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Little I, Bersie S, Redente EF, McCubbrey AL, Tarling EJ. Alveolar macrophages: guardians of the alveolar lipid galaxy. Curr Opin Lipidol 2025; 36:153-162. [PMID: 40183504 PMCID: PMC12043416 DOI: 10.1097/mol.0000000000000987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/05/2025]
Abstract
PURPOSE OF REVIEW As the primary guardians at the air-surface interface, the functional profile of alveolar macrophages (AM) is wide-ranging from establishment of the alveolar niche, homeostatic maintenance of surfactant levels, to pathogen clearance and resolution and repair processes. Alveolar lipid homeostasis is disturbed in chronic lung diseases and contributes to disease pathogenesis through extracellular localization in the alveolar lumen or intracellular accumulation in AM. This review aims to provide a focused overview of the state of knowledge of AM, their ontogeny and development during health and disease, and how dysregulated AM lipids play a key role in disease processes, from initiation to resolution. RECENT FINDINGS While lipid-laden macrophages are observed across a broad spectrum of lung diseases, their occurrence has largely been considered consequential. Recent advances in lipidomic profiling of single cell types has revealed that disturbances to lipid homeostasis occur early in disease in tissue-resident cells. Comparisons between inflammatory and fibrotic injury models reveal specific alveolar macrophage subsets with different lipid utilization that contribute to the disease process. SUMMARY Understanding the intricate web of AM population seeding and development and how this niche is perturbed by lipid disturbances may help provide leverage for new interventions.
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Affiliation(s)
- Isaiah Little
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, California
| | - Stephanie Bersie
- Toxicology Graduate Program, Skaggs School of Pharmacy and Pharmaceutical Sciences
| | - Elizabeth F. Redente
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Pediatrics
| | - Alexandra L. McCubbrey
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine, National Jewish Health, Denver, Colorado
| | - Elizabeth J. Tarling
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, University of California Los Angeles, Los Angeles, California
- Molecular Biology Institute
- Johnsson Comprehensive Cancer Center (JCCC), University of California Los Angeles, Los Angeles, California, USA
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Hull AJ, Atilano ML, Hallqvist J, Heywood W, Kinghorn KJ. Ceramide lowering rescues respiratory defects in a Drosophila model of acid sphingomyelinase deficiency. Hum Mol Genet 2024; 33:2111-2122. [PMID: 39402882 PMCID: PMC11630749 DOI: 10.1093/hmg/ddae143] [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: 06/02/2024] [Revised: 09/09/2024] [Accepted: 09/25/2024] [Indexed: 12/12/2024] Open
Abstract
Types A and B Niemann-Pick disease (NPD) are inherited multisystem lysosomal storage disorders due to mutations in the SMPD1 gene. Respiratory dysfunction is a key hallmark of NPD, yet the mechanism for this is underexplored. SMPD1 encodes acid sphingomyelinase (ASM), which hydrolyses sphingomyelin to ceramide and phosphocholine. Here, we present a Drosophila model of ASM loss-of-function, lacking the fly orthologue of SMPD1, dASM, modelling several aspects of the respiratory pathology of NPD. dASM is expressed in the late-embryonic fly respiratory network, the trachea, and is secreted into the tracheal lumen. Loss of dASM results in embryonic lethality, and the tracheal lumen fails to fill normally with gas prior to eclosion. We demonstrate that the endocytic clearance of luminal constituents prior to gas-filling is defective in dASM mutants, and is coincident with autophagic, but not lysosomal defects, in late stage embryonic trachea. Finally, we show that although bulk sphingolipids are unchanged, dietary loss of lipids in combination with genetic and pharmacological block of ceramide synthesis rescues the airway gas-filling defects. We highlight myriocin as a potential therapeutic drug for the treatment of the developmental respiratory defects associated with ASM deficiency, and present a new NPD model amenable to genetic and pharmacological screens.
