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Wang N, Ren L, Danser AHJ. Vacuolar H +-ATPase in Diabetes, Hypertension, and Atherosclerosis. Microcirculation 2024:e12855. [PMID: 38683673 DOI: 10.1111/micc.12855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/29/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024]
Abstract
Vacuolar H+-ATPase (V-ATPase) is a multisubunit protein complex which, along with its accessory proteins, resides in almost every eukaryotic cell. It acts as a proton pump and as such is responsible for regulating pH in lysosomes, endosomes, and the extracellular space. Moreover, V-ATPase has been implicated in receptor-mediated signaling. Although numerous studies have explored the role of V-ATPase in cancer, osteoporosis, and neurodegenerative diseases, research on its involvement in vascular disease remains limited. Vascular diseases pose significant challenges to human health. This review aimed to shed light on the role of V-ATPase in hypertension and atherosclerosis. Furthermore, given that vascular complications are major complications of diabetes, this review also discusses the pathways through which V-ATPase may contribute to such complications. Beginning with an overview of the structure and function of V-ATPase in hypertension, atherosclerosis, and diabetes, this review ends by exploring the pharmacological potential of targeting V-ATPase.
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Affiliation(s)
- Na Wang
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
- Clinical Research Center, The First Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Liwei Ren
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
- Department of Pharmacy, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, China
| | - A H Jan Danser
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
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2
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Skeyni A, Pradignac A, Matz RL, Terrand J, Boucher P. Cholesterol trafficking, lysosomal function, and atherosclerosis. Am J Physiol Cell Physiol 2024; 326:C473-C486. [PMID: 38145298 DOI: 10.1152/ajpcell.00415.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/17/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
Despite years of study and major research advances over the past 50 years, atherosclerotic diseases continue to rank as the leading global cause of death. Accumulation of cholesterol within the vascular wall remains the main problem and represents one of the early steps in the development of atherosclerotic lesions. There is a complex relationship between vesicular cholesterol transport and atherosclerosis, and abnormalities in cholesterol trafficking can contribute to the development and progression of the lesions. The dysregulation of vesicular cholesterol transport and lysosomal function fosters the buildup of cholesterol within various intracytoplasmic compartments, including lysosomes and lipid droplets. This, in turn, promotes the hallmark formation of foam cells, a defining feature of early atherosclerosis. Multiple cellular processes, encompassing endocytosis, exocytosis, intracellular trafficking, and autophagy, play crucial roles in influencing foam cell formation and atherosclerotic plaque stability. In this review, we highlight recent advances in the understanding of the intricate mechanisms of vesicular cholesterol transport and its relationship with atherosclerosis and discuss the importance of understanding these mechanisms in developing strategies to prevent or treat this prevalent cardiovascular disease.
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Affiliation(s)
- Alaa Skeyni
- UMR-S INSERM 1109, University of Strasbourg, Strasbourg, France
| | - Alain Pradignac
- UMR-S INSERM 1109, University of Strasbourg, Strasbourg, France
| | - Rachel L Matz
- UMR-S INSERM 1109, University of Strasbourg, Strasbourg, France
| | - Jérôme Terrand
- UMR-S INSERM 1109, University of Strasbourg, Strasbourg, France
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Steinfeld N, Ma CIJ, Maxfield FR. Signaling pathways regulating the extracellular digestion of lipoprotein aggregates by macrophages. Mol Biol Cell 2024; 35:ar5. [PMID: 37910189 PMCID: PMC10881170 DOI: 10.1091/mbc.e23-06-0239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/13/2023] [Accepted: 10/23/2023] [Indexed: 11/03/2023] Open
Abstract
The interaction between aggregated low-density lipoprotein (agLDL) and macrophages in arteries plays a major role in atherosclerosis. Macrophages digest agLDL and generate free cholesterol in an extracellular, acidic, hydrolytic compartment known as the lysosomal synapse. Macrophages form a tight seal around agLDL through actin polymerization and deliver lysosomal contents into this space in a process termed digestive exophagy. Our laboratory has identified TLR4 activation of MyD88/Syk as critical for digestive exophagy. Here we use pharmacological agents and siRNA knockdown to characterize signaling pathways downstream of Syk that are involved in digestive exophagy. Syk activates Bruton's tyrosine kinase (BTK) and phospholipase Cγ2 (PLCγ2). We show that PLCγ2 and to a lesser extent BTK regulate digestive exophagy. PLCγ2 cleaves PI(4,5)P2 into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). Soluble IP3 activates release of Ca2+ from the endoplasmic reticulum (ER). We demonstrate that Ca2+ release from the ER is upregulated by agLDL and plays a key role in digestive exophagy. Both DAG and Ca2+ activate protein kinase Cα (PKCα). We find that PKCα is an important regulator of digestive exophagy. These results expand our understanding of the mechanisms of digestive exophagy, which could be useful in developing therapeutic interventions to slow development of atherosclerosis.
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Affiliation(s)
- Noah Steinfeld
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065
| | - Cheng-I J. Ma
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065
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Galindo CL, Khan S, Zhang X, Yeh YS, Liu Z, Razani B. Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets. Expert Opin Ther Targets 2023; 27:1231-1245. [PMID: 38009300 PMCID: PMC10843715 DOI: 10.1080/14728222.2023.2288272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide. AREAS COVERED Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development. EXERT OPINION As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.
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Affiliation(s)
- Cristi L. Galindo
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
| | - Saifur Khan
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
| | - Xiangyu Zhang
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
| | - Yu-Sheng Yeh
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
| | - Ziyang Liu
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
| | - Babak Razani
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA
- Pittsburgh VA Medical Center, Pittsburgh, PA
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Korbelius M, Kuentzel KB, Bradić I, Vujić N, Kratky D. Recent insights into lysosomal acid lipase deficiency. Trends Mol Med 2023; 29:425-438. [PMID: 37028992 DOI: 10.1016/j.molmed.2023.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/14/2023] [Accepted: 03/14/2023] [Indexed: 04/09/2023]
Abstract
Lysosomal acid lipase (LAL) is the sole enzyme known to degrade neutral lipids in the lysosome. Mutations in the LAL-encoding LIPA gene lead to rare lysosomal lipid storage disorders with complete or partial absence of LAL activity. This review discusses the consequences of defective LAL-mediated lipid hydrolysis on cellular lipid homeostasis, epidemiology, and clinical presentation. Early detection of LAL deficiency (LAL-D) is essential for disease management and survival. LAL-D must be considered in patients with dyslipidemia and elevated aminotransferase concentrations of unknown etiology. Enzyme replacement therapy, sometimes in combination with hematopoietic stem cell transplantation (HSCT), is currently the only therapy for LAL-D. New technologies based on mRNA and viral vector gene transfer are recent efforts to provide other effective therapeutic strategies.
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Affiliation(s)
- Melanie Korbelius
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Katharina B Kuentzel
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Ivan Bradić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Nemanja Vujić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria.
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Maxfield FR, Steinfeld N, Ma CIJ. The formation and consequences of cholesterol-rich deposits in atherosclerotic lesions. Front Cardiovasc Med 2023; 10:1148304. [PMID: 36926046 PMCID: PMC10011067 DOI: 10.3389/fcvm.2023.1148304] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 02/13/2023] [Indexed: 03/06/2023] Open
Abstract
Cardiovascular diseases remain the leading cause of death throughout the world. Accumulation of lipoprotein-associated lipids and their interaction with macrophages are early steps in the development of atherosclerotic lesions. For decades, it has been known that aggregates of lipoproteins in the subendothelial space are found in early plaques, and these aggregates are tightly associated with extracellular matrix fibers. Additionally, most of the cholesterol in these subendothelial aggregates is unesterified, in contrast to the core of low-density lipoproteins (LDL), in which cholesteryl esters predominate. This suggests that the hydrolysis of cholesteryl esters occurs extracellularly. At the cellular level, macrophages in early plaques engage with the LDL and ingest large amounts of cholesterol, which is esterified and stored in lipid droplets. When excessive lipid droplets have accumulated, endoplasmic reticulum stress responses are activated, leading to cell death. The cholesterol-laden dead cells must be cleared by other macrophages. For many years, it was unclear how unesterified (free) cholesterol could be formed extracellularly in early lesions. Papers in the past decade have shown that macrophages form tightly sealed extracellular attachments to aggregates of LDL. These sealed regions become acidified, and lysosomal contents are secreted into these compartments. Lysosomal acid lipase hydrolyzes the cholesteryl esters, and the free cholesterol is transported into the macrophages. High concentrations of cholesterol can also lead to formation of crystals of cholesterol hydrate, and these crystals have been observed in atherosclerotic blood vessels. Characterization of this process may lead to novel therapies for the prevention and treatment of atherosclerosis.
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Macrophage-, Dendritic-, Smooth Muscle-, Endothelium-, and Stem Cells-Derived Foam Cells in Atherosclerosis. Int J Mol Sci 2022; 23:ijms232214154. [PMID: 36430636 PMCID: PMC9695208 DOI: 10.3390/ijms232214154] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 11/19/2022] Open
Abstract
Atherosclerosis is an inflammatory disease depending on the buildup, called plaque, of lipoproteins, cholesterol, extracellular matrix elements, and various types of immune and non-immune cells on the artery walls. Plaque development and growth lead to the narrowing of the blood vessel lumen, blocking blood flow, and eventually may lead to plaque burst and a blood clot. The prominent cellular components of atherosclerotic plaque are the foam cells, which, by trying to remove lipoprotein and cholesterol surplus, also participate in plaque development and rupture. Although the common knowledge is that the foam cells derive from macrophages, studies of the last decade clearly showed that macrophages are not the only cells able to form foam cells in atherosclerotic plaque. These findings give a new perspective on atherosclerotic plaque formation and composition and define new targets for anti-foam cell therapies for atherosclerosis prevention. This review gives a concise description of foam cells of different pedigrees and describes the main mechanisms participating in their formation and function.
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8
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Ashokcoomar S, Reedoy KS, Loots DT, Beukes D, van Reenen M, Pillay B, Pillay M. M. tuberculosis curli pili (MTP) facilitates a reduction of microbicidal activity of infected THP-1 macrophages during early stages of infection. Comp Immunol Microbiol Infect Dis 2022; 90-91:101907. [DOI: 10.1016/j.cimid.2022.101907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022]
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Zhang S, Liu Y, Cao Y, Zhang S, Sun J, Wang Y, Song S, Zhang H. Targeting the Microenvironment of Vulnerable Atherosclerotic Plaques: An Emerging Diagnosis and Therapy Strategy for Atherosclerosis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2110660. [PMID: 35238081 DOI: 10.1002/adma.202110660] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/10/2022] [Indexed: 06/14/2023]
Abstract
Atherosclerosis is considered one of the primary causes of cardiovascular diseases (CVDs). Unpredictable rupture of the vulnerable atherosclerotic plaques triggers adverse cardiovascular events such as acute myocardial syndrome and even sudden cardiac death. Therefore, assessing the vulnerability of atherosclerotic plaques and early intervention are of significance in reducing CVD mortality. Nanomedicine possesses tremendous advantages in achieving the integration of the diagnosis and therapy of atherosclerotic plaques because of its magnetic, optical, thermal, and catalytic properties. Based on the pathological characteristics of vulnerable plaques, stimuli-responsive nanoplatforms and surface-functionalized nanoagents are designed and have drawn great attention for accomplishing the precise imaging and treatment of vulnerable atherosclerotic plaques due to their superior properties, such as high bioavailability, lesion-targeting specificity, on-demand cargo release, and low off-target damage. Here, the characteristics of vulnerable plaques are generalized, and some targeted strategies for boosting the accuracy of plaque vulnerability evaluation by imaging and the efficacy of plaque stabilization therapy (including antioxidant therapy, macrophage depletion therapy, regulation of lipid metabolism therapy, anti-inflammation therapy, etc.) are systematically summarized. In addition, existing challenges and prospects in this field are discussed, and it is believed to provide new thinking for the diagnosis and treatment of CVDs in the near future.
