Major Short-chain Fatty Acids Research Articles

Date pomace polysaccharide: ultrasonic-assisted deep eutectic solvent extraction, physicochemical properties, biological activities, gut microbiota modulation, and rheological properties

BackgroundThis study utilized ultrasonication-assisted green extraction techniques to explore the physicochemical, rheological, biological, and prebiotic properties, alongside gut modulation abilities of novel polysaccharides extracted from date pomace. The extraction aimed at enhancing the utilization of date pomace, a by-product of date fruit processing, by investigating its potential as a functional food ingredient. The research focused on optimizing the extraction process, understanding the complex structure of the polysaccharides, and assessing their various health-related functionalities.ResultsThe ultrasonically extracted polysaccharides (UPS) were identified as a mixture of significant bioactive compounds including galacturonic acid, galactose, glucose, arabinose, and fructose, showcasing a high molecular weight of 537.7 kDa. The study found that UPS exhibited outstanding antioxidant activities, with scavenging abilities ranging from 59 to 82% at a concentration of 1000 mg/L. Additionally, UPS demonstrated potent inhibitory effects on α-amylase (83%), α-glucosidase (81%), and ACE-inhibition (45%), alongside strong antiproliferative activities against Caco-2 and MCF-7 cancer cell lines and broad-spectrum antimicrobial properties. Remarkably, UPS also enhanced the abundance of beneficial gut microbiota, including Actinobacteria, Firmicutes, and Proteobacteria, during in vitro fermentations and positively modulated gut metabolic pathways, promoting the production of major short-chain fatty acids. UPS had higher abundance in pathways related to cofactors, vitamins, electron carriers, and prosthetic groups biosynthesis compared to blank.ConclusionsThe findings affirm the potential of UPS extracted from date pomace as an innovative and promising functional food ingredient. Its high molecular weight, complex sugar composition, significant antioxidant, antimicrobial, antiproliferative activities, and prebiotic properties make it a valuable resource for promoting health and managing diseases. This study paves the way for further research on the bioavailability and physiological effects of UPS in vivo, highlighting the importance of sustainable utilization of agricultural by-products in developing functional foods that support human health.Graphical

Short-Chain Fatty Acids and Preeclampsia: A Scoping Review.

Preeclampsia (PE) is a pregnancy-associated hypertension disorder with high morbidity and mortality. Short-chain fatty acids (SCFAs)-molecules produced by gut microbes-have been associated with hypertension, yet their relation to PE remains uncertain. The aim was to review existing human studies that examined associations of the major SCFAs (acetate, propionate, butyrate) in pregnancy with PE development. Two reviewers independently searched online databases (EMBASE, PubMed, Web of Science, and Cochrane Database of Systematic Reviews) in January 2024 using the following terms: "short-chain fatty acids," "acetic acid," "butyric acid," "propionic acid," and "preeclampsia." The final set of included studies had to report associations of SCFAs with PE, be peer-reviewed, be written in English, and be conducted in humans. The abstracts of 907 studies were screened; 43 underwent full-text screening and 11 (1318 total participants, 352 with PE) were included in the final review. All studies used a case-control design. SCFAs were measured in a range of biospecimens (eg, serum, plasma, feces, placentas, and amniotic fluid) that were collected at distinct time points in pregnancy. All 7 studies that investigated butyrate found that it was lower in PE cases than in controls, with 6 of these showing statistical significance (P < .05). Five studies showed that acetate was significantly lower in individuals with PE compared with healthy individuals, while 1 study found that acetate was significantly higher in PE cases. One study reported significantly higher propionate among PE cases vs controls, while 2 studies reported significantly lower propionate levels in PE cases. The nuance in results for acetate and propionate may owe to reasons such as differences in distributions of population characteristics associated with SCFA level and PE or type of PE (early vs late). Current epidemiologic evidence, which derives only from case-control studies, suggests that SCFAs, particularly butyrate (protective), in pregnancy are related to the development of PE. Large-cohort studies are warranted to investigate the temporality and potential causality of these associations.

