Free Fatty Acid Uptake Research Articles

Evaluation of Circulating Fatty Acid Synthase as a Biomarker in Non-Alcoholic Fatty Liver Disease

Background: The liver is the corner stone in lipid metabolism, free fatty acid uptake, synthesizing, storing and exporting lipids; non-alcoholic fatty liver disease (NAFLD) develops if there is any interruption or derangements in lipid metabolim. Fatty acid synthase (FAS) is the major enzyme in lipogenesis, and its circulating level is a bi-omarker of metabolically demanding human diseases. Aim of the Work: To evaluate the level of circulating FAS in NAFLD patients and to correlate it to serum lipid pa-rameters. Materials and Methods: The study included forty NAFLD patients and forty age and sex-matched healthy subjects as controls. Results: FAS levels were signifi-cantly higher in NAFLD patients compared to their level in the controls (P

Different Predictors of Right and Left Ventricular Metabolism in Healthy Middle-Aged Men.

Dysfunction of the right ventricle (RV) plays a crucial role in the outcome of various cardiovascular diseases. Previous studies on RV metabolism are sparse although evidence implies it may differ from left ventricular (LV) metabolism. Therefore, the aims of this study were (1) to determine predictors of RV glucose uptake (GU) and free fatty acid uptake (FFAU) and (2) to compare them to predictors of LV metabolism in healthy middle-aged men. Altogether 28 healthy, sedentary, middle-aged (40–55 years) men were studied. Insulin-stimulated GU and fasting FFAU were measured by positron emission tomography and RV and LV structural and functional parameters by cardiac magnetic resonance. Several parameters related to whole-body health were also measured. Predictors of RV and LV metabolism were determined by pairwise correlation analysis, lasso regression models, and variable clustering using heatmap. RVGU was most strongly predicted by age and moderately by RV ejection fraction (EF). The strongest determinants of RVFFAU were exercise capacity (peak oxygen uptake), resting heart rate, LVEF, and whole-body insulin-stimulated glucose uptake rate. When considering LV metabolism, age and RVEF were associated also with LVGU. In addition, LVGU was strongly, and negatively, influenced by whole-body insulin-stimulated glucose uptake rate. LVFFAU was predicted only by LVEF. This study shows that while RV and LV metabolism have shared characteristics, they also have unique properties. Age of the subject should be taken into account when measuring myocardial glucose utilization. Ejection fraction is related to myocardial metabolism, and even so that RVEF may be more closely related to GU of both ventricles and LVEF to FFAU of both ventricles, a finding supporting the ventricular interdependence. However, only RV fatty acid utilization associates with exercise capacity so that better physical fitness in a relatively sedentary population is related with decreased RV fat metabolism. To conclude, this study highlights the need for further study designed specifically on less-known RV, as the results on LV metabolism and physiology may not be directly applicable to the RV.

Hepatocyte-Specific Disruption of CD36 Attenuates Fatty Liver and Improves Insulin Sensitivity in HFD-Fed Mice.

CD36/FAT (fatty acid translocase) is associated with human and murine nonalcoholic fatty liver disease, but it has been unclear whether it is simply a marker or whether it directly contributes to disease pathogenesis. Mice with hepatocyte-specific deletion of Janus kinase 2 (JAK2L mice) have increased circulating free fatty acids (FAs), dramatically increased hepatic CD36 expression and profound fatty liver. To investigate the role of elevated CD36 in the development of fatty liver, we studied two models of hepatic steatosis, a genetic model (JAK2L mice) and a high-fat diet (HFD)-induced steatosis model. We deleted Cd36 specifically in hepatocytes of JAK2L mice to generate double knockouts and from wild-type mice to generate CD36L single-knockout mice. Hepatic Cd36 disruption in JAK2L livers significantly improved steatosis by lowering triglyceride, diacylglycerol, and cholesterol ester content. The largest differences in liver triglycerides were in species comprised of oleic acid (C18:1). Reduction in liver lipids correlated with an improvement in the inflammatory markers that were elevated in JAK2L mice, namely aspartate aminotransferase and alanine transaminase. Cd36 deletion in mice on HFD (CD36L-HFD) reduced liver lipid content and decreased hepatic 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-FA uptake as compared with CON-HFD. Additionally, CD36L-HFD mice had improved whole-body insulin sensitivity and reduced liver and serum inflammatory markers. Therefore, CD36 directly contributes to development of fatty liver under conditions of elevated free FAs by modulating the rate of FA uptake by hepatocytes. In HFD-fed animals, disruption of hepatic Cd36 protects against associated systemic inflammation and insulin resistance.

