Objective: Inflammation plays an important role in all stages of atherosclerosis, but little is known about the therapeutic effects of quenching inflammation in already existing atherosclerotic... Show moreObjective: Inflammation plays an important role in all stages of atherosclerosis, but little is known about the therapeutic effects of quenching inflammation in already existing atherosclerotic lesions. Putative beneficial effects of salicylate, an inhibitor of NF-kappa B activation, were studied in mice with established lesions. Methods: ApoE*3-Leiden mice received a high-cholesterol diet (HC) to establish atherosclerotic lesions. Reference mice (REF) were sacrificed to determine the lesion area at the start of two interventions. In one intervention group HC diet feeding was continued, but the diet contained salicylate (HC + SAL). As salicylate not only quenches inflammation but also reduces plasma cholesterol, a second intervention group was fed a low-cholesterol diet (LC) resulting in cholesterol levels comparable to HC + SAL. The effects of these interventions on lesion area and composition were assessed after 8 and 16 weeks. Results: HC + SAL markedly reduced hepatic NF-kappa B activity compared to REF, and was significantly more effective than LC diet feeding. HC + SAL and LC also quenched aortic NF-kappa B activity. While continuing HC diet typically further increases total lesion area, 16 weeks of intervention with HC + SAL and LC halted further disease progression and resulted in lesion sizes comparable to that of REF. At the same time, lesion composition was significantly improved, particularly with salicylate. Strikingly, HC + SAL resulted in a lower lesional macrophage content and a greater plaque stability index (ratio of collagen to macrophage area) than LC. Conclusion: Anti-inflammatory salicylate reduces atherosclerotic macrophage content and increases lesion stability of pre-existing plaques through quenching of NF-kappa B activity and reducing plasma cholesterol. (C) 2010 Elsevier Ireland Ltd. All rights reserved. Show less
Stienstra, R.; Diepen, J.A. van; Tack, C.J.; Rensen, P.C.N.; Joosten, L.A.B.; Netea, M.G.; Kanneganti, T.D. 2010
The peroxisome proliferator-activated receptor alpha (PPAR alpha) activator fenofibrate efficiently decreases plasma triglycerides (TG), which is generally attributed to enhanced very low density... Show moreThe peroxisome proliferator-activated receptor alpha (PPAR alpha) activator fenofibrate efficiently decreases plasma triglycerides (TG), which is generally attributed to enhanced very low density lipoprotein (VLDL)-TG clearance and decreased VLDL-TG production. However, because data on the effect of fenofibrate on VLDL production are controversial, we aimed to investigate in (more) detail the mechanism underlying the TG-lowering effect by studying VLDL-TG production and clearance using APOE*3-Leiden.CETP mice, a unique mouse model for human-like lipoprotein metabolism. Male mice were fed a Western-type diet for 4 weeks, followed by the same diet without or with fenofibrate (30 mg/kg bodyweight/day) for 4 weeks. Fenofibrate strongly lowered plasma cholesterol (-38%) and TG (-60%) caused by reduction of VLDL. Fenofibrate markedly accelerated VLDL-TG clearance, as judged from a reduced plasma half-life of glycerol tri[H-3]oleate-labeled VLDL-like emulsion particles (-68%). This was associated with an increased post-heparin lipoprotein lipase (LPL) activity (+110%) and an increased uptake of VLDL-derived fatty acids by skeletal muscle, white adipose tissue, and liver. Concomitantly, fenofibrate markedly increased the VLDL-TG production rate (+73%) but not the VLDL-apolipoprotein B (apoB) production rate. Kinetic studies using [H-3] palmitic acid showed that fenofibrate increased VLDL-TG production by equally increasing incorporation of re-esterified plasma fatty acids and liver TG into VLDL, which was supported by hepatic gene expression profiling data. We conclude that fenofibrate decreases plasma TG by enhancing LPL-mediated VLDL-TG clearance, which results in a compensatory increase in VLDL-TG production by the liver. Show less
