Cell metabolomics reveals the neurotoxicity mechanism of cadmium in PC12 cells

Hexavalent chromium reduces testosterone levels by impairing lipophagy and disrupting lipid metabolism homeostasis: Based on a metabolomic analysis

Hexavalent chromium (Cr(VI)) causes testicular damage and reduces testosterone secretion. Testosterone synthesis relies on cholesterol as a raw material, and its availability can be affected by lipophagy. However, the role of lipophagy in Cr(VI)-induced testicular damage and reduced testosterone secretion remains unclear. In this study, we investigated the effect of Cr(VI) on lipid metabolism and lipophagy in the testes of ICR mice. Forty mice were randomly divided into four groups and exposed to different doses of Cr(VI) (0, 75, 100, 125 mg/kg) for thirty days. Cr(VI) increased the rate of sperm abnormalities, decreased testosterone level, and decreased the levels of testosterone synthesis-related proteins, namely steroidogenic acute regulatory (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD) proteins. Through metabolomic analysis, Oil Red O staining, and biochemical indicator (triglyceride and total cholesterol) analysis, Cr(VI) was found to disrupt testicular lipid metabolism. Further investigation revealed that Cr(VI) inhibited the AMP-activated protein kinase (AMPK)/sterol regulatory element-binding protein 1 (SREBP1) pathway, elevated levels of the autophagy-related proteins microtubule-associated protein 1 light chain 3B (LC3B) and sequestosome 1 (SQSTM1)/P62 and lipophagy-related proteins Rab7 and Rab10, while increasing colocalization of LC3B and Perilipin2. These findings suggest that Cr(VI) exposure leads to abnormal lipid metabolism in the testes by suppressing the AMPK/SREBP1 pathway and disrupting lipophagy, ultimately reducing testosterone level and inducing testicular damage.

Extraction and characterization of hepatoprotective polysaccharides from Anoectochilus roxburghii against CCl4-induced liver injury via regulating lipid metabolism and the gut microbiota

Anoectochilus roxburghii polysaccharides exhibit notable hepatoprotective effects, but the underlying substance basis and mechanisms remain unknown. In this study, four new polysaccharides named ARP-1a, ARP-1b, ARP-2a and ARP-2b, were isolated from A. roxburghii. Their structural characteristics were systematically analyzed using HPGPC, HPLC, GC-MS, IR and NMR analysis. ARP-1a, the leading polysaccharide isolated from A. roxburghii, was further evaluated for its hepatoprotective effects on acute liver injury mice induced by CCl4. ARP-1a significantly reduced the serum ALT, AST, TNF-α, IL-1β and IL-6 levels, liver MDA content, and increased the SOD and CAT activities and GSH level in liver. H&E staining revealed that ARP-1a pretreatment could markedly relieve liver injury. Further mechanism exploration indicated that ARP-1a could relieve CCl4-induced oxidative damage through activating the Nrf2 signaling. In addition, metabolomics, lipidomics and 16S rRNA amplicon sequencing were used to elucidate the underlying mechanisms of ARP-1a. Multi-omics analysis indicated that ARP-1a exerted hepatoprotective effect against CCl4-induced acute liver injury by regulating lipid metabolism and modulating the gut microbiota. In conclusion, the above results suggest that ARP-1a can be considered a promising and safe candidate for hepatoprotective drug, as well as a potential prebiotic for maintaining intestinal homeostasis and promoting human intestinal health.

Naringenin Against Cadmium Toxicity in Fibroblast Cells: An Integrated Network Pharmacology and In Vitro Metabolomics Approach

Cadmium, a heavy metal, disrupts cellular homeostasis and is highly toxic, with no effective treatments currently available against its toxicity. According to studies, phytochemicals provide a promising strategy for mitigating cadmium toxicity. Naringenin (NG), a potent antioxidant found primarily in citrus fruits, showed protective properties against cadmium toxicity in rats. Nonetheless, the precise mechanism of cadmium cytotoxicity in fibroblasts remains unknown. This study evaluated NG against cadmium (CdCl2) toxicity utilizing network pharmacology and in silico molecular docking, and was further validated experimentally in rat fibroblast F111 cells. Using network pharmacology, 25 possible targets, including the top 10 targets of NG against cadmium, were identified. Molecular docking of interleukin 6 (IL6), the top potential target with NG, showed robust binding with an inhibition constant (Ki) of 58.76 μM, supporting its potential therapeutic potential. Pathway enrichment analysis suggested that "response to reactive oxygen species" and "negative regulation of small molecules metabolic process" were the topmost pathways targeted by NG against cadmium. In vitro analysis showed that NG (10 μM) attenuated CdCl2-induced oxidative stress by reducing altered intracellular ROS, mitochondrial mass, and membrane potential. Also, NG reversed CdCl2-mediated nuclear damage, G2/M phase arrest, and apoptosis. GC/MS-based metabolomics of F111 cells revealed CdCl2 reduced cholesterol levels, which led to alterations in primary bile acid, steroid and steroid hormone biosynthesis pathways, whereas, NG restored these alterations. In summary, combined in silico and in vitro analysis suggested that NG protected cells from CdCl2 toxicity by mitigating oxidative stress and metabolic pathway alterations, providing a comprehensive understanding of its protective mechanisms against cadmium-induced toxicity.

Transcriptome response of a marine copepod in response to environmentally-relevant concentrations of saxitoxin

Paralytic shellfish toxins (PSTs) can pose a serious threat to human health. Among them, saxitoxin (STX) is one of the most potent natural neurotoxins. Here, the copepod Tigriopus japonicus, was exposed to environmentally relevant concentrations (2.5 and 25 μg/L) STX for 48 h. Although no lethal effects were observed at both concentrations, the transcriptome was significantly altered, and displayed a concentration-dependent response. STX exposure decreased the copepod's metabolism and compromised immune defense and detoxification. Additionally, STX disturbed signal transduction, which might affect other cellular processes. STX exposure could inhibit the copepod's chitin metabolism, disrupting its molting process. Also, the processes related to damage repair and protection were up-regulated to fight against high concentration exposure. Collectively, this study has provided an early warning of PSTs for coastal ecosystem not only because of their potent toxicity effect but also their bioaccumulation that can transfer up the food chain after ingestion by copepods.

Ecotoxicological impact of naproxen on Eisenia fetida: Unraveling soil contamination risks and the modulating role of microplastics

Soils represent crucial sinks for pharmaceuticals and microplastics, making them hotspots for pharmaceuticals and plastic pollution. Despite extensive research on the toxicity of pharmaceuticals and microplastics individually, there is limited understanding of their combined effects on soil biota. This study focused on the earthworm Eisenia fetida as test organism to evaluate the biotoxicity and bioaccumulation of the typical pharmaceutical naproxen and microplastics in earthworms. Results demonstrated that high concentrations of naproxen (100 mg kg-1) significantly increased the malondialdehyde (MDA) content, inducing lipid peroxidation. Even though the low exposure of naproxen exhibits no significant influence to Eisenia fetida, the lipid peroxidation caused by higher concentration than environmental relevant concentrations necessitate attention due to temporal and spatial concentration variability found in the soil environment. Meanwhile, microplastics caused oxidative damage to antioxidant enzymes by reducing the superoxide dismutase (SOD) activity and MDA content in earthworms. Metabolome analysis revealed increased lipid metabolism in naproxen-treated group and reduced lipid metabolism in the microplastic-treated group. The co-exposure of naproxen and microplastics exhibited a similar changing trend to the microplastics-treated group, emphasizing the significant influence of microplastics. The detection of numerous including lipids like 17-Hydroxyandrostane-3-glucuronide, lubiprostone, morroniside, and phosphorylcholine, serves to identify potential biomarkers for naproxen and microplastics exposure. Additionally, microplastics increased the concentration of naproxen in earthworms at sub-organ and subcellular level. This study contributes valuable insights into the biotoxicity and distribution of naproxen and microplastics in earthworms, enhancing our understanding of their combined ecological risk to soil biota.

