Low HDL-cholesterol levels predict hepatocellular carcinoma development in individuals with liver fibrosis

Background & Aims

Dysmetabolic conditions could drive liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD), increasing susceptibility to hepatocellular carcinoma (HCC). We therefore aimed to identify novel predictive biomarkers of HCC in patients with and without liver fibrosis.

Methods

A total of 1,234 patients with putative metabolic conditions and NAFLD were consecutively assessed in our outpatient clinic. Clinical and biochemical data were recorded, and then liver ultrasonography was performed annually for 5 years to detect HCC onset. For the analysis, the population was first divided according to HCC diagnosis; then a further subdivision of those who did not develop HCC was performed based on the presence or absence of liver fibrosis at time 0.

Results

Sixteen HCC cases were recorded in 5 years. None of our patients had been diagnosed with cirrhosis before HCC was detected. Compared to patients who did not develop HCC, those who did had higher liver transaminases and fibrosis scores at time 0 (p <0.001). In addition, they presented with increased glycated haemoglobin levels and lower 25-OH vitamin D levels (p <0.05). Intriguingly, patients with higher liver fibrosis scores who subsequently developed HCC had lower HDL-cholesterol (HDL-c) levels at time 0 (p <0.001). Furthermore, in the 484 patients presenting with lower HDL-c at baseline, we found that waist circumference, and then vitamin D and glycated haemoglobin levels, were significantly different in those who developed HCC, regardless of liver fibrosis (p <0.05).

Conclusions

This study identifies HDL-c as a bona fide novel marker to predict HCC in patients with NAFLD. Increased waist circumference and deranged metabolic pathways represent additional predisposing factors among patients with low HDL-c, highlighting the importance of studying cholesterol metabolism and integrating clinical approaches with dietary regimens and a healthy lifestyle to prevent HCC.

Impact and implications

Visceral adiposity and its associated conditions, such as chronic inflammation and insulin resistance, may play a pivotal role in hepatocellular carcinoma development in patients with non-alcoholic fatty liver disease. We provide new insights on the underlying mechanisms of its pathogenesis, shedding light on the involvement of low levels of "good" HDL-cholesterol. We recommend integrating dietary regimens and advice on healthy lifestyles into the clinical management of non-alcoholic fatty liver disease, with the goal of reducing the incidence of hepatocellular carcinoma.

Nicotinamide Mononucleotide Alleviates Cardiomyopathy Phenotypes Caused by Short-Chain Enoyl-Coa Hydratase 1 Deficiency

•

ECHS1 hydrates medium- and short-chain enoyl CoAs and catalyzes the oxidation of fatty acids and branched-chain amino acids.

•

The mechanism driving ECHS1 deficiency–associated cardiomyopathy was investigated using conventional biochemistry and molecular biology methods, including immunoprecipitation and polymerase chain reaction.

•

Echs1 heterogeneous knockout mice displayed cardiac dysfunction as evaluated by echocardiography.

•

ECHS1 deficiency causes cardiomyopathy by enhancing p300-mediated H3K9ac.

•

ECHS1 deficiency–induced cardiomyopathy can be prevented using an intervention approach targeting H3K9ac.

Short-chain enoyl-CoA hydratase 1 (ECHS1) deficiency plays a role in cardiomyopathy. Whether ECHS1 deficiency causes or is only associated with cardiomyopathy remains unclear. By using Echs1 heterogeneous knockout (Echs1^+/-) mice, we found that ECHS1 deficiency caused cardiac dysfunction, as evidenced by diffuse myocardial fibrosis and upregulated fibrosis-related genes. Mechanistically, ECHS1 interacts with the p300 nuclear localization sequence, preventing its nuclear translocation in fibroblasts. ECHS1 deficiency promotes p300 nuclear translocation, leading to increased H3K9 acetylation, a known risk factor for cardiomyopathy. Nicotinamide mononucleotide–mediated acetylation targeting suppressed ECHS1 deficiency–induced cardiomyopathy phenotypes in Echs1^+/- mice. Thus, enhancing p300-mediated H3K9ac is a potential interventional approach for preventing ECHS1 deficiency–induced cardiomyopathy.

The small molecule SERCA activator CDN1163 increases energy metabolism in human skeletal muscle cells

Background and objective

A number of studies have highlighted muscle-specific mechanisms of thermogenesis involving futile cycling of Ca²⁺ driven by sarco (endo)plasmic reticulum Ca²⁺-ATPase (SERCA) and generating heat from ATP hydrolysis to be a promising strategy to counteract obesity and metabolic dysfunction. However, to the best of our knowledge, no experimental studies concerning the metabolic effects of pharmacologically targeting SERCA in human skeletal muscle cells have been reported. Thus, in the present study, we aimed to explore the effects of SERCA-activating compound, CDN1163, on energy metabolism in differentiated human skeletal muscle cells (myotubes).

Methods

In this study, we used primary myotube cultures derived from muscle biopsies of the musculus vastus lateralis and musculi interspinales from lean, healthy male donors. Energy metabolism in myotubes was studied using radioactive substrates. Oxygen consumption rate was assessed with the Seahorse XF24 bioanalyzer, whereas metabolic genes and protein expressions were determined by qPCR and immunoblotting, respectively.

Results

Both acute (4 ​h) and chronic (5 days) treatment of myotubes with CDN1163 showed increased uptake and oxidation of glucose, as well as complete fatty acid oxidation in the presence of carbonyl cyanide 4-(trifluromethoxy)phenylhydrazone (FCCP). These effects were supported by measurement of oxygen consumption rate, in which the oxidative spare capacity and maximal respiration were enhanced after CDN1163-treatment. In addition, chronic treatment with CDN1163 improved cellular uptake of oleic acid (OA) and fatty acid β-oxidation. The increased OA metabolism was accompanied by enhanced mRNA-expression of carnitine palmitoyl transferase (CPT) 1B, pyruvate dehydrogenase kinase (PDK) 4, as well as increased AMP-activated protein kinase (AMPK)^Thr172 phosphorylation. Moreover, following chronic CDN1163 treatment, the expression levels of stearoyl-CoA desaturase (SCD) 1 was decreased together with de novo lipogenesis from acetic acid and formation of diacylglycerol (DAG) from OA.

