1
|
Zhang Q, Shen X, Yuan X, Huang J, Zhu Y, Zhu T, Zhang T, Wu H, Wu Q, Fan Y, Ni J, Meng L, He A, Shi C, Li H, Hu Q, Wang J, Chang C, Huang F, Li F, Chen M, Liu A, Ye S, Zheng M, Fang H. Lipopolysaccharide binding protein resists hepatic oxidative stress by regulating lipid droplet homeostasis. Nat Commun 2024; 15:3213. [PMID: 38615060 PMCID: PMC11016120 DOI: 10.1038/s41467-024-47553-5] [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: 06/15/2023] [Accepted: 04/02/2024] [Indexed: 04/15/2024] Open
Abstract
Oxidative stress-induced lipid accumulation is mediated by lipid droplets (LDs) homeostasis, which sequester vulnerable unsaturated triglycerides into LDs to prevent further peroxidation. Here we identify the upregulation of lipopolysaccharide-binding protein (LBP) and its trafficking through LDs as a mechanism for modulating LD homeostasis in response to oxidative stress. Our results suggest that LBP induces lipid accumulation by controlling lipid-redox homeostasis through its lipid-capture activity, sorting unsaturated triglycerides into LDs. N-acetyl-L-cysteine treatment reduces LBP-mediated triglycerides accumulation by phospholipid/triglycerides competition and Peroxiredoxin 4, a redox state sensor of LBP that regulates the shuttle of LBP from LDs. Furthermore, chronic stress upregulates LBP expression, leading to insulin resistance and obesity. Our findings contribute to the understanding of the role of LBP in regulating LD homeostasis and against cellular peroxidative injury. These insights could inform the development of redox-based therapies for alleviating oxidative stress-induced metabolic dysfunction.
Collapse
Affiliation(s)
- Qilun Zhang
- Laboratory of Diabetes, Department of Endocrinology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Xuting Shen
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Xin Yuan
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Jing Huang
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Yaling Zhu
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Tengteng Zhu
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Tao Zhang
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Haibo Wu
- Department of Pathology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Qian Wu
- Department of pathology, The First Affiliated Hospital of Anhui University of Chinese Medicine, Hefei, Anhui, 230011, China
| | - Yinguang Fan
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Jing Ni
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, Anhui, 230032, China
| | - Leilei Meng
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Anyuan He
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, 230000, China
| | - Chaowei Shi
- Department of Chemistry, Center for BioAnalytical Chemistry, Hefei National Laboratory of Physical Science at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230022, China
| | - Hao Li
- Department of Chemistry, Center for BioAnalytical Chemistry, Hefei National Laboratory of Physical Science at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230022, China
| | - Qingsong Hu
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of USTC, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, 230001, Hefei, China
| | - Jian Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing, 102206, China
| | - Cheng Chang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing, 102206, China
| | - Fan Huang
- Organ Transplantation Center, Department of General Surgery, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230022, China
| | - Fang Li
- Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230022, China
| | - Meng Chen
- Graduate School of Bengbu Medical College, Bengbu, Anhui, 233030, China
| | - Anding Liu
- Experimental Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, China.
| | - Shandong Ye
- Laboratory of Diabetes, Department of Endocrinology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China.
| | - Mao Zheng
- Laboratory of Diabetes, Department of Endocrinology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China.
| | - Haoshu Fang
- Department of Pathophysiology, Anhui Medical University, Hefei, Anhui, 230000, China.
| |
Collapse
|
2
|
Perrotta I. Interaction between lipid droplets and endoplasmic reticulum in human atherosclerotic plaques. Ultrastruct Pathol 2017; 41:1-9. [DOI: 10.1080/01913123.2016.1269861] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ida Perrotta
- Department of Biology, Ecology and Earth Sciences (Di.B.E.S.T.), Centre for Microscopy and Microanalysis (CM2), Transmission Electron Microscopy Laboratory, University of Calabria, Cosenza, Italy
| |
Collapse
|
3
|
Toledo DAM, D'Avila H, Melo RCN. Host Lipid Bodies as Platforms for Intracellular Survival of Protozoan Parasites. Front Immunol 2016; 7:174. [PMID: 27199996 PMCID: PMC4853369 DOI: 10.3389/fimmu.2016.00174] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 04/19/2016] [Indexed: 12/31/2022] Open
Abstract
Pathogens induce several changes in the host cell signaling and trafficking mechanisms in order to evade and manipulate the immune response. One prominent pathogen-mediated change is the formation of lipid-rich organelles, termed lipid bodies (LBs) or lipid droplets, in the host cell cytoplasm. Protozoan parasites, which contribute expressively to the burden of infectious diseases worldwide, are able to induce LB genesis in non-immune and immune cells, mainly macrophages, key players in the initial resistance to the infection. Under host–parasite interaction, LBs not only accumulate in the host cytoplasm but also relocate around and move into parasitophorous vacuoles. There is increasing evidence that protozoan parasites may target host-derived LBs either for gaining nutrients or for escaping the host immune response. Newly formed, parasite-induced LBs may serve as lipid sources for parasite growth and also produce inflammatory mediators that potentially act in the host immune response deactivation. In this mini review, we summarize current knowledge on the formation and role of host LBs as sites exploited by intracellular protozoan parasites as a strategy to maintain their own survival.
Collapse
Affiliation(s)
- Daniel A M Toledo
- Laboratory of Cellular Biology, Department of Biology, Institute of Biological Sciences (ICB), Federal University of Juiz de Fora (UFJF) , Juiz de Fora, Minas Gerais , Brazil
| | - Heloísa D'Avila
- Laboratory of Cellular Biology, Department of Biology, Institute of Biological Sciences (ICB), Federal University of Juiz de Fora (UFJF) , Juiz de Fora, Minas Gerais , Brazil
| | - Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, Institute of Biological Sciences (ICB), Federal University of Juiz de Fora (UFJF) , Juiz de Fora, Minas Gerais , Brazil
| |
Collapse
|
4
|
Urrutia RA, Kalinec F. Biology and pathobiology of lipid droplets and their potential role in the protection of the organ of Corti. Hear Res 2015; 330:26-38. [PMID: 25987503 PMCID: PMC5391798 DOI: 10.1016/j.heares.2015.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 12/20/2022]
Abstract
The current review article seeks to extend our understanding on the role of lipid droplets within the organ of Corti. In addition to presenting an overview of the current information about the origin, structure and function of lipid droplets we draw inferences from the collective body of knowledge about this cellular organelle to build a conceptual framework to better understanding their role in auditory function. This conceptual model considers that lipid droplets play a significant role in the synthesis, storage, and release of lipids and proteins for energetic use and/or modulating cell signaling pathways. We describe the role and mechanism by which LD play a role in human diseases, and we also review emerging data from our laboratory revealing the potential role of lipid droplets from Hensen cells in the auditory organ. We suggest that lipid droplets might help to develop rapidly and efficiently the resolution phase of inflammatory responses in the mammalian cochlea, preventing inflammatory damage of the delicate inner ear structures and, consequently, sensorineural hearing loss.
Collapse
Affiliation(s)
- Raul A Urrutia
- Epigenetics and Chromatin Dynamics Laboratory, Translational Epigenomic Program, Center for Individualized Medicine (CIM) Mayo Clinic, Rochester, MN 55905, USA
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| |
Collapse
|
5
|
Melo RCN, Weller PF. Lipid droplets in leukocytes: Organelles linked to inflammatory responses. Exp Cell Res 2015; 340:193-7. [PMID: 26515551 DOI: 10.1016/j.yexcr.2015.10.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/23/2015] [Indexed: 01/21/2023]
Abstract
Studies on lipid droplets (LDs) in leukocytes have attracted attention due to their association with human diseases. In these cells, LDs are rapidly formed in response to inflammatory stimuli or allergic/inflammatory diseases including infections with parasites and bacteria. Leukocyte LDs are linked to the regulation of immune responses by compartmentalization of several proteins and lipids involved in the control and biosynthesis of inflammatory mediators (eicosanoids). In this mini review, we summarize current knowledge on the composition, structure and function of leukocyte LDs, organelles now considered as structural markers of inflammation.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, ICB, Federal University of Juiz de Fora, UFJF, Rua José Lourenço Kelmer, Juiz de Fora, MG 36036-900, Brazil; Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 943, Boston, MA 02215, USA.
| | - Peter F Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 943, Boston, MA 02215, USA.
| |
Collapse
|
6
|
Melo RCN, Morgan E, Monahan-Earley R, Dvorak AM, Weller PF. Pre-embedding immunogold labeling to optimize protein localization at subcellular compartments and membrane microdomains of leukocytes. Nat Protoc 2014; 9:2382-94. [PMID: 25211515 DOI: 10.1038/nprot.2014.163] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Precise immunolocalization of proteins within a cell is central to understanding cell processes and functions such as intracellular trafficking and secretion of molecules during immune responses. Here we describe a protocol for ultrastructural detection of proteins in leukocytes. The method uses a pre-embedding approach (immunolabeling before standard processing for transmission electron microscopy (TEM)). This protocol combines several strategies for ultrastructure and antigen preservation, robust blocking of nonspecific binding sites, as well as superior antibody penetration for detecting molecules at subcellular compartments and membrane microdomains. A further advantage of this technique is that electron microscopy (EM) processing is quick. This method has been used to study leukocyte biology, and it has helped demonstrate how activated leukocytes deliver specific cargos. It may also potentially be applied to a variety of different cell types. Excluding the initial time required for sample preparation (15 h) and the final resin polymerization step (16 h), the protocol (immunolabeling and EM procedures) can be completed in 8 h.