Heavy metal exposure and metabolomics analysis: an emerging frontier in environmental health

Exposure to heavy metals in various populations can lead to extensive damage to different organs, as these metals infiltrate and bioaccumulate in the human body, causing metabolic disruptions in various organs. To comprehensively understand the metal homeostasis, inter-organ "traffic," and extensive metabolic alterations resulting from heavy metal exposure, employing complementary analytical methods is crucial. Metabolomics is pivotal in unraveling the intricacies of disease vulnerability by furnishing thorough understandings of metabolic changes linked to different metabolic diseases. This field offers exciting prospects for enhancing the disease prevention, early detection, and tailoring treatment approaches to individual needs. This article consolidates the existing knowledge on disease-linked metabolic pathways affected by the exposure of diverse heavy metals providing concise overview of the underlying impact mechanisms. The main aim is to investigate the connection between the altered metabolic pathways and long-term complex health conditions induced by heavy metals such as diabetes mellitus, cardiovascular diseases, renal disorders, inflammation, neurodegenerative diseases, reproductive risks, and organ damage. Further exploration of common pathways may unveil the shared targets for treating associated pathological conditions. In this article, the role of metabolomics in disease susceptibility is emphasized that metabolomics is expected to be routinely utilized for the diagnosis and monitoring of diseases and practical value of biomarkers derived from metabolomics, as well as determining their appropriate integration into extensive clinical settings.

Metabolomic changes in culture media with varying passage numbers of pig muscle stem cell culture for cultured meat production

Selecting the primary cells in an optimal state for cultured meat production is a crucial challenge in commercializing cultured meat. We investigated the metabolomic changes in culture media according to passage numbers for indirectly assessing the state of primary cells. Pig skeletal muscle stem cells (PSCs) harvested from the biceps femoris muscles of 7-d-old crossbred pigs (Landrace × Yorkshire × Duroc, LYD) were used for cell characterization. Fresh media (FM) and spent media (SM) of PSCs during passages 1 to 3 in vitro culture were prepared for metabolomics analysis. SM was collected on the third day of proliferation for each passage of PSCs. Cell characterization analysis revealed that the proliferation rate was highest at passage 2; however, a significant loss of expression of myogenic marker genes was observed at passage 3. Based on metabolomic profiles of culture media, FM and SM groups (SM1, SM2, and SM3) were clearly separated by partial least squares-discriminant analysis. A total of seven differentially abundant metabolites (DAMs) were identified from FM and SM for each passage, based on the following criteria: P < 0.05, fold change > 1.5 or < 0.66, and a variable importance in projection score > 1.5. All seven DAMs and their interconnected metabolites might be primarily used as substrates for energy production and most of them were relatively abundant in SM3. Among the seven DAMs, the three potential biomarkers (γ-glutamyl-L-leucine, cytosine, and ketoleucine), which showed significant changes exclusively in SM3, each had an area under the curve value of 1. Therefore, monitoring the levels of these key metabolites in culture media could serve as a quality control measure for cultured meat production by enabling the indirect detection of suboptimal PSCs based on their proliferation ability.

Measurements of cadmium levels in relation to tobacco dependence and as a function of cytisine administration

Cigarette smoking delivers a number of heavy metals, including cadmium (Cd), into the body. Bioaccumulation may result in an increase in pathological consequences over time. The assessment of changes in serum Cd concentrations during the treatment of cigarette dependence with cytisine was performed for the first time. Parameters assessing smoking habits, strength of addiction, and effectiveness of therapy were analyzed. Cd was determined before, during, and after the end of treatment. The serum Cd levels were significantly higher in the smokers than in the nonsmokers. Significant differences in Cd concentrations between sampling times in smokers were observed. Individuals who stopped smoking had significantly lower Cd concentrations compared to baseline. A significant positive correlation between the serum Cd before treatment and smoking urges was also obtained. Additionally, salivary Cd determinations were performed before treatment to evaluate the use of this method to assess cigarette addiction. Our findings indicate that Cd can be used as a biomarker of smoking addiction, and provide an alternative assessment of tobacco smoke exposure to other methods. The results provide new knowledge related to Cd concentrations in human body fluids and may play a role in monitoring and assessing the efficacy of cytisine for smoking cessation.

Role of Mitochondrial Reactive Oxygen Species-Mediated Chaperone-Mediated Autophagy and Lipophagy in Baicalin and N-Acetylcysteine Mitigation of Cadmium-Induced Lipid Accumulation in Liver

Cadmium (Cd) is a major health concern globally and can accumulate and cause damage in the liver for which there is no approved treatment. Baicalin and N-acetylcysteine (NAC) have been found to have protective effects against a variety of liver injuries, but it is not clear whether their combined use is effective in preventing and treating Cd-induced lipid accumulation. The study found that Cd increased the production of mitochondrial reactive oxygen species (mROS) and elevated the level of chaperone-mediated autophagy (CMA). Interestingly, mROS-mediated CMA exacerbates the Cd-induced inhibition of lipophagy. Baicalin and NAC counteracted inhibition of lipophagy by attenuating Cd-induced CMA, suggesting an interplay between CMA elevation, mitochondrial destruction, and mROS formation. Maintaining the stability of mitochondrial structure and function is essential for alleviating Cd-induced lipid accumulation in the liver. Choline is an essential component of the mitochondrial membrane and is responsible for maintaining its structure and function. Mitochondrial transcriptional factor A (TFAM) is involved in mitochondrial DNA transcriptional activation and replication. Our study revealed that the combination of baicalin and NAC can regulate choline metabolism through TFAM and thereby maintain mitochondrial structure and functionality. In summary, the combination of baicalin and NAC plays a more beneficial role in alleviating Cd-induced lipid accumulation than the drug alone, and the combination of baicalin and NAC can stabilize mitochondrial structure and function and inhibit mROS-mediated CMA through TFAM-choline, thereby promoting lipophagy to alleviate Cd-induced lipid accumulation.

Untargeted metabolomics reveal pathways associated with neuroprotective effect of oxyresveratrol in SH-SY5Y cells

Oxyresveratrol has been documented benefits for neurodegenerative disease. However, the specific molecular mechanisms and pathways involved is currently limited. This study aimed to investigate the potential neuroprotective mechanisms of oxyresveratrol using rotenone-induced human neuroblastoma SH-SY5Y cytotoxicity. Cells were divided into the following groups: control, rotenone, and oxyresveratrol pre-treated before being exposed to rotenone. Cellular assays were performed to investigate neuroprotective effects of oxyresveratrol. The results showed that 20 μM oxyresveratrol was effective in preventing rotenone-induced cell death and decreasing ROS levels in the cells. The alteration of metabolites and pathways involved in the neuroprotective activities of oxyresveratrol were further investigated using LC-QTOF-MS/MS untargeted metabolomics approach. We hypothesized that oxyresveratrol's neuroprotective effects would be associated with neurodegenerative pathways. A total of 294 metabolites were identified. 7,8-dihydrobiopterin exhibited the highest VIP scores (VIP > 3.0; p < 0.05), thus considered a biomarker in this study. Our results demonstrated that pretreatment with oxyresveratrol upregulated the level of 7,8-dihydrobiopterin compared to the positive control. Pathway analysis verified that 7,8-dihydrobiopterin was primarily associated with phenylalanine, tyrosine, and tryptophan metabolism (impact = 1, p < 0.001), serving as essential cofactors for enzymatic function in the dopamine biosynthesis pathway. In conclusion, oxyresveratrol may be benefit for the prevention of neurodegenerative diseases by increasing 7,8-dihydrobiopterin concentration.

UHPLC-HRMS-based metabolomic and lipidomic characterization of glioma cells in response to anlotinib

Anlotinib, as a promising oral small-molecule antitumor drug, its role in glioma has been only reported in a small number of case reports. Therefore, anlotinib has been considered as a promising candidate in glioma. The aim of this study was to investigate the metabolic network of C6 cells after exposure to anlotinib and to identify anti-glioma mechanism from the perspective of metabolic reprogramming. Firstly, CCK8 method was used to evaluate the effects of anlotinib on cell proliferation and apoptosis. Secondly, ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS)-based metabolomic and lipidomic were developed to characterize the metabolite and lipid changes in cell and cell culture medium (CCM) caused by anlotinib in the treatment of glioma. As a result, anlotinib had concentration-dependent inhibitory effect with the concentration range. In total, twenty-four and twenty-three disturbed metabolites in cell and CCM responsible for the intervention effect of anlotinib were screened and annotated using UHPLC-HRMS. Altogether, seventeen differential lipids in cell were identified between anlotinib exposure and untreated groups. Metabolic pathways, including amino acid metabolism, energy metabolism, ceramide metabolism, and glycerophospholipid metabolism, were modulated by anlotinib in glioma cell. Overall, anlotinib has an effective treatment against the development and progression of glioma, and these remarkable pathways can generate the key molecular events in cells treated with anlotinib. Future research into the mechanisms underlying the metabolic changes is expected to provide new strategies for treating glioma.

