Reduced Cholesterol Synthesis Research Articles

Effects of Simvastatin on inflammatory response and biological behavior of adamantinomatous craniopharyngioma.

To investigate the autoinflammatory effect and biological behaviour of simvastatin (SIM) on adamantinomatous craniopharyngioma (ACP) cells. Craniopharyngiomas imaging, intraoperative observations, and tumour histopathology were employed to investigate the correlation between esters and craniopharyngiomas. Filipin III fluorescent probe verified the validity of SIM on the alternations of synthesized cholesterol in craniopharyngioma cells. The cell counting kit-8 (CCK8) assay detected the impacts of SIM on cell proliferation and determined the IC50 value of tumour cells. Reverse transcription polymerase chain reaction (RT-PCR) measured the expression of inflammatory factors. Flow cytometry technique detected the cell cycle and apoptosis, and cell scratch assay judged the cell migration. Meanwhile, Western blot was adopted to determine the expression of proteins related to inflammation, proliferation, and apoptosis signalling pathways. In the ACP tumour parenchyma, many cholesterol crystalline clefts were observed, and the deposition of esters was closely associated with craniopharyngioma inflammation. After simvastatin intervention, a reduction in cholesterol synthesis within ACP was noted. RT-PCR analysis revealed SIM inhibited the transcription of inflammatory factors in ACP cells. Western blot analysis demonstrated SIM inhibited nuclear factor-kappa B (NF-κB) p65 activation expression while promoted the expressions of Cl-caspase-3 and P38 MAPK. CCK8 assay indicated a decrease in ACP cell activity upon SIM treatment. Scratch assay signified that SIM hindered ACP cell migration. Flow cytometry results suggested that the drug promoted ACP cell apoptosis. SIM suppressed the inflammatory response to craniopharyngiomas by inhibiting craniopharyngioma cholesterol synthesis, inhibited proliferation of ACP cells, and promoted their apoptosis.

The Potential of Flavonoid Derivative Compounds as Inhibitors of the HMG-CoA Reductase Enzyme for Candidate of Hypercholesterolemia Drugs

Cardiovascular disease (CVD) is a disease that causes death in the world. Behavioral risk factors are crucial in dealing with CVD disease. High levels of cholesterol in the blood are associated with hypercholesterolemia. It can increase the risk of CVD disease. The HMG-CoA reductase enzyme is an enzyme that plays a role in cholesterol synthesis. It will convert the HMG-CoA compound into the mevalonate. Inhibition of this enzyme can reduce cholesterol synthesis because it inhibits the formation of mevalonate, which is the initial stage of cholesterol synthesis. Herbal compounds are compounds produced by plants. It has good benefits for the body. Flavonoid compounds can be beneficial for health. Molecular docking is a method used to determine the binding affinity and interaction values ​​of the enzyme protein interaction with the ligand to be bound. The results of Apigenin binding affinity values is -7.7 kcal/mol, Luteolin is -8 kcal/mol, Quercetin is -8.2 kcal/mol, Kaempferol is -7.4 kcal/mol, Phloretin is -6.8 kcal/mol, Chalconaringenin is -6.9 kcal/mol, Cyanidin is -7.9 kcal/mol, Delphinidin is -7.8 kcal/mol, Hesperetin is -7.7 kcal/mol, Narigenin is -7.8 kcal/mol, Daidzein is -6.8 kcal/mol, Genistein is -7 kcal/mol, Rutin is -9.2 kcal/mol, Taxifolin is -8 kcal /mol, Diosmetin is -7.6 kcal/mol, and its native ligand Rosuvastatin is -8.5 kcal/mol. Flavonoid derivative compounds can bind to the HMG-CoA reductase enzyme. They can be candidates for antihyperlipidemia drugs.

Estrogen induces LCAT to maintain cholesterol homeostasis and suppress hepatocellular carcinoma development.

