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Background: Accumulation of excess cholesterol by intimal arterial smooth muscle cells (SMCs) contributes to the formation of foam cells in atherosclerotic lesions. The purpose of this study was to examine the expression and activity of ATP-binding cassette transporter A1 (ABCA1) in model intimal and medial arterial SMCs, in human atherosclerotic coronary artery intimal and medial layers, and in human intimal and medial SMCs., Methods and Results: Model intimal arterial SMCs showed increased cholesteryl ester accumulation, absence of apolipoprotein A-I-mediated lipid efflux, markedly diminished ABCA1 expression, and poor apoA-I binding compared with medial-layer SMCs. Total ABCA1 mRNA and SMC-specific ABCA1 protein levels were diminished in the intimal layer compared with the medial layer of atherosclerotic human coronary arteries. Increased expression of ABCA1 by liver X receptor agonist treatment or gene transfection failed to correct apolipoprotein A-I binding, lipid efflux, or high-density lipoprotein particle formation by intima-type SMCs. In addition to impaired ABCA1 expression, intima-type SMCs appear to lack a critical binding factor or factors required for the apolipoprotein A-I-ABCA1 interaction, cholesterol efflux, and high-density lipoprotein particle formation., Conclusions: ABCA1 expression is reduced in cultured model intimal and human atherosclerotic lesion SMCs, suggesting that reduced ABCA1 activity contributes to smooth muscle foam cell formation in the intima.

Objective: The aim of this study is to estimate the willingness of multiple sclerosis (MS) patients to accept life-threatening adverse event risks in exchange for improvements in their MS related health outcomes., Methods: MS patients completed a survey questionnaire that included a series of choice-format conjoint tradeoff tasks. Patients chose hypothetical treatments from pairs of treatment alternatives with varying levels of clinical efficacy and associated risks., Results: Among the 651 patients who completed the survey, delay in years to disability progression was the most important factor in treatment preferences. In return for decreases in relapse rates from 4 to 1 and increases in delay in progression from 3 to 5 years, patients were willing to accept a 0.38% annual risk of death or disability from PML, a 0.39% annual risk of death from liver failure or a 0.48% annual risk of death from leukemia., Conclusions: Medical interventions carry risks of adverse outcomes that must be evaluated against their clinical benefits. Most MS patients indicated they are willing to accept risks in exchange for clinical efficacy. Patient preferences for potential benefits and risks can assist in decision-making.

Phosphatidylethanolamine N-methyltransferase (PEMT) is a liver-specific enzyme that converts phosphatidylethanolamine to phosphatidylcholine (PC). Mice that lack PEMT have reduced plasma levels of PC and cholesterol in high density lipoproteins (HDL). We have investigated the mechanism responsible for this reduction with experiments designed to distinguish between a decreased formation of HDL particles by hepatocytes or an increased hepatic uptake of HDL lipids. Therefore, we analyzed lipid efflux to apoA-I and HDL lipid uptake using primary cultured hepatocytes isolated from Pemt(+/+) and Pemt(-/-) mice. Hepatic levels of the ATP-binding cassette transporter A1 are not significantly different between Pemt genotypes. Moreover, hepatocytes isolated from Pemt(-/-) mice released cholesterol and PC into the medium as efficiently as did hepatocytes from Pemt(+/+) mice. Immunoblotting of liver homogenates showed a 1.5-fold increase in the amount of the scavenger receptor, class B, type 1 (SR-BI) in Pemt(-/-) compared with Pemt(+/+) livers. In addition, there was a 1.5-fold increase in the SR-BI-interacting protein PDZK1. Lipid uptake experiments using radiolabeled HDL particles revealed a greater uptake of [(3)H]cholesteryl ethers and [(3)H]PC by hepatocytes derived from Pemt(-/-) compared with Pemt(+/+) mice. Furthermore, we observed an increased association of [(3)H]cholesteryl ethers in livers of Pemt(-/-) compared with Pemt(+/+) mice after tail vein injection of [(3)H]HDL. These results strongly suggest that PEMT is involved in the regulation of plasma HDL levels in mice, mainly via HDL lipid uptake by SR-BI.

Purpose of Review: The removal of cellular cholesterol and phospholipids to apolipoprotein A-I (apoA-I), facilitated by the membrane transporter ATP-binding cassette transporter A1 (ABCA1), is the rate-limiting step in the formation of high density lipoprotein particles. This review summarizes recent literature concerning the relative contributions of different cellular pools of cholesterol used by ABCA1 in the initial lipidation of apoA-I for high density lipoprotein particle formation., Recent Findings: Cell culture studies have shown that apart from lipidating apoA-I directly, ABCA1 can also mediate cholesterol delivery indirectly to apoA-I in the plasma membrane. Moreover, it is now clear that the late endosome/lysosome pool of cholesterol is a critical part of the total cholesterol substrate pool for ABCA1. Internalization of ABCA1 appears to be a requirement for maximum ABCA1-mediated cholesterol mobilization for high density lipoprotein formation., Summary: Current evidence suggests that ABCA1-mediated cholesterol efflux to apoA-I involves mobilization of cholesterol from plasma membrane, endoplasmic reticulum, trans-Golgi network, late endocytic and lysosomal compartments, and cholesteryl ester droplets. Apart from lipidating apoA-I directly, ABCA1 has also been found to efflux cholesterol indirectly to apoA-I in plasma membranes.

