Intestinal Metabolism Research Articles

The intestinal-level metabolic benefits of green tea catechins: Mechanistic insights from pre-clinical and clinical studies

BackgroundThe intestinal-level host-microbiota interaction has been implicated in the pathogenesis of chronic diseases. The current review is intended to provide a comprehensive insight into deciphering whether intestinal-level bioactivities mediate the overall metabolic health benefits of green tea catechins. PurposeWe have comprehensively discussed pre-clinical and clinical evidences of intestinal-level changes in metabolism, microbiota, and metabolome due to catechin-rich green tea treatments, ultimately limiting metabolic diseases. Exclusive emphasis has been given to purified catechins and green tea, and discussions on extraintestinal mechanisms of metabolic health benefits were avoided. MethodsA literature search for relevant pre-clinical and clinical studies was performed in various online databases (e.g., PubMed) using specific keywords (e.g., catechin, intestine, microbiota). Out of all the referred literature, ∼15% belonged to 2021-2023, ∼51% were from 2011-2020, and ∼32% from 2000-2010. ResultThe metabolic health benefits of green tea catechins are indeed influenced by the intestinal-level bioactivities, including reduction of mucosal inflammation and oxidative stress, attenuation of gut barrier dysfunction, decrease in intestinal lipid absorption and metabolism, favorable modulation of mucosal nuclear receptor signaling, alterations of the luminal global metabolome, and mitigation of the gut dysbiosis. The results from the recent clinical studies support the pre-clinical evidences. The challenges and pitfalls of the currently available knowledge on catechin bioactivities have been discussed, and constructive directions to harness the translational benefits of green tea through future interventions have been provided. ConclusionThe metabolism, metabolome, and microbiota at the intestinal epithelia play critical roles in catechin metabolism, pharmacokinetics, bioavailability, and bioactivities. Especially the reciprocal interaction between the catechins and the gut microbiota dictates the metabolic benefits of catechins.

High-Altitude Hypoxia Induces Excessive Erythrocytosis in Mice via Upregulation of the Intestinal HIF2a/Iron-Metabolism Pathway.

Excessive erythrocytosis (EE) is a preclinical form of chronic mountain sickness (CMS). The dysregulation of iron metabolism in high-altitude hypoxia may induce EE. The intestinal hypoxia-inducible factor 2 alpha (HIF2a) regulates the genes involved in iron metabolism. Considering these findings, we aimed to investigate the function and mechanism of intestinal HIF2α and the iron metabolism pathway in high-altitude EE mice. C57BL/6J mice were randomized into four groups: the low-altitude group, the high-altitude group, the high-altitude + HIF2α inhibitor group, and the high-altitude + vehicle group. In-vitro experiments were performed using the human intestinal cell line HCT116 cultured under hypoxic conditions for 24 h. Results showed that high-altitude hypoxia significantly increased the expression of intestinal HIF2α and iron metabolism-related genes, including Dmt1, Dcytb, Fpn, Tfrc, and Fth in EE mice. Genetic blockade of the intestinal HIF2α-iron metabolism pathway decreased iron availability in HCT116 cells during hypoxia. The HIF2α inhibitor PT2385 suppressed intestinal HIF2α expression, decreased iron hypermetabolism, and reduced excessive erythrocytosis in mice. These data support the hypothesis that exposure to high-altitude hypoxia can lead to iron hypermetabolism by activating intestinal HIF2α transcriptional regulation, and reduced iron availability improves EE by inhibiting intestinal HIF2α signaling.

Formulation and Evaluation of Mixed Micelles Containing Quercetin for Inhibiting Intestinal Metabolism of Atorvastatin

Atorvastatin is a poorly bioavailable drug due to fast-pass metabolism. The objective of the study was to prepare quercetin-containing mixed micelles for inhibiting intestinal metabolism of Atorvastatin. Mixed micelles of atorvastatin were prepared using the film hydration method and optimized the formulations were based on different ratios of poloxamer 188 and SDC. The drug permeation and permeability coefficients of mixed micelles were calculated from ex vivo study using goat intestine. To the optimized formulation (F7), quercetin was added to improve the permeability of Atorvastatin. The vesicle size, % entrapment efficiency, and % in vitro drug release of optimized formulation (F7) were found 273.11 nm, 91.34 % and 72.14 %, respectively. The ex vivo results of Atorvastatin with quercetin (25 mg) showed two times more permeation (flux = 2.69 µg/cm2h) and Atorvastatin mixed micelles with quercetin (25 mg) showed three times (flux = 4.33 µg/cm2h ) compared to Atorvastatin without quercetin (flux = 1.34 µg/cm2h). The improvement of Atorvastatin permeation in the form of mixed micelles may be due to the blockage of the p glycoprotein efflux pump in the presence of quercetin. Histopathology study indicated that the formulation changed the microenvironment of tissue when using mixed micelles compared to no significant changes that occurred during control tissue. Based on the obtained results, we can conclude that the mixed micelles containing Atorvastatin enhanced the permeability effect in the presence of quercetin compared to the plain formulation without quercetin.

