t0901317 and Atherosclerosis

The Liver X Receptors (LXRs) are oxysterol-activated transcription factors that upregulate a suite of genes that together promote coordinated mobilization of excess cholesterol from cells and from the body. The LXRs, like other nuclear receptors, are anti-inflammatory, inhibiting signal-dependent induction of pro-inflammatory genes by nuclear factor-κB, activating protein-1, and other transcription factors. Synthetic LXR agonists have been shown to ameliorate atherosclerosis and a wide range of inflammatory disorders in preclinical animal models. Although this has suggested potential for application to human disease, systemic LXR activation is complicated by hepatic steatosis and hypertriglyceridemia, consequences of lipogenic gene induction in the liver by LXRα. The past several years have seen the development of multiple advanced LXR therapeutics aiming to avoid hepatic lipogenesis, including LXRβ-selective agonists, tissue-selective agonists, and transrepression-selective agonists. Although several synthetic LXR agonists have made it to phase I clinical trials, none have progressed due to unforeseen adverse reactions or undisclosed reasons. Nonetheless, several sophisticated pharmacologic strategies, including structure-guided drug design, cell-specific drug targeting, as well as non-systemic drug routes have been initiated and remain to be comprehensively explored. In addition, recent studies have identified potential utility for targeting the LXRs during therapy with other agents, such as glucocorticoids and rexinoids. Despite the pitfalls encountered to date in translation of LXR agonists to human disease, it appears likely that this accelerating field will ultimately yield effective and safe applications for LXR targeting in humans.

Topics: Animals; Atherosclerosis; Benzoates; Benzylamines; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Inflammation; Liver X Receptors; Models, Biological; Molecular Targeted Therapy; Sulfonamides

The Liver X Receptor (LXR) alpha and beta isoforms are members of the type II nuclear receptor family which function as obligate heterodimers with the Retinoid X Receptor (RXR). Upon agonist binding, the DNA Binding Domain (DBD) of LXR interacts with LXR response elements on target genes to initiate transcription. A number of genes have been shown to be modulated by LXR function, including the ATP-binding cassette transporter A1 (ABCA1). ABCA1 is involved in the process of reverse cholesterol transport (RCT) from macrophages in atherosclerotic plaques to high-density lipoproteins (HDL) in the plasma. Both homozygous and heterozygous mutations in ABCA1 result in conditions characterised by decreased levels of HDL and an earlier onset of atherosclerosis. A number of other genes are upregulated by LXR activation which would be expected to have either pro- or anti-atherogenic effects. One such target gene is sterol regulatory element binding protein-1c (SREBP-1c), which is involved in the process of lipogenesis leading to increased levels of triglycerides which are pro-atherogenic. The complexity of LXR responses, however, makes it difficult to extrapolate the 'positive' or 'negative' effects of each target gene in isolation to a conclusion as to the outcome in humans when all target genes are being modulated in concert. This review will cover the structural features and associated biological data of non-steroidal LXR modulators claimed for the treatment of cardiovascular disease, as well as highlighting preferred compounds where this information can be discerned. In addition to this patent information a précis of literature data relevant to the utility of specific compounds in the treatment of cardiovascular disease will be given where available.

Topics: Acetyl-CoA Carboxylase; Animals; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; DNA-Binding Proteins; Fatty Acid Synthases; Humans; Hydrocarbons, Fluorinated; Liver X Receptors; Orphan Nuclear Receptors; Osteopontin; Receptors, Cytoplasmic and Nuclear; Sterol Regulatory Element Binding Protein 1; Sulfonamides; Thromboplastin

Targeting macrophage but not hepatocyte liver X receptors (LXRs) can reduce atherosclerosis without effect on hepatic lipogenesis. In this study, we encapsulated LXR ligands with D-Nap-GFFY to form a nanofibre hydrogel (D-Nap-GFFY-T0901317 or GFFY-T0901317) and determined its effect on atherosclerosis, hepatic lipogenesis and the underlying mechanisms involved.. D-Nap-GFFY-T0901317 was subcutaneously injected to proatherogenic diet-fed apoE-deficient (Apoe. Our study demonstrates that D-Nap-GFFY-T0901317 reduces atherosclerosis without effect on hepatic lipogenesis by targeting macrophage LXRs selectively, indicating its potential application for atherosclerosis treatment.

Topics: Animals; Atherosclerosis; Hydrocarbons, Fluorinated; Hydrogels; Lipogenesis; Liver; Liver X Receptors; Macrophages; Mice; Mice, Inbred C57BL; Sulfonamides

Despite advances in healthcare, cardiovascular disease (CVD) remains the leading cause of death in the United States. Elevated levels of plasma cholesterol are highly predictive of CVD and stroke and are the principal driver of atherosclerosis. Unfortunately, current cholesterol lowering agents, such as statins, are not known to reverse atherosclerotic disease once it has been established. In preclinical models, agonists of nuclear receptor, LXR, have been shown to reduce and reverse atherosclerosis. Phytosterols are bioactive non-cholesterol sterols that act as LXR agonists and regulate cholesterol metabolism and transport. We hypothesized that stigmasterol would act as an LXR agonist and alter intestinal cholesterol secretion to promote cholesterol elimination. Mice were fed a control diet, or a diet supplemented with stigmasterol (0.3% w/w) or T0901317 (0.015% w/w), a known LXR agonist. In this experiment we analyzed the sterol content of bile, intestinal perfusate, plasma, and feces. Additionally, the liver and small intestine were analyzed for relative levels of transcripts known to be regulated by LXR. We observed that T0901317 robustly promoted cholesterol elimination and acted as a strong LXR agonist. Stigmasterol promoted transintestinal cholesterol secretion through an LXR-independent pathway.

Topics: Animals; Atherosclerosis; Bile; Bile Ducts; Cholesterol; Female; Hydrocarbons, Fluorinated; Intestine, Small; Liver; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Orphan Nuclear Receptors; Phytosterols; Sterols; Stigmasterol; Sulfonamides

Liver X Receptor (LXR) is a potential drug target for atherosclerosis. One of the major challenges in taking LXR modulators to the clinic is steatosis. It was reported that sterol LXR agonists selectively activate LXR in the intestine and macrophage cells rather than in the liver. We hypothesize that sterol LXR agonists may selectively inhibit atherosclerosis without causing hepatic lipogenesis. Thus, based on LXR structure, 12 sterol compounds were designed and tested in a dual-luciferase reporter gene experiment. It was confirmed that compounds 4 and 6 were LXR agonists. Further experiments demonstrated that compounds 4 and 6 inhibit the formation of macrophage foam cells without inducing triglyceride accumulation in either hepatocytes or adipocytes. In vivo studies demonstrated that compound 4 promotes reverse cholesterol transport without inducing hepatic lipogenesis. Thus, we report that these compounds with sterol scaffolds can be promising leads for the treatment of atherosclerosis without inducing steatosis.

Topics: 3T3-L1 Cells; Animals; Atherosclerosis; Cell Differentiation; Dose-Response Relationship, Drug; Drug Discovery; HEK293 Cells; Hep G2 Cells; Hepatocytes; Humans; Lipogenesis; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Models, Molecular; Molecular Structure; RAW 264.7 Cells; Sterols; Structure-Activity Relationship

Targeting at enhancing reverse cholesterol transport (RCT) is apromising strategy for treating atherosclerosis via infusion of reconstitute high density lipoprotein (HDL) as cholesterol acceptors or increase of cholesterol efflux by activation of macrophage liver X receptors (LXRs). However, systemic activation of LXRs triggers excessive lipogenesis in the liver and infusion of HDL downregulates cholesterol efflux from macrophages. Here we describe an enlightened strategy using phospholipid reconstituted apoA-I peptide (22A)-derived synthetic HDL (sHDL) to deliver LXR agonists to the atheroma and examine their effect on atherosclerosis regression in vivo. A synthetic LXR agonist, T0901317 (T1317) was encapsulated in sHDL nanoparticles (sHDL-T1317). Similar to the T1317 compound, the sHDL-T1317 nanoparticles upregulated the expression of ATP-binding cassette transporters and increased cholesterol efflux in macrophages in vitro and in vivo. The sHDL nanoparticles accumulated in the atherosclerotic plaques of ApoE-deficient mice. Moreover, a 6-week low-dose LXR agonist-sHDL treatment induced atherosclerosis regression while avoiding lipid accumulation in the liver. These findings identify LXR agonist loaded sHDL nanoparticles as a promising therapeutic approach to treat atherosclerosis by targeting RCT in a multifaceted manner: sHDL itself serving as both a drug carrier and cholesterol acceptor and the LXR agonist mediating upregulation of ABC transporters in the aorta.

