Long-Term Triclocarban Exposure Induced Enterotoxicity by Triggering Intestinal AhR-Mediated Inflammation and Disrupting Microbial Community in Mice.

Exposure to triclocarban (TCC), a commonly used antibacterial agent, has been shown to induce significant intestine injuries and colonic inflammation in mice. However, the detailed mechanisms by which TCC exposure triggered enterotoxicity remain largely unclear. Herein, intestinal toxicity effects of long-term and chronic TCC exposure were investigated using a combination of histopathological assessments, metagenomics, targeted metabolomics, and biological assays. Mechanically, TCC exposure caused induction of intestinal aryl hydrocarbon receptor (AhR) and its transcriptional target cytochrome P4501A1 (Cyp1a1) leading to dysfunction of the gut barrier and disruption of the gut microbial community. A large number of lipopolysaccharides (LPS) are released from the gut lumen into blood circulation owing to the markedly increased permeability and gut leakage. Consequently, toll-like receptor-4 (TLR4) and NF-κB signaling pathways were activated by high levels of LPS. Simultaneously, classic macrophage phenotypes were switched by TCC, shown with marked upregulation of macrophage M1 and downregulation of macrophage M2 that was accompanied by striking upregulation of proinflammatory factors such as Il-1ß, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

Dietary Isoquercetin Ameliorates Bone Loss via Restoration of the Gut Microbiota and Lipopolysaccharide-Triggered Inflammatory Status in Ovariectomy Mice.

Osteoporosis is one of the skeletal degenerative diseases accompanied by bone loss and microstructure disruption. Given that the gut-bone signaling axis highly contributes to bone health, here, dietary isoquercetin (IQ) was shown to effectively improve postmenopausal osteoporosis (PMO) in an ovariectomy (OVX) mouse model through the modulation of the gut-bone cross-talk. An in vivo study showed that OVX induced striking disruption of the microbial community, subsequently causing gut leakage and gut barrier dysfunction. As a result, lipopolysaccharide (LPS)-triggered inflammatory cytokines released from the intestine to bone marrow were determined to be associated with bone loss in OVX mice. Long-term dietary IQ effectively improved microbial community and gut barrier function in the OVX mice and thus markedly improved bone loss and host inflammatory status by repressing the NF-κB signaling pathway. An in vitro study further revealed that IQ treatments dose-dependently inhibited LPS-induced inflammation and partly promoted the proliferation and differentiation of osteoblasts. These results provide new evidence that dietary IQ has the potential for osteoporosis treatment.

Discovery of a novel small molecule with efficacy in protecting against inflammation in vitro and in vivo by enhancing macrophages activation.

Immune response and inflammation highly contribute to many metabolic syndromes such as inflammatory bowel disease (IBD), ageing and cancer with disruption of host metabolic homeostasis and the gut microbiome. Icariin-1 (GH01), a small-molecule flavonoid derived from Epimedium, has been shown to protect against systemic inflammation. However, the molecular mechanisms by which GH01 ameliorates ulcerative colitis via regulation of microbiota-mediated macrophages polarization remain elusive. In this study, we found that GH01 effectively ameliorated dextran sulfate sodium (DSS)-induced colitis symptoms in mice. Disruption of intestinal barrier function, commensal microbiota and its metabolites were also significantly restored by GH01 in a dose-dependent manner. Of note, we also found that GH01 enhanced phagocytic ability of macrophages and switched macrophage phenotype from M1 to M2 both in vitro and in vivo. Such macrophage polarization was highly associated with intestinal barrier integrity and the gut microbial community. Consequently, GH01 exhibited strong anti-inflammatory capacity by inhibiting TLR4 and NF-κB pathways and proinflammatory factors (IL-6). These findings suggested that GH01 might be a potential nutritional intervention strategy for IBD treatment with the gut microbial community-meditated macrophage as the therapeutic targets.

Multiomics analyses reveal dose-dependent effects of dicofol exposure on host metabolic homeostasis and the gut microbiota in mice.

