Short-chain Fatty Acids Mixture Research Articles

Intraperitoneal Administration of Short-Chain Fatty Acids Improves Lipid Metabolism of Long-Evans Rats in a Sex-Specific Manner.

Short-chain fatty acids (SCFAs) are microbial metabolites, mainly generated by the action of gut microbiota on dietary fibers. Acetate, propionate, and butyrate are the three main SCFAs produced typically in a 60:20:20 molar ratio in the colon. Acetate, propionate, and butyrate, when given individually as supplements, have shown a protective role in obesity and hyperglycemia; however, the sex-specific effects of a mixture of SCFAs, when given in 60:20:20 ratio, on the regulation of lipid metabolism and lipid profile are not known. Male and female Long–Evans rats were given a mixture of SCFAs (acetate, propionate, and butyrate; molar ratio 60:20:20) each day for seven days intraperitoneally; plasma and hepatic lipids, gene expression, and lipidomics profile were analyzed. SCFAs significantly decreased plasma and hepatic triglycerides and cholesterol in males, whereas the fatty acyl composition of cholesteryl esters, triglycerides, and phospholipids was modulated in females. SCFAs decreased the mRNA expression of hepatic acetyl-CoA carboxylase-1 in both males and females. Our findings demonstrate for the first time that SCFAs (60:20:20) improved plasma and hepatic lipid levels and fatty acyl composition in a manner that may provide cardio-protective and anti-inflammatory effects in both sexes, via independent mechanisms.

Effect of Microbial Short-Chain Fatty Acids on CYP3A4-Mediated Metabolic Activation of Human Pluripotent Stem Cell-Derived Liver Organoids.

The early and accurate prediction of the hepatotoxicity of new drug targets during nonclinical drug development is important to avoid postmarketing drug withdrawals and late-stage failures. We previously established long-term expandable and functional human-induced pluripotent stem cell (iPSC)-derived liver organoids as an alternative source for primary human hepatocytes. However, PSC-derived organoids are known to present immature fetal characteristics. Here, we treated these liver organoids with microbial short-chain fatty acids (SCFAs) to improve metabolic maturation based on microenvironmental changes in the liver during postnatal development. The effects of the three main SCFA components (acetate, propionate, and butyrate) and their mixture on liver organoids were determined. Propionate (1 µM) significantly promoted the CYP3A4/CYP3A7 expression ratio, and acetate (1 µM), propionate (1 µM), and butyrate (1 µM) combination treatment, compared to no treatment (control), substantially increased CYP3A4 activity and albumin secretion, as well as gene expression. More importantly, mixed SCFA treatment accurately revealed troglitazone-induced hepatotoxicity, which was redeemed on a potent CYP3A4 inhibitor ketoconazole treatment. Overall, we determined, for the first time, that SCFA mixture treatment might contribute to the accurate evaluation of the CYP3A4-dependent drug toxicity by improving metabolic activation, including CYP3A4 expression, of liver organoids.

Exogenous infusion of short-chain fatty acids can improve intestinal functions independently of the gut microbiota.

The present experiment was conducted to investigate the effects of exogenously infused short-chain fatty acids (SCFAs) on the growth development and intestinal functions in a germ-free (GF) pig model. Twelve hysterectomy-derived newborn piglets were reared in six sterile isolators. All piglets were hand-fed Co60-γ-irradiated sterile milk powder for 21 d and then were switched to sterile feed for another 21 d. During the second 21-d period, GF piglets (n = 6) were orally infused with 25 mL/kg sterile saline per day, and SCFA piglets (n = 6) were orally infused with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mM, respectively) per day. We observed the concentrations of SCFAs in serum and intestine, and the messenger ribonucleic acid (mRNA) abundance of G-protein-coupled receptor-43 in the ileum was increased (P < 0.05) in the SCFA group. Meanwhile, oral infusion of SCFAs enhanced (P < 0.05) the contents of glucagon-like peptide-2 in the jejunum and serum and tended to increase the villi height in the ileum (P < 0.10). Besides, the activities of lipase, trypsin, sucrase, lactase, Na+-K+-adenosine triphosphatase ([ATPase] P < 0.05), and Ca2+-Mg2+-ATPase (P < 0.10) were stimulated and the mRNA expressions of solute carrier family 7 (SLC7A1) and regeneration protein (REG)-ΙΙΙ γ in the jejunum (P < 0.05) were upregulated in the SCFA group. Additionally, SCFAs infusion downregulated the mRNA abundances of interleukin (IL)-1β and IL-6 in the jejunum, ileum, or colon (P < 0.05) and increased the counts of white blood cell, neutrophils, and lymphocyte in the blood (P < 0.05). Collectively, exogenous infusion of SCFAs might improve intestinal health through promoting intestinal development and absorption function, and enhancing intestinal immune function, and these effects were occur independently of the gut microbiota.