Hepatocellular carcinoma (HCC) is an aggressive disease that occurs predominantly in men. Estrogen elicits protective effects against HCC development. Elucidation of the estrogen-regulated biological processes that suppress HCC could lead to improved prevention and treatment strategies. Here, we performed transcriptomic analyses on mouse and human liver cancer and identified LCAT as the most highly estrogen-upregulated gene and a biomarker of favorable prognosis. LCAT upregulation inhibited HCC in vitro and in vivo and mediated estrogen-induced suppression of HCC in an ESR1-dependent manner. LCAT facilitated high-density lipoprotein cholesterol (HDL-C) production and uptake via the LDLR and SCARB1 pathways. Consistently, high HDL-C levels corresponded to a favorable prognosis in HCC patients. The enhanced HDL-C absorption induced by LCAT impaired SREBP2 maturation, which ultimately suppressed cholesterol biosynthesis and dampened HCC cell proliferation. HDL-C alone inhibited HCC growth comparably to the cholesterol-lowering drug lovastatin, and SREBF2 overexpression abolished the inhibitory activity of LCAT. Clinical observations and cross-analyses of multiple databases confirmed the correlation of elevated LCAT and HDL-C levels to reduced cholesterol synthesis and improved HCC patient prognosis. Furthermore, LCAT deficiency mimicked whereas LCAT overexpression abrogated the tumor growth promoting effects of ovariectomy in HCC-bearing female mice. Most importantly, HDL-C and LCAT delayed the development of subcutaneous tumors in nude mice, and HDL-C synergized with lenvatinib to eradicate orthotopic liver tumors. Collectively, this study reveals that estrogen upregulates LCAT to maintain cholesterol homeostasis and dampen hepatocarcinogenesis. LCAT and HDL-C represent potential prognostic and therapeutic biomarkers for targeting cholesterol homeostasis as a strategy for treating HCC.

Hypercapnia increases ACE2 expression and pseudo-SARS-CoV-2 entry in bronchial epithelial cells by augmenting cellular cholesterol.

Patients with chronic lung disease, obesity, and other co-morbid conditions are at increased risk of severe illness and death when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hypercapnia, the elevation of CO2 in blood and tissue, commonly occurs in patients with severe acute and chronic lung disease, including those with pulmonary infections, and is also associated with high mortality risk. We previously reported that hypercapnia increases viral replication and mortality of influenza A virus infection in mice. We have also shown that culture in elevated CO2 upregulates expression of cholesterol synthesis genes in primary human bronchial epithelial cells. Interestingly, factors that increase the cholesterol content of lipid rafts and lipid droplets, platforms for viral entry and assembly, enhance SARS-CoV-2 infection. In the current study, we investigated the effects of hypercapnia on ACE2 expression and entry of SARS-CoV-2 pseudovirus (p-SARS-CoV-2) into airway epithelial cells. We found that hypercapnia increased ACE2 expression and p-SARS-CoV-2 uptake by airway epithelium in mice, and in cultured VERO and human bronchial epithelial cells. Hypercapnia also increased total cellular and lipid raft-associated cholesterol in epithelial cells. Moreover, reducing cholesterol synthesis with inhibitors of sterol regulatory element binding protein 2 (SREBP2) or statins, and depletion of cellular cholesterol, each blocked the hypercapnia-induced increases in ACE2 expression and p-SARS-CoV-2 entry into epithelial cells. Cigarette smoke extract (CSE) also increased ACE2 expression, p-SARS-CoV-2 entry and cholesterol accumulation in epithelial cells, an effect not additive to that of hypercapnia, but also inhibited by statins. These findings reveal a mechanism that may account, in part, for poor clinical outcomes of SARS-CoV-2 infection in patients with advanced lung disease and hypercapnia, and in those who smoke cigarettes. Further, our results suggest the possibility that cholesterol-lowering therapies may be of particular benefit in patients with hypercapnia when exposed to or infected with SARS-CoV-2.

Development and Optimization of Fluvastatin Sodium Loaded Biodegradable Microspheres

Fluvastatin sodium is a hypolipidemic agent that reduces cholesterol synthesis by inhibiting HMG-COA reductase. The drug has a comparatively short biological half-life (1.2 hours) and low bioavailability (24– 29%), making it an appropriate candidate for a sustained-release drug delivery system. This study aimed to formulate biodegradable microspheres of fluvastatin sodium by optimization through an experimental design approach. Microspheres containing fluvastatin sodium were prepared by o/w emulsification solvent evaporation method using poly (lactic-co-glycolic acid) (PLGA 50:50) as a biodegradable polymer. 32 full factorial design was applied to study the effect of drug to polymer ratio and stirring speed on dependent variables, i.e. particle size, entrapment efficiency, Q1h, t80%. Prepared formulations were subjected to evaluate physicochemical properties and release characteristics. DSC and FTIR proved no interaction between the drug and excipients. Microspheres possessed size in the range of 193 to 344 μm and entrapment efficiency varied from 63.1 to 85.6%. Formulations showed drug release up to 23% within 1-hour. while t80% was found in between 3–9 hours. Regression analysis and ANOVA results suggested a significant effect (p<0.05) of variables on responses. The results of the present study suggested that biodegradable microspheres of fluvastatin sodium prepared using poly (lactic-co-glycolic acid) can be a promising alternative for conventional delivery and suitable for sustained drug release.

