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Huang X, Cao M, Xiao Y. Alveolar macrophages in pulmonary alveolar proteinosis: origin, function, and therapeutic strategies. Front Immunol 2023; 14:1195988. [PMID: 37388737 PMCID: PMC10303123 DOI: 10.3389/fimmu.2023.1195988] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/31/2023] [Indexed: 07/01/2023] Open
Abstract
Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disorder that is characterized by the abnormal accumulation of surfactant within the alveoli. Alveolar macrophages (AMs) have been identified as playing a pivotal role in the pathogenesis of PAP. In most of PAP cases, the disease is triggered by impaired cholesterol clearance in AMs that depend on granulocyte-macrophage colony-stimulating factor (GM-CSF), resulting in defective alveolar surfactant clearance and disruption of pulmonary homeostasis. Currently, novel pathogenesis-based therapies are being developed that target the GM-CSF signaling, cholesterol homeostasis, and immune modulation of AMs. In this review, we summarize the origin and functional role of AMs in PAP, as well as the latest therapeutic strategies aimed at addressing this disease. Our goal is to provide new perspectives and insights into the pathogenesis of PAP, and thereby identify promising new treatments for this disease.
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Affiliation(s)
- Xinmei Huang
- Department of Respiratory and Critical Care Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Nanjing Institute of Respiratory Diseases, Nanjing, China
| | - Mengshu Cao
- Department of Respiratory and Critical Care Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Nanjing Institute of Respiratory Diseases, Nanjing, China
- Department of Respiratory and Critical Care Medicine, Nanjing Drum Tower Hospital Clinical College of Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, China
- Department of Respiratory and Critical Care Medicine, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, China
| | - Yonglong Xiao
- Department of Respiratory and Critical Care Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Nanjing Institute of Respiratory Diseases, Nanjing, China
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2
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Antoniu SA, Rajnoveanu R, Grigore M, Antohe I. Pharmacotherapy options in pulmonary alveolar proteinosis. Expert Opin Pharmacother 2020; 21:1359-1366. [PMID: 32511020 DOI: 10.1080/14656566.2020.1757650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Pulmonary alveolar proteinosis (PAP) is a heterogeneous group of rare diseases characterized by the abnormal production and impaired degradation of pulmonary surfactant as a result of malfunctioning of alveolar macrophages. This is due to the downstream dysregulation of the GM-CSF pathway, which can be caused by specific autoantibodies (autoimmune, aPAP formerly known as idiopathic iPAP), direct injury to alveolar macrophages (e.g. by toxic inhaled agents.), or by genetic defects (hereditary or congenital PAP). Few pharmacotherapy options are currently available to treat this disease. AREA COVERED The authors discuss the exogenous administration of GM-CSF, rituximab, and the potential role of cholesterol lowering medications in this review. The authors, furthermore, provide their opinion on the available pharmacotherapeutic options and give their future perspectives. EXPERT OPINION Inhaled GM-CSF remains the most commonly used therapy in patients with iPAP but other inhaled therapies such as PPARγ activators should be considered, especially in patients who are partially responsive or unresponsive to traditional treatments.
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Affiliation(s)
| | - Ruxandra Rajnoveanu
- Faculty of Medicine, University of Medicine and Pharmacy Iuliu Hatieganu , Cluj Napoca, Romania
| | - Mihaela Grigore
- Mother and Child Department, University of Medicine and Pharmacy Grigore T Popa , Iasi, Romania
| | - Ileana Antohe
- Faculty of Medicine, University of Medicine and Pharmacy Grigore T Popa , Iasi, Romania
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3
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McPeek M, Malur A, Tokarz DA, Lertpiriyapong K, Gowdy KM, Murray G, Wingard CJ, Fessler MB, Barna BP, Thomassen MJ. Alveolar Macrophage ABCG1 Deficiency Promotes Pulmonary Granulomatous Inflammation. Am J Respir Cell Mol Biol 2020; 61:332-340. [PMID: 30848658 DOI: 10.1165/rcmb.2018-0365oc] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Pulmonary granuloma formation is a complex and poorly understood response to inhaled pathogens and particulate matter. To explore the mechanisms of pulmonary granuloma formation and maintenance, our laboratory has developed a multiwall carbon nanotube (MWCNT)-induced murine model of chronic granulomatous inflammation. We have demonstrated that the MWCNT model closely mimics pulmonary sarcoidosis pathophysiology, including the deficiency of alveolar macrophage ATP-binding cassette (ABC) lipid transporters ABCA1 and ABCG1. We hypothesized that deficiency of alveolar macrophage ABCA1 and ABCG1 would promote pulmonary granuloma formation and inflammation. To test this hypothesis, the effects of MWCNT instillation were evaluated in ABCA1, ABCG1, and ABCA1/ABCG1 myeloid-specific knockout (KO) mice. Histological examination revealed significantly larger pulmonary granulomas in ABCG1-KO and ABCA1/ABCG1 double-KO animals when compared with wild-type animals. Evaluation of BAL cells indicated increased expression of CCL2 and osteopontin, genes shown to be involved in the formation and maintenance of pulmonary granulomas. Single deficiency of alveolar macrophage ABCA1 did not affect MWCNT-induced granuloma formation or proinflammatory gene expression. These observations indicate that the deficiency of alveolar macrophage ABCG1 promotes pulmonary granulomatous inflammation and that this is augmented by additional deletion of ABCA1.