High-Temperature Behavior of Early Life Membrane Models.

Origin of life scenarios generally assume an onset of cell formation in terrestrial hot springs or in the deep oceans close to hot vents, where energy was available for non-enzymatic reactions. Membranes of the protocells had therefore to withstand extreme conditions different from what is found on the Earth surface today. We present here an exhaustive study of temperature stability up to 80 °C of vesicles formed by a mixture of short-chain fatty acids and alcohols, which are plausible candidates for membranes permitting the compartmentalization of protocells. We confirm that the presence of alcohol has a strong structuring and stabilizing impact on the lamellar structures. Moreover and most importantly, at a high temperature (> 60 °C), we observe a conformational transition in the vesicles, which results from vesicular fusion. Because all the most likely environments for the origin of life involve high temperatures, our results imply the need to take into account such a transition and its effect when studying the behavior of a protomembrane model.

Atomic scale understanding of organic anion separations using ion-exchange resins

A combination of ab initio and classical molecular dynamic simulations was used to explore the adsorption/desorption and diffusion characteristics of ion-exchange resins for extraction of organic anions in electrically-driven separation processes. We considered two classes of carboxylate mixtures that are commonly encountered in bioprocessing separations: a short chain fatty acid mixture (acetate/butyrate) and an aromatic mixture (ferulate/coumarate). The suitability of several resin materials including PFC100E, IRC86, PFA444 and IRA67 was interrogated. The decomposition of the interaction energies by the symmetry-adapted perturbation theory and the classical molecular dynamic simulations of organic diffusion together reveal that the geometries of the organic anions and the functional groups of the resins, as well as their Columbic interactions, are the controlling factors in the diffusion process of the organic compounds in these resins. Classical simulations also show that modifying the functionality of resin beads, the magnitude of electric fields, and the ratio of organic mixtures may provide an effective way to control the diffusion rate and obtain selective separation of these organic mixtures. Finally, a general suggestion for favorable separation conditions is summarized.

Short-chain fatty acids (SCFAs) alone or in combination regulate select immune functions of microglia-like cells

Neuroinflammation contributes to neurodegenerative disorders, including Alzheimer's disease (AD). Gut microbes are involved in regulating systemic inflammation. Short-chain fatty acids (SCFAs), which are among the many metabolites released by gut microbes, can cross the blood-brain barrier (BBB) and interact with microglia. High concentrations of individual SCFAs decrease the inflammatory responses of peripheral monocytes; therefore, we hypothesized that SCFAs act on their own or in combinations to reduce the inflammatory response of microglia. Cultured human THP-1 monocytic cells and differentiated human HL-60 myelomonocytic cells were used to model select immune functions of human microglia. Acetate, propionate, butyrate, formate, and valerate were added to cells alone or as a mixture containing SCFAs at an approximate physiological concentration ratio. The SCFA mixture, as well as several individual SCFAs at the highest concentrations used in the mixture (15–236 μM), decreased the secretion of interleukin (IL)-1β, monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF)-α, and cytotoxins by immune-stimulated THP-1 cells. GLPG 0974, a free fatty acid receptor (FFAR) 2/3 antagonist, did not block the inhibitory effect of the SCFA mixture on IL-1β secretion by THP-1 cells while blocking the inhibitory effect of formate alone. We demonstrated that formate and valerate alone reduced the phagocytic activity of immune-stimulated THP-1 cells. Formate, but not valerate, alone also inhibited the N-formylmethionine-leucyl-phenylalanine (fMLP)-induced respiratory burst of HL-60 cells, reducing the production of reactive oxygen species (ROS). Our data indicate that SCFAs could regulate select microglial functions that are disrupted in AD.

The Production of Listeriolysin O and Subsequent Intracellular Infections by Listeria monocytogenes Are Regulated by Exogenous Short Chain Fatty Acid Mixtures.