The Niemann-Pick C1 (NPC1) protein regulates the transport of cholesterol from late endosomes/lysosomes to other compartments responsible for maintaining intracellular cholesterol homeostasis. The present study examined the expression of the NPC1 gene and the distribution of the NPC1 protein that resulted from the transport of LDL-derived cholesterol through normal human fibroblasts. A key finding was that the transport of cholesterol from late endosomes/lysosomes to the sterol-regulatory pool at the endoplasmic reticulum, as determined by feedback inhibition of the sterol-regulatory element binding protein (SREBP) pathway, was associated with the downregulation of the NPC1 gene. Consistent with these results, fibroblasts incubated with LDL had decreased amounts of SREBP protein that interacted with sterol-regulatory element (SRE) sequences positioned within the NPC1 gene promoter region. Finally, partial colocalization of the NPC1 protein with late endosomes/lysosomes and distinct regions of the endoplasmic reticulum suggested that the NPC1 protein may facilitate the transport of cholesterol directly between these two compartments. Together, these results indicate that the transport of LDL-derived cholesterol from late endosomes/lysosomes to the sterol-regulatory pool, known to be regulated by the NPC1 protein, is responsible for promoting feedback inhibition of the SREBP pathway and downregulation of the NPC1 gene.

CTP:phosphocholine cytidylyltransferase (CT) is the key regulatory enzyme in the CDP-choline pathway for the biosynthesis of phosphatidylcholine (PC). We previously generated a mouse in which the hepatic CTalpha gene was specifically inactivated by the cre/loxP procedure. In CTalpha knock-out mice, plasma high density lipoprotein (HDL) and very low density lipoprotein (VLDL) levels were markedly lower than in wild type mice (Jacobs, R. L., Devlin, C., Tabas, I., and Vance, D. E. (2004) J. Biol. Chem. 279, 47402-47410.) To investigate the mechanism(s) responsible for the decrease in plasma lipoprotein levels, we isolated primary hepatocytes from knock-out and wild type mice. ABCA1 expression was reduced in knock-out hepatocytes and apoAI-dependent cholesterol, and PC efflux was impaired. When knock-out hepatocytes were infected with an adenovirus expressing CTalpha, apoAI-dependent PC efflux returned partially, whereas cholesterol efflux and ABCA1 levels were not restored to normal levels. Adenoviral expression of CTalpha did not increase VLDL secretion in knock-out hepatocytes, even though cellular PC levels returned to normal. However, in vivo adenoviral delivery of CTalpha normalized plasma HDL and VLDL levels in knock-out mice. The observations demonstrate that hepatic PC biosynthesis is a key player in maintaining plasma VLDL and HDL, and further underscores the importance of the liver in HDL formation.

Background: Specialty cardiovascular risk reduction clinics (CRRC) increase the proportion of patients attaining recommended lipid targets; however, it is not known if the benefits are sustained after discharge. We evaluated the impact of a CRRC on lipid levels and assessed the long-term effect of a CRRC in maintaining improved lipid levels following discharge., Methods: The medical records of consecutive dyslipidemic patients discharged > 6 months from a tertiary hospital CRRC from January 1991 to January 2001 were retrospectively reviewed. The primary outcome was the change in patients' lipid levels between the final CRRC visit and the most recent primary care follow-up. A worst-case analysis was conducted to evaluate the potential impact of the patients in whom the follow-up lipid profiles post-discharge from the CRRC were not obtained., Results: Within the CRRC (median follow-up = 1.28 years in 1064 patients), we observed statistically significant improvements in all lipid parameters. In the 411 patients for whom post-discharge lipid profiles were available (median follow-up = 2.41 years), there were no significant differences observed in low-density lipoprotein-cholesterol, total cholesterol (TC), or triglycerides since CRRC discharge; however, there were small improvements in high-density lipoprotein-cholesterol (HDL-C) and TC:HDL ratio (p < 0.05 for both). The unadjusted worst-case analysis (653 patients with no follow-up lipid profiles) demonstrated statistically significant worsening of all lipid parameters between CRRC discharge and the most recent follow-up. However, when the change in lipid parameters between the baseline and the most recent follow-up was assessed in this analysis, the changes in all lipid parameters were significantly improved (p < 0.05)., Conclusions: This study demonstrates that a CRRC can improve lipid levels and suggests that these benefits are sustained once patients are returned to the care of their primary physician.

Niemann-Pick type C1 (NPC1) disease is an autosomal recessive disorder characterized clinically by neonatal jaundice, hepatosplenomegaly, vertical gaze palsy, ataxia, dystonia, and progressive neurodegeneration. The present study provides basic clinical and health information from the National Niemann-Pick C1 disease database that was obtained using a clinical questionnaire of 83 questions mailed to families affected by NPC1 disease living in the United States. The study was conducted over a 1-year period, during which time parents/caregivers and physicians completed the clinical questionnaire. Sixty-four percent (87/136) of the questionnaires were returned, with 53% and 47% representing male and female NPC1 patients, respectively. The average age of diagnosis for NPC1 disease was 10.4 years, with one-half of patients being diagnosed before the age of 6.9 years. The average age of death for NPC1 disease was 16.2 years, with one-half of patients dying before the age of 12.5 years. A common clinical symptom reported at birth was neonatal jaundice (52%), followed by enlargement of the spleen (36%) and liver (31%); ascites (19%) and neonatal hypotonia (6%) were much less frequent. With respect to developmental difficulties, the most common findings included clumsiness (87%), learning difficulties (87%), ataxia (83%), dysphagia (80%), and vertical gaze palsy (81%). Together, these findings confirm and extend previous reports investigating the clinical features associated with NPC1 disease., (Copyright (c) 2007 Wiley-Liss, Inc.)

