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Li J, Lu J, Wang M, Hu W, Jin N, Li X, Zhao B, Luo Q. Predictive Value of Second-Trimester Maternal Lipid Profiling in Early-Onset Pre-eclampsia: A Prospective Cohort Study and Nomogram. Front Med (Lausanne) 2021; 8:688312. [PMID: 34926481 PMCID: PMC8672138 DOI: 10.3389/fmed.2021.688312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: Maternal lipid profile in second trimester has rarely been investigated in the risk assessment for pre-eclampsia (PE). Since early-onset PE often companied by much worse clinical outcomes, thus, we aimed to evaluate the predictive value of second-trimester maternal lipid profiling for early-onset PE. Methods: A prospective cohort study was conducted to measure the second-trimester maternal lipid profile of pregnant women from January to December 2019. The pairwise association between maternal lipid profile and PE onset or pregnancy termination time was quantified. Multiple logistic regression was preformed to define risk factors for early-onset PE, and a nomogram for early-onset PE was developed. The net benefit of our model was evaluated by calibration curve and decision curve analyses. Results: We enrolled 5,908 pregnant women and they were divided into healthy (n = 5,789), late-onset PE (n = 64), and early-onset PE (n = 55) groups. Total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-c) were elevated in patients with PE, while high-density lipoprotein cholesterol (HDL-c) was decreased in patients with PE. TC, TG, and LDL-c were negatively correlated with PE onset time or gestational week at delivery. Receiver operating characteristic curves (ROC) defined the cutoff values of TG and HDL-c, and the final regression model included five statistically significant risk predictors for early-onset PE (maternal age of ≥35 years, multipara, pre-pregnancy body mass index (BMI) ≥25 kg/m2, second trimester TG ≥ 2.59 mmol/L and second trimester HDL-c ≤ 2.03 mmol/L. The nomogram had an excellent diagnostic performance (area under the curve = 0.912, sensitivity = 92.7%, and specificity = 76%) and was further validated with good calibration and positive net benefits in a decision curve analysis. Conclusions: An abnormally increased TG concentration and a decreased HDL-c concentration might serve as predictors of early-onset PE. Whether blood lipid-lowering measures can improve severe PE prognosis require further clarification.
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Affiliation(s)
- Juan Li
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Juefei Lu
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Mengni Wang
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wen Hu
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Neng Jin
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xingmiao Li
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Baihui Zhao
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Qiong Luo
- Department of Obstetrics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, China
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2
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Cooke AL, Morris J, Melchior JT, Street SE, Jerome WG, Huang R, Herr AB, Smith LE, Segrest JP, Remaley AT, Shah AS, Thompson TB, Davidson WS. A thumbwheel mechanism for APOA1 activation of LCAT activity in HDL. J Lipid Res 2018; 59:1244-1255. [PMID: 29773713 DOI: 10.1194/jlr.m085332] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/08/2018] [Indexed: 01/28/2023] Open
Abstract
APOA1 is the most abundant protein in HDL. It modulates interactions that affect HDL's cardioprotective functions, in part via its activation of the enzyme, LCAT. On nascent discoidal HDL, APOA1 comprises 10 α-helical repeats arranged in an anti-parallel stacked-ring structure that encapsulates a lipid bilayer. Previous chemical cross-linking studies suggested that these APOA1 rings can adopt at least two different orientations, or registries, with respect to each other; however, the functional impact of these structural changes is unknown. Here, we placed cysteine residues at locations predicted to form disulfide bonds in each orientation and then measured APOA1's ability to adopt the two registries during HDL particle formation. We found that most APOA1 oriented with the fifth helix of one molecule across from fifth helix of the other (5/5 helical registry), but a fraction adopted a 5/2 registry. Engineered HDLs that were locked in 5/5 or 5/2 registries by disulfide bonds equally promoted cholesterol efflux from macrophages, indicating functional particles. However, unlike the 5/5 registry or the WT, the 5/2 registry impaired LCAT cholesteryl esterification activity (P < 0.001), despite LCAT binding equally to all particles. Chemical cross-linking studies suggest that full LCAT activity requires a hybrid epitope composed of helices 5-7 on one APOA1 molecule and helices 3-4 on the other. Thus, APOA1 may use a reciprocating thumbwheel-like mechanism to activate HDL-remodeling proteins.