Quantifying fecal and plasma short-chain fatty acids in healthy Thai individuals

Short-chain fatty acids (SCFAs) are involved in important physiological processes such as gut health and immune response, and changes in SCFA levels can be indicative of disease. Despite the importance of SCFAs in human health and disease, reference values for fecal and plasma SCFA concentrations in healthy individuals are scarce. To address this gap in current knowledge, we developed a simple and reliable derivatization-free GC-TOFMS method for quantifying fecal and plasma SCFAs in healthy individuals. We targeted six linear- and seven branched-SCFAs, obtaining method recoveries of 73–88% and 83–134% in fecal and plasma matrices, respectively. The developed methods are simpler, faster, and more sensitive than previously published methods and are well suited for large-scale studies. Analysis of samples from 157 medically confirmed healthy individuals showed that the total SCFAs in the feces and plasma were 34.1 ± 15.3 µmol/g and 60.0 ± 45.9 µM, respectively. In fecal samples, acetic acid (Ace), propionic acid (Pro), and butanoic acid (But) were all significant, collectively accounting for 89% of the total SCFAs, whereas the only major SCFA in plasma samples was Ace, constituting of 93% of the total plasma SCFAs. There were no statistically significant differences in the total fecal and plasma SCFA concentrations between sexes or among age groups. The data revealed, however, a positive correlation for several nutrients, such as carbohydrate, fat, iron from vegetables, and water, to most of the targeted SCFAs. This is the first large-scale study to report SCFA reference intervals in the plasma and feces of healthy individuals, and thereby delivers valuable data for microbiome, metabolomics, and biomarker research.

Chronotropic and vasoactive properties of the gut bacterial short-chain fatty acids in larval zebrafish.

Short-chain fatty acids (SCFAs) produced by the gut bacteria have been associated with cardiovascular dysfunction in humans and rodents. However, studies exploring effects of SCFAs on cardiovascular parameters in the zebrafish, an increasingly popular model in cardiovascular research, remain limited. Here, we performed fecal bacterial 16S sequencing and gas chromatography/mass spectrometry (GC-MS) to determine the composition and abundance of gut microbiota and SCFAs in adult zebrafish. Following this, the acute effects of major SCFAs on heart rate and vascular tone were measured in anesthetized zebrafish larvae using fecal concentrations of butyrate, acetate, and propionate. Finally, we investigated if coincubation with butyrate may lessen the effects of angiotensin II (ANG II) and phenylephrine (PE) on vascular tone in anesthetized zebrafish larvae. We found that the abundance in Proteobacteria, Firmicutes, and Fusobacteria phyla in the adult zebrafish resembled those reported in rodents and humans. SCFA levels with highest concentration of acetate (27.43 µM), followed by butyrate (2.19 µM) and propionate (1.65 µM) were observed in the fecal samples of adult zebrafish. Immersion in butyrate and acetate produced a ∼20% decrease in heart rate (HR), respectively, with no observed effects of propionate. Butyrate alone also produced an ∼25% decrease in the cross-sectional width of the dorsal aorta (DA) at 60 min (*P < 0.05), suggesting compensatory vasoconstriction, with no effects of either acetate or propionate. In addition, butyrate significantly alleviated the decrease in DA cross-sectional width produced by both ANG II and PE. We demonstrate the potential for zebrafish in investigation of host-microbiota interactions in cardiovascular health.NEW & NOTEWORTHY We highlight the presence of a core gut microbiota and demonstrate in vivo short-chain fatty acid production in adult zebrafish. In addition, we show cardio-beneficial vasoactive and chronotropic properties of butyrate, and chronotropic properties of acetate in anesthetized zebrafish larvae.

Why does increased microbial fermentation in the human colon shift toward butyrate?