Impaired cell cholesterol trafficking in Niemann-Pick type C (NPC) disease results in the first known instance of impaired regulation of the ATP-binding cassette transporter A1 (ABCA1), a lipid transporter mediating the rate-limiting step in high density lipoprotein (HDL) formation, as a cause of low plasma HDL-cholesterol in humans. We show here that treatment of human NPC1(-/-) fibroblasts with the liver X receptor (LXR) agonist TO-901317 increases ABCA1 expression and activity in human NPC1(-/-) fibroblasts, as indicated by near normalization of efflux of radiolabeled phosphatidylcholine and a marked increase in efflux of cholesterol mass to apoA-I. LXR agonist treatment prior to and during apoA-I incubation resulted in reduction in filipin staining of unesterified cholesterol in late endosomes/lysosomes, as well as cholesterol mass, in NPC1(-/-) cells. HDL species in human NPC disease plasma showed the same pattern of diminished large, cholesterol-rich alpha-1 HDL particles as seen in isolated heterozygous ABCA1 deficiency. Incubating NPC1(-/-) fibroblasts with the LXR agonist normalized the pattern of HDL particle formation by these cells. ABCG1, another LXR target gene involved in cholesterol efflux to HDL, also showed diminished expression in NPC1(-/-) fibroblasts and increased expression upon LXR agonist treatment. These results suggest that NPC1 mutations can be largely bypassed and that NPC1 protein function is non-essential for the trafficking and removal of cellular cholesterol if the down-stream defects in ABCA1 and ABCG1 regulation in NPC disease cells are corrected using an LXR agonist.

Introduction: Ezetimibe (EZ) is a selective cholesterol absorption inhibitor approved for use in Canada. The effect and tolerability of EZ among patients was evaluated in the clinical setting of a specialty cardiovascular risk reduction clinic at the University of Alberta Hospital, Edmonton, Alberta. patients and, Methods: All patients 18 years of age or older who were prescribed EZ were included, unless they failed to take EZ for a minimum of two weeks, did not have baseline and on-EZ low-density lipoprotein cholesterol (LDL-C) levels, or had concomitant lipid-lowering drugs or dosages changed within one month of starting EZ., Results: Eighty-four patients (mean age 57.9 years) were included. By Framingham risk calculation, 71.4% were found to be high-risk patients, 13.1% moderate-risk patients and 15.5% low-risk patients; 66.7% of patients had prior cardiovascular events. On EZ, the mean reductions were: total cholesterol level 1.11 mmol/L (16.5%); LDL-C level 1.01 mmol/L (22.3%); high-density lipoprotein cholesterol level 0.06 mmol/L (4.6%); and ratio of total cholesterol level to high-density lipoprotein cholesterol level 0.68 mmol/L (12.8%); all were statistically significant (P<0.001). Results were similar when stratified by primary (n=28) versus secondary (n=56) prevention. Patients on EZ monotherapy (n=34) had mean LDL-C reductions of 1.03 mmol/L (20.5%) compared with 1.19 mmol/L (30.1%) or 0.95 mmol/L (22.5%), where EZ was added to low-dose or high-dose statins (P<0.01 for all). On EZ, 30 patients (35.7%) achieved previously unattainable target LDL-C levels. Four patients discontinued the drug due to side effects., Conclusions: EZ is safe and effective in high-risk patients treated in the clinical setting of a cardiovascular risk reduction clinic. A mean LDL-C reduction of 1 mmol/L (20% to 30%) in all patient subgroups is consistent with previous clinical trial results. The significant reduction in LDL-C (mean 22.5%) observed in the EZ plus high-dose statin subgroup provides clinical evidence for use of this medication beyond published studies.

The membrane transporter ATP-binding cassette transporter A1 (ABCA1) has been shown to be the rate-limiting step in the initial formation of plasma high-density lipoprotein (HDL) particles. The mechanisms of action of ABCA1, including its role in the vesicular transport of lipids to the cell surface for the lipidation of HDL apolipoproteins, are not fully understood. Niemann-Pick type C (NPC) disease is most often caused by mutations in the NPC1 gene, whose protein product is believed to facilitate the egress of cholesterol and other lipids from late endosomes and lysosomes to other cellular compartments. This report reviews current knowledge regarding the role of ABCA1 in vesicular lipid transport mechanisms required for HDL particle formation, and the relationship between ABCA1 and NPC1 in this process.

Background: Familial partial lipodystrophy (Dunnigan) type 3 (FPLD3, Mendelian Inheritance in Man [MIM] 604367) results from heterozygous mutations in PPARG encoding peroxisomal proliferator-activated receptor-gamma. Both dominant-negative and haploinsufficiency mechanisms have been suggested for this condition., Methods: We present a Canadian FPLD3 kindred with an affected mother who had loss of fat on arms and legs, but no increase in facial, neck, suprascapular or abdominal fat. She had profound insulin resistance, diabetes, severe hypertriglyceridemia and relapsing pancreatitis, while her pre-pubescent daughter had normal fat distribution but elevated plasma triglycerides and C-peptide and depressed high-density lipoprotein cholesterol., Results: The mother and daughter were each heterozygous for PPARG nonsense mutation Y355X, whose protein product in vitro was transcriptionally inactive with no dominant-negative activity against the wild-type receptor. In addition the mutant protein appeared to be markedly unstable., Conclusion: Taken together with previous studies of human PPARG mutations, these findings suggest that PPAR-gamma deficiency due either to haploinsufficiency or to substantial activity loss due to dominant negative interference of the normal allele product's function can each contribute to the FPLD3 phenotype.

