Hyperlipidemias: Dallinga-Thie GM

Dullaart RP, Dallinga-Thie GM, Wolffenbuttel BH, van Tol A. · University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. · Eur J Clin Invest. · Pubmed #17217373 No free full text.

Abstract: In view of the cardioprotective effect of high-density lipoproteins (HDL) and the limited effects of statin and fibrate therapy on HDL cholesterol, it is clinically relevant to test whether pharmacological treatment aimed at raising HDL lowers cardiovascular risk. Cholesteryl ester transfer protein (CETP) is a new therapeutic target, because the cholesteryl ester transfer process lowers HDL cholesterol and contributes to an atherogenic lipoprotein profile, particularly when plasma triglycerides are high. Clinical evidence suggests that coronary artery calcification as well as intima media thickness is positively related to plasma cholesteryl ester transfer, and that high plasma CETP concentration is associated with increased cardiovascular risk in hypertriglyceridaemia. However, CETP could also have anti-atherogenic potential, since it provides a potentially beneficial route for delivery of HDL-derived cholesteryl esters to the liver. In addition, CETP could also favourably stimulate peripheral cell cholesterol removal and enhance hepatic cholesterol uptake. Recent evidence suggests that a high CETP level may confer lower cardiovascular risk in the context of low triglycerides. At maximal doses, the CETP inhibitors JTT-705 and torcetrapib elicit a marked rise in HDL cholesterol of up to 34% and 91-106%, respectively. The effectiveness of these drugs on (intermediate) clinical outcome measures is currently being tested in large-scale phase III clinical trials, with torcetrapib being only evaluated in combination therapy with atorvastatin. When and how to use CETP inhibitors, e.g. in combination with a statin or a fibrate, is a major challenge. We propose that low HDL cholesterol in the context of high triglycerides, such as found in type 2 diabetes mellitus, could become an important indication area for this new class of drugs.

Twickler TB, Dallinga-Thie GM, Cohn JS, Chapman MJ. · Department of Internal Medicine, Medical Center, Utrecht, The Netherlands. · Circulation. · Pubmed #15117861 links to  free full text

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Twickler TB, Cramer MJ, Dallinga-Thie GM, Chapman MJ, Erkelens DW, Koppeschaar HP. · INSERM, Unité 551 Dyslipoproteinemia and Atherosclerosis, Hôpital Pitié-Salpetrière, 75651 Paris, France. · J Clin Endocrinol Metab. · Pubmed #12788843 links to  free full text

This publication has no abstract.

Dallinga-Thie GM, Berk-Planken II, Bootsma AH, Jansen H, Anonymous00173. · Department of Internal Medicine, University Medical Center Utrecht, Utrecht, the Netherlands. · Diabetes Care. · Pubmed #15161788 links to  free full text

Abstract: OBJECTIVE: Apolipoprotein (apo)C-III is a constituent of HDL (HDL apoC-III) and of apoB-containing lipoproteins (LpB:C-III). It slows the clearance of triglyceride-rich lipoproteins (TRLs) by inhibition of the activity of the enzyme lipoprotein lipase (LPL) and by interference with lipoprotein binding to cell-surface receptors. Elevated plasma LpB:C-III is an independent risk factor for cardiovascular disease. We studied the effect of atorvastatin on plasma LpB:C-III and HDL apoC-III. RESEARCH DESIGN AND METHODS: We studied the effect of 30 weeks' treatment with 10 and 80 mg atorvastatin on plasma apoC-III levels in a randomized, double-blind, placebo-controlled trial involving 217 patients with type 2 diabetes and fasting plasma triglycerides between 1.5 and 6.0 mmol/l. RESULTS: Baseline levels of total plasma apoC-III, HDL apoC-III, and LpB:C-III were 41.5 +/- 10.0, 17.7 +/- 5.5, and 23.8 +/- 7.7 mg/l, respectively. Plasma apoC-III was strongly correlated with plasma triglycerides (r = 0.74, P < 0.001). Atorvastatin 10- and 80-mg treatment significantly decreased plasma apoC-III (atorvastatin 10 mg, 21%, and 80 mg, 27%), HDL apoC-III (atorvastatin 10 mg, 22%, and 80 mg, 28%) and LpB:C-III (atorvastatin 10 mg, 23%, and 80 mg, 28%; all P < 0.001). The decrease in plasma apoC-III, mainly in LpB:C-III, strongly correlated with a decrease in triglycerides (atorvastatin 10 mg, r = 0.70, and 80 mg, r = 0.78; P < 0.001). Atorvastatin treatment also leads to a reduction in the HDL apoC-III-to-HDL cholesterol and HDL apoC-III-to-apoA-I ratios, indicating a change in the number of apoC-III per HDL particle (atorvastatin 10 mg, -21%, and 80 mg, -31%; P < 0.001). CONCLUSIONS: Atorvastatin treatment resulted in a significant dose-dependent reduction in plasma apoC-III, HDL apoC-III, and LpB:C-III levels in patients with type 2 diabetes. These data indicate a potentially important antiatherogenic effect of statin treatment and may explain (part of) the triglyceride-lowering effect of atorvastatin.

de Sauvage Nolting PR, Twickler MB, Dallinga-Thie GM, Buirma RJ, Hutten BA, Kastelein JJ, Anonymous00278. · Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands. · Circulation. · Pubmed #12176948 links to  free full text