Lactiplantibacillus plantarum GL001 alleviates jejunal oxidative damage induced by intestinal ischemia-reperfusion injury by influencing jejunal tissue metabolism through the improvement of jejunal microbial composition

Intestinal ischemia-reperfusion (IIR) injury is associated with inflammation and oxidative stress, yet its precise mechanisms remain not fully understood. IIR injury is closely linked to the gut microbiota and its metabolites. The anti-inflammatory and antioxidant effects of Lactiplantibacillus plantarum are specific to IIR. In our study, we conducted a 30-day pre-treatment of SD rats with both a standard strain of Lactiplantibacillus plantarum and Lactiplantibacillus plantarum GL001. After a 7-day cessation of treatment, we induced an IIR injury model to investigate the mechanisms by which Lactiplantibacillus plantarum alleviates IIR damage. The results demonstrate that Lactiplantibacillus plantarum effectively mitigates the inflammatory and oxidative stress damage induced by IIR. Lactiplantibacillus plantarum GL001 can improve the gut microbiota by reducing the abundance of harmful bacteria and increasing the abundance of beneficial bacteria. In IIR intestinal tissue, the levels of secondary bile acids are elevated. The content of the bacterial metabolite Calcimycin increases. Annotations of metabolic pathways suggest that Lactiplantibacillus plantarum GL001 can alleviate IIR damage by modulating calcium-phosphorus homeostasis through the regulation of parathyroid hormone synthesis, secretion, and action. Microbiota-metabolite correlation analysis reveals a significant negative correlation between calcimycin and Lactonacillus and a significant positive correlation between calcimycin and Shigella. There is also a significant positive correlation between calcimycin and secondary bile acids. Lactiplantibacillus plantarum GL001 can alleviate oxidative damage induced by IIR through improvements in gut microbiota and intestinal tissue metabolism.

Shengjiang Xiexin decoction mitigates murine Clostridium difficile infection through modulation of the gut microbiota and bile acid metabolism

Ethnopharmacological relevanceThe overuse of antibiotics has resulted in Clostridium difficile infection (CDI) as a significant global public health concern. Studies have shown that imbalances in gut microbiota and metabolism play a vital role in the onset of CDI. Shengjiang Xiexin decoction (SJT), a traditional Chinese medicinal formula widely employed in the treatment of gastrointestinal ailments, demonstrates effectiveness in addressing murine CDI. However, the precise mechanistic role of SJT in CDI treatment remains uncertain, particularly regarding its impact on gut microbiota and intestinal metabolism. Thus, further investigation is imperative to shed light on these mechanisms. Aim of the studyThis study aims to thoroughly investigate the therapeutic potential of SJT in the treatment of CDI, while also examining its impact on the intricate interplay between gut microbiota and bile acid metabolism. By employing a mouse model, we aspire to uncover novel insights that could pave the way for the development of more effective strategies in combating CDI. Materials and methodsWe developed a mouse model for CDI and assessed SJT's potential as a therapeutic agent through pharmacological analyses. Our study employed high-throughput sequencing of 16S rRNA to identify changes in gut microbiota composition and untargeted metabolomics analysis to evaluate SJT's intervention on intestinal metabolism. We also conducted targeted analysis of bile acid metabolism to examine the specific effects of SJT. Finally, the growth-inhibitory effect of SJT on C. difficile was confirmed through ex vivo cultivation of the pathogen using cecal contents, supporting its potential role in treating CDI by modulating gut microbiota and bile acid metabolism. ResultsIn pharmacological studies, SJT was found to effectively reduce the levels of A&B toxins and alleviate colonic inflammation in CDI mice. Mechanistically, SJT demonstrated a mild increase in the abundance and diversity of the gut microbiota. However, its most significant impact was observed in the substantial improvement of the structural composition of the gut microbiota. Specifically, SJT decreased the abundance of gut Polymorphs and Firmicutes while restoring the proportions of family Trichophyton and Bacteroides_S24-7 spp (P < 0.001). Moreover, SJT not only decreased the levels of primary bile acids but also elevated the levels of secondary bile acids. Notably, it enhanced the conversion of taurocholic acid (TCA) to deoxycholic acid (DCA), leading to a balanced bile acid metabolism. Finally, cecal contents of SJT-treated mice showed a significant reduction in the growth of C. difficile, underscoring the therapeutic potential of SJT via modulation of gut microbiota and bile acid metabolism. ConclusionSJT demonstrates remarkable efficacy in treating CDI in mice by not only effectively combating the infection but also restoring the intricate balance of gut microbiota and bile acid metabolism. Furthermore, promising indications suggest that SJT may have the potential to prevent CDI recurrence. These findings underscore the comprehensive therapeutic value of SJT in managing CDI. Moving forward, we plan to transition from the laboratory to clinical settings to conduct further studies, validating our conclusions on SJT's efficacy.