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Affiliation(s)
- Matthew McPeek
- Program in Lung Cell Biology and Translational Research, Division of Pulmonary, Critical Care and Sleep Medicine
| | - Anagha Malur
- Program in Lung Cell Biology and Translational Research, Division of Pulmonary, Critical Care and Sleep Medicine
| | - Debra A Tokarz
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina
| | - Kvin Lertpiriyapong
- Center of Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center, New York, New York
| | | | - Gina Murray
- Department of Pathology, East Carolina University, Greenville, North Carolina
| | - Christopher J Wingard
- School of Movement and Rehabilitation Sciences, Physical Therapy Program, Bellarmine University, Louisville, Kentucky; and
| | - Michael B Fessler
- Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Barbara P Barna
- Program in Lung Cell Biology and Translational Research, Division of Pulmonary, Critical Care and Sleep Medicine
| | - Mary Jane Thomassen
- Program in Lung Cell Biology and Translational Research, Division of Pulmonary, Critical Care and Sleep Medicine
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Slovinsky WS, Romero F, Sales D, Shaghaghi H, Summer R. The involvement of GM-CSF deficiencies in parallel pathways of pulmonary alveolar proteinosis and the alcoholic lung. Alcohol 2019; 80:73-79. [PMID: 31229291 DOI: 10.1016/j.alcohol.2018.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/09/2018] [Accepted: 07/12/2018] [Indexed: 12/24/2022]
Abstract
Chronic alcohol consumption renders the lung more susceptible to infections by disrupting essential alveolar macrophage functions. Emerging evidence suggests that these functional deficits are due, in part, to a suppression of GM-CSF signaling, which is believed to compromise monocyte growth and maturation in the lung. However, in addition to controlling monocyte behaviors, GM-CSF also regulates surfactant homeostasis. For example, mice with targeted deletion of the gene for GM-CSF accumulate large amounts of surfactant phospholipids in their lungs. Moreover, decreased GM-CSF signaling in humans has been linked to the development of pulmonary alveolar proteinosis (PAP), a rare disorder in which surfactant lipids and proteins accumulate in alveolar macrophages and the lung exhibits enhanced susceptibility to infection. Consistent with parallel mechanisms in the PAP and alcoholic lung, we have recently reported that levels of intrapulmonary lipids, specifically triglycerides and free fatty acids, are increased in BAL fluid, whole lung digests and alveolar macrophages of chronically alcohol exposed rats. Additionally, we showed that uptake of saturated fatty acids alone could induce phenotypic and functional changes in alveolar macrophages that mimicked those in the alcohol-exposed rat and human lung. Herein, we discuss the role of GM-CSF in surfactant homeostasis and highlight the evidence that links decreased GM-CSF signaling to alveolar macrophage dysfunction in both the PAP and alcohol-exposed lung. Moreover, we discuss how lipid accumulation itself might contribute to altering alveolar macrophage function and propose how targeting these mechanisms could be employed for reducing the susceptibility to pulmonary infections in alcoholics.
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Affiliation(s)
- William S Slovinsky
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Freddy Romero
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Dominic Sales
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Hoora Shaghaghi
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Ross Summer
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Thomas Jefferson University, Philadelphia, PA, 19107, USA.