Improving statins production: From non-genetic strategies to genetic strategies.

Statins are lipid-lowering drugs that selectively inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, effectively reducing cholesterol synthesis. With improved nutritional conditions, the demand for statins is increasing in the global market. The use of microbial cell factories for statin biosynthesis has become advantageous due to the rapid advancements in biotechnology. These approaches offer simple operation and easy separation of products. This review provides an overview the strategies for statins production via microbial cell factories, including both traditional fermentation culture (non-genetic) and modern synthetic biology manufacture (genetic). Firstly, the complex fermentation parameters and process control technology on submerged fermentation (SmF) and solid-state fermentation (SSF) are introduced in detail. The potential use of recoverable agricultural wastes/(biomass) as a fermentation substrate in SSF for statin production is emphasized. Additionally, metabolic engineering strategies for constructing robust engineering strains and directed evolution are also discussed. The review highlights the potential and challenges of using microbial cell factories for statin production, and aims to promote greener production modes for statins.

Aerobic Exercise Facilitates the Nuclear Translocation of SREBP2 by Activating AKT/SEC24D to Contribute Cholesterol Homeostasis for Improving Cognition in APP/PS1 Mice.

Impaired cholesterol synthesizing ability is considered a risk factor for the development of Alzheimer's disease (AD), as evidenced by reduced levels of key proteases in the brain that mediate cholesterol synthesis; however, cholesterol deposition has been found in neurons in tangles in the brains of AD patients. Although it has been shown that statins, which inhibit cholesterol synthesis, reduce the incidence of AD, this seems paradoxical for AD patients whose cholesterol synthesizing capacity is already impaired. In this study, we aimed to investigate the effects of aerobic exercise on cholesterol metabolism in the brains of APP/PS1 mice and to reveal the mechanisms by which aerobic exercise improves cognitive function in APP/PS1 mice. Our study demonstrates that the reduction of SEC24D protein, a component of coat protein complex II (COPII), is a key factor in the reduction of cholesterol synthesis in the brain of APP/PS1 mice. 12 weeks of aerobic exercise was able to promote the recovery of SEC24D protein levels in the brain through activation of protein kinase B (AKT), which in turn promoted the expression of mem-brane-bound sterol regulatory element-binding protein 2 (SREBP2) nuclear translocation and the expression of key proteases mediating cholesterol synthesis. Simultaneous aerobic exercise restored cholesterol transport capacity in the brain of APP/PS1 mice with the ability to efflux excess cholesterol from neurons and reduced neuronal lipid rafts, thereby reducing cleavage of the APP amyloid pathway. Our study emphasizes the potential of restoring intracerebral cholesterol homeostasis as a therapeutic strategy to alleviate cognitive impairment in AD patients.

Ligustilide covalently binds to Cys129 of HMGCS1 to ameliorate dyslipidemia

Dyslipidemia is characterized by elevated levels of total cholesterol and triglycerides in serum, and has become the primary human health killer because of the major risk factors for cardiovascular diseases. Although there exist plenty of drugs for dyslipidemia, the number of patients who could benefit from lipid-lowering drugs still remains a concern. Ligustilide (Lig), a natural phthalide derivative, was reported to regulate lipid metabolic disorders. However, its specific targets and underlying molecular mechanism are still unclear. In this study, we found that Lig alleviated high fat diet-induced dyslipidemia by inhibiting cholesterol biosynthesis. Furthermore, a series of chemical biological analysis methods were used to identify its target protein for regulating lipid metabolism. Collectively, 3-hydroxy-3-methylglutaryl coenzyme A synthetase 1 (HMGCS1) of hepatic cells was identified as a target for Lig to regulate lipid metabolism. The mechanistic study confirmed that Lig irreversibly binds to Cys129 of HMGCS1 via its metabolic intermediate 6,7-epoxyligustilide, thereby reducing cholesterol synthesis and improving lipid metabolism disorders. These findings not only systematically elucidated the lipid-lowering mechanism of Lig, but also provided a new structural compound for the treatment of dyslipidemia.

