BACKGROUND:Gut microbiota dysbiosis is associated with the development of non-alcoholic steatohepatitis (NASH) through modulation of gut barrier, inflammation, lipid metabolism, bile acid signaling and short-chain fatty acid production. The aim of this study was to describe the impact of a choline-deficient amino acid defined high fat diet (CDAHFD) on the gut microbiota in a male Göttingen Minipig model and on selected pathways implicated in the development of NASH.RESULTS:Eight weeks of CDAHFD resulted in a significantly altered colon microbiota mainly driven by the bacterial families Lachnospiraceae and Enterobacteriaceae, being decreased and increased in relative abundance, respectively. Metabolomics analysis revealed that CDAHFD decreased colon content of short-chain fatty acid and increased colonic pH. In addition, serum levels of the microbially produced metabolite imidazole propionate were significantly elevated as a consequence of CDAHFD feeding. Hepatic gene expression analysis showed upregulation of mechanistic target of rapamycin (mTOR) and Ras Homolog, MTORC1 binding in addition to downregulation of insulin receptor substrate 1, insulin receptor substrate 2 and the glucagon receptor in CDAHFD fed minipigs. Further, the consequences of CDAHFD feeding were associated with increased levels of circulating cholesterol, bile acids, and glucagon but not total amino acids.CONCLUSIONS:Our results indicate imidazole propionate as a new potentially relevant factor in relation to NASH and discuss the possible implication of gut microbiota dysbiosis in the development of NASH. In addition, the study emphasizes the need for considering the gut microbiota and its products when developing translational animal models for NASH.

Nonalcoholic fatty liver disease (NAFLD) is an increasingly prevalent disease that is associated with multiple metabolic disturbances, yet the metabolic pathways underlying its progression are poorly understood. Here we studied metabolic pathways of the human liver across the full histological spectrum of NAFLD. We analyzed whole liver tissue transcriptomics and serum metabolomics data obtained from a large, prospectively enrolled cohort of 206 histologically characterized patients derived from the European NAFLD Registry and developed genome-scale metabolic models (GEMs) of human hepatocytes at different stages of NAFLD. We identified several metabolic signatures in the liver and blood of these patients, specifically highlighting the alteration of vitamins (A, E) and glycosphingolipids, and their link with complex glycosaminoglycans in advanced fibrosis. Furthermore, we derived GEMs and identified metabolic signatures of three common NAFLD-associated gene variants (PNPLA3, TM6SF2 and HSD17B13) . The study demonstrates dysregulated liver metabolic pathways which may contribute to the progression of NAFLD.

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) is a progressive liver disease with potentially severe complications including cirrhosis and hepatocellular carcinoma. Previously, we have identified circulating lipid signatures associating with liver fat content and non-alcoholic steatohepatitis (NASH). Here, we develop a metabolomic map across the NAFLD spectrum, defining interconnected metabolic signatures of steatosis (non-alcoholic fatty liver, NASH, and fibrosis). Methods: We performed mass spectrometry analysis of molecular lipids and polar metabolites in serum samples from the European NAFLD Registry patients (n = 627), representing the full spectrum of NAFLD. Using various univariate, multivariate, and machine learning statistical approaches, we interrogated metabolites across 3 clinical perspectives: steatosis, NASH, and fibrosis. Results: Following generation of the NAFLD metabolic network, we identify 15 metabolites unique to steatosis, 18 to NASH, and 15 to fibrosis, with 27 common to all. We identified that progression from F2 to F3 fibrosis coincides with a key pathophysiological transition point in disease natural history, with n = 73 metabolites altered. Conclusions: Analysis of circulating metabolites provides important insights into the metabolic changes during NAFLD progression, revealing metabolic signatures across the NAFLD spectrum and features that are specific to NAFL, NASH, and fibrosis. The F2-F3 transition marks a critical metabolic transition point in NAFLD pathogenesis, with the data pointing to the pathophysiological importance of metabolic stress and specifically oxidative stress. Clinical Trials registration: The study is registered at Clinicaltrials.gov (NCT04442334). Lay summary: Non-alcoholic fatty liver disease is characterised by the build-up of fat in the liver, which progresses to liver dysfunction, scarring, and irreversible liver failure, and is markedly increasing in its prevalence worldwide. Here, we measured lipids and other small molecules (metabolites) in the blood with the aim of providing a comprehensive molecular overview of fat build-up, liver fibrosis, and diagnosed severity. We identify a key metabolic 'watershed' in the progression of liver damage, separating severe disease from mild, and show that specific lipid and metabolite profiles can help distinguish and/or define these cases. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of European Association for the Study of the Liver (EASL). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