The sulfoximine insecticide sulfoxaflor exposure reduces the survival status and disrupts the intestinal metabolism of the honeybee Apis mellifera

Honeybees (Apis mellifera) are indispensable pollinators in agricultural production, biodiversity conservation, and nutrients provision. The abundance and diversity of honeybees have been rapidly diminishing, possibly related to the extensive use of insecticides in ecosystems. Sulfoxaflor is a novel sulfoximine insecticide that, like neonicotinoids, acts as a competitive modulator of nicotinic acetylcholine receptors (nAChR) in insects. However, few studies have addressed the negative effects of sulfoxaflor on honeybees at environmentally relevant concentrations. In the present study, adult workers were fed a 50% (w/v) of sugar solution containing different concentrations (0, 0.05, 0.5 and 2.0 mg/L) of sulfoxaflor for two weeks consecutively. The survival rates, food intake, and body weight of the honeybees significantly decreased after continuous exposure at higher doses (0.5 and 2.0 mg/L) of sulfoxaflor when compared with the control. The change in the metabolites in the honeybee gut was determined using high-throughput non-targeted metabolomics on day 14 after sulfoxaflor treatment. The results revealed that 24 and 105 metabolites changed after exposure to 0.5 and 2.0 mg/L sulfoxaflor, respectively, compared with that of the control groups. A total of 12 changed compounds including pregenolone and glutathione were detected as potential biomarkers, which were eventually found to be enriched in pathways of the steroid hormone biosynthesis (p = 0.0001) and glutathione metabolism (p = 0.021). These findings provide a new perspective on the physiological influence of sulfoxaflor stress in honeybees.

Neurotoxicity mechanism of aconitine in HT22 cells studied by microfluidic chip-mass spectrometry

Aconitine, a common and main toxic component of Aconitum, is toxic to the central nervous system. However, the mechanism of aconitine neurotoxicity is not yet clear. In this work, we had the hypothesis that excitatory amino acids can trigger excitotoxicity as a pointcut to explore the mechanism of neurotoxicity induced by aconitine. HT22 cells were simulated by aconitine and the changes of target cell metabolites were real-time online investigated based on a microfluidic chip-mass spectrometry system. Meanwhile, to confirm the metabolic mechanism of aconitine toxicity on HT22 cells, the levels of lactate dehydrogenase, intracellular Ca²⁺, reactive oxygen species, glutathione and superoxide dismutase, and ratio of Bax/Bcl-2 protein were detected by molecular biotechnology. Integration of the detected results revealed that neurotoxicity induced by aconitine was associated with the process of excitotoxicity caused by glutamic acid and aspartic acid, which was followed by the accumulation of lactic acid and reduction of glucose. The surge of extracellular glutamic acid could further lead to a series of cascade reactions including intracellular Ca²⁺ overload and oxidative stress, and eventually result in cell apoptosis. In general, we illustrated a new mechanism of aconitine neurotoxicity and presented a novel analysis strategy that real-time online monitoring of cell metabolites can provide a new approach to mechanism analysis.

Vitamin E supplementation improves post-transportation systemic antioxidant capacity in yak

This study was aimed to evaluate the effects of post-transportation vitamin E (VE) supplementation on health condition, blood biochemical parameters, blood antioxidant indices and blood metabolomics in yak. Five yaks were used in this study. After 2100 km of highway transportation from Riwoqe county to Rongchang County, Chongqing, blood was collected immediately after arrival and these samples served as the baseline (control, CON_VE). A VE injection (40 mg/kg) was then performed and blood samples were collected 10 days later. Injection of VE led to lower serum VE concentration. Relative to the CON_VE, VE injection led to greater concentrations of creatinine and lower concentrations of glutamate pyruvic transaminase, alkaline phosphatase, aspartate aminotransferase, total bilirubin, indirect bilirubin, direct bilirubin, UREA and glucose. Compared with CON_VE, VE injection led the lower serum level of malondialdehydeand greater serum level of glutathione s-transferase, glutathione peroxidase, glutathione reductase and glutathione peroxidase 4. Based on metabolomics analysis, 119 differentially altered serum metabolites (P<0.05 and VIP>1.0) were identified with VE injection relative to CON_VE. VE injection resulted in changes of lysophosphatidylethanolamine, lysophosphatidylcholine, phosphocholine, choline, malate, citrate, α-Oxo-glutarate, phenylalanine, 3-Phenylpropanoic acid and 3-(3-Hydroxyphenyl) propanoic acid. These metabolites are associated with lipid metabolism, tricarboxylic acid cycle and oxidative stress. Overall, our study indicates that VE injection can alleviate transportation stress in yak partly through protecting liver and kidney, and improving antioxidant defense systems.

Cell Metabolomics Reveals the Potential Mechanism of Aloe Emodin and Emodin Inhibiting Breast Cancer Metastasis

Metastasis is one of the main obstacles for the treatment and prognosis of breast cancer. In this study, the effects and possible mechanisms of aloe emodin (AE) and emodin (EMD) for inhibiting breast cancer metastasis were investigated via cell metabolomics. First, a co-culture model of MCF-7 and HUVEC cells was established and compared with a traditional single culture of MCF-7 cells. The results showed that HUVEC cells could promote the development of cancer cells to a malignant phenotype. Moreover, AE and EMD could inhibit adhesion, invasion, and angiogenesis and induce anoikis of MCF-7 cells in co-culture model. Then, the potential mechanisms behind AE and EMD inhibition of MCF-7 cell metastasis were explored using a metabolomics method based on UPLC-Q-TOF/MS multivariate statistical analysis. Consequently, 27 and 13 biomarkers were identified in AE and EMD groups, respectively, including polyamine metabolism, methionine cycle, TCA cycle, glutathione metabolism, purine metabolism, and aspartate synthesis. The typical metabolites were quantitatively analyzed, and the results showed that the inhibitory effect of AE was significantly better than EMD. All results confirmed that AE and EMD could inhibit metastasis of breast cancer cells through different pathways. Our study provides an overall view of the underlying mechanisms of AE and EMD against breast cancer metastasis.

Landscape of lipidomic metabolites in gut-liver axis of Sprague-Dawley rats after oral exposure to titanium dioxide nanoparticles

Background

The application of titanium dioxide nanoparticles (TiO₂ NPs) as food additives poses a risk of oral exposure that may lead to adverse health effects. Even though the substantial evidence supported liver as the target organ of TiO₂ NPs via oral exposure, the mechanism of liver toxicity remains largely unknown. Since the liver is a key organ for lipid metabolism, this study focused on the landscape of lipidomic metabolites in gut-liver axis of Sprague Dawley (SD) rats exposed to TiO₂ NPs at 0, 2, 10, 50 mg/kg body weight per day for 90 days.

Results

TiO₂ NPs (50 mg/kg) caused slight hepatotoxicity and changed lipidomic signatures of main organs or systems in the gut-liver axis including liver, serum and gut. The cluster profile from the above biological samples all pointed to the same key metabolic pathway and metabolites, which was glycerophospholipid metabolism and Phosphatidylcholines (PCs), respectively. In addition, absolute quantitative lipidomics verified the changes of three PCs concentrations, including PC (16:0/20:1), PC (18:0/18:0) and PC (18:2/20:2) in the serum samples after treatment of TiO₂ NPs (50 mg/kg). The contents of malondialdehyde (MDA) in serum and liver increased significantly, which were positively correlated with most differential lipophilic metabolites.

Conclusions

The gut was presumed to be the original site of oxidative stress and disorder of lipid metabolism, which resulted in hepatotoxicity through the gut-liver axis. Lipid peroxidation may be the initial step of lipid metabolism disorder induced by TiO₂ NPs. Most nanomaterials (NMs) have oxidation induction and antibacterial properties, so the toxic pathway revealed in the present study may be primary and universal.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00484-9.

