The critical role of phosphatidylcholine and phosphatidylethanolamine metabolism in health and disease

Untargeted Metabolomic Analysis of the Effects and Mechanism of Nuciferine Treatment on Rats With Nonalcoholic Fatty Liver Disease

Metabolomic analysis has been used to characterize the effects and mechanisms of drugs for nonalcoholic fatty liver disease (NAFLD) at the metabolic level. Nuciferine is an active component derived from folium nelumbinis and has been demonstrated to have beneficial effects on a high-fat diet (HFD) induced hepatic steatosis model. However, the effect of the altered metabolites of nuciferine on NAFLD has not yet been elucidated. In this study, we established a NAFLD rat model using HFD and treated with nuciferine. The lipid content levels, pro-inflammatory cytokines, and oxidative stress were investigated to access the therapeutic effects of nuciferine. Additionally, the metabolic regulatory mechanisms of nuciferine on NAFLD were analyzed using untargeted metabolomics. Gene expression of the key enzymes related to the changed metabolic pathways following nuciferine intervention was also investigated. The results showed that nuciferine treatment significantly reduced the body weight, levels of lipids, and liver enzymes in the blood and improved the hepatic steatosis in the NAFLD rat model. Nuciferine treatment also increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreased the levels of methane dicarboxylic aldehyde (MDA) in the liver. Nuciferine treatment decreased the serum levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor-alpha (TNF-α) and upregulated the gene expression of IL-6, IL-1β, and TNF-α in the liver. Metabolomic analysis indicated a metabolism disorder in the NAFLD rat model reflected in a dysfunction of the glycerophospholipid, linoleic acid, alpha-linolenic acid, arginine and proline metabolism. Conversely, treatment with nuciferine improved the metabolic disorder in the NAFLD rat model. Nuciferine treatment also regulated the gene expression of key enzymes related to the glycerophospholipid, linoleic acid, and alpha-linolenic acid metabolism pathways in the liver. In conclusion, our study demonstrated an amelioration of the metabolic disorders following nuciferine treatment in NAFLD rat model. Our study contributes to the understanding of the effects and mechanisms of drugs for complex diseases using metabolomic analysis and experimental approaches.

Hepatic Choline Transport Is Inhibited During Fatty Acid-Induced Lipotoxicity and Obesity

Choline is an essential nutrient and a critical component of the membrane phospholipid phosphatidylcholine (PC), the neurotransmitter acetylcholine, while also contributing to the methylation pathway. In the liver specifically, PC is the major membrane constituent and can be synthesized by the cytidine diphosphate-choline or the phosphatidylethanolamine N-methyltransferase pathway. With the continuing global rise in the rates of obesity and nonalcoholic fatty liver disease, we sought to explore how excess fatty acids on primary hepatocytes and diet-induced obesity affect choline uptake and metabolism. Our results demonstrate that hepatocytes chronically treated with palmitate, but not oleate or a mixture, had decreased choline uptake, which was associated with lower choline incorporation into PC and lower expression of choline transport proteins. Interestingly, a reduction in the rate of degradation spared PC levels in response to palmitate when compared with control. The effects of palmitate treatment were independent of endoplasmic reticulum stress, which counterintuitively augmented choline transport and transporter expression. In a model of obesity-induced hepatic steatosis, male mice fed a 60% high-fat diet for 10 weeks had significantly diminished hepatic choline uptake compared with lean mice fed a control diet. Although the transcript and protein expression of various choline metabolic enzymes fluctuated slightly, we observed reduced protein expression of choline transporter-like 1 (CTL1) in the liver of mice fed a high-fat diet. Polysome profile analyses revealed that in livers of obese mice, the CTL1 transcript, despite being more abundant, was translated to a lesser extent compared with lean controls. Finally, human liver cells demonstrated a similar response to palmitate treatment. Conclusion: Our results suggest that the altered fatty acid milieu seen in obesity-induced fatty liver disease progression may adversely affect choline metabolism, potentially through CTL1, but that compensatory mechanisms work to maintain phospholipid homeostasis.

Associations between Circulating Lipids and Fat-Soluble Vitamins and Carotenoids in Healthy Overweight and Obese Men

Inconsistent associations between lipids and circulating markers of fat-soluble vitamin and carotenoid status have been reported. The aim of this hypothesis-generating study was to examine the contribution of the LC-MS-based lipidome, characterized by lipid class, carbon count, and the number of unsaturated bonds, to the interindividual variability in circulating concentrations of retinol, carotenoids, 25-hydroxyvitamin D3, α-tocopherol, γ-tocopherol, and phylloquinone in 35 overweight and obese, but healthy men. A sparse partial least-squares method was used to accomplish this aim. Highly abundant phospholipids and triglycerides (TGs) contributed to the interindividual variability in phylloquinone, α-tocopherol, and γ-tocopherol. Interindividual variability in lycopene concentrations was driven by concentrations of low-abundant TG. 25-Hydroxyvitamin D3, retinol, and the other carotenoids were not influenced by lipids. Except for lycopene, evaluation of lipids beyond class does not appear to further explain the interindividual variability in circulating concentrations of fat-soluble vitamins and carotenoids.

Enhanced Resorption of Liposomal Packed Vitamin C Monitored by Ultrasound

Vitamin C is an essential nutrient for humans and is involved in a plethora of health-related functions. Several studies have shown a connection between vitamin C intake and an improved resistance to infections that involves the immune system. However, the body cannot store vitamin C and both the elevated oral intake, and the intravenous application have certain disadvantages. In this study, we wanted to show a new formulation for the liposomal packaging of vitamin C. Using freeze etching electron microscopy, we show the formed liposomes. With a novel approach of post-processing procedures of real-time sonography that combines enhancement effects by contrast-like ultrasound with a transducer, we wanted to demonstrate the elevated intestinal vitamin C resorption on four participants. With the method presented in this study, it is possible to make use of the liposomal packaging of vitamin C with simple household materials and equipment for intake elevation. For the first time, we show the enhanced resorption of ingested liposomes using microbubble enhanced ultrasound imaging.

A novel multi-marker discovery approach identifies new serum biomarkers for Parkinson's disease in older people: an EXosomes in PArkiNson Disease (EXPAND) ancillary study

Dopaminergic nigrostriatal denervation and widespread intracellular α-synuclein accumulation are neuropathologic hallmarks of Parkinson's disease (PD). A constellation of peripheral processes, including metabolic and inflammatory changes, are thought to contribute to neurodegeneration. In the present study, we sought to obtain insight into the multifaceted pathophysiology of PD through the application of a multi-marker discovery approach. Fifty older adults aged 70+, 20 with PD and 30 age-matched controls were enrolled as part of the EXosomes in PArkiNson Disease (EXPAND) study. A panel of 68 circulating mediators of inflammation, neurogenesis and neural plasticity, and amino acid metabolism was assayed. Biomarker selection was accomplished through sequential and orthogonalized covariance selection (SO-CovSel), a multi-platform regression method developed to handle highly correlated variables organized in multi-block datasets. The SO-CovSel model with the best prediction ability using the smallest number of variables was built with seven biomolecules. The model allowed correct classification of 94.2 ± 3.1% participants with PD and 100% controls. The biomarker profile of older adults with PD was defined by higher circulating levels of interleukin (IL) 8, macrophage inflammatory protein (MIP)-1β, phosphoethanolamine, and proline, and by lower concentrations of citrulline, IL9, and MIP-1α. Our innovative approach allowed identifying and evaluating the classification performance of a set of potential biomarkers for PD in older adults. Future studies are warranted to establish whether these biomolecules could serve as biomarkers for PD as well as unveil new targets for interventions.

Hepatic lipid droplet homeostasis and fatty liver disease

In cells, lipids are stored in lipid droplets, dynamic organelles that adapt their size, abundance, lipid and protein composition and organelle interactions to metabolic changes. Lipid droplet accumulation in the liver is the hallmark of non-alcoholic fatty liver disease (NAFLD). Due to the prevalence of obesity, the strongest risk factor for steatosis, NAFLD and its associated complications are currently affecting more than 1 billion people worldwide. Here, we review how triglyceride and phospholipid homeostasis are regulated in hepatocytes and how imbalances between lipid storage, degradation and lipoprotein secretion lead to NAFLD. We discuss how organelle interactions are altered in NAFLD and provide insights how NAFLD progression is associated with changes in hepatocellular signaling and organ-crosstalk. Finally, we highlight unsolved questions in hepatic LD and lipoprotein biology and give an outlook on therapeutic options counteracting hepatic lipid accumulation.

