derived short-chain fatty acids in cancer development and prevention

Following cancer, cells in a particular tissue can no longer respond to the factors involved in controlling cell survival, differentiation, proliferation, and death. In recent years, it has been indicated that alterations in the gut microbiota components, intestinal epithelium, and host immune system are associated with cancer incidence. Also, it has been demonstrated that the short-chain fatty acids (SCFAs) generated by gut microbiota are vitally crucial in cell homeostasis as they contribute to the modulation of histone deacetylases (HDACs), resulting effected cell attachment, immune cell immigration, cytokine production, chemotaxis, and the programmed cell death. Therefore, the manipulation of SCFA levels in the intestinal tract by alterations in the microbiota structure can be potentially taken into consideration for cancer treatment/prevention. In the current study, we will explain the most recent findings on the detrimental or protective roles of SFCA (particularly butyrate, propionate, and acetate) in several cancers, including bladder, colon, breast, stomach, liver, lung, pancreas, and prostate cancers.

The Role of Enterobacteriaceae in Gut Microbiota Dysbiosis in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) are a group of chronic gastrointestinal inflammatory diseases with unknown etiology. There is a combination of well documented factors in their pathogenesis, including intestinal microbiota dysbiosis. The symbiotic microbiota plays important functions in the host, and the loss of beneficial microbes could favor the expansion of microbial pathobionts. In particular, the bloom of potentially harmful Proteobacteria, especially Enterobacteriaceae, has been described as enhancing the inflammatory response, as observed in IBDs. Herein, we seek to investigate the contribution of Enterobacteriaceae to IBD pathogenesis whilst considering the continuous expansion of the literature and data. Despite the mechanism of their expansion still remaining unclear, their expansion could be correlated with the increase in nitrate and oxygen levels in the inflamed gut and with the bile acid dysmetabolism described in IBD patients. Furthermore, in several Enterobacteriaceae studies conducted at a species level, it has been suggested that some adherent-invasive Escherichia coli (AIEC) play an important role in IBD pathogenesis. Overall, this review highlights the pivotal role played by Enterobacteriaceae in gut dysbiosis associated with IBD pathogenesis and progression.

Postbiotics, Metabolic Signaling, and Cancer

Postbiotics are health-promoting microbial metabolites delivered as a functional food or a food supplement. They either directly influence signaling pathways of the body or indirectly manipulate metabolism and the composition of intestinal microflora. Cancer is the second leading cause of death worldwide and even though the prognosis of patients is improving, it is still poor in the substantial part of the cases. The preventable nature of cancer and the importance of a complex multi-level approach in anticancer therapy motivate the search for novel avenues of establishing the anticancer environment in the human body. This review summarizes the principal findings demonstrating the usefulness of both natural and synthetic sources of postbotics in the prevention and therapy of cancer. Specifically, the effects of crude cell-free supernatants, the short-chain fatty acid butyrate, lactic acid, hydrogen sulfide, and β-glucans are described. Contradictory roles of postbiotics in healthy and tumor tissues are highlighted. In conclusion, the application of postbiotics is an efficient complementary strategy to combat cancer.

The Protective Role of Butyrate against Obesity and Obesity-Related Diseases

Worldwide obesity is a public health concern that has reached pandemic levels. Obesity is the major predisposing factor to comorbidities, including type 2 diabetes, cardiovascular diseases, dyslipidemia, and non-alcoholic fatty liver disease. The common forms of obesity are multifactorial and derive from a complex interplay of environmental changes and the individual genetic predisposition. Increasing evidence suggest a pivotal role played by alterations of gut microbiota (GM) that could represent the causative link between environmental factors and onset of obesity. The beneficial effects of GM are mainly mediated by the secretion of various metabolites. Short-chain fatty acids (SCFAs) acetate, propionate and butyrate are small organic metabolites produced by fermentation of dietary fibers and resistant starch with vast beneficial effects in energy metabolism, intestinal homeostasis and immune responses regulation. An aberrant production of SCFAs has emerged in obesity and metabolic diseases. Among SCFAs, butyrate emerged because it might have a potential in alleviating obesity and related comorbidities. Here we reviewed the preclinical and clinical data that contribute to explain the role of butyrate in this context, highlighting its crucial contribute in the diet-GM-host health axis.