Listeria monocytogenes is a foodborne pathogen capable of secreting listeriolysin O (LLO), a pore-forming toxin encoded by the hly gene. While the functions of LLO have been studied extensively, how the production of LLO is modulated by the intestinal environment, devoid of oxygen and enriched in short chain fatty acids (SCFAs), is not completely understood. Using L. monocytogenes strain 10403s, we found that hly transcription was moderately decreased by aerobic SCFA exposures but significantly increased by anaerobic SCFA exposures. Moreover, aerobic, but not anaerobic, exposure to low levels of SCFAs resulted in a significantly higher LLO activity. These results demonstrated that transcriptional and post-transcriptional regulations of LLO production were separately modulated by SCFAs and were responsive to oxygen levels. Examining isogenic mutants revealed that PrfA and SigB play a role in regulating LLO production in response to SCFAs. Effects of SCFAs were also present in the cardiotropic strain 07PF0776 but distinctly different from those in strain 10403s. For both strains, prior exposures to SCFAs altered intracellular infections in Caco-2 and RAW264.7 cells and the plaque sizes in L fibroblasts, a result confirming the ability of L. monocytogenes to adapt to SCFAs in ways that impact its subsequent infection outcomes.

Butyrate suppresses demyelination and enhances remyelination

BackgroundThe association of gut microbiota and diseases of the central nervous system (CNS), including multiple sclerosis (MS), has attracted much attention. Although a previous analysis of MS gut microbiota revealed a reduction in species producing short-chain fatty acids (SCFAs), the influence of these metabolites on demyelination and remyelination, the critical factors of MS pathogenesis, remains unclear.MethodsTo investigate the relationship between demyelination and gut microbiota, we administered a mixture of non-absorbing antibiotics or SCFAs to mice with cuprizone-induced demyelination and evaluated demyelination and the accumulation of microglia. To analyze the direct effect of SCFAs on demyelination or remyelination, we induced demyelination in an organotypic cerebellar slice culture using lysolecithin and analyzed the demyelination and maturation of oligodendrocyte precursor cells with or without SCFA treatment.ResultsThe oral administration of antibiotics significantly enhanced cuprizone-induced demyelination. The oral administration of butyrate significantly ameliorated demyelination, even though the accumulation of microglia into demyelinated lesions was not affected. Furthermore, we showed that butyrate treatment significantly suppressed lysolecithin-induced demyelination and enhanced remyelination in an organotypic slice culture in the presence or absence of microglia, suggesting that butyrate may affect oligodendrocytes directly. Butyrate treatment facilitated the differentiation of immature oligodendrocytes.ConclusionsWe revealed that treatment with butyrate suppressed demyelination and enhanced remyelination in an organotypic slice culture in association with facilitating oligodendrocyte differentiation. Our findings shed light on a novel mechanism of interaction between the metabolites of gut microbiota and the CNS and may provide a strategy to control demyelination and remyelination in MS.

The Effects of Short Chain Fatty Acid Mixtures on Colonic Motility

The effects of nutrients on a variety of colonic function has been well studied. Recent evidence has suggested that sensing of many different intraluminal nutrients (glucose, amino acids) is accomplished through plasma membrane receptors within the intestinal epithelium. These membrane receptors are often linked to hormone release from enteroendocrine cells. While many digested nutrients are present at higher intraluminal concentrations within the small intestine before they are absorbed, short chain fatty acids (SCFAs) in particular are generated by bacterial metabolism of nutrients within the colon. Based on previous studies, the most prominent individual SCFAs (butyrate, acetate, and propionate) have differential effects on cellular signaling and motility within the colon. However, the overall effects of mixtures of these SCFAs, which are more similar to intraluminal conditions, have not been elucidated. In this study, we measured colonic motility of both the proximal and distal colon in response to SCFA mixtures. Motility in the proximal colon of guinea pigs was measured as full‐propagating, shortpropagating, or non‐propagating contractions through video capture and subsequent generation of spatiotemporal maps. Motility in guinea pig distal colon was measured by velocity of fecal pellet propulsion. An 30mM SCFA mixture with a molar ratio of 3:2:1 (acetate: butyrate: propionate) increased velocity of fecal pellet propulsion. This increase in distal colonic motility was inhibited by GR113808, an antagonist of 5‐HT4 receptors, suggesting that mediation of motility effects was through serotonin. Statistical comparisons of pellet velocity were made by one‐way repeated measures ANOVA. In the proximal colon, the same SCFA mixture reduced the presence of short‐propagating contractions (&lt;50% of the tissue length) while not affecting full‐propagating contractions. These results suggest that SCFA mixtures have differential effects on propulsive motility in the proximal and distal colon of guinea pigs. Future work will elucidate the presence of the FFAR2 and FFAR3 receptors in relation to enteroendocrine cells containing serotonin and other endocrine mediators of colonic function (peptide YY, neurotensin).Support or Funding InformationThis work was supported by a summer research grant to DMK from Loyola University Maryland and a small grant by the VCU postdoctoral association. DMK was also partially supported by an NIGMS IRACDA grant GM093857 to VCU.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Short-Chain Fatty Acids Differentially Affect Intracellular Lipolysis in a Human White Adipocyte Model.

