scholarly journals The Chylomicron: Relationship to Atherosclerosis

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Gerald H. Tomkin ◽  
Daphne Owens
Keyword(s):  
Cholesterol Synthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Structural Protein ◽  
Chylomicron Particle ◽  
Niemann Pick ◽  
Chylomicron Formation ◽  
The Relationship ◽  
Ldl Composition

The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20% andusually <10%. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis.

scholarly journals SAT-456 Reduced Cholesterol Absorption and Synthesis Markers in Patients with Hyperthyroidism Due to Graves’ Disease

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Tomoko Nagamine ◽  
Kyoko Inagaki ◽  
Shunsuke Kobayashi ◽  
Yuki Shuto ◽  
Mototsugu Nagao ◽  
...  
Keyword(s):  
Cholesterol Synthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Graves Disease ◽  
Euthyroid State ◽  
Niemann Pick ◽  
Coa Reductase

Abstract Background:Thyroid hormones have been reported to promote cell-surface expression of low-density lipoprotein receptor (LDL-R), and also increase mRNA expression of HMG-CoA reductase at the same time. Since LDL cholesterol (LDL-C) uptake via LDL-R is relatively superior to cholesterol synthesis in hyperthyroidism, plasma LDL-C levels can be lower as compared to euthyroid state. Conversely, hypothyroidism can increase plasma LDL-C levels because cholesterol absorption via Niemann-Pick C1-like 1 has been suggested to increase in hypothyroidism. However, there have been no reports about changes of cholesterol absorption and synthesis markers by the treatment of hyperthyroidism in patients with Graves’ disease. Patients and method: We collected plasma samples from patients with hyperthyroidism, who were diagnosed as Graves’ disease (n=17, M/F: 4/13, age: 24-70 years old). Thyroid hormones, general lipid profiles (Total cholesterol: TC, LDL-C, high-density lipoprotein cholesterol: HDL-C and triglyceride: TG), apolipoproteins, markers of cholesterol synthesis (lathosterol) and absorption (campesterol, sitosterol, cholestanol), lipoprotein lipase (LPL), and proprotein convertase subtilisin/kexin type 9 (PCSK9) were analyzed before treatment, and at euthyroid state (eu), 3 and 6 months after attaining euthyroid state (eu-3M and eu-6M). Result: It took 159.2±108.6 days to attain euthyroid state by the thiamazole treatment. TC, LDL-C and HDL-C levels were increased at eu (TC, 144.5±26.7 to 225.0±61.6; LDL-C, 77.8±20.9 to 138.9±43.9; HDL-C, 49.7±12.6 to 67.9±20.0 mg/dL: P&lt;0.0001 vs before treatment, respectively). Such changes remained at eu-3M and eu-6M. TG was not changed at eu, but significantly increased at eu-6M (85.0±49.1 to 113.7±60.8 mg/dL, P=0.02). Cholesterol absorption markers were increased at eu, eu-3M and eu-6M (e.g. campesterol, 2.6±1.2 to 4.9±2.3; sitosterol, 1.5±0.6 to 2.9±1.4; cholestanol, 1.9±0.6 to 3.2±1.1 μg/mL: P&lt;0.0001, eu vs before treatment, respectively). Cholesterol synthesis marker was increased at eu, eu-3M and eu-6M (e.g. lathosterol, 1.8±0.7 to 2.3±0.9 μg/mL: P=0.005, eu vs before treatment). Both LPL and PCSK9 were also increased at eu, eu-3M and eu-6M. Conclusion: These data suggest that both cholesterol absorption and synthesis are downregulated in patients with hyperthyroidism due to Graves’ disease and can be restored by attaining euthyroid state. In turn, LDL-C and TG levels should be carefully monitored during the treatment of Graves’ disease because hyperlipidemia could emerge in euthyroid state.

