| 1. |
- Qadri, Sami, et al.
(författare)
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Heterogeneity of phosphatidylcholine metabolism in nonalcoholic fatty liver disease
- 2022
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Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 77:Suppl. 1, s. S111-S111
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: In murine models of non-alcoholic fatty liver disease (NAFLD), liver damage associates with a deficiency of phosphatidylcholines (PCs), particularly polyunsaturated PCs (PUFA-PCs). We studied whether human PC metabolism is altered by NAFLD or by the protective genetic variant in HSD17B13 (rs72613567 T > TA).Method: In 143 obese patients with a liver biopsy and genotyping for HSD17B13 rs72613567, we analysed the hepatic lipidome (UPLC-MS). As the hepatic parenchymal fat fraction (HPFF) affects apparent concentrations of amphiphilic lipids, we normalised hepatic phospholipid concentrations to fat-free liver mass. To this end, we employed a state-of-the-art deep learning image analysis method (Aiforia Technologies) to accurately quantify HPFF in liver biopsies.Results: Total unadjusted hepatic PCs correlated negatively with HPFF (rs = −0.26, P < 0.01), but this association disappeared after normalising to fat-free liver mass (rs = 0.02, P = 0.81). With increasing HPFF, concentrations of especially saturated and monounsaturated PCs significantly increased, whereas concentrations of PUFA-PCs decreased. Accordingly, the hepatic triacylglycerol composition significantly correlated with that of hepatic PCs. In carriers of the protective variant in HSD17B13, as compared to non-carriers, the hepatic lipidome was enriched in especially PUFA-PCs.Conclusion: Patients with NAFLD have a deficiency of PUFA-PCs. The protective HSD17B13 rs72613567 variant opposes these changes, increasing intrahepatic PC concentrations.
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| 2. |
- Lahelma, Mari, et al.
(författare)
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The human liver lipidome is significantly related to the lipid composition and aggregation susceptibility of low-density lipoprotein (LDL) particles
- 2022
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Ingår i: Atherosclerosis. - : Elsevier. - 0021-9150 .- 1879-1484. ; 363, s. 22-29
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: The susceptibility of low-density lipoprotein (LDL) to aggregation predicts atherosclerotic cardiovascular disease. However, causes of interindividual variation in LDL lipid composition and aggregation susceptibility remain unclear. We examined whether the lipid composition and aggregation susceptibility of LDL reflect the lipid composition of the human liver.METHODS: Liver biopsies and blood samples for isolation of LDL particles were obtained from 40 obese subjects (BMI 45.9 ± 6.1 kg/m2, age 43 ± 8 years). LDL was isolated using sequential ultracentrifugation and lipidomic analyses of liver and LDL samples were determined using ultra-high performance liquid chromatography-mass spectrometry. LDL aggregation susceptibility ex vivo was analyzed by inducing aggregation by human recombinant secretory sphingomyelinase and following aggregate formation.RESULTS: The composition (acyl carbon number and double bond count) of hepatic triglycerides, phosphatidylcholines, and sphingomyelins (SMs) was closely associated with that of LDL particles. Hepatic dihydroceramides and ceramides were positively correlated with concentrations of the corresponding SM species in LDL as well with LDL aggregation. These relationships remained statistically significant after adjustment for age, sex, and body mass index.CONCLUSIONS: Lipid composition of LDL reflects that of the human liver in obese patients. Changes in hepatic sphingolipid metabolism may contribute to interindividual variation of LDL lipid composition and susceptibility to aggregation.
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| 3. |
- Luukkonen, Panu K., et al.
