Ophiopogon japonicuspolysaccharides (OJP) commonly used as functional food additives have been known to have various pharmacological activities. However, the exact roles of OJP in treating ulcerative colitis (UC) remain unknown. Here, we found that oral administration of OJP at different dosages effectively alleviated colonic injury and restored intestinal homeostasis in UC mice in a gut microbiota-dependent manner. Notably, the OJP treatment markedly improved the gut dysbiosis by enriching probiotics, especiallyLactobacillus salivarius, and triggering the production of chenodeoxycholic acid (CDCA), a primary bile acid with controversial biological function. Supplementation with both CDCA andL. salivariuscan significantly repair gut barrier dysfunction and alleviate intestinal inflammation in DSS-induced UC mice. Mechanistically, CDCA treatment strikingly inhibited the STING1-related NF-κB pathway in UC mice probably by binding to STING1, thus strongly suppressing colonic inflammatory status. These results suggest that OJP has potential preventive or therapeutic effects for inflammatory diseases.

Microbial networks and keystone taxa play pivotal roles in maintaining gut microecological stability and host homeostasis, irrespective of their abundance. However, most previous studies of aging-associated gut microbiota have relied on abundance-based analyses, largely overlooking microbial networks and microbe-host interactions. Here, we employed a co-occurrence network approach to identify keystone taxa during aging in humans and mice. We found that centenarians harbor distinctive keystone taxa dominated by members of Clostridium, of which Clostridium scindens (C. scindens) can significantly enhance microbial network stability, probably contributing to longevity and reduced susceptibility to age-related diseases. Mechanistically, C. scindens produces indole-3-acetic acid (IAA) from tryptophan via the enzymes amidase (AMIE) and aldehyde dehydrogenase (ALDH). Oral administration of either C. scindens or IAA effectively mitigates intestinal aging by restoring gut barrier dysfunction in aged mice. Further analysis revealed that C. scindens-derived IAA restores intestinal dysfunction through activation of aryl hydrocarbon receptor (AHR) signaling, leading to upregulation of intestinal CLDN10, a key tight junction protein. Structurally, IAA enhances Claudin-10 transcription by promoting AHR binding to its promoter region. Our findings provide new insights into the characterization of microbial networks in centenarians and highlight that C. scindens and IAA may contribute to healthy longevity by promoting gut microecological stability and host homeostasis.

Background:Ceramide, acting as an important second messenger, plays a pivotal role in the induction of apoptosis in cancer cells. As one of the active prenylflavonoid ingredients in Epimedium, icariside I (GH01) has been shown to exhibit significant anticancer activity. However, the mechanism by which GH01 induces tumor cell apoptosis by targeting ceramide-orchestrated signaling remains unclear. Purpose:This study aimed to analyze the potential mechanism of GH01 for cancer therapy by generating ceramide formation in vivo and in vitro. Methods:A B16F10 melanoma-bearing mouse model was first established and treated with GH01 at different doses. Targeted quantification of ceramide was performed in vivo and in vitro using HPLC-QQQ-MS. A series of biological assays coupled with immunofluorescence staining and confocal microscope were utilized to analyze the apoptotic mechanism of tumor cells. Results:GH01 treatment markedly enhanced ceramide levels through the activation of ceramide de novo synthesis and sphingomyelin hydrolysis pathways coupled with the simultaneous suppression of sphingosine 1-phosphate generation. Consequently, high levels of ceramide promoted tumor cell apoptosis via both intrinsic and extrinsic apoptosis pathways. Notably, ceramide induced by GH01 interacted with mitochondria, thus releasing cytochrome c, which in turn activated caspase-9 and caspase-3, ultimately triggering cellular apoptosis. Additionally, the supplementation of inhibitors of caspase-3 and exogenous ceramide further confirmed the above apoptosis mechanism.

