Indigestible Polysaccharides Research Articles

Structural characterization and Bacteroides proliferation promotion activity of a novel homogeneous arabinoglucuronoxylan from Commelina communis L.

Commelina communis L., a functional food and herbal plant in Asia, has been used against obesity, diabetes, and infections for centuries. A growing body of studies has demonstrated that indigestible polysaccharides are significant in obesity management. However, the structures and bioactivities of homogeneous polysaccharides from C. communis remain unclear. This study presented the structural characterization, simulated digestion, and human gut Bacteroides proliferation promotion activity of a novel homogeneous polysaccharide (CCB-3) from C. communis. The results showed that CCB-3 was an arabinoglucuronoxylan, primarily composed of arabinose, galactose, xylose, glucuronic acid (GlcA), and 4-O-methyl GlcA with a molecular weight (Mw) of 58.8 kDa. Following a 6-hour exposure to simulated gastrointestinal fluid, the Mw of CCB-3 remained unchanged, revealing that CCB-3 was an indigestible polysaccharide. Notably, CCB-3 could promote the proliferation of B. thetaiotaomicron, B. ovatus, and B. cellulosilyticus and produce short-chain fatty acids (SCFAs) and 1,2-propanediol. These findings might shed light on the discovery of polysaccharide-based leading compounds from C. communis against obesity.

The Role of Short Chain Fatty Acids in Inflammation and Body Health.

Short chain fatty acids (SCFAs), mainly including acetate, propionate and butyrate, are produced by intestinal bacteria during the fermentation of partially digested and indigestible polysaccharides. SCFAs play an important role in regulating intestinal energy metabolism and maintaining the homeostasis of the intestinal environment and also play an important regulatory role in organs and tissues outside the gut. In recent years, many studies have shown that SCFAs can regulate inflammation and affect host health, and two main signaling mechanisms have also been identified: the activation of G-protein coupled receptors (GPCRs) and inhibition of histone deacetylase (HDAC). In addition, a growing body of evidence highlights the importance of every SCFA in influencing health maintenance and disease development. In this review, we summarized the recent advances concerning the biological properties of SCFAs and their signaling pathways in inflammation and body health. Hopefully, it can provide a systematic theoretical basis for the nutritional prevention and treatment of human diseases.

Integrated transcriptomics and proteomics analysis reveals muscle metabolism effects of dietary Ulva lactuca and ulvan lyase supplementation in weaned piglets

Seaweeds, including the green Ulva lactuca, can potentially reduce competition between feed, food, and fuel. They can also contribute to the improved development of weaned piglets. However, their indigestible polysaccharides of the cell wall pose a challenge. This can be addressed through carbohydrase supplementation, such as the recombinant ulvan lyase. The objective of our study was to assess the muscle metabolism of weaned piglets fed with 7% U. lactuca and 0.01% ulvan lyase supplementation, using an integrated transcriptomics (RNA-seq) and proteomics (LC–MS) approach. Feeding piglets with seaweed and enzyme supplementation resulted in reduced macronutrient availability, leading to protein degradation through the proteasome (PSMD2), with resulting amino acids being utilized as an energy source (GOT2, IDH3B). Moreover, mineral element accumulation may have contributed to increased oxidative stress, evident from elevated levels of antioxidant proteins like catalase, as a response to maintaining tissue homeostasis. The upregulation of the gene AQP7, associated with the osmotic stress response, further supports these findings. Consequently, an increase in chaperone activity, including HSP90, was required to repair damaged proteins. Our results suggest that enzymatic supplementation may exacerbate the effects observed from feeding U. lactuca alone, potentially due to side effects of cell wall degradation during digestion.