(författare)
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Distinct contributions of metabolic dysfunction and genetic risk factors in the pathogenesis of non-alcoholic fatty liver disease
- 2022
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Ingår i: Journal of Hepatology. - : Elsevier BV. - 0168-8278. ; 76:3, s. 526-535
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: There is substantial inter-individual variability in the risk of non-alcoholic fatty liver disease (NAFLD). Part of which is explained by insulin resistance (IR) (‘MetComp’) and part by common modifiers of genetic risk (‘GenComp’). We examined how IR on the one hand and genetic risk on the other contribute to the pathogenesis of NAFLD. Methods: We studied 846 individuals: 492 were obese patients with liver histology and 354 were individuals who underwent intrahepatic triglyceride measurement by proton magnetic resonance spectroscopy. A genetic risk score was calculated using the number of risk alleles in PNPLA3, TM6SF2, MBOAT7, HSD17B13 and MARC1. Substrate concentrations were assessed by serum NMR metabolomics. In subsets of participants, non-esterified fatty acids (NEFAs) and their flux were assessed by D5-glycerol and hyperinsulinemic-euglycemic clamp (n = 41), and hepatic de novo lipogenesis (DNL) was measured by D2O (n = 61). Results: We found that substrate surplus (increased concentrations of 28 serum metabolites including glucose, glycolytic intermediates, and amino acids; increased NEFAs and their flux; increased DNL) characterized the ‘MetComp’. In contrast, the ‘GenComp’ was not accompanied by any substrate excess but was characterized by an increased hepatic mitochondrial redox state, as determined by serum β-hydroxybutyrate/acetoacetate ratio, and inhibition of hepatic pathways dependent on tricarboxylic acid cycle activity, such as DNL. Serum β-hydroxybutyrate/acetoacetate ratio correlated strongly with all histological features of NAFLD. IR and hepatic mitochondrial redox state conferred additive increases in histological features of NAFLD. Conclusions: These data show that the mechanisms underlying ‘Metabolic’ and ‘Genetic’ components of NAFLD are fundamentally different. These findings may have implications with respect to the diagnosis and treatment of NAFLD. Lay summary: The pathogenesis of non-alcoholic fatty liver disease can be explained in part by a metabolic component, including obesity, and in part by a genetic component. Herein, we demonstrate that the mechanisms underlying these components are fundamentally different: the metabolic component is characterized by hepatic oversupply of substrates, such as sugars, lipids and amino acids. In contrast, the genetic component is characterized by impaired hepatic mitochondrial function, making the liver less able to metabolize these substrates.
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| 4. |
- Qadri, Sami, et al.
(författare)
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Hepatic insulin resistance is the basis of bile acid dysmetabolism in non-alcoholic fatty liver disease
- 2022
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Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 77:Suppl. 1, s. S694-S695
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: Non-alcoholic fatty liver disease (NAFLD) is associated with increased circulating bile acids (BAs). It is unknown whether this reflects altered intrahepatic BA metabolism due to NAFLD or the associated insulin resistance (IR). To dissociate steatosis from IR, we compared BA metabolism in NAFLD associated with either IR or high genetic risk.Method: In 106 patients undergoing a liver biopsy, we analysed serum/liver BAs, the hepatic transcriptome (RNA-seq), and concentrations of plasma FGF-19 (marker of intestinal BA metabolism). Using HOMA-IR and a validated weighted Polygenic Risk Score (PRS) for NAFLD, we divided the patients into matched groups to compare the effects of NAFLD associated with IR (‘High HOMA-IR’ vs. ‘LowHOMA-IR’) or with high genetic risk (‘High PRS’ vs. ‘Low PRS’) on BA metabolism.Results: An untargeted analysis identified distinct clusters of patients with simultaneously increased BAs, HOMA-IR, and liver fat content. Compared to ‘Low HOMA-IR’, patients with ‘High HOMA-IR’ had significantly higher total (+57%, P = 0.011) and especially conjugated (+82%, P = 0.002) serum BAs, but unchanged hepatic BAs. Expression of the primary hepatic BA uptake transporter NTCP was down-regulated, while plasma FGF-19 was unchanged. Despite having the same degree of steatosis and NASH compared to the ‘High HOMA-IR’ group, patients with ‘High PRS’ had similar serum/liver BAs compared to those with ‘Low PRS’. Stage F3-F4 liver fibrosis independently predicted higher serum BAs.Conclusion: In NAFLD without advanced fibrosis, serum BAs are increased due to IR, which may impair hepatocellular BA uptake. Intrahepatic BAs are unchanged in NAFLD.
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| 5. |
- Qadri, Sami, et al.