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Affiliation(s)
- Shuai Zhang
- Department of Cardiovascular Center, The First Hospital of Jilin University, 71 Xinmin Street, Changchun, Jilin, 130021, China
| | - Yang Liu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yue Cao
- Department of Neurosurgery, The First Hospital of Jilin University, 71 Ximin Street, Changchun, Jilin, 130021, China
| | - Songtao Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
| | - Jian Sun
- Department of Cardiovascular Center, The First Hospital of Jilin University, 71 Xinmin Street, Changchun, Jilin, 130021, China
| | - Yinghui Wang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
| | - Shuyan Song
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Hongjie Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
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Xiang P, Blanchard V, Francis GA. Smooth Muscle Cell—Macrophage Interactions Leading to Foam Cell Formation in Atherosclerosis: Location, Location, Location. Front Physiol 2022; 13:921597. [PMID: 35795646 PMCID: PMC9251363 DOI: 10.3389/fphys.2022.921597] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Cholesterol-overloaded cells or “foam cells” in the artery wall are the biochemical hallmark of atherosclerosis, and are responsible for much of the growth, inflammation and susceptibility to rupture of atherosclerotic lesions. While it has previously been thought that macrophages are the main contributor to the foam cell population, recent evidence indicates arterial smooth muscle cells (SMCs) are the source of the majority of foam cells in both human and murine atherosclerosis. This review outlines the timeline, site of appearance and proximity of SMCs and macrophages with lipids in human and mouse atherosclerosis, and likely interactions between SMCs and macrophages that promote foam cell formation and removal by both cell types. An understanding of these SMC-macrophage interactions in foam cell formation and regression is expected to provide new therapeutic targets to reduce the burden of atherosclerosis for the prevention of coronary heart disease, stroke and peripheral vascular disease.
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11
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Susser LI, Rayner KJ. Through the layers: how macrophages drive atherosclerosis across the vessel wall. J Clin Invest 2022; 132:157011. [PMID: 35499077 PMCID: PMC9057606 DOI: 10.1172/jci157011] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Leah I. Susser
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Katey J. Rayner
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
- Centre for Infection, Immunity and Inflammation, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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12
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Microglial NF-κB drives tau spreading and toxicity in a mouse model of tauopathy. Nat Commun 2022; 13:1969. [PMID: 35413950 PMCID: PMC9005658 DOI: 10.1038/s41467-022-29552-6] [Citation(s) in RCA: 99] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/21/2022] [Indexed: 01/31/2023] Open
Abstract
Activation of microglia is a prominent pathological feature in tauopathies, including Alzheimer's disease. How microglia activation contributes to tau toxicity remains largely unknown. Here we show that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, activated by tau, drives microglial-mediated tau propagation and toxicity. Constitutive activation of microglial NF-κB exacerbated, while inactivation diminished, tau seeding and spreading in young PS19 mice. Inhibition of NF-κB activation enhanced the retention while reduced the release of internalized pathogenic tau fibrils from primary microglia and rescued microglial autophagy deficits. Inhibition of microglial NF-κB in aged PS19 mice rescued tau-mediated learning and memory deficits, restored overall transcriptomic changes while increasing neuronal tau inclusions. Single cell RNA-seq revealed that tau-associated disease states in microglia were diminished by NF-κB inactivation and further transformed by constitutive NF-κB activation. Our study establishes a role for microglial NF-κB signaling in mediating tau spreading and toxicity in tauopathy.
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Juhl AD, Wüstner D. Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging. Front Cell Dev Biol 2022; 10:834408. [PMID: 35300409 PMCID: PMC8920967 DOI: 10.3389/fcell.2022.834408] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/04/2022] [Indexed: 12/24/2022] Open
Abstract
Cholesterol is an essential molecule in cellular membranes, but too much cholesterol can be toxic. Therefore, mammalian cells have developed complex mechanisms to remove excess cholesterol. In this review article, we discuss what is known about such efflux pathways including a discussion of reverse cholesterol transport and formation of high-density lipoprotein, the function of ABC transporters and other sterol efflux proteins, and we highlight their role in human diseases. Attention is paid to the biophysical principles governing efflux of sterols from cells. We also discuss recent evidence for cholesterol efflux by the release of exosomes, microvesicles, and migrasomes. The role of the endo-lysosomal network, lipophagy, and selected lysosomal transporters, such as Niemann Pick type C proteins in cholesterol export from cells is elucidated. Since oxysterols are important regulators of cellular cholesterol efflux, their formation, trafficking, and secretion are described briefly. In addition to discussing results obtained with traditional biochemical methods, focus is on studies that use established and novel bioimaging approaches to obtain insight into cholesterol efflux pathways, including fluorescence and electron microscopy, atomic force microscopy, X-ray tomography as well as mass spectrometry imaging.
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Affiliation(s)
- Alice Dupont Juhl
- Department of Biochemistry and Molecular Biology, PhyLife, Physical Life Sciences, University of Southern Denmark, Odense, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, PhyLife, Physical Life Sciences, University of Southern Denmark, Odense, Denmark
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14
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Lorey MB, Öörni K, Kovanen PT. Modified Lipoproteins Induce Arterial Wall Inflammation During Atherogenesis. Front Cardiovasc Med 2022; 9:841545. [PMID: 35310965 PMCID: PMC8927694 DOI: 10.3389/fcvm.2022.841545] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 01/26/2022] [Indexed: 12/15/2022] Open
Abstract
Circulating apolipoprotein B-containing lipoproteins, notably the low-density lipoproteins, enter the inner layer of the arterial wall, the intima, where a fraction of them is retained and modified by proteases, lipases, and oxidizing agents and enzymes. The modified lipoproteins and various modification products, such as fatty acids, ceramides, lysophospholipids, and oxidized lipids induce inflammatory reactions in the macrophages and the covering endothelial cells, initiating an increased leukocyte diapedesis. Lipolysis of the lipoproteins also induces the formation of cholesterol crystals with strong proinflammatory properties. Modified and aggregated lipoproteins, cholesterol crystals, and lipoproteins isolated from human atherosclerotic lesions, all can activate macrophages and thereby induce the secretion of proinflammatory cytokines, chemokines, and enzymes. The extent of lipoprotein retention, modification, and aggregation have been shown to depend largely on differences in the composition of the circulating lipoprotein particles. These properties can be modified by pharmacological means, and thereby provide opportunities for clinical interventions regarding the prevention and treatment of atherosclerotic vascular diseases.
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Affiliation(s)
- Martina B. Lorey
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Katariina Öörni
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
- Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- *Correspondence: Katariina Öörni
| | - Petri T. Kovanen
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Helsinki, Finland
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15
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Martins Castanheira N, Spanhofer AK, Wiener S, Bobe S, Schillers H. Uptake of platelets by cancer cells and recycling of the platelet protein CD42a. J Thromb Haemost 2022; 20:170-181. [PMID: 34592045 DOI: 10.1111/jth.15543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND It is well accepted that the bidirectional crosstalk between platelets and cancer cells promotes tumorigenesis and metastasis. In an early step, cancer cells trigger platelet granule and extracellular vesicle release that is needed to facilitate cancer cell survival in circulation. OBJECTIVES To discover the early crosstalk of cancer cells and platelets. METHODS Cancer cells were incubated with freshly isolated and stained human platelets. Confocal laser scanning microscopy and flow cytometry was used to visualize and to quantify platelet uptake and the membrane presence of CD42 on cancer cells. Dyngo4a was used to test if platelet uptake is a dynamin-dependent process. RESULTS We found a dynamin-dependent uptake of platelets by cancer cells. This is followed by the recycling of the platelet-specific protein CD42a and its incorporation into cancer cells' plasma membrane, which is not a result of platelet RNA transfer by platelet-derived microparticles and exosomes. Time course of platelet uptake follows a sigmoid function revealing that 50% of the cancer cells are positive for platelets after approximately 38 min. Platelet uptake was observed for the tested cancerous cells (A549, MCF-7, and MV3) but not for the non-cancerous cell line 16HBE14o-. CONCLUSIONS Our results demonstrate that cancer cells hijack platelets by phagocytosis and recycling of platelet membrane proteins. The uptake of platelets has additional advantages for cancer cells: access to the entire and undiluted platelet proteome, transcriptome, and secretome. These novel findings will allow further mechanistic elucidation and thus help us gain deeper insights into platelet-assisted hematogenous metastasis.
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Affiliation(s)
| | - Anna K Spanhofer
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Sebastian Wiener
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Stefanie Bobe
- Institute of Physiology II, University of Muenster, Muenster, Germany
- Gerhard-Domagk-Institute of Pathology, University Hospital Muenster, Muenster, Germany
| | - Hermann Schillers
- Institute of Physiology II, University of Muenster, Muenster, Germany
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16
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Yoo Y, Choi E, Kim Y, Cha Y, Um E, Kim Y, Kim Y, Lee YS. Therapeutic potential of targeting cathepsin S in pulmonary fibrosis. Biomed Pharmacother 2021; 145:112245. [PMID: 34772578 DOI: 10.1016/j.biopha.2021.112245] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/18/2021] [Accepted: 09/22/2021] [Indexed: 11/16/2022] Open
Abstract
Cathepsin S (CTSS), a lysosomal protease, belongs to a family of cysteine cathepsin proteases that promote degradation of damaged proteins in the endolysosomal pathway. Aberrant CTSS expression and regulation are associated with the pathogenesis of several diseases, including lung diseases. CTSS overexpression causes a variety of pathological processes, including pulmonary fibrosis, with increased CTSS secretion and accelerated extracellular matrix remodeling. Compared to many other cysteine cathepsin family members, CTSS has unique features that it presents limited tissue expression and retains its enzymatic activity at a neutral pH, suggesting its decisive involvement in disease microenvironments. In this review, we investigated the role of CTSS in lung disease, exploring recent studies that have indicated that CTSS mediates fibrosis in unique ways, along with its structure, substrates, and distinct regulation. We also outlined examples of CTSS inhibitors in clinical and preclinical development and proposed CTSS as a potential therapeutic target for pulmonary fibrosis.
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Affiliation(s)
- YoungJo Yoo
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Eun Choi
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Yejin Kim
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Yunyoung Cha
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Eunhye Um
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Younghwa Kim
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Yunji Kim
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea
| | - Yun-Sil Lee
- Graduate School of Pharmaceutical Sciences and College of Pharmacy, Ewha Womans University, Seoul 120-720, Republic of Korea.
