Phosphatidylcholine biosynthesis and lipoprotein metabolism

A methionine-choline-deficient diet induces nonalcoholic steatohepatitis and alters the lipidome, metabolome, and gut microbiome profile in the C57BL/6J mouse

The methionine-choline-deficient (MCD) diet-induced non-alcoholic steatohepatitis (NASH) in mice is a well-established model. Our study aims to elucidate the factors influencing liver pathology in the MCD mouse model by examining physiological, biochemical, and molecular changes using histology, molecular techniques, and OMICS approaches (lipidomics, metabolomics, and metagenomics). Male C57BL/6J mice were fed a standard chow diet, a methionine-choline-sufficient (MCS) diet, or an MCD diet for 10 weeks. The MCD diet resulted in reduced body weight and fat mass, along with decreased plasma triglyceride, cholesterol, glucose, and insulin levels. However, it notably induced steatosis, inflammation, and alterations in gene expression associated with lipogenesis, inflammation, fibrosis, and the synthesis of apolipoproteins, sphingolipids, ceramides, and carboxylesterases. Lipid analysis revealed significant changes in plasma and tissues: most ceramide non-hydroxy-sphingosine lipids significantly decreased in the liver and plasma but increased in the adipose tissue of MCD diet-fed animals. Oxidized glycerophospholipids mostly increased in the liver but decreased in the adipose tissue of the MCD diet-fed group. The gut microbiome of the MCD diet-fed group showed an increase in Firmicutes and a decrease in Bacteroidetes and Actinobacteria. Metabolomic profiling demonstrated that the MCD diet significantly altered amino acid biosynthesis, metabolism, and nucleic acid metabolism pathways in plasma, liver, fecal, and cecal samples. LC-MS data indicated higher total plasma bile acid intensity and reduced fecal glycohyodeoxycholic acid intensity in the MCD diet group. This study demonstrates that although the MCD diet induces hepatic steatosis, the mechanisms underlying NASH in this model differ from those in human NASH pathology.

Serum lipidome reveals lipid metabolic dysregulation in severe fever with thrombocytopenia syndrome

BACKGROUND

Severe fever with thrombocytopenia syndrome (SFTS) is a rapidly progressing infectious disease with a high fatality rate caused by a novel bunyavirus (SFTSV). The role of lipids in viral infections is well-documented; however, the specific alterations in lipid metabolism during SFTSV infection remain elusive. This study aims to elucidate the lipid metabolic dysregulations in the early stages of SFTS patients.

METHODS

This study prospectively collected peripheral blood sera from 11 critical SFTS patients, 37 mild SFTS patients, and 23 healthy controls during the early stages of infection for lipidomics analysis. A systematic bioinformatics analysis was conducted from three aspects integrating lipid differential expressions, lipid differential correlations, and lipid-clinical indices correlations to reveal the serum lipid metabolic dysregulation in SFTSV-infected individuals.

RESULTS

Our findings reveal significant lipid metabolic dysregulation in SFTS patients. Specifically, compared to healthy controls, SFTS patients exhibited three distinct modes of lipid differential expression: increased levels of lipids including phosphatidylserine (PS), hexosylceramide (HexCer), and triglycerides (TG); decreased levels of lipids including lysophosphatidylcholine (LPC), acylcarnitine (AcCa), and cholesterol esters (ChE); and lipids showing "dual changes" including phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Finally, based on lipid metabolic pathways and literature analysis, we systematically elucidated the potential mechanisms underlying lipid metabolic dysregulation in the early stage of SFTSV infection.

CONCLUSIONS

Our study presents the first global serum lipidome profile and reveals the lipid metabolic dysregulation patterns in the early stage of SFTSV infection. These findings provide a new basis for the diagnosis, treatment, and further investigation of the disease.

Multivariable Mendelian randomization with incomplete measurements on the exposure variables in the Hispanic Community Health Study/Study of Latinos

Multivariable Mendelian randomization allows simultaneous estimation of direct causal effects of multiple exposure variables on an outcome. When the exposure variables of interest are quantitative omic features, obtaining complete data can be economically and technically challenging: the measurement cost is high, and the measurement devices may have inherent detection limits. In this paper, we propose a valid and efficient method to handle unmeasured and undetectable values of the exposure variables in a one-sample multivariable Mendelian randomization analysis with individual-level data. We estimate the direct causal effects with maximum likelihood estimation and develop an expectation-maximization algorithm to compute the estimators. We show the advantages of the proposed method through simulation studies and provide an application to the Hispanic Community Health Study/Study of Latinos, which has a large amount of unmeasured exposure data.

Biochemistry and Diseases Related to the Interconversion of Phosphatidylcholine, Phosphatidylethanolamine, and Phosphatidylserine

Phospholipids are crucial structural components of cells. Phosphatidylcholine and phosphatidylethanolamine (both synthesized via the Kennedy pathway) and phosphatidylserine undergo interconversion. The dysregulation of this process is implicated in various diseases. This paper discusses the role of enzymes involved in the interconversion of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine, specifically phosphatidylethanolamine N-methyltransferase (PEMT), phosphatidylserine synthases (PTDSS1 and PTDSS2), and phosphatidylserine decarboxylase (PISD), with a focus on their biochemical properties. Additionally, we describe the effects of the deregulation of these enzymes and their roles in both oncological and non-oncological diseases, including nonalcoholic fatty liver disease (NAFLD), Alzheimer's disease, obesity, insulin resistance, and type II diabetes. Current knowledge on inhibitors of these enzymes as potential therapeutic agents is also reviewed, although in most cases, inhibitors are yet to be developed. The final section of this article presents a bioinformatic analysis using the GEPIA portal to explore the significance of these enzymes in cancer processes.

TM6SF2 E167K variant decreases PNPLA3-mediated PUFA transfer to promote hepatic steatosis and injury in MASLD

BACKGROUNDS/AIMS

Transmembrane 6 superfamily member 2 (TM6SF2) E167K variant is closely associated with the occurrence and development of metabolic dysfunction-associated steatotic liver disease (MASLD). However, the role and mechanism of TM6SF2 E167K variant during MASLD progression are not yet fully understood.

METHODS

The Tm6sf2167K knock-in (KI) mice were subjected to high-fat diet (HFD). Hepatic lipid levels of Tm6sf2167K KI mice were detected by lipidomics analysis. Thin-layer chromatography (TLC) was used to measure the newly synthesized triglyceride (TG) and phosphatidylcholine (PC).

RESULTS

The TM6SF2 E167K variant significantly aggravated hepatic steatosis and injury in HFD-induced mice. Decreased polyunsaturated PC level and increased polyunsaturated TG level were found in liver tissue of HFD-induced Tm6sf2167K KI mice. Mechanistic studies demonstrated that the TM6SF2 E167K variant increased the interaction between TM6SF2 and PNPLA3, and impaired PNPLA3-mediated transfer of polyunsaturated fatty acids (PUFAs) from TG to PC. The TM6SF2 E167K variant increased the level of fatty acid-induced malondialdehyde and reactive oxygen species, and decreased fatty acid-downregulated cell membrane fluidity. Additionally, the TM6SF2 E167K variant decreased the level of hepatic PC containing C18:3, and dietary supplementation of PC containing C18:3 significantly attenuated the TM6SF2 E167K-induced hepatic steatosis and injury in HFD-fed mice.

CONCLUSION

The TM6SF2 E167K variant could promote its interaction with PNPLA3 and inhibit PNPLA3-mediated transfer of PUFAs from TG to PC, resulting in the hepatic steatosis and injury during MASLD progression. PC containing C18:3 could act as a potential therapeutic supplement for MASLD patients carrying the TM6SF2 E167K variant.

Steroid Hormone Biosynthesis and Dietary Related Metabolites Associated with Excessive Daytime Sleepiness

Background

Excessive daytime sleepiness (EDS) is a complex sleep problem that affects approximately 33% of the United States population. Although EDS usually occurs in conjunction with insufficient sleep, and other sleep and circadian disorders, recent studies have shown unique genetic markers and metabolic pathways underlying EDS. Here, we aimed to further elucidate the biological profile of EDS using large scale single- and pathway-level metabolomics analyses.

Methods

Metabolomics data were available for 877 metabolites in 6,071 individuals from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) and EDS was assessed using the Epworth Sleepiness Scale (ESS) questionnaire. We performed linear regression for each metabolite on continuous ESS, adjusting for demographic, lifestyle, and physiological confounders, and in sex specific groups. Subsequently, gaussian graphical modelling was performed coupled with pathway and enrichment analyses to generate a holistic interactive network of the metabolomic profile of EDS associations.

Findings

We identified seven metabolites belonging to steroids, sphingomyelin, and long chain fatty acids sub-pathways in the primary model associated with EDS, and an additional three metabolites in the male-specific analysis. The identified metabolites particularly played a role in steroid hormone biosynthesis.

Interpretation

Our findings indicate that an EDS metabolomic profile is characterized by endogenous and dietary metabolites within the steroid hormone biosynthesis pathway, with some pathways that differ by sex. Our findings identify potential pathways to target for addressing the causes or consequences of EDS and related sleep disorders.

Funding

Details regarding funding supporting this work and all studies involved are provided in the acknowledgments section.

Time-Restricted Feeding Reduces Atherosclerosis in LDLR KO Mice but Not in ApoE Knockout Mice

BACKGROUND

Dyslipidemia increases cardiovascular disease risk, the leading cause of death worldwide. Under time-restricted feeding (TRF), wherein food intake is restricted to a consistent window of <12 hours, weight gain, glucose intolerance, inflammation, dyslipidemia, and hypercholesterolemia are all reduced in mice fed an obesogenic diet. LDLR (low-density lipoprotein receptor) mutations are a major cause of familial hypercholesterolemia and early-onset cardiovascular disease.

METHODS

We subjected benchmark preclinical models, mice lacking LDLR-knockout or ApoE knockout to ad libitum feeding of an isocaloric atherogenic diet either ad libitum or 9 hours TRF for up to 13 weeks and assessed disease development, mechanism, and global changes in hepatic gene expression and plasma lipids. In a regression model, a subset of LDLR-knockout mice were ad libitum fed and then subject to TRF.

