Pancreatic beta-cell failure is a critical event in the onset of both main types of diabetes mellitus but underlying mechanisms are not fully understood. beta-cells have low anti-oxidant capacity,... Show morePancreatic beta-cell failure is a critical event in the onset of both main types of diabetes mellitus but underlying mechanisms are not fully understood. beta-cells have low anti-oxidant capacity, making them more susceptible to oxidative stress. In type 1 diabetes (T1D), reactive oxygen species (ROS) are associated with pro-inflammatory conditions at the onset of the disease. Here, we investigated the effects of hydrogen peroxide-induced oxidative stress on human beta-cells. We show that primary human beta-cell function is decreased. This reduced function is associated with an ER stress response and the shuttling of FOXO1 to the nucleus. Furthermore, oxidative stress leads to loss of beta-cell maturity genes MAFA and PDX1, and to a concomitant increase in progenitor marker expression of SOX9 and HES1. Overall, we propose that oxidative stress-induced beta-cell failure may result from partial dedifferentiation. Targeting antioxidant mechanisms may preserve functional beta-cell mass in early stages of development of T1D. Show less
Background. Previous clinical studies have shown that various measures of glucose metabolism are associated with a risk of chronic kidney disease in different populations, but results were not... Show moreBackground. Previous clinical studies have shown that various measures of glucose metabolism are associated with a risk of chronic kidney disease in different populations, but results were not consistent. In this study we assessed measures of glucose metabolism and their association with kidney function in a population-based study.Methods. The Netherlands Epidemiology of Obesity study is a population-based cohort study of middle-aged men and women. We categorized the study population according to glycaemic levels into normoglycaemia (reference group), pre-diabetes mellitus (pre-DM), known DM and newly diagnosed DM. Outcome variables were serum creatinine, estimated glomerular filtration rate (eGFR), glomerular hyperfiltration (defined as an eGFR >90th percentile; >102mL/min/1.73m(2)) and micro-albuminuria. We examined the association between measures of glucose metabolism [fasting glucose, haemoglobin A1c (HbA1c), fasting insulin, glucose area under the curve (AUC), insulin AUC, Homoeostatic Model Assessment of Insulin Resistance (HOMA-IR), HOMA of beta-cell function (HOMA-B) and disposition index] and measures of kidney function.Results. Of the total population (N=6338), 55% of participants were classified as normoglycaemic (reference), 35% as pre-DM, 7% as DM and 4% as newly diagnosed DM. Compared with the reference group, diagnosed and newly diagnosed DMs were associated with a slightly higher trend in eGFR {+2.1mL/min/1.73m(2) [95% confidence interval (CI) -0.2-4.4] and +2.7mL/min/1.73m(2) [95% CI -0.3-5.7], respectively}. A 1% higher HbA1c was associated with increased odds of hyperfiltration [odds ratio (OR) 1.41 (95% CI 1.06-1.88)]. Higher levels of fasting plasma glucose, AUC glucose and HOMA-B were associated with hyperfiltration. Fasting insulin, AUC insulin and HOMA-IR were not associated with hyperfiltration. The OR of microalbuminuria was 1.21 (95% CI 1.04-1.42) per mmol/L higher fasting glucose concentrations.Conclusions. Both fasting and post-prandial glucose and HOMA-B, but not measures of insulin resistance, were associated with glomerular hyperfiltration, while fasting glucose was also associated with microalbuminuria. Show less
Balak, J.R.A.; Graaf, N. de; Zaldumbide, A.; Rabelink, T.J.; Hoeben, R.C.; Koning, E.J.P. de; Carlotti, F. 2019
The lack of efficient gene transfer methods into primary human pancreatic exocrine cells hampers studies on the plasticity of these cells and their possible role in beta cell regeneration.... Show moreThe lack of efficient gene transfer methods into primary human pancreatic exocrine cells hampers studies on the plasticity of these cells and their possible role in beta cell regeneration. Therefore, improved gene transfer protocols are needed. Lentiviral vectors are widely used to drive ectopic gene expression in mammalian cells, including primary human islet cells. Here we aimed to optimize gene transfer into primary human exocrine cells using modified lentiviral vectors or transduction conditions. We evaluated different promoters, viral envelopes, medium composition and transduction adjuvants. Transduction efficiency of a reporter vector was evaluated by fluorescence microscopy and flow cytometry. We show that protamine sulfate-assisted transduction of a VSV-G-pseudotyped vector expressing eGFP under the control of a CMV promoter in a serum-free environment resulted in the best transduction efficiency of exocrine cells, reaching up to 90% of GFP-positive cells 5 days after transduction. Our findings will enable further studies on pancreas (patho)physiology that require gene transfer such as gene overexpression, gene knockdown or lineage tracing studies. Show less
Berg, B.M. van den; Wang, G.Q.; Boels, M.G.S.; Avramut, M.C.; Jansen, E.; Sol, W.M.P.J.; ... ; Rabelink, T.J. 2019