Effect of the JAK/STAT Inhibitor Tofacitinib on Macrophage Cholesterol Metabolism.

The impact of JAK/STAT inhibitors, which are used in various inflammatory diseases, on cardiovascular risk is controversial and has recently raised safety concerns. Our study investigates the direct effects of tofacitinib on macrophage cholesterol metabolism, which is crucial for atherosclerosis plaque development and stability. Cultured human macrophages THP-1 were used to assess the impact of tofacitinib on cell cholesterol efflux and synthesis via radioisotopic methods, and on cholesterol uptake by measuring the cell cholesterol content with a fluorometric assay. The cholesterol acceptors and donors were either standard lipoproteins or sera from patients with juvenile idiopathic arthritis (JIA) and from control subjects. Tofacitinib significantly increased the macrophage cholesterol efflux to all acceptors; it reduced cholesterol uptake from both the normal and hypercholesterolemic sera; and it reduced cholesterol synthesis. The treatment of macrophages with tofacitinib was able to increase the cholesterol efflux and decrease cholesterol uptake when using sera from untreated JIA patients with active disease as cholesterol acceptors and donors, respectively. In conclusion, our in vitro data support the concept that tofacitinib has a favorable impact on macrophage cholesterol metabolism, even in the presence of sera from rheumatologic patients, and suggest that other mechanisms may be responsible for the cardiovascular risk associated with tofacitinib use in selected patient populations.

Regulation of cholesterol metabolism during high fatty acid–induced lipid deposition in calf hepatocytes

Cholesterol in the circulation is partly driven by changes in feed intake, but aspects of cholesterol metabolism during development of fatty liver are not well known. The objective of this study was to investigate mechanisms of cholesterol metabolism in calf hepatocytes challenged with high concentrations of fatty acids (FA). To address mechanistic insights regarding cholesterol metabolism, liver samples were collected from healthy control dairy cows (n = 6; 7-13 d in milk) and cows with fatty liver (n = 6; 7-11 d in milk). In vitro, hepatocytes isolated from 3 healthy female calves (1 d old) were challenged with or without a mix of 1.2 mM FA to induce metabolic stress. In addition, hepatocytes were processed with 10 µmol/L of the cholesterol synthesis inhibitor simvastatin or 6 µmol/L of the cholesterol intracellular transport inhibitor U18666A with or without the 1.2 mM FA mix. To evaluate the role of cholesterol addition, hepatocytes were treated with 0.147 mg/mL methyl-β-cyclodextrin (MβCD + FA) or 0.147 mg/mL MβCD with or without 10 and 100 µmol/L cholesterol before incubation with FA (CHO10 + FA and CHO100 + FA). In vivo data from liver biopsies were analyzed by 2-tailed unpaired Student's t-test. Data from in vitro calf hepatocytes were analyzed by one-way ANOVA. Compared with healthy cows, blood plasma total cholesterol and plasma low-density lipoprotein cholesterol content in cows with fatty liver was markedly lower, whereas the hepatic total cholesterol content did not differ. In contrast, compared with healthy controls, the triacylglycerol content in the liver and the content of FA, β-hydroxybutyrate, and aspartate aminotransferase in the plasma of cows with fatty liver were greater. The results revealed that both fatty liver in vivo and challenge of calf hepatocytes with 1.2 mM FA in vitro led to greater mRNA and protein abundance of sterol regulatory element binding transcription factor 1 (SREBF1) and fatty acid synthase (FASN). In contrast, mRNA and protein abundance of sterol regulatory element binding transcription factor 2 (SREBF2), acyl coenzyme A-cholesterol acyltransferase, and ATP-binding cassette subfamily A member 1 (ABCA1) were lower. Compared with the FA group, the cholesterol synthesis inhibitor simvastatin led to greater protein abundance of microsomal triglyceride transfer protein and mRNA abundance of SREBF2, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), ACAT2, and lower ABCA1 and FASN protein abundance. In contrast, compared with the FA group, the cholesterol intracellular transport inhibitor U18666A + FA led to greater total cholesterol concentration and greater protein and mRNA abundance of FASN. Compared with the MβCD + FA group, the addition of 10 µmol/L cholesterol led to greater concentration of cholesteryl ester and excretion of apolipoprotein B100, and greater protein and mRNA abundance of ABCA1 and microsomal triglyceride transfer protein, and lower concentration of malondialdehyde. Overall, a reduction in cholesterol synthesis promoted FA metabolism in hepatocytes likely to relieve the oxidative stress caused by the high FA load. The data suggest that maintenance of normal cholesterol synthesis promotes very low-density lipoprotein excretion and can reduce lipid accumulation and oxidative stress in dairy cows that experience fatty liver.