Integration of Deep Learning and Sequential Metabolism to Rapidly Screen Dipeptidyl Peptidase (DPP)-IV Inhibitors from Gardenia jasminoides Ellis.

Traditional Chinese medicine (TCM) possesses unique advantages in the management of blood glucose and lipids. However, there is still a significant gap in the exploration of its pharmacologically active components. Integrated strategies encompassing deep-learning prediction models and active validation based on absorbable ingredients can greatly improve the identification rate and screening efficiency in TCM. In this study, the affinity prediction of 11,549 compounds from the traditional Chinese medicine system's pharmacology database (TCMSP) with dipeptidyl peptidase-IV (DPP-IV) based on a deep-learning model was firstly conducted. With the results, Gardenia jasminoides Ellis (GJE), a food medicine with homologous properties, was selected as a model drug. The absorbed components of GJE were subsequently identified through in vivo intestinal perfusion and oral administration. As a result, a total of 38 prototypical absorbed components of GJE were identified. These components were analyzed to determine their absorption patterns after intestinal, hepatic, and systemic metabolism. Virtual docking and DPP-IV enzyme activity experiments were further conducted to validate the inhibitory effects and potential binding sites of the common constituents of deep learning and sequential metabolism. The results showed a significant DPP-IV inhibitory activity (IC50 53 ± 0.63 μg/mL) of the iridoid glycosides' potent fractions, which is a novel finding. Genipin 1-gentiobioside was screened as a promising new DPP-IV inhibitor in GJE. These findings highlight the potential of this innovative approach for the rapid screening of active ingredients in TCM and provide insights into the molecular mechanisms underlying the anti-diabetic activity of GJE.

Comparison of Berberine Bioavailability between Oral and Rectal Administrations in Rats.

The oral bioavailability of berberine is quite low due to extensive first-pass metabolism. To increase the bioavailability of berberine (BBR), the efficacy of rectal administration that can avoid intestinal and hepatic first-pass metabolism partly was evaluated using BBR sulfate in rats. BBR sulfate was administered intravenously (1 mg/kg as BBR), orally (10 mg/kg as BBR) and rectally (1, 3, or 10 mg/kg as BBR) using Witepsol® H15 suppository base to evaluate bioavailability in rats. Concentrations of BBR in plasma were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). When BBR sulfate was administered orally, the average oral bioavailability was 0.26%. When BBR sulfate was administered rectally, the average bioavailabilities were 17.0% at 1 mg/kg, 24.3% at 3 mg/kg, and 12.3% at 10 mg/kg as BBR, respectively. Thus, rectal administration of BBR sulfate greatly increased the bioavailability of BBR as compared with oral administration, which would also increase the pharmacological activities of BBR in vivo.

Effects of Branched-Chain Fatty Acids Derived from Yak Ghee on Lipid Metabolism and the Gut Microbiota in Normal-Fat Diet-Fed Mice.