In the last decade, increasing incidence of type 1 diabetes (T1D) stabilized in Finland, a phenomenon that coincides with tighter regulation of perfluoroalkyl substances (PFAS). Here, we quantified PFAS to examine their effects, during pregnancy, on lipid and immune-related markers of T1D risk in children. In a mother-infant cohort (264 dyads), high PFAS exposure during pregnancy associated with decreased cord serum phospholipids and progression to T1D-associated islet autoantibodies in the offspring. This PFAS-lipid association appears exacerbated by increased human leukocyte antigen-conferred risk of T1D in infants. Exposure to a single PFAS compound or a mixture of organic pollutants in non-obese diabetic mice resulted in a lipid profile characterized by a similar decrease in phospholipids, a marked increase of lithocholic acid, and accelerated insulitis. Our findings suggest that PFAS exposure during pregnancy contributes to risk and pathogenesis of T1D in offspring.

Faecal microbiota transfer (FMT) consists of the infusion of donor faecal material into the intestine of a patient with the aim to restore a disturbed gut microbiota. In this study, it was investigated whether FMT has an effect on faecal microbial composition, its functional capacity, faecal metabolite profiles and their interactions in 16 irritable bowel syndrome (IBS) patients. Faecal samples from eight different time points before and until six months after allogenic FMT (faecal material from a healthy donor) as well as autologous FMT (own faecal material) were analysed by 16S RNA gene amplicon sequencing and gas chromatography coupled to mass spectrometry (GS-MS). The results showed that the allogenic FMT resulted in alterations in the microbial composition that were detectable up to six months, whereas after autologous FMT this was not the case. Similar results were found for the functional profiles, which were predicted from the phylogenetic sequencing data. While both allogenic FMT as well as autologous FMT did not have an effect on the faecal metabolites measured in this study, correlations between the microbial composition and the metabolites showed that the microbe-metabolite interactions seemed to be disrupted after allogenic FMT compared to autologous FMT. This shows that FMT can lead to altered interactions between the gut microbiota and its metabolites in IBS patients. Further research should investigate if and how this affects efficacy of FMT treatments.

Perfluorooctanesulfonate (PFOS) is a well-known contaminant in the environment and it has shown to disrupt multiple biological pathways, particularly those related with lipid metabolism. In this study, we have studied the impact of in ovo exposure to PFOS on lipid metabolism in livers in developing chicken embryos using lipidomics for detailed characterization of the liver lipidome. We used an avian model (Gallus gallus domesticus) for in ovo treatment at two levels of PFOS. The lipid profile of the liver of the embryo was investigated by ultra-high performance liquid chromatography combined with quadrupole-time-of-flight mass spectrometry and by gas chromatography mass spectrometry. Over 170 lipids were identified, covering phospholipids, ceramides, di- and triacylglycerols, cholesterol esters and fatty acid composition of the lipids. The PFOS exposure caused dose dependent changes in the lipid levels, which included upregulation of specific phospholipids associated with the phosphatidylethanolamine N-methyltransferase (PEMT) pathway, triacylglycerols with low carbon number and double bond count as well as of lipotoxic ceramides and diacylglycerols. Our data suggest that at lower levels of exposure, mitochondrial fatty acid β-oxidation is suppressed while the peroxisomal fatty acid β -oxidation is increased. At higher doses, however, both β -oxidation pathways are upregulated.

Faecal microbiota transfer in irritable bowel syndrome results inaltered correlations between the gut microbiota and its metabolites

Abstract Background Psychotic patients are at high risk for developing obesity, metabolic syndrome and type 2 diabetes. These metabolic co-morbidities are hypothesized to be related to both treatment side-effects as well as to metabolic changes occurring during the psychosis. Earlier metabolomics studies have shown that blood metabolite levels are predictive of insulin resistance and type 2 diabetes in the general population as well as sensitive to the effects of antipsychotics. Here we aimed to identify the metabolite profiles predicting future weight gain and other metabolic abnormalities in psychotic patients. Methods We applied metabolomics to investigate serum metabolite profiles in a prospective study setting in 36 first-episode psychosis patients during the first year of the antipsychotic treatment and 19 controls. Two analytical platforms with broad analytical coverage were used. Molecular lipids were analysed by ultra-high performance liquid chromatography coupled to time-of-flight mass spectrometry (UHPLC_QTOFMS) and polar metabolites were analysed by two-dimensional gas chromatography coupled to TOFMS (GCxGC-TOFMS). Ongoing prospective metabolomics studies ae focusing on the subjects in at-risk mental state. Results While corroborating several earlier findings when comparing cases and controls and the effects of the antipsychotic medication, we also found that prospective weight gain in psychotic patients was associated with increased levels of triacylglycerols with low carbon number and double-bond count at baseline and independent of obesity, that is, lipids known to be associated with increased liver fat. Discussion The first-episode psychotic patients who rapidly gain weight in the follow-up have early metabolic disturbances which are associated with insulin resistance and fatty liver. Our studies suggest that metabolite profiles may be used to identify the psychotic patients most vulnerable to develop metabolic co-morbidities, and may point to a pharmacological approach to counteract the antipsychotic-induced weight gain.

