Metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing both in numbers and severity worldwide. Non-invasive alternatives to liver biopsy, particularly for the detection of metabolic dysfunction-associated steatohepatitis (MASH), have proven difficult to establish. We aimed to assess whether quantitative MRI (qMRI) alone and in combination with laboratory and anthropometric measurements and other non-invasive tests (NITs) can detect stages of MASLD. In this single-center prospective cohort study, 91 participants with hepatic steatosis on ultrasound or vibration-controlled transient elastography were enrolled in the outpatient clinics between September 2018 and January 2024. Patients underwent blood sampling, qMRI and liver biopsy. Non-invasive parameters were correlated with histopathology in all 91 participants, of whom 37 were reported previously. Prediction models for advanced steatosis (S3), MASH, fibro-MASH (S ≥ 1, lobular inflammation ≥ 1, hepatocyte ballooning ≥ 1 and F ≥ 2), significant (≥ F2) and advanced (≥ F3) fibrosis were designed based on 88 MASLD patients. MR elastography (MRE)-derived elasticity (MRE-G’), MRE-derived stiffness (MRE-Gabs) and LiverMultiScan® iron-corrected T1 (cT1) correlated with hepatocyte ballooning (Spearman’s R: 0.45 (p < 0.001); 0.42 (p < 0.001); 0.38 (p < 0.001)). Prediction models for ≥ F3 outperformed MAF5 and FIB4, but did not outperform ELF or NFS. A model combining cT1, MRE-G’, aspartate aminotransferase and alanine aminotransferase yielded an AUC of 0.83 (95

Metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing in both prevalence and severity, highlighting the need for non-invasive biomarkers to assess disease activity. Extracellular vesicles (EVs), which carry molecular cargo from their cells of origin, hold promise as accessible biomarkers. We performed proteomic profiling of plasma-derived EVs from 70 patients with MASLD to identify protein signatures associated with key histological features (steatosis, metabolic dysfunction-associated steatohepatitis (MASH), and fibrosis). These proteins were subsequently correlated with magnetic resonance (MR)-based liver imaging. Plasma EV protein profile differed between mild (S1) and advanced steatosis (S3). H4C1, OIT3, and ANPEP were elevated in S3, while CCDC25 and KLHL41 were decreased (|log2 fold change| > 1, p < 0.05). KLHL41 had a weak-to-moderate correlation with proton density fat fraction (PDFF) (R = −0.34, p = 0.016). GP1BA was upregulated in MASH (log2 fold change = 1.13, p = 0.03) but showed weak correlation with cT1, an imaging parameter for steatohepatitis (R = 0.22, p = 0.173). In fibrosis, complement component 7 (C7) was elevated in advanced (≥F3) vs. mild fibrosis (

This randomized, double-blind, placebo-controlled trial investigated the impact of 14-day Anaerobutyricum soehngenii L2-7 supplementation on postprandial glucose levels in 25 White Dutch males with type 2 diabetes (T2D) on stable metformin therapy. The primary endpoint was the effect of A. soehngenii versus placebo on glucose excursions and variability as determined by continuous glucose monitoring. Secondary endpoints were changes in ambulatory 24-h blood pressure, incretins, circulating metabolites and excursions of plasma short-chain fatty acids (SCFAs) and bile acids upon a standardized meal. Results showed that A. soehngenii supplementation for 14 days significantly improved glycemic variability and mean arterial blood pressure, without notable changes in SCFAs, bile acids, incretin levels, or anthropometric parameters as compared to placebo-treated controls. Although well-tolerated and effective in improving glycemic control in the intervention group, further research in larger and more diverse populations is needed to generalize these findings.

