Nogo-B inhibition facilitates cholesterol metabolism to reduce hypercholesterolemia.

The strategy of lowering cholesterol levels by promoting cholesterol excretion is still lacking, and few molecular targets act on multiple cholesterol metabolic processes. In this study, we find that Nogo-B deficiency/inhibition simultaneously promotes hepatic uptake of cholesterol and cholesterol excretion. Nogo-B deficiency decreases cholesterol levels by activating ATP-binding cassette transporters (ABCs), apolipoprotein E (ApoE), and low-density lipoprotein receptor (LDLR) expression. We discover that Nogo-B interacts with liver X receptor α (LXRα), and Nogo-B deficiency inhibits ubiquitination degradation of LXRα, thereby enhancing its function on cholesterol excretion. Decreased cellular cholesterol levels further activate SREBP2 and LDLR expression, thereby promoting hepatic uptake of cholesterol. Nogo-B inhibition decreases atherosclerotic plaques and cholesterol levels in mice, and Nogo-B levels are correlated to cholesterol levels in human plasma. In this study, Nogo-B deficiency/inhibition not only promotes hepatic uptake of blood cholesterol but also facilitates cholesterol excretion. This study reports a strategy to lower cholesterol levels by inhibiting Nogo-B expression to promote hepatic cholesterol uptake and cholesterol excretion.

Monitoring of bone matrix acidification by TRAP and ERK biomarkers in the chronic hypercholesterolemia male rats.

Background: Hypercholesterolemia is frequently linked to an elevated risk of cardiovascular diseases, including heart attacks and strokes. Additionally, it could be connected to a higher susceptibility to osteoporosis. Hypercholesterolemia can stimulate the differentiation and activity of osteoclasts, leading to enhanced bone reabsorption and a subsequent net loss of bone tissue. Aim: The purpose of this study was to examine the influence of a high-cholesterol diet on osteoporosis in male rats with differences in biological and oxidative indicators in the hypercholesterolemia diet in male rats. Methods: The samples in this study were twenty male rats, ranging between 1.5 and 2 months, were separated into two groups. In one group, 10 rats were fed a regular diet, while in another group, 10 rats were fed a high-cholesterol diet (2%) over the course of 8 weeks. Samples of blood were obtained at the last stage of the experiment. To calculate physiological and biological markers including extracellular signal-regulated kinase (ERK), tartrate-resistant acid phosphatase (TRAP), hormones, malondialdehyde (MDA), and glutathione (GSH). Results: The results of this study demonstrated a decrease in GSH levels, an increase in ERKs, no significant change in serum TRAP levels, an increase in MDA levels in the blood, and elevated levels of parathyroid hormone, calcitonin, and vitamin D in the cholesterol group. Conclusion: Increased oxidative stress, altered signaling, and disruptions in calcium/bone metabolism associated with cholesterol-related conditions and monitoring biomarker ERK can provide valuable information about disease progression.

Investigating the Role of Cannabinoid Type 1 Receptors in Vascular Function and Remodeling in a Hypercholesterolemic Mouse Model with Low-Density Lipoprotein-Cannabinoid Type 1 Receptor Double Knockout Animals.

