Atherosclerotic cardiovascular disease is the leading cause of mortality worldwide, and hypercholesterolemia is a central risk factor for atherosclerosis. This study evaluated the effects of Totum... Show moreAtherosclerotic cardiovascular disease is the leading cause of mortality worldwide, and hypercholesterolemia is a central risk factor for atherosclerosis. This study evaluated the effects of Totum-070, a plant-based polyphenol-rich supplement, in hamsters with high-fat diet (HFD)-induced dyslipidemia. The molecular mechanisms of action were explored using human Caco2 enterocytes. Totum-070 supplementation reduced the total cholesterol (-41%), non-HDL cholesterol (-47%), and triglycerides (-46%) in a dose-dependent manner, compared with HFD. HFD-induced hepatic steatosis was also significantly decreased by Totum-070, an effect associated with the reduction in various lipid and inflammatory gene expression. Upon challenging with olive oil gavage, the post-prandial triglyceride levels were strongly reduced. The sterol excretion in the feces was increased in the HFD-Totum-070 groups compared with the HFD group and associated with reduction of intestinal cholesterol absorption. These effects were confirmed in the Caco2 cells, where incubation with Totum-070 inhibited cholesterol uptake and apolipoprotein B secretion. Furthermore, a microbiota composition analysis revealed a strong effect of Totum-070 on the alpha and beta diversity of bacterial species and a significant decrease in the Firmicutes to Bacteroidetes ratio. Altogether, our findings indicate that Totum-070 lowers hypercholesterolemia by reducing intestinal cholesterol absorption, suggesting that its use as dietary supplement may be explored as a new preventive strategy for cardiovascular diseases. Show less
PiZZ (Glu342Lys) alpha 1-antitrypsin deficiency (AATD) is characterized by intrahepatic AAT polymerization and is a risk factor for liver disease development in children. The majority of PiZZ... Show morePiZZ (Glu342Lys) alpha 1-antitrypsin deficiency (AATD) is characterized by intrahepatic AAT polymerization and is a risk factor for liver disease development in children. The majority of PiZZ children are disease free, hence this mutation alone is not sufficient to cause the disease. We investigated Z-AAT polymers and the expression of fibrosis-related genes in liver tissues of PiZZ children with different clinical courses. Liver biopsies obtained during 1979-2010 at the Department of Paediatrics, Karolinska University Hospital, Sweden, were subjected to histological re-evaluation, immunohistochemistry and NanoString-based transcriptome profiling using a panel of 760 fibrosis plus 8 bile acid-related genes. Subjects were divided into three groups based on clinical outcomes: NCH (neonatal cholestasis, favourable outcome, n = 5), NCC (neonatal cholestasis, early cirrhosis and liver transplantation, n = 4), and NNCH (no neonatal cholestasis, favourable outcome, n = 5, six biopsies). Hepatocytes containing Z-AAT polymers were abundant in all groups whereas NCC showed higher expression of genes related to liver fibrosis/cirrhosis and lower expression of genes related to lipid, aldehyde/ketone, and bile acid metabolism. Z-AAT accumulation per se cannot explain the clinical outcomes of PiZZ children; however, changes in the expression of specific genes and pathways involved in lipid, fatty acid, and steroid metabolism appear to reflect the degree of liver injury. Show less
PiZZ (Glu342Lys) α1-antitrypsin deficiency (AATD) is characterized by intrahepatic AAT polymerization and is a risk factor for liver disease development in children. The majority of PiZZ children... Show morePiZZ (Glu342Lys) α1-antitrypsin deficiency (AATD) is characterized by intrahepatic AAT polymerization and is a risk factor for liver disease development in children. The majority of PiZZ children are disease free, hence this mutation alone is not sufficient to cause the disease. We investigated Z-AAT polymers and the expression of fibrosis-related genes in liver tissues of PiZZ children with different clinical courses. Liver biopsies obtained during 1979–2010 at the Department of Paediatrics, Karolinska University Hospital, Sweden, were subjected to histological re-evaluation, immunohistochemistry and NanoString-based transcriptome profiling using