Diversity of the infusoria symbiofauna of cattle

Infusoria from the digestive tract of herbivorous mammals have been known to science for almost a century and a half. However, protozoans remain an understudied group of rumen dwellers in ruminants. In cattle, in a multi-chambered stomach, in addition to microorganisms (fungi and bacteria), there are a large number of protozoa (infusoria), which also participate in the digestive processes that support the vital activity of the body. Endobiontic infusoria take an active part in the digestion of complex carbohydrates, fiber, in the breakdown of indigestible polysaccharides, which are essential sources of energy for animals. In this regard, the study of the species and quantitative composition of the infusoria fauna of cattle bred in the Far North, as one of the factors of sustainable adaptation to extreme conditions, is of great scientific and practical interest.This article presents the results of a study of endobiontic infusoria of cattle breeds bred in Yakutia. A total of 36 species have been identified and described in 12 genera and 3 families. It was found that the genus Entodinium and the genus Isotricha were the most represented in the Yakut cattle, while the genus Entodinium and Euplodiniumin are in the crossbred and cultivated cattle. The smallest genus in all groups are Polyplastron and Metadinium.

Effect of in vitro simulated digestion and fecal fermentation on Boletus auripes polysaccharide characteristics and intestinal flora

Boletus auripes is edible and medicinal boletus mushrooms rich in diverse nutrients and bioactive compounds, of which indigestible dietary polysaccharides are the most abundant compounds involved the regulation of gut microbes. However, the physicochemical, digestive, and fermentation characteristics of Boletus auripes polysaccharide (BAP) are not well studied. This study aimed to investigate the influence of different digestive stages on BAP's physicochemical characteristics and biological activities, and its effect on intestinal flora. We found that mannose (0.23 %), glucose (0.31 %), galactose (0.17 %), and fucose (0.19 %) were the main monosaccharides of BAP, with a high-molecular-weight (Mw) and a low-Mw fraction of 2084.83 and 62.93 kDa, respectively. During the course of digestion, there were slight alterations in the chemical composition, monosaccharide composition, and Mw of BAP. Despite these changes, the fundamental structural features of BAP remained largely unaffected. Moreover, the antioxidant and hypoglycemic activities of BAP were weakened under simulated saliva-gastrointestinal digestion. However, gut microbiota decomposed and utilized BAP to generate various short-chain fatty acids during fermentation, which decreased the pH of fecal cultures. Meanwhile, BAP modulated the gut microbiota composition and increased the relative abundance of Bacteroidetes. These findings suggest that BAP have potential for maintaining intestinal health and protecting against interrelated diseases.

Wide-genome selection of lactic acid bacteria harboring genes that promote the elimination of antinutritional factors.

Anti-nutritional factors (ANFs) substances in plant products, such as indigestible non-starchy polysaccharides (α-galactooligosaccharides, α-GOS), phytate, tannins, and alkaloids can impede the absorption of many critical nutrients and cause major physiological disorders. To enhance silage quality and its tolerance threshold for humans as well as other animals, ANFs must be reduced. This study aims to identify and compare the bacterial species/strains that are potential use for industrial fermentation and ANFs reduction. A pan-genome study of 351 bacterial genomes was performed, and binary data was processed to quantify the number of genes involved in the removal of ANFs. Among four pan-genomes analysis, all 37 tested Bacillus subtilis genomes had one phytate degradation gene, while 91 out of 150 Enterobacteriacae genomes harbor at least one genes (maximum three). Although, no gene encoding phytase detected in genomes of Lactobacillus and Pediococcus species, they have genes involving indirectly in metabolism of phytate-derivatives to produce Myo-inositol, an important compound in animal cells physiology. In contrast, genes related to production of lectin, tannase and saponin degrading enzyme did not include in genomes of B. subtilis and Pediococcus species. Our findings suggest a combination of bacterial species and/or unique strains in fermentation, for examples, two Lactobacillus strains (DSM 21115 and ATCC 14869) with B. subtilis SRCM103689, would maximize the efficiency in reducing the ANFs concentration. In conclusion, this study provides insights into bacterial genomes analysis for maximizing nutritional value in plant-based food. Further investigations of gene numbers and repertories correlated to metabolism of different ANFs will help clarifying the efficiency of time consuming and food qualities.

Short-chain fatty acid-mediated epigenetic modulation of inflammatory T cells in vitro.