RESULTS

TRF could significantly attenuate weight gain, hypercholesterolemia, and atherosclerosis in mice lacking the LDLR-knockout mice under experimental conditions of both prevention and regression. In LDLR-knockout mice, increased hepatic expression of genes mediating β-oxidation during fasting is associated with reduced VLDL (very-low-density lipoprotein) secretion and lipid accumulation. Additionally, increased sterol catabolism coupled with fecal loss of cholesterol and bile acids contributes to the atheroprotective effect of TRF. Finally, TRF alone or combined with a cholesterol-free diet can reduce atherosclerosis in LDLR-knockout mice. However, mice lacking ApoE, which is an important protein for hepatic lipoprotein reuptake do not respond to TRF.

CONCLUSIONS

In a preclinical animal model, TRF is effective in both the prevention and regression of atherosclerosis in LDLR knockout mice. The results suggest TRF alone or in combination with a low-cholesterol diet can be a lifestyle intervention for reducing cardiovascular disease risk in humans.

Associations of childhood BMI, general and visceral fat mass with metabolite profiles at school-age

BACKGROUND

Childhood obesity increases metabolic disease risk. Underlying mechanisms remain unknown. We examined associations of body mass index (BMI), total body fat mass, and visceral fat mass with serum metabolites at school-age, and explored whether identified metabolites improved the identification of children at risk of a metabolically unhealthy phenotype.

METHODS

We performed a cross-sectional analysis among 497 children with a mean age of 9.8 (95% range 9.1, 10.6) years, participating in a population-based cohort study. We measured BMI, total body fat mass using DXA, and visceral fat mass using MRI. Serum concentrations of amino-acids, non-esterified-fatty-acids, phospholipids, and carnitines were determined using LC-MS/MS. Children were categorized as metabolically healthy or metabolically unhealthy, according to BMI, blood pressure, lipids, glucose, and insulin levels.

RESULTS

Higher BMI and total body fat mass were associated with altered concentrations of branched-chain amino-acids, essential amino-acids, and free carnitines. Higher BMI was also associated with higher concentrations of aromatic amino-acids and alkyl-lysophosphatidylcholines (FDR-corrected p-values < 0.05). The strongest associations were present for Lyso.PC.a.C14.0 and SM.a.C32.2 (FDR-corrected p-values < 0.01). Higher visceral fat mass was only associated with higher concentrations of 6 individual metabolites, particularly Lyso.PC.a.C14.0, PC.aa.C32.1, and SM.a.C32.2. We selected 15 metabolites that improved the prediction of a metabolically unhealthy phenotype, compared to BMI only (AUC: BMI: 0.59 [95% CI 0.47,0.71], BMI + Metabolites: 0.91 [95% CI 0.85,0.97]).

CONCLUSIONS

An adverse childhood body fat profile, characterized by higher BMI and total body fat mass, is associated with metabolic alterations, particularly in amino acids, phospholipids, and carnitines. Fewer associations were present for visceral fat mass. We identified a metabolite profile that improved the identification of impaired cardiometabolic health in children, compared to BMI only.

Comparison of Adiposomal Lipids between Obese and Non-Obese Individuals

Our recent findings revealed that human adipose tissues (AT)-derived extracellular vesicles (adiposomes) vary in cargo among obese and lean individuals. The main objective of this study was to investigate the adiposomal lipid profiles and their correlation with cardiometabolic risk factors. AT samples were collected from obese subjects and lean controls and analyzed for their characteristics and lipid content. In addition, we measured the correlation between adiposomal lipid profiles and body composition, glucose and lipid metabolic profiles, brachial artery vasoreactivity, AT arteriolar flow-induced dilation, and circulating markers such as IL-6, C-reactive protein, and nitric oxide (NO). Compared to lean controls, adiposomes isolated from obese subjects were higher in number after normalization to AT volume. The two major lipid classes differentially expressed were lysophosphatidylcholine/phosphatidylcholine (LPC/PC) and ceramides (Cer). All lipids in the LPC/PC class were several-fold lower in adiposomes from obese subjects compared to lean controls, on top of which were PC 18:2, PC 18:1, and PC 36:3. Most ceramides were markedly upregulated in the obese group, especially Cer d37:0, Cer d18:0, and Cer d39:0. Regression analyses revealed associations between adiposomal lipid profiles and several cardiometabolic risk factors such as body mass index (BMI), fat percentage, insulin resistance, arteriolar and brachial artery vasoreactivity, NO bioavailability, and high-density lipoproteins (HDL-C). We conclude that the ability of adiposomes from obese subjects to disrupt cardiometabolic function could be partly attributed to the dysregulated lipid cargo.

Association between PEMT rs7946 and blood pressure levels in Chinese adolescents

OBJECTIVES

This study was to explore blood pressure levels in Chinese adolescents with different genotypes of phosphatidylethanolamine N-methyltransferase (PEMT) gene ( PEMT ) rs7946, as well as effects of dietary intake on blood pressure levels with different genders and different genotypes of PEMT rs7946.

METHODS

PEMT rs7946 genotypes were identified by PCR-restriction fragment length polymorphism and verified by DNA sequencing. Blood pressure was measured using a standard mercury sphygmomanometer. Dietary intakes were analyzed based on a 3-day diet diary, and dietary components were calculated using computer software.

RESULTS

A total of 721 high school students (314 males and 407 females) at the age of 16.86 ± 0.59 years were included. The A allele carriers of PEMT rs7946 had increased levels of SBP, DBP, mean arterial pressure (MAP) and pulse pressure (PP) than the GG homozygotes in the female subjects. There were significant interactions between PEMT rs7946 and gender on SBP and MAP levels, regardless of whether an unadjusted or adjusted model was used. When dietary intake was taken into account, fat intake was positively associated with SBP and PP in the male GG homozygotes, while protein intake was positively associated with PP in the female A allele carriers of PEMT rs7946.

CONCLUSION

This study suggests that PEMT rs7946 is significantly associated with blood pressure levels in human being. There might be interactions among PEMT rs7946, gender, and dietary intake on blood pressure levels in the adolescent population.

Development of fatty liver disease model using high cholesterol and low choline diet in white leghorn chickens

Nonalcoholic fatty liver disease (NAFLD), which shows similar symptoms as fatty liver hemorrhage syndrome (FLHS) in chickens, is the most common cause of chronic liver disease and cancer in humans. NAFLD patients and FLHS in chickens have demonstrated severe liver disorders when infected by emerging strains of human hepatitis E virus (HEV) and avian HEV, respectively. We sought to develop a fatty liver disease chicken model by altering the diet of 3-week-old white leghorn chickens. The high cholesterol, and low choline (HCLC) diet included 7.6% fat with additional 2% cholesterol and 800 mg/kg choline in comparison to 5.3% fat, and 1,300 mg/kg choline in the regular diet. Our diet induced fatty liver avian model successfully recapitulates the clinical features seen during NAFLD in humans and FLHS in chickens, including hyperlipidemia and hepatic steatosis, as indicated by significantly higher serum triglycerides, serum cholesterol, liver triglycerides, cholesterol, and fatty acids. By developing this chicken model, we expect to provide a platform to explore the role of lipids in the liver pathology linked with viral infections and contribute to the development of prophylactic interventions.

New insights and potential biomarkers for intraventricular hemorrhage in extremely premature infant, case-control study

BACKGROUND

Despite advancements in neonatal care, germinal matrix-intraventricular hemorrhage impacts 20% of very preterm infants, exacerbating their neurological prognosis. Understanding its complex, multifactorial pathophysiology and rapid onset remains challenging. This study aims to link specific cord blood biomolecules at birth with post-natal germinal matrix-intraventricular hemorrhage onset.

METHODS

A monocentric, prospective case-control study was conducted at Rouen University Hospital from 2015 to 2020. Premature newborns ( < 30 gestational age) were included and cord blood was sampled in the delivery room. A retrospective matching procedure was held in 2021 to select samples for proteomic and metabolomic analysis of 370 biomolecules.

RESULTS

26 patients with germinal matrix-intraventricular hemorrhage cases and 60 controls were included. Clinical differences were minimal, except for higher invasive ventilation rates in the germinal matrix-intraventricular hemorrhage group. Germinal matrix-intraventricular hemorrhage newborns exhibited lower phosphatidylcholine levels and elevated levels of four proteins: BOC cell adhesion-associated protein, placental growth factor, Leukocyte-associated immunoglobulin-like receptor 2, and tumor necrosis factor-related apoptosis-inducing ligand receptor 2.

CONCLUSION

This study identifies biomolecules that may be linked to subsequent germinal matrix-intraventricular hemorrhage, suggesting heightened vascular disruption risk as an independent factor. These results need further validation but could serve as early germinal matrix-intraventricular hemorrhage risk biomarkers for future evaluations.

IMPACT

Decrease in certain phosphatidylcholines and increase in four proteins in cord blood at birth may be linked to subsequent germinal matrix-intraventricular hemorrhage in premature newborns. The four proteins are BOC cell adhesion-associated protein, placental growth factor, leukocyte-associated immunoglobulin-like receptor 2, and TNF-related apoptosis-inducing ligand receptor 2. This biological imprint could point toward higher vascular disruption risk as an independent risk factor for this complication and with further validations, could be used for better stratification of premature newborns at birth.

Mendelian randomization analysis identifies causal associations between serum lipidomic profile, amino acid biomarkers and sepsis

Background

Sepsis is a life-threatening condition marked by a severe systemic response to infection, leading to widespread inflammation, cellular signaling disruption, and metabolic dysregulation. The role of lipid and amino acid metabolism in sepsis is not fully understood, but aberrations in this pathway could contribute to the disease's pathophysiology.

Methods

To explore the potential of lipid and amino acid compounds as biomarkers for the diagnosis and prognosis of sepsis, a two-sample Mendelian Randomization (MR) study was conducted, examining the relationship between sepsis and 249 serum lipid and amino acid-related markers. Key enzymes involved in synthesis of phosphatidylcholine, including choline/ethanolamine phosphotransferase 1 (CEPT1), choline phosphotransferase 1 (CPT1), and ethanolamine phosphotransferase 1 (EPT1), were also targeted for drug-target Mendelian randomization.