Background: Debate continues concerning the relevance of neutralizing antibody (NAb) development on the efficacy of interferon (IFN) therapy in patients with multiple sclerosis (MS). The PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) Study of subcutaneous IFNbeta-1a showed significant benefit on all efficacy outcomes with no significant impact from NAb development on relapses at 2 years. The 2-year extension permitted longer observation following NAb development., Methods: Exploratory post-hoc analyses of pharmacodynamic response and clinical and MRI outcomes were performed on data from 368 patients with relapsing MS treated with IFN from study start, based on NAb status., Results: Persistent NAbs, above 20 NU/mL, were present in 14% of the 44-microg three times weekly (TIW) and 24% of the 22-microg TIW group over 4 years. NAb development was associated with reduced pharmacodynamic marker induction at 1 year. Over the entire 4 years of study, relapse and disability measures were similar between NAb+ and NAb- patients. However, once NAbs developed, significant differences were noted between NAb+ and NAb- groups, particularly on MRI and relapse measures. The presence of binding antibodies alone did not affect outcome., Conclusion: Neutralizing antibody development in interferon-treated patients is correlated with reduced efficacy and is a potential cause for renewed disease activity.

The removal of phospholipids and cholesterol from tissues is the major mechanism mediating the initial assembly of high density lipoproteins (HDL), as well as being the main reason HDL are thought to protect against atherosclerosis. Investigations of the mechanisms of HDL assembly and testing of novel HDL-raising agents typically involve assays to determine phospholipid and/or cholesterol removal or "efflux" from cultured cells. The purpose of this chapter is to describe experimental protocols that can be used in the determination of cholesterol and phospholipid efflux from cultured cells by HDL apolipoproteins for the formation of new HDL particles, and the testing of novel HDL-raising therapies in vitro. A protocol is also provided for determining the size and nature of HDL particles formed in cell-conditioned medium using two-dimensional gel electrophoresis.

NPC (Niemann-Pick type C) disease is a progressive neurological disorder characterized by defects in intracellular cholesterol trafficking, accumulation of cholesterol in the endosomal system and impaired cholesterol homoeostasis. Although these alterations appear to occur in all NPC1-deficient cell types, the consequences are most profound in the nervous system. Since glial cells are important mediators of brain cholesterol homoeostasis, we proposed that defective generation and/or function of lipoproteins released by glia might contribute to the neurological abnormalities associated with NPC disease. We found that, as in other cell types, Npc1-/- glia accumulate cholesterol intracellularly. We hypothesized that this sequestration of cholesterol in glia might restrict the availability of cholesterol for lipoprotein production. Cerebellar astroglia were cultured from a murine model of NPC disease to compare the lipoproteins generated by these cells and wild-type glia. The experiments demonstrate that the amount of cholesterol in glia-conditioned medium is not reduced by NPC1 deficiency. Similarly, cholesterol efflux to apo (apolipoprotein) A1 or glial expression of the transporter ATP-binding-cassette transporter A1 was not decreased by NPC1 deficiency. In addition, the ratio of apo E:cholesterol and the density distribution of lipoproteins in Npc1-/- and Npc1+/+ glia-conditioned medium are indistinguishable. Importantly, in a functional assay, apo E-containing lipoproteins generated by Npc1-/- and Npc1+/+ glia each stimulate axonal elongation of neurons by approx. 35%. On the basis of these observations, we speculate that the neuropathology characteristic of NPC disease can quite probably be ascribed to impaired processes within neurons in the brain rather than defective lipoprotein production by astroglia.

Background: The EVIDENCE (Evidence of Interferon Dose-Response: European North American Comparative Efficacy) Study demonstrated that patients with multiple sclerosis (MS) who initiate interferon beta-1a therapy with 44 microg 3 times weekly (TIW) were less likely to have a relapse or activity on magnetic resonance imaging (MRI) compared with those who initiate therapy at a dosage of 30 microg 1 time weekly (QW)., Objective: To determine the effect of changing the dosage from 30 microg QW to 44 microg TIW in this extension of the EVIDENCE Study., Design/patients: Patients with relapsing MS originally randomized to interferon beta-1a, 30 microg QW, during the comparative phase of the study changed to 44 microg TIW, whereas patients originally randomized to 44 microg TIW continued that regimen. Patients were followed up, on average, for an additional 32 weeks., Main Outcome Measure: The within-patient pretransition to post-transition change in relapse rate., Results: At the transition visit, 223 (73%) of 306 patients receiving 30 microg QW converted to 44 microg TIW, and 272 (91%) of 299 receiving 44-microg TIW continued the same therapy. The post-transition annualized relapse rate decreased from 0.64 to 0.32 for patients increasing the dose (P<.001) and from 0.46 to 0.34 for patients continuing 44-microg TIW (P = .03). The change was greater in those increasing dose and frequency (P = .047). Patients converting to the 44-mug TIW regimen had fewer active lesions on T2-weighted MRI compared with before the transition (P = .02), whereas those continuing the 44-microg TIW regimen had no significant change in T2 active lesions. Patients who converted to high-dose/high-frequency interferon beta-1a therapy had increased rates of adverse events and treatment terminations consistent with the initiation of high-dose subcutaneous interferon therapy., Conclusions: Patients receiving interferon beta-1a improved on clinical and MRI disease measures when they changed from 30 microg QW to 44 microg TIW.