Hypercholesterolemia forms the background of several cardiovascular pathologies. LDL receptor-knockout (LDLR-KO) mice kept on a high-fat diet (HFD) develop high cholesterol levels and atherosclerosis (AS). Cannabinoid type 1 receptors (CB1Rs) induce vasodilation, although their role in cardiovascular pathologies is still controversial. We aimed to reveal the effects of CB1Rs on vascular function and remodeling in hypercholesterolemic AS-prone LDLR-KO mice. Experiments were performed on a newly established LDLR and CB1R double-knockout (KO) mouse model, in which KO and wild-type (WT) mice were kept on an HFD or a control diet (CD) for 5 months. The vascular functions of abdominal aorta rings were tested with wire myography. The vasorelaxation effects of acetylcholine (Ach, 1 nM-1 µM) were obtained after phenylephrine precontraction, which was repeated with inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX), Nω-nitro-L-arginine (LNA), and indomethacin (INDO), respectively. Blood pressure was measured with the tail-cuff method. Immunostaining of endothelial NOS (eNOS) was carried out. An HFD significantly elevated the cholesterol levels in the LDLR-KO mice more than in the corresponding WT mice (mean values: 1039 ± 162 mg/dL vs. 91 ± 18 mg/dL), and they were not influenced by the presence of the CB1R gene. However, with the defect of the CB1R gene, damage to the Ach relaxation ability was moderated. The blood pressure was higher in the LDLR-KO mice compared to their WT counterparts (systolic/diastolic values: 110/84 ± 5.8/6.8 vs. 102/80 ± 3.3/2.5 mmHg), which was significantly elevated with an HFD (118/96 ± 1.9/2 vs. 100/77 ± 3.4/3.1 mmHg, p < 0.05) but attenuated in the CB1R-KO HFD mice. The expression of eNOS was depressed in the HFD WT mice compared to those on the CD, but it was augmented if CB1R was knocked out. This newly established double-knockout mouse model provides a tool for studying the involvement of CB1Rs in the development of hypercholesterolemia and atherosclerosis. Our results indicate that knocking out the CB1R gene significantly attenuates vascular damage in hypercholesterolemic mice.

Time-Restricted Feeding Reduces Atherosclerosis in LDLR KO Mice but Not in ApoE Knockout Mice.

BACKGROUND: Dyslipidemia increases cardiovascular disease risk, the leading cause of death worldwide. Under time-restricted feeding (TRF), wherein food intake is restricted to a consistent window of <12 hours, weight gain, glucose intolerance, inflammation, dyslipidemia, and hypercholesterolemia are all reduced in mice fed an obesogenic diet. LDLR (low-density lipoprotein receptor) mutations are a major cause of familial hypercholesterolemia and early-onset cardiovascular disease. METHODS: We subjected benchmark preclinical models, mice lacking LDLR-knockout or ApoE knockout to ad libitum feeding of an isocaloric atherogenic diet either ad libitum or 9 hours TRF for up to 13 weeks and assessed disease development, mechanism, and global changes in hepatic gene expression and plasma lipids. In a regression model, a subset of LDLR-knockout mice were ad libitum fed and then subject to TRF. RESULTS: TRF could significantly attenuate weight gain, hypercholesterolemia, and atherosclerosis in mice lacking the LDLR-knockout mice under experimental conditions of both prevention and regression. In LDLR-knockout mice, increased hepatic expression of genes mediating ß-oxidation during fasting is associated with reduced VLDL (very-low-density lipoprotein) secretion and lipid accumulation. Additionally, increased sterol catabolism coupled with fecal loss of cholesterol and bile acids contributes to the atheroprotective effect of TRF. Finally, TRF alone or combined with a cholesterol-free diet can reduce atherosclerosis in LDLR-knockout mice. However, mice lacking ApoE, which is an important protein for hepatic lipoprotein reuptake do not respond to TRF. CONCLUSIONS: In a preclinical animal model, TRF is effective in both the prevention and regression of atherosclerosis in LDLR knockout mice. The results suggest TRF alone or in combination with a low-cholesterol diet can be a lifestyle intervention for reducing cardiovascular disease risk in humans.

Comparison of Metabolic Changes after 6 Months of High-Carbohydrate Diet or High-Fat Diet with Low Dose Streptozotocin Injection in Rats.

We compared 2 models of metabolic syndrome in rats: high-fat diet (58% calories) with single streptozotocin injection at a dose of 25 mg/kg and replacement of water with 20% fructose solution. The model with fructose solution did not cause the main signs of metabolic syndrome over 24 weeks: concentrations of glucose, triglycerides, cholesterol, weight, and BP did not significantly differ from the control group (standard diet). At the same time, single streptozotocin administration was followed by the development of persistent hyperglycemia, hypertriglyceridemia, hypercholesterolemia, and signs of visceral obesity. High-fat diet combined with injection of streptozotocin in a low dose can be considered a more representative model of metabolic syndrome in humans.