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Critical Role of the Human ATP-Binding Cassette G1 Transporter in Cardiometabolic Diseases. Int J Mol Sci 2017; 18:ijms18091892. [PMID: 28869506 PMCID: PMC5618541 DOI: 10.3390/ijms18091892] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 12/15/2022] Open
Abstract
ATP-binding cassette G1 (ABCG1) is a member of the large family of ABC transporters which are involved in the active transport of many amphiphilic and lipophilic molecules including lipids, drugs or endogenous metabolites. It is now well established that ABCG1 promotes the export of lipids, including cholesterol, phospholipids, sphingomyelin and oxysterols, and plays a key role in the maintenance of tissue lipid homeostasis. Although ABCG1 was initially proposed to mediate cholesterol efflux from macrophages and then to protect against atherosclerosis and cardiovascular diseases (CVD), it becomes now clear that ABCG1 exerts a larger spectrum of actions which are of major importance in cardiometabolic diseases (CMD). Beyond a role in cellular lipid homeostasis, ABCG1 equally participates to glucose and lipid metabolism by controlling the secretion and activity of insulin and lipoprotein lipase. Moreover, there is now a growing body of evidence suggesting that modulation of ABCG1 expression might contribute to the development of diabetes and obesity, which are major risk factors of CVD. In order to provide the current understanding of the action of ABCG1 in CMD, we here reviewed major findings obtained from studies in mice together with data from the genetic and epigenetic analysis of ABCG1 in the context of CMD.
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George L, Mitra A, Thimraj TA, Irmler M, Vishweswaraiah S, Lunding L, Hühn D, Madurga A, Beckers J, Fehrenbach H, Upadhyay S, Schulz H, Leikauf GD, Ganguly K. Transcriptomic analysis comparing mouse strains with extreme total lung capacities identifies novel candidate genes for pulmonary function. Respir Res 2017; 18:152. [PMID: 28793908 PMCID: PMC5551015 DOI: 10.1186/s12931-017-0629-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/25/2017] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Failure to attain peak lung function by early adulthood is a risk factor for chronic lung diseases. Previously, we reported that C3H/HeJ mice have about twice total lung capacity (TLC) compared to JF1/MsJ mice. We identified seven lung function quantitative trait loci (QTL: Lfnq1-Lfnq7) in backcross/intercross mice derived from these inbred strains. We further demonstrated, superoxide dismutase 3, extracellular (Sod3), Kit oncogene (Kit) and secreted phosphoprotein 1 (Spp1) located on these Lfnqs as lung function determinants. Emanating from the concept of early origin of lung disease, we sought to identify novel candidate genes for pulmonary function by investigating lung transcriptome in C3H/HeJ and JF1/MsJ mice at the completion of embryonic development, bulk alveolar formation and maturity. METHODS Design-based stereological analysis was performed to study lung structure in C3H/HeJ and JF1/MsJ mice. Microarray was used for lung transcriptomic analysis [embryonic day 18, postnatal days 28, 70]. Quantitative real time polymerase chain reaction (qRT-PCR), western blot and immunohistochemical analysis were used to confirm selected differences. RESULTS Stereological analysis revealed decreased alveolar number density, elastin to collagen ratio and increased mean alveolar volume in C3H/HeJ mice compared to JF1/MsJ. Gene ontology term "extracellular region" was enriched among the decreased JF1/MsJ transcripts. Candidate genes identified using the expression-QTL strategy include: ATP-binding cassette, sub-family G (WHITE), member 1 (Abcg1), formyl peptide receptor 1 (Fpr1), gamma-aminobutyric acid (GABA) B receptor, 1 (Gabbr1); histocompatibility 2 genes: class II antigen E beta (H2-Eb1), D region locus 1 (H2-D1), and Q region locus 4 (H2-Q4); leucine rich repeat containing 6 (testis) (Lrrc6), radial spoke head 1 homolog (Rsph1), and surfactant associated 2 (Sfta2). Noteworthy genes selected as candidates for their consistent expression include: Wnt inhibitor factor 1 (Wif1), follistatin (Fst), chitinase-like 1 (Chil1), and Chil3. CONCLUSIONS Comparison of late embryonic, adolescent and adult lung transcript profiles between mouse strains with extreme TLCs lead to the identification of candidate genes for pulmonary function that has not been reported earlier. Further mechanistic investigations are warranted to elucidate their mode of action in determining lung function.