Direct incorporation of fatty acids into microbial phospholipids in soils: Position-specific labeling tells the story

Fatty acids have been used as plant and microbial biomarkers, and knowledge about their transformation pathways in soils and sediments is crucial for interpreting fatty acid signatures, especially because the formation, recycling and decomposition processes are concurrent. We analyzed the incorporation of free fatty acids into microbial fatty acids in soil by coupling position-specific 13C labeling with compound-specific 13C analysis.Position-specifically and uniformly 13C labeled palmitate were applied in an agricultural Luvisol. Pathways of fatty acids were traced by analyzing microbial utilization of 13C from individual molecule positions of palmitate and their incorporation into phospholipid fatty acids (PLFA).The fate of palmitate 13C in the soil was characterized by the main pathways of microbial fatty acid metabolism: Odd positions (C-1) were preferentially oxidized to CO2 in the citric acid cycle, whereas even positions (C-2) were preferentially incorporated into microbial biomass. This pattern is a result of palmitate cleavage to acetyl-CoA and its further use in the main pathways of C metabolism. We observed a direct, intact incorporation of more than 4% of the added palmitate into the PLFA of microbial cell membranes, indicating the important role of palmitate as direct precursor for microbial fatty acids. Palmitate 13C was incorporated into PLFA as intact alkyl chain, i.e. the C backbone of palmitate was not cleaved, but palmitate was incorporated either intact or modified (e.g. desaturated, elongated or branched) according to the fatty acid demand of the microbial community. These modifications of the incorporated palmitate increased with time. Future PLFA studies must therefore consider the recycling of existing plant and microbial-derived fatty acids.This study demonstrates the intact uptake and recycling of free fatty acids such as palmitate in soils, as well as the high turnover and transformation of cellular PLFA. Knowledge about the intact uptake and use of soil-derived free fatty acids is crucial for interpreting microbial fatty acid fingerprints and their isotopic composition.

Elevated free fatty acid uptake via CD36 promotes epithelial-mesenchymal transition in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second-leading cause of cancer-related death worldwide, and the factors influencing HCC progression are poorly understood. Here we reveal that HCC progression via induction of epithelial-mesenchymal transition (EMT) is closely associated with the expression of CD36/fatty acid translocase and elevated free fatty acid (FFA) levels. Although obesity is manifested as elevated FFA levels, the degree of EMT was not associated with the body mass index of the patients, highlighting the specific roles of CD36 and FFA uptake. Treatment of human liver cancer cell lines with FFAs exacerbated the EMT phenotype, whereas chemical inhibition of CD36 mitigated these effects. Furthermore, the Wnt and TGF-β signaling pathways were activated upon FFA treatment, potentially acting as upstream activators of the EMT program. These results provide the first direct evidence associating CD36 and elevated FFAs with HCC progression.

Abstract 5157: Elevated uptake of free fatty acids via CD36 promotes epithelial-mesenchymal transition in hepatocellular carcinoma

Abstract Hepatocellular carcinoma (HCC) is the third-leading cause of cancer-related death worldwide. The liver is the main site of free fatty acid (FFA) metabolism; epidemiological studies link HCC tumorigenesis and elevated mortality rates to obesity, which manifests as increased FFA. Previous studies investigated the cytotoxic and pro-inflammatory effects of FFA, but did not focus on its influence on HCC progression. In this study, we hypothesized that elevated FFA levels and altered cellular fatty acid uptake promote the epithelial-mesenchymal transition (EMT) program, facilitating a metastatic, invasive HCC phenotype. We investigated the association between obesity, EMT progression and alterations in FFA-transport proteins in TCGA HCC gene expression data and validated the results in protein samples from human HCC tumors. In order to scrutinize the phenotypic effects of elevated FFA, we assessed the migratory and invasive ability of HCC cell lines treated with various FFAs, and further verified the expression of EMT markers using qPCR, confocal microscopy and flow cytometry. Bioinformatic analysis of TCGA data revealed that obese patients have higher levels of CD36, a trans-membrane protein that facilitates FFA transport into the cell. CD36 expression levels were strongly correlated with an EMT gene signature. However, the degree of EMT itself was not associated with the body mass index (BMI) of the patients. These results were corroborated in protein measurements from human HCC tumor samples. Additionally, we observed that saturated and monounsaturated FFA-treated HCC cell lines exhibited increased migration, invasion, dissociation, and development of the characteristic EMT morphology. Next, we confirmed the expression of EMT markers using qPCR and confocal imaging, demonstrating that chemical inhibition of CD36 reversed the FFA-induced EMT phenotype. Given the known cytotoxic effects of elevated FFAs on hepatocytes, we tested a population-distribution hypothesis using flow cytometry. We found that although some cells succumbed to the cytotoxic effects of high FFA, a distinct population not only evaded cell death, but also acquired EMT. We further utilized PCR arrays to determine that Wnt and TGF-beta signaling pathways, potential drivers of the EMT program, were activated upon FFA treatment and showed that repression of these pathways prevented migration and invasion in FFA treated cells. Our research demonstrates the role of CD36 and FFAs in activating the EMT program via induction of Wnt and TGF-beta signaling, and provides the first direct evidence that elevated FFA uptake promotes progression of HCC through EMT. Altered CD36 and FFA levels may thus serve as prognostic biomarkers for advanced HCC and further elucidation of this program may also provide insights into role of elevated FFA in establishing a conducive environment for secondary hepatic metastases. Citation Format: Aritro Nath, Irene Li, Christina Chan. Elevated uptake of free fatty acids via CD36 promotes epithelial-mesenchymal transition in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5157. doi:10.1158/1538-7445.AM2015-5157