Gut-derived short-chain fatty acids (SCFA), formed by microbial fermentation of dietary fibers, are believed to be involved in the etiology of obesity and diabetes. Previous data from our group showed that colonic infusions of physiologically relevant SCFA mixtures attenuated whole-body lipolysis in overweight men. To further study potential mechanisms involved in the antilipolytic properties of SCFA, we aimed to investigate the in vitro effects of SCFA incubations on intracellular lipolysis and signaling using a human white adipocyte model, the human multipotent adipose tissue-derived stem (hMADS) cells. hMADS adipocytes were incubated with mixtures of acetate, propionate, and butyrate or single SCFA (acetate, propionate and butyrate) in concentrations ranging between 1 µmol/L and 1 mmol/L. Glycerol release and lipase activation was investigated during basal conditions and following β-adrenergic stimulation. SCFA mixtures high in acetate and propionate decreased basal glycerol release, when compared to control (P < 0.05), while mixtures high in butyrate had no effect. Also, β-adrenergic receptor mediated glycerol release was not significantly altered following incubation with SCFA mixtures. Incubation with only acetate decreased basal (1 µmol/L) and β-adrenergically (1 µmol/L and 1 mmol/L) mediated glycerol release when compared with control (P < 0.05). In contrast, butyrate (1 µmol/L) slightly increased basal and β-adrenergically mediated glycerol release compared with control (P < 0.05), while propionate had no effect on lipolysis. The antilipolytic effect of acetate was accompanied by a reduced phosphorylation of hormone-sensitive lipase (HSL) at serine residue 650. In addition, inhibition of Gi G proteins following pertussis toxin treatment prevented the antilipolytic effect of acetate. The present data demonstrated that acetate was mainly responsible for the antilipolytic effects of SCFA and acts via attenuation of HSL phosphorylation in a Gi-coupled manner in hMADS adipocytes. Therefore, the modulation of colonic and circulating acetate may be an important target to modulate human adipose tissue lipid metabolism.

Short-Chain Fatty Acids Suppress Inflammatory Reactions in Caco-2 Cells and Mouse Colons.

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, play an important role in the maintenance of intestinal homeostasis. In the present study, anti-inflammatory effects of SCFAs were examined in human intestinal Caco-2 cells and mouse colonic cultures. Stimulation of Caco-2 cells with tumor necrosis factor (TNF)-α induced interleukin (IL)-8 (TNF-α, 17.1 ± 7.2 vs Control, 1.00 ± 0.26, P < 0.01) and IL-6 expression (TNF-α, 21.7 ± 10.0 vs Control, 1.00 ± 0.28, P < 0.01) through the activation of nuclear factor κB p65, spleen tyrosine kinase, and mitogen-activated protein kinase pathways. Pretreatment of cells with acetate (5 mM, IL-8 1.23 ± 0.40, IL-6 2.19 ± 0.92, P < 0.01 ), propionate (2.5 mM, IL-8 2.45 ± 2.10, IL-6 2.19 ± 0.92, P < 0.01), or butyrate (0.625 mM, IL-8 1.44 ± 0.70, IL-6 2.31 ± 0.32, P < 0.01) suppressed inflammatory responses induced by TNF-α. Pharmacological inhibition of monocarboxylate transporter (MCT)-1 attenuated the suppression of inflammatory signals by SCFAs. High expression levels of CXC motif chemokine ligand 2 (CXCL2, an IL-8 homologue, DSS, 31.7 ± 9.8 vs Control, 1.00 ± 0.70, P < 0.01) and IL-6 (DSS, 17.5 ± 7.2 vs Control, 1.00 ± 0.68, P < 0.01) were observed in BALB/c mouse colonic cultures exposed to dextran sodium sulfate, whereas treatments with mixtures of SCFAs decreased these elevated expression levels (CXCL2 4.14 ± 2.88, IL-6 0.58 ± 0.28, P < 0.01). Our results suggest that SCFAs transported by MCT-1 suppress TNF-α-induced inflammatory signaling in intestinal cells.