BACKGROUND: Environmental exposure to dicofol (DCF), one of common organochlorine pesticides (OCPs) widely used for controlling agricultural pests, elicits a potential risk for human health due to its toxicity. However, potential physiological hazards of oral DCF exposure remain largely unknown. METHODS: Mice were exposed to relatively chronic and subacute DCF at different doses (5, 20 and 100 mg/kg) by gavage for 2 weeks. 1H NMR-based metabolomics was used to explore alterations of metabolic profiling induced by DCF exposure. Targeted metabolomics was subsequently employed to investigate the dose-dependent effects of oral DCF exposure on lipid metabolism and the gut microbiota-derived metabolites of mice. 16S rRNA gene sequencing was further employed to evaluate the changes of gut community of mice exposed to DCF. RESULTS: Oral exposure to DCF dose-dependently induced liver injury, manifested by hepatic lipogenesis, inflammation and liver dysfunction of mice. Typically, DCF exposure disrupted host fatty acids metabolism that were confirmed by marked alteration in the levels of related genes. DCF exposure also dose-dependently caused dysbiosis of the gut bacteria and its metabolites including altered microbial composition accompanied by inhibition of bacterial fermentation. CONCLUSION: These results provide metabolic evidence that DCF exposure dose-dependently induces liver lipidosis and disruption of the gut microbiota in mice, which enrich our views of molecular mechanism of DCF hepatoxicity.

A novel small molecule effectively ameliorates estrogen deficiency-induced osteoporosis by targeting the gut-bone signaling axis.

Postmenopausal osteoporosis stems mainly from estrogen deficiency leading to a gut microbiome-dependent disruption of host systemic immunity. However, the underlying mechanisms of estrogen deficiency-induced bone loss remain elusive and novel pharmaceutical intervention strategies for osteoporosis are needed. Here we reveal that ovariectomy (ovx)-induced estrogen deficiency in C57BL/6 mice causes significant disruption of gut microbiota composition, consequently leading to marked destruction of intestinal barrier function and gut leakage. As a result, signals transportation between intestinal microbiota and T cells from the gut to bone marrow is identified to contribute to osteoclastogenesis in ovx mice. Notably, we show that icariside I (GH01), a novel small molecule naturally occurring in Herbal Epimedium, has potential to alleviate or prevent ovx-induced bone loss in mice through regulation of gut-bone signaling axis. We find that GH01 treatment can effectively restore the gut microbiota composition, intestinal barrier function and host immune status markedly altered in ovx mice, thus significantly ameliorating bone loss and osteoporosis. These findings not only provide systematic understanding of the gut-immunity-bone axis-associated pathophysiology of osteoporosis, but also demonstrate the high potential of GH01 for osteoporosis treatment by targeting the gut-bone signaling axis.

Triclocarban exposure aggravates dextran sulfate sodium-induced colitis by deteriorating the gut barrier function and microbial community in mice.

Triclocarban (TCC) is an antibacterial component widely used in personal care products with potential toxicity possessing public health issues. Unfortunately, enterotoxicity mechanisms of TCC exposure remain largely unknown. Using a combination of 16S rRNA gene sequencing, metabolomics, histopathological and biological examinations, this study systematically explored the deteriorating effects of TCC exposure on a dextran sulfate sodium (DSS)-induced colitis mouse model. We found that TCC exposure at different doses significantly aggravated colitis phenotypes including shortened colon length and altered colonic histopathology. Mechanically, TCC exposure further disrupted intestinal barrier function, manifested by significant downregulation of the number of goblet cells, mucus layer thickness and expression of junction proteins (MUC-2, ZO-1, E-cadherin and Occludin). The gut microbiota composition and its metabolites such as short-chain fatty acids (SCFAs) and tryptophan metabolites were also markedly altered in DSS-induced colitis mice. Consequently, TCC exposure markedly exacerbated colonic inflammatory status of DSS-treated mice by activating NF-κB pathway. These findings provided new evidence that TCC could be an environmental hazards for development of IBD or even colon cancer.