Topics: Animals; Atherosclerosis; Cell Line; Drug Delivery Systems; Hydrocarbons, Fluorinated; Lipogenesis; Lipoproteins, HDL; Liver; Liver X Receptors; Mice, Inbred C57BL; Models, Biological; Nanoparticles; Plaque, Atherosclerotic; Sulfonamides

Macrophage-derived foam-cell formation plays a crucial role in the development of atherosclerosis, and liver X receptor alpha (LXRα) is a key regulator of lipid metabolism in macrophages. Homocysteine (Hcy) is an independent risk factor of atherosclerosis; however, the regulation of lipid metabolism and role of LXRα induced by Hcy in macrophages is still unknown. The present study aimed to investigate the potential role of Hcy in disordered lipid metabolism and atherosclerotic lesions, especially the effects of Hcy on cholesterol efflux in macrophages and the possible mechanisms.. In vitro, lipid accumulation and cholesterol efflux were evaluated in THP-1 macrophages with Hcy intervention. Real-time quantitative PCR and western blot analyses were used to assess mRNA and protein levels. In vivo, atherosclerotic lesions and lipid profiles were evaluated by methionine diet-induced hyperhomocysteinemia (HHcy) in ApoE. Hcy promoted lipid accumulation and inhibited cholesterol efflux in THP-1 macrophages. HHcy mice showed increased lesion area and lipid accumulation in plaque. Both studies in vitro and in vivo showed decreased expression of ATP binding cassette transporter A1 (ABCA1) and G1 (ABCG1). T0901317 treatment increased ABCA1 and ABCG1 levels; reversed macrophage-derived foam-cell formation in THP-1 macrophages and reduced atherosclerotic lesions in ApoE. Inhibition of LXRα-mediated ABCA1/ABCG1-dependent cholesterol efflux from macrophages is a novel mechanism in Hcy-accelerated atherosclerosis.

Topics: Animals; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; Cell Line; Cholesterol; Foam Cells; Homocysteine; Humans; Hydrocarbons, Fluorinated; Lipid Metabolism; Liver X Receptors; Macrophages; Male; Mice, Knockout, ApoE; Plaque, Atherosclerotic; Sulfonamides

Macrophages play pivotal roles in the progression and regression of atherosclerosis. Accumulating evidence suggests that macrophage polarization into an anti-inflammatory M2 state is a key characteristic of atherosclerotic plaques undergoing regression. However, the molecular mechanisms underlying this potential association of the M2 polarization with atherosclerosis regression remain poorly understood. Further, human genetic factors that facilitate these anti-atherogenic processes remain largely unknown. We report that the transcription factor MafB plays pivotal roles in promoting macrophage M2 polarization. Further, MafB promotes cholesterol efflux from macrophage foam cells by directly up-regulating its key cellular mediators. Notably, MafB expression is significantly up-regulated in response to various metabolic and immunological stimuli that promote macrophage M2 polarization or cholesterol efflux, and thereby MafB mediates their beneficial effects, in both liver x receptor (LXR)-dependent and independent manners. In contrast, MafB is strongly down-regulated upon elevated pro-inflammatory signaling or by pro-inflammatory and pro-atherogenic microRNAs, miR-155 and miR-33. Using an integrative systems biology approach, we also revealed that M2 polarization and cholesterol efflux do not necessarily represent inter-dependent events, but MafB is broadly involved in both the processes. These findings highlight physiological protective roles that MafB may play against atherosclerosis progression.

Topics: Animals; Atherosclerosis; Base Sequence; Biological Transport; Cell Differentiation; Cholesterol; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Interleukin-10; Interleukin-4; Liver X Receptors; Macrophages; MafB Transcription Factor; Male; Mice; Mice, Transgenic; MicroRNAs; Plaque, Atherosclerotic; Primary Cell Culture; RAW 264.7 Cells; Signal Transduction; Sulfonamides; THP-1 Cells

Macrophages play a central role in atherosclerosis development and progression, hence, targeting macrophage activity is considered an attractive therapeutic. Recently, we documented nanomedicinal delivery of the anti-inflammatory compound prednisolone to atherosclerotic plaque macrophages in patients, which did however not translate into therapeutic efficacy. This unanticipated finding calls for in-depth screening of drugs intended for targeting plaque macrophages.. We evaluated the effect of several candidate drugs on macrophage activity, rating overall performance with respect to changes in cytokine release, oxidative stress, lipid handling, endoplasmic reticulum (ER) stress, and proliferation of macrophages. Using this in vitro approach, we observed that the anti-inflammatory effect of prednisolone was counterbalanced by multiple adverse effects on other key pathways. Conversely, pterostilbene, T0901317 and simvastatin had an overall anti-atherogenic effect on multiple pathways, suggesting their potential for liposomal delivery.. This dedicated assay setup provides a framework for high-throughput assessment. Further in vivo studies are warranted to determine the predictive value of this macrophage-based screening approach and its potential value in nanomedicinal drug development for cardiovascular patients.

Topics: Animals; Anti-Inflammatory Agents; Atherosclerosis; Cell Proliferation; Cytokines; Endoplasmic Reticulum Stress; High-Throughput Screening Assays; Humans; Hydrocarbons, Fluorinated; Inflammation; Inflammation Mediators; Lipid Metabolism; Lipopolysaccharides; Macrophage Activation; Macrophages; Mice; Mice, Inbred C57BL; NF-kappa B; Oxidative Stress; Plaque, Atherosclerotic; Prednisolone; RAW 264.7 Cells; Reactive Oxygen Species; Signal Transduction; Simvastatin; Stilbenes; Sulfonamides; Transfection

A novel series of 1,3-bistrifluoromethylcarbinol derivatives that act as liver X receptor (LXR) β-selective agonists was discovered. Structure-activity relationship studies led to the identification of molecule 62, which was more effective (Emax) and selective toward LXRβ than T0901317 and GW3965. Furthermore, 62 decreased LDL-C without elevating the plasma TG level and significantly suppressed the lipid-accumulation area in the aortic arch in a Bio F1B hamster fed a diet high in fat and cholesterol. We demonstrated that our LXRβ agonist would be potentially useful as a hypolipidemic and anti-atherosclerotic agent. In this manuscript, we report the design, synthesis and pharmacology of 1,3-bistrifluoromethylcarbinol derivatives.

Topics: Animals; Atherosclerosis; Benzoates; Benzylamines; Cricetinae; Drug Design; Humans; Hydrocarbons, Fluorinated; Hypolipidemic Agents; In Vitro Techniques; Lipid Metabolism; Liver; Liver X Receptors; Male; Methanol; Mice; Orphan Nuclear Receptors; Structure-Activity Relationship; Sulfonamides

Liver X receptor (LXR) agonists exert potent antiatherosclerotic actions but simultaneously induce excessive triglyceride (TG) accumulation in the liver. To obtain a detailed insight into the underlying mechanism of hepatic TG accumulation, we used a novel computational modeling approach called analysis of dynamic adaptations in parameter trajectories (ADAPT). We revealed that both input and output fluxes to hepatic TG content are considerably induced on LXR activation and that in the early phase of LXR agonism, hepatic steatosis results from only a minor imbalance between the two. It is generally believed that LXR-induced hepatic steatosis results from increased de novo lipogenesis (DNL). In contrast, ADAPT predicted that the hepatic influx of free fatty acids is the major contributor to hepatic TG accumulation in the early phase of LXR activation. Qualitative validation of this prediction showed a 5-fold increase in the contribution of plasma palmitate to hepatic monounsaturated fatty acids on acute LXR activation, whereas DNL was not yet significantly increased. This study illustrates that complex effects of pharmacological intervention can be translated into distinct patterns of metabolic regulation through state-of-the-art mathematical modeling.

Topics: Animals; Atherosclerosis; Computer Simulation; Fatty Acids, Nonesterified; Fatty Liver; Hydrocarbons, Fluorinated; Lipogenesis; Lipoproteins, VLDL; Liver; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Models, Biological; Orphan Nuclear Receptors; PPAR gamma; Sulfonamides; Systems Biology; Triglycerides

Activation of liver X receptor (LXR) inhibits atherosclerosis but induces hypertriglyceridemia. In vitro, it has been shown that mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor synergizes LXR ligand-induced macrophage ABCA1 expression and cholesterol efflux. In this study, we determined whether MEK1/2 (U0126) and LXR ligand (T0901317) can have a synergistic effect on the reduction of atherosclerosis while eliminating LXR ligand-induced fatty livers and hypertriglyceridemia. We also set out to identify the cellular mechanisms of the actions.. Wild-type mice were used to determine the effect of U0126 on a high-fat diet or high-fat diet plus T0901317-induced transient dyslipidemia and liver injury. ApoE deficient (apoE(-/-)) mice or mice with advanced lesions were used to determine the effect of the combination of T0901317 and U0126 on atherosclerosis and hypertriglyceridemia. We found that U0126 protected animals against T0901317-induced transient or long-term hepatic lipid accumulation, liver injury, and hypertriglyceridemia. Meanwhile, the combination of T0901317 and U0126 inhibited the development of atherosclerosis in a synergistic manner and reduced advanced lesions. Mechanistically, in addition to synergistic induction of macrophage ABCA1 expression, the combination of U0126 and T0901317 maintained arterial wall integrity, inhibited macrophage accumulation in aortas and formation of macrophages/foam cells, and activated reverse cholesterol transport. The inhibition of T0901317-induced lipid accumulation by the combined U0126 might be attributed to inactivation of lipogenesis and activation of lipolysis/fatty acid oxidation pathways.. Our study suggests that the combination of mitogen-activated protein kinase kinase 1/2 inhibitor and LXR ligand can function as a novel therapy to synergistically reduce atherosclerosis while eliminating LXR-induced deleterious effects.