Inflammatory Bowel Diseases (IBD) and the Microbiome-Searching the Crime Scene for Clues

Inflammatory bowel diseases (IBD) develop via convergence of environmental, microbial, immunological, and genetic factors. Alterations in the gut microbiota have been associated with development and progression of IBD, but it is not clear which populations of microbes are involved or how they might contribute to IBD. We review the genetic and environmental factors affecting the gut microbiota, the roles of gut microbes and their bioproducts in the development and clinical course of IBD, and strategies by which microbiome-based therapies can be used to prevent, manage, and eventually cure IBD. We discuss research findings that help bridge the gap between the basic sciences and clinical application.

Paneth cell-derived growth factors support tumorigenesis in the small intestine

Paneth cells, known for their production of antimicrobial peptides and growth factors in the gut epithelium, are found to play a key role in intestinal tumor formation through secretion of Wnt3.

Paneth cells (PCs) are small intestinal epithelial cells that secrete antimicrobial peptides and growth factors, such as Wnt ligands. Intriguingly, the context in which PC-derived Wnt secretion is relevant in vivo remains unknown as intestinal epithelial ablation of Wnt does not affect homeostatic proliferation or restitution after irradiation injury. Considering the importance of growth factors in tumor development, we explored here the role of PCs in intestinal carcinogenesis using a genetic model of PC depletion through conditional expression of diphtheria toxin-α subunit. PC depletion in Apc^Min mice impaired adenoma development in the small intestine and led to decreased Wnt3 expression in small bowel adenomas. To determine if PC-derived Wnt3 was required for adenoma development, we examined tumor formation after PC-specific ablation of Wnt3. We found that this was sufficient to decrease small intestinal adenoma formation; moreover, organoids derived from these tumors displayed slower growth capacity. Overall, we report that PC-derived Wnt3 is required to sustain early tumorigenesis in the small bowel and identify a clear role for PC-derived Wnt production in intestinal pathology.

Role of gut microbiota-derived metabolites on vascular calcification in CKD

The interaction between gut microbiota and the host has gained widespread concern. Gut microbiota not only provides nutrients from the ingested food but also generates bioactive metabolites and signalling molecules to impact host physiology, especially in chronic kidney disease (CKD). The development of CKD, accompanied by changed diet and medication, alters the gut flora and causes the effect in distant organs, leading to clinical complications. Vascular calcification (VC) is an actively regulated process and a high prevalence of VC in CKD has also been linked to an imbalance in gut microbiota and altered metabolites. In this review, we focused on gut microbiota-derived metabolites involved in VC in CKD and explained how these metabolites influence the calcification process. Correcting the imbalance of gut microbiota and regulating microbiota-derived metabolites by dietary modification and probiotics are new targets for the improvement of the gut-kidney axis, which indicate innovative treatment options of VC in CKD.

Effects of lipopolysaccharide exposure on the inflammatory response, butyrate flux, and metabolic function of the ruminal epithelium using an ex vivo model

Acidotic conditions in the rumen have been associated with compromised barrier function of the ruminal epithelium and translocation of microbe-associated molecular patterns (MAMP) such as lipopolysaccharide (LPS). Interaction of MAMP with the ruminal epithelium may also induce a local proinflammatory response. The aim of this study was to evaluate the potential proinflammatory response of the ruminal epithelium following LPS exposure in Ussing chambers, to investigate whether LPS exposure affects the flux and metabolism of butyrate. Ruminal epithelial tissue from 9 Holstein bull calves were mounted into Ussing chambers and exposed to 0, 10,000, 50,000, or 200,000 endotoxin units (EU)/mL LPS for a duration of 5 h. Radiolabeled ¹⁴C-butyrate (15 mM) was added to the mucosal buffer to assess the mucosal-to-serosal flux of ¹⁴C-butyrate. Additional Ussing chambers, without radioisotope, were exposed to either 0 or 200,000 EU/mL LPS and were used to measure the release of β-hydroxybutyrate (BHB) and IL1B into the buffer, and to collect epithelial tissue for analysis of gene expression. Genes associated with inflammation (TNF, IL1B, CXCL8, PTGS2, TGFB1, TLR2, TLR4), nutrient transport (MCT1, MCT4, SLC5A8, GLUT1), and metabolic function (ACAT1, BDH1, MCU, IGFBP3, IGFBP5) were selected and analyzed using quantitative real-time PCR. Butyrate flux was not significantly affected by LPS exposure; however, we detected a tendency for the mucosal-to-serosal butyrate flux to increase linearly with LPS dose. Bidirectional releases of BHB and IL1B were not affected by LPS exposure. Expression of PTGS2, TGFB1, TLR4, and MCU were downregulated following exposure to LPS ex vivo. We detected no effects on the expression of genes associated with nutrient transport. The results of the present study are interpreted to indicate that, although the inflammatory response of the ruminal epithelium was slightly suppressed, exposure to LPS may have altered metabolic function.