Dietary Isoquercetin Reduces Hepatic Cholesterol and Triglyceride in NAFLD Mice by Modulating Bile Acid Metabolism via Intestinal FXR-FGF15 Signaling.

Isoquercetin, a monosaccharide flavonoid, was recently reported to have significant amelioration effects on high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) of mice. However, the underlying mechanism of hepatic cholesterol and triglyceride improvement in mice fed HFD by isoquercetin remains unclear. Here, a combination of 16S rRNA gene sequencing, targeted quantification of bile acids (BAs), and biological assays was employed to investigate the beneficial effects of isoquercetin on NAFLD in mice. The results showed that dietary isoquercetin markedly modulated the BAs profiling in various samples such as liver, serum, intestine, and feces. We found that dietary isoquercetin promoted BA biosynthesis via the activation of alternative pathways and inhibition of intestinal FXR-Fgf15 signaling, thus reducing 13.2% hepatic cholesterol and 16.05% triglyceride in NAFLD mice. Dietary isoquercetin also regulated a series of receptors mediating correspondent processes of BA transportation, reabsorption, and excretion. Of particular note, dietary isoquercetin significantly modulated cross-talk between BAs and specific gut bacteria of NAFLD mice. These findings revealed that long-term intake of isoquercetin plays beneficial roles in the prevention or intervention of fatty liver disease.

A Novel Prenylflavonoid Icariside I Ameliorates Estrogen Deficiency-Induced Osteoporosis via Simultaneous Regulation of Osteoblast and Osteoclast Differentiation.

Regulation of osteoblast-mediated bone formation and osteoclast-mediated bone resorption is crucial for bone health. Currently, most clinical drugs for osteoporosis treatment such as bisphosphonates are commonly used to inhibit bone resorption but unable to promote bone formation. In this study, we discovered for the first time that icariside I (GH01), a novel prenylflavonoid isolated from Epimedium, can effectively ameliorate estrogen deficiency-induced osteoporosis with enhancement of trabecular and cortical bone in an ovariectomy (OVX) mouse model. Mechanistically, our in vitro results showed that GH01 repressed osteoclast differentiation and resorption through inhibition of RANKL-induced TRAF6-MAPK-p38-NFATc1 cascade. Simultaneously, we also found that GH01 dose-dependently promoted osteoblast differentiation and formation by inhibiting adipogenesis and accelerating energy metabolism of osteoblasts. In addition, both in vitro and in vivo studies also suggested that GH01 is not only a non-toxic natural small molecule but also beneficial for restoration of liver injury in OVX mice. These results demonstrated that GH01 has great potential for osteoporosis treatment by simultaneous regulation of osteoblast and osteoclast differentiation.

Structural Insights into Amelioration Effects of Quercetin and Its Glycoside Derivatives on NAFLD in Mice by Modulating the Gut Microbiota and Host Metabolism.

The sugar moieties of natural flavonoids determine their absorption, bioavailability, and bioactivity in humans. To explore structure-dependent bioactivities of quercetin, isoquercetin, and rutin, which have the same basic skeleton linking different sugar moieties, we systemically investigated the ameliorative effects of dietary these flavonoids on high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) of mice. Our results revealed that isoquercetin exhibits the strongest capability in improving NAFLD phenotypes of mice, including body and liver weight gain, glucose intolerance, and systemic inflammation in comparison with quercetin and rutin. At the molecular level, dietary isoquercetin markedly ameliorated liver dysfunction and host metabolic disorders in mice with NAFLD. At the microbial level, the three flavonoids compounds, especially isoquercetin, can effectively regulate the gut microbiota composition, such as genera Akkermansia, Bifidobacterium, and Lactobacillus, which were significantly disrupted in NAFLD mice. These comparative findings offer new insights into the structure-dependent activities of natural flavonoids for NAFLD treatment.