Short-chain fatty acids (SCFAs) are major metabolic products of indigestible polysaccharides in the gut and mediate the function of immune cells to facilitate homeostasis. The immunomodulatory effect of SCFAs has been attributed, at least in part, to the epigenetic modulation of immune cells through the inhibition the nucleus-resident enzyme histone deacetylase (HDAC). Among the downstream effects, SCFAs enhance regulatory T cells (Treg) over inflammatory T helper (Th) cells, including Th17 cells, which can be pathogenic. Here, we characterize the potential of two common SCFAs-butyrate and pentanoate-in modulating differentiation of T cells in vitro. We show that butyrate but not pentanoate exerts a concentration-dependent effect on Treg and Th17 differentiation. Increasing the concentration of butyrate suppresses the Th17-associated RORγtt and IL-17 and increases the expression of Treg-associated FoxP3. To effectively deliver butyrate, encapsulation of butyrate in a liposomal carrier, termed BLIPs, reduced cytotoxicity while maintaining the immunomodulatory effect on T cells. Consistent with these results, butyrate and BLIPs inhibit HDAC and promote a unique chromatin landscape in T cells under conditions that otherwise promote conversion into a pro-inflammatory phenotype. Motif enrichment analysis revealed that butyrate and BLIP-mediated suppression of Th17-associated chromatin accessibility corresponded with a marked decrease in bZIP family transcription factor binding sites. These results support the utility and further evaluation of BLIPs as an immunomodulatory agent for autoimmune disorders that are characterized by chronic inflammation and pathogenic inflammatory T cells.

Alcohol use disorder, neuroinflammation, and intake of dietary fibers: a new approach for treatment

ABSTRACT A close communication exists between the microorganisms that live in the intestine and the brain, the so-called microbiota-gut-brain axis. This interaction occurs at different levels, such as the induction by bacteria of an inflammatory state in the intestine that produces (i) stimulation of the vagus nerve that conducts information to the brain, and (ii) the release of proinflammatory cytokines – such as TNF-α- to circulation, which can then be transported to the brain and trigger neuroinflammation. Ethanol-induced neuroinflammation is produced, in part, by the impairment of the epithelial barrier function of the intestine, since acetaldehyde generated in the gut from ethanol oxidation produces a disassembly of the tight junctions (TJ), which allows diffusion of bacterial components into the blood; these events trigger a systemic inflammatory response that crosses the blood-brain barrier and induce neuroinflammation. Some short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate, are produced from indigestible polysaccharides (fibers) by certain bacteria in the microbiota. These SCFAs have shown a protective function of the TJ against intestinal injuries, preserving the intestinal barrier function. In this perspective article, we discuss the therapeutic possibility to increase the production of SCFAs in the intestine of patients with AUD, to protect the integrity of TJ and thus modulate the neuroinflammatory process that helps to the establishment of chronic alcohol intake. In this way, a new therapeutic alternative is proposed here through a simple dietary intervention in the patient, increasing their fiber consumption.

Utilisation of watermelon, pineapple and banana fruit peels as prebiotics and their effect on growth of probiotic

SummaryThis study aims to evaluate the prebiotic potential of selected fruit peels (watermelon, pineapple and banana) by studying their effects on growth of probiotic organisms as indicated by viable counts. The effect on probiotic growth was examined using different strains, namely Lactobacillus rhamnosus, L. plantarum and Bifidobacterium bifidum. The growth for L. plantarum and L. rhamnosus in pineapple peel extract (PPE) showed the maximum value of 8.27 and 7.53 log CFU/mL respectively, after 24 h incubation. The study also revealed that PPE contained the highest amounts of indigestible polysaccharides 351.13 mg/g as compared to other peels. The major reducing sugar consisted of glucose and fructose with a total amount of 442.75, 326.05 and 354.14 mg/g in dried peel extract from pineapple, watermelon and banana respectively. Pineapple and banana peel extract exhibited maximum hydrolysis of 9.21% and 8.74% and 32.95% and 30.63% when treated with gastric juice and α‐amylase. This investigation demonstrated that watermelon, pineapple and banana peel extract could be effectively used as prebiotics to improve the growth of beneficial microbes.