(författare)
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Obesity Modifies the Performance of Fibrosis Biomarkers in Nonalcoholic Fatty Liver Disease
- 2022
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 107:5, s. e2008-e2020
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Tidskriftsartikel (refereegranskat)abstract
- Context: Guidelines recommend blood-based fibrosis biomarkers to identify advanced nonalcoholic fatty liver disease (NAFLD), which is particularly prevalent in patients with obesity. Objective: To study whether the degree of obesity affects the performance of liver fibrosis biomarkers in NAFLD. Design: Cross-sectional cohort study comparing simple fibrosis scores [Fibrosis-4 Index (FIB-4); NAFLD Fibrosis Score (NFS); aspartate aminotransferase to platelet ratio index; BARD (body mass index, aspartate-to-alanine aminotransferase ratio, diabetes); Hepamet Fibrosis Score (HFS)] and newer scores incorporating neo-epitope biomarkers PRO-C3 (ADAPT, FIBC3) or cytokeratin 18 (MACK-3). Setting: Tertiary referral center. Patients: We recruited overweight/obese patients from endocrinology (n = 307) and hepatology (n = 71) clinics undergoing a liver biopsy [median body mass index (BMI) 40.3 (interquartile range 36.0-44.7) kg/m(2)]. Additionally, we studied 859 less obese patients with biopsy-proven NAFLD to derive BMI-adjusted cutoffs for NFS. Main Outcome Measures: Biomarker area under the receiver operating characteristic (AUROC), sensitivity, specificity, and predictive values to identify histological stage >= F3 fibrosis or nonalcoholic steatohepatitis with >= F2 fibrosis [fibrotic nonalcoholic steatohepatitis (NASH)]. Results: The scores with an AUROC >= 0.85 to identify >= F3 fibrosis were ADAPT, FIB-4, FIBC3, and HFS. For fibrotic NASH, the best predictors were MACK-3 and ADAPT. The specificities of NFS, BARD, and FIBC3 deteriorated as a function of BMI. We derived and validated new cutoffs for NFS to rule in/out >= F3 fibrosis in groups with BM Is <30.0, 30.0 to 39.9, and >= 40.0 kg/m(2). This optimized its performance at all levels of BMI. Sequentially combining FIB-4 with ADAPT or FIBC3 increased specificity to diagnose >= F3 fibrosis. Conclusions: In obese patients, the best-performing fibrosis biomarkers are ADAPT and the inexpensive FIB-4, which are unaffected by BMI. The widely used NFS loses specificity in obese individuals, which may be corrected with BMI-adjusted cutoffs.
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| 6. |
- Sen, Partho, 1983-, et al.
(författare)
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Exposure to environmental contaminants is associated with altered hepatic lipid metabolism in non-alcoholic fatty liver disease
- 2022
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Ingår i: Journal of Hepatology. - : Elsevier. - 0168-8278 .- 1600-0641. ; 76:2, s. 283-293
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Tidskriftsartikel (refereegranskat)abstract
- Background & aims: Recent experimental models and epidemiological studies suggest that specific environmental contaminants (ECs) contribute to the initiation and pathology of non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms linking EC exposure with NAFLD remain poorly understood and there is no data on their impact on the human liver metabolome. Herein, we hypothesized that exposure to ECs, particularly perfluorinated alkyl substances (PFAS), impacts liver metabolism, specifically bile acid metabolism.Methods: In a well-characterized human NAFLD cohort of 105 individuals, we investigated the effects of EC exposure on liver metabolism. We characterized the liver (via biopsy) and circulating metabolomes using 4 mass spectrometry-based analytical platforms, and measured PFAS and other ECs in serum. We subsequently compared these results with an exposure study in a PPARa-humanized mouse model.Results: PFAS exposure appears associated with perturbation of key hepatic metabolic pathways previously found altered in NAFLD, particularly those related to bile acid and lipid metabolism. We identified stronger associations between the liver metabolome, chemical exposure and NAFLD-associated clinical variables (liver fat content, HOMA-IR), in females than males. Specifically, we observed PFAS-associated upregulation of bile acids, triacylglycerols and ceramides, and association between chemical exposure and dysregulated glucose metabolism in females. The murine exposure study further corroborated our findings, vis-à-vis a sex-specific association between PFAS exposure and NAFLD-associated lipid changes.Conclusions: Females may be more sensitive to the harmful impacts of PFAS. Lipid-related changes subsequent to PFAS exposure may be secondary to the interplay between PFAS and bile acid metabolism.Lay summary: There is increasing evidence that specific environmental contaminants, such as perfluorinated alkyl substances (PFAS), contribute to the progression of non-alcoholic fatty liver disease (NAFLD). However, it is poorly understood how these chemicals impact human liver metabolism. Here we show that human exposure to PFAS impacts metabolic processes associated with NAFLD, and that the effect is different in females and males.
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