AGXT2L1 is downregulated in carcinomas of the digestive system

Alanine-glyoxylate aminotransferase 2-like 1 (AGXT2L1) is a modulator of phospholipid metabolism, and its role in tumor biology is obscure. Previously, significant downregulation of AGXT2L1 has been observed in hepatocellular carcinoma. The aim of the present study was to investigate AGXT2L1 expression and its association with the clinical characteristics of common carcinomas of the digestive system. In the present study, the expression levels of AGXT2L1 were detected by immunohistochemical staining in colorectal cancer (CRC), gastric cancer and pancreatic cancer tissues. The associations between AGXT2L1 expression and clinicopathological features were analyzed using public gene expression datasets. Small interfering RNA was transfected into SW480 and HCT116 cells to explore the role of AGXT2L1 in CRC cells. AGXT2L1 expression was significantly decreased in cancerous tissues compared with in normal tissues, and low AGXT2L1 expression was associated with an unfavorable prognosis in patients. Furthermore, it was revealed that AGXT2L1 may regulate phosphatidylinositol and phosphatidylserine metabolism in cancerous tissues, and that decreased AGXT2L1 expression could induce autophagy in CRC cells. Overall, the present study provides a basis for further understanding of the role of AGXT2L1 and its association with autophagy in cancer.

The Ability of Quercetin and Ferulic Acid to Lower Stored Fat is Dependent on the Metabolic Background of Human Adipocytes

SCOPE

Dietary flavonoids and phenolic acids can modulate lipid metabolism, but effects on mature human adipocytes are not well characterized.

MATERIALS AND METHODS

Human adipocytes are differentiated, and contain accumulated lipids, mimicking white adipocytes. They are then cultured either under conditions of actively synthesizing and accumulating additional lipids through lipogenesis ("ongoing lipogenic state") or under conditions of maintaining but not increasing stored lipids ("lipid storage state"). Total lipid, lipidomic and transcriptomics analyses are employed to assess changes after treatment with quercetin and/or ferulic acid.

RESULTS

In the "lipid storage state," a longer-term treatment (3 doses over 72 h) with low concentrations of quercetin and ferulic acid together significantly lowered stored lipid content, modified lipid composition, and modulated genes related to lipid metabolism with a strong implication of peroxisome proliferator-activated receptor (PPARα)/retinoid X receptor (RXRα) involvement. In the "ongoing lipogenic state," the effect of quercetin and ferulic acid is markedly different, with fewer changes in gene expression and lipid composition, and no detectable involvement of PPARα/RXRα, with a tenfold higher concentration required to attenuate stored lipid content.

CONCLUSIONS

Multiple low-dose treatment of quercetin and ferulic acid modulates lipid metabolism in adipocytes, but the effect is dramatically dependent on the metabolic state of the cell.

Structural Basis for Phosphatidylethanolamine Biosynthesis by Bacterial Phosphatidylserine Decarboxylase

In both prokaryotes and eukaryotes, phosphatidylethanolamine (PE), one of the most abundant membrane phospholipids, plays important roles in various membrane functions and is synthesized through the decarboxylation of phosphatidylserine (PS) by PS decarboxylases (PSDs). However, the catalysis and substrate recognition mechanisms of PSDs remain unclear. In this study, we focused on the PSD from Escherichia coli (EcPsd) and determined the crystal structures of EcPsd in the apo form and PE-bound form at resolutions of 2.6 and 3.6 Å, respectively. EcPsd forms a homodimer, and each protomer has a positively charged substrate binding pocket at the active site. Structure-based mutational analyses revealed that conserved residues in the pocket are involved in PS decarboxylation. EcPsd has an N-terminal hydrophobic helical region that is important for membrane binding, thereby achieving efficient PS recognition. These results provide a structural basis for understanding the mechanism of PE biosynthesis by PSDs.

Maternal Caffeine Intake Disrupts Eggshell Integrity and Retards Larval Development by Reducing Yolk Production in a Caenorhabditis elegans Model

During pregnancy, most women are exposed to caffeine, which is a widely consumed psychoactive substance. However, the consequences of maternal caffeine intake on the child remain largely unknown. Here, we investigated the intergenerational effects of maternal caffeine intake on offspring in a Caenorhabditis elegans model. We treated a young mother (P0) with 10 mM of caffeine equivalent to 2–5 cans of commercial energy drinks and examined its reproduction and growth rate from P0 to F2 generation. The fertility decreased and embryonic lethality increased by defective oocytes and eggshell integrity in caffeine-ingested mothers, and F1 larval development severely retarded. These results were due to decreased production of vitellogenin protein (yolk) in caffeine-ingested mothers. Furthermore, effects of RNA interference of vitellogenin (vit) genes, vit-1 to vit-6, in P0 mothers can mimic those by caffeine-ingested mothers. In addition, RNA interference (RNAi) depletion of unc-62 (human Meis homeobox), a transcriptional activator for vit genes, also showed similar effects induced by caffeine intake. Taken together, maternal caffeine intake reduced yolk production mediated by the UNC-62 transcription factor, thereby disrupting oocyte and eggshell integrity and retarding larval development. Our study suggests the clinical significance of caffeine intake for prospective mothers.

Identification of neurotoxicity markers induced by realgar exposure in the mouse cerebral cortex using lipidomics

Realgar is a traditional Chinese medicine containing arsenic and has neurotoxicity. This study used realgar exposure mice model, neurobehavioral tests, analytical chemistry, molecular biology and nontargeted lipidomics to explore the mechanism of realgar damages the nervous system. The arsenic contained in realgar passed through the BBB and accumulated in the brain. Neurons, synapses and myelin showed abnormal changes in the cerebral cortex. The number of autophagosomes were incresed as well as levels of MDA, Lp-PLA2, and cPLA2 but the CAT level was significant reduced. Finally, the cognition and memory of mice were decreased. Nontargeted lipidomics detected 34 lipid subclasses including 1603 lipid molecules. The levels of the LPC and LPE were significantly increased. Under the condition of variable importance for the projection (VIP)>1 and P < 0.05, only 28 lipid molecules satisfied the criteria. The lipid molecular markers SM (d36:2), PE (18:2/22:6) and PE (36:3) which were filtered by receiver operating characteristic (ROC) curve (AUC>0.8 or AUC<0.2) were used to identify the neurotoxicity induced by realgar. Therefore, realgar induces neurotoxicity through exacerbating oxidative damage and lipid dysfunction. Providing research basis for the clinical diagnosis and treatment of realgar-induced neurotoxicity.

One-Carbon Metabolism in Fatty Liver Disease and Fibrosis: One-Carbon to Rule Them All

Nonalcoholic fatty liver disease (NAFLD) is a term used to characterize a range of disease states that involve the accumulation of fat in the liver but are not associated with excessive alcohol consumption. NAFLD is a prevalent disease that can progress to organ damage like liver cirrhosis and hepatocellular carcinoma. Many animal models have demonstrated that one-carbon metabolism is strongly associated with NAFLD. Phosphatidylcholine is an important phospholipid that affects hepatic lipid homeostasis and de novo synthesis of this phospholipid is associated with NAFLD. However, one-carbon metabolism serves to support all cellular methylation reactions and catabolism of methionine, serine, glycine, choline, betaine, tryptophan, and histidine. Several different pathways within one-carbon metabolism that play important roles in regulating energy metabolism and immune function have received less attention in the study of fatty liver disease and fibrosis. This review examines what we have learned about hepatic lipid metabolism and liver damage from the study of one-carbon metabolism thus far and highlights unexplored opportunities for future research.

Multi-omics systems toxicology study of mouse lung assessing the effects of aerosols from two heat-not-burn tobacco products and cigarette smoke

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Multi-omics systems toxicology study, comprising five omics data modalities.

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Multi-Omics Factor Analysis and multi-modality functional network interpretation.

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Cigarettes smoke (CS) induced complex immunoregulatory interactions across molecular layers.

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Aerosols from two heat-not-burn tobacco products had less impact on lungs than CS.

Cigarette smoke (CS) causes adverse health effects and, for smoker who do not quit, modified risk tobacco products (MRTPs) can be an alternative to reduce the risk of developing smoking-related diseases. Standard toxicological endpoints can lack sensitivity, with systems toxicology approaches yielding broader insights into toxicological mechanisms. In a 6-month systems toxicology study on ApoE^−/− mice, we conducted an integrative multi-omics analysis to assess the effects of aerosols from the Carbon Heated Tobacco Product (CHTP) 1.2 and Tobacco Heating System (THS) 2.2—a potential and a candidate MRTP based on the heat-not-burn (HnB) principle—compared with CS at matched nicotine concentrations. Molecular exposure effects in the lungs were measured by mRNA/microRNA transcriptomics, proteomics, metabolomics, and lipidomics. Integrative data analysis included Multi-Omics Factor Analysis and multi-modality functional network interpretation. Across all five data modalities, CS exposure was associated with an increased inflammatory and oxidative stress response, and lipid/surfactant alterations. Upon HnB aerosol exposure these effects were much more limited or absent, with reversal of CS-induced effects upon cessation and switching to CHTP 1.2. Functional network analysis revealed CS-induced complex immunoregulatory interactions across the investigated molecular layers (e.g., itaconate, quinolinate, and miR-146) and highlighted the engagement of the heme–Hmox–bilirubin oxidative stress axis by CS. This work exemplifies how multi-omics approaches can be leveraged within systems toxicology studies and the generated multi-omics data set can facilitate the development of analysis methods and can yield further insights into the effects of toxicological exposures on the lung of mice.