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Affiliation(s)
- Allison L Cooke
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Jamie Morris
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - John T Melchior
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - W Gray Jerome
- Departments of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Rong Huang
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Andrew B Herr
- Division of Immunobiology and Center for Systems Immunology Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Loren E Smith
- Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Jere P Segrest
- Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Thomas B Thompson
- Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, OH 45237
| | - W Sean Davidson
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
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3
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May-Zhang LS, Yermalitsky V, Huang J, Pleasent T, Borja MS, Oda MN, Jerome WG, Yancey PG, Linton MF, Davies SS. Modification by isolevuglandins, highly reactive γ-ketoaldehydes, deleteriously alters high-density lipoprotein structure and function. J Biol Chem 2018; 293:9176-9187. [PMID: 29712723 DOI: 10.1074/jbc.ra117.001099] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/30/2018] [Indexed: 01/17/2023] Open
Abstract
Cardiovascular disease risk depends on high-density lipoprotein (HDL) function, not HDL-cholesterol. Isolevuglandins (IsoLGs) are lipid dicarbonyls that react with lysine residues of proteins and phosphatidylethanolamine. IsoLG adducts are elevated in atherosclerosis. The consequences of IsoLG modification of HDL have not been studied. We hypothesized that IsoLG modification of apoA-I deleteriously alters HDL function. We determined the effect of IsoLG on HDL structure-function and whether pentylpyridoxamine (PPM), a dicarbonyl scavenger, can preserve HDL function. IsoLG adducts in HDL derived from patients with familial hypercholesterolemia (n = 10, 233.4 ± 158.3 ng/mg) were found to be significantly higher than in healthy controls (n = 7, 90.1 ± 33.4 pg/mg protein). Further, HDL exposed to myeloperoxidase had elevated IsoLG-lysine adducts (5.7 ng/mg protein) compared with unexposed HDL (0.5 ng/mg protein). Preincubation with PPM reduced IsoLG-lysine adducts by 67%, whereas its inactive analogue pentylpyridoxine did not. The addition of IsoLG produced apoA-I and apoA-II cross-links beginning at 0.3 molar eq of IsoLG/mol of apoA-I (0.3 eq), whereas succinylaldehyde and 4-hydroxynonenal required 10 and 30 eq. IsoLG increased HDL size, generating a subpopulation of 16-23 nm. 1 eq of IsoLG decreased HDL-mediated [3H]cholesterol efflux from macrophages via ABCA1, which corresponded to a decrease in HDL-apoA-I exchange from 47.4% to only 24.8%. This suggests that IsoLG inhibits apoA-I from disassociating from HDL to interact with ABCA1. The addition of 0.3 eq of IsoLG ablated HDL's ability to inhibit LPS-stimulated cytokine expression by macrophages and increased IL-1β expression by 3.5-fold. The structural-functional effects were partially rescued with PPM scavenging.