Conclusion

Altogether, these results suggest that SERCA activation by CDN1163 enhances energy metabolism in human myotubes, which might be favourable in relation to disorders that are related to metabolic dysfunction such as obesity and type 2 diabetes mellitus.

•

CDN1163 induced an increase in glucose and fatty acid metabolism in primary human myotubes.

•

Myotubes treated with CDN1163 showed lower intramyocellular lipid accumulation and higher rate of β-oxidation.

•

AMPK activity was upregulated in CDN1163-treated myotubes.

The fatty acid site is coupled to functional motifs in the SARS-CoV-2 spike protein and modulates spike allosteric behaviour

The SARS-CoV-2 spike protein is the first contact point between the SARS-CoV-2 virus and host cells and mediates membrane fusion. Recently, a fatty acid binding site was identified in the spike (Toelzer et al. Science 2020). The presence of linoleic acid at this site modulates binding of the spike to the human ACE2 receptor, stabilizing a locked conformation of the protein. Here, dynamical-nonequilibrium molecular dynamics simulations reveal that this fatty acid site is coupled to functionally relevant regions of the spike, some of them far from the fatty acid binding pocket. Removal of a ligand from the fatty acid binding site significantly affects the dynamics of distant, functionally important regions of the spike, including the receptor-binding motif, furin cleavage site and fusion-peptide-adjacent regions. Simulations of the D614G mutant show differences in behaviour between these clinical variants of the spike: the D614G mutant shows a significantly different conformational response for some structural motifs relevant for binding and fusion. The simulations identify structural networks through which changes at the fatty acid binding site are transmitted within the protein. These communication networks significantly involve positions that are prone to mutation, indicating that observed genetic variation in the spike may alter its response to linoleate binding and associated allosteric communication.

Maternal malnutrition and anaemia in India: dysregulations leading to the 'thin-fat' phenotype in newborns

Maternal and child malnutrition and anaemia remain the leading factors for health loss in India. Low birth weight (LBW) offspring of women suffering from chronic malnutrition and anaemia often exhibit insulin resistance and infantile stunting and wasting, together with increased risk of developing cardiometabolic disorders in adulthood. The resulting self-perpetuating and highly multifactorial disease burden cannot be remedied through uniform dietary recommendations alone. To inform approaches likely to alleviate this disease burden, we implemented a systems-analytical approach that had already proven its efficacy in multiple published studies. We utilised previously published qualitative and quantitative analytical results of rural and urban field studies addressing maternal and infantile metabolic and nutritional parameters to precisely define the range of pathological phenotypes encountered and their individual biological characteristics. These characteristics were then integrated, via extensive literature searches, into metabolic and physiological mechanisms to identify the maternal and foetal metabolic dysregulations most likely to underpin the ‘thin-fat’ phenotype in LBW infants and its associated pathological consequences. Our analyses reveal hitherto poorly understood maternal nutrition-dependent mechanisms most likely to promote and sustain the self-perpetuating high disease burden, especially in the Indian population. This work suggests that it most probably is the metabolic consequence of ‘ill-nutrition’ – the recent and rapid dietary shifts to high salt, high saturated fats and high sugar but low micronutrient diets – over an adaptation to ‘thrifty metabolism’ which must be addressed in interventions aiming to significantly alleviate the leading risk factors for health deterioration in India.

Peroxisomal Fatty Acid Oxidation and Glycolysis Are Triggered in Mouse Models of Lesional Atopic Dermatitis

Alterations of the lipid profile of the stratum corneum have an important role in the pathogenesis of atopic dermatitis (AD) because they contribute to epidermal barrier impairment. However, they have not previously been envisioned as a cellular response to altered metabolic requirements in AD epidermis. In this study, we report that the lipid composition in the epidermis of flaky tail, that is, ft/ft mice mimics that of human lesional AD (ADL) epidermis, both showing a shift toward shorter lipid species. The amounts of C24 and C26 free fatty acids and C24 and C26 ceramides-oxidized exclusively in peroxisomes-were reduced in the epidermis of ft/ft mice despite increased lipid synthesis, similar to that seen in human ADL edpidermis. Increased ACOX1 protein and activity in granular keratinocytes of ft/ft epidermis, altered lipid profile in human epidermal equivalents overexpressing ACOX1, and increased ACOX1 immunostaining in skin biopsies from patients with ADL suggest that peroxisomal β-oxidation significantly contributes to lipid signature in ADL epidermis. Moreover, we show that increased anaerobic glycolysis in ft/ft mouse epidermis is essential for keratinocyte proliferation and adenosine triphosphate synthesis but does not contribute to local inflammation. Thus, this work evidenced a metabolic shift toward enhanced peroxisomal β-oxidation and anaerobic glycolysis in ADL epidermis.

An update on oral drug delivery via intestinal lymphatic transport

Orally administered drug entities have to survive the harsh gastrointestinal environment, penetrate the enteric epithelia and circumvent hepatic metabolism before reaching the systemic circulation. Whereas the gastrointestinal stability can be well maintained by taking proper measures, hepatic metabolism presents as a formidable barrier to drugs suffering from first-pass metabolism. The pharmaceutical academia and industries are seeking alternative pathways for drug transport to circumvent problems associated with the portal pathway. Intestinal lymphatic transport is emerging as a promising pathway to this end. In this review, we intend to provide an updated overview on the rationale, strategies, factors and applications involved in intestinal lymphatic transport. There are mainly two pathways for peroral lymphatic transport-the chylomicron and the microfold cell pathways. The underlying mechanisms are being unraveled gradually and nowadays witness increasing research input and applications.