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17
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Grabner GF, Xie H, Schweiger M, Zechner R. Lipolysis: cellular mechanisms for lipid mobilization from fat stores. Nat Metab 2021; 3:1445-1465. [PMID: 34799702 DOI: 10.1038/s42255-021-00493-6] [Citation(s) in RCA: 185] [Impact Index Per Article: 61.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022]
Abstract
The perception that intracellular lipolysis is a straightforward process that releases fatty acids from fat stores in adipose tissue to generate energy has experienced major revisions over the last two decades. The discovery of new lipolytic enzymes and coregulators, the demonstration that lipophagy and lysosomal lipolysis contribute to the degradation of cellular lipid stores and the characterization of numerous factors and signalling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels have revolutionized our understanding of lipolysis. In this review, we focus on the mechanisms that facilitate intracellular fatty-acid mobilization, drawing on canonical and noncanonical enzymatic pathways. We summarize how intracellular lipolysis affects lipid-mediated signalling, metabolic regulation and energy homeostasis in multiple organs. Finally, we examine how these processes affect pathogenesis and how lipolysis may be targeted to potentially prevent or treat various diseases.
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Affiliation(s)
- Gernot F Grabner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Hao Xie
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Martina Schweiger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
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18
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Kuentzel KB, Bradić I, Akhmetshina A, Korbelius M, Rainer S, Kolb D, Gauster M, Vujić N, Kratky D. Defective Lysosomal Lipolysis Causes Prenatal Lipid Accumulation and Exacerbates Immediately after Birth. Int J Mol Sci 2021; 22:10416. [PMID: 34638755 PMCID: PMC8508985 DOI: 10.3390/ijms221910416] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 12/03/2022] Open
Abstract
Cholesterol and fatty acids are essential lipids that are critical for membrane biosynthesis and fetal organ development. Cholesteryl esters (CE) are degraded by hormone-sensitive lipase (HSL) in the cytosol and by lysosomal acid lipase (LAL) in the lysosome. Impaired LAL or HSL activity causes rare pathologies in humans, with HSL deficiency presenting less severe clinical manifestations. The infantile form of LAL deficiency, a lysosomal lipid storage disorder, leads to premature death. However, the importance of defective lysosomal CE degradation and its consequences during early life are incompletely understood. We therefore investigated how defective CE catabolism affects fetus and infant maturation using Lal and Hsl knockout (-/-) mouse models. This study demonstrates that defective lysosomal but not neutral lipolysis alters placental and fetal cholesterol homeostasis and exhibits an initial disease pathology already in utero as Lal-/- fetuses accumulate hepatic lysosomal lipids. Immediately after birth, LAL deficiency exacerbates with massive hepatic lysosomal lipid accumulation, which continues to worsen into young adulthood. Our data highlight the crucial role of LAL during early development, with the first weeks after birth being critical for aggravating LAL deficiency.
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Affiliation(s)
- Katharina B. Kuentzel
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Ivan Bradić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Alena Akhmetshina
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Melanie Korbelius
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Silvia Rainer
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Dagmar Kolb
- Gottfried Schatz Research Center, Cell Biology, Histology and Embryology, Medical University of Graz, 8010 Graz, Austria; (D.K.); (M.G.)
- Core Facility Ultrastructural Analysis, Medical University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Martin Gauster
- Gottfried Schatz Research Center, Cell Biology, Histology and Embryology, Medical University of Graz, 8010 Graz, Austria; (D.K.); (M.G.)
| | - Nemanja Vujić
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
| | - Dagmar Kratky
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; (K.B.K.); (I.B.); (A.A.); (M.K.); (S.R.); (N.V.)
- BioTechMed-Graz, 8010 Graz, Austria
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19
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Ruuth M, Lahelma M, Luukkonen PK, Lorey MB, Qadri S, Sädevirta S, Hyötyläinen T, Kovanen PT, Hodson L, Yki-Järvinen H, Öörni K. Overfeeding Saturated Fat Increases LDL (Low-Density Lipoprotein) Aggregation Susceptibility While Overfeeding Unsaturated Fat Decreases Proteoglycan-Binding of Lipoproteins. Arterioscler Thromb Vasc Biol 2021; 41:2823-2836. [PMID: 34470478 PMCID: PMC8545249 DOI: 10.1161/atvbaha.120.315766] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Supplemental Digital Content is available in the text. Objective: We recently showed that measurement of the susceptibility of LDL (low-density lipoprotein) to aggregation is an independent predictor of cardiovascular events. We now wished to compare effects of overfeeding different dietary macronutrients on LDL aggregation, proteoglycan-binding of plasma lipoproteins, and on the concentration of oxidized LDL in plasma, 3 in vitro parameters consistent with increased atherogenicity. Approach and Results: The participants (36 subjects; age, 48±10 years; body mass index, 30.9±6.2 kg/m2) were randomized to consume an extra 1000 kcal/day of either unsaturated fat, saturated fat, or simple sugars (CARB) for 3 weeks. We measured plasma proatherogenic properties (susceptibility of LDL to aggregation, proteoglycan-binding, oxidized LDL) and concentrations and composition of plasma lipoproteins using nuclear magnetic resonance spectroscopy, and in LDL using liquid chromatography mass spectrometry, before and after the overfeeding diets. LDL aggregation increased in the saturated fat but not the other groups. This change was associated with increased sphingolipid and saturated triacylglycerols in LDL and in plasma and reduction of clusterin on LDL particles. Proteoglycan binding of plasma lipoproteins decreased in the unsaturated fat group relative to the baseline diet. Lipoprotein properties remained unchanged in the CARB group. Conclusions: The type of fat during 3 weeks of overfeeding is an important determinant of the characteristics and functional properties of plasma lipoproteins in humans. Registration: URL: http://www.clinicaltrials.gov; Unique identifier NCT02133144.
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Affiliation(s)
- Maija Ruuth
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Haartmaninkatu, Helsinki, Finland (M.R., M.B.L., P.T.K., K.Ö.).,Research Programs Unit, Faculty of Medicine, University of Helsinki, Finland (M.R.)
| | - Mari Lahelma
- Minerva Foundation Institute for Medical Research, Helsinki, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.).,Department of Medicine, University of Helsinki and Helsinki University Hospital, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.)
| | - Panu K Luukkonen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.).,Department of Medicine, University of Helsinki and Helsinki University Hospital, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.)
| | - Martina B Lorey
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Haartmaninkatu, Helsinki, Finland (M.R., M.B.L., P.T.K., K.Ö.)
| | - Sami Qadri
- Minerva Foundation Institute for Medical Research, Helsinki, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.).,Department of Medicine, University of Helsinki and Helsinki University Hospital, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.)
| | - Sanja Sädevirta
- Minerva Foundation Institute for Medical Research, Helsinki, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.).,Department of Medicine, University of Helsinki and Helsinki University Hospital, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.)
| | - Tuulia Hyötyläinen
- School of Science and Technology, Örebro University, Örebro, Sweden (T.H.)
| | - Petri T Kovanen
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Haartmaninkatu, Helsinki, Finland (M.R., M.B.L., P.T.K., K.Ö.)
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, and National Institute for Health Research Oxford Biomedical Research Centre, Oxford University Hospital Trusts, United Kingdom (L.H.)
| | - Hannele Yki-Järvinen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.).,Department of Medicine, University of Helsinki and Helsinki University Hospital, Finland (M.L., P.K.L., S.Q., S.S., H.Y.-J.)
| | - Katariina Öörni
- Atherosclerosis Research Laboratory, Wihuri Research Institute, Haartmaninkatu, Helsinki, Finland (M.R., M.B.L., P.T.K., K.Ö.)
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20
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Horn CL, Morales AL, Savard C, Farrell GC, Ioannou GN. Role of Cholesterol-Associated Steatohepatitis in the Development of NASH. Hepatol Commun 2021; 6:12-35. [PMID: 34558856 PMCID: PMC8710790 DOI: 10.1002/hep4.1801] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 07/08/2021] [Accepted: 07/14/2021] [Indexed: 12/11/2022] Open
Abstract
The rising prevalence of nonalcoholic fatty liver disease (NAFLD) and NAFLD-related cirrhosis in the United States and globally highlights the need to better understand the mechanisms causing progression of hepatic steatosis to fibrosing steatohepatitis and cirrhosis in a small proportion of patients with NAFLD. Accumulating evidence suggests that lipotoxicity mediated by hepatic free cholesterol (FC) overload is a mechanistic driver for necroinflammation and fibrosis, characteristic of nonalcoholic steatohepatitis (NASH), in many animal models and also in some patients with NASH. Diet, lifestyle, obesity, key genetic polymorphisms, and hyperinsulinemia secondary to insulin resistance are pivotal drivers leading to aberrant cholesterol signaling, which leads to accumulation of FC within hepatocytes. FC overload in hepatocytes can lead to ER stress, mitochondrial dysfunction, development of toxic oxysterols, and cholesterol crystallization in lipid droplets, which in turn lead to hepatocyte apoptosis, necrosis, or pyroptosis. Activation of Kupffer cells and hepatic stellate cells by hepatocyte signaling and cholesterol loading contributes to this inflammation and leads to hepatic fibrosis. Cholesterol accumulation in hepatocytes can be readily prevented or reversed by statins. Observational studies suggest that use of statins in NASH not only decreases the substantially increased cardiovascular risk, but may ameliorate liver pathology. Conclusion: Hepatic FC loading may result in cholesterol-associated steatohepatitis and play an important role in the development and progression of NASH. Statins appear to provide significant benefit in preventing progression to NASH and NASH-cirrhosis. Randomized controlled trials are needed to demonstrate whether statins or statin/ezetimibe combination can effectively reverse steatohepatitis and liver fibrosis in patients with NASH.
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Affiliation(s)
- Christian L Horn
- Division of Gastroenterology and Hepatology, Department of Medicine, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
| | - Amilcar L Morales
- Division of Gastroenterology and Hepatology, Department of Medicine, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA.,Division of Gastroenterology, Department of Medicine, University of Washington, Seattle, WA, USA.,Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
| | - Geoffrey C Farrell
- Liver Research Group, ANU Medical School, Australian National University at the Canberra Hospital, Garran, ACT, Australia
| | - George N Ioannou
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA.,Division of Gastroenterology, Department of Medicine, University of Washington, Seattle, WA, USA.,Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
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21
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Scott J, Deng Q, Vendrell M. Near-Infrared Fluorescent Probes for the Detection of Cancer-Associated Proteases. ACS Chem Biol 2021; 16:1304-1317. [PMID: 34315210 PMCID: PMC8383269 DOI: 10.1021/acschembio.1c00223] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/14/2021] [Indexed: 12/11/2022]
Abstract
Proteases are enzymes capable of catalyzing protein breakdown, which is critical across many biological processes. There are several families of proteases, each of which perform key functions through the degradation of specific proteins. As our understanding of cancer improves, it has been demonstrated that several proteases can be overactivated during the progression of cancer and contribute to malignancy. Optical imaging systems that employ near-infrared (NIR) fluorescent probes to detect protease activity offer clinical promise, both for early detection of cancer as well as for the assessment of personalized therapy. In this Review, we review the design of NIR probes and their successful application for the detection of different cancer-associated proteases.