Homocysteine contributes to atherogenic transformation of the aorta in rabbits in the absence of hypercholesterolemia.

Atherosclerosis, the leading cause of cardiovascular disease, cannot be sufficiently explained by established risk factors, including cholesterol. Elevated plasma homocysteine (Hcy) is an independent risk factor for atherosclerosis and is closely linked to cardiovascular mortality. However, its role in atherosclerosis has not been fully clarified yet. We have previously shown that rabbits fed a diet deficient in B vitamins and choline (VCDD), which are required for Hcy degradation, exhibit an accumulation of macrophages and lipids in the aorta, aortic stiffening and disorganization of aortic collagen in the absence of hypercholesterolemia, and an aggravation of atherosclerosis in its presence. In the current study, plasma Hcy levels were increased by intravenous injections of Hcy into balloon-injured rabbits fed VCDD (VCDD+Hcy) in the absence of hypercholesterolemia. While this treatment did not lead to thickening of aortic wall, intravenous injections of Hcy into rabbits fed VCDD led to massive accumulation of VLDL-triglycerides as well as significant impairment of vascular reactivity of the aorta compared to VCDD alone. In the aorta intravenous Hcy injections into VCDD-fed rabbits led to fragmentation of aortic elastin, accumulation of elastin-specific electron-dense inclusions, collagen disorganization, lipid degradation, and autophagolysosome formation. Furthermore, rabbits from the VCDD+Hcy group exhibited a massive decrease of total protein methylated arginine in blood cells and decreased creatine in blood cells, serum and liver compared to rabbits from the VCDD group. Altogether, we conclude that Hcy contributes to atherogenic transformation of the aorta not only in the presence but also in the absence of hypercholesterolemia.

Influence of Varied Dietary Cholesterol Levels on Lipid Metabolism in Hamsters.

Syrian hamsters are valuable models for studying lipid metabolism due to their sensitivity to dietary cholesterol, yet the precise impact of varying cholesterol levels has not been comprehensively assessed. This study examined the impact of varying dietary cholesterol levels on lipid metabolism in Syrian hamsters. Diets ranging from 0% to 1% cholesterol were administered to assess lipid profiles and oxidative stress markers. Key findings indicate specific cholesterol thresholds for inducing distinct lipid profiles: below 0.13% for normal lipids, 0.97% for elevated LDL-C, 0.43% for increased VLDL-C, and above 0.85% for heightened hepatic lipid accumulation. A cholesterol supplementation of 0.43% induced hypercholesterolemia without adverse liver effects or abnormal lipoprotein expression. Furthermore, cholesterol supplementation significantly increased liver weight, plasma total cholesterol, LDL-C, and VLDL-C levels while reducing the HDL-C/LDL-C ratio. Fecal cholesterol excretion increased, with stable bile acid levels. High cholesterol diets correlated with elevated plasma ALT activities, reduced hepatic lipid peroxidation, and altered leptin and CETP levels. These findings underscore Syrian hamsters as robust models for hyperlipidemia research, offering insights into experimental methodologies. The identified cholesterol thresholds facilitate precise lipid profile manipulation, enhancing the hamster's utility in lipid metabolism studies and potentially informing clinical approaches to managing lipid disorders.

Pitavastatin attenuates hypercholesterolemia-induced decline in serotonin transporter availability.