Results

The study found that phosphatidylcholines (OR IVW: 0.88, 95%CI: 0.80-0.96, p = 0.005) and phospholipids in medium HDL (OR IVW: 0.86, 95%CI: 0.77-0.96, p = 0.007) potentially exhibit a protective effect against sepsis nominally. However, the potential drug target of CEPT1, CPT1, and EPT1 was found to be unrelated to septic outcomes.

Conclusion

Our findings suggest that increasing levels of phosphatidylcholines and medium HDL phospholipids may reduce the incidence of sepsis. This highlights the potential of lipid-based biomarkers in the diagnosis and management of sepsis, opening avenues for new therapeutic strategies.

Quantification of AICAR and study of metabolic markers after administration

Objectives: AICAR (5-amino-4-imidazolecarboxyamide ribonucleoside) was reported as the first pharmacological AMPK (adenosine 5'-monophosphate (AMP)-activated protein kinase) activator, and it has been confirmed to exhibit a significant endurance enhancement effect and prohibited for doping by the World Anti-Doping Agency. Due to the fact that the human body can produce such substances, in order to ensure fairness in sports competition, methods for rapid detection and multi-type identification of AICAR drugs taken orally should be established. Methods: to assess AICAR levels, a new rapid, sensitive, efficient, and selective method was reported for the quantitative detection of AICAR in urine using LC-MS/MS. The method was validated for quantitative purposes based on the elemental selectivity, intra- (1.0-15.6%) and inter-day precision (1.3-16.3%), accuracy (99.9-112.8%), matrix effects (88.9-103.6%), recovery (87.4-106.5%), and stability at four different concentrations. The calibration curve was linear over a wide concentration range of 10-10,000 ng mL-1 with a high coefficient of determination (R 2 > 0.998). The limit of detection (LOD) and limit of quantification (LOQ) for the experiment were determined to be 1 and 10 ng mL-1, respectively. Simultaneously, metabolomics analysis was used to obtain the metabolic fingerprint of different populations and biomarkers to distinguish administration cases through partial least squares discriminant analysis (PLS-DA) and a receiver operating characteristic (ROC) curve. Results: the method enables easy quantitation for LC-MS/MS analysis with the best recovery yield maintained, and the method was applied to 122 Asian biological samples with an average concentration of 1310.5 ± 1031.4 ng mL-1. Through drug metabolism research, 734 and 294 variables were extracted for data analysis respectively in the positive and negative ion modes, and more than 100 metabolites with significant up- and down-regulation were found after the test. Conclusions: this research developed a fast, precise, effective, and specific approach for the qualitative and quantitative identification of AICAR in urine. Meanwhile, administration metabolism studies found that there were significant changes in AICAR levels and other compounds, such as PC types PC(18:1/16:0), PC(16:0/18:0), and PC(16:0/16:0), PE types PE(18:0/20:4), and LPE-type 18:1, which could better distinguish samples before and after AICAR administration. The analysis provides a multi-perspective reference for WADA to determine a positive criterion.

PCYT1A deficiency disturbs fatty acid metabolism and induces ferroptosis in the mouse retina

BACKGROUND

Inherited retinal dystrophies (IRDs) are a group of debilitating visual disorders characterized by the progressive degeneration of photoreceptors, which ultimately lead to blindness. Among the causes of this condition, mutations in the PCYT1A gene, which encodes the rate-limiting enzyme responsible for phosphatidylcholine (PC) de novo synthesis via the Kennedy pathway, have been identified. However, the precise mechanisms underlying the association between PCYT1A mutations and IRDs remain unclear. To address this knowledge gap, we focused on elucidating the functions of PCYT1A in the retina.

RESULTS

We found that PCYT1A is highly expressed in Müller glial (MG) cells in the inner nuclear layer (INL) of the retina. Subsequently, we generated a retina-specific knockout mouse model in which the Pcyt1a gene was targeted (Pcyt1a-RKO or RKO mice) to investigate the molecular mechanisms underlying IRDs caused by PCYT1A mutations. Our findings revealed that the deletion of Pcyt1a resulted in retinal degenerative phenotypes, including reduced scotopic electroretinogram (ERG) responses and progressive degeneration of photoreceptor cells, accompanied by loss of cells in the INL. Furthermore, through proteomic and bioinformatic analyses, we identified dysregulated retinal fatty acid metabolism and activation of the ferroptosis signalling pathway in RKO mice. Importantly, we found that PCYT1A deficiency did not lead to an overall reduction in PC synthesis within the retina. Instead, this deficiency appeared to disrupt free fatty acid metabolism and ultimately trigger ferroptosis.

CONCLUSIONS

This study reveals a novel mechanism by which mutations in PCYT1A contribute to the development of IRDs, shedding light on the interplay between fatty acid metabolism and retinal degenerative diseases, and provides new insights into the treatment of IRDs.

PNPLA3 is a triglyceride lipase that mobilizes polyunsaturated fatty acids to facilitate hepatic secretion of large-sized very low-density lipoprotein

The I148M variant of PNPLA3 is closely associated with hepatic steatosis. Recent evidence indicates that the I148M mutant functions as an inhibitor of PNPLA2/ATGL-mediated lipolysis, leaving the role of wild-type PNPLA3 undefined. Despite showing a triglyceride hydrolase activity in vitro, PNPLA3 has yet to be established as a lipase in vivo. Here, we show that PNPLA3 preferentially hydrolyzes polyunsaturated triglycerides, mobilizing polyunsaturated fatty acids for phospholipid desaturation and enhancing hepatic secretion of triglyceride-rich lipoproteins. Under lipogenic conditions, mice with liver-specific knockout or acute knockdown of PNPLA3 exhibit aggravated liver steatosis and reduced plasma VLDL-triglyceride levels. Similarly, I148M-knockin mice show decreased hepatic triglyceride secretion during lipogenic stimulation. Our results highlight a specific context whereby the wild-type PNPLA3 facilitates the balance between hepatic triglyceride storage and secretion, and suggest the potential contribution of a loss-of-function by the I148M variant to the development of fatty liver disease in humans.

The effects of exposure to and timing of a choline-deficient diet during pregnancy and early postnatal life on the skeletal muscle transcriptome of the offspring

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is related to muscle loss, but the precise mechanism underlying this association remains unclear. The aim of the present study was thus to determine the influence of maternal fatty liver and dietary choline deficiency during pregnancy and/or lactation periods on the skeletal muscle gene expression profile among 24-day-old male rat offspring.

METHODS

Histological examination of skeletal muscle tissue specimens obtained from offspring of dams suffering from fatty liver, provided with proper choline intake during pregnancy and lactation (NN), fed a choline-deficient diet during both periods (DD), deprived of choline only during pregnancy (DN), or only during lactation (ND), was performed. The global transcriptome pattern was assessed using a microarray approach (Affymetrix® Rat Gene 2.1 ST Array Strip). The relative expression of selected genes was validated by real-time PCR (qPCR).

RESULTS

Morphological differences in fat accumulation in skeletal muscle related to choline supply were observed. The global gene expression profile was consistent with abnormal morphological changes. Mettl21c gene was overexpressed in all choline-deficient groups compared to the NN group, while two genes, Cdkn1a and S100a4, were downregulated. Processes of protein biosynthesis were upregulated, and processes related to cell proliferation and lipid metabolism were inhibited in DD, DN, and ND groups compared to the NN group.

CONCLUSIONS

Prenatal and early postnatal exposure to fatty liver and dietary choline deficiency leads to changes in the transcriptome profile in skeletal muscle of 24-day old male rat offspring and is associated with muscle damage, but the mechanism of it seems to be different at different developmental stages of life. Adequate choline intake during pregnancy and lactation can prevent severe muscle disturbance in the progeny of females suffering from fatty liver.

Prenatal Exposure to Chemical Mixtures and Metabolic Syndrome Risk in Children

Importance

Prenatal exposure to ubiquitous endocrine-disrupting chemicals (EDCs) may increase the risk of metabolic syndrome (MetS) in children, but few studies have studied chemical mixtures or explored underlying protein and metabolic signatures.

Objective

To investigate associations of prenatal exposure to EDC mixtures with MetS risk score in children and identify associated proteins and metabolites.

Design, Setting, and Participants

This population-based, birth cohort study used data collected between April 1, 2003, and February 26, 2016, from the Human Early Life Exposome cohort based in France, Greece, Lithuania, Norway, Spain, and the UK. Eligible participants included mother-child pairs with measured prenatal EDC exposures and complete data on childhood MetS risk factors, proteins, and metabolites. Data were analyzed between October 2022 and July 2023.

Exposures

Nine metals, 3 organochlorine pesticides, 5 polychlorinated biphenyls, 2 polybrominated diphenyl ethers (PBDEs), 5 perfluoroalkyl substances (PFAS), 10 phthalate metabolites, 3 phenols, 4 parabens, and 4 organophosphate pesticide metabolites measured in urine and blood samples collected during pregnancy.

Main Outcomes and Measures

At 6 to 11 years of age, a composite MetS risk score was constructed using z scores of waist circumference, systolic and diastolic blood pressures, triglycerides, high-density lipoprotein cholesterol, and insulin levels. Childhood levels of 44 urinary metabolites, 177 serum metabolites, and 35 plasma proteins were quantified using targeted methods. Associations were assessed using bayesian weighted quantile sum regressions applied to mixtures for each chemical group.

Results

The study included 1134 mothers (mean [SD] age at birth, 30.7 [4.9] years) and their children (mean [SD] age, 7.8 [1.5] years; 617 male children [54.4%] and 517 female children [45.6%]; mean [SD] MetS risk score, -0.1 [2.3]). MetS score increased per 1-quartile increase of the mixture for metals (β = 0.44; 95% credible interval [CrI], 0.30 to 0.59), organochlorine pesticides (β = 0.22; 95% CrI, 0.15 to 0.29), PBDEs (β = 0.17; 95% CrI, 0.06 to 0.27), and PFAS (β = 0.19; 95% CrI, 0.14 to 0.24). High-molecular weight phthalate mixtures (β = -0.07; 95% CrI, -0.10 to -0.04) and low-molecular weight phthalate mixtures (β = -0.13; 95% CrI, -0.18 to -0.08) were associated with a decreased MetS score. Most EDC mixtures were associated with elevated proinflammatory proteins, amino acids, and altered glycerophospholipids, which in turn were associated with increased MetS score.

