Fecal Short-chain Fatty Acids Levels Research Articles

Hypoglycemic mechanism of polysaccharide from Cyclocarya paliurus leaves in type 2 diabetic rats by gut microbiota and host metabolism alteration.

Diabetes mellitus is a serious threat to human health. Cyclocarya paliurus (Batal.) Iljinskaja (C.paliurus) is one of the traditional herbal medicine and food in China for treating type 2 diabetes, and the C. paliurus polysaccharides (CP) were found to be one of its major functional constituents. This research aimed at investigating the hypoglycemic mechanism for CP. It was found that CP markedly attenuated the symptoms of diabetes, and inhibited the protein expression of Bax, improved the expression of Bcl-2 in pancreas of diabetic rats, normalized hormones secretion and controlled the inflammation which contributed to the regeneration of pancreatic β-cell and insulin resistance. CP treatment increased the beneficial bacteria genus Ruminococcaceae UCG-005 which was reported to be a key genus for protecting against diabetes, and the fecal short-chain fatty acids levels were elevated. Uric metabolites analysis showed that CP treatment helped to protect with the diabetes by seven significantly improved pathways closely with the nutrition metabolism (amino acids and purine) and energy metabolism (TCA cycle), which could help to build up the intestinal epithelial cell defense for the inflammation associated with the diabetes. Our study highlights the specific mechanism of prebiotics to attenuate diabetes through multi-path of gut microbiota and host metabolism.

Dysbiosis of Gut Microbiota and Short-Chain Fatty Acids in Acute Ischemic Stroke and the Subsequent Risk for Poor Functional Outcomes.

BackgroundThe intestinal microbiota and its metabolites have been reported to play an important role in stroke. Gut microbiota–originating short‐chain fatty acids (SCFAs) modulate brain functions directly or indirectly through immune, endocrine, vagal, and other humoral pathways. However, relatively few investigations have evaluated the gut microbiome and SCFAs spectrum or their potential associations with stroke outcomes in acute ischemic stroke (AIS) patients with different stroke severities.MethodsWe used 16S rRNA gene sequencing and gas chromatography to compare the fecal microbial composition and SCFA spectrum between AIS patients (n = 140) and healthy controls (n = 92). Their associations with 90‐day poor functional outcomes were evaluated by logistic regression models.ResultsWe found that the intestinal microbiota distinguished AIS patients from healthy controls. A lack of SCFAs‐producing bacteria and a low fecal SCFAs level defined dysbiosis in AIS patients, especially those with increased stroke severity. The SCFAs levels were negatively correlated with stroke severity and prognosis. Reduced SCFAs levels, especially acetate, were associated with an increased risk of 90‐day poor functional outcomes even after adjustments.ConclusionsDysbiosis of SCFAs‐producing bacteria and SCFAs in AIS patients increased the subsequent risk for poor functional outcomes, indicating that SCFAs could be potential prognostic markers and therapeutic targets for stroke.

Almonds Improve Endothelial Function and Lower LDL Cholesterol, But Do Not Affect Liver Fat in Adults at Moderate Risk of Cardiovascular Disease: A Randomized Controlled Trial

Abstract Objectives The ATTIS study aimed to investigate whether substituting almonds for typical snacks (high in refined starch, free sugars and saturated fats, and low in fibre) influenced cardiometabolic risk factors. Primary outcomes, endothelial function and liver fat, were measured in healthy adults aged 30–70 y who were habitual snackers and at moderate risk of developing cardiovascular disease (CVD). It was hypothesized that snacking on almonds would improve endothelial function and decrease liver fat. Methods Following a 2-week run-in period consuming control snacks, a 6-week parallel arm trial was conducted where participants were randomized to isoenergetic treatments: 1) control snacks (mini-muffins) replicating an average snack nutrient profile, calculated from snack foods identified in 4-d food diaries from a national dietary intake database, or 2) dry-roasted whole almonds, providing 20% estimated energy requirement. Endothelial function (via flow-mediated dilation (FMD)); abdominal subcutaneous and visceral fat, and liver, muscle and pancreatic fat (via MRI/MRS); day- and night-time heart rate variability (HRV) and 24 h ambulatory blood pressure (ABP); blood biomarkers of insulin sensitivity and lipid profile; and fecal short chain fatty acids (SCFA) were assessed at baseline and endpoint. A total of 107 participants (75 F, 32 M; mean age 56.2 y, SD 10.4) were randomized and 105 subjects completed the trial. Results Almonds significantly increased FMD (mean difference 4.1%, 95% CI 2.2, 5.9), the long-phase HRV index, night-time very-low frequency power (mean difference 337 ms2, 95% CI 12, 661) and plasma oleic acid levels (mean difference 228 μmol, 95% CI 7, 449) relative to control adjusted for baseline BMI and baseline dependent outcome values, but there were no treatment differences in ABP and subcutaneous, visceral, liver, muscle and pancreatic fat. Plasma LDL cholesterol levels were significantly decreased by almonds (mean difference −0.25 mmol/L, 95% CI −0.45, −0.04), but no differences were found in other blood lipids, insulin sensitivity, nor fecal SCFA levels. Conclusions These novel findings suggest almonds may be cardioprotective by increasing availability of nitric oxide and improving cardiac autonomic function, in addition to their well-established LDL cholesterol-lowering properties. Funding Sources Almond Board of California.