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Affiliation(s)
- Linda S May-Zhang
- From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-6602
| | - Valery Yermalitsky
- From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-6602
| | - Jiansheng Huang
- the Division of Cardiovascular Medicine, Department of Medicine, and
| | | | - Mark S Borja
- the Department of Chemistry and Biochemistry, California State University East Bay, Hayward, California 94542, and
| | - Michael N Oda
- the Children's Hospital Oakland Research Institute, Oakland, California 94609
| | - W Gray Jerome
- the Department of Pathology, Vanderbilt Medical Center, Nashville, Tennessee 37232
| | - Patricia G Yancey
- the Division of Cardiovascular Medicine, Department of Medicine, and
| | - MacRae F Linton
- From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-6602.,the Division of Cardiovascular Medicine, Department of Medicine, and
| | - Sean S Davies
- From the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-6602,
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4
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Melchior JT, Street SE, Andraski AB, Furtado JD, Sacks FM, Shute RL, Greve EI, Swertfeger DK, Li H, Shah AS, Lu LJ, Davidson WS. Apolipoprotein A-II alters the proteome of human lipoproteins and enhances cholesterol efflux from ABCA1. J Lipid Res 2017; 58:1374-1385. [PMID: 28476857 DOI: 10.1194/jlr.m075382] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/25/2017] [Indexed: 12/25/2022] Open
Abstract
HDLs are a family of heterogeneous particles that vary in size, composition, and function. The structure of most HDLs is maintained by two scaffold proteins, apoA-I and apoA-II, but up to 95 other "accessory" proteins have been found associated with the particles. Recent evidence suggests that these accessory proteins are distributed across various subspecies and drive specific biological functions. Unfortunately, our understanding of the molecular composition of such subspecies is limited. To begin to address this issue, we separated human plasma and HDL isolated by ultracentrifugation (UC-HDL) into particles with apoA-I and no apoA-II (LpA-I) and those with both apoA-I and apoA-II (LpA-I/A-II). MS studies revealed distinct differences between the subfractions. LpA-I exhibited significantly more protein diversity than LpA-I/A-II when isolated directly from plasma. However, this difference was lost in UC-HDL. Most LpA-I/A-II accessory proteins were associated with lipid transport pathways, whereas those in LpA-I were associated with inflammatory response, hemostasis, immune response, metal ion binding, and protease inhibition. We found that the presence of apoA-II enhanced ABCA1-mediated efflux compared with LpA-I particles. This effect was independent of the accessory protein signature suggesting that apoA-II induces a structural change in apoA-I in HDLs.
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Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Allison B Andraski
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Jeremy D Furtado
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Frank M Sacks
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115; Department of Genetics & Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Rebecca L Shute
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Emily I Greve
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Debi K Swertfeger
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Hailong Li
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - L Jason Lu
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237.
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5
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Gomaraschi M, Ossoli A, Castelnuovo S, Simonelli S, Pavanello C, Balzarotti G, Arca M, Di Costanzo A, Sampietro T, Vaudo G, Baldassarre D, Veglia F, Franceschini G, Calabresi L. Depletion in LpA-I:A-II particles enhances HDL-mediated endothelial protection in familial LCAT deficiency. J Lipid Res 2017; 58:994-1001. [PMID: 28351888 DOI: 10.1194/jlr.p072371] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/04/2017] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to evaluate the vasoprotective effects of HDL isolated from carriers of LCAT deficiency, which are characterized by a selective depletion of LpA-I:A-II particles and predominance of preβ migrating HDL. HDLs were isolated from LCAT-deficient carriers and tested in vitro for their capacity to promote NO production and to inhibit vascular cell adhesion molecule-1 (VCAM-1) expression in cultured endothelial cells. HDLs from carriers were more effective than control HDLs in promoting eNOS activation with a gene-dose-dependent effect (PTrend = 0.048). As a consequence, NO production induced by HDL from carriers was significantly higher than that promoted by control HDL (1.63 ± 0.24-fold vs. 1.34 ± 0.07-fold, P = 0.031). HDLs from carriers were also more effective than control HDLs in inhibiting the expression of VCAM-1 (homozygotes, 65.0 ± 8.6%; heterozygotes, 53.1 ± 7.2%; controls, 44.4 ± 4.1%; PTrend = 0.0003). The increased efficiency of carrier HDL was likely due to the depletion in LpA-I:A-II particles. The in vitro findings might explain why carriers of LCAT deficiency showed flow-mediated vasodilation and plasma-soluble cell adhesion molecule concentrations comparable to controls, despite low HDL-cholesterol levels. These results indicate that selective depletion of apoA-II-containing HDL, as observed in carriers of LCAT deficiency, leads to an increased capacity of HDL to stimulate endothelial NO production, suggesting that changes in HDL apolipoprotein composition may be the target of therapeutic interventions designed to improve HDL functionality.