Branched-chain fatty acids (BCFAs) are natural components with a variety of biological activities. However, the regulation of lipid metabolism by BCFAs is unknown. It was dedicated to examining the impacts of BCFAs inferred from yak ghee on the expression of qualities related to lipid metabolism, natural pathways, and intestinal microbiota in mice. The treatment group (purified BCFAs from yak ghee) exhibited a decrease in cholesterol levels; a decrease in HMGCR levels; downregulation of FADS1, FADS2, ACC-α, FAS, GAPT4, GPAM, ACSL1, THRSP, A-FABP, and PPARα gene expression; and upregulation of SCD1, ACSS1, FABP1, CPT1, and DGAT-1 gene expression. Gut microbiota 16S rDNA sequencing analysis showed that the treatment group improved the gut microbiota by increasing the relative abundances and increasing the short-chain fatty acid levels produced by the genera Akkermansia, Clostridium, Lachnospiraceae, Lactobacillus, Anaerotaenia, and Prevotella. After adding BCFAs to cultured breast cancer cells, pathways that were downregulated were found to be related to fatty acid degradation and fatty acid metabolism, while 20 other pathways were upregulated. Our results suggest that BCFAs reduce body fat in mice by modulating intestinal flora and lipid metabolism and modulating fatty acid metabolism in breast cancer cells.

The gut–Snhg9 interplay as a new path to metabolic health

Parsing the intricate interplay between gut microbiota, gene modulation, and host metabolism remains challenging. Wang et al. employed diverse methods to uncover how the gut microbiota reshapes intestinal lipid metabolism through the lncRNA Snhg9, underscoring the value of systems biology approaches in dissecting host–microbiome relationships involved in metabolic disorders.

Intestinal flora, intestinal metabolism, and intestinal immunity changes in complete Freud's adjuvant-rheumatoid arthritis C57BL/6 mice

Rheumatoid arthritis (RA) is an inflammatory-mediated autoimmune disease characterized by persistent joint enlargement, synovial cartilage damage, and inflammatory infiltrates. Although the pathogenesis and treatment of RA are still currently insufficient, the importance of the intestine flora, metabolism and immunity for RA has been gradually recognized, and many intestine regulatory strategies have been used to treat RA. However, the relationship between RA and intestine flora, metabolism and immunity has not been fully expounded. In this study, Complete Freund's Adjuvant (CFA) was used to establish RA model, CyTOF technology was used to study the changes of intestinal immune cell types, 16S rRNA technology was used to analyze the differences of intestinal flora, and LC-MS technology was used to explain the effects of metabolites produced by the changed intestinal flora on RA. Moreover, we systematically explored how the imbalance of intestinal flora changed the intestinal immune status through its metabolites in RA mice. Our results showed that the intestinal flora of RA mice changed significantly, and the bacteria producing short-chain fatty acids (SCFAs), indole classes and secondary bile acids were significantly reduced. The abundance of SCFAs, indole classes and secondary bile acids in the intestine were significantly decreased. The balance of immune cells in the intestine of RA mice was significantly disrupted, with an overall decrease in immune cells. This work reveals the possible relationship between intestinal flora, metabolism and immunity and RA in mice, which will provide new therapeutic strategies for RA.

Molecular mechanisms regulating uric acid metabolism in the human intestine, systematic literature review

This review presents recent data on direct and indirect pathogenetic relationships between metabolism of purine compounds and biochemical processes in cells of the digestive system. A comprehensive analysis of available modern publications for the period from 2000 to 2022 in the Scopus, PubMed, eLIIBRARY, and Google Scholar databases was performed. The hypothesis linking the pathogenesis of hyperuricemia to “renal overload” suggests that the disease may develop due to impaired renal excretion with insufficient excretion of uric acid (UA) via the intestine. Some of the UA transport systems work actively in hepatocytes and enterocytes, which determines their formation and excretion. UA transporter proteins are divided into two categories: urate reabsorption transporters and urate excretion transporters; their expression is regulated by transcription factors, hormones, and metabolites of the intestinal microflora. The influence of intestinal microbiota on UA metabolism is associated with its involvement in purine metabolism, degradation and excretion of UA together with metabolites of intestinal flora, and suppression of gout inflammation, and is evaluated as a new therapeutic potential for gout and hyperuricemia to prevent renal damage and urolithiasis.