An Overview on Fecal Branched Short-Chain Fatty Acids Along Human Life and as Related With Body Mass Index: Associated Dietary and Anthropometric Factors.

Short-chain fatty acids (SCFA) are the main bacterial products of the catabolism of carbohydrates and proteins in the gut, and their role is essential in host–microbiota interactions. Acetic, propionic, and butyric acids are the major SCFA produced in the gut, and they have been extensively studied. In contrast, branched short-chain fatty acids (BCFA), mainly isovaleric and isobutyric acids, are produced in less amounts and their fecal levels in different human groups, intestinal microbial producing populations, and influence on health are insufficiently known. They have been proposed as markers of protein fermentation, which leads to the concomitant production of other fermentation products that can be harmful for the colon epithelium. In this context, the aim of this study was to shed light into the production of BCFA by the human intestinal microbiota, as related to age, body mass index (BMI), and diet. Fecal levels of the different SCFA were analyzed by gas chromatography in 232 healthy individuals with ages between 3 months and 95 years, and BMI in adults ranging from 19 to 54. Dietary assessments in adults were obtained through a food frequency questionnaire (FFQ). Molar proportions of BCFA in feces were strongly and positively related with aging. However, not a significant relationship was obtained between BCFA and BMI. A negative correlation was found between the consumption of dietary insoluble fiber and fecal levels of BCFA. More studies are needed for improving our understanding on the relationship of BCFA production profile with the intestinal microbiota composition and human health.

Protective effect of baicalin on the regulation of Treg/Th17 balance, gut microbiota and short-chain fatty acids in rats with ulcerative colitis.

Baicalin is reported as an effective drug for ulcerative colitis (UC). However, its effect on gut microbiota and short-chain fatty acids (SCFAs) remains unknown. In this study, we investigated the role of baicalin on Th17/Treg balance, gut microbiota community, and SCFAs levels in trinitrobenzene sulphonic acid (TNBS)-induced UC rat model. We found the DAI scores were significantly increased in the TNBS-treated rats, while reduced in the baicalin-treated group in a dose-dependent manner, accompanied with the alleviation of mucosal injury, the reduction of ZO-1, Occludin, and MUC2 expression. At the meanwhile, baicalin repressed the increased levels of reactive oxygen species (ROS) and MDA, while deceased the GSH and SOD levels in colon tissue of rats treated with TNBS. On the other hand, administration of baicalin attenuated the TNBS-induced upregulations of Th17/Treg ratio, indicating a strong amelioration in the colorectal inflammation. More importantly, pyrosequencing of the V4 regions of 16S rRNA genes in rat feces revealed a deviation of the gut microbiota in response to baicalin treatment. In particular, the decreased Firmicutes-to-Bacteroidetes ratios and endotoxin-bearing Proteobacteria levels indicated that baicalin reversed TNBS-induced gut dysbiosis OTUs. In addition, we further investigated the fecal levels of major SCFAs in rats and found that baicalin significantly resorted the fecal butyrate levels in rats treated with TNBS. The increased butyrate levels were in consistent with the higher abundance of butyrate-producing species such as Butyricimonas spp., Roseburia spp., Subdoligranulum spp., and Eubacteriu spp. in baicalin-treated group. In conclusion, our findings suggest that baicalin possibly protected rats against ulcerative colitis by regulation of Th17/Treg balance, and modulation of both gut microbiota and SCFAs. Baicalin may be used as a prebiotic agent to treat ulcerative colitis-associated inflammation and gut dysbiosis.