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Affiliation(s)
- Jamie
I. Scott
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4TJ Edinburgh, United Kingdom
| | - Qinyi Deng
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4TJ Edinburgh, United Kingdom
| | - Marc Vendrell
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4TJ Edinburgh, United Kingdom
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22
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Cabodevilla AG, Tang S, Lee S, Mullick AE, Aleman JO, Hussain MM, Sessa WC, Abumrad NA, Goldberg IJ. Eruptive xanthoma model reveals endothelial cells internalize and metabolize chylomicrons, leading to extravascular triglyceride accumulation. J Clin Invest 2021; 131:e145800. [PMID: 34128469 PMCID: PMC8203467 DOI: 10.1172/jci145800] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Although tissue uptake of fatty acids from chylomicrons is primarily via lipoprotein lipase (LpL) hydrolysis of triglycerides (TGs), studies of patients with genetic LpL deficiency suggest additional pathways deliver dietary lipids to tissues. Despite an intact endothelial cell (EC) barrier, hyperchylomicronemic patients accumulate chylomicron-derived lipids within skin macrophages, leading to the clinical finding eruptive xanthomas. We explored whether an LpL-independent pathway exists for transfer of circulating lipids across the EC barrier. We found that LpL-deficient mice had a marked increase in aortic EC lipid droplets before and after a fat gavage. Cultured ECs internalized chylomicrons, which were hydrolyzed within lysosomes. The products of this hydrolysis fueled lipid droplet biogenesis in ECs and triggered lipid accumulation in cocultured macrophages. EC chylomicron uptake was inhibited by competition with HDL and knockdown of the scavenger receptor-BI (SR-BI). In vivo, SR-BI knockdown reduced TG accumulation in aortic ECs and skin macrophages of LpL-deficient mice. Thus, ECs internalize chylomicrons, metabolize them in lysosomes, and either store or release their lipids. This latter process may allow accumulation of TGs within skin macrophages and illustrates a pathway that might be responsible for creation of eruptive xanthomas.
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Affiliation(s)
- Ainara G Cabodevilla
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, New York, USA
| | - Songtao Tang
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, New York, USA
| | - Sungwoon Lee
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | - Jose O Aleman
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, New York, USA
| | - M Mahmood Hussain
- Diabetes and Obesity Center, NYU-Long Island School of Medicine, Mineola, New York, USA
| | - William C Sessa
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Nada A Abumrad
- Nutritional Sciences, Department of Medicine and Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Ira J Goldberg
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, New York, USA
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23
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Öörni K, Kovanen PT. Aggregation Susceptibility of Low-Density Lipoproteins-A Novel Modifiable Biomarker of Cardiovascular Risk. J Clin Med 2021; 10:1769. [PMID: 33921661 PMCID: PMC8074066 DOI: 10.3390/jcm10081769] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/31/2021] [Accepted: 04/13/2021] [Indexed: 01/07/2023] Open
Abstract
Circulating low-density lipoprotein (LDL) particles enter the arterial intima where they bind to the extracellular matrix and become modified by lipases, proteases, and oxidizing enzymes and agents. The modified LDL particles aggregate and fuse into larger matrix-bound lipid droplets and, upon generation of unesterified cholesterol, cholesterol crystals are also formed. Uptake of the aggregated/fused particles and cholesterol crystals by macrophages and smooth muscle cells induces their inflammatory activation and conversion into foam cells. In this review, we summarize the causes and consequences of LDL aggregation and describe the development and applications of an assay capable of determining the susceptibility of isolated LDL particles to aggregate when exposed to human recombinant sphingomyelinase enzyme ex vivo. Significant person-to-person differences in the aggregation susceptibility of LDL particles were observed, and such individual differences largely depended on particle lipid composition. The presence of aggregation-prone LDL in the circulation predicted future cardiovascular events in patients with atherosclerotic cardiovascular disease. We also discuss means capable of reducing LDL particles' aggregation susceptibility that could potentially inhibit LDL aggregation in the arterial wall. Whether reductions in LDL aggregation susceptibility are associated with attenuated atherogenesis and a reduced risk of atherosclerotic cardiovascular diseases remains to be studied.
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Affiliation(s)
- Katariina Öörni
- Wihuri Research Institute, 00290 Helsinki, Finland;
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
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24
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Lee W, Yudhistira T, Youn W, Han S, Halle MB, Choi JH, Kim Y, Choi IS, Churchill DG. Inexpensive water soluble methyl methacrylate-functionalized hydroxyphthalimide: variations of the mycophenolic acid core for selective live cell imaging of free cysteine. Analyst 2021; 146:2212-2220. [PMID: 33595018 DOI: 10.1039/d0an02185g] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Evident from numerous studies, cysteine plays a crucial role in cellular function. Reactions with analyte also enables for molecular recognition to adhere to molecular therapeutic potential; integration between synthetic probes therefore allows for a potentially deep therapy-related interogation of biological systems (theranostics). The development of molecular cysteine probes with extremely accurate detection is still a key challenge for the field. The development of water-soluble organic molecular fluorescent probes able to efficiently distinguish common biothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) by chemical recognition means i.e. by (binding, cleavage) in biological systems is a greatly sought research challenge due to the similarity of the small sulfhydryl-containing species. Herein, we have developed a water-soluble and highly cell viable fluorescent organic molecule (log P = 0.82) for the selective detection of cysteine. The probe (Myco-Cys) shows a "turn-on" response with the cleavage ester linkage of the methacrylate as cysteine is encountered in solution. The probe shows strong fluorescence enhancement (16.5-fold) when treated with Cys (1 equiv., 10 μM) compared to closely related species such as amino acids, including HCy/GSH, and the limit of detection was determined as 45.0 nM. DFT calculations helped confirm the photomechanism of Myco-Cys. Furthermore, the sensing ability of the probe was demonstrated by living cell assays through the use of confocal fluorescence microscopy. Myco-Cys could selectively detect cysteine among biothiols. Myco-Cys was able to monitor the cysteine level, apart from the oxidative stress present in the form of H2O2 in A549 cells.
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Affiliation(s)
- Woohyun Lee
- Department of Chemistry, Molecular Logic Gate Laboratory, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea.
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25
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Acidic extracellular pH promotes accumulation of free cholesterol in human monocyte-derived macrophages via inhibition of ACAT1 activity. Atherosclerosis 2020; 312:1-7. [PMID: 32942042 DOI: 10.1016/j.atherosclerosis.2020.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS In focal areas of advanced human atherosclerotic lesions, the intimal fluid is acidic. An acidic medium impairs the ABCA1-mediated cholesterol efflux from macrophages, so tending to increase their content of free cholesterol, which is then available for esterification by the macrophage enzyme ACAT1. Here we investigated whether low extracellular pH would affect the activity of ACAT1. METHODS - Human monocyte-derived macrophages were first incubated with acetyl-LDL at neutral and acidic conditions (pH 7.5, 6.5, and 5.5) to generate foam cells, and then the foam cells were incubated with [3H]oleate-BSA complexes, and the formation of [3H]oleate-labeled cholesteryl esters was measured. ACAT1 activity was also measured in cell-free macrophage extracts. RESULTS - In acidic media, ACAT1-dependent cholesteryl [3H]oleate generation became compromised in the developing foam cells and their content of free cholesterol increased. In line with this finding, ACAT1 activity in the soluble cell-free fraction derived from macrophage foam cells peaked at pH 7, and gradually decreased under acidic pH with a rapid drop below pH 6.5. Incubation of macrophages under progressively more acidic conditions (until pH 5.5) lowered the cytosolic pH of macrophages (down to pH 6.0). Such intracellular acidification did not affect macrophage gene expression of ACAT1 or the neutral CEH. CONCLUSIONS Exposure of human macrophage foam cells to acidic conditions lowers their intracellular pH with simultaneous decrease in ACAT1 activity. This reduces cholesterol esterification and thus leads to accumulation of potentially toxic levels of free cholesterol, a contributing factor to macrophage foam cell death.
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26
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Pathak A, Singh SK, Thewke DP, Agrawal A. Conformationally Altered C-Reactive Protein Capable of Binding to Atherogenic Lipoproteins Reduces Atherosclerosis. Front Immunol 2020; 11:1780. [PMID: 32849641 PMCID: PMC7431523 DOI: 10.3389/fimmu.2020.01780] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/03/2020] [Indexed: 12/27/2022] Open
Abstract
The aim of this study was to test the hypothesis that C-reactive protein (CRP) protects against the development of atherosclerosis and that a conformational alteration of wild-type CRP is necessary for CRP to do so. Atherosclerosis is an inflammatory cardiovascular disease and CRP is a plasma protein produced by the liver in inflammatory states. The co-localization of CRP and low-density lipoproteins (LDL) at atherosclerotic lesions suggests a possible role of CRP in atherosclerosis. CRP binds to phosphocholine-containing molecules but does not interact with LDL unless the phosphocholine groups in LDL are exposed. However, CRP can bind to LDL, without the exposure of phosphocholine groups, if the native conformation of CRP is altered. Previously, we reported a CRP mutant, F66A/T76Y/E81A, generated by site-directed mutagenesis, that did not bind to phosphocholine. Unexpectedly, this mutant CRP, without any more conformational alteration, was found to bind to atherogenic LDL. We hypothesized that this CRP mutant, unlike wild-type CRP, could be anti-atherosclerotic and, accordingly, the effects of mutant CRP on atherosclerosis in atherosclerosis-prone LDL receptor-deficient mice were evaluated. Administration of mutant CRP into mice every other day for a few weeks slowed the progression of atherosclerosis. The size of atherosclerotic lesions in the aorta of mice treated with mutant CRP for 9 weeks was ~40% smaller than the lesions in the aorta of untreated mice. Thus, mutant CRP conferred protection against atherosclerosis, providing a proof of concept that a local inflammation-induced structural change in wild-type CRP is a prerequisite for CRP to control the development of atherosclerosis.
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Affiliation(s)
- Asmita Pathak
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Sanjay K Singh
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Douglas P Thewke
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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27
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Atias Z, Pederson JM, Mishra HK, Greenberger S. The effect of natural matrix biopolymer membrane on hard-to-heal venous leg ulcers: a pilot randomised clinical trial. J Wound Care 2020; 29:295-302. [PMID: 32421486 DOI: 10.12968/jowc.2020.29.5.295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the therapeutic effects of natural matrix biopolymer membrane (NMBM) in the treatment of venous leg ulcers (VLUs). METHOD Patients exhibiting one or more VLU were assigned to a test group receiving NMBM or to a control group receiving conventional treatment. Patients exhibiting venous insufficiency-related ulcers within 0.1-170cm2 were included. Efficacy was assessed based on ulcer size and visual analogue scale (VAS) pain scores at baseline and at weeks one, two and four. Ulcer size and pain were compared between groups using a two-way ANOVA. RESULTS In this study, 25 patients with 32 VLUs (NMBM group: 14 patients with 17 ulcers; control group: 11 patients with 15 ulcers) were included in the final analysis. At four weeks after baseline measurements, the mean percentage change in VLU area of patients in the NMBM group was 61.6% (95% CI: 40.3-82.9) compared with 84.1% (95% CI: 56.5-111.7) for control group patients. Additionally, the mean percentage change in VLU volume of NMBM group patients was 51.2% (95% CI: 31.8-70.6) compared with 84.0% (95% CI: 57.0-121.0) for control group patients. The NMBM group patients exhibited a mean decrease of 0.38 (95% CI: -0.85-1.61) in VAS pain score over four weeks, compared with a mean decrease of 0.13 (95% CI: -1.32-1.58) for control group patients. No significant differences in VLU area (p=0.210), volume (p=0.122) or VAS pain score (p=0.460) were shown between groups. CONCLUSION NMBM was found to be as effective and safe as the control group treatments. This pilot study suggests NMBM can be used safely to promote ulcer healing.