Ursolic acid increases energy expenditure through enhancing free fatty acid uptake and β-oxidation via an UCP3/AMPK-dependent pathway in skeletal muscle.

Ursolic acid (UA) is a triterpenoid compound with multifold biological functions. Our previous studies have reported that UA protects against high-fat diet-induced obesity and improves insulin resistance (IR). However, the potential mechanisms are still undefined. Free fatty acid (FFA) metabolism in skeletal muscle plays a central role in obesity and IR. Therefore, in this study, we investigated the effect and the potential mechanisms of UA on skeletal muscle FFA metabolism. In diet-induced obese rats, 0.5% UA supplementation for 6 weeks markedly reduced body weight, increased energy expenditure, decreased FFA level in serum and skeletal muscle and triglyceride content in skeletal muscle. In vitro, the data provided directly evidence that UA significantly increased fluorescently labeled FFA uptake and (3) H-labeled palmitic acid β-oxidation. UA-activated AMP-activated protein kinase (AMPK) and downstream targets were involved in the increase of FFA catabolism. Moreover, upregulated uncoupling protein 3 (UCP3) by UA contributed to AMPK activation via elevating adenosine monophosphate/adenosine triphosphate ratio. UA increases FFA burning through enhancing skeletal muscle FFA uptake and β-oxidation via an UCP3/AMPK-dependent pathway, which provides a novel perspective on the biological function of UA against obesity and IR.

Innovative therapeutic approaches for the treatment of myocardial ischemia and angina

Cardiac energy metabolism is complex and has three main components: 1. Substrate utilisation, 2 Oxydative phosphorilation and 3. Transfer of high energy phosphates. Substrate utilization involves the cellular uptake of free fatty acids, glucose and amino acids, their breakdown by beta-oxidation and glycolysis, and the entry of Acetyl Coenzyme A into the Krebs cycle. Oxidative phosphorylation involves the production of energy by the mitochondrial respiratory chain and the production of high-energy phosphates. Until recent it was not known that it was possible to delimitate the infarct size through therapeutic interventions. Likely, the improvement to understand the mechanisms of cellular survivor occurs in that year, when Murry et al. discovered an intrinsic mechanism of myocardial protection, which they denominated as ischemic preconditioning. In that experiment, it was observed that four cycles of five minutes of ischemia, with intermittent reperfusion, before 40 min of ischemia period, resulted in reduction of 75% of the infarct size. Also, it was demonstrated by these researches that this protection it was not resulted by collateral overture and that protective effect of the ischemic preconditioning was abolished in the presence of prolonged ischemia, with duration of 3 h. Two phenomenons, the walk-through angina and the warm up phenomenon could represent a clinical manifestation of preconditioning. The phenomenon of walk-through angina was first related in the end of century XVIII in a patient that developed angina during the effort, but experimented the paradox disappearing of the pain with the exercise continuation. The exact molecular mechanisms involved in ischemic preconditioning are not fully elucidated. Therefore, due to the high prevalence of risk factors to cardiovascular diseases and the high morbidity and mortality associated with coronary artery disease, there is a needed to understand even better the cardiac metabolism during ischemia and the strategies to reduce the consequences of the ischemia, to preserve the viability of the ischemic myocardium.

Adipose Tissue Free Fatty Acid Storage In Vivo: Effects of Insulin Versus Niacin as a Control for Suppression of Lipolysis.