Collapse
Affiliation(s)
- Rossana C N Melo
- 1] Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil. [2] Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Ellen Morgan
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Rita Monahan-Earley
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Ann M Dvorak
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter F Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
7
|
Melo RCN, Weller PF. Unraveling the complexity of lipid body organelles in human eosinophils. J Leukoc Biol 2014; 96:703-12. [PMID: 25210147 DOI: 10.1189/jlb.3ru0214-110r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Lipid-rich organelles are common in many cell types. In cells, such as adipocytes, these organelles are termed LDs, whereas in other cells, such as leukocytes, they are called LBs. The study of leukocyte LBs has attracted attention as a result of their association with human diseases. In leukocytes, such as eosinophils, LB accumulation has been documented extensively during inflammatory conditions. In these cells, LBs are linked to the regulation of immune responses by compartmentalization of several proteins and lipids involved in the control and biosynthesis of inflammatory mediators (eicosanoids). However, it has been unclear how diverse proteins, including membrane-associated enzymes involved in eicosanoid formation, incorporate into LBs, especially if the internal content of LBs is assumed to consist solely of stores of neutral lipids, as present within adipocyte LDs. Studies of the formation, function, and ultrastructure of LBs in eosinophils have been providing insights pertinent to LBs in other leukocytes. Here, we review current knowledge of the composition and function of leukocyte LBs as provided by studies of human eosinophil LBs, including recognitions of the internal architecture of eosinophil LBs based on 3D electron tomographic analyses.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil; and Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter F Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
8
|
Dias FF, Zarantonello VC, Parreira GG, Chiarini-Garcia H, Melo RCN. The intriguing ultrastructure of lipid body organelles within activated macrophages. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:869-878. [PMID: 24786359 DOI: 10.1017/s143192761400066x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Macrophages are widely distributed immune system cells with essential functions in tissue homeostasis, apoptotic cell clearance, and first defense in infections. A distinguishing feature of activated macrophages participating in different situations such as inflammatory and metabolic diseases is the presence of increased numbers of lipid-rich organelles, termed lipid bodies (LBs) or lipid droplets, in their cytoplasm. LBs are considered structural markers of activated macrophages and are involved in different functions such as lipid metabolism, intracellular trafficking, and synthesis of inflammatory mediators. In this review, we revisit the distinct morphology of LB organelles actively formed within macrophages in response to infections and cell clearance, taking into account new insights provided by ultrastructural studies. We also discuss the LB interactions within macrophages, revealed by transmission electron microscopy, with a focus on the remarkable LB-phagosome association and discuss potential links between structural aspects and function.
Collapse
Affiliation(s)
- Felipe F Dias
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| | - Victor C Zarantonello
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| | - Gleydes G Parreira
- 2Laboratory of Structural Biology and Reproduction,Federal University of Minas Gerais (UFMG),Belo Horizonte,MG 31270-901,Brazil
| | - Hélio Chiarini-Garcia
- 2Laboratory of Structural Biology and Reproduction,Federal University of Minas Gerais (UFMG),Belo Horizonte,MG 31270-901,Brazil
| | - Rossana C N Melo
- 1Laboratory of Cellular Biology,Department of Biology,Federal University of Juiz de Fora (UFJF),Juiz de Fora,MG 36036-900,Brazil
| |
Collapse
|
9
|
Melo RCN, Paganoti GF, Dvorak AM, Weller PF. The internal architecture of leukocyte lipid body organelles captured by three-dimensional electron microscopy tomography. PLoS One 2013; 8:e59578. [PMID: 23555714 PMCID: PMC3608657 DOI: 10.1371/journal.pone.0059578] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/15/2013] [Indexed: 01/04/2023] Open
Abstract
Lipid bodies (LBs), also known as lipid droplets, are complex organelles of all eukaryotic cells linked to a variety of biological functions as well as to the development of human diseases. In cells from the immune system, such as eosinophils, neutrophils and macrophages, LBs are rapidly formed in the cytoplasm in response to inflammatory and infectious diseases and are sites of synthesis of eicosanoid lipid mediators. However, little is known about the structural organization of these organelles. It is unclear whether leukocyte LBs contain a hydrophobic core of neutral lipids as found in lipid droplets from adipocytes and how diverse proteins, including enzymes involved in eicosanoid formation, incorporate into LBs. Here, leukocyte LB ultrastructure was studied in detail by conventional transmission electron microscopy (TEM), immunogold EM and electron tomography. By careful analysis of the two-dimensional ultrastructure of LBs from human blood eosinophils under different conditions, we identified membranous structures within LBs in both resting and activated cells. Cyclooxygenase, a membrane inserted protein that catalyzes the first step in prostaglandin synthesis, was localized throughout the internum of LBs. We used fully automated dual-axis electron tomography to study the three-dimensional architecture of LBs in high resolution. By tracking 4 nm-thick serial digital sections we found that leukocyte LBs enclose an intricate system of membranes within their “cores”. After computational reconstruction, we showed that these membranes are organized as a network of tubules which resemble the endoplasmic reticulum (ER). Our findings explain how membrane-bound proteins interact and are spatially arranged within LB “cores” and support a model for LB formation by incorporating cytoplasmic membranes of the ER, instead of the conventional view that LBs emerge from the ER leaflets. This is important to understand the functional capabilities of leukocyte LBs in health and during diverse diseases in which these organelles are functionally involved.
Collapse
Affiliation(s)
- Rossana C. N. Melo
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, UFJF, Juiz de Fora, MG, Brazil
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Guillherme F. Paganoti
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, UFJF, Juiz de Fora, MG, Brazil
| | - Ann M. Dvorak
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Peter F. Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
10
|
Melo RCN, Dvorak AM. Lipid body-phagosome interaction in macrophages during infectious diseases: host defense or pathogen survival strategy? PLoS Pathog 2012; 8:e1002729. [PMID: 22792061 PMCID: PMC3390411 DOI: 10.1371/journal.ppat.1002729] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phagocytosis of invading microorganisms by specialized cells such as macrophages and neutrophils is a key component of the innate immune response. These cells capture and engulf pathogens and subsequently destroy them in intracellular vacuoles—the phagosomes. Pathogen phagocytosis and progression and maturation of pathogen-containing phagosomes, a crucial event to acquire microbicidal features, occurs in parallel with accentuated formation of lipid-rich organelles, termed lipid bodies (LBs), or lipid droplets. Experimental and clinical infections with different pathogens such as bacteria, parasites, and viruses induce LB accumulation in cells from the immune system. Within these cells, LBs synthesize and store inflammatory mediators and are considered structural markers of inflammation. In addition to LB accumulation, interaction of these organelles with pathogen-containing phagosomes has increasingly been recognized in response to infections and may have implications in the outcome or survival of the microorganism within host cells. In this review, we summarize our current knowledge on the LB-phagosome interaction within cells from the immune system, with emphasis on macrophages, and discuss the functional meaning of this event during infectious diseases.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, Minas Gerais, Brazil.
| | | |
Collapse
|
11
|
Murphy DJ. The dynamic roles of intracellular lipid droplets: from archaea to mammals. PROTOPLASMA 2012; 249:541-85. [PMID: 22002710 DOI: 10.1007/s00709-011-0329-7] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 09/28/2011] [Indexed: 05/02/2023]
Abstract
During the past decade, there has been a paradigm shift in our understanding of the roles of intracellular lipid droplets (LDs). New genetic, biochemical and imaging technologies have underpinned these advances, which are revealing much new information about these dynamic organelles. This review takes a comparative approach by examining recent work on LDs across the whole range of biological organisms from archaea and bacteria, through yeast and Drosophila to mammals, including humans. LDs probably evolved originally in microorganisms as temporary stores of excess dietary lipid that was surplus to the immediate requirements of membrane formation/turnover. LDs then acquired roles as long-term carbon stores that enabled organisms to survive episodic lack of nutrients. In multicellular organisms, LDs went on to acquire numerous additional roles including cell- and organism-level lipid homeostasis, protein sequestration, membrane trafficking and signalling. Many pathogens of plants and animals subvert their host LD metabolism as part of their infection process. Finally, malfunctions in LDs and associated proteins are implicated in several degenerative diseases of modern humans, among the most serious of which is the increasingly prevalent constellation of pathologies, such as obesity and insulin resistance, which is associated with metabolic syndrome.
Collapse
Affiliation(s)
- Denis J Murphy
- Division of Biological Sciences, University of Glamorgan, Cardiff, CF37 4AT, UK.
| |
Collapse
|
12
|
Bozza PT, Bakker-Abreu I, Navarro-Xavier RA, Bandeira-Melo C. Lipid body function in eicosanoid synthesis: an update. Prostaglandins Leukot Essent Fatty Acids 2011; 85:205-13. [PMID: 21565480 DOI: 10.1016/j.plefa.2011.04.020] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Eicosanoids (prostaglandins, leukotrienes and lipoxins) are signaling lipids derived from arachidonic acid metabolism that have important roles in physiological and pathological processes. Lately, intracellular compartmentalization of eicosanoid-synthetic machinery has emerged as a key component in the regulation of eicosanoid synthesis and functions. Over the past years substantial progresses have been made demonstrating that precursors and enzymes involved in eicosanoid synthesis localize at lipid bodies (also known as lipid droplets) and lipid bodies are distinct sites for eicosanoid generation. Here we will review the current knowledge on the functions of lipid bodies as specialized intracellular sites of compartmentalization of signaling with major roles in eicosanoid formation within cells engaged in inflammatory, infectious and neoplastic process.
