A new feature on the cholesterol-lowering landscape

Tracing ALS Degeneration: Insights from Spinal Cord and Cortex Transcriptomes

BACKGROUND/OBJECTIVES

Amyotrophic Lateral Sclerosis is a progressive neurodegenerative disorder characterized by the loss of upper and lower motor neurons. Key factors contributing to neuronal death include mitochondrial energy damage, oxidative stress, and excitotoxicity. The frontal cortex is crucial for action initiation, planning, and voluntary movements whereas the spinal cord facilitates communication with the brain, walking, and reflexes. By investigating transcriptome data from the frontal cortex and spinal cord, we aim to elucidate common pathological mechanisms and pathways involved in ALS for understanding the disease progression and identifying potential therapeutic targets.

METHODS

In this study, we quantified gene and transcript expression patterns, predicted variants, and assessed their functional effects using computational tools. It also includes predicting variant-associated regulatory effects, constructing functional interaction networks, and performing a gene enrichment analysis.

RESULTS

We found novel genes for the upregulation of immune response, and the downregulation of metabolic-related and defective degradation processes in both the spinal cord and frontal cortex. Additionally, we observed the dysregulation of histone regulation and blood pressure-related genes specifically in the frontal cortex.

CONCLUSIONS

These results highlight the distinct and shared molecular disruptions in ALS, emphasizing the critical roles of immune response and metabolic dysfunction in neuronal degeneration. Targeting these pathways may provide new therapeutic avenues to combat neurodegeneration and preserve neuronal health.

Association of Serum Phosphate with Efficacy of Statin Therapy in Hemodialysis Patients

Background: Statins are less efficacious in reducing cardiovascular disease risk in dialysis patients than in general population. Recent experimental data showed that phosphate excess promotes cellular de novo cholesterol synthesis through 3-hydroxy-3-methylglutaryl coenzyme A reductase activation. Whether this mechanism might account for dialysis patients' resistance to statins has not yet been explored. Patients and Methods: In the present post-hoc analysis we examined the efficacy of statin treatment according to serum phosphate levels in the dialysis patient participants of the AURORA trial (A Study to Evaluate the Use of Rosuvastatin in Subjects on Regular hemodialysis: An Assessment of Survival and Cardiovascular Events), using serum phosphate levels at baseline and during trial course. We first classified the patients by groups of similar phosphate trajectories over time, and tested whether phosphate as a longitudinal exposure (summarized by the identified trajectory groups) modulated the occurrence of major adverse cardiovascular events (MACE) and all-cause death. We replicate the analysis in 4D (Deutsche Diabetes Dialyse Studie) trial. Results: In the AURORA trial, using multivariable analysis we found that the treatment effect of statin on MACE and all-cause death was significant and protective effects in patients with low values of serum phosphate and gradually faded for higher phosphate levels >5 mg/dL. A similar lack of statin treatment efficacy for both outcomes was observed with high baseline phosphate levels (>5 mg/dL). In the 4D trial, we found a comparable but not significant trend towards losing treatment efficacy in presence of high serum phosphate levels for both outcomes. Conclusions: Our results demonstrated the limited treatment efficacy of statins in dialysis patients in the presence of hyperphosphatemia.

Platycodin D enhances LDLR expression and LDL uptake via down-regulation of IDOL mRNA in hepatic cells

The root of Platycodon grandiflorum (PG) has long been used as a traditional herbal medicine in Asian country. Platycondin D (PD), triterpenoid saponin that is a main constituent of PG, exhibits various biological activities such as anti-inflammatory, anti-oxidant, anti-diabetic, and anti-cancer effects. A previous study showed that PD had cholesterol-lowering effects in mice that develop hypercholesterolemia, but the underlying molecular mechanisms have not been elucidated during the last decade. Here, we demonstrated that both PG and PD markedly increased levels of cell surface low-density lipoprotein receptor (LDLR) by down-regulation of the E3 ubiquitin ligase named inducible degrader of the LDLR (IDOL) mRNA, leading to the enhanced uptake of LDL-derived cholesterol (LDL-C) in hepatic cells. Furthermore, cycloheximide chase analysis and in vivo ubiquitination assay revealed that PD increased the half-life of LDLR protein by reducing IDOL-mediated LDLR ubiquitination. Finally, we demonstrated that treatment of HepG2 cells with simvastatin in combination with PG and PD had synergistic effects on the improvement of LDLR expression and LDL-C uptake. Together, these results provide the first molecular evidence for anti-hypercholesterolemic activity of PD and suggest that PD alone or together with statin could be a potential therapeutic option in the treatment of atherosclerotic cardiovascular disease.