A human liver chimeric mouse model for non-alcoholic fatty liver disease

Background & Aims

The accumulation of neutral lipids within hepatocytes underlies non-alcoholic fatty liver disease (NAFLD), which affects a quarter of the world's population and is associated with hepatitis, cirrhosis, and hepatocellular carcinoma. Despite insights gained from both human and animal studies, our understanding of NAFLD pathogenesis remains limited. To better study the molecular changes driving the condition we aimed to generate a humanised NAFLD mouse model.

Methods

We generated TIRF (transgene-free Il2rg ^-/-/Rag2 ^-/-/Fah ^-/-) mice, populated their livers with human hepatocytes, and fed them a Western-type diet for 12 weeks.

Results

Within the same chimeric liver, human hepatocytes developed pronounced steatosis whereas murine hepatocytes remained normal. Unbiased metabolomics and lipidomics revealed signatures of clinical NAFLD. Transcriptomic analyses showed that molecular responses diverged sharply between murine and human hepatocytes, demonstrating stark species differences in liver function. Regulatory network analysis indicated close agreement between our model and clinical NAFLD with respect to transcriptional control of cholesterol biosynthesis.

Conclusions

These NAFLD xenograft mice reveal an unexpected degree of evolutionary divergence in food metabolism and offer a physiologically relevant, experimentally tractable model for studying the pathogenic changes invoked by steatosis.

Lay summary

Fatty liver disease is an emerging health problem, and as there are no good experimental animal models, our understanding of the condition is poor. We here describe a novel humanised mouse system and compare it with clinical data. The results reveal that the human cells in the mouse liver develop fatty liver disease upon a Western-style fatty diet, whereas the mouse cells appear normal. The molecular signature (expression profiles) of the human cells are distinct from the mouse cells and metabolic analysis of the humanised livers mimic the ones observed in humans with fatty liver. This novel humanised mouse system can be used to study human fatty liver disease.

Engineering precursor pools for increasing production of odd-chain fatty acids in Yarrowia lipolytica

Microbial production of lipids is one of the promising alternatives to fossil resources with increasing environmental and energy concern. Odd-chain fatty acids (OCFA), a type of unusual lipids, are recently gaining a lot of interest as target compounds in microbial production due to their diverse applications in the medical, pharmaceutical, and chemical industries. In this study, we aimed to enhance the pool of precursors with three-carbon chain (propionyl-CoA) and five-carbon chain (β-ketovaleryl-CoA) for the production of OCFAs in Yarrowia lipolytica. We evaluated different propionate-activating enzymes and the overexpression of propionyl-CoA transferase gene from Ralstonia eutropha increased the accumulation of OCFAs by 3.8 times over control strain, indicating propionate activation is the limiting step of OCFAs synthesis. It was shown that acetate supplement was necessary to restore growth and to produce a higher OCFA contents in total lipids, suggesting the balance of the precursors between acetyl-CoA and propionyl-CoA is crucial for OCFA accumulation. To improve β-ketovaleryl-CoA pools for further increase of OCFA production, we co-expressed the bktB encoding β-ketothiolase in the producing strain, and the OCFA production was increased by 33% compared to control. Combining strain engineering and the optimization of the C/N ratio promoted the OCFA production up to 1.87 ​g/L representing 62% of total lipids, the highest recombinant OCFAs titer reported in yeast, up to date. This study provides a strong basis for the microbial production of OCFAs and its derivatives having high potentials in a wide range of applications.

VEGF-B antibody and interleukin-22 fusion protein ameliorates diabetic nephropathy through inhibiting lipid accumulation and inflammatory responses

Diabetic nephropathy (DN) is considered the primary causes of end-stage renal disease (ESRD) and is related to abnormal glycolipid metabolism, hemodynamic abnormalities, oxidative stress and chronic inflammation. Antagonism of vascular endothelial growth factor B (VEGF-B) could efficiently ameliorate DN by reducing renal lipotoxicity. However, this pharmacological strategy is far from satisfactory, as it ignores numerous pathogenic factors, including anomalous reactive oxygen species (ROS) generation and inflammatory responses. We found that the upregulation of VEGF-B and downregulation of interleukin-22 (IL-22) among DN patients were significantly associated with the progression of DN. Thus, we hypothesized that a combination of a VEGF-B antibody and IL-22 could protect against DN not only by regulating glycolipid metabolism but also by reducing the accumulation of inflammation and ROS. To meet these challenges, a novel anti-VEGFB/IL22 fusion protein was developed, and its therapeutic effects on DN were further studied. We found that the anti-VEGFB/IL22 fusion protein reduced renal lipid accumulation by inhibiting the expression of fatty acid transport proteins and ameliorated inflammatory responses via the inhibition of renal oxidative stress and mitochondrial dysfunction. Moreover, the fusion protein could also improve diabetic kidney disease by increasing insulin sensitivity. Collectively, our findings indicate that the bifunctional VEGF-B antibody and IL-22 fusion protein could improve the progression of DN, which highlighted a novel therapeutic approach to DN.

Hepatic miR-192-3p reactivation alleviates steatosis by targeting glucocorticoid receptor

Background & Aims

The paradox of hepatic insulin resistance describes the inability for liver to respond to bioenergetics hormones in suppressing gluconeogenesis whilst maintaining lipid synthesis. Here, we report the deficiency of miR-192-3p in the livers of mice with diabetes and its role in alleviating hepatic steatosis.

Methods

As conventional pre-microRNA (miRNA) stem-loop overexpression only boosts guiding strand (i.e. miR-192-5p) expression, we adopted an artificial AAV(DJ)-directed, RNA Pol III promoter-driven miRNA hairpin construct for star-strand-specific overexpression in the liver. Liver steatosis and insulin resistance markers were evaluated in primary hepatocytes, mice with diabetes, and mice with excessive carbohydrate consumption.

Results

Functional loss of miR-192-3p in liver exacerbated hepatic micro-vesicular steatosis and insulin resistance in either mice with diabetes or wild-type mice with excessive fructose consumption. Liver-specific overexpression of miR-192-3p effectively halted hepatic steatosis and ameliorated insulin resistance in these mice models. Likewise, hepatocytes overexpressing miR-192-3p exhibited improved lipid accumulation, accompanied with decreases in lipogenesis and lipid-accumulation-related transcripts. Mechanistically, glucocorticoid receptor (GCR, also known as nuclear receptor subfamily 3, group C, member 1 [NR3C1]) was demonstrated to be negatively regulated by miR-192-3p. The effect of miR-192-3p on mitigating micro-vesicular steatosis was ablated by the reactivation of NR3C1.