Timely sensing of lipopolysaccharide (LPS) is critical for the host to fight invading Gram-negative bacteria. We recently showed that apolipoprotein CI (apoCI) (apoCI(1-57)) avidly binds to LPS,... Show moreTimely sensing of lipopolysaccharide (LPS) is critical for the host to fight invading Gram-negative bacteria. We recently showed that apolipoprotein CI (apoCI) (apoCI(1-57)) avidly binds to LPS, involving an LPS-binding motif (apoCI(48-54)), and thereby enhances the LPS-induced inflammatory response. Our current aim was to further elucidate the structure and function relationship of apoCI with respect to its LPS-modulating characteristics and to unravel the mechanism by which apoCI enhances the biological activity of LPS. We designed and generated N- and C-terminal apoCI-derived peptides containing varying numbers of alternating cationic/hydrophobic motifs. ApoCI(1-38), apoCI(1-30), and apoCI(35-57) were able to bind LPS, whereas apoCI(1-23) and apoCI(46-57) did not bind LPS. In line with their LPS-binding characteristics, apoCI(1-38), apoCI(1-30), and apoCI(35-57) prolonged the serum residence of I-125-LPS by reducing its association with the liver. Accordingly, both apoCI(1-30) and apoCI(35-57) enhanced the LPS-induced TNF alpha response in vitro (RAW 264.7 macrophages) and in vivo (C57Bl/6 mice). Additional in vitro studies showed that the stimulating effect of apoCI on the LPS response resembles that of LPS-binding protein (LBP) and depends on CD14/ Toll-like receptor 4 signaling.(jlr) We conclude that apoCI contains structural elements in both its N-terminal and C-terminal helix to bind LPS and to enhance the proinflammatory response toward LPS via a mechanism similar to LBP.-Berbee, J. F. P., C. P. Coomans, M. Westerterp, J. A. Romijn, L. M. Havekes, and P. C. N. Rensen. Apolipoprotein CI enhances the biological response to LPS via the CD14/TLR4 pathway by LPS-binding elements in both its N- and C-terminal helix. J. Lipid Res. 2010. 51: 1943-1952 Show less
Jonker, J.T.; Wang, Y.N.; Haan, W. de; Diamant, M.; Rijzewijk, L.J.; Meer, R.W. van der; ... ; Smit, J.W.A. 2010
OBJECTIVE - Thiazolidinediones reduce hepatic steatosis and increase HDL cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic mice), a decrease in... Show moreOBJECTIVE - Thiazolidinediones reduce hepatic steatosis and increase HDL cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic mice), a decrease in hepatic triglyceride content is associated with a decrease in plasma cholesteryl ester transfer protein (CETP) mass and an increase in HDL levels. Therefore, the aim of the present study was to assess the effects of pioglitazone on CETP mass in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS - We included 78 men with type 2 diabetes (aged 56.5 +/- 0.6 years; HbA1c 7.1 +/- 0.1%) who were randomly assigned to treatment with pioglitazone (30 mg/day) or metformin (2000 mg/day) and matching placebo, in addition to glimepiride. At baseline and after 24 weeks of treatment plasma HDL cholesterol levels and CETP mass were measured, and hepatic triglyceride content was assessed by proton magnetic resonance spectroscopy. RESULTS - Pioglitazone decreased hepatic triglyceride content (5.9 [interquartile range 2.6-17.4] versus 4.1 [1.9-12.3]%, P < 0.05), decreased plasma CETP mass (2.33 +/- 0.10 vs. 2.06 +/- 0.10 mu g/ml, P < 0.05), and increased plasma HDL cholesterol level (1.22 +/- 0.05 vs. 1.34 +/- 0.05 mmol/l, P < 0.05). Metformin did not significantly change any of these parameters. CONCLUSIONS - A decrease in hepatic triglyceride content by pioglitazone is accompanied by a decrease in plasma CETP mass and associated with an increase in HDL cholesterol levels. These results in patients with type 2 diabetes fully confirm recent findings in mice. Show less
Hildebrand, R.B.; Lammers, B.; Meurs, I.; Korporaal, S.J.A.; Haan, W. de; Zhao, Y.; ... ; Eck, M. van 2010
