Global prevalence of obesity and type 2 diabetes are rapidly increasing to pandemic proportions. A novel supplement composed of 5 plant extracts from olive leaf, bilberry, artichoke,... Show moreGlobal prevalence of obesity and type 2 diabetes are rapidly increasing to pandemic proportions. A novel supplement composed of 5 plant extracts from olive leaf, bilberry, artichoke, chrysanthellum, and black pepper was designed to prevent type 2 diabetes development in people at risk. It was previously shown to improve body weight and glucose control in preclinical rodent models, with these effects being accompanied by increased fecal energy excretion and in vitro inhibition of several digestive enzymes. Thus, we hypothesized that, in mice fed a high-fat diet (HFD), a single dose of this botanical supplementation would decrease the responses to oral fat and carbohydrate tolerance tests, and that chronic supplementation would result in increased fecal triglyceride content. We showed that acute administration in HFD-fed mice (1.452 g/kg body weight) markedly reduced circulating triglycerides following an oral lipid gavage, whereas glycemic responses to various carbohydrate tests were only mildly affected. When incorporated into the food (2.5%) of HFD-fed mice, chronic supplementation prevented body weight gain and improved glucose homeostasis and lipid tolerance. Fecal free fatty acid content, but not triglyceride, was significantly increased in supplemented animals, suggesting reduced lipid absorption in the digestive tract. Congruently, this botanical supplementation downregulated several genes associated with fatty acid transport whose expression was increased by HFD, principally in the jejunum. This study provides novel insights as for the mode of action behind the antiobesity effect of this plant-based supplementation, in HFD-fed mice. Show less
Glucagon-like peptide-1 (GLP-1) receptor agonists are a relatively new treatment option for obesity and type 2 diabetes. Treatment has been shown to result in in weight loss and improved glycemic... Show moreGlucagon-like peptide-1 (GLP-1) receptor agonists are a relatively new treatment option for obesity and type 2 diabetes. Treatment has been shown to result in in weight loss and improved glycemic control. In this thesis, the effects of treatment on the different adipose tissue depots and on cardiac function are described. In a randomised controlled trial, we treated patients with type 2 diabetes from South Asian descent, a population with increased risk to develop type 2 diabetes and cardiovascular disease compared to Western Europeans, with liraglutide, a GLP-1 receptor agonist, or placebo, and studied these subjects with MRI. We concluded that liraglutide and possibly other GLP-1 receptor agonists can be a good strategy to reduce the volume of visceral adipose tissue. This reduction was accompanied by a significant improvement of glycemic control. Lastly, we provided evidence that liraglutide does not improve cardiac function and myocardial tissue characteristics and thus does not improve diabetic cardiomyopathy. In addition, in another study, we studied the mechanism behind GLP-1 receptor agonism induced weight loss and concluded that liraglutide induces weight loss in humans by decreasing energy intake rather than by activating brown adipose tissue or increasing energy expenditure. Show less
Aims/hypothesisThe aim of this study was to identify differentially expressed long non-coding RNAs (lncRNAs) and mRNAs in whole blood of people with type 2 diabetes across five different clusters:... Show moreAims/hypothesisThe aim of this study was to identify differentially expressed long non-coding RNAs (lncRNAs) and mRNAs in whole blood of people with type 2 diabetes across five different clusters: severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), mild obesity-related diabetes (MOD), mild diabetes (MD) and mild diabetes with high HDL-cholesterol (MDH). This was to increase our understanding of different molecular mechanisms underlying the five putative clusters of type 2 diabetes.MethodsParticipants in the Hoorn Diabetes Care System (DCS) cohort were clustered based on age, BMI, HbA1c, C-peptide and HDL-cholesterol. Whole blood RNA-seq was used to identify differentially expressed lncRNAs and mRNAs in a cluster compared with all others. Differentially expressed genes were validated in the Innovative Medicines Initiative DIabetes REsearCh on patient straTification (IMI DIRECT) study. Expression quantitative trait loci (eQTLs) for differentially expressed RNAs were obtained from a publicly available dataset. To estimate the causal effects of RNAs on traits, a two-sample Mendelian randomisation analysis was performed using public genome-wide association study (GWAS) data.ResultsEleven lncRNAs and 175 mRNAs were differentially expressed in the MOD cluster, the lncRNA AL354696.2 was upregulated in the SIDD cluster and GPR15 mRNA was downregulated in the MDH cluster. mRNAs and lncRNAs that were differentially expressed in the MOD cluster were correlated among each other. Six lncRNAs and 120 mRNAs validated in the IMI DIRECT study. Using two-sample Mendelian randomisation, we found 52 mRNAs to have a causal effect on anthropometric traits (n=23) and lipid metabolism traits (n=10). GPR146 showed a causal effect on plasma HDL-cholesterol levels (p = 2×10–15), without evidence for reverse causality.Conclusions/interpretationMultiple lncRNAs and mRNAs were found to be differentially expressed among clusters and particularly in the MOD cluster. mRNAs in the MOD cluster showed a possible causal effect on anthropometric traits, lipid metabolism traits and blood cell fractions. Together, our results show that individuals in the MOD cluster show aberrant RNA expression of genes that have a suggested causal role on multiple diabetes-relevant traits. Show less