Disruption of aryl hydrocarbon receptor (AhR) signaling and aberrant tryptophan metabolism have been shown to be highly associated with aging and age-related disorders. However, the underlying molecular mechanisms by which the AhR-mediated signaling pathway contributes to the aging process remain largely unknown. In this study, we find that aged Drosophila exhibits markedly reduced tryptophan metabolism leading to impaired AhR ligands, especially indole acetic acid (IAA), compared with their young controls. Supplementation with IAA, produced from Lactobacillus spp., dose-dependently extends the lifespan of Drosophila and improves healthy aging with resistance to starvation and oxidative stress. Mechanistically, activation of AhR by IAA markedly enhances Sirt2 activity by binding to its promoter, thereby inhibiting downstream TOR signaling and related fatty acid and amino acid metabolism. Both Ahr and Sirt2 mutant flies with IAA supplementation display a negligible lifespan extension, suggesting that AhR-mediated Sirt2 signaling contributes to lifespan extension in flies upon IAA supplementation. From the perspective of host metabolism, IAA supplementation significantly increases unsaturated fatty acids (UFAs) in aged flies, which are regarded to be beneficial for healthy status. These findings provide new insights into the physiological functions of AhR involved in the aging process by mediating Sirt2 signaling. IMPORTANCE:Disruption of aryl hydrocarbon receptor (AhR) signaling and aberrant tryptophan metabolism contribute to aging and age-related disorders, but the underlying molecular mechanisms are largely unknown. Using multiomics analyses combined with biochemical assays, this study reveals that AhR activation by indole acetic acid (IAA) effectively extends the lifespan accompanied by improved healthy aging in Drosophila via the AhR-Sirt2 pathway.

Increasing evidence suggests that the aryl hydrocarbon receptor (AHR) and poly (ADP-ribose) polymerase 1 (PARP1) are closely linked to aging and aging-related disorders. However, the underlying mechanisms of AHR-PARP1 axis-mediated DNA repair in countering aging remain largely unknown. In this study, it is found that both aged humans and mice exhibit marked intestinal aging, characterized by gut dysbiosis and dysfunction and DNA damage, compared to their young counterparts. Intriguingly, it is discovered that intestinal AHR activation by indole-3-acetic acid (IAA), which is derived from Lactobacillus salivarius rather than host cells, effectively mitigates intestinal aging by regulating DNA-damage responses. Mechanistically, activated AHR by IAA interacts with PARP1, potentiating PARP1 activity and the polymerization of poly (ADP-ribose) (PARylation) by binding to its promoter. This interaction enhances intestinal barrier function and suppresses inflammation and cell senescence. Finally, the interplay between AHR and PARP1 is confirmed by in vivo and in vitro experiments, including intestine-specific Ahr knockout mice, Ahr and Parp1 knockdown, and Parp1 overexpression in enterocytes. These findings provide a potential intervention strategy targeting AHR-PARP1 axis to mitigate age-related intestinal dysfunction.

Radiotherapy reduces the risk of cancer recurrence and death, but the fact that it's accompanied by multiple side effects including muscle fibrosis and weakness, seriously affects the life quality of patients. However, the underlying mechanism is poorly defined. Here, we identify that cancer cells secrete more spermidine synthase (SRM) enzyme through small extracellular vesicles to trigger skeletal muscle weakness upon radiotherapy. Mechanistically, irradiation-triggered arachidonic acid (ArA) accumulation elevates the ISGylation of the SRM protein, facilitating SRM packaging into extracellular vesicles from the primary tumor. Circulating SRM results in spermidine accumulation in skeletal muscle and type I collagen fiber biosynthesis in an eIF5A-dependent manner. However, losartan treatment blocks the ISGylation of SRM and its subsequent secretion. Collectively, our findings determine that ArA functions in concert for circulating SRM secretion upon radiotherapy, which aggravates skeletal muscle fibrosis through rewiring polyamine metabolism, shedding light on the alleviation of radiotherapy-mediated muscle weakness when combined with losartan treatment.