Abstract: BACKGROUND: Remnant lipoproteins (RLP-C) are considered important in atherogenesis. Hence, this study was designed to assess RLP-C levels and the effect of statin therapy in patients with familial hypercholesterolemia (FH). Elevated RLP-C levels have been associated with the presence and progression of atherosclerotic disease, and their presence in FH patients has been proposed but never established in a large cohort, nor has their response to statin therapy been confirmed. METHODS AND RESULTS: FH patients were recruited from 36 lipid clinics. After a washout period of 6 weeks, all patients were started on monotherapy with 80 mg of simvastatin for 2 years. RLP-C levels were assessed by an immune-separation assay. In 327 FH patients, RLP-C measurements could be performed before and after treatment. Mean total cholesterol (10.55+/-2.17 mmol/L), mean LDL cholesterol (8.40+/-2.13 mmol/L), and median RLP-C (0.47 mmol/L) levels were all severely elevated at baseline. After treatment, RLP-C levels were reduced by 49% (0.24 mmol/L; P<0.0001). Even patients with normal triglyceride levels had elevated RLP-C levels at baseline, and those with high RLP-C levels were generally characterized by a very atherogenic lipoprotein profile. CONCLUSIONS: Baseline RLP-C levels are severely elevated in FH patients and are reduced by simvastatin but do not return to normal. These elevated RLP-C levels could be the consequence of impaired function of the LDL receptor in FH. RLP-C levels in FH contribute to an atherogenic lipoprotein profile and could identify patients who require additional treatment.

Krikken JA, Waanders F, Dallinga-Thie GM, Dikkeschei LD, Vogt L, Navis GJ, Dullaart RP. · University Medical Center Groningen, Division of Nephrology, Hanzeplein 1, Department of Internal Medicine, 9713 GZ Groningen, The Netherlands. · Expert Opin Ther Targets. · Pubmed #19397474 No free full text.

Abstract: OBJECTIVE: Dyslipidemia contributes to increased cardiovascular risk in nephrotic syndrome. We questioned whether reduction in proteinuria not only lowers low-density lipoprotein cholesterol (LDL-C), but also high-density lipoprotein cholesterol (HDL-C) and cholesteryl ester transfer protein (CETP) mass and whether changes in HDL-C were related to changes in plasma adiponectin. METHODS: Thirty-two non-diabetic proteinuric patients (12 on statin therapy), were followed during two double blind 6-week periods of placebo and treatment (low sodium + 100mg losartan + 25 mg hydrochlorothiazide). RESULTS: With placebo HDL-C was lower but LDL-C and CETP were not different in proteinuric patients compared with matched controls. LDL-C, HDL-C and CETP decreased upon proteinuria reduction. The decrease in LDL-C correlated with the drop in CETP and the degree of proteinuria reduction. HDL-C also decreased in proportion to proteinuria lowering. Individual changes in HDL-C were correlated with changes in adiponectin. CONCLUSION: LDL-C lowering upon robust reduction of proteinuria may be affected by changes in plasma CETP mass, but this treatment also decreases HDL-C in relation to the degree of proteinuria reduction. This adverse effect on HDL-C may in part be attributable to changes in adiponectin.

Beigneux AP, Franssen R, Bensadoun A, Gin P, Melford K, Peter J, Walzem RL, Weinstein MM, Davies BS, Kuivenhoven JA, Kastelein JJ, Fong LG, Dallinga-Thie GM, Young SG. · Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA. · Arterioscler Thromb Vasc Biol. · Pubmed #19304573 No free full text.

Abstract: OBJECTIVE: GPIHBP1 is an endothelial cell protein that binds lipoprotein lipase (LPL) and chylomicrons. Because GPIHBP1 deficiency causes chylomicronemia in mice, we sought to determine whether some cases of chylomicronemia in humans could be attributable to defective GPIHBP1 proteins. METHODS AND RESULTS: Patients with severe hypertriglyceridemia (n=60, with plasma triglycerides above the 95th percentile for age and gender) were screened for mutations in GPIHBP1. A homozygous GPIHBP1 mutation (c.344A>C) that changed a highly conserved glutamine at residue 115 to a proline (p.Q115P) was identified in a 33-year-old male with lifelong chylomicronemia. The patient had failure-to-thrive as a child but had no history of pancreatitis. He had no mutations in LPL, APOA5, or APOC2. The Q115P substitution did not affect the ability of GPIHBP1 to reach the cell surface. However, unlike wild-type GPIHBP1, GPIHBP1-Q115P lacked the ability to bind LPL or chylomicrons (d < 1.006 g/mL lipoproteins from Gpihbp1(-/-) mice). Mouse GPIHBP1 with the corresponding mutation (Q114P) also could not bind LPL. CONCLUSIONS: A homozygous missense mutation in GPIHBP1 (Q115P) was identified in a patient with chylomicronemia. The mutation eliminated the ability of GPIHBP1 to bind LPL and chylomicrons, strongly suggesting that it caused the patient's chylomicronemia.

van Oostrom AJ, Alipour A, Sijmonsma TP, Verseyden C, Dallinga-Thie GM, Plokker HW, Castro Cabezas M. · Department of Cardiology, St. Antonius Hospital, Nieuwegein, the Netherlands. · Neth J Med. · Pubmed #19155542 links to  free full text

Abstract: Postprandial hyperlipidaemia has been associated with coronary artery disease (CAD). We investigated which of the generally used methods to test postprandial lipaemia differentiated best between patients with premature CAD (50+/-4 years, n=20) and healthy controls. Furthermore, the effects of rosuvastatin 40 mg/day on postprandial parameters were assessed. Standardised oral fat-loading tests (OFLT) and ambulant self-measurements of daylong capillary triglycerides (TGc) were performed. Total responses of individual lipoproteins, plasma TG (TGp) and remnant-like particle cholesterol (RLP-C) were estimated as area under the curve (AUC). Most AUCs were highest in untreated patients and reached control levels after rosuvastatin. From all AUCs, RLP-C-AUC was best associated to TGp-AUC in untreated patients and controls (adjusted R2=0.84, beta=0.92, p.