Absorption and metabolism of cholesterol in familial hypercholesterolemia

1989 ◽  
Vol 76 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Helena Gylling ◽  
Tatu A. Miettinen
Keyword(s):  
Cholesterol Synthesis ◽  
Familial Hypercholesterolaemia ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Dietary Cholesterol ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Lipoprotein Cholesterol ◽  
Low Density ◽  
Cholesterol Intake

1. The present study investigated the role of intestinal cholesterol absorption in the regulation of cholesterol metabolism and serum lipoprotein levels in 22 patients with heterozygous familial hypercholesterolaemia on low to normal cholesterol intake. 2. The results showed that the higher the dietary cholesterol absorption, the lower was the overall synthesis of cholesterol. Efficient cholesterol absorption actually reduced the elimination of cholesterol as faecal neutral sterols but not consistently as bile acids. 3. In multifactorial analysis, body mass index and dietary plant sterols were negatively associated with cholesterol absorption, but were unrelated to cholesterol synthesis. 4. Fractional cholesterol absorption was related only to the serum very-low-density triacylglycerol level. It was not associated with the total or low-density lipoprotein cholesterol levels. On the other hand, cholesterol synthesis was significantly associated with the serum concentrations of very-low-density lipoprotein and intermediate-density lipoprotein cholesterol and triacylglycerols, and with those of low-density lipoprotein triacylglycerols. 5. In conclusion, dietary cholesterol absorption is an essential regulator of cholesterol homoeostasis in familial hypercholesterolaemia, even in patients on low cholesterol intake.

Association between non-responsiveness to plant sterol intervention and polymorphisms in cholesterol metabolism genes: a case-control study

2008 ◽  
Vol 33 (4) ◽  
pp. 728-734 ◽  
Author(s):  
Iwona Rudkowska ◽  
Suhad S. AbuMweis ◽  
Catherine Nicolle ◽  
Peter J.H. Jones
Keyword(s):  
Plant Sterol ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Individual Variability ◽  
Nucleotide Polymorphisms ◽  
Control Phase ◽  
Individual Variations ◽  
Niemann Pick

Plant sterol (PS) consumption decreases low-density lipoprotein cholesterol (LDL-C) levels; however, high variability of responsiveness of lipid levels to PS intervention has been observed. We hypothesized that common single-nucleotide polymorphisms (SNPs) in the genes for the ATP binding cassette proteins G5 (ABCG5) and G8 (ABCG8), Niemann-Pick C1-like 1 (NPC1L1), or other proteins of the cholesterol pathway, would underline inter-individual variations in response to PS. Twenty-six hyperlipidemic subjects completed a randomized trial of 3 PS phases and a control phase. Three non-responders were identified who failed on 3 consecutive occasions to decrease either total cholesterol or LDL-C level vs. control. It was observed that after 3 PS phases compared with a control phase, cholesterol absorption changed to a lesser degree (–7.7% ± 10.8%) in the non-responders than in the top 3 responders (–22.1% ± 8.8%); however, cholesterol synthesis rates did not differ between sub-groups. No common polymorphisms in ABCG8, ABCG5, or NPC1L1 were demonstrated between the 3 top responders and the non-responders. Yet, 1 non-responsive subject did demonstrate a rare SNP in NPC1L1. Results indicate PS intake did not decrease cholesterol absorption rates to the same degree in certain subjects, possibly clarifying the inter-individual variability in the cholesterol-lowering effect; hence, this work should be expanded.

scholarly journals NPC1L1 Facilitates Sphingomyelin Absorption and Regulates Diet-Induced Production of VLDL/LDL-associated S1P

Nutrients ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2641
Author(s):  
Yoshihide Yamanashi ◽  
Tappei Takada ◽  
Hideaki Yamamoto ◽  
Hiroshi Suzuki
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
In Vivo Studies ◽  
Lipid Mediator ◽  
Low Density ◽  
Dependent Manner ◽  
Niemann Pick