Resolving NMR signals of short-chain fatty acid mixtures using unsupervised component analysis.

Nuclear magnetic resonance (NMR) is a very powerful instrumental technique suited to identify and characterize organic compounds. NMR has been successfully used in the analysis of complex biological and environmental samples; however, these applications are still rather limited. In this work, we describe unsupervised component analysis as a multivariate unsupervised method suited to identify the number of relevant NMR signal contributions and to deconvolve mixed signals into signal individual sources and respective contributions. Using this approach, we were able to advance further in the field of quantification of NMR spectra, and this methodology will help in the characterization of complex biological samples. Copyright © 2017 John Wiley & Sons, Ltd.

Colonic infusions of short-chain fatty acid mixtures promote energy metabolism in overweight/obese men: a randomized crossover trial

Short-chain fatty acids (SCFA), formed by microbial fermentation, are believed to be involved in the aetiology of obesity and diabetes. This study investigated the effects of colonic administration of physiologically relevant SCFA mixtures on human substrate and energy metabolism. In this randomized, double-blind, crossover study, twelve normoglycaemic men (BMI 25–35 kg/m2) underwent four investigational days, during which SCFA mixtures (200 mmol/L) high in either acetate (HA), propionate (HP), butyrate (HB) or placebo (PLA) were rectally administered during fasting and postprandial conditions (oral glucose load). Before and for two hours after colonic infusions, indirect calorimetry was performed and blood samples were collected. All three SCFA mixtures increased fasting fat oxidation (P < 0.01), whilst resting energy expenditure increased after HA and HP compared with PLA (P < 0.05). In addition, all three SCFA mixtures increased fasting and postprandial plasma peptide YY (PYY) concentrations, and attenuated fasting free glycerol concentrations versus PLA (P < 0.05). Colonic infusions of SCFA mixtures, in concentrations and ratios reached after fibre intake, increased fat oxidation, energy expenditure and PYY, and decreased lipolysis in overweight/obese men. Human intervention studies are warranted to investigate whether these effects translate into long-term benefits for body weight control and insulin sensitivity in the obese insulin resistant state.

Experimental Study of Short Chain Oils Viscosity as Biodiesel Additives

An increasing use of chemicals from biomass instead of non-renewable petrol-based ones is expected. For instance, the anaerobic digestion of organic residual streams generates many useful chemicals for the industry, together with short chain fatty acids. Another example is the biodiesel who is a suitable substitute for the non-sustainable petro-diesel. The diesel industry is mature and the biodiesel one is still under development. Oils are too viscous to be used directly in the nowadays diesel engines, producing a bad combustion. A way to reduce the viscosity of oils is to convert them into biodiesel. Biodiesel production by transesterification of non-edible oils with alcohols generates glycerol as by-product and many nowadays studies focus on providing uses to it. There are many applications for glycerol but not enough for a high biodiesel production. A way to avoid the glycerol excess is to use it in the biodiesel formulation. For instance, glycerol reacts with short chain organic acids producing short chain oils that are useful biodiesel additives. The present study determines and correlates the viscosity of short chain fatty acids (triacetin, tripropionin and tributyrin) and compares it to the viscosity of methyl oleate and solketal (another feasible biodiesel additive). The results show that short chain oils present a low enough viscosity to be used in biodiesel formulation. The viscosity model obtained is used to evaluate the viscosity of the biodiesel that would result, considering several literature experiments related to acid-genesis stages using different residual streams. The results show that the short chain fatty acids mixture obtained from any anaerobic digestion is useful as biodiesel additive. Although the short chain oil triacetin is technically a good biodiesel additive, it cannot be used in European Union due to biodiesel legal limitations on the maximum amount of triglycerides; these limitations are not present in the equivalent USA regulations.