INTRODUCTION: Hypercholesterolemia is associated with increased inflammation and impaired serotonin neurotransmission, potentially contributing to depressive symptoms. However, the role of statins, particularly pitavastatin, in modulating serotonin transporter (SERT) function within this context remains underexplored. This study aimed to investigate whether pitavastatin counteracts the neurobiological effects of hypercholesterolemia. METHODS: Low-density lipoprotein receptor knockout (LDLR-/-) mice on a C57BL/6 background were assigned to three groups: a control group fed a standard chow diet, a group fed a high-fat diet (HFD), and a third group fed a high-fat diet supplemented with pitavastatin (HFD + Pita). We evaluated the effects of HFD with or without pitavastatin on lipid profiles, inflammatory markers, and SERT availability using small-animal positron emission tomography (PET) scans with the radioligand 4-[18F]-ADAM over a 20-week period. RESULTS: Pitavastatin treatment in HFD-fed mice significantly reduced both total cholesterol and LDL cholesterol levels in HFD-fed mice compared to those on HFD alone. Elevated inflammatory markers such as IL-1α, MCP-1/CCL2, and TNF-α in HFD mice were notably decreased in the HFD + Pita group. PET scans showed reduced SERT availability in the brains of HFD mice; however, pitavastatin improved this in brain regions associated with mood regulation, suggesting enhanced serotonin neurotransmission. Additionally, the sucrose preference test showed a trend towards increased preference in the HFD + Pita group compared to the HFD group, indicating a potential reduction in depressive-like behavior. CONCLUSION: Our findings demonstrate that pitavastatin not only lowers cholesterol and reduces inflammation but also enhances SERT availability, suggesting a potential role in alleviating depressive symptoms associated with hypercholesterolemia. These results highlight the multifaceted benefits of pitavastatin, extending beyond its lipid-lowering effects to potentially improving mood regulation and neurotransmitter function.

[Vitamin D3 alleviates the gastritis that associated with Helicobacter pylori infection in mice with hypercholesterolemia by enhancing the activity of vitamin D receptors in the liver tissue and blocking the signaling pathway of JAK/STAT3].

Objective To investigate whether vitamin D3 (VD3) can alleviate Helicobacter pylori (Hp) infection by reducing blood lipids and inhibiting the Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway. Methods High-cholesterol mouse model and Hp infected mouse model were established. Each was treated with VD3 via oral administration for 8 weeks. Real-time quantitative PCR was used to detect the expression of vitamin D receptor (VDR), insulin-induced gene 2 (Insig-2), and gastrin mRNA. Western blot analysis was used to examine the expression of JAK, STAT3, and cyclooxygenase-2 (COX2) proteins in gastric tissues. Biochemical analyses were performed to measure serum cholesterol levels, and ELISA was utilized to evaluate serum gastrin, interleukin 6 (IL-6), and IL-8 levels, along with histopathological examination of liver and gastric tissues using HE staining. Results After oral administration of VD3, the levels of VDR and Insig-2 in mouse liver tissue significantly increased in the high cholesterol group and the high cholesterol combined with Hp infection group. And the expression of serum gastrin decreased. The expression of JAK, STAT3 in gastric tissues reduced, as did the expression of COX2. Serum cholesterol levels decreased, with no significant changes in IL-6 levels, but a reduction in IL-8 levels. Compared to the control group, the high cholesterol combined with Hp infection group showed reduced hepatic ballooning degeneration and alleviated gastric tissue inflammation. In addition, inflammation in gastric tissue was also reduced in the cholesterol group and the Hp infection group. Conclusion VD3 alleviates gastritis by enhancing the activity of VDR in liver tissues, blocking the JAK/STAT3 signaling pathway, and inhibiting the expression of inflammatory factors.

Electrocontractile remodeling of isolated cardiomyocytes induced during early-stage hypercholesterolemia.

Hypercholesterolemia is one of the most important risk factors for cardiovascular diseases. However, it is mostly associated with vascular dysfunction and atherosclerotic lesions, while evidence of direct effects of hypercholesterolemia on cardiomyocytes and heart function is still incomplete and controversial. In this study, we assessed the direct effects of hypercholesterolemia on heart function and the electro-contractile properties of isolated cardiomyocytes. After 5 weeks, male Swiss mice fed with AIN-93 diet added with 1.25% cholesterol (CHO), developed an increase in total serum cholesterol levels and cardiomyocytes cholesterol content. These changes led to altered electrocardiographic records, with a shortening of the QT interval. Isolated cardiomyocytes displayed a shortening of the action potential duration with increased rate of depolarization, which was explained by increased IK, reduced ICa.L and altered INa voltage-dependent inactivation. Also, reduced diastolic [Ca2+]i was found with preserved adrenergic response and cellular contraction function. However, contraction of isolated hearts is impaired in isolated CHO hearts, before and after ischemia/reperfusion, although CHO heart was less susceptible to arrhythmic contractions. Overall, our results demonstrate that early hypercholesterolemia-driven increase in cellular cholesterol content is associated with direct modulation of the heart and cardiomyocytes' excitability, Ca2+ handling, and contraction.