Conclusions and Relevance

This cohort study suggests that prenatal exposure to EDC mixtures may be associated with adverse metabolic health in children. Given the pervasive nature of EDCs and the increase in MetS, these findings hold substantial public health implications.

Germ-free status but not subacute polychlorinated biphenyl (PCB) exposure altered hepatic phosphatidylcholine and ether-phosphatidylcholine levels in mice

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that pose a current ecosystem and human health concern. PCB exposure impacts the gut microbiome in animal models, suggesting a mechanistic link between PCB exposure and adverse health outcomes. The presence and absence of the microbiome and exposure to PCBs independently affect the lipid composition in the liver, which in turn affects the PCB disposition in target tissues, such as the liver. Here, we investigated microbiome × subacute PCB effects on the hepatic lipid composition of conventional and germ-free female mice exposed to 0, 6, or 30 mg/kg body weight of an environmental PCB mixture in sterile corn oil once daily for 3 consecutive days. Hepatic triacylglyceride and polar lipid levels were quantified using mass spectrometric methods following the subacute PCB exposure. The lipidomic analysis revealed no PCB effect on the hepatic levels. No microbiome effect was observed on levels of triacylglyceride and most polar lipid classes. The total hepatic levels of phosphatidylcholine (PC) and ether-phosphatidylcholine (ePC) lipids were lower in germ-free mice than the conventional mice from the same exposure group. Moreover, levels of several unsaturated PCs, such as PC(36:5) and PC(42:10), and ePCs, such as ePC(36:2) and ePC(4:2), were lower in germ-free than conventional female mice. Based on a KEGG pathway meta-analysis of RNA sequencing data, the ether lipid metabolism pathway is altered in the germ-free mouse liver. In contrast to the liver, extractable lipid levels, determined gravimetrically, differed in several tissues from naïve conventional vs. germ-free mice. Overall, microbiome × subacute PCB exposure effects on hepatic lipid composition are unlikely to affect PCB distribution into the mouse liver. Further studies are needed to assess how the different extractable lipid levels in other tissues alter PCB distribution in conventional vs. germ-free mice.

Association of adrenal steroids with metabolomic profiles in patients with primary and endocrine hypertension

Introduction

Endocrine hypertension (EHT) due to pheochromocytoma/paraganglioma (PPGL), Cushing's syndrome (CS), or primary aldosteronism (PA) is linked to a variety of metabolic alterations and comorbidities. Accordingly, patients with EHT and primary hypertension (PHT) are characterized by distinct metabolic profiles. However, it remains unclear whether the metabolomic differences relate solely to the disease-defining hormonal parameters. Therefore, our objective was to study the association of disease defining hormonal excess and concomitant adrenal steroids with metabolomic alterations in patients with EHT.

Methods

Retrospective European multicenter study of 263 patients (mean age 49 years, 50% females; 58 PHT, 69 PPGL, 37 CS, 99 PA) in whom targeted metabolomic and adrenal steroid profiling was available. The association of 13 adrenal steroids with differences in 79 metabolites between PPGL, CS, PA and PHT was examined after correction for age, sex, BMI, and presence of diabetes mellitus.

Results

After adjustment for BMI and diabetes mellitus significant association between adrenal steroids and metabolites - 18 in PPGL, 15 in CS, and 23 in PA - were revealed. In PPGL, the majority of metabolite associations were linked to catecholamine excess, whereas in PA, only one metabolite was associated with aldosterone. In contrast, cortisone (16 metabolites), cortisol (6 metabolites), and DHEA (8 metabolites) had the highest number of associated metabolites in PA. In CS, 18-hydroxycortisol significantly influenced 5 metabolites, cortisol affected 4, and cortisone, 11-deoxycortisol, and DHEA each were linked to 3 metabolites.

Discussions

Our study indicates cortisol, cortisone, and catecholamine excess are significantly associated with metabolomic variances in EHT versus PHT patients. Notably, catecholamine excess is key to PPGL's metabolomic changes, whereas in PA, other non-defining adrenal steroids mainly account for metabolomic differences. In CS, cortisol, alongside other non-defining adrenal hormones, contributes to these differences, suggesting that metabolic disorders and cardiovascular morbidity in these conditions could also be affected by various adrenal steroids.

Clot or Not? Reviewing the Reciprocal Regulation Between Lipids and Blood Clotting

Both hyperlipidemia and thrombosis contribute to the risks of atherosclerotic cardiovascular diseases, which are the leading cause of death and reduced quality of life in survivors worldwide. The accumulation of lipid-rich plaques on arterial walls eventually leads to the rupture or erosion of vulnerable lesions, triggering excessive blood clotting and leading to adverse thrombotic events. Lipoproteins are highly dynamic particles that circulate in blood, carry insoluble lipids, and are associated with proteins, many of which are involved in blood clotting. A growing body of evidence suggests a reciprocal regulatory relationship between blood clotting and lipid metabolism. In this review article, we summarize the observations that lipoproteins and lipids impact the hemostatic system, and the clotting-related proteins influence lipid metabolism. We also highlight the gaps that need to be filled in this area of research.

Radix Saposhnikoviae enhancing Huangqi Chifeng Decoction improves lipid metabolism in AS mice

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqi Chifeng decoction (HQCF) combined with parsnips is a classic Chinese traditional medicine formula that has certain advantages in the clinical treatment of cardiovascular and cerebrovascular diseases. At present, there is an absence of research on the regulatory effect and mechanism of this formula on atherosclerosis (AS). The synergistic effect of Radix Saposhnikoviae (RS) in HQCF is also unclear.

AIM OF THE STUDY

This study was designed to investigate the role of RS, which is designed as a guide drug for HQCF, in improving the lipid metabolism of AS.

MATERIALS AND METHODS

In this study, we studied the effect of HQCF on ApoE-/- mice before and after RS compatibility. Hematoxylin and eosin (HE) staining and oil red staining were used to evaluate atherosclerotic lesions and lipid accumulation in the aorta and liver, respectively. The expression of adenosine monophosphate-activated protein kinase (AMPK) and pAMPK in the aorta was measured by immunofluorescence, and AMPK and sterol regulatory element binding protein-1 (SREBP-1),fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) in liver tissue were measured by Western blot analysis. Metabolomics was used to compare the changes in serum and liver metabolites of ApoE-/- mice before and after RS combination.

RESULTS

Compared with the control group, the serum lipid levels of ApoE-/- mice increased, the aortic intima thickened with plaque formation, and liver tissue pathological changes and lipid deposition occurred. Both (HQCFT without RS)HQCS and HQCF can improve the pathological condition of tissue and regulate the blood lipid level. It was noted that HQCF could promote the phosphorylation of AMPK to activate it, inhibit the expression of SREBP-1c and FAS, reduce lipid synthesis, and inhibit ACC to promote the oxidative decomposition of fatty acids. Serum and liver metabolome results showed that HQCS and HQCF treated AS mainly by regulating glycerophospholipid metabolism, sphingolipid metabolism and the arachidonic acid metabolism pathway. Importantly, HQCF showed better efficacy in regulating lipid metabolism than the HQCS group.

CONCLUSION

HQCF decoction reduces atherosclerotic lesions in the aorta and lipid accumulation in the liver, which may regulate lipid transport and metabolic function by activating the AMPK pathway. These effects can be attributed to the guidance and synergism of RS.

A Narrative Review on Maternal Choline Intake and Liver Function of the Fetus and the Infant; Implications for Research, Policy, and Practice

Dietary choline is needed to maintain normal health, including normal liver function in adults. Fatty liver induced by a choline-deficient diet has been consistently observed in human and animal studies. The effect of insufficient choline intake on hepatic fat accumulation is specific and reversible when choline is added to the diet. Choline requirements are higher in women during pregnancy and lactation than in young non-pregnant women. We reviewed the evidence on whether choline derived from the maternal diet is necessary for maintaining normal liver function in the fetus and breastfed infants. Studies have shown that choline from the maternal diet is actively transferred to the placenta, fetal liver, and human milk. This maternal-to-child gradient can cause depletion of maternal choline stores and increase the susceptibility of the mother to fatty liver. Removing choline from the diet of pregnant rats causes fatty liver both in the mother and the fetus. The severity of fatty liver in the offspring was found to correspond to the severity of fatty liver in the respective mothers and to the duration of feeding the choline-deficient diet to the mother. The contribution of maternal choline intake in normal liver function of the offspring can be explained by the role of phosphatidylcholine in lipid transport and as a component of cell membranes and the function of choline as a methyl donor that enables synthesis of phosphatidylcholine in the liver. Additional evidence is needed on the effect of choline intake during pregnancy and lactation on health outcomes in the fetus and infant. Most pregnant and lactating women are currently not achieving the adequate intake level of choline through the diet. Therefore, public health policies are needed to ensure sufficient choline intake through adding choline to maternal multivitamin supplements.

Mechanisms of hepatic steatosis in chickens: integrated analysis of the host genome, molecular phenomics and gut microbiome

Hepatic steatosis is the initial manifestation of abnormal liver functions and often leads to liver diseases such as nonalcoholic fatty liver disease in humans and fatty liver syndrome in animals. In this study, we conducted a comprehensive analysis of a large chicken population consisting of 705 adult hens by combining host genome resequencing; liver transcriptome, proteome, and metabolome analysis; and microbial 16S ribosomal RNA gene sequencing of each gut segment. The results showed the heritability (h2 = 0.25) and duodenal microbiability (m2 = 0.26) of hepatic steatosis were relatively high, indicating a large effect of host genetics and duodenal microbiota on chicken hepatic steatosis. Individuals with hepatic steatosis had low microbiota diversity and a decreased genetic potential to process triglyceride output from hepatocytes, fatty acid β-oxidation activity, and resistance to fatty acid peroxidation. Furthermore, we revealed a molecular network linking host genomic variants (GGA6: 5.59-5.69 Mb), hepatic gene/protein expression (PEMT, phosphatidyl-ethanolamine N-methyltransferase), metabolite abundances (folate, S-adenosylmethionine, homocysteine, phosphatidyl-ethanolamine, and phosphatidylcholine), and duodenal microbes (genus Lactobacillus) to hepatic steatosis, which could provide new insights into the regulatory mechanism of fatty liver development.