The microbial community of the human large intestine mainly ferments dietary fiber to short chain fatty acids (SCFAs), which are efficiently absorbed by the host. The three major SCFAs (acetate, propionate, and butyrate) have different fates within the body and different effects on health. A recent analysis of 10 human volunteer studies established that the proportions of these SCFA in fecal samples significantly shifted towards butyrate as the overall concentration of SCFA increased. Butyrate plays a key role in gut health and is preferentially utilized as an energy source by the colonic epithelium. Here we discuss possible mechanisms that underlie this 'butyrate shift'; these include the selection for butyrate-producing bacteria within the microbiota by certain types of fiber, and the possibility of additional butyrate formation from lactate and acetate by metabolite cross-feeding. However, a crucial factor appears to be the pH in the proximal colon, which decreases as the SCFA concentrations increase. A mildly acidic pH has been shown to have an important impact on microbial competition and on the stoichiometry of butyrate production. Understanding these complex interactions has been greatly aided by the refinement of theoretical models of the colonic microbiota that assume a small number (10) of microbial functional groups (MFGs).

Substituting ryegrass-based pasture with graded levels of forage rape in the diet of lambs reduced post-feeding variation in methane emissions

The temporal profile of methane (CH4) emissions from ruminants is affected by feed composition and forage type. This study aimed to 1) describe and compare the post-feeding pattern of CH4 emissions from lambs fed fresh ryegrass substituted with graded levels of forage rape, and 2) to evaluate the association between the magnitude of the variation in CH4 emission patterns and organic fermentation products quantified in pre- and- post- feeding rumen content samples. Methane emissions were measured at approximately 6 min intervals in respiration chambers from 70 lambs (n = 14 per treatment) fed ryegrass only (FR0) or as a proportion, 0.25 forage rape + 0.75 ryegrass (FR25), 0.50 forage rape + 0.50 ryegrass (FR50), 0.75 forage rape + 0.25 ryegrass (FR75), and forage rape only (FR100). The magnitude of the variability in CH4 emissions was defined as the ratio of maximum to minimum CH4 emissions in a 24 h period. This ratio was correlated (P < 0.05) with the proportions of major short chain fatty acids, and calculated hydrogen (H2) available per unit of glucose fermented (H2/GEF), quantified in rumen content samples collected pre- and- post- feeding. The CH4 emission profile after each feeding followed an asymmetrical positively skewed shape for FR0 to FR75, but not in lambs fed FR100. The lowest CH4 emission rates were observed before morning feeding which was followed by a CH4 peak within the 2 h after feeding, and then the CH4 emissions decreased until the next feeding. In FR100 lambs, the CH4 emission rate was, unexpectedly, relatively constant after feeding, without any clear CH4 peaks. The magnitude of the variability in the CH4 emission rate increased when the pH of rumen contents and H2/GEF measured in pre-feeding samples decreased. Including forage rape at 0.75, or greater proportion, in the diet of lambs drastically changed the CH4 emissions pattern, likely due to a continuous low pH in the rumen which is detrimental for methanogenesis. In conclusion, the daily variation in CH4 emissions decreased with increasing forage rape inclusion in the diet of sheep and this was associated with a decreasing acetate proportion in the rumen liquid.

Commensal Fecal Microbiota Profiles Associated with Initial Stages of Intestinal Mucosa Damage: A Pilot Study.

Progressive intestinal mucosal damage occurs over years prior to colorectal cancer (CRC) development. The endoscopic screening of polyps and histopathological examination are used clinically to determine the risk and progression of mucosal lesions. We analyzed fecal microbiota compositions using 16S rRNA gene-based metataxonomic analyses and the levels of short-chain fatty acids (SCFAs) using gas chromatography in volunteers undergoing colonoscopy and histopathological analyses to determine the microbiota shifts occurring at the early stages of intestinal mucosa alterations. The results were compared between diagnosis groups (nonpathological controls and polyps), between samples from individuals with hyperplastic polyps or conventional adenomas, and between grades of dysplasia in conventional adenomas. Some microbial taxa from the Bacillota and Euryarchaeota phyla were the most affected when comparing the diagnosis and histopathological groups. Deeper microbiota alterations were found in the conventional adenomas than in the hyperplastic polyps. The Ruminococcus torques group was enriched in both the hyperplastic polyps and conventional adenomas, whereas the family Eggerthellaceae was enriched only in the hyperplastic polyps. The abundance of Prevotellaceae, Oscillospiraceae, Methanobacteriaceae, Streptococcaceae, Christensenellaceae, Erysipelotrichaceae, and Clostridiaceae shifted in conventional adenomas depending on the grade of dysplasia, without affecting the major SCFAs. Our results suggest a reorganization of microbial consortia involved in gut fermentative processes.