Topics: Animals; Aorta; Aortic Diseases; Apolipoproteins E; Atherosclerosis; Butadienes; Chemical and Drug Induced Liver Injury; Cholesterol; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Fatty Liver; Female; Foam Cells; Hep G2 Cells; Humans; Hydrocarbons, Fluorinated; Hypertriglyceridemia; Liver; Liver X Receptors; Male; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Nitriles; Orphan Nuclear Receptors; Protein Kinase Inhibitors; Signal Transduction; Sulfonamides

We previously reported that cholesterol-enriched macrophages excrete cholesterol into the extracellular matrix. A monoclonal antibody that detects cholesterol microdomains labels the deposited extracellular particles. Macro-phage deposition of extracellular cholesterol depends, in part, on ABCG1, and this cholesterol can be mobilized by HDL components of the reverse cholesterol transport process. The objective of the current study was to determine whether ABCA1 also contributes to macrophage deposition of extracellular cholesterol. ABCA1 functioned in extracellular cholesterol deposition. The liver X receptor agonist, TO901317 (TO9), an ABCA1-inducing factor, restored cholesterol deposition that was absent in cholesterol-enriched ABCG1(-/-) mouse macrophages. In addition, the ABCA1 inhibitor, probucol, blocked the increment in cholesterol deposited by TO9-treated wild-type macrophages, and completely inhibited deposition from TO9-treated ABCG1(-/-) macrophages. Lastly, ABCA1(-/-) macrophages deposited much less extracellular cholesterol than wild-type macrophages. These findings demonstrate a novel function of ABCA1 in contributing to macrophage export of cholesterol into the extracellular matrix.

Topics: Animals; Apolipoprotein A-I; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Cholesterol; Extracellular Matrix; Humans; Hydrocarbons, Fluorinated; Lipoproteins; Lipoproteins, HDL; Liver X Receptors; Macrophages; Mice; Orphan Nuclear Receptors; Probucol; Sulfonamides

One of the possible causes of enhanced atherosclerosis in patients with chronic kidney disease (CKD) is the accumulation of uremic toxins. Since macrophage foam cell formation is a hallmark of atherosclerosis, we examined the direct effect of indoxyl sulfate (IS), a representative uremic toxin, on macrophage function. Macrophages differentiated from THP-1 cells were exposed to IS in vitro. IS decreased the cell viability of THP-1 derived macrophages but promoted the production of inflammatory cytokines (IL-1β, IS 1.0 mM: 101.8 ± 21.8 pg/mL vs. 0 mM: 7.0 ± 0.3 pg/mL, TNF-α, IS 1.0 mM: 96.6 ± 11.0 pg/mL vs. 0 mM: 15.1 ± 3.1 pg/mL) and reactive oxygen species. IS reduced macrophage cholesterol efflux (IS 0.5 mM: 30.3% ± 7.3% vs. 0 mM: 43.5% ± 1.6%) and decreased ATP-binding cassette transporter G1 expression. However, lipid uptake into cells was not enhanced. A liver X receptor (LXR) agonist, T0901317, improved IS-induced production of inflammatory cytokines as well as reduced cholesterol efflux. In conclusion, IS induced inflammatory reactions and reduced cholesterol efflux in macrophages. Both effects of IS were improved with activation of LXR. Direct interactions of uremic toxins with macrophages may be a major cause of atherosclerosis acceleration in patients with CKD.

Topics: Atherosclerosis; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Cell Line, Tumor; Cell Survival; Cholesterol; Cytokines; Down-Regulation; Humans; Hydrocarbons, Fluorinated; Indican; Liver X Receptors; Macrophages; Orphan Nuclear Receptors; Reactive Oxygen Species; Renal Insufficiency, Chronic; Sulfonamides

Liver X receptor (LXR) activators decrease atherosclerosis in mice. LXR activators (1) directly upregulate genes involved in reverse cholesterol transport and (2) exert anti-inflammatory effects mediated by transrepression of nuclear factor-κB target genes. We investigated whether myeloid cell deficiency of ATP-binding cassette transporters A1 and G1 (ABCA1/G1), principal targets of LXR that promote macrophage cholesterol efflux and initiate reverse cholesterol transport, would abolish the beneficial effects of LXR activation on atherosclerosis.. LXR activator T0901317 substantially reduced inflammatory gene expression in macrophages lacking ABCA1/G1. Ldlr(-/-) mice were transplanted with Abca1(-/-)Abcg1(-/-) or wild-type bone marrow (BM) and fed a Western-type diet for 6 weeks with or without T0901317 supplementation. Abca1/g1 BM deficiency increased atherosclerotic lesion complexity and inflammatory cell infiltration into the adventitia and myocardium. T0901317 markedly decreased lesion area, complexity, and inflammatory cell infiltration in the Abca1(-/-)Abcg1(-/-) BM-transplanted mice. To investigate whether this was because of macrophage Abca1/g1 deficiency, Ldlr(-/-) mice were transplanted with LysmCreAbca1(fl/fl)Abcg1(fl/fl) or Abca1(fl/fl)Abcg1(fl/fl) BM and fed Western-type diet with or without the more specific LXR agonist GW3965 for 12 weeks. GW3965 decreased lesion size in both groups, and the decrease was more prominent in the LysmCreAbca1(fl/fl)Abcg1(fl/fl) group.. The results suggest that anti-inflammatory effects of LXR activators are of key importance to their antiatherosclerotic effects in vivo independent of cholesterol efflux pathways mediated by macrophage ABCA1/G1. This has implications for the development of LXR activators that lack adverse effects on lipogenic genes while maintaining the ability to transrepress inflammatory genes.

Topics: Animals; Anti-Inflammatory Agents; Aorta; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Benzoates; Benzylamines; Biological Transport; Bone Marrow Transplantation; Cholesterol; Cytokines; Disease Models, Animal; Female; Gene Expression Regulation; Hydrocarbons, Fluorinated; Inflammation Mediators; Lipopolysaccharides; Lipoproteins; Liver X Receptors; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardium; Orphan Nuclear Receptors; Receptors, LDL; Sulfonamides

Topics: Animals; Anti-Inflammatory Agents; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Benzoates; Benzylamines; Female; Hydrocarbons, Fluorinated; Lipoproteins; Liver X Receptors; Macrophages; Male; Orphan Nuclear Receptors; Receptors, LDL; Sulfonamides

LXRs have been of interest as targets for the treatment of atherosclerosis for over a decade. In recent years, LXR modulators have also garnered interest for potential use in the treatment of inflammation, Alzheimer's disease (AD), dermatological conditions, hepatic steatosis, and oncology. To date, no LXR modulator has successfully progressed beyond phase I clinical trials. In this Perspective, we summarize published medicinal chemistry efforts in the context of the available crystallographic data, druglikeness, and isoform selectivity. In addition, we discuss the challenges that need to be overcome before an LXR modulator can reach clinical use.

Topics: Anticholesteremic Agents; Atherosclerosis; Benzoates; Benzylamines; Binding Sites; Crystallography, X-Ray; Humans; Hydrocarbons, Fluorinated; Liver X Receptors; Models, Molecular; Molecular Structure; Orphan Nuclear Receptors; Protein Isoforms; Protein Structure, Tertiary; Sulfonamides

Increased physiological levels of oxysterols are major risk factors for developing atherosclerosis and cardiovascular disease. Lipid-loaded macrophages, termed foam cells, are important during the early development of atherosclerotic plaques. To pursue the hypothesis that ligand-based modulation of the nuclear receptor LXRα is crucial for cell homeostasis during atherosclerotic processes, we analysed genome-wide the action of LXRα in foam cells and macrophages. By integrating chromatin immunoprecipitation-sequencing (ChIP-seq) and gene expression profile analyses, we generated a highly stringent set of 186 LXRα target genes. Treatment with the nanomolar-binding ligand T0901317 and subsequent auto-regulatory LXRα activation resulted in sequence-dependent sharpening of the genome-binding patterns of LXRα. LXRα-binding loci that correlated with differential gene expression revealed 32 novel target genes with potential beneficial effects, which in part explained the implications of disease-associated genetic variation data. These observations identified highly integrated LXRα ligand-dependent transcriptional networks, including the APOE/C1/C4/C2-gene cluster, which contribute to the reversal of cholesterol efflux and the dampening of inflammation processes in foam cells to prevent atherogenesis.

Topics: Apoptosis; Atherosclerosis; Cell Line; Cells, Cultured; Cholesterol; Foam Cells; Gene Expression Regulation; Gene Regulatory Networks; Genetic Loci; Genetic Variation; Genome, Human; Humans; Hydrocarbons, Fluorinated; Ligands; Liver X Receptors; Macrophages; Orphan Nuclear Receptors; PPAR alpha; Signal Transduction; Sulfonamides; Transcription Initiation Site

Liver X receptors (LXRα and LXRβ) are important regulators of cholesterol and lipid metabolism, and their activation has been shown to inhibit cardiovascular disease and reduce atherosclerosis in animal models. Small molecule agonists of LXR activity are therefore of great therapeutic interest. However, the finding that such agonists also promote hepatic lipogenesis has led to the idea that hepatic LXR activity is undesirable from a therapeutic perspective. To investigate whether this might be true, we performed gene targeting to selectively delete LXRα in hepatocytes. Liver-specific deletion of LXRα in mice substantially decreased reverse cholesterol transport, cholesterol catabolism, and cholesterol excretion, revealing the essential importance of hepatic LXRα for whole body cholesterol homeostasis. Additionally, in a pro-atherogenic background, liver-specific deletion of LXRα increased atherosclerosis, uncovering an important function for hepatic LXR activity in limiting cardiovascular disease. Nevertheless, synthetic LXR agonists still elicited anti-atherogenic activity in the absence of hepatic LXRα, indicating that the ability of agonists to reduce cardiovascular disease did not require an increase in cholesterol excretion. Furthermore, when non-atherogenic mice were treated with synthetic LXR agonists, liver-specific deletion of LXRα eliminated the detrimental effect of increased plasma triglycerides, while the beneficial effect of increased plasma HDL was unaltered. In sum, these observations suggest that therapeutic strategies that bypass the liver or limit the activation of hepatic LXRs should still be beneficial for the treatment of cardiovascular disease.