Integrated Proteomics and Metabolomics Analysis in Pregnant Rat Hippocampus After Circadian Rhythm Inversion

To investigate the changes in proteins, metabolites, and related mechanisms in the hypothalamus of pregnant rats after circadian rhythm inversion during the whole pregnancy cycle. A total of 12 Wistar female rats aged 7 weeks were randomly divided into control (six rats) and experimental (six rats) groups at the beginning of pregnancy. The control group followed a 12-h light and dark cycle (6 a.m. to 6 p.m. light, 6 p.m. to 6 a.m. dark the next day), and the experimental group followed a completely inverted circadian rhythm (6 p.m. to 6 a.m. light the next day, 6 a.m. to 6 p.m. dark). Postpartum data were collected until 7–24 h after delivery, and hypothalamus samples were collected in two groups for quantitative proteomic and metabolism analyses. The differential proteins and metabolites of the two groups were screened by univariate combined with multivariate statistical analyses, and the differential proteins and metabolites enriched pathways were annotated with relevant databases to analyze the potential mechanisms after circadian rhythm inversion. A comparison of postpartum data showed that circadian rhythm inversion can affect the number of offspring and the average weight of offspring in pregnant rats. Compared with the control group, the expression of 20 proteins and 37 metabolites was significantly changed in the experimental group. The integrated analysis between proteins and metabolites found that RGD1562758 and lysophosphatidylcholine acyltransferase 1 (LPCAT1) proteins were closely associated with carbon metabolism (choline, NAD+, L-glutamine, theobromine, D-fructose, and pyruvate) and glycerophospholipid metabolism (choline, NAD+, L-glutamine, phosphatidylcholine, theobromine, D-fructose, pyruvate, and arachidonate). Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differential metabolites enriched in adenosine triphosphate (ATP)–binding cassette (ABC) transporters. Our study suggested that circadian rhythm inversion in pregnant rats may affect the numbers, the average weight of offspring, and the expressions of proteins and metabolism in the hypothalamus, which may provide a comprehensive overview of the molecular profile of circadian rhythm inversion in pregnant groups.

Ambient NO2 exposure induced cardiotoxicity associated with gut microbiome dysregulation and glycerophospholipid metabolism disruption

An average daily increase of 10 μg/m³ in NO₂ concentrations could lead to an increased mortality in cardiovascular, cerebrovascular of 1.89%, 2.07%, but the mechanism by which NO₂ contributes to cardiotoxicity is rarely reported. In order to assess the cardiotoxicity of NO₂ inhalation (5 ppm), we firstly investigate the change of gut microbiota, serum metabonomics and cardiac proteome. Non-targeted LC-MS/MS metabonomics showed that NO₂ stress could perturb the glycerophospholipid metabolism in the serum, which might destabilize the bilayer configuration of cardiac lipid membranes. Furthermore, we observed that NO₂ inhalation caused augmented intercellular gap and inflammatory infiltration in the heart. Although 16 S rRNA gene amplification sequencing demonstrated that NO₂ exposure did not influence the intestinal microbial abundance and diversity, but glycerophospholipid metabolism disruption might be finally reflected in gut microbiom dysregulation, such as Sphingomonas, Koribacter, Actinomarina and Bradyrhizobium Turicibacter, Rothia, Globicatella and Aerococcus. Proteome mining revealed that differentially expressed genes (DEGs) in the heart after NO₂ stress were involved in necroptosis, mitophagy and ferroptosis. We further revealed that NO₂ increased the number of cardiac mitochondria with depletion of cristae by regulating the expression of Mfn2 and Hsp70. This study indicating Mfn2-meidcated imbalanced mitochondrial dynamics as a potential mechanism after NO₂-induced heart injury and suggesting microbiome dysregulation/glycerophospholipid metabolism exerts critical roles in cardiotoxicity caused by NO₂.

Metabolomics as a valid analytical technique in environmental exposure research: application and progress

BACKGROUND

In recent years, studies have shown that exposure to environmental pollutants (e.g., radiation, heavy metal substances, air pollutants, organic pollutants) is a leading cause of human non-communicable diseases. The key to disease prevention is to clarify the harmful mechanisms and toxic effects of environmental pollutants on the body. Metabolomics is a high-sensitivity, high-throughput omics technology that can obtain detailed metabolite information of an organism. It is a crucial tool for gaining a comprehensive understanding of the pathway network regulation mechanism of the organism. Its application is widespread in many research fields such as environmental exposure assessment, medicine, systems biology, and biomarker discovery.

AIM OF REVIEW

Recent findings show that metabolomics can be used to obtain molecular snapshots of organisms after environmental exposure, to help understand the interaction between environmental exposure and organisms, and to identify potential biomarkers and biological mechanisms.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review focuses on the application of metabolomics to understand the biological effects of radiation, heavy metals, air pollution, and persistent organic pollutants exposure, and examines some potential biomarkers and toxicity mechanisms.

Effects of Nongxiangxing baijiu (Chinese liquor) on mild alcoholic liver injury revealed by non-target metabolomics using ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry

Nongxiangxing baijiu (Chinese liquor) is one of the most widely consumed beverages in China. This liquor has been shown to contain large quantities of various bioactive ingredients that are beneficial to health. The goals of the present study were to examine the effects of moderate dose Nongxiangxing baijiu on alcoholic liver injury in rats, and to explore the mechanism of action of Nongxiangxing baijiu on alcoholic liver injury. To accomplish these goals, we developed a metabolomic analysis method based on ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) analysis and multivariate statistical analysis. Our serum lipid and hepatic histopathology results demonstrate that ethanol administration induced mild alcoholic liver injury in rats. However, these ethanol-induced changes were significantly alleviated in the Nongxiangxing baijiu group. These results suggest that moderate dose Nongxiangxing baijiu might have a preventive effect on mild alcoholic liver injury. Using our metabolomics method, we were able to identify 45 differential metabolites in serum and urine which could be used to characterize mild alcoholic liver injury in rats. Of these, 15 differential metabolites, including four Lysophosphatidylethanolamines, two phosphatidylcholines, four long-chain fatty acids, one porphyrin, two esters, one ceramide, and one triol, were regulated by Nongxiangxing baijiu. KEGG metabolic pathway analysis revealed that the main metabolic pathway regulated by Nongxiangxing baijiu was the glycerolipid pathway. Together, these findings provide evidence that moderate dose Nongxiangxing baijiu can reduce mild alcoholic liver injury (including metabolic disorders). Our study also provides preliminary data on the mechanism of action of Nongxiangxing baijiu in liver injury.

Intracellular and extracellular untargeted metabolomics reveal the effect of acute uranium exposure in HK-2 cells

Uranium exposure poses a serious threat to the health of occupational populations and the public. Although metabolomics is a promising research approach to study the toxicological mechanisms of uranium exposure, in vitro studies using human cells are scarce. Applying cultured cell metabolomics, we exhaustively analyzed the intracellular and extracellular differential metabolites upon uranium exposure and characterized the possible biological effects of uranium exposure on human kidney cells. Uranium exposure significantly induced disturbance in the amino acid biosynthesis and linoleic acid metabolism of the cells. Cells exposed to uranium produce excessive amounts of arachidonic acid, which has the potential to cause oxidative stress and damage cells. The results provide new evidence for an oxidative stress mechanism of uranium-induced renal cell injury. Cell metabolomics has proven to be a useful diagnostic tool to study the molecular mechanisms of uranium poisoning.

Baicalin attenuate diet-induced metabolic syndrome by improving abnormal metabolism and gut microbiota

In this work, we examined whether baicalin (BC), a bioactive flavonoid in Scutellaria baicalensis Georgi, can reduce high-fat diet (HFD)-induced metabolic syndrome (MetS) in mice. The UPLC-QTOF/MS was used for metabolome profiles analysis, and an analysis of bacterial 16S rDNA in feces was used to examine the effects of BC on gut microbiota composition. Our results showed that BC (400 mg/kg) could reduce the body weight gain, decrease hepatic fat accumulation and abnormal blood lipids, and increase insulin sensitivity after 8 weeks of treatment. BC could reverse the alteration of 7 metabolites induced by HFD and the metabolic pathways responsive to BC intervention including citrate cycle, alanine, aspartate and glutamate metabolism, glycerophospholipid metabolism, and aminoacyl-tRNA biosynthesis. 16S rDNA analysis demonstrated that BC altered the composition and function of gut microbiota in MetS mice. Notably, we found that the change in succinic acid was negatively associated with the changes in Bacteroides and Sutterella, and positively associated with the change in Mucispirillum. Moreover, we confirmed that succinic acid displayed a metabolic protective effect on MetS mice. The antibiotic treatment verified that BC exerts metabolic protection through gut microbiota. Our findings suggested BC may be a potential therapeutic drug to ameliorate diet induced MetS and gut microbiome may be a novel mechanistic target of BC for treatment of MetS.