Effects of a proinflammatory response on metabolic function of cultured, primary ruminal epithelial cells

Inflammation of ruminal epithelium may occur during ruminal acidosis as a result of translocation and interaction of ruminal epithelial cells (REC) with molecules such as lipopolysaccharide (LPS). Such inflammation has been reported to alter cellular processes such as nutrient absorption, metabolic regulation, and energy substrate utilization in other cell types but has not been investigated for REC. The objectives of this study were to investigate the effects of LPS on metabolism of short-chain fatty acids by primary REC, as well as investigating the effects of media containing short-chain fatty acids on the proinflammatory response. Ruminal papillae from 9 yearling Speckle Park beef heifers were used to isolate and culture primary REC. Cells were grown in minimum essential medium (MEM) for 12 d before use and then reseeded in 24-well culture plates. The study was conducted as a 2 × 2 factorial, where cells were grown in unaltered MEM (REG) or medium containing 2 mM butyrate and 5 mM propionate (SCFA) with (50,000 EU/mL; +LPS) or without LPS (-LPS) for 24 h. Supernatant samples were collected for analysis of glucose and SCFA consumption. Cells were collected to determine the expression of mRNA for genes associated with inflammation (TNF, IL1B, CXCL2, CXCL8, PTGS2, and TLR4), purinergic signaling (P2RX7, ADORAB2, and CD73), nutrient transport [SLC16A1 (MCT1), SLC16A3 (MCT4), SLC5A8, and MCU], and cell metabolism [ACAT1, SLC2A1 (GLUT1), IGFBP3, and IGFBP5]. Protein expression of TLR4 and ketogenic enzymes (BDH1 and HMGCS1) were also analyzed using flow cytometry. Statistical analysis was conducted with the MIXED model of SAS version 9.4 (SAS Institute Inc., Cary, NC) with medium, LPS exposure, and medium × LPS interaction as fixed effects and animal within plate as a random effect. Cells tended to consume more glucose when exposed to LPS as opposed to no LPS exposure (31.8 vs. 28.7 ± 2.7), but consumption of propionate and butyrate was not influenced by LPS. Expression of TNF and IL1B was upregulated when exposed to LPS, and expression of CXCL2 and CXCL8 increased following LPS exposure with SCFA (medium × LPS). For cells exposed to LPS, we found a downregulation of ACAT1 and IGFBP5 and an upregulation of SLC2A1, SLC16A3, MCU, and IGFBP3. Medium with SCFA led to greater expression of MCU. SLC16A1 was upregulated in cells incubated with SCFA and without LPS compared with the other groups. Protein expression of ketogenic enzymes was not affected; however, BDH1 mean fluorescence intensity (MFI) expression tended to be less in cells exposed to LPS. These data are interpreted to indicate that when REC are exposed to LPS, they may increase glucose metabolism. Moreover, transport of solutes was affected by SCFA in the medium and by exposure to LPS. Overall, the results suggest that metabolic function of REC in vitro is altered by a proinflammatory response, which may lead to a greater glucose requirement.

The Role of Diet Related Short-Chain Fatty Acids in Colorectal Cancer Metabolism and Survival: Prevention and Therapeutic Implications

Colorectal Cancer (CRC) is a major cause of cancer-related death worldwide. CRC increased risk has been associated with alterations in the intestinal microbiota, with decreased production of Short Chain Fatty Acids (SCFAs). SCFAs produced in the human colon are the major products of bacterial fermentation of undigested dietary fiber and starch. While colonocytes use the three major SCFAs, namely acetate, propionate and butyrate, as energy sources, transformed CRC cells primarily undergo aerobic glycolysis. Compared to normal colonocytes, CRC cells exhibit increased sensitivity to SCFAs, thus indicating they play an important role in cell homeostasis. Manipulation of SCFA levels in the intestine, through changes in microbiota, has therefore emerged as a potential preventive/therapeutic strategy for CRC. Interest in understanding SCFAs mechanism of action in CRC cells has increased in the last years. Several SCFA transporters like SMCT-1, MCT-1 and aquaporins have been identified as the main transmembrane transporters in intestinal cells. Recently, it was shown that acetate promotes plasma membrane re-localization of MCT-1 and triggers changes in the glucose metabolism. SCFAs induce apoptotic cell death in CRC cells, and further mechanisms have been discovered, including the involvement of lysosomal membrane permeabilization, associated with mitochondria dysfunction and degradation. In this review, we will discuss the current knowledge on the transport of SCFAs by CRC cells and their effects on CRC metabolism and survival. The impact of increasing SCFA production by manipulation of colon microbiota on the prevention/therapy of CRC will also be addressed.