Conclusions

The star strand miR-192-3p was an undermined glycerolipid regulator involved in controlling fat accumulation and insulin sensitivity in liver through blockade of hepatic GCR signalling; this miRNA may serve as a potential therapeutic option for the common co-mobility of diabetic mellitus and fatty liver disease.

Lay summary

The potential regulatory activity of star strand microRNA (miRNA) species has been substantially underestimated. In this study, we investigate the role and mechanism of an overlooked star strand miRNA (miR-192-3p) in regulating hepatic steatosis and insulin signalling in the livers of mice with diabetes and mice under excessive carbohydrate consumption.

•

Liver-specific knockdown of miR-192-3p recapitulated functional loss of the miRNA as in mice with diabetes.

•

This knockdown was characterised by pronounced hepatic micro-vesicular steatosis coupled to insulin resistance.

•

In vivo overexpression of miR-192-3p alleviated hepatic steatosis in mice with diabetes and wild-type mice with excessive fructose consumption.

•

Glucocorticoid receptor (also known as NR3C1) was discovered as the immediate target of miR-192-3p in regulating hepatic lipid turnover and storage.

Whole-exome mutational landscape of metastasis in patient-derived hepatocellular carcinoma cells

In order to explore the genomic basis for liver cancer metastasis, whole-exome sequencing (WES) was performed on patient-derived hepatocellular carcinoma (HCC) cell lines with differential metastatic potentials and analyzed their clonal evolution relationships. An evolutionary tree based on genomic single nucleotide polymorphism (SNP) was constructed in MegaX software. The WES data showed that the average percentage of heterogeneous mutations in each HCC cell lines was 16.55% (range, 15.38%–18.17%). C: G > T: A and T: A > C: G somatic transitions were the two most frequent substitutions. In these metastatic HCC cell lines, non-silent gene mutations were found in 21.88% of known driver genes and 10 classical signaling pathways. The protein interaction network was constructed by STRING, and hub genes were found in the shared trunk mutation genes and the heterogeneous branch mutations respectively. In cBioPortal database, some of the selected hub genes were found to be associated with poor overall survival (OS) of HCC patients. Among the mutated HCC driver genes, a novel KEAP1 mutation with a homozygous frameshift truncation at the c-terminal Nrf2 binding region was detected and verified in MHCC97-H and HCC97LM3 cells. In conclusion, WES data demonstrate that HCC cell lines from tumor biopsy specimens of the same patient have obtained different metastatic potentials through repeated selection in rodents in vivo, and they do indeed have a genetic relationship at the genomic level.

Increasing the proportion of plasma MUFA, as a result of dietary intervention, is associated with a modest improvement in insulin sensitivity

The effect of modifying dietary fatty acid (FA) composition on insulin sensitivity remains unclear. We aimed to investigate whether changes in plasma phospholipid (PL) FA composition, as a result of dietary intervention, correspond with changes in insulin sensitivity. The RISCK study was a 6-month randomised controlled dietary intervention study, which assessed the effect of modifying dietary fat and the glycaemic index (GI) of carbohydrates on insulin sensitivity. Total NEFA levels, fasting plasma PL FA profiles and an insulin sensitivity index (Si), derived from intravenous glucose tolerance minimal-model analysis, were available from 533 participants, all at elevated risk of type 2 diabetes. Bivariate correlations between changes in saturated PL FA (SFA), MUFA (as a percentage of total plasma NEFA) and changes in Si were assessed according to treatment group. Age, sex, ethnicity, percentage change in body mass and change in dietary GI were controlled for. Increasing total NEFA concentration was associated with worsening Si (r -0·152; P = 0·001). In the high-MUFA/low-GI diet group, change in PL-MUFA was positively and independently associated with change in Si (r 0·297; P = 0·002). Among MUFA, change in oleic acid (18 : 1) was most strongly correlated with change in Si (r 0·266; P = 0·005), as was change in minor FA 24 : 1 (r 0·244; P = 0·011) and 17 : 1 (r 0·196; P = 0·042). In the high-SFA/high-GI group, change in SFA concentration was not significantly associated with change in Si. In conclusion, increases in the proportion of plasma PL-MUFA following a high-MUFA dietary intervention were associated with improvements in insulin sensitivity.

Optimization of enzymatic hydrolysis of cellulosic fraction obtained from stranded driftwood feedstocks for lipid production by Solicoccozyma terricola

•

Stranded driftwood feedstocks (SD) were steam exploded and hydrolyzed.

•

The enzymatic hydrolysis was optimized using a multivariate approach (RSM).

•

The conversion of carbohydrates into lipids by S. terricola was high (Y_L = 25.26%).

•

The fatty acid profile achieved was similar to that reported for palm oil.

•

SD feedstocks resulted a cheap C-source for biofuels and biochemicals production.

Stranded driftwood feedstocks may represent, after pretreatment with steam explosion and enzymatic hydrolysis, a cheap C-source for producing biochemicals and biofuels using oleaginous yeasts. The hydrolysis was optimized using a response surface methodology (RSM). The solid loading (SL) and the dosage of enzyme cocktail (ED) were variated following a central composite design (CCD) aimed at optimizing the conversion of carbohydrates into lipids (Y_L) by the yeast Solicoccozyma terricola DBVPG 5870.

A second-order polynomial equation was computed for describing the effect of ED and SL on Y_L.

The best combination (ED = 3.10%; SL = 22.07%) for releasing the optimal concentration of carbohydrates which gave the highest predicted Y_L (27.32%) was then validated by a new hydrolysis. The resulting value of Y_L (25.26%) was close to the theoretical maximum value.

Interestingly, fatty acid profile achieved under the optimized conditions was similar to that reported for palm oil.

