Biomarkers and subtypes of deranged lipid metabolism in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease(NAFLD)is a heterogeneous and complex disease that is imprecisely diagnosed by liver biopsy.NAFLD covers a spectrum that ranges from simple steatosis,nonalcoholic steatohepatitis(NASH)with varying degrees of fibrosis,to cirrhosis,which is a major risk factor for hepatocellular carcinoma.Lifestyle and eating habit changes during the last century have made NAFLD the most common liver disease linked to obesity,type 2 diabetes mellitus and dyslipidemia,with a global prevalence of 25%.NAFLD arises when the uptake of fatty acids(FA)and triglycerides(TG)from circulation and de novo lipogenesis saturate the rate of FAβ-oxidation and verylow density lipoprotein(VLDL)-TG export.Deranged lipid metabolism is also associated with NAFLD progression from steatosis to NASH,and therefore,alterations in liver and serum lipidomic signatures are good indicators of the disease’s development and progression.This review focuses on the importance of the classification of NAFLD patients into different subtypes,corresponding to the main alteration(s)in the major pathways that regulate FA homeostasis leading,in each case,to the initiation and progression of NASH.This concept also supports the targeted intervention as a key approach to maximize therapeutic efficacy and opens the door to the development of precise NASH treatments.

Methionine adenosyltransferases in liver cancer

Methionine adenosyltransferases(MATs)are essential enzymes for life as they produce S-adenosylmethionine(SAMe),the biological methyl donor required for a plethora of reactions within the cell.Mammalian systems express two genes,MAT1A and MAT2A,which encode for MATα1 and MATα2,the catalytic subunits of the MAT isoenzymes,respectively.A third gene MAT2B,encodes a regulatory subunit known as MATβwhich controls the activity of MATα2.MAT1A,which is mainly expressed in hepatocytes,maintains the differentiated state of these cells,whilst MAT2A and MAT2B are expressed in extrahepatic tissues as well as non-parenchymal cells of the liver(e.g.,hepatic stellate and Kupffer cells).The biosynthesis of SAMe is impaired in patients with chronic liver disease and liver cancer due to decreased expression and inactivation of MATα1.A switch from MAT1A to MAT2A/MAT2B occurs in multiple liver diseases and during liver growth and dedifferentiation,but this change in the expression pattern of MATs results in reduced hepatic SAMe level.Decades of study have utilized the Mat1a-knockout(KO)mouse that spontaneously develops non-alcoholic steatohepatitis(NASH)and hepatocellular carcinoma(HCC)to elucidate a variety of mechanisms by which MAT proteins dysregulation contributes to liver carcinogenesis.An increasing volume of work indicates that MATs have SAMe-independent functions,distinct interactomes and multiple subcellular localizations.Here we aim to provide an overview of MAT biology including genes,isoenzymes and their regulation to provide the context for understanding consequences of their dysregulation.We will highlight recent breakthroughs in the field and underscore the importance of MAT’s in liver tumorigenesis as well as their potential as targets for cancer therapy.

Arachidyl amido cholanoic acid improves liver glucose and lipid homeostasis in nonalcoholic steatohepatitis via AMPK and mTOR regulation

BACKGROUND Arachidyl amido cholanoic acid(Aramchol)is a potent downregulator of hepatic stearoyl-CoA desaturase 1(SCD1)protein expression that reduces liver triglycerides and fibrosis in animal models of steatohepatitis.In a phase IIb clinical trial in patients with nonalcoholic steatohepatitis(NASH),52 wk of treatment with Aramchol reduced blood levels of glycated hemoglobin A1c,an indicator of glycemic control.AIM To assess lipid and glucose metabolism in mouse hepatocytes and in a NASH mouse model[induced with a 0.1%methionine and choline deficient diet(0.1MCD)]after treatment with Aramchol.METHODS Isolated primary mouse hepatocytes were incubated with 20μmol/L Aramchol or vehicle for 48 h.Subsequently,analyses were performed including Western blot,proteomics by mass spectrometry,and fluxomic analysis with 13C-uniformly labeled glucose.For the in vivo part of the study,male C57BL/6J mice were randomly fed a control or 0.1MCD for 4 wk and received 1 or 5 mg/kg/d Aramchol or vehicle by intragastric gavage for the last 2 wk.Liver metabolomics were assessed using ultra-high-performance liquid chromatography-time of flight-MS for the determination of glucose metabolism-related metabolites.RESULTS Combination of proteomics and Western blot analyses showed increased AMPK activity while the activity of nutrient sensor mTORC1 was decreased by Aramchol in hepatocytes.This translated into changes in the content of their downstream targets including proteins involved in fatty acid(FA)synthesis and oxidation[PACCα/β(S79),SCD1,CPT1A/B,HADHA,and HADHB],oxidative phosphorylation(NDUFA9,NDUFB11,NDUFS1,NDUFV1,ETFDH,and UQCRC2),tricarboxylic acid(TCA)cycle(MDH2,SUCLA2,and SUCLG2),and ribosome(P-p70S6K[T389]and P-S6[S235/S236]).Flux experiments with 13Cuniformely labeled glucose showed that TCA cycle cataplerosis was reduced by Aramchol in hepatocytes,as indicated by the increase in the number of rounds that malate remained in the TCA cycle.Finally,liver metabolomic analysis showed that glucose homeostasis was improved by Aramchol in 0.1MCD fed mice in a dose-dependent manner,showing normalization of glucose,G6P,F6P,UDP-glucose,and Rbl5P/Xyl5P.CONCLUSION Aramchol exerts its effect on glucose and lipid metabolism in NASH through activation of AMPK and inhibition of mTORC1,which in turn activate FAβ-oxidation and oxidative phosphorylation.