Dietary Galactose Increases the Expression of Mitochondrial OXPHOS Genes and Modulates the Carbohydrate Oxidation Pathways in Mouse Intestinal Mucosa

BackgroundProlonged lactation provides substantial health benefits, possibly because of galactose as part of milk sugar lactose. Isocaloric replacement of dietary glucose [16 energy%(en%)] with galactose within a normal diet (64en% carbohydrates) during a 3-wk postweaning period provided substantial benefits on short- and long-term physiologic and metabolic parameters at the whole-body level and liver in female mice, which might be attributable to intestinal function. ObjectivesThis study aimed to investigate if partial dietary replacement of glucose with galactose alters intestinal metabolism underlying hepatic health effects. MethodsProximal intestinal mucosa gene profiles in female mice were analyzed using RNAseq technology, validated, and correlated with hepatic health parameters. ResultsTranscriptome analysis revealed that the presence of galactose primarily affected the pathways involved in energy metabolism. A consistently higher expression was observed in the subset of mitochondrial transcripts (78 of 80, all P.adj < 0.1). Oxidative phosphorylation (OXPHOS) represented the most upregulated process (all top 10 pathways) independent of the total mitochondrial mass (P = 0.75). Moreover, galactose consistently upregulated carbohydrate metabolism pathways, specifically glycolysis till acetyl-CoA production and fructose metabolism. Also, the expression of transcripts involved in these pathways was negatively correlated with circulating serum amyloid A3 protein, a marker of hepatic inflammation [R (−0.61, −0.5), P (0.002, 0.01)]. Accordingly, CD163+ cells were decreased in the liver. Additionally, the expression of key fructolytic enzymes in the small intestinal mucosa was negatively correlated with triglyceride accumulation in the liver [R (−0.45, −0.4), P (0.03, 0.05)]. ConclusionsTo our knowledge, our results show for the first time the role of galactose as an OXPHOS activator in vivo. Moreover, the concept of intestinal cells acting as the body's metabolic gatekeeper is strongly supported, as they alter substrate availability and thereby contribute to the maintenance of metabolic homeostasis, protecting other organs, as evidenced by their potential ability to shield the liver from the potentially detrimental effects of fructose.

Kuijie decoction ameliorates ulcerative colitis by affecting intestinal barrier functions, gut microbiota, metabolic pathways and Treg/Th17 balance in mice

Ethnopharmacological relevanceCurrently, the clinical treatment is limited and difficult to achieve satisfactory results for ulcerative colitis (UC). The role of traditional Chinese medicine (TCM) in the treatment of UC is very complex. Kuijie decoction (KJD) as a classic TCM, is widely used in the clinical treatment of UC, but the mechanism of its action is still unclear. Aim of the studyThis study is to investigate the protective effects of KJD on UC and the underlying mechanisms. Materials and methodsThe experimental model of UC was induced by DSS, and KJD was introduced into the model at the same time. Clinical symptoms, including the body weight, colon length and colon histopathological, were used to measure the severity of colitis. The expression of inflammatory cytokines and tight junction proteins was quantified. The effect of KJD on intestinal flora and intestinal metabolism was determined by 16S rRNA and untargeted metabolomics analysis, respectively. The proportion of Th17 cells and Tregs in the spleen was examined by flow cytometry. ResultsMice treated with KJD showed significantly alleviated clinical symptoms and histological damage, such as more body weight gain, lower disease activity index (DAI) score, and longer colon length. The administration of KJD also led to the down-regulation of inflammatory mediators, upregulation of the expression of ZO-1, occludin and decreased claudin-2, as well as altered microbiota composition against DSS challenges (especially an increase of Lachnospiraceae). KJD enhanced the percentage of Treg cells but decreased the proportion of Th17 cells to maintain intestinal homeostasis by improving gut microbiota metabolism. ConclusionsIn summary, KJD maintained intestinal epithelial homeostasis by regulating epithelial barrier function, intestinal flora, and restoring Th17/Treg balance. KJD has the potential to be a Chinese medicine treatment for UC.