Impact of dietary fiber‐based SCFA mixtures on colon epithelial barrier function (822.1)

Patients with HIV, obesity, and inflammatory bowel disease often have impaired gut barrier function. Short chain fatty acids (SCFAs), particularly butyrate, provide energy to the intestinal epithelium and improve barrier function. Our lab reported various fibers have different fermentation profiles, generating SCFAs varying in total concentrations and proportions of acetate, propionate, and butyrate. To study the impact of SCFA profiles of various fibers on gut barrier function, SCFA mixtures with 5, 20, and 50% butyrate proportion were designed to correspond to SCFA profiles of tested fiber fermentations, and were subjected to healthy and LPS/TNF‐α treated Caco‐2 cell monolayers. Integrity of monolayers was indicated by transepithelial electric resistance, dextran flux, and tight junction (TJ)‐related protein levels. Pro‐inflammatory genes were determined by qPCR. Total concentration of 40‐60 mM SCFA with 20% butyrate improved barrier function without causing damage to the monolayer. Within this defined concentration range of SCFAs, butyrate proportion up to 50% further promoted TJ function. Applying this result to dietary fiber selection, certain rapidly fermenting fibers may generate a high amount of SCFA that may harm gut barrier. Slow fermenting fibers that deliver appropriate concentrations of SCFAs to the epithelium with high proportion of butyrate might improve barrier function.

Fermentation in vitro of a mixture of dietary fibers and cane molasses by the cecal microbiota: Application on mineral absorption through the laying hen's colonic epithelium

Short-chain fatty acid (SCFA) production from a mixture of dietary fibers and cane molasses fermentation by laying hens’ cecal microbiota and calcium and iron absorption through the colonic mucosa driven by these acids were studied in vitro. Oligofructose, polydextrose or arabic gum at concentrations of 10g/L of cecal suspension, alone or combined with molasses in a 1:1 (w/v) relation were assayed. Fermentation of molasses and oligofructose by hens’ cecal microbiota significantly increased SCFA production; a similar effect was also observed with polydextrose and arabic gum, but to a lower extent. The highest level was attained by cecal fermentation of combined molasses–oligofructose, suggesting a complementary effect of these fibers in the mixture. SCFA mixtures with acid levels similar to that derived from the fermentation of molasses, oligofructose or a combination of both had a positive influence on mineral absorption by the colonic mucosa when assayed in an Ussing chamber. The best result was achieved with a SCFA concentration that simulated that of the molasses–oligofructose mix fermentation as the amount of calcium and iron absorbed grew approximately eightfold when compared to the one in the absence of SCFA. Different SCFA, in a range of concentrations similar to those derived from colonic fermentation without fiber addition, increased ionic absorption which was dependent on acid type and concentration used, being more remarkable for butyric acid. The effectiveness in mineral absorption was lesser than the one obtained with SCFA mixtures derived from fiber fermentations as a consequence of lower amounts of acids. The results of this study suggest that molasses–oligofructose as a layers’ diet supplement could improve mineral absorption in the intestinal lumen.

The fermented non-digestible fraction of common bean (Phaseolus vulgaris L.) triggers cell cycle arrest and apoptosis in human colon adenocarcinoma cells

Cancer is a leading cause of death worldwide with colorectal cancer (CRC) ranking as the third contributing to overall cancer mortality. Non-digestible compounds such as dietary fiber have been inversely associated with CRC in epidemiological in vivo and in vitro studies. In order to investigate the effect of fermentation products from a whole non-digestible fraction of common bean versus the short-chain fatty acid (SCFAs) on colon cancer cells, we evaluated the human gut microbiota fermented non-digestible fraction (hgm-FNDF) of cooked common bean (Phaseolus vulgaris L.) cultivar Negro 8025 and a synthetic mixture SCFAs, mimicking their concentration in the lethal concentration 50 (SCFA-LC50) of FNDF (hgm-FNDF-LC50), on the molecular changes in human colon adenocarcinoma cells (HT-29). Total mRNA from hgm-FNDF-LC50 and SCFA-LC50 treated HT-29 cells were used to perform qPCR arrays to determine the effect of the treatments on the transcriptional expression of 84 genes related to the p53-pathway. This study showed that both treatments inhibited cell proliferation in accordance with modulating RB1, CDC2, CDC25A, NFKB and E2F genes. Furthermore, we found an association between the induction of apoptosis and the modulation of APAF1, BID, CASP9, FASLG, TNFR10B and BCL2A genes. The results suggest a mechanism of action by which the fermentation of non-digestible compounds of common bean exert a beneficial effect better than the SCFA mixture by modulating the expression of antiproliferative and pro-apoptotic genes in HT-29 cells to a greater extent, supporting previous results on cell behavior, probably due to the participation of other compounds, such as phenolic fatty acids derivatives and biopetides.