Effects of 3-Hydroxy-3-methylglutaryl-CoA Reductase Inhibitors on Cholesterol Metabolism in Laying Hens.

This study aimed to investigate the effect of HMGCR inhibitors on egg yolk cholesterol content and its biological mechanisms. Four groups of 180-day-old laying hens (n = 8 cages/group, 6 laying hens/cage) were fed a corn/soybean-based diet (control) and the control diet supplemented with an HMGCR inhibitor at 60, 150, and 300 mg/kg for 4 weeks. The experimental results showed that adding HMGCR inhibitors of 150 mg/kg or more can significantly reduce the cholesterol content in the liver, yolk, serum, and pectoral muscles of laying hens. The RNA-seq results showed that compared with the control group, the addition of HMGCR inhibitors of 150 mg/kg or more to the diet significantly upregulated genes related to cholesterol synthesis in the liver, and the genes involved in steroid synthesis and metabolism, sterol synthesis and metabolism, and cholesterol synthesis and metabolism were all affected by the HMGCR inhibitors. In summary, adding HMGCR inhibitors of 150 mg/kg or more to the diet of hens can significantly reduce the cholesterol content in egg yolk. After the HMGCR inhibitors inhibited the activity of the liver HMGCR, they also altered the expression of genes related to cholesterol synthesis, bile acid synthesis, and cholesterol transport in the liver, and ultimately reduced cholesterol synthesis and cholesterol transport to the egg yolk.

Bempedoic acid: mechanism of action and therapeutic use in atherosclerotic cardiovascular diseases and diabetes

Bempedoic acid is a new cholesterol-lowering drug that recently received approval from the US Food and Drug Administration and the European Medicines Agency. This drug targets lipid and glucose metabolism as well as inflammation by downregulating the ATP citrate lyase and upregulating of AMP-activated protein kinase (AMPK). The main effect is to reduce cholesterol synthesis in the liver, and its use is generally not associated with undesirable muscle disorders. Bempedoic acid can reduce the processes of gluconeogenesis, which leads to an improvement in insulin sensitivity, glucose metabolism and features of the metabolic syndrome. The anti-inflammatory effect of bempedoic acid is mainly achieved by activating the AMPK pathway in immune cells, which helps reduce the level of C-reactive protein in plasma. The effects of bempedoic acid on the course of atherosclerotic cardiovascular disease, type2 diabetes and chronic liver disease have been evaluated in randomized clinical trials that require further research. Phase III clinical safety trial show that bempedoic acid is generally well tolerated in combination with statins, ezetimibe, or proprotein convertase subtilisin/kexin type 9 inhibitors in achieving target levels of low-density lipoprotein cholesterol. The aim of this review is to analyze the main mechanisms of action, potential clinical targets of bempedoic acid and describe the existing evidence from clinical trials. The search was done in the Scopus, Science Direct (from Elsevier), and PubMed databases, including the Medline. The following keywords were used: bempedoic acid, low-density lipoprotein cholesterol, atherosclerotic cardiovascular diseases, diabetes. In order to identify research results that could not be found during the online search, a manual search of the bibliography of publications was used.

