Search

Abstract Background The composition of dietary fatty acids (FA) during early life may impact adult adipose tissue (AT) development. We investigated the effects of α-linolenic acid (ALA) intake during the suckling/weaning period on AT development and metabolic markers in the guinea pig (GP). Methods Newborn GP were fed a 27%-fat diet (w/w %) with high (10%-ALA group), moderate (2.4%-ALA group) or low (0.8%-ALA group) ALA content (w/w % as total FA) until they were 21 days old (d21). Then all animals were switched to a 15%-fat diet containing 2% ALA (as total FA) until 136 days of age (d136). Results ALA and docosapentaenoic acid measured in plasma triglycerides (TG) at d21 decreased with decreasing ALA intake. Total body fat mass was not different between groups at d21. Adipose tissue TG synthesis rates and proliferation rate of total adipose cells, as assessed by 2H2O labelling, were unchanged between groups at d21, while hepatic de novo lipogenesis was significantly 2-fold increased in the 0.8%-ALA group. In older GP, the 0.8%-ALA group showed a significant 15-%-increased total fat mass (d79 and d107, p < 0.01) and epididymal AT weight (d136) and tended to show higher insulinemia compared to the 10%-ALA group. In addition, proliferation rate of cells in the subcutaneous AT was higher in the 0.8%-ALA (15.2 ± 1.3% new cells/5d) than in the 10%-ALA group (8.6 ± 1.7% new cells/5d, p = 0.021) at d136. AT eicosanoid profiles were not associated with the increase of AT cell proliferation. Conclusion A low ALA intake during early postnatal life promotes an increased adiposity in the adult GP.

A combination of olanzapine and samidorphan (OLZ/SAM) received US Food and Drug Administration approval in May 2021 for the treatment of adults with schizophrenia or bipolar I disorder. OLZ/SAM provides the efficacy of olanzapine, while mitigating olanzapine-associated weight gain. This exploratory study characterized the metabolic profile of OLZ/SAM in healthy volunteers to gain mechanistic insights. Volunteers received once-daily oral 10 mg/10 mg OLZ/SAM, 10 mg olanzapine, or placebo for 21 days. Assessments included insulin sensitivity during an oral glucose tolerance test (OGTT), hyperinsulinemic-euglycemic clamp, other measures of glucose/lipid metabolism, and adverse event (AE) monitoring. Treatment effects were estimated with analysis of covariance. In total, 60 subjects were randomized (double-blind; placebo, n = 12; olanzapine, n = 24; OLZ/SAM, n = 24). Olanzapine resulted in hyperinsulinemia and reduced insulin sensitivity during an OGTT at day 19, changes not observed with OLZ/SAM or placebo. Insulin sensitivity, measured by hyperinsulinemic-euglycemic clamp, was decreased in all treatment groups relative to baseline, but this effect was greatest with olanzapine and OLZ/SAM. Although postprandial (OGTT) glucose and fasting cholesterol concentrations were similarly increased with olanzapine or OLZ/SAM, other early metabolic effects were distinct, including post-OGTT C-peptide concentrations and aspects of energy metabolism. Forty-nine subjects (81.7%) experienced at least 1 AE, most mild or moderate in severity. OLZ/SAM appeared to mitigate some of olanzapine's unfavorable postprandial metabolic effects (e.g., hyperinsulinemia, elevated C-peptide) in this exploratory study. These findings supplement the body of evidence from completed or ongoing OLZ/SAM clinical trials supporting its role in the treatment of schizophrenia and bipolar I disorder., (© 2021. The Author(s).)

BACKGROUNDHepatic de novo lipogenesis (DNL) is elevated in nonalcoholic fatty liver disease (NAFLD). Improvements in hepatic fat by dietary sugar reduction may be mediated by reduced DNL, but data are limited, especially in children. We examined the effects of 8 weeks of dietary sugar restriction on hepatic DNL in adolescents with NAFLD and correlations between DNL and other metabolic outcomes.METHODSAdolescent boys with NAFLD (n = 29) participated in an 8-week, randomized controlled trial comparing a diet low in free sugars versus their usual diet. Hepatic DNL was measured as percentage contribution to plasma triglyceride palmitate using a 7-day metabolic labeling protocol with heavy water. Hepatic fat was measured by magnetic resonance imaging-proton density fat fraction.RESULTSHepatic DNL was significantly decreased in the treatment group (from 34.6% to 24.1%) versus the control group (33.9% to 34.6%) (adjusted week 8 mean difference: -10.6% [95% CI: -19.1%, -2.0%]), which was paralleled by greater decreases in hepatic fat (25.5% to 17.9% vs. 19.5% to 18.8%) and fasting insulin (44.3 to 34.7 vs. 35.5 to 37.0 μIU/mL). Percentage change in DNL during the intervention correlated significantly with changes in free-sugar intake (r = 0.48, P = 0.011), insulin (r = 0.40, P = 0.047), and alanine aminotransferase (ALT) (r = 0.39, P = 0.049), but not hepatic fat (r = 0.13, P = 0.532).CONCLUSIONOur results suggest that dietary sugar restriction reduces hepatic DNL and fasting insulin, in addition to reductions in hepatic fat and ALT, among adolescents with NAFLD. These results are consistent with the hypothesis that hepatic DNL is a critical metabolic abnormality linking dietary sugar and NAFLD.TRIAL REGISTRYClinicalTrials.gov NCT02513121.FUNDINGThe Nutrition Science Initiative (made possible by gifts from the Laura and John Arnold Foundation, Ambrose Monell Foundation, and individual donors), the UCSD Altman Clinical and Translational Research Institute, the NIH, Children's Healthcare of Atlanta and Emory University's Children's Clinical and Translational Discovery Core, Children's Healthcare of Atlanta and Emory University Pediatric Biostatistical Core, the Georgia Clinical and Translational Science Alliance, and the NIH National Institute of Diabetes, Digestive, and Kidney Disease.