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Affiliation(s)
- Leema George
- SRM Research Institute, SRM University, Chennai, 603203 India
| | - Ankita Mitra
- SRM Research Institute, SRM University, Chennai, 603203 India
| | | | - Martin Irmler
- Institute of Experimental Genetics, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg, Munich Germany
| | | | - Lars Lunding
- Priority Area Asthma & Allergy, Division of Asthma Exacerbation & Regulation, Research Center Borstel, Airway Research Center North (ARCN), 23845 Borstel, Germany
| | - Dorothea Hühn
- Department of Medicine, Pulmonary and Critical Care Medicine, University Medical Centre Giessen and Marburg, Philipps-University Marburg, Marburg, Germany
- Present address: Lahn-Dill-Kliniken, Klinikum Wetzlar, Medizinische Klinik II, Forsthausstraße 1, D-35578 Wetzlar, Germany
| | - Alicia Madurga
- Department of Internal Medicine (Pulmonology), University of Giessen and Marburg Lung Center (UGMLC), 35392, Giessen, Germany
| | - Johannes Beckers
- Institute of Experimental Genetics, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg, Munich Germany
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
- Experimental Genetics, Technische Universität München, 85354 Freising, Germany
| | - Heinz Fehrenbach
- Priority Area Asthma & Allergy, Division of Experimental Pneumology, Research Center Borstel, Airway Research Center North (ARCN), 23845 Borstel, Germany
| | - Swapna Upadhyay
- Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet, Box 287, SE-171 77 Stockholm, Sweden
- Institute of Lung Biology and Disease, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg, Munich Germany
| | - Holger Schulz
- Institute of Epidemiology I, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg, Munich Germany
- Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany
| | - George D. Leikauf
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219 USA
| | - Koustav Ganguly
- SRM Research Institute, SRM University, Chennai, 603203 India
- Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet, Box 287, SE-171 77 Stockholm, Sweden
- Institute of Lung Biology and Disease, Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, 85764 Neuherberg, Munich Germany
- Work Environment Toxicology; Institute of Environmental Medicine, Karolinska Institutet, Box 287, SE-171 77 Stockholm, Sweden
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7
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Brandsma J, Postle AD. Analysis of the regulation of surfactant phosphatidylcholine metabolism using stable isotopes. Ann Anat 2017; 211:176-183. [PMID: 28351529 DOI: 10.1016/j.aanat.2017.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 02/27/2017] [Accepted: 02/28/2017] [Indexed: 01/22/2023]
Abstract
The pathways and mechanisms that regulate pulmonary surfactant synthesis, processing, secretion and catabolism have been extensively characterised using classical biochemical and analytical approaches. These have constructed a model, largely in experimental animals, for surfactant phospholipid metabolism in the alveolar epithelial cell whereby phospholipid synthesised on the endoplasmic reticulum is selectively transported to lamellar body storage vesicles, where it is subsequently processed before secretion into the alveolus. Surfactant phospholipid is a complex mixture of individual molecular species defined by the combination of esterified fatty acid groups and a comprehensive description of surfactant phospholipid metabolism requires consideration of the interactions between such molecular species. However, until recently, lipid analytical techniques have not kept pace with the considerable advances in understanding of the enzymology and molecular biology of surfactant metabolism. Refinements in electrospray ionisation mass spectrometry (ESI-MS) can now provide very sensitive platforms for the rapid characterisation of surfactant phospholipid composition in molecular detail. The combination of ESI-MS and administration of phospholipid substrates labelled with stable isotopes extends this analytical approach to the quantification of synthesis and turnover of individual molecular species of surfactant phospholipid. As this methodology does not involve radioactivity, it is ideally suited to application in clinical studies. This review will provide an overview of the metabolic processes that regulate the molecular specificity of surfactant phosphatidylcholine together with examples of how the application of stable isotope technologies in vivo has, for the first time, begun to explore regulation of the molecular specificity of surfactant synthesis in human subjects.
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Affiliation(s)
- Joost Brandsma
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, United Kingdom
| | - Anthony D Postle
- Academic Unit of Clinical & Experimental Sciences, Faculty of Medicine, University of Southampton, United Kingdom.