Insulin stimulates the translocation fatty acid transport protein 1 (FATP1) to plasma membrane, and thus greater free fatty acid (FFA) uptake, in adipocyte cell models. Whether insulin stimulates greater FFA clearance into adipose tissue in vivo is unknown. We tested this hypothesis by comparing direct FFA storage in subcutaneous adipose tissue during insulin versus niacin-medicated suppression of lipolysis. We measured direct FFA storage in abdominal and femoral subcutaneous fat in 10 and 11 adults, respectively, during euglycemic hyperinsulinemia or after oral niacin to suppress FFA compared with 11 saline control experiments. Direct palmitate storage was assessed using a [U-13C]palmitate infusion to measure palmitate kinetics and an intravenous palmitate radiotracer bolus/timed biopsy. Plasma palmitate concentrations and flux were suppressed to 23 ± 3 and 26 ± 5 µmol ⋅ L−1 (P = 0.91) and 44 ± 4 and 39 ± 5 µmol ⋅ min−1 (P = 0.41) in the insulin and niacin groups, respectively, much less (P < 0.001) than the saline control group (102 ± 8 and 104 ± 12 µmol ⋅ min−1, respectively). In the insulin, niacin, and saline groups, abdominal palmitate storage rates were 0.25 ± 0.05 vs. 0.25 ± 0.07 vs. 0.32 ± 0.05 µmol ⋅ kg adipose lipid−1 ⋅ min−1, respectively (P = NS), and femoral adipose storage rates were 0.19 ± 0.06 vs. 0.20 ± 0.05 vs. 0.31 ± 0.05 µmol ⋅ kg adipose lipid−1 ⋅ min−1, respectively (P = NS). In conclusion, insulin does not increase FFA storage in adipose tissue compared with niacin, which suppresses lipolysis via a different pathway.

Unacylated Ghrelin Protects Hearts of Mice Subjected to Myocardial Ischemia/Reperfusion

ObjectiveGhrelin can be found in the circulation under two different forms: acylated ghrelin (AG) and unacylated ghrelin (UAG). UAG, while being the predominant ghrelin isoform in circulation, is devoid of endocrine activity. Despite its inability to activate the classical ghrelin receptor, some studies have shown that UAG possesses cardiotropic properties. Our aim is to investigate the cardioprotective effects of UAG against myocardial ischemia‐reperfusion (MI/R) injury.MethodsC57BL/6 mice were pretreated twice a day for 14 days with either AG or UAG at 200 nmol/kg/day. Myocardial ischemia was induced by the ligature of left anterior descending coronary artery for 30 min, followed by reperfusion for 6 or 48 h.ResultsInfarct sizes were reduced by 68 and 60% (P&lt;0.001) in AG‐ (n=6) and UAG‐treated mice (n=5), respectively. Unlike the UAG‐treated group, mice treated with AG showed increased fractional uptake rate (Ki) and net (Km) uptake of free fatty acids (FFA), by 46% (P&lt;0.01) and 44% (P&lt;0.05), respectively, using micropositron emission tomography. Plasma FFA concentrations and glycemia, however, were not significantly different between groups.ConclusionOur results show that both AG and UAG are cardioprotective against MI/R, but exert different cardiometabolic effects, with UAG protecting against the early increased FA uptake following reperfusion of ischemic hearts. Our study suggests that UAG could be a promising therapy to reduce myocardial ischemia/reperfusion injury.Supported by the Heart and Stroke Foundation of Quebec and the Canadian Institutes of Health Research.

Adipocentric View of the Cardiometabolic Alternations Related to Abdominal Obesity

Body fat distribution patterns in humans are heterogeneous and result from regional differences in intrinsic properties of adipose cells as well as local hormonal effects. Under chronic overfeeding conditions, adipose tissue expansion in a given compartment occurs by adipocyte hypertrophy (enlargement of existing adipocytes through triglyceride synthesis), and/or adipocyte hyperplasia (generation of new adipocytes through differentiation of preadipocytes). Visceral adipocytes (e.g. omental fat cells) are efficient for hypertrophy through lipid storage and show high lipolytic responsiveness, whereas subcutaneous cells have a higher capacity for hyperplasia. Our results demonstrate that visceral adipocyte hypertrophy and high diacylglycerol acyltransferase activity are independently related to hypertriglyceridemia and triglyceride enrichment of circulating lipoproteins. Moreover, low capacity for adipogenic differentiation of preadipocytes in the subcutaneous fat compartment is a significant predictor of excess visceral adipose tissue accumulation, visceral adipocyte hypertrophy, triglyceride enrichment of lipoproteins and fasting hyperglycemia. Adipose tissue-derived cytokines and immune cells infiltrating adipose tissues also mediate the link between visceral obesity and cardiometabolic alterations increasing type 2 diabetes and cardiovascular disease risk. These inflammatory phenotypes are also observed in patients with visceral adipocyte hypertrophy when compared to those who predominantly exhibit hyperplasic adipose tissue expansion. Overall, in individuals with elevated cardiometabolic risk, adipose tissue function impairments include adipocyte hypertrophy, impaired adipogenesis, low free fatty acid uptake, reduced triglyceride synthesis, resistance to the inhibitory effect of insulin on lipolysis, immune cell infiltration and inflammatory cytokine secretion. These alterations collectively reflect reduced storage capacity of fat tissues and contribute to systemic metabolic perturbation.