Firsocostat (FIR: previously GS-0976), a highly sensitive OATP substrate, reduces hepatic de novo lipogenesis (DNL) by inhibiting acetyl-CoA carboxylases (ACC). Measuring the pharmacodynamic (PD) efficacy of FIR on DNL provides a unique opportunity to determine optimal dosing strategies for liver-targeted OATP substrates in settings of altered OATP function. A randomized, four-way crossover drug-drug interaction study was conducted. Hepatic DNL, a marker for ACC activity, was measured in 28 healthy volunteers after reference, single dose FIR 10 mg, FIR 10 mg plus the OATP inhibitor rifampin (RIF) 300 mg i.v., or RIF 300 mg i.v. (control for DNL effect of RIF), each separated by a 7-day washout. Samples were collected for pharmacokinetic (PK) and PD assessments through 24 hours after each treatment. Hepatic DNL and its inhibition by FIR were assessed. Twenty-four subjects completed the study. All adverse events were mild. RIF alone increased hepatic DNL area under the effect curve from time of administration up to the time of the last quantifiable concentration (AUEC last ; 35.7%). Despite a 5.2-fold increase in FIR plasma exposure (area under the concentration-time curve from zero to infinity (AUC inf )) when administered with RIF, FIR alone, and FIR + RIF had the same hepatic PD effect, 37.1% and 34.9% reduction in DNL AUEC last , respectively, compared with their respective controls. These findings indicate that large decreases in OATP activity do not alter hepatic intracellular exposure (as inferred by no change in PD) for drugs that are primarily eliminated hepatically and permeability rate-limited, such as FIR. These results support PK theory that has been difficult to test and provide practical guidance on administration of liver-targeted drugs in settings of reduced OATP function., (© 2020 The Authors. Clinical Pharmacology & Therapeutics © 2020 American Society for Clinical Pharmacology and Therapeutics.)

Aims: To assess the therapeutic potential of fatty acid synthase (FASN) inhibition with FT-4101, a potent, selective, orally bioavailable, small-molecule by (a) evaluating the dose-response of single FT-4101 doses (3, 6 and 9 mg) on hepatic de novo lipogenesis (DNL) in healthy participants (Study 1) and (b) demonstrating the safety, tolerability and efficacy on hepatic steatosis after 12 weeks of FT-4101 dosing in patients with non-alcoholic fatty liver disease (NAFLD; Study 2)., Materials and Methods: In Study 1, three sequential cohorts of healthy men (n = 10/cohort) were randomized to receive a single dose of FT-4101 (n = 5/cohort) or placebo (n = 5/cohort) followed by crossover dosing after 7 days. Hepatic DNL was assessed during fructose stimulation from 13 C-acetate incorporation. In Study 2, men and women with NAFLD (n = 14) randomly received 12 weeks of intermittent once-daily dosing (four cycles of 2 weeks on-treatment, followed by 1 week off-treatment) of 3 mg FT-4101 (n = 9) or placebo (n = 5). Steady-state DNL based on deuterated water labelling, hepatic steatosis using magnetic resonance imaging-proton density fat fraction and sebum lipids and circulating biomarkers were assessed., Results: Single and repeat dosing of FT-4101 were safe and well tolerated. Single FT-4101 doses inhibited hepatic DNL dose-dependently. Twelve weeks of 3 mg FT-4101 treatment improved hepatic steatosis and inhibited hepatic DNL. Decreases in sebum sapienate content with FT-4101 at week 11 were not significant compared to placebo and rebounded at week 12. Biomarkers of liver function, glucose and lipid metabolism were unchanged., Conclusions: Inhibition of FASN with 3 mg FT-4101 safely reduces hepatic DNL and steatosis in NAFLD patients., (© 2020 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)

Context: The effect of sotagliflozin (a dual sodium-glucose cotransporter [SGLT] 2 and SGLT1 inhibitor) on intestinal glucose absorption has not been investigated in humans., Objective: To measure rate of appearance of oral glucose (RaO) using a dual glucose tracer method following standardized mixed meals taken after single sotagliflozin or canagliflozin doses., Setting: Clinical research organization., Design and Participants: In a double-blind, 3-period crossover study (NCT01916863), 24 healthy participants were randomized to 2 cohorts of 12 participants. Within each cohort, participants were randomly assigned single oral doses of either sotagliflozin 400 mg, canagliflozin 300 mg, or placebo on each of test days 1, 8, and 15. On test days, Cohort 1 had breakfast containing [6,6-2H2] glucose 0.25 hours postdose and lunch containing [1-2H1] glucose 5.25 hours postdose; Cohort 2 had breakfast containing no labeled glucose 0.25 hours postdose and lunch containing [6,6-2H2] glucose 4.25 hours postdose. All participants received a 10- to 15-hour continuous [U-13C6] glucose infusion starting 5 hours before their first [6,6-2H2] glucose-containing meal., Main Outcome: RaO, postprandial glucose (PPG), and postprandial insulin., Results: Sotagliflozin and canagliflozin decreased area under the curve (AUC)0-1 hour and/or AUC0-2 hours for RaO, PPG, and insulin after breakfast and/or the 4.25-hour postdose lunch (P < .05 versus placebo). After the 5.25-hour postdose lunch, sotagliflozin lowered RaO AUC0-1 hour and PPG AUC0-5 hours versus both placebo and canagliflozin (P < .05)., Conclusions: Sotagliflozin delayed and blunted intestinal glucose absorption after meals, resulting in lower PPG and insulin levels, likely due to prolonged local inhibition of intestinal SGLT1 that persisted for ≥5 hours after dosing., (© Endocrine Society 2019.)