Sacha inchi (SI, Plukenetia volubilis L.) is a South American oleaginous crop with multiple health benefits and has been traditionally used to treat various ailments due to its bioactive ingredients such as polyphenols and flavonoids. In this study, a variety of compounds including three flavonoids (epigallocatechin, luteolin-3′,7-di-O-glucoside and cosmosiin), two polyphenols (gallic acid and 4-hydroxycoumarin) and three organic acids (malic acid, citric acid and 2-isopropylmalic acid) were firstly identified by UHPLC-QQQ-MS. Subsequently, in vitro results show that SI leaf aqueous extract (SILE) exhibit potential to lower uric acid (UA) by affecting mRNA levels of UA synthases (XO and HGPRT) with neglectable impacts on cell viability of liver cells (L02). In vivo experiments further suggest that SILE can effectively reduce the levels of serum UA and renal inflammatory cytokines (Il-1β, Il-6 and Tnf-α), and improve renal function indicators (serum Cr and BUN), thereby repairing kidney injury in both acute and chronic hyperuricemic (HUA) animal models. In addition, SILE also improve UA metabolism by inhibiting UA biosynthesis and reabsorption and promoting UA excretion. 1H NMR-based metabolomics reveals that SILE effectively regulate the levels of glucose, amino acid, purine and pyrimidine that are involved in UA metabolic pathway in kidney of HUA mice. These findings demonstrate that SILE rich in polyphenols and flavonoids has a great potential for HUA treatment by inhibiting xanthine oxidase activity and improving UA metabolism.

Cancer cells secrete extracellular vesicles (EV) encapsulating bioactive cargoes to facilitate inter-organ communication in vivo and are emerging as critical mediators of tumor progression and metastasis, a condition which is often accompanied by a dysregulated cholesterol metabolism. Whether EVs are involved in the control of cholesterol homeostasis during tumor metastasis is still undefined and warrant further investigation. Here, we find that breast cancer-derived exosomal miR-9-5p induces the expression of HMGCR and CH25H, two enzymes involved in cholesterol synthesis and the conversion of 25-hydroxycholesterol from cholesterol by targeting INSIG1, INSIG2 and ATF3 genes in the liver. Notably, in vivo miR-9-5p antagomir treatment and genetic CH25H ablation prevents tumor metastasis in a mouse model of breast cancer. Thus, our findings reveal the regulatory mechanism of tumor-derived miR-9-5p in liver metastasis by linking oxysterol metabolism and Kupffer cell polarization, shedding light on future applications for cancer diagnosis and treatment.

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-1β, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

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/β-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.

The human gutGut is regarded as a metabolic “super organ” populated by millions of microorganisms and functions as a dynamic barrier to the environment with signal integration properties. Increasing evidence has shown that the gutGut microbiotaGut microbiota and its metabolites are highly associated with many physiological processes, including nutrient intake, growth, and development as well as immune and inflammatoryInflammatory status. It is well known that ageingAgeing is a biological and psychological process with progressive decline in host functional homeostasis. Furthermore, ageingAgeing is one of the biggest risk factors for many metabolic syndromes such as osteoporosis, cancer, and neurodegenerative pathologies, which negatively impact human vitality, healthspan, and lifespan. Thus, it can be seen that the gutGut microbiotaGut microbiota and its metabolites are guaranteed to be responsible for ageingAgeing andAgeing ageing-related diseases. This chapter highlights the roles of intestinal barrier functionsIntestinal barrier function, the gutGut microbiota,Gut microbiota and microbiota-derived metabolites mainly including short chain fatty acids (SCFAs)Short Chain Fatty Acids (SCFAs), bile acids (BAs),Bile Acids (BAs) and tryptophanTryptophan metabolites in ageingAgeing and ageing-related chronic diseases.

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.

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.

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.

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.

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.

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.

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.

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.

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.