Phospholipase D antagonist 1-butanol inhibited the mobilization of triacylglycerol during seed germination in Arabidopsis

Storage oil breakdown plays an important role in the life cycle of many plants by providing the carbon skeletons that support seedling growth immediately following germination. 1-Butanol, a specific inhibitor of phospholipase D (PLD)-dependent production of the signalling molecule phosphatidic acid (PA), inhibited Arabidopsis seed germination. N-Acylethanolamines (NAEs), which have been shown to inhibits PLDα1 activity, have no effect on seed germination. However, mobilization profile of triacylglycerols (TAG) that induced by each compound has not been reported. To gain deeper insights into the mode of mobilization of TAG during NAE 12:0 or 1-butanol treatment, we conducted a detailed comparative analysis of the effect of NAE 12:0, DMSO, 1-butanol and tert-butanol on Arabidopsis seed germination and fatty acid composition, tert-butanol and DMSO served as the corresponding controls treatment respectively. Our data show that 1-butanol, but not the inactive tert-butanol isomer, inhibited Arabidopsis seed germination, which is accompanied by a with retardation of the mobilization of triacylglycerols (TAG). In contrast, NAE 12:0 did not affect mobilization of TAG, nor did it significantly delay seed germination as monitored by radicle and cotyledon emergence. 1-Butanol induced RNA degradation in seeds and seedlings. We speculate that the large-scale degradation of RNA under the induction of 1-butanol may lead to abnormal gene expression in genes necessary for seed germination, including the genes needed for the mobilization of oil bodies, and thus cause a delay of seed germination. To the best of our knowledge, we report for the first time that 1-butanol delays the mobilization of TAG.

Fatty Acids Prevent Hypoxia-Inducible Factor-1α Signaling Through Decreased Succinate in Diabetes

•

HIF-1α is activated following myocardial infarction, and is a critical transcription factor promoting survival in hypoxia.

•

Type 2 diabetes blunts HIF-1α activation in ischemia and downstream adaptation to hypoxia.

•

This effect is mediated by increased long-chain fatty acids, which prevent HIF-1α activation in hypoxia.

•

Succinate promotes HIF-1α activation by inhibiting the regulatory HIF hydroxylases. Fatty acids decrease succinate concentrations in hypoxia, by blocking increased glycolysis and malate-aspartate shuttle activity.

•

Pharmacologically activating HIF-1α or increasing succinate concentrations restores the hypoxic response and improves functional recovery post-ischemia in diabetes.

Hypoxia-inducible factor (HIF)-1α is essential following a myocardial infarction (MI), and diabetic patients have poorer prognosis post-MI. Could HIF-1α activation be abnormal in the diabetic heart, and could metabolism be causing this? Diabetic hearts had decreased HIF-1α protein following ischemia, and insulin-resistant cardiomyocytes had decreased HIF-1α-mediated signaling and adaptation to hypoxia. This was due to elevated fatty acid (FA) metabolism preventing HIF-1α protein stabilization. FAs exerted their effect by decreasing succinate concentrations, a HIF-1α activator that inhibits the regulatory HIF hydroxylase enzymes. In vivo and in vitro pharmacological HIF hydroxylase inhibition restored HIF-1α accumulation and improved post-ischemic functional recovery in diabetes.

Losing Reproduction: Effect of High Temperature on Female Biochemical Composition and Egg Quality in a Freshwater Crustacean with Direct Development, the Red Cherry Shrimp, Neocaridina davidi (Decapoda, Atyidae)

Maternal provisioning is particularly important in invertebrates with abbreviated development because large energy reserves must be provided for the developing embryo. In this context, the objective of the present study was to analyze in an aquatic invertebrate with direct development the effect of temperature on female biochemical composition and reserve allocation to maturing ovaries, which determine egg quality. A decapod crustacean, the freshwater shrimp Neocaridina davidi, was used as experimental model. Newly hatched juveniles were exposed to 28 °C or 33 °C. Females showed mature ovaries and spawned at 28 °C (control ovigerous females), but no ovigerous female was found at 33 °C. After a 200-day period, half of the females at 33 °C were transferred to 28 °C, where they rapidly showed mature ovaries and spawned (transferred ovigerous females). Ovigerous females and females that did not spawn at 28 °C (control non-ovigerous females) and at 33 °C (high-temperature non-ovigerous females) were sacrificed to determine their biochemical composition. The number, volume, weight, and biochemical composition of the eggs from transferred and control ovigerous females were also analyzed as indicators of their quality. Female biochemical composition was not influenced by temperature, because control and high-temperature non-ovigerous females had similar lipid, protein, and glycogen contents. However, ovarian maturation and spawning were inhibited at 33 °C, which indicates a negative effect of this temperature on nutrient transfer to the oocytes. This effect was rapidly reversed after females were moved to 28 °C; the eggs from control and transferred ovigerous females were of similar quality, except for a lower protein content in the latter. The present results provide valuable information on reserve allocation to reproduction under thermal stress.

Identification of the Consistently Altered Metabolic Targets in Human Hepatocellular Carcinoma

BACKGROUND & AIMS

Cancer cells rely on metabolic alterations to enhance proliferation and survival. Metabolic gene alterations that repeatedly occur in liver cancer are largely unknown. We aimed to identify metabolic genes that are consistently deregulated, and are of potential clinical significance in human hepatocellular carcinoma (HCC).

METHODS

We studied the expression of 2,761 metabolic genes in 8 microarray datasets comprising 521 human HCC tissues. Genes exclusively up-regulated or down-regulated in 6 or more datasets were defined as consistently deregulated. The consistent genes that correlated with tumor progression markers (ECM2 and MMP9) (Pearson correlation P < .05) were used for Kaplan-Meier overall survival analysis in a patient cohort. We further compared proteomic expression of metabolic genes in 19 tumors vs adjacent normal liver tissues.