Sebum plays important physiological roles in human skin. Excess sebum production contributes to the pathogenesis of acne vulgaris, and suppression of sebum production reduces acne incidence and severity. We demonstrate that sebum production in humans depends on local flux through the de novo lipogenesis (DNL) pathway within the sebocyte. About 80 to 85% of sebum palmitate (16:0) and sapienate (16:1n10) were derived from DNL, based on stable isotope labeling, much higher than the contribution of DNL to triglyceride palmitate in circulation (~20%), indicating a minor contribution by nonskin sources to sebum lipids. This dependence on local sebocyte DNL was not recapitulated in two widely used animal models of sebum production, Syrian hamsters and Göttingen minipigs. Confirming the importance of DNL for human sebum production, an acetyl-CoA carboxylase inhibitor, ACCi-1, dose-dependently suppressed DNL and blocked synthesis of fatty acids, triglycerides, and wax esters but not free sterols in human sebocytes in vitro. ACCi-1 dose-dependently suppressed facial sebum excretion by ~50% (placebo adjusted) in human individuals dosed orally for 2 weeks. Sebum triglycerides, wax esters, and free fatty acids were suppressed by ~66%, whereas non-DNL-dependent lipid species, cholesterol, and squalene were not reduced, confirming selective modulation of DNL-dependent lipids. Last, individuals with acne vulgaris exhibited increased sebum production rates relative to individuals with normal skin, with >80% of palmitate and sapienate derived from DNL. These findings highlight the importance of local sebocyte DNL for human skin sebaceous gland biology and illuminate a potentially exploitable therapeutic target for the treatment of acne vulgaris., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Extracellular microRNAs (miRNAs) are a new class of biomarkers for cellular phenotypes and disease, and are bioactive signals within intercellular communication networks. Previously, we reported that miRNAs are secreted from macrophage to high-density lipoproteins (HDL) and delivered to recipient cells to regulate gene expression. Despite the potential importance of HDL-miRNAs, regulation of HDL-miRNA export from cells has not been fully studied. Here, we report that pancreatic islets and beta cells abundantly export miR-375-3p to HDL and this process is inhibited by cellular mechanisms that promote insulin secretion. Small RNA sequencing and PCR approaches were used to quantify beta cell miRNA export to HDL. Strikingly, high glucose conditions were found to inhibit HDL-miR-375-3p export, which was dependent on extracellular calcium. Likewise, stimulation of cAMP was found to repress HDL-miR-375-3p export. Furthermore, we found that beta cell ATP-sensitive potassium channel (K ATP ) channels are required for HDL-miRNA export as chemical inhibition (tolbutamide) and global genetic knockout (Abcc8 -/- ) approaches inhibited HDL-miR-375-3p export. This process is not likely associated with cholesterol flux, as gain-of-function and loss-of-function studies for cholesterol transporters failed to alter HDL-miR-375-3p export. In conclusion, results support that pancreatic beta cells export miR-375-3p to HDL and this process is inversely regulated to insulin secretion.

Pharmacologic inhibition of acetyl-CoA carboxylase (ACC) enzymes, ACC1 and ACC2, offers an attractive therapeutic strategy for nonalcoholic fatty liver disease (NAFLD) through simultaneous inhibition of fatty acid synthesis and stimulation of fatty acid oxidation. However, the effects of ACC inhibition on hepatic mitochondrial oxidation, anaplerosis, and ketogenesis in vivo are unknown. Here, we evaluated the effect of a liver-directed allosteric inhibitor of ACC1 and ACC2 (Compound 1) on these parameters, as well as glucose and lipid metabolism, in control and diet-induced rodent models of NAFLD. Oral administration of Compound 1 preferentially inhibited ACC enzymatic activity in the liver, reduced hepatic malonyl-CoA levels, and enhanced hepatic ketogenesis by 50%. Furthermore, administration for 6 days to high-fructose-fed rats resulted in a 20% reduction in hepatic de novo lipogenesis. Importantly, long-term treatment (21 days) significantly reduced high-fat sucrose diet-induced hepatic steatosis, protein kinase C epsilon activation, and hepatic insulin resistance. ACCi treatment was associated with a significant increase in plasma triglycerides (approximately 30% to 130%, depending on the length of fasting). ACCi-mediated hypertriglyceridemia could be attributed to approximately a 15% increase in hepatic very low-density lipoprotein production and approximately a 20% reduction in triglyceride clearance by lipoprotein lipase (P ≤ 0.05). At the molecular level, these changes were associated with increases in liver X receptor/sterol response element-binding protein-1 and decreases in peroxisome proliferator-activated receptor-α target activation and could be reversed with fenofibrate co-treatment in a high-fat diet mouse model. Conclusion: Collectively, these studies warrant further investigation into the therapeutic utility of liver-directed ACC inhibition for the treatment of NAFLD and hepatic insulin resistance., (© 2018 by the American Association for the Study of Liver Diseases.)