Multiomics Analyses Reveal That Long-Term Intake of Hesperetin-7-O-glucoside Modulates the Gut Microbiota and Bile Acid Metabolism in Mice.

Hesperetin-7-O-glucoside (Hes-7-G) is a typical flavonoid monoglucoside, which can be generated from hesperidin with the removal of rhamnose by hydrolysis. Untargeted and targeted metabolomics together with 16S rRNA gene sequencing were employed to explore the exact absorption site of Hes-7-G and its beneficial effect in mice. Intestinal 1H nuclear magnetic resonance (NMR)-based metabolomics screening showed that Hes-7-G is mainly metabolized in the small intestine of mice, especially the ileum segment. Quantification analysis of bile acids (BAs) in the liver, intestinal tract, feces, and serum of mice suggests that Hes-7-G intake accelerates the processes of biosynthesis and excretion of BAs, thus promoting digestion and lowing hepatic cholesterol and triglyceride. 16S rRNA gene sequencing reveals that Hes-7-G significantly elevates the diversity of the gut microbiota in mice, especially those bacteria associated with BA secondary metabolism. These results demonstrated that long-term dietary Hes-7-G plays beneficial roles in health by modulating the gut bacteria and BA metabolism in mice.

Acute and subchronic exposure of cyadox induced metabolic and transcriptomic disturbances in Wistar rats.

Cyadox, a potential antimicrobial growth promoter, has been widely studied and prospected to be used as an additive in livestock and poultry feed. Although high cyadox exposure has been reported to cause toxicity, the exact metabolic effects are not fully understood. Our study aim is to evaluate the metabolic effects of cyadox using comprehensive methods including serum clinical chemical test, histopathology analysis, metabolomics, and transcriptomics profile analysis. One single acute dosage over 7-day course and one subchronic 90-day dietary ingestion of cyadox intervention were conducted on the Wistar rats separately. Dose-dependent alterations were shown in the metabolism of the urine, kidney, plasma, and liver by metabolomics analysis. We further investigated gene expressions of the liver administered with high dose of cyadox for 12 weeks. Top sixty-six differentially expressed genes involved in the pathways, including xenobiotic (cyadox) metabolism, lipid metabolism, energy metabolism, nucleic acid metabolic process, inflammatory response, and response to the oxidative stress, which were in concordance with these metabolic alternations. Our study provided a comprehensive information on how cyadox modulates the metabolism and gene expressions, which is vital when considering the safe application of cyadox.

Icariside I - A novel inhibitor of the kynurenine-AhR pathway with potential for cancer therapy by blocking tumor immune escape.

BACKGROUND: Although therapeutic antibodies against immune checkpoints such as PD-1/PD-L1 have achieved unprecedented success in clinical tumor patients, there are still many patients who are ineffective or have limited responses to immune checkpoint blockade (ICB). Discovery of novel strategies for cancer immunotherapy including natural small molecules is needed. METHODS: Owing to its extremely low content in Epimedium genus, we firstly constructed a microbial cell factory to enzymatically biosynthesize icariside I, a natural flavonoid monosaccharide from Herbal Epimedium. Using a combination of targeted MS-based metabolomics, flow cytometric analysis, and biological assays, the therapeutic potentials of icariside I were subsequently investigated in vivo and in vitro. RESULTS: We find that icariside I markedly downregulates a series of intermediate metabolites such as kynurenine, kynurenic acid and xanthurenic acid and corresponding key enzymes involved in kynurenine-AhR pathway in both tumor cells and tumor-bearing mice. In vivo, oral administration of icariside I downregulates SLC7A8 and PAT4 transporters and AhR, thus inhibiting nuclear PD-1 in CTLs. Moreover, icariside I significantly upregulates CD8 + T cells in both peripheral blood and tumor tissues of tumor-bearing mice. Consequently, interferon-γ (IFN-γ) secreted by CD8 + T cells suppresses tumor growth through activation of JAK1-STAT1 signaling, thus inducing tumor cell apoptosis. CONCLUSIONS: These results suggest that icariside I could be an effective small molecule drug for tumor immunotherapy by blocking kynurenine-AhR pathway and tumor immune escape.