Koeijvoets KC, Mooijaart SP, Dallinga-Thie GM, Defesche JC, Steyerberg EW, Westendorp RG, Kastelein JJ, van Hagen PM, Sijbrands EJ. · Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands. · Eur Heart J. · Pubmed #19098018 No free full text.

Abstract: AIMS: Activation of the complement system seems an important link between inflammation and atherogenesis. The Y402H polymorphism of complement factor H (CFH) has been associated with cardiovascular events, but results are conflicting and possibly modified by age of onset of cardiovascular disease (CVD). METHODS AND RESULTS: We determined whether or not the Y402H polymorphism influenced CVD risk in a multicentre cohort study involving 2,016 unrelated patients with familial hypercholesterolaemia (FH), who have an extremely increased susceptibility to premature CVD. We identified 261 individuals who were homozygous for the polymorphism (CC genotype; 12.9%), 929 individuals who were heterozygous (TC genotype; 46.1%), and 826 individuals carried the wild-type (TT genotype; 41.0%). During 95 115 person years, 644 patients had a cardiovascular event. Carriers of the CC genotype had a decreased risk of CVD (hazard ratio 0.67, 95% confidence interval 0.51-0.87; P = 0.003) relative to the other genotype groups. This association was unaltered after adjustment for clinically relevant cardiovascular risk factors or age effects. CONCLUSION: Among patients with severely increased risk of early onset CVD, the Y402H CFH variant was inversely associated with susceptibility to CVD. This suggests that CFH is a modifier gene of CVD.

Olijhoek JK, Hajer GR, van der Graaf Y, Dallinga-Thie GM, Visseren FL. · Department of Vascular Medicine, University Medical Centre Utrecht, Utrecht, The Netherlands. · J Cardiovasc Pharmacol. · Pubmed #18670365 No free full text.

Abstract: BACKGROUND AND AIMS: Insulin resistance is associated with postprandial hyperlipidemia and endothelial dysfunction. Patients with metabolic syndrome, characterized by insulin resistance, are at increased cardiovascular risk. The aim of the present study was to investigate whether a similar low-density lipoprotein cholesterol (LDL-c) reduction with combination therapy of low-dose simvastatin and ezetimibe or with high-dose simvastatin alone has similar effects on (post-fat load) endothelial function. METHODS: Randomized, double blind, crossover trial in 19 male obese patients with metabolic syndrome with high-dose simvastatin 80 mg versus combination therapy of low-dose simvastatin 10 mg with ezetimibe 10 mg. Fasting and post-fat load lipids and endothelial function (brachial artery flow-mediated dilation) were determined. RESULTS: Fasting LDL-c concentrations (2.1 +/- 0.5 mmol/L) and fasting endothelial function (6.9 +/- 0.8 vs. 7.6 +/- 1.2%) were the same after both treatments. Although post-fat load plasma triglycerides concentrations were higher (3.2 +/- 0.4 vs. 2.6 +/- 0.2 mmol x h/L) with combination therapy compared to monotherapy, ApoB particles were comparable (0.9 +/- 3.3 vs. -0.2 +/- 2.3 g x h/L). Combination therapy did not decrease post-fat load endothelial function (7.6 +/- 1.2 vs. 7.7 +/- 1.6%), contrary to high-dose simvastatin monotherapy (6.9 +/- 0.8 vs. 4.3 +/- 0.6%). CONCLUSIONS: Combination therapy with low-dose simvastatin and ezetimibe preserved post-fat load endothelial function, contrary to treatment with high-dose simvastatin monotherapy in male metabolic syndrome patients. There were no differences in fasting lipid profiles and endothelial function.

Pullinger CR, Aouizerat BE, Movsesyan I, Durlach V, Sijbrands EJ, Nakajima K, Poon A, Dallinga-Thie GM, Hattori H, Green LL, Kwok PY, Havel RJ, Frost PH, Malloy MJ, Kane JP. · Cardiovascular Research Institute, University of California, San Francisco, CA, USA. · J Lipid Res. · Pubmed #18441017 links to  free full text

Abstract: Apolipoprotein A-V (apoA-V) is an important regulator of plasma levels of triglyceride (TG) in mice. In humans, APOA5 genetic variation is associated with TG in several populations. In this study, we determined the effects of the p.185Gly>Cys (c.553G>T; rs2075291) polymorphism on plasma TG levels in subjects of Chinese ancestry living in the United States and in a group of non-Chinese Asian ancestry. The frequency of the less common cysteine allele was 4-fold higher (15.1% vs. 3.7%) in Chinese high-TG subjects compared with a low-TG group (Chi-square = 20.2; P < 0.0001), corresponding with a 4.45 times higher risk of hypertriglyceridemia (95% confidence interval, 2.18-9.07; P < 0.001). These results were replicated in the non-Chinese Asians. Heterozygosity was associated, in the high-TG group, with a doubling of TG (P < 0.001), mainly VLDL TG (P = 0.014). All eleven TT homozygotes had severe hypertriglyceridemia, with mean TG of 2,292 +/- 447 mg/dl. Compared with controls, carriers of the T allele had lower postheparin lipoprotein lipase activity but not hepatic lipase activity. In Asian populations, this common polymorphism can lead to profound adverse effects on lipoprotein profiles, with homozygosity accounting for a significant number of cases of severe hypertriglyceridemia. This specific apoA-V variant has a pronounced effect on TG metabolism, the mechanism of which remains to be elucidated.