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de Aguiar Vallim TQ, Lee E, Merriott DJ, Goulbourne CN, Cheng J, Cheng A, Gonen A, Allen RM, Palladino END, Ford DA, Wang T, Baldán Á, Tarling EJ. ABCG1 regulates pulmonary surfactant metabolism in mice and men. J Lipid Res 2017; 58:941-954. [PMID: 28264879 DOI: 10.1194/jlr.m075101] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/03/2017] [Indexed: 12/27/2022] Open
Abstract
Idiopathic pulmonary alveolar proteinosis (PAP) is a rare lung disease characterized by accumulation of surfactant. Surfactant synthesis and secretion are restricted to epithelial type 2 (T2) pneumocytes (also called T2 cells). Clearance of surfactant is dependent upon T2 cells and macrophages. ABCG1 is highly expressed in both T2 cells and macrophages. ABCG1-deficient mice accumulate surfactant, lamellar body-loaded T2 cells, lipid-loaded macrophages, B-1 lymphocytes, and immunoglobulins, clearly demonstrating that ABCG1 has a critical role in pulmonary homeostasis. We identify a variant in the ABCG1 promoter in patients with PAP that results in impaired activation of ABCG1 by the liver X receptor α, suggesting that ABCG1 basal expression and/or induction in response to sterol/lipid loading is essential for normal lung function. We generated mice lacking ABCG1 specifically in either T2 cells or macrophages to determine the relative contribution of these cell types on surfactant lipid homeostasis. These results establish a critical role for T2 cell ABCG1 in controlling surfactant and overall lipid homeostasis in the lung and in the pathogenesis of human lung disease.
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Affiliation(s)
- Thomas Q de Aguiar Vallim
- Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095.,Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095.,Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095.,Johnson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, CA 90095
| | - Elinor Lee
- Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095.,Division of Pulmonary and Critical Care Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - David J Merriott
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | | | - Joan Cheng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - Angela Cheng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - Ayelet Gonen
- Department of Medicine, University of California San Diego, La Jolla, CA 92093
| | - Ryan M Allen
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St. Louis, MO 63104
| | - Elisa N D Palladino
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St. Louis, MO 63104.,Center for Cardiovascular Research, School of Medicine, Saint Louis University, St. Louis, MO 63104
| | - David A Ford
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St. Louis, MO 63104.,Center for Cardiovascular Research, School of Medicine, Saint Louis University, St. Louis, MO 63104
| | - Tisha Wang
- Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095.,Division of Pulmonary and Critical Care Medicine, University of California Los Angeles, Los Angeles, CA 90095
| | - Ángel Baldán
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, St. Louis, MO 63104
| | - Elizabeth J Tarling
- Department of Medicine, University of California Los Angeles, Los Angeles, CA 90095 .,Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095.,Johnson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, CA 90095
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9
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Chai AB, Ammit AJ, Gelissen IC. Examining the role of ABC lipid transporters in pulmonary lipid homeostasis and inflammation. Respir Res 2017; 18:41. [PMID: 28241820 PMCID: PMC5330150 DOI: 10.1186/s12931-017-0526-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/21/2017] [Indexed: 01/03/2023] Open
Abstract
Respiratory diseases including asthma and chronic obstructive pulmonary disease (COPD) are characterised by excessive and persistent inflammation. Current treatments are often inadequate for symptom and disease control, and hence new therapies are warranted. Recent emerging research has implicated dyslipidaemia in pulmonary inflammation. Three ATP-binding cassette (ABC) transporters are found in the mammalian lung – ABCA1, ABCG1 and ABCA3 – that are involved in movement of cholesterol and phospholipids from lung cells. The aim of this review is to corroborate the current evidence for the role of ABC lipid transporters in pulmonary lipid homeostasis and inflammation. Here, we summarise results from murine knockout studies, human diseases associated with ABC transporter mutations, and in vitro studies. Disruption to ABC transporter activity results in lipid accumulation and elevated levels of inflammatory cytokines in lung tissue. Furthermore, these ABC-knockout mice exhibit signs of respiratory distress. ABC lipid transporters appear to have a crucial and protective role in the lung. However, our knowledge of the underlying molecular mechanisms for these benefits requires further attention. Understanding the relationship between cholesterol and inflammation in the lung, and the role that ABC transporters play in this may illuminate new pathways to target for the treatment of inflammatory lung diseases.