Topics: Animals; Anticholesteremic Agents; Atherosclerosis; Bile Acids and Salts; Biological Transport; Cells, Cultured; Cholesterol; Feces; Female; Gene Knockout Techniques; Homeostasis; Hydrocarbons, Fluorinated; Lipid Metabolism; Lipoproteins; Liver; Liver X Receptors; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Transgenic; Organ Specificity; Orphan Nuclear Receptors; Particle Size; Sulfonamides; Triglycerides

The severity of atherosclerosis is primarily determined by overall lipid metabolism and the degree of inflammation present within the vessel wall. We evaluated the effects of T-0901317, a liver X receptor agonist, on the atherosclerosis process, and especially on the endothelial function in ApoE(-/-) mice.. ApoE(-/-) mice were treated with LXR agonist T-0901317 (1 μmol/L) for 6 weeks. ApoE(-/-) mice receiving T-0901317 were found to have markedly improved overall serum lipid profiles, albeit increased serum triglycerides. MRI imaging demonstrated that T-0901317 attenuated the atherosclerotic plaque burden in the aorta of ApoE(-/-) mice. Transmission electron microscopy and immunohistochemistry revealed attenuated ultrastructural changes as well as enhanced expression of the ATP-binding cassette transporter ABCA1. In addition, treatment with the LXR agonist improved the vasomotor function of atherosclerotic arteries, as assessed by KCl/norepinephrine-induced vasoconstrictive and acetylcholine-induced vasorelaxation functional assays. In vitro studies showed increased ABCG1, phospho-Akt and phospho-eNOS expression in ApoE(-/-) mice aorta endothelial cells (ECs) after T0901317 treatment.. The present study suggest that LXR agonists protect the endothelium against atherosclerotic insults by increasing ABCA1 and ABCG1 expression, and improve the endothelial-dependent vasomotor function probably by promoting Akt and eNOS phosphorylation.

Topics: Animals; Aorta, Thoracic; Apolipoproteins E; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Endothelium, Vascular; Hydrocarbons, Fluorinated; Lipids; Lipoproteins; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase Type III; Oncogene Protein v-akt; Orphan Nuclear Receptors; Plaque, Atherosclerotic; Sulfonamides; Vasoconstriction; Vasodilation

IL-5 stimulates production of T15/EO6 IgM antibodies that can block the uptake of oxidized low density lipoprotein by macrophages, whereas a deficiency in macrophage IL-5 expression accelerates development of atherosclerosis. Liver X receptors (LXRs) are ligand-activated transcription factors that can induce macrophage ABCA1 expression and cholesterol efflux, thereby inhibiting the development of atherosclerosis. However, it remains unknown whether additional mechanisms, such as the regulation of macrophage IL-5 expression, are related to the anti-atherogenic properties of LXR. We initially defined IL-5 expression in macrophages where the LXR ligand (T0901317) induced macrophage IL-5 protein expression and secretion. The overexpression of LXR increased, whereas its knockdown inhibited IL-5 expression. Furthermore, we found that LXR activation increased IL-5 transcripts, promoter activity, formation of an LXR·LXR-responsive element complex, and IL-5 protein stability. In vivo, we found that T0901317 increased IL-5 and total IgM levels in plasma and IL-5 expression in multiple tissues in wild type mice. In LDL receptor knock-out (LDLR(-/-)) mice, T0901317 increased IL-5 expression in the aortic root area. Taken together, our studies demonstrate that macrophage IL-5 is a target gene for LXR activation, and the induction of macrophage IL-5 expression can be related to LXR-inhibited atherosclerosis.

Topics: Animals; Aorta; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; Cell Line; Cholesterol; Gene Expression Regulation; Gene Knockdown Techniques; Hydrocarbons, Fluorinated; Immunoglobulin M; Interleukin-5; Liver X Receptors; Macrophages; Mice; Mice, Knockout; Orphan Nuclear Receptors; Response Elements; Sulfonamides

(18)F-Fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging of atherosclerosis in the clinic is based on preferential accumulation of radioactive glucose analog in atherosclerotic plaques. FDG-PET is challenging in mouse models due to limited resolution and high cost. We aimed to quantify accumulation of nonradioactive glucose metabolite, FDG-6-phosphate, in the mouse atherosclerotic plaques as a simple alternative to PET imaging.. Nonradioactive FDG was injected 30 minutes before euthanasia. Arteries were dissected, and lipids were extracted. The arteries were re-extracted with 50% acetonitrile-50% methanol-0.1% formic acid. A daughter ion of FDG-6-phosphate was quantified using liquid chromatography and mass spectrometry (LC/MS/MS). Thus, both traditional (cholesterol) and novel (FDG-6-phosphate) markers were assayed in the same tissue. FDG-6-phosphate was accumulated in atherosclerotic lesions associated with carotid ligation of the Western diet fed ApoE knockout mice (5.9 times increase compare to unligated carotids, p<0.001). Treatment with the liver X receptor agonist T0901317 significantly (2.1 times, p<0.01) reduced FDG-6-phosphate accumulation 2 weeks after surgery. Anti-atherosclerotic effects were independently confirmed by reduction in lesion size, macrophage number, cholesterol ester accumulation, and macrophage proteolytic activity.. Mass spectrometry of FDG-6-phosphate in experimental atherosclerosis is consistent with plaque inflammation and provides potential translational link to the clinical studies utilizing FDG-PET imaging.

Topics: Animals; Apolipoproteins E; Arteries; Atherosclerosis; Carotid Arteries; Cell Line; Chemistry, Pharmaceutical; Cholesterol; Chromatography, Liquid; Diagnostic Imaging; Disease Models, Animal; Drug Design; Glucose; Glucose-6-Phosphate; Humans; Hydrocarbons, Fluorinated; Ions; Liver X Receptors; Mass Spectrometry; Mice; Mice, Inbred C57BL; Mice, Knockout; Orphan Nuclear Receptors; Plaque, Atherosclerotic; Positron-Emission Tomography; Sulfonamides; Time Factors

Fenofibrate, a PPAR-α agonist and rosiglitazone, a PPAR-γ agonist, reduce triglycerides and fatty acids in humans and in animal disease models. The efficacy of PPAR-α agonists in mouse model of human atherosclerosis disease has shown mixed results, and efficacy of PPAR-γ and liver X receptor (LXR) agonists has not been evaluated in cholesterol ester transfer protein (CETP) producing animal models.. The efficacy of PPAR-α, PPAR-γ and LXR agonists on lipid lowering and antiatherosclerotic activities was studied in atherosclerosis-susceptible F(1)B hamster that showed greater responsiveness to dietary fat and cholesterol (HFHC) diet and increased severity of atherosclerosis compared to Golden Syrian (GS) hamsters (aortic lesion 0.3% in GS vs 5% in F(1)B). F(1)B hamsters were fed HFHC diet and simultaneously treated with fenofibrate, rosiglitazone, and T0901317 (a pan LXR agonist) for 8 weeks. Fenofibrate lowered triglycerides and LDL-C by >80%, rosiglitazone did not significantly impact plasma lipid levels, and as expected, T0901317 increased triglycerides by 3-fold and HDL-C by 50%. The lesions in the aortic arch area as measured by en face method, decreased by 81%, 38% and 35%, following fenofibrate, rosiglitazone, and T0901317 treatments, respectively. In F(1)B hamster regression model, fenofibrate decreased levels of triglycerides and LDL-C by >85%, and LDL-C by >70%, respectively, which resulted in ∼50% regression of aortic lesions compared to vehicle treated group, and ∼36% compared to baseline.. These results demonstrate that: (a) F(1)B hamster is more sensitive to developing diet-induced hyperlipidemia and atherosclerosis; and (b) the greater antiatherosclerotic efficacy of fenofibrate occurred primarily via reductions in proatherogenic lipoproteins. Thus, PPAR-α selective agonist shows a greater anti-atherosclerotic response compared to PPAR-γ and LXR agonists in diet-induced atherosclerosis-susceptible F(1)B hamster.

Topics: Animals; Anticholesteremic Agents; Atherosclerosis; Cholesterol; Cricetinae; Fatty Acids; Female; Fenofibrate; Hydrocarbons, Fluorinated; Hyperlipidemias; Liver X Receptors; Male; Mesocricetus; Orphan Nuclear Receptors; PPAR alpha; PPAR gamma; Rosiglitazone; Sulfonamides; Thiazolidinediones; Triglycerides

Liver X receptors (LXRs) are transcription factors involved in the regulation of cholesterol homeostasis. LXR ligands have athero-protective properties independent of their effects on cholesterol metabolism. Platelets are involved in the initiation of atherosclerosis and despite being anucleate express nuclear receptors. We hypothesized that the athero-protective effects of LXR ligands could be in part mediated through platelets and therefore explored the potential role of LXR in platelets. Our results show that LXR-β is present in human platelets and the LXR ligands, GW3965 and T0901317, modulated nongenomically platelet aggregation stimulated by a range of agonists. GW3965 caused LXR to associate with signaling components proximal to the collagen receptor, GPVI, suggesting a potential mechanism of LXR action in platelets that leads to diminished platelet responses. Activation of platelets at sites of atherosclerotic lesions results in thrombosis preceding myocardial infarction and stroke. Using an in vivo model of thrombosis in mice, we show that GW3965 has antithrombotic effects, reducing the size and the stability of thrombi. The athero-protective effects of GW3965, together with its novel antiplatelet/thrombotic effects, indicate LXR as a potential target for prevention of athero-thrombotic disease.