New biochemical pathways for forming short-chain fatty acids during fermentation in rumen bacteria

Short-chain fatty acids (SCFA) are essential to cattle as a source of energy and for other roles in metabolism. These molecules are formed during fermentation by microbes in the rumen, but even after decades of study, the biochemical pathways responsible for forming them are not always clear. Here we review recent advances in this area and their importance for improving animal productivity. Studies of bacterial genomes have pointed to unusual biochemical pathways in rumen organisms. One study found that 8% of rumen organisms forming acetate, a major SCFA, had genes for a pathway previously unknown in bacteria. The existence of this pathway was subsequently confirmed biochemically in propionibacteria. The pathway was shown to involve 2 enzymes that convert acetyl-coenzyme A to acetate. Similar studies have revealed new enzymatic steps for forming propionate and butyrate, other major SCFA. These new steps and pathways are significant for controlling fermentation. With more precise control over SCFA, cows can be fed more precisely and potentially reach higher productivity.

Combination of Selenite and Butyrate Enhances Efficacy Against Colon Cancer by Targeting ASCT2-Mediated Amino Acid Metabolism.

Drug combination is considered to be an effective approach to improve the efficacy of cancer therapy and chemoprevention. Selenite, a representative of inorganic form of selenium, and butyrate, a major short-chain fatty acid, are two well-documented colon cancer dietary chemopreventive agents with distinct molecular mechanisms. We hypothesized that combination of selenite and butyrate might produce improved outcome against colon cancer. This hypothesis was tested using both HCT116 human colon cancer cells and its xenograft mouse model in the present study. The in vitro study showed a synergistically inhibitory effect on HCT116 colon cancer cells but not on NCM460 normal human colon mucosal epithelial cells. Consistent with the in vitro study, results of the xenograft mouse model further demonstrated that combination of selenite and butyrate led to improved efficacy in comparison with each agent alone. Mechanistically, the induction of alanine-serine-cysteine transporter 2 (ASCT2) by selenite repressed its inhibitory effect on colon cancer cells, which was reversed by its co-treatment with butyrate. The findings of the present study denote the likely potential for developing selenite/butyrate combination remedy to combat against colon cancer.

Butyrate acts as a G-protein-coupled receptor ligand that prevents high glucose-induced amyloidogenesis in N2a cells through the protein kinase B/glycogen synthase kinase-3β pathway.

Butyrate acts as a G-protein-coupled receptor ligand that prevents high glucose-induced amyloidogenesis in N2a cells through the protein kinase B/glycogen synthase kinase-3β pathway.

A High-Fat, High-Cholesterol Diet Promotes Intestinal Inflammation by Exacerbating Gut Microbiome Dysbiosis and Bile Acid Disorders in Cholecystectomy.

Patients with post-cholecystectomy (PC) often experience adverse gastrointestinal conditions, such as PC syndrome, colorectal cancer (CRC), and non-alcoholic fatty liver disease (NAFLD), that accumulate over time. An epidemiological survey further revealed that the risk of cholecystectomy is associated with high-fat and high-cholesterol (HFHC) dietary intake. Mounting evidence suggests that cholecystectomy is associated with disrupted gut microbial homeostasis and dysregulated bile acids (BAs) metabolism. However, the effect of an HFHC diet on gastrointestinal complications after cholecystectomy has not been elucidated. Here, we aimed to investigate the effect of an HFHC diet after cholecystectomy on the gut microbiota-BA metabolic axis and elucidate the association between this alteration and the development of intestinal inflammation. In this study, a mice cholecystectomy model was established, and the levels of IL-Iβ, TNF-α, and IL-6 in the colon were increased in mice fed an HFHC diet for 6 weeks. Analysis of fecal BA metabolism showed that an HFHC diet after cholecystectomy altered the rhythm of the BA metabolism by upregulating liver CPY7A1, CYP8B1, and BSEP and ileal ASBT mRNA expression levels, resulting in increased fecal BA levels. In addition, feeding an HFHC diet after cholecystectomy caused a significant dysbiosis of the gut microbiota, which was characterized by the enrichment of the metabolic microbiota involved in BAs; the abundance of pro-inflammatory gut microbiota and related pro-inflammatory metabolite levels was also significantly higher. In contrast, the abundance of major short-chain fatty acid (SCFA)-producing bacteria significantly decreased. Overall, our study suggests that an HFHC diet after cholecystectomy promotes intestinal inflammation by exacerbating the gut microbiome and BA metabolism dysbiosis in cholecystectomy. Our study also provides useful insights into the maintenance of intestinal health after cholecystectomy through dietary or probiotic intervention strategies.