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Affiliation(s)
- Amanda B Chai
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, 2006, Australia
| | - Alaina J Ammit
- Woolcock Emphysema Centre, Woolcock Institute of Medical Research, University of Sydney, Camperdown, NSW, Australia. .,School of Life Sciences, University of Technology, Sydney, NSW, Australia.
| | - Ingrid C Gelissen
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, 2006, Australia
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10
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Olmeda B, Martínez-Calle M, Pérez-Gil J. Pulmonary surfactant metabolism in the alveolar airspace: Biogenesis, extracellular conversions, recycling. Ann Anat 2016; 209:78-92. [PMID: 27773772 DOI: 10.1016/j.aanat.2016.09.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/25/2016] [Indexed: 01/03/2023]
Abstract
Pulmonary surfactant is a lipid-protein complex that lines and stabilizes the respiratory interface in the alveoli, allowing for gas exchange during the breathing cycle. At the same time, surfactant constitutes the first line of lung defense against pathogens. This review presents an updated view on the processes involved in biogenesis and intracellular processing of newly synthesized and recycled surfactant components, as well as on the extracellular surfactant transformations before and after the formation of the surface active film at the air-water interface. Special attention is paid to the crucial regulation of surfactant homeostasis, because its disruption is associated with several lung pathologies.
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Affiliation(s)
- Bárbara Olmeda
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Marta Martínez-Calle
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain
| | - Jesus Pérez-Gil
- Department of Biochemistry, Faculty of Biology, and Research Institute "Hospital 12 de Octubre", Complutense University, 28040 Madrid, Spain.
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11
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Ferretti A, Fortwendel JR, Gebb SA, Barrington RA. Autoantibody-Mediated Pulmonary Alveolar Proteinosis in Rasgrp1-Deficient Mice. THE JOURNAL OF IMMUNOLOGY 2016; 197:470-9. [PMID: 27279372 DOI: 10.4049/jimmunol.1502248] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 05/13/2016] [Indexed: 11/19/2022]
Abstract
Pulmonary alveolar proteinosis (PAP) is a rare lung syndrome caused by the accumulation of surfactants in the alveoli. The most prevalent clinical form of PAP is autoimmune PAP (aPAP) whereby IgG autoantibodies neutralize GM-CSF. GM-CSF is a pleiotropic cytokine that promotes the differentiation, survival, and activation of alveolar macrophages, the cells responsible for surfactant degradation. IgG-mediated neutralization of GM-CSF thereby inhibits alveolar macrophage homeostasis and function, leading to surfactant accumulation and innate immunodeficiency. Importantly, there are no rodent models for this disease; therefore, underlying immune mechanisms regulating GM-CSF-specific IgG in aPAP are not well understood. In this article, we identify that autoimmune-prone Rasgrp1-deficient mice develop aPAP: 1) Rasgrp1-deficient mice exhibit reduced pulmonary compliance and lung histopathology characteristic of PAP; 2) alveolar macrophages from Rasgrp1-deficient mice are enlarged and exhibit reduced surfactant degradation; 3) the concentration of GM-CSF-specific IgG is elevated in both serum and bronchoalveolar lavage fluid from Rasgrp1-deficient mice; 4) GM-CSF-specific IgG is capable of neutralizing GM-CSF bioactivity; and 5) Rasgrp1-deficient mice also lacking CD275/ICOSL, a molecule necessary for conventional T cell-dependent Ab production, have reduced GM-CSF-specific autoantibody and do not develop PAP. Collectively, these studies reveal that Rasgrp1-deficient mice, to our knowledge, represent the first rodent model for aPAP.