Collapse
Affiliation(s)
- Patricia T Bozza
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Brazil.
| | | | | | | |
Collapse
|
13
|
Melo RCN, D'Avila H, Wan HC, Bozza PT, Dvorak AM, Weller PF. Lipid bodies in inflammatory cells: structure, function, and current imaging techniques. J Histochem Cytochem 2011; 59:540-56. [PMID: 21430261 DOI: 10.1369/0022155411404073] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipid bodies (LBs), also known as lipid droplets, have increasingly been recognized as functionally active organelles linked to diverse biological functions and human diseases. These organelles are actively formed in vivo within cells from the immune system, such as macrophages, neutrophils, and eosinophils, in response to different inflammatory conditions and are sites for synthesis and storage of inflammatory mediators. In this review, the authors discuss structural and functional aspects of LBs and current imaging techniques to visualize these organelles in cells engaged in inflammatory processes, including infectious diseases. The dynamic morphological aspects of LBs in leukocytes as inducible, newly formable organelles, elicitable in response to stimuli that lead to cellular activation, contribute to the evolving understanding of LBs as organelles that are critical regulators of different inflammatory diseases, key markers of leukocyte activation, and attractive targets for novel anti-inflammatory therapies.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora (UFJF), Juiz de Fora, MG, Brazil.
| | | | | | | | | | | |
Collapse
|
14
|
Topography of lipid droplet-associated proteins: insights from freeze-fracture replica immunogold labeling. J Lipids 2010; 2011:409371. [PMID: 21490801 PMCID: PMC3068475 DOI: 10.1155/2011/409371] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 11/23/2010] [Indexed: 11/18/2022] Open
Abstract
Lipid droplets are not merely storage depots for superfluous intracellular lipids in times of hyperlipidemic stress, but metabolically active organelles involved in cellular homeostasis. Our concepts on the metabolic functions of lipid droplets have come from studies on lipid droplet-associated proteins. This realization has made the study of proteins, such as PAT family proteins, caveolins, and several others that are targeted to lipid droplets, an intriguing and rapidly developing area of intensive inquiry. Our existing understanding of the structure, protein organization, and biogenesis of the lipid droplet has relied heavily on microscopical techniques that lack resolution and the ability to preserve native cellular and protein composition. Freeze-fracture replica immunogold labeling overcomes these disadvantages and can be used to define at high resolution the precise location of lipid droplet-associated proteins. In this paper illustrative examples of how freeze-fracture immunocytochemistry has contributed to our understanding of the spatial organization in the membrane plane and function of PAT family proteins and caveolin-1 are presented. By revisiting the lipid droplet with freeze-fracture immunocytochemistry, new perspectives have emerged which challenge prevailing concepts of lipid droplet biology and may hopefully provide a timely impulse for many ongoing studies.
Collapse
|
15
|
Abstract
Accumulation of lipid droplets (also known as lipid bodies or adiposomes) within leukocytes, epithelial cells, hepatocytes and other non-adipocytic cells is a frequently observed phenotype in infectious, neoplastic and other inflammatory conditions. Lipid droplet biogenesis is a regulated cellular process that culminates in the compartmentalization of lipids and of an array of enzymes, protein kinases and other proteins, suggesting that lipid droplets are inducible organelles with roles in cell signaling, regulation of lipid metabolism, membrane trafficking and control of the synthesis and secretion of inflammatory mediators. Enzymes involved in eicosanoid synthesis are localized at lipid droplets and lipid droplets are sites for eicosanoid generation in cells during inflammation and cancer. In this review, we discuss the current evidence related to the biogenesis and function of lipid droplets in cell metabolism and signaling in inflammation and cancer. Moreover, the potential of lipid droplets as markers of disease and targets for novel anti-inflammatory and antineoplastic therapies will be discussed.
Collapse
Affiliation(s)
- Patricia T Bozza
- Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
| | | |
Collapse
|
16
|
den Hartigh LJ, Connolly-Rohrbach JE, Fore S, Huser TR, Rutledge JC. Fatty acids from very low-density lipoprotein lipolysis products induce lipid droplet accumulation in human monocytes. THE JOURNAL OF IMMUNOLOGY 2010; 184:3927-36. [PMID: 20208007 DOI: 10.4049/jimmunol.0903475] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
One mechanism by which monocytes become activated postprandially is by exposure to triglyceride-rich lipoproteins such as very low-density lipoproteins (VLDL). VLDL are hydrolyzed by lipoprotein lipase at the blood-endothelial cell interface, releasing free fatty acids. In this study, we examined postprandial monocyte activation in more detail, and found that lipolysis products generated from postprandial VLDL induce the formation of lipid-filled droplets within cultured THP-1 monocytes, characterized by coherent antistokes Raman spectroscopy. Organelle-specific stains revealed an association of lipid droplets with the endoplasmic reticulum, confirmed by electron microscopy. Lipid droplet formation was reduced when lipoprotein lipase-released fatty acids were bound by BSA, which also reduced cellular inflammation. Furthermore, saturated fatty acids induced more lipid droplet formation in monocytes compared with mono- and polyunsaturated fatty acids. Monocytes treated with postprandial VLDL lipolysis products contained lipid droplets with more intense saturated Raman spectroscopic signals than monocytes treated with fasting VLDL lipolysis products. In addition, we found that human monocytes isolated during the peak postprandial period contain more lipid droplets compared with those from the fasting state, signifying that their development is not limited to cultured cells but also occurs in vivo. In summary, circulating free fatty acids can mediate lipid droplet formation in monocytes and potentially be used as a biomarker to assess an individual's risk of developing atherosclerotic cardiovascular disease.
Collapse
Affiliation(s)
- Laura J den Hartigh
- Division of Endocrinology, Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | | | | | | | | |
Collapse
|
17
|
Bozza PT, D’Avila H, Almeida PE, Magalhães KG, Molinaro R, Almeida CJ, Maya-Monteiro CM. Lipid droplets in host–pathogen interactions. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/clp.09.63] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
18
|
Goodman JM. Demonstrated and inferred metabolism associated with cytosolic lipid droplets. J Lipid Res 2009; 50:2148-56. [PMID: 19696439 DOI: 10.1194/jlr.r001446] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cytosolic lipid droplets were considered until recently to be rather inert particles of stored neutral lipid. Largely through proteomics is it now known that droplets are dynamic organelles and that they participate in several important metabolic reactions as well as trafficking and interorganellar communication. In this review, the role of droplets in metabolism in the yeast Saccharomyces cerevisiae, the fly Drosophila melanogaster, and several mammalian sources are discussed, particularly focusing on those reactions shared by these organisms. From proteomics and older work, it is clear that droplets are important for fatty acid and sterol biosynthesis, fatty acid activation, and lipolysis. However, many droplet-associated enzymes are predicted to span a membrane two or more times, which suggests either that droplet structure is more complex than the current model posits, or that there are tightly bound membranes, particularly derived from the endoplasmic reticulum, which account for the association of several of these proteins.
Collapse
Affiliation(s)
- Joel M Goodman
- Department of Pharmacology University of Texas Southwestern Medical School Dallas TX 75390-9041, USA.
| |
Collapse
|
19
|
Melo RCN. Acute heart inflammation: ultrastructural and functional aspects of macrophages elicited by Trypanosoma cruzi infection. J Cell Mol Med 2009; 13:279-94. [PMID: 18624767 PMCID: PMC3823355 DOI: 10.1111/j.1582-4934.2008.00388.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 05/24/2008] [Indexed: 01/08/2023] Open
Abstract
The heart is the main target organ of the parasite Trypanosoma cruzi, the causal agent of Chagas' disease, a significant public health issue and still a major cause of morbidity and mortality in Latin America. During the acute disease, tissue damage in the heart is related to the intense myocardium parasitism. To control parasite multiplication, cells of the monocytic lineage are highly mobilized. In response to inflammatory and immune stimulation, an intense migration and extravasation of monocytes occurs from the bloodstream into heart. Monocyte differentiation leads to the formation of tissue phagocytosing macrophages, which are strongly activated and direct host defence. Newly elicited monocyte-derived macrophages both undergo profound physiological changes and display morphological heterogeneity that greatly differs from originally non-inflammatory macrophages, and underlie their functional activities as potent inflammatory cells. Thus, activated macrophages play a critical role in the outcome of parasite infection. This review covers functional and ultrastructural aspects of heart inflammatory macrophages triggered by the acute Chagas' disease, including recent discoveries on morphologically distinct, inflammation-related organelles, termed lipid bodies, which are actively formed in vivo within macrophages in response to T. cruzi infection. These findings are defining a broader role for lipid bodies as key markers of macrophage activation during innate immune responses to infectious diseases and attractive targets for novel anti-inflammatory therapies. Modulation of macrophage activation may be central in providing therapeutic benefits for Chagas' disease control.
Collapse
Affiliation(s)
- Rossana C N Melo
- Department of Biology, Federal University of Juiz de Fora, MG, Brazil.
| |
Collapse
|
20
|
Bozza PT, Magalhães KG, Weller PF. Leukocyte lipid bodies - Biogenesis and functions in inflammation. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:540-51. [PMID: 19416659 DOI: 10.1016/j.bbalip.2009.01.005] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 01/06/2009] [Accepted: 01/09/2009] [Indexed: 12/19/2022]
Abstract
Lipid body accumulation within leukocytes is a common feature in both clinical and experimental infectious, neoplasic and other inflammatory conditions. Here, we will review the contemporary evidence related to the biogenesis and structure of leukocyte lipid bodies (also known as lipid droplets) as inflammatory organelles. Studies of leukocyte lipid bodies are providing functional, ultrastructural and protein compositional evidences that lipid bodies are not solely storage depots of neutral lipid. Over the past years substantial progresses have been made to demonstrate that lipid body biogenesis is a highly regulated process, that culminate in the compartmentalization of a specific set of proteins and lipids, that place leukocyte lipid bodies as inducible cytoplasmic organelles with roles in cell signaling and activation, regulation of lipid metabolism, membrane trafficking and control of the synthesis and secretion of inflammatory mediators. Pertinent to the roles of lipid bodies in inflammation and cell signaling, enzymes involved in eicosanoid synthesis are localized at lipid bodies and lipid bodies are sites for eicosanoid generation. Collectively, lipid bodies in leukocytes are emerging as critical regulators of different inflammatory diseases, key markers of leukocyte activation and attractive targets for novel anti-inflammatory therapies.