Pregnancy Up‐regulate Genes Involved in Glucose and Lipids Metabolism in the Left Ventricle of Rat

Hypertrophic cardiomyopathy up‐regulates HIF‐1α and PPARγ to cooperatively to mediate important changes in cardiac metabolism that are characteristic of and contribute to common forms of heart disease. HIF‐1α activates glycolytic genes, and PPARγ facilitates the uptake of free fatty acids uptake and genes involved with glycerol‐lipid biosynthesis in response to pathologic stress. Therefore, these changes increase the rate of glycolysis and glucose‐to‐lipid ratio via glycerol‐3‐phosphate pathway, apoptosis, and contractile dysfunction. However, the expression of genes regulated by HIF‐1α and PPARγ in physiologic hypertrophy induced by pregnancy and its reversible process (postpartum) are not well defined. In the present study, we quantified HIF‐1α (HK2, PFKM, GAPDH and PK4) and PPARγ (GPAT and GPD1) target genes before (not pregnancy, NP), during late pregnancy (LP, 21 days) and after pregnancy (PP, 7 days) in the left ventricle of rats. Levels of mRNA for the glycolytic genes HK2, PFKM and GAPDH increased 1.6‐, 3.2‐ and 2‐ fold during LP and decreased to basal level after PP, respectively, while PK mRNA levels decreased during LP and returned to basal level after PP. The glycerol‐lipid biosynthesis genes GPAT and GPD1 increased 14‐ and 3‐ folds during EP and decreased to basal levels after PP, respectively. Results demonstrate that pregnancy induces the expression of glycolytic and glycerol‐lipid biosynthesis genes suggesting a shift in cardiac metabolism by activation of HIF‐1α and PPARγ.

The exocyst complex regulates free fatty acid uptake by adipocytes.

The exocyst is an octameric molecular complex that drives vesicle trafficking in adipocytes, a rate-limiting step in insulin-dependent glucose uptake. This study assessed the role of the exocyst complex in regulating free fatty acid (FFA) uptake by adipocytes. Upon differentiating into adipocytes, 3T3-L1 cells acquire the ability to incorporate extracellular FFAs in an insulin-dependent manner. A kinetic assay using fluoresceinated FFA (C12 dodecanoic acid) uptake allows the real-time monitoring of FFA internalization by adipocytes. The insulin-dependent uptake of C12 dodecanoic acid by 3T3-L1 adipocytes is mediated by Akt and phosphatidylinositol 3 (PI3)-kinase. Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes. Consistent with the roles played by Exo70 and Sec8 in FFA uptake, mCherry-tagged Exo70 and HA-tagged Sec8 partially colocalize with lipid droplets within adipocytes, suggesting their active roles in the development of lipid droplets. Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex. This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

Muscle-specific glucose and free fatty acid uptake after sprint interval and moderate-intensity training in healthy middle-aged men.

We tested the hypothesis that sprint interval training (SIT) causes larger improvements in glucose and free fatty acid uptake (FFAU) in lower and upper body muscles than moderate-intensity training (MIT). Twenty-eight healthy, untrained, middle-aged men were randomized into SIT (n = 14, 4-6 × 30 s of all-out cycling/4 min recovery) and MIT groups [n = 14, 40-60 min cycling at 60% of peak O2 uptake (V̇o2 peak)] and completed six training sessions within 2 wk. Pre- and postmeasurements included V̇o2 peak, whole body (M-value), muscle-specific insulin-stimulated glucose uptake (GU), and fasting FFAU measured with positron emission tomography in thigh [quadriceps femoris (QF) and hamstrings] and upper body (deltoids, biceps, and triceps brachii) muscles. V̇o2 peak and M-value improved significantly by 6 and 12% in SIT, and 3 and 8% in MIT, respectively,. GU increased significantly only in the QF, and there was no statistically significant difference between the training modes. GU increased in all four heads of QF in response to SIT, but only in the vasti muscles in response to MIT, whereas in rectus femoris the response was completely lacking. Training response in FFAU in QF was smaller and nonsignificant, but it also differed between the training modes in the rectus femoris. In conclusion, SIT and MIT increased insulin-stimulated GU only in the main working muscle QF and not in the upper body muscles. In addition, the biarticular rectus femoris did not respond to moderate-intensity training, reflecting most probably poor activation of it during moderate-intensity cycling.