Regulation of hepatic hydroxy methyl glutarate - CoA reductase for controlling hypercholesterolemia in rats

Hypercholesterolemia is a major risk factor upon developing cardiovascular diseases. This study is aiming to investigate the inhibition role of quercetin on hydroxy methyl glutarate - CoA reductase activity and its gene for attenuating hypercholesterolemia. The kinetic characteristics of HMG-CoA reductase activity were evaluated on extracellular rat liver microsomes. For studying the effect of quercetin by inducing hypercholesterolemia rats by Tyloxapol (i.v.). In addition, rats were treated with different doses of quercetin according to the inhibition constant of this inhibitor. Our results showed that in quercetin rats groups plasma cholesterol, triglycerides, LDL -cholesterol and total lipids levels and hepatic (TBARS) level were significantly decreased as compared with negative control. However, plasma HDL level, hepatic total thiol level, catalase activity and total protein level significantly increased groups as compared with negative control. In addition, HMG-CoA reductase activity was decreased in quercetin groups and this confirmed in gene expression that these groups caused downregulation for HMG-CoA reductase. However, LDL receptor (LDLr) gene expression was upregulated by quercetin. Moreover, histopathological examination of rat liver showed the ameliorative effect of quercetin on hypercholesterolemic effect of triton. In conclusion, quercetin may consider as a new saving candidate for the future development of hypocholesterolemia agents.

Influence of Extracting Solvent on Pharmacological Activity and Cytotoxicity of Polygonum minus, a Commonly Consumed Herb in Southeast Asia

Objective:

To investigate the antihyperlipidemic, antioxidant, and cytotoxic effect of aqueous and methanol extract of leaves of Polygonum minus.

Materials and Methods:

Acute antihyperlipidemic effect was studied on chemically induced hyperlipidemic rat model. Treated groups received aqueous and methanol extract of leaves of P. minus respectively (1000 mg/kg; oral) whereas standard treated group received atorvastatin (60 mg/kg; oral) for 3 consecutive days. Blood samples were collected at fixed intervals for lipid profile analysis. Antioxidant effects were studied using 1,1-diphenyl-2-picrylhydrazyl, 2,2-azinobis 3-ethylbenzothiazoline 6-sulfonate, and ferric reducing antioxidant power assays. The total flavonoids content and total phenolic contents were also estimated. Cytotoxicity of both extracts was studied on one normal and three cancer cell lines using 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay method.

Results:

The methanol extract showed significant reduction in total cholesterol (P < 0.001), triglycerides (P < 0.01), LDL (P < 0.05), VLDL (P < 0.01), atherogenic index (P < 0.001), and elevation of HDL (P < 0.05) levels than the aqueous extract. Similarly, the antioxidant investigations also demonstrated that the methanol extract had higher antioxidant capacity than aqueous extract. Both extracts were not toxic to normal (EA.hy926) as well as to cancer (HCT116, HT29, and HeLa) cells. Significant correlation was demonstrated between total phenolic and total flavonoids contents with the antioxidant activity but not with the antihyperlipidemic effect, suggesting other groups of chemical constituents may be mainly responsible for the antihyperlipidemic effect of this plant.

Conclusion:

The study demonstrated that the presence and extent of bioactivities are influenced by solvents used for extraction. This study confirmed the antihyperlipidemic effect of leaves of P. minus in acute hyperlipidemic rat model.

SUMMARY

Polygonum minus is an herbaceous flowering plant.

This plant possess high amount of phenolics and flavonoids

This study focused on the antioxidant, cytotoxicity and antihyperlipidemic effect of aqueous and methanol extracts of leaves of P. minus

The extracts possess significant antioxidant activity and antihyperlipidemic activity but they are not toxic to normal and cancer cells tested.

The antioxidant activity is well correlated with phenolic and flavonoids contents but the antihyperlipidemic activity is not correlated with antioxidant effect.

Abbreviations used: CVDs: Cardiovascular diseases, LDL: Low-density lipoprotein, DDPH: 1,1-Diphenyl-2-picrylhydrazyl radical, TPTZ: 2,4,6,-tris(1-pyridyl)-5-triazine, ABTS: 2,2’-Azino-di-[3-ethylbenzthiazoline Sulfonate], HDL: High-density lipoprotein, VLDL: Very low-density lipoprotein, TC: Total cholesterol, TG: Triglycerides, EC50: Half maximal effective concentration, LD50: Median lethal dose.