Topics: Animals; Atherosclerosis; Benzoates; Benzylamines; Calcium; Flow Cytometry; Humans; Hydrocarbons, Fluorinated; Immunoblotting; Immunoprecipitation; Ligands; Liver X Receptors; Mice; Mice, Inbred C57BL; Orphan Nuclear Receptors; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Platelet Membrane Glycoproteins; Sulfonamides; Thrombosis

Successful drug development has been hampered by a limited understanding of how to translate laboratory-based biological discoveries into safe and effective medicines. We have developed a generic method for predicting the effects of drugs on biological processes. Information derived from the chemical structure and experimental omics data from short-term efficacy studies are combined to predict the possible protein targets and cellular pathways affected by drugs.. Validation of the method with anti-atherosclerotic compounds (fenofibrate, rosuvastatin, LXR activator T0901317) demonstrated a great conformity between the computationally predicted effects and the wet-lab biochemical effects. Comparative genome-wide pathway mapping revealed that the biological drug effects were realized largely via different pathways and mechanisms. In line with the predictions, the drugs showed differential effects on inflammatory pathways (downstream of PDGF, VEGF, IFNγ, TGFβ, IL1β, TNFα, LPS), transcriptional regulators (NFκB, C/EBP, STAT3, AP-1) and enzymes (PKCδ, AKT, PLA2), and they quenched different aspects of the inflammatory signaling cascade. Fenofibrate, the compound predicted to be most efficacious in inhibiting early processes of atherosclerosis, had the strongest effect on early lesion development.. Our approach provides mechanistic rationales for the differential and common effects of drugs and may help to better understand the origins of drug actions and the design of combination therapies.

Topics: Animals; Anti-Inflammatory Agents; Atherosclerosis; Cardiovascular Agents; Drug Design; Fenofibrate; Fluorobenzenes; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Mice; Microarray Analysis; Models, Biological; Pyrimidines; Regulatory Elements, Transcriptional; Rosuvastatin Calcium; Structure-Activity Relationship; Sulfonamides; Systems Biology

The nuclear receptors Liver X receptors, LXRα and LXRβ, regulate cholesterol and triglyceride metabolism. We and others have previously reported that synthetic LXR agonists reduced atherosclerosis in models of mouse with no detectable plasma cholesteryl ester transfer protein (CETP) activity, which plays an important role in reverse cholesterol transport. In the present study, we investigated the effect of LXR activation in rabbits to elucidate the influence of CETP activity. First, we cloned rabbit LXRs cDNA. The data indicated that rabbit LXRα was mostly highly expressed in the liver, whereas LXRβ expression was ubiquitous. Next, we investigated the effect of LXR agonist on lipid levels. Treatment with LXR agonist T0901317 increased plasma CETP activity and consequently elevated LDL, but no change in HDL. High cholesterol (HC) diet-feeding, which is thought to provide oxysterols as the natural agonists, could also increase expression of CETP and other LXR target genes. Finally, we tested T0901317 in the atherosclerosis intervention study. Chronic administration of T0901317 significantly reduced atherosclerosis in HC diet-fed rabbits despite less favorable lipid profiles, i.e. increases of plasma triglycerides and no change of HDL. T0901317 induced ATP-binding cassette transporters ABCA1 and ABCG1 and suppressed inflammatory genes expression in the aorta, suggesting that direct actions of LXR agonist on vascular gene expression are likely to contribute to the antiatherogenic effect. The present work strongly supports the idea that LXR agonists could be beneficial as therapeutic agents for treatment of atherosclerosis.

Topics: Amino Acid Sequence; Animals; Anticholesteremic Agents; Aorta; Atherosclerosis; ATP-Binding Cassette Transporters; Cholesterol; Cholesterol Ester Transfer Proteins; Diet, High-Fat; Disease Models, Animal; Gene Expression; Hydrocarbons, Fluorinated; Lipoproteins, HDL; Lipoproteins, LDL; Liver; Liver X Receptors; Molecular Sequence Data; Orphan Nuclear Receptors; Rabbits; Recombinant Proteins; Signal Transduction; Sulfonamides; Triglycerides

A series of phenyl sulfone substituted quinoxaline were prepared and the lead compound 13 (WYE-672) was shown to be a tissue selective LXR Agonist. Compound 13 demonstrated partial agonism for LXRbeta in kidney HEK-293 cells but did not activate Gal4 LXRbeta fusion proteins in huh-7 liver cells. Although 13 showed potent binding affinity to LXRbeta (IC(50) = 53 nM), it had little binding affinity for LXRalpha (IC(50) > 1.0 microM) and did not recruit any coactivator/corepressor peptides in the LXRalpha multiplex assay. However, compound 13 showed good agonism in THP-1 cells with respect to increasing ABCA1 gene expression and good potency on cholesterol efflux in THP-1 foam cells. In an eight-week lesion study in LDLR -/- mice, compound 13 showed reduction of aortic arch lesion progression and no plasma or hepatic triglyceride increase. These results suggest quinoxaline 13 may have an improved biological profile for potential use as a therapeutic agent.

Topics: Animals; Area Under Curve; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; Cell Line; Cholesterol; Duodenum; Half-Life; Humans; Kidney; Liver; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Models, Molecular; Organ Specificity; Orphan Nuclear Receptors; Quinoxalines; Radioligand Assay; Structure-Activity Relationship; Sulfones; Transcriptional Activation; Triglycerides

A series of 4-(3-biaryl)quinolines with sulfone substituents on the terminal aryl ring (8) was prepared as potential LXR agonists. High affinity LXRbeta ligands with generally modest binding selectivity over LXRalpha and excellent agonist potency in LXR functional assays were identified. Many compounds had LXRbeta binding IC(50) values <10 nM while the most potent had EC(50) values <1.0 nM in an ABCA1 mRNA induction assay in J774 mouse cells with efficacy comparable to T0901317. Sulfone 8a was further evaluated in LDL (-/-) mice and shown to reduce atherosclerotic lesion progression.

Topics: Animals; Atherosclerosis; Binding Sites; Cell Line; Computer Simulation; Humans; Lipoproteins, LDL; Liver X Receptors; Mice; Mice, Knockout; Microsomes; Orphan Nuclear Receptors; Quinolines; Rats; Structure-Activity Relationship; Sulfones

Atherogenic lipids and chronic inflammation drive the development of cardiovascular disorders such as atherosclerosis. Many cardiovascular drugs target the liver which is involved in the formation of lipid and inflammatory risk factors. With robust systems biology tools and comprehensive bioinformatical packages becoming available and affordable, the effect of novel treatment strategies can be analyzed more comprehensively and with higher sensitivity. For example, beneficial as well as adverse effects of drugs can already be detected on the gene and metabolite level, and prior to their macroscopic manifestation. This chapter describes a systems approach for a prototype CV drug with established beneficial and adverse effects. All relevant steps, for example, experimental design, tissue collection and high quality RNA preparation, bioinformatical analysis of functional processes, and pathways (targeted and untargeted) are addressed.

Topics: Animals; Atherosclerosis; Cardiovascular Agents; Female; Gene Regulatory Networks; Humans; Hydrocarbons, Fluorinated; Inflammation; Liver X Receptors; Mice; Orphan Nuclear Receptors; RNA; Software; Statistics as Topic; Sulfonamides; Systems Biology

We have previously shown that mouse atherosclerosis regression involves monocyte-derived (CD68+) cell emigration from plaques and is dependent on the chemokine receptor CCR7. Concurrent with regression, mRNA levels of the gene encoding LXRalpha are increased in plaque CD68+ cells, suggestive of a functional relationship between LXR and CCR7. To extend these results, atherosclerotic Apoe-/- mice sufficient or deficient in CCR7 were treated with an LXR agonist, resulting in a CCR7-dependent decrease in plaque CD68+ cells. To test the requirement for LXR for CCR7-dependent regression, we transplanted aortic arches from atherosclerotic Apoe-/- mice, or from Apoe-/- mice with BM deficiency of LXRalpha or LXRbeta, into WT recipients. Plaques from both LXRalpha and LXRbeta-deficient Apoe-/- mice exhibited impaired regression. In addition, the CD68+ cells displayed reduced emigration and CCR7 expression. Using an immature DC line, we found that LXR agonist treatment increased Ccr7 mRNA levels. This increase was blunted when LXRalpha and LXRbeta levels were reduced by siRNAs. Moreover, LXR agonist treatment of primary human immature DCs resulted in functionally significant upregulation of CCR7. We conclude that LXR is required for maximal effects on plaque CD68+ cell expression of CCR7 and monocyte-derived cell egress during atherosclerosis regression in mice.