Developmental bisphenol A (BPA) exposure leads to sex-specific modification of hepatic gene expression and epigenome at birth that may exacerbate high-fat diet-induced hepatic steatosis

Developmental bisphenol A (BPA) exposure increases adulthood hepatic steatosis with reduced mitochondrial function. To investigate the potential epigenetic mechanisms behind developmental BPA-induced hepatic steatosis, pregnant Sprague–Dawley rats were dosed with vehicle (oil) or BPA (100μg/kg/day) from gestational day 6 until postnatal day (PND) 21. After weaning, offspring were either challenged with a high-fat (HF; 45% fat) or remained on a control (C) diet until PND110. From PND60 to 90, both BPA and HF diet increased the fat/lean ratio in males only, and the combination of BPA and HF diet appeared to cause the highest ratio. On PND110, Oil-HF, BPA-C, and BPA-HF males had higher hepatic lipid accumulation than Oil-C, with microvesicular steatosis being marked in the BPA-HF group. Furthermore, on PND1, BPA increased and modified hepatic triglyceride (TG) and free fatty acid (FFA) compositions in males only. In PND1 males, BPA increased hepatic expression of FFA uptake gene Fat/Cd36, and decreased the expression of TG synthesis- and β-oxidation-related genes (Dgat, Agpat6, Cebpα, Cebpβ, Pck1, Acox1, Cpt1a, Cybb). BPA altered DNA methylation and histone marks (H3Ac, H4Ac, H3Me2K4, H3Me3K36), and decreased the binding of several transcription factors (Pol II, C/EBPβ, SREBP1) within the male Cpt1a gene, the key β-oxidation enzyme. In PND1 females, BPA only increased the expression of genes involved in FFA uptake and TG synthesis (Lpl, Fasn, and Dgat). These data suggest that developmental BPA exposure alters and reprograms hepatic β-oxidation capacity in males, potentially through the epigenetic regulation of genes, and further alters the response to a HF diet.

Multicentre double-blind randomized controlled trial of perhexiline as a metabolic modulator to augment myocardial protection in patients with left ventricular hypertrophy undergoing cardiac surgery.

Patients undergoing cardiac surgery require adequate myocardial protection. Manipulating myocardial metabolism may improve the extent of myocardial protection. Perhexiline has been shown to be an effective anti-anginal agent due to its metabolic modulation properties by inhibiting the uptake of free fatty acids into the mitochondrion, and thereby promoting a more efficient carbohydrate-driven myocardial metabolism. Metabolic modulation may augment myocardial protection, particularly in patients with left ventricular hypertrophy (LVH) known to have a deranged metabolic state and are at risk of poor postoperative outcomes. This study aimed to evaluate the role of perhexiline as an adjunct in myocardial protection in patients with LVH secondary to aortic stenosis (AS), undergoing an aortic valve replacement (AVR). In a multicentre double-blind randomized controlled trial of patients with AS undergoing AVR ± coronary artery bypass graft surgery, patients were randomized to preoperative oral therapy with either perhexiline or placebo. The primary end point was incidence of inotrope use to improve haemodynamic performance due to a low cardiac output state during the first 6 h of reperfusion, judged by a blinded end points committee. Secondary outcome measures included haemodynamic measurements, electrocardiographic and biochemical markers of new myocardial injury and clinical safety outcome measures. The trial was halted early on the advice of the Data Safety and Monitoring Board. Sixty-two patients were randomized to perhexiline and 65 to placebo. Of these, 112 (54 perhexiline and 48 placebo) patients received the intervention, remained in the trial at the time of the operation and were analysed. Of 110 patients who achieved the primary end point, 30 patients (16 perhexiline and 14 placebo) had inotropes started appropriately; there was no difference in the incidence of inotrope usage OR of 1.65 [confidence interval (CI): 0.67-4.06] P = 0.28. There was no difference in myocardial injury as evidenced by electrocardiogram odds ratio (OR) of 0.36 (CI: 0.07-1.97) P = 0.24 or postoperative troponin release. Gross secondary outcome measures were comparable between the groups. Perhexiline as a metabolic modulator to enhance standard myocardial protection does not provide an additional benefit in haemodynamic performance or attenuate myocardial injury in the hypertrophied heart secondary to AS. The role of perhexiline in cardiac surgery is limited.