Plasma lipidome reveals susceptibility and resistance of Pekin ducks to DHAV-3

Duck hepatitis A virus genotype 3 (DHAV-3) is the most popular pathogen of duck viral hepatitis (DVH) and has led to a huge economic threat to the Asian duck industry. In this work, we investigated the differences in the LC-MS/MS-based dynamic lipid profiles between susceptible and resistant Pekin duck lines with DHAV-3 infection. We found that the plasma lipidome of the two duck lines was characterized differently in expression levels of lipids during the infection, such as decreased levels of glycerolipids and increased levels of cholesteryl esters and glycerophospholipids in susceptible ducks compared with resistant ducks. By integrating lipidomics and transcriptomics analysis, we showed that the altered homeostasis of lipids was potentially regulated by a variety of differentially expressed genes including CHPT1, PI4K2A, and OSBP2 between the two duck lines, which could account for liver dysfunction, apoptosis, and illness upon DHAV-3 infection. Using the least absolute shrinkage and selection operator (LASSO) approach, we determined a total of 25 infection-related lipids that were able to distinguish between the infection states of susceptible and resistant ducks. This study provides molecular clues for elucidating the pathogenesis and therapeutic strategies of DHAV-3 infection in ducklings, which has implication for the development of resistance breeding.

Role of autophagy in betaine-promoted hepatoprotection against non-alcoholic fatty liver disease in mice

Betaine, a compound found in plants and sea foods, is known to be beneficial against non-alcoholic fatty liver disease (NAFLD), but its hepatoprotective and anti-steatogenic mechanisms have been not fully understood. In the present study, we investigated the mechanisms underlying betaine-mediated alleviation of NAFLD induced by a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) in mice, with special focus on the contribution of betaine-stimulated autophagy to NAFLD prevention. Male ICR mice were fed a CDAHFD with or without betaine (0.2-1% in drinking water) for 1 week. Betaine ameliorated the CDAHFD-induced fatty liver by restoring sulfur amino acid (SAA)-related metabolites, such as S-adenosylmethionine and homocysteine, and the phosphorylation of AMPK and ACC. In addition, it reduced the CDAHFD-induced ER stress (BiP, ATF6, and CHOP) and apoptosis (Bax, cleaved caspase-3, and cleaved PARP); however, it induced autophagy (LC3II/I and p62) which was downregulated by CDAHFD. To determine the role of autophagy in the improvement of NAFLD, chloroquine (CQ), an autophagy inhibitor, was injected into the mice fed a CDAHFD and betaine (0.5 % in drinking water). CQ did not affect SAA metabolism but reduced the beneficial effects of betaine as shown by the increases of hepatic lipids, ER stress, and apoptosis. Notably, the betaine-induced improvements in lipid metabolism determined by protein levels of p-AMPK, p-ACC, PPARα, and ACS1, were reversed by CQ. Thus, the results of this study suggest that the activation of autophagy is an important upstream mechanism for the inhibition of steatosis, ER stress, and apoptosis by betaine in NAFLD.

Gut microbiota affects the estrus return of sows by regulating the metabolism of sex steroid hormones

BACKGROUND

Sex hormones play important roles in the estrus return of post-weaning sows. Previous studies have demonstrated a complex and bi-directional regulation between sex hormones and gut microbiota. However, the extent to which the gut microbiota affects estrus return of post-weaning sows is largely unknown.

RESULTS

In this study, we first screened 207 fecal samples from well-phenotyped sows by 16S rRNA gene sequencing and identified significant associations between microbes and estrus return of post-weaning sows. Using metagenomic sequencing data from 85 fecal samples, we identified 37 bacterial species that were significantly associated with estrus return. Normally returning sows were characterized by increased abundances of L. reuteri and P. copri and decreased abundances of B. fragilis, S. suis, and B. pseudolongum. The changes in gut microbial composition significantly altered the functional capacity of steroid hormone biosynthesis in the gut microbiome. The results were confirmed in a validation cohort. Significant changes in sex steroid hormones and related compounds were found between normal and non-return sows via metabolome analysis. An integrated analysis of differential bacterial species, metagenome, and fecal metabolome provided evidence that normal return-associated bacterial species L. reuteri and Prevotella spp. participated in the degradation of pregnenolone, progesterone, and testosterone, thereby promoting estrogen biosynthesis. Furthermore, the microbial metabolites related to sow energy and nutrient supply or metabolic disorders also showed relationships with sow estrus return.

CONCLUSIONS

An integrated analysis of differentially abundant bacterial species, metagenome, and fecal metabolome revealed the involvement of L. reuteri and Prevotella spp. in sow estrus return. These findings provide deep insight into the role of gut microbiota in the estrus return of post-weaning sows and the complex cross-talk between gut microbiota and sex hormones, suggesting that the manipulation of the gut microbiota could be an effective strategy to improve sow estrus return after weaning.

Parental sex-dependent effects of either maternal or paternal eNOS deficiency on the offspring's phenotype without transmission of the parental eNOS deficiency to the offspring

Background: Preclinical animal studies and clinical studies indicate that both maternal as well as paternal genetic alterations/gene defects might affect the phenotype of the next-generation without transmissions of the affected gene. Currently, the question of whether the same genetic defect present in the mother or father leads to a similar phenotype in the offspring remains insufficiently elucidated. Methods: In this head-to-head study, we crossbred female and male mice with heterozygous endothelial eNOS knockout (eNOS+/-) with male and female wild-type (wt) mice, respectively. Subsequently, we compared the phenotype of the resulting wt offspring with that of wt offspring born to parents with no eNOS deficiency. Results: Wt female offspring of mothers with heterozygous eNOS showed elevated liver fat accumulation, while wt male offspring of fathers with heterozygous eNOS exhibited increased fasting insulin, heightened insulin levels after a glucose load, and elevated liver glycogen content. By quantitative mass-spectrometry it was shown that concentrations of six serum metabolites (lysoPhosphatidylcholine acyl C20:3, phosphatidylcholine diacyl C36:2, phosphatidylcholine diacyl C38:1, phosphatidylcholine acyl-alkyl C34:1, phosphatidylcholine acyl-alkyl C36:3, and phosphatidylcholine acyl-alkyl C42:5 (PC ae C42:5) as well as four liver carbon metabolites (fructose 6-phosphate, fructose 1,6-bisphosphate, glucose 6-phosphate and fumarate) were different between wt offspring with eNOS+/- mothers and wt offspring with eNOS+/- fathers. Importantly, fumarate was inversely correlated with the liver fat accumulation in female offspring with eNOS+/- mothers and increased liver glycogen in offspring of both sexes with eNOS+/- fathers. The qRT-PCR results revealed that the gene expression patterns were different between wt offspring with eNOS+/- mothers and those offspring with eNOS+/- fathers. Different gene expression patterns were correlated with different observed phenotypic changes in male/female offspring born to mothers or fathers with a heterozygous eNOS genotype. Conclusion: The identical parental genetic alteration (heterozygous eNOS deficiency), without being passed on to the offspring, results in distinct metabolic, liver phenotype, and gene expression pattern variations depending on whether the genetic alteration originated from the father or the mother.

Consequences of Aging on Bone

With the aging of the global population, the incidence of musculoskeletal diseases has been increasing, seriously affecting people's health. As people age, the microenvironment within skeleton favors bone resorption and inhibits bone formation, accompanied by bone marrow fat accumulation and multiple cellular senescence. Specifically, skeletal stem/stromal cells (SSCs) during aging tend to undergo adipogenesis rather than osteogenesis. Meanwhile, osteoblasts, as well as osteocytes, showed increased apoptosis, decreased quantity, and multiple functional limitations including impaired mechanical sensing, intercellular modulation, and exosome secretion. Also, the bone resorption function of macrophage-lineage cells (including osteoclasts and preosteoclasts) was significantly enhanced, as well as impaired vascularization and innervation. In this study, we systematically reviewed the effect of aging on bone and the within microenvironment (including skeletal cells as well as their intracellular structure variations, vascular structures, innervation, marrow fat distribution, and lymphatic system) caused by aging, and mechanisms of osteoimmune regulation of the bone environment in the aging state, and the causal relationship with multiple musculoskeletal diseases in addition with their potential therapeutic strategy.

Longitudinal associations between metabolites and immediate, short- and medium-term exposure to ambient air pollution: Results from the KORA cohort study

BACKGROUND

Short-term exposure to air pollution has been reported to be associated with cardiopulmonary diseases, but the underlying mechanisms remain unclear. This study aimed to investigate changes in serum metabolites associated with immediate, short- and medium-term exposures to ambient air pollution.

METHODS

We used data from the German population-based Cooperative Health Research in the Region of Augsburg (KORA) S4 survey (1999-2001) and two follow-up examinations (F4: 2006-08 and FF4: 2013-14). Mass-spectrometry-based targeted metabolomics was used to quantify metabolites among serum samples. Only participants with repeated metabolites measurements were included in this analysis. We collected daily averages of fine particles (PM2.5), coarse particles (PMcoarse), nitrogen dioxide (NO2), and ozone (O3) at urban background monitors located in Augsburg, Germany. Covariate-adjusted generalized additive mixed-effects models were used to examine the associations between immediate (2-day average of same day and previous day as individual's blood withdrawal), short- (2-week moving average), and medium-term exposures (8-week moving average) to air pollution and metabolites. We further performed pathway analysis for the metabolites significantly associated with air pollutants in each exposure window.

RESULTS

Of 9,620 observations from 4,261 study participants, we included 5,772 (60.0%) observations from 2,583 (60.6%) participants in this analysis. Out of 108 metabolites that passed quality control, multiple significant associations between metabolites and air pollutants with several exposure windows were identified at a Bonferroni corrected p-value threshold (p < 3.9 × 10-5). We found the highest number of associations for NO2, particularly at the medium-term exposure windows. Among the identified metabolic pathways based on the metabolites significantly associated with air pollutants, the glycerophospholipid metabolism was the most robust pathway in different air pollutants exposures.

CONCLUSIONS

Our study suggested that short- and medium-term exposure to air pollution might induce alterations of serum metabolites, particularly in metabolites involved in metabolic pathways related to inflammatory response and oxidative stress.

