Project description:Dietary fiber can suppress excess adipose tissue and weight gain in rodents and humans when fed high fat diets. The gut microbiome is thought to have a key role, although exactly how remains unclear. In a tightly controlled murine study, we explored how different types of dietary fiber and doses affect the gut microbiota and gut epithelial gene expression. We show that 10% pectin and 10% FOS suppress high fat diet (HFD)-induced weight gain, effects not seen at 2% doses. Furthermore, 2 and 10% mixtures of dietary fiber were also without effect. Distinct gut microbiota profiles were stimulated at the family and operational taxonomic unit (OTU) level by the different fiber treatments. Plasma levels of the gut hormone PYY were elevated by 10% pectin and FOS, but not 10% mixed fibers, and similarly RNA seq revealed some distinct effects of the 10% single fibers on gut epithelial gene expression. These data show how the ability of dietary fiber to suppress HFD-induced weight gain is dependent upon both fiber type and dose. It also shows that the microbial response to dietary fiber is distinct and that there is not a single microbial response associated with the inhibition of adiposity and weight gain. PYY seems key to the latter response, although the role of other factors such as Reg3g and CCK needs to be explored.
Project description:Alzheimer’s disease (AD) is a progressive neurodegenerative disease that becomes a major threat to the aging population. Due to lack of effective therapy, preventive treatments are important strategies to limit AD onset and progression, of which dietary patterns have been implicated as a key influencer. Diet with high fiber content is known to have beneficial effects on cognitive decline in AD. However, a global survey on brain cell dynamics in response to high fiber intake at single-cell resolution is still missing. Here, we show that dietary inulin supplementation synergized with AD progression to specifically increase the abundance of Akkermansia muciniphila in gut microbiome of the 5x Familial AD (FAD) mice. By performing single-nucleus RNA sequencing on different regions of the whole brain with three independent biological replicates, we reveal region-specific changes in the proportion of neuron, astrocyte and granule cell subpopulations upon inulin supplementation in 5xFAD mice. Intriguingly, such dietary change only marginally alleviated astrogliosis and microgliosis, without affecting the amyloid-beta plaque burden. These results provide a comprehensive overview on the transcriptomic changes in individual cells of the entire mouse brain in response to high fiber intake, which provides a resourceful foundation for future mechanistic studies on related topics
Project description:<p>Findings from recent studies suggest that the community of microbes residing in the human body is important in disease etiology; however, it remains unclear whether personal factors modulate human microbial composition. Studies based on animal models indicate that differences in composition might be attributed to sex-mediated effects. We analyzed the relationship of sex, adiposity, and dietary fiber intake with gut microbial composition using fecal samples from human subjects. We explored the associations of these factors with metrics of community composition and specific taxon abundances. We found that men and women had significantly different microbial community composition and that women had reduced abundance of a major phylum. Adiposity was associated with gut microbiome composition and specifically in women but not in men. Fiber from fruits and vegetables and fiber from beans were each associated with increased abundance of specific bacterial taxa. These findings provide initial indications that sex, adiposity, and dietary fiber might play important roles in influencing the human gut microbiome. Better understanding of these factors may have significant implications for gastrointestinal health and disease prevention.</p>
Project description:Excessive consumption of fructose leads to various cardiometabolic diseases. However, inulin, dietary fiber composed of numerous fructose molecules, exerts health-beneficial effects. Here we report that inulin shifts fructose catabolism from the host organs to gut microbiome, reversing fructose-induced hyperlipidemia, hepatic steatosis and systemic glucose intolerance. Both simultaneous and delayed inulin intake enhances fructose clearance by the small intestinal microbiome, effectively reducing fructose dose reaching the liver and colon and thus suppressing hepatic lipogenesis. Inulin also activates the hepatic de novo serine synthesis pathway and cystine uptake to augment glutathione production and reduce oxidative stress. This dual effect of inulin is blocked by antibiotics and transmittable by fecal transplantation. Moreover, inulin-enriched Bacteroides acidifaciens is protective against HFCS-induced lipogenesis. Our data provide mechanistic insights into how fructose-polymer fiber inulin rewires gut microbial fructose catabolism and protects the host from excessive fructose exposure, paving the way to mitigate fructose-induced metabolic disease.
2025-06-03 | GSE268945 | GEO
Project description:All fibers are not equal: the effect of dietary fiber on canine gut microbiome
Project description:In mammals, loss of food intake and reduced mechanical loading/activity of skeletal muscles leads to a very rapid loss in mass and function. However, during hibernation in bears, despite spending months without feeding and with very modest muscle activity, only moderate muscle wasting is observed. Part of this tissue sparing is due to a highly reduced metabolic activity in almost all tissues, including skeletal muscle. Interestingly, myosin, one of the most abundant proteins in skeletal muscle, can have different metabolic activities in inactive muscle. Therefore, to evaluate the functional and metabolic alterations in hibernating muscles, we performed an analysis on a single muscle fiber level. Individual fibers were taken from biopsies of the same bears either during hibernation or during the active phase in the summer. We confirm that muscle fibers from hibernating bears show no loss of fiber size and a mild reduction in force generating capacity. However, ATPase activity of single muscle fibers taken from hibernating bears show a significant reduction in ATPase activity, which is due to a reduced ATP turnover by myosin. By performing a single fiber proteomics analysis, we could determine in a fiber type specific manner that muscle fibers undergo a major remodeling of their proteome. Both type 2A and type 1/2A mixed fibers show a marked reduction in mitochondrial proteins during hibernation, with a decrease in proteins linked to the TCA cycle and mitochondrial translation.