Bioconversion of plant wastes into feed and nutritional yeast preparations

The lack of protein in the diet of humans and animals, the presence of a large amount of plant waste, which have further potential for use, but are now almost not used, are serious problems that require immediate solutions. Modern methods of biotechnology are able to solve this issue. The purpose of this review was to study the existing technologies for using yeast to produce protein from plant waste. Waste of plant biomass, which are initially indigestible polysaccharides, when using special processing methods, break down into easily fermentable sugars, which can serve as a good substrate for the accumulation of full-fledged yeast protein, and the yeast cell wall is able to bind toxins, undesirable microorganisms and remove them from the intestinal tract of humans and animals, allowing them to be included in the composition of biologically active additives for functional purposes. The review examines the advantages of using yeast in comparison with other microorganisms and the technology of the process. It is possible to use deep and solid-phase cultivation, the first of which is technologically preferable. The products and preparations produced by foreign and domestic manufacturers are considered. Yeast is used for feed preparations:Candida, Saccharomyces, Hansenula, Torulopsis, Rhodotorula, etc.; for the food industry – mainlySaccharomices cerevisiae, Torula. The resulting products, enriched with protein and components of yeast cells, differ significantly from analogues in nutritional value. This approach to the use of industrial waste at enterprises can make many production cycles closed, increase the environmental friendliness of plants, reduce unnecessary waste disposal costs and increase total revenue.

Growing Significance of High Fiber Diet in the Prevention of Some Chronic Diseases

The unhealthy lifestyle can result in the development of chronic diseases, and the bad lifestyle affects the gastrointestinal tract, cardiovascular system or other organ systems. Chronic diseases have been encountered throughout the world. The healthy eating (70%), and exercise (30%) are the part of a proper lifestyle. The daily intake fiber is recommended as part of a healthy diet. Consuming a varied high-fiber diet means that one is getting ample of vegetables, fruits, legumes, and whole grains. Fibers are indigestible plant polysaccharides that can be water-soluble or water-insoluble. The oats and barley are good sources of water-soluble fiber whereas whole-meal grains and whole-meal breads are significant sources of water-insoluble fiber. Cereals, fruits, and vegetables are important sources of fibers. A high fiber diet contains about 40 grams of fiber and it can reduce the development of chronic diseases, such as tumors, intestinal complaints, metabolic disorders (high cholesterol level, diabetes, and obesity), and cardiovascular problems. In addition, fiber supplementation can be used as part of nutrition therapy. The manuscript focuses on the characteristics of a high fiber diet. It is hoped that our manuscript will contribute to the expansion of knowledge in the scientific society, and also provide advice to protect their health.

Polysaccharides from Cordyceps militaris prevent obesity in association with modulating gut microbiota and metabolites in high-fat diet-fed mice

Improved gut microbes and nutritious metabolites have been considered as the mediators of health benefits from indigestible polysaccharides, but their role in the anti-obesity effect of polysaccharides from Cordyceps militaris (CMP) remains elusive. This study aims to explore the potential mediators of the anti-obesity effects of CMP in high-fat diet (HFD)-fed mice using 16S rRNA sequencing and untargeted metabolomics analysis. The results showed that CMP supplementation in HFD-fed mice reduced body weight, fat accumulation, pro-inflammatory cytokine levels, and impaired glucose tolerance as well as gut barrier. Moreover, the CMP reversed the HFD-induced gut microbiota dysbiosis, as indicated by the elevated population of Alloprevotella, Parabacteroides, Butyricimonas, and Alistipes; and decreased population of Negativebacillus, in addition to altered levels of metabolites, such as brassicasterol and 4′-O-methylkanzonol W. Notably, CMP prevented obesity in association with the altered gut microbes and metabolites. These findings suggest that CMP may serve as a potential prebiotic agent to modulate specific gut microbes and related metabolites, which play a critical role in its preventing obesity-related diseases.