Individuals with nonalcoholic fatty liver disease (NAFLD) have an altered gut microbiota composition. Moreover, hepatic DNA methylation may be altered in the state of NAFLD. Using a fecal microbiota transplantation (FMT) intervention, we aimed to investigate whether a change in gut microbiota composition relates to altered liver DNA methylation in NAFLD. Moreover, we assessed whether plasma metabolite profiles altered by FMT relate to changes in liver DNA methylation. Twenty-one individuals with NAFLD underwent three 8-weekly vegan allogenic donor (n = 10) or autologous (n = 11) FMTs. We obtained hepatic DNA methylation profiles from paired liver biopsies of study participants before and after FMTs. We applied a multi-omics machine learning approach to identify changes in the gut microbiome, peripheral blood metabolome and liver DNA methylome, and analyzed cross-omics correlations. Vegan allogenic donor FMT compared to autologous FMT induced distinct differential changes in I) gut microbiota profiles, including increased abundance of Eubacterium siraeum and potential probiotic Blautia wexlerae; II) plasma metabolites, including altered levels of phenylacetylcarnitine (PAC) and phenylacetylglutamine (PAG) both from gut-derived phenylacetic acid, and of several choline-derived long-chain acylcholines; and III) hepatic DNA methylation profiles, most importantly in Threonyl-TRNA Synthetase 1 (TARS) and Zinc finger protein 57 (ZFP57). Multi-omics analysis showed that Gemmiger formicillis and Firmicutes bacterium_CAG_170 positively correlated with both PAC and PAG. E siraeum negatively correlated with DNA methylation of cg16885113 in ZFP57. Alterations in gut microbiota composition by FMT caused widespread changes in plasma metabolites (e.g. PAC, PAG, and choline-derived metabolites) and liver DNA methylation profiles in individuals with NAFLD. These results indicate that FMTs might induce metaorganismal pathway changes, from the gut bacteria to the liver.

Recent literature suggests that tri-exponential models may provide additional information and fit liver intravoxel incoherent motion (IVIM) data more accurately than conventional bi-exponential models. However, voxel-wise fitting of IVIM results in noisy and unreliable parameter maps. For bi-exponential IVIM, neural networks (NN) were able to produce superior parameter maps than conventional least-squares (LSQ) generated images. Hence, to improve parameter map quality of tri-exponential IVIM, we developed an unsupervised physics-informed deep neural network (IVIM3-NET). We assessed its performance in simulations and in patients with non-alcoholic fatty liver disease (NAFLD) and compared outcomes with bi-exponential LSQ and NN fits and tri-exponential LSQ fits. Scanning was performed using a 3.0T free-breathing multi-slice diffusion-weighted single-shot echo-planar imaging sequence with 18 b-values. Images were analysed for visual quality, comparing the bi- and tri-exponential IVIM models for LSQ fits and NN fits using parameter-map signal-to-noise ratios (SNR) and adjusted R2. IVIM parameters were compared to histological fibrosis, disease activity and steatosis grades. Parameter map quality improved with bi- and tri-exponential NN approaches, with a significant increase in average parameter-map SNR from 3.38 to 5.59 and 2.45 to 4.01 for bi- and tri-exponential LSQ and NN models respectively. In 33 out of 36 patients, the tri-exponential model exhibited higher adjusted R2 values than the bi-exponential model. Correlating IVIM data to liver histology showed that the bi- and tri-exponential NN outperformed both LSQ models for the majority of IVIM parameters (10 out of 15 significant correlations). Overall, our results support the use of a tri-exponential IVIM model in NAFLD. We show that the IVIM3-NET can be used to improve image quality compared to a tri-exponential LSQ fit and provides promising correlations with histopathology similar to the bi-exponential neural network fit, while generating potentially complementary additional parameters.

Background Recent studies demonstrate that a Mediterranean diet has beneficial metabolic effects in metabolic syndrome subjects. Since we have shown that fecal microbiota transplantation (FMT) from lean donors exerts beneficial effects on insulin sensitivity, in the present trial, we investigated the potential synergistic effects on insulin sensitivity of combining a Mediterranean diet with donor FMT in subjects with metabolic syndrome. Design Twenty-four male subjects with metabolic syndrome were put on a Mediterranean diet and after a 2-week run-in phase, the subjects were randomized to either lean donor (n = 12) or autologous (n = 12) FMT. Changes in the gut microbiota composition and bacterial strain engraftment after the 2-week dietary regimens and 6 weeks post-FMT were the primary endpoints. The secondary objectives were changes in glucose fluxes (both hepatic and peripheral insulin sensitivity), postprandial plasma incretin (GLP-1) levels, subcutaneous adipose tissue inflammation, and plasma metabolites. Results Consumption of the Mediterranean diet resulted in a reduction in body weight, HOMA-IR, and lipid levels. However, no large synergistic effects of combining the diet with lean donor FMT were seen on the gut microbiota diversity after 6 weeks. Although we did observe changes in specific bacterial species and plasma metabolites, no significant beneficial effects on glucose fluxes, postprandial incretins, or subcutaneous adipose tissue inflammation were detected. Conclusions In this small pilot randomized controlled trial, no synergistic beneficial metabolic effects of combining a Mediterranean diet with lean donor FMT on glucose metabolism were achieved. However, we observed engraftment of specific bacterial species. Future trials are warranted to test the combination of other microbial interventions and diets in metabolic syndrome.