Effect of extraction solvents and plant parts used on the antihyperlipidemic and antioxidant effects of Garcinia atroviridis: a comparative study

BACKGROUND

Garcinia atroviridis is a seasonal fruit plant found in many parts of South East Asia. The fruit rind is used in cooking and traditionally consumed for various reasons, including to lower blood cholesterol. A comparative study was undertaken to investigate the influence of extraction solvents and plant parts used on the lipid-lowering and antioxidant activities of Garcinia atroviridis.

RESULTS

Aqueous extracts showed better antihyperlipidemic activity than the methanol extracts. Aqueous extract of ripe fruit showed the most potent antihyperlipidemic activity, comparable to that of atorvastatin. It significantly reduced the total cholesterol (P < 0.05), triglycerides (P < 0.01), low-density lipoprotein (P < 0.01), very-low-density lipoprotein (P < 0.01) and atherogenic index (P < 0.01). In contrast, antioxidant activities of methanol extracts of all parts of G. atroviridis were higher than their respective aqueous extracts, whereby the stem and leaves extracts showed better antioxidant activities than the fruits.

CONCLUSION

Aqueous and methanol extracts of G. atroviridis showed higher antihyperlipidemic and antioxidant effects, respectively. Total phenolic and flavonoid contents showed significant correlations with antioxidant but not with antihyperlipidemic activities, indicating the involvement of other compounds. Contrary to the traditional belief, the present findings suggest that the fruit has higher antihyperlipidemic potential than the fruit rind.

Effects of a farnesoid X receptor antagonist on hepatic lipid metabolism in primates

We aimed to elucidate the mechanism underlying the anti-dyslipidemic effect of compound-T3, a farnesoid X receptor antagonist, by investigating its effects on hepatic lipid metabolism in non-human primates. We administered lipid-lowering drugs for 7 days to cynomolgus monkeys receiving a high-fat diet, and subsequently measured the levels of lipid parameters in plasma, feces, and hepatic tissue fluids. Compound-T3 (0.3 and 3mg/kg p.o.) significantly decreased the plasma levels of non-high-density lipoprotein (non-HDL) cholesterol and apolipoprotein B in a dose-dependent manner. It also decreased the mRNA levels of hepatic small heterodimer partner-1, induced the mRNA expression of hepatic cholesterol 7α-hydroxylase, reduced hepatic cholesterol and triglyceride levels, increased fecal bile acid excretion, and upregulated the expression of hepatic low-density lipoprotein (LDL) receptor. Furthermore, compound-T3 significantly increased plasma HDL cholesterol and apolipoprotein A-I levels. The mRNA expression levels of hepatic apolipoprotein A-I tended to increase after compound-T3 treatment. Compound-T3 also induced accumulation of hepatic bile acids and decreased the mRNA expression levels of the hepatic bile acid export pump. The effects of cholestyramine (300mg/kg p.o.) on the plasma and hepatic lipid parameters were similar to those of compound-T3, and it increased fecal bile acid levels without causing accumulation of hepatic bile acids. These findings suggest that LDL receptor-mediated hepatic LDL incorporation due to cholesterol catabolism catalyzed by cholesterol 7α-hydroxylase decreases plasma non-HDL cholesterol levels. Upregulation of hepatic apolipoprotein A-I mRNA expression may partially contribute to the increase in HDL cholesterol levels mediated by compound-T3.

Chemical properties of a polysaccharide purified from solid-state fermentation of Auricularia auricular and its biological activity as a hypolipidemic agent

A water-soluble crude polysaccharide was extracted by hot water from Auricularia auricular mycelium grown under solid-state fermentation (SSF). The crude polysaccharide was purified by DEAE Sephadex A-50 and Sephadex G-200 chromatography. Fourier transform infrared spectroscopy and nuclear magnetic resonance ((1) H NMR) spectroscopy were used to investigate the structure of the purified A. auricular polysaccharide (AAP-I) and revealed that it is α-glycosidically linked. After 14 and 28 days of AAP-I orally administered, the AAP-I significantly decreased the levels of total cholesterol, triglyceride, and low-density lipoprotein cholesterol in mice in which hyperlipidemia had been induced by a high fat diet (P < 0.05). The results revealed that AAP-I from SSF of A. auricular mycelium possesses potent hypolipidemic properties. The polysaccharide may be useful as a functional food additive and a hypolipidemic agent.