UCC118 supplementation reduces exercise-induced gastrointestinal permeability and remodels the gut microbiome in healthy humans

Dysregulation of gut microbiota and intestinal barrier function has emerged as potential mechanisms underlying digestive diseases, yet targeted therapies are lacking The purpose of this investigation was to assess the efficacy of UCC118, a characterized probiotic strain, on exercise‐induced GI permeability in healthy humans. In a randomized, double‐blind, placebo‐controlled crossover study, seven healthy adults received 4 weeks of daily UCC118 or placebo supplementation. GI hyperpermeability was induced by strenuous treadmill running performed before and after each supplementation period. While running, participants ingested 5 g of lactulose, rhamnose, and sucrose. Urine was collected before, immediately after, and every hour for 5 h after exercise to assess GI permeability. Metagenomic sequencing was performed on fecal homogenates collected prior to exercise to identify changes in microbial diversity and taxon abundances. Inflammatory biomarkers were assessed from blood and fecal homogenates collected prior to and immediately following the cessation of exercise. Exercise significantly induced intestinal permeability of lactulose, rhamnose, and sucrose (P < 0.001). UCC118 significantly reduced sucrose (Δ = −0.38 ± 0.13 vs. 1.69 ± 0.79; P < 0.05) recovery, with no substantial change in lactulose (Δ = −0.07 ± 0.23 vs. 0.35 ± 0.15; P = 0.16) or rhamnose (Δ = −0.06 ± 0.22 vs. 0.48 ± 0.28; P = 0.22). Taxonomic sequencing revealed 99 differentially regulated bacteria spanning 6 taxonomic ranks (P < 0.05) after UCC118 supplementation. No differences in plasma IL‐6 or fecal zonulin were observed after UCC118 supplementation. The results described herein provide proof of principle that 4 weeks of UCC118 supplementation attenuated exercise‐induced intestinal hyperpermeability. Further research is warranted to investigate the as‐yet‐to‐be defined molecular processes of intestinal hyperpermeability and the effects of probiotic supplementation.

Dysregulation of gut microbiota and intestinal barrier function have emerged as potential mechanisms underlying digestive diseases, yet targeted therapies are lacking. In a randomized, double‐blind, placebo‐controlled crossover study, 7 healthy adults 30 received 4 weeks of daily UCC118 or placebo supplementation. UCC118 significantly reduced sucrose recovery. Taxonomic sequencing revealed 99 differentially regulated gut microbes by UCC118. The results herein provide proof of principle that UCC118 supplementation can reduce intestinal hyperpermeability.

Nutritional Management of Paediatric Crohn’s Disease

For many people with Crohn’s disease (CD), onset occurs in childhood or adolescence. Treatment for CD has moved from predominantly surgical to, more often, pharmacological. While successful for many, others have tried various medications and combinations without long-term success and, for all, drug treatment needs to be balanced with potential therapy risks. Findings that diet can impact pathogenesis of CD to cause and exacerbate symptoms have inspired studies of dietary interventions. The Crohn’s Disease Exclusion Diet (CDED) was developed following the observation that certain dietary components were linked to inflammation and gut dysbiosis found in those with CD. This three-phase diet included two periods of a highly-controlled and prescribed diet, followed by a maintenance diet in which patients had a wider choice of foods. The diet limited ingestion of foods that may trigger inflammation and/or dysbiosis in CD, such as saturated fats, wheat, carrageenan, and some dairy products, and included healthy choices, such as fruits, vegetables, lean protein sources, and complex carbohydrates. It was nutritionally balanced, science-based, and included foods that were widely accessible. Based on findings from clinical trials and case studies, four experts (Prof Lionetti, Prof Martín-de-Carpi, Mrs Sigall-Boneh, and Prof Wine) discussed the background of CD, current treatment options, the utility of dietary therapies including CDED, and how all healthcare professionals (HCP) looking after children and adolescents with CD should consider the use of diet as part of their therapy.

