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.

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.

Metabolic Changes of Fusarium graminearum Induced by TPS Gene Deletion.

Fusarium head blight (FHB) mainly resulting from Fusarium graminearum (Fg) Schwabe is a notorious wheat disease causing huge losses in wheat production globally. Fg also produces mycotoxins, which are harmful to human and domestic animals. In our previous study, we obtained two Fg mutants, TPS1- and TPS2-, respectively, with a single deletion of trehalose 6-phosphate synthase (TPS1) and trehalose 6-phosphate phosphatase (TPS2) compared with the wild type (WT). Both mutants were unable to synthesize trehalose and produced fewer mycotoxins. To understand the other biochemical changes induced by TPS gene deletion in Fg, we comprehensively analyzed the metabolomic differences between TPS- mutants and the WT using NMR together with gas chromatography-flame ionization detection/mass spectrometry. The expression of some relevant genes was also quantified. The results showed that TPS1- and TPS2- mutants shared some common metabolic feature such as decreased levels for trehalose, Val, Thr, Lys, Asp, His, Trp, malonate, citrate, uridine, guanosine, inosine, AMP, C10:0, and C16:1 compared with the WT. Both mutants also shared some common expressional patterns for most of the relevant genes. This suggests that apart from the reduced trehalose biosynthesis, both TPS1 and TPS2 have roles in inhibiting glycolysis and the tricarboxylic acid cycle but promoting the phosphopentose pathway and nucleotide synthesis; the depletion of either TPS gene reduces the acetyl-CoA-mediated mycotoxin biosynthesis. TPS2- mutants produced more fatty acids than TPS1- mutants, suggesting different roles for TPS1 and TPS2, with TPS2- mutants having impaired trehalose biosynthesis and trehalose 6-phosphate accumulation. This may offer opportunities for developing new fungicides targeting trehalose biosynthesis in Fg for FHB control and mycotoxin reduction in the FHB-affected cereals.

Dose-Dependent Effects of Triclocarban Exposure on Lipid Homeostasis in Rats.

Environmental exposure to triclocarban (TCC), a common antibacterial agent widely used in thousands of personal care products, poses a potential risk for human health. Previous in vitro studies about biological effects of TCC have yielded a variety of inconsistent results and apparently not been verified in vivo. In the current study, dose-dependent effects of TCC exposure on lipid homeostasis in rats were investigated using a combination of untargeted 1H NMR metabolomics, targeted metabolite profiling (LC/GC-MS), histopathological assessments, and biological assays. Our results revealed that TCC dose-dependently activated aryl hydrocarbon receptor (AHR) and its transcriptional targets such as Cyp1a1 and Cyp1b1 in the liver of rats, suggesting that TCC may be a potent AHR agonist. Although TCC exhibited dose-dependent toxicity, oral exposure with relatively low dose TCC caused more significant hepatic lipogenesis of rats than relatively high and moderate doses of TCC. It was mainly manifested by histopathological observations and promotion of de novo fatty acid, phospholipid, and ceramide biosynthesis and gut microbiota fermentation. Our findings provide new insights into health effects of TCC exposure with different dosages in vivo, especially on the induction and progression of nonalcoholic fatty liver disease, and further our understanding in the pathogenesis of metabolic diseases induced by environmental pollutants.

Quantitative analysis of 10 classes of phospholipids by ultrahigh-performance liquid chromatography tandem triple-quadrupole mass spectrometry.

Phospholipids are the main constituents of biological membranes and their biological function has been increasingly recognized. Therefore, there is an unmet need to develop methods capable of quantifying a wide range of phospholipids with high sensitivities and high throughput. We employed an ultrahigh-performance liquid chromatography system coupled to a triple-quadrupole mass spectrometer (UHPLC-MS) and developed a method that can quantitatively analyze 10 major classes of phospholipids in biological samples in 11 min. These are phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylserine, sphingomyelin, lysophosphatidic acid, lysophosphatidylcholine and lysophosphatidylethanolamine. The limit of detection (LOD) and limit of quantitation (LOQ) are 0.04-33 pmol mL-1 and 0.1-110 pmol mL-1, respectively. The method takes three steps: first and second steps identified phospholipid structures in a mixture containing aliquots of all the samples using the combinations of multiple reaction monitoring (MRM), product ion scan and retention time in the positive and negative ion modes. These steps enabled the identification of phospholipids present in the samples and provided information on efficient sample analysis in the final step of sample quantitative analysis. We have developed fast and sensitive label-free quantitation with normalization of the acyl chain length to achieve more accurate quantification. The method developed was applied to analyze 6 different biological samples (plasma, cells and tissues) for applicability validation, where a total of 308 phospholipid species across 10 phospholipid classes were identified and 295 phospholipid species were quantified. The method is highly efficient, sensitive, and is universally applicable.