RESULTS

We identified 634 consistent metabolic genes, ∼60% of which are not yet described in HCC. The down-regulated genes (n = 350) are mostly involved in physiologic hepatocyte metabolic functions (eg, xenobiotic, fatty acid, and amino acid metabolism). In contrast, among consistently up-regulated metabolic genes (n = 284) are those involved in glycolysis, pentose phosphate pathway, nucleotide biosynthesis, tricarboxylic acid cycle, oxidative phosphorylation, proton transport, membrane lipid, and glycan metabolism. Several metabolic genes (n = 434) correlated with progression markers, and of these, 201 predicted overall survival outcome in the patient cohort analyzed. Over 90% of the metabolic targets significantly altered at the protein level were similarly up- or down-regulated as in genomic profile.

CONCLUSIONS

We provide the first exposition of the consistently altered metabolic genes in HCC and show that these genes are potentially relevant targets for onward studies in preclinical and clinical contexts.

Dataset of the human homologues and orthologues of lipid-metabolic genes identified as DAF-16 targets their roles in lipid and energy metabolism

The data presented in this article are related to the review article entitled ‘Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis’ (Saavedra-Garcia et al., 2017) [24]. Here, we have matched the DAF-16/FOXO3 downstream genes with their respective human orthologues and reviewed the roles of these targeted genes in FA metabolism. The list of genes listed in this article are precisely selected from literature reviews based on their functions in mammalian FA metabolism. The nematode Caenorhabditis elegans gene orthologues of the genes are obtained from WormBase, the online biological database of C. elegans. This dataset has not been uploaded to a public repository yet.

Bezafibrate ameliorates diabetes via reduced steatosis and improved hepatic insulin sensitivity in diabetic TallyHo mice

OBJECTIVE

Recently, we have shown that Bezafibrate (BEZ), the pan-PPAR (peroxisome proliferator-activated receptor) activator, ameliorated diabetes in insulin deficient streptozotocin treated diabetic mice. In order to study whether BEZ can also improve glucose metabolism in a mouse model for fatty liver and type 2 diabetes, the drug was applied to TallyHo mice.

METHODS

TallyHo mice were divided into an early (ED) and late (LD) diabetes progression group and both groups were treated with 0.5% BEZ (BEZ group) or standard diet (SD group) for 8 weeks. We analyzed plasma parameters, pancreatic beta-cell morphology, and mass as well as glucose metabolism of the BEZ-treated and control mice. Furthermore, liver fat content and composition as well as hepatic gluconeogenesis and mitochondrial mass were determined.

RESULTS

Plasma lipid and glucose levels were markedly reduced upon BEZ treatment, which was accompanied by elevated insulin sensitivity index as well as glucose tolerance, respectively. BEZ increased islet area in the pancreas. Furthermore, BEZ treatment improved energy expenditure and metabolic flexibility. In the liver, BEZ ameliorated steatosis, modified lipid composition and increased mitochondrial mass, which was accompanied by reduced hepatic gluconeogenesis.

CONCLUSIONS

Our data showed that BEZ ameliorates diabetes probably via reduced steatosis, enhanced hepatic mitochondrial mass, improved metabolic flexibility and elevated hepatic insulin sensitivity in TallyHo mice, suggesting that BEZ treatment could be beneficial for patients with NAFLD and impaired glucose metabolism.

Circulating FGF21 in humans is potently induced by short term overfeeding of carbohydrates

Objective

Fibroblast-growth factor 21 (FGF21) is thought to be important in metabolic regulation. Recently, low protein diets have been shown to increase circulating FGF21 levels. However, when energy contribution from dietary protein is lowered, other macronutrients, such as carbohydrates, must be increased to meet eucaloric balance. This raises the possibility that intake of a diet rich in carbohydrates may induce an increase in plasma FGF21 levels per se. Here we studied the role of dietary carbohydrates on the levels of circulating FGF21 and concomitant physiologic effects by feeding healthy men a carbohydrate rich diet without reducing protein intake.

Methods

A diet enriched in carbohydrates (80 E% carbohydrate; CHO) and a eucaloric control diet (CON) were provided to nine healthy men for three days. The energy intake during the CHO diet was increased (+75% energy) to ensure similar dietary protein intake in CHO and CON. To control for the effect of caloric surplus, we similarly overfed (+75% energy) the same subjects for three days with a fat-rich diet (78 E% fat; FAT), consisting of primarily unsaturated fatty acids. The three diets were provided in random order.

Results

After CHO, plasma FGF21 concentration increased 8-fold compared to CON (329 ± 99 vs. 39 ± 9 pg ml⁻¹, p < 0.05). In contrast, after FAT only a non-significant tendency (p = 0.073) to an increase in plasma FGF21 concentration was found. The increase in FGF21 concentration after CHO correlated closely (r = 0.88, p < 0.01) with increased leg glucose uptake (62%, p < 0.05) and increased hepatic glucose production (17%, p < 0.01), indicating increased glucose turnover. Plasma fatty acid (FA) concentration was decreased by 68% (p < 0.01), supported by reduced subcutaneous adipose tissue HSL Ser⁶⁶⁰ phosphorylation (p < 0.01) and perilipin 1 protein content (p < 0.01), pointing to a suppression of adipose tissue lipolysis. Concomitantly, a 146% increase in the plasma marker of hepatic de novo lipogenesis C16:1 n−7 FA (p < 0.01) was observed together with 101% increased plasma TG concentration (p < 0.001) in association with CHO intake and increased plasma FGF21 concentration.

Conclusion

Excess dietary carbohydrate, but not fat, led to markedly increased FGF21 secretion in humans, notably without protein restriction, and affected glucose and lipid homeostais.

•

Dietary carbohydrate excess induces circulating FGF21 8-fold in humans.

•

Increased FGF21 was associated with increased hepatic glucose production and lipogenesis.

•

The induction of FGF21 was associated with increased leg glucose uptake.

•

The induction of FGF21 was accompanied by indices of lower adipose tissue lipolysis.