Early treatment efficacy of S-adenosylmethionine in patients with intrahepatic cholestasis: A systematic review

BACKGROUND S-adenosylmethionine(AdoMet)is a metabolically pleiotropic molecule used to treat intrahepatic cholestasis(IHC)and chronic liver diseases.While the efficacy of AdoMet has been demonstrated previously,it has not been systematically investigated within the early weeks of treatment.AIM To systematically review the early treatment efficacy of AdoMet in adult patients with IHC.METHODS Studies reporting the efficacy of intravenous,intramuscular,or oral forms of AdoMet within 8 wk of treatment initiation were considered;three randomized and six non-randomized studies were eligible for inclusion(PROSPERO registration number CRD42018090936).Of the three randomized studies,two were double-blind and placebo-controlled,and one was comparator-controlled with unclear blinding and a relatively high risk of bias.Mean serum levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),and gamma-glutamyl transferase(γGT)following AdoMet treatment vs placebo,comparator,or baseline were summarized to determine differences in liver enzymes.Changes in patient-reported clinical symptoms of cholestasis were also summarized.RESULTS Both placebo-controlled randomized studies reported significant reductions in serum ALT levels with AdoMet vs placebo within 2 wk.One of these also reported significant ALP reductions,and the other reported significant AST andγGT reductions within 2 wk.The comparator-controlled randomized study,which had a number of notable limitations,reported significant reductions in serum ALT and AST levels with AdoMet vs potassium magnesium aspartate within 4 wk,but not within2 wk.All of the non-randomized studies(4/4)that investigated ALT,AST,ALP and/orγGT reported significant reductions in at least two of these parameters within 2 wk.Of the five studies that evaluated fatigue,reductions were observed within 2 wk in one randomized and two nonrandomized studies.The remaining two non-randomized studies reported improvements in fatigue within 6 and 8 wk.Of the four studies reporting symptoms of depression,two non-randomized studies observed improvements within 2 wk and the other two observed improvements within 17 d and 8 wk.CONCLUSION Data from both randomized and non-randomized studies suggest that AdoMet improves some biochemical liver parameters and symptoms of cholestasis within 2 wk,with further improvements observed in some studies after 4 and 8 wk of treatment.

Serotonin type 3 receptor subunit gene polymorphisms associated with psychosomatic symptoms in irritable bowel syndrome:A multicenter retrospective study

BACKGROUND Single-nucleotide polymorphisms(SNPs)of the serotonin type 3 receptor subunit(HTR3)genes have been associated with psychosomatic symptoms,but it is not clear whether these associations exist in irritable bowel syndrome(IBS).AIM To assess the association of HTR3 polymorphisms with depressive,anxiety,and somatization symptoms in individuals with IBS.METHODS In this retrospective study,623 participants with IBS were recruited from five specialty centers in Germany,Sweden,the United States,the United Kingdom,and Ireland.Depressive,anxiety,and somatization symptoms and sociodemographic characteristics were collected.Four functional SNPs—HTR3A c.-42C>T,HTR3B c.386A>C,HTR3C c.489C>A,and HTR3E c.*76G>A—were genotyped and analyzed using the dominant and recessive models.We also performed separate analyses for sex and IBS subtypes.SNP scores were calculated as the number of minor alleles of the SNPs above.The impact of HTR3C c.489C>A was tested by radioligand-binding and calcium influx assays.RESULTS Depressive and anxiety symptoms significantly worsened with increasing numbers of minor HTR3C c.489C>A alleles in the dominant model(F_(depressive)=7.475,P_(depressive)=0.006;F_(anxiety)=6.535,P_(anxiety)=0.011).A higher SNP score(range 0-6)was linked to a worsened depressive symptoms score(F=7.710,P-linear trend=0.006)in IBS.The potential relevance of the HTR3C SNP was corroborated,showing changes in the expression level of 5-HT3AC variant receptors.CONCLUSION We have provided the first evidence that HTR3C c.489C>A is involved in depressive and anxiety symptoms in individuals with IBS.The SNP score indicated that an increasing number of minor alleles is linked to the worsening of depressive symptoms in IBS.