Metabolomics Provides Novel Insights into Epilepsy Diagnosis and Treatment: A Review

Epilepsy is one of the most common diseases of the central nervous system. The diagnosis of epilepsy mainly depends on electroencephalograms and symptomatology, while diagnostic biofluid markers are still lacking. In addition, approximately 30% of patients with epilepsy (PWE) show a poor response to the currently available anti-seizure medicines. An increasing number of studies have reported alterations in the blood, brain tissue, cerebrospinal fluid and urine metabolome in PWE and animal models of epilepsy. The aim of this review was to identify potential metabolic biomarkers and pathways that might facilitate diagnostic, therapeutic and prognostic determination in PWE and the understanding of the pathogenesis of the disease. The PubMed and Embase databases were searched for metabolomic studies of PWE and epileptic models published before December 2020. The study objectives, types of models and reported differentially altered metabolites were examined and compared. Pathway analyses were performed using MetaboAnalyst 5.0 online software. Thirty-five studies were included in this review. Metabolites such as glutamate, lactate and citrate were disturbed in both PWE and epileptic models, which might be potential biomarkers of epilepsy. Metabolic pathways including alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism; glycerophospholipid metabolism; glyoxylate and dicarboxylate metabolism; and arginine and proline metabolism were involved in epilepsy. These pathways might play important roles in the pathogenesis of the disease. This review summarizes metabolites and metabolic pathways related to epilepsy and provides a novel perspective for the identification of potential biomarkers and therapeutic targets for epilepsy.

Integration of omics analysis and atmospheric pressure MALDI mass spectrometry imaging reveals the cadmium toxicity on female ICR mouse

Acute cadmium toxicity induces multi-system organ failure. Mass spectrometry (MS)-based omics analyses and atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-MALDI MSI) are powerful tools for characterizing the biomarkers. Many studies on cadmium toxicity by metabolomics have been investigated, whereas the applications of lipidomics and MSI studies are still inadequate. In this study, the systematic metabolomics study on female ICR mice tissues including liver, kidney, heart, stomach, brain as well as spleen under cadmium exposure was firstly conducted and lipidomic characterizations on female ICR mice liver, kidney and heart were further constructed step by step. To deeply understand its toxicological mechanisms, several representative lipids on the mouse liver were visualized by AP-MALDI MSI. The results demonstrated that exposure to cadmium caused significant metabolic alterations in the liver, kidney and heart among all the tissues. Additionally, the toxicological mechanisms of cadmium in the mouse models are closely associated with the inflammation response, energy expenditure, oxidative stress, DNA and mitochondria damage, and lipid homeostasis. These insights could enhance knowledge in acute cadmium toxicity of public health and guide risk assessment in the future.

Exopolysaccharide Produced by Lactiplantibacillus plantarum-12 Alleviates Intestinal Inflammation and Colon Cancer Symptoms by Modulating the Gut Microbiome and Metabolites of C57BL/6 Mice Treated by Azoxymethane/Dextran Sulfate Sodium Salt

Exopolysaccharide produced by Lactiplantibacillus plantarum-12 (LPEPS) exhibited the anti-proliferating effect on human colon cancer cell line HT-29 in vitro. The purpose of the study was to determine the alleviating effects of LPEPS on colon cancer development of the C57BL/6 mice treated by azoxymethane/dextran sulfate sodium salt (AOM/DSS). The C57BL/6 mice treated by AOM/DSS were orally administered LPEPS daily for 85 days. The results showed that LPEPS oral administration enhanced colon tight-junction protein expression and ameliorated colon shortening and tumor burden of the AOM/DSS treated mice. Furthermore, LPEPS oral administration significantly reduced pro-inflammatory factors TNF-α, IL-8, and IL-1β levels and increased anti-inflammatory factor IL-10 level in the serum of the AOM/DSS-treated mice. LPEPS oral administration reversed the alterations of gut flora in AOM/DSS-treated mice, as evidenced by the increasing of the abundance of Bacteroidetes, Bacteroidetes/Firmicutes ratio, Muribaculaceae, Burkholderiaceae, and norank_o__Rhodospirillales and the decreasing of the abundance of Firmicutes, Desulfovibrionaceae, Erysipelotrichaceae, and Helicobacteraceae. The fecal metabolites of the AOM/DSS-treated mice were altered by LPEPS oral administration, involving lipid metabolism and amino acid metabolism. Together, these results suggested that LPEPS oral administration alleviated AOM/DSS-induced colon cancer symptoms of the C57BL/6 mice by modulating gut microbiota and metabolites, enhancing intestine barrier, inhibiting NF-κB pathway, and activating caspase cascade.

Integrated non-targeted lipidomics and metabolomics analyses for fluctuations of neonicotinoids imidacloprid and acetamiprid on Neuro-2a cells

Neonicotinoid insecticides are widely used for pest control. However, they are highly water-soluble and easily ingested by organisms, posing potential health risks. In this study, cytotoxicity evaluations of imidacloprid and acetamiprid were conducted in Neuro-2a cells by obtaining their half maximal inhibitory concentration (IC₅₀ values) (1152.1 and 936.5 μM, respectively). The toxic effects at the IC₁₀ and IC₂₀ on cell metabolism were determined by integrated non-targeted lipidomics and metabolomics analyses. Changes in the concentration of acetamiprid caused the most drastic perturbations of metabolism in Neuro-2a cells. Altogether, the detected lipids were mainly attributed to triglyceride, phosphatidylcholine (PC), and diglyceride. These three categories of lipids accounted for more than 67% of the sum in Neuro-2a cells. A total of 14 lipids and other 40 metabolites were screened as differential metabolites based on multivariate data analysis, and PCs were most frequently observed with a proportion of 25.9%. The results demonstrated that lipid metabolism should be paid considerable attention after imidacloprid and acetamiprid exposure. Pathway analysis showed that the metabolisms of glycerophospholipid, sphingolipid, and glutathione were the dominant pathways that were interfered. The present study is the first to investigate the cellular toxic mechanisms after separate imidacloprid and acetamiprid exposure by using lipidomics and metabolomics simultaneously. This research also provides novel insights into the evaluation of the ecological risk of imidacloprid and acetamiprid and contribute to the study of toxicity mechanism of these neonicotinoid insecticides to animals and humans in the future.

Toxic effects of fipronil and its metabolites on PC12 cell metabolism

Fipronil and its metabolites (fipronil sulfone, fipronil sulfide and fipronil desulfinyl) adversely affect the environment and human health. Targeted metabolomics and lipidomics based on ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to analyse the alterations of glycerophospholipids and amino acids after exposure to fipronil and its metabolites at dosages of 0.5, 12.5 and 50 μM for 72 h and to evaluate their different toxic effects. Results showed that fipronil sulfone and fipronil desulfinyl are more toxic than their parent compound, with fipronil desulfinyl as the most toxic and fipronil sulfide as the least toxic. Fipronil and its metabolites affected the metabolism of PC18:1/16:0, PI18:0/20:4, arginine, leucine and tyrosine and the "phenylalanine, tyrosine and tryptophan biosynthesis" pathway, indicating their possible inducing role in cellular macromolecule damage, nerve signal transmission disturbance and energy metabolism disruption caused by oxidative stress. Importantly, fipronil sulfone and fipronil desulfinyl more strongly influenced lipid and amino acid metabolism, mainly reflected in the number of changed glycerophospholipids and differential metabolites associated with oxidative stress, including PS18:0/20:4, glutamate, phenylalanine and histidine for fipronil sulfone and PS18:0/20:4, glutamate, phenylalanine, serine and aspartic acid for fipronil desulfinyl. Therefore, the higher toxicity of fipronil desulfinyl and fipronil sulfone may be also related to oxidative stress. This study provides implications for risk assessment and toxic mechanism research on fipronil and its metabolites.