Effect of short‐chain fatty acids and acidification on the phasic and tonic motor activity of the human colon

The effects of bacterial fermentation on human colonic motor activity could be explained by colonic acidification or short-chain fatty acid (SCFA) production. We compared in healthy volunteers the colonic motor effects of intracolonic infusion of neutral or acidic saline solutions and then of neutral or acidic solutions containing an SCFA mixture. 20 healthy volunteers swallowed a probe (with an infusion catheter, 6 perfused catheters and a balloon connected to a barostat) that migrated into the colon. Colonic motor activity was recorded in fasting basal state (1h), during (3h) and after (2h) intracolonic infusion in a random order on two consecutive days of 750mL of NaCl at pH 7.0 (neutral saline) or 4.5 (acidic saline) in 10 volunteers (first experiment) and of an SCFA mixture (acetic acid 66%, propionic acid 24% and butyric acid 10%; 100mM) at pH 7.0 or 4.5 in 10 other volunteers (second experiment). We determined for each hour a global motility index (reflecting phasic activity recorded by all catheters), the mean balloon volume (reflecting tonic activity), and the mean number of high-amplitude-propagated contractions (HAPCs). Intracolonic infusion of neutral or acidic solutions containing saline or an SCFA mixture did not change the global motility index, the barostat balloon volume, or the HAPC number compared with basal values. Under our experimental conditions, these findings suggest that the stimulation of colonic motor activity induced by carbohydrate fermentation is not explained by the acidification of the colonic contents or the resulting production of SCFAs.

Fermentation product of RS3 inhibited proliferation and induced apoptosis in colon cancer cell HCT-116

Cell free supernatant containing short chain fatty acid (SCFA) resulted from fermentation of resistant starch type three (RS3) by Clostridium butyricum BCC B2571 or Eubacterium rectale DSM 17629 were investigated for their ability to inhibit proliferation and induce apoptosis of human colon cancer cell line HCT-116. HCT-116 was cultured in complete medium and after 50% confluent, incubation was continued for another 48 hours in the absence or presence cell free supernatant containing SCFA mixture at butyrate levels up to 10 mM. The study revealed that the proliferation inhibition effect was higher (>80%) on HCT-116 treated with supernatant of C. butyricum BCC B2571 than that (<70%) of HCT-116 treated with supernatant of E. rectale DSM 17629. The cells were induced to undergo apoptosis by both supernatant. The apoptosis occured through mitochondrial pathway by changing the expression of gene Bcl-2 and Bax, thus incresed the Bax/Bcl-2 ratio by more than 3.5 fold. The protein caspase-3 was increased by more than 250% in the presence of the cell free supernatant.

Fermented Nondigestible Fraction from Common Bean (Phaseolus vulgaris L.) Cultivar Negro 8025 Modulates HT‐29 Cell Behavior

The aim of the study was to evaluate the effect of a fermented nondigestible fraction (FNDF) of cooked bean (Phaseolus vulgaris L.) cultivar Negro 8025 on human colon adenocarcinoma HT-29 cell survival. Negro 8025 was chosen for in vitro fermentation based on comparison of chemical composition with 2 other cultivars: Azufrado Higuera and Pinto Durango. Negro 8025 had 58% total dietary fiber, 27% resistant starch, and 20 mg of (+)-catechin equivalents per gram of sample. Short-chain fatty acids (SCFAs) production and pH of the medium were measured after fermentation as indicators of colon protection through induced arrest on cell culture and apoptosis. Butyrate and pH of FNDF of Negro 8025 were higher than the control fermented raffinose extract. The FNDF inhibited HT-29 cell survival in a time- and concentration-dependent manner. The lethal concentration 50 (LC(50)) was 13.63% FNDF (equivalent to 7.36, 0.33, and 3.31 mmol of acetic, propionic, and butyric acids, respectively). DNA fragmentation, an apoptosis indicator, was detected by the TdT-mediated dUTP nick end labeling method in cells treated with the LC(50)-FNDF and a synthetic mixture of SCFAs mimicking LC(50)-FNDF. Our results suggest that common bean is a reliable source of fermentable substrates in colon, producing compounds with potential chemoprotective effect on HT-29 colon adenocarcinoma cells, so it may present an effective alternative to mitigate colon cancer development.