Characterization of triclosan-induced hepatotoxicity and triclocarban-triggered enterotoxicity in mice by multiple omics screening.

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether, TCS) and triclocarban (3,4,4'-trichloro-carbanilide, TCC) are two antimicrobial agents commonly used for personal care products. Previous studies primarily focused on respective harmful effects of TCS and TCC. In terms of their structural similarities and differences, however, the structure-toxicity relationships on health effects of TCS and TCC exposure remain unclear. Herein, global 1H NMR-based metabolomics was employed to screen the changes of metabolic profiling in various biological matrices including liver, serum, urine, feces and intestine of mice exposed to TCS and TCC at chronic and acute dosages. Metagenomics was also applied to analyze the gut microbiota modulation by TCS and TCC exposure. Targeted MS-based metabolites quantification, histopathological examination and biological assays were subsequently conducted to supply confirmatory information on respective toxicity of TCS and TCC. We found that oral administration of TCS mainly induced significant liver injuries accompanied with inflammation and dysfunction, hepatic steatosis fatty acids and bile acids metabolism disorders; while TCC exposure caused marked intestine injuries leading to striking disruption of colonic morphology, inflammatory status and intestinal barrier integrity, intestinal bile acids metabolism and microbial community. These comparative results provide novel insights into structure-dependent mechanisms of TCS-induced hepatotoxicity and TCC-triggered enterotoxicity in mice.

Quantitative structure-retention relationship for reliable metabolite identification and quantification in metabolomics using ion-pair reversed-phase chromatography coupled with tandem mass spectrometry.

Hydrophilic metabolites are essential for all biological systems with multiple functions and their quantitative analysis forms an important part of metabolomics. However, poor retention of these metabolites on reversed-phase (RP) chromatographic column hinders their effective analysis with RPLC-MS methods. Herein, we developed a method for detecting hydrophilic metabolites using the ion-pair reversed-phase liquid-chromatography coupled with mass spectrometry (IPRP-LC-MS/MS) in scheduled multiple-reaction-monitoring (sMRM) mode. We first developed a hexylamine-based IPRP-UHPLC-QTOFMS method and experimentally measured retention time (tR) for 183 hydrophilic metabolites. We found that tRs of these metabolites were dominated by their electrostatic potential depending upon the numbers and types of their ionizable groups. We then systematically investigated the quantitative structure-retention relationship (QSRR) and constructed QSRR models using the measured tR. Subsequently, we developed a retention time predictive model using the random-forest regression algorithm (r2 = 0.93, q2 = 0.70, MAE = 1.28 min) for predicting metabolite retention time, which was applied in IPRP-UHPLC-MS/MS method in sMRM mode for quantitative metabolomic analysis. Our method can simultaneously quantify more than 260 metabolites. Moreover, we found that this method was applicable for multiple major biological matrices including biofluids and tissues. This approach offers an efficient method for large-scale quantitative hydrophilic metabolomic profiling even when metabolite standards are unavailable.

Long-term chronic exposure to di-(2-ethylhexyl)-phthalate induces obesity via disruption of host lipid metabolism and gut microbiota in mice.