Integration of gut microbiome and serum metabolome revealed the effect of Qing-Wei-Zhi-Tong Micro-pills on gastric ulcer in rats

Ethnopharmacological relevanceQing-Wei-Zhi-Tong Micro-pills (QWZT) is herbal compound used in the treatment of GU, whose functions include clearing the stomach and fire, softening the liver and relieving pain. However, its mechanistic profile on host intestinal microbiota and metabolism has not been determined. Aim of the studyThe present study aimed to observe the healing effect of QWZT on acetic acid-induced gastric ulcer in a rat model and to preliminarily elucidate its possible therapeutic mechanism from the perspective of host intestinal microbiota and metabolism. Materials and methodsThe Wistar male rats (7 weeks old; weight 180–200 g) were randomly divided into normal control group (NC), acetic acid-induced gastric ulcer group (GU), and QWZT treatment group (High dose: 1250 mg/kg/day, Middle dose: 625 mg/kg/day, Low dose: 312.5 mg/kg/day) of 6 rats each. An acetic acid-induced gastric ulcer rat model was constructed based on anatomical surgery. QWZT (High dose, Middle dose, and Low dose) was used to treat gastric ulcer rats for 7 days by gavage. At the end of treatment, the body weight, macroscopic condition of gastric tissue ulcers, pathological changes (HE staining), inflammatory factors, oxidative stress factors, and endocrine factors were assessed in each group of rats. Fresh feces and serum from each group of rats were collected for microbiome and metabolome analysis on the machine, respectively. Drug-disease common targets and functional pathways were captured based on network pharmacology. The complex network of Herbs-Targets-Pathways-Metabolites-Microbiota interactions was constructed. Ultimately, Fecal Microbiota Transplantation (FMT) evaluated the contribution of gut microbiota in disease. ResultsQWZT increased the abundance of beneficial bacteria (Bacteroides, Alloprevotella, Rikenellaceae_RC9_gut_group, Lactobacillus, Lachnospiraceae_NK4A136_group, Parabacteroides, etc.), reduced the abundance of harmful bacteria (Micromonospora, Geobacter, Nocardioides, and Arenimonas, etc.), reduced the levels of inflammatory mediators (12,13-EpOME, 9,10-Epoxyoctadecenoic acid, SM(d18:1/16:0) and Leukotriene A4, etc.), restored host metabolic disorders (Linoleic acid metabolism, Glycerophospholipid metabolism, and Arachidonic acid metabolism), and regulated the level of cytokines (IL-6, TNF-a, SOD, MDA, PEG-2 and NO), ultimately exerting an anti-ulcer effect. Apart from that, FMT improved acetic acid-induced gastric ulcers in rats. ConclusionQWZT improved acetic acid-induced gastric ulcers in rats by remodeling intestinal microbiota and regulating host metabolism. This work may promote the process of developing and utilizing clinical applications of QWZT.

SAT031 The Effect Of Metformin On Increasing Glucose Metabolism And Secretion In The Distal Intestine

Abstract Disclosure: J. Nam: None. C. Kang: None. J. Oh: None. E. Wang: None. S. Lee: None. J. Hong: None. E. Lee: None. C. Ku: None. Object: Although the effect of metformin is widely known, little research has been performed on clinical significance and potential mechanism of increased intestinal glucose uptake which is commonly found in [18F]-fluoro-D-glucose (FDG) positron emission tomography. The aim of this study is to assess the altered glucose metabolism in the combined colon and terminal small intestine after metformin treatment. Material and Method: Radioactivity of FDG was measured in metformin treated mouse to evaluate the glucose uptake in the various tissue. qPCR and immunoblot were performed to examine the glucose metabolism in small intestine and colon. Autoradiography and gamma counts were used for measuring FDG uptake in small intestine and colon. IEC6 and Caco-2 cell lines were used for small intestine and colon respectively for in vitro experiment. Result: 150mg/kg metformin treatment for 7 days improved glucose homeostasis in c57BL6 mice (AUC 0.8- fold, p&amp;lt;0.05). Gradual increase in FDG absorption was observed along the intestine in an autoradiography and gamma counter. Especially distal ileum (9-fold, p &amp;lt;0.0001) and colon (15-fold, &amp;lt;0.0001) showed increased glucose uptake than proximal intestine (Duodenum no significance, Jejunum 3-fold, P&amp;lt;0.01). Interestingly, glucose content in the fecal flush was elevated in metformin treated mice (13.5-fold, p&amp;lt;0.01). In line with the in vivo result, metformin enhanced glucose uptake in IEC6 (3-fold, p&amp;lt;0.01) cell compared to the non-treat control cells (NT). qPCR and Immunoblot results showed that metformin treatment enhanced GLUT1 expression (1.6-fold, p&amp;lt;0.01) compared to the NT. Hexokinase2 (HK2), known as glycolysis marker, shown to be increased (1.4-fold, p&amp;lt;0.01) by the metformin treatment in IEC6 and Caco-2 cells compared to the NT. GLUT1 expression was also increased in the metformin treated mice small intestine and colon than in vehicle treated mice. Conclusion: Taken together, our data suggest that metformin increases the glucose metabolism of distal small intestine and colon by the upregulation of GLUT1 expression. Enhanced glucose metabolism induced by metformin was correlated with the improved glucose homeostasis. Our data suggests the novel mechanism of metformin in the G.I tract that involved to some extent in the disposal of excess glucose in in vitro and in vivo system. Presentation: Saturday, June 17, 2023