Milk Metabotyping Identifies Metabolite Alterations in the Whole Raw Milk of Dairy Cows with Lameness

The objective of this study was to evaluate whether whole raw milk originating from Holstein dairy cows affected by lameness alters its composition. A total of 20 healthy control cows and 6 cows diagnosed with lameness were selected out of 100 sampled cows in a nested case control study at 2 weeks postpartum, and whole raw milk samples were collected and analyzed with direct inject/liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance. In total, 168 metabolites were identified and quantified using an in-house mass spectrometry library. A total of 35 of the identified metabolites decreased versus control cows. Only two metabolites (i.e., sn-glycero-3-phosphocholine and phosphatidylethanolamine ae C42:1) were increased in the milk of lame cows. In conclusion, milk metabotyping of lame cows revealed significant changes in multiple milk components, including amino acids, lipids, and biogenic amines. Most of the milk compounds identified as altered were lowered, suggesting deflection of nutrients from the mammary gland to the host needs for healing lameness-associated pathological processes.

Common disbalance in the brain parenchyma of dementias: Phospholipid profile analysis between CADASIL and sporadic Alzheimer's disease

Sporadic Alzheimer's disease (SAD) is the most common form of dementia, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most frequent hereditary ischemic small vessel disease of the brain. Relevant biomarkers or specific metabolic signatures could provide powerful tools to manage these diseases. Therefore, the main goal of this study was to compare the postmortem frontal cortex gray matter, white matter and cerebrospinal fluid (CSF) between a cognitively healthy group and CADASIL and SAD groups. We evaluated 352 individual lipids, belonging to 13 lipid classes/subclasses, using mass spectrometry, and the lipid profiles were subjected to multivariate analysis to discriminate between the dementia groups (CADASIL and SAD) and healthy controls. The main lipid molecular species showing greater discrimination by partial least squares-discriminant analysis (PLS-DA) and a higher significance multivariate correlation (sMC) index were as follows: phosphatidylserine (PS) PS(44:7) and lysophosphatidylethanolamine (LPE) LPE(18:2) in gray matter (GM); phosphatidylethanolamine (PE) PE(32:2) and phosphatidylcholine PC PC(44:6) in white matter (WM), and ether PE (ePE) ePE(38:2) and ether PC (ePC) ePC(34:3) in CSF. Common phospholipid molecular species were obtained in both dementias, such as PS(44:7) and lyso PC (LPC) LPC(22:5) in GM, PE(32:2) in WM and phosphatidic acid (PA) PA(38:5) and PC(42:7) in CFS. Our exploratory study suggests that phospholipids (PLs) involved in neurotransmission alteration, connectivity impairment and inflammation response in GM, WM and CSF are a transversal phenomenon affecting dementias such as CADASIL and SAD independent of the etiopathogenesis, thus providing a possible common prodromal phospholipidic biomarker of dementia.

The Disruption of Liver Metabolic Circadian Rhythms by a Cafeteria Diet Is Sex-Dependent in Fischer 344 Rats

Circadian rhythms are ~24 h fluctuations of different biological processes that are regulated by the circadian clock system. They exert a major influence on most of the metabolism, such as the hepatic metabolism. This rhythmicity can be disrupted by obesogenic diets, fact that is considered to be a risk factor for the development of metabolic diseases. Nevertheless, obesogenic diets do not affect both genders in the same manner. We hypothesized that the circadian rhythms disruption of the hepatic metabolism, caused by obesogenic diets, is gender-dependent. Male and female Fischer 344 rats were fed either a standard diet or a cafeteria diet and sacrificed at two different moments, at zeitgeber 3 and 15. Only female rats maintained the circadian variations of the hepatic metabolism under a cafeteria diet. Most of those metabolites were related with the very low density lipoprotein (VLDL) synthesis, such as choline, betaine or phosphatidylcholine. Most of these metabolites were found to be increased at the beginning of the dark period. On the other hand, male animals did not show these time differences. These findings suggest that females might be more protected against the circadian disruption of the hepatic metabolism caused by a cafeteria diet through the increase of the VLDL synthesis at the beginning of the feeding time.

Mixture toxicity of chlorpyrifos-methyl, pirimiphos-methyl, and nonylphenol in Atlantic salmon (Salmo salar) hepatocytes

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Shotgun lipidomics points to combined effects on 18:0 and 18:1 lipid species.

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Combined effects seen on membrane phospholipids and TAG in salmon hepatocytes.

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Inhibited stearoyl CoA desaturase (SCD) and increased Δ6 desaturase (D6D) activity.

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Adjuvants may amend toxicity of active ingredient in pesticide formulations.

Pesticide formulations typically contain adjuvants added to enhance the performance of the active ingredient. Adjuvants may modify the bioavailability and toxicity of pesticides. In this study, the aim was to examine to which degree nonylphenol (NP) may interfere with the toxicity of two organophosphorus pesticides found in aquafeeds, chlorpyrifos-methyl (CPM) and pirimiphos-methyl (PPM). Atlantic salmon liver cells were exposed to these compounds singly or in combinations for 48 h using 3D cell cultures. Cytotoxicity, gene expression (RT-qPCR), and lipidomics endpoints were used to assess toxicity. The dose-response assessment showed that NP was the most toxic compound at equimolar concentrations (100 μM). Shotgun lipidomics pointed to a general pattern of elevated levels of saturated 18:0 fatty acids and declined levels of 18:1 monounsaturated fatty acids by the combined treatment. All three compounds had a distinct effect on membrane phospholipids, in particular on phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Lipid species patterns predicted inhibited stearoyl CoA desaturase (SCD) activity and increased Δ6 desaturase (D6D) activity in co-treated cells. While all three compounds alone mitigated increased triacylglycerol (TAG) accumulation, combined treatment resulted in lower total TAG in the cells. Multivariate analysis with PLS regression showed significant combined effects for nine genes (d5d, d6d, scd, srebf2, vtg, esr1, cyp1, ugt1a, and cat) and four lipid species (FFA 22:5, LPC 18:0, TAG52:1-FA16:0, and TAG52:1-FA18:0). In summary, this study demonstrates that the adjuvant can be the main contributor to the toxicity of a mixture of two organophosphorus pesticides with relatively low toxicity in fish cells.

Targeted metabolomics reveals that 2,3,7,8-tetrachlorodibenzofuran exposure induces hepatic steatosis in male mice

Environmental exposure to 2,3,7,8-tetrachlorodibenzofuran (TCDF), one of typical persistent organic pollutants (POPs) produced from municipal waste combustion, exerts toxic effects on human healthy. In the current study, we mainly used targeted metabolomics combined with untargeted ¹H NMR-based metabolomics to investigate the effects of TCDF exposure on lipid homeostasis in mice. We found that TCDF exposure induced hepatic lipogenesis, the early-stage of non-alcoholic fatty liver disease, manifested by excessive lipids including triglycerides, fatty acids and lipotoxic ceramides accumulated in the liver together with elevated serum very low-density lipoprotein by activating the aryl hydrocarbon receptor (AHR) and its target genes such as Cyp1a1 and Cd36. We also found that TCDF exposure induced alteration of phospholipids and choline metabolites and endoplasmic reticulum (ER) markers in the liver of mice, indicating that disruption of host cell membrane structural integrity and ER stress leading to hepatic steatosis. In addition, complementary information was also obtained from histopathologic assessments and biological assays, strongly supporting toxic effects of TCDF. These results provide new evidence of TCDF toxicity associated with fatty liver disease and further our understanding of health effects of environmental pollutants exposure.

Lipidomic analysis of human primary hepatocytes following LXR activation with GW3965 identifies AGXT2L1 as a main target associated to changes in phosphatidylethanolamine

Liver X receptor (LXR) agonists have the potential to alleviate obesity related diseases, particularly atherosclerosis. However, LXRs are transcriptional regulators that induce de novo lipogenesis and lipid accumulation in hepatocytes which represents a serious adverse effect. In this work, we sought to characterize the LXR agonist GW3965 effects on fatty acid (FA) and phospholipid (PL) remodelling and the correlation with gene expression in order to better understand the underlying effects leading to hepatic pathology upon LXR activation. Human primary hepatocytes treated for 48 h with GW3965 were analysed for changes in lipid metabolism gene expression by qPCR, variations in the FA profile was evaluated by GC-FID and in PL profiles using thin layer chromatography, ESI-MS and MS/MS analysis. Changes in cell membrane biochemical properties were studied using bilayer models generated with CHARMM-GUI. ELOLV6 and SCD1 mRNA increase was consistent with higher C16:1 and C18:1n9 at the expense of C16:0 and C18:0. The reduction of C18:2n6 and increase in C20:2n6 was in agreement with ELOVL5 upregulation. Phosphatydilethanolamine (PE) levels tended to decrease and phosphatidylinositol to increase; although differences did not reach significance, they correlated with changes in AGXT2L1, CDS1 and LPIN1 mRNA levels that were increased. The overall effect of GW3965 on PEs molecular profiles was an increase of long-chain polyunsaturated FA chains and a decrease of C16/C18 saturated and monounsaturated FAs chains. Additionally, PC (32:1) and PC (34:2) were decreased, and PC (36:1) and PC (34:1) were increased. AGXT2L1 is an enzyme with strict substrate specificity for phosphoethanolamine, which is converted into ammonia in GW3965-treated hepatocytes and could explain the PE reduction. In summary, LXR activation by GW3965 targets PE biosynthesis and FA elongation/desaturation, which tends to decrease PE in relation to total PL levels, and remodelling of PC and PE molecular species. We identified the human AGXT2L1 gene as induced by LXR activation by both synthetic and endogenous agonist treatment. The increase in acetaldehyde-induced oxidative stress, and in the lipid species identified have the potential to enhance the inflammatory process and impair membrane function. Future studies should focus on inhibition of AGXT2L1 activity with the aim of reverting the steatosis induced by LXR activation.