Project description:Long-term dietary intake influences the structure and activity of the trillions of microorganisms residing in the human gut, but it remains unclear how rapidly and reproducibly the human gut microbiome responds to short-term macronutrient change. Here we show that the short-term consumption of diets composed entirely of animal or plant products alters microbial community structure and overwhelms inter-individual differences in microbial gene expression. The animal-based diet increased the abundance of bile-tolerant microorganisms (Alistipes, Bilophila and Bacteroides) and decreased the levels of Firmicutes that metabolize dietary plant polysaccharides (Roseburia, Eubacterium rectale and Ruminococcus bromii). Microbial activity mirrored differences between herbivorous and carnivorous mammals, reflecting trade-offs between carbohydrate and protein fermentation. Foodborne microbes from both diets transiently colonized the gut, including bacteria, fungi and even viruses. Finally, increases in the abundance and activity of Bilophila wadsworthia on the animal-based diet support a link between dietary fat, bile acids and the outgrowth of microorganisms capable of triggering inflammatory bowel disease. In concert, these results demonstrate that the gut microbiome can rapidly respond to altered diet, potentially facilitating the diversity of human dietary lifestyles. RNA-Seq analysis of the human gut microbiome during consumption of a plant- or animal-based diet.
Project description:Consumption of diets rich in fibers has been associated with several beneficial effects on gastrointestinal health. However, detailed studies on the molecular effects of fibers in colon are limited. In this study we investigated and compared the influence of five different fibers on the mucosal transcriptome, and luminal microbiota and SCFA concentrations in murine colon. Mice were fed diets enriched with fibers that differed in carbohydrate composition, namely inulin (IN), oligofructose (FOS), arabinoxylan (AX), guar gum (GG), resistant starch (RS) or a control diet (corn starch) for 10 days. Gene expression profiling revealed the regulation of specific, but also overlapping sets of epithelial genes by each fiber, which on a functional level were mainly linked to cell cycle and various metabolic pathways including fatty acid oxidation, tricarboxylic acid cycle, and electron transport chain. In addition, the transcription factor PPAR was predicted to be a prominent upstream regulator of these processes. Microbiota profiles were distinct per dietary fiber, but the fibers IN, FOS, AX and GG induced a common change in microbial groups. All dietary fibers, except resistant starch, increased SCFA concentrations but to a different extent. Multivariate data integration revealed strong correlations between the expression of genes involved in energy metabolism and the relative abundance of bacteria belonging to the group of Clostridium cluster XIVa, that are known butyrate producers. These findings illustrate the potential of multivariate data analysis to unravel simple relationships in complex systems. Keywords: Expression profiling by array Mice received a control diet, or a diet supplemented with 10% dietary fibers for 10 days. After an overnight fast colon was removed, epithelial cells were scraped off, and subjected to gene expression profiling.
Project description:Skeletal muscles are composed of a heterogeneous collection of fiber types with different physiological adaption in response to a stimulus and disease-related conditions. Each fiber has a specific molecular expression of myosin heavy chain molecules (MyHC). So far MyHCs are currently the best marker proteins for characterization of individual fiber types and several proteome profiling studies have helped to dissect the molecular signature of whole muscles and individual fibers. Herein, we describe a mass spectrometric workflow to measure skeletal muscle fiber type-specific proteomes. To bypass the limited quantities of protein in single fibers, we developed a Proteomics high-throughput Fiber Typing (ProFiT) approach enabling profiling of MyHC in single fibers. Aliquots of protein extracts from separated muscle fibers were subjected to capillary LC-MS gradients to profile MyHC isoforms in a 96-well format. Muscle fibers with the same MyHC protein expression were pooled and subjected to proteomic, pulsed-SILAC and phosphoproteomic analysis. Our fiber type-specific quantitative proteome analysis confirmed the distribution of fiber types in the soleus muscle, substantiates metabolic adaptions in oxidative and glycolytic fibers, and highlighted significant differences between the proteomes of type IIb fibers from different muscle groups, including a differential expression of desmin and actinin-3. A detailed map of the Lys-6 incorporation rates in muscle fibers showed an increased turnover of slow fibers compared to fast fibers. In addition, labeling of mitochondrial respiratory chain complexes revealed a broad range of Lys-6 incorporation rates, depending on the localization of the subunits within distinct complexes.
Project description:The investigators hypothesize that an increase in dietary fiber intake during radiation therapy may provide better long-term intestinal health for the cancer survivor. If the hypothesis is not correct, the increased intake may only mean an increase in acute side effects. All participants are advised to consume at least 16 g of dietary fiber/day via food. In addition, participants are invited to take capsules that together contain either 5.5 g of dietary fiber from psyllium husk or placebo.