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Ann Arbor, MI, United States

Gauthamadasa K.,University of Cincinnati | Vaitinadin N.S.,University of Cincinnati | Dressman J.L.,University of Cincinnati | Macha S.,University of Cincinnati | And 3 more authors.
Journal of Biological Chemistry

It is well accepted that HDL has the ability to reduce risks for several chronic diseases. To gain insights into the functional properties of HDL, it is critical to understand the HDL structure in detail. To understand interactions between the two major apolipoproteins (apos), apoA-I and apoA-II in HDL, we generated highly defined benchmark discoidal HDL particles. These particles were reconstituted using a physiologically relevant phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) incorporating two molecules of apoA-I and one homodimer of apoA-II per particle. We utilized two independent mass spectrometry techniques to study these particles. The techniques are both sensitive to protein conformation and interactions and are namely: 1) hydrogen deuterium exchange combined with mass spectrometry and 2) partial acetylation of lysine residues combined with MS. Comparison of mixed particles with apoA-I only particles of similar diameter revealed that the changes in apoA-I conformation in the presence of apoA-II are confined to apoA-I helices 3-4 and 7-9. We discuss these findings with respect to the relative reactivity of these two particle types toward a major plasma enzyme, lecithin:cholesterol acyl-transferase responsible for the HDL maturation process. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Source

Homan R.,AlphaCore Pharma | Hanselman J.C.,Esperion Therapeutics | Bak-Mueller S.,Pfizer | Lester P.,University of Michigan | And 4 more authors.

Objective: Animal models of atherosclerosis are essential to elucidate disease mechanisms and develop new therapies. Each model features advantages and disadvantages in exemplifying the pathophysiology of human atherosclerosis. Diet-induced development of atherosclerosis in Octodon degus (degu) was examined to demonstrate the potential of the degu as a model of human atherosclerosis. Methods: Degus were fed for 16 weeks with either normal chow or chow containing 0.25% cholesterol and 6% palm oil to induce atherosclerosis. The lipid compositions of plasma lipoproteins and aortas were determined. Locations of aortic lesions were mapped by imaging of fluorescently stained aortic lesions. Lesion morphology in the brachiocephalic artery was detected by histological staining. Results: Total plasma cholesterol in chow-fed degus was distributed approximately 60% in HDL, 30% in LDL and less than 10% in VLDL. Cholesterol-fed degus exhibited 4- to 5-fold increases in total plasma cholesterol, principally in the VLDL and LDL fractions. Cholesteryl ester transfer protein activity of similar magnitude to that in human plasma was detected in chow-fed degu plasma. Cholesterol-fed degus developed cholesteryl ester-rich atherosclerotic lesions throughout the aorta. Histological examination of lesions in the brachiocephalic artery showed well-formed, foam cell-rich lesions populated with inflammatory cells. It is also noteworthy that all the degus in this study exhibited hyperglycemia. Conclusion: These results demonstrate that degus have a human-like lipoprotein metabolism and develop extensive atherosclerosis with cholesterol feeding in the presence of hyperglycemia. These features, combined with the manageable size and handling characteristics, point to the potential of the degu as a useful model for atherosclerosis research. © 2010 Elsevier Ireland Ltd. Source

Krause B.R.,AlphaCore Pharma | Remaley A.T.,U.S. National Institutes of Health
Current Opinion in Lipidology