Niemann-Pick C1-Like 1 (NPC1L1) is a cholesterol importer and target of ezetimibe, a cholesterol absorption inhibitor used clinically for dyslipidemia. Recent studies demonstrated that NPC1L1 regulates the intestinal absorption of several fat-soluble nutrients, in addition to cholesterol. The study was conducted to reveal new physiological roles of NPC1L1 by identifying novel dietary substrate(s). Very low-density lipoprotein and low-density lipoprotein (VLDL/LDL) are increased in Western diet (WD)-fed mice in an NPC1L1-dependent manner, so we comprehensively analyzed the NPC1L1-dependent VLDL/LDL components. Apolipoprotein M (apoM), a binding protein of sphingosine-1-phosphate (S1P: a lipid mediator), and S1P were NPC1L1-dependently increased in VLDL/LDL by WD feeding. S1P is metabolized from sphingomyelin (SM) and SM is abundant in WD, so we focused on intestinal SM absorption. In vivo studies with Npc1l1 knockout mice and in vitro studies with NPC1L1-overexpressing cells revealed that SM is a physiological substrate of NPC1L1. These results suggest a scenario in which dietary SM is absorbed by NPC1L1 in the intestine, followed by SM conversion to S1P and, after several steps, S1P is exported into the blood as the apoM-bound form in VLDL/LDL. Our findings provide insight into the functions of NPC1L1 for a better understanding of sphingolipids and S1P homeostasis.

scholarly journals Structures of dimeric human NPC1L1 provide insight into mechanisms for cholesterol absorption

2021 ◽  
Vol 7 (34) ◽  
pp. eabh3997
Author(s):  
Tao Long ◽  
Yang Liu ◽  
Yu Qin ◽  
Russell A. DeBose-Boyd ◽  
Xiaochun Li
Keyword(s):  
Low Density Lipoprotein ◽  
Transmembrane Helix ◽  
Dietary Cholesterol ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Oligomeric State ◽  
Cryo Electron Microscopy ◽  
Niemann Pick ◽  
Circulating Levels ◽  
Insight Into

Polytopic Niemann-Pick C1-like 1 (NPC1L1) plays a major role in intestinal absorption of biliary cholesterol, vitamin E (VE), and vitamin K (VK). The drug ezetimibe inhibits NPC1L1-mediated absorption of cholesterol, lowering of circulating levels of low-density lipoprotein cholesterol. Here, we report cryo–electron microscopy structures of human NPC1L1 (hNPC1L1) bound to either cholesterol or a lipid resembling VE. These findings, together with functional assays, reveal that the same intramolecular channel in hNPC1L1 mediates transport of VE and cholesterol. hNPC1L1 exists primarily as a homodimer; dimerization is mediated by aromatic residues within a region of transmembrane helix 2 that exhibits a horizonal orientation in the membrane. Mutation of tryptophan-347 lies in this region disrupts dimerization and the resultant monomeric NPC1L1 exhibits reduced efficiency of cholesterol uptake. These findings identify the oligomeric state of hNPC1L1 as a target for therapies that inhibit uptake of dietary cholesterol and reduce the incidence of cardiovascular disease.

scholarly journals The Effects of Anthocyanin-Rich Bilberry Extract on Transintestinal Cholesterol Excretion

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2852
Author(s):  
Jimin Hong ◽  
Minji Kim ◽  
Bohkyung Kim
Keyword(s):  
De Novo ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Lipoprotein Receptors ◽  
Expression Of Genes ◽  
Cholesterol Excretion ◽  
Niemann Pick ◽  
Bilberry Extract

Hypercholesterolemia is one of the modifiable and primary risk factors for cardiovascular diseases (CVD). Emerging evidence suggests the stimulation of transintestinal cholesterol excretion (TICE), the nonbiliary cholesterol excretion, using natural products can be an effective way to reduce CVD. Bilberry (Vaccinium myrtillus L.) has been reported to have cardioprotective effects by ameliorating oxidative stress, inflammation, and dyslipidemia. However, the role of bilberry in intestinal cholesterol metabolism is not well understood. To examine the effects of bilberry in intestinal cholesterol metabolism, we measured the genes for cholesterol flux and de novo synthesis in anthocyanin-rich bilberry extract (BE)-treated Caco-2 cells. BE significantly decreased the genes for cholesterol absorption, i.e., Niemann-Pick C1 Like 1 and ATP-binding cassette transporter A1 (ABCA1). In contrast, BE significantly upregulated ABCG8, the apical transporter for cholesterol. There was a significant induction of low-density lipoprotein receptors, with a concomitant increase in cellular uptake of cholesterol in BE-treated cells. The expression of genes for lipogenesis and sirtuins was altered by BE treatment. In the present study, BE altered the genes for cholesterol flux from basolateral to the apical membrane of enterocytes, potentially stimulating TICE. These results support the potential of BE in the prevention of hypercholesterolemia.

