Hyperlipidemias: Gylling H

Miettinen TA, Gylling H. · Department of Medicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland. · Am J Cardiol. · Pubmed #15992515 No free full text.

Abstract: Normal serum contains small amounts of noncholesterol sterols, including those reflecting cholesterol absorption and those that are markers of cholesterol synthesis. Absorption marker sterols include serum plant sterols, whereas cholesterol precursor sterols correlate with whole-body synthesis of cholesterol. Thus, serum noncholesterol sterols, and especially their ratios to cholesterol, can be used to evaluate the major features of cholesterol metabolism (ie, synthesis and absorption). Statin treatment reduces serum cholesterol precursors but increases serum plant sterols severalfold, especially in subjects with high-absorption marker sterol levels indicative of efficient cholesterol and sterol absorption in general. Statin therapy is most effective in subjects with high serum cholesterol precursor levels. In subjects with high-absorption sterol markers, dietary cholesterol absorption inhibition (eg, with plant stanol and sterol ester margarine) needs to be combined with a statin to achieve effective serum cholesterol reduction. However, whereas dietary plant stanol esters reduce statin-induced elevations of serum plant sterol levels, serum plant sterol levels remain elevated during dietary plant sterol ester consumption. The clinical implication of high serum plant sterol levels is under active investigation.

Gylling H. · Department of Clinical Nutrition, University of Kuopio, and Kuopio University Hospital, Kuopio, Finland. · Int J Clin Pract. · Pubmed #15529520 No free full text.

Abstract: Cardiovascular diseases are the principal causes of mortality in middle-aged people and in older people. Coronary heart disease (CHD) is the most common of the cardiovascular diseases; high serum levels of cholesterol are associated with atherosclerosis and an increased risk of CHD. Cholesterol homeostasis is achieved by means of a fine balance between cholesterol intake, absorption/excretion and synthesis. All of these processes are tightly linked and a change in one of them can significantly influence the others. Results from both experimental studies and clinical trials have shown that inhibition of cholesterol synthesis with a statin increases absorption and that conversely, inhibition of cholesterol absorption increases synthesis. The tight linkage of cholesterol absorption and synthesis in maintaining cholesterol homeostasis suggests that treatment with an agent that influences only one of these two processes is likely to have distinct limits with respect to its effects on cholesterol levels. Better understanding of cholesterol homeostasis, particularly the close interrelationship between cholesterol synthesis and absorption, may result in the design of rational integrated treatment regimens that employ multiple agents with complementary actions that attack multiple mechanisms to lower cholesterol.

Vuorio AF, Kovanen PT, Gylling H. · Department of Medicine, University of Helsinki and Helsinki University Central Hospital, PoBox 105, FIN-00029 HUS, Finland. · Expert Rev Cardiovasc Ther. · Pubmed #15151486 No free full text.

Abstract: In familial hypercholesterolemia, a defect in low-density lipoprotein receptors causes lifelong two- to threefold elevations in serum low-density lipoprotein-cholesterol levels. This leads to early atherosclerotic changes in infancy. Lifelong hypolipidemic treatment that can be started at a young age is thus greatly needed. Early diagnosis of familial hypercholesterolemia is important, and improved DNA tests for low-density lipoprotein receptor mutations have made it possible to carry out diagnosis at birth. A low saturated-fat, low cholesterol diet can be safely started at 7 months of age. This can be accompanied by dietary stanol esters from 2 years of age. At the age of 10, statin treatment can be safely started. In adults, more aggressive hypolipidemic treatment is required in order to reach the treatment goal for serum low-density lipoprotein-cholesterol levels less than 2.5 mmol/l. This can be achieved by using high doses of statin, or preferably by combining a statin with resin or ezetimibe (Zeita), Merck and Shering-Plough Pharmaceuticals). Once started, treatment of familial hypercholesterolemia is lifelong.

Miettinen TA, Gylling H. · Department of Medicine, Division of Internal Medicine, Universiry of Helsinki, Helsinki, Finland. · Ann Med. · Pubmed #15119832 No free full text.

Abstract: Statin trials have indicated that effective reduction of serum cholesterol should last up to one year before reduced risk of cardiovascular diseases can be detected. This observation can be applied most probably also to the use of plant stanol/sterol ester spreads for the treatment of hypercholesterolemia. However, despite the fact that the two spreads lower serum cholesterol similarly in short term studies, a comparison of one year results reveals an inconsistent effect of plant sterol spread as compared with that of plant stanol spread on cholesterol concentration in both men and women. This favors the use of plant stanol ester spread for long-term lowering of serum cholesterol. Doses of about 2 g/day of plant stanols as fatty acid ester spread enhances fecal elimination of cholesterol, but not of bile acids, through inhibition of cholesterol absorption by about 40%. This lowers serum total and low density lipoprotein (LDL) cholesterol despite enhanced compensatory increase in cholesterol synthesis by about 10% and 15% as compared with control spread, respectively, and by up to 20% as compared with the baseline diet. About one-third of mildly hypercholesterolemic subjects reach an accepted cholesterol level. A small dose of statin should be added to treatment in individuals resistant to monotherapy with plant stanol ester spread. A life-long consumption of plant stanol ester spread has been predicted to lower coronary events by about 20%.