Atlantic salmon require long-chain n-3 fatty acids for optimal growth throughout the seawater period

The nutritional requirement for n-3 long-chain PUFA in fast-growing Atlantic salmon (Salmo salar) during grow out in the sea is not well documented. Diets were formulated with levels of EPA (20 : 5n-3) and DHA (22 : 6n-3) ranging from 1·3 to 7·4 % of fatty acids (4–24 g/kg feed). Two long-term trials were conducted through the seawater phase, the first at 6 and 12°C, and the second at 12°C. In the first trial, growth at both temperatures was significantly lower in fish fed 1·4 % EPA+DHA of total fatty acids compared with the 5·2 % EPA+DHA group. In the second trial, growth was significantly lower in fish fed 1·3 and 2·7 % compared with 4·4 and 7·4 % EPA + DHA. Fatty acid composition in the fish reflected diet composition, but only after a 7-fold increase in body weight did the fatty acid profile of the fish stabilise according to dietary fatty acids (shown for EPA and DHA). The retention efficiency of DHA increased with decreasing dietary levels, and was 120–190 and 120–200 % in trials 1 and 2, respectively. The retention efficiency of EPA was lower (60–200 %), and values >100 % were only achieved at the lowest dietary levels in both trials. Temperature did not affect fatty acid retention efficiency. These results suggest that Atlantic salmon have a specific requirement for EPA + DHA >2·7 % of fatty acids for optimal long-term growth in seawater, and that short-term growth trials with less weight increase would not show these effects.

A comprehensive lipidomic screen of pancreatic β-cells using mass spectroscopy defines novel features of glucose-stimulated turnover of neutral lipids, sphingolipids and plasmalogens

Objective

Glucose promotes lipid remodelling in pancreatic β-cells, and this is thought to contribute to the regulation of insulin secretion, but the metabolic pathways and potential signalling intermediates have not been fully elaborated.

Methods

Using mass spectrometry (MS) we quantified changes in approximately 300 lipid metabolites in MIN6 β-cells and isolated mouse islets following 1 h stimulation with glucose. Flux through sphingolipid pathways was also assessed in ³H-sphinganine-labelled cells using TLC.

Results

Glucose specifically activates the conversion of triacylglycerol (TAG) to diacylglycerol (DAG). This leads indirectly to the formation of 18:1 monoacylglycerol (MAG), via degradation of saturated/monounsaturated DAG species, such as 16:0_18:1 DAG, which are the most abundant, immediate products of glucose-stimulated TAG hydrolysis. However, 16:0-containing, di-saturated DAG species are a better direct marker of TAG hydrolysis since, unlike the 18:1-containing DAGs, they are predominately formed via this route. Using multiple reaction monitoring, we confirmed that in islets under basal conditions, 18:1 MAG is the most abundant species. We further demonstrated a novel site of glucose to enhance the conversion of ceramide to sphingomyelin (SM) and galactosylceramide (GalCer). Flux and product:precursor analyses suggest regulation of the enzyme SM synthase, which would constitute a separate mechanism for localized generation of DAG in response to glucose. Phosphatidylcholine (PC) plasmalogen (P) species, specifically those containing 20:4, 22:5 and 22:6 side chains, were also diminished in the presence of glucose, whereas the more abundant phosphatidylethanolamine plasmalogens were unchanged.

Conclusion

Our results highlight 18:1 MAG, GalCer, PC(P) and DAG/SM as potential contributors to metabolic stimulus-secretion coupling.

•

Using mass spectroscopy lipidomics we have defined new aspects of glucose simulated lipid turnover in pancreatic beta cells.

•

Glucose directly stimulates triacylglycerol hydrolysis, of which di-saturated diacylglycerol species are excellent markers.

•

C18:1 is the most abundant monacylglycerol, and the one most obviously increased by glucose.

•

Phosphatidylcholine plasmalogens with poly-unsaturated side chains are preferentially decreased by glucose.

•

Glucose specifically enhances the conversion of ceramide to both sphingomyelin and galactosylceramide.

Microscopy tools for the investigation of intracellular lipid storage and dynamics

Background

Excess storage of lipids in ectopic tissues, such as skeletal muscle, liver, and heart, seems to associate closely with metabolic abnormalities and cardiac disease. Intracellular lipid storage occurs in lipid droplets, which have gained attention as active organelles in cellular metabolism. Recent developments in high-resolution microscopy and microscopic spectroscopy have opened up new avenues to examine the physiology and biochemistry of intracellular lipids.

Scope of review

The aim of this review is to give an overview of recent technical advances in microscopy, and its application for the visualization, identification, and quantification of intracellular lipids, with special focus to lipid droplets. In addition, we attempt to summarize the probes currently available for the visualization of lipids.

Major conclusions

The continuous development of lipid probes in combination with the rapid development of microscopic techniques can provide new insights in the role and dynamics of intracellular lipids. Moreover, in situ identification of intracellular lipids is now possible and promises to add a new dimensionality to analysis of lipid biochemistry, and its relation to (patho)physiology.

Rapid and selective manipulation of milk fatty acid composition in mice through the maternal diet during lactation

Dietary fatty acid (FA) composition in early postnatal life can modulate growth and development and later metabolic health. Investigating programming effects of early dietary FA manipulations in rodents may be stressful and complicated due to the need of artificial feeding techniques. It is largely unknown to what extent breast milk (BM) FA composition can be directly manipulated by the diet. We exposed dams to different dietary FA compositions from postnatal day (PN) 2 until PN28. Dams with litters were randomly assigned to control (CTRL), high-medium-chain FA (MCFA), low-linoleic acid (LowLA), high-n-3 long-chain PUFA (n-3LCP) or high-n-3LCP and MCFA (n-3LCP/MCFA) diets, and diets were continued after weaning until PN28. FA compositions were determined in feeds, milk and in erythrocytes. BM MCFA content was independent from dietary MCFA intake. In contrast, the LowLA diet reduced BM LA content by about 50 % compared with the CTRL diet at PN7. BM of dams fed the n-3LCP or n-3LCP/MCFA diet contained about 6-fold more n-3 LCP than BM of the dams fed the CTRL diet at PN7. These changes in milk FA composition established after 5 d of dietary exposure did not further change over the lactation period. At PN28, the erythrocyte FA composition of the male pups correlated with analysed milk FA profiles. In conclusion, manipulation of the diet of lactating mice can strongly and rapidly affect BM FA composition, in particular of n-6 LA and n-3 LCP. Our present findings will facilitate mechanistic studies on the programming of adult metabolic health by dietary FA in the early postnatal period via direct and selective manipulation of the maternal diet.