Development and validation of derivatization-based LC-MS/MS method for quantification of short-chain fatty acids in human, rat, and mouse plasma

Short-chain fatty acids (SCFAs), the end products of gut microbial fermentation of dietary fibers and non-digestible polysaccharides, act as a link between the microbiome, immune system, and inflammatory processes. The importance of accurately quantifying SCFAs in plasma has recently emerged to understand their biological role. In this work, a sensitive and reproducible LC-MS/MS method is reported for SCFAs quantification in three different matrices such as human, rat and mouse plasma via derivatization, using as derivatizing agent O-benzylhydroxylamine (O-BHA), coupled with liquid-liquid extraction. First, the instrumental parameters of the mass spectrometer and then the chromatographic conditions were optimized using previously SCFAs derivatives synthetized and used as standards. After that, the best conditions for derivatization and extraction from plasma were studied and a series of determinations were performed on human, rat, and mouse plasma aliquots to validate the overall method (derivatization, extraction, and LC-MS/MS determination). The method showed good performance in terms of recovery (> 80%), precision (RSD <14%), accuracy (RE < ± 10%) and sensitivity (LOQ of 0.01 µM for acetic, butyric, propionic and isobutyric acid) in all plasma samples. The method thus developed and validated was applied to the quantification of major SCFAs in adult and aged mice, germ-free mice and in germ-free recipient mice subjected to fecal transplant from adult and aged donors. Results highlighted how plasma concentrations of SCFAs are correlated with age further highlighting the importance of developing a method that is reliable for the quantification of SCFAs to study their biological role.

Microbial metabolite n-butyrate upregulates intestinal claudin-23 expression through SP1 and AMPK pathways in mouse colon and human intestinal Caco-2 cells

AimsRegulation of the intestinal barrier is closely related to intestinal microbial metabolism. This study investigated the role of intestinal microflora in the regulation of the tight junction (TJ) barrier in epithelial cells, focusing on the microbial metabolite n-butyrate, a major short-chain fatty acid, using mice and human intestinal Caco-2 cells. Materials and methodsWhole transcriptome analysis with RNA sequencing and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were performed in the colon of germ-free (GF) and specific pathogen-free (SPF) mice. Claudin-23 expression was examined by qRT-PCR, immunoblotting, and immunofluorescence in Caco-2 cells treated with n-butyrate. Luciferase reporter assay was performed to examine the effect of n-butyrate on claudin-23 transcriptional activity. The siRNA targeting the transcription factor SP1 and pharmacological inhibitor of AMPK were used in combination. TJ permeability was examined in canine kidney MDCKII cells stably expressing human claudin-23. Key findingsCldn23 mRNA expression was downregulated in the colon of GF mice (0.6-fold) compared to that in SPF mice. n-Butyrate upregulated claudin-23 mRNA (1.7-fold) and protein (2.1-fold) expression as well as increased the transcriptional activity (15-fold) of CLDN23 in Caco-2 cells. The n-butyrate-mediated increase in claudin-23 expression and transcriptional activity was reduced by inhibition of SP1 and AMPK. Exogenously expressed human claudin-23 in MDCKII cells did not affect TJ permeability to ions and macromolecules. Significancen-Butyrate regulates intestinal claudin-23 expression through the SP1 and AMPK pathways. This mechanism may be involved in the beneficial effects of n-butyrate-mediated intestinal homeostasis.

Multi-Omics Reveals the Impact of Exogenous Short-Chain Fatty Acid Infusion on Rumen Homeostasis: Insights into Crosstalk between the Microbiome and the Epithelium in a Goat Model.