Objective-Disruption of scavenger receptor class B type I (SR-BI) in mice impairs high-density lipoprotein (HDL)-cholesterol (HDL-C) delivery to the liver and induces susceptibility to... Show moreObjective-Disruption of scavenger receptor class B type I (SR-BI) in mice impairs high-density lipoprotein (HDL)-cholesterol (HDL-C) delivery to the liver and induces susceptibility to atherosclerosis. In this study, it was investigated whether introduction of cholesteryl ester transfer protein (CETP) can normalize HDL-C transport to the liver and reduce atherosclerosis in SR-BI knockout (KO) mice. Methods and Results-Expression of human CETP in SR-BIKO mice resulted in decreased plasma HDL-C levels, both on chow diet (1.8-fold, P < 0.001) and on challenge with Western-type diet (1.6-fold, P < 0.01). Furthermore, the presence of CETP partially normalized the abnormally large HDL particles observed in SR-BIKO mice. Unexpectedly, expression of CETP in SR-BIKO mice did not reduce atherosclerotic lesion development, probably because of consequences of SR-BI deficiency, including the persistence of higher VLDL-cholesterol (VLDL-C) levels, unchanged elevated free cholesterol/total cholesterol ratio, and the increased oxidative status of the animals. In addition, CETP expression did not normalize other characteristics of SR-BI deficiency, including female infertility, reticulocytosis, thrombocytopenia, and impaired platelet aggregation. Conclusion-CETP restores HDL-C levels in SR-BIKO mice, but it does not change the susceptibility to atherosclerosis and other typical characteristics that are associated with SR-BI disruption. This may indicate that the pathophysiology of SR-BI deficiency is not a direct consequence of changes in the HDL pool. (Arterioscler Thromb Vasc Biol. 2010; 30: 1439-1445.) Show less
Objective: The use of the HIV-protease inhibitor ritonavir (RTV) is associated with induction of hypertriglyceridemia, which is a cardiovascular risk factor. Therefore, we investigated the effect... Show moreObjective: The use of the HIV-protease inhibitor ritonavir (RTV) is associated with induction of hypertriglyceridemia, which is a cardiovascular risk factor. Therefore, we investigated the effect of RTV on atherosclerosis development in APOE*3-Leiden transgenic mice, a model for human-like lipoprotein metabolism and atherosclerosis. Methods and results: APOE*3-Leiden mice were fed a Western-type diet without or with RTV (35 mg/kg/day) for 19 weeks. RTV increased plasma TG levels throughout the study (similar to 2-fold; P < 0.05). Despite these increased TG levels, RTV decreased the atherosclerotic lesion area in the aortic root (-57%; P < 0.05), concomitant with reduced macrophage area (-72%; P < 0.01) and decreased lesion severity. This could not be explained by reduced inflammatory markers in plasma (i.e. serum amyloid A, E-selectin and fibrinogen), nor by decreased lipid accumulation in macrophages or increased cholesterol efflux from macrophages, as assessed using peritoneal macrophages in vitro. Rather, whereas RTV did not affect plasma total cholesterol levels, RTV decreased (V) LDL-cholesterol and increased cholesterol in apoE-rich large HDL. Conclusion: Despite inducing hypertriglyceridemia, RTV decreases atherosclerotic lesion area and severity, associated with decreased (V) LDL-cholesterol and increased atheroprotective apoE-rich large HDL. (C) 2009 Elsevier Ireland Ltd. All rights reserved. Show less
Objective-The iminosugar N-(5'-adamantane-1'-yl-methoxy)-pentyl-1-deoxynoijirimycin (AMP-DNM), an inhibitor of the enzyme glucosylceramide synthase catalyzing glycosphingolipid (GSL) biosynthesis,... Show moreObjective-The iminosugar N-(5'-adamantane-1'-yl-methoxy)-pentyl-1-deoxynoijirimycin (AMP-DNM), an inhibitor of the enzyme glucosylceramide synthase catalyzing glycosphingolipid (GSL) biosynthesis, ameliorates diabetes and reduces liver steatosis in ob/ob mice. Because an accumulation of sphingolipids, including sphingomyelin and GSLs, has been reported in atherosclerotic lesions in animal models and in humans, the objective of this study was to determine whether AMP-DNM also exerts beneficial effects on the development of atherosclerosis. Methods and Results-APOE*3 Leiden mice, maintained on a high-cholesterol diet, were treated for up to 18 weeks with AMP-DNM. The iminosugar prevented hyperlipidemia, generated a less atherogenic lipid profile, and induced a dramatic reduction in the development of atherosclerotic lesions. At the highest dose, no lesions were detectable. The effect of AMP-DNM was associated with a decrease in liver cholesterol, an increase in bile secretion, and enhanced excretion of cholesterol in the feces. Similar effects of AMP-DNM were observed in mice deficient for the low-density lipoprotein receptor. Conclusion-By lowering plasma cholesterol, the iminosugar AMP-DNM dramatically reduces the development of atherosclerosis in APOE*3 Leiden and low-density lipoprotein receptor -/- mice. Thus, targeting GSL synthesis may be a new treatment modality to prevent cardiovascular disease. (Arterioscler Thromb Vasc Biol. 2010;30:931-937.) Show less