Gylling H, Miettinen TA. · Department of Clinical Nutrition, University of Kuopio, Kuopio University Hospital, PL 1627, 70211 Kuopio, Finland. · Curr Opin Investig Drugs. · Pubmed #12498007 No free full text.

Abstract: Statins effectively inhibit cholesterol synthesis and are currently the most commonly used drugs for the treatment of hypercholesterolemia. However, patients with familial hypercholesterolemia and those unwilling to take, or who cannot tolerate statins, and patients with combined hyperlipidemia require a combination treatment. Statins combined with cholesterol malabsorption, caused, e.g., by plant stanol esters or ezetimibe (Schering-Plough Corp/Merck & Co Inc), or with bile acid malabsorption, caused by bile acid binding resins or guar gum, inhibit compensatory increases in cholesterol synthesis and effectively lower LDL cholesterol levels. Combination therapy of statins with fibrates should be controlled by lipidology experts. Recent information on indications and advantages of combining statins with n-3 fatty acids, hormone replacement therapy, or niacin, will also be discussed.

Vanhanen H, Gylling H, Miettinen TA. · KYS:n kliinisen ravitsemuksen yksikkö, sisätautien klinikka PL 1627, 70211 Kuopio. · Duodecim. · Pubmed #12462803 No free full text.

This publication has no abstract.

Miettinen TA, Gylling H. · Department of Medicine, University of Helsinki, Finland. · Curr Opin Lipidol. · Pubmed #10095984 No free full text.

Abstract: Renewal has occurred in the use of plant sterols for the treatment of hypercholesterolemias. A novel development was to convert plant sterols to corresponding stanols and esterify them to fat soluble form. In contrast to the crystalline plant sterols or stanols, plant stanol esters can be easily consumed during normal food intake in soluble form in different fat-containing food constituents when they have a potent cholesterol-lowering effect, shown in normo- and hypercholesterolemic men and women without or with coronary heart disease, children and diabetes. Cholesterol lowering is approximately 10% for total and 15% for LDL cholesterol, with the respective values for stanol ester margarine (2-3 g/day stanols) being 15% and 20%. Stanol esters reduce cholesterol absorption efficiency by up to 65%, increase cholesterol elimination in feces as cholesterol itself, usually not as bile acids, and stimulate cholesterol synthesis. Serum beta-carotene level is lowered, but no fat malabsorption or lowering of serum fat soluble vitamins have been observed. In contrast to plant sterols, stanols and their esters are minimally absorbed and they reduce serum plant sterol concentrations, also preventing statin-induced increase of plant sterols. Stanol ester margarine has been included in dietary treatment of hypercholesterolemia followed by the addition of drug treatment in resistant cases.

Hedman M, Miettinen TA, Gylling H, Ketomäki A, Antikainen M. · Hospital for Children and Adolescents, University of Helsinki, FIN-00029 HUS, Helsinki, Finland. · J Pediatr. · Pubmed #16492436 No free full text.

Abstract: OBJECTIVE: To assess causes for insufficient cholesterol-lowering response to pravastatin and plant stanol esters in children with heterozygous familial hypercholesterolemia (HeFH). STUDY DESIGN: Nine of 16 children with HeFH who had not reached normocholesterolemia (< or =194 mg/dL [< or =5 mmol/L]) by 1 year after treatment (40 mg pravastatin and plant stanol ester) were called nonresponders. The 7 remaining children were responders. Serum noncholesterol sterol ratios (10(2) x mmol/mol of cholesterol), surrogate estimates of cholesterol absorption (cholestanol, campesterol, sitosterol) and synthesis (desmosterol and lathosterol), were studied at study baseline (on plant stanol esters) and during combination therapy with pravastatin and plant stanol esters. RESULTS: Pravastatin decreased the serum levels of cholesterol and cholesterol synthesis markers, and increased the ratios of cholesterol absorption markers. Compared with the responders, the nonresponders had higher study baseline (on plant stanol esters) serum cholesterol concentrations (299 +/- 39 vs 251 +/- 35 mg/dL [7.7 +/- 1.0 vs 6.5 +/- 0.9 mmol/L]; P <.001) and higher respective ratios of campesterol (371 +/- 99 vs 277 +/- 67 10(2) x mmol/mol of cholesterol; P = .049) and sitosterol (176 +/- 37 vs 126 +/- 24 10(2) x mmol/mol of cholesterol; P = .008). The higher the ratio of cholestanol at study baseline, the smaller the 1-year percent reduction in cholesterol (r = .556; P = .025). CONCLUSIONS: Pravastatin treatment increases the markers of cholesterol absorption and decreases those of cholesterol synthesis in HeFH during simultaneous inhibition of cholesterol absorption. Combined inhibition of cholesterol absorption and synthesis may not normalize serum lipids in those patients with the highest cholesterol levels, especially if signs of enhanced cholesterol absorption are detectable.

Ketomäki A, Gylling H, Miettinen TA. · Division of Internal Medicine, Department of Medicine, University of Helsinki, Biomedicum Helsinki, P.O. Box 700, FIN-00029 HUS Helsinki, Finland. · Clin Chim Acta. · Pubmed #15149875 No free full text.

Abstract: BACKGROUND: While plant stanols are known to upregulate low density lipoprotein (LDL) receptors, we studied the effects of plant stanol (STA) and sterol (STE) ester spreads on triglyceride-rich lipoprotein (TRL) removal in statin-treated patients with familial hypercholesterolemia (FH) using intravenous Intralipid-squalene fat tolerance test. METHODS: Five patients consumed STA and STE in a randomized, crossover study for 4 weeks. TRL removal was studied at baseline and at the end of both periods. Serum, chylomicron (CM), and very low density lipoprotein lipids, squalene, and plant sterols were measured. RESULTS: LDL cholesterol was decreased by both spreads (15-16%, p<0.05). Plant sterol concentrations were doubled in serum and CM by STE vs. STA. After the injection of Intralipid, CM squalene and sitosterol, but not triglycerides (TG), reached higher peak levels (and area under the incremental curve (AUIC) of squalene) by both spreads than at baseline. Despite different plant sterol concentrations by STE vs. STA, the incremental curves for plant sterols were similar by the spreads. CONCLUSIONS: Despite the retarded removal of TRL lipids by STA and STE in the statin-treated subjects with FH, improvement of the fasting lipid profile was suggested important in consideration of combination of cholesterol absorption inhibitor with statins even in FH.

Ketomäki AM, Gylling H, Antikainen M, Siimes MA, Miettinen TA. · Division of Internal Medicine, Department of Medicine, and the Hospital for Children and Adolescents, University of Helsinki, Finland. · J Pediatr. · Pubmed #12756385 No free full text.

Abstract: OBJECTIVE: To show whether the ratios of squalene and cholesterol precursor sterols to cholesterol and cholestanol and plant sterols to cholesterol change differently in plasma and especially in the red cells of hypercholesterolemic children during consumption of plant stanol and sterol ester spreads. STUDY DESIGN: In a randomized, double-blind, crossover study, hypercholesterolemic children (n = 23) consumed low-fat plant stanol and sterol ester spreads for 5-week periods separated by a 5-week washout period. Plasma and red cell lipids, squalene, and noncholesterol sterols were measured before and at the end of each period. RESULTS: The plant stanol and sterol ester spreads lowered plasma total (-9% and -6%, respectively) and low-density lipoprotein (-12% and -9%) cholesterol but had no effect on red cell cholesterol, high-density lipoprotein cholesterol, or plasma triglycerides. The ratios of plasma and red cell sitosterol and campesterol to cholesterol decreased by 32% to 36% (P <.001) with the plant stanol ester and increased by 40% to 52% (P <.001) with the sterol ester spread. CONCLUSIONS: Consumption of plant sterols increases and consumption of plant stanols decreases the ratios of plant sterols to cholesterol in red cells of hypercholesterolemic children proportionately to the respective changes in plasma.

Hallikainen MA, Sarkkinen ES, Gylling H, Erkkilä AT, Uusitupa MI. · Department of Clinical Nutrition, University of Kuopio, Kuopio, Finland. · Eur J Clin Nutr. · Pubmed #11002384 No free full text.

Abstract: OBJECTIVE: To investigate cholesterol-lowering effects of stanol ester (STAEST) and sterol ester (STEEST)-enriched margarines as part of a low-fat diet. DESIGN: According to a Latin square model randomized double-blind repeated measures design with three test margarines and three periods. SETTING: Outpatient clinical trial with free-living subjects. SUBJECTS: Thirty-four hypercholesterolaemic subjects completed the study. Interventions: Subjects consumed three rapeseed oil-based test margarines (STAEST, STEEST and control (no added stanols or sterols)) as part of a low-fat diet each for 4 weeks. RESULTS: Mean daily intake of total plant sterols plus stanols was 2.01-2.04 g during the two test margarine periods. In reference to control, serum total cholesterol was reduced by 9.2 and 7.3% with the STAEST and STEEST margarine, respectively (P<0.001 for both). The respective reductions for low-density lipoprotein (LDL) cholesterol were 12.7 and 10.4% (P<0. 001). The cholesterol-lowering effects of the test margarines did not differ significantly. The presence of apolipoprotein E4 allele had a significant effect on LDL cholesterol response during the STAEST margarine only. Serum sitosterol and campesterol increased by 0.83 and 2.77 mg/l with the STEEST (P<0.001), respectively and decreased by 1.18 and 2.60 mg/l with the STAEST margarine (P<0.001). Increases of serum sitostanol and campestanol were 0.11 and 0.19 mg/l with the STAEST margarine (P<0.001), repsectively. No significant changes were found in serum fat-soluble vitamin and carotenoid concentrations when related to serum total cholesterol. CONCLUSIONS: STAEST and STEEST margarines reduced significantly and equally serum total and LDL cholesterol concentrations as part of a low-fat diet. SPONSORSHIP: Grant to the University of Kuopio by Raisio Benecol Ltd, Raisio, Finland.

Vuorio AF, Gylling H, Turtola H, Kontula K, Ketonen P, Miettinen TA. · Department of Medicine, University of Helsinki, Helsinki, Finland. · Arterioscler Thromb Vasc Biol. · Pubmed #10669649 links to  free full text

Abstract: In heterozygous familial hypercholesterolemia (FH), serum low density lipoprotein (LDL) cholesterol levels are already elevated at birth. Premature coronary heart disease occurs in approximately 30% of heterozygous untreated adult patients. Accordingly, to retard development of atherosclerosis, preventive measures for lowering cholesterol should be started even in childhood. To this end, 19 FH families consumed dietary stanol ester for 3 months. Stanol ester margarine lowers the serum cholesterol level by inhibiting cholesterol absorption. Each individual in the study replaced part of his or her daily dietary fat with 25 g of 80% rapeseed oil margarine containing stanol esters (2.24 g/d stanols, mainly sitostanol). The families who consumed this margarine for 12 weeks included 24 children, aged 3 to 13 years, with the North Karelia variant of FH (FH-NK), 4 FH-NK parents, and 16 healthy family members, and a separate group of 12 FH-NK adults who consumed the margarine for 6 weeks and who were on simvastatin therapy (20 or 40 mg/d). Fat-soluble vitamins were measured by high-pressure liquid chromatography, and cholesterol precursor sterols (indexes of cholesterol synthesis) and cholestanol and plant sterols (indexes of cholesterol absorption efficiency) were assayed by gas-liquid chromatography. No side effects occurred. Serum LDL cholesterol levels were reduced by 18% (P<0.001), 11%, 12% (P<0.001), and 20% (P<0.001) in the 4 groups, respectively. The serum campesterol-to-cholesterol ratios fell by 31% (P<0.001), 29%, 23% (P<0.001), and 36% (P<0.001), respectively, suggesting that cholesterol absorption efficiency was inhibited. Serum lathosterol ratios were elevated by 38% (P<0.001), 11%, 15% (P<0.001), and 19% (P<0.001), respectively, suggesting that cholesterol synthesis was compensatorily upregulated. The FH-NK children increased their serum lathosterol ratio more than did the FH-NK adults treated with stanol ester margarine and simvastatin (P<0.01). In the FH-NK children, serum retinol concentration and alpha-tocopherol-to-cholesterol ratios were unchanged by stanol ester margarine, but alpha- and beta-carotene concentrations and ratios were decreased. As assayed in a genetically defined population of FH patients, a dietary regimen with stanol ester margarine proved to be a safe and effective hypolipidemic treatment for children and adults. In FH-NK adults on simvastatin therapy, serum LDL cholesterol levels could be reduced even further by including a stanol ester margarine in the regimen.

Gylling H, Puska P, Vartiainen E, Miettinen TA. · Department of Medicine, University of Helsinki, Finland. · Atherosclerosis. · Pubmed #10488954 No free full text.

Abstract: We have shown earlier that sitostanol ester margarine lowers serum cholesterol by inhibiting cholesterol absorption so that, theoretically, there could be interference with the absorption of fat-soluble vitamins. Accordingly, we investigated whether sitostanol ester margarine affects the serum levels of vitamin D, retinol, alpha-tocopherol and alpha- and beta-carotenes during 1-year treatment in 102 subjects and 49 controls with moderate hypercholesterolemia. The vitamins were assayed at baseline on home diet, on margarine alone, after 1 year's consumption of sitostanol ester margarine and after an additional 2 months on home diet. In the sitostanol group, serum plant sterols, indicators of cholesterol absorption efficiency, were reduced up to -38% in relation to controls from home diet (P < 0.01) indicating that cholesterol absorption was markedly reduced. Vitamin D and retinol concentrations and the ratio of alpha-tocopherol to cholesterol were unchanged by sitostanol ester. Serum beta-carotenes and alpha-carotene concentration but not proportion were reduced in the sitostanol group from baseline and in relation to controls (P < 0.01). Retinol and vitamin D were unassociated with serum cholesterol, plant sterols or other vitamins, whereas alpha-tocopherol and carotenes were significantly associated with serum plant sterols suggesting that the higher cholesterol absorption efficiency, the higher the alpha-tocopherol and carotene levels in serum. We conclude that sitostanol ester did not affect vitamin D and retinol concentrations and alpha-tocopherol/cholesterol proportion, but reduced serum beta-carotene levels. Alpha-tocopherol and carotenes, but not vitamin D and retinol, were related to serum cholesterol and cholesterol absorption.

Lindbohm N, Gylling H, Miettinen TE, Miettinen TA. · Department of Medicine, University of Helsinki, Finland. · Clin Chim Acta. · Pubmed #10481924 No free full text.

Abstract: Low density lipoprotein (LDL) with low sialic acid content has been shown to cause intracellular lipid accumulation and therefore is suggested to be atherogenic. We investigated the sialic acid content of total LDL and its subfractions, and their relations to lipoprotein kinetics in 22 subjects with primary moderate hypercholesterolemia (IIa) and in 21 subjects with combined hyperlipidemia (IIb) matched for age, sex, BMI and the frequency of coronary artery disease. Sialic acid to protein ratio decreased gradually from VLDL and IDL to light and dense LDL and HDL, but was high in very dense LDL probably due to presence of Lp(a). Sialic acid to apo B ratio was significantly lower in dense and very dense subfractions of IIb than IIa. The sialic acid/apo B ratios of dense and very dense LDL subfractions were interrelated and were negatively associated with their cholesterol and triglyceride concentrations, and with the transport rate (TR) for dense LDL apo B. The only metabolic variable differing between the groups was the TR for dense LDL apo B, which was significantly higher in IIb vs. IIa. In addition, the TR for dense LDL apo B was positively associated with the esterification percentage of LDL cholesterol. In conclusion, low sialic acid content in dense and very dense LDL subfractions was associated with enhanced TR for LDL apo B and type IIb dyslipidemia.

Gylling H, Puska P, Vartiainen E, Miettinen TA. · Department of Medicine, University of Helsinki, P.O. Box 340, FIN-00029 HYKS, Helsinki, Finland. · J Lipid Res. · Pubmed #10191283 links to  free full text

Abstract: We investigated the changes of cholesterol and non-cholesterol sterol metabolism during plant stanol ester margarine feeding in 153 hypercholesterolemic subjects. Rapeseed oil (canola oil) margarine without (n = 51) and with (n = 102) stanol (2 or 3 g/day) ester was used for 1 year. Serum sterols were analyzed with gas-liquid chromatography. The latter showed a small increase in sitostanol peak during stanol ester margarine eating. Cholestanol, campesterol, and sitosterol proportions to cholesterol were significantly reduced by 5-39% (P < 0.05 or less for all) by stanol esters; the higher their baseline proportions the higher were their reductions. The precursor sterol proportions were significantly increased by 10- 46%, and their high baseline levels predicted low reduction of serum cholesterol. The decrease of the scheduled stanol dose from 3 to 2 g/day after 6-month feeding increased serum cholesterol by 5% (P < 0. 001) and serum plant sterol proportions by 8-13% (P < 0.001), but had no consistent effect on precursor sterols. In twelve subjects, the 12-month level of LDL cholesterol exceeded that of baseline; the non-cholesterol sterol proportions suggested that stimulated synthesis with relatively weak absorption inhibition contributed to the non-responsiveness of these subjects. In conclusion, plant stanol ester feeding lowers serum cholesterol in about 88% of subjects, decreases the non-cholesterol sterols that reflect cholesterol absorption, increases the sterols that reflect cholesterol synthesis, but also slightly increases serum plant stanols. Low synthesis and high absorption efficiency of cholesterol results in the greatest benefit from stanol ester consumption.

Gylling H, Hallikainen M, Raitakari OT, Laakso M, Vartiainen E, Salo P, Korpelainen V, Sundvall J, Miettinen TA. · Department of Clinical Nutrition, University of Kuopio, Kuopio, Finland. · Br J Nutr. · Pubmed #19019257 No free full text.

Abstract: Polymorphisms of the ABCG5 and ABCG8 genes interfere with cholesterol absorption and synthesis. We determined whether common polymorphisms of these genes regulate the responses of serum cholesterol and vascular function during long-term inhibition of cholesterol absorption. Mildly to moderately hypercholesterolaemic subjects (n 282) completed a 1-year study consuming plant stanol or sterol ester (2 g stanol or sterol) or control spread. Serum cholesterol and non-cholesterol sterols, markers of cholesterol absorption and synthesis, and variables of vascular function and structure were analysed in relation to common polymorphisms of ABCG5 and ABCG8. At baseline, subjects with the 54K allele of ABCG8 had higher brachial endothelial-dependent flow-mediated dilatation than those without it (5.79 (se 0.31) v. 4.46 (se 0.44) %; P = 0.049), and subjects with the 632V allele of ABCG8 had larger brachial artery diameter than those without it. Polymorphisms of ABCG5 and ABCG8 were neither associated with serum cholesterol reduction nor changes in cholesterol metabolism or in vascular function. However, in subjects with the 400K allele of ABCG8, intima media thickness (IMT) was increased in all groups more than in those without it (P < 0.05). In conclusion, serum cholesterol lowering with absorption inhibition was not associated with polymorphic sites of ABCG5 and ABCG8. However, regulation of baseline cholesterol metabolism and vascular function and structure, and IMT progression during 1 year seemed to share some of the common polymorphic sites of these genes, suggesting a gene-regulated interaction between cholesterol metabolism and vascular function and structure.

Berthold HK, Laaksonen R, Lehtimäki T, Gylling H, Krone W, Gouni-Berthold I. · Medical Faculty of the University of Bonn, Clinical Pharmacology, Bonn, Germany. · Exp Clin Endocrinol Diabetes. · Pubmed #18072016 No free full text.

Abstract: OBJECTIVE: Sterol regulatory binding proteins 1 and 2 (SREBPs) are transcription factors regulating lipid metabolism. A recent study has associated the CC genotype of the SREBP-1c polymorphism G952G with increased cholesterol synthesis. Further evidence suggests that SREBPs play a role in cholesterol absorption and that SREBP polymorphisms modulate the response to statin therapy. The present study examines whether the G952G polymorphism alters cholesterol synthesis and/or absorption and whether it modulates the response to widely used lipid-lowering drugs such as inhibitors of cholesterol synthesis (simvastatin) or absorption (ezetimibe). METHODS: Seventy-two healthy male subjects with LDL cholesterol <190 mg/dL participated in the study. Twenty four subjects were treated with ezetimibe (10 mg), simvastatin (40 mg) or their combination, respectively, for two weeks. Blood was drawn before and after the 2-week treatment period. RESULTS: Eleven CC homozygous carriers of the gene were found (15%).There were no differences in cholesterol synthesis or absorption between the CC homozygotes and the G allele-carriers, as measured by the ratios to cholesterol of serum lathosterol, desmosterol and cholestenol (synthesis markers) and cholestanol, sitosterol and campesterol (absorption markers). Ezetimibe had a significantly more potent effect in blocking cholesterol absorption in the CC homozygotes compared to the G-carriers ( P=0.002). CONCLUSIONS: The G/C (G952G) polymorphism of the SREBP-1 gene is not associated with cholesterol synthesis or absorption in a German male population. The CC homozygotes have a significantly increased response to the effects of ezetimibe on cholesterol absorption compared to the G allele-carriers, suggesting that SREBP-1 may be implicated in ezetimibe's mechanism of action.

Gouni-Berthold I, Berthold HK, Gylling H, Hallikainen M, Giannakidou E, Stier S, Ko Y, Patel D, Soutar AK, Seedorf U, Mantzoros CS, Plat J, Krone W. · Department of Internal Medicine II, University of Cologne, Kerpener Street 62, 50937 Cologne, Germany. · Atherosclerosis. · Pubmed #17980884 No free full text.

Abstract: OBJECTIVE: The combination of simvastatin, an HMG-CoA reductase inhibitor, and ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, decreases cholesterol synthesis and absorption and reduces circulating LDL-cholesterol concentrations. The molecular mechanisms underlying the pronounced lipid-lowering effects of this combination have not been fully elucidated in humans. METHODS AND RESULTS: One center, prospective, randomized, parallel three-group study in 72 healthy men (mean age 32+/-9 years, mean body mass index 25.7+/-3.2 kg/m(2)). Each group of twenty-four subjects received a 14-day treatment with either ezetimibe (10mg/day), simvastatin (40 mg/day) or their combination. Lipid levels, the ratio of non-cholesterol sterols to cholesterol concentrations (used as markers of cholesterol synthesis and absorption), cell surface LDL receptor (LDLR) protein as well as LDLR and HMG-CoA reductase gene expression in mononuclear blood cells were measured at baseline and at the end of the study. LDL-C decreased in all groups. Simvastatin decreased, ezetimibe increased and their combination had no effect on HMG-CoA reductase activity. Simvastatin and the combination of ezetimibe and simvastatin increased the HMG-CoA reductase and LDLR gene expression while ezetimibe had no effect. The cell surface LDLR protein expression remained unchanged in all groups. The combination of ezetimibe and simvastatin increased the expression of the serine protease proprotein convertase subtilisin/kexin 9 (PCSK9), an enzyme shown to down-regulate LDLR protein levels. CONCLUSIONS: The co-administration of ezetimibe and simvastatin abrogates the ezetimibe-induced increase in cholesterol synthesis and up-regulates the LDLR gene but not protein expression, an effect possibly mediated through a parallel upregulation of PCSK9 expression.

Hallikainen M, Lyyra-Laitinen T, Laitinen T, Agren JJ, Pihlajamäki J, Rauramaa R, Miettinen TA, Gylling H. · Department of Clinical Nutrition, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland. · Atherosclerosis. · Pubmed #16386259 No free full text.

Abstract: We investigated the effects of stanol (STAEST) and sterol esters (STEEST) on endothelial function in hypercholesterolemic subjects. In addition, associations of variables of cholesterol metabolism with endothelial function were investigated. In a double-blind randomized cross-over study (n=39) with age-matched parallel control group (n=37) the subjects consumed STAEST or STEEST spread (total plant sterols and stanols 1.93-1.98g/day) for 10 weeks each. Controls consumed the spread without sterols or stanols for 20 weeks. At baseline, brachial artery diameter was positively correlated with serum triglycerides (r=0.375, p=0.001) and glucose (r=0.420, p<0.001) and with cholesterol synthesis marker ratios to cholesterol (e.g. desmosterol r=0.540, p<0.001) and negatively with HDL cholesterol (r=-0.309, p=0.008) and absorption marker ratios (e.g. campesterol r=-0.332, p=0.004). During the intervention, LDL cholesterol was reduced by 6-9% from baseline with STAEST and STEEST spreads (p<0.05), and by 9-12%, respectively, from controls (p<0.05). Flow-mediated dilatation did not change during the investigation. Brachial artery diameter was unchanged in controls and during STAEST periods, but it was reduced during STEEST by 2.2% (p=0.012) from STAEST. In conclusion, variables of cholesterol metabolism are associated with brachial artery diameter at baseline. STEEST diminishes brachial artery diameter, but its clinical relevance remains unclear.

Ketomäki A, Gylling H, Miettinen TA. · Division of Internal Medicine, Department of Medicine, University of Helsinki, Finland; Biomedicum Helsinki, P.O. Box 700, FIN-00029 HUS, Finland. · Clin Chim Acta. · Pubmed #15698593 No free full text.

Abstract: BACKGROUND: Serum plant sterol levels are increased by consumption of statins and dietary plant sterols, and decreased by dietary plant stanols, but little is known about combination therapy of statin and plant sterols. METHODS: We measured plant sterols in serum, lipoproteins, and red cells in subjects with familial hypercholesterolemia (FH) (n=18) treated with variable doses of statins off and on plant stanol (STA) and sterol ester (STE) spreads. RESULTS: STA and STE spreads lowered LDL cholesterol approximately 15%. Plant sterols were decreased in serum, lipoproteins, and red cells by approximately 25% with STA and increased from 37% to 80% with STE, especially with high statin doses. The changes in serum were related to those in red cells. The baseline levels of serum plant sterols were negatively (r-range -0.639 to -0.935) and positively (r-range 0.526 to 0.598) correlated with the respective changes evoked by the STA and STE spreads. CONCLUSIONS: STE reduces LDL cholesterol, but increases serum, lipoprotein, and red cell plant sterol levels in statin-treated FH subjects, while all the respective values are decreased with STA. Recent predictions that elevated serum plant sterols pose an increased coronary risk suggest that increases of serum plant sterol levels should be avoided, especially in atherosclerosis-prone individuals, such as subjects with FH.

Gylling H, Hallikainen M, Pihlajamäki J, Agren J, Laakso M, Rajaratnam RA, Rauramaa R, Miettinen TA. · Department of Clinical Nutrition, University of Kuopio, Kuopio University Hospital, Kuopio, Finland. · J Lipid Res. · Pubmed #15175352 links to  free full text

Abstract: The roles of polymorphisms of the sitosterolemia genes ABCG5 and ABCG8 in the regulation of cholesterol metabolism and insulin sensitivity were studied in mildly hypercholesterolemic noncoronary subjects (n = 263, 144 men and 119 women) divided into tertiles by baseline serum cholestanol-to-cholesterol ratio (< or = 118.3 and > or = 147.7 10(2) x mmol/mol cholesterol), a surrogate marker of cholesterol absorption efficiency. The lowest cholestanol tertile was associated with high body mass index (BMI), plasma glucose, serum insulin and triglycerides, and cholesterol synthesis markers (cholestenol, desmosterol, lathosterol) and low HDL cholesterol and cholesterol absorption markers (campesterol, sitosterol) (P < 0.01 for all). The 19H allele of the ABCG8 gene accumulated in the lowest cholestanol tertile (P < 0.001) and was associated with low total and LDL cholesterol and absorption markers and with high synthesis markers (P < 0.05 for all). The 604E allele of the ABCG5 gene in men was associated with high BMI, plasma insulin, low serum sitosterol, and high serum cholestenol levels (P < 0.05 for all). In a subgroup of 71 men, the 604E allele was associated with insulin resistance measured with the hyperinsulinemic euglycemic clamp. In conclusion, low cholesterol absorption efficiency was associated with characteristics of the metabolic syndrome. Low serum cholesterol and cholesterol absorption were linked to the D19H polymorphism of the ABCG8 gene, and characteristics of the insulin resistance syndrome in men were linked with the Q604E polymorphism of the ABCG5 gene.

Ketomaki A, Gylling H, Miettinen TA. · Division of Internal Medicine and Biomedicum Helsinki, University of Helsinki, FIN-00029 HUS, Helsinki, Finland. · J Lab Clin Med. · Pubmed #15085084 No free full text.

Abstract: We studied the concentrations and ratios to cholesterol of noncholesterol sterols reflecting absorption (eg, campesterol) or synthesis (eg, lathosterol) of cholesterol off and on plant sterol and stanol ester spreads in serum and in different lipoproteins of a family with familial hypercholesterolemia, including heterozygous parents receiving no treatment and their homozygous offspring undergoing long-term treatment with statins and apheresis. Serum cholesterol levels were similar in the homozygous and heterozygous individuals, but the concentrations of sterols reflecting cholesterol absorption were as much as 10 times greater in the homozygous child than in the heterozygous parents, whereas the respective markers of cholesterol synthesis only tended to be higher. About 70% of squalene in the homozygous individual (60% in the heterozygous family members) and 85% to 90% of noncholesterol sterols (60%-80% in the heterozygous subjects) were transported by low-density lipoprotein. The ratios of absorption sterols to cholesterol were higher in high-density lipoprotein (HDL) than in very low-density lipoprotein (VLDL), whereas those of synthesis markers and plant stanols were highest in VLDL. The ratios of absorption sterols in serum were mostly lower than those in HDL but higher than in VLDL, whereas the ratios of synthesis sterols in serum were lower than they were in VLDL. Both spreads reduced serum total cholesterol by about 14% in the heterozygous family members and 9% in the homozygous individual. The sterol ester spread increased serum plant sterol concentrations (eg, campesterol in the homozygous family member increased from 5 to 9 mg/dL) and the ratios to cholesterol, but the stanol ester spread decreased them. Plant sterol esters seemed to similarly decrease serum cholesterol in this family with familial hypercholesterolemia, but the clinical role of increased plant sterol concentrations, almost doubled in the LDL of homozygous individuals, is not known.

Miettinen TA, Gylling H. · University of Helsinki, Helsinki, Finland. · Eur J Clin Invest. · Pubmed #14636301 No free full text.

Abstract: BACKGROUND: Serum contains noncholesterol sterols, which are reliable markers of cholesterol metabolism, but their presence and importance in different lipoproteins have been insufficiently studied. MATERIALS AND METHODS: Serum and lipoprotein cholesterol precursors squalene, cholestanol, desmosterol and lathosterol (markers of cholesterol synthesis) and cholestanol and plant sterols (markers of cholesterol absorption), and absorption efficacy and absolute synthesis of cholesterol were studied at baseline and during 6-month atorvastatin (80 mg day(-1)) treatment by the sterol balance technique in men with type 2 diabetes. RESULTS: At baseline, approximately 14% of serum squalene was transported by VLDL, 12% by IDL, 40% by LDL and 30% by HDL. The respective values for the noncholesterol sterols were approximately 8, 4, 61 and 26%. The squalene to cholesterol ratios were highest in VLDL and IDL, those of cholestanol, desmosterol and absorption marker sterols were gradually higher, and that of lathosterol lower from VLDL to HDL. Atorvastatin reduced LDL cholesterol by approximately 50%, decreased the absolute cholesterol synthesis and turnover by approximately 40%, but increased significantly the fractional and mass absorption of cholesterol. In accordance with the fecal data, the ratios of the precursor sterols to cholesterol were reduced (-50%), but those of squalene (+48%) and the absorption sterols increased (e.g. 2.6-fold for sitosterol) similarly in each lipoprotein, but progressively from VLDL to HDL. CONCLUSIONS: Effective lowering of LDL cholesterol by large dose of statin is associated with decreased synthesis and turnover of cholesterol and increased fractional and mass absorption of cholesterol. These changes are detectable by noncholesterol sterols in serum and in different lipoprotein fractions.

Ketomäki A, Gylling H, Siimes MA, Vuorio A, Miettinen TA. · Division of Internal Medicine, Department of Medicine, University of Helsinki, Finland. · Pediatr Res. · Pubmed #12612218 No free full text.

Abstract: Squalene and noncholesterol sterols, e.g. lathosterol and plant sterols, the respective markers of cholesterol synthesis and absorption, are transported with cholesterol in serum lipoproteins. Their concentrations and ratios to cholesterol in serum and lipoproteins have not been carefully compared, especially in children and in marked hypercholesterolemia. Thus, we measured these variables with gas-liquid chromatography in 18 children with and 29 without familial hypercholesterolemia, all aged 5-17 y. Concentrations of most noncholesterol sterols were higher in serum, LDL, and intermediate density lipoprotein in the children with than those without familial hypercholesterolemia. Despite accumulation of noncholesterol sterols mainly in LDL (75% in familial hypercholesterolemia and 55% in non-familial hypercholesterolemia, p < 0.001), their ratios were mostly similar in serum and lipoproteins of the two groups. The ratios of squalene and lathosterol were higher in VLDL and intermediate density lipoprotein, whereas in LDL that of lathosterol was lower than the respective serum values in both groups. Absorption marker sterol ratios were highest in HDL in both groups. Thus, even though the ratios of noncholesterol sterols to cholesterol in serum reflect, in general, synthesis and absorption of cholesterol, their ratios in different lipoproteins could give additional information of cholesterol metabolism.

Gylling H, Miettinen TA. · Department of Clinical Nutrition, University of Kuopio, and Kuopio University Hospital, Kuopio, Finland. · J Lipid Res. · Pubmed #12235179 links to  free full text

Abstract: Heredity of cholesterol absorption and synthesis was studied in siblings of hypercholesterolemic probands with low and high serum cholestanol to cholesterol ratio (assumed to indicate low and high absorption of cholesterol, respectively). Cholesterol synthesis was assayed with sterol balance technique and measuring serum cholesterol precursor to cholesterol ratios (synthesis markers of cholesterol), and cholesterol absorption with measuring dietary cholesterol absorption percentage and serum plant sterol and cholestanol to cholesterol ratios (absorption markers of cholesterol). In the siblings of the low absorption families, cholesterol absorption percentage and ratios of absorption markers were significantly lower, and cholesterol and bile acid synthesis, cholesterol turnover, fecal steroids and ratios of synthesis markers significantly higher than in the siblings of the high absorption families. The ratios of absorption and synthesis markers were inversely interrelated, and they were correlated with cholesterol absorption and synthesis in the siblings. In addition, low absorption was associated with high body mass index, low HDL cholesterol, and serum sex hormone binding globulin levels, suggesting that low absorption was associated with metabolic syndrome. Intrafamily correlations were significant for serum synthesis markers, cholestanol, triglycerides, and blood glucose level. In conclusion, cholesterol absorption efficiency and synthesis are partly inherited phenomena, and they can be predicted by the ratios of non-cholesterol sterols to cholesterol in serum.