Deletion of the Murine Ortholog of the Human 9p21.3 Locus Leads to Insulin Resistance and Obesity in Hypercholesterolemic Mice.

The 9p21.3 genomic locus is a hot spot for disease-associated single-nucleotide polymorphisms (SNPs), and its strongest associations are with coronary artery disease (CAD). The disease-associated SNPs are located within the sequence of a long noncoding RNA ANRIL, which potentially contributes to atherogenesis by regulating vascular cell stress and proliferation, but also affects pancreatic ß-cell proliferation. Altered expression of a neighboring gene, CDKN2B, has been also recognized to correlate with obesity and hepatic steatosis in people carrying the risk SNPs. In the present study, we investigated the impact of 9p21.3 on obesity accompanied by hyperlipidemia in mice carrying a deletion of the murine ortholog for the 9p21.3 (Chr4Δ70/Δ70) risk locus in hyperlipidemic Ldlr-/-ApoB100/100 background. The Chr4Δ70/Δ70 mice showed decreased mRNA expression of insulin receptors in white adipose tissue already at a young age, which developed into insulin resistance and obesity by aging. In addition, the Sirt1-Ppargc1a-Ucp2 pathway was downregulated together with the expression of Cdkn2b, specifically in the white adipose tissue in Chr4Δ70/Δ70 mice. These results suggest that the 9p21.3 locus, ANRIL lncRNA, and their murine orthologues may regulate the key energy metabolism pathways in a white adipose tissue-specific manner in the presence of hypercholesterolemia, thus contributing to the pathogenesis of metabolic syndrome.

Role of CETP, PCSK-9, and CYP7-alpha in cholesterol metabolism: Potential targets for natural products in managing hypercholesterolemia.

Cardiovascular diseases (CVDs) are a leading cause of mortality worldwide, primarily affecting the heart and blood vessels, with atherosclerosis being a major contributing factor to their onset. Epidemiological and clinical studies have linked high levels of low-density lipoprotein (LDL) emanating from distorted cholesterol homeostasis as its major predisposing factor. Cholesterol homeostasis, which involves maintaining the balance in body cholesterol level, is mediated by several proteins or receptors, transcription factors, and even genes, regulating cholesterol influx (through dietary intake or de novo synthesis) and efflux (by their conversion to bile acids). Previous knowledge about CVDs management has evolved around modulating these receptors' activities through synthetic small molecules/antibodies, with limited interest in natural products. The central roles of the cholesteryl ester transfer protein (CETP), proprotein convertase subtilisin/kexin type 9 (PCSK9), and cytochrome P450 family 7 subfamily A member 1 (CYP7A1), among other proteins or receptors, have fostered growing scientific interests in understanding more on their regulatory activities and potential as drug targets. We present up-to-date knowledge on the contributions of CETP, PCSK9, and CYP7A1 toward CVDs, highlighting the clinical successes and failures of small molecules/antibodies to modulate their activities. In recommendation for a new direction to improve cardiovascular health, we have presented recent findings on natural products (including functional food, plant extracts, phytochemicals, bioactive peptides, and therapeutic carbohydrates) that also modulate the activities of CETP, PCSK-9, and CYP7A1, and emphasized the need for more research efforts redirected toward unraveling more on natural products potentials even at clinical trial level for CVD management.

Influence of Chronic Forced Immobilization and Consumption of a High-Fat and High-Carbohydrate Diet Containing Cholesterol on Lipid and Cholesterol Metabolism in Male Wistar Rats.