Jonker, J.T.; Wang, Y.N.; Haan, W. de; Diamant, M.; Rijzewijk, L.J.; Meer, R.W. van der; ... ; Smit, J.W.A. 2010
Objective: Thiazolidinediones reduce hepatic steatosis and increase high-density lipoprotein (HDL)-cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic... Show moreObjective: Thiazolidinediones reduce hepatic steatosis and increase high-density lipoprotein (HDL)-cholesterol levels. In mice with human-like lipoprotein metabolism (APOE*3-Leiden.CETP transgenic mice), a decrease in hepatic triglyceride (TG) content is associated with a decrease in plasma cholesteryl ester transfer protein (CETP) mass and an increase in HDL levels. Therefore, the aim of the present study was to assess the effects of pioglitazone on CETP mass in patients with type 2 diabetes mellitus. Research Design and Methods: We included 78 men with type 2 diabetes mellitus (age 56.5+/-0.6 years; HbA1c 7.1+/-0.1%) who were randomized to treatment with pioglitazone (30 mg/day) or metformin (2000 mg/day) and matching placebos, in addition to glimepiride. At baseline and after 24 weeks of treatment plasma HDL-cholesterol levels and CETP mass were measured and hepatic TG content was assessed by proton magnetic resonance spectroscopy. Results: Pioglitazone decreased hepatic TG content (5.9 (2.6-17.4) vs. 4.1 (1.9-12.3)%, P<0.05), decreased plasma CETP mass (2.33+/-0.10 vs. 2.06+/-0.10 mug/mL, P<0.05) and increased plasma HDL-cholesterol levels (1.22+/-0.05 vs. 1.34+/-0.05 mM, P<0.05). Metformin did not significantly change any of these parameters. Conclusions: A decrease in hepatic TG content by pioglitazone is accompanied by a decrease in plasma CETP mass and associated with an increase in HDL-cholesterol levels. These results in patients with type 2 diabetes mellitus fully confirm recent findings in mice. Show less
Bijland, S.; Berg, S.A.A. van den; Voshol, P.J.; Hoek, A.M. van den; Princen, H.M.G.; Havekes, L.M.; ... ; Dijk, K.W. van 2010
The cholesteryl ester transfer protein (CETP) facilitates the bidirectional transfer of cholesteryl esters and triglycerides (TG) between HDL and (V) LDL. By shifting cholesterol in plasma from HDL... Show moreThe cholesteryl ester transfer protein (CETP) facilitates the bidirectional transfer of cholesteryl esters and triglycerides (TG) between HDL and (V) LDL. By shifting cholesterol in plasma from HDL to (V) LDL in exchange for VLDL-TG, CETP aggravates atherosclerosis in hyperlipidemic APOE*3-Leiden (E3L) mice. The aim of this study was to investigate the role of CETP in TG metabolism and high-fat diet-induced obesity by using E3L mice with and without the expression of the human CETP gene. On chow, plasma lipid levels were comparable between both male and female E3L and E3L. CETP mice. Further mechanistic studies were performed using male mice. CETP expression increased the level of TG in HDL. CETP did not affect the postprandial plasma TG response or the hepatic VLDL-TG and VLDL-apolipoprotein B production rate. Moreover, CETP did not affect the plasma TG clearance rate or organ-specific TG uptake after infusion of VLDL-like emulsion particles. In line with the absence of an effect of CETP on tissue-specific TG uptake, CETP also did not affect weight gain in response to a high-fat diet. In conclusion, the CETP-induced increase of TG in the HDL fraction of E3L mice is not associated with changes in the production of TG or with tissuespecific clearance of TG from the plasma.-Bijland, S., S. A. A. van den Berg, P. J. Voshol, A. M. van den Hoek, H. M. G. Princen, L. M. Havekes, P. C. N. Rensen, and K. Willems van Dijk. CETP does not affect triglyceride production or clearance in APOE*3-Leiden mice. J. Lipid Res. 2010. 51: 97-102 Show less
Out, R.; Kruijt, J.K.; Rensen, P.C.N.; Hildebrand, R.B.; Vos, P. de; Eck, M. van; Berkel, T.J.C. van 2004