Interspecies Developmental Differences in Metabonomic Phenotypes of Lycium ruthenicum and L. barbarum Fruits.

Fruits of Lycium ruthenicum (LR) and L. barbarum (LB) in Solanaceae family contain abundant bioactive metabolites used widely as functional food and natural medicine. To characterize the fruit developmental molecular phenotypes, we comprehensively analyzed metabolite composition of both Lycium fruits at three developmental stages using the combined NMR, liquid chromatography-tandem mass spectrometry, and gas chromatography-flame ionization detector/mass spectrometry methods. The metabonomes of these fruits were dominated by over 90 metabolites including sugars, amino acids, tricarboxylic acid (TCA) cycle intermediates, fatty acids, choline metabolites, and shikimate-mediated plant secondary metabolites. Metabolic phenotypes of two species differed significantly at all three developmental stages; LB fruits contained significantly more sugars and amino acids but less TCA cycle intermediates, fatty acids, and secondary metabolites than LR. Interspecies differences for fatty acid levels were much greater after color-breaking than precolor-breaking. Furthermore, LR fruits contained more osmolytes than LB fruits indicating different osmoregulation requirements for these fruits during development. Significant differences were also present in biosynthesis of shikimate-mediated plant secondary metabolites in LR and LB. These findings provided essential metabolic information for plant physiology of these  Lycium species and their utilizations demonstrating the usefulness of this metabonomic phenotyping approach for studying fundamental biochemistry of the plant development.

Dynamic metabolic responses of brown planthoppers towards susceptible and resistant rice plants.

Brown planthopper (Nilaparvata lugens Stål, BPH) causes huge economic losses in rice-growing regions, and new strategies for combating BPH are required. To understand how BPHs respond towards BPH-resistant plants, we systematically analysed the metabolic differences between BPHs feeding on the resistant and susceptible plants using NMR and GC-FID/MS. We also measured the expression of some related genes involving glycolysis and biosyntheses of trehalose, amino acids, chitin and fatty acids using real-time PCR. BPH metabonome was dominated by more than 60 metabolites including fatty acids, amino acids, carbohydrates, nucleosides/nucleotides and TCA cycle intermediates. After initial 12 h, BPHs feeding on the resistant plants had lower levels of amino acids, glucose, fatty acids and TCA cycle intermediates than on the susceptible ones. The levels of these metabolites recovered after 24 h feeding. This accompanied with increased level in trehalose, choline metabolites and nucleosides/nucleotides compared with BPH feeding on the susceptible plants. Decreased levels of BPH metabolites at the early feeding probably resulted from less BPH uptakes of sap from resistant plants and recovery of BPH metabolites at the later stage probably resulted from their adaptation to the adverse environment with their increased hopping frequency to ingest more sap together with contributions from yeast-like symbionts in BPHs. Throughout 96 h, BPH feeding on the resistant plants showed significant up-regulation of chitin synthase catalysing biosynthesis of chitin for insect exoskeleton, peritrophic membrane lining gut and tracheae. These findings provided useful metabolic information for understanding the BPH-rice interactions and perhaps for developing new BPH-combating strategies.

Metabonomic Changes Associated with Atherosclerosis Progression for LDLR(-/-) Mice.

Atherosclerosis resulting from hyperlipidemia causes many serious cardiovascular diseases. To understand the systems changes associated with pathogenesis and progression of atherosclerosis, we comprehensively analyzed the dynamic metabonomic changes in multiple biological matrices of LDLR(-/-) mice using NMR and GC-FID/MS with gene expression, clinical chemistry, and histopathological data as well. We found that 12 week "Western-type" diet (WD) treatment caused obvious aortic lesions, macrophage infiltration, and collagen level elevation in LDLR(-/-) mice accompanied by up-regulation of inflammatory factors including aortic ICAM-1, MCP-1, iNOS, MMP2, and hepatic TNFα and IL-1ß. The WD-induced atherosclerosis progression was accompanied by metabonomic changes in multiple matrices including biofluids (plasma, urine) and (liver, kidney, myocardial) tissues involving multiple metabolic pathways. These included disruption of cholesterol homeostasis, disturbance of biosynthesis of amino acids and proteins, altered gut microbiota functions together with metabolisms of vitamin-B3, choline, purines, and pyrimidines. WD treatment caused down-regulation of SCD1 and promoted oxidative stress reflected by urinary allantoin elevation and decreases in hepatic PUFA-to-MUFA ratio. When switching to normal diet, atherosclerotic LDLR(-/-) mice reprogrammed their metabolisms and reversed the atherosclerosis-associated metabonomic changes to a large extent, although aortic lesions, inflammation parameters, macrophage infiltration, and collagen content were only partially alleviated. We concluded that metabolisms of fatty acids and vitamin-B3 together with gut microbiota played crucially important roles in atherosclerosis development. These findings offered essential biochemistry details of the diet-induced atherosclerosis and demonstrated effectiveness of the integrated metabonomic analysis of multiple biological matrices for understanding the molecular aspects of cardiovascular diseases.