van der Net JB, van Etten J, Yazdanpanah M, Dallinga-Thie GM, Kastelein JJ, Defesche JC, Koopmans RP, Steyerberg EW, Sijbrands EJ. · Department of Internal Medicine-D435, Erasmus MC, University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands. · Eur Heart J. · Pubmed #18413308 links to  free full text

Abstract: AIMS: Familial hypercholesterolaemia (FH) is characterized by premature coronary heart disease (CHD). However, the incidence of CHD varies considerably among FH patients. Genetic variation in the renin-angiotensin-aldosterone system (RAAS) and the adrenalin/noradrenalin system may be of importance in determining the CHD risk in FH, because of their involvement in CHD. We investigated the association between CHD risk and combined genetic variation in the RAAS and adrenalin/noradrenalin system. METHODS AND RESULTS: In 2190 FH patients, we genotyped six RAAS polymorphisms and five adrenalin/noradrenalin polymorphisms. For each patient, we calculated two gene-load scores by counting the number of risk genotypes within each pathway. Four of the six RAAS polymorphisms and none of the polymorphisms in the adrenalin/noradrenalin system were significantly associated with CHD (P < 0.05). The RAAS gene-load score was significantly associated with CHD (P(linear trend) < 0.001): in patients with a gene-load score of 5 or 6, the CHD risk was 2.3 times as high as in patients with a score of 0 or 1. The gene-load score of the adrenalin/noradrenalin system was not associated with CHD. CONCLUSION: Genetic variation in the RAAS contributes gene-dose dependently to CHD risk in patients with FH, whereas genetic variation in the adrenalin/noradrenalin system is not associated with CHD.

van der Net JB, Isaacs A, Dallinga-Thie GM, Kastelein JJ, Defesche JC, Steyerberg EW, Sijbrands EJ. · Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands. · J Hypertens. · Pubmed #18300856 No free full text.

Abstract: OBJECTIVE: Familial hypercholesterolemia is characterized by high plasma low-density lipoprotein cholesterol levels and premature coronary heart disease. Despite the monogenetic origin of familial hypercholesterolemia, the incidence of coronary heart disease varies considerably among patients, which is only partly explained by classical risk factors. Hypertension is an important risk factor for coronary heart disease that is associated with angiotensinogen levels. Therefore, we analyzed the angiotensinogen gene as a modifier gene for coronary heart disease risk in patients with familial hypercholesterolemia. METHODS: In a cohort of 1785 familial hypercholesterolemia patients, we reconstructed five frequent haplotypes of the angiotensinogen gene, based on four polymorphisms. The five haplotypes cover approximately 98% of the genetic diversity accounted for by these four polymorphisms. The associations between the haplotypes and coronary heart disease were analyzed with the haplo.stats program, adjusted for age, sex and smoking. RESULTS: Patients homozygous for the C allele of the 4072 T>C polymorphism had a 34% increased coronary heart disease risk (P = 0.017) compared to patients homozygous for the T allele. Haplotype H3, consisting of the minor allele of the 4072T>C polymorphism and the major alleles of the other polymorphisms, had a frequency of 15% and was associated with a 45% increased coronary heart disease risk (P = 0.006) compared to the wild-type haplotype H1. CONCLUSIONS: We conclude that genetic variation in the angiotensinogen gene contributes to coronary heart disease risk in patients with familial hypercholesterolemia.

de Haan W, van der Hoogt CC, Westerterp M, Hoekstra M, Dallinga-Thie GM, Princen HM, Romijn JA, Jukema JW, Havekes LM, Rensen PC. · Netherlands Organization for Applied Scientific Research-Quality of Life, Gaubius Laboratory, P.O. Box 2215, 2301 CE Leiden, The Netherlands. · Atherosclerosis. · Pubmed #17868678 No free full text.

Abstract: OBJECTIVE: In addition to lowering low-density lipoprotein (LDL)-cholesterol, statins modestly increase high-density lipoprotein (HDL)-cholesterol in humans and decrease cholesteryl ester transfer protein (CETP) mass and activity. Our aim was to determine whether the increase in HDL depends on CETP expression. METHODS AND RESULTS: APOE*3-Leiden (E3L) mice, with a human-like lipoprotein profile and a human-like responsiveness to statin treatment, were crossbred with mice expressing human CETP under control of its natural flanking regions resulting in E3L.CETP mice. E3L and E3L.CETP mice were fed a Western-type diet with or without atorvastatin. Atorvastatin (0.01% in the diet) reduced plasma cholesterol in both E3L and E3L.CETP mice (-26 and -33%, P<0.05), mainly in VLDL, but increased HDL-cholesterol only in E3L.CETP mice (+52%). Hepatic mRNA expression levels of genes involved in HDL metabolism, such as phospholipid transfer protein (Pltp), ATP-binding cassette transporter A1 (Abca1), scavenger receptor class B type I (Sr-b1), and apolipoprotein AI (Apoa1), were not differently affected by atorvastatin in E3L.CETP mice as compared to E3L mice. However, in E3L.CETP mice, atorvastatin down-regulated the hepatic CETP mRNA expression (-57%; P<0.01) as well as the total CETP level (-29%) and cholesteryl esters (CE) transfer activity (-36%; P<0.05) in plasma. CONCLUSIONS: Atorvastatin increases HDL-cholesterol in E3L.CETP mice by reducing the CETP-dependent transfer of cholesterol from HDL to (V)LDL, as related to lower hepatic CETP expression and a reduced plasma (V)LDL pool.