OBJECTIVE:Although gut dysbiosis is increasingly recognised as a pathophysiological component of metabolic syndrome (MetS), the role and mode of action of specific gut microbes in metabolic health remain elusive. Previously, we identified the commensal butyrogenic Anaerobutyricum soehngenii to be associated with improved insulin sensitivity in subjects with MetS. In this proof-of-concept study, we investigated the potential therapeutic effects of A. soehngenii L2-7 on systemic metabolic responses and duodenal transcriptome profiles in individuals with MetS.DESIGN:In this randomised double-blind placebo-controlled cross-over study, 12 male subjects with MetS received duodenal infusions of A. soehngenii/ placebo and underwent duodenal biopsies, mixed meal tests (6 hours postinfusion) and 24-hour continuous glucose monitoring.RESULTS:A. soehngenii treatment provoked a markedly increased postprandial excursion of the insulinotropic hormone glucagon-like peptide 1 (GLP-1) and an elevation of plasma secondary bile acids, which were positively associated with GLP-1 levels. Moreover, A. soehngenii treatment robustly shaped the duodenal expression of 73 genes, with the highest fold induction in the expression of regenerating islet-protein 1B (REG1B)-encoding gene. Strikingly, duodenal REG1B expression positively correlated with GLP-1 levels and negatively correlated with peripheral glucose variability, which was significantly diminished in the 24 hours following A. soehngenii intake. Mechanistically, Reg1B expression is induced upon sensing butyrate or bacterial peptidoglycan. Importantly, A. soehngenii duodenal administration was safe and well tolerated.CONCLUSIONS:A single dose of A. soehngenii improves peripheral glycaemic control within 24 hours; it specifically stimulates intestinal GLP-1 production and REG1B expression. Further studies are needed to delineate the specific pathways involved in REG1B induction and function in insulin sensitivity.TRIAL REGISTRATION NUMBER:NTR-NL6630.