Consumption of young barley leaf extract increases fecal short-chain fatty acid levels: a before-after clinical trial

Short-chain fatty acids (SCFAs) bacterially produced in the intestine provide a variety of physiological effects for the host. The present before-after clinical trial was conducted to investigate the effects of young barley leaf extract (YBL) on fecal SCFA levels. For 4 weeks, female health subjects were asked to ingest two sticks (8 g) of test sample daily. Feces were collected before and after the period of treatment with YBL. Results demonstrated that YBL significantly elevated the fecal concentrations of acetate from 23.6±7.5 to 36.4±8.1 μmol/g (p<0.001) and propionate from 10.0±5.2 to 13.6±7.1 μmol/g (p<0.05) but, did not give an advantage in fecal bacterial composition. Interestingly, YBL also raised the fecal moisture by 3.9% point from the baseline (p<0.05).

Towards a psychobiotic therapy for depression: Bifidobacterium breve CCFM1025 reverses chronic stress-induced depressive symptoms and gut microbial abnormalities in mice

BackgroundAccumulating evidence points to an association between gut microbial abnormalities and depression disorder. The microbiota-gut-brain axis is an emerging target for treating depression using nutritional strategies, considering the numerous limitations of current pharmacological approaches. Here we studied the effect and probable mechanisms of psychobiotic treatment on depression. MethodsChronically stressed C57BL/6J male mice were administered viable Bifidobacterium breve CCFM1025 for 5 weeks prior to behavioral testing. Brain neurological alterations, serum corticosterone, cytokines levels, fecal microbial composition, and short-chain fatty acid (SCFA) content were measured. In addition, the effect of SCFA on 5-hydroxytryptophan (5-HTP) biosynthesis was investigated in an in vitro model of enterochromaffin cells (RIN14B). ResultsCCFM1025 treatment significantly reduced depression- and anxiety-like behaviors. The hyperactive hypothalamic-pituitary-adrenal response, as well as inflammation, were also alleviated, possibly via regulating the expression of glucocorticoid receptors (Nr3c1). Moreover, CCFM1025 also down-regulated the pCREB-c-Fos pathway but increased the expression of brain-derived neurotrophic factor (BDNF). Meanwhile, chronic stress-induced gut microbial abnormalities were restored, accompanied by increased SCFA and 5-HTP levels. The intestinal 5-HTP biosynthesis positively correlated with fecal SCFA and Bifidobacterium breve levels. ConclusionsIn summary, Bifidobacterium breve CCFM1025 showed considerable antidepressant-like and microbiota-regulating effects, which opens avenues for novel therapeutic strategies towards treating depression.

Changes in Faecal Short-Chain Fatty Acids after Weight-Loss Interventions in Subjects with Morbid Obesity.

The gut microbiota and their metabolites, e.g., short-chain fatty acids (SCFA), are associated with obesity. The primary aims were to study faecal SCFA levels and the changes in SCFA levels after weight-loss interventions in subjects with obesity, and secondarily, to study factors associated with the faecal SCFA levels. In total, 90 subjects (men / women: 15/75) with a mean age of 44.4 (SD 8.4) years, BMI 41.7 (SD 3.7) kg/m2 and morbid obesity (BMI > 40 or > 35 kg/m2 with obesity-related complications) were included. Faecal SCFA and other variables were measured at inclusion and after a six-month conservative weight-loss intervention followed by bariatric surgery (Roux-en-Y gastric bypass or gastric sleeve). Six months after surgery, the total amount of SCFA was reduced, the total and relative amounts of the main straight SCFA (acetic-, propionic-, and butyric- acids) were reduced, and the total and relative amounts of branched SCFA (isobutyric-, isovaleric-, and isocaproic- acids) were increased. The changes indicate a shift toward a proteolytic fermentation pattern with unfavorable health effects. The amount of SCFA was associated with the diet but not with metabolic markers or makers of the faecal microbiota composition. Dietary interventions could counteract the unfavorable effects.

Short-chain fatty acids accompanying changes in the gut microbiome contribute to the development of hypertension in patients with preeclampsia.