PURPOSE OF REVIEW: New therapeutic strategies are needed for the rapid stabilization of acute coronary syndrome (ACS) patients by treating nonculprit lesions. Reconstituted HDL (rHDL), which is apoA-I combined with phospholipids, is currently being tested in clinical trials for this purpose and is the subject of this review. RECENT FINDINGS: At least four different formulations (SRC-rHDL, CSL-111, CSL-112 and ETC-216) have been tested in clinical trials. The various rHDL preparations have been shown to be effective in the rapid mobilization of excess cholesterol from cells and in regressing atherosclerotic plaques in animal models. Two of the rHDL agents, namely ETC-216 and CSL-111, have been shown to be effective after only a few treatments in reducing plaque volume in ACS patients, as assessed by intravascular ultrasound, but no clinical trials assessing clinical endpoints have yet been completed. SUMMARY: rHDL is a promising new potential therapy for ACS patients, but much work remains to be done, and there are many unresolved questions. Progress in developing rHDL into a therapy will depend on improving our understanding of their mechanism of action, determining the optimum formulation and delivery and how to monitor rHDL therapy. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source

Homan R.,AlphaCore Pharma | Esmaeil N.,AlphaCore Pharma | Mendelsohn L.,U.S. National Institutes of Health | Kato G.J.,U.S. National Institutes of Health
Analytical Biochemistry

We describe a simple but sensitive fluorescence method to accurately detect the esterification activity of lecithin:Cholesterol acyltransferase (LCAT). The new assay protocol employs a convenient mix, incubate, and measure scheme. This is possible by using the fluorescent sterol dehydroergosterol (DHE) in place of cholesterol as the LCAT substrate. The assay method is further enhanced by incorporation of an amphiphilic peptide in place of apolipoprotein A-I as the lipid emulsifier and LCAT activator. Specific fluorescence detection of DHE ester synthesis is achieved by employing cholesterol oxidase to selectively render unesterified DHE nonfluorescent. The assay accurately detects LCAT activity in buffer and in plasma that is depleted of apolipoprotein B lipoproteins by selective precipitation. Analysis of LCAT activity in plasmas from control subjects and sickle cell disease (SCD) patients confirms previous reports of reduced LCAT activity in SCD and demonstrates a strong correlation between plasma LCAT activity and LCAT content. The fluorescent assay combines the sensitivity of radiochemical assays with the simplicity of nonradiochemical assays to obtain accurate and robust measurement of LCAT esterification activity. © 2013 Elsevier Inc. All rights reserved. Source

Shamburek R.D.,U.S. National Institutes of Health | Bakker-Arkema R.,AlphaCore Pharma | Bakker-Arkema R.,Med Immune Ltd. | Auerbach B.J.,AlphaCore Pharma | And 5 more authors.
Journal of Clinical Lipidology

Background Humans with familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) have extremely low or undetectable high-density lipoprotein cholesterol (HDL-C) levels and by early adulthood develop many manifestations of the disorder, including corneal opacities, anemia, and renal disease. Objective To determine if infusions of recombinant human LCAT (rhLCAT) could reverse the anemia, halt progression of renal disease, and normalize HDL in FLD. Methods rhLCAT (ACP-501) was infused intravenously over 1 hour on 3 occasions in a dose optimization phase (0.3, 3.0, and 9.0 mg/kg), then 3.0 or 9.0 mg/kg every 1 to 2 weeks for 7 months in a maintenance phase. Plasma lipoproteins, lipids, LCAT levels, and several measures of renal function and other clinical labs were monitored. Results LCAT concentration peaked at the end of each infusion and decreased to near baseline over 7 days. Renal function generally stabilized or improved and the anemia improved. After infusion, HDL-C rapidly increased, peaking near normal in 8 to 12 hours; analysis of HDL particles by various methods all revealed rapid sequential disappearance of preβ-HDL and small α-4 HDL and appearance of normal α-HDL. Low-density lipoprotein cholesterol increased more slowly than HDL-C. Of note, triglyceride routinely decreased after meals after infusion, in contrast to the usual postprandial increase in the absence of rhLCAT infusion. Conclusions rhLCAT infusions were well tolerated in this first-in-human study in FLD; the anemia improved, as did most parameters related to renal function in spite of advanced disease. Plasma lipids transiently normalized, and there was rapid sequential conversion of small preβ-HDL particles to mature spherical α-HDL particles. © 2016 National Lipid Association. Source

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