Collapse
Affiliation(s)
- Patricia T Bozza
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, 4365, Manguinhos, 21045-900, Rio de Janeiro, RJ, Brazil.
| | | | | |
Collapse
|
21
|
Robenek H, Buers I, Hofnagel O, Robenek MJ, Troyer D, Severs NJ. Compartmentalization of proteins in lipid droplet biogenesis. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:408-18. [PMID: 19118639 DOI: 10.1016/j.bbalip.2008.12.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 12/03/2008] [Accepted: 12/03/2008] [Indexed: 10/21/2022]
Abstract
Our existing understanding of the structure, protein organization and biogenesis of the lipid droplet has relied heavily on microscopical techniques that lack resolution and the ability to preserve native cellular and protein composition. The electron microscopic technique of freeze-fracture replica immunogold labeling (FRIL) overcomes these problems, and is currently providing new perspectives in the field. Because of the property of frozen lipids to deflect the fracture plane, en face views of the lipid droplet and its component layers are revealed for high resolution visualization. By means of immunogold labeling, proteins involved in the accretion and mobilization of lipids, notably the PAT family proteins, can be localized at and in the droplet. Application of this approach demonstrates that, contrary to prevailing wisdom, the PAT family proteins are not invariably restricted to the surface of the lipid droplet but can occur throughout the core. The notion that lipid droplet biogenesis involves neutral lipid accumulation within the ER membrane bilayer followed by budding off, enclosed by a protein-containing phospholipid monolayer, is not substantiated. Instead, lipid droplets appear to develop externally to both ER membranes at specialized sites in which the ER enwraps the droplet, and the facing leaflets of the ER membrane and droplet surface are enriched in adipophilin. PAT family proteins are not, as often stated, specific to the lipid droplet, but are widely present in the plasma membrane where, under conditions of lipid loading, they adopt a similar configuration to that of specialized sites in the ER. FRIL has further provided new insights into the mechanism of secretion of a special type of lipid droplet, the milk fat globule. These examples highlight the contribution of the FRIL technique to critical appraisal and development of concepts in the lipid droplet field.
Collapse
Affiliation(s)
- Horst Robenek
- Department of Cell Biology and Ultrastructure Research, Leibniz Institute for Arteriosclerosis Research, University of Münster, Germany.
| | | | | | | | | | | |
Collapse
|
22
|
Guruswamy S, Rao CV. Multi-Target Approaches in Colon Cancer Chemoprevention Based on Systems Biology of Tumor Cell-Signaling. GENE REGULATION AND SYSTEMS BIOLOGY 2008; 2:163-176. [PMID: 19763245 PMCID: PMC2745153 DOI: 10.4137/grsb.s486] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Colorectal cancer is the leading cause of cancer related deaths in the United States. Although it is preventable, thousands of lives are lost each year in the U.S. to colorectal cancer than to breast cancer and AIDS combined. In colon cancer, the formation and progression of precancerous lesions like aberrant crypt foci and polyps is associated with the up-regulation of cycloxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and hydroxy methyl glutaryl CoA reductase (HMG-CoA reductase). The current review will focus on the signaling pathway involving COX-2 and HMG-CoA reductase enzymes and their downstream effectors in signaling mechanism. Cancer cells need huge pools of both cholesterol and isoprenoids to sustain their unlimited growth potential. Cholesterol by modulating caveolae formation regulates several signaling molecules like AKT, IGFR, EGFR and Rho which are involved in cell growth and survival. Cholesterol is also essential for lipid body formation which serves as storage sites for COX-2, eicosanoids and caveolin-1. Experimental studies have identified important mechanisms showing that COX-2, caveolin-1, lipid bodies and prenylated proteins is involved in carcinogenesis. Therefore multi-target, multi-drug approach is the ideal choice for effective colon cancer chemoprevention. This review will give an overview of the two pathways, their signaling networks, and the interactions between the components of the two networks in the activation and regulation of cell signaling involving growth/survival and explain the rationale for colon cancer chemoprevention using COX-2 inhibitors and statins.
Collapse
Affiliation(s)
- Suresh Guruswamy
- Department of Medicine, Hematology-Oncology Section, University of Oklahoma Health Sciences Center, Oklahoma City, OK, U.S.A
| | | |
Collapse
|
23
|
Lotfi R, Lee JJ, Lotze MT. Eosinophilic granulocytes and damage-associated molecular pattern molecules (DAMPs): role in the inflammatory response within tumors. J Immunother 2007; 30:16-28. [PMID: 17198080 DOI: 10.1097/01.cji.0000211324.53396.f6] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The development of a tumor over many years typically leads to reciprocal alternations in the host and the tumor, enabling tumor growth paradoxically in the setting of substantial necrosis and inflammation. When evaluating a tumor, it is important to assess 3 elements: (1) the quantity and quality of tumor-associated leukocytes, (2) their state of activation, and (3) tumor microenvironment. Peripheral blood eosinophilia and tumor-associated tissue eosinophilia are frequently associated with some tumor types and also found after immunotherapy with IL-2, IL-4, granulocyte-macrophage colony-stimulating factor, and antibody to CTLA-4. Within several tumor types including gastrointestinal tumors, tumor-associated tissue eosinophilia is associated with a significantly better prognosis. The converse is true in other tumor types such as differentiated oral squamous cell carcinoma. On the basis of the emergent data, tumor-associated eosinophils have at least 2 dominant nonoverlapping activities: (1) destructive effector functions potentially limiting tumor growth as well as causing recruitment and activation of other leukocytes, (2) immunoregulative and remodeling activities which suppress immune response and promote tumor proliferation. The mechanism by which eosinophils in particular are recruited into tumor tissue is largely unknown. Candidates for causing eosinophil chemotaxis into tumor tissue are the released damage-associated molecular pattern molecules (DAMPs) including the nuclear protein high mobility group box 1. High mobility group box 1 is released upon necrotic cell death and secreted by many cells, particularly during periods of nutrient, hypoxic, or oxidant stress. This overview on eosinophil biology in the context of cancer and necrosis, introduces intriguing and novel strategies targeting eosinophils to enable more effective biologic therapy for cancer patients.
Collapse
Affiliation(s)
- Ramin Lotfi
- University of Pittsburgh, Hillmann Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA
| | | | | |
Collapse
|
24
|
Wan HC, Melo RCN, Jin Z, Dvorak AM, Weller PF. Roles and origins of leukocyte lipid bodies: proteomic and ultrastructural studies. FASEB J 2006; 21:167-78. [PMID: 17135363 PMCID: PMC2715426 DOI: 10.1096/fj.06-6711com] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Lipid bodies (LBs), multifunctional organelles present in most eukaryotic cells, are sites of eicosanoid formation in leukocytes; but little is known about the composition of leukocyte LBs or the biogenesis and internal structures of LBs from mammalian cells. Proteomic analyses of LBs purified from human monocytic U937 cells detected, common to LBs in other cells, proteins involved in cholesterol and triglyceride metabolism, Rab GTPases, and many membrane and endoplasmic reticulum (ER)-associated proteins. Newly lipid body (LB)-associated proteins included MRP-14, potentially involved in arachidonate transport, and ribosomal subunit proteins and translation regulatory proteins. Ultrastructurally, in U937 cells as well as human neutrophils and eosinophils, ribosomes are attached to and distributed within LBs, and LBs contain extensive ER-like membranes. The presence of ribosomes, ER-like membranes and many membrane-associated and ER luminal proteins within LBs, supports a new model by which enveloped ER-membranes and domains form LBs and indicates that LBs may be sites of protein synthesis.
Collapse
Affiliation(s)
- Hsiao-Ching Wan
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Rossana C. N. Melo
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
- Department of Biology, Federal University of Juiz de Fora, UFJF, Juiz de Fora, MG, Brazil
| | - Zhoung Jin
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Ann M. Dvorak
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter F. Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
- Correspondence: Beth Israel Deaconess Medical Center, DA-617, 330 Brookline Ave., Boston, MA 02215, USA. E-mail:
| |
Collapse
|
25
|
Bozza PT, Melo RCN, Bandeira-Melo C. Leukocyte lipid bodies regulation and function: contribution to allergy and host defense. Pharmacol Ther 2006; 113:30-49. [PMID: 16945418 DOI: 10.1016/j.pharmthera.2006.06.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 06/20/2006] [Indexed: 12/21/2022]
Abstract
Lipid bodies are lipid-rich organelles found in the cytoplasm of a variety of cells, including leukocytes. Lipid body morphology, its ability to interact with other organelles and its functions are dictated by its lipid arrangement, as well as its protein composition. Both may vary according to the cell type and with the specific lipid body biogenic stimulatory pathways. Nascent lipid bodies, which are formed in vivo in the course of a variety of immunopathological conditions, are sites of enzyme localization, eicosanoid production, as well as, sites for cytokine storage in inflammatory leukocytes, suggesting that lipid bodies function as inducible intracellular platforms for spatial segregation and organization of signaling leading to inflammatory mediator secretion during inflammation. The emerging role of lipid bodies as inflammatory organelles raises lipid body status to critical regulators of different inflammatory diseases, key markers of leukocyte activation and attractive targets for novel anti-inflammatory therapies.