BACKGROUND: Numerous epidemiological findings have shown that di-(2-ethylhexyl)-phthalate (DEHP), one of industrial plasticizers with endocrine-disrupting properties, positively contributes to high incidence of obesity. However, potential pathogenesis of dietary DEHP exposure-induced obesity remains largely unknown. METHODS: Chronic DEHP exposure at different doses (0.05 and 5 mg/kg body weight) to mice had been continuously lasted for 14 weeks through the diet. A combination of targeted quantitative metabolomics (LC/GC-MS) with global 1H NMR-based metabolic profiling to explore the effects of dietary DEHP exposure with different doses on host lipid metabolism of mice. Metagenomics (16S rRNA gene sequencing) was also employed to examine the alterations of gut microbiota composition in the cecal contents of mice after dietary DEHP exposure. RESULTS: Dietary exposure to DEHP at both doses induced weight gain and hepatic lipogenesis of mice by promoting the uptake of fatty acids and disrupting phospholipids and choline metabolism. Dietary DEHP exposure altered the gut microbiota community with disruption of intestinal morphology and reduction of Firmicutes to Bacteroidetes ratio in the cecal contents of mice. Furthermore, DEHP exposure activated gut microbiota fermentation process producing excess short chain fatty acids of mice. CONCLUSION: These findings provide systematic evidence that long-term chronic DEHP exposure induces obesity through disruption of host lipid metabolism and gut microbiota in mice, which not only confirm the epidemiological results, but also expand our understanding of metabolic diseases caused by environmental pollutants exposure.

In Vitro and In Vivo Studies Reveal that Hesperetin-7-O-glucoside, a Naturally Occurring Monoglucoside, Exhibits Strong Anti-inflammatory Capacity.

Hesperetin-7-O-glucoside (Hes-7-G) is a naturally occurring flavonoid monoglucoside in Citri Reticulatae Pericarpium and exhibits relatively high biological activities. To explore the anti-inflammatory capacity of dietary Hes-7-G, lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and dextran sodium sulfate (DSS)-induced colitis mice were used here as in vitro and in vivo inflammation models. The results showed that Hes-7-G (5 µM) significantly restored cellular metabolic disorders and inflammation in LPS-stimulated RAW264.7 macrophages. In the in vivo study, dietary Hes-7-G (1 mg/kg body weight) markedly alleviated the inflammatory status in DSS-induced colitis mice, manifested by the recovered colon length from 5.91 ± 0.66 to 6.45 ± 0.17 cm, histopathological changes, and mRNA levels of colonic inflammatory factors including Tnf-α and Il-22. Furthermore, dietary Hes-7-G not only profoundly regulated the gut microbiota composition including phyla Bacteroidetes, Cyanobacteria, Desulfobacterota, and Deferribacteres and genus Enterorhabdus, Prevotellaceae, Gastranaerophilales, Enterococcus, Intestinimonas, Ruminococcaceae, and Eubacterium in the cecal contents but also especially adjusted the co-metabolites such as short chain fatty acids and indole metabolites (indole-3-propionic, indole acetic acid), which were markedly altered by DSS treatment in mice. These findings demonstrated that Hes-7-G has strong anti-inflammatory activity in vitro and in vivo and potential preventive or therapeutic effects for chronic inflammation diseases.

Microbiome analysis combined with targeted metabolomics reveal immunological anti-tumor activity of icariside I in a melanoma mouse model.

Recent studies report that the gut microbiome can enhance systemic and antitumor immunity by modulating responses to antibody immunotherapy in melanoma patients. In this study, we found that icariside I, a novel anti-cancer agent isolated from Epimedium, significantly inhibited B16F10 melanoma growth in vivo through regulation of gut microbiota and host immunity. Oral administration of icariside I improved the microbiota community structure with marked restoration of Lactobacillus spp. and Bifidobacterium spp. abundance in the cecal contents of tumor-bearing mice. We also found that icariside I improves the levels of microbiota-derived metabolites such as short-chain fatty acids (SCFAs) and indole derivatives, consequently promoting repair of the intestinal barrier and reducing systemic inflammation of tumor-bearing mice. Icariside I exhibited strong immunological anti-tumor activity, directly manifested by up-regulation of multiple lymphocyte subsets including CD4+ and CD8+ T cells or NK and NKT cells in peripheral blood of tumor-bearing mice. Collectively, these results suggest that icariside I, via its microbiome remodeling and host immune regulation properties, may be developed as an anticancer drug.