Preeclampsia (PE) is regarded as a pregnancy-associated hypertension disorder that is related to excessive inflammatory responses. Although the gut microbiota (GM) and short-chain fatty acids (SCFAs) have been related to hypertension, their effects on PE remain unknown. We determined the GM abundance and faecal SCFA levels by 16S ribosomal RNA (rRNA) sequencing and gas chromatography, respectively, using faecal samples from 27 patients with severe PE and 36 healthy, pregnant control subjects. We found that patients with PE had significantly decreased GM diversity and altered GM abundance. At the phylum level, patients with PE exhibited decreased abundance of Firmicutes albeit increased abundance of Proteobacteria; at the genus level, patients with PE had lower abundance of Blautia, Eubacterium_rectale, Eubacterium_hallii, Streptococcus, Bifidobacterium, Collinsella, Alistipes, and Subdoligranulum, albeit higher abundance of Enterobacter and Escherichia_Shigella. The faecal levels of butyric and valeric acids were significantly decreased in patients with PE and significantly correlated with the above-mentioned differential GM abundance. We predicted significantly increased abundance of the lipopolysaccharide (LPS)-synthesis pathway and significantly decreased abundance of the G protein-coupled receptor (GPCR) pathway in patients with PE, based on phylogenetic reconstruction of unobserved states (PICRUSt). Finally, we evaluated the effects of oral butyrate on LPS-induced hypertension in pregnant rats. We found that butyrate significantly reduced the blood pressure (BP) in these rats. In summary, we provide the first evidence linking GM dysbiosis and reduced faecal SCFA to PE and demonstrate that butyrate can directly regulate BP in vivo, suggesting its potential as a therapeutic agent for PE.

Fecal Short-Chain Fatty Acids Levels Were Not Associated With Autism Spectrum Disorders in Chinese Children: A Case-Control Study.

Evidence from animal models supports a link between short-chain fatty acids (SCFAs), a key subset of gut microbial metabolites, and autism spectrum disorders (ASD). However, findings from human studies on this topic are unclear. We aimed to investigate whether fecal SCFAs are associated with ASD in Chinese children aged 6–9 years old. A total of 45 ASD children aged 6–9 years and 90 sex- and age-matched neurotypical controls were enrolled. High-performance liquid chromatography was applied to quantify 10 SCFA subtypes in feces. Dietary and other socio-demographic information were obtained via face-to-face interview using questionnaires. After adjustment for multiple comparisons, paired t-test analysis indicated that the fecal total and subtype SCFA concentrations were comparable in autistic children and the controls. Conditional logistic regression analysis showed that there was no significant relationship between the fecal concentration of SCFAs and the risk of ASD after adjustment for age, sex, BMI, breastfeeding, mode of delivery, parental education level, and daily energy, protein, fat, and fiber intake. In conclusion, our results did not support the hypothesis that fecal SCFA levels might be associated with the presence of ASD. However, SCFA measurement was based on a single stool sample test, so this conclusion should be treated with caution. Further studies with measurement of long-term bodily SCFA concentrations are needed to examine this relationship.

Effects of Rice with Different Amounts of Resistant Starch on Mice Fed a High-Fat Diet: Attenuation of Adipose Weight Gain.

Increasing the amount of resistant starch (RS) in the diet may confer protective effects against chronic diseases. Rice, a good dietary source of carbohydrates, also contains RS. However, it remains unclear if RS at the amount consumed in cooked rice has a health benefit. To address the question, we examined the effects of cooked rice containing different levels of RS in a diet-induced obesity rodent model. Rice containing RS as low as 1.07% attenuated adipose weight and adipocyte size gain, induced by a moderately high-fat (HF) diet, which correlated with lower leptin levels in plasma and adipose tissue. Rice with 8.61% RS increased fecal short-chain fatty acid levels, modulated HF-diet-induced adipose triacylglycerol metabolism and inflammation-related gene expression, and increased fecal triglyceride excretion. Hence, including rice with RS level at ≥1.07% may attenuate risks associated with the consumption of a moderately HF diet.

