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Chang TY, Chang CCY, Harned TC, De La Torre AL, Lee J, Huynh TN, Gow JG. Blocking cholesterol storage to treat Alzheimer's disease. Explor Neuroprotective Ther 2021; 1:173-184. [PMID: 35199105 PMCID: PMC8863366 DOI: 10.37349/ent.2021.00014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cholesterol serves as an essential lipid molecule in various membrane organelles of mammalian cells. The metabolites of cholesterol also play important functions. Acyl-coenzyme A: cholesterol acyltransferase 1 (ACAT1), also named as sterol O-acyltransferase 1, is a membrane-bound enzyme residing at the endoplasmic reticulum (ER). It converts cholesterol to cholesteryl esters (CEs) for storage, and is expressed in all cells. CEs cannot partition in membranes; they can only coalesce as cytosolic lipid droplets. Excess CEs are found in the vulnerable region of the brains of patients with late-onset Alzheimer's disease (AD), and in cell and mouse models for AD. Reducing CE contents by genetic inactivation of ACAT1, or by pharmacological inhibition of ACAT is shown to reduce amyloidopathy and other hallmarks for AD. To account for the various beneficial actions of the ACAT1 blockade (A1B), a working hypothesis is proposed here: the increase in CE contents observed in the AD brain is caused by damages of cholesterol-rich lipid rafts that are known to occur in neurons affected by AD. These damages cause cholesterol to release from lipid rafts and move to the ER where it will be converted to CEs by ACAT1. In addition, the increase in CE contents may also be caused by overloading with cholesterol-rich substances, or through activation of ACAT1 gene expression by various proinflammatory agents. Both scenarios may occur in microglia of the chronically inflamed brain. A1B ameliorates AD by diverting the cholesterol pool destined for CE biosynthesis such that it can be utilized more efficiently to repair membrane damage in various organelles, and to exert regulatory actions more effectively to defend against AD. To test the validity of the A1B hypothesis in cell culture and in vivo, the current status of various anti-ACAT1 agents that could be further developed is briefly discussed.
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Affiliation(s)
- Ta Yuan Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Catherine C Y Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Taylor C Harned
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Adrianna L De La Torre
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Junghoon Lee
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Thao N Huynh
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - James G Gow
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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Labbaci FZ, Boukortt FO. Beneficial Effects of Algerian Green Alga Ulva lactuca and Its Hydroethanolic Extract on Insulin Resistance and Cholesterol Reverse Transport in High-Fat/Streptozotocin Diabetic Rats. Prev Nutr Food Sci 2020; 25:353-361. [PMID: 33505929 PMCID: PMC7813591 DOI: 10.3746/pnf.2020.25.4.353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/01/2020] [Indexed: 11/06/2022] Open
Abstract
The aim of this study was to evaluate the impact of the green algae Ulva lactuca and its hydroethanolic extract on insulin resistance and cholesterol reverse transport in type 2 diabetic (T2D) rats. Rats had T2D induced by a high-fat diet (HFD) for 5 weeks followed by intraperitoneal injection of streptozotocin. Diabetic rats were divided into three groups and were fed a HFD in the presence or absence of 1% alga (HFD-Alg) or 1% of its hydroethanolic extract (HFD-Ext), for 4 weeks. The control group consumed 20% casein combined with 5% lipids. Hyperglycemia, insulin resistance, hypercholesterolemia, and hypertriglyceridemia were noted in HFD rats vs control rats. Whole alga and its extract decreased these parameters vs the HFD. Moreover, fecal total cholesterol and triacylglycerols levels were lowered in HFD group vs C group, but were increased with HFD-Alg vs HFD. Compared with the Control, the HFD group had decreased lecithin:cholesterol acyltransferase (LCAT) activity, apolipoprotein A-I (ApoA-I), high-density lipoprotein (HDL3)-phospholipids (PL), and HDL2-cholesteryl ester (CE) levels, but increased HDL3-unesterified cholesterol (UC) levels. Furthermore, compared with the HFD group, the HFD-Alg and HFD-Ext groups had increased LCAT activity, ApoA-I, HDL3-PL, and HDL2-CE levels and decreased HDL3-UC levels. In addition, in the HFD-Ext group, LCAT activity and ApoA-1 levels were decreased vs the HFD-Alg whereas HDL3-UC levels were increased. In conclusion, these results indicate that U. lactuca and its hydroethanolic extract have curative effect on T2D. Therefore, this alga could be considered a functional food supplement for the treatment and prevention of diabetes.
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Affiliation(s)
- Fatima Zohra Labbaci
- Laboratory of Clinical and Metabolic Nutrition, Faculty of Nature and Life Sciences, University Oran 1, Oran 31100, Algeria
| | - Farida Ouda Boukortt
- Laboratory of Clinical and Metabolic Nutrition, Faculty of Nature and Life Sciences, University Oran 1, Oran 31100, Algeria
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Amar MJA, Freeman LA, Nishida T, Sampson ML, Pryor M, Vaisman BL, Neufeld EB, Karathanasis SK, Remaley AT. LCAT protects against Lipoprotein-X formation in a murine model of drug-induced intrahepatic cholestasis. Pharmacol Res Perspect 2020; 8:e00554. [PMID: 31893124 PMCID: PMC6935572 DOI: 10.1002/prp2.554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022] Open
Abstract
Familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is a rare genetic disease characterized by low HDL-C levels, low plasma cholesterol esterification, and the formation of Lipoprotein-X (Lp-X), an abnormal cholesterol-rich lipoprotein particle. LCAT deficiency causes corneal opacities, normochromic normocytic anemia, and progressive renal disease due to Lp-X deposition in the glomeruli. Recombinant LCAT is being investigated as a potential therapy for this disorder. Several hepatic disorders, namely primary biliary cirrhosis, primary sclerosing cholangitis, cholestatic liver disease, and chronic alcoholism also develop Lp-X, which may contribute to the complications of these disorders. We aimed to test the hypothesis that an increase in plasma LCAT could prevent the formation of Lp-X in other diseases besides FLD. We generated a murine model of intrahepatic cholestasis in LCAT-deficient (KO), wild type (WT), and LCAT-transgenic (Tg) mice by gavaging mice with alpha-naphthylisothiocyanate (ANIT), a drug well known to induce intrahepatic cholestasis. Three days after the treatment, all mice developed hyperbilirubinemia and elevated liver function markers (ALT, AST, Alkaline Phosphatase). The presence of high levels of LCAT in the LCAT-Tg mice, however, prevented the formation of Lp-X and other plasma lipid abnormalities in WT and LCAT-KO mice. In addition, we demonstrated that multiple injections of recombinant human LCAT can prevent significant accumulation of Lp-X after ANIT treatment in WT mice. In summary, LCAT can protect against the formation of Lp-X in a murine model of cholestasis and thus recombinant LCAT could be a potential therapy to prevent the formation of Lp-X in other diseases besides FLD.