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Affiliation(s)
- Alexander J Hull
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom
| | - Magda L Atilano
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom
| | - Jenny Hallqvist
- Great Ormond Street Institute of Child Health, University College London, 30 Guildford Street, London, WC1N 1EN, United Kingdom
| | - Wendy Heywood
- Great Ormond Street Institute of Child Health, University College London, 30 Guildford Street, London, WC1N 1EN, United Kingdom
| | - Kerri J Kinghorn
- Institute of Healthy Ageing, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom
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Kumar M, Aguiar M, Jessel A, Thurberg BL, Underhill L, Wong H, George K, Davidson V, Schuchman EH. The impact of sphingomyelin on the pathophysiology and treatment response to olipudase alfa in acid sphingomyelinase deficiency. GENETICS IN MEDICINE OPEN 2024; 2:101888. [PMID: 39669638 PMCID: PMC11613795 DOI: 10.1016/j.gimo.2024.101888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 08/04/2024] [Accepted: 08/05/2024] [Indexed: 12/14/2024]
Abstract
Acid sphingomyelinase deficiency (ASMD) is a rare progressive genetic disorder caused by pathogenic variants in the SMPD1 gene causing low or absent activity of the enzyme acid sphingomyelinase, resulting in subsequent accumulation of its substrate, sphingomyelin. Signs and symptoms of excessive lysosomal sphingomyelin storage, such as hepatosplenomegaly and pulmonary impairment, and in a subset of patients, progressive neurological manifestations, have long been recognized as hallmarks of the disease. Uncontrolled accumulation of sphingomyelin has important and complex downstream metabolic and immunologic consequences that contribute to the disease burden. This review article expounds on the complex and multifaceted role of sphingomyelin in the pathophysiology of ASMD and discusses the animal studies and human interventional trials demonstrating that sphingomyelin and its related metabolites are linked to ASMD clinical manifestations, disease burden, and response to treatment. The relationship between the diverse manifestations of ASMD and sphingomyelin accumulation and the connections between sphingomyelin clearance and reversal of the noncentral nervous system manifestations by olipudase alfa therapy also are described.
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Heyndrickx I, Deswarte K, Verstraete K, Verschueren KHG, Smole U, Aegerter H, Dansercoer A, Hammad H, Savvides SN, Lambrecht BN. Ym1 protein crystals promote type 2 immunity. eLife 2024; 12:RP90676. [PMID: 38194250 PMCID: PMC10945506 DOI: 10.7554/elife.90676] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024] Open
Abstract
Spontaneous protein crystallization is a rare event, yet protein crystals are frequently found in eosinophil-rich inflammation. In humans, Charcot-Leyden crystals (CLCs) are made from galectin-10 (Gal10) protein, an abundant protein in eosinophils. Although mice do not encode Gal10 in their genome, they do form pseudo-CLCs, made from the chitinase-like proteins Ym1 and/or Ym2, encoded by Chil3 and Chil4 and made by myeloid and epithelial cells respectively. Here, we investigated the biological effects of pseudo-CLCs since their function is currently unknown. We produced recombinant Ym1 crystals which were shown to have identical crystal packing and structure by X-ray crystallography as in vivo native crystals derived from murine lung. When administered to the airways of mice, crystalline but not soluble Ym1 stimulated innate and adaptive immunity and acted as a type 2 immune adjuvant for eosinophilic inflammation via triggering of dendritic cells (DCs). Murine Ym1 protein crystals found at sites of eosinophilic inflammation reinforce type 2 immunity and could serve as a surrogate model for studying the biology of human CLCs.