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Affiliation(s)
- Ziva Atias
- Department of Dermatology, Sheba Medical Center, Ramat Gan, Israel
| | - John M Pederson
- University of Minnesota: Twin Cities, Minneapolis, Minnesota, US
| | - Hemant K Mishra
- University of Minnesota: Twin Cities, Minneapolis, Minnesota, US
| | - Shoshana Greenberger
- Department of Dermatology, Sheba Medical Center, Ramat Gan, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Shao Q, Yang M, Liang C, Ma L, Zhang W, Jiang Z, Luo J, Lee JK, Liang C, Chen JF. C9orf72 and smcr8 mutant mice reveal MTORC1 activation due to impaired lysosomal degradation and exocytosis. Autophagy 2019; 16:1635-1650. [PMID: 31847700 DOI: 10.1080/15548627.2019.1703353] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
How lysosome and MTORC1 signaling interact remains elusive in terminally differentiated cells. A G4C2 repeat expansion in C9orf72 is the most common cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9ALS-FTD). We previously identified a C9orf72-SMCR8-containing complex. Here we found that c9orf72 and smcr8 double-knockout (dKO) mice exhibit similar but more severe immune defects than the individual knockouts. In c9orf72 or smcr8 mutant macrophages, lysosomal degradation and exocytosis were impaired due to the disruption of autolysosome acidification. As a result of impaired lysosomal degradation, MTOR protein was aberrantly increased, resulting in MTORC1 signaling overactivation. Inhibition of hyperactive MTORC1 partially rescued macrophage dysfunction, splenomegaly and lymphadenopathy in c9orf72 or smcr8 mutant mice. Pharmacological inhibition of lysosomal degradation upregulated MTOR protein and MTORC1 signaling in differentiated wild-type macrophages, which resemble phenotypes in KO mice. In contrast, C9orf72 or Smcr8 depletion in proliferating macrophages decreased MTORC1 signaling. Our studies causatively link C9orf72-SMCR8's cellular functions in lysosomal degradation, exocytosis, and MTORC1 signaling with their organism-level immune regulation, suggesting cell state (proliferation vs. differentiation)-dependent regulation of MTOR signaling via lysosomes.Abbreviations: ALS: amyotrophic lateral sclerosis; ATG13: autophagy related 13; BMDMs: bone marrow-derived macrophages; BafA1: bafilomycin A1; C9orf72: C9orf72, member of C9orf72-SMCR8 complex; CD68: CD68 antigen; ConA: concanamycin A; dKO: double knockout; DENN: differentially expressed in normal and neoplastic cells; FTD: frontotemporal dementia; GEF: guanine nucleotide exchange factor; IFNB1: interferon beta 1, fibroblast; IFNG: interferon gamma; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; iPSCs: induced pluripotent stem cells; LAMP1: lysosomal-associated membrane protein 1; LPOs: LAMP1-positive organelles; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; LPS: lipopolysaccharide; MTORC1: mechanistic target of rapamycin kinase complex 1; MEFs: mouse embryonic fibroblasts; MNs: motor neurons; NOS2/iNOS: nitric oxide synthase 2, inducible; RAN: repeat-associated non-AUG; RB1CC1/FIP200: RB1-inducible coiled-coil 1; RPS6/S6: ribosomal protein S6; RPS6KB1/S6K1: ribosomal protein S6 kinase, polypeptide 1; SMCR8: Smith-Magenis syndrome chromosome region, candidate 8; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TNF: tumor necrosis factor; TSC1: TSC complex subunit 1; ULK1: unc-51 like kinase 1; v-ATPase: vacuolar-type H⁺-translocating ATPase.
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Affiliation(s)
- Qiang Shao
- Center for Craniofacial Molecular Biology, University of Southern California , Los Angeles, CA, USA
| | - Mei Yang
- Center for Craniofacial Molecular Biology, University of Southern California , Los Angeles, CA, USA.,Center for Life Sciences, School of Life Sciences, Yunnan University , Kunming, P.R. China
| | - Chen Liang
- Department of Cellular Biology, University of Georgia , Athens, GA, USA
| | - Li Ma
- Center for Craniofacial Molecular Biology, University of Southern California , Los Angeles, CA, USA
| | - Wei Zhang
- Center for Craniofacial Molecular Biology, University of Southern California , Los Angeles, CA, USA
| | - Zhiwen Jiang
- Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Institute of Aging Research, Guangdong Medical University , Dongguan, Guangdong, P.R. China
| | - Jun Luo
- Division of VIP Center, Stomatological Hospital of Chongqing Medical University , Chongqing, P.R. China
| | - Jae-Kyung Lee
- Department of Physiology and Pharmacology, University of Georgia , Athens, GA, USA
| | - Chengyu Liang
- Department of Molecular Microbiology and Immunology, Keck School of Medicine of the University of Southern California , Los Angeles, CA, USA
| | - Jian-Fu Chen
- Center for Craniofacial Molecular Biology, University of Southern California , Los Angeles, CA, USA
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Singh RK, Haka AS, Bhardwaj P, Zha X, Maxfield FR. Dynamic Actin Reorganization and Vav/Cdc42-Dependent Actin Polymerization Promote Macrophage Aggregated LDL (Low-Density Lipoprotein) Uptake and Catabolism. Arterioscler Thromb Vasc Biol 2019; 39:137-149. [PMID: 30580573 DOI: 10.1161/atvbaha.118.312087] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Objective- During atherosclerosis, LDLs (low-density lipoproteins) accumulate in the arteries, where they become modified, aggregated, and retained. Such deposits of aggregated LDL (agLDL) can be recognized by macrophages, which attempt to digest and clear them. AgLDL catabolism promotes internalization of cholesterol and foam cell formation, which leads to the progression of atherosclerosis. Therapeutic blockade of this process may delay disease progression. When macrophages interact with agLDL in vitro, they form a novel extracellular, hydrolytic compartment-the lysosomal synapse (LS)-aided by local actin polymerization to digest agLDL. Here, we investigated the specific regulators involved in actin polymerization during the formation of the LS. Approach and Results- We demonstrate in vivo that atherosclerotic plaque macrophages contacting agLDL deposits polymerize actin and form a compartment strikingly similar to those made in vitro. Live cell imaging revealed that macrophage cortical F-actin depolymerization is required for actin polymerization to support the formation of the LS. This depolymerization is cofilin-1 dependent. Using siRNA-mediated silencing, pharmacological inhibition, genetic knockout, and stable overexpression, we elucidate key roles for Cdc42 Rho GTPase and GEF (guanine nucleotide exchange factor) Vav in promoting actin polymerization during the formation of the LS and exclude a role for Rac1. Conclusions- These results highlight critical roles for dynamic macrophage F-actin rearrangement and polymerization via cofilin-1, Vav, and Cdc42 in LS formation, catabolism of agLDL, and foam cell formation. These proteins might represent therapeutic targets to treat atherosclerotic disease.
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Affiliation(s)
- Rajesh K Singh
- From the Department of Biochemistry, Weill Cornell Medical College, New York (R.K.S., A.S.H., P.B., F.R.M.)
| | - Abigail S Haka
- From the Department of Biochemistry, Weill Cornell Medical College, New York (R.K.S., A.S.H., P.B., F.R.M.)
| | - Priya Bhardwaj
- From the Department of Biochemistry, Weill Cornell Medical College, New York (R.K.S., A.S.H., P.B., F.R.M.)
| | - Xiaohui Zha
- Department of Biochemistry, Microbiology, and Immunology (X.Z.), University of Ottawa, ON, Canada.,Department of Medicine (X.Z.), University of Ottawa, ON, Canada.,Chronic Disease Program, Ottawa Hospital Research Institute, ON, Canada (X.Z.)
| | - Frederick R Maxfield
- From the Department of Biochemistry, Weill Cornell Medical College, New York (R.K.S., A.S.H., P.B., F.R.M.)
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30
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Maxfield FR, Barbosa-Lorenzi VC, Singh RK. Digestive exophagy: Phagocyte digestion of objects too large for phagocytosis. Traffic 2019; 21:6-12. [PMID: 31664749 DOI: 10.1111/tra.12712] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/18/2019] [Accepted: 10/26/2019] [Indexed: 12/29/2022]
Abstract
Mammalian phagocytes carry out several essential functions, including killing and digesting infectious organisms, clearing denatured proteins, removing dead cells and removing several types of debris from the extracellular space. Many of these functions involve phagocytosis, the engulfment of a target in a specialized endocytic process and then fusion of the new phagosome with lysosomes. Phagocytes such as macrophages can phagocytose targets that are several micrometers in diameter (eg, dead cells), but in some cases they encounter much larger objects. We have studied two such examples in some detail: large deposits of lipoproteins such as those in the wall of blood vessels associated with atherosclerosis, and dead adipocytes, which are dozens of micrometers in diameter. We describe a process, which we call digestive exophagy, in which macrophages create a tight seal in contact with the target, acidify the sealed zone and secrete lysosomal contents into the contact zone. By this process, hydrolysis by lysosomal enzymes occurs in a compartment that is outside the cell. We compare this process to the well characterized digestion of bone by osteoclasts, and we point out key similarities and differences.
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Affiliation(s)
| | | | - Rajesh K Singh
- Department of Biochemistry, Weill Cornell Medicine, New York, New York
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31
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Singh RK, Lund FW, Haka AS, Maxfield FR. High-density lipoprotein or cyclodextrin extraction of cholesterol from aggregated LDL reduces foam cell formation. J Cell Sci 2019; 132:jcs.237271. [PMID: 31719160 DOI: 10.1242/jcs.237271] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 11/05/2019] [Indexed: 01/29/2023] Open
Abstract
Low-density lipoprotein (LDL) deposition, aggregation and retention in the endothelial sub-intima are critical initiating events during atherosclerosis. Macrophages digest aggregated LDL (agLDL) through a process called exophagy. High-density lipoprotein (HDL) plays an atheroprotective role, but studies attempting to exploit it therapeutically have been unsuccessful, highlighting gaps in our current understanding of HDL function. Here, we characterized the role of HDL during exophagy of agLDL. We find that atherosclerotic plaque macrophages contact agLDL and form an extracellular digestive compartment similar to that observed in vitro During macrophage catabolism of agLDL in vitro, levels of free cholesterol in the agLDL are increased. HDL can extract free cholesterol directly from this agLDL and inhibit macrophage foam cell formation. Cholesterol-balanced hydroxypropyl-β-cyclodextrin similarly reduced macrophage cholesterol uptake and foam cell formation. Finally, we show that HDL can directly extract free cholesterol, but not cholesterol esters, from agLDL in the absence of cells. Together, these results suggest that the actions of HDL can directly extract free cholesterol from agLDL during catabolism, and provide a new context in which to view the complex relationship between HDL and atherosclerosis.