Collapse
Affiliation(s)
- Patricia T Bozza
- Laboratório de Imunofarmacologia, Departamento de Fisiologia e Farmacodinâmica, IOC, Fundação Oswaldo Cruz, Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21045-900, Brazil.
| | | | | |
Collapse
|
26
|
Melo RCN, Sabban A, Weller PF. Leukocyte lipid bodies: inflammation-related organelles are rapidly detected by wet scanning electron microscopy. J Lipid Res 2006; 47:2589-94. [PMID: 16940552 DOI: 10.1194/jlr.d600028-jlr200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leukocyte lipid bodies are dynamic, functionally active organelles with central roles in inflammation. Here, we report that leukocyte lipid bodies are facilely detected by a versatile, potent technique, termed wet scanning electron microscopy (SEM), which combines the rapid preparation of light microscopy with the resolution of SEM. Using as leukocyte models resting and agonist-stimulated human eosinophils, cells that generate prominent numbers of lipid bodies in inflammatory conditions, we demonstrated that lipid bodies can be rapidly imaged as bright, highly contrasted structures under wet SEM and scored by computerized image processing. Critical advantages of this approach are that it permits cell observation in a fully hydrated system and facilitates lipid preservation. These attributes are especially important because lipid bodies are degraded during routine dehydration processes. Moreover, this technology is advantageous over lipophilic fluorescent probes because it allows sustained detection of lipid bodies in contrast to short-lived fluorescent labeling of these organelles. The value of wet SEM in enabling rapid and large-scale lipid body imaging and scoring within leukocytes is particularly important because lipid bodies are organelles underlying the heightened functions of inflammatory cells. Wet SEM technology provides new approaches and opportunities for delineations of lipid bodies in inflammatory diseases, including allergic inflammation.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | | | | |
Collapse
|
27
|
Abstract
Human eosinophils have been demonstrated to contain a multitude of cytokines and chemokines that exist pre-formed within these cells. This content of pre-formed cytokines, with diverse potential biologic activities, provides eosinophils with capabilities distinct from most other leukocytes. The localization of pre-formed cytokines within eosinophils is both within specific granules and associated with substantial numbers of morphologically distinct cytoplasmic vesicles. Stimulation for release of specific cytokines, such as IL-4, leads to a regulated signal transduction cascade, which is dependent on the formation of leukotriene C4 within eosinophils where it acts as an intracrine mediator. IL-4 release occurs selectively and is by means of vesicular transport. The capabilities of eosinophils not only to rapidly release pre-formed cytokines but also to differentially regulate which cytokines are released endow eosinophils with distinct abilities in innate and acquired immunity.
Collapse
Affiliation(s)
- Christianne Bandeira-Melo
- Laboratório de Imunofarmacologia, Departamento de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil
| | - Peter F Weller
- Laboratório de Imunofarmacologia, Departamento de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro, RJ, Brasil
- Department of Medicine, Harvard Thorndike Laboratories, Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, DA - 617, 330 Brooklyne Avenue, Harvard Medical School, Boston, MA, 02215, US
- Corresponding author. E-mail:
| |
Collapse
|
28
|
Abstract
The PAT family proteins, named after perilipin, adipophilin, and the tail-interacting protein of 47 kDa (TIP47), are implicated in intracellular lipid metabolism. They associate with lipid droplets, but how is completely unclear. From immunofluorescence studies, they are reported to be restricted to the outer membrane monolayer enveloping the lipid droplet and not to enter the core. Recently, we found another kind of lipid droplet-associated protein, caveolin-1, inside lipid droplets. Using freeze-fracture immunocytochemistry and electron microscopy, we now describe the distributions of perilipin and caveolin-1 and of adipophilin and TIP47 in lipid droplets of adipocytes and macrophages. All of these lipid droplet-associated proteins pervade the lipid droplet core and hence are not restricted to the droplet surface. Moreover, lipid droplets are surprisingly heterogeneous with respect to their complements and their distribution of lipid droplet-associated proteins. Whereas caveolin-1 is synthesized in the endoplasmic reticulum and is transferred to the lipid droplet core by inundating lipids during droplet budding, the PAT proteins, which are synthesized on free ribosomes in the cytoplasm, evidently target to the lipid droplet after it has formed. How the polar lipid droplet-associated proteins are accommodated among the essentially hydrophobic neutral lipids of the lipid droplet core remains to be determined.
Collapse
Affiliation(s)
- Horst Robenek
- Institute for Arteriosclerosis Research, University of Münster, Münster, Germany.
| | | | | |
Collapse
|
29
|
Robenek H, Robenek MJ, Buers I, Lorkowski S, Hofnagel O, Troyer D, Severs NJ. Lipid droplets gain PAT family proteins by interaction with specialized plasma membrane domains. J Biol Chem 2005; 280:26330-8. [PMID: 15897193 DOI: 10.1074/jbc.m413312200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteins of the PAT family, named after perilipin, adipophilin, and TIP47 (tail-interacting protein of 47 kDa), are associated with lipid droplets and have previously been localized by immunofluorescence microscopy exclusively to the droplet surface. These proteins are considered not to be present in any other subcellular compartment. By applying the high resolution technique of freeze-fracture electron microscopy combined with immunogold labeling, we now demonstrate that in macrophages and adipocytes PAT family proteins are, first, distributed not only in the surface but also throughout the lipid droplet core and, second, are integral components of the plasma membrane. Under normal culture conditions these proteins are dispersed in the cytoplasmic leaflet of the plasma membrane. Stimulation of lipid droplet formation by incubation of the cells with acetylated low density lipoprotein leads to clustering of the PAT family proteins in raised plasma membrane domains. Fractures penetrating beneath the plasma membrane demonstrate that lipid droplets are closely apposed to these domains. A similar distribution pattern of labeling in the form of linear aggregates within the clusters is apparent in the cytoplasmic monolayer of the plasma membrane and the immediately adjacent outer monolayer of the lipid droplet. The aggregation of the PAT family proteins into such assemblies may facilitate carrier-mediated lipid influx from the extracellular environment into the lipid droplet. Lipid droplets appear to acquire their PAT proteins by interaction with plasma membrane domains enriched in these proteins.
Collapse
Affiliation(s)
- Horst Robenek
- Department of Cell Biology and Ultrastructure Research, Leibniz-Institute for Arteriosclerosis Research, University of Münster, Münster, Germany.
| | | | | | | | | | | | | |
Collapse
|
30
|
Robenek H, Lorkowski S, Schnoor M, Troyer D. Spatial integration of TIP47 and adipophilin in macrophage lipid bodies. J Biol Chem 2004; 280:5789-94. [PMID: 15545278 DOI: 10.1074/jbc.m407194200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We studied the distribution of the PAT family proteins TIP47 and adipophilin in lipid bodies of THP-1 cell-derived macrophages using freeze-fracture immunolabeling and other techniques. Lipid bodies in macrophages comprise lipid droplets and extensive, previously scantily characterized sheet-like organelles, which we descriptively call "lipid sails." TIP47 and adipophilin are components of many, but not all, the lipid droplets. Both proteins are not confined to the surface of lipid droplets, as supposed, but are also inside lipid droplet cores. They are not codistributed stoichiometrically in lipid droplets. How TIP47 and adipophilin, which are polar proteins, enter the lipid droplets and are packaged among the hydrophobic neutral lipids of the core is unclear. However, in the lipid layers of the core, these proteins are directed sometimes inward and sometimes outward. Because TIP47 and adipophilin also localize to lipid sails, lipid sails are intimately involved in intracellular lipid metabolism.
Collapse
Affiliation(s)
- Horst Robenek
- Institute for Arteriosclerosis Research, University of Münster, Domagkstrasse 3, 48149 Münster, Germany.
| | | | | | | |
Collapse
|
31
|
Arend A, Masso R, Masso M, Selstam G. Electron microscope immunocytochemical localization of cyclooxygenase-1 and -2 in pseudopregnant rat corpus luteum during luteolysis. Prostaglandins Other Lipid Mediat 2004; 74:1-10. [PMID: 15560112 DOI: 10.1016/j.prostaglandins.2004.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Prostaglandins converted from arachidonic acid by cyclooxygenases play an important regulatory role in regression of the corpus luteum. To reveal luteal distribution of cyclooxygenase isoforms during luteolysis, an electron microscope immunocytochemical study was performed. Cyclooxygenase-1 and -2 were found both in luteal steroid-producing and interstitial cells on days 13, 15 and 18 of the adult pseudopregnant rat. Cyclooxygenase-2 immunolabelling was predominantly seen in non-luteal cells. The two enzymes were localized in similar fashion to the plasma membrane, rough and smooth endoplasmic reticulum, lipid bodies and mitochondria, but differently in the nuclear compartment. Cyclooxygenase-1 labelling was found only in the perinuclear region, while cyclooxygenase-2 was localized to the nuclear envelope, region of condensed heterochromatin as well as at the perimeter of the heterochromatin. Nuclear residence may indicate additional roles for cyclooxygenase-2 in regulating gene expression. Identification of both enzymes on lipid bodies suggests that these inclusions may be involved in luteal prostanoid production.