Rumen and lower gut microbiomes relationship with feed efficiency and production traits throughout the lactation of Holstein dairy cows

Fermentation of dietary nutrients in ruminants' gastrointestinal (GI) tract is an essential mechanism utilized to meet daily energy requirements. Especially in lactating dairy cows, the GI microbiome plays a pivotal role in the breakdown of indigestible plant polysaccharides and supply most AAs, fatty acids, and gluconeogenic precursors for milk synthesis. Although the contribution of the rumen microbiome to production efficiency in dairy cows has been widely researched over the years, variations throughout the lactation and the lower gut microbiome contribution to these traits remain poorly characterized. Therefore, we investigated throughout lactation the relationship between the rumen and lower gut microbiomes with production efficiency traits in Holstein cows. We found that the microbiome from both locations has temporal stability throughout lactation, yet factors such as feed intake levels played a significant role in shaping microbiome diversity. The composition of the rumen microbiome was dependent on feed intake. In contrast, the lower gut microbiome was less dependent on feed intake and associated with a potentially enhanced ability to digest dietary nutrients. Therefore, milk production traits may be more correlated with microorganisms present in the lower gut than previously expected. The current study's findings advance our understanding of the temporal relationship of the rumen and lower gut microbiomes by enabling a broader overview of the gut microbiome and production efficiency towards more sustainable livestock production.

Consistent Prebiotic Effects of Carrot RG-I on the Gut Microbiota of Four Human Adult Donors in the SHIME® Model despite Baseline Individual Variability.

The human gut microbiome is currently recognized to play a vital role in human biology and development, with diet as a major modulator. Therefore, novel indigestible polysaccharides that confer a health benefit upon their fermentation by the microbiome are under investigation. Based on the recently demonstrated prebiotic potential of a carrot-derived pectin extract enriched for rhamnogalacturonan I (cRG-I), the current study aimed to assess the impact of cRG-I upon repeated administration using the M-SHIME technology (3 weeks at 3g cRG-I/d). Consistent effects across four simulated adult donors included enhanced levels of acetate (+21.1 mM), propionate (+17.6 mM), and to a lesser extent butyrate (+4.1 mM), coinciding with a marked increase of OTUs related to Bacteroides dorei and Prevotella species with versatile enzymatic potential likely allowing them to serve as primary degraders of cRG-I. These Bacteroidetes members are able to produce succinate, explaining the consistent increase of an OTU related to the succinate-converting Phascolarctobacterium faecium (+0.47 log10(cells/mL)). While the Bifidobacteriaceae family remained unaffected, a specific OTU related to Bifidobacterium longum increased significantly upon cRG-I treatment (+1.32 log10(cells/mL)). Additional monoculture experiments suggested that Bifidobacterium species are unable to ferment cRG-I structures as such and that B. longum probably feeds on arabinan and galactan side chains of cRG-I, released by aforementioned Bacteroidetes members. Overall, this study confirms the prebiotic potential of cRG-I and additionally highlights the marked consistency of the microbial changes observed across simulated subjects, suggesting the involvement of a specialized consortium in cRG-I fermentation by the human gut microbiome.

Curdlan intake changes gut microbial composition, short-chain fatty acid production, and bile acid transformation in mice

Indigestible polysaccharides, such as dietary fibers, benefit the host by improving the intestinal environment. Short-chain fatty acids (SCFAs) produced by gut microbial fermentation from dietary fibers exert various physiological effects. The bacterial polysaccharide curdlan benefits the host intestinal environment, although its effect on energy metabolism and SCFA production remains unclear. Hence, this study aimed to elucidate the effect of curdlan intake on gut microbial profiles, SCFA production, and energy metabolism in a high-fat diet (HFD)-induced obese mouse model. Gut microbial composition of fecal samples from curdlan-supplemented HFD-fed mice indicated an elevated abundance of Bacteroidetes, whereas a reduced abundance of Firmicutes was noted at the phylum level compared with that in cellulose-supplemented HFD-fed mice. Moreover, curdlan supplementation resulted in an abundance of the family Bacteroidales S24-7 and Erysipelotrichaceae, and a reduction in Deferribacteres in the feces. Furthermore, curdlan supplementation elevated fecal SCFA levels, particularly butyrate. Although body weight and fat mass were not affected by curdlan supplementation in HFD-induced obese mice, HFD-induced hyperglycemia was significantly suppressed with an increase in plasma insulin and incretin GLP-1 levels. Curdlan supplementation elevated fecal bile acid and SCFA production, improved host metabolic functions by altering the gut microbial composition in mice.