Colesevelam is a bile acid sequestrant approved to treat both hyperlipidemia and type 2 diabetes, but the mechanism for its glucose-lowering effects is not fully understood. The aim of this study was to investigate the role of hepatic microRNAs (miRNAs) as regulators of metabolic disease and to investigate the link between the cholesterol and glucose-lowering effects of colesevelam. To quantify the impact of colesevelam treatment in rodent models of diabetes, metabolic studies were performed in Zucker diabetic fatty (ZDF) rats and db/db mice. Colesevelam treatments significantly decreased plasma glucose levels and increased glycolysis in the absence of changes to insulin levels in ZDF rats and db/db mice. High-throughput sequencing and real-time PCR were used to quantify hepatic miRNA and mRNA changes, and the cholesterol-sensitive miR-96/182/183 cluster was found to be significantly increased in livers from ZDF rats treated with colesevelam compared with vehicle controls. Inhibition of miR-182 in vivo attenuated colesevelam-mediated improvements to glycemic control in db/db mice. Hepatic expression of mediator complex subunit 1 (MED1), a nuclear receptor coactivator, was significantly decreased with colesevelam treatments in db/db mice, and MED1 was experimentally validated to be a direct target of miR-96/182/183 in humans and mice. In summary, these results support that colesevelam likely improves glycemic control through hepatic miR-182-5p, a mechanism that directly links cholesterol and glucose metabolism. NEW & NOTEWORTHY Colesevelam lowers systemic glucose levels in Zucker diabetic fatty rats and db/db mice and increases hepatic levels of the sterol response element binding protein 2-responsive microRNA cluster miR-96/182/183. Inhibition of miR-182 in vivo reverses the glucose-lowering effects of colesevelam in db/db mice. Mediator complex subunit 1 (MED1) is a novel, direct target of the miR-96/182/183 cluster in mice and humans.

Fructose feeding increases hepatic de novo lipogenesis (DNL) and is associated with nonalcoholic fatty liver disease. Little is known, however, about individual variation in susceptibility to fructose stimulation of DNL. In this three-period crossover study, 17 healthy male subjects were enrolled to evaluate the within- and between-subject variability of acute fructose feeding on hepatic fractional DNL. During each assessment, [1- 13 C 1 ]acetate was infused to measure DNL in the fasting state and during fructose feeding. Subjects randomly received a high dose of fructose (10 mg·kg fat-free mass -1 ·min -1 ) on two occasions and a low dose (5 mg·kg fat-free mass -1 ·min -1 ) on another. Fructose solutions were administered orally every 30 min for 9.5 h. Ten subjects completed all three study periods. DNL was assessed as the fractional contribution of newly synthesized palmitate into very-low-density lipoprotein triglycerides using mass isotopomer distribution analysis. Mean fasting DNL was 5.3 ± 2.8%, with significant within- and between-subject variability. DNL increased dose dependently during fructose feeding to 15 ± 2% for low- and 29 ± 2% for high-dose fructose. The DNL response to high-dose fructose was very reproducible within an individual ( r = 0.93, P < 0.001) and independent of fasting DNL. However, it was variable between individuals and significantly correlated to influx of unlabeled acetyl-CoA ( r = 0.7, P < 0.001). Unlike fasting DNL, fructose-stimulated DNL is a robust and reproducible measure of hepatic lipogenic activity for a given individual and may be a useful indicator of metabolic disease susceptibility and treatment response.

Background & Aims: The incidence of nonalcoholic steatohepatitis (NASH) is increasing. The pathophysiological mechanisms of NASH and the sequence of events leading to hepatic fibrosis are incompletely understood. The aim of this study was to gain insight into the dynamics of key molecular processes involved in NASH and to rank early markers for hepatic fibrosis., Methods: A time-course study in low-density lipoprotein-receptor knockout. Leiden mice on a high-fat diet was performed to identify the temporal dynamics of key processes contributing to NASH and fibrosis. An integrative systems biology approach was used to elucidate candidate markers linked to the active fibrosis process by combining transcriptomics, dynamic proteomics, and histopathology. The translational value of these findings were confirmed using human NASH data sets., Results: High-fat-diet feeding resulted in obesity, hyperlipidemia, insulin resistance, and NASH with fibrosis in a time-dependent manner. Temporal dynamics of key molecular processes involved in the development of NASH were identified, including lipid metabolism, inflammation, oxidative stress, and fibrosis. A data-integrative approach enabled identification of the active fibrotic process preceding histopathologic detection using a novel molecular fibrosis signature. Human studies were used to identify overlap of genes and processes and to perform a network biology-based prioritization to rank top candidate markers representing the early manifestation of fibrosis., Conclusions: An early predictive molecular signature was identified that marked the active profibrotic process before histopathologic fibrosis becomes manifest. Early detection of the onset of NASH and fibrosis enables identification of novel blood-based biomarkers to stratify patients at risk, development of new therapeutics, and help shorten (pre)clinical experimental time frames.