We studied the effect of separate and combined influence of chronic forced physical activity reduction and high-fat and high-carbohydrate diet containing cholesterol on some indicators of carbohydrate, lipid, and cholesterol metabolism in growing male Wistar rats. Used combination of factors simulating a sedentary lifestyle and unhealthy diet did not have a synergistic effect on the selected biomarkers. On the contrary, the effect was antagonistic: body weight and appetite decreased and insulin resistance increased. The obtained results indicate certain prospects of hypercholesterolemia model using in preclinical studies of specialized food products to optimize the diet of individuals with disorders of carbohydrate and lipid metabolism.

High Iron Consumption Modifies the Hepatic Transcriptome Related to Cholesterol Metabolism.

Iron supplementation is a common method for alleviating symptoms of iron deficiency, but excessive iron intake may lead to systemic copper deficiencies and hypercholesterolemia. In our study, we explored the intricate relationship between dietary iron and copper levels and their impact on cholesterol metabolism. Using a rat model, we conducted dietary interventions with varying iron and copper concentrations and analyzed hepatic transcriptomes. High iron intake coupled with low copper intake induced hypercholesterolemia and altered the expression of genes associated with cholesterol and lipid metabolism, thereby, exacerbating cardiovascular disease risks. Conversely, copper supplementation mitigated these hepatic gene expression alterations, suggesting that dietary copper plays a role in cholesterol regulation. Transcriptomic analysis revealed significant upregulation of genes involved in cholesterol synthesis and antioxidative pathways in response to high iron intake, while genes involved in cholesterol elimination were downregulated. Furthermore, high iron consumption was associated with cellular apoptosis and the activation of cholesterol synthesis. Our findings underscore the importance of balanced iron and copper intake in cholesterol homeostasis and highlight the potential of copper supplementation for mitigating iron-induced hypercholesterolemia.

AMPK-mediated regulation of endogenous cholesterol synthesis does not affect atherosclerosis in a murine Pcsk9-AAV model.

BACKGROUND AND AIMS: Dysregulated cholesterol metabolism is a hallmark of atherosclerotic cardiovascular diseases, yet our understanding of how endogenous cholesterol synthesis affects atherosclerosis is not clear. The energy sensor AMP-activated protein kinase (AMPK) phosphorylates and inhibits the rate-limiting enzyme in the mevalonate pathway HMG-CoA reductase (HMGCR). Recent work demonstrated that when AMPK-HMGCR signaling was compromised in an Apoe-/- model of hypercholesterolemia, atherosclerosis was exacerbated due to elevated hematopoietic stem and progenitor cell mobilization and myelopoiesis. We sought to validate the significance of the AMPK-HMGCR signaling axis in atherosclerosis using a non-germline hypercholesterolemia model with functional ApoE. METHODS: Male and female HMGCR S871A knock-in (KI) mice and wild-type (WT) littermate controls were made atherosclerotic by intravenous injection of a gain-of-function Pcsk9D374Y-adeno-associated virus followed by high-fat and high-cholesterol atherogenic western diet feeding for 16 weeks. RESULTS: AMPK activation suppressed endogenous cholesterol synthesis in primary bone marrow-derived macrophages from WT but not HMGCR KI mice, without changing other parameters of cholesterol regulation. Atherosclerotic plaque area was unchanged between WT and HMGCR KI mice, independent of sex. Correspondingly, there were no phenotypic differences observed in hematopoietic progenitors or differentiated immune cells in the bone marrow, blood, or spleen, and no significant changes in systemic markers of inflammation. When lethally irradiated female mice were transplanted with KI bone marrow, there was similar plaque content relative to WT. CONCLUSIONS: Given previous work, our study demonstrates the importance of preclinical atherosclerosis model comparison and brings into question the importance of AMPK-mediated control of cholesterol synthesis in atherosclerosis.

MicroRNA-206 as a potential cholesterol-lowering drug is superior to statins in mice.