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Affiliation(s)
- Monica Gomaraschi
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
| | - Alice Ossoli
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
| | - Samuela Castelnuovo
- Centro Dislipidemie, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Sara Simonelli
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
| | - Chiara Pavanello
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
| | - Gloria Balzarotti
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
| | - Marcello Arca
- Atherosclerosis Center, Department of Internal Medicine and Allied Sciences, Sapienza University of Rome, Rome, Italy
| | - Alessia Di Costanzo
- Atherosclerosis Center, Department of Internal Medicine and Allied Sciences, Sapienza University of Rome, Rome, Italy
| | | | - Gaetano Vaudo
- Department of Medicine, University of Perugia, Perugia, Italy
| | | | | | - Guido Franceschini
- Section of Chemical and Biomolecular Sciences, DeFENS, Università degli Studi di Milano, Milano, Italy
| | - Laura Calabresi
- Centro E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari Università degli Studi di Milano, Milano, Italy
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6
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Cornelius RM, Macri J, Cornelius KM, Brash JL. Interactions of Apolipoproteins AI, AII, B and HDL, LDL, VLDL with Polyurethane and Polyurethane-PEO Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12087-12095. [PMID: 26513526 DOI: 10.1021/acs.langmuir.5b02688] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The lipoproteins (HDL, LDL, VLDL) are important components of blood present in high concentration. Surprisingly, their role in blood-biomaterial interactions has been largely ignored. In previous work apolipoprotein AI (the main protein component of HDL) was identified as a major constituent of protein layers adsorbed from plasma to biomaterials having a wide range of surface properties, and quantitative data on the adsorption of apo AI to a biomedical grade polyurethane were reported. In the present communication quantitative data on the adsorption of apo AI, apo AII and apoB (the latter being a constituent of LDL and VLDL), as well as the lipoprotein particles themselves (HDL, LDL, VLDL), to a biomedical segmented polyurethane (PU) with and without an additive containing poly(ethylene oxide) (material referred to as PEO) are reported. Using radiolabeled apo AI, apo AII, and apoB, adsorption levels on PU from buffer at a protein concentration of 50 μg/mL were found to be 0.34, 0.40, and 0.14 μg/cm(2) (12, 23, and 0.25 nmol/cm(2)) respectively. Adsorption to the PEO surface was <0.02 μg/cm(2) for all three apolipoproteins demonstrating the strong protein resistance of this material. In contrast to the apolipoproteins, significant amounts of the lipoproteins were found to adsorb to the PEO as well as to the PU surface. X-ray photoelectron spectra, following exposure of the surfaces to the lipoproteins, showed a strong phosphorus signal, confirming that adsorption had occurred. It therefore appears that a PEO-containing surface that is resistant to apolipoproteins may be less resistant to the corresponding lipoproteins.
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Affiliation(s)
- R M Cornelius
- Department of Chemical Engineering ‡Department of Pathology & Molecular Medicine §Department of Biology ∥School of Biomedical Engineering McMaster University Hamilton, Ontario Canada
| | - J Macri
- Department of Chemical Engineering ‡Department of Pathology & Molecular Medicine §Department of Biology ∥School of Biomedical Engineering McMaster University Hamilton, Ontario Canada
| | - K M Cornelius
- Department of Chemical Engineering ‡Department of Pathology & Molecular Medicine §Department of Biology ∥School of Biomedical Engineering McMaster University Hamilton, Ontario Canada
| | - J L Brash
- Department of Chemical Engineering ‡Department of Pathology & Molecular Medicine §Department of Biology ∥School of Biomedical Engineering McMaster University Hamilton, Ontario Canada
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7
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Affiliation(s)
- Gregory
F. Pirrone
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
| | - Roxana E. Iacob
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
| | - John R. Engen
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
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8
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Alexander ET, Phillips MC. Influence of apolipoprotein A-I and apolipoprotein A-II availability on nascent HDL heterogeneity. J Lipid Res 2013; 54:3464-70. [PMID: 24089247 DOI: 10.1194/jlr.m043109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
It is important to understand HDL heterogeneity because various subspecies possess different functionalities. To understand the origins of HDL heterogeneity arising from the existence of particles containing only apoA-I (LpA-I) and particles containing both apoA-I and apoA-II (LpA-I+A-II), we compared the abilities of both proteins to promote ABCA1-mediated efflux of cholesterol from HepG2 cells and form nascent HDL particles. When added separately, exogenous apoA-I and apoA-II were equally effective in promoting cholesterol efflux, although the resultant LpA-I and LpA-II particles had different sizes. When apoA-I and apoA-II were mixed together at initial molar ratios ranging from 1:1 to 16:1 to generate nascent LpA-I+A-II HDL particles, the particle size distribution altered, and the two proteins were incorporated into the nascent HDL in proportion to their initial ratio. Both proteins formed nascent HDL particles with equal efficiency, and the relative amounts of apoA-I and apoA-II incorporation were driven by mass action. The ratio of lipid-free apoA-I and apoA-II available at the surface of ABCA1-expressing cells is a major factor in determining the contents of these proteins in nascent HDL. Manipulation of this ratio provides a means of altering the relative distribution of LpA-I and LpA-I+A-II HDL particles.