Quercetin up-regulates LDL receptor expression in HepG2 cells

Quercetin, an abundant flavonol found in fruits and vegetable, has been implicated in lowering the risk of cardiovascular disease that is often associated with high plasma levels of low density lipoprotein (LDL) cholesterol. Here we investigated whether quercetin could modulate the expression of LDL receptors (LDLR) in HepG2 cells and the possible underlying mechanisms to exert quercetin's effects. We found that quercetin was able to induce LDLR expression with at least a 75 µ m concentration, which was accompanied by an increase in nuclear sterol regulatory element binding protein 2 (SREBP2). This effect was mediated by activation of c-jun-N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) signalling pathways as implicated by experiments using chemical inhibitors of each pathway. When cells were challenged with protein synthesis inhibitors in quercetin-activated LDLR transcription, LDL mRNA levels were not significantly affected by cycloheximide but puromycin abolished quercetin-induced LDLR transcription. Taken together, we conclude that quercetin can initiate LDLR transcription by enhancing SREBP2 processing, but new protein synthesis might be necessary to exert a maximum effect of quercetin in the up-regulation of the LDLR gene. Our findings demonstrate that quercetin strongly up-regulated LDLR gene expression, which might elicit hypolipidemic effects by increasing the clearance of circulating LDL cholesterol levels from the blood.

Functional polymers as therapeutic agents: concept to market place

Biologically active synthetic polymers have received considerable scientific interest and attention in recent years for their potential as promising novel therapeutic agents to treat human diseases. Although a significant amount of research has been carried out involving polymer-linked drugs as targeted and sustained release drug delivery systems and prodrugs, examples on bioactive polymers that exhibit intrinsic therapeutic properties are relatively less. Several appealing characteristics of synthetic polymers including high molecular weight, molecular architecture, and controlled polydispersity can all be utilized to discover a new generation of therapies. For example, high molecular weight bioactive polymers can be restricted to gastrointestinal tract, where they can selectively recognize, bind, and remove target disease causing substances from the body. The appealing features of GI tract restriction and stability in biological environment render these polymeric drugs to be devoid of systemic toxicity that are generally associated with small molecule systemic drugs. The present article highlights recent developments in the rational design and synthesis of appropriate functional polymers that have resulted in a number of promising polymer based therapies and biomaterials, including some marketed products.

Identification of two herbal compounds with potential cholesterol-lowering activity

Low-density lipoprotein receptor (LDLR) plays a pivotal role in the control of plasma LDL-cholesterol level. This occurs predominantly at the transcriptional level through two gene regulation elements, named SRE: sterol-responsive element and SIRE: sterol-independent responsive element. We have developed a high-throughput screening using LDLR promoter activation-based assay to search for cholesterol-lowering compounds from a Chinese herb-based natural compound library. With this approach, we identified two compounds, named Daphnetoxin and Gniditrin, from Chinese herb Daphne giraldii Nitsche, which could activate LDLR promoter. Characterization of these compounds showed that they increased the level of LDLR mRNA and consequently up-regulate LDLR expression. The structures of these compounds are different from well-known LDLR promoter activating compounds such as GW707. The results suggested that these herbal compounds could represent good candidates for development of new classes of cholesterol-lowering drugs.

The biology and chemistry of hyperlipidemia

Coronary arterial diseases are responsible for more deaths than all other associated causes combined. Elevated serum cholesterol levels leading to atherosclerosis can cause coronary heart disease (CHD). Reduction in serum cholesterol levels reduces the risk for CHD, substantially. Medicinal chemists all around the world have been designing, synthesizing, and evaluating a variety of new bioactive molecules for lowering lipid levels. This review summarizes the disorders associated with elevation of lipids in blood and the current strategies to control them. The emphasis has been laid in particular on the new potential biological targets and the possible treatments as well as the current ongoing research status in the field of lipid lowering agents.