SUN-303 DIETARY MANIPULATION OF THE GUT MICROBIOTA REDUCES DIABETIC KIDNEY INJURY IN MICE

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease (CKD) globally. High dietary fibre intake has been associated with decreased inflammation and mortality in CKD. Short-chain fatty acids (SCFA) derived from gut microbial fermentation of dietary fibre are thought to regulate gut and systemic inflammation. Here we evaluated the effect of dietary modification, or supplementation with the three main SCFAs (acetate, propionate, butyrate) on the development of DN in a mouse model of streptozotocin (STZ) induced diabetes. Diabetes was induced using a low dose STZ protocol in C57BL/6 mice. Three weeks after STZ injection, diabetic mice were switched to a zero-fibre (ZF) or high-fibre (HF) diet, whilst control diabetic mice remained on the normal diet. For mechanistic studies, two-weeks after STZ, groups of diabetic mice received daily intra-peritoneal injections of either sodium acetate (SA), propionate (SP), butyrate (SB) 200mg/kg or saline for 2 weeks, then switched to oral SCFAs (SA 150mM, SP 100mM, SB 50mM, or pH and sodium-matched water) in their drinking water for the duration of the study. Blood, urine and kidneys were collected after 12 weeks. All STZ-treated mice developed diabetes within two weeks. Diet altered the gut microbiome in diabetic mice, with significant preservation of diversity evident in HF compared to ZF mice. As compared to ZF and normal diets, HF fed mice had higher faecal SCFA levels (>2-fold, p<0.05) and serum acetate concentrations (>3-fold, p<0.001). HF fed mice were protected from DN, with a reduction in albuminuria of 50% (p<0.01), reduced kidney to body weight ratio (1.33 vs 2.4, p<0.0001), glomerular hypertrophy (22±17.5 vs 35.5±15.3 (x104 μm3), p<0.0001), glomerular cellularity (24.9±1.7 vs 36.6±1.7, p<0.0001), interstitial fibrosis (p<0.0001) and podocyte injury (p<0.0001) compared to diabetic controls on normal or ZF diets. Treatment of diabetic mice with SA, SP or SB achieved similar degrees of protection to the HF-diet, with less glomerular hypertrophy (p<0.01), podocyte injury (p<0.05), interstitial fibrosis (p<0.001) and interstitial macrophage accumulation (p<0.01), as compared to diabetic controls. Albuminuria was also reduced by over 50% (p<0.05). mRNA expression of cytokines (IL6, TGF-β), chemokine (CCL2) and pro-fibrotic (fibronectin) genes in the kidney were attenuated in SA treated diabetic mice versus controls (p<0.05). Treatment with dietary fibre supplementation provides protection against development of DN through modulation of the gut microbiota with increased gastrointestinal release and systemic distribution of SCFAs. SCFA treatment was similarly protective, supporting SCFAs as a key mediator of the beneficial effects of the HF diet. Manipulation of the gastrointestinal microbiota through diet may be a novel strategy in prevention and management of diabetic nephropathy.

The combination of wheat peptides and fucoidan protects against chronic superficial gastritis and alters gut microbiota: a double-blinded, placebo-controlled study.

Chronic gastritis is observed in almost half world population. Traditional medications against chronic gastritis might produce adverse effects, so alternative nutritional strategies are needed to prevent the aggravation of gastric mucosal damage. The aim of this study is to evaluate the protective effect of the combination of wheat peptides and fucoidan (WPF) on adults diagnosed with chronic superficial gastritis in a randomized, double-blind, placebo-controlled clinical trial. Participants were randomized to receive WPF (N = 53) or placebo (N = 53) once daily for 45days. Pathological grading of gastric mucosal damage was scored using gastroscopy. Fecal samples were collected for the determination of calprotectin, short chain fatty acids (SCFA) levels and metagenomics analysis. Questionnaires for self-reported gastrointestinal discomforts, life quality and food frequency were collected throughout the study. WPF intervention reduced gastric mucosal damage in 70% subjects (P < 0.001). Significantly less stomach pain (P < 0.001), belching (P = 0.028), bloating (P < 0.001), acid reflux (P < 0.001), loss of appetite (P = 0.021), increased food intake (P = 0.020), and promoted life quality (P = 0.014) were reported in the WPF group. WPF intervention significantly decreased fecal calprotectin level (P = 0.003) while slightly increased fecal SCFAs level (P = 0.092). In addition, we found altered microbiota composition post-intervention with increased Bifidobacterium pseudocatenulatum (P = 0.032), Eubacterium siraeum (P = 0.036), Bacteroides intestinalis (P = 0.024) and decreased Prevotella copri (P = 0.055). WPF intervention could be utilized as a nutritional alternative to mitigate the progression of chronic gastritis. Furthermore, WPF played an important role in altering gut microbial profile and SCFA production, which might benefit the lower gastrointestinal tract.