Collapse
Affiliation(s)
- Andres Arend
- Department of Anatomy, University of Tartu, Biomedicum, Ravila 19, Tartu 50411, Estonia.
| | | | | | | |
Collapse
|
32
|
Luo M, Jones SM, Peters-Golden M, Brock TG. Nuclear localization of 5-lipoxygenase as a determinant of leukotriene B4 synthetic capacity. Proc Natl Acad Sci U S A 2003; 100:12165-70. [PMID: 14530386 PMCID: PMC218730 DOI: 10.1073/pnas.2133253100] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The enzyme 5-lipoxygenase (5-LO) initiates the synthesis of leukotrienes from arachidonic acid. In resting cells, 5-LO can accumulate in either the cytoplasm or the nucleoplasm and, upon cell stimulation, translocates to membranes to initiate leukotriene synthesis. Here, we used mutants of 5-LO with altered subcellular localization to assess the role that nuclear positioning plays in determining leukotriene B4 (LTB4) synthesis. Mutation of either a nuclear localization sequence or a phosphorylation site reduced LTB4 synthesis by 60%, in parallel with reduced nuclear localization of 5-LO. Mutation of both sites together or mutation of all three nuclear localization sequences on 5-LO inhibited LTB4 synthesis by 90% and abolished nuclear localization. Reduced LTB4 generation in mutants could not be attributed to differences in 5-LO amount, enzymatic activity, or membrane association. Instead, 5-LO within the nucleus acts at a different site, the nuclear envelope, than does cytosolic 5-LO, which acts at cytoplasmic and perinuclear membranes. The significance of this difference was suggested by evidence that exogenously derived arachidonic acid colocalized with activated nuclear 5-LO. These results unequivocally demonstrate that the positioning of 5-LO within the nucleus of resting cells is a powerful determinant of the capacity to generate LTB4 upon subsequent activation.
Collapse
Affiliation(s)
- Ming Luo
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | | | |
Collapse
|
33
|
Abstract
Eosinophils are the main source of the cysteinyl leukotrienes, LTC(4)/D(4)/E(4), which are lipid mediators that play major roles in the pathogenesis of asthma and other forms of allergic inflammation. Here, we review the mechanisms governing eosinophil LTC(4) synthesis, focusing on the distinct intracellular domains that regulate eicosanoid formation and function within eosinophils. Cysteinyl leukotrienes exert their actions by engaging specific receptors. As recently shown, eosinophils express CysLT1 and CysLT2, the only cloned receptors for cysteinyl leukotrienes. Therefore, here we also present some of the new findings regarding the paracrine/autocrine activation of these CysLT receptors on eosinophils, and discuss some data on novel intracrine effects of LTC(4) triggered by a putative third CysLT receptor expressed intracellularly within eosinophils.
Collapse
Affiliation(s)
- Christianne Bandeira-Melo
- Department of Medicine, Charles A Dana Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
| | | |
Collapse
|
34
|
Melo RCN, D'Avila H, Fabrino DL, Almeida PE, Bozza PT. Macrophage lipid body induction by Chagas disease in vivo: putative intracellular domains for eicosanoid formation during infection. Tissue Cell 2003; 35:59-67. [PMID: 12589730 DOI: 10.1016/s0040-8166(02)00105-2] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Lipid bodies (LB), lipid-rich inclusions abundantly present in cells engaged in inflammation, are specialized intracellular domains involved in generating inflammatory mediators, the eicosanoids. Since the acute Trypanosoma cruzi infection triggers a potent inflammatory reaction characterized by a great increase of peripheral blood monocyte (PBM) and macrophage numbers, we investigated the LB occurrence in these cells. The experimental rat infection by T. cruzi (Y strain) induced significant increase of the LB numbers in peritoneal macrophages at day 6 and 12, accompanied by significant enhancement of Prostaglandin E(2) (PGE(2)) production, as measured by EIA. At day 12, ultrastructural analysis of the heart, a target organ of the disease, showed numerous macrophages with LB prominently increased in number (mean of 8.3 per section view, range of 1-25) compared to controls (mean of 2.6 per section view, range of 0-3) and size. PBM from all groups rarely showed LB. Our results demonstrate, for the first time, that T. cruzi infection in rats elicits important LB formation in inflammatory macrophages but not in PBM. The increase in LB numbers during infection positively correlates with increased generation of PGE(2), suggesting that LB may have a role in the heightened eicosanoid production observed during T. cruzi infection.
Collapse
Affiliation(s)
- R C N Melo
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, 36036-330, Juiz de Fora, MG, Brazil.
| | | | | | | | | |
Collapse
|
35
|
Bozza PT, Pacheco P, Yu W, Weller PF. NS-398: cyclooxygenase-2 independent inhibition of leukocyte priming for lipid body formation and enhanced leukotriene generation. Prostaglandins Leukot Essent Fatty Acids 2002; 67:237-44. [PMID: 12401438 DOI: 10.1054/plef.2002.0425] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Because the induction of new lipid body formation in leukocytes correlates with and likely contributes to their enhanced 'primed' prostaglandin and leukotriene formation, we evaluated two selective cyclooxygenase (COX)-2 inhibitors. Three types of stimuli, cis -unsaturated fatty acids, platelet activating factor and protein kinase C activators, stimulate lipid body formation. NS-398 (0.1-10 microM), but not another COX-2 inhibitor, SC58125 (0.1- 10 microM), blocked leukocyte lipid body formation elicited by all three types of stimuli and also blocked priming for enhanced LTB(4) production and PGE(2) production. The effect of NS-398 on lipid body formation was independent of its inhibitory effects on COX-2 since arachidonate-induced lipid body formation in COX-2-deficient mouse leukocytes was also inhibited by NS-398. By means of its ability to inhibit leukocyte lipid body formation, NS-398 may exert actions independent of its COX-2 inhibition and more broadly contribute to the suppression of formation of COX-1 and lipoxygenase-derived eicosanoids.
Collapse
Affiliation(s)
- P T Bozza
- Harvard Thorndike Laboratory and Charles A. Dana Research Institute, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | | | | | | |
Collapse
|
36
|
Bandeira-Melo C, Bozza PT, Weller PF. The cellular biology of eosinophil eicosanoid formation and function. J Allergy Clin Immunol 2002; 109:393-400. [PMID: 11897981 DOI: 10.1067/mai.2002.121529] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eosinophils are capable of generating eicosanoid derivatives of arachidonic acid by means of cyclooxygenase and the 5- and 15-lipoxygenase (LO) pathways. Moreover, eosinophils, because of their expression of leukotriene (LT) C(4) synthase, are a major source of 5-LO-derived cysteinyl LTs, which are potent paracrine mediators of bronchial obstruction and inflammation pertinent to asthma. The regulation of eicosanoid formation within eosinophils involves activation of key enzymes at specific intracellular sites. Calcium ionophore-elicited translocation of 5-LO to the membranes of the nuclear envelope is associated with LTC(4) formation. In addition, lipid bodies, the formation of which is initiated by specific receptor-mediated signaling pathways, are sites of cyclooxygenase- and LO-pathway eicosanoid formation. Newly formed LTC(4) can be immunolocalized at perinuclear membranes in ionophore-activated eosinophils and at lipid bodies in CCR3 agonist (eg, eotaxin) chemokine-stimulated eosinophils. The local generation of eicosanoids at distinct sites within eosinophils may be important for the roles of these eicosanoids, both as paracrine mediators pertinent to inflammation and as intracrine signal-transducing mediators that help regulate cellular responses of eosinophils.
Collapse
Affiliation(s)
- Christianne Bandeira-Melo
- Department of Medicine, Harvard Thorndike Laboratories, Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | | | | |
Collapse
|
37
|
Bandeira-Melo C, Phoofolo M, Weller PF. Extranuclear lipid bodies, elicited by CCR3-mediated signaling pathways, are the sites of chemokine-enhanced leukotriene C4 production in eosinophils and basophils. J Biol Chem 2001; 276:22779-87. [PMID: 11274187 DOI: 10.1074/jbc.m101436200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eosinophils and basophils, when activated, become major sources of cysteinyl leukotrienes, eicosanoid mediators pertinent to allergic inflammation. We show that the C-C chemokines, eotaxin and RANTES (regulated upon activation normal T cell expressed and secreted), activate eosinophils and basophils for enhanced leukotriene C(4) (LTC(4)) generation by distinct signaling and compartmentalization mechanisms involving the induced formation of new cytoplasmic lipid body organelles. Chemokine-induced lipid body formation and enhanced LTC(4) release were both mediated by CCR3 receptor G protein-linked downstream signaling involving activation of phosphoinositide 3-kinase, extracellular signal-regulated kinases 1 and 2, and p38 mitogen-activated protein kinases. Chemokine-elicited lipid body numbers correlated with increased calcium ionophore-stimulated LTC(4) production; and as demonstrated by intracellular immunofluorescent localization of newly formed eicosanoid, lipid bodies were the predominant sites of LTC(4) synthesis in both chemokine-stimulated eosinophils and chemokine-primed and ionophore-activated eosinophils. Eotaxin and RANTES initiated signaling via phosphoinositide 3-kinase and mitogen-activated protein kinases both elicits the formation of lipid body domains and promotes LTC(4) formation at these specific extranuclear sites.
Collapse
Affiliation(s)
- C Bandeira-Melo
- Department of Medicine, Harvard Thorndike Laboratories, Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | | | | |
Collapse
|
38
|
Bozza PT, Weller PF. Arachidonyl trifluoromethyl ketone induces lipid body formation in leukocytes. Prostaglandins Leukot Essent Fatty Acids 2001; 64:227-30. [PMID: 11418016 DOI: 10.1054/plef.2001.0264] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Leukocyte lipid bodies, abundant in cells associated with inflammation, can be induced to form in response to stimuli that include cis -unsaturated, but not saturated, fatty acids. Arachidonyl trifluoromethyl ketone (AACOCF(3)), a non-esterifiable arachidonate analog and an inhibitor of cytosolic phospholipase A(2)enzymes (PLA(2)), dose-dependently (0-20 microM) stimulated neutrophil lipid body formation, but this stimulation was not attributable to PLA(2)inhibition. Palmitoyl trifluoromethyl ketone, also a PLA(2)inhibitor, failed to stimulate lipid body formation, like palmitic acid itself, and did not inhibit stimulated lipid body formation. Moreover, aspirin, indomethacin and ibuprofen, which inhibit cis -unsaturated fatty acid-induced lipid body formation, inhibited AACOCF(3)-induced lipid body formation. Lipid body induction with AACOCF(3)reflected its structural basis as a cis -unsaturated fatty acid analog. These results indicate that cytosolic PLA(2)enzymes are not active in lipid body induction and cis -fatty acid stimulation of lipid body formation does not require esterification of cis -fatty acids into glycerolipids.