Topics: Animals; Antigens, CD; Antigens, Differentiation, Myelomonocytic; Aorta, Thoracic; Atherosclerosis; Cell Line; Cell Movement; Dendritic Cells; Female; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Liver X Receptors; Macrophages; Male; Mice; Mice, Mutant Strains; Orphan Nuclear Receptors; Plaque, Atherosclerotic; Receptors, CCR7; Sulfonamides

Liver X receptors (LXRs) promote macrophage reverse cholesterol transport and cholesterol excretion from the body. The synthetic LXR ligands T0901317 and GW3965 were shown to significantly inhibit atherosclerosis in mice and to increase the expression of ATP-binding cassette transporter A1 (ABCA1) in the atherosclerotic lesions. However, these compounds increase plasma and hepatic triglyceride (TG) levels in mice. Methyl-3β-hydroxy-5α,6α-epoxycholanate (MHEC), synthesized from hyodeoxycholic acid, functions as an LXR agonist, but its role in atherogenesis and lipid metabolism remained to be elucidated.. THP-1-derived macrophages were cultured in the medium con- taining various concentrations of MHEC or T0901317 (0-10 μmol/l) for 24 h. Reverse transcription polymerase chain reaction was used to quantify LXRα, LXRβ and ABCA1 mRNA levels in macrophages. Additionally, MHEC or T0901317 was orally administered at 10 mg/kg daily for 6 weeks in apolipoprotein E knockout (apoE⁻/⁻) mice fed a high-cholesterol diet. Plasma lipids were determined enzymatically. The area of and ABCA1 expression in the aortic atherosclerotic lesions were measured by oil red O staining and immunohistochemistry, respectively.. Both MHEC and T0901317 equally stimulated LXRα and ABCA1 mRNA expression in a dose-dependent manner in THP-1-derived macrophages, but they did not induce LXRβ mRNA expression significantly. The plasma levels of total cholesterol, TG and high-density lipoprotein cholesterol were significantly higher in T0901317-treated mice than in the vehicle-treated control group. Interestingly, MHEC treatment dramatically increased plasma high-density lipoprotein cholesterol without altering plasma levels of total cholesterol and TG. Both MHEC and T0901317 equally inhibited the development of atherosclerotic lesions in apoE⁻/⁻ mice. The expression of ABCA1, a cholesterol efflux transporter, was greatly induced by the two LXR agonists in the artery wall.. MHEC is a novel LXR agonist and it inhibits atherosclerosis in apoE⁻/⁻ mice without raising blood TG. Thus, MHEC relative to T0901317 may be a better therapeutic LXR agonist for the treatment of atherosclerosis.

Topics: Animals; Apolipoproteins E; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; Cells, Cultured; Chenodeoxycholic Acid; Dose-Response Relationship, Drug; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Liver X Receptors; Macrophages; Male; Mice; Mice, Knockout; Orphan Nuclear Receptors; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides; Triglycerides

Activation of liver X receptors (LXRs) has been reported to reduce atherosclerosis in mouse models. However, this can be associated with enhanced liver de novo lipogenesis and elevation of plasma triglyceride-rich VLDL, which may limit its clinical use. In this study, we administered orally the LXR agonist T0901317 to male LDLR-/- mice fed a Western diet. This induced a persistent enhanced hypertriglyceridemia by largely increasing plasma triglyceride-rich VLDL. T0901317 treatment decreased atherosclerosis with a much more pronounced response and dose dependence in the innominate artery than in the aortic sinus. Lesions in the innominate artery were less complex containing mostly macrophage foam cells in T0901317-treated mice. However, in the aortic root, a significant reduction of atherosclerosis was seen only in the right coronary-related aortic sinus (RC) of T0901317-treated mice. Increasing the dose of T0901317 did not extend atheroprotection to the other sinuses of the aortic root. Lesions in the RC were less complex both in T0901317 and vehicle-treated mice with macrophage foam cells predominating. On the other hand, in T0901317-treated mice, the left coronary-related sinus (LC) lesions while not reduced in size, were more complex with a large fibrous cap and necrotic core, more collagen-positive areas, and variable macrophage foam cell content compared to vehicle-treated mice. These data suggest that activation of LXR by T0901317 had differential anti-atherosclerotic effects in two arterial regions in mice with hypertriglyceridemia.

Topics: Animals; Atherosclerosis; Brachiocephalic Trunk; DNA-Binding Proteins; Foam Cells; Gene Expression Regulation; Hydrocarbons, Fluorinated; Hypertriglyceridemia; Lipids; Liver X Receptors; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Orphan Nuclear Receptors; Receptors, Cytoplasmic and Nuclear; Sinus of Valsalva; Sulfonamides

The aim of this study was to define the anti-atherosclerotic role of liver-X-receptors (LXRs) under lesion progressive and lesion regressive conditions, to establish a temporal line of events, and to gain insights into the mechanisms underlying the anti-atherogenic potency of LXRs. We used apoE*3Leiden (E3L) mice to comprehensively and time-dependently dissect how T0901317, an LXR-agonist, inhibits initiation and progression of atherosclerotic lesions and regresses existing lipid- and macrophage-rich lesions. T0901317 suppresses lesion evolution and promotes lesion regression regarding lesion number, area, and severity. Quantitative plasma and vessel wall analyses corroborated by immunohistochemical evaluation of the aortic lesions revealed that under progressive (high-cholesterol diet) as well as regressive (cholesterol-free diet) conditions T0901317: i) significantly increases plasma triglyceride and total cholesterol levels; ii) does not affect the systemic inflammation marker, Serum amyloid A (SAA); iii) suppresses endothelial monocyte adhesion; and iv) induces the expression of the cholesterol efflux-related genes apolipoprotein E (apoE), ATP binding cassette (ABC) transporters ABCA1 and ABCG1. Furthermore, under progressive conditions, T0901317 suppresses the vascular inflammatory status (NF-kappaB) and the vascular expression of adhesion molecules [E-selectin, intercellular adhesion molecule (ICAM)-1, and CD44], lowers lesional macrophage accumulation, and blocks lesion evolution at the transition from lesional stage II to III. Under regressive conditions, T0901317 induces lesional macrophage disappearance and increases the expression of the chemokine receptor CCR7, a factor functionally required for regression. The LXR-agonist T0901317 retards vascular lesion development and promotes lesion regression at several levels. The findings support that vascular LXR is a potential anti-atherosclerotic target.

Topics: Animals; Anticholesteremic Agents; Apolipoprotein E3; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; DNA-Binding Proteins; E-Selectin; Female; Hyaluronan Receptors; Hydrocarbons, Fluorinated; Intercellular Adhesion Molecule-1; Lipoproteins; Liver X Receptors; Mice; Mice, Transgenic; Orphan Nuclear Receptors; Receptors, Cytoplasmic and Nuclear; Serum Amyloid A Protein; Sulfonamides

Vascular smooth muscular cells (VSMC) express lipogenic genes. Therefore in situ lipogenesis could provide fatty acids for triglycerides synthesis and cholesterol esterification and contribute to lipid accumulation in arterial wall with aging and during atheroma.. We investigated expression of lipogenic genes in human and rat arterial walls, its regulation in cultured VSMC and determined if it is modified during insulin-resistance and diabetes, situations with increased risk for atheroma.. Zucker obese (ZO) and diabetic (ZDF) rats accumulated more triglycerides in their aortas than their respective control rats, and this triglycerides content increased with age in ZDF and control rats. However the expression in aortas of lipogenic genes, or of genes involved in fatty acids uptake, was not higher in ZDF and ZO rats and did not increase with age. Expression of lipogenesis-related genes was not increased in human arterial wall (carotid endarterectomy) of diabetic compared to non-diabetic patients. In vitro, glucose and adipogenic medium (ADM) stimulated moderately the expression and activity of lipogenesis in VSMC from control rats. LXR agonists, but not PXR agonist, stimulated also lipogenesis in VSMC but not in arterial wall in vivo. Lipogenic genes expression was lower in VSMC from ZO rats and not stimulated by glucose or ADM.. Lipogenic genes are expressed in arterial wall and VSMC; this expression is stimulated (VSMC) by glucose, ADM and LXR agonists. During insulin-resistance and diabetes, this expression is not increased and resists to the actions of glucose and ADM. It is unlikely that this metabolic pathway contribute to lipid accumulation of arterial wall during insulin-resistance and diabetes and thus to the increased risk of atheroma observed in these situations.