The Combination of Wheat Peptides and Fucoidan Protects Against Chronic Superficial Gastritis and Regulates Gut Microbiota: A Double-blinded, Placebo-controlled Study (P06-104-19)

ObjectivesChronic gastritis is observed in almost half world population. Traditional medications against chronic gastritis might produce adverse effects, so alternative nutritional strategies are needed to prevent the aggravation of gastric mucosal damage. The aim of this study is to evaluate the protective effect of the combination of wheat peptides and fucoidan (WPF) on adults diagnosed with chronic superficial gastritis in a randomized, double-blind, placebo-controlled clinical trial. MethodsParticipants were randomized to receive WPF (N = 53) or placebo (N = 53) once daily for 45 days. The pathological grading of gastric mucosal damage was scored using gastroscopy. The fecal samples were collected for the determination of calprotectin, short-chain fatty acids (SCFA) levels and metagenomics analysis. The questionnaires for self-reported gastrointestinal discomforts, life quality and food frequency were collected throughout the study. ResultsWPF intervention reduced gastric mucosal damage of subjects (P < 0.001). Significantly less stomach pain (P < 0.001), belching (P = 0.028), bloating (P < 0.001), acid reflux (P < 0.001), loss of appetite (P = 0.021), increased food intake (P = 0.020), and promoted life quality (P = 0.014) were reported in the WPF group. WPF intervention significantly decreased fecal calprotectin level (P = 0.003) while slightly increased fecal SCFAs level (P = 0.092). Mechanistically, we found a shifted microbiota profile post-intervention with significantly increased bifidobacterium pseudocatenulatum (P = 0.032), eubacterium siraeum (P = 0.036), bacteroides intestinalis (P = 0.024) and decreased prevotella copri (P = 0.055). ConclusionsIn conclusion, WPF intervention could be utilized as a nutritional alternative to reverse the progression of chronic gastritis. Furthermore, WPF played an important role in the regulation of gut microbiota and SCFA production, which might benefit the lower gastrointestinal tract. Funding SourcesNutrilite Health Institute funded this research. Supporting Tables, Images and/or Graphs▪

Mitigation of Colonic Inflammation in Dextran Sulfate Sodium-treated Mice by Dietary Supplementation with Soybean Fiber (P06-079-19)

ObjectivesSoybean fiber (SBF) is an insoluble, but highly fermentable dietary fiber. Previous in vitro fermentation studies with human feces have shown that SBF produces 1.5–8 times more acetate, propionate, and butyrate than oat bran, corn bran, or wheat bran fiber. Short chain fatty acids (SCFA) have been reported to play a key role in maintaining colon health and reducing inflammation. The impact of dietary SBF on colonic inflammation has not previously been examined. Our objective was to determine the anti-inflammatory efficacy of dietary supplementation with SBF in a mouse model of acute colonic inflammation. MethodsMale C57BL/6 J mice (5 weeks old) were randomized to AIN93G diet (CTL) or diet where 40% of the fiber was replaced with SBF (SBF-Hi). After 2 weeks of pretreatment, mice were given 2% dextran sulfate sodium (DSS) as the sole source of drinking fluid for 1 week to induce colonic inflammation. During DSS treatment, mice were maintained on their diet treatments. After DSS treatment, mice were euthanized and colonic inflammation was assessed. ResultsDSS-treated mice had significantly larger spleens and shorter colons than mice treated with water. SBF-Hi mitigated DSS-induced increases in spleen weight (20% lower) and colon shortening (15% longer). Quantitative, reverse transcriptase PCR analysis showed that DSS-treatment increased colonic mRNA expression of interleukin-6 (Il6) and tumor necrosis factor-a (Tnfa) by 3-fold compared to water-treated mice. Dietary supplementation with SBF blunted these increases in Il6 and Tnfa by 87% and 71%, respectively. ConclusionsOur results suggest that dietary supplementation with SBF may be a useful approach to mitigate colonic inflammation. On-going studies are focused on determining fecal levels of SCFA and measuring protein markers of inflammation and gut barrier function. Future studies are needed to evaluate whether the protective effects observed in this study are maintained in situations of more chronic colonic inflammation. Funding SourcesThis work was funded by a grant from the Pennsylvania Soybean Board and by USDA National Institute of Food and Agriculture Appropriations under Project PEN04565.