de Vries R, Groen AK, Perton FG, Dallinga-Thie GM, van Wijland MJ, Dikkeschei LD, Wolffenbuttel BH, van Tol A, Dullaart RP. · Department of Endocrinology, University Medical Centre Groningen, University of Groningen, PO Box 30.001, Groningen, 9700 RB, The Netherlands. · Atherosclerosis. · Pubmed #17275009 No free full text.

Abstract: We tested whether hypertriglyceridemia associated with type 2 diabetes mellitus is accompanied by alterations in pre beta-HDL, which are considered to be initial acceptors of cell-derived cholesterol, and by changes in the ability of plasma to promote cellular cholesterol efflux. In 28 hypertriglyceridemic and 56 normotriglyceridemic type 2 diabetic patients, and in 56 control subjects, we determined plasma lipids, HDL cholesterol and phospholipids, plasma pre beta-HDL and pre beta-HDL formation, phospholipid transfer protein (PLTP) activity, plasma cholesterol esterification (EST) and cholesteryl ester transfer (CET) and the ability of plasma to stimulate cholesterol efflux out of cultured human fibroblasts. HDL cholesterol and HDL phospholipids were lower, whereas plasma PLTP activity, EST and CET were higher in hypertriglyceridemic diabetic patients than in the other groups. Pre beta-HDL levels and pre beta-HDL formation were unaltered, although the relative amount of pre beta-HDL (expressed as % of total plasma apo A-I) was increased in hypertriglyeridemic diabetic patients. Cellular cholesterol efflux to plasma from hypertriglyceridemic diabetic patients was increased compared to efflux to normotriglyceridemic diabetic and control plasma, but efflux to normotriglyceridemic diabetic and control plasma did not differ. Multiple linear regression analysis demonstrated that cellular cholesterol efflux to plasma was positively and independently related to pre beta-HDL formation, PLTP activity and EST (multiple r=0.48), but not to the diabetic state. In conclusion, cholesterol efflux from fibroblasts to normotriglyceridemic diabetic plasma is unchanged. Efflux to hypertriglyceridemic diabetic plasma is enhanced, in association with increased plasma PLTP activity and cholesterol esterification. Unaltered pre beta-HDL formation in diabetic hypertriglyceridemia, despite low apo A-I, could contribute to maintenance of cholesterol efflux.

de Graaf J, van der Vleuten GM, ter Avest E, Dallinga-Thie GM, Stalenhoef AF. · Department of Medicine, Division of General Internal Medicine 463, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. · J Clin Endocrinol Metab. · Pubmed #17227806 links to  free full text

Abstract: CONTEXT: The traditional lipid and lipoprotein levels in patients with familial combined hyperlipidemia (FCH) are relatively mildly elevated and do not fully explain the increased risk of cardiovascular disease (CVD). In other populations, high remnant-like particles cholesterol (RLP-C) levels are an independent risk factor for CVD. OBJECTIVE: The objective of the study was to investigate whether plasma RLP-C concentrations are elevated in patients with FCH and contribute to the increased prevalence of CVD. DESIGN, SETTING, PARTICIPANTS: In this cross-sectional study, we studied RLP-C levels in 37 FCH families comprising 582 subjects, of whom 134 subjects were diagnosed FCH based on total cholesterol, triglyceride, and apolipoprotein-B levels. Plasma RLP-C concentrations were determined using an immune-separation technique. RESULTS: For both men and women, the mean plasma RLP-C concentration (mmol/liter) was 2-fold elevated in FCH patients [0.59 (0.54-0.66) and 0.40 (0.37-0.43), respectively] compared with both normolipidemic relatives [0.27 (0.26-0.29) in male and 0.22 (0.21-0.23) in female, all P<0.000]; and spouses [0.27 (0.23-0.31) in male and 0.24 (0.21-0.27) in female, all P<0.000]. Plasma RLP-C levels above the 90th percentile predicted prevalent CVD, independently of nonlipid cardiovascular risk factors [odds ratio 2.18 (1.02-4.66)] and triglyceride levels [odds ratio 2.35 (1.15-4.83)]. However, in both FCH patients and controls, RLP-C did not provide additional information about prevalent CVD over and above non-high-density lipoprotein cholesterol levels. CONCLUSIONS: Patients with FCH have 2-fold elevated plasma RLP-C levels, which add to the atherogenic lipid profile and contribute to the increased risk for CVD. However, for clinical practice, non-high-density lipoprotein cholesterol is the best predictor of prevalent CVD.

van der Steeg WA, Hovingh GK, Klerkx AH, Hutten BA, Nootenboom IC, Levels JH, van Tol A, Dallinga-Thie GM, Zwinderman AH, Kastelein JJ, Kuivenhoven JA. · Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands. · J Lipid Res. · Pubmed #17192423 links to  free full text