It has been suggested that interferons (IFN) may cause depression de novo or worsen pre-existing depression. Depression data collected using validated instruments from individual clinical trials in multiple sclerosis, however, have consistently failed to identify an association. In this study, pooled data from 6 controlled studies and 17 noncontrolled clinical trials of subcutaneous IFN beta-1a were assessed to determine the relationship between IFN therapy with physician reports of depression and suicide. In distinction to the negative findings for depressive symptom ratings, pooling of physician-reported side effect data from these clinical trials identified a statistically significant association between depression and IFN use during the first six months of treatment There was an association between these reported episodes of depression and discontinuation of IFN therapy, but IFN treatment was not associated with suicide attempts. IFN beta-1a may induce a constellation of symptoms, particularly early in therapy, that may be labelled as depression by physicians. However, the lack of an increase in depression-rating scale scores and the lack of association with suicide risk suggests that the syndrome may be an atypical one.

Familial hypercholesterolemia (FH) is characterized by the accumulation of excess cholesterol in tissues including the artery wall and tendons. We describe a patient with homozygous FH who presented with asymptomatic cholesterol granuloma of the brain. The patient's plasma low-density lipoprotein cholesterol level was remarkably responsive to combination hypolipidemic therapy with statin plus ezetimibe. This case illustrates another potential complication of whole-body cholesterol excess and underscores the differences in phenotype and in response to therapy among patients with FH.

Interferon (IFN) beta has been shown to be an effective therapy in pivotal studies of multiple sclerosis (MS), with differences in outcomes based on dose and/or frequency of administration. Glatiramer acetate (GA) has also shown to have an effect on relapses and magnetic resonance imaging measures, but not on disability. All products are associated with adverse events, and utilisation of a specific therapy needs to consider benefit in relation to risk. Evidence-based medicine provides a means of assessing benefit and risk in the context of the number of patients one needs to treat to obtain benefit (NNT) compared with the number needed to treat for an adverse outcome (NNH). Efficacy and safety data are presented from IFN beta-1a (Rebif) clinical trials, including relevant NNT and NNH values, to allow assessment of the overall benefit-to-risk ratio compared with placebo. Additional comparisons are made with published data for other IFN products and GA. The indirect comparative information reviewed demonstrates that IFN appears to have a better benefit- to-risk ratio than GA. Indirect comparisons suggest better efficacy of thrice weekly (tiw) IFN beta-1a compared with alternate-day IFN beta-1b, but no direct comparative data are available. Direct comparative data show that IFN beta-1a at a dose of 44 mcg tiw has a favourable benefit-to-risk ratio compared with both 22 mcg tiw and 30 mcg once weekly, suggesting that 44 mcg tiw currently has the best benefit- to-risk ratio for the treatment of relapsing MS.

Neutrophil degranulation is important in many inflammatory disorders, although the intracellular mechanisms underlying this process remain poorly understood. The Rho GTPase, Rac2, has been implicated in control of degranulation in earlier studies. We hypothesized that Rac2 selectively regulates neutrophil primary granule release. Using bone marrow and peritoneal exudate neutrophils from rac2(-/-) mice in comparison with similar cells from wild-type C57Bl/6 mice, we found that primary granule myeloperoxidase and elastase release was absent in Rac2(-/-) neutrophils in response to chemoattractant stimulation, cytochalasin B/f-Met-Leu-Phe (CB/fMLP), and CB/leukotriene B4. Rac2(-/-) neutrophils also failed to exhibit mobilization of the primary granule marker CD63+ during CB/fMLP stimulation as determined by confocal microscopy. Priming of Rac2(-/-) neutrophils with tumor necrosis factor (TNF) or by peritoneal elicitation did not rescue the defect in primary granule release. However, phosphorylation of p38 mitogen-activated protein (MAP) kinase in Rac2(-/-) neutrophils was evident in response to CB/fMLP and/or TNF. Primary granule density and morphology were normal in Rac2(-/-) neutrophils. Secondary specific and tertiary granule release, measured by lactoferrin immunoassay and zymography, was normal in response to CB/fMLP and adhesion to fibronectin. These findings suggest an obligatory role for Rac2 in regulation of primary granule release by neutrophils.

IFN-beta therapy has a central place in the management of relapsing multiple sclerosis, as demonstrated by the pivotal studies of three IFN-beta treatment regimens. However, questions remain concerning the optimal choice of preparation and dose regimen. The benefit-risk ratio for a given preparation is an important consideration in optimising treatment for an individual patient. Of the three IFN-beta preparations currently available, all have shown benefit on activity measures (relapses and active lesions apparent on magnetic resonance imaging), while benefit on progression measures (disability and total lesion burden) has been less consistent. Available data across studies suggest that dose and/or dose frequency are important determinants of efficacy, a finding supported by direct comparative data on different IFN-beta preparations. The added benefit of high-dose, high-frequency IFN-beta therapy is not achieved at the cost of compromised safety or tolerability, indicating that three-times-weekly treatment offers a superior benefit-risk ratio to once-weekly treatment. The potential advantages of IFN-beta therapy may be enhanced by regular monitoring of efficacy and safety in order to maintain patients on therapy beyond the first few months when side effects are most apparent.