a panel of 760 fibrosis plus 8 bile acid-related genes. Subjects were divided into three groups based on clinical outcomes: NCH (neonatal cholestasis, favourable outcome, n = 5), NCC (neonatal cholestasis, early cirrhosis and liver transplantation, n = 4), and NNCH (no neonatal cholestasis, favourable outcome, n = 5, six biopsies). Hepatocytes containing Z-AAT polymers were abundant in all groups whereas NCC showed higher expression of genes related to liver fibrosis/cirrhosis and lower expression of genes related to lipid, aldehyde/ketone, and bile acid metabolism. Z-AAT accumulation per se cannot explain the clinical outcomes of PiZZ children; however, changes in the expression of specific genes and pathways involved in lipid, fatty acid, and steroid metabolism appear to reflect the degree of liver injury. Show less
Vos, D.Y.; Wijers, M.; Smit, M.; Huijkman, N.; Kloosterhuis, N.J.; Wolters, J.C.; ... ; Sluis, B. van de 2023
Background:The copper metabolism MURR1 domains/coiled-coil domain containing 22/coiled-coil domain containing 93 (CCC) complex is required for the transport of low-density lipoprotein receptor ... Show moreBackground:The copper metabolism MURR1 domains/coiled-coil domain containing 22/coiled-coil domain containing 93 (CCC) complex is required for the transport of low-density lipoprotein receptor (LDLR) and LRP1 (LDLR-related protein 1) from endosomes to the cell surface of hepatocytes. Impaired functioning of hepatocytic CCC causes hypercholesterolemia in mice, dogs, and humans. Retriever, a protein complex consisting of subunits VPS26C, VPS35L, and VPS29, is associated with CCC, but its role in endosomal lipoprotein receptor transport is unclear. We here investigated the contribution of retriever to hepatocytic lipoprotein receptor recycling and plasma lipids regulation. Methods:Using somatic CRISPR/Cas9 gene editing, we generated liver-specific VPS35L or VPS26C-deficient mice. We determined total and surface levels of LDLR and LRP1 and plasma lipids. In addition, we studied the protein levels and composition of CCC and retriever. Results: Hepatocyte VPS35L deficiency reduced VPS26C levels but had minimal impact on CCC composition. VPS35L deletion decreased hepatocytic surface expression of LDLR and LRP1, accompanied by a 21% increase in plasma cholesterol levels. Hepatic VPS26C ablation affected neither levels of VPS35L and CCC subunits, nor plasma lipid concentrations. However, VPS26C deficiency increased hepatic LDLR protein levels by 2-fold, probably compensating for reduced LRP1 functioning, as we showed in VPS26C-deficient hepatoma cells. Upon PCSK9 (proprotein convertase subtilisin/kexin type 9)-mediated LDLR elimination, VPS26C ablation delayed postprandial triglyceride clearance and increased plasma triglyceride levels by 26%. Conclusions: Our study suggests that VPS35L is shared between retriever and CCC to facilitate LDLR and LRP1 transport from endosomes to the cell surface. Conversely, retriever subunit VPS26C selectively transports LRP1, but not LDLR, and thereby may control hepatic uptake of postprandial triglyceride-rich lipoprotein remnants. Show less
Buurstede, J.C.; Paul, S.N.; Bosscher, K. de; Meijer, O.C.; Kroon, J. 2022
Glucocorticoids exert their pleiotropic effects by activating the glucocorticoid receptor (GR), which is expressed throughout the body. GR-mediated transcription is regulated by a multitude of... Show moreGlucocorticoids exert their pleiotropic effects by activating the glucocorticoid receptor (GR), which is expressed throughout the body. GR-mediated transcription is regulated by a multitude of tissue- and cell type-specific mechanisms, including interactions with other transcription factors such as the androgen receptor (AR). We previously showed that the transcription of canonical glucocorticoid-responsive genes is dependent on active androgen signaling, but the extent of this glucocorticoid-androgen crosstalk warrants further investigation. In this study, we investigated the overall glucocorticoid-androgen crosstalk in the hepatic transcriptome. Male mice were exposed to GR agonist corticosterone and AR antagonist enzalutamide in order to determine the extent of androgen-dependency after acute and chronic exposure. We found that a substantial proportion of the hepatic transcriptome is androgen-dependent after