Systemic responses of BALB/c mice to Salmonella typhimurium infection.

Salmonella typhimurium is a bacterial pathogen that poses a great threat to humans and animals. In order to discover hosts' responses to S. typhimurium infection, we collected and analyzed biofluids and organ tissues from mice which had ingested S. typhimurium. We employed (1)H NMR spectroscopy coupled with multivariate data analysis and immunological techniques. The results indicate that infection leads to a severe impact on mice spleen and ileum, which are characterized by splenomegaly and edematous villi, respectively. We found that increased levels of itaconic acid were correlated with the presence of splenomegaly during infection and may play an important role in Salmonella-containing vacuole acidification. In addition, metabonomic analyses of urine displayed the development of salmonellosis in mice, which is characterized by dynamic changes in energy metabolism. Furthermore, we found that the presence of S. typhimurium activated an anti-oxidative response in infected mice. We also observed changes in the gut microbial co-metabolites (hippurate, TMAO, TMA, methylamine). This investigation sheds much needed light on the host-pathogen interactions of S. typhimurium, providing further information to deepen our understanding of the long co-evolution process between hosts and infective bacteria.

Microbial Tryptophan Metabolites Ameliorate Ovariectomy-Induced Bone Loss by Repairing Intestinal AhR-Mediated Gut-Bone Signaling Pathway.

Microbial tryptophan (Trp) metabolites acting as aryl hydrocarbon receptor (AhR) ligands are shown to effectively improve metabolic diseases via regulating microbial community. However, the underlying mechanisms by which Trp metabolites ameliorate bone loss via gut-bone crosstalk are largely unknown. In this study, supplementation with Trp metabolites, indole acetic acid (IAA), and indole-3-propionic acid (IPA), markedly ameliorate bone loss by repairing intestinal barrier integrity in ovariectomy (OVX)-induced postmenopausal osteoporosis mice in an AhR-dependent manner. Mechanistically, intestinal AhR activation by Trp metabolites, especially IAA, effectively repairs intestinal barrier function by stimulating Wnt/ß-catenin signaling pathway. Consequently, enhanced M2 macrophage by supplementation with IAA and IPA secrete large amount of IL-10 that expands from intestinal lamina propria to bone marrow, thereby simultaneously promoting osteoblastogenesis and inhibiting osteoclastogenesis in vivo and in vitro. Interestingly, supplementation with Trp metabolites exhibit negligible ameliorative effects on both gut homeostasis and bone loss of OVX mice with intestinal AhR knockout (VillinCreAhrfl/fl). These findings suggest that microbial Trp metabolites may be potential therapeutic candidates against osteoporosis via regulating AhR-mediated gut-bone axis.

Microbiome-gut-brain axis contributes to patients and Bama miniature pigs with acute large ischemic stroke.

Acute large hemispheric infarction (ALHI) is an overwhelming emergency with a great challenge of gastrointestinal dysfunction clinically. Here, we initially proposed delayed bowel movements as the clinical phenotype of strike to gut-brain axis (GBA) in ALHI patients by epidemiological analysis of 499 acute ischemic stroke (AIS) patients. 1H NMR-based metabolomics revealed that AIS markedly altered plasma global metabolic profiling of patients compared with healthy controls. Risk factors of strike on GBA were the National Institutes of Health Stroke Scale (NIHSS) score ≥ 5 and stroke onset time ≤ 24 h. As a result, first defecating time after admission to the hospital ≥2 days could be considered as a potential risk factor for strike on GBA. Subsequently, the ALHI Bama miniature (BM) pig model with acute symptomatic seizure was successfully established by ligation of the left ascending pharyngeal artery combined with local air injection. Clinical phenotypes of brain necrosis such as hemiplegia were examined with brain diffusion-weighted imaging (DWI) and pathological diagnosis. In addition to global brain injury and inflammation, we also found that ALHI induced marked alterations of intestinal barrier integrity, the gut microbial community, and microbiota-derived metabolites including serotonin and neurotransmitters in both plasma and multiple brain tissues of BM pigs. These findings revealed that microbiota-gut-brain axis highly contributed to the occurrence and development of ALHI.

Metabolic influence of acute cyadox exposure on Kunming mice.

