Project description:Adverse changes in the gut microbiome with aging are an emerging mediator of arterial dysfunction, which contributes to cardiovascular disease (CVD) development. We investigated the therapeutic potential of enhancing the bioavailability of gut-derived short-chain fatty acids (SCFAs; produced from dietary fiber) for improving age-related arterial dysfunction. We performed gut microbial whole-genome sequencing in young (3 months) versus old (24 months) male C57BL/6N mice to explore changes in bacterial taxonomic abundance and functional pathways with aging and relations to arterial function. We then supplemented young and old mice with the SCFA acetate in drinking water versus controls and versus a high-fiber diet for 8-10 weeks to test the effects of these interventions on vascular function and explore potential mechanisms. Of the various differences in the gut microbiomes of old mice, lower SCFA-producing capacity (taxonomic abundance and functional pathways) stood out as a key feature related to worse arterial function after adjusting for age. Acetate supplementation and a high-fiber diet reversed ~30% of the age-related increase in aortic pulse wave velocity (stiffness) and fully restored carotid artery endothelium-dependent dilation (endothelial function) to young levels. Acetate and a high-fiber diet reduced age-related increases in systemic inflammation. We also found that improvements in endothelial function were likely mediated by suppressed early growth response-1 signaling using innovative siRNA-based knockdown in isolated arteries. There were no effects of the interventions in young mice. Acetate supplementation was comparably effective for ameliorating arterial dysfunction with aging as a high-fiber diet and thus shows promise for reducing CVD risk in older adults.
Project description:Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Expression of genes associated to pathogenicity is strictly regulated by environmental factors. Since short chian fatty acids (SCFAs) are present in intestinal tract which is a target of EHEC infection, we investigated the response of EHEC genes to SCFAs, such as acetate, propionate and butyrate. Keywords: Culture condition 3 sets of comparison between transcription profiles in EHEC growing in the presence of acetate, propionate or butyrate against EHEC growing in the presence of NaCl. Labelling of cDNA and hybridization were performed twice with independently prepared RNAs.
Project description:Acetate, propionate and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received relatively little attention. To investigate this aspect, we infused conscious mice with physiological quantities of stable isotopes [1-13C]acetate, [2-13C]propionate or [2,4-13C2]butyrate directly into the cecum, which is the natural production site in mice, and analyzed their interconversion by the microbiota as well as their metabolism by the host. Cecal interconversion - pointing to microbial cross-feeding - was high between acetate and butyrate, low between butyrate and propionate and almost absent between acetate and propionate. As much as 62% of infused propionate was used in whole-body glucose production, in line with its role as gluconeogenic substrate. Conversely, glucose synthesis from propionate accounted for 69% of total glucose production. The synthesis of palmitate and cholesterol in the liver was high from cecal acetate (2.8% and 0.7%, respectively) and butyrate (2.7% and 0.9%, respectively) as substrates, but low or absent from propionate (0.6% and 0.0%, respectively). Label incorporation due to chain elongation of stearate was approximately 8-fold higher than de novo synthesis of stearate. Microarray data suggested that SCFAs exert only a mild regulatory effect on the expression of genes involved in hepatic metabolic pathways during the 6h infusion period. Altogether, gut-derived acetate, propionate and butyrate play important roles as substrates for glucose, cholesterol and lipid metabolism.
Project description:Acetate, propionate and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received relatively little attention. To investigate this aspect, we infused conscious mice with physiological quantities of stable isotopes [1-13C]acetate, [2-13C]propionate or [2,4-13C2]butyrate directly into the cecum, which is the natural production site in mice, and analyzed their interconversion by the microbiota as well as their metabolism by the host. Cecal interconversion - pointing to microbial cross-feeding - was high between acetate and butyrate, low between butyrate and propionate and almost absent between acetate and propionate. As much as 62% of infused propionate was used in whole-body glucose production, in line with its role as gluconeogenic substrate. Conversely, glucose synthesis from propionate accounted for 69% of total glucose production. The synthesis of palmitate and cholesterol in the liver was high from cecal acetate (2.8% and 0.7%, respectively) and butyrate (2.7% and 0.9%, respectively) as substrates, but low or absent from propionate (0.6% and 0.0%, respectively). Label incorporation due to chain elongation of stearate was approximately 8-fold higher than de novo synthesis of stearate. Microarray data suggested that SCFAs exert only a mild regulatory effect on the expression of genes involved in hepatic metabolic pathways during the 6h infusion period. Altogether, gut-derived acetate, propionate and butyrate play important roles as substrates for glucose, cholesterol and lipid metabolism. Mice were infused in cecum with stably-labelled isotopes of the three main short chain fatty acids or control solution. After 6 hrs, livers were removed and pooled RNA samples were subjected to gene expression profiling.
Project description:Enterohaemorrhagic Escherichia coli (EHEC) is an emerging pathogen that causes diarrhea and heamolytic uremic syndrome. Expression of genes associated to pathogenicity is strictly regulated by environmental factors. Since short chian fatty acids (SCFAs) are present in intestinal tract which is a target of EHEC infection, we investigated the response of EHEC genes to SCFAs, such as acetate, propionate and butyrate. Keywords: Culture condition
Project description:Normal tissue and organ morphogenesis requires epithelial cell plasticity and conversion to a mesenchymal phenotype through a tightly regulated process-epithelial-to-mesenchymal transition (EMT). Alterations of EMT go far beyond cell-lineage segregation and contribute to pathologic conditions such as cancer. EMT is subject to intersecting control pathways; however, EMT's metabolic mechanism remains poorly understood. Here, we demonstrate that transforming growth factor β (TGF-β)-induced EMT is accompanied by decreased fatty acid oxidation (FAO) and reduced acetyl-coenzyme A (acetyl-CoA) levels. Acetyl-CoA is a central metabolite and the sole donor of acetyl groups to acetylate key proteins. Further, the short-chain fatty acid acetate increases acetyl-CoA levels--robustly inhibiting EMT and cancer cell migration. Acetate can restore EMT-associated α-tubulin acetylation levels, increasing microtubule stability. Transcriptome profiling and flow cytometric analysis show that acetate inhibits the global gene expression program associated with EMT and the EMT-associated G1 cell cycle arrest. Taken together, these results demonstrate that acetate is a potent metabolic regulator of EMT and that therapeutic manipulation of acetate metabolism could provide the basis for treating a wide range of EMT-linked pathological conditions, including cancer.