Metabolomic Alterations in the Digestive System of the Mantis Shrimp Oratosquilla oratoria Following Short-Term Exposure to Cadmium

Mantis shrimp Oratosquilla oratoria is an economically critical aquatic species along the coast of China but strongly accumulates marine pollutant cadmium (Cd) in its digestive system. It is necessary to characterize the toxicity of Cd in the digestive system of mantis shrimp. The metabolic process is an essential target of Cd toxicity response. In this work, we used ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOF-MS) for untargeted metabolomics to characterize the metabolic changes in the digestive system of O. oratoria, exposed to 0.05 mg/L for 96 h. The aim of this study was to further investigate the effect of O. oratoria on Cd response to toxicity and develop biomarkers. Metabolomics analysis showed the alteration of metabolism in the digestive system of mantis shrimp under Cd stress. A total of 91 metabolites were differentially expressed and their main functions were classified into amino acids, phospholipids, and fatty acid esters. The enrichment results of differential metabolite functional pathways showed that biological processes such as amino acid metabolism, transmembrane transport, energy metabolism, and signal transduction are significantly affected. Based on the above results, the Cd-induced oxidative stress and energy metabolism disorders were characterized by the differential expression of amino acids and ADP in mantis shrimp, while the interference of transmembrane transport and signal transduction was due to the differential expression of phospholipids. Overall, this work initially discussed the toxicological response of Cd stress to O. oratoria from the metabolic level and provided new insights into the mechanism.

Cadmium promotes glycolysis upregulation and glutamine dependency in human neuronal cells

Cadmium is a widespread pollutant, which easily accumulates inside the human body with an estimated half-life of 25-30 years. Many data strongly suggest that it may play a role in the pathogenesis of neurodegenerative diseases. In this paper we investigated cadmium effect on human SH-SY5Y neuroblastoma cells metabolism. Results showed that, although SH-SY5Y cells already showed hyperactivated glycolysis, cadmium further increased basal glycolytic rate. Both glycolytic capacity and reserve were also increased following cadmium administration, endowing the cells with a higher compensatory glycolysis when oxidative phosphorylation was inhibited. Cadmium administration also led to an increase in glycolytic ATP production rate, paralleled by a decrease in ATP production by oxidative phosphorylation, due to an impairment of mitochondrial respiration. Moreover, following cadmium administration, mitochondria increased their dependency on glutamine, while decreasing lipids oxidation. On the whole, our data show that cadmium exacerbates the Warburg effect and promotes the use of glutamine as a substrate for lipid biosynthesis. Although increased glutamine consumption leads to an increase in glutathione level, this cannot efficiently counteract cadmium-induced oxidative stress, leading to membrane lipid peroxidation. Oxidative stress represents a serious threat for neuronal cells and our data confirm glutathione as a key defense mechanism.

The effects and mechanisms of aloe-emodin on reversing adriamycin-induced resistance of MCF-7/ADR cells

Multidrug resistance (MDR) is one of the major obstacles for clinical effective chemotherapy. In this study, the effects and possible mechanisms of aloe-emodin (AE) were investigated on reversing the adriamycin (ADR)-induced resistance of MCF-7/ADR cells. AE could significantly reverse the ADR resistance in MCF-7/ADR cells. The combination of AE (20 μM) and ADR had no effect on the P-glycoprotein (P-gp) level, but notably promoted the accumulation of ADR in drug-resistant cells. The efflux function of P-gp required ATP, but AE reduced the intracellular ATP level. AE played a reversal role might through inhibiting the efflux function of P-gp. The research result of energy metabolism pathways indicated that combination of AE and ADR could inhibit glycolysis, tricarboxylic acid (TCA) cycle, glutamine metabolism, and related amino acid synthesis pathways. Moreover, we found AE not only reversed ADR-induced resistant but also induced autophagy as a defense mechanism. In addition, the combination of AE and ADR arrested G2/M cell cycle and induced apoptosis through DNA damage, ROS generation, caspase-3 activation. Our study indicated that AE could be a potential reversal agent to resensitize ADR resistant in tumor chemotherapy and inhibiting autophagy might be an effective strategy to further enhance the reversal activity of AE.

Metabolic signatures for safety assessment of low-level cadmium exposure on human osteoblast-like cells

Cadmium has been widely detected in the environment and various foods. The association between cadmium burden and osteoporosis has been studied in cohorts. However, the effects and mechanisms of environmental cadmium exposure on bone metabolism is poorly understood. This study aims to investigate the altered metabolites in bone cells affected by low-level cadmium by metabolomics analysis. Specifically, we used the dosage of cadmium that do not decrease the cell viability (determined by MTT assay) to treat Saos-2 cells for 24 h. ICP-MS was applied to quantify the cadmium in culture medium and cell precipitate. The cellular metabolites were extracted and analyzed by liquid chromatography-mass spectrometry. The pathway analysis based on the identified differential metabolites showed that 1 μM cadmium significantly affected citric acid cycle and malate-aspartate shuttle, while 10 μM cadmium treatment affected citric acid cycle, alanine metabolism, glucose-alanine cycle, pyrimidine metabolism and glutamate metabolism. Taken together, 1 μM cadmium exposure could suppress the electrons transportation from the cytosol to mitochondrial matrix in Saos-2, and the impediment of the electron transport chain further inhibited downstream activities in citric acid cycle, which resulted in the accumulation of pyruvic acid. In addition, the suppressed pyrimidine degradation resulted in senescent nucleic acid accumulation and the decrease of mRNA transcription in Saos-2 cells. In general, our studies unveil the cadmium-induced metabolic perturbations in Saos-2 cells and demonstrate the feasibility of our established metabolomics pipeline to understand cadmium-induced effects on bone.

Hepatopancreatic metabolomics shedding light on the mechanism underlying unsynchronized growth in giant freshwater prawn, Macrobrachium rosenbergii

The giant freshwater prawn, Macrobrachium rosenbergii (M. rosenbergii) as an important freshwater aquaculture species with high commercial value, exhibited unsynchronized growth. However, the potentially metabolic mechanism remains unclear. In this study, we used liquid chromatography tandem mass spectrometry (LC-MS/MS) to investigate the hepatopancreatic metabolic profiles of twenty giant freshwater prawns between the fast-growing group and slow-growing group. In the metabolomics assay, we isolated 8,293 peaks in positive and negative iron mode. Subsequently, 44 significantly differential metabolites were identified. Functional pathway analysis revealed that these metabolites were significantly enriched in three key metabolic pathways. Further integrated analysis indicated that glycerophospholipid metabolism and aminoacyl-tRNA biosynthesis have significant impact on growth performance in M.rosenbergii. Our findings presented here demonstrated the critical metabolites and metabolic pathways involved in growth performance, moreover provided strong evidence for elucidating the potentially metabolic mechanism of the unsynchronized growth in M. rosenbergii.

Lactobacillus plantarum Y44 alleviates oxidative stress by regulating gut microbiota and colonic barrier function in Balb/C mice with subcutaneous d-galactose injection

Probiotics have been proved to ameliorate the symptoms of the host induced by oxidative stress. In this study, the protective effects of Lactobacillus plantarum Y44 on Balb/C mice injured by d-galactose (d-gal)-injection were examined. Six weeks of continuous subcutaneous d-gal injection caused liver and colon injury of the Balb/C mice. L. plantarum Y44 administration significantly reversed the injury by modulating hepatic protein expressions related to the Nrf-2/Keap-1 pathway, and enhancing expressions of colonic tight junction proteins. L. plantarum Y44 administration restored the d-gal injection-induced gut microbiota imbalance by manipulating the ratio of Firmicutes/Bacteroidetes (F/B) and Proteobacteria relative abundance at the phylum level, and manipulating relative abundances of Lactobacillaceae, Muribaculaceae, Ruminococcaceae, Desulfovibrionaceae, and Prevotellaceae at the family level. Moreover, the d-gal injection-induced glycerophospholipid metabolism disorder was ameliorated, evidenced by the decline of phosphatidyl ethanolamine (PE), phosphatidylcholine (PC), phosphatidyl serine (PS), and lysophosphatidyl choline (LysoPC) levels in the serum of the mice after the L. plantarum Y44 administration. Spearman correlation analysis revealed a significant correlation between changes in gut microbiota composition, glycerophospholipid levels, and oxidative stress-related indicators. In summary, L. plantarum Y44 administration ameliorated d-gal injection-induced oxidative stress in Balb/C mice by manipulating gut microbiota and intestinal barrier function, and further influenced the glycerophospholipid metabolism and hepatic Nrf-2/Keap-1 pathway-related protein expressions.