Metabolomic and lipidomic studies on the intervention of taurochenodeoxycholic acid in mice with hyperlipidemia

Bile acids are the main component of animal bile and are directly involved in the metabolic process of lipids in vivo. Taurochenodeoxycholic acid (TCDCA) is the primary biologically active substance in bile acids and has biological functions such as antioxidant, antipyretic, anti-inflammatory, and analgesic activities and improves immunity. In the present study, we assessed the impact of TCDCA on hyperlipidemia development in mouse models. Mice were fed a high-fat diet (HFD) to induce hyperlipidemia and orally administered different doses of TCDCA orally for 30 days. Then, indicators such as triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in mice were detected. Using HE and ORO staining techniques, the morphology of the mice's liver tissue was detected. Based on metabolomic and lipidomic analyses, we determined the mechanism of TCDCA in treating hyperlipidemia. The results showed that TCDCA had a significant ameliorating effect on dietary hyperlipidemia. In addition, it exerted therapeutic effects through glycerophospholipid metabolism.

Effects of temperature-humidity index on blood metabolites of German dairy cows and their female calves

Heat stress (HS) impairs productivity, health, and welfare in dairy cows, and additionally causes metabolic changes. Hence, specific metabolites could be used as HS biomarkers. Consequently, the aim of the present study was to compare blood metabolite concentrations of German Holstein dairy cows and of their female calves suffering from high temperature-humidity index (THI) during late gestation (cows) or during their first week of life (calves) or not. According to the mean daily THI (mTHI) at the day before blood sampling, animals were classified into 2 groups: high mTHI ≥60 (hmTHI) and low mTHI <60 (lmTHI). To perform a standard cross-sectional 2-group study, cow groups (n = 48) and calf groups (n = 47) were compared separately. Differences in metabolite concentrations between hmTHI and lmTHI animals were inferred based on a targeted metabolomics approach. In the first step, processed metabolomics data were evaluated by multivariate data analysis techniques, and were visualized using the web-based platform MetaboAnalyst V5.0. The most important metabolites with pronounced differences between groups were further analyzed in a second step using linear mixed models. We identified 9 thermally sensitive metabolites for the cows [dodecanedioic acid; 3-indolepropionic acid; sarcosine; triglycerides (14:0_34:0), (16:0_38:7), (18:0_32:1), and (18:0_36:2); phosphatidylcholine aa C38:1; and lysophosphatidylcholine a C20:3] and for the calves [phosphatidylcholines aa C38:1, ae C38:3, ae C36:0, and ae C36:2; cholesteryl esters (17:1) and (20:3); sphingomyelins C18:0 and C18:1; and p-cresol sulfate], most of them related to lipid metabolism. Apart from 2 metabolites (3-indolepropionic acid and sarcosine) in cows, the metabolite plasma concentrations were lower in hmTHI than in lmTHI groups. In our heat-stressed dry cows, results indicate an altered lipid metabolism compared with lactating heat-stressed cows, due to the missing antilipolytic effect of HS. The results also indicate alterations in lipid metabolism of calves due to high mTHI in the first week of life. From a cross-generation perspective, high mTHI directly before calving seems to reduce colostrum quality, with detrimental effects on metabolite concentrations in offspring.

[The lipidosis in the liver of the dairy cow: Part 2 Genetic predisposition and prophylaxis]

Hepatic lipidosis in dairy cows is the result of a disturbed balance between the uptake of non-esterified fatty acids (NEFA), their metabolism in the hepatocytes, and the limited efflux of TG as very-low-density lipoprotein (VLDL). Lipidosis and the associated risk for ketosis represents a consequence of selecting dairy cows primarily for milk production without considering the basic physiological mechanisms of this trait. The overall risk for lipidosis and ketosis possesses a genetic background and the recently released new breeding value of the German Holstein Friesian cows now sets the path for correction of this risk and in that confirms the assumed genetic threat. Ectopic fat deposition in the liver is the result of various steps including lipolysis, uptake of fat by the liver cell, its metabolism, and finally release as very-low-density lipoprotein (VLDL). These reactions may be modulated directly or indirectly and hence, serve as basis for prophylactic measures. The pertaining methods are described in order to support an improved understanding of the pathogenesis of lipidosis and ketosis. They consist of feeding a glucogenic diet, restricted feeding during the close-up time as well as supplementation with choline, niacin, carnitine, or the reduction of milking frequency. Prophylactic measures for the prevention of ketosis are also included in this discussion.

Substrate-Specific Function of PNPLA3 Facilitates Hepatic VLDL-Triglyceride Secretion During Stimulated Lipogenesis

The I148M variant of PNPLA3 is strongly linked to hepatic steatosis. Evidence suggests a gain-of-function role for the I148M mutant as an ATGL inhibitor, leaving the physiological relevance of wild-type PNPLA3 undefined. Here we show that PNPLA3 selectively degrades triglycerides (TGs) enriched in polyunsaturated fatty acids (PUFAs) independently of ATGL in cultured cells and mice. Lipidomics and metabolite tracing analyses demonstrated that PNPLA3 mobilizes PUFAs from intracellular TGs for phospholipid desaturation, supporting hepatic secretion of TG-rich lipoproteins. Consequently, mice with liver-specific knockout or acute knockdown of PNPLA3 both exhibited aggravated liver steatosis and concomitant decreases in plasma VLDL-TG, phenotypes that manifest only under lipogenic conditions. I148M-knockin mice similarly displayed impaired hepatic TG secretion during lipogenic stimulation. Our results highlight a specific context whereby PNPLA3 facilitates the balance between hepatic TG storage and secretion and suggest the potential contributions of I148M variant loss-of-function to the development of hepatic steatosis in humans.

Summary Statement

We define the physiological role of wild type PNPLA3 in maintaining hepatic VLDL-TG secretion.

High-Performance Liquid Chromatography-Mass Spectrometry-based Metabolic Profiling of Adult Growth Hormone Deficiency

CONTEXT

Patients with adult growth hormone deficiency (AGHD) are at increased risk of metabolic syndrome. Metabolic profiles in AGHD patients have been insufficiently evaluated.

OBJECTIVE

This work aims to explore serum metabolite profiles by metabolomics analysis and assess potential metabolites associated with recombinant human growth hormone (rhGH) treatment.

METHODS

Thirty-one AGHD patients and 31 healthy controls were enrolled. Untargeted ultra-performance liquid chromatography-coupled mass spectroscopy was conducted in all patients and controls at baseline and during 12 months of rhGH treatment in 11 AGHD patients. Data were processed by principal component analysis, variable importance in projection scoring, orthogonal partial least squares-discriminant analysis, and MetaboAnalyst 5.0. We further explored the associations between metabolites and clinical parameters.

RESULTS

Metabolomics indicated a distinct metabolic pattern between AGHD patients and healthy controls. The perturbed pathways mainly include the biosynthesis of unsaturated fatty acids, sphingolipid metabolism, glycerophospholipid metabolism, fatty acid elongation, degradation, and biosynthesis. rhGH treatment increased the levels of specific glycerophospholipids compounds and reduced fatty acid ester compounds. Significant correlations existed between the 40 identified metabolites and insulin-like growth factor-1 SD score (IGF-1 SDS), body composition, and glucose and lipid metabolism plasma markers. During rhGH treatment, there was a statistically significant negative correlation between deoxycholic acid glycine conjugate and waist-to-hip ratio, while a statistically significant positive correlation existed between decanoylcarnitine and serum low-density lipoprotein levels.

CONCLUSION

AGHD patients have unique metabolomic profiles. rhGH treatment alters the serum levels of several fatty acid compounds/amino acids, which may contribute to the improvement of metabolic status in AGHD patients.

Epigenetic Regulation in Lean Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), the most prominent cause of chronic liver disease worldwide, is a rapidly growing epidemic. It consists of a wide range of liver diseases, from steatosis to nonalcoholic steatohepatitis, and predisposes patients to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. NAFLD is strongly correlated with obesity; however, it has been extensively reported among lean/nonobese individuals in recent years. Although lean patients demonstrate a lower prevalence of diabetes mellitus, central obesity, dyslipidemia, hypertension, and metabolic syndrome, a percentage of these patients may develop steatohepatitis, advanced liver fibrosis, and cardiovascular disease, and have increased all-cause mortality. The pathophysiological mechanisms of lean NAFLD remain vague. Studies have reported that lean NAFLD demonstrates a close association with environmental factors, genetic predisposition, and epigenetic modifications. In this review, we aim to discuss and summarize the epigenetic mechanisms involved in lean NAFLD and to introduce the interaction between epigenetic patterns and genetic or non genetic factors. Several epigenetic mechanisms have been implicated in the regulation of lean NAFLD. These include DNA methylation, histone modifications, and noncoding-RNA-mediated gene regulation. Epigenetics is an area of special interest in the setting of lean NAFLD as it could provide new insights into the therapeutic options and noninvasive biomarkers that target this under-recognized and challenging disorder.

Experimental Models for Studying Structural and Functional State of the Pathological Liver (Review)

Liver pathologies remain one of the leading causes of mortality worldwide. Despite a high prevalence of liver diseases, the possibilities of diagnosing, prognosing, and treating non-alcoholic and alcoholic liver diseases still have a number of limitations and require the development of new methods and approaches. In laboratory studies, various models are used to reconstitute the pathological conditions of the liver, including cell cultures, spheroids, organoids, microfluidic systems, tissue slices. We reviewed the most commonly used in vivo, in vitro, and ex vivo models for studying non-alcoholic fatty liver disease and alcoholic liver disease, toxic liver injury, and fibrosis, described their advantages, limitations, and prospects for use. Great emphasis was placed on the mechanisms of development of pathological conditions in each model, as well as the assessment of the possibility of reconstructing various key aspects of pathogenesis for all these pathologies. There is currently no consensus on the choice of the most adequate model for studying liver pathology. The choice of a certain effective research model is determined by the specific purpose and objectives of the experiment.