The Vitamin D Receptor Regulates Glycerolipid and Phospholipid Metabolism in Human Hepatocytes

The vitamin D receptor (VDR) must be relevant to liver lipid metabolism because VDR deficient mice are protected from hepatosteatosis. Therefore, our objective was to define the role of VDR on the overall lipid metabolism in human hepatocytes. We developed an adenoviral vector for human VDR and performed transcriptomic and metabolomic analyses of cultured human hepatocytes upon VDR activation by vitamin D (VitD). Twenty percent of the VDR responsive genes were related to lipid metabolism, including MOGAT1, LPGAT1, AGPAT2, and DGAT1 (glycerolipid metabolism); CDS1, PCTP, and MAT1A (phospholipid metabolism); and FATP2, SLC6A12, and AQP3 (uptake of fatty acids, betaine, and glycerol, respectively). They were rapidly induced (4–6 h) upon VDR activation by 10 nM VitD or 100 µM lithocholic acid (LCA). Most of these genes were also upregulated by VDR/VitD in mouse livers in vivo. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) metabolomics demonstrated intracellular accumulation of triglycerides, with concomitant decreases in diglycerides and phosphatidates, at 8 and 24 h upon VDR activation. Significant alterations in phosphatidylcholines, increases in lyso-phosphatidylcholines and decreases in phosphatidylethanolamines and phosphatidylethanolamine plasmalogens were also observed. In conclusion, active VitD/VDR signaling in hepatocytes triggers an unanticipated coordinated gene response leading to triglyceride synthesis and to important perturbations in glycerolipids and phospholipids.

Oxidative stress contributes to cerebral metabolomic profile changes in animal model of blast-induced traumatic brain injury

INTRODUCTION

Blast-induced neurotrauma (BINT) has been recognized as the common mode of traumatic brain injury amongst military and civilian personnel due to an increased insurgent activity domestically and abroad. Previous studies from this laboratory have identified three major pathological events following BINT which include blood brain barrier disruption the earliest event, followed by oxidative stress and neuroinflammation as secondary events occurring a few hours following blast.

OBJECTIVES

Our recent studies have also identified an increase in oxidative stress mediated by the activation of superoxide producing enzyme NADPH oxidase (NOX) in different brain regions at varying levels with neurons displaying higher oxidative stress (NOX activation) compared to any other neural cell. Since neurons have higher energy demands in brain and are more prone to oxidative damage, this study evaluated the effect of oxidative stress on blast-blast induced changes in metabolomics profiles in different brain regions.

METHODS

Animals were exposed to mild/moderate blast injury (180 kPa) and examined the metabolites of energy metabolism, amino acid metabolism as well as the profiles of plasma membrane metabolites in different brain regions at different time points (24 h, 3 day and 7 day) after blast using ¹H NMR spectroscopy. Effect of apocynin, an inhibitor of superoxide producing enzyme NADPH oxidase on cerebral metabalomics profiles was also examined.

RESULTS

Several metabolomic profile changes were observed in frontal cortex and hippocampus with concomitant decrease in energy metabolism. In addition, glutamate/glutamine and other amino acid metabolism as well as metabolites involved in plasma membrane integrity were also altered. Hippocampus appears metabolically more vulnerable than the frontal cortex. A post-treatment of animals with apocynin, an inhibitor of NOX activation significantly prevented the changes in metabolite profiles.

CONCLUSION

Together these studies indicate that blast injury reduces both cerebral energy and neurotransmitter amino acid metabolism and that oxidative stress contributes to these processes. Thus, strategies aimed at reducing oxidative stress can have a therapeutic benefit in mitigating metabolic changes following BINT.

Comprehensive evaluation of the metabolic effects of insect meal from Tenebrio molitor L. in growing pigs by transcriptomics, metabolomics and lipidomics

Background

The hypothesis was tested that insect meal (IM) as protein source influences intermediary metabolism of growing pigs. To test this, 30 male, 5-week-old crossbred pigs were randomly assigned to 3 groups of 10 pigs each with similar body weights (BW) and fed isonitrogenous diets either without (CON) or with 5% IM (IM5) or 10% IM (IM10) from Tenebrio molitor L. for 4 weeks and key metabolic tissues (liver, muscle, plasma) were analyzed using omics-techniques.

Results

 Most performance parameters did not differ across the groups, whereas ileal digestibilities of most amino acids were 6.7 to 15.6%-units lower in IM10 than in CON (P < 0.05). Transcriptomics of liver and skeletal muscle revealed a total of 166 and 198, respectively, transcripts differentially expressed between IM10 and CON (P < 0.05). Plasma metabolomics revealed higher concentrations of alanine, citrulline, glutamate, proline, serine, tyrosine and valine and a lower concentration of asparagine in IM10 than in CON (P < 0.05). Only one out of fourteen quantifiable amino acid metabolites, namely methionine sulfoxide (MetS), in plasma was elevated by 45% and 71% in IM5 and IM10, respectively, compared to CON (P < 0.05). Plasma concentrations of both, major carnitine/acylcarnitine species and bile acids were not different across groups. Lipidomics of liver and plasma demonstrated no differences in the concentrations of triacylglycerols, cholesterol and the main phospholipids, lysophospholipids and sphingolipids between groups. The percentages of all individual phosphatidylcholine (PC) and phosphatidylethanolamine (PE) species in the liver showed no differences between groups, except those with 6 double bonds (PC 38:6, PC 40:6, PE 38:6, PE 40:6), which were markedly lower in IM10 than in CON (P < 0.05). In line with this, the percentage of C22:6n-3 in hepatic total lipids was lower in IM10 than in the other groups (P < 0.05).

Conclusions

Comprehensive analyzes of the transcriptome, lipidome and metabolome of key metabolic tissues indicate that partial or complete replacement of a conventional protein source by IM in the diet has only a weak impact on the intermediary metabolism of growing pigs. Thus, it is concluded that IM from Tenebrio molitor L. can be used as a dietary source of protein in pigs without causing adverse effects on metabolism.

Lipid and energy metabolism in Wilson disease

Copper accumulation and deficiency are reciprocally connected to lipid metabolism. In Wilson disease (WD), which is caused by a genetic loss of function of the copper-transporting P-type ATPase beta, copper accumulates mainly in the liver and lipid metabolism is dysregulated. The underlying mechanisms linking copper and lipid metabolism in WD are not clear. Copper may impair metabolic machinery by direct binding to protein and lipid structures or by generating reactive oxygen species with consequent damage to cellular organelles vital to energy metabolism. In the liver, copper overload results in mitochondrial impairment, down-regulation of lipid metabolism, and the development of steatosis with an etiology not fully elucidated. Little is known regarding the effect of copper overload on extrahepatic energy homeostasis. This review aims to discuss alterations in hepatic energy metabolism associated with WD, highlights potential mechanisms involved in the development of hepatic and systemic dysregulation of lipid metabolism, and reviews current knowledge on the effects of copper overload on extrahepatic energy metabolism.

WZ66, a novel acetyl-CoA carboxylase inhibitor, alleviates nonalcoholic steatohepatitis (NASH) in mice

The global prevalence of nonalcoholic steatohepatitis (NASH) increases incredibly. NASH ends up to advanced liver disease, which is highly threatening to human health. Currently, treatment of NASH is very limited. Acetyl-CoA carboxylases (ACC1/ACC2) are proved as effective drug targets for NASH. We aimed to develop novel ACC inhibitors and evaluate their therapeutic value for NASH prevention. ACC inhibitors were obtained through structure-based drug design, synthesized, screened from ACC enzymatic measurement platform and elucidated in cell culture-based assays and animal models. The lipidome and microbiome analysis were integrated to assess the effects of WZ66 on lipids profiles in liver and plasma as well as gut microbiota in the intestine. WZ66 was identified as a novel ACC1/2 inhibitor. It entered systemic circulation rapidly and could accumulate in liver. WZ66 alleviated NASH-related liver features including steatosis, Kupffer cells and hepatic stellate cells activation in diet-induced obese mice. The triglycerides (TGs) and other lipids including diglycerides (DGs), phosphatidylcholine (PC) and sphingomyelin (SM) were decreased in WZ66-treated mice as evidenced by lipidome analysis in livers. The lipids profiles in plasma were also altered with WZ66 treatment. Plasma TG were moderately increased, while the activation of SREBP1c was not detected. WZ66 also downregulated the abundance of Allobaculum, Mucispirillum and Prevotella genera as well as Mucispirillum schaedleri species in gut microbiota. WZ66 is an ideal lead compound and a potential drug candidate deserving further investigation in the therapeutics of NASH.