Transcriptomic analysis of adipose, hepatic, and mammary gland tissues in lactating cows with elevated peripheral serotonin

Lactation is a highly energy intensive state, particularly for dairy cattle, which have been genetically selected for copious milk secretion. Blood serotonin content is greatly increased during lactation, at least in part because of increased production by the lactating mammary glands. We hypothesized that increasing peripheral serotonin in lactating cows, by infusion of the serotonin precursor 5-hydroxytryptophan (5-HTP), would alter gene expression in metabolically active tissues to support energy partitioning towards lactation.To test this hypothesis, multiparous midlactation Holstein cows (n=8/treatment) were intravenously infused with 5-HTP (1mg/kg bodyweight) or saline over two 10-day treatment periods. Treatments were infused via jugular catheters for 1h/day starting at 0700, on days 1–3 and 8–10, with no infusions on days 4–7. On day 10, 6h after the last infusion, biopsies of subcutaneous white adipose (WAT), hepatic, and mammary tissues were performed. Total RNAs were extracted from these tissues, and followed by whole transcriptome sequencing. Adapter-trimmed sequences were mapped to the cattle reference genome (ARS-UCD 1.2) using STAR. Differential gene expression analysis was done using DEseq2. A combinatory cutoff of mean read count≥5, fold-change≥2, and p-value<0.01 was used to determine differentially expressed genes (DEG). Relative to saline-infused cows, 5-HTP cows had 152 genes downregulated and 38 upregulated in WAT, 117 genes downregulated and 141 upregulated in hepatic tissue, and 79 genes downregulated and 86 upregulated in mammary tissue.DEG from each tissue were then analyzed by QIAGEN Ingenuity Pathway Analysis (IPA) to identify enriched pathways and functions impacted by 5-HTP. In WAT, downregulated genes were enriched in triacylglycerol biosynthesis and upregulated genes were enriched in PPAR signaling, with upregulated gene enrichment in several apoptosis-related pathways as well. Decreased biological function categories in WAT included carbohydrate metabolism and lipid metabolism. In hepatic tissue, downregulated genes were enriched in superpathway of cholesterol biosynthesis while upregulated genes were enriched in cAMP-mediated signaling and citrulline biosynthesis. In mammary tissue, 5-HTP infusion exclusively upregulated genes involved in lipid metabolism, including functions in transport, export, flux and efflux of lipids and cholesterol. In conclusion, lactating cows with elevated peripheral serotonin developed a systemic response, altering the expression of genes in energy metabolic pathways, including reduced lipid synthesis and cell survival in WAT, reduced cholesterol synthesis in the liver, and increased lipid trafficking in the mammary tissue. Together, these changes may function to shift energy partitioning towards milk synthesis. This work was supported by USDA-NIFA Predoctoral Fellowship grant #2021-67034-35172 and research funding provided by Adisseo Bluestar Co. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect Consumption of Papaya and Jicama Juice to Total Cholesterol Levels in Hypercholesterolemia Patients

Hypercholesterolemia is a metabolic disorder of lipoproteins which is characterized by high total cholesterol levels. Papaya and Jicama juice contains vitamin C. This is benefit to regulate the concentration of lipid plasma by inhibits the micelles forming, binding of bile through feces and produces short chain fatty acid that can reduce cholesterol synthesis. This study aimed to determined the effect of Papaya and Jicama Juice to decreased total cholesterol level of hypercholesterolemia patient at dr. M.Suherman Clinic Jember. This study was Quasy Experimental pretest-posttest with control group design. Total subjects were 24 taken by purposive sampling and divided into 2 group, namely control group (24) and treatment group (24) who consumed 180 ml of papaya and jicama juice, containing 65,45mg vitamin C for 7 days, once a day. The criteria of subjects was aged 30-60 years who had total cholesterol levels 200-240 mg/dl. Measurement of total cholesterol used GCU-meter Easy Touch. Data were analyzed used Independent t-test and paired t-tes. The results was total cholesterol level in treatment group before consumed juice was 226.17 mg/dl decreased 176.25 mg/dl after the juice was given. However, papaya and jicama juice had no significant effect (p=0.0103) on the decrease of total cholesterol levels.

Regulation of astrocyte lipid metabolism and ApoE secretion by the microglial oxysterol, 25-hydroxycholesterol