Analysis of Cadmium, Epigallocatechin Gallate, and Vitamin C Co-exposure on PC12 Cellular Mechanisms

Exposure to cadmium (Cd) is a risk factor to health impairments, wherein its cytotoxicity is attributed to induction of oxidative stress. Usage of anti-oxidants, however, can help lessen the damaging effects of Cd. The effect of Cd interaction with low concentration of dietary anti-oxidants, L-ascorbic acid and (-)-epigallocatechin gallate (EGCG), to PC12 cellular mechanisms was examined. The expected toxicity of Cd was observed on PC12 cells but addition of L-ascorbic acid ameliorated this effect. On the other hand, addition of EGCG was able to increase the cytotoxicity of Cd and to decrease the protective effect of L-ascorbic acid against Cd. Increase in LDH activity and decrease in free sulfhydryl levels indicated cell membrane damage and oxidative stress, respectively, in Cd- and EGCG-Cd-treated cells. Downregulation of pro-apoptotic proteins (pro-caspase-9, p53, and ERK1) was observed in cells treated with Cd alone and EGCG-Cd, while upregulation of autophagy-linked proteins (p62 and pBeclin1) was found on L-ascorbic acid-Cd combination treatments. These findings indicate that Cd causes cells to undergo an autophagy-enhanced cell death; low-concentration EGCG and L-ascorbic acid promotes cell survival individually; however, interaction of EGCG with Cd showed enhancement of Cd toxicity and antagonism of L-ascorbic acid efficiency.

Emerging risk of environmental factors: insight mechanisms of Alzheimer's diseases

Neurodegenerative disorders are typically sporadic in nature in addition to usually influenced through an extensive range of environmental factors, lifestyle, and genetic elements. Latest observations have hypothesized that exposure of environmental factors may increase the prospective risk of Alzheimer's diseases (AD). However, the role of environmental factors as a possible dangerous issue has extended importance concerned in AD pathology, although actual etiology of the disorder is still not yet clear. Thus, the aim of this review is to highlight the possible correlation between environmental factors and AD, based on the present literature view. Environmental risk factors might play an important role in decelerating or accelerating AD progression. Among well-known environmental risk factors, prolonged exposure to several heavy metals, for example, aluminum, arsenic, cadmium, lead, and mercury; particulate air, and some pesticides as well as metal-containing nanoparticles have been participated to cause AD. These heavy metals have the capacity to enhance amyloid β (Aβ) peptide along with tau phosphorylation, initiating amyloid/senile plaques, as well as neurofibrillary tangle formation; therefore, neuronal cell death has been observed. Furthermore, particulate air, pesticides, and heavy metal exposure have been recommended to lead AD susceptibility and phenotypic diversity though epigenetic mechanisms. Therefore, this review deliberates recent findings detailing the mechanisms for a better understanding the relationship between AD and environmental risk factors along with their mechanisms of action on the brain functions.

Integrative serum metabolomics and network analysis on mechanisms exploration of Ling-Gui-Zhu-Gan Decoction on doxorubicin-induced heart failure mice

ETHNOPHARMACOLOGICAL RELEVANCE

Ling-Gui-Zhu-Gan Decoction (LGZGD) formula, derived from traditional Chinese medicine (TCM), has definitive clinical efficacy in the treatment of heart failure (HF) in China. However, little is known of the underlying mechanism of LGZGD.

AIM OF THE STUDY

The aim of this work was to investigate the therapeutic mechanism of LGZGD on HF treatment based on an integration of the serum metabolomics and network analysis.

MATERIALS AND METHODS

HF model mice were established by intraperitoneal injecting of doxorubicin. Body weight, echocardiography, biochemical assay and hematoxylin and eosin staining experiments were used to evaluate the efficacy of LGZGD. A metabolomics approach based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was performed to analyze the serum biomarkers from model group, control group and LGZGD-treatment group. Principle component analysis (PCA) and orthogonal projection to latent structures-discriminant analysis (OPLS-DA) were utilized to identify differences of metabolic profiles in mice among the three groups. The network of "gene-enzyme-metabolite" was built to investigate the possible mechanism of LGZGD from the systematic perspective.

RESULTS

54 metabolites, which showed a significantly restoring trend from HF to normal condition, were regarded as potential biomarkers of LGZGD treatment. The most critical pathway was glycerophospholipid metabolism and arachidonic acid metabolism. According to the results of network analysis, 8 biomarkers were regarded as hub metabolites, which meant these metabolites may have a major relationship with the LGZGD therapeutic effects for the HF. 8 enzymes and 29 genes in the network were considered as potential targets of LGZGD treatment.

CONCLUSIONS

By integrated serum metabolomic and network analysis, we found that LGZGD might retard the pathological process of HF by regulating the disturbed metabolic pathways and the relative enzymes, which may be potential mechanism for LGZGD in the treatment of HF.

Analysis of low-molecular-weight metabolites in stomach cancer cells by a simplified and inexpensive GC/MS metabolomics method

GC/MS coupled metabolomics analysis, using a simplified and much less expensive silylation process with trimethylsilyl cyanide (TMSCN), was conducted to investigate metabolic abnormalities in stomach cancer cells. Under optimized conditions for derivatization by TMSCN and methanol extraction, 228 metabolites were detected using GC/MS spectrometry analysis, and 89 metabolites were identified using standard compounds and the NIST database. Ten metabolite levels were found to be lower in stomach cancer cells relative to normal cells. Among those ten metabolites, four metabolites-ribose, proline, pyroglutamic acid, and glucose-were known to be linked to cancers. In particular, pyroglutamic acid level showed a drastic reduction of 22-fold in stomach cancer cells. Since glutamine and glutamic acid are known to undergo cyclization to pyroglutamic acid, the 22-fold reduction might be the actual reduction in the levels of glutamine and/or glutamic acid-both known to be cancer-related. Hence, the marked reduction in pyroglutamic acid level might serve as a biomarker to aid early detection of stomach cancer. Graphical abstract.

Cell metabolomics to study the cytotoxicity of carbon black nanoparticles on A549 cells using UHPLC-Q/TOF-MS and multivariate data analysis

Carbon black nanoparticles (CBNPs) are core component of fine particulate matter (PM2.5) in the atmosphere. It was reported that the particle in the atmosphere with smaller size and the larger the specific surface area are easier to reach the deep respiratory tract or even the alveoli through the respiratory barrier and cause lung injury. Therefore, it has been believed that ultrafine or nanometer particles with more toxic than those with larger particle sizes. Moreover, it was confirmed that CBNPs could induce inflammation, oxidative stress and changes in cell signaling and gene expression in mammalian cells and organs. However, the cytotoxicity mechanism of them has been uncertain so far. The aim of the present study was to explore the underlying mechanism of cytotoxicity induced by CBNPs on A549 cells. In the current research, the viabilities of A549 cells were detected by Cell Counting Kit-8 (CCK-8) assay. The further metabolomics studies were conducted to detect the cytotoxic effect of CBNPs on A549 cells with an IC50 value of 70 μg/mL for 48 h. Potential differential compounds were identified and quantified using a novel on-line acquisition method based on ultra-liquid chromatography quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF/MS). The cytotoxicity mechanism of CBNPs on A549 cells was evaluated by multivariate data analysis and statistics. As a result, a total of 32 differential compounds were identified between CBNPs exposure and control groups. In addition, pathway analysis showed the metabolic changes were involved in the tricarboxylic acid (TCA) cycle, alanine, aspartate and glutamate metabolism, histidine metabolism and so on. It is also suggested that CBNPs may induce cytotoxicity by affecting the normal process of energy metabolism and disturbing several vital signaling pathways and finally induce cell apoptosis.

Application of metabolomics to characterize environmental pollutant toxicity and disease risks

The increased incidence of non-communicable human diseases may be attributed, at least partially, to exposures to toxic chemicals such as persistent organic pollutants (POPs), air pollutants and heavy metals. Given the high mortality and morbidity of pollutant exposure associated diseases, a better understanding of the related mechanisms of toxicity and impacts on the endogenous host metabolism are needed. The metabolome represents the collection of the intermediates and end products of cellular processes, and is the most proximal reporter of the body's response to environmental exposures and pathological processes. Metabolomics is a powerful tool for studying how organisms interact with their environment and how these interactions shape diseases related to pollutant exposure. This mini review discusses potential biological mechanisms that link pollutant exposure to metabolic disturbances and chronic human diseases, with a focus on recent studies that demonstrate the application of metabolomics as a tool to elucidate biochemical modes of actions of various environmental pollutants. In addition, classes of metabolites that have been shown to be modulated by multiple environmental pollutants will be discussed with an emphasis on their use as potential early biomarkers of disease risks. Taken together, metabolomics is a useful and versatile tool for characterizing the disease risks and mechanisms associated with various environmental pollutants.