Dietary choline, but not L-carnitine, increases circulating lipid and lipoprotein concentrations, without affecting body composition, energy expenditure or respiratory quotient in lean and obese male cats during weight maintenance

Introduction

Due to the involvement in one-carbon metabolism and lipid mobilization, choline and L-carnitine supplementation have been recommended to minimize hepatic lipid accumulation and support fat oxidation, respectively. This study investigated the lipotropic benefits of choline or L-carnitine supplementation in lean and obese cats maintaining body weight (BW).

Methods

Lean [n = 9; body condition score (BCS): 4-5/9] and obese (n = 9; BCS: 8-9/9) adult male neutered colony cats were used in a replicated 3 x 3 complete Latin square design. Treatments included choline (378 mg/kg BW0.67), L-carnitine (200 mg/kg BW) and control (no supplement). Treatments were supplemented to the food for 6 weeks each, with a 2-week washout between treatments. Cats were fed once daily to maintenance energy requirements, and BW and BCS were assessed weekly. Fasted blood collection, indirect calorimetry, and dual-energy X-ray absorptiometry occurred at the end of each treatment period. Serum was analyzed for cholesterol (CHOL), high-density lipoprotein CHOL (HDL-C), triglycerides (TAG), non-esterified fatty acids (NEFA), glucose, creatinine (CREAT), urea, alkaline phosphatase (ALP) and alanine aminotransferase (ALT). Very low-density lipoprotein CHOL (VLDL) and low-density lipoprotein CHOL (LDL-C) were calculated. Data were analyzed using proc GLIMMIX, with group and period as random effects, and treatment, body condition, and their interaction as fixed effects, followed by a Tukey's post-hoc test when significance occurred.

Results

Cats supplemented choline had lower food intake (P = 0.025). Treatment did not change BW, BCS and body composition (P > 0.05). Obese cats had greater ALP, TAG, and VLDL, and lower HDL-C compared to lean cats (P < 0.05). Choline resulted in greater CHOL, HDL-C, LDL-C and ALT (P < 0.05). L-carnitine resulted in lower CREAT (P = 0.010). Following the post-hoc test, differences between treatment means were not present for ALP (P = 0.042). No differences were found for glucose, urea or NEFA (P > 0.05). Obese cats had a lower fed respiratory quotient (RQ), regardless of treatment (P = 0.045). Treatment did not affect fed or fasted RQ and energy expenditure (P > 0.05).

Discussion

Choline appeared to increase circulating lipid and lipoprotein concentrations regardless of body condition, likely through enhanced lipid mobilization and hepatic elimination. Neither dietary choline or L-carnitine altered body composition or energy metabolism in the lean or obese cats, as compared to control.

PEMT rs7946 Polymorphism and Sex Modify the Effect of Adequate Dietary Choline Intake on the Risk of Hepatic Steatosis in Older Patients with Metabolic Disorders

In humans, PEMT rs7946 polymorphism exerts sex-specific effects on choline requirement and hepatic steatosis (HS) risk. Few studies have explored the interaction effect of the PEMT rs7946 polymorphism and sex on the effect of adequate choline intake on HS risk. In this cross-sectional study, we investigated the association between PEMT polymorphism and adequate choline intake on HS risk. We enrolled 250 older patients with metabolic disorders with (n = 152) or without (n = 98; control) ultrasonically diagnosed HS. An elevated PEMT rs7946 A allele level was associated with a lower HS risk and body mass index in both men and women. Dietary choline intake-assessed using a semiquantitative food frequency questionnaire-was associated with reduced obesity in men only (p for trend < 0.05). ROC curve analysis revealed that the cutoff value of energy-adjusted choline intake for HS diagnosis was 448 mg/day in women (AUC: 0.62; 95% CI: 0.57-0.77) and 424 mg/day in men (AUC: 0.63, 95% CI: 0.57-0.76). In women, GG genotype and high choline intake (>448 mg/day) were associated with a 79% reduction in HS risk (adjusted OR: 0.21; 95% CI: 0.05-0.82); notably, GA or AA genotype was associated with a reduced HS risk regardless of choline intake (p < 0.05). In men, GG genotype and high choline intake (>424 mg/day) were associated with a 3.7-fold increase in HS risk (OR: 3.7; 95% CI: 1.19-11.9). Further adjustments for a high-density lipoprotein level and body mass index mitigated the effect of choline intake on HS risk. Current dietary choline intake may be inadequate for minimizing HS risk in postmenopausal Taiwanese women carrying the PEMT rs7946 GG genotype. Older men consuming more than the recommended amount of choline may have an increased risk of nonalcoholic fatty liver disease; this risk is mediated by a high-density lipoprotein level and obesity.

Reprogramming of lipid metabolism in hepatocellular carcinoma resulting in downregulation of phosphatidylcholines used as potential markers for diagnosis and prediction

BACKGROUND

Aberrant methylation and metabolic perturbations may deepen our understanding of hepatocarcinogenesis and help identify novel biomarkers for diagnosing hepatocellular carcinoma (HCC). We aimed to develop an HCC model based on a multi-omics.

RESEARCH DESIGN AND METHODS

Four hundred patient samples (200 with HCC and 200 with hepatitis B virus-related liver disease (HBVLD)) were subjected to liquid chromatography-mass spectrometry and multiplex bisulfite sequencing. Integrative analysis of clinical data, CpG data, and metabolome for the 20 complete imputation datasets within a for-loopwas used to identify biomarker.

RESULTS

Totally, 1,140 metabolites were annotated, of which 125 were differentially expressed. Lipid metabolism reprogramming in HCC, resulting in phosphatidylcholines (PC) significantly downregulated, partly due to the altered mitochondrial beta-oxidation of fatty acids with diverse chain lengths. Age, sex, serum-fetoprotein levels, cg05166871,cg14171514, cg18772205, PC (O-16:0/20:3(8Z, 11Z, 14Z)), and PC (16:1(9Z)/P-18:0) were used to develop the HCC model. The model presented a good diagnostic and an acceptable predictive performance. The cumulative incidence of HCC in low- and high-risk groups of HBVLD patients were 1.19% and 21.40%, respectively (p = 0.0039).

CONCLUSIONS

PCs serve as potential plasma biomarkers and help identify patients with HBVLD at risk of HCC who should be screened for early diagnosis and intervention.

Replacement of Dietary Fishmeal with Clostridium autoethanogenum Protein on Lipidomics and Lipid Metabolism in Muscle of Pearl Gentian Grouper

Clostridium autoethanogenum protein (CAP) is an economical and alternative protein source. Here, three experimental diets were formulated with CAP replacing 0% (CAP-0), 30% (CAP-30), and 60% (CAP-60) of fishmeal to investigate the alterations of structure integrity, fatty acids profiles, and lipid metabolism in the muscle of pearl gentian grouper. With increasing levels of CAP substitution, the percentages of 16 : 0 or 18 : 0 were decreased in triglycerides (TG) and diacylglycerols (DG); 18 : 1 or 18 : 2 was increased at the sn-1 and sn-2 positions in phosphatidylethanolamines; 20 : 5n-3 was increased in TG and DG. The phosphatidylcholines (PC) (18 : 3/20 : 5), PC(22 : 6/17 : 1), and sphingomyelins (d19 : 0/24 : 4) were identified as potential lipid biomarkers between CAP treatments. The CAP-30 treatment enhanced lipolysis and lipogenesis, while the CAP-60 treatment inhibited lipogenesis. In conclusion, fishmeal replacement with CAP affected the lipid characteristics and lipid metabolism, whereas it did not affect the structural integrity and fatty acids profiles in the muscle of pearl gentian grouper.

Identification of candidate metabolite biomarkers for metabolic syndrome and its five components in population-based human cohorts

BACKGROUND

Metabolic Syndrome (MetS) is characterized by risk factors such as abdominal obesity, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), hypertension, and hyperglycemia, which contribute to the development of cardiovascular disease and type 2 diabetes. Here, we aim to identify candidate metabolite biomarkers of MetS and its associated risk factors to better understand the complex interplay of underlying signaling pathways.

METHODS

We quantified serum samples of the KORA F4 study participants (N = 2815) and analyzed 121 metabolites. Multiple regression models adjusted for clinical and lifestyle covariates were used to identify metabolites that were Bonferroni significantly associated with MetS. These findings were replicated in the SHIP-TREND-0 study (N = 988) and further analyzed for the association of replicated metabolites with the five components of MetS. Database-driven networks of the identified metabolites and their interacting enzymes were also constructed.

RESULTS

We identified and replicated 56 MetS-specific metabolites: 13 were positively associated (e.g., Val, Leu/Ile, Phe, and Tyr), and 43 were negatively associated (e.g., Gly, Ser, and 40 lipids). Moreover, the majority (89%) and minority (23%) of MetS-specific metabolites were associated with low HDL-C and hypertension, respectively. One lipid, lysoPC a C18:2, was negatively associated with MetS and all of its five components, indicating that individuals with MetS and each of the risk factors had lower concentrations of lysoPC a C18:2 compared to corresponding controls. Our metabolic networks elucidated these observations by revealing impaired catabolism of branched-chain and aromatic amino acids, as well as accelerated Gly catabolism.

CONCLUSION

Our identified candidate metabolite biomarkers are associated with the pathophysiology of MetS and its risk factors. They could facilitate the development of therapeutic strategies to prevent type 2 diabetes and cardiovascular disease. For instance, elevated levels of lysoPC a C18:2 may protect MetS and its five risk components. More in-depth studies are necessary to determine the mechanism of key metabolites in the MetS pathophysiology.