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Affiliation(s)
- Marcelo J. A. Amar
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Lita A. Freeman
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Takafumi Nishida
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Maureen L. Sampson
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Milton Pryor
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Boris L. Vaisman
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Edward B. Neufeld
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Sotirios K. Karathanasis
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
- Cardiovascular and Metabolic Disease SectionMedImmuneGaithersburgMDUSA
- NeoProgenBaltimoreMDUSA
| | - Alan T. Remaley
- Lipoprotein Metabolism SectionTranslational Vascular Medicine BranchNational Heart Lung and Blood InstituteNational Institutes of HealthBethesdaMDUSA
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Ossoli A, Simonelli S, Varrenti M, Morici N, Oliva F, Stucchi M, Gomaraschi M, Strazzella A, Arnaboldi L, Thomas MJ, Sorci-Thomas MG, Corsini A, Veglia F, Franceschini G, Karathanasis SK, Calabresi L. Recombinant LCAT (Lecithin: Cholesterol Acyltransferase) Rescues Defective HDL (High-Density Lipoprotein)-Mediated Endothelial Protection in Acute Coronary Syndrome. Arterioscler Thromb Vasc Biol 2020; 39:915-924. [PMID: 30894011 DOI: 10.1161/atvbaha.118.311987] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Objective- Aim of this study was to evaluate changes in LCAT (lecithin:cholesterol acyltransferase) concentration and activity in patients with an acute coronary syndrome, to investigate if these changes are related to the compromised capacity of HDL (high-density lipoprotein) to promote endothelial nitric oxide (NO) production, and to assess if rhLCAT (recombinant human LCAT) can rescue the defective vasoprotective HDL function. Approach and Results- Thirty ST-segment-elevation myocardial infarction (STEMI) patients were enrolled, and plasma was collected at hospital admission, 48 and 72 hours thereafter, at hospital discharge, and at 30-day follow-up. Plasma LCAT concentration and activity were measured and related to the capacity of HDL to promote NO production in cultured endothelial cells. In vitro studies were performed in which STEMI patients' plasma was added with rhLCAT and HDL vasoprotective activity assessed by measuring NO production in endothelial cells. The plasma concentration of the LCAT enzyme significantly decreases during STEMI with a parallel significant reduction in LCAT activity. HDL isolated from STEMI patients progressively lose the capacity to promote NO production by endothelial cells, and the reduction is related to decreased LCAT concentration. In vitro incubation of STEMI patients' plasma with rhLCAT restores HDL ability to promote endothelial NO production, possibly related to significant modification in HDL phospholipid classes. Conclusions- Impairment of cholesterol esterification may be a major factor in the HDL dysfunction observed during acute coronary syndrome. rhLCAT is able to restore HDL-mediated NO production in vitro, suggesting LCAT as potential therapeutic target for restoring HDL functionality in acute coronary syndrome.
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Affiliation(s)
- Alice Ossoli
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
| | - Sara Simonelli
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
| | - Marisa Varrenti
- Cardiologia 1-Emodinamica, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy (M.V., N.M., F.O., M.S.).,Università degli Studi di Milano-Bicocca, Italy (M.V.)
| | - Nuccia Morici
- Department of Clinical Sciences and Community Health (N.M.), Università degli Studi di Milano, Italy.,Cardiologia 1-Emodinamica, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy (M.V., N.M., F.O., M.S.)
| | - Fabrizio Oliva
- Cardiologia 1-Emodinamica, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy (M.V., N.M., F.O., M.S.)
| | - Miriam Stucchi
- Cardiologia 1-Emodinamica, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy (M.V., N.M., F.O., M.S.)
| | - Monica Gomaraschi
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
| | - Arianna Strazzella
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
| | - Lorenzo Arnaboldi
- Dipartimento di Scienze Farmacologiche e Biomolecolari (L.A., A.C.), Università degli Studi di Milano, Italy
| | - Michael J Thomas
- Department of Pharmacology and Toxicology (M.J.T.), Medical College of Wisconsin, Milwaukee
| | - Mary G Sorci-Thomas
- Division of Endocrinology, Metabolism and Clinical Nutrition, Department of Medicine (M.G.S.-T.), Medical College of Wisconsin, Milwaukee
| | - Alberto Corsini
- Dipartimento di Scienze Farmacologiche e Biomolecolari (L.A., A.C.), Università degli Studi di Milano, Italy
| | | | - Guido Franceschini
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
| | | | - Laura Calabresi
- From the Centro E. Grossi Paoletti (A.O., S.S., M.G., A.S., G.F., L.C.), Università degli Studi di Milano, Italy
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