Collapse
Affiliation(s)
- P T Bozza
- Immunopharmacology Laboratory, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil
| | | |
Collapse
|
39
|
Scarfo LM, Weller PF, Farber HW. Induction of endothelial cell cytoplasmic lipid bodies during hypoxia. Am J Physiol Heart Circ Physiol 2001; 280:H294-301. [PMID: 11123244 DOI: 10.1152/ajpheart.2001.280.1.h294] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lipid bodies (LBs), lipid-rich cytoplasmic inclusions found in many cell types, seem to act as nonmembrane sites of eicosanoid formation. Because alterations in eicosanoid products have been demonstrated in endothelial cells (ECs) during hypoxia, we investigated induction of LBs in systemic and pulmonary ECs exposed to acute and/or chronic hypoxia. LBs in ECs were O(2)-concentration dependent, increasing approximately fivefold during acute exposure to 0% O(2) in both cell types. During chronic exposure to 3% O(2), LBs were induced only in systemic ECs. LBs were not induced by other cellular stresses (heat shock or glucose deprivation). Subsequent studies suggested that protein kinase C-dependent and tyrosine kinase-dependent pathways are important in LB induction during hypoxia. PGH synthase was demonstrated in LBs in every case in which they were induced. These are the initial studies to demonstrate induction of LBs in ECs and to demonstrate LB induction during exposure to hypoxia in any cell type. These results imply that in ECs, LBs are structurally distinct inducible sites for synthesis of eicosanoid mediators.
Collapse
Affiliation(s)
- L M Scarfo
- Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | | | | |
Collapse
|
40
|
Phosphatidylinositide 3-kinase localizes to cytoplasmic lipid bodies in human polymorphonuclear leukocytes and other myeloid-derived cells. Blood 2000. [DOI: 10.1182/blood.v95.3.1078.003k16_1078_1085] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphatidylinositide 3-kinase (PI3K) is a key enzyme implicated in intracellular signaling of diverse cellular responses including receptor-mediated responses and neutrophil activation. Several PI3K subunits have been cloned and shown to be localized to plasma membrane receptors, the cytosol, or intracellular vesicles or caveolae. We report the localization of PI3K to a distinct intracellular site, cytoplasmic lipid bodies, in leukocytes. In U937 monocyte cells, PI3K p85 regulatory and p110β catalytic subunits were localized to lipid bodies by immunocytochemistry and/or immunoblotting and enzyme assays of subcellular fractions. In RAW murine macrophages, p55, p85, and p85β PI3K subunits were present at isolated lipid bodies. PI3K p85 was also shown to colocalize and, by co-immunoprecipitation, to be physically associated with phosphorylated Lyn kinase in lipid bodies induced to form in human polymorphonuclear leukocytes. These findings, therefore, indicate a novel site for PI3K compartmentalization and suggest that PI3K-mediated signaling is active within cytoplasmic lipid bodies in leukocytes.
Collapse
|
41
|
Johnson MM, Vaughn B, Triggiani M, Swan DD, Fonteh AN, Chilton FH. Role of arachidonyl triglycerides within lipid bodies in eicosanoid formation by human polymorphonuclear cells. Am J Respir Cell Mol Biol 1999; 21:253-8. [PMID: 10423409 DOI: 10.1165/ajrcmb.21.2.3489] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Increasing evidence suggests that the subcellular and glycerolipid localization of esterified arachidonic acid (AA) is a key factor in regulating its availability to lipases. The goal of the current study was to determine the potential of AA stored in triglycerides (TG) to serve as a substrate for lipases and 5-lipoxygenase during neutrophil (polymorphonuclear leukocytes, PMN) activation. PMN containing high concentrations of AA in TG were generated by culturing PMN in vitro with high concentrations of exogenous AA (eAA) for 12 h. Cellular AA increased 2- and 4-fold in PMNs incubated with 5 and 20 microM AA, respectively, and this increase was almost exclusively observed in neutral lipids (NL). Further analysis revealed that 88% of the AA in the NL fraction was associated with TG. Subsequent experiments were designed to determine whether this AA in TG could be mobilized and metabolized to eicosanoids during cell activation. TG pools of AA were increased as previously described and then PMN were stimulated with ionophore, A23187. In contrast to the 43-fold increase in TG AA after eAA loading (20 microM), free AA increased by only 1.9-fold after cell stimulation. Similarly, leukotriene (LT)B(4) production increased only 2-fold after loading TG with large quantities of AA. The magnitude of increase in free AA released and in LTB(4) formation was similar to the magnitude of increase in AA mass in phospholipase (PL), suggesting that PL, and not TG, served as the source of released AA and subsequent product generation. To confirm that AA in TG did not serve as a source for eicosanoid production, cellular pools of AA were differentially labeled with [(14)C]AA and [(3)H]AA, and the [(3)H]AA-to-[(14)C]AA ratio of LTB(4) and 20-hydroxyl LTB(4) produced during cell stimulation was measured. The [(3)H]AA/[(14)C]AA ratios of LTs were markedly different from the ratios in TG, thus providing further evidence that AA pools in TG are not a major source of AA for LT generation.
Collapse
Affiliation(s)
- M M Johnson
- Department of Medicine, Mayo Clinic Jacksonville, Jacksonville, Florida, USA.
| | | | | | | | | | | |
Collapse
|
42
|
Bozza PT, Yu W, Weller PF. Mechanisms of formation and function of eosinophil lipid bodies: inducible intracellular sites involved in arachidonic acid metabolism. Mem Inst Oswaldo Cruz 1998; 92 Suppl 2:135-40. [PMID: 9698925 DOI: 10.1590/s0074-02761997000800018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Lipid bodies, inducible lipid-rich cytoplasmic inclusions, are characteristically abundant in cells associated with inflammation, including eosinophils. Here we reviewed the formation and function of lipid bodies in human eosinophils. We now have evidence that the formation of lipid bodies is not attributable to adverse mechanisms, but is centrally mediated by specific signal transduction pathways. Arachidonic acid and other cis fatty acids by an NSAID-inhibitable process, diglycerides, and PAF by a 5-lipoxygenase dependent pathway are potent stimulators of lipid body induction. Lipid body formation develops rapidly by processes that involve PKC, PLC, and de novo mRNA and protein synthesis. These structures clearly serve as repositories of arachidonyl-phospholipids and are more than inert depots. Specific enzymes, including cytosolic phospholipase A2, MAP kinases, lipoxygenases and cyclooxygenases, associate with lipid bodies. Lipid bodies appear to be dynamic, organelle-like structures involved in intracellular pathways of lipid mobilization and metabolism. Indeed, increases in lipid body numbers correlated with enhanced production of both lipoxygenase- and cyclooxygenase-derived eicosanoids. We hypothesize that lipid bodies are distinct inducible sites for generating eicosanoids as paracrine mediators with varied activities in inflammation. The capacity of lipid body formation to be specifically and rapidly induced in leukocytes enhances eicosanoid mediator formation, and conversely pharmacologic inhibition of lipid body induction represents a potential novel and specific target for anti-inflammatory therapy.
Collapse
Affiliation(s)
- P T Bozza
- Harvard Thorndike Laboratory, Department of Medicine, Beth Israel Deaconness Medical Center, Boston, MA, USA.
| | | | | |
Collapse
|
43
|
Thore CR, Beasley TC, Busija DW. In vitro and in vivo localization of prostaglandin H synthase in fetal sheep neurons. Neurosci Lett 1998; 242:29-32. [PMID: 9509997 DOI: 10.1016/s0304-3940(98)00040-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Immunoreactive (IR) prostaglandin H synthase (PGHS) was evident in primary cortical cultures as early as day 2 after seeding. Labeling did not increase with time in culture, nor was there an apparent difference in IR intensity between 2 and 10% serum cultures or between glial and neuronal figures. PGHS-1 IR appeared as a homogeneous cytoplasmic fluorescence compared with PGHS-2 IR which tended to be more intense, particulate and exclusively perinuclear. PGHS-2(+) IR in both neurons and glia increased with time in culture. Immunofluorescence varied in intensity, but no significant degree of variation was seen between cell types. Neuronal PGHS-2 IR extended into processes and amassed in growth cones and at the leading edge processes of astrocytes. Novel rosette formations, possibly lipid bodies, were common in cultured neurons, but not astrocytes.
Collapse
Affiliation(s)
- C R Thore
- Department of Physiology, Bowman Gray School of Medicine, Winston-Salem, NC 27157-1083, USA.
| | | | | |
Collapse
|
44
|
Bozza PT, Yu W, Penrose JF, Morgan ES, Dvorak AM, Weller PF. Eosinophil lipid bodies: specific, inducible intracellular sites for enhanced eicosanoid formation. J Exp Med 1997; 186:909-20. [PMID: 9294145 PMCID: PMC2199047 DOI: 10.1084/jem.186.6.909] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/1997] [Revised: 07/11/1997] [Indexed: 02/05/2023] Open
Abstract
The specific intracellular sites at which enzymes act to generate arachidonate-derived eicosanoid mediators of inflammation are uncertain. We evaluated the formation and function of cytoplasmic lipid bodies. Lipid body formation in eosinophils was a rapidly (<1 h) inducible response which was platelet-activating factor (PAF) receptor-mediated, involved signaling through protein kinase C, and required new protein synthesis. In intact and enucleated eosinophils, the PAF-induced increases in lipid body numbers correlated with enhanced production of both lipoxygenase- and cyclooxygenase-derived eicosanoids. All principal eosinophil eicosanoid-forming enzymes, 5-lipoxygenase, leukotriene C4 synthase, and cyclooxygenase, were immunolocalized to native as well as newly induced lipid bodies in intact and enucleated eosinophils. Thus, lipid bodies are structurally distinct, inducible, nonnuclear sites for enhanced synthesis of paracrine eicosanoid mediators of inflammation.