PM2.5-induced inflammation and lipidome alteration associated with the development of atherosclerosis based on a targeted lipidomic analysis

Epidemiological studies have confirmed that PM_2.5 could contribute to the development of atherosclerosis accompanied with lipids dysregulation. However, the lipids biomarkers involved in this progress remain largely unknown. In this study, a targeted lipidomic approach was used to find out the possible lipid biomarkers involved in the development of atherosclerosis after PM_2.5 exposure or during a recovery period. Also, we assessed the pro-atherosclerosis effects of PM_2.5 and follow-up influence using pulse wave (PW) Doppler ultrasound, oil red O staining and H&E staining. The vascular stiffness was elevated after 2-month PM_2.5 exposure and might persist after 1-month recovery. While the lesions mostly concentrated in the aortic arch was significantly increased in 2-month PM_2.5 exposure group and remained an increasing trend after 1-month recovery. The expressions of pro-inflammatory cytokines detected by Mouse Inflammation Array were elevated after ApoE^-/- mice treated with PM_2.5 for 2-month and restored following 1-month recovery. Yet, IL-10 was significantly decreased during 1-month recovery. Additionally, the targeted lipidomic analysis demonstrated that cholesterol ester (CE), phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM) were significantly increased while lysophosphatidylethanolamine (LPE), lysophosphatidylcholine (LPC), diacylglycerol (DG), triacylglycerol (TG) were reduced after 2-month PM_2.5 exposure, indicating that PM_2.5 could disrupt glycerophospholipids, glycerolipids and sphingolipids metabolism. And a persistent impact of PM_2.5 on glycerophospholipids and glycerolipids metabolism was found after 1-month recovery. Our study demonstrated that PM_2.5-induced inflammation response might promote atherosclerotic lesions probably through lipid dysregulation, and the influence probably persisted after 1-month recovery.

In situ metabolite and lipid analysis of GluN2D-/- and wild-type mice after ischemic stroke using MALDI MSI

The N-methyl-D-aspartate (NMDA) receptor is a crucial mediator of pathological glutamate-driven excitotoxicity and subsequent neuronal death in acute ischemic stroke. Although the roles of the NMDAR's composite GluN2A-C subunits have been investigated in this phenomenon, the relative importance of the GluN2D subunit has yet to be evaluated. Herein, GluN2D^-/- mice were studied in a model of ischemic stroke using MALDI FT-ICR mass spectrometry imaging to investigate the role of the GluN2D subunit of the NMDA receptor in brain ischemia. GluN2D^-/- mice underwent middle cerebral artery occlusion (MCAO) and brain tissue was subsequently harvested, frozen, and cryosectioned. Tissue sections were analyzed via MALDI FT-ICR mass spectrometry imaging. MALDI analyses revealed increases in several calcium-related species, namely vitamin D metabolites, LysoPC, and several PS species, in wild-type mouse brain tissue when compared to wild type. In addition, GluN2D^-/- mice also displayed an increase in PC, as well as a decrease in DG, suggesting reduced free fatty acid release from brain ischemia. These trends indicate that GluN2D^-/- mice show enhanced rates of neurorecovery and neuroprotection from ischemic strokes compared to wild-type mice. The cause of neuroprotection may be the result of an increase in PGP in knockout mice, contributing to greater cardiolipin synthesis and decreased sensitivity to apoptotic signals. Graphical abstract.

Blood Metabolite Signatures of Metabolic Syndrome in Two Cross-Cultural Older Adult Cohorts

Metabolic syndrome (MetS) affects an increasing number of older adults worldwide. Cross-cultural comparisons can provide insight into how factors, including genetic, environmental, and lifestyle, may influence MetS prevalence. Metabolomics, which measures the biochemical products of cell processes, can be used to enhance a mechanistic understanding of how biological factors influence metabolic outcomes. In this study we examined associations between serum metabolite concentrations, representing a range of biochemical pathways and metabolic syndrome in two older adult cohorts: The Tsuruoka Metabolomics Cohort Study (TMCS) from Japan (n = 104) and the Baltimore Longitudinal Study of Aging (BLSA) from the United States (n = 146). We used logistic regression to model associations between MetS and metabolite concentrations. We found that metabolites from the phosphatidylcholines-acyl-alkyl, sphingomyelin, and hexose classes were significantly associated with MetS and risk factor outcomes in both cohorts. In BLSA, metabolites across all classes were uniquely associated with all outcomes. In TMCS, metabolites from the amino acid, biogenic amines, and free fatty acid classes were uniquely associated with MetS, and metabolites from the sphingomyelin class were uniquely associated with elevated triglycerides. The metabolites and metabolite classes we identified may be relevant for future studies exploring disease mechanisms and identifying novel precision therapy targets for individualized medicine.

Unique Distribution of Diacyl-, Alkylacyl-, and Alkenylacyl-Phosphatidylcholine Species Visualized in Pork Chop Tissues by Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging

Phosphatidylcholine (PC) is the major phospholipid in meat and influences meat qualities, such as healthiness. PC is classified into three groups based on the bond at the sn-1 position: Diacyl, alkylacyl, and alkenylacyl. To investigate their composition and distribution in pork tissues, including longissimus thoracis et lumborum (loin) spinalis muscles, intermuscular fat, and transparent tissues, we performed matrix-assisted laser desorption/ionization–mass spectrometry imaging (MALDI–MSI). Eleven diacyl-, seven alkylacyl-, and six alkenylacyl-PCs were identified using liquid chromatography (LC)-tandem MS (MS/MS) analysis. Despite many alkylacyl- and alkenylacyl-PC species sharing identical m/z values, we were able to visualize these PC species using MALDI–MSI. Diacyl- and alkylacyl- and/or alkenylacyl-PC species showed unique distribution patterns in the tissues, suggesting that their distribution patterns were dependent on their fatty acid compositions. PCs are a major dietary source of choline in meat, and the amount was significantly higher in the muscle tissues. Consumption of choline mitigates age-related memory decline and neurodegenerative diseases; therefore, the consumption of pork muscle tissues could help to mitigate these diseases. These results support the use of MALDI–MSI analysis for assessing the association between PC species and the quality parameters of meat.

Role of lipids in pathophysiology, diagnosis and therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive and widespread cancer. Patients with liver cirrhosis of different aetiologies are at a risk to develop HCC. It is important to know that in approximately 20% of cases primary liver tumors arise in a non-cirrhotic liver. Lipid metabolism is variable in patients with chronic liver diseases, and lipid metabolites involved therein do play a role in the development of HCC. Of note, lipid composition of carcinogenic tissues differs from non-affected liver tissues. High cholesterol and low ceramide levels in the tumors protect the cells from oxidative stress and apoptosis, and do also promote cell proliferation. So far, detailed characterization of the mechanisms by which lipids enable the development of HCC has received little attention. Evaluation of the complex roles of lipids in HCC is needed to better understand the pathophysiology of HCC, the later being of paramount importance for the development of urgently needed therapeutic interventions. Disturbed hepatic lipid homeostasis has systemic consequences and lipid species may emerge as promising biomarkers for early diagnosis of HCC. The challenge is to distinguish lipids specifically related to HCC from changes simply related to the underlying liver disease. This review article discusses aberrant lipid metabolism in patients with HCC.

Sex-specific perturbation of complex lipids in response to medium-chain fatty acids in very long-chain acyl-CoA dehydrogenase deficiency

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is the most common defect of long-chain fatty acid β-oxidation. The recommended treatment includes the application of medium-chain triacylglycerols (MCTs). However, long-term treatment of VLCAD^-/- mice resulted in the development of a sex-specific metabolic syndrome due to the selective activation of the ERK/mTORc1 signalling in females and ERK/peroxisome proliferator-activated receptor gamma pathway in males. In order to investigate a subsequent sex-specific effect of MCT on the lipid composition of the cellular membranes, we performed lipidomic analysis, SILAC-based quantitative proteomics and gene expression in fibroblasts from WT and VLCAD^-/- mice of both sexes. Treatment with octanoate (C8) affected the composition of complex lipids resulting in a sex-specific signature of the molecular profile. The content of ceramides and sphingomyelins in particular differed significantly under control conditions and increased markedly in cells from mutant female mice but remained unchanged in cells from mutant males. Moreover, we observed a specific upregulation of biosynthesis of plasmalogens only in male mice, whereas in females C8 led to the accumulation of higher concentration of phosphatidylcholines and lysophosphatidylcholines. Our data on membrane lipids in VLCAD after supplementation with C8 provide evidence of a sex-specific lipid perturbation. We hypothesize a likely C8-induced pro-inflammatory response contributing to the development of a severe metabolic syndrome in female VLCAD^-/- mice on long-term MCT supplementation.