Cyadox is an antibiotic drug and has the potential to be used as a feedstuff additive in promoting the growth of animals. However, the toxicity of cyadox should be fully assessed before application, and this has prompted the current investigation on the metabolic responses of mice to cyadox exposure, using a metabonomic technique. Three groups of Kunming mice were respectively given a single dose of cyadox at three different concentrations (100, 650, and 4000 mg/kg body weight) via gavage. We present here the metabolic alterations of urine, plasma, liver, and renal medulla extracts induced by cyadox exposure. The metabolic alterations induced by cyadox exposure are dose-dependent, and metabolic recovery is achieved only for low and moderate levels of cyadox exposure during the experimental period. Cyadox exposure resulted in a disturbance of gut microbiota, which is manifested in depleted levels of urinary hippurate, trimethylamine-N-oxide (TMAO), dimethylamine (DMA), and trimethylamine (TMA). In addition, mice exposed to cyadox at high levels caused accumulations of amino acids and depletions of nucleotides in the liver. Furthermore, marked elevations of nucleotides and a range of organic osmolytes, such as myo-inositol, choline, and glycerophosphocholine (GPC), and decreased levels of amino acids are observed in the renal medulla of cyadox-exposed mice. These results suggest that cyadox exposure causes inhibition of amino acid metabolism in the liver and disturbance of gut microbiota community, influencing osmolytic homeostasis and nucleic acids synthesis in both the liver and the kidney. Our work provides a comprehensive view of the toxicological effects of cyadox, which is important in animal and human food safety.

Combined NMR and GC-MS analyses revealed dynamic metabolic changes associated with the carrageenan-induced rat pleurisy.

Inflammation is closely associated with pathogenesis of various metabolic disorders, cardiovascular diseases, and cancers. To understand the systems responses to localized inflammation, we analyzed the dynamic metabolic changes in rat plasma and urine associated with the carrageenan-induced self-limiting pleurisy using NMR spectroscopy in conjunction with multivariate data analysis. Fatty acids in plasma were also analyzed using GC-FID/MS with the data from clinical chemistry and histopathology as complementary information. We found that in the acute phase of inflammation rats with pleurisy had significantly lower levels in serum albumin, fatty acids, and lipoproteins but higher globulin level and larger quantity of pleural exudate than controls. The carrageenan-induced inflammation was accompanied by significant metabolic alterations involving TCA cycle, glycolysis, biosyntheses of acute phase proteins, and metabolisms of amino acids, fatty acids, ketone bodies, and choline in acute phase. The resolution process of pleurisy was heterogeneous, and two subgroups were observed for the inflammatory rats at day-6 post treatment with different metabolic features together with the quantity of pleural exudate and weights of thymus and spleen. The metabolic differences between these subgroups were reflected in the levels of albumin and acute-phase proteins, the degree of returning to normality for multiple metabolic pathways including glycolysis, TCA cycle, gut microbiota functions, and metabolisms of lipids, choline and vitamin B3. These findings provided some essential details for the dynamic metabolic changes associated with the carrageenan-induced self-limiting inflammation and demonstrated the combined NMR and GC-FID/MS analysis as a powerful approach for understanding biochemical aspects of inflammation.

High-fat diet induces dynamic metabolic alterations in multiple biological matrices of rats.

Obesity is a condition resulting from the interactions of individual biology and environmental factors causing multiple complications. To understand the system's metabolic changes associated with the obesity development and progression, we systematically analyzed the dynamic metabonomic changes induced by a high-fat diet (HFD) in multiple biological matrices of rats using NMR and GC-FID/MS techniques. Clinical chemistry and histopathological data were obtained as complementary information. We found that HFD intakes caused systematic metabolic changes in blood plasma, liver, and urine samples involving multiple metabolic pathways including glycolysis, TCA cycle, and gut microbiota functions together with the metabolisms of fatty acids, amino acids, choline, B-vitamins, purines, and pyrimidines. The HFD-induced metabolic variations were detectable in rat urine a week after HFD intake and showed clear dependence on the intake duration. B-vitamins and gut microbiota played important roles in the obesity development and progression together with changes in TCA cycle intermediates (citrate, α-ketoglutarate, succinate, and fumarate). 83-day HFD intakes caused significant metabolic alterations in rat liver highlighted with the enhancements in lipogenesis, lipid accumulation and lipid oxidation, suppression of glycolysis, up-regulation of gluconeogenesis and glycogenesis together with altered metabolisms of choline, amino acids and nucleotides. HFD intakes reduced the PUFA-to-MUFA ratio in both plasma and liver, indicating the HFD-induced oxidative stress. These findings provided essential biochemistry information about the dynamic metabolic responses to the development and progression of HFD-induced obesity. This study also demonstrated the combined metabonomic analysis of multiple biological matrices as a powerful approach for understanding the molecular basis of pathogenesis and disease progression.

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.

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.

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.

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.

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.