Hypercholesterolemia is frequently intertwined with hepatosteatosis, hypertriglyceridemia, and hyperglycemia. This study is designed to assess the therapeutic efficacy of miR-206 in contrast to statins in the context of managing hypercholesterolemia in mice. We previously showed that miR-206 is a potent inhibitor of de novo lipogenesis (DNL), cholesterol synthesis, and gluconeogenesis in mice. Given that these processes occur within hepatocytes, we employed a mini-circle (MC) system to deliver miR-206 specifically to hepatocytes (designated as MC-miR-206). A single intravenous injection of MC-miR-206 maintained high levels of miR-206 in the liver for at least two weeks, thereby maintaining suppression of hepatic DNL, cholesterol synthesis, and gluconeogenesis. MC-miR-206 significantly reduced DNA damage, endoplasmic reticulum and oxidative stress, and hepatic toxicity. Therapeutically, both MC-miR-206 and statins significantly reduced total serum cholesterol and triglycerides as well as LDL cholesterol and VLDL cholesterol in mice maintained on the normal chow and high-fat high-cholesterol diet. MC-miR-206 reduced liver weight, hepatic triglycerides and cholesterol, and blood glucose, while statins slightly increased hepatic cholesterol and blood glucose and failed to affect levels of liver weight and hepatic triglycerides. Mechanistically, miR-206 alleviated hypercholesterolemia by inhibiting hepatic cholesterol synthesis, while statins increased HMGCR activity, hepatic cholesterol synthesis, and fecal-neutral steroid excretion. MiR-206 facilitates the regression of hypercholesterolemia, hypertriglyceridemia, hyperglycemia, and hepatosteatosis. MiR-206 outperforms statins by reducing hyperglycemia, hepatic cholesterol levels, and hepatic toxicity.

Tachol1 QTL on mouse chromosome 1 is responsible for hypercholesterolemia and diet-induced obesity.

Hypercholesterolemia raises the risk for cardiovascular complications and overall health. Hypercholesterolemia is common, affecting 10% of the general population of the US, and heritable. Most individuals with hypercholesterolemia have a polygenic predisposition to the condition. Previously we identified a quantitative trait locus, Tachol1, linked to hypercholesterolemia on mouse chromosome 1 (Chr1) in a cross between C57BL/6J (B6) and TALLYHO/JngJ (TH) mice, a polygenic model for human obesity, type 2 diabetes and hyperlipidemia. Subsequently, using congenic mice that carry a TH-derived genomic segment of Chr1 on a B6 background, we demonstrated that the distal segment of Chr1, where Tachol1 maps, is necessary to cause hypercholesterolemia, as well as diet-induced obesity. In this study, we generated overlapping subcongenic lines to the distal segment of congenic region and characterized subcongenic mice carrying the smallest TH region of Tachol1, ~ 16.2 Mb in size (B6.TH-Chr1-16.2 Mb). Both male and female B6.TH-Chr1-16.2 Mb mice showed a significantly increased plasma total cholesterol levels compared to B6 on both chow and high fat (HF) diet. B6.TH-Chr1-16.2 Mb mice also had greater fat mass than B6 on HF diet, without increasing food intake. The gene and protein expression levels of absent in melanoma 2 (Aim2) gene were significantly upregulated in B6.TH-Chr1-16.2 Mb mice compared to B6. In summary, we confirmed the effect of Tachol1 on hypercholesterolemia and diet-induced obesity using subcongenic analysis.

miR-181d-5p ameliorates hypercholesterolemia by targeting PCSK9.