Beneficial Effects of a Low-dose of Conjugated Linoleic Acid on Body Weight Gain and other Cardiometabolic Risk Factors in Cafeteria Diet-fed Rats

Conjugated linoleic acid (CLA) is a dietary supplement that has been shown to improve obesity. However, some authors have associated high doses of CLA supplementation with liver impairment and insulin resistance. The aim of this study was to assess whether the consumption of low doses of CLA maintained the beneficial effects on the main metabolic disturbances associated with metabolic syndrome (MetS) but prevented the occurrence of non-desirable outcomes associated with its consumption. Male Wistar rats, fed standard or cafeteria (CAF) diet for 12 weeks, were supplemented with three different low doses of CLA in the last three weeks. Both biochemical and H¹ NMR-based metabolomics profiles were analysed in serum and liver. The consumption of 100 mg/kg CLA, but not doses of 200 and 300 mg/kg, ameliorated the increase in body weight gain as well as the serum concentrations of glucose, insulin, cholesterol, triglyceride, diglyceride, and total phospholipid induced by a CAF diet. In turn, CLA reverted the increase in lactate, alanine, and glucose concentrations in the liver of these animals, but enhanced hepatic cholesterol accumulation without any detrimental effect on liver function. In conclusion, a low dose of CLA corrected the adverse effects associated with MetS without compromising other metabolic parameters.

Profiling of lipidomics before and after antipsychotic treatment in first-episode psychosis

Alterations in complex lipids may be involved in pathophysiology of schizophrenia spectrum disorders. Previously, we demonstrated importance of detecting lipid metabolism dysregulation by acylcarnitine (ACs) profile analysis in patients with first-episode psychosis (FEP). The aim of this study was to adopt lipidomics to identify serum glycerophospholipids (GPLs) and sphingomyelins (SMs) for describing FEP status before and after 7-month antipsychotic treatment. Using mass spectrometry and liquid chromatography technique, we profiled 105 individual lipids [14 lysophosphatidylcholines (LysoPCs), 76 phosphatidylcholines (PCs) and 15 SMs] in serum samples from 53 antipsychotic-naïve FEP patients, 44 of them were studied longitudinally and from 37 control subjects (CSs). Among the identified and quantified metabolites one LysoPC was elevated, and contrary the levels of 16 PCs as well as the level of one SM were significantly (p ≤ 0.0005) reduced in antipsychotic-naïve FEP patients compared to CSs. Comparison of serum lipids profiles of FEP patients before and after 7-month antipsychotic treatment revealed that 11 GPLs (2 LysoPCs, 9 PCs), and 2 SMs were found to be significantly changed (p ≤ 0.0005) in which GPLs were up-regulated, and SMs were down-regulated. However, no significant differences were noted when treated patient's serum lipid profiles were compared with CSs. Our findings suggest that complex lipid profile abnormalities are specifically associated with FEP and these discrepancies reflect two different disease-related pathways. Our findings provide insight into lipidomic information that may be used for monitoring FEP status and impact of the treatment in the early stage of the schizophrenia spectrum disorder.

Metabolome profiling in skeletal muscle to characterize metabolic alterations in over-conditioned cows during the periparturient period

The transition from late gestation to early lactation is associated with extensive changes in metabolic, endocrine, and immune functions in dairy cows. Skeletal muscle plays an important role in maintaining the homeorhetic adaptation to the metabolic needs of lactation. The objective of this study was to characterize the skeletal muscle metabolome in the context of the metabolic changes that occur during the transition period in dairy cows with high (HBCS) versus normal body condition (NBCS). Fifteen weeks antepartum, 38 pregnant multiparous Holstein cows were assigned to 1 of 2 groups, which were fed differently to reach the targeted BCS and back fat thickness (BFT) until dry-off at -49 d before calving (HBCS: >3.75 and >1.4 cm; NBCS: <3.5 and <1.2 cm). During the dry period and the subsequent lactation, both groups were fed identical diets. The differences in both BCS and BFT were maintained throughout the study. The metabolome was characterized in skeletal muscle samples (semitendinosus muscle) collected on d -49, 3, 21, and 84 relative to calving using a targeted metabolomics approach (AbsoluteIDQ p180 kit; Biocrates Life Sciences AG, Innsbruck, Austria), which allowed for the quantification of up to 188 metabolites from 6 different compound classes (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, sphingolipids, and hexoses). On d -49, the concentrations of citrulline and hydroxytetradecadienyl-l-carnitine in muscle were higher in HBCS cows than in NBCS cows, but those of carnosine were lower. Over-conditioning did not affect the muscle concentrations of any of the metabolites on d 3. On d 21, the concentrations of phenylethylamine and linoleylcarnitine in muscle were lower in HBCS cows than in NBCS cows, and the opposite was true for lysophosphatidylcholine acyl C20:4. On d 84, the significantly changed metabolites were mainly long-chain (>C32) acyl-alkyl phosphatidylcholine and di-acyl phosphatidylcholine, along with 3 long-chain (>C16) sphingomyelin that were all lower in HBCS cows than in NBCS cows. These data contribute to a better understanding of the metabolic adaptation in skeletal muscle of dairy cows during the transition period, although the physiological significance and underlying molecular mechanisms responsible for the regulation of citrulline, hydroxytetradecadienyl-l-carnitine, carnosine, and phenylethylamine associated with over-conditioning are still elusive and warrant further investigation. The changes observed in muscle lysophosphatidylcholine and phosphatidylcholine concentrations may point to an alteration in phosphatidylcholine metabolism, probably resulting in an increase in membrane stiffness, which may lead to abnormalities in insulin signaling in the muscle of over-conditioned cows.

Mass spectrometry based proteomics and metabolomics in personalized oncology

Precision medicine (PM) means the customization of healthcare with decisions and practices adjusted to the individual patient. It includes personalized diagnostics, patients' sub-classification, individual treatment selection and the monitoring of its effectiveness. Currently, in oncology, PM is based on the molecular and cellular features of a tumor, its microenvironment and the patient's genetics and lifestyle. Surprisingly, the available targeted therapies were found effective only in a subset of patients. An in-depth understanding of tumor biology is crucial to improve their effectiveness and develop new therapeutic targets. Completion of genetic information with proteomics and metabolomics can give broader knowledge about tumor biology which consequently provides novel biomarkers and indicates new therapeutic targets. Recently, metabolomics and proteomics have extensively been applied in the field of oncology. In the context of PM, human studies, with the use of mass spectrometry (MS) which allows the detection of thousands of molecules in a large number of samples, are the most valuable. Such studies, focused on cancer biomarkers discovery or patients' stratification, are presented in this review. Moreover, the technical aspects of MS-based clinical proteomics and metabolomics are described.

Identification of a Circulating Amino Acid Signature in Frail Older Persons with Type 2 Diabetes Mellitus: Results from the Metabofrail Study

Diabetes and frailty are highly prevalent conditions that impact the health status of older adults. Perturbations in protein/amino acid metabolism are associated with both functional impairment and type 2 diabetes mellitus (T2DM). In the present study, we compared the concentrations of a panel of circulating 37 amino acids and derivatives between frail/pre-frail older adults with T2DM and robust non-diabetic controls. Sixty-six functionally impaired older persons aged 70+ with T2DM and 30 age and sex-matched controls were included in the analysis. We applied a partial least squares-discriminant analysis (PLS-DA)-based analytical strategy to characterize the metabotype of study participants. The optimal complexity of the PLS-DA model was found to be two latent variables. The proportion of correct classification was 94.1 ± 1.9% for frail/pre-frail persons with T2DM and 100% for control participants. Functionally impaired older persons with T2DM showed higher levels of 3-methyl histidine, alanine, arginine, glutamic acid, ethanolamine sarcosine, and tryptophan. Control participants had higher levels of ornithine and taurine. These findings indicate that a specific profile of amino acids and derivatives characterizes pre-frail/frail older persons with T2DM. The dissection of these pathways may provide novel insights into the metabolic perturbations involved in the disabling cascade in older persons with T2DM.