Project description:Intestinal epithelial cells and the intestinal microbiota are in a mutualistic relationship that is dependent on communication. This communication is multifaceted, but one aspect is communication through compounds produced by the microbiota such as the short-chain fatty acids (SCFAs) butyrate, propionate and acetate. Studying the effects of SCFAs and especially butyrate in intestinal epithelial cell lines like Caco-2 cells has been proven problematic. In contrast to the in vivo intestinal epithelium, Caco-2 cells do not use butyrate as an energy source, leading to a build-up of butyrate. Therefore, we used human induced pluripotent stem cell derived intestinal epithelial cells, grown as a cell layer, to study the effects of butyrate, propionate and acetate on whole genome gene expression in the cells. For this, cells were exposed to concentrations of 1 and 10 mM of the individual short-chain fatty acids for 24 hours. Unique gene expression profiles were observed for each of the SCFAs in a concentration-dependent manner. Evaluation on both an individual gene level and pathway level showed that butyrate induced the biggest effects followed by propionate and then acetate. Several known effects of SCFAs on intestinal cells were confirmed, such as effects on metabolism and immune responses. The changes in metabolic pathways in the intestinal epithelial cell layers in this study demonstrate that there is a switch in energy source from glucose to SCFAs, thus induced pluripotent stem cell derived intestinal epithelial cell are responding in a similar manner to SCFAs as in vivo intestinal tissues.
Project description:Background: Acetate, propionate, and butyrate are the main short-chain fatty acids (SCFA) produced in the colon as a result of microbial fermentation of dietary fibers. An increasing amount of evidence suggests that these SCFA have major health benefits. The composition of the microbiota is altered by dietary fat, and this is believed to impact SCFA production. Currently it is unknown whether host gene expression responses to SCFA are modulated by fat content of the diet. The aim of this study was to compare the changes in colonic gene expression profiles after acetate, propionate and butyrate infusions between a low fat and high fat diet. Methods: Male C57BL/6J mice were fed semi-synthetic low fat (10 energy%) or high fat (45 E%) diets starting 2 weeks before the SCFA treatment period. During treatment, mice received a rectal infusion of either an acetate, propionate, butyrate, or a saline (control) solution for 6 consecutive days, after which colon was subjected to gene expression profiling. Unsupervised visualization of the dataset was performed using Independent Principal Component Analysis. For each SCFA, similarities of its effects on a low fat and a high fat diet were assessed using Rank-Rank Hypergeometric Overlap. In addition, differentially expressed genes were identified, and gene set enrichment analysis was performed to determine functional implications of the regulated genes. Results: Taking into account the complete dataset, we observed that more variation in gene expression profiles was explained by fat content of the diet than by SCFA treatment. Gene expression responses to acetate and butyrate were similar on the low fat versus high fat diet, but were opposite for propionate. Functionally the expression changes reflected differential modulation of several metabolic processes; genes involved in oxidative phosphorylation, lipid catabolism, lipoprotein metabolism and cholesterol transport were suppressed by acetate and butyrate treatment, whereas propionate treatment resulted in changes in fatty acid and sterol biosynthesis, and in amino acid and carbohydrate metabolism. Conclusions: We demonstrated that dietary fat content impacts the colonic gene expression response to propionate, and to a lesser extent to acetate and butyrate. The study demonstrates that knowledge on diet composition is essential when studying effects of SCFAs on metabolism.
Project description:Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo(11)C-acetate and PET-CT scanning to show that colonic acetate crosses the blood-brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through (13)C high-resolution magic-angle-spinning that (13)C acetate from fermentation of (13)C-labelled carbohydrate in the colon increases hypothalamic (13)C acetate above baseline levels. Hypothalamic (13)C acetate regionally increases the (13)C labelling of the glutamate-glutamine and GABA neuroglial cycles, with hypothalamic (13)C lactate reaching higher levels than the 'remaining brain'. These observations suggest that acetate has a direct role in central appetite regulation.
Project description:As an important substrate for cell metabolism, the short-chain fatty acid acetate emerges as a regulator of cell fate and function. However, its role in T-cell survival and its underlying mechanisms remain largely unknown. Here, we demonstrate that acetate modulates T-cell apoptosis via potentiation of α-tubulin acetylation. We further show that acetate treatment effectively increases the expression of the tumor necrosis factor receptor (TNFR) family member CD30 by enhancing its gene transcription. Moreover, CD30 physically associates with and stabilizes the deacetylase HDAC6, which deacetylates α-tubulin to decrease microtubule stability. Proteomic profiling of CD30 knockout (Cd30-/-) T-cells reveals elevated expression of anti-apoptotic BCL2 family proteins and thus promotes T-cell survival via a microtubule-Bcl-2 axis. Taken together, our results demonstrate that acetate is a regulator of T-cell survival by controlling levels of acetylated α-tubulin. This suggests that therapeutic manipulation of acetate metabolism may facilitate optimal T-cell responses in pathological conditions.