Opioids Impair Intestinal Epithelial Repair in HIV-Infected Humanized Mice

Intestinal barrier dysfunction and subsequent microbial translocation play crucial roles in persistent immune activation leading to HIV disease progression. Opioid use is associated with worse outcome in HIV-infected patients. The exacerbated disease progression by opioids is mainly driven by excessive intestinal inflammation and increased gut permeability. The objective of this study is to investigate how opioids potentiate HIV disease progression by compromising intestinal barrier function and impairing intestinal epithelial self-repair mechanism. In the present study, abnormal intestinal morphology and reduced epithelial proliferation were observed in bone marrow-liver-thymus humanized mice and in HIV-infected patients who were exposed to opioids. In bone marrow-liver-thymus mice, HIV, and morphine independently, and additively induced gut dysbiosis, especially depletion of Lachnospiraceae, Ruminococcaceae, and Muribaculaceae. We also observed that the abundance of Lachnospiraceae, Ruminococcaceae, and Muribaculaceae negatively correlated with apoptosis of epithelial cells, and intestinal IL-6 levels. Previous studies have shown that these bacterial families play crucial roles in maintaining intestinal homeostasis because they include most short-chain fatty acid-producing members. Short-chain fatty acids have been shown to maintain stem cell populations and suppress inflammation in the gut by inhibiting histone deacetylases (HDAC). In addition, we demonstrate that morphine exposure inhibited growth of intestinal organoids derived from HIV transgenic mice by suppressing Notch signaling in an HDAC-dependent manner. These studies implicate an important role for HDAC in intestinal homeostasis and supports HDAC modulation as a therapeutic intervention in improving care of HIV patients, especially in opioid-abusing population.

Early life nutrition influences susceptibility to chronic inflammatory colitis in later life

The first thousand days of life are a critical time of development in humans during which the risk profile for diseases in later life can be modified. Nevertheless, long-term consequences of early environment on susceptibility to intestinal diseases have not yet been assessed. Using a mouse model of postnatal growth restriction (PNGR), we showed that early life nutrition influences intestinal maturation and gut health in later life. PNGR induced an alteration of the intestinal barrier in pups at weaning, resulting in increased intestinal permeability, and affected gut bacterial colonization. Specifically, pups with PNGR harbored a decreased bacterial diversity, higher Enterococcus spp., Staphylococcus spp., and Escherichia-Shigella spp., and lower Odoribacter spp. and several members of the Lachnospiraceae family. The lack of an efficient intestinal barrier in early life and the dysbiosis induced by PNGR were associated with a higher susceptibility to chronic colitis in adulthood.

Systematic Review and Meta-analysis: Short-Chain Fatty Acid Characterization in Patients With Inflammatory Bowel Disease

BACKGROUND

Alterations in gut microbiota and short-chain fatty acids (SCFAs) have been reported in inflammatory bowel disease (IBD), but the results are conflicting. The aim of this study was to perform a meta-analysis to explore the characterization of SCFAs in IBD patients and their potential role in the occurrence and development of IBD.

METHODS

Case-control studies investigating SCFAs in IBD patients were identified from several English databases. The standardized mean difference (SMD) with 95% confidence interval (CI) was calculated using the random-effects model.

RESULTS

The SMDs of acetate, valerate, and total SCFAs in ulcerative colitis (UC) patients were -0.51 (95% CI, -0.90 to -0.13), -0.65 (95% CI, -1.02 to -0.28), and -0.51 (95% CI, -0.95 to -0.07), respectively. The SMDs of acetate, propionate, and butyrate in patients with active UC were -1.74 (95% CI, -3.15 to -0.33), -2.42 (95% CI, -4.24 to -0.60), and -1.99 (95% CI, -3.39 to -0.60), respectively. However, the SMD of butyrate in UC patients in remission was 0.72 (95% CI, 0.34 to 1.11). In addition, the SMDs of acetate, butyrate, and valerate in Crohn's disease (CD) patients were -1.43 (95% CI, -2.81 to -0.04), -0.77 (95% CI, -1.39 to -0.14), and -0.75 (95% CI, -1.47 to -0.02), respectively. Finally, the SMDs of acetate, propionate, butyrate, valerate, and lactate in IBD patients were -2.19 (95% CI, -3.98 to -0.39), -1.64 (95% CI, -3.02 to -0.25), -1.98 (95% CI, -3.93 to -0.03), -0.55 (95% CI, -0.93 to -0.18), and 4.02 (95% CI, 1.44 to 6.61), respectively.

CONCLUSIONS

There were alterations of SCFAs in IBD patients, and inconsistent SCFA alterations were found in CD and UC. More importantly, inverse SCFA alterations existed in patients with active UC and those in remission.