Navy bean supplemented high-fat diet improves intestinal health, epithelial barrier integrity and critical aspects of the obese inflammatory phenotype

Obesity is associated with impaired intestinal epithelial barrier function and an altered microbiota community structure, which contribute to host systemic inflammation and metabolic dysfunction. Fiber-rich common beans (Phaseolus vulgaris) promote intestinal health (microbiota and host epithelial barrier integrity) in lean mice. The objective was to assess the intestinal health promoting effects of navy bean supplementation during high-fat (HF)diet-induced obesity. Male C57BL/6 mice were fed either a high-fat (HF) diet (60% of kcal from fat) or an isocaloric HF diet supplemented with 15.7% (by weight) cooked navy bean powder (HF+B) for 12 weeks. Compared to HF, the HF+B diet altered the fecal microbiota community structure (16S rRNA gene sequencing), most notably increasing abundance of Akkermansia muciniphila (+19-fold), whose abundance typically decreases in obese humans and rodents. Additionally, HF+B fecal abundance of carbohydrate fermenting, short chain fatty acid (SCFA) producing Prevotella (+332-fold) and S24–7 (+1.6-fold) and fecal SCFA levels were increased. HF+B improved intestinal health and epithelial barrier integrity versus HF, evidenced by reduced serum fluorescein isothiocyanate (FITC)-dextran concentration in an in vivo gut permeability test, and increased intestinal mRNA expression of tight junction components (ZO-1, occludin), anti-microbial defenses (Reg3γ, IgA, Defα5, Defβ2) and mucins (Muc2). Additionally, HF+B improved the systemic obese phenotype via reduced serum HOMA-IR and leptin:adiponectin ratio, and locally via attenuation of epididymal adipose tissue crown-like structure formation, adipocyte size, and inflammatory transcription factor (NFκBp65 and STAT3) activation. Therefore, navy bean supplementation improved obese intestinal health (microbiota and epithelial barrier integrity) and attenuated the severity of the obese phenotype.

Quantification of Fecal Short Chain Fatty Acids by Liquid Chromatography Tandem Mass Spectrometry-Investigation of Pre-Analytic Stability.

Short chain fatty acids (SCFAs) are generated by the degradation and fermentation of complex carbohydrates, (i.e., dietary fiber) by the gut microbiota relevant for microbe–host communication. Here, we present a method for the quantification of SCFAs in fecal samples by liquid chromatography tandem mass spectrometry (LC-MS/MS) upon derivatization to 3-nitrophenylhydrazones (3NPH). The method includes acetate, propionate, butyrate, and isobutyrate with a run time of 4 min. The reproducible (coefficients of variation (CV) below 10%) quantification of SCFAs in human fecal samples was achieved by the application of stable isotope labelled internal standards. The specificity was demonstrated by the introduction of a quantifier and qualifier ions. The method was applied to investigate the pre-analytic stability of SCFAs in human feces. Concentrations of SCFA may change substantially within hours; the degree and kinetics of these changes revealed huge differences between the donors. The fecal SCFA level could be preserved by the addition of organic solvents like isopropanol. An analysis of the colon content of mice either treated with antibiotics or fed with a diet containing a non-degradable and -fermentable fiber source showed decreased SCFA concentrations. In summary, this fast and reproducible method for the quantification of SCFA in fecal samples provides a valuable tool for both basic research and large-scale studies.

Intestinal short-chain fatty acid composition does not explain gut microbiota-mediated effects on malaria severity.

Malaria is a devastating disease resulting in significant morbidity and mortality, especially in the developing world. Previously, we showed that the gut microbiome modulates severity of malaria in mice, though the exact mechanism was unknown. One well-studied mechanism by which the intestinal microbiota exerts an effect on host health is by synthesis of short-chain fatty acids (SCFAs). SCFAs have pleiotropic effects on the host, including modulating the immune system and altering susceptibility to pathogens. The objective of the current work was to explore if gut microbiota-mediated resistance and susceptibility to malaria in mice is through differential production of SCFAs. Of the eight detected SCFAs, only propionic acid (C3) was different between two groups of resistant and two groups of susceptible mice, with higher levels in feces of susceptible mice compared to resistant mice. Nevertheless, subsequent analysis revealed no robust correlation between malaria severity and levels of fecal propionic acid. In spite of the broad effect of SCFAs on host physiology, including host immunity, this study shows that gut microbiota-mediated modulation of malaria severity in mice is independent of fecal SCFA levels. Additionally, our data indicates that intestinal SCFAs do not function as biomarkers for prediction of malaria disease severity.

Short Chain Fatty Acids (SCFAs)-Mediated Gut Epithelial and Immune Regulation and Its Relevance for Inflammatory Bowel Diseases.