chronic exposure, while after acute exposure the transcriptomic effects of glucocorticoids are largely androgen-independent. We propose that prolonged glucocorticoid exposure triggers a gradual upregulation of AR expression, instating a situation of androgen dependence which is likely not driven by direct AR-GR interactions. This indirect mode of glucocorticoid-androgen interaction is in accordance with the absence of enriched AR DNA-binding near AR-dependent corticosterone-regulated genes after chronic exposure. In conclusion, we demonstrate that glucocorticoid effects and their interaction with androgen signaling are dependent on the duration of exposure and believe that our findings contribute to a better understanding of hepatic glucocorticoid biology in health and disease. Show less
Background Feed efficiency (FE) is an important trait for livestock and humans. While the livestock industry focuses on increasing FE, in the current obesogenic society it is more of interest to... Show moreBackground Feed efficiency (FE) is an important trait for livestock and humans. While the livestock industry focuses on increasing FE, in the current obesogenic society it is more of interest to decrease FE. Hence, understanding mechanisms involved in the regulation of FE and particularly how it can be decreased would help tremendously in counteracting the obesity pandemic. However, it is difficult to accurately measure or calculate FE in humans. In this study, we aimed to address this challenge by developing a hierarchical dynamic model based on humanized mouse data.Methods We analyzed existing experimental data derived from 105 APOE*3-Leiden.CETP (E3L.CETP) mice fed a high-fat high-cholesterol (HFHC) diet for 1 (N = 20), 2 (N = 19), 3 (N = 20), and 6 (N = 46) month. We developed an ordinary differential equation (ODE) based model to estimate the FE based on the longitudinal data of body weight and food intake. Since the liver plays an important role in maintaining metabolic homeostasis, we evaluated associations between FE and hepatic gene expression levels. Depending on the feeding duration, we observed different relationships between FE and hepatic gene expression levels.Results After 1-month feeding of HFHC diet, we observed that FE was associated with vitamin A metabolism, arachidonic acid metabolism, and the PPAR signaling pathway. After 3- and 6-month feeding of HFHC diet, we observed that FE was associated most strongly with expression levels of Spink1 and H19, genes involved in cell proliferation and glucose metabolism, respectively.Conclusions In conclusion, our analysis suggests that various biological processes such as vitamin A metabolism, hepatic response to inflammation, and cell proliferation associate with FE at different stages of diet-induced obesity. Show less
Morelli, V.M.; Mutsert, R. de; Roos, A. de; Lamb, H.J.; Vlieg, A.V.; Bos, M.H.A.; ... ; Cannegieter, S.C. 2020
Objective:Whether hepatic triglyceride content (HTGC) contributes to hypercoagulability beyond total body fat (TBF) and visceral adipose tissue (VAT) is unclear. We, therefore, aimed to investigate... Show moreObjective:Whether hepatic triglyceride content (HTGC) contributes to hypercoagulability beyond total body fat (TBF) and visceral adipose tissue (VAT) is unclear. We, therefore, aimed to investigate the association between HTGC and coagulation factors (F)I (fibrinogen), VIII, IX, and XI while adjusting for TBF and VAT.Approach and Results:In this cross-sectional analysis of the NEO study (Netherlands Epidemiology of Obesity; n=6671), a random subset of participants underwent magnetic resonance imaging and magnetic resonance spectroscopy to assess VAT and HTGC (n=2580). We excluded participants without complete imaging and coagulation assessment, and with history of liver disease, venous thrombosis, or on anticoagulation. Mean differences in coagulation factor levels across HTGC quartiles were estimated by linear regression adjusted for age, sex, ethnicity, education, alcohol intake, physical activity, smoking, estrogen, and menopause, in addition to TBF and VAT. Among the 1946 participants included, median HTGC was 2.66% (interquartile range: 1.34%-6.27%). Coagulation factor levels increased dose-dependently across HTGC quartiles. Mean differences between the fourth and first quartiles were 14.7 mg/dL (95% CI, 2.1-27.2) for fibrinogen, 6.7 IU/dL (95% CI, 0.5-12.9) for FVIII, 26.1 IU/dL (95% CI, 22.4-29.8) for FIX, and 8.6 IU/dL (95% CI, 4.6-12.6) for FXI. With further adjustment for TBF and VAT, the dose-response association of HTGC with FIX persisted, whereas associations with other factors disappeared.Conclusions:HTGC was associated with various coagulation factors, of which FIX remained associated with HTGC after adjustment for TBF and VAT. HTGC might contribute to venous thrombosis risk beyond total body and visceral fat through FIX levels. Show less