Editorial for “Assessment of Imaging Modalities Against Liver Biopsy in Nonalcoholic Fatty Liver Disease: The Amsterdam NAFLD-NASH Cohort” Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide with a recent study suggesting a prevalence of 38% in the United States. While the disease is reaching epidemic levels, there is still no recognized pharmacological treatment and there is a massive drive to address this unmet clinical need. Histologically assessed fibrosis and resolution of nonalcoholic steatohepatitis (NASH) remain the only surrogate endpoints accepted by the regulators for studies in patients without cirrhosis. Furthermore, the presence of NASH with significant fibrosis or with cirrhosis is a requirement for inclusion in clinical trials. The limitations of liver biopsy are therefore impeding drug development programs due to high screen failure rates, patient reluctance to participate, and higher numbers of patients needed to achieve sufficient statistical power. Noninvasive biomarkers of liver fibrosis and NASH that could be used instead of liver biopsy for the purposes of clinical trials could therefore revolutionize the field. Magnetic resonance techniques, such as magnetic resonance elastography, proton density fat fraction (PDFF) mapping, and T1 mapping, are attractive as they offer noninvasive assessment and potentially whole-liver coverage eliminating sampling variability. There are now extensive data to support some of these techniques as noninvasive measures of fibrosis, but noninvasive assessment of NASH remains largely unfulfilled. Liver stiffness measurements (LSM) are now routinely carried out using ultrasound-based vibration-controlled transient elastography (VCTE). Newer VCTE machines can provide controlled attenuation parameter (CAP) readings of liver steatosis in addition to LSM. CAP measurements are approximating the attenuation coefficient of ultrasound in the liver, and as this coefficient is different based on the tissue composition, it is expected to have a dependence on the amount of fat present in the hepatocytes. However, it is still unclear to what extent CAP measurements alone can be used to assess steatosis grades. While correlation between CAP and steatosis grade has been reported, some also show a lack of significant difference between CAP measurements in patients with steatosis grades 2 and 3, or even between grades 1 and 2. This variable performance in diagnosing steatosis grades coupled with cut-offs that are often very close to each other with overlapping confidence intervals means that CAP cannot yet be used as an easy, point-of-care method of determining severity of steatosis. In this issue of JMRI, Troelstra et al present the initial results from the Amsterdam NAFLD-NASH cohort (ANCHOR) study. The investigators aim to improve the noninvasive diagnosis and follow-up of individuals with various grades and stages of NAFLD. Results in the first 37 subjects describe the use of multiparametric magnetic resonance imaging (MRI) to predict NAFL vs. NASH, the degree of steatosis, the degree of lobular inflammation and hepatocyte ballooning, and the degree of fibrosis. Overall, the results presented indicate that multiparametric MRI is a promising noninvasive method for the accurate assessment of steatosis and fibrosis severity, with the potential to distinguish between simple hepatic steatosis and NASH. Troelstra et al also found that CAP measurements did not correlate with histological steatosis grade while MRS and two measures of PDFF did correlate significantly with histological steatosis. The study is well conducted, and these results add to the growing body of studies that develop combinations of imaging biomarkers and, potentially, plasma biomarkers to predict the presence of NASH, the inflammation activity grade, and the fibrosis stage in subjects with NAFLD. A major limitation is the limited number of subjects included and the lack of spread in the subjects’ SAF scores with a concentration of subjects with steatosis grade 2, inflammation activity grade A1-2, and fibrosis stage F2. However, recruitment in ANCHOR is ongoing and future results when more subjects have been recruited are eagerly anticipated.

Gut microbiota dysbiosis has been repeatedly observed in obesity and type 2 diabetes mellitus, two metabolic diseases strongly intertwined with non-alcoholic fatty liver disease (NAFLD). Animal studies have demonstrated a potential causal role of gut microbiota in NAFLD. Human studies have started to describe microbiota alterations in NAFLD and have found a few consistent microbiome signatures discriminating healthy individuals from those with NAFLD, non-alcoholic steatohepatitis or cirrhosis. However, patients with NAFLD often present with obesity and/or insulin resistance and type 2 diabetes mellitus, and these metabolic confounding factors for dysbiosis have not always been considered. Patients with different NAFLD severity stages often present with heterogeneous lesions and variable demographic characteristics (including age, sex and ethnicity), which are known to affect the gut microbiome and have been overlooked in most studies. Finally, multiple gut microbiome sequencing tools and NAFLD diagnostic methods have been used across studies that could account for discrepant microbiome signatures. This Review provides a broad insight into microbiome signatures for human NAFLD and explores issues with disentangling these signatures from underlying metabolic disorders. More advanced metagenomics and multi-omics studies using system biology approaches are needed to improve microbiome biomarkers. The gut microbiota has been linked to non-alcoholic fatty liver disease (NAFLD), but metabolic confounding factors, such as obesity and diabetes, complicate analysis. This Review provides a broad insight into microbiome signatures for human NAFLD and explores issues with disentangling them from underlying metabolic disorders.

The intestinal microbiota has been linked to the development and prevalence of steatohepatitis in humans. Interestingly, steatohepatitis is significantly lower in individuals taking a plant-based, low-animal-protein diet, which is thought to be mediated by gut microbiota. However, data on causality between these observations in humans is scarce. In this regard, fecal microbiota transplantation (FMT) using healthy donors is safe and is capable of changing microbial composition in human disease. We therefore performed a double-blind randomized controlled proof-of-principle study in which individuals with hepatic steatosis on ultrasound were randomized to two study arms: lean vegan donor (allogenic n = 10) or own (autologous n = 11) FMT. Both were performed three times at 8-week intervals. A liver biopsy was performed at baseline and after 24 weeks in every subject to determine histopathology (Nonalcoholic Steatohepatitis Clinical Research Network) classification and changes in hepatic gene expression based on RNA sequencing. Secondary outcome parameters were changes in intestinal microbiota composition and fasting plasma metabolomics. We observed a trend toward improved necro-inflammatory histology, and found significant changes in expression of hepatic genes involved in inflammation and lipid metabolism following allogenic FMT. Intestinal microbial community structure changed following allogenic FMT, which was associated with changes in plasma metabolites as well as markers of . Conclusion: Allogenic FMT using lean vegan donors in individuals with hepatic steatosis shows an effect on intestinal microbiota composition, which is associated with beneficial changes in plasma metabolites and markers of steatohepatitis.