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Affiliation(s)
- Rajesh K Singh
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Frederik W Lund
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Abigail S Haka
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
| | - Frederick R Maxfield
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA
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Salazar ML, Jiménez JM, Villar J, Rivera M, Báez M, Manubens A, Becker MI. N-Glycosylation of mollusk hemocyanins contributes to their structural stability and immunomodulatory properties in mammals. J Biol Chem 2019; 294:19546-19564. [PMID: 31719148 PMCID: PMC6926458 DOI: 10.1074/jbc.ra119.009525] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
Hemocyanins are widely used as carriers, adjuvants, and nonspecific immunostimulants in cancer because they promote Th1 immunity in mammals. Hemocyanins also interact with glycan-recognizing innate immune receptors on antigen-presenting cells, such as the C-type lectin immune receptors mannose receptor (MR), macrophage galactose lectin (MGL), and the Toll-like receptors (TLRs), stimulating proinflammatory cytokine secretion. However, the role of N-linked oligosaccharides on the structural and immunological properties of hemocyanin is unclear. Mollusk hemocyanins, such as Concholepas concholepas (CCH), Fissurella latimarginata (FLH), and Megathura crenulata (KLH), are oligomeric glycoproteins with complex dodecameric quaternary structures and heterogeneous glycosylation patterns, primarily consisting of mannose-rich N-glycans. Here, we report that enzyme-catalyzed N-deglycosylation of CCH, FLH, and KLH disrupts their quaternary structure and impairs their immunogenic effects. Biochemical analyses revealed that the deglycosylation does not change hemocyanin secondary structure but alters their refolding mechanism and dodecameric structure. Immunochemical analyses indicated decreased binding of N-deglycosylated hemocyanins to the MR and MGL receptors and TLR4 and reduced endocytosis concomitant with an impaired production of tumor necrosis factor α, and interleukins 6 and 12 (IL-6 and IL-12p40, respectively) in macrophages. Evaluating the function of N-deglycosylated hemocyanins in the humoral immune response and their nonspecific antitumor effects in the B16F10 melanoma model, we found that compared with native hemocyanins N-deglycosylated hemocyanins elicited reduced antibody titers, as well as partially diminished antitumor effects and altered carrier activities. In conclusion, the glycan content of hemocyanins is, among other structural characteristics, critically required for their immunological activities and should be considered in biomedical applications.
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Affiliation(s)
- Michelle L Salazar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - José M Jiménez
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - Javiera Villar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - Maira Rivera
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380494, Chile
| | - Mauricio Báez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380494, Chile
| | - Augusto Manubens
- Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750269, Chile
| | - María Inés Becker
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile .,Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750269, Chile
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Boyles MSP, Poland CA, Raftis J, Duffin R. Assessment of the physicochemical properties of chrysotile-containing brake debris pertaining to toxicity. Inhal Toxicol 2019; 31:325-342. [DOI: 10.1080/08958378.2019.1683103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Craig A. Poland
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Jennifer Raftis
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Rodger Duffin
- Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Concept Life Sciences, 2 James Lindsay Place Dundee Technopole Dundee, Dundee, Scotland
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Ruuth M, Janssen LG, Äikäs L, Tigistu-Sahle F, Nahon KJ, Ritvos O, Ruhanen H, Käkelä R, Boon MR, Öörni K, Rensen PC. LDL aggregation susceptibility is higher in healthy South Asian compared with white Caucasian men. J Clin Lipidol 2019; 13:910-919.e2. [DOI: 10.1016/j.jacl.2019.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/20/2019] [Accepted: 09/22/2019] [Indexed: 12/13/2022]
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Singh RK, Haka AS, Asmal A, Barbosa-Lorenzi VC, Grosheva I, Chin HF, Xiong Y, Hla T, Maxfield FR. TLR4 (Toll-Like Receptor 4)-Dependent Signaling Drives Extracellular Catabolism of LDL (Low-Density Lipoprotein) Aggregates. Arterioscler Thromb Vasc Biol 2019; 40:86-102. [PMID: 31597445 DOI: 10.1161/atvbaha.119.313200] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Aggregation and modification of LDLs (low-density lipoproteins) promote their retention and accumulation in the arteries. This is a critical initiating factor during atherosclerosis. Macrophage catabolism of agLDL (aggregated LDL) occurs using a specialized extracellular, hydrolytic compartment, the lysosomal synapse. Compartment formation by local actin polymerization and delivery of lysosomal contents by exocytosis promotes acidification of the compartment and degradation of agLDL. Internalization of metabolites, such as cholesterol, promotes foam cell formation, a process that drives atherogenesis. Furthermore, there is accumulating evidence for the involvement of TLR4 (Toll-like receptor 4) and its adaptor protein MyD88 (myeloid differentiation primary response 88) in atherosclerosis. Here, we investigated the role of TLR4 in catabolism of agLDL using the lysosomal synapse and foam cell formation. Approach and Results: Using bone marrow-derived macrophages from knockout mice, we find that TLR4 and MyD88 regulate compartment formation, lysosome exocytosis, acidification of the compartment, and foam cell formation. Using siRNA (small interfering RNA), pharmacological inhibition and knockout bone marrow-derived macrophages, we implicate SYK (spleen tyrosine kinase), PI3K (phosphoinositide 3-kinase), and Akt in agLDL catabolism using the lysosomal synapse. Using bone marrow transplantation of LDL receptor knockout mice with TLR4 knockout bone marrow, we show that deficiency of TLR4 protects macrophages from lipid accumulation during atherosclerosis. Finally, we demonstrate that macrophages in vivo form an extracellular compartment and exocytose lysosome contents similar to that observed in vitro for degradation of agLDL. CONCLUSIONS We present a mechanism in which interaction of macrophages with agLDL initiates a TLR4 signaling pathway, resulting in formation of the lysosomal synapse, catabolism of agLDL, and lipid accumulation in vitro and in vivo.
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Affiliation(s)
- Rajesh K Singh
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Abigail S Haka
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Arky Asmal
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Valéria C Barbosa-Lorenzi
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Inna Grosheva
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Harvey F Chin
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Yuquan Xiong
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA (Y.X., T.H.).,Current address: Thoracic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY (Y.X.)
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA (Y.X., T.H.)
| | - Frederick R Maxfield
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
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Berkan Ö, Arslan S, Lalem T, Zhang L, Şahin NÖ, Aydemir EI, Korkmaz Ö, Eğilmez HR, Çekin N, Devaux Y. Regulation of microRNAs in coronary atherosclerotic plaque. Epigenomics 2019; 11:1387-1397. [PMID: 31596136 DOI: 10.2217/epi-2019-0036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Identification of microRNAs (miRNAs) associated with atherosclerosis may unravel novel therapeutic targets and biomarkers. We studied miRNAs differentially expressed between coronary atherosclerotic plaques (CAP) and healthy arteries. Materials & methods: Paired CAP and internal mammary arteries (IMA) were collected from 14 coronary artery disease patients. The miRNA profiles between diseased (CAP) and healthy (IMA) tissues were compared using microarrays and quantitative PCR. Results: Thirty-one miRNAs were differentially expressed between CAP and IMA. Among these, miR-486-5p showed a high level of regulation (12-fold), had predicted interactions with atherosclerosis-associated genes and correlated with triglyceride levels and arterial stenosis. Regulation of miR-486-5p was validated by PCR (p = 0.004). Conclusion: The miRNAs are regulated in the atherosclerotic plaque. We highlight miR-486-5p whose role in atherosclerosis requires further investigation.
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Affiliation(s)
- Öcal Berkan
- Department of Cardiovascular Surgery, Çiğli Training & Research Hospital, İzmir 35620, Turkey
| | - Serdal Arslan
- Department of Medical Biology, Faculty of Medicine, Sivas Cumhuriyet University, Sivas 58140, Turkey
| | - Torkia Lalem
- Cardiovascular Research Unit, Luxembourg Institute of Health, Strassen L-1445, Luxembourg
| | - Lu Zhang
- Cardiovascular Research Unit, Luxembourg Institute of Health, Strassen L-1445, Luxembourg
| | - Nil Özbilum Şahin
- Department of Molecular Biology & Genetics, Faculty of Science, Sivas Cumhuriyet University, Sivas 58140, Turkey
| | - Eylem Itır Aydemir
- Department of Statistics, Faculty of Science, Sivas Cumhuriyet University, Sivas 58140, Turkey
| | - Özge Korkmaz
- Department of Cardiovascular Surgery, Koru Hospital, Yüksek İhtisas University, Ankara 06510, Turkey
| | - Hatice Reyhan Eğilmez
- Department of Pathology Faculty of Medicine, Sivas Cumhuriyet University, Sivas 58140, Turkey
| | - Nilgün Çekin
- Department of Medical Biology, Faculty of Medicine, Sivas Cumhuriyet University, Sivas 58140, Turkey
| | - Yvan Devaux
- Cardiovascular Research Unit, Luxembourg Institute of Health, Strassen L-1445, Luxembourg
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Lorkowski SW, Brubaker G, Gulshan K, Smith JD. V-ATPase (Vacuolar ATPase) Activity Required for ABCA1 (ATP-Binding Cassette Protein A1)-Mediated Cholesterol Efflux. Arterioscler Thromb Vasc Biol 2019; 38:2615-2625. [PMID: 30354238 DOI: 10.1161/atvbaha.118.311814] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective- We have shown that ABCA1 (ATP-binding cassette protein A1) mediates unfolding of the apoA1 (apolipoprotein A1) N-terminal helical hairpin during apoA1 lipidation. Others have shown that an acidic pH exposes the hydrophobic surface of apoA1. We postulated that the V-ATPase (vacuolar ATPase) proton pump facilitates apoA1 unfolding and promotes ABCA1-mediated cholesterol efflux. Approach and Results- We found that V-ATPase inhibitors dose-dependently decreased ABCA1-mediated cholesterol efflux to apoA1 in baby hamster kidney cells and RAW264.7 cells; and similarly, siRNA knockdown of ATP6V0C inhibited ABCA1-mediated cholesterol efflux to apoA1 in RAW264.7 cells. Although ABCA1 expression did not alter total cellular levels of V-ATPase, ABCA1 increased the cell surface levels of the V0A1 and V1E1 subunits of V-ATPase. We generated a fluorescein isothiocyanate/Alexa647 double-labeled fluorescent ratiometric apoA1 pH indicator whose fluorescein isothiocyanate/Alexa647 emission ratio decreased as the pH drops. We found that ABCA1 induction in baby hamster kidney cells led to acidification of the cell-associated apoA1 pH indicator, compared with control cells without ABCA1 expression. The V-ATPase inhibitor bafilomycin A1 dose-dependently inhibited the apoA1 pH shift in ABCA1-expressing cells, without affecting the levels of cell-associated apoA1. However, we were not able to detect ABCA1-mediated extracellular proton release. We showed that acidic pH facilitated apoA1 unfolding, apoA1 solubilization of phosphatidycholine:phosphatidyserine liposomes, and increased lipid fluidity of these liposomes. Conclusions- Our results support a model that ABCA1 recruits V-ATPase to the plasma membrane where V-ATPase mediates apoA1 acidification and membrane remodeling that promote apoA1 unfolding and ABCA1-mediated HDL (high-density lipoprotein) biogenesis and lipid efflux.