Evaluation of the Inclusion of the Green Seaweed Ulva ohnoi as an Ingredient in Feeds for Gilthead Sea Bream (Sparus aurata) and European Sea Bass (Dicentrarchus labrax)

Simple SummaryThe use of seaweeds in aquafeeds is receiving increasing attention due to their potential nutritional and functional benefits. However, several green seaweeds such as Ulva presents nutritional limitations because of the undigestible polysaccharides, although these may exert a positive effect on the immunological status of the fish. The present study developed three different experiments aimed to re-evaluate the presence of protease inhibitors described for Ulva ohnoi, to assess its nutritional value as an ingredient and also to evaluate its potential protective effect on the oxidative metabolism of fish, being experiments developed in two different fish species (European sea bass Dicentrarchus labrax and gilthead sea bream, Sparus aurata). Results indicate the absence of negative effects of U. ohnoi on protein digestion of sea bream but a limited value as a feed ingredient. In contrast, its contents in bioactives seem to be correlated to the observed positive effects on the immune status and oxidative metabolism when fish are challenged by the consumption of highly oxidized dietary oil.This study evaluated the use of Ulva ohnoi as an ingredient in feeds for aquaculture in three different experiments. Experiment 1 was oriented to confirm the negative effect of U. ohnoi on fish digestion. Experiment 2 assessed the effect on growth, feed efficiency, and immune status of juvenile sea bass (Dicentrarchus labrax) fed on diets including U. ohnoi, previously treated or not with carbohydrases used to partially hydrolyze indigestible polysaccharides. Experiment 3 was aimed to evaluate the potential protective effect of U. ohnoi on the oxidative status of sea bream (Sparus aurata) challenged by the consumption of a feed formulated with the oil fraction completely oxidized. Results show a negligible effect of U. ohnoi meal on protein digestion when included in feeds at levels of 10% or less. Moreover, results of growth and feed use evidenced the possibility of using up to 5% inclusion of algal meal in feeds without adverse effects on the zootechnical parameters, while the enzyme pretreatment was ineffective to improve its nutritional use. Finally, the inclusion of U. onhoi in feeds determined both an immunostimulatory effect, evidenced by an increase in skin mucus lysozyme in the two mentioned fish species, and a positive influence on the oxidative metabolism of seabream when fed on a diet including rancid oil.

Effect of potential prebiotics from selected fruits peel on the growth of probiotics

This study aims to evaluate the potential prebiotic compounds of yellow watermelon, honeydew, and papaya peels by studying their effects on probiotics namely Lactobacillus rhamnosus and Bifidobacterium bifidum. Comparing three peel higher growth for L. rhamnosus and B. bifidum bacteria found from watermelon and honeydew which are 9.90 and 9.82 (log CFU/g dry extract) after 48 hr. Yellow watermelon peel extract also showed significantly higher amounts of indigestible polysaccharides (104.50 mg/g) than the other two peels. Glucose and fructose were the major reducing sugar present with a total of 340.34, 465.25, and 212.25 mg/g of dry peel extracts from yellow watermelon, honeydew and papaya respectively. Honeydew and yellow watermelon peel extract showed the highest hydrolysis of 13.80% and 13.68% and 11.27% and 10.53% to artificial human gastric juice and α-amylase digestion, respectively. The results indicated that among three fruit peels yellow watermelon peel shows high prebiotic potentiality. Practical applications This study found fruit peels contain a reasonably high amount of potential prebiotic compounds. The polysaccharide extracts of the peel showed a significant effect in stimulating the growth of L. rhamnosus and B. bifidum compared with the controlled study within 48 hr, where polysaccharide extract of yellow watermelon peel proving the most effective because it was able to significantly increase the probiotic bacteria count within 24 hr. In brief, yellow watermelon peel possessed the best prebiotic potential due to its high yield, quick effect in stimulating the growth of probiotic bacteria, high amount of reducing sugar, and indigestible non-starch polysaccharide while also resist digestion by gastric juice and α-amylase.