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Affiliation(s)
- Eric T Alexander
- GI/Nutrition/Hepatology Division, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
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9
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Apolipoprotein A-II is a key regulatory factor of HDL metabolism as appears from studies with transgenic animals and clinical outcomes. Biochimie 2013; 96:56-66. [PMID: 24012775 DOI: 10.1016/j.biochi.2013.08.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/28/2013] [Indexed: 01/26/2023]
Abstract
The structure and metabolism of HDL are linked to their major apolipoproteins (apo) A-I and A-II. HDL metabolism is very dynamic and depends on the constant remodeling by lipases, lipid transfer proteins and receptors. HDL exert several cardioprotective effects, through their antioxidant and antiinflammatory capacities and through the stimulation of reverse cholesterol transport from extrahepatic tissues to the liver for excretion into bile. HDL also serve as plasma reservoir for C and E apolipoproteins, as transport vehicles for a great variety of proteins, and may have more physiological functions than previously recognized. In this review we will develop several aspects of HDL metabolism with emphasis on the structure/function of apo A-I and apo A-II. An important contribution to our understanding of the respective roles of apo A-I and apo A-II comes from studies using transgenic animal models that highlighted the stabilizatory role of apo A-II on HDL through inhibition of their remodeling by lipases. Clinical studies coupled with proteomic analyses revealed the presence of dysfunctional HDL in patients with cardiovascular disease. Beyond HDL cholesterol, a new notion is the functionality of HDL particles. In spite of abundant literature on HDL metabolic properties, a major question remains unanswered: which HDL particle(s) confer(s) protection against cardiovascular risk?
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10
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Phillips MC. New insights into the determination of HDL structure by apolipoproteins: Thematic review series: high density lipoprotein structure, function, and metabolism. J Lipid Res 2012; 54:2034-2048. [PMID: 23230082 DOI: 10.1194/jlr.r034025] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Apolipoprotein (apo)A-I is the principal protein component of HDL, and because of its conformational adaptability, it can stabilize all HDL subclasses. The amphipathic α-helix is the structural motif that enables apoA-I to achieve this functionality. In the lipid-free state, the helical segments unfold and refold in seconds and are located in the N-terminal two thirds of the molecule where they are loosely packed as a dynamic, four-helix bundle. The C-terminal third of the protein forms an intrinsically disordered domain that mediates initial binding to phospholipid surfaces, which occurs with coupled α-helix formation. The lipid affinity of apoA-I confers detergent-like properties; it can solubilize vesicular phospholipids to create discoidal HDL particles with diameters of approximately 10 nm. Such particles contain a segment of phospholipid bilayer and are stabilized by two apoA-I molecules that are arranged in an anti-parallel, double-belt conformation around the edge of the disc, shielding the hydrophobic phospholipid acyl chains from exposure to water. The apoA-I molecules are in a highly dynamic state, and they stabilize discoidal particles of different sizes by certain segments forming loops that detach reversibly from the particle surface. The flexible apoA-I molecule adapts to the surface of spherical HDL particles by bending and forming a stabilizing trefoil scaffold structure. The above characteristics of apoA-I enable it to partner with ABCA1 in mediating efflux of cellular phospholipid and cholesterol and formation of a heterogeneous population of nascent HDL particles. Novel insights into the structure-function relationships of apoA-I should help reveal mechanisms by which HDL subclass distribution can be manipulated.