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Affiliation(s)
- Ines Heyndrickx
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
| | - Kim Deswarte
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
| | - Kenneth Verstraete
- Unit for Structural Biology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Biochemistry and Microbiology, Ghent UniversityGhentBelgium
| | - Koen HG Verschueren
- Unit for Structural Biology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Biochemistry and Microbiology, Ghent UniversityGhentBelgium
| | - Ursula Smole
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
| | - Helena Aegerter
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
| | - Ann Dansercoer
- Unit for Structural Biology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Biochemistry and Microbiology, Ghent UniversityGhentBelgium
| | - Hamida Hammad
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
| | - Savvas N Savvides
- Unit for Structural Biology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Biochemistry and Microbiology, Ghent UniversityGhentBelgium
| | - Bart N Lambrecht
- Laboratory of Immunoregulation and Mucosal Immunology, VIB-UGent Center for Inflammation ResearchGhentBelgium
- Department of Internal Medicine and Pediatrics, Ghent UniversityGhentBelgium
- Department of Pulmonary Medicine, Erasmus University Medical Center RotterdamRotterdamNetherlands
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Pandey MK. Exploring Pro-Inflammatory Immunological Mediators: Unraveling the Mechanisms of Neuroinflammation in Lysosomal Storage Diseases. Biomedicines 2023; 11:biomedicines11041067. [PMID: 37189685 DOI: 10.3390/biomedicines11041067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023] Open
Abstract
Lysosomal storage diseases are a group of rare and ultra-rare genetic disorders caused by defects in specific genes that result in the accumulation of toxic substances in the lysosome. This excess accumulation of such cellular materials stimulates the activation of immune and neurological cells, leading to neuroinflammation and neurodegeneration in the central and peripheral nervous systems. Examples of lysosomal storage diseases include Gaucher, Fabry, Tay–Sachs, Sandhoff, and Wolman diseases. These diseases are characterized by the accumulation of various substrates, such as glucosylceramide, globotriaosylceramide, ganglioside GM2, sphingomyelin, ceramide, and triglycerides, in the affected cells. The resulting pro-inflammatory environment leads to the generation of pro-inflammatory cytokines, chemokines, growth factors, and several components of complement cascades, which contribute to the progressive neurodegeneration seen in these diseases. In this study, we provide an overview of the genetic defects associated with lysosomal storage diseases and their impact on the induction of neuro-immune inflammation. By understanding the underlying mechanisms behind these diseases, we aim to provide new insights into potential biomarkers and therapeutic targets for monitoring and managing the severity of these diseases. In conclusion, lysosomal storage diseases present a complex challenge for patients and clinicians, but this study offers a comprehensive overview of the impact of these diseases on the central and peripheral nervous systems and provides a foundation for further research into potential treatments.
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Affiliation(s)
- Manoj Kumar Pandey
- Cincinnati Children’s Hospital Medical Center, Division of Human Genetics, Cincinnati, OH 45229-3026, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0515, USA
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Lactose and Galactose Promote the Crystallization of Human Galectin-10. Molecules 2023; 28:molecules28041979. [PMID: 36838965 PMCID: PMC9966682 DOI: 10.3390/molecules28041979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/13/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Galectin-10 (Gal-10) forms Charcot-Leyden crystals (CLCs), which play a key role in the symptoms of asthma and allergies and some other diseases. Gal-10 has a carbohydrate-binding site; however, neither the Gal-10 dimer nor the CLCs can bind sugars. To investigate the monomer-dimer equilibrium of Gal-10, high-performance size-exclusion chromatography (SEC) was employed to separate serial dilutions of Gal-10 with and without carbohydrates. We found that both the dimerization and crystallization of Gal-10 were promoted by lactose/galactose binding. A peak position shift for the monomer was observed after treatment with either lactose or galactose, implying that the polarity of the monomer was reduced by lactose/galactose binding. Further experiments indicated that alkaline conditions of pH 8.8 mimicked the lactose/galactose-binding environment, and the time interval between monomers and dimers in the chromatogram decreased from 0.8 min to 0.4 min. Subsequently, the electrostatic potential of the Gal-10 monomers was computed. After lactose/galactose binding, the top side of the monomer shifted from negatively charged to electrically neutral, allowing it to interact with the carbohydrate-binding site of the opposing subunit during dimerization. Since lactose/galactose promotes the crystallization of Gal-10, our findings implied that dairy-free diets (free of lactose/galactose) might be beneficial to patients with CLC-related diseases.
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