Lipoprotein lipase, tissue expression and effects on genes related to fatty acid synthesis in goat mammary epithelial cells.

Lipoprotein lipase (LPL) serves as a central factor in hydrolysis of triacylglycerol and uptake of free fatty acids from the plasma. However, there are limited data concerning the action of LPL on the regulation of milk fat synthesis in goat mammary gland. In this investigation, we describe the cloning and sequencing of the LPL gene from Xinong Saanen dairy goat mammary gland, along with a study of its phylogenetic relationships. Sequence analysis showed that goat LPL shares similarities with other species including sheep, bovine, human and mouse. LPL mRNA expression in various tissues determined by RT-qPCR revealed the highest expression in white adipose tissue, with lower expression in heart, lung, spleen, rumen, small intestine, mammary gland, and kidney. Expression was almost undetectable in liver and muscle. The expression profiles of LPL gene in mammary gland at early, peak, mid, late lactation, and the dry period were also measured. Compared with the dry period, LPL mRNA expression was markedly greater at early lactation. However, compared with early lactation, the expression was lower at peak lactation and mid lactation. Despite those differences, LPL mRNA expression was still greater at peak, mid, and late lactation compared with the dry period. Using goat mammary epithelial cells (GMEC), the in vitro knockdown of LPL via shRNA or with Orlistat resulted in a similar degree of down-regulation of LPL (respectively). Furthermore, knockdown of LPL was associated with reduced mRNA expression of SREBF1, FASN, LIPE and PPARG but greater expression of FFAR3. There was no effect on ACACA expression. Orlistat decreased expression of LIPE, FASN, ACACA, and PPARG, and increased FFAR3 and SREBF1 expression. The pattern of LPL expression was similar to the changes in milk fat percentage in lactating goats. Taken together, results suggest that LPL may play a crucial role in fatty acid synthesis.

Bone Marrow Adipocyte-Derived Free Fatty Acids Induce Gene Signature Linking Transcription with Metabolic Changes That Contribute to Survival of Acute Monocytic Leukemia Cells

Adipocytes are the prevalent stromal cell type in adult bone marrows (BM). With increasing age, BM stroma-resident mesenchymal stem cells (MSCs), increase their capacity to differentiate into adipocytes, which leads to the progressive accumulation of fat in the BM space. It is conceivable that the increased BM adipocyte content promotes leukemogenesis and negatively affects responsiveness to chemotherapy. We previously reported that free fatty acids (FFAs) promote the metabolic shift from pyruvate oxidation to fatty acid oxidation (FAO), which causes uncoupling of mitochondrial oxidative phosphorylation and promotes leukemia cell survival (Samudio, J Clin Invest. 2010). We further demonstrated the prominent antiapoptotic effects of BM-derived adipocytes co-cultured with cells from acute monocytic leukemia (AMoL), a poor-prognosis subtype of AML (Tabe ASH. 2013). Proteomic analysis with isobaric tags for relative and absolute quantification (iTRAQ) showed upregulation of protein folding pathways which increases the expression of antiapoptotic chaperone proteins HSP70 and HSP90, of integrin-mediated cell adhesion and migration pathways and downregulation of oxidative phosphorylation along with repression of cytochrome c.Metacore gene ontology (GO) analysis identified NF-kB, c-Jun, SP1, AP-1, and HMG as the potent relevant transcription factors that closely interact with and activate chaperone proteins, chromatin, and gene transcription.In this study, we characterized a gene signature linking transcription with metabolic changes that contribute to AMoL cell survival under conditions mimicking aging BM with prevalent adipocytes. We confirmed the antiapoptotic role of FFAs produced by the primary BM MSC-derived adipocytes via pharmacologic inhibition of FAO by etomoxir (EX), which inhibits fatty acid entry into the mitochondria. EX (50mM) treatment reversed the prosurvival effects of adipocytes on serum-starved U937 monoblast cells (% Annexin V, -/+ EX: mono-culture, 30.1±9.0 / 31.5±4.6; co-culture with adipocytes, 8.9±2.1 / 29.6±9.2; P=0.02).To assess the molecular links between metabolic pathways and gene expression triggered by BM adipocytes, we performed RNA-seq transcriptome analysis with a next generation sequencer system HiSeq1500 (Illumina) using TopHat software for alignment and Cufflinks software for identifying differential gene expression. RNA-Seq detected upregulation of 21 genes in U937 cells after co-culture with BM-derived adipocytes (false discovery rate, <0.05). Specifically, 10 of these upregulated genes were significantly decreased by EX treatment, including transcription factor–activating PPARg2 promoter KLF9, co-chaperone immunophilin protein FKBP5, chemokine CXCL12 receptor CXCR4, receptor tyrosine kinase FLT3, PI3K negative regulator PIK3IP1, and immunosuppressive transcriptional regulator TSC22D3. GO pathway analysis further revealed that co-culture with adipocytes induced upregulation of antioxidant thioredoxin peroxidase activity, which was reversed by EX. Together with the iTRAQ GO results, the antioxidative chaperone proteins might play critical roles in regulation of FAO with repression of oxidative phosphorylation in AMoL cells in adipocytes abundant BM.DNA array (GeneSQUARE) analysis and quantitative RT-PCR detected upregulation of fatty acid binding protein 4 (FABP4), scavenger receptor CD36, nuclear receptor PPARG, and antiapoptotic Bcl-2 in U937 cells co-cultured with adipocytes. It is known that FFAs, the ligand of nuclear receptor PPARγ, activate PPARγ and promote FFA uptake through transcriptional induction of CD36 and FABP4 in monocytic cells. EX treatment, which blocks the entry of fatty acids into the mitochondria, induced prominent elevation of FABP4 in U937 cells co-cultured with adipocytes. These results indicate that the FABP4-mediated internalization and ligation of fatty acids to PPARγ facilitates transcriptional activation.From the transcriptome analysis and the mitochondrial uncoupling metabolic changes, we conclude that the survival of AMoL cells depends on the cooperative interactions between lipid metabolism and transcriptional activation of factors associated with chaperones, chemokines, and integrins. Strategies targeting FAO warrant further exploration in patients with monocytic leukemia, which is highly dependent on altered lipid metabolism. DisclosuresNo relevant conflicts of interest to declare.