NDI-010976, an allosteric inhibitor of acetyl-coenzyme A carboxylases (ACC) ACC1 and ACC2, reduces hepatic de novo lipogenesis (DNL) and favorably affects steatosis, inflammation, and fibrosis in animal models of fatty liver disease. This study was a randomized, double-blind, placebo-controlled, crossover trial evaluating the pharmacodynamic effects of a single oral dose of NDI-010976 on hepatic DNL in overweight and/or obese but otherwise healthy adult male subjects. Subjects were randomized to receive either NDI-010976 (20, 50, or 200 mg) or matching placebo in period 1, followed by the alternate treatment in period 2; and hepatic lipogenesis was stimulated with oral fructose administration. Fractional DNL was quantified by infusing a stable isotope tracer, [1- 13 C]acetate, and monitoring 13 C incorporation into palmitate of circulating very low-density lipoprotein triglyceride. Single-dose administration of NDI-010976 was well tolerated at doses up to and including 200 mg. Fructose administration over a 10-hour period stimulated hepatic fractional DNL an average of 30.9 ± 6.7% (mean ± standard deviation) above fasting DNL values in placebo-treated subjects. Subjects administered single doses of NDI-010976 at 20, 50, or 200 mg had significant inhibition of DNL compared to placebo (mean inhibition relative to placebo was 70%, 85%, and 104%, respectively). An inverse relationship between fractional DNL and NDI-010976 exposure was observed with >90% inhibition of fractional DNL associated with plasma concentrations of NDI-010976 >4 ng/mL., Conclusion: ACC inhibition with a single dose of NDI-010976 is well tolerated and results in a profound dose-dependent inhibition of hepatic DNL in overweight adult male subjects. Therefore, NDI-010976 could contribute considerable value to the treatment algorithm of metabolic disorders characterized by dysregulated fatty acid metabolism, including nonalcoholic steatohepatitis. (Hepatology 2017;66:324-334)., (© 2017 Nimbus Discovery, Inc. Hepatology published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.)

Background & Aims: The factors that distinguish metabolically healthy obesity from metabolically unhealthy obesity are not well understood. Diet has been implicated as a determinant of the unhealthy obesity phenotype, but which aspects of the diet induce dysmetabolism are unknown. The goal of this study was to investigate whether specific macronutrients or macronutrient combinations provoke dysmetabolism in the context of isocaloric, high-energy diets., Methods: Mice were fed 4 high-energy diets identical in calorie and nutrient content but different in nutrient composition for 3 weeks to 6 months. The test diets contained 42% carbohydrate (sucrose or starch) and 42% fat (oleate or palmitate). Weight and glucose tolerance were monitored; blood and tissues were collected for histology, gene expression, and immunophenotyping., Results: Mice gained weight on all 4 test diets but differed significantly in other metabolic outcomes. Animals fed the starch-oleate diet developed more severe hepatic steatosis than those on other formulas. Stable isotope incorporation showed that the excess hepatic steatosis in starch-oleate-fed mice derived from exaggerated adipose tissue lipolysis. In these mice, adipose tissue lipolysis coincided with adipocyte necrosis and inflammation. Notably, the liver and adipose tissue abnormalities provoked by starch-oleate feeding were reproduced when mice were fed a mixed-nutrient Western diet with 42% carbohydrate and 42% fat., Conclusions: The macronutrient composition of the diet exerts a significant influence on metabolic outcome, independent of calories and nutrient proportions. Starch-oleate appears to cause hepatic steatosis by inducing progressive adipose tissue injury. Starch-oleate phenocopies the effect of a Western diet; consequently, it may provide clues to the mechanism whereby specific nutrients cause metabolically unhealthy obesity.

Excess collagen synthesis (fibrogenesis) in the liver plays a causal role in the progression of nonalcoholic fatty liver disease (NAFLD). Methods are needed to identify patients with more rapidly progressing disease and to demonstrate early response to treatment. We describe here a novel method to quantify hepatic fibrogenesis flux rates both directly in liver tissue and noninvasively in blood. Twenty-one patients with suspected NAFLD ingested heavy water ( 2 H 2 O, 50-mL aliquots) two to three times daily for 3-5 weeks prior to a clinically indicated liver biopsy. Liver collagen fractional synthesis rate (FSR) and plasma lumican FSR were measured based on 2 H labeling using tandem mass spectrometry. Patients were classified by histology for fibrosis stage (F0-F4) and as having nonalcoholic fatty liver or nonalcoholic steatohepatitis (NASH). Magnetic resonance elastography measurements of liver stiffness were also performed. Hepatic collagen FSR in NAFLD increased with advancing disease stage (e.g., higher in NASH than nonalcoholic fatty liver, positive correlation with fibrosis score and liver stiffness) and correlated with hemoglobin A1C. In addition, plasma lumican FSR demonstrated a significant correlation with hepatic collagen FSR., Conclusion: Using a well-characterized cohort of patients with biopsy-proven NAFLD, this study demonstrates that hepatic scar in NASH is actively remodeled even in advanced fibrosis, a disease that is generally regarded as static and slowly progressive. Moreover, hepatic collagen FSR correlates with established risks for fibrotic disease progression in NASH, and plasma lumican FSR correlates with hepatic collagen FSR, suggesting applications as direct or surrogate markers, respectively, of hepatic fibrogenesis in humans. (Hepatology 2017;65:78-88)., (© 2016 The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.)