Hypercholesterolemia is an independent risk factor for cardiovascular disease and lowering circulating levels of low-density lipoprotein cholesterol (LDL-C) can prevent and reduce cardiovascular events. MicroRNA-181d (miR-181d) can reduce the levels of triglycerides and cholesterol esters in cells. However, it is not known whether miR-181d-5p can lower levels of circulating LDL-C. Here, we generated two animal models of hypercholesterolemia to analyze the potential relationship between miR-181d-5p and LDL-C. In hypercholesterolemia model mice, adeno-associated virus (AAV)-mediated liver-directed overexpression of miR-181d-5p decreased the serum levels of cholesterol and LDL-C and the levels of cholesterol and triglyceride in the liver compared with control mice. Target Scan 8.0 indicated Proprotein convertase subtilisin/kexin type 9 (PCSK9) to be a possible target gene of miR-181d-5p, which was confirmed by in vitro experiments. miR-181d-5p could directly interact with both the PCSK9 3'-UTR and promoter to inhibit PCSK9 translation and transcription. Furthermore, Dil-LDL uptake assays in PCSK9 knockdown Huh7 cells demonstrated that miR-181d-5p promotion of LDL-C absorption was dependent on PCSK9. Collectively, our findings show that miR-181d-5p targets the PCSK9 3'-UTR to inhibit PCSK9 expression and to reduce serum LDL-C. miR-181d-5p is therefore a new therapeutic target for the development of anti-hypercholesterolemia drugs.

Effect of hypercholesterolemia on circulating and cardiomyocyte-derived extracellular vesicles.

Hypercholesterolemia (HC) induces, propagates and exacerbates cardiovascular diseases via various mechanisms that are yet not properly understood. Extracellular vesicles (EVs) are involved in the pathomechanism of these diseases. To understand how circulating or cardiac-derived EVs could affect myocardial functions, we analyzed the metabolomic profile of circulating EVs, and we performed an in-depth analysis of cardiomyocyte (CM)-derived EVs in HC. Circulating EVs were isolated with Vezics technology from male Wistar rats fed with high-cholesterol or control chow. AC16 human CMs were treated with Remembrane HC supplement and EVs were isolated from cell culture supernatant. The biophysical properties and the protein composition of CM EVs were analyzed. THP1-ASC-GFP cells were treated with CM EVs, and monocyte activation was measured. HC diet reduced the amount of certain phosphatidylcholines in circulating EVs, independently of their plasma level. HC treatment significantly increased EV secretion of CMs and greatly modified CM EV proteome, enriching several proteins involved in tissue remodeling. Regardless of the treatment, CM EVs did not induce the activation of THP1 monocytes. In conclusion, HC strongly affects the metabolome of circulating EVs and dysregulates CM EVs, which might contribute to HC-induced cardiac derangements.

Dual Deletion of Keap1 and Rbpjκ Genes in Liver Leads to Hepatomegaly and Hypercholesterolemia.

The hepatic deletion of Rbpjκ (RbpjF/F::AlbCre) in the mouse leads to exhibition of the Alagille syndrome phenotype during early postnatal liver development with hyperlipidemia and cholestasis due to attenuated disruption of NOTCH signaling. Given the roles of NRF2 signaling in the regulation of lipid metabolism and bile ductal formation, it was anticipated that these symptoms could be alleviated by enhancing NRF2 signaling in the RbpjF/F::AlbCre mouse by hepatic deletion of Keap1 in compound Keap1F/F::RbpjF/F::AlbCre mice. Unexpectedly, these mice developed higher hepatic and plasma cholesterol levels with more severe cholestatic liver damage during the pre-weaning period than in the RbpjF/F::AlbCre mice. In addition, hypercholesterolemia and hepatic damage were sustained throughout the growth period unlike in the RbpjF/F::AlbCre mouse. These enhanced abnormalities in lipid metabolism appear to be due to NRF2-dependent changes in gene expression related to cholesterol synthetic and subsequent bile acid production pathways. Notably, the hepatic expression of Cyp1A7 and Abcb11 genes involved in bile acid homeostasis was significantly reduced in Keap1F/F::RbpjF/F::AlbCre compared to RbpjF/F::AlbCre mice. The accumulation of liver cholesterol and the weakened capacity for bile excretion during the 3 pre-weaning weeks in the Keap1F/F::RbpjF/F::AlbCre mice may aggravate hepatocellular damage level caused by both excessive cholesterol and residual bile acid toxicity in hepatocytes. These results indicate that a tuned balance of NOTCH and NRF2 signaling is of biological importance for early liver development after birth.