Quantitative Translation of Substrate Intrinsic Clearance from Recombinant CYP1A1 to Humans.

CYP1A1 is a cytochrome P450 family 1 enzyme that is mostly expressed in the extrahepatic tissues. To understand the CYP1A1 contribution to drug clearance in humans, we examined the in vitro-in vivo extrapolation (IVIVE) of intrinsic clearance (CLint) for a set of drugs that are in vitro CYP1A1 substrates. Despite being strong in vitro CYP1A1 substrates, 82% of drugs gave good IVIVE with predicted CLint within 2-3-fold of the observed values using human liver microsomes and hepatocytes, suggesting they were not in vivo CYP1A1 substrates due to the lack of extrahepatic contribution to CLint. Only three drugs (riluzole, melatonin and ramelteon) that are CYP1A2 substrates yielded significant underprediction of in vivo CLint up to 11-fold. The fold of CLint underprediction was linearly proportional to human recombinant CYP1A1 (rCYP1A1) CLint, indicating they were likely to be in vivo CYP1A1 substrates. Using these three substrates, a calibration curve can be developed to enable direct translation from in vitro rCYP1A1 CLint to in vivo extrahepatic contributions in humans. In vivo CYP1A1 substrates are planar and small, which is consistent with the structure of the active site. This is in contrast to the in vitro substrates, which include large and nonplanar molecules, suggesting rCYP1A1 is more accessible than what is in vivo. The impact of CYP1A1 on first-pass intestinal metabolism was also evaluated and shown to be minimal. This is the first study providing new insights on in vivo translation of CYP1A1 contributions to human clearance using in vitro rCYP1A1 data.

Perfluorooctanoic acid-induced metabolic disorder via enhancing metabolism of glutamine and fatty acids in human intestinal cells

Intestinal cell metabolism plays an important role in intestine health. Perfluorooctanoic acid (PFOA) exposure could disorder intestinal cell metabolism. However, the mechanisms regarding how the three carbon sources interact under PFOA stress remined to be understood. The present study aimed to dissect the interconnections of glucose, glutamine, and fatty acids in PFOA-treated human colorectal cancer (DLD-1) cells using 13C metabolic flux analysis. The abundance of glycolysis and tricarboxylic acid (TCA) cycle metabolites was decreased in PFOA-treated cells except for succinate, whereas most of amino acids were more abundant. Beside serine and glycine, the levels of metabolites derived from 13C glucose were reduced in PFOA-treated cells, and the pentose phosphate pathway flux was 1.4-fold higher in PFOA-treated cells than in the controls. In reductive glutamine pathway, higher labeled enrichment of citrate, malate, fumarate, and succinate was observed for PFOA-treated cells. The contribution of glucose to fatty acid synthesis in PFOA-treated cells decreased while the contribution of glutamine to fatty acid synthesis increased. Additionally, synthesis of TCA intermediates from fatty acid β-oxidation was promoted in PFOA-treated cells. All results suggested that metabolic remodeling could happen in intestinal cells exposed to PFOA, which was potentially related to PFOA toxicity relevant with the loss of glucose in biomass synthesis and energy metabolism.

Dietary phytosterols supplementation improves the growth performance and decreases the abdominal fat of broiler chickens by regulating intestinal epithelial structure and microbiota