Neuroinflammation, a major hallmark of Alzheimer’s disease and several other neurological and psychiatric disorders, is often associated with dysregulated cholesterol metabolism. Relative to homeostatic microglia, activated microglia express higher levels of Ch25h, an enzyme that hydroxylates cholesterol to produce 25-hydroxycholesterol (25HC). 25HC is an oxysterol with interesting immune roles stemming from its ability to regulate cholesterol metabolism. Since astrocytes synthesize cholesterol in the brain and transport it to other cells via ApoE-containing lipoproteins, we hypothesized that secreted 25HC from microglia may influence lipid metabolism as well as extracellular ApoE derived from astrocytes. Here, we show that astrocytes take up externally added 25HC and respond with altered lipid metabolism. Extracellular levels of ApoE lipoprotein particles increased after treatment of astrocytes with 25HC without an increase in Apoe mRNA expression. In mouse astrocytes-expressing human ApoE3 or ApoE4, 25HC promoted extracellular ApoE3 better than ApoE4. Increased extracellular ApoE was due to elevated efflux from increased Abca1 expression via LXRs as well as decreased lipoprotein reuptake from suppressed Ldlr expression via inhibition of SREBP. 25HC also suppressed expression of Srebf2, but not Srebf1, leading to reduced cholesterol synthesis in astrocytes without affecting fatty acid levels. We further show that 25HC promoted the activity of sterol-o-acyl transferase that led to a doubling of the amount of cholesteryl esters and their concomitant storage in lipid droplets. Our results demonstrate an important role for 25HC in regulating astrocyte lipid metabolism.

Lipopolysaccharide and statin-mediated immune-responsive protein networks revealed in macrophages through affinity purification spacer-arm controlled cross-linking (AP-SPACC) proteomics.

Toll-like receptor 4 (TLR4), a pattern recognition receptor, is activated by lipopolysaccharides (LPS) and induces the MyD88 pathway, which subsequently produces pro-inflammatory cytokines through activation of transcriptional nuclear factor (NF)-κB. Statins have been widely prescribed to reduce cholesterol synthesis for patients with cardiovascular disease. Statins may have pleiotropic effects, which include anti- and pro-inflammatory effects on cells. The molecular mechanism of the sequential influence of LPS and statin on the innate immune system remains unknown. We employed affinity purification-spacer-arm controlled cross-linking (AP-SPACC) MS-based proteomics analysis to identify the LPS- and statin-LPS-responsive proteins and their networks. LPS-stimulated RAW 264.7 macrophage cells singly and combined with the drug statin used in this study. Two chemical cross-linkers with different spacer chain lengths were utilized to stabilize the weak and transient interactors. Proteomic analysis identified 1631 differentially expressed proteins. We identified 151 immune-response proteins through functional enrichment analysis and visualized their interaction networks. Selected candidate protein-coding genes were validated, specifically squamous cell carcinoma antigens recognized by T cells 3, sphingosine-1-phosphate lyase 1, Ras-related protein Rab-35, and tumor protein D52 protein-coding genes through transcript-level expression analysis. The expressions of those genes were significantly increased upon statin treatment and decreased in LPS-stimulated macrophage cells. Therefore, we presumed that the expression changes of genes occurred due to immune response during activation of inflammation. These results highlight the immune-responsive proteins network, providing a new platform for novel investigations and discovering future therapeutic targets for inflammatory diseases.

Mechanism of action and therapeutic use of bempedoic acid in atherosclerosis and metabolic syndrome.

Bempedoic acid is a new cholesterol-lowering drug, which has recently received US FDA and EMA approval. This drug targets lipid and glucose metabolism as well as inflammation via downregulation of ATP-citrate lyase and upregulation of AMP-activated protein kinase (AMPK). The primary effect is the reduction of cholesterol synthesis in the liver and its administration is generally not associated to unwanted muscle effects. Suppression of hepatic fatty acid synthesis leads to decreased triglycerides and, possibly, improved non-alcoholic fatty liver disease. Bempedoic acid may decrease gluconeogenesis leading to improved insulin sensitivity, glucose metabolism, and metabolic syndrome. The anti-inflammatory action of bempedoic acid is mainly achieved via activation of AMPK pathway in the immune cells, leading to decreased plasma levels of C-reactive protein. Effects of bempedoic acid on atherosclerotic cardiovascular disease, type 2 diabetes and chronic liver disease have been assessed in randomized clinical trials but require further confirmation. Safety clinical trials in phase III indicate that bempedoic acid administration is generally well-tolerated in combination with statins, ezetimibe, or proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors to achieve low-density lipoprotein cholesterol targets. The aim of this narrative review on bempedoic acid is to explore the underlying mechanisms of action and potential clinical targets, present existing evidence from clinical trials, and describe practical management of patients.