Background A glycocalyx envelope consisting of proteoglycans and adhering proteins covers endothelial cells, both the luminal and abluminal surface. We previously demonstrated that short-term loss... Show moreBackground A glycocalyx envelope consisting of proteoglycans and adhering proteins covers endothelial cells, both the luminal and abluminal surface. We previously demonstrated that short-term loss of integrity of the luminal glycocalyx layer resulted in perturbed glomerular filtration barrier function.Methods To explore the role of the glycocalyx layer of the endothelial extracellular matrix in renal function, we generated mice with an endothelium-specific and inducible deletion of hyaluronan synthase 2 (Has2), the enzyme that produces hyaluronan, the main structural component of the endothelial glycocalyx layer. We also investigated the presence of endothelial hyaluronan in human kidney tissue from patients with varying degrees of diabetic nephropathy.Results Endothelial deletion of Has2 in adult mice led to substantial loss of the glycocalyx structure, and analysis of their kidneys and kidney function showed vascular destabilization, characterized by mesangiolysis, capillary ballooning, and albuminuria. This process develops over time into glomerular capillary rarefaction and glomerulosclerosis, recapitulating the phenotype of progressive human diabetic nephropathy. Using a hyaluronan-specific probe, we found loss of glomerular endothelial hyaluronan in association with lesion formation in tissue from patients with diabetic nephropathy. We also demonstrated that loss of hyaluronan, which harbors a specific binding site for angiopoietin and a key regulator of endothelial quiescence and maintenance of EC barrier function results in disturbed angiopoietin 1 Tie2.Conclusions Endothelial loss of hyaluronan results in disturbed glomerular endothelial stabilization. Glomerular endothelial hyaluronan is a previously unrecognized key component of the extracelluar matrixthat is required for glomerular structure and function and lost in diabetic nephropathy. Show less
Nijhoff, M.F.; Dubbeld, J.; Erkel, A.R. van; Boog, P.J.M. van der; Rabelink, T.J.; Engelse, M.A.; Koning, E.J.P. de 2018
High-fat, low-carbohydrate ketogenic diets (KD) are used for weight loss and for treatment of refractory epilepsy. Recently, short-time studies in rodents have shown that, besides their beneficial... Show moreHigh-fat, low-carbohydrate ketogenic diets (KD) are used for weight loss and for treatment of refractory epilepsy. Recently, short-time studies in rodents have shown that, besides their beneficial effect on body weight, KD lead to glucose intolerance and insulin resistance. However, the long-term effects on pancreatic endocrine cells are unknown. In this study we investigate the effects of long-term KD on glucose tolerance and β- and α-cell mass in mice. Despite an initial weight loss, KD did not result in weight loss after 22 wk. Plasma markers associated with dyslipidemia and inflammation (cholesterol, triglycerides, leptin, monocyte chemotactic protein-1, IL-1β, and IL-6) were increased, and KD-fed mice showed signs of hepatic steatosis after 22 wk of diet. Long-term KD resulted in glucose intolerance that was associated with insufficient insulin secretion from β-cells. After 22 wk, insulin-stimulated glucose uptake was reduced. A reduction in β-cell mass was observed in KD-fed mice together with an increased number of smaller islets. Also α-cell mass was markedly decreased, resulting in a lower α- to β-cell ratio. Our data show that long-term KD causes dyslipidemia, a proinflammatory state, signs of hepatic steatosis, glucose intolerance, and a reduction in β- and α-cell mass, but no weight loss. This indicates that long-term high-fat, low-carbohydrate KD lead to features that are also associated with the metabolic syndrome and an increased risk for type 2 diabetes in humans. Show less
Ellenbroek, J.H.; Tons, H.A.M.; Meeteren, M.J.A.W. van; Graaf, N. de; Hanegraaf, M.A.; Rabelink, T.J.; ... ; Koning, E.J.P. de 2013
Objective-To compare the effects of rosiglitazone (8 mg/d, n = 19) and metformin (2 g/d, n = 18) on postprandial lipemia in patients with HIV-lipodystrophy. Methods and Results-Lipodystrophy in HIV... Show moreObjective-To compare the effects of rosiglitazone (8 mg/d, n = 19) and metformin (2 g/d, n = 18) on postprandial lipemia in patients with HIV-lipodystrophy. Methods and Results-Lipodystrophy in HIV is associated with insulin resistance and disturbed postprandial triglyceride and free fatty acid (FFA) metabolism. We conducted an open randomized 6-month study with standardized 10-h oral fat-loading tests at baseline and after treatment. Rosiglitazone (-34%) and metformin (-37%) reduced homeostasis model assessment similarly (P < 0.05). Rosiglitazone did not change the area under the curve for FFA and triglyceride; however, it did reduce the area under the curve for hydroxybutyric acid (a marker of hepatic FFA oxidation) by 25% (P < 0.05). Rosiglitazone increased the area under the curve for remnantlike particle cholesterol by 40% (P < 0.01) compared with baseline. Metformin did not change any of the postprandial measurements. Conclusion-Rosiglitazone improved insulin sensitivity and decreased postprandial hydroxybutyric acid levels in patients with HIV-lipodystrophy, suggesting improved FFA handling. Despite metabolic improvements, rosiglitazone caused a marked increase in postprandial remnantlike particle cholesterol, which may adversely affect cardiovascular risk. Metformin did not affect postprandial lipemia and could be used to treat insulin resistance in this population. (Arterioscler Thromb Vasc Biol. 2011;31:228-233.) Show less