The medicinal plant goldenseal is a natural LDL-lowering agent with multiple bioactive components and new action mechanisms

Our previous studies have identified berberine (BBR), an alkaloid isolated from the Chinese herb huanglian, as a unique cholesterol-lowering drug that upregulates hepatic low density lipoprotein receptor (LDLR) expression through a mechanism of mRNA stabilization. Here, we demonstrate that the root extract of goldenseal, a BBR-containing medicinal plant, is highly effective in upregulation of liver LDLR expression in HepG2 cells and in reducing plasma cholesterol and low density lipoprotein cholesterol (LDL-c) in hyperlipidemic hamsters, with greater activities than the pure compound BBR. By conducting bioassay-driven semipurifications, we demonstrate that the higher potency of goldenseal is achieved through concerted actions of multiple bioactive compounds in addition to BBR. We identify canadine (CND) and two other constituents of goldenseal as new upregulators of LDLR expression. We further show that the activity of BBR on LDLR expression is attenuated by multiple drug resistance-1 (MDR1)-mediated efflux from liver cells, whereas CND is resistant to MDR1. This finding defines a molecular mechanism for the higher activity of CND than BBR. We also provide substantial evidence to show that goldenseal contains natural MDR1 antagonist(s) that accentuate the upregulatory effect of BBR on LDLR mRNA expression. These new findings identify goldenseal as a natural LDL-c-lowering agent, and our studies provide a molecular basis for the mechanisms of action.

Pharmacological interference with intestinal bile acid transport reduces plasma cholesterol in LDL receptor/apoE deficiency

Reduction of plasma cholesterol by statins is fundamental to prevent coronary heart disease. Such therapy is often sub-optimal, however, particularly in patients with reduced LDL receptors (familial hypercholesterolemia), and novel or adjuvant therapies are therefore warranted. Cholesterol elimination is profoundly influenced by the rate of its conversion to bile acids (BA), regulated by the enzyme Cyp7a1. Induced fecal loss of BA by resin treatment reduces plasma cholesterol, presumably through induction of hepatic LDL receptors (LDLR). We here describe the effect of PR835, a drug belonging to a new class of lipid-lowering agents that inhibit the Slc10a2 protein, the intestinal transporter responsible for active uptake of BA. Treatment reduced plasma cholesterol by 40% in mice devoid of both the LDLR and its ligand, apoE, while triglycerides and HDL cholesterol were unchanged. Cyp7a1 enzyme activity and mRNA were induced several-fold, and hepatic HMG CoA reductase mRNA increased, mirroring an induced synthesis of BA and cholesterol. The addition of a statin potentiated the effect, leading to reductions of plasma total and LDL cholesterol by 64% and 70%, respectively. These effects could not be attributed to induction of other known hepatic lipoprotein receptors and indicate the presence of new points of targeting in lipid-lowering therapy.

Therapy to reduce risk of coronary heart disease

Recent primary and secondary intervention studies have shown that reduction of low-density lipoprotein cholesterol (LDL-C) with statins significantly reduced coronary heart disease (CHD) morbidity and mortality. However, many patients with dyslipidemia who have or are at risk for CHD do not reach target LDL-C goals. The recently updated National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III guidelines identify a group of patients at very high risk for CHD for more aggressive LDL-C reduction and reaffirm the importance of high-density lipoprotein cholesterol (HDL-C) by raising the categorical threshold to 40 mg/dl. Lipid-lowering therapy needs to be more aggressive in both primary and secondary prevention settings, and therapy should be considered to increase HDL-C as well as lower LDL-C in order to improve patient outcomes. Both combination therapy and the next generation of statins may provide improved efficacy across the dyslipidemia spectrum.

Synergistic activation of human LDL receptor expression by SCAP ligand and cytokine oncostatin M

OBJECTIVE

A recent study identified a new class of compounds designated as the sterol-regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) ligands that putatively bind to SCAP, leading to increased LDL receptor (LDLR) expression. In this study, we examined the effects of SCAP ligand GW707 in comparison with lovastatin and cytokine oncostatin M (OM) on the regulation of LDLR expression in cultured HepG2 cells.

METHODS AND RESULTS

Our studies uncovered several new features that distinguish SCAP ligand from lovastatin, a classic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, and from OM, which utilize an SREBP-independent regulatory pathway. We show that the induction of LDLR mRNA expression by GW707 is not affected by intracellular cholesterol but is completely abolished by blocking de novo protein synthesis. Moreover, the effects of GW707 but not lovastatin on LDLR promoter activity, mRNA expression, and uptake of 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanin perchlorate-LDL are markedly enhanced by OM. We further demonstrate that the amounts of the mature form of SREBP-2 translocated to the nucleus under GW707 treatment are increased by costimulating cells with OM.

CONCLUSIONS

Our studies provide the first evidence that higher levels of LDLR expression and function can be achieved through simultaneous stimulation of the SREBP-dependent and SREBP-independent pathways, suggesting a strategy to develop an adjunct therapeutic intervention utilizing both pathways.