High levels of expression of the ATP binding cassette transporter A1 (ABCA1) in the liver and the need to over- or underexpress hepatic ABCA1 to impact plasma HDL levels in mice suggest a major role of the liver in HDL formation and in determining circulating HDL levels. Cultured murine hepatocytes were used to examine the role of hepatic ABCA1 in mediating the lipidation of apolipoprotein A-I (apoA-I) for HDL particle formation. Exogenous apoA-I stimulated cholesterol efflux to the medium from wild-type hepatocytes, but not from ABCA1-deficient (abca1(-/-)) hepatocytes. ApoA-I induced the formation of new HDL particles and enhanced the lipidation of endogenously secreted murine apoA-I in ABCA1-expressing but not abca1(-/-) hepatocytes. ABCA1-dependent cholesterol mobilization to apoA-I increased new cholesterol synthesis, indicating depletion of the regulatory pool of hepatocyte cholesterol during HDL formation. Secretion of triacylglycerol and apoB was decreased following apoA-I incubation with ABCA1-expressing but not abca1(-/-) hepatocytes. These results support a major role for hepatocyte ABCA1 in generating a critical pool of HDL precursor particles that enhance further HDL generation and passive cholesterol mobilization in the periphery. The results also suggest that diversion of hepatocyte cholesterol into the "reverse" cholesterol transport pathway diminishes cholesterol availability for apoB-containing lipoprotein secretion by the liver.

Introduction: Interferon-beta-1a (Rebif) is an established treatment for relapsing-remitting multiple sclerosis (MS) and haematological changes are commonly reported in clinical trials of this agent. The combined clinical trial and postmarketing safety database for subcutaneous interferon-beta-1a (Rebif) allows a comprehensive, retrospective assessment of both common and infrequent haematological effects associated with interferon-beta therapy., Methods: Haematological laboratory abnormalities were analysed from six randomised, controlled clinical trials of subcutaneous interferon-beta-1a in MS, five of which were placebo-controlled. Treatment data were collected from 2482 patients for up to 6 months, 1178 patients for up to 2 years and 786 patients for up to 6 years. Total interferon-beta-1a doses ranged from 22 microg once weekly to 44 microg three times weekly. Postmarketing surveillance data were also analysed., Results: Treatment with interferon-beta-1a led to asymptomatic dose-related reductions in all cell lineages under investigation, predominantly white blood cells. The greatest differences between interferon-beta-1a therapy and placebo were seen for total leucocyte and neutrophil counts. At least two-thirds of patients affected by cytopenia experienced the onset of cytopenia within the first 6 months of therapy. The majority of events were mild and generally resolved within 3--4 months, while continuing therapy. Dose reductions were uncommon and only a small proportion (6 of 727; 0.8%) of patients stopped treatment over 2 years because of haematological abnormalities when receiving the highest dose of interferon-beta-1a, 44 microg three times weekly. Postmarketing safety reports were similarly related to asymptomatic cytopenias, although one case of potentially related autoimmune haemolytic anaemia was reported., Conclusion: Although haematological abnormalities are common and dose-related in patients with MS receiving interferon-beta-1a, the events are mainly mild and transient, with little impact on adherence to therapy. Haematological events are rarely of clinical significance and do not adversely affect the benefit-to-risk ratio that favours high-dose interferon-beta-1a therapy.

Objective: Tyrosyl radical-oxidized HDL (tyrHDL) increases the ability of cells to donate cholesterol to apolipoprotein (apo) A-I for HDL particle formation. We tested whether treatment with tyrHDL raises endogenous HDL cholesterol levels and decreases atherosclerosis development in apoE-deficient mice., Methods and Results: Tyrosyl radical oxidation of mouse HDL induced formation of apoAI-AII heterodimers and enhanced the ability of mouse HDL to deplete cultured fibroblasts of their regulatory pool of cholesterol. 125I-labeled HDL and tyrHDL delivered intraperitoneally were cleared at similar rates from plasma of chow-fed apoE-deficient mice. ApoE-deficient mice injected intraperitoneally twice weekly with 150 microg tyrHDL from age 10 to 18 weeks showed a maximum 2.3-fold increase in endogenous HDL cholesterol levels, which fell toward the end of the treatment period. tyrHDL treatment resulted in 37% less aortic lesion development than in control HDL-treated mice (P<0.001) and 67% less than in saline-injected animals (P<0.001)., Conclusions: Administration of tyrHDL for 8 weeks resulted in significantly less atherosclerosis development in apoE-deficient mice than injection of HDL or saline. Molecules increasing mobilization of cellular cholesterol to apoAI for HDL particle formation would be expected to decrease atherosclerosis without necessarily causing sustained increases in circulating HDL cholesterol levels.