Abstract: It is unclear whether cholesteryl ester transfer protein (CETP) contributes to high density lipoprotein cholesterol (HDL-C) levels in hyperalphalipoproteinemia (HALP) in Caucasians. Moreover, even less is known about the effects of hereditary CETP deficiency in non-Japanese. We studied 95 unrelated Caucasian individuals with HALP. No correlations between CETP concentration or activity and HDL-C were identified. Screening for CETP gene defects led to the identification of heterozygosity for a novel splice site mutation in one individual. Twenty-five heterozygotes for this mutation showed reduced CETP concentration (-40%) and activity (-50%) and a 35% increase of HDL-C compared with family controls. The heterozygotes presented with an isolated high HDL-C, whereas the remaining subjects exhibited a typical high HDL-C/low-triglyceride phenotype. The increase of HDL-C in the CETP-deficient heterozygotes was primarily attributable to increased high density lipoprotein containing apolipoprotein A-I and A-II (LpAI:AII) levels, contrasting with an increase in both high density lipoprotein containing apolipoprotein A-I only and LpAI:AII in the other group. This study suggests the absence of a relationship between CETP and HDL-C levels in Caucasians with HALP. The data furthermore indicate that genetic CETP deficiency is rare among Caucasians and that this disorder presents with a phenotype that is different from that of subjects with HALP who have no mutation in the CETP gene.

van der Vleuten GM, Isaacs A, Zeng WW, ter Avest E, Talmud PJ, Dallinga-Thie GM, van Duijn CM, Stalenhoef AF, de Graaf J. · Department of Medicine, Division of General Internal Medicine, 463, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. · Biochim Biophys Acta. · Pubmed #17157483 No free full text.

Abstract: BACKGROUND: Familial combined hyperlipidemia (FCH) is the most common genetic lipid disorder with an undefined genetic etiology. Apolipoprotein A5 gene (APOA5) variants were previously shown to contribute to FCH. The aim of the present study was to evaluate the association of APOA5 variants with FCH and its related phenotypes in Dutch FCH patients. Furthermore, the effects of variants in the APOA5 gene on carotid intima-media thickness (IMT) and cardiovascular disease (CVD) were examined. MATERIALS AND METHODS: The study population consisted of 36 Dutch families, including 157 FCH patients. Two polymorphisms in the APOA5 gene (-1131T>C and S19W) were genotyped. RESULTS: Haplotype analysis of APOA5 showed an association with FCH (p=0.029), total cholesterol (p=0.031), triglycerides (p<0.001), apolipoprotein B (p=0.011), HDL-cholesterol (p=0.013), small dense LDL (p=0.010) and remnant-like particle cholesterol (p=0.001). Compared to S19 homozygotes, 19W carriers had an increased risk of FCH (OR=1.6 [1.0-2.6]; p=0.026) and a more atherogenic lipid profile, reflected by higher triglyceride (+22%) and apolipoprotein B levels (+5%), decreased HDL-cholesterol levels (-7%) and an increased prevalence of small dense LDL (16% vs. 26%). In carriers of the -1131C allele, small dense LDL was more prevalent than in -1131T homozygotes (29% vs. 16%). No association of the APOA5 gene with IMT and CVD was evident. CONCLUSION: In Dutch FCH families, variants in the APOA5 gene are associated with FCH and an atherogenic lipid profile.

Koeijvoets KC, van Rossum EF, Dallinga-Thie GM, Steyerberg EW, Defesche JC, Kastelein JJ, Lamberts SW, Sijbrands EJ. · Department of Internal Medicine, D435, Erasmus Medical Center, P.O. Box 2040, 3000 AC Rotterdam, The Netherlands. · J Clin Endocrinol Metab. · Pubmed #16849409 links to  free full text

Abstract: CONTEXT: Individuals with the functional ER22/23EK variant in the glucocorticoid receptor gene are relatively resistant to the downstream consequences of glucocorticoids. Evidence suggests that carriers have a more favorable cardiovascular risk profile, but the relationship between this ER22/23EK variant and cardiovascular disease has not been hitherto assessed. OBJECTIVE: We, therefore, determined whether carriership of the ER22/23EK improves cardiovascular disease risk in patients with severe hypercholesterolemia. DESIGN, SETTING, AND PARTICIPANTS: In a multicenter cohort study, 2024 patients with heterozygous familial hypercholesterolemia, aged 18 yr and older, were genotyped for the ER22/23EK polymorphism. Patients were identified at lipid clinics throughout The Netherlands between 1989 and 2002. MAIN OUTCOME MEASURES: The primary outcome measure was cardiovascular disease. RESULTS: Seventy-six (7.8%) of 977 men and 72 (6.9%) of 1047 women were carriers of the ER22/23EK variant. A total of 395 men and 247 women had a cardiovascular event. In contrast to expected results, we observed no significant association of the ER22/23EK variant with cardiovascular disease risk (men: relative risk, 0.75; 95% confidence interval, 0.50-1.14; P = 0.2; women: relative risk, 1.37; 95% confidence interval, 0.82-2.28; P = 0.2). However, we found a significant interaction between gender and the polymorphism on cardiovascular disease (P = 0.02). CONCLUSIONS: In this large cohort of individuals with very high risk of cardiovascular disease, the association between the functional ER22/23EK polymorphism and cardiovascular risk was not significant overall, although it varied significantly by gender.

Dallinga-Thie GM, van Tol A, Hattori H, van Vark-van der Zee LC, Jansen H, Sijbrands EJ, Anonymous00173. · Department of Vascular Medicine and Metabolism, Room Bd 277, Erasmus Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands. · Diabetologia. · Pubmed #16752169 No free full text.