Emerging data have underscored the significance of exogenous supplementation of butyrate in the regulation of rumen development and homeostasis. However, the effects of other short-chain fatty acids (SCFAs), such as acetate or propionate, has received comparatively less attention, and the consequences of extensive exogenous SCFA infusion remain largely unknown. In our study, we conducted a comprehensive investigation by infusion of three SCFAs to examine their respective roles in regulating the rumen microbiome, metabolism, and epithelium homeostasis. Data demonstrated that the infusion of sodium acetate (SA) increased rumen index while also promoting SCFA production and absorption through the upregulation of SCFA synthetic enzymes and the mRNA expression of SLC9A1 gene. Moreover, both SA and sodium propionate infusion resulted in an enhanced total antioxidant capacity, an increased concentration of occludin, and higher abundances of specific rumen bacteria, such as "Candidatus Saccharimonas," Christensenellaceae R-7, Butyrivibrio, Rikenellaceae RC9 gut, and Alloprevotella. In addition, sodium butyrate (SB) infusion exhibited positive effects by increasing the width of rumen papilla and the thickness of the stratum basale. SB infusion further enhanced antioxidant capacity and barrier function facilitated by cross talk with Monoglobus and Incertae Sedis. Furthermore, metabolome and transcriptome data revealed distinct metabolic patterns in rumen contents and epithelium, with a particular impact on amino acid and fatty acid metabolism processes. In conclusion, our data provided novel insights into the regulator effects of extensive infusion of the three major SCFAs on rumen fermentation patterns, antioxidant capacity, rumen barrier function, and rumen papilla development, all achieved without inducing rumen epithelial inflammation. IMPORTANCE The consequences of massive exogenous supplementation of SCFAs on rumen microbial fermentation and rumen epithelium health remain an area that requires further exploration. In our study, we sought to investigate the specific impact of administering high doses of exogenous acetate, propionate, and butyrate on rumen homeostasis, with a particular focus on understanding the interaction between the rumen microbiome and epithelium. Importantly, our findings indicated that the massive infusion of these SCFAs did not induce rumen inflammation. Instead, we observed enhancements in antioxidant capacity, strengthening of rumen barrier function, and promotion of rumen papilla development, which were facilitated through interactions with specific rumen bacteria. By addressing existing knowledge gaps and offering critical insights into the regulation of rumen health through SCFA supplementation, our study holds significant implications for enhancing the well-being and productivity of ruminant animals.

Effect of a probiotic formula on gastrointestinal health, immune responses and metabolic health in adults with functional constipation or functional diarrhea.

Our aim was to determine the efficacy of four-week probiotic supplementation on gastrointestinal health. The secondary objectives were to assess probiotic effects on immune reaction, as well as weight control and metabolic health. We conducted two randomized sub-trials, respectively, among subjects who were diagnosed with functional constipation (FC) or functional diarrhea (FDr) according to the Rome IV criteria. In each sub-trial, 70 eligible Chinese adults were randomized to receive a multi-strain probiotic combination or a placebo. Gastrointestinal symptoms, defecation habits, stool characteristics, blood and fecal biochemistry markers, anthropometrics measures, stress-associated responses, and intestinal flora changes were assessed at baseline and after probiotics intervention. Four weeks of probiotic supplementation reduced overall gastrointestinal symptoms scores in FC participants (p < 0.0001). Their mean weekly stool frequency increased from 3.3 times to 6.2 times; immune response and inflammation markers improved with increases in serum IgA, IFN-γ and fecal sIgA, and decrease in hsCRP; most components of lipid profile were significantly ameliorated, with increases in HDL-C and reductions in TC and TG; body weight, body mass index and basal metabolic rate decreased following probiotics consumption. For FDr participants, probiotics consumption markedly reduced overall gastrointestinal symptom scores (p < 0.0001); decreased stool frequency by 3 times per week; increased IgA, IFN-γ, sIgA concentrations, while lowered hsCRP and IL-4 levels. Both FC and FDr participants had improvement in the scores of defecation habits, anxiety or depression, and perceived stress. Probiotics supplementation promoted the production of all three major short-chain fatty acids. No changes were observed in LDL-C, IgG, IgM, IL-8, IL-10 and motilin. Supplementation with the probiotic formula over a four-week period could help relieving gastrointestinal symptoms, improving satisfaction with defecation habits, emotional state and immune response, and ameliorating dysbacteriosis in participants with FC or FDr. It also had beneficial effects on lipid metabolism and weight control for FC participants.