The gut microbiota constitutes an important modulator of metabolic heath and an unbalanced microbiota is increasingly recognized as an important risk factor for metabolic disorders, such as obesity, insulin resistance and type 2 diabetes. Seeking for novel treatments to counteract insulin resistance and metabolic disturbances in obese subjects, we explore whether delivering a protective commensal bacteria (Anaerobutyricum soehngenii L2-7) directly into the small intestine of treatment-naïve subjects with metabolic syndrome would ameliorate glucose metabolism (NTR NL6630). We previously identified this butyrate-producing intestinal commensal to be associated with improved insulin sensitivity in metabolic syndrome subjects. Herein, we found that a single-dose of duodenal infusion containing A. soehngenii improved peripheral glucose control and stimulated the secretion of the hormone GLP-1, which is reported to positively act on both insulin secretion and sensitivity. Moreover, by RNA-seq, we found that A. soehngenii-treatment triggered a prominent alteration of the duodenal transcriptome with 73 genes being differentially expressed. Among these, the expression of regenerating islet-protein 1B-encoding gene (REG1B) was the most significantly unregulated by A. soehngenii administration. Strikingly, duodenal REG1B expression negatively correlated with peripheral glucose variability, which was significantly diminished by A. soehngeniiduodenal infusion. Altogether our findings disclose that a single-dose of A. soehngenii is sufficient to greatly impact the duodenal transcriptional profile and ameliorate glucose metabolism in metabolic syndrome individuals, likely through induction of intestinal GLP-1 production. Nonetheless, further studies are needed to delineate the specific pathways involved in induction of REG1B and GLP-1. Notably, duodenal administration of A. soehngenii was also safe and well-tolerated.

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice.

The goal of this study was to develop and validate a noninvasive imaging tool to visualize the in vivo behavior of high-density lipoprotein (HDL) by using positron emission tomography (PET), with an emphasis on its plaque-targeting abilities. HDL is a natural nanoparticle that interacts with atherosclerotic plaque macrophages to facilitate reverse cholesterol transport. HDL-cholesterol concentration in blood is inversely associated with risk of coronary heart disease and remains one of the strongest independent predictors of incident cardiovascular events. Discoidal HDL nanoparticles were prepared by reconstitution of its components apolipoprotein A-I (apo A-I) and the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine. For radiolabeling with zirconium-89 ( 89 Zr), the chelator deferoxamine B was introduced by conjugation to apo A-I or as a phospholipid-chelator (1,2-distearoyl-sn-glycero-3-phosphoethanolamine–deferoxamine B). Biodistribution and plaque targeting of radiolabeled HDL were studied in established murine, rabbit, and porcine atherosclerosis models by using PET combined with computed tomography (PET/CT) imaging or PET combined with magnetic resonance imaging. Ex vivo validation was conducted by radioactivity counting, autoradiography, and near-infrared fluorescence imaging. Flow cytometric assessment of cellular specificity in different tissues was performed in the murine model. We observed distinct pharmacokinetic profiles for the two 89 Zr-HDL nanoparticles. Both apo A-I- and phospholipid-labeled HDL mainly accumulated in the kidneys, liver, and spleen, with some marked quantitative differences in radioactivity uptake values. Radioactivity concentrations in rabbit atherosclerotic aortas were 3- to 4-fold higher than in control animals at 5 days’ post-injection for both 89 Zr-HDL nanoparticles. In the porcine model, increased accumulation of radioactivity was observed in lesions by using in vivo PET imaging. Irrespective of the radiolabel’s location, HDL nanoparticles were able to preferentially target plaque macrophages and monocytes. 89 Zr labeling of HDL allows study of its in vivo behavior by using noninvasive PET imaging, including visualization of its accumulation in advanced atherosclerotic lesions. The different labeling strategies provide insight on the pharmacokinetics and biodistribution of HDL’s main components (i.e., phospholipids, apo A-I).