Collapse
Affiliation(s)
- P T Bozza
- Harvard Thorndike Laboratory and Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA
| | | | | | | | | | | |
Collapse
|
45
|
Weller PF, Bozza PT, Yu W, Dvorak AM. Cytoplasmic lipid bodies in eosinophils: Central roles in eicosanoid generation. Allergol Int 1997. [DOI: 10.2332/allergolint.46.141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
46
|
Bozza PT, Payne JL, Morham SG, Langenbach R, Smithies O, Weller PF. Leukocyte lipid body formation and eicosanoid generation: cyclooxygenase-independent inhibition by aspirin. Proc Natl Acad Sci U S A 1996; 93:11091-6. [PMID: 8855314 PMCID: PMC38289 DOI: 10.1073/pnas.93.20.11091] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Lipid bodies, cytoplasmic inclusions that develop in cells associated with inflammation, are inducible structures that might participate in generating inflammatory eicosanoids. Cis-unsaturated fatty acids (arachidonic and oleic acids) rapidly induced lipid body formation in leukocytes, and this lipid body induction was inhibited by aspirin and nonsteroidal antiinflammatory drugs (NSAIDs). Several findings indicates that the inhibitory effect of aspirin and NSAIDs on lipid body formation was independent of cyclooxygenase (COX) inhibition. First, the non-COX inhibitor, sodium salicylate, was as potent as aspirin in inhibiting lipid body formation elicited by cis-fatty acids. Second, cis-fatty acid-induced lipid body formation was not impaired in macrophages from COX-1 or COX-2 genetically deficient mice. Finally, NSAIDs inhibited arachidonic acid-induced lipid body formation likewise in macrophages from wild-type and COX-1- and COX-2-deficient mice. An enhanced capacity to generate eicosanoids developed after 1 hr concordantly with cis-fatty acid-induced lipid body formation. Arachidonic and oleic acid-induced lipid body numbers correlated with the enhanced levels of leukotrienes B4 and C4 and prostaglandin E2 produced after submaximal calcium ionophore stimulation. Aspirin and NSAIDs inhibited both induced lipid body formation and the enhanced capacity for forming leukotrienes as well as prostaglandins. Our studies indicate that lipid body formation is an inducible early response in leukocytes that correlates with enhanced eicosanoid synthesis. Aspirin and NSAIDs, independent of COX inhibition, inhibit cis-fatty acid-induced lipid body formation in leukocytes and in concert inhibit the enhanced synthesis of leukotrienes and prostaglandins.
Collapse
Affiliation(s)
- P T Bozza
- Harvard Thorndike Laboratory, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215-5491, USA
| | | | | | | | | | | |
Collapse
|
47
|
Bozza PT, Payne JL, Goulet JL, Weller PF. Mechanisms of platelet-activating factor-induced lipid body formation: requisite roles for 5-lipoxygenase and de novo protein synthesis in the compartmentalization of neutrophil lipids. J Exp Med 1996; 183:1515-25. [PMID: 8666909 PMCID: PMC2192519 DOI: 10.1084/jem.183.4.1515] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Lipid bodies, lipid rich cytoplasmic inclusions, are characteristically abundant in vivo in leukocytes associated with inflammation. Because lipid bodies are potential reservoirs of esterified arachidonate and sites at which eicosanoid-forming enzymes may localize, we evaluated mechanisms of lipid body formation in neutrophils (PMN). Among receptor-mediated agonists, platelet activating factor (PAF), but not C5a, formyl-methyl-phenylalanine, interleukin 8, or leukotriene (LT) B4, induced the rapid formation of lipid bodies in PMN. This action of PAF was receptor mediated, as it was dose dependently inhibited by the PAF receptor antagonist WEB 2086 and blocked by pertussis toxin. Lipid body induction by PAF required 5-lipoxygenase (LO) activity and was inhibited by the 5-lipoxygenase-activating protein antagonist MK 886 and the 5-LO inhibitor zileuton, but not by cyclooxygenase inhibitors. Corroborating the dependency of PAF-induced lipid body formation on 5-LO, PMN and macrophages from wild-type mice, but not from 5-LO genetically deficient mice, formed lipid bodies on exposure to PAF both in vitro and in vivo within the pleural cavity. The 5-LO product inducing lipid body formation was not LTB4 but was 5(S)-hydroxyeicosatetraenoic acid [5(S)-HETE], which was active at 10-fold lower concentrations than PAF and was also inhibited by pertussis toxin but not by zileuton or WEB 2086. Furthermore, 5-HETE was equally effective in inducing lipid body formation in both wild-type and 5-LO genetically deficient mice. Both PAF- and 5(S)-HETE-induced lipid body formation were inhibited by protein kinase C (PKC) inhibitors staurosporine and chelerythrine, the phospholipase C (PLC) inhibitors D609 and U-73122, and by actinomycin D and cycloheximide. Prior stimulation of human PMN with PAF to form lipid bodies enhanced eicosanoid production in response to submaximal stimulation with the calcium ionophore A23187; and the levels of both prostaglandin (PG) E2 and LTB4 correlated with the number of lipid bodies. Furthermore, pretreatment of cells with actinomycin D or cycloheximide inhibited not only the induction of lipid body formation by PAF, but also the PAF-induced "priming" for enhanced PGE2 and LTB4 in PMN. Thus, the compartmentalization of lipids to form lipid bodies in PMN is dependent on specific cellular responses that can be PAF receptor mediated, involves signaling through 5-LO to form 5-HETE and then through PKC and PLC, and requires new protein synthesis. Since increases in lipid body numbers correlated with priming for enhanced PGE2 and LTB4 production in PMN, the induction of lipid bodies may have a role in the formation of eicosanoid mediators by leukocytes involved in inflammation.
Collapse
Affiliation(s)
- P T Bozza
- Harvard Thorndike Laboratory, Beth Israel Hospital, Boston, Massachusetts 02215, USA
| | | | | | | |
Collapse
|
48
|
Chilton FH, Fonteh AN, Surette ME, Triggiani M, Winkler JD. Control of arachidonate levels within inflammatory cells. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1299:1-15. [PMID: 8555241 DOI: 10.1016/0005-2760(95)00169-7] [Citation(s) in RCA: 182] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- F H Chilton
- Department of Internal Medicine, Bowman Gray School of Medicine, Winston-Salem, NC 27157, USA
| | | | | | | | | |
Collapse
|
49
|
Triggiani M, Oriente A, Seeds MC, Bass DA, Marone G, Chilton FH. Migration of human inflammatory cells into the lung results in the remodeling of arachidonic acid into a triglyceride pool. J Exp Med 1995; 182:1181-90. [PMID: 7595189 PMCID: PMC2192204 DOI: 10.1084/jem.182.5.1181] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Increasing evidence suggests that the metabolism of arachidonic acid (AA) may be different in inflammatory cells isolated from blood or migrating into tissues. To explore the possibility that changes in AA metabolism between blood and tissue inflammatory cells could be due in part to a different content or distribution of AA in glycerolipid classes, we studied these parameters in six human inflammatory cells isolated from blood (eosinophils, monocytes, neutrophils, and platelets) or from the lung tissue (mast cells and macrophages). Lung cells generally had a higher total cellular content of AA than that found in the blood cells. In addition, both mast cells and macrophages had a large endogenous pool of AA associated with triglycerides (TG), containing 45 and 22% of their total cellular AA, respectively. To address the hypothesis that cells migrating into the lung had a higher cellular level of AA and a larger AA pool in TG, we studied neutrophils isolated from the bronchoalveolar lavage (BAL) of patients with adult respiratory distress syndrome. BAL neutrophils had a fourfold increase in cellular AA as compared with blood neutrophils and contained 25% of their AA in TG versus 3% in blood neutrophils. BAL neutrophils also had a higher number of cytoplasmic lipid bodies (8 +/- 3/cell) relative to blood neutrophils (2 +/- 1/cell). High concentrations of free AA were also found in the cell-free BAL fluid of adult respiratory distress syndrome patients. To explore whether changes in BAL neutrophils may be due to the exposure of the cells to high concentrations of exogenous AA found in BAL, we incubated blood neutrophils in culture with AA (10-100 microM) for 24 h. Neutrophils supplemented with AA had a 10-fold increase in the amount of AA associated with TG and a sixfold increase in the number of lipid bodies. In addition, supplementation with AA induced a dose-dependent formation of hypodense cells. Taken together, these data indicate that human inflammatory cells undergo a fundamental and consistent remodeling of AA pools as they mature or enter the lung from the blood. These biochemical and morphological changes can be mimicked in vitro by exposing the cells to high levels of AA. This mechanism may be responsible for the changes in AA mobilization and eicosanoid metabolism observed in tissue inflammatory cells.
Collapse
Affiliation(s)
- M Triggiani
- Division of Clinical Immunology and Allergy, University of Naples Federico II, School of Medicine, Italy
| | | | | | | | | | | |
Collapse
|