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Affiliation(s)
- Andrew Ferretti
- Department of Microbiology & Immunology, University of South Alabama, Mobile, AL 36688; Center for Lung Biology, University of South Alabama, Mobile, AL 36688; and
| | - Jarrod R Fortwendel
- Department of Microbiology & Immunology, University of South Alabama, Mobile, AL 36688; Center for Lung Biology, University of South Alabama, Mobile, AL 36688; and
| | - Sarah A Gebb
- Center for Lung Biology, University of South Alabama, Mobile, AL 36688; and Department of Physiology & Cell Biology, University of South Alabama, Mobile, AL 36688
| | - Robert A Barrington
- Department of Microbiology & Immunology, University of South Alabama, Mobile, AL 36688; Center for Lung Biology, University of South Alabama, Mobile, AL 36688; and
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12
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Wei H, Tarling EJ, McMillen TS, Tang C, LeBoeuf RC. ABCG1 regulates mouse adipose tissue macrophage cholesterol levels and ratio of M1 to M2 cells in obesity and caloric restriction. J Lipid Res 2015; 56:2337-47. [PMID: 26489644 DOI: 10.1194/jlr.m063354] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Indexed: 12/27/2022] Open
Abstract
In addition to triacylglycerols, adipocytes contain a large reserve of unesterified cholesterol. During adipocyte lipolysis and cell death seen during severe obesity and weight loss, free fatty acids and cholesterol become available for uptake and processing by adipose tissue macrophages (ATMs). We hypothesize that ATMs become cholesterol enriched and participate in cholesterol clearance from adipose tissue. We previously showed that ABCG1 is robustly upregulated in ATMs taken from obese mice and further enhanced by caloric restriction. Here, we found that ATMs taken from obese and calorie-restricted mice derived from transplantation of WT or Abcg1-deficient bone marrow are cholesterol enriched. ABCG1 levels regulate the ratio of classically activated (M1) to alternatively activated (M2) ATMs and their cellular cholesterol content. Using WT and Abcg1(-/-) cultured macrophages, we found that Abcg1 is most highly expressed by M2 macrophages and that ABCG1 deficiency is sufficient to retard macrophage chemotaxis. However, changes in myeloid expression of Abcg1 did not protect mice from obesity or impaired glucose homeostasis. Overall, ABCG1 modulates ATM cholesterol content in obesity and weight loss regimes leading to an alteration in M1 to M2 ratio that we suggest is due to the extent of macrophage egress from adipose tissue.
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Affiliation(s)
- Hao Wei
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98109-8050 Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA 98109-8050
| | - Elizabeth J Tarling
- Department of Medicine David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095-1737 Department of Biological Chemistry, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA 90095-1737
| | - Timothy S McMillen
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98109-8050 Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA 98109-8050
| | - Chongren Tang
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98109-8050 Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA 98109-8050
| | - Renée C LeBoeuf
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98109-8050 Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA 98109-8050
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Yang MY, Hilton MB, Seaman S, Haines DC, Nagashima K, Burks CM, Tessarollo L, Ivanova PT, Brown HA, Umstead TM, Floros J, Chroneos ZC, St. Croix B. Essential regulation of lung surfactant homeostasis by the orphan G protein-coupled receptor GPR116. Cell Rep 2013; 3:1457-64. [PMID: 23684610 PMCID: PMC3695742 DOI: 10.1016/j.celrep.2013.04.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 04/08/2013] [Accepted: 04/19/2013] [Indexed: 11/22/2022] Open
Abstract
GPR116 is an orphan seven-pass transmembrane receptor whose function has been unclear. Global disruption of the Gpr116 gene in mice revealed an unexpected, critical role for this receptor in lung surfactant homeostasis, resulting in progressive accumulation of surfactant lipids and proteins in the alveolar space, labored breathing, and a reduced lifespan. GPR116 expression analysis, bone marrow transplantation studies, and characterization of conditional knockout mice revealed that GPR116 expression in ATII cells is required for maintaining normal surfactant levels. Aberrant packaging of surfactant proteins with lipids in the Gpr116 mutant mice resulted in compromised surfactant structure, function, uptake, and processing. Thus, GPR116 plays an indispensable role in lung surfactant homeostasis with important ramifications for the understanding and treatment of lung surfactant disorders.