Ulcerative colitis (UC) and Crohn's disease (CD), collectively known as Inflammatory Bowel Diseases (IBD), are caused by a complex interplay between genetic, immunologic, microbial and environmental factors. Dysbiosis of the gut microbiome is increasingly considered to be causatively related to IBD and is strongly affected by components of a Western life style. Bacteria that ferment fibers and produce short chain fatty acids (SCFAs) are typically reduced in mucosa and feces of patients with IBD, as compared to healthy individuals. SCFAs, such as acetate, propionate and butyrate, are important metabolites in maintaining intestinal homeostasis. Several studies have indeed shown that fecal SCFAs levels are reduced in active IBD. SCFAs are an important fuel for intestinal epithelial cells and are known to strengthen the gut barrier function. Recent findings, however, show that SCFAs, and in particular butyrate, also have important immunomodulatory functions. Absorption of SCFAs is facilitated by substrate transporters like MCT1 and SMCT1 to promote cellular metabolism. Moreover, SCFAs may signal through cell surface G-protein coupled receptors (GPCRs), like GPR41, GPR43, and GPR109A, to activate signaling cascades that control immune functions. Transgenic mouse models support the key role of these GPCRs in controlling intestinal inflammation. Here, we present an overview of microbial SCFAs production and their effects on the intestinal mucosa with specific emphasis on their relevance for IBD. Moreover, we discuss the therapeutic potential of SCFAs for IBD, either applied directly or by stimulating SCFAs-producing bacteria through pre- or probiotic approaches.

Abstract P293: Effects of Diets That Vary in Fatty Acid Composition on Fecal Short-chain Fatty Acid Levels and Their Relationship With Circulating Lipids and Lipoproteins

Introduction: The short-chain fatty acids (SCFA) acetic acid, propionic acid, and butyric acid are microbial-produced metabolites that can influence host physiology through regulation of hepatic cholesterol metabolism. These biologically relevant gut metabolites may play a role in the hypocholesterolemic effects of select dietary components. The objective of this exploratory study was to determine the effects of diets that differ only in fatty acid composition on fecal SCFA levels and to assess their correlations with circulating lipids, lipoproteins, and apolipoproteins. Hypothesis: We assessed the hypothesis that dietary fat quality will differentially affect fecal SCFA and there will be significant associations between fecal SCFA levels and those of circulating total cholesterol, low-density lipoprotein-cholesterol (LDL-C), non-high-density lipoprotein-cholesterol (non-HDL-C), and apolipoprotein (apo) B. Methods: In a double-blind, randomized, three period crossover, controlled feeding clinical trial, participants with ≥2 metabolic syndrome criteria (n=20) were provided with a weight maintenance, controlled feeding base diet plus conventional canola oil, high-oleic acid canola oil (HOCO), or a control oil (control diet formulated to represent a Western diet fatty acid profile) for 6 weeks followed by washout periods of ≥4 weeks. The macronutrient profiles of the diets were: canola diet [17.5% monounsaturated fatty acid (MUFA), 9.2% polyunsaturated fatty acid (PUFA), 6.6% saturated fatty acid (SFA)], HOCO diet (19.1% MUFA, 7.0% PUFA, 6.4% SFA), and control diet (10.5% MUFA, 10.0% PUFA, 12.3% SFA). Fecal and blood samples were collected at study enrollment and at the end of each diet. Results: After 6 weeks, a trend toward a treatment effect on endpoint fecal propionic acid was observed ( P =0.09), with a trend toward a higher concentration following the control compared to the canola diet ( P =0.09). Acetic acid was increased from baseline following the control diet ( P =0.04). After the control diet only, fecal levels of propionic acid were positively correlated with blood levels of LDL-C, non-HDL-C, and apo B (r=0.52 to 0.64, P =0.003 to 0.02), with a trend for total cholesterol (r=0.39, P =0.10), and acetic acid was positively correlated with LDL-C and apo B levels (r=0.48 to 0.49, P =0.03 to 0.04), with a trend for non-HDL-C (r=0.44, P =0.06). No significant correlations between fecal SCFA and lipids and lipoproteins were observed after the two canola oil-based diets. Conclusions: In conclusion, these data suggest that the adverse effects of a contemporary Western diet fatty acid profile on circulating lipid and lipoprotein parameters compared to diets higher in unsaturated fat and lower in SFA may be mediated by gut-derived SCFA.