Mass-spec-based urinary metabotyping around parturition identifies screening biomarkers for subclinical mastitis in dairy cows

The objective of this study was to determine urinary metabotypes of dairy cows prior to, during, and after diagnosis of subclinical mastitis (SCM). Twenty controls (CON) and 6 cows with SCM were included in the study. DI/LC-MS/MS was used to measure 186 metabolites in the urine at -8 and - 4 wks prepartum, disease diagnosis, and at +4 and + 8 wks postpartum. Results showed a total of 24 and 27 metabolites that differentiated SCM and CON cows at -8 and - 4 wks, respectively, with 5 top metabolites having an accuracy to predict SCM of 1.0, for both time point. Altered metabolites included several acylcarnitines (ACs), phosphatidylcholines (PCs), amino acids (AAs), and biogenic amines (BAs). During SCM diagnosis week there were a total of 22 metabolites that differentiated the SCM and CON cows including 13 ACs, 5 AAs, hexose, and phosphatidylethanolamine ae C44:3. The top 5 metabolites Symmetric dimethylarginine (SDMA), methylglutarylcarnitine, dodecanoylcarnitine, phosphatidylethanolamine ae C42:1, and phosphatidylethanolamine ae C42:0 showed an AUC of 1.0. Metabolite alterations continued at +4 and + 8 wks postpartum with 13 (9 ACs, 3 glycerophospholipids, and 1 BA) and 28 metabolites (14 ACs, 2 glycerophospholipids, hexose, 8 AAs, and 2 BAs) that differentiated the two groups, respectively. The top 5 most important metabolites, for both time points, showed AUCs of 1.0. Results of this study showed that typical urinary metabotypes preceded SCM event starting from -8 and - 4 wks prepartum. Metabotypes typical of SCM continued to be present during the week of SCM and at +4 and + 8 wks postpartum. These data show that the urine of dairy cows can be used with very high accuracy for screening dairy cows for susceptibility to SCM prior to entering into the dry off period and a potential new pen-side test can help dairy producers and veterinarians to make selective treatments.

New insights of CYP1A in endogenous metabolism: a focus on single nucleotide polymorphisms and diseases

Cytochrome P450 1A (CYP1A), one of the major CYP subfamily in humans, not only metabolizes xenobiotics including clinical drugs and pollutants in the environment, but also mediates the biotransformation of important endogenous substances. In particular, some single nucleotide polymorphisms (SNPs) for CYP1A genes may affect the metabolic ability of endogenous substances, leading to some physiological or pathological changes in humans. This review first summarizes the metabolism of endogenous substances by CYP1A, and then introduces the research progress of CYP1A SNPs, especially the research related to human diseases. Finally, the relationship between SNPs and diseases is discussed. In addition, potential animal models for CYP1A gene editing are summarized. In conclusion, CYP1A plays an important role in maintaining the health in the body.

Redox Epiphospholipidome in Programmed Cell Death Signaling: Catalytic Mechanisms and Regulation

A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane building blocks. Indeed, a number of signaling functions of (phospho)lipid molecules has been discovered. Among these signaling lipids, a particular group of oxygenated polyunsaturated fatty acids (PUFA), so called lipid mediators, has been thoroughly investigated over several decades. This group includes oxygenated octadecanoids, eicosanoids, and docosanoids and includes several hundreds of individual species. Oxygenation of PUFA can occur when they are esterified into major classes of phospholipids. Initially, these events have been associated with non-specific oxidative injury of biomembranes. An alternative concept is that these post-synthetically oxidatively modified phospholipids and their adducts with proteins are a part of a redox epiphospholipidome that represents a rich and versatile language for intra- and inter-cellular communications. The redox epiphospholipidome may include hundreds of thousands of individual molecular species acting as meaningful biological signals. This review describes the signaling role of oxygenated phospholipids in programs of regulated cell death. Although phospholipid peroxidation has been associated with almost all known cell death programs, we chose to discuss enzymatic pathways activated during apoptosis and ferroptosis and leading to peroxidation of two phospholipid classes, cardiolipins (CLs) and phosphatidylethanolamines (PEs). This is based on the available LC-MS identification and quantitative information on the respective peroxidation products of CLs and PEs. We focused on molecular mechanisms through which two proteins, a mitochondrial hemoprotein cytochrome c (cyt c), and non-heme Fe lipoxygenase (LOX), change their catalytic properties to fulfill new functions of generating oxygenated CL and PE species. Given the high selectivity and specificity of CL and PE peroxidation we argue that enzymatic reactions catalyzed by cyt c/CL complexes and 15-lipoxygenase/phosphatidylethanolamine binding protein 1 (15LOX/PEBP1) complexes dominate, at least during the initiation stage of peroxidation, in apoptosis and ferroptosis. We contrast cell-autonomous nature of CLox signaling in apoptosis correlating with its anti-inflammatory functions vs. non-cell-autonomous ferroptotic signaling facilitating pro-inflammatory (necro-inflammatory) responses. Finally, we propose that small molecule mechanism-based regulators of enzymatic phospholipid peroxidation may lead to highly specific anti-apoptotic and anti-ferroptotic therapeutic modalities.

Gut microbiota: a promising target against cardiometabolic diseases

Introduction: Cardiometabolic diseases (CMD) are a group of interrelated disorders such as metabolic syndrome, type 2 diabetes mellitus and cardiovascular diseases (CVD). As the prevalence of these diseases increases globally, efficient new strategies are necessary to target CMD and modifiable risk factors. In the past decade, evidence has accumulated regarding the influence of gut microbiota (GM) on CMD, providing new targets for therapeutic interventions.Areas covered: This narrative review discusses the pathophysiologic link between CMD, GM, and potential microbiota-based targets against atherosclerosis and modifiable risk factors for atherosclerosis. Low-grade inflammation can be induced through GM and its derived metabolites. CMD are influenced by GM and microbiota-derived metabolites such as short-chain fatty acids (SCFA), secondary bile acids, trimethylamine N-oxide (TMAO), and the composition of GM can modulate host metabolism. All of the above can lead to promising therapeutic targets.Expert opinion: Most data are derived from animal models or human association studies; therefore, more translational and interventional research in humans is necessary to validate these promising findings. Reproduced findings such as aberrant microbiota patterns or circulating biomarkers could be targeted depending on individual metabolic profiles, moving toward personalized medicine in CMD.

Metabolomic Links between Sugar-Sweetened Beverage Intake and Obesity

BACKGROUND

Sugar-sweetened beverage (SSB) consumption is highly associated with obesity, but the metabolic mechanism underlying this correlation is not understood.

OBJECTIVE

Our objective was to examine metabolomic links between SSB intake and obesity to understand metabolic mechanisms.

DESIGN

We examined the association of plasma metabolomic profiles with SSB intake and obesity risk in 781 participants, aged 45-75 y, in the Boston Puerto Rican Health Study (BPRHS) using generalized linear models, controlling for potential confounding factors. Based on identified metabolites, we conducted pathway enrichment analysis to identify potential metabolic pathways that link SSB intake and obesity risk. Variants in genes encoding enzymes known to function in identified metabolic pathways were examined for their interactions with SSB intake on obesity.

RESULTS

SSB intake was correlated with BMI (β = 0.607, P=0.045). Among 526 measured metabolites, 86 showed a significant correlation with SSB intake and 148 with BMI (P ≤ 0.05); 28 were correlated with both SSB intake and BMI (P ≤ 0.05). Pathway enrichment analysis identified the phosphatidylcholine and lysophospholipid pathways as linking SSB intake to obesity, after correction for multiple testing. Furthermore, 8 of 10 genes functioning in these two pathways showed strong interaction with SSB intake on BMI. Our results further identified participants who may exhibit an increased risk of obesity when consuming SSB.

CONCLUSIONS

We identified two key metabolic pathways that link SSB intake to obesity, revealing the potential of phosphatidylcholine and lysophospholipid to modulate how SSB intake can increase obesity risk. The interaction between genetic variants related to these pathways and SSB intake on obesity further supports the mechanism.

Overexpression of Hepatocyte Chemerin-156 Lowers Tumor Burden in a Murine Model of Diethylnitrosamine-Induced Hepatocellular Carcinoma

The tumor inhibitory potential of the highly active chemerin-156 isoform was described in orthotopic models of hepatocellular carcinoma (HCC). The majority of HCC arises in the fibrotic liver, which was not reproduced in these studies. Here, a potential therapeutic activity of chemerin-156 was evaluated in diethylnitrosamine (DEN)-induced liver cancer, which mimics fibrosis-associated HCC. Mice were infected with adeno-associated virus (AAV) six months after DEN injection to overexpress chemerin-156 in the liver, and animals injected with non-recombinant-AAV served as controls. Three months later, the animals were killed. Both groups were comparable with regard to liver steatosis and fibrosis. Of note, the number of very small tumors was reduced by chemerin-156. Anyhow, the expression of inflammatory and profibrotic genes was similar in larger tumors of control and chemerin-156-AAV-infected animals. Although genes with a role in lipid metabolism, like 3-hydroxy-3-methylglutaryl-coenzym-A--reductase, were overexpressed in tumors of animals with high chemerin-156, total hepatic cholesterol, diacylglycerol and triglyceride levels, and distribution of individual lipid species were normal. Chemerin-156-AAV-infected mice had elevated hepatic and systemic chemerin. Ex vivo activation of the chemerin receptor chemokine-like receptor 1 increased in parallel with serum chemerin, illustrating the biological activity of the recombinant protein. In the tumors, chemerin-155 was the most abundant variant. Chemerin-156 was not detected in tumors of the controls and was hardly found in chemerin-156-AAV infected animals. In conclusion, the present study showed that chemerin-156 overexpression caused a decline in the number of small lesions but did not prevent the growth of pre-existing neoplasms.