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Affiliation(s)
- Mi Young Yang
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), National Cancer Institute (NCI), NIH, Frederick, MD, 21702, USA
| | - Mary Beth Hilton
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), National Cancer Institute (NCI), NIH, Frederick, MD, 21702, USA
- Basic Research Program, SAIC, Frederick National Laboratory for Cancer Research (FNLCR), NCI, NIH, Frederick, MD 21702, USA
| | - Steven Seaman
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), National Cancer Institute (NCI), NIH, Frederick, MD, 21702, USA
| | - Diana C. Haines
- Veterinary Pathology Section, Pathology/Histotechnology Laboratory, SAIC, FNLCR, NCI, Frederick, MD, 21702, USA
| | - Kunio Nagashima
- Electron Microscopy Laboratory, Advanced Technology Program, SAIC, FNLCR, NCI, Frederick, MD, 21702, USA
| | - Christina M. Burks
- Electron Microscopy Laboratory, Advanced Technology Program, SAIC, FNLCR, NCI, Frederick, MD, 21702, USA
| | - Lino Tessarollo
- Neural Development Section, MCGP, NCI, NIH, Frederick, MD 21702, USA
| | - Pavlina T. Ivanova
- Department of Pharmacology and the Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - H. Alex Brown
- Department of Pharmacology and the Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Todd M. Umstead
- Department of Pediatrics (CHILD), The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, 17033, USA
| | - Joanna Floros
- Department of Pediatrics (CHILD), The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, 17033, USA
- Department of Obstetrics and Gynecology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, 17033, USA
| | - Zissis C. Chroneos
- Department of Pediatrics (CHILD), The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, 17033, USA
| | - Brad St. Croix
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), National Cancer Institute (NCI), NIH, Frederick, MD, 21702, USA
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14
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Abstract
The alveolar type II epithelial (ATII) cell is highly specialised for the synthesis and storage, in intracellular lamellar bodies, of phospholipid destined for secretion as pulmonary surfactant into the alveolus. Regulation of the enzymology of surfactant phospholipid synthesis and metabolism has been extensively characterised at both molecular and functional levels, but understanding of surfactant phospholipid metabolism in vivo in either healthy or, especially, diseased lungs is still relatively poorly understood. This review will integrate recent advances in the enzymology of surfactant phospholipid metabolism with metabolic studies in vivo in both experimental animals and human subjects. It will highlight developments in the application of stable isotope-labelled precursor substrates and mass spectrometry to probe lung phospholipid metabolism in terms of individual molecular lipid species and identify areas where a more comprehensive metabolic model would have considerable potential for direct application to disease states.
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15
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Malur A, Kavuru MS, Marshall I, Barna BP, Huizar I, Karnekar R, Thomassen MJ. Rituximab therapy in pulmonary alveolar proteinosis improves alveolar macrophage lipid homeostasis. Respir Res 2012; 13:46. [PMID: 22697800 PMCID: PMC3432632 DOI: 10.1186/1465-9921-13-46] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 05/16/2012] [Indexed: 11/10/2022] Open
Abstract
RATIONALE Pulmonary Alveolar Proteinosis (PAP) patients exhibit an acquired deficiency of biologically active granulocyte-macrophage colony stimulating factor (GM-CSF) attributable to GM-CSF specific autoantibodies. PAP alveolar macrophages are foamy, lipid-filled cells with impaired surfactant clearance and markedly reduced expression of the transcription factor peroxisome proliferator-activated receptor gamma (PPARγ) and the PPARγ-regulated ATP binding cassette (ABC) lipid transporter, ABCG1. An open label proof of concept Phase II clinical trial was conducted in PAP patients using rituximab, a chimeric murine-human monoclonal antibody directed against B lymphocyte specific antigen CD20. Rituximab treatment decreased anti-GM-CSF antibody levels in bronchoalveolar lavage (BAL) fluid, and 7/9 patients completing the trial demonstrated clinical improvement as measured by arterial blood oxygenation. OBJECTIVES This study sought to determine whether rituximab therapy would restore lipid metabolism in PAP alveolar macrophages. METHODS BAL samples were collected from patients pre- and 6-months post-rituximab infusion for evaluation of mRNA and lipid changes. RESULTS Mean PPARγ and ABCG1 mRNA expression increased 2.8 and 5.3-fold respectively (p ≤ 0.05) after treatment. Lysosomal phospholipase A2 (LPLA2) (a key enzyme in surfactant degradation) mRNA expression was severely deficient in PAP patients pre-treatment but increased 2.8-fold post-treatment. In supplemental animal studies, LPLA2 deficiency was verified in GM-CSF KO mice but was not present in macrophage-specific PPARγ KO mice compared to wild-type controls. Oil Red O intensity of PAP alveolar macrophages decreased after treatment, indicating reduced intracellular lipid while extracellular free cholesterol increased in BAL fluid. Furthermore, total protein and Surfactant protein A were significantly decreased in the BAL fluid post therapy. CONCLUSIONS Reduction in GM-CSF autoantibodies by rituximab therapy improves alveolar macrophage lipid metabolism by increasing lipid transport and surfactant catabolism. Mechanisms may involve GM-CSF stimulation of alveolar macrophage ABCG1 and LPLA2 activities by distinct pathways.
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Affiliation(s)
- Anagha Malur
- Program in Lung Cell Biology and Translational Research, Division of Pulmonary, Critical Care and Sleep Medicine, East Carolina University, Greenville, NC, USA
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