Concepts and Treatment Approaches in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) affects up to 30% of adults and is the most common liver disease in Western nations. NAFLD is associated with central adiposity, insulin resistance, type 2 diabetes mellitus, hyperlipidemia, and cardiovascular disease. It encompasses the entire spectrum of fatty liver diseases from simple steatosis to nonalcoholic steatohepatitis (NASH) with lobular/portal inflammation, hepatocellular necrosis, and fibrosis. Of those who develop NASH, 15–25% will progress to end stage liver disease and hepatocellular carcinoma over 10–20 years. Its pathogenesis is complex, and involves a state of lipid accumulation due to increased uptake of free fatty acids into the liver, impaired fatty acid beta oxidation, and increased incidence of de novo lipogenesis. Plasma aminotransferases and liver ultrasound are helpful in the diagnosis of NAFLD/NASH, but a liver biopsy is often required for definitive diagnosis. Many new plasma biomarkers and imaging techniques are now available that should improve the ability to diagnose NAFLD noninvasively Due to its complexity and extrahepatic complications, treatment of NAFLD requires a multidisciplinary approach with excellent preventative care, management, and treatment. This review will evaluate our current understanding of NAFLD, with a focus on existing therapeutic approaches and potential pharmacological developments.

Free Fatty Acid Uptake in Humans With CD36 Deficiency

Animal models have demonstrated that CD36 facilitates cell membrane free fatty acid (FFA) transport, but its role in human metabolism is not well understood. We measured heart, liver, adipose (three depots), and muscle (truncal postural and thigh locomotive) FFA uptake using [11C]palmitate positron emission tomography (PET) scans in a family of five carrying the Pro90Ser CD36 mutation (2 homozygotes had no CD36) and matched control volunteers. PET scans were done under conditions of suppressed and slightly increased palmitate concentrations. During suppressed palmitate conditions, muscle and adipose palmitate uptake were markedly reduced in homozygotes but not heterozygotes for the Pro90Ser CD36 mutation, whereas when palmitate concentration was slightly increased, uptake in muscle and adipose did not differ between control subjects and homozygous family members. Hepatic FFA uptake was similar in all participants regardless of palmitate concentrations, whereas myocardial FFA uptake was diminished in the Pro90Ser homozygotes during both suppressed and increased palmitate conditions. We conclude that CD36 1) facilitates FFA transport into muscle and adipose tissue in humans when extracellular concentrations are reduced but not when they are modestly elevated, 2) is not rate limiting for hepatic FFA uptake, and 3) is needed for normal cardiac FFA uptake over a range of FFA concentrations from low to slightly elevated.