Diets containing excess carbohydrate and fat promote hepatic steatosis and steatohepatitis in mice. Little is known, however, about the impact of specific carbohydrate/fat combinations on liver outcome. This study was designed to determine whether high-energy diets with identical caloric density but different carbohydrate and fat composition have unique effects on the liver. Four experimental diets were formulated with 60%kcal carbohydrate and 20%kcal fat, each in nearly pure form from a single source: starch-oleate, starch-palmitate, sucrose-oleate and sucrose-palmitate. The diets were fed to mice for 3 or 12 weeks for analysis of lipid metabolism and liver injury. All mice developed hepatic steatosis over 12 weeks, but mice fed the sucrose-palmitate diet accumulated more hepatic lipid than those in the other three experimental groups. The exaggerated lipid accumulation in sucrose-palmitate-fed mice was attributable to a disproportionate rise in hepatic de novo lipogenesis. These mice accrued more hepatic palmitate and exhibited more evidence of liver injury than any of the other experimental groups. Interestingly, lipogenic gene expression in mice fed the custom diets did not correlate with actual de novo lipogenesis. In addition, de novo lipogenesis rose in all mice between 3 and 12 weeks, without feedback inhibition from hepatic steatosis. The pairing of simple sugar (sucrose) and saturated fat (palmitate) in a high-carbohydrate/moderate-fat diet induces more de novo lipogenesis and liver injury than other carbohydrate/fat combinations. Diet-induced liver injury correlates positively with hepatic de novo lipogenesis and is not predictable by isolated analysis of lipogenic gene expression., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA). Systemic inflammation is proposed to play a fundamental role in the altered lipid metabolism associated with RA; however, the underlying mechanisms are unknown. We undertook this study to compare cholesterol and lipoprotein kinetics in patients with active RA with those in matched healthy volunteers., Methods: This was a phase I open-label mechanism-of-action study. Cholesterol and lipoprotein kinetics were assessed with (13) C-cholesterol and (13) C-leucine infusions. RA patients were reevaluated after receiving oral tofacitinib 10 mg twice daily for 6 weeks., Results: Levels of high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total cholesterol, and apolipoprotein A-I (Apo A-I) as well as HDL cholesterol particle number were lower in RA patients (n = 36) than in healthy volunteers (n = 33). In contrast, the cholesterol ester fractional catabolic rate was higher in RA patients, but no differences were observed in cholesterol ester transfer protein, cholesterol ester production rate, HDL-associated Apo A-I fractional catabolic rate, or LDL-associated Apo B fractional catabolic rate. Following tofacitinib treatment in RA patients, the cholesterol ester fractional catabolic rate decreased and cholesterol levels increased. The decrease in cholesterol ester fractional catabolic rate correlated significantly with the increase in HDL cholesterol. Additionally, HDL cholesterol particle number increased and markers of HDL cholesterol function improved., Conclusion: This is the first study to assess cholesterol and lipoprotein kinetics in patients with active RA and matched healthy volunteers. The data suggest that low cholesterol levels in patients with active RA may be driven by increases in cholesterol ester catabolism. Tofacitinib treatment reduced cholesterol ester catabolism, thereby increasing cholesterol levels toward those in healthy volunteers, and markers of antiatherogenic HDL function improved., (© 2015 The Authors. Arthritis & Rheumatology is published by Wiley Periodicals, Inc. on behalf of the American College of Rheumatology.)

Acetyl-CoA carboxylase (ACC) inhibitors offer significant potential for the treatment of type 2 diabetes mellitus (T2DM), hepatic steatosis, and cancer. However, the identification of tool compounds suitable to test the hypothesis in human trials has been challenging. An advanced series of spirocyclic ketone-containing ACC inhibitors recently reported by Pfizer were metabolized in vivo by ketone reduction, which complicated human pharmacology projections. We disclose that this metabolic reduction can be greatly attenuated through introduction of steric hindrance adjacent to the ketone carbonyl. Incorporation of weakly basic functionality improved solubility and led to the identification of 9 as a clinical candidate for the treatment of T2DM. Phase I clinical studies demonstrated dose-proportional increases in exposure, single-dose inhibition of de novo lipogenesis (DNL), and changes in indirect calorimetry consistent with increased whole-body fatty acid oxidation. This demonstration of target engagement validates the use of compound 9 to evaluate the role of DNL in human disease.

MicroRNAs (miRNAs) have emerged as biomarkers of metabolic status, etiological factors in complex disease, and promising drug targets. Recent reports suggest that miRNAs are critical regulators of pathways underlying the pathophysiology of type 2 diabetes. In this study, we demonstrate by deep sequencing and real-time quantitative PCR that hepatic levels of Foxa2 mRNA and miR-29 are elevated in a mouse model of diet-induced insulin resistance. We also show that Foxa2 and miR-29 are significantly upregulated in the livers of Zucker diabetic fatty (fa/fa) rats and that the levels of both returned to normal upon treatment with the insulin-sensitizing agent pioglitazone. We present evidence that miR-29 expression in human hepatoma cells is controlled in part by FOXA2, which is known to play a critical role in hepatic energy homeostasis. Moreover, we demonstrate that miR-29 fine-tunes FOXA2-mediated activation of key lipid metabolism genes, including PPARGC1A, HMGCS2, and ABHD5. These results suggest that miR-29 is an important regulatory factor in normal metabolism and may represent a novel therapeutic target in type 2 diabetes and related metabolic syndromes., (© 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

The purpose of this study was to evaluate the variability of subcutaneous abdominal adipose tissue (AT) dynamics in obese subjects with a wide range of insulin sensitivity (IS) and the correlation between these two metabolic measures. Ten obese (BMI 30-40 kg/m²) nondiabetic subjects with (n = 6) and without (n = 4) the metabolic syndrome were studied following a 12-wk ²H₂O labeling period. Subcutaneous abdominal AT biopsies were collected. Deuterium incorporation into triglyceride (TG)-glycerol and TG-palmitate were measured by gas chromatography-mass spectrometry for the calculation of fractional TG synthesis (fTG) and fractional de novo lipogenesis (fDNL). Muscle IS and insulin-mediated nonesterified fatty acid (NEFA) suppression (a measure for adipose IS) indexes were derived from the oral glucose tolerance test (OGTT). The ability of subcutaneous abdominal AT to synthesize lipids varied significantly in obese subjects (fTG range 7-28%, fDNL range 1.1-4.6%) with significantly lower values (>35% reduction) for both parameters in obese with the metabolic syndrome. fTG correlated positively with muscle IS (r = 0.64, P = 0.04) and inversely with NEFA suppression during the OGTT (r = -0.69, P = 0.03). These results demonstrate a large variability in subcutaneous abdominal AT lipid turnover in obesity. Moreover, a reduced capacity for subcutaneous abdominal AT fat storage is associated with muscle and adipose tissue insulin resistance as well as with the metabolic syndrome, thus identifying a form of obesity at heightened risk for type 2 diabetes and cardiovascular disease.