Aims/hypothesisAnimal studies have indicated that disturbed diurnal rhythms of clock gene expression in adipose tissue can induce obesity and type 2 diabetes. The importance of the circadian timing... Show moreAims/hypothesisAnimal studies have indicated that disturbed diurnal rhythms of clock gene expression in adipose tissue can induce obesity and type 2 diabetes. The importance of the circadian timing system for energy metabolism is well established, but little is known about the diurnal regulation of (clock) gene expression in obese individuals with type 2 diabetes. In this study we aimed to identify key disturbances in the diurnal rhythms of the white adipose tissue transcriptome in obese individuals with type 2 diabetes.MethodsIn a case-control design, we included six obese individuals with type 2 diabetes and six healthy, lean control individuals. All participants were provided with three identical meals per day for 3days at zeitgeber time (ZT, with ZT 0:00 representing the time of lights on) 0:30, 6:00 and 11:30. Four sequential subcutaneous abdominal adipose tissue samples were obtained, on day 2 at ZT 15:30, and on day 3 at ZT 0:15, ZT 5:45 and ZT 11:15. Gene expression was measured using RNA sequencing.ResultsThe core clock genes showed reduced amplitude oscillations in the individuals with type 2 diabetes compared with the healthy control individuals. Moreover, in individuals with type 2 diabetes, only 1.8% (303 genes) of 16,818 expressed genes showed significant diurnal rhythmicity, compared with 8.4% (1421 genes) in healthy control individuals. Enrichment analysis revealed a loss of rhythm in individuals with type 2 diabetes of canonical metabolic pathways involved in the regulation of lipolysis. Enrichment analysis of genes with an altered mesor in individuals with type 2 diabetes showed decreased activity of the translation initiating pathway EIF2 signaling'. Individuals with type 2 diabetes showed a reduced diurnal rhythm in postprandial glucose concentrations.Conclusions/interpretationDiurnal clock and metabolic gene expression rhythms are decreased in subcutaneous adipose tissue of obese individuals with type 2 diabetes compared with lean control participants. Future investigation is needed to explore potential treatment targets as identified by our study, including clock enhancement and induction of EIF2 signalling.Data availabilityThe raw sequencing data and supplementary files for rhythmic expression analysis and Ingenuity Pathway Analysis have been deposited in NCBI Gene Expression Omnibus (GEO series accession number GSE104674). Show less
Cardiovascular disease is the number one cause of death worldwide. The most important risk factor for developing this disease is high cholesterol levels in the blood. Other risk factors... Show moreCardiovascular disease is the number one cause of death worldwide. The most important risk factor for developing this disease is high cholesterol levels in the blood. Other risk factors contributing to cardiovascular disease can develop in individuals which are overweight. The clinical consequences of being overweight are clustered in the medical term: metabolic syndrome. Included in the metabolic syndrome are high blood pressure, dyslipidemia and glucose intolerance. At present, most cardiovascular disease patients are treated with statins which lower blood cholesterol levels. However, this treatment is not as effective in all patients and can cause some adverse drug reactions. Therefore, it is essential that novel therapeutic targets for the treatment of cardiovascular disease are identified. In this thesis, potential novel therapeutic targets in cardiovascular disease and metabolic syndrome are validated. In total, three potential targets were investigated: proteoglycan 4, protein arginine methyltransferase 3 and stabilin 1. Our studies showed the involvement of two of these targets in the development of cardiovascular disease and metabolic syndrome. Moreover, our results stress (1) that cardiovascular disease and metabolic syndrome are complex, multifactorial diseases with overlapping mechanisms and (2) that integration of research into both diseases can benefit therapeutic target identification and validation. Show less
Conclusions/interpretation This study shows that type 2 diabetes is characterised by increased fasting and postprandial plasma alpha-dicarbonyl stress, which can be reduced by improving glucose... Show moreConclusions/interpretation This study shows that type 2 diabetes is characterised by increased fasting and postprandial plasma alpha-dicarbonyl stress, which can be reduced by improving glucose metabolism through a VLCD or RYGB. These data highlight the potential to reduce reactive alpha-dicarbonyls in obese individuals with type 2 diabetes. Trial registration: ClinicalTrials.gov NCT01167959 Show less