The cholesterol trafficking defect in Niemann-Pick type C (NPC) disease leads to impaired regulation of cholesterol esterification, cholesterol synthesis, and low density lipoprotein receptor activity. The ATP-binding cassette transporter A1 (ABCA1), which mediates the rate-limiting step in high density lipoprotein (HDL) particle formation, is also regulated by cell cholesterol content. To determine whether the Niemann-Pick C1 protein alters the expression and activity of ABCA1, we determined the ability of apolipoprotein A-I (apoA-I) to deplete pools of cellular cholesterol and phospholipids in human fibroblasts derived from NPC1+/+, NPC1+/-, and NPC1-/- subjects. Efflux of low density lipoprotein-derived, non-lipoprotein, plasma membrane, and newly synthesized pools of cell cholesterol by apoA-I was diminished in NPC1-/- cells, as was efflux of phosphatidylcholine and sphingomyelin. NPC1+/- cells showed intermediate levels of lipid efflux compared with NPC1+/+ and NPC1-/- cells. Binding of apoA-I to cholesterol-loaded and non-cholesterol-loaded cells was highest for NPC1+/- cells, with NPC1+/+ and NPC1-/- cells showing similar levels of binding. ABCA1 mRNA and protein levels increased in response to cholesterol loading in NPC1+/+ and NPC1+/- cells but showed low levels at base line and in response to cholesterol loading in NPC1-/- cells. Consistent with impaired ABCA1-dependent lipid mobilization to apoA-I for HDL particle formation, we demonstrate for the first time decreased plasma HDL-cholesterol levels in 17 of 21 (81%) NPC1-/- subjects studied. These results indicate that the cholesterol trafficking defect in NPC disease results in reduced activity of ABCA1, which we suggest is responsible for the low HDL-cholesterol in the majority of NPC subjects and partially responsible for the overaccumulation of cellular lipids in this disorder.

Peroxisome proliferator-activated receptor (PPAR)-alpha is a member of a large nuclear receptor superfamily whose main role is to activate genes involved in fatty acid oxidation in the liver, heart, kidney, and skeletal muscle. While currently used mainly as hypolipidemic agents, the cardiac effects and anti-inflammatory actions of PPAR-alpha agonists in arterial wall cells suggest other potential cardioprotective and antiatherosclerotic effects of these agents. This review summarizes current knowledge regarding the effects of PPAR-alpha agonists on lipid and lipoprotein metabolism, the heart, and the vessel wall and introduces some of the insights gained in these areas from studying PPAR-alpha-deficient mice. The introduction of new and more potent PPAR-alpha agonists will provide important insights into the overall benefits of activating PPAR-alpha clinically for the treatment of dyslipidemia and prevention of vascular disease.

In the recently proposed diagnostic criteria for multiple sclerosis (MS) by McDonald, the modified magnetic resonance imaging (MRI) Barkhof criteria have been incorporated. We examined the validity of this implementation in the Early Treatment of MS study, a randomized, double-blind, placebo-controlled study of 22 microg interferon beta1a given subcutaneously once weekly in 309 patients with a first episode consistent with demyelinating disease (and abnormal MRI). Conversion to clinically definite MS (CDMS) within 2 years of follow-up, as evidenced by a new clinical episode, occurred in 41% of patients (independent of treatment) with gadolinium enhancement or nine or more T2 lesions versus 11% of those without either finding (p = 0.017); similarly, proportions converting were 44% versus 31% for infratentorial lesions (p = 0.026), 40% versus 35% for juxtacortical lesions (p = 0.413), and 41% versus 17% for three or more periventricular lesions (p = 0.034). The rate of conversion to CDMS based on the number of modified Barkhof criteria was 22% for two or fewer positive criteria, increasing to 47% with four positive criteria. For a cutoff of three positive criteria, the hazard ratio for time to CDMS was 2.3 (95% confidence interval, 1.17-4.55; p = 0.016). Treatment effect seemed more evident as the number of positive criteria increased, and the number of patients needed to avoid one patient converting to CDMS decreased from 50 in patients with one or two positive criteria to 5.6 in patients with four positive criteria. However, the study was not powered to detect statistically significant treatment by variable interaction, and this remains an important issue for further study.

Current treatment for atherosclerotic heart disease consists mainly of the administration of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors or 'statin' class of drugs. Statins, which lower low-density lipoprotein cholesterol levels and have numerous other effects in the arterial wall, have shown remarkable efficacy and an exemplary safety profile in preventing both primary and secondary atherosclerotic events. These agents, however, are less effective at raising high-density lipoprotein, lowering triglycerides and decreasing insulin resistance--all of which are important targets for the prevention of ischemic vascular disease. Agonists of the peroxisome proliferator-activated receptors (PPARs) are among the most promising drug candidates to target these treatment gaps. Only PPARalpha agonists have been shown clinically to improve the outcome of atherosclerotic heart disease; however, it will only be a matter of time before we know whether compounds that modulate the function of PPARgamma and beta/delta are also efficacious at combating atherosclerosis.