Abstract: AIMS/HYPOTHESIS: Variation in the human apolipoprotein (APO) A5 gene (APOA5) is associated with elevated plasma triglycerides. However, data on the exact role of plasma concentrations of APOA5 in human triglyceride homeostasis are lacking. In the present study, we estimated plasma APOA5 levels in patients with type 2 diabetes at baseline and during atorvastatin treatment, a lipid-lowering treatment that results in a reduction in plasma triglycerides and APOC3. SUBJECTS, MATERIALS AND METHODS: Plasma APOA5 concentration was measured by ELISA in 215 subjects with type 2 diabetes, who were taken from the Diabetes Atorvastatin Lipid-lowering Intervention (DALI) study, a 30-week randomised, double-blind, placebo-controlled study, and given atorvastatin 10 mg or 80 mg daily. RESULTS: At baseline, average plasma APOA5 concentration was 25.7+/-15.6 mug/100 ml. Plasma APOA5 (R (s)=0.40), APOC3 (R (s)=0.72) and APOE (R (s)=0.45) were positively correlated with plasma triglyceride levels (all p<0.001). In multiple linear regression analysis, adjusted for age and sex, the variation in plasma triglycerides was explained mostly by APOC3 (52%) and only to a small extent by APOA5 (6%) and APOE (1%). Atorvastatin treatment decreased plasma triglycerides, APOA5, APOC3 and APOE (all p<0.0001). After treatment, APOC3 remained the major determinant of plasma triglyceride levels (59%), while the contributions of APOA5 and APOE were insignificant (2 and 3%). CONCLUSIONS/INTERPRETATION: Our findings reveal a positive association between plasma APOA5 and triglycerides in patients with type 2 diabetes. Treatment with atorvastatin decreased plasma APOA5, APOC3, APOE and triglycerides. In contrast to APOC3, APOA5 is not a major determinant of triglyceride metabolism in these patients.

de Vries R, Perton FG, Dallinga-Thie GM, van Roon AM, Wolffenbuttel BH, van Tol A, Dullaart RP. · Department of Endocrinology, University Medical Center Groningen, P.O. Box 30001, 9700 RB, Hanzeplein 1, Groningen, 9713 GZ Netherlands. · Diabetes. · Pubmed #16306375 links to  free full text

Abstract: We tested whether carotid artery intima-media thickness (IMT) is associated with plasma cholesteryl ester transfer (CET) and/or the plasma cholesteryl ester transfer protein (CETP) concentration in type 2 diabetic and control subjects. In 87 male and female subjects with type 2 diabetes (nonsmokers, no insulin or lipid-lowering drug treatment) and 82 control subjects, IMT, plasma CET, CETP mass, and lipids were determined. HDL cholesterol was lower, whereas IMT, pulse pressure, plasma triglycerides, and plasma CET and CETP concentration were higher in diabetic patients versus control subjects. In diabetic patients, plasma CET was positively determined by triglycerides (P < 0.001), non-HDL cholesterol (P < 0.001), CETP (P = 0.002), and the interaction between CETP and triglycerides (P = 0.004). In control subjects, plasma CET was positively related to triglycerides (P < 0.001) and non-HDL cholesterol (P < 0.001). HDL cholesterol was inversely related to plasma CET in each group (P < 0.01 for both). IMT was positively associated with plasma CET in diabetic (P = 0.05) and control (P < 0.05) subjects after adjustment for age, sex, and pulse pressure. No independent relationship with plasma CETP mass was found. Plasma CET is a positive determinant of IMT. Plasma CETP mass, in turn, is a determinant of CET with an increasing effect at higher triglycerides. These data, therefore, provide a rationale to evaluate the effects of CETP inhibitor treatment on plasma CET and on cardiovascular risk in diabetes-associated hypertriglyceridemia.

Keulen ET, Schaper NC, Houben AJ, van Lin JM, Lutgens I, Rijkers K, Dallinga-Thie GM, de Bruin TW. · Laboratory of Molecular Metabolism and Endocrinology, Department of Medicine, Cardiovascular Research Institute Maastricht, University Hospital Maastricht, The Netherlands. · Atherosclerosis. · Pubmed #12052483 No free full text.

Abstract: We determined whether abnormalities in the number of basal (BC) and post-occlusive (POC) capillaries are present in familial combined hyperlipidemia (FCHL), and investigated the possible relationship of BC and POC with lipids, remnant-like lipoprotein particles (RLP-C), blood pressure, and insulin resistance. Fifty age-matched subjects, 23 (12 men) hyperlipidemic, normotensive FCHL subjects and 27 (14 men) healthy controls participated in this study. Capillary density was measured just above the finger nailfold, before and after 4 min of arterial occlusion. The number of BC and POC were significantly lower in FCHL men compared with healthy men, 113.7+/-15.1 versus 132.0+/-18.0 (P=0.02) and 123+/-19.1 versus 142.3+/-18.3 (P=0.03), respectively. No differences were found between FCHL women and control women. In univariate analyses in FCHL men, BC was inversely correlated with total cholesterol (r=-0.63; P=0.05). POC tended to be inversely correlated with total cholesterol (r=-0.62; P=0.056). No univariate correlations (P>0.3) were observed between BC or POC and blood pressure or insulin resistance. Multivariate analyses revealed that logRLP-C was the only significant independent contributor to BC and POC. This is the first description of a reduction in skin capillaries in FCHL men, which was associated with increased atherogenic lipoprotein levels. Loss of capillary surface may be important in the pathophysiology or can result from adaptation to the hyperlipidemia in FCHL.