Metabolism Characteristics of Lactic Acid Bacteria and the Expanding Applications in Food Industry.

Lactic acid bacteria are a kind of microorganisms that can ferment carbohydrates to produce lactic acid, and are currently widely used in the fermented food industry. In recent years, with the excellent role of lactic acid bacteria in the food industry and probiotic functions, their microbial metabolic characteristics have also attracted more attention. Lactic acid bacteria can decompose macromolecular substances in food, including degradation of indigestible polysaccharides and transformation of undesirable flavor substances. Meanwhile, they can also produce a variety of products including short-chain fatty acids, amines, bacteriocins, vitamins and exopolysaccharides during metabolism. Based on the above-mentioned metabolic characteristics, lactic acid bacteria have shown a variety of expanded applications in the food industry. On the one hand, they are used to improve the flavor of fermented foods, increase the nutrition of foods, reduce harmful substances, increase shelf life, and so on. On the other hand, they can be used as probiotics to promote health in the body. This article reviews and prospects the important metabolites in the expanded application of lactic acid bacteria from the perspective of bioengineering and biotechnology.

Gut microbial short-chain fatty acids-mediated olfactory receptor 78 stimulation promotes anorexigenic gut hormone peptide YY secretion in mice

Olfactory receptor 78 (Olfr78), which is also known as a receptor for short-chain fatty acids (SCFAs) produced via gut microbial fermentation from indigestible polysaccharides such as dietary fibers, is expressed in the enteroendocrine cells of the colon. However, the role of Olfr78 in gut hormone secretion remains unknown. Here, we aimed to investigate the function and mechanism of action of Olfr78 in vivo and in vitro. Toward this, we assessed the expression of Olfr78 in several tissues, affinity of Olfr78 to various monocarboxylates, and the secretion of anorexigenic gut hormone peptide YY (PYY) via Olfr78 using various molecular and biochemical techniques. Olfr78 was abundantly expressed in the colon and mouse enteroendocrine cell line STC-1 and showed specific affinity to SCFAs such as acetate and propionate, but not butyrate, in a monocarboxylate ligand screening assay using a heterologous expression system. Acetate promoted PYY secretion in STC-1 cells via Olfr78-protein kinase A signaling, whereas the effects were abolished by Olfr78 RNA interference. Colonic SCFAs production via oral administration of fructo-oligosaccharide significantly increased plasma PYY levels, whereas this effect was abolished in Olfr78-deficient and germ-free mice. These results suggested that the SCFA receptor Olfr78 is important for anti-obesity and anorexigenic effects of the gut microbiota and dietary fibers.

In-depth analysis of the mechanisms of aloe polysaccharides on mitigating subacute colitis in mice via microbiota informatics

Aloe polysaccharides (APs) are indigestible bioactive polysaccharides, while can be fermented by colonic microbiota. Although plant polysaccharides can alleviate subacute ulcerative colitis (SUC), the mechanisms APs regulated SUC via colonic microbiota have not been fully explored. Hence, to elucidate the complex interactions between the novel APs, colonic microbiota, SCFAs, and inflammation, the SUC mouse model and in-depth analysis were performed, including multiple bioinformatics analysis and structural equation modeling (SEM). After APs intervention, SCFAs and SCFAs-producing genus, including Akkermansia and Blautia, were increased in colon, and the colonic inflammation and barrier dysfunction were alleviated significantly in SUC mice. Spearman analysis found positive correlations between microbiota and SCFAs. PICRUSt2 and KEGG analysis revealed 6-pyruvoyltetra hydropterin synthase in folate biosynthesis metabolism pathway was activated, while phosphotransferase system was inhibited. SEM results further proved APs was beneficial to gut micro-ecological balance in mice via SCFAs metabolism and anti-inflammatory functions. Together, APs could be exploited to alleviate SUC as dietary therapeutics.