Topics: Aged; Animals; Aorta; Atherosclerosis; Carotid Arteries; Cells, Cultured; Culture Media; Diabetes Mellitus, Type 2; Disease Models, Animal; Female; Gene Expression Regulation; Glucose; Humans; Hydrocarbons, Fluorinated; Insulin; Insulin Resistance; Lipogenesis; Liver X Receptors; Male; Middle Aged; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Obesity; Orphan Nuclear Receptors; Rats; Rats, Zucker; RNA, Messenger; Sulfonamides; Time Factors; Triglycerides

In this study, we studied the effect of liver X receptor (LXR) agonist T0901317 on Niemann-Pick C1 protein (NPC1) expression in apoE-/- mice. Male apoE-/- mice were randomized into 4 groups, baseline group (n=10), control group (n = 14), treatment group (n = 14) and prevention group (n = 14). All of the mice were fed with a high-fat/high-cholesterol (HFHC) diet containing 15% fat and 0.25% cholesterol. The baseline group treated with vehicle was sacrificed after 8 weeks of the diet. The control group and the prevention group were treated with either vehicle or T0901317 daily by oral gavage for 14 weeks. The treatment group was treated with vehicle for 8 weeks, and then was treated with the agonist T0901317 for additional 6 weeks. Gene and protein expression was analyzed by real-time quantitative PCR, immunohistochemistry and Western blotting, respectively. Plasma lipid concentrations were measured by commercially enzymatic methods. We used RNA interference technology to silence NPC1 gene expression in THP-1 macrophage-derived foam cells and then detected the effect of LXR agonist T0901317 on cholesterol efflux. Plasma triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and apoA-I concentrations were markedly increased in T0901317-treated groups. T0901317 treatment reduced the aortic atherosclerotic lesion area by 64.2% in the prevention group and 58.3% in the treatment group. LXR agonist treatment increased NPC1 mRNA expression and protein levels in the small intestine, liver and aorta of apoE-/- mice. Compared with the normal cells, cholesterol efflux of siRNA THP-1 macrophage-derived foam cells was significantly decreased, whereas cholesterol efflux of LXR agonist T0901317-treated THP-1 macrophage-derived foam cells was significantly increased. Our results suggest that LXR agonist T0901317 inhibits atherosclerosis development in apoE-/- mice, which is related to up-regulating NPC1 expression.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; Base Sequence; Cell Line; DNA Primers; DNA-Binding Proteins; Hydrocarbons, Fluorinated; Immunohistochemistry; Intestinal Mucosa; Intracellular Signaling Peptides and Proteins; Liver; Liver X Receptors; Male; Mice; Mice, Knockout; Niemann-Pick C1 Protein; Orphan Nuclear Receptors; Proteins; Receptors, Cytoplasmic and Nuclear; Sulfonamides; Up-Regulation

Liver X receptors (LXRs) are oxysterol-activated nuclear receptors regulating reverse cholesterol transport, in part by modulating cholesterol efflux from macrophages to apoAI and HDL via the ABCA1 and ABCG1/ABCG4 pathways. Moreover, LXR activation increases intracellular cholesterol trafficking via the induction of NPC1 and NPC2 expression. However, implication of LXRs in the selective uptake of cholesteryl esters from lipoproteins in human macrophages has never been reported.. Our results show that (1) selective CE uptake from HDL(3) is highly efficient in human monocyte-derived macrophages; (2) surprisingly, HDL(3)-CE uptake is strongly increased by LXR activation despite antiatherogenic effects of LXRs; (3) HDL(3)-CE uptake increase is not linked to SR-BI expression modulation but it is dependent of proteoglycan interactions; (4) HDL(3)-CE uptake increase is associated with increased expression and secretion of apoE and LPL, two proteins interacting with proteoglycans; (5) HDL(3)-CE uptake increase depends on the integrity of raft domains and is associated with an increased caveolin-1 expression.. Our study identifies a new role for LXRs in the control of cholesterol homeostasis in human macrophages. LXR activation results in enhanced dynamic intracellular cholesterol fluxes through an increased CE uptake from HDL and leads to an increased cholesterol availability to efflux to apoAI and HDL.

Topics: Apolipoprotein A-I; Atherosclerosis; Biological Transport, Active; Caveolin 1; Cells, Cultured; Cholesterol Esters; Cholesterol, HDL; DNA-Binding Proteins; Humans; Hydrocarbons, Fluorinated; Lipoproteins, HDL; Liver X Receptors; Macrophages; Membrane Microdomains; Orphan Nuclear Receptors; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Scavenger Receptors, Class B; Sulfonamides

Semicarbazide-sensitive amine oxidase (SSAO) catalyzes oxidative deamination of primary aromatic and aliphatic amines. Increased SSAO activity has been found in atherosclerosis and diabetes mellitus. We hypothesize that the anti-atherogenic effect of liver X receptors (LXRs) might be related to the inhibition of SSAO gene expression and its activity. In this study, we investigated the effect of LXR agonist T0901317 on SSAO gene expression and its activity in apolipoprotein E knockout (apoE(-/-)) mice. Male apoE(-/-) mice (8 weeks old) were randomly divided into four groups: basal control group; vehicle group; prevention group; and treatment group. SSAO gene expression was analyzed by real-time quantitative polymerase chain reaction and its activity was determined. The activity of superoxide dismutase and content of malondialdehyde in the aorta and liver were also determined. In T0901317-treated mice, SSAO gene expression was significantly decreased in the aorta, liver, small intestine, and brain. SSAO activities in serum and in these tissues were also inhibited. The amount of superoxide dismutase in the aorta and liver of the prevention group and treatment group was significantly higher compared with the vehicle group (P<0.05). Malondialdehyde in the tissues of these two groups was significantly lower compared with the vehicle group (P<0.05). Our results showed that T0901317 inhibits SSAO gene expression and its activity in atherogenic apoE(-/-) mice. The atheroprotective effect of LXR agonist T0901317 is related to the inhibition of SSAO gene expression and its activity.

Topics: Amine Oxidase (Copper-Containing); Animals; Apolipoproteins E; Atherosclerosis; Cell Adhesion Molecules; DNA-Binding Proteins; Enzyme Activation; Gene Expression Regulation, Enzymologic; Hydrocarbons, Fluorinated; Liver X Receptors; Male; Mice; Mice, Knockout; Orphan Nuclear Receptors; Receptors, Cytoplasmic and Nuclear; Sulfonamides

Although a range of studies indicated Liver X receptor (LXR) activation inhibited the development of atherosclerosis in animal models, the mechanism of this effect for LXR agonists has not been fully understood. A recent study has suggested LXR activators increased the amount of free cholesterol in the plasma membrane of human macrophages by inducing Niemann-Pick type C1 (NPC1) gene expression. Therefore, we hypothesize that LXRs may also promote NPC1 expression in vivo. Here we investigated the effect of a synthetic LXR agonist T0901317 on ATP-binding cassette transporter A1 (ABCA1) and NPC1 in apolipoprotein E knockout (apoE-/-) mice. Male apoE-/- mice were randomized into four groups: baseline group (n = 10), vehicle group (n = 14), prevention group (n = 14), and treatment group (n = 14). En face analysis and Oil red O staining were used to examine the aortic atherosclerotic lesions. Macrophage content of aortic root atherosclerotic lesions and cholesterol efflux form peritoneal macrophages were measured. Gene and protein expression was analyzed by real-time quantitative polymerase chain reaction and Western blotting, respectively. T0901317 treatment reduced aortic atherosclerotic lesion area by 64.2% in prevention group (P < 0.001) and 58.3% in treatment group (P < 0.001) and resulted in a reduction in macrophage content. Plasma triglyceride, total cholesterol, high-density lipoprotein cholesterol, and apoA-I concentrations were markedly increased in T0901317-treated groups. T0901317 also promoted ABCA1 and NPC1 gene and protein levels in the aorta, liver, and small intestine of apoE-/- mice and significantly increased cholesterol efflux from peritoneal macrophages. T0901317 upregulates ABCA1 and NPC1. This study gives us a new insight into the mechanism for antiatherogenic effect of LXR synthetic agonists.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; Blotting, Western; Cells, Cultured; Cholesterol; DNA-Binding Proteins; Hydrocarbons, Fluorinated; Intestine, Small; Intracellular Signaling Peptides and Proteins; Liver; Liver X Receptors; Macrophages; Macrophages, Peritoneal; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Niemann-Pick C1 Protein; Orphan Nuclear Receptors; Polymerase Chain Reaction; Proteins; Receptors, Cytoplasmic and Nuclear; Sulfonamides

Atherosclerosis is considered to be a combined disorder of lipid metabolism and chronic inflammation. Recent studies have reported that liver X receptors (LXRs) are involved in lipid metabolism and inflammation and that LXR agonists inhibit atherogenesis. In contrast, angiotensin II is well known to accelerate atherogenesis through activation of the angiotensin II type 1 receptor (AT1R). To better understand the mechanism of LXR on the prevention of atherogenesis, we examined whether activation of LXR affects AT1R expression in vascular smooth muscle cells. T0901317, a synthetic LXR ligand, decreased AT1R mRNA and protein expression with a peak reduction at 6 hours and 12 hours of incubation, respectively. A well-established ligand of LXR, 22-(R)-hydroxycholesterol, also suppressed AT1R expression. The downregulation of AT1R by T0901317 required de novo protein synthesis. AT1R gene promoter activity measured by luciferase assay revealed that the DNA segment between -61 bp and +25 bp was sufficient for downregulation. Luciferase construct with a mutation in Sp1 binding site located in this segment lost its response to T0901317. T0901317 decreased Sp1 serine phosphorylation. Although preincubation of vascular smooth muscle cells with T0901317 for 30 minutes had no effect on angiotensin II-induced extracellular signal-regulated kinase phosphorylation, phosphorylation of extracellular signal-regulated kinase by angiotensin II was markedly suppressed after 6 hours of preincubation. These results indicate that the suppression of AT1R may be one of the important mechanisms by which LXR ligands exert antiatherogenic effects.