Background: Consumption of sugar-sweetened beverages has been shown to be associated with dyslipidemia, insulin resistance, fatty liver, diabetes, and cardiovascular disease. It has been proposed that adverse metabolic effects of chronic consumption of sugar-sweetened beverages are a consequence of increased circulating glucose and insulin excursions, ie, dietary glycemic index (GI)., Objective: We determined whether the greater adverse effects of fructose than of glucose consumption were associated with glucose and insulin exposures., Design: The subjects were studied in a metabolic facility and consumed energy-balanced diets containing 55% of energy as complex carbohydrate for 2 wk (GI = 64). The subjects then consumed 25% of energy requirements as fructose- or glucose-sweetened beverages along with their usual ad libitum diets for 8 wk at home and then as part of energy-balanced diets for 2 wk at the metabolic facility (fructose GI = 38, glucose GI = 83). The 24-h glucose and insulin profiles and fasting plasma glycated albumin and fructosamine concentrations were measured 0, 2, 8, and 10 wk after beverage consumption., Results: Consumption of fructose-sweetened beverages lowered glucose and insulin postmeal peaks and the 23-h area under the curve compared with the baseline diet and with the consumption of glucose-sweetened beverages (all P < 0.001, effect of sugar). Plasma glycated albumin concentrations were lower 10 wk after fructose than after glucose consumption (P < 0.01, effect of sugar), whereas fructosamine concentrations did not differ between groups., Conclusion: The results suggest that the specific effects of fructose, but not of glucose and insulin excursions, contribute to the adverse effects of consuming sugar-sweetened beverages on lipids and insulin sensitivity. This study is registered at clinicaltrials.gov as NCT01165853.

Methionine-choline-deficient (MCD) diets cause steatohepatitis in rodents and are used to study the pathophysiology of fatty liver disease in human beings. The most widely used commercial MCD formulas not only lack methionine and choline but also contain excess sucrose and fat. The objective of this study was to determine whether dietary sucrose in the MCD formula plays a role in the pathogenesis of MCD-related liver disease. We prepared two custom MCD formulas, one containing sucrose as the principal carbohydrate and the other substituting sucrose with starch. Mice fed the sucrose-enriched formula developed typical features of MCD-related liver disease, including hepatic steatosis, hepatocellular apoptosis, alanine aminotransferase elevation, lipid peroxidation, and hepatic inflammation. In contrast, mice fed MCD-starch were significantly protected against liver injury. MCD-sucrose and MCD-starch mice displayed identical diet-related abnormalities in hepatic fatty acid uptake and triglyceride secretion. Hepatic de novo lipogenesis and triglyceride synthesis, however, were 2 times higher in MCD-sucrose mice than MCD-starch mice (P < 0.01). Hepatic lipid analysis revealed accumulation of excess saturated fatty acids in MCD-sucrose mice that correlated with hepatocellular injury. Overall, the results indicate that dietary sucrose is critical to the pathogenesis of MCD-mediated steatohepatitis. They suggest that saturated fatty acids, which are products of de novo lipogenesis, are mediators of hepatic toxicity in this model of liver disease.

Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance. To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks. Although both groups exhibited similar weight gain during the intervention, visceral adipose volume was significantly increased only in subjects consuming fructose. Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption. In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle-triglyceride and -cholesterol significantly increased during fructose but not glucose consumption. In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose. These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults.

Adipose tissue development undergoes remodeling in terms of newly synthesized cells (hyperplasia) and newly synthesized lipids that accumulate in adipocytes (hypertrophy). Synthesis and/or breakdown rates of adipose cells and lipids follow a continuous and dynamic pattern, e.g., during obesity development. This chapter describes a unique in vivo method to measure the dynamics of adipose tissue growth using 2H2O labeling and mass spectrometry analyses. The approach uses 2H2O as a metabolic tracer to label the adipose tissue components such as the triglycerides (TG), the fatty acids, and the genomic DNA. Deuterium from 2H2O incorporates in the C-H bonds of glycerol moiety of TG through glyceroneogenesis as well as in palmitate moiety through de novo lipogenesis (DNL). Deuterium also incorporates into DNA through the de novo nucleoside synthesis pathway. The labeled water, 2H2O, is administrated intraperitoneally and/or orally in rodents or in humans for a defined duration and biopsies are collected at the end of the labeling period. We describe the procedure to extract, isolate, and purify the adipose components (TG-glycerol, TG-palmitate, and genomic DNA) and the derivation procedure to analyze the isotopic 2H-enrichment of these components by gas chromatography/mass spectrometry. The calculation principles are described to obtain the fractional and absolute synthesis rates of TG, of DNL, and of DNA measured in the adipose tissues. The method is nonradioactive, nonhazardous, accurate, reproducible, and very sensitive. We present recent in vivo data on the ontogeny of adipose tissue growth dynamics in young and adult obese Zucker rats compared with lean Zucker rats.