Elevated nonfasting TG-rich lipoprotein levels are a risk factor for CVD. To further evaluate the relevance of LDL-receptor (LDLr) pathway and heparan sulfate proteoglycans (HSPGs) in TG homeostasis, we analyzed fasting and postprandial TG levels in mice bearing combined heterozygous mutations in both Exostosin (Ext) 1 and Ldlr, in subjects with hereditary multiple exostosis (HME) due to a heterozygous loss-of-function mutation in EXT1 or EXT2 (N = 13), and in patients with heterozygous mutations in LDLR [familial hypercholesterolemia (FH)] and SNPs in major HSPG-related genes (n = 22). Mice bearing a homozygous mutation in hepatic Ext1 exhibited elevated plasma TGs similar to mice lacking other key enzymes involved in HSPG assembly. Compound heterozygous mice lacking Ldlr and Ext1 showed synergy on plasma TG accumulation and postprandial clearance. In human subjects, a trend was observed in HME patients toward reduced postprandial TG clearance with a concomitant reduction in chylomicron clearance [area under the curve (AUC)-retinyl ester (RE) HME, 844 ± 127 vs. controls, 646 ± 119 nM/h, P = 0.09]. Moreover, in FH subjects with a high HSPG gene score, retinyl palmitate excursions were higher (AUC-RE, 2,377 ± 293 vs. 1,565 ± 181 nM/h, P < 0.05). Incremental AUC-apoB48 was similar between the groups. In conclusion, the data are supportive for a minor yet additive role of HSPG in human postprandial TG clearance, and further studies are warranted.

The contribution of intestinal bacterial strains (gut microbiota) in the development of cardiometabolic disease is increasingly recognized as potential diagnostic and pharmacological target. Changes in the intestinal bacterial composition and subsequent altered diversity has been associated with presence of chronic low-grade inflammation of mesenteric visceral adipose tissue, a known feature of malign obesity which can eventually lead to insulin resistance and type 2 diabetes mellitus. However, causality still needs to be proven. In this regard, both fecal transplantation studies as well as multiethnic prospective cohorts can help to identify the causally involved driving intestinal bacterial strains in human cardiometabolism. Ultimately, it is expected that novel diagnostic markers as well as therapeutics (pharmabiotics and vaccine strategies) can be developed.

Exotosin (EXT) proteins are involved in the chain elongation step of heparan sulfate (HS) biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF) in EXT1 and EXT2 result in hereditary exostoses (HME). Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME) affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT) followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS) in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI). OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46-1.16] vs. controls 1.53 [0.69-3.36] nmol.l(-1).min(-1), p<0.05). Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22-10.5] vs. controls 10.2 [7.91-12.70] nmol.l(-1).min(-1) p<0.05), indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0 +/- 15.8 vs. controls 96.5 +/- 26.0 cm(3) p=0.04). In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors.

The isocitrate dehydrogenase 1 (IDH1) mutation occurs in high frequency in glioma and secondary glioblastoma (GBM). Mutated IDH1 produces the oncometabolite 2-hydroxyglutarate rather than α-ketoglutarate or isocitrate. The oncometabolite is considered to be the major cause of the association between the IDH1 mutation and gliomagenesis. On the other hand, the IDH1 mutation in GBM is associated with prolonged patient survival. This association is not well understood yet but IDH1 involvement in epigenetic silencing of O-6-methylguanine-DNA methyltransferase (MGMT), a DNA repair enzyme is considered to be an important mechanism. However, it was shown recently that the IDH1 mutation and MGMT silencing are independent prognostic factors. Here, we hypothesize that the IDH1 mutation reduces the capacity to produce NADPH and thus reduces the capacity to scavenge reactive oxygen species that are generated during irradiation and chemotherapy. IDH1 activity is responsible for two-thirds of the NADPH production capacity in normal brain, whereas the IDH1 mutation reduces this capacity by almost 40%. Therefore, we hypothesize that the reduced NADPH production capacity due to the IDH1 mutation renders GBM cells more vulnerable to irradiation and chemotherapy thus prolonging survival of the patients.

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice.