Hyperlipidemias: Lütjohann D

Hovenkamp E, Demonty I, Plat J, Lütjohann D, Mensink RP, Trautwein EA. · Unilever Food and Health Research Institute, 3130 AC Vlaardingen, The Netherlands. · Prog Lipid Res. · Pubmed #18022398 No free full text.

Abstract: The cholesterol-lowering effect of phytosterols has been extensively studied, and consumption of phytosterols is among the recommendations to lower LDL-cholesterol concentrations. Due to their structural similarity with cholesterol, phytosterols may undergo oxidative processes comparable to those involved in cholesterol oxidation. Consumption of phytosterols could therefore lead to increased systemic concentrations of oxidized phytosterols (oxyphytosterols) via increased dietary intake or in vivo formation from non-oxidized phytosterols. While the biological effects of oxidized cholesterol (oxycholesterol) have been well studied, the amount of biological research on oxyphytosterols is scarce. Most reports on oxyphytosterols cover their quantitative analysis. Whether oxyphytosterols may play similar biological roles as compared to oxycholesterol has not been fully elucidated. The usual perception about oxyphytosterols is that these components present a concern in terms of food quality and health. This perception originates from the parallel that is made with oxycholesterol. Yet, in line with results for oxycholesterol, recent data suggest that oxyphytosterols--depending on the type of oxidation product--may also have beneficial biological properties. Therefore, the objective of this review is to summarise the current understanding of the biological effects, next to identifying future research needs that will help to clarify the possible impact of oxyphytosterols on human health.

von Bergmann K, Sudhop T, Lütjohann D. · Department of Clinical Pharmacology, University of Bonn, Bonn, Germany. · Am J Cardiol. · Pubmed #15992510 No free full text.

Abstract: The recent discovery of transporters in the intestinal mucosa and the canalicular membrane has given new insights into the regulation of intestinal absorption as well as the biliary output of cholesterol and plant sterols. The 2 adenosine triphosphate (ATP)-binding cassette (ABC) half-transporters ABCG5 and ABCG8 are expressed in the mucosa cells and the canalicular membrane, and they resecrete sterols, especially absorbed plant sterols, back into the intestinal lumen and from the liver into bile. Defects of either of these cotransporters lead to the rare inherited disease of phytosterolemia, which is clinically defined by hyperabsorption and diminished biliary excretion of plant sterols. Furthermore, it has been recently demonstrated that the Niemann-Pick C1-Like 1 (NPC1L1) transporter is most likely responsible for the transport of cholesterol and plant sterols from the brush border membrane into the intestinal mucosa. Ezetimibe interferes with NPC1L1, reducing the intestinal uptake of cholesterol and plant sterols. These new findings contribute to our understanding of cholesterol and plant sterol concentrations in serum, and the effect of dietary and drug intervention to reduce serum concentrations of sterols.

Thuluva SC, Igel M, Giesa U, Lütjohann D, Sudhop T, von Bergmann K. · Department of Clinical Pharmacology, University of Bonn, Germany. · Int J Clin Pharmacol Ther. · Pubmed #16035372 No free full text.

Abstract: OBJECTIVE: Plant sterol/stanol margarines are recommended as a lipid-lowering dietary supplement in the treatment of hypercholesterolemia. Parameters predicting the individual cholesterol-lowering effect have not been elucidated so far. Therefore, we investigated the responsiveness to sitostanol-supplemented margarine in a specially selected population. METHODS AND RESULTS: From a total number of 137 male subjects with hypercholesterolemia, eight subjects with the lowest and eight subjects with the highest ratios of lathosterol to campesterol in serum were included in the study. They received 1 g sitostanol-supplemented margarine b.i.d. for four weeks. Serum lipoproteins, the cholesterol precursor lathosterol, the plant sterols campesterol and sitosterol were measured. Subjects with a low ratio of lathosterol to campesterol had a significant decrease of serum total cholesterol (-14.2%; p < 0.01) and LDL cholesterol (-13.8%; p < 0.01; responder). In subjects with a high ratio there was no significant change in total cholesterol and LDL cholesterol (2.2 and 4.3%; non-responder). CONCLUSION: The ratio of serum lathosterol to campesterol predicts the reduction of total cholesterol and LDL cholesterol during administration of sitostanol-supplemented margarine in patients with mild hypercholesterolemia.

Päivä H, Thelen KM, Van Coster R, Smet J, De Paepe B, Mattila KM, Laakso J, Lehtimäki T, von Bergmann K, Lütjohann D, Laaksonen R. · Department of Internal Medicine, University Hospital of Tampere, Finland. · Clin Pharmacol Ther. · Pubmed #16003294 No free full text.

Abstract: BACKGROUND: Myopathy, probably caused by 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibition in skeletal muscle, rarely occurs in patients taking statins. This study was designed to assess the effect of high-dose statin treatment on cholesterol and ubiquinone metabolism and mitochondrial function in human skeletal muscle. METHODS: Forty-eight patients with hypercholesterolemia (33 men and 15 women) were randomly assigned to receive 80 mg/d of simvastatin (n = 16), 40 mg/d of atorvastatin (n = 16), or placebo (n = 16) for 8 weeks. Plasma samples and muscle biopsy specimens were obtained at baseline and at the end of the follow-up. RESULTS: The ratio of plasma lathosterol to cholesterol, a marker of endogenous cholesterol synthesis, decreased significantly by 66% in both statin groups. Muscle campesterol concentrations increased from 21.1 +/- 7.1 nmol/g to 41.2 +/- 27.0 nmol/g in the simvastatin group and from 22.6 +/- 8.6 nmol/g to 40.0 +/- 18.7 nmol/g in the atorvastatin group (P = .005, repeated-measurements ANOVA). The muscle ubiquinone concentration was reduced significantly from 39.7 +/- 13.6 nmol/g to 26.4 +/- 7.9 nmol/g (P = .031, repeated-measurements ANOVA) in the simvastatin group, but no reduction was observed in the atorvastatin or placebo group. Respiratory chain enzyme activities were assessed in 6 patients taking simvastatin with markedly reduced muscle ubiquinone and in matched subjects selected from the atorvastatin (n = 6) and placebo (n = 6) groups. Respiratory chain enzyme and citrate synthase activities were reduced in the patients taking simvastatin. CONCLUSIONS: High-dose statin treatment leads to changes in the skeletal muscle sterol metabolism. Furthermore, aggressive statin treatment may affect mitochondrial volume.

Sudhop T, Lütjohann D, Kodal A, Igel M, Tribble DL, Shah S, Perevozskaya I, von Bergmann K. · Department of Clinical Pharmacology, University of Bonn, Germany. · Circulation. · Pubmed #12370217 links to  free full text

Abstract: BACKGROUND: Ezetimibe has been shown to inhibit cholesterol absorption in animal models, but studies on cholesterol absorption in humans have not been performed thus far. METHODS AND RESULTS: The effect of ezetimibe (10 mg/d) on cholesterol absorption and synthesis, sterol excretion, and plasma concentrations of cholesterol and noncholesterol sterols was investigated in a randomized, double-blind, placebo-controlled, crossover study in 18 patients with mild to moderate hypercholesterolemia. Treatment periods lasted 2 weeks with an intervening 2-week washout period. Fractional cholesterol absorption rates averaged 49.8+/-13.8% on placebo and 22.7+/-25.8% on ezetimibe, indicating a reduction of 54% (geometric mean ratio; P< 0.001). Cholesterol synthesis increased by 89% from 931+/-1027 mg/d on placebo to 1763+/-1098 mg/d on ezetimibe (P<0.001), while the ratio of lathosterol-to-cholesterol, an indirect marker of cholesterol synthesis, was increased by 72% (P<0.001). Bile acid synthesis was insignificantly increased (placebo: 264+/-209 mg/d, ezetimibe: 308+/-184 mg/d; P=0.068). Mean percent changes from baseline for LDL and total cholesterol after ezetimibe treatment were -20.4% and -15.1%, respectively (P<0.001 for both), whereas campesterol and sitosterol were decreased by -48% and - 41%, respectively. CONCLUSION: In humans, ezetimibe inhibits cholesterol absorption and promotes a compensatory increase of cholesterol synthesis, followed by clinically relevant reductions in LDL and total cholesterol concentrations. Ezetimibe also reduces plasma concentrations of the noncholesterol sterols sitosterol and campesterol, suggesting an effect on the absorption of these compounds as well.

Locatelli S, Lütjohann D, Schmidt HH, Otto C, Beisiegel U, von Bergmann K. · Department of Clinical Pharmacology, Universitätsklinikum, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany. · Arch Neurol. · Pubmed #11843691 links to  free full text

Abstract: BACKGROUND: Previous studies have shown that patients with early onset of Alzheimer disease and vascular dementia have higher levels of circulating brain-derived 24S-hydroxycholesterol (cerebrosterol).Two recent epidemiological studies indicated that treatment with inhibitors of cholesterol synthesis (statins) reduces the incidence of Alzheimer disease. OBJECTIVE: To test the hypothesis that treatment with high-dosage simvastatin reduces circulating levels of 24S-hydroxycholesterol. DESIGN: Prospective, 24-week treatment trial for lowering of cholesterol levels. We conducted assessments at baseline, week 6, and week 24. SETTING: An academic outpatient clinical study. PATIENTS: Eighteen patients who met the criteria for hypercholesterolemia. INTERVENTION: Treatment with 80 mg/d of simvastatin at night. MAIN OUTCOME MEASURES: Plasma lipoprotein levels were measured enzymatically; lathosterol, by means of gas chromatography; and 24S-hydroxycholesterol, by means of gas chromatography-mass spectrometry. RESULTS: Simvastatin reduced total plasma cholesterol levels by 36% and 35% after 6 and 24 weeks, respectively (P<.001). Lathosterol levels were reduced by 74% and 72%, respectively, and the ratio of lathosterol to cholesterol, an indicator of whole-body cholesterol synthesis, was reduced by 60% and 61%, respectively (P<.001). Plasma 24S-hydroxycholesterol levels were lowered by 45% and 53%, respectively (P<.001). The ratio of 24S-hydroxycholesterol to cholesterol also decreased significantly (-12% [P=.01] and -23% [P<.002], respectively). The further reduction of 24S-hydroxycholesterol levels and its ratio to cholesterol from weeks 6 to 24 was also significant (P=.02 for both). CONCLUSIONS: The greater reduction of plasma concentrations of 24S-hydroxycholesterol compared with cholesterol indicates that simvastatin in a dosage of 80 mg/d reduces cholesterol turnover in the brain. The present results might describe a possible mechanism of how long-term treatment with statins could reduce the incidence of Alzheimer disease.

Schiepers OJ, de Groot RH, van Boxtel MP, Jolles J, de Jong A, Lütjohann D, Plat J, Mensink RP. · School for Mental Health and Neuroscience, Department of Psychiatry and Neuropsychology, Maastricht University, 6200 MD Maastricht, The Netherlands. · J Nutr. · Pubmed #19458031 No free full text.

Abstract: Recent animal and human studies have shown that plant sterols and stanols, which are used as functional food ingredients to lower increased LDL cholesterol concentrations, pass the blood-brain barrier. Whether this affects neurocognitive functioning and mental well-being in humans has, to our knowledge, never been investigated. The aim of the present study was therefore to examine the effects of long-term plant sterol or stanol consumption on neurocognitive functioning and mood in a randomized, double-blind, placebo-controlled dietary intervention trial. To this end, hypercholesterolemic individuals, aged 43-69 y, receiving stable statin treatment were randomly assigned to an 85-wk supplementation with margarines enriched with plant sterol esters (2.5 g/d), plant stanol esters (2.5 g/d), or placebo. At baseline and at the end of the intervention period, all participants underwent a cognitive assessment. In addition, subjective cognitive functioning and mood were assessed by means of questionnaires (Cognitive Failure Questionnaire and depression subscale of the Symptom Checklist 90, respectively). Long-term supplementation with plant sterol or stanol esters did not affect cognitive performance (memory, simple information processing speed, complex information processing speed, Letter-Digit Substitution test performance), subjective cognitive functioning, or mood. In conclusion, the present results indicate that long-term use of plant sterols or stanols at recommended intakes of 2.5 g/d does not affect neurocognitive functioning or mood in hypercholesterolemic individuals receiving statin treatment.

de Jong A, Plat J, Lütjohann D, Mensink RP. · Department of Human Biology, Maastricht University, Maastricht, The Netherlands. · Br J Nutr. · Pubmed #18846701 No free full text.

Abstract: Consumption of plant sterol- or stanol-enriched margarines by statin users results in an additional LDL-cholesterol reduction of approximately 10 %, which may be larger than the average decrease of 3-7 % achieved by doubling the statin dose. However, whether this effect persists in the long term is not known. Therefore, we examined in patients already on stable statin treatment the effects of 85 weeks of plant sterol and stanol ester consumption on the serum lipoprotein profile, cholesterol metabolism, and bile acid synthesis. For this, a double-blind randomised trial was designed in which fifty-four patients consumed a control margarine with no added plant sterols or stanols for 5 weeks (run-in period). For the next 85 weeks, seventeen subjects continued with the control margarine and the other two groups with either a plant sterol (n 18) or plant stanol (n 19) (2.5 g/d each) ester-enriched margarine. Blood was sampled at the end of the run-in period and every 20 weeks during the intervention period. Compared with the control group, plant sterol and stanol ester consumption reduced LDL-cholesterol by 0.28 mmol/l (or 8.7 %; P = 0.08) and 0.42 mmol/l (13.1 %; P = 0.006) respectively after 85 weeks. No effects were found on plasma concentrations of oxysterols or 7 alpha-hydroxy-4-cholesten-3-one, a bile acid synthesis marker. We conclude that long-term consumption of both plant sterol and stanol esters effectively lowered LDL-cholesterol concentrations in statin users.

Lütjohann D, von Bergmann K, Sirah W, Macdonell G, Johnson-Levonas AO, Shah A, Lin J, Sapre A, Musliner T. · Department of Clinical Pharmacology, University of Bonn, Bonn, Germany. · Int J Clin Pract. · Pubmed #18822021 No free full text.

Abstract: OBJECTIVE: To assess the long-term efficacy and safety profile of ezetimibe 10 mg/day in patients with homozygous sitosterolemia. METHODS: This was an extension of a multi-centre, randomised, double-blind, placebo-controlled base study in which patients with homozygous sitosterolemia and plasma sitosterol concentrations > 5 mg/dl were randomised 4 : 1 to ezetimibe 10 mg/day (n = 30) or placebo (n = 7) for 8 weeks. Patients who successfully completed the base study with > 80% compliance to study medication were eligible to enter two, successive, 1-year extension studies in which ezetimibe 10 mg/day was administered in an open-label manner. Patients remained on their current treatment regimen (e.g. bile salt-binding resins, statins and low-sterol diet) during the base and extension studies. Patients had to be off ezetimibe therapy for > or = 4 weeks prior to entering the first extension. Efficacy and safety/tolerability parameters were evaluated every 12 and 26 weeks in the first and second years respectively. The primary efficacy end-point was mean percentage change in plasma sitosterol from baseline to study end for the cohort of patients (n = 21) who successfully completed the second extension study. RESULTS: Treatment with ezetimibe 10 mg/day led to significant mean percentage reductions from baseline in plasma concentrations of sitosterol (-43.9%; p < 0.001), campesterol (-50.8%; p < 0.001), low-density lipoprotein (LDL) sterols (-13.1%; p < 0.050), total sterols (-10.3%; p < 0.050) and apolipoprotein (apo) B (-10.1%; p < 0.050). No significant changes from baseline were observed for lathosterol, high-density lipoprotein sterol, triglycerides or apo A-1. Maximal reductions in sitosterol and campesterol occurred within the first 52 weeks of treatment and were sustained for the duration of the study. For LDL sterol, total sterols and apo B, maximal reductions were achieved early (by weeks 4 or 16) and waned slightly through the remainder of the study. Overall ezetimibe 10 mg was well tolerated. CONCLUSION: In patients with homozygous sitoserolemia, long-term treatment with ezetimibe 10 mg/day for 2 years was effective in reducing plasma plant sterol concentrations with an overall favourable safety and tolerability profile.

Wouters K, van Gorp PJ, Bieghs V, Gijbels MJ, Duimel H, Lütjohann D, Kerksiek A, van Kruchten R, Maeda N, Staels B, van Bilsen M, Shiri-Sverdlov R, Hofker MH. · Department of Molecular Genetics, Physiology and Electron Microscopy Unit, Nutrition and Toxicology Research and Cardiovascular Research, Institutes of Maastricht University, Maastricht, The Netherlands. · Hepatology. · Pubmed #18666236 No free full text.

Abstract: Nonalcoholic steatohepatitis (NASH) involves liver lipid accumulation (steatosis) combined with hepatic inflammation. The transition towards hepatic inflammation represents a key step in pathogenesis, because it will set the stage for further liver damage, culminating in hepatic fibrosis, cirrhosis, and liver cancer. The actual risk factors that drive hepatic inflammation during the progression to NASH remain largely unknown. The role of steatosis and dietary cholesterol in the etiology of diet-induced NASH was investigated using hyperlipidemic mouse models fed a Western diet. Livers of male and female hyperlipidemic (low-density lipoprotein receptor-deficient [ldlr(-/-)] and apolipoprotein E2 knock-in [APOE2ki]) mouse models were compared with livers of normolipidemic wild-type (WT) C57BL/6J mice after short-term feeding with a high-fat diet with cholesterol (HFC) and without cholesterol. Whereas WT mice displayed only steatosis after a short-term HFC diet, female ldlr(-/-) and APOE2ki mice showed steatosis with severe inflammation characterized by infiltration of macrophages and increased nuclear factor kappaB (NF-kappaB) signaling. Remarkably, male ldlr(-/-) and APOE2ki mice developed severe hepatic inflammation in the absence of steatosis after 7 days on an HFC diet compared with WT animals. An HFC diet induced bloated, "foamy" Kupffer cells in male and female ldlr(-/-) and APOE2ki mice. Hepatic inflammation was found to be linked to increased plasma very low-density lipoprotein (VLDL) cholesterol levels. Omitting cholesterol from the HFC diet lowered plasma VLDL cholesterol and prevented the development of inflammation and hepatic foam cells. CONCLUSION: These findings indicate that dietary cholesterol, possibly in the form of modified plasma lipoproteins, is an important risk factor for the progression to hepatic inflammation in diet-induced NASH.

van den Kommer TN, Dik MG, Comijs HC, Fassbender K, Lütjohann D, Jonker C. · Longitudinal Aging Study Amsterdam, EMGO Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands. · Neurobiol Aging. · Pubmed #17888546 No free full text.

Abstract: In this prospective study we examined whether total cholesterol and the oxysterols 24S- and 27-hydroxycholesterol were related to cognitive performance and rate of cognitive decline in elderly, and whether these associations were modified by ApoE epsilon 4. Data were collected during 6 years of follow-up as part of the Longitudinal Aging Study Amsterdam (N=1181, age >or=65 years), and analyzed using generalized estimating equations. Cognitive performance was measured with the mini-mental state examination (general cognition), the auditory verbal learning test (memory) and the coding task (information processing speed). Lower cholesterol at baseline was negatively associated with both general cognition (p=.012) and information processing speed (p=.045). ApoE modified the association between cholesterol and cognitive decline, and the association between the ratio of 27-hydroxycholesterol to cholesterol and cognitive functioning. In ApoE epsilon 4 carriers, lower cholesterol was related to a higher rate of decline on information processing speed (p=.006), and a higher ratio of 27-hydroxycholesterol to cholesterol was related to a lower level of general performance (p=.002) and memory functioning (p=.045). The results implicate that lower total cholesterol may be considered as a frailty marker, predictive of lower cognitive functioning in elderly.

Fricke CB, Schrøder M, Poulsen M, von Bergmann K, Wester I, Knudsen I, Mortensen A, Lütjohann D. · Department of Clinical Pharmacology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany. · Br J Nutr. · Pubmed #17537294 No free full text.

Abstract: Foods containing plant sterol or stanol esters can be beneficial in lowering LDL-cholesterol concentration, a major risk factor for CVD. The present study examined whether high dietary intake of rapeseed oil (RSO) derived plant sterol and stanol esters is associated with increased levels of these components in brain tissue of homozygous and heterozygous Watanabe rabbits, an animal model for familial hypercholesterolemia. Homozygous animals received either a standard diet, RSO stanol or RSO sterol ester while heterozygous animals were additionally fed with 2 g cholesterol/kg to the respective diet form for 120 d (n 9 for each group). Concentrations of cholesterol, its precursor lathosterol, plant sterols and stanols in brain and additionally in liver and plasma were determined by highly sensitive GC-MS. High-dose intake of RSO derived plant sterols and stanols resulted in increased levels of these components in plasma and liver. In brain a limited uptake of plant sterols and stanols was proven, indicating that these compounds passed the blood-brain barrier and may be retained in the brain tissue of Watanabe rabbits. Plant stanol ester feeding lowered plant sterol levels in brain, liver, and plasma. Cholesterol synthesis in brain, indicated by lathosterol, a local surrogate cholesterol synthesis marker, does not seem to be affected by plant sterol or stanol ester feeding. We conclude that high dose intake of plant sterol and stanol esters in Watanabe rabbits results in elevated concentrations of these components not only in the periphery but also in the central nervous system.

Luomala M, Päivä H, Thelen K, Laaksonen R, Saarela M, Mattila K, Lütjohann D, Lehtimaki T. · Laboratory of Atherosclerosis Genetics, Centre for Laboratory Medicine, Tampere University Hospital, Finn-Medi 5 7th floor, P.O. Box 2000, 33521, Tampere, Finland. · Acta Cardiol. · Pubmed #17536607 No free full text.

Abstract: OBJECTIVE: Atherosclerotic lesions are characterized by an accumulation of inflammatory cells and lipids. Osteopontin (OPN) is a cell-binding phosphoprotein, and it seems to promote the development of atherosclerosis. The purpose of our study was to find out whether plasma levels of OPN are associated with cholesterol metabolites in plasma or tissues. METHODS AND RESULTS: Forty-three normal or mildly hypercholesterolaemic subjects, aged 31 to 69, were studied.The plasma level of OPN correlated negatively with muscle lathosterol (r = -0.52, P < 0.0001) and with the muscle lathosterol to muscle cholesterol ratio (r = -0.48, P = 0.001). Lathosterol concentrations in muscle (P = 0.003) and in relation to cholesterol (P = 0.005) were also significantly different among the OPN tertiles. OPN correlated negatively and significantly with muscle lathosterol in men (r = -0.58, P = 0.001, n = 29) but not in women (r = -0.21, P = 0.48, n = 14). Correspondingly, it also correlated negatively and significantly with the muscle lathosterol to muscle cholesterol ratio (r = -0.60, P = 0.001) in men but not in women (r = -0.13, P = 0.65). Plasma levels of OPN had a non-significant inverse correlation with plasma lathosterol and the plasma lathosterol to plasma cholesterol ratio. Plasma OPN concentrations were not related to plant sterols, cholesterol and 27-hydroxycholesterol. CONCLUSIONS: Tissue markers of cholesterol synthesis were related to plasma OPN, particularly in men.This suggests that there is interplay between OPN and cholesterol metabolism in human cells.

Luomala M, Päivä H, Laaksonen R, Thelen K, Lütjohann D, Peltonen N, Lehtimäki T. · Laboratory of Atherosclerosis Genetics, Centre for Laboratory Medicine, Department of Clinical Chemistry, Tampere and Medical School, Tampere University HospitalUniversity of Tampere, P.O. Box 2000, FI-33521, Finland. · Scand Cardiovasc J. · Pubmed #17012138 No free full text.

Abstract: OBJECTIVES: CD40 is a marker of immunological activation and is expressed in the atherosclerotic lesions. We studied whether CD40 and cholesterol synthesis pathways are associated with each other. DESIGN: Forty-three subjects were randomly assigned to receive either simvastatin (n = 14), atorvastatin (n = 15), or placebo (n = 14) for eight weeks. Plasma samples were obtained before and at the end of the follow-up. sCD40 levels were measured in duplicate using an enzyme-linked immunosorbent assay. Cholesterol, its precursor lathosterol, the plant sterols campesterol and sitosterol as well as 27-hydroxycholesterol were quantified by gas-liquid chromatography-mass spectrometry. RESULTS: sCD40 was inversely correlated with the lathosterol to cholesterol ratio (r = - 0.47, p = 0.002), an indicator of cholesterol synthesis rate, as well as apolipoprotein A-I (r = - 0.38, p = 0.01) in addition to being directly correlated with 27-hydroxycholesterol (r = 0.40, p = 0.008). In multivariate linear regression analysis these three predictors explained 37% of the total variability of sCD40 levels. Simvastatin or atorvastatin treatment had no significant effect on sCD40 levels. CONCLUSION: These results indirectly suggest that sCD40 concentrations are related to cellular cholesterol levels. This may be a novel indication for the relationship between immunological processes and cholesterol metabolism.

Thelen KM, Laaksonen R, Päivä H, Lehtimäki T, Lütjohann D. · Department of Clinical Pharmacology, University of Bonn, Sigmund-Freud-Str. 25, D-53105 Bonn, Germany. · J Clin Pharmacol. · Pubmed #16809807 No free full text.

Abstract: Statins inhibit endogenous cholesterol synthesis, up-regulate low-density lipoprotein (LDL) receptor expression in mammalian liver cells, and thus decrease circulating LDL-cholesterol concentrations. As cholesterol seems to play a role in the development of neurodegenerative diseases, it is of interest to evaluate the effect of high dosages of statins (eg, atorvastatin or simvastatin) on brain cholesterol metabolism. Plasma samples from 44 participants (aged 30-69 years, 16 men and 18 women) of an earlier randomized, placebo-controlled, double-blind trial, who took 40 mg atorvastatin or 80 mg simvastatin daily for 2 months, were used to analyze total cholesterol, its precursor lathosterol, and its metabolites 24(S)-hydroxycholesterol and 27-hydroxycholesterol. Despite a significant decrease in absolute plasma concentrations of oxysterols, total cholesterol, and its endogenous synthesis rate, indicated by a decreased ratio of lathosterol to cholesterol, the plasma 24(S)-hydroxycholesterol to cholesterol ratio, a surrogate marker of brain cholesterol homeostasis, remained unchanged. Short-term high-dose atorvastatin and simvastatin treatment does not seem to influence brain cholesterol metabolism in patients with moderately elevated plasma cholesterol levels.

Laaksonen R, Thelen KM, Päivä H, Matinheikki J, Vesalainen R, Janatuinen T, Knuuti J, Rontu R, von Bergmann K, Lütjohann D, Lehtimäki T. · Department of Internal Medicine, University Hospital of Tampere, Tampere, Finland. · Atherosclerosis. · Pubmed #16005884 No free full text.

Abstract: Sterol regulatory element binding proteins-1 and -2 (SREBPs) are transcription factors controlling lipid homeostasis in human cells. The G-allele carriers of the SREBF-1 gene C-G polymorphism in exon 18c and coding for glycine at the protein level (G952G) have shown to associate more frequently with obesity and type 2 diabetes than the C-allele carriers. However, the C-allele has suggested to be linked to dyslipidemia. Thus, our aim was to study effect of the SREBF-1 gene polymorphism (G952G) on sterol metabolism in man. Ninety-five subjects with moderate hypercholesterolemia participated in this study and 14 homozygous CC carriers of the SREBF-1 (G952G) gene were found. Plasma lathosterol concentration and lathosterol-to-cholesterol ratio, markers of endogenous cholesterol synthesis, were significantly higher in CC homozygous subject compared to others. Similarly muscle cholesterol (p=0.045) and lathosterol (p=0.054) concentrations were elevated in the CC homozygotes supporting the view that endogenous cholesterol synthesis rate is SREBF-1 genotype-dependent.

Lütjohann D, von Bergmann K. · Department of Clinical Pharmacology, University of Bonn, Germany. · Pharmacopsychiatry. · Pubmed #14574622 No free full text.

Abstract: The enzymatic conversion of CNS cholesterol to 24S-hydroxycholesterol, which readily crosses the blood-brain barrier, is the major pathway for brain cholesterol elimination and brain cholesterol homeostasis maintenance. The enzyme mediating this conversion has been characterized at the molecular level (CYP46) and is mainly located in neurons. Like other oxysterols, 24S-hydroxycholesterol is efficiently converted into normal bile acids or excreted in bile in its sulfated and glucuronidated form. Levels of 24S-hydroxycholesterol in the circulation decrease with age in infants and children. In adults, however, the levels appear to be stable. There is accumulating evidence pointing toward a potentially important link between cholesterol, beta-amyloid, and Alzheimer's disease. Concentrations of 24S-hydroxycholesterol in plasma and cerebrospinal fluid (CSF) are significantly higher in Alzheimer's disease and vascular demented patients at early stages of the disease compared to healthy subjects. Variations in genetic background, time of disease onset, and severity of dementia are potential sources of variance. Inhibitors of cholesterol biosynthesis, also termed statins, seem to have a reductive influence on the generation of the amyloid precursor protein, the neuronal secretion of beta-amyloid, and on de novo cholesterol synthesis. Recent epidemiological studies indicate that the prevalence of diagnosed AD and vascular dementia is reduced among people taking statins for a longer period of time. High-dose simvastatin treatment (80 mg/day) in patients with hypercholesterolemia leads to a significant decrease in brain-specific serum 24S-hydroxycholesterol concentrations and indicates a diminished cholesterol metabolism in the brain. CSF levels of cholesterol and lathosterol, a cholesterol precursor considered to be an indicator for cholesterol neogenesis, were significantly decreased in statin-treated subjects compared to non-treated normo- and hypercholesterolemic subjects. Also, CSF concentrations of 24S-hydroxycholesterol were significantly lower in statin-treated patients compared to normocholesterolemic subjects. Treatment with high-dose simvastatin in normocholesterolemic Alzheimer patients for 26 weeks at early stages of the disease results in a significant decrease in Abeta-levels in cerebrospinal fluid. This decrease correlates with the reduction of 24S-hydroxycholesterol.

Schönknecht P, Lütjohann D, Pantel J, Bardenheuer H, Hartmann T, von Bergmann K, Beyreuther K, Schröder J. · Section of Geriatric Psychiatry, Department of Psychiatry, University of Heidelberg, Voss-Strasse 4, 69115, Germany. · Neurosci Lett. · Pubmed #11983301 No free full text.

Abstract: Experiments in cell cultures indicate that accumulation of cholesterol in hippocampal neurons results in an accelerated cleavage of amyloid precursor protein into amyloidogenic components. To be eliminated from the brain, cholesterol is converted to 24S-hydroxycholesterol which may reflect cerebral cholesterol turnover. We investigated cerebrospinal fluid (CSF) concentrations of 24S-hydroxycholesterol in a group of 14 Alzheimer's disease (AD) patients and ten healthy controls without any cognitive deficits or psychiatric or neurological disorders. To exclude potential effects of circulating plasma cholesterol on CSF 24S-hydroxycholesterol levels, only patients and controls with cholesterol levels in the normal range of 150-230 mg/dl were included. We found significantly elevated 24S-hydroxycholesterol CSF but not plasma levels in AD patients compared with healthy controls. Our results demonstrate that CSF 24S-hydroxycholesterol is increased in AD. This effect does not seem to be triggered by plasma cholesterol levels since the latter did not significantly differ between groups.