Treatment of type 2 diabetes mellitus (T2DM) patients with pioglitazone results in a more favorable lipid profile, and perhaps more favorable cardiac outcomes, than treatment with rosiglitazone. Pioglitazone treatment increases VLDL-triacylglycerol clearance, but the role of de novo lipogenesis (DNL) has not been explored, and no direct comparison has been made between the thiazolidinediones (TZDs). Twelve subjects with T2DM and hypertriacylglyceridemia were randomized to either rosiglitazone or pioglitazone treatment. Stable isotope infusion studies were performed at baseline and after 20 weeks of treatment. Both treatments reduced glucose and HbA(1c) concentrations equally. Pioglitazone treatment resulted in a 40% reduction in hepatic DNL (P < 0.01) and in a 25% reduction in hepatic glucose production (P < 0.05), while rosiglitazone did not significantly change either parameter, although comparisons of changes between treatments were not significantly different. These pilot results indicate that pioglitazone reduces hepatic DNL while rosiglitazone does not. Larger follow-up studies are required to confirm differential effects of these agents definitively. The reduction in DNL may underlie altered assembly or atherogenicity of lipoprotein particles and may reflect PPARalpha or other non-PPARgamma actions on the liver by pioglitazone. These differences might help explain previously reported differences in lipid profiles and cardiovascular disease outcomes for rosiglitazone and pioglitazone.

Objective: The purpose of this study was to compare an in vivo test of whole-body glycolysis, the deuterated-glucose disposal test (2H-GDT), with insulin sensitivity measured by the euglycemic-hyperinsulinemic glucose clamp and the steady-state plasma glucose (SSPG) test., Research Design and Methods: The 2H-GDT consists of an oral glucose challenge containing deuterated glucose, followed by measurement of heavy water (2H2O) production, which represents whole-body glycolytic disposal of the glucose load. 2H2O production is corrected for ambient insulin concentration as an index of tissue insulin sensitivity. The 2H-GDT was compared with euglycemic-hyperinsulinemic glucose clamps in healthy lean subjects (n = 8) and subjects with the metabolic syndrome (n = 9) and with the SSPG test in overweight (n = 12) and obese (n = 6) subjects., Results: A strong correlation with the clamp was observed for the 75-g and 30-g 2H-GDT (r = 0.95, P < 0.0001 and r = 0.88, P < 0.0001, respectively). The 2H-GDT and clamp studies revealed marked insulin resistance in subjects with metabolic syndrome compared with lean control subjects. The correlation with the clamp was maintained in each group (lean, r = 0.86, P < 0.01; metabolic syndrome, r = 0.81, P < 0.01) for the 75-g test. The 2H-GDT also correlated strongly with the SSPG test (r = -0.87, P < 0.0001) in overweight and obese subjects., Conclusions: The 2H-GDT, which measures whole-body glycolysis in humans in a quantitative manner, correlates highly with the euglycemic-hyperinsulinemic glucose clamp and the SSPG test. Impaired insulin-mediated whole-body glycolysis is a feature of insulin resistance, which provides a means of assessing insulin sensitivity in vivo.

This study reports a novel protocol to increase plasma monounsaturated, polyunsaturated, and saturated nonesterified fatty acids (NEFA) in eight healthy volunteers (age 29-54 yr, body mass index 23-26 kg/m(2)). This was achieved by feeding small boluses of fat at different time points (35 g at 0 min and 8 g at 30, 60, 90, 120, 150, 180, and 210 min) in combination with a continuous low-dose heparin infusion. Olive oil, safflower oil, or palm stearin were used to increase monounsaturated, polyunsaturated, or saturated NEFAs, respectively. Plasma NEFA concentrations were increased for 2 h, when fat and heparin were given (olive oil: 745 +/- 35 micromol/l; safflower oil: 609 +/- 37 micromol/l, and palm stearin: 773 +/- 38 micromol/l) compared with the control test (no fat and no heparin: 445 +/- 41 micromol/l). During the heparin infusion, 18:1 n-9 was the most abundant fatty acid for the olive oil test compared with 18:2 n-6 for the safflower oil test and 16:0 for the palm stearin test (P < 0.01). The method described here successfully increases several types of plasma NEFA concentrations and could be used to investigate differential effects of elevated individual NEFAs on metabolic processes.

Background: The fatty acid composition of adipose tissue triacylglycerol reflects, but is not identical to, the fatty acid composition of the habitual diet., Objective: We investigated whether the fatty acid composition of adipose tissue is explained by differences between fatty acids in early storage in adipose tissue after a meal., Design: Nine healthy men ate a meal containing several fatty acids. Blood samples were taken for 6 h after the meal from an arterialized hand vein and a vein draining the anterior abdominal subcutaneous adipose tissue., Results: Net storage of fatty acids in adipose tissue occurred between 1 and 4 h after the meal. In relation to the amount fed, storage of fatty acids differed (P < 0. 01) between classes (n-3 polyunsaturated < saturated < n-6 polyunsaturated < monounsaturated); oleic acid was stored in the greatest amounts. These differences agreed closely with published data, except for n-3 polyunsaturated fatty acids. The only individual metabolic step at which significant differences between fatty acids was shown was incorporation of fatty acids into chylomicron triacylglycerol. Differences between fatty acids in rate of extraction from chylomicron triacylglycerol and net uptake into adipose tissue in the postprandial period were significant (P < 0. 01), but not when expressed in relation to proportions in chylomicron triacylglycerol., Conclusions: The characteristic fatty acid pattern of adipose tissue may predominantly reflect the early metabolic handling of different fatty acids. Adipose tissue uptake of n-3 polyunsaturated fatty acids is slow in relation to that of other fatty acids.