Changes in regulators of lipid metabolism in the brain: a study of animal models of depression and hypothyroidism

Metabolic disturbances in the brain are assumed to be early changes involved in the pathogenesis of depression, and these alterations may be intensified by a deficiency of thyroid hormones. In contrast to glucose metabolism, the link between altered brain lipids and the pathogenesis of depression is poorly understood, therefore in the present study, we determine transcription factors and enzymes regulating cholesterol and fatty acid biosynthesis in the brain structures in an animal model of depression, hypothyroidism and the coexistence of these diseases.In used model of depression, a decrease in the active form of the transcription factor SREBP-2 in the hippocampus was demonstrated, thus suggesting a reduction in cholesterol biosynthesis. In turn, in the hypothyroidism model, the reduction of cholesterol biosynthesis in the frontal cortex was demonstrated by both the reduction of mature SREBP-2 and the concentration of enzymes involved in cholesterol biosynthesis. The lower expression of LDL receptors in the frontal cortex indicates the restriction of cholesterol uptake into the cells in the model of coexistence of depression and hypothyroidism. Moreover, the identified changes in the levels of SNAP-25, GLP-1R and GLP-2R pointed to disturbances in synaptic plasticity and neuroprotection mechanisms in the examined brain structures.In conclusion, a reduction in cholesterol synthesis in the hippocampus in the model of depression may be the reason for the reduction of synaptic plasticity, whereas a lower level of LDL-R occurring in the frontal cortex in rats from the model of depression and hypothyroidism coexistence could be the reason of anxiogenic and depression-like behaviors.

Simvastatin Inhibits Brucella abortus Invasion into RAW 264.7 Cells through Suppression of the Mevalonate Pathway and Promotes Host Immunity during Infection in a Mouse Model.

Simvastatin is an inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase and has been found to have protective effects against several bacterial infections. In this study, we investigate the effects of simvastatin treatment on RAW 264.7 macrophage cells and ICR mice against Brucella (B.) abortus infections. The invasion assay revealed that simvastatin inhibited the Brucella invasion into macrophage cells by blocking the mevalonic pathway. The treatment of simvastatin enhanced the trafficking of Toll-like receptor 4 in membrane lipid raft microdomains, accompanied by the increased phosphorylation of its downstream signaling pathways, including JAK2 and MAPKs, upon =Brucella infection. Notably, the suppressive effect of simvastatin treatment on Brucella invasion was not dependent on the reduction of cholesterol synthesis but probably on the decline of farnesyl pyrophosphate and geranylgeranyl pyrophosphate synthesis. In addition to a direct brucellacidal ability, simvastatin administration showed increased cytokine TNF-α and differentiation of CD8+ T cells, accompanied by reduced bacterial survival in spleens of ICR mice. These data suggested the involvement of the mevalonate pathway in the phagocytosis of B. abortus into RAW 264.7 macrophage cells and the regulation of simvastatin on the host immune system against Brucella infections. Therefore, simvastatin is a potential candidate for studying alternative therapy against animal brucellosis.

Chitin oligosaccharides alleviate atherosclerosis progress in ApoE-/- mice by regulating lipid metabolism and inhibiting inflammation

Atherosclerosis is driven both by hyperlipidemia and inflammation. Chitin oligosaccharides (NACOS) have shown pharmacological effects on multiple diseases via hypolipidemic and/or anti-inflammatory activities. The present study aims to evaluate whether NACOS treatment can prevent atherosclerosis induced by a high-fat-diet (HFD) in Apolipoprotein E-knockout (ApoE-/-) mice. Results showed that 300 and 900mg/kg b.w./day NACOS supplementation for 14 weeks significantly decreased atherosclerotic lesions up to 45% and 67% in compared with the HFD (P < 0.05), as measured in the valve area of the aortic root. Further, NACOS supplementation significantly reduced the serum hyperlipidemia and circulating proinflammatory cytokines including interleukin-1β, interleukin-6, monocyte chemoattractant protein-1 and tumor necrosis factor-α. NACOS decreased the hepatic Hmgcr to reduce cholesterol synthesis, activated the genes involved in reverse cholesterol transport to enhance cholesterol efflux and excretion, and reduced the intestinal Npc1L1 to lower cholesterol absorption. Additionally, NACOS enhanced cecum short chain fatty acids production and intestinal integrity. Thus, NACOS supplementation ameliorated atherosclerosis via altering lipid metabolism and reducing inflammation. These findings indicate that NACOS may be a potential functional food material for attenuating atherosclerosis development.