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Affiliation(s)
- Shuhui Wang Lorkowski
- From the Department of Cellular and Molecular Medicine (S.W.L., G.B., K.G., J.D.S.), Cleveland Clinic, OH
| | - Gregory Brubaker
- From the Department of Cellular and Molecular Medicine (S.W.L., G.B., K.G., J.D.S.), Cleveland Clinic, OH
| | - Kailash Gulshan
- From the Department of Cellular and Molecular Medicine (S.W.L., G.B., K.G., J.D.S.), Cleveland Clinic, OH
| | - Jonathan D Smith
- From the Department of Cellular and Molecular Medicine (S.W.L., G.B., K.G., J.D.S.), Cleveland Clinic, OH.,Department of Cardiovascular Medicine (J.D.S.), Cleveland Clinic, OH
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Singh SK, Agrawal A. Functionality of C-Reactive Protein for Atheroprotection. Front Immunol 2019; 10:1655. [PMID: 31379851 PMCID: PMC6646712 DOI: 10.3389/fimmu.2019.01655] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
C-reactive protein (CRP) is a pentameric molecule made up of identical monomers. CRP can be seen in three different forms: native pentameric CRP (native CRP), non-native pentameric CRP (non-native CRP), and monomeric CRP (mCRP). Both native and non-native CRP execute ligand-recognition functions for host defense. The fate of any pentameric CRP after binding to a ligand is dissociation into ligand-bound mCRP. If ligand-bound mCRP is proinflammatory, like free mCRP has been shown to be in vitro, then mCRP along with the bound ligand must be cleared from the site of inflammation. Once pentameric CRP is bound to atherogenic low-density lipoprotein (LDL), it reduces both formation of foam cells and proinflammatory effects of atherogenic LDL. A CRP mutant, that is non-native CRP, which readily binds to atherogenic LDL, has been found to be atheroprotective in a murine model of atherosclerosis. Thus, unlike statins, a drug that can lower only cholesterol levels but not CRP levels should be developed. Since non-native CRP has been shown to bind to all kinds of malformed proteins in general, it is possible that non-native CRP would be protective against all inflammatory states in which host proteins become pathogenic. If it is proven through experimentation employing transgenic mice that non-native CRP is beneficial for the host, then using a small-molecule compound to target CRP with the goal of changing the conformation of endogenous native CRP would be preferred over using recombinant non-native CRP as a biologic to treat diseases caused by pathogenic proteins such as oxidized LDL.
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Affiliation(s)
| | - Alok Agrawal
- Department of Biomedical Sciences, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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Zhang H, Reilly MP. LIPA Variants in Genome-Wide Association Studies of Coronary Artery Diseases: Loss-of-Function or Gain-of-Function? Arterioscler Thromb Vasc Biol 2019; 37:1015-1017. [PMID: 28539489 DOI: 10.1161/atvbaha.117.309344] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Hanrui Zhang
- From the Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York (H.Z., M.P.R.); and Irving Institute for Clinical and Translational Research, Columbia University, New York (M.P.R.)
| | - Muredach P Reilly
- From the Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York (H.Z., M.P.R.); and Irving Institute for Clinical and Translational Research, Columbia University, New York (M.P.R.).
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Öörni K, Lehti S, Sjövall P, Kovanen PT. Triglyceride-Rich Lipoproteins as a Source of Proinflammatory Lipids in the Arterial Wall. Curr Med Chem 2019; 26:1701-1710. [DOI: 10.2174/0929867325666180530094819] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/27/2017] [Accepted: 01/01/2018] [Indexed: 12/11/2022]
Abstract
Apolipoprotein B –containing lipoproteins include triglyceride-rich lipoproteins
(chylomicrons and their remnants, and very low-density lipoproteins and their remnants) and
cholesterol-rich low-density lipoprotein particles. Of these, lipoproteins having sizes below
70-80 nm may enter the arterial wall, where they accumulate and induce the formation of
atherosclerotic lesions. The processes that lead to accumulation of lipoprotein-derived lipids
in the arterial wall have been largely studied with a focus on the low-density lipoprotein particles.
However, recent observational and genetic studies have discovered that the triglyceriderich
lipoproteins and their remnants are linked with cardiovascular disease risk. In this review,
we describe the potential mechanisms by which the triglyceride-rich remnant lipoproteins can
contribute to the development of atherosclerotic lesions, and highlight the differences in the
atherogenicity between low-density lipoproteins and the remnant lipoproteins.
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Affiliation(s)
| | - Satu Lehti
- Wihuri Research Institute, Helsinki, Finland
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Nambayan RJT, Sandin SI, Quint DA, Satyadi DM, de Alba E. The inflammasome adapter ASC assembles into filaments with integral participation of its two Death Domains, PYD and CARD. J Biol Chem 2019; 294:439-452. [PMID: 30459235 PMCID: PMC6333874 DOI: 10.1074/jbc.ra118.004407] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 11/17/2018] [Indexed: 11/06/2022] Open
Abstract
The inflammasome is a multiprotein complex necessary for the onset of inflammation. The adapter protein ASC assembles inflammasome components by acting as a molecular glue between danger-signal sensors and procaspase-1. The assembly is mediated by ASC self-association and protein interactions via its two Death Domains, PYD and CARD. Truncated versions of ASC have been shown to form filaments, but information on the filaments formed by full-length ASC is needed to construct a meaningful model of inflammasome assembly. To gain insights into this system, we used a combination of transmission EM, NMR, and computational analysis to investigate intact ASC structures. We show that ASC forms ∼6-7-nm-wide filaments that stack laterally to form bundles. The structural characteristics and dimensions of the bundles indicate that both PYD and CARD are integral parts of the filament. A truncated version of ASC with only the CARD domain (ASCCARD) forms different filaments (∼3-4-nm width), providing further evidence that both domains work in concert in filament assembly. Ring-shaped protein particles bound to pre-existing filaments match the size of ASC dimer structures generated by NMR-based protein docking, suggesting that the ASC dimer could be a basic building block for filament formation. Solution NMR binding studies identified the protein surfaces involved in the ASCCARD-ASCCARD interaction. These data provide new insights into the structural underpinnings of the inflammasome and should inform future efforts to interrogate this important biological system.
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Affiliation(s)
| | - Suzanne I Sandin
- From the Department of Bioengineering
- Chemistry and Chemical Biology Graduate Program
| | - David A Quint
- NSF-CREST Center for Cellular and Biomolecular Machines, and
- Department of Physics, University of California, Merced, California 95343
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42
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Russo L, Lumeng CN. Properties and functions of adipose tissue macrophages in obesity. Immunology 2018; 155:407-417. [PMID: 30229891 DOI: 10.1111/imm.13002] [Citation(s) in RCA: 370] [Impact Index Per Article: 61.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/06/2018] [Accepted: 09/07/2018] [Indexed: 12/12/2022] Open
Abstract
The expansion of adipose tissue (AT) in obesity is accompanied by the accumulation of immune cells that contribute to a state of low-grade, chronic inflammation and dysregulated metabolism. Adipose tissue macrophages (ATMs) represent the most abundant class of leukocytes in AT and are involved in the regulation of several regulatory physiological processes, such as tissue remodeling and insulin sensitivity. With progressive obesity, ATMs are key mediators of meta-inflammation, insulin resistance and impairment of adipocyte function. While macrophage recruitment from blood monocytes is a critical component of the generation of AT inflammation, new studies have revealed a role for ATM proliferation in the early stages of obesity and in sustaining AT inflammation. In addition, studies have revealed a more complex range of macrophage activation states than the previous M1/M2 model, and the existence of different macrophage profiles between human and animal models. This review will summarize the current understanding of the regulatory mechanisms of ATM function in relation to obesity, type 2 diabetes, depot of origin, and to other leukocytes such as AT dendritic cells, with hopes of emphasizing the regulatory nodes that can potentially be targeted to prevent and treat obesity-related metabolic disorders.
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Affiliation(s)
- Lucia Russo
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Carey N Lumeng
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI, USA.,Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
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Development and Evaluation of an Injectable Chitosan/β-Glycerophosphate Paste as a Local Antibiotic Delivery System for Trauma Care. J Funct Biomater 2018; 9:jfb9040056. [PMID: 30322006 PMCID: PMC6306749 DOI: 10.3390/jfb9040056] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 09/23/2018] [Accepted: 10/09/2018] [Indexed: 01/03/2023] Open
Abstract
Complex open musculoskeletal wounds are a leading cause of morbidity worldwide, partially due to a high risk of bacterial contamination. Local delivery systems may be used as adjunctive therapies to prevent infection, but they may be nondegradable, possess inadequate wound coverage, or migrate from the wound site. To address this issue, a thermo-responsive, injectable chitosan paste was fabricated by incorporating beta-glycerophosphate. The efficacy of thermo-paste as an adjunctive infection prevention tool was evaluated in terms of cytocompatibility, degradation, antibacterial, injectability, and inflammation properties. In vitro studies demonstrated thermo-paste may be loaded with amikacin and vancomycin and release inhibitory levels for at least 3 days. Further, approximately 60% of thermo-paste was enzymatically degraded within 7 days in vitro. The viability of cells exposed to thermo-paste exceeded ISO 10993-5 standards with approximately 73% relative viability of a control chitosan sponge. The ejection force of thermo-paste, approximately 20 N, was lower than previously studied paste formulations and within relevant clinical ejection force ranges. An in vivo murine biocompatibility study demonstrated that thermo-paste induced minimal inflammation after implantation for 7 days, similar to previously developed chitosan pastes. Results from these preliminary preclinical studies indicate that thermo-paste shows promise for further development as an antibiotic delivery system for infection prevention.
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Reduced Microglial Activity and Enhanced Glutamate Transmission in the Basolateral Amygdala in Early CNS Autoimmunity. J Neurosci 2018; 38:9019-9033. [PMID: 30185466 DOI: 10.1523/jneurosci.0398-18.2018] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 11/21/2022] Open
Abstract
Emotional dysfunction is common in multiple sclerosis (MS) patients and in mouse models of MS, including experimental autoimmune encephalomyelitis (EAE); however, the etiology of these behaviors is poorly understood. To identify CNS changes associated with these behaviors, we focused on the basolateral amygdala (BLA) because of its central role in the regulation of emotional behavior. Whole-cell recordings were performed in the principal neurons of the BLA in early EAE, before demyelination, T-cell invasion, and motor dysfunction. EAE female mice displayed increased frequency of mEPSCs, with no alteration in amplitude or evoked EPSC paired-pulse ratio compared with controls. We found an increase in the AMPA-NMDA ratio and dendritic spine density, indicating increased numbers of glutamatergic synapses. We saw similar electrophysiological changes in BLA principal neurons after microglia were either inactivated (minocycline) or depleted (Mac1-Saporin) in the BLA. Microglia regulate synapses through pruning, directed by complement protein 3 (C3) expression. C3 was downregulated in the BLA in EAE. Ultrastructural analysis of microglia revealed more complex ramifications and reduced extracellular digestion of cellular elements. We also observed reduced IBA-1 and CD68 staining and lack of proinflammatory cytokine expression in the amygdala. Thus, early EAE is a state of microglial "deactivation" associated with reduced synaptic pruning. This contrasts with the prototypic microglial activation commonly associated with inflammatory CNS disease. Additionally, these data support a role for the acquired immune system to influence both neuronal and microglial function in early CNS autoimmunity.SIGNIFICANCE STATEMENT Microglia help regulate synaptic homeostasis, but there has been little evidence for how this might be important in neuroinflammatory diseases. The data from this study reveal increased synaptic activity and spine density in early stages of experimental autoimmune encephalomyelitis (an animal model of multiple sclerosis) in the basolateral amygdala, a nucleus important in the types of behavioral changes we have previously described. These electrophysiological and morphological effects occurred without significant elevation of local inflammatory cytokines or local demyelination. Unexpectedly, in the context of inflammatory state, we found that microglia were "deactivated." This study provides strong evidence for a link between microglial activity and synaptic function; the conclusions contrast with the generally accepted view that microglia are activated in inflammatory disease.