The cytotoxicity of BAMLET complexes is due to oleic acid and independent of the α-lactalbumin component

•

We synthesized three different BAMLET complexes consisting of oleic acid coupled to bovine α-lactalbumin.

•

Oleic acid micelles alone are tumoricidal at equimolar concentrations of oleic acid bound in the BAMLET complexes.

•

α-Lactalbumin is non-toxic to cells even when delivered to their cytoplasm.

•

Both, BAMLET and oleic acid micelles showed no selective cytotoxicity to cancer cells.

Lipid–protein complexes comprised of oleic acid (OA) non-covalently coupled to human/bovine α-lactalbumin, named HAMLET/BAMLET, display cytotoxic properties against cancer cells. However, there is still a substantial debate about the role of the protein in these complexes. To shed light into this, we obtained three different BAMLET complexes using varying synthesis conditions. Our data suggest that to form active BAMLET particles, OA has to reach critical micelle concentration with an approximate diameter of 250 nm. Proteolysis experiments on BAMLET show that OA protects the protein and is probably located on the surface, consistent with a micelle-like structure. Native or unfolded α-lactalbumin without OA lacked any tumoricidal activity. In contrast, OA alone killed cancer cells with the same efficiency at equimolar concentrations as its formulation as BAMLET. Our data show unequivocally that the cytotoxicity of the BAMLET complex is exclusively due to OA and that OA alone, when formulated as a micelle, is as toxic as the BAMLET complex. The contradictory literature results on the cytotoxicity of BAMLET might be explained by our finding that it was imperative to sonicate the samples to obtain toxic OA.

Mechanism of the development of nonalcoholic steatohepatitis after pancreaticoduodenectomy

Background and aim

It is recognized that nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), may develop after pancreaticoduodenectomy (PD). However, the mechanism of NASH development remains unclear. This study aimed to examine the changes in gene expression associated with NASH occurrence following PD.

Methods

The expression of genes related to fatty acid/triglyceride (FA/TG) metabolism and inflammatory signaling was examined using liver samples obtained from 7 post-PD NASH patients and compared with 6 healthy individuals and 32 conventional NASH patients.

Results

The livers of post-PD NASH patients demonstrated significant up-regulation of the genes encoding CD36, FA-binding proteins 1 and 4, acetyl-coenzyme A carboxylase α, diacylglycerol acyltransferase 2, and peroxisome proliferator-activated receptor (PPAR) γ compared with normal and conventional NASH livers. Although serum apolipoprotein B (ApoB) and TG were decreased in post-PD NASH patients, the mRNAs of ApoB and microsomal TG transfer protein were robustly increased, indicating impaired TG export from the liver as very-low-density lipoprotein (VLDL). Additionally, elevated mRNA levels of myeloid differentiation primary response 88 and superoxide dismutases in post-PD NASH livers suggested significant activation of innate immune response and augmentation of oxidative stress generation.

Conclusions

Enhanced FA uptake into hepatocytes and lipogenesis, up-regulation of PPARγ, and disruption of VLDL excretion into the circulation are possible mechanisms of steatogenesis after PD.

General significance

These results provide a basis for understanding the pathogenesis of NAFLD/NASH following PD.

•

The mechanism of NASH development after pancreaticoduodenectomy (PD) was unclear.

•

The gene expression involved in fatty acid uptake and lipogenesis was increased.

•

PPARγ and its target genes were up-regulated in post-PD NASH livers.

•

Impaired triglyceride excretion from the liver was suggested in post-PD NASH.

•

This study proposes possible mechanisms of steatogenesis after PD.

Asperuloside stimulates metabolic function in rats across several organs under high-fat diet conditions, acting like the major ingredient of Eucommia leaves with anti-obesity activity

Eucommia leaves (Eucommia ulmoides Oliver) contain chlorogenic acid (a caffeic acid derivative) and geniposidic acid and asperuloside (ASP), iridoid glucosides used in beverages. We used a metabolic syndrome rat model, produced by feeding a 35 % high-fat diet (HFD), to examine potential anti-obesity and anti-metabolic syndrome effects and mechanisms of chronic administration of ASP. These effects were compared with Eucommia leaf extract (ELE), the positive control, which exhibits anti-obesity effects. A total of six rats were studied for 3 months in five groups. ASP suppressed body weight, visceral fat weight, food intake and circulating levels of glucose, insulin and lipids, and increased the plasma adiponectin level in rats on a HFD. These effects are similar to those of ELE, except for the influence on the plasma glucose level. RT-PCR studies showed that ASP (like ELE with known anti-obesity effects) diminished isocitrate dehydrogenase 3α, NADH dehydrogenase flavoprotein 1 (Comp I) mRNA and fatty acid synthase levels (white adipose tissue), increased carnitine palmitoyltransferase 1α and acyl-CoA dehydrogenase, very-long-chain mRNA levels (liver), and increased Glut4, citrate synthase, isocitrate dehydrogenase 3α, succinyl CoA synthase, peroxisomal 3-ketoacyl-CoA thiolase, dihydrolipoamide succinyl transferase and succinate dehydrogenase mRNA levels (skeletal muscle) under HFD conditions. Interestingly, ASP administration resulted in significantly increased mRNA levels of uncoupling protein 1 (UCP1) in the brown adipose tissue of HFD-fed rats; ELE did not affect the expression of UCP1. The increased expression of UCP1 may be negated by many ingredients other than ASP in the ELE. These findings suggest that chronic administration of ASP stimulates anti-obesity and anti-metabolic syndrome activity in HFD-fed rats across several organs, similar to ELE administration; thus, ASP may be an important ingredient of ELE.