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Dysregulated Brain Cholesterol Metabolism Is Linked to Neuroinflammation in Huntington's Disease.
González-Guevara, E, Cárdenas, G, Pérez-Severiano, F, Martínez-Lazcano, JC
Movement disorders : official journal of the Movement Disorder Society. 2020;(7):1113-1127
Abstract
Huntington's disease is an autosomal-dominant, neurodegenerative disorder caused by a CAG repeat expansion in exon-1 of the huntingtin gene. Alterations in cholesterol metabolism and distribution have been reported in Huntington's disease, including abnormal interactions between mutant huntingtin and sterol regulatory element-binding proteins, decreased levels of apolipoprotein E/cholesterol/low-density lipoprotein receptor complexes, and alterations in the synthesis of ATP-binding cassette transporter A1. Plasma levels of 24S-hydroxycholestrol, a key intermediary in cholesterol metabolism and a possible marker in neurodegenerative diseases, decreased proportionally to the degree of caudate nucleus atrophy. The interaction of mutant huntingtin with sterol regulatory element-binding proteins is of particular interest given that sterol regulatory element-binding proteins play a dual role: They take part in lipid and cholesterol metabolism, but also in the inflammatory response that induces immune cell migration as well as toxic effects, particularly in astrocytes. This work summarizes current evidence on the metabolic and immune implications of sterol regulatory element-binding protein dysregulation in Huntington's disease, highlighting the potential use of drugs that modulate these alterations. © 2020 International Parkinson and Movement Disorder Society.
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G Protein-Coupled Estrogen Receptor, GPER1, Offers a Novel Target for the Treatment of Digestive Diseases.
DeLeon, C, Wang, DQ, Arnatt, CK
Frontiers in endocrinology. 2020;:578536
Abstract
There are gender differences between men and women in many physiological functions and diseases, which indicates that female sex hormones may be important. Traditionally, estrogen exerts its biological activities by activating two classical nuclear estrogen receptors, ESR1 and ESR2. However, the roles of estrogen in the regulation of physiological functions and the pathogenesis of diseases become more complicated with the identification of the G protein-coupled estrogen receptor (GPER1). Although many GPER1-specific ligands have been developed, the therapeutic mechanisms of exclusively targeting GPER1 are not yet well understood. Translational applications and clinical trial efforts for the identified GPER1 ligands have been focused primarily on the reproductive, cardiovascular, nervous, endocrine, and immune systems. More recently, research found that GPER1 may play an important role in regulating the digestive system. Cholesterol gallstone disease, a major biliary disease, has a higher prevalence in women than in men worldwide. Emerging evidence implies that GPER1 could play an important role, independent of the classical ESR1, in the pathophysiology of cholesterol gallstones in women. This review discusses the complex signaling pathways of three estrogen receptors, highlights the development of GPER1-specific ligands, and summarizes the latest advances in the role of GPER1 in the pathogenesis of gallstone formation.
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Chemical Pathology of Homocysteine VII. Cholesterol, Thioretinaco Ozonide, Mitochondrial Dysfunction, and Prevention of Mortality.
McCully, KS
Annals of clinical and laboratory science. 2019;(4):425-438
Abstract
The purpose of this review is to elucidate how low blood cholesterol promotes mitochondrial dysfunction and mortality by the loss of thioretinaco ozonide from opening of the mitochondrial permeability transition pore (mPTP). Mortality from infections and cancer are both inversely associated with blood cholesterol, as determined by multiple cohort studies from 10 to 30 years earlier. Moreover, low-density lipoprotein (LDL) is inversely related to all-cause and/or cardiovascular mortality, as determined by followup study of elderly cohorts. LDL adheres to and inactivates most microorganisms and their toxins, causing aggregation of LDL and homocysteinylated autoantibodies which obstruct vasa vasorum and produce intimal microabscesses, the vulnerable atherosclerotic plaques. The active site of mitochondrial oxidative phosphorylation and adenosine triphosphate (ATP) biosynthesis is proposed to consist of thioretinaco, a complex of two molecules of thioretinamide with cobalamin, oxidized to the disulfonium thioretinaco ozonide and complexed with oxygen, nicotinamide adenine dinucleotide (NAD+), phosphate, and ATP. Loss of the active site complex from mitochondria results from the opening of the mPTP and from decomposition of the disulfonium active site by electrophilic carcinogens, oncogenic viruses, microbes, and by reactive oxygen radicals from ionizing and non-ionizing radiation. Suppression of innate immunity is caused by the depletion of adenosyl methionine because of increased polyamine biosynthesis, resulting in inhibition of nitric oxide and peroxynitrite biosynthesis. Opening of the mPTP produces a loss of thioretinaco ozonide from mitochondria. This loss impairs ATP biosynthesis and causes the mitochondrial dysfunction observed in carcinogenesis, atherosclerosis, aging and dementia. Cholesterol inhibits the opening of the mPTP by preventing integration of the pro-apoptotic Bcl-2-associated X protein (BAX) in the outer mitochondrial membrane. This inhibition explains how elevated LDL reduces mitochondrial dysfunction by preventing loss of the active site of oxidative phosphorylation from mitochondria.
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Analysis of S100A12 plasma levels in hyperlipidemic subjects with or without familial hypercholesterolemia.