Background: Hepatic dysfunction, manifested as liver enzyme elevations, occurs frequently in patients who are treated with interferon, however, data for patients with multiple sclerosis are limited., Objective: To retrospectively assess the safety profile of interferon-beta-1a therapy with respect to liver function during clinical trials and postmarketing surveillance in the treatment of multiple sclerosis., Patients and Methods: Adverse effects and laboratory abnormalities were analysed from six randomised, controlled clinical trials (five of which were placebo-controlled) that assessed the use of interferon-beta-1a in patients with multiple sclerosis. Treatment data were collected for 2819 patients for up to 12 months, of whom 1995 received interferon-beta-1a (337 [12%] received Avonex intramuscular therapy, and 1658 [59%] received Rebif subcutaneous therapy), and 824 (29%) received placebo. Data for 2 years were collated for 1178 patients (from two studies). Total weekly interferon doses were 22-132 microg. Postmarketing surveillance data were also analysed., Results: In patients receiving interferon-beta-1a, there were significant elevations of alanine aminotransferase (ALT) levels, of all grades of severity, in up to 59% of patients at 6 months, up to 64% of patients at 12 months and up to 67% of patients at 24 months; ALT elevations were asymptomatic and dose related. More than 50% of elevations in liver enzymes occurred during the first 3 months of treatment, and more than 75% occurred during the first 6 months. Elevated enzyme levels resolved spontaneously or with dosage adjustment. Although the overall incidence of liver enzyme elevation was high during the early months of therapy, after 2 years, the proportion of patients with abnormal liver enzyme levels was 11% of those receiving Rebif 44 microg three times weekly compared with 6% of placebo-treated patients. Only 0.4% of patients discontinued interferon-beta-1a treatment because of hepatic adverse effects. Serious symptomatic interferon-related hepatic toxicity occurs, but is uncommon. Concomitant medication use was not associated with increased risk., Conclusion: Asymptomatic hepatic dysfunction is common in patients with multiple sclerosis who are treated with interferon-beta-1a, and is dose related. Adverse effects are mainly mild and transient, with little impact on adherence to therapy, although rare serious events can occur. Regular liver function monitoring during the first 6 months is recommended.

The metabolic nuclear receptors act as metabolic and toxicological sensors, enabling the organism to quickly adapt to environmental changes by inducing the appropriate metabolic genes and pathways. Ligands for these metabolic receptors are compounds from dietary origin, intermediates in metabolic pathways, drugs, or other environmental factors that, unlike classical nuclear receptor ligands, are present in high concentrations. Metabolic receptors are master regulators integrating the homeostatic control of (a) energy and glucose metabolism through peroxisome proliferator-activated receptor gamma (PPARgamma); (b) fatty acid, triglyceride, and lipoprotein metabolism via PPARalpha, beta/delta, and gamma; (c) reverse cholesterol transport and cholesterol absorption through the liver X receptors (LXRs) and liver receptor homolog-1 (LRH-1); (d) bile acid metabolism through the farnesol X receptor (FXR), LXRs, LRH-1; and (e) the defense against xeno- and endobiotics by the pregnane X receptor/steroid and xenobiotic receptor (PXR/SXR). The transcriptional control of these metabolic circuits requires coordination between these metabolic receptors and other transcription factors and coregulators. Altered signaling by this subset of receptors, either through chronic ligand excess or genetic factors, may cause an imbalance in these homeostatic circuits and contribute to the pathogenesis of common metabolic diseases such as obesity, insulin resistance and type 2 diabetes, hyperlipidemia and atherosclerosis, and gallbladder disease. Further studies should exploit the fact that many of these nuclear receptors are designed to respond to small molecules and turn them into therapeutic targets for the treatment of these disorders.

The Niemann-Pick C1 (NPC1) protein regulates cholesterol transport from late endosomes-lysosomes to other intracellular compartments. In this article, cholesterol transport to caveolin-1 and caveolin-2 containing compartments, such as the trans-Golgi network (TGN) and plasma membrane caveolae, was examined in normal (NPC+/+), NPC heterozygous (NPC+/-), and NPC homozygous (NPC-/-) human fibroblasts. The expression and distribution of NPC1 in each cell type were similar, and characterized by a finely dispersed, granular staining pattern. The expression of caveolin-1 and caveolin-2 was increased in NPC+/- and NPC-/- fibroblasts, although the distribution in each cell type was similar and characterized by predominant staining of the TGN and plasma membrane. The TGN in NPC+/+ fibroblasts was relatively cholesterol-enriched, whereas the TGN in NPC+/- and NPC-/- fibroblasts was partially or completely cholesterol-deficient, respectively. Consistent with studies demonstrating the transport of cholesterol from the TGN to plasma membrane caveolae, the concentration of cholesterol in plasma membrane caveolae isolated from NPC+/- and NPC-/- fibroblasts was significantly decreased, even though the total concentration of plasma membrane cholesterol in each cell type was similar. These studies demonstrate that NPC1 regulates cholesterol transport to caveolin-1 and caveolin-2 containing compartments such as the TGN and plasma membrane caveolae.

Achieving recommended cholesterol and triglyceride targets for the prevention of cardiovascular events is difficult and frequently requires the use of >1 lipid-lowering medication. This study evaluated the tolerability and effectiveness of combination regimens in high-risk dyslipidemic patients resistant to monotherapy. A retrospective chart review of all patients referred to a cardiovascular risk reduction clinic over a 7.5-year period identified 136 patients who received combination therapy with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) plus fibrate (n = 106) or a statin plus niacin (n = 30) regimen. During follow-up (mean 18.5 months), 28 patients (20.6%) discontinued combination therapy: 11 (8.1%) experienced myalgia with or without elevated creatine kinase, 3 had gastrointestinal upset, and 1 had asymptomatic creatine kinase elevation. No patient had combination therapy discontinued due to elevated liver enzymes. Medications were stopped in 8 patients for reasons other than reported adverse effects or biochemical abnormalities, and 5 patients were switched to alternate monotherapy. Mean percent change from baseline to treatment with combination therapy for total cholesterol (-35%), low-density lipoprotein cholesterol (-37%), high-density lipoprotein cholesterol (+23%), triglycerides (-62%), and total cholesterol/high-density lipoprotein cholesterol ratio (-41%) were all statistically significant (p <0.01). These results demonstrate that combination statin-fibrate and statin-niacin regimens are safe and effective in managing dyslipidemias in most patients at risk for cardiovascular events who are inadequately treated with one of these agents alone.