Invariant natural killer T cells (iNKT) constitute up to 50% of liver lymphocytes and contribute to immunosurveillance as well as pathogenesis of the liver. Systemic activation of iNKT cells... Show moreInvariant natural killer T cells (iNKT) constitute up to 50% of liver lymphocytes and contribute to immunosurveillance as well as pathogenesis of the liver. Systemic activation of iNKT cells induces acute immune-mediated liver injury. However, how tissue damage events regulate iNKT cell function and homeostasis remains unclear. We found that specifically tissue-resident iNKT cells in liver and spleen express the tissue-damage receptor P2RX7 and the P2RX7-activating ectoenzyme ARTC2. P2RX7 expression restricted formation of iNKT cells in the liver suggesting that liver iNKT cells are actively restrained under homeostatic conditions. Deliberate activation of P2RX7 in vivo by exogenous NAD resulted in a nearly complete iNKT cell ablation in liver and spleen in a P2RX7-dependent manner. Tissue damage generated by acetaminophen-induced liver injury reduced the number of iNKT cells in the liver. The tissue-damage-induced iNKT cell depletion was driven by P2RX7 and localized to the site of injury, as iNKT cells in the spleen remained intact. The depleted liver iNKT cells reconstituted only slowly compared to other lymphocytes such as regulatory T cells. These findings suggest that tissue-damage-mediated depletion of iNKT cells acts as a feedback mechanism to limit iNKT cell-induced pathology resulting in the establishment of a tolerogenic environment. Show less
Huet, C.; Boudaba, N.; Guigas, B.; Viollet, B.; Foretz, M. 2020
The cellular energy sensor AMP-activated protein kinase (AMPK) is a metabolic regulator that mediates adaptation to nutritional variations to maintain a proper energy balance in cells. We show here... Show moreThe cellular energy sensor AMP-activated protein kinase (AMPK) is a metabolic regulator that mediates adaptation to nutritional variations to maintain a proper energy balance in cells. We show here that suckling-weaning and fasting-refeeding transitions in rodents are associated with changes in AMPK activation and the cellular energy state in the liver. These nutritional transitions were characterized by a metabolic switch from lipid to glucose utilization, orchestrated by modifications in glucose levels and the glucagon/insulin ratio in the bloodstream. We therefore investigated the respective roles of glucose and pancreatic hormones on AMPK activation in mouse primary hepatocytes. We found that glucose starvation transiently activates AMPK, whereas changes in glucagon and insulin levels had no impact on AMPK. Challenge of hepatocytes with metformin-induced metabolic stress strengthened both AMPK activation and cellular energy depletion under limited-glucose conditions, whereas neither glucagon nor insulin altered AMPK activation. Although both insulin and glucagon induced AMPK? phosphorylation at its Ser(485/491) residue, they did not affect its activity. Finally, the decrease in cellular ATP levels in response to an energy stress was additionally exacerbated under fasting conditions and by AMPK deficiency in hepatocytes, revealing metabolic inflexibility and emphasizing the importance of AMPK for maintaining hepatic energy charge. Our results suggest that nutritional changes (i.e. glucose availability), rather than the related hormonal changes (i.e. the glucagon/insulin ratio), sensitize AMPK activation to the energetic stress induced by the dietary transition during fasting. This effect is critical for preserving the cellular energy state in the liver. Show less
Helm, D. van der; Barnhoorn, M.C.; Jonge-Muller, E.S.M. de; Molendijk, I.; Hawinkels, L.J.A.C.; Coenraad, M.J.; ... ; Verspaget, H.W. 2019