Phytosterols, plant-derived fatty compounds, were reported to be bioactive for animals and promote the growth of broilers. Whether dietary phytosterols could improve the growth performance of broilers by regulating intestinal morphology and microbiota is still unclear and limited. Thus, our experiment aimed to evaluate the effects of dietary phytosterols on the growth performance, intestinal morphology, and microbiota of broilers. A total of 200 male Arbor Acres broiler chickens (1 day old) were randomly assigned to 2 treatment groups with 5 replicates of 20 birds each, (1) basic corn-soybean diet; (2) basic corn-soybean diet supplemented with 25 mg/kg phytosterols. Dietary supplementation of phytosterols at 25 mg/kg increased the average daily gain and reduced the feed conversion rate of broilers (P < 0.05), but did not affect average daily feed intake (P > 0.05). It reduced the abdominal fat yield and serum triglyceride and low-density lipoprotein cholesterol levels in broilers (P < 0.05). Phytosterols treatment increased villus height to crypt depth ratio and up-regulated the mRNA expression of tight junction-related genes in both jejunal (i.e., ZO-2, ZO-3, and claudin-3) and ileal (i.e., claudin-1 and claudin-2) tissues (P < 0.05). Additionally, dietary phytosterols significantly down-regulated the mRNA expression of pro-inflammatory cytokine (IL-1β and IL-6) in the jejunal tissues (P < 0.05), and up-regulated that of anti-inflammatory cytokine (IL-4 and IL-10) in the ileal tissues (P < 0.05). Moreover, broilers fed with dietary phytosterols had a higher concentration of lactic acid in the caecal digesta (P < 0.05). Dietary supplementation with phytosterols decreased the alpha diversity of the bacterial community (P < 0.05) and increased the relative abundance of probiotics (i.e., Lactobacillus) in the intestinal digesta of broilers (P < 0.05). PICRUSt2 analyses revealed that phytosterols enhanced the bacterial metabolic pathways of amino sugar and nucleotide sugar metabolism and fatty acid metabolism. Dietary supplementation of phytosterols could improve the growth performance and reduce the abdominal fat yield of broilers by altering their intestinal epithelial structure, lipid metabolism and bacterial community.

Altered Intestinal Microbial Flora and Metabolism in Patients with Idiopathic Membranous Nephropathy

Introduction: Dysbiosis of the intestinal microbiome and related metabolites have been observed in chronic kidney disease, yet their roles in idiopathic membranous nephropathy (IMN) are poorly understood. Methods: In this study, we describe the variation of intestinal bacteria and fecal metabolites in patients with IMN in Chinese population. Stool samples were collected from 41 IMN patients at the beginning of diagnosis confirmation and 41 gender- and age-matched healthy control (HC). Microbial communities are investigated by sequencing of 16S rRNA genes and functional profiles predicted using Tax4Fun, and the correlation between intestinal bacteria and IMN clinical characteristics is also analyzed. Untargeted metabolomic analysis is performed to explore the relationship between colon’s microbiota and fecal metabolites. Results: IMN gastrointestinal microbiota demonstrates lower richness and diversity compared to HC, and exhibits a marked taxonomic and inferred functional dysbiosis when compared to HC. Some genera are closely related to the clinical parameters, such as Citrobacter and Akkermansia. Twenty characteristic microbial biomarkers are selected to establish a disease prediction model with a diagnostic accuracy of 93.53%. Fecal metabolomics shows that tryptophan metabolism is reduced in IMN patients but uremic toxin accumulation in feces is not noticeable. Fecal microbiota transplantation demonstrates that gut dysbiosis impairs gut permeability in microbiota-depleted mice and induces NOD-like receptor activation in the kidneys. Conclusions: Clarifying the changes in intestinal microbiota in IMN patients will help further know the pathogenesis of this disease, and microbiota-targeted biomarkers will provide a potentially powerful tool for diagnosing and treating IMN.

Microbiota-gut-brain axis drives overeating disorders

Overeating disorders (ODs), usually stemming from dieting history and stress, remain a pervasive issue in contemporary society, with the pathological mechanisms largely unresolved. Here, we show that alterations in intestinal microbiota are responsible for the excessive intake of palatable foods in OD mice and patients with bulimia nervosa (BN). Stress combined with a history of dieting causes significant changes in the microbiota and the intestinal metabolism, which disinhibit the vagus nerve terminals in the gut and thereby lead to a subsequent hyperactivation of the gut-brain axis passing through the vagus, the solitary tract nucleus, and the paraventricular nucleus of the thalamus. The transplantation of a probiotic Faecalibacterium prausnitzii or dietary supplement of key metabolites restores the activity of the gut-to-brain pathway and thereby alleviates the OD symptoms. Thus, our study delineates how the microbiota-gut-brain axis mediates energy balance, unveils the underlying pathogenesis of the OD, and provides potential therapeutic strategies.