Lactobacillus rhamnosus KBL2290 Ameliorates Gut Inflammation in a Mouse Model of Dextran Sulfate Sodium-Induced Colitis.

Ulcerative colitis, a major form of inflammatory bowel disease (IBD) associated with chronic colonic inflammation, may be induced via overreactive innate and adaptive immune responses. Restoration of gut microbiota abundance and diversity is important to control the pathogenesis. Lactobacillus spp., well-known probiotics, ameliorate IBD symptoms via various mechanisms, including modulation of cytokine production, restoration of gut tight junction activity and normal mucosal thickness, and alterations in the gut microbiota. Here, we studied the effects of oral administration of Lactobacillus rhamnosus (L. rhamnosus) KBL2290 from the feces of a healthy Korean individual to mice with DSS-induced colitis. Compared to the dextran sulfate sodium (DSS) + phosphate-buffered saline control group, the DSS + L. rhamnosus KBL2290 group evidenced significant improvements in colitis symptoms, including restoration of body weight and colon length, and decreases in the disease activity and histological scores, particularly reduced levels of pro-inflammatory cytokines and an elevated level of anti-inflammatory interleukin-10. Lactobacillus rhamnosus KBL2290 modulated the levels of mRNAs encoding chemokines and markers of inflammation; increased regulatory T cell numbers; and restored tight junction activity in the mouse colon. The relative abundances of genera Akkermansia, Lactococcus, Bilophila, and Prevotella increased significantly, as did the levels of butyrate and propionate (the major short-chain fatty acids). Therefore, oral L. rhamnosus KBL2290 may be a useful novel probiotic.

Association of Gut Lachnospiraceae and Chronic Spontaneous Urticaria.

(1) Background: Chronic spontaneous urticaria (CSU) has been linked to the dysbiosis of the gut microbiota. Furthermore, various studies have highlighted the anti-inflammatory properties of short-chain fatty acids (SCFAs), whose production is primarily regulated by the gut microbiota. However, only a few studies have investigated the role of major SCFA producers, such as Lachnospiraceae, in skin inflammatory diseases. (2) Goal: This study aimed to compare the abundance of Lachnospiraceae between CSU patients and healthy controls (HCs). (3) Material and methods: In this case-control study, 16S rRNA sequencing was performed to compare the composition of the gut microbiome between 22 CSU patients and 23 HCs. (4) Results: Beta-diversity revealed significant clustering (p < 0.05) between the CSU patients and HCs. Alpha diversity in the CSU group was significantly decreased according to the Evenness index (p < 0.05). The linear discriminant analysis effect size (LEfSe) identified the significant depletion of the Lachnospiraceae family in CSU patients. (5) Conclusion: Our study revealed the dysbiosis of the gut microbiota in CSU patients, including decreased levels of Lachnospiraceae members, responsible for SCFA production, suggesting that SCFAs may contribute to immune dysfunction in the pathogenesis of CSU. We speculate that the modulation of SCFAs could serve as a prospective additional option in CSU treatment.

Asteraceae Seeds as Alternative Ingredients in a Fibre-Rich Diet: Protein Quality and Metabolic Effects in Rats.