Baicalin ameliorates chronic mild stress-induced depression-like behaviors in mice and attenuates inflammatory cytokines and oxidative stress

The natural flavonoid glycoside baicalin (BA) produces a variety of pharmaceutical effects, particularly for psychiatric/neurological disorders. This study evaluated the behavioral and neuroprotective effects of BA in mice subjected to chronic unpredictable mild stress, a model of depression. BA (25 and 50 mg/kg) significantly increased sucrose consumption and reduced immobility times in the tail suspension and forced swim tests, demonstrating that BA alleviated depression-like behaviors. Moreover, BA reduced the levels of inflammatory cytokines, such as interleukin 1β, interleukin 6, and tumor necrosis factor α, in serum and in the hippocampus. BA also abrogated increases in NMDAR/NR2B and Ca²⁺/calmodulin-dependent protein kinase II, and the decrease in phosphorylated ERK and reactive oxygen species production in mice subjected to chronic unpredictable mild stress. These findings suggested that the antidepressive effects of BA are due to the regulation of an NMDAR/NR2B-ERK1/2-related pathway and inhibition of inflammatory cytokines and oxidative stress. Thus, BA represents a potential candidate drug for patients suffering from depression.

Immunosuppression, oxidative stress, and glycometabolism disorder caused by cadmium in common carp (Cyprinus carpio L.): Application of transcriptome analysis in risk assessment of environmental contaminant cadmium

Cadmium (Cd), a hazardous environmental contaminant with irreversible toxicity to fish, has been detected in aquatic environment of many countries. The common carp is one of the most widely distributed fish in the world, so we used common carp to assess environmental contaminant risk. In present study, we investigated effects of Cd on immune function, oxidative defense, and glycometabolism in the spleens of common carp by transcriptome analysis. Obtained 3794 differentially expressed genes (including 1848 up-regulated and 1946 down-regulated genes) were enriched using databases of Kyoto Encyclopedia of Genes and Genomes, and Gene Ontology in David bioinformatics software (version 6.8). The pathways and gene functions of immune, oxidative defense, and glycometabolism were obtained and identified. Some relative genes were validated using qRT-PCR and gene expression of IL-1β, INF-γ, IL-6, Cxcl18b, HO-1a, CAT, GPx1, GCK, and FBA decreased; and gene expression of B4GALT1, GPAT3, and CYP26B1 increased. Our results indicated that Cd exposure led to immunosuppression, oxidative stress, and glycometabolism disorder in the common carp spleens. The present study gives a novel insight and method on environmental risk assessment.

Analysis of glycerophospholipid metabolism after exposure to PCB153 in PC12 cells through targeted lipidomics by UHPLC-MS/MS

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that have neurotoxicity, reproductive toxicity, hepatotoxicity and immunotoxicity in both animals and humans. Few studies have focused on the changes to endogenous glycerophospholipid metabolism caused by PCB153. To evaluate the relationships between exposure to PCB153 and specific endogenous glycerophospholipid metabolism, an ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was implemented in this study. Twenty-two endogenous glycerophospholipids in PC12 cells were analyzed after exposure to PCB153 at dosages of 0.05 μg mL^-1, 0.5 μg mL^-1 or 20 μg mL^-1 for 120 h. PC(14:0/14:0), PE(16:0/18:1), PE(16:0/18:2), PS(18:0/18:1) and PI(16:0/18:1) were identified as potential biomarkers under the rules of t-test (P) value < 0.05 and variable importance at projection (VIP) value > 1. It was also found that the alterations at 0.05 μg mL^-1 and 20 μg mL^-1 PCB153 were similar at 120 h, while 0.5 μg mL^-1 PCB153 presented an opposite trend. Additionally, significant upregulation of PC, PE and PS with the same fatty acid chains of 18:0/18:2 was found after exposure to 0.05 μg mL^-1 and 20 μg mL^-1 PCB153 at 120 h. This study revealed that PCB153 exposure modulated 22 endogenous glycerophospholipids in PC12 cells and provided the basis for the further study of PCB153 on the effects of glycerophospholipids on PC12 cells.

EDTA Chelation Therapy for the Treatment of Neurotoxicity

Neurotoxicity can be caused by numerous direct agents, of which toxic metals, organophosphorus pesticides, air pollution, radiation and electromagnetic fields, neurotoxins, chemotherapeutic and anesthetic drugs, and pathogens are the most important. Other indirect causes of neurotoxicity are cytokine and/or reactive oxygen species production and adoptive immunotherapy. The development of neurodegenerative diseases has been associated with neurotoxicity. Which arms are useful to prevent or eliminate neurotoxicity? The chelating agent calcium disodium ethylenediaminetetraacetic acid (EDTA)-previously used to treat cardiovascular diseases-is known to be useful for the treatment of neurodegenerative diseases. This review describes how EDTA functions as a therapeutic agent for these diseases. Some case studies are reported to confirm our findings.

Reversal of multidrug resistance in breast cancer cells by a combination of ursolic acid with doxorubicin

Multidrug resistance (MDR) has seriously affected or hindered the effect of chemotherapy. Ursolic acid (UA) as a natural compound exhibits a number of potential biological effects including antitumor. Searching for the reversal agents from the natural products has been an effective strategy recently applied in overcoming the MDR. So in this study, the reversal effect of UA on the MDR and involved mechanisms were investigated via a multidrug-resistant MCF-7/ADR cells model and ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analytical methods. The synergistic effects were yielded by the combination of UA and Dox based on the investigation of the intracellular accumulation, the P-glycoprotein (P-gp) mediated transport, the energy metabolism including glycolysis, tricarboxylic acid (TCA) cycle, and glutamine metabolism as well as related amino acid metabolism. Obtained results showed that the UA could increase amount of doxorubicin (Dox) entering the cell to accumulate in nuclei, decrease the efflux ratio of digoxin comparable to the effects of the known inhibitor verapamil by acting as a P-gp substrate, decrease the content of intracellular alanine, lactate, pyruvate, glucose, α-ketoglutarate, glutamate, glutamine, aspartate, serine, and glycine. Taken together, inhibition of P-gp function and disruption of the metabolism of energy and related amino acids could be the key mechanisms by which UA could reverse the MDR. The findings also indicated that UA could be a potential alternative adjuvant antitumour herbal medicine to resensitize cells with MDR to chemotherapeutic agents.

Metabolomic study of natrin-induced apoptosis in SMMC-7721 hepatocellular carcinoma cells by ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry

Natrin, a new member of the cysteine-rich secretory protein (CRISP) family purified from the snake venom of Naja naja atra, has been demonstrated to have anticancer activity. However, the underlying molecular mechanisms need further elucidation. In this study, MTT was used to evaluate cell viability. Apoptotic cells were analyzed by employing a transmission electron microscope (TEM). Metabolomic study of the metabolic perturbations caused by natrin-induced apoptosis in differentiated SMMC-7721 cells was performed for the first time by using integrative ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF MS). To investigate the possible mechanism in the mitochondrial pathway of natrin-induced apoptosis, we measured apoptosis-related mRNA changes using real-time fluorescent quantitative PCR (FQ-PCR). Cell proliferation was significantly inhibited after treatment with natrin in a dose-dependent manner. Principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA) clearly demonstrated that metabolic profiles were affected by natrin. The results of multivariate statistical analysis showed that a total of 13 metabolites were characterized as potential biomarkers highly implicated in natrin-induced apoptosis, which corresponded to fluctuations of five pathways, including sphingolipid metabolism, fatty acid biosynthesis, fatty acid metabolism, glycerophospholipid metabolism and glycosphingolipid biosynthesis. Furthermore, natrin-induced apoptosis showed an increase in the Bax/Bcl-2 ratio in the mitochondrial pathway compared with controls. This study illustrated that rapid and holistic cell metabolomics combining molecular biological approaches might be a powerful tool for evaluating the underlying mechanisms of natrin-induced apoptosis, which would help to deepen specific insights into the anti-hepatoma mechanisms of natrin and facilitate the clinical application of natrin in the future.