Topics: Angiotensin II; Animals; Aorta, Thoracic; Atherosclerosis; Cells, Cultured; Cyclin-Dependent Kinase Inhibitor p16; DNA-Binding Proteins; Down-Regulation; Gene Expression Regulation; Histone Deacetylases; Hydrocarbons, Fluorinated; Liver X Receptors; Muscle, Smooth, Vascular; Mutagenesis; Orphan Nuclear Receptors; Phosphorylation; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Receptor, Angiotensin, Type 1; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Sp1 Transcription Factor; Sulfonamides; Transcription, Genetic; Vasoconstrictor Agents

Patients with type 2 diabetes mellitus are at increased risk for the development of atherosclerosis. A pivotal event in the development of atherosclerosis is macrophage foam cell formation. The ATP-binding cassette (ABC) transporters ABCA1 and ABCG1 regulate macrophage cholesterol efflux and hence play a vital role in macrophage foam cell formation. We have previously found that chronic elevated glucose reduces ABCG1 expression. In the present study, we examined whether patients with type 2 diabetes mellitus had decreased ABCG1 and/or ABCA1, impaired cholesterol efflux, and increased macrophage foam cell formation.. Blood was collected from patients with and without type 2 diabetes mellitus. Peripheral blood monocytes were differentiated into macrophages, and cholesterol efflux assays, immunoblots, histological analysis, and intracellular cholesteryl ester measurements were performed. Macrophages from patients with type 2 diabetes mellitus had a 30% reduction in cholesterol efflux with a corresponding 60% increase in cholesterol accumulation relative to control subjects. ABCG1 was present in macrophages from control subjects but was undetectable in macrophages from patients with type 2 diabetes mellitus. In contrast, ABCA1 expression in macrophages was similar in both control subjects and patients with type 2 diabetes mellitus. Macrophage expression of ABCG1 in both patients and control subjects was induced by treatment with the liver X receptor agonist TO-901317. Upregulation of liver X receptor dramatically reduced foam cell formation in macrophages from patients with type 2 diabetes mellitus.. ABCG1 expression and cholesterol efflux are reduced in patients with type 2 diabetes mellitus. This impaired ABCG1-mediated cholesterol efflux significantly correlates with increased intracellular cholesterol accumulation. Strategies to upregulate ABCG1 expression and function in type 2 diabetes mellitus could have therapeutic potential for limiting the accelerated vascular disease observed in patients with type 2 diabetes mellitus.

Topics: Atherosclerosis; ATP Binding Cassette Transporter, Subfamily G, Member 1; ATP-Binding Cassette Transporters; Cell Differentiation; Cells, Cultured; Cholesterol Esters; Cholesterol, HDL; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Female; Gene Expression; Humans; Hydrocarbons, Fluorinated; Macrophages; Male; Middle Aged; Monocytes; Sulfonamides

In present study, we employed cDNA-based microarray technique to investigate the effect of a synthetic LXR ligand T0901317 on hepatic gene expression of proinflammatory cytokines in apolipoprotein E knockout mice fed an atherogenic diet.. Male 8-week-old apoE-/- mice were randomly divided into four groups, baseline group, vehicle group, prevention group and treatment group. All of the mice were fed a high-fat/high-cholesterol diet with or without LXR agonist T0901317 for 8 or 14 weeks. Gene array analysis found 17 atherosclerosis-related genes with a 2- to 8-fold difference in expression level between vehicle-treated group and T0901317-treated group. It induced mRNA expression of proinflammatory cytokine tumor necrosis factor (TNF), but inhibited gene expression of several other proinflammatory cytokines including interleukin (IL)-1alpha, IL-6, and IL-7 in the liver. C-reactive protein, TNF, matrix metalloproteinase-9, IL-1alpha, IL-6, and IL-7 were verified by real-time quantitative PCR. Next, enzyme-linked immunosorbent assay analyses showed up-regulation of TNFalpha levels and down-regulation of IL-alpha, IL-6, IL-7 levels in plasma sample.. The synthetic LXR agonist T0901317 has paradoxical roles in hepatic gene expression of proinflammatory cytokines in apoE-/- mice.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; C-Reactive Protein; Cholesterol, Dietary; DNA-Binding Proteins; Gene Expression; Gene Expression Profiling; Hydrocarbons, Fluorinated; Interleukin-1alpha; Interleukin-6; Interleukin-7; Liver; Liver X Receptors; Male; Matrix Metalloproteinase 9; Mice; Mice, Mutant Strains; Oligonucleotide Array Sequence Analysis; Orphan Nuclear Receptors; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; Sulfonamides; Tumor Necrosis Factor-alpha

A series of branched and unbranched anilinohexafluoroisopropanols related to the known sulfonamide T0901317 were prepared and evaluated as activators/modulators of both LXRalpha and LXRbeta. A structure-activity relationship was established and compounds with high potency on both the receptors were identified. Many compounds showed a tendency toward selectivity for LXRbeta versus LXRalpha. Several analogues were evaluated for effects on plasma lipoprotein levels in mice. A few of these significantly raised HDL-cholesterol levels in plasma but showed markedly different effects on liver triglyceride content, suggesting that this series may yield candidates with improved efficacy/safety profiles compared to existing molecules.

Topics: Aniline Compounds; Animals; Atherosclerosis; Cholesterol, HDL; DNA-Binding Proteins; Lipoproteins; Liver; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Orphan Nuclear Receptors; Propanols; Receptors, Cytoplasmic and Nuclear; Structure-Activity Relationship; Transcriptional Activation; Triglycerides

A structure-based approach was used to optimize our new class of quinoline LXR modulators leading to phenyl acetic acid substituted quinolines 15 and 16. Both compounds displayed good binding affinity for LXRbeta and LXRalpha and were potent activators in LBD transactivation assays. The compounds also increased expression of ABCA1 and stimulated cholesterol efflux in THP-1 cells. Quinoline 16 showed good oral bioavailability and in vivo efficacy in a LDLr knockout mouse model for lesions.

Topics: Animals; Anticholesteremic Agents; Atherosclerosis; ATP Binding Cassette Transporter 1; ATP-Binding Cassette Transporters; Binding Sites; Biological Availability; Cell Line; Cholesterol; DNA-Binding Proteins; Drug Stability; Female; Humans; In Vitro Techniques; Ligands; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Microsomes, Liver; Models, Molecular; Molecular Structure; Orphan Nuclear Receptors; Phenylacetates; Protein Structure, Tertiary; Quinolines; Receptors, Cytoplasmic and Nuclear; Structure-Activity Relationship; Transcriptional Activation

CD4-positive lymphocytes, the major T-cell population in human atheroma, mainly secrete Th-1-type proinflammatory cytokines, like interferon (IFN)gamma, tumor necrosis factor (TNF)alpha, and interleukin (IL)-2, thus promoting atherogenesis. Recent data suggest that the nuclear transcription factors liver X receptor-alpha and liver X receptor-beta (LXRalpha and LXRbeta) limit plaque formation in animal models by modulating macrophage function. Still, the role of LXRs in CD4-positive lymphocytes is currently unexplored.. Human CD4-positive lymphocytes express LXRalpha and LXRbeta mRNA and protein. Activation of CD4-positive cells by anti-CD3 mAbs, anti-CD3/CD28 mAbs, as well as PMA/ionomycin significantly increased Th1-cytokine mRNA and protein expression. Treatment with the LXR activator T0901317 reduced this increase of IFNgamma, TNFalpha, and IL-2 in a concentration-dependent manner with a maximum at 1 micromol/L T0901317. Transient transfection assays revealed an inhibition of IFNgamma promoter activity by T0901317 as the underlying molecular mechanism. Such anti-inflammatory actions were also evident in cell-cell interactions with medium conditioned by T0901317-treated CD4-positive cells attenuating human monocyte CD64 expression.. Human CD4-positive lymphocytes express both LXRalpha and LXRbeta, and LXR activation can reduce Th-1 cytokine expression in these cells. These data provide new insight how LXR activators might modulate the inflammatory process in atherogenesis and as such influence lesion development.

Topics: Atherosclerosis; CD28 Antigens; CD3 Complex; CD4-Positive T-Lymphocytes; Cells, Cultured; Cytokines; DNA-Binding Proteins; Humans; Hydrocarbons, Fluorinated; Interferon-gamma; Liver X Receptors; Monocytes; Orphan Nuclear Receptors; Promoter Regions, Genetic; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Sulfonamides; Th1 Cells; Th2 Cells

Myeloperoxidase (MPO) is an oxidant-generating enzyme expressed in macrophages and implicated in atherosclerosis and cholesterol homeostasis. LXRalpha and PPARalpha regulate genes involved in cholesterol metabolism and the inflammatory response in macrophages. Here, we examine the effect of LXR and PPARalpha ligands on MPO expression. LXR and PPARalpha, as heterodimers with RXR, are shown to bind overlapping sites in an Alu receptor response element (AluRRE) in the MPO promoter. The LXR ligand T0901317 suppresses MPO mRNA expression in primary human macrophages, and in bone marrow cells and macrophages from huMPO transgenic mice. The PPARalpha ligand GW9578 downregulates MPO expression in GMCSF-macrophages, while upregulating in MCSF-macrophages. In contrast, the mouse MPO gene, which lacks the primate-specific AluRRE, is not regulated by LXR or PPARalpha ligands. These findings identify human MPO as a novel LXR and PPARalpha target gene, consistent with the role of these receptors in regulation of proinflammatory genes in macrophages.

Topics: Animals; Atherosclerosis; Bone Marrow Cells; Cell Nucleus; DNA-Binding Proteins; Gene Expression Regulation; Humans; Hydrocarbons, Fluorinated; Leukocytes, Mononuclear; Liver X Receptors; Macrophages; Mice; Mice, Inbred C57BL; Orphan Nuclear Receptors; Peroxidase; PPAR alpha; Receptors, Cytoplasmic and Nuclear; Sulfonamides