Effects of perinatal stress on the metabolites and lipids in plasma of dairy goats

Dairy goats experience metabolic stress during the peripartal period, and their ability to navigate this stage of lactation is related to the occurrence and development of metabolic diseases. Unlike dairy cows, there is a lack of comprehensive analysis of changes in the plasma profiles of peripartal dairy goats, particularly using high-throughput techniques. A subset of 9 clinically-healthy dairy goats were used from a cohort of 96 primiparous Guanzhong dairy goats (BCS, 2.75 ± 0.15). Blood samples were collected at seven time points around parturition (d 21, 14, 7 before parturition, the day of kidding, and d 7, 14, 21 postpartum), were analyzed using untargeted metabolomics and targeted lipidomics. The orthogonal partial least squares discriminant analysis model revealed a total of 31 differential metabolites including p-cresol sulfate, pyruvic acid, cholic acid, and oxoglutaric acid. The pathway enrichment analysis identified phenylalanine metabolism, aminoacyl-tRNA biosynthesis, and citrate cycle as the top three significantly-altered pathways. The Limma package identified a total of 123 differentially expressed lipids. Phosphatidylserine (PS), free fatty acids (FFA), and acylcarnitines (ACs) were significantly increased on the day of kidding, while diacylglycerols (DAG) and triacylglycerols (TAG) decreased. Ceramides (Cer) and lyso-phosphatidylinositols (LPI) were significantly increased during postpartum period, while PS, FFA, and ACs decreased postpartum and gradually returned to antepartum levels. Individual species of FFA and phosphatidylcholines (PC) were segregated based on the differences in the saturation and length of the carbon chain. Overall, this work generated the largest repository of the plasma lipidome and metabolome in dairy goats across the peripartal period, which contributed to our understanding of the multifaceted adaptations of transition dairy goats.

Rumen-protected choline and methionine during the periparturient period affect choline metabolites, amino acids, and hepatic expression of genes associated with one-carbon and lipid metabolism

Feeding supplemental choline and Met during the periparturient period can have positive effects on cow performance; however, the mechanisms by which these nutrients affect performance and metabolism are unclear. The objective of this experiment was to determine if providing rumen-protected choline, rumen-protected Met, or both during the periparturient period modifies the choline metabolitic profile of plasma and milk, plasma AA, and hepatic mRNA expression of genes associated with choline, Met, and lipid metabolism. Cows (25 primiparous, 29 multiparous) were blocked by expected calving date and parity and randomly assigned to 1 of 4 treatments: control (no rumen-protected choline or rumen-protected Met); CHO (13 g/d choline ion); MET (9 g/d DL-methionine prepartum; 13.5 g/d DL-methionine, postpartum); or CHO + MET. Treatments were applied daily as a top dress from ~21 d prepartum through 35 d in milk (DIM). On the day of treatment enrollment (d -19 ± 2 relative to calving), blood samples were collected for covariate measurements. At 7 and 14 DIM, samples of blood and milk were collected for analysis of choline metabolites, including 16 species of phosphatidylcholine (PC) and 4 species of lysophosphatidylcholine (LPC). Blood was also analyzed for AA concentrations. Liver samples collected from multiparous cows on the day of treatment enrollment and at 7 DIM were used for gene expression analysis. There was no consistent effect of CHO or MET on milk or plasma free choline, betaine, sphingomyelin, or glycerophosphocholine. However, CHO increased milk secretion of total LPC irrespective of MET for multiparous cows and in absence of MET for primiparous cows. Furthermore, CHO increased or tended to increase milk secretion of LPC 16:0, LPC 18:1, and LPC 18:0 for primi- and multiparous cows, although the response varied with MET supplementation. Feeding CHO also increased plasma concentrations of LPC 16:0 and LPC 18:1 in absence of MET for multiparous cows. Although milk secretion of total PC was unaffected, CHO and MET increased secretion of 6 and 5 individual PC species for multiparous cows, respectively. Plasma concentrations of total PC and individual PC species were unaffected by CHO or MET for multiparous cows, but MET reduced total PC and 11 PC species during wk 2 postpartum for primiparous cows. Feeding MET consistently increased plasma Met concentrations for both primi- and multiparous cows. Additionally, MET decreased plasma serine concentrations during wk 2 postpartum and increased plasma phenylalanine in absence of CHO for multiparous cows. In absence of MET, CHO tended to increase hepatic mRNA levels of betaine-homocysteine methyltransferase and phosphate cytidylyltransferase 1 choline, α, but tended to decrease expression of 3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 and peroxisome proliferator activated receptor α irrespective of MET. Although shifts in the milk and plasma PC profile were subtle and inconsistent between primi- and multiparous cows, gene expression results suggest that supplemental choline plays a probable role in promoting the cytidine diphosphate-choline and betaine-homocysteine S-methyltransferase pathways. However, interactive effects suggest that this response depends on Met availability, which may explain the inconsistent results observed among studies when supplemental choline is fed.

Phospholipids, the Masters in the Shadows during Healing after Acute Myocardial Infarction

Phospholipids are major components of cell membranes with complex structures, high heterogeneity and critical biological functions and have been used since ancient times to treat cardiovascular disease. Their importance and role were shadowed by the difficulty or incomplete available research methodology to study their biological presence and functionality. This review focuses on the current knowledge about the roles of phospholipids in the pathophysiology and therapy of cardiovascular diseases, which have been increasingly recognized. Used in singular formulation or in inclusive combinations with current drugs, phospholipids proved their positive and valuable effects not only in the protection of myocardial tissue, inflammation and fibrosis but also in angiogenesis, coagulation or cardiac regeneration more frequently in animal models as well as in human pathology. Thus, while mainly neglected by the scientific community, phospholipids present negligible side effects and could represent an ideal target for future therapeutic strategies in healing myocardial infarction. Acknowledging and understanding their mechanisms of action could offer a new perspective into novel therapeutic strategies for patients suffering an acute myocardial infarction, reducing the burden and improving the general social and economic outcome.

The effect of methylated phosphatidylethanolamine derivatives on the ionization properties of signaling phosphatidic acid

Phosphatidylethanolamine (PE) and Phosphatidylcholine (PC) are the most abundant glycerophospholipids in eukaryotic membranes. The differences in the physicochemical properties of their headgroups have contrasting modulatory effects on their interaction with intracellular macromolecules. As such, their overall impact on membrane structure and function differs significantly. Enzymatic methylation of PE's amine headgroup produces two methylated derivatives namely monomethyl PE (MMPE) and dimethyl PE (DMPE) which have physicochemical properties that generally range between that of PE and PC. Additionally, their influence on membrane properties differs from both PE and PC. Although variations in headgroup methylation have been reported to affect signaling pathways, the direct influence that these differences exert on the ionization properties of signaling phospholipids have not been investigated. Here, we briefly review membrane function and structure that are mediated by the differences in headgroup methylation between PE, MMPE, DMPE and PC. In addition, using ³¹P MAS NMR, we investigate the effect of these four phospholipids on the ionization properties of the ubiquitous signaling anionic lipid phosphatidic acid (PA). Our results show that PA's ionization properties are differentially affected by changes in phospholipid headgroup methylation. This could have important implications for PA-protein binding and hence physiological functions in cells where signaling events lead to changes in abundance of methylated PE derivatives in the membrane.

The role of maternal choline, folate and one-carbon metabolism in mediating the impact of prenatal alcohol exposure on placental and fetal development

Prenatal alcohol consumption (PAE) may be associated with a broad spectrum of impacts, ranging from no overt effects, to miscarriage, fetal growth restriction and fetal alcohol spectrum disorder. A major mechanism underlying the effects of PAE is considered to be altered DNA methylation and gene expression. Maternal nutritional status may be an important factor in determining the extent to which PAE impacts pregnancy outcomes, particularly the dietary micronutrients folate and choline because they provide methyl groups for DNA methylation via one carbon metabolism. This review summarises the roles of folate and choline in development of the blastocyst, the placenta and the fetal brain, and examines the evidence that maternal intake of these micronutrients can modify the effects of PAE on development. Studies of folate or choline deficiency have found reduced blastocyst development and implantation, reduced placental invasion, vascularisation and nutrient transport capability, impaired fetal brain development, and abnormal neurodevelopmental outcomes. PAE has been shown to reduce absorption and/or metabolism of folate and choline and to produce similar outcomes to maternal choline/folate deficiency. A few studies have demonstrated that the effects of PAE on brain development can be ameliorated by folate or choline supplementation; however, there is very limited evidence on the effects of supplementation in early pregnancy on the blastocyst and placenta. Further studies are required to support these findings and to determine optimal supplementation parameters.

Region-resolved multi-omics of the mouse eye

The eye is a complex organ consisting of multiple compartments with unique and specialized properties, and small disturbances in one eye region can result in impaired vision and blindness. Although there have been advancements in ocular research, the hierarchical molecular network in region-wide resolution, indicating the division of labor and crosstalk among different eye regions, is not yet comprehensively illuminated. Here, we present an atlas of region-resolved proteome and lipidome of mouse eye. Multiphoton microscopy-guided laser microdissection combined with in-depth label-free proteomics identifies 13,536 proteins across various mouse eye regions. Further integrative analysis of spectral imaging, label-free proteome, and imaging mass spectrometry of the lipidome and phosphoproteome reveals distinctive molecular features, including proteins and lipids of various anatomical mouse eye regions. These deposited datasets and our open proteome server integrating all information provide a valuable resource for future functional and mechanistic studies of mouse eye and ocular disease.

Glucokinase Inactivation Ameliorates Lipid Accumulation and Exerts Favorable Effects on Lipid Metabolism in Hepatocytes

Glucokinase-maturity onset diabetes of the young (GCK-MODY) is a kind of rare diabetes with low incidence of vascular complications caused by GCK gene inactivation. This study aimed to investigate the effects of GCK inactivation on hepatic lipid metabolism and inflammation, providing evidence for the cardioprotective mechanism in GCK-MODY. We enrolled GCK-MODY, type 1 and 2 diabetes patients to analyze their lipid profiles, and found that GCK-MODY individuals exhibited cardioprotective lipid profile with lower triacylglycerol and elevated HDL-c. To further explore the effects of GCK inactivation on hepatic lipid metabolism, GCK knockdown HepG2 and AML-12 cell models were established, and in vitro studies showed that GCK knockdown alleviated lipid accumulation and decreased the expression of inflammation-related genes under fatty acid treatment. Lipidomic analysis indicated that the partial inhibition of GCK altered the levels of several lipid species with decreased saturated fatty acids and glycerolipids including triacylglycerol and diacylglycerol, and increased phosphatidylcholine in HepG2 cells. The hepatic lipid metabolism altered by GCK inactivation was regulated by the enzymes involved in de novo lipogenesis, lipolysis, fatty acid β-oxidation and the Kennedy pathway. Finally, we concluded that partial inactivation of GCK exhibited beneficial effects in hepatic lipid metabolism and inflammation, which potentially underlies the protective lipid profile and low cardiovascular risks in GCK-MODY patients.