We verified whether milk thistle seeds and pot marigold seeds provided valuable components for a fibre-rich diet and how their addition affected body composition, nitrogen balance and lipid metabolism in rats. Growing rats were fed a control diet (5% fibre) or three fibre-rich diets (24% fibre), which contained cellulose as the sole source of fibre (24%; positive control), milk thistle seeds (32%) or pot marigold seeds (39%). All diets were balanced in macronutrients, including total protein content (9%), which was half of the amount recommended for rats to maximise protein absorption and utilisation, and the ratio of plant protein to animal protein (approx. 1:1). After 4 weeks, dietary pot marigold seeds reduced body weight gain, which translated into lower gains of body fat and lean mass in rats (all at p ≤ 0.05). Protein digestibility differed among individual fibre-rich diets (p ≤ 0.05), with the lowest result having been recorded for dietary pot marigold seeds (73%), followed by dietary milk thistle seeds (78%), and the highest result having been recorded for dietary soybean protein isolate (control protein source, 89%). Nitrogen retention was higher with dietary soybean protein isolate (53%) and dietary milk thistle seeds (47%) than with dietary pot marigold seeds (38%) (p ≤ 0.05). In the caecal digesta, the concentrations of the major short-chain fatty acids were almost or >2-fold higher after dietary milk thistle seeds and pot marigold seeds than after the positive control diet (all at p ≤ 0.05). Dietary pot marigold seeds enlarged the liver and increased the plasma activities of liver enzymes but reduced hepatic lipid contents (all at p ≤ 0.05). Certain Asteraceae seeds provide components of varied nutritional quality, with milk thistle seeds being a relatively good source of protein and both types of seeds being a source of fermentable fibre. Pot marigold seeds have potential anti-obesogenic effects, but with the risk of damaging internal organs.

Na+-dependent intestinal glucose absorption mechanisms and its luminal Na+ homeostasis across metamorphosis from tadpoles to frogs.

The abrupt morphological changes of the intestine during metamorphosis have been detailed in frogs. The features of intestinal metamorphosis are shortening of the intestine and remodeling of the intestinal epithelium. It is believed that the purpose of the morphological changes of the intestine is adaptation from aquatic herbivorous to carnivorous life. However, little is known about the physiological importance of these morphological changes. To elucidate the functional changes during metamorphosis, we measured luminal Na+ concentrations and Na+-dependent glucose uptake in tadpoles and adult African clawed frogs Xenopus laevis. The small intestine was isolated and divided into four segments in length, the luminal contents collected for analysis of ion concentration by ion chromatography. Phlorizin-sensitive glucose-induced short-circuit current (ΔIsc) was measured in intestinal preparations mounted in Ussing chambers. Although dietary sodium intake was extremely low in tadpoles, luminal Na+ concentration gradually increased along the proximal to the middle part of the intestine (>70 mM), and this Na+ concentration was comparable with that of carnivorous adult frogs. The increment of glucose-induced ΔIsc was observed in tadpole intestine. We also measured the ΔIsc induced by acetic acid, which is the major short-chain fatty acid produced by fermentation. The expression levels of mRNA for Na+-dependent glucose transporter 1 and tight junction protein claudin-15 in each intestinal segment was measured. These results suggest that luminal Na+ homeostasis is important and luminal Na+ is kept at a high concentration for Na+-dependent nutrient absorption mechanisms.

Propionate regulates tight junction barrier by increasing endothelial-cell selective adhesion molecule in human intestinal Caco-2 cells

Regulation of the intestinal barrier is closely associated with intestinal microbial metabolism. This study investigated the role of propionate, a major short-chain fatty acid produced by intestinal microorganisms, in the regulation of the tight junction (TJ) barrier in human intestinal Caco-2 cells. Propionate strengthened TJ barrier integrity, as indicated by decreased permeability to macromolecules and increased transepithelial electrical resistance in Caco-2 cells. DNA microarray analysis revealed that propionate upregulated endothelial cell-selective adhesion molecule (ESAM), a TJ-associated protein, without any increase in other TJ proteins. The upregulation of ESAM was confirmed using quantitative reverse transcription-PCR, immunoblotting, and immunofluorescence analyses. Luciferase promoter analysis demonstrated that propionate induced the transcriptional activation of ESAM. The effects of propionate were sensitive to nilotinib inhibition of NR2C2. Overexpression of human ESAM (hESAM) in canine kidney epithelial MDCK-II cells lowered the permeability to macromolecules in a manner similar to that of propionate-treated Caco-2 cells. hESAM overexpression facilitated calcium-induced assembly of the TJ complex in MDCK-II cells. Taken together, propionate strengthened the intestinal TJ barrier by increasing ESAM levels in Caco-2 cells.