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45
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Progranulin in the hematopoietic compartment protects mice from atherosclerosis. Atherosclerosis 2018; 277:145-154. [PMID: 30212683 DOI: 10.1016/j.atherosclerosis.2018.08.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 08/15/2018] [Accepted: 08/29/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND AND AIMS Progranulin is a circulating protein that modulates inflammation and is found in atherosclerotic lesions. Here we determined whether inflammatory cell-derived progranulin impacts atherosclerosis development. METHODS Ldlr-/- mice were transplanted with bone marrow from wild-type (WT) or Grn-/- (progranulin KO) mice (referred to as Tx-WT and Tx-KO, respectively). RESULTS After 10 weeks of high-fat diet feeding, both groups displayed similarly elevated plasma levels of cholesterol and triglycerides. Despite abundant circulating levels of progranulin, the size of atherosclerotic lesions in Tx-KO mice was increased by 47% in aortic roots and by 62% in whole aortas. Aortic root lesions in Tx-KO mice had increased macrophage content and larger necrotic cores, consistent with more advanced lesions. Progranulin staining was markedly reduced in the lesions of Tx-KO mice, indicating little or no uptake of circulating progranulin. Mechanistically, cultured progranulin-deficient macrophages exhibited increased lysosome-mediated exophagy of aggregated low-density lipoproteins resulting in increased cholesterol uptake and foam cell formation. CONCLUSIONS We conclude that hematopoietic progranulin deficiency promotes diet-induced atherosclerosis in Ldlr-/- mice, possibly due to increased exophagy-mediated cholesterol uptake. Circulating progranulin was unable to prevent the increased lesion development, consistent with the importance of progranulin acting via cell-autonomous or local effects.
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Abstract
PURPOSE OF REVIEW Lysosomal acid lipase (LAL), encoded by the LIPA gene, is an essential lysosomal enzyme that hydrolyzes cholesteryl ester and triglyceride delivered to the lysosome. This review highlights the novel pathophysiological role of LAL, the functional genomic discoveries of LIPA as a risk locus for coronary heart diseases (CHD), and the clinical advance in therapies for LAL deficiency. RECENT FINDINGS The essential role of LAL in lipid metabolism has been confirmed in human and mice with LAL deficiency. In humans, loss-of-function mutations of LIPA cause rare lysosomal disorders, Wolman disease, and cholesteryl ester storage disease, in which LAL enzyme replacement therapy has shown significant benefits in a phase 3 clinical trial. Recent studies have revealed the role of LAL-mediated lysosomal lipolysis in regulating macrophage M2 polarization, lipid mediator production, VLDL secretion, lysosomal function and autophagy, extracellular degradation of aggregated-LDL, and adipose tissue lipolysis. Genome-wide association studies and functional genomic studies have identified LIPA as a risk locus for CHD, but the causal variants and mechanisms remain to be determined. SUMMARY Despite years of research, our understanding of LAL is incomplete. Future studies will continue to focus on the key pathophysiological functions of LAL in health and diseases including CHD.
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Affiliation(s)
- Hanrui Zhang
- Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York, New York, USA
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47
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Zechner R, Madeo F, Kratky D. Cytosolic lipolysis and lipophagy: two sides of the same coin. Nat Rev Mol Cell Biol 2017; 18:671-684. [DOI: 10.1038/nrm.2017.76] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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48
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Singh RK, Haka AS, Brumfield A, Grosheva I, Bhardwaj P, Chin HF, Xiong Y, Hla T, Maxfield FR. Ceramide activation of RhoA/Rho kinase impairs actin polymerization during aggregated LDL catabolism. J Lipid Res 2017; 58:1977-1987. [PMID: 28814641 PMCID: PMC5625121 DOI: 10.1194/jlr.m076398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 08/11/2017] [Indexed: 01/22/2023] Open
Abstract
Macrophages use an extracellular, hydrolytic compartment formed by local actin polymerization to digest aggregated LDL (agLDL). Catabolism of agLDL promotes foam cell formation and creates an environment rich in LDL catabolites, including cholesterol and ceramide. Increased ceramide levels are present in lesional LDL, but the effect of ceramide on macrophage proatherogenic processes remains unknown. Here, we show that macrophages accumulate ceramide in atherosclerotic lesions. Using macrophages from sphingosine kinase 2 KO (SK2KO) mice to mimic ceramide-rich conditions of atherosclerotic lesions, we show that SK2KO macrophages display impaired actin polymerization and foam cell formation in response to contact with agLDL. C16-ceramide treatment impaired wild-type but not SK2KO macrophage actin polymerization, confirming that this effect is due to increased ceramide levels. We demonstrate that knockdown of RhoA or inhibition of Rho kinase restores agLDL-induced actin polymerization in SK2KO macrophages. Activation of RhoA in macrophages was sufficient to impair actin polymerization and foam cell formation in response to agLDL. Finally, we establish that during catabolism, macrophages take up ceramide from agLDL, and inhibition of ceramide generation modulates actin polymerization. These findings highlight a critical regulatory pathway by which ceramide impairs actin polymerization through increased RhoA/Rho kinase signaling and regulates foam cell formation.
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Affiliation(s)
- Rajesh K Singh
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Abigail S Haka
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | | | - Inna Grosheva
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Priya Bhardwaj
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Harvey F Chin
- Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065
| | - Yuquan Xiong
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA 02115
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA 02115
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Ioannou GN, Subramanian S, Chait A, Haigh WG, Yeh MM, Farrell GC, Lee SP, Savard C. Cholesterol crystallization within hepatocyte lipid droplets and its role in murine NASH. J Lipid Res 2017; 58:1067-1079. [PMID: 28404639 DOI: 10.1194/jlr.m072454] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 04/03/2017] [Indexed: 12/21/2022] Open
Abstract
We recently reported that cholesterol crystals form in hepatocyte lipid droplets (LDs) in human and experimental nonalcoholic steatohepatitis. Herein, we assigned WT C57BL/6J mice to a high-fat (15%) diet for 6 months, supplemented with 0%, 0.25%, 0.5%, 0.75%, or 1% dietary cholesterol. Increasing dietary cholesterol led to cholesterol loading of the liver, but not of adipose tissue, resulting in fibrosing steatohepatitis at a dietary cholesterol concentration of ≥0.5%, whereas mice on lower-cholesterol diets developed only simple steatosis. Hepatic cholesterol crystals and crown-like structures also developed at a dietary cholesterol concentration ≥0.5%. Crown-like structures consisted of activated Kupffer cells (KCs) staining positive for NLRP3 and activated caspase 1, which surrounded and processed cholesterol crystal-containing remnant LDs of dead hepatocytes. The KCs processed LDs at the center of crown-like structures in the extracellular space by lysosomal enzymes, ultimately transforming into lipid-laden foam cells. When HepG2 cells were exposed to LDL cholesterol, they developed cholesterol crystals in LD membranes, which caused activation of THP1 cells (macrophages) grown in coculture; upregulation of TNF-alpha, NLRP3, and interleukin 1beta (IL1β) mRNA; and secretion of IL-1beta. In conclusion, cholesterol crystals form on the LD membrane of hepatocytes and cause activation and cholesterol loading of KCs that surround and process these LDs by lysosomal enzymes.
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Affiliation(s)
- George N Ioannou
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA .,Division of Gastroenterology, University of Washington, Seattle, WA
| | - Savitha Subramanian
- Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, WA
| | - Alan Chait
- Division of Metabolism, Endocrinology and Nutrition, University of Washington, Seattle, WA
| | - W Geoffrey Haigh
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA
| | - Matthew M Yeh
- Department of Pathology, University of Washington, Seattle, WA
| | - Geoffrey C Farrell
- Liver Research Group, Australian National University Medical School at the Canberra Hospital, Garran, ACT, Australia
| | - Sum P Lee
- Division of Gastroenterology, University of Washington, Seattle, WA
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA.,Division of Gastroenterology, University of Washington, Seattle, WA
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Chellan B, Reardon CA, Getz GS, Hofmann Bowman MA. Enzymatically Modified Low-Density Lipoprotein Promotes Foam Cell Formation in Smooth Muscle Cells via Macropinocytosis and Enhances Receptor-Mediated Uptake of Oxidized Low-Density Lipoprotein. Arterioscler Thromb Vasc Biol 2016; 36:1101-13. [PMID: 27079883 DOI: 10.1161/atvbaha.116.307306] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 03/31/2016] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Enzyme-modified nonoxidized low-density lipoprotein (ELDL) is present in human atherosclerotic lesions. Our objective is to understand the mechanisms of ELDL uptake and its effects on vascular smooth muscle cells (SMC). APPROACH AND RESULTS Transformation of murine aortic SMCs into foam cells in response to ELDL was analyzed. ELDL, but not acetylated or oxidized LDL, was potent in inducing SMC foam cell formation. Inhibitors of macropinocytosis (LY294002, wortmannin, amiloride) attenuated ELDL uptake. In contrast, inhibitors of receptor-mediated endocytosis (dynasore, sucrose) and inhibitor of caveolae-/lipid raft-mediated endocytosis (filipin) had no effect on ELDL uptake in SMC, suggesting that macropinocytosis is the main mechanism of ELDL uptake by SMC. Receptor for advanced glycation end products (RAGE) is not obligatory for ELDL-induced SMC foam cell formation, but primes SMC for the uptake of oxidized LDL in a RAGE-dependent manner. ELDL increased intracellular reactive oxygen species, cytosolic calcium, and expression of lectin-like oxidized LDL receptor-1 in wild-type SMC but not in RAGE(-/-) SMC. The macropinocytotic uptake of ELDL is regulated predominantly by intracellular calcium because ELDL uptake was completely inhibited by pretreatment with the calcium channel inhibitor lacidipine in wild-type and RAGE(-/-) SMC. This is in contrast to pretreatment with PI3 kinase inhibitors which completely prevented ELDL uptake in RAGE(-/-) SMC, but only partially in wild-type SMC. CONCLUSIONS ELDL is highly potent in inducing foam cells in murine SMC. ELDL endocytosis is mediated by calcium-dependent macropinocytosis. Priming SMC with ELDL enhances the uptake of oxidized LDL.
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Affiliation(s)
- Bijoy Chellan
- From the Department of Medicine (B.C., M.A.H.B.), and Department of Pathology (C.A.R., G.S.G), University of Chicago, IL.
| | - Catherine A Reardon
- From the Department of Medicine (B.C., M.A.H.B.), and Department of Pathology (C.A.R., G.S.G), University of Chicago, IL
| | - Godfrey S Getz
- From the Department of Medicine (B.C., M.A.H.B.), and Department of Pathology (C.A.R., G.S.G), University of Chicago, IL
| | - Marion A Hofmann Bowman
- From the Department of Medicine (B.C., M.A.H.B.), and Department of Pathology (C.A.R., G.S.G), University of Chicago, IL.
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