Engineering hyaluronic acid-based nanoassemblies for monoclonal antibody delivery-design,characterization,and biological insights

The current spotlight of cancer therapeutics is shifting towards personalized medicine with the widespread use of monoclonal antibodies(mAbs).Despite their increasing potential,mAbs have an intrinsic limitation related to their inability to cross cell membranes and reach intracellular targets.Nanotechnology offers promising solutions to overcome this limitation,however,formulation challenges remain.These challenges are the limited loading capacity(often insufficient to achieve clinical dosing),the complex formulation methods,and the insufficient characterization of mAb-loaded nanocarriers.Here,we present a new nanocarrier consisting of hyaluronic acid-based nanoassemblies(HANAs)specifically designed to entrap mAbs with a high efficiency and an outstanding loading capacity(50%,w/w).HANAs composed by an mAb,modified HA and phosphatidylcholine(PC)resulted in sizes of~100 nm and neutral surface charge.Computational modeling identified the principal factors governing the high affinity of mAbs with the amphiphilic HA and PC.HANAs composition and structural configuration were analyzed using the orthogonal techniques cryogenic transmission electron microscopy(cryo-TEM),asymmetrical flow field-flow fractionation(AF4),and small-angle X-ray scattering(SAXS).These techniques provided evidence of the formation of core-shell nanostructures comprising an aqueous core surrounded by a bilayer consisting of phospholipids and amphiphilic HA.In vitro experiments in cancer cell lines and macrophages confirmed HANAs’low toxicity and ability to transport mAbs to the intracellular space.The reproducibility of this assembling process at industrial-scale batch sizes and the long-term stability was assessed.In conclusion,these results underscore the suitability of HANAs technology to load and deliver biologicals,which holds promise for future clinical translation.

Highlights of the 2nd International Symposium on Tribbles and Diseases: tribbles tremble in therapeutics for immunity, metabolism, fundamental cell biology and cancer

The Tribbles(TRIB) family of pseudokinase proteins has been shown to play key roles in cell cycle, metabolic diseases, chronic inflammatory disease, and cancer development. A better understanding of the mechanisms of TRIB pseudokinases could provide new insights for disease development and help promote TRIB proteins as novel therapeutic targets for drug discovery. At the 2 nd International Symposium on Tribbles and Diseases held on May 7–9, 2018 in Beijing, China, a group of leading Tribbles scientists reported their findings and ongoing studies about the effects of the different TRIB proteins in the areas of immunity, metabolism, fundamental cell biology and cancer. Here, we summarize important and insightful overviews from 4 keynote lectures, 13 plenary lectures and 8 short talks that took place during this meeting. These findings may offer new insights for the understanding of the roles of TRIB pseudokinases in the development of various diseases.

Interaction of the α2A domain of integrin with small collagen fragments

We here present a detailed study of the ligand-receptor interactions between single and triple-helical strands of collagen and the α2A domain of integrin(α2A),providing valuable new insights into the mechanisms and dynamics of collagen-integrin binding at a sub-molecular level.The occurrence of single and triple-helical strands of the collagen fragments was scrutinized with atom force microscopy(AFM)techniques.Strong interactions of the triple-stranded fragments comparable to those of collagen can only be detected for the 42mer triple-helical collagen-like peptide under study(which contains 42 amino acid residues per strand)by solid phase assays as well as by surface plasmon resonance(SPR)measurements.However,changes in NMR signals during titration and characteristic saturation transfer difference(STD)NMR signals are also detectable whenα2A is added to a solution of the 21mer single-stranded collagen fragment.Molecular dynamics(MD)simulations employing different sets of force field parameters were applied to study the interaction between triple-helical or single-stranded collagen fragments withα2A.It is remarkable that even single-stranded collagen fragments can form various complexes withα2A showing significant differences in the complex stability with identical ligands.The results of MD simulations are in agreement with the signal alterations in our NMR experiments,which are indicative of the formation of weak complexes between single-stranded collagen andα2A in solution.These results provide useful information concerning possible interactions ofα2A with small collagen fragments that are of relevance to the design of novel therapeutic A-domain inhibitors.