Scicali, R, Di Pino, A, Urbano, F, Ferrara, V, Marchisello, S, Di Mauro, S, Scamporrino, A, Filippello, A, Piro, S, Rabuazzo, AM, et al
Acta diabetologica. 2019;(8):899-906
Abstract
AIMS: Inflammation is a key regulatory process that links hypercholesterolemia and immune mechanisms promoting atherosclerosis. Inflammatory biomarkers may be helpful to better define the atherosclerotic burden in patients with high cholesterol levels such as familial hypercholesterolemia (FH). Our aim was to evaluate the concentration of S100A12 protein in FH patients and its association with pulse wave velocity (PWV). METHODS We measured glucose and lipid profile, S100A12, sRAGE, esRAGE and PWV in 39 patients with a genetically confirmed diagnosis of FH and 39 hypercholesterolemic subjects without a clinical diagnosis of FH (Dutch score ≤ 3). All subjects were on statin treatment at the time of the enrollment. RESULTS No difference of glucose and lipid profile was found in the two groups. FH patients had higher S100A12 plasma levels than non-FH subjects (12.87 ± 4.82 vs. 8.57 ± 4.87 ng/mL, p < 0.01). No difference of hs-CRP, sRAGE and esRAGE was found between the two groups. Also, PWV was higher in FH patients than non-FH subjects (8.63 ± 0.92 vs. 6.68 ± 0.73 m/s, p < 0.05). Finally, S100A12 was independently correlated with age (p < 0.01), genetic mutation (p < 0.01) and PWV (p < 0.001). CONCLUSIONS FH patients exhibited higher S100A12 levels than non-FH subjects. A novel vascular inflammation pathway, other than hs-CRP, might be useful to better characterize cardiovascular risk profile.
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The cholesterol biosynthesis pathway regulates IL-10 expression in human Th1 cells.
Perucha, E, Melchiotti, R, Bibby, JA, Wu, W, Frederiksen, KS, Roberts, CA, Hall, Z, LeFriec, G, Robertson, KA, Lavender, P, et al
Nature communications. 2019;(1):498
Abstract
The mechanisms controlling CD4+ T cell switching from an effector to an anti-inflammatory (IL-10+) phenotype play an important role in the persistence of chronic inflammatory diseases. Here, we identify the cholesterol biosynthesis pathway as a key regulator of this process. Pathway analysis of cultured cytokine-producing human T cells reveals a significant association between IL-10 and cholesterol metabolism gene expression. Inhibition of the cholesterol biosynthesis pathway with atorvastatin or 25-hydroxycholesterol during switching from IFNγ+ to IL-10+ shows a specific block in immune resolution, defined as a significant decrease in IL-10 expression. Mechanistically, the master transcriptional regulator of IL10 in T cells, c-Maf, is significantly decreased by physiological levels of 25-hydroxycholesterol. Strikingly, progression to rheumatoid arthritis is associated with altered expression of cholesterol biosynthesis genes in synovial biopsies of predisposed individuals. Our data reveal a link between sterol metabolism and the regulation of the anti-inflammatory response in human CD4+ T cells.
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Cdc42 - A tryst between host cholesterol metabolism and infection.
Sviridov, D, Mukhamedova, N
Small GTPases. 2018;(3):237-241
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Abstract
Emerging evidence points to an important connection between pathogenesis of intracellular infections and host cholesterol metabolism. In our study we demonstrated that human cytomegalovirus exploits host small GTPase Cdc42 to hijack cellular cholesterol efflux pathway. It appears that the virus uses host machinery to stimulate cholesterol efflux by modifying lipid rafts and altering properties of plasma membrane, but the altered pathway is controlled by the viral protein US28 instead of the host ATP binding cassette transporter A1. We speculate that virus-controlled remodeling of plasma membrane facilitates immune evasion, exocytosis of viral proteins and cell-to-cell transmission of human cytomegalovirus. These mechanisms may be not unique for the cytomegalovirus and subverting reverse cholesterol transport pathway may be a generic mechanism used by pathogens to alter properties of host plasma membrane adapting it for their purposes-to hide and disseminate.
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A randomized clinical trial in vitamin D-deficient adults comparing replenishment with oral vitamin D3 with narrow-band UV type B light: effects on cholesterol and the transcriptional profiles of skin and blood.
Ponda, MP, Liang, Y, Kim, J, Hutt, R, Dowd, K, Gilleaudeau, P, Sullivan-Whalen, MM, Rodrick, T, Kim, DJ, Barash, I, et al
The American journal of clinical nutrition. 2017;(5):1230-1238
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Abstract
Background: Vitamin D deficiency, defined as a serum 25-hydroxyvitamin D [25(OH)D] concentration <20 ng/mL, is correlated with a more atherogenic lipid profile. However, oral vitamin D supplementation does not lower LDL-cholesterol concentrations or raise HDL-cholesterol concentrations. This uncoupling between association and causation may result from a failure of oral vitamin D to mimic the effect of dermally synthesized vitamin D in response to ultraviolet type B (UVB) light.Objective: We tested the hypothesis that, in vitamin D-deficient adults, the replenishment of vitamin D with UVB exposure would lower LDL-cholesterol concentrations compared with the effect of oral vitamin D3 supplementation.Design: We performed a randomized clinical trial in vitamin D-deficient adults and compared vitamin D replenishment between subjects who received oral vitamin D3 (n = 60) and those who received narrow-band UVB exposure (n = 58) ≤6 mo.Results: There was no difference in the change from baseline LDL-cholesterol concentrations between oral vitamin D3 and UVB groups (difference in median of oral vitamin D3 minus that of UVB: 1.5 mg/dL; 95% CI: -5.0, 7.0 mg/dL). There were also no differences within groups or between groups for changes in total or HDL cholesterol or triglycerides. Transcriptional profiling of skin and blood, however, revealed significant upregulation of immune pathway signaling with oral vitamin D3 but significant downregulation with UVB.Conclusions: Correcting vitamin D deficiency with either oral vitamin D3 or UVB does not improve the lipid profile. Beyond cholesterol, these 2 modalities of raising 25(OH)D have disparate effects on gene transcription. This trial was registered at clinicaltrials.gov as NCT01688102.