Gut Microbiota and Its Metabolite Deoxycholic Acid Contribute to Sucralose Consumption-Induced Nonalcoholic Fatty Liver Disease.

As important signal metabolites within enterohepatic circulation, bile acids (BAs) play a pivotal role during the occurrence and development of diet-induced nonalcoholic fatty liver disease (NAFLD). Here, we evaluated the functional effects of BAs and gut microbiota contributing to sucralose consumption-induced NAFLD of mice. The results showed that sucralose consumption significantly upregulated the abundance of intestinal genera Bacteroides and Clostridium, which produced deoxycholic acid (DCA) accumulating in multiple biological matrixes including feces, serum, and liver of mice. Subsequently, elevated hepatic DCA, one of the endogenous antagonists of the farnesol X receptor (Fxr), inhibited hepatic gene expression including a small heterodimer partner (Shp) and Fxr leading to sucralose-induced NAFLD in mice. Dietary supplements with fructo-oligosaccharide or metformin markedly restored genera Bacteroides and Clostridium abundance and the DCA level of sucralose-consuming mice, which eventually ameliorated NAFLD. These findings highlighted the effects of gut microbiota and its metabolite DCA on sucralose-induced NAFLD of mice.

Impaired Intestinal Akkermansia muciniphila and Aryl Hydrocarbon Receptor Ligands Contribute to Nonalcoholic Fatty Liver Disease in Mice.

Noncaloric artificial sweeteners (NAS) are extensively introduced into commonly consumed drinks and foods worldwide. However, data on the health effects of NAS consumption remain elusive. Saccharin and sucralose have been shown to pass through the human gastrointestinal tract without undergoing absorption and metabolism and directly encounter the gut microbiota community. Here, we aimed to identify a novel mechanism linking intestinal Akkermansia muciniphila and the aryl hydrocarbon receptor (AHR) to saccharin/sucralose-induced nonalcoholic fatty liver disease (NAFLD) in mice. Saccharin/sucralose consumption altered the gut microbial community structure, with significant depletion of A. muciniphila abundance in the cecal contents of mice, resulting in disruption of intestinal permeability and a high level of serum lipopolysaccharide, which likely contributed to systemic inflammation and caused NAFLD in mice. Saccharin/sucralose also markedly decreased microbiota-derived AHR ligands and colonic AHR expression, which are closely associated with many metabolic syndromes. Metformin or fructo-oligosaccharide supplementation significantly restored A. muciniphila and AHR ligands in sucralose-consuming mice, consequently ameliorating NAFLD.IMPORTANCE Our findings indicate that the gut-liver signaling axis contributes to saccharin/sucralose consumption-induced NAFLD. Supplementation with metformin or fructo-oligosaccharide is a potential therapeutic strategy for NAFLD treatment. In addition, we also developed a new nutritional strategy by using a natural sweetener (neohesperidin dihydrochalcone [NHDC]) as a substitute for NAS and free sugars.

Metabolomics safety assessments of microcystin exposure via drinking water in rats.

Drinking water exposure to microcystin-leucine-arginine (MC-LR), the most widely occurring cyanotoxins, poses a highly potential risk for human health. However, the health risk of MC-LR exposure at current guideline value in drinking water has not yet entirely evaluated. In the current study, we used 1H NMR-based metabolomics combined with targeted metabolic profiling by GC/LC-MS to explore the toxic effects of MC-LR exposure at environmentally relevant concentrations via drinking water in rats. The results revealed that multiple biological consequences of MC-LR exposure on host metabolism in rats. Both relatively low and high doses of MC-LR used here induced hepatic lipogenesis and inflammation. While only relatively high dose MC-LR (10 µg/L) in drinking water caused more metabolic disorders including inhibition of gluconeogenesis and promotion of ß-oxidation of fatty acid. Although the dose of 1.0 µg/L MC-LR is extremely low for rats, alterations of metabolic profiles were unexpectedly found in rat liver and serum, alarming potential health risk of MC-LR at the WHO guideline level.