A validated method using an atmospheric pressure chemical ionization source for coupling gas chromatography (GC-APCI) to tandem quadrupole mass spectrometry (MS/MS) for the determination of brominated flame retardants (BFRs) is presented. Polybrominated diphenyl ethers (PBDEs), their methoxylated derivatives (MeO-PBDEs) and other emerging BFRs were included in this study. The method showed good linearity and repeatability. The relative standard deviation (RSD) of the relative response factors (RRFs) of all compounds was below 16%. Repeatability for BFRs was tested on one or two concentration levels of calibration standards with RSDs for RRFs below 16%. The lowest calibration standards (0.075–0.1pg/µL for emerging BFRs, BDE 209 and MeO-PBDEs mixtures, 0.625–6.25pg/µL for Br1–9 PBDEs mixtures) were used as instrument detection limits (IDL). The method was applied on biotic samples, including fish, osprey, and seal. In general, BDE 209 and decabromodiphenyl ethane (DBDPE) were detected in 50% of the seal samples. A 100% detection rate was achieved for 6-MeO-BDE 47 in all the samples (72–580pg/g ww in osprey samples, 24,000–96,000pg/g ww in seal samples and 78–99pg/g ww in fish samples). All Br3–6 PBDEs (BDE 28, 47, 99, 100, 153, 154) were detected in all the samples (ranging from 12 to 20,000pg/g ww), while BDE 183 was detected in 60% of the osprey eggs, 20% of the seal samples and below MDL in all fish samples. The results presented indicate the capability of the GC-APCI-MS/MS system for the detection and quantification of BFRs.

Temporal trends of persistent organochlorine and bromine compounds in ringed seals from the Baltic Sea (Phoca hispida baltica) from year 1974 to 2015

A method using a novel atmospheric pressure chemical ionization source for coupling gas chromatography (GC/APCI) to triple quadrupole mass spectrometry (MS/MS) for the determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) regulated by the Stockholm Convention is presented. One microliter injection of a six-point calibration curve of native PCBs and OCPs, ranging from 0.04 to 300pg/μL, was performed. The relative standard deviation (RSD) of the relative response factors (RRFs) was less than 15% with a coefficient of determination (r(2))>0.995. Meanwhile, two calibration solutions (CS), CS 2 (0.4pg/μL) and CS 3 (4pg/μL) were analyzed to study the repeatability calculated for both area and RRFs. The RSD for RRF ranged from 3.1 to 16% and 3.6 to 5.5% for CS 2 and CS 3, respectively. The limits of detection (LOD) determined by peak-to-peak signal-to-noise ratio (S/N) of 3 were compared between the GC/APCI/MS/MS and a GC coupled to high resolution mass spectrometry (GC/HRMS) system. GC/APCI/MS/MS resulted in lower LOD for most of the compounds, except for PCB#74, cis-chlordane and trans-chlordane. GC/APCI/MS/MS and GC/HRMS were also compared by performing analysis on 75 human serum samples together with eight QA/QC serum samples. The comparison between GC/APCI/MS/MS system and GC/HRMS system for 16 of the targeted compounds was carried out. No statistically significant difference was discovered. Due to increased sensitivity and user friendly operation under atmospheric pressure, GC/APCI/MS/MS is a powerful alternative technique that can easily meet the specification of GC/HRMS.

The recent developments and improvements of instrumental methods for the analyses of the environmental contaminants, especially the persistent organic pollutants (POPs), have made it possible to de ...

Temporal Trends of Polychlorinated Biphenyls, Organochlorine Pesticides and Polybrominated Diphenyl Ethers in Osprey Eggs in Sweden over the Years 1966 – 2013

■ ■ Excellent agreement with existing GC-EI-HRMS results. IN T RO DU C T IO N The term dioxins refers to a group of chemically similar congeners, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), known to persist in the environment and pose significant toxicological concern. Therefore, they are well regulated and testing is enforced globally. Testing has been traditionally performed by GC-EI-HRMS. However, recent technological advances have allowed for a revision of the analytical criteria. Following extensive review, the European Commission has enacted Regulation 589/2014, which permits the use of GC-MS/MS for the confirmatory analysis of dioxins in food and feed.

Analysis of the brominated flame retardant hexabromocyclododecane (HBCDD) is characterized by the separation of its three predominant diastereomers.