scholarly journals The PCSK9 revolution and the potential of PCSK9-based therapies to reduce LDL-cholesterol

2017 ◽  
Vol 2017 (1) ◽  
Author(s):  
Nabil G Seidah
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Absorption ◽  
Cardiovascular Death ◽  
Cardiovascular Complications ◽  
Inherited Disease ◽  
Reductase Inhibitors ◽  
Target Values ◽  
Niemann Pick ◽  
Coa Reductase

[first paragraph of article]A large number of clinical trials over the last 30 years have firmly consolidated the importance of lowering low density lipoprotein cholesterol (LDLc) in the prevention of cardiovascular diseases (CVD) and its associated devastating sequelae. While healthy diets and exercise are highly recommended to lower LDLc levels, in many individuals with high baseline levels of LDLc, this is not sufficient to bring levels down to recommended target values in order to prevent recurrent coronary heart disease and cardiovascular complications. This is especially true for patients at high risk of premature cardiovascular death and disability, including those with familial hypercholesterolaemia (FH). FH is a very common inherited disease – affecting at least 30 million people worldwide, with an overall incidence of 1:200 globally – of whom ≤ 1% have been diagnosed. The advent of HMG-CoA reductase inhibitors, also known as ‘‘statins’’, and their first application to hypercholesterolemic patients over 30 years ago, has revolutionized the treatment of FH patients and resulted in substantial lowering of LDLc. In addition, cholesterol– lowering drugs, such as ‘‘ezetimibe’’ that blocks cholesterol absorption from the gut by inhibiting the Niemann-Pick C1-like 1 (NPC1L1) transporter, have also been successful and a 7-year IMPROVE-IT trial revealed that a ‘‘simvastatin-ezetimibe’’ combination resulted in an incremental lowering of LDLc levels and a modest 2% improved cardiovascular outcomes.3 Therefore, it became clear that additional treatments are needed to substantially decrease LDLc and efficiently protect against CVD. 

scholarly journals The relationship of the serum endocan level with the CHA2DS2-VASc score in patients with paroxysmal atrial fibrillation

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Gökhan Ceyhun
Keyword(s):  
Atrial Fibrillation ◽  
Paroxysmal Atrial Fibrillation ◽  
Stroke Risk ◽  
Low Density Lipoprotein ◽  
Multivariate Logistic Regression Analysis ◽  
Density Lipoprotein ◽  
Roc Curve Analysis ◽  
Reactive Protein ◽  
Relationship Of ◽  
The Relationship

Abstract Background In this study considering the relationship between serum endocan and CHA2DS2-VASc score, we assumed that endocan level could be a new biomarker for stroke risk in patients with paroxysmal atrial fibrillation (PAF). It was examined that endocan could be an alternative to determine the risk of stroke and anticoagulation strategy in patients with PAF. The CHA2DS2-VASc scores were calculated for 192 patients with PAF, and their serum endocan levels were measured. The patients were divided into two groups as those with low to moderate (0-1) and those with high (≥ 2) CHA2DS2-VASc scores, and the endocan levels were compared between these two groups. Results The serum endocan level was significantly higher in the high CHA2DS2-VASc score group (p < 0.001). In the multivariate logistic regression analysis, endocan, C-reactive protein, and low-density lipoprotein were found to be independent determinants of the CHA2DS2-VASc score. The predictive value of endocan was analyzed using the ROC curve analysis, which revealed that endocan predicted a high stroke risk (CHA2DS2-VASc ≥ 2) at 82.5% sensitivity and 71.2% specificity at the cutoff value of 1.342. Conclusion This study indicates that endocan is significantly associated with CHA2DS2-VASc score. We demonstrated that endocan could be a new biomarker for the prediction of a high stroke risk among patients diagnosed with PAF.

Sign in / Sign up

Export Citation Format

Share Document