Relative Ratios Enhance the Diagnostic Power of Phospholipids in Distinguishing Benign and Cancerous Ovarian Masses

Ovarian cancer remains a highly lethal disease due to its late clinical presentation and lack of reliable early biomarkers. Protein-based diagnostic markers have presented limitations in identifying ovarian cancer. We tested the potential of phospholipids as markers of ovarian cancer by utilizing inter-related regulation of phospholipids, a unique property that allows the use of ratios between phospholipid species for quantitation. High-performance liquid chromatography mass spectrometry was used to measure phospholipid, lysophospholipid, and sphingophospholipid content in plasma from patients with benign ovarian masses, patients with ovarian cancer, and controls. We applied both absolute and relative phospholipid ratios for quantitation. Receiver operating characteristic analysis was performed to test the sensitivity and specificity. We found that utilization of ratios between phospholipid species greatly outperformed absolute quantitation in the identification of ovarian cancer. Of the phospholipids analyzed, species in phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and sphingomyelin (SM) were found to have great biomarker potential. LPC(20:4)/LPC(18:0) carried the greatest capacity to differentiate cancer from control, SM(d18:1/24:1)/SM(d18:1/22:0) to differentiate benign from cancer, and PC(18:0/20:4)/PC(18:0/18:1) to differentiate benign from control. These results demonstrate the potential of plasma phospholipids as a novel marker of ovarian cancer by utilizing the unique characteristics of phospholipids to further enhance the diagnostic power.

Oligosaccharides from Morinda officinalis Slow the Progress of Aging Mice by Regulating the Key Microbiota-Metabolite Pairs

The gut microbiota is considered an important factor in the progression of Alzheimer's disease (AD). Active research on the association between the metabolome and the gut microbiome is ongoing and can provide a large amount of beneficial information about the interactions between the microbiome and the metabolome. Previous studies have shown that the oligosaccharides from Morinda officinalis (OMO) can delay the progress of AD in model animals by regulating the diversity of the gut microbiome and metabolic components, and the correlation between the gut microbiome and metabolic components still needs to be further verified. This study applied a new two-level strategy to investigate and ensure the accuracy and consistency of the results. This strategy can be used to determine the association between the gut microbiome and serum metabolome in APP/PS1 transgenic mice and C57BL/6J male mice. The “4C0d-2 spp.-Cholesterol,” “CW040 spp.-L-valine,” “CW040 spp.-L-acetylcarnitine,” “RF39 spp.-L-valine,” “TM7-3 spp.-L-valine,” and “TM7-3 spp.-L-acetylcarnitine” associations among specific “microbiota-metabolite” pairs were further identified based on univariate and multivariate correlation analyses and functional analyses. The key relevant pairs were verified by an independent oligosaccharide intervention study, and the gut microbiome and serum metabolome of the OMO intervention group were similar to those of the normal group. The results indicate that OMO can significantly suppress Alzheimer's disease by regulating the key microbiota-metabolite pairs. Therefore, this two-level strategy is effective in identifying the principal correlations in large datasets obtained from combinations of multiomic studies and further enhancing our understanding of the correlation between the brain and gut in patients with AD.

Quantitative multi-omics analysis of the effects of mitochondrial dysfunction on lipid metabolism in Saccharomyces cerevisiae

In this study, combined genome, transcriptome, and metabolome analysis was performed for eight Saccharomyces cerevisiae mitochondrial respiration-deficient mutants. Each mutant exhibited a unique nuclear genome mutation pattern; the nuclear genome mutations, and thus potentially affected genes and metabolic pathways, showed a co-occurrence frequency of ≤ 3 among the eight mutants. For example, only a lipid metabolism-related pathway was likely to be affected by the nuclear genome mutations in one of the mutants. However, large deletions in the mitochondrial genome were the shared characteristic among the eight mutants. At the transcriptomic level, lipid metabolism was the most significantly enriched Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway for differentially expressed genes (DEGs) co-occurring in both ≥ 4 and ≥ 5 mutants. Any identified DEG enriched in lipid metabolism showed the same up-/down-regulated pattern among nearly all eight mutants. Further, 126 differentially expressed lipid species (DELS) were identified, which also showed the same up-/down-regulated pattern among nearly all investigated mutants. It was conservatively demonstrated that the similar change pattern of lipid metabolism in the entire investigated mutant population was attributed to mitochondrial dysfunction. The change spectrum of lipid species was presented, suggesting that the number and change degree of up-regulated lipid species were higher than those of down-regulated lipid species. Additionally, energy storage lipids increased in content and plasma-membrane phospholipid compositions varied in the relative proposition. The results for the genome, transcriptome, and lipidome were mutually validated, which provides quantitative data revealing the roles of mitochondria from a global cellular perspective.

The Role of Phosphatidylethanolamine Adducts in Modification of the Activity of Membrane Proteins under Oxidative Stress

Reactive oxygen species (ROS) and their derivatives, reactive aldehydes (RAs), have been implicated in the pathogenesis of many diseases, including metabolic, cardiovascular, and inflammatory disease. Understanding how RAs can modify the function of membrane proteins is critical for the design of therapeutic approaches in the above-mentioned pathologies. Over the last few decades, direct interactions of RA with proteins have been extensively studied. Yet, few studies have been performed on the modifications of membrane lipids arising from the interaction of RAs with the lipid amino group that leads to the formation of adducts. It is even less well understood how various multiple adducts affect the properties of the lipid membrane and those of embedded membrane proteins. In this short review, we discuss a crucial role of phosphatidylethanolamine (PE) and PE-derived adducts as mediators of RA effects on membrane proteins. We propose potential PE-mediated mechanisms that explain the modulation of membrane properties and the functions of membrane transporters, channels, receptors, and enzymes. We aim to highlight this new area of research and to encourage a more nuanced investigation of the complex nature of the new lipid-mediated mechanism in the modification of membrane protein function under oxidative stress.

Elevated Choline Kinase α-Mediated Choline Metabolism Supports the Prolonged Survival of TRAF3-Deficient B Lymphocytes

Specific deletion of the tumor suppressor TRAF3 from B lymphocytes in mice leads to the prolonged survival of mature B cells and expanded B cell compartments in secondary lymphoid organs. In the current study, we investigated the metabolic basis of TRAF3-mediated regulation of B cell survival by employing metabolomic, lipidomic, and transcriptomic analyses. We compared the polar metabolites, lipids, and metabolic enzymes of resting splenic B cells purified from young adult B cell-specific Traf3 ^-/- and littermate control mice. We found that multiple metabolites, lipids, and enzymes regulated by TRAF3 in B cells are clustered in the choline metabolic pathway. Using stable isotope labeling, we demonstrated that phosphocholine and phosphatidylcholine biosynthesis was markedly elevated in Traf3 ^-/- mouse B cells and decreased in TRAF3-reconstituted human multiple myeloma cells. Furthermore, pharmacological inhibition of choline kinase α, an enzyme that catalyzes phosphocholine synthesis and was strikingly increased in Traf3 ^-/- B cells, substantially reversed the survival phenotype of Traf3 ^-/- B cells both in vitro and in vivo. Taken together, our results indicate that enhanced phosphocholine and phosphatidylcholine synthesis supports the prolonged survival of Traf3 ^-/- B lymphocytes. Our findings suggest that TRAF3-regulated choline metabolism has diagnostic and therapeutic value for B cell malignancies with TRAF3 deletions or relevant mutations.

Green Tea Extract Treatment in Obese Mice with Nonalcoholic Steatohepatitis Restores the Hepatic Metabolome in Association with Limiting Endotoxemia-TLR4-NFκB-Mediated Inflammation

SCOPE

Catechin-rich green tea extract (GTE) alleviates nonalcoholic steatohepatitis (NASH) by lowering endotoxin-TLR4 (Toll-like receptor-4)-NFκB (nuclear factor kappa-B) inflammation. This study aimed to define altered MS-metabolomic responses during high-fat (HF)-induced NASH that are restored by GTE utilizing livers from an earlier study in which GTE decreased endotoxin-TLR4-NFκB liver injury.

METHODS AND RESULTS

Mice are fed a low-fat (LF) or HF diet for 12 weeks and then randomized to LF or HF diets containing 0% or 2% GTE for an additional 8 weeks. Global MS-based metabolomics and targeted metabolite profiling of catechins/catechin metabolites are evaluated. GTE in HF mice restores hepatic metabolites implicated in dyslipidemia insulin resistance, and inflammation. These include 122 metabolites: amino acids, lipids, nucleotides, vitamins, bile acids, flavonoids, xenobiotics, and carbohydrates. Hepatic amino acids, B-vitamins, and bile acids are inversely correlated with biomarkers of insulin resistance, liver injury, steatosis, and inflammation. Further, phosphatidylcholine metabolites are positively correlated with biomarkers of liver injury and NFκB inflammation. Thirteen catechin metabolites are identified in livers of GTE-treated mice, mostly as phase II conjugates of parental catechins or microbial-derived valerolactones.

CONCLUSION

The defined anti-inflammatory/metabolic interactions advance an understanding of the mechanism by which GTE catechins protect against NFκB-mediated liver injury in NASH.