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Affiliation(s)
- Michael C Phillips
- Lipid Research Group, Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
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11
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Gao X, Yuan S, Jayaraman S, Gursky O. Role of apolipoprotein A-II in the structure and remodeling of human high-density lipoprotein (HDL): protein conformational ensemble on HDL. Biochemistry 2012; 51:4633-41. [PMID: 22631438 DOI: 10.1021/bi300555d] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-density lipoproteins (HDL, or "good cholesterol") are heterogeneous nanoparticles that remove excess cell cholesterol and protect against atherosclerosis. The cardioprotective action of HDL and its major protein, apolipoprotein A-I (apoA-I), is well-established, yet the function of the second major protein, apolipoprotein A-II (apoA-II), is less clear. In this review, we postulate an ensemble of apolipoprotein conformations on various HDL. This ensemble is based on the crystal structure of Δ(185-243)apoA-I determined by Mei and Atkinson combined with the "double-hairpin" conformation of apoA-II(dimer) proposed in the cross-linking studies by Silva's team, and is supported by the wide array of low-resolution structural, biophysical, and biochemical data obtained by many teams over decades. The proposed conformational ensemble helps integrate and improve several existing HDL models, including the "buckle-belt" conformation of apoA-I on the midsize disks and the "trefoil/tetrafoil" arrangement on spherical HDL. This ensemble prompts us to hypothesize that endogenous apoA-II (i) helps confer lipid surface curvature during conversion of nascent discoidal HDL(A-I) and HDL(A-II) containing either apoA-I or apoA-II to mature spherical HDL(A-I/A-II) containing both proteins, and (ii) hinders remodeling of HDL(A-I/A-II) by hindering the expansion of the apoA-I conformation. Also, we report that, although endogenous apoA-II circulates mainly on the midsize spherical HDL(A-I/A-II), exogenous apoA-II can bind to HDL of any size, thereby slightly increasing this size and stabilizing the HDL assembly. This suggests distinctly different effects of the endogenous and exogenous apoA-II on HDL. Taken together, the existing results and models prompt us to postulate a new structural and functional role of apoA-II on human HDL.
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Affiliation(s)
- Xuan Gao
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
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12
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Sontag TJ, Carnemolla R, Vaisar T, Reardon CA, Getz GS. Naturally occurring variant of mouse apolipoprotein A-I alters the lipid and HDL association properties of the protein. J Lipid Res 2012; 53:951-963. [PMID: 22402133 DOI: 10.1194/jlr.m021154] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Plasma HDL levels are inversely associated with atherosclerosis. Inbred mouse strains differ in plasma HDL levels and susceptibility to atherosclerosis. Atherosclerosis-susceptible C57BL/6J mice possess plasma HDL levels 2-fold lower than atherosclerosis-resistant FVB/NJ mice. Polymorphisms have been previously identified between the two mouse strains in the major HDL apolipoproteins, ApoA-I and ApoA-II, which may affect their function on HDL. To begin to understand the HDL differences, we here report on a detailed comparison of the lipid-associated functions of the two mouse ApoA-I proteins. We demonstrate that these polymorphisms significantly alter the protein self-association properties, the ability of the proteins to clear lipid micelles from solution, and their binding affinity for mature mouse HDL. The changes in lipid binding do not appear to alter the ability of the protein to promote cholesterol efflux from cells or the formation of nascent HDL from primary hepatocytes. These apolipoprotein polymorphisms do not change the rate at which HDL protein or cholesterol are catabolized in vivo. Although the presence of the polymorphisms in ApoA-I alters important factors in HDL formation, the basis for the differences in the HDL plasma levels observed in the various mouse strains is more complex and requires additional investigation.
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Affiliation(s)
| | - Ronald Carnemolla
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA; and
| | - Tomas Vaisar
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA
| | | | - Godfrey S Getz
- Department of Pathology, University of Chicago, Chicago, IL.
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