Groenendijk M, Cantor RM, Funke H, Dallinga-Thie GM. · Department of Internal Medicine, University Medical Center Utrecht, 3508 GA Utrecht, the Netherlands. · Eur J Clin Invest. · Pubmed #11737222 No free full text.

Abstract: BACKGROUND: We previously reported linkage and association of the apoAI-CIII-AIV gene region on chromosome 11 with familial combined hyperlipidaemia (FCHL). However, the observed epistasis resulting in an increased susceptibility to FCHL still remains unexplained. We hypothesize that the region between the apo AI and apo CIII genes may harbour functional mutations that might be in linkage disequilibrium with the already identified SstI and MspI polymorphisms, and provide an alternative explanation for the observed relationship. METHODS: Using sequence analysis, we identified four new single nucleotide polymorphisms (SNPs) in the apo AI-CIII intergenic region. These four variants, T(3213)C, A(3235)C, T(3287)C and A(5132)C, were studied in 30 FCHL probands, 159 hyperlipidaemic relatives, 327 normolipidaemic relatives, and 218 spouses from the same families in which the original results were obtained. RESULTS: The allele frequencies were significantly different between probands and spouses (P < 0.05). Transmission/disequilibrium test (TDT) analyses revealed more frequent transmission of the minor alleles to the affected offspring. The minor genotype was associated with elevated plasma cholesterol and triglyceride levels. The T(3213)C and MspI, and the A(3235)C and SstI SNPs were in complete linkage disequilibrium, resulting in two different major haplotypes 2-2-1-2-2-1 and 1-1-2-2-2-2 (MspI-T(3213)C-A(3235)C-T(3287)C-A(5132)C-SstI). Both haplotypes appear to predispose to FCHL independently, and account, together with the wild-type, for almost 90% of those occurring in these FCHL families, extending the high-risk combination of haplotypes that were reported previously. CONCLUSION: These newly identified additional intergenic SNPs therefore provide an alternative explanation for the observed association of the SstI and MspI polymorphisms to the increased susceptibility for FCHL.

Groenendijk M, De Bruin TW, Dallinga-Thie GM. · Department of Internal Medicine, G02.228, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. · Atherosclerosis. · Pubmed #11583715 No free full text.

Abstract: Linkage and association of the apo AI-CIII-IV gene region to familial combined hyperlipidemia (FCHL) was reported previously, based on the presence of genetic variants in the apo CIII and apo AI gene. No data were available yet on the contribution of the apo A-IV locus. Two DNA variants in exon 3 of the apo A-IV gene, A (Thr)(347)T (Ser) and [CTGT](3-4) were characterized by sequencing the coding region of the apo A-IV gene and were analyzed in our Dutch FCHL cohort (30 probands, 159 affected relative, 317 unaffected relatives and 218 spouses). The genotype frequency of the A(347)T variant was different in probands and spouses. In probands no 2/2 carriers were found, resulting in a significant decreased frequency of the 2-allele (P<0.05). This was suggestive for a protective role of the presence of the serine (T) allele on the prevalence of FCHL. No difference in frequency distribution was found for the [CTGT](3-4) variant between the groups. Homozygous 4/4 carriers in spouses had a more favorable lipid profile (LDL-cholesterol and apo B, P<0.05). The absence of linkage disequilibrium of the A(347)T with other markers in the gene cluster, and the absence of linkage disequilibrium with [CTGT](3-4) marker and the MspI-AI marker in the apo A-I promoter showed that these two apo A-IV variants reside on different haplotypes from the apo A-I and apo C-III markers. This was illustrated by extensive haplotype analysis. The present data on the contribution of DNA variants in the apo A-IV gene support our previous observations that the apo AI-CIII-AIV gene cluster has a complex genetic contribution to FCHL both by conferring susceptibility and protection.

Dallinga-Thie GM, Groenendijk M, Blom RN, De Bruin TW, De Kant E. · Department of Internal Medicine, G02.228, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. · J Lipid Res. · Pubmed #11518765 links to  free full text

Abstract: In the present study, we have investigated the in vivo and in vitro role of two newly identified variants (G(-)944A and A(-)1180C) located in the upstream promoter region of the apolipoprotein C-III (apoC-III) gene. These variants were studied in 30 probands diagnosed with FCHL, their relatives, and spouses. The allele frequencies of both variants were not different between the groups. No significant associations between plasma lipid traits and DNA variants were observed. We further analyzed the effect of the presence of these variants in the upstream enhancing region of the apoC-III gene, as five different in vivo occurring haplotypes, on the transcriptional activity of apoC-III in both HepG2 and Caco-2 cells. All five promoter constructs, including the wild type, showed similar enhancing activity of the apoC-III gene. The average transcription efficiency was enhanced 19-fold in HepG2 cells and 11-fold in Caco-2 cells. Previous studies have shown in vitro insulin-dependent down-regulation of the apoC-III gene transcription in HepG2 cells by DNA variation in an insulin response element (IRE) in the apoC-III promoter. We observed a 30% insulin-dependent down-regulation of apoC-III expression that was, however, independent of the presence of the two IRE variants. In contrast, in Caco-2 cells, a more variable insulin-dependent up-regulation was found that was also independent of the presence of the IRE variants.In conclusion, our data suggested that the apoC-III gene transcription in vitro is regulated by insulin but independent of the presence of the two IRE variants at -455 and -482. We were unable to detect associations between these apoC-III variants and plasma lipids and insulin in our FCHL population. This means that in vivo apoC-III transcription not only depends upon insulin but appears to be mediated by other mechanisms.